US2372514A - Multistage centrifugal separating apparatus - Google Patents

Description

P. Poo'rJEs 2,372,514

.MULTISTAGE CENTRIFUGAL SEPARATING APPARATUS I March 27, 1945.

Filed Aug. 29, 1941 2 Sheets-Sheet 1 PETER F00 71/55,

INVENTOR Array/gin March 27, 1945.

P. POOTJES MULT I S TAGE CENTRIFUGAL SEP ARA'I ING APPARATUS Filed Aug. 29, 1941 2 Sheets-Sheet 2 .Pzrze Poo 7215s, INVENTOR Patented Mar. 27, 1945 2.312.514 mourrsraor: onN'ranmGAr. snrm'rmo mam Peter Pooties, Temple City,

Precipitation Corporation,

Western TUS Cali!., assignor to Los Angeles, Callt, a corporation of California Application August 29, 1941, Serial No. 408,694

The present invention relates generally to gas cleaning apparatus of the centrifugal type commonly called "cyclonic separators wherein a stream of finely divided solid or liquid particles sus 'nded in a stream of gas is subjected to a w ling action to separate the suspended particles from the gas. This invention is more particularly directed to multi-stage separators in which the gas stream is passed through successive separators or stages to obtain a more effective cleaning of the gas.

An object of the invention is to provide a compact multi-stage centrifugal separator with vertically superposed successive separating stages.

Another object of the invention is to provide in a common shell or housing a plurality of vertically superposed centrifugal separating stages.

A further object of the invention is to provide a multi-stage separating apparatus in which successive stages are vertically superposed and are enclosed in a common housing and the housing forms a part of the conduit means for conducting gas between the successive stages.

In ordinary applications it is generally neces-- sary to subject the gas to centrifugal separating action in a relatively small diameter tubular separating device in order to obtain .efficient cleaning of the gas. This usually necessitates the employment of a relatively large number of tubes in parallel in each stage in order to handle the large gas volumes encountered in most installations. Accordingly, a particular object of the invention is to provide a compact arrangement of a plurality of centrifugal separating stages, in which one or more of the stages comprise a plurality of relatively small diameter tubes in parallel.

Because of the ease of manufacture and for other obvious reasons, the tubes in the multitube units and other gas confining parts thereof are fabricated from relatively lightweight metal, such as thin sheet-metal. In most applications this light construction is perfectly satisfactory since the gas is treated at or near atmospheric pressure and the pressure drop obtained in the separator is usually less than one pound per square inch, so that there is little or no tendency for the apparatus to rupture because of internal pressure. In some applications, however, it is desirable to treat gas at relatively high pressures, for example, pressures in excess of 50 lbs. per square inch. The conventional light-weight construction is entirely unsatisfactory for this purpose and it is commercially impracticable to construct the individual separating units of sufiicient weight to stand these pressures.

It is an important object of this invention to provide a, multi-stage separating device adapted for treating gases at high pressures in which the individual separating units are of light-weight construction in accordance with the usual practice.

Another important object of the invention is to provide a multi-stage separating device adapted to separate dust efiiciently from a gas having a very high dust loading and at high pressure.

How the above objects and advantages of my invention, as well as others not specifically mentioned above, are attained, will be more readily apparent by reference to the following description and the annexed drawings, in which:

Fig.- 1 is a vertical sectional view of a threestage centrifugal separating device according to my invention;

Fig. 2 is a horizontal section through the first stage taken substantially online 22 in Fig. 1;

Fig. 3 is a partly broken awa horizontal section through the second stage taken on line 3-3 in Fig. 1;

Fig. 4 is a partly broken away horizontal section through the-third stage taken substantially on line 4-4 in Fig. 1;

Fig. 5 is a partial vertical section of a variational form of the device illustrated in Fig. l, in which the first separating stage comprises a plurality of small diameter tubular separating units;

Fig. 6 is a partial vertical section of another variational form of the invention shown in Fig. 1 in which the second and third stages are provided with involute inlets instead of vane-type inlets as shown in Fig. 1;

Fig. 7 is a horizontal section taken substantially on line 1-1 in Fig. 6 illustrating constructional details of the inlet means; and

Fig. 8 is a sectional detail taken on line 8-8 in Fig. 7;

Referring to Figs. 1 to 4 of the drawings, my multi-stage separating apparatus is shown as comprising a plurality of centrifugal separating stages A, B and C enclosed within a housing I which in this form of my invention is showas an outer cylindrical shell comprising connected and aligned cylindricalintermediate sections 2, 3 and-4 and dome-shaped top andbottom sections 5 and 6 connected to thesections 4 and 2 respectively. Each section of the housing is shown provided with a flange co-operating with the next and the housing sections may :be suitably construction facilitates fabrication and repair 01' the apparatus since in some cases the vertical height of the-housing I may be considerable, ior

example, from 25 to 50 ft. or more. The severalhousing I and the inner walls of thehousing section 2 form part of the first stage. Referring to Figs. 1 and 2 particularly, thehousing section 2 is shown provided with a pain of tangential gas inlets I I and I2 through which the dust-laden 88s is introduced to the interior of thehousing section 2 which forms the centrifugal separating chamber of that stage, and is caused to swirl about the interior of the housing to centrifugally separate dust particles which are thrown to thehousing wall and travel downwardly into a conical hopper I3 communicating through the bottom section 6 with a dust delivery tube I4 through which the collected dust may be transported to a suitable delivery position in a manner wellknown in the art. A shield I5 in the form of an inverted truncated cone is shown secured between thehousing sections 2 and 3 and extending'downwardlyintothe housing section 2 to a level intermediate the inlet tubes II and I2 and is provided at its lower end with a cylindrical shield portion I6 terminating at a level slightly below the inlet tube I2 and concentrically located with respect to thehousing portion 2. The cylindrical shield I6 and its upper end Iia comprise the gas outlet tube and gas outlet opening, respectively, for stage A.

The apparatus further comprises a horizontal partition l1 extending across the interior of the housing I and secured therein as by fastening between thesections 3 and 4 where they Join.

The partition I'l defines the upper end of aninlet header compartment 29 for the second stage indicated at B. Within the housing I and spaced from the side walls thereof and located at' a position spaced vertically below the partition I1 is ahousing 2| which encloses and forms part of the second separator at separating stage 2B. Thehousing 2| comprises a substantially "cylindricalupper portion 22 having a substantiallyplane wall 23 closing its upper end and defining between it and the partition I! theinlet header 2! for the second separating stage. Thehousing 2| is further provided with abottom portion 24 generally in the form of an inverted truncated cone having at its lower end adust delivery pipe 25 which extends downward within shield I6 and through thesection 2 and out through the bottom section 6 within the dust delivery tube l4 of the first stage. Thehousing 2| is shown secured in position by means of a plurality of spaced radially extendingribs 26 secured at their inner ends to thehousing 2| and at their outer ends to the interior of theshell section 3.

Theconical bottom 24 and the flaring shield ii are spaced from one another to define anoutlet header compartment 21 for the ,first stage communicating with the outlet opening "it of the first stage.Header 21 communicates with a vertically extendingpassage 28 defined betweenside walls 22 and the interior of theshell portion 3, and the upper end ofpassage 26 communrcates with theinlet header 29.

- V aavas'ia connected together as by bolting. The sectional Stage B is shown as comprising a plurality of individual tubular centrifugal separatingunits 3| connected in parallel. Each centrifugal separating unit comprises acylindrical tube 32 suspended from wall orpartition 23 and open at itsupper end 23 to provide gas inlet means for the unit which communicates withthecheader space 28. The lower end of eachunit 3| preferably tapers to a material discharge opening 34 which is in open communication with the interior of thehousing 2|, the lower portion of which constitutes a materialcollecting compartment to whichdelivery pipe 25 is connected Located coaxially of eachunit 3| is gas outlet means provided by tube 66 supported from the partition l1 and communicating with the space in the housing I above partition I! through gas outlet opening 36. The lower end of eachtube 36 extends into the upper endof the corresponding tubular unit II. Thetubes 35 and II are secured to partitions I1 and 23, respectively, in a gas tight manner.

As may best be seen'from Figs. 1 and 3, there vis located on the lower end of each outlet tube 36 aring 31 having thereon a plurality ofcurved vanes 38 which extend radially from the ring, to the inner wall of theunit 32 and are inclined downwardly in one circumferential direction in a generally helical manner.Ring 31 and its attachedvanes 38 may beheld in place in any suitable manner, as by bolting, for example. These vanes impart to the incoming gas stream the necessary whirling motion to bring about the centrifugal separating action.

A secondinner housing 4| is provided within the outer housing or shell I above the partition I1, and encloses and forms part of the third separating stage C. Thehousing 4| comprises vertically extendingcylindrical side walls 42 laterally spaced from the inner walls of theshell section 4 to provide therebetween a vertically extending gas passage 43. Thehousing 4| is provided with aconical bottom portion 44 communicating at its lower end with adust delivery tube 45 which extends downwardly through partition I'I, through thehousing 2|, and thence through shield I6 and thehousing section 2 into the dust delivery tube H of stage A alongside oftube 25. The upper end of thehousing 4| is closed by a substantially horizontally extendingwall orjpartition 46 which is spaced vertically below a horizontally extendingpartition 41 extending across the inner housing I and held in position therein between thehousing sections 4 and 5. Thepartitions 46 and 41 define therebetween an inlet header space 48 for the separating stage C, the header space communicating with the upwardly extending gas passage 43. Thehousing 4| is suitably supported in the housing I by means ofradial arms 49. v

Separator or separating stage C is constructed in substantially the same manner as separating stage B and comprises a plurality oftubular separating units 50 suspended from thepartition 46 and each having at its upper end anopening 5| providing gas inlet means communicating with the header space 48, and at its lower end or material discharge opening 52 communicating with the interior of thehousing 4|, the lower portion of the housing 4I indicated at 53 comprising a material collecting compartment for stage C. Each of the separating units also comprises agas outlet tube 54 depending from thepartition 41 and provided with gas outlet opening 55 communicating with a gas outlet header space 66 asvaus denned in the housing between thepartition 41 and the top housing section I. The housing section is shown provided with a gas outlet opening 51 from which clean gas is discharged from the system. Thegas outlet tubes 54 extend down part way into theunits 50 and each have a plurality oi vanes 64a adjacent the lower end thereof for imparting a whirling motion to the gas as described in connection with thevanes 33.

Partition I'I extends completely across the interior of the housing I except tor the openings therein through whichgas outlet pipes 35 anddust delivery tube 45 extend, said partition thereiore completely shuts off communication, outside separating stage B, between thegas inlet openings 33 and thegas outlet openings 36 of that stage so that all the gas is required to pass through the separating units or stage B. Similarly,partition 41 extends completely across the interior of housing I except for the openings therein through which theoutlet tubes 54 extend. Thus partition 41 completely shuts oi! communication, outside separating stage C, between the gas inlet openings SI and thegas outlet openings 55, wherefore all the gas is required to pass through the separating units of stage C.

As previously described, gas from stage A passes upwardly from opening Iia intoheader 21 and thence through vertically extendingpassage 2. around stage Bv and within the housing I into theinlet header space 29 of stage B; the gas then divides into a plurality of parallel streams which enter theinlet openings 33 of the separatingunits 3|. The gas whirls downwardly in each unit and suspended solids are separated by centrifugal action and are discharged through the openings 34 into thecompartment 35. Gas from each unit then passes upwardly through thetube 35 and is discharged through theopening 36 into anoutlet header 58 defined within thesection 4 between the walls thereof, theconical bottom 44 of the housing M and the upper side oi the partition H. The gas streams from theopening 36 are re-united in theheader 58 and flow upwardly therein around stage C within the housing I to the vertically extending passage 43 communicating therewith and thence to the inlet header 48 of stage C.

The action described in connection with stage B is repeated in stage C, suspended solids being discharged from the openings 62 into thecollecting compartment 53 and gas 'being discharged through thetubes 54 into the outlet header .53.

It will be noted that the outlet header for each lower stage is defined between the partition means adjacent the gas outlet means of the lower stage and the lower portion of the inner housing enclosing the units of the adiacent upper stage. For example, the outlet header of stage A comprising thepassage 21 is defined between the shield I5 and theconical bottom 24 of the housing II. The outlet header of stage B is defined between partition I1 and theconical bottom 44 of thehousing 4|. In each case the gas outlet means for the lower stage passes through the partition means defining the upper end of the space containing that stage.

The separating units, housings therefor, and partitions, may be of relatively light weight thinwalled construction in accordance with conventional practice. For example, 16-gauge material is often used as it can be readily formed into the desired shape. Light-weight construction provides adequate strength with minimum labor and material costs. of course, thicker walls are sometimes provided for the separator units when it is desiredtoprovidealongerliieinthecaseoi abrasive dusts or corrosive gas constituents. When the gas to be treated is at low pressure, the housing I can also be constructed from lightweight material, its design being dictated by purely mechanical requirements.

The illustrated construction is readily adapted to the treatment of gas at high pressure, 50 lbs. per square inch for example, without any change except that of providing the outer housing wall with thick walls adapted to withstand high internal pressures. It is not necessary to increase the thickness or the walls of the parts contained within the housing I. It will be noted that the partition means and separating units are so arranged that all the compartments and spaces inside and outside of the separating units and stages are subjected to the high pressure of the gas stream. The only pressure diflerence that exists between parts within the shell or the housing is that which obtains from the normal operation of the device.

In referring to light-weight or conventional construction, reference is made to the thickness or the material used for the separating units and the co-operating inlet and outlet chambers when that thickness is determined independently oi! the gas pressures as would be the case it the exterior oi the units were maintained at atmospheric pressure and the gas stream within the apparatus were substantially at atmospheric pressure. Normally the gas pressure differentials from the walls of the unit are then only those diflerentials created by the draft necessary for passing gas through the apparatus. Under these circumstances, the thickness of the material used is independent of the gas pressure and is dictated solely by the dead loads of the apparatus and by other considerations, such as rigidity and long life. It will be appreciated that if the walls of the separating unit are made additionally thick in order to resist wear of abrasive dusts, this also may be considered conventional construction, the wall thickness is independent or any gas pressures involved. Even though the separating units may be made of a single integral wall, the situation is strictly analogous to that wherein a thin wall structure is provided with an internal liner which resists the abrasion of the suspended material. It should be appreciated that v n thou h the separating units or other part within my pressure shell are made thicker than is required by considerations of pressure and dead-weight alone, in order to resist wear, eventually the parts will be worn to a relatively thin wall, and might even wear through. Under this latter condition, units or conventional construction would not be capable of containing a gas stream maintained at a relatively high pressure, although it is possible to do so in my novel apparatus wherein the unit walls are not loaded appreciably by gas pressures.

Consequently, although from the standpoint of ability to withstand difierences of pressure, only the outer shell need be of heavy pressureresistant construction and the separating units and interior walls may be of relatively thin construction, it will be understood that it is within the scope of my invention to make the separating units or other interior walls of thick metal tor the purpose of resisting wear by abrasive dusts or corrosive gases and prolonging the useful life of the apparatus.

It should be appreciated that the tangential inlets II and I: may be replaced by a single inlet. However, in constructions oi considerable size and where the gas is maintained both at high temperature and high pressure, it is'usually advantageous from "a practical standpoint to use two smaller inlets instead of one larger one. A separate access opening for each stage is indicated at, 59 to facilitate construction and servicing of the apparatus. In order that theparallel delivery tubes 25 and 45 extending through stage A do not disturb the operation, I have provided acylindrical shield 25a coaxial with the shield l9 enclosing thetubes 25 and 49.

A modified multi-stage ,construction is illustrated in Fig. 5. This form of my invention is generally comparable to that illustrated in Figs. 1 to except that the first separator or separator stage indicated at D comprises a plurality of small diameter tubes in separator or separator stage E is quite comparable to stage B and the third separator or separator stage F is only partially shown since t may be constructed in the same manner as stage E. In general, stages D and E will comprise a larger number of tubular units than illustrated. In order to avoid the confusion occasioned by showing a larger number of tubular units, only those units in the plane of the view are shown. The stages D, E and F are located within, and spaced inwardly from, a substantially cylindrical outer housing or shell H having a conical bottom 12 defining amaterial discharge compartment 13 for stage E and having a material discharge opening 14 in the lower portion thereof adapted to be closed during operation or connected to a material delivery pipe not shown. The upper portion of thehousing 1| may be closed in the same manner as the housing I of Fig. 1 and provided with a gas outlet opening. Obviously, other stages besides stage F may be provided above stage E.

parallel. The second.

thehousing 1| through conical bottom wall 9| defining therewithin a. material collecting compartment 92' for stage E. Thematerial collecting compartment 92 is provided at its lower end with a centraldust delivery tube 93 which extends downwardly through stage D, passing through partitions I! and 19 in a gas-tight manner, and then laterally through bottom wall I! of housing ll.

Bottom wall 9| is spaced vertically from the upper partition 19 and defines therewith and in co-operation with the side-walls oi. the housing II the outlet hea'der II for stage D. Theoutlet header space 85 communicates with the vertically extending gas around stage E within the housing II.

Thehousing 81 is suitably supported within the agency of a plurality of radially extendingbrackets 94. The

upper end of the housing. .1 is closed by a horizontally extendingpartition 95 corresponding to thepartition 23 of Fig. 1, from which is suspended a plurality of tubularcentrifugal separating units 96 comparable to theunits 3| of Pig. 1. Each of the units has thematerial discharge opening 91 communicating with thematerial collecting compartment 92. Spaced vertically above thepartition 95 is anupper partition 98 in the form of an inverted cone extending across the hous- Stage D or the first stage comprises a plurality of tubular centrifugal separating'units 15-depending from a horizontal acrossrthe interior of the shell H, the units 15 i being secured to the partition I9 in a gas-tight manner. Each of the units has a gas inlet opening 11 at its upper end and a material discharge opening 18 at its lower end communicating with thematerial collecting compartment 13. The apparatus is further provided with an upper partition 19 in the form or an inverted cone which extends across the interior of the housing H andpartition 16 extending cally oi the outlet ing ll.

Inlet header orcompartment 99 for stage E, communicating with the vertically extendinggas passage 89, is defined between theupper partition 99 andthepartition 95. Gas inlet opening ill of eachunit 96 communicates with theinlet header 99. Outlet tube I92 0! each 'unit extends through the upper partition as and cdmmunicates with the space thereabove through outlet opening I93.

Conical bottom portion I94 of stage F, defining outlet compartment I Ii therefore, is located within the housing ll above thepartition 99 and is provided with a dust delivery tube I99 which .extends downwardly through the partition 9i and thence through thehousing 81concentrior delivery pipe 99 and thence laterally out 01' the housing II through the botis spaced vertically above the partition 19 to define therebetween an inlet header compartment 9! with whichthe inlet openings ll of the separating units communicate. Communicating with the inlet header 9| is gas inlet means 82 in thehousing 1|.

Each of the tubular separating units is provided with anoutlet tube 99 extending into the upper portion of its associated separating unit and provided at its lower end withvanes 84 for imparting the whirling motion to the gas. The upper ends of the outlet tubes extend through the upper partition 19 andgas outlet openings 89 withoutlet header 85 delined in the space above the partition 19.

The second stage E corresponds generally to the second stage B of Fig. 1 and comprises aninner housing 81 having generally cylindrical side-walls 98 spaced laterally or inwardly from the inner side walls of the outer housing II to provide, therebetween a verti extendinggas passage 89. Thehousing 41 is provided with a communicate through thehousing tom wall 12. An outlet header II! is defined between the vertically spacedpartitions 99 and I94 for stage E in the same manner that an outlet header is provided for stage D between the vertically spaced partitions l9 and 9|. As noted above, the construction of stage P may be similar to that of stage E, with the gas outlet means thereof connected to the above-mentioned gas outlet opening at the top or the housing, in the same manner as shown in Fig. 1.

Partition "is located adjacent the gas outlet of stage D andextends completely across ll except for the openings therein through which thegas outlet tubes 93 anddust delivery tube 93 extend. Thus said partition completely shuts on. communication, outside separating stage D, between thegas inlet openings 11 andgas outlet openings 96 of that stage, causing all the gas to flow through that stage. Similarly.partition 99 is located adjacent the gas outlet means of stage E and extends completely across thehousing 1| except for the openings through which the gas outlet tubes I92 and dust delivery pipe I99 extend. Partition 9: completely shuts oil communication, outside stage E, be-

openings ill and gas outlet or that stage, whereby all the gas is pass through that stage. operation or this form 01' my invention is caused to The e as which extends asvas'u.

same as that'described in con- 1. Gas enters the housing II throughopening 32 and flows intoinlet header 3| for stage D. The gas then passes in parallel streams through the collectingunits 13, separated material being discharged from the discharge opening 1.3 into thematerial collecting compartment 13. Gas leaves the separatingunits 13 through thegas outlet tubes 33 and is discharged through theoutlet openings 33 into theoutlet header 33. Gas then ilows upwardly within thehousing 1| and aroundstage 13 through the vertically extendinggas passage 33 into theinlet header 33 for stage E. The gas then passes in parallel streams through the separatingunits 33, separated material being discharged through theopenings 31 into thematerial collecting compartment 32. The gas then passes upwardly substantially the nection with Fig.

through the outlet tubes I32 and is discharged through the discharge openings I33 into the outlet header I31 whence it passes into the separating units of stage F from which it may be discharged from housing 1i in the same'manner as gas is discharged from the housing I of Fig. 1, or it may be passed through additional separating stages before being discharged.

The form of apparatus illustrated in Fig. is readily adapted to the treatment of gas at high pressure in that only the outer shell II and the portions of the dust delivery tubes extending therefrom need be fabricated from material heavy enough to withstand high internal pressure. Material separating units, partitions and inner housings and other parts within theouter housmg 1| may be constructed of light-weight material in accordance with conventional practice since all of these parts and the compartments defined thereby are subjected to the high pressure of the gas stream. The only pressure differential existing between the various parts is that which obtains from the normal operation of the devices. The outer housing H is shown provided with suitable access openings construction and maintenance.

Referring to Figs. 6, '7 and 8, I have illustrated I a form of my invention which is generally comparable to that illustrated in Fig. 1 except that the construction has been modified to accommodate separating units having involute type gas inlets instead of vane type for producing the whirling motion of the gas. This apparatus may comprise an outer housing III enclosing a plurality of successive, vertically spaced separating stages G. H and I. The housing III may be constructed in substantially the same manner as the housing I of Fig. 1 and may comprise vertically aligned and connected sections H2, H3 and Ill comparable to thehousing sections 2. 3 and 4 of Fig. 1. The housing III is further provided with a top section H3 and a bottom section not shown comparable to thesections 5 and 3 respectively of Fig.1. Thelower section II 2 is provided with gas'inlet means, indicated at III], and material discharge means in accordance with Fig. 1 and the side walls of ection II2 form part of stage G in the same manner that the side walls ofsection 2 of Fig. 1 form a part of stage A. The upper end of section H2 is provided with a conical shield II3 comparable to the shield I5 which extends across the housing III and defines the upper end of stage G. Gas outlet tube Ilfia of stage G depends from shield I I3, and gas outlet opening II3b of stage G communicates with the space above the shield.

I33 whereby access may be had to the interior of the housing for Stage H comprises an inner housing II1 provided with cylindrical side walls II3 spaced inwardly from the inner walls or the housing III to define a vertically extending gas passage II3 within the housing I l I around stage H. Housing H1 is also provided with a lower conical bottom wall I2I which is spaced vertically from the conical shield II3 to define therebetween an outlet header compartment I22 for the separating stage G communicating with opening N31). The space within the compartment II1 above the conical wail I2I comprises a material collecting compartment I23 for stage H. The material collecting compartment I23 is provided at its lower end with a material delivery tube I24 comparable to thedelivery tube 23 of Fig. 1, which extends downwardly through stage G to a suitable position of discharge. Housing H1 is further provided with a conical upper wall I23. Housing H1 is supported by a plurality of spaced radially extending arms II1a secured to the housing III.

Separating stage H comprises a plurality of tubular centrifugal separating units I23 each extending into the upper housing wall I23, the wall closing the spaces therebetween, and having a material discharge opening I21 communicating with the material collecting compartment I23. Each of the tubular separating units I23 is provided with gas inlet means I23 communicating with the space within the housing III above the wall I23.

The gas inlet means of each of the tubular separating units is better described in connection with Figs. 7 and 8, and referring thereto, the gas inlet means I23 is shown as comprising a vertically extending wall I23 in the form of an involute spiral having a gas inlet opening I3I extending in a vertical plane. The involute section gives the gas a circular motion before it moves downwardly into cylindrical portion I 32 of the separating unit. This vertical wall is connected at its lower edge to the cylindrical portion I 32 by transition strip I33 of tapering width. Each of the tubular separating units is further provided with a short conical gas outlet tube I34 extending downwardly for a, short distance through upper wall I 35 of the involute section substantially concentrically of the tube I32 to prevent gas from passing directly from the inlet I3I to outlet opening I33 of the outlet tube I34.

In operation the gas enters the inlet opening I 3I, is given a whirling motion in the involute section I23 and whirls downwardly in the tube I32. Suspended material is thrown to the inner wall of the tube I32 and is discharged through the opening I21 into the collecting compartment I23. The gas then whirls upwardly through the discharge tube I34 and is discharged through the opening I33.

The outer housing I I I is further provided with a conical partition I31 which extends across the interior of the housing and is spaced vertically from the inlet means I23 and located adjacent the outlet means I33 of each of the units I23 and is also spaced vertically from the upper wall I25 to define between this upper wall and the partition I31 a gas inlet header compartment I33 which communicates with the vertically extending passage H9. The gas outlet tubes 34 of each of the units I23 extend through the partition I31 and have their discharge openings I33 communicating with the space within the housing III above the partition I31.

Stage I is located vertically above stage H and is constructed in substantially the same manner.

of tubes than stage H and the tubes are or smaller diameter than the tubes shown in stage II whereby a more emcient separation of smaller particles may be obtained. Thus stage I comprises a plurality oi tubular separating units I each having involute type gas inlet means I42 adjacent its upper end, corresponding to the inlet means Ill,- communicating with inlet header compartment ill defined between an upper conical partition I extending across the housing Ill and upper conical wall III 01' an inner housing I". The housing I is provided with cylindrical side walls I41 spaced from the inner walls 01' the housing I to define therebetween a vertically extending gas passage I within the housing Ill and around stage I communicating with the inlet header compartment I. The housing I is further provided with conical bot tom wall I located above the partition i3! and spaced from the inner walls 01' the shell III to define outlet header compartment III for stage II communicating with a vertically extending gas passage I. The housing III is supported within the housing ill through the agency of a plurality of spaced radially extending brackets Illa secured to the inner wall of housing Ill.

' The space within the housing I adjacent the conical bottom I defines a material collecting compartment for stage I. A dust delivery tube Ill depends from the bottom wall I", communicates with the compartment I52 and extends downwardly through partitions I31 and I 25 of stage H and concentrically within the dust delivery tube Ill.

The lower end of each of theunits Ill extends through the wall I and has a material discharge opening lll communicating with the space within the housing I 06. Each of the units I is provided at its upper end with a gas outlet tube Ill extending through the partition I and having an outlet opening I" communicating with header space I" defined between the partition I and the upper wall III or the housthe housing through outlet opening III in the upper section Ill. 7

In general; stages 11 and I will have more tubular separating units than shown. In order to simplify the drawings it will be assumed that the units shown are those lying in the plane of Fig. 6. Partitions I31 and I are each located adjacent the outlet means of a corresponding s e and each extend completely across the interior of the housing ill, except'for the openings therein through which the associated pipe and tubes extend. Thus each partition completely shuts oil communication between the gas inlet and gas outlet openings of the corresponding stage, outside that stage. whereby all the gas is required to flow through each stage.

The operation of this form or my invention is substantially identical with that described in connection with Fig. 1, the only material difierence being the substitution of involute-type inlets for the vane-type and the modification of the partition shapes to accommodate this type of inlet. Since the same statements in regard to the adaptability oi' the device to high pressure operation can be made with this form or my invention as were made in connection with Fig. 1,

they will not be repeated.

It will be understood that while I have referred to the forms of my invention as being particularly suited to collection of suspended solid par- 2,879,514 Stage I is shown provided with a greater-number.

.ing Ill. Thecleaned gasmaybedischargedfrom ticles, all forms oi the invention may be used without material change for the collection, of suspended liquid particles.

In each 0'! the forms of my invention, it will be noted that the housing which surrounds the separating stage forms part or the wall means defining the inlet and outlet header compartments and also part oi the wall means defining the passage establishing communication between said header compartments. In this connection.

it is to be noted that said header compartments are not necessarily connected by a well-defined vertically extending gas passage such aspassage 28 of Fig. 1. Thus an inner housing suchas a housing I" (Fig. 6) need not have a cylindrical wall portion Ill, but the top and bottom walls I" and I may adjoin. Under such circumstances, the passage I no longer exists and the header compartments I and Iii are contiguous and define a passage within the housing I around stage I.

Having described various embodiments of my invention, it will be apparent that many changes may be made in the arrangement and location of parts without departing from the spirit and scope of my invention; and consequently, it is to be understood that I am not limited to the specific forms disclosed, but the foregoing description is to be considered as illustrative of rather than limitative upon the scope of the ap ended claims.

I claim: I

1. In apparatus for centriiugally separating suspended material from a stream of gas, the combination which comprises: a substantially vertically extending cylindrical housing; first partition means within the housing cooperating with the lower portion of the housing to form therein a first centrifugal separator embodying a separating chamber having acentrally located gas outlet at its upper end; inlet means in the housing'ior delivering gas tangentially into said chamber; second and third centrifugal separators located in said housing above said partition means, the third separator being located above the second separator, said second and third 9- arators each comprising a plurality of tubular centrifugal separating units, and each having gas inlet means-"and gas outlet means at its upper end, said second separator being spaced inwardly from said housing to provide a passage within the housing and around that separator for conducting gas from the gas outlet of the first separator to the gas inlet means of the second separator, said third separator being spaced inwardly from said housing to provide a passage within the housing and around that separator for conducting gas from the gas outlet means of the second separator to the gas inlet means of the third separator; a partition means corresponding to each of said second and third separater extending within the housing adjacent the gas outlet means 01' the corresponding separator and shutting on" communication, outside that separator, between the gas inlet means and gas outlet means oi that separator; and gas outlet means in the upper portion of said housing communicating with the gas outlet means of the third separaton.

2. In apparatus for centriiugally separating suspended material from a stream of gas, the combination which comprises: wall means defining a substantially vertically extending cylindrical outer housing havingtangential gas inlet 1 means intermediate its ends and gas outlet means 4. In apparatus for centrifugally separating 4 tically spaced partition means extending across the interior of the outer housing at positions intermediate the gas inlet and outlet means; an inner housing located between two adjacent ones of said partition means and having upper and lower wall means spaced respectively below and above the respective upper and lower ones of said adjacent partition means to respectively define inlet and outlet header compartments, said inner housing having side wall means spaced inwardly from the outer housing walls to provide communication between said header compartments; a centrifugal separator associated with said inner housing and having gas inlet means communicating with said inlet header compartment and gas outlet means communicating with the space above the upper one of said two adjacent partition means; and a gas passageway through the lowermost of said partition means communicating with the outlet header space above said lowermost partition means, the space below said partition means comprising a separator having the inner side walls of said outer housing as part of the side walls thereof, said tangential inlet being located in said side walls.

3. In apparatus for centrifugally separating suspended material from a stream of gas, the combination with. a vertically extending cylindrical outer shell having a gas inlet opening and a gas outlet opening above the inlet opening, of a plurality of vertically superposed centrifugal separators entirely within the shell. each of said separators comprising a plurality of tubular centrifugal separating units each having a vertically extending central gas outlet tube provided with an outlet opening at its upper end, each of said units having an inlet opening located below its associated outlet opening, and each of said units having a material discharge opening located below its associated inlet opening; a separate material collecting hopper for eachof said separators, each of said hoppers being spaced from the side wall of the shell to provide a passage for the gas stream upwardly therebetween to the inlet openings of the units of the separator with which the hopper is associated, each hopper being provided with an upper wall sealing the spaces be tween the units of the separator with which it is associated; and a separate partition extending across the interior of the shell above the inlet openings of each separator and sealing with the outlet tubes of the separator with which it is associated and defining with the walls of the shell an outlet header compartment with which the outlet openings of the associated outlet tubes communicate.

juxtaposed compartments; a

centrifugal separator in two adjacent ones of said suspended material from a stream of gas, the combination with a vertically extending cylindrical shell having a gas inlet opening and a gas outlet opening above the inlet opening, of a plurality of vertically spaced partitions dividing the interior of the shell into a plurality of vertically separate multi-tube compartments, each separator having gas outlet means communicating with the space in the shell above the partition defining the upper end of the compartment in which that separator is located, each separator. having gas inlet means located below the partition defining the upper end of the compartment in which the stage is located, and each separator having material discharge means located below its associated gas inlet means; and a separate material collecting hopper located in each of said two adjacent compartments, communicating with the material discharge means of the corresponding separator, said hoppers being spaced from the side walls of the shell and from said partitions to provide communication from the space below each of said hoppers to the gas inlet means of the corresponding separator.

5. In apparatus for centrifugally separating suspended material from a stream of gas, the combination which comprises: a vertically extending substantially cylindrical outer housing;

a first partition extending across the housing and defining part of a first centrifugal material separating means in the lower end of the housing, the lower 'part of the housing acting as a mate? rial receiving hopper for said separating means, said partition having an opening therethrough for the upward flow of gas discharged from said separating means; a second centrifugal material separating means located above the first separating means and having a gas outlet opening, a gas inlet opening below the outlet opening and a material discharge opening below the inlet opening: a second partition separating the gas inlet from the gas outlet opening corresponding to the second material separating means; and a material collecting hopper communicating with said material discharge opening and located in the shell above the first partition and below the gas inlet opening and spaced inwardly from the side walls of the shell to define a passage therewith for the upward flow of gas from said first-mentioned opening to said gas inlet opening.

PETER POOTJES.

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