I would like to ask whether nitrogen purging is required for the methanol pipeline
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Here, after methanol is unloaded at the loading/unloading platform, it is transported to the storage tanks via pipelines. The distance between the platform and the storage tanks is considerable. I would like to ask if, after the methanol has been unloaded, it is necessary to use nitrogen to displace the air from the pipelines connecting the unloading nozzles to the pumps, as well as from the pipelines connecting the pumps to the storage tanks; or if it is necessary to empty the pumps so that all the material in those pipelines can be transferred into the storage tanks Note: The unloading pump is a positive-displacement pump that can transport gas-liquid mixtures; it is located at the loading dock, at a considerable distance from the storage tank. I’m not majoring in this field; I was forced to do it, haha. I know nothing about it – I’m quite inexperienced. Please don’t laugh at me. Thank you all here~~
I spent hours searching online; some sources said that the air level should be below 0.5%, while others claimed that nitrogen displacement isn’t necessary. I can’t figure it out, and all the information I found referred to storage tanks, not pipelines. It’s really confusing~~ By the way, thanks to the moderator for the points~~
To prevent an explosion, it should be replaced.
It should not be necessary; it’s best to explain the purpose of the replacement – what problems do you want to prevent?
We don’t perform any replacement, and shielded pumps are used, so it’s not possible to evacuate the volume
This is a relatively simple question, and it shows that the original poster has thought things through carefully. No replacement is necessary, as each tank truck has an open opening when loading; it’s not a sealed space, so even if there is some air present, it will flow into the tank truck.
There is no need for replacement in the short term; however, it is advisable to replace it if not used for a long time, as this can prevent corrosion of the pipes. It is also dangerous to have both ends of a pipeline filled with methanol sealed; it is better to keep one end connected to the system, or to purge it with nitrogen after use.
We use swing rotor pumps here, which are positive displacement pumps capable of transporting liquid along with gas. There is a distance of about 10 meters between the pump and the transfer hose, and the pipeline over this distance is buried underground. After unloading, liquid remains in that pipeline; to empty it, the pump is used to draw out the liquid from the buried pipeline. However, there is a concern that air might be pumped into the pipeline, which would be unsafe. To address this, nitrogen is used – after unloading, the ball valve on the side of the transfer hose is closed while the ball valve for nitrogen is opened, thereby using nitrogen to protect the process of drawing out the liquid.
Things are fine on our end; we use a positive displacement pump, which can be run empty
The methanol here is unloaded, so we are concerned that residual methanol and air remaining in the pipes could pose a safety risk.
Well, we were also concerned about the risk of air in the pipes used for storing liquid. Once again, thank you to everyone who replied to offer help ** and to the moderators who took the time to rate – thanks to all for your generous assistance!
To prevent explosions, nitrogen must be used for displacement
We usually don’t replace them here; replacement is necessary only if they aren’t used for a long time.
We use shielded pumps there; I don’t think they’re necessary. However, there are also nitrogen pipelines connected to our pipelines.
There is no need for replacement in a short period of time; however, replacement is necessary if the tube is left in place for an extended period to prevent corrosion
There is no need for displacement; it’s fine to use nitrogen for displacement as well.
The pipeline mentioned by the original poster does not need to be replaced; there is no problem with it, as we are not concerned about methanol oxidizing, nor about it catching fire or exploding, unless an external source of ignition is introduced. If it needs to be repaired, it must be replaced