Gas turbines are generally rated to operate at 100% efficiency at 15°C. Any increase in ambient temperature above this will reduce the turbine efficiency. At 30°C for example, there will be approximately a 10% reduction in efficiency.

The Baltec OptiMist Fogging System is an inexpensive way to reverse these losses, and can be easily retrofitted to existing turbine installations. The only requirements are a supply of demineralised water and 3-phase electrical power. Typical payback time for an OptiMist system is around 12 months.

The OptiMist system is fitted upstream of the turbine compressor and cools the inlet air by spraying an extremely fine mist of water into the duct, which immediately evaporates, thus cooling the air. The pumps and control system are are mounted on a skid at ground level, normally adjacent the turbine, whilst the high pressure spray manifolds and nozzles are fitted inside the inlet ductwork. To fit the system to an existing installation, a turbine downtime of only 1-2 days is all that is required.

Each OptiMist system is custom designed based upon the average climatic conditions at site. In operation, the optimal level of cooling (ie. water flow rate to the nozzles) is constantly calculated and adjusted by the OptiMist control system, based upon the current ambient conditions.

An additional larger pump is normally supplied with the OptiMist system to provide overspray, where further water is sprayed into the inlet air, in addition to the amount required to achieve 100% saturation. Further gains of up to 5% may be achieved through the use of overspray.

As well as the OptiMist Fogging System, Baltec can also provide more traditional inlet cooling systems. The downside of these systems is that they cannot easily be incorporated into an existing design, and are really only suitable for new Filterhouses.

Evaporative Cooling works by passing the turbine inlet air through a stage of evaporative media. The media is kept wet at all times by pumping water up from a storage tank at ground level. The air is cooled as it passes through the media by water evaporating from the media surface.

Chillers work on the same principle as refrigerators, passing the inlet air past a set of heat-exchanger pipes which are kept cold by a refrigerant gas that is pumped through them. Heat is extracted from the gas at the skid by a radiator before it is circulated again.