A novel combustion turbine inlet air cooling system

Combustion turbine performance is known to significantly deteriorate at elevated ambient temperatures in the Gulf Countries. This phenomenon is typically tackled by incorporating turbine inlet air-cooling systems that are generally classified under evaporative and refrigerative types. Evaporative systems have limited improvement on the turbine performance and add risk of water carryover into the compressor. However, they are simple, require minor modifications to the inlet house, and have low capital and operating costs. On the contrary, refrigerative systems are complex and require high capital and operating costs and also consume significant parasitic power for the water chillers. Nevertheless refrigerative systems guarantee the required inlet air temperature irrespective of the ambient conditions thus, achieve higher power augmentation. This paper introduces a novel system that combines the advantages of both the above technologies. The system basically consists of chiller, cooling tower, inlet air coil, interconnecting piping and controls. The tower works as a primary source of cooling to its maximum capability after which the chiller intervenes to supplement it as a secondary source in order to achieve the desired inlet air temperature that tower solely can not achieve it. The system components are arranged in a manner such that the chiller system alternates between two distinct operational configurations to suit the incurring ambient condition; one is similar to a classical chilled water system while the other is a new arrangement in which cooling is attained by the tower solely or assisted by the chiller. The system guarantees significant increase in power output, reduction of heat rate and exhaust temperature of turbine under various ambient conditions. The system requires smaller chiller that operates less hours and consumes much lower energy than the conventional refrigerative systems. The system also reduces the risks associated with evaporating water into the compressor intake.