Catalyst loss
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Under what circumstances will the catalyst escape? Why does the catalyst escape when there are large pressure fluctuations in the regenerator?
The separation principle of a cyclone separator relies mainly on the difference in centrifugal forces generated during the rotational motion of the gas and solid phases, thereby achieving separation. The rectangular inlet pipe enters the device tangentially; the solid particles collide with the wall of the device and separate due to gravity. When the inlet wind speed is too low, the centrifugal force acting on the particles is insufficient, preventing effective separation. When the inlet wind speed is too high, the air flow resistance becomes excessive, resulting in high power consumption. Generally, an inlet wind speed of 10–15 m/s is appropriate. The regenerator experiences large pressure fluctuations; the catalyst separation efficiency is poor, leading to easy loss of the catalyst along with the flue gas
There are many reasons; an excessive amount of air can also cause it. The large volume of air reduces the settling speed of the catalyst, making it easier to carry the catalyst away along with it, resulting in secondary combustion in the dilute phase. Due to secondary combustion, a small portion of the catalyst is carried upward and lost along with the flue gas; the material level is too high. A high material level results in a shorter settling time for the catalyst, making it prone to loss; this is a design issue with the cyclone. An improperly designed or damaged cyclone can also easily lead to losses
The main causes of catalyst loss include abnormal operating parameters, equipment failures, poor quality of the catalyst, and excessively high local linear velocities during catalyst fluidization. Fluctuations in the regenerator pressure mainly cause fluctuations in the linear velocity at the inlet of the cyclone, which affects its efficiency and leads to catalyst loss along with the flue gas.
Generally speaking, on the one hand, equipment failures lead to the failure of the centrifuge and a decrease in its efficiency, while on the other hand, issues related to process operation are responsible for the reduction in centrifuge efficiency. Therefore, the regeneration pressure fluctuates greatly, the centrifugal separation speed changes significantly, which easily leads to catalyst loss.
Pressure fluctuations surely affect the efficiency of centrifugation; leakage is normal. Linear speed = Q/S, and S = P*s
Pressure fluctuations mainly affect the critical fluidization velocity and the critical entrainment velocity. Generally, the higher the pressure, the lower these two values are.
1. What everyone upstairs said is correct. . . 2. Fluctuations in the regenerator pressure directly affect the stability of the inlet velocity for centrifugal separation; if the speed of the centrifugal motion used for gas-solid separation is unstable, then the effectiveness of this method, which relies on gravity-driven sedimentation to separate solid catalysts, will be poor within the system involved in gas-solid separation. . . 3. The pressure stabilization measure for the regenerator is the main fan ； The second is a double-acting slide valve ； Third is the control of the settler pressure. . . . . . :loveliness:
The most common equipment failure is, first and foremost, a malfunction of the cyclone separator, resulting in poor separation performance； The second is a failure of the main air distribution pipe or distribution plate, resulting in abnormal fluidization.
Catalyst loss generally only occurs in systems that employ continuous catalyst regeneration, such as catalytic cracking, continuous reforming, S-SORB, etc. Different devices have different ways in which catalyst loss occurs. A brief introduction has been provided regarding the catalyst loss in catalytic cracking units; in continuous reforming units, catalyst loss is usually caused by the breakdown of the central tube or Johnson net in the regenerator (the structures of UOP and IFP regenerators differ).
Fluctuations in regenerator pressure affect the pressure drop in the centrifuge, which in turn affects the flow velocity of the flue gas and results in a poorer centrifugation effect.
Large fluctuations in regenerator pressure inevitably lead to changes in the pressure drop across the centrifuge, which in turn affects its linear velocity. Generally, the inlet linear velocity for coarse centrifuges should be kept below 22, while that for fine centrifuges should be kept below 24