天然气工业2024，Vol.44Issue(2)：145-155,11.DOI:10.3787/j.issn.1000-0976.2024.02.014
静置工况条件下掺氢天然气浓度分布规律
Concentration distribution pattern of hydrogen-blended natural gas under static operating conditions
摘要
Abstract
The use of in-service natural gas pipelines for hydrogen blending transportation has become a research hotspot and focus in the field of hydrogen energy and natural gas transportation.So far,however,there has always been controversy regarding whether hydrogen-blended natural gas(HBNG)can spontaneously stratify during pipeline transportation and shutdown static processes.In order to clarify this issue,this paper takes the extreme operating condition of HBNG being stationary in pipelines as an example to derive a mathematical model of HBNG concentration distribution under the action of gravity field based on the principle of thermodynamic minimum energy.Then,the mathematical model is solved using the Peng-Robinson real gas equation of state.Finally,the distribution patterns of hydrogen concentration in methane-hydrogen binary gas mixtures at four typical scenario heights and five hydrogen blending ratios are studied.And the following research results are obtained.First,under the influence of gravity,hydrogen concentration difference occurs between the top and bottom of the pipeline,but it is significantly affected by height difference.For horizontal pipelines at the meter level,natural gas risers in general urban buildings at dozens of meters level,and natural gas risers in high-rise buildings at the hundred-meter level,the variation of hydrogen concentration with height is slight and the hydrogen stratification can be completely ignored.Second,for HBNG pipelines with kilometer level drop,hydrogen stratification can still be ignored when the hydrogen blending ratio does not exceed 20%.However,when the hydrogen blending ratio is very high(such as 50%),the hydrogen concentration difference between the top and bottom of the pipeline exceeds 1%.In this case,it is necessary to evaluate whether hydrogen stratification can be ignored based on the actual engineering situations.Third,the concentration distribution pattern of each gas component with the drop height in a certain pipeline of the West-to-East Gas Transmission Project considering true gas composition,hydrogen blending ratio of 20%and pipeline drop of 200 m reveals that the hydrogen stratification in HBNG with such drop height can be ignored in practical engineering.In conclusion,for evenly mixed HBNG,it is most likely to stratify under extreme static conditions,so if there is no extreme kilometer drop and extreme high hydrogen blending ratio,stratification of HBNG pipelines can be completely ignored.This research result theoretically clarifies the current controversy regarding the stratification phenomenon in HBNG,which is of important guiding significance for the safe transportation of HBNG pipelines.关键词
掺氢天然气/氢分层/掺氢比/能量最小原理/静置工况Key words
Hydrogen-blended natural gas/Hydrogen stratification/Hydrogen blending ratio/Minimum energy principle/Static operating conditions引用本文复制引用
李敬法,宇波,苏越,刘翠伟,李玉星..静置工况条件下掺氢天然气浓度分布规律[J].天然气工业,2024,44(2):145-155,11.基金项目
国家重点研发计划项目"氢能技术"重点专项"中低压纯氢与掺氢燃气管输工艺与掺氢设备研发"(编号:2021YFB4001602)、国家自然科学基金项目"城镇掺氢燃气管道掺混/分层传质机理及高精度随动流量掺氢调控机制研究"(编号:52372311). （编号:2021YFB4001602）
