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Publication numberUS3341011 A
Publication typeGrant
Publication dateSep 12, 1967
Filing dateMar 4, 1965
Priority dateMar 4, 1965
Publication numberUS 3341011 A, US 3341011A, US-A-3341011, US3341011 A, US3341011A
InventorsPrescott Donald R
Original AssigneeSegredyne Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Separation of solids in a gaseous current
US 3341011 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

p 1 96 o. R. PRESCOTT SEPARATION OF SOLIDS IN A GASEOUS CURRENT 2 Sheets-Sheet 1 Filed March 4, 1965 p 1 1967 D. R. PRESCOTT SEPARATION OF SOLIDS iN A GASEOUS CURRENT Filed March 4, 1965 2 Sheets-Sheet f3 United States Patent ()fiice 3,341,011 Patented Sept. 12, 1967 3,341,011 SEPARATION OF SOLIDS IN A GASEOUS CURRENT Donald R. Prescott, West Newton, Mass'., assignor to Segredyne Corporation, Cambridge, Mass., a corporation of Massachusetts Filed Mar. 4, 1965, Ser. No. 437,202 11 Claims. (Cl. 209-144) ABSTRACT OF THE DISCLOSURE Elongated particles having one long dimension are separated from other particles all dimensions of which are less than the long dimension, by moving all the particles in contact with a gaseous medium, providing a differential velocity between the particles and the medium sufficient to align the elongated particles with their longest dimension generally perpendicular to the direction of their flow, thereafter guiding the particles onto an inner surface circular in cross-section, and moving the particles circularly and downwardly over holes large enough to accept all dimensions of the elongated particles except the long one.

This invention relates to separating mixtures of solid particles. More particularly, it makes possible efiicient separation of elongated particles of dimensional integrity and with first dimensions larger than their other two from other particles in which no dimension is as large as said first dimensions.

It is the primary object of the invention to make possible the separation as just mentioned. A further object is to do so with minimized loss of the elongated particles, even though the particles from which they are separated are thrown out through holes much greater in diameter than any dimension but the longest of the large elongated particles, not permitted to go through the holes. Further objects are to accomplish this without blocking holes with generally wedge-shaped or other particles, or with fibrous or gummy or other materials; to provide improved cleaning of the large elongated particles; and to make possible saving of desirable materials that would otherwise be Wasted.

Generally speaking, the invention features moving a mixture of the above-mentioned elongated particles and the abovementioned other particles in a stream and in contact with a gaseous medium, giving to all the particles and to the gaseous medium different velocities, directing the stream onto a surface closedly circular in cross-section, and moving the particles therefrom over a perforate member with a surface circular in cross section and interrupted by openings large enough to accept all dimensions of all said particles except the longest dimension of the said elongated particles. In preferred embodiments, the particles are pneumatically conveyed, with low weight ratios of gaseous medium to particles at an initial velocity over 5000 feet per minute; the differential velocity is thereafter provided by increasing the cross-sectional area of a conduit; the particles are guided into a thinned stream and tangentially of the closedly circular surface by changing the direction of the conduit to provide centrifugal forces biasing the particles so; and the openings are several times larger than the particles to be moved therethrough. In the most preferred embodiment, wood chips (including pegs and matchsticks) are separated from bark, sawdust, grit, and stone in preparation for digestion in pulpmaking for manufacture of paper.

Other objects, features, and advantages will appear from the following description of a preferred embodiment of the invention, taken with the attached drawings thereof, in which:

FIG. ,1 is a broken away view of the inner surface of the perforate member over which the particles are moving in a downwardly circling direction, near the inlet end thereof;

FIG. 2 is a diagrammatic view showing chips, matchsticks, and pegs retained inside the perforate member;

FIG. 3 is a view of four categories of particles thrown out through the holes in the perforate members, grit, stone, sawdust, and bark particles;

FIG. 4 is a plan view of a separator with which the invention may be practiced;

FIG. 5 is a side elevation of said separator;

FIG. 6 is an auxiliary view at 66 of FIG. 5; and

FIG. 7 is an enlarged, partial, vertical sectional view showing the perforate member and adjacent parts.

Referring now more particularly to the drawings, there is shown in FIG. 5 a separator indicated generally at 10 with a head 12 having a smooth cylindrical inner surface 14 and an inlet portion 16 and gas outlet 17. Mounted beneath surface 14 coaxially therewith is generally frustoconical perforate member 18, with an unperforated smooth upper portion 20 for initially accepting downwardly dropping particles without undue wear, and a perforate lower portion 22, which terminates in exhaust portion 24. Particles passing through the holes in perforate member 18 are caught by frustoconical member 26 and emerge through exhaust 28.

Conduit 30 is connected to inlet portion 16 through transition piece 32, which is round like the conduit at its conduit end 34, and rectangular like inlet portion 16 (with three times the round end cross-sectional area) at its inlet portion end. Inlet portion 16 (and other portions subject to heavy particle wear) may if desired be provided with liners.

In operation, a mixture of chips 40, pegs 42, matchsticks 44 (the latter two being industry expressions for bits of fibrous wood of characteristic shape), grit 46, stone 48, sawdust 50, and bark 52 is pneumatically carried by air (0.2 pound of air per pound of particles in the preferred embodiment; the range is 0.15 to 1.0) through conduit 30 at 10,000 feet per minute. The crosssectional area of the conduit is about 78 square inches and that of the inner portion 16 about 200 square inches, so the air is slowed to a velocity of about 3,400 feet per minute in the transition piece 32. The particles, however, through inertia keep most of their 10,000 feet speed, whereby a considerable speed differential between air and particles is produced in the transition piece. This speed differential makes elongated particles swing so that their longest dimension becomes generally perpendicular to the direction of flow. In inlet portion 16, then, the curve brings the particles into a thinned layer away from the center of curvature. Actually, in this embodiment, conduit 30 has an inner diameter of about 12 inches, while inner portion 16 has a cross-sectional inner area of 12 inches by 20 inches; the layer formed is however only about an inch thick, with the largest dimension of many chips 40 about inch. These combined alignment and thinning steps permit introduction of the particles over cylindrical surface 14 generally tangentially thereto, and with a particle surface of each elongated particle corresponding to the longest dimension thereof generally against surface 14 upon impact on surface 14. This relationship is then maintained and reinforced as the particles spin around and around as they move downwardly over surfaces 14, 20, and 22 (as they leave the latter the particles still have a speed of about 1000 feet per minute). Although the holes in perforate member 20 are inch in diameter, the material which passes therethrough looks like that passed by a conventional inch screen. Thus small material is ejected through holes three times as large in diameter, with consequent increase in speed, elimination of blocking, and increase in efiiciency; alignment of the elongated pegs and matchsticks makes them bridge holes they would easily be lost through otherwise, saving them and avoiding a great loss of valuable fibrous material. Furthermore, alignment prevents wedge-shaped elongated particles from starting into holes and then blocking them. And the high turbulence created by the particle speeds involved prevents any build-up at the holes of fibrous, gummy, or other material.

Particles with more than one dimension greater than the hole size, such as many chips 40, are of course retained with the elongated particles, on conventional principles.

Other embodiments of the invention will be apparent to those skilled in the art and are within the following claims.

I claim:

1. The method of separating elongated particles with a longest first dimension from other particles all dimensions of which are less than said first dimension which comprises moving all said particles in contact with a gaseous medium, providing a differential velocity between said particles and said medium sufficient to align said elongated particles with their longest dimension generally perpendicular to the direction of their flow, thereafter guiding said particles onto an inner surface circular in cross-section, and moving said particles circularly and downwardly over holes large enough to accept all dimensions of said elongated particles except said first dimension.

2. The method of separating elongated particles with a longest first dimension from other particles all dimensions of which are less than said first dimension which comprises moving all said particles in contact with a gaseous medium, providing a differential velocity between said particles and said medium sufficient to align said elongated particles with their longest dimension generally perpendicular to the direction of their flow, thereafter bringing said particles together in a thinner layer, guiding said thinner layer tangentially onto an inner surface circular in cross-section, and moving said particles circularly and downwardly over holes large enough to accept all dimensions of said elongated particles except said first dimension.

3. The method of claim 2 in which said elongated particles are wood pegs and matchsticks and said other particles include bark and sawdust.

4-. The method of claim 3 in which said holes are round and of diameter a plurality of times greater than the largest dimension of the bulk of said other particles.

5. The method of claim 2 in which said particles and said gaseous medium initially move together and at a speed in excess of 5000 feet per minute.

6. The method of claim 5 in which said speed is 10,000 feet per minute.

7. The method of claim 5 in which the velocity of said medium is reduced at least just before said particles are brought together in said thinner layer.

8. The method of claim 2 in which said thinner layer is produced by centrifugal action on said particles.

9. The method of claim 2 in which said layer is of thickness less than twice the largest dimension of particles ordinarily present therein.

10. The method of claim 5 in which said gaseous medium is air and the weight ratio thereof to said particles is 0.15 to 1.0.

11. The method of claim 10 in which said ratio is 0.2.

References Cited UNITED STATES PATENTS 603,285 5/1898 Porbeck 209-250 X 938,702 11/1909 Porbeck 209250 X 1,224,898 5/1917 Brennen 209-144 2,991,883 7/1961 Hendrickson 209-144 OTHER REFERENCES Taggart: Handbook of Mineral Dressing, 1945 (9-10 through 9l3 FRANK W. LUTTER, Primary Examiner.

HARRY B. THORNTON, Examiner.

R. HALPER, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US603285 *Sep 27, 1897May 3, 1898 Dust-collector
US938702 *Oct 10, 1908Nov 2, 1909Otto PorbeckDust collector and separator.
US1224898 *Apr 29, 1916May 8, 1917Frederic W BrennenShavings and sawdust separator.
US2991883 *May 10, 1957Jul 11, 1961Lester C HendricksonGrain handling machine
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3416660 *Sep 2, 1966Dec 17, 1968Karlstad Mekaniska AbScreens, particularly for wood chips
US4269701 *Aug 27, 1979May 26, 1981Temafa Textilemaschinenfabrik GmbhCyclone separator for the removal of heavy particles and dust particles from fibre material
US4477339 *Aug 27, 1982Oct 16, 1984Whaley John PCyclone classifier
US5509539 *Dec 21, 1993Apr 23, 1996Nec Electronics IncorporatedMethod for preparing injection molding compound pellets to remove molding compound dust and broken pellets
Classifications
U.S. Classification209/2, 209/250, 209/23, 209/281, 209/305, 209/263
International ClassificationB07B7/086, B07B7/00
Cooperative ClassificationB07B7/086
European ClassificationB07B7/086