Methods for scale prevention and inhibition in circulating water heat exchangers

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For the heat exchangers in circulating water systems, in addition to manual cleaning during annual maintenance, the use of online physical methods for scale prevention can sometimes yield significant benefits in terms of energy savings and emission reduction. I. Types of scaling: Determining the type of scaling is the first step. Of course, for circulating water systems, the main type of scaling is calcium carbonate. There are also some exceptions; for example, in companies that use a large amount of acid, the scaling inside the heat exchangers may be calcium sulfate. In short, the cost of using calcium carbonate for online scale inhibition is much lower than that of calcium sulfate, which is more troublesome to use. II. Working Principle of Online Scale Prevention and Removal Equipment The working principle of online scale prevention and removal equipment, such as microwave-based systems for this purpose, relates to the structure of calcium carbonate. It takes advantage of the two different crystal forms of calcium carbonate; in the absence of external forces, calcium carbonate forms hard and dense calcite scales that are difficult to remove. However, if external forces such as microwaves are applied, the calcium carbonate crystals become less hard and dense, and tend to transform into aragonite crystals, which are more loose and easily washed away by water currents. Research shows that external forces such as microwaves can convert 80%-90% of the calcium carbonate precipitated as scale into aragonite form, which is the principle behind online scale inhibition. Of course, this mainly applies to calcium carbonate; it doesn’t work for calcium sulfate scaling. III. Equipment installation location: For online scale inhibition devices, there are generally two possible installation locations: 1. At the front end of the heat exchanger – installed at the inlet pipe of the heat exchanger, so that the microwave signals can cover the entire heat exchanger, thereby converting most of the calcium carbonate scale into soft aragonite crystals that can be washed away. 2. Pipes in the circulating water system: Another method is to install them on the pipes of the circulating water system; through the seed effect, this can help reduce scaling throughout the entire circulating water system. 3. Summary (WeChat: TigerPeng2014) The best approach is to install a set in the circulating water system to reduce scaling throughout the entire system. Additionally, another set can be installed separately on critical equipment, thereby providing dual protection.