Acid gas removal from natural gas using ionic liquids

Student thesis: Doctoral Thesis

Abstract

The growth in demand for natural gas accounted for almost half the increase in global energy consumption in 2018 and is projected to increase by more than 10% over the next five years. This is due to its abundancy, efficiency and lower carbon content compared to oil and coal. However, raw gas contains undesirable components, such as hydrogen sulphide and carbon dioxide, which must be removed before its delivery to end users because of their toxicity, corrosivity, flammability and poor heating value.Various technologies have been used for acid gas removal. Amine-based absorption is the most widely used technique; however, they are corrosive, volatile, degrade at high temperatures and highly energy intensive to regenerate. This study aims to improve pre-existing amine processes by reducing their energy consumption and environmental impact through the use of ionic liquids (ILs) and their blend with other physical solvents as an alternative to amines.The consequences of replacing an amine with ILs or a blend of ILs with other physical solvent in an existing amine unit are examined and found to be promising. A thermodynamic description of the IL mixtures needed to be developed to examine their use to replace amine solutions. The perturbed chain statistical association fluid theory (PC-SAFT) is selected as the thermodynamic model to represent the vapour liquid equilibrium of acid gases-IL systems.The solubility of gases in ILs was successfully described without the need for empirical binary interaction parameters, as was required in previous studies. Up to 47% and 7% of the regeneration energy and the total annual cost, respectively, were saved by using IL instead of amine, while up to 40% and 27% of the regeneration energy and the total annual cost, respectively, were saved by using a blend of IL with other physical solvent.
Date of Award11 Jun 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorLeo Lue (Supervisor) & Iain Burns (Supervisor)

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