Modeling of CO2 Freeze-Out in the Processing of CO2-Rich Natural Gas

  • José Luiz de MedeirosEmail author
  • Ofélia de Queiroz Fernandes Araújo


Equations of state (EOS) have been developed for the petroleum and natural gas (NG) industries to predict phase behavior and properties of gas and liquid hydrocarbons on wide pressure–temperature domains. However, the processing of CO2-rich NG may create semi-cryogenic conditions leading to precipitation of solid CO2 (dry- ice), which is problematic in expanders, demethanizers, distillations, cold boxes, liquefied NG (LNG) facilities, and supersonic separators for CO2 removal. This phenomenon is denominated CO2 freeze-out. Semi-cryogenic separation of hydrocarbons and CO2 from CO2-rich NG can be designed to operate as desired, provided the CO2 solubility limit is not exceeded; otherwise, CO2 freezes out due to its high triple-point temperature relatively to hydrocarbons. Although EOS’s can predict vapor–liquid equilibrium (VLE), liquid–liquid equilibrium (LLE), and vapor–liquid–liquid equilibrium (VLLE), they must be complemented by thermodynamic models of solid CO2 and adequately managed by algorithms to predict CO2 freeze-out boundaries of constant total composition (CTC) streams on plane P × T. To accomplish this, it is necessary to solve solid–liquid equilibrium (SLE), solid–vapor equilibrium (SVE), and solid–vapor–liquid equilibrium (SVLE) with CO2 and light hydrocarbons. This chapter discusses property modeling of solid CO2 and numerical strategies for SLE-SVE-SVLE problems to predict freeze-out P × T boundaries of CTC CO2-rich NG streams.


  1. Donnelly, H.G., Katz, D.L.: Phase equilibria in the carbon dioxide—methane system. Ind. Eng. Chem. 46, 511 (1954)CrossRefGoogle Scholar
  2. Eggeman, T., Chafin, S.: Pitfalls of CO2 freezing prediction. Presented at the 82nd annual convention of the gas processors association. San Antonio, Texas, 10 Mar 2003Google Scholar
  3. Eggeman, T., Chafin, S.: Beware the pitfalls of CO2 freezing prediction. Chem. Eng. Prog. 101, 39–44 (2005)Google Scholar
  4. Giraldo, C.A., Clarke, M.A., Trebble, M.A.: Prediction of CO2 freezeout conditions and CO2 hydrate formation conditions with a single equation of state. Chem. Eng. Commun. 197(4), 571–583 (2010)CrossRefGoogle Scholar
  5. Hlavinka, M.W., Hernandez, V.N., McCartney, D.: Proper Interpretation of Freezing and Hydrate Prediction Results from Process Simulation. Bryan Research & Engineering, Inc. (2006)Google Scholar
  6. Im, U.K., Kurata, F.: Phase equilibrium of carbon dioxide and light paraffins in presence of solid carbon dioxide. J. Chem. Eng. Data 16(3), 295–299 (1971)CrossRefGoogle Scholar
  7. Lavik, V.F.: Freeze out in natural gas systems. Master of Science in Product Design and Manufacturing, Norwegian University of Science and Technology Department of Energy and Process Engineering (2009)Google Scholar
  8. Reid, R., Prausnitz, J., Poling, B.: The Properties of Gases and Liquids, 4th edn. McGraw-Hill Book Company, New York, USA (1987)Google Scholar
  9. Salim, P.: A modified Trebble-Bishnoi equation of state. M.Sc. thesis, University of Calgary (1990)Google Scholar
  10. Salim, P., Trebble, M.A.: Modeling of solid phases in thermodynamic calculations via translation of a cubic equation of state at the triple point. Fluid Phase Equilib. 93, 75–99 (1994)CrossRefGoogle Scholar
  11. Span, R., Wagner, W.: A new equation of state for carbon dioxide covering the fluid region from the triple-point temperature to 1100 K at pressures up to 800 MPa. J. Phys. Chem. Ref. Data 25(6), 1509–1596 (1996)CrossRefGoogle Scholar
  12. Trusler, J.P.M.: Equation of state for solid phase I of carbon dioxide valid for temperatures up to 800 K and pressures up to 12 GPa. J. Phys. Chem. Ref. Data 40(4), 043105 (2011)CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • José Luiz de Medeiros
    • 1
    Email author
  • Ofélia de Queiroz Fernandes Araújo
    • 1
  1. 1.Escola de QuímicaFederal University of Rio de Janeiro (UFRJ)Rio de JaneiroBrazil

Personalised recommendations