Regarding reactors and distillation columns
Thread Content
I’m new here, so I have a few questions for the experts: ①. When starting up the catalytic reaction unit, before removing the blind flanges from the oil and gas pipelines, has oil been fed into the distillation tower? Before removing the blind flange, how does the circulation work in the fractionating tower if oil is flowing into it, and how does circulation take place if no oil is flowing in? (Just describe the general process, for example: The raw material comes in from the external unit, passes through the raw material buffer tank, then goes through several heat exchangers, before returning to the raw material tank via the emergency return line.) ") ②. Do the so-called three major cycles refer to external tower circulation or internal tower circulation? ③How can open-loop circulation, closed-loop circulation, external tower circulation, and internal tower circulation be explained?
The three main cycles are the top cycle, the middle section cycle, and the bottom of the tower cycle. The external cycle involves no flow into the tower; instead, it operates through a return line in the crude oil tank, similar to an open-loop cycle, and ultimately reaches the tank area, with the purpose of heating the pipelines and removing water. Internal and closed-loop cycles both take place within the system and do not return to the tank area; they are generally used for heating purposes. In our case, steam is introduced in reverse order through the slurry generator to achieve the desired temperature, after which the various seals and flanges are heated.
Take a look at these two posts: 1. When does the issue of external and internal circulation in catalytic cracking units arise during startup? http://bbs.hcbbs.com/thread-853666-1-1.html (Source: Haichuan Chemical Industry Forum) Circulation inside the distillation tower during startup http://bbs.hcbbs.com/thread-835198-1-1.html (Source: Haichuan Chemical Industry Forum)
Was oil fed into the fractionation tower before removing the oil-gas blind flange?
Under normal circumstances, the removal of the blind flange on the large oil and gas pipeline is used as the dividing point: before removal, the distillation system operates in external circulation, while after removal it operates in internal circulation! After the large blind plate is removed, the gaseous mixture resulting from the reaction will enter the distillation tower; the catalyst particles in this mixture need to be washed away using oil. It would not be appropriate if the distillation tower were still operating in external circulation mode at that time!
No oil should be introduced; it is necessary to wait until the blind flanges have been removed, all air has been expelled, and a vapor seal has been established, before changing the oil slurry circulation to one that operates within the tower.
Yeah, then great expert, could you help me figure out whether it’s better to remove the air/oil blind plate before dealing with the catalyst? Is it better to remove the fuel and oil blind flanges before installing the catalyst?
Bro, take some time to check out the Q&A on catalytic cracking technology! There’s a vast amount of knowledge waiting for you there:)