US2883059A - Settling device - Google Patents

Description

April 1959 1. E. PUDDINGTON ETAL 2,883,059

' SETTLING DEVICE Filed May 10, 195.7

Atomzy United States Patent SETILING DEVICE Ira E. Puddington and Allan E. Mcllhinney, Ottawa, ntario, and Alfred Lorenzo, Edmonton, Alberta, Canada, assignors to National Research Council, Ottawa, Canada, a body corporate of Canada Application May 10, 1957, Serial No. 658,354

5 Claims. (Cl. 210-519) that the feed of the material under treatment be such as to cause a minimum of disturbance in; the settling chamber due to the formation of currents While the problem of providing a satisfactory feeding system has been previously recognized, no fully effective solution has heretofore been proposed.

It is an object of this invention to provide a settling device having a simple convenient feeding arrangement adapted to ensure the highest possible operating efficiency of the device.

To this end, the invention comprises, in a settling de: vice having at least one angularly arranged container having top, bottom and side walls, means for feeding fluid suspension to said container comprising a baffle plate disposed between and spaced from said top and bottom walls and extending longitudinally through a minor portion of said container, a feeding conduit extending through at least one of said side walls and disposed between said top wall and plate, said conduit having a plurality of feed Patented Apr. 21, 1959 end throughout a minor portion of the longitudinal extent of the container. This minor portion may be-of the order of A the length of the container. For example, a plate 10 to 12 inches wide in a container 8 feet long is satisfactory.

The plate 7 has a right angular flange 8 extending from its lower edge towards but preferably spaced from top Wall 4. Mounted on the plate and extending substantially right angularly therefrom and from the flange 8 are a plurality of uniformly spaced baffles 9. It will be apparent that baffles 9 are in generally parallel relation to the side walls 2 of the container. Furthermore, the baflles 9 preferably extend upwardly into substantial engagement with top wall 4.

A feed tube or conduit 10 extends through the side walls 2 and transversely of the container. The conduit is located above the plate.7 and closely adjacent the flange 8. Thus, the conduit also extends through each baflle 9 adjacent its lower end. The conduit has a plurality of aligned openings 11 therein, each opening being preferably in the form of a slot the longitudinal extent of which is in the axial directionof the conduit. While the size of the slots may vary, a slot inch wide and 1 long, with a spacing of 2 inches along the length of the conduit, has been found satisfactory.

As shown each baifle 9 may be located substantially midway between each pair of adjacent slots. It will be' understood that more than one opening 11 may be provided between each pair of baflles. Each baflle extends several inches upwardly from the feed conduit 10. Thus, in using a feed conduit of /8 inch internal diameter, a bathe of 5 inches long is satisfactory.

The feed tube 10 is preferably removab-ly mounted in the container so that it may be readily removed for cleaning purposes as desired. To this end, it is proposed that the feed tube be retained in operative position by reason of its frictional engagement with side walls 2 and baflles openings within said container, and a plurality of substantially parallel baflles extending substantially perpendicularly from said plate and conduit, at least one of said openings being located between each pair of bafiles.

The invention will be described with reference to the accompanying drawing, in which Figure 1 is a plan view of a settling device in accordance with the invention.

Figure 2 is a side elevation partly in section, and

Figure 3 is a partial end elevation.

In the drawing, 1 is a container having side walls 2, bottom wall 3 and top wall 4. The side walls 2 are relatively narrow to provide a broad shallow container. The proportional dimensions of the container may vary greatly but, as shown, they may be of the order of 4 feet wide, 8 feet long, with about 2 inches spacing between walls 3 and 4. In operation, the container is adapted to be disposed in an inclined or angular position as shown in Figure 2. The angle of inclination should be approximately 40 to 60 from the horizontal. The upper end of the container may be open, as shown, and the lower end communicates with a downwardly extending collecting vessel 6, which converges towards a discharge pipe 6a leading therefrom.

Feeding means in accordance with the invention comprises a bafiie plate 7 which, as shown, is arranged within the container in substantially parallel relation to top and bottom walls 4 and 3 and in spaced relation thereto. Thus, the plate may be substantially midway between walls 3 and 4, but under some circumstances it may be closer to the top wall or to the bottom wall. The plate 7 preferably extends from one side wall 2 to the other 9. Such a mounting also permits rotative adjustment of the feed tube relative to the container. Thus, while the slots 11 are preferably and normally disposed somewhat closer to the top wall 4 than to the bottom wall 3, whereby flow therefrom is directed upwardly and substantially parallel to walls 4 and 3, it may be desirable in some instances to vary such direction of flow.

The feed tube 10 and its associated elements is preferably located as shown, namely adjacent the bottom of the container. However, it may be placed at various locations in the container depending upon the type of material under treatment and the velocity of feed. Ordinarily, it should be located at the level in the container in such a way that the natural convection currents in the material under treatment are disturbed as little as possible.

A collecting trough 12 having an outlet 13 extends transversely through the container adjacent the upper end thereof.

In operation, the fluid suspension under treatment is fed into feed tube 10. Preferably, feed is introduced in equal degree into both ends of the tube in order to provide substantially uniform velocity of flow from the slots 11 into the container. The bafiles 9 prevent the formation of transverse currents in the flow of liquid in the container and tend to produce instead longitudinal currents. The restricted cross-section of flow effected by the plate 7 between the bafiles 9 and beyond the latter tends to promote uniform distribution of feed across the width of the container. The use of slots permits a relatively large port area in a feeding tube small enough in diameter to give a liquid velocity suflicient to prevent the solids from settling out in the tube itself. Moreover, slots are less likely to become plugged with solids than are circular openings. The formation of longitudinal currents as near a the point of feeding as possible is desirable to minimize the effects of turbulence throughout the settling chamber.

The plate 7 is so arranged that solids in the suspension undertreatment, which are carried partway upthe container by the longitudinal currents, drop, towards the bottom wall 3 as the current velocity decreases, and are carried in the downwardly moving. convection current which is caused by the density gradient in the suspension normal to the walls 3 and 4 owing. to vertical settling of the solid particles, such current passing beneath the plate 7. The solids continue down into the vessel. 6 and are finally discharged therefrom. Clear liquid from which, solids have separated is collected in the trough 12 at the top of the container and is dischargedthrough outlet 13. V

Restricting the space between plate and top wall 4 by means of theflange 8 below thefeed tube. 10 prevents the formation of circular currents around the feed' tube which would interfere with the settling movement of the solids.

The device described permits suflicient jet velocity of feed to avoid plugging, while introducing such. feed in such a way that there is a minimum of disturbance due to the formation of currents in the suspension under treatment.

It will be understood that, while the device has. beendescribed with respect to a single cell or container 1, the device may comprise a plurality of such cells.

We claim:

1. In a. settling device having a container disposed. at an angle to the horizontal and-having generally rectangular top, bottom and side walls, means for feeding fluid suspension to said container comprising a feed conduit extending through at least one of said side walls and. disposed between said top and bottom walls, said conduit having a plurality of feed. openings. within said container, a bafiie plate extending transversely within the container and located between said conduit and said bottomwall and spaced from said bottom wall, said baffie plate extending longitudinally through a minor portion of said container, and a plurality of substantially parallel baflies extending substantially perpendicularly from said baffle plate and conduit, at least one of said baffies being disposed between each pair of adjacent openings.

:2. A settling device as defined in claim 1, said baflie 4 plate being in substantially parallel relation to said top and bottom walls. v

3. A settling device as defined in claim 1, said baflle plate having a flange extending from its lower edge upwardly towards said top wall, said conduit being located in adjoining relation to said flange, and said baffies each having an end edge in substantial engagement with said flange.

4. A settling device as defined in claim 1, said feed conduit being removably mounted in said container and extending-through both said side walls whereby feed may be effected from both ends of said conduit.

5. In a settling device having a container disposed at an angle to'the horizontal and having top, bottom and side walls, means for feeding fluid suspension to said container comprising a feed conduit extending through said side walls and having a plurality of feed slots within said container, the longitudinal extent of said slots being; disposed in the axial direction of said conduit, said conduit being located adjacent the lower end of said container and having said slots directed upwardly, a baffle plate extending transversely within said container from side wall to side wall and located in spaced relation to said top and bottom Wall's, said conduit being disposed between said batfie plate and top wall, said baffle plate extending longitudinally through a minor portion of said container and having a flange extending from its lower edge towards, said top wall, and a plurality of substantially parallel, haffles extending substantially perpendicularly from. said. baffle plate and conduit and towards said top wall, each said baffle being disposed between an adjacent pair of said slots and extending longitudinally from said flange, and terminating below the upper edge of said bathe plate, a collecting vessel communicating with the lower end of said container, and a collecting trough in said container adjacent the upper end thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,940,794 Fisher Dec. 26, 1933 2,728,457 Clarke Dec. 27, 195.5.

FOREIGN PATENTS 1,015,977 France Aug. 13, 1952 746,980 Great Britain .Mar. 21,, 1956

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