Refrigeration unit maintenance: two cooling tower cleaning schemes and processes

April 9, 2024

Refrigeration unit maintenance: two cooling tower cleaning schemes and processes



The cooling tower is exposed to the outside for many years, and the fan's adsorption force is strong, causing a large amount of sediment and dirt to enter the tower. Prolonged operation will gradually reduce the cooling capacity of the cooling tower, and the outlet holes of the water distributor are easily blocked. Sediment and dirt can also easily enter the cooling water system, which will directly affect the normal cooling of the cooling water system. To prevent the above situation from happening, it is necessary to regularly clean the cooling tower.




Process flow of cooling tower cleaning treatment plan




Option 1: Shutdown cleaning

Follow the cleaning process to sterilize and kill algae, clean with cleaning agents, pre film, and clean after cleaning. This plan requires a cleaning time of about 8 days in a shutdown state, with a descaling rate of over 95%.

Cleaning procedure: water flushing - sterilization and algae removal cleaning - cleaning agent descaling cleaning - washing after cleaning - pre film - cleaning after cleaning


1. Water flushing


The purpose of water flushing is to flush out loose dirt such as dust, sediment, detached algae, and corrosive substances in the system as much as possible with high flow rate water, while checking for system leaks. The flow rate of flushing water should be greater than 0.15m/s. After passing the flushing, the flushing water in the system should be drained.


2. Sterilization and algae killing cleaning


The purpose of sterilization and algae removal cleaning is to kill microorganisms in the system and cause the biological sludge attached to the surface of the equipment to peel off and detach. After draining the flushing water, add bactericidal and algal agents to the system for cleaning. Stop cleaning when the turbidity of the system reaches equilibrium.


3. Cleaning solution for descaling and cleaning


The purpose of cleaning with cleaning solution is to use cleaning agents to dissolve scale and oxides in the system and rinse them off with water. Add the cleaning agent to the central air conditioning system and use a circulating pump to clean it in a loop. Evacuate at the highest point and discharge at the lowest point to avoid air resistance and clogging of the drainage system, which may affect the cleaning effect.



During cleaning, the concentration of the cleaning solution, metal ions (Fe2+, Fe3+, Cu2+) concentration, temperature, pH value, etc. should be regularly checked. The cleaning should be completed when the metal ion concentration tends to stabilize.


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4. Rinsing after cleaning

This water flushing is to wash away the residual cleaning solution and impurities during cleaning. The flushing requires continuous opening of the guide vanes to flush away the impurities and residues deposited in the short tube. Rinsing is a continuous testing of pH and turbidity, and ends when the pH and turbidity tend to stabilize.

5. Pre film

The purpose of pre coating is to form a complete and corrosion-resistant protective film on the metal surface that is in an activated state after cleaning or on the metal surface where the protective film is damaged.

6. Cleaning after cleaning

After cleaning the cooler and evaporator, the main unit's cooler and evaporator should be opened and the cooler should be flushed one by one using a dedicated pipe opener. Due to the water circulation system of the cooler being exposed to the atmosphere and the high heat exchange temperature, the scaling condition of the cooler will be more severe than other places. If necessary, the cooler should be cleaned and descaled separately by connecting an open circulation system to ensure that every copper pipe in the cooler is unobstructed. Rinse the evaporator with high-pressure water to thoroughly remove any impurities that have settled inside. If necessary, clean the evaporator separately from the external circulation system.

Cooling tower cleaning: Due to the exposure of the cooling tower to the atmosphere, a large amount of sediment, algae, and other substances will adhere to the surface of the cooling tower packing during operation. If not cleaned thoroughly, these dirt will be washed into the cooler in future operations, causing blockage of the heat exchange copper pipes inside the cooler and affecting the heat exchange effect. Therefore, it is necessary to thoroughly clean the cooling tower.

Option 2: Neutral cleaning without stopping the machine

Under normal operation of the unit, add neutral cleaning agent to the cooling water and chilled water system for a cycle of cleaning for about 30 days. Release the cleaning solution and add maintenance agent to complete the cleaning process. This solution takes a relatively long cleaning time, but it can be carried out under normal operating conditions of the unit without affecting its normal operation.

Characteristics of neutral cleaning agents:

1. Neutral cleaning without corrosion: This product does not change the pH value of the water after being added to the central air conditioning water system, and does not cause corrosion damage to metals. It completely solves the corrosion hazard of commonly used strong acidic cleaning agents on metals and achieves non corrosion cleaning.

2. High cleaning efficiency: It is effective for various types of scale, especially for insoluble scales such as sulfate and algae biofilm that cannot be cleaned by acid washing. The scale removal rate is above 95%, thus restoring the original performance of the equipment and maintaining its clean operation.


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3. Simple operation: Under normal startup conditions of the central air conditioning, add neutral cleaning agent to the water system and run for about 30 days to completely remove various scale in the water system.

Neutral cleaning principle:

According to the latest theory of coordination field chemistry, the d-orbitals of metal ions can split and form orbitals with different energies under the influence of the electrostatic field of certain coordination compound compounds. When the ligand gives a lone pair electron to form an O bond with the central metal element, if there are empty π molecular orbitals or empty p, d molecular orbitals in the coordination molecule, and the symmetry is appropriate, the lone pair on the d-orbitals of the central element can form feedback π bonds with the ligand, thereby forming stable coordination compounds.

Based on the above principles, compounds with π molecular orbitals that can cause energy level splitting of Ca2+and Mg2+d orbitals are selected as π acceptor ligands. When this compound interacts with calcium and magnesium scale, it forms stable coordination compounds with Ca2+and Mg2+d, thereby disrupting the molecular structure of calcium and magnesium scale. It is dissolved in water and removed by wastewater discharge


After all cleaning is completed, perform chemical maintenance on the cooling water and refrigerant water systems. Adding corrosion and scale inhibitors to the refrigerant water system can form stable complexes with various metal ions such as iron, copper, and zinc, preventing the corrosion of oxygen and metal ions in the water. Through chelation, inhibition, and lattice distortion. It can prevent the formation of scale salts in water. Thus playing a role in corrosion and scale inhibition. Adding bactericidal and algal agents to the cooling water can regulate water quality by inhibiting the production and survival of bacteria and algae during the circulation process, as the cooling water system is in an open state.











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