Principle of nitrogen protection
Thread Content
The main substances inside the vacuum distillation vessel are those that can form explosive mixtures with air. How should one proceed in case the vent pipe of this distillation vessel loses its vacuum? If using nitrogen protection, how exactly is it carried out?
When the system was initially designed, nitrogen pipelines should have been provided for the distillation kettle and the tower top. When the system is shut down, the material extraction valve is first closed, and nitrogen can be introduced slowly from both the top of the tower and the distillation vessel to reduce the system’s vacuum level; generally, it takes about half an hour to break this vacuum.
Use nitrogen to displace the explosive gas multiple times
Do not turn off the vacuum; cool the distillation vessel, and only turn off the vacuum when the temperature has dropped to a certain level. Replace with nitrogen three times
Add a nitrogen pipeline before entering the vent main (equipped with a control valve), and use a pressure sensor to regulate the nitrogen flow rate. This will meet the requirements.
Our facility also requires nitrogen protection during parking and maintenance. It uses nitrogen cylinders, with a pressure reduction valve assembly installed on the outlet; two oxygen pressure gauges are used for measuring pressure, but there is no flow meter. Replace the gas cylinder when the pressure is below 0.5 MPa.
The nitrogen sealing device is primarily used to maintain a constant nitrogen pressure at the top of the container, thereby preventing the materials inside from oxidizing and ensuring the safety of the storage tank. The nitrogen sealing device consists of two main components: the ZZDQ rapid release valve and the ZZYP micro-pressure control valve. When the pressure inside the tank rises to the set pressure, the rapid relief valve opens instantly to release the excess pressure from the tank. When the pressure inside the tank drops, the micro-pressure control valve opens to fill the tank with nitrogen. The inlet pressure of the micro-pressure control valve must be below 0.1 Mpa. Since the pressure in the on-site nitrogen cylinders is relatively high, a DZYP-type pressure control valve was installed at the outlet of the nitrogen cylinders to reduce the pressure to below 0.1 Mpa. The inlet pressure of the ZZYP micro-pressure control valve is 0.1 Mpa, while the outlet pressure can be adjusted (between 5 and 20 Kpa); it is generally kept between 5 and 10 Kpa. The discharge pressure of the ZZDQ quick release valve can also be adjusted (5–15 Kpa), with a typical setting of 10–15 Kpa. Working principle: Nitrogen from the cylinder enters the system――the pressure is reduced to 0.1 Mpa using a DZYP type pressure regulator――it then passes through a ZZYP micro-pressure control valve, where the pressure is adjusted to 10 Kpa――after that, it enters the expansion tank――the pressure is released through a ZZDQ rapid release valve installed at the top of the container (with a release pressure set at 15 Kpa). When the pressure in the container reaches 15 Kpa, the pressure inside the container is instantly released to ensure its safety. The return pressure of the ZZDQ quick release valve is 10–12 Kpa.
The basic principle is to replace flammable gases with nitrogen
In our workshop, nitrogen is forced in from the top of the centrifuge and exits through an opening at the bottom; I think you could use this approach as a reference
Reply to 9# xudebing: I have also been concerned about static electricity during the centrifugation process. But specifically, how is nitrogen protection applied to the centrifuge in the factory? Is it better to just go with grounding?