Analysis and performance evaluation of gas turbine by incorporating a wetted evaporative media cooler

Abstract

Gas turbine shows great inverse effect on ambient air temperature. The efficiency and net power output of the gas turbine increases with decrease in ambient air temperature. Nigeria with an average ambient air temperature of 31°C tends to experience a drop in gas turbine efficiency and net power output. It has been proven that by employing wetted evaporative media cooler to the inlet of the compressor, the gas turbine plant performance can be maximized; this employed devise reduces the inlet temperature. An open cycle gas turbine Frame 9E in Ihovbor power plant Benin Edo State, Nigeria generating electricity at a capacity of 450MW was used as a retrofitted study for the research by using Aspen HYSY V9 simulation one software model. The results, from plots of graphs, when interpreted, depicts a direct proportionality between ambient air temperature and compressor work; an inverse proportionality between ambient air temperature and net power output of the turbine; a direct proportionality between ambient air temperature and specific fuel consumption; an inverse proportionality between ambient air temperature and plant efficiency. The numerical value for the drop in ambient air temperature consequent upon the use of evaporative cooler is 11.25 0 C. Since the gas turbine is a thermal engine, its inlet temperature – ambient temperature – has significant effect on the aforementioned parameters; so that, results from the study, shows; the evaporative cooler results in a drop in ambient temperature of 11.25°C, showing an increase of about 3.7% efficiency and 11.56MW net power output of the turbine. Drop in specific fuel consumption is 0.024kg/KWh. From the research, it is deduced that gas turbine plants perform better in temperate regions than tropical regions. Therefore, to maximize the performance of a gas turbine plants in high temperature climates, retrofitting it with an air cooler will lower the temperature to a value close to the design temperature before compression takes place and it will tend to improve gas turbine performance in tropical country like Nigeria.