| Climate change is a common problem facing the world today,and achieving carbon neutrality has become an important goal of every country.Hydrogen energy is a clean,zero-carbon secondary energy source.The application of hydrogen energy is an important way to achieve deep emission reduction in the fields of industry,construction,electricity,and transportation.Using existing natural gas infrastructure to mix hydrogen can transport green hydrogen produced from renewable energy to end users through the natural gas pipeline network.Therefore,adding hydrogen to pipelines can not only solve the problem of large-scale renewable energy consumption,but also transport hydrogen efficiently and at low cost,so as to realize "hydrogen into ten thousand homes",which is an effective way to reduce the carbon emission intensity of natural gas utilization and ensure the safety of gas supply.In this paper,theoretical analysis and simulation analysis are carried out on the transmission capacity of natural gas long-distance pipeline and urban gas pipeline network under the condition of hydrogen mixing.The main research contents and conclusions are as follows:(1)Simulation research on hydrogen mixing in long-distance natural gas pipelines.When the compressor speed is constant,the characteristic curves of pressure ratio,shaft power and outlet pressure all move down with the increase of hydrogen doping ratio.Keep the pressure at the starting point of the pipeline constant,the larger the hydrogen mixing ratio,the smaller the pressure drop along the pipeline,the smaller the temperature drop,and the lower the gas transmission power.Increasing the starting pressure of the pipeline will effectively improve the gas transmission power.When the hydrogen-doped natural gas is transported under the layout of the original pressurizing station,the larger the hydrogen-mixing ratio,the lower the starting pressure of each pipe section.The pressure drop at the starting point of the pipeline caused by hydrogen mixing is not obvious in the pipe section with large elevation difference,and the pressure drop at the starting point of the pipeline caused by hydrogen mixing in the pipe section with small elevation difference is obvious.(2)Simulation research on hydrogen dosing in urban gas pipeline network.The interchangeability of hydrogen-doped natural gas was judged by methods such as Wobbe index,high calorific value,combustion potential and A.G.A index,and based on the standard GB-T13611-2018.It is comprehensively judged that the mixed gas can replace methane when the proportion of hydrogen mixing is 0% ≤ p ≤ 22%.A simulation model is established based on the existing gas pipeline network data in a certain area of Gao Bei Dian.Steady-state and transient hydraulic simulations were carried out for the pipeline network with hydrogen mixed.With the increase of the hydrogen dosing ratio and the gas consumption of the nodes,the pressure drop of the user nodes will be larger after hydrogen doping. |
