Autothermal Process Simulation And Synergistic Reaction Characteristics Of Coal And Biomass Chemical Looping Gasification

CO₂ from coal and other fossil fuel consumption emissions are the main cause of global warming.The efficient and clean conversion of energy under the "carbon peak and carbon neutrality" vision depends on the innovation of process design and the development of green energy.Chemical looping gasification（CLG）is a new high-quality syngas production technology.The auto-thermal technology demonstration in MWth-scale CLG reactors is the key to its industrial application.Biomass is the renewable carbon source with the greatest potential to replace fossil fuels.The co-thermal conversion of coal and biomass under the chemical looping concept will become an attractive option for efficiency and improved quality utilization of energy.The paper focuses on the auto-thermal operation of the CLG system and the synergistic reaction characteristics of coal and biomass under CLG mode,using a combination of process simulation and experimental research,the technical reliability of auto-thermal CLG was tested,the process feasibility of coal and biomass co-pyrolysis in chemical looping mode was investigated,the process scale-up pathway of coal and biomass chemical looping synergistic gasification under a multi-scale reaction mode was designed.（1）The technical reliability of auto-thermal coal chemical looping gasification（CCLG）is tested based on the MWth scale CLG industrial demonstration plant.The CCLG system can realize auto-thermal operation at a solids circulation flow rate of 14499 kg/h.The optimal heat exchange network enables the system to completely avoid the consumption of heating utilities,and the thermodynamic irreversibility mainly comes from the redox process,the system thermal efficiency is 81.63%,and the total exergy efficiency is 41.10%.FR flue gas circulation caused high solids circulation and high exergy loss weakened the thermodynamic performance of the system.（2）Co-pyrolysis of coal and biomass in the chemical looping modes will be an innovative technical concept Reaction characteristics of corn straw（CS）and bituminous coal（BC）chemical looping co-pyrolysis（CLCP）are investigated by thermogravimetric coypled with mass spectrometry.The participation of oxygen carriers（OCs）weakens the devolatilization intensity of co-pyrolysis.The mixed fuel exhibits positive synergistic effects when the CS blending ratio is<50%.The Coats-Redfern integral method fits that the solid-solid interaction between OCs and coke changes the reaction kinetics,enhancing the co-pyrolysis reactivity of the high-temperature section.The most significant synergistic effect at the CS blending ratio is 30%and the CLCP activation energy is 26.35～40.57 kJ/mol.（3）The process scale-up route of multi-scale coal and biomass chemical looping co-gasification（CLCG）is established based on a thermogravimetric analyzer-batch bubbling fluidized bed-MWth scale industrial demonstration unit.The positive synergistic effect is the most significant at a bituminous coal blending ratio of 70%.Fuel synergy has a positive contribution to cold gas efficiency（CGE）and syngas yield（Ys）,and the optimal CGE and Ys of the fluidized bed are 68.92%and 4.305 Nm³/kg,respectively.The direct scale-up of the fluidization mode can be adapted to the pilot unit,and the system heat efficiency of auto-thermal CLCG is 66.84%.This work achieves the process upgrade of the CLCG from basic research to technology development to engineering demonstration.