Decoupled thermal-driven absorption-based CO2 capture into heat engine plus carbon pump: A new understanding with the case study. (1st November 2020)

• Record Type: Journal Article
• Authors: Zhao, Jun; Fu, Jianxin; Deng, Shuai; Wang, Junyao; Xu, Yaofeng
• Is Part Of: Energy. Volume 210(2020)
• Publication Date: 2020-11-01
• Subjects: Thermodynamic -- Carbon pump -- Absorption -- Carbon capture -- Ideal cycle -- Second law efficiency; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2020.118556
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: Absorption-based CO2 capture has been widely recognized as a mature technology for CO2 separation from industrial flue gas. However, the solvent regeneration process consumes a significant amount of energy. It is urgent to gain a deep understanding from a thermodynamic perspective about the underlying mechanism in the conversion of energy during the carbon separation process. The present study aims at developing a new decoupling model to physically visualize the "thermal energy-to-Gibbs free energy change" process in absorption-based CO2 capture technology. Firstly, an energy conversion path through the heat to work and finally to generalized chemical work is demonstrated. Secondly, a "heat engine-carbon pump" decoupling model is established with a related expression of energy conversion efficiency of ideal absorption-based CO2 capture. Lastly, the energetic performances of typical pilot-scale absorption CO2 capture systems are evaluated through the second law efficiency. According to the results, the ideal cycle coefficient of performance can reach 0.898 at baseline condition of the case study, with a heat engine efficiency of 24.2% and carbon pump coefficient of 3.716. Generally, the second law efficiency of an actual system is less than 20%, while the Ammonia method has been adopted as the system with the highest efficiency of 27.39%. Highlights: A decoupling model of the "Heat engine - carbon pump" model is proposed and studied. The ideal cycle coefficient of performance η id serves as the energy efficiency ceiling of the absorption system. The second law efficiency of the pilot-scale system is calculated and analyzed.