Comparison between moving bed and fluidized bed?
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I don’t understand why the mobile bed is called a mobile bed! What movement does this movement refer to? What is the difference between its movement and fluidized bed?
The moving bed uses 3-6mm pellet catalyst. In the reactor, the oil and gas move upwards and leave the reactor, while the catalyst moves downwards and leaves the reactor. The flow directions of reactants and catalysts are opposite. The fluidized bed uses a catalyst of tens of microns, and the oil, gas and catalyst move upward and leave under the riser.
As the predecessor of the fluidized bed, the moving bed is a transitional type between the fixed bed and the fluidized bed. The catalyst moves slowly, the heat is easy to accumulate, and it is difficult to disperse evenly. Later, with the invention of efficient molecular sieve catalysts, the reaction time* * Shortened, this can increase the line speed, so the fluidized bed appeared.
The bed in which solid particles are in a tightly packed state and the particles are stationary is called a solid bed. The bed layer increases with fluid velocity. Fluid and solid particles enter the reactor at the same time. They contact each other and react while the particles move. This reaction bed is called a moving bed. A bed in which the particles in the bed are out of contact and the particles are suspended in the fluid and move in all directions is called a fluidized bed. The bed height and void ratio increase with the flow rate, but the bed pressure drop basically does not change with the flow rate.