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

Abstract

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.