预燃室燃烧器煤气化细灰混烧特性和数值模拟研究

Study on Co-combustion Characteristics and Numerical Simulation of Coal Gasification Fine Ash in Precombustion Chamber Burner

煤气化细灰(CGFA)通常作为固体废物填埋处理,不仅对环境有害,而且会损失大量的能量。采用SEM、拉曼、热重分析仪(TGA)研究了CGFA理化结构和着火、燃尽行为。利用激光多普勒相位测速仪器(PDA)测量工具研究了预燃室燃烧器气固流动特性,CFD数值模拟数据与PDA测量气固流动数据吻合。在0.3 MW预燃室燃烧器煤粉锅炉上,对不同掺混比的CGFA混烧进行了数值研究。CGFA为多孔结构,表面粗糙且孔隙发达。CGFA的石墨化程度低于褐煤煤焦和生物质焦。TGA结果表明CGFA与无烟煤具有相似的燃烧反应性、动力学和着火行为,因此CGFA燃烧模型采用无烟煤燃烧模型。CFD模拟结果表明,CGFA在0.3MW预燃室燃烧器煤粉炉内共燃是可行的。结合NO_(x)排放、炉温和燃尽率,CGFA掺混比例在30%最为合适。

Coal gasification fine ash(CGFA)is usually treated as solid waste landfill,which is not only harmful to the environment,but also will lose a lot of energy.The physicochemical structure,ignition and burnout behavior of CGFA were studied by SEM,Raman and thermogravimetric analyzer(TGA).The gas-solid flow characteristics of precombustion chamber burner are studied by using a three-dimensional particle dynamic analyzer(PDA).The CFD numerical simulation data are consistent with the gas-solid flow data measured by PDA.A numerical study was carried out on the mixed combustion of CGFA with different mixing ratios in a 0.3 MW precombustion chamber burner pulverized coal boiler.CGFA is a porous structure with rough surface and developed pores.The graphitization degree of CGFA is lower than that of lignite coal coke and biomass coke.TGA results show that cgfa and anthracite have similar combustion reactivity,kinetics and ignition behavior,so CGFA combustion model adopts anthracite combustion model.The CFD simulation results show that the co-combustion of CGFA in 0.3 MW precombustion chamber burner pulverized coal furnace is feasible.Combined with NO_(x) emission,furnace temperature and burnout rate,the mixing ratio of CGFA is 30%.