Time Scale Analysis of a Fluidized-Bed Catalytic Reactor Based on a Generalized Dynamic Model

Transcription

1 Reeeed Poceedngs The h Inenaonal oneence on Fludzaon - ew Hozons n Fludzaon ngneeng ngneeng oneences Inenaonal Yea 007 Tme cale Analyss o a Fludzed-Bed aalyc Reaco Based on a Genealzed Dynamc Model Andes Mahecha-Boeo John R Gace ad H lnashae Jm Lm nvesy o Bsh olumba, andesm@chmlubcca nvesy o Bsh olumba, gace@chmlubcca Pennsylvana ae nvesy, nashae@chmlubcca The nvesy o Bsh olumba, clm@chmlubcca Ths pape s posed a I Dgal Achves hp://dcengconnlog/ludzaon x/76

2 FLIDIZATIO XII 63 Mahecha-Boeo e al: Tme cale Analyss o a Fludzed-Bed aalyc Reaco TIM-AL AALYI OF A FLIDIZD-BD ATALYTI RATOR BAD O A GRALIZD DYAMI MODL Andés Mahecha-Boeo, John R Gace, ad H lnashae, Jm Lm Depamen o hemcal and Bologcal ngneeng, nvesy o Bsh olumba, 360 as Mall, Vancouve, anada V6TZ3 T: ; F: ; : andesm@chmlubcca ABTRAT A ludzed-bed eaco model s mplemened o smulae a Malec Anhydde MA eaco wh specal emphass on s dynamc behavou The dynamc model s geneal enough ha can ea a wde ange o alyc sysems, subec o mass and enegy balances whn he phases The model epesens mulple phases and egons low-densy phase, hgh-densy phase, eeboad egon and can accoun o hea and mass axal and adal ansoopc dspeson, change n mola/volumec low due o eacon, empeaue and pessue poles, hydodynamc egme vaaon, alys deacvaon, enegy opons, and mulple membanes o vaous geomees o noducon/exacon o any compound The model educes, as specal cases, o mos ludzed bed eaco models epoed n he leaue, allowng he nluence o smplyng assumpons o be nvesgaed Inoducon o deen assumpons o a MA ludzed-bed eaco o ndusal scale eveal que deen pedced me scales o key dynamc phenomena nheen o he pocess A mass anse/eacon me scale was ound o be close o he esdence me o he gas molecules n he eaco The hea anse me scale s seveal odes o magnude lage o he cuen sysem Ths ype o me-scale analyss may be a useul ool o deny he appopae degee o sophson o pedc he dynamcs o complex eacng sysems ITRODTIO Fludzed-bed eacos, lke many ohe ndusal and naual pocesses, nvolve mulple phenomena ha occu a deen aes In a ludzed-bed eaco, phenomena such as mulphase low, mass anse/eacon and hea anse ake place n coupled non-lnea ways Dynamc modellng o such phenomena eques mahemacal elaons ha descbe he neacon beween he sysem sae vaables and paamees, accounng o he evoluon n me In hs pape, a compehensve dynamc model s pesened, and s deen me scales ae dened o gan nsgh no he dynamc behavou o ludzed-beds Pedcng he behavou o gas-sold ludzed-bed eacos eques nomaon on eacon knecs, sochomey, hemodynamcs, hea and mass anse and low paens o he deen phases n he eaco Many eaco models have been poposed n he leaue In addon o hose evewed by Yaes, Gace and Ho 3, moe ecen ones nclude Thompson e al 4, Abba e al 5 and hen e al 6 ach o hese ncopoaes a deen se o assumpons, leadng o a deen se o mahemacal expessons o smulae he eaco Ths pape uses a compehensve model ha bulds upon mos o he eaues om pevous modellng eos, ncludng dynamc behavou The dynamc behavou o complex sysems oen conans mulple me scales 7 Ae an nal ansen peod, may be possble o consde some as phenomena as hey wee nsananeous elave o slowe ones 7 Fo nsance, hydodynamc phenomena may each a Publshed pseudo-seady-sae by I Dgal Achves, much 007 moe quckly han hea anse n ludzed bed eacos The

3 MAHHA-BOTRO e al 64 denon o deen me scales may hen be used o smply he numecal soluon o he sysem model 8- FDAMTAL DIFFRTIAL DYAMI MODL FOR ATALYTI YTM A genealzed dynamc model s developed o gas-sold alyc ludzed-bed eacos Fo uhe deals egadng hs model see Mahecha-Boeo e al -4 Mole Balance The mola ae balance ove a deenal elemen o phase φ s gven by: [onvecve npu onvecve oupu] gas [Dusve npu Dusve oupu] gas [Reacon geneaon/consumpon] [xchange] φ [Accumulaon ae] gas The numbe o mole balance equaons s The ems n he geneal mole balance o componen n phase φ ae shown n symbols as ollows: [ ] { } [ ] [ ] { } [ ] [ ] gas R R σ σ Hee s he concenaon o speces, he veco o convecve velocy, he veco o dspesve mola luxes calculaed usng Fck s o ean-maxwell duson negy Balance The deenal enegy balance o phase φ s gven by: [onvecve hea npu onvecve hea oupu] gas [Dusve hea npu Dusve hea oupu] gas [hemcal eacon hea geneaon/consumpon] [Hea exchange wh ohe phases and suoundngs] φ [Hea accumulaon ae] gas gas H H q R R p The ems n he geneal balance ae shown n symbols above The numbe o enegy The h Inenaonal oneence on Fludzaon - ew Hozons n Fludzaon ngneeng, A 76 [007] hp://dcengconnlog/ludzaon_x/76

4 FLIDIZATIO XII 65 balance equaons Mahecha-Boeo s Hee e al: Tme cale s he Analyss nenal o a Fludzed-Bed enegy o aalyc componen Reaco, and q s he veco o conducve hea luxes calculaed usng Foue s law o conducon Ohe symbols n hese consevaon equaons ae dened n he oaon secon Pessue Balance A smpled deenal pessue balance n he z-decon o phase φ s gven by: dp { [ ] gas} g 3 dz Bounday and Inal ondons The bounday condons may assume axal symmey, zeo lux a he walls and Danckwes cea 5 wh duson assumed o be neglgble n he oe and ae secons A base se o bounday condons s dsplayed n Table A 0 T Table Bounday and nal condons z : K A T ] z gas ] p T 0 0, z ] ] gas 0 0 z A z L T : 0, 0 A 0 z z D z, z 0 P : 0 P T T, 0 A TDY: APPLIATIO TO A IDTRIAL MA FLIDIZD-BD RATOR Malec Anhydde MA s an mpoan nemedae n he poducon o umac and aac acds, unsauaed polyese esns, chemcals o agculue, alkd esns, lubcan ols, copolymes, ood addves and uawee 6, 7 Inally, MA was poduced om benzene 7, bu due o envonmenal and economc consans, s cuenly poduced commecally by paal oxdaon o n-buane ove a vanadum phosphoous oxdevpo alys 8, nvolvng complex heeogeneously-alyzed eacons 9 and he only alkane-selecve oxdaon eacon used n ndusy 0 The alyc eacons occu hough uenal educon-oxdaon o he alys suace and selecve geneaon o MA Fludzed bed eacos now play a mao ole n MA synhess, aclang excellen hea anse and avodng ho spos As well, hghe eacan concenaons can be ed whou geneang explosve mxues because he ludzed alys acs as a lame aese The dmensons and opeang condons gven n Table, ae smla o hose n some ndusal uns Reacon Knecs 3 The well-documened knecs o en e al 3 wee employed n ou smulaons These ae wdely used 7, 4 and can poduce accuae speces conveson pedcons 5 A angula eacon scheme commonly appeas n he leaue 7, 4, 5, based on he eale wok o en e al 3 The eacon aes ae hen descbed by: γ k4h 0 O 4H O ; 4 β O 3 O k x O ; 5 3 k 34H O 6 3 K δ B 4H0 4H0 whee Publshed s by he I ae Dgal o Achves, MA omaon, 007 he ae o buane oal oxdaon, and 3 he ae o MA 3

5 66 MAHHA-BOTRO e al oal oxdaon The h Inenaonal The coespondng oneence on Fludzaon knec consans - ew Hozons 3 n appea Fludzaon n Table ngneeng, 3 A 76 [007] Table Key eaco paamees Paamee Value Paamee Value Gas nle empeaue 63 [K] aalys densy 000 [kg/m 3 ] Pessue a dsbuo level 500 [kpa] Inne damee 08 [m] xpanded bed hegh 6 [m] Buane eed 40 [m 3 /h] upecal gas velocy 06 [m/s] Oxygen eed 00 [m 3 /h] Mean pacle damee 50 [µm] ogen eed 800 [m 3 /h] Reaco shell pehea empeaue 53 [K] Table 3 Knec paamees om en e al 3 Tempeaue [K] k [mol - L g - s - ] k [mol - β L β g - s - ] k 3 [mol γ - δ L - γ - δ g - s - ] x x x x x x x x x 0-8 Ohe paamees: K B 66 [L mol - ]; β 098 [-]; γ [-]; δ 5[-] Poposed ochomey The ollowng sochomey s assumed o hs modelng wok The O:O mola ao s assumed o be, smla o values epoed by Loences e al 6 R : R : R 3: 4H 0 3 5O 4H O3 4H O H 5 5O 4O H O 4 0 X 5 4H O3 O 4O X H O Implemenaon o he geneal model The geneal model descbed above s appled o a MA eaco The dynamc model s solved by OMOL Mulphyscs 3b n a one-dmensonal geomey as descbed by equaons o 4 Feaues such as gas sopon, gas chemsopon, selecve membane pemeaon, and na-pacle duson ae no needed n he cuen compue smulaons A hea exchange em beween he gas and eacon vessel s ncluded on he le hand sde o om: R T R T A hea balance o he eaco vessel made o seel s developed n a smla way: K T a T T a T T T 6 R R R ool cool ool R R P R R R R whee subscp R denoes he eaco shell The eaco shell Bo numbe s low enough o ensue ha he adal vaaon n empeaue can be saely negleced, allowng o he mplemenaon o a -D model The sa-up polcy o solvng he model eques ha all speces concenaons nsde he eaco ae equal o he npu values A 0, all concenaon poles ae la along he eaco hegh uddenly, a 0 he eacon and convecon sa, and he conveson nceases gadually as me pogesses The shell s assumed o be exenally peheaed o 53 K, as well as nsulaed o peven hea loss quaons o 4 wee used o smulae he eaco, assumng an aveage e weghed by he acons n he bed empeaue o he Hgh and Low densy pseudo-phases as he eaco hp://dcengconnlog/ludzaon_x/76 empeaue 4

6 FLIDIZATIO XII 67 Mahecha-Boeo e al: Tme cale Analyss o a Fludzed-Bed aalyc Reaco RLT AD DIIO umecal smulaon o he sysem dynamcs unveled wo vey deen me scales: Mass anse/eacon me scale ysem dynamcs based on he mole balances o he chemcal speces nsde he eaco ae vey quck The me sep o he numecal smulaons needs o be kep below 0000 s o assue numecal sably due he speed o he conveconduson pocesses The me-sep equed o solve he model was esmaed by al and eo The me scale n hs case s ~0 s On he ohe hand, hea anse o/om he eaco vessel s vey slow and has vey lle nluence on he sysem dynamcs o he above me scale onveson poles a deen mes o he eaco ae depced n Fgue Fo hese cuves, all hea anse pocesses can be assumed o be a pseudo-seady-sae The shape o he poles s smla o eale ndngs 5 0 s onveson [-] Hegh [m] 0 s Fgue onveson vs Hegh [m] o deen mes one pole evey 05 s Hea anse me scale Because o he hemal nea o he eaco and s conens, hea anse nvolves a me scale many odes o magnude lage han he mass anse/eacon me scale Ou smulaons adop values o he sae vaables and paamees om he econ 4 smulaons ae 0 s e when he mass anse/eacon pocesses have essenally eached seady sae The sysem s hen smulaed by wo coupled enegy balances one o he eaco conens, he ohe o he vessel, wh speces concenaon poles, aes o eacon poles and hea geneaon poles aken om econ 4 above I was veed ha hs pocedue gave oveall soluons vey smla o hose whee all o he dynamc equaons wee solved smulaneously The me sep s nceased o ~0 s, and numecal sably s conseved 50,000 s ae equed o each seady-sae Ths conms ha he shell empeaue pole evolves, yng o equlbae wh he eaco empeaue The hea anse s much slowe han he mass anse/eacon phenomena Fgues and 3 depc empeaue poles ploed evey 500 s Publshed by I Dgal Achves, 007 5

7 68 MAHHA-BOTRO e al The h Inenaonal oneence on Fludzaon - ew Hozons n Fludzaon ngneeng, A 76 [007] 50,000 s Reaco Tempeaue [K] Hegh [m] 0 s Fgue Reaco empeaue vs hegh o deen mes poles a: 0 s, s, s, 5 s, 0 s,,000 s and 50,000 s 50,000 s hell Tempeaue [K] Hegh [m] 0 s Fgue 3 Reaco shell empeaue vs hegh a deen mes one pole evey 3,000 s Fom Fgue s clea ha he eaco empeaue has ase dynamcs han he eaco shell snce eaches almos s nal value ae ~000 s In hs mode o opeaon s sae o assume ha he mass anse/eacon pocesses ae a pseudo-seady-sae The me scale o he hea anse phenomena depend on he sze o he equpmen and also on whehe he vessel s exenally nsulaed o eacoy-lned eglecng he hea eecs o he eaco shell n econ 4 does no aec he esuls sgncanly Howeve, hs assumpon s no appopae hp://dcengconnlog/ludzaon_x/76 when esmang he me o each hemal seady sae 6

8 FLIDIZATIO XII 69 OLIO Mahecha-Boeo e al: Tme cale Analyss o a Fludzed-Bed aalyc Reaco Ou geneal dynamc model descbes ludzed bed eacos wh ewe smplyng assumpons han ohe models n he leaue Deen me scales ae dened o an ndusal MA eaco, povdng nsgh no he dynamc behavou o he sysem The genealzed model may be smpled dependng on he desed degee o sophson o a gven peod The model pedcs vey deen me scales o key dynamc phenomena nheen o he pocess A mass anse/eacon me scale was ound o be close o he esdence me o he gas molecules n he eaco Fuhemoe a hea anse me scale seveal odes o magnude lage was unveled o he cuen sysem Hea anse calculaons may be caed ou assumng ha he mass anse/eacon phenomena have eached a pseudo-seady sae In addon, s sae o neglec hea anse dynamcs o he nal ew seconds equed o he mass anse/eacon phenomena o sablze Ths ype o me-scale analyss may be a useul ool o deny he appopae degee o sophson o pedc he dynamcs o complex eacng sysems ome assumpons ae vald o a deemned neval o me, wheeas he same assumpon may be nvald appled when consdeng deen me scales OTATIO A Aea, m oncenaon o speces n phase φ, mol/m 3 Inenal enegy o speces n phase φ, J/mol R Inenal enegy o speces chemsobed on alys suace n phase φ, J/mol umbe o speces n phase φ, dmensonless Veco o dspesve mola luxes o speces n phase φ, mol/m s umbe o eacons, dmensonless umbe o pseudo-phases Inenal enegy o he alys n phase φ, J/kg P Pessue n phase φ, Pa Inenal enegy o speces chemsobed on solds soben suace n phase φ, J/mol q Inenal enegy o he solds soben n phase φ, J/kg Veco o dspesve mola luxes n phase φ, W/m Genealzed ae o eacon n phase φ, mol/kgs aalys chemsopon uncon mol/m aalys suace aea pe un volume, old soben chemsopon uncon mol/m g Gavaonal acceleaon, m/s H m - Tme, s Veco o convecve veloces o he alys n phase φ, m/s Hea o eacon, J/mol x,y,z Recangula coodnaes, m Geek Lees Volume o sold soben pe un o oal solds soben alys, dmensonless Vodage o phase φ, dmensonless ecveness aco, dmensonless σ Densy, kg/m 3 ubscps gas Gas aalys Reacon ompound φ Phase φ Publshed old by I soben Dgal Achves, 007 R Reaco shell R ochomec coecen o speces n eacon, dmensonless Acvy coecen assoed wh alys deacvaon, dmensonless 7

9 630 MAHHA-BOTRO e al RFFR The h Inenaonal oneence on Fludzaon - ew Hozons n Fludzaon ngneeng, A 76 [007] Yaes, JG, Fundamenals o ludzed-bed chemcal pocesses 983, London: Buewoh-Henemann Gace, JR, Flud beds as chemcal eacos, n Gas ludzaon echnology, D Gelda, do 986, Wlley, hchese: ew Yok 3 Ho, T, Modelng, n Handbook o ludzaon and lud pacle sysems, W Yang, do 003, Macel Dekke Incopoaed: ew Yok 4 Thompson, ML, HT B, and JR Gace, A genealzed bubblng/ubulen ludzed bed eaco model hem ng c, : p Abba, IA, JR Gace, and HT B, Applon o he genec ludzed-bed eaco model o he ludzed-bed membane eaco pocess o seam mehane eomng wh oxygen npu Ind ng hem Res, 003 4: p hen, Z, Y Yan, and H lnashae, aalys deacvaon and engneeng conol o seameomng o hghe hydocabons n a novel membane eome hem ng c, : p Okno, M and ML Mavovounos, mplon o Mahemacal Models o hemcal Reacon ysems hemcal Revews, : p Mualldha, R and D Ramklshna, Analyss o Dople oalescence n Tubulen Lqud-Lqud Dspesons Ind ng hem Fundam, 986 5: p Thompson, DR and R Lae, Mulple me scale analyss o wo models o he peoxdase-oxdase eacon haos, 995 5: p Voa, and P Daouds, onlnea Model Reducon o hemcal Reacon ysems AIh Jounal, : p e, D and P Dawson, Rescalng o duson coecens n wo-me scale chemcal sysems Jounal o hemcal Physcs, 000 : p Mahecha-Boeo, A, JR Gace, H lnashae, and J Lm, ompehensve modellng o gas ludzed-bed eacos allowng o ansens, mulple low egmes and selecve emoval o speces Inenaonal Jounal o hemcal Reaco ngneeng, A 3 Mahecha-Boeo, A, JR Gace, H lnashae, and J Lm ompehensve modellng o gas ludzed-bed eacos allowng o ansens, mulple low egmes and selecve emoval o speces n R X coneence, Innovaons n hemcal Reaco ngneeng 005 Zaecas, Mexco 4 Mahecha-Boeo, A, JR Gace, H lnashae, and J Lm, FMLAB smulaons usng a compehensve model o gas ludzed-bed eacos, n OMOL Mulphyscs FMLAB oneence poceedngs 005: Boson, A 5 Danckwes, PV, onnuous low sysems: Dsbuon o esdence mes hem ng c, 953 : p -3 6 Dene, M, Peucc, Toncon, M ecchn, and F Ghel, elecve oxdaon o n-buane o malec anhydde n lud bed eacos: dealed knec nvesgaon andeaco modellng hem ng c, : p Pugsley, T, G Paence, F Beu, and J haouk, Modelng he aalyc Oxdaon o n-buane o Malec Anhydde n a culang Fludzed Bed Reaco Ind ng hem Res, 99 3: p Golbg, KG and J Wehe, elecve synhess o malec anhydde by spaal sepaaon o n-buane oxdaon and alys eoxdaon hem ng c, 997 5: p Alonso, M, MJ Loences, MP Pna, and G Paence, Buane paal oxdaon n an exenally ludzed bed-membane eaco aalyss Today, 00 67: p Huang, X, L, B hen, and PL lveson, Tansen Knecs o n-buane Oxdaon o Malec Anhydde ove a VPO aalys AIh Jounal, 00 48: p Wang, D and MA Baeau, Oxdaon knecs o paally educed vanadyl pyophosphae alys Appled aalyss A: Geneal, 00 3: p 05 4 onaco, RM, Dupon's FB echnology o malec anhydde hem ng c, : p en, G, G Fonasa, and F To, n-buane Oxdaon o Malec Anhydde on Vanadum- Phosphoous oxdes: Knec analyss wh a ubula Flow aked-pelled Reaco Ind ng hem Pod Res Dev, 985 4: p Roy,, MP Dudukovc, and PL Mlls, A wo-phase compamens model o he selecve oxdaon o n-buane n a cculang ludzed bed eaco aalyss Today, 000 6: p Mosou,, H u, and J haouk, A ompason o Two- and ngle-phase Models o Fludzed- Bed Reacos Ind ng hem Res, 00 40: p Loences, MJ, G Paence, FV Dez, and J oca, Buane Oxdaon o Malec Anhydde: Knec Modelng and Bypoducs Ind ng hem Res, 003 4: p hp://dcengconnlog/ludzaon_x/76 8