Improved Process for Drying Substances.
Year: 1897

page_text: Date of Application, 8th Mar., 1897-Accepted, 29th May,
1897
Improved Process for Drying Substances.
I, HANS HUMBSER, of 26 Bäumenstrasse Fürth, Bavaria, 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 statenient :-
This invention relates to a process for drying, by means of air in motion, substances
which contain constituents that are easily volatilisable under heating, the said air
being first deprived of its moisture before entering the drying chamber, and then
warmed to such a limited extent that a deterioration of the goods by volatilisation
of the said volatile constituents cannot occur, only moisture being abstracted
therefrom.
This improved process is more particularly intended for the treatment of substances
of the plant kind which contain aromatic oils, that volatilise casily at low temperatures,
such as hops.
The process is advantageously carried out in such manner that dry air at a
temperature below that at which the volatile constituents of the substance are
volatilised is led into the drying chamber, where it takes up a small amount of moisture
corresponding to its temperature.
If this moist air current be then cooled to a low temperature, the moisture
contained therein will be precipitated, and consequently the air will be dried. The
same air can then be led to a heating stove in order to be warmed to a temperature
below that at which the said constituents are volatilised and it is then again passed
into the drying chamber in order to take up a farther quantity of moisture from the
substances.
The accompanying drawing shews an apparatus suitable for carrying out the
above described process.
Figure 1 shows a vertical section on line II-II, Figure 2 ; and
Figure 2 shews a horizontal section on line I-I, Figure
The drying chamber R is divided into compartments a¹ a³ a separated from each
other by hurdles hand h. The material to be dried is introduced through the
opening o closed by a door, and it is removed from the lowest compartment a³ through
the opening t, also closed by a door.
The hurdles h¹ and are so arranged (such as by making them with pivotted
louvre blades as shown) that the goods to be dried can, without opening the chamber R
be transferred from the top compartment to the bottom one.
K is the cold chamber and W is the heating chamber.
The three chambers R, K, W are connected with each other by a channel ; an
air propellor v serves for producing the air currents.
The action of the apparatus is as follows: The goods contained in the drying
chamber R have an air current passed through them which is forced by the propeller v
in the direction of the arrows into the cold chamber K. Here the air is cooled to a
low degree (such as down to -10° C.) so that the moisture contained therein is deposited
on the walls of the chamber K,
This cold dry air is then passed into the warming chamber W whore, as already
stated, it is raised to a temperature below that at which the volatile constituents of
the goods are volatilised (such as to + 4° C.). The air then again enters the chamber R
and takes up fresh moisture from the goods. The aromatic constituents of the goods
are not affected by this action and consequently remain unchanged.

page_text: Although the air currents, being only slightly warmed, only take up a
comparatively small quantity of moisture from the air each time, yet hy accelerating
the flow of the air the duration of this drying process can be shortened between
certain limits.
The drying of the air can also be facilitated by the provision of hygroscopic
substances in the chambers K or W.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. A process for drying substances containing easily volatilised constituents, by
means of air currents, consisting in subjecting the air employed for drying, before
entering the drying chamber, first to a process whereby it is deprived of its moisture
and then to a process for warming it to a temperature below that at which the
volatilisation of the said constituents would occur, substantially as described.
2. In the process for drying substances by means of air currents referred to in
the first claim, causing the air currents required for drying to circulate first through
a cold chamber, such as K for cooling it to a low temperature and thereby depriving it
of moisture, then through a warming chamber such as W for warming it and
thereby increasing its capacity for absorbing moisture, and then through the drying
chamber R. containing the substance, to be dried.
ABEL & IMRAY,
Agents for the Applicant.