The Study On The Oxide-scale Mechanism And Control Measures Of Supercritical Power Generation Unit

The problem of oxide-scale exfoliation is becoming more and more serious as the increasing of the working parameters of the steam turbine.The oxide-scale exfoliation not only can result in over temperature tube-burst,but also main steam valve jam as well as solid particle erosion,effecting the security and economy of power plant.Therefore,study on the oxide-scale exfoliation is important.The oxide-scale formation and spalling mechanism are analyzed.The actual maintenance data of some supercritical power plant are used to analyze the reason of oxide-scale spalling.In the boiler water system and high temperature heating surface at the same time,the oxide-scale of the skin,the formation of oxide skin is inevitable,and the formation rate and thickness of the material and temperature and pipe material has a direct relationship.When the boiler reaches a certain time when the heating surface oxide thickness will accumulate to the critical value off,due to the chemical structure of the o xide-scale in instability,when the change of temperature and pressure overload,it will lead to large-scale scale off.The prevention measures that connecting with operation adjustment and equipment retrofit are proposed.Results show that oxide-scale exfoliation is a universal problem which have great impact on the security and economy of power plant operation.The control measures for preventing oxide-scale is proposed according to operation adjustment and equipment retrofit.