US3321131A - Centrifuge - Google Patents

Description

H. F. cooK CENTRIFUGE May 23, 1967 6 Sheets-Sheet 1 Filed 001:. 21. 1964 H. F. COOK CENTRIFUGE May 23, 1967 6 Sheets-Sheet 2 Filed Oct. 21. 1964 H. F. COCK OENTRIFUGE May 23, 1967 6 Sheets-Sheet 5 Filed 001:. 21 1964 H. F. COOK May 23, 1967 CENTRI FUGE 6 Sheets-Sheet 4 Filed Oct. 21. 1964 Filed Oct. 21, 1964 May 23, 1967 H. F. cooK 3,321,131

CENTRIFUGE 6 Sheets-Sheet 5 H. F. COOK CENTRIFUGE May 23, 1967 6 Sheets-Sheet 6 Filed Oct. 2],, 1964 United States Patent 3,321,131 CENTRIFUGE Horace F. Cook, Foxboro, Mass, assignor to Bird Machine Company, South Walpole, Mass, a corporation of Massachusetts Filed Oct. 21, 1964, Ser. No. 405,406 10 Claims. (Cl. 233-7) This invention relates to centrifugal separators, and more particularly to such separators of the solid bowl variety in which an adjustable liquid removal conduit is employed to control the level of retained liquid in the bowl.

One object of the invention is to provide such a centrifuge with means, in the form of at least one skimming conduit, for controlling the level of retained liquid over i a range of depths sufficiently wide so that the bowl can be skimmed completely dry before the separator is turned off.

Other objects are to provide a solid bowl centrifuge with dynamically adjustable skimming conduits of a novel construction having the advantages of simple, convenient and reliable operation and servicing, as Well as low cost.

A further object is to provide a skimmer arrangement in such a centrifuge whereby the skimming is done in a gutter adjacent an end of the bowl, and secondary scoops are provided outside the gutter for recirculating liquid that splashes out of the gutter.

Other objects and advantages of the invention will become apparent upon the detailed description below of its preferred embodiments, including the drawings, in which:

FIG. 1 is a vertical axial section of a separator having an effluent conduit according to one embodiment of the invention;

FIG. 2 is an end section taken along line 2-2 of FIG. 1;

FIG. 3 is a horizontal axial section taken along line 3-3 of FIG. 2;

.FIG. 4 is a vertical axial section of the liquid effluent end of the separator, taken along line 4--4 of FIG. 2 showing in dotted lines an alternate position of the skimming conduit;

FIG. 5 is an end section taken along line 55 of FIG. 3;

FIG. 6 is a perspective view of the skimming conduit of the separator of FIG. 1;

FIG. 7 is a section through one part of the skimmer adjustment mechanism, taken along line 7-7 of FIG. 5;

FIG. 8 is a section through another part of the skimmer adjustment mechanism taken along line 8-8 of FIG. 5;

FIG. 9 is an end section of a second embodiment of the invention, similar to the view of FIG. 2;

FIG. 10 is a horizontal axial section taken along line 10-40 of FIG. 9;

FIG. 11 is a vertical axial section taken along line 11-11 of FIG. 9;

FIG. 12 is a perspective view of the skimming conduit of the second embodiment;

FIG. 13 is a vertical axial section of the liquid effluent end of a separator showing the splash recirculation feature of the invention; and

FIG. 14 is an end section taken along line 14-14 of FIG. 13.

Referring to the drawings in detail, one embodiment I of the invention, in which the level of retained liquid Mounted for rotation within the casing 20 is a generally cylindrical bowl 24, terminating at its right hand end as seen in FIG. 1 in a slightly conical end portion 26 and supported at that end by spider 27 and hollow shaft 28 journaled in a suitable bearing assembly 30.

Bowl 24 is provided at its left hand end with effluent bowl head 35 and annular gutter 39. Gutter 39 communicates with the interior of the bowl through openings 36 in head 35, and the diameter of the gutter is slightly greater than that of the bowl, so that all of the liquid reaching the left end of the bowl will pass into the gutter. Bowl 24 is supported at its left hand end by sleeve shaft 37, suitably journaled and driven from outside the casing 20 Mounted coaxially within bowl 24 is a helical conveyor 40 which includes a hollow cylindrical conveyor hub 42 secured at its left hand end to drive trunnion 48 journaled in sleeve shaft 37, and supported at its right hand end by bushing flange 46 and extension hub 44, hub 44 journaled in bushing flange 46 at one end and connected to shaft 28 at the other end. Shaft 37 and trunnion 48 are supported in bearings (not shown) outside the casing and are driven by means (not shown) well known in the art at high but slightly different speeds, e.g. 650 rpm. for the bowl and 630* rpm. for the conveyer.

Extending coaxially within shaft 28 and into conveyer hub 42, clearing the inner surfaces of shaft 28 and flange 46, is fixed feed pipe 50, supported from outside casing 219 in cantilevered fashion by pedestal 52.

The manner in which the liquid removal conduit is mounted will now be described. Casing 20 is constructed of separate top and bottom portions 20a and 20b, which meet along horizontal flanges 59 and 60 to fully enclose the separator. The left end of the casing is provided with an outwardly recessed portion 62 which surrounds shaft 37 as the shaft protrudes out of the casing through circular opening 63. In FIG. 2 the casing is shown with its top removed. It will be noted that flange 60 lies in a common horizontal plane with the axis of rotation of the bowl and conveyer. Extending horizontally from both sides of portion 62, perpendicular to the machines axis of rotation, are pipe sections 65 and 67. These pipe sections lie below shaft 37 and have their common axis in the plane of end wall 61. The outer end of pipe section 65 is closed at 69 and has a downwardly extending outlet 71 for the liquid effluent.

Liquid removal conduit 72 (see FIG. 6) consists of a hollow cylindrical portion 73 and a skimming portion 75 of rectangular cross section, which branches rearwardly out of cylindrical portion 73 near its right hand end, extends first parallel to portion 73 and then turns upwardly. Because of this configuration, when the left end of portion 73 is slidingly disposed in pipe section 65, skimmer 75 extends in towards the machine, and bends around shaft 37 so that skimmer opening 77 is located inside gutter 39 when the conduit is slid far enough to the right (FIGS. 2, 3 5). Skimmer opening 77 lies in the horizontal plane including the machine axis, and the skimmer provides narrow- edged blade portions 78 and 79 which are adapted to be moved, by sliding the conduit in pipe section 65, adjacent the cylindrical wall 41 of gutter 39, so that all liquid entering the gutter will be removed. On the other hand, by sliding the conduit to the left in pipe section 65 the skimmer blade is moved away from the gutter wall and will leave a layer of liquid in the gutter. The left end of cylindrical portion 73 terminates short of and empties into outlet 71. O-ring 76 seals between portion 73 and pipe section 65.

In order to control the position of conduit 72 an extension shaft 89 is bolted to the right hand end of cylindrical portion 73. As best shown in FIGS. 3 and 5, the end of portion 73 to the right of its connection with skimmer 75 comprises a solid portion 74, of roughly triangular cross section. Shaft Stl has an interior recess 81, and bolt 83 passes through the floor of recess 81 into solid portion 74. Shaft 80 is of generally cylindrical cross section and, except as mentioned below, forms a continuous straight extension of cylinder 73 adapted to fit slidingly into pipe section 67. Mounted on the free end of shaft 80 is cap 85, through which adjusting screw 87 is threaded, said screw protruding into recess 81. The other end of screw 87 extends through end cap 89 covering pipe section 67, terminating at adjusting handle 90. Fixed on screw 87 on opposite sides of end cap 89 are set screw collars 92 and 93, which act to prevent translational movement of screw 87 Split clamp 95 is in turn mounted on collar 93, and bolted at 96 to cap 89. Clamp 95 is provided with clamp screw 98, bearing handle 99, so that the clamp may be tightened or loosened to respectively restrain or permit the rotation of adjusting screw 87. Indicating scale 100 is mounted at one end on clamp 95, and extends parallel to screw 87. Indicating scale 1% is mounted at one end on clamp 95, and extends parallel to screw 87. Indicating nut 101 is threaded on screw 87, but slotted to ride along scale 180, so that nut 101 will slide relative to the scale as screw 87 is rotated.

As shown in FIGS. and 7, shaft 80 has a slot 104 running along its top, parallel to the axis of the shaft. Key 186 is bolted at 109 in slot 104, and extends into corresponding slot 168 in conduit 72. Key 106 serves first to further prevent relative rotation of conduit '72 and shaft 80, and second to provide a stop surface 167 in slot 104. At the right hand end of the slot, cap 85 provides another stop surface 110. Directly above slot 104, 'extending upwardly along casing end wall 61, is a verti- "cal sleeve 112, in which is housed a locating pin 114. Pin .114 has at its bottom projections 115, 115, which fit into slot 104. These projections serve to prevent rotation of shaft 80, as well as to limit, in conjunction with stop surfaces 107 and 110, the translational movement of shaft 80. Tapped hole 117 in pin 114 is provided for attaching a tool, so that the pin may be lifted to remove projections 115, 115 from slot 104. To prevent complete removal of the pin from its housing, screw 118 extends through the wall of sleeve 112 into a slot 119 in the pin.

In operation of the device, a slurry of liquid and solid particles is introduced through feed pipe 56 and passes into the spinning bowl 24 through apertures 31 in hub 42. Under the influence of centrifugal force the feed forms a layer against the inner wall of the bowl, the solid particles being urged by reason of their high specific gravity to form a layer immediately next to the face of the bowl while the lighter liquid tends to rise toward the center of the bowl. The solids are then urged to the right, along conical portion 26 and eventually leave the bowl by crossing solids weir 34 and passing through spider 27 into solids discharge chamber 23. The liquid tends to flow in the opposite direction into gutter 39, where it is skimmed away by skimmer 75. The radial depth of the layer of liquid retained in the bowl and in the gutter will remain constant so long as the radial position of skimmer blades 7 8, 79 remains constant and so long as the skimmer has suflicient capacity to remove liquid at the rate it is introduced.

The depth of the retained liquid can be changed while the machine is running by simply loosening clamp screw 98 and rotating adjusting screw 87. The scale 108 and indicating nut 181 will show depth of said layer. The sharp blades 78, 79 permit extremely precise control of the depth, which depth can materially afiect the separating characteristics of the centrifuge. As mentioned, the gutter and bowl can be skimmed dry by moving the skimmer to its extreme right hand position. Thus, wash water can be introduced through the feed pipe after solids have been removed from a slurry, the bowl washed out, and then skimmed dry before the machine is shut down.

FIG. 4 illustrates another feature of the apparatus,

whereby the skimmer can be tilted out of the way of the separator proper, to enable the separator to be lifted out of the casing. To accomplish this, the skimmer is adjusted to its radially inwardmost position, and, after the top 20a of the casing is removed, pin 114 is lifted to permit rotation of shaft 80. Then, the entire conduit assembly is rotated toward the end of the casing.

The embodiment of FIGS. 9l2 employs an alternate technique for mounting the liquid removal conduit, in which the radial position of the skimmer blades are adjusted by pivotally moving the conduit in a plane perpendicular to the axis of the bowl.

In this embodiment, recessed portion 62 and pipe sections 65 and 67 are eliminated from the casing, and in stead the bottom portion 156 of the casing is boxlike in shape and is provided with an internal partition 152 running parallel to the lower left (of FIG. 9) of end wall 61a. Axially aligned openings 154 and 156 are cut in end wall 61a and partition 152, for receiving the conduit.

Conduit 169 comprises a hollow cylindrical portion 161 and a skimmer portion 162 of oblong cross section. Skimmer 162 extends first vertically upward perpendicular to the axis of portion 161, then bends around parallel to said axis, and finally extends in a generally horizontal arc (see FIG. 12), terminating in skimmer opening 163, with skimming blades 164 and 165. Skimmer 162 and cylinder 161 communicate wtih each other to provide a fluid passage. A short shaft portion 167 extends in axial alignment with cylinder 161, bolted to the skimmer at 168 and 169, shaft 167 and cylinder 161 being on opposite sides of the skimmer 162. Thus, the conduit fits between end wall 61a and partition 152, with shaft 167 extending through opening 154 and cylinder 161 extending through opening 156, supporting the conduit for pivotal movement parallel to the plane of end wall 61a. By virtue of its configuration, the skimmer bends into the gutter, and around shaft 37 so that the skimmer Opening is located inside the gutter. ing the conduit the position of the blades 164 and will be changed, thus controlling the retained liquid depth as in the embodiment of FIGS. l-8. It will be noted, however, that in the former embodiment the skimming angle is constant, whereas that angle changes in the present embodiment as the depth is adjusted.

Considering the mounting of the conduit in the casing in more detail, shaft 167 is actually journaled in a fixed cylindrical block 170 as it passes through opening 154,

with skimmer 162 fitting tightly against the internal shoulder 171 of the block. Shaft 167 extends outwardly to overhang external shoulder 172 of the block, and a lever 175 is mounted on the overhang, in contact with shoulder 172, by means of set screw 176.

The upper end of lever 175 provides a pointer 180, which cooperates with scale 181 on the casing wall to indicate the skimming depth. Just below the pointer lever 175 is slotted and fitted with a pivotal screw pin 183. Adjusting screw 185 is threaded in pin 183 and runs hori- Zontally parallel to end wall 61a, terminating at handle 187. The handle end of the adjusting screw passes through split clamp portion 189 of block 188 mounted on the side of the casing. Collars 190 and 191 on either side of the clamp 189 prevent translational movement of the screw 185, while permitting it to be rotated to adjust the position of lever 175, and hence, of the skimmer opening. Clamping handle 192 looks the adjusting screw once the desired skimming depth has been set.

The open end of conduit cylindrical portion 161 terminates within the casing, and has journaled within it a stationary effluent pipe 195, which passes out of the casing. Thus, the conduit 160 can be pivoted without moving the external effluent piping. O-ring 196 seals between cylinder 161 and pipe 195.

FIGURES 13 and 14 illustrate the splash recirculation feature of the invention, applicable to any type of gutter skimming centrifuge in which liquid is subject to splash- By pivot-' ing from the gutter into the casing. Splash pan 2641 is provided below the gutter, in contact with casing end wall 292, said pan having a valley 2201 running parallel to the casing end wall. Recirculation scoops 205, 206, are located on the outer surface of rotating ibowl 24a to pass through valley 201 as the bowl rotates. As liquid splashing out of the gutter collects in valley 201, it is forced into the recirculation scoops as they rapidly and forcefully pass through the collected liquid. The scooped up liquid then returns to the gutter through passages 208, 209 in effluent bowl head 35a.

While the preferred embodiments of the invention have been described in detail, variations within the scope and spirit of the invention will occur to those skilled in the art.

What is claimed is:

1. A centrifugal separator comprising a rotatable bowl for receiving a mixture of liquid and finely divided solid particles,

21 solids discharge chamber adjacent one end of the bowl in communication with the interior thereof through a solids discharge opening,

inlet means communicating with said bowl for introducing said mixture into said bowl,

a rotatable conveyor mounted within the bowl coaxially therewith,

means coupled to said bowl and conveyer for rotating the bowl and conveyer at different speeds to cause the solid particles to move along the inner face of the bowl to the solids discharge chamber, while a layer of liquid is retained in the bowl radially adjacent and in contact with the moving solids,

at least one liquid discharge conduit having a skimming opening,

and means coupled to said discharge conduit and opera-ble while the separator is running for adjusting said skimming opening through a range of radial positions including a position radially inwardly of the bowl wall and a position sufficiently far from the axis of rotation of said bowl to skim dry the entirety of said bowl while said separator is running, said bowl being so shaped and said conduit being so located along the axial extent thereof, that said conduit is adapted to so skim dry said bowl When said conduit is in said last mentioned position.

2. The separator of claim 1 further comprising an effluent gutter located adjacent one end of said bowl, said gutter having a diameter at least as great as the maximum diameter of said bowl, said bowl shaped so that its diameter at every point along its axis of rotation is at least as great as the diameter at every point along said axis farther away from said gutter than said first mentioned point, said separator thereby adapted to discharge liquid into said gutter from all points along the inner surface of said bowl, said skimmer opening located to remove liquid from said gutter, said conduit thereby adapted to skim dry the entirety of said bowl while said separator is running.

3. The separator of claim 2 wherein said means for adjusting the radial position of said skimming opening comprise means operable from outside the separator for moving said conduit parallel to a diameter of said bowl.

4. The separator of claim 2 wherein said means for adjusting the radial position of said skimming opening comprise means operable from outside the separator for pivotally moving said conduit in a plane perpendicular to the axis of rotation of said bowl.

5. The separator of claim 3 wherein conduit guide means are fixed to said separator and said conduit is adapted to slide along said guide means, said guide means including a pipe section to which an effluent pipe is attached, said conduit thereby adapted to move relative to said bowl while said efiluent pipe remains fixed.

6. The separator of claim 4 wherein an efiluent pipe is fixed to said separator and one end of said conduit is mounted in sealed rotatable relation to said pipe, said conduit thereby adapted to undergo said pivotal movement while said effluent pipe remains fixed.

7, The separator of claim 1 further including external means for indicating the radial position of said skimming opening relative to said bowl.

8. The separator of claim 2, further comprising a splash pan located below said gutter and adapted to collect liquid splashing out of said gutter, at least one recirculation scoop mounted on the outside of said rotatable bowl and adapted to pass across said splash pan to scoop up said collected liquid, and a passage leading from said recirculation scoop into said gutter to return said scooped up liquid to said gutter.

9. The separator of claim 1 wherein said conduit comprises at least one narrow edged skimming blade located adjacent said skimming opening.

10. A centrifugal separator comprising a rotatable bowl for receiving a mixture of liquid and finely divided solid particles,

a solids discharge chamber adjacent: one end of the bowl in communication with the interior thereof through a solids discharge opening,

inlet means for introducing said mixture into said bowl,

a rotatable conveyor mounted within the bowl coaxially therewith,

means for rotating the bowl and conveyor at different speeds to cause the solid particles to move along the inner face of the bowl to the solids discharge chamber, while a layer of liquid is retained in the bowl radially adjacent and in contact with the moving solids,

an efiiuent gutter located adjacent one end of said bowl, said separator adapted to discharge liquid into said gutter,

at least one liquid discharge conduit having a skimming opening located in said gutter and adapted to remove liquid from said gutter,

a splash pan located below said gutter and adapted to collect liquid splashing out of said gutter,

at least one recirculation scoop mounted on the outside of said rotatable bowl and adapted to pass over said splash pan to scoop up said collected liquid,

and a passage leading from said recirculation scoop into said gutter to return said scooped up liquid to said gutter.

References Cited by the Examiner UNITED STATES PATENTS 687,374 11/1901 Hamer 68-152 884,830 4/ 1908 Lindahl. 2,125,453 8/1938 Lindgren 233-22 2,154,134 4/ 1939 Millar. 3,172,851 3/1965 Ambler 233-7 3,187,997 6/1965 Gooc'h 233-7 M. CARY NELSON, Primary Examiner, HENRY T. KLINKSIEK, Examiner,

Claims (1)

1. A CENTRIFUGAL SEPARATOR COMPRISING A ROTATABLE BOWL FOR RECEIVING A MIXTURE OF LIQUID AND FINELY DIVIDED SOLID PARTICLES, A SOLIDS DISCHARGE CHAMBER ADJACENT ONE END OF THE BOWL IN COMMUNICATION WITH THE INTERIOR THEREOF THROUGH A SOLIDS DISCHARGE OPENING, INLET MEANS COMMUNICATING WITH SAID BOWL FOR INTRODUCING SAID MIXTURE INTO SAID BOWL, A ROTATABLE CONVEYOR MOUNTED WITHIN THE BOWL COAXIALLY THEREWITH, MEANS COUPLED TO SAID BOWL AND CONVEYOR FOR ROTATING THE BOWL AND CONVEYER AT DIFFERENT SPEEDS TO CAUSE THE SOLID PARTICLES TO MOVE ALONG THE INNER FACE OF THE BOWL TO THE SOLIDS DISCHARGE CHAMBER, WHILE A LAYER OF LIQUID IS RETAINED IN THE BOWL RADIALLY ADJACENT AND IN CONTACT WITH THE MOVING SOLIDS, AT LEAST ONE LIQUID DISCHARGE CONDUIT HAVING A SKIMMING OPENING, AND MEANS COUPLED TO SAID DISCHARGE CONDUIT AND OPERABLE WHILE THE SEPARATOR IS RUNNING FOR ADJUSTING SAID SKIMMING OPENING THROUGH A RANGE OF RADIAL POSITIONS INCLUDING A POSITION RADIALLY INWARDLY OF THE BOWL WALL AND A POSITION SUFFICIENTLY FAR FROM THE AXIS OF ROTATION OF SAID BOWL TO SKIM DRY THE ENTIRETY OF SAID BOWL WHILE SAID SEPARATOR IS RUNNING, SAID BOWL BEING SO SHAPED AND SAID CONDUIT BEING SO LOCATED ALONG THE AXIAL EXTENT THEREOF, THAT SAID CONDUIT IS ADAPTED TO SO SKIM DRY SAID BOWL WHEN SAID CONDUIT IS IN SAID LAST MENTIONED POSITION.

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