Application of the Thermodynamic Cycle to Assess the Energy Efficiency of Amine-Based Absorption of Carbon Capture

Abstract

The thermodynamic cycle, as a significant tool derived from equilibrium, could provide a reasonable and rapid energy profile of complicated energy systems. Such a function could strongly promote an in-depth and direct understanding of the energy conversion mechanism of cutting-edge industrial systems, e.g., carbon capture system (CCS) However, such applications of thermodynamics theory have not been widely accepted in the carbon capture sector, which may be one of the reasons why intensive energy consumption still obstructs large-scale commercialization of CCS. In this paper, a kind of thermodynamic cycle was developed as a tool to estimate the lowest regeneration heat (Qre) of a benchmark solvent (MEA) under typical conditions. Moreover, COPCO2, a new assessment indicator, was proposed firstly for energy-efficiency performance analysis of such a kind of CCS system. In addition to regeneration heat and second-law efficiency (η2nd), the developed COPCO2 was also integrated into the existing performance analysis framework, to assess the energy efficiency of an amine-based absorption system. Through variable parameter analysis, the higher CO2 concentration of the flue gas, the higher COPCO2, up to 2.80 in 16 vt% and the Qre was 2.82 GJ/t, when Rdes = 1 and ΔTheat-ex = 10 K. The η2nd was no more than 30% and decreased with the rise of the desorption temperature, which indicates the great potential of improvements of the energy efficiency.

Keywords

• thermodynamic cycle
• COP_CO₂
• amine-based absorption
• carbon capture
• regeneration heat
• second-law efficiency