Computational fluid dynamic study of sorption enhanced steam reforming of methane/ethanol in circulating fluidized bed system

Abstract

Two-dimensional fluid dynamic models were used to optimize and design a proper pilot-scale system for sorption enhanced steam methane reforming (SESMR) and sorption enhanced steam reforming of ethanol (SESRE) in a circulating fluidized bed reactor (CFBR) using Ni-based catalyst and dolomite as sorbent. The CFBR system was separately designed as 3 parts: including a SESMR riser, a SESRE and a regenerator. The SESMR riser could get H2 purity reached equilibrium of 98.58% in dry basis with the highest H2 flux of 0.301 kg/m2s when operating with steam to carbon ratio of 4 mol/mol, gas velocity of 6 m/s, inlet temperature of 581°C. While the SESRE riser could get maximum H2 purity only 91.30% in dry basis with the highest H2 flux of 0.147 kg/m2s when operating with steam to ethanol ratio of 6 mol/mol, gas velocity of 3 m/s, inlet temperature of 600°C. Both the risers for SESMR and SESRE had the best design with diameter of 0.2 m, height of 7 m operating with solid flux of 200 kg/m2s and catalyst to sorbent ratio of 2.54 kg/kg. Lastly, in regenerator part, double-stage bubbling bed regenerators with 1.2 m width and 0.8 m height of bed could perfectly regenerate the sorbent when operating with gas velocity of 0.2 m/s and preheating the solids at 950°C. Overall, SESMR and SESRE had feasibility to continuously produce high purity with high production rate of H2 by this preferred design and conditions of CFBR system.