Back pressure turbine

Cogeneration, the combined generation of heat and power, is an efficient method to reduce cost or to save energy and hence, reduces the pollution. A large number of thermal process industries have this option to install cogeneration system and sugar mill is one of them. In this work, energy and exergy analysis of a sugar mill running on cogeneration system, having back pressure turbine system, has been carried out. Based on the operational data received from the industry, the detailed analysis of the system has been performed. It was found that the output power and excess power of the plant increases with increase in the boiler pressure and therefore, increases the cogeneration efficiency. Also, it was noticed that when the back pressure increases, the turbine output and cogeneration efficiency decrease and, Heat to Power Ratio (HPR) spans over a range of 2.79 to 4.07. From the exergy analysis of the plant, it is observed that the boiler is the main component for exergy destruction. The energy analysis of bagasse fired boiler was carried out and the results showed that energy efficiency was high up to 84.5%. However, the second law efficiency gave 28.5% and irreversibility rate associated with the combustion chamber was 62.19 MW which accounts 55.09% of the total fuel exergy.