CONCEPT OF MODERNIZATION OF THE OF THE K-300 SERIES STEAM TURBINE FLOW PART FOR TRANSITION TO SUPERCRITICAL STEAM PARAMETERS

The article shows a concept for the modernization of thermal power plant units in Ukraine, to operate with supercritical initial steam parameters, which will significantly increase the specific power and efficiency of steam turbines. As the example of modernization authors used the K-300 series steam turbine flow part, The paper presents a new flow part of the high-pressure cylinder (HPC) and the additional medium-pressure cylinder (AMPC), designed to operate with supercritical parameters. This approach allowed the existing medium and low-pressure cylinders to be left unchanged. The design and calculations of an axial turbine flow part are carried out according to the algorithm implemented in the IPMFlow software package using methods and models of various levels of complexity, from one-dimensional methods for selecting the main characteristics of the turbine stage, methods for analytical profiling of axial stages, to the methods for calculating three-dimensional viscous flows in the turbine flow parts. The main turbine parameters, such as pressure and temperature at the inlet to the HPC, temperature of the intermediate super-heat, temperature and mass flow rate at the outlet from the LPC, were selected. The turbine is designed to operate with initial parameters of fresh steam at a pressure of 30 MPa and a temperature of 650°C with intermediate steam superheating to 650°C. The results of gas-dynamic calculation of the developed HPC and AMPC flow parts are presented. The developed flow parts high efficiency has been confirmed: the efficiency of the HPC flow part is 94.3%, and of the AMPC is 95.1%. It was found that the turbine modernization using supercritical steam parameters allows to increase its power by 65.3 MW and increase the overall thermal efficiency of the plant by 5.9%. The above approach can be used for other turbines during the modernization and rehabilitation of coal-fired TPP units in Ukraine, in particular with a capacity of 200 MW.