Dispersion Ebullating reactor

Reactors with moving solid phase Three-phase fluidized-bed (ebullated-bed) reactor Catalyst particles are fluidized by an upward liquid flow, whereas the gas phase rises in a dispersed bubble regime. A typical application of this reactor is the hydrogenation of residues. 

The H-Oil reactor (Fig. 21) is rather unique and is called an ebullated bed catalytic reactor. A recycle pump, located either internally or externally, circulates the reactor fluids down through a central downcomer and then upward through a distributor plate and into the ebullated catalyst bed. The reactor is usually well insulated and operated adiabatically. Frequently, the reactor-mixing pattern is defined as backmixed, but this is not strictly true. A better description of the flow pattern is dispersed plug flow with recycle. Thus, the reactor equations for the axial dispersion model are modified appropriately to account for recycle conditions. 

Lee et used the ebullated-bed reactor for catalyst preparation from AC and soluble metal precursors. In their study, the oil-soluble Mo and Co naphthenates were introduced with an AR into the continuous ebullated bed of AC granules (623 K and 6.9 MPa of H2). The co-dispersed catalyst exhibited high activity for HDS, HDM and HDAs at the optimal Co/(Co + Mo) ratio of 0.3. However, the HCR activity of the Mo/AC catalyst was greater than that of the CoMo/AC catalyst. 

Microcat-RC. Catalytic ebullated-bed hydroconversion process that operates at relatively moderate pressures and temperatures. The catalyst particles are uniformly dispersed throughout the feed, which results in a smaller distance between particles and less time for a reactant molecule or intermediate to find an active catalyst site. The hydrocarbon feed, micro-catalyst, and hydrogen are fed to the reactor. The effluent is sent to a flash separation zone to recover hydrogen, gases, and liquid products. The residuum from the flash step is then fed to a vacuum distillation tower to obtain a 565°C- product oil and a 565°C+ bottoms fraction that contains unconverted feed, micro-catalyst, and essentially all of the feed metals (Bearden, 1997 Mart et al., 2005). 

In the hydrodynamic model the reactor is divided into two zones the catalytic zone and the bubble column. Liquid flow in both zones is modeled with a dispersed flow model. The dispersion is between the bubble column and the ebullated bed. The gas flow and the liquid recycle flow are assumed to be plug flow. Gas-liquid mass transfer of Argon is also considered. 

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