What should be considered when starting up the catalytic fractionation unit? How to establish a three-path cycle quickly?
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On March 21, a power outage of 20 hours occurred due to grid maintenance. Urgent repairs were also needed at the fractionation unit, as there was severe leakage from the reactions, resulting in a high solid content. All the valves in the slurry system were leaking and had to be replaced (this was due to the poor quality of the materials used, which were all carbon steel). The slurry system also required cleaning. Three-way circulation for the discharge of slurry; line cleaning. This is also a newly installed device, and the production team does not have much experience with it. I heard from those who work there that they use it to clean the crude oil tanks as well. When work started, an external circulation system for the tower was to be established, as well as a three-way circulation system; however, it wasn’t possible to set this up. The raw material pump and the slurry pump couldn’t operate at full capacity. It happened to be our shift, and we had a very busy night – the raw material tanks were drained of water, but it still seemed that there was water present in the raw material. How to quickly increase the flow rate of the pump, and what preparations should be made.
I think there are a few points to note: 1. The valves in the slurry system should preferably remain fully open; only control valves should be used for throttling； 2. Is the inability of the feed pump and slurry pump to achieve proper flow rate due to damage to the pumps caused by high solid content? If the solid content is very high, it is best to wash the slurry system with water before shutting down, and then clean it out. 3. When drawing in oil again, the circulation time for the open-loop route (to the tank area) should be longer; the main purpose is to remove water and ensure no dead corners remain. 4. Dehydration during the heating phase is particularly important; otherwise, it will lead to serious problems.
It is not easy to increase the flow rate in the slurry system; first, maintenance work involves cleaning the large oil and gas pipelines, the bottom of the distillation tower, and the coke deposits inside the slurry pumps. When the crude oil is circulated at startup, ensure that the crude oil has low water content