It can also be protected by ammonia or nitrogen, the preparation is as dry as desiccant. Because ammonia is lighter than air, when use ammonia to protect, ammonia should be injected from the upper part and air discharged from the bottom. The same to nitrogen. In order to prevent air leakage, the pressure of 0.3-0.5 Mpa should be maintained, and ammonia or nitrogen should be supplemented in time when the pressure decreases.
Maintenance Basic Principles of Industrial Boiler
1. Prevent the entry of air mix into the boiler and steam water system.
2. Keep the metal surface in the steam water system dry.
3. Form a corrosion resistant film on the inner surface of the metal to isolate the air.
4. Immerse the metal surface in a medium containing deoxidizer or other protective medium.
In order to prevent or mitigate the corrosion, protective measures should be adopted. There are many ways to stop furnace protection, which can be divided into two main categories: wet protection and dry protection. Wet protection is usually used in a short time, for example, within a month. The common method of wet protection is to keep the pressure between 0.3 and 0.5 Mpa to prevent air leakage by filling the boiler with deoxidized water or aqueous solution containing alkali. If the boiler need to shutdown for a long time, or the whether is cold, dry protection should be used to prevent the equipment from freezing. The method is that when the water temperature drops to 70 ~ 80 C after stopping boiler, all the boiler water is discharged, the water in the heating surface is evaporated and dried by the waste heat of the boiler, and the water vapor is blown out by compressed air. After that place a container containing anhydrous calcium chloride in the drum. Calcium chloride is added in the ratio of 0.5 to 1.0L per cubic meter of water volume (2 kg/m3 for quicklime). Then the manhole is closed and checked regularly, when the desiccant is powdered replace it by new.