炉膛辐射传热数学模型及其仿真

A MODEL AND SIMULATION FOR RADIATIVE HEAT TRANSFER IN A BOILER FURNACE

为了准确计算炉膛内的辐射传热量,以辐射传热计算的假想面模型为基础,把锅炉炉膛沿高度方向分区,以炉膛内的燃烧与辐射传热过程为研究对象,建立了比较精确的炉内传热一维集总参数模型,推导出计算真实壁面和假想壁面有效辐射力的矩阵表达式, 然后通过求解介质的 能量方程,获得了炉内的一维温度分布以及各区段水冷壁的吸热量和热流密度。模型可以实现传热与燃烧子模型间的耦合求解,只需根据锅炉运行的外部参数便可实现炉内传热的自动计算。计算结果与其它文献三维模型的预测值非常一致,但由于模型采用了一维简化处理,收敛较快,可以满足电站实时仿真计算的需要。

To calculate heat transfer in a boiler furnace accurately, a one-dimensional model was developed based on the zone imaginary plane method (IPM). The furnace was divided into several zones along the gas path of the furnace, and the conservation equations of mass and energy for combustion and radiative heat transfer in each zone in the burner and burning-out regions were simplified using a lumped-parameter method. Furthermore the matrix formulations of effective emissive power for both real surfaces and imaginary planes were deduced. Then one-dimensional temperature profile along the gas path of the furnace was obtained by solving the mass and energy conservation equations with the iterative method. As a result, the radiative heat transfer and heat flux into water walls could be calculated. Since the heat transfer model was combined with a sub-model for combustion to estimate the heat production in each zone under different operating conditions of the boiler, the model could be used over a wide range of boiler load parameters without artificially setting computation inputs. The predicted results by the model were in good agreement with those by other three-dimensional models, and the model can be applied to perform real-time simulations due to its simplicity.