Multifunctional entry method and device for downward flow tube reactor

Abstract

A device and a method for operating it for application in a vertical tube reactor with downward flow (downer), has the aim of ensuring the intimate mixing of the solid particulate catalyst with a reagent fluid. Homogeneous distribution of catalyst is due to the use of a plate having perforations. Said perforated plate normally allows the passage of a portion of the stream of catalyst. The other portion overflows the edge of the plate, flowing in the form of an annular curtain, near the inner surface of the surrounding tube of the device. After passing beyond the perforated plate, the curtain-flow undergoes a deflection produced by an annular screen, to be mixed with the stream originating from the orifices in the perforated plate. A hydrocarbon charge is injected below the perforated plate, forming a certain angle with respect to the direction of the downward flow of catalyst, by means of inlets distributed uniformly about cross sections of the surrounding tube. After the mixing region, the diameter of the device, when smaller than the diameter of the associated tube reactor, expands slightly.

We claim:  
     
         1 . Multifunctional entry method for a downward flow tube reactor for supplying and distributing catalyst and mixing it with a hydrocarbon charge, for application in a multifunctional entry device for a downward flow tube reactor, characterised in that catalyst is distributed by means of the use of a plate having perforations, part of the catalyst being distributed by overflowing the plate as an annular curtain, comprising the following stages: 
 a) effecting controlled entry of the catalyst inside the device;    b) injecting vapour into the region of the device immediately below a catalyst-entry valve;    c) collecting the catalyst in a collector/distributor vessel, the floor of which consists of a perforated plate, inside the device;    d) injecting vapour inside the collector/distributor vessel by means of a fluidization ring;    e) producing a distributed downward flow of catalyst through the orifices in the perforated plate;    f) producing a downward flow of catalyst which overflows the collector/distributor vessel in the form of an annular curtain, in the space between the collector/distributor vessel and the surrounding tube of the device;    g) deflecting the flow of catalyst in the form of an annular curtain towards the longitudinal axis of the device by means of an annular screen, in order to mix it homogeneously with the flow of catalyst originating from the holes in the perforated plate;    h) injecting a hydrocarbon charge and its intimate mixing with the catalyst;    i) flowing the resulting mixture to the reaction regions of the associated downer reactor.    
     
     
         2 . A method according to  claim 1 , characterised in that the flow in stage (i) is along a path where the diameter of the surrounding tube of the device can expand slightly.  
     
     
         3 . A method according to  claim 2 , characterised in that the walls of the surrounding tube form an angle with the vertical selected within the range of 0° to 4°.  
     
     
         4 . A method according to  claim 1 , characterised in that a hydrocarbon charge is injected by means of injector inlets inclined at an angle of from −30° to +30° with respect to the horizontal.  
     
     
         5 . Multifunctional entry device for a downward flow tube reactor for supplying and distributing catalyst and mixing it with a hydrocarbon charge, for application to the upper portion of said reactor, characterised in that it comprises: a predominantly cylindrical surrounding tube, a plate having uniformly distributed perforations formed in the bottom of a catalyst-collector/distributor vessel mounted axially inside the surrounding tube; control means for controlling the entry of catalyst into the device; means for injecting vapour into the device; a mixing region below the perforated plate; deflective means for deflecting a stream of catalyst overflowing the catalyst collector/distributor vessel, in the form of an annular curtain, towards the longitudinal axis of the device; and inlet means for injection of a hydrocarbon charge into the mixing region.  
     
     
         6 . Multifunctional entry device according to  claim 5 , characterised in that the device has a nominal diameter smaller than that of the associated downer reactor.  
     
     
         7 . Multifunctional entry device according to  claim 5 , characterised in that the lower portion of the surrounding tube has a diameter which expands slightly, after the mixing region and forms an angle of 0° to 4° with the vertical, up to the diameter of the section of the downward tube reactor where said device will be connected.  
     
     
         8 . Multifunctional entry device according to  claim 5 , characterised in that the control means for controlling entry of catalyst comprises a plug-type valve.  
     
     
         9 . Multifunctional entry device according to  claim 5 , characterised in that the control means for controlling entry of catalyst comprises a slide-type valve, with simple displacement, associated with means for redirecting the catalyst to the central portion of the entry region.  
     
     
         10 . Multifunctional entry device according to  claim 5 , characterised in that the control means for controlling entry of catalyst comprises a slide valve with double actuation.  
     
     
         11 . Multifunctional entry device according to  claim 5 , characterised in that said means for injecting vapour includes inlets mounted in the surrounding tube, in the region of the device between the control means for controlling the entry of catalyst and the collector/distributor vessel.  
     
     
         12 . Multifunctional entry device according to  claim 5 , characterised in that said means for injecting vapour includes an injecting ring, with one of multiple inlets and multiple holes, mounted in the surrounding tube in the region of the device between the control means for controlling entry of catalyst and the collector/distributor vessel.  
     
     
         13 . Multifunctional entry device according to  claim 5 , characterised in that said means for injecting vapour includes a fluidisation ring positioned inside the collector/distributor vessel.  
     
     
         14 . Multifunctional entry device according to  claim 5 , characterised in that said means for injecting vapour includes vapour-injecting inlets mounted in the surrounding tube, in the region of the device between the control means for controlling entry of catalyst and the collector/distributor vessel, and also a fluidisation ring positioned inside the collector/distributor vessel.  
     
     
         15 . Multifunctional entry device according to  claim 5 , characterised in that said means for injecting vapour includes a vapour-injecting ring, with multiple inlets or holes, mounted in the surrounding tube, in the region of the device between the control means for controlling entry of catalyst and the collector/distributor vessel, and also a fluidisation ring positioned inside the collector/distributor vessel.  
     
     
         16 . Multifunctional entry device according to  claim 5 , characterised in that said deflector means comprises an annular screen on the inner surface of the surrounding tube below the collector/distributor vessel, said annular screen having a cross section with a format suitable for deflecting an annular curtain of catalyst towards the longitudinal axis of the device.  
     
     
         17 . Multifunctional entry device according to  claim 5 , characterised in that said inlet means comprises hydrocarbon-charge injector inlets mounted in the surrounding tube, at the level of the mixing region, uniformly distributed around at least one transverse section of said tube.  
     
     
         18 . Multifunctional entry device according to  claim 17 , characterised in that there are said hydrocarbon-charge injector inlets at different levels in the outer tube and in that corresponding ones of said hydrocarbon-charge injector inlets, located at adjacent levels, have an angular offset between the respective mounting locations which corresponds to a rotation of the respective mounting planes about the longitudinal axis of the device of the invention.  
     
     
         19 . A multifunctional entry device according to  claim 17 , characterised in that the hydrocarbon-charge injector inlets are mounted with a positive angle of from 0° to 30° with respect to the horizontal so as to have a component of motion of the injected flow against the direction of flow of the catalyst.  
     
     
         20 . Multifunctional entry device according to  claim 17 , characterized in that the hydrocarbon-charge injector inlets are mounted with a negative angle of from 0° to −30° to the horizontal so as to have a component of movement of the injected flow along the direction of flow of the catalyst.