[0001] This invention relates to a mixing device which is of particular utility for the
mixing of fluid components whilst they undergo some species of chemical or physical
reaction, or other time-related process, such that it is important to control the
residence time of the fluid components in the mixer. The mixer which forms the subject
of the present application has been evolved primarily for use in formulating and mixing
photographic emulsions, although the mixer may also find utility in other chemical
processes or in the manufacture of pharmaceuticals, for example.
[0002] In a preferred embodiment of the invention, utilised in the manufacture of photographic
emulsion, the mixer being utilised at a stage in the process in which the input to
the mixer is provided by a nucleation device, such as that disclosed in EP-A-0 734
761 which provides, to an input of the mixer of the invention, a fluid emulsion precursor
comprising a fluid gelatine solution carrying minute crystals or "seeds" of silver
halide, the solution further comprising a mixture of as yet unreacted components of
the emulsion, principally halogen salts and silver nitrate. The function of the mixer
embodying the invention, in this scenario, is to mix the components of the emulsion
continuously so as to ensure, so far as possible, uniform silver halide crystal growth
over a predetermined reaction time and to supply further halogen salts and silver
nitrate solution in a controlled manner to the emulsion passing through the mixer
so as to ensure.a progressive and controlled growth of the silver halide crystals
or "grains".
[0003] According to the invention there is provided a mixing device, particularly suitable
for mixing inter-reactive fluids over a predetermined period on a continuous flow
basis, the device comprising a vessel which is generally cylindrical about a central
axis thereof and has an end wall perpendicular to said axis, and a cylindrical peripheral
wall coaxial therewith, the depth of said vessel measured along the axis being small
in relation to the diameter measured perpendicular to said axis, the device including
a stirring device which is rotatable within the vessel about said central axis the
stirring devices comprising a central portion and a plurality of bars extending radially
from the central portion, each bar extending from the central portion to a position
closely adjoining the peripheral wall and having a height approximately half that
of the peripheral wall, such that when the stirring device is rotated about said central
axis through fluid contained in said vessel, the resulting mixing and turbulence is
such as to minimise radial displacement of any particle of such fluid by the stirring
device, as compared with displacements perpendicular to a radius through such particle
relative to said axis, said vessel having an inlet port opening into the vessel and
an outlet port from the vessel, one of said ports being disposed substantially on
said axis and the other of said ports being disposed at the periphery of the vessel,
whereby, in operation, with the stirrer rotated about said axis, the fluid flowing
from one said port to the other is caused to follow a spiral path, about said axis,
in the vessel.
[0004] An embodiment of the invention is described below by way of example with reference
to the accompanying drawings, in which:-
Figure 1 is a schematic perspective view, partly in phantom, illustrating a mixer
embodying the invention,
Figure 2 is a schematic axial section view of the mixer,
Figure 3 is a schematic plan view of a part of a photographic emulsion manufacturing
plant incorporating the mixer,
Figure 4 is a partial, less schematic view, in axial section, through a preferred
embodiment of the mixer,
Figure 5 is a fragmentary plan view of a portion of the mixer of Figure 4 with a cover
portion thereof removed,
Figure 6 is a fragmentary side elevation view, as viewed in the direction of the arrow
VI in Figure 5,
Figure 7 is a plan view of a solution injector incorporated in the mixer of Figures
4 to 6,
Figure 8 is an end view of the injector of Figure 7,
Figures 9 and 10 are respectively an underneath plan view and a side view of a component
of the injector,
Figure 11 is a schematic axial section of the interior of the mixer,
Figure 12a shows a modified mixing bar;
Figure 12b is a cross section through Figure 12a
Figure 13 is a schematic axial section view of the interior of the mixer.
Figure 14 is a fragmentary plan view of the mixer with the lower portion removed,
and
Figure 15, 16 and 17 illustrate further shapes and cross sections of bars that may
be used.
[0005] Referring to the drawings, the mixer comprises a hollow casing having the general
form of a flat circular disc or plate, within which rotates, about the central axis
of the disc, a stirring device comprising a plurality of bars extending radially within
the casing from a central shaft rotatably mounted in the casing to adjacent a peripheral
wall of the casing. For convenience, the mixer illustrated is hereafter referred to,
for convenience, as a "plate mixer".
[0006] Referring more particularly to Figures 1, 2 and 4, the mixer, indicated generally
at 10, comprises top and bottom walls 12 and 14 each in the form of a flat circular
metal plate, the top and bottom walls being arranged parallel with one another and
spaced apart axially by a cylindrical side wall 16 coaxial with the walls 12 and 14.
The top and bottom walls, 12 and 14, may be provided with ribs as shown in Figure
11. These ribs stop radial flow at the surfaces of the walls. As illustrated in Figure
4, the side wall 16 may be welded along its lower edge to the bottom wall 14 and the
top wall 12 may be detachably secured to the top edge of the side wall, with the interposition
of a suitable gasket or sealant, by tie bolts, (not shown), extending through the
walls 12 to 14 adjacent their peripheries and arranged at intervals around the mixer,
so that when necessary, e.g. for access for cleaning or repair, the top plate may
be detached from the remainder.
[0007] As will be noted, the top, bottom and side walls thus define between them a chamber
of generally cylindrical configuration which is of a diameter substantially greater
than its axial length, for example ten or more times greater.
[0008] Mounted within this chamber is a stirrer assembly comprising a plurality (four in
the example illustrated) of cylindrical stirrer bars 20 extending radially from a
central shaft 22, which is coaxial with the mixer casing and is mounted for rotation
with respect to the casing about the axis of the casing. Each stirrer bar extends
from the shaft 22 to a position closely adjoining the side wall 16 and may, as shown,
be spaced equally from the top and bottom wall. Each bar 20 is of a diameter around
half the axial spacing between the top and bottom walls. The bars 20 may be tapered
to compensate for pressure variations across the radius of the mixer. Pressure variations
may induce unwanted flow paths. Other shapes of bars, with varying cross-sections
may be used, see for example Figures 12a, 12b, 15, 16 and 17.
[0009] As illustrated in Figure 4, the shaft 22 may be rotatably mounted in ball bearings
supported in a bearing housing 26 fitted at its upper end in a central aperture in
the bottom wall 14 and welded or brazed to the wall 14. The bars 20 may, as illustrated,
be integral with (e.g. welded to) to shaft 22 and are preferably arranged at regular
intervals about the mixer axis, (e.g. at 90° intervals, where, as in the Figures,
there are four such bars extending from the shaft 22).
[0010] The top wall 12 has a central discharge port from which extends upwardly a coaxial
discharge duct 28 welded or brazed to the top wall. As shown in Figure 6, the mixer
has a main inlet port in the side wall 16, which communicates with an inlet pipe 32
which may, as shown in Figure 3, extend tangentially with respect to the periphery
of the mixer.
[0011] Referring to Figure 3, in an installation for making photographic emulsion for application
to film or paper the fluid precursors of the emulsion are first treated in a nucleation
device 11 such as described in EP-A-0 734 761 in which small crystal nuclei or "seeds"
of silver halide are formed in the fluid, which is then passed to the mixer 10 for
growing or "ripening" of the "seeds", to form silver halide grains of the desired
size. The fluid from the nucleation device 11 comprises,
inter alia, a solution, in water of gelatine, silver nitrate and halide salt, with the aforementioned
silver halide "seeds" or nuclei in suspension.
[0012] Nuclei produced in the nucleation device 11 are extremely volatile in numbers and
size. Where solution conditions in such an installation are suitable for growth of
seed grains, it is found that whereas large grains increase in size by the "ripening"
process, the smaller grains tend to dissolve so that the larger grains grow at the
expense of the smaller ones. This effect tends to distort the grain size distribution
in ways which are not always desirable. The effect is exaggerated where the solution
conditions are different in different regions of the volume of fluid being processed,
and/or where some portions of the fluid processed are subjected to the "ripening"
process for longer than other portions. In order to preserve the number of grains
produced by the nucleation device 11, the plate mixer 10 enables the grains to be
continually supplied with silver, salt and halide solutions in order that the grains
may ripen without losing numbers.
[0013] The fluid emulsion/solution supplied to the plate mixer flows, in the mixer 11, in
a path which, on a macroscopic scale, has the form of a spiral centred on the mixer
axis as illustrated by the arrows in Figure 1, so that each volume of fluid entering
the mixer
via the inlet 32 travels around the mixer axis several times during its passage from
the periphery of the mixer 10 to the outlet 28 at its centre. Nuclei or grains entering
via inlet 32 thus progress naturally to the outlet port situated in the centre upper
plate of the cylinder. The rotational spiral movement of the fluid within the mixer
from inlet 32 to outlet 28, engendered and maintained by the rotation of the stirrer
bar assembly, is quasi-laminar as viewed in plan so that a "first in first out" pattern
of flow is thus established, i.e. so that each elementary volume of fluid introduced
via inlet 32 follows substantially the same spiral path to the outlet 28 as the preceding
and succeeding such elementary volumes and spends the same time in the mixer as the
preceding and succeeding such elementary volumes. However, as illustrated in Figure
2 the stirrer bars 20, in passing through the fluid in the mixer, produce turbulent
flow in the form of trains of vortices about axes parallel with and close behind the
bars 20 causing them, so that each bar causes mixing, at each radial position along
the bar, substantially only in a plane perpendicular to the radius along which the
bar 20 extends (or rather in a localised region of a notional cylindrical surface
coaxial with the mixer 11). There is thus substantially no stirring in a direction
radially of the plate mixer, so that "first in first out" flow path is not destroyed.
The angular velocity of the stirrer bars may be around twice that of the fluid passing
through the mixer.
[0014] As the fluid emulsion passes through the mixer, the silver halide grains therein,
as they grow, of course remove silver and halide ions from the solution and these
must be replaced in order to allow the grain growth or ripening to continue. To this
end, the top and bottom walls of the mixer are provided with arrays of inlets 40 and
42 respectively through which fresh silver solution and halide solution respectively
are introduced into the mixer and added to the emulsion already circulating therein.
In view of the fact that, as noted above, there is no or very little mixing of the
fluid within the mixer within the plane of the mixer, in order to avoid the occurrence
of spiral bands of different silver and/or halide concentrations in the fluid flow
through the mixer, an ideal arrangement would be for each of the fresh solution inlets
to the mixer to extend continuously along a radius thereof. However, it is also desirable
to control the rate of addition of fresh solution at different radial distances from
the centre of the mixer, which is difficult with a single slot extending radially
from the periphery to the centre of the mixer and fed from a single source. Accordingly,
the fresh solution inlets are contrived of linear arrays of elongate radially extending
slots 40, 42, each of a length small in relation to the radius of the mixer, but with
a radial spacing between adjacent such slots being even smaller, each of said slots
being independently supplied with the respective solution at a controlled rate. In
order to avoid any temporary preponderance of silver solution over halide solution
or
vice versa, the inlets 40, 42, for both solutions are preferably disposed at the same angular
position about the axis of the mixer, the preferred arrangement being, as illustrated,
with the inlets 42 for one solution being provided in the bottom wall and the inlets
40 for the other solution being provided directly above these inlets, in the top wall.
To ensure thorough mixing of the fresh solutions paddle 5 bars may be mounted at different
heights along the bar, as illustrated in Figure 13.
[0015] It will be understood that, in order to prevent premature interaction between the
fresh silver solution and the halide solution fed to the mixer, without the presence
of gelatine, separate inlets are provided for, on the one hand, the silver solution
and, on the other hand, the halide solution. In the arrangement illustrated, (cf.
Figure 2) a single such radial array of radially extending slots 40 is provided in
the top wall 12 of the mixer, for the silver solution and a similar radial array of
radially extending slots 42 is provided in the bottom wall 14 of the mixer for the
sodium or potassium halide solution. In the preferred embodiment, each individual
slot 40 or 42 is supplied with the respective solution by a respective constant delivery
pump, such as a peristaltic pump (not shown). In this preferred embodiment, the peristaltic
pumps comprise respective rotors mounted on a common driving shaft and co-operating,
via rollers carried by the rotors, with respective lengths of resilient, (e.g. rubber
or plastics) tubing. In this arrangement, the delivery rate of each peristaltic pump
is determined by the internal diameter of the respective length of tubing which is
selected, (and the fittings, etc. for such tubing correspondingly selected) to provide
the desired flow rate. However, it will be appreciated that other arrangements may
be equally effective, for example, individual peristaltic or other constant delivery
pumps may be driven by respective electronically controlled motors at appropriately
selected speeds.
[0016] 5 Referring to Figure 5 and Figures 7 to 10, it is convenient to provide the inlets
40 or 42 for each of the fresh solutions in a respective single radially elongate
manifold 50 having an insert portion 54 engaged in a correspondingly shaped radially
elongate slot 52 in the respective top or bottom wall 12, 14 of the mixer. These slots
52 are indicated in Figure 4 (in which the manifolds 50 are not shown), and in Figure
5. As illustrated in Figures 7 and 8, the insert portion 54 may extend from a wider
portion of the manifold block 56 so that a flat face or shoulder 58 is provided which
entirely surrounds the periphery of the insert portion 54 and engages, with the interposition
of a sealing gasket or adhesive/sealant (not shown) the underside of the bottom wall
14, (where the manifold is fitted in the latter with the insert portion 54 extending
upwardly) or the upper surface of the top wall 12, (in the case of the manifold fitted
to the top wall with its portion 54 projecting downwardly from the block 56 into the
respective aperture 52). As illustrated in Figures 7 to 10, the manifold may comprise
three parts, namely a unitary backing block 60 formed with the plurality of vertical
through bores 61 arranged in series along the block 60 and two mating blocks 62 and
64 which between them define a plurality of inlet passages each extending from a respective
said vertical bore 61 to a respective elongate slot 66 in the face of the composite
block (62, 64) remote from block 60. For convenience, in the illustrated construction,
the face of the block 62 facing the block 64 is a plane flat face, the inlets and
slots 66 being formed by grooves or channels cut in the face of block 64 facing block
5 62. In view of this, the row of vertical through bores 61 is displaced laterally
towards the block 64. It will be noted that each groove defining, with the opposing
planar face of block 62, a respective solution inlet terminating in a respective slot
66, is widened and flattened progressively from the face of block 60 to the respective
slot 66, allowing sufficient spacing between the vertical bores in block 60 to accommodate
appropriate connectors leading from the respective pumps, etc. whilst minimising the
radial spacing between adjacent ends of adjacent slots 66 in the manifold. It will
be understood, of course, that the manifold could be constructed in any of a number
of different ways so as to achieve the same or a similar desired configuration.
[0017] The peripheral wall 16 is ideally internally radiused rather than circular. In practice,
provided that the operating conditions are such that the radial depth of each "turn"
of the spiral flow within the mixer is relatively small, appropriate spiral flow conditions
can be maintained with a wall 16 of simple circular shape (as viewed in plan) using
a simple corrective structure at the inlet 32 to the mixer, for example by arranging.for
the inlet pipe to extend tangentially to the peripheral wall of the mixer as illustrated
in Figure 3 and/or by providing, as shown in Figures 5 and 6, a flexible resilient
shim 70 secured at an upstream end thereof to the interior surface of the wall 16,
just upstream of the inlet 32, the upper and lower edges of the shim being closely
adjacent the interior surfaces of the top and bottom walls 12 and 14 respectively
and the shim 70 extending in the circumferential direction for some distance past
the inlet 32, the shim 70 being further so configured that, in an unstressed position,
it is spaced progressively from the wall 16 circumferentially in the direction of
flow within the mixer. With this arrangement, the shim 70 can, if necessary, be deflected
radially outwardly sufficiently by the outer ends of the stirrer bars to allow the
latter to pass during their rotation within the mixer, but nevertheless defines, with
the opposing surface of wall 16, an appropriate volute-like inlet passage for the
emulsion fluid. As indicated in broken lines in Figure 5, the inner surface of the
wall 16 facing the free portion of the shim may be relieved or recessed so as to define
with the shim 70 an inlet passage of substantially constant flow cross section.
[0018] Alternately, and preferably, the structure of the inlet to the mixer may be configured
so that the outer wall of the mixer upstream of the inlet 32 is tapered in a circumferential
direction past the inlet to form a rigid member 68 to guide the inward flow of the
emulsion fluid. The inner side of the outer wall of the mixer downstream of the inlet
and facing the tapered portion 68 may be relieved or recessed as described above.
This arrangement is illustrated in Figure 14.
[0019] Correspondingly, in order to ensure a relatively smooth flow of the fluid emulsion
from the mixer via the outlet 28, the bottom interior surface of the mixer, in the
region immediately opposite the outlet 28, is configured as a chamfered boss or dome
projecting slightly upwardly relative to the major part of the bottom wall. In the
arrangement 5 illustrated, this dome or boss is provided by the upper end of the bearing
mounting block 26 which is fitted in a central aperture in the plate which forms the
major part of the bottom wall 14.
[0020] As illustrated, in order to prevent leakage of the emulsion between the shaft 22
and the bearing block 26, upper and lower seals 82 and 84 are provided, the space
between the upper and lower seals being supplied with pressurised water via ducting
86, with a drain 88 being provided for the escape of any water passing the lower seal
84.
[0021] In operation of the apparatus described, silver nitrate solution and halide solution
are supplied to the inlet slots 66 in order to ripen the nuclei as they progress through
the plate mixer. The flow rate from the inlet slots 66 increases progressively towards
the centre of the plate to keep pace with the maximum possible growth rate which follows
a cube law. (As noted above, these flow rates are determined by the respective peristaltic
pumps).
[0022] In operation, fluid emulsion incorporating gelatine and silver halide grains or seeds
is supplied to mixer 11
via inlet 32 whilst the stirrer 20 is rotated continuously. Fresh silver and halide solutions
are added continuously, as described above, via inlets 40 and 42. Thus, as the mixture
is stirred rapidly by the stirrer bars 20, each elementary volume of fluid in the
mixer passing the inlets 40, 42, at one radial position will have corresponding fresh
amounts of the silver and halide solutions added thereto and will return rapidly,
through the spiral circulation of the fluid in mixer 10, for a further dose of the
fresh solutions, until the respective 5 volume, with its complement of "grown" silver
halide grains, leaves the mixer
via outlet 28. Provided the bars 20 move at a sufficiently high RPM, the function of
the plate mixer will be independent of such bar RPM and only dependent on flow rate
of nuclei and flow rate of silver and halide nuclei for given solution strengths.
[0023] Whilst, for simplicity, reference has been made herein to silver solution, halide
solution, and gelatine, it will be understood by those skilled in the art that many
other significant components will be present in, or added to the emulsion in any practical
emulsion making process, and that some of these components will be present in the
fluid supplied
via inlet 32 and some will be present in the fresh solutions added
via inlets 40 and 42 for example.
[0024] It is anticipated that the plate mixer 11 described will provide nuclei in the desired
numbers, grown to a stable size, in a very repeatable way.
[0025] The mixer described is compact, as compared with 5 the multiplicity of processing
vessels which would traditionally be provided for a similar output, and should require
only minimal maintenance, since the continuous flow of product through the mixer avoids
the need for a regular cleaning phase in the operating cycle. If desired, a plurality
of mixers 11 may be connected in series.
[0026] Where, as in the manufacture of photographic emulsion, the process carried out in
the mixer 11 is temperature sensitive, the temperature of the mixer and its contents
may be maintained readily by housing the mixer within an air chamber with which is
associated air-temperature regulating means, such as a thermostatically controlled
air heater, the conduits leading to inlet 32, from outlet 28 and to inlets 40 and
42 passing through the wall of such air chamber to the mixer.
1. A mixing device, particularly suitable for mixing inter-reactive fluids over a predetermined
period on a 5 continuous flow basis, the device comprising a vessel which is generally
cylindrical about a central axis thereof and has an end wall perpendicular to said
axis, and a cylindrical peripheral wall coaxial therewith, the depth of said vessel
measured along the axis being small in relation to the diameter measured perpendicular
to said axis, the device including a stirring device which is rotatable within the
vessel about said central axis the stirring devices comprising a central portion and
a plurality of bars extending radially from the central portion, each bar extending
from the central portion to a position closely adjoining the peripheral wall and having
a height approximately half that of the peripheral wall, such that when the stirring
device is rotated about said central axis through fluid contained in said vessel,
the resulting mixing and turbulence is such as to minimise radial displacement of
any particle of such fluid by the stirring device, as compared with displacements
perpendicular to a radius through such particle relative to said axis, said vessel
having an inlet port opening into the vessel and an outlet port from the vessel, one
of said ports being disposed substantially on said axis and the other of said ports
being disposed at the periphery of the vessel, whereby, in operation, with the stirrer
rotated about said axis, the fluid flowing from one said port to the other is caused
to follow a spiral path, about said axis, in the vessel.
2. A mixing device according to claim 1 wherein each bar is of constant shape in cross-section
perpendicular to the respective radius.
3. A mixing device according to any preceding claim wherein said outlet is disposed on
the axis of the vessel and said inlet is disposed on the periphery of the vessel.
4. A mixing device according to claim 3 wherein said vessel has at least one further
inlet in said end wall at a position intermediate said axis and the periphery of the
vessel.
5. A mixing device according to any preceding claim wherein said vessel is a closed..vessel
having opposing end walls perpendicular to said axis and a cylindrical peripheral
wall extending between said end walls.
6. Apparatus for processing photographic emulsion including a mixing device according
to any of claims 1 to 6, having a first supplementary inlet or array of inlets in
a said end wall and a second supplementary inlet or array of inlets in a said end
wall, means for supplying to said inlet at the periphery of the vessel a fluid comprising
silver halide grain "seeds", means for supplying to said first supplementary inlet
or array of inlets a fluid component including a soluble halide solution, and means
for supplying to said second supplementary inlet or array of inlets a fluid component
including silver nitrate.
7. Apparatus according to claim 6 wherein said means for supplying said first and second
supplementary inlets comprise constant-mass flow delivery means.
8. Apparatus according to any preceding claim including an air-chamber, means for maintaining
the temperature within said air-chamber at a predetermined value, said mixing device
being disposed within said air chamber, whereby the temperature of the fluid or fluids
within the vessel is correspondingly maintained.
1. Mischvorrichtung, insbesondere zum Mischen interreaktiver Flüssigkeiten über einen
bestimmten Zeitraum hinweg auf einer kontinuierlichen Strömungsbasis, mit einem Behälter,
der im allgemeinen zylindrisch um seine Mittelachse angeordnet ist und eine sich rechtwinklig
zur Achse erstreckende Stirnwand sowie eine koaxial dazu angeordnete zylindrische
Außenwand umfasst, wobei die entlang der Achse gemessene Tiefe des Behälters gering
ist im Vergleich zum rechtwinklig zur Achse gemessenen Durchmesser, wobei die Mischvorrichtung
eine innerhalb des Behälters um dessen Mittelachse drehbare Rührvorrichtung umfasst,
die einen Mittelabschnitt und eine Vielzahl sich radial vom Mittelabschnitt weg erstreckender
Streben aufweist, von denen jede sich vom Mittelabschnitt aus zu einer Position erstreckt,
die der Außenwand benachbart ist, und eine Höhe hat, die etwa halb so groß ist wie
die der Außenwand, derart, dass wenn sich die Rührvorrichtung durch die im Behälter
befindliche Flüssigkeit um die Mittelachse dreht, die sich ergebende Vermischung und
Verwirbelung so ist, dass die radiale Verschiebung eines jeden Partikels der Flüssigkeit
durch die Rührvorrichtung auf ein Minimum reduziert wird im Vergleich zu Verschiebungen
rechtwinklig zu einem Radius durch den Partikel bezüglich der Achse, und wobei der
Behälter einen Zulauf umfasst, der sich in den Behälter öffnet, und einen Ablauf aus
dem Behälter, wobei der eine der Zuläufe bzw. Abläufe im wesentlichen auf der Achse
und der andere am Umfang des Behälters angeordnet ist, wodurch die Flüssigkeit im
Betriebszustand der Vorrichtung und bei Drehung der Rührvorrichtung um die Achse von
einem Zulauf bzw. Ablauf zum nächsten fließt, derart, dass sie um die Achse einer
Spiralbahn in den Behälter folgt.
2. Mischvorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass der Querschnitt einer jeden Strebe rechtwinklig zum jeweiligen Radius konstant ist.
3. Mischvorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Ablauf auf der Achse des Behälters und der Zulauf auf dessen Außenfläche angeordnet
ist.
4. Mischvorrichtung nach Anspruch 3, dadurch gekennzeichnet, dass der Behälter mindestens einen weiteren Zulauf in der Stirnwand aufweist, der sich
in einer Position zwischen der Achse und der Außenfläche des Behälters befindet.
5. Mischvorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Behälter ein geschlossener Behälter ist mit einander gegenüberliegenden, rechtwinklig
zur Achse angeordneten Stirnwänden sowie mit einer sich zwischen den beiden Stirnwänden
erstreckenden zylindrischen Außenfläche versehen ist.
6. Gerät zum Verarbeiten einer fotografischen Emulsion mit einer Mischvorrichtung nach
einem der Ansprüche 1 bis 6, gekennzeichnet durch einen ersten zusätzlichen Zulauf oder eine Anordnung von Zuläufen in einer Stirnwand,
und durch einen zweiten zusätzlichen Zulauf oder eine Anordnung von Zuläufen in der Stirnwand,
mit Mitteln zum Zuführen einer Silberhalogenidkörner-"Samen" enthaltenden Flüssigkeit
zum Zulauf am Rand des Behälters, mit Mitteln zum Zuführen eines flüssigen Bestandteils
aus einer löslichen Halogenidlösung zum ersten zusätzlichen Zulauf oder zur Anordnung
von Zuläufen und mit Mitteln zum Zuführen eines flüssigen Bestandteils aus Silbernitrat
zum zweiten zusätzlichen Zulauf oder der Anordnung von Zuläufen.
7. Gerät nach Anspruch 6, dadurch gekennzeichnet, dass die Mittel zum Zuführen zum ersten und zweiten zusätzlichen Zulauf eine Strömungsfördervorrichtung
für konstante Mengen aufweisen.
8. Gerät nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass eine Luftkammer und Mittel zum Aufrechterhalten der Temperatur innerhalb der Luftkammer
auf einem vorgegebenen Wert vorgesehen sind und dass die Mischvorrichtung innerhalb
der Luftkammer angeordnet ist, wodurch die Temperatur der Flüssigkeit oder Flüssigkeiten
innerhalb des Behälters entsprechend aufrechterhalten bleibt.
1. Dispositif de mélange, particulièrement approprié en vue d'un mélange de fluides inter-réactifs
sur une période prédéterminée sur une base d'écoulement continu, le dispositif comprenant
un récipient qui est sensiblement cylindrique autour d'un axe central de celui-ci
et comporte une paroi d'extrémité perpendiculaire audit axe, et une paroi périphérique
cylindrique présentant le même axe que celle-ci, la profondeur dudit récipient mesurée
suivant l'axe étant petite par rapport au diamètre mesuré perpendiculairement audit
axe, le dispositif comprenant un dispositif d'agitation qui peut être entraîné en
rotation à l'intérieur du récipient autour dudit axe central, les dispositifs d'agitation
comprenant une partie centrale et une pluralité de barres s'étendant radialement depuis
la partie centrale, chaque barre s'étendant depuis la partie centrale vers une position
étroitement contiguë à la paroi périphérique et présentant une hauteur qui représente
approximativement la moitié de celle de la paroi périphérique, de sorte que lorsque
le dispositif d'agitation est entraîné en rotation autour dudit axe central par l'intermédiaire
du fluide contenu dans ledit récipient, le mélange et la turbulence résultants sont
tels qu'ils minimisent le déplacement radial d'une particule quelconque d'un tel fluide
par le dispositif d'agitation, par comparaison aux déplacements perpendiculaires à
un rayon à travers une telle particule par rapport audit axe, ledit récipient comportant
une ouverture d'orifice d'entrée dans le récipient et un orifice de sortie depuis
le récipient, l'un desdits orifices étant disposé sensiblement sur ledit axe et l'autre
desdits orifices étant disposé à la périphérie du récipient, d'où il résulte qu'en
fonctionnement, l'agitateur étant entraîné en rotation autour dudit axe, le fluide
s'écoulant depuis un premier dit orifice vers l'autre, est amené à suivre un trajet
en spirale, autour dudit axe, dans le récipient.
2. Dispositif de mélange selon la revendication 1, dans lequel chaque barre est de forme
constante en section transversale perpendiculaire au rayon respectif.
3. Dispositif de mélange selon l'une quelconque des revendications précédentes, dans
lequel ladite sortie est disposée sur l'axe du récipient et ladite entrée est disposée
à la périphérie du récipient.
4. Dispositif de mélange selon la revendication 3, dans lequel ledit récipient comporte
au moins une autre entrée dans ladite paroi d'extrémité à une position intermédiaire
entre ledit axe et la périphérie du récipient.
5. Dispositif de mélange selon l'une quelconque des revendications précédentes, dans
lequel ledit récipient est un récipient fermé comportant des parois d'extrémité opposées
perpendiculaires audit axe et une paroi périphérique cylindrique s'étendant entre
lesdites parois d'extrémité.
6. Appareil destiné à traiter une émulsion photographique comprenant un dispositif de
mélange selon l'une quelconque des revendications 1 à 6, comportant une première entrée
supplémentaire ou un groupement d'entrées dans une dite paroi d'extrémité et une seconde
entrée supplémentaire ou un groupement d'entrées dans une dite paroi d'extrémité,
un moyen destiné à fournir à ladite entrée à la périphérie du récipient un fluide
comprenant des "germes" de grains d'halogénures d'argent, un moyen destiné à fournir
à ladite première entrée supplémentaire ou groupement d'entrées un composant de fluide
comprenant une solution d'halogénures solubles, et un moyen destiné à fournir à ladite
seconde entrée supplémentaire ou groupement d'entrées un composant de fluide comprenant
du nitrate d'argent.
7. Dispositif de mélange selon la revendication 6, dans lequel ledit moyen d'alimentation
desdites première et seconde entrées supplémentaires comprend un moyen de distribution
d'écoulement à masse constante.
8. Dispositif de mélange selon l'une quelconque des revendications précédentes, comprenant
une chambre d'air, un moyen destiné à maintenir la température à l'intérieur de ladite
chambre d'air à une valeur prédéterminée, ledit dispositif de mélange étant disposé
à l'intérieur de ladite chambre d'air, d'où il résulte que la température du fluide
ou des fluides à l'intérieur du récipient est maintenue de façon correspondante.