What are the causes of blockage in the circulating hydrogen pipeline of a hydrogenation unit?
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In the hydrogenation unit’s circulating hydrogen pipelines, blockages tend to occur at the points where cold hydrogen is injected and at various hydrogen purging points, especially around control valves and manual valves. What are the main reasons for this? Operating condition: 19 MPa, temperature: 60°C. Last edited by caohaibin on 2009-2-19 19:01]
Ammonium salt deposition is caused by insufficient water injection; the amount of water injected should be increased.
Then why is there blockage at the hydrogen injection point and at the hydrogen purging point?
Main reasons: 1. Insufficient water injection, resulting in inadequate removal of ammonium salts； ⒉The new hydrogen has a high chlorine content ； ⒊The hydrogen sulfide level in the system is too high ； The above reasons cause ammonia salt blockage.
Because the crystallization temperature of ammonium salts is a bit lower.
I think there are two reasons. First, ammonia hydrosulfide tends to crystallize at low temperatures, and the temperatures of cold hydrogen and purge hydrogen are generally low. Second, both the pipelines for cold hydrogen and purge hydrogen are relatively thin with low flow rates, making crystallization more likely.
Because amine salts begin to form at temperatures below 170 degrees, increasing the water volume further has an impact on subsequent treatment and separation. Changing the water injection point to a position further forward could be considered the best option.
Two issues should be considered: 1. Whether the high-temperature level (i.e., after circulating hydrogen cooling) is set too high. 2. Check whether the water injection system is operating properly; consider changing the water injection point and increasing the water injection volume.
First, it is necessary to increase the water injection volume in order to wash away the ammonium salts； Secondly, the sulfur content in the recycled hydrogen is too high; desulfurization of the recycled hydrogen could be considered
It can be basically determined that it is caused by ammonium salt crystals; an analysis of the ammonia content in the recycled hydrogen can prove this.
What the original poster mentioned are all washed blind ends, where the temperature is low and they are not used frequently; therefore, ammonium salts tend to aggregate in these areas.
If it’s a newly installed device, it could also be due to rust and slag; we’ve encountered this issue with our devices, and even after blasting and cleaning, the problem persists!
Your operating conditions are 19 MPa and 60°C, which easily leads to the crystallization of ammonium salts. Analyze the ammonia content in the recycled hydrogen; if it is high, increase the water injection volume.
It’s just that the amount of water poured in is too little! Here, we had an incident too; just increasing the water supply resolved it! ~
Due to amine salts, insufficient water injection, and excessive ammonia in the circulating hydrogen.
Chlorides are also a possibility. . Caused by reformation hydrogen.
It might be sulfides; I’ve seen a lot of yellowish substance at the flanges on the pipelines that go from the furnace to the reactor. I’m just starting to work with hydrogenation processes, so I’d appreciate it if a professional could explain this to me
With the presence of chlorine, ammonium salt crystals precipitate in large quantities; it is sufficient to rinse them with softened water during maintenance
It sounds like you’re referring to the temperature at which crystallization occurs in an environment with water, at high exchange rates