An efficient methanol pre-reforming gas turbine combined cycle with mid-temperature energy upgradation: Thermodynamic and economic analysis

Abstract

A novel design has been developed to optimize the performance of the gas turbine combined cycle (GTCC) plant by integration with a methanol steam reforming (MSR) system based on the principle of the cascade utilization of chemical energy. In the integrated MSR-GTCC system, the methanol fuel releases its chemical energy through two successive processes: the thermal reforming reaction of primary fuel in the MSR, and the combustion reaction of reformate syngas in GTCC. The energy required for the endothermic MSR is provided by a portion of mid-temperature heat (MTH), which is extracted from the bottoming cycle of GTCC. By such incorporation, the loss in the conversion from chemical energy to physical energy is reduced and the power generation capability of MTH is improved effectively. Based on a 530 MW GTCC plant, the thermodynamic analysis reveals that the energy and exergy efficiencies are promoted by 7.3 % and 7.2 %, respectively. Besides, the profit of the integrated design is 193.9 M$ higher than that of the conventional system over the lifespan. Furthermore, sensitivity evaluation indicates that the non-reflux MSR process is suitable when the reaction temperature exceeds 250 °C and the optimal water-to-methanol ratio is approximately 1.0 for the integrated MSR-GTCC system.