Modeling of trickle bed reactor for hydrotreating of vacuum gas oils: effect of kinetic type on reactor modeling

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Horatio Richards
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1 17 th Euopean ymposium on Compute Aided Pocess Engineeing ECAPE17 V. Plesu and P.. Agachi (Editos) 007 Elsevie B.V. All ights eseved. 1 Modeling of tickle bed eacto fo hydoteating of vacuum gas oils: effect of kinetic type on eacto modeling Favio Jiménez a, aina Ojeda a, Eduado ánchez a, Viatcheslav afaov a, Rubens Maciel Filho b a Industial Univesity of antande, Tel , Bucaamanga, Colombia, E- mail: kafaov@uis.edu.co b Univesidade Estadual de Campinas, UNICAMP Abstact The hydodesulfuization (D) pocesses eseach equies a lot of expeimental wok to define pomotion and inhibition effects and find out coelations between the vaiables that paticipate on the sulphu emoval. By means of modeling and simulation is possible to detemine the scope of the pocess, and by means of the sequential design of expeiments (DE) is possible to educe the expeimental wok equied though compaison of kinetic models, at the same time that it pedicts expeimental conditions that allow to select a unique model and estimate its paametes. The pupose of this wok was to simulate the D pocess using the mathematical model developed in pevious wok and seveal kinetic models founded in liteatue. Togethe simulation is poposed a DE-based softwae with Runge-utta outines, othogonal collocation methods an equential Quadatic Pogamming to develop the steps of the Design and to be used on pilot plant applications. The good agee between theoetical and expeimental data led to the development of a use-fiendly pogam to simulate the complex pocess, make easie the intepetation of simultaneous eactions, and become a useful tool fo to impove the opeation conditions of hydoteating industial eactos. eywods equential, expeiments, hydodesulfuization, kinetics, optimization

2 F. Jiménez et al. 1. Intoduction To accomplish with the actual legislation and at the same time impove the quality of liquid fuels, it is useful to simulate the petoleum faction hydoteating pocess at diffeent opeation conditions. oweve, it is necessay to cay out seies of expeimental tests, to study and chaacteize this pocess, in ode to detemine the best opeation conditions that allow establishing mathematic coelations between the studied vaiables. The kinetic is maybe the majo element of eacto modeling and simulation, and theefoe paticula attention must be paid. This wok is futhe development of ou eseach in the aea of compute aided modeling fo hydodesulfuization, hydodenitogenation and hydodeaomatization simultaneous eactions in a hydoteating industial pocess. In pevious wok [1] the pocess model was ceated by the combination of two multiphase models epoted in liteatue fo gas and liquid phase and fo solid phase espectively. The main pupose of this wok is to compae the behavio of DT eactions taking into account seveal kinetic models founded in liteatue, and apply techniques of DE in ode to select the kinetic model that best epesents the D pocess accoding with the opeative conditions suggested by the softwae itself. A complete eview of kinetic models fo diffeent petoleum factions was caied out, likewise compaative analysis fo type of pocessing, type and natue of eacting systems, modes of opeation, pocess conditions, expessions fo mass tansfe, physico-chemical popeties, and numeical methods to solve the espective equations systems was made, and used as a base fo cay out new expeimentation at pilot plant fo hydoteating of heavy petoleum factions.. Reacto Modeling Fo liquid and gas phases the thee-phase model epoted by osten and offman (1996) was combined with the solid phase model epoted by Foment et al. (1994). The main assumptions and model simplifications wee: eacto model is one-dimensional heteogeneous and opeates isothemally, the eactions occu in the liquid phase in contact with the catalyst suface, extenal mass tansfe is negligible, catalyst wetting is complete, thee is no catalyst deactivation; and thee is no evapoation of liquid The expessions fo estimation of the physico chemical popeties (in ode to solve the diffeential equations) wee obtained fom authos [-3]. Two diffeent data set of basic infomation fo the simulation, coesponding with eacto geomety (length and diamete), catalyst popeties (density, supeficial aea, equivalent size), inlet opeative conditions (tempeatue, pessue, liquid and gas flows), and inlet concentations of key components, among othes, wee selected in ode to compae all the kinetic models into the eacto model. The fist data set was obtained fom industial infomation [4] the second data set was obtained fom expeimental tests made at pilot plant [1]. Both data sets ae

3 Modeling of tickle bed eacto fo hydoteating of vacuum gas oils: effect of kinetic type on eacto modeling 3 pesented in Table 1. Finally, a use-fiendly computational pogam was developed based on pogamming of Matlab 7.0, which have many tools that allow to apply optimization pocess and diffeential equations solutions appoximation with a wide ange of defined maticial functions. The axial diection in eacto was pefomed using a fouth ode Runge-utta outine with vaiable step size, and the inta-paticle integation was caied out with an othogonal collocation method (second ode diffeential equations). 3. inetic Model To epesent the D pocess have been incopoated nine kinetic models (consideing the pesence of sulphu in fom of dibenzotiophene-) established by seveal authos [4-11]. ome of these models conside two kinetics expessions, one fo hydogenolysis and othe fo hydogenation of dibenzothiophene. The selected kinetic models to use in simulation of D pocess ae pesented in Table (donde i Reaction velocity of i component, C i Concentation, P i Pessue, k i Reaction velocity coefficients, i Absoption equilibium constant. 4. Results Concentations pofiles fo, and in liquid and gas phases coesponding with the consideed kinetic models wee obtained. In Figues 1-4 ae shown behavios fo concentation of in liquid phase along eacto (fo fou kinetic models, two Langmui-inshelwood type and two powe law type, like epesentatives of the othe kinetic models), wheeas in Figues 5-8 ae shown fo. These behavios ae based on data set of industial infomation. Table 1. Basic data sets fo eacto simulations Popety Value Popety Value Popety Value Popety Value Opeation Conditions Feed Chaacteistics Catalyst Chaacteistics Inlet Conditions 590* 968.1* 140* Pessue 3.1e6* Tempeatue Liquid Den. Real Dens. () ** (kg/m 3 ) 863** (kg/m 3 ) 337.8** 9e6** (Pa) Pessue (Pa) 5e6* 710* Pessue 0* Bula Dens. Reacto Chaacteistics 9e6** (kg/m 3 ) 37.3** 0** (Pa) 3.63*.8* Paticle 1.3e-3* 55.4* Gás Flow Diamete Conc. (m 3 19e- Diamete /s).e-5** (m) 1.6e-3** (mol/m 3 ) 66** 3** (m).09e-* 7.6* Especific 8.9e7* 56* Liquid Flow (m 3 Lenght (m) Aea Conc. /s) 1.1e-7** 0.73** (m /m 3 3.6e8** (mol/m 3 ) 0** ) *Data fom Foment et al. (1994) **Data fom Pilot Plant Conc. (mol/m 3 ) 0* 0** Table. inetic models fo simulation of D pocess.

4 4 F. Jiménez et al. Model ydogenolysis ydogenation 1. Gigis and Gates (1991) ( 1+ + ) ( 1+ ). Foment et CB k k al (1994) ( ) 3 3. Bodeick et 1+ k, τ k ' ' ' ( 1 + ' ), τ 1, σ, σ BP 3 al (1981) ( 1+ C + ) ( 1 ) + τ 1+, σ k +, σ +, σ C C kcc ( 1+ C )(1 + C ) 4. Avaam-Vasalos (003) 5. Chen et al (001) E D D D ( 1 ) A. C. C + + A 6. Van asselt et al (1999) 7. Tsamatsoulis and Papayannakos (1998)a A 1 + D D P.3 ( + P + P ) 1 8. Cotta and Maciel-Filho (000) 9. Tsamatsoulis and Papayannakos (1998)b k 1. P 1.5 D D P ( 1 + P ).3 Thee ae stong diffeences on the concentation pedicted values along the eacto when ae used Langmui inshelwood (L-) kinetic models with espect to powe law (P-L) kinetic models. The fomes pedict concentations with a gadual diminution along the eacto wheeas the othes ae in agee with a ponounced eduction of concentation on the fist section of the eacto. Is emakable point out that the employed paametes of this models depends on the specific expeimental wok conditions (diffeent fo most of the models), theefoe these diffeences could esult in tendencies and pedictions out of established oiginal ange. On the othe hand, the amount of sulphydic acid ( ) on the liquid aises vey fast on the fist secto of the eacto. Results using L- kinetic show almost constant poduction of along eacto, wheeas using P-L kinetic the is consumed vey fast and the diminish to almost zeo afte the fist secto of the eacto. The second data set of basic infomation (pilot plant) pesent highe tempeatue, almost twice the pessue, and some catalytic popeties ae bette fo DT pocess, elated with the fist data set. Theefoe the concentation pofiles (not shown hee) esult vey simila to the pesented in Fig.1-8, howeve the consume of and poduction of ae vey much faste and the slopes moe ponounced.

5 Modeling of tickle bed eacto fo hydoteating of vacuum gas oils: effect of kinetic type on eacto modeling 5 Figue 1. Bodeick et al.(1981) Figue. Foment et al.(1994) Figue 3. Van asselt et al.(1999) Figue 4. Chen et al.(001) Figues 1-4. Concentations pofiles fo (vetical axis) along eacto (hoizontal axis) Figue 5. Bodeick et al.(1981) Figue 6. Foment et al.(1994) Figue 7. Van asselt et al.(1999) Figue 8. Chen et al.(001) Figues 5-8. Concentations pofiles fo (vetical axis) along eacto (hoizontal axis)

6 6 F. Jiménez et al. On the othe hand, it was poposed the use of DE in ode to compae all the kinetic models and to select that which best epesent de D pocess ove the opeative conditions suggested by the softwae itself. Techniques like equential Quadatic Pogamming (QP) fo each one of the estained optimization pocess necessay fo the application of citeia of the DE, Othogonal Collocation Method fo the solution of the second ode diffeential equations, and Runge-utta method fo the systems of diffeential equations, wee used in the softwae. Fo the validation of discimination of kinetic models wee used esults epoted in liteatue [1], obtaining the same final kinetic model and estimating paametes in the same ode de magnitude with espect to those pesented by the authos. Tough a QP pocess, it was founded the expeimental point whee the nine selected kinetic models fo D pocess had the maximum diffeence in thei esponses. Then, each time some models had to be eliminated until completes the pocess. 5. Conclusions and futue wok Wee compaed seveal kinetic models into the modeling and simulation of a tickle bed eacto. It was developed specific softwae based on Matlab 7.0 fo simulation and sequential design of expeiments (DE) and wee validated with seveal papes epoted in liteatue, obtaining esults that ae in concodance with data and behavios epoted. Also, it was shown that powe law kinetic models geneate concentation pofiles fo consume of and poduction of vey diffeent with espect to Langmui-inshelwood kinetic models, howeve the softwae epoduced vey well the behavios fo eactive and poducts with two diffeent data set: industial and pilot plant infomation. Refeences 1. F. Jimenez, M. Nunez, V. afaov, 006, Comp. Aided Chem. Eng., 1A, M. Rodiguez, J. Ancheyta, 004, Enegy & Fuels, Vol.18, osten, U. offman, 1996, AIChE Jounal, Vol. 4, No G. Foment, G. Depauw, V. Vanysselbeghe, 1994, Ind. Eng. Chem. Res., Vol. 33, D. Avaam, I. Vasalos, I., 003, Cat. Today, Vol , J. Chen, Z. Ring and M. Dabos, 001, Ind. Eng. Chem. Res., Vol. 40, M. Gigis, B. Gates, 1991, Ind. Eng. Chem. Res., Vol. 30, B. Van asselt, P. Lebens,. Calis, C. Van D. Bleek, 1999, Chem. Eng. ci., Vol 54, D. Tsamatsoulis, N. Papayannakos, 1998, Chem. Eng. ci., Vol. 53, Nº19, R. Cotta, M. Wolf-Maciel, R. Maciel Filho, 000, Comp. & Chem. Eng., Vol. 4, D. Bodeick, B. Gates, 1981, AIChE Jounal,Vol I. Van Paijs, L. osten and G. Foment, 1986, Ind. Eng. Chem. Pod. Res, Vol 5, 437.

A scaling-up methodology for co-rotating twin-screw extruders

A scaling-up methodology for co-rotating twin-screw extruders A scaling-up methodology fo co-otating twin-scew extudes A. Gaspa-Cunha, J. A. Covas Institute fo Polymes and Composites/I3N, Univesity of Minho, Guimaães 4800-058, Potugal Abstact. Scaling-up of co-otating