四分仓回转式空气预热器三维数值分析

Numerical Analysis on Heat Transfer of Quad-section Rotary Air Heaters

针对四分仓回转式空气预热器实际运行中存在的低温腐蚀问题,基于CFD软件Fluent,将转子受热面温度定义为用户自定义标量(UDS)并求解标量方程,建立了四分仓回转式空气预热器的传热三维数值模型.以某300 MW循环流化床锅炉的四分仓空气预热器为例,模拟得到工质和受热面的三维温度分布,分析了转子热段和冷段受热面传热性能存在差异的原因.结果表明:受热面板型和板材的不同是造成热段、冷段受热面传热性能和传热量差异的主要原因;右二次风仓的热段入口处受热面是发生低温腐蚀的危险区域,使其壁温高于酸露点可有效减缓低温腐蚀.

To solve the problem of low-temperature corrosion existing in actual operation of quad-section rotary air heaters, a 3D heat transfer model was set up based on CFD software Fluent for the air heater by defining the rotor heat surface temperature as user-defined scalar （UDS） and by solving the scalar equa- tion. Taking the quad-section rotary air heater in a 300 MW circulating fluidized bed boiler as an example, the 3D temperature distribution of both working fluid and heater surface was simulated, while causes lead- ing to the difference of heat transfer performance between hot- and cold-section of the rotor were analyzed. Results show that the difference of heat transfer performance and capacity is mainly caused by different shapes and materials of the hot- and cold-section. Low-temperature corrosion is easy to happen in the heat surface at hot-section inlet of right secondary air side, where the metal temperature should be kept above acid dew point so as to retard the low-temperature corrosion.