How do mobile towers work

Cooling tower, hybrid cooling tower, wet cooling tower: function, comparison & manufacturer

Whenever a lot of excess heat has to be removed from a process, cooling towers (including recooling plants) are used. These transfer thermal energy to the ambient air and are available in different types. But how do the solutions work? When is which type of cooling tower used and what needs to be considered in terms of hygiene? Deutsche-Thermo.de provides the most important information and shows when system operators can buy or rent a cooling tower.

The topics at a glance

Cooling tower: how the dry coolers work simply explained

The principle of a cooling tower is based on the evaporation of water. Finely distributed water droplets give off thermal energy to cool air. The air heats up and usually flows out of the cooling tower unused. A wide variety of components are required for the technical implementation of this mode of operation. In addition to a system for distributing the cooling water, so-called cooling installations and fans are particularly important. In addition, water collecting trays, droplet separators and stable housings are used.

Cooling tower distributes the water to be cooled in its interior

As a compact unit, all components of the industrial cooling tower are in a protective cover made of, for example, moisture-resistant plastic. The cooling water flows from the connected system into the recooler and is distributed through numerous nozzles on the cooling installation (the cooling surfaces) in the interior. This process creates a large surface and ensures that some of the water evaporates. This effect removes energy from the cooling water and ensures a high cooling tower efficiency. It lowers the temperature of the water, which then collects in a tub in the bottom of the recooling plant. Here a pump supplies the cooling water to the connected process cooling again.

Fans ensure a flow through the recooling plants

Air from the environment absorbs the excess heat from the cooling water. In order to ensure that this is available in sufficient quantities, fans are predominantly used in industrial cooling towers and evaporative cooling systems. These can either be at the bottom of the air inlet or at the top of the air outlet from the cooling tower. While the former press ambient air through the dry cooler comparatively quietly, the latter work with suction. They generate a negative pressure in the recooling plant, through which the fresh air automatically flows in from the outside. Even if suction systems are louder, they have a decisive advantage: They are better protected from frost in winter. Because the air that exits the unit at the top is significantly warmer than at the entrance to the cooling tower.

Cooling tower: the function of the droplet separator saves cooling water

Before the warm and humid air exits the cooling tower, it passes a droplet separator. This is a heat exchanger with large contact surfaces on which part of the moisture carried along condenses. The installation reduces the so-called drop loss. The air flows out of the cooling tower in a drier manner and the cooling medium requires less make-up water. The latter compensates for the drop losses and ensures that the connected system or the connected process has sufficient cooling water available.

An overview of the different types of dry coolers

Depending on the area of ​​application, different dry coolers are possible today. So there are the wet cooling towers already presented with open and closed circuits. In addition, drying and hybrid cooling towers are also available on the market. The following table shows what makes up the different systems.

Wet systems are simple, reliable and comparatively inexpensive. They are always used when water is available in sufficient quantity and quality. If system operators have to transport the cooling medium to the system and / or process it in a complex manner, dry coolers are an efficient alternative.

Evaporative cooling systems are notifiable according to the 42nd BImSchV

Since the exhaust air from wet dry coolers can be contaminated with legionella, operators of such a system have to adhere to numerous specifications. These are regulated in the 42nd BImSchV, which among other things contains an obligation to notify all evaporative cooling systems. Operators have to report new installations, changes, shutdowns and recommissioning. In addition, the legislature requires the certification of the cooling tower hygiene with a regular microbiological examination. If there are legionella bacteria in the cooling tower, this must be reported immediately when certain limit values ​​are exceeded. Furthermore, the BImSchV makes operators more responsible. It obliges them to regularly check and maintain their systems. An inspection by an expert and a risk assessment for the cooling tower is also mandatory.

Alternative: The cooling tower for large power plants

In addition to the comparatively small recooling plants for air conditioning and industrial applications, there are also very large systems. These are used, among other things, in power plants to dissipate excess thermal energy. One of the most powerful cooling towers in the world is the tower of the Isar nuclear power plant in Bavaria. It has a height of 165 meters and can cool down 216,000 cubic meters of water every hour.

Energy-saving: Free cooling with the cooling tower

If the cooling tower supplements a cooling system, its energy consumption can often be reduced noticeably in winter and in the transition period. This is possible with free cooling, whereby the dry cooler completely or at least partially replaces the actual cooling process of the compression refrigeration system.

Use of cooling towers in air conditioning and industrial technology

The recooling plants are always used when large amounts of heat need to be dissipated cost-effectively. The installation of a cooling tower in industry is typical. Here it lowers the temperature of the cooling water from technical processes. Further areas of application can be found in chemistry or in the food sector. The dry coolers are also used in refrigeration and air conditioning technology. Here they dissipate the heat from water-cooled air conditioning units or from a water chiller.

Design the recooling system: providers help with the calculation

In order for the dry cooler to work efficiently and reliably, experts have to calculate the cooling tower. This is possible according to a standardized process, as the following overview shows:

If problems arise during planning, experts jump back a little in the process to reconfigure the cooling technology.

Cooling tower: costs of acquisition and operation

How much can a cooling tower cost? A general answer to this question is not possible. Because the prices of the energy-saving dry coolers depend on numerous factors. In addition to the performance, it also depends on the type, the water treatment and numerous other specifications. System operators can only get reliable information on the price list with an offer from a manufacturer / provider. The experts also support operators in planning. They design the technology precisely and help to determine the operating costs incurred.

Buy or rent cooling tower: which is better?

If you use the dry cooler in your own system for a long time, you usually save a lot of money with the purchase option. However, the high acquisition costs are then disadvantageous. In addition, the lead time for the purchase option is usually longer. In the event of a planned repair or if their own drycooler has failed, operators can also rent a cooling tower. this usually makes sense if you also rent the associated water chiller. The systems are then usually available very quickly. The costs are comparatively low and production can continue.