System design and thermo-economic analysis of a new coal power generation system based on supercritical water gasification with full CO2 capture

Abstract

To achieve sustainable energy supply and carbon neutral, it is essential to enhance the efficiency and reduce carbon emissions for coal power. In this study, a coal power generation system based on supercritical water gasification (SCWG) with full CO2 capture is proposed. The system achieves autothermal gasification by partial oxidation of coal in the SCWG gasifier. Gasification water is preheated by turbine exhaust, and organic Rankine cycle (ORC) is integrated to recover the waste heat of turbine exhaust. Simulation and thermodynamic analysis models of the system are developed. Results show the energy efficiency and exergy efficiency of system with benchmark parameters reach 52.95 % and 54.11 %, respectively. The largest exergy destruction occurs in gasifier and accounts for 41.36 % of the total exergy loss. Irreversibility of heat transfer mainly occurs in water heat exchanger and ORC, accounting for 4.81 % and 5.59 % of the total loss. Effects of key operating parameters on the system performance are investigated. Results show the optimal turbine exhaust pressure is 0.1 MPa, and higher turbine inlet temperature can enhance the system efficiency. System with reheat configuration shows potential in thermodynamic and economic aspects, and the exergy efficiency of double reheat system is improved from 37.25 % to 45.08 %.