Bench studies of the influence of operating conditions on operational safety of steam turbine air-cooled condensers at subzero outdoor temperatures

Condensation processes are widely spread in various branches of industrial production and, in particular, in electric power industry, where, according to experts' data, heat removal in thermodynamic cycles of steam turbine plants (STP) operating as part of combined cycle plants (CCP) and autonomously, in the 21st century will be exercised mainly in air-cooled condensers (ACC). At the same time, the use of ACC as a part of steam turbine units operating in climatic conditions typical for the Russian Federation (RF) determines the relevance of problems to be solved to ensure their safe operation at subzero outside temperatures. One of these challenges is to ensure long-term safe operation of the ACC, with the formation of ice on the inner surface of the heat exchange pipes minimized. To conduct the research, Steam Turbine Air-Cooled Condenser research and training stand was used. The paper presents the combined circuit and measurement diagram of the research and training stand, and gives a brief description of the design of the ACC. Experimental modes have been determined, and methods for processing experimental data and analyzing the results obtained have been developed. As part of the study, experiments were carried out on 18 steady-state operation modes of the stand. At the same time, the values of the main operational parameters of the ACС varied within the following limits: the temperature of the cooling air at the ACС inlet — from minus 11,5°C to minus 1,8°C; the cooling ratio — from 176 to 790. The relative weight content of air in the vapor varied from 0,051% to 0,12%. An analysis of the obtained results was carried out, on the basis of which a relationship was established that allows, for various negative temperatures of the cooling air at the inlet to the ACС, to determine the highest value of the cooling ratio at which its long-term safe operation is possible. An algorithm for using the obtained relationship is given.

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