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Патент USA US2119182

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31, 1938.
'1
P._ SCHUFTAN ET AL -
2,119,182
METHOD A’ND APPARATUS FOR CONDENSING LIQUIDS BY FREEZING
Filed Feb. s, 1936
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INVENTOR
Paul-2f
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I Patented ‘May 31,
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UNITED‘ I STATES PAT EN OFFICE
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1 ‘2,119,182
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METHOD AND APPARATUS ron CONDENS-V
me LIQUIDS BY FREEZING
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Paul Schuftan, ‘Hollriegelskreuth, ‘near Munich,
and Hans Ranke, Solln, near Munich, _Ger
many
:Appllcation February 3, 193b, Serial No; 62,214
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In Germany February 18, 1935
10 Claims.
(01. 62-124) '
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in' which w is the mean velocity of the liquid, 6
is the diameter of the conduit or vesselin which ,'
the motion occurs, and 'y ‘is the kinetic viscosity
(viscosity per unit mass) of the liquid (see Der
In the commercial application of known proc
esses for condensing liquids, such as salt solutions,
milk, fruit juices and the like ‘by freezing out
' water, di?iculties are encountered particularly in
'Chemie-Ingenieur‘, Eucken Jakob, Vol. 1, part 1;
‘ 5 that when/the liquid is ‘agitated in contactwith
‘ the cooling surfaces for the ‘purpose of securing
page 26 and following) .
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The solution ‘to be condensed may be degasi
a: su?iciently rapid-heat transfer to permit‘ the
by any of ‘the known methods and the ex
treatment of a'suitable volume-of liquid in an h?ed
of air from the solution during its treat
apparatus of 'a'given size, the ice crystallizes out ' clusion
may be accomplished very simply by, e. g.
10 in such ?nely divided form that-its separation‘ ment
closing' the freezing vessel and'completely filling
from the concentrated liquid is dii?cult and in
it
with the solution and. discharging the icev
c?icient. This is particularly true when the coné
densing process is ‘applied to an already rela ' through a'pipe in'such away that it provides a
tively concentrated'liquid. Moreover, in spite of seal against access of air to the solution.
The invention will be described in. detail in‘ 15
-l5 vigorous movement of the liquid in contact with connection
with the condensation-of milk in the
' the cooling surfaces, the heat transfer rate is not’ ‘ apparatus illustrated
in the accompanying draw- ’
, as great as might be expected.‘
A It has been found that the process is, greatly
ing. -Referring to the drawing, the apparatus
2o’ improved with respect to both the heat transfer
rate and the formation and separation of ice‘
crystals by freeing the solution from gas and
preventing the admission of‘ air or other gas to
the solution during its treatment. The reason
comprises a cooling vessel I provided with the
cooling jacket 4. The refrigerant, e. g.-/brine or 20
a gaseous cooling agent, is circulated between the
outerwall of‘ the vessel l and the jacket 4 and
is caused to move spirally in_ said space by the
spirally arranged‘ vane 8 and when brine or other
A N for the results obtained by the exclusion of gas
liquid is used as the cooling agent it is- caused
to move at such a speed that the critical vReynolds
number is exceeded and its movement ‘is tur
25 from the solution may be that otherwise the gas
dissolved‘ in the'solution exceeds the solubility
limit due 'to the concentration of the solution and
separates‘ due'to the agitation of the solution inv
30 the form of fine bubbles or films which interfere
bulent. Within the freezing vessel I is the dis- .
placement member 2 whichis mounted on’a ver
30
with the heat transfer and withthe growth of _ tical axis to be rotated by suitable driving means.
’ ‘larger crystals. As)" stated, it has been found The displacement member 2 carries the agitator ‘
‘that when gas is carefully excluded from the 'solu - members 3 which, serve to intensively agitate the
'tion\ during the condensing-treatment, not only
‘ milk in the annular space between the wall of
the heat transfer from the solution to the cooling ' vessel l and the cylindrical displacement mem- ‘ 3535 surfaces is greatly'improved, but large grained her 2. _ In operation the vessel, is ?lled with
crystals are formed which are readily separated. ' liquid, e. g. milk, through the'pipe controlled by
Furthermore the movement of the liquid may be the valve 5 up to the top of thecone ‘Ivor even
increased to an extent which otherwise would re- , higher into the tube 6 so that the upper surface‘
suit in objectionable foaming and this’ increased of the liquid, is unaffected by the agitator and 40
' 4'0 ‘movement of the liquid further improves the heat remains quiet and thus any mixing of the liquid
transfer. _It has been foundthat the rate of heat with air or gas entering through the discharge _
transfer may be increased from 10 tov 100 times tube 6 is avoided. ' If necessary-the entrance of
without, objectionable foaming or any di?lculty in - air through the tube 6 to contact withthe agl-,
the separation of ice from the concentrated liquid. tated- liquid may be prevented by the use of a 45
[45 For a. full utilization of the highheattransfer - U-tube or liquid seal.
The operation of the process is such that the
rates'attainable, the brine'used ‘for cooling the
heat‘transfer ‘surfaces is circulated at such a liquid, e. g. milk, is continuously supplied to the ‘
high rate of speed in contact with said surfaces vessel and ice mush is continuously discharged '
r50 that the critical Reynolds number is‘ exceeded
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_ through the cone 1 and tube 6.‘
the
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equation
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milk and the temperature of the cooling wall are
and the’ movement‘of'the cooling brine is tur
_ bulent. The Reynolds num‘ r, Re, is defined by
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so adjusted that‘the formation of an adhering
layer of ice on the wall of vessel l is avoided and on the other hand the ice mush collecting in the
cone 1 is of such a consis my that it will flow
2
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2,119,182
or may be forced without excessive consumption
of power out through the tube 6.
By the use of the displacement body 2 the
shall be as vigorous as possible and in any event
turbulent.
We claim:
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volume of liquid under treatment is reduced with
1. In processes of condensing liquids involving
respect to’the area of the cooling surface and the - moving a liquid in contact with a cooling sur
rate ofa?ow of the liquid through the freezing face and separating the resulting ice crystals
space is increased. The cooling of the liquid may from mother liquor, the improvement which con
be intensi?ed by making the surface of the dis
sists in making the movement of the liquid in
placement body also a cooling surface.
contact with the cooling. surface turbulent, pre
,With highly viscous solutions, if the discharge venting the presence of emulsi?ed gas in the liq 10
of the ice mush should be dii?cult or requireex , uid during its movement in contact with the cool
, cessive pressure, its discharge may be facilitated ' ing surface and adjusting the rate of movement
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/ by a screw- or propeller agitator arranged abo’ve
the displacement member 2 or by replacing the
15 conical member 1 by a pipe connected tangen-,
of the liquid and the temperature of the cooling
surface so as to prevent the formation of an
adhering layer of‘ ice on the cooling surface.
15
tially to the top of the freezing vessel.
2. Process as‘ de?ned in claim 1 in which the
The ice mush produced may be delivered into ‘liquid is degasi?ed prior to its contact with the
a centrifuge in-which the concentrated liquid
and the ice crystals are separated and the con
centrate may be subjected to a repetition of the
condensing operation under suitable conditions
depending on its characteristics.
The ?rst ap-v
plication of the condensing process to the liquid
generally may be carried outvwithout degasi?
cation, but when the mother liquor is to be re
treated it must be degasi?ed; otherwise the gases
liberated during, the ?rst application of the con
densing process will interfere with the transfer
cooling _surface.
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3. Process as de?ned in claim 1 in which con
tact of gas with the liquid while it is being agi 20
tated in contact with the cooling surface isv
avoided.
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4. Process as de?ned in claim 1 in which the
velocity of the liquid in contact with the cooling
surface is such that the critical Reynolds num'-. 25
bar is exceeded.
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5. Process as de?ned in claim 1 in which liquid
to be concentrated is mixed with already con
of heat and impair the quality of the ice pro- ' centrated liquid in such proportions that the de
30. duced. The degasi?cation may have to be re
sired ?nal concentration of the mixture may be 30
peated before each successive application of the
condensing process to the mother liquor. In
some -cases,_for instance, when the gas content
of the original liquid is high, it may be neces~
sary to degasify it before the ?rst application
of the condensing process. The degasi?cation
has been found tobe advantageous even in in
stances in which the presence of gas does not
result in the formation of foam.
An advantageous procedure in the condensa
40
tion of liquids to a high concentration which
otherwise would involve a number of. repetitions
of the condensing process‘on the mother liquor
is to mix a concentrate ‘of the desired ?nal con
45 centration with fresh solution in such, propor
accomplished by a single passage of the mixture
in contact with the cooling surface followed by
separation of ice crystals.
6. Apparatus for the concentration of solutions,
by freezing out solvent comprising a cylindrical
vessel, means for cooling the wall of said vessel,
means for forcing liquid into said vessel adjacent
the bottoin thereof, an over?ow pipe for the dis
charge of a mixture of ice and concentrate from
the vessel, said over?ow pipe forming a trap pre 40
venting access of air to the liquid in the vessel.
7. Apparatus for concentrating solutions by
freezing out solvent comprising a cylindrical ves
sel having'its longtudinal axis vertically disposed,
a cylindrical displacement member rotatably
tions that the resulting mixture can be brought _ mounted in said vessel with its surface concen
to the, desired ?nal concentration by a single
tric to the wall of said vessel, agitator members
application of the condensing process. ,.F'or this ' carried by said displacementmember in the an
purpose fresh solution entering through the pipe
nular space between the displacement member
and the wall of the vessel, means for rotating
liquor from aprevious treatment supplied through _\ said displacement member, means' for forcing 50
50 controlled by valve 5 may .be mixed with mother
. the pipe controlled by valve-I, _As will be-appar- ‘ ~ liquid into the lower-end of said vessel, and means“
ent, this procedure may be carried. on continu
for discharging fluid from the upper end of said
ously with a continuous supply of fresh solution,
a continuous withdrawal of, a portion of the con
centrate, and a continuousrecycling of a por
tion of theconcentrate. ,. .
The process herein described permits the re-.
vessel.
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8. Apparatus as de?ned 'in claim 7' in which 55
the means for discharging ?uid from the upper _
end vof _the vessel comprises a liquid seal.
9. Apparatus -as de?ned in claim 7 in which
moval of, for instance, more than one third of the means for discharging liquid from the (upper
00 the water content of milk in a single stage and end of the, vessel comprises a frusto-conical mem
the attainment of heat-transfer values of more ‘ ber the larger end of which ?ts the upper end
-than 5000 11K caL/mlh. C. The process is ca
of the vessel“
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bible of numerous variation} some of which have
been .described and suggested so‘ long as the es
“- sential features (1)" that no gas is liberated from
the liquid or absorbed in it during the agitation
and cooling thereof, and (2) that the motion of
the liquid in contact with the cooling surfaces
10. Apparatus as de?nedin claim '7 in which
the means for discharging liquid from the upper
end of the vessel comprises means for positively 05.
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moving ‘mush ice.
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PAUL
SCHUFYI‘AN.
HANS RANKE.
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‘ CERTIFICATE 0E CORRECTION.
Patent No. 2,119,152.
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- my 51, 195B.
PAUL so?uFmn, ‘ET AL. ‘
It iahereby cyertifi’ed' that errorjappodra' in‘the printed’ apecifiontion‘
of the above numbered patent requiring correction as follows: Page 2, second
column, line‘ 141,“ claim 6, after "vessel". and ‘before the {varied insert .and
‘means for agitating the‘ liquid within adid'ylesse'l'; and. that the oaid‘Letf 1
tors Patent ghouldbo read with this corroction therein that‘ the some, may
conform to tho‘ record'of the one‘ in the Potent 'orrice.“ .
Signed and sealed this 12th day of July, A-"D- 1938.
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lienry'van Aradale,‘
Ao?lhg commipaioner' of Patents’.
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