What to do if the catalytic processing volume is low?

Based on the information provided by the poster, it cannot be said that it’s a problem with the raw materials. The raw materials are relatively heavy, but it’s hard to say whether that is the reason why the processing volume cannot be increased. It is evident now that there is excessive coking and an excess of heat, but there are many reasons behind the high coke yield, and it is necessary to analyze these factors as a whole.

During operation: 1. Consider increasing the amount of steam used for atomization by the nozzles. 2. Replace some of the heavy oil cracking catalysts at the bottom of the tower. 3. Use quench oil as a terminator. 4. Increase the steam supply to the stripping section. If severe coking is detected in the lift pipe during shutdown, it is necessary to consider replacing the nozzles; the design of these nozzles should ensure that 10% of the steam is used for atomization

Firstly, according to the poster’s description, it is necessary to have professionals calculate the heat load of the external heat exchanger. The external heat exchanger in our company was recalculated; the design provided by the design institute was too small, so we increased its size by nearly half to meet the production requirements. Secondly, there are various reasons for the high density phase temperature. From a process perspective: 1) Excessively high reaction temperatures and inappropriate pressure differences between the different units, especially high pressure in the settler, can increase coking. 2) The use of inhibitors can reduce coking. 3) The preheating temperature of the feedstock and the efficiency of atomization have a significant impact on coking levels. 4) Choosing the right oil-to-catalyst ratio is important; high bed temperatures can lead to insufficient circulation, inadequate reactions, and excessive oil carried by the catalyst. 5) Adjusting the steam used for gas lifting – reducing the amount of material stored in the gas lifting section and increasing the amount of steam used, especially in the lower gas lifting section. 6) Selecting an appropriate method for reprocessing oil; reprocessed oil and slurry are important tools for regulating bed temperature and product distribution, and these methods can be discontinued when the bed temperature is too high. 7) Analyzing the properties of the feedstock oil and adjusting the mixing ratio; lower carbon residue should result in less coking, but some heavy oils with cyclic hydrocarbon structures are difficult to crack. From these perspectives, it is recommended that the poster adjust the operating parameters, introduce some regenerated catalysts to observe the effect on coking, and adjust the air flow. Address any issues related to abnormal bed structure and fluidization. From the perspective of equipment and catalysts: the quality of the nozzles directly affects the reaction efficiency; it is necessary to check whether the selection and installation of nozzles meet the standards. Alternatively, it might be possible to use new, highly efficient atomizing nozzles, such as CS nozzles. Additionally, the choice of catalyst is a very important factor; different oils require different catalysts. Some catalysts with low specific surface areas cannot provide sufficient pore sizes for the molecules in the feedstock oil or for large droplets that have not been properly atomized, resulting in poor reaction efficiency and higher bed temperatures. It is recommended that the poster ask several major catalyst manufacturers in China to recommend suitable catalysts, or seek out refineries with similar feedstock properties to obtain balancing agents for testing. Since the information provided by the poster is not very detailed, this is all I can suggest for now. If there are any misunderstandings or errors, please feel free to point them out so we can discuss them further

It’s a problem with the raw materials; the device has to turn into a “boiler” – just kidding.

Do you have coarse gasoline reprocessing nozzles at the feedstock nozzle area? If so, you can use some of them to see how the temperature distribution in the riser changes, and to determine whether it can have some effect! Increase the pre-raising steam volume to improve the catalyst flow pattern in the pre-raising section and see if that helps. Can we add more misting steam? What percentage of the feedstock volume does the total steam injection amount in the riser account for now?

It’s the MIP device, right? I saw you say the opposite. The inventory in the stripping section is a bit low; based on a catalyst-to-oil ratio of 6, with a catalyst circulation rate of 10 t/min and a residence time in the stripping section of 3 minutes, the inventory in this section is 30 tons. What is the reserve amount for the other two units? The preheating temperature can be increased and the reaction temperature reduced, which helps to minimize coking, but there may be more oil slurry. This reduces coking to increase the processing capacity. Confirm whether it is an MIP device.

Yes, my device is similar to the MIP process, but it lacks pipelines from the settler to the secondary reactor feedstock; in other words, the amount of material in the secondary reactor cannot be controlled manually, nor is there any gauge for measuring it.

Design institutes are still working on such designs these days. I have come across devices of this kind; they were designed in Luoyang, and the expansion section of the lift pipe was modified by adding components on their own. The hardware components of these devices are fine, and they operate well. What’s needed now is to find a designer who can meet the required conditions, including those related to the composition of the raw materials. If it doesn’t work after one attempt, then adjustments need to be made.

I wonder if increasing the pre-lift steam in the lift column, shortening the reaction time, lowering the reaction temperature, and reducing the catalyst circulation rate will be effective

The processing volume will definitely decrease! Because the basic nitrogen contained in coker wax oil is more easily adsorbed on the catalyst than hydrocarbon compounds, basic nitrogen has a significant impact on catalyst deactivation.

Increase the linear speed of the second reactor, reduce its residence time and catalyst load, decrease its depth of reaction, and minimize coking. There are steam nozzles near the second reverse inlet.

I would like to ask whether your facility is designed for 800,000 tons per year or 80 tons per hour, and what type of oil it is designed to process.

Is this “modified MIP” intended to avoid patents? It’s unlikely that the Luoyang Institute designed this! The catalyst reserve in the secondary reactor has a significant impact on coking. It’s understandable that there are no adjustment mechanisms in your design, but why aren’t there any measurement points built in? In this situation, to increase the residence time in the second reactor, one can only do so by increasing the processing volume or the amount of steam used. Since the temperature in the regenerator is already high, it seems that the only option is to add more steam in order to increase the linear velocity in the second reactor.

1. In the first reaction zone of the MIP series-connected riser reactor, primary cracking reactions take place at a high reaction intensity; after a short residence time, the mixture enters the lower part of the second reaction zone, which has an expanded diameter. This zone employs measures such as expansion, addition of fresh catalyst, and injection of cooling medium to reduce the flow rates of oil and gas as well as the catalyst, thereby lowering the reaction temperature in this zone and meeting the requirements regarding space-time yield. These measures aim to increase hydrogen transfer and isomerization reactions while controlling secondary cracking reactions to an appropriate level. 2. Is coker wax oil blended into the wax oil used in your facility? If so, consider reducing the amount of coker wax, with a maximum level of 15 wt%. 3. You may consider replacing the heavy oil catalyst; if a MIP-specific catalyst is currently being used and the olefin content in the gasoline is not high, this could be an option. 4. Adjust the amount of stripping steam appropriately. 5. If the properties of the feed oil remain unchanged over time, consider carrying out hydrogenation of the feed oil

We tried using stripping steam; increasing its amount didn’t result in any change in the regenerator temperature. We also tried increasing the amount of material in the stripping section, from 20 tons to 27 tons, but that didn’t work either. Ugh, I’m crying. . . :'(

It is possible to consider reducing the pressure in both devices, but there is a concern that too low an inlet pressure for the compressor could lead to surge. The current inlet pressure of the compressor is 0.035 MPa. Based on the experience of those who are more knowledgeable, what is the lowest inlet pressure at which surging can still be avoided?

Has the char formation rate been calculated? Calibrate it and take a look. Also, has the position of the feed nozzle changed? How long is the reverse reaction time? There is a problem with the design.

1) Improve raw materials； 2) Increase the heat removal load of the regenerator ； It would be best to redesign the reactor and use the genuine MIP instead

I think the preheating temperature of the raw material used by the poster is too low. For a raw material with a carbon residue level of 6.5 and a specific gravity of 0.93, the preheating temperature should be at least 220. Try increasing the preheating temperature and see what happens. Additionally, coker wax oil has a high content of basic nitrogen; when added in large quantities, it can cause the catalyst to become temporarily inactive, leading to an increase in coke formation. The amount added must also be uniform. It’s also worth considering whether the catalyst’s activity is too high – if the catalyst designed to reduce olefins has excessive activity, more coke will be produced.

Since the MIP section has differential pressure measurement points, it is possible to calculate the reserves of the two reverse layers.