How to carry out process handling for hot work inside low-temperature methanol washing absorption towers or hydrogen sulfide concentration towers during internal maintenance
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How to carry out process handling for hot work inside low-temperature methanol washing absorption towers or hydrogen sulfide concentration towers during internal maintenance
It’s not a processing technique! It is institutional guarantee! Once the management system is improved, just implement it!
Can work be started after the water flushing is complete? Neutralization washing is still required
In simple terms, the processing steps are: 1. Drain the liquid, 2. Purge with nitrogen, 3. Rinse with water, 4. Isolate with a blind flange, 5. Purge with air, 6. Analyze before performing hot work
Is no chemical cleaning required? Does nitrogen need to be supplied continuously?
Drainage, replacement and purging, as well as washing, must be thorough without any remaining corners to ensure compliance; the manholes should be opened for proper ventilation, and nitrogen must be completely removed to prevent suffocation.
This post was last edited by hekeshuen on 2020-9-4 at 14:16. In the presence of sulfur, ferrous sulfide is formed and adheres to the walls of the tower. Ferrous sulfide can catch fire easily when exposed to air, especially when it contains less than 30% moisture. This is an issue that requires special attention during the maintenance of many desulfurization towers; the situation is even more dangerous in low-temperature methanol washing processes that use high-sulfur coal, as well as in the desulfurization towers of some petrochemical plants. Therefore, it’s best to be cautious. Preventive measures such as pre-washing, chemical cleaning, and nitrogen purging should be taken; additionally, ventilation accelerates the oxidation of ferrous sulfide, and the shedding of oxide scale can clog the inlet filter of the pump.
No chemical cleaning is needed; during washing, water is circulated using pump pipes. When the water temperature rises, it acts like a hot wash, and all the ferrous substances are removed, haha. Nitrogen supply must be stopped for hot work inside the tower; safety comes first.
After isolation of the single tower, washing with water is necessary; however, this does not guarantee the complete removal of ferrous sulfide. During any work involving open flames, it is important to keep the temperature inside the tower from rising, in order to prevent ferrous sulfide from catching fire. The best way to do this is to direct a stream of water from the area where work is being carried out, allowing the water to flow out from the bottom
During the maintenance in July, we replaced the nitrogen gas in the drainage system; after flushing the drainage with water twice, the samples met the analysis requirements. We then used fans to ensure forced ventilation at the manhole, and after grinding the interior, the conditions for carrying out welding work were fully satisfied
Air must not enter the low-temperature methanol wash absorption tower!