US3451550A - Centrifugal machine - Google Patents

Description

June 24, 1969 B. G. Cox ,4s1,5so

I CENTRIFUGAL MACHINE Filed June 12, 1967 sheet I of s INVENTOR. BRADLEY G. Cox

June 24, 1969 B. G. Cox 3,451,550

CENTRIFUGAL MACHINE Filed June 12. 1967 sheet Z of s FIG. 3.

INVENTOR BRADLEY G. COX

June 24, 1969 B. G. cox 3,451,550

CENTRI FUGAL MACHINE Filed June 12. 1967 Sheet 3 of 3 INVENTOR. BRADLEY G. COX

United States Patent O 3,451,550 CENTRIFUGAL MACHlNE Bradley G. Cox, Saginaw, Mich., assignor to Baker Perkins Inc., Saginaw, Mich., a corporation of New York Filed June 12, 1967, Ser. No. 646,156

Int. Cl. B01d 33/02 U.S. Cl. 210-78 12 Claims ABSTRACT OF THE DISCLOSURE A continuous self-discharging centrifugal separator having orbitally and axially rotating perforated baskets including at least one radially inwardly extending annular shelf forming at the interior of each basket wall a V- shaped or U-shaped product annulus. The rapidly orbiting baskets are positively rotated around their own axes at a predetermined, very slow rate in the neighborhood of 2-3 revolutions per minute, and the solids freed from the liquid are continuously centrifugally thrown oif the shelves to an annular discharge chute. The liquid-*solid mixture is initially delivered to a Zone radially intermediate the extreme inner and outer peripheral portions of the baskets relative to the orbital axis.

This invention relates to a centrifugal machine for the separation of solid particulate components from the liquid components of slurries, suspensions or the like, and more particularly to a continuous type machine for the separation of the constituents of mixtures of liquids and particulate solids.

BASIS OF THE INVENTION Continuous separators having a multiplicity of perforated baskets in generally vertical Orientation are known in the art. In one type of these machines the baskets are orbited at a high speed about a vertical main axis, and at the same time they are rapidly rotated about their own axes. A screw thread or spiral blade is provided which forces the material to slide gradually downwardly along the path outlined by this spiral blade. The rapid rotation of the basket around its rotational axis, in combination with the orbital rotation of the basket, results in a pulsation of the liquid, contained in the solids, back and forth in the machines in question and detracts from the effectiveness of the machine. Feed rates must be kept low and the sliding and rolling of the solid particles on the screw thread along the perforated wall resuts in damage to the particles and breakage which is undesired With many products, such as crystallized sugar.

It is an object of the present invention to provide a novel centrifugal machine and method of centrifuging which is capable of a high rate of production, and at the same time separates solids of the highest quality.

It is another object of the invention to provide a novel centrifugal machine easily adapted to single or multiple stage processing and in which the slurry is delivered to a predetermined Zone in the orbiting baskets.

Other objects will become apparent from Ithe attached drawings, and from the following detailed description of the invention.

DRAWINGS With reference to the attached drawings, FIGURE 1 is a sectional front elevational view of one embodiment of the centrifugal machine.

FIGURE 2 is a sectional plan view taken on the line 2-2 of FIGURE 1.

FIGURE 3 is a vertical sectional view of another embodiment of the centrifugal machine.

FIGURE 4 is a vertical sectional view of still another embodiment of the centrifugal machine.

ice

DETAILED DESCRIPTION OF THE INVENTION The present invention permits the continuous separation of solid particulate constituents from the liquid constituents of many slurries, suspensions, or other mixtures of solids and liquids with great efiiciency. In the machine and the method of the present invention, strong orbitally obtained centrifugal forces are maintained on a given volume of the 'slurry for a time suflicient to permit the removal of the desired amount of the liquid constituent. The solid particulate material retained is then progressively moved into a product deposition Zone where it is deposited on an annular shelf-like support and thereafter is subjected to centrifugal forces which moves it to an annular collection member. If desired, the separated solid product may be redeposited in another liquid removal zone further down in the basket, as in the embodiment of the invention illustrated in FIGURES 3 and 4, Where the steps of the process are repeated once or several times, until the product has the desired degree of dryness or freedom from the liquid constituent. In the multi-stage operation, the solid product is passed lthrough a plurality of superposed liquid removal Zones in the just described manner in a cascade type operation. The provision of vertically spaced, annular shelf-like product supports around the inner periphery of the baskets is advantageous in that the machine may be operated with high loads without the danger that product portions of different liquid content will mix as they are forwarded through the steps of the process. The retention time of the product in the various Zones may be controlled by the rate of positive axial rotation of the baskets. In this manner the efiiciency of the machine can be kept at a maximum, and a final product of a desired dryness, or of a liquid content of a predetermined low level, can ibe recovered.

Additional benefits are achieved, if the fresh slurry or other mixture of solid and liquid material is initially delivered to a Zone in the baskets, wherein the centrifugal forces are directed predo-minantly tangentially to the perforated wall of the circular baskets. In the machines to be described, the mixture of solid and liquid components is gradually moved from the product supply Zones toward `and through the liquid removal Zones by the slow positive rotation of the basket means around their axes at a predetermined rate and is subjected to gradually increasing centrifugal forces which do not fractionate the solid components.

The machine of the present invention is distinct from the known machine mentioned by having driving means which provide a slow positive axial rotation of the basket means around its own axis at a controlled predetermined rate corresponding to the liquid removal cycle. The axial rotation of the basket around its own axis is of an order low enough to avoid the generation of centrifugal forces of any noticeable magnitude so that the removal yof the liquid is substantially effected solely by the centrifugal forces generated by the orbital rotation of the baskets. In other words, the sole purpose of the axial rotation of the basket is to gradually move the product to be separated 'from the product deposition Zone through the liquid removal Zone to the product removal or discharge Zone, respectively, and to control the rate of forwarding of the product through the Zones. For this purpose, each basket may be axially rotated by gears driven by a main shaft means as illustrated hereinafter. With this arrangement the axial rotation of the baskets and the direction of their rotation is the differential between the rate at which the basket assembly is rotated as a unit, and the rate at which the central gear is rotated as a result of rotation of the main shaft.

Referring now more particularly to FIGURES 1 `and 2 of the drawings, a vertical main shaft is journaled and axially secured in a bearing 11 which is enclosed in a casing 12. The casing 12 is fixedly supported by structural frame members 13 and 13a. To the top end of shaft 10 is keyed a drive gear 14, and to the lower end of shaft 10 is keyed a bevel gear 15.

Independently rotatably mounted on shaft 10 is a basket assembly generally designated 16 and comprising a pair of orbiting and also axially rotatable baskets 17. The basket assembly 16 includes a generally vertical sleeve portion 21 which is journaled on the central portion of shaft 10. The baskets 17 orbit about the axis a of shaft 10 and revolve also about their own axes b. At the lower end of sleeve 21 tubular stub shalfts 22 extend downwardly at au angle to the main shaft 10. Above the inclined tubular stub shafts 22 an annular feed chamber 23 is formed 'by a side wall 24 and an annular bottom wall 25. The chamber 23 has an annular feed opening 26 at its upper end and keyed or otherwise suitably connected to wall 24 is -a drive pulley 28. Through top opening 26 a feed tube 29 delivers the mixture of solids and liquids to be separated in the machine.

The orbiting baskets 17 are enclosed by a wet housing generally designated 30 having a top wall 31 which is secured to the feed chamber wall 24. The cylindrical wall 32 of the housing 30 projects downwardly into a stationary dry housing generally designated 33.

Each basket 17 has essentially -the shape of an inverted tilted bowl and comprises a top plate 37 to which is joined an outwardly extending frustoconical wall portion 38 having a lower generally radially inwardly extending shelf or wall portion 39. The angle of inclination of wall 39 is such that its radially inner portion relative to axis a is horizontal during rotation and it terminates to provide a central discharge opening 40 at the bottom of each basket 17. Fixed on each top plate 37 is a plate 41 having `*an integrated bevel gear 42 in mesh with the bevel gear on the main shaft 10. Each bevel gear 42 is journaled on one of the tubular shafts 22. It will be observed that the lower end of each tubular shaft 22 is threaded, and that a cooperatively threaded product delivery nozzle generally designated 43 is mounted thereon. Each nozzle 43 includes a horizontal tubular portion 44 communicately connected to the bore of one of the tubular shafts 22 and extending generally perpendicularly to a diametral line 45 intersecting the outermost peripheral portion 46 of each basket 17 relative to axis a. Each nozzle has its discharge opening 47 located in -a basket 17 in a position close to or adjacent the perforate wall section 38 of the basket.

It will be observed that the stationary dry housing 33 has an annular solids collecting channel generally designated 48. Mounted for rotation with -the cylindrical -wall 32 of wet housing 30 by means of braces 49 is a circular rotary bottom plate or pan 50, which has an annular circular flange 51 to which are fixed rotary scrapers 52 received in the channel 48 and a frustoconical discharge bafiie 53 to which the braces 49 connect. The discharge baflle 53 extends upwardly through the discharge openings 40 in baskets 17 to direct the separated solids downwardly. The lower section of each scraper 52 'is joined to the flange 51 of the pan 50 and has the general shape of the solids collecting chamber 48. At its lower end the outwardly inclined baflie 53 has a ring-like curb 54 with a dependent annular skirt 55.

The stationary housing 33 includes a ring-like channel portion '56 which serves as a means for collecting and channeling the liquid expelled in the machine to an outlet 57. A ring member 58 joins the channel 56 with the solids collection channel 48 which includes a side Wall 60, a bottom wall section 61, and a frustoconical wall section 62. The rotary scrapers 52 travel essentially in wiping contact with the walls and bottom of the 4 product collection channel 48, pushing the solid product to a product discharge opening 63.

In operation, drive pulley 28 is connected by suitable belt means or the like (not shown) to an electric motor or other suitable drive means and the rotary basket assembly comprising the feed chamber 2.3, the baskets 17, discharge baffle 53, liquid collecting housing 30, rotary pan 50, scrapers 52, and the feed nozzles 43 are orbitally rotated at a high rate of speed about axis a, i.e., 1700 r.p.m. The gear 14 is meshed with a suitable positively driven gear and driven by the same or another electric motor at a similarly high rate of speed, i.e., 1698 r.p.m. so that the baskets 17, in consideration of the ratio of bevel gears 15 and 42, revolve about their axes b at a rate of only a few axial revolutions per minute, or less, as may be needed or desired for the particular product mixture being separated in the machine. If bevel gears 15 and 42 have a one to one ratio as in the drawings, the rates at which gear 14 and pulley 28 are driven dilfer only by a few revolutions per minute, e.g., two revolutions. At this rate of revolution about axes b, substantially no centrifugal forces are developed which would in any way oppose the centrifugal forces developed by orbital rotation. The orbital rotation must produce centrifugal forces of at least 25 times gravity (25 Gs) at points 46 and a force of at least 1 G at the points 46a diametrically opposite to effect solids discharge in the manner to be described.

Referring to FIGURE 2, the basket 17 shown at the left rotates in the direction indicated by the arrow c. The basket assembly, including the housing 30, rotates in the same direction, as indicated by the arrow d. A slurry or other mixture of solids and liquids is introduced through feed pipe 29 into feed chamber 23 and passes through the aperture 26 and tubular shafts 22 to the nozzles 43 and out openings 47 (FIGURE l). The mixture of solids and liquid is deposited adjacent the perforated conical walls 38 and 39 of the basket in a product deposition zone 70, i.e., in an area in which the centrifugal forces, in the direction through the walls of the basket, are low. As the basket is slowly axially rotated in the direction of the arrow c the deposited mixture is moved into the main liquid removal zone 71, where it is subjected to centrifugal forces acting with gradually increasing strength in a direction through the walls of the basket, with maximum forces acting perpendicularly to the perforated wall area approximately at point 46. As the product continues to revolve, it leaves the main liquid removal zone and enters a zone in which the centrifugal forces decrease, because of the smaller radial distance from the orbital axis a, and the forces finally then act oppositely with respect to a particular portion of the wall of the basket 17, due to the change of position of this Portion of the wall. As the product enters this product deposition or collection zone 72, the centrifugal forces of orbiting rotation tend to fling the separated solids outwardly away from the walls of the basket and off the wall 39 serving as a product supporting shelf to the solids collection channel 48. The solid product is defiected by the baffle 53 and slides down into the product collecting channel 48, and then is pushed by scrapers 52 to the product outlet 63.

In the particular machine illustrated in FIGURE 1 the centrifugal forces in the zone 72 at points 46a are a small fraction of the centrifugal forces in the liquid removal zone, i.e., a minimum of 1/30 of the forces at points 46 being required to effect discharge, and are exerted in an opposite direction with respect to the basket walls. Thus, extremely effective forces are available for separating the liquid components, and only the required moderate forces are utilized to effect the dislodging of the solid particulate material from the product supporting shelf 39 of each basket 17. The axially tilted baskets 17 illustrated in FIGURE 1 make possible the most effective separation of the liquids in the liquid removal zone,

and the smooth removal of the solids in the solids collection zone. The unique shape of the baskets 17 permit the wall areas to fulfill different functions in the different zones. The angle of slope of the upper conical wall 38 is such that the wall area is approximately vertically oriented in the product collection zone 72. In the liquid removal zone 71 this same wall slopes outwardly at an angle twice that of the inclination of the rotational axis b of the basket 17, forming in that area together with the lower inwardly inclined conical wall 39 a deep, pocketlike cavity or product annulus which is adapted to hold a relatively large quantity of liquid-solid mixture. The angled perforated wall in the liquid removal zone provides a large draining area and permits the separation of liquid over a larger area of wall than would be the case if the baskets were cylindrical in shape. As the liquid-solid mixture becomes depleted of liquid components, it is moved toward zone 72 where the inwardly inclined wall section 39 of the lower conical wall 39, i.e., the product supporting shelf, is substantially horizontal. This generally horizontal Orientation in the zone 72 permits the solids to smoothly slide off the shelf to the collection channel 48.

Another embodiment of the invention wherein separation is axially progressive in a series of axially spaced basket portions is illustrated in FIGURE 3 and includes a vertical main shaft 102 journaled in an upper bearing 103 and a lower bearing 104. The upper bearing 103 is mounted in a casing 105 which is rigidly supported by structural steel frame members 107 and 108. The lower bearing 104 is mounted in a casing 109 which is also structurally supported by the frame member 108.

To the top end of shaft 102 is fixed a drive gear 115 which is meshed with suitable driving means (not shown) and on the central portion of the shaft a bevel gear 116 is keyed as shown.

Above the bevel gear 116 a tubular bearing 117 is journaled on the shaft 102 and forms a part of a rotary basket assembly generally designated 118. The assembly 118 also includes an annular product feed chamber 119 formed by a ring-like bottom wall portion 120 and an outer vertical side wall portion 121. In the top of chamber 119 is an annular feed opening 122 which admits the stationary slurry delivery tube 123. The chamber 119 is of increased diameter at its lower end as at 125 and tubular shafts 126 which are inclined at an acute angle to the main shaft extend downwardly from the chamber 119. At the lower end of each tubular shaft 126 a nozzle assembly 127 with a horizontal outlet nozzle 128 is provided as in the previous embodiment of the invention, opening to a similar product deposition zone in each upper basket section.

Above each nozzle assembly 127 a bevel gear 132 is journaled on each tubular shaft 126 and is fixed to a circular top plate 133 provided for each generally cylindrical basket 130. The lower end of each basket 130 is provided with a circular dependent flange 134 which is journaled by a bearing 135. Each bearing 135 is supported by a radially extending arm 138 extending from a rotary circular bottom plate 136 which has a hub 137 journaled on the lower portion of main shaft 102 above the bearing 104. The baskets 130 are enclosed by a rotary wet housing generally designated 140, which is fixed by its top plate 141 to the feed chamber wall 121 and has a cylindrical wall 142 projecting downwardly into a stationary dry housing generally designated D. The whole basket assembly 118, including feed chamber 119, baskets 130, and housing 140 is rotated about the axis a by a drive pulley 142, which is fixed to the wall 121 of feed chamber 119. The drive pulley 142 may be connected by belts or other suitable means (not shown) to a rotating power source such as an electric motor. 'The stationary circular housing D includes an outer annular liquid collecting channel 151 with a liquid outlet 152, and an inner ring-like channel 153 for collecting solid product discharged from the baskets 130, the channel 153 having a downwardly directed outlet 154 for the solid product.

The generally cylindrical multi-step baskets include a plurality of cylindrical stacked perforated side Wall sections having downwardly inclined frustoconical bottom shelf portions 161 and upwardly inclined frustoconical top wall members 162. The members 160, 161 and 162 define product receiving annuli 163 of generally U- shaped cross-section. It is to be noted that an upppermost product annulus 164 has a considerably larger cross-section to accommodate the larger volume of the freshly iutroduced liquid-solid mixture.

Scrapers 164 disposed in the solids collection channel 153 similarly connect to the pan 136 and an annular baffle 165 which is provided as before. Braces 166 may be provided to support the baflle 165, Scrapers 164, and pan 136 for rotation with the wet housing 140.

The operation of the just described embodiment of the machine is similar to that of the centrifugal machine described hereinbefore and illustrated in FIGURES l and 2. The machine is started and the basket assembly 11 8 is rapidly rotated by the drive pulley 142. The main shaft is likewise rapidly rotated by the gear 115 and its rate of rotation is adjusted so that the baskets 130 are slowly rotating around their own axes at the few revolutions per minute desired. The product mixture of liquid and solids is then introduced through feed pipe 123 into the rotating feed chamber 119 and through tubular shafts 126 and nozzle assemblies 127 to the product deposition zone in the uppermost product annulus 164 of each basket 130. As previously, the liquid-solid mixture deposited is gradually moved into a liquid removal zone in the uppermost annulus at point 46, where much of the liquid is drained away through the uppermost perforated cylindrical wall 160, and flows down to be collected in the stationary liquid collecting channel 151. The solid product, freed in part from the liquid, is then moved, by the continuing slow axial rotation of the basket, to the product collection zone in the uppermost annulus of each basket adjacent the main shaft 102, where centrifugal forces tend to move the product toward the axis of the basket, and into the next uppermost product annulus 163. This cycle is repeated in each annulus 163 until the remaining solids are discharged into the product collection channel 153 and are pushed by rotating scraper blades164 to the product outlet 154.

It is to be noted that the inclination of the annular shelves 161 in the basket and the inclination of the rotary axis of the basket are adjusted such that the shelf sections are, in the product removal zone, approximately horizontally disposed, and such that the product thrown off the shelves and the product annuli 163` flies, under the effect of the centrifugal forces, and of gravitational forces, into the opposite side of the next lower product annulus. In this manner, no additional guides or baifles are needed to direct the product in its stepwise travel downward through the basket.

The solid product is, by the repeated redeposition in new perforated areas of the basket, loosened up so that the liquid removal becomes most effective. The outwardly inclined disposition of the baskets in this embodiment of the invention subjects the mixture to gradually increasing centrifugal forces as the product travels down through the basket, due to the gradually increasing distance of the product from the axis of orbital rotation. Because of the longer retention time of the product in the machine, higher speeds of rotation about both axis a and axes b may be employed and it is suflficient that a minimum centrifugal differential force of 1 G be available to discharge the product at points 4611.

The embodiment of the invention illustrated in FIG- URE 4 employs a central, generally vertical main shaft 201 journaled in a bearing 202 at its upper end and in a bearing 203 at its lower end. The bearing 202 is supported by structural frame members 204 and 205 and the bearing 203 is supported by a base frame `member 206. A drive gear 207 is keyed on the upper end of shaft 201 and a gear 208 is keyed to the shaft intermediate its ends.

At the upper end of the main shaft 201 a tubular bearing 210 supports a rotatable basket assembly generally designated 211. The basket assembly 211 includes an annular feed chamber 212, formed by a cylindrical side wall section 213 and an annular bottom wall section 214. Provided in the top of the chamber 212 is an opening 215 to accommodate a slurry delivery pipe 216. A main drive pulley 218 is fixed to the side wall section 213 of the feed chamber 212 and is connected by a suitable belt or other driving means (not shown) to a suitable rotary power source such as an electric motor.

Dependent stub shafts 225 are provided on the feed chamber 212 as shown and connect an annular passage 226 with passages 228 which lead to horizontal nozzles 229 having discharge openings 230. Each of the nozzles 229 discharges into the uppermost section of a multi-shelf basket generally designated 231, into a product deposition zone as before. A basket drive gear 233 in mesh with the central gear 208 is fixed to the top plate 234 of each basket 231.

The basket assembly is enclosed by a rotary wet housing generally designated 236 which has its top plate 237 connected to the lower end of feed chamber 212 and Which has a vertical cylindrical wall 238 projecting downwardly into a lower stationary collection housing generally designated 239. The rotational axes b of baskets 231, it will be observed, are vertical and parallel to the main axis a of orbital rotation in this embodiment of the invention.

Each generally cylindrical basket 231 has a circular discharge opening 240 at its lower end and a dependent flange ring 241 surrounding the discharge opening extends into an annular bearing 242 which is supported by braces 243 in a manner which will be later described. A central ring member 244 journaled on the main shaft 201 also functions to receive the basket fianges 241. Each basket 231 is made up of six generally cylindrical perforate side wall sections 232 separated by horizontally disposed annular product supporting shelves 250 and top walls 250a, each section defining a circular product receiving annulus 251, having a generally U-shaped cross-section.

A product discharge baifle 252 projects through the lower discharge opening 240 of each basket to a height opposite the lowermost top wall 250a and, as previously, is connected with scraper blades 253 which are contoured so as to be in wiping engagement with the walls and bottom of an annular channel generally designated 254 for collecting the discharge solid product. The discharge baffle 252 and scraper blades 253 are connected to the basket assembly so that they rotate with the basket assembly. Also semi-conical cascade baflies 258 are mounted in place opposite each annulus 251 on rods 260 which are fixed between the nozzle assembly members 230 and the lower discarge baie 252. In this manner the cascade bafiies 258 which guide the product from one basket section to the basket section underneath progressively are fixed within the basket and participate merely in the orbital rotation of the basket assembly.

The stationary housing 239 also includes an outer annular channel 265 for collecting the liquids separated from the product mixture, which has a liquid outlet 266, as well as the inner wide annular channel 254 for collecting the solid product discharged from the baskets 231. The solid material in channel 254 is forwarded by rotary scraper blades 253 to a vertical product outlet 268.

The operation of this embodiment of the machine illustrated in FIGURE 4 is very similar to the operation of the machines described previously. The basket assembly is rapidly rotated by the drive pulley 218 and the main shaft 201 is likewise rapidly rotated by gear 207 at such relative rates that the baskets, orbitally rotating at a high rate, slowly rotate around their own axes b at the rate which is required by the product retention time in each section of the basket for the separation of the solids from the liquids. The product mixture of liquid and solids is fed through feed pipe 216 and feed chamber 212 to the baskets 231 where it is deposited in the product deposition zone adjacent the perforated cylindrical wall section of the uppermost product annulus 251. The product mixture is then slowly moved into and through the liquid removal zone in the upper annulus, where much of the liquid is removed, and on to the product collection zone in the upper annulus adjacent the main shaft 201, where the product is thrown out of the uppermost product annulus 251 into the interior of the basket and against the uppermost cascade Abaffle 258 which directs the product downwardly so that it is deposited in the product deposition zone of the next uppermost product annulus 251. Additional liquid is removed in this stage and the product is slowly forwarded, as the basket rotates, to the product removal zone in the next uppermost annulus, where it is thrown olf against the next lower baffle 258, etc., until the solid product has passed in cascade-like manner through all the sections of each `basket 231 to the discharge baflie 252 which directs it to channel 254. The liquid expelled through the perforate wall sections of the basket at the various stages is collected by housing 236 and flows downwardly into channel 265 for recovery at liquid outlet 266.

The separatory machine of the invention has been illustrated and described hereinbefore with a pair of opposite perforate basket means. If desired, the number of baskets, orbitally rotating around the vertical main axis, may be increased provided the baskets are arranged in balanced manner around the main axis of orbital rotation. The machine of the present invention is essentially selfbalancing in spite of the uneven distribution of the weight around the periphery of each basket. The machine is selfdischarging in the sense that no pushers or scrapers or other means are required for the removal of the separated solids from the baskets. The discharge of the solids from the baskets 231 by the Utilization of centrifugal forces only avoids crystal Ibreakage or other damage to the solid particles. Generally, it is desired that the baskets rotate axially in the same direction in which the basket rotates orbitally around the main axis as illustrated in FIGURE 2. However, there may be exceptions to this general rule if special conditions prevail with certain mixtures of solids and liquids to be separated or if special effects are to be achieved.

If desired, the machine may be provided in a suitable manner With means for washing the separated solids. In the machines utilizing multi-step baskets, the washing may be effected while the product is disposed in one of the lower product annuli. The washing liquid may, for instance, be applied to the solids while they are in the liquid removal zone.

'The novel machine of the invention achieves a high throughput capacity with a minimum power requirement and with low maintenance. The discharged products are of high quality and uniformity.

I claim:

1. A centrifugal machine for the continuous separation of solids and liquids comprising: a basket assembly mounted for rotation about a generally vertical main axis; said basket assembly including a plurality of circumferentially spaced basket means mounted for orbital rotation about said main axis and for `rotation about their own axes; each basket means including at least one peripheral perforate wall portion and at least one peripheral annular product supporting shelf means and having a product discharge opening at its lower end; chamber means under said shelf means -for the separate collection of separated liquid and solids in a radially outer and inner chamber, respectively; a bafi'le extending upwardly and inwardly into the lower end of said plurality of basket means to deflect solids discharged centrifugally from said shelf means to said inner chamber; driving means for rotating said basket assembly about said main axis and said basket means about their own axes; and means for feeding a mixture of solid particulate material and a liquid into said baskets.

2. The centrifugal machine of claim 1 wherein the said chamber means for collecting separated solids is a downwardly inclined annular channel disposed below the rotating basket assembly, and the disc-harge balfle is provided with dependent product forwarding means wiping said annular channel.

3. The centrifugal machine of claim 2 wherein the said chamber means is generally horizontal and stationary.

4. A centrifugal machine for the continuous separation of solids and liquids comprising: a basket assembly mounted for rotation about a generally vertical main axis; said basket assembly including a plurality of circumferentially spaced basket means mounted for orbital rotation about said main axis and for rotation about their own axes, each basket means including a plurality of superposed peripheral perforate wall portions having axially spaced peripheral frustoconical product supporting shelves and providing a plurality of `superposed product annuli around the inner periphery of the lbasket means; chamber means for the separate collection of the separated liquids and solids; and means for feeding a mixture of solid particulate material and a liquid into each basket means into the upper product annulus of the basket means.

5. A centrifugal machine comprising: generally vertically disposed main drive shaft means having a first axis of rotation; a plurality of circumferentially spaced baskets mounted thereon for orbital rotation about said first axis of rotation; each basket including a perforate peripheral side wall portion and each basket being mounted for rotation about an axis of rotation inclined downwardly and outwardly relative to said first axis of rotation; each basket having an annular radially extending generally frustoconical solid product `supporting perforate shelf terminating short of the axis of each basket so as to proivde a discharge opening for the solid product; said shelf being inclined radially to the axis of rotation of the basket in which it is mounted; means for continuously feeding a mixture of solid particulate material and of a liquid into said baskets; driving means for rapidly rotating said baskets orbitally and driving means for independently rotating each of said baskets relative thereto about its own axis; chamber means around the baskets for collecting liquids expressed centrifugally through said perforate peripheral wall portions of the baskets; and means for collecting solids from said discharge openings of the baskets.

6. The combination defined in claim 5 in which said side wall portion and shelf of each basket are so inclined that adjacent said first axis of rotation the side Wall portion generally parallels said first axis and said shelf is generally horizontal.

7. The centrifugal machine of claim 5 wherein each basket comprises an upper circular member to which is joined an outwardly flaring frustoconical side wall portion and an inwardly inclined lower frustoconical shelf portion, the angle of inclination of said lower shelf portion relative to the upper circular top portion corresponding approximately to the angle at which said axis of rotation of the basket is inclined to said generally vertically disposed first axis of rotation, and the angle between said upper wall portion and said lower shelf portion being approximately a right angle.

8. The centrifugal machine of claim 7 wherein perforated side slip preventing, triangular baflles are fixed to the frustoconical wall sections such that their plane is generally radially disposed and generally parallel to the said axis of rotation of the basket.

9. A method for separating a mixture of particulate solid product removal zone adjacent the orbital axis; and ponents by the application of centrifugal forces comprising the steps of: feeding a mixture of solids and liquid into an axially rotatable peripheral annulus having an axis of rotation and an axial discharge opening in a collecting shelf, rapidly rotating said annulus orbitally about another generally vertical axis of rotation so as to generate the centrifugal forces required for the separation of the liquid from the solid material in a zone most removed relative to the orbital axis; axially rotating said annulus at a slow speed developing no significant counteractive centrifugal forces adjacent the orbital axis, axial rotation of the annulus forwarding the remaining product to a solid product removal zone adjacent the orbital axis; and centrifugally removing the solid product from said shelf by means of the centrifugal forces generated by the orbital rotation of the annulus.

10. The method of claim 9 in which a plurality of superposed annuli are employed and in which the solid product is successively removed lby centrifugal force from the product removal zone of each of the annuli and is redeposited in each step in the next lower annulus until it is discharged from the lowermost annulus.

11. The method of claim 9 in which the feed mixture of solids and liquids is deposited in a product deposition zone in the annulus 1between the liquid removal and product removal zones and upstream of the liquid removal zone considering the direction of rotation of the annulus about its axis of rotation.

12. A centrifugal machine for the continuous separation of solids and liquids comprising: a basket assembly mounted for rotation about a generally vertical main axis; said basket assembly including a plurality of circumferentially spaced basket means mounted 4`for orbital rotation about said main axis and for rotation about their own axes; each basket means including a plurality of superposed peripheral perforate wall portions having peripheral axially spaced product supporting shelves and providin'g a plurality of superposed product supporting annuli around the inner periphery of the basket means, a series of cascade baflles provided in each basket means adjacent the superposed peripheral wall portions; means mounting said baflles for orbital rotation only; chamber means for the separate collection of the separated liquids and solids; driving means for rotating said basket assembly about said p main axis and said basket means about their own axes;

and means for feeding a mixture of solid particulate material and a liquid into each basket means near the upper end thereof.

References Cited UNITED STATES PATENTS 805,426 11/1905 Packer 210-325 1,040,373 10/1912 Michelsen 210-325 1,655,774 l/l928 Sansaricq 210-370 X 2,356,497 8/1944 Banning 210-377 2,368,876 2/1945 Terradas 210-325 X 2,435,665 2/1948 Woolaver 210-377 2,578,468 12/1951 Fleischer 210-374 2,626,055 1/1953 Hoyt 210-325 X 3,073,377 l/l963 Robinson 210-377 X FOREIGN PATENTS 278,327 12/ 1927 Great Britain.

REUBEN FRIEDMAN, Primary Examiner. I. L. DECESARE, Assistant Examiner.

U.S. Cl. X.R. 210-370, 373, 381

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