Is this the first time you have to deal with the cooling of your industrial plant? Or maybe do you wish to see a complete reference framework to carry out this task for your company?
These guidelines will help you choose the best cooling technology for your plant’s specific project needs.
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by Giorgio Lorenzetti, Technical Advisor at MITA Cooling Technologies
Generally speaking, different fluids require different cooling systems; or, better still, some systems are preferred to other ones according to the type of fluid to be cooled. For example, if you have to directly cool process water you could choose an open-circuit evaporative cooling tower, built with materials suitable for the purpose. This is particularly true if you have to deal with partially dirty or aggressive water.
On the other hand, refrigerant gas condensation can be better achieved by means of an evaporative or adiabatic condenser.
The building context is a further element conditioning your choice: there can be both problems relating fluid nature or spaces available for installing the cooling system, consider.
Visual-environmental impact (dimensions of the equipment) or acoustic issues are also of importance: they should not be neglected while choosing your cooler. Today there are technical measures to reduce noise levels of both evaporative and adiabatic coolers.
Some MITA ProjectA further element directs the choice towards the type of equipment most suitable for the case: that is, the type of cooling that you want to achieve. For example, direct or indirect cooling (in this case via an exchanger).
It is also necessary to consider how “delicate” the plant is, both in terms of management and any maintenance interventions: an industrial plant must ensure production continuity and medium-long maintenance intervals. On the other hand, an air conditioning or seasonal operation system is usually subject to scheduled checks and controls during periods of inactivity.
In this sense, an open or closed circuit evaporative cooling tower or (in the case of refrigerant gases) an evaporative condenser, can be more “robust” systems than an air or adiabatic cooler. The latter, may be more subject to getting dirty in the area of the finned coils when installed in an industrial plant.
An “economical” cooling system may not be the most efficient at the same time. It is necessary to make a careful overall and preventive evaluation of both the initial investment and the return on investments in terms of direct (system efficiency) and indirect (reduced need for maintenance) benefits .
In this sense, it is better to opt for a more efficient and suitable system for your needs in perspective, rather than being conditioned by the cost of the equipment.
In addition to the thermal power to be dissipated, the decisive element is the temperature at which you want to cool the fluid or condense the gas: it is useless to exceed downwards if it is not strictly necessary. In fact, many processes only need to dissipate more or less high amounts of heat: therefore without having to reach lower limits that would be stressful for the equipment.
The thermo-hygrometric conditions of the place of installation must decisively direct the choice towards the best cooling system.
A geographical area with low temperatures, even if with high humidity, will affect the choice towards air systems. While areas with high average temperatures and humidity will convey the choice towards evaporative or, at least, adiabatic systems.
This is obviously not an absolute rule: what has been said above applies to the lower temperature limit of the fluid or gas required and the size of the system. However, an appropriate choice in this sense makes it easier to achieve efficiency and optimization both for installation and management costs.
As for the previous point, the thermo-hygrometric characteristics provide a precise reference in relation to the lower limit that can be reached by the cooling water or, at least, which system to use to reach this limit.
Some processes, for example the molding of plastic materials, generally require rather low cooling water temperatures: to the point of requiring refrigeration units possibly combined with evaporative or dry systems in cold seasons. These are therefore rather complex systems, which are able to combine different cooling situations and to offer maximum efficiency in the various annual climatic conditions.
We are talking about a series of factors peculiar to the system or the installation area: ice, aggressive water or to be kept clean, silence for nearby civil buildings, …
Further important elements of choice: the type of plant facilities in which the cooling system is to be installed (i.e. civil, commercial, industrial) as well as the plant size. Civil or commercial users of small and medium thermal power (up to 1 MW) are preferably served by air or adiabatic systems. The remaining industrial and / or medium-high thermal power users are generally subservient to evaporative cooling systems: they are more compact, economical and efficient.
The specific operating conditions of the system constitute another determining element: continuous operation, for example, implies that the equipment must operate without problems in opposite climatic conditions. Instead, an installation in an urban context, or in any case sensitive to the “noise” aspect, must be able to guarantee very low noise levels and in compliance with the regulations in force.
Discover MITA solutions for different installation contextsThe “physical” dimensions of the necessary cooler must be considered not only to assess whether the space that you plan to dedicate is sufficient, but also to limit visual impacts that can sometimes represent a constraint.
Of course, the other factors listed above have priority in orienting the choice of the best cooling technology.
Logistics also has its importance in choosing the best solution. The availability of water or not can point towards a water or air system. Furthermore, the presence of a previously built system (as in the case of a replacement), can condition the choice in order to optimize the construction costs.
The term “logistics” also includes the choice of the physical positioning of the cooling system: some installations are made on the roofs of both industrial and commercial buildings due to space problems: this implies bringing electrical and hydraulic power supplies to a height.
Buying a “cooling system” requires adequate pre-sales consultancy support and the guarantee of a reactive and efficient after-sales service.
Some companies have structured themselves to provide the customer with complete “packages” which include also technical rooms within which they are inserted in addition to the cooling system itself: the circulation pumps, the electrical panel, the water treatment system and hot and cooled water collection tanks. The customer only has to bring the hot water and cooled water pipes to the offered system.
Subsequently, the entire management of the cooling “kit” is entrusted to the panel that manages the system. Generally speaking, all this can be equipped with a connection for remote control with a view to industry 4.0.
Find Out All MITA pre- and after-sales servicesIn the context of the after-sales service mentioned above, another point to consider is the assistance relating to scheduled and extraordinary maintenance of the cooling system. Each equipment must be equipped with a control and scheduled maintenance plan. Nevertheless, the best solution is to rely on a Company which includes Service as an activity: a presence alongside the Customer at periodic deadlines to check all cooler’s conditions.
You will get efficient and thoughtful service from CHT TECK.
After-sales assistance service has the same importance than the support than technical-commercial advisory phase, if not even greater: the after-sales service must be continuous and always fast and effective. A kind of constant presence alongside the customer for optimal plant management.
The cooling tower is nothing but a device used to reduce the heat and increase production efficiency. In simple words, it is used to cool industrial hot water. Its size ranges from tiny to massive towers based on the requirement.
A cooling tower’s main function is to remove heat from water by evaporating a little amount of it. The mixture of warm and cooler water leads to latent heat evaporation causing the water to cool. A commercial cooling tower has an average life expectancy of 15-20 years.
Several industries use a cooling tower, such as chemical manufacturing plants, primary metals processing plants, petroleum refineries, rubber products manufacturing plants, tobacco manufacturing plants, glass manufacturing plants, and textile manufacturing plants.
The cooling tower provides high cooling efficiency, needs less maintenance, consists of reliability and sustainability, and can be operated for a longer duration. Now, let us have a look at a few questions that will help you get clear with the idea behind cooling towers.
1. What is a cooling tower?
A cooling tower is nothing but a heat exchanger. It extracts waste heat to the atmosphere by cooling the water stream to a lower temperature. Water begins to cool when it comes into contact with air. In this way, the same amount of water is evaporated and thereby cool down the hot water.
2. What are the different types of cooling towers?
There are two types of cooling towers:
3. What is an Evaporative cooling tower?
Cooling is provided via an evaporative cooling tower based on a design wet-bulb temperature. This cooling tower can cool water to 85 degrees Fahrenheit. It is the most economical option for cooling a large amount of water.
4. What is entering wet-bulb temperature (EWBT)?
EWBT is nothing but a device that measures the level of humidity in the air entering the cooling tower. The higher the temperature of the wet bulb, the more moisture exists in the air. The cooling tower needs to be larger with a high wet-bulb temperature compared to a lower wet-bulb temperature.
5. What is the difference between ‘counterflow’ and ‘cross flow’ cooling towers?
In a counterflow cooling tower, air travels vertically upwards through the fill and makes intimate contact with water. Hence, both air and water are in opposite directions. In a crossflow tower, air passes through the fill horizontally, crossing the downwards water flow.
6. Why choose the FRP cooling tower?
FRP (fibreglass reinforced polyester) is mixed with a gel coating that protects the cooling tower from direct UV rays. Additionally, it also provides a higher resistance to rot and decay to all FRP portions. Hence, FRP cooling tower manufacture is considered in extreme climate conditions.
7. How do Cooling Towers Operate in Cold and Sub-zero Weather?
In cold weather, the cooling tower is operated with a heat load. The operating water flow is directly bypassed to the cold-water basin to prevent icing if the heat load drops too low. The water flow is maintained over the cooling tower.
8. What is the difference between a ‘Force Draft’ and ‘Induced Draft’ cooling tower?
A Force-draft cooling tower imparts an agitation system that forces air into the tower, and fans are positioned on the side of the cooling water. Meanwhile, induced draft tower works by pulling air from the building and fans are located on the top of the cooling tower.
9. How is Water Loss Calculated in Cooling Tower?
There are three types of water loss in the cooling tower: drift, evaporation, and blowdown. Drift loss is while circulating water for the natural draft tower. Evaporation loss is simple as it sounds, water loss due to evaporation. Blowdown loss is during circulating water that lowers the concentration of solids.
10. What is Cooling Tower Drift?
Drift is undesirable loss of water to the environment through tiny, unevaporated droplets in the existing cooling tower stream. These water droplets carry minerals, microorganisms, debris, and chemicals from the circulating water. Hence, it potentially impacts the environment.
11. What is the regulating organization for cooling tower technology, and where can you learn more about the cooling tower industry?
There’s a worldwide industry named Cooling Technology Institute (CTI) authorized on cooling tower technology. In this institute, there are manufactures, owners/operators, and supplies providing facilities for the cooling tower. Moreover, you can get more information on CTI guidelines and specifications on the CTI site.
12. How to clean Air Inlet Louvers of Cooling Tower?
The best method to remove the minerals from the air inlet louvres is to remove the louvre equipment and let them soak in the cold-water basin of the unit. The chemicals present in the water treatment unit will neutralize and dissolve the minerals buildup. The time depends on the severity of the buildup.
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