AT/UAT Cooling Tower
Induced draft axial fan counterflow cooling tower. The AT/UAT design combines low energy consuming axial fans with high performance counterflow heat exchange. Applicable for airconditioning and industrial cooling.
The AT (Advanced Technology) is executed as per standard with Z-725 (725 g/m² zinc) galvanized steel panels.
The UAT (Ultra-AT) is executed as per standard in AISI 304L stainless steel.
The AT/UAT cooling tower range is CTI (Cooling Technology Institute) certified in the USA and is complient with the International Building Code (IBC) . Evapco Europe provides with each cooling tower a Thermal Performance Guarantee. AT/UAT-units are constructed of 1 to 4 cells with a maximum nominal capacity of 18 MW.
The cooling tower fill material is PVC (polyvinyl chloride) with crossfluted design for optimum heat transfer, strength and stability. The fill is resistant to rot, decay, or biological attack. The fill is able to withstand a water temperature of 55ºC.
In the AT-range, long-lasting corrosion protection is guaranteed with the Z-725 heavy gauge mill hot-dip galvanized steel (Z-725 = 725 g/m² zinc) casing. The galvanized steel construction withstands the most difficult environmental and operating conditions. For special applications, Evapco can produce the AT-units with a stainless steel sump or with a water touched stainless steel construction (both AISI 304 and 316 are possible).
In the UAT-range, the application of stainless steel construction material guarantees durable corrosion protection. The Ultra-AT stands-up against the most severe environmental conditions and water qualities. Full stainless steel or basin in AISI 316L execution is an option.
- Unit: Open cooling tower
- Models: 455 Models ( Type AT/UAT 14-64 till AT/UAT 428-952 )
- Width: 1.226 / 1.826 / 2.283 / 2.578 / 2.991 / 3.607 / 4.248 / 4.696 / 4.905 / 6.112 / 7.344 / 8.626 mm
- Design: Induced draft
- Capacity: 140 kW till 22.128 kW
- Air Flow: 4,4 till 469,9 m³/s
- Fan: Axial
- Drive: Powerband-belt driven
- Low energy consumption
- Low sound emission
- Easy maintenance
- Best choice to avoid Legionaires Disease
- Low risk for recirculation
Low energy consumption
The energy consumption of the AT cooling tower is minimized due to the optimal heat exchange and the application of axial fans. The heat exchange efficiency of counterflow cooling towers is the highest achievable compared to cross-flow and parallel flow heat exchange. On top of the efficiency advantage, it is generally known that axial fans consume on average more than 50% less motor-power than centrifugal fans. The result is an overall optimized and low engergy consumption.
Low sound emission
The standard wide blade aluminum fan is selected and optimized for high efficient cooling tower operations. In additional to the standard fans, aluminum LOW SOUND FANS and FRP SUPER LOW SOUND FANS can be installed. Together with water silencers in the sump, sound reductions up till 15 dB(A) can be established.
The AT-design is optimized for easy access to all critical locations and components. The inlet louvers are removable and provide an easy access to the sump. The complete sump can be cleaned from the outside of the unit. Large access doors provide easy access to the eliminators, spray- and drive system for maintenance purpose. The fill can be accessed both from the top access door or via the sump, additional fill access doors can be foreseen as an option.
Best choice to avoid Legionaires Disease
Maintenance is crucial to avoid the proliferation of the LD-bacteria. Avoidance of the penetration of sunlight to the inner part of the cooling tower, no stagnant zones in the sump and cleanable spray systems are of equal importance. The AT cooling tower is equipped with WST (Water and Sight Tight) inlet louvers to avoid the penetration of sunlight into the sump via the inlet louvers. The high performance drift eliminators (0.001% drift rate) avoid the penetration of sunlight via the fan-opening onto the spray system and fill. The sump is sloped and drains completely, stagnant zones are not present. The spray system is completely dismountable (including nozzles) and is executed with a removable end-cap for easy cleaning.
Low risk for recirculation
Due to the large distance between the high speed air outlet and the multi-sided low speed air inlet, the risk for recirculation is minimized.
Warm water from the heat source is pumped to the water distribution system at the top of the tower. The water is distributed over the wet deck fill by means of large orifice nozzles. Simultaneously, air is drawn in through the air inlet louvers at the base of the tower and travels upward through the wet deck fill opposite the water flow. A small portion of the water is evaporated which removes the heat from the remaining water. The warm moist air is drawn to the top of the cooling tower by the fan and discharged to the atmosphere. The cooled water drains to the basin at the bottom of the tower and is returned to the heat source. The vertical air discharge and the distance between the discharge air and fresh air intakes, reduces the chance of air recirculation, since the warm humid air is directed up and away from the unit. For detailed layout information please consult EVAPCO’s Equipment Layout Guidelines Bulletin 311.
1. Casing and basin design
High Performance drift eliminators
The drift eliminators remove entrained water droplets from the air stream to limit the drift rate to less than 0.001% of the recirculating water rate. The unit can be located in areas where minimum water carryover is critical. The drift eliminators are constructed of an inert polyvinyl chloride (PVC) plastic material which effectively eliminates corrosion of these vital components. They are assembled in sections to facilitate easy removal for inspection of the water distribution system.
Water and Sight Tight air inlet louver (WST)
The air inlet louvers are both water and sight tight to ensure that the water stays in and sunlight stays out of the cold water basin. The water tight design maximizes thermal performance while minimizing water loss. The sight tight design inhibits algae growth more effectively than previous designs.
Z-725 Galvanized steel panels (AT only)
EVAPCO has developed the ultimate system for corrosion protection in galvanized steel construction - the EVAPCOAT Corrosion Protection System. Z-725 is the heaviest level of galvanizing available for manufacturing evaporative condensers and has a minimum of 250 % more zinc protection than competitive designs using Z-275 steel.
2. Heat transfer system
EVAPCO’s patented EVAPAK® fill is specially designed to induce highly turbulent mixing of the air and water for superior heat transfer. The fill sheets are thermally formed into a cross flute design. The individual fill sheets are bonded together to form rigid fill blocks. The fill blocks are then stacked within the unit’s protective casing. The structural strength of the assembled fill pack enables it to be used as a working platform. EVAPCO fill is impervious to rot and decay.
3. Mechanical design
Power-Band Drive System
The AT Cooling Tower features the highly successful, easy maintenance, heavy duty Power Band Drive System. It consists of Standard heavy-duty pillow block bearings with a minimum L10 life of 75,000 hours, extended lube lines, external motor/belt adjustment, aluminum alloy sheaves, solid-back multi-groove Power- Band belts and totally enclosed motors.
Single speed fan motor
Each Evapco unit is equipped as per standard with a heavy duty, single speed IP55 TEFC / TEAO electrical motor.
Standard axial fan
The standard fans are heavy duty statically balanced axial propeller type. The fans are constructed of extruded aluminum alloy blades, installed in a closely fitted cowl with venturi air inlet for maximum fan efficiency. Each fan blade is individually adjustable. The fan cowl is covered with a heavy gauge hot dip galvanized wire fan guard.
4. Water distribution
EvapJet’s unique design ensures that every square meter of heat transfer surface receives complete and even water coverage, resulting in maximum thermal performance. The EvapJet nozzle is constructed of precision molded ABS, giving the nozzle superior corrosion resistance.
Spray-water distribution system
The water distribution system is enclosed and completely protected by the casing panels and drift eliminators. The water distribution system is made with non-corrosive materials including schedule 40 PVC pipe and durable ABS plastic nozzles. The spray branch piping is easily removed and designed with threaded end-caps for easy cleaning. Evapco’s design avoids the problems of biological growth and clogging.
5. Maintenance and inspection
Large access door
A large hinged access door is located on the side of the unit for easy access to the fan drive system. The belt can be adjusted by tightening the tensioning-bolts on the motor base and the tension can be checked easily through the access door, all while standing at the side of the unit. The bearings can also be lubricated from the side of the unit. The bearing lubrication lines have been extended to the exterior casing and are located by the access door.
6. Operational control
Mechanical water level control
Simple but reliable water level control system with adjustable mechanical float and brass float-valve.
The Big AT
EVAPCO continues its dedication to advancements in induced draft, counterflow cooling tower technology and easy maintenance by expanding the AT product line. Now the AT line has a model for every application!
- CTI Certified
- IBC Compliant
- 4.444 to 22.128 kW
- 1, 2, 3 or 4 cell arrangements
- Cells with a 4,248 x 7,845 mm footprint
- The same features and options as the 'small' AT