掺氢天然气的管道输运特性仿真与分析

Simulation and analysis for pipeline transportation characteristics of hydrogen-enriched compressed natural gas

掺氢天然气(HCNG)输送是利用现有天然气管线实现氢气长距离运输的一种可行方案,天然气中因氢气的加入使得输运气体的物性发生明显变化,从而对管道的输运特性造成一定影响。本文对掺氢混合气的流动及换热过程进行了分析建模,对天然气掺氢管道的运行特性进行了计算分析,并在计算中使用物性快速计算公式代替BWRS方程进行物性求解以提高计算效率。根据计算结果,氢气与天然气混合气体的黏度、密度、体积热值和焦耳-汤姆逊效应系数随着掺氢比例的增加而下降,比热容和压缩因子随掺氢比例的增加而增加;在管道运行中,管输体积流量随掺氢比例的增加而上升,管道压降和管道管存随之下降,管道的能量流量先下降后在大掺氢比后略有回升;管道能量流量恒定时,管道出口压力先降低后略有升高;氢气的加入会削弱长输管线压降导致的温度降低;地面温度对于管输流量和能量流量影响较小。

Hydrogen-enriched compressed natural gas(HCNG)is a potential carrier for transporting hydrogen over long distances with existing natural gas pipelines.Mixing hydrogen with natural gas brings apparent changes of its physical properties,which affects the transporting characteristics in pipeline.In this calculation,the BWRS equation is replaced by a fast method formula to improve the calculation efficiency.The flow and heat transfer process of HCNG is modeled,and the operating characteristics of the HCNG pipeline are analyzed.According to the calculated results,the values of viscosity,density,calorific value and Joule-Thomson effect coefficient of HCNG decrease with hydrogen adding,but the specific heat capacity and the compression factor increase;the transporting volume flow rate increases with hydrogen adding,and the transporting pressure drop and the pipeline storage decrease;the energy flow rate decreases with low hydrogen mixing rate and then slightly increases with the large hydrogen mixing ratio.When the energy flow rate is constant,the outlet pressure of the pipeline first decreases and then slightly increases with the hydrogen ratio increasing;the addition of hydrogen weakens the temperature decrease caused by the pressure drop of long-distance pipeline.