超临界及超超临界锅炉水冷壁壁温偏差研究

根据国内超临界锅炉的实际运行数据和超超临界锅炉的设计数据,研究了影响其水冷壁壁温偏差的主要因素。重点研究了水冷壁受热偏差、质量流率、工质焓增、变压运行、工质热物理特性等对于螺旋管圈水冷壁和垂直管屏水冷壁壁温偏差的影响关系；分析了控制超超临界锅炉水冷壁壁温偏差的技术措施：采用内螺纹管,降低水冷壁管外烟气侧热负荷和热偏差,适度控制质量流率的裕量,合理控制下辐射区和上辐射区水冷壁的工质焓增,采用节流圈调节流量偏差和利用垂直管屏在低质量流率下的正流量补偿特性等措施,可有效控制超临界和超超临界锅炉水冷壁的壁温偏差。

Research on the water wall temperature excursion in the supercritical and ultra supercritical boilers

The main factors affect wall temperature excursion of the water wall in supercritical boiler and Ultra-supercritical boiler have been analyzed based on the practical data in supercritical boiler and on the design data in Ultra-supercritical Boilers,especially the impacts on the wall temperature deviation of spiral wall tube coils and vertical tube plates.The above mentioned factors include the heat transfer deviation,mass flow rate,enthalpy rise of steam,variable-pressure operation and thermophysical properties,etc.In addition,the control measures against the wall temperature deviation in Ultra-supercritical Boiler were introduced.It means the introducing of internal-threaded tubes,reducing the gas side heat load and heat deviation outside the water wall,controlling the mass flow margin,controlling the added steam enthalpy between the lower and upper wall,using a choke coil to adjust the flow deviation and vertical tube plates for the positive flow compensation characteristic in case of low and so on.Thus the wall temperature deviation in the supercritical boiler and Ultra-supercritieal Boiler can be well controlled.