低负荷下蓄热式加热炉燃烧策略数值模拟

Numerical simulation of combustion strategy in a regenerative reheating furnace under low thermal load

针对低负荷下蓄热式加热炉燃烧性能下降的问题,以某钢厂蓄热式加热炉为研究对象,利用软件Fluent建立炉内气体流动、传热及燃烧过程数学模型。炉内气体的流动采用标准k-ε模型计算,燃烧过程的模拟采用混合分数/PDF模型,辐射换热采用DO模型计算。通过所建立的数学模型计算低负荷时,比例控制和脉冲控制2种情况下,炉内气体流动、气体体积分数及温度的分布。计算结果表明:在低负荷下,脉冲控制有利于加强煤气与空气的混合,提高煤气燃烧速率,防止O_2在钢坯表面的聚集,有利于减小钢坯的氧化烧损,提高钢坯表面热流沿炉宽方向分布的均匀性。

In order to solve the problem of combustion performance decrease caused by the decrease of thermal load in a regenerative reheating furnace, a mathematical model was developed to describe heat transfer, gas flow and combustion processes in a regenerative reheating furnace by Fluent. The standard k-ε turbulence model was used for modeling the gas flow. The mean mixture fraction/PDF model was used to describe combustion process in the furnace. The discrete ordinates model was used for modeling the radiative heat transfer. The characteristics of gas flow, distribution of volume fraction of gas species and temperature distribution for furnace under proportional control and pulse control under low thermal load were analyzed by the model. The results show that under low thermal load, the pulse control is beneficial to strengthen the mix of gas and air, increase the combustion rate, prevent the accumulation of O_2 on the surface of billet,decrease the oxidation burning loss of the billet, and improve the uniformity of distribution of heat flux to billet surface along the furnace width direction.