Problem of poor discharge under the three spinners in the catalytic cracking unit
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The flue gas from the catalytic device regeneration passes through the three-spinner; below this device, it goes through four elbows. Some of this gas enters the critical flow velocity nozzle, while another portion goes into the four-spinner. At the bottom of the four-spinner, some of the flue gas is directed to the critical flow velocity nozzle, and another part goes into the waste catalyst storage tank. Currently, the pipeline from the three-spinner storage tank to the critical flow velocity nozzle is hot, but the temperature of the pipelines leading from the four-spinner to the waste catalyst storage tank is lower. Moreover, the waste catalyst storage tank does not contain the catalyst powder separated by the three-spinner, which results in a large amount of catalyst powder in the flue gas flowing toward the chimney. I would like to ask if anyone has encountered a similar situation and how it was handled. Everything was normal during the initial operation, but abnormalities were detected about a month after the maintenance work was completed.
Use an F wrench to gently tap on the feed pipeline......:L
1. From the poster’s description, the critical nozzle line for the three-spin discharge route is in parallel with that of the four-spin route； In the four-spin rear route, the critical nozzle line is used for pressure balance, ensuring that the flow in the four spins remains unobstructed. 2. When balance flap valves are installed in the feed legs where the four spins enter the waste material pipeline, interruptions in flow can occur due to the intermittent operation of these flap valves, and this is something that happens quite frequently. The measures taken by the friend on the second floor are also common and effective methods. 3. In the flue gas flow process described by the poster, the interruption of the four-turn flow is mainly due to insufficient pressure drops upstream and downstream of the four-turn element; as a result, the driving force of the flue gas passing through it is low. Over time, the moisture in the flue gas condenses, causing the catalyst to clog and blocking the material inlet of the four-turn element. 4. Methods such as tapping the four rotating material legs, opening the agent transfer port of the waste agent tank to increase the pressure difference across the four rotors can all be tried. Additionally, if the opening of the critical nozzle is too small, pressure builds up along the critical line, resulting in insufficient flow from the four-spin outlet to that critical line; this is also a factor that can cause the flow in the four-spin system to be interrupted. 5. The flow process at the three-spin dust discharge outlet is quite simple, and there are limited possible causes, so these can be analyzed one by one and corresponding measures taken. Detect and address it early; don’t wait until the catalyst has solidified, as that will make things more complicated
Calculating the vapor volume at the four-rotor discharge outlet: typically, this vapor volume is about 3% higher than the total flue gas volume. It’s very likely that the pipeline became cold due to catalyst caking after steam condensed following the shutdown of the plant. I remember seeing a similar post on this forum, along with a hand-drawn diagram included in it.
What form does the triple spin take? Have similar problems occurred before?
Was the critical nozzle checked during the shutdown? Could it be that wear of the critical nozzle is causing the flue gas to bypass directly into the chimney?
There was significant catalyst loss at the beginning of operation; it is estimated that the system became clogged right at the start
The critical flow velocity nozzle was just taken a look at; moreover, the lining next to it was severely worn, so only the lining was repaired
The situation you mentioned does indeed occur quite often in reality, and it really needs to be taken seriously!