IMPROVEMENTS IN THE MANUFACTURE OF SUGAR, AND IN APPARATUS TO BE EMPLOYED THEREIN
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William Edward Halse at the Office
of the Commissioners of Patents on the 23rd July 1881. A communication
from abroad by Uwe Esmarch and Emil Passburg, of St. Petersburg, Empire
of Russia.
THE
WILLIAM EDWARD HALSE, of Mincing Lane, in the City of London, Analytical.
Chemist. "IMPROVEMENTS IN THE MANUFACTURE OF SUGAR, AND IN
APPARATUS TO BE EMPLOYED THEREIN." [A communication from abroad by Uwe
Esmarch and Emil Passburg, of St. Petersburg, Empire of Russia.]
This Invention relates to an improved method of effecting the drying of refined
sugar, and consists in the employment, either alternately or combined, of an elevated
temperature and a vacuum upon refined sugar contained in a peculiar arrangement
of apparatus, whereby the water contained in the syrup with which the refined
sugar is contaminated is more economically and advantageously removed than by
the processes or in the apparatus now generally adopted.
In carrying out this Invention the sugar contained in suitable forms or moulds is
subjected to a preliminary heating process in a closed chamber constructed of iron
or other suitable materials, and licated either internally or externally by means of
steam or hot water contained in pipes or otherwise. It is preferred to arrange the
forms in this chamber with the apices of the cones pointing upwards, in order to
allow the solution of sugar which accumulates in the apex during the process of
draining to be distributed uniformly throughout the mass in the form, and also to
allow the moulds to descend freely or settle down upon the loaves of sugar as the
latter contracts, so as to obviate the liability to form cracks or flaws in the said
loaves; but other arrangements may be adopted.
The chamber in which the preliminary heating is effected may be heated in any
desired manner, but it is found to be of advantage to employ for this purpose a flat
box or chest of polished cast iron, divided internally by partitions extending nearly
from one side to the other, and so arranged as to form a long zig zag passage for the
steam, which enters the box at one end and leaves it at the other, after traversing
the zig zag passage hereinbefore described, which presents a very extended heating
surface. This chest or heater is either laid flat on the bottom of the heating
chamber, or arranged on its edge at the side of the said chamber.
In order to effect and during the preliminary heating process to which the sugar

page_text: is exposed a temperature of from about sixty five to about eighty degrees
centrigrade is employed, and is continued for from about six to about
eight hours, according to the size of the loaves or forms under treatment, after
which the loaves are removed by hand, or preferably by suitable mechanical
appliances, and placed in an apparatus next hereinafter described, where they are
exposed to the action of heat and of a vacuum, either alternately or combined.
This apparatus consists of an hermetically closed chamber constructed of sheet
iron, for example, and provided internally with a frame or rack capable of revolving
upon a vertical axis, and constructed with radiating and annular concentric
partitions, forming receptacles or compartments in which the forms are held,
retained, or suspended with the apices of the cones downwards. The forms are
suspended from the frame by means of rings formed in two segments, connected by
bolts, to which are attached hooks engaging with the revolving frame.
This chamber is provided with a suitable aperture at its upper part capable
of being hermetically closed, serving for the introduction or removal of the forms,
the frame being caused to rotate upon its vertical axis, so as to bring the compart-
ments in succession under the opening. The chamber is heated by means of
steam, which is caused to circulate in a pipe or worm arranged at the bottom or
other convenient part of the apparatus, and is also connected with an air pump of
any suitable construction in order to obtain the required vacuum. Between the
air pump and the chamber there is arranged a condenser for the purpose of
condensing the vapour produced by the evaporation of the moisture contained in
the sugar. Any suitable surface or other condenser may be employed for this purpose,
but it is preferred to employ a surface condenser constructed as next hereinafter
dsecribed, which affords peculiar facilities for watching the progress of the drying
operation.
This condenser is constructed with two concentric cylinders contained in a
suitable cylindrical case, the inner cylinder being provided internally with ribs, webs,
or projections, and similar projections are also provided on the external surface of
the outer cylinder to assist in the radiation of heat.
A small annular space of about a quarter of an inch is formed between the two
cylinders, and the vapour charged with moisture from the sugar in the heating
chamber being drawn through the condenser by the action of the air pump first
enters a wide annular space at the upper part of the condenser, and passes thence
_ into the narrow annular space herein before referred to, where it is condensed by
the action of the cold water contained in the interior of-the-inner-cylinder, and also
in the space between the outer cylinder and the case of the condenser. The
moisture thus condensed flows down the sides of the cylinders and drips from an
inclined ledge arranged below the narrow annular space, hereinbefore described,
into a suitable chamber or receptacle at the lower part of the apparatus.
This chamber is provided with suitable glazed peepholes through which the
quantity of condensed moisture flowing from the condensing surfaces and dripping
from the ledge may be watched in order to ascertain when the operation is
completed.
In order to dry sugar by means of this apparatus, the forms containing sugar
loaves, which have been previously heated to required temperature in a heating
apparatus similar to that firstly herein before described, are placed in the compart-
ments of the revolving frame or rack in the heating apparatus similar to that
secondly hereinbefore described, which is then hermetically closed, and the sugar
which it contains is exposed to the action of heat and of a vacuum, either simul-
taneously or alternately, until the sugar is sufficiently dried, which is known to be
the case when it is observed that the condensed moisture in the condenser ceases to
drip into the chamber herein before described.
It has been found that in practice three successive heatings, each followed by the
application of the air pump, are usually sufficient to completely dry the largest
loaves containing from 3 to 4 per cent. of moisture, but refined sugar in the form
of slabs or bars can be dried in a much shorter space of time.

page_text: A larger number of loaves may be dried at one operation by employing suitable
modifications of the drying apparatus, as next hereinafter described. According to
one of these modifications the drying chamber is provided with four or other
suitable number of revolving racks for the reception of the loaves, each rack being
mounted on a separate vertical axis, and constructed in a similar manner to the one
hereinbefore described, the chamber being also provided with a corresponding
number of suitable apertures for introducing or removing the forms. Suitable stays
are provided in this case between the racks to required strength to the sides of the
chamber, in order to enable it to resist the pressure of the atmosphere.
According to another modification a series of revolving racks carrying the forms,
as hereinafter described, are arranged one above the other, being capable of
revolving independently on the same axis in a cylindrical drying chamber. A
vertical shaft is arranged in the centre of the chamber and carries suitable rings or
collars which serve to support the revolving racks, coils of pipe being provided at
the upper and lower extremity of the chamber as well as between each rack for
the circulation of steam. The moisture evaporated from the sugar in both of these
modifications is drawn off to the condenser by means of the air pump and the
action of heat, and vacuum is applied in the same manner as in the drying
apparatus firstly herein before described, but in the modification of the apparatus
lastly hereinbefore described the racks consist of a sleeve turning upon the central
vertical shaft and provided with radial arms carrying conical rings or sockets which
receive and support the small ends of the forms, the large end or base of the latter
being upwards.
The cylindrical chamber of this apparatus is also provided with openings in its
sides (capable of, being hermetically closed) for the introduction and removal of
the forms, and arranged in the form of a helix round the chamber in order to
enable the workmen to obtain access to all the racks at the same time without
inconvenience.
If desired the preliminary heating process in a separate chamber may be dispensed
with, and the entire operation performed in the chamber connected with the
condenser and air pump.