US1875817A - Apparatus for pulverizing materials - Google Patents

Description

Sept. 6, 1932. w. J. A. LONDON 1,875,817

APPARATUS FOR PULVERIZING MATERIALS Filed Feb. 12, 1929 2 Sheets-Sheet l IL 9 9'0 ,r l6 i IN VEN TOR.

/A; A TTORNEYS.

Sept. 6, 1932. w. J. A. LONDON APPARATUS FOR PULVERIZING MATERIALS Filed Feb. 12, 1929 2 Sheets-Sheet 2 fzvrok.

/M ATTORNEYS.

Patented Sept. 6, 1932 A UNITED STATES PATENT OFFICE WILLIAM J. A. LONDON, OI HARTFORD, CONNECTICUT, ASSIGNOR TO PEAIBODY ENGINEERING CORPORATION, OF

NEW YORK, N. Y, A CORPORATION 01' NEW' YORK APPARATUS FOR PIlLmIZING MATERIALS Application at February 1::, 1929. Serial a... 339,333.

My invention relates to apparatus for reducing materials to a wdered condition and more particularly or producing powdered coal for power plants. will be understood from the following description taken in connection with the accompanying drawin in which Fig. 1 is a View in elevation, with certain parts .in section, and Fi s. 2 and 3 transverse sections on the planes 0% the lines 22 and 3-3, respective of Fig. 1. I

Referring to the drawings, the ap aratus illustratedis enclosed within a suitab e hous ing which, for convenience of description, may be considered as divided into three sections forming chambers designated generally by the letters A, B, and C. The mill, of whatever type, for efiecting the pulver1zation of the material is housed within the chamber A. From said chamber the material is caused to flow throu h the chambers B and C in a current of air induced by a fan connected to the outlet of chamber 0. In these chambers a separation is efiected between the fines and unground material in the manner hereinafter described. Any suit able design of housing may be employed to accommodate and support the several parts of the pulverizer.

The mill shown,

curedtotheshaft 4 is a disc 6 having secured thereto a plurality of hammers 7.- The ma terial to be pulverized is delivered from "a hopper 8 to a feeder 9 and thence through a chute 10 to the mill.

Above the mill is the chamber B, the inner wall 11 of which is a frustum of a cone with its smaller open end directly over and in communication with the outlet 12 of the mill.

Above the chamber B is the chamber 0, the wall of which is also a frustrum of a cone,

The inventiondesignated by the nu-. meral 1, is that of the impact type, that is the base of which coincides with the larger end of chamber B. To the outlet end of chamber C is secured' apipe 14 connected to an exhaust fan is induced to flow through the pulverizer the air entering throu h a valved pipe 1 connected to chamber 5 below disc 6.

The chamber B ma be defined as a classification chamber an ,C as a continuation thereof, into which the usable fines are drawn after their separation from the coarser or unground particles. B shall be located directly above the mill and in direct communication therewith so as to provide a free and unobstructed inlet into said chamber.

The principle of operation of the pulverizer as above described is as follows:

Assuming that coal is the material to be treated and that it is 'to-be reduced to a fineness of 200 mesh I start with it in the condition in which it is delivered from the mine,

15 by which a current of air I prefer that chamber previous drying, although this is not essential. The coal is fed to the mill in a practicall continuous stream and will be sub; jecte to the action of the-mill as soon as a given mass is brought into contact withsthe rotating hammers 7. The reduction will not be uniform but will vary by way of example rom 50 to 200 mesh. The suspended material in the mill will be set in rapid motion by the hammers and will be swept through outlet 12 by the current of air induced by fan 15 into chamber B. By reason of the expanding form of chamber B there will be a reduction in velocity of the moving mass which will permit all particles whichare of a size below the ultimate mesh to fall back into the mill to be further subjected to theaction of the hammers.

4 The suction effect of fan 12 will be so adjusted and the height and cross-sectionalareas 3 of chambers B and C. so proportioned that only the lighter particles, that is, those of the ultlmate fineness will. reach the upper part of chamber C and will be carried away bythe fan.

their size, that is, the heavier particles, say. those of 50 to 100 mesh, will be returned to the mill after a comparatively short travel in chamber B. The finer particles will be lifted further until there remains in the upper part of chamber C onlythose particles ofthe desired or ultimate fineness.

While I have shown an impact mill this does not exclude the possibility of some of the material being reduced by attrition, this being due to the condition existing in the mill itself and of the action of the particles upon one another as they are swept around the mill by the rotating hammers.

The above being the general mode of opera-' tion contemplated by me, the efiiciency of the pulverizer may be increased by the employ-v ment of some or all of thefollowing devices illustrated in the drawings.

In Fig. 1 I have shown a plate 16-attached to shaft 4 near the upper end thereof andv in approximately the plane of the outlet,of

.chamber B. As the stream of pulverized material flows upward the plate 16 offers an obstruction which will, to a more or less extent,

retard the stream and tend to throw the heavier particles against the conical wall 11 and i thus assist in the classification of the particles.

To reduce unnecessary windage in the pul: verizer and to insure better circulation, I may introduce an annular plate .17 secured by suitable means to the wall of chamber A so as to afford a passage between the plate and the upper wall of the chamber. As indicated by the the material being treated will be arrows, thrown outward by the hammers 7 toward the outer wall of chamber A and will flow in 'a substantially even and uniform stream through the passage above the plate 17. Some of the heavier particles will drop back into the path of the hammers while the other and lighter particles will be carried by the air current through outlet 12 into the classification chamber 13 where a, separation of the fines from the heavier or coarser particles will be effected in the manner before described.

Between the plate 17 and the upper wall of the mill chamber A I may introduce vanes 18' for the purpose of' lengthening or shortening the path of the stream, according to the posi# tion of the vanes, from the hammers to the outlet 12. These directing vanes may be placed as desired and as indicated by the full and broken lines in Fig. 3.

To further facilitate the clearing of the mill I may provide it with one or more elevating planes 19. These tend to lift the material more readily from the hammers to the outlet 12. The inclination of these planes as shown inFig. 1 is about 45. This inclination may be varied according to the material being treated.

The plates 16 and 17 ,the vanes 18 and the A elevating planes .19 I have introduced into the pulverizer to increase its efliciency and to fafor delivering cilitate the carrying out of the .main purinventionwhich is to effect the pose of the separation ofthe finesinthe classification chamber B somewhat in the manner indicated by the arrows. 20 in said chamber, immediately after the impact and attrition forces in the mill have acted upon, the material being treated, and the return of the coarser particles tothe mill for further treatment.

The velocity of the induced air current which carries the-material from the mill will "be so controlled as to create a condition in the classification chamber as will permit the de- --sired separation between the fines and the coarser particles to be substantially completed before or immediately after the material enters the outlet chamber C. This, of course,

is not absolute but the purpose is that the maward the outlet for directingthe material away from said hammers, to the outlet 2. A pulverizer, comprising a stat onary casing having an outlet in the upper part means for delivering the thereof, hammers supported within the cas rotating said hammers, means the material to be pulverized into the casing, deflecting blades fixed within ing, means for .the casing on a circle of greater diameter than the path of the rotating hammers, and means for causing'a current of .air to flow through said casing.

'3. A pulverizer comprising a casing, a plate near-the upper wall of the casing for separating the chamber within the'casing into upper and lower portions, 3; wheel carrying hammers supported in said lower portion, deflecting blades between the hammers and the wall. of the casing for directing the material away from said hammers into the space between said plate, and the casing, said casing having an outlet in the upper wall thereof, and means for withdrawing the pulverized material through said outlet.

4. A- pulverizer .comprising a casing having an outlet in the upperpart thereof, an

annular plate. supported within the casing and spaced from the upper wall thereof, a

wheel supported in the ing and having hammers thereon, means for rotatin said wheel, and deflectin blades between t ehammers and the wall 0 the casing lower part of the easand inclined upwardlv and outwardly from points adjacent the outer ends of the hammers for directing the material away from said'hammers into the space between said plate and upper wall of the casing.

5. A pulverizer comprising a casing having an outlet in the upper part thereof, a wheel supported in proximity to the lower ride of the casing, hammers on said wheel terminating in spaced relation to the side of the casing means for rotating said wheel, means for introducing the material to be pulverized into the casing in the path of the hammers, deflecting blades between the outer ends of the hammers and side of the casing for directing the pulverized material from the hammers to the curved side of the casing, and means for withdrawing the pulverized material through said outlet.

6. A pulverizer comprising a casing having an outlet in the upper part thereof, a wheel carrying hammers supported in proximity to. the lower side of the casing, means for rotating said wheel, an annular plate supported within the casing above said hammers and spaced from the upper wall of the casing to provide a passage around the side and top of the casing for the pulverized material, vanes in said passage, and means for causing a current of air to flow through said casing and passage for conveying away the ground material, to the outlet. v

7. A pulverizer comprising a casing having an opening in itstop, a separating chamber extending above the casing communicating with the opening and provided with an outlet, a shaft mounted through said casing and extending into the separating chamber, hammers supported on said shaft in the lower portion of the casing, means for rotating said shaft and hammers, means for delivering materials to be ground into the casing in the path of the hammers, the wall of the casing beyond the hammers being curved, and deflector blades in the casing between the hammers and the curved wall and inclined to direct the materials from the hammers toward the separating chamber.

8. The structure of claim 7 wherein the separating chamber has a conical wall leading to the outlet and a baflle is mounted on the shaft between the outlet and the opening in the casing.

Signed at New York, in the county of New York and State of New York, this 16th day of January A. D. 1929.

WILLIAM J. A. LONDON.

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