What is the required temperature of the regenerator bed when injecting fuel into the lift pipe during the startup of the catalytic unit?
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What is the required temperature of the regenerator bed when injecting fuel into the lift pipe during the startup of the catalytic unit? Previously, the operating procedures for our unit specified a temperature of 600–650°C; now, those procedures require 500°C. Meanwhile, the \"Technical Q&A on Catalytic Cracking Units\" states that the regeneration temperature should be no less than 560°C. Please discuss what criteria were used to determine this temperature Why are they different? And the difference is so big? What are the hazards of too low a regeneration temperature? Thank you.
Fuel injection is prone to coking, and the catalyst circulation is unstable; therefore, it’s better to set it at a relatively high value, around 660–680 degrees. It should not be below 640; otherwise, it can also cause coking. Of course, at this time, the burning oil supply needs to be adjusted promptly.
Here, we still use the temperature at the exit of the lift pipe as a reference; it is usually around 520°C, and the corresponding regeneration temperature should be around 650°C! The temperature difference is quite large; I guess the oil used for operation varies from place to place? The temperature of the raw materials used alone with wax oil or directly mixed with residue oil must be different, right?
Both current and past units use heavy oil catalysis.
The bed temperature we require is on the high side; otherwise, carbon buildup is likely to occur after fuel injection.
Yes, it’s better to have a slightly higher temperature when injecting fuel; only sometimes it’s not possible to raise the temperature, or it’s difficult to do so, in which case the temperature stays low. When it’s low, it doesn’t matter if the photocatalyst has a bit of oil on it, as the amount is small anyway.