Development of hybrid CSP biomass gasification process with supercritical carbon dioxide cycle for power generation

Abstract

Hybrid CSP biomass gasification process with supercritical carbon dioxide cycle for power generation was numerically investigated by aid of ASPEN Plus simulation model from which data was generated and further processed to measure system performance. The system comprised of solar aided biomass gasification integrated to sCO2 Bryton cycle that utilized the sCO2 –rich gases from a pressurized oxy-combustor to run a closed loop recompressed sCO2 Bryton cycle for mechanical power generation. Besides, a Rankine power cycle is run from steam generated from heat recovered from hot syngas. This system configuration is commonly known as Allam cycle. Specifically, the influences of sCO2 turbine inlet and outlet pressures, and the amount of sCO2 recycled back to the combustor in relation to performance of the system were examined. Further, comparisons to performances of the systems with indirect heating of the sCO2 and that without solar power input were done. The results show that net thermal efficiency of about 60% is attainable, which is better than most biomass based IGCC. Recycling sCO2 back to the combustor dilutes the syngas in the combustor and thus oxy-combustion at lower temperatures are possible. This points to a potential highly efficient Allam cycles operating at a practical temperature conditions for the current IGCC equipment technology. Further, higher inlet turbine pressure safeguards efficient operation of the Allam cycle for a wider range of exit pressures. Additionally, solar assisted Allam cycle affords higher net thermal efficiencies because of the extra power that is attained by avoiding combustion of syngas to provide heat for gasification. Further, it is shown that the performance of the system is superior to that of indirectly heated sCO2 and to that without solar aid. Further, the injected solar thermal energy boosts the power output as high as 52% and its conversion efficiency is around this value. And thus, solar aided Allam cycle looks promising.