新型双层笼套式节流阀流场数值模拟分析

Numerical Simulation Analysis of Flow Field of a New Double-layer Cage-sleeve Throttle Valve

笼套式节流阀是高压气井开采常用的关键装置之一。高压气体通过节流阀进行调压和调产,在低温高压的环境下,由于焦耳-汤姆逊效应的影响,流体流经节流孔处时温度较低,极易产生天然气水合物,影响天然气生产的正常运行。因此,节流阀的性能将直接影响生产的质量、成本和安全。传统的笼套式节流阀降压效果较差、节流效率较低、使用寿命较短。基于此,以新型双层笼套式节流阀为基本模型,采用计算流体力学(computational fluid dynamics,CFD)数值模拟方法对节流阀中天然气节流特性进行研究,并与传统笼套式节流阀的节流性能进行对比,在本文设置工况下,相比于传统笼套式节流阀,新型笼套式节流阀在节流孔局部的最低压力降低9.5%,最低温度提高7.8%,最大速度降低12.0%,更不易形成低温高压的水合物生成环境,且流体对结构的冲蚀作用更小,其总体性能优于传统式结构;同时研究得出了流体流动参数和节流孔结构参数的改变对新型笼套式节流阀节流性能的影响规律,对实际生产应用具有一定的指导作用。

The cage-type throttle valve is one of the critical devices commonly used in high-pressure gas well exploitation.Pressure regulation and production regulation of high-pressure gas are achieved through the application of throttle valve,and the cage-type throttle value under low-temperature and high-pressure is among the critical devices commonly applied in the exploitation of high pressure gas well.The pressure and production of high-pressure gas is regulated through throttle value.Under low-temperature and high-pressure environment,the influence of Joule-Thomson effect makes the temperature lower when the fluid flow through the throttling orifice,which makes it easier to produce natural gas hydrates,affecting the production of natural gas.Due to the influence of Joule-Thomson effect,the temperature is lower when fluid flows through the throttling orifice,which makes it easier to produce natural gas hydrates,affecting the normal operation of natural gas production.Therefore,the performance of throttle value will directly influence the quality,cost and safety of production.Traditional cage-type throttle value bears some disadvantages such as poor pressure reduction effect,low throttling efficiency,and short lifespan.So based upon this point,the new double-layer cage-type throttle valve is employed as the basic model.The method of CFD numerical simulation is adopted to study the throttling characteristics of natural gas in the throttle valve.Additionally,the throttling performance is compared with the traditional cage-type throttle valve.Under the operation mode set,compared with the traditional cage-type throttle valve,the minimum pressure of new cage-type throttle value in the local throttling orifice reduces by 9.5%,the minimum temperature increases by 7.8%,and the maximum speed drops by 12.0%,which makes it less likely to produce a low-temperature and high-pressure environment for hydrate formation.What’s more,the fluid in the new one has less erosion effect on the structure,thus its overall performance is better than the traditional structure.At the same time,the study figured out the influence law of changes in fluid flow parameters and the structure parameters of the throttling orifice on the throttling performance of new cage-type throttle value,which has a certain instructive implication for practical production and application.