US2570114A - Coagulating apparatus - Google Patents

Description

1951 w. H. GREEN COAGULATING APPARATUS Original Filed Sept. 5, 1947 I N VEN TOR. WczZZer/Y 6/6672,

Patented Oct. 2, 1951 COAGULATING APPARATUS Walter H. Green, Geneva Township, Kane County, Ill., assignor to Infilco Incorporated,

Chicago, 111., a corporation of Delaware Original application September 3, 1947, Serial No. 771,968. Divided and this application August 29, 1949, Serial No. 112,856

6 Claims. 1

This invention relatesto amethod and apparatus for the mechanical flocculation of solids in liquids, with or without the use of a chemical fiocculant.

A main object of my invention is to provide a form of coagulating apparatus whereby or wherein there is set up a patternof flow of a form particularly favorable to coagulation.

A specific object of my invention is to set up in a flocculation, or coagulation, zone or apparatus a plurality of individual coagulating units, each of which, though not separated from the others by partitions or bafiies, maintains a separate zone with a three dimensional flow pattern affording exceptional opportunity for gentle contact of fiocs, or coagulum, and for gentle passage from one zone to another.

Another object is to fiocculate solids in a liquid by a vortex type of agitation, whereby, due to the intricate pattern of flow in all three dimensions without undue turbulence, the solids in the liquid readily aggregate into larger and denser particles than has been customary heretofore.

Another object is to provide a flocculation, or coagulation; assembly which will function equally well with a horizontal or a vertical through flow and regardless of the location of the inlet and outlet. 7

Another object is to provide an apparatus that will set up and maintain in the liquid within a basin or chamber that forms part of the apparatus, a type or pattern of flow that in addition to inducing very numerous particle contacts or collisions favorable to fioc growth also includes in one or more close-d circuit flows all the liquid in the basin or chamber whereby all the volume of the basin is utilized, short circuiting is prevented and a substantially uniform velocity is imparted to the liquid in all parts of the basin.

Another object is to provide, as one member of apparatus of the type referred to, a rotor, the rotor being so fashioned and proportioned and so placed that during operation it will constantly draw in toward itself a major flow of liquid along or in the direction of the shaft onwhich it is maintained and will discharge this liquid radially outward from the shaft and in substantially equal amount in all directions. Other objects of the invention will become apparent upon consideration of the specification and claims which follow. i

In the clarification of turbid liquids, as by sedimentationor filtration, it isoften found that fine solids in suspension in the liquid to be clarifled are exceedingly difficult to remove, being too light to settle in any reasonable time and too small to be retained by any practical filter medium. Liquids containing such fine solids are usually pretreated by coagulation, or flocculation, (the terms usually being used interchangeably) to improve the settling or filtering qualities of these solids. In the coagulation step the liquid, which customarily will be closed, either before or during the treatment, with fioc-forming chemicals, is subjected to gentle agitation for a period of time to alTord repeated contacts between solid particles, or fiocs, in the liquid. Such contacts promote their aggregating, as by agglomeration and ooagmentation, to form larger particles which are conditioned to settle or filter more easily.

One of the oldest and simplest forms of providing gentle agitation is the bafiled basin. Bafiles of various kinds, such as for example the so called round-the-end type, the und.er-and over type, have been widely used for this purpose. However the agitation provided by the changes in direction caused by such bailles is often insufficient for proper coagulation of large flows of liquid.

More recently mechanical fiocculators have come increasingly into use for coagulating liquids. These fiocculators have paddle agitators of the revolving, or sometimes the reciprocating type. The paddles, usually fixed to horizontal shafts, are slowly moved through the liquid to impart thereto a gentle stirring motion. The degree of agitation that may be imparted to the liquid in this manner is quite limited, as the fiocs produced by this kind of agitation are fragile and delicate and subject to breaking up by turbulence.

It was generally found that this type of agitation, in an unbafiied basin, did not prevent liquid from flowing in a continuous horizontal flow along the surface of the liquid, or along the bottom of the basin, or both, from inlet tooutlet, for, due to the character of the particles, not sufficient positive energy could be applied to the liquid with the stirring devices used to break up this tendency. To avoid such objectionable short-circuiting of part of the liquid, paddle agitation usually has been combined with various types of baflle arrangements. By interposing round-the-end or over-under bafiies or the like, the liquid was forced to take a circuitous path which prevented its short-circuiting from inlet to, outlet. Between pairs of battles individual 3 agitation cells, or units, were thus set up, wherein the paddles caused a gentle agitation of the liquid. Thus the general forward flow of liquid through the basin was subject to deflection, laterally or vertically, by the baflles, and to some kind of agitation'in' the individual cells by rota-v tion of the paddles. The combined motions resulted in particle collisions conducive to coagulation. In all such apparatus the most apparent.

and greatest amount of movement orthe liquid in passing through the coagulating space is the continuous longitudinal forwardlmqvement from.. inlet to outlet, the moving paddles. mer'lycaus- 1 ing some local turbulence in this pattern of flow.

Since the greatest permissible velocityof. such paddles is generally considered}toflbef lfi to' '2 feet per second it is obvious that a very elaborate paddle system is required to secure enough collisions to produce maximum coagulation. I have the prior, art, is, a Very. expensive Way of providing coagulation. Moreover the fiocs formedby this treatment arequite fragile and light so, that great careis needed inhandling themtoavoid breaking them up. Another drawback of such prior art structures is that they have generally submerged bearings and that the agitatorsare not accessible for, inspection and repairwithout draining the entire basin.

ItQiS, trhe principal object. of, my invention to avoid these drawbacks and to obtain good flocculation, with .the formation of tougher and heayi er flocs ina cheaper manner. More spe cifically I have found that I can eliminate all bafiies and still maintain what maybecalled selfcontainedagitationv zones which effectively prevent short-circuiting of liquid from inlet to outlet. At the same time I may'provide a structure free of submerged bearings, and which af-.

fords easy access to individualagitators during operation of the apparatus.

These improvements are obtained by using, in-

stead of the paddle agitators of the prior art, a

type T-of rotor which pumps a large volume of liquid and establishes in'the liquid what may be termed a closed cycle vortex, and by mounting and dimensioningsuch rotor, or .rotors, in such a manner that the .vortexorvortices set up embrace the entire liquid 'in the basin. I am aware that rotors of the general type employed herein are not new buthave been used heretoforefor mixe ing of liquid and',chemicals, for stirring liquids to aid in solution of solids or.to keep solids in suspension, for the likeQbut' as far as .I know, they have not been usedin, andnot beenconsidered suitable for, flocculation. The vortex created by'these rotors has not been thought a proper type of agitation for coagulation, as the general theory of the prior art of flocculation was that only very gentle agitation, Without turbulence was permissible. I'believe that-I am the first to discover the advantages of such rotors for the present purpose and the needfor their being properly designed and-placed relativeto' other 4 parts if all possible benefits are to be had, and to disclose the principles and limitations of such design and placing.

I have found that the vortex type agitation is very suitable for coagulation and affords many advantages. over 1 paddle agitation, The number of collisions between particles'of difier'ent size and age which lead to coagmentation and amassment of flocs, is by far higher in this type of agitation. This is due to the intricate flow pattern set up by these rotors, wherein the liquid moveszlin all three. dimensions instead of the simple rotation oflthe prior art of coagulation. Therefore flocs-forrn more rapidly and become .tougher andheavier... Furthermore the vortex set p around a rotor of this type tend-s to maintain itself, i. e. the liquid approaching a rotor on its way through the basin is positively pulled'into, and held for a period of time in, the vortex. It is desirable that the amount of the vortex flow is such that all. liquid-v inl itsuzone of. infiuencellormally passes. at least i twice: through the vortex,

Thusithe. liquidv isdeflected. from its eneralfor: ward flow through the basin from.: inlet;t0..0utlet', thevortex setup by such a rotor accomplishing whatlprionartlhad. to :accomplish by ba1lles.:,. it ipreventsktshortecircuitingl. With. a. rotor, of this type, the direction. .oftforwardlflow' through the flocculationzchamber, is of no importance. Whethen the genera-1;, direction of,.thr01lg1f1, ow be .horizontal, as i. is ;,usual. in separate; coagulat ing. apparatus, or ,vertical, as ,frequently used in a:. fioccu1ation chamber-which is surrounded by asedimentation-chamber...thelliquid willv .be, dc;- flected ;.from the: .forward fiow and; heldtor a period of; timegin-.the;.vortex., Therefore,;.the liquid may entertheflocculation chamber at any convenient, point;.;and be withdrawn from any convenient point, as longas-therotor isinterposed.in-thepat fl e 1 quid;-. on. nlet: g t: let. The. samei :not t ueb mesmeas tetieui where .,a;,definite relation mustb established between th dir n. theg hr ushl fiQw'e et of the rotation set up by the paddles and the inlet, and; outlet therefore carefullylocatedz In; order tO- Obtain ,the'se resultslthe rotor has olb: are u dim n oned-l mi- .P Qm t md a d roper-1v; ols tiqne zinf nrie i qil in the basin. Thus, I have found, for instance, that ,the. relative, length; of, :the, blades to the d me r .of t ero on smrea imp t ce h regard; ate the .flow pattern caused by rotation of the rotor; Too longbladespause the liquid which is drawnz'into the yortex to; flow along the,shaft ol thegrotor, in a very;.ti'ght spiral lthat may. cause breaking up.of flocs;,: Toosshortabladess on; the other. hand, do, not .pump;a sufficient volume of liquid; into. thelvortex to utilize all, theliquid in the ..basin'.;,. I thaveafoundrzthatb the. underwater lengthtof .the blades. may range, .depending on other circumstances, from about one-fourth to about .one-third of the; diameter 1 of the rotor. Similarly .tha'diameter of therotor must be properly proportioned to-thesize of the basinz With arotor mounted onawertibal shaft a'fdiarneter ranging rr mabout one-fourth to about one-fifth the widthor diameter of the basin ha been found satisfactory. It will be und'erstioodj'that suchdimensionsare not sharply critical and'may vary'considerably with such things as the number of blades 7 provided, the shape and dimensions" of the basin, the number of rotors; used and the nature of the liquid to be -treated.- The important thing is that the-flow set-up is of the closed 'cycle vortex typeand embraces substan tiallyall liquid within thesphere of influence of a rotor, the liquid being drawn into the rotor and then thrown outwardly substantially uniformly in all directions.

Obviously, to obtain the same amount of agitation the size of the rotor can be smaller with higher peripheral speeds and must be larger with lowerspeeds. I have found rotors of the dimensions mentioned and with a peripheral speed of 2 to 3 feet per second very satisfactory.

The rotor may be mounted in various ways in the basin. In a preferred form of my invention the rotor is mounted on a vertically extending shaft which may be supported on a beam or arm across the basin, or on a supporting column, in which case I may provide a walkway extending from the side of the basin to the column to provide access to the agitating unit. In one preferred form of the invention the rotor is mounted on a hinged support so that it can be swung over to the side wall of the basin.

With a rotor mounted on a vertical shaft and the blades extending vertically from the under side of a horizontal plate I have found it advantageous to mount the rotor so that the plate is above the liquid level. I have found that when the plate is immersed in the liquid, its rotation will sometimes cause a rotational flow of the surface layers of the liquid around the basin, which is conducive to short circuiting, and that at any rate, the vortex in such case will not extend into the upper layers of the liquid so that no full benefits are had.

My invention will be more fully understood by reference to the detailed description which follows and to the drawings which show preferred embodiments of the invention, and in which like reference characters designate similar elements.

Figure 1 is a plan view of a preferred form of a coagulation apparatus according to the invention, showing two forms of rotor support;

Figure 2 is a longitudinal vertical cross-sectional view of the apparatus of Figure 1;

Figure 3 is a vertical transverse view of a modified apparatus suitable for vertical through-flow and showing a swingable or hinged support of the rotor; and

Figure 4 is a partial vertical cross-sectional view of a coagulation basin with the rotor supported ona column.

The apparatus of my invention shown in Figures 1 to 4 comprises a basin ID of conventional size and shape but without conventional baffles. The basin may be of any desired shape, such as rectangular, as shown in Figure 1, or round, as the embodiment of Figure 3. The basin H] has a substantially flat bottom H and upstanding boundary walls, such as side walls [2 and I3, and end walls I4 and I5, or in the case of a round basin, a boundary wall l6. Ordinarily a walkway I 8, such as is shown in Figure 4, will run along the top of the basin I0. Liquid to be treated may enter the basin in any suitable manner. In Figures 1 and 2 it is shown as entering at one end of the basin as through an inlet 20, discharging into a distribution launder 2|. Treated liquid is withdrawn from the basin at a location functionally remote from the inlet, as through an outlet pipe 24 leading from the other end of the basin. While the liquid is shown in Figures 1 and2 as entering at one end of the basin through distribution launder 2i and as being withdrawn from the opposite end of the basin,- such location of the inlet and outlet and.

the use of a distribution launder do not form an" essential part of my apparatus.

The direction of the through-flow is of no importance as my apparatus lends itself equally well for vertical as for horizontal through-flow. Thus, in Figure 3 the liquid is shown as entering near the bottom through inlet 20a and is withdrawn near the top through outlet 24a, but the location of the inlet and outlet could be reversed and the inlet be near the top and the outlet near the bottom. One outlet 24a is shown in Figure 3 (and in a separate coagulation chamber the inlet 20a and the outlet 24a may be simple pipes extending through the same wall of the basin), but a plurality of ports 24a would be used, or the liquid be permitted to overflow the wall of the coagulating chamber where the flocculated liquid is discharged directly into a surrounding or adjacent settling chamber. Such relative location of inlet and outlet is permissible and no special. means for distribution are needed because the rotor, when properly positioned, will immediately draw the incoming liquid into, and incorporates and retain it in, the vortex fiow wherein it is. mixed with and distributed through at least anequal quantity of liquid undergoing coagulation. The important thing with regard to the relative location of the inlet and outlet is that they are functionally-but not necessarily spaciallyremote from each other. By functionally remote I mean that they are located so that the vortex or vortices set up in the basin are interposed in the path of the liquid from the inlet to the outlet. A drain 25 is provided in the bottom of the tank, so that the basin can be emptied if desired. The inlet 20, outlet pipe 24 and drain 25 will be provided with suitable valves, not shown.

One or a plurality of rotors 30 are provided in the basin [0. While two rotors are shown in Figures 1 and 2 it will be obvious that any number of rotors may be provided andthat the number will be dependent on the size of the basin and of the individual rotor. In small basins a single rotor is satisfactory. Preferably, where several rotors are used and proportioned as above described, they are spaced apart a distance about equal to the width of the basin. This arrangement will establish what might be called tangential vortices-i. e. vortices in which the flow established by each rotor extends over to, and is tangent to, the vortex established by the adjacent rotor.

Each rotor 30 comprises a plurality of vertical blades 3| which may be mounted on any suitable supporting means, such as a spider, but which are preferably mounted on the underside of a plate 32, as shown. The diameter of the plate 32, or other support, may be from about one-fourth to about one-fifth the width or diameter of the basin. The blades 3! may be mounted on plate 32 either radially or at an angle to the radius. Preferably, at least twelve blades are provided. However, the peripheral distance between blades preferably should not be more than from 15 to 20 inches, so that with large rotors a much larger number of blades is desirable. The width of the blades 3| may be approximately one-seventh the diameter of plate 32 and their length from about dicated bythe dotted line L in Figure 2, but the awe,

blades-customarily:wvilhbe substantially immersed in the liquid. Thisiconstruction -is preferred as obviously the plate :32 ewould interfere with; or distort n'the vortex formed by the. moving blades,- and I have foundnthat best results are--seeured --5 whenethe tnatural shape-of-thevortex -is not: changed-and the velocity imparted is relatively uniform-throughout; Also the plate if immerseth would consume additional power" without cor-- responding benefit. As mentionedabove I havealso. found'that whenlthe plate is submerged, the liquid. above the plateis notincorporated in the vortexcbut has a tendency to --fiow-. around i the basin along its walls, which may lead to:shortcirouiting Such a flowis notdesirable and: it is therefore 1 preferred,-: where a plate: is .aused- :for:- supporting vertical blades, to mountit ataneleva w tion above the normalliquid level.

V, Theroton and its driving assemb1y -35,- 35 nlays be supporteddnvarious -mannersl- As shown in ao Figure-1,'at the left, the rotoris supported byfi a beam or bridge Afl which zspansi the: basinj as' shown. The-motor 35 and-speed reducer 36;-=from which the shaft 334s suspended are mounted on the beam MI. -In :the -customary marrow I basin the rotor would be placed atthe longitudinal axisof the basins- Obviously, ina wide-=-basin,a plural-- ity of rotors-maybe supported trom -each' beam 40. The beam 4mm preferably provide :awalkwayiromthe -wall--of: the basin to "the rotor or rotors.-

Another kindof supportis shownzat the righthand end-of Figure--l--,-*and-more-clearlyin Fig: ure In this embodiment of my invention a swingable or hinged; arm or supportis provided for each rotor-motor assembly, so that the entireassembly can be moved over tothewall oi the basinjjor inspection grrepair without-interptinst e: o eration o t e-a p rat S ppo t. may c m ri e. a Y a m. M ich i p v-J al rgm unntedw a W l o the..b siwb.y. a y suitable hingewfi lgand extends over,the,basin; preferably above .thenormal liquid ,level therein A brace 43. maybe. provided -to givesupport to -a m an c@ 50behi ttlli un edionua the basinwalhas by hinge-44; ,The arm" 4|- mayi be held; against: undesired-horizontal amovement by abracket 45, 1 as shown ,Another-meansof. supporting the rotor 3-0 and motoris shown Y inrliiguregl. Here the moterv 5 and rotor derive support from an upstanding: pier or column '5 0 rising; from the floor-1.; of ;the tank;, The shaft,;33ris icentrally' and rotatablyi mounted on the pier andthe-i -plate 32 is amkedm to-the shaft 33,:at an elevationiabovewthe normalif liquid level in the basin.a:= The bladesi3l .iencircle 1 the column and rotate 'thereabout. wPrefera'blycz the column will "extend up.-.to;.anelevation above the normal liquidzlevel toavoid-t'all sub merged bearings. In thiswembodimentz-I may also provide a bridge ilypreferably of. the'rcantieia lever type, as shownin-F-igure 4 extending from the wall of the basin-to the rotor 30.* Inxa largen. basin, where several rotorsare employedl may provide an individual 1 stationary bridge -for each rotor,or, as shown in Figure l, a single movable bridge,- which may-serve; arow of rotors.

Such amovable bridge' may =c omprise--a beam' or arm 52 extendingover the basin toadjacentthe" rotor and also extending ashort distance outside-the basin above the wa1kway-;-l8'. Theouter-end of thearm 52 may be heldin place -by*{-; means of a Z bar ;53 whichmaybe bolted tothej walkway; l8,--as by bolts 54-: -On-top-of theside- & walllter l3 a rail 55 may-be"provided and a wheel- 56- bemounted on theunderSide' Ofthe arm--5 Z'tand positioned to runalong-the rail 55. The arm 52 may be supported-by a brace STFasshown; whichmay-carry a wheel 58 at its-lower end; adapted torunalong the 'insideof the wall"? 12 or l3. The'bridgeil can be moved manually-t or byiany suitable) means, not shown: 1'.

Itwill be'obvious that the motor need notfibe': mounted as ,shown,supported above the basin; but lcanmbe placed. to 'one, side of the basin? and t supportedflin anylsuitable manner,. as ,rrom '.a wall "of. the. basin. Insuch .casev. suitableogear ing will connectv the motor. and, the shaft not the H rotorsand suchgearing, may besupported from V the beamlfill, 'or the arm 4 iorthe column 50, as a the case-may be Alsor the rotorxinsteadaof be-ming-v atrthe-topof the liquid in the basin can-whet ,at a lower: level; i011rinstance-the:shaft::3.3 p0uld-z be extended to thegffioonof the: basinsand; the:v

rotor mounted-near the lower end-in invertedlpositionv'withl the .xbladesi-extendin'g; upwardly: .from the 1.11211653211' This would; invert thervortex; ;the basin iwhich'might'ibe of advantage in some' cases; as tor instance when dealingwith 'relativ'elyheavy precipitate- The ope-ration of my -coagulator willbe-readily understood. Theliquid to be treated in the ljcoagulator customarily is -d0sed with 1 a coague lant-either-beforeits entryinto thebasin inforduring its treatment therein, "or, in. .some in-ii stances, it maybe subjected to mechanical'flo'cculation alone. For? both Lpurposes myHcoagu-H latorwlends itself ,very well. .u 'Liquidto be treated.

may enter the .basin, ,astshown. insFiguresc 1- and. 2, through inlet2 0 V. and, distribution .launder-..-2 I and is displaced forwardly to the outletfend-of-i the basin-and thence into outlets conduit-1:24, "leadingatowa settler, orfilter orstheslikea-nota shownla Or, ,as shownin :Figure 1 3, it may. flow? through-the :basin inra vertical= forward flow; as by entering rat inlet conduit 2 ila-near the-floor. and being withdrawn through out-let conduit-12421 at a'highemelevation; The inlet 20a"and.':;thel.: outletzma may'even be in the :same wall of the basin, as shown in the. figure. From this forwarddisplacement from inlet to outlet the -liquidis repeatedly deflected" and drawn-into; and held for a period of time in, the vortex set up bythe rotor or successive j-rotors. V

Such1a, vortex is distinguished from the'rota +1 tional movement caused bythe usual, paddle agi-t-g; tation by its thre e,.. dimensional flownpattern Whilejflintherotation of paddles throughliquid the. movement of the liquidis always in .the same plane, -in avortex coagulation -the liquid -moves through lnumerousaplanesm The-vortex spatternr has-1a flow? whichaspirals: outwardly in 'all ldire'c-s tionsattthel top to the wallsofthe basin or the, edge of itszone of influenceythen spiralsgdown T wardly to thewfloorysthen: spirals 1 inwardlyirom allidirections :along thetfioortto' the'iaxis :of the": vortexgwwhich'fis substantially the axis-of the-- shaft 33', "and then spirals upwardly along theiaxis' to the rotor; which imparts: the outwardly 1 spiraling flow at -thetop. The axis-of thevortex maysometimes be at right" angles to a general horizontal direction of flow" through the basin onsomet-i-mes, as -in verticaldirection of through flow, maybe-parallel to the flow. The relation of the vortex to "the direction of V flow'" is relatively unimportant: It isimportant, however, that the vortexfiow caused by the rotor 30 is greater than the normal displacement through the basin l0, so that the vortex will overcome the normal forward displacement. Thus any portion of liquid approaching any vortax is prevented from passing across the vortex to the outlet, as it encounters a stronger stream of liquid spiraling counter-currently to the direction of displacement and then back to the rotor. Into this pattern the liquid approaching the vortex is forcibly incorporated and will remain part of the vortex flow for a period of time. Forward displacement from the vortex can only take place at the outside of the vortex flow (spiraling away from the rotor) so that it is impossible for a particle to flow across the basin 7 without becoming incorporated in each succeeding vortex. It should be understood that each vortex is greater in volume and velocity than the forward displacement, and that it either is large enough to extend entirely across the basin laterally, or there will be two or more tangential vortices which extend from side to side of the basin. During the time the liquid is retained in the vortex an unusual opportunity for particle collisions is provided as the particles contained in the liquid are moved through a multiplicity of planes instead of the usual rotation V in one plane.

Another characteristic of a vortex flow is that the velocity throughout tends to be substantially constant. Earlier fiocculators tended to move quite slowly in order to avoid eddies and turbulence, but with a substantially constant velocity throughout the vortex, this limitation becomes less important. Thus the rotors may be driven with a higher speed than is generally thought permissible in flocculation, and I contemplate peripheral velocities from 2 to 3 feet per second. I have. found that with the type of agitation and the flow pattern set up by these rotors some turbulence is permissible and often desirable. This may be due to the fact that the intricate flow pattern set up by these rotors provides such unusual opportunity for the contacting of old and new flocs and thus for building up of flocs' which are tougher and less subject to breaking up than those formed by gentle paddle agitation. However, with the construction of the rotor, as described, higher velocities of the rotor do not cause the same increase in turbulence as would be the. case with similar speeds of paddle agitators. It should be noted especially, that this type of rotor avoids setting up small violent eddies which are conducive to breaking up the flocs.

Each vortex has a tendency to maintain itself and liquid approaching it is positively drawn into it and incorporated into, and held in, the flow pattern of the vortex. Thus any short-circuiting of the liquid in a horizontal flow from inlet to outlet is prevented and in effect a plurality of individual treatment cells are set up. This result is obtained without use of costly baflles or the like, as was necessary in prior art structures, merely by applying a new positive type of agitation, In larger basins, where several rotorsare used, they will be arranged symmetrically so that their vortices cover the entire area of the tank uniformly. The rotors should be close enough together that the vortices will be tangent. This permits some return of particles from a succeeding vortex to a preceding one. This return is gentle and non-turbulent, which scope of the invention.

is difierent from most return of the prior art. The old art of flocculation did not provide for such gentle and unobstructed return flow from a later agitation unit back to a preceding one. Where a return flow was provided in the prior art, it was either along the full length of the treating basin from outlet to inlet end and what was brought back in such case was in the form of sedimented and resuspended flocs whose value for coagulation is doubtful. Or the return flow Was pumped back from unit to unit through narrow slotlike passages, whereby the flocs were in danger of being broken up. Contrary thereto, in the present invention the liquid with contained suspended particles is free to drift gently and unobstructedly from vortex to vortex, forwardly and, to some extent, backwardly. As the liquid is passed from unit to unit the solids, or fiocs, are agglomerated into large, dense particles that have excellent settling and filtering qualities.

When one of the units is to be inspected or repaired, it will be taken out of service without disturbing the operation of the other units. The whole assembly may be swung over to the wall of the basin, if the swingable type of support of Figure 3 is used, or, in the other embodiments, access is had over the beam All of Figure '1,'or the bridge 5| of Figure 4. In any event the units are easily accessible without draining the basin or disturbing operation when repairs become necessary. It will also be obvious that quite apart from the better accessibility it is generally a great advantage of the construction of this embodiment of my invention that it needs no submerged bearings.

Sometimes it is desirable that the rotors be mounted so that adjacent rotors will be rotated in opposite direction, such as rotor 3!] at the left side of the basin H! of Figure l clockwise and rotor 30 at the right side of the basin counterclockwise. I have found that, for example, such counter-current rotation of adjacent rotors is desirable when the plate 32 of the rotor is submerged, although with the plate mounted above the liouid level these rotors may be rotated in the same direction.

It will be seen that the coagulation or iioccu lation apparatus of my invention affords maximum opportunity for fioc coagmentation and amassment with a minimum of structure. The construction of the coagulator is therefore relatively cheap. The floc produced is readily settleable or filterable, being tough and large.

It will be obvious that the embodiments shown and described are only illu trative examples and that mv invention is not limited to the exact construction of these embodiments. Because of the small space required my flocculation apparatus is very well suited for combined flocculation and sedimentation units and it will be understood that such a use is contemplated as coming within the Thus, many changes could be made without departing from the spirit and scope of the invention, and these changes will readily occur to those skilled in the art.

This application is a. division of my copending application, Serial No. 771,968, filed September 3, 1947, now Patent No. 2,546,691, which is a continuation-in-part of my copending application, Serial No. 681,616, filed July 5, 1946, now abandoned.

I claim:

1. coagulating apparatus comprising a basin, an inlet into said basin, an outlet from said basin remote from said inlet and establishing the ,norma'lliquid levelin said basin, and a-rotor interposed in-the pathzof flow from said inlet; tosaid --outlet,- said rotorcomprisin'g a power driven rotatable shaft-extending vertically in. said basin,:; 5. v a horizontal plate afiixedto said shaft and having a diameter substantiallyless thanthe diameter ---of said basin-,andat least twelve vertical blades rigidly mounted-on -the underside of said plate -and-extendinginwardly from theperiphery ofsfldyontcxfiow.

said 'plate-pnly partway to the center of said plate, the underwater length of said blades being greater than their wi th; the number of said blades being such-that the maximum peripheral distance between; individual blades is within the'si l glll ,l ul fill qn yrfimil fi rom sa inletancll range of fromiabou t 1 5:1) about 20 inches.

2.,In aflocculation basin provided with an inlet and an outlet functionally-remote from said inlet, an i mprovedj; flocculating assembly shaft at a predetermined speed, and a liquid impelling member afiixed to said shaft, saidmember having a diameter substantially smaller than the and theiriwidthless than thein-leng thg 'and means fonrotating said-motomat a: :predetermined;speed, the:pumping;icapaicitygofgsaidn'otomat .zsaidznreetermined speed-shamesuflicient, tdzsetzupn a e=dime s enal-rv rtem fl wrpt a ma n ;substantia-lly in excess of the rnormak rated .fihrqllgh eflow- .randytq positively deflect itheri-iq-uid ,,;-t0 be treated from its-.@f0r,Ward.- flow from said 3 inlet, to sa-id-outlet .-and,-to incorporate it, in said .An ap aratusrf rld velo in flocslofu a charact rlfavorablato. rapidsedim'entation .cornpris- .ing .a,,.00a u1ation. chamber. .havipgnan-imetjor liguid to be treated and an outlet; for' tr eated tablis hing thenormal liquid level in saidlbasin, ,said basin being free 'of partitions "obstructing flow from, said inlet to :Saidnutlet, arotor inter- DQSBdiIl the path of flow-from said 'inlet-to-said comprising a rotatable vertical 'shaft-extendingfl 11 t; ai 1 1 p s la ih l l'"p a e and a; plurality of-verticalblades-mounted on the ""lallldflll'SldB'Of said plate and extending inwardly "from the-periphery of said plate, the'di'ameter bf-said plate being-substantially smaller than the diameter of the basin and having a plurality widthbf said basing-the length of said blades of vertical blades rigidly aflixed to and radially predetermined speed being several times the vol-'="- ume of, the rated ;f1o\v -of liquid fromsaidinlet to said outlet. a

3, Apparatus for --coagulating liquids comprising a basin adapted to h01d liquid tobe coagubeingsubstantially less' than the diameteriiof said plate and -theirwidth lesslthamtheiralength, means 1for rotating-Psaid;rotomwithl. a zpefipheral velocityilwithin lthe. rangero'f :fromi two 'rto: three 0 feet per second, said rotor, upon itsmotatiomat such velocity, :setting 1; ups; afcthree-dimensional closed cycle flow of: a. magnitudeiatzleastrtwice the normal IatEGithI'OUgII-JfiOW.

-' 6. An apparatus for; coagulation comprisingza lated and having an inlet at oneendthereof and 1 basin, a liquid"inlet'to'saidbas maiiiquidiQutlet an outlet at the other end, said basin being free of partitions obstructing-flow therethrough, a plurality of coagulating units, each unit comprising a vertical rotatable shaft; a rotor'afiixed from said basin-".functionallwspacedfronnsaid 'inlet, said'basin being:fizeecgof partitionsziinterposed in the'path of flowiofliquiwfrom: saidainlet to said outlet, a plurality 'of rotors finisaidrbasin,

to said "shaft, saidrotor having a plurality of each rotor including a verticalzsha-ft;azhorizontal vertical blades surrounding ;Said shaft in spaged relationship and being so constructed and arranged as to cause on rotation of said-shaft; a closed cycle vortex in liquid in said basin, a supplate rigidly afiixed 11303 S&ld*ShHft,5JaI1d1 aiiplurality of vertical blades:affixed:torthe underside of said plats and: extending within' the 'liquid -in said basin, the .length :of saidr.blades'-ibeingizless port for said shaft and means for driving -said=% than'the'diameter.of1sajid-rplateandthein'Width shaft, said coagulating units being symmetrically disposed in said basin in spaced relationship in such manner that the entire area of said basin is covered uniformly by the yortices set up by rotation of said rotors and that adjacent vortices are tangent.

4. In a coagulating apparatus comprisinga coagulation basinhaving an inlet for 1iquid -to be treated and an outlet for treated liquid, sa-id said; inlet to said outlet andbeing free of partitions deflecting said flow, unitary means effect- --ing coagulation and preventing short-circuiting ofliquid from said inlet to said outlet, said means 7 consistingin a rotor assembly interposed in the? flow from-said inlet to said outlet, said rotor assembly having a diameter substantially smaller than th.-Width of" said basin, and comprising a -Nertical shaft axially extending in said basin, a

horizontalplate rigidly secured to said shaft,-

vertical blades mounted on the underside of said plate; and extending inwardly from its periphery only partway to said shaft, the length of said blades-being less than the diameter of the rotor 70 2,128,447

, providin a path for forward fiovv from:-

WALTER H. GREEN.

I ?REFERENCES:YCIT ED "The following references are of record in the file, of this patent: l

UNITED? STATES PATENTS Number Name 7 "Date 544,996 Schultz et"a1.' Aug-220j '1895 656,217 Roettinger et ;a1. Aug? 2 11 "1900 1,605,596 'Langelier I l Novi 2; I926 2,081,851 Darby et a1 May '25; 1937 Wright AugQBO, 1938

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