Exergetic, Thermal, and Fuel Savings Analyses of a Heat-matched, Bagasse-based Cogeneration Plant in Sugar Industries

Abstract

The sugar industry employs different cogeneration schemes to sat-isfy process steam demand, and generates surplus power by upgradingthe steam inlet parameters. A wide range of steam inlet parameters isused in Indian sugar industries, and varies from 21 bar to 110 bar inpressure and 330°C to 540°C in temperature. Most of the people under-stand that higher pressure (HP) steam inlet conditions result in moreefficient power plant. In this article, exergy methods, in addition tomore conventional energy analysis, are employed to evaluate overall andcomponent efficiencies and to identify and assess thermodynamic losses.The analysis is carried out for a heat-matched bagasse-based cogenera-tion plant of a typical 2500 tcd sugar factory using a backpressure steamturbine and an extraction condensing steam turbine for a wide rangeof steam inlet conditions; selected around the sugar industry’s exportcogeneration plant for better choice of cogeneration plant configura-tion. The results indicate that a backpressure turbine plant achieves thehighest energy and exergetic efficiency, and fuel savings; the condensingturbine plant generates maximum power per tonne of cane processed.Steam inlet conditions of 61 bar and 475°C can be considered as theoptimal steam parameters that yield the best thermodynamic advantage.Exergy analysis of the components indicates that the turbine is the mostefficient and the boiler is the least efficient component of the plant.