부산대학교 도서관

This paper describes a method of retrofitting an existing coal-fired generating unit to provide the capability for district heating. The technique involves the extraction of steam from turbine crossovers to heat water and modifications of the feedwater heating system. Backpressure turbine-generators are used to minimize the capacity losses of the unit. Seasonal extraction of steam for district heating is possible while retaining the unit's capability to meet peak electrical load at normal efficiency when there is no heating load. A study was performed to compare the retrofit scheme (e.g. having two backpressure turbines) with an alternate scheme having no backpressure turbine. It is concluded that the proposed concept for retrofitting large steam electric units does not require major turbine modifications, it minimizes electrical capacity losses during district heating operation, and allows the generating unit to operate at its peak capacity when there is no heating load.