火管式余热锅炉管板冷却室内流动传热研究

Study of the Flow and Heat Transfer Characters in the Tube Sheet Cooling Chamber of a Fire Tube Waste Heat Boiler

气流床气化–废锅流程具有较高的热效率并可副产一定量蒸汽,适宜于整体气化联合循环(IGCC)发电或无需合成气变换的工况。文中对常用于气态/液体烃气流床气化的工业火锅式余热锅炉管板冷却室建立了三维数值模型。采用Realizable k-ε模型模拟了湍流流动过程,用离散坐标模型(DOM)计算了合成气辐射传热过程,耦合研究了流体与固体壁面间的流动和传热过程。考察了冷却水入口形式、冷却水流量和出口环隙宽度对冷却室内流动传热过程的影响。结果表明,3冷却水入口的形式能够有效改善合成气管水侧壁面的冷却效果,同时获得更均匀的冷却室内速度、温度分布。现有的2冷却水入口形式下,优化的冷却水质量流量为200 t/h。此外,在合成气管道的入口处加入刚玉套管能够使合成气管道壁面的最高温度降低106 K,有效保护合成气管端部。

Due to its high energy efficiency and steam production, the entrained-flow gasification process with the radiant and conductive cooler is suitable for the integrated gasification combined cycle （IGCC） or other processes without water gas shift unit. In this work, a 3D numerical model was established to study the characters of fluid dynamic and heat transfer of the tube sheet cooling chamber of a commercial scale fire-tube waste heat boiler, which was adopted in the gaseous/liquid hydrocarbon gasification process. The realizable k-ε model and discrete ordinate model （DOM） were employed to simulate the turbulence and syngas radiant heat transfer, respectively. The fluid-solid coupling analysis of flow and heat transfer was conducted. The effects of inlet types and mass flow of the cooling water and the width of the cooling water outlet on the velocity and temperature distribution were investigated. The results show that the 3 inlets of the cooling water is the most appropriate type in enhancing the cooling of syngas tube and generating more uniform distributions of velocity and temperature. To the 2 inlets type, the optimized mass flow of cooling water is 200t/h. Furthermore, with the addition of corundum tube in entrance of the syngas, the syngas tube can be efficiently protected by reducing the hotspot temperature by 106K.