燃油锅炉容积热负荷与射流位置对内循环速率影响的数值模拟

Numerical Simulation on Internal Recirculation Rate Based on Volumetric Heat Capacity and Jet Location of Oil-fired Boiler

以Φ400 mm×1 920 mm大小的卧式燃油锅炉炉膛模型为研究对象,通过常温高速空气射流辅以烟气再循环的方式组织炉膛内空气动力场,对不同炉膛容积热负荷和多种空气射流位置进行了CFD模拟,并对炉膛内流场、温度场与组分场进行分析,研究炉膛容积热负荷与射流布置位置对内循环速率的影响。结果表明:当射流位置布置在炉膛内径0. 75处、炉膛热负荷为400 k W/m^3时,在炉膛内形成较大的回流区,内循环速率达到4以上,燃烧温度在1 400 K以下,温度场分布均匀,反应放热率明显降低,有利于形成燃油MILD燃烧。

A series of CFD simulations are conducted based on a horizontal oil-fired boiler furnace of 400 mm × 1 920 mm. The dynamic field of air and exhaust gas in the furnace is organized by means of exhaust gas recirculation combined with high speed air jet at atmospheric temperature. CFD simulations are carried out under different working conditions when the volumetric heat capacities and the position of air jet are changed. The dynamic field,temperature field and component field in the furnace are analyzed,and the relationship between the internal recirculation rate and volumetric heat capacity as well as the position of air jet in the furnace are discussed. The results show that when the jet located in 0. 75 of the furnace inner diameter and the volumetric heat capacity is 400 k W/m^3,a large recirculation zone is formed in the furnace. The internal circulation rate is above 4,the combustion temperature is below 1 400 K,the temperature field is flat and uniform,and the reaction heat release rate is obviously reduced,which is conducive to the formation of MILD combustion.