Calcium Looping Cycle for Hydrogen Production from Biomass Gasification Syngas: Experimental Investigation at a 20 kWth Dual Fluidized-Bed Facility

The use of a calcium looping cycle for the production of hydrogen (Ca-LHP) from biomass gasification syngas is a promising alternative to the conventionally used catalytic water-gas shift process. The process takes place in two fluidized bed reactors connected by solid CaO flow. In the first reactor (the carbonator), the water-gas shift reaction is enhanced by CO2 capture via the carbonation reaction with CaO. In the second reactor (the regenerator), the captured CO2 is released. This paper presents results from a continuously operated 20 kW(th) dual fluidized-bed facility using a syngas-like mixture obtained from biomass gasification. The influence of the main process parameters, i.e., temperature in the carbonator (T-carb), looping ratio (LR), and space time (t) on the H-2 concentration, and the CO conversion in the carbonator was investigated. A H-2 concentration of 84.4 vol?%(dry) and a CO conversion of 76.4% were achieved for a carbonator temperature of 639 degrees C, a looping ratio of 6 mol(Ca)/mol(CO+CO2), and a space time of 1.0 h. Additionally, experiments with different syngas compositions as obtained from various biomass fluidized bed gasification processes were performed and the mechanical stability as well as the chemical sorbent activity were studied. The potential of the calcium looping cycle for H-2 production could be shown by the experimental results obtained and their comparison with literature.