| Nowadays,the supply of fossil fuels is insufficient in the world.Hydrogen energy has become a new research hotspot because of its clean environmental protection and sustainable utilization.The development of hydrogen energy is also an important means to achieve the strategic goal of carbon neutral energy.The shortage of hydrogen transportation infrastructure restricts the development of hydrogen energy,and the cost of new dedicated hydrogen pipelines and infrastructure is high.At present,a large number of natural gas pipelines have been built in the world,which can inject hydrogen into the natural gas system.Using the existing natural gas pipelines to transport hydrogen doped natural gas(H2NG)is considered to be one of the effective ways to solve the obstacles of hydrogen energy development in the transitional era One.However,there is a significant difference in physical properties between hydrogen and methane,which is the main component of natural gas.The physicochemical properties of the mixed gas change after adding hydrogen,which also has a great impact on the hydraulic and thermal characteristics of the mixed gas in the pipeline.The transportation of hydrogen doped natural gas with different hydrogen ratios will have different degrees of impact on the operation of the pipeline network,and will also introduce new safety problems.Introducing Peng-Robinson real gas equation of state accurately predicts the thermodynamic properties of hydrogen doped natural gas,establishes a 1D flow and heat transfer model of gas pipeline,considers the influence of topography,environmental temperature and hydrogen doping ratio on the pipeline transportation process,and obtains the pipeline transportation rules under different pipeline inclination,environmental temperature and hydrogen doping ratio,as well as the influence on the layout of pressurization station Based on the natural gas pipeline,the model of existing pipeline network and station from the source point to the place of use is established,and the steady-state simulation calculation is carried out.The influence of transporting different hydrogen doped natural gas and injecting gas in the middle on the subsequent stations of the original pipeline network system is analyzed.From the perspective of enthalpy and enthalpy,the enthalpy flow is calculated by using userdefined variables The energy and energy of pipeline transportation process are analyzed.It is found that the density of the pipeline gas decreases,the specific heat increases,the viscosity decreases,and the enthalpy flow rate and enthalpy of the mixed gas also increase with the addition of hydrogen.When the natural gas pipeline is used to transport the hydrogen doped natural gas,the resistance loss of the same transportation distance can be reduced with the addition of hydrogen,and the gas transmission capacity and the distance between pressurization stations of the pipeline can be increased.If the original layout of pressurization stations is maintained,excessive pressure will be caused In case of pressurization,when the hydrogen ratio is lower than 30%,the pipeline efficiency will increase,and the intermediate gas injection will reduce the inlet pressure of subsequent pressurization station.In addition,in order to ensure the operation safety of gas transmission pipeline,ANSYS FLUENT software is used to simulate the decompression wave of hydrogen doped natural gas,and the decompression wave curves of different hydrogen doped natural gas are obtained.It is found that with the increase of hydrogen volume fraction,the decompression wave velocity curve gradually shifts to the right,and the crack arrest toughness of the pipeline will also decrease.This study will provide a useful reference for the design and safe operation of hydrogen doped natural gas pipeline pressurization station. |
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