Modeling and simulation of industrial adiabatic fixed-bed. reactor for the catalytic reforming of methane to syngas

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1 Modeln and sulaton o ndustal adabatc xed-bed Euopean oness o hecal Enneen (EE-6 openhaen, 16- eptebe 7 Modeln and sulaton o ndustal adabatc xed-bed eacto o the catalytc eon o ethane to synas M.Tahzadeh Mazandaan, H. Ebah hecal Enneen Depatent, Faculty o Enneen, Mazandaan Unvesty,.O.Box:484, Babol, Ian, E-al: tahzadeh@yahoo.co, Tel: , Fax: Abstact An ndustal adabatc xed-bed eacto o the catalytc eon o ethane to synthess as on a coecal suppoted N catalyst at hh tepeatue and pessue ( tot =9 ba, T =894 K, s sulated usn a steady-state one-densonal heteoeneous eacto odel. Both extenal concentaton and tepeatue adents as well as nta-patcle concentaton adents ae taken nto account. The ntnsc knetcs o the eon and wate-as sht eactons wee taken o Nuauch and Kkuch (1988.The as-phase and sold-phase contnuty and eney deental equatons ae solved sultaneously usn MATLAB sotwae. In ths poa the nte volue ethod s used o solvn the coespondn contnuty equatons n sold phase (catalyst. The data taken o the Khoasan petochecal copany s appled to the poposed odel to peo the sulaton and the sulated esults ae then copaed to the expeental data at the outlet o eacto. Keywods: ulaton, stea eon, nte volue, adabatc xed-bed eacto 1. Intoducton Upadn o natual as (ch n ethane nto oe valuable checals, such as synthess as (synas, has been nvestated ntensvely n the past decade. In ecent yeas, hydoen s consdeed a clean eney souce and ts aket deand s steadly nceasn [1, ]. tea eon o natual as s wdely used to poduce synas, a xtue o hydoen and cabon onoxde n vaous popotons []. ynas s used as eedstock n a nube o ndustal pocesses such as poducton o aona, ethanol synthess, the Fsche-Topsch pocess, and the hydooylaton o olens [4, 5]. The whole pocess s endothec and occus ove a N-based catalyst n tubula eactos; equlbu condtons ae quckly eached at hh tepeatue. Althouh the ntensve eseach eots have been peoed on the knetcs and echans o the eacton, the pepaaton o catalyst and the evaluaton o pocess

2 M.Tahzadeh Mazandaan et al. and equpent [6, 7], the detaled eacto odeln and sulaton o RM on an ndustal scale s equed. In ths wok an ndustal adabatc xed-bed eacto o the catalytc eon o ethane to synthess as s sulated usn a steady-state one-densonal heteoeneous eacto odel.. The odel Adabatc xed-bed RM eacto s sulated usn a steady-state one-densonal heteoeneous eacto odel. Inta-patcle concentaton adents wee taken nto account explctly, by solvn the contnuty equatons n the catalyst pellet at each poston alon the xed-bed eacto co-odnate. The eacto desns ae based on suppoted N catalysts, whch catalyse the oaton o synthess as va stea eon ollowed by wate-as sht eactons. The catalyst patcle s assued to be sotheal: the an tanspot esstance nsde the catalyst pellet s due to ass tanse, even n the case o hhly exothec eactons [8]. The as-phase and soldphase contnuty and eney equatons ae pesented n Table 1 toethe wth the coespondn ntal and bounday condtons as well as Lanu-Hnshelwood ate equatons o eon, and wate-as sht eactons. Table 1: Reacto odel and eacton ate equatons wth coespondn bounday condtons Gas phase dy k a v + (y y, = dz Q old phase Gas-phase bounday condtons dt h a V + dz Q c (T T = (1 εb T T = R W, ( H, h a v De, / t d d y, (X ( + R W, = X dx dx p Z = =,T = T (1 ( ( (4 (5 old-phase bounday condtons H 4 + H d,s X = ( = dx De, d,s s X = 1 ( X 1 = k(,s dx p Reacton Rate equaton [9] NK O O + H k (ph p H p O / 4 1 = kj / ol p H O (6 = (7 H 98 = NK O + H O O + H k (p p p / K H 98 = 41 kj / ol K eq,1 O H O eq, (8 = (9

3 Modeln and sulaton o ndustal adabatc xed-bed The odel equatons (1-(4 o a set o deental and alebac equatons. Inteaton alon the eacto co-odnate was caed out usn the MATLAB lbay outne. The sold-phase contnuty equatons wee solved at each nceent o the axal decton by eans o the ethod o nte volue. 4. ulaton esults The eacto and catalyst densons, as well as the opeatn condtons and eed coposton taken o the Khoasan petochecal copany used to peo the sulaton ae shown n Table. The calculated axal ole acton and the catalyst and as-phase tepeatue poles ae shown n Fues 1 and espectvely. Fue epesents easued and calculated values o as-phase ole actons at the outlet o eacto. Table : Reacto and catalyst densons, eed coposton, and opeatn condtons ulaton case Value Reacto d ( L ( ε (. B V ( Q (W atalyst nckel oxde (k. d c ( T (K D ( e, a V ( G (k V ( N 1 Feed coposton (ole acton H 4 H O H Opeatn condtons Q (k tot (ba T (K

4 M.Tahzadeh Mazandaan et al.. oncluson A steady-state, one-densonal heteoeneous eacto odel was used to desn adabatc xed-bed RM eactos o synthess as poducton. The eacto desns ae based on suppoted N catalysts, whch catalyse the oaton o synthess as va stea eon ollowed by wate-as sht eactons. Inta-patcle concentaton adents wee taken nto account explctly, by solvn the coespondn contnuty equatons at each poston alon the eacto co-odnate wth the nte volue ethod. The sulaton esults concenn the lobal behavo o RM eactos ae ven..8.7 Y YH4 YHO YO YO YH Z ( Fue 1: Reactant and poduct ole actons vs. axal eacto coodnate T (K 8 T Ts Z ( Fue : atalyst and as-phase tepeatues vs. axal eacto coodnate. 4

5 Modeln and sulaton o ndustal adabatc xed-bed.6 Y.4. H4 HO O O H Expeental data ulaton esults Fue : opason between sulated esults and expeental data at the outlet o eacto. Notaton extenal pellet suace aea pe unt eacto volue specc heat at constant pessue ola concentaton o speces nta-patcle ola concentaton o speces ola concentaton o speces, at the extenal pellet suace J.K.. K ol. ol. ol... eectve duson coecent o speces n catalyst D e, eacto daete d catalyst daete d c total ass o catalyst k G as-to-sold heat tanse coecent W.. K as-to-sold ass tanse coecent.. equlbu constant o eacton, eacton dependent - K eq, eacto lenth L patal pessue o coponent ba total pessue ba tot pellet adus net catalytc poducton ate o speces pe unt catalyst ass 4.K. cat.k cat sold tepeatue K T as-phase tepeatue K T ole acton o speces axal eacto co-odnate vod acton o packn ol. ol tot a V,, h k R w, catalyst densty K. heat ate W Q supecal ass low velocty K.. Q densonless pellet co-odnate - X y Z ε B 5

6 M.Tahzadeh Mazandaan et al. Reeences [1] F.A. outeles,. Douvatzdes,. Tsakaas, ( J. owe ouces, 1,. [] R. etes, R. Dahl, U. K. lutten,. al, D. tolten, ( J. owe ouces, 16, 8. [] Ao, J. N., (1999 Appled atalyss A, 176, 159. [4] Fusky, E., (1998 Appled atalyss A, 171, 177. [5] ena, M. A., Goez, J.., & Feo, J. L. G., (1996 Appled atalyss A, 144, 7. [6] Xu, J., & Foent, G. F., (1989 A.I.h.E. Jounal, 5, 88. [7] Bee, R. J., & Man, G. B., (1999 Industal and Enneen hesty Reseach, 8, 58. [8] Foent, G. F., & Bscho, K. B., (199 hecal eacto analyss and desn (pp and London: Wley. [9] Nuauch, T., & Kkuch, K., (1988 hecal Enneen cence, 4,