块煤在气化炉拱顶下落过程的数值模拟研究

Numerical Simulation Research on Dropping Behavior of Lump Coal from the Gasifier Dome

摘要: 针对块煤在气化炉下落过程的传热传质现象建立了块煤变化相关模型，利用程序进行数值求解。结果表明块煤在熔融气化炉拱顶自由空间内下落过程极为短暂，其过程为加速度逐渐变小，速度不断增加过程。块煤下落过程中温度变化显著，其变化主要集中在块煤外部节点，块煤内部各节点温度几乎保持不变。块煤外表面温度变化明显，下落初期升温速率较大，后期升温速率减小，温度缓慢升高。块煤内部节点受传热影响升温速度慢。块煤下落初期表面水分快速蒸发，内部节点水分蒸发速率低于表面。越靠近块煤中心节点水分蒸发速率越小；块煤内部挥发分脱除曲线近似呈“阶梯状”分布。下落过程中块煤密度减小。

Abstract: Several correlative models were developed to evaluate heat and mass transfer phenomenon and dropping behaviour of lump coal from the gasifier dome. Some programs were used to acquire si-mulation result. The result shows that the dropping time of lump coal from the gasifier dome is very short. The acceleration speed decreases while the speed is increasing during the process of dropping. Temperature changes of lump coal are obvious in the dropping process of lump coal. Temperature changes focus on external node of lump coal. The temperature of internal node of lump coal is almost constant. Temperature change of outside surface of lump coal is obvious and the heating rate is high at the beginning of dropping of lump coal. However the heating rate decreases later and the temperature of lump coal increases slowly. Increase of internal node temperature of lump coal is slow because of influence of heat transfer. The surface moisture evaporates rapidly at the beginning of dropping of lump coal. The moisture evaporation rate of internal node of lump coal is faster than that of external node. The nearer the note to the core of lump coal, the lower the evaporation rate. The volatile removal of internal node of lump coal shows the ladder-like distribution. The density of lump coal decreases in the process of dropping.