Research On Throttle Temperature Drop Characteristics Of Throttle Valve In A Gas Gathering Station

The throttle valve is often used in the mining and gathering of high pressure gas.It is the core component of the ground gathering and transportation system.High pressure natural gas flow through the throttle valve,due to channel mutations produce Joule Thomson effect loads to low temperature,even ice blockage formed in the outlet of the throttle valve,the formation of hydrates has seriously affected the normal operation of gas gathering and transportation.Aiming at the ice blocking problem of throttle valve,the theoretical and numerical simulation methods are used respectively to study the throttling temperature drop characteristics of natural gas in throttle valve,The corresponding conclusion is obtained,which provides a reference theory to prevent the throttle valve form 'ice blockage' in the process of gathering and transportation.First of all,the characteristics of natural gas were discussed,for the natural gas,gas hydrate and ice were comparative analysis,the thermodynamic parameters of methane,the main component of natural gas are studied emphatically.The density of methane,the constant pressure ratio heat capacity,the dynamic viscosity and the thermal conductivity value are obtained at different pressure and temperature.Secondly,Joule-Thomson effect is usually expressed by Joule-Thomson coefficient,which is the main component of natural gas,such as methane,ethane,propane,nitrogen,carbon dioxide and hydrogen sulfide.Joule of methane under different pressure and temperature of the Joule-Thomson coefficient is calculated using four kinds of VDW,RK,SRK and PR equation of state respectively.And compared with the literature value,the optimal state equation suitable for calculating the Joule Thomson coefficient of natural gas is obtained.At the same time,the-Joule Thomson reversal curves of each gas are made by using the best equation and the relationship between the throttle and heat absorption are studied.Then,the double-layer cage type throttle valve is taken as the research object,and the three-dimensional model is established.The CFD software Fluent is applied to simulate the transient process,and the variation of temperature field,pressure field and velocity field of the throttle valve is internal flow field is analyzed.Under the different inlet and outlet pressure conditions,the temperature drop,pressure drop and Joule-Thomson coefficient at the orifice position in the throttle valve are obtained.Finally,under different ambient temperature,convective heat transfer and temperature field of Fluent couple automatic based on coupling analysis of the impact of ambient temperature on the gas temperature drop in the throttle valve,the variation of the orifice temperature drop,at different temperature and different inlet temperature and pressure drop of Joule-Thomson coefficient.The results show that the temperature caused by the throttling effect of throttle valve drop by MATALAB programming SRK state equation for calculation of Joule-Thomson coefficient maximum relative error,the minimum relative error and average relative error were 1.17%,0.26%and 0.91%,The temperature drop interval of main components in natural gas is obtained.Under normal temperature,each component of natural gas belongs to refrigerating gas,which is easy to cause large temperature change.The effect of gas pressure is greater than that of medium temperature on temperature drop.lt is found that the temperature,pressure and speed change trend at the location of throttling hole at x=-7.5mm,x=0mm,x=7.5mm and x=15mm is the same,but the location at x=22.5mm is quite different,so it is divided into two cases.The outlet pressure begins to decrease,and the pressure drop varies greatly at the throttle position,and the temperature drop is little.As the precipitation of hydrates more and more,the outlet pressure is getting smaller and smaller,and the pressure drop varies little,but the temperature drop varies greatly.As the precipitation of hydrates more and more,the outlet pressure is getting smaller and smaller,and the pressure drop varies little,but the temperature drop varies greatly.