The role of nitrogen supplementation in the reflux tank of Luchi low-temperature methanol wash
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Dear sea friends, in the Luchi low-iodine process, there is a nitrogen supply line connected to the heat regeneration slurry return tank, equipped with a self-acting control valve. The function of this wire is to prevent a vacuum pressure from forming in the reflux system. But under what circumstances could such a thing be possible? And can manufacturers of self-acting control valves handle negative pressure behind the valve?
The reflux system is directly connected to the thermal regeneration tower. The operating temperature of the thermal regeneration tower is approximately 100°C. So after parking, if the temperature of the thermal regeneration tower drops rapidly, its pressure may fall below atmospheric pressure. If the pressure in the thermal regeneration tower is below atmospheric pressure, then the pressure in the reflux system will also become negative accordingly. To prevent this from happening, a supplementary nitrogen pipeline has been installed.
Has this occurred during startup and normal operation?
Such extreme situations occur very rarely. Nothing like that has happened at my site in over 3 years. But since it has been added in the design, there should be relevant precedents.
It is rarely used in general. It is mainly used for pressure restoration. Prevent the tower pressure from dropping too low. :)
The main issue is not knowing under what conditions the tower pressure will drop too low, to the point where a vacuum is created.
If the vehicle is stopped under normal operating conditions, and the pressure is maintained after stopping (at around 2 bar gauge pressure). So even when cooled from over 100 degrees to room temperature, the tower pressure should still remain at around 1 bar gauge pressure. In an extreme case, if pressure is not maintained after parking (that is, the tower pressure is slightly positive), and then the tower cools down from over 100°C, negative pressure will occur; of course, this constitutes an operational error.
May I ask if the original poster ended up purchasing a self-acting control valve for negative pressure after the valve for the construction? We are facing the same problem in our design now.
In the end, this self-acting control valve was purchased based on the data provided by the patent holder
It is supposed to prevent the pump from pumping too quickly, which could lead to a large amount of methanol flowing out and creating a negative pressure