Slurry circulation

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1. Fluidization in both units is achieved by the main air flow, which keeps the catalyst fluidized within the regenerator. 2. Fluidization in both units takes place within the reaction-regeneration system; it is necessary to ensure circulation in the slurry system, otherwise the catalyst will be carried to the trays and cause blockages

Slurry circulation, simply put, is a process that must be maintained at the bottom of the distillation tower in order to wash the catalyst brought in from the reaction system.

Generally speaking, the fluidization of a catalyst refers to the normal circulation of a catalyst in everyday use； Single-reactor fluidization involves reversing the differential pressure between the two reactors, with the reaction pressure being higher than the regeneration pressure; the reaction system is separated from the regeneration system. The catalyst is located in the regenerator, with a small amount of main air being introduced along with combustion oil, so as to control the temperature properly.

Slurry circulation refers to the normal upward flow of the slurry; if this flow is interrupted, the catalyst carried by the reaction gases entering the distillation column is not washed by the slurry and can easily end up on the upper trays. Single-vessel fluidization means that the catalyst is fluidized only within the regenerator, provided that main air is supplied to the regenerator – otherwise fluidization is not possible

Single-reactor fluidization means introducing stripping steam and pre-lift steam, right? By introducing steam, won’t the amount of water in the distillation tower increase significantly?

The medium for single-container fluidization is the main air flow, which ensures that the catalyst remains in a loose state and does not become a dead bed

1. By “slurry circulation” mentioned here, does it refer to the operation of the slurry pump, with the slurry flowing into the fractionation tower through the upward counterflow column? At this time, the purpose of circulating the slurry is to ensure smooth upward flow within the tower as well as efficient discharge outside it. The reason why there is no restriction on downward flow is that after an emergency shutdown, there is no oil and gas nor heat source entering the distillation tower, so the temperature at the bottom of the tower does not rise excessively. However, it is still necessary to wash away the fine catalyst particles brought in by the reactant oil and gas (more precisely, steam) as they move upward through the tower. Smooth external discharge is essential for maintaining the liquid level at the bottom of the tower; when the solid content in the slurry is high, it is necessary to send the slurry outside to prevent catalyst from accumulating in the slurry system, especially in the heat exchangers. 2. Is single-regenerator fluidization the fluidization of the catalyst within the regenerator? I don’t understand how it becomes fluidized Please advise, thank you. Single-unit fluidization refers to the fluidization within the regenerator; it is necessary to ensure a proper supply of main air in this process. As for how to achieve fluidization, simply put, when hundreds or even thousands of tons of catalyst are placed in a container, main air must be supplied to prevent the catalyst from compacting. The main air is used to create turbulence. Additionally, if the temperature of the catalyst drops too rapidly, combustion oil can be introduced to maintain the temperature of the catalyst inside the regenerator, thereby facilitating an early resumption of feeding.