A New Equation of State for CCS Pipeline Transport: Calibration of Mixing Rules for Binary Mixtures of CO2 with N2, O2 and H2

TL;DR

This paper develops a flexible, pressure-explicit equation of state for impure CO2, calibrated with experimental data for binary mixtures with N2, O2, and H2, to improve pipeline transport modeling in CCS applications.

Contribution

It introduces a general framework for deriving pressure-explicit EoS for impure CO2, enabling tailored models for different impurities and conditions relevant to CCS pipeline transport.

Findings

Achieves close agreement with experimental data for binary mixtures.

Demonstrates superior accuracy over GERG EoS for O2 and H2 mixtures.

Provides a flexible model applicable up to 16 MPa and 273K to the critical temperature.

Abstract

One of the aspects currently holding back commercial scale deployment of carbon capture and storage (CCS) is an accurate understanding of the thermodynamic behaviour of carbon dioxide and relevant impurities during the pipeline transport stage. In this article we develop a general framework for deriving pressure-explicit EoS for impure CO2. This flexible framework facilitates ongoing development of custom EoS in response to new data and computational applications. We use our method to generalise a recent EoS for pure CO2 [Demetriades et al. Proc IMechE Part E, 227 (2013) pp. 117] to binary mixtures with N2, O2 and H2, obtaining model parameters by fitting to experiments made under conditions relevant to CCS-pipeline transport. Our model pertains to pressures up to 16MPa and temperatures between 273K and the critical temperature of pure CO2. In this region, we achieve close agreement with experimental data. When compared to the GERG EoS, our EoS has a comparable level of agreement with CO2 -N2 VLE experiments and demonstrably superior agreement with the O2 and H2 VLE data. Finally, we discuss future options to improve the calibration of EoS and to deal with the sparsity of data for some impurities.