Thermodynamic Analysis of Integrated Gasification Combined Cycle Integrated with Organic Rankine Cycle for Waste Heat Utilization

The utilization of waste heat from power plants, which is generally lost to the atmosphere, can reduce energy wastage significantly. Heat recovery systems are necessary for power plants to utilize the waste heat, which improves overall efficiency and reduces the need for additional fossil fuel consumption and its associated carbon emissions. This study uses the organic rankine cycle (ORC) to recover waste heat from the flue gas exhaust of an integrated gasification combined cycle (IGCC) power plant. A detailed thermodynamic analysis is conducted to study the outcomes from a 400 MWe IGCC plant and IGCC integrated with ORC. The IGCC plant is a reconfigured 400 MWe pressurized pulverized combined cycle power plant. The ORC uses R245fa as its working fluid, and high-ash Indian coal is used as a fuel input for the IGCC plant. The modelling and simulation of different plant configurations have been done using the software "Cycle-Tempo". The thermodynamic analysis reveals that the IGCC plant has energy and exergy efficiencies of 45.50% and 41.62%, respectively, and the IGCC-ORC plant has energy and exergy efficiencies of 45.84% and 41.92%, respectively. This study also shows that the combustion chamber and cooling water system in condenser experience maximum exergy and energy losses. Moreover, the ORC produces a net additional power output of 2.34 MWe with energy and exergy efficiencies of 12.48% and 42.54%, respectively. This additional power generation helps in avoiding around 51 tonnes/day of CO2 when similar amount of power is produced from a coal-based thermal power plant.