Turbine Inlet Air Cooling
Combustion turbine power output can be increased significantly (up to 20%) during periods of warm ambient temperatures by cooling the turbine inlet air down to 45 to 50F (7 to 10C). This technique, called Turbine Inlet Air Cooling (TIAC) can be accomplished very effectively by using mechanical refrigeration with cooling coils installed in the turbine inlet ductwork. This method of using mechanical refrigeration and cooling coils is not limited in its ability to augment turbine power output on days when the relative humidity is high, compared to TIAC systems using direct evaporative cooling (i.e. fogging, or evaporative media) which lose effectiveness as relative humidity increases. Colmac has developed the unique ability to accurately predict cooling coil performance for the very large air temperature and humidity changes seen in these systems. Colmac can supply TIAC coils suitable for operation with a wide range of working fluids including; chilled water, glycols, or pumped (volatile) ammonia. Materials of construction suitable for any ambient operating condition are available. Stainless steel coil casings are offered as standard. with optional integral mist eliminators and drainpans. Standard duty coil construction is copper tubes with aluminum fins for chilled water or glycol, or stainless steel tubes with aluminum fins for pumped ammonia. For offshore and shore-based marine duty installations, Colmac offers a unique conversion coated aluminum fin construction. Conversion coatings offer superior salt-spray corrosion resistance without the possibility of cracking, peeling, or flaking found with many of the dipped and baked coatings. TIAC systems utilizing pumped ammonia evaporator coils is an area of special expertise for Colmac, the company having supplied several large ammonia-based TIAC systems in the USA. Colmac can supply inlet cooling coils for both "green field" and retrofit TIAC installations.
OEM and retrofit coils for cooling generator windings are available from Colmac. Cooling coils for hydrogen-cooled generators utilizing glycol or chilled water with machined casings and bolted removable headers.
Combustion Air Preheating
For fuel-fired industrial heating processes, one way to improve efficiency and productivity is to preheat the combustion air going to the burners. The source of this heat energy is the exhaust gas stream, which leaves the process at elevated temperatures. A heat exchanger, placed in the exhaust stack or ductwork, can extract a large portion of the thermal energy in the flue gases and transfer it to the incoming combustion air. Recycling heat this way will reduce the amount of the purchased fuel needed by the furnace. Coils for combustion air preheating suitable for combustion turbines and boilers are available from Colmac in a variety of materials and configurations.