A New Extended Corresponding States Equation of State for Modelling CO2-Water Thermodynamics - A Compromise for CFD

This PhD work is part of the CO2 Dynamics project in collaboration with Sintef Energy. We investigated the importance of accurate modelling of CO2 thermodynamic properties for process design. The study was conducted for the application of depressurization of a CO2 transport pipeline. In the study we investigated pure CO2 and CO2 mixtures, including the polar mixture of CO2 water. The study was conducted over pairs of pressure-temperature (PT) complying with two sets of experimental pipeline depressurization data. The results showed a significant impact of the quality of used equation of state (EoS), and the presence of impurities on the predicted thermodynamic behavior and speed of sound. Moreover, we conducted research on the capabilities of the extended corresponding states (ECS) EoS SPUNG when dealing with CO2 water mixtures. The SPUNG EoS was chosen as it was shown earlier to be a very promising EoS for Carbon Capture and Storage (CCS) non-polar mixtures. We started with a preliminary study followed by a detailed study that showed the potentials and limitations of the method. We also investigated the possibilities to improve or extend the limitations of the SPUNG EoS by changing the reference fluid. The found disadvantages of SPUNG EoS when dealing with CO2 water mixtures were that it poorly predicted the water-rich phase (even though better than SRK, and SRK-HV) and the CO2 solubility at wide range of conditions. As part of the investigation of the potential of the method, we conducted a reference fluid sensitivity study, which revealed a significant dependency of the density predictions on the chosen reference fluid. Within the set of hydrocarbons, the heavier the hydrocarbon was, the better it predicted the water-rich phase density. However, the reference fluid was found not to play a significant role in phase equilibrium capture. The prediction of phase equilibrium properties was more influenced by the mixing rule used in the approach of calculating the scale factors. Based on these systematic assessments, a new ECS approach was developed, which preserved the advantages of the SPUNG EoS but eliminated the limitations. The proposed EoS accurately captures the phase equilibrium and densities of the CO2 water systems at wide set of conditions of pressure, temperature and composition. The new model is an ECS that uses Bender’s 20-parameter MBWR as a reference equation, and SRK-HV as bases to the approach used to calculate the shape factors for scaling. The recommended reference fluids were NH3, R23, and R503 with parameters of Polt. All the evaluations in the presented articles were compared to large covering set of experimental data. Since one major advantage of the ECS based approaches is the good capture of transport properties, future work should assess the new model accuracy for predicting the CO2 water

[1]  Mukund R. Patel,et al.  Experimental densities and derived thermodynamic properties for carbon dioxide-water mixtures , 1988 .

[2]  J. W. Leach,et al.  Use of molecular shape factors in vapor‐liquid equilibrium calculations with the corresponding states principle , 1968 .

[3]  N. Dahmen,et al.  Density of Water + Carbon Dioxide at Elevated Pressures: Measurements and Correlation , 2004 .

[4]  J. Trusler,et al.  Shape factors for the light hydrocarbons , 1998 .

[5]  Jinyue Yan,et al.  Impacts of equations of state (EOS) and impurities on the volume calculation of CO2 mixtures in the applications of CO2 capture and storage (CCS) processes , 2009 .

[6]  Dominique Richon,et al.  Vapour-liquid equilibria in the carbon dioxide-water system, measurement and modelling from 278.2 to 318.2K , 2004 .

[7]  J. E. Coon,et al.  A cubic equation of state with a new alpha function and a new mixing rule , 1991 .

[8]  J. C. Seitz,et al.  The CO2-H2O system. I. Experimental determination of volumetric properties at 400°C, 10–100 MPa , 1999 .

[9]  J. Ely,et al.  Thermophysical Properties of Fluids. II. Methane, Ethane, Propane, Isobutane, and Normal Butane , 1987 .

[10]  J. Mollerup.  Unification of the two-parameter equation of state and the principle of corresponding states , 1998 .

[11]  Ivar S. Ertesvåg,et al.  Modelling CO2 - water mixture thermodynamics using various equations of state (EoSs) with emphasis on the potential of the SPUNG EoS , 2014 .

[12]  D. Broseta,et al.  CO2/water interfacial tensions under pressure and temperature conditions of CO2 geological storage , 2007 .

[13]  D. Peng,et al.  A New Two-Constant Equation of State , 1976 .

[14]  R. Wiebe,et al.  The Binary System Carbon Dioxide-Water under Pressure. , 1941 .

[15]  M. McLinden,et al.  NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP, Version 9.1 | NIST , 2013 .

[16]  G. Kontogeorgis,et al.  Thirty Years with EoS/GE Models - What Have We Learned? , 2012 .

[17]  Ioannis N. Tsimpanogiannis,et al.  Thermodynamic modeling of the vapor–liquid equilibrium of the CO2/H2O mixture , 2009 .

[18]  Ivar S. Ertesvåg,et al.  Preliminary Evaluation of the SPUNG Equation of State for Modelling the Thermodynamic Properties of CO2-Water Mixtures , 2012 .

[19]  G. Soave.  Equilibrium constants from a modified Redlich-Kwong equation of state , 1972 .

[20]  Sigmund Clausen,et al.  Depressurization of a 50 km long 24 inches CO2 pipeline , 2012 .

[21]  T. R. Bott,et al.  The mutual solubilities of water with supercritical and liquid carbon dioxides , 1992 .

[22]  O. Shoham,et al.  Equilibrated Interfacial Tension Data of the CO2–Water System at High Pressures and Moderate Temperatures , 2011 .

[23]  M. Michelsen,et al.  Modeling phase equilibria for acid gas mixtures using the CPA equation of state. Part II: Binary mix , 2011 .

[24]  Martin Peter Breil,et al.  Thermodynamic Models: Fundamental & Computational Aspects , 2008 .

[25]  Hailong Li,et al.  PVTxy properties of CO2 mixtures relevant for CO2 capture, transport and storage: Review of available experimental data and theoretical models , 2011 .

[26]  M. Huron,et al.  New mixing rules in simple equations of state for representing vapour-liquid equilibria of strongly non-ideal mixtures☆ , 1979 .

[27]  G. Sieder,et al.  High-pressure (vapor+liquid) equilibrium in binary mixtures of (carbon dioxide+water or acetic acid) at temperatures from 313 to 353 K , 2000 .

[28]  Dimitrios P. Tassios,et al.  An Equation of State for Associating Fluids , 1996 .

[29]  Mukund R. Patel,et al.  Thermophysical properties of gaseous carbon dioxide-water mixtures , 1987 .

[30]  R. Wiebe,et al.  The Solubility in Water of Carbon Dioxide at 50, 75 and 100°, at Pressures to 700 Atmospheres , 1939 .

[31]  Hailong Li,et al.  Evaluation of SPUNG* and Other Equations of State for Use in Carbon Capture and Storage Modelling , 2012 .

[32]  Ioannis G. Economou,et al.  Modeling the phase equilibria of a H2O–CO2 mixture with PC-SAFT and tPC-PSAFT equations of state , 2012 .

[33]  J. Ely,et al.  A Predictive, Exact Shape Factor Extended Corresponding States Model for Mixtures , 1990 .

[34]  George Jackson,et al.  New reference equation of state for associating liquids , 1990 .

[35]  W. Wagner,et al.  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 , 1996 .

[36]  Jean-Charles de Hemptinne,et al.  Industrial Requirements for Thermodynamics and Transport Properties , 2010 .

[37]  Jørgen Mollerup,et al.  Thermodynamic properties from corresponding states theory , 1980 .

[38]  G. Maurer,et al.  Das Dampf-Flüssigkeitsgleichgewicht des ternären Systems Ammoniak-Kohlendioxid-Wasser bei hohen Wassergehalten im Bereich zwischen 373 und 473 Kelvin , 1988 .

[39]  Michael L. Michelsen,et al.  On composition-dependent interaction coefficeints , 1990 .