Study of the possibilities of using natural gas for cooling various coolant flows at combined heat and power plant

Abstract

The article discusses the application of two technologies for cooling different coolant flows at the CHP and makes a comparative assessment of their impact on the energy efficiency of the turbine plant. The first technology consists in cooling the feed water flow of the heating system, and the second technology is implemented by cooling the additional feed water of boilers. The technology of cooling the make-up water of the heating system provides for introducing a heat exchanger that would cool the make-up water before mixing it with the water of the heating system. The technology of cooling the additional feed water of boilers is implemented by introducing a heat exchanger downstream the deaerator, before feeding the water into the main condensate path. In both cases, in the heat exchanger, the cooling medium is natural gas supplied to the burners of boilers, and the heating medium is make-up or additional feed water. A comparative calculation of the energy efficiency indicators of technologies is performed using the method of specific electricity generation based on thermal consumption. During the calculations, the data obtained at an operating CHP plant and the temperature schedule of a heating network for the 2021 – 2022 heating season were used. Calculations were performed for a thermal power plant with a T-100-130 turbine. For the most accurate comparison of the effectiveness of the technologies under consideration, the source data were taken as close as possible, and the value of the make-up water and additional feed water consumption correspond to each other — for this reason, the heating season period was considered. The outdoor temperature values for the specified period were taken from the weather archive of a weather station. Comparative results of calculations of the efficiency indicators of the use of these technologies are presented, expressed in additional heating generation of electricity, in the economy of conventional fuel and in monetary terms over the heating period.