Effect of Impurities on CO₂ Properties session at the September 2014 Cardiff Biannual – Part 1

Written by Nor Daud from University College London, whose attendance at the UKCCSRC Cardiff Biannual Meeting was supported by the ECR Meeting Fund.

Dr Jie Ke – Phase equilibrium studies of impure CO₂ systems to underpin developments of CCS technologies

Dr Jie Ke, Research Fellow from the University of Nottingham, focuses on studying the impact of impurities in CO₂ streams such as N₂, H₂, Ar and H₂O on thermodynamic properties of the mixtures. The experimental work on binary and ternary mixtures is performed using a variety of high-pressure facilities that are developed at the University of Nottingham. The experimental data is validated using several types of equations of state (EoS) (Peng-Robinson with linear fit, Peng-Robinson with Boltzmann fit and GERG 2004/GERG 2008).

The findings show that the binary mixtures (CO₂ + 5 % H₂) have a more significant impact on phase envelopes compared to CO₂ + 5 % N₂ mixture. The presence of H₂ significantly increases the pressure required to form a homogeneous phase of impure CO₂. In addition, N₂ as non-condensable gas decreases the solubility of H₂O in CO₂ under dense condition relevant to CO₂ compression and transport. In terms of validation data using EoS, rigorous tests need to be performed in order to determine the best EoS in CCS application.

Dr Javier Rodríguez – gSAFT: Advanced physical properties for carbon capture and storage system modelling

Dr Javier Rodriguez is the lead developer of physical property models in gCCS, a modeling and simulation package for CCS system. The main objective of his presentation is to present the “end to end” CCS modeling tool, gSAFT, for the compression, transmission and injection subsystems within gCCS. This project is commissioned and co-funded by the Energy Technology Institute (ETI) (funding value c. $5m). The performance of gSAFT equations of state (EoS) on physical properties and phase diagrams of pure component and binary mixtures of CO₂ are studied and the results are validated using experimental data collected at the University of Nottingham. The study found an excellent degree of accuracy between the simulation and experimental data, concluding that gSAFT EoS is highly accurate and suitable for decision-making for CCS applications.

Professor Martin Trusler – Carbon dioxide properties and the role of impurities in the subsurface

Professor Martin Trusler is Professor of Thermodynamics at Imperial College London, lead investigator in the Qatar Carbonates and Carbon Storage Research Centre, and the Research Area Champion for CO₂ properties in the UK CCS Research Centre. During this session, Professor Martin presented the outline of on-going experimental work, focusing on reservoir conditions of temperature and pressure, and detail related to the role of impurities in the subsurface. At the end of his presentation, he also listed the projects that are still in progress including co-existing phase densities of CO₂ and water, the solubility of H₂S and SO2 in water and brine at high temperature and pressure, phase behavior study of CO₂-hydrocarbon mixtures, effect of impurities on CO₂-water and solubility of light hydrocarbons in water/brine.