US2071379A

US2071379A - Pulverizer

Info

Publication number: US2071379A
Application number: US390698A
Authority: US
Inventors: Ervin G Bailey; Perry R Cassidy; Ralph M Hardgrove
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1929-09-06
Filing date: 1929-09-06
Publication date: 1937-02-23
Anticipated expiration: 1954-02-23

Description

Feb. 23, 937.

v E. G. BAIL Y ET AL PULNE IZER Original Fild Sept. 6, 1929 5 Sheets-Sheet l VENTORS Feb. 23, 1937. E. G. BAILEY ET AL.

PULVERI Z ER Original Filed Sept. 6, 1929 3 Sheets-Sheet 2 FIG. 3.

4Q @VENTOR u/g/ M W @TTOW Feb. 23, 1937. E. G. BAILEY .ET AL 3 1 PULVERIZER Original Fild Sept. 6, 1929 5 Sheezs-S'neet 3 maww A)? iQFORNEzS UNITED STATE Patented Feb. 23, 1937 PULVERIZER s PATENT OFFICE Newark, N. J., a corporation of New Jersey Application 15 Claims.

The present invention relates to an improved construction of a pulverizer or grinding mill of l by a common rotary grinding ring to form upper and lower grinding stages. The improved pulverizer is especially adapted for grinding coal, but is also adapted for grinding othermaterials.

The general object of our invention is the provision of a pulverizer or grinding mill of the general type described which is especially characterized by its high capacity, high degree of fineness or output, substantially uniform wear of the grinding parts of the several stages, andrelatively low powerconsumption. A further and more specific object is the provision of simple September 6, 1929, Serial No. 390,698

Renewed July 26, 1934 along its upper and lower edges. A circular row of grinding balls I4 is located above the ring l2 and contacts therewith.

A yoke l5, having arms that extend between pairs of lugs IS on the inner surface of the rotatable ring I2, is driven by the vertical shaft H, which is in turn driven through reduction gearing by the motor l8. The described arrangement of the yoke arms and lugs I6 provides a floating drive connection for the grinding ring l2.

A non-revoluble ring IS with a ball race 20 along its lower edge is located above the row of balls l4. A pressure ring 2| contacts with the upper edge of the ring I9 and is provided with an and efiective means for normally maintaining a desirable level of material in one grinding stage and reducing the rate of flow of material while therein, to thereby increase the fineness of the material delivered to a successive grinding stage. I

The invention will be understood from the description in connection with the accompanying drawings in which Fig. 1 is a vertical section 0 through an illustrative embodiment of the invention; Fig. 2 is a section along the line 2-2 of Fig. 1; Fig. 3 is a section along the line 3-3 of Fig. 1; Fig. 4 is a plan view taken along the line 44 of Fig. 1; and Fig. 5 is an enlarged view of 35 the flow restricting provisions shown in Fig. 1.

In the drawingsreference character I indicates a base or support to which the bottom 2 of the grinding mill is attached by means of bolts 3. The wall 4 of the mill extends upwardly from. the

0 base 2 and is supported thereon. The wall 4 constitutes a casingwhich surrounds the grinding elements and other parts of the machine,

A cylindrical outlet 5 for the fine particles of ground material is provided at the top of the 45 68.81118 4.

A wind box 6 is provided around the lower portion of the wall 4 and an inlet I for air under pressure from any convenient source leads to the wind box 3.

A lower stationary grinding ring 8 rests upon supporting posts 3 on thebottom 2 and is providedwith a ball race) for a. circular row of grinding balls A rotatable driving ring I2 is located above the 55 row of balls' II and is provided with ball races I3.

upwardly extending flange 22 along its inner. edge. Lugs 2| (Fig. 3) are attached to the casing 4. Theselugs project into vertical slots between lugs 2| that are attached to the ring 2| so that the ring 2| is prevented from rotating, but is permitted to move up and down.

A ring 23, similar to the ring 2|, but having a depending flange 24 near its inner edge, is located above the ring 2|. Lugs 25 on the inside of the flange 22 and lugs 26 on the inside of the v flange 24 are connected by bolts 21 so that the rings 2| and 23 may move toward and away from each other and are limited in the distance they can move apart by the bolts 21. A series oi! compression springs 23 are interposed between the rings 2| and 23.

spherically shaped sockets 29 are attached to the upper edge of the ring 23. Rods 30 with ball shaped lower ends are connected to the sockets 29. The upper ends of the rods 30 are threaded and'threaded sleeves 3| are screwed on them. The sleeves 3| are revolubly supported in bearings 32 on'the outside of the casing 4. The sleeves 3| are provided with external gears 34 that are driven by worm gears on the shafts 35 of the hand wheels 36. The rods 30 pass through stuffing boxes 31 in, the wall 4 to prevent escape of dust. x

A conically shaped classifier or separator 40 is located below the outlet 5 with its-upper edge portion of the Wall 4 into the space between the.

deflector 4| and the balls I 4.

An annular outwardly flaring wall or baflle I4 is located around the outside of the row of balls II and is of somewhat larger diameter than the dimeter of the row of balls. The lower edge of the wall or baflle 44 rests upon an annular ring plate II that is L-shaped in cross section and is adjustable up and down by means of arms 46 attached thereto that are supported by rods 41 having adjusting nuts at the upper ends thereof on opposite sides of brackets 48 which are attached to the wind box 6. A flat plate I! is attached to the lower edge of the horizontal flange of the ring plate '45. The inside diameter of the flat ring I. is approximately the same as the outside diameter of the driving ring 12, so that the space for escape of material from the outside of the row of balls I4 downwardly can be adjusted to regulate the size of particles that pass therethrough by the position of the flat plate 48.

Openings 50 are provided through the wall I from the lower portion of the wind box 6. A wall sheet metal SI is provided from the grinding ring I to the wall 4 at a point above the upper ends of the openings II. Ports 52 are provided through the annular ring 8 from the space outside of the wall Ii to permit air to pass from the box I through the inside of the ring 8.

The operation is as follows:

The ring I! is driven by the yoke l5, thus causing the rows of balls II and. to turn against the grinding surfaces. Material to be ground is introduced through the-feed pipe or conduit 43 into the-space alongthe outside of the deflector I from which it passes through the row of balls I and receives preliminary grinding. The baflle l4 retains the material until it is sufliciently ground to pass through the space between the ring plate 40 and the ring l2. Partially ground material falls through this'space and may flll the space inside of the wall from which it passes through the row of balls II which finish the grinding. The flne particles are picked up by air entering through the inlet 1 and passing from 'the box I through the ports I! along the inside of the row of balls I I. The air carrying the ground particles passes upwardly and around the upper edge of the separator II and under the lower edge of the outlet 5. The heavier particles are separated out and fall to the bottom of the separator II from which they pass through the outlet 42 into the space outside'of the deflector II and thence again through the rows of balls to be further ground.

The pressure of the springs 28 can be regulated by turning the hand wheels 36, thus varying the pressure between the grinding balls and the grinding rings. Also, the rate of grinding is automatically regulated by the rate of feed of material, since the layers of material that are being ground cause the ring II to rise and compress the springs 28, thereby creating greater pressure upon the grinding balls. At very light loads the bolts 21 preventthe ring 2| from descending below a predetermined position thereby relieving the pressure upon the balls when only thin layers of the material are present between the balls and the grinding surfaces.

The rods 30 can be drawn upwardly by means of the hand wheels 36, thus carrying the rings 23, 2| and i9 upwardly so that the balls or other worn or injured parts can be reached for replacement or repair. The balls ll of the upper row that produce the initial grinding may, if desired, be made larger than the balls in the row i l. The size of the particles that pass from the upper row of balls to the lower roll of balls is regulated by the position of the ring plate 49 relative to the upper edge of the grinding ring l2.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form of our invention known to us, those skilled in the art will understand that changes may bemade in the form of the apparatus and character of the carrier medium disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used without a corresponding use of other features. In our claims, the word air is used generically to cover any gaseous carrier medium suitable for remov ing pulverized material in the manner described.

We claim: a

1. In a grinding mill, a plurality of rows of rotating grinding elements, means for feeding material to one row of said elements in one direction and to another row in the opposite direction, and. means to limit the size of particles that pass from one row to the other.

2. In a grinding mill, a plurality of rows of rotating grinding elements, means for feeding material to one row of said elements in one direction and to another row in the opposite direction, and means to limit the size of particles that pass from one row to the other, said last named means comprising an adjustable ring.

3. ma grinding mill, a plurality of rows of rotating grinding elements, means for feeding material to one row of said elements in one direction and to another row in the opposite direction, a stationary baflle around the outside of one row of said elements, and means to cause an air current to pass upwardly through the inside of said rows of elements.

4. In a grinding mill, two circular rows of rotating grinding elements, a driving ring between said rows, 2. deflector inside of one ofsaid rows, a baflle along the outside of said row of elements, means for adjusting said baflle vertically to vary the distance between it and said driving ring and a feed inlet'extending into the space between said row and said deflector.

5. In a grinding mill, two circular rows of rotating grinding elements, a driving ring between said rows, 9. deflector inside of one of said rows,

an adjustable plate along the outside of said row of elements, means to adjust said plate to regulate the size of particles passing to the other row of elements, and a feed inlet extending into the space between said row and said deflector.

6. A grinding mill comprising a casing having an inlet for material to be ground and an outlet for ground material, a plurality of vertically spaced grinding rings in said casing, 'upper and lower circular rows of rolling grinding elements positioned between corresponding pairs of grinding. rings and cooperating therewith to form successive upper and lower grinding stages, eachreceiving material to be ground at one side of for ground material, a plurality of vertically positioned between corresponding pairs of grinding rings and cooperating to form successive upper and lower grinding stages, each receiving material to be ground at one side of the corresponding row of elements and discharging ground material at the other side, baflie means for substantially restricting the flow of material while in said upper stage, and means for passing a stream of air upwardly through said. casing to said casing outlet past and receiving ground material from thedischarge side of said lower row 'of elements.

8. An air-swept grinding mill comprising a casing having an inlet for material to be ground and an outlet for ground material in the upper part of said casing, a plurality of vertically spaced grinding rings in said casing, upper and lower circular rows of rolling grinding elements positioned between corresponding pairs of grinding rings and cooperating therewith to form successive upper and lower grinding stages, each receiving material to be ground at one side of the corresponding row of elements and discharging groundi material at the other side, baiiie means at ,the discharge side of said upper row of elements for substantially restricting the flow of material while in said upper stage, and means for passing an annular stream of air upwardly through said casing to said casing outlet and mainly adjacent to and past the discharge side of one of said rows of elements.

9. An air-swept grinding mill comprising a substantially air-tight casing having an outlet for ground material in the upper part thereof and enclosing parts forming successive vertically spaced upper and lower grinding stages, means for delivering material to be ground to said upper grinding stage, means at the discharge side of said upper stage arranged to substantially restrict the fiow of material while in said upper stage, and means for directing a stream of air upwardly through said casing adjacent to .and

mainly past the discharge side of said lower grinding stage and conveying the material discharged therefrom towards said casing outlet.

10. An air-swept grinding mill comprising a substantially air-tight casing having an outlet for ground material in the upper part thereof and enclosing vertically spaced upper, intermediate and lower grinding rings, circular rows of rolling grinding elements positioned between said upper-and intermediate and said intermediate and lower grinding rings and cooperating therewith to form an upper grinding stage having an outward flow of material therethrough and a lower grinding stage receiving material from said upper stage and having an inward flow of material therethrough, a drive shaft arranged axially of said grinding rings, means forming a rotary jdrive connection between said shaft and intermediate grinding ring, means preventing ro-.- tation of said upper and lower grinding rings, means for delivering material to be ground to the inner side of said upper row of elements, and means at the outer side of said upper row of elements for substantially restricting the outward flow of material whilein said upper stage, an air box surrounding said casing, and means for directing an annular stream of air from said air box' upwardly through said casing adjacent to and mainly past the inner side of said lower row of elements and conveying the material discharged therefrom towards said casing outlet.

11. A grinding mill comprising a casing having an inlet'for material to be ground and an outlet ing rings and cooperating therewith to form sue-q cessive upper and lower grinding stages, eachrespaced grinding rings in said casing, upper and lower circular rowsof rolllnggrinding-elements positioned between corresponding pairs, o f grindceiving material to be ground'at onesideoi the corresponding row of elements and discharging ground material at the other side, and baflie means at the discharge side of and out of contact with said upper row of elements and arranged to cooperate with the lower grinding ring of said upper stage to normally maintain a level of mag terial in said upper stage and substantially restrict the rate of bow of material while in said upper stage.

12. A grinding mill comprising a casing having an inlet for material to be ground and an outlet corresponding row of elements and discharging ground material at the other side, and an upwardly flaring frusto-conical baflle arranged at the discharge side of and out of contact with said upper row of elements and extending above the center line thereof and positioned to cooperate with the lower grinding ring of said upper stage in substantially restricting the rate of flow of material while in said upper stage..

13. A grinding mill comprising a casing having an inlet for material to be ground and an outlet for ground material, a plurality of vertically spaced grinding rings in said casing, upper and lower circular rows of rolling grinding elements positioned between corresponding pairs of grinding rings and cooperating therewith to form successive upper and lower grinding stages, each receiving material to be ground at one side'of the corresponding row of elements and discharging ground material at the other side, and means at I the discharge side of said upper row of elements for substantially restricting the rate of flow of material while in said upper stage comprising a normally stationary annular plate extending from the inner wall of said casing toward but slightly elements positioned between said upper and intermediate and said intermediate and lower grinding rings'and cooperating therewith to form upper and lower grinding stages, means for delivering material to be ground to the inner side of said upper row of elements, the parts forming saidlower stage being constructedand arranged to receive material from the outer side of said upper stage and to cause an inward flow of material through said lower stage, and baflle means at the outer side of and out of contact with said upper row of elements and arranged to cooperate with the lower grinding ring of said upper stage to normally restrict substantially the rate of outward flow of material while in said upper stage.

15. A grinding mill comprising a casing having an outlet for ground material and enclosing vertically' spaced upper, intermediate and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings and cooperating therewith to form upper and lower grinding stages, a drive shaft arranged axially of said grinding rings, means forming a rotary drive connection between said shaft and intermediate grinding, ring, means preventing rotation of said upper and lower grinding rings, means for delivering material to be ground to the inner side oi! said upper row of elements, the parts forming said lower stage being constructed and arranged to receive materialfrom the outer side or said upper stage and to cause an inward flow of material through said lower stage, and baflle means at the outer side or and out of contact with said upper row of elements and'arranged to cooperate with the lower grinding ring of said upper stage to normally restrict substantially the rate of outward flow of material while in said upper stage.

ERVIN G. BAILEY. PERRY R. CABSIDY. RALPH M. HARDGROVE.