US2487088A - Jet impact pulverizer - Google Patents

Description

4 N. H. ANDREWS v JET IMPACT PULVERIZER Filed July 19, 1944 I5 Sheets-Sheet 1 F G U R E INVENTOR NORWOOD H. ANDREWS.

Nov. 8, 1949 N. H. ANDREWS JET IMPACT PULVERIZER s She ets-Sheet 2 Filed July 19, 1944 HGURE- 2' NORWOOD H. ANDREWS INVENTOR N. H. ANDREWS JET IMPACT PULVERIZER Nov. 8, 1949 Filed July 19, 1944 3 Sheets-Sheet 3 FIGURE lNV ENTOR NORWOOD H. ANDREWS.

. from ten to twelve per Patented Nov. 8, 1949 2,487,088 JET IMPACT PULVERIZER Norwood H. Andrews. Moorestown, N. 1., asslgnor,

by mesne assignments,

pany, New York, N. Y.,

ware

The Micronizer Coma corporation of Dela- Application July 19, 1944, Serial No. 545,667 11 Claims. (Cl. 241-40) This invention relates to an apparatus for reducing the particle size of partially comminutcd solids. It is concerned with equipment for grinding solids which may contain adsorbed or absorbed water and is advantageously applied to finely pulverizing anthracite culm, clay, paint pigments and other similar materials.

The following will illustrate a typical application of my improved apparatus. In screenings from anthracite workings there are literally millions of tons of material available which are called anthracite culm in the industry. This culm ordinarily contains about thirty per cent of ash and cannot satisfactorily be burned on grates until it is treated to reduce the ash content to at least ten per cent. This can be accomplished by a flotation separation, but the fraction of reduced ash content then carries cent of water. Attempts to dry such potential fuel result in a considerable loss, due to the carrying out of the fines in the drying air stream, as well as exceeding costs permissible in the preparation of a fuel. Attempts to dry the culm by methods other than passing a heated gas over or through it have met with little success due to the difficulty in such other methods of handling the large quantities of materials usually present.

Likewise, there are many situations in other industries requiring the reduction in size of solid particles from either a wet or a dry, original state. Processing earth materials, such as various clays, processing paint or ink pigments, and processing paper coating materials are examples of industries having these requirements. These illustrations will suggest others.

I have now devised asimple apparatus having no moving parts whereby particles of solids, such as those named. can be reduced in size from that in which the solids are originally obtained. Furthermore, the apparatus is capable of using a wet materialfsuch as washed culm, directly without the necessity of first drying carefully.

It is accordingly among the objects of the invention to provide an apparatus for treating partially comminuted solids, containing insuflicient water to produce a slurry, which apparatus will yield a dry, finely divided, product in uniform size ranges.

It is a further object of the invention to provide apparatus which is capable of grinding, drying, and classifying partially comminuted solids in which no moving parts are required.

Another object of the invention is to provide n apparatus for grinding anthracite ca m and 2 other solids containing adsorbed water which economically produces a uniformly sized, finely divided product.

Still a further object of the invention is to provide an apparatus capable of handling large quantities of relatively coarse solids in a short time cycle and with equipment having a high throughput in pounds per hour per square foot of drying, grinding and classifying area.

In the drawings:

' Figure 1 illustrates diagrammatically, in side section elevation, a preferred form of apparatus in which my invention may be practiced. Figures 2 and 3 illustrate diagrammatically, in side section, elevation alternative forms of apparatus in which my invention may be practiced.

The method which I have invented includes feeding the solid (wet or dry) at a fairly uniform rate to an aspirating zone from which it enters into a high velocity gas jet or jets. The gas is preferably heated where drying is to be accomplished but otherwise heating is not essential.

The solid particles are then projected by the gas stream against a suitable blockor anvil upon which they are shattered. The gas stream, carrying the said particles, is then led out of the impact zone and introduced tangentially into a classifying zone surrounding the path of introduction of the solid into the high-pressure gas. In the classifying zone the particles of the solid which have been reduced to the desired size are carried out of the zone and particles larger than the desired size drop out of the gas stream and downward into the raw feed, thus returning such oversize particles to the high-pressure gas stream and subjecting them to further processing.

The particular series of steps which comprise my invention include:

Releasing a' gas under high pressure through an orifice to create a high velocity flowing gas stream; introducing solid to be ground into a high velocity gas jet in an aspirating zone; interposing a block in the path of the high velocity material-laden gas stream in a confined zone to cause the solid to be reduced in size; discharging gas and solid from said confined impact zone to a classifying zone through a relatively constricted passageway to cause translation of pressure energy in the confined impact zone to velocity in said classifying zone; and, returning particles above predetermined size ranges from said classifying zone to the said aspirating zone.

The apparatus for carrying out the method -just described may comprise a generally cylin- 1 .16% ele siiying chamber near the bottom of which the solid feed is aspirated into a high velocity gas jet or jets and carried out of the chamber to an impact anvil located within a confined space. From said confined space a passageway leads back to the classifying chamber and enters same near its top, directed tangentially therelnto, providing entry of ground solid suspended in the gas stream. The upper portion of the chamber serves as a classifying section in which particles larger than predetermined size ranges are rejected from the vortically flowing gas stream and return to the bottom Of the chamber to be picked up again by the aspirator.

Figure 1 shows diagrammatically, in side elevation, an apparatus wherein the invention may be practised. Referring to said figure, washed wet solid I is fed from a conical bottom hopper H through a star feeder l2 into a vertically disposed tube l3 projecting well into a cylindrical classifying and separating chamber M. An inlet pipe I 5 is connected to a source of gas such as superheated steam or compressed air under superatmospheric pressure, which source is preferably at a point outside the classifying chamber I. Said pipe I5 is centrally located in the feed tube l3 and projects downwardly through the feed tube l3 to a point near the conically shaped bottom l6 of the classifying chamber It. The gas inlet pipe l5 terminates in a nozzle H, which, for convenience, may be threadediy engaged with the end of the pipe I5. The conical bottom iii of the classifying chamber I4 is attached to a connecting pipe i8 projecting into an impact chamber l9 which directs the gas against an anvil which is preferably removable for replacement. Said anvil is made from any hard and abrasion resisting material and has its impact surface perpendicular to the axis of the connecting pipe l8. A passageway 2! serves to carry gas and particles of the solid from the impact chamber l9 and return the same tangentially into the classifying chamber It. The passageway 2| leads into the classifying chamber it near the upper portion thereof, and enters the same approximately tangentially. An annularly disposed baiile 22 having a circular up-standing lip 23 is arranged in the classifying chamber l4 immediately below the point at which the-passageway 2! from the impact zone i9 is attached to the upper part of the classifying chamber l4.

An off-take pipe 24 from the top of the chamber i4 is provided to carry gas and particles of the .desired size from the chamber l4 and discharges into a suitable cyclone separator (not shown) or other receiving means. The off-take pipe 24 is concentrically disposed with respect to the feeder tube l3 and projects into the chamber I4 so that its tip 25 is in approximately the same horizontal plane as the upper edge of the lip 23 on the annular bailie 22 in the classifying chamber ll.

In operation, solid, either wet or dry, is fed at a substantially uniform rate by a star feeder I2 into the feeding tube i3 and falls freely through said tube and the classifying chamber M to the bottom thereof, at which point it is aspirated by high-pressure gas flowing out of the nozzle l1 and is hurled violently against the anvil 20 in the impact zone IS. The gas and shattered particles then move out of the impact zone I9 through the passageway 2| and into the upper portion of the classifying chamber It. The introduction of said gas tangentially into the chamber l4 induces a circulation of the reduced particles in the chamber, causing the particles of larger size to l4 and flow around the tip 25 of the off-take pipe 24 and thence out into a cyclone separator.

The following example illustrates the practice of the invention with anthracite culm. A feed rate of 1100 pounds per hour of coal, containing approximately ten per cent by weight of water, was maintained into the separating chamber of the apparatus just described. The star feeder, carrying six paddles, was rotated at a speed of thirty revolutions per minute. Steam under pressure of pounds and at a temperature of 750 F. was introduced into the apparatus at the rate of 2000 pounds per hour. A screen analysis Of the feed was: Less than 1% through a 100 mesh and all through a 16 mesh.- The temperature of the coal after grinding was 350-375 F. The screen analysis of the product showed 96% through a 325 mesh screen, 98 through a 200 mesh, and only a trace on 100 mesh screen.- The product gave entirely satisfactory results in use as a powdered fuel for a boiler.

Figures 2 and 3 illustrate modifications which may be made in the apparatus by which the above-disclosed process is practiced.

In Figure 2 the parts 00,, l2, l3, I4, ll. 22,

23, 24, and 25 are all the same as above described for the embodiment illustrated in Figure 1. The impact chamber l9a, corresponding to chamber I9 in Figure 1, is here located concentrically within classifying chamber ll. It has a feed opening 26 in its bottom and a tubular feed member l8a which is likewise concentric with the classifying chamber l4 extending therethrough. Said tubular member I8a is flared at its lower end 21 to aid in the aspirating of solid particles into the gas stream. The anvil 20a is located within the impact chamber l9a on the side thereof opposite the feed opening 23 and has its impact surface located perpendicularly to the axis of feed tube l8a. Said impact chamber l9a may advantageously have a conical top 28 for convenience in preventing solid particles from piling thereon. A passageway 2la extends from impact chamber l9a out through the wall of the classifying chamber l4 and then reenters same throughan opening which may be constricted at the upper end thereof, in the same manner as illustrated and described for the embodiment shown in Figure 1.

A gas conduit l5a is connected to a source of gas at superatmospheric pressure, which gas is preferably dry and heated. This conduit enters through the bottom of the classifying chamber l4 and terminates in a nozzle 29 which is suitably spaced from the flared portion 21 of the feeder tube lBa for maximum aspirating effect in view of the size of the particular device, material being handled, pressure available, and other related factors, all of which are well known and understood.

The operation of this embodiment follows exactly the same principles as above described for the embodiment shown in Figure 1, and, since this operation will be entirely understandable by reference to the description presented in onnection with Figure 1 and inspection of Figure 2, further detailed description will be omitted;

In the embodiment shown in Figure 3 the prln ace-mes ilb, carries them into the impact chamber lib,

and hurls them against an anvil 20b. The continuing flow of gas carries the shattered particles out through a passageway 2lb directed into the upper portion of the classifying chamber II.

N This figure also illustrates a modification in the classification means which is applicable to all three forms. It is more efficient for certain matlrials and comprises narrowing the classification chamber id and eliminating the baffle 22 and lip 23 tobrovide the classification means as shown in said figure.

However, the general manner of operation is unchanged in that the classifying chamber, drops out the oversize particles during its downward movement and then moves upwardly through the middle of said chamber carrying the finely pulverized material and goes out through the off -take pipe 24 as before.

Various methods of feeding may be employed and various kinds of apparatus can be devised which will hurl the particles of solid at high velocity against the anvil, collect and classify the product thereof and return the oversized one to the raw feed for reprocessing. These various modifications will, however, all be within the scope of my invention both as a process and apparatus except as the otherwise.

Having thus fully disclosed and described my improved process and apparatus, I claim:

I 1. In apparatus for pulverizing solids, the combination of: a classifying chamber, a centrally disposed feeder tube ber, and means to introduce a wet solid to be pulverized into said feeder tube; a pipe within said feeder tube and extending beyond the projection of said feeder tube to a point near the bottom of said chamber for introducing a gas under superatmospheric pressure; a tube communicating from the bottom of said chamber with an impact chamber; an anvil in said impact chamber located to be struck by gas under. pressure from said classifying chamber; a passageway from said impact chamber communicating with said classifying chamber and tangentially directed thereinto in the upper portion thereof; and, an offtake pipe from said classifying chamber.

2. In apparatus for pulverizing solids, the combination of: a classifying chamber, a centrally disposed feeder tube extending into said chamber, and means to introduce a wet solid to be pulverized into said feeder tube; a pipe within said feeder tube and extending beyond the pro jection of said feeder tube to a point near the bottom of said chamber for introducing a gas under superatmospheric pressure; a tube communicating from the bottom of said chamber with an impact chamber; an anvil in said impact chamber located to be struck by gas under pressure from said classifying chamber; a passageway from said impact. chamber communicating with said classifying chamber and tangentially directed thereinto in the upper portion thereof; an annular baffle plate having an upstanding lip located within said classifying chamber below the point of tangential introduction of fluid and solid extending into said chamclaims specifically limit thereinto; an offtalre pipe concentrically arranged with respect'to said annular baile plate and adjacent said lip.

3. In apparatus for pulverizing partially comminuted solids a combination of: an independent impact chamber; an anvil within said chamber; means to introduce a gas under pressure into said chamber and arranged to direct said gas against said anvil; means to introduce the particles to be pulverized into said gas stream; a separating chamber; a closed conduit providing passageway from said impact chamber for leading all the gas and solidparticles carried therein tangentially into the upper portion of said separating chamber; an annularly disposed baiiie in said separating chamber having an up-standing lip disposed immediately below the passageway from the impact chamber at its point of entry into the separating chamber; a centrally disposed oiftake from said separating chamber; means providing communication from the bottom of the said separating chamber to the pointof introduction of the solid feed into the gas stream flowing to the impact chamber.

4. Apparatus for pulverizing a granulated solid, in wet or dry condition comprising in combination: a classifying chamber; adjustable means gravitationally feeding said solid centrally into said chamber at a substantially uniform rate; tubular means providing communication from the bottom of said classifying chamber to an inde-, pendent and enclosed impact chamber; an anvil in said impact chamber positioned therein diametrically from said communicating means and having its face surface substantially perpendicular to the axis of said tubular communication means; a nozzled conduit entering said classifying chamber positioned with its nozzle adjacent and co-axial with the said tubular means; a means supplying dry gas to said nozzled vconduit at a relatively high pressure; a closed conduit forming a passageway providing restricted communication between. and leading all the gas and entrained material from, said impact chamber to the upper portion of said classifying chamber and entering tangentially thereinto; an annular baiile within said classifying chamber located adjacent the lower edge of said last-named conduit at its point of entry into said chamber partially restricting communication between the upper and lower portions of said classifying chamber and a continuous up-standing lip at the inner most edge of said baffle forming a cylinder coaxial with said chamber; outlet means from said classifying chamber co-axial with and of less diameter than said cylinder.

5. Apparatus for pulverizing a granulated solid in wet or dry condition comprising in combination: a classifying chamber; adjustable means gravitationally feeding said solid centrally into said chamber at a substant' ally uniform rate; an impact chamber located within said first chamber and co-axial therewith; means providing communication from said classifying chamber into said impact chamber; an anvil in said impact chamber positioned therein diametrically from said communication means and having its impact surface perpendicular to the axis of said communication means; a nozzled conduit connected with a source of .dry gas under superatmosphcric pressure and entering said classifying chamber; with its nozzle positioned adjacent said communication means and co-axial therewith; a passageway providing restricted communication from said impact chamber to the upper portion of said classifying chamber and entering tangentially thereinto; an annular baffie within said classifying chamber located ad- Jacent the lower edge of said passageway at its point of reentry thereinto partially restricting communication between the upper and lower portions of said classifying chamber and having a continuous upstanding lip at its innermost edge forming a cylinder co-axialwith said chamber; outlet means co-axial with and of less diameter than said cylinder, beginning approximately in the same horizontal plane with the upper end of said lip and communicating with receiving means.

6. Apparatus for pulverizing a solid comprising in combination: a cylindrical classifying chamber; means for feeding said solid into said chamber; an enclosed impact chamber having an opening therein on one side thereof and an anvil therein on the opposite side thereof; a conduit connected to a source of dry gas at superatmospheric pressure positioned in line with said opening and perpendicular to said anvil and terminating at a point spaced from said opening for providing a gas stream; means for introducing the heavies of the classified solids from the classifying chamber into said gas stream; a single tubular passageway of uniform cross section and perpendicular to the opening in said impact chamber for transporting all of the gas and entrained material from said impact chamber tangentially entering said classifying chamber; outlet means co-axial with and of lesser diameter than said classifying chamber.

7. An apparatus for pulverizing solid particles comprising: a chamber having a circular classifying zone and a feeding zone, an independent enclosed impact chamber, means for releasing a gas under pressure through an orifice to create a high velocity flowing gas stream having an as pirating zone in said feeding zone, a conduit ex-' tending at least part way through said classifying zone, means for introducing material to be ground thereinto, said conduit passing said material through at least a part of said classifying I zone but separated then therefrom and discharging it for free falling through the rest of said classifying zone into the aspirating zone whereby said material is introduced into the gas stream in said aspirating zone, means for interposing a block in the path of the high velocity materialladen gas stream in said independent enclosed impact zone, a tubular passagewav tangentially entering said classifyingzone for discharging the gas and entrained material from said independent impact zone to a point in said classifying zone opposite a portion of said conduit for translating pressure in the impact zone to rotational velocity in the classifying zone, said parts being arranged for returning particles above a predetermined size range from said classifying zone to the aspirating zone, and discharging from the classifying zone gas and entrained particles below said predetermined size.

8. An apparatus for pulverizing a granulated solid comprising in combination: a cyclone chamber having a classifying zone at its upper end and a material collection zone at its lower end; a feeding conduit substantially concentric with and extending into and partially through said cyclone chamber, means for feeding said solid into said conduit; an independent impact chamber having an opening therein and an anvil within said chamber positioned oppositely to and co-axial with said opening; a conduit connected to a source of gas at super atmospheric pressure,

form cross-section throughout its length providing communication from'said impact chamber to the upper portion of said cyclone chamber at a point therein opposite a portion of the feeding conduit; a substantially annular outlet means coaxial with said feeding conduit and providing venting from said cyclone chamber beginning at a point above the discharge end of said feeding conduit.

9. An apparatus for pulverizing solid particles comprising: a circular cyclone chamber having a classifying zone in its upper portion and a material collection zone in its lower portion each in open communication with the other, tubular vertical means for introducing solid material thereinto extending centrally into and at least partially through the classifying zone in said cyclone chamber, an independent enclosed impact chamber exterior of said cyclone chamber containing an anvil, a conduit conducting a stream of gas under pressure into said impact chamber and directed against said anvil, said gas stream having an aspirating zone adjacent said impact chamber and at the bottom of the material collection zone, a single closed passageway of uniform cross-section throughout its length providing the only ofitake and only means of venting gas and entrained material from said impact chamber to said classifying zone, said passageway entering said classifying zone tangentially and substantially above the discharge opening of said material introducing means, all so constructed and arranged that both the raw and insufliciently pulverized material enter the material collection zone and thereby said aspirating zone by gravity from said classifying chamber, an annular venting means surrounding and substantially concentric with said material feeding means extending into the classifier a portion of the length of said feeding means.

10. Apparatus for pulverizing a granulated solid comprising in combination: a classifying cham-- her having a material collection zone at its lower end; means for feeding said solid into said chamber at a substantially uniform rate; an independent impact chamber exterior of said classifying chamber having an opening therein and an anvil within said impact chamber positioned oppositely to said opening; a conduit perpendicular to said anvil connected to a source of dry gas at superatmospheric pressure, terminatingat a point spaced from said opening and 'co-' axial therewith for providing a gas stream; means for providing open communication from said collection zone to said gas stream for effecting continuous gravitational passage of said solid from said collection zone to said gas stream and introduction thereinto; a passageway substantially perpendicular to the axis of said opening for leading all the gas and entrained material from saidimpact chamber to the upper portion of said classifying chamber; outlet means co-axial with the classifying chamber and providing venting from the upper portion of said classifying chamber.

11. An apparatus for pulverizing solid particles comprising: a circular classifying chamber, means introducing solid material thereinto extending vertically and centrally into and partially through said classifying chamber, an independent enclosed impact chamber substantially in the center of said classifying chamber and containing an anvil, a tubular member extending into said impact chamber perpendicular to and coaxial with said anvil; a nozzle coaxial with said tubular member for directing a stream of gas under pressure through said tubular member into said impact chamber, a single enclosed passageway of uniform cross section throughout its length for providing the only ofltake and the only means of venting gas and entrained material from said impact chamber to said classifying chamber, said passageway entering said classifying chamber tangentially and substantially above the discharge opening of said material introducing means, said gas stream adjacent said impact chamber having an aspirating zone at the bottom of and in open communication with said classifying chamber, said parts so arranged that both the raw and the insufliciently pulverized material will fail by gravity directly into the aspirating zone. NORWOOD H. ANDREWS.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Marks June 6, 1911 McKeivey Dec. 23, 1919 Davis Feb. 19, 1924 Arrowood May 10, 1927 Kramer Feb. 23, 1932 Kollbohm Feb. 23, 1932 Hadsel Apr. 19, 1932 Anger Aug. 30, 1932 Walton Sept. 6, 1932 Wohlenberg Oct. 18, 1932 Peabody Aug. 8. 1933 Anger Mar. 2, 1937 Chesler Mar. 30, 1943 FOREIGN PATENTS Country Date Great Britain July 19, 1937 Germany Nov. '7, 1929 Germany Aug. 23, 1930 Germany Jan. 10, 1933

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