【作者】 金亮；

【导师】 金志江；

【作者基本信息】 浙江大学 ， 化学工程， 2018， 硕士

【摘要】 随着国家重大能源工程的建设与发展,减温减压装置被广泛应用于热电联产工程,用来实现对高温高压过热蒸汽的压力及温度调节。减压阀作为减温减压装置的核心部件,传统的阀门结构与技术已无法满足目前国家重大工程高温、高压差、大流量等一系列复杂工况要求。因此,需要对现有的减压阀进行创新与改造。本文提出了一种针对高温高压过热蒸汽的二级减压角式减压阀,采用双层多孔笼罩及节流孔板作为节流元件,并对其压比特性及节流特性进行数值分析,主要的研究内容与成果有:(1)使用Inventor软件建立了高温高压过热蒸汽减压阀几何模型,使用Workbench对流道模型进行了网格划分。以520 ℃,10 MPa的过热蒸汽作为流动介质,针对不同减压比和不同阀芯开度的压比特性进行了数值研究,分析了压力、速度和温度等流动参数变化情况;从减压机理上分析了三个参数的变化规律;获得了该阀的流量特性。研究表明:阀门流道的压力变化主要发生在双层笼罩和节流孔板,且双层笼罩的压降效果要好于节流孔板的压降效果。该阀的理想流量特性近似于线性关系。随着减压比的减小,流道压力越平稳,双层笼罩的压降效果越好,湍流能量耗散减小;过热蒸汽始终保持较大的过热度,不会发生相变。(2)建立了不同入口流道直径、双层笼罩间距以及节流孔板位置的流道模型,并针对以上三个参数对高温高压过热蒸汽减压阀节流特性的影响进行数值研究。研究表明:入口流道直径对该阀的节流特性及出口流量没有显著影响。随着双层笼罩间距的增大,内笼罩孔出口处的高流速低温区域减小,节流孔板处的湍流能量耗散明显下降。随着节流孔板位置的下移,阀腔两侧的漩涡增大,最大速度减小,最低温度增大,湍流能量耗散增大。综上所述,大双层笼罩间距以及靠近内外笼罩的节流孔板位置布置使高温高压过热蒸汽减压阀压降节流效果更好,湍流能量耗散就越少。本文的研究成果对于掌握高温高压过热蒸汽减压阀流场流动特性,改善其节流效果具有重要的指导作用。更多还原

【Abstract】 Recently,with the development of national energy projects,pressure and temperature reducing devices are widely used in "Cogeneration" project to control the pressure and temperature of superheated steam.The pressure reducing valve work as the core component,its structure can not meet the requirements of high temperature,high pressure difference.Therefore,the structure of the pressure reducing valve should be improved and innovated based on the existing valve structures.In this paper,A novel pressure reducing valve for high temperature and pressure superheated steam which is the angle type,was presented.The double-deck porous shrouded valve core and the orifice plate are throttling components.The pressure ratios performances and throttle performances of the valve were investigated by numerical simulations.The main research and achievements are as follows:(1)The geometrical model were built by Inventor,and the mesh generation were completed by Workbench.The medium in the valve is compressible superheated steam,which is 520 β and 10 MPa,Under different pressure reducing ratios and valve openings,the pressure ratios performances and flow characteristic parameters like pressure,velocity and temperature,are analyzed.The change rules of pressure,velocity and temperature is studied based on decompression mechanism.It is shown that the pressure change mainly occurs in porous shrouded valve cores and the orifice plate,and the decompression performances of porous shrouded valve cores are better than the decompression performances of the orifice plate.The ideal flow characteristic of the valve has liner features.With the decrease of pressure reducing ratio,the pressure becomes more constant,the decompression performances of porous shrouded valve cores becomes more better,the turbulence energy dissipation decreases.With the decrease of valve opening,the decompression mainly occurs in porous shrouded valve cores and the turbulence energy dissipation increases.The temperature of the superheated steam keeps so high that it does not take place phase change.(2)The flow channel models about different inlet diameters,different gaps of the double-deck porous shrouded valve cores and different locations of the orifice plate were built.And the throttle performances of the valve were analyzed by numerical simulation from three aspects.It was shown that the inlet diameter has no effects on throttle performances and the outlet flux of the valve.With the decrease of the gap,high velocity low temperature area after the inner porous shrouded valve core decreases,the turbulence energy dissipation of the orifice plate decreases obviously.When the location of the orifice plate drops,vortexes on both sides of the valve chamber becomes bigger,the maximum velocity decreases,the minimum temperature increases,and the turbulent energy dissipation increases.In conclusion,big gap of the double-deck porous shrouded valve cores and the location of the orifice plate which is close to double-deck porous shrouded valve cores,can make the throttle performances of the valve better and the turbulent energy dissipation less.The work is helpful for understanding flow characteristics and improving throttle performances of the pressure reducing valve for high temperature and pressure superheated steam.更多还原