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# OAR Box 1870
Prepped by Ollie Stewart



### Document

Number:

Docket Number: 

# A-90-1 7

Printed 11/28/20087:05:05AM 

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Sheet 46 of 67P. 2 

# A-90-1 9 ll-A-2 9



# m

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CORPORATIO NP. 3

EPA Contrac t No . 68-02-437 8 ES D No . 83/1 8 Wor k Assignmen t 2 0

CARBO N ADSORPTIO N

FORCONTRO L O F VO C EMISSIONS : THEOR YAN D FUL L SCAL E SYSTE M PERFORMANC E

FINAL REPOR T

Prepare dfor : Kare nCatlet t - Wor k Assignmen t Manage r Chemical s an

d Petroleu

m Branc h Emissio nStandard s Divisio n Offic e o f Ai r Qualit y Plannin g an

dStandard s U . S . Environmenta l Protectio nAgenc y Researc hTriangl e Park , Nort hCarolin a 2771 1

Prepare dby : K . W . Barnet t P . A . Ma y J . A . Elliot t Radia nCorporatio n 320 0 E . Chape l Hil l Road/Nelso nHwy .

P.O . Bo x1300 0 Researc hTriangl e Park , Nort hCarolin a 2770 9

Jun e 6 , 198 8P. 4

TABL E O F CONTENT S Sectio nPag e 1 INTRODUCTIO N

1- 1 2 SUMMAR

YAND CONCLUSION S 2- 1 3 THEOR YAN D PERFORMANC E O F CONVENTIONA L FIXE D BE D CARBO N ADSORBER S 3- 1 3. 1 Mechanis m

o f Adsorptio nan

d Desorptio n3- 1 3. 2 Ful l Scal e Adsorptio nSystem s 3-1 3 3.2. 1 System

Overvie w

3-1 3 3.2. 2 Ful l Scal e System Desig nConsideration s 3-1 5 3. 3 Carbo nAdsorbe r Long - an d Short-Term

Efficienc y

3-2 2 3.3. 1 Calculatio no f Carbo nAdsorbe r Efficienc y 3-2 3 3.3. 2 Variabilit y

o f Short-Term

Remova l Efficienc y

3-2 5 3.3. 3 Relationshi p o f Outle t Concentratio nan d Efficienc y

3-2 5 3. 4 Effec t o f Operatin g Variable s onAdsorbe r Performanc e 3-2 9 3.4. 1 Temperatur e 3-2 9 3.4. 2 Concentratio n3-3 3 3.4. 3 Humidit y

3-3 4 3.4. 4 Vo l umetr i c F

l owrat e 3-3 8 3.4. 5 Bed Foulin g 3-4 1 3.4. 6 Channelin g 3-4 3 3. 5 Deliberat e Change s fro m Initia l Desig n Operatin g Condition s 3-4 3 3.5. 1 Adsorbat e 3-4 5 3.5. 2 Steamin g Condition s 3-4 5 3. 6 Performanc e Informatio nonIndustria l Adsorber s 3-4 6 3.6. 1 Dat a Source s 3-4 7 3.6. 2 Remova l Efficienc y Dat a fo r Performanc e Tes t 3-5 2 3.6. 3 Continuou s Remova l Efficienc y Dat a 3-5 7 3. 7 Conclusion s Regardin g Carbo nAdsorbe r Performanc e 3-6 0



### nP. 5



### TABL E OF CONTENTS , Continue d Sectio nPag e
4 CARBON

ADSORPTION

SYSTEM A T COMMENTER' S FACILIT Y4- 1 5 REFERENCE S 5- 1

mP. 6

LIS T O F TABLE S Table s Pag e 3- 1 Reporte d Bed Live s fo r Variou s Solven t Blend s 3-4 4 3- 2 Performanc e Tes t Dat a fo r Carbo nAdsorptio nSystem s 3-4 8 3- 3 Performanc e Tes t Dat a fo r Carbo nAdsorptio nSystem s o na Pe r Be d Bas i s 3-5 0

i vP. 7

LIS T O F FIGURE S Figur e Pag e 3- 1 Representatio no f Carbo nPellets/Particle s i nCarbo nBed3- 3 3- 2 Representatio no f Pore s i nActivate dCarbo nParticl e 3- 4 3- 3 Mechanis m

o f Adsorptio n3- 6 3- 4 Simplifie dRepresentatio no f Carbo nCapacit y 3- 8 3- 5 Availabl e Workin g Capacit y a s a Functio no f Distanc e Throug hBe dfo r a

nOperatin g Be d 3- 9 3- 6 Simplifie dPor e Representatio no f Capacit y a s a Functio n o f Distanc e Throug hBe d 3-1 1 3- 7 Vapo r strea

m Concentratio na s a Functio no f Distanc e Throug hBe d3-1 2 3- 8 Carbo nAdsorbe r System Proces s Flow

Diagram 3-1 4 3- 9 Steam

Consumptio nVersu s Workin g Capacitie s 3-1 8 3-1 0 Adsorbat e Concentratio ni nBe dAfte r Steamin g Countercurrentl y

a s a Functio no f Distanc e Throug hBed.. . 3-1 9 3-1 1 Adsorption/Desorptio nCycle s ina 2 Be dSystem 3-2 1 3-1 2 Determinatio no f Carbo nAdsorbe r Remova l Efficienc y 3-2 4 3-1 3 Typica l Carbo nAdsorptio nBreakthroug hCurv e 3-2 6 3-1 4 Carbo nCapacit y vs . Temperatur e a t Constan t Pressur e 3-3 1 3-1 5 Carbo nAdsorbe r Remova l Efficienc y wit hVaryin g Be d Temperatur e fo r a Complet e Adsorptio nCycl e 3-3 2 3-1 6 GT RTes t Numbe r 6 Continuou s Inlet/Outle t VO C Concentratio n Dat a an dRemova l Efficienc y

3-3 5 3-1 7 GT RTes t Numbe r 5 Continuou s Inlet/Outle t VO C Concentratio n Dat a an dRemova l Efficienc y 3-3 6 3-1 8 Effec t o f Relativ e Humidit y o nWorkin g Capacit y

3-3 7 3-1 9 Effec t o f Variatio ninVolumetri c Flowrat e o nth e Shap e o f th e Breakthroug hCurv e 3-3 9P. 8

LIS T O F FIGURES , Continue d Figur e Pag e 3-2 0 Carbo nAdsorbe r Remova l Efficienc y wit hVaryin g Flowrat e fo r a Complet e Adsorptio nCycl e 3-4 0 3-2 1 Carbo nAdsorbe r Remova l Efficienc y a s a Functio no f Bed Ag e fo r a Keton e Containin g System 3-4 2 3-2 2 Inlet/Outle t Concentratio nCurv e fo r Tes t 3 3-5 4 3-2 3 GT RTes t Numbe r 5 Continuou s Inlet/Outle t VO C Concentratio n Dat a an d Remova l Efficienc y 3-5 8 3-2 4 GT RTes t Numbe r 6 Continuou s Inlet/Outle t VO C Concentratio n Dat a an d Remova l Efficienc y 3-5 9 3-25 a Inle t an

d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 1 3-6 1 3-25 bInstantaneou s an d Cumulative Efficienc y Versu s Cycl e Time fo r Adsorbe r # 1 3-6 1 3-25 c Inle t an

d Outle t Concentratio nVersu s Cycl e Tim e fo r Adsorbe r # 2 3-6 2 3-25 d Instantaneou s an d Cumulative Efficienc y Versu s Cycl e Time fo r Adsorbe r # 2 3-6 2 3-25 e Inle t an

d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 3 3-6 3 3-25 f Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Time fo r Adsorbe r # 3 3-6 3 3-25 g Inle t an

d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 4 3-6 4 3-25 hInstantaneou s an d Cumulative Efficienc y Versu s Cycl e Time fo r Adsorbe r # 4 3-6 4 3-25 i Inle t an

d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 5 3-6 5 3-25 j Instantaneou s an d Cumulative Efficienc y Versu s Cycl e Time fo r Adsorbe r # 5 3-6 5

v iP. 9

LIS T O F FIGURES , Continue d Figur e Pag e 3-25 k Inle t an

d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 6 3-6 6 3-25 1 Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Time fo r Adsorbe r # 6 3-6 6



### v nP.1 0

1 . INTRODUCTIO N

Thi s repor t present s th e result s o f a ninvestigatio nint o th e performanc e an doperatio no f vapo r phas e carbo nadsorptionsystems . Thi s investigatio n wa s initiate da s a resul t o f comment s receive db y th e U . S . Environmenta l Protectio nAgenc y

(EPA) . Thes e comment s wer e inreferenc e t o th e draf t ne w sourc e performanc e standard s (NSPS ) fo r contro l o f VO C emission s fro m the manufactur e o f magneti c tape . Th e commente r challenge dEPA' s supportin g dat a fo r th e propose dperformanc e requirement s fo r carbo nadsorptio nsystem s an d th e cost s fo r operatin g an dmaintainin g carbo nadsorptio nsystem s a t th e require dperformanc e level . Specifically , th e commente r contende dtha t th e 9 5 percent efficienc y requiremen t i s no t achievabl e ona continuou s basi s du e t o th e inheren t variabilit y o f carbo nadsorptio nsystems . The y als o state d tha t ketones , whic har e commonl y use dsolvent s inmagneti c tap e manufacture , reduc e th e performanc e o f carbo nadsorber s an dincreas e system

variabilit y

an d shorte nbe dlif e whic hincrease s th e cos t o f usin g carbo nadsorption . I norde r t o respon dt o thes e comments , th e EPA requeste dadditiona l informatio nfro

m manufacturer s an

duser s o f carbo nadsorbe r system s t o furthe r investigat e system

performanc e an

dcosts . Th e EPA

als o agai nreviewe d informatio nobtaine dfro m previou s studie s b

y th e Agency . Thi s repor t summarize s th e result s o f thi s study . Thi s repor t i s organize da s follows . Sectio n2 present s th e conclusion s o f thi s study . Sectio n3 present s a descriptio no f th e vapo r phas e adsorptio n process , discusse s impact s o f change s ininle t ven t stream characteristic s o

n adsorbe r performance , an dpresent s supportin g tes t data . Sectio n4 present s a descriptio no f th e carbo nadsorbe r system whic hth e commente r use da s a basi s fo r developin g thei r comments , an da discussio no f th e desig nan doperatio no f tha t system .



### 1- 1P.1 1

2 . SUMMARYAN D CONCLUSION S

Thi s repor t wa s specificall y designe dt o addres s comment s submitte d concernin g th e propose dnew sourc e performanc e standard s fo r magneti c tap e manufacture . Thes e comment s ma y b e summarize da s follows : § On e commente r questione dwhethe r an y supporting dat a exis t fo r th e Agency' s positio ntha t 9 5 percen t VO C remova l efficienc y ca nbe achieve dcontinuousl y b y carbo nadsorptio nsystem s ove r al l averagin g periods , includin g short-term periods . Th e commente r submitte dinformatio nindicatin g tha t 24-hou r average s o f efficienc y o f hi s adsorptio nsystem var y dramaticall y

fro m da y t o day . Day s whe nth e averag e efficienc y wa s abov e 9 5 percen t wer e followe d quickl y b y day s wit ha

naverag e efficienc y

o f les s tha n9 0 percent . I t wa s thi s informatio ntha t cause d th e commente r t o questio nth e Agency' s decisio nt o determin e complianc e an dasses s adsorbe r operatio nan

dmaintenanc e base d onshort-term measurement s o f adsorbe r performance .

• Th e same commente r als o state dtha t th e evaluatio no f carbo n adsorptio nt o contro l VO C emission s ha s no t adequatel y addresse dth e problem s associate dwit hth e us e o f ketone s b y th e magneti c tap e industry . Th e commente r submitte ddat a that , i nth e commenter' s opinion , demonstrate dreduce d adsorbe r efficienc y cause db

y th e us e o f ketones . Th e commente r als o implie d tha t th e variabilit y i n carbo nadsorbe r performanc e i s greate r whe nketone s ar e presen t i n th e solven t lade nai r stream an d tha t ketone s shorte nth e usefu l lif e o f th e carbo ni nadsorptio nsystems , resultin g ingreate r cos t impact s attributabl e t o th e NSP S tha nindicate d b y th e cos t analysi s carrie dou t b

y EPA prio r t o proposal . Inorde r t o addres s thes e comments , informatio nwa s requeste dfro m a numbe r o f sources . Thes e include dbot hmagneti c tap e manufacturer s an dothe r type s o f coatin g operation s usin g carbo nadsorber s t o contro l VO C emissions . A meetin g wa s als o hel dwit hrepresentative s o f a majo r supplie r o f activate d carbo nt o obtai nthei r perspectiv e onprope r adsorbe r system desig nan

d operatio nbase do nthei r lon g term experienc e i nthi s field . Inaddition , tw o site s wer e visite dt o obtai nfirs t handinformatio nonth e operatio no f carbo n adsorbe r systems . Emissio ntes t dat a from 1 5 test s performe dfo r th e Emissio n Standard s Divisio no f EPA an dth e Offic e o f Researc han d Developmen t wer e als o reviewe dt o provid e additiona l substantiatio no f adsorbe r performanc e an dt o attemp t t o compar e long - an dshort-ter m

remova l efficiency .



### 2- 1P.1 2

Base donth e dat a collecte dfo r thi s study , th e followin g conclusion s hav e bee nmade .

• Whe nth e carbo nadsorbe r system i s properl y

designe dan

d operated , th e adsorption/desorptio nproces s i s predictabl e an d reproducibl e fro m cycl e t o cycle . t Fo r wel l designe dan doperate dcarbo nadsorbe r systems , continuou s VO C remova l efficiencie s o f ove r 9 5 percen t ar e achievabl e ove r long - an dshort-term

period s fo r a variet y o f solvents , includin g mixture s tha t contai nketone s suc ha s methy l ethy l keton e (MEK ) an d cyclohexanone . Severa l plant s hav e bee nshow nt o continuousl y achiev e remova l efficiencie s o f 97-9 9 percent .

• Al l facilitie s identifie db y thi s study

whic hhadremova l efficiencie s belo w

9 5 percen t hadidentifiabl e operationa l problem s whic hcontribute dt o thei r poo r performance . Al l o f th e operationa l problem s identifie dwer e correctable .

• A carbo nadsorptio nsystem mus t b e designe dbase donth e followin g proces s parameters : 1 ) particula r solvent o r solvent blendbein g recovered , 2 ) solven t load , 3 ) ven t stream flowrate , an

d4 ) ven t stream temperature . Assumin g th e initia l desig nprovide s sufficien t capacit y t o accoun t fo r norma l dail y proces s variation s an dth e adsorbe r i s properl y

operated , th e performanc e o f a carbo nadsorbe r system wil l b e essentiall y constan t fro

m cycl e t o cycle , an

d long-ter m

an dshort-term

efficienc y

wil l b e th e same .

• I f a carbo nadsorbe r be di s lef t on-lin e afte r breakthrough , adsorbe r efficienc y

wil l b e significantl y reduce dan

dma y als o becom e muc hmor e variable . A ke y t o maintainin g highcontinuou s remova l efficiencie s i s t o detec t breakthroug han dbrin g a fres hbed on-line . Ther e shoul dalway s b e a fres hbe davailabl e i f th e syste m i s properl y

designe dan

d operated .

• Becaus e continuou s hig hremova l efficienc y ca nb e achieve d b

y a properl y designe dan

doperate dcarbo nadsorbe r system , short-term performanc e testin g an dmonitorin g requirement s ar e appropriat e a s lon g a s th e complet e system cycl e i s include dinth e tes t o r monitorin g period . t A consensu s o f carbo nsuppliers , carbo nadsorptio nsystem vendors , an dcarbo nadsorptio nsystem operator s indicate s tha t whe n cyclohexanon e i s adsorbed , i t exothermall y react s o

nth e carbo n surfac e t o for

m highe r molecula r weigh t product s whic hcanno t be remove db

y norma l stea

m desorption . Th e subsequen t buil du po f thes e compound s result s ina steady decreas e inth e adsorptiv e capacit y o f th e carbon . Thi s los s inadsorptiv e capacit y decrease s th e tim e whic ha carbo nbe dca nremai non-lin e befor e breakthroug h occurs . Whe nth e adsorptio ncycl e time approache s th e time require d



### 2- 2P.1 3

fo r off-lin e be dregeneratio nan dprope r coo l down , th e carbo nmus t b e replaced . I f th e carbo ni s no t replace dth e poin t wil l be reache dwher e th e operato r wil l b e force dt o either : 1 ) leav e th e bedon-lin e pas t breakthroug hinorde r t o properl y regenerat e th e off-lin e be do r 2 ) switc ht o th e regeneratin g be dbefor e i t ha s bee n adequatel y

steame dan

d cooled . Th e resul t ineithe r cas e wil l be a dramati c dro pi nremova l efficiency . Th e carbo nadsorbe r system o f whic hth e commente r reporte d a s havin g highl y variabl e an

dfrequentl y

lo w remova l efficiencie s i s significantl y

under-designe dfo r th e actua l solven t loadin g i t i s require dt o control . Thi s result s i nth e system bein g operate da significan t portio no f th e tim e afte r breakthroug hha s occurred . A s a result , th e efficienc y o f thi s system

i s extremel y

sensitiv e t o variation s i nth e proces s condition s an dtherefor e exhibit s significan t variation s i nefficienc y from day-to-da y

an d cycl e t o cycle . Th e variation s als o resul t i nsignificantl y reduce d long-term

efficiency . I f th e system wa s operate dwithi nth e desig n limits , the nth e reduce d efficienc y an defficienc y

variatio nshoul d no t occur . A s a carbo nbe dage s an dit s tota l adsorptiv e capacit y graduall y decrease s du e t o fouling , th e workin g capacit y ca ni nsome case s b e maintaine da t th e desire dleve l b y increasing th e stea m flow durin g desorption . Thi s wil l increas e steam costs . Th e decisio no f whethe r t o us e highe r stea m flow o r replac e th e carbo ni s base do n th e cos t o f additiona l steam versu s th e cos t o f ne w carbon . A ke y paramete r t o maintainin g continuousl y hig hremova l efficienc y i s replacin g th e carbo nwel l befor e foulin g reduce s th e adsorptiv e capcity . Mor e frequen t carbo nreplacemen t result s inhighe r annualize dcarbo ncosts , bu t als o prevent s reachin g th e poin t wher e th e adsorbe r performanc e fall s belo w th e desig nvalue .



### 2- 3P.1 4

3 . THEOR YAN D PERFORMANC E O F CONVENTIONA L FIXE D BE D CARBO N ADSORBER S

Thi s sectio npresent s a genera l descriptio no f carbo nadsorber s use dt o remov e volatil e organi c compound s (VOC ) fro m a gaseou s proces s stream . Th e purpos e o f thi s presentatio ni s t o provid e informatio nnecessar y t o dra w conclusion s concernin g th e following :

• Th e abilit y

o f carbo nadsorber s t o remov e 9 5 percen t o r mor e o f the VO C ina proces s strea m onbot ha short-term an d long-term

basis ; t th e effec t o f variou s operatin g parameter s suc ha s solven t type , bed age , inle t stream

temperature , concentration , flowrate , an d regeneratio nstea

m flow onadsorbe r performance . Th e informatio npresente dher e wa s obtaine dfro m industr y

an dvendo r response s t o informatio nrequest s fro m EPA , evaluatio no f carbo nadsorbe r emissio ntes t dat a gathere dfo r thi s an dpreviou s EPA

studies , an

da meetin g wit ha majo r vendo r o f activate dcarbo nan dcarbo nadsorption/incineratio nsystems . Th e firs t par t o f thi s sectio ni s a discussio no f th e basi c theor y o f carbo nadsorptio n(Sectio n3.1) . Sectio n3. 2 describe s th e desig n consideration s fo r ful l scal e systems , Sectio n3. 3 present s a discussio no f ho w adsorbe r efficienc y i s calculated , andSectio n3. 4 present s th e impac t o f operatin g variable s onsystem performance . Sectio n3. 5 present s emissio ntes t dat a t o substantiat e th e performanc e o f carbo nadsorbers . Finall y Sectio n3. 6 present s conclusion s concernin g carbo nadsorbe r performance . 3. 1 MECHANIS M

O F ADSORPTIO N

AN D DESORPTIO N Thi s sectio npresent s a detaile ddescriptio no f th e mechanism s o f carbo n adsorptio nan

ddesorption . T o describ e th e mechanism s involved , a simplifie d approac husin g a singl e be do f activate dcarbo ni s developed . Th e principle s involve dinth e singl e be dsystem ar e the napplie dt o describ e th e operatio n o f a typica l carbo nadsorbe r system . Fo r ga s phas e carbo nadsorptio napplications , th e adsorbe r system doe s no t actuall y

recove r th e VOC . I t i s use dt o transfe r th e VO C fro m a mediu m wher e i t i s difficul t t o recove r (th e ven t stream gas) , t o a mor e concentrate dform

i na differen t medium (usuall y

steam ) wher e th e VO C ca nbe mor e easil y

recovered . Thi s transfe r occur s intwo steps . Th e firs t i s th e



### 3- 1P.1 5

adsorptio nste pwher e th e VO C (adsorbate ) i s adsorbe dont o th e surfac e o f activate dcarbo n(adsorbent) . Th e second ste p i s wher e th e adsorbat e i s remove dfro

m th e carbo n(desorption ) an drecovere d fo r reuse . Bot ho f thes e step s ar e equall y

importan t i

nth e overal l process . Th e adsorptio nproces s ca nb e eithe r physica l o r chemical . I nphysica l adsorptio nth e organi c molecul e i s hel dt o th e surfac e b y wea k vande r Waa l typ e force s o r intermolecula r cohesion . Th e chemical , natur e o f th e adsorbe d ga s remain s unchanged , thu s th e proces s i s readil y reversible . Regenerativ e pollutio ncontro l equipmen t require s th e adsorptio nproces s b e physical . I n chemica l adsorption , electron s ar e exchange dthu s chemicall y bondin g th e 2 molecul e t o th e surfac e o f th e carbo nparticle . Chemica l adsorptio ni s no t readil y reversibl e and , therefore , i s no t suitabl e fo r th e regenerativ e 3 adsorbe r system s use dinai r pollutio ncontro l applications . Figur e 3- 1 present s a serie s o f explode d view s whic hdescrib e th e subsystem s whic hmak e u pa carbo nadsorbe r bed . A carbo nbe di s comprise do f carbo npellets . Th e pellet s ar e mad e u po f carbo nparticle s whic hhav e bee n sintere dtogether . Th e carbo nuse dinadsorptio ni s mad e b y a tw o ste p process . Inth e first , materia l fro m variou s source s suc ha s coconu t shells , petroleu m products , woo dan

d coa l i s carbonize db y heatin g i t inth e absenc e o f ai r unti l al l organi c compound s excep t th e carbo nar e volatilized . The n usin g hig htemperatur e steam , air , o r carbo ndioxide , th e carbo ni s mad e 4 porou s o r activated . Dependin g upo nth e exten t o f thi s proces s an dth e origina l source , th e carbo nca nb e mad e t o fi t th e us e fo r whic hi t i s desired . Th e por e structur e withi na carbo nparticl e i s illustrate dinFigur e 3-2 . Th e externa l surfac e are a o f a carbo nparticl e i s a few squar e meter s pe r gram ; however , withi nth e pore s th e availabl e surfac e are a i s hundred s o f squar e meter s pe r gram . Th e pore s withi nth e carbo nar e classifie d accordin g t o their size . Larg e pore s (greate r tha n2,00 0 nanometer s i ndiameter ) ar e calle dmacropore s an dsmalle r pore s (les s tha n20 0 nanometers ) ar e calle dmicropores . Pore s wit hdiameter s betwee nthes e range s ar e calle dtransitiona l pores . Micropore s ar e wher e th e majorit y o f th e adsorptio noccur s s o i t i s desirabl e t o hav e a larg e amoun t o f th e por e spac e inthi s form .



### 3- 2P.1 6

Carbo n Pellets i n Cross Sectio n o

f Carbo n Be

d

Carbo n Particl e

c c o o 

## i Figur e 3-1
. Representatio n o

f Carbo n Pellets/Particles i n Carbo n Be d

3- 3Adsorbate Adsorben t
> / -

C O

. . . ' •. •. •

. . ••

•••



### Figur e 3-2
. Representatio n o f Pores i n Activate d Carbo n Particl eP.1 8

Th e adsorptio nproces s begin s wit hth e mechanica l movemen t o f th e ven t stream throug hth e carbo nbed , whic hbring s th e organi c molecule s int o contac t wit hth e carbo npellets . Th e remainde r o f th e adsorptio nproces s consist s o f thre e step s a s illustrate dinFigur e 3-3 . Th e adsorbat e mus t firs t diffus e int o th e carbo npelle t t o th e surfac e o f th e carbo nparticle . Next , th e adsorbat e molecul e mus t diffus e fro m th e surfac e int o th e pore s withi nthe carbo nparticle . Th e exten t o f th e diffusio nwithi nth e pore s i s dependen t o n th e siz e o f th e molecule s an dth e por e structur e o f th e carbon . Diffusio n int o th e large r pore s occur s fairl y rapidly , bu t a s th e por e diameter s become smalle r th e diffusin g molecul e strike s th e wall s an dstick s fo r shor t period s g o f time . Thi s diffusio nproces s continue s unti l th e molecul e reache s a locatio nwher e i t n o longe r ha s sufficien t energ y t o escap e th e force s whic h hol di t t o th e por e wall . Thi s usuall y occur s wher e th e por e diamete r i s no t
mor e tha napproximatel y twic e th e diamete r o f th e adsorbat e molecule . Th e adsorptio nproces s continue s unti l th e amoun t o f adsorbat e o nthe carbo nreache s a thermodynami c equilibriu m wit hth e adsorbat e inth e ga s phase . Th e thermodynami c equilibriu m i s a functio no f th e carbo ntype , temperatur e o f th e carbo nan dadsorbate , andth e adsorbat e partia l pressur e (concentration ) i nth e ven t stream . Th e amoun t o f adsorbat e a particula r carbo nca nhol di s calle dth e equilibriu m capacity . A s previousl y

mentioned , th e purpos e o f th e carbo nadsorbe r i s t o actuall y transfe r th e adsorbat e fro m th e ga s stream

t o a mediu

m wher e i t can mor e easil y

b e recovere do r dispose dof . Therefore , a t some poin t th e adsorbat e mus t b e remove dfro m th e carbon . Thi s proces s i s calle ddesorptio n o r regeneration . Desorptio ni s accomplishe d b y shiftin g th e thermodynami c equilibriu

m establishe ddurin g th e adsorptio nstep . Ther e ar e thre e way s t o shif t th e equilibrium : 1 ) increas e th e temperature , whic hi s usuall y brough t abou t b y th e additio no f steam , 2 ) reduc e th e pressur e o f th e atmospher e surroundin g th e carbon , and3 ) reduc e th e concentratio ni nth e ga s strea m outsid e th e carbo nt o a valu e les s tha nth e concentratio ninsid e th e carbon . Inmos t ai r pollutio ncontro l applications , increasin g th e temperatur e i s use d fo r desorption . Durin g desorptio nsome adsorbe dmolecule s ar e no t removed . Th e reaso ni s tha t t o remov e al l th e adsorbat e require s sufficien t time fo r th e adsorbat e



### 3- 5Ste p 1 : diffusio n t o adsorben t surfac e Ste p 2 : migratio n int o pore s of adsorben t Ste p 3 : monolaye r buildu p o f adsorbat e

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### Figur e 3-3
. Mechanis m o

f Adsorptio n o o o 0 0

Ic oP.2 0

molecule s t o diffus e ou t o f th e carbo nparticle , an dtha t th e temperatur e be hig henoug ht o caus e al l th e adsorbat e t o desorb . However , th e energ y cos t t o accomplis hthi s i s highe r tha nth e cos t t o leav e some adsorbat e inth e carbo n an dus e a large r amoun t o f carbo nt o achiev e th e desire dsystem performance . Adsorbat e remainin g inth e carbo nafte r desorptio ni s calle d th e heel . Th e amoun t o f hee l i s a functio no f th e desorptio ntim e an dtemperature . Increasin g adsorptio ntime and/o r temperatur e wil l reduc e th e heel . I nvirgi n carbon , a stabl e hee l i s establishe dafte r two t o thre e adsorption / desorptio n cycles . Th e proces s discusse dabov e i s summarize db y th e simplifie d representatio no f a carbo npor e show ninFigur e 3-4 . A s shown , th e por e ha s thre e differen t volumes : th e equilibriu m capacity , workin g capacity , an dth e 1 2 heel . A s previousl y discussed , th e equilibriu m capacit y

i s a functio no f th e carbo ntype , be dtemperature , an d th e partia l pressur e o f th e adsorbat e i n th e ven t stream . I t represent s th e maximu m amoun t o f adsorbat e whic hcanb e adsorbe db

y th e carbo nwhe ni t i s a t equilibriu m wit hth e surroundin g conditions . Th e hee l represent s th e adsorbat e whic hremain s inth e por e afte r desorption . I t i s a functio no f th e particula r carbon , th e adsorbate s i nthe ven t stream , an

dth e steamin g conditions . Th e practica l applicatio no f th e adsorptio nproces s t o a ful l siz e carbo n be di s illustrate dinFigur e 3-5 . Inthi s figure , th e solven t lade nai r (SLA ) flow s fro

m lef t t o right . A s shown , ther e ar e thre e zone s i nth e bed labele d saturated , mas s transfer , an dfresh . Th e saturate d zon e i s locate da t th e entranc e t o th e be dan drepresent s th e carbo nwhic hha s already adsorbe dit s workin g capacit y

o f adsorbate . Th e saturate dcarbo ni s a t thermodynami c equilibrium

wit hth e incomin g ven t stream . Therefore , n o ne t mas s transfe r occur s i nthi s zone . Th e mas s transfe r zon e (MTZ ) i s th e sectio no f th e carbo nbe dwher e th e adsorbat e i s remove dfro m th e carrie r stream . Th e carbo n inthi s zon e i s a t variou s degree s o f saturation , bu t i s stil l abl e t o adsor b
some adsorbate . Fo r a typica l system , th e mas s transfe r occur s withi na 1 3 sectio napproximatel y thre e inche s indepth . Th e fres hzon e i s downstream o f th e mas s transfe r zon e an drepresent s th e regio no f th e be dwher e no new adsorbat e ha s passe dsinc e th e las t regeneration . Thi s zon e stil l ha s al l it s workin g capacit y

(i.e. , equilibriu

m capacit y

minu s th e heel ) available .



### 3-7P.2 1

A = Residua l o r Hee l (locate d dee p i n th e por e an d difficul t t o dislodge) B = Workin g Capacity (bounded b y th e hee l remainin g fro m previou s cycle s an d portio n o f por e to o larg e i n diamete r t o retai n organic) C = Equilibriu m Capacity



# 1 Figure 3-4
. Simplifie d Representatio n o f Carbo n Capacity 1 2 

### 3

3- 8SL A Flo w
100 %

% O f Tota l Equilbriu m Capacity Availabl e

ut I v o Saturate d Zon e -• I Mas s I* - Transfe r Zon e Fres h Zon e Hee l

Remainin g Workin g Capacity

Distanc e Throug h Be d



### Figure 3-5
. Availabl e Workin g Capacity a s a Functio n of Distanc e

Throug h Bed fo r a n Operatin g Bed 8 8P.2 3

Durin g operatio nth e mas s transfe r zon e move s dow nth e bedinth e directio no f flow . Breakthroug hoccur s whe nth e mas s transfe r zon e firs t reache s th e bed outlet . Th e breakthroug hpoin t i s characterize db y th e beginnin g o f a shar p increas e inth e outle t concentration . Th e availabl e adsorptio ntime fo r a specifi c be dbefor e breakthroug hoccur s i s a functio no f th e amoun t o f carbo n present , it s workin g capacity , an dth e concentratio nan dmas s flowrat e o f adsorbate . Figur e 3- 6 show s a simplifie drepresentatio no f th e carbo npore s i neac h
o f th e thre e zones . Pore s A throug hE represen t typica l pore s a t differen t location s inth e bed . Por e A , whic hi s a t th e fron t o f th e bed , i s already completel y

saturate dwhil e Por e E , whic hha s no t bee nexpose dt o adsorbat e durin g thi s cycle , stil l retain s it s entir e workin g capacity . Pore s B , C , an d D whic har e locate dinth e MTZ , depic t variou s degree s o f saturation . A cros s sectio no f th e be dperpendicula r t o th e ai r flow wil l revea l pore s a t simila r level s o f saturation . Inth e MTZ , por e B ha s bee nexpose dt o th e adsorbat e fo r th e longes t perio do f time an di s nearl y

saturate dwhil e th e MT Z ha s jus t reache dpor e D whic hstil l retain s mos t o f it s adsorptiv e capacity . A s th e adsorptio ncycl e continue s an dmor e adsorbat e enter s th e bed , th e mas s transfe r zon e wil l continu e t o mov e throug hth e bed . Figur e 3- 7 depict s th e VO C concentratio nwithi nth e carrie r ga s a s a functio no f axia l distanc e dow nth e bed . Sinc e equilibrium ha s bee nreache d wit hth e incomin g adsorbat e inth e regio nprio r t o th e mas s transfe r zone , th e vapo r stream

concentratio ni s equa l t o th e inle t concentration . Withi nth e mas s transfe r zone , th e concentratio no f th e vapo r stream drop s of f becaus e th e organi c i s bein g adsorbe dint o th e pores . 1 4 Theoretically , th e concentratio ninth e thir dzon e shoul db e zero . However , a smal l amoun t o f adsorbat e i s typicall y present . Thi s i s a resul t
o f two factors : 1 . A smal l amoun t o f SLA ma y pas s throug hth e adsorbe r withou t actuall y contactin g th e carbon . 2 . Du e t o th e low

concentratio no f adsorbat e inth e ven t strea m inth e las t few inche s o f th e bed , th e hee l remainin g fro m th e previou s cycl e wil l slowl y

desorb .

3-1 0SL

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. Simplifie d Por

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\ Outlet Concentratio n



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### Figure 3-7
. Vapo r Strea m Concentratio n a s a Functio n o f Distanc e Throug h Be

d C E c-J §P.2 6

Tes t result s onful l scal e system s hav e show noutle t concentration s a s lo w 1 5 a s 0. 5 ppm . Thi s outle t concentratio nca nb e minimize db y prope r system design , a s discusse di nth e nex t section . Th e breakthroug hcurve , whic hi s th e outle t concentratio na s a functio n o f time , i s a mirro r imag e o f th e concentratio nprofil e inth e mas s transfe r zone . A s th e mas s transfe r zon e reache s th e en do f th e bed , th e outle t concentratio nrises . Thi s wil l continu e unti l th e outle t equal s th e inle t concentration . 3. 2 FUL L SCAL E ADSORPTIO N SYSTEM S Thi s sectio ndescribe s ful l scal e adsorptio nsystem desig nan

d operation . Th e basi c mechanism s wer e previousl y describe dinSectio n3.1 . Sectio n3.2. 1 present s a novervie w

o f th e adsorbe r system . Sectio n3.2. 2 discusse s specifi c desig nconsideration s fo r a ful l scal e system . 3.2. 1 Syste m

Overvie w Th e proces s flo

w diagra m fo r a typica l two be dcarbo nadsorbe r system i s show ni nFigur e 3-8 . Th e adsorbe r system ca nb e broke ndow

nint o thre e separat e sections ; pretreatment , carbo nadsorber , an d recovery/wast e treatment . Th e ven t stream containin g th e adsorbat e enter s th e adsorptio n system vi a th e pretreatmen t section . I f th e ven t stream i s abov e th e maximu m desig ntemperatur e i t i s reduce dwithi nth e pretreatmen t section , usuall y wit ha hea t exchanger . Inaddition , a filte r i s include dinth e pretreatmen t sectio nt o remov e an y particulat e presen t inth e ven t stream . Fro m th e pretreatmen t section , th e ven t stream enter s th e adsorber . Figur e 3- 8 depict s a two be dadsorbe r system . Inorde r t o provid e continuou s emissio ncontrol , a t leas t two adsorbe r bed s ar e neede ds o tha t
on e i s on-lin e whil e th e othe r i s regenerated . Adsorbe r system s wit hthre e o r mor e bed s ar e operate dsimilarly . Durin g operation , th e organic-lade nven t stream passe s throug hth e on-lin e be dfo r a predetermine dtime perio do r unti l breakthroug hoccurs . Th e on-lin e be di s the ntake noff-lin e fo r regeneratio n(desorption ) an dth e othe r be di s brough t on-line . Regeneratio no f th e off-lin e be di s usuall y accomplishe db

y passin g stea m throug hth e be dcountercurren t t o th e directio no f ven t strea m flow . Th e stea m whic hi s injecte dint o th e be dserve s severa l purposes ; 1 ) i t

3-1 3Vent Strea m

c a r

Filte r

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### Figur e 3-8
. Carbo n Adsorbe r Syste m Proces s Flo wDiagra m sprovide s th e energ y t o rais e an

dhol dth e be da t a

nelevate dtemperature , 2 ) i t provide s th e energ y require dt o desor bth e adsorbat e fro m th e carbon , an d3 ) i t carrie s th e desorbe dadsorbat e fro m th e bed . Th e stea

m i s condense d
an dthe ndecanted . Ther e ar e two liqui dphase s presen t inth e decanter , th e aqueou s an

dorganic . Th e organi c phas e i s generall y recovere dfo r reuse . Th e aqueou s phas e i s eithe r dispose do f or , i f th e leve l o f organic s i s high , treate dprio r t o disposal . Afte r th e desorptio nstep , th e bedi s sometime s drie dusin g heate dair . However , thi s i s no t require di nmos t case s becaus e removin g wate r fro

m th e carbo nusuall y

ha s littl e effec t onth e adsorptio n process . I

nfact , th e moistur e lef t onth e bedca nb e beneficia l becaus e i t act s a s a hea t sin k durin g th e adsorptio nprocess . Finally , th e regenerate dbe d i s the ncoole db y passin g ambien t ai r throug hit . I

na wel l designe dsystem bot hcoolin g an

ddryin g ar e performe d wit hth e ai r flow

countercurren t t o th e directio no f flow whe nth e adsorbe r i s on-line . Th e ai r exitin g th e regeneratin g be di s directe dthroug hth e on-lin e be dt o remov e an

y trac e adsorbate . 3.2. 2 Ful l Scal e System Desig nConsideration s Sectio n3.2. 1 discusse dth e overal l adsorptio nsystem . Thi s sectio n focuse s onth e desig no f th e adsorbe r sectio nitself . Bot hth e physica l system desig nan

dth e system

contro l an

doperatio ndurin g adsorptio nan d desorptio nar e importan t inorde r t o achiev e highremova l efficiencie s o na continuou s basis . Th e desig no f ful l scal e carbo nadsorptio nsystem s begin s wit ha determinatio no f th e inle t stream characteristics . Th e characteristic s whic hma y

b e importan t are :

• Specifi c compound(s ) present ;

• flowrat e an

dtemperatur e (rang e an daverage) ;

• adsorbat e concentratio n(rang e an d average ; an

d § relativ e humidity . Any commercia l activate dcarbo nshoul db e capabl e o f providin g acceptabl e performanc e i f th e system i s designe dbase dontha t particula r carbon . However , selectin g a carbo nwhic hha s a majorit y o f micropore s whic har e

3-1 5smalle r tha napproximatel y twic e th e diamete r o f th e adsorbat e molecules , wil l resul t inth e greates t adsorptiv e forces . Onc e th e carbo nha s bee nselected , th e require dbe dare a i s calculate d base donth e desire dsuperficia l velocity . Fo r a specifie dflowrate , the bed
are a determine s th e superficia l velocit y o f th e ven t stream

throug hth e bed . Th e lowe r limi t o f superficia l velocit y i s 2 0 ft/mi nt o insur e prope r ai r

1 8 distribution . Th e uppe r limi t i s usuall y 10 0 ft/min . Thi s uppe r limi t i s t o kee pbe dpressur e drop s withi nth e discharg e hea dcapacitie s o f th e type s o f fan s use dinthes e applications , an d t o avoi dexcessivel y hig hsystem

powe r costs . Typica l superficia l velocitie s ar e base donvendo r experienc e an dthe result s o f pilo t scal e testing an dwil l usuall y

b e betwee n5 0 an

d10 0 ft/min . 1 9 Generally , carbo nadsorbe r be ddepth s rang e fro m 1. 5 t o 3. 0 feet . A be ddept ho f a t leas t 1. 5 fee t i s use dt o insur e tha t th e be di s substantiall y 2 0 deepe r tha nth e MTZ , whic hi s normall y thre e inche s deep . I f th e MT Z i s longe r tha nth e bed , breakthroug hwil l occu r almos t immediately . Th e maximu m be ddept ho f thre e fee t i s base donkeepin g system pressur e dro pwithi n reasonabl e limits . Withi nth e constraint s discusse dabov e determinatio no f th e beddept h become s a functio no f th e volum e o f carbo nrequire dfo r on e adsorptio ncycle . Th e minimu

m volum e o f carbo ni s determine db y th e solven t mas s loading , the carbon' s workin g capacity , carbo ndensity , an dth e desire davailabl e adsorptio ntime . Th e solven t mas s loadin g an dcarbo ndensit y

ar e fixe db

y the stream bein g treate dan

dth e choice s o f carbon , respectively . Th e workin g capacit y an davailabl e adsorptio ntime ar e interrelate d an d ar e determine db

y th e particula r carbon , desig ntemperature , adsorbat e concentration , specifi c compound s present , superficia l velocity , an dregeneratio nparameters . Th e availabl e adsorptio ntime a s a minimu m mus t b e greate r tha nth e time require d t o regenerat e (stea

m an dcool ) th e off-lin e bed(s) . I f th e adsorbat e contain s multipl e organi c compounds , interaction s betwee nthos e compound s mus t als o b e considere dinth e estimatio no f working capacity . Mor e strongl y adsorbe dcompound s displac e th e les s strongl y

2 1 adsorbe dan

dpus hthem

throug hth e bed . Thi s create s a wav e fron t o f the lowe r molecula r weigh t compound s (whic htendt o b e th e compound s les s strongl y

3-1 6P.3 0

adsorbed ) a t th e fron t o f th e MTZ . Th e phenomeno nmus t b e accounte d fo r i n estimatin g th e system desig nworkin g capacit y t o insur e tha t breakthroug ho f
an y o f th e compound s doe s no t occur . A t thi s poin t i t i s necessar y t o determin e th e workin g capacit y an d specif y a nadsorptio ntime t o determin e th e carbo nvolume . Empirica l dat a fro m pilo t scal e testin g ar e usuall y require d t o accuratel y determin e workin g capacit y fo r a specifie d se t o f inle t conditions , superficia l velocity , an d desorptio nstea

m flow . However , th e desorptio nstea m flo w selected , i

nturn , affect s th e workin g capacit y an d th e minimu

m require d adsorptio ntime . Th e economi c trade-off s o f system capita l cost s versu s stea m cost s wil l determin e wha t se t o f regeneratio ncondition s wil l resul t inth e lowes t annua l costs . Steamin g requirement s ar e se t a s par t o f th e initia l system design . Th e longe r th e be d steamin g time th e greate r th e amoun t o f adsorbat e removed , an d therefor e th e smalle r th e amoun t o f removabl e hee l remaining . A s previousl y discussed , th e workin g capacit y o f a carbo nbed , whic hi s th e amoun t o f adsorbat e th e be d ca nremov e durin g anadsorption'cycle , i s th e differenc e betwee nth e hee l an

d th e equilibriu

m capacity . Therefore , th e longe r th e be d i s steamed , th e greate r th e availabl e workin g capacity . A nexampl e o f th e relationshi p o f workin g capacit y versu s stea

m consumptio nfo r thre e compound s 2 2 i s show ninFigur e 3-9 . Th e shap e o f thi s curv e i s simila r fo r mos t compounds . However , specifi c value s o f workin g capacit y versu s stea

m flo w var y fro m compoun d t o compound . Th e curv e usuall y begin s t o flatte nou t a t some steam

consumption . Increasin g steam us e beyond th e poin t wher e th e curv e begin s t o flatte nou t wil l resul t inonl y a smal l increas e inworkin g capacity . Inwel l designe d system s th e be d i s steame d countercurren t t o th e 2 3 directio no f flow

durin g adsorption . Thi s wil l hel p minimiz e th e adsorbat e emitte d a t th e adsorbe r outle t prio r t o breakthrough . Figur e 3-10 , whic hi s a plo t o f th e adsorbat e concentratio nlef t onth e be d afte r steamin g a s a functio no f axia l distanc e throug hth e bed , illustrate s why thi s i s true . Afte r steaming , th e concentratio no f adsorbat e (i.e. , th e amoun t o f hee l whic h remains ) i s lowe r a t th e en d o f th e be d wher e th e stea m enters . Whe nthe adsorbe r i s brough t on-line , th e lowe r amoun t o f hee l wher e th e SL A exit s th e be d mean s les s adsorbat e i s availabl e t o desorb . Also , havin g mor e workin g

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### Figure 3-9
. Stea m Consumptio n versu s Workin g Capacitie s tc 

### 3 S

T J CO

# < 1 Directio n o

f Adsorptio n Ai r Flo

w
Directio n o

f Stea m Flo

w 

# e >

CO I I— * Adsorbat e Lef t o n Be d Afte r Steamin g *

Distanc e Throug h Bed



### Figur e 3-10
. Adsorbat e Concentratio n i n Be d Afte r Steamin g Countercurrentl y a s a Functio n o

f Distanc e Throug h Be d < r CO o y O 

### scapacit y availabl e a t th e bed exi t help s preven t momentar y increase s i

noutle t concentratio na s a resul t o f change s i ninle t condition s cause d b y proces s upsets . I f th e be d i s steame d cocurren t t o th e directio no f flow durin g adsorption , th e revers e hee l profil e exist s an d a highe r outle t concentration s wil l result . Anothe r consideratio ninadsorbe r desig ni s fouling . Foulin g occur s whe n compound s ar e presen t inth e ven t strea m whic hwil l no t desor bfro m th e bed . Thes e compound s ca nb e soli d particles , highmolecula r weigh t compounds , o r compound s whic hchemicall y reac t o

nth e surfac e o f th e carbo n(suc ha s som e ketones) . Regardles s o f th e source , be d foulin g graduall y reduce s th e carbo n adsorptio ncapacity . Ther e ar e tw

o method s t o compensat e fo r fouling . On e i s t o increas e volum e o f carbo nbeyon d th e minimu m require d t o achiev e th e desire d adsorptio n time . Th e second i s t o graduall y increas e th e amoun t o f steam use d t o regenerat e th e bed . Increasin g th e steam use d inregeneratio nreduce s th e heel , whic hhelp s maintai nsufficien t workin g capacity . A combinatio no f thes e method s ca nals o b e used . A typica l adsorption/desorptio ncyclin g arrangemen t fo r a tw o bed adsorbe r system

i s show

ni nFigur e 3-11 . Fo r th e purpos e o f discussion , illustrativ e time s ar e show nonth e figur e correspondin g t o operationa l aspect s o f th e system . Th e sequenc e begin s wit hbe d 1 comin g on-lin e a s be d 2 goe s off-lin e a t t . Fo r th e exampl e shown , adsorptio nlast s 9 0 minutes , th e steamin g tim e i s fixe d a t 3 0 minutes , an d th e cooling/dryin g time i s als o 3 0 minutes . Th e off-lin e be d ha s 3 0 minute s durin g whic hi t i s onstandby . Inthi s example , th e 3 0 minute s o f standb y time allow s th e operato r t o compensat e any

dail y variation s i nven t stream condition s an

d be d foulin g withou t havin g t o leav e a be d on-lin e afte r breakthrough . I t i s importan t tha t a be d no t b e lef t on-lin e afte r breakthroug hbecaus e tha t wil l significantl y

reduc e th e overal l remova l efficienc y fo r tha t cycle . Two type s o f trigge r mechanism s ar e use d fo r controllin g th e adsorption / desorptio ncycles : continuou s monitor s an d timers . Continuou s monitor s tak e a be d off-lin e whe na specifie d outle t concentratio ni s reached . Timer s cycl e th e be d a t a specifie d time . A combinatio nma y

als o b e used . On e advantag e t o usin g continuou s monitor s i s tha t the y allow th e bed s t o remai non-lin e

3-2 0Bed# 1

Tim e (min ) Adsorptio n

T " 3 0 6 0 

### Regeneratio n
Steamin g | Dryin g I Stand-B y 9 0 120 15 0 180 Adsorptio n i 21 0 -T —

24 0 27 0

ut i r o Be

d # 2

Tim e (min ) 

### Regeneratio n

I Steamin g i Dryin g i Stand-B y Adsorptio n

3 0 6 0 9 0 120 i 15 0 

### Regeneratio n

Steamin g | Dryin g - Stand-B y 180 21 0 24 0 27 0



### Figur e 3-11
. Adsorption/Desorptio n Cycle s i n a 2 Be d Syste m sP.3 5

unti l breakthrough , thu s full y utilizin g thei r capacit y durin g eac hcycle . Thi s i s no t th e cas e fo r a time r base dsystem , becaus e t o properl y guar d against breakthroug hallowance s mus t b e mad e fo r variation s inth e breakthroug htime du e t o change s inth e inle t stream characteristics . Althoug hcontinuou s monitor s allow fo r th e us e o f mor e o f th e availabl e adsorptio ncapacit y

tha ntimers , do , timer s ca nb e use dinmany situation s a s th e trigge r mechanism . The y ar e especiall y

appropriat e fo r adsorbate s whic h d o no t fou l th e be do r wher e inle t stream characteristic s ar e ver y stable . I f
a time r i s used , continuou s monitor s o r a periodi c samplin g program shoul dbe use dt o adjus t th e adsorptio ntime s a s necessary . Deviation s inoperatin g condition s d o no t affec t properl y designe d system s whic hus e timer s unles s the condition s excee dth e rang e o f th e desig nspecifications . I f thi s i s allowe d t o occur , a be dma y

b e kep t on-lin e afte r breakthroug hha s occurred , Thi s woul dresul t ina significantl y reduce d remova l efficiency . A final , an

dimportant , consideratio ninsyste m desig ni s preventio no f channeling . Channelin g occur s whe na portio no f th e SLA bypasse s th e bed , o r a certai nsectio no f th e be dreceive s a greate r portio no f th e flow tha nothe r sections . Th e inle t o f th e vesse l mus t b e designe dt o achiev e prope r distributio no f th e SLA s o tha t i t doe s no t imping e ona portio no f th e bedat hig hvelocity . Th e potentia l fo r channelin g ca nb e minimize db y th e us e o f distributio nbaffles . I t i s als o importan t t o achiev e prope r distributio no f th e regeneratio nsteam . I f steam i s no t wel l distribute dth e stea m flo w can als o caus e channel s t o for m inth e bed . Also , poo r steam distributio nwil l resul t i nsome portio no f th e be dno t bein g properl y regenerated . Prope r desig nca nminimiz e th e potentia l fo r channeling . However , maintenanc e o f th e distributio nbaffle s an dsteam distributio nsystem shoul d b e performe ddurin g schedule dsystem shutdown s o r wheneve r a nincreas e i s detecte di nth e adsorbe r outle t VO C concentratio nwhic hi s significan t enoug h t o resul t i na remova l efficienc y belo w th e minimum

desig nlevel . 3. 3 CARBO N

ADSORBE RLONG - AN D SHORT-TERM EFFICIENC Y Thi s sectio ndiscusse s th e relationshi po f lon g andshort-term carbo n adsorbe r efficiency . Sectio n3.3. 1 discusse s th e calculatio no f instantaneou s

3-2 2P.3 6

versu s cycl e efficiency . Sectio n3.3. 2 discusse s th e variabilit y o f short-term

efficiency . Sectio n3.3. 3 discusse s th e relationshi po f outle t concentratio nan

defficiency . 3.3. 1 Calculatio no f Carbo nAdsorbe r Efficienc y Inorde r t o discus s carbo nadsorbe r long - an dshort-term

efficiency , a shor t discussio no f th e relationshi po f efficienc y t o th e inle t an

doutle t concentration s ove r time i s necessary . Th e inle t an

doutle t concentratio na s a functio no f time fo r a singl e adsorptio ncycl e o f a typica l carbo nadsorbe r i s show ni nFigur e 3-12 . Th e outle t concentratio ncurv e i s als o calle dth e breakthroug hcurve . Fo r the exampl e shown , th e inle t concentratio ni s C . an dth e outle t concentratio ni s
• C . Th e adsorbe r wa s brough t on-lin e a t t Q an dtake noff-lin e a t t - whe nthe outle t concentratio nreache dsom e predetermine dse t poin t concentratio nlevel . A t an y poin t intime th e instantaneou s remova l efficienc y (IRE ) fo r thi s adsorbe r i s determine da s th e differenc e betwee nth e inle t an doutle t concentratio ndivide db y th e inle t concentration . A t time t , th e instantaneou s remova l efficienc y is :

C

- i " C n -*E * - " ^
Th e overal l remova l efficienc y (ORE ) a t an

y give ntime durin g th e cycl e i s determine db

y th e differenc e betwee nth e area s unde r th e inle t an doutle t curve s divide db

y th e are a unde r th e outle t curve . Fo r th e adsorbe r show n inFigure s 3-1 2 a t tim e t , th e overal l remova l efficienc y is : ORE , = • Are a (ADEF ) - Are a (BCEF ) 1 Are a (ADEF )
A s anexample , i nth e magneti c tap e manufacturin g industr y a typica l inle t concentratio nmigh t b e 300 0 ppm v anda typica l outle t concentratio nmigh t be 2 4 3 0 ppm v o r les s prio r t o breakthrough . T o achiev e a 9 5 percen t remova l efficienc y

ove r th e perio do f a nadsorptio ncycl e a system wit ha ninle t concentratio no f 3,00 0 pp m mus t hav e a time weighte daverag e outle t concentratio no f 15 0 pp m o r less . A t a

noutle t concentratio no f 3 0 ppm v the remova l efficienc y

i s 9 9 percen t fo r mos t o f th e cycle . Therefore , whe n breakthroug hoccur s th e outle t concentratio nca nris e abov e th e 15 0 pp m poin t

3-2 3

### c 4 

### -

c 

### o

c ( D U c 

### Remova l Efficienc y a t t , Instantaneou s = I --=-

* C,-C „ 10 0

ut I r o 

### c„ - " j p 

### Overal l = f Are^ADEF ) - AreatBCEF A \ Area(ADEF) / C , = Inlet Concentratio n C 0 

### = Outlet Concentratio n C ap 

### - Se t Poin t Concentratio n

c „ - B

E T t
. C F t , 

### Tim e T -

t ,

CL i n 

### Figur e 3-12
. Determinatio n o f Carbo n Adsorbe r Remova l Efficienc ywithou t th e overal l remova l efficienc y goin g below

o f th e require d 9 5 percent . Therefore , fo r a system designe dan

doperate dt o maintai na certai nminimu m instantaneou s remova l efficiency , th e cycl e efficienc y wil l b e highe r thanth e instantaneou s efficiency . A t on e sit e th e cyclin g se t poin t fo r thei r syste m i s 2 hour s o r wheneve r th e instantaneou s remova l efficienc y reache s 9 5 percent . Th e resul t i s a noveral l remova l efficienc y greate r tha n 2 5 9 9 percent . 3.3. 2 Variabilit y

o f Short-Term

Remova l Efficienc y A significan t issu e raise di s th e variabilit y o f short-term

carbo n adsorbe r remova l efficiency . Assumin g tha t inle t stream characteristic s neve r vary , an dth e adsorbe r i s alway s operate dth e sam e way , cycl e efficiencie s 2 6 shoul db e almos t identical . Th e onl y chang e expecte dwoul db e a gradua l decreas e incarbo nworkin g capacit y du e t o be daging . However , th e chang e i n performanc e fro

m on e cycl e t o th e nex t du e t o be dagin g wil l b e insignificant . However , i nactua l applications , inle t stream characteristic s suc ha s concentration , temperature , an dflowrat e ma y

vary . Also , th e operato r ma y mak e deliberat e change s inth e solven t bein g adsorbed , o r insystem operation . I f fo r a wel l designe dan doperate dsystem

i t ca nb e show

ntha t change s i

n inle t stream

characteristic s o r operatio nd o no t significantl y affec t cycle-to-cycl e efficiency , the nth e short-ter m remova l efficienc y

ca nbe expecte dt o b e essentiall y constan t fo r industria l applications . Thes e evaluation s ar e show ninSectio n3-4 . 3.3. 3 Relationshi po f Outle t Concentratio nan dEfficienc y A typica l plo t o f inle t an doutle t concentration s versu s time fo r a carbo nadsorbe r wa s previousl y presente dinFigur e 3-12 . Figur e 3-1 3 present s a simila r curv e fo r th e outle t concentratio nonly . Inthi s exampl e Y represent s th e outle t concentratio na t th e beginnin g o f th e cycle . At the breakthroug htim e th e outle t concentratio nbegin s a shar p increase . At thi s time a fres hbe dshoul db e pu t on-line , an dth e othe r be dwhic hha s jus t broke nthroug hregenerated . Th e dashe dlin e represent s wha t happen s i f th e operato r doe s no t remov e th e be dwhic hha s broke nthroug hfro m service . Th e outle t concentratio nwil l increas e unti l i t equal s th e adsorbe r inle t concentration , whic hinthi s exampl e i s X .

3-2 5P.3 9

X 

### c o

mma C O 

### c o u c 

### 5 " 3 O 

# £ Point wher e bed shoul d b e take n off-line
. \


# <5 X Outlet concentratio n curv e whic h result s i f bed i s no t take n off-lin e a

t breakthrough
.

I brmakthrtmgh 

### Tim e • saturation



### Figure 3-13
. Typica l Carbo n Adsorptio n Breakthroug h Curv e §

3-2 6P.4 0

Als o show

ninthi s figur e ar e arrow s labele d"A " an d"B" . Thes e arrow s represen t th e two possibl e shift s inth e breakthroug hcurv e whic hcoul doccur . Th e shif t labele d"A " indicate s a decreas e inth e adsorptio ncycl e time prio r t o breakthrough . A

shif t o f thi s typ e normall y shoul dhav e littl e effec t o n th e efficienc y

o f th e adsorber , becaus e th e be dca nb e take noff-lin e fo r regeneratio nprio r t o th e releas e o f an y significan t emissions . A sligh t efficienc y

reductio nove r multipl e cycle s wil l occu r becaus e breakthroug hwil l
occu r mor e frequently . Th e magnitud e o f th e efficienc y change , however , wil l b e ver y smal1 . A shif t o f th e A

typ e wil l significantl y affec t efficienc y

i f a bedi s lef t on-lin e afte r breakthrough . Ther e ar e thre e possibl e reason s fo r a bed t o b e lef t on-lin e afte r breakthrough . 1 . Th e operato r ma y no t b e awar e o f how quickl y th e concentratio nrise s afte r breakthroug han d th e resultin g deleteriou s effec t onth e efficienc y

o f hi s adsorptio nsystem . 2 . Th e operato r ma y hav e n o wa y

o f knowin g whe nbreakthroug hoccur s (suitabl e analytica l instrument s hav e no t bee ninstalled) . 3 . Th e operato r ma y no t hav e a replacemen t be dproperl y desorbe dan

d cooled , ready

fo r service . Th e firs t two reason s ar e operationa l problem s an deasil y overcome . Th e thir dshoul dno t occu r i f th e system wa s designe dproperl y an di s bein g operate dwithi nth e desig nspecifications , an dth e carbo ni s replace dwhe n necessary . I f bed s ar e lef t on-lin e afte r breakthroug hremova l efficiencie s wil l als o becom e muchmor e variable . A s a nexample , assum e tha t th e adsorbe r system discusse di nSectio n3.3. 1 ha s a thre e hou r adsorptio ntime a t whic h poin t breakthroug hoccurs , a 3,00 0 ppm v inle t concentration , an da 3 0 ppm

v outle t concentration . Du e t o a proces s chang e th e inle t concentratio no f VO C
no w increase s t o 3,50 0 ppmv . occasionall y andthi s variabilit y wa s no t accounte dfo r inth e system design . Inthi s case , breakthroug hwoul dno w occu r approximatel y

2 6 minute s earlier . I f th e operato r doe s no t tak e th e bed off-lin e a t thi s time , th e outle t concentratio nincrease s ver y quickl y t o 3,50 0 ppm , an

dfo r tha t cycl e th e adsorbe r efficienc y wil l b e reduce dt o approximatel y

8 5 percent . I f th e inle t concentratio nvarie s fro m 3,00 0 to

3-2 7P.4 1

3,50 0 pp m ona dail y

basis , the nth e adsorbe r remova l efficienc y wil l als o var y fro m 9 9 t o 8 5 percen t o

na dail y

basis . Thi s exampl e demonstrate s tha t i f th e system

i s no t designe dt o accoun t fo r norma l proces s variations , efficienc y

wil l bot hb e reduced , an dbecome muc hmor e variabl e tha ni s normall y th e cas e wit hwel l designe dan doperate dsystems . Th e shif t "B " indicate s anincreas e inth e baselin e outle t concentratio n prio r t o breakthrough . A shif t o f thi s typ e coul dresul t ina significan t decreas e i nth e remova l efficienc y achievabl e b

y th e adsorbe r dependin g o nth e inle t concentratio nan dth e magnitud e o f th e outle t concentratio nchange . Fo r th e purpos e o f thi s analysis , i t i s importan t t o understan dth e tw o potentia l shift s inth e breakthroug hcurv e relativ e t o th e adsorptio n mechanis m

itself . Assumin g a constan t adsorbat e loadin g rate , a shif t o f typ e "A " indicate s a chang e inth e workin g capacit y o f th e carbo nfo r a give n adsorbate . Th e workin g capacit y i s a functio no f foulin g an dth e equilibriu

m condition s (i.e. , temperature , pressure , an dpartia l pressur e o f th e adsorbate ) fo r a particula r se t o f operatin g condition s (i.e. , steamin g time , temperature , an

dduration) . Therefore , change s inth e equilibriu m condition s whic heffec t th e workin g capacit y lea dt o typ e "A " shift s inth e breakthroug h
curve . A shif t o f typ e "B " indicate s on e o f two possibilities : 1 ) A portio no f th e inle t stream

ha s bypasse dth e be db y eithe r shor t circuitin g o r channelin g (a s previousl y

discussed , channelin g ca nb e avoide dwit hprope r desig nan d maintenance) . 2 ) A greate r amoun t o f hee l i s presen t inth e las t fe w inche s o f th e carbo nbed . A s state dpreviously , th e amoun t o f hee l i s a functio no f th e condition s whic har e establishe da t th e en do f th e steamin g cycle . Th e amoun t o f hee l relate dt o th e steamin g time , temperature , an dflow . Eac ho f th e potentia l operationa l variable s fo r a carbo nadsorbe r i s evaluate di nth e nex t sectio nrelativ e t o it s abilit y t o shif t th e breakthroug hcurv e o f Figur e 3-1 3 i neithe r th e "A " o r "B " direction . Prope r operatio npractice s necessar y t o preven t degradatio no f th e adsorbe r syste m ar e als o discusse dwher e appropriate . Th e result s fro m thi s evaluatio nar e the nuse dt o determin e th e effec t o nth e remova l efficienc y whic hi s

3-2 8achievabl e b y th e system . I

npresentin g thi s discussion , dat a an d informatio n availabl e fro

m industry , vendor s an d emissio ntes t report s ar e use d wher e available . 3. 4 EFFEC T O F OPERATINGVARIABLE S O N ADSORBE RPERFORMANC E Th e objectiv e o f thi s sectio ni s t o determin e i f th e norma l expecte d day-to-da y

proces s variation s woul d b e expecte d t o necessaril y caus e dail y variation s incarbo nadsorbe r performance . Als o assesse d ar e impact s o f deliberat e proces s changes , suc ha s a chang e insolvent , o nadsorbe r performance . Potentia l dail y operatin g variable s includ e th e operatin g temperature , inle t adsorbat e concentration , humidity , volumetri c flowrate , an d be d fouling . Change s fro m th e initia l desig noperatin g condition s includ e th e adsorbat e types(s) , an d steamin g conditions . Channelin g wil l als o b e discussed . Eac ho f th e dail y

norma l operationa l variable s i s evaluate d relativ e t o it s effec t onth e breakthroug hcurv e fro m a typica l carbo nadsorbe r bed . Fo r th e purpos e o f thi s discussion , th e assumptio ni s mad e tha t an y affec t o

nthe performanc e o f a singl e be d ma y b e take na s representativ e o f th e effec t o n th e overal l adsorbe r system' s performance . 3.4. 1 Temperatur e Th e operatin g temperatur e o f anadsorbe r ca nb e affecte d inthre e ways : change s i nth e inle t stream temperature , exothermi c chemica l reaction s takin g plac e insid e th e adsorber , o r failur e o f th e coolin g ste p afte r regeneration . Change s i nth e inle t stream' s temperatur e lea d t o change s i nth e adsorbe r operatin g temperature . Change s i nth e inle t solven t loadin g ca nchang e the rat e o f hea t generatio ndu e t o th e hea t o f adsorption . Hea t ca nals o be generate d withi nth e system fro m chemica l reaction s takin g plac e o nth e bed . Ketone s i nparticular , hav e bee nidentifie d b y severa l studie s a s particularl y 2 7 reactiv e compounds . Th e problem i s usuall y

no t serious , however , unles s the concentratio no f adsorbat e i s extremel y high , th e ga s flowrat e throug hth e carbo ni s relativel y

low , an

d th e carbo ni s dr y

an d contain s n o heel . Eac ho f th e possibl e scenario s give nabov e result s i na variatio ni nthe temperatur e a t whic hth e adsorptio nproces s take s place . Therefore , th e effec t o f temperatur e onth e breakthroug hcurv e mus t b e evaluated . A s

3-2 9previousl y discussed , th e tw

o possibl e shif t direction s "A " an d "B " ca nb

e assesse d b

y studyin g th e effec t o f temperatur e o nth e workin g capacit y an d the heel , respectively . A s show ninFigur e 3-14 , th e relationshi p betwee ncarbo n capacit y an d temperatur e indicate s tha t a s th e temperatur e withi nth e bed increases , th e adsorptiv e capacit y o f th e carbo ndecreases . Thus , a s the temperatur e increases , th e workin g capacit y o f th e carbo nals o decreases . Therefore , a shif t inth e breakthroug hcurv e i s t o th e lef t o r t o shorte r adsorptio ntimes . A shif t i nthi s directio nha s no effec t o nth e achievabl e remova l efficienc y

bu t doe s requir e a chang e inth e cycl e time t o compensat e fo r th e shift . Change s inoperatin g temperatur e shoul d no t caus e a B shif t inth e breakthroug hcurve . Thi s i s becaus e th e outle t concentratio na t th e beginnin g o f th e cycl e i s primaril y a functio no f th e hee l remainin g inth e las t fe w inche s o f th e bed . Th e amoun t o f hee l i s establishe d b y th e bed steamin g condition s durin g desorption . Onl y i f th e temperatur e o f th e carbo ninthe adsorbe r rise s t o value s clos e t o thos e durin g steamin g i s ther e a chanc e the removabl e hee l wil l desor ban d subsequentl y

decreas e th e achievabl e remova l efficiency . Temperatur e fluctuation s inth e inle t strea m ca nb e essentiall y eliminate d wit hinstallatio no f a hea t exchange r upstream o f th e carbo n adsorber . A

properl y

designe d system

wil l no t permi t th e inle t temperatur e t o excee d th e maximu

m desig ntemperature . T o illustrat e th e insensitivit y o f carbo nadsorbe r efficienc y t o mino r change s i nth e be d temperature , th e bed temperatur e an d th e correspondin g instantaneou s remova l efficiencie s fo r anoperatin g adsorbe r system ar e 2 8 presente d inFigur e 3-15 . A s shown , th e carbo nbe d temperatur e varie s fro m 6 0 t o 90° F durin g th e adsorptio ncycl e whil e th e correspondin g remova l efficiencie s remai nwel l abov e 9 9 percent . Th e outle t VO C concentratio n 2 9 remaine d constan t a t approximatel y 2 0 ppm . A s discusse d inth e sectio ndescribin g th e effec t o f change s inth e adsorbates , ketone s ar e know nt o exothermicall y

polymeriz e onth e carbo nbed . A system designe d fo r ketone s mus t assur e th e ai r flow throug hth e bed i s sufficien t t o remov e th e hea t o f reactio nt o insur e th e bed temperatur e i s no t 3 0 b e significantl y

affected .

3-3 0ut



### Temperatur e

I T a> 

### Figur e 3-14
. Carbo n Capacit y vs . Temperatur e a t Constan t Pressur e100

c o t o r o C D

+-a < 0 k

_ C D Q
. 

### E
< D Legen d

•Be d Temperatur

e

•Efficiency
" 1 — 13 0 T —

15 0 100

3 3 C D 

### 3 o < 

### 8 0 § g CD " O
-7 0



### Time , minute

s
Figur e 3-15
. Carbo n Adsorbe r Remova l Efficiency wit h Varyin g Be d Temperatur e fo r a Complet e Adsorptio n Cycl e COP.4 6

A properl y

designe dan

doperate dsystem

wil l limi t unacceptabl e hea t buildu pdu e t o reaction s inth e inan y o f th e followin g ways :

• Thoroug hstea

m desorptio nan

dcoo l down ,
e us e o f th e maximu m superficia l velocit y t o ai dinhea t removal , t avoidin g prolonge dadsorptio nperiods , an d

• humidit y

contro l o r eve nus e o f liqui dwate r t o ac t a s a hea t sink . Whe na system

i s designe dt o handl e a ketone-bearin g stream , be d temperatur e i s normall y

monitore dt o detec t ho t spot s an dinitiat e protectiv e actio nfo r th e carbo nbed . 3.4. 2 Concentratio n Th e concentratio no f organic s i nth e inle t strea m ma y var y becaus e o f proces s changes . Short-ter m variation s ar e thos e whic hoccu r withi na give n cycl e whil e lon g term variation s ma y

las t ove r severa l cycles . Change s ca n occu r a s equipmen t o r produc t line s ar e eithe r brough t ono r take noff-line . Fo r th e purpos e o f thi s discussion , th e flowrat e throug hth e be di s assume dt o remai nconstant . Therefore , whe nth e concentratio nincreases , th e loadin g rat e t o th e adsorbe r increases . Increasin g th e concentratio nwil l increas e th e workin g capacit y o f th e carbon . However , th e workin g capacit y increas e wil l no t b e larg e enoug ht o completel y

offse t th e increas e inmas s loading . Therefore , th e ne t effec t wil l b e a breakthroug hcurv e shif t inth e A direction . Th e effec t o f variation s i ninle t concentratio nonth e outle t concentratio nprio r t o breakthroug hshoul db e negligible . A s state dpreviously , th e outle t concentratio ni s a functio no f th e hee l i nth e las t few inche s o f th e bedtha t remain s afte r regeneration . Becaus e th e inle t stream reache s equilibriu

m wit h th e carbo nwithi nth e mas s transfe r zone , th e amoun t o f hee l a t th e adsorbe r outle t i s independen t o f inle t concentration . Therefore , short-term variation s inth e inle t concentratio nwil l no t caus e a B shif t inth e breakthroug hcurve . T o illustrat e th e independenc e o f th e outle t concentratio nonshort-term variation s i nth e inle t concentration , th e inle t an doutle t concentratio nan d correspondin g remova l efficienc y fo r a noperatin g adsorbe r system ar e

3-3 3presente dinFigur e 3-16 . (GT RTes t #6) 3 1 A s show ninFigur e 3-1 6 th e inle t concentratio nvarie s continuousl y ove r th e si xhou r perio d show nwhil e the correspondin g outle t concentration s an dremova l efficiencie s sho w littl e variation . Fo r inle t variation s betwee n20 0 an d55 0 pp

m th e outle t concentratio nvarie s onl y fro m 5 t o 1 5 pp

m an dth e correspondin g remova l efficienc y

varie s fro

m 9 5 t o 9 9 percent . Figur e 3-1 7 als o present s inle t concentration , outle t concentration , an d th e correspondin g remova l efficienc y fo r a simila r performanc e tes t conducte d

3 2 onth e same adsorbe r system discusse d above . A s show ninFigur e 3-17 , the outle t concentratio n( 0 t o 5 ppm ) remain s relativel y constan t fo r th e entir e tes t period , althoug hth e inle t concentratio nvarie s fro m 4 0 pp m t o 88 0 ppm . Figur e 3-1 7 als o show s th e remova l efficienc y ove r th e tes t period . Durin g th e majorit y

o f th e tes t perio dth e remova l efficienc y wa s wel l abov e 9 5 percent . However , whe nth e inle t concentratio ndroppe dbelow 5 0 ppm , the remova l efficienc y

wa s als o significantl y reduced . Thi s i s a s expecte d becaus e carbo nadsorber s ar e essentiall y constan t outle t devices , s o a larg e decreas e ininle t concentratio nwil l reduc e short-term remova l efficiency . Becaus e th e outle t concentratio nremain s constan t throughou t a n adsorptio ncycle , larg e variation s i nth e inle t concentratio nwil l resul t i n correspondin g variation s i nremova l efficiency . However , i f th e be di s properl y regenerated , th e outle t concentratio nca nb e se t a t a leve l wher e greate r tha n9 5 percen t remova l i s achieve d fo r th e entir e rang e o f inle t concentrations . Inaddition , i nman y application s o f carbo nadsorption , a reductio ni ninle t concentratio ni s th e resul t o f equipmen t (suc ha s coatin g lines ) bein g shu t down . By divertin g o r shuttin g of f th e ai r flo w fro m idl e equipment , inle t concentration s ca nb e maintaine da t highe r level s require dt o ensur e th e desire dremova l efficiency . 3.4. 3 Humidit y Workin g capacit y

a s a functio no f stea m consumptio ni s show nfo r relativ e 3 3 humiditie s o f 5 0 an

d10 0 percent , i nFigur e 3-18 . A s shown , relativ e humidit y doe s no t significantl y affec t workin g capacity . Thi s i s generall y 3 4 th e cas e fo r adsorbat e concentration s greate r tha n1,00 0 ppm . Therefore , ther e shoul db e onl y

a sligh t chang e inth e breakthroug htime associate dwit h variation s inrelativ e humidit y inthi s case .

3-3 4a-y 50 0 E a a
C 40 0 o
c • u c o u

c

1 a 1 — , 

# r 

# r

— i 1 

# " I n

10:0 0 11:0 0 12:0 0 13:0 0 14:0 0 15:0 0 16:0 0
Tim
. Inle t Concentratio n vs
. Tim e

E a a
\m* C o aa O %. ma C • U c o o 3 o

10:0 0 11:0 0 12:0 0 13:0 0 140 0 15:0 0 16:0 0
Tim * Outle t Concentratio n va
. Tim e

> » u c

U l o > o E

9:0 0 100 0 11:0 0 12:0 0 1 3 0 0 1 4 0 0 15:0 0 18:0 0
Tim . Removal Efficiencyva
. Tim e Figur e 3-16 . GT R Tes t Numbe r 6 Continuou s inlet/outle t VO C concentratio ndat a

an d remova l efficiency . 3-3 5P.4 9

E a a.
• ^ c o

c • u c o U

ma • C 90 0 -

i

80 0 -

70 0 -

60 0 -

50 0 -

40 0 -

30 0 -

20 0 - 1

10 0 - 

# , r* V

T 

# 1



# V

1 

# 1

-a — 9 0 0 120 0
Tim « Inle t Concentratio n vs
. Tim e

E a a
C o o L
. c • u c o u

3 o

9:0 0 12:0 0

> . U c

mm

o > o E 10 0 9 9 - ae 9 7 - 9 6 9 5 9 4 - 9 3 9 2 9 1 9 0 - 8 9 8 8 8 7 8 6 8 5 - 8 4 8 3 8 2 - 8 1 8 0 Tim« Outle tConcentratio n va . Tim e

9:0 0 10:0 0 11:0 0

Remova l Efficienc y va . Tim e Figur e 3-17 . GT R Tes t Numbe r 5 Continuou s Inlet/outle t VO C concentratio ndat a

an d remova l efficiency . 3-3 61 5

c o J Q k

_ c s O CO J Q O o • C 1 0 o c c « a > 

### EPA Strea m B

Toluen e - 60 0 pp m ME K-1,00 0 pp m Cyclohexanon e - 40 0 pp m Adsorptio n - 7 5 fp m

50 % Relativ

e Humidit

y
C O I C O *»s l C O

J 3

U C O Q
. c a 

## o c 100 % Relative Humidity

1. 0 1.5 

### lbs

. Steam/lbs

. Carbo n 2. 0

o r 

### 3 

### Figur e 3-18
. Effec t o f Relativ e Humidit y o n Workin g Capacit y

T J biP.5 1

Below adsorbat e concentration s o f 1,00 0 pp m wate r begin s t o compet e wit h adsorbat e fo r th e availabl e adsorptio nsite s an dth e be dworkin g capacit y fo r tha t adsorbat e i s the naffected . I nthi s case , som

e typ e o f dehumidificatio n system upstream

o f th e be do r dilutio nwit hambien t ai r ma y b e required . Relativ e humidit y

ha s n o effec t o

nth e amoun t o f hee l whic hi s retaine d withi nth e carbo npore . Therefore , ther e i s no B shif t inth e breakthroug h
curv e an dn o subsequen t chang e inth e achievabl e remova l efficienc y o na long - o r short-term

basis . Hig hrelativ e humiditie s ar e presen t inmos t operating system s regardles s o f th e ven t stream

condition s becaus e o f th e wate r remainin g o nth e bedafte r steaming . A s show

ni nFigur e 3-18 , th e workin g capacit y gaine db

y reducin g th e humidit y

i s small . I

nthi s case , reducin g stea m humidit y

woul dprobabl y no t b e cost-effective . I naddition , th e wate r conten t inth e bedprovide s a hea t sin k valuabl e incontrollin g be dtemperature . 3.4. 4 Volumetri c Flowrat e Th e superficia l be dvelocit y fo r a system

change s a s th e volumetri c flo w t o th e system

changes . Th e primar y effec t i s t o chang e th e widt ho f th e mas s transfe r zon e withi nth e bed . A s th e superficia l velocit y increases , the widt ho f th e mas s transfe r zon e als o increase s becaus e th e individua l carbo n pellet s ar e expose dt o th e adsorbat e fo r a shorte r perio do f time , thu s th e quantit y remove da t a give npoin t decreases . Th e effec t o f a wide r mas s transfe r zon e o

nth e shap e o f th e breakthroug hcurv e i s show ninth e to po f Figur e 3-19 . A s show ni nth e bottom

figure , th e time prio r t o breakthroug hi s shortene db

y increase s involumetri c flowrat e becaus e o f th e wide r MTZ . T o illustrat e th e independenc e o f carbo nadsorbe r remova l efficienc y t o short-term

variation s inth e volumetri c flowrate , th e flowrat e an d correspondin g instantaneou s remova l efficiencie s fo r a noperating adsorbe r 3 5 system ar e presente di

nFigur e 3-20 . A s shown , th e flowrat e varie s randoml y durin g th e entir e adsorptio ncycl e whil e th e correspondin g remova l efficiencie s show

littl e variation . Fo r flowrat e variation s fro m 45,00 0 t o 25,00 0 scf m

th e remova l efficienc y varie s les s tha n0. 5 percen t wit hal l efficiencie s bein g wel l abov e 9 9 percent . Sinc e variation s inth e volumetri c flowrat e d o no t affec t th e amoun t o f hee l onth e be da t a give ntime , ther e i s n o B shif t i nth e outle t

3-3 8P.5 2



### E a c o C B k
. * ^ C < u o c o O 

### E C O < u 

### 5 5 o Q

. C O > Constan t Loadin g Increasin g Flowrate



### Distanc e Through Be

d

c 

### g «

•*•• » C C D O c o 

### o

. 2 

### " 3 O Constan t Loadin g Increasin g Flowrate



### Tim e Figur e 3-19
. Effec t o

f Variatio n i n Volumetri c Flowrat e o n th e Shap e o f th e Breakthroug h Curv e

3-3 960,00 0

C O 

### u

tn C D 

## 3
t

_ 

### o 

### u .



### Time, minute s
Figur e 3-20
. Carbo n Adsorbe r Remova l Efficiency wit h Varyin g Flowrat e fo r a

Complet e Adsorptio n Cycl e sP.5 4

concentratio nprio r t o breakthrough , du e t o eithe r long - o r short-term variation s inth e flowrate . Consequently , ther e i s no effec t o nth e long - o r short-term

remova l efficienc y

achievabl e b

y th e system . 3.4. 5 BedFoulin g Thi s sectio ndiscusse s th e effec t o f be dfoulin g a nadsorbe r remova l efficiency . Th e cause s o f be d foulin g wer e previousl y discusse din Section3.2.2 . Be dfoulin g graduall y decrease s workin g capacit y b y tyin g u

p th e activ e adsorptio nsite s inth e micropore s o r blockin g th e pore s whic h preven t adsorbat e molecule s fro m entering . Becaus e th e capacit y o f th e syste

m i s decreased , th e tim e prio r t o breakthroug hi s shortened . A s discusse d previously , thi s ha s n o effec t o na nadsorber' s remova l efficienc y unti l the shortene dlengt ho f th e adsorptio ncycl e begin s t o conflic t wit hth e regeneratio ntime . A t thi s poin t th e carbo nshoul db e replaced . 3 6 Foulin g wil l no t affec t th e outle t concentratio nprio r t o breakthrough . Therefor e ther e wil l b e n o B shif t inth e breakthroug hcurve . Th e reaso ni s tha t foulin g wil l no t affec t th e amoun t o f hee l lef t inth e bed . A s previousl y

discussed , foulin g doe s graduall y reduc e be dworkin g capacity . I

nsome case s th e stea m flow and/o r temperatur e ca nb e increase dt o reduc e th e hee l an

dtherefor e increas e workin g capacit y th e be dages . However , a s previousl y show ni nFigur e 3-9 , th e poin t wil l b e reache dwher e increasin g th e stea

m flow wil l hav e littl e beneficia l effec t o nworkin g capacity . Therefore , eve ni f th e system i s wel l designe d an d operated , a poin t wil l b e approache dwher e ther e i s insufficien t tim e t o regenerat e th e off-lin e be dbefor e th e on-lin e be dreache s breakthrough . A t thi s time , carbo nwil l nee dt o b e replaced . Figur e 3-2 1 present s overal l remova l efficienc y plotte d a s functio no f carbo nbe dag e fo r a system ona ven t stream

containin g cyclohexanone ,

3 7 tetrahydrofuran , methy l ethy l keton e (MEK) , an dtoluene . Bot hcyclohexanon e an dME Kar e know

nt o caus e be dfouling . A s shown , ther e i s onl y a sligh t declin e i nth e remova l efficienc y fro m 99. 6 percen t fo r th e newes t bedt o 99. 4 percen t fo r th e oldes t bed . Thoug hfoulin g o f th e carbo nbe dha s n o affec t o nth e efficienc y o f a n adsorbe r system , i t doe s reduc e be dlife , whic hintur nincrease s th e annua l operatin g cos t o f th e system . Th e foulin g rat e i s affecte db y numerou s

3-4 110 0

99
-

98
-

c o ro u

c a> <o m— xv U J

96
-

9 5 T "

4 —r 1 2 1 6 Legen d Averag e Compositio n o f Recovere d Solven t (W t % ) Cyclohexanon e 4 4 TH F 2 3 ME K1 9 Toluen e 1 4 i 2 0 2 4 2 8 

### Bed Age , week

s



### Figure 3-21
. Carbo n Adsorbe r Remova l Efficienc y a s a Functio n o f Bed Ag e fo r a Keton e Containin g Syste m I T C M C O
C O oP.5 6

factors , bu t th e adsorbat e characteristic s ca nb e considere dth e mos t dramatic . Th e effec t o f severa l solven t blend s o nbe dlif e i s show

ni n Tabl e 3-1 . Fo r th e toluen e an disopropylacetat e (IPA ) applicatio nshown , th e bed s hav e no t ye t bee nchange d afte r si xyear s o f operatio nan d no shortenin g o f th e adsorptio ntime prio r t o breakthroug hha s bee ndetected . Fo r th e toluen e an

dhexan e applicatio nshown , th e be dlif e i s reporte dt o b e 1 0 years . Lifetim e remova l efficiencie s ar e als o show ninTabl e 3-1 . Hig hremova l efficiencie s ar e show neve nfo r stream s containin g hig hconcentration s o f cyclohexanone , a know nfoulin g agent . Facility A ha s a 99. 4 percen t remova l efficienc y

ona si xbe dadsorptio nsystem . Th e be dlif e fo r thi s facilit y i s significantl y

les s tha nth e othe r facilitie s shown . Th e overal l remova l efficienc y

a t Facility

A reflect s th e aggregat e fo r a system wit hbed s at variou s stage s o f life . Th e solven t recovere d a t thi s facility include s approximatel y

4 4 percen t b

y weigh t cyclohexanon e an d1 9 percen t methy l ethy l ketone . Base donth e overal l system remova l efficienc y

fo r thi s system

o f 99. 4 percent , i t ca nb e conclude dtha t al l th e bed s i nth e system ar e achievin g wel l abov e 9 5 percen t removal . 3.4. 6 Channelin g A s discusse dinSectio n3.3 , a carbo nadsorbe r system shoul db e designe d wit hadequat e flow

baffle s an

dprope r steam

distributio nt o preven t channeling . I f channelin g doe s occur , i t wil l caus e elevatio no f th e backgroun doutle t concentratio nove r a cycle , o r a gradua l increas e durin g th e cycle . Fo r system s wit hVO C monitors , thes e increase s wil l b e readil y apparent . I f th e amoun t o f channelin g i s small , th e system ma y stil l be abl e t o retai nth e require dremova l efficiency . I f significan t channelin g occurs , the nadsorbe r remova l efficienc y woul db e significantl y degraded . Ina wel l designe dsystem , channelin g nee dno t occur . Fro m th e perspectiv e o f th e abilit y o f a carbo nadsorbe r t o mee t a specifi c regulator y remova l requiremen t channelin g i s actuall y a malfunctio no f th e system , rathe r tha na facto r causin g inheren t variabilit y inshort-term

efficiency . 3. 5 DELIBERAT E CHANGE S FRO M INITIAL DESIGN

OPERATIN GCONDITION S Thi s sectio ndiscusse s th e effec t o f changin g th e adsorbat e type(s ) an d steamin g conditions . T o asses s th e impac t o f eac hchang e onth e futur e

3-4 3P.5 7



### TABL E 3-1 . REPORTE D BE D LIVE S FORVARIOU S SOLVEN T BLENDS 3 8 

### " 4 1

Faci l


### A

B

C

D it y Solven t blend

44 % Cyclohexanone 0 14 % Methy l Ethy l Keton e 23 % Tetrahydrofura n 19 % Toluen e 50 % Toluen e 50 % Isopropy l Acetat e 95 % Toluen e 5 % Hexan e Methy l Ethy l Keton e Reporte d bed lif e



### _ d

> 6 Year s

1 0 Year s

5 Year s Reporte d remova l

efficienc y

(% )
99. 4



### 98 a

99.5 b

99. 6



### Valu e reporte db

y company . N o dat a wa s provide dt o verify . Estimation : Assume daverag e inle t loadin g wa s mi d rang e indesig n specificatio nrange , an d outle t loadin g wa s th e reporte dvalue . c 

### Actua l solven t blend s a t thi s facilit y vary . Th e value s ar e typica l o f the tota l solven t recovereddaily . Th e specifi c be d lif e a t thi s facilit y i s confidentia l busines s information . However , i t i s significantl y lowe r tha nth e othe r value s shown . Thi s reduce d be dlif e i s believe dt o b e a t leas t partiall y du e t o th e presenc e o f cyclohexanon e an

d methy l ethy l ketone .

3-4 4P.5 8

operatio nan

dperformanc e o f th e adsorbe r system , th e logi c associate dwit h th e initia l specificatio no f eac hdesig nparamete r i s discussed . 3.5. 1 Adsorbat e Th e concentratio nan

dtyp e o f organi c ar e key factor s inth e desig no f a carbo nadsorptio nsystem . Th e adsorptio ncharacteristic s o f eac hcompoun dar e assesse db

y usin g thei r physica l propertie s data , suc has : polarity ; refractiv e index ; boilin g point ; molecula r weight ; an dsolubilit y

inwater . Nonpola r compound s an dcompound s wit hhig hrefractiv e indice s tend t o be 4 2 adsorbe dmor e readily . Hig hvapo r pressure/lo w boilin g poin t adsorbate s an d 4 3 low molecula r weigh t compound s adsor bles s readily . Compound s wit h molecula r weight s greate r tha n14 2 adsor breadil y bu t ar e difficul t t o 4 4 desorb . I f th e adsorbat e i s wate r soluble , wate r lef t a s condensat e inth e bed 4 5 afte r steamin g an

dcoolin g ca ncontai nadsorbate . Whe nth e adsorbe r i s brough t on-line , th e wate r an dadsorbat e wil l evaporat e fro m th e beddurin g th e firs t par t o f th e adsorptio ncycle , slightl y increasin g th e initia l outle t concentratio nfo r a brie f time unti l th e concentratio nfall s rapidl y t o a norma l baselin e value . Th e propertie s an

dadsorptio ncharacteristic s affec t bot hth e desig nan d operatin g conditions . I f th e fee dstream i s changed , th e adsorbe r system mus t b e re-evaluated . I f i t ca naccommodat e th e ne w feed , ther e wil l be no effec t onth e achievabl e remova l efficiency ; althoug hon-lin e adsorptio ntime an d steamin g requirement s ma y nee dt o b e changed . I f timer s ar e use da s th e trigge r mechanisms , th e ne w workin g capacit y

o f th e bed s mus t b e determined . Usin g thi s workin g capacit y an da maximu

m inle t loading , th e appropriat e ne w adsorptio ntim e ca nb e determine ds o tha t th e timer s ca nb e rese t fo r th e new operatin g conditions . Changin g th e adsorbat e ca nals o affec t th e desorptio ncycle . Th e relationshi pbetwee nsteam usag e an

dworkin g capacit y

wa s previousl y

show nfo r thre e differen t compound s inFigur e 3-9 . A s ca nb e seen , i f th e adsorbat e blen di s changed , th e optimu m stea m requirement s ma y

als o change . 3.5. 2 Steamin g Condition s A s previousl y

discussed , steamin g requirement s ar e determine da s par t o f th e initia l system

design . Variable s whic hmus t b e considere dar e th e

3-4 5P.5 9

steamin g temperature , duration , an drate . Generally , stea m temperatur e i s fixe dwit ha give nplant . Fo r thi s reason , th e effec t o f temperatur e i s no t discussed . Th e amoun t o f stea m require di s determine d b y th e require dworkin g capacity . Onc e th e initia l desig ni s set , a s long a s th e amoun t o f stea m use d pe r desorptio ncycl e remain s constant , th e availabl e workin g capacit y wil l remai nconstan t assumin g no foulin g o r othe r degradatio no f th e carbo nbed . Inactua l application , however , th e carbon' s tota l absorptio ncapacit y graduall y

decrease s ove r time du e t o fouling . I f th e operato r desire s t o maintai nth e same breakthroug htime , stea m us e pe r desorptio ncycl e mus t be graduall y

increased . (Alternately , i f sufficien t standby time i s available , th e lengt ho f th e adsorptio ncycl e ca nb e graduall y decrease da s previousl y discussed. ) A t some poin t th e amoun t o f stea m require dpe r desorptio ncycl e become s s o grea t tha t eithe r ther e i s insufficien t time t o complet e desorptio n befor e breakthroug ho f th e on-lin e bed , o r th e cos t o f stea m become s to o great . A t thi s poin t th e carbo nmus t b e replaced . Althoug hsteamin g amoun t i s importan t i nth e desorptio nprocess , duratio n i s als o a consideration . Inorde r t o remov e th e adsorbate , sufficien t tim e at th e steamin g temperatur e i s required . Thi s i s t o allow fo r diffusio no f the adsorbat e ou t o f th e pore s an dou t o f th e carbo nparticle . Withou t sufficien t time , increasin g th e flow o f stea

m wil l no t remov e th e adsorbat e fro m dee p withi nth e pore s o f th e carbon . 3. 6 PERFORMANC E INFORMATION ON INDUSTRIA L ADSORBER S Availabl e dat a concernin g th e abilit y o f carbo nadsorbe r system s t o achiev e 9 5 percen t remova l efficiencie s ar e summarize dinthi s section . Dat a fro m performanc e test s sponsore db y EPA' s Offic e o f Researc han dDevelopmen t (ORD) , thre e tes t program s sponsore db y EPA' s Emission s Standard s Divisio n (ESD) , an

dindustr y

ar e use dt o suppor t th e conclusion s reached . Fo r eac ho f th e tests , th e desig nparameters , operatin g condition s durin g testing , an d tes t informatio nan

dresult s ar e given . A compariso nbetwee ndesig nan d operatin g informatio ni s the nuse dt o evaluat e i f a give nsystem wa s operate d withi ndesig nlimit s durin g testing . Dat a source s alon g wit hth e sit e code s an dtes t numberin g scheme use di n th e presentatio nar e discusse dinSectio n3.6.1 . InSectio n3.6. 2 th e

3-4 6P.6 0

adsorbe r system

operatio ni s discusse d wit hrespec t t o th e remova l efficiencie s achieve d a t a give nsite . Specifically , poo r system operatin g procedure s whic hwer e identifie d ar e explained . Finally , i nSectio n3. 6 th e conclusion s reache d regardin g adsorbe r performanc e ar e presented . 3.6. 1 Dat a Source s A summar y o f th e availabl e carbo nadsorbe r emission s tes t result s i s give ni nTabl e 3-2 . Averag e overal l remova l efficiencies , desig nan d actua l operatin g conditions , an d testin g informatio nar e give nfo r eac ho f 1 2 sites . Emission s tes t dat a wer e availabl e fo r 1 1 o f th e 1 2 sites . Th e twelft h reporte d efficiencies , bu t provide d n o supportin g data . Fo r eac ho f th e test s 1-15 , a uniqu e tes t numbe r i s reported . Repea t test s wer e don e a t 4 o f th e twelv e sites . Tabl e 3- 3 present s individua l averag e be d remova l efficiencie s fo r severa l o f thes e sites . Test s 1-1 0 wer e performanc e test s performe d a s par t o f a nEPA/OR D stud

y 4 6 o f carbo nadsorbe r performanc e invariou s industries . Th e manufacturin g processe s include d ar e rubberize d fabric , magneti c tape , flexibl e packaging , an d rotogravur e printing . Tes t 6 o f thi s stud y wa s no t presente d fo r reason s discusse d inSectio n3.6.2 . Si xo f th e 1 0 test s wer e conducte d inearl y 1982 . Th e fou r follow-u p test s wer e performe d on e t o tw o year s afte r th e initia l test . Test s 11-1 3 wer e performe d a s par t o f EPA/ES D performanc e evaluation s 47-4 9 a t thre e specifi c sites . Result s fro m Test s 1 4 an

d 1 5 wer e provide d b y

. . a. 50,5 1 industry . ' Test s 1-1 3 wer e conducte d inaccordanc e wit happrove d EPA methods . Inle t
an d outle t concentration s wer e measure d semicontinuousl y wit hflame ionizatio n detecto r tota l hydrocarbo ninstrumentatio na s describe d i nEPA Metho d 25A . Volumetri c flow

rate s wer e measure d accordin g t o EPA Method s 1 an

d 2 . Al l test s wer e verifie d b y EPA-specifie d qualit y assurance/qualit y

contro l procedures . Test s 1 4 an

d 1 5 wer e performe d i naccordanc e wit hEPA Method s 1,2 , an d 25 . Metho d 2 5 differ s fro m Metho d 25 A

intha t integrate d ba g sample s ar e take nan d th e concentratio no f th e ga s withi nth e ba g i s use d t o determin e the remova l efficienc y

ove r th e samplin g period . Althoug hthi s metho d doe s no t giv e th e semicontinuou s dat a provide d b y Metho d 25A , i t provide s a mean s fo r accuratel y

assessin g th e averag e remova l efficienc y ove r th e samplin g period .

3-4 7TABL E 3-2 . PERFORMANC E TES T DAT A FO R CARBON

ADSORPTIO N

SYSTEM S

Desig n Parameter s Condition s Durin g Tes t

Tes t Flowrat e No . Sit e (SCFM ) Component s i n inle t stream Adsorbat e Stea m Loadin g Temperatur e Flo w Flowrat e Component s i n (lb/hr ) (F) (lb/hr) (SCFM ) Inle t Stream 3 Averag e Adsorbat e Steam Be d Remova l Loadin g Temperatur e Flo w Ag e Efficienc y (lb/hr) (F) (lb/hr ) (years ) (X )

C J I -p . C O 1 A 11,20 0

2 B 12,70 0

3 B 12,70 0

4 C 23,00 0

5 D 22,00 0

7 E 11,10 0
8 E 11,10 0
9 F 80,00 0

1 0 F 80,00 0 ME K- 60 Z Toluen e - 4 0

TH F - 50 Z Toluen e - 50 Z

TH F - 50 Z Toluen e - 50 %

THF , Toluene , MEK , MIBK , Cyclohexanon e

1 1 C N R NR

1 2 H N R N R
1 3 I 75,00 0 N R 57 5

14 0

14 0

60 0

N R

N R

N R

1 4

1 5 J

K

L 10,00 0 - 83,70 0

24,00 0
28,00 0 ME K- 20-50 Z

Cyclohexanon e - TH F - 5-25 Z Toluen e - 5-25 Z ME K- 100 Z
Toluen e - 95 Z Hexan e - 5 Z 2 0 -50 Z 18 0 - 2,80 0

1,20 0
86 0 - 1,07 0 9 5

9 0

9 0

8 5 2,37 5 11,40 0 ME K- 100 Z

Hexan e - 100 Z
Toluen e - 100 Z
Toluen e - 100 Z
Toluen e - 60 Z IPAC - 40 X
Toluen e - 60 X IPA C - 40 X 1,30 0
20 4
20 4
81 0

81 0 9 5

10 0
10 0
12 0

12 0

N R

N R

NR

<20 0

NR
12 0 90 0 9,80 0

90 0 9,50 0

2,40 0 19,80 0

4,13 0 17,70 0
1,17 0 9,10 0
1,17 0 7,80 0
1,18 0 33,40 0

1,18 0 33,90 0

N R 8,40 0 TH F - 50 Z

Toluen e =50 %

TH F - 75 Z Toluen e - 25 X

THF , Toluene , MEK , MIBK , Cyclohexanon e

Hexan e - 100 Z
Toluen e - 100 Z
Toluen e - 100 Z
Toluen e - 60 Z IPA C - 40 Z
Toluen e - 60 Z IPA C - 40 Z

ME K- 95 Z MIBK , Toluen e - 5 Z 28 4 9 4

19 5 7 4

14 0 9 0

1,26 0 8 1

89 2 6 7

3,55 0 N R 2,41 0

60 0

86 0

3,30 0 0. 4 84. 9

99. 7

3. 8 95. 3

2,90 0 0. 4 94. 8

35 5

c 24 9 10 1
929 ° 8 9
10 4
13 2
9 1 3,20 0

3,00 0
2,80 0
3,40 0 3

5
6. 5
0. 2 99. 1
97. 6
94. 6
97. 5 8, h

1. 6 97. 8

NR N R 98. 9

98 J N R

N R

2,00 0

1,75 0
3,00 0 48,80 0

61,20 0

60,000 - 70,00 0

24,00 0
28,00 0 Toluen e - 10O Z

Toluen e - 30 Z Xylen e - 4 Z Lacto l Spirit s - 66 Z

THF - 5,41 0 (l b pe r day ) Toluen e - 3,21 0 MEK- 4,48 0 Cyclohexanon e - 10,50 0 MEK- 100 Z

H R 98 0
1,27 9

NR

402 k

N R 9 4
10 0

12 0

8 3
12 0 11,00 0

N R

12,00 0

1,75 0
3,00 0 N R

N R

Varta l

2
N/A ] 95. 8

99. 6
99. 5TABL E 3-2 . PERFORMANC E TES T DAT A FO R CARBO N

ADSORPTIO N

SYSTEM S (Continued )

C O I V O *ME K«* - Methy l ethy l ketone : TH F • » Tetrahydrofuran ; MIB K= Methy l isobuty l ketone ; IPAC = Isopropy l acetate . Th e lo w remova l efficienc y wa s a resul t o f adsorbat e blen d bein g differen t fro m system

desig n specifications , cocurren t steaming , coolin g wit hadsorbat e lade n air , an d malfunctio n i n condense r system . Solven t loadin g wa s abov e desig n specificatio n durin g test . ttemova l efficienc y wa s reduce d du e t o reductio n l n desorptio n steam temperature , chang e i n solvents , an d elevate d adsorbe r inle t temperature . Remova l efficienc y wa s likel y

reduce d du e t o hig hadsorbat e loadin g causin g prematur e syste m breakthrough . Inle t stream

temperatur e wa s abov e desig n specification s durin g test . Dat a fro

m be d 2 wer e no t include d i n averag e becaus e a steam valv e lea k cause d a sever e reductio n i n be d capacity . Overal l syste m

remova l efficienc y wa s reduce d du e t o th e inle t stream temperatur e bein g abov e design . N R • = Dat a no t reported . Remova l efficienc y i s tim e weighte d accordin g t o lengt ho f tim e Individua l line s wer e operating . l r Inle t adsorbat e loadin g expresse d a s 6 7 l bC /hr . T o conver t t o loadin g i n term s o f l bMEK/h r nee d t o multipl y by 6 (M W ME K= 72/M

W C -12) . l No t applicable . Thes e dat a ar e no t from a specifi c performanc e test . Remova l efficienc y wa s calculate d fro m inle t an d outle t concentration s reporte d b y th e facility . Continuou s average , includin g distillatio n steam . "Th e averag e o f th e remova l efficienc y o f th e individua l beds .P.6 3

TABL E 3-3
. PERFORMANC E TES T DATAFO R CARBO NADSORPTIO NSYSTEMS 53 " 5 5 ONAPE R BED BASI S

Dat a collectio n Remova l Tes t numbe r Be d designatio n tim e perio d efficiency , %
1 ANA b87.2 a B N A78.9 a 2 1 N A99. 6 2 N A99. 8 3 N A99. 8 3 1 N A97. 3 2 N A92. 7 3 N A95. 9 4 I A70 5 min

. 94. 0
I B 82 6 min

. 94. 0 I B 38 2 min

. 94.3 r . I B 28 0 min

. 89.2 c , a 2 A24 7 min

. 92. 9 2 A27 9 min

. 91. 3 2 B 10 5 min

. 88.9 d ' e 2 B 24 7 min

. 95. 5 3 A12 8 min

. 96. 2 3 A27 1 min

. 97. 7 3 A64 7 min

. 96. 6 3 B 89 8 min

. 98. 0 3 B 78 1 min

. 96. 2 5 1 45 1 min

. 99. 4 2 38 8 min

. 99. 3 2 50 7 min

. 99. 0 2 22 8 min

. 99.4 e 3 29 5 min

. 98.9 f AN A97. 0 B N A97. 6 C N A98. 3

(continued )

3-5 0P.6 4



### TABL E 3-3 . (Continued )

Tes t numbe r 

### 8

9

1 0

1 1 Be

d designatio n


### A B C 1- 1 1- 1 1- 1 1- 1 1- 1 1- 1 1- 2 1- 2 1- 2 1- 2 1- 3 1- 3 1- 3 1- 1 1- 2 1- 3 1 1 1 1 1 3 3 3 3 3 Dat a collectio n

tim e perio d


### N A N A N A 7. 6 hrs . 9. 1 hrs . 8. 6 hrs . 8. 1 hrs . 5. 5 hrs . 6. 8 hrs . 

### 8. 5 9. 4 8. 2 6. 0 8. 1 6. 4 7. 4 N A N A N A N A N A N A N A N A N A N A N A N A N A Remova l

efficiency , %
91. 4 91. 4 97. 8 98. 0 97. 4 97. 8 96. 6 97. 3 97. 6 97. 9 96. 8 97. 0 97. 6 97. 8 97. 5 98. 1 97. 9 98. 1 97. 5 99. 8 95. 5 97. 7 97. 8 98. 9 99. 4 96. 4 98. 5 98. 8 98. 7



### Dat a ar e fro

m on e cycle ; overal l system efficienc y

wa s 84. 9 percent . b 

### N A = No t available . c 

### 0nl y on e coatin g lin e i noperation . Collecte ddurin g startu po f on e o f th e lines . e 

### Coatin g proces s unsteady durin g thi s period . No t representativ e o f norma l operation ; system returnin g t o steady-stat e afte r al l bed s o

nadsorption . 3-5 1P.6 5

Sit e L supplie d n o detaile d informatio ns o onl y th e reporte d remova l 5 2 efficienc y

i s presented . 3.6. 2 Remova l Efficienc y Dat a fo r Performanc e Test s Th e overal l remova l efficiencie s presente d inTabl e 3- 2 rang e fro m 84. 9 t o 99. 7 percen t fo r a variet y o f adsorbate s includin g MEK , toluene , THF , MIBK , cyclohexanone , hexane , an d IPAC . Ona pe r bed basis , th e rang e o f
remova l efficiencie s i s 52. 3 t o 99. 8 percent . A s shown , th e bed age s associate d wit hth e adsorber s teste d rang e fro m 3 t o 7 8 months . Th e overal l remova l efficienc y o f 84. 9 percen t reporte d fo r Tes t 1 i s the resul t o f bot hoperatin g outsid e o f th e origina l desig nrang e an d poo r operatio ndurin g th e test . Th e system wa s designe d t o recove r a nadsorbat e blend consistin g o f 6 0 percen t methy l ethy l keton e an d 4 0 percen t toluene . A t th e time o f th e test , th e organi c fee d wa s 10 0 percen t methy l ethy l ketone . A s discusse d i nSectio n3.5.1 , switchin g adsorbat e blend s ca nhav e a detrimenta l effec t onremova l efficiency . Inaddition , severa l operatin g practice s a t thi s sit e ma y hav e contribute d t o th e reduce d contro l efficiency . Thes e includ e cocurren t steamin g o f th e bed , cocurren t coolin g o f th e bed wit h th e adsorbat e lade nstream , an d operatin g wit ha malfunctionin g stea m condenser . Cocurren t steamin g leave s mor e residua l solven t a t th e bed outle t tha n countercurren t steaming , thu s increasin g th e outle t concentratio nwhe nth e be d i s brough t on-line . Coolin g th e bed wit hth e adsorbat e lade nven t strea m furthe r aggravate s thi s proble m becaus e i t allow s adsorbat e lade nai r t o ente r th e be d whe nth e system workin g capacit y

i s a t it s lowest . Thi s allow s adsorbat e t o sprea d dow nth e bed muc hfurthe r tha ni f th e system i s operate d correctly . Fo r reason s whic hhav e bee ndiscusse d inSectio n3.4. 1 thi s cause d th e system

t o b e mor e sensitiv e t o variation s inth e operatin g temperature . Th e fina l proble m

associate d wit hthi s system wa s a malfunctio ni nth e condense r system . Th e system wa s no t coolin g th e desorbat e strea m sufficiently . Sinc e th e stea m fro m th e condense r wa s recycle d t o th e on-lin e bed , unusuall y

hig hamount s o f solven t wer e allowe d t o ente r th e bed fro m th e recycl e stream . Thi s additiona l solven t loadin g led t o prematur e breakthrough .

3-5 2P.6 6

Insummary , thes e problem s woul d indicat e tha t thi s system wa s no t wel l designe d an

d wa s poorl y

operated . It s remova l efficienc y i s no t representativ e o f a wel l designe d an d operate d system . I t shoul d b e note d tha t severa l o f th e problem s woul d hav e bee ndiscovere d a s par t o f norma l operatio ni f th e system had use d continuou s outle t monitors . Th e averag e overal l remova l efficienc y presente d fo r Tes t 2 i s 99. 7 percent . Th e individua l be d efficiencie s rang e fro m 99. 6 t o 99. 8 percent . Th e solven t blend fo r thi s system wa s 5 0 percen t toluen e an d 5 0 percen t tetrahydrofuran , an d al l o f th e operatin g condition s wer e withi n desig nspecification s wit hth e exceptio no f th e loadin g rate . Th e desig n specificatio nwa s 14 0 lb/hr , bu t th e actua l loadin g rat e wa s 19 5 lb/hr . Tes t 3 i s a follow-u p tes t a t sit e B . Fo r thi s test , th e averag e system overal l remova l efficienc y wa s 95. 3 percen t wit hth e individua l bed efficiencie s rangin g fro m 92. 7 t o 97. 3 percent . Al l o f th e bed s had lowe r remova l efficiencie s tha ni nth e initia l test , Tes t 2 . Th e reduce d remova l efficienc y

durin g th e second tes t wa s attribute d t o th e followin g i nth e 5 7 tes t report :

• Increase d carbo nage ;

• lowe r regeneratio nstea m temperature ;

• highe r SLA

inle t temperature ; an d

• chang e i nsolven t formulatio nt o 7 5 tetrahydrofura nan d 2 5 percen t toluene . 5 8 Figur e 3-2 2 present s a typica l outle t concentratio ncurv e fo r thi s test . Durin g th e initia l tes t (Tes t 2) , th e typica l outle t concentratio nhad a n initia l spik e an

d the ndecrease d t o approximatel y 1 pp m fo r th e remainde r adsorptio ncycle . However , durin g Tes t 3 , th e outle t concentratio nwa s muc h highe r an

d a nupwar d trend indicatin g th e beginnin g o f breakthroug hcanbe C Q see na t th e en

d o f th e cycle . Thi s resul t woul d b e expecte d du e t o th e factor s show

nabove . I f th e desorptio nan d adsorptio ncycle s ha d bee n adjuste d t o accoun t fo r th e change s i nSLA inle t temperature , solven t

3-5 3P.6 7

LL
. I
c © O r- > 

### E a. o. c o

* f C O
m-a c 0 ) o c o 

## o o O > 1,500
- 1,400
- 1,30 0 1,20 0 1,100
- 1,000
- 900 - 80 0 700 -

10
- 0 

### Adsorptio n

Averag e C

in =118 0 ppm

v 

# 1

Averag e Cou , = 25 ppm v
1 0 2 0 3 0 4 0 

## "io " 6 0



### Tim e (min.)

Figur e 3-22
. Inlet/Outle t Concentratio n Curv e fo r Tes t 3

3-5 4P.6 8

composition , an

dregeneratio nstea

m temperature , an

dcarbo nag e the nth e performanc e durin g Tes t 3 shoul dhav e bee nsimila r t o th e Tes t 2 performance . However , eve nthoug hthi s system di dsho

w reduce defficienc y

inTes t 3 , th e averag e system

efficienc y

wa s ove r 9 5 percent , whic hwoul d b e sufficien t t o mee t th e 9 5 percen t remova l efficienc y requiremen t inth e propose dmagneti c tape s regulation . Th e adsorbat e blendconcentration s fo r Tes t 4 ar e no t specified , bu t th e blendinclude dtetrahydrofuran , toluene , methy l ethy l ketone , methy l isobuty l ketone , an

dcyclohexanone . Th e averag e overal l remova l efficienc y fo r Tes t 4 i s 94. 8 percent . Individua l be dremova l efficiencie s range dbetwee n89. 2 an d 98. 0 percent . Th e averag e loadin g fo r th e tes t perio dwa s 1,26 0 lb/h r whic h i s ove r twic e th e desig nleve l o f 60 0 lb/hr . I f th e adsorptio ntime hadbee n shortene dt o accoun t fo r th e increase dloadin g (a s discusse dinSectio n3.4) , remova l efficiencie s fo r al l bed s woul dhav e bee nhighe r an da s discusse di

n Sectio n3.3.3 , th e variabilit y woul db e less . Hexan e i s th e onl y

adsorbat e a t Tes t 5 . Th e overal l remova l efficienc y show nfo r thi s tes t perio di s 99. 1 percen t wit hindividua l be defficiencie s rangin g betwee n98. 9 an d99. 4 percent . Al l o f th e operatin g condition s wer e withi ndesig nspecifications . Th e follo w

uptes t a t thi s sit e wa s Tes t 6 . Inthi s test , a nextremel y lo w remova l efficienc y

wa s achieve ddu e t o a leakin g stea m valve . Excursion s inth e outle t concentratio nwer e show nt o coincid e wit hth e steamin g cycl e fo r th e off-lin e bed . Inthi s system , th e stea m flow i s cocurrent , inth e sam e directio na s th e ai r flow durin g adsorption . Consequently , th e stea m lea k allowe dth e solven t lade nsteam fro m th e off-lin e be dt o ente r th e outle t stream o f th e onlin e beds . Thi s resulte di nfals e reading s a t th e adsorbe r outlet . Fo r thi s reaso nn o dat a fro m thi s tes t wer e include d inthi s report . Th e result s show

nfo r Tes t 7 ar e fo r a singl e componen t system inwhic h toluen e i s recovered . Th e overal l remova l efficienc y fo r thi s tes t i s 97. 6 percen t eve nthroug hbot hth e inle t temperatur e an dloadin g rat e wer e slightl y abov e desig nspecifications . Th e individua l be dremova l efficiencie s wer e betwee n97. 0 an d98. 3 percent . Th e follo w

upt o Tes t 7 i s Tes t 8 . Toluen e wa s als o th e onl y adsorbat e fo r thi s test . Th e remova l efficienc y fo r be d2 i s no t include dinth e

3-5 5P.6 9

averag e remova l efficienc y o f 94. 6 percen t whic hi s show nfo r thi s test . (Tabl e 3-2 ) A

stea m valv e lea k allowe d stea m t o lea k int o bed 2 raisin g th e temperatur e significantly , an d severel y

reducin g th e workin g capacity . A s i n Tes t 6 , th e outle t concentratio npeak s wer e show nt o coincid e wit hth e desorptio nperio d o f th e off-lin e bed . Sinc e th e dat a fo r thi s bed ar e no t representative , the y wer e no t included . Th e lowe r remova l efficienc y fo r th e othe r tw

o bed s i s th e resul t o f tw o relate d problems . A malfunctionin g inle t ai r coole r allowe d th e inle t temperatur e t o ris e 32° F abov e th e desig nmaximu m an d als o a time r occasionall y malfunctioned . Onc e again , th e us e o f continuou s outle t monitor s inth e operatio no f thi s system woul d hav e helpe d t o uncove r th e malfunctio ninoperation . Test s 9 an

d 1 0 wer e bot hconducte d a t sit e F wit hanadsorbat e blend o f 6 0 percen t toluen e an d 4 0 percen t isopropy l acetate . Th e overal l remova l efficiencie s fo r thes e tw o test s wer e 97. 5 percen t an d 97. 8 percent , respectively . Th e individua l be d remova l efficiencie s wer e 96. 8 t o 98. 1 percent . Thes e remova l efficiencie s agre e wel l wit hwha t woul d be expecte d fo r th e tw

o set s o f operatin g conditions . Inbot htests , th e inle t adsorbat e loadin g wa s abov e th e desig nspecification s o f 81 0 lb/hr . Al l o f th e othe r operatin g condition s wer e withi ndesig nspecification s durin g bot h tests . N o desig nparameter s o r individua l bed remova l efficiencie s wer e availabl e fo r Test s 11 , 12 , an d 13 . Therefore , i t wa s no t possibl e t o asses s th e system

operatio ni nterm s o f design . Th e adsorbate s fo r Tes t 1 1 wer e methy l ethy l ketone , methy l isobuty l ketone , an d toluene . Th e overal l remova l efficienc y

show nfo r Tes t 1 1 i s 98. 9 percent . Fo r Tes t 1 2 th e overal l remova l efficienc y

wa s 9 8 percen t fo r a adsorbat e o f 10 0 percen t toluene . Th e adsorbat e mixtur e fo r Tes t 1 3 wa s 3 0 percen t toluene , 4 percen t xylene , an d 6 6 percen t lacto l spirits , an d th e overal l remova l efficienc y i s 95. 8 percent . Th e overal l remova l efficienc y show nfo r Tes t 1 4 i s 99. 4 percent . Th e averag e compositio no f th e recovere d VO C a t thi s sit e i s a s follows : 4 4 percen t cyclohexanone , 2 3 percen t tetrahydrofuran , 1 9 percen t methy l ethy l ketone , an

d 1 4 percen t toluene . Al l o f th e operatin g condition s show nfo r thi s tes t ar e withi nth e desig nlimits . InTes t 15 , th e adsorbat e i s

3-5 6P.7 0

10 0 percen t methy l ethy l keton e an d th e overal l remova l efficienc y i s 99. 6 percent . Non e o f th e operatin g condition s a t thi s sit e wer e outsid e o f th e desig ncondition s reported . No actua l tes t dat a ar e availabl e fo r sit e L , bu t th e overal l remova l efficienc y

wa s reporte d b

y th e company

99. 5 percent . Th e adsorbat e blend a t thi s sit e wa s 9 5 percen t toluen e an d 5 percen t hexane . Th e performanc e tes t dat a show ni nthi s sectio ngenerall y show remova l efficiencie s abov e 9 5 percent . Fo r case s wher e th e remova l efficienc y wa s below 9 5 percent , correctabl e problem s wer e identifie d whic hwer e th e caus e o f th e lowe r remova l efficiencies . I t shoul d b e note d tha t thes e performanc e tes t dat a ar e fairl y

shor t duratio nrangin g fro m les s tha n2 hour s u p t o 1 5 hours . I f th e time period s o f startu p an d system

malfunction s ar e no t considered , th e remova l efficiencie s ar e fairl y consisten t wit hlittl e variabilit y

fro m be d t o bed . 3.6. 3 Continuou s Remova l Efficienc y Dat a Continuou s efficienc y dat a ar e availabl e fro m tw o sites . Thes e dat a ar e presente d t o show

a short-term

efficienc y

variability . Th e dat a encompas s a relativel y

broa d rang e o f solven t blends , adsorbat e loadings , flowrates , an d inle t temperatures . Figure s 3-2 3 an

d 3-2 4 presen t continuou s inle t an d outle t concentratio n an d remova l efficienc y dat a versu s time fo r tw o tes t run s fro

m sit e Gi

n Tabl e 3-2 . A s show

ninth e figures , th e inle t concentration s var y significantl y

throughou t th e respectiv e testin g periods . However , th e outle t concentration s remai nfairl y consisten t regardles s o f th e inle t concentrations , an

d ar e almos t alway s les s tha n1 0 ppm . Th e remova l efficiencie s ar e als o fairl y consisten t an

d ar e generall y

abov e 9 5 percent . Th e onl y tim e th e remova l efficienc y i s below

9 5 percen t i s whe nth e inle t concentratio nfall s below abou t 5 0 ppm . Thi s i s expecte d sinc e a s previousl y discussed , th e outle t concentratio ni s independen t o f th e inle t concentration . Therefore , i f th e inle t concentratio ni s allowe d t o fal l below th e desig n value , th e instantaneou s remova l efficienc y ca nals o decreas e below desig n levels .

3-5 7P.7 1

M O

SO O - | 70 0 - a yyf 60 0 - O aa O 90 0 k

. aa c
•40 0 - U c 

# I - 

# rV ~

y

9:0 0 10:0 0 11:0 0

E a a c o S
u e o o

3 o 4 0 -

3 0 -

2 0 -

1 0 -

9:0 0 —.—*-" ~ Tim * In M Concentratio n va . TIm a

, , » IO-O O ii-o o 12*0 0

»«• % K > , u c • uffi u o o E o c s a -

9 0 - 8 / - s a - S S - 9 4 - S 3 - S 3 - S I - 9 0 - a a - a a - a » - a a - a s -

• 4 - U - S 3 - S I - a o - Tln w Outta l Concentratio n va . TIm a 

# ^ n

- - . 1 ——+—» — 

## u

_ ^ to o 1041 0 11:0 0
Nanova l Efficienc y va . Tan a Figur e 3-23 . GT RTes t Numbe r 5 Continuou s Inlet/Outle t VO C Concentratio n

Dat a an d Remova l Efficienc y 3-5 8- » SO O a a
c o a v . aa C e u c o u J0 0 - 

### "

U 

# h

/ 

# l 

# i

i — *

- 9:0 0 10:0 0 11:0 0 12:0 0 1 3 0 0 1 4 0 0 15:0 0 18:0 0 Tim e Inle t Concentratio n vs . Tim e

E a a mf C o at O i

. ma C e u c 0 o e aa 3 o to o
9 0

8 0

7 0

8 0
S O
4 0

3 0
2 0

1 0
0

8:0 0 11-0 0 12-0 0 13:0 0 14:0 0 18:0 0 18:0 0
Mmova l Effldenc-t

f va. TIm a Figur e 3-24 . GT RTes t Numbe r 6 Continuou s Inlet/Outle t VO C Concentratio n

Dat a an d Remova l Efficienc y

3-5 9P.7 3

Inle t an d outle t concentration s an d instantaneou s an

d cumulativ e remova l efficiencie s fo r si xadsorbe r bed s a t sit e J ar e presente d inFigure s 3-25 a throug h3-25j . Th e continuou s dat a show nwer e obtaine d a t th e reques t o f EP A an d ar e typica l o f norma l facilit y operation . A s previousl y discussed , th e solven t blend a t thi s facilit y range s fro

m 20-2 5 weigh t percen t cyclohexanon e an d 20-5 0 weigh t percen t methy l ethy l keton e (MEK) . Bot hcyclohexanon e an d ME Khav e bee nidentifie d a s chemical s whic hreac t o ncarbo nt o caus e fouling . Th e dat a ar e continuou s monito r readout s fo r eac ho f th e si xcarbo nbed s whic h compris e th e complet e system . Th e inle t concentration s var y betwee nabou t 2,00 0 pp m an d 3,00 0 ppm , wit hadsorber s # 1 an d # 2 havin g th e highes t inle t concentrations . Th e continuou s outle t concentration s fro m al l 6 adsorber s ar e below 5 0 ppm . O f particula r not e i s th e fac t tha t bot hth e instantaneou s remova l efficienc y

an d th e cumulativ e efficienc y ove r th e entir e monitorin g perio d fo r al l adsorber s ar e abov e 98. 5 percent . Th e instantaneou s remova l efficiencie s o f th e newes t bed range d fro m 99. 3 t o 99. 8 percent . Th e efficienc y o f th e oldes t bed range d fro m 99. 9 t o 98. 5 percent . On e reaso nth e remova l efficiencie s o f th e bed s stay wel l abov e 9 5 percen t i s tha t th e bed s ar e change d frequently . Thi s facilit y coul d operat e th e bed s unti l thei r remova l efficienc y ha s reache d 9 5 percent , bu t ha s chose nno t b e d o s o t o avoi d operatio nproblem s whic hcoul d caus e overal l remova l efficienc y t o fal l below

th e desire d value . Th e dat a fro

m thes e two site s indicat e tha t th e 9 5 percen t remova l efficienc y

ca nb e maintaine d continuousl y i f th e carbo nabsorbe r i s properl y designed , operate d withi nit s desig nspecifications , an d wel l maintained . 3. 7 CONCLUSION S REGARDINGCARBO N ADSORBE RPERFORMANC E Th e dat a presente d inSectio n3. 6 demonstrat e tha t properl y designe d an

d operate d carbo nadsorptio nsystem s ca nachiev e 9 5 percen t remova l o na continuou s basis . Thi s remova l efficienc y i s show

nfo r numerou s solven t blend s an

d be d ages . Greate r tha n9 5 percen t remova l efficienc y i s show

nfo r stream s tha t contai nmixture s o f ketone s tha t includ e cyclohexanone , an d fo r whic hclaim s hav e bee nmad e tha t 9 5 percen t i s no t achievabl e usin g carbo n

3-6 0P.7 4

E a a ._• z o

z U i u z o u

is 0 

## t
U l 40 0

35 0 -

30 0 -

25 0 I I O O 20 0 -

15 0 -

10 0 -

5 0 -a- &

V-o- s » » •» s » »--»•-*->»•»• , •»»•»•»••«»•»- •

- i i •i i I I i ••••• — »»»•> » o -»-•»- < 2 0 4 0

O Inle t (xl/10 ) TIM E (min ) Outle t Figur e 3-25a . Inle t an dOutle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 1

Inatantonaou s TIM E (min ) Cummutative Figur e 3-25b . Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Time fo r Adsorbe r # 1

3-6 1E

a a •** z o 

# 1
. z U l o z o u 40 0

35 0 -

30 0

25 0 -

20 0 -

15 0 -

10 0

Outle t Figur e 3-25c . Inle t an d Outle t Concentratio nVersu s Cycl e Tim e fo r Adsorbe r # 2

o a

z u G 

# E

u i

Instantoneou s TIM E (min ) Cummutative Figur e 3-25d . Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Tim

e fo r Adsorbe r # 2 3-6 2P.7 6

E a a z o 

# 1
. z U l o z o u

a 

# s o I t U l 30 0 - 28 0 - 26 0 - 24 0 - 22 0 - j 20 0 - 18 0 - 16 0 - 14 0 - 12 0 - 10 0 - 8 0 - 6 0 - 4 0 - 2 0 - 0 O O O -a-a 6 0 ~ Ti 1 r

8 0 10 0

Inle t (xl/10 ) TIM E (min ) — I 12 0
Outle t Figur e 3-25e . Inle t an dOutle t Concentratio nVersu s Cycl e Tim e fo r Adsorbe r # 3 99. 8

Instontoneou a TIM E (min ) Cummulotiv e Figur e 3-25f . Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Time fo r Adsorbe r # 3

3-6 3P.7 7

E a a y.* z o

U l u z o u

> • o z u . u 

### fc U l 26 0

24 0 - 22 0 - 20 0 18 0 16 0 - 140 - 12 0 - 10 0 - 8 0 - 6 0 - 4 0 - 2 0 - ^B-B-ar ^ BOtf^SoO B \a4Hi****** TM

20 0

Figur e 3-25g . Inle t an d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 4 99. 9

99. 8 -
99. 7 -
99. 6

99. 5 -
99. 4 -
99. 3 -
99. 2 -
99. 1 -
9 9 1 1 I I ' I " 14 0 16 0 IS O 20 0

Instantaneou s Cummutative Figur e 3-25h . Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Time o r Adsorbe r # 4

3-6 4P.7 8

30 0 28 0 H 26 0 24 0 - 22 0 - 20 0 - 18 0 - 16 0 14 0 - 12 0 - 10 0 - 8 0 - 6 0 - 4 0 2 0 H 0 

# V . e-e -

- B ^

• ••» » o a

a Inle t (xl/10 ) TIM E (min ) - 1 1 1 1 1 1 — 12 0 14 0 16 0 IS O
Outle t Figur e 3-25i . Inle t an d Outle t Concentratio nVersu s Cycl e Time fo r Adsorbe r # 5

c a u k o a o 

### S o 

### E U l

18 0

Inatantonaou s TIM E (min ) Cummutative Figur e 3-25J . Instantaneou s an d Cumulativ e Efficienc y Versu s Cycl e Time fo r Adsorbe r # 5 3-6 5P.7 9

30 0

E & a ^a Z o 

# s . z U l o z o o 28 0 26 0 H 24 0 22 0 20 0 - 18 0 - 16 0 - 14 0 - 12 0 - 10 0 - 8 0 - 6 0 - 4 0 2 0 H 0 jr^^-^B-B

- oooo o OOOOO O 

## ^Sr'N ,

•—•» - 2 0 4 0 6 0

Inle t (xl/10 ) TIM E (min ) Oude t Figur e 3-25k . Inle

t an d Outlet Concentratio n Versu s Cycl e Tim

e fo r Adsorbe

r #6 .

c a o a

>
- u z U l u U l 10 0 - 99. 9 - 99. 8 - 99. 7 - 99. 6 - 99. 5 - 99. 4 - 99. 3 - 99. 2 - 99. 1 - 9 9 - 98. 9 - 98. 8 - 98. 7 - 98. 6 - 98. 5 - •I -

2 0 • —I' " I

4 0
Instantaneou s I •

6 0 8 0 .. . r _ 10 0 TIM E (min ) — •. 1 12 0
Cummutativ e . I

14 0 T "

16 0

Figur e 3-251 . Instantaneou s an d Cumulativ

e Efficienc

y Versu s Cycl e Tim

e fo r Adsorbe

r #6 . 3-6 6P.8 0

adsorption . I

never y cas e wher e th e remova l efficienc y wa s les s tha n 9 5 percent , correctabl e an d easil y identifiabl e operationa l problem s wer e responsibl e fo r lowe r remova l efficiencies . Th e key t o achievin g 9 5 percen t remova l i s prope r desig nan d operatio n o f th e adsorptio nsystem . I f thi s i s done , maintainin g a remova l efficienc y o f 9 5 percen t become s onl y a matte r o f cos t wher e th e economi c trade-off s com e i nth e form

o f stea

m cos t versu s carbo nreplacemen t costs . Th e carbo n mus t b e steame d sufficientl y t o desor bth e adsorbate , bu t excessiv e stea m us e raise s th e operatin g costs . Th e adsorptio ntime mus t b e sufficientl y lon g t o allow

regeneratio no f th e othe r bed(s) . Thi s wil l requir e replacemen t o f th e carbo nwhe nit s workin g capacit y get s to o low . I nSectio n3. 4 i t wa s show ntha t i f a system

i s designe d fo r a ful l rang e o f operatin g conditions , operate d correctly , an d th e carbo ni s replace d befor e it s workin g capacit y ha s bee nreduce d t o th e poin t wher e bed s ar e operate d afte r breakthrough , th e short-term remova l efficienc y

shoul d no t
var y significantly . Base d onth e informatio nan d dat a presente d here , i t ca nb e conclude d tha t a remova l efficienc y o f 9 5 percen t o r greate r i s continuousl y

achievable .

3-6 7P.8 1

4 . CARBO N

ADSORPTIO N

SYSTE M A T COMMENTER' S FACILIT Y

Thi s sectio npresent s a nanalysi s o f th e carbo nadsorptio nsystem locate d
a t th e commenter' s facility . Th e informatio npresente dcontain s dat a fo r whic hth e commente r ha s mad e a clai m o f confidentiality . Thi s informatio ni s locate di nth e confidentia l file s o f th e Director , Emissio nStandard s Division , Offic e o f Ai r Qualit y Plannin g an

dStandards , U . S . Environmenta l Protectio nAgency , Researc hTriangl e Park , Nort hCarolina . Thi s informatio n i s confidential , pendin g fina l determinatio nb y th e Administrator , an di s no t availabl e fo r publi c inspection .



### 4- 1P.8 2

2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 . 11 .

12 . 13 . 14 . 15 .
16 . 17 . 18 . 19 . 20 . 21 . 22 . 5 . REFERENCE S
U . S . Environmenta l Protectio nAgency , APT I Cours e 415 : Contro l o f Gaseou s Emissions . EPA-450/2-81-005 . Researc hTriangl e Park , Nort hCarolina . Decembe r 1981 . p . 5-4 . Referenc e 1 . Referenc e 1 , p . 5-6 . Referenc e 1 , p . 5-13 . Referenc e 1 , p . 5-2 . Referenc e 1 , p . 5-14 . Referenc e 1 , p . 5-14 . Referenc e 1 , p . 5-14 . Referenc e 1 , p . 5-3 . Referenc e 1 , p . 5-14 . Memorandu

m fro m Barnett , K . W. , Radia nCorporatio nt o Carbo nAdsorber / Condensatio nProjec t File . Februar y 29 , 1988 . Meetin g Minute s EPA/Calgo nCarbo nCorporation , p . 8 . Referenc e 11 , p . 7 . Referenc e 11 , p . 14 . Referenc e 11 , p . 18 . Crane , G. , Carbo nAdsorptio nfo r VO C Control . U . S . Environmenta l Protectio nAgency . Januar y 1982 . p . 18 . Referenc e 11 , pp . 17-18 . Referenc e 1 , p . 5-14 . Referenc e 1 , p . 5-20 . Referenc e 11 , p . 14 . Referenc e 11 , p . 14 . Referenc e 11 , p . 12 . Referenc e 11 , p . A-8 .



### 5- 123 . Referenc e 11 , p . 18 .

24 . Magneti c tap e Manufacturin g Industry - Backgroun d Informatio nfo r Propose d Standards . U . S . Enviormenta l Protectio nAgency . Researc h Triangl e Park , Nort hCaronlina . Publicatio nNo . EPA-450/3-85-029a . Decembe r 1985 . Appendi xC . 25 . Memorandu

m fro m Crumpler , D. , U . S . Environmenta l Protectio nAgenc y t o Berry , J. , U . S . Environmenta l Protectio nAgency . Apri l 21 , 1988 . Plan t Visi t t o Ampe xCorporation , p . 2 . 26 . Referenc e 11 , p . 14 . 27 . Miller , K . J. , C . R . Noddings , an d R . C . Nattkemper . 3 M Company . St . Paul , Minnesota . (Presente d a t Ai r Pollutio nContro l Associatio n Meeting . Ne w

York , New

York . Jun e 21-26 , 1987. ) p . 4 . 28 . Memorandu

m fro m May , P. , Radia nCorporation , t o file . Ma y 23 , 1988 . Ampe xDat a Analysis , p . 14 . 29 . Referenc e 28 , p . 14 . 30 . Referenc e 11 , pp . 14 , 17 . 31 . U . S . Environmenta l Protectio nAgency , Industria l Surfac e Coatin g Emissio nTes t Report : Genera l Tir e an d Rubbe r Company ; Reading , Massachusetts ; Tes t Serie s 2 . EPA/EMB-80-VNC-1B . Researc hTriangl e Park , Nort hCarolina . Jul y 1982 . Appendi xB.l . 32 . Referenc e 31 . 33 . Referenc e 11 , p . 10 . 34 . Lette r fro

m Shuliger , W. , Calgo nCarbo nCorporatio nt o Wyatt , S . R. , EPA . Novembe r 11 , 1987 . Respons e t o informatio nrequest . 35 . Referenc e 28 , p . 5 . 36 . Referenc e 11 , p . 19 . 37 . Referenc e 28 , p . 14 . 38 . Referenc e 28 , p . 13 . 39 . Lette r an

d attachment s fro

m Sapovich , M. , Diversitec hGeneral , t o Farmer , J. , U . S . Environmenta l Protectio nAgency . Januar y 12 , 1988 . Respons e t o Sectio n11 4 informatio nrequest .



### 5- 2P.8 4



### 40 .

41 .

42 . 43 . 44 . 45 . 46 .

47 .

48 .

49 . 50 .

51 . 52 . 53 . 54 .

55 . Lette r an

d attachment s fro

m Jackson , P. , Dayc o Products , Inc. , t o Farmer , J . U . S . Environmenta l Protectio nAgency . Decembe r 12 , 1987 . Respons e t o Sectio n11 4 informatio nrequest . Lette r an

d attachment s fro

m Johnson , W. , R . J . Reynold s Tobacc o (Archer) , t o Farmer , J. , U . S . Environmenta l Protectio nAgency . Decembe r 21 , 1987 . Respons e t o Sectio n11 4 informatio nrequest . Referenc e 11 , p . 4 . Referenc e 11 , p . 4 . Referenc e 11 , p . 8 . Referenc e 11 , p . 10 . Blacksmith , J . R. , T . P . Nelson , an d J . L . Randal l (Radia n Corporation) . Ful l Scal e Carbo nAdsorptio nApplication s Study . Prepare d fo r U . S . Environmenta l Protectio nAgency . Cincinnati , Ohio . Contrac t No . 68-03-3038 . Ma y 1984 . 21 1 p . Feairheller , W . R . (Monsant o Researc hCorporation) . Graphi c Art s Emission s Tes t Report : Meredit hBurda , Lynchburg , Virginia . Prepare d fo r U . S . Environmenta l Protectio nAgency . Researc hTriangl e Park , Nort hCarolina . Publicatio nNo . 79-GRA-l . Marc h1979 . 3 0 p . Feairheller , W..R . (Monsant o Researc hCorporation) . Graphi c Art s Emissio nTes t Report : Texa s Colo r Printers , Dallas , Texas . Prepare d fo r U . S . Environmenta l Protectio nAgency . Researc hTriangl e Park , Nort hCarolina . Publicatio nNo . 79-GRA-3 . August , 1979 . Referenc e 31 . Lette r an

d attachment s fro

m Gilbert , R. , Ampe xt o Farmer , J . R. , U . S . Environmenta l Protectio nAgency . Decembe r 16 , 1987 . Respons e t o Sectio n11 4 questionnaire . Referenc e 39 . Referenc e 40 . Referenc e 46 . Ful l Scal e Carbo nAdsorptio nApplication s Study . Plan t 3 . Radia n Corporatio n(Prepare d fo r th e U . S . Environmenta l Protectio nAgency) . Cincinnati , Ohio . Augus t 19 , 1982 . Draf t Report . Ful l Scal e Carbo nAdsorptio nApplicatio nStudy . Plan t 4 . Radia n Corporatio n(Prepare d fo r th e U . S . Environmenta l Protectio nAgency) . Cincinnati , Ohio . Februar y 25 , 1983 .



### 5- 3P.8 5



### 56 . Ful l Scal e Carbo nAdsortpio nApplicatio nStudy . Plan t 6 . Radia n Corporatio n(Prepare dfo r th e U . S . Environmenta l Protectio nAgency) . Cincinnati , Ohio . Octobe r 29 , 1982 . 57 . Referenc e 46 , p . 108 . 58 . Referenc e 46 , p . 109 . 59 . Referenc e 46 , p . 110 . 60 . Referenc e 24 , pp . 3-4 .

5- 4