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Cleaning of cooling towers

A cooling tower is an engineering structure designed to cool a large amount of water. Cooling towers are widely used in water recycling systems. This device protects the processing equipment from heating and destruction under the action of high temperatures. Water circulation systems are often used in metallurgy, energy, engineering, shipbuilding and other industries.

Depending on the specifics of production, two types of cooling towers have been developed – dry and wet. A closed circuit with coolant is used in dry cooling towers, and an open circuit is used in wet cooling towers.

Types of cooling towers

By contour type:

  • closed (dry)
  • open (wet)

In dry cooling towers, radiators serve as a heat transfer surface, and they are equipped with fans to remove heated air.

Схема строения сухой градирни

In a dry cooling tower, hot water is sprayed, which is mixed with cold air. Part of the water, turning into steam, mixes with the outside air and goes into the atmosphere, while the other part cools.

The object of the closed type works on the principle of cooling water inside the closed loop of the heat exchanger, which is blown by the flow of outside air. There is no direct contact between the air supply and the coolant.

Wet cooling towers are divided by the method of air transfer:

  • crossflow
  • counterflow
  • spraying
  • ejection

By a way of the organization of contact surface, wet cooling towers are divided into:

  • irrigation (counterflow and crossflow)
  • spray (spraying and ejection)

In irrigation cooling towers, the intake air is in contact with the cooled water on the developed surface of the irrigation layer.

In spray cooling towers, the water is broken up into small drops and the heat exchange process takes place on each drop.

The counterflow cooling towers are divided into tower cooling towers and fan cooling towers. Counterflow cooling towers consist of a reservoir for collecting the cooled water, a mesh sprinkler, above the sprinkler there is a hot water system with nozzles. Hot water flows through the nozzles, mixes with the outside air, cools and enters the tank. External air is supplied through the sprinkler due to natural air convection or by blowing it with a fan. If the flow is in natural mode – this is a tower object, if it is injected, then a fan one.

Изображение вентиляторной градирни
Fan type

Fan cooling towers provide good cooling of water with a drop of up to 30°C.

Изображение башенной градирни
Tower type

Tower cooling tower has the appearance of a conical pipe of reinforced concrete or metal. Inside it has a water supply system, a sprinkler and a reservoir. The flow of external air through the inlets in the lower part of the pipe rises up through the sprinkler by creating a natural draft in the pipe.

These towers are widely used in large-scale industry because of its ability to provide greater heat output due to the huge amount of water. As a rule, they are installed next to CHP and NPP.

Изображение трех башенных градирен

In wet cooling towers, heat is transferred from the liquid through surface evaporation.

Since the main application of the cooling tower was found in large-scale industries, circulating water is used for cooling. After using heat exchangers, water accumulates excess heat, which is eliminated in cooling towers. At the same time, water is subjected to repeated physical and chemical influences – it is evaporated, aerated, polluted, etc.

Оборотная схема водоснабжения
Reverse water supply plan

As a result, there is a decrease in the volume of water by evaporation, which leads to its mineralization and, as a result, an increase in the corrosive properties of water and an increase in the deposits of mineral salts. In addition, in the process of collecting water is often contaminated with other substances.

During operation, cooling towers, like any equipment and mechanisms, become contaminated and wear out, which entails:

  • deposition of limescale on the working surfaces, magnesium and calcium carbonates precipitated resulting in the process of continuous cooling of water;
  • deposits resulting from corrosion of metal structures make it difficult to complete the work;
  • solid particles including sand, stone fragments, and clay having a sufficiently large size and weight to settle to the bottom and clog spray nozzles;
  • non-precipitated and undissolved suspensions. These are feathers, small insects, poplar wool. They can be dangerous for valves, pipelines and heat exchangers;
  • pollution of circulating water by insoluble particles, which clog the nozzles, settle in pipelines and cooling tower basins;
  • contamination by algae that form in the equipment system and create a risk to human health.

Stages for cooling tower cleaning

Cleaning a cooling tower is an extremely important technical process that must be performed by professionals. For the normal functioning of the equipment, it is necessary at least once a year to process the cooling towers. ASGARD-Service Company offers services for cleaning and chemical flushing of the cooling tower in Moscow and the region.

A hydrodynamic, mechanical, chemical or complex cleaning scheme is used for cleaning of cooling towers.

When working on cooling tower cleaning, the specialists of ASGARD-Service act according to the following scenario:

  1. They conduct a visual inspection and assess the status of the cooling towers.
  2. They choose the most appropriate cleaning technology, select the most suitable reagents for cleaning.
  3. They directly clean the cooling tower.

Cleaning involves several stages:

  • turning off the cooling tower from the general system
  • removal of water from the cooling tower
  • chemical cleaning
  • hydrodynamic cleaning
  • disinfection of the cooling tower with special preparations.

Hydrodynamic cleaning is carried out by powerful water-pressure installations allowing to remove any complex deposits.

Chemical cleaning is carried out using special foam reagents of neutral nature allowing to remove deposits in hard-to-reach places and at the same time remove dangerous microflora without causing corrosion processes.

Removing contaminants from all structural elements of cooling towers: injector nozzles, water distribution pipelines, internal and external parts of the sprinkler.

For each type of cooling tower, depending on the cooling method and type, the company has developed flow charts.

The quality of the result cleaning is controlled visually, in remote areas with the help of robotic video control systems. The absence of pathogenic microflora in the cooling tower system is monitored in accredited laboratories.

Specialists working on the tasks of cleaning have all the necessary tolerances and permits.

The equipment is cleaned by certified personnel who have many years of experience in this field, which also guarantees results.

Chemical cleaning of cooling towers is carried out depending on the nature of the cooling tower operation and taking into account the intensity of equipment operation, at least 1 time in 2 years.

Cleaning of cooling tower with a hydrodynamic method is carried out at least 1 time per year.

In case of a task to clean any type of cooling tower, contact our company! The specialists of ASGARD-Service will advise you on the issues of the established task, will promptly carry out the visit and inspection of the object, will calculate the cost of work. We are professionals in the field of industrial cleaning, and you can confidently entrust your building to us.