原料气液化压力对并联式氮膨胀制冷天然气液化工艺影响的模拟分析和优化

Simulation Analysis and Optimization of Effect of Feed Gas Liquefaction Pressure on Processing of Natural Gas Liquefaction by Parallel Nitrogen Expansion Refrigeration

本文分析了并联式氮膨胀制冷工艺中原料气分离器(S-1)气相压力,对换热器HEX-1中冷热曲线温差的影响提出了改进流程。采用遗传算法,以流程中对能耗、换热器冷热曲线最小温差以及液化天然气(LNG)流量有重大影响的13个参数作为决策变量,以单位能耗作为目标函数进行优化。通过㶲分析对比优化结果,优化结果表明,总㶲损失减少43.12 kW,其中以换热器㶲损失减少量最大,占总㶲损失减少量的26.13%。最后将优化结果与已有文献进行对比,对比结果显示LNG质量流量略微增加,单位能耗降低18.53%,㶲损失降低16.33%。

An improved process is proposed by analyzing the influence of gas phase pressure of the feed gas separator(S-1)on the temperature difference of HEX-1 heat and cold curve in the parallel nitrogen expansion refrigeration process.The process is optimized by genetic algorithm which use 13 parameters that have a greater impact on energy consumption,temperature difference between the heat and cold curves of the heat exchanger,and mass flow rate of the liquefied natural gas(LNG)are used as decision variables and use unit energy consumption as the objective function.Then exergy analysis is performed to compare the optimization results,which showed that the total exergy loss is reduced by 43.12 kW,of which the exergy loss of the heat exchanger is the largest,accounting for 26.13% of the total exergy loss.Finally,the optimization results are compared with existing literature,showing that LNG mass flow increased slightly,unit energy consumption decreased by 18.53%,and exergic loss decreased by 16.33%.