FR2623732A1 - Apparatus for injecting a hydrocarbon feedstock into a reactor - Google Patents

Abstract

An apparatus comprising (Figure 3) - an appreciably vertical reactor 1 - means 2 for introducing solid particles into the upper part of the reactor, - means 4 for draining solid particles in the lower part of the reactor, - at least one funnel or flared zone 25 the apex of which points downwards - means 7 and 8 for introducing the said fluid feedstock consisting of a liquid and a gas into the lower end of the reactor, under the said funnel 25. The apparatus is characterised by the presence of a device for injecting a feedstock, the device comprising: - at least one appreciably vertical leg or pipe 24 which perforates the said funnel - a spherical cap 26 which covers the upper end of the pipe 24, the lower base (or fringe) of this cap comprising a number of cutouts or a series of cutouts arranged on the major part of the perimeter of this base.

Description

The present invention relates to an apparatus for catalytic treatment (or hydrotreatment) of a fluid charge and more particularly of demetallization, desulfurization, hydrotreatment and conversion or hydroconversion of hydrocarbons, in a fixed or moving bed, as explained herein. -Dessous.

The invention is particularly applicable to catalytic treatments of liquid feeds, such as, for example, distillates derived from heavy petroleum crudes, residues from the distillation of atmospheric hydrocarbons and under vacuum, these treatments being carried out generally in the presence of hydrogen and or gaseous mixtures rich in hydrogen, on a bed of solid catalyst, the catalyst being used in particulate form (extruded catalyst, grains of various shapes, beads, etc.).

During such catalytic treatment, there is often a rapid catalyst deactivation, due to the presence of catalytic poisons, the formation of coke, the deposition of certain metals.

etc ...

This deactivation requires the frequent replacement of all or part of the catalytic bed.

In the apparatus of the invention, the withdrawal of the catalyst from the reactor is carried out progressively. The term "progressively" means that the catalyst can be withdrawn - either periodically, for example with a frequency of 1/10 to 10 days or more, by withdrawing only a fraction, for example 0.5 to 15% the total amount of the catalyst. Depending on the needs, more catalyst can be withdrawn and, for example, up to 100% of the total amount of catalyst, that is to say all of the catalyst, can be withdrawn.

The withdrawal frequency of the catalyst can be much faster, (of the order of a minute or a second for example), the amount withdrawn being reduced in proportion - or continuously.

The fresh catalyst is introduced into the upper part of the reactor, the system for injecting the feedstock and the hydrogen together in the form of a mixed fluid which travels from bottom to top of the reactor, is the object of the present invention. .

The devices according to the invention are thus suitable for injecting a filler to be placed in contact with catalytic particles of cracking, hydrocracking, hydroreforming, aromatic hydrocarbon production and isomerization reactors. paraffinic, naphthenic or aromatic hydrocarbons, various reactions of hydrogenation, hydrotreatment, dehydrogenation, alkylation, transalkylation, hydrodecyclisation, hydrodealkylation, treatments, hydroviscoreduction, etc.

reactors where the charge and / or the gases injected there, travel from the bottom up.

The fluid charge, which is generally a mixture of a liquid and a gas, is introduced into the reactor or the enclosure containing catalytic particles, by distribution members located at the bottom of the reactor or the enclosure and flows countercurrent to the catalyst, from bottom to top ("up-flow"), before being removed, after its treatment, to the upper part of the reactor (or the enclosure that is arbitrarily designated "reactor" in following the present description). The flow of the catalyst, by gravity, ensures a regular descent of the catalytic bed, while the upward flow of the fluid load allows in particular an easy adjustment of the residence time and ensures a controlled detassment of the bed.

Moreover, the counter-current circulation of the feedstock and the catalyst makes it possible to obtain a catalytic conversion, since the fresh catalyst introduced at the top of the reactor processes an almost converted feedstock (that is to say essentially containing compounds whose transformation is difficult), while at the bottom of the reactor, the used catalyst processes a fresh charge (ie rich in easy-to-process compounds), which effectively accomplishes the first stages of the conversion. This results in a systematic use of the catalyst in the reactor, a thermal profile of the catalytic bed more regular than in a co-current type circulation, with, in particular, at the bottom of the reactor, a more moderate temperature reducing the risks of coking the catalyst.

US Pat. No. 3,826,737 discloses a catalytic conversion process in a moving bed. This method is, however, more particularly adapted to the co-current circulation of the catalyst and of the liquid charge, the latter being discharged at the base of the reactor through a cylindrical grid disposed at the base of a catalyst discharge cone and which supports the catalytic bed.

Such a method has the disadvantage of a risk of fouling of the gate by catalyst grains pushed against this gate by the liquid charge discharged from the bottom of the reactor. This can result in an irregular distribution of the fluids in the catalyst, difficulties in the flow of the catalytic bed, with the risk of blockage of certain zones of this bed, as well as an increase in the erosion of the catalyst due to the friction between blocked grains and free grains of the catalyst bed and between free catalyst grains and the discharge grid of the liquid charge.

To overcome the disadvantages mentioned above, the patent
US-A 4571326 of the applicant had proposed two devices illustrated in both Figures 1 and 2, not in accordance with the invention. The technique consisted in injecting the liquid and the gases under the wall which supports the catalytic bed while ensuring the gas-liquid distribution by a suitable device.

More particularly, this result was obtained by a process (with gradual withdrawal of the powdery solid particles from a generally closed space) to introduce into said space a fluid charge consisting of a liquid and a gas (generally hydrogen). gene), said generally closed space having substantially the shape of an elongated and substantially vertical volume of revolution, the solid particles being introduced to the upper part of the chamber and progressively withdrawn into the lower part of the chamber after having walked from top to bottom in the said enclosure, while the fluid charge is introduced at least in part and generally continuously in the lower part of said enclosure and is withdrawn in the upper part after having walked from bottom to top in the said enclosure, in which the solid particles are progressively withdrawn by the lower end of at least one z one flared having a shape depending on the geometry of the reactor and in general the shape of an inverted cone or an inverted pyramid, ie a cone or a pyramid whose top is turned downwards , aperture in which is pierced an opening of suitable size for the evacuation of solid particles, the wall of said flared zone being substantially and regularly discontinuous, that is to say dotted with at least several regularly spaced openings each having a sufficiently large size small to prevent the solid particles from passing through said wall but large enough to allow the passage through these openings of an upward flow of the fluid charge, the method being characterized in that the fluid charge was injected into the part lower of said enclosure by at least one distribution zone of particular shape and located below said wall.

The technique of the first device, illustrated in FIG. 1, consisted in disposing, in the reactor (1), (the reference numerals in FIGS. 1 and 2, which are not in conformity with the invention, are for more understanding those given in Figures 6 and 7 of the patent
US 4571326) between the grid (5), which supports the catalytic bed (withdrawal of the catalyst via the pipe (4) and the ramps such as (7), load distribution zones schematized by the disks (8), a additional grid (14) whose perforations (20) are small enough not to let through most of the liquid phase of the fluid (introduced through the distribution zones (8), thus allowing most of the phase to pass through Gaseous fluid. Continuous walls or barriers (15) (ie not perforated or not perforated) and substantially vertical, in the form of chimneys for example, are arranged in a generally regular manner under this grid (14). ) resting on this grid (and whose lower ends are located sufficiently low in the reactor, generally at a level higher than that of the distribution zones (8)) and thus delimit a compartment (18) and chimneys (13) : the gaseous fraction of the fluid reaches for the most part (arrows (17), the grid (5) through the compartment (18) and the orifices (20), after passing through zones (22) of accumulation and separation of a liquid phase and a gaseous phase. Trays or baffles (21) are arranged under the lower ends of the chimneys (19) (and above the level of the distribution boxes) so that the mixed fluid injected by the distribution zones (8) and whose path is represented by the arrows (13), accumulates in the compartments (18) creating liquid and gaseous clusters (22), most of the liquid rushing to through the chimneys (19) (path shown by the arrows (16)).

The device described above thus serves as a mixer and dispersion of the fluid charge.

The devices of FIG. 1 could be further improved in this US Pat. No. 4,571,326. It had indeed been observed that the gases, whose path is represented by the arrows (17), tend to be directed and accumulate in the beta angles delimited by the walls of the funnel or funnels (5) and the reactor wall (1). To avoid the migration of the gas under the upper part of the funnel and thus improve the distribution of gas and liquid throughout the bed section, the gas phase (from the orifices of the upper part of said spaces) is made to flow. through a plurality of parallel non-communicating elongated zones and substantially vertical or oblique or partly vertical and oblique parts, which thus force the gaseous particles to take a controlled path under the funnel or under the funnels. FIG. 2 illustrates this improvement. it contains all the accessories of Figure 1 and furthermore, there is shown a plurality of vertical elongated areas separated by vertical barriers (23). On the right side of Figure 1, the lower ends of these barriers are all at the same level; these ends are at different levels on the left side of Figure 1. The length of the barriers and their level depends mainly on the geometry of the distribution areas.

In order to further improve the dispersion of the fluid in the catalytic bed and to always obtain a regular dispersion in this catalytic bed with large flow rate ranges, the present invention proposes a new device for the joint introduction of the charge and the gas. used (hydrogen), which opens not under the grid that supports the catalyst but in the catalyst bed itself. The first consequence in the use of this device is that it can be used to support the catalyst either a grid (which can often clog) but a wall whose surface is substantially continuous, that is to say without openings such as slots or perforations sufficiently small to not pass the grains or catalyst particles but large enough to pass a charge or gases.The only openings in this wall are those arranged to pass (in addition to the exhaust pipe of the catalyst ) the legs or tubing of the device for injecting or distributing the charge and gases.

In the present invention, (see FIG. 3), the reactor (1) comprises, at its upper part, fresh catalyst introduction means (new or regenerated) schematized by the conduit (2) which discharges the catalyst particles to feed a catalyst bed (3) fixed or mobile.

The catalyst flows by gravity into the reactor and is evacuated progressively through the pipe (4) to the lower part of the reactor (1), via at least one extraction funnel (25). This or these funnels, are in the form of a flared zone having the shape of a cone or an inverted truncated cone or a pyramid or truncated pyramid overturns, that is to say a cone ( or truncated cone) or pyramid (or truncated pyramid) whose apex is turned downward as indicated above the wall or the walls of this or these funnels are substantially continuous and do not include the passage of the pipe (4 ) of the catalyst withdrawal, that openings for the arrangement of the legs, legs or pipes (24) of the load injection device described later.

The alpha angle that the axis of the cone (or the axis of the pyramid if the funnel has this shape) with one of the generators of the cone (or one of the edges of the pyramid) is generally understood between 10 and 800, preferably between 20 and 500 or between 30 and 400C.

The fluid charge is therefore introduced to the lower part of the reactor 1 by at least one distribution zone comprising for example a distribution ramp (7) (horizontal, oblique or vertical or disposed in any suitable manner, for example vertical in certain industrial reactors ) provided with at least one end piece (8) of appropriate shape, for example in a star shape, in the form of a jet breeze, etc., in order to disperse the fluid in multiple directions (shown schematically by the arrows (13)). )).

The fluid or mixed fluid charge, because formed of two phases (liquid and gas) back in the reactor against the current of the catalyst before being discharged to the upper part of the reactor via collection means and evacuation schematized by the pipe (11), having the shape, for example, a rake consisting of collector tubes connected to a discharge conduit.

The mixed fluid injected by a dispensing zone (7) is directed towards the funnel or funnels that support the catalytic bed by first forming before reaching this or these funnels a zone (22) of liquid accumulation. gaseous mixed fluid (liquid and gaseous clusters); unlike the prior art described in US 4571326, there is no need to proceed at this level to a liquid-gas separation. Legs (24) are sinking into the upper level of the zone (22). Under the force of the operating conditions which prevail in the reactor and under the effect of the mixed fluid inlet conditions, in the reactor bottom said mixed fluid rushes and rises through the legs (24) and penetrates into the engine. space allocated to the catalytic bed above or flared funnels that support this catalytic bed.A cap (26) disposed above each leg acts as jet jet fluid thus injected and allows it to be sent in several directions in the catalytic mass. Each cap, in addition, aims to protect and isolate the upper end of each leg by preventing direct contact between the tip and the catalytic particles. The cap may have any suitable shape to cover properly as an umbrella, the upper end of each leg (24) and at least part of the upper part of each leg (24). The cap may be for example a half-sphere (Figure 7E), a truncated cone (Figure 7A), a truncated pyramid (Figure 7C), a prism (Figure 7H), a parallelepiped (Figure 7G).

A particular position of the cap is the position in which one of the walls of the cap is substantially contiguous to the inner wall of the reactor, as is the case in Figure 3 for a cap (26). The wall of the cap contiguous to the inner wall of the reactor is either substantially flat or curvilinear to suit suitably the internal wall of the reactor. To simplify the drafting of this patent application, it will be accepted in the present invention that such a wall of the cap contiguous (tangent) to the inner wall of the reactor is substantially flat; this tolerance is fairly close to reality because of the relatively large diameter of the reactor in comparison with the dimensions of each cap.As examples of caps whose wall is substantially contiguous to the inner wall of the reactor, there will be mentioned quarter sphere (Figure 7F), the half-truncated cones (FIG. 7B), the half-truncated pyramids (FIG. 7D) and the prisms (FIG. 7H). A particularly appropriate type of arrangement is illustrated in each of these figures, in FIGS. 4 and 5. The cap 26 is formed by the combination of a prism (28) and a half-truncated pyramid (29) which rely on the inner wall of the reactor; As indicated above, according to the possibilities of the manufacturers of these types of equipment, the walls of this prism and this half pyramid trunk that rely on the reactor wall, can be flat or curvilinear to better marry the shape of the reactor wall.

Moreover, for the mixed fluid to be well dispersed in the catalytic mass, after striking the upper base of the cap, it is necessary that the base of this cap, that is to say, the bangs is not continuous but either mostly cut across its entire perimeter. This fringe may have various conformations, for example be in the form of saw teeth (27) in Figures 3 and 7A to 71 or in the form of crenellations (30) as in Figures 4 and 5, in the form of festoon or notched or in the form of sinusoid as in Figure 7J. The height of each cut on the barn (for example the height of each tooth, each slot or each notch represents 0.1 to 30 of the total height of the cap, preferably 2 to 25 h and more particularly 5 to 15 %).

An arrangement according to the invention, in particular for small reactors, consists in arranging the caps all along the internal periphery of the reactor. Depending on the size of the caps, one could design for example a series of 2 to 30 caps, preferably 6 to 15 or 6 to 12 tangents contiguous or not between them. FIG. 6 represents a section of the reactor (1) comprising a combination of a leg (24), these caps being distributed concentrically around the axis (4) of withdrawal of the catalyst at the bottom of the truncated cone or pyramid supporting this catalyst. For large reactors, it is possible to use in association the different types of caps described above and distributed in the reactor. For example in a large reactor, provided with several funnels (contiguous), it can have 2 to 800 caps and legs distributed on the periphery of these cones.

(1 to 100 draw cones).

Thus the apparatus according to the invention (see Figure 3) comprises a reactor (1) substantially vertical and of substantially elongate and cylindrical shape.

means (2) for introducing solid particles into the upper part of the reactor; means for withdrawing the solid particles in the lower part of the reactor, consisting essentially of at least one substantially vertical pipe (4); at least one funnel or flared zone (25) whose apex is turned down and which supports said solid particles and which is arranged in the lower part of the reactor and perforated so as to allow the passage of the tubing 4 and from at least two tubing (24) forming part of at least one device for injecting a fluid charge, said device being defined below.

- Means (7) and (8) for introducing said fluid charge consisting of a liquid and a gas into the lower end of the reactor, under said funnel (25).

- Tapping means (11) of the reaction effluents in the upper part of the reactor (1), the apparatus being characterized by the presence of a device for injecting a charge, the number of this device in the device being at least equal to two, each device comprising - a substantially vertical jamb or tubing (24) which perforates the said funnel, ie whose lower end is situated under the walls or walls of said funnel (and above means (7) and (8) for introducing said charge) and whose upper end is located above said funnel and relatively close to said funnel, - a cap (26) which covers the end upper section (24), the lower base (or fringe) of this cap, having a plurality of cuts or a series of cuts arranged over most of the perimeter of this base.

Preferably, for a single cone reactor, the legs (24) are arranged in the vicinity of the periphery of the funnel, near the inner wall of the reactor.

Claims (7)

1 / Apparatus comprising (see Figure 3) - a reactor (1) substantially vertical and of substantially elongate and cylindrical shape. - Means (2) for introducing solid particles into the upper part of the reactor, - means for withdrawing solid particles in the lower part of the reactor, consisting essentially of at least one pipe (4) substantially vertical. - at least one funnel or flared zone (25) whose apex is turned down and which supports said solid particles and which is arranged in the lower part of the reactor and perforated so as to allow the passage of the tubing (4) and at least two tubings (24) forming part of at least one device for injecting a fluid charge, said device being defined below. - Means (7) and (8) for introducing said fluid charge consisting of a liquid and a gas into the lower end of the reactor, under said funnel (25) - withdrawal means (11). ) of the reaction effluents in the upper part of the reactor (1), the apparatus being characterized by the presence of at least one device for injecting a charge, the number of these devices in the apparatus being at least equal to two, each device comprising - at least one leg or pipe (24) substantially vertical which perforates said funnel, that is to say whose lower end is located under the walls or walls of said funnel (and above the means ( 7) and (8) of introduction of said charge) and whose upper end is located above said funnel and relatively close to said funnel, - a cap (26) which covers the upper end of the tubing (24), the lower base (or fringe) of this cap, so many cuts or a series of cuts arranged on most of the perimeter of this base. 2 / Apparatus according to claim 1 wherein said cap in the form of a volume selected from the group consisting of the truncated cones (fig.5A)> the half-truncated cone (fiv.53), the pyramid trunks (fig.SC), the half-truncated pyramids (fig.5D), the half-spheres (fig.5E), the quarter-spheres (fig.SF), the parallelepipeds (fig.SG), the prisms (fig.5H ), the combinations of half truncated pyramids and prisms (fiv.51) and the figures equivalent to the previous figures. 3 / Apparatus according to claim 1 wherein the height of the blank is about 0.1 to 50% of the total height of the cap. 4 / Apparatus according to claim 3 wherein the height of the cut represents 2 to 25% of the total height of the cap. 5 / Apparatus according to claim 1 comprising 2 to 800 caps 1 to 100 cone withdrawal cones 6 / Apparatus according to claim 1 comprising 6 to 15 caps 7 / Apparatus according to claim 6 wherein at least 4 caps are disposed adjacent to the inner wall of the reactor, concentrically around the tube (4) for withdrawing the catalyst. 8 / Apparatus according to one of revendicatons 1 to 7 wherein the cap is a juxtaposition of a quarter of a pyramid and a prism. 9 / Apparatus according to one of claims 1 to 8 wherein the legs (24) are arranged at the periphery of said funnel and near the inner wall of the reactor 10 / Apparatus according to one of claims 1 to 9, having several funnels or flared zones and having 2 to 800 caps and jambs distributed on the periphery of these cones.