Potential of CO2 emission reduction of coal gasification combined with green electricity
For the processes to produce coal-based chemicals using coal gasification processes,combining with green electricity is an effec-tive method to achieve CO2 emission reduction because not only the CO2 emissions caused by combustion of coal to provide needed heat in gasifiers can be eliminated but also the higher hydrogen to carbon ratio(H/C)of synthesis gas can be obtained and the CO2 emissions in water-gas-shift unit can be reduced.The models of different conventional gasifiers were simulated and verified,and the correspond-ing green electric heating gasifiers were simulated.The trends on the composition of the gaseous products and the H/C of the syngas were simulated,and the influences on the products by temperature,sorts of coals,and sequence of reactor models were analyzed.Furthermore,the trends of H/C with temperature are investigated and the potential of CO2 emission reduction are calculated.It is found that the CO2 emissions of the reactors combining with green electricity decrease by 12.63％(fixed bed),11.01％(entrained flow bed),9.23％(transport bed)and 5.12％(fluidized bed),respectively.Besides,the H/C shows an upward trend.Temperature has a significant impact on the composition of syngas,and the reactors for decoupling pyrolysis and gasification reactions to some extent affect the composition of syngas.When the temperature is below 1 500 K,the H/C decreases with the increase of temperature.When the temperature is above 1 500 K,the hydrogen to carbon ratio slowly increases with the increase of temperature.Decoupling pyrolysis and operating under lower pressure can help to achieve a higher H/C and lower CO2 emission,and the gasifiers operating under more moderate conditions have more potential of CO2 emission reduction.The efficiency advantage of the fixed bed coupling with green electricity is obvious.Considering the technical difficulties of high-temperature reactors coupled with green electricity,fixed bed,fluidized bed,and transport bed reactors cou-pled with green electricity are more feasible.
coal gasificationprocess simulationCO2 emission reductionhydrogen to carbon ratiogreen electricity
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