生物质热燃气多孔介质直燃机理与脱焦特性研究

Direct Combustion Mechanism of Biomass Hot Gas in Porous Media and Tar Removal Characteristics

为研究含焦油的生物质热燃气在多孔介质中的燃烧机理与焦油燃烧脱除特性,采用固相实体颗粒堆积法模拟多孔介质,通过分析燃烧过程中反应器内温度、热流密度以及反应动力学速率等参数场的分布特征,揭示了当量比对生物质热燃气多孔介质燃烧过程的显著影响作用。研究表明,焦油燃烧脱除过程中直接氧化反应速率高是决定焦油出口浓度小、转化率高的关键因素。在燃烧火焰锋面的前沿,固体温度高于气体温度,热量由固体传向气体,对输运中的含焦生物质热燃气起到了预热和保温作用,使得热燃气中焦油保持气态不至于凝结。综合考虑生物质热燃气的完全燃烧与焦油脱除效率的提升,当量比应在0.8附近区域内选择。研究结果证实了生物质热燃气多孔介质直燃技术的脱焦优势。

In order to study the combustion mechanism of biomass hot gas containing tar in porous media and characteristics of tar combustion and removal,solid particle packing method was adopt to simulate the porous media,the distribution characteristics of temperature,heat flux density and reaction kinetic rate in the reactor during combustion were analyzed,and the significant influence of equivalence ratio on the direct combustion mechanism of biomass hot gas in porous media was revealed.The results showed that the direct oxidation reaction rate was high in the tar combustion and removal process,which determined the low tar outlet concentration and high conversion rate.At the front of the combustion flame,temperature of the solid was higher than the gas,the heat was transferred from solid to gas,which played a preheating and heat preservation role for the biomass hot gas containing tar,so that the tar in the hot gas remained gaseous and did not condense.In consideration of the complete combustion of biomass hot gas and the improvement of tar removal efficiency,the equivalent ratio should be selected in the region around 0.8.The results confirmed the advantages of the direct combustion technology of biomass hot gas porous media.