外循环式高固气比分解炉气相流场的数值模拟

摘要

外循环式分解炉是一种新型的反应器,主要用于新型干法水泥生产工艺.理论计算表明该炉型具有更稳定的热工性能和更高的出炉物料表观分解率.采用带旋流修正的k-ε双方程模型对外循环式分解炉内的气相湍流流场进行了数值模拟.分析了该分解炉内的气流流线特征和不同截面的压力分布和气流速度情况.结果表明:受三次风偏心进入的作用,气流在分解炉下部形成较为强烈的返混和旋流效应,进入分解炉上部后趋于稳定.流体进入旋流分离器后,形成稳定的下行旋转流动,接近出口时,受流动空间缩小的影响,流体加速流出分解炉.以上结果验证了该分解炉设计合理,为煤粉在炉内的燃烧、碳酸盐的分解提供了较好的流场.%External circulating precalciner is a new type of reactor, which is mainly applied to the new dry process for the cement manufacture. Theoretical calculation indicates that the external circulating precalciner possess more stability of thermal performance and higher apparent resolution rate of the discharge material. The numerical simulation of the gas flow field in the external circulating precalciner based on the RNG k-ε model is introduced. The characteristics of the gas flow stream line in the precalciner and the distribution of the pressure and gas velocity with different parts were analyzed.The results indicated that a relatively strong back mixing and rotational flow field formed in the under-part by the effect of the tertiary air partiality into precalciner, and the flow field becomes stable since the gas enters the top of the precalciner.When the fluid flows into the rotational flow separator, the steady downstream spin is formed. Affected by the reduction of flow space close to export, fluid flowing quicken outflow the precalciner. The simulation results verified the precalciner for the pulverized coal burning and the carbonate decomposing was designed reasonably.