Exergy analysis of a grid-connected bagasse-based cogeneration plant of sugar factory and exhaust heat utilization for running a cold storage

Abstract

In this study, energy and exergy analysis of a 16 MW cogeneration plant of a sugar factory located in India is carried out. Bagasse leaving the mills with 50% moisture is fed directly into the boiler as fuel. Maximum energy loss (23.021%) as well as maximum exergy destruction (68.219%) is found in the boiler furnace. The fuel moisture alone accounts for 11.89% energy loss due to the absorption of huge portion of combustion heat for its vapourization. Therefore, the effect of reducing bagasse moisture content on this analysis is examined through computer simulation. Reducing moisture content of bagasse from 50% to nil would increase the power output, the cogeneration energy efficiency and the cogeneration exergy efficiency by 3597 kW, 3.66% and 3.02% respectively. It is also found that 6.342% of fuel energy is lost through the exhaust gases. To utilize a portion of this waste heat, a vapour absorption refrigeration system is integrated with the considered plant. It is found that the proposed cooling system would produce a refrigerating effect of 594.714 TR with a COP of 0.721 and can, therefore, be used for preserving large quantities of vegetables in a cold storage.