Improved Method for Cleansing or Whitening Sugar in the Centri- fugal Machine and Apparatus therefor.
Year: 1889

page_text: Date of Application, 8th Mar., 1889
Complete Specification Left, 7th Dec., 1889-Accepted, 11th Jan., 1890
PROVISIONAL SPECIFICATION.
Improved Method for Cleansing or Whitening Sugar in the Centri-
fugal Machine and Apparatus therefor.
I, FRIEDRICH DEMMIN of Königgrätzer 91, Berlin in the Empire of Germany,
Sugar manufacturers engineer, and Civil Engineer, do hereby declare the nature of
this invention to be as follows
The present invention relates to a method and corresponding apparatus for cleansing
or whitening the sugar in the centrifugal machine with the least possible quantity of
fresh liquor and in the least possible time.
The cleansing or whitening of the sugar in the centrifugal machine no matter
whether the sugar consisted of boiled filling-mass or of raw sugar mashed with
syrup has hitherto been effected by one of the following methods; either after the
removal of the green syrup a quantity of pure fine liquor was added sufficient to
properly whiten the sugar, in which case sometimes the liquor used for one process
was used for preliminary cleansing in the next before the pure liquor was used, or
steam was introduced in the centrifugal basket for the purpose of melting part of the
sugar and thus producing the liquor in the centrifugal machine itself, or combinations
of these two methods were used. With all the methods for cleansing known up to the
present time a great quantity of liquor (on the average from 30 to 50 per cent. of the
quantity of the sugar to be cleansed) has been used, and it has been proved that
the desired result could not be obtained with less liquor.
With the present invention the above mentioned result is obtained by collecting the
liquor discharged during the operation of the centrifugals separately and in different
parts so that these parts can be introduced again in the same succession into the
centrifugal basket during the next process or the treatment of the next quantity of
uncleansed sugar, and can thus be used over and over again. In this manner the
sugar in the-centrifugal is treated first with a liquor which is almost the same as that
adhering to the sugar crystals, then better and better liquors are introduced in and
discharged from the centrifugal the syrup or liquor adhering to the crystals becoming
purer and purer in consequence. At the end of the process a small quantity of pure
fine liquor is added and when this is discharged from the centrifugal the cleansing
process is finished. The same liquor can in this manner be used for a great number
of quantities of sugar to be treated.
The apparatus used for this purpose consists preferably of a drum or body formed
with a series of receptacles or chambers and which can be moved round a standard
which forms so to speak the plug of a cock and is formed with three passages or
channels which end at the top of the standard in three socket-branches.
These passages or channels are arranged in such a manner, that when two of them
lead to one of the chambers the third will lead to another.
The drum with its chambers may be moved round the standard forming its axis in
any suitable manner either by a hand wheel or any suitable gearing.
The apparatus is connected with a centrifugal machine in such a manner that the
socket piece of the passage leading to the chamber where only one passage ends is
connected by a tube with. the discharge chamber of the centrifugal, while the other
two socket pieces the passages of which lead into the same chamber are connected by
means of tubes one with the inlet opening of the centrifugal, the other with a suitable
compressed air apparatus. The tube of the latter connection is provided with a
stop-cock.
When the sugar to be treated is placed in the centrifugal basket and the green
syrup, supposing boiled filling mass to produce crystal granulated or other loaf or

page_text: cube sugar to have been used or the mash syrup if raw sugar mashed with syrup is
used, has been discharged and after the chambers of the drum are so adjusted that
that chamber containing the most impure liquor collected during the previous treat-
ment is in connection with the two passages, the stop-cock of the compressed air tube
is opened when the air will rush in and drive the liquor contained in the chamber
through the other passage and the tube connected therewith into the centrifugal
basket where it passes through the sugar and is discharged through a separate tube if
it is desired to keep it apart from the previously discharged green or mash syrup.
The drum with the chamber is now turned until the next chamber is in connection
with the two passages and the liquor contained in this will be driven into the centri-
fugal by the compressed air. The ordinary discharge pipes have been closed mean-
while so that the liquor discharged passes through the discharge pipe which is now
in connection with the first and now empty chamber of the drum. The drum is then
again turned to empty the third chamber into the centrifugal and the liquor discharged
is returned to the second chamber and so on until the last chamber which has
previously been filled through a suitable mechanism with pure fine liquor, is emptied
into the centrifugal and returned into the last chamber but one. The cleansing
process is now finished and it will be seen that the liquors discharged from the
centrifugal is stored in the chambers of the drum in gradually increasing purity and
is used again for the next process in the same succession in which they are
discharged from the centrifugal by beginning again with the first chamber and going
on until the last.
Instead of using pure fine liquor for the last stage of the process, steam might be
introduced into the centrifugal after the liquor of all the chambers of the drum has
been passed through the centrifugal basket and back into the chambers, and the pure
liquor be formed by the molten sugar itself, which liquor would be discharged into the
last chamber of the drum and be used as the purest part of the liquor contained in the
chambers during the next treatment.
The moving and registering mechanism of the drum may be of any suitable con-
struction for instance the standard may consist of a solid column and the plug of the
cock be replaced by two surfaces sliding on each other and formed with openings
which register corresponding to the chambers used. The apparatus may also be so con-
structed that the drum with the chambers is stationary and the standard forming the
plug of a cock is movable round its axis, or the apparatus may be constructed in such
a manner that the receptacle containing the chambers is adapted to slide along under
the part containing the socket piece, the whole being so arranged that one chamber
always is in connection with the outlet opening of the centrifugal and another chamber
with the inlet opening.
The apparatus may also be provided with a fourth passage which is connected with
a suitable apparatus for pumping the air after the chamber is filled, out of the chamber
and out of the liquor, it being often the case with heavy sugar that the syrup while
being discharged from the centrifugal takes up a quantity of air.
The liquor contained in the chambers of the drum may be fed to the centrifugal
by a suitable pumping device instead of compressed air, or the drum may be arranged
on a higher level than the centrifugal and enter into the latter by its own weight; in
this case a suitable pumping device is provided for pumping the discharged liquor
back into the empty chamber.
If, as is sometimes the case, the cleansing process is to be gone through at not too
low a temperature the liquor must be kept at the desired temperature. For this
purpose the outer casing of the centrifugal may be made double and in the space
between the two walls exhaust steam or hot water introduced through a suitable inlet
leaving it through a suitable outlet. The outer casing may moreover be coated
with a wooden casing or other non-conducting material.
If raw sugar mashed with syrup or sugar mass boiled in the vacuum pan to crystal
sugar is to be treated care must be taken that no fine sugar crystals pass with the
syrup or liquor through the sieves of the centrifugal basket so that the syrup which is

page_text: to be used over again does not become too thick in time and thus retard the process.
To avoid this passing of fine sugar crystals a combination sieve is preferably used
consisting of two or more ordinary finely perforated centrifugal sieves between which
is placed some suitable filtering material.
With the employment of this method only a part of the liquor equal to 5 to
15 per cent. of the sugar is used or taken up by the sugar because of the using over
again of the liquor, and the time taken up by this process is also shorter than with
any other.
Dated this 8th day of March 1880
COMPLETE SPECIFICATION.
Improved Method for Cleansing or Whitening Sugar in the Centri-
fugal Machine and Apparatus therefor.
I, FRIEDRICH DEMMIN of Koniggratzer Strasse 91, Berlin in the Empire of
Germany, Civil Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
The present invention relates to a method and corresponding apparatus for
cleansing or whitening the sugar in the centrifugal machine with the least possible
quantity of fresh liquor and in the least possible time.
The cleansing or whitening of the sugar in the centrifugal machine no matter.
whether the sugar consisted of boiled filling-mass or of raw sugar mashed with syrup
has hitherto been effected by one of the following methods; either after the removal of
the
green syrup a quantity of pure fine liquor was added sufficient to properly
whiten the sugar, in which case sometimes the liquor used for one process was used
for preliminary cleansing in the next before the pure liquor was used, or steam
was introduced in the centrifugal machine for the purpose of melting part of the sugar
and thus producing the liquor in the centrifugal machine itself, or combinations of
these two methods were used.
With all the methods for cleansing known up to the present time a great quantity
of liquor (in the average from 30 to 50 per cent. of the quantity of the sugar to be
cleansed) has been used and it has been proved that the desired result could not be
obtained with less liquor.
The desired result can be attained by the application of this invention in collecting
the pure liquor which is discharged from the mass of sugar treated in the centrifugal
machine in different parts or portions and separated from each other, so that in the
subsequent treatment and while the centrifugal machine is in motion it can be
conveyed again to the mass of sugar by means of air pressure or an ordinary
pump.
If the apparatus is provided with the requisite number of sections or chambers the
re-application of the pure liquor can be continued whereby a liquor is produced
identical in its condition to the syrup adhering to the sugar crystals in the centri-
fugal machine and after that the syrup conveyed to the centrifugal machine is of a
gradually improving quality and when precipitated through the mass of sugar therein,
the quality of the liquor adhering to the sugar crystals also becomes purer by
degrees.
Apparatus suitable for the before described operations is shown in the accompanying
drawings in which fig. 1 represents the general arrangements in connection with a
centrifugal machine of any usual construction, Figs. 2 and 3 are detail views of the
collecting vessel B provided with any desired number of chambers C which revolve
round the axis A and which serves as the distributing apparatus.

page_text: By this arrangement it is only necessary to revolve the collecting vessel round its
distributing axis to convey the liquor discharged from the centrifugal machine into
the chambers Cin order to collect the same there in the subsequent and separate order
in which it is again re-conveyed in the systematic improving quality to the mass of
sugar to be treated.
The collection takes place in the chambers when passing a section as for instance
when the apparatus fig. 3 is provided with chambers the liquor contained in chamber C
will, after having undergone its application in the centrifugal machine return to the
chambers C².
For this object the distributing axis A is provided with the channels ef g figs. 2
and 3 which are connected with the tubes hik these channels being so arranged that
when the channel e is in connection with one chamber C the channels and
communication with another chamber C.
gare in
The connection of the apparatus represented in figs. 2 and 3 with a centrifugal
machine of any construction is effected as shown in fig. 1 by connecting the
branch with the discharge end of the outlet chamber o of the centrifugal machine
which connection serves to effect a preliminary collection of the liquor discharged
from the centrifugal; the branch i connects the apparatus with the pipe p entering
the centrifugal machine while the branch connects the same with a compressed air
apparatus and is provided with the stop cock 9:
The working of the apparatus can be effected in the following manner;-When the
mass of sugar to be treated is placed in the centrifugal drum and operated upon by a
boited filling mass, the so-called green syrup, is separated from the treated mass and
drawn off by the discharge pipes connected with the outlet chamber o Fig. 1 and then
the connection of the chambers C in the collecting vessel B is so adjusted in relation
to the channels g and f that by opening the stop cock Fig. 1 the compressed air
enters the chambers C fig. 3 and forces the liquor contained in the same, (and which
is of an impure quality on account of being the remnant of a previous treatment)
first through the channel f Fig. 3 as indicated by the arrow in fig. 2 and afterwards
through the pipe p fig. 1 into the centrifugal machine. The syrup precipitated
through the mass of sugar and discharged from the centrifugal machine may be
carried off from the outlet chamber o fig. 1 by the discharge pipe if it is desirable
to keep the same apart from the previously discharged green or mash syrup.
The collecting vessel B is then sufficiently moved round the distributor A to
connect the channels g and f with the chamber C' as shown in fig. 3 whereby when
the channel e is brought in connection with the chamber by opening the stop
cork Fig. 1 the liquor contained in chamber is forced into the centrifugal
machine.
In the meantime the discharge pipes s and of the outlet chamber o fig. 1 are
closed with the effect that the liquor which is precipitated through the branchi
Fig. 1 into the channel e passes to the chamber fig. 3 in the collecting vessel
where it remains for re-application at the next operation.
The said vessel B is then turned to connect the channels and with the
chambers C² the liquor contained in the chamber (being forced into the centrifugal
and subsequently entering the outlet chamber o to return by means of the channel e
into the chamber (.
This process is continued until the turn in the series comes to chamber ( into
which the pure liquor can be conveyed by means of a charging cock or the like
attached to the same.
The pure liquor applied to work the mass of sugar in the centrifugal machine is
subsequently collected in the chamber C and furnishes at the next operation the
liquor applied at the last series of operations. At the conclusion of these operations
the discharged liquor according to the number of chambers C used is collected again
into the collecting vessel in separate parts in the same order as it left the centrifugal
and corresponding with the degree of purity of the same.
The next operation is as already. described.commenced at..the..chamber Cland is

page_text: followed on to the chamber which system secures the re-conveyance of the liquor
into the centrifugal machine in the same order of rotation as it was discharged there-
from and by this arrangement the gradually improving liquors succeed the first
and most impure quality the last part entering the centrifugal being of the purest
quality.
Steam can be applied in place of the liquor produced in the known process and
after the liquor in the collecting vessel B has been worked through the centrifugal
machine and returned to B the steam is then conveyed on to the mass of sugar in
the centrifugal machine and the pure liquor which results from this operation enters
subsequently into the chamber CZ and is applied again as the last portion at the next
operation as being of the purest quality.
The collecting vessel B can be moved round by any suitable means such as those
shown in fig. 2 where a wheel m is attached to it so that the vessel B can be turned
round its axis by hand or as shown in fig. 1 the vessel may be provided with a toothed
ring upon its circumference which is connected with the hand wheel n.
The collecting vessel B is provided with any desired number of chambers C and
the distributing apparatus can as regards its construction be arranged in any con-
venient manner. As an example another arrangement of this distributing apparatus
is shown in fig. 4 where the revolvable vessel B is provided with plates A at its
upper and lower sides and these plates have ports or openings which are adapted
to register or come opposite the ports or openings in the stationary parts of the
distributing apparatus in the manner shown in fig. 4.
The apparatus can further be so arranged that the collecting vessel instead of
revolving round an axis will slide upon rails in a horizontal or vertical direction
whereby the chambers C placed in a straight and corresponding line may be moved
under the distributing apparatus this will allow of several regulating contrivances
being applied if necessary.
As illustrated in fig. 3 a fourth channel 6 may be applied in connection with an air
chamber to absorb the air with which the liquor in the chamber has been impreg-
nated while operating upon the mass of sugar in the centrifugal machine or
this channel may be applied to draw the liquor used in the centrifugal into the
chambers C.
The liquors collected in the vessel B are separated from one another and when
discharged from the centrifugal machine can be re-conveyed into the latter not
only by means of air pressure as already described but also by the application of a
pump. The same result may also be effected by placing the collecting vessel upon a
higher level than that of the centrifugal machine but in this case a pump would be
required to re-convey the syrup discharged from the centrifugal machine into the
collecting vessel.
With the object of carrying out this operation one or more collecting vessels B can
be employed in connection with one centrifrugal machine; or several centrifugal
machines may be connected with one collecting vessel.
By the treatment of inferior qualities of masses of sugar and where the liquor is
repeatedly applied to act as the purifier it may become necessary that the said
liquor being rendered more impure after every application should be kept in this
condition and so re-applied upon the mass of sugar but in this case it will be
necessary to raise the temperature of the impure liquor to the requisite degree to
render. the same serviceable again.
Another impediment to the re-application of impure liquor consists in its tendency
to carry off the small sugar crystals while operatiug upon the mass of sugar in the
centrifugal machine and to convey them through the orifices of the centrifugal sieve
and convert the liquor into a thick paste-like substance.
When by the working of this contrivance steam is conveyed into the centrifugal
machine or into its encasing shell the liquor is kept at the effective temperature
but the application of steam.is. not always desirable and even not admissible if a
solution of the sugar or the rarefaction of the liquor is to be avoided:
e

page_text: For the necessary heating of the liquor I provide the collecting drum W² of
the centrifugal machine with an encasing shell Was represented in fig. 5 and use the
intervening space was a heating chamber. The heating can be effected by means of
steam or by the application of hot water, the branch c is provided with this object to
Serve as the inlet for the heating medium while the branch d serves as the
discharge end of the same and with a view to lessen the conducting tendency of
the casing it may be provided with the wood lagging k fig. 5 or some other similar
material.
To prevent the before referred to escape of the small raw sugar crystals in the
centrifugal machine the ordinary centrifugal sieves may be replaced by the combined
sieves and which are arranged with a layer. of some filtering material d fig. 6 and
placed between two or three sieves of a small mesh; in fig. 6 of the accompanying
drawings b represents the ordinary sieve or wire netting or cloth and a the centrifugal
drum provided with perforations.
In working this apparatus the liquor discharged by the whitening process of the
sugar in the centrifugal drum is re-conveyed by means or a pump or compressed air
apparatus into the centrifugal machine and if the collecting vessel is provided with a
sufficient number of chambers the re-conveying of the liquor therein may be continued
as long as such a process would be considered desirable in the treatment of
sugar.
The liquor discharged from the centrifugal machine is collected by these arrange-
ments in the collecting vessel in a progressive state of purity and as the said liquor is
repeatedly re-applied in the same order a considerable saving is effected in the
quantity required for the operation as by this method of whitening the sugar only
about 5% to 15% of pure liquor is absorbed while the existing method requires from
30% to 60% of the same liquor, and moreover this method has the further advantage
of the impure liquor discharged from the centrifugal machine being in condition
nearly equivalent to the syrup adhering to the sugar crystals and which liquor
when worked with crude sugar mashed with syrup can be applied again as mash
syrup.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what 1
claim is :-
1. The method of treating sugar by systematically collecting the liquor flowing
from the centrifugal machine in several portions separated from one another to allow
of their being re-conveyed to the sugar in the centrifugal drum to be used again in
the next operation of the series in each succeeding one of which the liquor increases
in purity substantially as described.
.
2. In the treatment of sugar the combination with a centrifugal machine of a
collecting vessel such as B having chambers adapted to be brought successively into
communication with the centrifugal machine substantially as and for the purpose
described.
.
3. In the treatment of sugar the employment of a collecting vessel for the
purpose of dividing the liquor into separate portions to be successively applied
to the sugar in the centrifugal machine substantially as and for the purpose
described.
4. In the treatment of sugar the complete collecting vessel substantially as described
and illustrated in figures 1, 2 and 3 of the accompanying drawings.
5. In the treatment of sugar the collecting vessel substantially as described and
illustrated in figure 4 of the accompanying drawings.
6. With the object of retaining the liquor at a proper temperature for the renewed
application of the same as described in the first above written claiming clause the
application of an outer casing W₁ upon the shell W2 of the centrifugal machine for
the purpose of forming a heating chamber substantially as described and illustrated
in the accompanying drawings.

page_text: 7. In a centrifugal machine the forination of the wall of the revolving cage in
sections substantially as and for the purpose described and illustrated in figure 6 of
the accompanying drawings.
113-
11000
W. P. THOMPSON & BOULT,
Agents for the Applicant.