US2453593A - Apparatus for separating entrained solids from gases - Google Patents

Description

Nov. 9, 1948. D. H. PUTNEY APPARATUS FOR SEPARATING ENTRAINED SOLIDS FROM GASES` 2 Sheets-Sheet l Filed Jan. l1, 1946 INVENTOR. I @dy/a ,0a/wey ATI'ORN EY D. H. PUTNEY 2,453,593v

APPARATUS FOR- SEPARATING ENTRAINED SOLIDS FROM GASES Nev. 9, 1948.

2 Sheets-Sheet 2 Filed Jan. l1, 1946 INVENToR dz//d' pail/7W BY Patented Nov. 9, l948 It? i 2,453,593

UNITED griffes Y PATENT" ori-ICE David Putney, Kansas City, Mo., assignor to Stratford Development Corporation, `Kansas City; Mo.;` a corporation of Delaware npplicauonianuary11,1946,seria1No64o,620` 2 claims. (Criss-wy I 'This invention relates to improvements in apparatus for separating entrained solids vfrom gases and refers more particularly to a centrifulgal separator for` removing nelydivided particles of solid from gases or vapors.

The essential features of `novelty reside `not only in the method employed but also in the` apparatus. The apparatus includes "a wheel having a plurality of vertical blades designed toimpart rotative velocity to the mass of gas and entrained solids passed axially throughla `skimming cylinder which surrounds the wheel and which con-` tains slotted openings through which solid particles togetherwith some gas are discharged. An outer shell of larger diameter "surrounds the skimming cylinder forming] an annular space therebetween through which solid particles and gas expelled from the rotative mass pass in a downflowing stream to bel discharged from the Abottom of the other vessel. t

An object, therefore, of the linvention is to pro"m vide a gas centrifuge or clarifier for stripping or denuding gases or vapors of entrained solid par.. ticles. f

Anotherobject is to provide a centrifugal separator utilizing not only the `principle of centrifn ugal separation for removing the solid particles from the gaseous material `but also a skimming cylinder equipped with slotted openings 'for stripping the solid particles `from the outer periphery of the rotating mixture of gas and solids.

Another object is'to provide aV separator comprisingconcentric vessels, the inner vessel having apertures therein andf a rotating wheel for imparting rotating velocity to the gaseous mix- Fig. 2 is a View taken i l'in the direction ofthe arrows, I y I i Figi 3 is an enlargedview taken" along theline 3--3 in Fig. 2 in the direction of the arrows,

Fig. 4 isa view similar to Fig; 2 showing a modified type of spinning wheel,` and n Fig. 5 is a graph indicating the effectiveness of separation at different speeds of the spinning Wheel@` o 1 Referring tothe drawings and particularly Fig.

f1, at lil* isfindicated a cylindrical outer shell closed at the top by a plate I I bolted or otherwise fastened to flanges at the top of the outer vessel.

The bottom of the vessel is supported on a suitture passed through the inner vessel whereby, due I to the pumping action of the wheel, a downflowing stream is created in the annular space between the vessels which is eective inremoving solidparticles projected through the apertures in the inner vessel. n p p `A further `object isto providepa centrifugal `gas separator or clarifier able to handle large volumes of gas in a relatively smallspace. l

Other and further objects will appear from the following description.

` In the accompanying drawings which form a part of the instant specification andare tovbe read in conjunction `therewith and inv which like reference numerals indicate like parts inthe various views,

Fig. 1 isa sectional side elevational view of an apparatus embodying the invention with parts brokenaway, I I `1 I I able standard such as plate I2. Within the outer vessel and concentric `therewith is a cylindrical vessel or skimming cylinder of smaller diameter designated `bythe numeral I3.` The skimming cyinder is supportedl within the outer vessel from the top by an annular flange I3a, welded or other; Wise rigidly aiiixed to an annular baille lila .in the upper portion of the outer vessel. Mounted at the top of the outer vesselon closure plate II isa prime movery such as a motor diagrammatically indicated at I4. This motor is coupled to `and drives shaft l5 positioned centrally oflthe outer vessel and skimming cylinder. The shaftrotates upon suitable bearings at the top and bottom of the vessel. Provision is made `for preventing solid particleswcontained in the` gases from entering the bearings of the shaft by introducing clean gas or vapor into the machine through labyrinth seals or by other conventional method. Fixedly mounted upon the shaft within the skimming cylinder `isa spinning Wheel consisting of Varies I6 extending radially from a central hub.

Theskimming cylinder I3 has 4slotted aper-` tures I3b` in its shellI throughout the area surrounding the spinning` wheel. Below the wheel the shell of the skimming cylinder is` without openings except for the single tangentially connected inlet pipe `II. Extending over the slotted apertures" Itbin "the skimming cylinder are I louvers or baffles itc pitched downwardly to deect solids `and gases discharged through the apertures into the annular space between the 3 of the outer vessel above the baille plate Illa. The outer vessel has an inclined or truncated conical bottom |01) which directs solids accumulated in the vessel to a discharge pipe I9 controlled by valve 20.

In operation the gas or vapor containing the entrained solids enters the lower portion of the f `rapid rotation imparts rotative velocity to the The gas-solid mixture rises through gaseous mass passing along the blades of the wheel. These blades may either be flat vertical blades, as shown in Fig. 2, or may be curved, as indicated at Ilia in Fig. 4. Such lcurvature is intended to increase the outward pumping action or ability of the wheel thus assisting in the centrifugal separationof the solid fines. The wheel may be operated `,at any desired speed and it should abe of surcient length so all thegases passing through it will be brought up to the rotative speed of the wheel before leaving its upper end. The rotary motion imparted to the mixture of gas and solidr particles causes the solid nes to be' projected from the` periphery of the wheel by centrifugal force` because of the greater difference in density between the solids and gas-carrying medium. The solid particles projected from the extremities of the rotating blades impact the inner wall of the skimming cylinder and, due to the movement of the mass, slide around the wall in the direction of the rotation of the wheel. During their passage around the inner- -wall the particles enter and pass through the apertures in the skimming cylinder. The walls of the slots or` apertures |31) are open tangentially to the skimming cylinder so particlesy sliding along the wall are readily discharged through the openings.

`Theannular space between the skimming cylinder and the outer vessel is closed at the top. The rotation of the Wheel i6 and the pumping action lts rotation imparts to the mass builds up a pressure at the slotted openings in the skimming cylinder higher than the pressure at the shaft. This higher pressure is transmitted to the gases in the annular space through the slots `nd since the annular space is closed at the top the gases and separated solids discharged through the-slots ilow in a, downward direction through the annular space which is open at the bottom end. The fines discharged through the slots pass downwardly along the inside of the outer shell in a spiral path to the lower portion of the vessel which serves as a hopper or collecting chamber.

The lower end of the skimming cylinder may either be left open or it may be partiallyor wholly closed by plate l3d. In order to provide a down- Iflowing stream of gases inthe annular space for carrying the separated solids more rapidly downward it is vnecessary to permit the return of these gases to the inside of the skimming cylinder. If no closure plate is used on the lower end of the skimming cylinder the quantity of gases or vapors recycled to the wheel will be large whereas if the lower end ofthe cylinder is completely closed the amount of recycled gases Wil-l be nil. Best results are obtained if plate I3d is installed with a.

small annular opening around the shaft for passage of a relatively small flow of recycle gases. Since the separated solids descend sprally against the inner surface of the outer vessel wall only a very small quantity of the separated solids will be recycled with the recycle gases to the wheel if the recycle gases are required to return to the vicinity of the shaft before reentering the skimming cylinder.

i Since the gas-solid mixture passing up through the Wheel has at all times a certain amount of vertical velocity as well as rotative velocity imparted by the wheel, the resultant direction of discharge through the slots would normally have a vertical component. This vertical component would oppose the downward flow of the separated lines from other slots above. For this reason it is advisable to install louver type deflecting baffles at the slotted openings. These baffles are pitched downwardly and mechanically change the direction of the separated nes and carrying gas so the discharge from the slots into the annular space is at a downward angle. Consequently, any tendencies for ne solid particles to hang up or collect in the annular space are thus avoided.

The doughnut-shaped baille plate, installed above the separating wheel and sealed against the outer she-ll and skimming cylinder, provides an opening at its center around the shaft through which clean gas or vapor is discharged. By the time the uprising mixture reaches the top of the wheel substantially all solids have been eliminated throughv the skimming cylinder slots and this upper baie plate Illa is a further safeguard against any solid fines being discharged from the top of the skimming cylinder since it is eX- tremely difficult for the solids rotating at a rapid velocity to return to the hub of the wheel.

It is intended that the apparatus shown may be installed as a separating device wherever it is desired to denude gases or vapors of solid particles. It may be built integral with other apparatus where it is employed to separate solids from gases which aremixed in otherr portions of the apparatus. It is 'particularly adapted for use in the separation of finely divided catalyst from hydrocarbon vapors or combustion gases in catalytic cracking units, the separation of dust from the exit gases of cement kilns, etc.

Experiments have been conducted with the apparatus utilizing a l0" diameter separating wheel and skimming cylinder of the type shown. To test the separating efficiency, air was blown through a bed of standard aluminum hydrosili-V cate powdered catalyst such as is used in fluid type catalytic cracking units. IThe iiner particles of powdered catalyst were thus entrained` in the air stream leaving the catalyst bed and were introduced into the apparatus. The results of these tests are indicated in IFigure 5. Loadings to the wheel as ,shown were obtainedby measuring the carry-over rates from the top of the machine during periods when the wheel was the wheel idle, only 0.04 grain per cubic foot were carried over under the saine conditions when the wheel was operated at 1100 R. P. M. This represents a separating eiliciency of 99.97%. For lower velocities of gas passing through the wheel the separating efficiency is even higher. In general, the separating efliciency increases with R. P. M. of the wheel and decreases with gas velocity passing axially through the wheel. The design and the speed of the wheel can be chosen to suit any specic separating problem.

The details of design of the wheel and skimming cylinder shown in the drawings are not intended as a limitation to the particular design shown, as any structureutilizing the principle is within the scope of the invention. For example, the height of the slots is of little importance and although the slots have been shown in staggered formation around the cylinder such slotted openings may be continuous from the top to the bottom of the cylinder and of greater or lesser number. particularly in cases where used with gases or vapors'carrying a large amount of entrained fines, to make the openings of the lower slots of greater` It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features `and subcombinations. 'Ihis is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that'all matter Likewise, it is contemplated,l

herein set forth or shown in the drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. An apparatus for separating entrained solids from gaseous materials comprising ooncenn tric vessels of different diameters, the annular space therebetween closed at the top and open `at the bottom, an inlet opening into the outer vessel, an outlet opening in the upper portion of the inner vessel having communication with an outlet in the upper portion of the outer vessel, a solids discharge opening in the bottom of the outer vessel, said inner vessel having an opening in the bottom and thereby being in communica- Vtion with the outer vessel, rotative elements with in the inner vessel adapted to rotate the gaseous mass passing' through it and peripheral aperr Number tures in the shell of the inner vessel for the passage of solids and gases.

2. An apparatus as in claim 1 wherein the apertures in the shell of the inner vessel comprise longitudinal slotted openings having downwardly deflecting baies whereby the gases and solids passing through said apertures are deected downwardly in the annular space between the vessels.

DAVID H. PUTNEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Ash June 26, 1888 Flick Feb. 31, 1931 Harper Sept. 6, 1932 Saint-Jacques Mar. 9, 1937 Fagerberg Jan. 10, 1939

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