超临界CFB锅炉水冷壁管分区段热应力分析

Compartmentalized Thermal Stress Analysis of Water-cooled Wall Tubes for Supercritical CFB Boilers

为确保循环流化床锅炉水冷壁的正常运行,以避免发生蠕变变形、高温腐蚀等生产事故。以600 MW超临界循环流化床(circulating fluidized bed,CFB)锅炉为研究对象,建立了水冷壁温度应力场数值模型。并利用分区段炉膛热力计算理论和新IAPWS-IF97公式,对运行状态中水冷壁分区段进行壁温和热应力分析。结果表明:各区段管壁温度与应力场分布变化一致,但由于工质焓值和高温烟气的交叉作用,区段5存在最高壁温与最大热应力。进一步对区段5进行传热恶化分析可得,管壁最高温度部位发生转移,且壁温与热应力最大值皆超过设计值,可能导致水冷管爆管或断裂。随后针对安全隐患,通过数值模拟方法从降低局部热负荷和控制质量流速的角度来防止锅炉传热恶化,为锅炉安全监测提供了有效建议与防治手段。

In order to ensure the normal operation of water-cooled walls of CFB(circulating fluidized bed)boilers,to avoid the occurrence of creep deformation,high temperature corrosion and other production accidents.A numerical model of the water-cooled wall temperature stress field was developed for a 600 MW supercritical CFB boiler.And the wall temperature and thermal stress analysis of the water-cooled wall zoned section in the operating condition was carried out by using the theory of thermal calculation of the furnace chamber of the zoned section and the new IAPWS-IF97 formula.The results show that the distribution of wall temperature and stress field in each section is consistent,but due to the interaction of enthalpy and high-temperature flue gas,section 5 has the highest wall temperature and the maximum thermal stress.Further analysis of the heat transfer deterioration of section 5 shows that the maximum temperature of the pipe wall is shifted,and both the wall temperature and thermal stress exceed the design value,which may lead to water-cooled tube rupture or fracture.Subsequently,for safety hazards,numerical simulation methods are used to prevent boiler heat transfer deterioration from the perspectives of reducing local heat load and controlling mass flow rate,which provides effective suggestions and means of prevention and control for the safety monitoring of the boiler.