Catalytic startup issue
Thread Content
Catalytic startup involves adding a catalyst at the time of ignition in the auxiliary combustion chamber, which can save a significant amount of time and energy; but what are the disadvantages of this approach?
It seems that the regenerator needs to be heated to 550 degrees as well, right?
The question on the 2nd floor is good~ :lol Hehe, it’s very important to line and dry the two devices before starting work!
It’s not the original start-up; of course, the original start-up requires lining.
It saves a lot of time??? If the temperature is raised to 550 degrees first and then a catalyst is added, burning oil can be sprayed at that point, allowing the furnace to be shut down
This seems to be the opposite of what the original poster said. Instead of saving time and energy, it actually prolongs the startup time. Since the furnace only heats the main air stream, strict temperature requirements exist, which hinders the heating of the catalyst; injecting oil is a more direct and effective method.
1. The unheated lining cannot withstand such wear. 2. The catalyst added absorbs a large amount of heat, making it difficult to raise the temperature. 3. The addition of catalyst increases the difficulty of operating the auxiliary combustion chamber. 4. The catalyst will flow out in large quantities through the self-sedimentator’s vent. 5. Most importantly, since the blind flange is in place at the inlet to the distillation tower at this time, the catalyst will accumulate in the large oil and gas line leading from the sedimentator to the distillation tower
The practice of adding a catalyst after ignition has been used multiple times at Qingjiang Chemical Plant, with good results; I read about it in a petroleum refining magazine.
During the startup and bedding-in period of the catalytic unit, the pressures in the two vessels are kept low. If catalyst is introduced into the system at this time, the high wind velocity in the regenerator will inevitably lead to significant loss of catalyst, which is not worth it.
It works well? Talk about the effects – has it shortened the project start-up period? Have the startup costs been reduced?
I think the temperature should be increased slowly; if it’s raised too quickly, the lining is likely to come off.
The premature addition of the catalyst means that the auxiliary heater has to heat not only the air but also the cold catalyst, a task that should normally be carried out by the oil burner, **increasing the load on the furnace. Moreover, it may cause catalyst loss in the regenerator and settler after being added. It is not only uneconomical but also hinders normal operations.
This is a solution that only someone from China would think of. The original poster must have been under pressure from their superiors to include a charging mechanism in the auxiliary combustion chamber. Conversely, even if there were no losses caused by issues such as uneven heating or material leakage, how much time could the original poster save at the earliest? How much benefit can it create? Catalytic cracking is already a highly mature technology; it’s better to avoid such opportunistic tactics.
Both devices have temperature rise curves: surface water is removed at 110 degrees, crystalline water at 320 degrees, and sintering at 500 degrees requires a constant temperature. Even if it’s not the first time the equipment is being used, the lining usually needs to be repaired, and the temperature must still be increased in accordance with the specified temperature rise curve.
Agree with Floor 9: loveliness:
The person on the 15th floor is right; it’s better not to resort to such petty tricks.
The owner’s statement is incorrect. When a catalytic cracking unit is brought online, the auxiliary combustion chamber is used to heat up the two reactors and dry their linings. Even if it isn’t the first time the unit is started, the linings still require repair to varying degrees during maintenance, and drying and dehumidification are also necessary； The temperature increase of the two devices should follow a specified curve, in order to prevent uneven thermal expansion of the device and avoid damage to it ； If the auxiliary combustion chamber is ignited, a catalyst is then added and the temperature is raised, causing the auxiliary combustion chamber to heat not only the main air flow but also the catalyst; as a result, the catalyst can be lost within the system, leading to increased costs.
The lining cannot be heated, and the catalyst is difficult to heat
The lining needs to be dried properly so there are no problems; otherwise it will come off
It’s really enlightening; I admire the courage. Generally, catalysts are added after the oil slurry circulation is established. How do you prevent and deal with fluid loss in the regenerator and the settler? I heard that your high-acid crude oils can be directly fed into catalytic processing; I’ll go there to learn from it whenever I get the chance*.
It is still necessary to add the reagent according to the prescribed procedures. However, once we started operation and added the reagent after removing air from the system, the temperature of the reactor decreased. Due to the tight schedule, we basically ignored the reactor temperature and added the reagent quickly before raising the temperature, and this did not result in any negative consequences