Study And Simulation On Methane Steam Reforming In Membrane Reactors

Methane steam reforming is by far the most dominating process technology for production of hydrogen. Recent years the increased requirement of hydrogen in industry, especial ly the study of a new clean energy DME, promoted hydrogen to a more and more important role as one of main raw materials for DME.In conservative process, the conversion of methane is limited by the thermodynamic equilibrium, so scientists started studying methane steam reforming in membrane reactors, caI led membrane reforming process. In membrane reforming, hydrogen is continuously removed from the reaction zone, which pushing the chemical equilibrium and enabling operation at moderate temperature, low pressure and in smal I reactors & short process. Then the total investment can be reduced.In this paper, how the parameters ( such as temperature, pressure, ratio of H20/CH4, membrane types, purge gas flow etc.) affect the conversions of GH4 in membrane reforming is presented, and also these effects had been compared with the results in non-membrane reforming. All results showed the conversions of CH4 in membrane reforming were much better than those in non-membrane reforming. In different membrane reactors, the conversions of CH4 also" had evident differences. The reason is the different membrane(also different purge gas flow etc.) allows different hydrogen permeation. The more permeated hydrogen amount creates stronger force of pushing chemical equilibrium to hydrogen production side.In different membrane reactors, CH4 conversions of experimental results are in order as follows:Pd/ALO23> Pd-Ag/SS ) Pt/Al2O3> Al2O3>Pd/SSThe modified simulations of experimental results by Proll software also have been conducted in this paper. This is the first time that ProlI software is applied on simulation of open reactors梞embrane reactors. The simulation results showed us the different hydrogen permeation in different membrane reactors:Pd/Al2O3(80%) > Pd-Ag/SS (30%) > Pt/Al2O3(28%)> Al2O3(25%)> Pd/SS (10%)A computing table is listed in this paper, which can calculate the reaction equi librium constants of a few reactions (including methane steam reforming reaction) from the change of standard reaction free energy. The computing table has modified the mistaken calculation of change of standard reaction free energy by a book.A kinetic model has been built in this paper:When hydrogen permeation is closed to 100%, this model shows an ideal membrane reactor.This paper also confirmed that the ideal mixed model, piston flow model and series model in Proll simulation could simulate the ideal situation of kinetic model perfectly.The combination of experiments and simulations conducted a new method to carry out research. Accurate simulations can predict some results which probably are very difficult got by experiments. So simulation by software wi 11 become a helpful method for research in the coming future.