天然气调压器水合物冻堵的数值模拟分析

Numerical simulation of hydrate frozen block of natural gas regulator

冬季是北方城市高压燃气管网发生冻堵的多发期,为了解决天然气调压器冻堵问题,对天然气调压器水合物冻堵因素及形成进行定量研究。根据计算流体动力学理论,采用数值模拟方法对天然气流经调压器的压力变化进行数值模拟,进而定性与定量地分析冻堵的形成过程。模拟得到调压器前、后管道以及阀口处的压力分布图、速度分布图和速度矢量图。结果显示,阀口处速度增加,阀口前、后压力变化明显,漩涡位置清晰,这些与实际工程中发生的冻堵情况相符合。天然气在阀口处具有低温、高压、水分滞留、强烈扰动的特点,为水合物的形成提供了条件。结果表明:调压器阀口处是形成冻堵的薄弱部位,冻堵的形成是一个动态过程,同时也是一个加剧过程,一旦发生冻堵而没有采取及时的措施,那么冻堵情况就会越来越严重。

Winter is a frequent period when hydrate frozen block of natural gas regulator occurs in the high pressure gas pipeline network in northern cities.Influencing factors and the formation of hydrate frozen block of natural gas regulator are studied in this paper.According to computational fluid dynamics theory,numerical simulation was adopted to perform both qualitative and quantitative analysis.Simulation results were obtained for the pressure distribution,the velocity distribution and the velocity vector at the front and back,and valve of the regulator.Results indicate that the outlet velocity of the valve increases and pressure changes when natural gas flow through the regulator.In the meantime,the position of the vortex is clear.These results agree with the phenomenon of the frozen block in practical engineering.Natural gas in the valve port has characteristics of low temperature,high pressure,water retention and strong disturbance,which contribute to the formation of gas hydrate.The numerical simulation results clearly indicate that the valve is the weak part where ice forms.Frozen block is a dynamic process,which aggregates with time.Without immediate measures,the frozen block will become more and more serious.