Exergy analysis of a conceptual CO2 capture process with an amine-based DES

Abstract

The energy efficiency of an absorption–desorption system for carbon dioxide capture from flue gas utilizing methyltriphenylphosphonium bromide-monoethanolamine (MEA) deep eutectic solvent is investigated in this article. According to the results, when the working pressure of the absorber column increases, the process becomes significantly exergy deficient, with an exergy loss of 7.63 MW compared to 5.7 MW for a normal MEA process. The majority of the exergy deficit is due to flue gas compression effort, which accounts for 99% of the total process exergy. The process’s exergy shortfall can be improved by lowering the absorber pressure from 10 to 3 atm, lowering the carbon dioxide removal efficiency from 90% to 60%, and increasing the solvent-to-gas ratio from 075 to 7.05. Furthermore, the incorporation of an energy recovery device could allow for an 80–90% reduction in the energy consumed by the gas compressor when running at 10 atm, from 5.7 to 1.2 MJ‧kg CO2 −1. With this adjustment, the deep eutectic solvent-based process can match or outperform the corresponding aqueous alkanolamine solvent-based process in terms of exergy destruction and specific energy consumption.

Keywords

• deep eutectic solvents
• co2 capture
• exergy analysis
• energy recovery