Maintenance of high-pressure equipment in hydrorefining units
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Our company is planning to carry out maintenance on the hydrogenation refining unit. I would like to ask how high-pressure equipment should be maintained – how are hydrogenation reactors and high-pressure heat exchangers inspected?
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Items to be checked in the hydrogenation reactor: 1. Whether the thermocouples are in good condition. 2. Whether the high-pressure gaskets on the head are damaged. 3. Inspection of the lining inside the tower and the head. 4. Whether there is any blockage in the liquid distributor at the top of the tower, and whether the screw bolts are intact. 5. Whether the bolts securing the catalyst frame are in good condition, and whether the glass fiber sealing filler against the inner wall needs to be replaced. 6. Removing the catalyst frame for inspection: checking the performance of the catalyst, whether the screens are damaged, inspecting and replacing the ceramic balls, and determining whether the support grids are deformed and need repair. 7. The degree of corrosion and wear at various connection points, as well as any signs of blockage, etc. The above information is provided for reference only and may not be accurate.
Maintenance disassembly and assembly: When carrying out maintenance disassembly and assembly, the maintenance procedures for hydrogen exchangers with Ω-ring sealing structures must be strictly followed. Since the medium in the hydrogenation unit contains sulfides, during startup and shutdown, the residual sulfides react with water or oxygen to form polythiic acids. Therefore, alkaline cleaning must be carried out before cutting the Ω ring; after alkaline cleaning, the surface should not be washed with water, but rather dried with compressed air so that an alkaline film remains on the surface. If the reactor is not unloaded, the reaction residues flow through the Ω ring during the airtightness test. Therefore, it is necessary to prevent the hot air inside the Ω ring from cooling and condensing into water, which could create a polyoxysulfate stress corrosion environment. The preventive measure is to leave a 5–10 mm un-welded area at the very bottom when assembling the Ω ring; after the rest of the Ω ring has been welded, wait for some time so that the air inside the Ω ring cavity cools to room temperature before welding the reserved section, thereby preventing the air from condensing into water. During the airtightness test, the bottom of the Ω ring is heated using a steam belt until the test is completed, raising its temperature above 100 ℃ to vaporize the water in the chamber, thereby preventing the formation of polythionic acid. The Ω ring can be removed and replaced after being cut multiple times.