超超临界二次再热机组锅炉燃烧与水动力耦合计算方法研究

Research on coupling calculation method of combustion and hydrodynamics for water walls in ultra-supercritical double-reheat boilers

以某超超临界二次再热机组锅炉为研究对象,采用区域法对炉内空间和水冷壁面进行二维分区建模。将炉内燃烧放热过程与锅内流动换热过程进行耦合,并对其进行合理简化以便于工程化应用,得到了典型负荷工况下,螺旋管圈水冷壁的总体传热特性及壁温分布规律。结果表明:采用分级配风的炉膛,在沿高度方向上壁面热负荷均呈现出"双峰"分布,热负荷峰值接近400 kW/m^2;在炉宽方向上,水冷壁热负荷和壁温均呈现出中间高、两端低的抛物线形分布特征,主燃烧区的分布不均匀性要强于燃尽区,这说明炉内壁面热负荷是影响水冷壁管壁温度分布特性的重要因素;BMCR工况下主燃烧区的热流密度峰值可达到479.5 kW/m^2,壁温最高达到530.5℃。

Taking an ultra-supercritical double-reheat tower type boiler as the research object, zonal method was adopted to establish the two-dimensional discrete model for the space in furnace and the surface of the water wall. The model couples the combustion and radiative heat transfer in furnace with the hydrodynamics inside the water wall tube, then reasonably simplifies the process to adapt the engineering application. The overall heat transfer characteristics and wall tube temperature distribution of spiral water wall were simulated under typical working conditions. The results show that, a bimodal distribution of heat flux exists along the height of the furnace wall, while the peak value of heat flux approaches 400 kW/m^2. At the identical height, the values of heat flux and tube temperature on middle surface of the furnace exceed that on the comer of the furnace, and the non-uniformity in main combustion zone is obviously higher than that in over fire air zone. Under the BMCR condition, the maximum heat flux is almost up to 479.5 kW/m^2, while the highest tube temperature is about 530.5 ℃.