Engineering Proceedings (Oct 2023)

Simulation-Based Techno-Economic Assessment of a Water-Lean Solvent for Natural Gas Sweetening Technology

  • Abdulhameed Abenelo Idakwoji,
  • Petrus Nzerem,
  • Saheed Olanrewaju Issa

DOI
https://doi.org/10.3390/ASEC2023-15370
Journal volume & issue
Vol. 56, no. 1
p. 104

Abstract

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Water-lean solvents are thought to deliver promising benefits including enhanced mass transfer properties, increased absorption capacities, and lower solvent regeneration heat duties in the natural gas sweetening process. Acid gas (H2S and CO2) removal is an essential piece of the natural gas value chain due to its corrosive effect on pipeline and process equipment, its impact on the environment, and its reduction in methane heating value. A number of solvents have been used for this process in the past. However, the low acid gas pickup, high cost per unit separation, and high regeneration heat duties form the basis for which we considered a water-lean solvent in this study. This study employs ASPEN HYSIS V12.1 to model the natural gas sweetening process of a hypothetical non-associated sour gas well with a novel water-lean solvent (50% wt. MDEA + 30% wt. DIPA + 15% wt. DMSO + 5% wt. H2O). Theoretical solvent screening was carried out to select the most promising water-lean solvent, following a flowsheet design, modeling, and result validation. The process economic analysis was carried out using Aspen Process Economic Analyzer to determine the unit separation cost and profitability indicators. The results show that the solubility of CO2 was found to be lower in water-lean solvents. The mass transfer did not seem to improve. This was generally difficult to take into consideration and properly assess in Aspen as there are no literature data with DMSO to fit the model parameters. DMSO reacts with H2S, leading to a loss of solvent. However, the mass transfer improved with the physical co-solvent, and the acid gas solubility decreased, resulting in more solvent consumption and impacting the capital expenditure. Economic analysis showed that the equipment cost of the proposed solvent is 1.4 M USD/yr higher than that of the aqueous MDEA commercially in use. As such, it is not considered economically viable.

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