US2674499A - Elevation of granular solids - Google Patents

Description

April 6, 1954 c. H. THAYER 2,674,499

ELEVATION OF- GRANULAR SOLIDS Filed April 16 1951 Fly! 2 Sheets-Sheet l INVENTOR. CLARENCE H. THAYER ATTORNEYS April 6, 31954 c, H. THAYER 2,574,499

ELEVATION OF GRANULAR SOLIDS Filed April 16, 1951 2 Sheets-Sheet 2 4? Fig.4 46 46 i l I 43 4| E I 42 1:; 5 :T. 4;" T 5 I 44 I 44 INVENTOR.

CLARENCE H. THAYER ATTORNEYS Patented Apr. 6, 1954 UNITED STATES PATENT OFFICE 2,674,499 ELEVATION 0F GRANULAR SOLIDS Clarence H. Thayer, Wallingford, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application April 16, 1951, Serial No. 221,285 6 Claims. (Cl. 30259) particularly to the separation of solids from gas after such elevation.

according to the present invention granular of lifting gas. After discharge from the confined zone, gas and solids pass through the expansion zone as a rising stream. The solids in the rising stream are concentrated near the center thereof, rising stream expands toward the periphery thereof and outwardly therefrom.

removed from the periphery, the remainder of the lifting gas expands laterally toward the pe- The method of the present invention, as described above, advantageously provides for a more rapid lateral expansion of the rising stream of gas and solids than can be obtained according to prior art methods. This lateral expansion is advantageous in that it results in a more rapid deceleration of the solids in the rising stream so that these solids reverse direction and fall out above, for use in the elevation of granular solids which are subject to substantial attrition upon striking rigid solid surfaces.

conversion and inert refractory contact material such as is frequently used in noncatalytic conversion of hydrocarbon materials. types of granular solids can be elevated according to the present invention.

The method of the present invention is particularly advantageously used with mixtures of coarse granular solids, which mixtures contain for example a major proportion of solids which result in a relatively high attrition of the solids unless measures are taken, such as the method of the present invention, to reduce the attrition.

The lifting gas which is used according to the method of the present invention can be any suitable lifting gas. It can be either a material which is unreactive with the solids which hydrocarbon conversion temperatures, of granular contact material capable of promoting hydrocarbon conversion.

According to the present invention granular solids are elevated through an elongated confined zone before being discharged into the expansion zone as described above. The invention is particularly advantageous when used in lifting operations wherein the length of the elongated zone is at least 50 times the major dimension of the cross section of the confined zone. When solids are lifted through such elongated confined zones a relatively high velocity of lifting gas must be employed, with resulting high attrition unless measures, such as the method of the present invention, are used to reduce attrition. In many industrial processes it is necessary to elevate solids at relatively high rates through distances of 100 feet or more and the method of the present invention can be advantageously used in many such applications.

The invention will be further described with reference to the attached drawings. Figure l is a schematic diagram of a system of apparatus employing a gas lift from a low level in the system to a high level therein. Figure '1 does not show any details of the apparatus employed according to the present invention and merely illustrates the type of system to which the invention is advantageously applied. Figure 2 is a sectional elevational view showing details according to the present invention, of a disengaging vessel providing an expansion zone into which solids and gas are discharged from the top of a confined lift conduit. Figure 3 is a sectional plan view of the disengager shown in Figure 2. Figure 4 is a sectional elevational view of another type of disengager to which the invention may be applied. Figure 5 is a sectional plan view of the disengager shown in Figure 4.

Referring now to Figure 1, there are shown therein reaction vessels I0 and H, a gas lift engaging vessel l2, a gas lift disengaging vessel l3, and a lift conduit I4 communicating at its lower end with engaging vessel I2 and communicating at its upper end with disengaging vessel |3.

In operation granular solids gravitate downwardly from disengaging vessel |3 through line into reaction vessel H) which may be, for example, a hydrocarbon conversion reactor. After gravitating downwardly through vessel It), the solids pass therefrom into vessel H which may be, for example, a regenerator as used. in a hydrocarbon conversion process. The solids gravitate through vessel H and therefrom through line I! into engaging vessel l2. Lifting gas is introduced into engaging vessel l2 through line if! and rises through lift conduit I4 carrying suspended solids with it. Lifting gas and granular solids are discharged from the top of the lift conduit I4 into disengaging vessel I3 and pass upwardly therein as a rising stream of gas and solids.

By virtue of the fact that disengaging vessel 53 provides an expansion space, the lifting gas expands and decelerates in disengaging vessel f3. The solids also decelerate and fall backward from the rising stream into the bottom of the disengaging vessel l3 and are removed downwardly through line IS. The lifting gas is removed separately from the solids through line l9.

Referring now to Figures 2 and 3, there is shown in these drawings disengaging vessel I3 above and communicating with the upper end of lift conduit H. The disengaging vessel shown in Figures 2 and 3 has a shape which is particularly well adapted for use in apparatus providing a plurality of disengaging chambers within a single disengaging vessel. Such apparatus is useful in certain industrial applications, as discussed in copending application, Serial No.

203,323 of Clarence H. Thayer, filed December 29, 1950.

Disengager vessel l3 provides therein a space directly above the upper end of lift conduit H. Lift conduit l4 being shown as cylindrical in Figure 2, the space above the top of the lift conduit I4 is a cylindrical space extending upwardly to transverse baflle 30. Vessel |3 also provides an expansion space laterally disposed with reference to the space directly above the top of the lift conduit. Within this expansion space an inclined bafile 3| is supported by rods 32 and 33. This baffle has the shape of a portion of an inverted frustoconical section. The side of the frustoconical section is inclined downwardly toward the space directly above the top of the lift conduit. The baflle 3| extends a little less than half way round the periphery of the space directly above the top of the lift conduit and at no point does it extend into that space. Also shown in Figure 2 are an outlet 34 for lifting gas at the top of vessel l3 and an outlet 35 for granular solids at the bottom of vessel |3.

In operation granular solids and lifting gas are discharged from the upper end of lift conduit l4 and pass through the space directly above the top of the lift conduit as a rising stream of gas and solids. The solids in the rising stream are concentrated at the center thereof, and do not substantially impinge on the baffle 3|. The lifting gas on the other hand, as it rises from the top of the lift conduit l4 expands laterally toward the baffle 3| and a portion of that lifting gas is removed from the periphery since it impinges on the under side of baffle 3| and is deflected upwardly and laterally away from the rising stream. The remainder of the lifting gas as it passes above the lower edge of the baffle 3| expands toward the periphery of the rising stream to take the place of the lifting gas which has been removed. As the rising stream passes upwardly in vessel |3 it decelerates and the solids fall backwardly therefrom toward sidewall 36 of the vessel l3. The solids fall into the bottom of vessel I3 and are removed through line 35. The lifting gas passes around and above the baffle 30 and is removed substantially separately from the main bulk of the granular solids through outlet 34. The portion of lifting gas which is removed underneath bafiie 3| passes around the upper edge of that baffle and upwardly through the disengaging vessel i3 and is commingled in the upper portion of vessel |3 with the remainder of the lifting gas and passes therewith through outlet 34. By this time, however, the lifting effect of the removed portion of the lifting gas has been dissipated and the original removal of this lifting gas has caused the solids to rise less far in the vessel |3 than they would if the gas were not removed under baffle 3|.

Figures 4 and 5 illustrate a form of disengaging vessel |3 which differs from the disengaging vessel shown in Figures 2 and 3 in that lift conduit I4 in Figures a and 5 is positioned centrally with regard to the disengaging vessel rather than at the side thereof as in Figures 2 and 3, and also in that the bafiles used as shown in Figures 4 and 5 to deflect a portion of the lifting gas in the rising stream extend around the entire periphery of the space directly above the lift conduit. In Figures 4 and 5 there are shown also a plurality of baffles 40, the baffles being vertically spaced apart. Each baffle has an inner portion in the shapeof an inverted frustoconical section 4| and an outer portion in the shape of an upright frustoconical section 42. The two frustoconical sections in each bafile 40 are connected at their tops by a smoothly curved surface 43. The base diameter of the inverted frustoconioal section in each baflle above the lowermost baffle is greater than the base diameter of the inverted frustoconical section of the adjacent baifle therebeneath and the base diameter of the inverted frustoconical section of each bafile above the lowermost baffle is less than the diameter of the top of the inverted frustoconical section of the adjacent baiiie therebeneath.

Also shown in Figures 4 and are supports 4d providing the desired spacing of the baffles 40 from each other and from the top of lift conduit I4. Transverse bafile 45 is supported from the top of vessel l3 by means of support rods 45. Also shown in Figure 4 are the gas outlet 41 at the top of the vessel I and a solids outlet 48 from the bottom of vessel l3.

The operation of the apparatus shown in Figures 4 and 5 is similar to the operation of the apparatus shown in Figures 2 and 3, one difference being that with the apparatus of Figures 4 and 5, lifting gas is removed from around the entire periphery of the rising stream of gas and solids as that stream passes through the central apertures of the bafiles 4!}. Another difiference is that with the apparatus of Figures 4 and 5, the lifting gas which is removed and passes underneath each baffle 40 is reversed in its direction of vertical movement after it is passed upwardly and laterally beneath the inner frustoconical section, and after such reversal is passed downwardly and laterally underneath the outer frustoconical section. This type of operation is preferred in that it minimizes the tendency of the lifting gas to rejoin the rising stream passing above the baffles 40.

In Figure 4, the smoothly curved connecting portions 43 of the baffles 40 have the general shape of an upper portion of a torus coaxial with the lift conduit, that upper portion being the portion lying above the zontal plane with the torus. It is to be understood that, according to the invention, the connecting portions 43 can be used in the absence of the upright frustoconical sections 42, in which case the connecting portions upper portion of each baffle, an outwardly and downwardly turned lip, which in turn provides a reversal of direction of vertical movement for the gas removed beneath each battle.

The apparatus and operation as described above in connection with Figures 4 and 5 represent the application of the present invention to a type of apparatus wherein the disengaging vessel provides an expansion space which completely surrounds the space directly above the top of the lift conduit. The apparatus and operation as described in connection with Figures 2 and 3, on the other hand, represent the application of the invention to a type of apparatus wherein only a portion of the space directly above the top of the lift conduit communicates with an expansion space providing a significant degree of lateral expansion. Referring to Figure 3, lift conduit is being adjacent sidewall 3! of disengager I 3, the only substantial lateral expansion provided for is toward the wall 35 of vessel 13. According to the present invention, the inclined baflle which is used to remove a portion of the lifting gas preferably extends completely around that portion of the space directly above intersection of a hori- 43 provide, for the the top of the lift conduit which communicates with the expansion space providing space for substantial lateral expansion of lifting gas. Baffle 3| shown in Figure 3 has this preferred construction.

Ba-ffies 4B which are used according to the present invention and which are of inverted frusto- 30 They also preferably have outer upright frustoconical portions which are inclined to the horizontal within the approximate range of 30 to 60. Baffle 3| has a like inclination to the horizontal and may be provided (although it is not so shown) with an extension like those pro vided for baiiles 49, having a like degree of inclination.

The horizontal distance of the outermost portion of each bafiie from the longitudinal axis of the lift conduit is preferably within the approxitral solids stream gradually Widens and expands laterally beyond the space directly above the top of the lift conduit. The rate of expansion varies with the operating conditions. The baifle plate used according to the present invention does not extend into the space occupied by the central solids stream. For any set of operating conditions, a person skilled in the art can, in the light of the present specification, determine the position of the baffle plate which provides substantial interruption of vertical upward movement of lifting gas without substantial interruption of upward movement of solids.

The vertical level at which a bafile according to the present invention is positioned can vary. The level is preferably one at which the central solids portion of the rising stream has expanded laterally relatively little. If the baffle is positioned at a level where the central solids stream has expanded laterally to a relatively great degree, there is a greater tendency for stray solid particles to strike the baffie surface, with resulting greater attrition of particles and erosion of the bafiie. Generally, it is preferred for the above reason that the vertical distance from the bottom of the baffle to the top of the lift conduit should not be substantially greater than ten times the major dimension of the cross section of the top of the lift conduit.

More preferably, the bottom of the lowermost baffle plate, or of the single baffle plate if only one baffle plate is used, is vertically spaced apart from the upper end of the lift conduit 9. vertical distance within the approximate range 0.1 to 1.0 times the major dimension of the top of the lift conduit.

The baflie e! or (453 according to the present invention is vertically spaced apart from the rigid surface providing an upper boundary of the space directly above the top of the lift conduit, such surface for example as the baffle plate as in Figure 2, a distance great enough to allow, above the baiile, a sufiicient space for reversal of direction of movement of solids. A person skilled in the art can, in the light of the present specifica- 7 tion, determine what this distance should be for a given set of operating conditions.

A baffle having given dimensions can be moved upwardly or downwardly relative to the top of the lift conduit to compensate for changes in operating conditions. For example, if the velocity of the gas-solids rising stream is decreased, with resulting more rapid lateral expansion of the central solids stream, the baffle can be moved downwardly to prevent the solids for impinging thereon. Means for vertical adjustment of the baffle not being herein claimed and being within the skill of the designer, is not shown.

The following example illustrates the inven- A gas lifting operation was carried out in apparatus including a disengaging vessel substantially as shown in Figures 4 and 5. An eight-inch diameter cylindrical lift conduit was used, the top of the conduit being positioned about 17.5 feet beneath a transverse baffle such as the baffie 45 shown in Figure 4. The lowest baffle plate had base diameter of about 8.7 inches and the bottom of the lowest baffle plate was spaced apart from the top of the lift conduit, a vertical distance of about 2.5 inches. The intermediate bafiie plate had base diameter of about 9.7 inches and had its bottom spaced about 4 inches vertical distance from the bottom of the lowest baffle plate. The highest baffle plate had base diameter of about 10.7 inches and had its bottom spaced about i inches vertical distance from the bottom of the intermediate baffle plate. Each baffle plate was slightly less than 4 inches in vertical height, from the bottom thereof to the highest point of the smoothly curved connecting portion thereof. The angles of inclination of both frustoconical portions of each baffie were about 45 with the horizontal. The overall Width of the lowest baffle was about 20 inches; of the intermediate baffle, about 21 inches; and of the highest baille, about 22 inches. All three baffles were concentric with the lift conduit.

The operation of the disengager described above with the three inclined baille plates in place was compared with that of the same disengager with all three baffle plates removed. In each case, the disengager was used as part of a gas lift system including an engager vessel, wherein solids were suspended in lifting gas, and a lift conduit extending upwardly from the engager to the disengager. The solids elevated were cracking cata lyst pellets, a major proportion of which were large enough to be retained on a 20 mesh U. S. sieve series screen, and substantially all of which were small enough to pass a 3 mesh U. S. sieve series screen. Compressed air was used as the lifting gas. In each case, the maximum height of rise of solids above the top of the lift conduit was measured. It was found that at the same lifting gas and solids rates, the height of rise of solids above the top of the lift conduit was about 1.5-2.0 feet less when the baffle plates were in place than when they were not. For example, when the lifting gas and solids rates were such as to provide a solids velocity at the top of the lift conduit of about 31 feet per second, the following were the heights of rise:

Feet Without baille plates 11.5 With baflle plates in place 9.5

The solids velocity given above was calculated according to the following formula:

Where us is solids velocity in feet per second, rig is lifting gas velocity calculated by dividing the measured lifting gas rate in cubic feet per second by the average cross-sectional area of the lift conduit in square feet, D5 is average particle diameter of the lifted solids in feet, and ds/dg is the ratio of densities of the lifted solids and of the lifting gas.

When a plurality of baffle plates are employed according to the present invention, it is preferred that the vertical distance between the bottom of each of the upper baffle plates and the bottom of the adjacent bafile plate therebeneath should be within the approximate range 0.1-1.0 times the major dimension of the cross section of the upper end of the lift conduit.

The invention claimed is:

1. In apparatus for elevating granular solids by means of a, lifting gas through a lift conduit and into a disengaging vessel providing therein a vertically elongated space directly above the top of the lift conduit and providing, surrounding and in communication with said space, a vertically elongated expansion space for expansion of lifting gas, the improvement which comprises: a plurality of vertically spaced apart, concentric bafiie plates each within said expansion space and positioned adjacent and surrounding said space directly above the top of the lift conduit, each bar"- iie plate having an inner inverted frusteconical portion inclined at an angle with the horizontal within the approximate range 30 to 60 and an outer upright frustoconical portion joined at its top to the top of said inverted frustoconical portion by a smoothly curved surface, the base diameter of the inverted frustoconical portion of each baffle plate above the lowermost baffle plate being greater than the base diameter of, and less than the top diameter of, the inverted frustcconical portion of the adjacent baffle plate beneath, the bottom of each baflle plate being vertically spaced apart, from the bottom of the adjacent baffle plate beneath, a distance within the approximate range 0.1-1.0 times the major dimension of the cross section of the upper end of said lift conduit, and the bottom of the lowermost baffie plate being vertically spaced apart from the upper end of said lift conduit a distance within the approximate range 0.1-1.0 times said major dimension, and the base diameter of said upright frustoconical portion being within the approximate range 2-5 times said major dimension.

2. In apparatus for elevating granular solids by means of a lifting gas and for separating granular solids from lifting gas after such elevating, which apparatus comprises a lift conduit and disengaging chamber within which the upper discharge end of said lift conduit is positioned, disengaging chamber providing above said upper discharge end of said lift conduit a space for upward travel of granular solids and lifting gas and providing, laterally positioned with regard to said space for upward travel, a space for downward travel of granular solids, said disengaging chamber having outlets for granular solids and lif ng gas, the improvement which comprises: a baffle plate within said disengaging chamber and positioned between said space for upward travel and said space for downward travel, said bafiie plate being downwardly inclined toward said space for upward travel, the lower end of said baffle plate being spaced above said upper discharge end of said. lift conduit and adapted to interrupt the vertical upward movement of lifting gas at the periphery of the stream of lifting gas rising through said space for upward travel.

3. Apparatus according to claim 2 wherein said baflie plate extends partially a substantial distance around the periphery of said space for upward travel.

4. Apparatus according to claim 2 wherein said baffle plate extends substantially entirely around the periphery of said space for upward travel.

5. Apparatus according to claim 2 wherein said bafiie plate has an inverted frustoconical portion extending substantially entirely around the pe- 'riphery of said space for upward travel, the lower end of said portion being adapted to interrupt the vertical upward movement of lifting gas at the periphery of said stream, and has an upright frustoconical portion whose top is connected by a smoothly curved portion to the top of said inverted frusto-conical portion.

6. Apparatus for elevating granular solids by means of a lifting gas and for separating granular solids from lifting gas after such elevating which References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Jensen June 24, 1924.- Ennis Aug. 24, 1926 Burt Feb. 21, 1933 Angell Nov. 15, 1949

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