What are the procedures for cleaning a circulating water system?

1. First, it is necessary to understand the main components of water scale. If carbonates are the dominant component, industrial sulfuric acid with a corrosion inhibitor can be used ； If silicate scale is present, some sodium fluoride can be added to sulfuric acid, or an acid-base alternation method can be used for cleaning. If there is a large amount of sludge, a sludge dispersant should be added. 2. During the cleaning process, try to avoid adding water; maintain the pH of the circulating water. If the pH exceeds the upper limit, add acid in appropriate amounts. During the cleaning process, pH, hardness, turbidity, and total iron must be continuously monitored. When hardness and turbidity no longer increase, the end of the cleaning process can be basically determined. 3. After cleaning is complete, replacement should be carried out as soon as possible. Once the turbidity is below 10 and the total iron content is below 1, it can be put into normal operation.

1.1 Clean the newly installed circulating water system to remove grease from inside the new pipes as well as any rust that formed during the system’s construction； After cleaning is complete, a pre-coating is applied to the entire system, forming a protective layer on the pipes and heat exchangers to prevent corrosion and lay the foundation for the proper operation of the system. 1.2 Cleaning steps: A. Check that all mechanical equipment is functioning properly, and remove any dirt, debris, and other waste from the collection tank. B. Install a filter screen with about 18 mesh at the water inlet (before the circulation pump) to prevent wood and plastic debris from entering the pipes. C. Fill the collection tank with clean water and circulate it to flush out as much sediment as possible from the system pipes, then empty and clean the bottom of the tank. D. Inject clean water, hang in the bypass the old test specimen, add a pretreatment cleaner at a concentration of 1000 ppm (based on the minimum retained water volume), and circulate for about 48 hours; stop the cleaning process once the effect on the test specimen before and after cleaning is evident. E. Since a large amount of foam is generated during cleaning, the defoamer must be added in separate batches, at a dosage of approximately 100 kg. F. After cleaning is complete, replace the water in the system until the turbidity of the water drops to 20PPM. Approximately 48 hours of displacement.

Acid washing - water rinsing - pre-coating - water rinsing