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

y

Particle

Tube ci*(x)

Cpi(y,x)Couplingvariables

0 2 4 6 8 10x (m)

0

0.04

0.08

0.12

Co

nver

sio

n

2.6

2.65

2.7

2.75

2.8

2.85

2.9

Velocity (m

/s)P co

ntrol

c

ontro

l

0 0.2 0.4 0.6 0.8 1x (m)

2

2.1

2.2

2.3

2.4

Vel

ocity

(m

/s)

0.022

0.023

0.024

0.025

0.026

Mea

n mo

lar m

ass (kg/m

ol)

Excerpt from the Proceedings of the 2014 COMSOL Conference in Boston