Construction and optimization of a waste heat and off-peak operation-assisted absorption carbon capture system

Carbon capture and storage can reduce the carbon emission directly and effectively. Absorption carbon capture (ACC) is currently the most promising way to remove CO2 from coal-fired power plant, yet the main drawback is the excessive thermal energy consumption for the regeneration process. In this study, a new ACC system that utilizing the low-grade waste heat to generate steam has been proposed, in which system the steam is compressed to increase the saturation temperature to satisfy the thermal energy grade demand of the absorbent regeneration. Heat pump is introduced to increase the inlet pressure and enhance the energy and economic effect of vapor compression and R245fa is found suitable for the system. The vapor generating work can be controlled below 200 kWh t−1 when Twh is higher than 60°C, and COPvg can be higher than 3.5 for situations of Ttag,sat not exceeding 130°C. The energy performance and economic analysis of the proposed ACC system driven by the new vapor generation method is analyzed. Off-peak operation by ASS shows good economic effect, the operating cost for the regeneration process of carbon capture is only 69.70 CNY t−1 CO2 under the worst condition and far below the traditional heating method. The new heat supply method for carbon capture presents reasonable energy and economic performance, which is shown suitable for peak shifting of the power grid.