CA1123403A - Centrifuge apparatus - Google Patents
Centrifuge apparatusInfo
- Publication number
- CA1123403A CA1123403A CA375,998A CA375998A CA1123403A CA 1123403 A CA1123403 A CA 1123403A CA 375998 A CA375998 A CA 375998A CA 1123403 A CA1123403 A CA 1123403A
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- Canada
- Prior art keywords
- passageway
- slurry
- bowl
- axis
- rotational velocity
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
An accelerator for a centrifuge having an upstanding shaft and upper and lower portions of a bowl member secured to the shaft for rotation therewith is disclosed. The bowl member forms a chamber for centrifugally separating a slurry into a product component and an effluent component and has means for discharging the product component therefrom. The shaft has a passageway therein for receiving the slurry and for dis-charging it to an axially lower portion of the passageway, which lower portion has a circumferentially and radially outermost extent located radially outwardly of an uppermost end of a passageway in the lower bowl portion. The shaft passageway is provided with vanes to control the rotational velocity of the slurry passing through the passageway.
An accelerator for a centrifuge having an upstanding shaft and upper and lower portions of a bowl member secured to the shaft for rotation therewith is disclosed. The bowl member forms a chamber for centrifugally separating a slurry into a product component and an effluent component and has means for discharging the product component therefrom. The shaft has a passageway therein for receiving the slurry and for dis-charging it to an axially lower portion of the passageway, which lower portion has a circumferentially and radially outermost extent located radially outwardly of an uppermost end of a passageway in the lower bowl portion. The shaft passageway is provided with vanes to control the rotational velocity of the slurry passing through the passageway.
Description
3'~
This is a divlsion of Canadian Application Serial No.
296,350 filed February 6, 1978.
Centrifugal separators or cen-trifuges Eor numerous applications such as for separating ~luid mixtures into relatively higher density and lower density fractions are well known in the art. The hydraulic transporting of mill tailings to pro~ide a mine backfill material is one well known example of such prior applications. ~egardless of the applica~ion, prior centrifuges have required that ~, the incoming material or slurries be accelerated and ~ ':
distributed pxior to the material being SU~; ected to ,, centxifugal separation. In view of the numerous structures o~ prior centrifuges it is impractical to comment upon '' all known structures for distributing and accelerating slurries; ho~ever, many o~ such structures ha~e various ~' disadvàntages as compared to the structure oE this inven-tion. Thus, many prior centrifuges have distributor~
accelerators ~ich have high fabrication cost, high pressure discharge, high operational energy requirements and/or create undesirable turbulence in the separating bowl.
In particular, the distributor-accelerator of many prior ' I ' I
centrifuges has been dependent upon the back pressure ~ -- generated within the separating bowl to provide the necessary back pressure on the incoming slurry which dependency creates an undesired turbulence and lowers the separating efficiency of the centrifuge.
Similarly ~arious prior mechanisms for control-ling the discharge of material from the separating bowl of a centrifuge have,one or more of various above stated , disadvantages. Further, some prior discharge control mechanisms have utilized differences in hydrostatic pressures within the centrifuge which make such mechanisms
This is a divlsion of Canadian Application Serial No.
296,350 filed February 6, 1978.
Centrifugal separators or cen-trifuges Eor numerous applications such as for separating ~luid mixtures into relatively higher density and lower density fractions are well known in the art. The hydraulic transporting of mill tailings to pro~ide a mine backfill material is one well known example of such prior applications. ~egardless of the applica~ion, prior centrifuges have required that ~, the incoming material or slurries be accelerated and ~ ':
distributed pxior to the material being SU~; ected to ,, centxifugal separation. In view of the numerous structures o~ prior centrifuges it is impractical to comment upon '' all known structures for distributing and accelerating slurries; ho~ever, many o~ such structures ha~e various ~' disadvàntages as compared to the structure oE this inven-tion. Thus, many prior centrifuges have distributor~
accelerators ~ich have high fabrication cost, high pressure discharge, high operational energy requirements and/or create undesirable turbulence in the separating bowl.
In particular, the distributor-accelerator of many prior ' I ' I
centrifuges has been dependent upon the back pressure ~ -- generated within the separating bowl to provide the necessary back pressure on the incoming slurry which dependency creates an undesired turbulence and lowers the separating efficiency of the centrifuge.
Similarly ~arious prior mechanisms for control-ling the discharge of material from the separating bowl of a centrifuge have,one or more of various above stated , disadvantages. Further, some prior discharge control mechanisms have utilized differences in hydrostatic pressures within the centrifuge which make such mechanisms
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3~3 undesirably dependent upon the rotational velocity of the centrifuge and the densities of the ma-terials having the utilized hydrostatic pressures. Other control mechanisms have utilized flexible membranes which require proper installation and are subject to rupture. The various prior control mechanisms have been subject to various disadvantages such as tilting, abrasion, complex components and the like such that a complete enumeration of all such disadvantages is impractical.
The aforementioned problems with respect to controlling the discharge of material from the separating bowl of a centrifuge are overcome by the invention of the parent application which broadly defines a centrifuge comprising: an elongated shaft member rotatable about the longitudinal central axis thereof, a bowl member having formed portions rigidly secured to axially spaced portions of the shaft member, respectively, the formed portions extending radially outwardly of and circumferentially encompassing the central axis to form a chamber therebetween, one of the formed portions having with respect to the axis a separate radially outermost annular segment which is axially movable from a closed position in engagement with a circum-ferentially extending outer peripheral section of the other of the formed portions to an open position axially spaced from the outer peripheral section to form a material discharge opening ~ i~
solely between the annular segment and the outer peripheral section, at least one of the members having means for introducing a slurry into the bowl member, the bowl member having means for discharging an effluent constituent of the slurry, and actuator means cooperably connected to the one of the formed portions and the annular segment for selectively axially positioning the annular segment.
On the other hand the problems relating to prior art distributor-accelerators as enumerated above are overcome by the present invention which broadly provides a centrifuge comprising:
sd ~
~ 3 an elongated upstanding shaft rotatable about -the longitudinal central axis thereof; a bowl member having upper and lower formed portions secured to axially spaced portions of the shaft, respectively, for conjoint rotation therewith; the bowl member forming a chamber for centrifugally separating a slurry into a product constituent in a radially, with respect to the axis, outer portion of the bowl member and an efEluent constituent at a portion of the bowl member radially inward of the product con-stituent; the bowl member having means for discharging such constituents therefrom; the lower formed portion having a lower-most section with a formed through passageway therein having, relative to the axis, an axial extent with the axially uppermost ena thereof being in open communication with the interior of the bowl member, the shaft having a passageway therein for receiving a slurry and for discharging the slurry to an axially lower portion of the passageway, the lower portion of the passageway having, relative to the axis, a circumferentially and radially outermost extent located radially outward of the uppermost end;
and, the passageway having means to control the rotational velocity of a slurry flowing through the passageway. . : ~.
Furthermore the present invention can be seen as also providing a method of controlling the axial and rotational velocity of a slurry continuously supplied to a rotary bowl centrifuge rotatable abou-t an axis wherein the slurry is supplied through an elongated passageway in the bowl and subsequently separated in the bowl into a product constituent located within and discharged from a radial outer portion of the bowl and an effluent constituent located radially inwardly of the product constituent and discharged therefrom comprising, initially simul-taneously rotationally accelerating and increasing the hydrostatic pressure of an incoming slurry with such a passageway, immediately after such initial accelerating further increasing the rotational velocity of such a slurry with such passageway by having such sd/~ _4_ slurry flow towards -the axis, and immediately after such further rotational acceleration discharging such a slurry from such passageway into the interior of such a rotary bowl at a rotational velocity substantially equal to rotational velocity of such a product constituent.
These and other features of this invention will be bet-ter understood upon consideration of the following detailed descrip-tion of presently preferred embodiments thereof taken in con-junction with the following drawings r wherein:
Fig. 1 is a cross-sectional view with portions there-of in side elevation of a centrifuge apparatus constructed in accordance with the principles of this invention;
Fig. 2 is an enlarged cross-sectional view with sd/~ -4A-.,, : :.- .
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.~' . . ', portions thereof in side elevation of a material discharge control mechanism as shown in Fig. l;
Fig. 3 is an enlarged cross sectional view of the distributor-accelerator structure as shown in Fig. l;
Fig. 4 is a view similar to Fig. 3 o:f another embodiment of a distributor-accelerator constructed in accordance with the principles of this invention, and Fig. 5 is an enlarged view in the open position of the structure forming the discharge opening of the apparatus as shown in Fig. 1. .
Centrifuges of the rotary bowl type are well kno~n in the art. The rotary bowl centri:Euge shown in Fig. 1 comprises a stationary formed housing 10 having vertically spaced and aligned bearings 12 for supporting an elongated sha~t 14 for rotation about its vertical rotation axis X-X. In the description herein the term radial and circumferential is with reference to the rotation axis ~-X, the term axial is with reference to the rotation axis X--X, or any axis parallel thereto, and the terms upper and lower and the like are used for convenience in this descriptio~ 1 with respect to the showing o~ the figures herein. Sha~t ¦ ;
14 is suitably rotationally driven by means of a controll-able motor (not shown) having drive belts 16 cooperable with a pulley 18 rigidly secured to the shaft 14 upwardly adjacent the housing 10. Shaft 14 is provided with a central vertically extending passageway 20 therein with the upper end being open and cooperable with a feed pipe assembly 22 to supply the material, i.e. the slurry, to be separated in the centrifuge. A separation chamber or ~0 bowl 2L~, comprising formed upper and lower members, is suitably rigidly secured to shaft 14 to rotate therewith within housing 10. The lowermost portion of the bowl 24 ha~s a distributor-accelerator member 26 which member 26 l~as an interior passageway in open communication with ports 28 extending laterally and downwardly from the inner end of passageway 20.
Bowl 24 has an uppermost central annular chamber 30 encompass-ing the upper portion of the shaft 14 with circumferentially spaced discharge ports 32 extending upwardly and outwardly of the chamber 30 and in open fluid communication therewith.
~laterial is discharged from the bowl 24 through ports 32 with the flow thereof being suitably directed within housing 10 by suitable means.
- In operation the mixture to be subjected to centrifugal - action of the centrifuge is introduced through the feed pipe `
- assembly 22 and thereafter flows through passageway 20, ports 28, member 26 into bowl 24 in which the mixture is separated ~ith the low density fraction thereof being discharged through the ports 32 and with the high density fraction thereof being discharged through the discharge opening 34 (Fig. 5). For the purposes of this invention the construction of the feed pipe assembly 22, drive pulley 18, bearings 12, shaft 14, discharge ports 32 and housing 10 may be of various we]l known forms such that further description thereof is not necessary to the understanding of this invention. In the preferred embodiment illustrated the bowl 24 is of a structure as shown, described and claimed in the copending Canadian Patent application Serial No. 285,048 filed August 19, 1977. Still anothe-r companion application Serial No. 282,886 filed July 15, 1977 morc fully describes, shows and claims matter relevant to this application.
The upper member of bowl 24 has a generally conical disc portion 36 which extends outwardly and downwardly from the portion thereof forming chamber 30. A formed ring member 38 is suitably removably and rigidly secured to the lower end dap/-- ¦
,, .
,, , ~
of the disc portion 36 and has an inner surface of a ~orm to provide a smooth continuation of the inner curvature of disc portion 36 and a lower surface 40, ~ig. 5, in a plane extending radially of the axis X-X. The lower member of bowl 24 also has a generally conical disc portion 42 which extends outwardly and upwardly from a lowermost cup-shaped portion 43 thereof which cup-shaped portion 43 receives the distributor-accelerator member ~6 therein. A formed ring member 44 having an upper surface 46 extending in a plane parallel to the surface 40 is supported with reference to the disc portion 42 to permit the ring member 44 to be moved axially with reference to the ring member 38 from an uppermost position whereat surfaces 40 and 46 are engaged and a lowermost position whereat surfaces 40 and 46 form the discharge opening 34 having the maximum axial extent. Ring member 44 is the uppermost portion of a piston or movable assembly which is supported for axial movement by a suitable plurality of stationary assemblies 48 suitably rigidly supported by a radial outer portion of disc portion dap/~ ' I
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-~ ,34~3 42. Surfaces 40 and 46 are circumferentially continuous and in axial alignment such that when in engagement with each other a proper seal is maintained therebetween by the assemblies 54. SurEaces ~0 and 46 can be of any suit-able cooperable configuration to provide such seal however edges 40 and 46 are preferably parallel surfaces as des-cribed to minimize resistance to the flow o~ material therebetween when the discharge opening 34 is formed.
Assemblies 48 (Fig.2) have a common seal. adaptor or formed flange 50 which extends radially outwa-rdly of the disc portion 42 and circumferentlally thereaxound with the radial inner end being suitably rigidly and removably secured to an external radial outermost portion of disc portion ~2. A plurality of circumferentially ~.
spaced circular cross section guide pins 52 are suitably rigidly and removably secured to an intermedia~e radial extent of flange 50 and extend downwardly therefrom with the centers of the guide pins 52 being on a circle coaxial with the axis X-X. Each guide pin 52 has an elongated intermediate cylinder portion 71 which portions 71 are coaxially slidably received in elongated bores in respective axially aligned bushings 72. Each bushing 72 l ~
has an upper externally threaded portion which is thread- I ;
edly received within the threaded bore of an adaptor 73 ¦
each of which adaptors 73 is suitably rigidly and removably supported within aligned bores of a circum-ferentially continuous radially inwardly extending flange portion 74 of the movable assembly 54. Suitable elongated .
springs 75, having spaced convolutions to permit the herein described movement of movable assembly 54, encompass :~234U3 .
the upper portions oE the guide pins 52, respectively, and extend axially between the lower radial extendîng surface 76 of the flange 50 and the uppermost annuiar surfaces of the bushings 72 aligned therewith respectively.
The structural por-tions of the movable assemblies 54 are circumferentially continuous with the outer end of the flange portion 74 being suitably,rigidly and removably secured to the lower end of a radial outermost axially extending sidewall portion 56. Ring member 44 is suitably rigidl.y -lO and removably secured -to the upper end of sidewall portion 56. A circumferentially continuous upper flange portion 58 extends radially inwardly of the sidewall portion 56 and overlies a radial outer extent of the circumferentially continuous Elange 50. Flange 50 has an upstanding cir-cumferentially continuous 1ange portion 59 radially in-. wardly of the radial inner end of flange portion 58 whereby a circumferentially continuous chamber 60 is formed ~`
by the axially extending radial outer surface of flange I .
portion 59, the radially extending lower surface of flange portion 68, the radial inner surface of the sidewall l, portion 56 extending axially downward from the flange , I
portion 58 and the radially extending upper surface of the , :
flange 50 radially outward of the flange portion 59.
The radial inner end of flange portion 58 is radially spaced from flange portion 59 and the radial.outer end oE
flange 50 is radially spaced from the sidewall portion 56 to provide respective upper and lower vent passageways 63a and 63b. The upper vent passageway 63a communicates with the exter:ior of the wall portion 56 by means of a sui-table plura:Lity of circum:Eerentially spaced passage~ays - . .. . ,, . ... - .- . ;. . ~ /
Z~403 !~
I
57, one of which is shown in phantom which passageways extend from passageway 63a radially through the upper `\ - flange portion 58. See also Serial No. ~ for a ' full showing of such passageway although not shown a check valve is located in the radially outer extent of each passageway 57 to prevent the entry of dirt interiorly of wall portion 56.
A control member 62 conslsting of a selectively pressurizable annular flexible tube is closely received within chamber 60 to effect controlled movement of the i ~ :
movable assembly 54. Control member 62 is pressurizable from a sui-table external pressure course through suitable supply lines such as by a suitable n~lmber of circumferen- , tially spaced tubular supply lines 67 in communication with the interior of control memher 62. Supply lines 67 extend radially inwardly and downwardly of chamber 60 through suitable openings in flange 50 and thence along the outer surface of the lower member of bowl 24 into registry with the respective open ends of circumferentially spaced passageways 64. Passageways 64 extend radially inwardly from the exterior of shaft 14 to a central I :
passageway 65 extending coaxially do~mwardly within shaft 14 with the lowermost end of passageway 65 being in i :
registry with a suitable air flow control 66 having a suitable controllable supply line 68 connected thereto.
Although any suitable fluid can be utilized to pressurize the control member 62, pressurized air is preEerred clue to its availability, the known controls for controlling air flow, and the minimal inertial effect thereof;
accordingly, air is described herein as the opera~ing ' ` `
.~ . , .
34(~3 ~ ~
fluid for the control member 62. Control 66 is of any suitable type to permit the flow of air to be controlled as described herein and suitable known fittings, not shown are u~ilized between the described portions of the air supply system.
Inasmuch as a ring member 44 noves axially with respect to the lower disc portion 42, a suitable flexible circumferentially continuous seal 70 is provided there-between. As sho~.7n, seal 70 has a vertical extent suitably captively retained between the outer circumferentlal edge of lower disc portion 42 and an axial radial innermost extent of flange portion 59 of ~lange 50 and a horizontal extent suitably captively received between a lower radially extending surface of the ring member 44 radially inward of the side portion 56 and the upper radially extending surface of flange portion 58 radially inward of the side portion 56. With such structure the knee or intermediate portion of the seal 70 is flexed or stretched when the edges 40 and 46 are in engagement and relaxed when the edges 40 and 46 are separated to ~ ~;
generally maintain the curvature of the inner surface of thelower portion of the bowl 24 in both the flexed and relaxed conditions.
Control member 62 is of any suitable configura-tion cooperable with the surfaces of chamber 60 to selectively axially position the movable assembly 54 relative to the upper portion of the bowl 24 and, as shown, is a hollow rectangular member through the extent of axial movement oE the movable assembly 54. Control member 62 is pressurlzed, as desired, Erom a controllable - ;
34c~3 source of pressurizecl air, not shown, such that air at the desired pressure flows through supply line 68, control 66> passageways 65 and 64, lines 67 to the interior of control member 62. Thus, l~ operating the centrifuge as set forth in Serial No. 285,048 the control member 62 is pressurized to force the surfaces 46 and 40 into engagement Fig. 2, and, as desired, the pressurized air is selec-tively reduced v-.a operation of the control 66 to permit the bias of springs 75 -to move -the movable assembly $4 lo axially do~nwardly -to provide the desired axial extent oE
opening 3~. The pressure of the air in control member 62 is reduced as desired by closing the supply line 68 and exhausting the pressurized air through lines 67, passageways 6~ and 65, control 66 to atmosphere or, if desired, to a recèiver by means of a flow line, not shown, connected to control 66. Since the bias of springs 75 ;
moves the movable assembly 54 axially downwardly vent lines 63a and 63b ensure that chamber 60 is vented to the atmosphere through passageways 57 to ensure there is no ; 20 back pressure on the seal 70 on the control member - 62 during any axial movement of movable assembly 5~
It will be realized that atmospheric pressure exists in the area surrounding springs 75 notwithstanding the circumferenkial continuity of the structural members 44, 56, 58 and 74 of the movable assembly 54. 1 :~
Since the control member 62 axially overlies ~:
the springs 75 and each is effective between the flange 50 and the movable assembly 54 as described, the control member 62 and spring 75 comprise a variable force system for actuating the movable assem~ly 54. Thus, springs 7S
-~ ~3~ ~ 3 - provide a constant bias urging the movable assembly 54 do~nward such that gap 34 is formed and control member 62 is selectively actuatable to overcome the bias o~ the springs 75 to any selected degree depending upon the air pressure therein; whereby tl~e gap 34 is of any axial extent as desired within the limit of the axial travel of the movable assembly 54, or, if desired gap 34 can be elimina-~ed by forcing surfaces 46-40 into engagement.
Since springs 75 and control member 62 prod~lce oppositely directed axial forces on the movable assembly 5~; the bias force of the springs 75, the areas upon which the control member 62 is effective to produce movement of the movable assembly 54, and the air supply pressure are selected to provide such described movement of the movable assembly 54. By providing the described bias of springs 75 the position of surface 46 relative to surface 40 can be calibrated with-reference to the air pressure within control member 62; i.e. for a given air pressure in con-trol member 62 a known width of discharge opening 3~ is obtained. Springs 75 can, if desired, be eliminated ~ ~ ;
ho~ever the same positive control of the width of gap 34 is not necessarily obtained since the effect of the bias force of springs 75 is also eliminated. Also, by redesign, the directions of the described forces of the m-~able assembly 54 can be reversed by relocating the springs 75 and the control member 62.
With the movable assembly 54 described the bias of each spring 75 is selectively adiustable by axially positioning thelower end of a spring 75 relative to the movable assembly 54 by axially positior.ing bushing 72 .:
3~3 . .
with respect to the threaded bore of the adaptor 73.
Also a suitable lock nut 77 is provided which threadedly engages the external threads of the bushing 72 and the lower radial surface o~ adaptor 73 whereby a selected relative axial position of bushing 72 and adaptor 73 can be maint~ined. A suitably ~ormed cap member 78 is secured to the lower end of bushing 72 to prevent dirt and the like from enter;ng the movable assembly 54 and interfering with the operation thereof. ~urther a suiLable flexible member 79 is suitably securecl to the flange portion 74 and the lower portion of bowl ~4 which extends circumferentially therearound to prevent dirt from entering the movable assembly 54 from the underside of the centrifuge. If desired, and preferably, the lower end of each guide pin 52 has a lowermost axially extending threaded stem 81 which carries an axially adjustable nut 82 having an integral or separate washer or stop 83 extending radially outwardly from the upper surface of the nut 82. Stops 83 are located in the path of movement of the bushings 72, respectively, such that upon movement of the mouable assembly 54 downwardly under the bias of springs 75 the lowermost position of the bushings 72 engage the stops 83 at a known preselected axial location to provide a discharge opening 34 of a known a~ial length.
A fixed maximum opening 34 is particularly desired in instances where the material discharged by the centrifuge is normally of the same composition. The heretofore described structure ~or controlling the material discharge has many substantial advantages. As known, during opera-tion of a centrifuge the material within the centrifuge ,.
- , , " i, ~",. . , , ~ , ~"
3~3 . . l exerts a pressure on the inner surface area of ring member 44 tending to shift the central axis of the ring member 44. By providing a circumferentially continuous ring member 4~ with the central axis of ring member 44 concentric with axis X-X such forces tend to be ba~anced to maintain such concentricity. Since the control member 63 is inflated from an external pressure source the size of the discharge opening 3~ is controllable independen-tly of the s~eed and/or density of the materia]
within the bowl 2~.
Another advantage of the structure descrihed is that the stationary assembly 48 and the movable assembly 54 can be removed from the lower portion of the bowl 24 and assembly 54 can be removed from assembly 48 to facilitate the replacement of worn components. Further, by the described adjustment of the bias of springs 75 the ring member ~4 can be properly located with respect to the ring member 38 notwithstanding the minor variations -in the structure of assemblies 48 and 54 as occur in man- ;
ufacturing. Also, the bias of springs 75 can be adjus~ed externally of the centrifuge. A particular advantage is that the surfaces upon which forces are produced to move the assembly 54 are simple planar contact areas which do not require precision machinery. Also, by unîform cir-cumferential spacing of pins 52 and a long engagement area between cylinder portions 71 and the bores of bushings 72 concentricity is maintained between the movable assembly and the axis X-X. The large bearing area of portion 71 and bushings 72 are readily machined to thetolerances required to maintain such concentricity ~ ~lZ34(~3 inasmuch as they are simply cylindrical surfaces. The control member 62 eliminates the necessity of any seals between assemblies ~8 and 5~ and since control member 62 is encompassed by the surfaces of chamber 60, as the areas of vent passages 63a and 63b are minimal 9 the control member 62 need only be of a strength to prevent rupture or wear of a captive member as compared to the rupture or wear strength required of an unsupporLed member.
In order to control the slurry input flow in accordance with the principles of this invention the distributor accelerator 26 is not of a form to accelerate the incoming slurry to the desired velocity ~or entering the bowl 24, to discharge the accelerated slurry at a desired selected direction relative to the bowl 24, and to provide a back pressure on the incoming slurry inde-pendently of the pressure existing within the bowl 24.
The distributor accelerator 26 is also preferably a replaceable member. In accomplishing such purposes the distributor accelerator 26 can be of various struc- I -tures with the structure of Fig. 3 being presently pre-ferred. In such embodiment,the distributor accelerator 26 is a unitary formed structure of generally rectangular cross section which extends circum-Eerentially aroundthe shaft 1 outwardly adjacent the discharge ports 28 and has a formed flow passageway extending radially therethrough.
The lowermost surface of the distributor-accelerator 26 e~tends radially outwardly and the radial outermost surface thereof extends axially upwardly from the lower-most surface to provide suitable outer surfaces which are closely received in the lower cup shaped portion 43.
~3~3 Distributor-accelerator 26 is suitably secured to the portion 43 in any suitable manner such as by removable threaded fasteners S extending radially through the cup-shaped portion ~3 into engagement with the ou-t~r axially extending surface of distributor accelerator 26.
The flow passageway through the distributor accelerator 26 has four sequential portions with the lowermost portion being a slurry inlet 7~ in fluid.
co~unication with the discharge ends of ports 28, an accelerating portion having a passageway extending axially therethrough from the inlet 7 wi~h circumfer entially spaced vanes 9 extending radially thereacross to accelerate the slurry, a nozzleportion having a nozzle passageway 11 extending axially upwardly and radially inwardly from the upper edges of the vanes 9 and a discharge portion having a through passageway 13 there- :
in to direct the slurry into the bowl 24. Inlet 7 is an open sided and upwardly open circumferentially continuous volume which receives the slurry from the ports 28 and provide the required slurry flow to the vanes 9. Inlet ' 7 is of a volume below the vanes 9 to provide a flow of slurry to the passageway in which the vanes 9 are located with a minimum of pressure head loss. The accelerating porton comprises a passageway having a suitable number of radially extending vanes 9 therein which are o an axial length to provide the desired acceleration of the slurry at a rate to provide the proper supply of the slurry to the bowl 2~ and are preferably of a suitable impeller type as is known for accelerating fluids. The nozzle passageway 11 is circumferentially continuous , ~a403 and i5 of a convergent type having its inlet immediately adjacent and in fluid flow communication with the passageway having vanes 9 there-in. The flow axis of the nozzle passageway 11 extends at a convergent angle with respect to the axis X~X. In order to prov;de such radial inward inclination of the nozzle passageway 11 the radially inner surface of passageway 11 is formed on a , j ring portion 15 which encompasses the shaft 14 and ex-tends axially do~mwardly from the lower end of the dis--lO charge passageway 13 to the lower end o~ the accelerator portion with the radially inner ends o~ ~anes ~ termina-ting at the radially outermost surface of the ring por-tion 15 below the passageway 11. The lower edgesof the vanes 9 and the ring portion 15 are located in the axial upper plane of the slurry inlet 7. The nozzle passageway 11 is of a converging configuration such that the pressure of the slurry at the inlet and.the pressure of the slurry at the throat is maintained at a ratio with reference to the parameters affecting fluid flow through the nozzle passageway, to ensure that he pressure required to supply slurry to the slurry inlet 7 is independent of the pressure existing in the bowl 24, i.e. the characteris- I ~
tics of the distributor accelerator 26 establishes the I ;
pump pressure required to pump the slurry to the slurry inlet 7. In addition, the nozzle passageway 11 is in-clined radially inwardly towards the axis X-X at an angle such that the slurry has the desired rotational I :
velocity upon entering the discharge passageway 13. It is to be realized that the rotational velocity o~ the slurry within the slurry inlet 7 is dependent upon the . .
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desi.red rotation o~ the bowl 24 since the distributor accelerator 26 is integral with thebowl 24. In view of the slippage occurring withi.n the distributor-accelera-tor 26 the angular velocity of the slurry is subject to being reduced. Accordingly, the passage-way 11, by being inclined towards the shaft 14, increases the angular velocity of the slurry as it traverses passageway 11 to provide the desired angular velocity of ~he sltlrry at the entrance of the discharge passageway-13 and at the entrance of the bowl 24.
The discharge passageway 13 is circumferen-tially continuous and formed by the otlter surface of the shaft 14 and a surface on the upper por-tion of the distribiltor accelerator 26 and provides a through passageway to introduce the slurry into the bowl 24 at a velocity such that there is a minimum of turbulence ~ I
between the slurry entering the bowl 24 and the material already within the bowl 24. Accordingly, the slurry is discharged from the discharge passageway 13 with -an angular velocity as close as feasible to the angular velocity of the material within the bowl 24 and with an axial velocity as close as feasible to the axial velocity of the material in the bowl 24. For such purposes, the flow axis of the discharge passageway 13 of Fig. 3 is a parallel sided passageway extending axially upwardly ~ :
and slightly radially outwardly to discharge at the radial innermost portion of the bowl 24. Since there are certain changes in the pressure and the angular velocity of the slurry within the discharge passageway due to such inclination the design of the nozzle passageway 11 is , .. , ....... .~.
.l ~239c~3 selected with reference t.o such changes. Distributor-accelerator 26 has an upper surface which is a continua-tion of the curvature of the inner surface of the lower disc portion 42 so tha~ the desired separation as set forth in Serial No. 285,048 is obtained. In selecting the desired discharge veIocity from the discharge passageway 13 the portion of the shaft 14 forming one side of passageway is axially dowmwardly -tapered through the axial length of the discharge passageway 13. In 1~ the embodiment of Fig. 3 the various surfaces o~ the distributor-accelerator 25 which are inclined with respect to the axis X-X have apexes which are coincident ~ith the axis X-X. If desired the outer surface of the passageway in which the vanes 9 are located may be provided with an axial taper.
The distributor-accelerator shown in Figs. 3 ~ ~
and 4 are replaceable by providing access through the ~ I
housing 16, which access is not shown to permit the lower disc 22 to be removed from the shaft 14 and there-after by releasing fasteners 5, inserting a new dis-tributor accelerator. -Shaft 14 has one or more ports 28 to provide a - continuous supply of slurry to the inlet 7 to continu-ously maintain the inlet 7 full of slurry. Preferably, a plurality of ports 28 are provided to supply slurry to circumferentially spaced portions of the inlet 7. As more fully set forth in Serial No. 285,048 the slurry is separated wi-thin the bowl 24 with a resultant dis-chargeable product constituent, that is, the higher denisty portion of the separated slurry being centri-I
fugally moved to the outer portion of the bowl 2~.
The dischargeable product portion moves relative to the bowl 24, however, such movement towards the discharge opening of the bowl 2~ with the dischargeable portion having, as a general proposition a rotational velocity substantially the same as or slightly less than the Z
rotational velocity of the bowl 2~ and little axial velocity within bowl 2~. The effluent constituent, that is, the lower density portion of the separated slurry, has a high ~ater content relative to the product portion and is discharge~ from the bowl 2~
through ports 32. Thus, the slurry in the separation zone of the bowl 2~ must have an axial velocity to main-tain the discharge and a rotational velocity to maintain the rate of despositing of material in th2 product por-- tion. Inasmuch as the slurry is separated into the product constituent and the effluent constituent within the separating zone the axial and rotational velocities of the slurry in the separation zone are not, as a general proposition, equal to the axial and rotational velocities of the constituents. It is to ~e recognized that there are many factors which effect the velocities of the constituents as are known in the art. In Z
accordance with the present invention for ~nown opera-ting parameters the slurry is introduced into the separa-ting zone with the rotational velocity being as close as feasible to the rotational velocity of the prod-lct const:ituent and with the axial velocity being as close as feasible to the axial velocity required to maintain the desired discharge rate of the effluent. By :
. . ~ -so introducing the slurry with such velocities an improved separation of the slurry is obtained i~ that there is a minimtlm of turbulence created within the separating zone between the incoming slurry and the ::
deposited product constituent so that the inner surface of the product constituent is mot eroded by the incoming slurry to cause the product constituent to be re-entrained into the separating zone.
With the distributor-accelerator 26 being as described and of the ~orm as sho~, the vanes 9rotate at the same angular velocity as the bowl 2~ inasmuch as vanes 9 are integral therewith. Accordingly, vanes 9 :
receive the slurry from the inlet 7 and accelerate the ! ' slurry such that the slurry has a given rotational velocity at the discharge end of the vanes 9 which is not necessarily the angular velocity desired for intro- I `
ducing the slurry into the separation zone of the bowl 24. Since passageway 11 converges towards the axis X-X --;
the rotational velocity of the slurry increases within :~
passageway 11. The resultant rotational velocity o~ ¦ :
the slurry is at a value with relation to any decrease ~I.
in rotationalvelocity within passageway 13 such that the I :
slurry enters separating zone with substantially the same rotational velocity as the deposited material within :~
the bowl 24. Thus vanes 9 increase the hydrostatic pressure within the slurry to a value necessary to pro-vide the required volume flow of slurry to the separating zone through the passageways 11 and 13 at substantially `~
the rotationalvelocity o~ the bowl 2~. The discharge passageway 13 has an axial extent such that the axial I ;
.
- . ~. . . .
~2~ 3 - velocity at discharge is at the value required to obtain the desired rate of ~low through the discharge ports 28.
The axial extent of passageway 13 is of a con~iguration to compensate for any gain or loss of rotational velocity - o the slurry in passageway 11. The width and length of passageway 13 are also selected to obtain the desired axial androtational velocity of the slurry as it is dis- -charged into the separation zone.
In designing a distributor-accelerator 26 the axial and rotational velocities of -the constituen-ts within the bowl 24 determine the value that is desired for the axial and-rotational velocities of the slurry for its intro-duction into the separation zone. Thus, the distributor-accelerator 26 is designed with reference to the operating parameters known or described; however, once the configura-tion of the distributor-accelerator 26 is established the pressure of the slurry as it is introduced into the separating zone is determined by the distributor- I ~
accelerator 26 independently of the actual value of the l ;
axial and rotational velocities of the constituents.
Fig. 4 illus-trates another distributor-accelerator 26' construed in accordance with the principles of this invention which is similar to the distributor-accelerator 26 of Fig. 3 except that the nozzle passageway I ~
11 of Fig. 3 has been eliminated and an intermediate ¦ ~, chamber provided between the accelerator vanes 9 and the discharge passageway 13. With such construction the nozzle portion is replaced by a chamber 17 into which the accelerated slurry is discharged by the vanes 9. A ring portion 15' is provided similar to ring portion 15 except ~-1 ~2341?;~
that the portion thereof above the vanes 9 is eliminated.
The slurry inlet 7 is of the same configuration as - -described; however, the lower ancl outer walls thereof are formed by the cup-shaped portion 43' which is similar to cup-shaped portion 43 previously described except for the structural changes required to form inlet 7. The chamber 17 provides a decreasing pressure head on the slurry therein in the axially up~ard direction above the vanes 9 such that the pressure of the material within the bowl 2~ does not establish the back pressure on the slurry in the inlet 7. Chamber 17 does have a more turbulent slurry flow therein than nozzle portion of Fig. 3 however, such turbulence can be accepted if desired.
though the flow of slurry through dis~ributor-accelerator 26' differs from the flow of slurry through the distributor-accelerator 26 each structure provides the desired axial and rotational velocities to the slurry as described. I ; Although preferred embodiments of this invention have been described in accordance with the Patent Statutes those skilled in the art to which this invention relates will re,alize that various modifications can be made to the structures described without departing from the spirit and scope of the invention. Accordingly, the claims hereto are to be construed in accordance with the knowledge of one skilled in tht art to which the inventi~n relates.
-2~-. .
The aforementioned problems with respect to controlling the discharge of material from the separating bowl of a centrifuge are overcome by the invention of the parent application which broadly defines a centrifuge comprising: an elongated shaft member rotatable about the longitudinal central axis thereof, a bowl member having formed portions rigidly secured to axially spaced portions of the shaft member, respectively, the formed portions extending radially outwardly of and circumferentially encompassing the central axis to form a chamber therebetween, one of the formed portions having with respect to the axis a separate radially outermost annular segment which is axially movable from a closed position in engagement with a circum-ferentially extending outer peripheral section of the other of the formed portions to an open position axially spaced from the outer peripheral section to form a material discharge opening ~ i~
solely between the annular segment and the outer peripheral section, at least one of the members having means for introducing a slurry into the bowl member, the bowl member having means for discharging an effluent constituent of the slurry, and actuator means cooperably connected to the one of the formed portions and the annular segment for selectively axially positioning the annular segment.
On the other hand the problems relating to prior art distributor-accelerators as enumerated above are overcome by the present invention which broadly provides a centrifuge comprising:
sd ~
~ 3 an elongated upstanding shaft rotatable about -the longitudinal central axis thereof; a bowl member having upper and lower formed portions secured to axially spaced portions of the shaft, respectively, for conjoint rotation therewith; the bowl member forming a chamber for centrifugally separating a slurry into a product constituent in a radially, with respect to the axis, outer portion of the bowl member and an efEluent constituent at a portion of the bowl member radially inward of the product con-stituent; the bowl member having means for discharging such constituents therefrom; the lower formed portion having a lower-most section with a formed through passageway therein having, relative to the axis, an axial extent with the axially uppermost ena thereof being in open communication with the interior of the bowl member, the shaft having a passageway therein for receiving a slurry and for discharging the slurry to an axially lower portion of the passageway, the lower portion of the passageway having, relative to the axis, a circumferentially and radially outermost extent located radially outward of the uppermost end;
and, the passageway having means to control the rotational velocity of a slurry flowing through the passageway. . : ~.
Furthermore the present invention can be seen as also providing a method of controlling the axial and rotational velocity of a slurry continuously supplied to a rotary bowl centrifuge rotatable abou-t an axis wherein the slurry is supplied through an elongated passageway in the bowl and subsequently separated in the bowl into a product constituent located within and discharged from a radial outer portion of the bowl and an effluent constituent located radially inwardly of the product constituent and discharged therefrom comprising, initially simul-taneously rotationally accelerating and increasing the hydrostatic pressure of an incoming slurry with such a passageway, immediately after such initial accelerating further increasing the rotational velocity of such a slurry with such passageway by having such sd/~ _4_ slurry flow towards -the axis, and immediately after such further rotational acceleration discharging such a slurry from such passageway into the interior of such a rotary bowl at a rotational velocity substantially equal to rotational velocity of such a product constituent.
These and other features of this invention will be bet-ter understood upon consideration of the following detailed descrip-tion of presently preferred embodiments thereof taken in con-junction with the following drawings r wherein:
Fig. 1 is a cross-sectional view with portions there-of in side elevation of a centrifuge apparatus constructed in accordance with the principles of this invention;
Fig. 2 is an enlarged cross-sectional view with sd/~ -4A-.,, : :.- .
~.~lZ34~3 .
.~' . . ', portions thereof in side elevation of a material discharge control mechanism as shown in Fig. l;
Fig. 3 is an enlarged cross sectional view of the distributor-accelerator structure as shown in Fig. l;
Fig. 4 is a view similar to Fig. 3 o:f another embodiment of a distributor-accelerator constructed in accordance with the principles of this invention, and Fig. 5 is an enlarged view in the open position of the structure forming the discharge opening of the apparatus as shown in Fig. 1. .
Centrifuges of the rotary bowl type are well kno~n in the art. The rotary bowl centri:Euge shown in Fig. 1 comprises a stationary formed housing 10 having vertically spaced and aligned bearings 12 for supporting an elongated sha~t 14 for rotation about its vertical rotation axis X-X. In the description herein the term radial and circumferential is with reference to the rotation axis ~-X, the term axial is with reference to the rotation axis X--X, or any axis parallel thereto, and the terms upper and lower and the like are used for convenience in this descriptio~ 1 with respect to the showing o~ the figures herein. Sha~t ¦ ;
14 is suitably rotationally driven by means of a controll-able motor (not shown) having drive belts 16 cooperable with a pulley 18 rigidly secured to the shaft 14 upwardly adjacent the housing 10. Shaft 14 is provided with a central vertically extending passageway 20 therein with the upper end being open and cooperable with a feed pipe assembly 22 to supply the material, i.e. the slurry, to be separated in the centrifuge. A separation chamber or ~0 bowl 2L~, comprising formed upper and lower members, is suitably rigidly secured to shaft 14 to rotate therewith within housing 10. The lowermost portion of the bowl 24 ha~s a distributor-accelerator member 26 which member 26 l~as an interior passageway in open communication with ports 28 extending laterally and downwardly from the inner end of passageway 20.
Bowl 24 has an uppermost central annular chamber 30 encompass-ing the upper portion of the shaft 14 with circumferentially spaced discharge ports 32 extending upwardly and outwardly of the chamber 30 and in open fluid communication therewith.
~laterial is discharged from the bowl 24 through ports 32 with the flow thereof being suitably directed within housing 10 by suitable means.
- In operation the mixture to be subjected to centrifugal - action of the centrifuge is introduced through the feed pipe `
- assembly 22 and thereafter flows through passageway 20, ports 28, member 26 into bowl 24 in which the mixture is separated ~ith the low density fraction thereof being discharged through the ports 32 and with the high density fraction thereof being discharged through the discharge opening 34 (Fig. 5). For the purposes of this invention the construction of the feed pipe assembly 22, drive pulley 18, bearings 12, shaft 14, discharge ports 32 and housing 10 may be of various we]l known forms such that further description thereof is not necessary to the understanding of this invention. In the preferred embodiment illustrated the bowl 24 is of a structure as shown, described and claimed in the copending Canadian Patent application Serial No. 285,048 filed August 19, 1977. Still anothe-r companion application Serial No. 282,886 filed July 15, 1977 morc fully describes, shows and claims matter relevant to this application.
The upper member of bowl 24 has a generally conical disc portion 36 which extends outwardly and downwardly from the portion thereof forming chamber 30. A formed ring member 38 is suitably removably and rigidly secured to the lower end dap/-- ¦
,, .
,, , ~
of the disc portion 36 and has an inner surface of a ~orm to provide a smooth continuation of the inner curvature of disc portion 36 and a lower surface 40, ~ig. 5, in a plane extending radially of the axis X-X. The lower member of bowl 24 also has a generally conical disc portion 42 which extends outwardly and upwardly from a lowermost cup-shaped portion 43 thereof which cup-shaped portion 43 receives the distributor-accelerator member ~6 therein. A formed ring member 44 having an upper surface 46 extending in a plane parallel to the surface 40 is supported with reference to the disc portion 42 to permit the ring member 44 to be moved axially with reference to the ring member 38 from an uppermost position whereat surfaces 40 and 46 are engaged and a lowermost position whereat surfaces 40 and 46 form the discharge opening 34 having the maximum axial extent. Ring member 44 is the uppermost portion of a piston or movable assembly which is supported for axial movement by a suitable plurality of stationary assemblies 48 suitably rigidly supported by a radial outer portion of disc portion dap/~ ' I
.,~, . I . I
-~ ,34~3 42. Surfaces 40 and 46 are circumferentially continuous and in axial alignment such that when in engagement with each other a proper seal is maintained therebetween by the assemblies 54. SurEaces ~0 and 46 can be of any suit-able cooperable configuration to provide such seal however edges 40 and 46 are preferably parallel surfaces as des-cribed to minimize resistance to the flow o~ material therebetween when the discharge opening 34 is formed.
Assemblies 48 (Fig.2) have a common seal. adaptor or formed flange 50 which extends radially outwa-rdly of the disc portion 42 and circumferentlally thereaxound with the radial inner end being suitably rigidly and removably secured to an external radial outermost portion of disc portion ~2. A plurality of circumferentially ~.
spaced circular cross section guide pins 52 are suitably rigidly and removably secured to an intermedia~e radial extent of flange 50 and extend downwardly therefrom with the centers of the guide pins 52 being on a circle coaxial with the axis X-X. Each guide pin 52 has an elongated intermediate cylinder portion 71 which portions 71 are coaxially slidably received in elongated bores in respective axially aligned bushings 72. Each bushing 72 l ~
has an upper externally threaded portion which is thread- I ;
edly received within the threaded bore of an adaptor 73 ¦
each of which adaptors 73 is suitably rigidly and removably supported within aligned bores of a circum-ferentially continuous radially inwardly extending flange portion 74 of the movable assembly 54. Suitable elongated .
springs 75, having spaced convolutions to permit the herein described movement of movable assembly 54, encompass :~234U3 .
the upper portions oE the guide pins 52, respectively, and extend axially between the lower radial extendîng surface 76 of the flange 50 and the uppermost annuiar surfaces of the bushings 72 aligned therewith respectively.
The structural por-tions of the movable assemblies 54 are circumferentially continuous with the outer end of the flange portion 74 being suitably,rigidly and removably secured to the lower end of a radial outermost axially extending sidewall portion 56. Ring member 44 is suitably rigidl.y -lO and removably secured -to the upper end of sidewall portion 56. A circumferentially continuous upper flange portion 58 extends radially inwardly of the sidewall portion 56 and overlies a radial outer extent of the circumferentially continuous Elange 50. Flange 50 has an upstanding cir-cumferentially continuous 1ange portion 59 radially in-. wardly of the radial inner end of flange portion 58 whereby a circumferentially continuous chamber 60 is formed ~`
by the axially extending radial outer surface of flange I .
portion 59, the radially extending lower surface of flange portion 68, the radial inner surface of the sidewall l, portion 56 extending axially downward from the flange , I
portion 58 and the radially extending upper surface of the , :
flange 50 radially outward of the flange portion 59.
The radial inner end of flange portion 58 is radially spaced from flange portion 59 and the radial.outer end oE
flange 50 is radially spaced from the sidewall portion 56 to provide respective upper and lower vent passageways 63a and 63b. The upper vent passageway 63a communicates with the exter:ior of the wall portion 56 by means of a sui-table plura:Lity of circum:Eerentially spaced passage~ays - . .. . ,, . ... - .- . ;. . ~ /
Z~403 !~
I
57, one of which is shown in phantom which passageways extend from passageway 63a radially through the upper `\ - flange portion 58. See also Serial No. ~ for a ' full showing of such passageway although not shown a check valve is located in the radially outer extent of each passageway 57 to prevent the entry of dirt interiorly of wall portion 56.
A control member 62 conslsting of a selectively pressurizable annular flexible tube is closely received within chamber 60 to effect controlled movement of the i ~ :
movable assembly 54. Control member 62 is pressurizable from a sui-table external pressure course through suitable supply lines such as by a suitable n~lmber of circumferen- , tially spaced tubular supply lines 67 in communication with the interior of control memher 62. Supply lines 67 extend radially inwardly and downwardly of chamber 60 through suitable openings in flange 50 and thence along the outer surface of the lower member of bowl 24 into registry with the respective open ends of circumferentially spaced passageways 64. Passageways 64 extend radially inwardly from the exterior of shaft 14 to a central I :
passageway 65 extending coaxially do~mwardly within shaft 14 with the lowermost end of passageway 65 being in i :
registry with a suitable air flow control 66 having a suitable controllable supply line 68 connected thereto.
Although any suitable fluid can be utilized to pressurize the control member 62, pressurized air is preEerred clue to its availability, the known controls for controlling air flow, and the minimal inertial effect thereof;
accordingly, air is described herein as the opera~ing ' ` `
.~ . , .
34(~3 ~ ~
fluid for the control member 62. Control 66 is of any suitable type to permit the flow of air to be controlled as described herein and suitable known fittings, not shown are u~ilized between the described portions of the air supply system.
Inasmuch as a ring member 44 noves axially with respect to the lower disc portion 42, a suitable flexible circumferentially continuous seal 70 is provided there-between. As sho~.7n, seal 70 has a vertical extent suitably captively retained between the outer circumferentlal edge of lower disc portion 42 and an axial radial innermost extent of flange portion 59 of ~lange 50 and a horizontal extent suitably captively received between a lower radially extending surface of the ring member 44 radially inward of the side portion 56 and the upper radially extending surface of flange portion 58 radially inward of the side portion 56. With such structure the knee or intermediate portion of the seal 70 is flexed or stretched when the edges 40 and 46 are in engagement and relaxed when the edges 40 and 46 are separated to ~ ~;
generally maintain the curvature of the inner surface of thelower portion of the bowl 24 in both the flexed and relaxed conditions.
Control member 62 is of any suitable configura-tion cooperable with the surfaces of chamber 60 to selectively axially position the movable assembly 54 relative to the upper portion of the bowl 24 and, as shown, is a hollow rectangular member through the extent of axial movement oE the movable assembly 54. Control member 62 is pressurlzed, as desired, Erom a controllable - ;
34c~3 source of pressurizecl air, not shown, such that air at the desired pressure flows through supply line 68, control 66> passageways 65 and 64, lines 67 to the interior of control member 62. Thus, l~ operating the centrifuge as set forth in Serial No. 285,048 the control member 62 is pressurized to force the surfaces 46 and 40 into engagement Fig. 2, and, as desired, the pressurized air is selec-tively reduced v-.a operation of the control 66 to permit the bias of springs 75 -to move -the movable assembly $4 lo axially do~nwardly -to provide the desired axial extent oE
opening 3~. The pressure of the air in control member 62 is reduced as desired by closing the supply line 68 and exhausting the pressurized air through lines 67, passageways 6~ and 65, control 66 to atmosphere or, if desired, to a recèiver by means of a flow line, not shown, connected to control 66. Since the bias of springs 75 ;
moves the movable assembly 54 axially downwardly vent lines 63a and 63b ensure that chamber 60 is vented to the atmosphere through passageways 57 to ensure there is no ; 20 back pressure on the seal 70 on the control member - 62 during any axial movement of movable assembly 5~
It will be realized that atmospheric pressure exists in the area surrounding springs 75 notwithstanding the circumferenkial continuity of the structural members 44, 56, 58 and 74 of the movable assembly 54. 1 :~
Since the control member 62 axially overlies ~:
the springs 75 and each is effective between the flange 50 and the movable assembly 54 as described, the control member 62 and spring 75 comprise a variable force system for actuating the movable assem~ly 54. Thus, springs 7S
-~ ~3~ ~ 3 - provide a constant bias urging the movable assembly 54 do~nward such that gap 34 is formed and control member 62 is selectively actuatable to overcome the bias o~ the springs 75 to any selected degree depending upon the air pressure therein; whereby tl~e gap 34 is of any axial extent as desired within the limit of the axial travel of the movable assembly 54, or, if desired gap 34 can be elimina-~ed by forcing surfaces 46-40 into engagement.
Since springs 75 and control member 62 prod~lce oppositely directed axial forces on the movable assembly 5~; the bias force of the springs 75, the areas upon which the control member 62 is effective to produce movement of the movable assembly 54, and the air supply pressure are selected to provide such described movement of the movable assembly 54. By providing the described bias of springs 75 the position of surface 46 relative to surface 40 can be calibrated with-reference to the air pressure within control member 62; i.e. for a given air pressure in con-trol member 62 a known width of discharge opening 3~ is obtained. Springs 75 can, if desired, be eliminated ~ ~ ;
ho~ever the same positive control of the width of gap 34 is not necessarily obtained since the effect of the bias force of springs 75 is also eliminated. Also, by redesign, the directions of the described forces of the m-~able assembly 54 can be reversed by relocating the springs 75 and the control member 62.
With the movable assembly 54 described the bias of each spring 75 is selectively adiustable by axially positioning thelower end of a spring 75 relative to the movable assembly 54 by axially positior.ing bushing 72 .:
3~3 . .
with respect to the threaded bore of the adaptor 73.
Also a suitable lock nut 77 is provided which threadedly engages the external threads of the bushing 72 and the lower radial surface o~ adaptor 73 whereby a selected relative axial position of bushing 72 and adaptor 73 can be maint~ined. A suitably ~ormed cap member 78 is secured to the lower end of bushing 72 to prevent dirt and the like from enter;ng the movable assembly 54 and interfering with the operation thereof. ~urther a suiLable flexible member 79 is suitably securecl to the flange portion 74 and the lower portion of bowl ~4 which extends circumferentially therearound to prevent dirt from entering the movable assembly 54 from the underside of the centrifuge. If desired, and preferably, the lower end of each guide pin 52 has a lowermost axially extending threaded stem 81 which carries an axially adjustable nut 82 having an integral or separate washer or stop 83 extending radially outwardly from the upper surface of the nut 82. Stops 83 are located in the path of movement of the bushings 72, respectively, such that upon movement of the mouable assembly 54 downwardly under the bias of springs 75 the lowermost position of the bushings 72 engage the stops 83 at a known preselected axial location to provide a discharge opening 34 of a known a~ial length.
A fixed maximum opening 34 is particularly desired in instances where the material discharged by the centrifuge is normally of the same composition. The heretofore described structure ~or controlling the material discharge has many substantial advantages. As known, during opera-tion of a centrifuge the material within the centrifuge ,.
- , , " i, ~",. . , , ~ , ~"
3~3 . . l exerts a pressure on the inner surface area of ring member 44 tending to shift the central axis of the ring member 44. By providing a circumferentially continuous ring member 4~ with the central axis of ring member 44 concentric with axis X-X such forces tend to be ba~anced to maintain such concentricity. Since the control member 63 is inflated from an external pressure source the size of the discharge opening 3~ is controllable independen-tly of the s~eed and/or density of the materia]
within the bowl 2~.
Another advantage of the structure descrihed is that the stationary assembly 48 and the movable assembly 54 can be removed from the lower portion of the bowl 24 and assembly 54 can be removed from assembly 48 to facilitate the replacement of worn components. Further, by the described adjustment of the bias of springs 75 the ring member ~4 can be properly located with respect to the ring member 38 notwithstanding the minor variations -in the structure of assemblies 48 and 54 as occur in man- ;
ufacturing. Also, the bias of springs 75 can be adjus~ed externally of the centrifuge. A particular advantage is that the surfaces upon which forces are produced to move the assembly 54 are simple planar contact areas which do not require precision machinery. Also, by unîform cir-cumferential spacing of pins 52 and a long engagement area between cylinder portions 71 and the bores of bushings 72 concentricity is maintained between the movable assembly and the axis X-X. The large bearing area of portion 71 and bushings 72 are readily machined to thetolerances required to maintain such concentricity ~ ~lZ34(~3 inasmuch as they are simply cylindrical surfaces. The control member 62 eliminates the necessity of any seals between assemblies ~8 and 5~ and since control member 62 is encompassed by the surfaces of chamber 60, as the areas of vent passages 63a and 63b are minimal 9 the control member 62 need only be of a strength to prevent rupture or wear of a captive member as compared to the rupture or wear strength required of an unsupporLed member.
In order to control the slurry input flow in accordance with the principles of this invention the distributor accelerator 26 is not of a form to accelerate the incoming slurry to the desired velocity ~or entering the bowl 24, to discharge the accelerated slurry at a desired selected direction relative to the bowl 24, and to provide a back pressure on the incoming slurry inde-pendently of the pressure existing within the bowl 24.
The distributor accelerator 26 is also preferably a replaceable member. In accomplishing such purposes the distributor accelerator 26 can be of various struc- I -tures with the structure of Fig. 3 being presently pre-ferred. In such embodiment,the distributor accelerator 26 is a unitary formed structure of generally rectangular cross section which extends circum-Eerentially aroundthe shaft 1 outwardly adjacent the discharge ports 28 and has a formed flow passageway extending radially therethrough.
The lowermost surface of the distributor-accelerator 26 e~tends radially outwardly and the radial outermost surface thereof extends axially upwardly from the lower-most surface to provide suitable outer surfaces which are closely received in the lower cup shaped portion 43.
~3~3 Distributor-accelerator 26 is suitably secured to the portion 43 in any suitable manner such as by removable threaded fasteners S extending radially through the cup-shaped portion ~3 into engagement with the ou-t~r axially extending surface of distributor accelerator 26.
The flow passageway through the distributor accelerator 26 has four sequential portions with the lowermost portion being a slurry inlet 7~ in fluid.
co~unication with the discharge ends of ports 28, an accelerating portion having a passageway extending axially therethrough from the inlet 7 wi~h circumfer entially spaced vanes 9 extending radially thereacross to accelerate the slurry, a nozzleportion having a nozzle passageway 11 extending axially upwardly and radially inwardly from the upper edges of the vanes 9 and a discharge portion having a through passageway 13 there- :
in to direct the slurry into the bowl 24. Inlet 7 is an open sided and upwardly open circumferentially continuous volume which receives the slurry from the ports 28 and provide the required slurry flow to the vanes 9. Inlet ' 7 is of a volume below the vanes 9 to provide a flow of slurry to the passageway in which the vanes 9 are located with a minimum of pressure head loss. The accelerating porton comprises a passageway having a suitable number of radially extending vanes 9 therein which are o an axial length to provide the desired acceleration of the slurry at a rate to provide the proper supply of the slurry to the bowl 2~ and are preferably of a suitable impeller type as is known for accelerating fluids. The nozzle passageway 11 is circumferentially continuous , ~a403 and i5 of a convergent type having its inlet immediately adjacent and in fluid flow communication with the passageway having vanes 9 there-in. The flow axis of the nozzle passageway 11 extends at a convergent angle with respect to the axis X~X. In order to prov;de such radial inward inclination of the nozzle passageway 11 the radially inner surface of passageway 11 is formed on a , j ring portion 15 which encompasses the shaft 14 and ex-tends axially do~mwardly from the lower end of the dis--lO charge passageway 13 to the lower end o~ the accelerator portion with the radially inner ends o~ ~anes ~ termina-ting at the radially outermost surface of the ring por-tion 15 below the passageway 11. The lower edgesof the vanes 9 and the ring portion 15 are located in the axial upper plane of the slurry inlet 7. The nozzle passageway 11 is of a converging configuration such that the pressure of the slurry at the inlet and.the pressure of the slurry at the throat is maintained at a ratio with reference to the parameters affecting fluid flow through the nozzle passageway, to ensure that he pressure required to supply slurry to the slurry inlet 7 is independent of the pressure existing in the bowl 24, i.e. the characteris- I ~
tics of the distributor accelerator 26 establishes the I ;
pump pressure required to pump the slurry to the slurry inlet 7. In addition, the nozzle passageway 11 is in-clined radially inwardly towards the axis X-X at an angle such that the slurry has the desired rotational I :
velocity upon entering the discharge passageway 13. It is to be realized that the rotational velocity o~ the slurry within the slurry inlet 7 is dependent upon the . .
-18- . , . . .. .
desi.red rotation o~ the bowl 24 since the distributor accelerator 26 is integral with thebowl 24. In view of the slippage occurring withi.n the distributor-accelera-tor 26 the angular velocity of the slurry is subject to being reduced. Accordingly, the passage-way 11, by being inclined towards the shaft 14, increases the angular velocity of the slurry as it traverses passageway 11 to provide the desired angular velocity of ~he sltlrry at the entrance of the discharge passageway-13 and at the entrance of the bowl 24.
The discharge passageway 13 is circumferen-tially continuous and formed by the otlter surface of the shaft 14 and a surface on the upper por-tion of the distribiltor accelerator 26 and provides a through passageway to introduce the slurry into the bowl 24 at a velocity such that there is a minimum of turbulence ~ I
between the slurry entering the bowl 24 and the material already within the bowl 24. Accordingly, the slurry is discharged from the discharge passageway 13 with -an angular velocity as close as feasible to the angular velocity of the material within the bowl 24 and with an axial velocity as close as feasible to the axial velocity of the material in the bowl 24. For such purposes, the flow axis of the discharge passageway 13 of Fig. 3 is a parallel sided passageway extending axially upwardly ~ :
and slightly radially outwardly to discharge at the radial innermost portion of the bowl 24. Since there are certain changes in the pressure and the angular velocity of the slurry within the discharge passageway due to such inclination the design of the nozzle passageway 11 is , .. , ....... .~.
.l ~239c~3 selected with reference t.o such changes. Distributor-accelerator 26 has an upper surface which is a continua-tion of the curvature of the inner surface of the lower disc portion 42 so tha~ the desired separation as set forth in Serial No. 285,048 is obtained. In selecting the desired discharge veIocity from the discharge passageway 13 the portion of the shaft 14 forming one side of passageway is axially dowmwardly -tapered through the axial length of the discharge passageway 13. In 1~ the embodiment of Fig. 3 the various surfaces o~ the distributor-accelerator 25 which are inclined with respect to the axis X-X have apexes which are coincident ~ith the axis X-X. If desired the outer surface of the passageway in which the vanes 9 are located may be provided with an axial taper.
The distributor-accelerator shown in Figs. 3 ~ ~
and 4 are replaceable by providing access through the ~ I
housing 16, which access is not shown to permit the lower disc 22 to be removed from the shaft 14 and there-after by releasing fasteners 5, inserting a new dis-tributor accelerator. -Shaft 14 has one or more ports 28 to provide a - continuous supply of slurry to the inlet 7 to continu-ously maintain the inlet 7 full of slurry. Preferably, a plurality of ports 28 are provided to supply slurry to circumferentially spaced portions of the inlet 7. As more fully set forth in Serial No. 285,048 the slurry is separated wi-thin the bowl 24 with a resultant dis-chargeable product constituent, that is, the higher denisty portion of the separated slurry being centri-I
fugally moved to the outer portion of the bowl 2~.
The dischargeable product portion moves relative to the bowl 24, however, such movement towards the discharge opening of the bowl 2~ with the dischargeable portion having, as a general proposition a rotational velocity substantially the same as or slightly less than the Z
rotational velocity of the bowl 2~ and little axial velocity within bowl 2~. The effluent constituent, that is, the lower density portion of the separated slurry, has a high ~ater content relative to the product portion and is discharge~ from the bowl 2~
through ports 32. Thus, the slurry in the separation zone of the bowl 2~ must have an axial velocity to main-tain the discharge and a rotational velocity to maintain the rate of despositing of material in th2 product por-- tion. Inasmuch as the slurry is separated into the product constituent and the effluent constituent within the separating zone the axial and rotational velocities of the slurry in the separation zone are not, as a general proposition, equal to the axial and rotational velocities of the constituents. It is to ~e recognized that there are many factors which effect the velocities of the constituents as are known in the art. In Z
accordance with the present invention for ~nown opera-ting parameters the slurry is introduced into the separa-ting zone with the rotational velocity being as close as feasible to the rotational velocity of the prod-lct const:ituent and with the axial velocity being as close as feasible to the axial velocity required to maintain the desired discharge rate of the effluent. By :
. . ~ -so introducing the slurry with such velocities an improved separation of the slurry is obtained i~ that there is a minimtlm of turbulence created within the separating zone between the incoming slurry and the ::
deposited product constituent so that the inner surface of the product constituent is mot eroded by the incoming slurry to cause the product constituent to be re-entrained into the separating zone.
With the distributor-accelerator 26 being as described and of the ~orm as sho~, the vanes 9rotate at the same angular velocity as the bowl 2~ inasmuch as vanes 9 are integral therewith. Accordingly, vanes 9 :
receive the slurry from the inlet 7 and accelerate the ! ' slurry such that the slurry has a given rotational velocity at the discharge end of the vanes 9 which is not necessarily the angular velocity desired for intro- I `
ducing the slurry into the separation zone of the bowl 24. Since passageway 11 converges towards the axis X-X --;
the rotational velocity of the slurry increases within :~
passageway 11. The resultant rotational velocity o~ ¦ :
the slurry is at a value with relation to any decrease ~I.
in rotationalvelocity within passageway 13 such that the I :
slurry enters separating zone with substantially the same rotational velocity as the deposited material within :~
the bowl 24. Thus vanes 9 increase the hydrostatic pressure within the slurry to a value necessary to pro-vide the required volume flow of slurry to the separating zone through the passageways 11 and 13 at substantially `~
the rotationalvelocity o~ the bowl 2~. The discharge passageway 13 has an axial extent such that the axial I ;
.
- . ~. . . .
~2~ 3 - velocity at discharge is at the value required to obtain the desired rate of ~low through the discharge ports 28.
The axial extent of passageway 13 is of a con~iguration to compensate for any gain or loss of rotational velocity - o the slurry in passageway 11. The width and length of passageway 13 are also selected to obtain the desired axial androtational velocity of the slurry as it is dis- -charged into the separation zone.
In designing a distributor-accelerator 26 the axial and rotational velocities of -the constituen-ts within the bowl 24 determine the value that is desired for the axial and-rotational velocities of the slurry for its intro-duction into the separation zone. Thus, the distributor-accelerator 26 is designed with reference to the operating parameters known or described; however, once the configura-tion of the distributor-accelerator 26 is established the pressure of the slurry as it is introduced into the separating zone is determined by the distributor- I ~
accelerator 26 independently of the actual value of the l ;
axial and rotational velocities of the constituents.
Fig. 4 illus-trates another distributor-accelerator 26' construed in accordance with the principles of this invention which is similar to the distributor-accelerator 26 of Fig. 3 except that the nozzle passageway I ~
11 of Fig. 3 has been eliminated and an intermediate ¦ ~, chamber provided between the accelerator vanes 9 and the discharge passageway 13. With such construction the nozzle portion is replaced by a chamber 17 into which the accelerated slurry is discharged by the vanes 9. A ring portion 15' is provided similar to ring portion 15 except ~-1 ~2341?;~
that the portion thereof above the vanes 9 is eliminated.
The slurry inlet 7 is of the same configuration as - -described; however, the lower ancl outer walls thereof are formed by the cup-shaped portion 43' which is similar to cup-shaped portion 43 previously described except for the structural changes required to form inlet 7. The chamber 17 provides a decreasing pressure head on the slurry therein in the axially up~ard direction above the vanes 9 such that the pressure of the material within the bowl 2~ does not establish the back pressure on the slurry in the inlet 7. Chamber 17 does have a more turbulent slurry flow therein than nozzle portion of Fig. 3 however, such turbulence can be accepted if desired.
though the flow of slurry through dis~ributor-accelerator 26' differs from the flow of slurry through the distributor-accelerator 26 each structure provides the desired axial and rotational velocities to the slurry as described. I ; Although preferred embodiments of this invention have been described in accordance with the Patent Statutes those skilled in the art to which this invention relates will re,alize that various modifications can be made to the structures described without departing from the spirit and scope of the invention. Accordingly, the claims hereto are to be construed in accordance with the knowledge of one skilled in tht art to which the inventi~n relates.
-2~-. .
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A centrifuge comprising: an elongated upstanding shaft rotatable about the longitudinal central axis thereof;
a bowl member having upper and lower formed portions secured to axially spaced portions of said shaft, respectively, for conjoint rotation therewith; said bowl member forming a chamber for centrifugally separating a slurry into a product constituent in a radially, with respect to said axis, outer portion of said bowl member and an effluent constituent at a portion of said bowl member radially inward of said product constituent;
said bowl member having means for discharging such constituents therefrom; said lower formed portion having a lowermost section with a formed through passageway therein having, relative to said axis, an axial extent with the axially uppermost end thereof being in open communication with the interior of said bowl member, said shaft having a passageway therein for receiving a slurry and for discharging said slurry to an axially lower portion of said passageway, said lower portion of said passageway having, relative to said axis, a circumferentially and radially outermost extent located radially outward of said uppermost end; and, said passageway having means to control the rotational velocity of a slurry flowing through said passageway.
a bowl member having upper and lower formed portions secured to axially spaced portions of said shaft, respectively, for conjoint rotation therewith; said bowl member forming a chamber for centrifugally separating a slurry into a product constituent in a radially, with respect to said axis, outer portion of said bowl member and an effluent constituent at a portion of said bowl member radially inward of said product constituent;
said bowl member having means for discharging such constituents therefrom; said lower formed portion having a lowermost section with a formed through passageway therein having, relative to said axis, an axial extent with the axially uppermost end thereof being in open communication with the interior of said bowl member, said shaft having a passageway therein for receiving a slurry and for discharging said slurry to an axially lower portion of said passageway, said lower portion of said passageway having, relative to said axis, a circumferentially and radially outermost extent located radially outward of said uppermost end; and, said passageway having means to control the rotational velocity of a slurry flowing through said passageway.
2. A centrifuge as set forth in claim 1 wherein said configuration controls the axial velocity of the slurry intro-duced into said chamber to maintain the rate of discharge of the effluent constituent of said slurry.
3. A centrifuge as set forth in claim 1 wherein said passageway has vanes therein for initially increasing the rotational velocity of a slurry flowing through said passageway and wherein the portion of said passageway at the discharge portion of said vanes is inclined towards said axis and is of a cross section to additionally increase said rotational velocity.
4. A centrifuge as set forth in claim 3 wherein the flow portion of said passageway downstream of said inclined portion is a discharge portion of a uniform cross section communicating with said chamber.
5. A method of controlling the axial and rotational velocity of a slurry continuously supplied to a rotary bowl centrifuge rotatable about an axis wherein the slurry is supplied through an elongated passageway in the bowl and subsequently separated in the bowl into a product con-stituent located within and discharged from a radial outer portion of the bowl and an effluent constituent located radially inwardly of the product constituent and discharged therefrom comprising, initially simultaneously rotationally accelerating and increasing the hydrostatic pressure of an incoming slurry with such a passageway, immediately after such initial accelerating further increasing the rotational velocity of such a slurry with such passageway by having such slurry flow towards said axis, and immediately after such further rotational acceleration discharging such a slurry from such passageway into the interior of such a rotary bowl at a rotational velocity substantially equal to rotational velocity of such a product constituent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA375,998A CA1123403A (en) | 1977-03-03 | 1981-04-22 | Centrifuge apparatus |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77399177A | 1977-03-03 | 1977-03-03 | |
| US773,991 | 1977-03-03 | ||
| CA296,350A CA1103220A (en) | 1977-03-03 | 1978-02-06 | Centrifuge apparatus |
| CA375,998A CA1123403A (en) | 1977-03-03 | 1981-04-22 | Centrifuge apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1123403A true CA1123403A (en) | 1982-05-11 |
Family
ID=27165491
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA375,998A Expired CA1123403A (en) | 1977-03-03 | 1981-04-22 | Centrifuge apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1123403A (en) |
-
1981
- 1981-04-22 CA CA375,998A patent/CA1123403A/en not_active Expired
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |