Effect of pinch point on the performance of a combined cycle gas turbine under Kaduna climatic conditions

In this paper, an analysis was carried out to investigate the effect of pinch point on the performance of a combine cycle gas turbine engine, known as the GE MS9001E combined cycle gas turbine engine. The GE MS9001E is a heavy duty combine cycle gas turbine engine which is currently in use in the Olorunsogo power station in Oyo state, Nigeria. This simulation analysis was performed under the prevailing ambient temperature conditions of Kaduna state. The data for the 2017 ambient temperature conditions of Kaduna state was acquired from NIMET, and from these data the monthly mean ambient temperature values were calculated. These monthly mean temperature values will serve as the basis for the simulation analysis. The simulation comprises of two stages; the first stage involves simulating the performance of the gas turbine engine with GasTurb 11 software while the second stage involves simulating the performance of the steam turbine engine using Aspen HYSYS version 11 software. A detailed procedure was described in chapter three while the simulation results are presented in chapter four. From the results, it showed that at ISO conditions, the power output for GE MS9001E single cycle system is 126.1 MW while for a combine cycle system is 193.2 MW. This implies that the gas turbine produces about 126.1 MW which is about 65.3 % of the combined power output, while the steam turbine produces about 67.1 MW which is about 34.7 % of the combined power output. Varying pinch point values of 0, 5, 10, 15, 20, 25, 30 and 35 were used to carry out this analysis and the results clearly showed that as the pinch point values increases, the turbine power output will decrease and as the pinch point values decreases, the turbine power output will increase. These observations were the same for all the months in the year 2017. The relationship between the pinch point value and the turbine power output can be said to be inversely proportional to one another.