Issues with circulating water and water quality

Water that contains salts such as calcium ions and magnesium ions, without any treatment, is called hard water. Water from which ions such as calcium and magnesium have been removed through treatment in a cation exchanger is called softened water. Water in which virtually all cations and anions have been removed through treatment with cation and anion exchangers is called deionized water.

I agree with what was said on the 2nd floor: during the cooling process of heat exchangers, desalinated water is the most commonly used substance to prevent scaling and corrosion. Desalinated water is employed in our air separation unit’s water cooling towers as well.

But isn’t the demineralized water too acidic, and does it cause equipment corrosion?

Deionized water is not acidic; softened water will suffice in most cases, with the concentration ratio usually being controlled. The circulating water is ordinary fresh water; it is best to apply anti-corrosion treatment to the heat exchangers, and the currently popular technique for this purpose is nickel-phosphorus plating. Our diesel hydrogenation heat exchangers, which use H2S and oil as the working media, have proven to be effective; there are no issues with water at all

Demineralized water refers to water from which the vast majority of cations and anions have been removed. This type of water is also classified into several grades, and the specific differences in water quality among these grades can be found in relevant standards. As the name implies, softened water is water from which the hardness (i.e., ions such as calcium and magnesium) has been removed; these two types of water are used in different applications. For cooling water, if the cooling system is a closed-loop system with minimal water loss, desalinated water is recommended ； If the cooling system is to be in contact with the atmosphere, there is significant water loss; it is therefore recommended to use circulating cooling water (that is, to use water once and then add appropriate agents for corrosion inhibition, scale prevention, as well as sterilization and algae control), as this is more economical. Under normal circumstances, the cost of desalinated water is 5 to 10 times that of circulating cooling water.

Our company had to stop operations due to water problems

To save costs, circulating water is generally used for cooling; depending on the specific circumstances, the pipes are descaled at regular intervals using dilute acid along with corrosion inhibitors