An Analysis of the Technical and Economic Characteristics of Air Cooled Condensers for Steam Turbines as Part of Combined Cycle Plants

Abstract

The article proposes a procedure for determining the optimal parameters of an air cooled condensing unit (ACCU) for the steam turbine used as part of a combined cycle plant (CCP). The procedure takes into account the effect the number of ACCU sections has on the pressure in the condenser in interconnection with the annual spell of the operation mode considered and the variation in the steam turbine power output and annual supply of electricity. Approximation of the generalized data on the spells of air temperatures for Krasnodar is carried out, and the relative service hours of the steam turbine unit (STU) operation at reduced power output has been determined. The variation of the electricity generation and supply, as well as the CCP power output under the climatic conditions in the south of Russia are analyzed. It is shown that the period of time for which a certain air temperature persists has a significant influence on the annual performance indicators of a steam turbine equipped with an air-cooled condenser. For a combined cycle power unit comprising a GTE-170 gas turbine produced by Power Machines JSC and a 76 MW steam turbine produced by the Ural Turbine Works, the optimal ACCU parameters for its operation under the conditions of Krasnodar have been calculated using the newly developed procedure. It is shown that the optimal number of ACCU sections makes from 18 to 21 pieces. The annual time of STU operation has been calculated and graphically illustrated at its power output N < N_nom and the specified number of ACCU sections. The power performance characteristics for an ACCU containing different numbers of sections (from 12 to 24) have been obtained, including the average values of power output loss \(\Delta {{\bar {N}}_{\sum }}\), additional loss of energy generated \(\Delta {{E}_{{{\text{add}}}}}\), the average value of the loss of electricity generated \(\Delta E\) with taking into account the air temperature spell duration, and the total loss of energy generated \(\Delta {{E}_{\sum }}\). The manner in which changes occur in the power plant economic indicators in decreasing the number of ACCU sections from 24 to 21, 18, and 15 is shown.