天然气热值调控中掺混效果数值模拟研究

为了研究天然气热值调控过程的掺混效果,通过建立不同热值天然气掺混管路模型和划分网格,并基于ANSYS Fluent 16.0仿真软件对支管掺混和汇管掺混进行数值模拟研究。基于天然气掺混后管路内的速度场和组分场分布特点对天然气掺混后的效果进行对比分析。此外,通过了对天然气掺混后不同管径位置处掺混气体各组分百分比分析,并进行天然气掺混效果评价。结果表明:对于单管掺混流动,在掺混处拐角易发生低速滞流区域,掺混的效果不如汇管。对于单管掺混流动,在距离掺混中心位置15 D=3000mm处,掺混相对充分,各气体组分达到相对均匀状态,但在下游随着流动的发展,掺混仍在进行。对于汇管掺混流动,由于汇管的存在,改变了流体流动的方向,加剧了天然气流动的掺混,掺混效果较好。在汇管的出口,即支管的入口处,各气体组分已经达到相对均匀状态。

Numerical Simulation of the Mixing Effect in Natural Gas Calorific Value Control

In order to study the mixing effect of natural gas calorific value control process,this study establishes the pipeline models for the mixing of the natural gas with different calorific value,meshing for the pipeline models,and carries out the numerical simulation on the natural gas mixing for one branch pipe and one manifold by using ANSYS Fluent 16.0 software.Based on the distribution characteristics of the velocity field and the components field in pipeline after natural gas mixing,the effect of natural gas mixing is compared and analyzed.In addition,the effect of natural gas mixing is evaluated by analyzing the percentage of the gas components at different pipe diameter positions after natural gas mixing.The numerical results show that for the branch pipe mixing flow,the mixing effect is not as good as that of the manifold because of the lowspeed stagnation area at the mixing corner.For the branch pipe mixing flow,the mixing is relatively sufficient and the gas components are relatively uniform at the distance of 15 D=3000 mm from the mixing center.However,with the development of flow in the downstream,the mixing is still in progress.For the mixing flow of the manifold,the direction of fluid flow is changed due to the existence of the manifold,which aggravates the mixing of natural gas flow.Therefore,the mixing effect is better.At the outlet of the manifold,that is,the inlet of the branch pipe,the gas components have reached a relatively uniform state.