Fluidizedbed Membrane Reactors For Hydrogen Production From Natural Gas

Recently, the use of fuel cells increases in power generation and transportationapplications. The demand for hydrogen will grow correspondingly. This hydrogen will need tobe ultra-pure, and will have to be distributed conveniently and economically to end-users. Thefluidized bed membrane reactor has attracted general attention for its many advantages. Dr.Donglai Xie proposed a novel fluidized bed membrane reactor for ultra-pure hydrogenproduction in 2006. In this article, a novel fluidized bed membrane reactor, process flowdiagram (PFD) was designed and researched based on the model of FBMR.The main work of this paper contains:Modeling of fluidized bed membrane reactors for hydrogen production from steammethane reforming with Aspen Plus: The fluidized bed Membrane reactor was divided intoseveral successive steam methane sub-reformers and membrane sub-separators. The Gibbsminimum free energy sub-model in Aspen Plus was employed to simulate the steam methanereforming process in the sub-reformers. A FORTRAN sub-routine was integrated into AspenPlus to simulate hydrogen permeation through membranes in the sub-separator based onSieverts'law. Model predictions show satisfactory agreement with experimental data in theliterature. The influences of reactor pressure, temperature, steam-to-carbon ratio, andpermeate side hydrogen partial pressure on reactor performances were investigated with themodel. Extracting hydrogen in situ is shown to shift the equilibrium of steam methanereactions forward, removing the thermodynamic bottleneck, and improving hydrogen yieldwhile neutralizing, or even reversing, the adverse effect of pressure.Study of fluidized bed catalysts chemical properties. Catalytic activity is an importantdecision factor for reaction performance. A good catalyst could reach the chemical reactionclose to the thermodynamic equilibrium. To test the performance of the fluidized bed catalyst,a catalyst testing system was built in the laboratory. The results shown that the catalyst has agood catalytic activity, the reaction was closely to reach the chemical thermodynamicequilibrium.Anovel fluidized bed membrane reactor was designed.The reactorthatiscontainedinastainless steel vessel of height 2 mand inside diameter of 280 mm.The vessel can hold up to sixteendouble-sided membrane modules with a nominal permeation area of 130 cm2.The membrane modulescontained Pd/Ag foil of thickness 25 ?msealed onto a porous metal backing with a barrier layer toprevent inter diffusion.Air was introduced fromthe top of the reactor to air distributors at the bottomof the reactor.The membrane modules and air distributors were emplace by a radial ring type.To study the fluidized bed membrane reactor, a hydrogen production by natural gas was design.Thesystemwas including: feed supplying system, reacting systemand off-gas treatment system.