The catalyst with carbon deposits is easier to fluidize than the regenerator
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In a catalytic cracking unit, when starting up the catalyst, oil should be injected as quickly as possible once this is successful; some people say that catalysts with carbon deposits are easier to fluidize than regenerated catalysts. I don’t understand why the catalyst with carbon deposits is easier to fluidize than the regenerator ? ? ? ?
When starting the catalyst conversion, spraying fuel as quickly as possible is intended to raise the temperature of the catalyst. If no fuel is injected, the catalyst circulation relies on main air or stripping steam, which can lead to poor fluidization. This has nothing to do with the good fluidization of the soot catalyst.
That’s nonsense. . . Catalysts with carbon deposits have a high packing density and large particles, making it easy for such deposits to accumulate; they are also not easily removed from the settler and regenerator. . . Fresh catalysts, especially those that have been regenerated, come in many different varieties; their density may not be very high. As a result, during the fluidization process, it is easy for the catalyst to escape, making it difficult to locate it. . . The process of building up reserves is just slower. . . I do not advocate using catalysts that have not been fully regenerated for fluidization experiments. . . It’s better to use a balance agent. . . Once the fluidization goes wrong, it’s not that bothersome either. . . Haha. . . :lol
The packing density of the catalyst with carbon deposits is higher than that of the regenerant; how can it be easier to fluidize?
Due to carbon deposition, the friction coefficient between catalysts decreases, which facilitates fluidization – especially in the regeneration circuit. Excessive carbon deposition is detrimental to the regenerator and the sedimentator’s centrifugal separation mechanism; the increase in particles leads to a rise in the concentration at the inlet of the cyclone, thereby increasing the risk of product loss
I agree that \"catalysts with carbon deposits are easier to fluidize than regenerated catalysts,\" but there is a condition: it shouldn’t be severe carbon deposition; it’s similar to the idea that \"balanced catalysts are easier to fluidize than fresh catalysts.\" What I’m trying to say is that catalysts with some carbon present are easier to fluidize than those without any carbon~~~
This theory is incorrect; it simply means that when burning oil is used for fluidization, it’s inevitable that the bed temperature becomes difficult to control, resulting in poor fluidization and large fluctuations. Moreover, catalysts usually have balancing agents used at the time of startup, and prolonged exposure to steam heat can also lead to poor fluidization of the catalyst, which is normal
"Is it related to the two stages of stripping steam in the settler that a catalyst with carbon deposits is easier to fluidize than a regenerated catalyst?
Haven’t heard of it; I’m really curious too. What should I ask?
Indeed, that’s the case with our plant’s DCC model of 1.4 million tons. It was indeed difficult to fluidize before fuel injection, but after the injection, fluidization returned to normal quickly.
I agree with what was said above; it’s the same situation here when we start working – it becomes fluidized very easily after spraying oil, but I don’t know why
It can be said that the raw slurry is more stable during transport in inclined tubes compared to regenerated slurry; one reason for this is the high density in the stripping section, which results in less gas being carried into the inclined tubes； On the other hand, it is believed that the green slurry may contain a small amount of carbon powder, acting in a similar manner to a \"lubricant\". After fuel injection, the circulation rate of the inclined-tube catalyst also increased; unlike during the fluidization phase of the two reactors, the valve opening was small. These are some of the reasons for these phenomena. However, it is true that the inclined-tube transportation in the two units becomes more stable after fuel injection, compared to the fluidization phase of the two units.
The green slurry may contain a small amount of carbon powder, which functions in a way similar to \"lubrication\", and there is some logic to that. I think it might be related to whether the oil and gas, after injection, occupy the space in the settler I just don’t know why?
It is true that catalysts with carbon deposits are easier to fluidize than regenerated catalysts; catalysts with carbon deposits have a higher bulk density, larger particles, and larger gaps, which results in better flow properties. Fresh catalysts, especially those that have been well regenerated, have finer particles, a higher density, and smaller gaps, leading to poorer flow properties. I work in catalytic cracking; I have supervised start-ups and shutdowns, and I have personal experience in this area.