Improvements in and connected with Drying Kilns.
Year: 1897

page_text: Date of Application, 24th Aug., 1897--Accepted, 30th Oct., 1897
COMPLETE SPECIFICATION.
Improvements in and connected with Drying Kilns.
I, Dr. GEORG DOLLNER, of 1/2 Muhlenstrasse of Rixdorf near Berlin, in the
Kingdom of Prussia, German Empire, Chemist, do hereby declare the nature of
this my 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 drying-kilns in which the furnace or heat-generating-
chamber is placed higher than the drying-chambers and has for its object to
prevent the intense heat produced in the kilns and retained by the walls of the
same from burning or destroying the materials being dried and the working parts
of the kilu, during such time as the working of the kiln is temporarily interrupted.
It is a known fact that even organic matter (viz. animal and vegetable sub-
stances), which themselves in a dry state are easily inflammable can be perfectly
dried by the application of intense heat, as this heat is not conducted to the same
through a wall, but acts directly on the substances under treatment, the evaporating
water preventing the same from being burned or destroyed by the heat.
Machines or apparatus constructed on this principle are usually so arranged
that mixing-devices located on the inside of stationary masonry or rotating drums,
hurl or throw the wet material upwards into intense currents of hot air. Such
plant has been found satisfactory so long as the continuous operation of the same
is not interrupted, when however, such interruption takes place, the serious
difficulty and risk is encountered that the heat taken up and retained by the walls
during the working of the kiln, becomes again taken up or reabsorbed by the
drying substances and by the working and other parts of the kiln, now no longer
cooled. This re-absorption or reaction of the heat can attain so high a degree as
to produce ignition of the material under treatment, and even a total impairing
or destruction of parts of the kiln is also possible.
To remove such possibilities and risks is the object of my invention, and I
attain this by causing, when the operation of the kiln is temporarily interrupted,
a current of cold air to be conducted through the same which has the result of
entirely preventing all injury to the materials or to the kiln from the action of the
radiating heat.
To make my invention clear I refer to the accompanying drawing in which
Fig. 1 shows my improved kiln in vertical section.
From the said drawing it will be clear that I bring about the above desired
result by placing the furnace or heat-generating-chamber of the kiln V higher than
the chambers of the kiln W in which the drying operations take place.
If I presume that the drawing represents the kiln in working order, the hot air
currents, generated by the Fan or blower A, (said currents being intensely heated
on their passage,) these hot air currents enter or pass through the kiln in the
direction indicated by the arrow a, and not only effect the drying of the wet materials
but also cause the walls of the kiln to become intensely hot, which heat as before
indicated, passes again into the kiln with the before mentioned result, when, or
as soon as, the drying process is interrupted.

page_text: Hitherto these difficulties have been impossible of solution in the known or
previous constructions of such kilns especially where the furnace or heating
chamber is located under or beside the drying-chambers as even an air tight
closing of the fire-doors in such constructions, would be entirely useless to effect
the desired object.
In my improved kilu, however, the excessive heat can be easily withdrawn from
the kiln by simply opening the damper B of the chimney or stack C and allowing
a cold current of air to be drawn by suction. As soon as the damper B is opened,
the hot air-gases from the furnace, escape through the chimney C and exert a
powerful suction which causes simultaneously a current of cold air to be drawn
through the ventilating fan now out of action, in the direction indicated by the
arrows, and thus the heat radiating from the said walls is caused to have absolutely
no injurious effect on the materials in the drying chamber, nor on the working
parts of the kiln.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
A drying-kiln in which the materials to be dried, are directly in contact with
the fire-gases, characterised by the furnace or heat-generating-chambers being
placed higher than the drying-chamber, so that, upon the working of the kil
being interrupted, the hot air escaping from the furnace through the opened
chimney or stack effects or causes a suction of cold air through the said drying-
chamber or chambers, substantially as and for the purpose herein before described
and shown in the drawing.
...
Dr. GEORG DÖLLNER,
By Cassell & Co.,
Agents for the Applicant.