US2603355A - Decantation apparatus - Google Patents

Description

y 15, 1952 H. E. LEWIS 2,603,355

DECANTATION APPARATUS Filed Sept. 2, 1947 attor negj Snocntor:

Patented July 15, 1952 per cent to Susan Lewis Rasmussen, twenty per cent to Emille G. Jensen, and ten per cent to Philip H. Mallinckrodt and Philip rodt, all of Salt Lake City, Utah A. Mallinck- Application September 2, 1947, Serial No. 771,682

Claims. (Cl. 210-51) This invention relates to decantation apparatus, and more particularly to such apparatus as applied to solutions having .delayed settling properties.

The principal object of the invention is to provide a device that makes possible a clean separation of extremely fine solids from solutions in which the fine particles are held just short of balanced suspension. Other important objects include the attainment of Simplicity in construction and operation;

Assurance of quiescence of the settled fine particles during the decanting procedure;

Convenience and reliability in operation;

Expeditious handling of both settled material and the clarified solution.

Other objects will become obvious as the following description progresses.

In the procedure of decanting solutions from finely divided particles that have settled therein, it is of paramount importance that there be substantially no disturbance of the settled particles. This is especially true in-solutions that are more or less viscous in character.

According to the invention, a container for the solution to be decanted is preferably circular in its configuration along a horizontal plane, and relatively shallow in depth. The bottom of the container has a gentle slope inwardly from the circumference thereof towards the center where the surface drains into a waste discharge pipe.

Centrally disposed in relation to the container is a substantially vertical conduit for removing clarified solution from the container. This conduit has a decanting head havingintake nozzle means disposed transversely of and leading into said conduit. Solid particles that settle out of the solution are, at such times as it is desired to flush the bottom of the container, given a gravity-actuated rolling action along the gently sloping surface of the bottom by means of which there is a confluence of the settled particles around the outside of the solution conduit, this confluence being led into and through a jacket spaced apart circumferentially from the liquid conduit, said jacket having a suitably valved or otherwise controlled outlet leading to such points of disposal as may be desired.

The decantation head is spaced immediately upward of the settling bed, and is so disposed that the solution enters the withdrawal nozzles with practically no disturbance of the particles in the settling bed. This is brought about by the fact that the decantation head has its lowest intake level disposed substantially no lower than the highest level of the said gently sloping bottom surface of the container. The velocity of the outflow is controlled by well known means, such as a valve.

In the accompanying drawing which illustrates one embodiment of the invention,

Fig. 1 represents a front elevation largely in section taken on the line llin Fig. 2; a

Fig. 2, a top plan, a portion thereof being broken away for convenience. I

Referring. to the drawing, the'n'umeral l0 designates a container preferably circular in its horizontal configuration and of relatively shallow depth, this container being adapted to confine a solution I! Thed'epth of thecontainer is shallow relative to its breadth, as illustrated, the diameter thereof being considerably. greater than the depth so as to confine a broad and not deep body of solution. This container'is providedwith a bottom I2, the inner surface of which slopes gently from the circumference towardsthe center where the surface drains into a waste pipe l3 that forms a jacket spaced apart around a smaller pipe I4, the latter constituting an outlet conduit for decanting the clarified solution. The-decanting pipe at its inner end terminates in a nozzle assembly I5 which in this instance comprises a T-fitting |5a having the' 'outfiow nozzles [5b.

These nozzles preferably are beveled downwardly and inwardly of the container .l 0 so as to form an under-cut entrance to each respective nozzle. The under-cut beveled faces of the nozzles are positioned in relatively close proximity to the sloping bottom 12, but so as to leave the beveled entrances unobstructed, and, as'illustrated, with the lowest levels thereof preferably at but .substantially no lower than the highest level of such sloping bottom I2, here the circumference there of, whereby an effective decanting action is obtained without disturbance of particles which have settled out of the solution.

The solution that is to be decanted is conducted 7 into container l0 through a pipe I1 that extends from any suitable source of solution supply. Assuming that solution I I has been admitted to the container to substantially its full capacity, the solution is allowed to remain at rest for a period of time sufiicient to cause any finely divided particles to separate and settle out, finally becoming bedded as indicated at l8 along the sloping bottom l2. In flushing out the bed of. accumulated solids at such times as it becomesdesirable to do so, the solid particles form a rolling mass that gravitates towards the wastepipe 1'3 and finally drains into the same, flowing into a pipe IS the discharge of which is controlled by any suitable means, for example a valve 20. The pipe IS in this instance is connected to the waste jacket l3 by means of a T-fitting 2|, the latter having a stop-cap 22 that forms a seal around the decanting pipe [4. 1

In operation, assuming that the container is filled with solution to be decanted as aforementioned, the solution is left undisturbed for a period of time that varies according to the characteristics of the solution and finely divided solids contained therein. As soon as the period of time required for the desired precipitation of the solids has elapsed, the solution is ready for decanting.

Decanting is accomplished by causing clarified solution I l to flow out slowly through nozzles ISa and down through the decanting pipe M, the outrlow being carefully controlled by means of a valve 23.

The skimming outfiow of the clarified solution is made possible by the unique construction and arrangement of the nozzle assembly [5 of the decanting head. The undercut nozzle faces 15c, together with the nozzle tips 15d, operate to conduct clarified solution into the decanting head, and the disposition of the decanting level relative to the sloping bottom makes effective decanting possible without disturbing the bedded precipitates 18 to any appreciable extent.

In practice, the present invention is particularly useful in separating impurities from cheinical solvents that are used as vehicles for removing the natural fossilized resins from certain kinds of coal. Inasmuch as such resinous solutions have highly viscous characteristics, the separation therefrom of the precipitated impurities offers dimculties that are not easily overcome by decantation apparatus in common use. In connection with this specialized use of the apparatus, it is to be noted that the resin-bearing solution is taken from the extraction apparatus (not shown) forming the subject of my co-pending application for patent filed August 29, 1947, Serial No. 771,214, this apparatus forming no part of the present'invention.

The present application is a continuation-inpart of a copending application filed in my name May 11, 1943, Serial No. 486,606, now abandoned.

In cases, such as the above-mentioned spocialized use, where the solution to be decanted contains highly volatile substances, it is desirable that the container Ill be closed airtight, for example, by means of a sloping roof [6 that funels the volatiles into an exhaust pipe 24 for disposal at any desired point whenever the pressure within the container becomes excessive. Compressed air that, in this instance, is admitted to the container through a pipe 25 coming from a suitable source (not shown) of compressed air, aids in the precipitation of foreign particles from the solution by gently rippling the surface thereof. Normally, communication between the inner space of the container and the exhaust pipe 24 remains shut off, in this instance, by means of a ball valve 26 that rests on a seat 21.

Admission of compressed air through the pipe 25 accomplishes two purposes, first, to cause a rippling along the surface Ha of the solution, and second, to drive any released volatiles out through the valve 26 and into the pipe 24 when pressure in the container becomes excessive.

Frequently, as in the case of the aforementioned resinous solution, which naturally has considerable viscosity, an underslung bottom 28 is added so as to define a space 29 between it and the first mentioned bottom I2. Warm air is circulated through the space 29 by means of, for example, inlet pipe 30 and outlet pipe 30a.

A practical illustration of the operation of the device of the invention as applied in the instance of one of the aforementioned fossilized resins dissolved in its characteristic solution is outlined as follows. Assuming that the container has been filled with the solution, it is left undisturbed for aproximately. 24 hours which allows suspended particles to be precipitated onto the bottom l2. Meanwhile the temperature within the container is kept at between 70.'and F., for example, by warming the compressed air. The clarified solution is thereupon decanted.

Since foreign particles in the solution are precipitated very slowly, the container is made shallow with respect to its transverse dimensions, whereby a hastening of the settling, and thus a diminishing of the settling time, is effected. Because of this, decanting in the manner herein described is necessary, so that the broad bed of foreign matter covering the bottom thereof be not disturbed during the withdrawal of clarified solution.

A specific embodiment of the invention is shown and described herein by way of a satisfactorily operative representative apparatus, but the scope of the invention is limited onlyby the terms of the following claims.

Having fully described the invention, what is claimed is:

1. Decantation apparatus, comprising a container for liquid having substances held largely in suspension therein, said container being adapted for settling said substances at low levels, and having a bottom which slopes gently such that settled substances bed thereon; drain means leading from the container at the lowest level thereof so as to be operative to remove said substances after settling; conduit means for removing clarified liquid from said container; and a decanting head having substantially horizontal nozzle means'leading' into said conduit means, said nozzle means being disposed at a low level in said container immediately above the level of said bottom thereof, for drawing ofi clarified liquid from the said container, said nozzle means having entrances directed toward the bottom of said container.

2. Decantation apparatus according to claim 1, wherein said drain means is largely jacketed around the conduit means; and wherein the conduit and nozzle assembly has a T-configuration.

3. Decantation apparatus according to claim 2, wherein the extremities of the bar of the said T- configuration are undercut inwardly towards the stem of the T to form the entrance to the nozzle means.

4. Decantation apparatus according to claim 1, wherein the configuration of said container in a horizontal plane is broad relative to the depth and substantially circular, and wherein the bottom slopes gently inwardly towards the center to meet said drain means at the intake mouth there- 5. Decantation apparatus according to claim 1, wherein the container is closed, and means is provided to pass compressed air across the contained liquid in a manner effective to produce rippling of the contained liquid along the surface thereof.

HENRY E. LEWIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 729,297 Edson May 26, 1903 1,063,754 Weiss June 3, 1913 1,150,360 Grevemberg Aug. 17, 1915 Number

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