The reason why the steel shell of pyrite acid boiling furnace is severely corroded (slurry feeding)
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Please speak enthusiastically, everyone, the boss of sulfuric acid
After cooling, fuming sulfuric acid is equivalent to dilute sulfuric acid and is highly corrosive.
It may be because the steel shell has been in a low-temperature environment for a long time, and condensed acid is generated, causing corrosion. Or there are too many stops, and more condensed acid is produced, causing corrosion.
The construction of the furnace is the key. If the construction quality of the refractory brick lining of the furnace is not good at the beginning (specialized furnace construction personnel, use of qualified refractory materials, strict control of ash joints of 2mm, and drying before starting the furnace), there will be cracks in the furnace lining, and the furnace gas will penetrate into the vicinity of the outer shell to form condensed acid, causing corrosion. If the operation is not good, the more times it is stopped, the greater the damage will be to the furnace lining, and the more serious the corrosion will be. The weather in the north is cold and the north wind prevails, so the corrosion on the north side of the open-air furnace is more serious.
The owner's furnace must be more than 6 years old, right? The reason has already been answered by other people.
Mainly caused by condensation acid corrosion, the way to prevent it is to increase the surface temperature of the steel shell. You can adopt insulation methods and wrap the entire boiling furnace, which can effectively solve this problem. This is proven in practice.
The oven after the furnace masonry is completed is also important. It is necessary to formulate an oven system and oven curve that meets the requirements to ensure that free water, adsorbed water and crystal water in the furnace and furnace bricks are removed. At the same time, the quartz in the refractory materials also undergoes crystalline transformation and is accompanied by changes in volume. The quality of the oven must be ensured through processes such as heating, constant temperature, re-heating, constant temperature, and cooling.
The corrosion of the shell of the roasting furnace is mainly due to the fact that some details during the construction process are not handled well, such as the seams of the water tank and the seams of the unloading port. After the furnace is lit, the temperature rises and the furnace gas enters and contacts the outer iron plate to form condensation acid. If the furnace is opened and stopped during normal operation, the accumulation of condensed acid formed will increase and cause corrosion. After the corrosion reaches a certain level, it can come into contact with the air, which accelerates the rate of corrosion and increases the area of damage to the roasting furnace.
In actual production and use of boiling furnaces, the service life of different manufacturers varies greatly. It has everything to do with furnace design, construction, and use!
Condensed acid corrosion, it is recommended that the furnace shell be insulated. You need to calculate the insulation thickness. It won’t work if it’s too thick. Control the shell temperature to be above 280 degrees.
The main reason for the corrosion of furnace steel shell is: There is a place where flue gas leaks in the furnace body. The leaked flue gas forms condensed acid between the insulation bricks and the steel shell and then corrodes the steel shell. Finally, the steel shell is corroded into holes or flakes and falls off. The measures taken are: During overhaul, the annular joints and expansion joints of the bricks in the furnace should be reinforced and sealed. The measures of insulation outside the furnace play a certain role but only treat the symptoms but not the root cause. The main function of insulation is to prevent excessive heat loss in the furnace (should be less than 5% of the total heat release), which will cause difficulty in thermal balance and ultimately lead to abnormal boiling in the furnace.