Central air conditioning water system cleaning method, process and case
When the central air-conditioning circulating water system runs for a long time, some salt deposits, corrosive debris, and biological sludge are often produced in the system. These substances will affect the heat transfer efficiency of the heat exchanger of the unit, and regular treatment of the air conditioning circulating water system can improve the heat exchange efficiency; reduce operating energy consumption; avoid high-pressure alarms and high-pressure protection failures; reduce maintenance costs; and extend the service life of equipment.
There are several cleaning methods. Common physical and chemical cleaning are recommended by the Refrigeration Encyclopedia public account. For slight scaling, it is recommended to use physical cleaning, but for end temperature difference ≥5℃ or copper pipe scaling of more than 3mm, it is recommended to use chemical After cleaning, or even chemical cleaning, it can be processed physically.
1. Physical cleaning:
Physical cleaning mainly uses the scouring effect of water or the brushing, wiping, and scraping effects of appliances to remove deposits in equipment and pipelines. The main methods of physical cleaning are: high-pressure water cleaning and appliance cleaning.
①High-pressure water cleaning: High-pressure water cleaning is a method that uses a powerful jet of high-speed water to act on the surface to be cleaned at a certain angle. It is usually used for cleaning the inside and outside of the heat exchanger tube bundle and the cleaning of cooling tower packing, but this effect is limited.
Central air conditioning water system cleaning method, process and case
When the central air-conditioning circulating water system runs for a long time, some salt deposits, corrosive debris, and biological sludge are often produced in the system. These substances will affect the heat transfer efficiency of the heat exchanger of the unit, and regular treatment of the air conditioning circulating water system can improve the heat exchange efficiency; reduce operating energy consumption; avoid high-pressure alarms and high-pressure protection failures; reduce maintenance costs; and extend the service life of equipment.
There are several cleaning methods. Common physical and chemical cleaning are recommended by the Refrigeration Encyclopedia public account. For slight scaling, it is recommended to use physical cleaning, but for end temperature difference ≥5℃ or copper pipe scaling of more than 3mm, it is recommended to use chemical After cleaning, or even chemical cleaning, it can be processed physically.
1. Physical cleaning:
Physical cleaning mainly uses the scouring effect of water or the brushing, wiping, and scraping effects of appliances to remove deposits in equipment and pipelines. The main methods of physical cleaning are: high-pressure water cleaning and appliance cleaning.
①High-pressure water cleaning: High-pressure water cleaning is a method that uses a powerful jet of high-speed water to act on the surface to be cleaned at a certain angle. It is usually used for cleaning the inside and outside of the heat exchanger tube bundle and the cleaning of cooling tower packing, but this effect is limited.
②Appliance cleaning: the method of cleaning the system pipelines with cleaning tools such as brushes or gun guns. Usually used for cleaning inside heat exchanger tubes.
2. Chemical cleaning:
The chemical cleaning method is a cleaning method that dissolves, loosens, falls off or peels off the deposits in the equipment and pipelines to be cleaned through the chemical action of chemicals. Generally speaking, chemical cleaning methods can not only remove the dirt in the system, but also remove various scales, metal corrosion products and biological slime. The chemical cleaning method is suitable for vertical and horizontal shell and tube condensers.
1. Connect the water pump: connect the water pipe to the circulating water pump, pay attention to the direction of the water inlet and outlet of the water pump, and ensure that the circulating water in the shell tube is "downward in and upward out". The water pump connection pipe interface can be selected at the pressure gauge, thermometer, sewage pipe, etc., or it can be self-opening.
2. Sludge stripping: Calculate the circulating water volume, calculate the dosage based on the circulating water volume, add the sludge stripping agent at the ratio of 600~800g to 1 ton of water (take Kangxing brand as an example), turn on the water pump to circulate for 4 hours, Clean up the suspended solids stripped off in time during the cycle.
3. Descaling: Detect the pH value of the circulating water before adding the descaling agent (Caerxikang) to compare the changes of the pH value before and after cleaning; according to the circulating water volume, add the descaling agent at a ratio of 1:10 to 1:20 to prevent The descaling agent reacts too fast to block the system. The descaling agent can be added in 3~4 intervals of 20min; circulate for 4~8 hours. Pay attention to the pH value of the circulating cleaning fluid during the circulation process. If the detected pH reaches about 4~5, It turns red after adding a small amount of descaling agent again, indicating that it is clean.
4. Rinse: After the main washing and descaling, wash the shell and tube with clean water repeatedly until the rinse is close to neutral (ph=6.5±0.5) and the circulating water is clear.
5. Pre-film passivation (also after booting): Before pre-filming, ensure that the water system is cleaned thoroughly, add pre-filming agent according to the circulating water volume, add 1L of pre-filming agent A and pre-filming agent B according to 1 ton of water, Put in multiple times. During the dosing process, the ph needs to be detected, and the ph value is controlled at 6.5±0.5 by the dosage.
6. Cleaning acceptance: After the cleaning is completed, start up and run. After the unit load is loaded to more than 80% and run for two hours, check the temperature difference between the corresponding shell and tube ends. If the end temperature difference is not higher than 2°C, the cleaning effect is good.
Note that cleaning operators must be professional maintenance personnel, and improper cleaning may damage the equipment. Finally, we look at two cases:
Case 1: An electronics factory uses a certain brand of centrifuges and screw machines, and uses acidic cleaning agents in the maintenance process. The copper pipes are corroded due to the excessively high ratio and the system is flooded, which brings huge economic losses to the factory.
Case 2: A certain brand of screw compressor was used in a subway project, and the heat exchange tube was cleaned due to improper use of cleaning agents, which caused almost all the copper tubes to corrode and the system was flooded.
