煤与生物质液排渣混烧特性的数值模拟

Numerical Simulation on the Slagging Co-combustion of Coal and Biomas

提出将液排渣低尘燃烧和混烧技术相结合的思路,并在自行编制的包含颗粒沉积、附壁燃烧及渣层流动等子模型的燃烧计算程序中加入生物质的热解和燃烧动力学模型,采用数值模拟手段对煤和木粉的液排渣混烧特性进行理论分析.对150kg/h燃料量的圆筒形燃烧器内燃烧特性的计算结果表明,添加25%(ω)木粉可以提高燃烧初始段的温度,有利于充分利用燃烧器的前部空间,可以加大燃烧初始阶段的反应速度,改善煤粉的着火性能,提高煤粉的空间燃尽及附壁燃尽效果,总体燃尽率提高5%,从而有利于颗粒在有限的空间内进行充分燃烧及原有煤粉燃烧装置的小型化改造或设计.理论分析研究证明,将混烧和液排渣低尘燃烧技术相结合,充分发挥两者的优势,用于工业窑炉洁净燃烧技术的开发是可行的。

Based on the new idea of unification of co-combustion and slagging combustion technologies, the pyrolysis and burning kinetic models of biomass were implanted into the WBSF-PCC （Wall Burning and Slag Flow in Pulverized Coal Combustion） code, which includes several sub-models of particle deposition, wall burning and slag flow. The co-combustion characteristics in a cylindrical combustor with 150 kg/h total feeding rate of coal and wood powder under different mixing ratios were simulated numerically. The results showed that adding wood powder at 25% mass fraction can increase the temperature at the initial stage of combustion, which is helpful to utilize the front space of the combustor; adding wood powder at 25% mass fraction can increase the reaction rate at the initial combustion stage, the coal ignitability is improved, the burnout efficiency is enhanced by about 5% of spatial and deposition particles, which is helpful for coal particles to bum entirely and for combustion devices to minimize its dimensions or sizes. The theoretic analysis in this work has proved that unification of co-combustion and slagging combustion technologies and its industrial application are feasible.