US2196651A - Mechanical dehydrator and roller mill - Google Patents

Description

April 9, 1940. E. F. ALLEN y IEUHAIICAL DEl'lY-DRATOR AID ROLLERIIILL Fund April 16. 193e 4 Sheets-Sheet 1 NVENTOR Engr/e FIA/len ATTORNEY Ap 9, 1940. E. F. ALLEN I MECHANICAL DEYDRATOR AND ROLLER IILL,

Fil-ed April 16.' 1936 4 Sheets-Sheet 2 La mn. n. mk am El.l WA m -E .A I', /rvf 0B E April 9, 1940 E. F. ALLEN l 2,196,651

u EcHANIcAL DEHYDRA'roR No lROLLER um.

Filed April 16. 193 4 Sheets-Shset 3 82 Iricg INVENTOR Ear/e F.' A/[e ATTORNEY April 9, 1940- E.v F. ALLEN 2,196,651

MECHANICAL bEHYDR-A'OR AND ROLLER IIILL Filed April 16. 1936 4 Sheets-Sheet' 4 fit1 -5- 5i-.

:NVENTOR E'AELE F ALLE/v,

ATTORNEY Patented Apr. 9,

UNITED STATES MECHANICAL DEHYDRATORAND ROLLER Earle F. Allen, Briai'cliii' Manor, N. Y., assignor,

by mesne assignments, to Stacom Process Corporation, Long Island City, N. Y., a corporation vof New York Application April 16,

9 Claims.

This invention is a continuation in part of my co-pending application Ser. No. 17,050, led April 18, 1935,for Mechanical dehydrator and process and apparatus, and consists mainly in the further development of certain of the various modifications of the original concept. disclosed in said earlier application.

The present application is particularly concerned with an apparatus in which the pressure applied by the inner roller is opposed by a roller y roll, the ring or hollow cylinder forming the other press member being freely rotatable and being driven by frictional surface contact with the inner roll, while in the prior application the power is applied to the ring and the roll is driven by friction. Another feature of the present invention is theprovision of such an apparatus in which the axes of the ring and rollers are in the same horizontal plane.

Also in the present application various forms and others shown in section on the plane denoted by the line I-I in Fig. 2 of a machine embodying my invention adapted to be operated by a worm driving gear.

Fig. 2 is a horizontal section on the irregular line 2-2 of Fig. 1, parts being broken away, and

Fig. 3 is a vertical section on the irregular line 3-3 of Fig. 2.

Fig. 4 is aside elevation with parts broken away of a gear driven type of apparatus employing a powerful spring for compression instead of hydraulic cylinders and having both the inner roll and the outer anti-friction roll positively driven by said gearing, and

Fig. 5 is a plan view of the device of Fig.- 4 with parts brokenaway and others shown in section. v

Fig. 6 is a plan view with parts broken away and others shown in sectionof a construction similar to that shown in Figs. 4 and 5 except that an hydraulic cylinder is employed instead of a spring and only the inner roll is gear-driven, and

1936, Serial No. '14,625

(Cl. 10U-47) Fig. '1 is a vertical cross section taken on line 1-1 of Fig. 6.

Fig. 8 is a detail cross section with parts broken away of a ring and inner roll like that of Fig. 1, showing in addition a special form of apparatus for feeding material continuously to the roll pass,

and v f Fig. 9 is a section on line 9--9 of Fig. 8.

Figs. 10 and 11 are perspective details of different forms of telescoping coupling which may be inserted in. worm shaft I9.

Fig. 12 is a diagram of the horn angle between a pressure surfaces in the machine of Figs. 4 and 5 and Fig. 13 is a similar diagram of substantially the same angle reproduced in the larger machine of Figs. 1 to 3.

Throughout the drawings like reference characters indicate like parts.

Referring to Figs. 1, 2 and 3, a two-part casing and frame is indicated at I, in which the moving parts of the mechanism are enclosed and supported. 2 indicates a freely rotating ring or open ended cylinder which may be provided with facing plates 23, 23, of harder material, and preferably. of slightly less width than the main body of the ring 2, which as here shown is supported in and between circular grooves 3, 3, formed in the side plates of the main frame. 4 indicates an inner roll located within and in contact with the inner facing plate surface of the ring 2 so that together they constitute a roll press when rotated. i 24 is an outer anti-friction roll bearing on the outer surface of ring 2 and supporting the same against the radial thrust 'of roll 4. 35 Shaft 5 of roll 4 is journaled in slightly movable journal blocks 'I and 8 and 9 is a cap for the front journal block. I0 is a fixed journal bearing for the shaft 5 of roll 24'in the form of a rigid cap cast in the rear frame plate, and II is a similar front journal bearing, but left open at the outer end to be closed by cap I2.

Bolts for fastening together various portions of the casing including these caps 9 and I2 are shown at I3, I3. j

The openings in the casing sides for the movable journal blocks 'I' and 8 are large enough to allow slight clearance for their horizontal motion within narrow limits, as indicated at I4, I4 (Fig. 2), and said blocks are mounted on the horizontally'extending splines I5, shown in cross section in Fig. 3 and in dotted lines in' the other figures. I

` Thel shafts 5, 5, are provided with graphite bushings 6 and I6 which are of the standard type u bushings having a plurality of fine radial perforations in each of which graphite is packed. When these are put into use a film of graphite forms immediately on the innersurfaces of said bushing or sleeve and persists indefinitely. The journal pressures required in the operating of apparatus according to my invention are so great that ordinary methods of journal lubrication with oil can not be used. Worm wheels I1, I1, are held fast .on the front ends oi' roll shafts 5, 5, by keys 29, 29, and cooperate with right and lett hand worms I8, I8, carried by the power shaft I9, which may be driven by anelectric motor such as that indicated at 82 in Figs. 5 and 6. Ball bearings for the worm shaft are indicated 'at 20, 28, and 2| indicates a spline connecting the v worm in the movable journal block 3 to the shaft in such manner that it may have thenecessary slight movement lengthwise of the latter.` 'Ihis movement may, however, be otherwise rendered4 possible as by making shaft I 9' in two sections connected by some kind of a longitudinally yielding coupling, such as indicated in Figs. 10 and 11.

Removable plates 22, 22, of semicircular form are shown as being set in the side walls `of the casing and have portions of the guide grooves 3, 3, for the ring 2 cut intheir inner faces. Any necessary feed and discharge opening should be cut in at least one of said plates, one such being indicated at 25 in Fig. -1. Hydraulic cylinders 26, 26, are anchored to the frame and contain pistons 21, 21, connected to piston rods or plung; ers 61, 61, which have their outer ends resting against the movable journal blocks 1 and 8 respectively. Fluid under pressure is supplied to the cylinders through pipes 28, 28.

The grooves 3 in plates 22 should have enough clearance to permit ring 2 to always have full width bearings'on both rolls 4 and 24 when the pressure is applied by forcing liquid into cylinders 26, 26. Even when these cylinders are of medium size, say 41/2 inches in diameter, a hydraulic pressure of 2000 pounds or more to the square inch can easily be created therein which will exert a thrust of about 60,000 pounds or more on the shaft of roll 4 and force it against ring 2. If then the cellulose-bearing materials are fed between the opposite surfaces of 2 and 4 in a thin ribbon, perhaps only a few inches in width, the cell structures thereof are thoroughly crushed, and nearly all liquidycontents expelled. There should be an opening (not shown) in the rear casing plate 22 on a level with the lowest portion of the interior surface of ring 2, through which opening the expressed liquids can escape and be collected in any suitable receptacle. With the liquid much of the coloring matter and the noncellulose solids are also expelled.

In operating this embodiment of the invention oil or water is admitted to cylinders 26, 26, under very great pressure sufficient to produce a thrust of from 5000 to 9000 pounds or more per linear inch of contact between the inner surface of plate 23 of ring 2 and the surface of roll 4 (i. e., if the width of the roller is 4 inches the total force applied by the roller will be 20,000 to 36,000 pounds), said thrust being absorbed, of course, by the anti-friction roll 24. Then when worm shaft I9 is rotated in a counterclockwise direction, looking at Fig. 3, `theinner roll 4 and ring 2 will be given rotation in a clockwise direction, looking at Fig. l, and the anti-friction rollV 24 will be positively rotated in a counterclockwise direction. Any material introduced through a feed amanti known as oilless bearings consisting of Imetal openingl such as 23 will then fall on the inner surface of the rotating ring 2 and be carried up to the zone of maximum pressure between it and the inner roll, said line of greatest pressure extending, of course, along the horizontal plane in which the axes of shafts 5, 5, lie.

Any convenient form of roll scraper and discharge trough can be installed for removing the crushed material from the roll and ring surfaces, such as one of those indicated in Figs. 4-7.

Referring to Figs. 4 and 5, the main frame is there marked 3|, the ring 32, the inner roll 34, and the outer anti-friction roll 36. The supporting shafts for said rolls are indicated respectively at 35, 31, and a supporting idler for ring 32, shown at 33. In this construction the roll pressure is supplied to the external roll 36 by means of the extremely stiff helical spring 38, the shaft 31 of this rolly having a certain amount of horizontal play in the slots 39, 39, in the side walls of the main frame 3I. Pressure of spring 38 is adjusted by means of the screw 44 meshing in fixed nut 45 and carrying one-half oi ther thrust ballbearing 43 at its inner end, the other half of said bearing being carried by the movable plate 42 which serves as a thrust member against the outer end of spring 36. The inner end of said spring bears against the pressure fork 4I in which the roll 36 is supported by means of hubs 48, 40. Clips 46, 46, carried by said fork and bearing on the outer ends of said hubs serve to center the roll 36 in the fork.

lIn this construction, both rolls 34 and 36 are positively drivenby gearing from motor 62, said gearing comprising armature shaft pinion 41, gear 48 fast on countershaft 49 journaledin fixed bearings 60, 60, and carrying pinion 50 which meshes with gear 5I fast on shaft 52, which is journaled in and extends through the main frame, carrying the gear 53 on its front end whichmeshes with the intermediate gear 54, thereby transmitting motion to the gear 55 on the shaft 35 of the inner roll 34. The shaft 52 also carries gear 56 at the rear side of the casing which meshes with gear 51 on the shaft 31 of -the anti-friction roll 36, thus positively driving the latter in an opposite direction to that in which vthe roll 34 revolves. 58 indicates a combined scraper and discharge trough supported on brackets 59, 59, and bearing against'the outer surface of inner roll 34, and the inner surface of ring 32, while 6I, 6I, indicate Scrapers bearing against the side edges of ring 32. In operation the ring 32 and inner roll 34 are given rotation in a counterclockwise direction looking at Fig. 4 by rotation of the motor 62 in the proper direction, while outer roll 36 is positively rotated in a clockwise direction. The material to be treated is fecl in beneath the scraper 58 to the lower horn angle between the ring 32 and the roller 34. This material may be fed in by hand or-by a suitable mechanical means, such, for example, as illustrated in Figures 6, 7 and 8.

Referring to Figs. 6 and 7, a construction generally similar to that shown in Figs. 4 and 5 is illustrated except that only the inner roll 14, carried by shaft 15 journaled in frame 1I, is positively driven, the ring 12 and thrust roll 16 being frictionally driven therefrom. The gearing rotating roll 14 is similarl to that shown in Figs. 4 and 5 and the like parts are given like reference numerals.

Also in this form hydraulic cylinder 18 having piston 19 and inlet 60 for pressure fluid is substituted for the pressure spring 38 of Figs. 4 and 5,

the piston rod carrying they pressure fork 8| in which roll18 is journaled.

The ring 12 and pressure roll 14 are given rotation in the same direction as ring 32 and roll 34 in Fig. 4 by the motor and gearing, which are the same in both.

82 yindicates an inclined feed trough by'which raw material may be dschargedfinto the lower part of the interior of ring 12 and be carried up by rotation of the ring into and through the pressure zone between it and roll 1l. An inclined scraper and discharge trough which bears against the inner surface of the ring 12 and the outer surface of roll 14 at points spaced-away 180 from the line of contactbetween said ring and roll is indicated at 83. An idler roller journaled in frame 1l for supporting ring 12 is shown at 13 in Fig. 7.

My invention is operable on both dry and damp materials. With the former, the feed may be continuous as the sole purpose then is the crushing of the particles to utmost fineness, a thin layer of the materials being continuously fed upward to the limited compression zone where it will be subjected to enormous pressure between the moving surfaces of ring and roll. With the latter an additional and most important object is expressing as much as possible of the contained liquids and the subsequent maintenance of the separation between such constituents which has been effected in the pressure zone.

The last mentioned result is besteffected by an intermittent feed of the materials to the rolls when the simpler embodiments of the invention here shown are alone employed, the liquid expressed from any one charge `being given time to run down to the lowest portion of the ring interior and out a-t one side thereof before the succeeding charge is dumped into such interior. It may. however, be attained in part with the use of a continuous feed if a mechanism be installed such as that shown' in diagram in Figs. 8 and 9,

where la revoluble member or tedder, generally indicated at 90. is shown as journaled between side plates 22, 22, under the lower end of a feed chute or hopper 95, the upper end of which should protrude through a feed opening 25' in the rear plate. The tedder as there shown is composed of the-spool 9i having radial projections 92 uniformly distributed around its surface.- These may be in the form of paddles, as indicated. 93 is a supporting and driving shaft for such spool operatively connected by chain and sprocket gearing 94. or other mechanism to the shaft `Ei of roll l or other rotating element so as to revolve in the same direction as does ring 2. Beneath the tedder is a horizontal screen 96. An outlet for liquid is shown at 91 in the front plate .22.

a I In operation hopper 95 should be kept at least will be conveyed to the pressure zone.

' 96, thence to ow out through drain opening 91.v

partially lled with the garbage, waste vegetav tion or other finely divided fibrous material being treated. thus maintaining a mass of it 98 on screen 96. The rotating tedder 90 will continuously flirt or push small portions of this material to the left and distribute them in an even layer on the upwardly moving, inner wall of ring 2 by which it The thin film of liquid flowing downwards from such zone .will percolate through an upper, short section of the lowest stratum only of such upwardly traveling layer of material and collect under screen r' Thus the major portion of the incoming material will be kept out of contact with the' expressed liquid and none of it will be dumped in the liquid bath below the screen, as it would be if such screen and tedder were not employed.

Fig. 10 is a perspective detail of a. modification comprising a telescoping couplingv 8l in worm `shaft I'9to take the place of the spline 2l shown 6 in Fig. 1 in the worm I8 driving the movable roll l4, and is an air opening therein to prevent air than to hide it in movable jqurnan mock 1, as. 20' indicated in Fig. 1.

As the high pressures employed in using my invention produce a large amount of friction if there is any relative movement between theadjacent surfaces of ring and roll, when in contact or when 25 having only a very thinlayer of material between them, and that would absorb a considerable amount of extra power in operating the press, I usually prefer to so design the gearing that each pair of surfaces thus in rolling contact '(or ap- 30 proximating such contact) shall have the same peripheral speed.

When both inner and outer rolls are positively driven by the gearing, as in Figs. 1 to 5, it is necas essary that the surfaceA of the outer rolls shall travel'as much faster than does that of the inner one as the speed of the outer surface of the ring exceeds that of its inner surface-to accomplish the above stated desired result. l In the constructions shown this result is obtained by making the 40 length-ratio between the radii of the inner and outer rolls the same as that between the ring interior and exterior, and then having trains of driving gear for the two rolls designed to give each the same'number of revolutions per minute. The same result could, of course, be accomplished by having the revolutions per minute of each vary inversely as the inner and outer radii of the ring. while the radii of the rolls were made equal one 50 to another.

In all constructions in which one of thev pres' sure elements (ring and roll) is frictionally driven by the other there is necessarily a certain amount produce a minute 'difference 'in their respective 'peripheral speeds, especially when the layer of material being compressed between them isx somewhat slippery in character, as would be the case with most fibrous matter and garbage. It may 50 be that such action, which undoubtedly occurs to a minute extent, is helpful because it produces a slight grinding effect on the ribbon of material when going through the zone of maximum pressure. Any such action would, of course, be ag- 05 gravated by the modification shown in Figs.l 6 and '7 in which only the pressure roll is gear driven and both ring and anti-friction roll are dragged around by friction.

In all cases the high pressures used so compact 70 as well as crush, the particles of material going through the roll pass-that they issue therefrom as a thin, self sustaining ribbon made up of minute, cohering particles, usually adhering to the surface' of the ring or of the roll. Particularly 75 pressure applied to successive minute areas of thin layers thereof by my apparatus causes the contained liquid to burst all, or nearly all of the cells of such material cellulose, and thereby put the crushed particles in the best possible condition for subsequent rapid and nearly complete air drying. This is a most important novel feature of lmy process and apparatus whether used to prepare garbage for use as a fuel, or to prepare any natural cellulose for further treatment in paper making or other of the known commercial processes in which pure cellulose is employed.

The greater portion of the crushed material usually leaves the pressure zone in the form of a compacted ribbon which adheres to the ring 2 until it is scraped off and so broken into' fragments.

In designing apparatus embodying my invention a compromise between conicting conditions or limitations is required. On the one hand the horn angle formed between the cross sections of the approaching surfaces of ring 2 and inner roll 4 must be sufhciently acute to prevent the material approaching its apex from slipping backward and so failingto enter the zone of maximum pressure, which means that the diameter of the roll must be fairly large in proportion to that of the ring interior. On the other hand the roll diameter must not be so large as to so restrict the space left between the other, opposite, surfaces of roll and ring as to unduly cramp and limit the space between said surfaces required for installation and operation of an efficient feeding mechanism.

In my original small machine, the proportions of which are accurately shown in Figs. 4 and 5, the diameter of ring'32 was 9 inches and the diameter of roll 34 was 6 inches. This produced a horn angle satisfactory for the purpose but left no sufficient space for a feed mechanism, and consequently the material was fed by hand into that machine.

If the same proportion between diameters is f.

preserved in a larger machine the horn angle will be even more acute and Aat least equally effective in action, but the free space then left for feeding mechanism, while-larger, might not be sufficient l the same horn angle used in such first appara--V tusat least until further experiments show some permissible increase in its acuteness to be safe and perhaps advantageous. Consequently I have shown in the machine of Figs. 1 to 3 a relative proportion of 2 to 1 between the diameters of ring and roll instead of the 3 to 2 proportion of Fig..

4. With aring diameter of 20 inches this reproduces substantially the same angle as the 9 and 6 inch dimensions of the original machine, and yet leaves suiicient free space for a feeding mechanism such as shown in Figs. 8 and 9, while keeping the over-al1 dimensions of the apparatus within convenient limits.

The shaded areas marked A in Figs.v 12 and 13 indicate about how far the operative section of the horn angie would extend when a layer of material of the predetermined thickness is being fed to the pressure zone on the inner surface of the ring. That is to say, no layer of material thick enough to be compressed at all before it had travelled to about the point P during rotation of either ring 2 or 32would ever be deposited thereon if the feed mechanism lwere properly adjusted.

In Fig. 12, showing this horn angle as existing in my first machine illustrated in Figs. 4 and 5,

this point P as shown has been located arbitrarily on arc 32 in Fig. 12 at a distance from the zero point on the scale there shown of about 21/2 inches, i. e., P-O equals 2.5 inches. The outer limit of the compression zone which begins there would be substantially indicated by the r'adius R of arc 32 passing through P and the center C of the ring. Such radius intersects arc 34 (struck from the center c of the roll) at X, and the distance P-X represents substantially the width of the mouth of the assumed standard horn angle which has been tried out successfully in the machine of Figs. 4 and 5.

"I'he problem in designing another machine in which this standard horn angle of Fig. 12 is to be reproduced as nearly as possible, can be solved graphically as follows:

The radius R of the ring interior 2 of such second machine will beiixed by considerations of desired over-all dimensions, &c. If such radius is to be 10 inches, as in Figs. 1 and 13, the arc 2 of such a circle of that radius should be drawn through the zero point on the scale from a center on the horizontal line 0-Z, such center not being shown in Fig. 13 because of limitation oi' space.

On this are the point P should be located at' the 4 same distance O-P of 2.5 inches from-0. A radius R of circle 2 is next drawn through P therein, as shown in Fig. 13, and on it a` point X is so located that the distance P-X' will equal that of P-X in Fig. 12. Obviously this point X so located will be one in the circumference of the desired inner roll 4, and the final step is then to locate the center of that roll. This can be done by drawing a perpendicular line from the middle point Y of cord 0--X' intersecting the horizontal diameter O Z of circle 2, and such point of intersection c' will be the center of the desired roll circle 4. Consequently the distance O-c' will be the radius r' of such roll, and as previously stated this radius will be approximately 5 inches and therefore a roll of 10 inches diameter cooperating with a ring of 20 inches internal diameter will reproduce substantially the same horn angle as exists in the smaller machine with the 6 inch roll and 9 inch ring.

'I'he possibilities as to-novel and unforeseen results obtained with the enormous pressures per minute unit of surface area of relatively thin ribbons of material which are obtainable in the use of my invention have opened up a whole new field of investigation. i l

So far as I can find the most costly type of reciprocating platen press now on the market can develop a pressure4 of only 2000 lbs. per square inch, and as these presses are composed of so many parts which have to be adjusted before each operation thereof and so much careful manipulation has to be exercised in charging and discharging the press, about an hour's time is consumed in each complete cycle of its`use. In the only type of roll press ever before used commercially, i. e., the ordinary type in which the materlal passes between two oppositely disposed cylindrical rolls, such material will not be"'drawn between the opposing convex roll surfaces after the pressures applied by them equal or exceed a few hundred pounds per lineal inch of the roll faces. As contradistinguished froml such prior apparatus, a press made according to my invention is practically continuous in operation and no part of the material slips back after being grasped between ,the approaching pressure surfaces no matter how great the pressure per unit of area, or per lineal inch of roll face, may be. Furthermore the zone of pressure is narrow circumferentially of the roll and ring and only a relatively thin layer of material of uniform thickness will be fed to that zone when the feed is properly adjusted. Consequently the total pressure per lineal inch applied to the roll is exerted on less than a square inch of surface area of such layer of material. The pressure along each transverse line of the surface of the ingoing ribbon of material increases, as it moves upward, from zero to the maximum attained when passing through the plane in which the axes of the roll and the ring both lie. Consequently, if a pressure of say 9000 lbs. per lineal inch of roll surface be applied of the layer of material as it passes through said plane. There is, obviously, no limit to the roll pressure that can be employed, except the strength of the materials used, and I contemplate the use of special alloy steels which, when casehardened, withstand a pressure of 12,000 lbs. per lineal inch. The hydraulic pressure producing apparatus will, however, be adjustable so that the mill -can vbe operated under any lower pressure found in practice to be sufficient when working on any particular material. Whenever these high pressures are employed the roll 4 is thereby thrust toward the inner surface of ring 2 with such force that they, together with any thin stratum of highly compressed material between their surfaces, form a liquid-tight seal along the mathematical line which would represent surface contact if no foreign material were between. This liquid-tight seal lprevents any slimy, liquid material, like a sewage sludge passing said line at all. Consequently in such case the adjacent surfaces of roll and ring would -pass upward from the line of contact between them clean and dry, all such slimy material having been rolled backward and downward from the lower border of the zone of high pressure.

Having described my invention, I claim:

1. A mechanical dehydrating apparatus, comprising an imperforate revolvable hollow cylinder having an annularly smooth inner surface, an imperforate revolvab-le roller of somewhat less diameter than the internal diameter of said cylthe .axis of the cylinder and the lowest point in its inner surface, a roller bearing upon the outer surface of said cylinder substantially in the plane of said axes and throughout the major portion of the width of contact of said pressing surfaces, means for forcing said rollers toward each other with great but yielding pressure, and means for positively rotating one of said revolvable members in sucha direction that material vto be dehydrated may be fed into the lower portion of the hollow-cylinder.

2. An apparatus as dened in claim 1 in which the diameter of the outer roller is suflciently larger than the diameter of the inner roller to have the same peripheral speed as the outer surface of the ring when rotated at the same angular speed as the inner roller, and means for positively rotating said inner and outer rollers at the same angular speed.

' 3. A mechanical dehydrating apparatus, comprising an imperforate revolvable hollow cylinder having an annularly smooth inner surface and a Asubstantially horizontal axis, an imperforate revolvable roller, of somewhat less external diameter than the internal diameter of said cylinder but at least equal to the radius of the cylinder, and having an annularly smooth outer surface and a substantially horizontal axis in substantially the same horizontal plane as the axis of said cylinder, said roller being positioned within said cylinder and always in contact with the inner surface thereof except when material is being pressed therebetween, the line of contact of the roller and cylinder being substan tially in the plane containing the axes of the roller'v and cylinder, a roller bearing upon the outer surface of said cylinder substantially in the plane of said axes throughout the major portion of the width of contact of said pressing surfaces, means for forcing said rollers toward each other with great butyielding pressure,and means for positively rotating one of said revolvable members in suchv a direction that material to be dehydrated may be fed into the lower portion of the hollow cylinder.v I

4. An apparatus as defined in claim 1 in which the outer roller is on a shaft carried in xed bearings and the inner roller is on a shaft movable toward and fromthe shaft of said outer roller.

5. A mechanical dehydrating apparatus, cornprising an. imperforate revolvable hollow cylinder having an annularly smooth inner surface and a substantially horizontal axis, an imperforate revolvable roller, of somewhat less external diameter than the internal `diameter of said cylinder but at least equal to the radius of the ,cylinder and having an annularly smooth outer surface and a substantially horizontal axis in substantially the same horizontal plane as the axis of said cylinder, said roller being positioned within said cylinder and always in contact with the inner surface thereof except when material is being passed therebetween, the line of contact of the roller andthe cylinder being substantially in the plane containing the axes of the roller and cylinder, means for forcing said surfaces toward each other with great but yielding pressure comprising a second roller having its surface in contact with the outer periphery of the cylinder throughout substantially the entire width of contact of said pressing surfaces, the axis of one of said rollers being movable substantially horizontally toward and from said cylinder, and means for positively rotating one of said revolvable members Iin such a direction that material to be dehydrated may be fed into the lower portion of the hollow cylinder.

6. An apparatus as dened in claim 5 in which the axis of the other of said rollers is in fixed bearings, and said axes are in substantially the same horizontal plane.

7. A mechanical dehydrating apparatus, comprlsing an imperforate, freely revolvable hollow cylinder having an annularly smooth inner sur- Iface and a substantially horizontal axis, an imperforate revolvable roller, of somewhat less external diameter than the internal diameter of said cylinder but at least equal to the radius of the cylinder, and having an annularly smooth outer surface and a substantially horizontal axis in substantially the same horizontal plane as the axis of said cylinder, said roller being positioned within said cylinder and always in contact with the inner surface thereof except when material is being pressed therebetween to provide pressing surfaces Within said cylinder, the line of contact of the roller and cylinder being substantially in the plane containing the axes of the roller and cylinder, a roller bearing upon the outer surface of said cylinder substantially in the plane o! said axes and throughout the major portion of the width of contact of said pressing surfaces, means actuated substantially in said plane for forcing said rollers toward each other with great but yielding pressure,l and means for positively rotating said inner roller in such a direction that material to be dehydrated may be fed into the lower portion of the hollow cylinder.

8. An apparatus as deilned in claim 7 in which the diameter of the outer roller is sufilciently larger than the diameter of the inner roller to have the same peripheral speed as the outer surface of the ring when rotated at the same angular speed as the inner roller, and means for positively rotating said inner and outer rollers at the same angular speed.

9. An apparatus as deilned in claim 1 in which the diameter of the roller is one-half to twolthirds the diameter of the cylinder.

EARLEF. ALLEN.

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