A cooling tower, although simple looking, is made up of 38 different components and systems, as detailed in the list below, to ensure it operates correctly and at optimum efficiency.
- Steelwork/ base.
- Cooling tower casing.
- Access door.
- Portable crane.
- Name plates.
- External access/Maintenance. platforms.
- External ladder systems.
- External guardrail systems.
- Fan deck.
- Fan guard.
- Fan motor.
- Plume abatement system
- Drift eliminators.
- Warm water basin.
- Warm water basin guard filter.
- Spray pipework/distribution assembly.
- Fill pack.
- Air inlet louvers
- Air inlet screens.
- Internal access platform
- Cooling water basin.
- Sweeper system.
- Make up water
- Basin heater system
- Blowdown/ bleed water system.
- General pipe work.
- Control valves.
- Flow regulation valves.
- Pressure gauges.
- Electrical panel.
- Variable speed drive [VSD]/variable frequency drive [VFD]
- Control panel.
- Vibration switches.
If want to read more on Inspecting and Cleaning of a Cooling Tower read our article 'Overview | Inspecting & Cleaning Cooling Towers'.
What are the major components in a cooling tower
Below we will provide an overview of what is inside a cooling tower and what is external to the cooling tower focusing upon the major components required to allow operation.
Usually, when a cooling tower is installed, it will be mounted on a steelwork structure.
The purpose of this structure is to elevate the cooling tower, which will provide a space between the tower and the slab [roof or floor], allowing the pipework to be connected and maintenance activities to take place.
Other uses of the steel structure would be to mount maintenance platforms ladder systems, seismic systems, and wind restraints and allow vibration mounts to be mounted correctly.
Cooling tower casing
The cooling tower casing surrounds and encloses most of the cooling tower parts, such as the basin, the drift eliminators, and the fans. It also contains spray and water, allowing it to fall directly to the basin and not be carried off by the wind.
The casing can be made from galvanized steel, stainless steel, or fiberglass.
The access doors are usually mounted on the side of the tower casing and are used to gain access into the tower to inspect and complete maintenance.
A portable crane is usually purchased as an option and used to facilitate the removal of the fans and motor.
They are usually supplied to be installed and disassembled easily so that they can be moved and used between towers.
The nameplates, although small, are very important because they provide all the general design information of the tower and the fan motors, etc.
They can usually be found mounted near the door.
External access/ maintenance platforms
External access to the tower will be required, and usually, it’s broken into two parts
- ladders as described below
- and maintenance platforms
maintenance platforms will usually be installed and bolted to the steelworks structure to provide safe access, which would allow full maintenance of the cooling tower.
They will be found at the access door and sometimes at the cooling tower’s fill to allow cleaning and changing.
External ladder systems
To gain access to parts of the tower for inspection and maintenance, fixed ladders will be needed, which are usually purchased as an option from the cooling tower manufacturer.
Lattice will usually also require a lattice safety cage, an aluminum framework of vertical bars, and hoops that will bolt to the right to the sides of the ladder and are generally recommended by OSHA when the fan deck exceeds 20 feet in elevation.
External guardrail systems
External guardrail systems are usually purchased as an option and consist of posts, top rails, and knee rails which are hot-dipped galvanized.
They are usually installed on the top of the tower to provide sturdy, safe access for easy maintenance of the fan and fun deck.
Ductwork is sometimes used to direct and duct the warm moist air produced from the evaporative cooling process to the atmosphere.
This usually consists of a short circular duct mounted to the top of the tower at a 45-degree angle.
Again this is usually purchased as an option or from the ductwork subcontractor.
The fan deck is the top of the tower, where the warm moist air is discharged.
It is usually surrounded by a guardrail system to allow inspection and maintenance of the axial fans.
The fan guard is the device installed over the rotating axial fan to reduce foreign objects entering the tower when it is not operating and provide protection to any operatives working in the area.
Two types of fans will be seen, depending upon the type of tower:
- Axial fan – that is used in the induced tower, where the air is drawn up through the equipment
- Axial fan – that is used in the forced flow tower, where the air is pushed though the equipment
- Centrifugal fan – that is used in the forced flow tower, where the air is pushed through the equipment.
Each fan will have a motor that will provide drive to allow the fans to push or pull the air through the unit.
Most commonly, for the induced type tower, the motor will be mounted within the airstream, meaning a focus should be on the anti-corrosion protection to ensure the motor’s longevity.
Plume Abatement System
A plume abatement system is installed to control and reduce the water vapor that can usually be seen above the cooling tower on a cold morning.
This can be required under regulations or local codes.
See our article ‘What causes Cooling Tower Plume?‘ for a short quick explanation with a diagram.
Drift eliminators are installed above the ‘nozzles’ in a counterflow tower and mounted before the air entering the tower body for a crossflow type tower.
Their purpose is to reduce water usage by stopping water droplets from being ejected from the tower ‘drift,’ as they can be easily transported within the fans’ air stream.
In simple terms, the water is removed from the air by changing its direction through the Drift Eliminator.
Warm water basin
The warm water basin is installed at the top of the tower and used, on a crossflow tower, to feed water down into the fill pack to allow the cooling process to start before dropping into the water basin.
The basin can be made from stainless or galvanized to ensure there are no issues with corrosion.
Warm water basin guard filter.
A basin guard filter is supplied by some manufacturers and is installed to sit on top of the warm water basin to filter the water flowing down the fill pack and into the water basin.
The filter media helps clean the water removing any debris and scale before entering the nozzles, protecting them from possible blockages.
Other benefits are:
- Reduction in basis cleaning
- Reduces risk in nozzle blockages
- Protects impellers of the pumps
Spray pipework/distribution assembly
Usually factory fitted and connected to the condenser water system, a range of pipework is installed to transport the warm water, usually from a chiller/condenser, that is to be cooled, to the top of the tower, where it is sprayed or fed, depending on crossflow or counterflow, through the fill pack.
Within the tower and attached to the spray pipework will be ‘nozzles.’ These will be factory-supplied and are used to atomize the warm water into a mist for the evaporative process.
They are usually designed specifically for the type of tower being used and the volume of water needing to be sprayed by them.
- Crossflow Nozzles
- Counterflow Nozzles
Fill packs are a honeycomb/angular corrugations-like structure in which the warm water will flow through, meeting the air drawn through it.
The honeycomb structure allows more efficiency in cooling the water as it creates a much larger surface area.
Commonly, there are two types of fill pack:
- Counterflow [horizontally mounted high level in tower]
- Crossflow [vertically mounted in tower external walls]
Attenuators are usually used if there are any noise restrictions or calculated noise issues that may be seen in the surrounding areas to the towers,
They can be fitted to the intake or discharge of the units, and sometimes both.
Air Inlet louvers
Purchased as an option usually, air inlet louvres can be mounted outside the fill pack at the air intake. They have a few benefits:
- Help prevent the escape of water from the tower ‘splash out’.
- Containing the water reduces slip hazards from around the tower
- Reduce leaves and foreign objects form entering the tower
- Stop the penetration of sunlight into the tower, which helps reduce the growth of algae and biofilms etc.
An area that needs to be considered if using standard type louvres is ice build-up in winter. If there is splash out from the tower and it starts to accumulate on the louvre blades, ice could eventually build up – creating blockages and operational issues for the tower.
Air Inlet screens.
Air inlet screens are a mesh, similar to that we see mounted to the back of weather louvres. They are mounted on the outside of the fill pack at the air intake to the tower.
They have two main uses:
- To keep debris out of the tower
- To meet the FM Global Fire requirements of containing the fill inside the tower incase of fire. The inlet screen will stop the fill from falling out risking spreading the fire.
Internal access platform
Internal access platforms are usually provided as an option and are used to gain access around the internals of the cooling tower, allowing maintenance and inspections to take place.
Cooling water basin.
Located at the bottom of the cooling tower, the water basin has two uses:
- is designed to catch and allow recirculation of the cool water from the cooling process back into the condenser system and,
- to provide weight and structure for the tower
The basin can be made from stainless or galvanized to ensure there are no issues with corrosion.
The sweeper system is installed into the bottom of the water basin. It consists of pipework and nozzles that spray pressurized jets across the basin, moving and cleaning away debris that may build up from airborne and general solids from the water. It will usually be used alongside the cooling tower filtration system, helping to maintain the cleanliness and efficiency of the unit.
See our article ‘What is a Cooling Tower Sweeper System‘ for more detailed information.
To maintain the water cleanliness and remove any foreign objects and debris from the condenser water system that may have been introduced within the cooling process [scale, rust, suspended solids, etc.]. There will usually be a separate filtration system installed and operating.
The most common in our world would be the side stream filter, but the use of other types can be seen, including:
- Screen filters
- Plastic disc filters
- Sand filters
Make up water
Makeup water can be provided to the cooling tower basin by 2 means:
- Float type
- Automatic level control
The makeup water system consists of a float valve that, as the water level in the tower, will drop the float, in turn, opening the makeup water valve, allowing the water that is being lost to the cooling process and evaporation to be replaced.
Automatic level control
Connected to a water level makeup control system, multilevel probes are installed in the basin to monitor the water’s depth.
If the sensors note that the water level is low, they will signal the valve to open, allowing the water lost to the cooling process and evaporation to be replaced.
Both systems do the same thing… keeping the condenser system topped up.
Basin heater system
The basin heater is usually used as a protection against the risk of freezing.
They operate as a 24v emersion type heater [like found in our hot water cylinder at home] and are made from stainless steel to ensure protection from corrosion.
Blowdown/ bleed water system.
During the cooling process, a small quantity of water will be removed from the cooling tower via evaporation, which will leave behind its minerals and solids such as calcium, magnesium, chloride, and silica.
As more and more water is removed, the minerals and solids will become more and more concentrated. This concentration could impact the operation of the tower, chiller/condenser, and pipework systems via scaling and corrosion. Reducing the equipment’s effectiveness, efficiency and increasing the requirements for regular maintenance.
To combat the increase in solids, a blowdown/bleed water system will be installed and used.
The system will monitor the water quality in the system and, when needed, will blow down [usually to drain or another tank that will use the water for things like flushing toilets, etc.] a set quantity of water containing the concentrated solids, allowing it to be replaced by fresh, clean better-balanced water.
General pipe work.
For the tower to operate, there will be a requirement for a range of different pipework to be connected:
- Flow and return pipework – to connect the chiller/condenser to the cooling tower
- Flow will be connected to the cooling tower ‘range’ usually at the top of the tower, that feeds the nozzles or high level warm water basin, bringing the water from the process to be cooled.
- Return connected at low level to the tower to allow the cooled water to be recirculated back into system.
- Balance pipework [if using more than one tower] – to ensure that the cooling tower basins are balanced and one is not running dry whilst another is overflowing etc. Its a kind of ‘dumb’ pipe.
- Cold Water Feed – to allow fresh water to top up the system due to evaporation and blowdown
- Overflow pipework – this will be connected to allow the water to be discharged under control if the tower basin overflows.
See our article 'Cooling Tower Piping Layout and Diagrams ' for more detail on the pipework and configurations for a cooling tower / consenser water system
Control/actuated/modulating valves will be used to manage the water entering and exiting the cooling tower.
Flow regulation valves.
Flow regulation valves / commissioning stations are installed into the pipework feeding the tower to balance the system and set the correct maximum design flow rate for the tower.
Like most pipework systems, pressure gauges will be installed on the pipework entering the tower and leaving the tower. They will be used for reference during commissioning and if any problems are noted with the tower performance.
An electrical panel will be necessary to provide the correct power to the cooling tower, usually from a Local Mechanical Panel or Low Voltage Switch Board.
Variable Speed drive [VSD] / Variable Frequency Drive [VFD]
To ensure that the fan and motors are operating efficiently during different demands and loads, the VSD/VFD will vary the speed of the motor. This helps create a lot of energy savings.
The tower supplier will usually provide a simple control panel that can be used to control the items directly associated with the unit:
- Electrical On/Off
- Hand/Auto selection
- Makeup water valves and probes
- Water level alarms
- Solenoid valves
Vibration switches are used on cooling towers to monitor for any unusual vibrations and, if required, switch off the fan and its motor upon sensing abnormal vibrations.