Study on the effect of gasification agents on the integrated system of biomass gasification combined cycle and oxy-fuel combustion

摘要

An integrated system of biomass gasification combined cycle with oxy-fuel combustion was proposed. Considering the neutral character of biomass, the "negative emissions" were achieved. Different gasifying agents, including steam, CO_2, steam + O_2, CO_2 + O_2, steam + CO_2, and steam + CO_2 + O_2 were examined. The steam and CO_2 in gasifying agents were directly separated from flue gas in power generation unit. The effects of equivalence ratios and gasifying agent to biomass ratios on syngas production were studied. The results revealed that steam contributed to the yield of H_2, while it inhibited the generation of CO. CO_2 in the gasifying agent promoted the yield of CO. O_2 had little impact on H_2 production, but it significantly reduced the generation of CO and CH_4. The introduction of O_2 in gasifying agent reduced the syngas LHV while it generally raised the gasification efficiency. Furthermore, when O_2 was used to realize the autothermal gasification process, the net power generation efficiencies under steam + O_2 gasification, CO_2 + O_2 gasification and steam + CO_2 + O_2 gasification were 26.3%, 28.3% and 27.6%, respectively. These efficiencies were competitive considering the biomass disposal and carbon capture.