The role of nitrogen in cold pumps with low methane levels
Thread Content
What is the role of nitrogen at the seal of the cold pump, and where does the nitrogen go in the end?
Nitrogen is used for the mechanical seal; it can only be a series-type mechanical seal, with a flushing scheme using 53A or 53B. In a series-type mechanical seal, an outer set of seals is used to prevent the medium from leaking through, so the pressure there must be higher than that in the seal chamber – around 0.4 MPa. Therefore, the pressure of the sealing fluid is equal to the pressure in the seal chamber plus an additional 0.2 to 0.5 MPa. This pressure is provided by nitrogen. Nitrogen is used because it is an inert gas. The sealing fluid is usually white oil, and if air were used, the presence of oxygen in it would lead to oxidation. Nitrogen is pressed inside the tank, so it can’t go anywhere~ Generally, this approach is used for toxic substances. You can check if there is a tank attached to the pump.
The nitrogen purge effect, combined with the cooling caused by the leak, leads to freezing at the atmospheric side, which damages the mechanical seal; nitrogen carries away the cold medium that has leaked out