High-efficiency power generation system with CO2 capture based on cascading coal gasification employing chemical recuperation

Abstract

Coal-based power generation systems combined with CO2 capture can generate clean, efficient, decarbonized electricity and have recently received significant attention. This study proposes a high-efficiency power generation system with CO2 capture using cascading coal gasification coupled with chemical recuperation. The proposed system involves using waste heat from the gas turbine exhaust to start coal pyrolysis, achieving the first stage of chemical recuperative pyrolysis. Pyrolysis products, excluding coal gas (CG), are fed into the gasifier for the second stage of coal gasification. Furthermore, the sensible heat of syngas at the gasifier outlet is sequentially used to preheat the gasification agent and tar, supply heat for CG reforming, and generate steam. The cascading coal gasification and stepwise utilization of thermal energy decrease oxygen consumption during gasification and reduce the proportion of partially oxidized coal. The results indicate that, at a 90% carbon capture rate, the net power generation efficiencies of the proposed and reference systems are 40.26 and 37.58%, with exergy efficiencies of 39.22 and 36.55%, respectively. The improvements in the proposed system primarily stem from its highly efficient coal utilization, which decreased exergy destruction for the gasification process by 43%. These results imply the system may enhance efficient, low-carbon coal use.