MAINTAINING DECLARED PERFORMANCE IN GAS TURBINES DURING INCREASED AMBIENT TEMPERATURES

Abstract

The classical gas turbine process is characterised by air compression from its surroundings, heating fuel in the combustion chambers, hence causing the created flue gases to expand in the turbine and thus induce mechanical action. The performance of gas turbine depends on anything that affects the airflow density and/or mass at the compressor inlet. The most obvious changes in gas turbine performance is a reduction in power and an increase in specific fuel consumption following an increase in the ambient temperature, resulting in significant deviations of the guaranteed (and achieved) values at ISO conditions. In cooling air at the compressor inlet at increased ambient temperatures, an increase in the mass flow and compression ratio is achieved, thus preventing a reduction in power and an increase in specific fuel consumption. When using gas turbines in combined cycle cogeneration power plants for the production of electrical and thermal power, increasing mass flow through gas turbines leads to an increase in power transferred by the flue gases to the turbine exhaust, and which in the waste heat recovery boiler at the combined cycle plant transfers to the steam turbine cycle. Consequently, the effect at the combined cycle plant is a more significant reduction in specific fuel consumption. The work has used the example of the GE-PG610FA turbine to show the dependency on surrounding climatic conditions, and the manner in which this dependency can be reduced or removed.