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利用CFD软件FLUENT对某石化企业废液焚烧余热锅炉内换热管壁上飞灰粒子碰撞及分布情况进行数值模拟研究。采用Eulerian-Largrangian法对余热锅炉内气-固两相流问题进行求解,重点分析粒子尺寸、烟气流速、纵向管间距、横向管间距等四种因素对飞灰粒子碰撞概率的影响情况。研究结果表明,除纵向管间距之外,其余三种因素对飞灰粒子的碰撞概率影响显著。飞灰粒子碰撞概率随粒子尺寸的增大而增大,其中大尺寸粒子主要在前两排换热管束的迎风侧发生碰撞,小尺寸粒子在迎风侧和背风侧均发生碰撞,且碰撞概率分布均匀。当烟气流速增大时,飞灰粒子碰撞概率随之增大,且20.0μm飞灰粒子比0.2μm飞灰粒子对烟气流速更为敏感。随着纵向管间距的增大,飞灰粒子碰撞概率仅出现轻微的下降趋势,而随着横向管间距的增大,飞灰粒子碰撞概率下降明显。
The CFD software FLUENT was used to simulate the collisions and distribution of fly ash particles on the heat transfer tube wall of waste heat incineration boiler in a petrochemical enterprise. Eulerian-Largrangian method was used to solve the problem of gas-solid two-phase flow in waste heat boiler. The impact of particle size, flue gas velocity, longitudinal tube spacing and transverse tube spacing on the collision probability of fly ash particles was analyzed. The results show that in addition to the longitudinal tube spacing, the other three factors have a significant impact on the collision probability of fly ash particles. The collision probability of fly ash particles increases with the increase of particle size, in which large particles mainly collide on the windward side of the first two rows of heat exchange tubes, small particles collide on both the leeward side and the windward side, and the collision probability distribution Evenly. When the flue gas velocity increases, the collision probability of fly ash particles increases, and 20.0μm fly ash particles are more sensitive to flue gas velocity than 0.2μm fly ash particles. With the increase of the longitudinal tube spacing, the collision probability of the fly ash particles shows only a slight downward trend, and with the increase of the transverse tube spacing, the collision probability of the fly ash particles drops significantly.