US2359911A - Pulverizer - Google Patents

Description

Oct. 10, 1944. GRINDLE 2,359,911

PULVERIZER Filed Oct. 1, 1941 3 Sheets-Sheet 2 Oct. 10, 1944. J N LE 2,359,911

PULVERI ZER Filed Oct. 1, 1941 3 Sheets-Sheet 3 Tvolmzw Patented Oct. 10, 1944 UNITED STATES PATENT OFFICE PULVERIZER Aubrey J. Grindle, Chicago, 111.

Application October 1, 1941, Serial No. 413,093

26 Claims.

The present invention relates to improvements in pulverizers, and has particular reference to new and improved means for producing comminuted or powdered material, such as coal, adapted to be supplied in a stream of air directly to combustion apparatus or to be placed in storage.

It is an object of the invention to provide a new and improved pulverizer of the above-mentioned general type which is characterized by simplicity of construction, ease of manufacture, installation and use, efliciency and economy of operation, and extreme efiectiveness in the production of pulverized material below a particular predetermined fineness or particle size.

Another object is to provide, in a pulverizer of the above-mentioned general type, a novel air flow circuit and coal feed and delivery arrangement in which all of the air, both primary and secondary, and the fuel enters and leaves the unit through or adjacent the base thereof to simplify and expedite plant installation and operation.

In connection with the foregoing, it is an object of the invention to provide a novel air fiow circuit in which air is introduced through the base of the pulverizing unit to effect cooling, the flow being divided to supply a secondary air propeller on the one hand and a primary air circuit on the other, the latter flow being introduced under high velocity into the pulverizing zone to entrain comminuted particles, thence through a separator from which the fuel laden air is directed downwardly through the center of the pulverizing unit and, finally, discharged at the base for delivery to a burner or storage space.

Another object resides in the provision of novel means for preventing the entraimnent and discharge with the particle laden air, of particles above a predetermined fineness, including new and improved means for returning the oversize particles to the crushing zone.

A still further object of the invention is to provide a novel stator construction for the pulverizing area including new and improved li'ner units adapted for easy insertion and removal, and being designed so that, by reversal or adjustment, a plurality of new cutting surfaces may be presented to accommodate wear.

A further object of the invention is to provide a novel rotor construction for the pulverizer unit, including a new and improved hammer and hammer-mounting arrangement designed for easy installation and replacement and in which the hammers are pivotally supported at their inner ends for radial extension under the influence of centrifugal force for cooperation with the stator.

A further object of the invention is to provide in a pulverizer new and improved means for facilitating the recirculation of air through the pulverizer after the comminuted material has been removed therefrom for storage.

Other objects and advantages will become apparent as the following description proceeds, taken in connection with the accompanying drawings, in which:

Figure 1 is a side elevational view of a pulverizing apparatus embodying the features of my invention.

Fig. 2 is a horizontal sectional view on an enlarged scale in the plane of the line 22 of Fi 1.

Fig. 3 is a vertical sectional view of the pulverizer taken in the plane of the line 3-3 0 Fig. 2.

Fig. 4 is a perspective view of certain details of the rotor-hammer construction prior to assembly.

Fig. 5 is a fragmentary vertical sectional view similar to Fig. 3 on an enlarged scale and illustrating an alternative form of rotor construction.

While the invention is susceptible Of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiments, but it is to be understood that I do not thereby intend to limit the invention to the specific forms disclosed but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring more particularly to the drawings, the pulverizer constituting the exemplary embodiment of the invention is adapted primarily for comminuting solid fuel, such for example as coal, to produce what is commonly known in the trade as "powdered coal. Despite this primary use, however, it is to be understood that the apparatus of the instant invention is admirably well suited for pulverizing a wide variety of materials among which 'cement, chalk, talc, cocoa, face and tooth powders may be mentioned as illustrative. The apparatus is adapted also to supply comminuted fuel in intimate suspension in a stream of air, to a burner for immediate consumption, or alternatively to storage means wherein the air is separated from the powdered fuel, the latter being stored in bulk.

The apparatus selected for illustration (see Fig. 1) comprises in general a hopper It for receiving fuel to be pulverized, a coal feeder II for feeding coal to a pulverizer unit I2, preferably of the vertical type, and a suitable blower or propeller I3 (Fig. 3) for creating a stream of primary air having a. substantial velocity and adapted to entrain granules of fuel of a predetermined fineness from the pulverlzing unit I2. A second blower or propeller I4 may be provided for creating a stream of secondary air, preferably adjustable in volume in accordance with the combustion requirements. In the preferred embodiment illustrated, the blowers I3 and I4 and the pulverizing unit I2 are driven by a single vertical shaft I5 common to all and connected at the top to a suitable source of power, such as an electric motor I6.

The pulverizer (see Figs. 1 and 3) has an outer housing consisting of superimposed housing sections II, I8, I9 and 20. The upper three housing sections I8, I9 and 20 are preferably generally circular in horizontal cross section, as illustrated in Fig. 2. The base housing I! is hollow and extends laterally from the circular housings to support the coal feeding mechanism II and the hopper I0. The-lowermost circular housing section I8 encloses a bearing housing 2I for the lower end of the shaft I5 and is open at its bottom for communication with the base housing I! upon which it is supported. The intermediate housing section I3, which rests on the section I8, encloses the primary blower I3 within an inner housing 22, and encloses also the pulverizing unit I2. This intermediate housing I9 has a bottom wall 23 which closes the top of the housing section I3 and supports the bearing housing 2| for the shaft I5 which extends through a central aperture formed therein. The top housing section 20 encloses the secondary air propeller I4, an upper shaft bearing housing 25 for the shaft I5 and a power transmission device 26 for transmitting power from the motor I6 to the shaft. The top housing 20 rests on, and has a bottom wall 21 closin the top of the intermediate section I9. A division plate 28 divides the housing 20 into two compartments, the lower for the propeller I4 and the upper for the transmission 26, and conveniently supports the bearing housing 25. At the top, the housing section 20 is closed by a plate 29 which is formed on its upper side to adjustably mount the motor I6, as by means indicated at 30.

The shaft I5 extends centrally through the pulverizer housings and forms a component part of the pulverizing unit I2 and the blowers or propellers I3 and I4. At the bottom, the shaft is supported in anti-friction bearings 30 of the radial and end-thrust type which are mounted in a sleeve 3I rigid with the bottom wall 23 and within the housing 2I. Suitable packing 32 is provided between the shaft I5 and the bottom wall 23 to close the bearing housing 2I against the entrance of foreign matter. vision is made for lubricating and cooling the bearings 30 and to this end cool oil may be introduced into the housing 2I.

The upper end portion of the shaft I 5 is journaled in anti-friction bearings 33 supported in the upper bearing housing 25 which projects into the casing 20. The upper end of the housing 25 is closed by a cover 34 apertured to receive the shaft I5 therethrough, and provided with suitable oil retainer 35. The division plate 28 is apertured centrally to receive the shaft I5 through suitable Packing 36. Means forming no Desirably propart of the present invention, and accordingly not illustrated herein, may be provided for supplying cooling and lubricating oil to the housing 25. For distributing the oil to the bearings 33 an annular flange 31 rigid with the bearing housing 25 is formed about the central aperture in the division plate 28 and projects upwardly to above the normal oil level in the bearing housing 25. An annular oil flinger 38 is secured to the shaft I5 for rotation therewith and projects downwardly and outwardly about the flange 31 into the body of oil and tends to throw oil upwardly.

In the present instance an inner housing 39 is provided for the propeller I4 and spaced downwardly from the division plate 28. An air inlet 40 in the periphery of the housing 20 opens to the interior thereof between the division plate 28 and the housing 39. An azmular inlet H in the housing 39 around the shaft I5 permits air to flow to the impeller I4. Preferably, the top housing 20 is provided with an air inlet opening 42 opening in its peripheral wall to the atmosphere, and communicating with the interior of the housing 20 adjacent the power transmitting device 26. The division plate 28 has a plurality of small openings 43 closely adjacent the bearing housing 25 for the free passage of air from the atmosphere through the upper housing 20 and into the space below the division plate 28 which houses the propeller I4. It will be evident that the element I4 will cause the flow of a small stream of cooling air from the atmossphere into the casing 20 and about the transmission 26 and bearing housing.

The pulverizer unit I2 (see Figs. 2, 3 and 4) comprises a rotary hammer construction mounted on the shaft I5 for rotation therewith, and an encircling stationary liner construction. In

40 the preferred form, the rotary hammer construction consists of a rotor keyed, as at 56, to the shaft I5 within the housing I9. The rotor herein comprises inner and outer concentric sleeves 51 and 58, respectively, rigidly mounted with respect to each other by a plurality of radially extending struts or pins 53 and vanes extending between the sleeves within the space formed between them. A pair of axially spaced annular plates 6| and 62 are fixed to the outer sleeve 58 and project radially therefrom to support a set of hammers 63 and a set of plows 64 below the hammers. In the present instance, six hammers and six plows are provided, the hammers being pivotally mounted for arcuate swinging movement about their inner ends, the centrifugal force imparted by rotation of the rotor in operation causing the hammers to project radially outwardly for cooperation with the liner construction.

Each hammer preferably includes a pulverizing head 65 at its outer end (Fig. 4), a supporting boss 66 at its inner end and an intermediate shank portion 61 interconnecting the head and boss. A pivot pin 68, projecting through coaxially-alined holes 69 and III in the plates 6I and 62, respectively, and through an aperture tion by the pivot pin 68 which is held against rotation by frictional engagement with the walls of the holes 69 and I8 and which extends through an aperture 14 formed in the inner end of the shank 13. The inner edge of the aperture 14 has a fiat face 15 adapted to seat in an inwardly offset keyway 16 formed in the pivot pin, and to this end the aperture 14 is enlarged to permit insertion of the pin and radial outward movement of the plow to seat the flat face 15 within the keyway 16. A depending lug 11 formed on the rear of the hammer boss is adapted to cooperate with the rear face of the shank 13 in assembly to hold the plow in its outward, locked position.

In assembling the parts, the hole I4 in the shank of the plow is registered with the hole 18 in the lower plate 62, the hammer boss is superimposed on the plow shank to register the hole Ii therein with the hole 69 in the upper plate GI and with the hole 14 in the plow shank. In this assembly operation, the hammer is inserted with its longitudinal extent substantially tangent to the rotor, in which position the lug 11 on the hammer is at one side of theplow shank so that the plow may be moved radially inwardly to register the holes and permit insertion of the pin 88. The pin is then inserted through the registered holes, the plow is moved radially outwardly to locked position, and the hammer is swung to its radial, outwardly-projecting position in which the lug l1 cooperates with the rear of the plow shank to hold it locked. During operation, the hammers tend to seek a radial, outwardlyprojecting position and thereby prevent displacement of the plows which are rigidly held in radially extending position.

The liner structure or stator encircles and coacts with the set of hammers 63 and plows 64 and defines therewith a crushing zone closed at the bottom by an annular plate 18. The plate may be secured to the inner periphery of the housing I9 to extend radially inwardly below the hammer structure to a point radially spaced from the bottom of the external sleeve 58 of the rotor. The space between the sleeve 58. and the inner periphery of the annular plate 18 thus provides a central annular air inlet 19 to the crushing zone. The space below the annular plate 18 and above the housing 22 for the primary air impeller l3 forms an air -passage having an air inlet 89 formed in the peripheral wall of the housing section I9, and leading to the central annular inlet 19.

The liner structure or stator preferably comprises a series of identical liner units which may be turned end-for-end and side-for-side to accommodate wear caused by the pulverizing operation. In its preferred form, the construction comprises a plurality of individual liner units 8| (Fig. 4) which may be inserted, one at a time, through oppositely disposed doors 82 (Fig. 2) of the housing l9 and slid peripherally around the inner wall of the housing i9 on which they are supported to form a peripherally contiguous stator structure. In the form illustrated (Fig. 4), each liner unit comprises a pair of symmetrical impact bars 83 rigidly interconnected by end pieces 84. The end pieces are slidably received in tracks formed, as by a p f annular in s 85 spaced inwardly of the peripheral wall of the housing and secured to the plates 21 and I8, respectively, which define the top and bottom of the crushing zone. It will be seen that each of the impact bars is elongated in form to extend throughout the height of the crushing zone between the plates 21 and 28 and has symmetrical longitudinal faces on its opposite sides, substantially one-half of each face traversing the active crushing area through which the hammers 83 operate. By virtue of the foregoing construction, it will be apparent that the impact bars or liner units may be turned, from their first position shown, end-for-end to present a second unwom surface to the hammers and again reversed side-for-side to present a third unwom surface from which position the units may be again reversed end-for-end to present a fourth unworn surface.

The coal or fuel to be powdered is introduced through one side of the housing section l9, and is adapted to be acted upon by the hammers 63, in cooperation with the liner, members 8|. Thus, the housing section I9 (Fig. 2) has a fuel inlet opening 86 in one side slightly above the plane of the hammers 63 and at which point the liner units are discontinued. A duct 81 communicates with the opening 88 tangentially of the housing and may be connected to any suitable source of material tobe powdered such, for example, as the fuel feeder ll (Figs. 1 and 2).

In the present instance, the hopper I8 is mounted on a base 88 with which the duct 81 communicates. Extending through the hopper base and the duct 81 is a conveyor screw 89 for discharging material to the pulverizer. The screw 89 has a shaft 98 which may be driven from any suitable source of power and which is herein shown drivingly connected through speed reduction gearing 9! to an electric motor 92.

One of the primary features of the feeder is the construction of the conveyor screw 89, first, so that clogging of fuel is prevented and, second, to provide an even distribution of fuel to the pulverizer. Thus, the intake end of the screw is provided with a relatively small external circle of revolution, as indicated at 93, becoming progressively larger toward the center 94 of the screw and again diminishing toward the discharge end 95 to a relatively small circle of revolution. By virtue of the small circle of revolution at the intake end becoming progressively larger toward the center, overloading of the conveyor screw is prevented, and by virtue of the progressive reduction of the external circle of revolution of the conveyor screw from its center toward its discharge end, any tendency of the fuel to become compacted in mass accumulations is prevented. The progressive reduction or taper toward the discharge end breaks up accumulations which might otherwise be discharged in adhering masses to the pulverizing zone causing an uneven feed and a consequent variation in output. The present construction assures a uniform feed to the pulverizer at all times.

The peripheral wall of the housing section [9 at the opening 88 is provided also with a tangential pocket 96 formed, in the present instance, as a continuation of the duct 81 and adapted to receive heavy foreign matter, such as tramp iron. The tramp iron pocket is thus formed directly opposite the conveyor screw on a line tangent to the peripheral wall of the housing I9. The pocket terminates in a downwardly projecting outlet 91 normally closed by a removable cover 98 through which tramp iron collecting in the pocket may be removed. It will be evident that foreign matter and tramp iron introduced by the conveyor screw will be directed into the tangential pocket 96 immediately upon contact with the rapidly rotating hammers 63 before it is carried around the pulverizing zone. Thus undue wear of the liners and hammers caused by tramp iron is prevented.

One of the important features of the present invention is the air flow circuit. The pulverizer is so designed as to cause the air to flow first through the base of the machine so as to prevent the transmission of heat from a furnace or oven flue, upon which the pulverizer may be mounted, to the working parts. The air flow from the base of the machine is then divided into two streams, one for the secondary air propeller I4 and the other for the pulverizing unit I2 and primary air propeller I3. The latter stream is caused to flow radially inwardly substantially to the center of the pulverizer. The stream is then directed radially outwardly at a high velocity along the floor or bottom of the pulverizing area and upwardly about and around the pulverizing elements, to pick up and entrain finely comminuted particles of fuel. At the top of the pulverizing unit this stream passes through a centrifugal separator which segregates fuel particles above a predetermined fineness for return to the pulverizing zone. Thereafter, the fuel laden air is directed radially inwardly and thence downwardly through an annular air passage in the center of the pulverizer to the blower I3 from which primary air, carrying the finely comminuted particles, is ejected through the base of the machine for immediate use in a burner or, alternatively, for storage.

To this end (see Figs. 1 and 3), the hollow base housing I1 is formed at its left-hand end remote from the pulverizer with a bottom air inlet I communicating with the atmosphere. Formed in the side of the lower cylindrical housing section I8, which communicates with the base housing I1, is an outlet IOI communicating with an external duct I02. The duct I02 directs air from the outlet IN to the air intake openings 40 and 80 formed, respectively, near the bottom of the housing sections 20 and I9 respectively. In this manner, all of the air supply, both primary and secondary, enters through the base of the apparatus to effect cooling thereof and is directed through the duct I02 to the primary and secondary circuits.

The primary air entering through the inlet 80 in the housing I9 is directed radially inwardly to the central annular inlet I9 to the bottom of the pulverizing zone. An annular ring I 01 is mounted on the upper side and at the inner peripheral edge of the plate I8, and cooperates with the lower plate 52 of the rotor to define a restricted air inlet which directs the air flow radially outwardly along the bottom of the crushing zone at a high velocity. After passing across the floor of the pulverizing zone, the air is caused to flow upwardly about and between the-hammers 63 and liners 8| to the top of the housing I9. In passing through the crushing zone, the air entrains all particles of pulverized fuel, the high velocity radial stream at the bottom of the zone preventing accumulations and the plows 64 tending to force the larger particles into the crushms area.

In the instant embodiment, I have provided a centrifugal separator at the top of the crushing zone and in the path of travel of the fuel laden air for preventing substantially all partlaesaeii cles of fuel above a predetermined particle size from passing from the crushing zone. Preferably, this separator comprises a plurality of uniformly, peripherally spaced vanes or blades I08 rigid with and extending radially from the upper plate 6| of the rotor. The upper edge of each vane is inclined upwardly and outwardly over a portion of its length so that the centrifugal action imparted thereby to the fuel air stream increases upwardly. The coal laden air tends to pass upwardly between the plates and radially inwardly to an annular central opening I05 in the top of the rotor, and hence is subjected to a swirling action and to centrifugal force. The heavier fuel particles are thrown outwardly and drop back into the crushing zone, only those of a predetermined fineness or less passing to the annular air passage I06 in the rotor. To Prevent the fuel from jumping over the vanes I08, 8. depending annular flange I09 is formed on the underside of the top plate 21 in concentricallyspaced relation about the opening I06 in the rotor.

The annular space between the spaced concentric sleeves 51 and 58 of the rotor provides an air passage communicating at its lower end with the housing 22 for the primary air impeller I3. After passing through the separator, the fuel laden air passes downwardly through this annular air passage. In the present instance, I have provided in the air passage, in addition to the struts 59, the set of four evenly-spaced, radially-extending vanes 60 inclined to the vertical to facilitate and insure the rapid passage of fuel laden air to the impeller. By virtue of this construction, accumulations of fuel in the passage are prevented.

Between the lower end of the rotor and the top of the housing 22 into which it is slightly telescoped, a wobble plate I03 circumscribes the outer sleeve 58 of the rotor and is yieldably secured to the housing 22 to seal the connection. Thus, machine bolts I04 extending through holes I05 in the plate I03 having large clearance, are screw-threaded in the housing 22, and through the agency of compression springs 99 yieldably maintain the plate I03 in position.

The blower I3 may be of any suitable form, and is shown in the drawings as a radial bladefan keyed to the shaft I5 for rotation within the housing 22. The hub of the fan is keyed to the shaft I5 and the packing 32 between the hub and the bottom plate 23 prevents the passage of fuel laden air through and into the housin 2|. The impeller housing section 22 has a peripheral air outlet III passing through the housing I 9 and which may be connected to a storage bin (not shown) or a burner (not shown). It will be understood that the primary air stream enters the housing I 9 through the opening 00 and fuel laden air is discharged through the outlet I ll.

The propeller I3 serves to induce a constant flow of high velocity air through the pulverizer unit. when the outlet II is connected to a burner, the blower I3 thus supplies a substantially constant volume of primary air, regardless of adjustments of the ultimate fuel air ratio or of the kind of fuel supplied to the pulverizer. The propeller I4, which provides secondary air, is supplied through the inlet 40 at one 'side of the bottom of the housing section 20 which communicates with the duct I02. The secondary air stream passes to the propeller I4 through the inlet ll in the housing 33 and includes a small stream of cooling air which flows through the opening 42 in the top housing 20 and theopenlugs 43 in the division plate 28. This propeller I4 is in the form of a radial blade-fan keyed to the shaft I5 for rotation within the housing 39. The housing 39 has a peripherally tangential air outlet H6 which passes through the wall of the housing 20 for connection to a burner.

Referring more particularly to'Fig. 5, I have illustrated therein an alternative form of rotor construction. It is desirable under certain conditions to produce comminuted particles of extreme fineness and to control the degree of particle fineness with great accuracy. To this end, I have provided a rotor structure generally similar in design to that heretofore disclosed, but incorporating means for producing a more finely comminuted product and for completely removing any particles above a predetermined fineness from the material laden air as it passes downwardly through the rotor, and returning these particles to the crushing zone. In this form, the stream passing downwardly through the annular air passage in the rotor is subjected to centrifugal action, causing all particles above a predetermined fineness to be thrown outwardly, the passage being provided with peripheral openings for the return of oversize particles to the crushing zone for further reduction in particle size. A further feature of this embodiment is the provision of means for facilitating the recirculation o'f the entraining air, after the particles have been separated from the stream for storage.

In the preferred embodiment of this construction, an inner sleeve I20, concentric with the drive shaft I5 and keyed for rotation therewith, as at I2I, extends throughout the height of the pulverizing compartment. In concentricallyspaced relation to substantially the lower onethird of the inner sleeve I20, is an outer sleeve I22 rigidly secured with respect to the inner sleeve. The axially extending annular passage thus formed between the sleeves, communicates at its lower end with the blower I3 and at its upper end with a separator. The separator is rigid with the upper portion of the inner sleeve I20 for rotation therewith, and the particle laden air, after passing through the crushing zone, is directed downwardly through the separator and thence to the blower I3 between the sleeves I20 and I22. Preferably, the separator comprises a plurality of axially spaced cones, in the present instance two I24 and I25), arranged in concentric spaced relation to the sleeve I20 and rigidly secured with respect thereto by a plurality of radially extending vanes I26 and I26. Rigid with the lower cone I25 and extending radially outwardly therefrom is an annular plate I21 spaced amally from the lower edge of the upper cone I24 and providing therewith a peripheral outlet from the separator to the crushing zone. At the top of the outer sleeve I22, a second annular plate I28 axially spaced from the plate I21 provides with the sleeve a similar peripheral outlet below the lower edge of the lower cone I25.

As in the first described rotor construction, particle laden air is directed downwardly through the top opening in the rotor construction, in the present instance defined by the upper cone I24. As the stream passes downwardly between the upper cone I24 and the sleeve I20 andinto the axially-extending, peripherally-arranged passageways formed by the cones I24 and I25, the

vanes I28 and I20 and by the inner sleeve I20 it is thereby subjected to a swirling action. The particle laden air tends to pass downwardly to the passage formed between the lower portion of the sleeve I20 and the outer sleeve I22. The heavier fuel particles are thrown outwardly by centrifugal force, passing out through the peripheral outlets formed below the lower edges of the cones I24 and I25 to the crushing zone, only particles of a predetermined fineness being allowed to pass downwardly under the influence of the blower I3.

Since the centrifugal force is dependent in part on the radius of the circle of revolution of the vanes I26 and I26, the size of the selected particles may be varied by extending or diminishing the radial extent of the cones and vanes, and to some extent, by the inclination of the cones. This adjustment may be accomplished by substituting rotors having the desired radial blade extent and cone inclination for the particular installation. If blades of greater width are substituted, the entrained material leaving the pulverizer unit will be relatively finer. If the efl'ective throw of the blades is reduced, the entrained material will be relatively coarse. Preferably, the axially-spaced annular plates I21 and I28 are arranged to carry a set of hammers 63 of the general type described in connection with Figs. 2 and 3.

The particle laden air is delivered by the blower I3 to stora means (not shown) wherein the air is separated from the comminuted material for recirculation through the pulverizer. To this end an inlet opening I30 is formed adjacent the bottom of the housing I9 communicating with a passageway I3I which extends radially inwardly between the blower housing 22 and the bottom plate 18 of the pulverizing zone. The recirculated air enters the pulverizing area centrally thereof between the annular plate I28 and the annular ring I01. To prevent the accumulation of particles incompletely removed from the recirculated air, a plurality of fiingers I32 are formed rigidly on, and in peripherally-spaced relation about, the lower end of the outer sleeve I22. The fiingers project radially outwardly into the path of travel of the entering stream of air and adjacent the top wall of the blower housing 22 which defines the bottom of the air passage I3I. Thus, any particles tending to accumulate, and which might otherwise clog the passage, are subjected to a swirling action and thrown into the path of travel of the entering stream of air.

The air entering the pulverizing unit under high velocity and in a somewhat turbulent condition, sweeps the bottom of the pulverizing zone to entrain pulverized particles. Passing upwardly through the active crushing zone, the stream becomes laden with particles and in passing downwardly through the separator, all particles above a predetermined fineness are segregated.

It will be apparent from a consideration of the foregoing that I have provided a pulverizer which is simple and inexpensive in construction; adapted for ready assembly, dismantling and repair, and which is extremely effective and efiicient in operation. Material to be pulverized is fed to the unit smoothly and evenly, tramp iron and other foreign material are removed instantaneously before they are introduced to the crushing zone. The particle laden air is subjected to an eflicient separating action which returns oversized particles to the crushing zone,

assuring a stream having particles of uniform fineness below a predetermined particle size.

The pulverizer as a whole has a desirable arrangement and design from the standpoint of plant installation, since all material, both air and fuel, is introduced to and ejected from the base of the unit. The rotor and stator constructions are particularly advantageous by virtue of my novel hammer and plow mounting construction rendering their replacement a relatively simple operation, and by virtue of my novel liner units which may be reversed and adjusted to accommodate wear.

I claim as my invention:

1, In a fuel pulverizer, in combination, a housing, a rotor and a stator defining a crushing zone within said housing, means for introducing fuel to said crushing zone, means defining an air inlet to the bottom of said crushing zone,

' means defining an axially extending annular air passage within said rotor communicating at its upper end with the top of said crushing zone and having an outlet at. its lower end, means for creating an air fiow from said air inlet upwardly through the crushing zone to entrain comminuted particles of fuel and thence downwardly through said annular air passage to said outlet, and means for driving said rotor.

2. In a pulverizer, in combination, an external housing, a rotor and a stator defining a crushing zone within said external housing, means for introducing fuel to said crushing zone, means defining an air inlet to said crushing zone, a second housing within said external housing, means defining an axially extending central air passage in said rotor communicating at one end with said crushing zone and at its other end with said second housing, an air impeller in said second housing, means defining an air outlet passage from said second housing, means for driving said rotor, and means for driving said air impeller to cause a fiow of air from said air inlet through said pulverizing zone and thence through said axially extending passage to said impeller and finally to said outlet passage.

3. In a pulverizer, in combination, an external housing, an internal housing within and at the bottom of said external housing, a. rotor and a stator on a vertical axis defining a crushing zone within said external housing above said internal housing, means defining an air inlet to said external housing communicating with the lower part of said zone, means for introducing material to be pulverized to said crushing zone, means defining an axially extending central air passage in said rotor communicating at its upper end with the upper portion of said housing above said crushing zone and at its lower end with said internal housing, means defining an air outlet passage from said internal housing through said external housing, means for driving said rotor, an air impeller within said internal housing, and means for driving said air impeller to cause a flow of air from said air in let upwardly through said pulverizing zone and thence downwardly through said axially extending passage to said impeller and finally to said outlet passage.

4. In a puverizer, in combination, a pulverizing unit having a generally cylindrical housing with top and bottom walls, an air inlet opening to the bottom of said housing, an internal housing at the bottom of said external housing, an intermediate wall spaced above said internal housing with a centralv air inlet, a stator and a rotor on a vertical axis defining a crushing zone above and outwardly beyond said central air inlet, means for introducing material to said external housing in substantially the plane of said rotor, a vertical shaft for driving said rotor and extending centrally through said top and bottom walls and said central inlet opening, an impeller on said shaft within said internal housing, means within said rotor defining an axially extending air passage communicating at its upper end with the upper portion of said external housing and at its lower end with said internal housing, and means defining an air outlet from said internal housing through said external housing.

5. In a pulverizer, in combination, a housing. a rotor and a stator defining a crushing zone within said housing, means for introducing material to said crushing zone, means for driving said rotor, means defining an air inlet to the bottom of said crushing zone, means defining an axially extending annular air passage within said rotor having an upper outlet at the top of said crushing zone and having a lower outlet at the bottom of said rotor, means for creating an air fiow from said air inlet upwardly through the crushing zone to entrain comminuted particles and thence downwardly through said annular air passage to said lower outlet, and means in the path of travel of the particle laden air for separating therefrom particles above a predetermined fineness and for returning said particles to the crushing zone.

6. In a pulverizer, in combination, a housing. a rotor and stator defining a crushing zone within said housing, means for introducing material to i be pulverized to said crushing zone, means for driving said rotor, means defining an air inlet to the bottom of said crushing zone, means defining an axially extending air passage within said rotor communicating at its upper end with said housing above said crushing zone and having an outlet at its lower end, means for creating an air fiow from said air inlet upwardly through the crushing zone to entrain comminuted particles and thence downwardly through said central air passage to said outlet, and means carried by said rotor and disposed in the path of travel of the particle laden air for separating therefrom and returning to the pulverizing zone particles above a predetermined fineness.

7. In a pulverizer, in combination, a housing, a rotor and a stator defining a crushing zone within said housing, means for introducing material to said crushing zone, means for driving said rotor, means defining an air inlet to the bottom of said crushing zone, means defining an axially extending air passage within said rotor communicatingat its upper end with said housing above said crushing zone and having an outlet at its lower end, means for creating an air fiow from said air inlet upwardly through the crushing zone to entrain comminuted particles of material and thence downwardly through said central air passage to said outlet, and means carried by said rotor for subjecting the particle laden air to centrifugal force to separate therefrom and return to the pulverizing zone particles above a predetermined fineness.

8. In a fuel pulverizer, in combination, a housing, a rotor and stator defining a crushing zone within said housing, means for introducing material to said crushing zone, means for driving said rotor, means defining an air inlet to the bottom of said crushing zone, means defining an axially extending air passage within said rotor communicating at its upper end with said housing above said crushing zone and having an outlet at its lower end, means for creating an air flow from said air inlet upwardly through the crushing zone to entrain comminuted particles of material and thence downwardly through 'said central air passage tosaid outlet, and a plurality of radially disposed blades fixed in spaced relation on. said rotor and disposed in the path of travel of the particle laden air for separating therefrom and returning to the pulverizing zone particles of fuel above a, predetermined fineness, said blades having an external circle of revolution increasing progressively in the direction of travel of the particle laden air.

9. In a pulverizer, in combination, a housing, a rotor and a stator defining a crushing zone within said housing, means for introducing material to be pulverized to said crushing zone, means for driving said rotor, means defining an air inlet to the bottom of said crushing zone, means defining an axially extending annular air passage within said rotor communicating at its upper end with the top of said crushing zone and having an outlet at its lower end, said last named means being formed to provide peripheral outlet openings from said passage to the crushing zone, means for creating an air fiow from said air inlet upwardly through the crushing zone to entrain comminuted particles and thence downwardly through said annular air passage to said outlet, and means in said passage for subjecting the particle laden air passing downwardly there-.

through to centrifugal action to efiect separation of particles above a predetermined size and return thereof through said peripheral outlet openings to said zone.

10. In a pulverizer, in combination, a housing, a rotor and a stator disposed on a vertical axis and defining a crushing zone within said housing, means for introducing material to said crushing zone, means defining an air inlet to the bottom of said crushing zone, a plurality of radially extending blades arranged peripherally of said rotor, the external circle of revolution of said blades increasing progressively downwardly, means closing only the upper portions of the the outer edges of said blades to define an annular air passage extending axially of said rotor and communicating at its upper end with said housing above said crushing zone, said passage having a progressively increasing external circle of revolution toward the bottom of said blades, means defining a straight continuation of said passage below said blades, means defining a peripheral outlet at the bottom of said blades communicating with said crushing zone, means for creating a fiow of air from said inlet upwardly through said crushing zone and thence downwardly through said passage, and means for driving said rotor to pulverize said material and to subject the particle laden air passing downwardly through said passage to centrifugal force to separate and return to the crushing zone through said peripheral outlet particles above a predetermined size.

11. In a pulverizer, in combination, a rotor and a stator disposed on a vertical axis and defining a crushing zone having an enclosing housing, means for rotating said rotor, means defining an axially extending annular air passage downwardly through said rotor communicating at its upper end with the upper portion of said crushing zone and having an outlet at its lower end, means for causing a stream of air flow upwardly through said crushing zone and thence downwardly through said annular air passage, means defining axially spaced peripheral outlets in said passage, and a plurality of blades mounted in said passage for subjecting the particle laden air passing downwardly through said passage to centrifugal 'force whereby to eject particles above a predetermined fineness radially outwardly through said peripheral openings to said crushing zone.

12. In a pulverizer, in combination, a housing, a stator mounted on the inner periphery of said housing, a rotor joumaled in said housing and having impact means adapted for cooperation with said stator and defining therewith a crushing zone, means for introducing material to be pulverized to said crushing zone, said housing having an air inlet opening to the bottom of said crushing zone, said rotor having formed therein an axially extending annular air passage communicating at its upper end with said housing above said crushing zone and having an outlet at its lower end, a centrifugal separator formed in the upper portion of said passage and having a peripheral outlet communicating with said crushing zone, means for causing air to flow upwardly through said crushing zone and thence downwardly through said separator and passage to said outlet, and means for driving said rotor.

13. In a pulverizer, in combination, a generally cylindrical housing, a stator mounted on the inner periphery of said housing, a rotor journaled in said housing and having impact means adapted for cooperation with said stator and defining therewith a crushing zone,;means for introducing material to be pulverized to said crushing zone, means defining an air inlet at the bottom of said crushing zone, said rotor having an annular passage communicating at its upper end with said housing above said crushing zone and having an outlet at its lower end, a centrifugal separator mounted on said rotor within the upper portion of said passage, said separator having an external circle of revolution progressively increasing downwardly and a peripheral outlet at its lower end communicating with said crushing zone, means for creating a fiow of air from said inlet upwardly through said crushing zone and thence downwardly through said separator and passage, and means for driving said rotor.

14. In a pulverizer, in combination, a housing, a stator and a rotor on a, vertical axis defining a crushing zone within said housing; means for introducing material to be pulverized to said zone, a bottom air inlet to said zone, means defining an axially extending annular air passage centrally of said rotor communicating at its upper end with the upper part of said external housing and having an outlet at its lower end, means for creating an air flow from said bottom air inlet upwardly through the crushing zone to entrain comminuted particles and thence downwardly through said annular air passage,

- means defining axially spaced, peripherally disposed annular air outlets from said annular air passage to the crushing zone, means within said annular air passage for imparting a swirling motion to the particle laden air passing downwardly therethrough to return to said crushing zone by centrifugal force all particles in said air above a predetermined fineness, and means for driving said rotor and the air fiow creating means.

15. In a pulverizer, in combination, a housing,

a rotor and a stator defining a crushing zone within said housing, means for introducing material to be pulverized to said crushing zone, means for driving said rotor, means defining. a bottom air inlet to said crushing zone, said rotor having formed therein a central axially extending air passage communicating at its upper end with said housing above and radially inwardly of said crushing zone and having an outlet at its lower end, means for creating an air fiow from said air inlet upwardly through the crushing zone and thence radially inwardly to said passage and downwardly therethrough to said outlet, a plurality of radially extending blades arranged pe ripherally of said rotor above said crushing zone in the path of travel of particle laden air for subjecting said air to centrifugal force to separate therefrom particles above a predetermined size.

16. In a pulverizer, in combination, an external housing, a rotor and a stator defining a crushing zone within said housing, means for introducing material to said crushing zone, said housing having an air inlet Opening to the bottom of said crushing zone, an internal housing at the bottom of said external housing, said rotor having an axially extending annular air passage formed therein communicating at its upper end with said external housing above said crushing zone and with said internal housing at its lower end. a plurality of radially extending vanes peripherally arranged in said passage and inclined to facilitate air flow downwardly through said passage upon rotation of said rotor, an impeller in said internal housing, means for driving said impeller to create an air flow from said air inlet upwardly through the crushing zone and thence downwardly through said passage to said impeller, and means for driving said rotor.

17. In a pulverizer, in combination, a hollow base having an opening therein communicating with the atmosphere, an external housing supported on said base, a rotor and a stator defining a crushing zone within said housing, means for introducing material to said crushing zone, means defining an air inlet to the bottom of said crushing zone, an internal housing in the bottom of said external housing, means defining an axially extending air passage within said rotor communicating at its upper end with the top of said crushing zone and at its lower end with said internal housing, means for directing air from said hollow base to said air inlet, an impeller within said internal housing for creating an air flow from said inlet upwardly through the crushing zone and thence downwardly through said ar passage to said internal housing, means for driving said impeller, and means for driving said rotor.

18. In a pulverizer, in combination, a hollow base having an opening therein communicating with the atmosphere, a generally cylindrical housing on said base having top and bottom walls, and two intermediate transverse walls dividing said housing into three compartments, a primary air impeller in the bottom compartment, a secondary air impeller in the top compartment having an intake opening, a rotor and a stator in the center compartment on a vertical axis between said impellers and defining a crushing zone, a central axially extending air passage formed in said rotor, a vertical shaft extending centrally through said top and bottom walls for driving said rotor and impellers, means for in troducing material to said crushing zone, an air inlet near the bottom of said crushing zone,

means for directing air from said hollow base to said intake opening for said secondary air impeller and to said air inlet, and means for directing a stream of air from said inlet upwardly through said crushing zone and thence downwardly through said passage to said primary air impeller.

19. In a pulverizer, in combination, a pulverizing unit having a rotor and a stator on a vertical axis defining a crushing zone and having an enclosing housing in support of said stator, said stator including a plurality of separate liner members, track means supporting said liner members for sliding movement peripherally around the inside of said housing, a door in said housing for the insertion of said members whereby said members may be mounted on said track individually and moved around the inside of said housing to form a peripherally contiguous stator structure, each of said liner members being formed symmetrically end-for-end and side-forside whereby upon reversal thereof end-for-end and side-for-side four separate wearing faces maybe presented to said rotor, means for feeding material to be pulverized to said zone, and means for removing pulverized material from said zone.

20. In a pulverizer, in combination, a housing, a rotor disposed on a vertical axis within said housing, a complementary stator enclosed in said housing, a plurality of hammers pivotally mounted at their inner ends on said rotor and adapted for radial extension therefrom under the influence of centrifugal force, means defining a central axially extending annular air passage through said rotor, and means for causing a flow of air upwardly through said crushing zone to entrain comminuted particles and thence downwardly through said passage.

21. In a pulverizer, in combination, a pulverizing unit having a rotor and a stator on a vertical axis defining a crushing zone and having an enclosing housing, a vertical shaft supporting said rotor and journaled for rotation centrally of said housing, a plurality of crushing hammers supported on said rotor for extension radially thereof for cooperation with said stator, a plurality of plows carried on said rotor below said hammers, means including a pivot pin supporting each of said hammers for arcuate swinging movement about its inner end and supporting the inner end of each of said plows, means on said hammer coacting with said pivot pins to hold the plows rigidly extended radially of said rotor, means for supplying material to be pulverized to said crushing zone, and means for causing a stream of air to pass through said zone to entrain comminuted particles.

22'. In a pulverizer, in combination, a pulverizing unit having a rotor and a stator defining a crushing zone and having an enclosing housing, a shaft supporting said rotor and jorrnaled for rotation in said housing, a plurality of crushing hammers extending radially of said rotor for cooperation with said stator, a plurality of plows supported on said rotor, a pivot pin carried by said rotor and adapted to pivotally support each of said hammers on said rotor for arcuate swinging movement about its inner end, a loose connection between the inner ends of said plows and the pivot pins to facilitate assembly of the parts and adapted to be taken up to maintain said plows in rigid radially-extended relation with respect to said rotor, and means on said hammers for cooperation with said plows and adapted during assembly to take up said loose connection and maintain such relationship during operation.

23. In a pulverizer, in combination, a pulverizing unit having a stator and an enclosing housing, a rotor journaled for rotation in said housing, said rotor including a plurality of crushing hammers and a plurality of plows below said hammers, a pivot pin carried by said rotor for pivotally supporting each of said hammers for arcuate swinging movement about its inner end, said hammers being adapted upon rotation of said rotor to extend radially thereof under the influence of centrifugal force for cooperation with said stator, each of said plows having an aperture at its inner end to receive said pivot pin therethrough, said aperture providing a loose connection between each plow and pivot pin, the connections being adapted to be taken up during assembly to maintain said plows in rigid radially-extending relation with respect to said rotor, and means on said hammers adapted in assembly to maintain such relationship during normal operation of the pulverizer.

24. In a pulverizer, in combination, an external housing, an internal housing within and to the bottom of said external housing, means including a rotor defining a crushing zone within said external housing and above said internal housing, an air intake in the peripheral wall of said external housing, a division plate defining the bottom of said crushing zone and having a central inlet opening, said plate being spaced above the top of said internal housing to provide a passageway from said air intake to said inlet opening, and a plurality of flingers carried by said rotor and disposed adjacent the bottom of said passageway to prevent the accumulation of particles therein.

25. In a pulverizer, in combination, a housing defining a pair of chambers arranged in vertically spaced relation, the upper of said chambers having an opening in its bottom wall, pulverizing mechanism disposed in the upper chamber, means defining a passage extending from the upper end of said upper chamber through said opening to the lower chamber, and a blower mounted in said lower chamber operative to induce the flow of air through said opening upwardly around the pulverizing mechanism in said upper chamber and thence downwardly through said passage to said lower chamber, said lower chamber having an outlet for the air. 26. In a pulverizer, in combination, a housing, coacting rotatable and stationary members in said housing defining a crushing zone, said housing having an air inlet opening adjacent the bottom of said zone, means defining an air passage extending downwardly entirely through said zone and communicating with the upper portion thereof, a blower operative to induce a flow of air through said inlet opening upwardly around said members and thence downwardly through said passage, and means for driving said rotatable member and said blower.

AUBREY J. GRINDLE.

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