Did the catalyst startup heating settler catch fire?

1# bingfeng1203: This kind of situation has occurred in our company; on two occasions, combustion took place in the oil and gas collection chamber at the top of the settler, with temperatures exceeding 800°C, and on one occasion, combustion of coke occurred inside the settler, with temperatures reaching extremely high levels. The reason for this is that combustion in the collection chamber occurs because: 1) the coking is not thoroughly removed, leading to combustion as the temperature rises ； 2) During operation, the temperature at the reverse outlet of the pipe is low; as the heavier components condense, they penetrate into the lining layer, and upon heating they evaporate, gather together, and then burn ； Settler combustion is incomplete combustion of coke ； Solution: 1) Thoroughly remove the coke (this is necessary) ； 2) The heating process should be carried out slowly; it is best to keep the vent fully open at the initial stage in order to remove the evaporated gases from the equipment ； 3) Once a combustion occurs, cut off the main air supply, use steam to disperse the oil and gas, and then ignite and raise the temperature – combustion will not occur again. The above are merely personal opinions; I hope colleagues in this field will engage in more exchanges! (jeewang@163.com)

Under normal conditions, the ignition point of semi-coke is around 450 degrees Celsius; the exact value for coke used in catalytic cracking is not well known. However, if a sudden and rapid increase in temperature inside the settler is detected, it can be inferred that coke is burning. Under normal circumstances, if the temperature is already very high, the system can be cooled using steam, while simultaneously controlling the volume of air entering the settler; this should be the main method of regulation. If there is an excess amount of coke in the settler, it is necessary to reduce the air flow in order to control the temperature slowly; if there isn’t much coke, steam can be introduced to control the temperature and ensure the safety of the equipment. Also, I’m very curious to know what happens after a combustion occurs in your case?

I’ve learned that there are also such situations.

I know that one plant ran into trouble – its centrifuge got damaged. The main air supply should be cut off, and the reactor should be purged with steam. Additionally, if the coke clumps are not clean, they may cause debris to fall off during startup and block the feed legs of the centrifuge. It’s best to open the device narrowly and take a look.

I don’t think it’s necessary to cut off the main air flow, stop the regenerative catalyst circulation, increase the amount of stripping steam and anti-coking steam, control the temperature; after everything has been burned completely, we can proceed further

Thank you for the correction; it should be to turn off the standby and regeneration cut-off functions

When heating the two vessels, do not raise the temperature too high; 320° is sufficient for the settler. Once fluidization occurs in both vessels, then increase the temperature gradually.

This situation usually occurs during equipment emergency repairs; to minimize downtime, incomplete coking removal is the most common problem that arises. Generally, once it is known that the carbon removal is not thorough, re-baking in the furnace should be carried out; once the temperature in that area rises to 350 degrees, there is no need to increase it any further – maintaining that constant temperature is sufficient. If it rises too high, scorching accidents are very likely to occur; the temperature during scorching rises rapidly, which is very dangerous. Once it is detected that the temperature is out of control, quickly disconnect the two devices and introduce a large amount of steam to cool down. The regenerator also experiences a drop in temperature, pressure, and main air flow; if the situation cannot be controlled, the auxiliary combustion chamber is shut down and the main air supply is disconnected.

This post was last edited by Ocean Oasis on 2013-2-19 at 17:54. Generally, the coke located in the stripping section is difficult to remove; therefore, stripping steam can be introduced, which not only ensures proper functioning of the stripping section but also helps to cool the cyclone system and the outlet.

I usually keep the temperature of my device at 300 degrees, and I don’t raise it any higher； Prepare steam at the same time for use in extinguishing fires.