Improvements in the Manufacture of Glucose or Sugar.
Year: 1897

page_text: Date of Application, 26th June, 1897-Accepted, 31st July, 1897
COSTE LEIE DIEULFICATION,
'
'Improvements in the Manufacture of Glucose or Sugar.
I, LOUIS PHILIP BAUER of Peoria, County of Peoria, State of Illinois, U.S.A.,
Superintendent of Glucose Refinery, 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 :-
This invention relates to the manufacture of glucose or grape sugar from starch,
the method of which hitherto has been as follows:-The corn is first steeped in a
weak solution of sulphurous acid in order to facilitate the separation of the starcli
from the gluten of the grain. The starch is then removed and converted into
glucose or sugar by boiling it under pressure with the admixture of an acid, such
as muriatic, sulphuric, or oxalic acid. After the conversion has been effected, the
acid is neutralised by a suitable alkali. For sulphuric acid, carbonate of lime is
employed and for muriatic or oxalic acid, soda is used. Where sulphuric acid is..
employed and neutralised' it is found very troublesome and expensive to remove
the precipitate consisting of sulphates of lime, etcetera, and for this reason at most
of the factories the use of sulphuric acid is abandoned and muriatic acid adopted
as the converting agent, but although muriatic acid, being neutralised with soda,
forms no precipitate and thus does away with the expense of removing a precipi-
tate, still the use of this converting agent and its neutralisation, leaves a salt in
solution which cannot be removed, and therefore, though cheaper, results in the
production of an inferior article which is quite unfit for use for certain purposes,
and the muriatic acid also has a tendency to decompose more gluten, of which the
starch is by no means free, and which after it is once decomposed is more difficult
to remove than in its original state. Moreover, muriatic acid in the glucose or
sugar solution also causes the solution to caramelise at a comparatively lower
temperature and in less time, and the colouring matter thus produced necessitates
the use of more bone charcoal to remove it, and the presence of a larger quantity
of albumen makes it risky to use such glucose for syrup, as it aids fermentation,
thereby affecting the keeping qualities of the syrup.
It has been known or conjectured that if sulphurous acid (SO2) could be
successfully used as the converting agent, its employment would remove many
of the difficulties encountered in the manufacture of glucose and sugar, for this
acid is a gas which, when heated, is highly volatile and passes off readily from the
solution containing it, and therefore would not require to be neutralised and
consequently would leave no precipitates requiring removal and no injurious salts
in the solution. Moreover, unlike muriatic acid, it decomposes very little gluten,
and to a certain extent prevents or obviates caramelising before the conversion
is completed. While it has been known that sulphurous acid has the power of
converting starch into sugar and glucose it has been thought necessary to use it
in large quantities, in which case it would be too expensive to prefer it even to
sulphuric acid, as, if used in small quantities, it was supposed that the solution
would require to remain so long under the influence of heat in the converter
that the glucose would caramelise before the completion of the conversion and for
the same reason would be unfit for making high class goods. Further, as

page_text: sulphurous acid is highly volatile it does not readily combine with a boiling
solution, as do the other acids, and consequently as my own experiments have
proved, it is practically imposible to mix the gas with the hot solution in the
manner that other converting agents have been applied, and if imperfectly mixed
the conversion is imperfect, the starch at the top of the solution being converted
in whole or in part and on the way to caramelisation before the starch lower down
is affected sufficiently or has reached the point of conversion.
I have discovered by practical experiment a method of employing sulphurous
acid by which I can make a uniform conversion of starch into glucose or sugar
in the same short length of time as it can be done with sulphuric or muriatic
acid and by which all the difficulties above mentioned are overcome and this now
method consists, briefly stated, in charging the starch solution with the sul-
phurous acid gas before said solution is heated. In the cold state the starch solution
more readily absorbs the gas and holds it, and if the charging of the starcli be
done under a vacuum, which is the preferable method, the sulphurous acid will be
purer, as this will prevent as much as possible the sulphurous acid being converted
by contact with the air into sulphuric acid. When the starch has been thus
charged with the gas it is boiled under pressure, the mass of starch and its
contained gas being mechanically kept mixed together until the point of conver-
sion is reached, when it will be found that the conversion has been uniform and
even throughout the mass before any caramelisation takes place. The pressure
being removed, the volatile heated gas will readily escape from the mass, leaving
uo injurious precipitate or salt behind, and the escaping gas itself may be
collected by being brought into contact with cold water, and a solution of
sulphurous acid thus obtained for use in steeping the corn preparatory to making
the starch, whereby the cost of the process is materially diminished.
My method is specially valuable in the production of grape sugar of a high
degree of purity. Heretofore, so far as I am aware, the highest purity of sugar
reached by the use of muriatic acid as the converting agent is ninety two per cent,
and to reach this degree it is necessary to make the starch solution very thin or
watery, as a rule, (6° Beaume at a temperature of 60° Fahrenheit). After the
point of ninety two per cent. is reached the Hquor begins. to caramelise and the
conversion has to be stopped at that point, whereas by my method, without making
the starch so thin, I am able to continue the converting process until all the
dextrine is converted into sugar and obtaining ninety seven per cent., leaving
only about three per cent. of impurities to be removed by aid of bone charcoal
and centrifugals to produce a chemically pure article.
The apparatus which I employ is shewn diagrammatically in the accompanying
drawing.
A, A, are two vacuum mixing tanks in which the cold solution of starch is 'o
be charged with the converting agent, sulphurous acid gas. The starch is first
fed into the upper tank A through the pipe A, falling upon a perforated splash
piate A which divides it and causes it to fall into the tank in fine streams to
bring every part into contact more readily with the gas contained in the tank A.
A is a vacuum pump for pumping the air out of the tank A to produce a more
cr less perfect vacuum in both tanks. As is a pipe leading from the bottom of
the tank A into tank A¹ somewhat below the middle. This pipe is provided
with a stop valve A past, which the starch solution may at any time be fed from
tank A to tank A' where it should rise above the lower end of the pipe, the
relative quantities of the starch,solution-in respect to the tanks, to be in proper
working condition; being shown in horizontal dotted line.
B is a common sulphur furnace such as are ordinarily in use.in glucose and
sugar, factories for burning sulphur and generating sulphurous acid. A pipe B¹
conveys the sulphurous acid from this furnace to a perforated coil B2 placed at
the bottom of tank and a pipe convoys such gas from the tank A' to a
perforated coil B at the bottom of tank A. When the pipes A3, A5, are closed
and the vacuum pump A is operated; a vacuum is formed in the tank A above

page_text: ".
the starch solution and thereupon the air or gas contained in pipo B³ begins to
pass up from the perforated coil B towards the pump and through the starch in
said tank and as this tends to produce a vacuum in the upper part of tank A";
the gaseous contents of the nipe B' continue to be drawn from the furnace up
through the coil B and through the starch solution in the tank A
whereby the starch solution in both tanks is permeated by the gas,
the valves of the pipes A, Apeing open, the pipe A filled with
starch, and the pipe A submerged at its lower end in the starch con-
tained in tank A', so that the operation of charging the starch can be continued
simultaneously with the operation of feeding the starch into the upper tank or
from this into the lower tank, or both.
C is the converting tank made in the form of a horizontal cylinder mounted on
central trunnions to be revolved by the band wheel C. A steam pipe D'enters
this cylinder through a stuffing box at one end and inside the cylinder is cranked,
and perforated at D plugged at the end' d, and joined to the pipe E which passes
out through a stuffing box in the other trunnion of the cylinder where it connects
with the pipe E. The end of pipe E is furnished with a common check valve
opening into the pipe from the cylinder and normally held closed by a spring or
other means. A stop valve is located in the pipe E. A pump is connected
with the lower tank A' by a pipe and its outlet pipe F is so arranged that by
means of the coupling Fit may be connected to the short feed pipe F of the
converting cylinder when the latter is standing still, and disconnected when
said cylinder is to be rotated. The pipe E' passes into the cooling tank G from
the upper part of which a gas pipe I leads to the chamber the latter being
provided at its upper end with a series of splash plates j, down which a streani
of cold water is kept playing and afterwards discharged at the outlet J. This
arrangement permits the cold starch solution after it is fully charged with the
reducing gag to be pumped from the lower tank A into the converting cylinder C
and therein subjected to agitation by the revolution of the cylinder and to the
heating action of direct steam blowing into it through the pipe D' at a pressure
of about 40 pounds per square inch which is maintained until the starch has
reached the point of conversion into glucose or sugar. When the starch is fully
converted, the valve E in the pipe is opened, whereupon the pressure in the
cylinder or tank C forces open the check valve 13 and the liquid contents of the
cylinder flow through the pipe E into the pipe E and are delivered into the
receiving tank G where, the pressure being removed, the heated and volatile
Sulphurous acid gas rises from the mass and passes through the pipe II into the
collecting chamber J, where it is caught by the trickling stream of cold water
end the larger portion of it enters into solution with said water, and this solution
of sulphurous acid gas flows down, discharges through outlet J, and is collected
and saved for use in steeping corn of which the starch is to be manufactured
It will be seen that the conduct of the process may be practically continuous.
Although the apparatus described and shewn is suitable for performing the
process, this may be accomplished by a great variety of appliances, the essential
feature being to charge the starch with the gaseous converting agent before the
starch is heated and then to heat the starch to the point of conversion, 'substantially
as stated, by any suitable appliance or apparatus.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim, is:-
1. The process of converting starch into glucose or sugar, consisting in charging
the starch solution in a cold state with a gaseous converting agent, such as sul-
phurous acid, and subsequently heating the starch under pressure to the point
of conversion, substantially as specified.
2. The process of converting starch into glucose or sugar, consisting in charging
the starch solution in a cold state with a gaseous converting agent, such as sul-

page_text: phurous acid, said gaseous converting agent being drawn into the starch under a
vacuum, and subsequently heating the starch under pressure to the point of
conversion, substantially as specified.
3. The process of converting starch into glucose or sugar, consisting in charging
the starch solution in a cold state with a gaseous converting agent, such as sul-
phurous acid, subsequently heating the starch under pressure to the point. of
conversion, subsequently removing the pressure from the product and collecting
the sulphurous acid which rises therefrom in water to form a solution, and save
the same, substantially as specified.
4. The apparatus for charging the cold starch solution with sulphurous acid,
consisting of two vacuum tanks or chambers connected together so that the starch
will feed from one to the other, a sulphurous acid generator connected to the
bottom of one of the chambers and a gas connection from the upper part of this
chamber to the bottom of the other chamber, substantially as specified
5. The combination of the sulphurous acid gas generator, means for delivering
said gas from the generator to the charging tank or tanks, which is or are,
adapted to contain a cold solution of starch, and to charge said solution with the
gas, the converter consisting of a closed chamber adapted to contain the solution
of starch charged with the gas and to heat the same under pressure, means such
as a pump, for conveying the charged starch solution from the charging tank or
tanks to the converter and a receiving tank connected to the converter, substantially
as specified.
6. The combination of the sulphurous acid gas generator, means for delivering
said gas from the generator to the charging tank or tanks, which is or are, adapted
to contain a cold solution of starch, and to charge said solution with the gas, the
converter consisting of a closed chamber adapted to contain the solution of starch
charged with the gas and to heat the same under pressure, means,, as a pump, for
conveying the charged starch solution from the charging tank or tanks to the
converter, and a receiving tank connected to the converter, and closed to confine
the gas, and a gas collector wherein the gas freed by the heat in the converter
is collected in watery solution, and a connection between the receiving tank and
the gas collector for conveying the gas to the collector, substantially as specified.
Dated this 26th day of June 1897.
THOMAS R. SHILLITO
89 Chancery Lane, London, W.C., Agent for the Applicant.