Analysis of corrosion causes of multi-purpose heat treatment furnace

Hot water boiler is the main heating source in recent years. Using hot water heating, the room temperature is suitable, has obvious coal saving effect than steam heating, so it is welcomed by heating users. However, through many years of work experience, it is found that the corrosion of some hot water boilers is very serious after shutdown, which deserves attention.

The corrosion causes of multi-purpose boiler manufacturers are as follows:

1. Do control the make-up water quantity. Article 100 of hot water boiler safety supervision regulation stipulates that "the leakage of hot water system is generally no more than 1% of the system water capacity". However, some units mistakenly think that with hot water boiler, it is convenient to use hot water. The hot water of the system is used for bathing, washing clothes so on. A 2.8MW hot water boiler makes up nearly 100 tons of water every day.

2. The "water quality standard of low pressure boiler" (hereinafter referred to as the standard) is seriously implemented. The standard clearly stipulates that when the water supply temperature is ≤ 95 ℃, the pH value of circulating water shall be controlled to reach 10-12, which is a very important index, but some units do implement it. However, these units pay more attention to the hardness of the make-up water. Some of them have specially installed the flow bed water treatment to meet the needs of the make-up softened water. They mistakenly supply the hot water boiler according to the water standard of the steam boiler, think that if the softened water is qualified, it will scale corrode.

3. Users whose heating network pipeline installation is unqualified circulating water cannot be delivered to the end of the system. Some users in order to be frozen, to increase the number of air emissions, drainage on the hot, do exhaust on the cold, resulting in increased leakage.

4. The constant pressure of expansion water tank is inconsistent with that of boiler. The expansion water tank of a unit is located on the fourth floor, its height is less than 15m, but the boiler constant pressure is 2.5kg/cm2. As a result, in order to maintain the working pressure index of 2.5kg/cm2, the stoker often replenishes the water, which overflows into the trench in an ambiguous way, which costs water coal.

5. Shutdown without maintenance. After the heating period, the boiler was shut down, the temporary workers were dismissed. Some boilers were filled with softened water, some were exposed to the atmosphere lacked necessary maintenance.

The above situation can clearly show that the corrosion of hot water boiler is caused by the lack of hot water heating knowledge of users, especially the most serious damage caused by a large amount of supplementary water, which only adds a large amount of dissolved oxygen, but also because of the large amount of supplementary water the overload operation of water treatment equipment, often in order to ensure the amount of supplementary water, the water with a very high chlorine content is added into the system, in the boiler water pH When the value is only 7-8, hydrogen ion, oxygen ion chloride ion are very active as corrosion medium. Due to the low pH value high concentration of hydrogen ions in boiler water, hydrogen will react with cathode under the corrosive substances of ulcer. When there is dissolved oxygen in the water, the presence of chloride will greatly increase the corrosion rate of iron. This is because the chloride ions in water are easily absorbed by the oxide film on the metal surface replace the oxygen ions in the oxide film, so as to form soluble chloride, destroy the oxide film, make heat treatment The metal surface of the furnace continued to be corroded. Based on the above analysis, it is concluded that excessive water supply to the hot water heating system is the key to the corrosion of the hot water boiler the reduction of its service life.

The above is the multi-purpose furnace production line to introduce the relevant content, I hope to help you.