US3261593A

US3261593A - Fluid mixing process and apparatus

Info

Publication number: US3261593A
Application number: US332095A
Authority: US
Inventors: Thomas D Sharples
Original assignee: Pennsalt Chemical Corp
Current assignee: Pennwalt Corp
Priority date: 1963-12-20
Filing date: 1963-12-20
Publication date: 1966-07-19
Anticipated expiration: 1983-07-19

Description

y 19, 1966 'r. o. SHARPLES 3,

FLUID MIXING PROCESS AND APPARATUS Filed Dec. 20, 1965 2 Sheets-Sheet 1 2 INVENTOR.

THOMAS D. iHARPLES BY A TTORNE Y y 9, 1966 1'. D. SHARPLES 3,261,593

FLUID MIXING PROCESS AND APPARATUS Filed Dec. 20, 1963 2 Sheets-Sheet 2 246 248 244 Fig. 6

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7 k E 2 I 122 l i INVENTOR. 114 1' THOMAS 0. SHARPLES 7 f I I I44 14 V a ATTORNEY United States Patent 3 261,593 FLUID MIXING PROCESS AND APPARATUS Thomas D. Sharples, Lansdale, Pa, assignor to Pennsalt Chemicals Corporation, Philadelphia, Pin, a corporation of Pennsylvania Filed Dec. 20, 1963, Ser. No. 332,095 14 Ciaims. (Cl. 259-4) This invention relates to fluid mixers. More specifically this invention relates to mixers especially adapted for liquids which normally tend to resist mixing into a homogeneous phase.

In the prior art, attempts have been made to provide liquid mixers having no movable parts and especially adapted for mixing liquids which are difiicult to mix. An example of such prior art is shown in the US. Patent 2,645,463 which issued July 14, 1953, on an application by R. F. Stearns. In some prior art devices the separate liquids have been brought into separate agitating or turbulence-creating chambers. From these chambers after having been made turbulent the liquids have passed into a mixing zone. The contact of the turbulent liquid-s in the mixing zone has broken up particles of the two liquids and mixed them. The mixed liquid has discharged from the mixing zone.

For some liquids the turbulence produced in the prior art agitation zones has not produced in the contact of the two liquids the mixing desired. For instance, in the use of such prior art devices with separate high density caustic and vegetable oil the desired degree of mixing has not been achieved. The high density caustic has remained in globules and streamed past the vegetable oil so that the discharge has not been a homogeneous mixture but instead a suspension of large caustic globules in the vegetable oil.

By means of the present invent-ion it is possible to mix liquids in an extremely efficient manner. This is done by creating counter-rotating vortices of the separate liquids and introducing the counter-rotating liquids into a common mixing chamber. In the mixing chamber the two liquids, each having tremendous rotational energy and rotating in opposite senses, violently contact and annihilate their respective velocities.

The efiiciency of the subject of the present invention is marked in contrast to the prior art devices wherein mere turbulence was created in chambers adjacent the mixing chamber prior to the contact of the two liquids. Apparatuses embodying the present invention guide the liquids into smooth, steady swirling vortices demonstrating a tremendous measure of energy relative to the mere turbulence of the prior art means. It can readily be visualized that the liquids having this energy will in contacting and neutralizing their velocities encounter tremendous shear forces, break up and mix with unusual effectiveness. An additional benefit of the means in accordance with the present invention is that the respective vortices may be precisely controlled so that the energy of the contacting streams is equal. Further, because the turbulence is kept to a minimum prior to the contact of the liquids, apparatuses embodying the present invention feature greater stability of operation, and smoother flow.

These and other features of the invention will be evident from the drawings and the following illustrative descrip- Patented July 19, 1966 In the drawings:

FIGURE 1 is a top plan view of an apparatus embodying the invention;

FIGURE 2 is a side elevational view, partly in section, of the apparatus of FIGURE 1;

FIGURE 3 is a sectional view of a modified form of the apparatus embodying the invention and taken on the line 3-3 of FIGURE 4;

FIGURE 4 is a side elevational view, partly in section, of a modified apparatus embodying the invention;

FIGURE 5 is a diagrammatic view of another modification embodying the invention;

FIGURE 6 is a diagrammatic view of still another modification embodying the invention; and

FIGURE 7 is a diagrammatic view of a further modification embodying the invention and especially useful in extraction processes.

Briefly, then, the invention involves at least a pair of adjacent vortex chambers inducing opposite rotation in the liquids to be mixed and a mixing chamber into which the oppositely rotating liquids from the vortex chambers are led to mix.

Referring more specifically to the drawings, an apparatus embodying the invention is shown in FIGURE 1 and generally designated 10. It comprises a first cupshaped vortex housing 12 having a tangential inlet passage 14 about which is secured on the outside of the housing the inlet tube 16. At the opposite end of the apparatus (FIGURE 2) a second vortex housing 18 is provided with a tangential inlet passage shown partlyat 20 around which on the outside of the housing is secured the inlet tube 22. As may be noted from the drawings, the

inlets

16 and 22 are directed toward their respective housings in opposite tangential directions.

Intermediate the two vortex housings is a common mix housing defined by the circular wall 24. An opening in the circular wall has outlet tube 26 secured thereabout.

Further defining the compartments are a pair of

partitions

28 and 30, respectively, which are clamped between the cup-

shaped vortex housings

12 and 18 and the circular wall 24, respectively. The

partitions

28 and 30 are each provided with central apertures which are preferably threaded and receive coaxial discharge conduits or

nozzles

32 and 34. Preferably the nozzle 34 is of greater diameter than the nozzle 32 and its end overlaps the end of the nozzle 32 defining an annular passageway 36 between the two nozzles. Preferably the inner surface of the nozzle 34 flares somewhat outwardly for reasons which will be later explained.

Holding the mixer in assembly is the drawbolt 38 which extends axially and has its opposite ends threaded to receive the compression caps 40 on the outside of the mixer.

The nozzle 34 has been shown in largerdiameter than the diameter of nozzle 32. This is of benefit especially in mixing liquids of substantial difference in density. In use, the liquid of greater density is made toform a vortex in the housing 12 connected with the nozzle 32 of smaller diameter, while the liquid of lesser density is formed into a vortex in the housing 18 connected with the nozzle 34. Thus as the counter-rotating vortices meet in the passageway 36 the contact is enhanced as the heavier liquid tends to move out and the lighter tends to move in. For some applications many of the benefits 0f the invention may be realized by having the nozzles of identical diameter, with a substantial gap between the ends thereof.

The embodiment of the invention shown in FIGURES 1 and 2 is especially adapted for use with low pressures and its operation will be understood by visualizing the delivery of a lighter liquid tangentially into the housing 18 to create smooth swirling action in that housing. Simultaneously the heavier liquid is introduced into the housing 12 through the passage 14 to create a smooth swirling vortex in that housing and rotating in the direction counter to the vortex in the housing 18. The mixer normally operates almost completely filled with liquid except for a vapor core of small diameter in some instances, and it will be understood that by suitable regulation of the respective incoming liquids an equilibrium condition will be achieved wherein the separate liquids pass in swirling movement through the respective nozzles and into the common mix housing 24 from which they are discharged as a single mixed liquid through the outlet 26.

Those skilled in the art will understand that the rotary speed of the separate liquids as they pass through the respective nozzles will be greater than the rotary speed of the liquids at the greatest internal diameter of the

respective housings

12 and 18. This results as the swirling liquid particles moving inward from the periphery of the housing to the lesser radius of the nozzles swirl in advance of the outer particles picking up rotary speed in accordance with the laws of conservation of angular momentum. Thus remarkable rotary speed is achieved at the diameters of the respective nozzles.

In the embodiment shown the nozzle 34 flares outwardly to avoid the entrapment by centrifugal force in the nozzle 34 of heavier liquid discharging through nozzle 32.

As shown the

nozzles

32 and 34 may be readily replaced by simply disassembling the unit and unscrewing them, substituting the desired nozzles and reassembling the unit. It will be understood by those skilled in the art that the particular shape and size of the nozzles selected will depend on the density of the liquids being mixed, their viscosity, their pressure, and other factors.

Referring now to the embodiment shown in FIGURES 3 and 4, which is especially suited for operating at higher pressures, the structure is generally designated 110. It comprises a pair of

identical end caps

112 and 114 which are each provided with an axial threaded inlet pipe. The pipe of cap 112 is designated 116. The pipe of cap 114 is not shown. The mouths of the end caps are provided with

outward flanges

120 and 122, respectively. These are apertured to receive draw bolts 124.

Within the end cap 112 is disposed a circular vortex chamber defined by the housing wall 128 and the housing end plate 130. Connecting the housing wall 128 and the end plate 130 are a plurality of spaced flow directing vanes 132 disposed at a uniform radial distanc from the axis and evenly spaced thereabout. The end plate 130 is centrally apertured and receives a hub 134 having a central bore. As shown the housing wall 128 has a central opening and an axial downward extension 136 which corresponds to the discharge conduit or nozzle 32 of the first embodiment. The lower end of the extension 136 bears an outward flange and its lower radial face is provided with a number of concentric annular ribs 138.

The lower end of the mixer 110 is very similar to the upper end. It comprises a second vortex chamber defined by a housing wall 142 and an end plate 144 spaced therefrom. Connecting the end plate 144 and the housing wall 142 are a plurality of flow directing vanes 146 directed oppositely from the vanes 132 of the first vortex chamber. Disposed centrally in an opening in the end plate 144 is the hub 148.

The housing wall 142 has a central opening and is formed with an axial extension 150 toward the extension 136. The upper end of the extension 150 is formed with 4 an outward flange which presents on its upper radial face a number of concentric ribs 152 which interfit with the ribs 138 of the extension 136.

Holding apart the

housing walls

128 and 142 is the circular mix housing wall 154 which may be reduced adjacent its ends to provide shoulders engaging the mouths of the end caps 112 and 114, respectively. A mix housing outlet tube 156 is provided.

Holding the parts which define the vortex chambers in proper position is the draw bolt 158 which passes through the hub 134 and threadedly engages the hub 148. The

hubs

134 and 148, for instance, may be formed to help direct the vortices into the nozzles.

The operation of the higher pressure version of the apparatus as shown in FIGURES 3 and 4 may be readily visualized. The liquids to be mixed are connected respectively to the axial inlet pipes of the

caps

112 and 114, and a supply of the respective liquids is made to flood the two vortex chambers within the flow directing vanes respectively. In passing inward through the

vanes

132 and 146 the liquids are deflected in a more or less tangential path to cause a swirl movement within the respective chambers. Since the

vanes

132 and 146 are oppositely directed, the swirling vortices will be in opposite directions. These flow directing vanes may take different forms and have diiferent angles, i.e., air foil shapes, slots and even adjustable angle construction. As the respective liquids pass through the conduits defined by the extensions 136 and they swirl at rotary rates above those at the periphcries of the respective vortex chambers in accordance with the law of conservation of angular momentum. As the counter-rotating liquids contact each other in the space between the

ribs

138 and 152 violent mixing action occurs to the extent that virtual annihilation of the rotary speed of the respective liquids with high and intense shear ensues. After such mixing. the mixed liquids are drawn off through the outlet pipe 156.

As shown in FIGURE 4 the inside face of the extension 150 comprising the conduit for the vortex of low density liquid may flare outwardly upward for the purpose as explained in connection with the earlier embodiment.

A further variation embodying the invention is shown in the mixer of FIGURE 5. In this embodiment, easily fabricated from glass, for instance, designated 200, a first vortex chamber is shown at 210 and a second at 212. The

inlets

214 and 216 respectively to those two chambers direct the liquid oppositely to induce counter-rotation. As shown the

outlets

218 and 220, respectively, deliver their energy-laden vortices to the mixing chamber 222. Preferably the liquid of greater density is delivered through outlet 218 of smaller radius than the outlet 220 through which the lighter liquid flows out; thus the respective densities cause the lighter liquid to move in and the heavier out, enhancing the contact. The outlet 220 may be flared for reasons stated. As with the other embodiments the counter-rotating character of the two liquids as they enter the mix chamber 222 causes excellent mixing through high shear accompanying the virtual annihilation of the respective velocities.

' As shown in phantom in FIGURE 5, a target 224 may be provided in the mix chamber. This target may present annular concentric ribs 226 to deflect the incoming liquids and effect greater commingling to enhance the mixing. The mixed liquid discharges through port 228.

It should be understood that in some of the earlier embodiments a comparable third component feed means 230 may be used, especially in low pressure operation. If the operation of the embodiment is at a higher pressure it may be necessary to inject the third component under pressure.

A further embodiment of the invention is shown in the variation of FIGURE 6 wherein the mixer 240 comprises an in-line swirl-inducting bafiie 242 which forms the liquid into a forced vortex immediately downstream.

As shown the bafile 242 may comprise a simple plug having screw-shaped passages. Downstream from the baflle 242 is a vortex chamber 244 which guides the incoming second component at 244a into a swirl rotating counter to the swirl of the first liquid. The counter rotating vortices meet in the mix zone 246 and their respective velocities are-virtually annihilated as they move downstream to the outlet 248.

It should be noted that preferably the liquid of greater density is introduced into the mixer through the bafile 242 so that the lighter liquid which enters the vortex chamber 244a will have a tendency to displace the heavier liquid by moving inward, thus enhancing the mixing action. As with the earlier embodiments the mixing action may be precisely controlled by adjusting the respective pressures of the light and heavy liquid as they are introduced into the mixer.

A further embodiment is designated 250 and is shown in FIGURE 7. This embodiment is especially useful in countercurrent extraction processes wherein a number of countercurrent extraction stages are cascaded. In the embodiment the mix from an earlier stage is introduced tangentially to the cyclone 260 at 260a. The underflow from the cyclone 260 discharges at the lower end of the cyclone and possesses considerable rotational energy. A light liquid with which it is desired to contact the underflow is delivered to the vortex chamber 262 in a tangential inlet 262a to create in the chamber 262 a vortex having rotational energy in the opposite direction from that of the underflow from the cyclone 260. In the mix chamber 264 the two liquids contact. It will be noted that the outlet from the underflow is of smaller diameter than the outlet nozzle for the chamber 262 to enhance the mixing action as with earlier embodiments. From the mix chamber 264 the discharge mixture may be separated centrifugally in the next stage of extraction. The centrifugal separation may be effected by cyclone or centrifuge.

The overflow from the cyclone 260, possessing rotary energy imparted to it by the cyclone 260, is delivered to the mix chamber 266. A liquid of greater density with which it is desired to contact this overflow is delivered tangentially to the vortex chamber 268 through passage 268a so as to guide the heavy liquid into a vortex having rotary energy in the opposite sense of direction from the overflow from cyclone 260. It will be noted that the heavy liquid is delivered in the mix chamber 266 at a lesser radius than the lighter overflow from cyclone 260 to enhance the mixing. From the chamber 266 the mixed liquid discharges through port 270 for delivery to a centrifugal separator which may comprise the next stage of extraction. It will be noted that in the FIGURE 7 embodiment the cyclone 260 itself represents one of the vortex-forming chambers and that the cyclone imparts the desired rotary energy to the incoming liquid.

From the above illustrations it will be clear that I have developed an extremely simple and inexpensive mixer having no moving parts and which is especially suited to achieve an eflective mixing of liquids which have a tendency to resist such a mixing. The mixer of my invention may take many forms.

It is to be understood that the above particular description is by way of illustration and not of limitation, and that changes, omissions, additions, substitutions, and/or other modifications may be made without departing from the spirit of the invention. Accordingly, it is intended that the patent shall cover, by suitable expression in the claims, the various features of patentable novelty that reside in the invention.

I claim:

1. A fluid mixer comprising at least two vortex housings each having an inlet directing incoming fluid to one side of the axis thereof for producing vortices rotating in opposite senses of direction when viewed from one end of the mixer, a mixing housing, wall means separating each vortex housing from the mixing housing, the Wall means having central openings permitting communication from the vortex housings, respectively, directly with the mixing housing, the mixing housing having an outlet for mixed fluids.

2. A liquid mixer comprising a pair of coaxial generally circular vortex housings having inlet passages for separate liquids entering the housings from directions to produce opposite rotational movement of liquid within the housings when viewed from one end of the mixer, a mix housing, wall means disposed between each vortex housing and the mixing housing, respectively, the wall means having central axial discharge conduits extending directly into the mix housing, the mix housing having an outlet for mixed liquid.

3. A liquid mixer as described in claim 2 wherein the central axial discharge conduit from one of the vortex housings is smaller in diameter than the conduit from the other.

4. A liquid mixer as described in claim 2 wherein one of the central discharge conduits flares outwardly into the mix housing.

5. A liquid mixer as described in claim 2 wherein the mix housing is intermediate the vortex housings.

6. A liquid mixer as described in claim 2 wherein the mix housing is disposed on the opposite side of one of the vortex housings from the other vortex housing.

7. A liquid mixer as described in claim 6 wherein one of said vortex housings has an axial inlet through which a third component can be introduced into said mixer. I

8. A liquid mixer as described in claim 2 wherein the inlet passage for one of the vortex housings is in the form of a screw-shaped balfle.

9. A liquid mixer as described in claim 2 wherein the mix chamber is provided with a radial surface having concentric annular ribs against which at least one of the discharge conduits directs a discharge from one of the vortex housings.

10. A liquid mixer as described in claim 2 wherein one of the vortex housings is defined about its periphery by spaced generally tangential vanes.

11. A liquid mixer as described in claim 2 wherein one of the vortex housings is a cyclone.

12. A liquid mixer comprising a pair of coaxial generally circular vortex housings having respectively opposite tangential inlet passages directing liquid and inducing vortical flow within the vortex housings of opposite senses of rotation, respectively, when viewed from one end of the mixer and confronting axial outlet nozzles, one of the nozzles being smaller in diameter than the other and extending thereinto, the larger nozzle flaring outwardly as its distal end is approached, a mix chamber intermediate the vortex housings and enclosing said nozzles and being provided with an outlet for mixed liquid.

13. A process for mixing two liquids of diflerent densities comprising the steps of forming separate but adjacent counter-rotating vortices of the two liquids, withdrawing central portions of each vortex into a common mixing zone disposed coaxial with the vortices, the liquid of greater density being withdrawn from its vortex at a lesser radius than the liquid of lesser density, and withdrawing the mixed liquids from the mixing zone.

14. A process for mixing two fluids comprising introducing the respective fluids to free-vortex-forming zones along imaginary lines to one side of the axes of the zones, respectively, the lines and related zones being generally in planes perpendicular to the axes of the zones respectively and at distances from the axes of the zones, respectively, to produce counter-rotating free vortices in the zones respectively, withdrawing from each zone a central portion only of each vortex of outside radius smaller than the distance from the axis to the line of 3,261,593 7 8 the said zone, delivering each portion directly into a FOREIGN PATENTS common mixing zone and Withdrawing the mixed fluids 529 512 7/1931 Germany from the mixing zone.

716,594 10/1954 Great Britain.

References Cited by the Examiner 5 I UNITED STATES PATENTS WALTER A. SCHEEL, Przmaiy Examzner.

2 043 10 193 MaureL IRVING BUNEVICH, Examiner. 2,831,754 4/1958 Manka 259-4 XR 3,047,275 7/1962 COX 259 4 J. M. BELL, Assistant Examiner.

Claims

1. A FLUID MIXER COMPRISING AT LEAST TWO VORTEX HOUSINGS EACH HAVING AN INLET DIRECTING INCOMING FLUID TO ONE SIDE OF THE AXIS THEREOF FOR PRODUCING VORTICES ROTATING IN OPPOSITE SENSES OF DIRECTION WHEN VIEWED FROM ONE END OF THE MIXER, A MIXING HOUSING, WALL MEANS SEPARATING EACH VORTEX HOUSING FROM THE MIXING HOUSING, THE WALL MEANS HAVING CENTRAL OPENINGS PERMITTING COMMU-