OXYCHLORINATION FLUID BED REACTOR MODELLING AND SIMULATION

Transcription

1 OXYCHLORINATION FLUI BE REACTOR MOELLING AN SIMULATION Jã Carlos Santos Morra (RLAM/OT w w w. c f d o l. c o m. r w w. c f d o l. c

2 PVC Trad Th PVC world dmand for th nxt 5 yars s stmatd n 10 mllon ton ut only 6,5 mllon tons wll addd n nw plant capacts. In Brazl 560 thousand ton untl Exprts forcast an yarly growth rat of 4,5% for th PVC world consumpton, manly caus n th mrgng countrs such as Chna, Inda and Brazl. Projctons for South Amrca and Brazl ndcat yarly growth of 5% and 7%, rspctvly. Th South Amrca PVC producton capacty s only 1,4 mllon tons a yar and th pr capta consumpton s of 4 kg for nhatant a yar n Brazl and 3 kg n Argntna. On th othr hand, n Europ and n th Untd Stats, 15 kg of PVC ar usd y nhatant a yar. In Chna, whr th markt PVC xpanson s on of th largst of th world, th consumpton s of 7 kg. w w w. c f d o l. c o m. r

3 Prolm charactrzaton Th goal was dvlop a modl for th smulaton a fludzd d oxychlornaton ractor n ordr to nvstgatd through th snstvty analyss th ffct of dffrnt paramtrs whch nflunc th ractor prformanc and thn apply optmzaton usng a commrcal softwar. w w w. c f d o l. c o m. r

4 Oxyractor Paramtrs ε mf u o /u mf H mf (m H (m Fr mf d p (µm d q (m 0, ,1 11,1 0, ,27 Fr mf s th Froud numr at mnmum fludzaton condtons. charactrzs th qualty of th fludzação (<0,13 ndcatv of partcl fludzaton u o /u mf s th rato twn th fdng spd and th flud surfac vlocty n th mnmum fludzaton condtons. Indcats th potntal of partcl drag or th d channlng w w w. c f d o l. c o m. r

5 Partcl Fludynamc Th two-phas fludzd d modl (ul mulson Flud Surfac vlocty n mnmal fludzaton condton: u mf d 2 p ( ρ s ρ 1650µ g g w w w. c f d o l. c o m. r

6 Partcl Fludynamc Bul damtr: d d 2 { (u u } 0, 4 q,m 0,374 o mf π { A (u u } 0, 4 q,o 0,374 o o mf d q d q,m (d q,m d q,o 0,3Z Rlatv vlocty: u 0, 1 / 2 r 711( gd Asolut Vlocty: u u u + o mf u r w w w. c f d o l. c o m. r

7 Partcl Fludynamc Vod fracton at mnmal fludzaton: ε mf 0,586 1 Ar 0,029 ρf ρp 0,021 Ar ρfd ρ f g µ 3 p ( ρp 2 Catalytc d Porosty: ε 1 (1 δ (1 ε mf Bd hght: L L f mf 1 ε 1 ε mf f ρ ρ mf f w w w. c f d o l. c o m. r

8 Hypothss Th two-phas fludzd d s a vald modl Th on-dmnson modl wth hat and mass axal scattrng s vald Th chmcal racton occurs only durng th mulson phas Th catalyst partcl lutraton outward th d s not ng consdrd Th chosn racton ntwork s rprsntd y fv chmcal ractons: oxychlornaton, dhydrochlornaton of th 1,2-dchlorothn, oxdaton of thn for CO and CO2, formaton of chlord ffusvty and th coffcnt of convcton rman constant n th axal drcton Th ractor s adaatc w w w. c f d o l. c o m. r

9 Mass Balanc Bul Phas: d dz A (k Q Q Q Q Q F F Q σ z σ (K u Emulson Phas: H NF N σ z N NF + (k A dz+ V(1 δ (1 ε Q 0 F Q. r Q + N N F σ z N NF ua (1 V(1 (1 Q + δ ε F QF Q. r w w w. c f d o l. c o m. r

10 Enrgy Balanc Bul Phas: u ρ C f pf dt dz (H (T T u z 0 T T ; T T ρ C f T pf T F dt (H (T T F z 0 F dz u ρ C f pf T.ln T T T F (H z T T (T T F βz (H β u ρ C f pf w w w. c f d o l. c o m. r

11 Enrgy Balanc Emulson Phas: Q,F ρ f,f C p,f,f (T F T rf Q,o ρ f,o C p,f,o (T T rf + H z 0 (H (T T A dz+ n + V(1 δ (1 ε ( Hrj r j + UAw (Tw T j1 0 UA 1 h A + 1 ln(o / 2πkL + 1 h A w w Nu 0,023 R 4 / 5 Pr 0,4 h Nu k h w 0,01844.C R K. d g p ρgc (1 ε Kg pg 0,43 d p ρ u g µ o 0,23 C C ps pg 0,8 ρp ρg 0,66 w w w. c f d o l. c o m. r

12 Mathmatc Modl- Molcular ffuson Th componnt mass flow s gvn y th Fck s Law for molcular dffuson: N c ffuson coffcnt for no polar gass (Equaton of Chapman-Enskog: 1 / 2 AB x10 3 To polar componnts: T Pσ 2 AB m 3 / 2 Ω x 1 M A + 1 M B Ω + 0, 196 T 2 * AB Ω * (Brokaw w w w. c f d o l. c o m. r

13 Mathmatc Modl- Molcular ffuson Coffcnt Stfan-Maxwll:,m N (1 y n j 1, j ( y y N j n j y j N N j Th ffctv dffusvt s otand y consdrng α 0 (dffuson controlld y chmcal racton ovr th surfac of th catalyst: Thn, f N α y N cf y n j 1 j y,j 1 1 y y j N N j w w w. c f d o l. c o m. r

14 Kntc Modl For th man racton a kntcs modl followng th Langmur-Hnshlwood thory was usd. For th rmanng 4 ractons, mprcal kntcs modls proposd y Gl'Prn t al. (1979a wr usd. CuCl2 C2H4+ 1/2O2+ 2HCl CH2CH2Cl2+ H o 2 T 240 C O Langmur-Hnshlwood krkacec r 1+ K C a E kr 269xp(-37,8/RT ; Ka 0,63 c w w w. c f d o l. c o m. r

15 Algorthm ESTIMATE VALUES T (I METHOS: Nwton-Raphson Fnt ffrncs Gauss CALCULATE THE MASS BALA CE FU CTIO FOR THE BUBBLE A EMULSIO PHASE ( O LI EAR ALGEBRAIC EQUATIO S SYSTEM (I (k+1 - (I (k < EMAX? SIM YES CALCULATE THE E ERGY BALA CE F FU CTIO A EMULSIO PHASE TEMPERATURE O O IS THE E ERGY FU CTIO BALA CE F 0? YES PRI T T, (I E w w w. c f d o l. c o m. r

16 Rsults Condtons for Modl Ractor prssur: 3,8 kgf/cm2g Tmpratur of th mulson phas: 240 C Fd tmpratur: 154 C Tmpratur of th coolng watr: 200 C Paramtrs Plant Modl Rlatv vaton % Rsdnc tm, s 35,35 35,27 - Ethn convrson, % 96,39 94,39 2,08% Ethn gan, % 97,61 95,99 1,65% w w w. c f d o l. c o m. r

17 Rsults Emulson Phas Tmpratur Th tmpratur rs rducs th slctvty of th racton. Such rducton n th slctvty as wll th tmpratur rs can osrvd y th hghr formaton of CO and CO 2. 1,00 1,00 0,98 Ethn Gan 0,96 0,94 0,92 0,90 0,95 0,90 0,85 Ethn Convrson n Ethn Gan Ethn Gan (Plant Ethn Convrson 0,88 0,86 0, Emulson phas tmpratur, C w w w. c f d o l. c o m. r

18 Rsults Bul amtr Whn th ul damtr ncrass mass transfr twn th ul phas and th mulson dcrass. Bsds, an ncras n th ul damtr favors a hghr transportaton of nonractd gas through th d, onc ragnts wll not mt th catalyst partcls. Ethn Convrton 0,96 0,95 0,94 0,93 0,92 0,91 0,90 0,35 0,45 0,55 0,65 0,75 0,85 dq (m XET w w w. c f d o l. c o m. r

19 Rsults Bd Hght Only aout 5% of th catalyst s usd for th racton. Lght varatons n d hght at mnmum fludzaton hav outstandng ffcts ovr th convrson up to 8 m. Byond ths valu, any trals to ncras th catalyst concntraton n th d to promot ncrass n th thn convrson, com conomcally not fasl. For th xpandd d, ths pont corrsponds to 9 m hght. Ethn Convrson 0,96 0,95 0,94 0,93 0,92 0, Hmf (m zmn w w w. c f d o l. c o m. r

20 Rsults Rsdnc Tm crasng n th gas surfac vlocty, th rsdnc tm ncrass and th avrag ul sz dcrass as th ntrfac mass and nrgy transfr ncrass. An ncras n rsdnc tm wll produc a rducton n slctvty what can xpland y th paralll ractons. 0,96 0,95 0,98 Ethn Convrson 0,94 0,93 0,92 0,91 0,90 0,89 0,94 0,90 Ethn Gan Ethn Convrson Ethn Gan 0,88 0, Rsdnc tm (s 0,86 w w w. c f d o l. c o m. r

21 Fnal Commnts Th psudo-homognous modl hypothss s vald and t was possl to conclud that th dffuson procss dos not pos as a lmtng phas for ths systm. Th optmzd valus for th rsdnc tm tnd to closd to 24 s for systms wth rcycl. Non-convrtd thn may rprocssd. Varatons n d hghts hav ffct on racton gans up to 9 m; aov ths valu, nvstmnts n catalyst quantty ncras com conomcally mpractcal as a way to ncras thn convrson. vlop a smulaton applyng mult-dmnson modl (CFX, Flunt, : Varyng th dstrutor dsgn to control uls damtrs y lmtng thr sz and thus, nlargng th fasl ara for mass and nrgy transfr twn phass. Bsds, th largr ragnts volum, confnd nsd th uls, favors th passag of gas through th d wthout ts contact wth th catalyst partcls. Som accssors such as affls can usd for rducton of uls damtr. Analyzr ffct of PS (mult-phas.. w w w. c f d o l. c o m. r