IMPROVEMENTS IN APPARATUS FOR EMPLOYING HEATED AIR IN DRYING OR BAKING VEGETABLE OR OTHER SUBSTANCES.
Year: 1879

page_text: LETTERS PATENT to Samuel Cleland Davidson, of Belfast, in the County of
Antrim, Ireland, Gentleman, for the Invention of "IMPROVEMENTS IN
APPARATUS FOR EMPLOYING HEATED AIR IN DRYING OR BAKING VEGETABLE
OR OTHER SUBSTANCES.
"
Sealed the 14th October 1879, and dated the 16th April 1879.
PROVISIONAL SPECIFICATION left by the said Samuel Cleland Davidson
at the Office of the Commissioners of Patents on the 16th April 1879.
SAMUEL CLELAND DAVIDSON, of Belfast, in the County of Antrim, Ireland,
Gentleman. "IMPROVEMENTS IN APPARATUS FOR EMPLOYING HEATED AIR IN
DRYING OR BAKING VEGETABLE OR OTHER SUBSTANCES."
The apparatus which forms the subject of my Invention consists of a drying
chamber, into which sieves or other suitable carriers for the material to be dried or
baked are inserted. An air chimney is attached for exhausting the air from this
chamber and for drawing it through the material therein, and can be arranged so
that the smoke and hot gases from the fire which is employed in the apparatus
producing the heated air may be led into the chimney in order to raise the tempe-
rature and increase the draft power therein. Below the sieves or carriers within
the chamber is a self-emptying hopper which guides any of the material falling
through these sieves into a receiving tray underneath, and a space is left between
this receiving tray and the lower edges of the hopper as a passage to allow the
heated air to ascend between them to the sieves above. The heated air is admitted
into the bottom of the drying chamber below this receiving tray, and may be
produced by any air heating apparatus before entering this drying chamber.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Samuel Cleland Davidson in the Great Seal Patent Office on the
15th October 1879.
SAMUEL CLELAND DAVIDSON, of Belfast, in the County of Antrim, Ireland,
Gentleman. "IMPROVEMENTS IN APPARATUS FOR EMPLOYING HEATED AIR IN
DRYING OR BAKING VEGETABLE OR OTHER SUBSTANCES."
The apparatus which forms the subject of my Invention consists of a drying
chamber, into which sieves or other suitable carriers for the material to be dried
or baked are inserted. An air chimney is attached for exhausting the air from this
chamber and for drawing it through the material therein, and may be arranged so
that the smoke and hot gases from the fire employed in the apparatus producing
the heated air may be led into it in order to raise the temperature and increase the
draft power therein.
Between the sieves or carriers and the base of the drying chamber is a self-
emptying hopper, which guides any of the material falling through these sieves
into a receiving tray underneath, and a space is left between this receiving tray
and the lower edges of the hopper as a passage to allow the heated air to ascend
between to the sieves above. The heated air is admitted into the base of the
drying chamber below the receiving tray, and may be produced by any air heating
apparatus before entering this drying chamber.
The accompanying Drawings illustrate the construction of the apparatus.
Figure 1 is a vertical section through the drying chamber air flue and chimneys,
the sieves being withdrawn from the drying chamber.
Figure 2 is a front elevation of the drying chamber with the sieves in their
places, and of the air flue and chimneys.
Figure 3 is a vertical transverse section of the drying chamber with an end
elevation of the air flue and basement of chimneys.
Figure 4 shows in plan, section, and elevation one of the sieves or carriers for
holding the material to be dried.
Figure 5 represents in a similar manner the receiving tray which is situated
beneath the hopper.
Figure 6 is a plan showing the construction of the sides of the drying chamber.
The letters which indicate the several parts of the apparatus are the same in
each Figure, and are as follows:-
A, drying chamber.
B, hopper shelves.
C, protecting shelf or table for the receiving tray.
D, openings in the drying chamber for admitting the sieves.
D¹, sieves.
E, opening in the drying chamber for admitting the receiving tray.
El, receiving tray.
E2, openings in the front of the receiving tray to admit cold air.
F, angle iron ledges along the inside of the drying chamber for the sieves to slide
and be supported upon.
G, opening in the top of the drying chamber for the exit of the air.
H, air flue for carrying the air from the top of the drying chamber to the base of
the air chimney.
J, damper door in air flue.
K, air chimney.
L, smoke chimney from the furnace of the apparatus employed in heating
the air.
M, hot air flue or chamber from which the heated air ascends into the drying
chamber.

page_text: The sides of the drying chamber A, A, are formed by a double casing of (by
preference) sheet iron with a space between, which is filled with any suitable
material of low conducting power for heat to check loss by radiation from the
sides. The hopper shelves B, B, and the protecting shelf C are also similarly formed
to prevent any direct radiant heat acting upon the trays E¹ and D', D', from any
highly heated pipes or plates that may be employed for heating the air within the
flue or chamber M beneath the drying chamber.
The shape, arrangement, and construction of the sides of the drying chamber
A, A, and hopper shelves B, B, and protecting shelf C are sufficiently indicated by
Figures 1, 2, 3, and 6 in the accompanying Drawings to require no further
explanation, and the same may be said of the air flue H, the air chimney K, and
the smoke chimney L, and Figures 4 and 5 fully illustrate all that is necessary as
regards the sieves or carriers D', D¹, and E¹. These trays are here shown as made
with wire web netting supported within a wooden framing, but any other per-
forated material may be used which will allow the air to pass freely through it.
In Figures 1, 2, and 3 a damper door J is shown in the air flue H. This damper
door when in the position indicated by the dotted lines in Figure 1 shuts off com-
munication between the drying chamber A, A, and the air chimney K, and at the
same time leaves the top of the air flue open for the exit of the heated air from the
drying chamber, and this arrangement is used when a strong draught through the
chamber is not required. For ordinary use however a strong draught is required,
and to produce this the damper door J is raised again so as to close the opening
in the top of the air flue and give a free passage to the air from the drying chamber
through the air flue to the air chimney K, and it is intended that the smoke from
the furnace arrangement for producing the heated air may be projected into the air
chimney in line with the descending air current by means of the smoke chimney L,
as shown, this smoke chimney being carried up the air chimney only a short
distance so that the smoke and air mix together in the chimney K, and as the
smoke is usually at a much higher temperature than the air from the drying
chamber it raises the average temperature in the air chimney K. and thereby
accelerates the draft considerably. The arrows indicate the direction of the current
of the heated air through the drying chamber to the air chimney, and it will
readily be seen that the hopper shelves B, B, and protecting shelf C while preventing
the radiant heat from striking up against the sieves in the drying chamber, at the
same time allow the heated air to ascend freely through the passages left between
them for this purpose, and that any dust or fine material falling through the meshes
of the sieves D¹, D¹, will be directed by the hopper shelves across these air passages
on to the receiving tray E¹, from which it can be removed occasionally. The pro-
tecting shelf C prevents the material upon this tray from being overheated, and the
openings in the front of the tray, as shown at E2 in Figure 2, further assist in this
respect by allowing cold air to be drawn in and up through the material upon the
tray by the strength of the air chimney draft, thus effectually keeping the material
cool. The hopper is shown as constructed with two sloping shelves, but it may be
constructed with more if preferred. The drying chamber is shown as constructed
for only four sieves, but this number may be increased or diminished as required.
The material to be dried is placed upon the sieves D¹, D¹, and the current of hot
air which is drawn through it by the chimney arrangement for draft carries off the
moistnre from it. The material upon the lowest sieve will naturally be the first
dried, and when finished it should be removed and the one above it put into its
place, and those again above that changed one move down. The sieve with the
fresh supply of material is then put into the top place, where it remains till the
bottom sieve is dry and removed, when all the sieves are again changed one move
down as before, and fresh material put in at the top, and in this way the drying is
accomplished in an even and regular manner.
Having now described the nature of any said Invention, and in what manner the
same is to be performed, I declare that I claim as my Invention the general combi-
nation, arrangement, and construction of the parts composing the apparatus, as

page_text: herein before described, a special feature in the part described as the drying
chamber being the use between the sieves carrying the material and the supply
chamber for the heated air of sloping shelves to form a self emptying hopper,
having a receiver or tray underneath to catch any material falling through, and
having a space between this tray and the hopper for the passage of the heated air
from the supply chamber to the sieves, and another special feature of the apparatus
being the combination with the drying chamber of an air exhausting flue and
chimney in which the draft is accelerated by having the hot gases from the fire
which is used in the air heating arrangement projected into the base of the chimney,
in the manner and all substantially as hereinbefore described and represented in
the accompanying Drawings.
In witness whereof, I, the said Samuel Cleland Davidson, have hereunto set
my hand and seal, this Second day of October, One thousand eight hundred
and seventy-nine.
S. C. DAVIDSON. (L.S.)