US3291316A - Feed means for clarification apparatus - Google Patents

Description

Dec. 13, 1966 E. M. KELLY FEED MEANS FOR CLARIFICATION APPARATUS 2 Sheets-Sheet 1 Filed Sept. 25, 1963 INVENTOR.

EARL M. KELLY BY WTTORNEY Dec. 13, 1966 E. M. KELLY FEED MEANS FOR CLARIFICATION APPARATUS 2 Sheets-Sheet 2 Filed Sept. 25, 1963 INVENTOR.

' EARL M. KELLY BY WQJM ATTORNEY United States Patent 3,291,316 FEED MEANS FOR CLARIFICATION APPARATUS Earl M. Kelly, Hillsborough, Calif, assignor to The Eimco Corporation, Salt Lake City, Utah, a corporation of Delaware Filed Sept. 25, 1963, Ser. No. 311,391 4 Claims. (Cl. 210520) This invention relates generally to clarification of turbid liquids and in particular to improved apparatus and method of operation enabling full use of the clarifier tank volume and area to the end that its clarification capacity is increased over that normally attainable in tanks of the same configuration.

Clarification efficiency is affected deleteriously by the establishment of positive flow currents with-in the clarifier tank which act to rapidly convey (short circuit) a significant portion of the incoming turbid liquid directly to discharge thus depriving it of the detention needed to carry out separation of its suspended solid content.

Prior attempts to overcome this problem have included the use of larger tanks to insure that the turbid liquids, even when entrained in short-circuiting streams, are detained sufficiently long to permit sedimentation of solids. The inevitable result is a loss in clarifier efficiency due to over-detention of a major part of the turbid liquid feed beyond the time required for its proper clarification.

It has long been known that proper distribution of the clarifier influent adjacent the periphery of the clarifier tank coupled with the ultimate discharge of clarified effluent adjacent the tank center would result in improved operation. A most important reason is that, in such an arrangement, the incoming feed is distributed over the greatest area of the tank (at the periphery) whereby its flow energy is more thoroughly dissipated and the danger of establishing positive flow currents is minimized.

A variety of structures have been proposed to take advantage of this knowledge. Some structures utilize skirts or bafiles arranged around the periphery behind which incoming feed is directed and under which it flows into the main sedimentation area in the tank. Still other structures utilize rotating arms to carry the feed to the bottom peripheral area of the tank. Although such prior arrangements havefound some acceptance and have proven useful in certain situations, they are still not all that is to be desired from the standpoint of broadly applicable commerc ial operation. This is so because inlet streams introduced through fixedly located openings or orifices are inherently adapted to the establishment of positive flow currents between the fixed inlet point and the discharge point thereby contributing to short-circuiting of turbid feed liquid.

Previously proposed moving feed structures discharging the incoming feed onto the peripheral tank bottom have likewise proven inefficient because they constantly agitate and disrupt the already settled light flocculant sludge. Hence, such structures hinder rather than help clarification. This is unfortunate because introducing incoming feed adjacent the bottom peripheral tank area is indeed the logical way to insure the longest possible travel, and concomitantly the greatest detention, between feed introduction and eventual discharge. However, agitation of the already settled sludge as well as the fact that the currents introduced through such devices are relatively strong in the proximity of settled sludge have rendered this type of device unsuitable except in situations where relatively heavy sludges are encountered.

It is, therefore, a primary object of the present invention to provide clarification equipment into which incoming feed is introduced at the tank periphery in such a manner that the flow energy of the feed stream-s is continuously dissipated in a large volume of quiescent liquid and positive-flow currents following a fixed path can neither be established nor maintained whereby agitation of previously settled sludge is completely avoided.

Briefly, the invention revolves about the concept of introducing incoming feed through continuously moving inlet ports submerged adjacent the peripheral tank walls but at a depth well above the previously settled sludge; and directing such incoming feed substantially parallel to the tank walls and bottom.

In the preferred embodiment of the invention, the feed is introduced through hollow rotating arms which terminate in submerged ports adjacent the tank wall at a median elevation. Preferably, each hollow arm has two feed outlets arranged to be directed in diametrically opposed paths parallel to the tank walls whereby only counter flowing currents can be initiated (and these are immediately neutralized). Also, since the arms and associated feed ports move continuously in the relatively large volume adjacent the tank wall, influent feed energy is thoroughly dissipated. Moreover, creation of fixed-flow currents is avoided because there are no fixed points between which currents can be established. By locating the inlet ports at a mid-depth (i.e. in submergence, but well above settled sludge) and directing the feed substantially parallel to the tank walls and bottom undesirable agitation of sludge is avoided.

Thus, it may be said that the basic method invention hereof comprises the steps of introducing feed substantially parallel to the tank walls and bottom through submerged ports located well above the tank bottom and adjacent the tank periphery.

The basic apparatus invention comprises, in a preferred embodiment, a clarifier with rotating arms adjacent the tank bottom through which feed is introduced and which have, adjacent their outer ends next to the tank wall, feed ports arranged to direct feed parallel to such wall and the tank bottom, the arms being mounted to be rotatably driven over the tank bottom whereby the feed ports move continuously through the tank contents.

In order that the invention may be more readily understood and carried into effect; reference i made to the accompanying drawings and the description thereof which are offered by way of example only and are not to be taken in limitation of the invention, the scope of which is defined by the appended claims rather than by any preceding description.

FIG. 1 is a top plan view of a clarifier embodying the invention.

FIG. 2 is a side sectional view of the clarifier of FIG. 1, certain parts being shown in elevation for purposes of clarity.

FIG. 3 is an enlarged isometric view of a portion of the feed distributing and rake arms of the clarifier shown in FIGS. 1 and 2.

FIG. 4 is an enlarged elevational view, partially in section, of the center structure of the clarifier of FIGS. 1 and 2.

Referring now specifically to the drawings, there is shown a clarifier tank generally designated 10 constructed with a sloped bottom 11 and upstanding marginal sidewalls 12. Infiuent is supplied to the tank via conduit 13 for distribution in a manner to be hereinafter described in more detail, while settled sludge is collected in a sump 14 and discharged through a suitable conduit 15. Clarified liquid or effiuent overflows into a centrally located annular trough 16 suspended beneath a bridge 17 in turn supported by a central pier 18 and the tank wall. Efiluent from the launder 1-6 is carried from the tank via a suitable conduit 19.

On the bridge 17 is mounted a drive mechanism 21 which is in turn functionally connected to a rotating torque tube or drive column 22. Attached to and rotatable with the drive column are hollow arms 23 which serve the dual function of carrying incoming feed to the periphery of the tank and raking settled sludge to discharge.

The raking is accomplished by means of spaced-apart rake blades 24 secured to the bottom of the arms 23 and positioned to continuously rake solids inwardly toward the center of the tank as the arms rotate.

Feed distribution is accomplished by means of a particular arm construction which includes a hollow center portion 26 (FIG. 4) an end portion in the form of an upwardly flared or U-shaped section 27 extending from the arm itself and terminating in oppositely facing submerged ports 28 spaced well above the tank bottom and arranged to direct emitted streams horizontally and substantially parallel to the tank walls (e.g. perpendicular to the axis of the arms).

Incoming feed enters through conduit 13 whence it passes up into the base portion of the central pier 18 thence outwardly through ports 29 into the space 31 between the torque tube 22 and the center pier 18 to flow outwardly through the hollow interiors 26 of the arms 23 to finally discharge through the ports 28 adjacent the tank wall.

As i usual in such construction, the torque tube 22 is provided with a concentric seal, generally designated 35, adjacent the bottom of the center pier 18. This may also serve as a steady bearing in known manner.

With particular reference to FIGS. 1 and 3, it will be noted that although the incoming feed is introduced in stream form parallel to the tank walls, the volume of liquid above, below and inwardly of the inlet ports 28 is so great that the inlet energy is immediately dissipated. Since the ports are located at mid-depth, the hydraulic head is considerably lower than if the ports were at the bottom and this reduces inlet force. Moreover, the continuous motion of the arms results in constantly changing inlet locations with the previously noted advantage of eliminating positive-flow short circuit streams.

In the preferred embodiment illustrated, the feed is emitted from each arm in opposed streams thereby further dissipating energy.

The overall result is substantially complete ultilization of the entire tank volume with uniform detention of all incoming feed from the time it enters the tank until it eventually reports to overflow. Since there are no positive flow streams in the tank, there is no need for excess tank capacity to accommodate them, consequently the clarifier tank for a given throughput may be proportionately reduced. Stated another way, clarifier efficiency is increased hence an existing tank can handle a greater flow to yield properly clarified efiiuent or, in a new installation, smaller equipment can be used to handle a given flow.

From the foregoing it will be evident that the present invention provides ways and means enabling the economic clarification of turbid liquids by which clarifier tank efficiency is maximized by the elimination of short circuits through the medium of substantially killing all incoming feed energy by distributing the feed at a mid-depth adjacent the tank wall through ports that are constantly moving relative to both the walls and the bottom.

I claim:

1. In a clarification apparatus of the type including a sedimentation tank, a sluge outlet in the lower portion thereof, a liquid-level defining efi'luent outlet in an upper central portion thereof and feed introduction means, the improvement comprising a feed introduction means having a rotatably mounted hollow arm extending radially from the center of the tank in closely overlying relationship to the bottom of the tank and terminating upwardly adjacent the periphery of the tank, and a plurality of feed inlet ports located at the upwardly extending end of said hollow arm to introduce feed at a medium elevation inter mediate the effluent outlet and bottom of said tank and sufiiciently above the tank bottom to prevent agitation of settled sludge, said ports adapted to discharge feed liquid adjacent the tank wall and in a plane substantially perpendicular to the tank axis. A

2. The clarification apparatus of claim 1 wherein said fed inlet ports terminate in opposed directions.

3. The clarification apparatus of claim 2 wherein said oppositely directed port are formed of a U-shaped conduit extending upwardly from the hollow arm.

4. The clarification apparatus of claim 3 wherein said feed introduction means further includes sludge rake means attached to said hollow arm.

References Cited by the Examiner UNITED STATES PATENTS 2,263,168 11/1941 Dorr et al 210-520 2,267,516 12/ 1941 Adams 210520 X 3,025,966 3/1962 Kivell 210520 3,036,715 5/1962 Gould 210520 REUBEN FRIEDMAN, Primary Examiner. I. L. DE CESARE, Assistant Examiner,

Claims (1)

1. IN A CLARIFICATION APPARATUS OF THE TYPE INCLUDING A SEDIMENTATION TANK, A SLUGE OUTLET IN THE LOWER PORTION THEREOF, A LIQUID-LEVEL DEFINING EFFLUENT OUTLET IN AN UPPER CENTRAL PORTION THEREOF AND FEED INTRODUCTION MEANS, THE IMPROVEMENT COMPRISING A FEED INTRODUCTION MEANS HAVING A ROTATABLY MOUNTED HOLLOW ARM EXTENDING RADIALLY FROM THE CENTER OF THE TANK IN CLOSELY OVERLYING RADIALLY SHIP TO THE BOTTOM OF THE TANK AND TERMINATING UPWARDLY ADJACENT THE PERIPHERY OF THE TANK, AND A PLURALITY OF FEED INLET PORTS LOCATED AT THE UPWARDLY EXTENDING END OF SAID HOLLOW ARM TO INTRODUCE FEED AT A MEDIUM ELEVATION INTERMEDIATE THE EFFLUENT OUTLET AN BOTTOM OF SAID TANK AND SUFFICIENTLY ABOVE THE TANK BOTTOM TO PREVENT AGITATION OF SETTLED SLUDGE, SAID PORTS ADAPTED TO DISCHARGE FEED LIQUID ADJACENT THE TANK WALL AND IN A PLANE SUBSTANTIALLY PERPENDICULAR TO THE TANK AXIS.

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