Simulation and Optimization of Comprehensive 4e-Assessments of Carbon Dioxide Capture of Flue Gas by Water-Lean Solvent

Abstract

Amine-based chemisorption technology with water-lean solvent is a promising route towards low-cost CO2 capture. This paper proposes a process simulation and optimization strategy for CO2-rich solvent to reduce external steam consumption and increase the energy efficiency by split-flow heat exchange. Optimized water-lean amine-based solvent, composed of blend amines and physical solvent, was employed and its CO2 capture performance analyzed for a bench-scale continuous system. A rigorously validated process simulation method is proposed for operational optimization and comprehensive economic, exergy, environment, energy (4E) analysis of the capture process on an industrial scale. The experimental and simulation results indicated that the optimal ratio of split-flow was 0.55-0.70, with this ratio resulting in the reflux temperature increasing from 90 to 110 °C. The proportion of total energy duty that went to reaction heat was increased to 79.6% from 61% in the benchmark case; this increase was ascribed to the synergistic promotion of physical solvent and split-flow heat exchange configuration. The water-lean solvent could operate at a regeneration duty of 2.07 GJ/t CO2 with a total capture cost of US $50.40/t CO2 (27% lower than the benchmark value) from coal-fired flue gas. In summary, the net CO2 reduction can be increased by 28%, taking the utility heat-cold consumption into account. This research indicates a feasible method of taking full advantage of water-lean solvent to achieve efficient CO2 capture.

Keywords: carbon capture, water-lean solvent, heat exchange, energy consumption, process simulation