US2977055A

US2977055A - Apparatus for pulverizing coal and the like

Info

Publication number: US2977055A
Application number: US746118A
Authority: US
Inventors: Frank A Fawcett
Original assignee: Bath Iron Works Corp
Current assignee: Bath Iron Works Corp
Priority date: 1958-07-02
Filing date: 1958-07-02
Publication date: 1961-03-28
Anticipated expiration: 1978-03-28

Description

March 28, '1 961 F. A. FAWCETT APPARATUS FOR PULVERIZING COAL AND THE LIKE 2 Sheets-Sheet 1 Filed July 2, 1958 INVENTOR. 1 7517 FA [fin 0e27, BY

ATTORNEYS March 28, 1961 F. A. FAWCETT 2,977,055

APPARATUS FOR PULVERIZING COAL AND THE LIKE Filed July 2, 1958 2 Sheets-Sheet 2 I INVENTOR.

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Unite Sates Patent APPARATUS FOR COAL AND THE LIKE Frank A. Fawcett, Gladwyne, Pa., assignor to Bath Iron Works Corporation, Bath, Maine, a corporation of Maine Filed July 2, 1958, Ser. No. 746,118

2 Claims. (Cl. 241-86) This invention relates to improvements in apparatus for pulverizing coal and the like, and more particularly concerns a coal pulverizer known as the Coalpactor because it reduces coal by the impact reduction principle.

Conventional hammermill' type crushers are generally limited in the degree of pulverization obtainable from them to a maximum of eighty-five percent minus one eighth inch, since impractical amounts of minus 100 mesh coal are produced at higher pulverization levels. For example, to produce a coal having a pulverization of ninety percent minus one-eighth inch, conventional equipment produces seventeen to twenty-three percent minus 100 mesh coal, which is objectionable.

It is an object of this invention to provide a coal pulverizer which is capable of producing various degrees of pulverization without producing impractical amounts of minus 100 mesh coal commonly termed bug dust.

It is another object of this invention to provide a pulverizer which is capable of producing a degree of pulverization which exceeds eighty percent minus one-eighth inch (that is, the coal is reduced to such a size that over eightyv percent of it is small enough to pass through a screen having one-eighth inch square openings). It is another object to provide a pulverizer also capable of producing degrees of pulverization less than eighty percent minus one-eighth inch.

It is another object of this invention to provide a pulverizer having breaker blocks which do not build up and plugwith wet coal, and thus do not decrease the reduction qualities of the pulverizer.

It is another object of this invention to provide a pulverizer which includes control means for varying the degree ofpulverization as desired.

Other objects and advantages of this invention, including the simplicity and economy of the same, as well as the. ease with which it may be adapted for use withexisting equipment, will further become apparent hereinafter and in the drawings, inwhich:

Fig. 1 is a view in central longitudinal section and partly in elevation of'a pulverizer constructed in accordance with this invention;

Fig. 2 is a view in cross section of the pulverizer shown in Fig. 1, taken as indicated by the lines and arrows IIII which appear in Fig. 1;

Fig. 3 is an enlarged view in perspective of a breaker block element which is a part of this invention; and

Fig. 4 is an enlarged view in perspective of another breaker block element which forms a part of this invention.

Although specific terms are used for clarity in the following description, these terms are intended to refer only to the structure shown in the drawings and are not intended to define or limit the scope of the invention. Further, the term coal as used in the specification also includes like materials.

Turning now to the specific embodiment of the invention selected for illustration in the drawings, there is shown a coal pulverizer known as a Coalpactor" which Patented Mar. 28, 1961 2 includes a frame 11 having formed therein a feed hopper 12, a reversible hammer rotor 13 rotatably mounted within the frame and positioned below feed hopper 12, a delivery chute 14 positioned below hammer rotor 13, and breaker block mechanism 15 mounted on the inside of frame 11 and positioned about hammer rotor 13.

Hammer rotor 13 includes a rotor 16 and hammers 17 which when rotated define a hammer circle 18.

Breaker block mechanism 15 includes an upper breaker block 21, an intermediate breaker block assembly 22, and a lower breaker block assembly 23.

Intermediate breaker block assembly 22 is provided with a breaker block support 24 having a rib 25. Mounted on breaker block support 24 is an intermediate breaker block which is formed of two elements, an upper intermediate breaker block 27 and a lower intermediate breaker block 28. Breaker block 27 is provided with a' slotted lug 31 which is received by an aperture in breaker block support 24 and affixed to support 24 through the action of wedge-shaped key 32. Lower intermediate breaker block 28 is provided with a slotted lug 33 which is received by an aperture in breaker block support 24 V and afiixed to the support by wedge-shaped key 34. 1

ing throat 52' located between hammer circle 18 and lower breaker block 41, and an intermediate throat 53' Intermediate breaker block assembly 22 is pivotally connected at its lower end to the interior of frame 11 by rod '35. Breaker block assembly 22 is adjustable as to distance from hammer circle 18 through the action of an externally mounted jack bolt 36 which is connected to breaker block assembly 22 at jack head 37.

Positioned below intermediate breaker block assembly 22 is the lower breaker block assembly 23 which includes a perforated grinding block or lower breaker block 41 which is provided with a slotted lug 42 which is received by a recess in the lower breaker block support 43. A wedge-shaped key 44 holds the lower breaker block 41 in place. Lower breaker block assembly 23 ispivotally connected to the interior of frame 11 by rod 45 and lower breaker block 41 is adjustable as to distance from hammer circle18 through the action of an externally mounted jack bolt 46 which is connected to block assembly 23 at jack head 47.

It is to' be noted that, the construction of intermediate hreaker block assembly 22 is such that there is a narrowing throat 51 located between hammer circle 18. and intermediate breaker block 28. There is a lower narrowlocated between-the lower end of breaker ,block28 and theupper end of breaker block 41 and hammer circle 18. Intermediate throat 53 is wider than the narrowest portion of narrowing throat 51.

For the Coalpactor having a thirty-eight inch diameter hammer circle, the dimensions are as follows. Intermediate breaker block 28 is a smooth, arcuate breaker block and is positioned on a radius 54 which is displaced from the center of rotation of hammer rotor 13. As shown in Fig. 2, radius 54 is twenty-three and one quarter inches long and is drawn from a center point 55 which is displaced three inches from the center of rotation of hammer rotor 13. The reversed curve of the upper portion of upper intermediate breaker block 27 is drawn from a center point 56 and has a radius ofone and threequarter inches. Center point 56 is displaced thirteen and three-eighths inches horizontally from the center of rotation of hammer rotor 13 and is displaced vertically nineteen inches from the center of rotation of hammer rotor 13.

For the Coalpactor having a forty-four inch diameter hammer circle, the dimensions are as follows as shown in Fig. 2 in parenthesis. Intermediate breaker block 28 is a smooth, arcuate breaker block and is positioned on a radius 54 which is displaced from the center of rotation of hammer rotor 13. Radius 54 is twenty-nine and a half inches long and is drawn from a center point 55 which is displaced six inches from the center of rotation of hammer rotor 13. The reversed curve of the upper portion of upper intermediate breaker 27 is drawn from a center point 56 and has a radius of six and seven-eighths inches. Center point 56 is displaced twenty and threeeighths inches horizontally from the center of rotation of hammer rotor 13 and is displaced vertically twenty-five inches from the center of rotation of hammer rotor 13.

In operation, the coal to be pulverized is fed to the pulverizer through feed hopper 12. As the coal falls toward hammer rotor 13, it is struck by the hammers 17 and thrown against the breaker block mechanism 15. Coal then rebounds back to the hammers and the process is repeated until the pulverized coal is delivered from the pulverizer through the delivery chute 14.

The pulverizer constructed in accordance with this invention provides an unusual and surprising result in the pulverizing of coal, in that a high degree of pulverization is obtained without creating an objectionable amount of bug dust (minus 100 mesh coal). In addition, breaker block mechanism 15 does not build up and plug with wet coal, as does conventional apparatus. This is of advantage since when breaker blocks become plugged with wet coal and the like, the degree of pulverization obtainable decreases.

Provision is made for varying the degree of pulverization obtained from the pulverizer by providing

breaker block assemblies

22, 23 which are adjustable as to distance from the hammer circle 18.

In the pulverizing of low volatile coal, it has been found that with the hammermill rotor operating at a speed of 690 rpm, with lower breaker block 41 adjusted for one half inch clearance between it and hammer circle 18, and with coal being fed to the pulverizer at a rate of thirty to thirty-five tons per hour, the degree of pulverization obtained was in excess of ninety percent minus one-eighth inch. The percentage of minus 100 mesh coal delivered by the pulverizer was only 10.67 percent. This 10.67 percent figure does not indicate the amount of minus 100 mesh coal created by the pulverizer, since it also includes the amount of minus 100 mesh coal which was delivered to the pulverizer in the coal feed. minus 100 mesh coal contained in the pulverizer feed was made.

In other tests, with a feed rate of 33.7 tons per hour, and with a hammermill speed of rotation of 690 r.p.m., the average degree of pulverization obtained was 87.2 percent minus one-eighth inch and 11.2 percent minus 100 mesh, with the pulverizer feed containing 2.7 percent minus 100 mesh.

No analysis of the It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred embodiment. Various changes may be made in the shape, size, and arrangement of parts. For example, equivalent elements may be substituted for those illustrated and described herein, parts may be reversed, and certain features of the invention may be utilized independently of the use of other features, all without departing from the spirit or scope of the invention as defined in the subjoined claims.

Having thus described my invention, I claim:

1. In a pulverizer for coal and the like, having a frame, the combination of a hammer rotor rotatably supported in the frame and defining a hammer circle when rotated; a smooth-surfaced curved upper breaker block concavely rounded on an arc of which the center is displaced laterally from the axis rotation of the hammer rotor, said block being pivotally supported at its lower end Within the frame and positioned to form a gradually downwardly narrowing upper throat with the hammer circle around an upper quadrant of said circle substantially down to the horizontal plane through the axis of the hammer rotor; a lower breaker block pivotally supported at its upper end in the frame adjacent the pivot of the upper block, said lower block having a flat smooth-surfaced upper portion forming with the hammer circle, a lower throat shorter and more abruptly narrowed downwardly than the upper throat, and a lower flat-surfaced receding portion in wide obtuse angular relation to said smooth upper portion provided with small perforations; and separate means for independently adjusting the upper and lower blocks about their respective pivots toward or away irom the hammer circle to vary the taper of the upper and lower throats.

2. A pulverizer according to claim 1, wherein the pivots for the upper and lower breaker blocks are located respectively above and below the horizontal plane through the axis of the rotor; and wherein the lower breaker plate has an outwardly extending rounded marginal portion at the top which underreaches the bottom edge of the upper breaker plate.

References Qited in the tile of this patent UNITED STATES PATENTS 1,864,973 Buchanan June 28, 1932 1,872,233 Borton Aug. 16, 1932 2,478,733 Wright Aug. 9, 1949 2,482,279 Lemmon et al. Sept. 20, 1949 2,767,929 West Oct. 23, 1956 FOREIGN PATENTS I 730,261 France May 9, 1932