US2220104A

US2220104A - Pulverizer

Info

Publication number: US2220104A
Application number: US759608A
Authority: US
Inventors: Lewis W Heller
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1934-12-29
Filing date: 1934-12-29
Publication date: 1940-11-05
Anticipated expiration: 1957-11-05

Description

2 Sheets-Sheet l Nov. 5, 1940. l.. w. Hl-:LLER

PULVERIZER' Filed Dec. 29, 1934 Nov. 5, 1940..

1 w. HELLER 2,220,104

PULVERIZER Filed Dec. 29, 1934 2 Shets-Sheet 2 INVENTOR Yeu/s W He//er- @Tam v ATTORNEIYy Patented Nov. 5, 1940 PULVERIZEB Lewis W. Heller, New York, N. Y., assignor to The `liaboock Wilcox Company, Newark, N. J a

corporation of New Jersey 4 Application-December zo, im, stringo. 'uam y 19 Claims.

The present invention relates to the construction and operation oi pulverlzers and more particularly, to pulverizers involving cooperating resiliently loaded rolling grinding elements and 6 grinding rings and a selective discharge ofthe pulver-ized material by a gaseous earlier medium passed through the pulverizer in a ilow path generally counter to the now of material.

In pulverizers of the character described inf i cluding two or more superposed circular rows of rolling grinding elements, such as metallic balls, one of the main problems is the proper distribution of the material undergoing pulverization between the rows in order to provide the most e!- lIi fective grinding conditions and distribution of the wear on the grinding parts. As the material usually passes too rapidly through the upper grinding stage, the ilow of material has been heretofore controlled by damming or restricting the material flow from the upper grinding stage by means of screens, grids, dams or orifices. Such devices have not proved wholly satisfactory i'or the purpose as they either cause a quantity of material to be retained in the pulverizer on shutting down or have their regulating eii'ect continuously aiiected by wear and deterioration in use.

In accordance with my present invention, such objectionable characteristics of prior control devices are avoided by eiiecting the desired regulation by controlling the velocity of the carrier medium at one or more critical points in the material iiow path by means of va device or devices subjected to little or no wear in operation in conjunction with an improved material now permitting the centrifugal effect of the rotating grinding parts to be most advantageously utilized. I

A main object of my invention is the provision of a pulverizer having an improved path of ilow of the material undergoing pulverization relative to the gaseous carrier medium.

A further object is the provision of a pulverizer having simple and effective means. for regulating 'the distribution of the material undergoing pulverization therein and better distributing the wear on the grinding partsl and thereby increasing the flneness of the pulverized material discharged and the pulverizer capacity.

I0 'I'he various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and speciiic objects attained by its use,

reference should .be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Oi' the drawings: i Fig. 1 is a sectional elevation of one i'orm of pulverizer constructed in accordance with my invention; and I Fig. 2'is a view similar to Fig. 1 oi' a modified lo construction. The pulverizer illustrated in Fig. 1 comprises a y sectional casing I0 oi circular cross-section having an outlet II in the .top thereof for the discharge of pulverized material and enclosing 15 upper, intermediate and lower vertically spaced horizontally arranged metallic grinding rings I2, I3 and I4, respectively. The lower ring I4 is secured to a bell-shaped yoke Mb mounted on a vertical drive shaft I5 arranged axially oi.' the grinding rings and shaped to support a circular row of metallic grinding balls I6. 'Ihe intermediate ring i3 is supported on the balls I8 and held in a non-rotary iloating position relative to the casing by one or more lugs I 1 positioned between pairs oi' plates Il. An upper circular row of u grinding balls i9 rts on the ring I3 and in turn) supports the upper ring I2, which has a floating drive connection with the drive shaft I5 through a drive yoke 2li having one or more lugs 2| positioned between corresponding pairs of plates n.

22 on the upper ring. A grinding pressure is ad- Justably applied to the upper row of balls by means of a circular series of coiled springs 23 positioned between the top of the upper ring I2 and corresponding arcuately spaced interconnected posts 24 held on the end of the drive shaft,

as shown. The upper row of balls cooperates with the upper and intermediate grinding rings to form an upper grinding stage receiving material to be pulverized at the outer side of the row of 40 balls I9 from a feed pipe 25 and discharging pulv verized material at the inner side of the row of balls. 'I'he pulverized material from the-upper stage drops past the inner side of the intermediate ring to the inner side of the lower row of balls 5 I8, which cooperate with the intermediate and lower rings to form a lower grinding stage having an outward flow of material therethrough.

The lower section of the casing I0 is enlarged at its lower end to form an annular box 30 hav- 5 ing an inlet 3| for a suitable gaseous carrier medium, such as preheated air. The pulverizer is constructed to provide a ow of air in a substantially annular stream upwardly through the casing to the outlet II with successive contacts with the stream of material undergoing pulverization. In the construction shown, the air enters below and at the outer side of the lower grinding stage through a variable annular throatl 32 formed between the outer side oi the grinding ring Il and a downwardly tapering substantially conical baie 33 adjustably supported on the casing I0 by brackets 34. The annular stream oi' air passes upwardly through the throat 32 at a sunlciently m high velocity to sweep up the pulverized material passing over the edge of the lower grinding ring. After leaving the throat 32. the materialladen air expands in the space thereabove, causing any oversize particles to drop out and either 1g return to the grinding surface oi the lower ring I4 or restrict the air flow through the throat.

sumciently to cause an increase in air velocity sumcient to carry them away.` l A The material-laden air flows inwardly through u a series of inwardly inclined ports 38 formed in the intermediate ring I3 yand extending from the outer side oi that ring to a second expansion space at the inner side oi the ring I3 wherein the air stream changes direction, causing any overu size material in suspension to drop out oi.' the air stream and return to the inner side -oi the row of balls I8. The material-laden air then passes upwardly in an annular stream through the stream oi material descending from the upper to the lower vgrinding stage, scavenging the descending material to separate particles of the desired ilneness.

The velocity of the air stream passing upwardly at the inner side of the ring I3 is advantageously regulated to control the interstage ilow of material. The meanse'mployed for this purpose consists of a cone member 38 surrounding the drive shaft I8 and having a downwardly ilaring upper portion 38a, the lower end oi' which is arranged adjacent to the inner side of the ring I3 to provide a narrow annular throat 38 therebetween, and a reduced cylindrical lower portion 38b fitting over and sealing the joint between the drive yoke I4 and the drive shaft. The cone 38 is adjustable axially of the drive shaft to vary the locationV oi the lower end of the portion 38* relative to the ring I3 and thereby the eiiective ilow area of fthe throat 38, by means oi' threaded rods 31 mounted in the drive yoke 20. The air stream after passing through the throat 38 passes upwardly mainly past the inner side oi the balls I8 and loutwardly through the openings between the spaced posts 2l rto the outlet II. .Any oversize material separatingby gravity from the air stream in the upper casing section will be returned to the upper grinding zone for further grinding. An annular conical baffle 39 is mounted on the ring I3 with its upper end substantially in contact with the casing to direct the material into the ball row I9 and prevent the air stream short-circuiting the upper grinding stage.`

In operation, material delivered by the inlet pipe 25 and material separated in the upper part of the casing passes from the outer side ot the row oi balls I8 substantially radially inwardly and is dischargedat the inner side of the ball row. The passage ot the material through the upper grinding stage is partly opposed by the centrifugal effect of the rotating balls and ring I2 and the velocity of the air stream passing the inner side o! the balls I8, the air velocity being controlled at the throat 38 to retain the material in the upper grinding stage a predetermined time and thereby effect the desired grinding action in the upper stage. 'Ihe location of the throat 38 at terial pulverized'in the upper stage drops through the uprising air stream which picks up a large proportion of the descending fine material, the remaining material being delivered to the inner side of thellower row of balls I8. The material passes substantially radially outwardly through the lower row oi balls, its passage being accelerated by the centrifugal eiiect of the rotating balls and lower ring and restricted bythe uprising outer edge oi the lower ring. The material leaving the lower grinding stage at the outer side oi the row of balls I8 is swept up by the ascending high velocity air stream. The material-laden air then passes upwardly at the outer side oi the balls I8 and through the ports 3l as' previously described. The baille 33 may be thus adjusted toinsure an air velocity sumcient to sweep up all oi the material discharged i'rom the lower grinding zone. while the cone 38 is adjusted to control the discharge o! material from the upper grinding stage and thereby the flow o! material interstage.

With the ilow control provisions constructed and arranged as described it is practical to vary the air ilow through the pulverizer tor diierent rates of pulverination or moisture content of the material without choking the pulverizer, since the air velocity at the critical locations can be eilectively adjusted. Ii the quantity oi air to be passed becomes so great due' to the requirements for drying or transportation that the velocities and .pressure drops through the ports 38 and throat 38 tend to become excessive, valve controlled openings maybe provided inthe baille 38 to permit a portion ot the air to by-pass .the ports 35. Under certain conditions vwhen changes in the total air quantity passed are desirable, automatic means can be provided for actuating one or both of the throat area adjusting means in accordance with' changes in the quantity of air supplied. The foregoing construction provides a particularly eiective control oi' the amount of pulverization in the several stages, and the delivery ci material oi the desired degree oi ilneness to the mill outlet.

Where the ilow restricting provisionsused heretoiore have been adjustable, the making oi such adjustments usually required the shutting down of the pulverizer. In Fig. 2 I have illustrated a modified construction wherein the regulating devices ior both the throats 32 and 38 are externally adjustable without requiring any change in the pulverizer operation. In this modiilcation, the upper and lower grinding rings I2- and .Ih respectively are non-rotary, while the intermediate ring I3* has a floating drive connection with the drive shaft Il* through a drive yoke l and cooperating lugs and plates 4I and 42 respectively. The air and material ilow paths are similar to those previously described. Regulation of the throat 38 is eiiected by a cone member 50 having an upper downwardly flaring section I0 and a lower reduced sleeve section 88h surrounding and slidable on an upstanding sealing flange 44 carried by the yoke l0. The cone 50 is carried extending upwardly through the top of the casing vbetween the outlets II. The projecting end n aaaaioa of the rod is held by a nut 53, which controls the position of the cone and thereby the eflective 'area of the throat 38. In view of the tilting of the rotary intermediate ring I3* in operation, the portion of the casing adjacent the upper end of the conical baille 39a on the ring is curved outwardly at 43 parallel to the arc in which the adjacent edge Iof the ring will move on tilting of the ring. The same clearance is thus maintained between the ring and casing at all times permitting a small quantity of air to flow therethrough in normal operation. e I

While I have illustrated and described my invention, as applied to a multi-stage pulverizer, those skilled in the art will understand that certain features of the invention are similarly adapted for use in single stage pulverizers and that changes may be made inthe form of the apparatus disclosed without departing from the spirit of the invention covered by my claims. In my claims, the term air is used generically to cover any gaseous carrier medium suitable for removing pulverized material inthe manner described.

I claim: i

l. A pulverizer comprising a casing having an outlet for pulverized material in the upper part thereof and enclosing vertically spaced upper, intermediateand lower grinding rings, upper and lower circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings respectively and cooperating therewith to form an upper grinding stage having a flowof material therethrough in one direction and a free discharge of material therefrom and a lower grinding stage receiving material from said upper stage and having a iiow of material therethrough in the opposite direction, means for delivering material to be pulverized to the inlet side of said upper row of elements, and means for directing an annular stream of air upwardly through said casing past the discharge side of said lower row of elements and then past the discharge side of said upper row of elements, said air flow directing means including baffle means spaced from thedischarge side of said intermediate grinding ring and arranged relative to said intermediate grinding ring to dene opposite sides of an annular air passage of substantially reduced ilow area along the discharge side of sai'd intermediate grinding ring and thereby provide an increased air velocity at the discharge side of said upper row of elements.

2. A pulverizer comprising a casing having an outlet for pulverized material in the upper part thereof and enclosing verticallyspacedupper, intermediate and lower grinding rings, upper and lower circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings respectively and cooperating therewith to form an upper grinding stage having a iiow of material therethrough in one direction and a free discharge of material therefrom and a lower grinding stage receiving material from said upper stage and having a flow of material therethrough in the opposite direction, drive means arranged to rotate said intermediate grinding ring-relative to said upper and lower grinding rings, means for delivering material to be pulverized to the inlet side of said 'upper row of elements, and means for directing an annular stream of air upwardly through said casing past the discharge side of said lower row of elements and then past the discharge side of said upper row of elements, said air flow directing l 3 means at the discharge side of said intermediate grinding ring consisting of annular baille means extending along the discharge side of said intermediate grinding ring and spaced radially therefrom to form an annular air passage of substantially reduced flow area along thedischarge side of said intermediate grinding ring to thereby provide an increased velocity ofair iiow upwardly past the discharge side of said intermediate grinding ring and upper row of elements.

3. A pulverizer comprising a casing having an outlet for pulverized material in the upper part thereof and enclosing vertically spaced upper, intermediate and lower grinding rings, upper and lower circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings respectively and cooperating therewith to form an upper grinding stage having a flow of material therethrough in one direction and a lower grinding stage receiving material from said upper stage and having a flow of material therethrough in the opposite direction, means-for delivering material to be pulverized to the inlet side of said upper row of elements. means for directing an annular stream of air upwardly through said casing past the discharge side of said lower row of elements and then past the discharge side of said upper row of elements, regulable means at the discharge side of said lower row of elements for controlling the air velocity past said lower row of elements, and regulable means at the discharge side of said upper row of elements for controlling the air velocity past said upper row of elements.

4. A pulverizer comprising a 'casing enclosing a plurality of vertically spaced horizontally arranged grinding rings, an upper circular row of rolling grinding elements positioned between a pair of said grinding rings, means for supplying material to be pulverized to the outer side 4of said upper row of elements, a lower circular row of rolling grinding elements positioned between a pair of saidgrinding rings and yarranged to receive ma-` terial from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof, drive means arranged to effect relative rotation between vertically adjacent grinding rings, means for directing a stream of air past the4 ranged grinding rings, an upper circular row of rolling grinding elements positioned between a pair of saidgrinding rings, means for supplying material to be pulverized to the outer side of said upper row of elements, a lower circular row of rolling grinding elements positioned between a pair of said grinding rings and arranged to receive material from said upper row of elements atv the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof, drive means arranged to effect relative rotation between vertically adjacent grinding rings, means for directing a stream of air past the outer side of said lower row of elements and then past the inner side of said upper row of elements, regulable means at the outer side of said lower row of elements for controlling the air velocity past said lower row of elements, and regulable means at the inner side of said upper row of elementsgor controlling the air velocity past said upper rowf elements.

' 6. A pulverizer comprising a casing enclosing vertically spaced'horizontally arranged rotary upper and lower grinding rings. a horizontally ar- .ranged non-rotary grinding ring intermediate said upper and lower grinding rings, an upper circular row of rolling grinding elements positioned between said upper and intermediate. grinding rings, means for supplying material to be pulverized to the outer side of said upper row of ele-` ments, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings and arrangedto receive material from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof, a drive mechanism arranged to effect rotation of said upper and lower grinding rings, said intermediate grinding ring having ports for material-laden air extending transversely thereof, means for directing a stream of air past the outer side of said lower row of elements, through said ports and past the inner side of said upper row of elements, and regulable means at the inner side of said upper-row of elements for controlling the air velocity past said upperrow of elements.

. '7. A pulverizer comprising a casing enclosing vertically spaced horizontally arranged rotary upper and lower grinding rings, a horizontally arranged non-rotary grinding ring intermediate said upper and lower grinding rings, an upper circular row of rolling grinding elements positioned between said upper and intermediate grinding rings, meansfor supplying material to be pulverized to the outer side of said upperY row of elements, a lower circularrow of rolling grinding elements positioned between said intermediate and lower grinding rings and arranged to receive material from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof, a drive mechanism arranged to eii'ect rotation of said upper and lower grinding rings, said intermediate grinding ring having ports for material-laden air extending transversely thereof, means for directing a stream of air past the outer side of said lower row of elements. through said ports and past the inner side of said upper row of elements, regulable means at the outer side of said lower row of elements for controlling the air velocity past said lower row of elements, and regulable means at the inner side of said upper row of elements for controlling the air velocity past said upper row of elements.

8. A pulverizer comprising a casing enclosing verticailyspaced horizontally arranged rotary upper and lower grinding rings, a horizontally arranged non-rotary grinding ring intermediate said upper and lower grinding rings, an upper circular row of rolling grinding elements positioned between said upper and intermediate grinding rings, means for supplying material to be pulverized to the outer side of said upper row of elements, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings and arranged to receive material from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof,

a drive mechanism arranged to eii'ect rotation of said upper and lower grinding rings, said intermediate grinding ring having ports for materialladen air extending transversely thereof, means fordirecting a stream of air past the outer side y of said lower row of elements, through said ports and past the inner side of said upper row of elements, and a cone member adjustably mounted on said drive mechanism at the inner side of said upper row of elements for controlling the air velocity past said upper row of elements.

9. A pulverizer comprising a casing enclosing vertically spaced horizontally arranged rotary upper and lower grinding rings, a horizontally arranged non-rotary grinding ring intermediate said upper and lower grinding rings, an upper circular row of rolling grinding elements positioned between said upper and intermediate grinding rings,

means for supplyingmaterial to be pulverized to the outer side of said upper r'ow of elements, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings and arranged to receivematerial from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof, a drive mechanism arranged td effect rotation of said upper and lower grinding rings, said intermediate grinding ring having ports for materialupper and lower grinding rings, a circular row `of rolling grinding elements positioned between said grinding rings, means'for supplying material to be pulverized to the inner side of said row of elements, drive means arranged to effect relative rotation between said grinding rings, and means for directing a stream of air upwardly past the outer side of said lower grinding ring and row of elements, said air directing means including an annular baille mounted on said casing at the outer side of said elements and cooperating with the outer side of said lower grinding ring to dene therebetween an annular air passage of substantially reduced flow area along the -outer side of said lower grinding'ring and thereby provide an increased air velocity at the outer side of said row of elements.

11. A pulverizer comprising a casing enclosing upper and lower grinding rings, a circular row of rolling grinding elements positioned between said grinding rings, means for supplying material to be pulverized to the inner side of said row of elements, drive means arranged to effect relative rotation between said grinding rings, said upper grinding ring having ports for material-laden air extending transversely thereof, means for directing a stream of air upwardly past the outer side of said row of elements and then through said ports, and regulable baille means at the outer side of and below said row of elements for controlling the air velocity past said row of elements.

12. A pulverizer comprising a. casing enclosing tation between said grinding rings, said upper 1| grinding ring having ports for material-laden air 1 extending-transversely thereof, means for directsitloned between said upper and intermediate grinding rings, means for supplying material Vto be pulverized to the outer side of said upper row of elements, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings and arranged to receive material from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof, a drive mechanism arranged to effect rotation of s aid intermediate grinding ring, means for directing a. stream of air past the outer side of said lower row of elements and subsequently adjacent to the inner side of said upper row of elements. and regulable baffle means adjacent to the inner side of said upper row of elements for (ill varying the velocity of said air stream.

14. A pulverizer comprising a casing enclosing vertically spaced horizontally arranged non-rotary upper and lower grinding rings. a horizontally arranged rotary grinding ring intermediate said upper and lower grinding rings. anupper circular row of rolling grinding elements positioned between said upper and intermediate grinding rings. means for supplying material to be pulverized to .the outer side of said upper row of elements, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings and arranged to receive material from said upper row of elements at the inner side of said lower row of elements and to discharge material pulverized thereby at the outer side thereof. a drive mechanism arranged to effect rotation of said intermediate grinding ring. said intermediate grinding `ring having ports for material-laden air extending transversely thereof.v means for directing a stream of air past the outer side of said lower row of elements through said ports and subsequently past the inner side of said upper row of elements, means at the inner side of said upper row of elements for controlling theair velocity past said upper row of elements, and means for externally operating saidlast mentioned means.

15. A pulverizer comprising a casing enclosing a plurality of verticallyspaced horizontally ar-* ranged grinding rings comprising upper, intermediate and lower grinding rings, an upper circular row of rolling grinding elements positioned between said upper and intermediate grinding rings, means lfor supplying material to be pulverized to the outer side of said upper row of elements, a lower circular row of rolling grinding elements positioned between vsaid intermediate and lower grinding rings and arrangedto receive material at the inner side thereof from said upper row of elements through a substantially annular passage'at the inner side of said intermediate grinding ring and to discharge material pulverized thereby at the outer side of said lower row of elements, drive means arranged to eii'ect lrelative Arotation between said upper and lower grindingrings and said intermediate grinding ring, and regulable means at the inner side o f said intermediate grinding ring for controlling the radial width of said passage.

16. A pulverizer comprisinga casing enclosing a plurality of vertically spaced horizontally arranged grinding rings, an upper circular row of rolling grinding elements positioned between a pair of said grinding rings, means for supplying material to be pulverized to the outer side of ,said upper row of elements. a lower circular row of rolling grinding elements positioned between e side of said lower row of elements for controlling the discharge of material from said lower row of elements, and regulable means at the inner side of said upper row of elements for controlling the passage of material from said upper row to said lowerrow of elements.

' 17. A pulverizer comprising a casing enclosing a lower rotary grinding ring. a circular row of rolling grinding elements supported on said lower grinding ring, a non-rotary upper grinding ring supported on said grinding elements, said lower grinding ring having a material discharge edge at the outer side of said grinding elements, means for rotating said lowergrinding ring, means for delivering material to be pulverized to the inner side of said row of grinding elements, and means for directing a stream of air upwardly past the outer side of fsaid lower grinding ring to sweep up pulverized material discharging therefrom including means cooperating with the outer periphery of said lower grinding ring to define therebetween a restricted throat passage below the level of the discharge edge of said lower grinding ring.

18. A pulverizer comprising a casing enclosing a lower grinding ring, a circular row of rolling grinding elements supported on said lower grinding ring, an upper grinding ring supported on said grinding elements, said lower grinding ring having a material discharge edge at a level below the centers ofI said grinding elements. drive means arranged to effect relative rotation between said grinding rings, means for delivering material to be pulverized to the inner side of said row of grinding elements, and means for directing an annular stream of air upwardly past the outer side of said lower grinding ring to sweep up pulverized material discharging therefrom including means cooperating with the outer periphery of said lower .grinding ring to deiine therebetween an annular' passage having a re- 5 therefrom including an annular plate shaped relative to and cooperating with the outer penpnery of im lower grinding ring to denne therebetween an annular passage having a restricted throat below the level of` the discharge.

edge of said lower grinding ring. A

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