US 2333456 A
Description (OCR text may contain errors)
Nov. 2, 1943. s. J. WYNN 2,333,456
METHOD AND APPARATUS FOR PREPARING DIsPERsIoNs Filed 000. 9, 1941 :$14 7J, 26 lw y @I r 46 V 'l A l LJ 96 Mj i lNvEN'roR d .X4/nuez J: W//v/v ATTORN EY Patented Nov. 2, 1943 METHOD AND APPARATUS F'OR PREPARING.
DISPERSIONS Samuel J. Wynn, Riverton, N. J., assigner to- Cities Service Oil Comp any New York, N. Yr., a
corporation of Pennsylvania Application October 9, 1941, Serial No. A414,333
(Cl. 252-314)l f Claims.
This invention is directed to improvements in method and apparatus for preparing fine dispersions of a liquid or a nely a liquid dispersion medium.
A primary object of the presentinvention is to provide method and apparatus whereby to prepare fine dispersion economically with continuous throughput of dispersion ,constituents For continuous formation of fine dispersions or suspensions of solid in liquid, apparatus of the colloid mill has been heretofore generally used. In the colloid mill disintegration and dispersion takes place as a result of high centrifugal and hydraulic shear forces developed in a dispersion forming zone of small area between two Oppositely rotating disks, or betweena rotating disk and a stationary casing. The disks rotate at a relative speed Aof at least 100 ft. per second and high centrifugal stresses are developed.
Fine dispersions or emulsions of immiscible liquids are quite generally prepared by the use of homogenizers which operate to produce dispersions byforcing a coarse dispersion at high linear velocity in a owing stream through an orifice type ow restriction.
divided solid in and anvil which form the flow restriction path should be uniformly vcontoured throughout a substantial area to provide a iilm iiow path of uniform thickness and of substantial width and length.
'I'he direction of film flow may be 'linear across the hammer face from one side to the other of the iiow restriction path, but according to a preferred adaptation of the invention the hammer and anvil faces are respectively of convex and concave conical contour and the lm flow is radial from the apex toward the periphery of the conical clearance zone and in a direction generally counter-current to the forward impact strokes of the hammer, whereby additional surge turbulence is developed within the A more particular object of the present invention is to provide method and apparatus adapted for preparing nely dispersed suspensions and emulsions without the necessity of developing.
either high linear flow velocities or high centrifugal and shear forces. f
According to the present invention a coarse dispersion mixture of the constituents isforced fre'ciprocating. hammer and .a stationary anvil.
The rapidly repeated successive impact and withdrawal strokesA of the hammer face lare in a `to flow as a thin fluid lm at moderate linear defined in the claims.
With the above and other objects andfeatures in View, the invention consists in the improved dispersion forming method and apparatus which is hereinafter described and more particularly In the following description reference will be had to the accompanying drawing, the single figure of which illustrates diagrammatically,
partly in longitudinal section, apparatus reprey senting a preferred embodiment of the invention.
As illustrated in the drawing, the preferredapparatus incorporates a two-sectioned housing IIJv enclosing a chamber' I2 into which a pre.
formed and suitably proportioned coarse dispersion mixture of liquid dispersing medium and of nely divided solid or liquid material to be dispersed is f ed under pressure by pumps 'I4 and I5 through a fe'ed pipe I6. The delivery end of pipe I6 is threaded to engage threads in a central aperture I8 in the top section of the housing.
direction normal to the opposed face of the anvil and normal to the direction of iiow of the film, so
that the restriction to ow and film thicknessl are continuously varied between maximum and minimum limits measured` by `the hammer strokes, at a rate corresponding tothe hammer frequency. The opposed faces of the hammer A conical depression in the top section of the housing forms a smooth stationary anvil face 20 which is shaped and dimensioned to conform with the conical striking face of a hammer 22. Hammer 22 is mounted on a stern or rod 24 for reciprocat'ion within chamber I 2.. A forward extensionf 25 of rod 24 is slidably .ljournaled in aperture I8 as a guide to hold the hammer in central `alignmentwith anvil 20. Rod extension l 25 is provided with an axial bore 26' and communicating radial apertures 28 by which coarse dispersion entering aperture III- may ow into an annular` feed chamber 30 atv the head of 'chamber 2.
The fine dispersion which is produced by radial expansion ow of the coarse dispersion in a thin lm through a flow restriction clearanceI is reduced to ne particle size. lIt will be understood that the workingV faces; of the hammer and anvil may have matched convex and concave curvatures, or may have pyramidal or other suitable shapes, and that thelongitudinal axes of the hammer and anvil may lie in inclined or horizontal planes. A packing gland 36 is shown as disposed centrally in the bottom section of housing I at the point where the housing is apertured to journal the rod 24. The lower end of rod 24 is shown as enlarged to provide a target 31 for receiving successive upwardly delivered impacts of a reciprocating electro-magnetic plunger 38. Plunger 33 may be reciprocated with a short stroke and at high frequency (for example 60 per second or higher) by means of a solenoid 40 or equivalent source, of vibration energy which is only illustrated partially and diagrammatically. Solenoid -40 is shown as disposed in properly spaced central alignment with rod 24 and as clamped in position by' a collar 42 and by extensions of tie u bolts 44 which couple 4the sections of housing i0 \together. .Y
The strokes of energizing plunger 38 and oi hammer 22 may be very short, for example .001-.002 inch. Also the treating zone clearance between the working face of hammer 22 and the opposed working face of the anvil 20 at the upward extremity of the hammer stroke may be very small, for example, .001-.002 inch. Consequently it may be necessary to maintain a considerable pressure differential between feed chamber 30 and outlet pipe 34 to insure continuous flow of dispersion constituents in a thin film into and through the conical treating zone 32 between the hammer and anvil. In order to maintain hammer 22 in suitable low clearance relation to anvil 20 under the high feed pressure obtaining in chamber 30, a centrally apertured bracket A46 straddles rod 24 in adjustably-spaced position below housing I0. `Bracket 46 in turn carries a supporting base 48 for a compresstroke and at a high frequency. The intense beating and surge turbulence which is developed within and propagated by the liquid dispersing medium throughout the entire area of nlm between the hammer and plate surfaces operates in conjunctionwith the radial release of pressure by which the ow is developed through the treating zone, to eiect rapid disintegration and fine dispersion with a relatively lowppower consumption and without substantial power dissipation by friction between the liquid andthe hammer and anvil. l
The apparatus has been designed so treating capacity can be easily regulated in accordance with` the degree of dispersion which is sought and with the characteristics of the dispersion constituents. Adjustment of the rate of dispersion constituent throughput'may be effected primarily by varying the pressure at which the coarse dispersion is supplied to the treating zone, by varying the thickness of fllm flow through the-treating zone, and by varying the vibration frequency ofthe hammer. However, in addition to the above adjustments provided by the apparatus design as illustrated, it will be recognized that to meet a particular problem the area of the treating zone, and consequently the area of the film, can be changed to allow for treating a larger lor: srna1ler volume of dispersion constituents at one time within a film Aof predetermined thickness. Also the apparatus design may be changed to provide a longer or shorter'` film flow path, whereby to vary the number of hammer blows which can be imparted to a unit volume `of dispersion mixture owing through the treating zone to thereby regulate thedegree of dispersion eifected during the period of sojourn of the dispersion mixture in the treating zone.
According to the preferred apparatus design illustrated, the direction of ow of dispersion constituents through the treating zone is generally countercurrent to the ,direction of movement of the hammer on its forward or compression stroke. Under any design including the Xpreferred design illustrated, the forward stroke of the hammer operates to squeeze the lm and effect a temporary reversal of ow of the dispersion coil`spring 50. The top` of spring 50 supports a collar 52 in tight engagement with a shoulder 54 of rod 24. By adjusting the position of bracket 46 the tension of spring 52 may be varied to counterbalance the` pressure diifersion constituents in the treating zone, and to develop an inertia to forward owduring and immediately following each forward hammer stroke. Consequently the rate of ow of coarse dispersion into and through the treating zone bears an inverse proportional relation to the vibrational frequency of the hammer. With the pumps I4 and YI5 developing a high pressure suillcientto force the coarse dispersion as a flowing lm through the restricted treating zone, and
a treating zone 32 of small cross-section and ex- Y tensive area, and simultaneously subjected to the disintegration effect of rapidly repeated successive impact compression and withdrawal expension forces applied at substantially right angies to the direction of flow;k These forces are applied by a reciprocating hammer operating opposite a stationary anvil plate with a very short with the hammer operating alternately in a di-l rection with the forward flow to speedup such forward ow and'to widen the flow path (during the withdrawal stroke), and to reduce the ow path and force reversal of the directionl of uid ow during the forward stroke, it will be appreciated that intense alternate compression squeezing and expansion cavitation forces are developed in the ilowing fllm between the hammer and anvil, and that intense"wre drawing forces are also developed in directions generally parallel to the direction of iluid flow. All of these forces cooperate to produce extreme turbulence and rapid effective disintegration and dispersion of the constituents throughout the area of the treating zone.
The term substance" has been used in the claims to denne a solid, or a liquid which is imthat its anvil.
miscible with, the other liquid in which it is to be dispersed.
The inventicnhavlng what is claimed as new is: `1-. A method of preparing line dispersions of asubstance of the class consisting of a solid and a liquid immiscible with the liquid with which it is to be admix'ed whichl comprises, forcing a coarse dispersion stream of the substance and liquid to'ilow in a conilned streamI as a thin lm through a flow restriction clearance'zone of substantial area and length, and subjecting said film to rapidly repeated alternate squeezing and expansion forcesby alternately increasing and decreasing said clearance within narrow limits at Ka frequency sufiiciently high to develop intense surge turbulence within the lm to thereby effect ilne dispersion formation.
2. A method of preparing ne dispersions of a substance of the class consisting of a solid and a -liquid immiscible with the liquid with which it iS to be admixedwhich comprises, forcing a coarse dispersion stream of the substance and liquid to ow in a confined stream-as a thin film through a ilow restriction zone of substantial area and length,` and subjecting said lm to rapidly repeated Valternate compression and expansionforces at a frequency sulciently high to develop intense surge turbulence within the film to thereby effect fine dispersion formation,
' 3. A method of preparing netdispersions which comprises, forming a coarse dispersion 'mixture of a substance of the class consisting of solids and liquids and a liquid which is-immisciblel with the other liquid of the said Vdispersions and mantaining ilowof a Iconfined stream thereof in a thin film through a iiow restriction vtreating zone of substantial -area and length, and continuously varying the thickness of said film bey tween maximum and minimum limits and sub- Jectin'g the mixture therein to rapidly repeated alternate compression and expansion forces actingicountercurrent-to the 'direction of flow of the stream at a frequency suiiiciently high to develdp intense surge turbulence within the film to thereby effect disintegration' and fine dispersion formation. ip-In dispersion forming, apparatus, two relatively reciprocable members having oppositely disposed .uniformly contoured 'working faces forming therebetween a uidj-'flow restriction clearance zone of substantial area and length,
means for varying` said clearance 'betweenY re'` strictedmaximum Vand minimum limits by re" ciprocation of at least one of said members at high frequency.' and a pump and connections arranged to force a preformed 'coarse dispersion to vflow as a fluid stream in a thin illm through the nowl restriction clearance zone. y v
,5c-In dispersion forming apparatus, a hammer, for reciprocating the hammer, a closed pressure tight surrounding the hammer as onwailastationaryanvil face to conform to tne striking face of .the hammer and disposed in close clearance relation thereto. to cause a dispersion mixture to pass betweenthe faces as a thin film, together with -means for forcing a coarse dispersion of rial to be dispersed and aliquid dispersing inediunder pressureinto the` chamber and through the clearance been thus :described,".
space between the hammer and 6. In dispersion forming apparatus, a chamber having an anvil as one wall, a hammer mounted for reciprocation within said` chamber, means for imparting short stroke blows at high fre- `quency to saidV hammer, said anvil and.hammer having oppositely. disposed uniformly contoured and dimensioned working` faces,` and means for forcing apreformed coarse dispersion as a fluid stream in a thin lm through the clearance space between said working faces. 7. In apparatus for forming dispersions, a
, chamber, a hammer mounted on a stem for reciprocation within said chamber, an anvil plate inner wall for said chamber ,disposed in parallel close clearance relation to the working face of thehammer, the oppositely disposed faces of said plate and hammer being shaped 'to form therebetweena dispersionforming zone of substantial area and uniform clearance,'means outside the 20 chamber for imparting successive impacts at high frequency to the hammer stem; means for forcing a preformed paarse dispersion to ow in a' confined stream as a thin lm into and through the clearance space between said plate and hammer, and fmeans for adjusting said clearance.
8. In dispersion-forming apparatus, a "closed pressure tight treating chamber, a hammer mounted for reciprocation within said chamber,
, means to reciprocate the hammer with a short stroke at high frequency, a wall for said chamber having a lining shaped to form an anvil face which conforms in contour with the striking face moun ed within said chamber, means to recipro cate the hammer with a short strokeat yhigh frequency, a .wall for `said chamber having a lin.-
l in g shaped to form an anvil'face which conforms in contour with the striking face of the hammer and which is disposed in close clearance relation thereto to cause a1 dispersion mixture to pass between the faces as a thin lm, a pump and connections for forcing a coarse dispersion mixture a to owl as a stream through the,clearance space A between the hammer and anvil, and means for adjusting'the'clearance between the hammer and the anvil. A 10. In dispersion formmg apparatus, a treating chamber, a hammer mounted for reciprocation within said chamber through a short stroke at im high frequency, a wall for said `chamber having" a lining shaped to' form an anvil face which coriforms in contour withthe 'striking' face ofthe hammer and which is disposed in close clearance relation thereto, a pump^` and connections for forcing a coarse dispersion mixture to flow-in a' confined stream as a thinlm through the clearance space between -the hammer andanvil. and
te said hammer whereby to hold said hammer in adjustably spaced clearance relation-to the anvil against the pressure developing film flow.` i
. `BAMIHIiI.. J. WYNN.
a counter balancing spring operatively connectedv