Discussion on the main issues of catalytic cracking
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The operation of the catalytic cracking unit faces the following two main problems. The first problem is that the riser tube is coked, which affects the operating cycle. The second problem is the loss of catalyst. Each ton of catalyst is usually tens of thousands of yuan, and the cost of catalyst is dozens of tons. The loss is huge. If you have any tips in this regard, please reply and participate in the discussion.
1. Coking in the riser can be considered: 1. Improve the design and operation of the pre-lift to achieve dilute phase transportation, reduce the back-mixing of the catalyst, and ensure that the catalyst and raw materials are fully mixed. 2. To improve the atomization effect, choose a nozzle with better atomization effect and increase the atomization steam. 3. Try to increase the temperature of the feed section as much as possible, 4. Choose appropriate reaction conditions and temperature, 5. Increase the agent-oil ratio to convert more heavy hydrocarbons, increase the conversion rate, and reduce coking. 6. Fresh raw materials and recycled oil are fed separately to prevent the heavy components in the recycled oil that are difficult to crack from occupying the active center of the regenerant, reducing the activity of the catalyst and reducing coke generation. 7. During the start-up process, or after cutting off the feed, the nozzles must be opened symmetrically to prevent feed deviation. 8. Inject terminator into the riser tube to effectively control the secondary reaction and prevent coking. 9. If the air compressor is capable, dry gas pre-lifting technology can be used to reduce hydrothermal deactivation and thermal collapse of the catalyst to maintain the activity and stability of the catalyst and reduce coking. 10. Optimize raw materials and select low rare earth ultra-stable molecular sieve catalysts. two: There are many reasons for catalyst loss. 1. Laboratory analysis of the solid content of the oil slurry determines the effectiveness of the cyclone at the outlet of the riser. 2. What form of rebirth do you have? And what form of cyclone separator? 3. Smooth operation is critical.
Riser tube coking problem: 1. Clean up after shutdown, as old coke can easily cause coking. 2. Modify the nozzles and replace them with high-efficiency nozzles, using multiple symmetrical distributions. 3. Use dry gas instead of steam as pre-lift gas to passivate heavy metals and reduce coking. There are many reasons for catalyst loss, which can be eliminated and analyzed step by step. If only the regenerator is running out, a balancing agent can be used to replace the fresh agent to replenish the storage capacity and maintain production according to the efficiency without stopping the machine.