Steam Turbines for Cogeneration Power Plants

Steam turbines for cogeneration plants may carry a combination of industrial, space heating, cooling and domestic hot water loads. These loads are hourly, weekly, and seasonally irregular and require turbines of special design to meet the load duration curve, while generating electric power. Design features and performance characteristics of one of the largest cogeneration turbine units for combined electric generation and district heat supply are presented. Different modes of operation of the cogeneration turbine under variable load conditions are discussed in conjunction with a heat load duration curve for urban heat supply. Problems associated with the retrofitting of existing condensing type turbines for cogeneration applications are identified.