Energy and cogeneration targeting for a sugar factory

The sugar industry in India has a potential of 3500 MW to export to the grid. In this paper an energy balance has been carried out for an actual 5000 TCD plant and a Sankey diagram is drawn. A pinch analysis is done for the sugar factory and reveals that the minimum hot utility requirement is lower than the actual by 9%. Modified evaporator designs are proposed as it has been found that the existing plant is not optimum with regard to the surface area of the evaporators and the amount of steam being consumed. Exergy analysis is applied to the existing and the proposed evaporator effects and the results are compared. It is concluded that the amount of steam consumption will reduce by 9 T/h and exergy losses are reduced by 48% of its original value if the existing quadruple effect is modified to a quintuple effect. The turbine hardware model is used to predict the optimum amount of power that can be cogenerated from the system for different generation temperatures at a pressure of 45 bar. The optimum superheat temperature is found to be 600 °C for a backpressure turbine with single extraction. A cost analysis is performed to determine the variation of the average cost of generation of power with the generation temperature of the steam.