Analysis of the causes of severe coking in the gas collection chamber

1. The catalytic cracking feed contains a high amount of sludge oil, has a heavy distillate composition, and the mixing temperature of the feed and regenerator is low enough to prevent complete gasification; as a result, part of the feed remains in liquid form, which facilitates the formation of liquid coke； 2. The use of inefficient atomization nozzles results in insufficient vapor atomization, leading to the formation of large liquid droplets ； The improper placement of the nozzles results in uneven feed distribution ； 3. The temperatures on the inner surfaces of the equipment in the reactive sedimentation system and on the inner walls of the oil and gas pipelines are low, falling below the dew point of the oil and gas, which leads to their condensation and coking ； 4. The rapid separation system of the settler was poorly designed; as a result, oil and gas stayed in the settler for too long, undergoing secondary cracking, which led to extensive coking within the system ； 5. High oil and gas partial pressures increase the tendency to form coke ； 6. There are frequent unit accidents, continuous start-ups and shutdowns, as well as repeated interruptions in feed supply, which exacerbates coking in the unit ； 7. Severe coking occurs when the temperature at the outlet of the lift pipe remains too low for an extended period, or when the temperature in the settler does not reach its peak value during startup.

1. The catalytic cracking feed contains a high amount of sludge oil, has a heavy distillate composition, and the mixing temperature of the feed and regenerator is low enough to prevent complete gasification; as a result, part of the feed remains in liquid form, which facilitates the formation of liquid coke； 2. The use of inefficient atomization nozzles results in insufficient vapor atomization, leading to the formation of large liquid droplets ； The improper placement of the nozzles results in uneven feed distribution ； 3. The temperatures on the inner surfaces of the equipment in the reactive sedimentation system and on the inner walls of the oil and gas pipelines are low, falling below the dew point of the oil and gas, which leads to their condensation and coking ； 4. The rapid separation system of the settler was poorly designed; as a result, oil and gas stayed in the settler for too long, undergoing secondary cracking, which led to extensive coking within the system ； 5. High oil and gas partial pressures increase the tendency to form coke ； 6. There are frequent unit accidents, continuous start-ups and shutdowns, as well as repeated interruptions in feed supply, which exacerbates coking in the unit ； 7. Severe coking occurs when the temperature at the outlet of the lift pipe remains too low for an extended period, or when the temperature in the settler does not reach its peak value during startup.

Is the reaction temperature well controlled? Did the reaction temperature fluctuate by 2 degrees, both positive and negative?

They are all fixed-focus; it’s very troublesome to clean the focus when shutting down

1. Address the properties of the raw materials at the source, minimize residual carbon as much as possible, and use high-quality raw materials for processing； 2. It is essential to ensure a stable feed rate in order to maintain the line speed ； 3. Control an appropriate atomization ratio ； 3. Control the appropriate reaction temperature ； 4. Reduce the residence time of oil and gas in the settler and collection chamber ； 5. Increase the amount of anti-coking steam injected into the settler.

To what extent is coking severe in the gas collection chamber? Coking is a problem that exists in every catalytic unit