Catalytic cracking degassing tank
Thread Content
Our unit (repeatedly emphasized: two-stage overlapping regeneration) has never had a degassing tank; I’m not sure if it’s useful now. In what situations is it used, and what are the effects?
Deaeration tanks were used in our previous coaxial post-coking tank process for catalytic units; they are also known as catalyst buffer tanks. Under normal operation, the storage volume is kept at 3–5 tons. If there are fluctuations in operation or in reaction pressure, this has a significant impact on the storage capacity of thedeaeration tanks, making it easy for them to become empty, which in turn increases the complexity of operation due to the additional need for level control. So I think this current process (two-stage overlapping regeneration) is relatively easy to control and advanced.
Our system features two stages of regeneration with the three units arranged side by side at different heights; there is a degassing tank between the second regeneration stage and the settler. Under normal conditions, the material level is always at 100%, so no control of the material level is necessary. In the event of fluidization problems, the degassing tank acts as an additional safety layer – even if the material levels in the first and second regeneration stages drop, it doesn’t matter as long as the degassing tank still has sufficient material, which prevents air from entering the lift pipe and causing serious accidents.
My system features two regeneration stages; at the outlet of the second regeneration stage, there is a degassing tank at the inlet of the regeneration riser. The purpose of this tank is to remove the flue gas carried by the regenerating agent. The removed flue gas returns to the second regeneration stage via the top of the degassing tank, thereby ensuring a more stable flow state of the regenerated catalyst within the riser.
The degassing tank is located after the regeneration stage, and there is sufficient space available. A inclined tube connects the regeneration stage to the degassing tank; air is blown in through this inclined tube and enters the degassing tank as well. The degassing tank is divided into a dilute-phase and a dense-phase section. Gas enters the regenerator, while the catalyst flows downward along vertical tubes. Below these vertical tubes are control valves that regulate the amount of material flowing into the lift pipes. By monitoring the pressure difference before and after these valves as well as changes in the density within the degassing tank, it is possible to assess the operating conditions of the vertical tubes. That’s an overview of the degassing tank.