### Decembe r 11,201 4 Mr . Joseph M . Kellmeye r One U.S . Ban k Plaz a S tLouis , Missour i 6310 1 Re : Evaluatio n o f

th e Xact ® Multi-metal s CEM S Mr . Kellmeyer : Pursuan tt o you r request

, I hav e evaluate

d th e us e o f th e Xact ® Multi-metal s Continuous Emission s Monitorin g Syste m (Xac tCEMS ) a

s se tfort h i n th e October , 201 4 Draf

tAi rPollutio n Contro l Titl e V permitt o Operat

e fo r Veoli a E S Technical Solutions , L.L.C . i n Sauget , Illinois . A s yo u ar

e aware, I hav

e managemen

tand engineering experienc e i n wast

e incineration , chemical manufacturing operation s an d environmenta

l remediation dating back t o 1980. M y experienc

e includes work i n hazardou s wast e incineration , hazardou s wast e fuel s managemen

t and combustion , uraniu m recover

y fro m phosphori c acid , an d th e productio n o f

sulfuri c acid , phosphori c acid , nitri c acid , ammonia, ammonium nitrates , granula r phosphat

e fertilizers , an

d nitroge n fertilizers . I

n recen tyear s an d throug

h my employmen

ta tB 3 Systems , Inc. , I hav e becom e extremel

y familia r wit

h Particulat

e Monitor s (PM ) fo r EP A MAC T Compliance an d Process Control . I n th e October , 201 4 Draf

tAi rPollutio n Contro l Titl e V permi tt o Operat

e fo r Veolia , USEP A Regio n V propose

s tha tVeoli a "install , calibrate , maintain an d operat e a n x-ra y flourescenc

e multi-metals CEM S fo r us e a s a continuou

s parametric monitorin g syste m (CPMS ) o n Units 2 , 3 an d 4 withi n 1

2 month s (36 5 days) afte

r this permitbecome

s effective... " Draf

tTitl e V Permi

t a t34 . I n footnot

e 4 6 o f th e Statemen

to f Basis , USEP A state

s tha titis "awar

e o f on e commerciall y availabl e multi-metals CEM S - th e Xact ® Multi-metal s CEM S manufacture d an d distributed b y Coope r Environmenta l Services , LL C ("Cooper") . I n orde r t o provid e yo u wit

h my opinion , I hav

e extensively investigated th e Xac tCEMS . Base d upon m y investigation an d m y knowledg

e o f P M Monitor s an

d stac k emissions , I hav

e conclude d tha

ti f th e Xac tCEM S wer

e installed an

d operate

d a s propose d i n th

e draf tTitl e V permit, th

e Xac tCEM S woul d no tprovide a

n accurat

e indicatio n o f

metal s emissions . Du e t

o m y experienc

e wit h P M CEM S an

d knowledg

e o f th e dynami c P M flow i n duct s an d stacks , I d

o no t believe th

e Xac tCEM S wil l produc e result s wit h th e accurac

y indicated b y EP A an d th e previou s validatio n work . Further, I believe tha tMetho d 30 1 work is biased positiv e b y th e testin g scenario (e.g , usin g th e QA G an

d no tMetho d 29 under process conditions) . Ke y Issues Th e followin g i

s a summar

y o f ke y item s raised abou

tth e Xac tCEMS : Draf tPermi tLanguag e & Statemento f Basi s [8

] [11 ]

• USEP A state

s th e Xac tCEM S i

s bein g installe d a

s a continuous parametric monitoring syste m ("CPMS") . However, a CPM S limi to n a n operationa

l combustor i

s alway s 6073833.2



## VES01699 7

### establishe d durin g CP T testin

g i n orde

r t o establish a known relationship , i f any , betwee n th e CPM S and th

e paramete

r tha ti s sough tt o b e monitored .

• USEP A state

s th e Xac tCEM S is bein g established a s a CPM S o n a temporar y basis . However , this temporar y CPM S i

s bein g use

d a s a n absolut

e emissio n rat

e fo rprovidin g evidence o f

deviations tha

tindicat e tha tVeoli a ma

y no tb e i n complianc e wit h a HW C MAC T metals emissions limit . Base d o n my experience , th e HW C MAC T recognized feedstrea

m analysi s pla

n is use d a s evidence o f

compliance - a temporar y CPM S is neve r used a s evidence o f

compliance . Draf

tPermita

t55 .

• Base d o n my experience , a temporar y CPM S tha

tha s notbeen establishe

d throug

h CP T testing shoul d no

thav e an y impac to n a feedstrea

m analysis pla n tha

ti s permanen

tan d wa s established throug

h CP T testing . Proces s Condition s

• Th e majorit

y o f th e metal s fro m th

e dr y process tha

tVeoli a use

s ar e i n th e for m o f particulat

e matte r (PM) .

• Th e biggestconcern fo ran y device monitorin g PM , includin g a Xac tCEM S tha tpurport

s t o monito r multi-meta

l particulates , i s obtaining a representativ e sample a

tth e detector

.

• A s a resul

to f variation

s during normal operation , th e P M emitte

d i s no tsize selective .

• Further, industr

y an d academi

a provide s severa

l reference

s and studie

s fo rpneumati

c conveyin g o f

solid s suc

h a s multi-meta

l P M foun d on stacks . Afte r a bend , th e majorit

y o f studie s documen

t"roping " or hig h concentration o f P M o n oute

r wall . Velocit

y profil e normalizes , bu

thighe r P M concentration s sta y close r t

o th e wal l an d ca

n b e shifted aroun d base d on the ga

s flo w dynamics tha

tca n var y durin g norma

l operation .

• I n Veolia' s dr

y process , th

e induce d draf t(ID ) fan defines the P M mixin g an d dispersion i n th e downstrea

m duct/stack.

• P M stratification i n system s suc h a s Veoli a is par

to f a dynami c process tha tvarie s durin g norma l operations . Th e dynamic change s i n a syste

m (flow , temperature, particle size , particl e density , etc. ) wil l also chang e th e P M dispersion .

• Base d on a revie w o f stac k velocitie s a

tVeoli a fro m th

e 201 3 CP T results , th e ga s velocitie s ar

e hig h enoug

h t o easily carr

y particl e sizes u

p t o 100-15 0 microns . Xac tCEM S

• Th e Xac tCEM S use s Othe r Tes tMetho d 1

6 (OTM16 ) whic h Coope r developed b y whic h th e Xac tCEM S purport s t o obtain a discrete , quantifiabl e readin g fo r eac h o f th e multi metal s tha ti ttests . B y comparison , P M CEM S us e Performance Specificatio n 1 1 ("P S 11") an d d o notus e OT M 16. Further, P M CEM S resulti s merely a "relative " outpu tand 6073833.2 -2 -



## VES01699 8

### require s Metho d 5 (M5 ) t

o calibrat

e it . P M CEM S d

o no tobtain a discrete , quantifiabl e reading .

• Th e Xac tCEM S ha s bee n validated , usin g M301 , agains ta n early versio n o f

th e quantitativ

e aerosol generato

r (QAG) . Th e earl

y versions o f

th e QA G generate

d particles approximately 1 micro n i n size o r less which ar e particles tha

ttranspor

twell . Unfortunately , th

e QA G is no

trepresentativ

e o f Veolia' s proces s conditions whic h ma y consis to f

large r particles .

• Th e Xac tCEM S work s fro m a singl e pointsamplin g location . A single poin tsampling locatio n canno

tobtai n a sampl

e a s representativ

e a s a traversin g sampling collectio n syste m unde r changing process conditions . Overvie w an d Furthe r Discussio n Base d o n m

y experienc

e an d th e documents/information reviewed , th e performanc

e specification s writte

n fo rth e Xac tCEM S ar

e simila r t

o thos e writte n fo r gaseou

s CEM S applications . However , a n Xac tCEM S function s mor e lik e a P M CEM S an d ga s CEM S (e.g. , CO , 0 2 

### , THC , etc. ) i n th e fac ttha ti tmus tsample particulat

e matter . Therefore , base

d o n experienc

e an d knowledge tha

tB 3 System

s ha s gained fro m P M CEM S applications , basic performanc

e specificatio n requirement s develope d fo r th

e Xac tCEM S ar

e no tvali d fo r transportin

g multi-meta

l P M fo r quantification . Based o n ou

r experienc

e an d research, th

e biggestissu

e wit h th e Xac tCEM S is gettin g a representativ

e sample t

o th e detector

. Transportin g P M i

s no tcomparable t

o transportin

g a gas . [1] . Wor k wit h P M CEM S demonstrate s tha tsystem s ca n an d d o hav e P M stratification issues . Veoli a use s a baghous

e fo r P M removal . However , base d upon my revie w o f

th e 2009 an

d 201 3 CP T tes tdata, particl e siz e ma y var y dependin

g upo n operationa

l conditions an

d dr y particle

s o f al l size s ma y b e transferre

d int o th e clean-ga

s side o f th e baghous

e and carried t

o th e stack. Give n this fact , th

e representativenes

s o f a singl e poin tsourc

e suc h a s th e sourc e th e Xac tCEM S use

s t o sampl e is very questionable . I hav e observed whil e workin g wit h P M CEM S tha

ta chang

e i n particle densit

y ca n an d doe s affec tth e accurac

y o f th e result s o f th e singl e pointsampling system s suc h a s th e samplin g syste

m which exist

s i n th e Xac tCEMS . P M CEM S v s Xac tCEM S Th e P M CEM S an

d th e Xac tCEM S sampl

e particulat

e matter , wit h th e P M CEM S indicatin g tota l particulat

e matte r an d th e Xac tCEM S measuring particulat e matte r fo r selectiv

e multi meta l content . USEP A Performanc e Specificatio n 1

1 (PS 11 ) define s th

e procedure

s fo rP M CEMS . PS1 1 use

s a n EPAManua l Reference Metho d (RM ) t o calibrat

e th e P M CEM S unde

r thre e (3) level s o f

P M concentration . Thi s mean s tha ti f th e monitorin g locatio n is no tideal , the

n

6073833.2 - 3 -



## VES01699 9

### th e dat a fro m th

e traversing R M i

s use d t o calibrat

e th e singl e pointsamplin g CEMS. 1 

### Th e R M result s compensat

e fo r th e imperfection in th

e singl e pointsamplin g location . Th e Xac tCEM S o

n th e othe r han d measur

e metals i n absolut

e term s an d purport

s t o obtain a representativ

e sampl e from a single sampling point . Therefore , i f th e Xac tCEM S fail s t

o obtain a representativ

e sampl e fro m th

e stac k t o be examined b y th

e detector

, th e outpu to f th e Xac t CEM S wil l b e incorrect. Based o n th e actua l samplin g locatio n ofth e Xac tCEMS , ther e i s a ver y hig h possibilit

y tha tth e Xac tCEM S outpu

twil l no tmatc h th e actua l emissions sinc

e i tdoe s no thav e an y wa y o f compensatin

g fo rP M stratificatio n unde r changin g proces s conditions . Dependin g o n th

e stac k ga s samplin g location , th e sample collecte d coul d b e higher o r lower in metals/PM tha

n th e overal l averag

e concentration . Sampl e Transpor t Th e Xact ® ha

s bee n challenged agains

tth e QAG . 1 thin

k th e QA G i s a

n excellenttool t

o verif y th e detector

, similar t

o a calibration ga

s fo r othe

r CEM S sinc

e i tgenerate

s a known concentration o f metal . Howeve r I fee l tha tth e QA G doe

s no trepresen

trealit y when itcome

s t o representin

g process conditions a

tVeolia . Onl y recently , an d base d o n wor

k fo rP M CEM S calibration , ha s Coope r Environmenta l Services (CES ) create d a versio n ofth e QA G tha tcreat e particl e size

s muc h greate r tha n 1 micro n [4] . Durin g th e time tha

tth e Xac tCEM S wa

s bein g validated , th

e QA G bein g used t

o validat e th e Xact ® coul d have onl y produced meta l salt s i n th e resulting ga

s strea m tha twer e approximatel

y 1 micro n o r less . Particles being emitted fro m industria l processe

s ar e no tcontrolle d o r define d b y approximately 1 micro n o r less . Base d o n dat a fro m Veolia' s 201 3 CP T testing , stac k velocitie s across al l samplin g train s o n Units 2 , 3 an

d 4 average d 31. 2 ft/sec 30. 8 ft/sec an d 56.8 ft/sec , respectively . A t30 ft/se c (9. 1 m/s) , larg e particles , 10

0 micro n an

d greater

, ca n b e transporte

d u p th e stac k base d o n a review o f

termina l settlin g velocities . [3] . Particles o f

almostan

y size ar e dense r tha n thei r surrounding flui d (air ) an d therefor

e hav e mor e mass. Thi s extr

a mas s mean s the y d o no tac tlik e a gas , especiall y onc e th e particl e siz e start

s t o b e greate r tha n 5-1 0 microns . I hav e reviewed severa

l studie s [4] [5 ] [6 ] o n pneumati

c conveyin g o f particles . I

n almostever

y case , th

e researc

h discovere d tha

tafter th e particles mad

e a turn , suc h a s transitioning fro m a horizonta l duc tt o a stack, th

e particle s forme d a rope , "hors e shoe " o r"U " patter

n o n th e opposit

e sid e o f th e vertical wall . Thi s mean s tha tth e particles on th

e wal l ar e no ti n th e Centroi d (i.e . noti n th e cente r o f th e stack ) tha tOTM-1 6 require

s fo r sampling . Th e sample required b y OTM-1 6 i s therefor e no trepresentativ

e ofth e conditions i n th e stack. Thi s erro

r i s compounded whe

n th e Xact ® take

s it s sub-sample since i tis ver y probable tha

t large r particles coul d stil l b e nea r th e wal l an

d therefor

e th e sub-sample woul d mis s them . The particle s generate d b y th e QA G i n us

e a tth e time th

e Xac tCEM S wa

s bein g validated wer

e ver y fin e and woul d b

e les s affecte d b y thes

e conditions . Therefore , I d o no tbelieve tha

tth e QA G i s representativ

e o f actua l process conditions a

tVeoli a an

d wil l no

tprovid e representativ e result s whe n auditing th

e Xac tCEM S transpor tsyste m and/or validatin g th e overal l syste

m a t Veolia . 1 Traversin g i n it

s simplestmeaning i

s takin g sample

s fro m multipl e locations in th e stac k an d intergratin

g thes e int o on e sample . 6073833.2 - 4 -



## VES01700 0

### P M transportatio n i s easies ti n a downward , vertica l directio n du

e t o gravit y or i n a n upward , vertica l directio n du

e t o th e force ofth e gase

s workin g againstth

e gravitationa

l pull . Particl e transportatio

n is mos tdifficul tfo rhorizontal an d incline d runs . EP A referenc e method

s us e samplin g probes (i.e . horizonta l transpor

truns) . Althoug h the stac k gase s ar e bein g sample

d isokineticall y (i.e . a

tth e sam e velocit y a s th e stac k flow) , based o n th

e nozzl e diameter

, th e actua l flo w rat

e i n th e probe canno

tcarr y th e large r particle s throug

h th e probe and t

o th e filter . Thi s droppin g ou

to f th e P M is know

n a s "saltation " and account s fo r a s muc h a s 60 % t o 80 % o f th e P M endin g u

p i n th e probe . Thi s is easil y see n b y reviewin g th

e detaile d P M result

s fro m th

e CP T test , Tables 4-14,4-1 5 & 4-1 6 ofth e CP T Report. Thi s i s further supporte d b y detailed analysis o f

th e metal s sampling train

s i n Tables 4-20,4-2 2 & 4-24 . B y reviewin g th e tota l metal s catc h i n th e prob e & nozzl e rinse (PNR ) t o th e tota l yo u ca n se

e tha tth e larg e portio n ofth e metal s sho w u p i n th e probe , wit

h th e exception o f

mercury . EP A referenc e method

s requir e th e recover y o f th e PM/metal s fro m th

e prob e an

d nozzl e fo r analysis . Th e Xac tCEM S doe s no t requir e recover

y o f th e multi-metals P M fro m th e prob e and umbilical . I f th e P M doe

s no tmak e i tt o th e filte r o f

th e Xact® , the

n th e result s wil l no tbe analyzed and th

e Xac tCEM S wil l no

t produc e result s consisten

twit h th e actua l stac k gases . Likewise , i f

accumulate

d P M i n th

e probe nozzle , an

d umbilica l brea

k free during operation , thos e P M - potentially carryin g metal s - woul d b e analyze d b y th

e Xac tCEM S eve

n thoug h the y ar e no trelated t

o curren tstac k conditions . I n summary , th

e Xac tsyste

m ha s multipl e opportunitie s fo r sample transpor

trelate d issues . The firs ti s obtainin g a representativ e sampl e fro m th

e stack. Th e second i s transportin g th e stac k sample throug

h th e larg e diamete

r stac k prob e [10

] an d umbilica l t

o th e stillin g chamber. Th e thir d i s takin g a representativ e isokineti c subsampl

e [12 ] fro m th

e stillin g well . Th e fina l transpor trelated issu

e is gettin

g th e subsampl

e t o th e filte r tape fo r analysis . Base d o n my knowledg

e and experienc

e wit h P M CEM S an

d solids transport

, I d o no tthin k th e Xac tca

n obtai n a n absolut

e representativ

e sample a

tth e detecto r versus th

e EP A referenc

e method (M29) . I thin k th e dynami c conditions i n th e stac k gase s combine d wit

h the sampl

e transpor

tissue s discussed abov

e ar e impossible t

o overcome fo r a single poin tsamplin g syste m wher e a larg e majorit y ofth e metal

s ar e i n th e for m o f

PM . Coope r an

d USEP A mak

e muc h o f Xac tCEM S us

e fo r a brie f

perio d o f

tim e a tth e El i Lill y facility i n Indiana . Th e El i Lill y facility i n Indiana use d a wetscrubber

, no tth e dr y baghous

e syste m utilize d b y Veoli a in Sauget , Illinois . Th e system

s a tth e two facilitie s ar

e completely differentan d therefor

e produc

e P M includin g multi-meta l P M tha

tar e o f a completely different type, size an d characteristic . Thus , whethe r th e Xac tCEM S worked an d produce d accurat

e result s a tEl i Lill y i

s no tpredictive a

s t o whethe

r th e XAC T CEM S wil l wor k an d produce accurat e result s a tVeolia . Forth e reason

s se tfort h above , I d

o no tbelieve th

e Xac tCEM S wil l produc e accurat

e result s i f employed a

tth e Veoli a Sauge

tIllinoi s facility .

6073833.2 - 5 -



## VES01700 1

### Reference s 1 . Th e on

e exception i

s tha tsmall P M particle s ma y "ac tlike a gas" , bu

tprimaril y fo r sub micro n particle

s (< 1 micron) an

d specificall y wher

e particle approac

h molecular size (~0. 1 micron) "Fundamental s o f Ga s Solids/Liquid s Separation , Muelle r Environmenta l Designs , Inc. 2 . "A n Investigation o f th e Particle Dynamic s o f a Multi-componentSoli d Phas e i n a Dilut e Phase Pneumatic Conveyin g System" , Lu , Tong , Thesi s submitte d fo r th e degre e o f Docto r o f

Philosophy , Th e Universit y o f Edinburgh , Marc h 09 3 . "Perry' s Chemical Engineerin g Handbook" , Fourt h Edition , Figure 5-74 , P g 5-6 2 4 . "Quantitativ

e Aeroso l Generator (QAG ) fo r P M CEM S Calibration" , Presentatio n a t EUE C 201 4 5 . "Mixin g an

d dispersio n o f

particl e rope s i n lean phase pneumati c conveying" , Harun Bilirgen , Edward K . Levy , Energ y Researc

h Center, Lehig h University , 11 7 ATLS S Drive , Bethlehem , P A 18015 , US A 6. "Experimenta

l an d Numerical Stud

y o f Dilut e Gas-Soli d Flo w insid e a 90 ° Horizonta l Squar e Pip e Bend" , Wali d Anis s Aissal , Tarek Abde l Malak Mekhaill , Soubhi Al i Hassanein , Osam

a Hamdy , Open Journa l o f Flui d Dynamics , 2013 , 3 , 331-339 7 . "Validatio n o f

Thre e Ne w Method

s fo r Determinatio n o f Metal s Emission s Usin g a Modifie d Environmenta l Protectio

n Agenc y Metho d 301" , Journa l o f Ai ran d Wast e Managemen

tAssociation , 200

6 8 . Statemen

to f Basi s fo r DRAF T Titl e V PermitNo . V-IL-1716300103-2014-10 , October 201 4 9 . Comprehensive Performanc e Tes tRepor tfo r Fixe d Heart

h Incinerator - Uni t2 , Fixe d Heart h Incinerator - Uni t3 , Rotar y Kil n Incinerator - Uni t4 , Januar y 201 4 10 . Revie w o f

Monitorin g Experienc e wit h th e Xac tMulti-Metal s CEMS , Kra g Peterson, Coope r Environmental , IT3 201 4 Pape r & Presentation , Pape r 2 9 11. DRAF T Titl e V PermitNo . V-IL-1716300103-2014-10 , October 201 4 12 . XAC T TM 64

0 Monitorin g Syste

m Spe c Sheet

, Coope r Environmenta l

6073833.2 - 6 -

# VES017003-017018.pd f

# ^^^ J FUNDAMENTAL S O F ^ c - fwd

GA S SOLIDS/LIQUID S
m i 

# SEPARATIO N



# Muelle r Environmenta l Designs , In c

NoiselContro l Mis tEliminatio n



## VES01700 3

# Fundamental s of Ga s Solids/Liquid s Separatio n Man yproces s operation s requir e th e remova l o f entraine d non-ga s particle s fro m multi-phas e ga s streams . Th e remova l o f thes e non-ga s particle s i s th e proces s i n itsel f (captur e o f a valuabl e product ) o rth e proces s o f cleanin g a ga s strea m i n orde rt o protec t eithe rstationar yo rrotatin g equipmen t fro m th e harmfu l effect s du e t o non-ga s particle s enterin g thos e devices
. Th e remova l o f entraine d non-ga s particle s fro m a multi-phas e ga s strea m i s a separatio n proces s involvin g th e remova l of : Liqui d particle s fro m a ga s o rvapo rstream ; Soli d particle s fro m a ga s o rvapo rstream ; Combinatio n o f bot h liqui d an d soli d particle s fro m a ga s o rvapo rstream . I n orde rt o understan d mechanica l separatio n concepts , a basi c understandin g o f particl e formation , physic s an d motio n i s required
. 

## Particl e Formatio n No n ga s particle s ar e generate d an d entraine d i n th e ga s strea m (spra yregime ) o rar e converte d t o a shee t flo w (annula rregime ) an d carrie d o n th e flui d strea m boundary
. Thes e liqui d non-ga s particle s ca n b e generate d fro m a pur e ga s du e t o a gas-liqui d phas e chang e occurrin g withi n a stat e chang e o f th e gas . Thi s chang e o f stat e i s commonl yknow n a s condensation
. Th e followin g graphi c i s th e pressure-volum e char t fo ra typica l vapor . I t i s onl yi n th e ga s liqui d multi-phas e zon e tha t liqui d no n ga s particle s ca n exist
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0 

### Th e critica l poin t "C " (Se e Pressure -

Volum e Char t Graphic ) i s th e stat e poin t a t whic h th e liqui d an d ga s phase s ar e identical
. A t highe rpressure s alon g th e critica l isotherm , a sligh t increas e o r decreas e i n temperatur e wil l instantaneousl yproduc e a complet e phas e change
. A t a temperatur e highe r tha n th e critica l isotherm , n o liqui d phas e wil l b e encountered
. A t temperature s belo w th e critica l isother m ga s ca n exis t a s bot h a ga s o rliquid
. Th e amoun t o f liqui d pe runi t volum e o f mixtur e ca n b e estimate d usin g th e know n physica l propertie s o f th e mixture
. Liqui d particle s ca n b e forme d i n mi d strea m b ycondensin g initiall ya t th e molecula rsiz e level
. Thes e particle s the n ca n b e carrie d b yth e flui d stream . Condensatio n o n coo l surface s wil l produc e a liqui d fil m whic h i s swep t of f th e surfac e b ydra g forc e du e t o th e ga s strea m velocit ybein g greate rtha n th e surfac e tensio n o n th e liquid
. Liquid s injecte d int o th e strea m ma yb e born e alon g i n th e strea m i f i n smal l



## VES01700 4

### particl e form
. Th e liqui d strea m injecte d wil l b e

disburse d initiall ydu e t o tha t forc e overcomin g th e surfac e tensio n forces
. Th e liqui d wil l becom e par t o f th e mixtur e an d ha s th e potentia l t o als o chang e state . Smal l liqui d particle s o f lik e substance s wil l joi n wit h on e anothe rupo n collisio n i n wha t i s calle d coalescence
. Th e rat e a t whic h th e particle s wit h n o ne t movemen t wil l joi n togethe ri s dependen t o n ga s viscosit yan d temperatur e an d th e numbe r o f particle s present . Highe rtemperatures , lowe r viscosities , an d flo w strea m agitatio n wil l provid e highe rcoalescenc e rate . Liqui d presen t withi n th e ga s strea m wil l flo w i n on e o f severa l flo w regimes
. Figur e 2 depict s th e variou s flo w regime s tha t occu rwithi n multi-phas e ga s streams . Th e tw o flo w regime s tha t provid e th e lowes t liqui d t o ga s weigh t rati o ar e annula ran d spra yflow
. Annula r flo w i s characterize d b yfinit e liqui d amount s carrie d i n suspensio n wit h significan t amount s alon g th e pip e wall
. Spra yflo w regim e i s characterize d b yparticle s i n suspensio n i n th e ga s wit h negligibl e amount s o f liquid s o n th e pip e wall
. Slu g flo w regim e i s ofte n encountere d i n ga s stream s wit h greate rliqui d t o ga s weigh t rati o tha n annula ro rspra yregimes
. Liqui d particle s ar e generall yidealize d a s bein g spherica l i n shap e sinc e thi s i s th e shap e surfac e tensio n force s impart
. Liqui d particle s migh t hav e shape s othe rtha n thi s dependin g o n othe r force s suc h a s gravit yan d drag
. Soli d particle s ar e als o idealize d a s bein g spherical , thoug h i n realit yhav e irregula rshapes
. 

## Blac k Powde r

Wha t i s it ? Blac k

powde ri s a catchal l ter m tha t describe s materia l tha t collect s i n ga s pip e line s an d create s wea ran d reduce d compresso refficiency , clogge d instrumentatio n an d valves , an d flo w losse s i n lon g pip e lines
. Th e materia l ca n b e wet , wit h a tar-lik e appearance , o rdr yan d b e a fin e powder
. Chemica l analyse s revea l i t i s an yo f severa l form s o f iro n sulfid e an d iro n oxide
. Further , i t ca n b e mechanicall ymixe d o rchemicall ycombine d wit h an ynumbe r o f contaminants , suc h a s water , liqui d hydrocarbons , salts , chlorides , san d o rdirt
. Som e pip e line s hav e black-powde rproblem s an d other s d o not . I t appear s thos e line s close rt o th e ga s gatherin g en d o f th e syste m hav e problems , whil e thos e a t th e distributio n end , wit h relativel y smal l systems , d o not . Blac k powde ri s foun d i n bot h "dry " an d "wet " lines
. On e paralle l lin e ca n hav e a proble m whil e th e othe rdoe s not . N o pip e lin e ha s bee n identifie d t o dat e tha t ha s bee n abl e t o eliminat e th e proble m onc e i t starts . Flo wRegime s GAS—* ) (a ) Bubbl e (e ) Slu g GA S (b ) Plu g (f ) Semi-annula r GA S (c) Stratifie d GA S (d ) Wav y GA S (g ) Annula r

(h ) Spra y Figure 2



## VES01700 5

## Particl e Physic s

Th e force s impose d o n particle s i n mechanica l separator s ar e gravity , dra g an d inertia l forces
. Gravit yforce s ac t verticall ydownward
. Dra g force s ar e resistiv e forces
. Inertia l force s ar e a resul t o f particl e circula r motion
. Particl e circula rmotio n generate s centripeta l force ; a forc e tha t i s directe d toward s th e cente ro f th e circula rmotion
. Opposit e t o centripeta l forc e i s centrifuga l forc e an d i s du e t o a force d turnin g o f th e ga s stream , an d act s a t righ t angle s t o th e particl e angula rmotion
. Centrifuga l forc e i s th e principl e determinan t i n th e operatio n o f cyclon e an d impingemen t typ e separators . Thi s actio n i s bes t describe d i n a rectangula r vecto rcoordinate s a s show n i n figur e 3 . Th e particl e i n motion , i f no t a t th e wall , wil l accelerat e radiall yt o th e wall , an d i n th e proces s absor b som e o f th e centrifuga l force
. Th e particl e dra g force s ac t i n th e directio n ofth e particl e motion
. Dra g force s ar e i n respons e t o th e viscou s effect s o f th e ga s opposin g th e particl e motion
. Dra g force s ar e compose d o f pressur e difference s an d shearin g stresse s o n th e surfac e o f th e particle
. Additionally , a buoyan t forc e i s presen t du e t o displacemen t o f th e ga s b yth e particle
. Thi s forc e i s insignifican t o n particle s greate rtha n 0. 1 microns
. Particle s 0. 1 micron s an d smalle rapproac h molecula rsiz e wher e buoyan t force s becom e considerabl e i n relatio n t o particl e siz e an d becom e a facto ri n Brownia n Movement
. Brownia n Movemen t i s th e motio n exhibite d b ysmal l particle s tha t mov e non-uniforml yalon g th e ga s streamline s du e t o collision s wit h ga s molecule s (additiona l informatio n regardin g Brownia n Movemen t wil l follow)
. Significan t comple xparticl e motio n (rectilinea ran d curvilinear ) translatio n exist s abou t th e axi s o f th e particle
. Pur e particl e motio n abou t th e rotationa l axi s exist s bu t i s no t a s significan t a s th e comple xparticl e motio n translation
. O n th e particl e boundar ylaye rshea rstresse s o f th e ga s strea m ar e oppose d b yth e surfac e tensio n ofth e gas-liqui d interface
. Th e liqui d particl e syste m ma ychang e relativ e t o th e magnitud e o f th e shea rstres s an d surfac e tension ; suc h a s i n th e instanc e o f liqui d particle s ma yb e generate d fro m shee t flo w (strea m o f liquid ) an d larg e particle s ma yb e broke n int o smalle r particle s i f th e shea rstres s i s large rtha n th e surfac e tension
. A s previousl yestablished , th e physic s tha t gover n separato roperatio n ar e thos e whic h determin e th e force s an d stresse s actin g o n particle s i n th e ga s stream . Th e physica l phenomen a tha t generat e dra g force s ar e dependen t o n particl e size , shape , velocity , an d o n th e ga s stream' s densit yan d viscosity
. Fo rsmal l particle s o rlo w velocities , viscou s force s ar e dominant
. Fo rlarge rparticle s an d highe r velocitie s inertia l force s ar e dominant
. Thi s dynami c rati o o f inertia l t o viscou s force s i s a dimensionles s numbe rreferre d t o a s th e Reynold s Numbe rabbreviate d - Re
. Th e Reynold s Nurnbe rprovide s a determinatio n o f whic h regime , inertia l o rviscous , i s dominant
. Thi s dynami c rati o i s graphicall ydepicte d i n Figur e 4 . Ga s Motio n Particl e bein g propelle d b ygas , wit h th e ga s velocit y

exceedin g th e particl e velocity
. Th e particl e i s sai d t o "drag " behin d th e gas , an d thi s retardin g (slippage ) i s cause d b yth e dra g forc e bein g slightl y les s tha n th e ga s impac t forc e o n th e particle
.

Ga s Rotatio n

Note : ~--i<'' F c - Centrifuga l F d - Dra g F g - Gravit y E F - Tota l Force s actin g o n a particl e du e t o circula racceleratio n generate s particl e motio n alon g vecto rEF
.



## VES01700 6100,00 0

T J L L 10,00

0



### o 0 ) o O 

### Q 1,00

0

10 0

1 0

1. 0

0. 1 Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified )

Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified ) 

### \ Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified ) • — Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified ) 1 

### V " Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified )

Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified )

Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified )

Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified ) 

## \ Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified )

Symbol s an d Legen d A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified ) s : Symbol s an d Legen d

A p = Are a o

f Particl e Projecte d o n Plan e Norma l t o directio n o f Flo w o rMotion , sq . ft. C = Overal l Dra g Coefficient , Dimensionles s D p = Diamete ro f Particle , ft
. F d = Dra g o rResistanc e t o Motio n o f Bod yi n Fluid , Poundal s N R e - Reynold s Number , Dimensionles s u = Relativ e Velocit yBetwee n Particl e an d Mai n Bod yo f Fluid , ft./sec , ^ = Flui d Viscosity , {lb.mass)/{ft.)(sec.)-Centiposi s 148 8 P = Flui d Density , (ib.mass)/(cu.ft. ) (an yConsisten t Syste m o f Unit s ma yb e Employe d i n Plac e o f th e Englis h Unit s Specified ) 

## \ { Sphere s • Disk s

. Cylinder s 1 

### , \ Sphere s • Disk s

. Cylinder s i - Sphere s • Disk s

. Cylinder s 

# \- r t J

_

# 4 J J i , 

### | i 1 H-H - 

### —-

1 1 —Stokes ' Law - I r t < e d a t

e Law- * -Newton' s La w 

# - • L 

### III I 1 1 II I I III I I 1 J L 1 til l 1 

# 1 0.000 1 0.0O

1 0.0

1 0. 1 1.

0 1 0 10 0 Reynold s Number , Np e = — — 1,00 0 10,00

0 100,00

0 1,000,000 

### Dra g Coefficients

for Spheres, Disks, And Cylinders

and Any Fluid. From

Perry, R. H., Ed., Chemical Engineers

Handbook, 7th. ed.. 1997, McGraw Hill Company, Inc. Figure 4 

### Dra g forc e o n spherica l particle s 3 t o 10 0 micro n i s directl yproportiona l t o velocit yi n lo w Reynold' s numbe rregion
. Th e applicabl e physica l la w i s Stokes ' La w an d a t R e < 2. 0 th e flo w i s lamina r an d streamline s ar e smooth , i t i s considere d t o b e "creepin g flow " aroun d th e spherica l particle
. Particle s les s tha n 3 micron s i n th e R e < 2. 0 regim e ar e subjec t t o Brownia n Movemen t an d Stokes ' - Cunningha m Law
. Se e Figur e 5
. Ga s Velocit yExceed s Particl e Velocit y

Creepin g Flo w A t R e < 2 flo w i s lamina ran d streamline s smoot h Figure 6 

### Whe n a particl e fall s unde rth e influenc e o f gravit y i t wil l accelerat e unti l th e frictiona l dra g i n th e flui d balance s th e gravitationa l forces
. A t thi s poin t i t wil l continu e t o fal l a t a constan t velocity
. Thi s i s th e termina l velocity
. Fo rspherica l particle s betwee n 3 an d 10 0 micron s an d 0.000 1 < R e < 2 th e applicabl e physica l la w tha t applie s i s Stokes'
. Th e formul a i s state d i n Figur e 6
.

u t= g LD p 2 (P S -P ) 

### 18 n u t Termina l Settlin g Velocit yo f Particl e Unde rActio n

o f Gravity , ft/sec
. gi

_= Loca l Acceleratio n du e t o Gravity,(ft.)/(sec. ) (sec. ) Diamete ro f Spherica l Particle , ft
. P = Flui d Density , Ib.mass/cu.ft
. r 1 = Flui d Viscosity , (lb.mass)/(ft.)(sec. ) D
Figure 6



## VES01700 7

### Th e followin g example s illustrat e th e extreme s i n particl e size s an d velocitie s i n relatio n t o th e Reynold s Number :

Particle s wit h a Reynold s Numbe ro f 1. 7 A n 8 0 micro n particl e i n ai ra t 7 0 ° F an d 14. 7 PSI A wit h a densit yo f 10 0 lb s / cu . ft
. ha s termina l velocit yo f 6 2 FPM
. Whil e a 1 micro n particl e i n ai ra t 7 0 ° F an d 14. 7 PSI A wit h a densit yo f 10 0 lb s I cu . ft
. ha s termina l velocit yo f 5,000 0 FPM
.

Particle s wit h a Reynold s Numbe ro f 3.2 4 X 10- 3 A1 0 micro n particl e i n ai ra t 7 0 ° F an d 14. 7 PSI A wit h a densit yo f 10 0 lb s / cu . ft
. ha s termina l velocit yo f 0.9 6 FPM
. Whil e a particl e les s tha n 1 micro n (1. 9 X 10- 3 t o b e exact ) i n ai ra t 7 0 ° F an d 14. 7 PSI A wit h a densit yo f 10 0 lb s / cu . ft
. ha s termina l velocit yo f 5,000 0 FPM
. 

## Particl e Siz e Particl e siz e i s commonl ydefine d b yit s diamete ri n micrometers , mor e commonl ycalle d microns
. Ho wSmal l i s a Micron ? 

### 1 Micro n i s = 1/25,40 0 o f a n inc h (3.93 7 x10- 5 inches ) 31 8 Huma n Hair s = 1 inc h

Pi n Hea d = 150 0 micron s 84,66 7 Smok e Particle s = 1 inc h 3 3 Smok e Particle s =1 0 micron s

Fo rprope rseparato rdesign , particl e siz e analysi s i s importan t fo rcorrec t equipmen t selection
. A convenien t inde xfo rdeterminatio n o f particl e siz e spectru m i s th e Reynold s number
. Thes e dimensionles s number s provid e a measur e o f th e rati o betwee n viscou s force s an d inertia l forces
. Thre e equation s ar e generall yuse d t o describ e th e actio n o f mechanica l separation , eac h bein g limite d t o definit e particl e spectrum . Thes e equation s hav e th e followin g range s o f particl e spectru m whe n applie d t o wate rdroplet s i n ai ra t atmospheri c conditions : 1
. Newton' s La w ha s a particl e spectru m fro m 15,00 0 t o 100,00 0 microns
. 2
. Th e Intermediat e La w particl e spectru m range s fro m 10 0 t o 15,00 0 microns
. 3
. Stokes ' La w encompasse s particle s fro m 3 t o 10 0 microns
. Belo w 3 micro n particl e size , Stokes'-Cunningha m La w applies
. Belo w 0. 1 micron , Brownia n Movemen t become s dominant
. Brownia n Movemen t i s a rando m motio n o f particle s cause d b y collision s wit h ga s molecules
. Particle s withi n Brownia n Movemen t rang e approac h molecula r size
. Newton' s an d th e Intermediat e La w equation s ar e generall yapplie d t o knoc k ou t drum s an d gravit ysettlin g separators . Wherea s Stokes ' an d Cunningham' s La w equation s appl yt o centrifugal , impingement , an d filterin g typ e separators . Determinatio n o f particl e siz e i n a syste m i s relativel yeas ywit h solids
. However , wit h liquid s i t i s not . Liquid s ar e i n continuou s chang e o f state , subsequentl yparticl e siz e o f liquid s wil l var y dependin g upo n th e sourc e an d natur e o f th e operatio n generatin g th e particula rparticles
. Fo rth e applicabl e physica l la w fo rparticle s i n relatio n t o th e Reynold s Numbe rse e Tabl e 1
.



## VES01700 8Characteristic s O f Disperse d Particle s
ClrlNVliUltlCl

! 

### 1100,00 0 5 2 10,00 0 5
2 

### LOC O 5 1 in .

- 1 cm. - C'lMinorcial E()ui:)mei! ] fol CulliiMion n

r Uenvjvii l o

f Policie s fro

m a Ga s

0. 1 

### 5
2 00 1 

### 5 ! 

### 2 0.03 1 .100A , A—:= Gravit y Settlin g o f Sphere s i n Stil ! Flui

d Spike s o

f Unit Oerraly i n Ai r Diameler . Micoi s 

### 100,00 0 Reynold s

Number 

### L N R e_ 

### 200,000 -
10,00 0

-1,000 -



### -100 - Sphere s o

f Any Densit

y i n Any Fluid

-500 -

* Furnishe

s Averag e Particl e Diameter

, bu tn o Siz e Distribution

] x Siz e Distributio

n ma y b e Obtaine d b y Specia l Calibratio

n Fro m Kineti c Theor y o f Gases : X m = 3p/ p 9



### . R T / n M -1.0 -

-0.1 -

-0.01 - "0.0001 - Law s o f Settlin g

Newton' s La w C = 0.4 4 (Ps-P)

Intermediat

e La w C = 18.5N R ° e 6 0.15 3 g^D. "

f ,0.29^ 0 4

3

Stokes ' La

w C = 24N R e 1 9 l D p <Ps-p ) 1 8 ft ; "t s

Stoke s - Cunningha

m La w

u r K m u t s

K m " 1 + Km e (*T

n ' Critica l Particl e Diamete

r Abov e Whic h La w Wil l Mo t Appl y

D p,crit= K c r 9 L p(fh-f')

K c r= 43. 5 fo r Intermediat

e La w

K C r= 3 3 fo rStokes ' La

w

Th e Cunningha

m Correctio

n o n Sloke s La w Become s importan tfo rParticle s o f Diameter s Unde r 3 Micron

s fo rSettlin g i n Gase s an d Unde r 0.0 1 Micro n fo r Settlin g ; n liquids . Th e Valu e Km e ha s Experimentall

y bee n show n t o li e betwee n 1. 3 an d 2. 3 fo rDifferen

tGases , Particl

e Sizes , an

d Material

s (Wasser

, Physik.Z.,34,257-278[1933Tj . A n Approximat

e Averag e Valu e Base d o n th e Dat a o f Milliko n i s Empiricall

y Give n b y Kme =1.644+0.5S2 e-(0.65 6 Dp/Xm ) Brownia n Movemen

t /"3cRTK m t

( ~ V 3n 2 F ND . Brownia n Movemen

ti s a Rando

m Motio n Superimpose

d upo n th e Gravitationa

l Settlin g Velocit y o f th e Particl e i tBecome s Appreciob

e fo r Particle s unde r 3 Micron

s Diamete

r an d Become

s Entirel y Predominan

t fo rParticle s Unde r 0. 1 Micro n

—0.001 - iMomenclaiure

: (An y Self-Consistan

tSyste m o f Unit s ma y b e Employed ; Englis

h Unit s ar e give n b y wa y o f Example.

)
p cri t ; Overal l dra g Coefficient

, Dimensionles

s

- Diamete r o f Spherica l Particle , ft . = Critica l Particl e Diamete r Abov e Whic h La w wil l No tApply , ft . = Conversio

n Factor , 32.17(lb.mass/l

b Force). ' (ft./sec. ) = Loca l Acce l oratio n du g t o Gravity,(ft)/(sec.

) (sec. ) = Proportionalit

y Factor , Dimensionles

s : Stokes-Cunningha

m Correctio

n Facto r Dimensionles

s = Proportionalit

y Factor , Dimensionles

s = Moiecuia

r Weight , IbJmol e -Numbe r o f Ga s Molecule

s i n a mole , 2.76x10 * Molecules/l

b mote . f

I' s f = Reynold

s Number . Dimensionles

s -Dp f'/^E/ ^ = Ga s Constant

, 1,546(fl-ib.Force)(lb

. mo1e)(°F ) = Time , se c = Absolut e Ga s Temperature

. ° F abs. , D r ° R = Termina l Settlin g Velocit y o f Panicl e Unde r Actio n o f Gravity , ft/sec . = Termina l Settlin g Velocit y o f Particl e a s Calculate d fro m Stokes ' Law , ft./sec . = Mea n Molecula

r Speed , ft./sec . = Averag e Linea rAmplitud

e o f Displacemen

to f Particl e I n Tim e t , ft . = Flui d Density , Ib.mass/cu.ft

. = Tru e Densit y o f Particle , Ib.mass/cu.ft

. = Flui d Viscosity

, (lb.mass)/(ft.)(sec.

) = Mea n Fre e Pat h o f Ga s Molecules

, ft . Characteristics

of dispersed

particles. Table 1 Perry, J. H., Ed., Chemical Engineers

Handbook, 3rd. ed., 1950, McGraw Hill company, Inc.



## VES01700 9

## Particl e Motio n Mechanica l separator s utiliz e particl e motio n i n tw o ways :

• Primar yseparatio n o f solids/liquid s •Carr yof f o f separate d solids/liquid s Al l separator s hav e mor e tha t on e generativ e forc e providin g particl e separation , however , the y ar e typicall yclassifie d b yth e dominan t separatio n proces s - gravit ysettling , impingement , centrifuga l action , coalescing , o rfiltering
. Al l mechanica l separator s rel yo n th e principl e o f impingement
. Impingemen t i s th e actio n o f particle s collidin g wit h othe rparticle s and/o rsurfaces
. Al l mechanica l separator s us e gravit yforc e t o assis t i n th e carr yof f o f separate d solids/liquids
. Thi s forc e i s normall yconsidere d th e maximu m agen t availabl e fo rcarr yof f i n mechanica l typ e separator s wit h th e exceptio n o f cyclon e typ e separators . Ther e ar e fou rbasi c concept s o f mechanica l separation : •Gravit yo rKnoc k

Ou t Drum s •Centrifuga l (Cyclone ) •Impingemen t • Filter s 

## Mechanica l Separato r Limitation s Mechanica l separator s ar e limite d i n primar yseparatio n b ygeometry , b yvelocit yrequire d t o induc e inertia l fields , o rb ypressur e differentia l du e t o dra g losses
. Mechanica l separator s ar e limite d i n carr yof f capabilitie s o f separate d solids/liquid s du e t o re entrainmen t an d creepin g flow
. Re-entrainmen t i s du e t o dra g forc e pullin g solid/liqui d of f surface s t o for m globs/droplet s whic h ar e re-injecte d int o th e ga s stream . Re-entrainmen t (carr yover ) ca n occu ri n al l type s o f separators , an d i n th e cas e o f cyclon e type s i s du e t o a n intens e inne r vorte xcreatin g a velocit yfiel d t o pul l solids/liquid s ou t o f th e drai n sum p are a an d re-injec t th e separate d particulat e int o th e ga s steam . Creepin g solid/liqui d flo w i s cause d b ydra g forc e o n solids/liquid s deposite d o n surface s overcomin g gravit ydrai n force s an d causin g a flo w o f solid/liqui d ou t o f th e separato rint o th e clea n ga s side
. Bot h re-entrainmen t an d creepin g flo w ca n b e eliminate d b ycorrec t sizin g technique s an d produc t design , tha t contro l th e velocit yi n relatio n t o th e flui d density , viscosity , throug h th e separatin g element
. Th e basi c informatio n regardin g particl e formation , physics , motio n an d limitation s hav e bee n presented
. Th e followin g informatio n detail s th e fou rconcept s o f mechanica l separation
. 

## Gravit y o r Knoc k

Ou t Drum s A gravit yo rknockou t dru m typicall yha s th e inle t an d outle t connection s locate d o n th e uppe rportio n o f th e vessel
. Th e forc e use d t o separat e th e solids/liquid s fro m th e ga s i s gravity
. Th e primar y physic s involve d i s th e termina l velocit y ofth e particulate
. I t ca n b e see n tha t th e ga s velocit ymus t b e ver ylo w i n orde r fo rseparatio n t o occur .



## VES01701 0A 

## Centrifuga l Separato r Velocit yi s th e primar yfacto ri n th e performanc e o f a centrifuga l separator . Fo ra give n siz e centrifuga l separator , th e siz e o f th e separate d particulat e i s inversel yproportiona l t o th e squar e roo t o f th e ga s velocity
. Consequently , th e succes s o f a centrifuga l separato ri s dependen t o n th e ga s velocit yobtained
. Th e minimu m particl e siz e t o b e separate d i s dependen t o n th e particulat e viscosity , numbe ro f turn s th e particulat e make s withi n th e separator , an d th e velocit yo f th e ga s a t th e inle t t o th e separator . 

## Impingemen t Separato r A n impingemen t separato ri s i n th e categor yo f separator s tha t provid e target s fo rth e particulat e t o b e intercepted
. Th e wir e mes h separato ran d van e typ e separato rar e tw o o f th e mos t commonl y use d impingemen t separators .

Wire Mesh Separator 

### Th e wir e mes h separato rconsist s o f wir e knitte d int o a pa d havin g

a numbe ro f unaligne d isometrica l openings
. I t ha s 97 % t o 99 % fre e void s an d collect s th e particle s primaril yb yimpingement
. Th e principa l o f operatio n o f a wir e mes h pa d i s chang e o f direction
. Th e ga s flowin g throug h th e pa d i s force d t o chang e directio n a numbe ro f times
. Centrifuga l actio n i s t o a minimum
. Impingement , therefore , i s th e primar yseparatio n mechanism
. A liqui d particl e strikin g th e meta l surface s o f a mes h pad , flow s downwar d wher e adjacen t wire s provid e capillar yspace . A t thi s point , liqui d collect s an d continue s t o flo w downward
. Surfac e tensio n tend s t o hol d thi s dro p o n th e lowe rbas e o f th e pa d unti l the yar e larg e enoug h fo rth e downwar d forc e o f gravit yt o excee d tha t o f th e upwar d ga s velocit yan d surfac e tension
. I n a mes h pa d separato rth e impingemen t efficienc yfall s of f rapidl y a t lo w velocitie s becaus e th e droplet s wil l ten d t o drif t betwee n th e wires
. A t hig h velocities , th e elemen t tend s t o flood
. Liqui d canno t flo w downwar d agains t th e increase d upwar d ga s velocit y forc e an d therefor e accumulates
. A s th e void s becom e ful l o f liquid , a portio n i s re-entraine d an d discharge s wit h th e outle t gas . Th e wir e mes h separato ri s considere d primaril ya liqui d separator ; dirt , solids , o rver yviscou s liquid s o f stick ynatur e wil l plu g th e void s resultin g i n poo rperformance
.

Pocke t 

### Van e typ e separator s consis t o f labyrint h for m o f paralle l meta l sheet s wit h pocket s t o collec t separate d moisture
. Th e ga s betwee n plate s i s agitate d an d ha s t o chang e directio n a numbe ro f times
. Som e degre e o f centrifuga l actio n i s introduce d a s th e ga s change s direction
. Th e heavie r particle s the n ar e throw n t o th e outsid e an d ar e caugh t i n th e drai n pockets
.



## VES01701 1

### Van e typ e separator s fal l int o tw o categorie s - pocke t styl e an d hoo k style
. Van e separator s whic h incorporat e corrugation s o rhook s protrudin g int o th e flo w pat h creat e pressur e dro p an d flo w turbulenc e resultin g i n potentia l re-entrainmen t o f separate d liquid
. Flo w withi n pocke t typ e van e separator s i s sinusoida l an d separatio n i s accomplishe d b ybot h impingemen t an d coalescence
. Eve n thoug h th e hoo k styl e incorporate s th e sam e impingemen t separatio n characteristics , th e pocke t styl e van e separato raccomplishe s th e separatio n functio n a t highe r velocitie s withou t re-entrainment
. A van e typ e separato rwit h pocket s function s a s follows ; whe n liqui d lade n ga s vapo rapproache s th e van e plate s i t i s force d t o chang e direction , movin g th e liqui d droplet s t o th e plat e wall s convertin g th e liqui d t o shee t flo w i n wha t i s calle d coalescence
. Thi s mechanis m i s a functio n o f th e pat h distanc e an d th e fre e strea m velocity
. Liqui d shee t flo w approache s th e van e pocke t wher e i t i s collecte d an d remove d fro m th e ga s strea m an d ultimatel ydrain s t o th e liquid^^ y holdin g sum p du e t o gravity
. Sizin g o f a van e typ e separato ri s dependen t o n relativ e densit yo f th e liqui d an d gas , relativ e siz e o f liqui d droplets , an d relativ e weigh t rati o o f th e liqui d t o ga s stream . I n mos t instance s th e maximu m liqui d t o ga s weigh t rati o o f van e typ e separator s i s 10%
. I n an ycase , impingemen t typ e separator s tha t emplo ywir e mes h o rvan e typ e element s ar e limite d t o liqui d particl e separation , ultimatel y dir t o rsoli d particulate , an d viscou s liquid s wil l plu g th e void s i n mes h pad s o rpocket s i n van e separator s resultin g i n poo r performance
. Vane Type Separator

Van e Pac k Filter Separator 

## Filte r Separato r Filte rseparator s ar e designe d t o provid e optimu m performanc e i n mechanica l separation , an d ar e use d i n separatin g aerosol s an d soli d particles
. Th e remova l o f solid s i s accomplishe d b yinterceptio n ofth e particle s an d it s efficienc yi s dependen t o n th e dept h o f th e filte rmedi a densit yan d siz e o f th e fiber
. Th e primar yfunctio n o f a filte rseparato ri s th e remova l o f smal l liqui d particle s tha t wil l hav e a detrimenta l effec t o n downstrea m equipment
. Mechanica l separator s suc h a s vanes , centrifuga l o rwir e mesh , ar e effectiv e fo rremova l o f particle s abov e 6 microns , wher e th e liqui d t o ga s weigh t rati o i s greate rtha n 1 % b y weight , ligh t liqui d load s (les s than1% ) characteristicall yhav e particl e siz e distributio n o f les s tha n 6 micron s an d therefore , mechanica l separator s wit h vane , centrifugal , o rwir e mes h element s ar e no t effective
. T o collec t liqui d particle s les s tha n 6 micro n requir e particl e conditioning
. On e o f th e mos t practica l method s o f particl e conditionin g i s coalescence
. Solid s

Hollo wFilte r Cor e 

### Hii'i' i i HiiiiMUHi

n ti'ii m i iimmHJuiiJiHiiiiijiHiiuu m 

# iliiiiillf^ll l
F/7fe r SeparatorCartridge Filter


## VES01701 2

### Coalescenc e i s th e mechanis m wher e smal l droplet s ar e agglomerate d o n a fibe rma t o rsurface ,

an d form s a continuou s liqui d fil m whic h periodicall yshear s an d release s larg e droplet s bac k int o th e ga s stream . Th e siz e o f thes e droplet s depen d o n th e surfac e tensio n an d viscosit yo f th e liqui d an d th e velocit yo f th e ga s relativ e t o th e liquid
. Th e filte rseparato ruse s cylindrica l coalescin g element s fo rparticl e conditioning
. Th e desig n o f thes e element s i s th e mos t importan t componen t i n th e desig n o f a filte rseparator . Th e firs t ste p i n th e desig n o f th e element s i s a n analysi s o f th e liqui d particl e siz e an d concentratio n i n th e ga s stream . Ther e ar e thre e mechanism s o f particl e collectio n t o b e considere d i n th e desig n o f filte relement s fo rmis t elimination
. Thes e ar e inertia l impaction , diffusion , an d direc t interception
.

Inertia l impactio n (impingement ) i s th e aerodynami c behavio ro f a particl e withi n th e fibrou s medi a o f th e filter
. I f th e particl e ha s sufficien t inerti a an d lo w enoug h surfac e dra g characteristics , i t wil l b e attracte d an d hel d t o fibe ri n th e medi a du e t o Va n De rWaal s Force
.



# DIFFUSIO N

A thir d mechanis m i s tha t o f direc t interceptio n (straining)
. A particl e o f larg e enoug h size , relativ e t o th e siz e ofth e fibe rwil l b e collecte d eve n i f i t ha s n o mas s an d ca n follo w ga s flo w path
. Fo rthi s reaso n fibe rdiamete ran d densit yar e a majo rconsideratio n i n th e desig n o f filte relements
. 

# IMPINGEMEN T

Diffusio n i s th e rando m movemen t o f particle s calle d Brownia n Motion
. Brownia n Motio n wil l manifes t itsel f a s a wobbling , errati c motio n o f th e particle s abou t th e stead yaerodynami c ga s path
. Thi s motio n woul d no t o f itsel f resul t i n additiona l collectio n o f particle s b yfiber s i f th e particl e concentratio n wer e everywher e identical
. Bu t sinc e th e motio n i s totall yrandom , th e transfe ro f particle s acros s an ysurfac e nea ra fibe rwil l b e proportiona l t o th e concentratio n o n opposit e side s o f tha t surface
. I t ca n b e show n tha t ther e i s a ne t transfe ro f particle s acros s a surfac e an d tha t thi s transfe r i s i n th e directio n o f th e fibe rsurfac e itself
. Th e rat e a t whic h suc h transfe rtake s plac e i s proportiona l t o a diffusio n coefficient
.



# STRAININ G

VES01701 3

### Th e combine d propertie s o f inertia l impactio n (impingement) , diffusio n an d direc t interceptio n (straining ) enabl e u s t o stat e qualitatively , a t least , ho w aeroso l (suspende d particle s i n gases ) filtratio n wil l b e effected
. Th e grap h depict s th e effec t which , woul d resul t i f aerodynami c collectio n alon e wer e operativ e an d i f Brownia n diffusio n alon e wer e operative
. Th e to p curv e depict s th e su m o f thes e tw o effects
. I t i s apparen t tha t th e Brownia n diffusio n curv e fall s towar d zer o fo rparticle s approachin g molecula rsiz e (a n aeroso l filte rdoe s no t filte rou t gases)
. I n addition , i t i s no t a t al l unusua l fo rfilte refficienc yt o dro p somewha t towar d zer o fo rlarg e particle s becaus e o f thei rpoo rretentio n afte rcaptur e b y som e filte r media
. Th e mer e transpor t o f particle s t o th e fibe r surfac e i s no t sufficien t o f itsel f t o ensur e thei r collection
. The yals o hav e t o remai n o n th e fibe r surface
. 

# t \ J



# \ v A 

# \

If * PARTICL E SIZ E O R VELOCIT Y 1

0 -DIFFUSIO N EFFICIENC Y

-IMPACTIO N EFFICIENC Y

r-TOTA L EFFICIENC Y

-POIN T O F MINIMU M EFFICIENC Y 

### Blow-of f i s th e ter m referrin g t o th e proces s o f re-entrainmen t ofth e liqui d collecte d b y th e fibrou s pa d i n th e ga s flowin g fro m th e pad
. I t i s effecte d b y severa l factor s - inle t aeroso l concentration , ga s flo w velocity , viscositie s an d densitie s o f th e ga s an d liquid , pa d surfac e are a an d porosit y an d interfacia l an d surfac e tensio n forces
. Blow-of f efficienc yi s a functio n o f th e velocit yo f th e ga s an d th e velocit yo f th e liqui d throug h th e fiber
. A t lo w velocities , les s tha n 6 fee t pe rminute , th e efficienc yo f collectio n o f th e filte r decrease s until th e effec t o f th e diffusio n mechanis m become s apparen t whereb y th e smalle rparticles , b y thei rrando m motion , wil l agai n b e collected
. A t th e blow-of f velocit ylarg e droplet s ar e shearin g awa yfro m th e fil m o f collecte d liquid s o n th e filte rfibers
. Th e smal l droplet s appea ragai n a s a secondar y produc t o f th e large rdrople t formation
. Thi s then , i s a velocit yregio n o f lo w filtratio n efficiency
. I f th e filte ri s t o b e use d a s a mis t eliminato ri t shoul d b e designe d s o tha t th e aeroso l velocit y throug h th e filte ri s les s tha n th e critica l blow-of f velocity
. I f however , th e filte ri s t o b e use d a s a n agglomerato relemen t th e velocit ymus t b e greate rtha n th e critica l blow-of f velocity
. Th e idea l operatin g condition s o f a n agglomerato rfilter , i s a t a velocit yjus t beyon d th e initia l blow-of f velocity
. A t thi s conditio n mor e o f th e smalle rdroplet s enterin g th e pa d woul d b e impacte d becaus e o f th e highe rvelocit yan d th e droplet s leavin g th e pa d ar e a t it s large rsize
. A t highe r velocitie s mor e droplet s wil l b e impacte d bu t th e blow-of f droplet s wil l b e smalle ri n size
. A ver yimportan t us e o f th e blow-of f characteristic s o f fibrou s ma t typ e eliminato relemen t i s tha t o f particl e agglomeration
. Fiberglas s o rsimila rmaterial s wit h fin e fiber s ca n b e use d t o collec t th e ver ysmal l aeroso l particle s a t aeroso l velocit ywhic h wil l produc e blow-of f drainag e o f th e collecte d liqui d fro m th e pad
. Th e large rdroplet s ca n the n b e collecte d b y anothe rmechanica l separato rsuc h a s vane , wir e mes h o ra centrifuga l unit
.



## VES01701 4

### Hydrocarbo i

0.O0 4

O.O0 3

sp . gr .

1. 0 0. 9 0. 8 0. 7 0. 6 -400 .55 -

-30 0 -20

0 -10

0 

### i i TKi .

10 0 20

0 30

0 40

0 Temperatur e ° F -L..55 - 50 0 60

0 70

0 80

0 90 0 100 0 From Gas Processors

Suppiers

Association, Tulsa


## VES01701 5PROPERT Y Propertie s at 14.69 6 PSI A arti 6 0 F

MOLECULAR ! WEIGH T I DENSIT Y | VISCOSIT Y (Centipoises ) COMPOUN D SYMBO L j MOLECULAR ! WEIGH T I LIQUI D LIQUID TEM P

( 1 ht/F t ^

1 'COEFFICIEN

T
1 ' O F DENSIT Y G A S (Lbs/Ft 3 ) GASSPECFI C

GRAVIT Y AIR=1. 0 I

LIQUI D G A S AI R 28.96 6 - 0.0764 0 1.000

0 0.17

2 at-314° F 0.0181 7 WATE R 18.01 6 62.36 5
- - - - 1.140 4 0.0125

5 at212 T AMMONI A NH 3 17.03 2 38.50

2 a t 106. 3 psi a - 0.0449 2 0.588

0 0.27

6 a t -40° F 0.0096

8 ARGO N A 39.94 4 - - 0.1053 0 1.378

3 — 0.0219 0 CARBO N MONOXID E C O 28.01 0 - - 0.0738 8 0.967

0 „ 0.0172 3 CARBO N DIOXID E c o 2 44.01 0 50.88 2 a t 74 1 psi a - 0.1160 8 1.519

4 0.07

7 a t 107. 6 psi a 0.0146

0 CHLORIN E C1 2 70.91 4 88.71 9 a t 85. 9 psi a 01870 4 2.448

2 0.38

5 a t 32° F 0.0130

9 HELIU M H e 4.00

3 - - 0.0105 5 0.138

1 „ 0.0192 3 HYDROGE N H 2 2.01 6 - 0.0053 2 0.069

6 0.01 1 at-434° F 0.0086 6 HYDROGE N CHLORID E HC 1 36.46

5 53.31 1 a

t 42 7 psi a - 0.0968 8 1.26

8 0.0140 2 HYDROGE N SULFID E H 2 S 34.07 6 49.22

2 a t 23 5 psi a — 0.0898 8 1.176

4

_ _ 0.0123 4 METHYLCHLORID E C H 3 C 1 50.4 9 61.

9 al-13" F - 0.1329 2 1.739

8 — 0.0104 3 NITROGE N N 2 28.01 6 - - 0.0738 9 0-967

2

- 0.0172 8 OXYGE N ° 2 32.00 0 - - 0.084 4 1.104

7

- 0.0197 1 SULFUR DIOXID E so 2 64.06 0 86.92

3 a t 40. 6 psia - 0.1689 7 2.211 6 0.393 6 a t 32" F 0.0123

0 METHAN E CH 4 16.04 2 - - 0.0424 0 0.55

5 — 0.0107 3 ETHAN E C 2 H 6 30.06 8 - - 0.0799 1 1.04

6
_ 0.0089 6 PROPAN E C 3 H 8 44.09 4 31.598atSat.Pr . 0.0017 1 0.1181 9 1.54 7 0 10

8 0.007

8 n - BUTAN E C 4 H 1 0 58.12 0 36.37

8 a t Sat.Pr . 0.0011 1 0.1582 2 2.07

1 0.18

0 0.007

3 n - PENTAN E C 5 H 1 2 72.14 6 39.2

9 0.0008

6 0.1902

8 2.490

6 0.25

1 0.0065

6 n-HEXAN E C 6 H 1 4 86.17 2 41.34

5 0.0007

7 0.2272

8 2.974

9 0.33

7 - n - HEPTAN E C 7 H 1 6 100.19 8 42.85

1 0.0006

9 0.2642

8 3.459

1 0-42

5 - n-OCTAN E C 8 H 1 8 114.22 4 44.01 0 0.0006 3 0.3012

6 3.943

2 0.55

5 0.0067

5 a t 213° F n - NONAN E C G H 2 0 128.25 0 44.94

2 0.0005

9 0.3382

6 4.427

5 0-67

6 O .0067

5 at212° F n-DECAN E C 1F) H 2 2 142.27 6 45.73

6 0.0005

5 0.3752

6 4.911 8 0.9 2 a t 68 " F - CYCLOPENTAN E C 5 H 1 0 70.13 0 46.73

7 0.00073

0 0.1849

7 2-421 1 0.49 3 a t 56° F - METHYLCYCLOPENTAN E C 6 H 1 2 84.15 6 46.92

7 0.00069

3 0.2219

6 2.905

3 — - ETHEN E (ETHYLENE ) C 2 H 4 28.05 2 21.2

5 a l 32 ° F
- 0.0739 9 0.968

4 0-0

7 a t 32 ° F 0.009

8 PROPEN E c 3 H f i 42.07 8 32.46

5 a t Sat . Pr . 0.0017

7 0.1109

8 1.452

6

- - 1-BUTEN E C 4 H R 56.10 4 37.41 0 atSal.Pr . 0.0011 3 0.1479 7 1.936

8 0.1 6 0.007 4 1 - PENTEN E c S H m 70.13 0 40.22

3 0.0008

7 0.1849

6 2.421 0 — 1,2 - BUTADIEN E C 4 H 6 54.08 8 40.96

3 a t Sat.Pr . 0.0011 4 0.1426 6 1.867

3

- - ETHYN E (ACETYLENE ) ^2^ 2 26.03 6 38.28

5 a t 57 8 psi a - 0.0686 7 0.898

8

- O.0093 5 a t 32° F BENZEN E C 6 H 6 78.10 8 55.10

1 0.00068

6 0.2060

1 2.696

5 0-70

0 0.0073

8 a t 57.6° F TOLUEN E C 7 H f i 92.13 4 54.31 0 0.00059 2 0.2430

1 3.180

8 0.62

4 - STYREN E C R H 8 104.14 4 56.75

6 0.00058

4 3.2746

9 3.595

4

- ISOPROP L BENZEN E C A H 1 ? 120.18 6 53.96

7 0.00055

0 3.3170

0 4.149

2

- - ACETON E C^H r O 58.0 8 49.

4
- - - 0.33 6 O .0093 1 at212° F ETHY L ACETAT E C 4 H R° ? 88.1 0 56. 6 - - - 0.47 1 O.0068

4 a t 32° F ETHY L ALCOHO L C ,H K 0 46.06 9 49.51 3 - 0.1215 1 1.590

5 1.22

0 O.010

8 at212° F METHY L ALCOHO L CH 4 0 32.04 2 49.64

8

- 0.8451 4 1.106 2 0.62

0 0.0135at152.2° F n-PROP L ALCOHO L C a H fl 0 60.0 9 50.

2 at68° F

- - - 2.49 4 O.009

3 at212° F FURFURA L C,H 4 0 2 96.0 8 74.7
- - - - 1.4 9 a t 77 ° F - MONOETHANOLAMIN E (MEA ) C 2 H 7 N 0 61.0

8 63.5
- - - - 3 7 ETHYLEN E GLYCO L C 2 H 6° 2 62.0 7 69,6 0.0003 9 — 2 3

- DIETHYLEN E GLYCO L C 4 H 10 U 3 106.1 2 70. 0 0.0004

1 4 7

- TRIETHYLEN E GLYCO L C 6 H 14° 4 150.1 7 70. 4 0.0004

4 — — 5 1

- TETRAETHYLEN E GLYCO L C 8 H 18° 5 194 2 70.

5 0.0004

3 — 6 0

- PROPYLEN E GLYCO L C 3 H 8° 2 76.0 9 64.9 0.00042 5 — — 7 7

- - DIPROPYLEN E GLYCO L C 6 H 14° 3 134.1 7 64. 2 0.000

4 — — 15 0

- TRIPROPYLEN E GLYCO L C 9 H 20° 4 192. 3 64. 1 0.0004 8

- 10 0

- TYPICA L CYLINDE R
- - - 56. 9

- - — — 173 5

- LUBRICATIN G OIL . (DTE-105)



## VES01701 6

### 1ABL E unles s Otherwis e Note d

CRITICA L CONSTANT S REDUCE D CONDITION S Freezin g Poin t a t 14.69 6 PSI A ("F

) Boilin g Surfac e Tensio n i (Dynes/Cm. ) RATI O O F TEMP - ERATUR E T C CF ) PRESSUR E

P c (PSIA

) COMPRESSBUT

Y FACTO R (CRITICAL) T 5 (60°F ) P S (14.596 ) P C Freezin g

Poin t a t 14.69 6 PSI A ("F

) Poin t a t 14.69 6 PSI A ("F

) LIQUI D T O

VAPO R LIQUI D T O

AI R SPECIFI C

HEAT S FO R GA S -221. 3 547 0.2 9 2.180 0.027 - -317. 7 1.4 0 705. 4 320

6 0.232 0.446 0 Q0 5 3

2 21 2 

### - 73.4 2 - 271. 4 165

7 0.25 0.71 1 0.009 -107. 9 -28. 1 2 3 a t52 ° F 1.3 1 -187, 7 705 0,2 9 1.91 1 0.02 1 -308. 6 -302, 3 - - 1.6 7 -21 8 51 0 0.2 9 2.150 0.029 -340. 6 -313. 6 9,8at-315.4° F 1.4 0 88. 0 107

3 0.2 9 0.949 0.01 4 

### - -109. 3 1. 2 at68° F 1.3 0 29 1 112

0 0.2 9 069 2 0,01 3 -150. 9 30, 3 18.at.68°F...... . 1.3 7 -450. 2 33. 2 . . . 54.705 0.44 3 -458 a

t38 2 psi a -45 2

_ . 1.6 6 -399. 8 18

8 0.2 9 8.67 6 0.078 -434. 4 -422. 9 1.9 1 at-423° F 1.41 124. 5 119

9 0.2 9 0.89 0 0.01 2 -173. 6 -12 1

_ _ . .66a t68.°.F . 1.4 1 212. 7 130

6 JL29
_ 0.77 3 0.01 1 -121. 9 -76. 5

_ _ 1.3 2 289. 6 96 8 0.2 7 0.69 4 0.01 5 -126. 1 -10. 3 

### - 16.2 at68° F 1.2 0 -232. 8 492 0.2 9 2.290 0.03 0 -345. 6 -320. 4 10.5 3 at-333.4° F 1.4 0 -181. 8 730 0.2 9 1.87 0 0.02

0 -361. 1 -297. 4 13. 2 at-297.4° F 1.4 0 31 5 114

2 0.2 9 0.67 1 0.01 3 -98. 9 1 4 

### - 1.2 5 -116. 5 673. 1 0.2 9 1.514 0.02 2 -296. 5 258. 7 2. 8 a t-150° F 1.3 1 90. 1 708. 3 0.28 8 0.945 0.02 1 -297. 9 -127. 5 1. 6 1.1 9 206. 3 617.4 0.278 0.78 0 0.02

4 -305. 8 -43. 7 7, 8 1.1 4 305. 6 550. 7 0.27 4 0.679 0.02 7 -217. 0 31. 1 13. 1 1.0 9 385. 9 489. 5 0.28 6 0.61 5 0.03 0 -201. 6 96. 9 16. 6 - 454. 5 439. 7 0.26 4 0.568 0.03 3 -139. 6 155. 7 8,9 18.4 3 a l 68° F - 512. 6 396. 9 0.260 0.535 0.037 -131. 1 209. 2 20. 8 

### - 565. 2 362. 1 0.25 6 0.50 7 0.04 1 -70. 2 258. 2 21. 8 ai 68° F - 61 3 34

5 0.25 0 0.48 4 0.04

3 -64. 4 303. 4 - - 65 5 32

0 0.24 6 0.466 0.04 6 -21. 5 345. 2 — - 461. 5 654. 7 3 27 6 0.56 4 0.02

2 -137. 0 120. 7 -_ 499. 3 549. 1 0.27 3 0.54

2 0.027 -224. 4 161. 3 - 49. 8 742. 1 0.26 9 1.02 0 0.020 -272. 5 -154. 7 •, : a!32° F 1.2 4 197.4 667 0.27 4 0.79 1 0.02 2 -301. 5 -53. 9 1.1 5 295. 6 58

3 0.27

7 0.688 0.025... . -301. 6 20. 7 13. 5 1.1 1 39 4 586 0.27 0.609 0.025 -265. 4 86. 0 - 33 9 65

3 0.27 0.65 1 0.02 3 -213. 3 50. 5 - 1.1 2 97. 4 90

5 0.27

4 0.93

3 0.01 6 -11 4 -11 9 - 1.2 4 55 3 71 4 0.27 4 0.51 3 0.02 1 42. 0 176. 2 28.8 9 a t68° F 28.8 5 a

t68° F - 609. 5 61 1 0.260 0.486 0.024 -139. 0 231. 1 28. 5 a t68° F - - 706 580 0.27 0.446 0.025 -23. 1 293. 4 _ 32.1 4 a t66" F - 68 5 47

3 0.27 0.45 4 0.03 1 -140. 9 306. 3 - - 45 5 690 0.2 5 0.568 0.02 1 -13 9 -133 23. 7 a t68" F 23.7 a l 68° F 

### - 482. 2 555 0.25 0.552 0.02 6 -118.4 17 1 „ 23, 9 a t68° F - 469. 6 927 0.25 0.55 9 0.01 6 -179. 1 173. 3 22.7 5 a t68" F 2

2 a t77° F 

### - 464 115

7 0.25 0.56 3 0.01 3 -14 4 148. 1 20.1 4 a t122" F 22.6 1 a

t68° F - 506. 7 73

4 0,25 0.53 8 0.02 0 -196. 6 20 7 23.7 8 a l 68° F -

- - - — -33. 7 323. 3 43. 5 a t68° F 43. 5 a

t68° F -

- 

### - - 

### - 50. 9 34 2 - - 

### -

- - - 

### - 8 387. 1 4 7 at77° F 47. 7 a t68° F

- - 

### - - - ~ 1 7 472. 6 4 4 at77" F

-



### - - - 

### - - 

### - 1 9 545. 9 45at77° F

- —



### - - - 

### - - 22 597. 2 45 a t77° F



### - —



### - - - - - - - — 36 9 3 6 a t77° F

-
~ - 

### - - 

## - - 447. 8 3 3 at77° F


### -

- 

### - - - 

### - ~ 514. 4 3 4 a t77° F

-

- - - - - - 

### - ~



## VES01701 7Reference s : "Chemical

Engineers

Handbook", Perry , R
. H. , Do n W
. Green , 7th. ed., © 1997, McGraw

Hill Company, Inc. "Engineering

Thermodynamics"

Franci s F
. Huang , ©1976, Macmillan Publishing

Co. Inc. "Handbook

of Separation

Techniques

for Chemical

Engineers", Phili p A Schweitzer , 3rd ed, ©1997

McGraw

Hill Company, Inc. "Fundamentals

of Fluid Mechanics", Bruc e R
. IVIunson , Donal d F
. Young , Theodor e H
. Okiishi , 4th ed, ©2002

John Wiley & Sons, Inc. "Gas Engineers

Handbook", 1st

ed, ©1965

Industrial

Press Inc. "Petroleum

Fluid Flow Systems", O.W
. Boyd , 1sted., ©1983, Campbell Petroleum

Series "Separation

Handbook", E
. J
. Halter , 1st ed., ©1966, Burgess Manning

Company "Applied Process

Design", Ernes t E
. Ludwig , Volume 1, 3rd

ed., Gulf

Publishing

Company "Engineering

Data Book", Ga s Processor s Supplier s Association , Volumes 1 and 2, 11th

ed., ©1998, Gas

Processors Suppliers

Association. "Flow of Fluids", Engineerin g Department , Cran e Valves , ©1988, Crane Co. 

# Muelle r Environmenta l Designs , Inc . 760 7 Wrigh t Roa d Houston , Texa s 7704 1 713-465-099 5 Fa x713-465-099 7 E-Mail : MUELLER-ENVIRON@worldnet.att.ne t www.muellerenvironmental.co m 200-05 9



## VES01701 8

# VES017019-017201.pd f

# A n Investigatio n of th e Particl e Dynamic

s o f a Multi-componen

tSoli d Phas

e in a Dilut

e Phas e Pneumati

c Conveying Syste

m

Yon g L u

Institut e fo r Material s an d Processe s Schoo l o f

Engineerin g an d Electronic s

Thesi s submitte d fo r th e degre e o f Docto r o f

Philosoph y Th e Universit y o f

Edinburg h Marc h 0 9

# Abstrac t

I n orde r t o mitigat e the ris k

o f globa l warmin g b y reducin g C0 2emissions , the co-firin g technique , burnin g pulverize dcoa l an dgranula r biomas s together

i n conventiona l pulverise dfue l powe r statio n boilers , ha s bee n advocate dt o generat

e "greener " electricit y t o satisf y energ y deman dwhil e continuin g t o utiliz e existin g ric h coa l resources . A majo r proble mi s controllabl y distributin g fue l mixture s o f pulverize dcoa l an dgranula r biomas s i n acommo n pipeline , thu s savin g muc h investment . Thi s i s stil l unde r developmen t

i n man y co-firin g studies . Thi s researc h int o particl e dynamic s i n pip e flo w wa s undertake n i n orde r t o addres s the proble mo f controllabl e distributio n i n co-firin g technique s an dgai n an improve dunderstandin g o f pneumati c conveyin g mechanisms . Th e objective s o f

thi s researc h were , firstly, t o numericall y evaluat e the influenc e o f variou s factor s o n the behaviou r o f particle s o f

th e differen t

material s i n ahorizonta l pip e gas-soli dflow , secondly , t o develo p an extende dtechniqu e o f Lase r Dopple r Anemometr y i n order

t o detennin e cross-sectiona l characteristic s o f th e soli dphas e flow i n the horizonta l an dvertica l leg s o f a pneumati c conveyin g system , and , thirdly , t o develo p anove l imagin g syste mfo r visualizin g particl e trajectorie s b y usin g ahig h definitio n camcorde r o n across-sectio n illuminate db y a whit e haloge n ligh t

sheet . Finally , acompariso n wa s mad e o f cross-sectiona l flo w characteristic s establishe db y experiment s an dthos e simulate db y usin g acommercia l Computationa l Flui d Dynamic s cod e (Fluent ) an dth e couplin g calculation s o f Fluen t & EDE M ( acommercia l cod e o f Discret e Elemen t

Method ) respectively . Particl e dynami c behaviou r o f th e soli dphas e i n adilut e horizonta l pip e flo w wa s investigate d numericall y b y usin g the Discret e Phase Mode l (DPM ) i n Fluen t 6 .2 .16 . Th e numerica l result s indicat e tha

t th e Saffina n forc e play s an importan t rol e i n re-suspendin g particle s a t th e lowe r pip e boundary an dtha

t thre e critica l parameter s ofth e critica l air : conveyin g velocity , the critica l particl e siz e an dthe critica l pip e roughness , exis t i n pneumati c conveyin g systems . Th e Stoke s numbe r ca n b e use das asimilarit y criterio n t o classif y th e dimensionles s mea n particl e velocit y o f the differen t

material s i n the full y develope dregion . A n extende dLase r

Dopple r Anemometr y (LDA ) techniqu e ha s been develope dt o measur e th e distribution s o f

particl e velocitie s an dparticl e numbe r ove r awhol e pip e cros s sectio n i n adilut e pneumati c conveyin g system . Th e first extensio n concentrate s o n atransfor mmatri x fo r predictin g the refracte dlase r beams ' crossin g poin t i n apip e accordin g t

o th e shif

t coordinat e o f th e 3 D computer-controlle dtravers e syste mo n whic h th e probe s o f the LD A syste mwere



## VES01702 0mounted . Anothe r par t focusse do n the prope r samplin g rate o f

LD A fo r

measurement s o n the gas-soli dpip e flo w wit h polydispersin g particles . A suitabl e LD A samplin g rat e shoul densur

e tha t enoug h dat

ai s recorde di n th e measurement interva l t o precisel y calculat e the particl e mean velocit y o r

other statistica l value s a

t every sampl e point . Th e present study explore s the methodolog y as wel l as fundamental s o f measurement s o f

th e loca l instantaneou s density o f particle s as aprimary standardusin g alase r facility . Th e extende dLD A techniqu e ha s als o bee n applie dt o quantitativel y investigat e particl e dynami c behaviou r

i n the horizonta l an dvertica l pipe s o f adilut e pneumati c conveyin g system . Thre e kind s o f glas s bead s wer e selecte dt o simulat e th e pulverize dcoa l an dbiomas s pellet s transporte d i n adilut e pneumati c conveyin g system . Detaile dinformatio n o n the cross-sectiona l spatia l distribution s o f

th e axia l particl e velocit y an dparticl e numbe r rate i s reported . I n th e horizonta l pip e section , experimenta l dat ao n aserie s o f

cross-section s clearl y illustrat e tw o unifor mfluid pattern s o f

soli dphase : an annula

r structure describin g the cross-sectiona l distributio n o f the axia l particl e velocit y an dastratifie dconfiguratio n describin g particl e numbe r rate . I n the vertica l pip e downstreamo f

an elbo w R/D=1.3 , ahorseshoe-shape dfeature , whic h show s that th e axia l particl e velocit y i s highes t i n wal l region s o f

the pip e o n th e outsid e ofth e ben dfo r al l thre e type s o f glas s bead s o n the sectio n OD clos e t o the elbo w outlet . Th e development s o f cross-sectiona l distribution s o f

particl e numbe r

rat e indicat e tha

t th e horseshoe-shape dfeature o f particl e flow patter n i s rapidl y disperse dfo r particle s wit h hig h inertia . A vide o & imag e processin g syste mha s bee n buil t usin g ahig h definitio n camcorde r an daligh t shee t from asourc e consistin g o f ahaloge n lamp . A set

o f vide o an dimag e processin g algorithm s ha s bee n develope dt

o extrac t particl e informatio n fro meac h frame i n avideo . Th e experimenta l result s sugges t

tha t th e gas-soli dflo w i n adilut e pneumati c conveyin g syste mi s alway s heterogeneou s an dunsteady . Th e parameter o f particl e mas s mean siz e i s superio r t o particl e numbe r mean siz e fo r

statisticall y describin g th e unsteady propertie s o f gas-soli dpip e flow . I

t i s als o demonstrate dtha

t the loca l dat ao f

particl e numbe r

rat e o r concentratio n ar

e represente db y a stratifie dstructure o f

the flow pattern ove r

ahorizonta l pip e cross-section . Finally , comparison s o f numericall y predicate dflow pattern s an dexperimenta l one s sho w tha t ther e i s reasonabl e agreement a t pip e cross-section s locate da t horizonta l position s les s than hal f the produc t

o f particl e mean velocit y an dmean fre e fal l tim e i n the pip e fromth e particl e inlet . Furthe r away fromth

e inlet , th e numerica l result s sho w flow pattern s whic h ar e increasingl y divergen t

fromthe experimenta l results alon g th e pip e i n th e directio n o f flow. Thi s discrepanc y indicate s tha

t particles ' spatia l distributio n i n the pip e i s no t accuratel y predicte db y the Discret e Phas e Mode l o r

Fluen t couple dwit h EDEM .



### i i



## VES01702 1

# Declaratio n

I declar e tha tthi s thesi s describe

s wor k carried ou

tin th e Institut e fo r Material

s an d Processes, Schoo

l o f Engineerin

g an d Electronics , th

e Universit

y o f Edinburgh . I

tis th e origina l wor k o f th e autho r excep twher e otherwis

e stated . Thi s thesi

s ha s bee n compose d by myself

an d wa s no tsubmitte

d i n an y for m a tanothe r university .

Signe d

Yon g L u Edinburgh, 1

7 March 200

9

ii i



## VES01702 2

# Acknowledgement s

I woul d lik

e to expres s my deepes t gratitud e t o m y supervisors , Dr . Donal d H . Glas s an d Professo r Willia m J . Easson . Thei r dedicatio n an d enthusias m t o scientifi c research , thei r brillian t ide a an d encouragemen t were essentia l t o buil t u p thi s thesis . Withou t thei r preciou s help , I woul d hav e neve r com e to Edinburg h an d starte d m y Ph.D . I als o wan t t o than k

Dr . Marti n Crapper , wh o ha s advise d an d guide d m e fo r numerica l simulation s by usin g EDEM . Her e I a m gratefu l to DE M Solution s Limited , Edinburg h fo r thei r assistanc e wit h thi s numerica l work . Man y thank

s t o Mr . Bobby Hogg , Mr . Nei l Woo d an d Mr . Roby , wh o gav e muc h help s o f providin g technica l suppor t fo r experiments . An d als o man y thank s t o my friend s nea r an d fa r fo r thei r friendshi p an d th e happ y moments w e share d together , especiall y to Dr . Ha o Wan g wit h who m I share d th e fla t an d encourage d eac h othe r i n pas t tw o years . I a m extremel y gratefu l to th e committee of 200 5 UK/Chin a Yout h Scholarship s fo r Excellence , Universit

y o f Edinburg h an d Southeas t Universit y fo r th e financia l support . Thes e support s have mad e m y stud y a t Edinburg h possible . Finally , I dedicat e thi s thesi s to m y parents , [Minlon g Lu | an d Lichu n Wang , m y parent s in-law , Jitan g Fa n an d Fenghu a Shen , my wife , Shise n Fa n an d m y lovel y daughter , Zixi n Lu , wh o have alway s bee n there to suppor t m e an d give m e strengt h an d motivatio n t

o accomplis h thi s work .

i v


## VES01702 3

# Disseminatio n

Thi s wor k ha s bee n presente

d i n severa

l conference

s an d meetings, an

d ha s writte n i n paper s tha thav e bee n published an

d ar e i n th e proces s o f bein g published , give n a

s follows . Publication s L u Y. , Glas s H . D. , Easso n J . W. , (2009) . A n investigatio n o f particl e behaviou r

i n gas-soli d horizonta l pip e flo w b y an extende dLD A Technique . Fuel . Accepte d(JFUE-D-08-00741) . L u Y. , Glas s D . H. , Easso n W . J. , (2008a) . Investigatin g particle s behavio r i n gas-soli dhorizonta l pip e flo w b y an extende dLase r Dopple r Anemometr y Technique . In : Proceeding s o f 7th Europea n Conferenc e o n Coa l Research an dit s Applications , September 2 n d- 5 t h , Cardiff , U K . L u Y- , Glas s D . H. , Easso n W . J. , Crappe r M. , (2008b) . Investigatio n o f th e Flo w Pattern s o f Gas-soli dgranula

r flo w i n ahorizonta l pip e b y FLUEN T & EDEM . In : Proceeding s o f Particl e System s Analysi s 2008 , September 1 s t - 3 r d , Stratford , UK . L u Y. , Glas s D . H. , Easso n W . J. , (2007) . Investigatin g Flo w Propertie s o f Coa l Biomas s Blend s i n Pneumati c Conveyin g Syste mb y Computationa l Flui dDynamics . In : Proceeding s o f 200 7 internationa l conferenc e o n Coa l Scienc e an dTechnology , Augus t 28*

- 31 t h , Nottingham , UK . 

### Presentation s L u Y. , Glas s D . II. , Easso n W . J. , (2008a) . Investigatin g particle s behavio r i n gas-soli dhorizonta l pip e flo w b y an extende dLase r Dopple r

Anemometr y Technique . 7t h Europea n Conferenc e o n Coa l Researc h an dits Applications , September 2 ai - 5 t h , Cardiff , UK . (Ora l presentation) . L u Y , Glas s D . H. , Easso n W . J. , Crappe r M. , (2008b) . Investigatio n o f the Flo w Pattern s o f Gas-soli dgranula

r flow i n ahorizonta l pip e b y FLUEN T & EDEM . In : Proceeding s o f Particl e System s Analysi s 2008 , September 1 s t - 3 r d , Stratford , UK . (Ora l presentation) . L u Y. , Glas s D.H. , Easso n W . J. , (2008c) . Visualizin g particl e characteristic s i n ahorizonta l pneumati c conveyin g system , In : 21s t Annua l Scottis h Flui dMechanic s Meeting , Ma y 22 n d , Edinburgh , UK . (Poster ) L u Y. , Glas s D . H. , Easso n W . J. , Crappe r M. , (2008d) . A compariso n o f th e Numerica l Result s Investigate db y EDE M & Fluen t an dthe Experimenta l Dat ai n aGas-soli dHorizonta l Pip e Flow . In : Proceeding s o f EDE M Use r

Grou p Meetin g 2008 , Apri l 28th - 30th , Edinburgh , U K . (Poster) L u Y. , Glas s D . H. , Easso n W . J. , (2007) . Investigatin g Flo w Propertie s o f Coa l Biomas s Blend s i n Pneumati c Conveyin g Syste mb y Computationa l Flui dDynamics . 200 7 internationa l conferenc e o n Coa l Scienc e an dTechnology , Augus t 28*

- 31 t h , Nottingham , UK . (Ora l presentation) .



### v


## VES01702 4

# Tabl e o f content s Abstrac ti Declaration ii i Acknowledgement

s iv Disseminatio

n v Tabl e o f content s v i Tabl e o f figure s i x Tabl e of table s xii i Nomenclatur

e xiv Chapte r 1 1 1.1 GLOBA L WARMIN G AN D CO-FHUN G TECHNIQUE S 1 1. 2 CO-FIRIN G ACTIVITIE S AN D TH E TECHNICA L PROBLEM S O F HANDLIN G TH E FUE L MIXTUR E 3 1. 3 PNEUMATI C CONVEYIN G FUNDAMENTAL S FO RCO-FIRIN G APPLICATION S 5 1. 4 OBJECTIVE S AN D CONTRIBUTION S I N THI S THESI S 7 

## Chapter 2 9 2. 1 LITERATUR E REVIE W O N PNEUMATI C CONVEYIN G I N CO FIRIN G APPLICATION S 9 2. 2 NUMERICA L MODE L AN D FLUI D CONDITION S 1 1 2.2.1 Discrete Phase Model for gas-solid

simulations 1 1 2.2.2 The k-e turbulence model 1 2 2.2.3 Numerical

convergence criteria 1 3 2.2.4 Model geometry and

mesh Grids 1 3 2.2.3 Flow Conditions and Selecting Numerical

Parameters 1 4 2. 3 RESULT S AN D DISCUSSIO N 1 6 2.3.1 Particle trajectories in the pipe 1 7 2.3.2 The effect

of airconveying velocity 2 0 2.3.3 The effect

of pipe roughness 2 1 2.3.4 The effect

of particle size 2 1 2.3.5 The characteristics of particle mean velocity in terms of particle Stokes Number2 2 2. 4 CONCLUSION S 2 5 

## Chapter 3 2 7 3. 1 INTRODUCTIO N 2 7 3.1.1 The briefprinciple of LDA 2 7

v i



## VES01702 5

### 3.1.2 Literature view of LDA applications in gas-solidflow 2 9 3.2. EXPERIMENTA L APPARATU S 3 9 3. 3 DEVELOPIN G TH E SPATIA L TRANSFOR M MATRI X FO RLD A PIP E FLO W MEASUREMEN T 4 0 3.3.1 Parameters of

the LDA system 4 0 3.3.2 Optic principle of a ray crossing a pipe wall 4 1 3.3.3 Optic paths of

different colourbeams through a pipe 4 5 3.3.4 Developing the coordinate transform matrix forLDA pipe flow measurement

4 6 3. 4 SAMPL E RAT E O F LD A FO RGAS-SOLI D FLO W MEASUREMEN T 5 0 3. 5 SUMMAR Y 5 2 

## Chapter 4 5 3 4. 1 INTRODUCTIO N 5 3 4. 2 MEASURIN G TH E CROSS-SECTIONA L CHARACTERISTIC S O F TH E AXIA L AI RVELOCIT Y (U M 

### ) I N A HORIZONTA L PIP E 5 4 4. 3 AI RVELOCIT Y I N TH E RI G VERTICA L PIP E AFTE RA 90 ° BEN D 5 7 4. 3 CONCLUSION S 6 6 

## Chapter 5 6 8 5. 1 FLUI D CONDITION S AN D MEASUREMEN T PARAMETER S 6 8 5. 2 DETERMININ G TH E PROPE RSAMPL E RAT E O F LD A 7 0 5. 3 EXPERIMENTA L RESULT S O N PARTICL E DYNAMIC S I N A HORIZONTA L PIP E 7 2 5.3.1 Features of

the measured

parameters at

a typical point 7

3 5.3.2 Characterizing the experimental data on a pipe cross-section 7 4 5.3.3 The development

of cross-sectional

fluid patterns in a horizontal pipe 7 5 5.3.3.1 Glass beads less than 50/im (the first type) 7 9 5.3.3.2 Glass beads within the range 70 to 110 /um (the second type) 8

2 5.3.3.3 Glass beads within the size range 180~300fim (the third type) 8

5 5. 4 PARTICL E DYNAMI C BEHAVIOU RI N A VERTICA L PIP E DOWNSTREA M O F A 90 ° ELBO W 8 8 5.4.1 Glass beads less than 50ym (the first type) 8 9 5.4.2 Glass beads within the size range 70~110jum (the second type) 9

4 5.4.3 Glass beads within the size range 180~300(tm (the third type) 9

9 5. 5 DISCUSSIO N AN D COMPARISO N 10 4 5.5.1 The discrepancy between airvelocity and particle velocity in the horizontal

pipe 10 4 5.5.2 Particle dynamics in the vertical pipe downstream of

a right angle elbow 10 8 5.6 SUMMAR Y AN D CONCLUSION S 11 0

v i i

## Chapter 6 11 2 6. 1 INTRODUCTIO N 11 2 6. 2 EXPERIMENTA L SETU PAN D FLO W CONDITION S 11 6 6. 3 VIDE O & IMAG E PROCESSIN G SYSTE M 11 7 6.3.1 Principle of

decoding a MPEG-2 video 11 9 6.3.2 Strategy forprocessing large volume of uncompressed

frames (AVI files) 12 1 6.3.3 Particle diameter

and spatial position measurement

12

2 6. 4 RESULT S & DISCUSSIO N 12 8 6. 5 SUMMAR Y AN D CONCLUSION S 13 3 

## Chapter 7 13 5 7. 1 INTRODUCTIO N 13 5 7. 2 NUMERICA L MODEL S AN D THEI RPARAMETER S 13 7 7.2.1 Mathematical

models 13 7 7.2.2 Experimental

rig and numerical

geometry 14 0 7.2.3 Fluid

conditions at

inlet 14 0 7.2.4 Experimental

cross-sectional

flow patterns of

solid phase 14

2 7. 3 RESULT S AN D COMPARISON S 14 3 7.3.1 Flow patterns of

solid phase investigated

byDPM 14

3 7.3.2 Flow patterns of solid phase investigated

by Discrete Element Method 14 6 7. 4 DISCUSSIO N 14 7 7.5 CONCLUSION S 14 9 

## Chapte r 8 15 1 8. 1 SUMMAR Y O F RESULT S 15 1 8. 2 RECOMMENDATION S FO RFUTUR E WOR K15 6 8. 3 PUBLICATION S ARISIN G FRO M TH E PROJEC T 15 7 

## Reference

s 15 8

vii i



## VES017027

# Tabl e o f figure s
Figur e 1 Th e sketc h o f CO 2 cycl e i n co-firin g application s 2 Figur e 2. 1 Experimenta l ri g (a ) an dth e mes h grid s o f th e numerica l mode l (b , c ) 1 4 Figur e 2. 2 Geldart' s classificatio n o f fluidizatio n behaviou r fo r fluidizatio n 1 5 Figur e 2. 3 Th e convergenc e behaviou r o f numerica l simulations , (a ) th e evolutio n o f stream wis e ai r velocit y profil e acros s th e pip e a t x-2.5 m(b ) th e developmen t ofth e relativ e erro r

o f th e velocit y t o it s averag e valu e versu s numerica l iteratio n o n nin e referenc e point s 1 7 Figur e 2. 4 Particle s trajectorie s (runnin g directio n fro mrigh t t o left ) 1 8 Figur e 2. 5 Trajectorie s an dth e variation s o f (U p x , U p y ) fo r

tw o selecte dparticle s 1 9 Figur e 2. 6 Particl e trajectorie s wit h differen t conveyin g velocitie s 2 0 Figur e 2. 7 Particle s trajectorie s wit h differen t pip e roughnes s height s 2 1 Figur e 2. 8 Trajectorie s wit h differen t particl e size s 2 1 Figur e 2. 9 Th e evolutio n o f th e mea n particulat e velocitie s U p xan dU p yfo r pulverise dcoal2 3 Figur e 2.1 0 Evolutio n ofth e mea n particulat e velocitie s U p xan dU p yfo r woo dparticles... . 2 4 Figur e 3. 1 Th e schemati c diagra mo f alaser-Dopple r

anemometr y (DANTEC , 2008 ) 2 8 Figur e 3. 2 Sketc h ofth e experimenta l rig.. . 3 9 Figur e 3. 3 Th e geometri c sketc h o f abea mrefractio n o n acurv e 4 1 Figur e 3. 4 Th e geometri c sketc h o f abea mtranslatin g adistanc e L 4 2 Figur e 3. 5 Th e schemati c o f ara y crossin g apip e 4 3 Figur e 3. 6 Flo w chart

o f determinin g th e optica l pat h o f ara y crossin g apip e wal l 4 4 Figur e 3. 7 Crossin g poin t o f blu e beam s shiftin g toward s th e pip e cente r lin e (Units : mm)4 6 Figur e 3. 8 Cros s poin t o f gree n beam s movin g t o th e pip e cente r lin e (Units : mm ) 4 6 Figur e 3. 9 Th e experimenta l coordinat e (Oxzy) , th e prob e coordinat e (O'x'yV ) an dth e

initia l arrangemen t

o f th e prob e 4 7 Figur e 3.1 0 Variation s ofth e crossin g poin t o f blu e beam s agains t

prob e angl e 4 8 Figur e 3.1 1 Variation s ofth e crossin g poin t o f gree n beam s agains t

prob e angl e 4 9 Figur e 3.1 2 I n th e horizonta l pip e a t th e -5 ° prob e angl e 5 0 Figur e 3.1 3 I n th e vertica l pip e a t th e -5 ° prob e angl e 5 0 Figur e 3.1 4 Th e sketc h o f particl e signal s recorde db y LD A 5 1 Figur e 4. 1 2 D schemati c diagra mo f tw o selecte dcros s section s i n th e rig horizonta l pipe. . 5 4 Figur e 4. 2 Velocit y profile s o f th e axia l ai r

velocit y (U x ) a

t x=-200 , -30 0 m malon g 5 6 Figur e 4. 3 Cross-sectiona l distributio n ofth e axia l ai r velocit y distributio n (U x ) a t tw o horizonta l cross-section s o f x=-20 0 an d-300m mfro mth e ben dinle t respectively , under ai r conveyin g velocit y 12m/s ) 5 7 Figur e 4. 4 2 D schemati c diagra mo f cros s section s alon g th e vertica l pip e behin da90 ° ben d (R/D=1.3 , Ri s th e ben dradiu s 100m man dD i s pip e diamete r 75mm ; 0 D i s 15m mawa y fromth e ben doutlet ) 5 7 Figur e 4. 5 Experimenta l cross-sectiona l distribution s o f th e axia l ai r

velocit y (U a y , m/s ) alon g th e vertica l pip e behin da90 ° ben d(R/D= l .3 , Ri s th e ben dradiu s 100m m an dD i s pip e diamete r 75mm ; 0 D i s 15m mawa y fro mth e ben doutlet ) 5 9



### i x



## VES01702 8Figur e 4. 6 Numerica l cross-sectiona l distribution s ofth e axia l ai r velocit y (U a y , m/s ) alon g th e vertica l pip e behin da90 ° ben d(R/D= l .3 , Ri s th e ben dradiu s 100m man dD i s pip e diamete r

75mm ; O D i s 15m mawa y fromth e ben doutlet ) 6 0 Figur e 4. 7 Experimenta l cross-sectiona l distribution s o f th e horizonta l ai r

velocit y (Uax , m/s ) alon g the vertica l pip e alon g th e vertica l pip e behin da90 ° ben d(R/D=1.3 , Ri s th e ben dradiu s 100m man dD i s pip e diamete r 75mm ; 0 D i s 10m mawa y fro m th e ben doutlet ) 6 1 Figur e 4. 8 Numerica l cross-sectiona l distribution s ofth e horizonta l ai r velocit y (Uax ) alon g th e vertica l pip e behin da90 ° ben d(R/D=1.3 , Ri s th e ben dradiu s 100m man dD i s pip e diamete r

75mm ; 0 D i s 10m mawa y fromth e ben doutlet ) 6 3 Figur e 4. 9 Profile s o f

Ua x an dU a yalon g th e x axi s a t fou r selecte dvertica l cross-sections . 6 4 Figur e 4.1 0 Profile s o f Ua x an dU a yalon g th e z axi s a t fou r selecte dvertica l cross-section s 6 6 Figur e 5. 1 Particl e distributio n fo r th e secon dtyp e o f

glas s bead s 6 9 Figur e 5. 2 Particl e numbe r rat e agains t

th e sampl e rat e o f

LD A o n th e sectio n 300m mawa y fro mth e elbo w inle t

ai r velocit y 12m/s , soli dloadin g rati o abou t 1.6 % 7 1 Figur e 5. 3 Th e measure dparticl e velocit y a t asampl e poin t

i n thre e axe s 7 3 Figur e 5. 4 Cross-sectiona l flo w pattern s describe db y th e distribution s o f particl e mea n velocit y an dparticl e numbe r rate respectivel y (U a =12m/s ; particle s withi n th e siz e rang e 70~ 1 lOum ) 7 4 Figur e 5. 5 Th e sketc h o f eigh t measuremen t

cross-section s alon g th e horizonta l pip e 7 6 Figur e 5. 6 Cross-sectiona l distribution s ofth e mea n value s o f {U p x } an dth e granula r temperatur e {© } a s wel l a s particl e numbe r {N } a t an ai r conveyin g velocit y I2m/ s 7 8 Figur e 5. 7 Developmen t o f cross-sectiona l distribution s o f th e dimensionles s axia l particl e velocit y {U p x / U a } ofth e firs t typ e o f glas s bead s (<50um ) unde r a n ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 0.19 % 8 0 Figur e 5. 8 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s particl e numbe r rat e {ln(N /

2(N)) } ofth e firs t

typ e o f glas s bead s (<50um ) unde r a n ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 0.19 % 8 1 Figur e 5. 9 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s axia l particl e velocit y {U p x / U a } ofth e secon dtyp e o f glas s bead s (70~ 1 lOum ) unde r an ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 1.9 % 8 3 Figur e 5.1 0 Developmen t o f cross-sectiona l distribution s o f th e dimensionles s particl e number rat e {ln(N /

S(N)) } ofth e secon dtyp e o f glas s bead s (70~ 1 lOum ) unde r a n ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 1.9 % 8 4 Figur e 5.1 1 Developmen t o f cross-sectiona l distribution s o f th e dimensionles s axia l particl e velocit y {U p x / U a } o f

th e thir dtyp e o f

glas s bead s (180~300um ) unde r an ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 1.9 % 8 6 Figur e 5.1 2 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s particl e number rat e {ln(N /

S(N)) } o f

th e thir dtyp e o f

glas s bead s (180~300um ) unde r an ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 1.9 % 8 7 Figur e 5.1 3 Th e arrangemen t o f measuremen t

cross-section s i n th e vertica l pip e 8 9 Figur e 5.1 4 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s axia l particl e velocit y {U p y / U a } ofth e firs t typ e o f glas s bead s (<50um ) under a n ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 0.19 % i n th e vertica l pip e behin da n elbo w (R/D=1.3 ) 9 1 Figur e 5.1 5 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s horizonta l particl e velocit y {U p x /max(abs(U p x )) } ofth e firs t typ e o f glas s bead s (<50fim ) unde r a n ai r conveyin g velocit y U a =10m/ s an dth e soli dmas s loadin g rati o 1.9 % i n th e vertica l pip e behin dan elbo w (R/D=1.3 ) 9 2 Figur e 5.1 6 Developmen t o f cross-sectiona l distribution s o f th e dimensionles s particl e



### x


## VES01702 9

### 9 3 Figur e 5.1 7 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s axia l particl e velocit y {U p y 

### / U a 

### } o f

th e secon dtyp e o f

glas s bead s (70~110(xm ) unde r an ai r conveyin g velocit y U a 

### =10m/ s an dth e soli dmas s loadin g rati o 0.19 % i n th e vertica l pip e behin da n elbo w (R/D=1.3 ) 9 6 Figur e 5.1 8 Developmen t o f cross-sectiona l distribution s o f th e dimensionles s horizonta l particl e velocit y {U p x 

### /rnax(abs(U p x 

### )) } ofth e secon dtyp e o f glas s bead s (70- 1 lOum ) unde r

an ai r conveyin g velocit y U a 

### =10m/ s an dth e soli dmas s loadin g rati o 1.9 % i n th e vertica l pip e behin da n elbo w (R/D= l .3 ) 9 7 Figur e 5.1 9 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s particl e numbe r rate {N /E (N) } o f

th e secon dtyp e o f

glas s bead s (70- 1 lOum ) unde r a n ai r conveyin g velocit y U„=10m/ s an dth e soli dmas s loadin g rati o 1.9 % i n th e vertica l pip e behin da n elbo w (R/D=1.3 ) 9 8 Figur e 5.2 0 Developmen t o f cross-sectiona l distribution s o f th e dimensionles s axia l particl e velocit y {U p y 

### / U a 

### } ofth e thir dtyp e o f glas s bead s (180~300um ) unde r a n ai r conveyin g velocit y U a 

### =10m/ s an dth e soli dmas s loadin g rati o 0.19 % i n th e vertica l pip e behin da n elbo w (R/D= l .3 ) 10 0 Figur e 5.2 1 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s horizonta l particl e velocit y {U p x 

### /max(abs(U p x 

### )) } ofth e thir dtyp e o f glas s bead s (180~300um ) under

a n ai r conveyin g velocit y U a 

### =10m/ s an dth e soli dmas s loadin g rati o 1.9 % i n th e vertica l pip e behin da n elbo w (R/D=1.3 ) 10 1 Figur e 5.2 2 Developmen t o f cross-sectiona l distribution s ofth e dimensionles s particl e numbe r rat e {N/£(N) } ofth e thir dtyp e o f glas s bead s (180-300um ) unde r a n ai r conveyin g velocit y U a 

### =10m/ s an dth e soli dmas s loadin g rati o 1.9 % i n th e vertica l pip e behin da n elbo w (R/D=1.3 ) 10 3 Figur e 5.2 3 Th e vertica l profil e o f axia l mea n velocit y fo r fou r type s o f particle s a

t th e sectio n I D i n th e horizonta l pip e (U a 

### =10m/s , ai r conve y velocity ; First : glas s bead s les s tha n 50[im ; Second : glas s bead s withi n 70-11 0 um ; Third : glas s bead s withi n 180-30 0 am ) 104 Figur e 5.2 4 Experimenta l dat ao f Hube r an dSommerfel d(1994 ) fo r flo w i n ahorizonta l pip e b y Phase Dopple r

Anemometr y under

ai r conveyin g velocit y 23m/ s fo r glas s bead s wit h amea n siz e 40u m10 5 Figur e 5.2 5 Th e experimenta l dat aobtaine db y Kussi n an dSommerfel d(2002 ) 10 6 Figur e 5.2 6 Tsuji' s experimenta l dat a(1982 ) b y LD A i n ahorizonta l pip e 10 6 Figur e 5.2 7 Experimenta l dat ao f Yilma z an dLev y (2001 ) b y usin g Optical-Fibr e velocimetr y 10 7 Figur e 5.2 8 Profile s o f

th e axia l particl e velocit y {U p y 

### } an dparticl e numbe r rat e {N } alon g th e x axi s o n th e sectio n 0 D i n th e vertica l pip e downstrea mo f th e righ t angle d elbow . (U a 

### =10m/s , ai r

conve y velocity ; First : glas s bead s o f siz e les s tha n 50um ; Second : glas s bead s withi n th e siz e rang e 70-11 0 um ; Third : glas s bead s withi n th e siz e rang e 180-30 0 um ; R : pip e radiu s 37.5mm ) 10 8 Figur e 5.2 9 Profile s ofth e axia l particl e velocit y an dparticl e mas s concentratio n (Hube r an d Sommerfeld , 1994 ) 10 9 Figur e 5.3 0 Profil e o f

th e axia l particl e velocit y an dparticl e concentratio n a t th e positio n o f z/D= l under

differen t

flui dcondition s (Yilma z andLevy , 2001 ) 11 0 Figur e 6. 1 Sketche s o f

experimenta l ri g an doptica l arrangemen t fo r experiment s 11 6 Figur e 6. 2 Flo w chart

o f vide o an dimag e processin g 11 8 Figur e 6. 3 Thre e type s o f picture s i n avide o strea m(re dcolo r arro w mean s bidirectional ) 11 9

x iFigur e 6. 4 Fou r specifi c frame s i n an AV I vide o 12 1 Figur e 6. 5 Th e regio n o f th e pip e cross-sectio n o n afram e 12 3 Figur e 6. 6 Particl e image s o n th e pip e cross-sectio n 12 4 Figur e 6. 7 Denoisin g th e imag e (a ) an dseparatin g th e backgroun d(b ) 12 5 Figur e 6. 8 Th e imag e wit h it s backgroun dsubtracte d(a ) an dit s binar y imag e (b ) 12 6 Figur e 6. 9 Particl e sampl e chai n code s wit h 8-wa y connectivit y templat e 12 7 Figur e 6.1 0 Particl e diamete r frequencie s b y numbe r an db y mas s o n fou r

exampl e frame s

12 9 Figur e 6.1 1 Th e variation s o f particl e numbe r

mea n siz e an dparticl e mas s mea n siz e ove r I s : 13 0 Figur e 6.1 2 Cross-sectiona l distribution s o f th e dimensionles s particl e countin g numbe r an d th e dimensionles s particl e concentratio n ( N i s th e particl e countin g number ; Ri s th e pip e radius ; {C p } i s th e loca l concentratio n o f soli dphase ) 13 2 Figur e 6.1 3 Th e contou r o f {ln(N/Z(N) } o n th e sectio n 3 D measure db y LD A (selecte dfro m Figur e 5.12 ) 13 2 Figur e 7. 1 Experimenta l ri g an dschemati c diagra mo f numerica l geometr y 14 0 Figur e 7. 2 Ai r

velocit y (U x , U yan dU z ) a t inle t 14 1 Figur e 7. 3 Cros s sectiona l distribution s o f Particl e velocit y an dparticl e numbe r rat e a t inle t ove r I s 14 1 Figur e 7. 4 Th e contour s o f particl e velocit y Up x an dparticl e coun t ove r I s a t th e sectio n x=455m m14 2 Figur e 7. 5 Th e contour s o f particl e velocit y U p xan dparticl e coun t ove r I s a t th e sectio n x=1000m m14 2 Figur e 7. 6 Contour s ofth e dimensionles s particl e instantaneou s velocitie s {U p x / U a } an dits

time-average dvalu e {<U p x /U a > } ove r 1000m s o n th e sectio n x=455rru n obtaine dfromsimulatio n usin g FLUEN T DP M (Ua=12m/s ) 14 4 Figur e 7. 7 Contour s ofth e time-average daxia l particl e velocit y {<U px > } an dparticl e

numbe r {N } ove r

I s o n tw o sampl e section s (x=455mm , 1000mm ) obtaine d fro mFLUEN T DP M 14 5 Figur e 7. 8 Th e flo w pattern s o f particl e mea n velocit y an dparticl e numbe r o n tw o sampl e section s (x=455mm , 1000mm ) obtaine db y usin g FLUEN T & EDE M 14 6 Figur e 7. 9 Compariso n ofth e numerica l an dexperimenta l vertica l profile s o f {<Upx>/Ua } a

t fou r differen t

position s alon g th e fluidflo w directio n (th e continuou s blu e lin e i s th e profil e a

t inlet ) 14 7 Figur e 7.1 0 Compariso n ofth e numerica l an dexperimenta l vertica l profile s o f particl e numbe r ove r I s at fou r differen t

position s alon g th e flui dflo w directio n 14 8



### xi i

# Tabl e of table s

Tabl e 2. 1 DP M mode l setu p 1 2 Tabl e 2. 2 Numerica l parameter s 1 6 Tabl e 2. 3 Particle s Stoke s numbe r an dtermina l velocit y 2 2 Tabl e 2. 4 Particl e mea n velocit y i n th e full y develope dregio n 2 5 Tabl e 3. 1 Th e application s o f a n individua l LD A (Singl e phas e measurement ) 3 2 Tabl e 3. 2 Th e application s o f LD A combine dwit h othe r instrument s fo r

gas-soli dflo w measurement s 3 3 Tabl e 3. 3 Developmen t o f LD A multifunctio n fo r gas-soli dflo w measuremen t 3 4 Tabl e 3. 4 LD A parameter s 4 1 Tabl e 5. 1 Comparison s ofth e axia l velocit y distribution s i n avertica l pip e downstrea mo f a ben damon g thre e type s o f glas s bead s an dai r

flo w 10 4 Tabl e 7. 1 Numerica l parameter s fo r DP M simulation s 13 9 Tabl e 7. 2 Numerica l parameter s fo r DEM-Fluen t

calculation s 13 9



### xii i



## VES01703 2

# Nomenclatur e (a , b , c ) Th

e directio n vecto r o f a bea m C pParticl

e concentratio

n (C m u , C i , C 2 ) k-

e mode l constant s CF D Computationa

l Flui d Dynamic

s d , d p Particl

e diamete r d f Distanc

e betwee n th e interferenc

e fringe s D Pip

e diamete r D p Particl

e diamete r DE M Discret

e Elemen tMetho d DP M Discret

e Phas e Mode l ECT Electrica

l Capacitanc

e Tomograph

y F s Saffma

n forc e F rFrau

d numbe r g Gravitationa

l constant , 9.8 1 m/s

2 I Chrominanc

e k Turbulen

tkineti c energ y KTh

e constan ti n th e Saffma n forc e equation

, 6.4 6

• Lengt h o f horizonta l pip e L • Lengt

h o f a particl e trajector y • Th e runnin g distanc e o f a bea m LD A Lase

r Dopple r Anemometr

y (nj , n

r ) Mediu

m refractive inde

x o n inciden to r refracte d sid e M TOptica

l translatio

n matri x MR ) Opti

c transfor m matri x a ta pip e oute r surfac e MR

2Optica

l transfor m matri x a ta pip e inne r surfac e N Tota

l numbe r o f particle s PD A Phas

e Dopple r Anemometr

y Q Quadrati

c chrominanc

e rTh

e distanc e betwee n a feedin

g positio n a tth e inle tan d pip e centerlin e
• Pip e radiu s R• Len

s radiu s • Curv e radiu s (R , G , B ) (Red

, Green , Blue ) R e Reynold

s numbe r g • Optica

l syste m matri x
• Are a o f a particl e trajector y S tStoke

s numbe r tTrave

l tim e crossin g a strip e o f th e interferenc

e fringe s



### xi vTh e minimu m tempora

l interva l betwee n tw o adjacen tparticle s t k Tim

e interva l betwee n tw o adjacen tparticle s T Measuremen

tinterva l u Flui

d loca l tim e average d velocit y Th e maximu m valu e o f u {"pk } Particl

e velocit y sampl e spac e u „ Th

e mea n particl e velocit y U Flui

d velocit y U o Ai

rconveyin

g velocit y u „ Ai

rconveyin

g velocit y U p Particl

e velocit y <U'p

2 >" 2 Granula

rtemperatur

e Up, Particl

e horizonta

l velocit y Up y Particl

e vertica l velocit y u , Particl

e termina l velocit y UD F Use

r Define d Functio n V i Uni

tvecto r o f a n inciden tbea m v , Uni

tvecto r o f th e refracte d bea m v . Th

e uni tvecto r o f th e nonna l ra y a ta poin t (xc > yo , z 0 ) Referenc

e poin to f a bea m (x.y.z ) A poin

tcoordinat

e o n a lin e
• Beam' s heigh to n inciden to r refracte d sid e • Beam' s initia l heigh t y o Beam'

s translatio

n heigh t 

### y, Beam'

s heigh tafte r refraction Y Luminanc

e

a 0Angl

e o f a n outboun d bea m ot tCrossing-angl

e betwee n refracted bea

m an d it s normal . • Th e crossing-angl

e betwee n inciden tbea m an d it s norma l vecto r • Angl e o f a n inboun d bea m s Rat

e o f dissipatio n o f turbulen tenerg y S Pip

e roughnes

s paramete

r g • Feedin

g angl e • Th e crossin g angl e o f tw o beam s @ Granula

rtemperatur

e
r » • Ai

rdynami c viscosit y • Mea n valu e o f th e intensitie

s o f a grou p pixel s c Varianc

e o f Root-mean-squar

e ofth e intensitie

s o f a grou p pixel s v Ai

rkinemati c viscosit y p Flui

d densit y

X

V



## VES01703 4Particl e densit y Pip e roughnes

s heigh t Bea m wavelengt

h



### xv i



## VES01703 5

# Chapte r 1 Introductio n

Coal is predicted

to remain the dominant energy source in world electricity generation in the near future. Co-firing in powerstations is a promising technique to generate enough electricity forthe energy demand

of a developing economy while simultaneously mitigating the risk of Global Warming by reducing CO2 ernissions. This chapteris intended briefly to introduce co-firing activities and the current key problems of

transporting the blend

of granularbiomass and

pulverised

coal in co-firing applications. Then some terms used in pneumatic conveying research are discussed so as to provide a uniform approach to the work referenced in subsequent

chapters. The objectives and the main contributions of

this research are summarized.

1. 1 GLOBA L WARMIN G AN D CO-FIRIN G TECHNIQUE S Unprecedente dcatastrophi c climati c anomalies , suc h a s blazin g ho t summers , bruta l winters , hurricanes , typhoon s an dcyclone s hav e occurre dfrequentl y i n recent years . Thes e natura l disaster s hav e been warnin g an dforcin g every natio n urgentl y to tackl e th e seriou s problem s produce db y globa l warming , whic h ha s bee n confirme db y overwhelmin g scientifi c evidence . Thi s show s tha

t the earth' s temperature ha s increase db y 0.4° C ove r the pas t century du e t o the greenhous e effec t

cause db y man-mad e fossi l combustio n (Baxter , 2005) . Si x gases , namel y carbo n dioxide , methane , nitrou s oxide , hydrofluorocarbon s (HFCs) , per-fluorocarbon s (PFCs ) an dsulphu r

hexafluoride , ar

e considere das greenhous e gase s whic h ca n tra p the hea

t fromth e su n o r th e hea t reflecte db y the eart

h i n th e atmosphere an dmak e the eart h muc h wanner . Thus , mor e than 160 nation s ratifie dth e 199 7 Kyot o Protoco l an dcommitte dto make legall y bindin g reduction s i n thei r

greenhous e ga s emission s (Matsuo , 1998) . A ne w globa l agreemen t t o fight globa l warmin g i n the pos t Kyot o Protoco l er ai s expecte dto b e conclude di n 200 9 a t the U N Climat e Chang e Conferenc e i n Copenhage n (Harris , 2008) . I n 2007 , th

e energ y targe

t o f the Europea n Unio n wa s set t o achiev e 20 % renewabl e energ y b y 202 0 an dthe UK' s shar e wa s suppose dt o b e 15 % o f th e UK' s energ y fro mrenewable s (BERR , 2008) . T o reac h thi s aim , thre e lega l measures , th e Climat e Chang e Lev y i n 2001 , the Renewable s Obligatio n (RO ) i n 200 2 an dthe Europea n Emission s Tradin g Schem e (E U ETS ) i n 2005 , hav e been enacte dto mov e th e UK' s econom y from ahigh-carbo n mode l t o alow-carbo nA n investigatio n o l particl e dynamic s i n a dilut e phase pneumati c conveyin g system
o r carbon-neutral on

e throug h providin g financia l benefit s fo r usin g renewabl e source s suc h as sola r power , win dpower , hydro-electri c power , geothermal energy , tida l power , wav e energ y an d biofuels . A s aresult , th e leve l o f

RO-eligibl e renewabl e generatio n i n U K has bee n increase d fro mles s tha

n 2 % i n 200 1 t o aroun d4.4 % i n 2006 . Especiall y fo r power plants , the license d electricit y supplier s wil l be require dt o increas e annuall y the fractio n o f renewabl e source s i n (hei r supplie delectricit y t

o 10 % b y 201 0 (AEA , 2006) . Amon g th

e eligibl e renewabl e sources , utilizatio n o f biomas s as a

n alternativ e energ y sourc e insteado f

fossi l fue l ha

s been advocate dan di s unde r intens e study acros s th e world . On e lin e o f enquir y focuse s o n explorin g the techniqu e o f generatin g electricit y b y usin g afue l blen do f pulverise dcoal an dbiomas s i n powe r stations . Thi s combustio n o f fossi l fue l mixe dwit h biomas s i s name dco-firin g o r co-combustion . I n general , co-firin g biomas s resource s ca n b e classifie dint o three categorie s (IPA , 2006) , suc h a s waste s (agricultura l productio n wastes , cro p residues , mil l woo dwaste s an durban wastes) , fores t product s (wood , loggin g residues , trees , shrubs , sawdus t

an dbark ) an denerg y crop s (shor t rotatio n wood y crops , herbaceou s wood y crops , grasses , starc h crops , suga r crops , oilsee dcrops) . Coa l powde r

Figur e 1 . Sketc h o f C0 2cycl

e i n co-firing application s In co-firin g applications , not onl y i s biomas s utilize da s asustainabl e alternativ e energ y sourc e whic h save s the usag e o f fossi l fuel , bu

t als o CO ? emissio n ca

n b e reduce dthroug h keepin g th e ne t amoun t o f CO 2 fro mthe biomas s neutral o r zero-emissio n i n th

e atmosphere . CO ? emissio n i n aco-firin g powe r

plan t i s show n i n Figur e 1 . Obviously , biomas s absorb s CO ? fro mthe atmospher

e i n it s growin g perio d(a) an drelease s oxyge n bac k throug h photosynthesi s (b ) a t th e sam e time . Whe n biomas s residual s ar e co-fire dwit h pulverise dcoa l i n powe r stations , th

e carbo n store di n themwil l combin e wit h oxyge n t o produc e carbo n dioxide , whic h i s emitte d

2


## VES01703 7Chapte r1 - Introductio

n bac k int o the atmospher

e a s a n exhaus t

gas . Durin g th e cycl e o f (a ) t o (c) , the tota l amount o f CO 2 i n th

e atmospher

e ca n b e kep t

constan t

throug h continue dplantin g an dgrowth o f the biomass . Accordin g t o the dat ao f Worl dEnerg y Outloo k {TEA , 2006) , fossi l fue l provide s ove r thre e quarter s o f

th e UK' s electricit y generatio n nowaday s an di s predicate dt o remai n th e dominan t energ y sourc e utilize dfo r powe r generatio n unti l 2030 . Th e globa l emissio n o f CO 2 i s estimate d t o b e 4 0 gigatonne s (Gt ) i n 2030 , whic h i s 1 4 G t mor e tha

n the 200 4 level . A hal f o f the C0 2 emissio n incremen t

wil l b e produce db y powe r generatio n ove r

th e projectio n period . O n the other hand , energ y deman di s substantiall y increasin g under the pressure o f

rapi durbanizatio n an dpopulatio n explosion . A s aresult , sustainabl e energ y polic y mus t both tackl e globa l warmin g an densur

e securit y o f

th e energ y supply . Developin g co-firin g technique s follo w thi s policy , sinc e i t i s apromisin g clea n wa y o f utilizin g abundant

coa l resource s t o provid e alow-carbo n energ y suppl y fo r

economi c development .

1. 2 CO-FIRIN G ACTIVITIE S AN D TH E TECHNICA L PROBLEM S O F HANDLIN G TH E FUE L MIXTUR E Basically , biomas s co-firin g can b e categorize das direc t co-firing , indirec t

co-firin g o r

paralle l co-firin g (DTI , 2006) . Direc t co-firing , whic h mean s burnin g coa l wit h biofuel s i n the sam e boile r usin g existin g o r

separat e mill s an dtransportatio n systems , i s mos t commonl y an dwidel y applie dt o handl e biomass . Conversely , indirec t co-firin g implie s tha

t an on-sit e gasificatio n o r pyrolysi s uni t

ca n b e use dt o conver t biomas s material s int o aclea n fue l gas , whic h ca n b e fired alon e or combuste dwit h coa l o r natura l gas . I n paralle l co-firing , fossi l fue l an dbiomas s ar e combuste dseparatel y an dthe steamproduce db y burnin g biomas s i s fe dt o acoal-fire dpowe r statio n where i t

i s upgrade dt

o th e highe r

temperature an dhighe r pressure condition s o f the larg e coa l plant . I n th e UK , biomas s facilitie s hav e been develope dfromtw o plant s i n 200 2 t o sixtee n unit s an d the volum e o f

electricit y produce db y co-fire dbiomas s has increase dsignificantl y t o an estimate d 2.5TW h ove r

2005/06 . S o far , mos t

type s o f boilers , suc h a s cyclon e boilers , grat e boilers , wall

firedo r tangentiall y firedpulverized-fue l (PF ) boiler s an dcirculatin g fluidize dbe d(CFB ) boilers , hav e been converte dt o co-firin g biomas s wit h coal . Thes e practica l experience s hav e confirme d tha t burnin g biomas s wit h fossi l fuel s ha s apositiv e impac t bot h o n th e environmen t an dthe economic s o f

powe r generatio n (DTI , 2007) ,

3



## VES01703 8A n investigatio

n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m Sam i e t al . (2006 ) summarize dpreviou s co-firin g studie s i n fou r conclusions : (1 ) Co-firin g can b e performe da t moderate an dhig h percentage s i n cyclon e boilers ; (2 ) Co-firin g can b e performe da t lo w percentage s i n P C boilers . Th e co-firin g rati o depend s o n th e pulverize r

performanc e whic h i n turn depend s o n the typ e o f biomas s fue l used . Mos t biomas s fuel s hav e afibrou s structur e (e.g . wood , switchgrass ) an dar e difficul t

t o grin dt o the sam e size s a s coa l use di n coa l pulverizers . Grindin g cost s determin e th e extent t o whic h biomas s ca n b e economicall y pulverized ; (3 ) Co-firin g i n P C boiler s may requir e separat e fue l fee dline s dependin g upo n th e capacity o f existin g pulverizers , typ e an dconditio n o f biomas s fuel s an dth e typ e o f pulverizer s used ; (4 ) Th e potentia l fo r

successfu l applicatio n o f co-firin g i s site-specific . I t depend s upo n the characteristic s o f

the powe r

plan t bein g considered , the availabilit y an dpric e o f biofiiel s withi n 50-10 0 mile s o f

th e plan t an dth e economi c value o f environmenta l benefits . However , applyin g curren t co-firin g technolog y i s als o challenge db y some technica l problem s (Biagini , 2005 ; Baxter , 2005) . Th e firs t issu e i s relate dt

o combusto r

foulin g an dcorrosio n du e t o th e alkalin e nature o f

the biomas s ash . Deposit s o f as h reduc e the hea

t transfe r an dmay als o caus e severe corrosio n a t hig h temperatures . Secondly , additiona l studie s ar e neede dabou t

the feedin g mechanis mtransportin g th e fue l mixtur e t o contro l th e co-firin g stat e i n agive n furnace . Thi s issu e i s acombination o f economic s an dcombustio n characteristics . Mor e wor k i s require d t o b e don e i n thi s area . Third , practica l pulverize r performanc e need s t o b e examined . I n curren t

co-firin g applications , existin g fue l transportatio n system s ca n b e classifie das thre e type s (Sam i e

t al. , 2001 ; Irelan de t

al. , 2004) . Th e first

i s usin g separat

e fee dline s an dseparat e burner s fo r

dealin g wit h coa l an dbiomas s fuel s respectively . I t ha s th e advantag e o f better contro l ove r

fue l flow rates . Therma l outpu t simila r t o coal-onl y firing require s highe r biomas s fee drates . I t

als o increase s capita l an dmaintenanc e costs . Firin g lo w heatin g valu e biomas s independentl y o f

coa l als o ha s aris k

o f poo r combustio n efficiency . Th e secon di s usin g separat e fee dline s an dacommo n burner . Thi s metho dca n als o b e divide dint o dua l inlet s an dtripl e inlet s o n furnaces . I n dua l inlets , coa l i s injecte di n th e primar y ai r inle t an dbiomas s i s injecte di n the swirlin g secondar

y ai r inle t (o r vic e versa) . I n tripl e inlets , tw o primar y ai r inlet s ar e use dt o fee d coa l an don e swirlin g secondar y ai r inle t t o injec t biomass . Th e thir dmetho di s tha t premixe d coal/biomas s blend s ar

e transporte di n commo n fee dline s t o acommo n burner . Sinc e the fue l blen dshare s the sam

e pipelines , thi s metho dsave s muc h investmen t i n buildin g ane w fee d system , an di s therefor e economicall y advantageous . Sinc e dilut e pneumati c conveyin g system s are commonl y applie dt o transpor t pulverise dfue l i n

4



## VES01703 9Chapte r1 - Introductio

n
mos t coal-fire dpowe r

plants , ou r

researc h wil l focu s o n investigatin g the characteristic s o f transportin g biomass/coa l blend s i n acommo n dilut e pneumati c conveyin g system .

1. 3 PNEUMATI C CONVEYIN G FUNDAMENTAL S FO R CO-FIRIN G APPLICATION S Co-firin g biomas s wit h coa l i n th e sam e installatio n ha s bee n prove dt o b e an importan t renewable s technology , an di t ha s th e grea

t economi c advantag e o f re-usin g the existin g infrastructur e o f

powe r stations . Pneumati c conveying , whic h use s ai r t o conve y granula

r material s throug h apipeline , ha s bee n use dcommerciall y t o transpor t the pulverise dcoa l fo r man y year s i n coal-fire dpowe r stations . Th e curren t

existin g pneumati c conveyin g system s shoul db e retrofitte dt

o b e suitabl e fo r

transportin g the fue l blend . Thes e modification s includ e fue l handling , storag e an dfee dsystems . Sinc e biomas s granule s hav e significantl y differen t characteristic s frompulverise dcoa l (fo r instance , biomas s ha s les s heatin g value tha n tha t o f coals ) an dar

e als o mor e fibrous an dsofte r (biomas s density varie s from100 t o 50 0 kg/m 3 fo r fores t woo dan dcoa l density range s from1100 fo r low-ran k

coa l t o 233 0 kg/m 3 fo r hig h density pyrolyti c graphite) , thes e difference s i n propertie s mea n tha t there ar e potentia l problem s i n storage , bul k

handling , feeding , combustion , slagging , corrosio n an dgaseou s emissions . Accordin g t

o current

technica l report s o n co-firin g i n larg e utilit y boiler s (DTI , 2007) , the handlin g o f

the fue l mixtur e i s poo r becaus e o f

particl e siz e variation , hig h fibre an doversiz e particl e content . Additionally , biomas s particle s may b e adherent , corrosiv e an deve n abrasive . Moreover , downstreamparameter s i n furnaces , suc h a s combustio n efficiency , combustio n behaviou r

an das h product s o r

pollutants , ar

e als o relate dt

o th e condition s o f

feedin g th e fue l blend . I n vie w o f

thes e factors , i t

i s critica l t o investigat e ho w t o prepare an dhandl e th e fue l mixtur e t

o ensure th e optimu moperationa l perfonnanc e o f aco-firin g plant . Therefore , the proposa l fo r

2007-200 9 ke y topics- 2 o f TAS K 3 2 (Livingsto n e t

al. , 2007 ) outline dth e optimize d biomas s technolog y combination s throug h aworksho p o n fue l storage , handlin g an dpreparation , a s wel l a s system s analysis . Althoug h pneumati c conveyin g system s hav e bee n widel y applie dcommerciall y i n man y industria l fields an dther e ar e als o numerou s experimenta l an dnumerica l publishe dpaper s investigatin g phenomen alik e gravit y setting , roping , erosion , attrition , pressure-wav e propagatio n an dgas-soli dturbulenc e modulatio n i n pipes , understandin g o f fh e mechanis mo f pneumati c conveyin g i s stil l unde r development

du e t o it s complexity . Fo r example , i t

i s stil l difficul t t o measur e an dcontro l the mas s flo w rate o f asoli dphas e i n apip e an dt o distribut e gas 5



## VES01704 0A n investigatio

n o f particl e dynamic s i n a dilut e phas e pneumati

c conveyin

g syste m soli dflo w fro mamai n pip e t o severa l sub-pipe s a t a n equa l mas s rate o r

aspecifi c rati o (DTI , 2003) . I n researc h o n co-firin g applications , mos t previou s studie s focuse do n combustio n issue s suc h a s combustio n efficiency , pollutan t formation , carbo n conversion , as h management , corrosion , fue l chemistrie s associate dwit h blendin g an dother downstreamimpacts . Th e relevan t literatur e whic h focuse s o n transportin g the pulverize dbiomas s an dcoa l fue l suppl y i s particularl y sparse . Befor e introducin g thi s Ph D wor k i n detail , some easil y confuse ddefinition s i n pneumati c conveyin g researc h ar

e give n her

e fo r referenc e i n orde r

t o provid e aunifor mapproac h t o the wor k i n th e nex t

subsequent

chapters . Thes e term s ar e cite di n the tw o reference s (Mills , 2004 ; Sevill e e t al. , 1997) . Airsuperficial

velocity /superficial

fluid velocity. Thi s i s th e velocit y o f the ai r disregardin g th e presenc e o f

the soli dparticle s o r

porou s media . I n apipeline , i t i s th e ai r

velocit y base d upo n the empt

y cross-sectiona l are aan dneglectin g the spac e occupie db y th e conveye d material . Fo r

example , unde r

th e conditio n o f

fluidflow a

t volumetri c rate Q f

alon g apip e o f cross-sectiona l are aA , ai r superficia l velocit y i s define dt o b e U(=Qf/A . Airphase velocity. I t

i s th e same as ai r

superficia l velocity . "v - Air retention. Th e abilit y o f abul k materia l t

o retai n ai r

i n the interstitia l space s betwee n particle s fo r

aperio do f

time . -v - Airconveying velocity at pipeline inlet. Thi s i s th e superficia l ai r velocit y a

t th e poin t

where th e materia l i s fe dint o the pipeline . I n asingl e bor e pipelin e thi s wil l b e th e lowes t ai r velocit y i n the conveyin g lin e an ds o i t mus t b e greater

tha n th e minimu mconveyin g ai r velocit y require dt o ensure successfu l conveyin g o f the material . I n avacuu mconveyin g syste mi t i s approximatel y equa l t o the free ai r

velocity . Airconvevine velocity at pipeline exit. Thi s i s th e superficia l ai r velocit y a

t th e en do f

a conveyin g lin e wher e fh e materia l i s discharge dint o th e receivin g vessel . I n asingl e bore pipelin e thi s wil l b e th e highes t ai r velocit y i n th e conveyin g line . I n apositiv e pressure conveyin g syste mi t

i s approximatel y equa l t o th e free ai r

velocity . -v * Cross-sectional

flow patterns. Thes e ar e define das geometri c contour s o n apip e cross sectiona l characteristi c o f som e parameter s lik e particl e velocity , particl e numbe r rat e an d soli dphas e concentratio n i n apneumati c conveyin g system . A Delivered

volume concentration. Thi s i s define das the rati o o f soli dphas e volumetri c flow rat e t o th e mixtur e volumetri c flow rate , whic h i s expresse das C v< j=Q s /(Qf+Qs) , where Q s an dQ f ar e fh e soli dphas e volumetri c flow rate an dai r phas e volumetri c flo w rat e respectively .

6


## VES01704 1Chapte r1 - Introductio

n "Y - Flow reeimes. Thes e term s ar e use dt o describ e th e stat e o f gas-soli dflo w b y the evidenc e o f it s macroscopi c appearanc e alon g th e pip e axia l direction . Basically , thre e majo r flo w regimes : suspensio n flow (dilut e phase) , movin g be dtyp e flow (dens e phase ) an dslu g o r plu g typ e flow (dens e phase ) hav e bee n recognize dt o exis t i n pneumati c conveying . •s > Free aircondition. Thi s i s specifie das th e conditio n a t th e standar datmospheri c pressur e (p= l .013xl0 5 Pa ) an dth e standardatmospheri c temperature (t=15°C) . Free airvelocity. Thi s i s th e superficia l velocit y o f th e ai r whe n evaluate da

t free ai r condition . •v - Particle velocity /

particle actual

velocity. Thi s i s define da s th e velocit y o f aparticl e i n a pipe . Her e the soli dphas e i s considere das agrou p o f discret e particle s immerse di n the fluid. -0

- Slip velocity. Thi s i s defme das the absolut e differenc e betwee n ai r phas e velocit y an dsoli d phas e velocity . Slip ratio. Thi s i s define di n term s o f the soli dphas e velocit y divide db y ai r superficia l velocity . •y - Solid phase velocity /

superficial

particle velocity. Whe n soli dphas e i s als o considere das a continuou s fluidlik e ai r an dha s avolumetri c rat e Q s alon g apip e o f

cross-sectiona l are aA , the soli dphas e velocit y U si s the n define da s U S =Q S /A . •v - Solid velocity. Thi s i s the sam e a s soli dphas e velocity . -$* Void fraction/volume fraction /voidase. I t mean s th e volum e rati o occupie db y the fluid.

1. 4 OBJECTIVE S AN D CONTRIBUTION S I N THI S THESI S Transportin g pulverise dcoa l wit h biomas s i n apneumati c conveyin g syste mcan b e essentiall y considere da s aspecia l cas e o f multi-componen t

gas-soli dpip e flow , i n whic h th e soh dphas e consist s o f

tw o o r mor e particulat e material s suc h as coa l powde r an dsawdus t

Thes e particle s ar e distinguishe db y thei r densit y an dgeometri c characteristics . Th e objective s o f thi s thesi s ar

e t o evaluate the influenc e o f variou s factor s o n th e particl e behaviou r o f the differen t

material s i n a pip e an dt o investigat e loca l informatio n o n th e soli dphas e suc h a s cross-sectiona l velocit y distributio n an dparticl e number distributio n b y numerica l simulatio n an dexperiments . Th e result s wil l b e o f

fundamenta l us e i n th e desig n o f fue l blen dtranspor

t system . Thes e aim s were me t

throug h the followin g activities : -v - Comparin g th e similarit y o f th e pulverise dcoa l an dbiomas s particle s i n apneumati c conveyin g syste mb y Computational Fluid Dynamics (CFD ) an dthe Discret e Elemen t Metho d(DEM ) (Chapte r 2 ; Chapter

7) . "v * Usin g Laser

DopplerAnemometry (LDA ) t o investigat e th e loca l informatio n o n th e soli d

7



## VES01704 2A n investigatio

n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m phas e a t severa l pip e cross-section s alon g the flui ddirectio n (Chapter 3 ; Chapte r

4 an d Chapte r 5) . Usin g a high definition digital camcordert o visualiz e an dmeasur e th e cross-sectiona l characteristic s ofth e soli dphas e (Chapte r 6) . Comparing the experimenta l dat awit h th e numerica l result s t o study th e reason s fo r any discrepancie s (Chapte r

7) . Specifi c contribution s outline di n thi s wor k are : •v - Numerica l result s indicat e tha t ther e exist s acritica l air

conveying velocity, acritical particle size an dacritical

pipe relative roughness i n apneumati c conveyin g system . Stokes Number ca n b e use dt

o classif y the similarit y o f

the mean particl e velocit y o f differen t

material s i n axia l an dgravit y direction s (L u e t al. , 2007) . < • A n algorith mt o calculat e th e spatia l optica l transformation matrix ha s bee n develope dt o calibrat e the positio n o f the lase r

beams ' crossin g poin t i n acircula r

pip e fo r

LD A measurement s (L u e

t al. , 2008a ; L u e t

al. , 2009) . A video and

image processing system ha s bee n develope dt o visualiz e an dmeasur e the spatia l distributio n o f

particl e siz e an dconcentratio n ove r apip e cross-sectio n (L u e t al. , 2008c) . Experimenta l datashow s two cross-sectional flow patterns whic h ca n b e classifie das an annularstructure o f

particl e velocit y contou r an da stratified

feature describin g particl e numbe r rate contour s (L u e

t al. , 2008a ; L u e

t al. , 2009) . - Y - Compariso n o f

the numerica l result s an dth e experimenta l dat aindicat e tha t usin g fh e current Discret e Phas e Mode l (DPM ) ca n reasonabl y estimate th e cross-sectiona l flow pattern s withi n a certain distance fromthe inlet . Thi s length i s approximatel y equa l t o the produc t o f particl e mea

n velocit y an dits hal f

free-falling tim e i n pipe . I n addition , considerin g th e effec t o f particle-particle interactions wil l improv e the accurac y o f the particles ' spatia l distribution s i n the pip e predicte db y numerica l simulation s (L u e t al. , 2008b ; L u e

t al. , 2008d) .



## VES01704 3

# Chapte r 2 Classifyin g th e Characteristic s o f Pulverize d Coa l an d Granula r Biomas s i n a Dilute Horizonta l Pip e Flo w

b y Computationa l Flui d Dynamic s

Particle dynamic behaviourof the solid phase in a dilute horizontal pipe flow was investigated at the start of the project

by using the Discrete Phase Model (DPM) in Fluent

6.2.16. The numerical

results indicate that

the Saffman force plays an important role in suspending particles at the boundary and that three critical

parameters of

the air: critical

conveying velocity, the critical particle size and

the critical pipe roughness, exist

in pneumatic conveying systems. Moreover, the Stokes numbercan be used as a similarity criterion to classify the mean particle dimensionless velocity of the different materials in the

fully developed

region. Laternumerical work appears in Chapter7.
2. 1 LITERATUR E REVIE W O N PNEUMATI C CONVEYIN G I N CO-FIRIN G APPLICATION S I n Chapte r

1 , Co-firin g wa s introduce da s apromisin g techniqu e t o mitigat e the ris k

o f Globa l Warmin g b y reducin g CO 2 emission , becaus e biomas s co-fire dwit h coa l ca n no t onl y utiliz e th e advantage s o f

coa l suc h as abundant resource s an dhig h therma l valu e bu t als o ha s th e grea

t environmenta l benefi t

o f CO 2 emissio n neutralit y i n the biomas s lif e cycle . Biomas s particle s an d pulverize dcoa l ca n b e conveye dint o furnace s o f apowe r plan t throug h aseparat

e o r commo n pipeline . Usin g acommo n conveyin g syste mi s muc h the leas t expensiv e optio n sinc e n o separat e fee dline s an dburner s ar e require dan dexistin g installation s ca n b e use dwit h mino r adaptation s o r retrofittin g (Sam i M . e t al , 2001) . Bu t

th e solutio n o f

som e technica l issue s lik e storing , feedin g an dpulverizin g th e mixe dfuel s ma y stil l b e require dbefor e the widesprea dadoptio n o f co-firin g i n powe r

stations . Despit e numerou s pneumati c conveyo r system s havin g bee n buil t t o handl e enormou s amount s o f granula r material s i n many industria l fields , understandin g o f the underlyin g physica l proces s i s ver y limite dan dther

e stil l exis t

considerabl e concern s an dtechnica l problem s du e to the complexit y o f

gas-soli dflo w i n pneumati c conveyin g system s (DTI , 2003) . Th e mai n challenge s li e i n th e contro l an dmeasurement o f granular

pip e flo w on-line . Especially , thi s i s acurren t technica l proble m(DTI , 2007 ; Livingsto n e t al , 2007 ) wit h differen t coal s an deve n mor e s o wit h biomass, sinc e there exis t significan t

difference s i n density , size , geometri c shap e an dmoistur e betwee n granula

r biomas s an dpulverize dcoal . Al l thes e difference s hav e grea t influenc e o n the



## VES01704 4Chapte r2 - Classifyin

g th e characteristic

s o f granula r biomas s an d pulverise

d coa l b y CF D stat e o r propertie s o f

the mixtur e flow. Fo r

example , pulverize dcoa l i s normall y conveye dt o th e furnac e b y adistributio n pip e network , whic h i s designe dt o distribut e equall y o r spli t th e pulverize dfue l throug h bifurcation s o r trifurcations . Th e evennes s o f distributio n wil l affec t combustio n efficiency , pollutan t productio n an dflame stability . Th e majorit y o f pneumati c conveyin g system s hav e bee n designe dan dcalibrate dt o handl e aspecifi c typ e o f granula r material . Whe n thes e conveyin g system s ar e retrofitte dt o conve y biomas s o r fue l blends , th e defaul t o r designe dconveyin g parameter s lik e minimu mpick-u p velocity , distributio n rati o o f a splitte r an dsoli dloadin g rati o . shoul db e re-calibrate dan dvalidated . S o far , mos t

co-firin g researche s i n powe r generatio n hav e focuse do n combustion-relate d activitie s suc h as measurin g an dmodelin g th e combustio n flame, combustio n efficienc y an dNO x reduction , pollutan t

formation , as h management , the physica l propertie s o f coal-biomas s blend s an dothe r

issue s relate dt

o combustion . Onl y ahandfu l o f paper s hav e begu n t

o investigat e th e fundamental s o f

pneumati c transport

o f the fue l blend s o f

pulverize dcoa l an dgranula r biomass . Granad ae

t al . (2006 ) speciall y designe dahopper fo r steadil y injectin g pellet s o f thre e fores t residue s (Eucalyptus , pin e an dpin e bark) . Hi s experimenta l result s indicat e tha t pin e bar k i s th e mos t suitabl e produc t

fo r co-firin g a

s pellet s an dtha

t ascre w feede r

cause s highe r

level s o f segregatio n o f

fue l mixtures . Wal l shea r an ddirec t

shear experiment s were carrie dou t b y Zulfiqa r e t al . (2006 ) t o study shea r betwee n the mixtur e fuel s (typica l Australia n coa l an dwoo d chips ) an dth e shea

r betwee n fue l blend s an dthe wall . Th e biomas s wa s pin e sawdus t wit h equivalen t

diamete r 100 u mo r

woodchip s wit h averag e dimension s o f 2* 3 cm 2(widt h b y length) . Thei r experimenta l dat aindicat e that coal-woodchi p blend s wil l significantl y increas e th e ris k o f blockag e an dflow stoppage . Melande r e t al . (2004 ) use dth e Particl e Imag e Velocimetr y (PIV ) techniqu e t o measur

e the concentratio n an dvelocit y o f woo dfibres i n avertica l pneumati c conveyin g system . Thei r dat aconfirme dtha

t PI V i s ausefu l too l fo r measurin g th e propertie s o f th e dilut e fibre-gas flows. Th e measure dprofile s o f ai r velocit y sho w tha

t the y ar e strongl y affecte db y fh e volum e fractio n o f woo dfibres. Joppic h an dSalma n (1999 ) studie dthe steadines s o f ascrew feede r

use dt o fee dwoo dpowder . B y usin g avibrato r feede r mounte da

t the downstreamen do f

the scre w conveyor , the tota l feedin g performanc e i s significantl y improved . I n researc h int o dilut e particle-lade n pip e flow o f asingl e material , Hube r e t al . (1998 ) an d Sommerfel d(2005 ) summarize dseve n importan t phenomena : particl e transpor t du e t o turbulence , gravitationa l settling , wal l roughnes s effect , particle-wal l collisions , inter-particl e collision s an d inertia l behaviou r

i n pip e bends . Mill s (2004 ) publishe dapractica l boo k introducin g the principle s o f

desig n o f

apneumati c conveyin g system . I n researc h int o the pneumati c conveyin g mechanism , Fa n e

t al . (1998 ) addresse dthe basi c principle s an dfundamenta l phenomen a

1 0A n investigatio

n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m associate dwit h gas-soli dflows , a s wel l a s characteristic s o f selecte dgas-soli dflo w system s includin g dilut e transpor t o r pip e flow o f

gas-soli dsuspensions . Similarly , Sevill e e t al . (1997 ) als o summarize dparticl e characterization , particl e mechanic s an dsoli dassembl y mechanic s i n gas-soli dflow. Wit h regar dt o the pneumati c conveyin g o f granula r biomass , Cu i e

t al . (2006 ) reviewe dstudie s into transportin g agricultura l grain s an dpul p fibre s as wel l a s relate dflo w measuremen

t technique s an dmodeling . Althoug h ther

e hav e bee n numerou s experimenta l an dtheoretica l studie s int o pneumaticall y conveyin g asingl e granula r material , the correspondin g experienc e an dresult s ar e no t adequat e t o b e use dt

o solv e fh e previousl y discusse dtechnica l issue s suc h as equa l distributio n o f th e mixtur e fuel s fro mamai n t o severa l sub-pipe s i n apneumati c conveyin g system . Thus , i t i s necessar y t o study loca l informatio n o n th e soli dphase , suc h a s particl e spatia l distributio n an d soli dconcentratio n distributio n an dthe microscopi c mechanis mo f pneumati c conveying . Moreover , conveyin g pulverize dcoa l wit h biomas s ca n b e considere das aspecia l gas-soli dflow whos e soli dphas e consist s o f tw o o r more type s o f

soli dparticles . Th e objectiv e o f thi s chapter

i s t o stud y the differen t

influence s o n th

e particl e dynami c propertie s o f pulverise dcoa l an d granula r biomas s i n adilut e horizonta l gas-soli dpip e flow an dt o classif y thei r similarit y b y analysin g fh e characteristic s ofth e dimensionles s parameters . 2. 2 NUMERICA L MODE L AN D FLUI D CONDITION S 2.2.1 Discrete

Phase Model for gas-solid

simulations Recen t rapi dprogres s i n the theoretica l an dexperimenta l stud y o f turbulenc e modulatio n ha s le d t o grea t progres s i n understandin g som e basi c mechanism s o f gas-soli dpip e flow , whic h ca n b e normall y modelle db y th e Volum e o f Flui d(VOF ) model , Euleria n model s an dDiscret e Phas e Model s (DPM) . Ther e i s als o amode l calle dCFD-DEM , o r the Combine dContinuu man d Discret e Metho d(CCDM) , i n whic h th e motio n o f the soli dphas e i s describe db y th e Discret e Elemen t Metho d(DEM) . Ever y particl e o f th e soli dphas e i s tracke db y applyin g Newton' s law s o f motion . Correspondingly , the ai r phas e i s considere da s acontinuu mflui db y usin g Navier-Stoke s equation s i n the traditiona l Computationa l Flui dDynamic s (CFD ) manner . (Tsuj i Y. , 1993 ; Crappe r

M. , 2006 ; Ch u K.W . an dY u A.B. , 2007) . Sinc e the soli dvolum e fractio n i n dilut e pneumati c conveyin g i s very smal l (les s than 10%) , the effec t cause db y inter-particl e collision s i s usuall y ignore di n the numerica l simulations . Compare dwit h the Eulerian-Euleria n Model , the DP M mode l consider s asoli dphas e consistin g o f particle s randoml y disperse di n an isotropi c fluid . Thei r trajectorie s ar

e compute db y solvin g th e equation s governin g movemen t o f th e soli dphas e i n aLagrangia n fram e o f reference . I n contrast , th

e conveyin g ai r

i s regarde da s acontinuou s phas e whos e transpor t equation s ar

e

1 1Chapte r2 - Classifyin

g th e characteristic

s o f granula r biomas s an d pulverise

d coa l b y CF D solve di n an Euleria n fram e o f reference . Thi s mode l i s mor e appropriat e fo r trackin g ever y particl e trajectory i n th e fluid . T o dea l wit h phas e interactions , thre e regim e type s comprisin g one-way , two-wa y an dfour-wa y couplin g calculation s betwee n fh e soli dphas e an dga s phas e ca n b e classifie db y soli dvolum e fractio n les s than 10" 6 , large r tha n 10" 6an d beyon d0.1 % respectivel y (Elghobashi , 1994) . I n thi s work , DP M simulation s ar e use dt o selec t

th e two-wa y couplin g fo r

dilut e pneumati c transportation , an dtw o additiona l force s besid e the dra g forc e ar e t o b e considered . The y are th e virtua l mas s forc e require dt o accelerate th e flui dsurroundin g th e particl e an dthe Saffma n lif t forc e du e t o shear . Th e detaile dtransportatio n equation s o f DP M can b e foun di n Fluen t

Use r Guid e (Fluen t

Inc. , 2006) . 2.2. 2 The k-e turbulence

model Fo r singl e phas e flow , n o singl e turbulenc e mode l i s universall y accepte da s bein g superio r fo r al l classe s o f

problem . Th e k- e mode l ha s bee n widel y an d successfull y applie dfo r singl e phas e turbulent flow (ga s o r

liquid) , althoug h there ar e als o other

method s lik e direc t

numerica l simulatio n (DNS) , large-edd y simulatio n (LES) , an d discrete-vorte x simulatio n (DVS ) unde r development . Tabl e 2. 1 DP M mode l setup Typ e Choice s Solve r -v

* Segregate

d solve r Space : 2 D o r 3 D < • Stead y Turbulenc e modelfk- s Model ) Mode

l Constants

: C m u=0.084

5 C , =1.42C 2 =1.6 8 RN G options : Differentia

l viscosit y mode l Near-wal l treatment

: standar

d wal l function s < - Ful l buoyanc y effect s Discret e phas e optio n Interactio n wit h continuou

s phas e •f rUpdat e DP M source s ever y 1 5 flo w iteration s -v - Saffma n lif tforc e Two-wa y turbulenc

e couplin g Gravit y -y

> th e negativ e directio n o f y axi s * Value

: 9.8 1 m/s

2 Wal l collisio n mode l -4

- Reflectio

n •v - Reflectio

n coefficient

s o f nonna l an d tangentia l direction s ar e 1 • Roughnes

s constant : 0. 5 "v - Roughnes

s heigh trange s fro m 0 t o 2.3 2 m m Th e modificatio n o f

the ga s turbulenc e i n particle-lade n flow s i s no t wel l understoo dunti l now . Man y factors , suc h as particl e size , density , an dvolum e fraction , hav e been identifie da s havin g muc h influenc e o n th e turbulenc e intensity . Fo r example , experimenta l dat a(Tsuj i e t al. , 1984 ; Gore e t al. , 1989 ) sho w tha

t larger particle s ten dt

o enhanc e th e turbulenc e an dsmalle r particle s attenuat e it . I n general , the k- s turbulenc e mode l has bee n widel y use dt o describ e the ai r phas e i n gas-soli dflo w du e t o thi s mode l havin g bee n successfull y applie dfo r singl e phas e flo w (ai r o r

1 2



## VES01704 7A n investigatio

n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m liquid) . Th e k- e mode l assume s tha t th e flo w i s full y turbulen t an disotropic , an dtha t the effect s o f molecular

viscosit y are negligible . Nowaday s the k- e mode l ha s bee n develope dinto the Standard k- e Model , the Realizabl e k- e mode l an dth e Renormalizatio n Grou p (RNG ) k- e Model . Al l thes e three model s hav e asimila r approach , includin g transpor t equation s fo r

th e turbulen t

kineti c energ y (k ) an dit s rate o f dissipatio n (s) . Th e majo r difference s li e i n the equation s use dfo r calculatin g turbulen t

viscosit y an dthe expressio n o f the generatio n an ddestructio n term s i n th e g equation . Compare dwit h th e othe r tw o models , the Standardk- s Mode l i s relativel y simpl e t o implement , lead s t o stabl e calculation s tha t converg e relativel y easily , an dgive s areasonabl e predictio n fo r

man y flows . It s disadvantage s ar e tha t i t give s poo r

prediction s fo r

swirling , rotatin g an dstrongl y separatin g flows. Sinc e ou r studie s focu s o n the propertie s o f dilut e phas e granula r material s i n ahorizonta l pipe , th e k- e mode l i s selecte dfo r describin g ai r

phas e i n ou r numerica l simulations . Th e parameter s o f DP M setu

p i n Fluen t

6.2. 6 ar e briefl y liste di n Tabl e 2.1 . 2.2.3 Numerical

convergence

criteria A solutio n i s normall y assume dt o b e convergen t

whe n the su mo f

it s normalize dresidual s (fo r example , mass , velocit y components , turbulen t kineti c energies , turbulen t an ddissipatio n energies ) i s les s tha

n aspecifie dsmal l tolerance . Thi s toleranc e i s usuall y se t t o 1/1000 b y default . I n som e cases , Kohe n e

t al . (1994 ) an dHube r

e t al . (1998 ) foun dtha

t residual s were no t

suitabl e fo r us e a s acriterio n du e t o thei r oscillatin g a

t eac h couple dcalculation . Fo r thi s reason , the y advise dtha

t th e evolutio n o f

th e stream-wis e ga s velocit y profil e a t severa l referenc e position s shoul db e use das th e convergenc e criterion . I n thi s work , mos t numerica l solution s ar

e use dwit h the standar

dresidual s criterion . I n case s wher e the residual s jum p o r oscillate , the convergenc e i s determine db y the evolutio n o f the stream-wis e ga s velocit y profil e a t seve n specifi c points . 2.2.4 Model geometry

and mesh Grids I n order t o provid e futur e comparison s betwee n th e numerica l result s an dth e experimenta l data , th e domai n o f

ou r numerica l mode l i s simila r t o the dimension s o f

th e horizonta l part

o f the la b pilo t rig, whic h wil l b e discusse di n detai l i n sectio n 3.2 . Figur e 2. 1 show s both the sketc h o f the rig an dthe mes h grid s o f th e numerica l model . Th e rig i n Figur e 2.1(a) i s apneumati c conveyin g syste mwit h positiv e pressure includin g afan , acyclon e an dsevera l glas s pipes . Figure s 2.1(b ) an d(c ) sho w the tota l lengt h o f th e numerica l mode l an dth e cross-sectiona l mes h gri da t the mode l inlet , whic h ar e meshe db y employin g adjustabl e boundary-fitte dcoordinat e grid s respectively . Th e distanc e o f the first

cel l adjacen t

t o the wal l i s se t

t o 0.5m mi n orde r

t o

1 3



## VES01704 8Chapte r2 Classifyin g th e characteristic s o f

granula r biomas s and pulverise d coa l b y CF D investigate loca l fluidbehaviou r i n the pip e boundar

y region . Th e whol e domai n i s meshe dinto 0. 6 millio n cells . Th e origi n poin t o f the referenc e coordinat e i s locate da t th e centr e o f the pip e inle t wher e y positiv e axi s i s opposit e t o gravity an dz axi s i s alon g pip e radia l direction . Th e x positiv e axi s i s alon g fluidHow direction ,
(b ) I.=3000mm . i n x axi s x



### i

(a ) Th e la b ri g (c ) pip e inle t (t)>B()mm ) i n th e plan e o f Oy z Figur e 2 . 1 Experimenta

l rig (a ) an d th e mes h grid s o f th e numerica

l mode l (b, c) . (Pleas e not

e tha t th e scal e facto r

o f ever y diagra mi s differen t

fo r clarity an

dth e syste mcoordinat

e i s locateda t th e pip e inle t

centre. ) 2.2.3 Flow Conditions

and Selecting

Numerical

Parameters I n orde r t o b e abl e t o exten dth e experimenta l result s use dt o meaningfu l engineerin g applications , som e dimensionles s number s suc h a s Reynold s number , Froud e number an dStoke s numbe

r hav e been use dfo r

characterizin g the dynami c similarit y between th e pilo t ri g an dth

e large-sal e pneumati c conveyin g syste mi n apowe r plant . Thes e three essential parameter s ar e individuall y expresse da

s 

### pUD

R e 

### Fr= u (2.1 )


### st = ?> D 

### > v 

### l&pD wher e p , u an dU ar

e density , dynami c viscosit y an dvelocit y fo r ai r phas e separately . D i s pip e diameter . Li s acharacteristi c lengt h descriptiv e o f

th e flow fieldandi s usuall y define da s bein g equal t o pip e diameter

fo r pip e flow research . D pandp par e particl e diamete r

an dparticl e densit

y respectively .

1 4



## VES01704 9Al l investigatio n o f particl e dynamic s i

n a dilute phase pneumati c conveyin g system (iidding s an dArouss i (2004 ) indicate dtha t keepin g th

e Froud e numbe r

(base do n th

e pip e inne r diamete r a s th e referenc e length ) constant coul dmak

e th e pip e frictio n behaviou r o f the experimental rig simila r t o tha t o f afull-scal e powe r

plan t pipe . Fo r

example , a25m/ s conveyin g velocity and(|)330m

m(inne r diameter ) pip e ar

e tw o normal operatin g parameter s use di n the dilut e pneumati c conveyin g system s o f apulverize dcoal-fire dpowe r plant . Ou r

attainabl e 12m/

s air conveyin g velocit y ca n attai n dynami c similarit y wit h the experimenta l ri g wit h 80mmI D pipes . I n addition , arelativel y hig h conveyin g ai r velocit y mus t

b e maintaine dfo r

dilut e phas e conveying . Th e typica l orde r o f ai r conveyin g velocit y i s about 10-1 2 m/

s fo r fine powder s lik e pulverize dfue l an dwhea t flou r an d14-1 6 m/s fo r

fine granula

r material s lik e granula

r suga r and pearlite . I f

the conveyin g velocit y drop s b y mor e tha n 1 0 or 2 0 percent

i n the pipeline , i t

i s likel y t o caus e ablockag e proble m(Mills , 2004 , p429) . Thu s th e ai r conveyin g velocit y i s t o be i n th

e rang e o f 10~48m/ s i n our

simulations .



### 2 0 5 0 10 0 50 0 100 0 500 0

Mea n particl e siz e (|xm ) Figur e 2. 2 Geldart' s classificatio n o f fluidizatio

n behaviou

r forfluidization wit h ambien

tai r(Mills , 2004

) Accordin g t

o thei r ai r retentio n properties , Geldart (1973 ) classifie dgranula r material s int o fou r distinc t group s A , B , C an dD b y usin g densit y an daverag e mea

n diameter

i n hi s fluidization research . Th e experimental result s o f Mill s (2004 ) confirme dtha t th e material s i n group A hav e ver y goo dretentio n propertie s an dthe material s i n group C hav e very goo dpermeability . A s such , granula r material s o f

group A andC ar

e suitabl e t

o b e pneumaticall y transporte deither i n th e dens e o r dilut e phase . Biomas s density varie s fro m10 0 kg/m 3 fo r

straw t o 70 0 kg/m 3 fo r

fores t

1 5Chaplc r2 Classifyin g ih e characteristic s o f

granula r biomas s an d pulverise d coa l b y CK D har dwoo dan

dcoa l densit

y range s fro m110

0 kg/m 3 fo r

low-ran k

coa l t o 233 0 kg/m 3 fo r

hig h densit y pyrolyti e graphite . The pulverize dcoa l use di n moder n pulverize dcoal-fire dpowe r station s i s normall y les s tha n 1 lOu mi n size . However , the granula r biomas s consume di n many demonstratio n co-firin g powe r plant s i s usuall y filtere dt o b e les s tha

n 3m mb y a6 mes h siev e before transportatio n (NETBIOCOF , 2006) . Considerin g th e blockag e ris k

due t o transportin g oversiz e granula

r biomas s mixe dwit h pulverize dcoa l i n acommo n pipe , amore suitabl e granula r biomas s shoul db

e les s tha n 1m mi n siz e (equivalen t

diameter

o f asphere ) accordin g t

o Geldart' s Char

t (Figur e 2.2) . I

n addition , glas s bead s wil l b e use dt o simulat e th

e gas-soli dflo w o f th e mixtur e fuel s i n th

e la b experiments . A s such , th e numerica l simulation s wil l investigate th e dynamical propertie s o f thre e material s (coal , woo dan dglas s beads ) o f differen t

size s i n a horizonta l straigh t

pipe . Th e detaile dnumerica l parameter s ar e liste di n Tabl e 2.2 . Tabl e 2. 2 Numerica

l parameter

s Typ e Parameters Value air conveyin g velocity (U a , m/ s ) 10,15,18,20 , 24 , 30,4 8 Pip e diamete

r (D , mm ) 8 0 Pip e roughnes s HeightfA , mm ) 0,0.08 , 0.16,0.32,0.67 , 1.31,2.3 2 relativ e roughness(A/D ) 0 , 0.1% , 0.2% , 0.3%,0.83% , 1.6% , 3.3 % loadin g rati o (kgsVkgs-' ) 0.0 1

particl e glas s densit y (kg/m 3 ) 250 0

particl e glas s diamete r (um) 20 , 40 , 60 , 100 , 200 , 300 , 450 , 50 0

particl e glas s shap e Spherica l
particl e coa l densit y (kg/mJ ) 155 0 particl e coa l diamete r (pm ) 10 , 20 , 30 , 35 , 40 , 50 , 60 , 70 , 80 , 100 ,

200 , 30 0 particl e coa l shap e Spherica l particl e Woo d

chip s densit

y (kg/m 3 ) 18

5 particl e Woo d

chip s equivalent

diamete

r (pm ) 100,146,204,296,430,581,726,871,101 6 particl e Woo d

chip s Coa l diamete r with th e sam e Stoke s numbe

r (um) 29 , 50 , 70 , 100 , 150 , 200 , 250 , 300 , 35 0 particl e Woo d

chip s Shape spherical Feedin g positio n (m ) A t th e pip e inle t

(x=0) Feedin g Initia l velocit y Zer o (stati c injection ) Feedin g parcel s 3 D 450 0 Feedin g parcel s 2 D 20 0 Discrete phase boundar y conditio n Th e elasti c mode l o f particle-wal l collisio n Bot h th e norma l coefficien t

an dtangentia

l coefficien t

ar e equa l t o 1 . 2. 3 RESULT S AN D DISCUSSIO N Numerica l simulation s have bee n performe dfo r

differen t

set s o f value s o f

th e parameter s i n Tabl e 2.2 . Al l particle s ar e injecte dhomogeneousl y an dstaticall y (zer o initia l velocities ) fro mth e pip e inlet . I

n some fluidconditions , i t wa s foun dtha

t th e residual s o f

ai r turbulent

kineti c energ y

1 6A n investigatio n o f particl e dynamic s i

n a dilut e phase pneumati c conveyin g system Ik ) andit s rat

e o f dissipatio n (i; ) may not hav e bee

n convergen t

t o b e les s tha

n 1/1000 , whic h i s Ih e defaul t convergent

valu e fo r

eac h residual , althoug h th e other fou r residual s (continuity an d thre e component s o f

ai r velocity ) hadme

t the convergenc e criteria . Fo r thi s case , th

e criteri awer e mod i tie dt o detennin e th

e evolutio n o f

ai r velocit y profil e a

t the nin e referenc e points . Th e simulation s were regarde da s bein g convergent

whe n th e velocit y profil e remaine dstead y afte r a finit e number

o f iterations . Th e typica l evolutio n o f ai r velocit y profile s a

t the nin e referenc e point s i s show n i n Figur e 2.3(a) . Thes e nin e point s ar e equall y distribute da t x=2.0 mo n the vertica l lin e alon g pip e radiu s in y direction . Th e ai r velocit y profil e i s observe dt o be develope d steadil y afte r

the 60 , htwo-couplin g computation , as show n i n Figur e 2.3(a) . Th e relativ e erro r o f air velocit y relativ e t

o it s averag e value a

t th e nin e referenc e point s fel l clos e t o zero afte r

80 0 iteration s i n Figur e 2.3(b) . Thus , the numerica l computation s ar e considere das bein g convergent afte r 80 0 iteration s fo r

th e current flui dconditions .
O S < - r•

-0.5 ; - - ' ' 1 '• i

0. 5 0. 6 0. 7 OB 0 9 1 1 1 1. 2 1 3 1.

4 \

10 0 20 0 30 0 40 0 5i) 0 CO O 70 0 BO O M O 1!>0

O U,,'U ( 1 ilwati'M i (a ) (b ) Figur e 2. 3 Th e convergenc

e behaviou

r o f numerica

l simulations

, (a ) th e evolutio n ofth e stream-wis

e ai r velocit y profil e acros s th e pip e a tx=2.0 m o n seve n selecte d iteratio

n number

s o f two-couplin

g computation

s (b ) th e developmen

to f th e relativ e erro ro f th e velocit y t o it s averag e valu e versu s numerica

l iteratio n o n nin e referenc

e points . 2.3.1 Particle

trajectories

in the pipe Numerica l simulation s were firstl y performe dt o explor e particl e trajectorie s i n th e pipe . Figur e 2. 4 onl y show s trajectorie s o f glas s bead s (100pm ) injecte dalon g th e y axi s i n asmoot

h pip e (rj)80mm ) under ai r conveyin g velocit y 24m/s . Here , Rmean s pip e radiu s andy stand s fo r th e fee dpositio n o f

aparticle . Bot

h figure s i n Figur e 2. 4 clearl y displa y th e phenomeno n o f

gravity settling . I

t show s tha

t th e pea k position s o f

particle s graduall y decreas e alon g th e pip e due t

o the gravity force . Whe n the y hi t th e pip e surface , particle s wil l bounc e andmov e alon g th e pip e b y saltation . Sinc e particle s ar e injecte da

t differen t

position s o n the pip e inlet , th e trajectorie s ofth e particle s wil l not

have an y axia l symmetry propert y a t th e particl e impac t

poin t on the wal l due t

o th e curve dsurfac e o f

the pipe , eve n thoug h a n elasti c particle-wal l collisio n mode l i s applie di n th e calculations . I

n Figur e 2.4(b) , w e can clearl y observ e tha t particle s injecte dclos e t o the wal l hav e ajumpin g pat

h fro mtheir

fee dposition s distinc t

fro mother s i n the mainstrea mregion . Thi s

1 7Chapte r 2 Classifyin g Ih

e characteristic s o f

granula r biomas s and pulverise d coa l b y CF D indicate s tha

t aparticl e clos e t

o th e wal l mus t

be acte don b y a

n additiona l forc e i n the y direction , an dtha t thi s forc e i s larger

tha n the gravit y forc e on the particle . I n th e boundar

y region , thi s additiona l forc e i s th

e Saffma n lif

t forc e induce db y flo w velocit y gradient s i n the y direction . I t ca n be expresse da

s (Fa n L.S. , 2003) .


### oy (2.2 ) wher e F s i s th

e Saffma n force , the constan t K i s 6.4 6 (kgmV 3 ) , U ai s the ai r velocit y an dU pi s th e particl e velocity , p i s th e ai r absolute viscosit y an dv i s the ai r kinemati c viscosity . Th e influenc e o f

th e Saffma n forc e on particle s wil l b e discusse di n th e followin g thre e section s (2.3.2-4 ) i n term s o f

variation s o f

ai r conveyin g velocity , pip e roughnes s an dparticl e size .

3 5 3 0 2 5 2 0 (a ) 3 D trajectories (b ) Trajectorie s in y directio n Figur e 2. 4 Particle s trajectorie

s (runnin g directio n fro m righ tt o left ) (Glas s beads , d p =100um , U a =24m/s,<|)80mn

i smoot h pipe , soli d loadin g mas s rati o 1 % kgs'Vkgs"'

) Figur e 2. 5 show s the trajectorie s o f tw o particle s injecte da t tw o point s o f

y/ Requa

l t o -0.9 0 an d -0.9 9 respectively , whic h ar e clos e t

o the pip e bottom . Thes e trajectorie s wer e selecte dfro m thos e i n Figur e 2. 4 fo r

clearl y visualizin g particl e trajectorie s i n the boundar y region . Observin g tw o selecte dtrajectorie s i n th e y directio n (Figur e 2.5a) , w e ca n see tha t th e particl e injecte da

t the positio n o f

y/R=-0.9 9 ha

s adistinc t

jum p a t the star t point , whic h i s due t

o it s Saffma n forc e bein g large r

tha n it s gravity force . O n th e contrary , the particl e injecte da t th e positio n o f y/R—0.9 0 doe s not

hav e suc h afeature . Behin dth e firs t particle-collisio n point , the Saffma n forc e actin g o n particle s shoul db e decrease dsinc e particle s hav e been accelerate di n the distance , whic h i s mor

e tha n x/D=15 . However , the secon dpea k i n the y directio n i s higher tha n the firs t one o n eac h particl e trajectory , whic h indicate s tha t th e reflecte dU p y(particl e velocit y i n the y direction ) i s large

r tha n th e impacte dU p ya

t the collisio n point . O n the other hand , the trajectorie s o f tw o particle s i n th

e z directio n (Figur e 2.5b ) display s the fac t tha t thei r position s i n th

e z directio n begi n t

o b e awa

y fro mthei r

feedin g position s o f

z= 0 behin dth

e firs t particle-wal l collisio n point . Th e abov e phenomen aca n b e als o explaine db y the variation s o f U p x(th e axia l

1 8A n investigatio n o f particl e dynamic s i n a dilut e phase pneumati c conveyin g syste m particl e velocity ) andU p y(th e vertica l particl e velocity ) i n Figur e 2.5(c ) an d(d) fo r tw o selecte d particle s separately . Accordin g t o th e trajectory befor e the firs t particle-wal l collisio n poin t Figure 2. 5 (c ) and(d) , th e similarit y fo r

bot h particle s lie s i n tha

t they ar e accelerate dt

o hav e a n increasin g U p xin Ih

e x axi s fro mthe stati c stat e a t the feedin g positions , l n contrast , th e differenc e between tw o particle s i s tha t the particl e injecte da

t the point

r/R=-0.9 9 has obtaine da positiv e U p ywhic h make s i t suspende di n the y directio n (a s show n i n Figur e 2. 5 (c)) . Th e particl e injecte da

t th e poin t r/R=-0. 9 fall s dow n du e t o gravit y forc e i n the y direction . Whe n a particl e hit s th

e pip e wall , w e can clearl y se e tha t no t onl y th e sig n o f

U p yi s change dfro mth e negativ e t

o th e positiv e bu

t als o the magnitud e o f

U p yi n the reboun ddirectio n i s larger tha n tha t i n th e impac t direction . Consequently , the secon dpea k i n aparticl e trajector

y i s highe r

tha n th e first pea k in the y direction . In addition , compare dwit h tha t i n the impac t

direction , th

e magnitud e o f

U p xdecrease s alittl e afte r particle-wal l collision . Thi s indicate s tha t some particl e momentu mo n th

e x axi s ha s bee n transferre dt o tha t i n th e y directio n durin g particle-wal l collision , sinc e th

e normal lin e o f

the particle-wal l elasti c collisio n i s alon g apip e radiu s rather tha n the y axis .
y/R.-O.O O y/R=-U9 0 l j

4 5 4 0 3 5 3 0 2 5 2 0 ' 5 I

D 5 0 4 b 4 0 3 5 3 0 2 5 21 ) 15 ' 0 (a ) Trajectorie s i n y directio n (b ) Trajectorie s in 7. directio n Panicl e peele d a ty/R=-0.9 9

(c) Fo rth

e particl e injecte d a

ty/R=-0.9 9 (d) Fo rth e particl e injecte d a ty/R=-0.° 0 Figur e 2. 5 Trajectorie

s an d th e variation

s o f (U px , U p) ) fo

r tw o selecte d particle

s Th e abov e discussion s sho w tha t bot h Saffma n forc e an dparticle-wal l collisio n on pip e wal l exer t a n importan

t influenc e o n particl e behaviou r a t the pip e boundary . I n order t o onl y

1 9Chapte r2 Classifyin g th e characteristic s o f

granula r biomas s and pulverise d coa l b y CF D investigate th

e effec t ofth e Saffma n force , the followin g thre e section s fro m2.3. 2 t o 2.3. 4 wil l presen t th e numerical simulation s i n tw o dimension s fo r clarity , correspondin g t o the z= 0 sectio n in 3 D mod

e fo r 100p mglas s beads . I

n thi s case , th

e norma l lin e o f

particle-wal l collisio n i s alon g th e y axi s andther

e i s no momentu mexchange damon g thre e component s o f aparticl e velocit y durin g particle-wal l collision . 2.3. 2 The effect of air conveying

velocity

-0.8 2 -0.8 4 -0.8 6 -0.8 8 S 4.9 1 -0.9 2 -0.9 4 -0.9 6 U a =18nV s U a =20nV s U a =24m/ s U a =30m/ s U=48m/ S

1 5 2 0 2 5 3 0 3 5 4 0 X/ D Figur e 2. 6 Particl

e trajectorie

s wit h differen

tconveyin

g velocitie

s (lOOu m glas s beads , (j>80m m smoot

h pipe , soli d loadin g rati o l% , 2 D model ) I n th e 2 D mod

e jus t a s a t the z= 0 sectio n i n th

e 3 D model , 20 0 parcel s ( aparce l mean s agroup o f particle s with th

e sam e diameter

injecte da

t th e sam e position ) wer

e equall y injecte dove r th e pip e inlet . Th e thre e influence s o f conveyin g velocity , wal l roughnes s an dparticl e siz e ar e investigate dfo r

explorin g particl e characteristic s i n the boundar y region . Changin g onl y ai r conveyin g velocit y whil e keepin g othe r parameter s constant , the numerica l result s o f ai r velocit y effect s o n th

e boundar

y regio n ar

e show n i n Figur e 2.6 . I t show s th

e trajectorie s o f

asingl e particl e injecte da

t the positio n o f

r/R =97.5 % wit h differen t ai r conveyin g velocities . Compare d wit h othe r points , a

n injectio n poin t

i n th e boundar

y regio n i s clos e t

o th e pip e botto mwhere the Saffma n forc e shoul db

e stron g du e t

o th e stron g gradient

o f ai r velocit y on the y axis . Observin g the firs t pea k o f th e trajectorie s i n Figur e 2.6 , w e can se e tha t th e particl e jump s highe r an d higher when ai r

conveyin g velocit y increase s fro m1 6 t o 30m/s . However , the particl e ca n jum p n o higher

whe n the ai r

conveyin g velocit y i s more tha n 30m/'s . I

n thi s case , i t

follow s the previou s highes t

path . I n summary , astronger

ai r conveyin g velocit y generall y benefit s b y liftin g aparticl e highe r

fro mth e boundary regio n towar dthe pip e mainstrea mfield, bu

t i t ca n not be lifte dmuc h highe r

whe n ai r

velocit y i s mor

e tha n acertai n value . Thi s valu e i s define das the critica l ai r

conveyin g velocity . Her e the valu e o f 30m/ s i s th

e critica l velocit y fo r

the curren t

fluid conditions . Not e tha

t the numerica l simulation s hav e been carrie dou t fro m1 6 t

o 4 8 m/ s a

t 2m/ s

2 0



## VES01705 5Ai i investigatio n ol ' particl e dynamics in adilut e phas e pneumati

c conveyin

g syste m increment s andthe dat

ao f onl y liv e typica l ai r

velocitie s ar

e show n i n Figur e 2. 5 fo r clarity . 2.3. 3 The effect of pipe roughness The effec t

o f pip e roughness , keepin g other parameter s constant , i s no w considered . Th e effec t i s illustrate di n Figur e 2.7 , unde r th e condition s o f

transportin g 100p mglas s bead s b y a24m/ s ai r conveyin g velocit y i n a(j>80m mpipe . Thi s figur e show s th e trajectorie s o f asingl e particl e injecte da

t th e positio n o f

r/R=97.5 % wit h the differen t pip e roughnesses . W e observ e tha t a particl e i n th

e boundar

y regio n wil l b e returne dt o amuc h highe r

positio n fo r

increase s i n pip e roughness . However , whe n the pip e relativ e roughnes s i s mor e tha n 1.64% , the trajectorie s ofth e particl e ar

e the sam

e andthe particl e can n o longe r b e lifte dmuc h higher . W e cal l the valu e o f 1.64 % the critica l pip e relativ e roughnes s fo r the current

flui dconditions .

< ? > . A=0.20 % -0.7 5 :.

r" 4=0.40 % : J=0.S3

%

S -0.8 5

-0. 9 -0.9 5 ." ' . . • 

### 9

- 1 1 D 5 1

0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 Figur e 2 . 7 Particle

s trajectorie

s wit h differen tpip e roughnes

s height s (U a =24nVs , lOOu m glas s beads , <ji80m m pipe , soli d loadin g rati o I % . 2 D model) ) 2.3. 4 The effect of particle size
-0.84 ; , r- d p ,20 „ -0.8 6 • d 0 =40, , -0.8 8 d =100| I < i =300 ( 1 43. 9 d 3 =450 ( 1 E -0.9 2 : •:

• > -0.9 4 -0.96. ' I 

### i J

, -0.98 . • ' " •" 

### V 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 x/ D Figur e 2 . 8 Trajectorie

s wit h differen

tparticl e size s (U a =24m/s , glas s beads , <|)80m m pipe , soli d loadin g rati o 1% . 2 D model)) .

2 1



## VES01705 6Chapte r 2 Classifyin g th e characteristic s o f

granula rbiomas s and pulverise d coa l b y CF D Ii i general , th

e bigger aparticl e is , the stronger th e gravit y forc e actin g on it . Also , accordin g t o equatio n (2.2) , th

e large r aparticle , the stronger th e Saffma n forc e produced . A s such , th e suspensio n possibilit y o f aparticl e i n the boundar y regio n i s determine db y the relativ e magnitude o f

the gravity forc e an d th e Saffma n force s o n it . Figur e 2. 8 show s the effec t o f particl e siz e unde

r th e condition s o f

24m/ s ai r

conveyin g velocit y i n the tj >80m msmoot h pipe . I t show s th e trajectorie s o f asingl e particl e injecte da t th e positio n o f

r/'R~97.5 % wit h th e differen t sizes . Particle s fro m1 0 t o 450p ma

t a n increment

o f 1 0 u mhav e been investigated , bu t the particl e trajectorie s o f

onl y fiv e specifi c size s ar e show n i n Figur e 2. 8 fo r clarity . Basically , th

e bigge r aparticl e is . th

e highe r i t ca n b e suspende di f

it s siz e i s i n the rang e o f 10-100pm . Bu t

thi s phenomeno n wil l n

o longe r exis t whe n aparticl e i s larger than 100p.m . A s such , th e valu e o f 100p mi s define da

s critica l particl e siz e fo r the curren t

flui dconditions . A s indicate di n equatio n (2.2) , the Saffma n forc e in th e pip e boundar

y regio n wil l b e stronge r wit h increasin g ai r

conveyin g velocity , particl e siz e an d pip e roughness . However , th e critica l value s o f

thes e three parameter s ca n no t b e directl y deduce dfro mequatio n (2.2) . Th e thre e critica l parameter s explore db y th e numerica l result s wil l benefi t i n determinin g the minimu mai r conveyin g velocit y i n dilut e pneumati c conveyin g systems . 2.3.5 The characteristics

of particle

mean velocity

in terms of particle

Stokes Number Tabl e 2. 3 Particle

s Stoke s numbe r an d termina

l velocit y Coa l (1550kg/m 5 ) Woodchi p (185kg'm' ) Glas s (2500kg/m' ) d (um ) Stoke s Numbe r Termina l Velocit y U M(m/s ) d (um ) d (um ) 1 0 0.072 0.004 6 3 0 8 20 0.28 7 0.0183 5 9 1 6 3 0 0.64 5 0.040 8 8 8 24 4 0 1.14

7 0.071 8 117 3 2 5 0 1.79

3 0.110 3 14

6 4 0 60 2.58 1 0.154 8 17 5 48 70 3.51 4 0.203 5 20 4 5 6 80 4.58 9 0.254 6 23 3 6 3 90 5.80 8 0.3065 26 2 7 1 10 0 7.17 1 0.358 7 29 1 7 9 15 0 16.1 3 0.666 4 43 6 119 20 0 28.6 8 0.9472 58 1 15 8 25 0 44.8 2 1.2830 72 6 19 7 30 0 64.5 3 1.612 9 87 1 23 7 35 0 87.8 4 1.932 8 101 6 27 6 Stoke s Numbe r

(St) i s define da

s the rati o o f

particl e inerti at

o flui ddrag . I

t i s know n tha

t a particl e havin g asmal l Stoke s Numbe r ha s agoo dcapabilit y o f followin g the fluid . Sinc e granula r biomas s i s usuall y lighte r an d larger

tha n pulverize dcoal , th

e questio n whether

they hav e any simila r

characteristi c i n pipe s i s investigate di n thi s section . W e wil l us e the Stoke s

2 2



## VES01705 7A n investigatio n o f particl e dynamic s in a dilute phas e pneumati c conveyin g system Number t o classif y th e similarit y betwee n pulverize dcoa l an dgranula

r biomas s characteristic s i n th e directio n o f

flui dHo w andappl y th

e termina l velocit y (U p t ) fo r th e dimensionles s analysi s o f particl e velocitie s i n th e gravity direction . Th e detaile dequation s fo r calculatin g the termina l velocit y o f

aparticl e ar

e liste di n th e boo k

Processin g o f

Particulat e Solid s (Sevill e e t al. , 1997) . Tabl e 2. 3 show s value s o f S t an dU p lfo r

typica l sample s o f

pulverize dcoal , woo dchip s an dglas s beads . I n order t o addres s th

e similarit y o f

granula r biomas s an dpulverise dcoal , numerica l simulation s hav e bee n carrie dou

t on th e transportatio n o f

nin e kind s o f

mono-distribute dgranula r woodchip s (100~10l6pm ) and1 0 type s o f mono-distribute dpulverise dcoa l (10~150pm ) b y 10m/ s conveyin g ai r

with soli dmas s loadin g rati o 1 % i n ahorizonta l smoot h 4>80m mstraight

pipe . Eac h kin do f particl e wa s release dfro mth e pip e inle t with ahomogenou s distributio n acros s the whol e inle t area . Th e detaile dboundar y condition s an drelate dnumerica l parameter s ar e liste di n Table s 2. 1 an d2.2 . Her e w e hav e focuse dou r attentio n o n the analysi s o f th e mean particulat e velocitie s o f the soli dphase , sinc e the mea n quantitie s ar

e o f mor e interes t i n engineerin g applications .

| (a )

= 07 - ..

3 0 4

0 5

0 6

0 7

0 *

0 /JO

12 6 l o 2 0 3

0 4

0 6

0 60

* " 7

0 8

0 i/ O Figur e 2. 9 Th e evolutio n o f th e mea n particulat

e velocitie

s U p ) an d D p ) fo rpulverise

d coa l (U a =10m/s ; smoot

h pipe ; coa l particle s siz e 10~150gm ; soli d loadin g rati o 1% , 3 D model ) I n general , th

e mea n particulate horizonta l velocit y (U p x ) o n the x axi s or flui ddirectio n i s rendere ddimensionles s by the ai r conveyin g velocit y (U a ) an dth e mea n particulate vertica l velocit y (U p y ) o n th

e y axi s o r

gravit y directio n i s mad e dimensionles s b y it s terminal velocity . Th e development

o f thes e tw o dimensionles s velocitie s i s show n i n Figur e 2. 9 (a ) an d(b ) respectively . Th e evolutio n o f

th e horizonta l dimensionles s velocit y U p x / U ai n Figur e 2.9(a) show s the

2 3Chapte r 2 Classifyin g th e characteristic s o f

granular biomas s an d pulverise d coal b y CF D progressio n o f

th e soli dphas e fro mth

e acceleratio n regio n int o the full y develope dstate . Thi s proces s depend s on th

e mea n particulat e siz e o f

th e soli dphase . Th e larger the mea n particulat e size , th e longe r is th e acceleratio n distance. . I n acomparison , fin e particle s lik e thos e o f 10p m diameter hav e almos t

n o obviou s acceleratio n distanc e before the y attai n avelocit y equal t o tha t ofth e conveyin g ai r

(U a ) . Thi s agree s wit h th e theoretical predictio n o f Seville , (1997) , tha

t th e fine particle s hav e agoo dabilit y t o follo w the fluid . O n the contrary , particle s wit h alarge r mea n siz e suc h a

s 15 0 p musuall y hav e alonge r acceleratio n distanc e befor e attainin g thei r pea k velocitie s i n th

e horizonta l direction . Thei r horizonta l mea

n velocitie s subsequentl y begi n t o deceas e graduall y unti l the y reac h astead

y valu e whos e dimensionles s valu e i s equa l t o 0. 6 OV/u a ) . Wit h regar dt

o th e variatio n o f

th e vertica l dimensionles s velocit y U p y / U ai n Figur e 2.9(b) , w e ca n se e tha t the mea n particulat e vertica l velocitie s (U p y ) o f fine coa l particle s les s tha n 20p mi n diameter rapidl y develo p t

o thei r correspondin g termina l velocity . However , the mea n particulat e vertica l velocitie s o f

large r particle s more tha

n 80p mi n diameter

ten dt o zero afte r

they enter

th e full y develope dregion . Thi s indicate s tha t th e vertica l velocitie s o f thes e larger

particle s hav e equivalen t

possibilitie s o f

bein g i n the u

p o r dow n directio n wit h th e sam e absolut e velocit y o n the y axis .

(t o

Figur e 2.1 0 Evolutio n o f th e mea n particulat

e velocitie s U p van d U p yfo r woo d particle s (U a =10m/s ; smoot

h pipe ; Woo d chip s 100~1016|jm ; soli d loadin g rati o 1% , 3 D model ) Sinc e particle s wit h alo w Stoke s Numbe r (les s tha n 1 ) have agoo dabilit y t o follo w th

e flui dn o matte r wha t kind s o f

material s the y are , w e onl y focu s o n woodchip s wit h equivalen t diameter mor e tha n 100pm , correspondin g t o particle s wit h aStoke s numbe r > 1 (Tabl e 2.3) . Figur e 2.1 0 show s the variatio n o f

th e dimensionles s velocitie s o f the large r

woo dchips . A s wit h pulverise d

2 4



## VES01705 9A n investigatio

n o f particl e dynamic

s i n adilut e phas e pneumati

c conveyin

g syste m coal , the large r

granula r woodchip s compare dwit h the smalle r one s hav e alonge r

acceleratio n distanc e t o befor e attainin g full y develope dflow. Subsequently , thei r horizonta l mean velocit y reache s astead

y valu e whos e dimensionles s valu e (U p x AJ a ) i s als o equa l t o 0.6 . Th e average d value o f th e mean particulat e vertica l velocitie s fo r the large r

particle s als o rapidl y reache s zero . Summarizin g the foregoin g discussions , w e ca n classif y th e characteristic s o f the mean particulat e velocitie s i n the horizonta l an dvertica l direction s int o thre e type s b y Stoke s Number , a s liste di n Tabl e 2.4 . Thi s tabl e indicate s tha t th e particle s o f

th e differen t

material s hav e simila r dynami c characteristics , suc h a s particulat e mean velocitie s i n the horizonta l an dvertica l directions , i f

thei r Stoke s Number s ar

e equal . Empirically , i t

i s reporte dtha

t the sli p ratio , define di n term s o f th e mea n velocit y o f

the soli d phas e divide db y th e conveyin g velocity , i s usuall y aroun d0. 8 (Mills , 2004) . Thi s definitio n i s simila r t o the dimensionles s mean particulat e horizonta l velocit y i n thi s chapter i f the mea n velocit y o f

the particle s i s considere da s the soli dphas e velocity . Accordin g t o Tabl e 2.4 , the valu e o f 0.8U ai s th e media n value ofth e mean dimensionles s particl e velocit y i n the horizonta l direction . Sinc e w e us e mono-disperse dparticle s i n th e numerica l simulations , the sli p rati o o f the poly-disperse dsoli dphas e wil l var y i n the rang e o f (0.6~l)U adependin g o n its mea n particulat e size . I n the vertica l direction , particle s wit h Stoke s Numbe r les s tha n 1 ca n b e easil y suspende di n aflui dsinc e thei r vertica l velocitie s equa l th e correspondin g termina l velocities . However , fo r

particle s wit h Stoke s Numbe r mor e than 3.5 , the average dvalue o f particl e velocit y i n the y directio n tend s t o b e zero . Thi s implie s tha t thes e particle s bounc e o r slid e alon g th e pip e wit h ahig h frequenc y o f particle-wal l collisions . Tabl e 2. 4 Th e mean axia l particl e velocit y i n th e full y develope

d regio n Stoke s Numbe r <0. 6 0.6-3. 5 >3. 5 1 0.6- 1 0. 6 u„ v /u , -

1 -1-

0 0

2. 4 CONCLUSION S A detaile danalysi s o f

thre e factor s (ai r

conveyin g velocity , pip e roughnes s an dparticl e size ) tha t influenc e particl e trajectorie s i n the boundary regio n ha s bee n performe db y carryin g out numerica l simulation s usin g the Discret e Phas e Mode l i n Fluen t 6.2.16 . Th e numerica l result s demonstrat

e that th e Saffma n Forc e play s a n importan t

facto r i n adilut e pneumati c conveyin g system , especiall y fo r

determinin g whether

aparticl e wil l b e re-suspende dfro mth e boundary region . Thi s analysi s show s tha t there exis t

thre e critica l parameters : th e critica l ai r conveyin g velocity , th e critica l particl e siz e an dthe critica l pip e relativ e roughness . Generally , increasin g any on e o f

ai r conveyin g velocity , pip e roughnes s an dparticl e siz e wil l improv e the chance s o f a particl e bein g re-entraine dfro mth e boundary region , i n agreement wit h equatio n (2.1 ) whic h ca n

2 5



## VES01706 0Chapte r2 - Classifyin

g th e characteristic

s o f granula r biomas s an d pulverise

d coa l b y CF D b e use dt o calculat e the Saffma n force . I n addition , the numerica l result s als o revea l tha t the critica l value s o f

eac h o f thes e thre e parameter s wil l represent s alimi t beyon dwhic h an increas e give s no improvemen t

i n particl e re-entrainment . Th e characteristic s o f

the dimensionles s mean particulat e velocit y i n th e horizonta l an dvertica l direction s hav e als o been investigated . Th e particl e mean velocitie s o f th e differen t

material s ca n b e classifie dint o thre e type s i n th e horizonta l an dvertica l direction s non-dimensionalisin g as the Stoke s Numbe r

o r dividin g b y termina l velocit y respectively . Th e numerica l result s indicat e tha t particle s wit h Stoke s Numbe r les s than one hav e amean velocit y equa l t o the ai r conveyin g velocit y i n the horizonta l directio n an damean vertica l velocit y equa l t o th e termina l velocit y i n the full y develope dregion . Correspondingly , fo r large r particle s wit h Stoke s Numbe r mor e tha

n 3.5 , thei r mea n dimensionles s velocit y U p x / U atend s toward s 0. 6 i n th e horizonta l directio n an d thei r mean dimensionles s velocit y U p y / U aessentiall y zer o i n th e vertica l direction . Th e mea n dimensionles s velocitie s o f particle s wit h Stoke s numbe r betwee n 1 an d3. 6 ar

e i n th e rang e o f 0.6- 1 i n th e horizonta l directio n an d-1- 0 i n th e vertica l direction . Th e effect s o f

non-spherica l particle s an dinter-particl e collision s ar e ignore di n thes e numerica l simulations . Th e latter

effec t wil l b e studie db y usin g CFD-DE M (Discret e Elemen t Method ) couplin g simulation s i n Chapte r 7 .

2 6



## VES01706 1

# Chapte r 3 Extendin g Lase r Dopple r Anemometr y fo r particl e flo

wmeasuremen t i n pipe s

An extended

LaserDopplerAnemometry (LDA) technique has been developed to measure the distributions ofparticle velocities and particle numberovera whole pipe cross section in a dilute pneumatic conveying system. The first extension concentrates on the transform matrix for predicting the laserbeams'cross point in a pipe according lo the shift coordinate of

the 3D computer-controlled

traverse system on which the probes of the LDA system were mounted. The second focuses on the properLDA sample rate forthe measurement of gas-solid pipe flow with polydisperse particles. A suitable LDA sample rate should ensure that

enough data is recorded in the measurement

interval to precisely calculate the particle mean velocity orotherstatistical values at

every sample point. The present study explores the methodology as well as fundamentals of

measurements, using a laserfacility, of the local

instantaneous density of particles as a primary standard.

3. 1 INTRODUCTIO N Th e techniqu e o f

Lase r Dopple r Anemometr y (LDA ) whic h i s als o referre dt o Lase r Dopple r Velocimetr y (LDV ) ha s bee n develope dmor e tha n thirty years , sinc e i t

wa s invente db y Ye h an d Cummin s i n 1964 . I

t i s non-intrusiv e wit h hig h accurac y an dver y hig h spatia l resolutio n an dha s bee n extensivel y applie dfo r fluidmechanic s measurements . Befor e introducin g the extende d technique s o f

LDA , w e briefl y revie w th e principl e o f LD A an dit s application s i n gas-soli dflow. 3.1.1 The

brief principle

of LDA Th e Laser-Dopple r

metho di s base do n th e measurement o f th e Dopple r

shif t o f lase r ligh t scattere dfromsmal l particle s carrie dalon g wit h the fluid. Th e basi c component s an dadua l bea m structure o f

aLD A syste mar

e illustrate di n Figur e 3.1 . Thi s syste musuall y comprise s a



## VES01706 2A n investigatio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m continuou s wav e Argon-Ion-iaser , fibre optics, afrequency shifte r an dsevera l lense s t o construc t a n optica l probe , whic h ca n produc e ameasuremen t volum e o r

interferenc e fringe s forme dby

tw o beams with th

e sam e ligh t intensity an dadifferen t phas e modulate db y aBrag g cell . Th e siz e an dpositio n ofthi s ellipsoida l crossin g poin t i s dependen

t o n th e foca l length o f

the prob e fron t lens .

- * t*i(M i Th » pnnapW a o f Lase r Dopple r Anefnometr y S- ID A i s B m n irvn A M 1 npticiL rmwmv t(•fint i J ? W •iveslKiBliiV

j jdu c J O a

ta port n n ra w LUAca n oeuse d narfr+ft c tlquf l f w m h np o J u r - P S S I A I W rMHEuiWIN tpo-n :puMlHC l it* * . • • » w t• • • i

U tJWinVMICi.i l H>Hkolj LA JUlTt * w h w \KSV

S I M I -

trl - •iit.u'i i ku

r pift*ur ri i .i.!"*riT i ipi i iHanclrlrtr K p i IP * Vwtf l r j ;vih

- If" . crtt'r* . .rrf '

r Mii« ^ & ' I T r,- f

i * i"»n i .jinn- r • rhrbn~ k vitwacl-n* * jctj p i rarc y dw

> Fisar F lo w e rflo w it s

- _A phoiamuNipii v corven s W l>gh tnuntel y f

l jel i eiiu m to air e Lnca l wgn*! s whic h a n i

n Di m co n verte d to valoci' y inTorimilin n I n Pi e BS A prrx(5*K v ih e frKibencv o l it e 'mlwi g 'Kjhi ftVpnlr rirAq-jnney ! n prupo r jura l l u il v Dx m JBiout

j e l th e • tH.iU.UiTVI I flU M I h e processin g resu b ar e twide d tyn r RS A lir w <irrfrwMi > Ti m co m rx*->rn« ; of

+i » vnoct y vftctc

v ca rb n dcijjec l i»rm a anwusly , dapnrjn ^ o n in e syste n ronhqurativ i Figur e 3 . 1 Th e schemati

c diagra m o f alaser-Dopple

r anemometr

y (DANTEC , 2008

) I n Figur e 3.1 , i f

th e tw o beams wit h the sam e wavelengt

h X intersec t a t a n angl e G

, th e distanc e d r between the interferenc e fringe s can b e theoreticall y deduce das :
V (3.1 ) 

### 2 

### si n (6 7 2 ) Whe n aparticl e passe s through the measuremen t volume , the scattere dligh t wil l b e distribute d ove r th e whol e o f

space . Th e scattere dligh t i s characterize db y aDopple r shift , the Dopple r frequenc y f

, whic h i s proportiona l t o the velocit y component perpendicular

t o th e bisecto r

ofth e tw o laser beams . A n optica l fibr e mounte dbehin dth e fron t len s o f th e prob e i s use dt

o receiv e an ddelive r

th e scattere dligh t

t o aphotomultiplier . The n the intensity , phas e a s wel l a s the amplitud e fluctuatio n o f th e scattere dligh t

ca n b e detecte dan danalyze di n th e BS A signa l processor . I f

w e kno w th

e time t whic h aparticl e take s t o trave l the distanc e betwee n tw o fringe s (i t i s als o calle dth

e fring e spacing) , it s velocit y ca n b e directl y calculate db y equatio n (3.2) . u„ = 

### LL t (3.2 ) In thi s way , th

e task o f measurin g the velocit y o f aparticl e i s modifie dt o determin e th

e spen t tim e t o r frequenc y (f=l/1 ) o f

aparticl e passin g throug h th e fringe , whic h i s evaluate di n th e BS A signal processo r

b y usin g spectral analysis . Th e relationshi p betwee n the frequenc y an dparticl e

2 8



## VES01706 3Chapte r3 Extendin

g LD A fo r particl e flow measuremen

ti n pipe s velocit y i s give n as equatio n (3.3) . 

### /=^sin(% ) (3.3 ) Th e abov e explanatio n i s calle dth e Fring e mode l o f LD A i n whic h the Dopple r signa l i s interprete da s severa l singl e burst s intersperse dwit h period s o f low-powe r

sho t noise . Correspondingly , the principl e o f LD A ca n b e als o explaine db y the frequenc y demodulato r mode l i n whic h the Dopple r signa l i s considere dquasi-continuous . Th e detaile dcontent s o f thes e tw o model s wer e reviewe db y Buchhav e e t al . (1979 ) wh o deduce dthe mode l equation s an d summarize dth e physica l parameter s affectin g the Dopple r signal , suc h a s Dopple r ambiguity , bia s correction , refractiv e inde x effect s an dminimizin g an deliminatin g the effect s o f phas e fluctuations o n turbulenc e measurement . Sinc e avelocit y measure db y LD A i s calculate dfro mthe Dopple r shif t signa l produce db y a movin g particle , thi s measure dvelocit y i s essentiall y the particl e velocit y rather tha n fluid velocity . A s aresult , Buchhav e e t al . (1979 ) suggeste dacriterio n fo r particl e selectio n fo r

fluid measurement . Empirically , seedin g particle s wit h ligh t density shoul db e chose n les s tha n 1 7 ur n fo r measurin g ai r

velocit y an d4 9 ur

n fo r wate r flui dassessment . Consequently , whe n thes e particle s ar

e use da s the seedin g particles , th e velocitie s measure db y LD A wil l b e regarde da s th e fluidvelocity . Thus , avelocit y measure db y LD A i s considere da s particl e velocit y o r flui d velocit y dependin g o n the Stoke s Numbe r o f the seedin g particles . 3.1.2 Literature

view of LDA applications

in gas-solid

flow Gas-soli dflow lik e pneumaticall y conveye dbul k solid s i s frequentl y met i n man y industria l fields. Instrumentatio n fo r detaile dgas-soli dflo w measurement s i s highl y desirabl e i n orde r t o understan dphysica l phenomen aan dmechanism s fo r optimu mdesig n an doperatio n o f gas-soli d systems . Sinc e i t

i s anon-intrusiv e an dhighl y accurate velocit y measurement instrument , LD A ha s bee n widel y applie dt o investigat e characteristic s o f gas-soli dflow individuall y o r combine d wit h other

instruments . A s aresult , there ar e numerou s paper s i n whic h som e interestin g result s hav e been publishe dan dsome valuabl e technique s use dfo r extendin g th e function s o f LD A hav e bee n reporte das well . Sinc e the ke y functio n o f LD A lie s i n velocit y measurement , paper s relate dt o th e velocit y measuremen

t o f asingl e phas e i n gas-soli dflow ar e liste di n Tabl e 3 . Fro mthe 1970s , th e velocit y profile s o f

asingl e phas e i n gas-soli dflo w i n vertica l o r horizonta l pipe s (channels ) an d Circulatin g Fluidize dBe dhav e bee n measure dalon g apip e radiu s o r an y specifi c lin e b y usin g LDA . Th e effec t

o f characteristic s suc h as particl e velocity , the roughnes s effec t o n th e development

o f astabilize dlamina r

boundary layer , th e effec t o f inter-particl e collision s an dth e

2 9



## VES01706 4A n investigatio n o f particl e dynamic

s in a dilut

e phas e pneumati

c conveying syste

m effec t o f particle-wal l collision s hav e bee n completel y or partiall y explore dthroug h analyzin g the velocit y dat ameasure db y LDA . I n addition , severa l paper s als o use dLD A t o calibrat e other instrument s lik e Electrica l Capacitanc e Tomograph y (ECT ) fo r velocit y measurement . Sinc e the velocit y o f

asingl e phas e i s jus t

on e o f th e basi c parameter s t o characteriz e gas-soli d flow , i t i s mos t interestin g t

o obtai n th e othe

r possibl e parameter s suc h a s soli dconcentratio n an d particl e siz e as wel l as thei r distributio n o n across-sectio n o r alon g th e flui ddirection . T o full y characteriz e unsteady gas-soli dflow, i t i s importan t

t o measure particl e velocit y an dother parameter s simultaneously . Tabl e 3. 2 list s the previou s paper s i n whic h LD A wa s combine dwit h othe r instrument s lik e apyromete r an dalaser-particle-sizin g syste mt o obtai n additiona l informatio n lik e particl e temperature an dparticl e siz e a s wel l a s measurin g particl e velocity . Moreover , ther

e hav e bee n extensiv e studie s fo r extendin g th e standardsingl e poin t velocit y measurement

o f LD A t o multifunctiona l operation , whic h includ e multi-poin t LDA , simultaneou s tw o phas e velocit y measurement an dparticl e siz e measurement b y usin g a

n individua l LD A device . Fo r

example , severa l paper s describ e asimila r nove l metho do f

settin g tw o threshol d amplitud e value s t o classif y Dopple r

signal s fo r

measurin g velocitie s o f tw o phase s a

t the same time . Th e principl e o f

thi s metho di s base do n th e fac t tha t ligh t scattere db y alarg e particl e ha s a larg e pedestal amplitud e o f Dopple r signal . Additionally , severa l numerica l paper s demonstrat e ho w t o asses s the stabilit y o f signa l processin g i n LD A an danalyz e th e possibl e error s o f LD A usin g adigita l metho dt o measur e the frequenc y o f

Dopple r

signals . Tabl e 3. 3 list s the correspondin g principl e an dthe brie f result s o f

thes e paper s fro mth e 1980s . Wit h regar dt o th e optica l arrangement s i n the experiment s listed , thre e general type s ca n b e categorize das : i n an ope n environment ; i n abounde dregio n wit h aslo t o r hol e a s the measurement

window ; an di n atransparent bounde dregio n withou t the additiona l flat

windo w o n the wall . Obviously , n o ligh t refractiv e effec t

occur s i n an ope n environmen t an dthere i s onl y a ligh t shif t phenomeno n o n aflat window . Bu t

i t i s necessary t o conside r the refractiv e effec t whic h result s i n changin g the directio n o f alase r beama t acurve dsurface . A s fo r th e refractiv e effect , Tsuj i e t

al . (1982 , 1984 ) mentione di t i n hi s horizonta l an dvertica l pip e flow measurements . Bu t

n o detaile dinformatio n wa s give n fo r analyzin g th e deviatio n o f the LD A measurin g poin t

fro mit s expecte dpositio n i n pipes . I t wa s assume dtha

t the influenc e o f refractio n coul db e neglecte ds o lon g a s the traversin g o f the measurement

poin t wa s withi n a specifi c rang e i n apipe . Mos t paper s giv e n o clear

informatio n o n dealin g wit h th e refractio n effect . Man y experiment s i n pipe s o r channel s wer e carrie dou t t o measure particl e velocit y alon g apip e diamete r

lin e rather

tha n o n awhol e cross-section . Thus , i t i s abasi c an dessentia l tas k t o stud y the refractiv e effec t

due t o pip e curvatur e fo r measurin g particl e velocit y i n gas-soli dpip e

3 0



## VES01706 5Chapte r3 Extendin

g LD A fo rparticl e flo w measuremen

ti n pipe s flow.
I n the previou s sectio n (3.1.1) , w e hav e discusse dthe fac t tha t dat arecorde db y LD A represent the velocit y o f

aparticl e passin g throug h the measurement volume . Wit h regardt o gas-soli d measurement , particle s o f soli dphas e ar

e directl y regarde da s the seedin g particles . Consequently , the measure dresult s ar e normall y considere das agroup o f instantaneou s particl e velocitie s withi n aspecifi c interval . Th e loca l velocit y o f the soli dphas e a

t thi s measurement

poin t i s usuall y average dfro mthi s tim e serie s data . However , particl e siz e o f th e soli dphas e may b e distribute dwidel y an dparticl e densit y may als o diffe r fo r multi-materia l soli dphase s suc h as pneumaticall y conveyin g afue l mixtur e o f pulverise dcoa l an dbiomas s particles , l n thes e cases , the accurate time-average dvalue wil l b e strongl y dependen t o n obtainin g enoug h sampl e dat ai n th e recorde ddat ase

t o f particl e velocity . I n particular , particl e velocit y varie s wit h its Stoke s Numbe r whic h i s relate dt

o particl e size , particl e densit y an dloca l ai r

velocit y a

t asampl e point . Hence , considerin g the prope r sampl e rate o f

LD A i s als o essentia l an dnecessar y t o gas-soli d pip e flow measurement . Fo r the abov e discusse dreasons , w e wil l study th e refractio n effec t an dsampl e rat

e i n the nex t tw o sections .

3 1



## VES01706 6A n investigatio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m

Tabl e 3
. 1 Th e application s o f an individua l LD A (Singl e phas e measurement) Referenc e Experimenta l rig Flo w conditio

n Measuremen t windo w typ e Result s Birchenoug

h an d Maso n (1976 ) Barren te t al . (1995 ) 3 m long , <|>49.4m m vertica

l glas s tub e

A n 800m m wid e an d 1100m m lon g fla tplat e wit h a n elliptica

l leadin g edg e sectio n an d porou s suctio n surfac e mounte d i n th e centr e of win d tunne l (800m m width , 600m m height,1600m

m length ) A je t(it s centra l ij)40m m an d it s annula r (j)68mm

) wa s mounte d int o a <|>2000m

m cylindrica

l containe r A n in-lin e tub e ban k consistin

g of a 6* 6 arra y of carbo n stee l tub e wa s arrange d i n a win d tunne l <f- Th e rig i s sam e a s th e abov e on e fo rmeasurin

g th e instantaneou

s inciden t an d reboun d particl e velocitie s b y usin g tw o dimensiona

l LD A i n th e immediat e vicinit y o f th e tube s surface . Parkhomo

v A 2500m

m lon g vertica l Fa n e tal . (1996 )

Tu e tal . (1997 )

Mors i e tal . (2004 ) Ai rconveyin g velocity

, 16 - 48m/ s -v * Soli d loadin g rati o les s tha n 2. 2 -v - Alumin

a powde r wit h mea n siz e 21p m

-v " Ai rvelocit

y les s tha n 10 5 m/ s •v - Seve n kind s o f particle s rangin g fro m 0. 5 t o 1.5m m Primar y ai rvelocit y 20m/s ; Secondar y ai rvelocit y rangin g fro m 3 0 t o 6 0 m/ s Soli d loadin g ratio , 0.5-1. 5 Silic a ge l powde r (it s mea n siz e 5 0 an d 20 0 pm ) 11.2m/ s ai rconveyin

g velocit y •s > tw o kind s of glas s bead s (6 6 an d 9 5 pm ) *v - soli d loadin g rati o 0 . lkg/k g < • Ai rvelocit

y (8~13.7m/s

) -v " Glas s bead s (mean s siz e 35,6 6 an d 9 3 pm ) *v - Soli d loadin g O.lkg/k g Direc

tmeasuremen

t withou tconsiderin

g th e effec to f ligh trefractio

n o n th e tub e surfac e

N o informatio

n abou t arrangin g th e measuremen

twindo w

Fla tglas s measuremen

t windo w o n th e wal l o f th e containe

r
A glas s measuremen

t windo w of 360*500mm 2wa s ope n o n th e ban k wall. No informatio

n abou t arrangin g th e measuremen

twindo w

Reynold s numbe r 1530 0 N

o mentio n -v

- Wit h increasin

g soli d loading , th e experimenta

l result s displa y tha tth e particl e velocit y profile s becom e flattened Ther e i s negativ e particl e sli p a tth e pip e wall. •4 - Examinin

g th e effec tof isolate d surfac e roughnes

s element s o n th e developmen

to f stabilize d lamina r boundar y layer s b y three - componen

tLDA . "v " Th e critica l spee d a twhic h disturbance

s ar e propagate d downstrea

m fro m a surfac

e ha s bee n foun d t o b e characterize

d b y a constan

tvalu e o f roughnes s Reynold

s numbe r (abou t800) . Th e result s indicat e tha tth e diffusio n o f th e particl e phas e i n th e radia l directio n i s muc h slowe r tha n tha tofthe ga

s phas e an d th e mea n velocit y profile s o f th e particl e phas e ar e flatter tha n thos e o f th e ga s phase . Th e collision

s betwee n particle

s an d th e tub e surfac e ha d considerabl

y influenc

e o n particl e motion , whic h resulte d i n substantia

l difference

s i n th e flo w pattern

s betwee n tw o phase s throug h th e tubes . -y " Fo ra singl e tube , th e particl e reboundin

g flo w patter n i n th e vicinit y o f th e wal l wa s mainl y affecte d b y particl e inerti a (Stoke s Number). Th

e ga s flow a thig h Reynold

s numbe r wa s foun d t o suppres s th e reboun d tendenc

y ofthe particles

. •v- Fo rtub e bundl e structure

, particle s reboundin

g fro m th e approachin

g tube s upstrea m migrate

d downstrea

m an d impinge

d th e tube s i n a n extremel y comple x an d rando m disposition

. A significan

tanisotrop

y o f fluctuation

s o f particl e 3 2



## VES01706 7Chapte r 3 Extendin

g LDA fo r particl e flow measuremen

ti n pipe s
(2007 ) stainles

s stee l pip e wit h 446m m
Datt a et . al. , A 7 m lon

g horizonta

l pip e (2007 ) sectio

n (<|)57mm

) an d a 3 m lon g vertica l section . •v

- Glas s bead s (mea n siz e 50pm ) -v - Trace rparticle s 2~3p m Ai rvelocit

y rangin g fro m 1. 0 t o 5.0m/ s Polyamid e chip s approximat

e (3m m long , 3 m m wid e an d 1m m thick ) No mentio n velocit y ha s bee n found . Th e amplitud

e of turbulen tfluctuation

s o f particl e velocit y i n th e axia l directio n i s muc h highe r tha n tha ti n th e radia l directio n Fo rlo w soli d concentration

, th e pixe l value s ofth e image s measure

d b y EC T wer

e lo w a s well , ther

e wa s no tadequat

e signa l t o obtai n vali d velocit y measuremen

tfrom th

e instantaneou

s correlatio

n function . Thi s wa s observe d fro m th e velocit y distributio

n profil e obtaine d b y EC T compare

d wit h th e dat a o f LD A
Tabl e 3. 2 The application

s o f LD A combine

d wit h othe r instrument

s fo r gas-soli

d flow measurement

s Referenc e Experimenta l rig Flo

w conditio

n Additiona

l instrumen

tan d Measuremen

twindo w typ e Result s Finck e e tal . Powder

s o f a meta l (Ni-Al ) Ai rspra y velocit y A two-colo r pyromete

r Measure

d particl e size , velocit y an d temperatur

e (1990 ) an

d a meta l oxid e (AI2O3 ) 100~300m/ s fo

r measurin

g particl e simultaneousl

y wer e presente d fo r Particl

e siz e withi n temperatur

e Th

e particl e velocitie

s an d temperatur

e wer e studyin g th e plasm a spray - 5-10

0 p m A scattered-ligh t insensitiv e t o th e particl e injectio n rat e ove r th e coatin g proces s Particl e mas s flow rat e particl

e siz e loadin g range . withi n 0.2 5 t o 5 measuremen t Particl e injectio n geometr

y an d particl e velocit y an d kg/hou r N o measuremen

t mas

s significantl

y affec tth e spatia l distributio

n o f windo w (i n ope

n particl

e siz e i n th e plasm a plum e an d thu s ca n alte r th e environment

) characteristic s of th e deposite

d coating . Hube r an d I

n a dilut e pneumati

c Ai rconveyin g velocit y Phas

e Dopple r Th

e experimenta

l result s indicate d tha tth e pip e wall Sommerfel

d conveyin

g system , th e rangin

g fro m 1 0 t o Anemometr y (PDA) roughnes s ha d a considerabl

e influenc

e o n th e particl e (1994 ) measurement s wer e 30m/

s fo r particl e siz e motio

n afte r a wal l collisio n and , especiall y fo r smal l performe d i n horizonta

l Soli

d loadin g rati o measuremen t collisio n angles . an d vertica l pipe s betwee n 0. 2 an d 1. 0 Laser-ligh

tshee t A n increase d conveyin

g velocit y reduce d segregatio

n vertica kg/k g techniqu e fo r i

n a horizonta

l pip e du e t o th e highe r flow turbulenc

e Glas s bead s wit h mea n measurin

g th e soli d established

. diamete r 40p m concentratio n withi n Th

e motio n o f larg e particle s (large r tha n 100pm ) wa s th e whol e pip e cross - strongl

y governe

d b y inertia l effect s an d n o marke d sectio n segregatio n wa s observe d i n th e differen tpip e N o informatio

n abou t element

s considered

. th e ligh trefractiv

e effec to n pip e surfac e 3 3



## VES01706 8A n investigatio n o f particl e dynamic

s in a dilat

e phas e pneumati

c conveyin

g syste m

Va n d e wal l an d So o (1994 ) A cyclone-standpip e recirculatin

g pip e flo w syste m A horizonta

l pip e (|>127m m Ai rconveyin

g velocit y 20m/ s < - Glas s bead s <|>44-62u

m < • Soli d loadin g rati o 0.4-2. 2 kg/k g -v

* Phas e Dopple r Particl e Analyze r (PDP A o r PDA ) N o informatio

n abou t th e effec to f th e ligh t refractio n o n th e pip e surfac e -0- Determinatio n o f instantaneou

s loca l particl e velocit y an d densit y Th e experimenta

l dat a confirme

d tha tPDP A provide

s a mean s o f determinin

g th e instantaneou

s loca l particl e densit y whe n th e averagin

g procedur

e satisfie d th e criterio n o f continuu m counterpar

tof time-averagin

g an d lengt h scal e relation . Th e loca l averagin

g tim e shoul d includ e o n th e orde r of 10 2 particle s forth e continuu

m approximatio

n an d th e pat h lengt h shoul d b e smalle r tha n th e characteristi

c dimensio

n of th e physica l syste m Ba o an d So o (1995 ) Th

e sam e a s th e abov e ri g Ai rconveyin

g velocit y 2 0 m/ s Soli d loadin g rati o 1.92,2.0 4 an d 2. 5 kg/k g Glas s bead s rangin g fro m 0~80p m wit h th e mea n siz e 4 5 p m PDP

A <* • N o detai l informatio

n abou tth e effec to f refractio n a tth e pip e wal l Use d a two-dimensiona

l Lase r Dopple r Velocimete

r combine d wit h a phas e Dopple r particl e analyze

r t o determin e averag

e an d fluctuatin

g propertie

s an d Reynold s stresses . Th e travers e of th e measurin

g volum e alon g a vertica

l diamete r gav e result s showin g th e gravit y effec ti n th e flow of a gas-particl

e suspensio

n Th e instantaneou

s loca l particl e clou d densit y an d velocit y showe d th e natur e o f distributio

n i n th e particl e phase .

Tabl e 3. 3 Developmen

to f LD A multifunctio

n forgas-soli

d flow measuremen

t Referenc e Researc

h Objective

s an d Experimenta

l ri g Flo

w conditio

n Multifunctio n principl

e an d Measuremen

twindo w Result s Tsuji e tal . A horizonta

l glas s pip e (1982 ) (<|)30.5mm

) i n a pneumati

c conveyin g syste m Ai rconveyin g velocit y fro m 6 t o 20m/ s Tw o kind s o f plasti c particle s (100 0 kg/m

3 ) wit h 0. 2 an d 3.4m m mea n siz e respectivel

y Solid loadin

g rati o les s tha n 6 kg/kg

. Ammoniu

m chlorid

e Principle : determinin g th e pedesta l componen

t o f th e burs tsigna l o f LDA , th e large r a particl

e is, th e large r th e pedesta l componen

tis . Window: considerin

g th e refractiv e effec ta tth e pip e wall, bu twithou t Measure

d th e velocitie

s o f ai rphas e an d particle s simultaneousl

y A s th e loadin g rati o increase

d an d th e ai rvelocit y decreased

, mean-velocit

y distribution

s of bot h phase s becam e mor e asymmetrica

l tendency

. Th e effect s o f th e soli d particle s o n air-flo w turbulenc e varie d greatl y wit h particl e size . Tha tis, 3.4m m particle

s increase d th e turbulenc

e markedly

, whil e 0.2m m one s reduce d it . 3 4



## VES01706 9Chapte r 3 Extendin

g LDA fo r particl e flow measuremen

ti n pipe s

Tsuj i e tal . (1984 )

Dupon te tal . (1991 )

Cha o e tal . (1992 ) A vertica

l glas s pip e (<t>30.5mm

) i n a pneumati

c conveyin g syste m

A circula r cylinde r i n a win d tunne l fo r studyin g th e wak e developin

g behin d i t

Th e experiment

s wer e performe d i n th e shea r laye r o f turbulen tje tflow issue d fro m a larg e 10 0 an d 1 0 m m nozzl e

Grechikhi n Numerica

l simulatio

n o f an d analyzin

g th e error s o f th e Rinkevichyu

s signa l processo r o f a LD A (1993 ) usin

g digita l method s t o measur e th e frequenc

y o f th e Dopple r signal . •0-

•0- (<j>0.6pm

) a s tracer s Ai rconveyin

g velocit y fro m 8 t o 20m/ s Fiv e kind s of glas s bead s (mea n siz e 3.43,2.78,1.0, 0. 5 an d 0. 2 mm ) Soli d loadin g rati o les s tha n 5 kg/kg

.

Ai rvelocit

y 4. 5 an d 6 1 m/ s N o informatio

n fo r tracer s

Seedin g particle s of paraffi n oi l wit h a nomina

l diamete r of lp m Ai rvelocit

y 4m/ s fo r th e smal l nozzl e an d 1.8m/ s for th e larg e nozzl e an

y detaile d explanation

. Th e sam e a s th e abov e

Use d spectra l analysi s metho d t o asses s th e sampl e dat a obtaine d b y LD A Window: i

n ope n environmen

t

Use d a n unequall

y space d fracta l interpolatio

n metho d t o reconstruc

tth e random , intermittent

, lo w dat a rat e LD A signal

s fo r spectra l analysi s Window : i n ope n environmen

t Considere

d th e photodetecto

r outpu trepresente

d a s th e su m o f particl e velocit y signa l an d nois e componen

tof a stead y Gaussia n proces s wit h zer o averag e valu e Th e error s relate d t o th e frequenc

y differenc

e of th e interferin g beams , th e perio d o f th e interferenc

e patter n an d th e effectiv e radiu s o f th e measurin

g regio n *v

- Th e smalle r th e particl e size , th e flatter wa

s th e mea n ai r velocit y profil e fo r th e sam e mas s flo w rati o o f solid s t o air . Larg e particle s increase

d ai r turbulenc e throughou

tth e pip e section , whil e th e smal l particle s reduce d it . •v - Bot h effect s o f promotio

n an d suppressio

n o f turbulenc e wer e observe d a tth e sam e tim e i n th e presenc e of particle s o f mediu m size , tha tis , th e turbulenc e wa s increase d aroun d th e pip e centr e an d reduce d nea r th e wall. •v " A simpl

e mode l o f PSD (powe

r spectra l density ) wa s introduce

d t o determin

e whethe r th e particle

s use d fo r fh e seedin g wer e abl e t o follo w th e characteristi

c frequencie

s o f th e flow -4 * I tha s bee n show n tha tth e PSD ca n b e relie d o n u p t o frequencie

s muc h greate r tha n th e mea n samplin

g rat e a s lon g a s ther e ar e wel l pronounce

d peak s i n th e spectrum

. •v " Th e reconstructe

d resul tno tonl y augmente

d th e dat a point s t o improv e th e statistic s bu tals o retaine d th e turbulen

tfracta l dimensio

n ofthe flow. -v " Th e result s showe d tha tth e fracta l reconstructio

n metho d coul d properl y restor e th e characteristic

s of pea k frequencie

s of th e flo w fro m lo w dat a rat e LD A signal

s o r from decimate

d data , whil e th e conventiona

l sample-and-hol

d metho d faile d t o captur e an y o f th e majo r pea k frequencies

. - V sDevelope

d a metho

d for evaluatin

g th e perio d o f th e high-frequenc

y filling of

th e LD A signa

l fro m th e coordinate

s of th e "zero" o

f th e proces s an d fo r estimatin g th e signa l frequenc

y fro m th e positio n of th e maximu

m valu e o f th e spectra l density . Th e result s reporte d sho w tha tth e limitin g value s o f th e tota l erro r o f measuremen

tof th e LD A signa

l 3 5



## VES01707 0A n investigatio n o f particl e dynamic

s in a dilut

e phas e pneumati

c conveyin

g syste m

Che n an d Kadamb i (1995 )

Fran k e tal . (1996 )

Werthe r e tal. (1996 ) A 3.05

m lon g PV C pip

e (<|)25.4mm

) connecte

d wit h a glas s tes tsectio n

A horizonta

l an d vertica l glas s pip e i n a hea ttransfe r statio n

A col d mode l of Circulatin

g Fluid Be

d (CFB ) wit

h inne r diamete r o f th e rise r 0.4 m an d 15.6 m height . Th e measuremen

tregio n locate d a ta heigh tof 6 m abov e th e distributo

r 4

- Silic

a ge l particle s o f mea n siz e 40p m 50 % sodiu m iodid e solutio n a s th e liqui d phas e whos e refractiv

e inde x i s simila r t o th e silic a particle s

Use d th e dimensionles

s parameter

s withou tclea r dat a abou tfluid condition s

Superficia

l ga s velocit y 4m/ s Quart z san d wit h mea n siz e 166p m Solid s volum e concentratio

n 1.2 % •v

* Use d th e matche d refractiv e inde x o f th e soli d an d liqui d t o discriminat

e th e signa l amplitud e accordin

g t o th e histogram

s of measure d velocit y dat a "v - Withou

tconsideratio

n o f th e refractio

n effec to n th e pip e wal l Velocity-are

a method s ar e characterize

d b y dividin g th e cross-sectio

n int o a numbe

r o f annul i of equa l area . Withou tinfonnatio

n abou teffec tof ligh t refractio n o n th e pip e wal l

Th e LD A prob

e wa s containe d i n a miniaturize

d measurin

g hea d whic h coul d b e inserte d int o th e CF B Compare d wit h dat a measure d b y fibre-optica

l prob e Window: n

o refractio

n effec tdu e t o th e Prob e bein g inserte d int o th e CF B frequenc y ca n b e decrease

d t o 0.1-0.3% . Discriminate

d betwee n soli d an d liqui d velocitie

s i n a refractiv

e inde x matche d solid-liqui

d slurr y flo w b y identifyin

g th e histogra

m peak s associate

d wit h th e soli d an d liqui d velocitie

s respectively

, •v - Th e experimenta

l dat a demonstrate

s tha tthi s discriminatio

n techniqu

e i s suitabl e t o b e applie d t o slurr y flow s flo w o f lo w turbulenc

e intensit y (les s tha n 10% ) wit h volumetri

c concentratio

n a s hig h a s 25 % i n th e heterogeneou

s an d saltatio n flo w regime s «v - Develope

d a multi-poin

ttechniqu

e o f LD A fo r flo w rat e measuremen

ti n asymmetri

c an d unstead y pipe flow Th e uncertaint

y o f flow-rat e measuremen

twa s decrease d les s tha n 1 % b y usin g velocity-are

a methods . Th e minimu m numbe

r o f radi i fo r slightl y asymmetri

c flow i s four , otherwis e si x o r eigh tradii ar e use d •v - Th e desig n o f miniaturize

d low-cos

tmulti-poin

t sensor s wit h jus ton e lase r an d signa l processo

r i s show n t o b e possible

. •v " Th e experimenta

l dat a confirme

d tha tth e LD A techniqu e i s a reliabl

e an d precis e too l fo r particl e velocit y measurement

s i n a CF B "v - I tals o demonstrate

d tha tth e result s of bot h LD A an d th e Fibre-optica

l prob e yieldin g i n th e CF B rise

r wer e i n clos e agreemen

t

Mathiese n e tA clea

r PV C riser •f rAi rsuperficia

l velocitie

s -f rTh e Shap e -v

- Develope

d a modifie

d Shap e Discriminatio

n 3 6



## VES01707 1Chapte r 3 Extendin

g LD A fo r particl e flow measuremen

ti n pipe s

al . (1999 ) Oj.50.8mm

, 2.7 5 height ) i n a CF B wa

s use d an d th e tes tsectio n wa s locate d 1.12 m ove r th e elbo w inle t 0.

7 an d 1.4m/ s FC C catalys

twit h densit y 170 0 kg/m

3 an d siz e rang e fro m 1 1 t o 18 0 p m (Saute r mea n diamete

r 55pm ) -v - Solid concentratio

n i n CF B 0. 5 an d 2 % Discriminatio n techniqu

e base d o n knowledg

e abou tDopple r burs t signa l wa s use d t o determin e particl e siz e throug h processin

g th e Dopple r signal . A pai r o f flatglas s measuremen

twindow s wer e mounte d o n th e wal l Techniqu e t o exten d th e LD A techniqu

e t o measur e particl e siz e directl y Th e experimenta

l result s showe d tha tther e wa s n o significan tagglomeratio

n i n th e gas-soli

d flo w system . Typica l annulus-cor

e flow behavio

r wa s observe d Th e larges tparticle s showe d th e highes tfluctuatin

g velocity . Thi s behavio

r wa s cause d b y significan

t gas-soli d interactions

.
Hussaino v e t a l (2000 )

Har tet . al . (2001 )

Lai n e tal . (2002 ) A vertica

l two-phas

e windchanne l wit h a close d tes t section . Th e tes tsectio n wa s mad e o f plexiglas s abou t2 m length . It s initia l uppe r cros s sectio n 200x20 0 mm

2an d it s downstrea m cross-sectio

n wa s 205x20 5 mm

2 Develope d a seedles

s equivalen to f LD A fo rus e i n low-turbulenc

e o r supersoni c flows o r elsewher e wher e seedin g i s undesirabl

e o rimpractica

l A horizonta

l channe l o f 6 m lengt h wit h th e sectio n 35x350mm 2 0- Ai rconveyin g velocit y -v * 9.5/ s Glas s bead s wit h mea n siz e 700p m Soli d loadin g rati o les s tha n 0. 1 kg/k g Ti0 2particle

s (2pm ) a s tracer s Use d tw o lase r power s o f 2 6 an d 1 0 m w t o for m tw o channel s fo r measurin g ga s (tracers ) an d particl e phas e (glas s beads ) velocitie

s simultaneousl

y Fla tmeasuremen

t windo w Th e principl e o f Heterodyn

e Non-resonan

tLaser-induce

d Therma l Acoustic

s (LITA) i

s t o analyz e th e Dopple r shift s ofth e acousti

c wave s produce

d b y a shor tpuls e pumpe d lase r i n th e mediu m fo rmeasurin

g temperatur

e an d velocity . Neithe r molecula

r no rparticulat

e see d i s adde d t o th e flow . Ai rvolum

e flow rat

e fro m 50 7 t o 100 2 m

3 / h an d maximu m ai rconveyin

g velocit y 30m/ s Solid loadin

g rati o u p t o 2 kg/k g Fiv e kind s o f glas s bead s wit h mea n siz e 60,100, 195 , 62 5 an d 100p m respectively

. Measure d tw o phas e velocitie s simultaneousl

y base d o n th e signa l phas e discrimination

, whic h wa s introduce

d i n th e pape r ofQi u etal . (1991

) A glas s plat e o f measuremen

twindo w 3 5 b y 35 0 m m wa s inserte d a tth e to p wall . •v

* Th e coars e particle s considered

, attenuate

d th e grid generate d turbulenc

e resultin g i n a n increas e ofth e turbulen tenerg y i n th e sub-rang

e o f th e energ y containin g eddies . • Y * Th e influenc

e ofthe Stoke

s numbe r o n th e turbulenc e modulatio

n o f th e carrie r flow i s strong .

"v - A compact

, portable , single-componen

theterodyn

e LIT A Velocimete

r wa s constructed

. •4

- A compariso

n ofthe experimenta

l dat a wit h Pitotstati c prob e measurement

s showe d tha tthe y agree d wit h eac h other . Repeate d measuremen

to f variou s flow profile

s showe d excellen

tstability . -y - Th e experimenta

l dat a validate d th e Reynold

s stres s turbulenc e mode l i n conjunctio

n wit h a wal l roughnes s mode l an d a stochasti

c inter-particl

e model , whic h wer e introduce

d b y thi s author . -y " I tals o demonstrate

d tha tbot h inter-particl

e collision s an d wal l roughnes

s ha d a ver y stron g effec to n th e developmen

to f th e particl e phas e properties

. A sligh tenhancemen

tof th e turbulen

tkineti c energ y wa s cause d b y particl e collision

s 3

7



## VES01707 2A n investigatio n o f particl e dynamic

s in a dilut

e phas e pneumati

c conveyin

g syste m

•v - Spherica

l trace r particle s wit h a nomina

l siz e 4p m Furunic h e tA developmen

to f a two - A two-dimensiona l flo w al . (2002 ) componen

tvelocit y channe

l of 16 0 b y 160m m profile r usin g a fibe r multi- wa

s use d t o simulat e poin tLD A an d a CC D are

a 0.065m/

s wate r flo w imag e senso r "5

* Trace rparticle s o f glas s bead s wit h 100p m mea n size . Combine d th e multipoin tLD A syste

m an d a CC D are a imag e senso r t o measur e a twocomponen

tvelocit y profil e simultaneousl

y a s a functio n o f tim e •v

- A nove

l metho d t o measur

e a two-componen

t velocit y profil e simultaneousl

y wa s develope

d b y usin g combine

d syste m o f th e CC D are

a imag e senso r an d th e multi-poin

tLDA .
Fitzpatric k an d Simo n (2005 ) A n isotherma l je ta ta Mac h numbe r o f 0.7 5 Measure d th e velocitie

s nea r th e en d o f th e potentia l cor e o f th e je t • Ai rvelocit

y 0.7 5 Mac h N o detai l o n trace r particle s Use d th e sample-and

hol d reconstructio

n techniqu e fo r determinin

g th e cros s powe r spectr a of turbulenc e -v - Th e result s obtaine d b y th e propose d metho d wer e muc h bette r tha n th e mea n sampl e frequenc

y fo r th e lo w LD A dat

a rate s an d t o th e mea n sampl e frequenc y fo r th e highe r rates . Th e computationa

l tim e require

d fo r th e ne w approac h i s significantl

y les s tha n fo r th e traditiona

l slo tcorrelatio

n metho d i n LD A signa

l processin

g L i e tal . A developmen to f multi - (2005 ) poin

tLD A 4- B y employin g tw o acousti c opti c modulator

s fo r bot h bea m splittin g an d frequenc

y shifting

, a multipl

e measurin

g volume s coul d b e forme d b y intersectin

g th e multipl e diffractio n order s generate

d b y th e tw o modulators

. Eac h measurin g volum e ha d it s frequenc

y shift , whic h wa s proportiona

l t o th e correspondin

g velocit y a tth e loca l poin t -v - I n contras tt o th e othe r multi-detecto

r system , th e structur e ofthi s multi-poin

tLD A syste

m wa s significantl

y simplified. A s th e multi-channe

l informatio

n wa s demultiplexe

d b y a single-channe

l signa l processor

, th e processin

g spee d neede d t o b e increased

.

3 8



## VES01707 3Chapte r 3 Intendin g LD A fo rparticl e Ho w measurementi n pipe s 3.2 . EXPERIMENTA L APPARATU S

•-f- i M ; rou t

Notic e

— H (1 ) Cyclon e i2 ) i>crev°/Feede r ii) Centrifuga

l Fi n

Figur e 3. 2 Sketc h ofth e experimenta

l rig I n order t o characteriz e th

e cross-sectiona l characteristic s o f th e soli dphas e i n differen t pip e element s o f

adilut e pneumati c conveyin g systems , apilo t scal e positiv e pressur e dilut e pneumati c conveyin g syste mwas buil t whic h involve dhorizonta l an dvertica l pipe s connecte db y a n elbo w (R/D=1.3) . Th e schemati c diagramofth e experimental apparatu s i s show n i n Figur e 3.2 . Th e pip e inner

diameter an doute r diamete r

ar e d>7 5 and<j)85m

mrespectively . Th e effectiv e lengt h o f the horizonta l glas s pipe s i s 4 mandthe vertica l i s 2 mlong . A T-piec e i s use dt o connec t

a screw-feede r

wit h the horizonta l pip e an dseveral plasti c tube s ar e use dt o connec t

acentrifuga l fa n andacyclone . Thi s cyclon e i s use dt o separat e particle s fro mth

e ai r a t th e en do f th e system . The n particle s separate dfro mai r ar e collecte di n astorag e reservoi r fo r recyclin g i n furthe r experiments . Additionally , ever y metal connecto r

betwee n the pipe s i s earthe dt o reduc e electrostati c ris k

due t o particle-wal l collisions . Ai r flo w i s provide db y acentrifuga l fa n wit h amaximu m0.0 5 m 3 / s volum e flowrat e unde r agains t a2.2kP aback-pressure . Ai r conveyin g velocit y ca n var y fro m1 0 t

o 42m/ s b y adjustin g th e pip e back-pressure an dth e butterfl y valve a

t the inle t o f th e fan . Th e maximu mparticl e mas s flo w rat e o f the feede r

wa s experimentall y determine dt o b e 1.0x10" ' kg/ s fo r

glas s bead s with actual density 255 0 kg/m 3 an dbul k density 155 9 kg/m 3 .

3 9



## VES01707 4A n mvcMig;tlic)i i o f p;irlicl c dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m
Accordin g t

o th e numerica l result s o f Chapte r 2 , whic h state s tha

t particle s wit h differen t material s i

n gas-soli dpip e flo w hav e simila r propertie s a

t equa l Stoke s Numbe r

(St) , thre e type s o f glas s bead s an dasmok e ar e selecte di n our

experiment . Glas s bead s were use dt o simulat e gas-soli dpip e flo w an dth e smoke wa s use da

s the seedin g particl e fo r ai r flui dvelocit y measurement . Th e manufacturer' s dat a(Wor f Glaskugeln , 2008 ) indicat e tha t the first typ e o f glas s bead s rang e fro m0 t o 50pm , the secon dwithi n 70-110p man dth e thir dvarie dfro m 180-300 um . Sinc e the pipelin e i s mad e o f glass , th e ri g ca n be use dt

o investigat e propertie s o f gas-soli dflo w i n ahorizonta l an dvertica l pip e as wel l a s i n a n elbo w b y usin g LD A or an y othe r optica l imagin g system . 3.3 DEVELOPIN G TH E SPATIA L TRANSFOR M MATRI X FO R LD A PIP E FLO W MEASUREMEN T Th e revie w o f

LD A application s i n gas-soli dflo w discusse di n the sectio n o f 3.1. 2 indicate s tha

t fe w paper s discus s th

e refraction effec t

whic h cause s th

e measurement

volum e o f

LD A t o deviate fro mit s expecte dpositio n i n the pip e whe n th e crossin g poin t

o f th e lase r beams passe s throug h the curve dsurfac e o f

the pipe . In order

t o acces s the whol e are ao f apip e cros s section , i t

woul d bette r t o evaluate theoreticall y thi s deviation . Consequently , ashif t coordinat e matri x wa s devise dt

o ma p actual position s o f

the measuremen

t volum e i n the pipe . Thi s i s calle dth e transfor mmatrix . I n thi s section , the basi c parameter s o f LD A use di n thi s study ar e introduced . The n w e wil l demonstrat

e ho w t o calculat e aspatia l coordinat e matri x fo r agive n experimental ri g an dafixe d optica l arrangemen

t o f the LDA . 3.3.1 Parameters

ofthe LDA system Tw o FibreFlo w probe s wit h afron t len s o f f=800m mar

e use dt o measur

e three dimensiona l velocit y i n a3 D Dante c LD A system . On e prob e combine s tw o pair s o f beam s wit h wavelength s o f 48 8 nm(blue ) an d514. 5 n m(green ) respectively . Th e plane s produce db y the differen t coloure dbeam s ar

e perpendicular

t o eac h other . Anothe r prob e wa s integrate dwith one pai r o f 476.5n mbeam s (violet) . A s aresult , the 3 D particl e velocit y coul dbe measure dsimultaneousl y b y usin g thes e tw o probe s when three pair s o f beam s focu s o n th e sam e point . A 40 M shiftin g H z frequenc y o f

aBrag g cel l i s selecte dt o detennin e the particl e velocit y direction . Tabl e 3. 4 list s th e essential parameter s o f thi s three-component

LDA .

4 0Chapter 3 Intendin g LD A fo rparticl e flo w measuremen ti n pipe s Tabl e 3. 4 LD A parameter

s Blu e Gree n Viole t Nurnbe r o f fringe s 2 2 2 2 2 2 Fring e spacin g (pm ) 5.28 1 5.56 8 5.67 2 Bea mhal f

angl e (deg ) 2.64 8 2.64 8 2.64 8 Widt h o f measurin g volum e (mm ) 0.12 1 0.12 8 0.12 2 Lengt h o f

measurin g volum e 2.62 4 2.76 7 2.83 2 (mm )

... . i n the horizonta l 6-2 0 -5- 5 -5- 5 Velocit y / / \pip e rang e (m/s ) . .

i n the vertica l pip e -5- 5 6-2 0 -5- 5 I n order t o accuratel y locat

e the beams ' crossin g point , th e LD A probe s ar

e mounte do n a computer-controlle d3- D traversin g syste mwhos e minimu mste p i s 0.5mmi n al l three orthogona l directions . A Burs t

Spectru mAnalyse r

(BSA ) i s use dautomaticall y t o proces s th

e LD A burs t signals . Ever y recordo f th e experimenta l datainclude s particl e order number , transient

tim e i n the sampl e volume , thre e component s o f

particl e velocit y andth e relate dstatus . The n statistica l value s o f

particl e velocity an dparticl e number ar e calculate dfro mthe recorde dse t i n post processing . 3.3.2 Optic principle

of a ray crossing

a pipe wall

Optica l axi s

Figur e 3. 3 Refractio

n o f a ra y a ta curv e (th e incident

angl e 0j ; th e refractiv e angl e 0 r ; th

e curv e radiu s Ran dth

e curv e centr

e C ; y j andy , ar

e equa l t o th e distanc e fro mth

e refractiv e point

t o th e oplica l axis ; (y; , a t

) i s th e coordinal e o f

a inboun dra

y an d(y r , a, ) i s th

e coordinat

e o f it s refractio n ra

y ) I t i s know n tha

t three component s o f

aparticl e velocit y can b e measure db y usin g thre e pair s o f laser beam s wit h th

e sam e intersectio n poin t

wher e th e particl e crosses . Ever y velocit y componen t

i s proportional t

o the correspondin g Dopple r frequenc y originatin g fro mth e fring e intersecte db y apai r

o f laser beams . However , i n pip e flow measurement , th e crossin g poin t intersecte db y three pair s o f differen t

coloure dlaser

beam s may b e separatedint o thre e crossin g point s o r n o crossin g point

whe n thi s poin t

a t whic h th

e lase r beam s converg e on the outsid e i s shifte dinsid e th

e pipe . Sinc e ahollo w pip e comprise s tw o curve dsurfaces , refractio n occur s a t

4 1Ail investigatio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m Ih e pip e oute

r andinne

r surface s whe n abea

mtraverse s the pip e wall . A pai r o f beam s may be convergent

dependen

t on thei r inciden t conditions . Befor e discussin g th e optica l refractiv e effec t on apip e wall , le

t us conside r

th e refractio n o f

abeama

t acylindrica l surfac e dividin g medi ao f refractiv e indice s n , an

dn r , whic h i s show n i n Figur e 3. 3 (Th e subscript s o f i an dr mea n inciden t andrefractiv e respectively) . Accordin g t

o th e paraxia l for mo f

Snell' s law , the optica l relationshi p between th e inciden t

bea m an dit s refractiv e on

e ca n be give n a s (Pedrott

i e t al. , 2007) :

" 1 0 R\n.. n,. wher e th e first ite mon th

e righ t sid e i s define das th

e refractio n matri x M R .

, ; " v

Optica l axi s (3.1 )

Figur e 3 . 4 The geometri

c sketc h o f a bea m translatin

g a distanc

e L Wit h regar

dt o asimpl e translatio n i n ahomogeneou s mediu m(a s show n i n Figur e 3.4) , th e relationshi p o f

abea mpassin g throug h tw o point s wit h adistanc e L ca n b e describe das :

(3.2 ) " 1 L 0 1 where the firs t

ite mo n the righ t

sid e i s calle da

s th e transfe r

matri x M T Consequently , th

e matri x descriptio n o f ara y passin g throug h apip e wal l ca n b e simplifie da

s occurrin g twic e (refraction s a t eac h surface ) wit h atranslatio n betwee n th e surfaces . Th e optica l characteristi c o f

thi s proces s i s represente dby the syste mmatri x o f equatio n (3.3) : S = M

K2 M T M K , (3.3 ) where th e subscript s o f

1 an d2 mean pip e outer an dinne r

surfaces . Th e matrice s ar e multiplie d togethe r fro mrigh t

t o left . Th e abov e equation s ar

e limite dt o tw o dimensiona l optica l calculation s andar e not directl y use d i n three dimensional optica l calculation s i n pip e flo w measurement , fo r th e laser beam s o f

the LD A an dth

e norma l lin e o f the pip e surfac e ma

y no t b e i n a n identica l plan e an dthei r spatia l

4 2



## VES01707 7Chapte r 3 Hxtcndin g LD A fo rparticl e flo w measurementi n pipe s positio n shoul db

e expresse db y thre e dimensiona l vectors .

5 - 5 0 Figur e 3. 5 Th e schemati c o f aray crossin g apip e Figur e 3. 5 illustrate s th e optica l pat

h o f ara y crossin g apip e wall . Thi s ra y i s assume dt

o originate fro mth

e poin t M| . P ] i s it s firs t

refractio n poin t

a t the pip e outer

surfac e andVi i s it s secon drefractio n poin t

a t th e pip e inne r

surface . O i an dO i ar e th e circl e centre s o f

th e pip e oute r cross-sectio n throug h P | an dthe pip e inne r cross-sectio n throug h P 2 . Thes e tw o section s ar e perpendicula

r t o the x axis . A s such , the vecto r M t P t mean s th

e ra y outsid e the pipe . Th e vecto r P I P 2 show s the ra

y crossin g the pip e wal l an dth e vecto r P;M, display s the track o f th e ra y insid e the pipe . Sinc e apip e cross-sectio n i s astandardcircle , the normal vecto r o f apoin t on it s perimeter

i s the pip e radiu s pointin g outwar d(w e us e th e Capita l Bol dItali c t o expres s a vector) . In th e Cartesia n coordinat e syste mo f Oxyz , w e introduc e thre e spatial uni t vector s (V„ V,„ V r ) o f ara y describin g it s refractio n a t the poin t

P i o n the pip e oute

r surface . P I i s (h

e spatial referenc e point . F , i s th e uni t vecto r o f the inciden t

ray . V„ i s the uni t

vecto r o f the normal ra

y a t poin t P I o f th e surfac e an dV r i s the uni t

vecto r o f th e refractiv e ray . Accordin g l o Snell' s refractio n law , thes e thre e vector s shoul dlocate withi n the incidenc e plan e forme db y th e vecto r produc t o f V; an dV-,. Th e relationshi p amon g thes e thre e vector s ca n b e expresse das V,.-(-F„ ) = cosf?, . V r -{V

i xV n )=0 

### i i


### « ; 

### sin<9 . = « sinf

? (3.4 )

wher e (n „ n r ) ar

e the refractiv e inde x o f the mediu moutsid e an dinsid e th e pip e wall . Thus , th

e uni t vecto r o f the refracte dra

y ca n b e deduce dfro mequatio n (3.4 ) whe n th e inciden t

uni t vecto r

4 3



## VES01707 8A n investigatio n ol'particle dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m andIh e normal uni t

vecto r ar e known . I f

the refractio n poin t

P i i s als o known , th

e optica l pat

h o f abea mcrossin g apip e wal l ca n be fixe di n Cartesia n coordinates . Thi s refractio n poin t P i i s th e crossin g positio n o f

th e bea mintersectin g wit h the pip e outer surface . Subsequently , the coordinat e ofthi s poin t

ca n be conclude dfro mequatio n (3.5 )

2 ^ 2 

### D l V + Z = (3.5 )

wher e (a , b , c ) ar

e thre e component s o f

the inciden t

uni t vecto r o f abea man d(x 0 , yo , z 0 ) i s it s initia l positio n relate dt o aCartesia n coordinat e o f th e origi n poin t

o n the pip e centr

e line . Th e dependen t variable s (x , y , z ) ar e eac h give n function s o f a n independent

variabl e t

i n th e parametri c for mo f

abeam' s mathemati c equation . D i s the pip e outer diameter . I t i s clea r tha t ther e wil l b e fou r

step s a s show n i n Figur e 3. 6 t

o determin e the optica l pat h o f each bea mo f the LD A crossin g apip e wal l b y usin g equatio n (3.5 ) an d(3.4) . The n the actual coordinate s o f

th e measurement

volum e forme db y apai r o f laser beam s ca n b e calculate db y solvin g the crossin g poin t o f tw o line s describe db y the refractiv e uni t vecto r insid e th

e pip e an d th e refraction poin t

o n th e pip e inne r

surfac e fo r

eac h beam . Th e vecto ro f th e inciden t bea m (vj

) i s know n fro m th e pre arrange d LD A settin g Th e equation s o f pip e oute ran d inne r surface s (S„ , S,

) ca n b e obtaine d b yth e fixe d experimenta l rig
.

Determinin g th e crossin g poin t P , a t th e pip e oute rsurfac e (1 ) Equatio n (3.5 )

Determinin g th e refractiv e uni t vecto ro f ( V r) withi n th e pip e wal l (2 ) Equatio n (3.4 )

Determinin g th e crossin g poin t P 2 a t th e pip e inne rsurfac e (3 ) Equatio n (3.5 )

Determinin g th e refractiv e uni t vecto ro f (V r ) insid e th e pip e (4 ) Equatio n (3.4 ) 

# c En d

4 4



## VES01707 9Chapte r 3 Hxtcndin g LD A fo rparticl e flo w measurementi n pipe s Figur e 3. 6 Flo w char to f determinin

g th e optica l pat h o f a ra y crossin g a pip e wal l
3.3. 3 Optic paths of different

colour beams through

a pipe Accordin g t

o th e parameter s o f

LD A liste di n Tabl e 3.4 , th e hal f intersectin g angl e o f

each o f th e pair s o f lase r beam s i n th

e probe s o f

LD A i s 2.648° . No

w w e construc t

aCartesia n coordinate systemwith origi n a

t the centr

e o f apip e cross-sectio n whic h i s the measurement regio n i n ou r experiments . Wit h regar dt o the prob e combinin g tw o pair s o f beams , the plan e o f

th e prob e windo w andth

e tw o plane s forme db y tw o pair s o f beam s ar

e orthogona l wit h eac h other . I n thi s case , th e prob e axi s i s not

onl y the norma l lin e o f the prob e windo w but

als o the crossin g lin e o f tw o plane s fonnedb y tw o pair s o f lase r beams . No w the blu e beam s o f th e LD A ar

e arrange dt

o measur e on e velocit y componen t

i n th e x axi s o r

the horizonta l direction . Th e green an dviole t beams ar c buil t fo r detectin g the other

tw o component s o f

velocit y i n the plan e Oyz . Therefore , we ca n follo w the flo w char

t i n Figur e 3. 6 t

o calculat e th

e spatia l positio n o f

eac h bea mo f LD A insid e the pip e whe n the angl e o f the prob e axi s intersectin g wit h th e horizonta l plan e o f

Ox z i s know n an dthe crossin g point o f thre e pair s o f

laser beam s focu s o n the poin t o f the perimeter curv e o f th e pip e cross-sectio n intersectin g wit h th e horizonta l plane . Fo r example , i n th

e horizonta l pip e o f

ou r experimenta l ri g show n in Figur e 3.2 , th e pip e inne r an douter diameter s ar

e <j)75m man d(|)85m

mrespectively . Unde r

th e conditio n ofth e zero prob e angl e (meanin g tha

t the plan e forme db y the blu e beam s lie s o n th e horizonta l plan e o f

Oxz , th e crossin g poin t

o f th e blu e beam s i s initiall y adjuste dt o locat e a t the poin t

(0 , 0 , 42.5 ) mm , whic h i s th e crossin g poin t

o f th e perimete r

curv e o f

th e pip e cross-sectio n (x=0 ) intersectin g wit h th e plane Oxz . I

t i s clea r tha t th e cros s poin t

o f the blu e beam s wil l arriv e a t th e coordinate origi n whe n th e prob e i s move dabou

t th e distanc e (0 , 0 , -42.5 ) m malon g z axi s i f

ther e i s n o refractiv e surface . However , considering th e refractio n effec t

o f th e pipe , Figur e 3. 7 show s th e optica l path s o f tw o blu e beam s throug h th e pip e wal l an dthe crossin g poin t i s move dt o the poin t

(0 , 0 , -1.67 ) m mrathe r tha n the origi n (0 , 0 , 0 ) mm . Thi s indicate s tha t there i s adeviatio n o f - 1 67mmo n z axi s du e t o refractio n whe n the cros s poin t o f blu e beam s move s fro mthe poin t (0 , 0 , -42.5)m m t o th e expecte dpoin t

(0 , 0 , 0 ) a

t aprob e angl e o f

0° . The crossin g poin t

o f th e green beam s ca

n reach th e coordinat e origi n (0 , 0 , 0 ) whe n the prob e i s shifte dadistanc e (0 , 0 , -42.5 ) m mfro m th e initia l poin t

(0 , 0 , 42.5 ) mma

t the prob e angl e o f

0° . Th e optica l path s o f tw o green beam s ar e show n i n Figur e 3.8 . Comparin g Figur e 3. 7 wit h Figur e 3.8 , w e ca n observ e tha

t th e crossin g point o f th e blu e an dgreen beam s outsid e th e pip e i s separate dwhe n i t move s into th

e pipe .

4 5



## VES01708 0An invcshizalio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m

Prob e angle

= 0-G O ^ ~ cross-poin

t( 0.0 0 0.00- 1 67)im

m
5 0

Figur e 3. 7 Crossin

g poin to f blu e beam s shiftin g toward s th e pip e centr e lin e (Units : mm

)
4 0 J ' - - Prob e angle = 0.0 0 ! ~ - , cros s poin t(0.0 0 0.0

0 0.00 ) m m 2 0 J

Figur e 3. 8 Cros

s poin to f gree n beam s movin g t o th e pip e centr e lin e (Units : mm

) A s aresult , th

e burst-and-coincidenc e mode o f LD A wa s n o longe r

availabl e fo r

pip e flo w measuremen

t due t o the differen t

crossin g point s o f

the differen t

coloure dlase r

beams . Otherwise , we woul dneeda

n additiona l optica l arrangement t o calibrat e o r

adjus t each pai r

o f differen t colou r beam s t o converg e a

t the same poin t

i n the pipe . 3.3.4 Developing

the coordinate

transform

matrix for LDA pipe

flow measurement I n the previou s section , w e demonstrate tha t ther e i s adeviatio n betwee n the actual coordinat e an dth e expecte dpositio n whe n acrossin g poin t o f beam s i s shifte dint o apip e due t o the refractiv e effec t

a t th e pip e oute

r an dinne r

surfaces , Th e valu e o f thi s deviatio n i s dependen t o n prob e angle , beam s initia l condition s andpip e geometri c parameters . A s fo r th e specifi c experimental ri g show n i n Figur e 3. 2 an dthe LD A syste mdiscusse di n the sectio n o f 3.3.1 , onl y

4 6Chapte r3 Extendin g LD A fo rparticl e flo w measurementin pipe s Ih e prob e angl e affect s th

e deviations .
A y A . . Beams ' position s o n th e prob e frontlen s

x th e prob e coordinate locates a

tth e prob e center Figur e 3 . 9 Th e experimenta

l coordinat

e (Oxzy) , th e prob e coordinat

e (O'x'yV) an d th e initia l arrangemen

to f th e prob e In Figur e 3.9 , w e construc t a n experimenta l coordinate syste ma t the centr

e o f apip e cross sectio n an ddefin e the x axi s alon g the pip e centr e line , the y axi s opposit e t o th e gravit y directio n an dth e z axi s acros s the pipe . Z | i s th e crossin g poin t

o f th e z positiv e axi s intersectin g the pip e oute r surfac e an dZ 2i s th

e poin t o f the z positiv e axi s intersectin g th e pip e inne r

surface . Z | i s als o selecte da

s th e referenc e poin t

t o locate th

e beams ' spatia l coordinate s whe n th e prob e angl e i s known . Thus , th

e initia l positio n ofth e crossin g poin t o f al l colou r

beams locate s a

t Z| . Th e poin t O i s the origi n poin t

o f the syste mcoordinate . A s such , the angl e 0 whic h the plan e o f blu e beam s intersect s with th e horizonta l plan e Ox z o f th e coordinate syste mi s defineda s prob e angle . In othe r words , the prob e coordinat e whic h i s forme db y tw o pair s o f beams i s paralle l t

o th e referenc e coordinate transforme db y rotatin g the experimental coordinat e abou t th e prob e angl e alon g x axis . Whe n athre e dimensiona l travers e syste mcarryin g th e prob e move s fro mZ | t o Z zt o cros s th

e cross-sectio n alon g the z axi s (as show n i n Figur e 3.9) , the actual position s ofth e crossin g poin t o f blu e beam s agains t

the differen t

prob e angle s ar

e show n i n Figur e 3.10 , whic h illustrate s th e deviation s o f

(y'-y ) an d(z'-z ) agains t z under the differen t

prob e angl e 0 . Th e variation s o f (z'-z ) sho w tha t ther e alway s exit s ashif

t betwee n a

n expecte dpoin t

an dit s correspondin g actual positio n i n th

e z directio n no matter

wha t th e prob e angl e is . Bu t

alarge r th e prob e angl e result s i n alarger

deviatio n ofth e crossin g poin t awa y fro mit s expecte dpositio n (y'-y ) o n the y axi s an d asmalle r shif t o f (z'-z ) i n th

e z axis . Thi s i s clearl y show n i n the pip e centr e region . Fo r

smalle r th e prob e angle s lik e 0 ° and5° , the variatio n o f (z'-z ) agains t

z i s almos t

lik e astraight

lin e whic h mean s tha

t the z coordinate o f

a n actua l blu e beams ' crossin g poin t ha s a-1.67mmshif

t t o it s expecte dz coordinate . In contrast , the variation s o f (y'-y ) clearl y displa y tha t the larger

the prob e

4 7


## VES01708 2An investigatio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m angl e is , th

e large r th e shif t betwee n y an

dy ' is . Fo r

example , the differenc e betwee n y ' andy i s almos t equal t o zer o unde r the prob e angl e zero . An da t every prob e angle , the maximu m deviatio n i n y direclio n occur s a t shiftin g th

e blu e beams ' crossin g poin t t o th e sectio n centr

e o r the coordinate origi n point .

-1.5 5 -1. 6 -1.6 5

-1.7 5 -3 0
0 -0. 2 E ^ -0.4 - -0. 6 -0. 8 0 1 0 z (mm ) Prob e Angle(° ) 0 "

. - 5 o 10 ° 15 ° 20 =

-2 0 -1

0 0 1

0 2

0 3

0 4

0 z (mm ) Figur e 3 .1 0 Variation

s o f th e crossin g poin to f blu e beam s agains tprob e angl e Note : (y , z ) i s th

e expecte dpositio n and(y \z' ) i s th e actua l positio n Unde r th e sam e shiftin g process , Figur e 3.1 1 display s the deviation s o f (z'-z ) an d(y'-y ) o f

th e gree n beam s a

t differen t

prob e angle s whe n thei r crossin g poin t

move s fro mZ | t

o Z 2t o cros s th

e pip e alon g th

e z axi s (a

s show n i n Figur e 3.9) . I n general , the variation s o f (z'-z ) sho w asimila r tendenc y a

t th e differen t

prob e angles , i n whic h th e minimu mshif

t occur s i n the pip e centr e an d th e maximu mshif

t happen s clos e t o the pip e wal l i n th e z axis . B y contrast , th e variation s o f

(y'

- y ) sho w tha

t ther e i s almos t

n o shif t between y ' an dy under smaller prob e angle s lik e 0 ° an d5° . Bu t fo r prob e angle s larger

than 5° , ther

e exist s alarg e discrepanc y betwee n y ' andy whe n the gree n beams ' crossin g poin t i s furthe r

fro mth e pip e centre . Compariso n o f Figur e 3.1 1 with Figur e 3.1 0 show s tha

t th e identica l crossin g poin t o f blu e an dgreen beam s outsid e the pip e wil l b e separate dwhe n the crossin g poin t move s int o th

e pipe .

4 8


## VES01708 3Chapte r3 Intendin g LD A fo rparticl e flo w measurementi n pipe s

E -0. 5 E

Prob e Angle(° ) -1. 5 ' • 1 i 0 ° -3 0 -2

0 -1 0 0 10 20 3 0 z (mm ) 5 ° 10 = 0.0 1

E 0 £ -0.0 1 15 » 20 °

-0.0 2 ! 1 < -3 0 -2

0 -1 0 0 1 0 2 0 3 0 40 z (mm ) Figur e 3.11 Variation

s o f th e crossin g poin to f gree n beam s agains tprob e angl e Note : (y , z ) i s th

e expecte dpositio n and(y \z' ) i s the actua l positio n Considerin g the prob e angl e a s aconstant

o f -5° , Figur e 3.1 2 (a

) an d(b ) sho w the actual coordinate s o f

th e blu e an dgreen crossin g point s i n th e horizonta l sectio n o f

th e ri g respectively , whe n the travers e syste mcarryin g the prob e i s linearl y shifte dt o acces s th

e whol e pip e cros s section . Generally , tw o colou r crossin g point s hav e les s discrepanc y fro mthei r norma l position s i n th e pip e mi dpar

t tha n i n the pip e top o

r botto mregions . Al l th

e crossin g point s li e i n th e sam e plan e o f Oxz . Figur e 3.1 3 (a

) an d(b ) displa y the spatial position s o f blu e an dgreen crossin g point s i n the vertica l sectio n o f th e rig pip e separatel y over the entire cross-sectio n a t aprob e angl e o f -5° . Bot h tw o colou r

crossin g point s hav e more deviation s fro mthei r expecte dpositio n i n th e righ t or lef t regio n tha

n i n the pip e centre . Comparin g Figur e 3.1 3 wit h Figur e 3.12 , w e ca n se e tha t bot h colou r crossin g point s i n the vertica l pip e no t onl y deviat e fro mthei r norma l position s bu

t als o ar e n o longe r

o n th e sam e plan e o f

apip e vertica l cross-section , whic h mean s tha t ther e i s adeviatio n i n the y axis , althoug h th e movement

ofth e 3 D travers e syste mi s limite d t o th e plan e o f

Oxz . Therefore , i n orde r t o compensat

e the deviatio n i n y axis , w e shoul dad da n additiona l y valu e a

t eac h sampl e poin t

fo r keepin g sampl e point s o n apip e vertica l cross-section , whe n settin g the shif

t coordinat e o f

the travers e system . O n th e other hand , ther

e als o exist s apractica l over-curren t proble mfo r

th e photomultiplier s in the LDA , whic h i s cause db y th e stron g intensity o f

the reflecte dligh t

o n the pip e outer

surface . Th e over-curren t

conditio n wil l make the linea r scal e capabilit y o f

the photomultiplier s worse . I n addition , th

e laser sourc e o f

th e LD A syste mha

dt o be powerfu l enoug h t o measur e th e velocit y

4 9


## VES01708 4A n investigatio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m o f amicr o particl e lik e smok e (siz e les s tha

n 3 0 p.m) , whic h i s use dt o trac e flui ddu e t

o it s smal l Stoke s number . I

n our experiments , ih e trade-of f between laser

powe r an dth e prob e angl e wa s testedt o select tw o dat asets o f (0.8w , 0° ) an d(1.6w , -5°) . A zero prob e angl e minimize s the crossin g poin t

deviatio n du e t

o th e refractio n effect . Gree n Beam . P'ob e Angl e (-5

' )

(a ) Coordinate s o f

th e blu e beams ' crossin g poin t(b) Coordinate s o f th e green beams ' crossin g poin t Figur e 3.1 2 I n th e horizonta

l pip e a tth e -5° prob

e angl e Accordin g t

o the abov e discussions , atotal o f 104 7 sampl e point s ar

e arrange dt

o occup y the whol e are ao f

ahorizonta l or

vertica l cros s sectio n b y shiftin g the travers e system . Th e spatial resolution s o f

thes e sampl e point s were define da s 1m mi n the y directio n and2m mi n th e z directio n respectively . Thu s atransfor mmatri x ca n b e calculate di n advance , whic h i s use dt o inde x ashif

t coordinate o f

the travers e syste mwit h asampl e poin t i n pipe .

Gree n Be2m . Prob

e Angl e (-5" iBiu e Seam . Prob

e Angle"!-: , I

(a ) Coordinate s o f

ih e blu e crossin g poin t(b) Coordinate s ofth e green crossin g point Figur e 3.1 3 I n th e vertica l pip e a tth e -5 ° prob

e angl e 3 . 4 SAMPL E RAT E O F LD A FO R GAS-SOLI D FLO W MEASUREMEN T Accordin g t

o Shannon' s samplin g theorem , i t i s necessar

y t o sampl e acontinuou s signa l a t arat e greate r tha n twic e it s highes t

frequenc y component

fo r measurin g i t

exactly . Th e twic e highes t frequenc y o f

acontinuou s signa l i s als o calle dNyquis t frequenc y or

Nyquis t rat e (Smith , 2003) .

5 0


## VES01708 5Chapte r3 Extendin

g LD A fo r particl e flow measuremen

ti n pipe s However , particl e signal s recorde db y LD A a t ameasurement

poin t insid e apip e are discret e wit h arando mfluctuatio n du e t o th e loca l fluidcondition s an dparticle s impactin g states . Thes e signal s ca n b e considere da s anumerica l even

t lik e adiscrete-tim e rando mproces s whic h i s illustrate di n Figur e 3.14 . At K

P m kI
O - O o o o- o o o I K+ 1 k M T Figur e 3.1 4 Th e sketc

h o f particle signal

s recorde d b y LD A Wit h regar dt o LD A measurement , Figur e 3.1 4 show s th e signa l characteristic s o f particl e velocitie s recorde db y LDA . A tota l o f N particle s ar

e assume dt o cros s the LD A fring e a t th e sampl e poin t

P withi n atim e interva l T . Th e parameter u pexpresse s aparticl e instantaneou s velocity . Th e parameter

K i s use dt o labe l the order o f particle s passin g throug h P an dAt* c mean s th e tim e interva l betwee n particl e K an dparticl e (K+1) . Whe n thes e particle s ar e ver y small , fo r example , seedin g particle s lik e ammoniu mchlorid e smoke (mean siz e 0. 6 pm) , the measure d L D A dat arepresent

th e loca l velocit y o f

th e ai r phas e a t th e poin t

P . Sinc e seedin g particle s ar e fm e wit h asmal l Stoke s Numbe r an dhav e agoo dabilit y t o follo w th e fluid , the time-serie s signal s o f

{u p } recorde db y LD A are simila r an donl y dependent

o n the loca l ai r

phas e state . I n th e cas e o f

astead y flo w measurement , th e se t o f {u p } shoul dhav e asmal l deviation . Hence , the tota l number

o f signal s {u p } woul dhav e les s influenc e o n calculatin g its mea n velocity . However , fo r gas-soli dflo w measurement , particle s o f soli dphas e ar e considere das the seedin g particle s fo r LD A measuremen

t an dthe y ar e differen t i n term s o f

siz e an dinitia l conditions , a s wel l a s density , fo r

amulti-materia l soli dphase . Th e signal s {u p } recorde db y LD A a t th e poin t

P are no t onl y relate dt

o the loca l ai r

phas e stat

e bu t als o dependent

o n th e particl e properties . Item s i n the set {u p } ma y hav e larg e discrepancies . Compare dwit h measurin g th e ai r phas e velocity , particl e signal s fo r

soli dphas e measuremen t are discret e wit h an unequa l separatio n distance . The n the loca l mean velocit y o f

soli dphas e wil l b e affecte db y particl e numbe r i n the velocit y set

{u p } , whic h ca n b e describe da s equatio n (3.6 ) A M



### « P 

### = {u pk 

### ,k = l,A ,N} (3.6 ) up = 2X * 

### N where T i s the measurement perio dan dN i s the tota l number o f particle s crossin g the measuremen

t fringes . I n the grou p equatio n (3.6) , th e first expressio n mean s the su mo f th e tim e interval s betwee n particle s equal s the tota l measurement time . Th e secon dmean s tha t the

5 1


## VES01708 6A n investigatio n o f particl e dynamic

s in a dilut

e phas e pneumati

c conveyin

g syste m measure dinstantaneou s velocit y woul db e on e o f th e item s i n th

e particl e velocit y countabl e sampl e space . Th e thir di s the equatio n fo r calculatin g particl e mea n velocit y whos e accurac y i s obviousl y relate dt

o th e tota l numbe r

an dth e deviatio n o f

particl e velocit y se

t {u p } . Then , i f

t m j n i s the minimu mtempora l interva l betwee n tw o adjacen t particle s crossin g th e measurement point , i t ca n b e describe da s
Thus , i t woul db e possibl e t o recor deac h ite mi n th e sequenc e o f particle s show n i n Figur e 3. 9 i f th e sampl e frequenc y o f LD A i s equal t o o r

greater than l/t m i „ an dthe othe r tim e interva l At k

can b e assume das Att/tmb ^ ( n i s an integer) . Sinc e th e minimu mtempora l interva l a t aloca l poin t i s muc h affecte db y th e loca l soli dconcentratio n an dthe correspondin g boundarie s aroun dthe point , i t wil l chang e poin t

b y poin t o n awhol e pip e cross-section . I n contras t t o continuous-tim e signals , whic h hav e aminimu msampl e rate o f twic e it s highes t

frequenc y fo r

avoidin g aliasing , ther e i s n o Nyquis t

frequenc y fo r

adiscrete-tim e signal . A s such , w e wil l demonstrate ho w t o determin e th e suitabl e sampl e frequenc y o f LD A fo r ou r experiment s discusse di n Chapte r 4 .

I n thi s chapter , LD A application s fo r gas-soli dflow researc h hav e bee n reviewed , whic h show s that there i s stil l alac k

o f paper s discussin g the refractiv e effec t an dth e sampl e rat

e i n gas-soli d pip e flo w measurement b y usin g LD A i n detail . Sinc e th e refractiv e effec t du e t o the pipe' s curve dsurfac e ca n no t

b e ignored , w e hav e develope dagrou p o f mathematica l equation s an d demonstrate dfh e calculation s o f th e transfor mmatri x fo r mappin g the actua l position s o f the measurement

volum e o f

LD A i n tli e pip e b y shiftin g the travers e syste maccordin g t o prob e angle . I n addition , particl e siz e i n gas-soli dflow ha s aver y wid e distributio n an dparticl e velocit y i s dependen

t o n man y factor s lik e Stoke s Number , dra g coefficien t an dloca l ai r

velocit y etc . Whe n L D A i s applie dt o measure the loca l velocit y o f soli dphase , whic h i s average dfromvelocitie s o f particle s passin g throug h asampl e point , asequenc e o f discrete-tim e signal s ca n b e recorded . I n orde r t o calculat e accuratel y the time-average dvelocit y a t aloca l point , th e sampl e frequenc y o f L D A shoul db e experimentall y determined . Theoretically , thi s sampl e rat e shoul db e a

t leas t equa l t o o r greate r tha n l/t m i „ whic h i s describe di n equatio n (3.7) . (3.7 )

3. 5 SUMMAR Y

5 2


## VES01708 7

# Chapte r 4 Experimenta l studie s of cross-sectiona l characteristic s of ai r velocity i n pipe s usin g th e extende d LD A Techniqu e

In this chapter, the extended LDA technique was applied to measure the cross-sectional distributions of airvelocity on two horizontal pipe cross sections and eight vertical pipe cross-sections behind a horizontal-to-vertical

90° bend

(R/D=1.3) in the rig. On the horizontal cross-sections, the experimental

contours of

the axial airvelocity (Vox) show an annular feature. On the verticalcrosssections, each cross-sectional distribution of

the axial airvelocity (Uay) has been shown to be like a horseshoe. A secondary flow including two circulations has also been shown in the cross-sectional distributions of

the radial

airvelocity (U^) on the vertical cross-sections close to the bend outlet. At the furtherdownstream sections, both the above features explored by U

ay and Vox gradually become weak. A comparison of the experimental

data and

the numerical

results by CFD indicate good agreement.

4. 1 INTRODUCTIO N I n th e previou s sections , w e hav e discusse dho w t o calculat e the transfor mmatri x fo r mappin g th e actual position s o f the measurement

volum e o f

LD A i n apip e accordin g t o the shiftin g coordinat e o f

the travers e syste man dth e importanc e o f aprope r LD A sampl e rat

e fo r gas-soli d flo w measurement . Wit h regar dt o th e experimenta l rig show n i n Figur e 3.2 , th e transfor m metric s a

t th e 0 ° an d-5 ° prob e angle s respectively , whic h ha dbee n calculate di n advanc e accordin g t

o th e principl e discusse di n Chapte r 3 , were use dt o arrang e th e shif t coordinate s o f the traversin g syste mt o mak e the crossin g poin t o f th e lase r beam s abl e t

o acces s awhol e pip e cross-section . A t the 0 ° prob e angle , the experimenta l coordinat e i s paralle l t o the orthogona l prob e coordinat e (a s show n i n Figur e 3.9 ) whic h i s forme db y tw o pair s o f the lase r beam s (blu e an dgreen) . Th e measure dsignal s usin g th e blu e beam s an dth e gree n beam s ar e correspondin g t

o th e axia l ai r velocit y (U a x ) an dth e vertica l ai r velocit y (U a y ) i n ahorizonta l pip e respectively . B y contrast , th eChapte r4 Hxpcrimenta

l studie s of cross-sectiona

l characteristic

s of ai rvelocit y i n pipe s measure dsignal s usin g the blu e beam s an dthe gree n beam s ar

e correspondin g t

o th e horizonta l ai r velocit y (U M ) andth

e axia l ai r

velocit y (U a y ) i n avertica l pipe . Whe n the prob e angl e i s no t equa l t o 0 ° (lik e -5°) , thi s prob e coordinate wil l be paralle l t o th e referenc e coordinat e transforme db y rotatin g th e experimenta l coordinat e about -5 ° alon g x axis . I

n thi s case , th e dat

a measure db y th

e blu e beam s stil l represent s the ai r x velocit y (U a x ) , bu t

th e dat ameasure db y th

e green beam s ar

e not directl y equal t

o th e ai r vertica l velocit y (U a y ) , fo r ther e i s the -5 C intersectio n angl e betwee n them . I n order t o avoi duncerlainty du e t o th e separatio n phenomeno n o f the crossin g point s o f

differen t colou r beam s (a

s discusse di n Chapte r 3) , th e 0 ° prob e angl e wa s use dt o investigat e th

e horizonta l an dvertica l characteristic s o f ai r velocit y an dthe -5°prob e angl e wa s onl y applie dt o stud y th e horizonta l characteristic s o f ai r velocit y i n the followin g sections . A total o f

1047 measuremen

t point s wer

e arrange dove r

apip e cross-sectio n b y shiftin g the three

dimensiona l travers e syste maccordin g t o th e pre-calculate dtransfor mcoordinates . A suitabl e sampl e rat

e o f LD A wa s selecte das the sam e a s tha t fo r particl e velocit y measurement . I t wa s 10 K H z determine db y th

e experiment s i n Chapter 5 . Fo r ai r velocit y measurement , the seedin g particle s wer

e produce db y burnin g abundl e o f incense . Th e smok e i s les s tha n lOp m(Fan g e

t al. , 2002) .

4 . 2 MEASURIN G TH E CROSS-SECTIONA L CHARACTERISTIC S O F TH E AXIA L AI R VELOCIT Y (U a x ) I N A HORIZONTA L PIP E

•20 0 R/D=1. 3 Umt. mnr j H y | (R/D=1.3 , Ri

s th e ben d radiu s 100m m an d D i s th e pip e diamete

r 75mm ) Figur e 4. 1 2 D schemati c diagram o f tw o selecte d cros s section s i n the ri g horizontal pip e I n the horizonta l pip e o f ou r ri g show n i n Figur e 4.1 , tw o cross-section s whic h ar e 200m man d 300mmaway fro mthe elbo w inle t respectivel y wer

e selecte das the measuremen t regions . Here , th e experimenta l coordinat e locate s a t the centr

e o f the elbo w inlet , fh e x positiv e axi s denote s

5 4


## VES01708 9A n investigatio n of particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m flui ddirectio n o n th

e pip e centr

e line . Th e y negativ e directio n i s o n th e gravity directio n andthe z positiv e axi s signifie s inwar dtoward s the paper . I t i s know n tha

t the turbulen t

velocit y profil e i n acircula r pip e ca n b e describe db y a n empirica l equatio n (4.1) , whic h wa s summarize dfro mJ . Nikuradse' s experimenta l dat a(Schlichtin g H. , 1955) .

wher e u i s the loca l tim e average dvelocity ; u m i K i s the maximu mvalu e o f u, ; Ri s th

e pip e radius ; r i s th e distanc e fro mthe pip e centr e an dn i s the empirica l exponent facto r dependen

t on Reynold s number . Thi s equatio n i s als o calle d1/n-t h powe r la w o f ai r velocit y profil e i n pipe . Accordin g t o J . Nikuradse' s experimenta l data , th e valu e o f

the exponent

n i s n= 6 a

t the lowes t Reynold s number

Re=4xl0 3 ; i t

increase s t

o n- 7 a t Re=110xl0 3 . Fo r

ou r flui dconditio n o f

ai r conveyin g velocit y I2m/ s i n rj)75m mpipe , it s Reynold s number i s equa l t o 56x10 1 fo r

ai r densit y 1.12kg/m 3 . A s such , th

e n i s chose n a

s 7 i n ou r experiments . In orde r

t o compare convenientl y th e cross-sectiona l dat ao f

ai r velocit y wit h the empirica l profil e estimate db y equatio n (4,1) , the experimental dataan dthe empirica l profil e ar e plotte dtogether . Unde r the conditio n o f

ai r conveyin g velocit y 12m/ s an dth e -5 ° prob e angle , th e axia l characteristic s o f

ai r velocit y wer

e investigate dan dthe experimenta l dat aar e illustrate di n Figur e 4. 2 andFigur e 4.3 . l n orde r t o compar

e convenientl y the cross-sectional datao f ai r velocit y wit h the empirica l profil e estimate db y equatio n (4.1) , the experimental dat aan dthe empirica l profil e ar e plotte d together . Figur e 4.2(a ) show s ai r velocit y profile s alon g the y axi s o n tw o cross-section s a t x= - 20 0 an d-300mm . Similarly , profile s o f the axia l ai r

velocit y (U x ) alon g th e z axi s o n th

e tw o section s ar

e displaye di n Figur e 4.2(b) . Th e maximu mvalu e o f ai r velocit y (U max ) whic h i s use d t o normaliz e the experimental datao f ai r velocit y i s selecte dfro mth e dat ao f ai r velocit y o n th

e cross-sectio n x=-300mm . A s such , the maximu mnormalize dvalue o f ai r velocit y o n th

e other cross-sectio n x=-200mmi s equal t o 0.9 7 rathe

r tha n 1 . Thi s discrepanc y i s possibl y du e t o experimenta l rando merror , sinc e the measurement s o n the tw o cros s section s were carrie dou t separately withou t

coincidence . Compariso n o f th e experimenta l dat awit h the empirica l velocit y profil e indicate s tha

t they hav e agoo dagreemen t an dasimila r

shape . Th e tota l deviatio n between th

e experimental dataan dthe valu e give n b y Eq . (4.1 ) i s les s tha n 10% . Th e maximu m discrepanc y occur s a

t th e pip e boundary (r/R>0.82) . I t i s als o observe dtha

t the ai r velocit y profil e alon g th

e y axi s (z=0 ) i s close r t o th e empirica l one-sevent h power profil e tha

n ai r (4.1 )

5 5


## VES01709 0Chapte r 4 Hxperimcnta

l studie s of cross-sectiona

l characteristic

s of ai rvelocit y i n pipe s velocit y profil e alon g th e z axi s (y=0) . Moreover , the ai r velocit y profil e o n the y axi s (z=0 ) i s almos t symmetrica l alon g th e pip e centre line , bu t th e ai r velocit y o n th

e z axi s (y=0 ) i s somewha t skewed . There i s abia s i n th e centr e velocit y toward s the pip e bottom . Ai rwlocit

y profil e a ty= 0 1 0.8 ; 0.6i 0.4 | 0. 2 c : oi - -0. 2 j -0.4 1 •0.6 1 -0.8 1 x=-200mm, mea n U =11.8

9 m/ s x=-3O0mm

, mea n U =11,5

0 m/ s one-se«nt h powe

r profil e

-1 L

1 0. 8 0. 6 0. 4 0. 2 0 -0.2 -0.4 0. 8 0.8 5 0. 9

U x ' U TM (a) Ai ryslocit

y profil e a tz- 0

x=~200mm

, mea n U =11.5

0 m/ s x=-300mm , mea

n U =11.1 1 m/

s one-sevent

h powe r profil e

-1 : 1 i 0.7 0.7

5 0,

8 0.8 5 0. 9 0.9 5 1

U >: /U ma! < (b ) Figur e 4. 2 Velocit y profile s ofth e axial ai rvelocity (U* ) a tx=-200 , -30 0 m m alon g (a ) y axi s and (b ) z axis , unde r ai rconveyin g velocit y 12m/ s Wit h regar

dt o the cross-sectiona l distributio n o f ai r velocity , Figur e 4. 3 clearl y show s th e contour s o f

ai r velocit y o n tw o pip e cross-section s on whic h tw o su b contou r

diagram s displa y a

n annula r natur e o f th e cross-sectiona l distributio n ofth e axia l ai r velocity . I

t i s clea r tha t the axia l ai r velocit y decrease s graduall y fro mpip e centr e t o pip e wal l o n eac h cros s section . However , th e fastes t regio n o f

th e axia l ai r

velocit y doe s not

exactl y locate a

t the pip e geometri c centre , havin g asmal l deviatio n toward s the z-negativ e direction . Bu t i n the y direction , ther e i s no obviou s deviation . Thi s kin do f

deviatio n indicate s tha

t the actual ai r

flo w i n th e ri g i s not

ideal .

5 6A n mvcsligitiior to f particl e dynamic

s i n a dilut e phas e pneumati

c conveying syste

m
40 : 2 0

-2 0 s x=-200m m

-4 0 s -4 0 -2 0 0 2 0

z(mm ) 4 0

-
2 0
1 °!; ?

-2 0 |

4 0 -40 >

-4 0 x=-300m

m

-2 0 0 2 0 z(mm ) 4 0
Figur e 4. 3 Cross-sectiona l distributio n o f the axia l ai rvelocit y distributio n (U x ) a ttw o horizontal cross-section s o f x=-20 0 an

d -300mm fro m the ben d inle trespectively , unde r ai rconveyin g velocit y 12m/s) 4. 3 AI R VELOCIT Y I N TH E RI G VERTICA L PIP E AFTE R A 90 ° BEN D Sinc e the effec t

o f gravity on ai r

ca n b e ignored , th

e velocit y characteristic s o f singl e phas e ai r

i n ahorizonta l or

vertica l pip e shoul db e identica l i f flui dcondition s a

t inle t ar e th e same . However , larg e discrepancie s wil l occu r whe n avertica l pip e i s mounte ddownstreamo f aconnectin g elbow . S o far , ther

e hav e bee

n man y studie s t o investigate the elbo w effec t o n gas-soli dflow . Thi s effec t i s als o calle dthe ropin g phenomenon . Forkee r e t al . (2004 ) reviewe dthe relate dpapers . However , ther e i s stil l lac k

o f experimental ai r

velocit y datafo r

singl e phas e flo w i n avertica l pip e behin d a n elbow . I n thi s section , w e wil l publis h ou r

experimental dat ao f

ai r velocit y distributio n o n a scrie s o f cross-section s alon g the vertica l par t o f the rig .

R/D= l . 3 Sinn : rnn i (R/D= l .3 , Ris th

e ben d radiu s 100m m an d U is th e pip e diamete

r 75mm ) Figur e 4. 4 2 D schemati c diagra m o f cros s section s alon g th e vertica l pip e behin d a 90 ° ben d (R/D=1.3 , Ri s th e ben d radiu s 100m

m an d D i s pip e diamete r 75mm ; 0 D is 15m m awa y fro m th

e bend outlet) . I n the experiments , ai r

conveyin g velocit y wa s adjuste dt o lOm/ s an dthe incens e smok e wa s

5 7


## VES01709 2Chaplc r4 H\perimcnla

l studie s o f cross-sectiona

l characteristic

s of ai rvelocit y i n pipe s agai n useda

s Ih e seedin g particles . A tota l o f eight cross-section s fro mO

D t o 7 D downstrea

mo f th e elbo w exit , wit h a75mminterva l spacin g equivalen t t o on e pip e diameter

(D) , wer

e selecte d a s measuremen

t region s alon g th

e vertica l leg . Th e origi n o f th e referenc e coordinate wa s chosen t o b e the centr

e ofth e cross-sectio n OD , a s show n i n Figur e 4.4 . Th e sectio n O D i s about

15m m awa y fro mIh e ben doutlet . O n eac h section , atota l o f 27 4 sampl e point s wit h a4mminterva l distanc e i n the x andy direction s wer e selecte dt o gri dawhol e cros s section . Th e experimental datao n aserie s o f cross-section s alon g th

e vertica l pip e ar

e illustrate di n Figur e 4. 5 fo r th e axia l ai r

velocit y U a yan dFigur e 4. 7 fo r th e radia l ai r

velocit y Ua

x respectively . Th e correspondin g numerica l data , whic h hav e bee n simulate dfo r singl e phas e ai r

b y usin g th

e standar dk - e mode l i n th

e commercia l Computationa l Flui dDynamic s softwar e Fluen t 6.3.2 6 (Fluen t Inc. , 2006) , ar

e plotte di n Figur e 4. 6 an dFigur e 4.8 . Compare dwit h the annula r natur e o f the axia l ai r

velocit y Ua

x o n ahorizonta l pip e cross-sectio n show n i n Figur e 4.3 , cross-sectiona l distribution s o f th e axia l ai r

velocit y U a yi n th

e vertica l pip e d o not retai n suc h annula

r structure du e t

o th e ben deffect . Especially , on the sectio n OD , th e slowes t region s o f

U o y (th e dar

k blu e colour ) ar

e locate da

t th e pip e centr

e an dth e regio n clos e t

o the pip e inne r

wal l (th e x negativ e axis) . Th e fastes t regio n o f

U u y(th e dar k re dcolour ) i s aroun d the regio n clos e t

o th e pip e oute

r wal l (th e x positiv e axis) . Generally , ahorseshoe-like featur e i s show n o n the cross-sectiona l distribution s o f U a ya t OD . Thi s horsesho e ca n b e als o observe do n cross-sectiona l distribution s o f U a ya t the furthe r

downstreamsections . Compare dwith tha t a t th e sectio n OD , th

e axia l ai r

velocit y U a yi s graduall y accelerate dinsid e the horsesho e an d decelerate doutsid e i t

fro mthe sectio n I D t

o 7D . Consequently , the differenc e o f U a ybetween insid e an doutsid e th

e horsesho e i s narrowed . Th e total scal e number o f isoline s i s decreased , whic h show s th

e homogenou s are awithi n acertai n isolin e enlarged . Wit h regardt

o the numerica l simulation s o f ai r singl e phas e pip e flow , th e evolutio n ofth e axia l ai r velocit y (U a y ) show n i n Figur e 4. 6 i s illustrate dthroug h cross-sectiona l distribution s o f U a y alon g the vertica l pip e behin da n elbo w (R/D=1.3) . Here , the geometri c parameter s o f th e numerica l mode l ar

e th e sam

e a s thos e o f

th e experimenta l ri g show n i n Figur e 4.4 . Ai r conveyin g velocit y a

t th e pip e inle t

i s lOm/ s i n the smoot

h glas s pipin g o f

th e rig . Th e detaile d conten t o f numerica l equation s an dthe relate dnumerica l parameter s ar e thos e discusse di n Chapter 2 . I t i s clear tha t the elbo w apparentl y affect s the axia l ai r velocit y distribution s i n th e vertica l pip e behin dabend . Whe n the mai n directio n o f ai r flo w i s change dfro mx positiv e axi s t o y positiv e axis , th

e annula r structure o f

th e cross-sectiona l distribution s ofth e axia l ai r velocit y (U a x ) i n ahorizonta l pip e i s als o modifie dint o ashap e lik e ahorsesho e i n th e vertica l pipe , wher e ai r run s faster

i n the pip e outer

wal l tha n i n the regio n ofth e pip e centr e or th e pip e inne r

5 8


## VES01709 3A n invesligalio n o f particl e dynamic

s i n a dilut e phas e pneumati

c conveyin

g syste m wal l Th e slo w regio n o f U, l yi s marke das th

e blu e on the sectio n O

D andthe green o n the sectio n o f 2D . The n it s colou r

i s develope da

s the littl e dar

k yello w o n th e sectio n o f 7D . Al l thes e colou r variation s mea

n increas e tendenc y o f

U a yi n th e pip e centr

e region . cross-sectiona l distribution s o f U (m/s ) a v 4 0 1

5 0 50
4 0 2 0 0 -2 0 -4 0 -5 0 0

z(mm ) 5 0 4 0 2 0 0 -2 0 -4 0 — -5 0 3D

0

z(mm ) 5 0

Figur e 4. 5 Experimental cross-sectiona l distribution s ofth e axia l ai r velocit y (U a y , m/s ) alon g th e vertica l pip e behin d a 90 ° bend (R/D=1.3 , Ris th e ben d radiu s 100m

m an d D i s pip e diamete r 75mm ; 0 D is 15m m awa y fro m th e ben d outlet) .

5 9


## VES01709 4(.'hapte r 4 Kxperimenla

i studie s of cross-sectiona

l characteristic

s of ai rvelocit y i n pipe s

1 2 . Q • 11. 5 ' 7 D 11. 0 10. 5

• 6 D i 

# a . a 9 . 5 

### g . a 5 D B . 5 8. 0 AO 7 . 5 

### 7 . a 3 D B . 5 B. O 

### ^liiSii ^

" 2 D 5 . 5 5 . 0 1 D

- 4. 5 

# u H E

• 4. 0 O D
Contour s o f Y Velocit y ( m / s ) De c 01 , 200 8 ' F L L E h T 6. 3 [3d , pbns , ske ) Figur e 4. 6 Numerica l cross-sectiona l distribution s o f th e axia l ai rvelocit y (U, „ , m/s) alon g th e vertica l pip e behin d a 90 ° ben d (R/D= l .3 , Ri s th e ben d radiu s 100m

m and D i s pip e diamete r 75mm ; OD i s 15m m awa y fro m th e ben d outlet) . Th e compariso n o f

Figur e 4. 5 an dFigur e 4. 6 not onl y show s the simila r structur e o f the axia l ai r velocit y (U a > ) distributio n o n eac h sectio n bu t als o illustrate s th

e simila r evolutio n o f

U a yfro m 0 D t o 7D . O n each section , th e numerica l datavalidat e tha t the axia l ai r

velocit y i s faste r

on th e outsid e o f

the horsesho e tha

n insid e it . Also , the axia l ai r velocit y insid e the horsesho e graduall y increase s an ddecrease s outsid e the horseshoe . A s such , the tota l scal e numbe r o f U a ydecrease s an dth e differenc e o f

U a ybetwee n insid e th e horsesho e an doutsid e i t tend s t o lessen , whic h show s th e cross-sectiona l distribution s o f U a yinclinin g t o the homogenou s durin g ai r flo w development

furthe r downstream .

6 0


## VES01709 5A n investigatio n o f pnrltci e dynamic s i n a dilut e phas e pneumati c conveyin g syste m cross-sectiona l distribution s o f U (m/s ) 4 0 4 0 - O D 1 D 2 0 2 0 

## o ! V i i I

T ; " E 0 

### c 

# \;- -2 0 % 

### /I -2 0 -4 0 -5 0 0 5 0 -40- ' -5 0
4 0 2 0 0 - -2 0

^ 0 2 D

-5 0 z(mm ) * bis* 0 z(mm )

5 0 40 -

20 - 0 - -2 0 -4 0 3 D

-5 0 0

z(mm ) 5 0

5 0

4 0 5 D 2 0 L -m

- • 0 

# 1 w -2 0 ' -4 0 -5 0 0

z(mm ) 4 0 7 D 2 0 0 -2 0 -4 0 

# < | 3 §

-5 0 0

z(mm ) 5 0

5 0

Figur e 4. 7 Experimenta l cross-sectional distribution s o f th e horizonta l ai r velocity (U a x , m/s ) alon g ihe vertiea l pip e alon g th

e vertica l pip e behin d a 90 ° bend (R/D=1.3 , Ris th e ben d radiu s 100m m and D is pip e diameter 75mm ; 0 D i s 10mm away fro m th e ben d outlet) . A s fo r th e radia l ai r

velocit y (U a x ) i n th

e x axis . Figur e 4. 7 an dFigur e 4. 8 respectivel y sho w th e experimental an dnumerica l distribution s o f U a xo n the eight

cross-section s fro m0 D t o 7 D i n th

e vertica l pip e behin dthe 90 ° ben d(R/D=1.3) . I n Figur e 4.7 , the experimenta l cross-sectional

6 1Chapte r4 Kxpcrimenla l studie s ofcross-sectinna l characteristic s o f ai rvelocit y i n pipe s distributio n o f

U a xo n each sectio n ca n b e classifie dint o thre e sub-region s accordin g t o the directio n o f

U a x . Thes e sub-region s includ e th e mi dstri p alon g the x axi s an dtw o sector s outsid e th e strip toward s th

e pip e lef

t andrigh t

walls . Accordin g t

o the colou r

ba r i n Figur e 4.7 , the mixe dcolou r

o f yellow-gree n represent s Ua x clos e t o zero velocity . Th e dar k blu e stand s fo r

the fastes t U a xi n th

e x negativ e directio n an dthe dar k re dindicate s the fastes t U a xi n th

e x positiv e direction . A s such , U a xi s positiv e o r zero i n the mi dstri p an dnegativ e i n th e tw o sectors . A n interestin g phenomeno n i s show n i n th e cross-sectiona l distributio n o f U a xo n th

e sectio n OD , wher e th e positiv e maximu mU a x(3m/s ) locate s o n th e mi dstri p clos e t o the pip e inne r

wal l (th e negativ e x axis ) an dU a xtend s t o b e zer o a

t the pip e outer

wall . In tw o sectors , U ^ change s it s directio n fro mth

e positiv e t

o the negativ e whe n ai r flo w reache s the pip e outer wall . The n U a xi s graduall y accelerate dtoward s th e pip e inne r

sid e til l i t

reache s the maximu mmagnitud e o f U a xi n the negativ e x axi s (-3m/s) . Thi s proces s illustrate s asecondar y flo w resultin g fro mthe momentu mtransfe r

amon g three component s o f ai r velocit y due t

o the 90 ° ben da

t the sectio n OD . Thi s secondar

y flo w include s tw o circulations . Eac h the mstart s fro mth e pip e oute

r wal l (U a x tend s t o b e zero) . The n one i s accelerate dalon g the pip e lef t wal l counter

clockwis e whil e U „ show s an increasin g tendenc y i n th e negativ e x directio n B y contrast , th e other i s accelerate d alon g the pip e righ t

wal l i n th

e negativ e x directio n clockwise . Whe n bot h subflow s mee

t a t th e pip e inner

wall , they ar

e mixe dan dru n toward s the pip e centre (th e positiv e x direction) , U a x reache s it s maximu mpositiv e valu e (dar k re dcolour ) befor e the pip e centre . The n U a xgraduall y decrease s t

o b e nearl y zero i n th

e mi dstri p clos e t

o th e pip e outer

wall . Thes e tw o circulation s demonstrat

e asymmetrica l feature i n th e cross-sectiona l distributio n o f U a x . Perhaps , thi s symmetr y i s due t

o ai r flo w comin g alon g th

e x axi s i n th

e horizonta l pip e an dther e bein g n o additiona l forc e i n the z axis . O n th e downstrea

msection s ID , 2 D an d3D , the cross-sectiona l distribution s o f U a l ica n b e stil l observe dt o b e simila r

t o tha t o n the sectio n OD . Bu t the symmetri c feature o f U a xshow n a

t the sectio n O D i s skewed . Th e regio n wit h th e maximu mpositiv e radia l ai r velocit y (U a x ) shift s from the pip e inner

wal l toward s th

e pip e centre . Compare dwit h tha t o n th e previou s sections , th

e U a x scal e number

i s obviousl y reduce do n the section s from4 D t o 6D . Th e differenc e o f U a xbetween the mi dbelt

an deither

o f th e tw o sector s become s smaller an dth e positiv e pea

k o f U a xdecrease s a s well . However , o n th

e sectio n 7D , the cross-sectiona l distributio n o f U a xshow s tha

t U a xi n th

e mi dbel t become s positiv e agai n an dthe positiv e maximu mU a xoccur s clos e t o th e pip e centre . Thi s i s unexpecte dan ddoe s not agre e wit h thos e o n th e previou s cross-section s du e t o unknow n reasons . Overall , variation s o f cross-sectiona l distribution s o f U a xfro mO

D t o 7 D indicate s tha

t th e ben deffec t

o n th e momentumtransfe r

betwee n th

e axia l ai r

velocit y (U a y ) andthe radial ai r velocit y (U M ) i s stil l activ e a s far a s th e sectio n 7D .

6 2


## VES01709 7A n investigatio n o f particl e dynamic s i n a dilut e phas e pneumati c conveyin g syste m

7 D

6 D

5 D

4 D

3 D

2D 1 D

OD

Contour s o f X Velocit y (m/s ) De c 0 1 , 2 0 0 8 FLUEN T 6. 3 (3d , pbns , ske ) Figur e 4. 8 Numerica l cross-sectiona l distribution s o f th e horizonta l ai rvelocit y (U,„ ) alon g th e vertica l pip e behin d a 90 ° bend (R/D=1.3 , Ri s th e ben d radiu s 100mm an d D i s pip e diamete r 75mm ; OD is 10m m awa y fro m th e ben d outlet) . Figur e 4. 8 show s th

e numerica l distribution s o f U a xo n the section s fro mO

D t o 7D . Compare d wit h Figur e 4.7 , asimila r structure o f

the Ua x cross-sectiona l distributio n ca n be observed , especiall y on th

e sectio n OD . Th e symmetrica l feature alon g the z axi s i s clearl y show n i n th e cross-sectiona l distributio n o f U „ o n eac h section . However , the symmetrica l structure o f the experimenta l datashow n i n Figur e 4. 7 i s no t regula r lik e thos e predicte db y the numerica l datai n Figur e 4.8 . I

n addition , th

e differenc e o f

U a xbetween the mi dstri p an dit s tw o outside s graduall y become s smaller , fo r

the magnitude ofU a xestimate db y the numerica l datadecrease s either i n th e mi dstri p o r

i n the tw o side s o f

th e strip . Consequently , the numerica l predictio n o f th e secondar

y flo w describe db y U a xbecome s weake r an dweake r

fro mth e sectio n 0 D t o 7D . B y contrast , the experimenta l secondar

y flo w show n b y U ^ i s observe dt o retai n alarger

magnitud e o f

th e

6 3


## VES01709 8 J. Q

~> r 2. 0 ] . 5 

# i . a 0. 5 O. Q -fl. 5 

# - i . a -1. 5

- 2 . 

# aI haple r 4 experimenta l studie s o f cross-sectiona l characteristic s o f ai rvelocit y i n pipe s negativ e U a xi n th

e boundar

y ofth e pip e lef

t an dright wall s o n the sectio n 6D .

U /< U > profile

s O n th e x axi s 2. 5 2

v _

_ » 1 i

0 2. 5 6 D U IU profile s On th e z axi s 6D

0.6 1. 2 : 4 D

O l 2. 5

0 2.5 , 4D

2 D

C F D

ID A i

- 1 -O. f O D -0. 2 0. 2 0. 6 x/ R 0. 6 t 1. 2 2 D

0. 6 : 1. 2 0D

C F D LD A

- 1 -0. 6 -0.2 0. 2 0.

6 2/ R Figur e 4. 9 Profile s o f U;, * an d U n >alon g th e x axi s a

tfou r selecte d vertica l cross-section s (<U» > i s th

e mea n absolute valu e o f

U„ ; U nis th

e ai rconveyin g velocit y I Om/s) I n order t o quantitativel y andclearl y compare th e experimenta l datawit h th e numerica l results , the numerica l andexperimental profile s o f U a xan dU a yo n the x axi s andon th e z axi s ar

e displaye di n Figur e 4. 9 an dFigur e 4.1 0 respectively . Figur e 4. 9 show s th

e evolutio n o f

profile s o f

U a xandU a yi n the x axi s a t the fou r selecte dcross sections . With regar

dt o U a x , th e numerica l U a xprofil e shap e i s simila r t o th e experimental one o n eac h section . Bot

h the numerica l an dthe experimental dat asho w tha t U a xi n the negativ e x axi s i s faste r

tha n i n fh e positiv e x axis . Th e widt h o f U a xprofil e graduall y expand s fro m0 D t o

64


## VES01709 9