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Background
Industrial decarbonisation through CCUS and/or blue hydrogen, produced from natural gas with CCS, involves processing of numerous complex mixtures. Gas separations are crucial along with blending, compression, dehydration, transportation and geological storage. Thermodynamic properties are absolutely fundamental to these processes, many of which operate in regimes (of composition, temperature, pressure) not commonly encountered.
Although engineers have numerous thermodynamic models available, there is a lack of consistent and reliable models verified for the relevant conditions. Cubic equations of state (EoS), the workhorses of chemical engineering thermodynamics, can be reliable for predicting phase equilibria but are often inaccurate for phase properties such as density and enthalpy. Modern fundamental EoS, based on the multi-fluid Helmholtz energy approximation (MFHEA), offer substantial advantages.
Prof Martin Trusler
Principal Investigator
Imperial College London
Project Team
Imperial College London:
Dr Xuehui Wang
University of South Wales:
Jon Maddy
Aim
Building upon available high-accuracy Helmholtz EoS for pure substances, the MFHEA was developed for natural-gas systems [1], and has been extended to combustion gases including some CO2 -rich mixtures [2]; however, it is not currently parameterised for all key components in CCUS and hydrogen processes. This is especially true of mixtures containing hydrogen. Therefore, the first objective is to develop the parameter sets necessary to fully incorporate hydrogen as a mixture component within the MFHEA.
Currently, the MFHEA approach is not widely utilised in industry, with the exception of natural-gas properties required in custody transfer. Lack of familiarity and perceived concerns about computational demands are among the reasons. On the other hand, the shortcomings of traditional approaches are not widely recognised. Therefore, the second objective will be to undertake and publish case studies with industrial collaborators in which the role of thermodynamic models in CCUS and/or hydrogen processes is explored. Specifically, the task will be to contrast the predicted process performance using traditional thermodynamic models and the MFHEA. References: 1. Kunz, O.; Wagner, W. J. Chem. Eng. Data (2012), 57, 3032-3091 2. Gernert, J.; Span, R. J. Chem. Thermo. (2016) 93, 274-293
More Detail
CO2 hydrogenation is one of most notable carbon utilization technologies and, with blue or green hydrogen, it has great potential in industrial decarbonization. MeOH, CO2 and H2 are the main substances involved in these processes.
Thermodynamic properties and phase behavior are fundamental to the design, optimization and maintenance of the processes involved in CO2 hydrogenation. Unfortunately, there are still no consistent and reliable theoretical models covering wide operating regimes. The multi-fluid Helmholtz energy approximation (MFHEA) Equation of state has great advantages and the potential to represent the properties of these systems reliably. Nevertheless, it has not been fully parameterized and widely utilized outside of the natural gas and refrigeration industries.
Meet the Team
Team 1
Jon Maddy
University of South Wales
Team 1
Dr Xuehui Wang
Imperial College London
Team 1
Jon Maddy
University of South Wales
Team 1
Dr Xuehui Wang
Imperial College London
Case Study/Progress
- CO2 hydrogenation is an important way to address the carbon emission. To promote the design, optimization and maintenance of relating processes and systems, the accurate equation of state for these binaries covering wide range are critically needed.The multi-fluid Helmholtz energy approximation EoS could be a good candidate.
- Based on experimental data collected, two reducing parameters (γT and γV) are fitted and optimized while set the other two as unity. With new reducing parameters, the prediction of MFHEA agree well with the experimental VLE data. The calculation deviations of stature liquid density are within ±2%.
- Despite that, the current model can only predict data within a relative smaller range due to the data limitability. More data (including properties of homogenous phase, higher pressure/temperature accordingly with CO2 hydrogenation process) are still needed.
