What are the methods for cleaning boiler scale

Scale is a major problem that bothers our lives, especially many young people who are often busy with work and do not pay attention to the cleanliness of their homes. They often find that scale in cups, kettles, and water heaters will accumulate more and more. Severe cases will cause cracks and many adverse reactions, which will also have adverse effects on us. Removal of scale is very important to us. So what are the methods for cleaning boiler scale?

1. Manual descaling: manual scraping and scrubbing.

2. Mechanical descaling: Use a professional pipe cleaning machine.

3. Chemical descaling:

1/. Alkali boiling descaling, the chemicals in the alkali boiling mixture are sodium hydroxide, sodium carbonate and trisodium phosphate. The ratio concentration is 0.3-0.5% sodium hydroxide + 0.5-1% trisodium phosphate (the amount of sodium carbonate is 2-3 times that of trisodium phosphate). Slowly increase the pressure to half of the rated pressure, maintain a high water level and boil for 24-48 hours, then drain the alkaline liquid after boiling. Rinse with clean water until the pH value of the water is less than 9.

2/. Pickling and descaling. It must be carried out by a professional and qualified unit.

Before pickling the boiler, the mud and scale in the boiler must be thoroughly rinsed, the thickness and area of ​​the scale layer must be checked, the corrosion of the furnace tube must be checked, and the scale samples must be analyzed to determine the dosing method. Generally, carbonate scale and phosphate scale can be cleaned with hydrochloric acid, and some silicate scale must be cleaned with hydrofluoric acid. During cleaning, a certain amount of corrosion inhibitor must be added to the acid solution to reduce corrosion to the boiler steel plate.

Acid pickling is mainly used to remove carbonate scale. The principle is to use highly corrosive hydrochloric acid or nitric acid to react with carbonate to generate soluble salts and release CO2 to achieve the purpose of descaling:

In order to prevent acid from corroding the metal, corrosion inhibitors are added during the pickling process to slow down the corrosion of the metal and control the corrosion rate below 6g/m2.h. However, pickling can only remove carbonate scale, and has little effect on insoluble scale such as sulfate, silicate and phosphate. The discharge of pickling waste liquid will cause serious environmental pollution.

Since improper pickling technology can cause serious corrosion damage to the boiler or even make it scrapped, the state stipulates that operators engaged in pickling must undergo rigorous technical training and obtain a qualification certificate issued by the provincial technical supervision department before they can engage in pickling.

Cleaning boiler scale is very critical. First of all, we must undergo professional training because boilers are like other supplies stores. Boilers are very dangerous. If they are not cleaned properly and cracks occur, it will increase casualties. Therefore, we need professional training on boiler cleaning. Note that because the boiler is made of metal, it cannot be placed together with a lot of things.