EFFICIENCY EVALUATION OF STEAM-GAS PLANTS WITH THE SOLID OXIDE FUEL CELLS INTEGRATION

Abstract

Today in Ukraine the generation of electricity increasing is an extremely urgent task, which can be solved in a short period not only by the creation of new power plants, but by the modernization of high-power steam power units of existing thermal power plants. The conceptual solutions for the use of the gas turbine cycle and solid oxide fuel cell (SOFC) technology as an add-on to existing high-power steam turbines to increase the efficiency and environmental friendliness of their operation was developed. The paper considers the ways of complex modernization on the example of power units of CHPP-5 in Kharkiv with T-110/120-130 steam turbines. As an add-on, it is proposed to use the GTE-60 gas turbine unit with a capacity of 60 MW, produced at the Zorya-Mashproekt State Enterprise, Mykolaiv. Also, the integration into the “T-110/120-130–GTE-60” steam-gas circuit of a modular SOFC unit with internal reforming with a total capacity of 20 MW, which is composed of 40 tubular fuel cells with a capacity of 500 kW is considered. In the study of the condensation mode of the steam turbine operation, the following results were obtained: with the standard scheme of parallel connection of the gas turbine unit to the steam turbine with the supply of steam produced in the heat recovery steam generator (HRSG) to the medium-pressure turbine, the electrical efficiency was 42%, and the total electrical power of the installation was 170 MW; when the gas turbine unit was connected in parallel to the steam turbine with the supply of steam produced in the HRSG to the high-pressure turbine, the electrical efficiency reached 44.75%, and the total electrical power was 170 MW (during the operation of such a scheme, the steam is overheated due to additional combustion of gas in the HRSG); the waste circuit for connecting the gas turbine unit to the steam turbine with SOFC and regeneration substitution provided the electrical efficiency of 46% and the total electrical power of 190 MW; in the scheme of parallel connection of the gas turbine unit and SOFC to the steam turbine with the supply of produced steam to the high-pressure turbine, the electrical efficiency was 49.4% with the total electrical power of 190 MW. A comparative energy analysis of various options for combined circuit solutions for the modernization of the existing power unit of CHPP-5 was performed. This analysis showed that the greatest increase in electrical efficiency by 12% compared to the existing T-100/120-130 steam turbine was achieved in the scheme of parallel connection of the GTE-60 gas turbine unit with gas afterburning in the HRSG and SOFC with a total capacity of 20 MW.