Note: Descriptions are shown in the official language in which they were submitted.
CA 02293689 1999-10-22
Device for solubilizinQ a_pulverulent substance
The invention relates to a device for continu-
ously solubilizing a pulverulent substance which is
difficult to wet in a liquid, having a feed device for
the pulverulent substance and having a dispersing device
which is connected downstream of the feed device.
Devices of this nature, which can be used to
place pulverulent substances which are difficult to
solubilize, such as for example thickeners and stabiliz-
ers, in a colloidal solution or dispersion, are known in
principle. The standard systems used usually mean that
the dry substances have to pass through the dispersing
device a number of times in batches, and consequently
their structure may be subjected to considerable stresses
and even destroyed.
In addition, the prior art includes continuously
operating devices which, in a continuous passage, wet or
solubilize the pulverulent substances, but in this case
pulverulent substances agglomerate at parts which come
into contact, with them, thus interrupting the production
process.
The invention is based on the object of providing
a device for the continuous solubilizing of a pulverulent
substance which is difficult to wet in a liquid, by means
of which, in a simple manner, it is possible to operate
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continuously without any agglomeration at areas which
come into contact with powder, while simultaneously
achieving reliable wetting and solubilizing of each
individual powder particle.
This object is achieved in accordance with the
defining part of claim 1. The invention has the advantage
that the pulverulent substance is prevented from agglo-
merating in areas which come into contact with powder, in
particular in the outlet area of the feed device, in the
area in which it is sucked in, in the area/of contact
between powder and liquid or in the dispersing chamber,
where otherwise initial contact with the liquid presents
_. a risk of the powder sticking together and agglomerating.
In this way, it is possible to operate continuously, or
if desired in batches, without problems over an unlimited
period. This prolongs the service life and means that it
is no longer necessary to carry out cleaning work at
regular, short intervals.
It is expedient for the outlet of the preliminary
wetting unit to be guided tangentially into the disper-
sing unit, since the resultant "turbulence" (radial flow)
of the mixture entering the device avoids back-pressure
and promotes the removal of the product.
A preferred refinement of the invention consists
in the injector being provided with an adjustable nozzle
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in order to set different concentrations. This has the
further advantage that the nozzle can initially be closed
when liquid begins to be fed in, thus preventing blow-
back of the liquid into the outlet of the feed device and
avoiding the risk of agglomeration of powder.
In principle, in certain powders it is expedient,
in order to achieve a maximum concentration, for the feed
device to be arranged directly above the injector. On the
other hand, in many applications it may be advantageous
for the outlet of the feed device to be arranged below
the inlet of the preliminary wetting unit and for a hose
connection to be provided between them.
Very good results are achieved if the axis of
rotation of the dispersing device is horizontally ori-
ented and the longitudinal axis of the preliminary
wetting unit runs vertically, the outlet of the prelimi-
nary wetting unit opening vertically into the dispersing
device. However, in principle the device also operates
satisfactorily if the axis of rotation of the dispersing
device is vertically oriented and the longitudinal axis
of the preliminary wetting unit is horizontally or
vertically oriented.
A preferred refinement of the invention consists
in a pump being connected downstream of the dispersing
device. Particularly in the case of high-viscosity
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products, this arrangement ensures that the product is
removed in a particularly reliable manner. Moreover,
blow-back of the liquid into the injector, resulting in
blockage caused by swelling powder, is prevented in this
way. Furthermore, the additional sucking action of the
pump further increases the concentration. If a rotor with
a pump action is present in the dispersing device, this
rotor can be dispensed with under certain circumstances.
Anbther advantageous refinement of the invention
consists in providing the dispersing device with at least
one inlet for supplying diluting liquid and/or steam. In
this way, it is possible to carry out continuous dilution
,._or setting to the desired product concentration. The
supply of steam makes it possible to heat the solution in
the dispersing device.
The invention is described in more detail below
with reference to an exemplary embodiment which is
illustrated in the drawing. The only figure diagram-
matically depicts a cross section through the device
according to the invention.
Via a funnel-shaped feed device 10, a pulverulent
substance which is difficult to wet, for example a
thickener such as xanthan, is sucked into a preliminary
wetting unit 11 and, from there, passes into a dispersing
device 12. In the example illustrated, an outlet 16 of
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the feed unit 10 is located below and next to an inlet 17
of the preliminary wetting unit 11. As an alternative,
the outlet 16 may, for example, also be arranged next to
or above the inlet 17. The connection between the two is
produced by means of a hose connection 18. As an alter-
native to the feed unit 10 illustrated, it is also
possible to provide an automatic suction device.
The preliminary wetting unit 11 comprises an
injector 13 with an adjustable nozzle 15. A pressurized
liquid is introduced into the chamber of the injector via
a radial feed opening 20. Due to the suction pressure
which is generated, the liquid which flows out of the
injector 13 via the nozzle 15 entrains the pulverulent
substance, resulting in intensive wetting of the powder
particles.
The outlet 14 of the preliminary wetting unit
opens tangentially into the dispersing device 12, which
is of cylindrical design. In the example illustrated, the
dispersing device comprises a mixing chamber 23 with a
rotor 22, comprising one or more gear rings 24 and
internal pump vane 27, as well as a stator 28. The stator
28 comprises one or more gear rings. The gear rings of
the rotor and of the stator are arranged concentrically
inside one another. The product is forced to pass through
the shearing system. As an alternative to the toothed
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rotor/stator system, it is also possible to use a system
of deflecting surfaces (stator and/or rotor deflecting
surfaces) or any other dispersing system (not shown). Via
an outlet connection piece 25, the dispersed solution is
guided out of the mincing chamber 23 in a tangential
direction.
In addition, a diluting liquid and/or steam for
heating the solution may be supplied at a further inlet
26.
In the example illustrated, the axis of rotation
21 of the pump wheel 22 is arranged horizontally and the
longitudinal axis of the preliminary wetting unit 11 is
,.,arranged vertically.
