Enhancement of Marib Gas Turbine Power Station Using Air Cooling Fogging System

Abstract

Energy crises is one of the major causes for the economic decline in Yemen since large portion of the invested capital is spent on standalone small-scale low efficiency electrical generators. This goes not only for the industrial sector, but also for the simple citizens to provide some of their basic electrical requirements. The establishment of Marib gas turbine (GT) station as the first gas turbine based plant in Yemen in 2009 has slightly reduced the gap between power requirement and consumption. Marib power plant consists of three GT units of 163 MWe nominal net output per unit with additional 400 MWe in the second phase of the project. However, its high potential is wasted by using the simple GT cycle without any enhancement method such as combined or even recuperative cycles. Additional to the high altitude of its location that dropped significantly its efficiency down to 29 %. Thus, around 71 % of the fuel thermal power is discharged to the ambient as a waste. This study investigates one of the enhancement methods for Marib GT plant without any major modification on the current configuration of the station. The study showed that the rise in ambient temperature in summer could cause a power output degradation up to 0.6 % per 1°C. Thus, the addition of fogging inlet air cooling system was found to be one of the simplest and economical solutions. A mathematical model is developed to determine the impact of ambient conditions (i.e. temperature and humidity), on turbine performance. The developed mathematical model is verified with on-site operation data from Marib power plant. The results showed that Marib gas turbine power plants have excellent potential for fog operation with Evaporative Cooling Potential of 11.5 - 24 ºC. The results also showed a significant enhancement in turbine performance after using the fogging system with additional output power boost up to 30 MWe.