Cooling tower services – types of cooling towers

Cooling towers are essential for plants and industrial facilities – they are, after all, a cost-effective and energy-efficient way to remove heat from a building. Deciding your facility needs a cooling tower is easy. The hard part is deciding which one.

Marley Flow Control is one of Australia’s leading cooling tower manufacturers, suppliers, and repair technicians. Australian owned and operated, we have the experience to deliver the right solution for your cooling tower needs.

As industry leaders, we have a high level of expertise and can provide a wide range of cooling tower services. Contact our highly experienced team to discuss your options today. Or read on to discover the best cooling tower services for your business. 

What is a cooling tower?

A cooling tower is a specialised heat exchanger that allows water and air to combine to cool hot water. During this process, small amounts of water evaporate, lowering the temperature of the water that circulates through the tower.

The purpose of a cooling tower is to reduce the temperature of the circulating hot water from the condenser or machine so it can be used again in the boiler or to cool your process equipment.

How do cooling towers work?

Before we can discuss the different types of coolers available, it’s important to understand how they work.

Process Water first comes ito the cooling tower via a header to either a distribution pipe or a hot water basin. The distribution pipework/hot water basin contains nozzles and sprinklers, which sprays the water. Spraying the water helps to increase its surface area – a factor that will be important later.

By now the water is rushing at high speeds and needs to be slowed down or broken into smaller droplets to decrease the droplets surface area. The water then comes to a fill media or some sort which could be a range of materials from wood to PVC or polypropylene  to reduce its flow or surface area. Fans at the top, side or sometimes bottom of the tower are used to lift or push air through the tower.

Now that the water has been distributed evenly , is flowing slowly or been broken onto smaller droplets, and has access to air, evaporation can occur. This evaporation process is what cools the water.  

The water, which is now cooled, is then collected at the bottom of the tower, and re-used in the process. 

Types of cooling towers

Cooling towers are generally classified into three main groups:

  • Build
  • Heat transfer methods
  • Airflow generation methods

There are several sub-categories of cooling towers within these groups.

Cooling towers by build

Package type

These cooling towers are usually made from a corrosion-free, heat resistant and durable material – like Stainless steel.

Package type towers are assembled at a factory and smaller than field-erected towers. As they only come in tonnages up to around 1,500 per cell, they are compact enough to be easily transported. This makes them perfect for facilities with low heat rejection requirements – such as hospitals, shopping centres and office buildings.  

Field erected

Field erected cooling towers are much larger in size than the packaged type towers, and therefore have a bigger cooling capacity.

These towers are so large they need to be shipped to a facility and assembled on site. Once built, they cannot be transported by truck like the package type towers.

They can also be built according to custom specifications, which is ideal for oil refineries, power and steel processing plants, and petroleum sites. 

Cooling towers by heat transfer methods

Dry cooling towers

A dry cooling tower is a great option for facilities where water is limited and where regulation doesn’t allow for any kind of plume.

These towers operate by transferring heat through a surface that separates hot water from ambient air. 

Unfortunately, dry cooling towers are perhaps the most inefficient option as they use a lot of energy.

Open circuit cooling towers

Also known as wet cooling towers, these are the most popular as they are cost-effective and renewable.

Open circuit towers use water to cool machinery that has become hot by using the natural process of evaporation. The emissions released by the towers aren’t harmful at all. The ‘waste’, otherwise referred to as drift emissions, is simply heated water droplets.

Closed-circuit cooling towers

Many facilities need a tower that will protect the water from outside contamination. A closed-circuit cooling tower is ideal for this.

Closed-circuit towers, also known as fluid cooling towers, mix water with glycol to form a liquid. This liquid circulates within the tower in a coil, so it is never exposed to the air. The result is a better performing tower with low maintenance requirements.

Airflow generation methods

Natural draft cooling towers

Natural draft cooling towers use the design and shape of the tower to move up the air with fans. They are typically very tall, shaped like a chimney, and made from solid concrete.

They are often located outside, which allows warm air to naturally rise. The air is then released into the environment. These towers can be found at large facilities such as power plants.

Mechanical draft towers

These towers have a propeller or centrifugal fan located at the top of the structure which pulls the air from the side and bottom. Cool and dry air from the outside is then sucked in. Once the air reaches the centre, warm air is blown out the top by the fan.

Mechanical draft towers are far smaller than natural draft towers, so can be placed inside the facilities. The ability to monitor the speed of the fan makes capability control far easier. Mechanical draft towers generally take up as much square meters as a natural draft towers  it all depends on the duty. It way be worth not including this statement or rewording it. In a like for like situation they will never been inside.

Crossflow cooling towers

Unlike other towers, crossflow cooling towers are designed to allow air to flow horizontally, while water streams down vertically. This system requires more air than other towers as it only allows for limited air-to-water contact. 90% of the towers we sell are Crossflow towers the statement below will damage our brand; can we be a bit more positive about them.

Advantages of Crossflow towers,

  • Many different types of fills for almost any application.
  • Low sound levels, due to no water drop.
  • Easier access to water distribution systems to be able to carry out mandatory inspections.
  • Easier access to mechanical equipment to carry out routine maintenance  

Crossflow towers have some disadvantages, such as:

  • High maintenance
  • Susceptible to scaling
  • Constant clogging of openings

Counterflow cooling towers

Like crossflow towers, counterflow cooling towers also use fans to cool water down.

Hot water enters through the top, while air enters through the bottom. The water is then sprayed out via lateral pipes and splash spray nozzles into a fill. Warm, moist air moves through the fill until it is pushed out the top by the fan.

Counterflow towers are completely sealed and stored away from sunlight, so algae won’t grow inside the structure. They are also easy to maintain and energy-efficient. This statement is false in a few ways, they are harder to maintain and only have covers on them in a commercial sense not in the industrial sector. I think we should remove this   

Find out how we can use our engineering experience to help find the right solution for your business needs. Contact us here for a free quote.