Calculation of Physical Parameters and Analysis of Temperature Fields of CO2 with Impurities Dry Gas Seal at Operating Points

As the most effective strategy to reduce CO2 emission, carbon capture, utilization and storage (CCUS) technology has become the focus of global attention under the background of “carbon emission peak, carbon neutrality”. For the centrifugal compressor dry gas seal applied in CCUS technology, the spiral groove dry gas seal was taken as the object, and CO2 with impurities was used as the lubricating medium. Based on the equation of state for combustion gases and combustion gas–like mixtures（EOS–CG）, the density, enthalpy, sound speed and Joule–Thomson coefficient of CO2 mixture were studied. With the consideration of the real gas effect, viscosity–temperature–pressure effect, choked flow effect, centrifugal inertia effect and convective heat transfer between lubricating gas and sealing face, based on the solution of the Reynolds equation, en-; ergy equation and heat conduction equation of sealing rings by the finite difference method, the pressure field, temperature field, opening force and leakage rate of the CO2 with impurities dry gas seal was analyzed. The results showed that the density of CO2 with impurities increases with the increase of the pressure, and the enthalpy, Joule–Thomson coefficient increases with the decrease of the pressure when temperature is constant. The density decreases with the increase of the temperature when pressure keeps constant while an opposite trend is obtained for enthalpy. The sound speed increases as temperature increases while Joule–Thomson coefficient reduces under the same pressure within a lower pressure condition. In addition, when entrance pressure is 12 MPa, inlet temperature is 380 K, rotating speed is 15000 r/min, outlet pressure is 1.9 MPa, the temperature difference between the inlet and outlet of gas film is about 23 K, and it is about 10 K for sealing ring end face. When the rotating speed, inlet pressure and inlet temperature are regarded as variables, the temperature of gas film and sealing rings increases with the increase of the rotating speed and the inlet temperature, respectively, but decreases with the increase of the inlet pressure. The opening force increases with the increasing of the rotating speed, inlet pressure and inlet temperature. The leakage rate decreases with the increase of the rotating speed and inlet temperature, and increases with the increase of the inlet pressure. © 2023 Editorial Department of Journal of Sichuan University. All rights reserved.