Prevention of scale

To prevent the boiler from forming scale or operating with thin layers of scale, it is necessary to improve the treatment of water supplied to the boiler; this is an important factor in ensuring the safe and efficient operation of the boiler. To prevent scale formation, the following methods are commonly used: 1. External water treatment for the boiler. This method is applicable to various types of boilers. At present, the reliable method for external water treatment is the lime+soda ash softening process, which involves adding an appropriate amount of quicklime and soda ash to the already clarified water to achieve softening. The lime-soda softening method has two types: cold and hot. The cold method is carried out at room temperature to reduce the residual hardness in water to 1.5–2 milliequivalents per liter. The thermal method involves heating the water temperature to 20–80°C to reduce the residual hardness in the water to 0.3–0.4 milliequivalents per liter. Therefore, the thermal method should be used as much as possible to improve the softening effect. The ion exchange softening method relies primarily on the exchange resin in sodium ion exchangers for softening. Due to its strong adsorption capacity, the exchange resin can absorb calcium and magnesium ions present in water, thereby bringing the hardness of the boiler feedwater to acceptable levels. Ion exchangers are divided into two categories: inorganic and organic. Inorganic exchange resins can only undergo surface exchange, resulting in poor softening effects, and are therefore used less frequently. Organic exchange resins are characterized by a loose core structure of their particles, allowing the exchange reaction to take place both on the surface and within the particles; they offer good softening effects, which is why they are widely used. 　　2. Water treatment in the pot. This method involves adding chemicals to the boiler water, which react with the calcium and magnesium salts that cause scaling in the water to form loose sediments. These sediments are then removed from the boiler through drainage, thereby preventing (or reducing) scaling in the boiler. Chemical water treatment inside the furnace is generally used in small, low-pressure fire-tube boilers. Common chemicals used for water treatment in boilers include trisodium phosphate, sodium carbonate (soda ash), sodium hydroxide (caustic soda), and organic colloids such as tannin. When adding chemicals, various drugs should first be prepared into solutions before being added to the boiler. Typically, the solution concentration of trisodium phosphate is 5–8%, the concentration of sodium carbonate is no more than 5%, and the concentration of sodium hydroxide is no more than 1–2%. There are two methods of dosing: periodic dosing and continuous dosing. Regular dosing is mainly carried out using a dosing tank ； Continuous dosing involves adding the chemical continuously to the water supply in front of the water supply equipment. For steam boilers, it is best to use a continuous dosing method, as this helps maintain a uniform concentration of chemicals inside the boiler. In cases where water treatment is carried out inside the boiler, it is necessary to enhance the boiler’s blowdown process in order to remove the sludge and scale that have formed, thereby achieving better results.

This post was last edited by dongjiang1001 on 2011-8-9 08:49. By controlling the basic parameters of the boiler water, such as pH value, phosphate content, and hardness, it is possible to reduce the formation of scale.

This post was last edited by dongjiang1001 on 2011-8-13 at 17:14. Ensure proper control of the quality of demineralized water and the operation of the deaerator; add scale inhibitors in accordance with regulations, and maintain proper monitoring of the quality of boiler water.

An electronic descaling device can be installed! Of course, industrial boilers must be equipped with water softening devices (as required by the boiler inspection authority).

Boiler descaling device, descaler, ultrasonic descaling apparatus

Online automatic scale prevention, descaling, and corrosion protection – available technologies in Germany

I heard that a Genenbili magnetic product can keep the system running flawlessly; it’s worth giving it a thought!