Operational precautions for the pure oxygen pipeline in Shell’s powder coal gasification unit
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Dear colleagues, the safe operation of pure oxygen pipelines is extremely important for gasification units. Please use your wisdom and actively discuss the issues related to the safe operation of pure oxygen pipelines in Shell’s powder gasification units, with a focus on the precautions that need to be taken when operating such pipelines!
The operating requirements for pure oxygen pipelines are extremely strict; in my opinion, attention should be paid to the following aspects: 1. Low-activity low-carbon steel should be used as the material； 2. The welding quality must be smooth to avoid any unevenness ； 3. Thorough degreasing is required, including connected steam and nitrogen pipelines, valves, instruments, bypasses, etc ； 4. Graphite cannot be used for gaskets and valve seals ； 5. The valves must meet strict sealing requirements; the switching time should be short, and the sealing must be tight to prevent both internal and external leaks ； 6. Purge thoroughly before use ； 7. The stamping process should be slow to prevent excessive flow rates.
What was said upstairs was very detailed; in fact, some regulations regarding the cleaning of oxygen pipelines have also been established in China, and discussions on this topic have taken place within our region as well. In practical operation, nitrogen is used for purging before introducing oxygen, followed by venting of oxygen, then pressure equalization via a bypass line, and finally oxygen is introduced through the main line. However, it was found that the purging methods used by Texaco and SHELL are not quite the same; Texaco skips the pressure equalization step and directly uses nitrogen for purging during stamping.
Excuse me, Haiyou on the 2nd floor: I have doubts regarding point 4, as we didn’t mention such a requirement when manufacturing oxygen valves. It is only specified that the graphite must be ultra-pure, that it should be molded in one piece without any joints, and that measures must be taken to prevent delamination, along with obtaining TA-LUFT certification. Please give some advice.