Improvements in Apparatus for Drying Fruit and the like by Air and Furnace Gases.
Year: 1896

page_text: Date of Application, 11th Dec., 1816-Accepted, 1st May, 1897
COMPLETE SPECIFICATION.
Improvements in Apparatus for Drying Fruit and the like by Air
and Furnace Gases.
I, OSCAR SCHMEISSER, of No. 25 Cladowstrasse, Lan Isberg-on-the-Warthe, in
the German Empire, 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 :-
This invention relates to the drying of material which is in pieces, such as stone
fruit, when the stones have to be dried without becoming separated from the fruit.
In such case it is necessary to dry the stone with the flesh of the fruit, that is to
say the fruit has to be dried as a whole; the stone generally must be kept at a
temperature below the boiling point, while the flesh of the fruit as long as it
protects the stone may be exposed to a higher temperature. If the stones are very
susceptible, the temperature of the drying gases must be gradually decreased, as
evenly as possible as the fruit is becoming dried, until the fruit has been completely
dried.
In order to render this possible on a large scale and to allow of continuous
working, according to this invention the material to be dried is fed in a long
stream, directed with regard to the current of gases of combustion in such a
manner that there is a relative parallelism between the stream of material and the
current of gases of combustion as regards the gradual cooling of the current of
gases of combustion by the drying current, which crosses the former on its way
from the furnace to the chimney; or the same effect may be produced by the
increasing admission of cold air to the gases of combustion; the fresh fruit is
exposed to the largest amount of heat and the dry fruit to the least amount of
heat.
In order to prevent the mixing of the drying gases of different temperatures on
the other side of the channel from the gases of combustion, that is to say before
crossing the stream of material, and thus destroying the beforementioned relation,
the arrangement is so that the drying gases of different temperatures are collected
in separate compartments whence they cross the stream of material which passes in
front of orifices in the compartments, and are afterwards sucked off from a common
exit compartment by exhaustion, in order to be used, if desired, for the preliminary
heating of material to be dried.
In order that my invention may be the better understood, I now proceed to
describe the same with reference to the accompanying drawings and to the letters
and figures marked thereon.
Figures 1A and 1B show horizontal longitudinal sections of the apparatus.
Figures 2 and 2 show vertical longitudinal sections on the line x- and y-y
of Figures 1A, 1B.
Figure 1 is a horizontal section through the fuel grate.
Figure 3 shows a transverse vertical section.
Figure 4 shows a detail drawn to a larger scale and
Figure 5 shows a modified detail.
The drying is to be effected by fuel burnt on the grate a. The gases of combustion
pass either through the channel b to the chimney, and are cooled in their passage
to such an extent that only sufficient heat passes to the chimney to produce the

page_text: necessary draught; or they are utilized for drying and are sucked off through the
side of the channel, a corresponding amount of cold air being mixed with them
during their passage.
In the first case the current of the gases of combustion is cooled by a current of
cold air crossing it through tubes c which allow of the transmission of a great
quantity of heat and are conveniently made of sheet iron or sheet copper.
As the
curreut of drying air, on account of its comparatively low temperature, is much
larger than the current of fire gases, it is necessary to have a large tubular or
heating surface in order to produce the required cooling of the current of fire
gases. For this purpose a large number of tubes is arranged in the fire channel.
If the cross section of all tubes is alike, and the air, to be heated passes in all tubes
with equal velocity, the air will be heated more in the tubes near the furnace than
in the tubes near the chimney. In consequence the drying air will leave the
other side of the fire gas channel at different temperatures, decreasing from the
furnace.
In the second case the same object will be obtained, if the current of the gases
of combustion is combined with the drying gases.
The opening to the chimney, and the heating tubes c are not required in such
case.
Through the orifices in the wall cold air enters, and through the corresponding
opposite holes on the other side of the fire gas channel cold air and warm gases of
combustion escape mixed, this mixture of gases, used to dry the material, will also
be of different temperature at the various holes, the degree of temperature being
decreased as the distance from the furnace increases.
To prevent the mixing of the drying gases of different temperatures, they pass
into separate compartiments, that compartment near the furnace containing the
hottest and that near the chimney the coolest drying air.
Each of these compartments has an orifice through which the drying gases can
pass to the stream of material which is passed along the compartments parallel to
the current of the gases of combustion that is to say in such a manner that the fresh
fruit receives the greatest heat and that the fruit receives gradually less heat as it
gradually becomes dry. By this arrangement the drying air is compelled to pass
through the stream of material and to pass around the separate fruits at the before
mentioned different temperatures.
Nevertheless, the fruits close to the impinging gases will become somewhat
warmer than the fruits behind. Therefore, it is necessary that the fruit sball
become mixed during its passage. The feeding and mixing may be effected in a
number of ways.
According to the present construction a long perforated cylindrical drum e is
provided for this purpose which passes in front of the orifices of all compartments d
and is rotated by gearing ff. The interior of the drum e may be provided with
agitating bars, 9, (Figure 2B) for the material fed through the funnel h or the shell
of the drum may have long holes or ribs placed either obliquely or spirally. In
order that the drying gases can only pass into the stream of material and cannot
escape in any other direction, shields are fixed to the wall as shown in the
construction illustrated in Figure 3, which at the openings of each compartment
come into contact with the periphery of the drum, so that the drying current is
compelled to pass through the stream of material in the direction of the arrow.
The drying gases or heated air which have passed through the stream of material
to be dried are collected in the common exit compartment k from which they are
sucked, through an exhausting pipe connected to the orifice 7 (Figure 2B) after they
have fulfilled their drying-office in a direction opposite to the movement of the
drying material, in order to be used, if desired to preliminarily heat the fresh
fruit.
In the construction shown in Figure 5, a fixed sieve m is arranged concentrically
with the drum before the opening of each compartment d, and the drum, rotating
close above it, is provided with oblique long holes, which are much larger than the

page_text: fruits dried. The latter will therefore rest mainly on the fixed sieves and be
horizontaly transported and mixed by the elongated holes. In this way the drum
may be kept cooler and the shields may be omitted if desired.
The arrangement of the orifices in front of which the drum rests will of course
depend on the angle of which the material collects.
The drum is preferably mounted by rings, connecting the various sections, on
rollers n Figure 3. These rollers as shown in Figure 4, are arranged in boxes o
the interior of which is connected with the outer atmosphere, so that they are
always cooler by the current of air caused to pass through the boxes by the suction
of the drying gases from the compartment k.
The end of the drum is conveniently provided with a suitable closing device, to
allow of the discharge of the fruit without admitting cold air.
The regulation of the temperature of the separate compartments d can be
effected through orifices p by cold air, or by closing a greater or less number of
tubes c.
It may happen that the pieces of the material are not of equal size and that
sorting of the same before drying is not advisable for various reasons.
If large
and small pieces are dried simultaneously, the smaller pieces will be dried quicker
than the larger pieces, because they offer a comparatively large surface as
compared with their volume. In consequence there is danger of the pieces
already dried becoming overheated by remaining in a temperature too hot for
them. It is therefore necessary to separate the small pieces as they become dry.
For this purpose holes or slots are arranged in the drum e a suitable distance from
the furnace through which the small pieces can escape and pass to suitable
recepticles to protect them the against overheating.
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 :-
1st. A drying apparatus for material which is in the form of pieces, such as
stone and similar fruit, in which the material is fed in a long continuous stream in
the same direction as the hot gases of combustion proceeding from a fuel furnace
and in which the drying gases or air passing through the fruit heated to different
degrees of temperature by passing through the current of gases of combustion, or
by being mixed therewith, are collected in separate compartments d for the purpose
of preventing their becoming mixed on the other side of the fire gas channel b
from which compartments they cross the stream of material and pass into a
common exit chamber k from which they may be sucked off in a direction opposite
to that of the stream of material.
2nd. A drying apparatus, as claimed in Claim 1, in which the material is
transported by means of a long perforated rotary drum e provided in its interior
with agitating bars 9 or having agitating and transporting holes in the shell
situated either obliquely or spirally which drum is in contact with side shields i
and arranged in front of the openings of the compartments d in such manner that
the drying gases are compelled to pass through the stream of material.
3rd. In a drying apparatus as claimed in Claim I the arrangement of the drum e
claimed in Claim 2, on rollers n, which are always kept cool by a current of air
caused by the exhaustion of the exit chamber k and passing through bearing boxes o
of the said rollers communicating with the outer atmosphere and the exit chamber.
4th. In a drying apparatus as claimed in Claim 1 the arrangement of a sieve m
fixed, concentrically to the drum over the openings of the compartments d,
Figure 5, in combination with very large. elongated holes in the shell of the drum
so that the material rests essentially on the sieve m and is only transported and
agitated by the drum.
5th. In a drying apparatus as claimed in Claim 1, for the purpose of the uniform
drying of material in pieces of a like size, the separation of small pieces from the
stream of material by means of the same drum e by forming the holes of the

page_text: drum from a suitable part thereof in such a manner that the small and therefore
quickly dried and shrivelled pieces become separated by sieving.
Dated this 11th day of December 1896.
FELL & JAMES,
Agents for the Applicant.