Regarding the shutdown of the atmospheric and vacuum distillation unit for pressure reduction and transition to circulation mode
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Dear seniors and experts, has anyone organized or is aware of the measures to be taken for the vacuum system after a vacuum distillation unit shutdown cycle? After shutting down the atmospheric and vacuum distillation unit and switching to circulation mode, I would like to achieve circulation in the vacuum side streams and the middle section. How can this be done? I’d like to hear everyone’s opinions and suggestions. Is it possible to achieve this through the start-up gas oil? How is the balance maintained? Thank you all for your valuable feedback
Just shut it down after purging the side line; why recycle it?
It’s the simplest and most direct method for purging; it’s straightforward, but I think it’s not a very sophisticated approach. If there are better methods and ideas, why not use one’s brain and learn through communication?
It depends on the structure of the accumulator tank in the depressure tower and the amount of oil added to the first atmospheric distillation stage. A recycling process is feasible; however, if too much diesel component is added, it can cause problems during startup
That’s what I think: by reducing it to one stage, the diesel component won’t solidify, and it doesn’t matter whether it circulates or not; it just needs to be kept in the pipeline. The streams from stage 2, stage 3, and stage 4 of distillation are combined to form mixed wax oil, which is then sent via the wax oil transfer line to the reboilers in stages 1 and 2. Then the oil flows from the tower to the Stage 2, Stage 3, and Stage 4 stripping towers, thereby enabling a shutdown cycle. What do you all think? Are there any suggestions?
Think carefully about the purpose of stopping operation; unnecessary cycles only increase energy consumption
Makes sense. Who would cycle if they had to shut down or undergo maintenance for a long time? Distillation and vacuum distillation technologies have been developed for many years now; everyone should come up with more innovative ideas and broaden their thinking. The processes involved in these units are complex, so it’s important to make full use of them to maximize their value.
Everyone is welcome to join the discussion. I’ve already tried out certain procedures, ideas, adjustments, and operations. If you’d like to know more about any specific aspect, feel free to leave a comment or send me a private message. Let’s discuss together the development direction and upgrades for atmospheric and vacuum distillation
When the furnace temperature is maintained at 250°C during pressure reduction and shutdown, the temperature at the outlet of the vacuum furnace should be kept at 300°C; the vacuum must not be disrupted. In cases like the third and second reduction stages, the oil becomes less dense, allowing for easier replacement, with the fluid then being sent back for recycling
What you’re trying to do is to extract the components between jet fuel and wax oil through vacuum distillation, using a vacuum side stream to produce diesel. It is possible to find out what the distillation temperature at 300°C under vacuum conditions corresponds to in terms of distillation temperature under normal pressure. By controlling so as not to remove the reduced distillate, it is possible to achieve the purpose of cleaning diesel in a reduced-pressure system. Another type of unit that typically has a return line for off-take is the fuel oil-type atmospheric and vacuum distillation unit or the chemical-type atmospheric and vacuum distillation unit; generally, lubricant-type atmospheric and vacuum distillation units do not have a return line designed for off-take.
Plugging the oil leakage holes in the oil collection tank will achieve this