The cooling tower is commonly being founded in most industrial facilities such as chemical plants, oil refineries, thermal power stations, and other manufacturing plants. It is used to remove excess heat by transferring the thermal energy from one medium to another in order to ensure the production process does not make the equipment or product overheat and the production system can operate efficiently. During the industrial process, water is heated up by air conditioning condensers or other equipment. The hot water will then be pumped through pipes into the cooling tower. When the hot water and air come in contact with each other, a small volume of water evaporates to lower the temperature of the water and release unwanted heat to the atmosphere. The colder water goes out of the cooling tower and is pumped back to the industrial process to absorb heat again, and the process repeats. A larger surface area in which the air and water interact means more efficient evaporation and a faster cooling process. Plants and facilities require a reliable and efficient cooling tower to dissipate the heat generated from the equipment and keep the working environment cool with the aim of reducing the risk of fire or breakdown.
Few important components in the cooling tower that you should know
Fan: A fan that is used to circulate and direct the air throughout the cooling tower. It can be either axial or centrifugal fan depending on the application requirement.
Fill: Fill normally consists of textured polyvinyl chloride (PVC) and has ridges with open spaces that allow the air and water to pass through while collecting the water on it. It maximizes the surface area of the water and facilitates the transfer of heat within the cooling process.
Spray Nozzles: They are used to disperse water into smaller droplets and increase the surface area of the water for air contact. They help to distribute the water evenly over the fill or into the air.
Collection Basin: It is located at the bottom of the cooling tower and is used for collecting the water after it has cooled down.
The cooling tower is available in a wide range of sizes that range from a few square feet small to several hundred feel large. They have different load configurations and come in different shapes and designs. You should choose and design the cooling tower that brings the highest efficiency to your application and business. Before choosing the right cooling tower for your business, you have to know its advantages, disadvantages, and other factors such as the capacity, size, level of efficiency, noise level, and tendency toward corrosion. Here we will introduce a few types of cooling towers for your industrial plants.
Cooling towers can be designed in multiple ways. The air flows can be either vertically or horizontally, the position of the fan, and whether to use mechanical fans or natural convection.
The cooling tower is normally categorized by the way of water and air flow through the tower. There are two types of design which are crossflow and counterflow.
Crossflow
Crossflow cooling tower is the simplest model that uses gravity to send hot water flow down vertically from the distribution basins located at the top of the tower. It uses splash fill to let the air come in horizontally and flow across the falling water to cool down the water temperature. This design allows the air-to-water contact in cross flows and that is the reason behind its name. However, this type of cooling tower is less efficient as it is more prone to freezing and the fill is more likely to build up with debris or dirt, especially in windy and sandy regions. This design also requires a higher power consumption for more air to come in to complete the process because it has a lesser air-flow contact time.
Counterflow
This type of cooling tower is named counterflow was because the water and air come into the cooling tower from the opposite ends of the tower. The hot water enters from the top, whereas the air enters from the bottom of the tower and flows upwards counter to the water flow in the fill media, and then the air exit from the top. This type of cooling tower uses pressurized spray nozzles and a piping system to spray the water evenly over the fill media. Because of the spray distribution, it provides greater efficiency and is more resistant to freezing than a crossflow cooling tower. Counterflow requires a higher initial cost and needs larger pumps to push air against the flow of water, it may generate higher energy consumption and lead to operational inefficiencies. This cooling tower also produces greater noise as the water has farther to fall from the fill media into the cold water collection basin.
In terms of the air-flow generation methods, the cooling tower can be classified into the following types:
Induced Draft
Induced draft cooling towers refer to the use of mechanical components such as a fan system to channel the air through the tower. The fan is located at the top of the air outlet that pulls cool air through the water and induces hot moist air out of the discharge outlet. The induced draft cooling tower is able to move the air at a high velocity that sends air far away from the tower to avoid unwanted re-circulation.
Forced Draft
The forced draft cooling tower is similar to the induced draft cooling tower, but the location of the fan is not the same. The fan of a forced draft cooling tower is positioned at the air intake instead of the air outlet. These fans are normally placed on the sides or at the bottom of the tower to force the air into the tower. It takes the air in at a high velocity but discharges it at a lower velocity. In this case, forced draft cooling towers are more susceptible to the unwanted air re-circulation due to the low exiting velocity and this may cause inefficiency in the long run and require more power. The forced draft cooling tower is very suitable for indoor facilities and can be installed in a more confined space as it has the ability to work with high static pressure.
Natural Draft
Natural draft is also known as a passive draft cooling tower that uses natural convection. Unlike the mechanical cooling tower, the shape and design of the natural draft cooling tower allow the air to flow naturally throughout the tower. Since the dry cool air is less dense than the warm moist air, warm air rises and cold air falls after the air-to-water contact. The difference in air density creates a constant movement of the air that cools down the incoming water and releases heat in a stable pattern. The natural draft cooling tower is normally featured a steep chimney design to enhance the flow of the air. It is suitable to be installed outside of the building to have a better airflow environment.
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