How to control the circulating water system with frequent startup and shutdown?
After the system is started up, strengthen water quality analysis and conduct appropriate blowdown combined with turbidity and total iron data. Supplement corrosion and scale inhibitors according to total phosphorus data, and the concentration is recommended to be controlled at 1.5-2 times the normal concentration to slow down corrosion during the next shutdown. If the system has been running continuously for more than 48 hours, select non-oxidizing bactericides for sterilization according to temperature and microbial breeding conditions to prevent strong oxidative corrosion caused by unconsumed residual chlorine after adding oxidizing bactericides.
Operation sequence for water quality improvement after system leakage and plugging completion?
In case of a large amount of acid-base leakage, first adjust the pH of circulating water to neutral by adding sodium bicarbonate or sulfuric acid.
Conduct a large amount of replacement to reduce the total iron (<2), turbidity (<20) and COD (<150) of circulating water.
Carry out slime stripping or enhanced sterilization with non-oxidizing bactericides.
Increase the dosage of corrosion and scale inhibitors to 1.5-2 times the normal concentration for film repairing. Steps 3 and 4 can be operated simultaneously.
What are the causes of heat exchanger fouling? How to make a simple and rapid preliminary judgment?
Low flow rate, corrosion (mainly sediment and corrosion products, loose texture, red color); scaling (white or grayish white, relatively hard texture, a large number of bubbles generated when acid is added); zinc salt deposition caused by excessive addition of scale inhibitor (loose texture, grayish white appearance, dissolved in acid without bubbles).
Treatment measures for circulating water leakage?
Confirm the pollution source (makeup water quality, process medium leakage, microbial reproduction, etc.).
Targeted treatment measures: leak detection and plugging, enhanced replacement, enhanced sterilization, film repairing treatment.
Why are there black spots on the wall of the scale inhibitor dosing tank?
Chemical precipitation: Reverse osmosis scale inhibitors contain a variety of chemical components, and long-term standing may cause some components to precipitate on the tank wall and form black spots.
Microbial breeding: If the dosing tank is not used for a long time or not cleaned thoroughly, microbial breeding may occur, thus forming black spots on the tank wall.
Water quality problems: If the water source itself contains more impurities or microorganisms, black spots may also form on the tank wall during the dosing process.
Why is sulfuric acid selected for acid addition treatment of circulating water, while hydrochloric acid is generally used to adjust pH in reverse osmosis systems?
Concentrated sulfuric acid is generally used for circulating water instead of hydrochloric acid, mainly for cost considerations: sulfuric acid is cheap, and concentrated sulfuric acid does not corrode steel, which is convenient for transportation and storage; hydrochloric acid is not only expensive but also highly corrosive to steel, requiring anti-corrosion for the acid addition system. On the other hand, the use of hydrochloric acid will increase the chloride ion content in cooling water, and the enrichment of chloride ions is easy to aggravate pitting corrosion and perforation of equipment.
In reverse osmosis systems, sulfate ions introduced by sulfuric acid are easy to form calcium sulfate scale under the condition of high hardness and high alkalinity in the second stage of reverse osmosis, which is difficult to clean.
