Simulation of sorption-enhanced gasification: H[formula omitted]O staging to a circulating fluidised bed gasifier to tailor the producer gas composition

Abstract

Sorption-enhanced gasification (SEG) is an advanced gasification technology for biofuel and biochemical synthesis processes. The SEG process allows tailoring of the producer gas composition for different synthesis processes by adjusting the temperature of the gasifier. Conventionally, the solids circulation rate from the combustor to the gasifier has been used to tailor producer gas composition. In this study, H2O staging is investigated in a circulating fluidised bed (CFB) gasifier as an alternative approach. The H2O staging can be used to decrease the riser temperature locally to enhance the main chemical reactions. The H2O staging as gas and liquid phases were considered in this study. Also, reactor cooling was combined with the staging. A validated one-dimensional CFB gasifier model was used to investigate the process. The simulation results indicate that H2O staging and cooling enhance the gasifier’s limestone carbonation and water-gas shift reactions. Thus, allowing to tailor the producer gas composition directly by adjusting the gasifier’s operating parameters. The methods investigated increase flexibility for operating the SEG CFB gasifier and the reactor system. Understanding different operation methods of the process and their impact on the system’s operation enables more flexible use and design of the gasification process.