FR2474337A1 - FLUID DISPENSER FOR CATALYTIC REACTION ZONES WITH FIXED BED - Google Patents

Abstract

THIS DISPENSER IS INTENDED TO BE MOUNTED IN A CATALYTIC REACTION CHAMBER, TO DISTRIBUTE A FLUID, IN PARTICULAR COOLING, IN THE VOLUME OF A FIXED BED OF CATALYST PARTICLES, INCLUDES AN INPUT DUCT 4 HAS FOLLOWED A DIAMIZER OF HOUR REACTION AND WHICH COMMUNICATES BY SMALL VERTICAL TUBES 8, 9, WITH THE INTERNAL PERFORATED DISTRIBUTION DUCTING TUBES 6 FOLLOWING STRINGS OF THE HORIZONTAL SECTION OF THE REACTION CHAMBER PERPENDICULAR TO THE INLET DUCT. EACH TUBE 6 IS ENCLOSED IN AN EXTERIOR TUBE 5 OF LARGER DIAMETER AND ALSO PERFORATED, OF WHICH IT IS JOINED BY PAIRS OF SPACER WASHERS. EACH PAIR OF SPACER WASHERS DELIMITS ONE BEDROOM. IN THIS CHAMBER, THE INTERIOR TUBE PRESENTS TWO SMALL HOLES OF 1.6MM OPPOSED ON THE SAME HORIZONTAL DIAMETER AND WHICH PROJECTS THE FLUID AGAINST AN UNPERFORATED PART OF THE WALL OF THE OUTER TUBE 5. IN THE SAME CHAMBER THIS TUBE 5 IS BORED BY FOUR HOLES OF 19MM DIAMETRALLY OPPOSED TWO BY TWO AND OFFSET 30 FROM THE VERTICAL DIAMETER OF THE TUBE.

Description

The present invention relates to the distribution

  of a fluid in the reaction zone of a catalytic reactor

than.

  The fluid dispenser according to the invention is

  designed for use in widely used treatments

  in the petroleum and petrochemical industries and in

  especially in treatments that involve the use of fixed bed catalytic reaction zones. The fluid dispensing device according to the invention is applicable to

  the distribution of a heating fluid in a mass of cata-

  lyser in the case of a mainly endothermic process

  that or the distribution of a cooling current in

  a catalyst mass in the case of an exothermic process

  than. The distributor, applicable to treatments carried out in

  vapor phase, in the liquid phase and in the mixed phase, serves

  producing a liquid stream, a vapor stream or a mixed vapor / liquid stream in the reaction zone. For

  purpose of clarity and brevity, but without the intention of

  the invention, the description and the following description of the

  the introduction of a cooling current to the

  state of steam in an exothermic process that is driven

in mixed phase.

  Mixed phase hydrocarbon conversion reactions generally occur as exothermic processes in which the fresh feed predominates in hydrocarbons boiling above the gasoline or boiling range of the gasoline. naphtha

  that is, above a temperature of 204 OC at the pressure of

  atmospheric pressure, Frequently, the reagent stream

  mixed phase is composed of hydrocarbon components

  quids and a hydrogen-rich vapor phase. The subjects

  raw materials include Kerosene fractions,

  heavy and heavy (obtained by distillation at atmospheric pressure

  pheric or vacuum) and heavy asphaltenic oils containing constituents which boil at a temperature above about 566 ° C. Naturally, the possibilities

  application of the invention are not based on any

  particular hydrocarbon first, or on one or more

  particular reactions used. These reactions

  take hydrocracking, hydrogenation, desulfurization

  and / or denitrogenation, hydrotreatment and various combinations of

  of these treatments, all of whom are users of hydro-

  gene and, consequently, of a predominantly exothermi-

  than. Although the dispenser described above is capable of uniformly distributing the reagent stream when this

  last is initially introduced into the reaction vessel.

  it is mainly intended for the introduction of

  inside a catalyst of a quenching fluid or cooling current, which will be designated

  in the following by "coolant".

  An essential factor for the success of a mixed phase hydrogen-consuming process is the uniformity of the reagent stream distribution throughout the bulk of the catalyst particle bed. This is particularly true for the interior areas of the catalyst bed in which the cooling stream is introduced. Continuous contact of the hydrocarbon phase with hydrogen

  throughout the bed mass of catalyst particles equi-

  is worth to reactions consuming hydrogen. At the points of introduction of cooling current, that this current

  whether in the liquid state or in the vapor state, it is also

  important to evenly distribute the cooling current

  in the reagent stream to ensure uniformity

  equally important, the cooling of the reagent stream or the heat transfer to the

  cooling. The dispensing device according to the invention

  vention makes it easy to obtain the necessary results.

  A main object of the invention is to provide a device for distributing a fluid uniformly in a bed of catalyst particles. -A corollary goal consists

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  & evenly distribute an external fluid stream into

  a stream of reagents which passes through a fixed bed of particles

the catalyst.

  More specifically, in an exothermic reaction, an object of the invention is to make it possible to obtain a uniform heat transfer from the reactant stream to the coolant stream introduced at an intermediate point.

  catalyst particle bed. Another goal is to obtain

  create an intimate mix between a stream of external fluid

and the internal stream of reagents.

  These and other objects of the invention are readily

  in a fixed-bed catalytic reaction chamber by the use of a fluid dispensing device which, in one embodiment, includes

  the following elements, arranged in such a way as to cooperate: (a) a

  fluid inlet, (b) a first set of

  spaced and perforated fluid distribution, which are in common

  free communication with said fluid inlet conduit and

  placed in a plane perpendicular to the vertical plane which

  holds the axis of said fluid inlet duct and, (c) one of

  xth set of perforated fluid distribution ducts

  having a nominal diameter greater than that of the first

  distribution ducts, each of which is arranged coaxially and concentrically around each of said first ducts

  of distribution. This embodiment may furthermore be

  characterized in that the fluid dispensing device occupies between 60.0% and about 90.0% of the section

  horizontal of the reaction chamber.

  Other features and advantages of the invention

  will appear in the detailed description which will follow

fever.

  In one embodiment, disks or washers

  the spaced rings whose large diameter is roughly

  equal to the inside diameter of the second (or larger) con-

  distribution channels surround the first

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  tribution (or small ducts) and are arranged roughly

  perpendicular to the longitudinal axis of these ducts.

  It should be recognized that the prior art includes a wide variety of fluid delivery devices for introducing (1) a stream of reagents

  in a mixed phase or single phase in a reaction zone

  catalytic converter, (2) a cooling or heating current in the vapor state and / or in the liquid state in one or

  several intermediate points in a fixed bed of particles

  the catalyst, and (3) the mixed phase effluent from

  a higher catalyst bed in the catalyst bed.

  immediately below. Most of the prior art fluid dispensing devices use a horizontal plate through which a large

  number of descending columns. This technique is illustrated

  by United States patents. 3,146,189; 3,378,349 and

3,524,731.

  In the prior art, dispensing devices similar to those of the present invention are found, as seen in the EUoA patent. No. 2,632,692. In this case, the dispensing device is located in a region containing no catalyst, between two plates.

  horizontal perforations. In this example, the device

  takes two concentric toroidal rings perforated

  interconnected by a transverse duct which, in turn, communicates with the inlet duct which conveys the fluid

  It should be noted that each toroidal crown

  dale is unitary, ie the device does not have a second toroidal ring entirely contained in

the limits of the first.

  The dispensing device disclosed in U.S. No. 2,860,955 is more closely resembled to the fluid dispensing device according to the invention (plan view of Fig. 2 of this patent). Here, the inlet duct tangentially introduces the mixed phase fluid stream into

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  a separation zone. The liquid constituents flow up and down in a horizontal manifold which, in turn,

  feeds a series of perforated distribution ducts

  perpendicularly. Here too, each of the distribution ducts is of unitary construction. The U.S. Patent No. 3,208,833 discloses a fluid dispensing device which resembles that of the aforementioned Patent No. 2,632,692. However, here the device,

  which includes a number of coacenter perforated crowns

  Rectangular section, is capable of being swept in reflux for the removal of the retained fluid. These segments

  The rings are connected to each other by a number of

  hollow tubular elements of short length which distribute the

  feed fluid in all crowns

  tribution spaced. It will also be noted that all

  Distribution crowns are of unitary construction.

  As indicated above, the fluid distribution device according to the invention can be adapted for use in fixed-bed catalytic reactors in which the reactions are carried out in the vapor phase, in the liquid phase or in the phase. mixed. In addition, the device can be used to initially dispense the reagent stream into the reaction chamber or to dispense a heating agent stream or a cooling stream.

  at one or more intermediate points in the bed of

  catalyst particles. The following statement will concern

  a mixed-phase exothermic reaction chamber in the

  what the exothermic nature of the reaction is controlled

  or moderate by the use of hydrogen cooling.

  do not in the vapor state. The distribution of a current of

  cooling in a fixed bed of catalyst particles according to the invention is based on the recognition that, until now, the means had not been found.

  to alleviate the difficulties and problems of obtaining

  (1) a uniform and intimate mixture of

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  cooling and circulating reagent stream; and (2) uniformly transferring heat to the cooling stream throughout the cross-sectional area of the catalyst particle area at the various coolant introduction points.

  In the remainder of the description of the invention, it is

  range of dimensions and particular values

  these dimensions. It goes without saying that these intervals and

  their particular dimensions are given only as

  illustrative and not limiting. The precise form of a

  Positive distribution of fluid depends on many

  which are related to the particular treatment in which the device is to be used. These considerations

  include at least the following: the physiological characteristics

  the chemical and the raw material constituting the charge or the current of reagents; the character of the reactions to be performed and the desired quality of the product;

  the feed rate of the feedstock; the dimensions

  catalytic reaction chamber; the quantity of

  catalyst disposed in this chamber; and the degree exother-

of the reaction undergone.

  According to the invention, the cooling stream is introduced into the reaction chamber via an inlet duct

  which communicates with a series of distribution ducts

  drilled, each of which is housed in a perforated outer conduit a-

  having a larger nominal inside diameter. Each conduit

  of cooling distribution consists of two tu-

  besides perforated coaxial and concentric. The cooling inlet duct is in direct communication only with the small diameter or inner duct distribution duct

  and it is aligned with the diameter of the reaction chamber.

  Two-pipe distribution ducts are spaced apart and

  placed in a plane that is perpendicular to the vertical plane

  containing the central axis of the fluid inlet duct

  froidissement. Cooling distribution ducts

247433.7.

  may be constituted by toroidal crowns

  those described in the prior art or by

  individual ducts closed at both ends. In this-

  the last configuration, its central axes distribution ducts are arranged along parallel ropes of

the reaction chamber.

  In the fluid distribution devices of

  more conventional cooling, difficulties have been encountered resulting from the deformation of the device to heat or

  the irregularity of the charge and the distribution of

  sor. This results in the fact that the pipes

  in different parts of the catalyst bed that function-

  at different pressures, which leads to a distribution of

  irregular temperature of the heat. Moreover, the deformation

  of the device allows the fluid to flow from

  the pressure towards the low pressure areas, which also contributes to poor heat distribution and unevenness of the mixture throughout the mass of the catalyst particle bed. Distribution ducts

  two tubes of the device according to the invention provide easy

  solutions to these problems. Thanks to the presence of

  large external duct, the deformation is practically inexistent.

  istante, even in very severe working conditions.

  Deformation of the device and irregularity of

  resulting from this deformation are also eliminated

  by the presence of discs or stabilizing washers

  spaced apart and surrounding the inner tube, and whose large diameter is about equal to the inside diameter of the larger outer duct, and which are arranged at little

  close perpendicular to the longitudinal axis of this duct.

  Perforations in the inner and outer ducts

  are contained in individual interior chambers

  formed between the discs of the various pairs of discs

  stabilizers. The cooling fluid delivered by a given perforation of the inner tube can therefore be introduced into the catalyst only through the perforations

  of the outer conduit which are located between the static discs

  bilisers of the same pair. In addition, there are annular stagnant areas between the perforations which tend to oppose the transfer of heat to the cooling fluid. In other words, the coolant

  does not heat up when running through the distribution duct

  inside towards the extremities of this

  deny. The fluid distribution devices are designed to represent a pressure drop of about 0.3 to about

  1.0 atm through the perforations of the small duct or

  inner diameter, which have a diameter of about 0.8 to about

  4.0 mm. The perforations of the inner duct are

  900 to the vertical axis and generally two of these perforations are provided only in each individual inner chamber bounded by two stabilizing disks. The perforations of the larger outer distribution duct have a nominal diameter of about 16 mm to about 22 mm and are preferably chamfered

  inward (towards the center of the duct). These perforations

  The vertical axis is 30 and each individual inner chamber contains from two to about four perforations of the outer conduit. The small holes are therefore arranged so as to project from the inner duct

  on an unperforated inner surface of the outer conduit.

  The entire fluid distribution device occupies

  between about 60.0% and about 90.0 So of the horizontal section.

  bed of catalyst particles. The report of the di-

  meter of the outer duct to that of the inner duct is

  in the range of about 2.0: 1.0 to about

4.0: 1.0.

  When high velocity cooling vapors are injected into the catalyst bed, care must be taken to avoid excessive wear of the catalyst particles. In the case of the fluid dispensing device according to the invention, the velocity of the vapors coming out of the holes of the inner duct is broken.

  by projection against an imperforate area of the outer duct

  laughing. If the outer tube is surrounded by a perforated screen, the speed is again broken as the vapors are discharged into the catalyst bed. An intimate and uniform mixture is obtained between the cooling fluid and the internal reagent stream by arranging the perforations

  of the outer duct at 300 from the upper extremities

  upper and lower vertical axis. This promotes the

  flow of the reagent stream at the precise points of introduction

  duction of the cooling fluid. The arrangement according to the

  The invention takes advantage of the jet effect of coolant vapors exiting through the small perforations to efficiently circulate the reagent stream through the individual interior chambers between the pairs of stabilizing disks. In addition, the entire cooling device closes a large part of the section of the catalyst bed, so that there is a relatively low pressure drop across the bed of

  catalyst in the spaces between different

  cooling drums. This pressure drop also has the effect of encouraging the stream of reactants to flow preferably through the annular spaces to the right of the points of

  cooling rather than through the catalyst.

  To continue to describe the distribution system

  According to the invention, reference is made to the accompanying drawings which show the various embodiments of this device. Since the drawings are presented for the sole purpose of making it possible to clearly understand the layout of the dispenser, its construction and method of

  they have not been drawn on a scale

  cise. As indicated above, the dimensions of each particular device depend on a great diversity

  processing considerations as well as

  of the catalytic reaction chamber.

  In a given device, intended for use in

  a catalytic reaction chamber having an integral diameter

  Effective volume of approximately 3.7 m, 25 double-tube distribution ducts are used. These ducts are arranged on centers of about 12.7 cm, with about 3.8 cm between

  adjacent ducts. The inner duct has a diameter of

  2.54 cm and holes drilled in this duct have a di-

  meter of about 1.6 mm; the outer pipe has a diameter of 7.6 cm and the holes drilled in this pipe have a diameter

  1.9 cm. In each of the individual interior rooms-

  each delimited by a pair of stabilizing disks

  spaced 2.54 cm apart, two 1.6 mm holes are provided and

  be 1.9 cm holes. The holes are spaced 7.6 cm

  be centered along the axis of the duct.

  In the accompanying drawings, FIG. 1 is a plan view of the fluid dispensing device 1 housed in a catalytic reaction chamber 2. The cooling fluid stream is introduced through an inlet port 3 and a

  input duct 4. In this illustration of a pre-

  In practice, the fluid inlet duct 4 is

  presented crossing the reaction zone through the center and has

  a length approximately equal to the diameter of this zone. Enjoyed-

  a plurality of fluid distribution conduits, which comprise an outer tube 5 and a smaller inner tube 6, are arranged below the inlet duct 4 and are located in

  a common plane that is perpendicular to a vertical plane con-

  holding the central axis of the inlet duct. As we have

  clearly shown in FIG. 2, the fluid inlet duct 4 communicates directly only with the internal distribution ducts 6, by means of reducing connections (or union connectors) 7. In the plan view of FIG. 1, the whole device occupies approximately

  80 / of the section of the catalytic reaction chamber 2.

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  Fig. 2 is an elevational view and partly in section taken approximately along line 2-2 of FIG. 1. The cooling fluid stream passes from the inlet duct 4 to the inner distribution ducts 6 by short vertical tubes 8, the reducing connections 7 and tubes 9; the tubes 9 are vertical and generally of the same size as the ducts 6. Two holes 6a offset by

  1800 relative to each other project the current of re-

  chilling on an imperforate part of the vent pipe

  external tribution 5 which has 4 holes 5a offset by 30

relative to the vertical axis.

  The relative positions in the space of the distribution ducts 5 and 6, as well as those of the holes Sa and 6a, are shown in FIGS. 3 and 4, which are drawn at

  larger scale for clarity. We also

  presented on these views a stabilizing disc 10 and the perforated screen 11 which surrounds the external distribution duct

  5. The jet effect of the cooling fluid exiting through

  to the holes Sa actually circulates the reagent stream through the holes 6a as would a pump and the coolant mixes intimately with this current thanks to the fact that it is projected against the non

  perforated outer conduit 5. The holes lla of the screen per-

  They are dimensioned to prevent particles

the catalyst to cross them.

  Fig. 5 is a side elevational view of the duct

  6 interior distribution system comprising the stabilizing discs

or washers 10. As indicated, the adjacent pairs

  such discs effectively separate the holes 6a

  one another. Fig. 6 shows more clearly the rooms

  In each case, the inner stabilizer disc 10a is mounted in the manner shown to deflect the current.

  cooling fluid passing through the tube 9 in such a manner

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  re that it travels the entire length of the conduit of

  6. Between the pairs of static discs

  bilisers are formed of stagnant areas 12.

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R E V E NT D I C A T IO N S

  1 - Fluid dispensing device for

  being mounted in a catalytic reaction chamber containing a fixed bed of catalyst particles, this device being characterized in that i comprises, arranged so as to cooperate

  together, (a) a fluid inlet duct (4), (b) a first

  first set of spaced fluid distribution perforated conduits (6) freely communicating with said fluid inlet duct (4) and disposed in a plane perpendicular to the vertical plane which contains the axis of the inlet duct (4);

  fluid, (c) a second set of perforated conduits (5) of

  tribution of fluid that have a nominal diameter larger than

  that of the first fluid distribution ducts, each

  each of these conduits being disposed coaxially and concentrically

  around a corresponding one of the said first conduits

of distribution.

  2 - fluid dispensing device according to claim 1, characterized in that said first and second fluid distribution ducts are arranged

  below said fluid inlet duct.

  3 - Fluid dispensing device according to one

  any of claims 1 and 2, characterized in that

  the perforations of the ducts of the second set have a diameter greater than that of the perforations of the ducts of the first set. 4 - Device for dispensing fluid according to one

  any of claims 1 to 3, characterized in that

  spaced annular stabilizing disks, the largest of which

  diameter is approximately equal to the inside diameter of the two

  xth distribution ducts surround the first

  distribution and are arranged approximately perpendicular

lair to the axis of these ducts.

  - Fluid dispensing device according to one

  any of claims 1 to 4, characterized in that

  each of the second distribution ducts is enclosed in

a perforated cylindrical screen.

  6 - Fluid dispensing device according to one

  any of claims 1 to 5, characterized in that

  the perforations of the second distribution ducts are chamfered inwards. 7 - Device for distributing fluid according to one

  any of claims 1 to 6, characterized in that

  the perforations of the first fluid distribution ducts are arranged so as to allow a projection

  against an unperforated part of the second

  tribution. 8 - fluid dispensing device according to claim 7, characterized in that the perforations of the first distribution ducts are arranged at 900 relative to the vertical axis and in that the perforations of the second distribution ducts are arranged at 300 by

relative to the vertical axis.

  9 - fluid dispensing device according to claim 4, characterized in that the successive pairs of stabilizing disks form, along the length of the first and second ducts, separate inner chambers

  each containing perforations of the first and second

xth distribution ducts.

  - Device for dispensing fluid according to the

  any of claims 1 to 9, characterized in that

  it occupies between about 60.0% and about 90.0% of the horizontal section of the reaction chamber.