Modelling and simulation of autothermal reformer for synthesis gas production

One dimensional heterogeneous adiabatic fixed-bed reactor with supported nickel
catalyst is used to model the autothermal reformer for synthesis gas production. The flow
rate of natural gas along the catalyst bed is considered to vary in the axial direction. The
modeling and simulation of autothermal reformers is complex and requires detailed
understanding of natural gas reactions kinetics. To investigate these kinetics, different
kinetics models such as De Groote and Froment model are employed and predictions of
the kinetics parameters such as activation energies, rate constants, and adsorption
constants are made. An industrial plant for production of synthesis gas from natural gas,
for methanol production is taken as acase study. Amaterial and energy balance is carried
out for prediction of the input flow rates, feed composition to the autothermal reactor, and
the partial pressures to the reactants. The pressure drop is calculated using Ergun
equation. For the developed model, the rate of coke formation is neglected since suitable
CH4/02 ratio of 1.7 in the feed and natural gas stream temperature ofhigher than 850OC
are assumed. The effect of catalyst volume, gas superficial velocity, and combustion
temperature on temperature profile of autothermal reformer, conversion and rate of
reactions are studied. It is found that, the bed temperature can be reduced by 200 C, and
each 1.5 m3 reduced of catalyst volume increased the bed temperature by 160 C. While
increment of gas superficial velocity of 1m/s decreased the bed temperature by 150 C.