Cooling Tower Cleaning Treatment Plan and Process

2025-03-05

The cooling tower is exposed to the outside for years, and the fan has a strong adsorbing force, allowing a large amount of sediment and dirt to enter the tower. After long-term operation, the cooling capacity of the cooling tower will gradually decrease. The water outlet holes of the water distributor are easily blocked, and the sediment and dirt are also likely to enter the cooling water system, which will directly affect the normal refrigeration of the cooling water system. In order to prevent the above situations from occurring, the cooling tower must be cleaned regularly.

Cooling Tower Cleaning Treatment Plan and Process
Plan 1: Cleaning during Shutdown
That is, according to the cleaning process: sterilization and algaecide cleaning — cleaning with scale remover — pre-filming — cleaning after cleaning. This plan requires cleaning when the equipment is shut down, and the cleaning time is about 8 days, with a scale removal rate of over 95%.
Cleaning Procedure: Water flushing — sterilization and algaecide cleaning — scale removal cleaning with cleaning agent — flushing after cleaning — pre-filming — cleaning after cleaning.

Water Flushing
The purpose of water flushing is to flush away loose dirt such as dust, sediment, shed algae, and corrosion products in the system with a large flow of water as much as possible, and at the same time, check the leakage situation of the system. The flow rate of the flushing water should be preferably greater than 0.15m/s. After the flushing is qualified, drain all the flushing water in the system.
Sterilization and Algaecide Cleaning
The purpose of sterilization and algaecide cleaning is to kill the microorganisms in the system and make the biological slime attached to the surface of the equipment peel off. After draining the flushing water, add a sterilization and algaecide agent to the system for cleaning, and stop the cleaning when the turbidity of the system tends to be balanced.
Scale Removal Cleaning with Cleaning Solution
The purpose of cleaning with the cleaning solution is to dissolve the scale and oxides in the system with the cleaning agent and then flush them away with water. Add the cleaning agent to the central air-conditioning system, and use a circulating pump for circulating cleaning. Empty at the highest point and discharge at the lowest point to avoid air resistance and blockage of the drain, which may affect the cleaning effect. During the cleaning process, regularly detect the concentration of the cleaning solution, the concentration of metal ions (Fe2+, Fe3+, Cu2+), temperature, pH value, etc. End the cleaning when the concentration of metal ions tends to be stable.
Rinsing after Cleaning
This water flushing is to flush away the residual cleaning solution and the removed impurities during the cleaning. During the flushing, keep opening the drain to flush away the impurities and residual liquid deposited in the short pipes. Continuously test the pH value and turbidity during the flushing, and end the flushing when the pH value and turbidity tend to be stable.
Pre-filming
The purpose of pre-filming is to form a complete 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 has been damaged.
Cleaning after the Cleaning is Completed
Cleaning of the Cooler and Evaporator: After the cleaning is completed, open the cooler and evaporator of the main unit. Use a special pipe cleaner to pull through and flush each pipe of the cooler one by one. Since the water circulation system of the cooler is exposed to the atmosphere and the heat exchange temperature is high, the scaling condition of the cooler will be more serious than that of other places. If necessary, connect an open circulating system externally to the cooler separately for scale removal cleaning to ensure that each copper pipe in the cooler is unobstructed. Flush the evaporator with high-pressure water to thoroughly flush away the precipitated impurities in the evaporator. If necessary, also connect a circulating system externally to the evaporator separately for cleaning.
Cleaning of the Cooling Tower: Since the cooling tower is exposed to the atmosphere, a large amount of sediment, algae, etc. will adhere to the surface of the cooling tower packing during operation. If not cleaned thoroughly, these dirt will be flushed into the cooler during subsequent operation, causing blockage of the heat exchange copper pipes in the cooler and affecting the heat exchange effect.
Therefore, the cooling tower must be thoroughly cleaned.

Plan 2: Neutral Cleaning without Shutdown
Add the neutral cleaning agent to the cooling water and chilled water systems for circulating cleaning for about 30 days while the unit is operating normally, then drain the cleaning solution, and add the maintenance agent to end the cleaning process. This plan has a relatively long cleaning time, but it can be carried out while the unit is operating normally and will not affect the normal operation of the unit.
Characteristics of the Neutral Cleaning Agent:

No Corrosion during Neutral Cleaning: After adding this product to the central air-conditioning water system, it does not change the pH value of the water and causes no corrosion damage to the metal. It completely solves the potential corrosion hazard of the currently commonly used strong acidic cleaning agents to the metal and realizes corrosion-free cleaning.
High Cleaning Efficiency: It is effective for various types of scale, especially for difficult-to-dissolve scales such as sulfates that cannot be completely removed by acid cleaning and biological slime of algae. The scale removal rate is over 95%, thus restoring the original performance of the equipment and keeping the equipment running cleanly.
Simple Operation: Under the normal operating condition of the central air-conditioning, add the neutral cleaning agent to the water system and run it for about 30 days, then drain the cleaning agent to completely remove various scales in the water system.
Principle of Neutral Cleaning:
According to the latest theory of coordination field chemistry, the d orbitals of metal ions can split under the influence of the electrostatic field of some coordination compound ligands to form orbitals with different energies. When the ligand donates a lone pair of electrons to form a σ bond with the central metal element, if there are empty π molecular orbitals or empty p, d molecular orbitals in the ligand molecule and the symmetry is appropriate, the lone pair of electrons on the d orbitals of the central element can form a feedback π bond with the ligand, thus forming a stable coordination compound.

Based on the above principle, select compounds that can cause the energy level splitting of the d orbitals of Ca2+ and Mg2+ and have π molecular orbitals as π accepting ligands. When these compounds act on the calcium and magnesium scales, they form stable coordination compounds with Ca2+ and Mg2+ on the d orbitals, thus destroying the molecular structure of the calcium and magnesium scales, dissolving them in water, and removing them through sewage discharge.
After all the maintenance cleaning is completed, use chemicals for maintenance of the cooling water and refrigerant water systems. Add a corrosion and scale inhibitor to the refrigerant water system, which can form stable complexes with various metal ions such as iron, copper, and zinc to prevent the corrosion of oxygen and metal ions in the water. Through chelation, inhibition, and lattice distortion effects, it can prevent the formation of scale salts in the water from forming scale, thus playing the role of corrosion and scale inhibition. Add a sterilization and algaecide agent to the cooling water. Since the cooling water system is in an open state, bacteria and algae will be generated during the recycling process. The sterilization and algaecide agent can inhibit the generation and survival of bacteria and algae, thus playing the role of adjusting the water quality.