Keys for the maintenance of evaporative cooling equipment
Given your interest, we transcribe here the article published in Caloryfrio.com
The maintenance of cooling towers and evaporative condensers is a simple process that provides numerous advantages. The first is to prevent the proliferation of Legionella bacteria; the second, to optimize the performance and the useful life of the equipment. To a correct maintenance, the technical innovations introduced in the equipment in both directions over the last years are added.
The principle of evaporative cooling is a natural process that uses water as a refrigerant and is applied to the transmission of excess heat from different processes to the atmosphere. This principle is based on the operation of equipment such as evaporative condensers and cooling towers, facilities that play a fundamental role in the industrial and business fabric of the country.
Contributions of evaporative cooling to the industry
The technology of evaporative cooling is used in almost all industrial applications where cold is needed: petrochemical and pharmaceutical industries, food, automotive industry, steel production, manufacture of electronics and semiconductor components, power plants, cogeneration plants, industrial refrigeration and machinery. It is also used in domestic air conditioning, including shopping centers and large office buildings, hotels and hotel complexes.
Its main contributions to the industry reside in its own innate characteristics:
- Respectful with the environment: it is a clean and respectful technology, since it uses water as a coolant, a natural element that does not contribute CO2 emissions, favoring both the reduction of its consumption and its efficient use.
- It favors the saving of electrical energy: the reduction of the energetic consumption and of the gas leaks is achieved by the efficiency in the process and the high performance of the equipment. As an example:
– In an air conditioning installation, water condensation equipment – cooling and evaporative condensers – offer, compared to air condensation, savings of up to 45% in consumption.
– In the refrigeration installations, the powers absorbed by the evaporative towers and condensers are significantly lower compared to the air.
- Reduction in water consumption: evaporative cooling reuses more than 95% of the water it mobilizes in its operation, a small amount evaporates and another is evacuated to avoid the concentration of salts. In origin, it consumes less water than air condensation, since a power plant consumes approximately 100 liters. of water for each kWh generated
- Reduced acoustic pollution: due to the fact that these devices require a lower air flow than those cooled by air, with 9% less sound pressure than adiabatic and 7% less than dry systems. According to a report from ICAEN (Institut Català d’Energia), hybrid equipment emits the most noise.
- Lower average initial investment and rapid recovery thanks to the savings generated.
- Quick and easy installation, as long as no major works are required.
- These equipments are up to five times less heavy and bulky than those of air condensation.
- Its useful life has increased thanks to the use of materials resistant to corrosion and to maintenance treatments that, in addition to guaranteeing protection against Legionella, optimize the operation of the equipment.
Maintenance of equipment
The actions developed around the maintenance of evaporative cooling equipment are aimed at promoting the tasks of cleaning, disinfection and control of water temperature. This work has the effect of avoiding the risk of reproduction of legionella bacteria but also helps to optimize the energy efficiency of the equipment, its correct functioning and its useful life.
Two years ago there have been no outbreaks associated with refrigeration equipment. The increased awareness among owners and installers about the need to perform a proper maintenance ensures the safety and efficiency of this technology.
The maintenance of the evaporative cooling equipment is simple and with it its effectiveness and safety are guaranteed. It is vital to maintain the performance of the installation, in order to ensure optimal operation of the cooling process and the minimum use of water and energy; at the same time that the uncontrolled proliferation of bacteria will be avoided. The requirements to maintain the effectiveness of any system go through the proper control of the quality of the water in recirculation and a maintenance program that contributes to the good conditions and cleanliness of the equipment. However, in order to perform good maintenance, other issues must also be taken into account:ç
- Know and apply Royal Decree 865/2003, of July 4, establishing the hygienic-sanitary criteria for the prevention and control of legionellosis. Its compliance is mandatory and simple. It establishes the basic maintenance conditions that must be followed to ensure environmental safety.
- Follow the recommendations of the equipment manufacturers. These are safe with proper maintenance and the protocols recommended by the manufacturers, which follow the guidelines established in the aforementioned Royal Decree, are simple and easy to comply with.
- Ensure the correct operation of the equipment. The operation of the equipment in uncontrolled conditions is one of the reasons that can contribute to an outbreak of Legionella. This situation occurs when controls and periodic cleanings recommended by the manufacturers are not kept up to date. It is important to respect the periodicity of the same since, otherwise, the accumulation of dirt and scale will be difficult to clean, making it necessary to stop the equipment for a long period of time in clean conditions.
Typical concentrations of a total of aerobic bacteria of 104 cfu / ml (cfu = colony forming units) imply that the system is under control; Nevertheless; Concentrations above 105 cfu / ml require immediate corrective measures to reduce the bacteriological level. There are conditions that favor high concentrations of bacteria, especially Pneumophila Legionella:
- Temperature: bacteria do not multiply below 20 degrees even if they are still alive, while above sixty do not survive.
- Nutrients: in the installation there must be nutrients that allow the multiplication of bacteria, that is, sediments, mud, traces of corrosion, etc.
- Shelters: the mud, the biological films and the inlays can offer shelter to the growth of the Legionella.
A correct cleaning and disinfection of the installation will prevent the production of any of these circumstances, eliminating the risk of Legionella.
- Take care of the design of the equipment. If the team is twenty years old or older maybe the time has come to renew it. Currently, the design of evaporative cooling equipment includes improvements designed to eliminate the conditions that favor the multiplication of bacteria, as well as to minimize the dragging of water aerosols in the air discharge of the equipment.
- Monitor the installation site. The Law is clear in this regard, the equipment can not be placed in people’s passage areas to prevent the steam plume they emit from being inhaled by them. From the Technical Commission of AEFYT we are sure that a hypothetical bacterium contained in microdrops would not survive more than a few meters, so if the new tower is installed in a correct location of the equipment, according to the legislation, it will reduce and even eliminate, the possibilities of inhalation by people. There are serious doubts that the bacteria can survive several meters inside the microdroplets, so the site is vital to avoid being inhaled.
- Ensure that maintenance control books are up-to-date and ensure that they are carried out by reputable companies. In this sense, in recent years there has been an intense professionalization of the maintenance sector, as well as a greater awareness of the importance of doing a good job in this regard.
- Legionella is fought in winter. The maintenance of a tower is a task that must be carried out with the periodicity recommended by the manufacturer throughout the year.
- An exhaustive control of the water supply network. It must be borne in mind that in order to form a virulent colony of Legionella Pneumophila, it has first had to produce a water supply with said bacteria through the network. In this sense, the control of the water network and, therefore, of the origin point of origin of the bacteria is essential to avoid outbreaks. The exhaustive control of water network ensures the tranquility of the citizens, to the extent that water reaches places as close to them as sprinklers, swimming pools, public fountains and even wells from which water is extracted for irrigation or other uses .
- Breaking the chain of events that favors the appearance of possible legionella buds in the towers in any of its links. In order to produce an outbreak of legionella in a water cooling equipment that reaches the environment, a highly unlikely chain of events must occur: the arrival of a virulent Legionella colony through the water supply network, the operation of the equipment in uncontrolled conditions, the discharge of an air stream with contaminated microdroplets in suspension, which can reach people where they are and a sufficient number of these microdroplets are inhaled by people susceptible to contracting the disease. If any of these links breaks, the possibility of the appearance of an outbreak is null. The fulfillment of the previous councils will break this chain.
- To the extent that many cases of legionella have their origin in equipment and facilities as disparate as nebulizers and hot water facilities must influence the proper maintenance of other equipment at risk, which is sometimes neglected to not suffer the same social pressure and administrative experience that the cooling towers experience. Their owners must be aware of the need to perform proper maintenance to avoid the possibility of bacterial growth.
Technical innovations
To all these circumstances we must add the technical advances registered in recent years, which contribute to facilitate the maintenance of equipment and reduce the risk that these house and spread colonies of legionella.
In addition to achieving greater energy efficiency, easier maintenance has been achieved which, consequently, results in socio-health safety. This is the case of:
- High efficiency fillers that have been transformed with the use of resistant materials – polypropylene and polyester.
- The droplet separators, which have undergone a similar evolution in terms of efficiency when it comes to preventing the outflow of water droplets.
- The improvement of accessibility, through large doors that facilitate the entry of technicians; the evolution in systems to facilitate drainage, cleaning and sampling, which translates into inclined trays, platforms and stairs.
- New windows, whose design avoids the passage of light or water that carries dirt, preventing the ultraviolet rays from causing the necessary conditions for the microbiological development inside the tower.
Conclusions
Evaporative refrigeration equipment is one of the most efficient alternatives in the field of industrial refrigeration, to the extent that they use a technology that respects the environment, require an investment lower than that demanded by similar solutions and, above all, are safe for human health.
A simple and constant maintenance of the facilities will help to guarantee the thermal performance of the equipment and to prevent the growth of potentially harmful micro-organisms, such as Legionella.
Technical Committee of AEFYT
Control y Ventilacion, S.L. is a company of international renown within the industrial and livestock sector, for being a manufacturer of products within the evaporative cooling sector, such as the HUMIBAT, evaporative plastic cooler; or its NUCLEOS towers, Cooling Towers. In both products, the substrate in which the evaporative process is produced is a plastic honeycomb, a honeycomb resistant both to physical and chemical attacks, and at the same time flexible, a honeycomb with a mesh structure, made of polyethylene High Density, and marketed under the names of PANAL C & V or in the case of being a drop separator, SEPARADOR C & V .
For more information you can see the following links:
www.controlyventilacion.com/refrigeracion-evaporativa/
www.controlyventilacion.com/relleno-y-separador/
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