Why is stripping steam used in settlers? What is the impact of the stripping steam volume on catalyst circulation?

Stirring steam is used to displace the oil and gas carried within the catalyst particles and in their micropores, thereby reducing the loss of reaction products and the coking load on the regenerator. Since the stripping steam flows in the opposite direction to the catalyst, it poses a certain obstacle to the catalyst circulation rate; the amount of stripping steam has a significant impact on the driving force acting on the raw material inclined tubes as well as on the catalyst circulation rate.

The role of the stripping steam is as mentioned above; in my opinion, its impact on the catalyst circulation rate is virtually negligible. Since the catalyst circulation rate depends on the opening degree of the regeneration slide valve, if the plant in which the questioner is working is a traditional single lift tube plant, changing the catalyst circulation rate while keeping the regeneration temperature constant should be achieved by adjusting the temperature at the lift tube outlet. If the unit in which the poster is located has dual lift pipes, this can be achieved by adjusting the opening degrees of the regeneration slide valve, the self-circulation slide valve, and the relay pipe slide valve. The raw catalyst lift pipe/inclined tube is located below the stripping section, and catalyst flow is achieved through static pressure; therefore, the amount of stripping steam has a minimal impact on the fluidization of the catalyst within the raw catalyst lift pipe/inclined tube. In summary, the effect of stripping steam on the catalyst circulation rate is virtually negligible. The above is for reference only

Rebuttals and questions are part of my process of progress. Needless to say about its effect; just speaking of the dosage, it is indeed related to the catalyst circulation rate. The calculation data for catalyst circulation balance show that the dense-phase density in the settler (which can be equated to the material level) acts as a driving force for the green catalyst. When there is an excess of steam, the dense-phase bed becomes less dense, and the green catalyst tends to carry this excess steam with it as it moves downward. During the process in the inclined tubes, the steam carried within can cause problems, leading to issues in the green catalyst flow path. If this flow path is unstable, then there’s no need even to talk about the overall circulation volume.

Reply to 3# 498400160: I think the stripping steam has a significant impact on fluidization

By the way, is medium pressure better or is superheated low pressure better?

Reply to 4# zhouqxhpc: \"The dense-phase density of the settler (which can be converted into a material level) acts as the driving force for the catalyst to be used.\" What about the pressure difference between those two vessels? Isn’t that the main driving force?

Reply to 6# zhanghanaili: Low-pressure superheating is good and cost-effective. .

The stripping steam in the settler is used to strip the oil and gas from the raw catalyst, thereby reducing the amount of carbon that can be stripped; the quantity of this stripping steam is determined by the circulation rate of the catalyst.

As a supplementary point, the function of the stripping steam is to remove the oil present in the catalyst; when the stripping is effective, the oil content in the catalyst decreases, which facilitates its fluidization. To put it metaphorically, a catalyst mixed with mud will certainly not flow as well as a dry catalyst. I also heard an old plant manager say that carbon deposition on the surface of the regenerant facilitates fluidization, as the carbon deposit acts like a lubricant. The above views are provided for discussion only.