Cogeneration potential of an operating diesel engine power plant
Moses Jeremiah Barasa Kabeyi, Oludolapo Akanni Olanrewaju
Abstract
Waste heat recovery systems convert the thermal energy in waste fluid streams into useful work. Diesel engine cogeneration systems are waste recovery systems using technologies and devices with main elements being the diesel engine prime movers, the electric generator, Rankine cycle steam turbine, exhaust heat recovery boiler super heaters, and control and instrumentation devices. Diesel engines exhaust significant recoverable heat energy that can be converted to extra electricity using a Rankine cycle plant. In this study, the cogeneration potential of an operating diesel engine power plant was established. The cogeneration potential of a 119.7 MW operating power plant in Kenya is established. The study showed that subject to limits imposed by presence of sulphur in fuel and hence existence of sulphur dioxide in the exhaust, each engine of capacity 17.1 MWe has recoverable thermal energy of about 1.33 MWth while the whole plant with seven engines is about 9.3 MWth for the 7 engines at plant optimum loading conditions which can generate 8.5 MWe extra electricity under optimum conditions. The study recommends the development of up to 9 MWe Rankine cycle steam turbine-based cogeneration power plant. Diesel power plant cogeneration is a technically and economically viable strategy to increase the generation efficiency of diesel power plants and reduce the pollution intensity and financial performance of the diesel power plant leading to reduction in cost of power and higher return on investment for investors.