Catalytic cracking riser cooling gasoline
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Please discuss the necessity of the presence of gasoline for cooling in the riser of the catalytic cracking unit.
Since it is designed, it must be useful, but our factory does not use it, not only the quenching oil but also the quenching water. The blind plate is always blind. . .
It is still necessary to reduce secondary reactions, especially when processing heavy raw materials. Without a terminator, it is difficult to control the temperature.
I may not have made it clear. What I am talking about is the cooling gasoline in the riser, which is used to prevent the riser from overheating when the feed is cut off. I wonder if you use cooling gasoline when cutting off the feed?
Of course, this is necessary. If there is no secondary reaction, more secondary reactions will occur. Moreover, some refineries use waste oil as a terminator. If not, is it very wasteful? Quenching gasoline can also control the riser outlet temperature to prevent coking of the settler. It has its uses and should be used.
No cooling gasoline was used when cutting off the feed, and I personally think it is not necessary. As for the overtemperature at the riser outlet, just close the regeneration slide valve. I have indeed seen similar information. While reducing the fresh feed, the outlet of the riser is cooled by spraying gasoline. I don't know what the purpose is. In the past 18 years of dry catalysis, I have dealt with countless accidents, but this method has never been used.
This is a protective measure designed in early catalytic devices. The principle is that when the feed is cut off and the catalyst circulation volume does not decrease, by injecting gasoline, the gasoline quickly vaporizes and absorbs heat to prevent the upper and middle parts of the riser from overheating. I guess many factories won't use it, so no one pays attention to this measure. Because when cutting off the feed, instead of spraying gasoline to cool down, it is more convenient to reduce the catalyst circulation volume.
I haven't used it before. If it's overheated, just reduce the circulation volume.
I have never heard of this thing. Our device design does not have this line.
First sure gasoline as an end to the squeeze makes sense. The reason is that the temperature rises and falls, which is beneficial to temperature control. However, this cannot be used as a necessary means of adjustment. The addition of gasoline will increase the load on the subsequent distillation towers and air compressors.
I also think there is no need to inject quenching gasoline when the feed is cut off. Reducing the circulation volume can reduce the temperature. Isn’t it unnecessary to inject gasoline again?
As the original poster said, there is no need to use cooling gasoline. But it may be useful in another situation, such as when dealing with carbon accumulation. Although it is rare to hear of carbon accumulation accidents in catalytic cracking now!
The cooling gasoline line of the riser is necessary. The riser tube overheats too quickly, which is detrimental to the operation of the device. Using diesel as a terminator is still not as fast as gasoline, so I think it should be retained.
In my understanding, this is only available in old equipment. For example, our old catalytic equipment has it, but I heard the master said that it has never been used. I have been catalyzing for so long, and I have never seen it used. It is written in the operating procedures.: To prevent the temperature in the middle and upper part of the riser from being too high, you can spray cooling gasoline, but in reality, adjusting the regeneration slide valve is much faster and is not used at all.
The purpose of using the terminator is to increase the circulation amount of the catalyst and, more recently, the depth of the reaction. It is completely necessary and can be changed from gasoline to water.
There seems to be very little use of gasoline as cooling oil after cutting. After sudden material cutting, the temperature rises very quickly, but it is more straightforward to turn down the circulation volume. Using gasoline as a terminator has advantages and disadvantages, depending on the specific conditions of the device. For example, in the MIP process, gasoline is mostly used as a terminator to modify the gasoline to reduce the olefin content and increase the octane number.
Ours is not used. But there is such a process. Personally, I don’t think it’s necessary to use it.
Isn’t the purpose of injecting gasoline just to cool down? Isn’t it also the purpose of the terminator?
After cutting the feed, we control the over-temperature of the riser pipe and use accident steam or pre-lift steam without cooling the gasoline. We do not have such a design in our equipment.
What the poster means is that after the riser cuts off the feed, the feed can be resumed after a short period of processing. In order to prevent the overall temperature of the riser and settler from falling. It is not conducive to resuming the feed. Temporarily use cooling gasoline to ensure normal fluidization of the catalyst and stabilize the pressure difference between the two devices, so as to resume the feed as soon as possible. This is also the reason for the design of cooling gasoline. It can be said that in this case, cooling gasoline is very necessary. However, it is recommended not to consider it, and it can be completely replaced by a terminator.
When cutting off the feed, we generally use a terminator to cool down the gasoline. There is no separate cooling gasoline, right?