Can steam injection at the bottom of the catalytic fractionation tower be discontinued? What are the impacts?
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Does stopping the stirring steam at the bottom of the distillation tower have an impact on operations and product quality?
The function of the stirring steam is to ensure a certain degree of turbulence in the oil slurry at the bottom of the tower, preventing the deposition of solid particles within the slurry; it also helps to reduce the partial pressure of oil and gas! It’s recommended not to stop!
Stirring steam, as the name implies, serves to stir. If the slurry remains at the bottom of the tower for a long time, it is prone to coking. Since this line was designed at the bottom of the tower, it must serve some purpose. It is highly recommended not to stop.
It cannot be shut down, otherwise solid particle deposition and coking will occur, the partial pressure of oil and gas will increase, which is not conducive to normal operation.
Whether coking occurs at the bottom of the distillation tower depends mainly on the bottom temperature and the amount of slurry discharged. The anti-coking effect of stirring steam is minimal; if scale inhibitors are also used, there is even less need to worry about coking. On the other hand, the fractionation tower operates with a fully gas-phase feed; it has only a distillation section and no stripping section. Unlike atmospheric towers, it does not require stripping steam to reduce the vapor pressure of the oil and gas. So, this stream of steam can be stopped. Keeping it results in increased steam consumption; on the other hand, when the temperature at the bottom of the tower is low after an emergency shutdown, it can easily lead to the pump for the oil slurry running dry.
There is slurry stirring at the bottom of the tower; is steam stirring still needed?
You decide for yourselves; our opinion is just for reference!
Saving energy and reducing consumption is a good thing, but it needs to be considered in its entirety! If the device operates for a long period of time, I’m willing to accept this level of energy consumption! Moreover, the situations you mentioned are rare cases!
I strongly advise against stopping, as the function of stirring the slurry and that of stirring with steam is the same – both serve to perturb the oil slurry at the bottom of the tower. However, in terms of design, the locations where the slurry is stirred and where steam is injected are different. Since the slurry is a highly concentrated liquid with high viscosity, it is not sufficient to rely on only one point for stirring the slurry； Secondly, have our colleagues considered whether, in the event of a disruption in the oil slurry supply, the stirring steam can still be injected normally to prevent excessive coking of the oil slurry? ； Thirdly, stirring steam can evaporate some of the lighter components in the oil slurry, thereby increasing the yield of the product. Overall, the advantages of using stirring steam outweigh the disadvantages
If there is a mixer for the slurry, it is usually not necessary to use steam for mixing. As for the impact on the oil-gas partial pressure, adjusting the various extraction temperatures will ensure that the product meets the required standards.
It can’t stop! The bottom temperature of the tower and the properties of the slurry determine whether coking occurs in the slurry system! Stirring steam is used to prevent coking at the bottom of the tower