Life Study On The M701-type Gas Turbine Waste Heat Boiler And The Heating Surface During The Hot Start Process

Gas turbine power plant works as the variable load unit, and the waste heat boiler start and stop working frequently, making the boiler drum on the risk of fatigue failure, which becomes a threatening for the power plant safety, economic operation.4 heating pipes will directly affect the safety of the normal operation of the boiler, so it's needed to make a security analyses on all of these parts.Using the large-scale finite element analysis software ANSYS, a waste heat boiler steam drum wall on the startup process and the main heating boiler tube surface temperature and stress were calculated and analyzed. The cycle of stress at the drum wall and down pipe joints, the drum wall temperature distribution and the time-varying temperature difference were obtained and so was the characteristic of the thermal stress changing during the hot start. In the end the fatigue life of the three boiler drums are obtained. It's concluded that the thermal stress have a significant effect on the fatigue life of the drum through the lower safety level of the mid pressure drum.Heating pipes work in a state of high temperature and pressure, the stress state will directly affect their safety. Determine the stress state in order to evaluate its safety has important practical significance for boiler's safely and economic operation.Through the temperature field and stress field calculation, the temperature and the stress distribution inside was obtained the tube s'safety evaluation was made. How many hours the heating pipes of the boiler can work safely is obtained. It seems that all of these surfaces have an longer safety life expect the reheater2 because of the vibration of the tube caused by improperly design.In the waste heat boiler, reheater2, located at the first heated surface module, directly bear to rumors gas scour. In this case, because of the existing of Karman Vortex Street, the stress in the tube horizontal direction (vertical direction of the boiler) will periodically change. In addition, the tube is still in the high temperatures of up to 600 degrees Celsius. Working at high temperature and alternating stress, the tube safety will be greatly impacted. This article uses the ANSYS finite element software to analyze the fatigue life on the tube of reheater2 at the first row under the effect of the Karman vortex street. According to the result, the safety life of the reheater2 is 2.54 years with no strengthening. When strengthening the middle of the tube, the tube can work as long as 46 years more or less.