US2696911A - Separation of airborne particles - Google Patents

Description

E. R. UMNEY SEPARATION OF AIRBORNE PARTICLES Dec. 14, 1954 Filed Jan. '7, 1952 I IN YEA/T0,? .LAum fE E. R. UMNE! United States Patent SEPARATION OF AIRBORNE PARTICLES Laurie E. R. Umney, Guildford, England, assignor to Vokes Limited, Guildford, England Application January 7, 1952, Serial No. 265,306 Claims priority, application Great Britain January 9, 1951 4 Claims. (Cl. 209-142) According to the invention an airborne stream of 9 particles of varying size is caused to follow an arcuate or curved path through a conduit under the influence of pressure past an oppositely facing circumferentially disposed lip in the outer wall of the conduit and a relatively small flow of air is induced through a slot past the lip into a recessed pocket in the conduit in the reverse direction to the main flow therein whereby the particles of smaller order of size and momentum are decelerated and are deflected back into the main stream with the small flow while the larger particles are carried forward past the lip by their greater momentum and fall into a collector disposed beneath the lip.

In a preferred form of apparatus the main flow of air is sucked through the conduit by an extraction fan and the reverse flow of air through the slot is induced through an air inlet in the receptacle by thesame fan.

In operation the larger particles in the main air flow pass through the region of reverse air flow without being stopped due to their higher momentum and so pass through the slot into the receptacle provided. However the smaller particles which have a lower momentum are arrested by and become entrained in the reverse air flow and are thus prevented from entering the receptacle.

The above and other parts of the invention are embodied in a preferred form of apparatus which will now be described in some detail by way of example with reference to the accompanying drawings in which:

Fig. 1 is a sectional view of a separator,

2 is a half sectional view on the line IIII of The curved conduit 1 is square in cross-section and a suitable dimension is 2 /2 x 2 /2. The inner circumferential wall 1a at the inlet end has a curvature of 3 /2" radius and the outer wall 1b a curvature of 6" radius over 60, and then over 75 the walls have curvatures of 9%" and 12 /2 radius respectively, but the outer wall is formed with a recessed pocket 2, deep and extending over 26 of the circumferencefrom a point 90 after the inception of the larger radius of curvature.

Where the pocket 2 ends a slot 3 is defined with the normal continuation 1c of the outer wall which'thus constitutes a circumferentially arranged lip facing the inlet end of the conduit.

Below and behind the lip is arranged an outlet channel 4-5" x 2 /2. The outer channel has a rubber faced flange 5 for the attachment of a receptacle 6 by means of swinging arms 7 carrying screw bolts 8.

A partition 9 in the receptacle has a narrow horizontal slot 10 for the ingress of air through holes 11 in the outer wall 12 on the side adjacent the conduit outlet.

An extractor fan (not shown) is fitted at the outlet end of the conduit, either directly or at the outlet from an associated dust recovery plant collecting the finer I particles.

The size and location of the narrow slot in the receptacles are important factors effecting the effectiveness of the particle separation which are best discovered experimentally for individual installations.

In the apparatus described above the slot 10 is A" deep by 5 /8 long, and its centre is located some 7 /2" below and behind the centre of the slot in the main conduit. The broken line joining the centres of the slots is at an angle of about 35 with the horizontal.

The form of apparatus above described is designed for the extraction of leaf flakes from mixed tobacco particles in an air stream of C. M. F. in a direction of flow that is from left to right in conduit 1 as regards the disclosure of the invention in Fig. 1.

It will be understood that the particular dimensions and arrangements of the parts can be widely varied to suit difierent applications and conditions and that such variations are included within the invention in its broader aspects.

For example the suction fan can be replaced by a pressure fan at the inlet end of the conduit and the flow through the gap can be supplied by this or another pressure fan.

I claim:

1. Apparatus for the separation of particles of a larger order of size from an airborne stream of particles of varying size comprising a curved conduit through which may be induced a flow of particle laden air, a recessed pocket in the outer circumferetial wall of the conduit, a circumferentially disposed lip defining a slot with the outer wall of the pocket, a receptacle for collected particles arranged below and in communication with the slot, a fan for inducing a relatively small flow of air through the slot and an air inlet in said receptacle for said fan.

2. Apparatus according to claim 1 in which the re ceptacle is provided with an air inlet in a wall on the side adjacent the conduit outlet.

3. Apparatus according to claim 1 in which the receptacle is provided with a double wall on the side adjacent the conduit outlet, an air inlet slot in the inner wall and a series of air inlet apertures in the outer wall.

4. Apparatus for the separation of larger particles from an airstream including smaller particles comprising a curved conduit of rectangular cross-section the radius of curvature of which is smaller at its inlet end than at its outlet end, a recessed pocket in the outer wall of the conduit, a lip constituted by the outer wall of the conduit beyond the recess and defining a slot with the outer wall of the recess, a receptacle arranged below the slot, an air inlet in a wall of the receptacle on the side adjacent the conduit outlet, and means to induce an air flow through the conduit and through the slot.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 821,819 Neumann May 29, 1906 1,023,750 Morscher Apr. 16, 1912 1,264,023 Davis Apr. 23, 1918 2,044,915 Mosely June 23, 1936 2,283,483 Arnold May 19, 1942 FOREIGN PATENTS Number Country Date 120,673 Sweden Nov. 20, 1947 483,307 Germany Sept. 28, 1929

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