气流床气化炉壁面熔渣行为模拟

NUMERICAL SIMULATION OF SLAG BEHAVIOR IN ENTRAINED-FLOW COAL GASIFIER

本文对气流床煤气化炉内高温合成气和壁面渣层的流动与传热传质过程进行了分析,建立了渣层流动,传热传质和相变数理模型,采用VOF方法对渣层和气体之间自由界面进行追踪,采用射线追踪方法(DTRM)计算辐射换热,采用焓法计算渣层相变,熔融态渣滴在渣层表面的沉积通过源项引入。应用所建立的数学模型对实验室规模的Texaco煤气化炉进行了模拟。结果表明:气化炉壁面换热系数从上到下先增加再减少最后再增加;炉膛温度升高,固态渣层厚度减少;壁面温度升高,固态渣层厚度减少。

Based on the analyses of the flow and heat and mass transfer of high temperature syngas and slag layer, physical and mathematic models were proposed. VOF model was used to trace the free surface between the slag layer and the syngas. DTRM model was used to calculate the radiation heat transfer in the gasifier. The effects of the deposition of melted ash particle on the surface between the slag layer and the syngas were introduced by source terms. The model was applied to simulate flow and heat and mass transfer in a lab-scale Texaco gasifier. The results indicated that the heat transfer coefficient on the wall shows a trend of increase at the first, and then decrease, and finally increase from top to bottom along the wall of gasifier. The thickness of solid slag layer decreases with the increase of hearth temperature and/or wall temperature.