CO_2 capturing from flue gases injected into the NDDCT: Feasibility study, exergy and economic investigation of simultaneously MEA-solvent chemical absorption and flue gas injection

摘要

There are several methods to reduce CO2 emissions, including optimization of energy consumption by increasing the efficiency of a powerplant, using renewable energy, and Carbon Capture Plant (CCP). In this study, the methods of increasing efficiency and the application of CCP have been performed simultaneously. To increase efficiency, the newly proposed method of Heat Recovery Steam Generator (HRSG) Flue-Gas Injection (FGI) into the Heller tower of the powerplant was developed. Then, the CO2 captured plant (using MEA chemical Absorption), which is embedded inside the Heller towers, was investigated. Energy and exergy analysis was performed for each component and finally for the whole powerplant under crosswind conditions.The results show that the addition of the CCP inside the tower will even reduce the efficiency of the base cycle by as much as 9%, and in windy conditions, this reduction will be even greater. However, by using the FGI in the Heller tower, the cycle efficiency will increase by 1%.The highest destruction of exergy (41% relatively) happened in the combustion chamber. The CCP had the second-highest exergy destruction, which was estimated to be about 22% for no injection mode and 20% for injection mode relatively. HRSG and the cooling tower had the highest exergy destruction after the CCP.Finally, in view of rising carbon prices in the coming years, among the three proposals, the second plan (FGI with CCP) is economically feasible from 2030 with a return-on-investment rate of 35.63% and the Net Present Value (NPV) of 142480. Moreover, this plan is worthwhile from the environmental point of view.