In recent years

thermal power units have frequently participated in peak shaving to build a new type of power system with new energy as the theme. Accidents of pipeline weld cracking and failure often occur. The welds on both sides of the intersection between the pipeline behind the intermediate pressure bypass valve and the condenser casing frequently crack. The opening area of the muffler pipeline also frequently crack. The heat transfer process from the pipeline behind the medium pressure bypass valve to the condenser muffler is studied by using the finite element method

The distribution of thermal stress under normal and peak shaving conditions was compared.To investigate the causes of the problem

a comprehensive calculation model for the medium pressure bypass pipeline is first established to obtain the distribution of primary and secondary stresses in the pipeline under normal working conditions

as well as the displacement and bearing values of each node. The finite element method is used to study the heat conduction process from the local medium pressure bypass valve to the condenser silencer pipeline.The thermal stress distribution under normal and peak shaving conditions is studied. The results indicate that under peak shaving conditions

the poor atomization effect of the nozzle results in severe water entrainment in the steam

The temperature difference between the pipeline behind the bypass valve and the pipeline of the condenser muffler is larger and repeated operation and shutdown of the desuper heating water cause thermal fatigue fracture of the weld seam and the opening area.