氢气和天然气在静态混合器中的掺混模拟

Simulation study on the mixing of hydrogen and natural gas in static mixers

在氢能的众多输送方式中,将一定比例的氢气掺入天然气中并利用在役天然气管网进行输送,是一种经济高效的输氢方式。氢气和天然气的掺混均匀度直接影响到后续掺氢天然气的燃烧特性和用气安全,其中随动流量掺氢设备中的静态混合器是氢气和天然气的主要掺混场所,其有效性决定了混合气体的掺混均匀度。为此,采用数值模拟方法研究了氢气和甲烷在随动流量掺氢设备中不同类型静态混合器内和不同工况下的掺混过程,分析了静态混合器压力、掺氢比、气体流速、扰流元件类型、导流元件进气方向等主要因素对氢气和甲烷掺混效果的影响。研究结果表明:(1)静态混合器压力、掺氢比和流速的增大会提升氢气和甲烷的掺混均匀度,但影响较小;(2)扰流元件对掺混均匀度具有决定性作用,相同工况下LPD型静态混合器具有最好的气体混合效果,可基本实现氢气和甲烷完全混合;(3)当扰流元件合理布置时,导流元件的氢气进气方向对掺混均匀度几乎无影响。结论认为,该研究结果可为城镇掺氢天然气管网输送中氢气与天然气的高均匀度掺混技术提供技术参考,有助于氢能产业的快速安全发展。

Among many hydrogen transportation modes,an economical and efficient way is to blend hydrogen into natural gas at a certain proportion and transport it through in-service natural gas pipeline networks.The mixing uniformity of hydrogen and natural gas has a direct effect on the combustion performance and utilization safety of hydrogen-blended natural gas.The static mixer of the servo-flow-type hydrogen mixing equipment is the main mixing site of hydrogen and natural gas,whose effectiveness determines the mixing uniformity of the gas mixture.In this paper,the mixing process of hydrogen and methane in different types of static mixers of servo-flow-type hydrogen mixing equipment under different working conditions is numerically simulated.The influences of main factors on the mixing effect of hydrogen and methane are analyzed,such as the pressure of static mixer,the hydrogen blending ratio,the gas flow rate,the type of disturbance element,and the intake direction of diversion element.And the following research results are obtained.First,the mixing uniformity of hydrogen and methane is improved with the increase of static mixer pressure,hydrogen blending ratio and flow rate,but the effect is weak.Second,disturbance element has a decisive effect on the mixing uniformity.Under the same working conditions,the LPD-type static mixer has the best gas mixing performance,and can basically realize complete mixing of hydrogen and methane.Third,when the disturbance element is properly arranged,the influence of the hydrogen intake direction of the diversion element on the mixing uniformity is negligible.In conclusion,the research results can provide technical reference for the high-uniformity hydrogen and natural gas mixing technology of urban hydrogen-blended natural gas pipeline transportation,and is conducive to the rapid and safe development of hydrogen energy industry.