Study On Causes Of Tube Explosion Of Stainless Steel Tube In Supercritical Unit Boiler And Preventive Measures

With the rapid development of China's power industry,thermal power plant boilers have been high into the parameters.With the November 2004 Huaneng Qinbei power plant in China's first 600MW supercritical unit coal-fired boiler production,marking the power generation of coal-fired unit boiler steam parameters formally into the supercritical.Boiler can run under supercritical parameters,the boiler parts of the steel material grade has a higher demand.Therefore,a large number of high-temperature components of the supercritical unit boiler are made of high strength and heat-resistant steel such as martensitic stainless steel(T/P91,etc.)and austenitic stainless steel(TP 347H,etc.).In this paper,through the investigation of the two cases of the explosion of the martensitic stainless steel pipe and the austenitic stainless steel pipe of the superheater of the power plant supercritical unit,the failure analysis method and means are used to carry out the macroscopic examination of the steel pipe sampling Analysis,mechanical performance test,hardness testing,metallographic inspection,etc.,were studied two causes of the occurrence of pipe accident,through failure analysis,targeted to put forward the appropriate preventive measures,in order to ensure the safety,stability,economic operation,To prevent the occurrence of such incidents to provide technical support.And the supercritical unit boiler heating surface with austenitic stainless steel pipe due to the pipe parts of the more serious intergranular corrosion phenomenon,and under the action of stress,intergranular corrosion cracking rapid development,resulting in pipe in the operation of the pipe accident.Through the failure analysis of the accident tube sample we can draw:Supercritical unit boiler heating surface with martensitic stainless steel tube tube is one of the main reasons for long-term over-temperature operation,long-term over-temperature mainly due to two aspects,one is the uneven combustion of the furnace surface The uneven heat caused by long-term over-temperature,the second is the hot side of the hot tube heat exchange lead to long-term over-temperature.Therefore,we can learn from the above two cases of explosion accident can be learned:First,the requirements of austenitic stainless steel pipe manufacturers in strict accordance with the requirements of the heat treatment process to carry out the solution after the solution treatment process,and to strictly enforce the product before the use of quality acceptance system,increase the quality of the factory before manufacturing sampling ratio.The second is to increase the heating surface of the temperature measurement points,to strengthen the operation of the heating surface tube temperature monitoring.So as to ensure the long-term safe and stable operation of the unit.