Investigation On The Economic Ratio Friction Of Supercritical Carbon Dioxide Pipeline Transportation

Conveying the CO₂ system is an important part of carbon capture,utilization and storage technologies.Large-scale,long-distance delivery of CO₂ is the preferred method of pipeline transportation,which CO₂ as a supercritical transport has more advantages.This article studies the specific friction affecting the economic benefits of supercritical CO₂ pipeline transportation.In this paper,the PR equation was selected and the NIST Refprop database was called by Matlab to calculate the physical properties such as density,viscosity,thermal conductivity,specific heat at constant pressure and compressibility of pure CO₂,CO₂-N₂and CO₂-SO₂.In the supercritical area,the density,viscosity and thermal conductivity increase with the increase of pressure,but the Increase of amplitude gradually decreases;with the increase of temperature,the Increase of amplitude gradually decreases.Near the critical point,the constant pressure increases compared to the heat process,and the maximum value exists.The compression coefficient has the minimum value at about10MPa.Compared with SO₂,the effect of N₂ on the physical properties of the CO₂mixture is greater.To ensure that the CO₂ containing impurities is in a supercritical state,the pressure and temperature in the tube are determined to be no less than 8.17MPa and33.46 C,respectively.The model was used to calculate the pipe diameter.The design code of pipelines was used to calculate the pipe wall thickness.Determining the Gnielinski correlation and Churchill correlation as CO₂ in the supercritical state flow heat transfer correlation and tube friction resistance coefficient correlation.Aiming at a power plant,the calculation of frictional drag coefficient and specific friction of pipe length of 200km is carried out.The calculation takes into account the variation of pipe roughness,pipe diameter and flow rate,and obtains the fitting relation of the specific friction with the pipe length.Taking the minimum cost of initial construction investment and operation cost as the objective function,a mathematical model of economic friction resistance of supercritical CO₂ was established.The specific friction of initial temperature 45⁵5?and initial pressure 10¹9MPa was calculated.The specific friction increases monotonically with the increase of the initial temperature and decreases monotonically with the increase of the initial pressure.The maximum safe transport distance varies with the initial temperature,existing a maximum with the initial pressure increases monotonically.The calculation results of the ratio friction of 0.45,0.50,0.55 and 0.60 m show that the effect of changing the diameter on the friction is obvious.Increasing the diameter will greatly reduce the specific resistance,but the decreasing amplitude decreases with the increase of the diameter is light.Owing to increasing the diameter will reduce the specific resistance,at the same time the initial investment also increase,so changing the diameter will increase economic efficiency,but also together with the economic friction than the mathematical model for further analysis.Finally,based on the above results,the process of determining the optimal economic friction ratio is given.