US1719831A - Two-zone pulverizing apparatus - Google Patents

Description

July 9, 1929. F. H. DANIELS TWO-ZONE PULVERIZING APPARATUS Filed April 12, 192'? P1251) H DANIELS ATTORNEY Patented July 9, 1929.

v UNITED STATES PATENT OFFICE.

FRED H. DANIELS, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO RILEY STOKER CORPORATION, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSA- CHUSETTS.

TWO-ZONE PULVERIZING APPARATUS.

Application filed April 12,

This invention relates to a pulverizing apparatus, and more particularly to a machine having two pulverizing zones, one for preliminarily crushing the coarse material, and the other for finely grinding the same.

In one form of pulverizing apparatus as heretofore constructed, the preliminary crushing operation has been efiected largely by impact, revolving swing hammers mounted within an annular perforated grid being utilized for this purpose. These prior constructions have all been subject to certain inherent disadvantages. For example, it has been found in practice that the openings in this grid tend to become plugged and obstructed, particularly when Wet materlal is being treated. thereby reducing the capacitv and etliciencv of the apparatus. Moreovcr. the Wear on the hammers and perforated grid is excessive in certain instances, and it is particularly severe if hard foreign bodies enter the machine with the coarse material and must be worn away until sufticiently small to pass through the perforations in the grid. I have discovered that for certain purposes a more satisfactory operation is obtained by providing ad acent to the path of the hammers an accumulated mass of the material being pulverized, so that the incoming material is crushed by the hammers against this accumulation. This construction has a further advantage in that it eliminates practically all possibility of damage to parts of the machine from hard foreign bodies. for if such bodies enter with the coarse material they are innn diately embedded in the comparatively soft niass outside the hammer path.

It is accordingly one object of my invention to provide a pulverizing apparatus of this type in which the preliminary crushing operation is effected largely by attrition as distinguished from impact and in which liability of damage from foreign bodies or plugging by Wet material is reduced tov the minimum.

A further object of my invention is to provide an improved means for introducing air into the preliminary crushing zone, so as to transport material to the second zone as fast as it is sufficiently crushed, and to prevent all possibility of wet material adhering to the apparatus at undesired points.

Pulverizing machines have been construct- 1927. Serial No. 133,181.

ed in which a rotor-disk, mounted to rotate about a horizontal axis, is provided to separate the pulverizing chamber into the two pulverizing zones. In such machines, coarse material thrown off by the preliminary breakers tends to accumulate in the bottom of the pulverizing chamber beneath the rotor disk. If the rotor rubs against this pile of material, excessive wear and friction on the rotor disk is caused thereby. Moreover this rubbing acts as a brake on the machine, overloading the driving motor and limiting the capacity of the pulverizer.

It is accordingly a further object of my invention to provide a pulverizing apparatus of this type in which the rotor Will be free to rotate without contact with an accumulated mass: of material.

With these and other objects in view as will be apparent to those skilled in the art, my invention resides in thecombination of parts set forth in the specification and covered oy the claims appended hereto.

In accordance with my invention, I provide a pulverizing apparatus having two pulverizing zones connected by a peripheral passage so that the material preliminarily crushed in one chamber is fed to the peripheral outer portion of the second chamber whence it is caused to pass inwardly toward a centrally disposed outlet. In my preferred construction. the two grinding zones may be formed by means of a disk-shaped rotor arranged centrally of the casing and spaced adjacent to its periphery from the casing wall so as to provide a communicating passage around its edge. A set of revolving heaters are so arranged in the second zone that material fed thereto is obliged to pass against the action of centrifugal force set up by the boaters towards a centrally disposed outlet and thus be subjected to a fine pulverization. In the first zone, I prefer to utilize revolving hammers to crush the material preliminarily, and to so arrange these hammers that they may sweep over an accumulated mass of the ma: terial being treated, the incoming material being crushed thereagainst by attrition, and hard foreign bodies being embedded therein. Suitable provision may be made for removing these foreign bodies at the convenience of the operator. The hammers are prefer-- ably pivotally mounted, so as to swing freely and yield in case a particularly hard foreign body is met. Since the material may lodge to some extent in the bottom of this preliminary crushing zone and frictionally drag against the rotor, it is preferred in such instances to provide a partition which separates the rotor from the space within the first zone thereby holding the coarse material away from its sides and permitting it to rotate freely. Moreover, it is desired that air be admitted to this casing in order that the material may be readily transported therefrom as soon as it is crushed, and while the air may be introduced with the coarse material, I preferably provide inlet openings adjacent the periphery of the preliminary crushing zone, and these are so arranged that the amount of air introduced may be varied at will. A fan serves to transport the material from the casing and to move it to a desired locality such as the burner of a furnace if fuel is the material being pulverized.

Referring to the drawings illustrating one embodiment of my invention, and in which like reference numerals indicate like parts:

Fig.1 is a vertical section substantially through the center of the apparatus, illustrated somewhat diagrammatically;

Fig. 2 is a section On the line 22 of Fig. 1;

Fig. 3 is a partial section on the line 33 of Fig. 1;

Fig. 4 is a partial section on the line 44 of Fig. 1; and

Fig. 5 is a perspective view of a rejector blade.

The embodiment of the invention illustrated in the drawings comprises a casing arranged to form a pulvcrizing chamber and a casing 12 arranged to form a fan chamber. These two chambers are connected by a passage 14 which forms a centrally located outlet for the pulverized material. A substantially disk-shaped rotor 15 is mounted within the pulverizing chamber 10. The rotor 15 is mounted on a hub 16 which is keyed to a horizontal shaft 18 mounted in suitable bearing in the casing, An inlet opening 20 for the introduction of coarse material from the chute 21 is provided in the casing wall on the opposite side of the rotor from the outlet 14. A series of revoluble swinging hammers 23 are arranged adjacent to the inlet 20 and in the path of the incoming material to initially pulverize it. These hammers 23 are illustrated as pivotally mounted by means of bolts 25 on a flanged hub 26 which is keyed to the shaft 18. As illustrated, the hammer ends are spaced from the surrounding casing wall, and such annular space communicates directly with the peripheral passage which connects the two pulverizing zones around the disk.

In order to pulverize material finel in the second zone adjacent the outlet, ar-

range revoluble impact members or pegs 28 which are mounted upon the rotor disk 15. If desired, stationary pegs 29 may be mounted upon the casing wall to cooperate with the revoluble pe s in pulverizing the material. These sets of pegs are. preferably arranged in concentric circles, and the stationary pegs are located close to the path of the revolving pegs, as.shown clearly in Fig. 3. They may be mounted in any suitable manner upon their supports, but the preferred form of mounting is fully disclosed in the patent to Riley, No. 1,576,472.

If desired, a set of substantiallly radial rejector arms may be mounted on the hub 16 and arranged to revolve within a beveled ring 36 which surrounds the outlet opening 14. These rejector arms serve to scoop out of the issuing cloud of pulverized material any coarse particles which may be present therein, and return them to the pulverizing elements for further comminution.

A suitable fan 40 is mounted on the shaft 18 within the fan chamber 12 and it is arranged to draw a current of air through the machine and force it out of a tangential outlet 41. The air may enter the pulverizing chamber with the coarse material, but in my preferred construction I provide a series of air openings in the wall of the first pulverizing zone. These openings 45 are preferably arranged, as illustrated, in the upper portion of the preliminary crushing zone and on the outside vertical wall so that they may direct a stream of air across the outer portion of the first zone and directly to the passage around the rotor, thus assisting in transporting the material which is thrown off from the revolving swing hammers into the second pulverizing zone. It is desirable to provide means for controlling the flow of air through these openings 45. Any suitable device may be arranged for this purpose, but I prefer to provide a manifold 47 which covers the openings and is provided with an adjustable butterfly damper 48. If desired, heated air may be drawn through the manifold 47 from any suitable heating device, not illustrated. The use of heated air is especially desirable when the material undergoing pulverization has a high percentage of moisture therein.

In order to prevent any accumulation of coarse material beneath the rotor disk 15 I provide a suitable partition wall or plate 50. In the embodiment illustrated, this plate 50 is arranged in a vertical plane closely adjacent to the disk 15 and between the disk and-the swing hammers 23. This plate is mounted in the lower half of the casing only and in the preferred construction it extends substantially to the horizontal center line of the machine. This plate 50 may be attached to the casing wall 10 in any suitable manner, as by means of small clip angles 51.

It is apparent from an inspection of the drawing, that this construction provides a space beneath the swing hammers 23 in which coarse material may accumulate without contact with the rotating disk. Any hard foreign bodies which enter the machine will immediately be embedded in this accumulation. If desired, a suitable slide 55 (Fig. 1) may be arranged to permit access to the' accumulated mass of material in the bottom of the machine.

The operation of the apparatus will now be apparent from the above disclosure. The shaft 18 is rotated by any suitable source of power, and coarse material is delivered to the chute 21 by any suitable feeding device. The material is crushed by the attrition action of the revolving swing hammers 23 which sweep over the mass of coarse material accumulated in the space beneath them. Any hard foreign bodies which may enter the machine are immediately embedded in this mass without causing excessive wear on the hammers. the casing is clear, and the crushed material will be thrown upwardly and caused to pass into the second zone at the top of the apparatus. Air is drawn into the machine through the openings 45 by the action of the fan 40 and this air current carries the material from the first zone around the rotor disk into the second pulverizing zone. The air from the inlets 45 passes as jets across the peripheral wall of the casing and tends to keep it clear of deposits of damp material hurled by the hammers against the wall. It is particularly desirable to preheat this air so that the heat will evaporate moisture from the fuel that tends to accumulate on the wall, thereby serving to prevent the fuel sticking to any large extent. This air may be suitably preheated, such as by connecting the inlet pipe to a passage within hollow walls of the furnace, and the temperature may be regulated as desired.

In the second zone, material is uniformly and finely pulverized by the action of the revolving impact pegs 28 and the stationary pegs 29. Fine material passes inwardly against centrifugal force towards the centrally located outlet 14 and thence into the fan casing 12 and is forced out of the outlet opening 41. Any coarse material which reaches therejector arms 35 is immediately returned to the pegs for further pulverization. There are no small openings through which the material has to pass and for this reason all danger of plugging with wet material is eliminated.

It will also be observed that the pegs 28 and 29 are relatively large and that but one row of each set of pegs is illustrated, although more than one row of either or both sets may be employed to advantage in cer- Only the upper portion of tain cases. The pegs 28 are short so that a wide clearance is provided between their ends and the casing liner plate. This leaves aspace for fine material to pass directly to the outlet without contact with the revolving beaters. The stationary pegs 29 are found to decrease the fineness of the H1- terial, apparently preventing it from remaining in contact with the beater pegs 28 for any length of time, and the degree of fineness of the produ may be adjusted depending upon the size, location and number of the stationary pegs. By having but a single row of each set of pegs, I insure a low power consumption, and in that case depend upon the rejector blades to return to the grinding members such coarse particles as may get by them.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1 A pulverizing apparatus comprising a casing havmg an inlet for coarse material and an outlet for pulverized material, means forming two peripherally communicating pulverizing zones adjacent to the inlet and outlet respectively, means to retain within the first zone and prevent its passing to the second zone an accumulated mass of material. revoluble members in the first zone arranged to sweep over this accumulated mass and crush incoming coarse material thereagainst by attrition, and revoluble impact members in the second Zone to finely pulverize material passing thereto from the first zone.

2 A pulverizing apparatus comprising a casing having an inlet and an outlet located centrally thereof, a rotor disk mounted within the casing and arranged to form two peripherally connected pulverizing zones adjacent the inlet and outlet respectively, a-

series of substantially radial revoluble hammers within the first zone for preliminarily crushing coarse material by attrition against. an accumulated mass of the material being treated, and impact members ll'lOtllltOttOI] the rotor in the second zone and arranged to finely pulverize material as it passes inwardly against centrifugal force towards the outlet.

3. A pulverizing apparatus comprising a casing having an inlet for coarse material and an outlet for pulverized material, means forming two peripherally communicating pulverizing zones adjacent the inlet and outlet respectively, means to retain an accumulated mass of material in the lower portion of the first zone and prevent its passing to the second zone, rcvoluble members in the first zone arranged to sweep over this accumulated mass and crush coarse material thereagainst by attrition, said revolublezone so to provide a space in which material may be crushed ,by repeated impacts, and means in the second zone for finely pnlverizing material.

A pulverizing apparatus comprising a 4 using, a rotor disk therein arranged to form a pulverizing zone on each side thereof which communicate adjacent to the periphery of the rotor, means in each zone to pulverize material therein, and means preventing communication between the zones adjacent to the lower portion of the rotor, whereby the preliminarily crushed material must pass to the second zone only at the upper portion of the casing.

5. A pulverizing apparatus comprising a casing, a rotor disk therein arranged to form a pulverizing zone on each side thereof which communicate outside the periphery of the rotor, means in the first zone for crushing coarse material, means'in the second zone for finely grinding material, means preventing communication between the zones adjacent to the lower portion of the rotor, and means for introducing streams of air into the upper portion of the first zone to assist in transporting the crushed material past the rotor and into the second zone.

6. A pulverizing apparatus comprising a casing having an inlet and a centrally located outlet, a rotor mounted within said casing in such a way as to form two pul verizing zones adjacent to the inlet and outlet respectively which communicate at the periphery of the rotor, a rotary beater in the first zone arrangedto preliminarily crush material delivered through said inlet, impact members on the rotor in the second zone to pulverize the material finely as' it passes to the centrally located outlet,

and means causing the preliminarily crushed material to enter the second zone only at the upper portion of the casing adjacent to the periphery of the rotor.

7. A pulverizing apparatus comprising a casing having an inlet and an outlet therein, means forming two pulverizing zones which communicate only at the top peripheral portion of the casing, revoluble means within the first zone for crushing material preliminarily, meansin the second zone for pulverizing material finely, and means for in troducing air directly into the casing adjacent to the peripheral wall thereof so as to blow the fines directly to the second zone.

8. A pulverizing apparatus comprising a casing having an inlet and a centrally 10- cated outlet, a rotary beater arranged adjacent to the inlet to crush coarse material delivered therethrough, a rotor mounted within the casing between the beater and the outlet, impact members on the rotor adjacent to the outlet for pulverizing material finely, and a partition wall in the lower part of the casing between the beater and the rotor, Said wall being located close to the rotor and so arranged as to prevent material from accumulating against the side thereof.

9. A pulverizing apparatus comprising a casing having an inlet, a rotatable substantially horizontal shaft extending into said casing, means forming an outlet for ma terial adjacent to the axis of said shaft, a partition wall within the casing and beneath the shaft, a rotary beater mounted on the shaft on the opposite side of the partition wall from the outlet, a rotor mounted on the shaft on the same side of the partition wall as the outlet, and impact members on said rotor to pulverize material finely.

10. A pulverizing apparatus comprising a casing having an inlet and a centrally located outlet, a horizontal shaft rotatably mounted within the casing, a set of revoluble yielding hammers mounted on the shaft adjacent to the inlet, a disk shaped rotor mounted on the shaft between the hammers and the outlet, r'evoluble impact members onthe outlet side of said rotor, stationary impact members on the casing wall adjacent to said revoluble impact members, and a partition wall in the lower part of the casing between the hammers and the disk and close to the disk.

11. A pulverizing apparatus comprising a casing having an inlet and an outlet located centrally thereof, a horizontal shaft rotatably mounted within said casing, a set of hammers pivotally mounted on centers spaced from the axis of the shaft and arranged to revolve adjacent the inlet, a disk shaped rotor mounted on the shaft so as to form a second pulverizing zone adjacent the outlet, a partition wall in the lower part of the casing between the hammers and the disk and close to the disk, revoluble impact members on the rotor in the second zone, stationary impact members on the casing wall in the second zone, and a rejector device to prevent the passage of coarse material through said outlet.

Signed at \Vorcester, Mass, this 8th day of April, 1927.

FRED H. DANIELS.

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