1. IN A GAS-SOLIDS CONTACTING VESSEL ADAPTED TO CONTAIN GRANULAR MATERIAL AS A FIXED BED HAVING AN EXPOSED SURFACE OF SUBSTANTIALLY GREATER LENGTH THAN WIDTH, SAID VESSEL HAVING A CIRCULAR GAS INLET NOZZLE ARRANGED TO INTRODUCE GASEOUS MATERIAL AS A DOWNWARDLY DIRECTED, HIGHVELOCITY STREAM CENTRALLY ABOVE SAID SURFACE OF SAID BED AND A GAS OUTLET ARRANGED TO DISCHARGE SAID GASEOUS MATERIAL AFTER PASSING DOWNWARDLY THROUGH SAID BED, THE COMBINATION THEREWITH OF A GAS DEFLECTOR COMPRISING A FLAT HORIZONTAL PORTION AND RAISED SIDE PORTIONS EXTENDING ALONG TWO OPPOSITE SIDES THEREOF TO FORM A SHALLOW U-CHANNEL PARALLEL TO THE LONGEST HORIZONTAL AXIS OF SAID SURFACE, THE BASE OF SAID CHANNEL HAVING A MINIMUM HORIZONTAL DIMENSION OF AT LEAST ABOUT 11/4 TIMES THE DISCHARGE DIAMETER OF SAID INLET NOZZLE AND BEING SPACED AXIALLY THEREBELOW A DISTANCE OF ABOUT 1/3-1 TIMES SAID DIAMETER, AND THE SIDES OF SAID CHANNEL HAVING A HEIGHT OF ABOUT 1/4-1/3 TIMES SAID DIAMETER AND A LENGTH OF AT LEAST ABOUT 1/3 OF SAID DIAMETER.
Feb. 16, 1960 J. KAzMn-:RczAK ET AL 2,925,331
GAS DEFLECTOR FOR GAS-SOLIDS CONTACT APPARATUS Filed Dec. 4, 1956 2 Sheets-Sheet 1 Feb- 15, 1960 L. J. KAZMIERCZAK ET AL 2,925,331
GAS DEFLECTOR FOR GAS-SOLIDS CONTACT APPARATUS FiIxLed Dec. 4, 1956 l 2 Sheets-Sheet 2 Z2 .a5 fz INVENTORS.
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Lu Evadez'idf Wullimzg United States Patent-O GAS DEFLEcToR FOR GAS-soups coNTAcr APPARATUS Leon J. Kazmierczak,'-Philadelphia, and FrederickA W. Sullivan lll, Wallingford, Pa., assgnors to Houdry Process Corporation, Wilmington, Del., a corporation of Delaware -Appiicagnnecember 4, i956, serial No. 626,240
6 claims. (ci. 2st-28s)A This invention relates to improvements in gas-solids contact apparatus of the type adapted to contain axed bed of coarse granular contact material through which gaseous material is made to ow downwardly for the purpose of carrying out a desired treatment of either the solids or the gas. More particularly the invention relates to an improved deilector for diverting gaseous material introduced at high velocity above the fixed bed, so that its velocity upon initial contact with the surface of the inlet nozzle. To protect such surface region of the bed, as well as the peripheral regions, various expedierits, such as a system ot grids and screens placed on top of the catalyst, `have been employed. *lhey have the disadvantage, however, of being complicatedr in design and expensive to fabricate, and they are likely to interfere or make dili'icult the charging and discharging of the granular particles comprising the bed during turnaroundpe-V riods. i
lri accordance' with the present invention, direct im-l pingement upon the-centralsurt'ace of the bed is avoided, and relatively uniform distribution' of the gas over the entire exposed surface of the bed is effected, by providing a detlector or batlie member which is supported abovev the surface of the bed, and spacedaxially below the gas inlet. The deliectoi or baii'1e, comprises a horizontal s plate'member,` somewhat larger than the discharge diameter of the gas inletfor nozzle, provided with upturned side portions at opposite sides of the baule which extend in ak direction generally parallel to the side walls of the reactor vessel. The deliector may comprise a single horizontal plate member which deliects all of the incoming gas stream, or'it fmay lcomprise a vertical series of spaced plate members, all but'the lowermost of which are centrally perforated, so that the downwardly directed gas stream in passing through the openings has an equal amount of gas deflected at each level. ln `such arrangement each plate has upwardly extending side portions generally parallel to the vsides of the vessel.
'In one formv of the invention the deectoi' comprises a rectangular' plate Amember having upwardly extended portions along two opposite sides, such portions being A typical dehydrogenation unit may comprise a plurality of such reactors arranged to operate continuously on repeated cycles of reaction and regeneration, with intermediate periods for evacuation, purging and catalyst reduction, all of which may be controlled in suitable manner by conventional time-cycle control apparatus.
=In such type of reactor the velocity of the incoming gas stream, particularly when air is being introduced in large quantity `during the regeneration cycle,'may be at such high velocity that its direct impingement against the surface of the compact bed will cause excessive turbulence and churning of the4 catalyst, with particles being scattered from the central to the peripheral surface regions of the bed. In AorderY to overcome such tendency it has been a practice to place upon the surface of the compact mass of granular catalytic material a protective covering of larger-size particles of inert material, such as alumina, which may be irregular in shape or be in the form ofspheres or balls up to about 3A inch in diameter, or even larger. L
The purposeof Vthe covering layer of Alarge-size inert material is toprevent the disruption of the catalyst mass by reason of the jet effectr of the high velocity air stream directed downwardly over a small surface area of the catalyst mass. It has been found, however, that despite the protective covering of the catalyst mass with a layer of large-size :inert granular material the `dimensional requirements oflthe reactor and the volume requirements of its gas supply means are such that it is extremely difficult to introduce the incoming gas inthe desired amount without the danger of exceeding tolerable velocity limits, thereby causing turbulence and disruption of the mass of granular material comprising the bed.
When the incoming gas streamis discharged downwardly through the top cylindrical wallofthe'reactor vessel normal to its axis and substantially midway between its ends, the region ofthe bed requiring maximum protection is that portion ofitssurface located centrally within thereactor and beneath the .discharge endof the f 'parallel to the' sides of the vessel. In another form of theinvention the dellector comprises a vertical series of four circular plate members or. disks spaced from each other about ,1A of the gas inlet'diameter. The upper three disks have a central lopening sized so that equal peripheral portions of the downwardly owing gas stream will be' intercepted and deflected at each level. In other words, approximately one fourth of'the total gas volume is intercepted at each level. To obtain such distribution of gas flow the openings in the Aupper three plate members must berespectivelyabout 7/8, 7/10, and 1/2 ofthe gas inlet discharge diameter. If more or fewer perforateplate members are employed, the relative magnitude of their opening diameters will of course be diierent. The disks may allbe ofthe same size or may be reduced in size as the openings get smaller. i i j Witli` respect to theA upturned side portions of the dellector plates, in the'case of the single rectangular plate y member the upturned opposite sides may suitably extend the full length of the plate member, whereas in the case of the annular plate members the uptiirned side portions of each circular disc or plate member is arcuate in horizontal projection' and is considerably shorter than the disc diameter, preferably not more than abouti/sthe discharge diameterlof the inlet pipe or nozzle.
`For Vay fuller understanding of the invention reference may be had to the following specilication and claims taken in connection with the accompanying'drawing showform of deflector channel ICC." Patented Feb. i6, i960 1 Fig. 5 shows in isometric view another form of deector adapted to channel the ow of incoming gas axially toward the ends of the cylindrical reactor;
Fig.r 6 is a plan view ofr the annular disc deector shown in. Fig. 5; and
Fig. 7 is a section taken` along line 7 7 of Fig. 6.
Fig. l of the drawings shows a cylindrical reactor of the type to which the deector apparatus of the present invention may be applied. `For the purposeof illustrating and describing one of the various applications of the invention, a reactor vessel 11 adapted to carry out a hydrocarbon dehydrogenation reaction by passing the hydrocarbons downwardly through a fixed bed of catalytic material supported centrally within the vessel has been selected. The catalyst is periodically. regenerated by discontinuingy the flow of, hydrocarbons',` purging, andv then passing air downwardly` through the bed to remove by combustion the carbonaceous material deposited upon the catalyst particles during the hydrocarbon conversion reaction. Separate withdrawal ofA they converted 'hydro'- carbon vapors and of the gaseous products of. regeneration are effected at the bottom of the reactor vessel, as will presently be described.
The reactor vessel is not shown in great, detail since, by itself, the vessel forms no part of the present. invention. The side of thevcssel has conveniently beenbroken away to clearly show the location of the catalyst. bed, the arrangement of the gas deector element and the location of the gas inlet nozzle with respect thereto.
Reactor vessel 11 is of conventional design, compris.- ing a cylindrical body portion with dished heads closing the ends. The vessel is set in a horizontal position and arranged so that the general direction of gas dow will be normal to its axis. v
The lower region of the vessel is provided with a supporting structure, such as a ceramic arch, not shown, horizontally surfaced with a layer of perforated tiles 12 extending across the entire vessel 11 at a level sufficiently below the axis thereof so that a fixed bed of catalyst of the desired depth may be provided substantially throughout the central region of the vessel.
For reasons hereinafter appearing, the catalyst is sandwiched between layers of other granular material. The bed of stratified granular material resting upon the surface of the perforated tiles 12 comprises a thin bottom layer of inert alumina balls 13 of about 1/2" diameter. Alumina balls 13 are larger than the perforations in the tiles 12 and are preferably of such size as to impose a minimum pressure drop for gas flow into and through the tile perforations. that there is a minimum of stoppage of the tile passageways by the alumina balls.
Immediately above the layer of 1/2" alumina balls there is a second layer of alumina balls 14 of about 1A" diameter. Above the layer 14 there is a relatively thick bed 15 of granular catalyst suitable for carrying out the desired dehydrogenation reaction. While the depth of catalyst bed 15 is substantially greater than that of the combined layers of alumina balls 13 and 14, with respect to its horizontal expanse it is a comparatively shallow bed. The catalyst bed 1S is of substantially uniform depth throughout, so that it has a ilatv horizontal surface. Spread upon the surface of the catalyst there is a covering layer of alumina balls 16 of about the same size as the alumina balls comprising the bottonnnost layer 13. The purpose of the covering layer of relatively large balls 16 is to prevent any disruption of the surface of the catalyst bed as a result of high velocity flow of lthe incoming gaseous material across the surface of the bed. Since the catalyst particles are not more than l5 and preferably about 2-8 millimeters in average diameter, they are incapable of withstanding high-velocity gas flow` horizontally across the surface of the bed.
Gaseous material is` introduced into the reactory 11 through a venturi-shaped nozzle 17 located on the top That is, the arrangement is such side of the vessel above its horizontal axis and substantially midway between its ends. Nozzle 17 is provided with a side branch nozzle 18 which, in turn, is provided with a branch nozzle 19. Suitable supply lin are connected to the nozzles 17, 18 and 19 so that, in predetermined and controlled sequence, air may be supplied to nozzle 17, -the hydrocarbon charge to nozzle 18, and steam and hydrogen to nozzle 19. Thusfall incoming gas is eventually received by nozzle 17 and is discharged therefrom vertically downward into the upper region of reactor vessel 11. A solids-free space 21 is provided above the surface of the bed to form a gas distributingzone wherein the downwardly-directed incoming gaseous material may spread over the surface of and downwardly into the bed through the covering layer of alumina balls 16.
Since the amount of gas required for the various cycles of operation is such that the gaseous material discharging from nozzle 17 necessarily enters-.the reactor vessel at relatively high velocity, such` as in the order of about ISO-200 feet per second, any directI imp ingement of the incoming gas stream upon the surface of granular material located near the gas inlet would, in the absence of suitable bed stabilizing or gas `defiecting means, such as wire screen covers, cause the particles of granular ma terial to be churned aboutV or blown from lthe central to the outermost surface area of the bed. To obviate such difficulty, it has been proposed that. a vertical pier be erected on the central portion of the arch, extending upwardly through the granularl material to a level between the surface thereof and the top of the vessel, and spaced from the discharge end of the inletnozzle a distance suincient to deflect the high-velocity gas stream toward the sides and ends of the vessel. It has been found, however, that while such structure may protect a small region of the bed `surrounding the pier and more or less directly in the path of the incoming gas stream, it will not sufficiently protect the portions of the bed more remote from the pier. Even though the pier deflects some of the gas stream outwardly in all directions, if lthe horizontal velocity component of the gasV stream is excessive in localized areas surrounding `the pier, thesolid particles may be shifted fromtheir desired fixed position.v For best results, it is obviously desirable to have a minimum of variance between the velocities of the gas entering the bed in the regions adjacent to the pier and the velocities of the gas entering the bed in the remote regions of the reactor vessel.
In order to interceptA the incoming gas stream and deect the same laterally throughout the distributing zone 21 in a manner which will provide gas velocities entern ing all surface portions of the bed well within the maximum allowable velocity, the deector apparatus or element of the `present invention, generallyTr indicated by the numeral 22, is provided.
The details of the rectangular gas deflector illustrated in Fig. l are more clearly shown"in Figs. 2, 3. and 4, the deflector being fabricated of structural elements designed and assembled to provide a rigid4 assembly readily installed and removed from its fixedV location, and designed to withstand the force of the incoming gas or vapor stream. The deflector structure is set on agroup. of four brickwork piers 23 extending upwardly from the bed supporting arch andy located at the corners of a rectangle smaller than the over-all size ofthe deector.
In its general configuration decctor 22 has the appearance of a U-shaped channel having a square base and shortupturned edges along the sides which are parallel to the axis of the vessel11.
Although deflector 22 may in its simplest' form comprise a single at plater member turned upwardly along two opposite sides so as to form a U-channel, the preferred, and illustrated, rectangular embodiment of the invention comprises a plurality of separately fabricated structural elements'which are assembled and joined, as
by bolts, rivets or welding, tov form a: unitary structure.
-v `Deilector 22 comprises three Lvl-channell members-24 having relatively shortsideportions-which;extend-upt wardly and then slightly vinwardly to provide additional i rigidity, as particularly shown in Fig. 4. The channel "members 24 have their side membersA joinedf-together by bolts 25.
VTwo additional channel `26of J-shapedcross` section have low sideportions which match the sideportions of channels 24. vThe low sides vof the-J-members aresecured by bolts 28' tothe outermost side portions of theassembly of connectedelriannelmembers 24. The
'high sidepuartions 27l ofl members 26 "are turned slightly outward along'theirupper iedge so as' to provide la bolting ange 29, and they are provided with vertical`-ribs P31l which extend the full heightof side portion 27 and also extend outwardly therefrom the full widthof the bolting flange 29. An elongated'angle'member 32` spans' the lJ-channel members 26 is reinforced and supportedfrom beneath by a rectangular framework of U-channel'members arranged sidewise and secured by bolts 34 to the bottom of channel members 24 and 2 6. The rectangular framework comprises a pair of U-channel members 35 which-are open at their ends` and a pair 5G-which are closed at their ends.' Members 35 extend entirely across the underside of the main deector assembly transversely to its direction of run, vand are locatedrat ysuch distance from the open ends of-the deector channel 22 that each channel member-35 may rest upon a vpair of the brickwork piers 23. Extending kbetween the channelk members 35 to complete the rectangularframe are the pair of U-channel members 36`whi'ch'are closed at their ends. The end portions of channel'members 36 also rest on adjacent piers 23 and their ends are securedY bybolts 37 to the base of channel 'members-35. The rectangular reinforcing framework thus formed is'attached to the,
bottom of the deector assembly by bolts '34. ,Eachv of channel members 35 and 36 is provided withvertical ribs 38 intermediate their ends 4to provide additional structural strength. f f
As stated, the entire deflector structure'` 22 rests upon the piers 23;`l Sidewise movement of the d'eilectorl is prevented by downwardly-projecting, short reinforced angle members 39 which are attached by b olts 41to the bottom of'channel members 35 and`36 closely adjacent to the inwardly-faced sides yof piers 23. f The membersv 39- l are 'slightly spaced from Vthe sidesvof the piers'r so that the entire deector structure may' readily be installed or removed. l
v -The rectangular deilectorr herein described is especially suitable for use in a cylindrical reactor vessel arranged horizontally and having substantially greater length than diameter. Since the gaseous material discharging downwardly into the central region of the reactor has a shorter distance of travel to reach the surface portionsof the bedalong the sidesof the vessel than to reach the surface portions at the ends thereof, the upturned side portions of the deflector cause thegaseous material passingqover such sides to be directed more nearly horizontally toward the sides of the vessel. The gaseous material is then deflected toward the surface of the .bed by. the curving; side walls ofthe reactor'vessel. VThe gaseous materialwhich is deflected in an. axial direction toward thelends'uof the vesselis not deflected downwardly to the same extent by the wall surfaces of the vessel. It;l has been determined experimentally that the rectangular channel-type dellector provides a satisfactorily narrow range of gas torgin accordance withthe invention: adapted to channel incoming gaseous material' toward the ends of ia cylindrical reactor such-asthat yillustrated in Fig, 1. The deectorv is. of generally annular shape.,y kIn this fembodimentfof thev invention a series of annulrfperfor'ate disks are arranged in a vertical tier beneath the gas inlet nozzle,
andare supported in vertically-'spaced relationshipby alrmate,side.l members positioned` at jdiametrically opposite sides of the reactor axis. l
The detailsrof the .annular-tde'ector are more clearly shown in Figs. 6 rand 7. The deector assembly comprisesfourrannular disks equidistantly spaced one above theother.V The `vtwo uppermost; disks 42 and/,43.have the lsa evoutefr4 diameter, whichis about 11A times the discharge diameter of theEgaS inlet, .andthe two lowermost disks 44 and 45 are likewise of equal 4outer diameter, vand f areV about equal to 'such-dischargediameten This stepdown arrangement with respect to the size of the central openings. and of the-outer diametersof .successive pairs of `disks causes a stepwise deflection of the gas fromvverticalto horizontal ow. ,i A pair of Vverticalarcuate supporting `members46 mainl tainthe positional relationship of'l uppermost diskA members42 and 43,l the members 46 extending slightly above the uppermost disk 42. 'Y
.A second pair of vertical arcuate support members-47 depend from the lowersurface of disk43 and support the f lov'vermostV disk members 44 and 45. Disk member 45,
velocities over and into the entire surface area of ther which'fforms the` bottom vof the deector assembly, is
imperforate and is set directly upon either a single brickwork pier or a group ofpie'rs located centrally below the gasinlet nozzle shownin Fig. l.2 v
The opening 4S of theuppermost perforate disk 42-is somewhatsmaller than the discharge diameter of the gas inlet nozzle which discharges thestream of gastobe deflected. The opening49y of `diskl43 is somewhat smaller than Iopening 48,y and opening151-indisk -44 is still smaller.y f
yIn striking the uppermost v.disk 42 a portion of the incoming g'as stream is deected in a. generally horizontal directionv and channeledto some, degree v.byl the upwardly projecting ends of side members 46 toward the ends of the cylindrical vessel. Gas lwhichilows over the top edge of members 46 toward thesides ofthe vessel is directed slightlyupwardand is then dellected downward by the curved wall of the vessel. y
- The. gas stream then passes successively through opening 49 in disk 43 and through opening 51 in disk 44. Portions of the gas stream are deected toward. the ends offthe vessel in each of the spacesbetweendisks 42-43, 43-44 and 44-45, the gas being channeled in such directions by the side support members 46. and 47 and the flat horizontal surfaces of disks 43, 44 and.45.l
The annular deector of Figs. 5 to 7, as well as the rectangular deector ofFigsl to 4, may be supported either on a series of vertical piers, as shown in Figs. l to Y4, or upon a single brickwork pier, if so desired.
In selecting the most suitable dimensions Afor the deflector members, and indetermining vthe optimum positionabrelationship of the d eector with respect to the discharge end of -the inlet nozzle and the walls of the reactorvessel, rconsideration must -be givento the velocity of the incoming gas,thevdischlarge diameter. ofrthe gas .theI discharge velocity of the incoming gas streamhave been determined, the size of the various elements ofthe y deflector assembly and its positional relationship vshould l bergen as. 1ro-.swarm .deefed ses t9- flow4 @was and then downwardly into the granular mass at velocities suiciently low in every portion of the gas distributing zone 21 so as to provide a substantial margin of safety in safeguarding against disruption of the surface bed.
In order to determine the optimum dimensions of the deflector assembly in terms of the' diameter of the gas inlet nozzle, a series of experiments were carried out on test models which duplicated the essential characteristics of the rectangular deector shown in Figs. 1 to 4 and the annularr deflector shown in Figs. 5 to 7 Inasmuch as reactor units of the type referred to herein normally operate with gas inlet velocities in the range of about 150-200 ft./sec. and at temperature and pressure conditions of about 1050-1150 F. and about 20-25 p.s.i.a., respectively, such conditions were contemplated in the design of the experimental equipment to be used in determining the relative merits of various types of gas deflector.
In order to obtain a design basis for construction of a suitable form of gas deector or bale a seriesl of preliminary tests were conducted on an experimental bed of 1/2 diameter alumina balls having a particle density of 2.43 kgm./liter and a bulk density of 1.88 kgm./1iter. The purpose was to determine the maximum gas velocities which could be tolerated at the surfaceof the bed without causing disruption of the surface layer and substantial displacement of the balls. It was found that a horizontal velocity of 106 ft./sec. directly over the surface of the bed was insuicient to move the balls and that a downward velocity of 123 ft./se'c. barely moved the balls. It was felt that for practical purposes of design and operation the maximum allowable velocity should be figured as being roughly about half of the experimental maximum, which would provide' a reasonable margin of safety.
In order to test various dctiector designs, a scale model which duplicated the proportions of the distributing zone was constructed, with provision for mounting the different deectors at suitable locations beneath the gas inlet nozzle. Velocity measuring means were installed at various locations throughout the horizontal area which would approximate the surface of the bed, although it was not necessary to actually provide a bed 'of granular material in order to make the necessary velocity determinations. Scale-size deilectors were constructed so as to be interchangeably mountable upon a centralV pier or supporting member located axially below thel gas inlet nozzle. All dimensional relationships wereV gured in terms of the discharge diameter of the gas inlet.
The model reactor employed in testingy the various types of deiiector comprised a semi-cylindrical vessel arranged horizontally with its curved side uppermost. The vessel was closed at its ends and had an inlet'nozzle centrally located on its cylindrical wall and an outlet nozzle at the bottom. A single pier was set on the bottom of the vessel -axially below the inlet nozzle. All sizes and distances were measured in terms of inlet nozzle diameters. The model reactor had a length of 8.08 and a radius of 1.86. The at bottom was considered to represent bed level. Provisions were made for a constant gas inlet velocity of 200 ft./sec., air being used in the experiments, and for measuring the gas velocities at various locations within the chamber.
Test I A at circular disk decctor having a diameter of 1.24 was set on top of the pier at a distance `of 0.93 below the inlet nozzle and a distance of 1.475 above the theoretical surface of the bed, that is, the level at which the protective layer of alumina ballsl would normally repose. It was found that this deector only partially deected the gas stream, and that the gas flowed downwardly and outwardly off the perimeter of the disk at about 218 ft./sec. After covering approximately half the distance to the'bed level the gas wasV owing at a.,
8 velocity of 143 ft./sec., and at the bed level the gas velocitywas still excessively high.
Test Il A built-up-rimf was-'then formed. along the perimeter of the 1.24 diameter deflector used in Test I. The rim extended upwardly a distance of 0.155, so that the distance from the top vof the rim to the gas inlet nozzle was 0.775. The presence of the vertical circumferential rim caused the ygas tov be deflected over the sidesl of the deflector in a generally horizontal direction. At the rim the gas velocity was 191 ft./sec., and at the sides of the reactor where the gas'was deected downwardly the velocity was v ft./sec.
TestIlI A at circular disk having a. diameter of 1.86 was then substituted for the 1.24 disks of Tests I andII, and it was found that the gas was deflected from the surface of the disk'toward", the ends of the reactor in a more nearly horizontal direction. The velocity at the perimeter of the disk was 200 ft./sec., and at the cylindrical wall surfaces of the reactor, where the gas was deflected downwardly toward bed level, the gas velocity was 114 ft./'sec.
Test 1V A at circular disk, having a diameter of 2.48 was then substituted, and placed at a distanceof'0z41 from the gas inlet nozzle. This deflector also caused'V the gas to flow horizontally from its outerl perimeter at excessively high velocity. ItwasA found that the high velocity persisted over too great a horizontal distance, so that when it was deflected from the side and end walls, of the reactor the velocity was still excessive.
Testv V A rectangular deflector with built-up sidesV was then substituted for the annular deflector. The deflector had a length of 1.86 and a width of 1.24, and the long sides were extended upwardly a distance of 0.31, thus forming a U-channel. The deilector was placed so that theA bultup side portions extended parallel to the axis of the reactor. The base of the rectangular channel thus; formed was located a distance of 0.93 from the gas inlet nozzle. Velocity readings were taken at various bed level locations and it was found that the maximum downward velocity of the gas at such level was 64 ft./sec.
Test VI The rectangular deector of Test V was then shortened to form a square having a length and a width of 1.24. With this modification, the maximum gas velocity at bed level was found to be 64 ft./sec.
Test VII The type of rectangular deflector used in Test V ywas then modified by attaching a cross member at each end of the U-channel, to brace the upper corners of the side extensions. The braces extended inwardly from the ends of the channel a distance of 0.31, and extendedV downwardly from the top edge of the built-up sides a-distance of 0.16. It was found that the braces did not eiectany ysubstantial change in the velocity pattern. The maximum velocity at bed level was again 61 ft./sec.
Test VIII A multilevel annular disk deector was then positioned beneath the gas inlet nozzle, it being necessary to lower the height of the pier which supported the deflector. The annular deilector was arranged so that its uppermost edges almost touched the curving cylindrical walls of the reactor. Counting downwardly, the first perforate disk had an outside diameter of 1.25 and an inside ldiameter of 0.86. The second perforate disk also had au outside diameter of 1.25, but the inside diameter was 0.71. The third perforate disk had an outside diameter of 1.04 and 9 an inside diameter of 0.52. The fourth disk was imperforate and had a diameter of 1.04. The disks were vertically spaced from each other a distance of 0.25. The slightly curved vertical side members which supported the disks in their spaced relationship, and extended generally parallel to the sides of the reactor vessel, had a width of 0.31. The vertical side members connecting the two uppermost disks extended a distance of 0.31 above the surface of the first disk to form square side extensions. The vertical side members supporting the two lowermost disks depended from `the underside of the second large disk a distance of 0.5v plus the thickness of two disks. The disks'had a'thickness of about 0.04. With this deector, it was found that the maximum bed level velocity of the gas was 48 ft./sec., thus establishing its superiority, 'at least with respect to gas velocity reduction, over the several deectors tested.
The bed level velocities in'each of Tests I, II, III and IV were too high for the particular size alumina balls tested and, since the test balls were of a size considered to be in the practical range for commercial use, the deilectors employed in these four tests were not recommended for such use under the conditions set forth. Each of the tests V, VI, VII and VIII showed bed level velocities of roughly about one-third to one-half of what was considered to be the maximum allowable velocity. The deiiectors employed in the latter tests were therefore considered to be satisfactory.
While the invention has been shown and described in several forms, it will be obvious to those skilled in the art that it is susceptible of various other modifications and changes within the spirit of the invention, and it is desired therefore than only such limitations shall be placed thereon as are imposed by the appended claims.
What is claimed is:
l. In a gas-solids contacting vessel adapted to containv granular material as a fixed bed having an exposed surface of substantially greater length than width,.said vessel having a circular gas inlet nozzle arrangedv to introduce gaseous material as a` downwardly directed, highvelocity stream centrally above said surface of said bed and a gas outlet arranged to discharge said gaseous material after passing downwardly through said'bed, the combination therewith of a gas deiiector comprising a hat horizontal portion and raised side portions extending along two opposite sides thereof to form a shallow U-channel parallel tothe longest horizontal axis lof said surface, the base of said channel having a minimum f horizontal dimension of at least about 11A times the It will be noted from the data obtained in these tests that the deectors which had opposite turned-up edges running generally parallel to the long sides of the cylindrical vessel showed a marked superiority over the other forms tested. The annular type detiector comprising multiple perforate disks proved to be the most efficient form of all. The single rectangular deflector plate with opposite turned-up edges, however, proved to be highly efficient and, in View of its simplicity of construction, was
considered easier and less costly to fabricate, install,
and maintain. The rectangular type deector was therefore thought to be the most suitable design in cases where the cost factors alluded to above are Vof importance.
It is to be understood that the invention is not limited to the particular'type of process and the particular type of reactor with which it has been identiiiedherein for the purposes Yof description and explanation. In its broadest aspects the invention has application to gassolids contacting vessels of more or less general design, but which are of such irregular dimensions that a bed of solids contained therein presents an exposed surface area of substantially` greater length than width, and ywhich receive incoming gaseous material as a downwardly-directed, high-velocity stream discharging above the surface of the bed and in such close proximity thereto that the particles comprising the surface layer tend to be churned about or otherwise displaced. The bed may be relatively deep, or may be shallow, since the invention is concerned only with bed surface stabilization.
With respect to the sizey and positional measurements given for the deector in terms of the discharge diameter of the gas inlet, they appear as odd decimals merely because the model reactor and deector were scaled in terms of inches and the measurementsA were then expressed in terms of gas inlet diameters.
In connection with the vannular type deector, it is not essential, though it may inv some cases be desirable, that the disks or plate membersk be of different outer diameter, that is, that the size of the disk be decreased as the central openings 'become smaller.
discharge diameter of said inlet nozzle and being spaced axially therebelow a distance of about Vs-l times said diameter, and the sides of said channel having a height of about M14/3 times said diameter and a length of at least about 1/3 of said diameter.
2. Apparatus as in claim l in which said horizontal portion of the deector is rectangular, and in which said raised side portions are coextensive with the long sides of said horizontal portion.
3. Apparatus as in claim 2 in which said horizontal portion is a square having a side dimension of about 1% times said dischargediameter and is spaced from saidV nozzle a distance of 1/3 'to' l times said diameter, and in which the height of said side portions is about 1/3 of'said diameter. Y
4. Apparatus as in claim 1 in which said horizontal Amember is a at annular disk having a central opening smaller than the discharge opening of said inlet nozzle and saidraised side portions are diametrically opposite f arcuate members having a length of not more than about 1/3 of said inlet nozzle discharge diameter; and including a plurality of additional disk members axially below the first disk and for-ming therewith a vertical series of horizontal deliector elements at an interspacing of about 1A of said nozzle discharge diameter, the lowermost of said additional disks being imperforate, and the intermediate kdisks having central openings` progressively vsmaller than the opening in said iirst disk; each of said additional disks being joined to the disk next above by verticalfside portions similar to said raised side portions. 5. Apparatus as in claim 4 wherein said disks are'four in number, the approximate size of the disk openings,
Vin descending order and in terms of inlet `nozzle discharge diameter, being respectively "Aa, 7/10 and 1/2.
6. Apparatus as in claim 5 wherein the two uppermostkdisks each have an outside diameter `about 11A' times, and the two lowermost disks each have an out- VVside diameter about equal to, the inlet nozzle discharge diameter.
`References Cited in the file of this patent UNITED STATES PATENTS