About dirt
Thread Content
The students would like to ask the seniors a few simple questions: 1. How does dirt form? 2. How can heat exchanger design minimize generation? 3. What other methods are there for dealing with the dirt that forms, besides chemical and manual methods? 4. What is the cleaning cycle for dirt? How often should it be cleaned, and how long does each cleaning take? 5. Next, for a given heat exchanger, should cleaning be scheduled based on experience or through calculations? I hope the experts will be kind enough to share their insights. Thank you! This post was last edited by xkz1999 on 2009-4-16 13:24.]
The main methods for anti-scaling treatment include acidification, softening, carbonization, chemical treatment, and magnetization. (1) The acidification method involves adding sulfuric acid to convert carbonate hardness into non-carbonate hardness. Used in circulating water systems with high carbonate hardness. (2) Softening methods involve using chemical or physicochemical techniques to reduce or remove calcium and magnesium ions from water, such as lime softening, lime-soda softening, and ion exchange methods. (3) The carbonation method involves introducing carbon dioxide flue gas to suppress the decomposition of bicarbonates. (4) The chemical method involves adding scale inhibitors to water; through a complexing action, calcium carbonate is kept suspended in the water, preventing the formation of scale. Scale inhibitors are divided into ； Natural scale inhibitors, such as lignin, cellulose, starch, alginates, etc ； Inorganic scale inhibitors, such as polyphosphates, sodium hexametaphosphate, etc ； Organic scale inhibitors, such as sodium polyacrylate, organic phosphates, sulfonated polystyrene, polysuccinic acid, etc. (5) The magnetization method involves using a magnetic field to cause calcium and magnesium salt crystals to form loose, easily flaking scale. The main methods to prevent dirt include: (1) installing a side filter in the circulating water system, from which a portion of the circulating water is regularly drawn out and filtered through the side filter to remove suspended particles from the water ； (2) Use bactericides and algicides to control the growth of algae and microorganisms ； (3) On the surfaces of cooling towers and other equipment, methods such as applying anti-fouling paint or metal protective films are used to prevent the formation of biological fouling. The main methods to prevent corrosion are controlling the pH of water and adding corrosion inhibitors. The function of a corrosion inhibitor is to form a protective film on the metal surface that isolates it from the surrounding environment and blocks the corrosion current. Commonly used are: (1) Buffers that form a passivation film include chromates, cuprates, molybdates, nitrites, etc. (2) Corrosion inhibitors that form a precipitative film include polyphosphates, organic phosphites, silicates, zinc salts, ferrocyanides, etc ； (3) Corrosion inhibitors that form adsorption films include amines, thioethers, lignins, etc. In actual use, two or more corrosion inhibitors are typically employed to enhance the corrosion inhibition efficiency. This post was last edited by jia717 on 2009-4-16 18:35.]
There are many forums discussing dirt; the original poster can take a look at http://bbs.hcbbs.com/search.php?searchid=2173&orderby=lastpost&ascdesc=desc&searchsubmit=yes&page=1. This post was last edited by ybbhiu on 2009-4-16 at 13:25.]
Dirt formation is generally caused by the precipitation of salts in the cooling water when the heat exchanger is at high temperatures, as well as by the growth of algae; additionally, some materials are not clean to begin with. The best way to control dirt in the cooling water is to prevent its temperature from rising too high