P. 1 

# OAR Box UIO Prepped by Ryan Dugan



## Document

Number: 

# 2 ) IV-B- 1 Docket Number: 

# A-82-3 9

Printed 4/14/2008 1:23:55PM

Sheet 2 of 156P. 2

% r* * 

### i

* l PRO* 0 

### UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y/

|/-~S^ / Offic e of Ai rQualityPlannin g an d Standard s Researc h Triangl e Park , Nort h Carolin a 2771 1

2 0 

## M t« *
MEMORANDU M SUBJECT : Requiremen t o f Continuou s Opacit yMonitor s (COM's ) i n th e

Caleine r an d Drye r Ne wSourc e Performanc e Standard s (NSPS ) 

# uirHdAiY^i " FROM : Bil l Harnet t iA H IW/TMUV \ C 

### ^ U ^O ^ Standard s Preparatio n Section , SD B (MD-13) ? c 

### tr*>\-^ ° TO : Dou g Bell , Chie f^ \9 % Standard s Preparatio n Section , SDB (MD-13 ) ^$> \ r.\ 

## c r

## - INTRODUCTIO N O n Apri l 23 , 1986 , th e Ne wSource Performanc e Standar d fo r Calciner s an d Dryer s i n Minera l Industrie s wa s propose d i n th e Federa l Registe r (5 1 F R 15438) . T o ensur e prope r operatio n an d maintenanc e o f th e contro l devices , on e aspec t o f th e standar d require s th e us e o f COM' s b ymos t o f th e industrie s affected . Durin g th e publi c commen t period , severa l industrie s commente d tha t th e increase d capita l an d operatin g cost s associate d wit h continuou s opacit ymonitorin g ar e no t commensurat e wit h th e benefits . A s a resul t o f thes e comments , th e CO M requirement s hav e bee n reexamine d fo r al l industries . Thi s memorandu n disucsse d th e assump tion s and analyse s associate d wit h thi s reexamination . BACKGROUN D Th e propose d standar d state s tha t new , modified , an d reconstructe d calciner s an d dryer s mee t emissio n level s o f 0.0 4 gr/dsc f and 0.02 5 gr/dsc f respectively . Th e contro l device s tha t ca n b e use d t o mee t th e emissio n limit s ar e electrostati c precipitators , baghouses , and we t scrubbers . A s proposed , owner s o r operator s o f affecte d facilitie s whic h us e electrostati c precipitator s (ESP's ) an d baghouse s (3H's ) t o compl ywit h th e standard s woul d b e require d t o instal l COM' s t o neasur e and recor d th e opacit yo f emission s fro mth e contro l device . Fo r scrubbers , pressur e dro p and liqui d flo wrat e monitorin g device s wer e required . U e receive d n o negativ e comment s concernin g th e monitorin g requirement s fo r scrubber s and thei r requirement s wil l remai n th e same . Developmen t o f th e propose d CO M provision s wa s base d o n th e followin g analysi s and assumptions : First , a s a matte r o f polic yan d pas t experience , w e assum e tha t COM' s ar e usefu l an d beneficia l an d shoul d b e require d i nP. 3

case s wher e th e cos t i s reasonable . Th e utilit yan d benefit s deriv e bot h fro mEPA' s enhance d enforcemen t abilit yand fro mindustrie s abilit yt o bette r maintai n contro l system s whe n emissio n dat a ar e available . Th e reasonable
nes s o f th e cos t impac t o f th e standar d wa s evaluate d usin g a criterio n o f cos t effectivenes s les s tha n o r equa l t o $3,000/M g ($2,700/ton ) o f particulat e matte r (PM ) removed . A t proposal , t o calculat e th e cos t effectivenes s (CE ) o f installin g and operatin g a COM , th e annua l operatin g cos t o f th e CO M wa s adde d t o th e incrementa l annua l operatin g cos t o f th e P M contro l devic e and the n divide d b

yth e incrementa l emissio n reductio n achieve d b yth e contro l devic e abov e baselin e (Se e Attachmen t 1 fo r example) . Wit h th e exceptio n o f th e fou r proces s unit s liste d below , al l o f th e cos t effectivenes s value s wer e les s tha n o r equa l t o $3,000/Mg . Th e fou r proces s unit s tha t faile d t o mee t thi s criterio n were :

1 . Gypsumflas h calciner s 2 . Gypsu mkettl e calciner s 3 . Perlit e rotar ydryer s 4 . Perlit e expansio n furnace s Th e propose d standar d allow s weekl yvisibl e emissio n reading s a s an alternativ e t o a CO M fo r thes e proces s units . Th e CO M requirement s resultin g fro m th e analysi s describe d abov e prompte d comment s fro msevera l industries , includin g Alumina , Bal l Clay , Fir e Clay , Kaolin , an d Lightweigh t Aggregate . Th e comment s generall y state d tha t th e cost s o f monitorin g device s ar e excessiv e and tha t th e benefits , i f any , ar e smal l and d o no t offse t th e costs . A s a resul t o f thes e comments , th e basi s o f th e propose d CO M requirement s ha s bee n reevaluate d and alternativ e decisio n criteri a hav e bee n investigated . Th e nex t section s present s th e result s o f thi s wor k and a recommendatio n o n ho wt o proceed . ANALYSI S Severa l commenter s o n th e propose d CO M requirement s state d tha t broke n bag s i n a collecto r ar e apparen t withou t th e nee d fo r a CO M and th e increase d capita l and operatin g cost s associate d wit h COM' s d o no t produc e emissio n reductio n benefits . Thes e commenters fel t tha t thi s requiremen t shoul d onl yappl yt o majo r source s o f pollution . I t i s tru e tha t a sudde n increas e i n emission s Troma B H o r ES P woul d indicat e a sudde n failur e o f th e contro l devic e whic h woul d requir e immediat e attentio n b

yth e sourc e operator . However , th e purpos e o f a CO M o r othe r monitorin g alternative s suc h a s dail yvisibl e emission s observation s i s t o aler t th e operato r t o th e nee d fo r maintenanc e t o correc t cause s o f mor e

. * ' * 'P. 4

subtl e an d gradua l deterioratio n o f th e contro l devic e efficienc ytha t occur s ove r time . Withou t COM's , operator s hav e essentiall yn o tool s tha t the yca n us e t o properl yse t up o r optimiz e ESP' s o r fabri c filte r systems , o r t o assum e tha t necessar ymaintenanc e i s performed . Th e ES P rappin g cycles , fabri c filte r cleanin g cycles , broke n rappe r weld s and ba g deter
ioratio n ar e example s o f item s tha t effec t emission s an d tha t canno t b e evaluate d o r detecte d excep t wit h COM' s (Se e Attachmen t 3) . Thes e item s d o no t sho wu p a s catastrophi c failures . Becaus e th e materia l collected
b yth e contro l equipmen t i s a saleabl e produc t i n a numbe r o f th e industrie s covere d b

ythi s NSPS , th e CO M ha s th e benefi t o f savin g mone ya s wel l a s preventin g pollution . Th e reportin g o f excursion s a s recorde d b yCOM' s als o help s Stat e an d loca l enforcemen t program s identif ysource s whic h ar e havin g repeate d maintenanc e problem s wit h thei r contro l devices . However , a s th e amoun t o f emission s fro m a n individua l sourc e decrease, " th e benefit s o f monitorin g als o decreas e an d a t som e poin t i t i s n o longe r reasonabl e t o requir e a CO M o r othe r monitorin g alternative . I n fact , i n th e extrem e cas e o f a smal l fabri c filte r syste mo n a transfe r point , th e cos t o f a CO M coul d excee d th e fabri c filte r cos t bu t becaus e o f th e smal l emissio n benefi t possibl e a s a resul t o f improve d maintenance , th e potentia l benefi t o f th e CO M woul d b e small . A n alternativ e approach t o assessin g th e reasonablenes s o f th e monitorin g requirement s base d onl yo n th e cos t effectivenes s o f th e contro l devic e an d th e monitorin g alternativ e a s wa s don e a t proposa l woul d b e t o conside r othe r factor s i n additio n t o cos t effectivenes s suc h a s th e significanc e o f th e source' s emission s an d th e othe r benefit s o f monitorin g requirement s a s discusse d above . Th e Agenc yha s previousl yaddresse d th e significanc e o f a n emissio n source' s potentia l t o emi t P M i n th e developmen t o f th e preventio n o f significan t deterioratio n (PSD ) o f ai r qualit yprogram . I n th e PS D rules , th e Agenc yse t d e minimi s level s o f emission s fo r variou s pollutants . Fo r P M emissions , th e leve l wa s selecte d b yevaluatin g th e potentia l effec t o f differen t emission s level s o n a n area' s ai r qualit yand ho w tha t relate d t o th e nationa l ambien t ai r qualit ystandar d fo r PM . -Ulg ^ ana l y_s

i ij d ^wa.s_.bA5.ed_jpi ! ...

a _. s o u r x ei s _p.o

t en.tj.al~to„em.i„t_a.f_teii-a p pl i catiojupj C TlT~ap'prbpriAte.J.ederal__re g Th e significanc e leve l ""for ' P M emission s wa s se t a t 22. 7 Mg/y r (2 5 Tons/yr) . Thi s cutof f coul d b e considered i n determinin g whic h facilitie s shoul d b e require d t o instal l COM' s i f the yus e dr ycontro l devices . Fo r calciner s and dryer s wit h emission s o f les s tha n 22. 7 Mg/y r afte r NSP S controls , fou r monitorin g alternative s wer e evaluated : (1 ) installatio n o f a COM ; (2 ) dail yvisibl e emission s observations ; (3 ) weekl yvisibl e emission s observations ; an d (4 ) n o monitorin g requirements . Afte r consideratio n o f th e cost s and othe r benefit s associate d wit h a COM , i t appear s t o b e unreasonabl e t o requir e COM' s o n th e smalle r emissio n source s (i.e. , controlle d emission s < 22.7Mg/yr) . I n lie u o f COM's , w e als o reassesse d th e reasonablenes s o f performin g dail yversu s weekl yvisibl e emissio n observations . W e determine d tha t th e cos t o f eithe r woul d b e simila r bu t woul d no t delive r th e sam e benefit s a sP. 5

th e COM's . I n bot h cases , employee s o f th e affecte d plan t woul d nee d t o b e formall y-certifie d a s opacit yreader s twic e pe r year . Th e cost s associate d wit h th e certificatio n woul d b e incurre d regardles s o f whethe r a dail yo r weekl ymonitorin g requiremen t wa s imposed . Th e othe r cost s associate d wit h thes e alternative s ar e th e annua l cos t o f performin g th e observation s an d recordin g th e results . Th e annua l cos t o f weekl yreading s o f visibl e emission s woul d b e reduce d somewhat , bu t becaus e o f th e fixe d cos t o f certification , woul d cos t approximatel y4 0 percen t o f th e cos t o f doin g dail yobservations . Moreover , a dail yobservatio n progra mwoul d b e mor e effectiv e a t identifyin g gradua l deterioratio n o f th e contro l devic e efficienc yand allowin g a plan t operato r tim e t o correc t th e proble m prio r t o a complet e failur e o f th e device . Aweekl yobservatio n progra m woul d no t identif yth e gradua l deterioratio n o f th e contro l devic e a s quickl yand , i n som e cases , a failur e o f th e contro l devic e coul d occu r betwee n tw o weekl yobservations . Becaus e requirin g dail yobservation s woul d yiel d substantiall ygreate r benefit s tha n weekl yobservation s an d th e cos t differenc e wa s considere d reasonable , th e alternativ e o f weekl y observation s wa s considere d inferio r fo r th e source s wit h les s tha n 22. 7 Mg/y r o f emission s afte r NSP S control . A s i s th e cas e wit h COM's , th e cos t o f doin g dail yvisibl e emissio n observation s doe s no t chang e wit h th e siz e o f th e sourc e o r th e contro l device . Thus , fo r ver ysmal l source s wit h smal l contro l devices , th e cos t associate d wit h dail yvisibl e emissio n observation s ca n b e a significan t portio n o f th e annualize d cos t o f operatin g an d maintainin g th e contro l equipmen t eve n thoug h th e benefit s i n term s o f reducin g exces s emission s hav e decreased . A t som e point , visibl e emissio n monitorin g requirement s ar e n o longe r reasonabl e becaus e th e benefit s ar e smal l bu t th e cos t o f monitorin g ha s substantiall yincrease d a s a percen t o f th e annualized cos t o f th e contro l equipment . T o determin e th e exac t siz e o f a sourc e wher e monitorin g requirement s ar e n o longe r reasonabl e i s mor e a functio n o f judgmen t tha n analysis . Whil e th e cost s ca n b e estimate d wit h reasonabl e certaint yth e actua l reductio n i n exces s emission s tha t woul d occu r i s muc h mor e uncertain . Consideratio n wa s give n t o th e magnitud e o f th e cos t o f dail yvisibl e emissio n observation s a s a percen t o f th e annualize d cos t o f operatin g th e contro l equipment , th e siz e o f th e sourc e i n term s o f th e emission s afte r NSP S contro l i s applied , and th e benefit s associate d wit h monitorin g requirement s suc h a s identifyin g source s wh o ar e havin g contro l equipmen t problem s fo r th e appropriat e enforcemen t agenc ys o correctiv e actio n ca n b e taken . Base d o n a consideratio n o f al l thes e items , w e conclud e i t j s unreasonabl e t o requir e source s wit h les s tha n 1 0 Mg/y r o f particulat e emission s afte r NSP S contro l t o perfor mdail yvisibl e emissio n observations . Th e cos t o f th e dail yobservation s fo r th e mos t o f thes e smal l source s i s mor e tha n 1 0 percen t o f th e annualize d cos t o f operatin g and maintainin g th e contro l device . In addition , th e potentia l benefit s i n term s o f reduce d episode s o f exces s emission s woul d b e muc h smalle r fo r thes e source s tha n fo r th e large r sources . 

# iP. 6

RECOMMENDATION S Becaus e o f th e variatio ninemission s afte r NSP S contro l fo r eac hsiz e andtyp e o f caleine r o r drye r an dfo r eac hindustry , th e monitorin g requirement s shoul db e base donth e typica l siz e o f a particula r typ e o f calcine r o r drye r i neac hindustry . Tabl e 1 show s th e NSP S leve l o f emission s fo r eac htyp e an dsiz e o f calcine r an ddrye r i neac hindustr y andwhic hsize s ar e typica l (se e Attachmen t 2) . I t i s recommende dtha t COM' s b e require donal l dryer s o r calciner s withi na

nindustr y

wher e th e typica l siz e uni t ha s emission s afte r NSP S contro l equa l t o o r abov e 22. 7 Mg/yr . Fo r thos e typica l unit s wit hemission s les s tha n22. 7 Mg/y r bu t greate r tha no r equa l t o 1 0 Mg/yr , i t i s recommende d tha t thes e source s b e require dt o perform dail y visibl e emissio nobservations . Fo r thos e industr y

categorie s wher e th e typica l siz e uni t emit s les s tha n 1 0 Mg/yr , i t i s recommende dtha t no monitorin g requirement s b e place don thes e units . Tabl e 1 contain s a summar y o f th e recommendation s fo r eac h typ e o f drye r an

dcalcine r i neac hindustr y (se e Attachmen t 2) . Attachment sP. 7



### Attachmen t 1

Th e annua l cos t effectivenes s o f contro l obtaine db y meetin g NSP S leve l o f emissions :

Cos t o f transmissomete r + Improve doperation s an d maintenanc e cos t o f contro l devic e C/ E = Incrementa l Emissio nreductio n Example : Bal l cla y

industr y

whic huse s a vibratin g grat e drye r proces s uni t $10,688 * + $5,00 0 C/ E = 3 1 tons/y r - $506/to n
*Note : Sinc e thes e calculation s wer e made , th e labo r rat e ha s

increase dan

dth e annua l cos t o f a continuou s opacit y monito r i s now

$12,800 . 7... Y

•4P. 8

' , ATTACHMEN T 2 TABL E 1 . NSP S EMISSION S AN D MONITORIN G RECOMMENDATION S

Industr y Alumin a
Bal l Cla y
Bentonit e
Diatomit e

Feldspa r
Fir e Cla y

Fuller' s Eart h
Gypsu n

Industria l San d Proces s Uni t

Flas h Calcine r Rotar yCalcine r Rotar yDrye r Vibratin g Grat e Drye r Flui d Be d Drye r Rotar yDrye r Flas h Drye r Rotar yDrye r Rotar yCalcine r Flui d Be d Drye r Rotar yDrye r Rotar yDrye r Vibratin g Grat e Drye r Rotar yCalcine r Flui d Be d Drye r Rotar yDrye r Rotar yCalcine r Rotar yDrye r Flas h Calcine r Kettl e Calcine r Flui d Be d Drye r Rotar yDrye r Desig n NSP S Emission s (Mg/Yr ) fo r variou s size d plant s 

### S

- 

### T 7 

### 4

-

-

- 

### 1 0 T1 2

- 

### 11

-

- 

### 7

- 

### 15

- 

### T 8 

### 9

-

-

- 

### 9 T7 

### M

- 

### 9 1 T g 

### Tl 5 T"2 7

• T l 4

- 

### T 8

- • 

### T 5 

### 8 TlO T 

### 3 3 T 2 

### 5

- 

### 1 2 T 

### 2 3 T7 T 2 

### T l 

### Tl 8 1 2 

### L

T 8 

### 7 11 3

- 

### 3 0

- 

### 2 4 2 1

- T 

### 2 2 T g T l 3 • 

### 1 4

-

- 

### T6 3 1 8 3 0 9 '

-

- 

### 4 2 2 1 

# i Recommendatio n 

### CO M CO M N o Monitorin g Dail yV.E.' s 

### CO M Dail yV.E.' s Dail yV.E.' s N o Monitorin g Dail yV.E.' s N o Monitorin g 

### DailyV.E.' s Dail yV.E.' s 

### CO M CO M CO M N o Monitorin g 

### CO M N o Monitorin g N o Monitorin g N o Monitorin g Dail yV.E.' s N o Monitorin gP. 9

,
Industr y Kaoli n

Lightweigh t Aggregat e Magnesiu m Compound s
Perlit e
Roofin g Granule s Tal c

Titaniu m Dioxid e

Vermiculit e

•i f T = Typica l s i Dail yV.E.' s = ATTACHMEN T 2 (continued )

Proces s Uni t Rotar yDrye r Spra yDrye r Flas h Calcine r Multipl e Heart h Furnac e Rotar yCalcine r Rotar yCalcine r Multipl e Heart h Furnac e Rotar yCalcine r Rotar yDrye r Expansio n Furnac e Flui d Be d Drye r Rotar yDrye r Flas h Drye r Rotar yDrye r Rotar yCalcine r Flas h Drye r Flui d Be d Drye r Rotar yDrye r Rotar yDrye r (Ind i rect ) Spra yDrye r Rotar yCalcine r Flui d Be d Drye r Rotar yDrye r Expansio n Furnac e Desig n NSP S Emissi c fo r variou s size d 

### S

-

- 

### T 2 

### 6 T 7 

### Tl 8 3 4 11
T 

### 3 0

- 

### T 4


### Tl 4 T 4

- 

### Tl 5

- 

### 1

- 

### 6 2 7

-

- T 4 

# 1 M

T 9 Tlf i

-

-

- T 

### 4 9 T3 5 4 3 

### Tl 5

- Tl 3 T2 2

- 

### T 5

- ; 3 

### T l 

### Tl 5 T5 3

- 

## Tn 

# 1 ze ; - = Dat a i s no t available ; CO M = Co n Dail yvisibl e emissio n observatio n HI S (Mg/Yr ) plant s 

### L

- 

### T 2 

### 6

-

-

- 

### 6 6 

### T4 9

- 

### 25^

-


### 2 9

- 

### 19

- T 2 8 Tl 8 

### T 7

- 

### 2 4

- 

### Tl 9 1 2

- tinuou s Opa < Recommendatio n

N o Monitorin g 

### CO M CO M N o Monitorin g Dail yV.E.' s 

### CO M CO M CO M Dail yV.E.' s No - Monitorin g Dail yV.E.' s Dail yV.E.' s No . Monitorin g N o Monitorin g Dail yV.E.' s CO M Dail yV.E.' s N d Monitorin g N o Monitorin g Dail yV.E.' s 

### CO M Dail yV.E.' s Dail yV.E.' s N o Monitorin g :it yMonitor ;P.1 0 

### ATTACHMEN T 3



# PUUWN G Opacity monitorin g o

fstac k emissions : A desig n too l wit h promisin g result s

Reprintedfro m th e electri cutilit y. . . GENERATIO N PLANBOO K197 4 (B yth e editor s o f Powe rmagazine ) Copyrigh t McGraw-Hill , 197 4P.1 1

Montou rStation , whic h wen t o n lin e las t fal l wit h tw o 800-M W coa l lire d units , wa s th e scen e o f PP&L' s opacity-monitorin g installatio n an d revealin g test s Opacit ymonito ri s place d clos e t o precipitato routlets . Saving s i n tim e an d cos t sho wtha t breechin g an d duc t i n tim e an d cos t sho wtha t breechin g an d ductwor k ar e th e mos t satisfactor ylocation s



# Opacit ymonitorin g o f stac k emissions : Adesig n too l wit h promisin g result s Ho wca n th e designe rmak e plan s fo revaluatin g performanc e o f a n electrostati c precipitator ? I s i t a t al l possibl e t o 'tune ' a precipitato rfo roptimu m performance ? A t leas t on e utilit ybelieve s the yhav e foun d a feasibl e metho d o f optimizin g precipitato rperformanc e throug h continuou s opacit yreading s B y W A Schneider , Plan t Bettermen t Fiel d Assistant , Pennsylvani a Powe r& Ligh t C o Gaugin g precipitato r

performanc e i nyear s pas t wa s generall y ajo b o f

physica l tes t

for efficiency , o r

for out le tgrai nloading . Thi s scheme , a t best , provide da nav erag e figure relate dt o severa l hour s o f operation . Dus t testin g call s for

severa l me nan dconsiderabl e tim e t o yiel dthi s information . Ye t throug hreal-tim e observa
tio no f th e effect s o f

precipitato r

contro l changes , fue l changes , an dchange s in boile r operatin g condition s o n outle t dus t loading—al l throug hus e o f continuou s opac ity monitoring- areasonabl e appraisa l o f performanc e ca nb e made . An dfro ma noperatin g standpoint , shoul d a nexistin g precipitato r fal l shor t

o ncollectio nability , opacit y monitorin g wil l ope nth e doo r t o availabl e al
ternative* . Th e alternative s ope nt o th e designcr-an dpost designer—ar e many . Th e searc hthe nboil s dow nt o a practica l mean s for

accuratel y evaluatin g thes e alterna
tives . I nbrief

, th e possibl e alternat e path s encompas s optimization of

.existing precipitator

. . . updating . . . modifying boiler

operating conditions . . . changing flue gas resistivity. . ^bringing in additional collection equipment. It wa s the^earc hthroug hthes e alternative s tha t le d t o th e opacit y monitor . Opacit y monito rconsist s o f aligh t source , an da photocel l arrange ds o th e ligh t mus t pas s throug hth e ga s strea mprio r t o bein g measure db y th e photocell . Chang e inligh t

absorptio ncause db y particulate s i nth e ga s i s ameasur e ofth e quantit y o f dus t passin g betwee n sourc e an dphotocell . W e weren' t

int o ou r

opacity-testin g progra mlon g whe nw e foun dth e valu e i ndetectin g effect s o f individ
ua l rappers , o r

smal t change s i nprecipitato r powe r lev
els , a s bein g mos t

importan t

i nevaluatin g an doptimiz
in g performance . I nth e Lcar-Siegle r RM- 4 opacity
testin g equipmen t

w e used , th e photocel l an dligh t sourc e ar e locate di nth e sam e housin g o non e sid e o f th e ga s stream , wit hareflecto r o nth e other . Thi s mean s tha t th e light-pat hlengti i i s a t leas t doubl e th e widt ho f th e ga s passage , enhancin g th e monitor' s sensitivity . Selectio nofth e syste mwa s base do nit s us e o f visibl e wavelengths , sinc e accurac y o f detectin g submicro npar ticle s i s poo r

wit hinfrared . Moreover , it output s asigna l for optica l density . A s thi s i s proportiona l t o outle t grai n loading , it

provide s avaluabl e featur e whe ncombine d wit hhig hsensitivity . Accurac y playe d amajo rrol e inou r monito r selec
tion . On e facto r

wa s th e monitor' s desig nfeatur e o f a singl e locatio nfor

bot hligh t

sourc e an ddetector . Thi s featur e mean s tha t

th e uni t ca nb e checke dinservic e fo r zer o an dspa ncalibration , l neffect , it automaticall yP.1 2 

# U^im

Cow voltage, tittle sparking, large rapping effects Medium voltage, moderate

sparking, small rapping effects High

voltage, heavy sparking, moderate

rapping

effects Effect s o f voltag s contro l change

s at constant rappin g Intensit

y 10 0
Optical-densit y recor d show s interactio n betwee n precipitato r voltag e an d rappin g intensity . Tw o monitor s wer e use d fo r increase d detectio n o f performanc e change s 4 0 6 0 Opacity , % i i i I i__ i I I i I I 10 0 6 0 6 Q 4 0 2 0 0

Tra«smlttoii««,*/

* Relationshi p betwee n optica l densit y a s measure d an d opacit y o r transmittanc e check s an doutput s zer o an dspanvalue s periodically . Adjustment s canb e mad e fo r dus t buildu p o nth e win
dows , o r becaus e o f

bulb-intensity decay , whil e th e in
strumen t i s o nline . Befor e developin g an dusin g opacity-monitorin g equipment , tw o progra mstep s mus t b e considered . Firs t i s examinatio no f

th e precipitato r

maintenanc e an dop eratio ndata . Th e secon di s t o combin e thes e dat awit h a ninspectio nb y th e manufacturer . Earl y identificatio n o f problems

—particularl y i nalignmen t stabilization , leakage , ga s distribution—can b e o f considerabl e value . W e foun dtha t

suc hsmal l bu t

importan t

modification s contribute dimmensel y t o improve dreliability . Nex tmov e bring s th e opacity-monitorin g equipmen t fc int o th e act . A s inan y dus t test , yo u mus t

identif y an d contro l al l variable s know nt o affec t precipitato r

per formance . I nou r

evaluation , we foun dth e following mos t significant : Fue l resistivit y an das hcontent ; boiler load : boiler

outlet-ga s temperature ; boile r excess-air l=-d . precipitato r

operatin g voltage ; precipitato r rap pi.-. 2 intensit

y an dprogramming ; an dprecipitato r inter
nal conditions . Eac ho f

thes e area s canb e studie dwit h opacity-monitorin g equipment . Th e designer shoul d bea r inmin dtha t

th e determinatio no f

th e "propor
tionality constant " betwee noptical density an doutle t grai nloadin g canb e determine dthroug hdus t testin g unde r constan t boile r an dprecipitato r

condition s wit

h variou s fuels . Ther e will b e some overlappin g o r interactio no f

vari
ables . Example : precipitato r voltag e an drappin g at

dif
feren t fue l sulfur levels . I t

i s ou r experienc e tha t

fuel sulfu r conten t i s th e on e variabl e where ther e canb e littl e practical control . Thus , al l othe r controllabl e vari
able s must,b e examine dwit hrespec t t o th e fuel' s sulfur content . Afte

r abrie f investigatio no f

th e sulfur

conten t i nth e fuel burned , w

e foun dthat—dependin g o nth e ra n H e o f sulfur content—it

wa s possibl e t o selec t

several subdivision s for

describin g th e effec

t o f eac hvariabl e a t variou s sulfur levels : lo w sulfu r

(les s tha n2%) , mediu m sulfur (2-3%) , an dhighsulfu r

(abov e 3%) . Fue l resistivity , whichi s inversel y relate dt o fuel sul
fu r content , i s abas e for

evaluatio no f

all othe r vari
ables . I t i s valuable l o defin e th e effect o f eac hvariabl e withrespec t

t o fuel sulfur , sinc e estimate s o f percen t o f fuel burne dineac hrang e shoul db e availabl e indefin
in g th e require dus e o f

eac halternative . A cas e in point : th e estimate drequiremen t o f agas-conditionin g agent . Sinc e fuel-sulfu

r increase s represen t

asimulatio no f conditioning , th e fuel sulfur require dt o mee

t regulatio n ca nb e correlate dwit

hconditioning-agen t

quantit y re quirements . B y holdin g al l othe r

variable s constant , acurv e o f fuel sulfur

v s outle t grai nloadin g wa s developed . Re
sult s indicat e that , for

mos t coal s belo w 2 % sulfur , w e di dno t mee t ou r emissio nstandards . Therefore , condi
tionin g agen t

i s injecte dt o matc hth e resistivit y o f27csulfur fuel . Th e special stud y o f

sulfur o r resistivit y effects als o provide s th e mos t

helpfu l informatio nif

additiona l col
lectio nequipmen t

shoul db e required . I f

hig hresistivit

y i s th e major

problem , th e baghous e o r particulat e scrub
be r i s th e mor e logical approach . Conversely , if hig has h level s at low resistivit

y ar e overloadin g th e existin g pre cipitator , th e problem s o f aci dsmu t

o r slurr y p H may eliminat e th e baghous e o r scrubber . Boile rload . O f

primary importanc e here i s th e re ductio n o f

loa dnecessar

y fo r complianc e wit

hfederal o r local particulate-emissio n legislation . A s th e monito r give s asigna l proportiona l t o outle t grai nloading , thi s outpu t canb e correlate dto th e emissio nrat e in pound s pe r millio nBtu . On e mus t

b e careful , however , t o real
iz e tha t th e proportionality factor betwee nIb/c u f

t an d lb/MBt u depend s onth e boiler operatin g condition s an dload . We fee l tha t th e determinatio no f

th e loadreductio n require dfor

complianc e i s valuabl e onl y i nemergenc yP.1 3 

# ^ * 

# i\i x h^ w 

## r

*

Monito r ductwor k

locatio n ca n eas e Installatio n 0. 9 0. 8 0. 7 0. 6 | 0. 5 I 0. 4 I 0. 3 S 0. 2 0. 1 ^&\ I I 1— : 1 : 0.0 5 0.1 0 0.1 5 0.2 0 0.2 5 0.3 0 0.3 5 Groins/c u f

t Testdc'. a relat e optica l densit y t o outle t grai n loadin g

1

-

- ~ 

### 1 j-«— AllowoU e emission rate l l I I I I i I l 

# \P <aP, , 

## %^s

i i y^o

• <^ o

I

0.0 5 0.1 0 0.1 5 0.2 0 0.2 5 0.3 0 0.35

Grolns/cu ft Fue l s•.•"u r v

s grai n loading , othe r variable s constan t
situa: ' .*ns . prio r

t o th e time that

continuou s complianc e i s ach.-:ved . A > ;a s temperature s i

nacold-en dprecipitato r ar e drop:.. ! belo w 32 0 F . precipitato r performanc e im
prov e I t is th e magnitud e of

thi s increase , plu s th e an licipa-.-.-dutilization , whichwouldthe nb e weighed agair . • . probabl e increase dmaintenanc e costs . Exces s air . Wit

hlowere dexcess-air

levels , ga s velo
citie s * • ithi nth e precipitato r

wil l b e lowered , agai nre suhir. . i nincrease dcollection . Althoug hno t nearly s o feas:'-.••-• as lowerin g outlet-ga s temperature , thi s coul d b e \-<-7. i

nemergency . Th e tradeof f of increase dcollec
tio n \- boiler

reliabilit y is nearly identical l o th e al
tern..* . . e o f

outlet-ga s temperatur e reduction . Precipitato r

operatin g voltage . Ou r experienc e shov
- thi s to b e anare awher e muc hinformatio ncan b e realized . B y adjustin g th e control s an dobservin g thei r effects directl y o nth e monito r output , th e bes t manua l operatin g mod e canb e establishe dfo r eachfue l sulfu r level . Afte

r thi s manua l adjustment , precipitato r performanc e canb e compare dt o th e normal automati c operatin g mod e ofth e controlle r fo r evaluation . Magnitud e o f

th e increase dcollectio ngaine dthroug h th e manua l optimizatio nadjustmen t will b e adetermin
in g factor a s t o whethe r

ne w o r improve dcontrol s o r

re distributio no f

power shoul db e considered . W e ob
serve dadecreas e inoptical densit y resultin g fro

msmal l change s incontro l setpoints . I t i s importan t

t o recogniz e a t

thi s tim e that

voltag e levels , rappin g an dparticl e resistivit y (relate dt o fue

l sulfu r level ) ar e al l interactin g variables . Th e approac h t o thei r study mus t

includ e different

combination s unti l th e "optimum " i s discovered . Thi s i s no t a novernight process ; i t

i s greatl y simplified , however , becaus e ofth e real-tim e outpu t

o f th e effects o f

eac hchang e by opac ity-monitorin g equipment . Precipitato rrapping . Th e opacity monito r i s sensi
tiv e enoug ht o detec t

individual rappers , an dtherefore t o locat e th e proble marea s specifically . Th e effect s o f rapping , basicall y o ndus t thicknes s o nth e plate s an d o nre-entrainment , ar e observe dby change s inoveral l optica l densit

y level an dspikes . Unfortunately , th e cur ren t technolog y o f

precipitato r

desig ndoe s not

includ e self-adjustin g rappers , an dtherefore on e migh t consider dail y "tuning " base do noutle t loadin g a s analternativ e for continuou s increase dperformance . Internal condition . Fro mastud y o f th e effect

s o f •eac hof th e above , certai narea s o f th e precipitato r

ma y see mt o respon dmuc hbette r tha nother s i

nattainin g define d"optimum " operatin g conditions . Thi s i s a stron g indicatio no f

interna l physical difficulties . If thi s indicatio ni s further

supporte db y maintenanc e record s o r th e manufacturers' inspectio ncomments , th e indica
tio nof aproble mi s further strengthened . Th e ke y t o obtainin g useful informatio nfo r designer an doperator , fro

maserie s of

test s a s describe dhere , i s t o hol dall parameter s othe r thantha t

bein g investi
gate da s nearl y constan t

an dclos e t o representativ e op eratin g condition s a s possible . I f thi s i s done , ahighly detaile dan dinformativ e picture of th e performanc e o f you r precipitato r

an dth e feasibilit

y o f you r alternative s canb e obtaine di

nroughl y on e month' s time . If evaluate dcarefully , th e following question s ca nb e accuratel y answered : CanI meet m y emissionstandar d wit hm y existin g precipitator ? I s ther e amodificationo f control s or

rapper s tha t

wil l allo w m e to comply ? Are change s i nboiler condition s or

reductio no

f loa dfea
sibl e solutions ? Ca nflue-ga s conditionin g solv e m y problem ? How muc hadditiona l collectio ncapabilit y d o I need , an dwhat

typ e wil l solv e m y problem ? Th e burde no f

meetin g specific particulate-emissio n regulation s by"-197 5 i s alarg e one . Th e investment o f tim e an dmoney wil

l als o b e large . W

e a t PP& Lfeel , however , that

accurat e evaluatio no f

th e problem , in
cludin g th e existin g precipitator , i s amost importan t first step . Th e us e o f

opacity-monitorin g equipmen t ha s enable du s t o develo p aprogra mthat canb e quickly administered , an dcanprovid e accurat e answer s to man y ofth e question s inheren t i nth e selectio n o

f th e bes t alternativ e fo

r increasin g dus t

collection . •