US2271493A - Centrifugal separator - Google Patents

Description

Jan. 27, 1942. N. BREWER CENTRIFUGAL SEPARATOR Filed Oct. 21, 1937 7 Sheets-Sheet 3 INVENTOR. NATHANIELBREWER.

MM 6144M ATTORNEY.

Jan. 27, 1942. N. BREWER I CENTRIFUGAL SEPARATOR '7 Sheets-Sheet 4 Filed Oct. 21, 1937 INVENTOR. NATHANIEL BREWER.

ATTORNEY.

Jan. 27, 1942. N. BREWER CENTRIFUGAL SEPARATOR Filed Oct. 21, 1957 7 Sheetsf-Sheet s INVENTOR. NATHANIEL BREWER.

BYW aw A TTORNEY.

Jan. 27, 1942. N. BREWER CENTRIFUGAL SEPARATOR Filed Oct. 21, 1937 '7 Sheets-Sheet 6 INVENTOR. NATHANIEL BREWER.

W. 4. Wm.

ATTORNEY.

Jan. 27, 1942.

Plfli? N. BREWER CENTRIFUGAL SEPARATOR Filed Oct. 21, 1937 7 Sheets-Sheet 7 NATHANIELBREWER.

INVENTOR.

ATTORNEY.

Patented Jan. 27, 1942 CENTRIFUGAL SEPARATOR Nathaniel Brewer, Lansdowne, Pa., assignor to The Sharples Corporation, Philadelphia, Pa., a

corporation of Delaware Application October 21, 1937, Serial No.'170,246

23 Claims.

This invention relates to the separation of liquid from solids, and more particularly to operations involving the application of centrifugal force to materials such as slurries, for separating the mother liquor and particles, such as crystals, which may be small and finely divided.

Rapid and eifective centrifugal separation of liquid from solids may be attained at high rotative speeds, but as the rotor for efiecting such a separation is also subjected to centrifugal forces, machines require materials and design adapted to withstand high stresses created during the operation, with the result that the cost of equipment usually imposes a limitation on its size and the rotative speed for which the machine is designed. An important object of this invention is to provide a machine having an exceptionally high throughput capacity for its size.

This invention provides a complete centrifugal machine, which may operate continuously through definite cycles comprising loading and centrifugally separating liquid from solids, rinsing and drying the separated solids, and unloading the separated solids, preferably by starting the unloading operation to remove dried solids while drying progresses in the remaining solids. Important features of the invention reside in the ability of the machine to perform each of the above steps rapidly and to proceed immediately with the next step as soon as a particular step has been definitely completed. Thus the charge is delivered to the machine through a charge control valve which remains open throughout the loading period and closes practically instantanecusly at the termination of this period. While the machine is loading it is also separating liquid from solids and walling up the latter to form a wall of progressively increasing thickness in the rotor, and concurrently with these operations, liquid is being separated and discharged from the machine. When the wall of fill-mass in the rotor attains a pre-determined thickness the charge .control valve closes, and at this time the separation of liquid from the solids of the supplied charge has been practically completed. The solids are then rinsed and dried and a dislodging tool or scraper is advanced into the wall of fill-mass to cut away the solids, which are removed from the rotor as they are dislodged by the scraper.

A feature of the invention which makes it possible for the machine to receive the charge at an unusually high rate is that the rotor is equipped with a novel filter means, preferably in the form of a single woven screen which does not have the usual lapped seam, but is formed of continuous circumferential strands and axial strands so arranged as to present small apertures to the material to be retained. Larger, selfclearing apertures communicate with the small apertures to prevent clogging and also for conducting liquid to the outer surface of the screen, where its novel construction provides depressions or valleys for conducting liquid axially along smooth wall portions of the rotor to circumferential grooves in the latter, from which liquid is collected and discharged from the rotor. This screen, therefore, provides a pervious filter means capable of clearing away liquid at a rate consistent with the high charging rate of the rotor.

Another feature of the screen is that it has continuous circumferential strands and no lapped seam, so the screen may be entirely concentric with the rotor, and it may be made to fit snugly within the rotor under pressure so as not to require other attaching means, such as those frequently employed for sewing the screen to the rotor wall. The self-clearing feature of the screen and its concentricity are important in connection with the unloading operation.

In the usual centrifugal filter screen construction, comprising a plurality of juxtaposed screens of difierent mesh, fine particles, especially crystals, have a tendency to become lodged in the interstices and on and about the strands of the screens and thus to obstruct the flow of liquid. As this action is not uniform'about the circumference of the rotor, it causes crystals to build up on parts of the screen, and to this extent, causes unbalancing of the rotor. When the machine'is unloaded, the scraper is frequently permitted to advance too close to these obstructed portions and, instead of removing these crystals, it merely rubs over the crystals and presses them further into the screen This rubbing of the crystals tends to form a sort of a glaze which it is very diificult, and sometimes impossible, to remove sufliciently to restore the screen to a condition in which its perviousness is fully restored. This is not only a source of annoyance which eventually requires stoppage of the machine, but it is also uneconomical because when this condition becomes evident, it is necessary, in order to avoid further glazing of the crystals, to leave a layer-of solids unremoved adjacent the screen. The screen of this invention overcomes these difliculties and, therefore, it performs important functions in cooperating with charging the rotor at a high rate. By retaining the screen concentric and unobstructed it is possible to advance the scraper to the desired proximity to the screen with assurance that the efliciency of the machine will not be impaired.

Another feature of the invention resides in the improved action resulting from advancing the dislodging tool, or scraper, through the wall of deposited solids right up to the improved filter screen, without the necessity of allowing for irregularities, -such as those present in prior art machines, which heretofore have made it necessary to leave a substantial layer of solids adjacent the surface of the filter screen. The close proximity of the dislodging tool at its inner limit of movement to the rotating screen at high operating speeds,-creates a turbulence which agitates crystals disposed in the interstices of' the screen. This turbulence assists materially in discharging crystals, or other solids, from the apertures in the screen, and thus leaves the screen in good condition to function during the next cycle.

Another feature of the invention is that a spreader is maintained in engagement with the layer of fill-mass in the rotor during the feeding operation with a light, uniform, contact pressure for levelling off the solids during the progressive increase in thickness of said layer and thereby maintaining a balanced condition of said fill-mass within the rotor. Means are also provided for opposing, with adequate force, any excessive movement of the spreader away from said fill-mass, thereby assuring proper contact of the spreader with the fill-mass during the increase in thickness thereof. The movement of the spreader is utilized to actuate means for closing the charge control valve when the fill-mass attains a predetermined thickness.

Another feature of the invention is that the charge is delivered into the rotor through a feed tube having a feed port extending substantially the full axial width of the rotor wall, and equipped with means within the tube for discharging the fill-mass into the rotor in a curtain or sheet, so as to provide proper distribution and to reduce splashing. Means are also provided for preventing dribbling of the charge through the feed tube into the rotor after the charge control valve has been closed, thereby assuring drier solids.

Another feature of the invention is that of using a chute extending through the housing and having its upper end disposed within the rotor to receive solids as they are dislodged by the scraper, thus removing the solids from the machine as fast as they are dislodged from the rotor. In a machine of this kind, operating at high speed, there is a certain amount of splashing of the charge in normal operations, which presents the danger of causing fill-mass to splash into the open upper end of this discharge chute. Also when handling inflammable or toxic substances, an open chute would be undesirable. In order to obviate these disadvantages, means are provided for closing the upper end of the chute to make the machinesubstantially vapor-tight when it is not unloading. This is accomplished by operating means, extending through the housing and within the chute, for withdrawing the scraper to a position in which it closes the upper end of the chute.

Another feature of the invention is that the change control valve is closed automatically after a predetermined time interval, but means are also provided for closing this valve within this time interval in case the layer of fill-mass attains a predetermined thickness before this time interval has elapsed.

Another feature of the invention is that automatic means are provided for controlling the various steps in each cycle of the machine and for continuing the operation through successive cycles.

Other objects, novelfeatures and advantages of this inve tion will be apparent from the follow ing spec cation, and accompanying drawings, wherein:

Fig. 1 is a side elevation of a centrifugal machine embodying the invention;

Fig. 2 is a plan view of the machine shown in Fig. 1;

Fig. 3 is a front elevation of the machine shown in Figs. 1 and 2, with the exterior piping removed;

Fig. 4 is a central vertical section through Fig. 3;

Fig. 5 is a section along the line 5-5 of Fig. 4;

Fig. 6 is a section showing the feed nozzle partly in elevation and partly in section for purposes of illustration;

Fig. '7 is a section on the broken line 1-4 of Fig. 6;

Fig. 8 is a perspective view of the feed nozzle with part of the tube broken away to illustrate the vertical feed passage;

Fig. 9 is a central, vertical section through a special control member shown in Fig. 3;

Fig. 10 is a top plan view of the mechanism shown in Fig. 9 with the upper part of the casing removed;

Fig. 11 is a detail view illustrating the spreader in side elevation;

Fig. 12 is a developed plan view illustrating the screen on an enlarged scale;

Fig. 13 is a view taken substantially in the direction of the arrow in Fig. 12 illustrating the larger or self-clearing openings in the-screen;

Fig. 14 is a detail view illustrating on an enlarged scale, the valleys or depressions which provide moisture passages along the outer side of the screen adjacent the rotor wall;

Fig. 15 is a detail transverse section through the upper end of the discharge chute, showing the dislodging tool or scraper in its lowered position;

Fig. 16 is a view similar to Fig. 15, but showing the dislodging tool or scraper advanced from the upper end of the chute toward the rotor; and

Fig. 17 is a diagrammatic view illustrating the control drum, the wiring and piping connections and devices associated therewith.

While apparatus embodying my invention is subject to various modifications, the following detailed description of the embodiment shown in the drawings will assist in an understanding of the invention and additional features will appear therefrom.

The illustrated machine comprises a frame l0, equipped with spaced bearings l I and I! in which a shaft I3 is rotatably mounted. This shaft may be driven in any suitable manner, as by means of a pulley I l. A centrifugal rotor I6 (Fig. 4)

comprises a wall II, which may be cylindrical as shown, a ring l8 extending inwardly from one end of said wall and providing an opening [9, and an end wall 2| which is fixedly mounted upon the shaft l3, as by being keyed thereto between a collar 22 on the shaft and a clamping nut 23. A housing 24, which encloses the rotor, is mounted upon the frame I!) and comprises an inner surface with a suitable number of. axially spaced and preferably continuous, circumferential grooves 3| for collecting liquid separated from solids in the rotor. Liquid passes from each of these grooves through radial holes 32 which are circumferentially spaced along the base of each groove and extend through the rotor to its outer surface where the liquid is discharged into the housing. The portions 33 ,of the inner surface of the wall I! of the rotor, which lie between and along these circumferential grooves are continuous, smooth surfaces free from depressions and other irregularities.

' The rotor is equipped with improved filter means in the form of a single ply, woven screen 35 (Figs. 4, 5, 12, 13, and 14) which is fitted under pressure snugly against the inner surface of the wall I! and comprises closely spaced, continuous, circumferential strands 36 (Fig. 12) and widely spaced, axially extending strands 31. Preferably the widely spaced axially extending strands 31 are formed to curve about the continuous circumferential strands 36, as shown in Figs. .13 and 14. If desired, the circumferential strands may be somewhat smaller in diameter than the axial strands, but this isnot necessary as very good results are obtained when the strands are all of substantially thesame diameter as shown. The continuity of the circumferential strands makes the usual lapped seams unnecessary, thus contributing to more perfect balance of the machine. This filter means may be made conveniently by forming a piece of this woven screen into the desired cylindrical, or other shape, and welding adjacent ends of strands 36 to form a screen which will fit snugly against the inner wall of the rotor, so that it may be pressed into the rotor and will remain in place due to its own resilience. This construction does away with the need for the usual attaching means for sewing the screen in place.

As shown in Fig. 12, the closely spaced, circumferential strands 36 cooperate with the widely spaced, axial strands 31 to form a pervious filter having small apertures in the form of narrow slits 38 disposed about the circumference of the rotor for passing liquid while intercepting and retaining solid particles. Viewing the inner surface of the screen at an angle to its surface as indicated by the direction of the arrow in Fig. 12, it will be seen that the narrow slits 38 diverge somewhat axially and outwardly of the The peculiar woven construction of this screen provides depressions, or valleys 4| (Fig. 14) ex- This housing is provided with an outlet 29 tending axially of the rotor along the outer surface of the screen. Each of these valleys has its greatest depth at points midway between adjacent axial strands 31. These valleys cooperate with the adjacent smooth portions of the inner suikface of the rotor to provide a great number of well defined passages for conducting liquid from the screen axially along the rotor wall to the grooves 3|.

While the liquid receiving or collecting grooves 3| have been illustrated as continuous circumferential grooves disposed in parallel planes, and

the valleys 4| have been shown as extending axially, it will be evident that this relationshipf may be varied widely so long as the valleys lead to or traverse the grooves. In general this result-may be attained by making the grooves 3| and the circumferential strands 36 extend in approximately the same direction, as in approximately parallel planes.

A single ply screen of this woven construction is entirely adequate and satisfactory as a filter means. It remains concentric within the rotor and is capable of passing liquid at a consistently high rate. This makes it possible to deliver the charge to the rotor at an exceptionally high, substantially uniform rate, and also in unloading, to advance the dislodging tool or scraper very close to the screen with reasonable assurance that this tool will not encounter solid particles, such as crystals, which have become wedged between strands of the screen, and, as a result,

rubbing and glazing of such crystals is avoided.

The means for feeding the charge, such as a slurry, to the rotor, comprises a feeding conduit 42 (Figs. 1 and 2) which may be supplied with slurry in any suitable manner, as by means of a hopper (not shown). A pneumatically operated charge control valve 43 is provided in the feeding conduit 42, preferably adjacent the rotor housing 24. Preferably, the feeding conduit 42 extends only to the end plate, or closure member 28 of the housing, and a feed tube or nozzle 44 (Figs. 6, 7, and 8), extends axially into the rotor from the closure member 28.

The feed tube 44 preferably has approximately the sametransverse cross-sectional area as that of the outside piping and has its inner end closed. This tube is provided along its under side with a slot 46, preferably having substantially thesame area as the transvqse cross-section of the tube and feed pipe. This tube extends in an axial direction across the rotor for substantially the full axial width of wall l1. Within this tube substantially parallel walls 41 and 48' extend upwardly along the sides of the slot, and transverse parallel walls 49 and 5| extend upwardly from the ends of the slot to form a standpipe. The charge material, delivered to the feed tube, passes over the upper ends of these parallel walls into the passage provided by the standpipe, and issues from the slot 46 into the rotor (Fig. 5) at high velocity, in a smooth, continuous curtain or sheet of substantially uniform thickness. This mode of feeding reduces splashing to a minimum, and assures uniform feed of the charge across substantially the full axial width of the rotor. When the charge control valve closes, charg material in the feeding conduit between this valve and the feed slot 46 would ordinarily continue to dribble through the slot 46 into the rotor, where it would come in contact with partially dried solids. In order to prevent this dribble, a drain hole (Figs. 6 and '7) is provided in the feed nozzle 44 at a point between the ring l8 of the rotor and the end plate 28 of the rotor housing, and below thelevel of the top of the standpipe. With this arrangement, when the charge control valve closes, the feeding of the charge into the rotor stops abruptly as soon as the level of charge material in the feed nozzle falls below the level of the top of the standpipe, and the charge material which is left in the feed tube below the level of the standpipe drains through hole 45 into the rotor housing, where it is carried away with other liquid through the outlet 29. This arrangement proyides drier solids in the rotor.

Rinse liquid is delivered through a conduit 52 (Figs. 1, 2 and 3) through the end plate or closure member 28 and is discharged into the rotor by any suitable means, such as the nozzle 53. A solenoid controlled valve 54 (Figs. 1 and 2) is interposed in conduit 52 for controlling the flow of rinse liquid.

A spreader 55 (Figs. 4, 5 and 11) is mounted to extend within the rotor for engagement with solid particles, as the latter accumulate to form a cake of progressively increasing thickness. This spreader or rake engages the accumulating solids or cake with a slowly yielding light contact pressure so as to improve the distribution of solids and to level ofi the cake. As shown in Fig. 11, a

shaft 56 is rotatably mounted in a bearing boss 51 in the end plate or closure member 28 of the housing, and extends axially within the rotor. The spreader proper comprises a boss 58, which flts over the inner shaft 56 and is fixedly attached thereto as by means of set screws 59 and a key 60 (Fig. 5). A suitably reinforced web 58' depends from boss 58, and a plate 6| is attached to the web as by means of bolts 82. The lower part of this plate inclines at an acute angle with respect to the direction of rotation of the adjacent rotor wall, and the lower edge of this plate preferably is serrated to provide a row of teeth 8|, extending across the full axial width of the rotor, for assisting in distributing and in levelling off the solid particles during the formation of the cake.

As the solid particles or crystals accumulate to form a cake of progressively increasing thickness, the spreader rotates slightly in the same direction as the rotor and is maintained in engagement with this accumulating cake, with a substantially uniform and relatively light contact pressure. Snubber means are provided for opposing with adequate force any tendency of the spreader to move away from the rotor wall any further than is necessary to accommodate the increase in thickness of the solids. Fluid pressure means, indicated generally at 83 in Figs. 3, 9 and 10, is provided for accomplishing these results.

This fluid pressure means comprises a housing 64 formed of upper and lower separable sections 85 and 66 respectively. This housing may be attached to the rotor housing, or to any other fixed support, as by means of a bracket 61. The lower portion of housing 64 is in the form of a cylinder 88 in which a piston 69 is mounted. The upper portion of this housing is in the form of a chamber ID in whicha bell crank 'II is mounted. This bell crank comprises a horizontal shaft section'12 mounted in bearings 13 and 14 formed in the up- .per and lower sections 65 and 68 of the housing,

and having depending arm 15 (Fig. 3), and a transversely disposed arm 15 (Fig. 9) equipped with a roller 11, which engages an abutment 18 formed on the upper side of piston 69. The upper part of this housing is provided with an overflow port I9, and chamber 19 is adapted to contain pressure fluid, such as oil, up to the level of this port. Preferably, a passage 8| extends through the piston between the lower and upper sides thereof, and a pressure relief valve 82 is mounted in this passage to relieve excessive pressure from the cylinder to the upper side of the piston. Pressure fluid, such as oil, is supplied to the lower end of the cylinder through a check valve 83 (shown only in Fig. 1'7) and a port 84. Pressure fluid is normally discharged from the lower end of the cylinder through a port 85, which is restricted to the desiredextent by means of a needle valve 88. A vertical passage 81 extends between the needle valve and chamber I0.

The means for transmitting motion from the spreader to this fluid pressure means comprises an arm 88 (Fig. 3) fixedly mounted on the outer end of shaft 56, as by means of set screws 89, and a key 90 (Figs. 3 and 11), and a link 9|, which is pivotally connected to the lower end of this arm and to the lower end of depending arm 15 of the bell crank. As the spreader moves away from the rotor wall, or in a counter clockwise direction, as viewed in Fig. 5, to accommodate the progressive increase in thickness of the forming cake, this movement of the spreader is transmitted through arm 88, link 9| and bell crank H to the abutment l8, and moves the piston downwardly. The rate at which this movement may take place is determined by the adjustment of needle valve 86 which restricts the flow of fluid displaced by the piston.

It will be evident that this fluid pressure means may be adjusted by properly setting the needle valve, so as to oppose movement of the spreader with a force which will maintain the spreader in engagement with the accumulating cake, during the increase in thickness thereof, with a light, substantially uniform, contact pressure. If the spreader should engage an accumulation or lump of solids, the impact of such engagement at high speed would practically instantaneously exert an increased pressure on the piston through the linkage just described, but this increase in pressure would be effectively absorbed and opposed by the pressure fluid in the cylinder before the piston could travel sufficiently to permit the spreader to move out of contact with the forming cake. It will be seen, therefore, that during the progressive increase in thickness of the cake of accumulating solids, the spreader moves outwardly to accommodate the normal increase in thickness thereof, and yet maintains a light contact pressure on said cake.

It will be evident that the position of the spreader, and the linkage associated therewith, varies with the thickness of the cake of solids in the rotor. Movement of the spreader, in response to the progressive increase in thickness of the solids, is utilized for actuating means to cause the charge control valve to close. As shown in Fig. 3, a rod 92 is pivotally connected to the lower end of arm 88, and extends through a slot (not shown) in a pivotally mounted valve operating arm 93. The outer end of rod 92 is threaded to receive nuts 94 which may be locked on the rod in any desired position to constitute an adjustable abutment, which is engageable with arm 93 to rock the latter in a counter-clockwise direction, as viewed in Fig. 3. These nuts are positioned to permit rod 92 to move freely through arm 93 until the spreader moves to a position at which the layer of solids in the rotor will have attained the desired thickness. As this movement occurs, the nuts engage arm 93 and swing it in a counterclockwise direction to open a valve I (Fig. 17) hereinafter described, and this causes the charge control valve to close. In order to prevent arm 93 from overswinging in a clockwise direction,

this arm is equipped with an abutment 95, which engages a fixed abutment 95' whenthe parts occupy the positions shown in Fig. 3.

This machine is equipped with a dislodging tool or scraper 96 (Figs. 4, 5, 15 and 16) having a cutting edge 91 engageable with the cake of solids across the full axial width thereof. A chute 98 (Figs. 3, 4, 5, 15 and 16) has its open upper end disposed within the rotor in position to receive solids dislodged from the rotor during the unloading operation. This chute extends outwardly from the rotor through an opening 99 (Fig. 4), which is bounded by a flange IN on end plate 28 of the rotor housing. A flange I02, attached to the chute, overlies flange IN and suitable packing I03 between these flanges completes a vapor-tight seal between the chute and the rotor housing. As other parts of the rotorhousing are effectively sealed at all times, this seal about the chute makes the machine vapor-tight except for the material receiving opening I04 in the upper end of the chute.

In order to make the machine vapor-tight at all times except when solids are being dislodged and discharged through the chute, the opening I04, which constitutes the receiving end of the chute, is made substantially complementary to the outline, or contour, of the dislodging tool or scraper, and means are provided for moving the scraper to a position to close this opening.- As

shown in Fig. 15, the rear or following edge I05 of the scraper fits snugly against the side I06 of the chute opening I04; the end I01 of the scraper fits against the inclined inner portion I08 of the chute (Fig. 4) and the other end I09 of the,

scraper fits against the complementary portion I I0 of the chute. Beneath the cutting edge of the scraper (Figs. and 16) a bent strip of resilient metal III-is attached along the edge of the chute opening for yieldable engagement with the under side of the knife. This completes the means for closing the chute.

Preferably, means extend through the chute for supporting and operating the scraper within the rotor. the scraper operating means in additional openings through the housing. This arrangement renders the scraper operating means accessible at all times, and it also saves space.

As shown in Fig.4, the scraper is mounte upon arms H2 and H3 which are fixedly at- This avoids the necessity of sealing operation of the machine comprise a rotary control drum I (Fig. 17) having its surface represented in developed plan by the rectangle enclosed by lines I3I, I32, I33 and shaft I34. It will be understood that this drum is mounted upon and rotates with the shaft I34. A timer control motor I35 is provided for rotating this drum, and a spiral return spring I36, which is connected to the shaft and to a fixed support I31, opposes rotary movement imparted to the drum by the motor and becomes effective when the motor is cut out to return the drum toits initial position. Suitable speed reducing means, such as the gear train I44, may be interposed between the motor and the drum.

The shaft I34 is slidable axially in its bearings I and I46, to provide for engagement and disengagement of a clutch I41, which connects this shaft to the gear train. A toggle I48 is engageable with one end of the shaft for shifting the latter to effect engagement of the clutch. A

spring I49, connected to this toggle and to a fixed support I 50, acts normally to break the toggle and to allow the shaft to shift to disengage the clutch. A solenoid consisting of a coil I5I and'a core piece I52 is connected to the knee of the toggle. When this solenoid is energized, the coil I5I attracts the core piece I52, and this straightens the toggle and shifts the shaft I34 to effect engagement of clutch I46.

Electrical energy for operating the timer control motor is supplied from the line through a switch I53 to a main circuit comprising a conductor I54 leading from one terminal of switch I53 to limit switch I23, from which a conductor I55 leads to a relatively long contact bar I56 which is mounted upon and movable with the tached to a horizontal shaft II4. This is a nonrotatable shaft, preferably square or rectangular in cross section, which is mounted for longitudinal adjustment in a boss II5 carried by a yoke II6 (Figs. 1, 3 and 4). This yoke is mounted to reciprocate vertically along guide rods II] and H8 (Fig. 3), which are fixedly mounted on end plate 28 of the rotor housing. A single acting fluid pressure cylinder H9 is mounted on end plate 28 above the yoke, and a piston I 20 (Fig. 4) in said cylinder has its rod I 2I secured to the yoke in any suitable manner,-as by means of a threaded connection I22.

The limit of upward travel of the piston I20 is controlled by a limit switch I23 (Fig. 3) which may be mounted upon any fixed support, as upon a bracket I24 carried by the cylinder. A vertically disposed arm I26 attached to the yoke is engageable with the operating arm I21 of the switch. It will be understood that this control of the upward travel of piston II9 determines the extent of the advance of the scraper through the wall of solids or cake in the rotor.

Means for controlling the various steps in the control drum I30. A stationary contact I51 engages contact bar I56 during rotary movement of the drum. A conductor I58 leads from contact I51 to the timer control motor I35, and a conductor I59 leads from this motor to the other terminal of switch I53. The solenoid I5I has one of its terminals connected by the conductor I60 to the conductor I55, while the other terminal of this solenoid is connected by a conductor IGI to conductor I59.

It will be clear that when switch I53 is closed, the circuit just described will be completed through solenoid I5I and through the timer control motor. As this solenoid is energized, it retracts its core piece and thereby straightens the toggle, which shiftsthe shaft I34 to engage clutch I 41. Therefore, the timer control motor drives the shaft I34 through the reduction gearing I44' andthe clutch I41. This imparts rotary movement to the control drum I30 until contact bar I56 rotates beyond contact I51 and opens the circuit, stopping motor I35. The torsional spring I36 then returns the drum to its initial position where it is stopped by engagement of an abutment I62, carried by the drum, with a fixed abutment I63.

The charge control valve 43 is actuated between completely closed and fully open positions by a pneumatic motor I65 (Figs. 1 and 17), comprising a diaphragm I66, which is deflected downwardly in response to pressure in chamber I61, Pressure fluid, such as air, is supplied from a suitable source (not shown) to the chamber I61 through a conduit I68, a three way valve I69 and a conduit I 10.

A chamber I1I below the diaphragm may be open to atmosphere. A rod I12 is connected to the diaphragm and to the valve disc 43' of the charge control valve. An expansible spring I13 seats against a fixed 'abutment I14 and bears against w an abutment "I15 on rod I12. It will be seen that this spring normally holds the valve 43 closed. When air pressure is supplied to chamber I61, the diaphragm and rod I12 move downwardly, compressing spring I13 and opening valve 43.

Time control means for opening the charge control valve and closing the same after a predetermined time interval comprises a circuit leading from conductor I55 through a conductor I16 to a contact bar I11 which is movable with the control drum. This circuit then leads through a stationary contact I18, which is engageable with this contact bar, through a conductor I19 to a solenoid I80, and from this solenoid through a conductor I8I to conductor I59 of the previously described timer motor circuit. When the circuit just described is completed, the solenoid operates the three way air valve I69 to supply air pressure from conduit I68 through conduit I to chamber I61 to open the charge control valve. When this electrical circuit is open, a spring I82, which opposes the action of solenoid I80, operates the three way valve I69 to close conduit I68 and to connect conduit I10 with an exhaust conduit I83. This relieves pressure from chamber I01 and permits the charge control valve to close.

In the normal operation of the machine, the layer of solids accumulating in the rotor will attain the desired thickness before contact bar I11 moves beyond contact I18 to open this circuit. Therefore a conduit I84 is connected to conduit I10 and leads through a valve I85 to an exhaust conduit I86. When the wall of solids in the rotor attains the desired thickness, arm 88 (Fig. 3) is actuated by movement of the spreader, previously described herein, to open valve I85 and this permits pressure fluid to be discharged from chamber I61 so that the charge control valve 43 will be closed by spring I13.

Time control means for operating the rinse control valve 54 (Figs. 1, 2 and 1'1) comprises a circuit leading from conductor I55 through a conductor I81 to a contact bar I88, which is movable with the control drum. From this contact bar the circuit leads through a stationary contact I89, engageable with the bar, through a conductor I90, a solenoid I9I and a conductor I92 to conductors I8I and I59. When the circuit just described is completed, the solenoid is energized to open the rinse control, valve, and when this circuit is open, a spring I93 associated with solenoid I9I acts to close the rinse control valve.

Time control means for feeding the dislodging tool or scraper into the wall of solids, or cake, in the rotor, comprises a. circuit leading from conductor I55 through a conductor I94 to a contact bar I95 movable with the control drum, and thence through a stationary contact I98, which is engageable with this contact bar, through a conductor I91, a solenoid I98 and a conductor I99 to conductors I8I and I59. When this circuit is completed, solenoid I98 closes a normally open valve 200 and thereby directs pressure fluid such as oil, to pressure cylinder II9 to feed the dislodging tool into the cake in the rotor, as will presently be explained. When this electrical circuit is open, solenoid I98 is de-energized and valve 200 is opened by a spring 20I associated with this solenoid.

Means for operating pressure cylinder I I9 comprises a tank or reservoir 202, which may be mounted in the base of the machine (Fig. l), and a fluid impelling means, such as a rotary pump 203, which may be operated (Figs. 1 and 2) from the main shaft I3 through suitable gearing "204, which drives shaft 205 to operate the pump.

Suitable fluid, such as oil, is supplied from tank 202 through a connection 206 to the inlet of the pump. A conduit 201 leads from the discharge of the pump to pressure cylinder H9.

for operating the piston, and a check valve 2I3 is connected in a by-pass 2 I4 around needle valve 2I2. This check valve is arranged to permit a quick return of fluid from cylinder II9. Pressure fluid is also supplied from conduit 201 through a connection 2I5 leading to the check valve 83 and port 84 (Figs. 9, .10,- and 17).

It will be seen that when valve 200 is open, fluid merely circulates from the discharge side of the pump into conduit 201 and through bypass 208 back to the tank. When this by-pass is closed by valve 200, fluid is compelled to flow into cylinder II8 through needle valve 2I2. This causes piston II9 to travel upwardly until limit switch I23 is opened by engagement of arm I26 carried by the yoke, with the actuating arm I21 of this switch. When this occurs, the circuit through the timer control motor is opened, solenoid I98 is de-energized, valve 200 opens permitting fluid to be by-passed to the tank, and fluid is promptly discharged from cylinder II9 through check valve 2 I 3. The weight of the parts carried by the yoke causes the piston to return quickly to the lower end of its stroke. It will be understood that as the piston II9 returns, the dislodging tool or scraper will also descend to close the upper end of the chute as previously described.

In the operation of the machine, power is transmitted to the main shaft I3, as by means of a belt (not shown) trained over pulley I4, and the rotor I6 is set in rotation. As soon as the rotor attains the desired speed, the operator closes the switch I53, thereby completing the circuit through the timer control motor I35, which starts to rotate the control drum I30. The rotation of this drum causes the movable contact bar I11 to engage stationary contact I18 and completes the circuit through solenoid I80, which operates the three-way air valve to admit. air under pressure to chamber I61 to open the charge control valve, and to hold it open until pressure is relieved from chamber I81.

As the layer of solids or cake deposited in the rotor attains the desired thickness, movement of the spreader 55 opens valve I85 to permit air to escape from chamber I61 to exhaust connection I86. As air escapes from chamber I61, the spring I13 closes the charge control valve 43.

It will be clear from the foregoing that as this charge control valve closes, solenoid I may still be energized. This is the usual mode of operation, but ocasionally there may be a condition in which the solids deposited in the rotor do not build up a cake of the desired thickness within the time interval usually allotted for this purpose. A condition of this kind may be due to a particularly viscous slurry, or to some other cause. When this condition is encountered, valve I85 does not open, and the opening ofthe circuit through solenoid I80 functions as a time control means "to de-energize this solenoid and thereby renderits associated spring I82 effec-., I

tive for operating; the three-way valve to close conduit I68 and to connect conduit I with exhaust conduit I83 so that the charge control valve may close as previously described. These operations occur only after the lapse of the time interval, during which contact I18 remains in engagement with contact bar I11 and after this the contact bar I11 and contact I18 separate to open this time control circuit.

As the control drum continues to rotate after contact bar I11 has moved away from contact I18, the next time control means to function is the one governing the operation of the rinse control valve 54. As contact bar I88 engages stationary contact I89, solenoid I9I is energized, and opens the rinse control valve, which remains open during engagement of contact bar I88 and contact I89. As the movable contact bar opens this circuit by separating from contact I89, the solenoid I9I is de-energized, and the rinse control valve is closed by the action of a spring I93 which opposes the action of this solenoid.

The continued rotary movement of the control drum brings the movable contact bar I95 into engagement with the stationary contact I96 to complete the third time control circuit after the lapse of a predetermined interval following the I closing of the rinse control valve, during which interval the solids are dried by the rotation of the rotor. As this third time control circuit is completed, solenoid I98 is energized and closes thenormally open valve 200, causing pressure fluid to be conducted to pressure cylinder 9. As thepiston I20 travels upwardly inthis cylinder, it advances or feeds the dislodging tool, or

scraper, into the cake of solids deposited in the rotor. As this tool advances through the cake, arm I26 mounted on theyoke approaches and finally engages the actuating arm I21 of the limit switch I23 to operate the latter to open the main to drive the drum I32 which determines the time at which the dislodging tool shall begin its advance. The extent of the advance of the dislodging tool is determined by the relative adjust- ,ment of arm .I21 of limit switch I23 and arm I28 carried by the yoke.

The centrifugal machine disclosed. h rein is adapted to operate at high speeds, that is, at speeds capable of developing a centrifugal force "o'f'the order of one thousand times gravity, or greater. It will be appreciated that with a machine developing such a high centrifugal force, the separation and drying of solids takes place very rapidly. The drying of solids is further expedited by the arrangement of the improved single concentric screen in the perforate rotor, which provides for discharging and clearing away separated liquid at a high rate. This-makes it possible to charge the machine at a correspondingly high rate and thus provides for loading in minimum time. The cooperative relationship of the dislodging tool or scraper and the filter screen provides for removal of all but a very thin layer of solids. When the scraper is advanced through the wall of solids into the close proximity to the screen afforded by these features, there is a turbulence created between the rotor and the scraper which draws material from the screen and thereby assists in freeing the apertures thereof so that they will be open and unobstructed for the next loading operation.

Modifications will be obvious to those skilled in the art, and I do not therefore wish to be limited except by the scope of the sub-joined claims.

I claim: I

1. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a wall of progressively increasing thickness, a charge control valve, means tending to close said charge control valve, a fluid pressure motor for opening said charge control valve, admission and exhaust circuit at this switch. This of course de-energizes solenoid I98, breaks the circuit through solenoid I5I, and permits valve 200 to open the by-pass around the pump so that pressure fluid may be discharged from the cylinder .to tank 202 and the dislodging tool may be returned to its position across the top of the chute.

During this interval, while the circuit is open at switch I23, the torsion return spring I36 functions, as previously described herein, to return the control drum to its initial position in which all of the time control circuits except the mainv motor circuit are open at the movable contact bars associated therewith. The limit switch I23 closes as the yoke I I6 descends and the circuit is completed through the timer control motor for operating the control drum-through another cycle in the manner just described. It will be evident that these cycles follow in rapid succession.

It will be noted that contact bar I95 is adapted by its position and length to remain'in engagement with contact I96 after the timer motor circuit has been opened by contact bar I 58 moving away from contact I51. Hence this engagement of contact bar I95 and contact I96 is a continuing engagement after the motor I35 has ceased valve means for said motor, time control means for operating said admission and exhaust valve means in definite timed relation, other exhaust valve means for relieving pressure from said motor, and means responsive to the thickness of the wall of fill-mass for operating said other exhaust valve means. I

2. Ina machine for separating liquid from solids, the.combination of a rotor, means for feeding fill-mass into the rotor to form a wall of progressively increasing thickness, a charge control valve, means tending to close said charge control valve, fluid pressure motor for opening said charge control valve, admission and exhaust valve \means for said motor, electro-mechanical meansfor operating said admission and exhaust valve means, time control means for operating said,electro-mechanical means, other exhaust valve means for relieving pressure from said motor, and means responsive to the thickness of thewall of fill-mass for operating said other exhaust valve means.

3. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotorto form a wall of pro gressively increasing thickness, a movable spreader engageable with the wall of fill-mass during the increase in thickness thereof, means for holding the spreader in relatively light engagement with the wall of fill-mass during .the .increase in thickness thereof, a charge control valve, time control means for opening the charge control valve and for closing said valve after a predetermined time interval, and means operable in response to movement of the spreader as the wall of fill-mass attains the desired thickness for closing the charge control valve.

4. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a wall of progressively increasing thickness, a movable spreader engageable with the wall offill-mass during the increase in thickness thereof, fluid pressure, means for opposing movement of the spreader with a relatively light, substantially uniform pressure substantially throughout the range of movement of the spreader during its engagement with the wall of fill-mass, a charge control valve, time control means for opening the charge control valve and for closing said valve after a predetermined time interval, and means operable in response to movement of the spreader as the wall of fill-mass attains the desired thickness for closing the charge control valve.

5. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a' wall of progressively increasing thickness, a movable spreader engageable with the wall of fill-mass during the increase in thickness thereof, fluid pressure means for opposing movement of the spreader in normal increments in response to increase in thickness of the wall of fill-mass with a relatively light, substantially uniform, contact pressure substantially throughout the range of movement of the spreader during its engagement with the wall of fill-mass, means effective substantlally throughout the range of movement of the spreader for opposing with considerably greater force movement of the spreader in larger increments than required to maintain said light contact pressure on the wall of fill-mass, a charge control valve, time control means for opening the charge control valve and for closing said valve after a predetermined time interval, and means operable in response to movement of the spreader as the wall of fill-mass attains the desired thickness for closing the charge control valve.

6. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a wall of progressively increasing thickness, means for feeding rinse liquid into the rotor, a charge control valve, a rinse control valve, means for opening and closing said charge control valve, electromechanical means for controlling the operation of the latter means, a time control circuit including said electro-mechanical means, relatively movable contacts in said circuit for completing said circuit and for opening the same after a predetermined time interval and thereby causing said charge control valve. to open at the beginning of said time interval and to close at the expiration thereof, independently operable means responsive to the thickness of the wall of flllmass for closing said charge controlvalve within said time interval, electro-mechanical means for operating said rinse control valve, a second time control circuit including the latter electro mechanical means, relatively movable contacts in said second time control circuit, the latter contacts being engageable for a predetermined period after said time interval for operating the electro-mechanical means associated with the rinse control valve to open the latter valve and to close the same at the expiration of said predetermined period.

'7 In a machine for separating liquid from solids, the combination of a rotor, means for feed;

ing fill-mass into the rotor to form a wall of fillmass, a scraper for removing fill-mass from the rotor, means responsive to fluid pressure for feeding the scraper into the wall of fill-mass, a source of pressure fluid, ,electro-mechanical means for directing pressure fluid into said fluid pressure responsive means, a time control circuit including said electro-mechanical means, relatively movable contacts in said circuit for completing said circuit and thereby causing pressure fluid to be directed to said fluid pressure responsive means, means independent of said movable contacts for discontinuing the flow of pressure fluid to said fluid pressure responsive means, and means controlled by the position of said scraper for actuating said last-named means.

8. In a machine for separating liquid from solids, the combination comprising a rotor having a perforate circumferential wall, a resilient woven wire screen of continuous circumferential configuration snugly fitting within said wall, means for feeding to said rotor solids contaminated with liquid to be separated therefrom, a solids dislodging tool, and means for effecting movement of said solids dislodging tool into a position in said rotor in which said dislodging tool lies closely adjacent to said screen, said screen being formed of circumferential strands placed closely together, and of transverse strands woven through said circumferential strands and spaced relatively widely apart, the portions of said circumferential strands between said transverse strands forming, together with the surrounding rotor wall, a plurality of transversely extending passageways, and said circumferentially extending rotor wall being provided in its inner circumference with circumferentially extending channels intersecting said passageways and the perforations in said circumferential wall, whereby liquid draining through the screen under the influence of centrifugal force passes through said transversely extending passageways to said circumferentially extending channels and through said channels to said perforations.

9. In a machine for separating liquid from solids, the combination comprising a rotor having a perforate circumferential wall, a resilient woven wire screen of continuous circumferential configuration snugly fitting within said wall, means for feeding to said rotor solids contaminated with liquid to be separated therefrom, a solids dislodging tool, and means for effecting movement of said solids dislodging tool into a position in said rotor in which said dislodging tool lies closely adjacent to said screen, said screen being formed of circumferential strands placed closely together, and of transverse strands woven through said circumferential strands and spaced relatively widely apart, the portions of said circumferential strands between said transverse strands forming, together with the surrounding rotor wall, a plurality of transversely extending passageways, and said circumferentially extending rotor wall being provided in its inner circumference with circumferentially extending channels intersecting said passageways substantially at right angles and also intersecting the perforations in said circumferential wall, whereby liquid draining through the screen under the influence of centrifugal force ,passes through said transversely extending passageways to said circumferentially extending channels and through said channels to said perforations.

10. In a machine for separating liquid from solids, the combination of a rotor, a spreader movabletoward and from the fill-mass for engagement therewith as the fill-mass accumulates in said rotor, substantially continuously effective means for opposing movement in normal increments of said spreader away from said flllmass with a substantially uniform force substantially throughout the range of movement of said spreader, and substantially continuously effective means for opposing excessive movement of said spreader away from said fill-mass with greater force.

11. In a machine for separating liquid from solids, the combination of a rotor, a spreader movable toward and from the fill-mass for engagement therewith as the fill-mass accumulates in said rotor, substantially continuously efiective means for opposing movement in normal increments of said spreader away from said fill-mass with a substantially uniform force substantially throughout the range of movement of said spreader, and fluid pressure means for opposing excessive movement of said spreader away from said fill-mass.

12. In a machine for separating liquid from solids, the combination of a rotor, a spreader movable toward and from the fill-mass for engagement therewith as the fill-mass accumulates in said rotor, a fluid chamber having a restricted discharge port, and means responsive to movement of said spreader away from the fill-mass for displacing fluid from said chamber through said port.

13. In a machine for separating liquid from solids, the combination of a rotor, a spreader movable toward and from the fill-mass for engagement therewith as the fill-mass accumulates in said rotor, a cylinder adapted to contain a non-compressible fluid, said cylinder having a restricted discharge port, a piston in said cylinder, and means responsive to movement of said spreader away from the fill-'mass for causing said piston to displace fluid from said cylinder through said restricted discharge port.

14. In a machine for separating liquid from solids, the combination of a rotor, a spreader movable toward and from the fill-mass for engagement therewith as the fill-mass accumulates in said rotor, a fluid pressure cylinder having a restricted discharge port, a piston operable in said cylinder, a reservoir above the cylinder and above the piston for pressure fluid, a passage between the charge into the rotor comprising a tubular member extending into therefor and having a port in the form of a slot in the under side thereof, and walls extending upwardly from the sides and ends of said slot within the tubular member, said walls forming a passage having a cross sectional area substantially the same as the area of said slot.

1'7. In a machine for separating liquid from solids, the combination of a rotor, a housing enclosing the rotor, a scraper for removing solids from the rotor, a chute extending through the housing and having its upper end disposed within the rotor for receiving and discharging solids removed by the scraper, means located exteriorly of the housing for moving the scraper between an operative position for removing solids and a position across the upper end of said chute for closing the latter, and means within said chute for connecting said scraper moving means with said scraper.

said reservoir and said restricted port, and means responsive to movement of said spreader away from the fill-mass-for operating the piston to displace fluid from the cylinder through said restricted port to said reservoir.

15. In a machine for separating liquid from solids, the combination of a rotor, a spreader movable toward and from the fill-mass for engagement therewith as the fill-mass accumulates in said rotor, a pressure cylinder having a restricted discharge port, a piston operable in said cylinder, a reservoir above the cylinder and above the piston for pressure fluid, a passage through the piston to the reservoir, a relief valve in said passage, a passage between said reservoir and said restricted port, and means responsive to movement of said spreader away from the fill-mass for operating the piston to displace fluid from the cylinder through said restricted port to said reservoir.

16. In a machine for separating liquid from solids, the combination of a rotor comprising a wall for collectin g --fill-mass, means for feeding 18. Ina machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a wall of progressively increasing thickness, a charge control valve, time control means for opening the charge control valve and for closing said valve after a predetermined time interval, means for causing said charge control valve to close within said time interval, and means controlled by the quantity of fill-mass in said rotor for operating said last-mentioned means.

19. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a wall of progressively increasing thickness, a charge control valve, time control means for opening the charge control valve and for closing said valve after a predetermined time interval, means for causing said charge control valve to close within said time interval, and feeler means controlled by the thickness of fill-mass in said rotor for operating said last-mentioned means.

20. In a machine for separating liquid from solids, the combination of a rotor comprising a wall for collecting fill-mass, means for feeding the charge into the rotor comprising a conduit extending into the rotor, a discharge chute within said rotor forming an extension of said conduit for directing material from said conduit into the separating space of the rotor, said discharge chute comprising a passage in the bottom of said extension and an upstanding wall surrounding said passage to form a dam over which material may flow into said passage, and said conduit being provided with an opening below the upper edge of said wall and communicating withthe exterior of said rotor to permit drainage of liquid therefrom to a point outside of said rotor.

21. In a machine for separating liquid from solids, the combination of a rotor comprising a wall for collecting fill-mass, means for feeding the charge into the rotor comprising'a conduit extending into the rotor, a discharge chute within said rotor forming an extension of said conduit for directing material from said conduit into the separating space of the rotor, said discharge chute comprising a passage in the bottom of said extension and an upstanding wall surrounding said passage toform a dam over which material may flow intosaid passage, said wall extending axially of the extension through substantially the entire length thereof and terminating short of its upper portion, whereby to direct the charge into said rotor inthe form of a substantially continuous sheet of substantially uniform thickness extending across substantially the full axial width of said rotor.-

22. In a machine for separating liquid from solids, the combination of a rotor comprising a wall for collecting fill-mass, means for feedin the charge into the rotor comprising a conduit extending into the rotor, a discharge chute within said rotor forming an extension of said conduit for directing material from said conduit into the separating space of the rotor, said discharge chute comprising passage in the base of said extension and lying axially of the rotor through substantially the entire width thereof and a wall surrounding said passage to form a dam over which the material may flow into the passage, whereby to direct the charge into said rotor in the form of a substantially continuous sheet of substantially uniform thickness extending across substantially the full axial width of said rotor, said tubular member being provided with an opening below the upper edge of said wall in a portion thereof lying exteriorly of said rotor to permit drainage of liquid therefrom to a point outside of said rotor.

23. In a machine for separating liquid from solids, the combination of a rotor, means for feeding fill-mass into the rotor to form a wall of increasing thickness, a feed valve controlling the operation of said feeding means, fluid pressure operated means operatively connected to said valve and adapted to maintain said valve in open position, electro-magnetic means for controlling the operation of said fluid pressure means, means independent of said electro-magnetic means for controlling the operation of said fluid pressure means to effect closure of said valve independently of the operation of said electro-magnetic means, and a feeler within the rotor operatively connected with said independent means to control the operation thereof in accordance with the thickness of the fill-mass within said rotor.

NATHANIEL BREWER.

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