350MW超临界循环流化床锅炉水冷壁热应力计算与蠕变寿命分析OA

Low-load and even ultra-low-load peaking operation has been the operating trend of supercritical circulating fluidized bed boilers.The water-cooled wall thermal deviation,heat transfer deterioration and other problems accompanying the operation under low load conditions aggravate the super-temperature creep damage of the tube wall,which affects its operation life.This paper takes an in-service supercritical circulating fluidized bed boiler as the research object,combines the actual operation data,constructs the simulation model of its temperature field and stress field,explores the distribution law of the temperature,deformation and thermal stress of the tube wall under the low load condition,normal heat transfer,heat transfer deterioration,and different thermal deviation,and evaluates the creep life of the water-cooled wall tubes under different temperatures and stress levels.The results show that when heat transfer deterioration occurs,the maximum temperature of the water-cooled wall tube shifts to the midpoint of the tube wall on the fireward side,and the maximum thermal stress still occurs at the contact point between the tube wall and the fins on the backward side;when the temperature deviation is more than 50℃,the maximum temperature,the maximum deformation,and the maximum thermal stress of the reference tube increase abruptly;and when the heat transfer deterioration occurs,the wall temperature of the tube wall at the danger point reaches 535℃,and the thermal stress reaches 258 MPa,which is close to the life limit of the water-cooled wall tube,so strict temperature control of the water-cooled wall should be prioritized.The results of the study provide a certain reference for the safe operation of supercritical circulating fluidized bed boilers at low load.