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 satisfy process steam demand, and generates surplus power by upgrading the steam inlet parameters. A wide range of steam inlet parameters is used in Indian sugar industries, and varies from 21 bar to 110 bar in pressure and 330°C to 540°C in temperature. Most of the people understand that higher pressure (HP) steam inlet conditions result in more efficient power plant. In this article, exergy methods, in addition to more conventional energy analysis, are employed to evaluate overall and component efficiencies and to identify and assess thermodynamic losses. The analysis is carried out for a heat-matched bagasse-based cogeneration plant of a typical 2500 tcd sugar factory using a backpressure steam turbine and an extraction condensing steam turbine for a wide range of steam inlet conditions; selected around the sugar industry's export cogeneration plant for better choice of cogeneration plant configuration. The results indicate that a backpressure turbine plant achieves the highest energy and exergetic efficiency, and fuel savings; the condensing turbine plant generates maximum power per tonne of cane processed. Steam inlet conditions of 61 bar and 475°C can be considered as the optimal steam parameters that yield the best thermodynamic advantage. Exergy analysis of the components indicates that the turbine is the most efficient and the boiler is the least efficient component of the plant.

Efficiency Improvement in Sugar Mills; The Role of High-Pressure Boiler Technology in Cogeneration

“…Steam production is directly proportional to the boiler pressure, and the higher the pressure, the greater the steam production. Moreover, boosting the steam pressure and temperature of CEST can further increase electricity generation [7]. In contrast, low-pressure boilers have been used in sugarcane mills for many years.…”