Resistance Vibration Analysis Of Supercritical Power Unit Water Service Pipe

As the power industry of our country develops at full speed, the high-pressure unit of high temperature of large capacity has already become the main unit of the power plant. Because of the improvement of the parameters, the mechanical vibration transmission of main and complement equipment, the large change of operation state of working medium and the assigning way in every main pipeline, serious vibration phenomenon has taken place to some pipelines .These influence the normal open, stop and operation of the units directly.The high pressure water service pipe in power plant take the task to supply water to the boiler. Because the vibration of the pipeline by the open and stop of water pump ,and the change of operation state, pipeline and its connect equipment will be in danger. In order to guarantee the safe operation of the unit, dispel the accident potential, It is necessary to carry on further investigation and analysis on vibration formation mechanism of the pipeline.This article has consulted a large number of domestic and international relevant materials about the vibration of pipelines, had a deeper understanding of them for the reason , danger and the measure to disappear the vibration. It has described the relevant theories of pipeline finite element model and finite element vibration . It adopts the large-scale finite element analyze software MSC.MARC to carry on three-dimensional model for the service pipe in the power station. It analyzes the Natural frequency and mode shape of pipelines and assault motive force to respond in Steady state and transient state. The Result of calculation of the danger situation from the CFD, will be the boundary condition of the non-linear pressure for pipeline three-dimensional finite element model. The dynamic respondent of pipelines is analyzed, it applies certain basis for optimizing the assigning of pipelines and the running method of pipeline. Adopting different unit types that is the beam unit,shell unit and three-dimensional solid unit to compare and analyse the modal of the pipeline finite element model , analyzing inhesion characteristic of pipeline in different finite element,Offering more rational basis for the pipeline modeling. The article calculates the 1st to 10th-order natural frequency and goes on, analyzes to the 1st to 5th-order of mode shape , regards these as the basis of design for water service pipe in power stations.Carries on three-dimensional modeling for the water service pipe in the power plant. And the dynamic response is analyzed in the operating mode imitated for the pipeline. including the operating mode of fluid pressure changed equalityly and the specified steady state and the valve is closed fast which cause the pressure transient impact,discusses detailedly on the displacement responds and equivalent of stress distributed of pipe wall . And with the safe check of pipeline stress ,it comprehensive analyzes and compares the cause which effect the pipeline system vibration.The result of calculation indicates that the reason of pipe vibration caused by fluid change is not that the fluid pressure getting higher but that the impact caused by unsymmetrical distributing of pressure in the pipeline.By safe check of the pipe stress, it indicates that even if the the hoist pressure by the transient impact exceeds the rating pressure largely in pipeline,the pipeline stress is still lower than the permission stress in current thickness of the pipeline. the calculation indicates that the thickness of pipe wall is not the common reason for the pipeline accidents. we can considering to induce the unnecessary thickness of pipe wall for saving material from this conclusion.