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Concept
Heterogeneous catalytic reactor
Résumé
Heterogenous catalytic reactors put emphasis on catalyst effectiveness factors and the heat and mass transfer implications. Heterogenous catalytic reactors are among the most commonly utilized chemical reactors in the chemical engineering industry.
Heterogenous catalytic reactors are commonly classified by the relative motion of the catalyst particles.
A fixed bed reactor is a cylindrical tube filled with catalyst pellets with reactants flowing through the bed and being converted into products. The catalyst may have multiple configuration including: one large bed, several horizontal beds, several parallel packed tubes, multiple beds in their own shells. The various configurations may be adapted depending on the need to maintain temperature control within the system. Serial connection of two reactors with option to dose oxidant between the stages enable under optimal conditions to increase the product yield in oxidation catalysis. By dosing intermediates or products between the stages, valuable information could be found concerning the reaction pathways.
The catalyst pellets may be spherical, cylindrical, or randomly shaped pellets. They range from 0.25 cm to 1.0 cm in diameter. The flow of a fixed bed reactor is typically downward. Packed bed reactor.
A trickle-bed reactor is a fixed bed where liquid flows without filling the spaces between particles. Like with the fixed bed reactors, the liquid typically flows downward. At the same time, gas is flowing upward. The primary use for trickle-bed reactors is hydrotreatment reactions (hydrodesulfurization and hydrodemetalation of heavy crude oil, hydrodeasphaltenization of coal tar). This reactor is often utilized in order to handle feeds with extremely high boiling points..
A moving bed reactor has a fluid phase that passes up through a packed bed. Solid is fed into the top of the reactor and moves down. It is removed at the bottom. Moving bed reactors require special control valves to maintain close control of the solids. For this reason, moving bed reactors are less frequently used than the above two reactors.
Source officielle
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