生物质化学链燃烧中燃烧特性与气固流动特性的CFD模拟研究OA

Computational fluid dynamics(CFD)simulations were conducted using a two-fluid model coupled with chemical reaction kinetics to investigate the gas-solid two-phase flow and combustion characteristics of pyrolysis gases from four typical biomass feedstocks(pine sawdust,corn straw,rice straw and almond shell)in the presence of three oxygen carriers(Fe2O3,CuO and CuFe2O4)in a chemical looping combustion(CLC)fuel reactor.The effects of reaction temperature on the combustion process were further explored.The results indicate that there are significant differences in the combustible gas components released by different biomass feedstocks during the pyrolysis stage.Pine sawdust produces relatively high CO and H2 contents(33.38％and 29.22％,respectively),which are slightly lower than the corresponding values for corn stalk and almond shell,but much higher than those of rice straw.After the combustion reaches a steady state,the residual combustible-gas content for pine sawdust(8％-12％)is much lower than that for corn stalk and almond shell,but slightly higher than that for rice straw.Considering both combustion stability and fuel conversion rate,pine sawdust exhibits the best combustion performance with an optimal reaction temperature of approximately 880 ℃.In addition,the effects of reaction temperature on the performance of different oxygen carriers differ markedly.The conversion rate of CuO decreases rapidly at high temperatures,while that of CuFe2O4 increases with rising temperature.The CO conversion rate of CuFe2O4 is significantly higher than that of Fe2O3 but slightly lower than that of CuO.Its H2 conversion rate is between that of Fe2O3 and CuO.Furthermore,CuFe2O4 maintains stable conversion rates for both CO and H 2 over the range of 760 ℃-920 ℃.Thus,the overall reaction performance of CuFe2O4 is superior to that of single-metal oxides(CuO and Fe2O3).