US2562753A - Anvil grinder - Google Patents

Description

July 31, 1951 v c. TROST ANVIL GRINDER Filed May 24, 1948 I JNVENTOR. CONRAD TROST M Mu ATTORNEY Patented July 31, 1951 ATENT OFFICE ANVIL GRINDER Conrad Tros t, Moorestown,,N. J assignor to The Micronizer Company, New York, N. Y., a corporation ofiDelawa're Application May'24, 1948, Serial No..28-,850

*"r cam l (01. 241.59)

Thisinvention. relates to animproveme'nt in reentrant, circulatory type pulyerizing, mill,. partifcularly one which is adaptedlto effect reduction in particle size. of amorphous materials. g It. has been. learned, through careful observation of mills of the general. type disclosed by the Andrews Patent No..2',032,827 that more efiective pul'verization. is produced by the direct cutting action of thelgrinding' fluid being injected'into a, grinding. chamber than is produced by the interaction of particles of' the material, being subdividedupon each other or upon the walls of, said chamber 5 a It has, however, been iurther learned thatthe turbulence, which ofnecessity accompanies an increase in the rate offintro'duction of the grind;- ing fluid into, the grinding chamber and, within limits, improves the grinding action, also creates a. detrimental phenomena, referred toy in the art as kickbacks, whichjior practical purposes in many cases counteracts. the gains realized as a result of creatingsu'ch turbulence by causing undesirably oversize particles to appear in. the fi'nished' product. j It is, therefore, desirable to introduce suitable means within the radially outermost portion of said grinding chamber, where the larger particles being processed at any given "time tend to collect as a result of centrifugal force, whereby the'pulveriZ-ingaction upon such relatively large part1; cles' will be increased while undesirable turbu lence, and the detrimental effects resulting therefrom, are'held toa minimum. I It has been observed that the'reentrant, circu latory type" pulveriaing mill, as formerly constructed and as illustrated; for example in the aforesaid Andrews Patent'N'o. 2,032;82-7 i's priamorphous and/or loss frangible'type materials effectively, there is" a wide range of applications for mills of this type in such fields as the prepared and/or powdered foods industries. Powdered milk, cocoa, stock feed and instant coffee are representative examples of the applicable products of such industries, which are presently powdered by slow, expensive, discontinuous methods such as the ball mill, hammer mill, or other mechanical means. a I

Accordingly, a primary object of myinvention' is to provide means, whereby the pulverizing action upon relatively large particles of material being processed in a reentrant, circulatory type pulverizing mill will be substantially increased.

A. further. object. of my invention isto provide 2 I means, asaforesaid, which will effect an increase in efiective exposure of said relatively large par, ticles of material to-the attrition of the grinding fluid.- A further object of this invention isto. provide means, as-aforesaid, which will be inexpensiueto construct and readily adaptable. to. the, typeoi circulatory pulveri'zing. mills presently in use. 7

A further object of. theinvention. is to provide. means, as aforesaid, which. will accomplish-the aforesaid. desired results. without proportionally increasing undesirable efi'ects, such asturbulence and theresulting kickbacks? A further object of the invention is to provide, a mill of the aforesaid type which will bdad'aptable to, the comminution of soft and amorphous, or non-frangible, materials, especiallyso; that it will be possible to impart: speed, cleanliness and uniformity of particles size: into the grinding of food products. I

Other objects and purposes of thisinvention' will become apparent to persons familiar with this type of equipment upon referring to the accompanying drawings and upon readingthe following specification.

In order to meet the objects and purposes heretofore set forth, as well as others incidental thereto and associated therewith, I have placed a plurality of restrictors, wedge-shapedinmy preferred embodiment, within the grinding chamber of a conventional type, circulatory pulverizi'ng mill such as is disclosed in Andrews Patent No.

2,032,827. Said restrictors are placed within the radially outer portion of said grindingchamber; each adjacent to a jet, preferably so thatthe stream of energizing fluid emitted from said jets will impinge upon an impact surface of said rte-- strictc'r near the downstream end thereof-andat least so that the outer portion ofthe circulating fluid and larger particles contained therein will" be diverted by said: restrictors towardsthepe ripheralwall of thechamber; I Said restrictors are preferably of longer: dimerr=- sion in the direction of circulation-thantransversely thereto andnormally'contact both the top and bottom walls of the said pulverizing mill.

*ltiaterial' to be pulverize'dis introduced intothe: grinding chamber of said mill through suitable conventionalmeans and isengagedand circa: lated by grinding fluid emitted: from: a plurality of tangentially placed grinding jets: 'Thelarger particles are thrown to'the outer periphery of circulation as a result of centrifugal force. In so doing, said, larger particles areforcedto pass between said restrictors and the inside surface of the outer side wall. of said grinding chamberv near the point where said jets are mounted, in

said side wall. The presence of the restrictors creates, with the adjacent side wall of the grinding chamber a confined, preferably venturi, =passageway, wherein and. whereby the material as it passes therethrough is made to approach the jets more closely. ,The effectiveness of the cutting action of said jets upon the particles is thereby substantially increased.

Furthermore, said cutting stream will deflect a considerable quantity of said large particles against said restrictors, whereupon the resultant impact will tend to abrade at least some of said large particles, although this appears to be of relatively minor importance.

For an illustration of one preferred embodiment of the invention reference is made to the drawings in which:

Figure 1 is a top view of the pulverizing mill takenin section along the line I-I.of Figure 2 in order to expose the grinding anvils or restrictors.

Figure 2 is a side, centrally sectioned view of said pulverizing mill taken along the line II--II of Figure 1.

Figure 3 is a view similar to that of Figure 1 showing one modification of the invention.

Figure 4 is a view similar to that of Figure 1 showing a further modification of the invention.

The reentrant circulatory type pulverizing mill illustrated in Figures 1 and 2 may be conventional both in shape and in construction, such as disclosed in the Andrews Patent No. 2,032,827. So constructed, and here shown as an illustrative example, the grinding mill shell I is comprised of a circular top plate II, a circular bottom plate 12 and a cylindrical side wall I 3, which is secured, as by. welding, at its upper edge to the periphery of said top plate I I and at its lower edge to the periphery of said bottom plate l2.

Said plates and side wall may be constructed of any suitable material but are preferably of steel plate.

The bottom plate I2 is provided with a sufllcient opening I! for sealed reception of, and securement to, the upper portion of the cylindrical section 14 of the cyclone chamber l5, which is concentric in its entirety with the said cylindrical side wall l3, and may be entirely conventional. The upper extremity of said cyclone l5 approaches but does not contact, the upper plate ll of the grinding chamber iii. A tapered, conical section I6 is secured, as by welding, to that extremity of said cylindrical section M which is below and remote from engagement with said grinding mill bottom plate l2.

Radially disposed within said side wall 13 and coaxial therewith, is a cylindrical partitioning wall 20 which provides the inner wall of a relatively narrow energizing fluid header 2i as well as the outer wall of a relatively large grinding chamber 22. Said wall In is pierced by a plurality of jet openings 23 through which the energizing fluid is emitted under pressure from the header 2|. The longitudinal axes of said openings are tangentially disposed with respect to a theoretical circle within said grinding chamher and concentric therewith, thereby imparting the most desirable motion to said particles and producing the most eificient pulverization of said particles in said stream. Since this positional relationship between said jets and said steam, in the type pulverizing mill herein shown for illustrative purposes, is well known to the art, no further description will be here given.

A circular plate of suitable abrasion resistant material, such as manganese steel, comprises the bed plate 24, which constitutes the floor of said grinding chamber 2'2. Said bed plate 24 is removably secured, as by bolting, to said bottom plate 12 of the grinding mill within the bounds of the cylindrical partitioning wall 20. Said bed plate is preferably, but not necessarily, of heavier gauge material than said bottom plate I2 and is provided with an opening 25, coincident with said opening I! in said bottom plate, for reception of said cylindrical section II of the cyclone chamber ii.

A plulrality of, here four, grinding wedges or restrictors 26 are uniformly spaced about and within the radially outer portion of the said grinding chamber 22, a comparatively short radial distance inward from said partitioning wall, where they bear against and are secured, as by bolting,.to both the top plate Ii and bed plate 24. Said restrictors are advantageously positioned, one adjacent to each jet, so that the fluid emitted from said jets will strike the plane, outer surface of said restrictors at whatever angle may be desired. As illustrated in Figure 1, the said restrictors have a long, narrow, horizontal cross-section, whose lengthwise axis is subtially perpendicular at the midpoint thereof to the radius of said grinding chamber 22 passing therethrough, and substantially tangent at said midpoint to the stream of particles circulating through said grinding chamber.

It will be understood, however, that the jets 23 need not all be associated with adjacent restrictors 26. It may develop in specific cases that the resrictors are best placed adjacent to alternate jets, as shown in Figure 3, or in some other suitable arrangement, depending upon the quantity of jets and restrictors required, it will also be understood that the distance of said restrictors from said partitioning wall 20 may be varied to suit the requirements, as shown in Figure 4, without departing from the scope of the invention. 7

The said restrictor 26 is preferably tapered, from about midway of the extremities thereof to a sharp edge at the upstream end 21 of said restrictor, thereby presenting the appearance of a wedge. The tapering, it should be noted, causes the wedge to form a venturi in cooperation with the side wall of the grinding chamber. The remainder of said restrictor has parallel sides one of which provides said plane striking surface at 28 for said stream of energizing fluid. The end 29 remote from said tapered edge is either squared oil, as shown, or otherwise terminated in any suitable manner, which will preferably reduce to a minimum the turbulence ofrthe gaseous stream.

Other forms of restrictors may be used, as is also illustrated in Figures 3 and 4, wherein the venturi effect is both increased and decreased, respectively, from that incident to the construction of restrictors shown in Figure 1.

The top plate I I of said grinding mill l 0 has an appropriate opening 3! therein for sealed reception of, and securement to a, suitable offtake 32, which is concentric with and somewhat telescoped at its lower end 33 by the upper end 34 of the cylindrical section I! of said cyclone chamber l5. Said offtake 32 may be constructed of any material and in any convenient and conventional form. Inasmuch as the construction of, and cooperative relationship between, the offtake 32, the grinding mill l0, and the cyclone chamber l5 are well known and amply exemplified in the art, such amass 5,1 as. in the said Andrews Patent No. 2,032,827, no further description will herein be devoted. thereto.

In operation, the material to be processed is fed from any suitable source of supply into said grinding chamber 22 through any: conventional means, such as through a hopper and aninjecting nozzle schematically indicated at 3B. Circulation of the relatively large incoming particles comprising said material is effected.- in said grindng chamber 22 in a conventional manner by the-streams of fluid under pressure emitted from said jets 23 in the partitioning wall 20'. In accordance with the physical laws of centrifugal force, said large particles will tend to circulate within the peripheral portion of said grinding chamber.

The presence of the restrictors 26* will force-substantially more of thelarge particles close to the jets than would otherwise so travel, and the'Venturi efiect created by the restrictors 26 and. said partitioning wall 2!] will accelerate the travel of said particles, both features increasing the. grind,- ing action on the particles. As said large particles flow through said venturi 35, they are exposed tothe cutting force of the stream of fluid emitted from said jets but instead of being propelled toward the center of the chamber where some of them may be entrained by the exhausting gas, said particles are deflected" back to the circulatory stream, thereby greatly reducing kickbacks, and increasing attrition of the particles. By reducing the escape of large particles, or kickbacks, and by concentrating thelargeparticles in the region of the jets, thereby increasing the attritionof the particles, the mill output and efficiency are greatly improved over the conventional type pulverizing mill.

The grinding wedges or restrictors 26 may be substantially streamlined for the purpose of reducing to a minimum turbulence and the above described resultant unfavorable efiects thereof.

The means by which and the manner in which the uniformly pulverized, relatively small particles of processed material are entrained by the ex.- hausting gas or energizing fluid, as it moves from said grinding chamber 22 into the cyclone chamber 15, where the product is separated from the gas which is vented through said stack 32, are sufiiciently well known to the art and have no special bearing on this invention, and accordingly speciflcdescription thereof will beomitted.

Although the above mentioned drawingsand description apply to. one particular, preferred embodiment of the invention, it is not my intention, implied or otherwise, toeliminate other variations or modifications which do not depart from the scope of the invention unless specifically stated to the contrary in the hereinafter appended claims.

I claim: 7 1. In means for pulverizing partially comminuted, solid materials, which means includes: a substantially circular grinding chamber having top and bottom plates; means directing a plurality of' grinding fluid jets, under pressure; into said grinding chamber in the same tangential direction with respect to a theoretical circle within said grinding chamber and concentric therewith; means for feeding said partially comminutedmaterial to be pulverized into said grinding chamber, and means centrally located with respect to said grinding chamber, through which is exhausted said grinding fluid and the pulverized material entrained thereby, the improvement comprising: a plurality of elongated restrictors, whose longitudinal axes are substantially tangential to the cirradially-inwardly from the peripheral wall of said grinding chamber, thereby creating a passageway ofd'ecreasing cross-section in the direction of flow of" said grinding fluid between said peripheral wall and said radially outer wall of each of the said restrictors adjacent thereto, whereby the said partially comminuted material, entrained by and circulating with said grinding fluid in the radially outer peripheral portion of said grinding chamber, will be concentrated and accelerated in the-zones of the jets as it passes each of said jets.

2. In means for pulverizing partially comminuted, solid materials, which means includes: a substantially" circular grinding chamber having top and bottom plates; means directing a plurality of. grinding fluid. jets, under pressure, into said grinding chamber in the same tangential direction with respect to a theoretical circle within said grinding chamber and concentric therewith; means for. feeding; said partially comminuted material to be pulverized into said grinding chamber; andmeans'; centrally located with respect: to said grinding chamber, through which are exhausted said grinding fluid and the pulverizedmaterial, entrained thereby, the improvement comprising: an elongated restrictor, whose longitudinal axis. is substantially tangential to the circulatory fiow of. grinding fluid within said grinding chamber, which restrictor extends from the top plate to the bottom plate of said grinding" chamber, is spaced radially inwardly from the peripheral wall of said grinding chamber, and is located adjacent to and in line with each one of the said jets, so that the grinding fluid emitted therefrom will impinge against the radially outer wall. of said, adjacent restrictor, thereby creating a passageway between the said peripheral wall and said restrictor whereby the said partially comminuted material entrained by and circulating with said grinding fluid in the radially outer peripheral portion. of said grinding chamber, will be; brought towards. said jet. and accelerated in the zone. of the jet. 3.-In means for pulverizing partially comminuted, solidmaterials, which means includes: asubstantially circular grinding chamber having top-and bottom plates; means directing a plue ralityof grinding fluid jets, under pressure, into said grinding chamber in-the same tangential direction with respect to a, theoretical circle withinsaid grinding chamber and concentric therewith; means; for feeding, said partially comminuted material tobe pulverized into-said grinding. chamber; and means centrally located with respect to said; grinding; chamber, through. which are exhausted. said grinding, fluid and the pul- Jverized material. entrained; thereby, the improve- 11161117, comprising: an elongatedrestrictor, whose longitudinal axis is substantially tangential to the circulatory flow of grinding fluid within said grinding chamber, which restrictor extends from the top plate to the bottom plate of said grindags'eazsa ing chamber, is spaced radially, inwardly from the peripheral wall of-said grinding chamber, is located adjacent to each one of the said jets and is so shaped that the portion of the radially outer wall of said restrictor, extending upstream with respect to the direction of circulation of the said grinding fluid within said grinding chamber from a point substantially midway between the longitudinal extremities of said restrictor, diverges radially inwardly from the peripheral wall, of said grinding chamber thereby creating the Venturied passageway between said peripheral wall and said radially outer wall of said restrictor'adjacent thereto, whereby the'said partially comminuted material, entrained by and circulating with said grinding fluid in the radially outer peripheral portion of said grinding chamber will be brought toward said jet and accelerated in the region of said jet.-

4. In means for pulverizing partially comminuted, solid materials, which means includes: a substantially circular grinding chamber having top and bottom plates; means directing a plurality of grinding fluid jets under pressure into said grinding chamber in the same tangen tial direction with respect to a theoretical circle within said grinding chamber and concentric therewith; means for feeding said partially comminuted material to be pulverized into said grinding chamber; and means centrally located with respect to said grinding chamber, through which are exhausted said grinding fluid and the pulverized material entrained thereby, the improvement comprising: an elongated restrictor, whose longitudinal axis is substantially tangential to the circulatory flow of grinding fluid within said grinding chamber which restrictor extends from the top plate to the bottom plate of said grinding chamber, is spaced radially inwardly from the ripheral wall of said grinding chamber, is shaped to form a venturi therewith and is located adjacent to and in line with each one of the said jets, so that the grinding fluid emitted therefrom will impinge against the material entrained by the grinding fluid when its speed is increased over that existing in the part of thegrinding chamber unaffected by the venturi but radially co-extensive therewith.

5. In means for pulverizing partially comminuted, solid materials, which means includes: a substantially circular grinding chamber having top and bottom plates; means directing a plurality of grinding fluid jets under pressure into said grinding chamber in the same tangential direction with respect to a theoretical circle within said grinding chamber and concentric therewith; means for feeding said partially comminuted material to be pulverized into said grinding chamber; and means centrally located with respect to said grinding chamber, through which are exhausted said grinding fluid and the pulverized material entrained thereby, the improvement comprising: a plurality of elongated restrictors within said grinding chamber closely adjacent the wall thereof, each havin a longitudinal axis substantially parallel to the circulatory flow of grinding fluid within said grinding chamber and extending from the top plate to the bottom plate of said grinding chamber; the portion of the outward face of each of said restrictors, extending upstream of said grinding fluid, tapered inwardly from the peripheral wall of the grinding chamber for defining a passageway between each of said restrictors and the wall of said grinding chamber progressively decreas ing cross-section in the direction of flow of said grinding fluid; each of said jets directed across said restricted passageway near its point of smallest cross-section and against one of said restrictors whereby the grinding fluid emitted from said jets will impinge against the material entrained by the accelerated grinding fluid transitin said restricted passageway.

6. In means for pulverizing partially comminuted, solid materials, which means includes a substantially circular grinding chamber having top and bottom plates; means directin a plurality of grinding fluid jets, under pressure, into said grinding chamber in the same tangential direction with-respect to a theoretical circle within and concentric with said grinding chamber; means for feeding said partially comminuted material to be pulverized into said grinding chamber, and means centrally located with respect to said grinding chamber, through which is exhausted said grinding fluid and the pulverized material entrained thereby, the improvement comprising: a plurality of elongated restrictors whose longitudinal axes are substantially tangential to the circulatory flow of grinding fluid within the said grinding chamber, extending from the said top plate to the said bottom plate of said grinding chamber, spaced radially inwardly from the peripheral wall of said grinding chamber, and located, one adjacent to and in line with each of said jets, alternate restrictors spaced radially inwardly of the restrictors on the downstream and upstream sides thereof with respect to the direction of circulation of said grinding fluid, said restrictors so shaped that the radially outer wall of each of the said restrictors, extending upstream with, respect to the direction of circulation of said grinding fluid within said grinding chamber from the impingement point of the said adjacent grindin fluid jet upon each of said restrictors, diverges radially inwardly from the peripheral wall of said grinding chamber, thereby creating a passageway of decreasing cross-section in the direction of flow of said grinding fluid between said peripheral wall and said radially outer wall of each of the said resistors adjacent thereto, whereby the said partially comminuted material, entrained by and circulating with said grindin fluid in the radially outer peripheral portion of said grinding chamber, will be concentrated and accelerated in the zones of the jets at it passes each of said jets.

CONRAD TROST.

REFERENCES CITED The following references are of record in the file of this patent:

Y UNITED STATES PATENTS Number Name Date 258,341 Ager May 23, 1882 1,874,150 Anger Aug. 30, 193 2,032,827 Andrews Mar. 3, 1936 2,191,095 I-Iobbie Feb. 20, 1940 2,237,091 Stephanoff Apr. 1, 1941 2,325,080 Stephanofl' July 27, 1943 2,376,747 Andrews May 22, 1945

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