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Steam turbines are the basis of thermal power. Despite their prevalence, they need to be improved with the latest research. At the same time first of all experts should pay attention that the maximum temperature of steam in these installations does not exceed 550 °C because of low corrosion resistance and insufficient durability of tubes of the boiler units working at a high pressure difference (to 25 MPas) inside and outside of tubes. At the same time in modern gas turbine plants the temperature of the working fluid at the entrance to the high pressure turbine is 1400-1500 °C. This is achieved by the fact that the turbine blades, which are made of heat-resistant steel, are able to withstand temperatures significantly exceeding the maximum limit currently set for steam turbines. Turbine blades, moreover, are not subject to such a large pressure difference as the tubes of boiler units. To increase the efficiency of steam turbines, a new method of increasing the steam temperature in front of the turbine has been proposed. It is based on the use of oxygen and natural gas. Increasing the maximum cycle temperature from 540 to 800 °C allows to increase the thermal efficiency by 8.1% and efficiency by 6.4%. An unconventional method of increasing the maximum cycle temperature of the steam turbine unit K-1200-240 to 800 °С is described, which allows to significantly increase its thermal and effective efficiency. The essence of the method is to mix superheated steam coming from the superheater of the boiler with the products of combustion of hydrocarbon fuel in oxygen. This solution avoids the problem of mechanical strength and corrosion resistance of superheater tubes at high temperatures. One of the consequences of the method is to obtain a significant amount of pure carbon dioxide (340 t / day in a plant with a capacity of 1200 MW), which can be disposed of or buried to reduce emissions. [ABSTRACT FROM AUTHOR]

In Ukraine, the design life of the most NPP units has expired. In this regard, it is proposed to extend the life of the NPP by combining it with a gas turbine plant (GTP), namely, the use of a waste heat boiler (WHB) on exhaust gases to produce 20% of the nominal steam consumption. The power of the reactor unit is reduced to 80%, which makes it possible to increase the life time of the reactor by reducing the rate of accumulation of fluence, and the steam turbine will operate at nominal mode. In addition, the gas turbine can be used as a backup power source for the reactor unit. In the schemes of combining steam turbine units (STU) of NPPs with GTP presented in the literature, options for increasing the power of the steam turbine are considered. From the analysis it follows that this always leads to a non-design mode, which is characterized by a decrease in the efficiency of the stages and the turbine as a whole. In the proposed scheme, the STU operates in nominal mode with the design resource and efficiency. The method of calculation of the proposed scheme of combining GTP with NPP is considered in the work and the optimization of the basic parameters (gas compression ratio, temperature of the gas in the WHB, temperature difference in the WHB) in relation to the maximum of the electric efficiency of the GTP and the nuclear power complex (NPK) (ηGTP = 40,79%; ηNPK = 41,19%) is carried out. The scheme with intermediate overheating of the gas in the WHB. As a result, it was determined that the intermediate overheating of the gas allows to increase the efficiency of the gas turbine to 45,44 % (T0 = 1350 ºC, compression ratio 25 and gas temperature at the outlet of the WHB 903 K). The efficiency of the NPK ηNPK = 42,9 %. This mode of operation for 20 years makes it possible to extend the life time of the NPP for 5 years, which is enough for the construction of a new unit. In the autonomous mode, at WHB bypass and air heating in the regenerative heater, ηGTP = 50,87 %. [ABSTRACT FROM AUTHOR]