Nitrogen sealing for hydrochloric acid tank
Thread Content
When reviewing the tank farm drawings, it was found that the ammonia tanks were equipped with nitrogen sealing; upon asking why, it was said that it was a strong recommendation from the owner. Open the internet, and there are countless discussions of all kinds. It was later found that the hydrochloric acid tank was also nitrogen-sealed. I’m completely baffled. According to HG/T20570.16-95, the purpose of using a nitrogen seal is to prevent the material inside the tank from being contaminated or reacting as a result of contact with air. SH3007-2014 4.2.10: Large tanks containing Class I, II, A, B, and A type internal media require nitrogen sealing. SH3047-93 \"Code for Occupational Safety and Health Design in Petrochemical Enterprises\": (Under normal circumstances) Installing a nitrogen blanket on storage tanks for flammable materials can prevent the formation of explosive gas mixtures in the gas space of the tanks. The dichloroethane storage tank is sealed with nitrogen to prevent dichloroethane from coming into contact with air and moisture, thereby avoiding an increase in its water content.
https://bbs.hcbbs.com/thread-1979399-1-1.html Floor 7: The safety requirements related to nitrogen sealing are, in essence, unrelated to environmental protection; nitrogen sealing merely keeps the gas phase in an inert state, reducing or essentially eliminating the oxygen content in that gas phase. Nitrogen sealing cannot prevent the volatilization of chemicals or reduce the saturated vapor concentration. However, in many places, the relevant authorities require the use of a nitrogen seal; generally, the system consists of an internal floating roof, a nitrogen seal, a vent valve, and an emergency release valve. Adopting this setup requires redesigning and rechecking the tank’s structure. The specific approach depends on the safety and environmental protection requirements as well as regulatory provisions set by the local authorities. I fully agree with this statement.
Ammonia water and hydrochloric acid are volatile and tend to escape; increasing the nitrogen seal raises the pressure in the gas phase, which reduces volatilization and helps maintain concentration stability to a certain extent
It might be a subjective desire to reduce the direct release of these odorous gases into the atmosphere; there’s no specific plan for that
This might be a requirement related to environmental protection.
The key is how to restore the vacuum inside the tank and where to send the excess gas. Just consider environmental protection and safety from these two aspects.
A nitrogen seal is a safety device; ammonia can be understood in this context – designs requiring fire and explosion protection are necessary when its concentration is ≥10%. In such cases, hydrochloric acid storage tanks no longer serve any practical purpose from a safety or environmental perspective. The vapor pressure of the material exists objectively, and generally, the vent openings for hydrochloric acid storage tanks are not located on the tank itself, but rather on environmental protection devices such as buffer tanks, water seal tanks, and spray towers. I remember that at that time, President An argued with Huan Si, stating that the nitrogen seal system he wanted to use was separate from the exhaust gas treatment device required by Huan Si; a nitrogen seal cannot replace exhaust gas treatment, whether using organic or inorganic media.
Original poster, may I ask what the concentration is for nitrogen-sealed ammonia storage tanks?
Their argument isn’t a big deal. . . The Tianjiayi incident – that famous case of gods fighting with each other – gave us all a lot to talk about
For hydrochloric acid tanks, there’s no need to install a nitrogen seal; a water seal tank is sufficient