Modernisation of turbines at Ukrainian TPPs to operate at super- and ultra-critical initial steam parameters

Purpose

Upgrade steam turbines of 300 MW power units at Ukrainian thermal power plants to operate at super- and ultra-supercritical initial steam parameters to significantly increase their efficiency. The new turbine is expected to increase efficiency to 48-53% with an appropriate level of reliability and to fit within the dimensions of existing turbine rooms and foundations of thermal power plant power units for K-300 series turbines.

Tasks

• development of a constructive scheme of a steam turbine for operation at super- and ultra-supercritical steam parameters;
• three-dimensional shape of high-temperature flow parts of a high and medium pressure cylinder of high efficiency;
• design of the flow part of a high-efficiency steam turbine for operation at super and ultra-supercritical steam parameters with increased efficiency at an appropriate level of reliability, as well as dimensions that allow its location in existing machine rooms and on the foundations of power units of K-300 series turbines.

Description

Today in Ukraine, much of the electricity and heat generation equipment is worn out and inefficient and requires either complete replacement or major modernisation. Obviously, in both cases, the equipment should be upgraded in such a way as to improve its energy efficiency and environmental friendliness.
Both domestic and international experience shows that the most promising area for the development of the thermal power industry is the conversion of power units to operate with increased steam parameters. By increasing the pressure and temperature of the steam generated in the boiler, its internal energy increases, which is converted into the kinetic energy of the electric generator shaft rotation in the turbine. It has been proven that this increases not only the amount of electricity generated, but also the efficiency of the power unit, i.e., an increase in steam parameters allows for more electricity to be generated compared to a power unit with lower steam parameters for the same amount of fuel burned.Of course, it is not possible to simply supply steam with increased parameters to the inlet of an existing turbine designed to operate with one steam parameter. This will lead to the fact that the internal energy of the steam will not be fully utilised, and individual elements of the turbine will not be able to withstand the increased pressures and temperatures over time.
Therefore, the conversion of power units to higher steam parameters requires a significant upgrade of power unit equipment, which cannot be done without innovative approaches. Scientists at the A.M. Pidgorny Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine have developed a conceptual approach to solving the problem of switching powerful TPP power units to operate with so-called supercritical initial steam parameters – pressure and temperature of more than 24.5 MPa and 565 C, respectively. The approach was taken to develop a new turbine and auxiliary equipment not from scratch, but using those turbine elements that have already proven their efficient operation at lower steam parameters. This can be done because as steam passes through the turbine stages, the temperature and pressure gradually decrease and eventually reach the values for which these existing turbines were designed.
In other words, only a part of the turbine’s high pressure section requires significant modernisation. The proposed conceptual approach has been tested on 300 MW series turbines manufactured by JSC Ukrainian Power Machines when they were transferred to supercritical parameters. Based on the results of multivariate technical and economic calculations using modern methods of thermodynamic and exergy analysis, as well as taking into account the real technical capabilities of domestic engineering, it was proved that the optimal steam parameters at the inlet to the new turbine are 30 MPa and 650 °C. Based on these parameters, a thermal scheme was proposed and elaborated in detail, which can be used for the turbine modernisation.

At the same time, the medium and low pressure parts, as well as the regenerative heating system for the feedwater of the existing turbine, are preserved to the maximum extent possible, which will significantly save the costs of developing and re-equipping the manufacturer’s equipment when implementing the proposed conceptual approach in production. The proposed upgrade of 300 MW turbines with a payback period of about 4.5 years will increase the electrical efficiency of the power unit by almost 5.5% and reduce specific CO2 emissions by almost 13% compared to the original power unit.

Fields of prospective use

Power machine engineering

Potential stakeholders

JSC “Ukrainian Power Machines”

Budget

Required: needs to be clarified

Inquired: 0M ₴

Workplace creation potential: needs to be clarified

Possible sources of funding

International funds, funds of interested enterprises (JSC “Power Machines”, utilities)

Website

www.ipmach.kharkov.ua