Thermodynamic predictions of performance of a bagasse integrated gasification combined cycle under quasi-equilibrium conditions

• An investigation on the exergetic feasibility of a BIGCC.
• A survey about the influence of process parameters on system performance.
• Use of exergy composite curves to define the saving potentialities.

The objective of this study was to develop a comprehensive mathematical model of bagasse gasification integrated with a gas turbine combined cycle (BIGCC). The model uses a quasi-equilibrium approach to evaluate the thermodynamic performance of the plant, considering both first and the second law of thermodynamics. The influence of pressure ratio in the compressor (1:4 < rp < 1:10) and of the gas turbine inlet temperature (1000 K < TiT < 1400 K) on system efficiencies is explored. The exergy destruction, losses and recovery in the heat exchanger network are analyzed using pinch methodology. A 46.5% exergy saving by recovering heat in the steam cycle and drying stage can be achieved. Best results are obtained when the turbine inlet temperature is 1323 K and for a 1:10 cycle compression ratio: under these conditions the total exergy efficiency is 32.3% and 35.4% energy efficiency. The atmospheric pressure gasifier was operated at 72% hot gas efficiency and 1073 K. Major exergy destruction occur in the gasifier, dryer and heat exchanger network with a combined 94% of total losses.