Closed Cooling Towers: An Introduction
The closed cooling tower, also referred to as an evaporative air cooler or closed-circuit cooler, is an efficient heat rejection device. Its core principle involves a tubular heat exchanger (coil bundle) housed within a tower structure. Circulating air and spray water interact with the exterior of these tubes, while process fluid circulates in a closed loop inside them. This configuration facilitates effective heat transfer from the internal process fluid to the external environment.
The closed-loop design of the process fluid circuit is a key advantage, preventing contamination, scaling, and fouling. This protects critical connected equipment (such as furnaces, lasers, or power supplies), ensuring efficient operation and extending system lifespan. Furthermore, in cooler ambient conditions, the evaporative spray system can be switched off, transitioning to dry air cooling mode and conserving significant amounts of water. In the context of national energy conservation policies and increasing water scarcity, closed cooling towers have seen widespread adoption across industries including steel metallurgy, power generation, electronics, machining, and HVAC systems.
Closed cooling towers can be categorized based on several design parameters:
By Air/Water Flow Direction:
Counter-flow Closed Cooling Tower
Cross-flow Closed Cooling Tower
Hybrid-flow Closed Cooling Tower
By Casing Material:
Galvanized Steel
Aluminum-Zinc Alloy Sheet
Stainless Steel
Fiber Reinforced Plastic (FRP)
By Heat Exchanger Coil Material:
Copper Tube
Stainless Steel Tube
Carbon Steel Tube
Titanium Tube
Aluminum Tube
By Fan Type:
Induced Draft (Fan on top, pulling air)
Forced Draft (Fan at base, pushing air)
Operational Control Procedures
2.1 Startup and Initial Checks
First, verify all piping and control wiring are properly connected. Press the "Main Pump On" and "Fan On" start buttons (indicator lights will illuminate). Then, perform the following checks:
Pump: Confirm rotation is clockwise, flow direction matches pipe arrows, water pressure is normal, and there are no leaks or abnormal noises.
Fan: Verify airflow is directed upward (exhausting from the top). If airflow is reversed, swap any two of the three power leads to the fan motor in the control cabinet. Check for abnormal vibration or noise.
Immediately address any issues identified. If unresolved, contact technical support.
2.2 Spray System (Automatic Temperature Control)
The spray pump operates via an automatic temperature control system, activating and deactivating based on set temperature points to optimize water usage.
Important: Temperature controller parameters are typically pre-set at the factory. Users should not alter these settings arbitrarily, as incorrect changes may lead to control failure.
If parameter adjustment is necessary, user technicians must carefully review the product manual or consult with our technical personnel before proceeding.
2.3 Normal Shutdown
For standard shutdown, simply press the "Pump Stop" and "Fan Stop" buttons.
Critical Note for Furnace Cooling: When cooling equipment like induction or melting furnaces, the cooling system must not be stopped immediately after the furnace shuts down. It must continue running until the furnace core has completely cooled. Therefore, such systems are often equipped with a time-delay relay.
Procedure: In case of a main furnace power failure, set the time relay to the required cooling duration. Activate the time relay switch and turn off the fan. Upon the next system startup, simply deactivate the time relay switch; the pump will resume operation automatically. This protects the furnace and saves energy.
WARNING: The pump must NEVER be operated without water.
2.4 Resetting Thermal Overload Protection
The electrical system includes thermal overload relays for both the fan and pump motors. If a relay trips, you must press the red reset button located on the bottom of the corresponding relay (below its AC contactor) fully to reset it. Otherwise, the start buttons will be unable to engage the contactors.
2.5 Make-up Water Replenishment
Regularly observe the water level sight glass on the closed cooling tower's basin. If the water level falls below two-thirds of the basin's capacity, promptly add softened water to the specified level.
We are a professional electric furnace manufacturer. For further inquiries, or if you require submerged arc furnaces, electric arc furnaces, ladle refining furnaces, or other melting equipment, please do not hesitate to contact us at susie@aeaxa.com
