CA2460123C - Apparatus and method for producing small gas bubbles in liquids - Google Patents

Abstract

An apparatus for creating microbubbles of gas in a liquid. A vertical pipe member is adapted to receive a liquid-gas mixture having gas bubbles of larger diameter therein. A
series of horizontally-extending apertures are provided to permit the pipe member to expel such liquid-gas mixture radially outwardly from such pipe member. The expelled liquid-gas mixture may contact the sides of a containment vessel. In a refinement of the invention, a specific relationship is further specified between the exit area of the apertures and the interior cross-sectional area of the pipe member, in order to most suitably convert the gas bubbles in such liquid-gas mixture to microbubbles of a desired small size when expelled under pressure from such pipe member via such apertures. A method of converting gas bubbles in such liquid-gas mixture to gas microbubbles is further disclosed.

Description

APPARA'~'l1S AZVD ME~.'I~i~If ~'Cfl~ Pt3l~UC~P'~G
~~ta~.~ ~A~ ~u~~L~s ~~ ~,~~u~.ns Fieid of the Inventinu S The present invention relates to an apparatus and method for aeration and purification of liquids, and more particularly to an apparatus and method for producing small gas bubbles in liquids for purification and aeration of said litluids.
8ackgronnd of the Ixtventintt 11~ Entrainment of a gas in a liquid is required in numerous industrial processes, typically for the purposes of reacting tlzc gas with such liquid or materials in such liquid, such as dissolved ions or fir<ely dispersed solids, to cause reaction of such gas with materials therein to cause same to be neu~aIi~.ed by, xeact with, or precipitatE or be filtered out of such liquid-15 For example, it is known to bubble o;cone through water, to allow the ozone to react and combine with dissolved minerals andlor finely dispersed solids within the water, so as to form solid pxoducts which may either precipitate out of the liquid or be filtered frarn the water, so as to thereby purify the water. 'The ozone may further react with ~.arx~ful bacteria or the like in the water so as to render them harmless or odourless.
Where a gas is desired to react with a liquid or finely dispersed solids in such liquids, it is widely known that small bubt~les of gas immersed in such liquid will have, for the same volume of gas, a greater surface area and thus a greater liquidlgas interface, than the same volume of gas when such gas exists in larger bubbles.
A large gaslliquid interface is a desirable characteristic tat instances where the gas is introduced into a liquid for the purposes of reacting the gas with the liquid or dispersed solids iu such liquid, since greater surface area of the gas exposed to such liquid andlar finely dispersed solids izt such liquid decreases the time it takes for the gas to react with the liquid or finely .. 1 ..

dispersed solids within such liquids, thus allowing quicker processing. As well, a lesser amount of gas, and smaller containment vessels, can thus be used, resulting in cost savings.
The benefits, therefore, of introducing or entraining very small bubbles of gas, typically in the range of 50 to 100 microns in diameter, into a liquid for the purposes of increasing the surface area of the gas relative to the liquid (and/or finely dispersed solids in such liquid) are known. Small bubbles of this size are generally referred to in the art as microbubbles. For the purposes hereinafter of this disclosure, microbubbles will be referred to and will be understood as meaning gas bubbles of a diameter in the range of 50 to 100 microns, and preferably 5 to 50 microns.
A number of devices .and methods for aerating liquids, typically water, with gas bubbles, are known.
For example, US 2,850,838 teaches a device for filter-separating iron from water. Water is delivered via a pipe 13 to an air aspirator 14, and thereafter such water having air entrained therein is delivered via pipe 16 to the upper portion of a tank 10, where it passes vertically downwardly in the tank 10 to a spray valve 19. At the spray valve 19 the water-air mixture flows outwardly through openings 21 into chamber 22 formed in a cylindrical hollow body 23 mounted on valve 19. The upper end of the body 23 is cone shaped, and contacts the mating lower cone-shaped end 25 of valve body 26. The water-air mixture flows upwardly and outwardly through the cone-shaped opening formed between cone-shaped surfaces 24,25 in the form of a vaporized spray S, as shown in Figures 2 & 4 thereof, and mixes with the air in the tank 10 as it strikes the underside 27 of the top 28 oP the tank 10, thereby introducing air into the liquid which in turn oxidizes metabolic iron presf;nt in the water. Iron precipitates then settles out of solution and down through the water contained in tank 10.
US 5,601,724 and US 5,460,731 teach an apparatus and method, respectively of aeratiing liquids. Figs. 1 & 2 of each of '724 and '731 show a venturi air injector 10 used to inject air into water in a conduit 12. Such air-water mixture enters the bottom portion of a tower-like pressure vessel l~, where it is directed ttpw~trdly via conduit 30; where it is directed through a cylindrical restriction gap 19 formed between the secand end 34 of conduit 3~D and the tap 1.8 of vessel 14.
The gas, being of lesser density, passes more quickly through the restriction, thereby accelerating the liquid. As the liduid exits the restriction gap 19 it pzzeutn.atically hammers against the top 18 of pressure vessel 14. Thereafter the liquid stream, by farce of gravity, cascades through the gas in pressure vessel 14 downwardly to further impact plate 3~. TheTeafler the liquid stream then passes iluaugh openings 37 in plate 3S and by force of gravity cascades throw the gas in pressure vessel ~4 to further impact on liquid at the bottom of the vessel_ Thereafter such liquid, having small bubbles of air entrained therein, is retnaved via a conduit from the bottom of vessel 1~_ US S,fJ96,Sg6 to a "Process grad Apparatus far Removal of Mineral Contaminants from Water" teaches a pressurized aeration tank 24 having a tube :'6 located within said tanfc 24 which supplies the tank 2a with raw water, which is introduced to t:he tax~3c 24 via the tube ~6 via a plurality of hales 28 in the tube (ref. cal. 2, lines 49-54 and Figs. 1-7).
The tube 24 only supplies "raw water" and not water having air bubbles entrained therein, arid is not for the purpase of providing gas micrabubbles of a range of S-50 microtxs_ Most importantly, no relationship regarding the size ~af the boles ~8 in the tube 24 is specified to attemtpt to attain micrabubbles, even iF the patent further provided far the raw water to 1'xrst have bubbles introduced therein, US 4,556,523 teaches a microbuhhle injector usable to .<separate material of different density by flotation, wherein microbubbles of gas are inuoduced unto a chamber 14 containing a liquid mass 16. As may be seen from figure 1 of US ° 523, a gas atitnixture device 4 receives air through an inlet 6 and ordinary water through an inlet 8. The resulting air-water mixture is supplied by a conduit to the bottom of chamber 14, where it passes through an injector wall ~~
via aft injector hale 1.~ tv procure a high velocity jet of air water. A, deflector wail 18 is disposed over such injector hob so as to create a narrow gap around the injector hole, which the waterlair mixture must pass through. The injector hale is preferably substantially circular, and the height wg_ of the passage between the injector and deflector wall at the ed~'e of the injector hole is less than one quarter of the diameter of the injector hale in the injector wall-Disadvantageously, none of the aforetnentiaized patents teach or disclose any specific design interrelation betweetz the dimensions of the injector holes~rpartslor gaps arid the conduit outer dimensions which will best produce micrabubbles its the liquid-For exartiple, ~JS '838 simply provides a nut 23 an the end of the valve 24 to adjust the size of the aperture between cone surfaces ~4,2a throw which the water must pass. Na gap l~ dirne~nsion is ever specif ed which best provides bubbles of a desired small size.
Similarly, each of US '7~4 and '731 simply disclose that the size of the restriction gap 19 required is dependent upon the size of the bubbles that are produced, with no direction as to what gap size will produce microbubbles in the range of less than 100 microns.
These two patents each ga on to note that (at cal. 6, lines A~ to 47} that the greater the diameter of the cylindrical edge, the closer the end of conduit 30 had to be positioned to the tcap ~g of the pressure vessel ~a (i.e. the smaller the restriction gap had to be} in order to form bubbles of the desired site. No desired size of bubbles was ever identified, nor was there ever any relationship specified between the gap size and the diameter of the pipe, which would produce the smallest bubbles, nariiely 2Q microbubbles of diameter in the 5-attU micron range.
US 4,556,23 perhaps comes closest to specifying an ixrterrelation between the components in order to achieve desixed small microbubble size in the range of 50 to 1~0 microns, speci#'ying as zioted above that the passage between the injector and deflector wall at the 2S edge of the injector hole is less than one quarter of the diameter of the injector hole in the injector wall. No specific optimum site was specified- Moreover, the particular manner by which the microbubbles are created, namely requiring an injector wall lil and deflector wall 14, requires substantial q~taniity of material, aald is thus a particularly material-intensive design and thus relatively costly.
_q Accordingly, a clear and real need exists for an aeration apparatus of simple and relatively inexpensive design having a configuration wherein the size of the flow aperture;(s) through which a gas/liquid mixture flows can be accurately designed so as to give microbubb~les of the desired small size.
Summary of the InvE~ntion In order to meet the above need for a device of simple and relatively inexpensive design able to introduce gas microbubbles into a liquid, in a broad aspect of the present invention such invention comprises an apparatus having means for creating microbubbles in a liquid, comprising:
means for introducing gas bubbles, the majority of which are of a size greater than 1.00 microns, into a liquid to from a liquid-gas mixture;
elongate, hollow pipe means, substantially symmetrical in cross-section of interior cross-sectional area, positioned substantially vertically, adapted to receive said liquid-;;as mixture under first pressure and supply said liquid-gas mixture to aperture means, said pipe member having plug means situate at a lowermost distal end thereof for preventing egress of liquid vertically downward from said distal end;
said aperture means situate on said pipe means and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means and extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said liquid substantially horizontally out~,vardly from said pipe means; and a containment vessel., to capture said liquid-gas mixture having microbubbles of ;;as entrained therein.
Importantly, however., and quite surprisingly, it has been further discovered that for an apparatus of the above design, that in the case of a pipe member that has a symmetric cross-sectional area and a unifornn pipe wall thickness, and a maximum interior width Di and a maximum exterior width Do, a specific inter-relation need exist between the aperture exit area Ae of the aperture(s), and the interior cross-sectional area A; of the pipe means, in order to achieve creation of microbubbles of the desired small size, namely in the range of 50-100 microns and preferably in the range of 5-50 microns.
Accordingly, in a highly preferred embodiment, where the aperture means consists of at least two apertures, the pipe means is symmetric and has substantially identical moments of intertia about two axis in a plane of cross-section through said pipe, wherein the combined aperture exit area Ae of the apertures is a function of widths D; and Do , namely Ae is no greater than A; x D; / Do, Where only a single aperture is used, it has been found that Ae must not be any greater than Ai x Di/2Do.
While the above interrelation, namely for a plurality of apertures where Ae <_Ai x Di/Do and for a single aperture Ae <_Ai x Di/2Do, means it is possible to utilize apertures whose total combined cross-sectional area Ae is less than Ai x Di/Do or Ai x Di/2Do, typically, due to the desire to utilize an apparatus which utilizes the largest flow rate possible, it is usually greatly preferred that the greatest possible aperture exit area be used. Accordingly, more than one aperture will typically be desired to be used (thus the aperture exit axea Ae may be twice as large than if only one aperture were used), and further that the aperture exit area Ae equal Ai xDi/Do, as such will give the greatest "throughput" of liquid which can be provided with gas microbubbles over a given time.
Accordingly, in a highly preferred embodiment, the pipe means will possess more than one aperture, and the exit area of the apertures will be equal to Ai x Di/Do.

In order for the above formula of Ae ~i x Di/Do apply for pipe members having more than one aperture, it is necessary that the pipe member be not only symmetric in cross-section, but further it have substantially identical moments of inertia about two axis in a plane of cro~ss-section through said pipe. This encompasses pipes having circular, square, hexagonal, octagonal and the like having uniform cross-sectional shape, but not to pipes having, for example, a rectangular cross-section. As more fully explained in this disclosure, for geometric cross-sectional areas which although symmetric but which do not have identical moments of inertia about at least two axis of a plane of cross-section, such as for rectangular pipe, such formula does not hold true, and other inter-relations may apply. However, in the case of rectangular pipe of uniform thickness, as is more fully explained below, it has been discovered that the required interrelation between exit areas of the apertures Ae, the dimensions of the pipe, and the cross-sectional area Ai of the pipe for microbubbles of the desired size to be produced be defined as Ae <_A; x [ D3 + D4 ]/[D~ + Dz]
where D~ is the major exterior side length, D2 is the minor exterior side length, D3 is the major interior side length , and D4 is the minor interior side length. However, as rectangular pipe: is difficult to acquire, the more common application of this invention will be to pipe members having circular or square profiles which have identical moments of inertia about two or more axis in the plane of cross-section.
Accordingly, in a highly preferred embodiment, the pipe means of the present inventiion is of uniform wall thickness and has a maximum interior width D; and a maximum exterior width Do , further having identical moments of inertia about at least two separate orthogonal axis in a cross-sectional plane through said pipe means; said apertures having a combined cross sectional exit area Ae defined as a function of widths D; and Do and said cross-sectional area A;
of said pipe means, wherein ~~ is substantially equal to A; x D; / Do.
It is highly preferred, although not absolutely necessary, that there be a vertical surface which created jets of gas/liquid mixture which exit from such apertures may impact against, in order to assist in the creation of microbubbles of gas within the liquid.

Accordingly, in a further refinement of the apparatus of the present invention, such apparatus further consists of substantially vertical surface means adapted to be impacted by said liquid when said liquid i.s directed horizontally outwardly from said pipe means by each. of said apertures.
It is further preferred, although not absolutely necessary, that the collection vessel for containing the resultant liquid having microbubbles contained therein form part of an rote~~al structure with the pipe means and together form a single containment vessel in which the pipe means is located. While there are a number of advantages to using an integral containment vessel having the pipe member therewithin as explained later within this specification, including the ability to create microbubbles within the gas/liquid mixture under an ambient gaseous pressure within such containment vessel, one particular advantage is that, if desired, and if the gas/liquid mixture in the pipe; means is expelled from the apertures under sufficient pressure, the sides of the containment vessel may be used as the vertical surface against which the horizontal streams of gas/liquid which exit the apertures may be directed.
Accordingly, in a further broad embodiment of the present invention, the apparatus of the present invention comprises a vessel adapted to be positioned substantially vertically and adapted to contain a volume of gas in an upper portion thereof; means for introducing ;gas bubbles, the majority of which are of a size greater than 100 microns, into a liquid to forrn a liquid-gas mixture; elongate, hollow pipe means within said vessel of interior cross-sectional area A; , for conveying said. liquid when in a pressurized state to an interior of said vessel, substantially symmetrical in cross-section, situate centrally in said vessel and proximate said upper portion of said vessels and extending substantially vertically downwardly within said vessel from said upper portion thereof, and having plug means situate at a lowermost distal c,nd thereof for preventing egress of liquid vertically downward from said distal end; and at least two apertures situate on said piI>e means and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means, extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said liquid under pressure substantially horizontally outwardly from said pipe means.
_g_ Again, in a preferred embodiment, where symmetrical pipe means such as a cylindrical, square, hexagonal, octagonal, or even a triangular (equal sided) pipe member is used, the apparatus of the present invention comprises:
i) a containment vessel adapted to be positioned substantially vertically and adapted to contain a volume of gas in an upper portion thereof;
ii) elongate, hollow pipe means for providing said liquid to an interior of said vessel, having a longitudinal axis and substantially symmetrical in cross-section so as to h<~ve identical moments of inertia about at least two separate axis in a cross-sectional plane through said pipe means, of uniform wall thickness, and having a maximum interior width D; and a maximum exterior width Do and an interior cross-sectional area A; , said pipe means situate substantially centrally in said vessel and proximate said upper portion of said vessel and extending substantially vertically downwardly within said vessel, adapted for supplying a pressurized liquid to an interior of said vessel, and having plug means situate at a distal end thereof for preventing egress of liquid vertically downward from said distal end;
iii) at least two apertL~res situate in said pipe means and disposed in one or more plmes each substantially perpendicular to a longitudinal axis of said pipe means, each extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said liquid substantially horizontally outwardly from said pipe means, of combined cross-sectional exit area Ae; and iv) said combined aperture exit area Ae of said apertures, defined as a function of widths D; and Do and said cross-sectional area A; of said pipe means, wherein Ae is no greater than, and preferably equal to, A; x D;/Do The apertures) may be of any geometric shape in cross section, such as circular (ie cylindrical apertures), provided the exit area of such apertures) in such pipe member meets the requirement for exit area Ae as discussed above in order to create microbubbles of a size in the range of 50 to 100 microns, a:nd preferably 5-SO microns. In particular, the apertures may be one or more narrow horizontally--extending rectangular slots, or alternatively one or more vertical slots in such pipe member, all of which are easy to manufacture, either by drilling in the case; of cylindrical apertures, or cutting/milling in the case of vertical or horizontal slots.
Importantly, it has further been discovered that apertures in the pipe member of a maximum dimension in excess of a certain amount may not form microbubbles of the required small size (5-50 microns).
In particular, the maximum gap "G", namely the maximum cross-sectional dimension that the aperture may possess is a function of the inner cross-sectional area of the pipe member divided by the outer circumference of the pipe member.
Accordingly, in such cases, where the apertures) are of a horizontally extending rectangular slot, of vertical depth G, where the pipe member has an exterior circumference C, G
should preferably be no greater than Ai/C in order to form microbubbles when said liquid-;gas mixture is expelled from the pipe member via such aperture(s).
Likewise, where the apertures) are of a circular cross-section (ie cylindrical), the diameter of such aperture should preferably be no greater than Ai/C.
Again, it is possible to utilize apertures of maximum dimension (or diameter, as the case may be) less than Ai/C, and still create gas microbubbles of the desired size of 5-100 microns.
Accordingly, a large number of small apertures, where the total combined aperture area Ae acids up to the maximum aperture area [Ai x Di/Do] may be used, in order to introduce microbubb~les in as great a quantity of liquid over a given time. However, having to drill large numbers of small apertures adds to the cost and time in the manufacture of the pipe member and thus of the apparatus of the present invention. It is much less expensive and less time-consuming to drill/mill as few a number of apertures as possible (see discussion below as to what the minimum number of apertures may be for a circular pipe).

The above relationship for the aperture exit area A~ is derived from the surprising observation that the maximum aperture dimension (i.e. the "gap" ) through which the gaslliquid mixture must pass is determined from the experimentally-derived observation that the aperture dimension, hereinafter referred to as the "gap", which best creates microbabhles ofthe desired small size, is S detezmined by the relationship gap "G" = A, I(pipe outer circumfernnce~.
~'or example, for a circular conduitJpipe of minor diatnete:r 1'_7;, outer diartteter DQ, and crass-sectional area Ai= ~rD;z1$ it has been found that for a rectangular aperture cut perpendicularly into the side of the pips, to a depth of %z the pipe diameter, so as ca create an aperture to allow egress of a gasJliquid mixture under pressure: thererhraugh, the maximum pertni$sible "gap" C , ~atnely the maximum vertical height of such horizontal $lot, is:
A,!(pipe outer circmnference) = ~rD,~l(~ a~t~a =p,2l4Do (~:q'rt. #1) The surface exit ;area Ae of two slats each foamed over !a the inner diameter of the pipe D, is calculated as follows:
A~r2xgapx f~~xp, Thus the maxirr~um exit area ,Ae of such apertures for a circular pipe member is thus equal to Ae= 2 x D,2/~Do x %x ~ x D; = 'RDi I4~)m. (1~q'n. # 2) AcGOrdingly, Ae stated more generally iu teru2s of A;,, where Ai = ~i /~ ~Y be stated as follows:
A~ _ '~Di3 = xDi' X ~,lpo= At X DIIDO
dDo 4 Where only one exit aperture is utilized, maxitnurn exit area is = ~rD,~IBDo.
and slated in terms of Ai is equal to Ai x Di1~21~a}
_11_ ~n view of the above, the minimum numher of apertures in a circular pipe tray ire determined. In this regard, ixt a preferred embadimeuut of the apparatus of the present invention, for the reasons discussed above, namely the desire to use the gr~;.atest anxouttt of "throughput"
for the apparatus with the least number of halesJapertures, and thus inxroduce micrabubbIes into the greatest VOIUIII'~.' of llquiCl in the shortest time, the largest-si2:ed aperture utiliza'hIe equals Ail. In order to achieve as much 'Ghroutput of liquid which has xnlcmbubbles introduced therein, the apparatus in a preferred etnbodimertt witl not only possess apertures pf maximum size, but also the combined exit area Ae of such apertures will equal the maxitnutn ~issihle area in order that the apparatus he able to process (ie introduce gas rnicrobubbles) into as much liquid as possible ~cr a given time.
Accordingly, itx the case of cylindrical pipe, having circular (cylindrical) apertures, the minimum number 4f holes(apertutes) which c~x be used is detetm~ined by reference to lrq'n. #2, IS which defines the maximum exit area for a circular pipe member, namely Ae= ~rD;3J4Ta~
Although the surface exit area of a circular hple in a cylindriicai pipe forms a "sa~cidle-like"
exit area on the surFace of the pipe, for small diameter apertures :relative to the diarr~eter of the pipe, the combined surface exit area of all apertures is appmxiuZately equal to the xtumber of apertures tnultiplisd by the exit area Aa~"m of each aperture:
Ae(max)= n x A$P~,,,yt1 x (~ x 1~a214) '~ 5 As discussed, Da is preferably no greater than Ai/C. AccoTdin~;ly , substituting AiIC far Da pr4duces the following:
Ae(max) =n x (n x Da~l~)= n x (~rx [ Ai/C~'' J4 ) ~= n x (~ x ~(x x D:i2 I~)J( ~ x ~0)]2 I4 _l~_ The above equation for A.e(max} cast he equated to l;q~n. # 2 for the Ae(tnaac) of a circular pipe, atld SQIVeCI fOr "n" as ~O~IOW~:
Ae(max} = n x (x x ~(x x DiZ i4}f( ~t x 1?0)]2 l4 ' xD; l4Do n= 16~,a (~q'n.. ~) T3i Accartliztgly, since i=qra, t may, depending on the ratio of Doli~i, produce ~. fractional value for the number of holes "t1", in a preferred embodixuent , the mixiirattm number of circular apertures in a circular pipe merrxber far tnaxitxtum #~olv of lic(uid is defined by the following expression, 1d namely:
a = nearest w3~ole integer to ~x6 x I7~ l D~~ (Eq'n. 6A}.
It is noted that since the maximum comhined aperture exit area Ae for cylindrical pipe i; Ai x DilDo, for apertures cf small diameter D,, relative to the diarr;eter al' the cylindrical pipe, the fouowing is true:
Aen,,",= n x :r Ilx~Mm ~I4 and thus Ai x Dil~lo = rt x ~r D,,~M~.,~a 2l4 The abtwe allows us to solve for the mxxixnum diameter ofthe apertures lrl,"~n""~ , where for circular pipe, Ai = ~i2 follows:

~r x pi2/4 x DiIDO--- ~ n x n x Dr~~~? 2l4 thras ~~.c~,~:W'~Di I(tt x Dog z5 stated alternatively, l~Ac~r.xt ~ ~ x Ai x Dil err x ~ .x Do]

It is usually the case i:or most cylindrical pipe having diameters Di and Do that "n" must be greater than 2 for most pipe, namely there must usually be a plurality of apertures, since otherwise the calculated diarr~eter DA results in a diameter greater than both the interior diameter Di and the exterior diameter Do, which is a physical impossibility, as diameter DA can only be; as large as, or smaller than, Di and Do.
The above value DA(MAX) for a circular pipe having cylindrical apertures may , in instances where there are relatively few number of apertures (ie n is a low number, but greater than one as per the above) give values of DA which are higher than Ai/(outer circumference. of pipe) and which are too high and which will generally not produce microbubbles of desired size (ie less than 50 microns). Accordingly, the two criteria which are preferably satisfied in order to form microbubbles of the .desired size are that Ae(max) = Ai x Di/Do, and Dp(MAx:) _ Ai/(Circumference of Pipe).
For a square conduit of inner dimension D; and outer dimension Do, having inner flow area A; = D;2 and outer circmmference 4 Do, for a horizontally extending slot of Gap "G", it lhas been faund that the maximum gap is likewise the flow area through the pipe Ai divided by the exterior circumference of the (square) pipe, being 4Do. Accordingly, the maximum vertical slot depth "G" for a square pipe rr~ay be stated as follows:
Gap "G"( Max) = A; _ _D;z circumference 4Do The exit area Ae for a plurality apertures in a square pipe may thus be calculated, knowing such maximum G;ap "G". Accordingly, where the apertures comprise a pair of rectangular slots of vertical depth equal to the above Gap (Max), the exit area Ae for the apertures may be calculated as Ae=2xGap(max) x(%ZD;+D;+%2D;) Accordingly, expressed in terms of inlet axea Ai far the sqraare pipe, Ae rnay be stated as follows:
At= 2 x ~ ~ x (2D;) ~ 4~ = lai2 x DL T ~.i x l~i!!ad ~~o ~~o Do Again, where there is only one aperture in such square pipe, Ae is thus:
A~ = Crdp(ri~ax) x (%a ~, ~- h; + tz I~~
and thus, expressed in terns of A.i, is thus t G Ae=Aa x Dil(2xDo) As in the case of circular apernues in circular pipe, where there are circular aper~ues in square pipe, the diazrieter I~R«,xy may be solved for as follows:
Ae=Ai x Di/t~a ti) IS
Ae; n x ~t x 1a, Z !4 (~) where 'n' is the number of aperttues Equating (1) with (2) allows far the diameter D.,~~a to lae salved fir as follows:
20 Ai x Di/pp = tz x ~ x Dd a !4 D"~M"p w~4 x Dial(n xn x Dog - -"~4 x Ai x Di J ~n x~t x 1_3aJ
Again, it is usually the case far most sguare pipe having interior width Di and exterior width lea chat ~n" must be greater than ~ fbr ~xtost pipe, tiaaAely there must usually be a plurality of aperttu~es, sit~ee othe~vise the calculated dianneter DA of the cylindrical aperture results its. a 25 diameter greater than either the interior width Di or the exterior v~radth Do, whieh is a physical impossibility, as diarrieter DA can only be as large as, or smaller than, Di and Do_ Again, the above value I}ALMAX~ fdr a sduare pipe having cylindrical apertures may , in instances where there are relatively Few number of apertures (ie n is a low cumber, but as per the _ig_ above, greater than one) give values of DA which are higher than Ai/(outer circumference of pipe) and which are too high and which will generally not produce microbubbles of desired size (ie less than 50 microns). Accordingly, the two criteria which are preferably satisfied in order to form microbubbles of the desired size are that Ae(max) = Ai x Di/Do, and Dp(M~) -Ai/(Circumference of Pipe).
It has been discovered that the above relationships) hold true for any pipe of symmetrical cross-sectional ;area and having at identical moments of inertia about at least two axis in a plane of cross-section through such pipe.
For example, for a triangular pipe member (of equal interior side length Di and equal exterior side length Do so as to be symmetrical and have identical moments of inertia about at least two axis in a plane of cross-section through such pipe member), the interior cross-sectional area Ai of such pipe member of interior side length Di is:
Ai=,r3 Di2 For two identical horizontal slots (apertures) cut into such pipe to form a "gap" of vertical height "G", where such slots to a depth so as to provide access to one-half of the interior area Ai of such pipe member, the maximum gap (ie vertical depth of each slot) is again determined by the relationship Gap (Max) =Ai/pipe outer circumference= Ai/3Do= _ ,~3 Di2 l2Do The exit area of such two apertures is accordingly determined as the product of the ~;ap multiplied by the perimeter o:f the gap. Accordingly, Ae(max)=2 x gap x (Di + %z Di) =2 x,_r3 Di2 x _3 Di l2Do 2 F.~cpressed. in terms of Ai, ~3 Di3 ~ 1~0 Ae(tnax)= d3 Di2 ac Di = Aa x Di Do Do 'rhe present invention , in a further of its broad aspects, relates to a method for creating microbubbles of gas in a liquid and exposin g them to matter eutrairted in said liquid.
Accordingly, in one broad aspect of the method of the present invention, such method comprises the steps of providing gas to said liquid to form a gaslliqi+id mixture;
directing said ,has-liquid mixture into a hollow pipe member, said pipe meznber having a maximum interior width D, and a maximum exterior width ~~a, said pipe member situate proximate an upper portion of a containment vessel and extending into an ixlterior of said 2D containment vessel, said upper partian of said cantaimnent vessel containing said gas teeing tinder pressure, and a bottom portion of said eontairiment vesseY
substantially containing said liquid;
izt~ecting said gas-liquid mixture under pressure via said pipe member, infra said cc~nt~itW,lellt vessel;
spraying substantially radially outwardly from said pipe member said ,has-liquid mixture into said upper portipn of said containment vessel via at Least rw~ apertures in said pipe member;
said at least two apertures in said pipe member in communication with said gas-liguid mixture in said pipe tuember and having a combined area ~ nixed as a function of a maximum -i7-interior widths D; and maximum outside width Do and a cross-sectional area A;
of said pipe member, wherein Ae is substantially equal to:
A; x D;/Do and removing from said bottom portion of said containment vessel said liquid which lhas been exposed to said microbu.bbles.
In yet another aspect of the method of the present invention, such method comprises a method for converting a liquid-gas mixture having bubbles of gas therein the majority of which are greater than 5-100 microns in size to a liquid-gas mixture having microbubbles of gas therein the majority of which are of a. size between 5-100, comprising the steps o~
directing said gas-liquid mixture having bubbles of gas therein the majority of which are greater than 5-100 microns in size into a hollow, substantially vertical pipe member, having a maximum interior width D; and a maximum exterior width Do ;
spraying said gas-liquid mixture substantially radially outwardly from said pipe member via a plurality of apertures in said pipe member, so that said gas-liquid mixture contacts a vertically extending surface;
said plurality of apertures in said pipe member in communication with said gas-liquid mixture in said pipe member and having a combined area Ae, said apertures sized as a function of said maximum interior width D; and said maximum outside width Do and a cross-sectional area A; of said pipe member, wherein Ae is no greater than, and preferably equal to:
A; x D;/Do collecting a resulting ~;as-liquid mixture having microbubbles of gas entrained therein in a vessel; and removing said gas-liquid mixture from said vassal.
In a Further refinement of the methods of the present invention, oste such method further comprises the step of cohecting within said bottom portion o~E' said vessel said liquid with rtaicrobubbles entrained therein and withdrawing said liquid from said bottom of said vessel at a rate approximately equal to a rate at which said liquid is introdueed into said containment vessel.
In yet a further refinement of the aforesaid methods, the rate of withdrawing the liguid from the bottom of the vessel is substantiadly at a rate which auicrobubbles entrained in said liquid rise in Ehe vessel, sv that at a time when liquid is retnoved frotn said bottom of said vessel said microbubbles will have travelled. upwardly a distance through. said liquid. equal to a depth of liquid in the bottom of the vessel.
In yet a further aspect of the method of the present invention, the liquid-gas mixture sprayed from said pipe member may be passed through a baffle plate member positian.ed irl the containment vessel below said pipe member and interruediate said upper portiozx and said bottom portiost of said caarainment vessel, and the race of injection and removal of has-liquid from the vessel adjusted so that baffle plate xneutber is positioned above xhe level of the iiquid in the ~Q vessel.
In order far the apparatus arid method of the present invention fn form microbubbles, the pressure of the ;has in the upper portion of the vessel (back pressure) need be of a pressure of at least 10 prig to 15 psig, arid preferably at least 2d prig to 30 prig. The initial-gas liqtud mixture, 2S in order to be provided to the apertures and sprayed therefiam, must necessarily, due to a small pressure dxop across the apertures, be supplied at a slightly higher pressure than the pressure of the gas within the upper portion of the vessel (i.e. back pressure), in. prder to be effectively sprayed into the interior of the vessel. The step af'spraying the liquid-gas mixture substantially radially outwardly via the apertures may further in a preferred embodiment be adapted to spray 3a such liquid-gas mixture against the sides of the cantainmer;t vessel.

From another perspective , the invention in a preferred embodiment comprises a method for continuously purifying a liquid containing impuritie$ by exposing the liquid and impurities for a time in a substantially vertically containment vessel to microbut~bles i» tlae range of 5-100 microns in diameter, cotngrising the steps of directing a gas-liquid mixture containing impurities and xEubbles t?f gas the majority of which are in excess of 100 microns in diameter into a hollow pipe member, said pipe member of uniform thickness and having a maximum interior width Di and a maxitxxum exterior width Do and identical moments of inertia an two axis in a plane of crass-section through said pipe means, said pipe means situate proximate an upper portion of said containment vessel and extending vertically dawnwardly in an interior of said contaituneus vessel, said upper portion of said contairunent vessel containing said gas, and being under pressure of at least 10 psig and preferably 15 psig or higher;
1 S injecting said gas-iicluid mixture, under a pressure of at least 5 prig higher than said gas in said containment vessel, into said vessel via said pipe member;
spraying said gas-liquid mixture substantially ltoxizontally outwardly from said pipe meml7er into said upper portion of said containment vessel via a plurality of apertures iri said pipe member so that said gas-liquid mixture contacts interior sides of said vessel;
2o said plurality of apertures in said pipe member an epzmtxunieation with said gas-liquid mixture is said pipe member and having a combined area Aa, said apertures nixed as a function of said ma~tirnum interior width D, and skid maximum outside width Dm and a cross-sectional area A, of said pipe member, wherein A~ is no greater than:
2~ A, x Da/;po collecting scud gas-liquid mixture, now having microbubhles of gas entrained therein the majority of which are now of a size less than 100 microns in diameter, in a bottom portion of said containm~xxt vessel;
removing, from said bat~om portion of said vessel, said liquid with gas miero[aubbles entrained therein at a rate which said micrabubbles enEraiued in said liquid.
rise in said vessel so as to permit said gas microbubbles rime to react with impurities in said liquid; and supplying said liquid-gas mixture to said pige atternber st.ibstantially at a rate at whiel3 said liquid-gas mixture having gas micrabubbles entrained therein is removed from the bottom of said vessel.
I0 Advantageously, the gresexrt ixtvention. in a particular re~neznent of both of one pf the method and apparatus of the present invention, makes use of a sorting phenomenon in order to obtain microbubbles of the desired size.
Specifically, in a particular embodiment where a gas- liquid mixture having gas bubbles of substantially large size ~:-I DU znierons~ entrained therein is sprayed outwardly from a pipe i5 member and captured in a co~tairttrtent vessel, liquid having some: large ~~IOD microns) as well as small (<lOD micronl gas bubt~Ies (but preferably a pxeponderance Qf small gas bubbles) is Collected a said vessel. However, gas bubbles in said liquid which fa-11 vertically down in said vessel when expelled Pram said aperture tend to fall to various depths in said containtttent vessel, before starting to rise in such vessel, depextding on the size o~F the gas bubble entrained in surrounding liquid. Specifically. larger ,gas bubbles within the liquid textd to fall a lesser distance downwardly in liquid collecting at a bottom pariiQn crf the containmentlcolleciis~n vessel than smaller gas buhl~les.
Accordingly, by proper vertical positioning of a liduid-withdrawal tube from the containtnent vr~ssel ibis "sorting" of bubbles within the liquid colle~eting in the bottom portion of the vessel can be taken into account in. obtaining liquid hav~g gas bulalales of the lesser (more dzsirable) smaller diameter. Specifically, gositionirtg of such withdrawal tube on such vessel at a position somewhat above a lowermost portion of said vesset and immediately below a _ z1 _ lowerzn.ost level in said vessel which bubbles of a sire larger than 100 rziicrans initially fall to 'before rising in said vessel, and at a level within said bottom portion af' said vessel which bubbles of a sine less than 100 microns i.nitiaily fall to laefore rising in said vessel, will allow the withdrawal tube to withdraw fratn said vessel only a gas-Iiquicl mixture having smaller (ie <140 micron ) pubblas .
Accordingly, in a preferred method of tine present invention taking advantage of the above "sorting" principle in order to obtain gas microbubbles of a site less than 100 mienatis, such method cau~.prises a method far producing a liquid having gas microbubbles therein the majority of wi~ich are of a size less than 10U microns, comprising ilte steps pf-.
providing gas w said liquid to farm a gasltiquid mixture;
directing said has-litluid mixture into a hollow pipe merttber, said pipe member baying a maximum interior width .D, and a maximum exterior width 1.7w said pipe member situate proximate an upper portion of a cantaiument vessel and extending into an interior of said cantainmeut vessel, said upper portion of said contaituxieni vessel containing said gas being under pressure, arid a bottom portion of said containntiem vessel substantially cantaixung said liquid;
spraying substantially radially outwardly from said pipe member said gas~liquid mixture into said upper pdriion of said contairurient vessel via at least two apertures in said pipe member;
and removing from said bottom pottis~u. c~f said containment vessel, at a position somewhat above a lowermost portion of said vessel, said gas-liquid mixture;
_ ?~ _ ..,.........._ ._.,...,.. , -.:~.~.ipf bp. ~ ~-. . ~.. ..... ".... .._......
,.,",-"."qqm",.s,..~y~ ,..~~5ii~ Wm,w..,«.x.""",".,.__ ..,...._...,........
._...,...._._,~-,.,.~"".,..........."

said position being a position immediately below a loweta~aast level iii said vessel which bubbles of a site larger than 140 rnicrans initially fall to before rising in said vessel, and at a level within said bottarn portion of said vessel which hobbles of a size less than i00 micmns initially fall to beFare rising in said vessel.
In a further ezz~bodirr~ent the invention consists of an apparatus far making use of the "sorting" phenametton.
,Accordingly, in such refinement of the apparatus of the present invention, the 1a containment vessel of the present invention comprises gas-liquid withdrawal means, such withd~wal means in catnmunication with an interior of the vessel proximate a batiQm portion thereat vessel, adapted tA withdraw a gas-liquid mixture having nticrabu6bles of entrained gas therein from said interior of such vessel, such withslr~xwal means situate on said vessel at a paslt~an, said posidan beixag at a level an said vessel below a lau~ermast level within said vessel I 5 which bubbles of a site larger than 100 rriicrans fall tp before rising in liquid in said vessel, and at a level which bula3~les of a size less than lOtl microns fall to before rising in said vessel.
Brief l~escriptiaa of tb~e l~rawirtgs ~0 The following drawings, sltawing selected euibadiments of the invention, are non-limiting and illustratir°e only. ~'or a complete deftnitian. of the sc:oge of the invertrian, reference is to be lead to the sumrrrary of the inver~tian and the claims.
Figure 1 shows a front view c~f arse embodiment of the apparatus of the present inver~tian 25 far creating miczobubbles of gas , said apparatus in the embodiment shown using a cylindrical pipe member and a plurality of harixaataily-extending ayliridrieal apertures;
Figure 2 is an enlarged view of area °°A'' of Figure 1;
_ ~3 figure 3 is an enlarged view of area "B" of Figure', sharwing i~ detail circular apertures farmed ire the pipe member;
Figure 4 is a view of an alternative embodiment of the g~resent invention, similar to that shown in higt.tre l, showing utilization of an inclined but substantially vertical baf#le member;
Figure 5 is ae1 enlarged view of a partiettlar embodiment showing of a pipe member of the present inventiax! of circular cross-section, further showing an embodiment of the pipe member having horizontally-extending rectangular slots formed i:n such pipe tz~ember for acting as apertures to permit the expulsion of a gas-liquid mixture from such pipe member;
Figure SA is a section through the pipe member of Figure 5, taken along plane 3C-~C;
Figure 58 is a section through the pipe member of Figure 5, taken along plane Y-Y;
Figure G is an enlarged view of a particular embodirttent shs~wir~g of a pipe member of the present invention of Square CraSS-SeGtIO~, further showing an embodiment of the pipe member having horizontally-extending rectangular slots fptmed in such pipe member f4T acting as apertures to permit the expulsion of a gas-liquid mixture from sixth pipe member;
Figure ~A is a section through the pipe member of Figure i5, talcen albng plane X-~;
Figure 7 is an enlarged view of a particular embodiment showing of a pipe member of the present invention of triangular gequal sided) cross-section, further showing an etnbadimertt of the pipe member having horizantallywextending rectangular slots formed in such pipe member for acting as apertures to permit the expulsiazi of a ;as-liquid rnixtare from such pipe tztember;
p'igure 7A is a section tluaugh the pipe member of Figure 7, taken along plane X-;
_2q._ Figure $ is an enlarged view of a particular embodiment showing of a pipe meraber of the present invention of rectangular cross-section, further showing an emb~iment of the pipe member having horizontally extending rectangular slots farmed in such pipe tnertxber far acting as apertures to permit the expulsion of a gas-liquid mixture from such pipe member;
Figure 8A is a scetion through the pipe met~ber of Figure 7, taken along plane X-~
Figure 9 is a side view similar to Figure 1. showing another embodiment of the apparatus of the present invention, wherein the apertures far farming the microbubbles axe situate in a plug 1D member which is itself situated at the extreme lowermost distal ezid of the plug meruber;
Figu~ rr 1 A is an cnlar,~ed view of area "A" of Figure 9;
Figure II is yet a further side view similar tp Figure l and 9, showing yet another embodirrsent of tha apparatus of the present invention, in this case having circular apertures situate in the plug rxaember at the extreme ldwermosi end of the pilae member;
Figure ~ 2 is art enlasged view of area "A" of Figure 1 l;
Figure 1~ is an enlarged view of the baffle plate member shown in. Figs. 1,9, and I I;
Figure I4 is a cross-sectional view of a particular embodiment of the apparatus of the present in.ventian which was selected to conduct tests on;
Figure 1S i5 scherrsatic view of additional test apparatus used to test the operability of the apparatus and method of the present invention;
Figure 7.b is a table setting out test data obtained. using the test apparatus of Figure 1~
and 15; and figure 17 is a graph showing a plat of ap~tuue exit aree~ Ae as a fiittction of bubble diameter; such data atstained from data using the test apparatus shown in Figure 14 and IS; and .detailed ~escriptinu s~f the ~.uvetteion Fig, 1 shows arm embodiment of the apparatus 10 of the present invention for producing micrabubbles 12 in a liquid l~.
A means 1~ for introducing gas bubbles 20 into such liquid I~ Hawing in pipe 9 is provided_ Means 1G may ba a verituri , namely a Converging-dive;rgit~g node, as known in the 1~ aft, having at the canvergirtg portiau an alaerture l~ through which gas, typically althou,~;h not always air, is drawn and flows in the form of bubbles 2Q iota the liquid, xo form a gas-liquid mixture 2w. Alternatively, and mare typically, meaxts 1f is simply an orifice to pctrru.t the injection of gas under pressure into said liquid l~ itt pipe member 12, resulting in formation of gas bublsles 2~ within liquid ~.4, which is under a resulting pressure.
2~
The supply 4f gas xnay be from ambient sit, if air is the desired ,gas to be introduced, as shown in .Fig. 1, or alterr~uvely may be Pram a pressuaized tanlk a.f gas {not shown), if sonic other form of gas (such as Hx or Cue) is desired to be iztiroduced.
25 Gas bubbles 2E1 enuained in such gas-liquid mixture 22 in the above mazu~er are typically of a size greater than 1 ~ microns, ar at Ieast a majority of gas bubbles 2Q
entrained in such gas-liquid mixture 22 are a f a size greater than I4Q microns, at typical ambient temperature and pressure (?2° C and I atmosphere).
_?~_ One pf the purposes of the apparatus 10 of the present invention is to reduce the bubble size of the gas bubbles 2~ within the gas-liquid mixture 22 to a sxxe less than 10t? ttucrops, and preferably to a size in The range of 5-Stt microns, in order to increase the ability of the gas in the gas-liquid mixture 22 to react with materials or substances entrained in the gas-liquid mixture 22, S for the purposes of purifying andlor causing certain entrained substances in such liquid 14 to precipitate out of such gas-liquid mixture ~2, thereby ridding such liquid 1~
of such substances.
The gas-liquid mixture 22, having gas bubbles 2fl therein the majority of which are of a site greater than 104 microns, is thereafter conveyed typically by means of a hollow pipe 4r 14 conduit Z4 to an elongate, hallow pipe member 2~, typically although not necessarily, situate within a contaiiune~t vessel 4a, as shown in Fig. 1.
pipe member ~4 contains aperture means cousistiul; of a one or more apertures ~~, extending from an interior ~3 of such pipe member ~4 to an exterior ~7 of pipe member 24 (see 15 enlarged view of one embodiment of pipe meFaber ~4 sbowxt in Fig- 3, wherein pipe member 2~
is cylindrical in cxoss-section, having a plurality of cylindrical apertures therein). Each of apertures 3Z may be of any geometric shape, but preferably are a~f a cylindrical shape as shown in Fig. 3, a cylindrical aperture being the resultant shape that results from drilling of such apernue 32 during manufacture using ~ circular Grill bit, cuilling being one of the easiest means 2~ of forming such apertures 32. teach of said apertuxxes 32 ex#exul horizAntally outwardly and substantially perpendicular to a longitudinal axis of the pipe member 24, Pipe member 2~ is positioned. substantially vattically, as shown in .Fig. 1, and is adapted to receive the liquid-gas raixture 22 and supply same under pressure to aper;ures 32. Each of apertures 32 extend horizontally outwardly from interior 33 of pipe member 24 to exterior 37 of pipe metrtber 24.
2S Pipe member 24 further possesses a plug member ?~, situate at a lowermost distal end thereof far preventing egress of liquid-gas. mixture 2~ &ottr said pipe trternl~r~ 2~i.
As hereinafter explaixted, the sire tbQth width and cmss-sectional area) of such apertures 3? is dependent in a preferred embodiment an certain formulae which are preferably maintained 3Q to allow foTtr~at~C?Fi Of rnicrobul~bles 12 of a desired size, namely less than 100 microns, and p~referahly 5-50 microns, when the gaa-liquid mixture ?2 is expelled under pressure from the pipe member 24 via apertures 32 .
A containment vessel ~0 is further provided. In a prefwed embodiment, containment S vessel. 4Q is an elongate, vertically-extending column, co~gtuvd so as to receive therewithin pipe member 24 in an upper portion 42 thereof. Specifically, ixt the embodiment shown in Fig.
1, containment vessel 4Il is fotxned of a vertical ca»duit ~i~, having threaded flange members 43 affixed din the preferred embodiment by welding for conduits of weldable metallic material and witem such conduits are of a plastic material such as polyvirxyl chloride(PYG), by an 1 ~D adhesive or a batxding agent such chlaroform~ at each a f a bottom and top end X4,45 respectively . Flanges 41,43 are aclapte~l to receive plate members 47,45 at each of skid top and bottom ends 44,45 which may be bolted to flange members 43 respectively by means pf bolts 57, with an intervening gasket i;9, so as to form an enclosed vessel ~~.
15 The purpose of vessel 4D is to receive and contain for a tune liquid lei expelled from sand apertures 32 at a given level "x" within said vessel 40. The resulting micmbubbles 12 produced in the gas-liquid mixture 22 which fall from apertures 22 into vessel 40 may react in the bottom portion 41i of vessel 40 with substances within the liquid 14, so as to cause imgurities to precipitate out. The remaining (purified) liquid 15 may then be removed froth vessel 40 via a 20 lower liquid mihdrawal pipe 5l.
Alternatively, or in addition, the vertical length 5rp of the botxottt portion ~+8 of vessel 4Q
may act as a stratificat#on column and take advantage of a "sorting'°
with respect to gas bubbles.
In this regard, arty remairuxrg gas bubbles lei of a relatively large size (ie in excess of 100 25 microns in size) which uiay still be entrained in said gas-liquid mixture 22 along with smaller gas bubbles after the expulsion of the gas-liquid mixture from apertures 32 wild tend to fall into bottom gorhon ~8 of vessel 4(!. .t~awever, larger gas bubbles tend to fall to or above a level namely above line "X" as shown in Fig. 1) before begintzbxl; to rise in the liquid column contained in the bottom portion of vessel a0 . On the otlser hand, smaller sized gas bubbles tend _2g_ to fall to a level "Z" ar below such level "Z" before hegictning; to rise within such liquid, as shown to Fig. 1.
Accordingly, by positioning withdrawal pipe al at a level below a level "~" to which the majority of larger gas bubbles fall, only liquid 1S subsT~ttially having gas Gobbles of a size less than 100 micmtts may be oGtained when withdrawn from withdrawal tube 5x.
Such liduid 14, having a majority of gas bul~hles therein of a size less Fhan lU0 microns, rosy then he transported vix withdrawal pipe S~ to a further contaixuxtent vessel 52 (not shown] where such gas microbubbles entrained in the liquid 14 may then react (or further react) with substances 1~? within such liquid l~, such as iron bacteria or other undesirable s:ubstaarCes, so as to render such substances harmless sir Cause tltetn Y.o pFecipttate Dut of solution, leaving a purified liquid 15.
Although ii is not necessary 'that vessel 4I! be an enclosed vessel, in the preferred embodiiuent it is desirable that vessel gill he an enclAsed vessel, as shown in Fig, 1. This allows two advantages to be realized.
Firstly, to improve the fonrtation of gas micmbubbles upon the liquid-gas mixture ~~
being expelled from aperture msarts within pipe tnetnber 2~i, the side walls 55 of an enclosed vessel 4A may be used, where the pressure in pipe member ~4 is sufficiently high, as a vertical surface against which resuliiu$ jets SG of gas~Iiduic3 rttay impinge against prior to falling frara upper portion 42 of vessel 4d to bottom portion 48 of vessel 4~" A depictiozt of this preferred embodiment is shown in enlarged view in Fig. 2. 'fhe impaCtio» of the jets Sb of gas liquid agaizlst side walls S~ tends to cause larger gas ?~uGbles entraixted in liguid 14 to break into micrabubbles, thus aiding the formation of gas micrabubbles.
Secondly, the utilixxtiou of an enclosed vessel 40 assists in maintenance of gas microbubbles witl;jn liquid 14 in the hottotn portion 48 of vessel 40, as the vessel 44 may be maintained under a relative pressure. In this regard, in a preferred embodiment, rite internal relative pressure in the upper p4rtion 42 t~f vessel 40 is in the range of ~5 prig or above, with the 3~ pressure of the gas-liquid mixture 22 in pipe ~nemher 24 being in the range of S prig or higl3et than the internal relative pressure within vessel 4t1, to permit the gas-liquid mixture Z2 within such pipe member 24 to be expelled into upper pardon 42 of vessel 4Q via apertures 32. The maintenance of a pressure within vessel 40 less than the supplied pressure within pipe member 2~ assists in formation of gas bubbles in liquid 14. The maintenance of a pressure within such vessel 4(l higher than ambient assists in maintaitiiug babbles of a small sixe within the bottom portion of the vessel 44, which is useful ifthe carting feature desc~bed above is not desired to be used and instead the b4ttotn gartion ref vessel 4t1 is used as a type of coutaixunent vessel to allow reaction of the gas microbuhbles with substances within liquid 14 , as further explained below.
lfl The embodiment of the apparatus and the method of the present invention where the "sorting" of bubbles accardixtg to size is etnplayed and the withdrawal pipe ~i is situated at a level below level "Z" to withdraw only those gas bubbles the majority of which have a size less than 10U microns, is particularly Suited to a continuous as opposed to a batch process.
specifically, because the liquid which is withdrawn from withdrawal pipe Sl is st<bstantially comprised of microbubbles, liquid 14 having such microbubbles entrained therein may he continuously withdrawn from vessel 4A far subsequent pxocessing in a reaction vessel (not shown ) elsewhere.
Where the bottom portion 4$ of vessel ~0 is itself used as s reacCi4rt vessel to allow the txticrobubbles therein to react with substances in such liguid 14, either a "batch" or a "continuous" pmcess may be employed. ~pecificatly, where a batch process is employed, sufficient gas-iidttid mixture ~2 is discharged through apertur~a ~2 to allow the liquid-gas mixture ~2 to rise in vessel 4d to a level "x" approximately one-ltalf to two-thirds the height of vessel 4D. A period of time is allowed to pass, namely the period. of time which it tales for 2S ttticxobubbles of a size leas than 14~ microns to rise from a level at or below level "Z" (see Fig.
3) to level "X". Thereafter the liquid 35 may be withdrawn fronx vessel 44 by withdrawal pipe S1 at a position att such vessel anywhere izttermediate level x and the base of the vessel 4A, and preferably at a level close tp level "Z".
_3p_ Where a continuous process of treatixig liquid 14 is containment vessel aU is desired to be employed, liquid 1~ in the liquid-gas mixture 22 is supplied to the vessel 40 via pipe member ~4 at a rate apprs~xirnaiely equal to a rate at which the liquid iS is withdrawn from vessel 40 via withdrawal pipe 51, In addition, the rate of withdrawal of liquid iS (and the rate of supply of liquid 14) is adjusted so that at a time when liquid is removed fxom said bottosrr porti~aa 4$ of vessel 4A the microbub>xles will have travelled. upwardly a distance tbraugxi liquid 14 substantially equal to a majority of the depth of liquid 14 an said bottom portion of said vessel, namely from approximately level "z" to approximately level "~."_ irl order to facilitate the removal of liquid 15 which has been exposed lo micrabubbles for such period of time, a vertical 1~ baffle plate member bt? may be employed as shown in Fig. 4 to direct the flow of liquid hxvitig micrabubbles eutFairsed therein as shown in Fig. 4. In such embodiment withdrawal tube Sl is preferably situate close to, but below level "7C", and withdraws liquid 15 which has beers expciaed to gas microbubbles for the time that it takes such tnicrobubbles afrer havixag fallen from level "x" to level "z" on a first side 70 of such baffle member 60 to rise on the other side 71 of baffle 1~ member 40 .frorri level "Z" to level "X".
In a further embodiment, the apparatus 1U 4f the present invention further includes a horizontal laaffle plate member ~0 iref Fig. 1 and Fig. 4), positioned intermediate upper portion 42 and bottom portion 4f of vessel 40, arid above level "x" of liquid I4 in the vessel 44, so that 24 gas-liquid mixture sprayed from pipe member 2~+ is permitted to pass throug3x such baffle member 8fJ when falling to bottom portion 48 of vessel 4t1. $able plate member go is provided with a series of orifices ~2 (see Fig. 13 showing enlarged view of hari2antal baf#le member 8(1) to permit ,has-liquid mixture 22 to further fall to bottotu pot3ian 48 of vessel 44. F3aftie plate mertiber 8t1 further assists in converting gas hu6bles ~0 in gas-liquid miacture 22 to tnicrobubbles.
Pipe member 24 hawing orre or more apertures 32 thereon may he any ho~Iaw elongate tubular member, substantially sytt~rnetric$1 in cross-sectiati. Figures 5, fi, 7, and 8 show tbtu separate embodiments, where such pipe member 24 is alternatively c~f, but not limited to, having a circular, square, triangular, and xectangular cross-sectional area respectively .1n vrc3er for the apertures to best form mi~ct~bubbles, in a prefexxed embodiment a specific mathetuatical relationship exists between the interior area of the pipe member ~4, and the combined exit area Ae of apertures ~~, where such pipe member 24 has a maximum exterior width Des and maximurrc interior width Vii. Such relationship between the combined exit area Ae of the apertures ~2 and the inlet area Ai of the gipe member 24 is essentially a functipn of the thickness of the pipe member {namely the ratio of 1~i to Do) , and is ~.
cie~nite relationship for symmetrical pipe members 24 of unifatut wall thickness.
Specifically, it has been found experimentally (see examples 1 and ?, below) axed confumed by derivatis~n (see summary of invention, above) that for pipe metxtbers 24 of uniform wall thiclmess and having a ma.xiuit)m interior width Di and a ttzaximutn exterior width Do, where the pipe member 24 has identical moments of inertia about at least two separate axis in a plane of cross-section through such pipe tner#tber ~4, that for formation of tnicrobubbles of gas in a liquid 14 (ie bubbles of less than 104 micrntts) under conditions of standard temperaxure and pressure, Ae can he less than or edual to, but no greater than Ai x I~iIDo where there exist a plurality of apertures 32 in pipe member 2$. Where only one aperture 32 exists in pipe member ~4, such aperture may only have a cross-sectional area no greater than Ai x DiI2Do.
Figure 5 shows ~ detail view of a pipe member 24 of the present itmentioal, having a cixeular arose-section, of maximum x~z~ernal width Di, and maximum exterior width Do, and internal area Ai= ~c x Di ~ 1~.. Figure 5 also shows the confiSura#ion of pipe member 2~ and apertures ~2 used to deterntine the relationship between inlet arcs Ai and combined aperture exit area Ae. Two rectangular slots 90 were formed in pipe member 24, on apposite sides thereof, each to a depth of ~~z ~o. 8ach rectangular slot 9p forms an exit wee equal to r~gapr~ x ~ x pi (see ?5 Fig. 5f3) , so as, in the case of two rectangular slots 94, to form a combined exit area Ae= 2 x rr,7apn x '1r ~ f-rl It was experimentally found tree example 1, below) that the maximum combined exit area far at least two err more apertures was Ae can be no greater tYian Ai x DiIDo where babbles of a sine less than 1(10 microns are desired.

~aviug a raaximum combined exit axes Ae means that the aperture "gap" shown in Figure 5 will be a maximum. Accordingly, whzre maximum throughput of gas-liquid mixture 22 is required through apparatus 10 of the present mventi~azt, the maximum combined aperture exit area Ae is used. Where Ae ~Ai x lSi/Do, setting this equal to 2 x ;;ap x n x Ai and salving for the gap, this means the "gap" can only be ~Ai x L?ilpQJl2 x ~ x Iii which stated more simply is equal to Ailn x Do., where 7t x lrlo is the outer circumference of pipe member ~4.
Accordingly, in a further embodiment, a further restriction exist on the width of the 14 ''gap" shøwn in Fig. .~, namely that the "gap" be no greater than the quotient of Ai and the outer circumference of pipe member 34, namely n x lots. Stated ~ other terms, to form bubbles in the extruded jets S6 of gas..liquid mixture 22 urhich is expelled Exam rectangular slots 90 camgris~rig apertures 32, such apertures 32 raay only be of a txcaximum vertical depth ("g.ap") of .AiIC, finely ~ 1t x Di a I4 JI ~ ~ x poJ (ie I1i 214 .Do ). Thus where the maximum aperture distance (ie 1S the maximum "gap") of l~i Z !4 Do is used, so as to be required to drill the fewest slots or apertures 3~, the maximum "gap" of aperture is typically used, na~n.ely Ai~circum~'erence o f pipe member 24, which for a cylindrical pipe member 24 is simply Di z !4 'po.
As may be seen froxri Figure 5, pipe member 24 possesses unifarEn wall thiclmess (ie Do 20 less lei is always a cbnstant). Moreover, as may be seen from Fig. 5A, such pipe mexttber 24 possesses ax least two identical morr~enls of inertia in a plane of cross-section, namely the moments of inertia about axis xt and Iz are identical, namely n16~ [Dog - lai ~
The same relationship applies in the case of pipe memba;r 2~ of square crass-sectional 25 area Ai, as shown in Figs b and 5A, of uniform iluc~ess "t". Tlt.us for two rectangular slots qa within square pipe member 24, as may be seen Pram Fig. GA, ~e corrtbined aperture exit area Ae may be calculated as Z x "gap" x. ~I12 Di -r ~1i t l~ ,pi ]. ~Nhere the maxitnutn "gap" is detexmitted by the surprisingly- found relationship of Ai!(circuxaference of pipe), namely Ail4 f.?a , then A.e thus becomes 2 x Ai/4Do x [ 2Ai~= Ai x Bili~a. Again, a square pipe metnher 24 _. . ~__._.. _ _,. " ~~~,.n~,~~,~~, ~._ .. ..._ .__ _ .

has identical moments of inertia abQUt two identical axis I1 and Ia; in a plate of crass-section, namely It = Iz = [Dap - Di° ~Il~
The same relationship applies in the case pf pipe member ~4 of triangular (equal sided) S cross-sectional area Ai, as may be seen from. Fig. 7 and 7A. ~'hus for rwo rectan~xlar slots 90 within equilateral triangular pipe member 2~i of depth equal to f2 Do on one side as shown in Fig. 7A, as may be seen from Fig. ~A, the cotubined aperture exit area znay be calculated as 2 x "gap" x ~11~ Di t Did. Where the maximum "gap" is detertnixted b;y the surprising relationship of AiIC, which en the case of an equilateral triangle of interior maximum width Di equals Ail3lao, then Ae= 2 x gap x 3!2 l:~i= 2 x Ail3Do x 3/? Dl , which reduces again to Ae=Ai x Dil~o. Again, as may be seen from Figure 7A, an equilateral sided txiat~gulax' pipe member 24 has identical moments of inertia about two axis h and Iz in a plane of crass-section, rtapnely It = Iz .
t5 For a symmetrical pipe member 24 which does oat have identical morrtents of inertia about two axis irt a plane of cross-section, such as a rectangular pipe member 24 as spawn itt Fig.
8 and 8A (namely h ~I2 ~. the derived relationship of Ae=Ai x DiIDo does not apply.
T~owever, in the case of a rectangular pipe rrtember ::~ having maximum exterior dimension 15t , rrtinimum exterior dimension Da , maximum interior dimension D~ , and mittitxtum interior diFrtension D~ , as shown in Fi,g_ 8 and 8A, the combined exit area Ae for 'two rectangular slots 90 as seen in .Fig. 8A is determined as 2 x "gap" x [ %'~
?~4-r D3 -r %z D4 ~. Agaixt, using the surprising result that the maximum " gap" equals AiIC, namely Ail[2x (Dz+ .D,)~, then Ac = 2 x gap x [p3+ Da ] = Ai x [D~t D3 ~! [D2+ ~1t ~-With respect to the location of the apertures 32 of the present invention, from which gas-liquid anixture 23 is expelled, aperGttres 32 may be formed wirllin pipe member 24, as shown in Fig. 1 attd particularly in enl$rged view shown in Figs. 3 and Figs. 4 throw 8 inclusive.
Alternatively, apertures 32 rnay be formed in plug member 2~.. Fig. 9, and Fig. 10 showing 3~3 enlarged detail, illustrate formation of a pair of rectangular slots 9f1 which serve as apertures 32 -~4-in plug means 25. Fig. 11, and Fig. 12 shaving enlarged detail , :illustrate the ~employrrtent of a pluralixy of cylindrical apcrlures 32 in plug txtember 2S. 4f course, as in Tlre case where the apertures 32 are situate within the pipe >:aember 24 itself, such apertures may he of any geometrical cross-sectional area, wish circular cross-sectional area being preferred due to the S ease in creating cylindrical apemtres 32 having circular cross-sectional area, ouch as by drilling with circular drill bits.
~x~r~tpte 1 A series of seventeen various-sited apparatus 14 were can5trueted in accordance with one of the embodiments o f the invention as contemplated ?tereirt, namely that etnbadiment shown in Fig, I, having a pair of apertures 3z in the form of horizontally attending recta~agular slots 90, as shown in Fig. ~.
l3ach of the aforesaid seventeen test units comprised a shell (referrs~d to above and below as a vessel 40~, having itt an upper portion 42 thereof a downwardly extending, substantially ve~ical cylindrical pipe tnernber 2~ s~f various Di and Do, ranging from nominal pipe nominal diameters of O.St? inches ur I~.O inches.
Each of pipe members 24 for the various fast units had a ps~ir of rectatagular pppased 2Q slots 90 therein, as shawu. in Fig. S. xhe exit area Ae for the pair of slots was set as the ma~:imam., in accordance with the requirement Ae {maxi = Ai x Dillao. »ecause the width of each of the slats 9I1 was the width Di of rah pipe member 24 as shown in Fig.
5, the vertical dePTh tie "gap") of each of the slats 9Q was accordingly thereby pry.-detertatined dire to the requirement that A~A.i x DiIDo, and was gap~~,~",a= Ai!{ou;er circumference of pipe member Z4).
Vessels 4p of var;ous notxrinal diameter sizes were used arid matched. with correspondi>xg pipe members 24, with the vessel 4A having a nominal diameter of approximately six times the pipe lnenzber 24 nnminlal diameter . This resulted in a thatching of vessels 4Q with pipe nzenlbers _3g_ 24, wherein the vessel 40 nominal diameter ranged from a nominal 3.0 inch diameter to a 10.0 inch nominal diameter.
Various lengths of vessel 40 were used, ranging from 34.2 inches for a vessel/shell 40 of 3.0 inch nominal diameter, to 260 inches for a vessel 40 of 10.0 inch nominal diameter.
Various lengths of pipe member 24 were used, ranging from approximately 7.30 inches for a pipe member 24 of 3.0 inches nominal diameter, to 12.0 inches for all pipe member diameters of approximately 1.0 inches nominal diameter and greater.
Water at 15° C and air at 21°C was used as the liquid and gas, respectively. Water, having bubbles of air of a sizf; greater than 100 microns therein the majority of which were of a range of size between about 100~.m to 3mm, and under a pressure slightly exceeding 20 psig, was provided to pipe member 24, and sprayed into an upper portion of vessel 40 via rectangul~~r slots 90, such upper portion of the vessel containing gas, under a pressure of approximately 20 psig, which uses slightly less than the supplied pressure due to the pressure drop across the aperture(s), and a lower portion of said vessel containing water having microbubbles therein.
Four inlet flow rates of water were used, namely 6ft/sec, 7 ft./sec, 8 ft./sec., and 9 ft./sec into the vessel 40 via pipe member 24. A lower withdrawal pipe was used to withdraw water having microbubbles entrained therein from vessel 40, which was then provided in a holding tank (not shown) at ambient atmospheric pressure.
In all seventeen instances for the devices tested, microbubbles were formed in vessel 40 over each of the four volumetric flow rates, of dimensions less than 100 microns.

Example 2 Purpose The purpose of this experiment was to confirm various formula for optimum creation of microbubbles using the apparati of the present invention.
This was done by evaluating the effect of aperture size and apertures exit area on the size of the bubbles produced.
~pa~atus Apparatus of the type shown in Fig. 14 was selected, and in particular an apparatus of Fig. 14 having the dimensions for inlet pipe member OD and ID and (upper) impaction pipe length, as well as shell (vessel) height and diameter.
Figure 15 shows associated equipment used with the selected model of apparatus 10 of the present invention in conducting the above tests. A Plexiglas receiving tank 100 was utilized for receiving water having microbubbles entrained therein from apparatus 10 and to permit observation of bubble rise to permit calculation of bubble velocity (used to determine bubble size). A ruler 102 was attached to the outside of the tank to allow form measuring distance travelled by bubbles per a given time interval, to calculate (in the manner described below) the bubble size. A separate tank 104 was provided as a reservoir to permit supply of water to pump 10b. Additional piping 10$ pernaittecl supply , via a globe valve 1.10 and venturi nozzle 11~ to pipe member 2~ of apparatus 10. Water exiting vessel ~p of apparatus 1 Q
passed through a flow meter 115 and pressure gauge 117, and then through a globe valve :t 18 to Plexiglas tank 100.
Procedure pipe mexrtbers 2~ ware created, haul g horizar~tall~e~tending cylindrical apertures ~2, of diameter, number, and comlained exit area Ae as recorded in Fi~,~re 1G.
l0 Each coc~ribination of bole (aperture) size and exit area was tested with the same standard procedure set out below. Each test was run under the same caxu3itians of back.
pressuFS (i.e.
pressure of gas is the upper portion of vessel ~0, narxtely appro~ciirtately 20 psi), Flow rate, water volume, water temperature, and pressttxe dz~ap across the Venturi nozzhe. The same apparatus 10 was used for all the tests, and pipe iuemher 2a was chaxrged between rues.
lvleasurir~g the rise of the bubbles against time permitted determina.tian the size of the average bubble in the tank.
~ The apparatus 10 was connected to the Plexiglas pump x.00 and pump X06.;
~ Valve 1 i8 from tanl:100 was opened tn allow equilibrium level between tanla and vessel 4A of apparatus 10;
~ Pump lOG was started and allowed to run until constant level was achieved in vessel ~40 of apparatus d0 ;
~ Valve 130 couttnlling claw through venturi nnz2le 1I2 was adjusted to create a 20 psi drop across the nozzle X12 ;
~ The back press~ire ozy vessel 40, namely the pressure of the gas itt upper portion of vessel 40, was then adjusted to 20 psi;
~ The apparatt 10 and test equipment was lei to trot for 3.~ minutes;
~ Pump lilt was turned o#fand valve 118 between vessel 44 and tank 1i10 was closed;
_~g_ ~ Once a clear view at the bottom to the rear of the tank 11?~ was established huhble rise was monitored and recorded at the given time intervals;
~ Once tank ~fHa became clear ofbubbles the tap ofves:~el 4I! was removed and pipe member 24 was changed t4 a pipe member having differing cumber and for diameter pf apertures;
The above procedure was xepeated far pipe members 34 having agertures 32 of various rzeunber andlar diameter, to determine the effect of area and hale size ors the vessel's perforrtiatice.
1~ 'I've results afthe measurements, and. resulting calc~latiaus, are compiled in Table I6.
C~lculatian~
The design uses the formula Egu.1 _ ~ x~7~, ~
~''' 4 where: A;=ix~.let area 1~, = inside diameter afpipe This forxxl~a defines the inlet area of pipe on the vessel 40. The inlet area Ai is used. to determine the gap size or tnaxixnutu hale dimension.
Eclu.~
Gap_~ ~''oo where: Gap = hale dimension or Gap size Al= izilet area ~5 ~p = outside diameter of pipe;
This formula defines the maximum length of one afthe holes°
damertsians. The maximum combined aperture exit area Ae is determined usixig the pipes°
dimensions in the following formula Eqa.3 x. ~ pi 3 A a = pi ~ n x Gad a W114Ie: Aa'~1"laXil'riltlxl exit area Di ~ i.x~side diameter of pipe Do = outside diameter of pipe This formula defines the zrzaxi~lum area: that will produce the desired micrabubbles. bait areas less than this value are capable of pro~.ucing the micrabubbles whereas any area greater than this does nQt produce bubbles t#tat are cuff ciexttly small. Both the hole site arid exit area are parameters that effect ibe size of the bubbles that are produced by the vessei_ la Using Stokes 1'raw the si2.e of the bubbles produced is determined by the iise velocity of tl:cese bubbles. Stones Law states Eqn.4 3 tRa -1~ ~.~N
whew: v = velocity of bubble rise g = gravitational cqnstaxit Fw~ pa ~ deilsily Qf wafer and air ~, = viscosity of fluid 2Q )~ _ diameter ef has bubble i~z fluid each of the experimental rues produced data which appear iri Figure 16. >rach experimental run is also accompanied by a corresppudirig hole diaxrteter, cumber ofholes acccl 25 exlt area.
Tirrie and distance traveled were used to calculate the rise velocity.
.Eqii.S
- ~a -where D = diameter (cm) v = velocity (cm/s) ~, = viscosity of water (Poise) = 0.0112 P
g = gravitational constant = 981 cm/s2 pW = density of water = 0.99913 g/cm3 @ 15°C
pa = density of air = 1.239 mg/cm3 @ 15°C
The number of holes, the hole diameter and the resulting exit area were determined using the following equation.
Eqn.7 Ae= NH'' DA24 where: A.e = exit area NH = number of holes DA = hole diameter Sample Calculations The first calculation needed was to determine the maximum exit area D; = 0. 824 Do =1. 05 Ae= '~xD' 3 4 x Da ~ = 0 . 418487 in2 The following calculations are those used to determine the exit area at a given hole size and number.
NH=21; Dia=532 ~~ P~=NHXD,~2 X 7f 1~=0.4026inZ

D;= 0.824 Do=1..05 ~_ ~xD~3 4 x Do ~ - 0 . 4184 8 7 in2 The following calculations are those used to determine the exit area at a given hole size;
and number.
NH= 21; Dia=532 ,~ ~- ~xDA2 X 7~

P~=0 . 4026 in2 The following are a set of sample calculations for one interval. The calculations find the rise velocity of the bubbles and their corresponding diameters.
d2=4; dl=3; tl=5~ tZ=lOt v= ~
to - t1 v-_ 0.2~m~s D= 0.00202948 can Results Results of the above tests are found in Figure 16. Fig. 16 lists the drill sizes used for creating the apertures, the number of holes(apertures), and the corresponding combined exit area Ae for each pipe member (nozzle) 24, as well as the resulting bubble size.
As may be seen from Fig. 16, where the combined exit area Ae of the apertures exceeded the pre-determined exit area of Ai x Di/Do, namely exceeded 0.418487 inz , the bubble size was greater than 50 microns. (ref. those tests where bubble diameter was 68.26, 53.2, 68.45, 53.6, 58.71, 65.60 and 82.44~n respectively).

As may also be seen froze Figure 1 f>, where the aperture dia~Erteter was :'eater than Ail(auter circumference of pipe member ZA), namely greater than 0. Z 61 inches, the average bubble size was ~reateF t#~ 50 tnicrans.
Where the combined aperture exit area Ae was less than or approxiu~ately equal to Ai x lail:Da, namely less than or equal w x.41$487 in'' and the aperture diameter less than or equal to Ail(auter circumference of pipe merriber 24), bubble site was less than 5~
microns.
Figure 1'7 is a graph prepared &ortt that illustrates a relationship between combined exit area Ae and bubble diameter. The average diameter front the first ~0 seconds (in most cases) was platted agains; the exit area. Figure 17 demo~stra~tes a def ned relationship betureen ttxe rwo variables that occurs while the hale diaxne#er is held constar#t. '1'his ,gives evidence of'the ia#luence of exit area an bubble size. The larger the exit area the larger the siie of the bubbles prr~c#wGed.

Figure 17 has an area that is below and to the right of the doted line. such represents a design co~guratian afthe apparatus 1d of the present invention which produces micrnbubbl$s in the desired range al less than SQ microns.

:~
Although the disclosure describes and illustrates selected emlsodiments of the invention, it is to be understQad that the iitve~tian 1s Rt~t limited to these pat~ieular selected embodiments.
2S Many variations and modiftcatiQns will now occttx to those skilled in the art . Far a complete definition of the scope of the invetttian, reference is tp further be had to the summary of the invention and in particular the appended claims.
- ~3 -

Claims (61)

1. An apparatus for reducing the size of gas bubbles entrained in a liquid-gas mixture from a first size to a second smaller size, said apparatus comprising:

elongate, hollow pipe means, substantially symmetrical in cross-section of interior cross-sectional area Ai, positioned substantially vertically, adapted to receive said liquid-gas mixture having said bubbles of said first size entrained therein and supply said liquid-gas mixture under a first pressure to aperture means, said pipe means having plug means situate at a lowermost distal end thereof for preventing egress of liquid vertically downward from said distal end;

said aperture means situate on said pipe means and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means and extending from an interior of said pipe means to an exterior of said pipe means, each adapted to expel said liquid-gas mixture substantially horizontally outwardly from said pipe means via said aperture means so as to thereby reduce the size of said bubbles in said liquid-gas mixture to said second smaller size; and a containment vessel, an interior upper portion thereof adapted to contain quantities of said gas at a second pressure greater than an ambient pressure, a lower portion thereof adapted to capture said liquid-gas mixture having bubbles of gas entrained therein of said second smaller size after being expelled from said aperture means;

said pipe means of uniform wall thickness and having a maximum interior width D i and a maximum exterior width D o , having identical moments of inertia about at least two separate axis in a cross-sectional plane through said pipe means;

said aperture means comprising a plurality of apertures having a combined cross-sectional exit area A e; and said combined aperture exit area A e of said plurality of apertures defined as a function of widths D i and D o and said cross-sectional area A i of said pipe means, wherein A e is no greater than:

A i × D i/D o and where the individual cross-sectional area of each aperature is no greater than A i × D i/2D o.

2. An apparatus for reducing the size of gas bubbles entrained in a liquid-gas mixture from a first size to a second smaller size, said apparatus comprising:

elongate, hollow pipe means, substantially symmetrical in cross-section of interior cross-sectional area A i, positioned substantially vertically, adapted to receive said liquid-gas mixture having said bubbles of said first size entrained therein and supply said liquid-gas mixture under a first pressure to aperture means, said pipe means having plug means situate at a lowermost distal end thereof for preventing egress of liquid vertically downward from said distal end;

said aperture means situate on said pipe means and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means and extending from an interior of said pipe means to an exterior of said pipe means, each adapted to expel said liquid-gas mixture substantially horizontally outwardly from said pipe means via said aperture means so as to thereby reduce the size of said bubbles in said liquid-gas mixture to said second smaller size; and a containment vessel, an interior upper portion thereof adapted to contain quantities of said gas at a second pressure greater than an ambient pressure, a lower portion thereof adapted to capture said liquid-gas mixture having bubbles of gas entrained therein of said second smaller size after being expelled from said aperture means;

said aperture means comprising a single aperture having a cross-sectional exit area A e;
and said exit area A e of said aperture defined as a function of widths D i and D
o and said cross-sectional area A i of said pipe means, wherein A e is no greater than Ai × D i/2D o

3. The apparatus as claimed in claim 1 or 2 , wherein said second pressure is as least 10 psi greater than said ambient pressure, and said first bubble size is a bubble size where the majority of bubbles are of a range between 100 microns and 3 mm.

4. The apparatus as claimed in claim 1, 2 or 3, further having substantially vertical surface means adapted to be impacted by said liquid-gas mixture when expelled horizontally outwardly from said pipe means via said aperture means.

5. An apparatus for providing bubbles of gas in a liquid, comprising:

a vessel adapted to be positioned substantially vertically and adapted to contain a volume of gas under a second pressure exceeding ambient by at least 10 psi, in an upper portion thereof;

means for introducing gas bubbles into a liquid to form a liquid-gas mixture having gas bubbles entrained therein under a first pressure exceeding ambient;

elongate, hollow pipe means within said vessel, of interior cross-sectional area A i, for conveying said liquid-gas mixture under said first pressure greater than said second pressure to an interior of said vessel, substantially symmetrical in cross-section, situate centrally in said vessel and proximate said upper portion of said vessel and extending substantially vertically downwardly within said vessel from said upper portion thereof, and having plug means situate at a lowermost distal end thereof for preventing egress of liquid vertically downward from said distal end; and at least two apertures means situate on said pipe means and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means extending from an interior of said pipe means to an exterior of said pipe means, each adapted to permit expulsion of said liquid-gas mixture under pressure substantially horizontally outwardly from said pipe means directly into said interior of said vessel in an expelled gas-liquid stream having gas bubbles entrained therein.

6. The apparatus as claimed in claim 5 for separating out gas bubbles from said expelled gas-liquid stream of a desired size, wherein said vessel is adapted to collect and contain within a bottom portion thereof said expelled gas -liquid stream as a collected volume, said collected volume having gas bubbles therein of a range of sizes;

further comprising gas-liquid withdrawal means to withdraw said collected volume from said bottom portion of said vessel;

said withdrawal means in communication with said bottom portion of said vessel and situate on said vessel at a vertical position thereon;

said vertical position being at a level on said bottom portion of said vessel below a lowermost level within said vessel which bubbles of a diameter larger than a desired size fall to within said vessel before rising in said vessel, and at a level which bubbles of a desired size fall to before rising in said vessel.

7. An apparatus for creating bubbles of gas in a liquid the majority of which are of a size less than 100 microns, comprising:

means for introducing gas bubbles the majority of which are of a size between microns and 3 mm into said liquid to form a liquid-gas mixture;

a vessel adapted to be positioned substantially vertically and adapted to contain a volume of gas in an upper portion thereof under a second pressure exceeding ambient by at least psi;

elongate, hollow pipe means for providing said liquid to an interior of said vessel, having a longitudinal axis and substantially symmetrical in cross-section so as to have identical moments of inertia about at least two separate axis in a cross-sectional plane through said pipe means, of uniform wall thickness, and having a maximum interior width D i and a maximum exterior width D o and an interior cross-sectional area A i, said pipe means situate substantially centrally in said vessel and proximate said upper portion of said vessel and extending substantially vertically downwardly within said vessel, adapted for supplying a liquid under a first pressure greater than said second pressure to an interior of said vessel, and having plug means situate at a distal end thereof for preventing egress of liquid vertically downward from said distal end;

at least two aperture means situate in said pipe means and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means, each extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said liquid substantially horizontally outwardly from said pipe means, of combined cross-sectional exit area A e; and said combined aperture exit area A e of said aperture means defined as a function of widths D i and D o and said cross-sectional area A i of said pipe means, wherein A e is no greater than:

Ai × D i/D o

8. The apparatus as claimed in claim 7, wherein A e is substantially equal to:

Ai × D i/D o

9. The apparatus as claimed in one of claims 1-8, said aperture means each having a maximum vertical dimension G, said pipe means having an exterior circumference C, wherein G is no greater than A i / C.

10. The apparatus as claimed in one of claims 1, 3, 4, 5, 6, 7, 8, or 9 wherein said aperture means comprise substantially cylindrical apertures.

11. The apparatus as claimed in one of claims 1, 3, 4, 5, 6, 7, 8, or 9 wherein said pipe means has an exterior circumference C, and wherein said aperture means comprise cylindrical apertures each of diameter D A , where D A is less than A i / C.

12. The apparatus as claimed in claim 1, 3, 4, 5, 6, 7, 8, or 9 wherein said pipe means has an exterior circumference C, and wherein said aperture means comprise cylindrical apertures each of diameter D A, where D A is substantially equal to A i / C.

13. The apparatus as claimed in claim 1, 2, or 3, wherein said aperture means comprise one or more horizontally-extending slots in said pipe means.

14. The apparatus as claimed in claim 1, 3, 5, 6, 7, or 8 , said pipe means having an exterior circumference C, wherein said aperture means comprise a plurality of horizontally-extending rectangular slots in said pipe means, each of a horizontal width no greater than said maximum interior width D i of said pipe means, and each of a vertical depth no greater than A i / C.

15. The apparatus as claimed in claim 1, 3, 5, 6, 7, or 8 , said pipe means having an exterior circumference C, wherein said aperture means comprise a plurality of horizontally-extending rectangular slots in said pipe means, each of a horizontal width substantially equal to said maximum interior width D i of said pipe means, and of a vertical depth substantially equal to A i / C.

16. The apparatus as claimed in claim 1, 2, or 3, wherein said aperture means comprise one or more vertically-extending slots in said pipe means.

17. The apparatus as claimed in claim 1, 3, 5, 6, 7, or 8, said pipe means having an exterior circumference C, wherein said aperture means comprise a plurality of vertically-extending slots in said pipe means, wherein said slots are of a width no greater than A i/C.

18. The apparatus as claimed in claim 1, 3, 5, 6, 7, or 8, wherein said aperture means comprise a pair of vertically-extending slots in said pipe means, disposed on substantially mutually-opposite sides of said pipe means, said pipe means having an exterior circumference C, wherein said slots are of a width no greater than A i/C.

19. The apparatus as claimed in claim 7 wherein said pipe means comprises a substantially cylindrical pipe member having an exterior circumference C, said maximum interior width D i equal to an inner diameter of said pipe member, and said maximum exterior width D o equal to an outer diameter of said pipe member.

20. The apparatus as claimed in claim 19, wherein said aperture means comprise substantially cylindrical apertures.

21. The apparatus as claimed in claim 19, wherein said aperture means comprise substantially cylindrical apertures, each having a diameter D A, where D A is no greater than A i / C.

22. The apparatus as claimed in claim 21, where D A is substantially equal to A i / C.

23. The apparatus as claimed in claim 19 , wherein said aperture means comprises horizontally-extending slots in said pipe member.

24. The apparatus as claimed in claim 19, wherein said aperture means comprises horizontally-extending rectangular slots in said pipe member, each of a vertical depth equal to or less than A i / C.

25. The apparatus as claimed in claim 24, wherein said horizontally-extending slots each extend to a depth within said pipe member substantially equal to 1/2 D o , and are of a horizontal width substantially equal to D o.

26. The apparatus as claimed in claim 19 wherein said aperture means comprises vertically-extending slots in said pipe member.

27. The apparatus as claimed in claim 19, wherein said aperture means comprises vertically-extending slots in said pipe member, each extending vertically along said pipe member a distance no greater than A i / C .

28. The apparatus as claimed in claim 19, wherein said aperture meass comprises vertically-extending rectangular slots in said pipe member, each of a width substantially equal or less than A i/C.

29. The apparatus as claimed in claim 7, wherein said pipe means comprises a substantially square pipe member of substantially square exterior and interior dimensions, having an exterior circumference C, said maximum interior width D i equal to a length of an inner side width of said square pipe member, and said maximum exterior width D o equal to a length of an outer side width of said square pipe member.

30. The apparatus as claimed in claim 29, wherein said aperture means comprise cylindrical apertures.

31. The apparatus as claimed in claim 29, wherein said aperture means comprise cylindrical apertures, each having a diameter no greater than A i / C.

32. The apparatus as claimed in claim 29, wherein said aperture means comprise cylindrical apertures each of diameter substantially equal to A i / C.

33. The apparatus as claimed in claim 29, wherein said aperture means comprise at least a pair of horizontally-extending slots in said pipe member.

34. The apparatus as claimed in claim 29, wherein said aperture means comprises horizontally-extending rectangular slots in said pipe member, each of a width substantially equal to said maximum interior width D i of said pipe member, and each of a vertical depth equal to or less than A i / C.

35. The apparatus as claimed in claim 29, wherein said aperture means comprises at least a pair of vertically-extending slots in said pipe member.

36. The apparatus as claimed in claim 29, wherein said aperture means comprise vertically-extending slots in said pipe member, each of a width substantially equal or less than A i / C.

37. The apparatus as claimed in claim 29, wherein said aperture means comprise vertically-extending rectangular slots in said pipe member, each of a vertical length substantially equal to said maximum interior width D i.

38. The apparatus as claimed in claim 1, 5, or 6 wherein said aperture means are situate in said plug means.

39. The apparatus as claimed in claim 21 wherein said aperture means comprise a plurality 'n' number of circular apertures of diameter Da, wherein n is substantially equal to:

A e /(.eta.× Da2/4)

40. The apparatus as claimed in claim 22 wherein said apertures comprise a plurality n number of circular apertures, wherein n is function of Di and Do, wherein n = nearest whole integer to [16 × D o / D i]

41. An apparatus for reducing the size of gas bubbles entrained in a liquid-gas mixture from a first size to a second smaller size, said apparatus comprising:

a containment vessel adapted to be positioned vertically and adapted to contain a volume of gas in an upper portion thereof under a second pressure exceeding ambient by at least 10 psi;

elongate, hollow pipe means for providing said liquid-gas mixture to an interior of said vessel, having a longitudinal axis and of uniform wall thickness and having an interior cross-sectional area A i, said pipe means situate substantially centrally in said containment vessel and proximate said upper portion of said containment vessel and extending substantially vertically downwardly within said vessel, adapted for supplying said liquid-gas mixture under a first pressure greater than said second pressure to an interior of said vessel, said pipe means comprising a substantially rectangular pipe member of substantially rectangular exterior and interior dimensions, having a major exterior side length D1 and a minor exterior side length D2 and a major interior side length D3 and a minor interior side length D4, further having plug means situate at a distal end thereof for preventing egress of said liquid-gas mixture vertically downward from said distal end;
at least two apertures situate in said rectangular pipe member and disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said liquid-gas mixture substantially horizontally outwardly from said pipe means, of combined cross-sectional exit area A e; and said exit area A e of said apertures defined as a function of widths D1, D2, D3, and D4 and said cross-sectional area A i of said pipe means, wherein A e substantially equal to:
A i × [D3 + D4]/[D1 + D2]

42. The apparatus as claimed in claim 41, said rectangular pipe member having an exterior circumference C, wherein said apertures comprise cylindrical apertures each of diameter D A, where D A is less than A i/C.

43. The apparatus as claimed in claim 41, said pipe member having an exterior circumference C, wherein said apertures comprise a pair of horizontally-extending rectangular slots in said pipe means, disposed on substantially mutually opposite sides of said pipe means, each of a width substantially equal to said maximum interior width D i of said pipe means, and each of a vertical depth no greater than A i/C.

44. An apparatus for creating microbubbles of gas in a liquid the majority of which are in the approximate size range of 5 to 100 µm, comprising:
means for introducing gas bubbles the majority of which are of a size between microns and 3 mm into said liquid to form a liquid-gas mixture;
a containment vessel having a substantially longitudinal axis adapted to be positioned vertically and contain a volume of gas in an upper portion thereof under a second pressure of at least 20 psig;
elongate, hollow pipe means, having a longitudinal axis and substantially symmetrical in cross-section so as to have identical moments of inertia about at least two axis in a cross-sectional plane through said pipe means, of substantially uniform wall thickness, having a maximum interior width D i and a maximum exterior width D o and a cross-sectional area A i, said pipe means situate substantially centrally in said containment vessel and proximate a top end of said containment vessel and extending substantially vertically downwardly within said vessel, adapted for supplying said liquid having bubbles of gas entrained therein under a first pressure greater than said second pressure to an interior of said vessel via a plurality of apertures, and having plug means situate at a distal end thereof for preventing egress of liquid vertically downward from said distal end;
said apertures disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means and each extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said liquid horizontally outwardly from said conduit means into said vessel, of combined cross-sectional exit area A
e; and said combined exit area A e of said apertures defined as a function of widths D i and D o and the interior cross-sectional area A i of said pipe means, wherein A e substantially equal to:
A i × D i/D o

45. The apparatus as claimed in claim 44, said apertures each having a maximum vertical dimension G, said pipe means having an exterior circumference C, wherein G is no greater than A i/C.

46. The apparatus as claimed in claim 45, further comprising a baffle member situate in said vessel, immediately below said plug means of said pipe member, adapted to allow liquid ejected from said apertures to pass therethrough and thereafter to a bottom portion of said vessel.

47. A method for creating microbubbles of gas in a liquid, comprising:
introducing gas bubbles the majority of which are of a size between 100 microns and 3 mm into said liquid to form a liquid-gas mixture;
directing said gas-liquid mixture into a hollow pipe member, said pipe member having a maximum interior width D i and a maximum exterior width D o, said pipe member situate proximate an upper portion of a containment vessel and extending into an interior of said containment vessel, said upper portion of said containment vessel containing said gas being under a second pressure of at least 10 psi, and a bottom portion of said containment vessel substantially containing said liquid-gas mixture;
injecting said gas-liquid mixture under a first pressure exceeding said second pressure via said pipe member, into said containment vessel;

spraying substantially radially outwardly from said pipe member said gas-liquid mixture into said upper portion of said containment vessel via at least two apertures in said pipe member, said at least two apertures in said pipe member in communication with said gas-liquid mixture in said pipe member and having a combined area A e sized as a function of a maximum interior widths D i and maximum outside width D o and a cross-sectional area A
i of said pipe member, wherein A e is substantially equal to:
A i × D i/D o and removing from said containment vessel said liquid-gas mixture having microbubbles of gas entrained therein.

48. The method as claimed in claim 47 further comprising the step of containing within said bottom portion of said vessel said gas-liquid mixture with microbubbles entrained therein and withdrawing said gas-liquid mixture from said bottom portion of said vessel at a rate approximately equal to a rate at which said gas-liquid mixture is introduced into said containment vessel via said pipe member.

49. The method as claimed in claim 48, wherein said rate of withdrawing said gas-liquid mixture from the bottom portion of said vessel is substantially at a rate which microbubbles entrained in said gas-liquid mixture rise in said vessel, so that at a time when gas-liquid mixture is removed from said bottom portion of said vessel said microbubbles will have travelled upwardly a distance through said gas-liquid mixture substantially equal to a majority of a depth of gas-liquid mixture in said bottom portion of said vessel.

50. The method as claimed in claim 47 or 48, further comprising the step of passing said gas-liquid mixture sprayed from said pipe member through a baffle plate member positioned in said containment vessel below said pipe member and intermediate said upper portion and said bottom portion of said containment vessel, and adjusting the rate of injection and removal of gas-liquid mixture from the vessel so that baffle plate member is positioned above the level of the liquid in the vessel.

51. The method as claimed in claim 47 or 48, further comprising the method of maintaining the pressure of the vessel in the upper portion thereof at a pressure of at least 15 psig.

52. The method as claimed in claim 47 or 48, said step of spraying substantially radially outwardly said gas-liquid mixture into said upper portion of said containment vessel via at said apertures further comprising spraying said gas-liquid mixture against sides of the containment vessel.

53. The method as claimed in claim 47 or 48, wherein said step of spraying said liquid/gas mixture into said containment vessel via said apertures is carried out by apertures each having a maximum vertical dimension G, said pipe means having an exterior circumference C, wherein G is no greater than A i/C.

54. The method as claimed in claim 47 or 48 wherein said gas is air.

55. A method for converting a liquid-gas mixture having bubbles of gas therein the majority of which are of a size between 100 microns and 3 mm to a liquid-gas mixture having microbubbles of gas therein the majority of which are of an average size between 5-100 microns, comprising the steps of:
directing said gas-liquid mixture having bubbles of gas therein the majority of which are of a size between 100 microns and 3 mm into a hollow, substantially vertical pipe member, having a maximum interior width D i and a maximum exterior width D o;
spraying said gas-liquid mixture substantially radially outwardly from said pipe member via a plurality of apertures in said pipe member, so that said gas-liquid mixture contacts a vertically extending surface;

said plurality of apertures in said pipe member in communication with said gas-liquid mixture in said pipe member and having a combined area A e, said apertures sized as a function of said maximum interior width D i and said maximum outside width D o and a cross-sectional area A i of said pipe member, wherein A e is no greater than:
A i × D i/D o collecting a resulting gas-liquid mixture having microbubbles of gas entrained therein in a vessel, under a pressure of at least 10 psig; and removing said gas-liquid mixture from said vessel.

56. A method for continuously purifying a liquid containing impurities by exposing said liquid and impurities for a time in a substantially vertical containment vessel to microbubbles of gas in the range of 5 to 100 microns in diameter, comprising the steps of:
directing a gas-liquid mixture containing impurities and bubbles of gas the majority of which are of a size between 100 and 3mm into a hollow pipe member, said pipe member of uniform thickness and having a maximum interior width Di and a maximum exterior width Do and identical moments of inertia on two axis in a plane of cross-section through said pipe means, said pipe means situate proximate an upper portion of said containment vessel and extending vertically downwardly in an interior of said containment vessel, said upper portion of said containment vessel containing said gas, and being under pressure of at least 15 psig;
injecting said gas-liquid mixture, under a pressure of at least 5 psig higher than said gas in said containment vessel, into said vessel via said pipe member;
spraying said gas-liquid mixture substantially horizontally outwardly from said pipe member into said upper portion of said containment vessel via a plurality of apertures in said pipe member so that said gas-liquid mixture contacts interior sides of said vessel;

said plurality of apertures in said pipe member in communication with said gas-liquid mixture in said pipe member and having a combined area A e, said apertures sized as a function of said maximum interior width D i and said maximum outside width D o and a cross-sectional area A i of said pipe member, wherein A e is no greater than:
A i × D i/D o collecting said gas-liquid mixture, now having microbubbles of gas entrained therein the majority of which are now of a size less than 100 microns in diameter, in a bottom portion of said containment vessel;
removing, from said bottom portion of said vessel, said liquid with gas microbubbles entrained therein at a rate which said microbubbles entrained in said liquid rise in said vessel so as to permit said gas microbubbles time to react with impurities in said liquid; and supplying said liquid-gas mixture to said pipe member substantially at a rate at which said liquid-gas mixture having gas microbubbles entrained therein is removed from the bottom of said vessel.

57. The method as claimed in claim 56, wherein said step of spraying said liquid-gas mixture into said containment vessel via said apertures is carried out by apertures each having a maximum vertical dimension G, said pipe means having an exterior circumference C, wherein G
is no greater than Ai/C.

58. The method as claimed in claim 55, 56, or 57, wherein Ae is substantially equal to Ai ×
Di/Do.

59. A method for providing a supply of a liquid/gas mixture having gas bubbles entrained therein the majority of which are of a size less than 100 microns, comprising the steps of:

introducing gas bubbles the majority of which are of a size between 100 microns and 3 mm into a liquid to form a liquid-gas mixture;
directing said liquid-gas mixture into a hollow pipe member, said pipe member of uniform thickness having a maximum interior width D i and a maximum exterior width D o and interior cross-sectional area A i and identical moments of inertia in a plane of cross-section through said pipe member on two separate axis, said pipe member situate proximate an upper portion of a containment vessel and extending into an interior of said containment vessel, said upper portion of said containment vessel containing said gas being under a pressure of at least 10 psig;
spraying substantially radially outwardly from said pipe member said liquid-gas mixture into said upper portion of said containment vessel via at least two apertures in said pipe member, said apertures having a combines area A e wherein A e is no greater than A i × D i/D o;
collecting said liquid-gas mixture when expelled from said apertures in a bottom portion of said vessel; and removing from said bottom portion of said containment vessel, at a vertical position immediately below a lowermost level in said vessel which bubbles of a size larger than 100 microns initially fall to before rising in said vessel, and at a level on said bottom portion of said vessel which bubbles of a size less than 100 microns initially fall to before rising in said vessel.

60. An apparatus for converting a first liquid-gas mixture having bubbles of gas therein the majority of which are of a range from 100 microns to 3 mm in size to a second liquid-gas mixture having microbubbles of gas therein the majority of which are of a size less than 100 microns, comprising:
a containment vessel adapted to contain, in an upper portion therof, a volume of gas under a second pressure exceeding ambient by at least 10 psi;

an elongate, hollow pipe means, having a longitudinal axis and substantially symmetrical in cross-section so as to have identical moments of inertia about at least two axis in a cross-sectional plane through said pipe means, of substantially uniform wall thickness, having a maximum interior width D i and a maximum exterior width D o and a cross-sectional area A i, situate substantially centrally in said containment vessel and proximate a top end of said containment vessel and extending substantially vertically downwardly within said vessel, adapted for supplying said first liquid-gas mixture having bubbles of gas entrained therein under a first pressure greater to an interior of said vessel under a second pressure less than said first pressure but greater than ambient via a plurality of apertures, and having plug means situate at a distal end thereof for preventing egress of liquid vertically downward from said distal end;
said apertures disposed in one or more planes each substantially perpendicular to a longitudinal axis of said pipe means and each extending from an interior of said pipe means to an exterior of said pipe means, each adapted to direct said first liquid-gas mixture substantially horizontally outwardly from said conduit means to form said second liquid-gas mixture, of combined cross-sectional exit area A e; and said combined exit area A e of said apertures defined as a function of widths D i and D o and the interior cross-sectional area A i of said pipe means, wherein A e substantially less than or equal to:
A i × D i/D o and D o is not greater than 10.0 inches; and said pipe means having an exterior circumference C, and said aperture means having a maximum dimension G, wherein G<=A i/C; and said containment vessel having a lower portion, said lower portion adapted to capture said second liquid-gas mixture having therein gas bubbles the majority of which are of said size less than 100 microns.

61. The apparatus as claimed in claim 60, said aperture means comprising at least two cylindrical appertures, each of diameter D A, wherein D A is not greater than A i/C.
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