Note: Descriptions are shown in the official language in which they were submitted.
2000846
A METHOD AND AN ARRANGENENT FOR THE CONTINUOUS DILUTING OF A
CONCENTRATED SOLUTION
The present invention relates to a method for the
continuous diluting of a concentrated solution by means of a
continuous flow of diluting liquid. The invention also
relates to an arrangement intended for the same.
Concentrated solutions of different types occur in many
different ~ranches of industry and the handling of these
concentrated solutions always involves problems and risks of
material damage and personal injuries. When the concentrated
solutions have been used in production, a portion of the
solutions can be drawn off via a drain and be dealt with in a
conventional purifying works, if prior to drawing off they
have been diluted to a very ~ow concentration. Other
solutions are not suitable for drawing off via a drain, but
they may become easier and safer to handle after dilution.
The diluting of concentrated solutions in batches is space-
demanding as large mixing tanks are required.
In the industry where liquid foodstuffs are filled intonon-returnable packages of an aseptic type hydrogen peroxide,
~22, is used as a sterilizing agent. This peroxide occurs
in concentrations of 30 - 50 per cent by weight in the
production.
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20U0846
on a packing machine where the moving packin~ material
web of plastic-coated paper passes through a peroxide bath
for sterilization, a bath with at least 30 liters of peroxide
solution is used. After approx. one week's production the
peroxide bath has been polluted by particles from the packing
material and with increased pollution the concentration of
peroxide diminishes and the bath bacomes unusable for
sterilization.
When the peroxide solution has to be changed it may be
drawn off either directly into the drain or onto the floor,
which, above all owing to the vapors formed by this peroxide,
is harmful to machine operators and any personnel present on
the premises. Peroxide vapor which is inhaled exerts a
corrosive action on mucous membranes, and direct contact with
peroxide corrodes skin and clothes. Alternatively the
peroxide solution can be pumped over to kegs or drums for
subsequent destruction. Such handling too may involve
hazards to those handling the solution.
It is an object of the present invention to deal with
concentrated solutions in a simple manner demanding little
space and dilute them so as to minimize the risk of personal
in~uries.
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2000~46
It is a further object of the 'present invention ~o
provide an arrangement for the continuous dilution of
concentrated solutions.
These and other objects have been achieved in accordance
with the invention in that the method of the type described
in the introduction has been given the characteristic that
the concentrated solution is fed continuously in small
quantities to the diluting liquid owing to a small quantity
being diverted from the inflowing diluting liquid and being
fed to the concentrated solution, the amount of concentrated
solution fed to the diluting liquid being of equal magnitude
as the quantity of diluting liquid fed to the concentrated
solution.
The invention will now be described in more detail with
reference to the attached drawings, wherein
Fig. l shows schematically a preferred embodiment of the
invention,
Fig. 2 shows a further preferred embodiment of the invention.
The arrangement in Figure 1 consists of a substantially
closed main tank 1 holding at least the quantity of
concentrated solution which is to be diluted. There must
also be space for possible vapor formation. In this main
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tank 1 is enclosed a small partial tank 2 intended for the
diluting liquid. The main tank and the partial tank 2 are
connected with one another on the one hand via an air gap 3
for vapors discharged in the upper part of the tanks, on the
other hand via an overflow pipe 4, preferably placed
vertically with its bottom end immerse`d in the main tank 1
below the lower boundary surface of the partial tank 2. The
top end of the o~-erflow pipe 4 is on a level with the level
of the concentrated solution in the main tank 1.
In the upper part of the partial tank 2 opens up a feed
pipe S for diluting liquid. This feed pipe 5 is forked so
that a small amount of diluting liquid is diverted from the
feed flow and is supplied to the main tank 1.
The main tank 1 is provided with an openable drainage
line 6 suitably placed at the bottom 7. The bottom 7 may be
made sloping with the drainage line 6 being in the upper
part. Hence, on changing of the concentrated solution which
is to be diluted, a certain amount of diluting liquid will be
allowed to remain in the tank 1. This amount of liquid
contributes to an immediate dilution.
The outlet line 8 of the partial tank 2 is constituted
of an overflow pipe whose one and opens below the liquid
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20008~6
surface in the partial tank 2. The arrangement is provided,
moreover, with a ventilating pipe 9 for the discharge of
vapors and for reducing the danger of excess pressure in the
tanks.
The concentrated solution whic:h is to be diluted is fed
to the main tank 1, where it occupies almost the whole space.
The supply of the concentrated solution to the main tank 1
should be arranged in a safe manner so that the solution does
not need to be handled manually. The upper part of the
arrangement might then be filled with vapors which are
discharged via a ventilating pipe 9 which may be connected to
the central ventilation and conducted away from the
production premises.
The diluting liquid, which e.g. may be water, is
supplied to the arrangement through an inlet line 5. In the
event of the arrangement being used on aseptic packing
machines, the waste water from the water ring compressor of
the machine, which is used for scrubbing the air containing
hydrogen peroxide circulating in the machine can serve
excellently as diluting liquid. The greater part of the
diluting liquid supplied is fed to the partial tank 2. A
small amount is branched off and is fed to the main tank 1.
The liquid level in the main tank 1 rises and thus also the
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2000~6
level in the overflow pipe 4 which connects the main tank 1
to the partial tank 2. A small quantity of concentrated
solution, corresponding to the diluting liquid fed to the
main tank 1, passes via the overflow pipe 4 out into the
diluting liquid of the partial tank 2.
The partial tank 2 is drained continuously via its
outlet 8 which is constituted of an overflow pipe, This
overflow pipe 8 opens below the liquid surface, so that the
vapors should not be aole to pass this way. If the diluted
solution is allowed to be drawn off directly into the drain,
the outlet 8 c~n be connected directly to this. Otherwise an
appropriate arrangement is present to take charge of the
liquid after the outlet pipe 8.
A small portion of diluting liquid is fed continuously
into the main tank 1 at the same time as the concentrated
solution passes via the overflow pipe 4 out into the partial
tank 2. This small quantity of diluting liquid thus will
gradually cause the contents of the main tank 1 too to be
diluted to a harmless concentration. By keeping constant the
diluting liquid fed to the concentrated solution it is
possible to control the dilution process and calculate the
ultimate concentration. The diluting liquid can be kept
constant, for example, be giving the branch line 10 from the
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inlet line 5 of diluting liquid a certain dimension or, as is
shown in Fig. 2, by providing a vessel with constant water
head and a bottom outlet opening of a defined dimension at
the inlet 5 of the diluting liquid.
With a main tank of 50 liter and with an inflow and
outflow of 3.7 liter per minute it takes approx. 20 hours
until the concentrated solution in the main tank 1 too has
been diluted to a concentration of below 1 per cent by
weight, when the peroxide may ba considered harmless and be
drawn off into the drain. With other ~uantities and other
inlet and outlet flows respectively other diluting times are
obtained in corresponding manner.
After the time which is required for the desired
dilution of the content of the main tank 1, the openable
draining line 6 may be opened and the main tank 1 emptied.
The main tank 1 now is ready to accept a new quantity of
concentrated solution and the diluting process is repeated.
As is evident from the aforegoing description a method
and an arrangement are provided by means of the present
invention for the continuous diluting of a concentrated
solution without any risk of`personal injures and where the
procedure can take place in a wholly enclosed manner, since
no manual handling is required before the solution has been
diluted to a harmless concentration which can be easily
handled.
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