An analysis of the effect of gas turbine compressor air preheating on the technical and economic indicators of a PGU-450 unit

Abstract

We study the effect of preheating the air entering a gas turbine compressor using a standard closed air heating circuit system with heat supply from the heat network of the Urengoy city district power plant on the efficiency of a PGU-450 unit and this power plant as a whole. An analysis was conducted to compare the data obtained as a result of assessing the existing plant characteristics of GTE-160 gas turbines (SGT5-2000E), the adopted operating modes of air heating systems (closed air heating circuit and anti-icing system) and the effect of the operation of these systems on the specific fuel consumption of a PGU-450 unit and the Urengoy city district power plant according to the daily calculated technical and economic parameters of the power unit operation. As a result of full-scale tests carried out with the air heating system at the nominal load of a PGU-450 power unit, the optimal temperature was established to be +6.4°C. During the air heating from -5.0°C to +6.4°C, the specific consumption of the conventional fuel per 1 kWh of electricity decreased by 1.4 g. The reduced specific consumption of the conventional fuel for the supply of electric energy at an increase in the extraction ratio comprised 2.43 and 2.35 g for the equipment of the backup thermal power station and the power plant as a whole, respectively. Thus, the use of a closed air heating circuit with the unutilized network water heating leads to a positive thermal efficiency effect. The preheating of the air entering the gas turbine compressor leads to an increase in its efficiency by 0.3%. A further increase in excess of the optimum temperature leads to a decrease in the available capacity of the combined cycle plant by 3.1 MW per each degree.