FR2582955A1 - Rotary device for distributing divided solids - Google Patents

Abstract

The rotary device for distributing divided solids according to the invention comprises a rotary shaft 1 of axis X-X, to the lower end of which is secured, perpendicularly to this shaft, a tray 2 fed with solid particles in its central region, divided into a plurality of adjoining sections 20a, 20b, ... 20n, of quadrangular overall shape, with surfaces which are unequal and symmetrical in pairs in relation to the axis X-X, separated from one another by blades 3a, 3b ... 3n of substantially radial directions and unequal lengths lying above the tray 2, perpendicularly to the latter. Application to the uniform distribution of divided solids over an entire horizontal section of a column used especially for producing contact between the divided solids and a vertical upward gas stream.

Description

The present invention relates to a particle distribution device

  solids intended to ensure the uniform distribution thereof on a flat horizontal circular surface, for example the upper circular surface of the packing area of a cylindrical column of solid / gas contactor. In devices with direct contact between solids and gases, where physical and / or chemical modifications of the solids and / or gases are carried out, the main problem is to obtain a uniform distribution of solid particles in the section of the enclosure which may or may not be fitted with devices facilitating contact between the solid particles and the gas, so as to ensure the most homogeneous contact

possible in the device.

  For solid particles whose geometry is not too far from that of the sphere and whose particle size is fairly homogeneous, a number of solutions have been proposed which are satisfactory. We will cite for example distributors with arms

  turning points supplied with solids by an upper fluidized bed.

  On the other hand, for solid particles with a fairly dispersed particle size and the shape of which is that of platelets, that is to say one of the dimensions (the thickness) is much less than the other two dimensions (the width and the length ) or solids in

  needle shape where one dimension (length) is clearly greater than

  lower than the other two, the aforementioned systems are ill-suited.

  In fact, platelets or needles are very different forms

fluidly fluidizable.

  Solid particles of large particle size (several mm) and those of high specific mass are also difficult to fluidize, these non-fluidizable products belonging to class D

of the GELDART classification.

  In addition, in many cases, we do not wish to introduce gas

  flow in the distribution system. This fluid gas

  sation can cause an unwanted action (dilution, chemical action on another component, change in temperature, etc.) unless the same gas circulating in the device is used as the fluidizing gas, which must therefore be conditioned for this usage,

  an operation which is not always easy to perform.

  The device which is the subject of the invention makes it possible to provide repair-

  regular or uniform tition of the solids throughout the circular section of a direct solid-gas contact device, whatever the shape of the solid particles, that is to say in the case where all or part of these solid particles has a geometry close to that of the pads or needles and also in the case where the

  solid to be distributed is a mixture of one or more bodies to be treated -

  often of any geometry - with a body not undergoing chemical modification such as a coolant - often of geometry

regular close to the sphere.

  A regular distribution of solid particles in the section of a device in direct contact between said solids and a gas or a mixture of gases is therefore carried out using the device according to the invention. The present invention thus relates to a rotary distribution device for solid particles rotating around a vertical axis XX, with a view to ensuring the regular (or uniform) distribution of said solid particles over a whole horizontal section of a column of axis XX, in particular the upper circular surface of the

  packing area of a cylindrical column of a gas contactor

  solid, which consists of a rotary shaft of axis XX, at the lower end of which is fixed, perpendicular to this tree, a plate, fed with particles in its central area divided into a plurality of contiguous portions of generally quadrangular shape , of unequal surfaces, and symmetrical two by two with respect to the axis XX, separated from each other by blades of substantially radial orientation and of unequal lengths, extending above the plate

perpendicular to it.

  Thanks to this arrangement, it is possible to distribute homogeneously throughout the section of a device in direct contact with solids-gas, a solid or a mixture of solids which can be fluidized or not.

  and / or that one does not wish to fluidize in the dispenser.

  The invention also makes it possible to save costs on construction by reducing the mass of the device and reducing maintenance costs by reducing the number and simplifying the rotating parts. _

- 258295-S

  ............................................ DTD: 3 -.

  The present invention will be better understood on reading the

  description which will follow, with reference to the accompanying drawings given to

title of examples, on which: .. '

To, To: ...

  - Fig. 1 is a perspective view, - with partial cutaway, -

  of a first embodiment of the distribution device. of

  solid particles according to the invention; .. -'--

  - Fig. 2 is a sectional view of the device shown in the a

  Fig. 1, along a vertical radial plane -...

  - Fig. 3 is a sectional view taken along the horizontal plane, .-

  passing through line III-III of FIG. 2 '; -

  - Fig. 4 is an elevational view of the front half, with respect to the line IV-IV of FIG. 3, of the lower part of the device shown in FIG. 2; - Fig. 5 is a perspective view, with partial cutaway, of a second embodiment of the device for dispensing:

  solid particles according to the invention ,.

  - Fig. 6 is a sectional view, along a vertical radial plane, of.

  device shown in FIG. 5; '.

  - Fig. 7 is a sectional view taken along the horizontal plane,

  passing through line VII-VII of FIG. 6; '.

  Fig. 8 is an elevational view, on a larger scale, of the lower part of a variant of the device shown in FIG. 4; - Fig. 9 is a schematic view, in section, along a vertical radial plane of the device according to the invention, allowing.-to explain '

operation .; - ..

  - Fig. 10 is a schematic top view of the device

shown in Fig. 9. '- - ..

  In Figs. 1 to 4 is represents a first realization of the

  dispensing device according to the invention.

  A vertical tree 1 ,. of axis XX, 'driven by a motor system (not' shown), drives in rotation a rotating assembly consisting of a plate 2, orthogonal to the axis XX of the shaft 1, divided radially or substantially radially into a plurality of portions of unequal radius by blades 3a, .3b, 3c, ... 3n (here at-number-of-fourteen)

  implanted orthogonally to the surface of the plate-2 and. linked between - -

  they, at their upper part closest to the axis of rotation, by a ring 4 whose lower end is separated from the plate 2 by a spacing H (Fig. 2) so that one spares between this ring 4 and the plate 2 of the openings 5a, 5b, ... 5n, of which only the opening 5d is visible in FIG. 1-, for the passage of solid particles to be distributed. The plate 2 is divided into fourteen portions 20a, 20b, 20c, ... 20n, delimited by two consecutive blades of unequal lengths. The blades are symmetrical two by two with respect to the X-X axis, and therefore constitute two groups

  identical each occupying a half-circumference of the plate.

  Some of these blades 3b, 3c and 3d (see Fig. 1 and 4) which are consecutive are extended below the plane of the plate 2 and correspond to portions 20b, 20c and 20d whose average radius is

lower than that of ring 4.

  Each portion is formed by a part of the plate 2 of quadrangular shape, bounded radially by two consecutive blades and, for the other two sides, on the one hand, by a portion of a circle on the side of the axis XX corresponding to the inner edge of the plate 2, defined below, and, on the other hand, on the outside by a line segment. For the portions whose mean radius is greater than that of the ring 4, this straight line connects the lower edge of the outer ends of the two blades. For the portions whose mean radius is less than that of the ring 4, the line segment connects in the plane of the plate 2 the inner ends of the two blades

  which, in this case, are extended below the plane of the plate 2.

  Between these two types of portions, the transition portion is externally limited by a straight line joining the lower edge of the outer end relative to the ring 4 of the longer 3rd of the two blades at the inner end of the shorter 3d, in the

plate plan 2.

  As shown in Fig. 3 the fourteen portions of the distributor 20a to 20n constitute two groups of seven symmetrical portions with respect to the axis of rotation. In each group, three portions have mean radii smaller than the radius of ring 4 and there

  corresponds to the blades extended under the plate 2.

  Above the rotating assembly consisting of the shaft 1, the plate 2 and the blades 3, a fixed cylindrical duct 10, of axis XX, concent-rntque - rl 'rbre-4! .- household-un -es-pace-_annulaire 1Aa for the descent of solid particles with a cylinder 12, or wear sheath, integral in rotation with the shaft 1. The wear sheath 12 corresponds to

  the inner limit of the contiguous portions defined on the plate 2.

  The conduit 10 receives on one side a conduit 11 for supplying solid particles connecting to the conduit 10 at an angle allowing the flow of the particles. Below the connection of the supply duct 11 to the duct 10, the wear sheath 12 carries a plurality of blades 13 in the form of a helicoid portion distributed over the circumference of the sheath 12 which can sweep the annular space

  lOa defined by the conduit 10 and the sheath 12.

  The wear sheath 12 is positioned concentrically with the shaft 1 by two series of fingers 14 respectively disposed at the upper and lower ends of said sheath. The sheath 12 rests on the bottom 15 of a ferrule 16, concentric with the shaft 1, the bottom 15 being fixed to the lower end of the shaft 1. The ferrule 16 itself supports the distribution plate 2. In known manner, the wear sheath is locked in rotation relative to the shaft 1 by dishes, not shown, carried by the bottom 15 cooperating with conjugate slots formed in the wear sheath 12 at its end

lower.

  The plate 2 of the dispenser carries a ferrule 21 which engages in the annular space between the wear sheath 12 and the ferrule 16 carried by the shaft 1. The rotation lock is obtained by the cooperation of the fingers of centering 14 of the wear sheath with

  notches 22 formed at the base of the ferrule 21 FIG. 4.

  According to an alternative embodiment shown in FIGS. 5 to 7, the supply of solid particles can be carried out using a

fluidized bed siphon.

  A vertical shaft 1 rotates a distribution plate

  bution formed by portions of different sizes 20a, 20b, ... 201, distributed in two groups of six symmetrical portions with respect to the axis of rotation, delimited by blades 3a, 3b, ... 31 located perpendicular to the plane of the tray and on the upper surface thereof, as well as a conduit 40 concentric with the shaft 1 which widens

  at its upper part in funnel 41.

  The duct 40 integral with the blades stops at a certain height above the plane of the plate thus providing openings 5a, 5b,

  51 for the passage of solid particles.

  The distribution device is located in the axis of the

  gird 0l0 where the solid-gas contact is made. This cylindrical enclosure 100 widens at its upper part into a concentric enclosure 110 with a diameter greater than that of the part 10O, thus providing an annular surface 50 for connection between the

two ferrules.

  A sector of this annular surface 50 is occupied by a fluidized bed 55 delimited by a wall 51 in the form of a portion of cylinder concentric with the wall of the enclosure 110 and substantially in the

  extension of the wall of the enclosure 100, and by two side walls

  52 radial planes. The upper part of the wall 51 is connected to a frustoconical surface 53 forming a weir which

  ends above the funnel 41 extending the conduit 40.

  The bed 55, supplied with solid particles by the pipe ll opening into the wall of the enclosure 110 inside the bed, is fluidized by a fluidizing gas distributed by the pipe 54

  with adequate holes or slots.

  Line 54 is supplied with fluidizing gas by a

conduct not shown.

  The two groups of six unequal portions 20a, 20b, ... 201 and more especially the two portions 20a and 20g are characterized by the presence on each of them FIG. 7 of a plate 23 closing them at their end between the corresponding blades 3a and 3b and 3g and 3h respectively. This plate 23 is perpendicular to the plane of the portion which then has a circular orifice 24 for the passage of solids. This orifice is therefore formed inside the envelope

of the ring 40.

  Of course, in this simpler embodiment, the supply conduit 40, integral with the axis 1 and the distribution disc 2, can be placed in a column of constant diameter, the fluidized supply bed of the distributor being located for example

outside the column.

  Another variant of the first embodiment of the

  distibutien-represented-in Figs-3-and 4-is-represented-in-Fig. 8.

  .1o One finds there the same constitutive elements assigned the same numerical reference marks as in 4, this alternative embodiment differing by the presence on the plate 2 of an annular zone 26 concentric with the axis XX of the device, limited inside by the diameter of the ferrule 21 and extending outside up to a radius

  less than the radius of the shortest portion. Said area -

  annular, the bottom of which is located below the level of the ends of the portions of the plate 2, constitutes a retention capacity 25 or reservoir for the solid particles flowing on the plate. The

  bottom of this capacity 25 can be. flat with a connection surface

  annular with the portions of plate 2 as illustrated in -

  Fig. 8, or the capacity 25 may consist of a crown-of

spherical cap.

  The operating principle of the distribution system-

  of solid particles according to the invention is shown in the

Fig. 9 and 10.

  A vertical tree. 1 of axis X-X drives in rotation, according to the

  direction of arrow f, a substantially horizontal plate 2.

  composed of a plurality of portions of different radii delimited by blades implanted perpendicular to the surface of the plate 2. These blades can be strictly radial or be located in a plane forming a small angle, for example less than 150, with the

corresponding radial plane.

  Each portion is delimited by two blades, only one of them -

  them, the one that is numbered on the drawings, being-functional-

  Lately active for the distribution of solids passing through the sector. It is the one that is located behind the direction of rotation. In Figs. 9 and 10, the number of portions has been reduced to two for reasons of simplification: a portion of radius Rl delimited

  by the blade marked 3a and a portion of radius R2 delimited by the -

  blade 3i. The solid particles S are brought to the plate 2 by the annular space delimited by the shaft 1 and the tubular conduit 40 concentric with the first and integral with the blades 3a, 3i on a part

of their height ..

  The solid particles S can flow gravitatively on the portions of the plate-2-thanks-to-open-res 5a, 5i- prat-iques dan, the tube 40 between the two blades which delimit the sector. There are two cases of flow depending on whether the radius of the sector is greater than the outer radius Re of the annular space for supplying solid particles. In the case where the radius R2 is less than Re, the solid particles pass, on the one hand, directly through the annular space between R2 and Re and, on the other hand, through the opening 5i. The centrifugal force presses them against the blade 3i which is then usefully extended, on the one hand, according to the radius beyond the RZ value and,

  on the other hand, of a certain height F below the level of the plate 2.

  This arrangement has the effect of imparting an impulse to the solid and of separating the jet of solid particles from the other jets of the

adjacent portions.

  The trajectory of the solid particles leads to watering an annular sector of average radius: V2 and of width L2 on the horizontal plane PP which corresponds to the upper circular surface of the packing zone of the column. A flat blade such as 3i does not allow watering a plane such as PP in an annular sector of average radius less than R2. On the other hand, if a concavity (not shown) directed towards the axis of rotation X-X is formed in the lower part of the blade, the solid particles are brought back towards this axis and this ensures a distribution of the solid particles in the

central area of the plan to be watered.

  The concavity is advantageously obtained by torsion or by folding of the part of the blade extended by a height F below the plane of the plate 2. The part deformed by torsion or folding must have its concavity directed towards the axis of rotation XX and the deformation is

  performed in front of the blade relative to the direction of rotation.

  In the case where the radius R1 is greater than Re, the solid S flows along the blade 3a to the outer end of the blade 3a and it is projected along a trajectory which leads it to water an annular sector of average radius V1 and of width L1 on the horizontal plane PP. The equation of the system leads to a relation of the type: Vx = a. N. Rx.cos (D) + bo Vx = average radius of the solid falling out of the blade of radius Rx on a plane located at dimension Z below the plate, N = speed of rotation of the distributor in revolutions / min , Rx = radius of the blade of index x, D = angle of the blade with the radius at its end, a and b = constants depending on the characteristics of the solid and the distance from the plate to the surface to be watered Z. We can therefore see that , by a judicious combination of the number of portions and their radius and by varying the speed of rotation, it is possible to uniformly distribute solid particles over a

  given area of a solid-gas direct contact system.

  The flow of solid particles that can be distributed depends on the size of the annular supply space, the height H of the openings formed between the distributor plate and the base of the

  supply duct and rotational speed.

  The exemplary embodiments below present the characteristics and performances of two solid particle distribution devices according to the invention, differentiated by the systems

  supply of solid particles.

- Example 1:

  We want to recover the thermal energy contained in ash from coal shales after combustion using a heat exchanger

direct solid-gas contact.

  The exchange is carried out in a cylindrical contactor whose internal diameter is 3.25 m. The shale, whose particle size is between 0 and 16 mm and the temperature is 950 C, is

  distributed by a device according to the invention such as that shown

felt in Figs. 1 to 4.

  The largest diameter of the distribution disc which has 24 portions is approximately 800 mm. It is gravity-fed with solid and allows regular distribution of 8 to 18 t / h of shale for rotational speeds between 30 and

Rotations per minute.

  A test at ambient temperature makes it possible to distribute 18 t / h of shale on a circular surface with a diameter of 3.25 m situated 700 mm below the distribution plate rotating at 77 revolutions / minute with a dispersion of less than 20%. We have

  measured the thickness of shales deposited during a given time.

  This value of the dispersion is to be compared with the values of the dispersions recorded with known devices where it can exceed 100%.

- Example 2:

  We want to feed a gas-solid exchanger to crack the tars

  produced by the pyrolytic decomposition of ligno- wastes

  cellulosics in a fluidized bed of sand at 900-950 C brought to

  O10 this temperature in another part of the installation.

  The cylindrical contactor has an internal diameter of 0.75 m and the sand with an average particle size of 0.55 mm is distributed by a device according to the invention such as that shown in

Figs. 5 to 7.

  The largest diameter of the distribution disc which has

  twelve portions, is about 270 mm. It is powered by overflow

  dement of an upper fluidized bed in sand with a flow rate of 4 to 12 t / h for rotational speeds between 30 and

Rotations per minute.

  A test with sand at 930 C exchanging with a counter-current of air showed that the heat exchanges (in terms of power) were improved by 10 to 15% by using the distribution system according to the invention compared to a static distributor. The sand flow was close to 8 t / h and the speed of

rotation of about 80 revolutions / minute.

  In the case where the solid particles to be dispensed consist wholly or in part of substantially spherical particles, of relatively high density and of high hardness, with the dispensing devices as they have been shown in FIGS. 1 to 7, the fall of these particular solid particles can give rise to rebounds on the surface of the plate 2, rebounds which can disturb the regularity of the distribution of the solid particles. The variant of the distribution disc shown in FIG. 8 with the retention volume 25 serving as a reservoir for the solid, the fall of which is then absorbed by a bed of the same material of a certain thickness, regulating

  thus the flow passing through the portions.

  ll ': Such an achievement gave full satisfaction for the distribution

  of a solid consisting of zircon beads of 1.2 mm in diameter.

  The production of a device for distributing divided solids according to the invention can call upon different techniques as well as different materials according to "the conditions of use. The rotating assembly can be produced by mechanic welding or by molding, by example: For use at high temperatures

  (more than 500 C), the use of refractory steels gives good - "

results.

-12 _

Claims (9)

  1.- Rotary distribution device for solid particles rotating around a vertical axis XX, in order to ensure the regular distribution of said solid particles over a whole horizontal section of a column of axis XX, in particular the upper circular surface of the packing area of a cylindrical column of a gas-solids contactor, characterized in that it consists of a rotary shaft (1) of axis XX, at the lower end of which is fixed, perpendicular to this tree, a plate (2), fed with particles in its central zone, divided into a plurality of contiguous portions (20a, 20b, ... 20n) of generally quadrangular shape, of unequal surfaces, and symmetrical two by two by relative to the axis XX, separated from each other by blades (3a, 3b ... 3n) of substantially radial orientation and of unequal lengths, extending above the   plate (2) perpendicular thereto.   2.- Device according to claim 1 characterized in that the blades (3a, 3b, ... 3n) are secured, by their end closest to the axis XX, a ring (4-40) similarly axis than the shaft (1) and whose inner diameter is larger than the outer diameter of the shaft (1), the lower end of the ring (4-40) being separated from the upper surface of the plate ( 2) by a spacing (H), this spacing (H) and two consecutive blades providing openings (5a, 5b ... 5n) through which the solid particles can flow   from the central zone of the plate (2) towards its periphery.   3.- Device for distributing solid particles according to   claims 1 or 2 characterized in that the blades (3a, 3b ...), the   shorter corresponding to the portions (20a, 20b ...) of the plate (2).   4.- Device according to claim 3, characterized in that the extension of the shortest blades (3a, 3b ...) below the plane of the plate (2) has a concavity directed towards the axis of rotation X-X.   5.- Device for distributing divided solid particles   according to claims 1 or 2 characterized in that the portions the   shorter of the plate (2) are closed at their outer edge by a plate (23) substantially perpendicular to the plane of the sector portion, the flow of solids taking place through a circular orifice (24) provided in each portion.   6.- Distribution device for divided solid particles   according to any one of claims 1 to 5 characterized by the   presence of a wear sheath (12) integral in rotation with the shaft (1) and concentric thereto, delimiting with the vertical conduit for supplying solids, which can be fixed (10) or integral in rotation (40) of the shaft (1) and plate (2) assembly, an annular space for the descent of solids, the wear sheath (12) advantageously carrying distribution blades (13) in the form of a helicoid ensuring the   regular distribution of solids in the particular annular space   in the case where the duct (10) is fixed and the supply of solids is asymmetrical.   7.- Device for distributing divided solid particles   according to any one of claims 1 to 6 characterized by the   fact that the supply of solid particles consists of a pipe (11) opening laterally into the annular space for the descent of said solids, above the blades (13) carried by the   wear sheath (12) if these exist.   8.- Device for distributing solid particles according to one   any one of claims 1 to 6 characterized in that   the supply of solid particles is constituted by an overflow fluidized bed system, said fluidized bed being located either inside or outside the column of the gas-solids contactor, discharging the solid particles into the upper part. of the annular space for the descent of solid particles, this upper part advantageously being in the form funnel (41).   9.- Distribution device for divided solid particles   according to any one of claims 1 to 8 characterized by the   fact that the plate (2) of the rotary distributor has in its central part between the shaft (1) and the radius of the inner end of the blades (3a, 3b, ...) an annular zone (26) whose bottom is located below the level of the ends of the portions (20a, b ...), constituting a retention volume (25) or reservoir for the   solid particles flowing over the plateau.