超超临界锅炉折焰角斜坡积灰与塌灰计算分析 - -

超超临界燃煤发电技术是煤炭清洁利用的重要途径。超超临界锅炉中П型锅炉炉膛出口与水平烟道连接处的折焰角部位由于存在回流区极易形成积灰,严重影响锅炉安全运行。通过对超超临界燃煤锅炉折焰角积灰进行机理分析,包括灰粒与沉积层之间的黏结力和破坏灰粒沉积的力,建立折焰角积灰数学模型和塌灰预判模型,从而给出是否发生塌灰现象的预判结果,为电站安全运行及维护提供指导方案。该积灰与塌灰预判模型利用煤质相关参数、锅炉设计参数以及运行数据,得到烟气中煤灰颗粒的运动速度、深入沉积层深度和表面张力大小,从而定量计算出灰粒在折焰角斜面单位面积上的黏结力和灰粒对沉积层的冲击力,并根据单位面积上的黏结力、重力以及摩擦力之间的平衡关系得到折焰角部位理论最大积灰高度和实际最大积灰高度。当理论最大积灰高度大于实际最大积灰高度时,沉积层的摩擦力和黏结力大于重力沿折焰角斜面的分力,折焰角斜坡灰不会发生塌灰现象,反之,当理论最大积灰高度小于实际最大积灰高度时,则会发生塌灰现象。针对浙江浙能台州第二发电有限责任公司1 000 MW超超临界П型布置煤粉锅炉折焰角积灰与塌灰特性进行了计算分析,结果表明,当炉膛出口烟温为1 035℃,燃用设计煤种时,折焰角部位实际积灰高度为2. 48 m,小于重力平衡高度6. 69 m,该锅炉折焰角部位不会发生塌灰现象,折焰角设计及运行合理可行,超超临界锅炉折焰角斜坡积灰与塌灰预判模型对锅炉设计及优化运行具有参考价值。 Ultra-supercritical coal-fired power generation technology is an important way of coal clean utilization.Among the ultra-supercritical boilers,the furnace arch at the joint between the furnace outlet of the П type boiler and the horizontal flue is easy to form ash deposition due to the existence of the recirculation zone,which seriously affects the safe operation of the boiler.Through the mechanism analysis of the ash deposition of the furnace arch in the ultra-supercritical coal-fired boiler,including the adhesion force between the ash particle and the sediment and the force of destructing ash deposition the mathematical model of ash deposition of the furnace arch and the pre-judging model of ash collapse were established to give a prediction result of whether the ash collapse would occur,which could provide a guidance plan for the safe operation and maintenance of the power station.The ash deposition and ash collapse pre-judging model obtained the moving speed of the coal ash particles in the flue gas,the depth of the sediment layer and the surface tension based on adopting the coal quality parameters,boiler design parameters and operating data,so as to quantitatively calculate the adhesion force of ash particles in the per unit area of inclined plane of the furnace arch and the impact of the ash particles on sediments.The theoretical maximum ash deposition height and the actual maximum ash deposition height at the furnace arch position were obtained according to the equilibrium relationship among the adhesion force,gravity and frictional force in per unit area.When the theoretical maximum ash deposition height is greater than the actual maximum ash deposition height,the friction and adhesion force of the sediment layer are greater than the component force of gravity along the inclined plane of the furnace arch,and the ash deposition of the furnace arch does not collapse,otherwise,when the maximum ash deposition height is less than the actual maximum