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Modeling of Packed Bed Reactors: Hydrogen Production by the Steam Reforming of Methane and Glycerol A. G. Dixon, B. MacDonald and A. Olm, Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA Introduction: For gas-phase reactions with large mole changes in a packed tube reactor, density and velocity change. 1 We show how to include these in the reactor model, for methane steam reforming (MSR): CH 4 +H 2 O ↔ 3H 2 + CO CO + H 2 O ↔ CO 2 +H 2 CH 4 + 2H 2 O ↔ 4H 2 + CO 2 and steam reforming of glycerol (GSR): C 3 H 8 O 3 + 3H 2 O → 7H 2 + 3CO 2 We solve an isothermal model with a 1-D domain for the reactor tube coupled to a 2-D domain for the single particle 2 in COMSOL. Results: MSR has higher ∆P and lower reaction mole change. GSR has lower ∆P and high reaction mole change. Effects of both on velocity are accounted for by the model equations. Conclusions: Effects of mole increases on the gas velocity and conversion for MSR and GSR were simulated using the mean molar mass. Results are given for isothermal 1-D calculations; future work will extend to 2-D non-isothermal cases. References: 1. Allain, F.; Dixon, A. G., Modeling of transport and reaction in a catalytic bed using a catalyst particle model, COMSOL Conference, Boston (2010) 2. Petera, J.; Nowicki, L.; Ledakowicz, S., New numerical algorithm for solving multidimensional heterogeneous model of the fixed bed reactor, Chem. Eng. J. 214, 237-246 (2013) 3. Cropley, J. B.; Burgess, L. M.; Loke, R. A., The optimal design of a reactor for the hydrogenation of butyraldehyde to butanol, ACS Symp. Ser., 237, 255-270 (1984) Figure 1. Tube and particle geometry Figure 2. Methane pellet conc. Figure 3. MSR: Conv. and v Figure 4. Glycerol pellet conc. Figure 5. GSR: M and v 0 1 x y Particle Tube ci*(x) Cpi(y,x) Coupling variables 0 2 4 6 8 10 x (m) 0 0.04 0.08 0.12 Conversion 2.6 2.65 2.7 2.75 2.8 2.85 2.9 Velocity (m/s) P control cont ro l 0 0.2 0.4 0.6 0.8 1 x (m) 2 2.1 2.2 2.3 2.4 Velocity (m/s) 0.022 0.023 0.024 0.025 0.026 Mean molar mass (kg/mol) Excerpt from the Proceedings of the 2014 COMSOL Conference in Boston

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Page 1: Modeling of Packed Bed Reactors: Hydrogen Production by ... · Modeling of Packed Bed Reactors: Hydrogen Production by the ... heterogeneous model of the fixed bed reactor, ... optimal

Modeling of Packed Bed Reactors: Hydrogen Production by the Steam Reforming of Methane and Glycerol

A. G. Dixon, B. MacDonald and A. Olm, Department of Chemical Engineering,Worcester Polytechnic Institute, Worcester, MA, USA

Introduction: For gas-phase reactions withlarge mole changes in a packed tube reactor,density and velocity change.1 We show howto include these in the reactor model, formethane steam reforming (MSR):

CH4 + H2O ↔ 3H2 + COCO + H2O ↔ CO2 + H2

CH4 + 2H2O ↔ 4H2 + CO2and steam reforming of glycerol (GSR):

C3H8O3 + 3H2O → 7H2 + 3CO2We solve an isothermal model with a 1-Ddomain for the reactor tube coupled to a 2-Ddomain for the single particle2 in COMSOL.

Results: MSR has higher ∆P and lowerreaction mole change. GSR has lower ∆Pand high reaction mole change. Effects ofboth on velocity are accounted for by themodel equations.

Conclusions: Effects of mole increaseson the gas velocity and conversion forMSR and GSR were simulated using themean molar mass. Results are given forisothermal 1-D calculations; future workwill extend to 2-D non-isothermal cases.

References:1. Allain, F.; Dixon, A. G., Modeling of transport and

reaction in a catalytic bed using a catalyst particle model, COMSOL Conference, Boston (2010)

2. Petera, J.; Nowicki, L.; Ledakowicz, S., New numerical algorithm for solving multidimensional heterogeneous model of the fixed bed reactor, Chem. Eng. J. 214, 237-246 (2013)

3. Cropley, J. B.; Burgess, L. M.; Loke, R. A., The optimal design of a reactor for the hydrogenation of butyraldehyde to butanol, ACS Symp. Ser., 237, 255-270 (1984)Figure 1. Tube and particle geometry

Figure 2. Methane pellet conc. Figure 3. MSR: Conv. and v

Figure 4. Glycerol pellet conc. Figure 5. GSR: M and v

0 1x

Particle

Tube ci*(x)

Cpi(y,x)Couplingvariables

0 2 4 6 8 10x (m)

0.04

0.08

0.12

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