Optimising energy efficiency for cogeneration

This paper sets out to find the optimum layout and components of a sugar factory in order to maximise income from the sale of electricity. To reach this objective, a mathematical model of the energy balance has been constructed which is divided into the following parts: input energy in the form of cane bagasse, energy transformed in the boilers, energy used to drive equipment, process energy required and energy converted into electricity. From the mathematical model different alternatives are examined in each area in order to minimise energy consumption and so obtain the maximum possible excess energy to be transformed into saleable electricity. Any drop in energy consumption achieved by an increase in the efficiency of the plant implies a financial outlay which can spiral if efficiency is to be improved further. On a more positive note, however, changing old machinery with high maintenance costs for more efficient, new equipment offsets the initial high investment. The model developed finds the optimum efficiency point in the plant combined with a suitable structure fur replacement of existing equipment which maximises the net value of the projected sale of electricity. After an explanation of the mathematical process involved, the results are given by means of an applications software package which quickly solves the problem of energy optimisation.