Combined energy consumption and CO2 capture management: Improved acid gas removal process integrated with CO2 liquefaction

Highlights: • A novel Int-Rectisol process integrated with CO₂ liquefaction was proposed. • The new process decreased energy consumption from 389.1 MJ to 204.3 MJ for capturing 1 kg of CO₂. • The new process improved the CO₂ capture rate from 46.7% to 85% and decreased the exergy destruction by 20.95 MW. • The new process reduced the capital investment and the total product cost by 12.4% and 8.7%, respectively. Energy management is always facing a trade-off among the constrains of efficiency, energy consumption and CO₂ capture rate. For example, the Rectisol wash is a promising and efficient purification process for acid gas removal. However, this process has the problems of high cold energy consumption and low CO₂ capture rate. To solve the problems, this paper proposed an improved integrated Rectisol (Int-Rectisol) process with CO₂ partial liquefaction. This paper demonstrated how to comprehensively reduce the energy consumption by liquefying part of the CO₂ from the treated syngas before absorption. The decreased CO₂ concentration in the syngas consequently reduced the methanol solvent consumption and regeneration in the process. Meanwhile, less solvent circulation and regeneration further reduced the energy consumption of the overall process. Process modeling and simulation was conducted in Aspen Plus. The techno-economic performance was then evaluated and compared with the conventional process. The results showed that the solvent circulation in the Int-Rectisol process reduced by 46.5% and the energy consumption decreased from 389.1 MJ to 204.3 MJ for capturing 1 kg of CO₂. Meanwhile, the CO₂ capture rate also increased from 46.7% to 85%. The exergy analysis showed that the exergy destruction in the Int-Rectisol was 20.95 MW less than the Rectisol process. As for the economic benefit, the Int-Rectisol process reduced the total capital investment and the total product cost by 12.4% and 8.7%, respectively.