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Патент USA US2129864

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Patented Sept. 13, 1938
2,129,864
UNITED STATES PATENT OFFICE
2,129,364
PROCESS OF CRYSTALLIZING DEXTROSE
William B. Newkirk, Western Springs, Ill., as
signor, by mesne assignments, to Corn Prod
ucts Refining Company, New York, N. Y., a
corporation of New Jersey
Application .finie 4, i931, serial No. 146,421
(Cl. 1,27-62)
This invention relates to the production of high
purity dextrose from starch converted solutions
in which the sugar from one crystallizing opera
-tion is melted and re-used in another crystalliz
ing operation; the invention being concerned
`more particularly with a process in which the
cuite from the second crystallizer is delivered
to the second centrifugals K by means of which
the major portion of the mother liquor (hydrol)
is extracted, that is, such part of ' the mother
liquor as can be removed conveniently by cen
trifugal force alone.
converter liquor is given repeated crystallizations
'I'he steps as above described are known and
and the sugar produced at a later crystallizing
stage or stages is used after melting, at an earlier
the operating data required forpracticing them
crystallizing stage.
Y The object of the invention is to facilitate the
process and improve the purity and crystalline
character of the ultimate product by a proce
dure which reduces to a minimum the quantity
of impurities, that is, residual mother liquor, re
introduced into the process through the return
and re-use of the melted sugar.
The invention will be described in connection
with a “two-boiling” process in which the second
sugar is melted and used for a first sugar crystal
lization. Obviously the same improvement could
be applied to a process involving three or more
crystallizations in which the sugar at any late
stage of crystallization is re-introduced, in a
26 melted or dissolved state, into the process at an
earlier crystallizing stage.
The invention is illustrated in the accompany
ing iiow sheet which shows the improvement as
applied to a two-stage crystallizing process.
Referring to the drawing, A designates the
30
converter in which the starch in suspension in
acidulated water is converted to form the usual
dextrose solution. The dextrose solution thus
made is subjected to a series of treatments, i. e.,
35 neutralization, refinement, concentration and
cooling, indicated at B before being introduced
into the first crystallizer C. The massecuite from
crystallizer C is introduced into one or more cen
trifugal machines, indicated at D, by means of
40 which the major portion of the mother liquor is
extracted from the crystals and the residual im
purities washed out of the~crystals with fresh
water introduced at E; the first greens (the major
portion of the mother liquor) passing out of the
45 centrifugal machine into pipe F and the wash
water being discharged into pipe G. The washed
sugar is the finished product of the process and
will have a purity between 99.5% and 100%.
The ñrst greens are then given certain treat
ments at H. They may be re-converted and
then refined, concentrated and cooled. The re
conversion step, however, may be omitted. After
these pre-treatments the first greens are intro
duced into the second crystallizer J and crystalli
- zation eiïected in the usual manner. The masse
need not be here given. It has been the prac
tice to melt the second sugar, the sugar from 10
the centrifugals K without giving it the fresh
water to which the crystal masses in the first
centriiugals D are subjected. The reason for
this has been that washing with fresh water in
volves dissolving a considerable quantity of sugar 15
which, in the case of second sugar. would mean
a sugar loss which would be quite considerable
because of the relatively low purity of purged
but unwashed second sugar, the usual second
sugar purities being between 90% and 94%, dry 20
substance basis. If second sugar were washed
in the same way that iìrst sugar is washed, the
sugar content of the wash water would have been
so high as to entail a serious loss, while- the im
purity content would have made the wash water
practically unusable in the process.
It has been customary, therefore, to run the
second sugar, purged but unwashed, to a melter,
shown at L on the iiow sheet, where the sugar
is melted with Wash water from the first cen 30
trifugal D, conducted to the melter through pipe
G. The sugar melted at D passes through pipe
M back to the process at B where it was mixed
with
however,
converter
according
liquortofrom
former
the converter
methods A.
involved
35
returning to the process a considerable quantity
of impurities, as has been stated, which either
reduced the purity of the ultimate product, the
ñrst sugar, or involved more Washing than would
otherwise be necessary. Washing is undesirable, 40
first because of the loss of sugar which it entails,
and second, because of erosion which detrimen
tally ai'fects the brilliancy and luster of the sugar.
According to the present invention, the re
sidual hydrol in Vthe second sugar is displaced at 45
the end of the centrifuging operation by a dex
trose syrup consisting principally of dextrose and
water, which is introduced into the centrifugal
machine after the major portion of the hydrol
has been removed, and is forced through the
crystal mass by centrifugal action. Preferably
this dextrose syrup consists of wash water from
the washing of the first sugar which, as shown
on the flow sheet, is introduced into the second 5A
2
2,129,864
centrifugal by 'a pipe N shown as a branch of
the Wash water pipe G.
The wash liquor used in this connection is a
saturated dextrose solution, or approximately so,
Lì so that it is not capable of dissolving any consider
able amount of the second sugar. Its gravity and
viscosity are approximately those of the hydrol
in the second sugar. Thus, when introduced into
the second centrifugal K, this liquor will displace
the .residual hydr l on the faces of the sugar
crystals and force the same out oi' the sugar mass
into the hydrol outlet O. As a result of the ex
pedient the purity of the second sugar, which
is to be melted and returned to the first crystal
15 lization, due to the fact that the wash water has a
higher purity than the hydrol which it disp/laces,
may be increased to 97% or 98% which means
the elimination from the system of an appreciable
amount of impurities without any substantial loss
20 of sugar substance.
The invention has been described in a preferred
embodiment which, however, is to be considered
as typical and informative and not limiting the
application of the invention to the particular
25 process described. The intention is to cover all
equivalents as well as all modifications within the
scope of the appended claims.
I claim:
l. Process for the production of crystalline
30 dextrose which comprises: crystallizing a dextrose
solution and removing the mother liquor from the
crystals; subjecting the mother liquor to a crys
tallizing operation; centrifuging the massecuite
to remove most of its mother liquor; introducing
into the centrifugal machine, as a wash liquor
for removing residual mother liquor, a substan
tialiy saturated dextrose solution of higher purity
than the residual mother liquor to displace said
mother liquor and thereby increase the purity of
40 the sugar mass without substantial loss of sugar
in the wash liquor; and melting the dextrose from
the last named crystallizing operation and re
using the same, mixed with fresh dextrose solu
tion, for another crystallizing operation as the
process is continued.
2. Process for the production of crystalline
dextrose which comprises: crystallizing a dextrose
solution; centrifuging the massecuite to remove
most of the mother liquor; introducing a wash
liquid into the centrifugal machine to remove re
sidual mother liquor; subjecting the first named
mother liquor to a crystallizing operation; cen
trifuging this massecuite to remove most of its
mother liquor; introducing into the centrifugal
machine. for removal of residual mother liquor
therefrom, wash liquid from the first centrifuging
operation; and melting the dextrose from the
second crystallizing operation and re-using the
same, mixed with fresh dextrose solution, for an
other crystallizing operation as the process is con
tinued.
20
3. Process for the production of crystalline
dextrose which comprises: crystallizing a dextrose
solution; centrifuging the massecuite to receive
most of the mother liquor; introducing into the
centrifugal machine fresh water to remove the 25
residual impurities; subjecting the mother liquor
from the first named crystallization to a second
crystallizing operation; centrifuging this masse
cuite to remove most of its mother liquor; intro
ducing into the centrifugal machine liquid from 80
the fresh water washing operation in the ñrst
centrifuging operation, which is substantially
supersaturated as to dextrose and has a higher
purity than the residual mother liquor of the
second massecuite, to displace said residual
mother liquor; and melting the dextrose from
the second centrifuging operation and using the
same, mixed with fresh dextrose solution, for an
other crystallizing operation as the process is
continued.
WILLIAM B. NEWKIRK.
CERTIFICATE OF CORRECTION.
Patent No. 2,129,86L».
'
WILLIAM B. NE/JKIRK.
september 13, 1958 .
It is hereby certified that error appears in the printed specification
of the above numbered patent requiring correction as follows: Page 2, second
column, line 25, claim 5, for the word “receive” read remove; and that the
said Letters Patent shouldbe read with this correction therein that the
same may conform to the record of the case in the Patent Office.
Signed and sealed this 25th day of October, A. D. 1958.
Henry Van Arsdale
(Seal)
Acting Commissioner of Patents.
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