Thermodynamic modelling of acid gas removal from natural gas using the Extended UNIQUAC model

- A robust model for representing thermodynamics of acid gas absorption from natural gas is presented.
- A unique set of optimized parameters accurately represent thermodynamic properties of H2S-CO2-CH4-MDEA-H2O system.
- For the first time the Extended UNIQUAC model has been applied for representing thermodynamics of the studied systems.

Thermodynamics of natural gas sweetening process needs to be known for proper design of natural gas treating plants. Absorption with aqueous N-Methyldiethanolamine is currently the most commonly used process for removal of acid gas (CO2 and H2S) impurities from natural gas. Model parameters for the Extended UNIQUAC model have already been determined by the same authors to calculate single acid gas solubility in aqueous MDEA. In this study, the model is further extended to estimate solubility of CO2 and H2S and their mixture in aqueous MDEA at high pressures with methane as a makeup gas.

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