Study On The Noise Reduction Optimization Method Of A Steam Turbine Control Valve

Steam turbine is an indispensable power plant in the fields of thermal power,nuclear power,ships and industrial drag.The control valve is the main executive component of the steam turbine control system,and it works in the worst environment for a long time.On the one hand,the vibration noise of the steam turbine control valve affects the safety of the equipment and makes it fatigue damage,on the other hand,it also affects the physical and mental health of the operator.Therefore,it is of great significance to optimize the noise reduction of the steam turbine control valve.This paper first introduces the structure,working principle and concrete phenomena of high noise of a steam turbine control valve.Then it analyzes the unstable flow and noise characteristics of the control valve and determines the main factors of noise generation when the control valve is in low working condition.In combination with the commonly used noise control methods,an optimization scheme for a steam turbine control valve is proposed.Secondly,the flow field structure of a steam turbine control valve is analyzed by numerical simulation method,and the main factors affecting the noise characteristics of the control valve are found out,and the results are compared with the theoretical analysis results.Finally,the noise characteristics and flow characteristics of the control valve before and after optimization were studied by experimental methods.The high noise of the control valve and the vibration of the excitation valve stem mainly occur under the condition of small opening(the opening is not more than 10%),which is mainly caused by the impinging jet,in which the flow stability of the annular conical channel formed between the control valve disc and the valve seat is the worst,and even supersonic flow occurs.Therefore,in the optimization of vibration and noise reduction,the structure of the region is mainly adjusted to improve its flow field and reduce its flow loss.Since this topic is to optimize the control valve on a mature model,there are many constraints.While reducing noise,the flow performance cannot be reduced,and it cannot have a large impact on the peripheral system.Therefore,the valve seat of the control valve is mainly optimized,and finally the optimization scheme of “installing cross net frame long pipe valve seat” is adopted.In the course of the experimental study,in order to save costs,the test specimens were tested under air conditions,and then the test results were converted to steam conditions according to similar theory.The test results show that the noise of the steam turbine control valve is reduced by 1?8d B under different working conditions,and the area with higher noise of the header valve has been significantly improved,with an average reduction of about 5d B.The flow characteristics of the control valve also have a certain change.Below 8% relative lift,the flow coefficient of the optimized valve is about 5% lower than that of the prototype valve on average,and in the range of relative lift greater than 8% ? 25%,the optimized valve is higher than the original valve,and the maximum working condition is 36%.At the highest lift,the two are very close.The research results of this subject have important guiding significance for the optimization and improvement of this type of control valve and the development of the new type of control valve.