纯氢/掺氢天然气管道的减压与调压

Decompression and pressure regulation of pure hydrogen and hydrogen-enriched compressed natural gas pipelines

【目的】调压系统作为连接长输管道与城镇燃气管网的关键环节之一,在实现“氢进万家”中发挥着重要作用,然而氢气与天然气的物性差异会影响调压的工艺控制效果。【方法】采用纯氢/掺氢天然气减压调压实验与调压动态模拟相结合的方式,以稳压精度、响应时间、适用度函数作为判定减压调压系统稳压效果的依据,对掺氢比、流量波动周期、下游流量变化幅度、管输压力及PID参数进行了敏感性分析。【结果】(1)系统波动越频繁、气体流速越大,导致系统受到扰动后波动幅度越大,减压调压系统越不易实现稳压,需对管输纯氢或者掺氢天然气的高流速运动进行限制。(2)调压系统流量有正弦变化的波动,以稳压精度±1.5%为要求,开展减压调压实验时,PID比例参数、积分参数设定在1~2范围时,可基本实现纯氢/掺氢天然气在城镇燃气管道压力范围内的调压。(3)当管输气体流速相同时,纯氢的瞬时波动较天然气更为明显,控制系统的响应时间、适应度函数均随掺氢比的增大而逐渐增加;纯氢的压力瞬时波动可达到纯甲烷的1.15倍,控制系统的响应时间、适应度函数也分别增大为纯甲烷的1.13倍、2.68倍,当氢气与甲烷为相同比例参数、积分参数时,含氢气体更难实现稳压,可根据掺氢比适当降低积分参数或增大比例参数,实现与天然气相同甚至更好的稳压效果。【结论】研究成果可为纯氢/掺氢天然气管道的实际调压过程提供一定的理论参考。(图13,表3,参27)

[Objective] Pressure regulation systems,serving as one of the vital links between long-distance pipelines and urban gas pipeline networks,play a significant role in the successful implementation of the “Hydrogen Society” Program.However,the contrasting physical properties of hydrogen and natural gas impose challenges to the effectiveness of process control in pressure regulation.[Methods] This study employed a combined approach involving decompression and pressure regulation experiments conducted on pure hydrogen and hydrogen-enriched compressed natural gas(HCNG),along with dynamic simulations of pressure regulation.By establishing a foundation for assessing the pressure stabilization effect of the decompression and pressure regulation system,considering factors such as pressure stabilization accuracy,response time,and fitness function,a sensitivity analysis was performed to investigate the influence of various parameters,including hydrogen blending ratios,flow fluctuation cycles,downstream flow change ranges,pipeline transmission pressures,as well as proportional,integral,and derivative parameters(PID).[Results] The following results were obtained:(1) With more frequent disturbances,gas flow rates increased,leading to larger system fluctuation ranges.Consequently,achieving pressure stabilization became more challenging for the decompression and pressure regulation system.This finding highlighted the importance of restraining the movement of pure hydrogen and HCNG at high flow rates in transmission pipelines.(2) The flow rate of the pressure regulation system carried sinusoidal fluctuations.Setting the pressure stabilization accuracy at ±1.5% and the proportional and integral parameters within the range of 1 to 2,the decompression and pressure regulation experiments showed that the decompression and pressure regulation of pure hydrogen and HCNG could be substantially achieved within the required pressure range of urban gas pipelines.(3) Pure hydrogen exhibited greater instantaneous fluctuations compared to natural gas when flowing through pipelines at identical rates of transmission.As a consequence,the response time and adaptability function of the control system gradually increased with higher hydrogen blending ratios.Moreover,the instantaneous pressure fluctuation of pure hydrogen reached 1.15 times that of pure methane,resulting in a response time and adaptability function of the control system that increased to 1.13 and 2.68 times those of pure methane,respectively.Under the same proportional and integral parameters,it was more challenging to maintain the pressure stabilization for the hydrogen-containing gas.Hence,decreasing the integral parameter or increasing the proportional parameter proportionally to the hydrogen blending ratio is recommended,to attain the same or even better pressure stabilization effect as observed in natural gas scenarios.[Conclusion] The research findings provide theoretical insights to guide the pressure regulation practices of pipelines carrying pure hydrogen and HCNG.(13 Figures,3 Tables,27 References)