US2220105A - Pulverizer - Google Patents

Description

A NOV. 5, 1940. w, g L z 2,220,105

PULVERIZER Filed April 28 1957 Y 4 Sheets-Sheet 2 I V INVENIOR.

Lewis WHel/QP I V I ATTORNEY.

Nov. 5, 1940. L; W. HELLER PULVERIZER Filed April 28 1937 4 SheeiS-Shet .3

2 ,WQM

Lewis WHel/en 1 L. W. HELLER Nov. 5, 1940.

' PULVERIZER Filed April 28. 1937 4 Sheets-Sheet 4 INVENTOR. Zen 2's WHel/er- ATTORNEY.

. Patented Nov. 5, 1940 PATENT OFFICE PULVERIZER Lewis W. Heller, East'Orange, N. J., assignor to The Babcock drwilcox Company, Newark, N. J., a corporation of New Jersey Application April 28, 1937, Serial No. 139,374

10 Claims. (CI. 8345) noise, and a highly fficient pulverization and separation of the material being treated. A fur- 15 ther and more specific object is the provision of a pulverizer of the type described with an upper rotary grinding ring fixed on the main drive shaftin conjunction with means for resiliently supporting one or more associated non-rotary,

go lower grinding rings and circular rows of grinding elements and exerting an adjustable grinding pressure thereon.

The various features of novelty which .characterize my invention are pointed out with par- 35 ticularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying 3o drawings and descriptive matter in which I have illustrated and described several embodiments of my invention.

Of the drawings: Fig. 1 is a sectional elevation of a single stage 35 pulverizer constructed in accordance with my invention;

Fig. 2 is a horizontal section taken on the line 22 of Fig. 1;

Fig. 3 is a sectional elevation of a modified con- 4o struction of a single stage pulverizemand Fig. 4 is a sectional 'elevationof a two-stage pulverizer.

The pulverizer illustrated in Figs. 1- and 2 has the grinding parts enclosed within a cylindrical 5 casing l having a spout H for supplyingi'naterial to be pulverized opening through one side thereof and outlet pipes l2 for material-laden air symmetrically arranged in the top wall I3 of the casing. The grinding parts for the pulverizer 50 comprise a non-rotary metallic lower or bottom grinding ring l having a track formed on its upper face for a circular row of rolling grinding elements, preferably in the form of metallic balls I 6. The balls I6 are positioned between the lower 55 ring and a top or upper rotary, grinding ring H,

which is rigidly mounted on a main drive shaft l8. The drive shaft 18 extends axially of the grinding rings and ball row and is positioned against vertical and lateral movements by suittable bearings at vertically spaced points. In 5 the pulverizer illustrated the drive shaft [8 extends through the casing top wall l3 and its projecting end is operatively connected by the drive mechanism indicated to a suitable electric motor (not shown). 10 With the described construction of the grind ing parts, material will be delivered to the outer side of the ball row and forced inwardly therethrough by gravity and by the action of plows l 9 mounted on the periphery of the upper ring ll. The grinding balls are held in grinding contact with the grinding'rings and a grinding pressure exerted on the grinding parts by a resilient sup-' port of the lower grinding ring 15. The ring I5 is held in a non-rotary floating position relative to the casing III by means of projecting lugs 20 engaging plates 2| on the side wall of the casing, and by a series of coiled pressure springs surrounding the upper ends of supporting rods 26 which extend through the casing top wall. The 25 rods 26 have a fixed detachable connection with l the bottom grinding ring I5 by nuts 22 on the lower threaded end of the rods. The projecting upper ends of the rods are also threaded and carry an adjustable thrust plate 21 between which and the top wall of the casing the pressure springs 25 extend so that a resilient thrust is exerted upwardly by the rods 26 on the lower grinding ring l5 and through the balls l6 against the upper grinding ring, so that a grinding pressure will be exerted on any material passing between the balls and rings.

The upper grinding ring has a series of curved passages 29 extending therethrough providing a flow path from the inner side of the ball row to the portion of the casing above the grinding parts. An annular flow passage 30 is defined from the lower part of the casing past the inner side of the ball row to the passages 29 by means of a conical extension 3| of the upper ring extending below the lower grinding ring IS. A conduit 32 opens through the side wall of the casing below the grinding parts through which a stream of a suitable gaseous carrier medium, preferably preheated air, is delivered to the lower portion of 60 the casing. The lower grinding ring carries an upwardly flaring annular plate 33 of flexible metal on its periphery which extends to and in sliding contact with the casing side wall to seal the space between the outer side of the ring l5 and the side wall of the casing against the passage oi air; The supporting rods 26 extend through sealed passages in the plate 33.

With this arrangement a stream of air will be directed upwardly past the entire inner discharge side of the ball row, and outwardly through the upper rotating grinding ring passages 29 to the casing outlets l2. The material to be pulverized drops from the spout H to the outer side of the ball row, and is pulverized as it passes inwardly between the grinding rings and balls. The pulverized material discharging at the inner side of the ball row is swept up by the air stream and carried therewith upwardly and outwardly through the upper grinding ring passages to the mill outlets. The ring partitions defining the passages 29 exert a swirling action on the material-laden air exiting from the passages, conin weight.

tributing to the subsequent classification and separation of the coarse particles. The coarse particles of material tend to separate in the upper portion of the casing and to drop back to the outer side of the ball row for further pulverization. The central portion of the upper grinding ring is covered by a conical plate 34 which facilitates the return of separating coarse particles to the outer side of the ball row.

The described construction of the upper rotary grinding ring providing for its rotation in a horizontal plane normal to the axis of the driving shaft [8, and the arrangement of the pressure springs so as to exert a resilient grinding pressure upwardly on the lower grinding ring and balls are, particularly advantageous in minimizing stresses and wear on the driving parts. By minimizing any unbalanced rotational forces the rotating grinding parts can be substantially reduced The adjustable parts are confined to non-rotary elements whereby regulation during operation is possible. The resilient support of the lower grinding ring also expedites the passage of material through the grinding zone because of the vibratory movement of the lower ring.

In the modified construction shown in Fig. 3, coiled pressure springs 35 are positioned directly below the lower grinding ring l5 and the spring pressure controlled by adjustment of the position of the thrustplates 40 through corresponding screws 41 extending through the bottom of the pulverizer casing. The drive shaft l8 has a drive connection at its lower end. A rotary bladed classifier 42 is mounted on the upper end of the shaft l8 for exerting an additional classifying effect on the material carried in the air stream before passing out through the casing outlets l2. The described arrangement of the pressure springs causes the impact forces to be transmitted directly to the foundation rather than through the casing as in Fig. 1. The pulverizer construction and operation is otherwise similar to the construction shown in Figs. 1 and 2.

The modified construction illustrated in Fig. 4 differs from that shown in Fig. 3 by the provision of a pair of concentric lower non-rotary floating grinding rings 50 and 5| each of which is independently resiliently supported by a circular series of coiled pressure springs 52 in the same manner as the lower grinding ring of Fig. 3. The grinding track on the outer lower ring is at a higher level than that on the inner lower ring to expedite the passage of material through the two grinding stages. The outer ring 50 is floatably positioned within the casing in the described manner and similar provisions between the inner and outer grinding rings prevent relative rotation of the inner grinding ring but permit vertical movement-thereof. In this construction the up- 1 pergrlnding ring 53 is provided with a pair of concentric grinding tracks at different levels which contact with inner and outer rows of grinding balls 54 and 55 respectively, supported on the corresponding lower grinding rings. The upward thrust of the springs 52 maintains the balls 54 and 55 against the upper grinding ring 53 and by selection of the spacing and adjustment of the springs the grinding pressure in the two concentric stages can be adjusted as desired.

The material to be pulverized is delivered to the outer side of the outer row of balls 55 and passes inwardly through the ball rows under the action of gravity and the plows l9. Carrier air enters the pulverizer casing through the conduit 32 below the lower grinding rings. The lower grinding rings are slightly spaced apart to form an annular passage 56 therebetween through which part of the air stream passes upwardly past the inner side of the outer row of balls. Passages 51 are provided in the upper grinding ring similar to the passages 29 in Figs. 1 and 3, except that the passages 51 have an opening 58 between the upper grinding ring tracks to permit the materialladen air from the inner side of the outer row of balls to pass therethrough. The velocity and quantity of the air through the passages 56 and 51 are merely sufficient to pick up the more finely pulverized material, permitting the remainder to pass inwardly to the ball row 54.v The partly pulverized material is subjected to further grinding by the inner row of balls. On being discharged through the inner row of balls this material is swept up by the second annular stream of air passing upwardly at the inner side of the grinding ring 5| through the passage 30. The material-laden air enters the passage 51 and joins the other stream of material-laden air carrying material swept up from the outer row of balls. The centrifugal effect imparted by passages 51 will create a swirling in the upper part of the casing and effect separation before reaching the separator 42. The pulverizer. construction and operation is otherwise similar to the pulverizer shown in Fig. 3.

While in accordance with the provisions of the statutes I have illustrated and described herein the preferred forms of my invention known to me, those skilled in the art will understand that changes may be made in the form of the apparatus and character. of the carrier medium disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features. In' the claims, the term air is used generically to cover any gaseous carrier medium suitable for removing pulverized material in the manner described.

I claim:

l. A pulverizer comprising a casing enclosing a drive shaft, an upper rotary grinding ring rigidly mounted on said drive shaft, a lower nonrotary floating grinding ring, a circular row of rolling grinding elements positioned between said grinding rings, means for delivering material to be pulverized to one side of said row of grinding elements, means resiliently supporting and exerting a grinding pressure on said lower grinding ring and elements, means for directing a stream of carrier air upwardly past the discharge side of said row of grinding elements to sweep up pulverized material, and an annular baiile at the material inlet side of said lower grinding ring arranged to prevent the passage of air upwardly past the material inlet side of said lower grinding ring.

2. A pulverizer comprising a casing enclosing a drive shaft, an upper rotary grinding ring rigidly mounted on said drive shaft, a lower nonrotary floating grinding ring, a circular row of rolling grinding elements positioned between said grinding rings, means for delivering material to be pulverized to one side of said row of grinding elements, a group of coiled pressure springs in said casing below and resiliently supporting said lower grinding ring from the bottom of said casing and exerting a grinding pressure on said lower grinding-ring and elements, externally operable means for adjusting the pressure of said springs, and means for directing a stream of carrier air upwardly past the discharge side of said row of grinding elements to sweep up pulverized material.

3. A pulverizer comprising a casing enclosing a drive shaft, an 'upper rotary grinding ring rigidly mounted on said drive shaft, a lower nonrotary floating grinding ring, a circular row of rolling grinding elements positioned between said grinding rings, means for delivering material to be pulverized to the outer side of said row of grinding elements, means resiliently supporting and exerting a grinding pressure on said lower grinding ring and elements, means for directing an annular stream of carrier air below said lower grinding ring and upwardly past the inner side of said row of grinding elements to sweep up pulverized material, and an annular baffle at the outer side of said lower grinding ring arranged to prevent the passage of air upwardly past the outer side of said lower grinding ring.

4. A pulverizer comprising a casing enclosing a drive shaft, an upper rotary grinding ring rigidly mounted on said drive shaft, a lower non-rotary floating grinding ring, a circular row of rolling grinding elements positioned between said grinding rings, means for delivering material to be pulverized to the outer side of said row of grinding elements, a group of coiled pressure springs below and resiliently supporting said lower grind-' ing ring from the bottom of said casing and exerting a grinding pressure on said lower grinding ring and elements, a plow mounted on said upper grinding ring at the outer side of said row of grinding elements, means for directing an annular stream of carrier air upwardly through said casing past the inner side of said row of grinding elements to sweep up pulverized material, and an annular baffle at the outer side of said lower grinding ring arranged to prevent the passage of air upwardly past said outer side of said lower grinding ring.

5. A pulverizer comprising a casing enclosing a drive shaft, an upper rotary grinding ring rigidly mounted on said drive shaft and havingpassages extending therethrough, a lower non-rotary floating grinding ring, a circular row of rolling grinding elements positioned between said grinding rings, a circular group of coiled pressure springs positioned below said lower grinding ring and arranged to resiliently support and exert a grinding pressure on said lower grinding ring and elements, means for delivering material to be pulverized to the outer side of said row of grinding elements, means for directing an annular stream of carrier air upwardly past the inner side of said row of grinding elements and thence convey pulverized material from the inner side of said row of grinding elements to the upper part of said casing, and an annular bafiie at the outer side of said lower grinding ring arranged to prevent the passage of air upwardly past the outer side of said lower grinding ring.

6. A pulverizer csmprising a casing enclosing an upper rotary grinding ring having passages extending therethrough, a lower non-rotary floating grinding ring, a circular row of rolling grinding elements positioned between said grinding rings, a vertical drive shaft extending axially of said grinding rings and row of grinding elements, means for rigidly mounting said upper grinding ring on said drive shaft, means for resilientlysupporting and exerting a grinding pressure on said lower grinding ring and elements, means for delivering material to be pulverized to the outer side of said row of grinding elements, and means for directing an annular stream of :carrier air upwardly past the inner side of said row of grinding elements and thence through said upper grinding ring passages to convey pulverized material from the inner side of said row of grinding elements to the upper part of said casing.

'7. A pulverizer comprising a casing enclosing an upper rotary grinding ring, a plurality of concentric lower non-rotary grinding rings, a plurality of concentric rows of rolling grinding elements positioned between said upper and said lower grinding rings, means for delivering material to be pulverized to one side of said rows of grinding elements, means for resiliently supporting and exerting a grinding pressure on said lower grinding rings and elements, and means for directing a stream of carrier air upwardly past the discharge side of each of said rows of grinding elements to sweep up pulverized material.

8. A pulverizer comprising a casing enclosing a drive shaft, an upper rotary grinding ring rigidly mounted on said drive shaft, a plurality of concentric lower non-rotary floating grinding rings, a plurality of concentric rows of rolling grinding elements positioned between said upper and said lower grinding rings, means for delivering material to be pulverized to one side of said rows of grinding elements, separate concentric groups of .coiled pressure springs for resiliently supporting from thebottom of said casing and exerting a grinding pressure on said lower grinding rings and elements, and means for directing a stream of carrier air upwardly past the discharge side of said rows of grinding elements to sweep up pulverized material.

9. A pulverizer comprising a casing enclosing an upper rotary grinding ring, a plurality of concentric lower non-rotary grinding rings, a plurality of concentric rows of rolling grinding elements positioned between said upper and said lower grinding rings, means for delivering material to be pulverized to the outer side of said rows of grinding elements, means for resiliently supporting and exerting a grinding pressure on said lower grinding rings and elements, and means for passing a stream of carrier air upwardly past the inner side of each of said rows of grinding elements to sweep up pulverized material.

10. A pulverizer comprising a casing enclosing an upper rotary grinding ring having passages extending therethrough, inner and outer lower non-rotary grinding rings, a circular row of rolling grinding elements positioned between said upper grinding ring and each of said lower grinding rings, a vertical drive shaft extending axially of said grinding rings and rows of grinding elements, means for rigidly mounting said upper grinding ring on said drive shaft, a circular group of coiled pressure springs positioned below each of said lower grinding rings and arranged to resiliently support and exert a grinding pressure on the corresponding lower grinding ring and row of grinding elements, means for delivering material to be pulverized to oneside of said rows of grinding elements. and means for directing an annular stream of carrier air upwardly past the discharge side of each of said rows of grinding elements and thence through said upper grinding ring passages to convey pulverized material from the discharge side of said rows of grinding elements to the upper part of said casing.

' LEWIS W. HELLER.

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