Research On Vibration Characteristic Of High Pressure-drop Multistage Steam Trap And Optimization

In the process of opening and closing and operating conditions of steam trap,because of the large pressure-drop in the front and rear valve,the high pressure drop that occurs when passing through the valve internals results in a dramatic change in the fluid flow state and a strong pressure pulsation.The high pressure induces fluid-induced vibration and It even causes serious damage to valves and piping systems.The multistage throttle structure is usually used to reduce the strong vibration of the trap,but there is a lack of relevant research on how to design the multistage throttling damping structure accurately.In view of the above problems,the following research were carried out:(1)The vital role of high-pressure down-steam hydrophobic regulating valve in steam pipeline system and the harmfulness of flow-induced vibration in steam pipeline were introduced,and the mechanism of valve flow-induced vibration was analyzed.According to the research methods and present situation of valve or pipeline flow induced vibration and multi-objective optimization at home and abroad,the relationship between throttle parameters of trap valve and valve flow-induced vibration and the necessity of multi-objective optimization of valve internal throttle were put forward.(2)The simplified method of fluid flow through the sleeve trap was given,and the steady flow field numerical simulation of the simplified model with diff erent opening spacing and different orifice forms was carried out by using CFX software.The different opening spacing and the characteristics of the flow field of the simplified model with different orifice forms also were analyzed by using CFX software.The excitation source information of the numerical simulation of the transient flow field was derived,which laid the groundwork for the subsequent numerical simulation of the fluid-induced vibration.(3)A process of simulating fluid-induced vibration by using CFD method and LMS Virtual.Lab software was introduced.The numerical simulation of the vibration field of different orifice plate model with different orifice forms was carried out,and the structural vibration information of different parameter model w as obtained.This paper also quantitatively analyzed effects of different stage spacings and different orifice edge forms on the fluid-induced vibration of the simplified model.(4)The principle of NSGA-? algorithm and the basic function of Isight software to realize the algorithm were introduced,and the structure of multistage throttle was designed.The concept of gap spacing ratio and space coefficient were put forward.Taking the two-stage depressurized porous plate as an example,taking the two factors of hole spacing and stage clearance as independent variables,based on NSGA-? algorithm,the optimization model was solved with the aim of vibration level and space optimization.The optimal parameters of the multistage throttle internals of the trap valve was obtained.The flow field and vibration characteristics of the model in the front and rear optimization were analyzed.A reference for the optimization of the multistage throttles was provided.The optimization model was solved.The above researches not only provide theoretical guidance and reference for vibration reduction design of multistage sleeve steam trap,but also provide reference for optimal design of other large pressure-drop multistage sleeve regulating valve.