US2653058A

US2653058A - Elevation of granular solids

Info

Publication number: US2653058A
Application number: US251975A
Authority: US
Inventors: Frank W Bowen
Original assignee: Sun Oil Co
Current assignee: Sunoco Inc
Priority date: 1951-10-18
Filing date: 1951-10-18
Publication date: 1953-09-22
Anticipated expiration: 1970-09-22

Description

p 2, 1953 F. w. BOWEN ELEVATION OF GRANULAR SOLIDS Filed Oct. 18, 1951 m I .m.

H I I HI I II N H In I/l Ill- FRANK w. BOWEN ATTORNEYS Patented Sept. 22, 1953 ELEVATION OF GRANULAR SOLIDS Frank W. Bowen,-Toledo, Ohio, assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application October 18, 1951, Serial No. 251,975

This invention relates to apparatus and method for pneumatically moving granular or pelleted contact material or catalyst from a lower receptacle into and upwardly through an elongate conduit to an upper receptacle. In particular the invention is directed to the supply of gas or air to the material in the lower receptacle in order to convey it therefrom to and through the elongate conduit in a particularly eflicient manner.

It is well known in the art of catalysis, such as the cracking of heavier petroleum fractions to gasoline and other hydrocarbon processing operations, to use a catalyst or contact material in a continuous system. In such continuous systems a conversion zone is operated simultaneously with a second zone which is in regeneration. Most commercial moving or continuous catalyst systems have the conversion zone and regeneration zone in superposed relationship with the'conversion zone usually above the regeneration zone so that the catalyst or contact material moves through the conversion zone to the regeneration zone by gravity and after regeneration it is carried upwardly and returned to the conversion zone to repeat the cycle of operation. To return the catalyst or contact material from the lower regenerating zone to the upper conversion zone two well known means applicable to the transportation of granular solids from one locus to another have been used, namely: by mechanical conveyors and by pneumatic conveyors, in the latter of which air, steam or flue gas produced at the refinery is readily available as the pneumatic lifting medium.

It is necessary in systems employing conversion and regeneration zones in superposed relationship to convey the catalyst or contact material through a conduit several hundred feet in length in order to return it from the lower reaction zone to the upper reaction zone. From the lower reaction zone the material. is delivered by gravity to a receptacle positioned at a level below that of the lower zone, from which receptacle it is necessary to effect or begin the lifting or upward conveying operation. In a pneumatic lifting system this lowermost receptacle is generally known in the art as an engager since the material is engaged therein by-the'lifting flue gas or air to effect the lifting operation. The lower end of the air lift conduit extends into or is in com- 7 Claims. (01. 302-57) munication with the engager receptacle while the upper end of the lift conduit communicates with an upper receptacle positioned at a level above the top of the upper reaction zone or chamber. The upper receptacle is designed so that the lifting medium is separated from the catalyst or contact material and is generally known as the disengager.

The present invention involves an arrangement for engaging material to introduce it to the lower inletend of th elevating conduit and maintaining it in a continuous stream through the conduit for passage to the disengager in a manner to reduce attrition of the material to a minimum.

A complete understanding of the present invention may be had by reference to the following description taken in connection with the accompanying drawings which form a part of the application in which:

Figure 1 is an elevational view for schematically showing a typical catalytic cracking system employing a pneumatic lift for elevating pelleted catalyst or contact material.

Figure 2 is an enlarged view in sectional elevation showing the invention as applied to the engager portion of the system.

Figure 3 is a sectional view taken on the line 33 of Figure 2.

Figure 4 is a sectional view taken on the line 4--4 of Figure 3 to show details of the invention.

Referring to Figure 1 of the drawing, which shows diagrammatically the conventional elements of a continuous system, a lower receptacle or chamber l0 functions as a catalyst engaging zone, that is, a zone wherein the catalyst is engaged by the air, flue gas or steam supplied thereto by suitable means. The lift pipe or elevating conduit is indicated at I l and has its lower end communicating with the chamber I0 and its upper end communicating with-an upper chamber l2 which is the disengaging chamber or zone wherein the material is disengaged from the air or other elevating medium. The lifting medium is discharged from the upper chamber l2 through a conduit l3 and is passed to any conventional separating means such as a cyclone separator I4 having an upper conduit I5 in communication therewith to remove the lifting medium and a lower conduit I6 for removing any fines which become entrained in the lifting medium.

The catalyst which remains in the disengager I2 is returned through conduit I! by gravity to an upper reaction chamber I8 wherein usually an on-stream reaction is effected to obtain the desired product and continues to flow therefrom through conduit H! by gravity into a lower reaction chamber 26 wherein the catalyst or contact material is regenerated to remove any deposits which might have been formed on the catalyst in the upper chamber l8. From the lower chamber 20 the catalyst or contact material continues to flow by gravity through conduit 2| and is returned to the engaging chamber Ill. The conduits l1, l9, and 2| through which the catalyst or contact material flows in returning from the disengager l2 to the engager are usually provided with means for supplying steam or other gaseous purging medium thereto in order to prevent reaction products formed in chamber l8 and regeneration fumes formed in chamber 20 from communicating with the other chambers in the unit.

Referring to Figures 2 and 3, the engager of the present invention is indicated generally at 30 and is made up of an inner elevating conduit 3| and an outer conduit 32 which is concentric with the inner conduit and provides a space 33 therewith.

Longitudinal partitions

34 and 35, shown clearly in Figure 3, are disposed between the conduits 3| and 32 to provide a passageway 36 for contact material which is admitted thereto by conduit 2| as explained in connection with Figure 1. A passageway 31 is also provided for receiving a-lifting fluid medium, for example, flue gas formed in regeneration zone 20 referred to in the description of Figure 1. The contact material that is supplied to the space 36 passes downwardly therethrough to an angularly disposed plate 38 over which the material passes to be engaged by the lifting medium supplied through conduit 39 to the passageway 31 and the contact material is moved to the inlet end 40 of the elevating conduit 3|. The

spaces

36 and 31 are closed at their upper ends by means of a ring 4| which is secured to the inner conduit 3| and the outer conduit 32 which additionally gives strength and rigidity to the structure. While element 32 is shown specifically as a cylindrical member it will be understood that it functions as a housing and may be of any desired size and shape within the scope of the invention.

The plate 38 is provided with an upstanding side wall 42 to lit in sliding engagement with the inner wall of conduit or sleeve 32 and a conduit 43 has its upper open end secured in the plate 38 in order to supply lifting fluid directly below the body of contact material, as it moves across the plate 38, to assist in elevating the contact material through the lower end 40 of conduit 3|. The conduit 43 is adjustably secured to a supporting member 44 by means of an adjusting nut 45 to permit the plate 38 and side wall 42 to be adjusted toward and away from the lower end 40 of the elevating conduit 3| in order to regulate the volume of contact material in zone S. As indicated in Figure 2 the partition 34 depend from ring 4| and extends to the lower end 40 of elevating conduit 3| and similarly the partition 35, although not shown in Figure 2, depends from ring 4| and extends to the lower end 40 of conduit 3| in order to prevent the elevating fluid in passageway 31 from by-passing directly into contact material passageway 36.

Referring to Figure 4 it will be seen that the

partitions

34 and 35 are slotted at 34' and 35' respectively to receive the side wall 42 and permit adjustment of the plate 38 relative to the lower end 46 of conduit 3| while preventin the escape of any of the lifting or elevating fluid supplied to the zone S.

The bottom of the wall of lift conduit 3| is cut off at an angle, so that all points on the bottom of the lift conduit wall lie in an inclined plane. As a consequence of this construction, the lift conduit 3| has a lower end 40 which extends downwardly to a lower level on the side adjacent the space 31 than the level to which the lower end 40 extends on the side adjacent the space 36 through which granular material is introduced into the zone.S. As a consequence, in passing from space 36 into zone S, granular material tends to form a bed having an upper surface, determined by the angle of repose of the material, which is closer to the lower end 40 of lift conduit 3| on the side where lifting gas in introduced from space 31 into zone S than in prior art apparatus where all portions of the lower end of the lift conduit are on substantially the same level. Thus, according to the present invention, lifting gas as it passes from space 31 around the lower end of the wall of lift conduit 3| and moves upwardly and laterally into the lift conduit is brought into closer contact with granular material in zone S than is obtained according to prior art operation wherein the level of the compact bed which the granular material tends to form is farther beneath the lift conduit inlet. The closer contact achieved according to the present invention increases the efficiency of the engaging operation and makes it possible to lift solids at greater rates in a given size of apparatus than can be obtained according to prior art operation involving the introduction of lifting gas through a sleeve around the lift conduit.

In operation, granular material gravitates through inlet line 2| and space 36 toward engaging zone S wherein it tends to assume its normal angle of repose and thereby form an upper bed surface which is adjacent the inlet of lift conduit 3| on the side of the latter which nearest to inlet line 2| and which surface is adjacent, at a lower level, to the lift conduit inlet on the side farthest from inlet line 3|. Lifting gas is introduced through line 39 and space 37 into lift conduit 3| at a location adjacent to the bed surface at the lower end of the lift conduit wall, the direction of flow of lifting gas being opposite to that of granular material, so that as'lifting gas passes upwardly and laterally through the zone S, it is adjacent the upper surface of the bed of granu lar material, sincethat upper surface is substantially parallel to the path followed in passing from the lowest level of the bottom of the lift conduit wall to the opposite highest level thereof.

It is to be understood that the upper inclined surface which the solids mass tends to form beneath and adjacent the lift conduit inlet is in operation generally disrupted by the action of lifting gas entraining solids from the surface of the mass, and the apparent surface of the mass is beneath the level at which it would be if such entrainment were not taking place. Nevertheless,

according to the invention, granular solids are According to the'invention, the bottom of the .lift conduit wall is at a lower level on a low side thereof than on the opposite, "high sidef'i thereof, and the angle with the'horizontal ofan imaginary line' between the lowest level of the bottom of the lift conduit wall and theopposite. highest level of the bottom of the lift conduit of repose of said granular solids. t .3. Apparatus according to claim 1 and addisolids and'lo degrees less the static angle tionallycomprising: longitudinal partitions sep-' arating said lifting gas supply area from said granular'solids supply area and having their wall is within the approximate range between 20 degrees greater than the static angle of repose of the, granular solids and degrecs'less than the static angle of repose of the solids. For example, if as shown-in Figure 2, the 'lower'end of Y the lift conduit is cut oil 'atan angle with the horizontal that angle is preferably not more than 20 degrees greater nor more than 10 degrees less than the static angle of. repose of the granular solids: more preferably the angle imabout 10 degrees greater than the staticangleof repose of the solids. J

The static angle of repose' of granular solids is a recognized property of such solids and is defined as the angle withthe horizontal assumed by the upper surface of a compact mass of such solids in a relatively expanded zone upon flowing from a relatively constricted zone into the relatively expanded zone. Y

According to the present invention, granular lower ends adjacent the bottom of the lift conduit -wa'll. 4 4. Apparatus according to claim 1 and additionally comprising: an inclined barrier spaced 7 beneath the bottom of thelift conduit wall at grees greater than said angle of repose, said baran angle within the approximate range 5-20 derier providing a lower boundary of saidengaging area. I

5. Apparatus for elevating granular solids which comprises: a substantially vertical lift conduit, all points on the bottom of the wallof said lift conduit lyingin a plane inclined at an angle with the horizontal'within the approximate range between ZOdegrees greater than the staticangle of repose of said granular solids and 10 degrees less than the static angle of repose of said granularsolids; a sleeve surrounding and spaced apart material andlifting gas can be supplied, re- 7 spectively, to the lowand high sides of -a lift conduit inlet through sections of a divided annular passageway, as shown in Figures 2, 3, and 4; or b any other suitable arrangement can be used for supplying granular material and lifting gas, re-' spectively to the low and h gh sides of a lift con-. duit inlet. 1

tageously be angularly disposed in order, to eliinifrom a lowermost portion of said liftconduit and extending above and below the bottom of the wall f of said lift conduit; atop plate secured to the top of said sleeve and having an aperture therein in which said lift vconduit is secured; two" longitudinal partitions each secured to said top plate and to the wall of said sleeve and to the wall of said lift conduit, and each having its lower end adl The plate 38 as shown in Figure 2,.can advannate or minimize the amount of stagnant solids in the apparatus, but any other suitable means forclosing off the lower'part ofthe apparatus can be used; if the plate is angularly disposed,

the angle with the horizontal is preferably within the approximate range 5- 0 degrees,,more preferably 10 degrees, greater than the static'angle of repose of the granular solids. Also,.the use of an auxiliary lifting gas supply through line 43 is optional according to the present invention.

The invention claimed is:- 1 1. Apparatus for elevating granular solids which comprises: a liftconduit having the bottom 'of its wall at a lower level on a low-side thereof than on the opposite side, or flush side," thereof; a housing surrounding and spaced from.a lower-. most portion of said lift conduit and providing an engaging area beneath and communicating with the lift conduit inlet and providing a-lifting gas supply area adjacent and outside said lowermost portion of said lift conduit on the low side thereof and a granular solid supply area adjacent and outside said lowermost portion of said lift conduit on the high side thereof, both of the supply areas communicating with said engaging. area;

- means for introducing lifting gas into said lifting.

gas supply area and thence into said engaging area; and means'for introducing granular solids into said granular solids supply area and .thence into said'engaging area.

2. Apparatus according to claim 1 wherein the angle with the horizontal of an imaginary line' between the lowest-level of the bottom of the lift conduit wall and the opposite, highest level of. the bottom of the lift conduit wall is within the approximate range between 20 degrees greater than the static angle of repose .of said granular jacent said planeand .on a substantially horizontal axis of said lift conduit, said partitions being on opposite sides of said lift conduit-from each other and providing a lifting gas supply chamberabo've the lower side of the bottom 61' the lift conduit wall and providing-a granular solids supply chamber above the higher side of the bottom of the lift conduit wall; a lifting gas conduit communicating with said lifting gas supply chamber; a -"granular solids conduit communicating with said granular solids supply chamber; a plate spaced beneath the bottom of the wall of said lift 'conduitand inclinedat an angle with the horizontal about 5-20 degrees greater than the static angle of repose of said granular solids, and defining the lower boundary of an engaging area communicating with said lifting gas supply chamberand said granular (solids supply chamber; a conduit section having its lower end secured to said plate andhaving its upper end in .slidable relation with the lower end of said housing and a second lifting gas conduit substantially coaxial with. said lift conduit and having its upper end secured within an aperture in said plate.

- the lift conduit which communicates with an 6. Apparatus for elevating granular solids which comprises a lift conduit, a housing surrounding the lower end portion of the lift conduit having a closed upper end with aclosed lower end depending below the. lower inlet end of the lift conduit, said housing providing a space about engaging area below said inlet end of the lift engaging area in a manner to pick up and elevate the granular material through the lift conduit.

7. Apparatus for elevating granular solids which comprises a lift conduit, a housing surrounding the lower end portion of the lift conduit having a closed upper end with a closed lower end depending below the lower inlet end of the lift conduit, said housing providing a space about the lift conduit which communicates with an engaging area below said inlet end of the lift conduit, means dividing said space into independent chambers, means for supplying granular material tonne of said chambers tor passage downwardly into said engaging area and means for simultaneously supplying elevating fluid to the other chamber for passage downward- 1y into the engaging area into a zone thereof below the zone or entry of the granular material and said elevating fluid then passing upwardly or the engaging area in a manner to Pick up and elevate the granular material through the lift conduit.

FRANK W. BOWEN.

References Cited in the file Of this patent I UNITED STATES PATENTS Number Name Date 528,417 Duckham Oct. 30, 1894 1,549,285 Baker Aug. 11, 1925 2,433,726 Angell Dec. 30, 1947 2,561,771 Ardem July 24, 1951