US1822999A - Pulverizing mill - Google Patents

Description

Sept. 15, 1931. c, PETERS 1,822,999

PULVERIZING MILL Filed Sept. 24, 1930 Patented Sept. 15 1931 UNITED CLAUDIUS PETERS, 01F HAMBURG, GERMANY PULVERIZING MILL Application filed September 24, 1930, Serial No. 484,011 and in Germany May 10, 1928.

My invention relates to pulverizing mills and more particularly to mills of the type in which the lighter particles of thepulverized material are separated from the coarser par- 5 ticles by flowing gas.

It is an object of my invention to improve a mill of this type. To this end I provide a hopper below the mill, and means for supplying gas under pressure to the hopper so that the gas flows in upward direction through the mill from the hopper.

In the drawings affixed to this specification and forming part thereof a mill embodying my invention is illustrated diagrammatically by way of example.

In'the drawings Fig. 1 is a partly sectional elevation showing a complete plant including a mill according to my invention and its gas-circulating system.

Fig. 2 is a section on the line IIII in Fig. 1. f

Referring now to the drawings, the mill illustrated by way of example is of the general construction disclosed in U. S. Letters Patent No. 1,358,837. In this mill there is a generally circular track. As particularly illustrated in the drawings, 17 is the grinding ring of the mill, 18 is its yoke, 19 are pushers on the yoke. A rotatable pul'verizing ele ment is associated with the track; thus 1 are the balls which are propelled by the pushers 19. Rotation'is imparted to the yoke 19 by means of a shaft 20 and a pulley 21. As here shown the circular track is adapted to restrain the rotatable pulverizing element radially since the grinding ring 17 completely surrounds the balls 1. X

It is understood that I am not limited to this particular type of mill, nor to the means for rotating its yoke.

A substantially horizontal member is disposed below the pulverizing element and provides openings through which fine materials grinding ring 17 which forms the grinding race for the balls 1. It will'be observed that the ring plate, here illustrated as the screen 14, is adapted to restrain the pulverizing element vertically. It lies between the pulverizing unit an dthe hopper. 12 is a material hopper below the screen, 13 is a blade at the end of an arm 22 on the boss 23 of the yoke 18 which aids in removing the material from the hopper 12, 15 is a discharge pipe at one no side of the hopper, and 24 is a blade valve which closes the discharge pipe 15 Without interfering with the outflow of the material therefrom. It will be evident that any convenient form of air-lock inay be used to per- 05 form the function of the blade valve 24 without departing from the proper scope of the present invention.

2 is a casing which is secured on top of the grinding ring 17, 25 is a cover at the upper to end of the casing, and 8 is an inverted partition which is suspendedfrom the cover 25 and extends into the casing 2, its lower end being frusto-conical. As will appear from Fig. 2 the partition 8-is slotted at 26 and 9 are flapsopposite the slots and extending tangentially with respect to the wall of the partition 8.

4 is a centrifugal fan 6 is its dischar e pipe the lower end of WhlCl'l extends into t e 30 partition 8, and 7 is' an adjustable nozzle at the lower end of the discharge pipe which I together with an opening at the lower end of the frusto-conic'al portion, constitutes a sort of injector. 11 is a branchpipe which 35 extends to the hopper 12 from the discharge pipe 6. 3 is an outflow pipe which is inserted in the cover 25, with its lower enlarged end surrounding the discharge'pipe 6 in co-axial relation. 5 is a centrifugal separator to so which the upper end of the outflow pipe 3 is connected, and 16 is the suction pipe of the fan 4 which is connected to the. separator 5 at its upper end.

In operation, the air is circulated in the system by the fan 4. A portion of the air from the delivery pipe 6 is conducted to the hopper 12 by the pipe 11, and rises through the screen 14. The hopper 12 is, therefore, also an air supply chamber. Fans 27 are as its cover 25 where it is admitted'into the partition 8 through the slots 26 while its flow is reversed and deflected tangentially'by the flaps 9, and finally is delivered to the separator 5 through the overflow pipe 3. The particles which are dropped from the mixture collect in the region of the partition 8 which surrounds the nozzle 7 where hey are entrained by the flow from the discharge pipe 6, and returned to the mill. The down ward flow at the nozzle 7 does not interfere with the upward flow along the wall of the casing as the two flows are a considerable distance apart. The fans 27 by forcing the air away from the axis of the mill generate a vacuum in its axial region which assists the injector-like action of the nozzle 7.

Heavy but fine constituents of the material; for instance the sand which is normally admixed to lignite'are separated by the screen and dropped into the hopper 12 Where they are agitated by the blade 13, and finally discharged through the pipe 15, the valve 24 preventing loss of gas. of pure lignite are entrained by the air from the hopper 12, andfinally delivered to the separator 5. Coarser particles of lignite are retained by the screen 14 until they have been ground to a suflicient degree of fineness, and are .then also entrained by the gas, as described. v v

By separating sand or other fine and heavy particles not only the purity of thefinal product is improved but also the wear of the mill is reduced. The fan 4 is also pr'otected from wear by being supplied with purified gas only through its suction pipe 16.

It will appear that the same volume of gas or air flows continuously through the system and is not made up from any outside source. This has the advantage that when treating materials which may form explosive mixtures, such as some classes of lignite, 'sulfur and the like, inert gas may be used instead of air and such gas is continuously circulated in the system without oxygen havin access to it.

stead of providing a branch pipe 11 from the discharge pipe 6 to the hopper 12, I may connect the discharge pipe 6 itself with the hopper in which case obviously the nozzle 7 is dispensed with;

' I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for 0hvious modifications will occur to a person skilled in the art.

In theclaims afiixed to this specification The fine particles no selection of any particular modificationof the invention is intended to the exclusion of other modifications thereof and the right to subsequently make claim to any modification not covered by these claims is expressly reserved.

I claim: L 1. In a pulverizing mill, a rotatable pulverizing element, a generally circular track associated therewith, a substantially horizontal member providing openings below said pulverizing element through which fine materials may flow downwardly and through which air may pass upwardly, a material hopper and air supply chamber beneath said circular track, a discharge pipe associated with said hopper, an air lock closing said discharge pipe, but permitting material to pass therethrough and a movable element in said hopper adapted to move material therein toward said discharge pipe substantially as described.

2. In a pulverizing mill a pulverizing unit, a casing above said pulverizing unit, a tubular partition in said casing carried thereby with its open end facing said pulverizing unit, a separator, a pipe line connecting said casing to said separator, a fan, a second pipe line connecting said separator to the suction side of said fan, a, collection hopper below said pulverizing unit, a discharge pipe extending from said fan into said partition so as to form an injector with its open end, and a branch pipe extending from sald discharge pipe to said hopper for carrying a current of air thereto.

3. In an air discharge pulverizing mill, a

rotatable pulverizing element, a generally.

circular track associated therewith pgsitioned to restrain said rotatable pulverizing element radially, a substantially horizontal ring plate beneath said rotatable pulverizing element adapted to.restrain said pulverizing element vertically, said ring plate having openings therein for conducting fine materials downwardly and for permitting air to pass upwardly and a collection hopper and a r supply chamber beneath said ring plate substantially as described.

4. In an air. discharge pulverizing mill, a rotatable pulverizing element, a generally circular perpendicular track associated-therewith and a substantially horizontal member supporting said rotatable element; said hori-.

zontal member having perforations therein immediately. beneath said rotatable element for conducting fine materials downwardly and for permitting air to pass upwardly to ducting fine materials downwardly and for means for rotating said pulverizing element permitting air to pass upwardly to carry off and said discharge blade substantially as define materials, a collection hopper and air i supply chamber beneath said circular track, a discharge pipe associated with said hopper and an air lock closing said discharge pipe but permitting material to pass therethrough.

6. In a pulverizing mill, a rotatable pulverizing element, a generally circular track with its race portion substantially vertically arranged, a substantially horizontal perforated member supporting said pulverizing element, drive means for rotating said pulverizing element in engagement with said track, an air outlet at the upper portion of the milland an air inlet below said perforated member, means for conducting air under pressure through the mill, a collection hopper below said perforated member, and a rotatable blade in said hopper operatively connected with said drive means.

7. Ina pulverizing mill, a rotatable pulverizing element, a generally circular track associated therewith, an air outlet above said rotatable pulverizing element, an air inlet below said rotatable pulverizing element and a substantially horizontal member support- I ing said rotatable element, said substantially horizontal member having perforations therein immediately beneath said rotatable element for conducting fine materials downwardly and for permitting air to pass upwardly to carry ofi fine materials.

8. In an air discharge pulverizing mill, a rotatable pulverizing element, a generally circular track associated therewith positioned to restrain said rotatable pulverizing element radially, a substantially horizontal ring plate beneath said rotatable pulverizing element adapted to restrain said pulverizing element vertically, said ring plate having openings therein immediately beneath said rotatable pulverizing element for conducting fine materials downwardly and for permitting air to pass upwardly, a member substantially closing the space within said ring plate, and a collection hopper and air supply chamber be neath said ring plate substantially as de scribed.

9. In an air discharge pulverizing mill, a rotatable pulverizing element, a generally circular track associated therewith positioned to restrain said rotatable pulverizing element radially, a substantially horizontal ring plate beneath said rotatable pulverizing element adapted to restrain said pulverizing element vertically, said ring. plate having openings therein immediately beneath said rotatable pulverizing element for conducting fine ma terials downwardly and for permitting air to pass upwardly, a collection hopper" and air supply chamber beneath said ring plate, a rotatable discharge blade in said hopper and Int estimony whereof I aflix m signature.

CLAUDIUS ETERS.

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