US2094438A

US2094438A - Sifter system

Info

Publication number: US2094438A
Application number: US51045A
Authority: US
Inventors: Myron J Watson
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-11-22
Filing date: 1935-11-22
Publication date: 1937-09-28
Anticipated expiration: 1954-09-28

Description

Sept. 28, 1937. I M. J. WATSON 2,094,433

SIF'IER SYSTEM Filed Nov. 22, 1935' 2 Sheets-Sheet 1 Fig.1.

Inventor M. J. WATSON Sept. 28, 1937.

SIFTER SYSTEM Filed Nov. 22, 1935 2 Sheets-Sheet 2 111 we ntor a /Mm/ /%/)7. 3

Patented Sept. 28, 1937 UNITED STATES PATENT OFFICE SIFTER SYSTEM Myron J. Watson, Chicago, Ill. Application November 22, 1935, Serial No. 51,045

4 Claims.

This invention relates to certain new and useful improvements in siftersystems, the peculiarities of which will be hereinafter fully described and claimed.

My. present invention relates to that class of sifter systems in which finely pulverized material, such as grain, rock, mineral or other material, is finely pulverized in a suitable machine and then delivered to my system under compressed f as air currents in which the material is held in suspension, and by my construction of sifter system is prevented fromclogging or undesired deposit within the. system, so that said material: is continuallyinmotion and divided by the sifter device intothe'desired grades of fineness, some of which grades aredrawn off at definite points of the system, while the balance containing the finest particles of .materialis finally separated from the blast air and drawn off in its finished condition as a finally finely pulverized product.

Witli the:above objects in view, my system comprises a casing of-an inverted conical shape inwhich is mounted. a conical screen having openings of the desired fineness, and a corresponding conical rotary frame carrying brushes which engage the inner :side of'the screen and by their continual rotary contact, prevent clogging of theopenings in the screen, and maintain the particles of the material constantly'in motion in thevehicular blast. air currents passing through thepreliminary sifter to the final cyclone collector in which latter the compressed air is separated from the finest particles, while said particles are drawn oil as finished product.

. Another object is to provide such construction of the sifter that the frame and'brushes, and the screen itself, are easily accessible so that they can be readily removed for change or replacement as V desired.

Another object is the provision of a safety device by which'the pressure of a possible explosion within said chamber maybe relieved and avoid,

rupture of the system. H 7 V Another object is to rotate said brushes by the force of the entering blast air.

f Another object is tocontrol the speed of rotatio'nof the said brushes'by means operated by the entering blast airfand to increase or lessen the rotative speed as may be desired.

.Another object is to provide means for keeping the pulverized material in suspension by agitating: and deflecting the entering blastair bearing 7 said material, to avoid its clogging the screen and its tendency to lodge within the Sifter.

sectional plane 2--'2, Fig. 1, showing deflecting 7 blades and a supporting frame therefor;

Fig. 3, a vertical section on the line 3-3, Fig.

2, showing a brush mechanism operated by fan blades in :the path of the entering blast air;

Fig. i, a plan view of a cyclone collector on a sectional plane 44, Fig. 1; and

Fig. 5, a sectional elevation of said cyclone collector on the line 5-5 of Fig. 4.

Referring to the drawings, the numeral I designates a pulverizer of suitable type for pulverizing grain, rock, mineral or other material.. Such pulverized material. is delivered by a pipe 2 to a blast fan 3 which isconnected by a pipe 4 to an upright casing 5"having a cylindrical top 6 and a conical bottom portion 1. The cylindrical portion. has a top 8 which is detachably, mounted thereon and held by set screws or otherwise but may be readily removed to give access to the interior of the casing and remove the operating devices now to be described. r

In the conical part of this casing is mounted a conical screen 9 having a. packingring ill at the top so that the blast air. with its pulverized material will be delivered tothe inside of the screen. The fines that pass through the screen are delivered by a downwardly inclined pipe H to a suitable collector such as a cyclone collector W to separate the air from the fines'which latter are discharged from the bottom of the cyclone into .a. bag or otherreceptacle; while the air, freed of the fines, escapes through the center outletl3. T

The coarse particles of the pulverized material which 'donot pass through the screen 9, are delivered as tailings through a pipe M connected .to the bottom of said screen and passing out through said pipe H and ending in asacking spout or other valve device i5 which prevents the escape of the tailings until opened for their discharge. I In the central axis of said screen is mounte a rod or shaft I6 in a bearing at the top and bottom. This shaft is freely rotatable and has an adjusting screw I! at the lower bearing or is sired. On this shaft is mounted a conical frame connected at the top by radiating arms to the shaft and carrying brushes IS on the inclined portions of said frame, which brushes are substantially in contact with the inner face of said screen 9. The brushes may be adjusted by said adjusting screw to vary their contact with the screen, or by any other suitable means. As these brushes rotate, by means presently to be described, they keep the openings in the screen clear for the passage of fines which pass through the pipe H to said cyclone or other collector.

In the cylindrical chamber above the conical portion, is mounted a series of radiating frames 19 carried by said shaft I6 as shown in Figs. 2 and 3. In said frames are pivotally mounted defiecting blades 20' which are varied in their inclination by rotation on their horizontal axes by suitable adjusting means, such as a vertical handle 2i having a pinion and bevelled gear connection with the axis of each blade. Access is had to adjust the inclination of these blades through a capped opening 22.

Rotation is effected by the impact of the material carrying blast air entering the casing and impinging upon said blades as a fan, which causes rotation of the shaft 16 and the conical frame and brushes also carried by said shaft.

While these blades deflect the blast air downward like a fan, they are motivated by the impact of the entering air currents, similar to turbine blades actuated by water impact. The brush-carrying shaft being freely rotatable and having such turbine fan mounted thereon, is therefore driven by the said blades. Also the speed of rotation is varied by adjustment of the inclination of these fan blades, which is a function not possessed by fixed turbine blades.

When said blades are vertically disposed, the velocity of the fan and of the brushes will be{ greater than when said blades are inclined more or less to the horizontal. When the blades. are inclined, the pulverized material in the entering blast air is deflected downward into the conical screen where such material is agitated by the brush frame as it seeks outlet through the screen. The radiating arms IQ of the fan frame likewise agitate the material in suspension as the said frame is rotated under the impulse of the entering air as just described.

Thus any tendency of the pulverized material to lodge or clog the screen or other part of the sifter .cone, is practically avoided, and at the same time the said particles are so agitated and kept in suspension, that the fines quickly and readily find exit through the screen openings into the casing and are forced onward into said collector by the pressure of the blast air.

The screen is provided with hooks 23, and the top 8 of said casing when removed therefrom, allows of drawing up the screen by passing a lifting rope under said hooks, when the screen. is to be changed to another of different fineness as may be required for the material being sifted.

Likewise the shaft I6 carrying the fan and the conical frame with the brushes, may also be drawn up from the lower bearing in which the shaft is mounted.

The casing I2 is provided with glazed openings 24 at different heights, by which theoperation of the brushes may be viewed from outside and adjustment made accordingly. The usual clean out opening 25 near the bottom of .:the casing gives access, for adjustment of the shaft carryotherwise adapted to be raised or lowered as deing the brushes when desired to make closer or lesser contact of the samewith the conical screen.

Thus it will be seen that the rotation of the brushes is effected by means entirely within the casing, and not operated by outside connections; also that the speed of rotation can be controlled by adjusting the inclination of the fan blades to the entering blast air; also that the fan frame and the brush frame cooperate in agitating the air and keeping the pulverized material in suspension so that the fines will be readily passed through the screen and onward to the collector, while the tailings are discharged through the valvular device 15 before mentioned.

As the fines enter the cyclone collector tangentially under the continued impulse of the blast air, the centrifugal motion in the upper part of the cyclone increases as the material descends the conical lower portion, and causes a vortex in the center and an upward motion of the air to the discharge opening it connected to the tubular 25 depending from the top of the cyclone.

The velocity of the particle-laden air entering the large upper portion of the cyclone collector is substantially unchanged when the air-carried particles change from their straight tangential entering direction to a circular movement by which a centrifugal action is exerted on the particles causing them to hug the inner wall of the collector chamber. As the diameter of this downwardly tapering cone decreases, the velocity remains substantially uniform, but the rotary motion increases, and likewise the centrifugal tendency while the particles spiral downward, causing practical separation of the pulverized material from its vehicular air and condensation of the latter which seeks exit through the small bottom outlet and upward through the tubular 26 to the said discharged opening [3.

The lightest particles are not so readily separated by centrifugal action from the whirling air currents as the larger particles, and are thus liable to be carried out the upper discharge opening with the purified air unless the diameter of the tubular bears a certain definite relation to the condensed air pressure which would avoid such loss. In the usual more or less approximation to this perfect proportion, many of these lightest particles would escape through the air discharge opening 26 if it were not for a collecting device that I have provided by which most of these lightest particles are taken. out of the whirling air currents at or near the point of greatest compression near the bottom outlet of the cone, and are returned by a communicating pipe to a point in the upper part of the cyclonecollector where they will again mingle with the particle-laden air entering the tangential inlet. The air pressure is also distributed by this return pipe,'such as through a vertical pipe 21. This pipe is mounted in the axis of the cyclone and its lower end hangs adjacent to the lower discharge opening. The upper portion of said pipe passes outside the tubular and is curved in the direction of the material laden air entering the cyclone as shownin Fig. 4. Thus the air passing upward through said pipe and outward through the curved end adjacent to the cyclone inlet, merges the air currents from said pipe with the entering blast air under the force of the air pressurein the lower portion of the cyclone collector. 7

Referring again to the sifter casing, the opening 22 has its cap 22 detachably mounted so as to serve as a safety. cap and relieve the pressure within the casing, in the event of an explosion of the dust therein.

I claim:

1. A sifter system comprising an upright casing having a conical bottom and a top forming an upper chamber with a tangential inlet subject to mixed feed of blast air and pulverized material in suspension, a vertical freely rotatable shaft mounted in the axis of said casing, radiating frames supported by said shaft, adjustable fan blades pivotally mounted in said frames in the path of the entering mixed feed blast acting to drive said shaft and inclined so as to deflect said blast downwardly into said conical bottom, means to Vary adjustably the inclination of said blades, a conical frame carrying brushes operably connected to said fan blade frames, a conical screen mounted in said conical bottom subjected to rotary downward currents of material in suspension, and outlet pipes forthe fines and tails from said screen, substantially as described.

2. A sifter system as in the last claim, the means for adjusting the fanblades consisting of a vertical handle having a pinion and bevel gear connection with each blade. 7 I

3. A sifter system comprising an upright casing having a lower portion, and a top portion forming a cylindrical chamber with a tangential inlet for material-laden air currents, a screen in said lower portion, a freely rotatable shaft in the axis of said casing, brushes adjacent said screen and carried by said shaft, and driving means for said shaft characterized by a set of inclined radiating blades mounted in said chamber on said shaft in the path of the entering air currents and driven thereby, and acting to deflect said currents downwardly into said lower portion and against said screen, and outlet pipes for coarse and finer particles.

4. A sifter system comprising an upright casing having a cylindrical top portion with a tangential inlet subject to blast air currents containing pulverized material, a lower portion of said casing containing a screen, a freely rotatable shaft therein carrying screen-cleaning brushes, and provided with outlets for coarse and finer particles, and said top portion containing combined shaft-driving and air-deflecting means, and agitating means for the material in suspension in said air currents,both said means being actuated by the blast air currents entering by said tangential inlet.

' MYRON J. WATSON.