Steam gasification of biomass coupled with lime-based CO2 capture in a dual fluidized bed reactor: A modeling study

Steam gasification of biomass integrated with CO2 capture in a dual fluidized bed with carbon sequestration is among the promising technologies being developed for sustainable production of hydrogen. A simple steady state model which considers two coupled reactors, one calcining limestone particles, while the other steam gasifies biomass and simultaneously carbonates the lime sorbent, is developed in this paper. A stoichiometric equilibrium model is applied for biomass gasification, with enhancement of CO2 removal by carbonation and incomplete conversion of sorbent particles due to kinetic limitations, mixing of the solids and loss of sorbent reactivity because of sintering. To optimize the overall performance of the process, sensitivity analyses are preformed over the most important design and operational parameters. Model predictions are compared with available data from the literature, showing the influence of CO2 capture on gasification. A parametric study reveals the effects of key process variables such as temperature, pressure and solids circulation rate. The model is useful in identifying design and operating conditions for integrated gasification and carbon capture.