US1921166A - Pulverizer - Google Patents

Description

1933- Q E. H. PEABODY 1,921,166

PULVERIZER Filed Oct. 24, 1950 3 Sheets-Sheet 1 W INVENTOR.

/A; A rromvs s.

1933: v E. H. PEABODY 1,923,166

- PULVERIZER Filed Oct. 24, 1930 3 Sheets-Sheet 2 W INENTOR.

.M. ATTORNEYS.

Patented Aug. 8, 1933 UNITED STATES PATENT OFFICE Peabody Engineering Corporation, New York,

N. Y., a Corporation of New York Application October 24,

6 Claims.

This invention relates to a method of and apparatus for pulverizing material in which eddy currents are set up in a moving body of air, or other gas, carrying in suspension particles of the material to be pulverized, whereby such particles are caused to come into contact with each other and with the walls of the conduit through which they are passing and thereby reduced in size either through the agency of attrition or impact, or both.

The object of the invention may be effectively carried out in various ways as by a pulverizer having therein a plurality of bafile members so arranged that when the air, or other gas, holding in suspension the material to be pulverized, is forced therethrough, the material will be compelled to take a tortuous or circuitous path around and between said members. The impact and attrition of the particles against themselves and the members will pulverize the material to various degrees of fineness.

Another object of the invention is to pulverize material carried in a gas current, within confined spaces, and to then deliver the entire mass to a separator wherein the usable fines will be carried ofi through a delivery pipe and the particles which have not been reduced to the required fineness will'be collected to be again run through the pulverizer.

The invention in its broadest aspect is directed to a method wherein the material to be pulverized is passed through a chamber of such shape as to set up eddy currents without the use of baffie members, and in the present application is shown apparatus for practicing the invention both with and without baflle members for securing the desired fiow of the material therethrough.

Although designed more particularly for pul- 40 verizing coal for feeding to a furnace, the invention is capable of general application to the pulverizing of other materials. Also, while air would be the ordinary or usual medium for carrying the material through the apparatus, any other suitable gas may be employed for this purpose. For convenience of description, however, the method will be described as one for pulverizing coal and the utilization of air as the carrying medium.

The invention will be understood by reference to the following description taken in connection with the accompanying drawings in which Fig. 1 is an elevation of an assembled apparatus partly in section and'some of the parts broken away; Fig. 2, a similar view of another assembly in 1930. Serial No. 491,007

which the pulverizer is provided with baflle members as in Fig. 1; and Fig. 3 is a similar view of an assembly wherein the pulverizer contains'no baflle members.

Referring to Fig. 1, the numeral 1 designates a pulverizer which, in the form shown, is tubular and of suitable length and diameter. The pulverization may be facilitated by baffle members which may be fixed or loose in the tube. If loose I may use pieces of scrap metal, stone or other material 2. These are placed promiscuously and may be irregular in size and shape. The prime consideration is that they shall be so disposed as to furnish a plurality of tortuous passages from the inlet to the outlet of the tube so as to permit the flow through the tube of the carrier air and material.

To prevent clogging of the passages the tube 1 is supported so that it may be continuously or intermittently rotated by any suitable means, as gears or rollers. As shown, the tube has collars 3 fitted thereon to provide bearing surfaces for rollers 4 mounted on a shaft 5 supported in a fixed frame or cradle 6. At its lower end the shaft 5 carries a bevel gear '7 which meshes with a similar gear on the shaft of a motor 8. When the shaft and rollers are rotated, the frictional engagement of the latter with the collars'3 will rotate tube 1 and thereby tumble the loose members 2 upon one another and thus clear the passages between them of any accumulated material. The rotation of tube 1 is not for pulverizing but only to prevent the passages between the bafiie members becoming clogged. When mounted in this way the tube is supported axially by a thrust bearing and bracket 9. Doors 10 are provided to permit access to the tube for filling or removal of the baflle members.

The material to be pulverized is delivered to tube 1 by anysuitable means. As here shown, it is delivered from a hopper 11 constituting the bottom or lower part of a separator housing which will be described later. Extending through the base of the hopper is a screw conveyor 12 operated by a motor 13 through suitable gearing. The conveyor discharges the material through a chute 14 into a connecting pipe 15 where it meets a current of air under pressure delivered through a nozzle 16 from a fan 17, or other source.

The material suspended in the carrier air is conveyed through pipe 10' to the inlet of tube 1. As the material is forced through the tube 1 in tortuous or circuitous paths, it'will be reduced to the desired fineness by the impact of the particles against the baflle members 2, and by the attrition of the particles upon themselves caused by eddy currents.

To the outlet of tube 1 is connected a pipe 18 through which the pulverized material is conveyed to a storage bin or separator or otherwise disposed of as may be desired.

With a material such as coal, it may be desirable to give it a preliminary crushing or grinding before it is deposited in the hopper 11. For this purpose I construct a housing 19 of suitable form and proportions so as to have the hopper 11 in the lower part thereof. Mounted upon this housing is a crusher 20 of any approved type fitted with a hopper 20 to which the material is delivered. After being crushed the material passes through a hopper 21 to a screw conveyor 22 driven by a motor 23 and suitable gearing. The conveyor discharges the coal through a chute 24 into the upper part of the housing 19, which will be hereafter referred to as a separator, inasmuch as in the chamber provided by the housing 19 the usable fines are separated and conveyed away from the particles which have not been reduced to the desired fineness. f

To effect the separation of the usable fines from the coarser particles the outlet 18 of pipe 18 from the pulverizer enters the separator tangentially to the wall thereof. Thus a whirling motion s imparted to the mass so that the centrifugal force set up throws the heavier particles toward the wall of the separator leaving the finer particles free to be drawn into pipe 25 through which they are conveyed to any desired point.

The separator housing may be made air tight so as to maintain therein suflicient air pressure to cause a current to fiow out through pipe 25. The intake of said pipe may be, if necessary, enlarged, as shown, to provide an area proportioned to the volume of air passing out through the pipe, so that the Velocity of the air entering pipe 25 will be suflicient to carry off the usable fines only, and will permit the heavier particles to settle in hopper 11 in the lower part ofthe separator.

The intake of pipe 25 may be located below the plane of outlet 18', as shown. This, however, is not essential as the separation of the usable fines from the coarser particles will result if the intake of pipe 25 is located above the plane of said outlet. The essential thing is to set up a current of air having the requiredvelocity to effect the separation, preferably near the center of the vortex. This will of necessity cause the usable fines to be conveyed away through pipe 25 while at the same time the non-usable particles will be allowed to settle in hopper 11.

If desired, an exhauster may be connected to pipe 25 and so arranged as to draw the air, laden with the fine particles, from the separator and deliver them to the point of use, or as may be desired. separator may be below or equal to that of the surrounding atmosphere.

The mass of material to be pulverized may be crushed to any desired degree of fineness and as this mass falls into the separator through chute 24 it will be taken up by the current of air admitted through opening 18 and be given a whirling motion. Should there be any usable fines in this mass they will be carried out through pipe 25 with the fines in the mass coming from the pulverizer, while the heavier particles, which constitute a very large percentage of the crushed mass, are thrown out toward the wall of the In such case the pressure within the separator with the heavier particles delivered through pipe 18, and will settle with such particles in hopper 11.

Chute 24 is preferably so set that it will deliver the crushed mass near the wall of the separator, or at least in such position, that the falling mass will clear the conveyor pipe 25. The falling mass will thus not contact with said pipe but will be free to be acted upon by the whirling current of air set up by reason of the tangential opening 18'.

While it is considered desirable to introduce the material first'into the separator and thereafter through feeder 12 and chute 14 into the pipe 15, it may, if desired, be delivered directly into pipe 15 from an outside source.

In Fig. 2 is shown an assembly in which the baffle members are in the form of balls 26 which may be of metal or other suitable material. The interstices between these bafiles provide a plurality of passages. When the material to be treated is forced through the pulverizer by the current of air under pressure from fan 17, it will be pulverized in the manner described with reference to Fig. 1 and discharged through pipe 18 into'the separator where the usable fines are withdrawn through pipe 25, while the heavier particles settle in hopper 11 to be again passed through the pulverizer.

Instead of the crusher shown in Fig. 1, the material to be pulverized, particularly if such material is coal, may be first treated in a mill of the impact type. For such purpose a motor 27 is mounted on the separator housing. To the shaft of said motor is secured a plurality of arms 28 11 hammers and by being thrown by the hammers 1 against a liner 34 enclosed within the upper part of the separator. The entire mass falls by gravity from the impact mill into the carrier air entering from the pulverizer through tangential inlet 18. The falling mass will be taken up and given a whirling motion'by such carrier air and such of it as has not been reduced to a fineness which will permit it to be carried. away through pipe 25 will settle in hopper 11 from which it will be delivered by screw conveyor 12 to be forced through pulverizer 1 and reduced therein as before explained.

The object of the invention being to set up eddy currents in the carrier air, any method of securing this effect may be utilized. Thus it is possible to drive the air laden material at high velocity through a straight pipe of relatively small diameter, or through a pipe so formed as to present sudden bends or turns to provide a tortuous path for the air. By such means suflicient turbulent motion will be created to cause the particles to contact with each other, and with the walls of the pipe, and thus through impact forces, or ata straight tube 35 This is of relatively small diameter so that as :the carrier air fiows through .trition, or both, effect a reduction in the size of it the particles in suspension will be more or less retarded byfr'ictional engagement with the wall of the pipe and by reason thereof, and the more rapid travel of the center of the mass, sufiicient turbulence will be created to produce the desired reduction.

Aside from the pipe 35 the other parts of the apparatus shown in Fig. 3 are the same as in Figs. 1 and 2 but slightly changed in form or in their relative positions. Thus the crusher of Fig. 1 is shown in Fig. 3 as supported upon the ground. The material treated therein is raised by a suitable elcvator 36 to a chute 37 from which it is discharged into a hopper 38 for delivery to an impact mill similar to that shown in Fig. 2.

The sequence of operations involved in the treatment of the material is the same as that described with reference to Figs. 1 and 2. That is, the material treated in the impact mill is given a whirling motion by the action of the rotating hammers, and falls by gravity into the separator where it commingles with the material discharged from the pulverizer. The usable fines from both masses are conveyed away through pipe 25 while the heavier particles which are thrown outward toward the wall of the separator are collected in hopper 11 to be again passed through the pulverizer.

Again referring to Fig. 2, while I have shown and described an impact pulverizer in place of the crusher illustrated in Fig. 1, it is of course obvious that other types of pulverizing mills may be equally suitable for the purpose. It is understood therefore, in this application of my invention, I do not limit it to the use of an impact mill.

What I claim as new is:-

l. A pulverizer having a chamber with fixed members therein so disposed as to provide tortuous passages for the material to be pulverized, means for passing through said chamber of gaseous medium carrying said material in suspension, and means for cleaning the passages between said members of material lodged therein, said last mentioned means including means for rotating the pulverizer chamber to relatively displace the fixed members with respect to one another whereby clogging is prevented.

2. The combination of a housing, a pulverizing mill in the upper part thereof and opening directly thereinto, a second pulverizer, a pipe leading from the latter to said housing and entering the latter tangentially to its wall below said first named mill, whereby the products of both mills will be commingled and given a whirling motion, and a delivery pipe leading from said housing, the intake of said pipe being substantially at the center of the vortex.

3. A pulverizing apparatus comprising a pulverizing mill, a housing below said mill into which said mill discharges, the material falling by gravity directly into the aforesaid housing, a second pulverizer without said housing but into which said housing in turn discharges, means for discharging the material from said second pulverizer directly back into said housing, and means for withdrawing the fines from said housing.

4. A pulverizing apparatus comprising a pulverizing mill, a housing below said mill into which said mill discharges its pulverized material which falls directly downwardly by gravity through said housing, a second pulverizer without said housing but into which said housing in turn discharges, means for discharging the material from said second pulverizer directly back into said housing, and means for withdrawing the fines from said housing.

5. The invention set forth in claim 4 in which an outlet from said second pulverizer is provided discharging into the upper part of the housing.

6. A pulverizing apparatus comprising a housing, a pulverizing mill above said housing discharging material directly and by gravity into the upper part of said housing and freely downwardly therethrough, all of the material initially supplied to said housing passing through the aforesaid pulverizing mill, means for removing fines delivered by the aforesaid mill-from said housing, a second pulverizer without said housing but into which said housing discharges its coarse material, means for delivering material back into said housing from said second pulverizer, the aforesaid means which remove the fines delivered by the first pulverizer mill from the housing also serving to remove the fines delivered by the second pulverizer to said housing.

ERNEST H. PEABODY.

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