Simulation Of Chemical Looping Gasification And Power Generation System Based On Aspen Plus

Fossil fuels have brought about a series of environmental problems while promoting the rapid development of modern society.The transition to low-carbon energy has become the consensus of many countries.Our country has proposed the goals of"carbon peak"and"carbon neutrality"as well.Biomass has abundant reserves and very similar to fossil fuel in chemical structure.It is a carbon-neutral fuel that has the potential to replace fossil fuels.Biomass gasification power generation is one of the important means of biomass utilization.However,the high volatile content of biomass makes it produce a large amount of tar during the gasification process,which damages the equipment,so a new gasification technology is urgently needed.The chemical looping gasification technology has the advantages of small equipment investment,low gasification energy consumption,and less syngas tar content.Coupling it with the power generation system can improve the performance of power generation,reduce the cost of power generation and pollution.Therefore,the power generation system coupled with chemical looping gasification has great potential for development.In this paper,the Aspen Plus software was used to simulate the process,and the chemical looping gasification model was established and verified.The effects of different biomass grades and main operating parameters on chemical looping gasification were studied.In addition,the operating parameters were optimized.The results show that the higher the biomass grade,the greater the exergy loss during the gasification process.Among the main operating parameters of chemical looping gasification,the molar ratio of oxygen to biomass（λ）has the most important impact on the gasification process.The gasification temperature(T_GR)has little effect on the gasification process.The molar ratio of steam to biomass（n_S/n_B）mainly affects the ratio of H₂ and CO in the syngas.The results of the optimization of the sawdust operating parameters are:T_GR is 850°C,λis 0.25,and n_S/n_B is 0.8.Based on the research of chemical looping gasification,a biomass-based integrated gasification combined cycle coupled with chemical looping gasification was established to study the influence of gasification operating parameters on system performance,and compared the performance differences between the coupled system and the conventional system.The results show that the performance indexes of the system are improved with the increase of T_GR,while with the increase ofλand n_S/n_B,the power generation,energy efficiency and exergy efficiency of the system are reduced.However,whenλand n_S/n_B are too small,the system cannot meet the heat self-balance.Under the condition of a feed rate of 50.2 kg·s^–1 and the system meeting the self-balance of heat,the power generation of the coupled system is 376.14MW,and the exergy efficiency is 33.35%.While the power generation of the conventional system is 360.54 MW,and the exergy efficiency is 32.48%.Considering the dispersed distribution of biomass,high transportation costs,and large power generation systems requiring a lot of fuel,integrated power generation systems that complement biomass with other energy sources seems to be a more promising option.The multi-energy complementary power generation system with fossil energy,biomass and solar energy was established.The gasification conditions with different mixing ratios of corn stalk and lignite were optimized,and the effects of two different solar energy integration methods on the system performance were studied.The results show that the optimal gasification temperature of the fuel with corn stalk mass mixing ratio of 0.25%,50%and 75%is 850°C,and the optimal molar ratio of oxygen carrier to fuel decreases with the corn stalk mass mixing ratio increasing.Exergy efficiency of the system can be improved by integrating solar energy into the gas turbine cycle,but it is not obvious.Comparing the two systems with integrated solar energy,the coupling system that uses solar energy to heat compressed air has higher energy efficiency and exergy efficiency than the coupling system that uses solar energy to generate steam.