Improvements in Apparatus for Drying Tea or Tobacco Leaves, Coffee, Fruits, Cloths, and other Substances, and for the Baking of Tobacco Stems and other Substances.
Year: 1897

page_text: Improvements in Apparatus for Drying Tea or Tobacco Leaves,
Coffee, Fruits, Cloths, and other Substances, and for the Baking of
Tobacco Stems and other Substances.
I, SAMUEL CLELAND DAVIDSON, of Sirocco Engineering Works, Belfast,
Ireland, Merchant, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improved apparatus for drying tea or tobacco leaves,
coffee, fruits, cloths or other substances; or for the baking of tobacco stems or
other substances and consists of a drying or baking room or chamber (hereinafter
called the drying chamber) with an air-heating apparatus constructed below it
and connected therewith by flow and return air flues, whereby a self-acting upward
current of air ascends and flows from the heater through one or more of said
flues into the drying chamber, and return currents pass back therefrom down the
other flues into the base of the heater, so that a continuously circulating natural
current is thereby maintained in the drying chamber.
My improved apparatus may be conveniently constructed in the form of a
brick or masonry building, consisting of two rooms, one above the other, with
a fireproof floor between them, the lower of which rooms contains the air heater,
and the upper constitutes the drying or baking chamber, through the floor of
which the air flues pass which connect it with the air heating apparatus in the
room below.
The drying chamber may be fitted with any suitable appliances whereby the
material to be dried or baked may be exposed to the influence of the circulating
current of heated air passing through it, such for instance as with frames of
racks or shelves carrying trays of wire web or other foraminous material, on which
the substances to be dried or baked may be spread in thin layers; and such
arrangement of trays is specially suitable for drying tea, coffee, or fruits, and
more particularly for the final firing or baking of tea preparatory to its being
packed into chests for transport; and also for the baking of tobacco stems
preparatory to their manufacture into snuff; but when my improved apparatus
is employed for the drying of fresh cut tobacco leaf, a convenient arrangement
is to have cords stretched from end to end of the room, and at either side thereof,
with more or less of a passage-way between, on which cords clusters or bunches
of the tobacco leaf to be dried may be suspended, on the method ordinarily
adopted in the drying rooms hitherto usually employed for tobacco drying;
and this arrangement is also well suited for the drying of cloths.

page_text: When my herein-described apparatus is employed for "baking" purposes,
no ventilation is necessary in connection with the drying chamber; but when
employed for the drying of any damp material, one or more ventilators may be
employed, either in the roof or preferably in the walls and near the floor level
of the drying chamber, to provide for the escape of a proportion of the moist
air from the drying chamber; and in order that these ventilators may work
efficiently, small doors are constructed in the casing of the air heater, to admit
an equivalent amount of fresh air to the circulating current passing through
same.
The air heating apparatus which I preferably employ is that described in
the Specification of previous Letters Patent granted to me and dated 28th
September 1895 No. 18167, but I do not limit myself to this particular form
of air heater; and when I employ this apparatus I enclose it in a casing fitted
with the upward flowing and downward return air flues hereinbefore referred
to as connecting the air heating apparatus with the drying chamber; and the
space existing in the lower room around the air heating apparatus, is convenient
for storing fuel, and for the stoking of the air heater furnace.
When the drying chamber is fitted with racks and trays of foraminous material,
it is convenient to have them arranged on opposite sides of the room, which I
preferably make of oblong shape, with the entrance door at one end, and a
window for light at the other end, and with small doors in the side walls,
through which the material on the trays or on the suspending cords may be
inspected by the attendant from time to time, to ascertain its condition and
progress, without his having to go into the drying chamber to do so; and in order
that the attendant may more conveniently reach the highest of the shelves to
insert or withdraw the trays, or to hang the material to be dried on the highest
cords, a platform, constructed preferably of iron, is provided between the racks,
but not extending underneath them, and about 2 feet above the solid floor of
the room, and I locate the air flue, or air flues, for admitting the hot air from the
air heater about the centre of the room, and underneath this platform, so that
the inflowing air shall strike against the underside of the platform, and be
thereby deflected under the racks of trays; and I preferably carry the return
flues back to the air heater, from near the ends of the room, and project same
from the solid floor of the room up through the iron platform, so that the return
air may be drawn from near the surface of this platform; and also from each
end of the room and this same arrangement of the platform and air flues suits
likewise for the drying of fresh tobacco leaves, and also for the drying of cloths,
when suspended on cords, which practically take the place, and occupy much
the same position as the racks of trays herein before described; or the hot air
inlet flue may, if preferred, be fitted with distributing pipes, so as to spread
the air more equally throughout the room, and prevent the full force of the
current striking directly against any particular portion of the material to be
dried.
Some of the advantages arising from the employment of my herein-described
improved drying or baking apparatus, are that a large amount of material can
be uniformly dried or baked at one time, and by reason of the circulating current
the required heat is very equally maintained in all parts of the drying room,
and at any temperature suitable for the material to be dried, up to as high
as 250 or 300°; and by the employment of an economical air heating apparatus
such as herein before referred to, the work to be done is accomplished with great
economy of fuel.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London,
Chartered Patent Agents.

page_text: Improvements in Apparatus for Drying Tea or Tobacco Leaves,
Coffee, Fruits, Cloths, and other Substances, and for the Baking of
Tobacco Stems and other Substances.
I, SAMUEL CLELAND DAVIDSON, of Sirocco Engineering Works, Belfast,
Ireland, Merchant, 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; —
My invention relates to improved apparatus for drying tea or tobacco leaves,
coffee, fruits, cloths, or other substances; or for the baking of tobacco stems,
or other substances. The improved apparatus consists of a drying or baking
room or chamber (hereinafter called the drying chamber) with an air heating
apparatus (hereinafter called the heater) constructed below or alongside of it,
and connected therewith by flow and return air flues, whereby a self-acting
upward current of heated air ascends and flows from the heater through one or
more of the said flues into the drying chamber, and return currents of com-
paratively cooled air pass back therefrom through the other flues into the base
of the heater, so that a continuously circulating natural current is thereby
maintained in the drying chamber; or the said flow and return current may be
effected by means of fans, to accelerate the drying or baking of the material
in the drying chamber at comparatively lower temperatures.
My improved apparatus, may be conveniently constructed in the form of a
brick or masonry building, consisting of two rooms one above the other, with
a preferably fireproof floor between them, the lower of which rooms (hereinafter
called the heater chamber) contains the heater, and the upper constitutes the
drying or baking chamber, through the floor of which the air flues pass which
connect it with the heater in the room below; or, alternatively, the building may
consist of two rooms side by side, one constituting the drying chamber and the
other the heater chamber with connecting flues between, one for the flow current
from the top of the heater into the top of the drying chamber, and the other for
the return current from close to the floor of the drying chamber into the base
of the heater, to which latter à fan may be applied to accelerate the circulation
through the heater and the drying chamber.
The drying chamber may be fitted with any suitable appliances whereby the
material to be dried or baked may be exposed to the influence of the circulating
current of heated air passing through it, such for instance as with frames of
racks or shelves carrying trays of wire-web or other foraminous material, on which
the substances to be dried or baked may be spread in thin layers; and such
arrangement of trays is specially suitable for drying tea, coffec, or fruits, and
more particularly for the final firing or baking of tea preparatory to its being
packed into chests for transport; and also for the baking of tobacco stems
preparatory to their manufacture into snuff; but when my improved apparatus
is employed for the drying of fresh cut tobacco leaf, a convenient arrangement
is to have cords stretched from end to end of the room, or bars, (usually termed
"horses") at each side of the drying chamber, with more or less of a passage-
way between, on which cords or bars, clusters or bunches of the tobacco leaf
to be dried may be suspended, on the method ordinarily adopted in the drying
rooms hitherto usually employed for tobacco drying; and a similar arrangement
is also suitable for the drying of cloths.
When my improved apparatus is employed for baking purposes, no specially
arranged ventilation is necessary in connection with the drying chamber; but

page_text: when employed for the drying of any damp material, one or more ventilators
may be employed, either in the roof, or preferably in the walls and near the floor
level of the drying chamber, to provide for the. escape of a proportion of the moist
air therefrom; and in order that these ventilators may work efficiently, doors
are constructed in the casing of the air heater, to admit an equivalent amount
of fresh air to the circulating current passing through same.
The heater which I preferably employ is the air heating apparatus described
in the Specification of Letters Patent granted to me and dated 28th September
1895, No. 18167 but I do not limit myself to this particular form of heater; and
when I employ this apparatus I enclose it in a casing fitted with the upward
flowing and basement return air flues herein before referred to as connecting the
heater with the drying chamber.
When the drying chamber is above the heater chamber, and is fitted with
racks and trays of foraminous material, it is convenient to have the building
constructed with an ante-room to both the heater and drying chambers, for
handling the material to be dealt with, and to have the racks arranged on opposite
sides of the drying chamber, with the entrance door at one side, and windows
for light at the other ends, and also with small doors in the side walls, through
which the material on the trays or on the suspending cords or bars may be
inspected from the adjoining ante-room by the attendant from time to time, to
ascertain its condition and progress, without his having to go into the drying
chamber to do so; and in order that the attendant may more conveniently reach
the highest of the shelves in the drying chamber to insert or withdraw the trays,
or to hang the material to be dried on the highest cords or bars, a platform con-
structed preferably of iron, is provided between the racks, but not extending
underneath them, and about two feet above the solid floor of the room, and I
locate the air flue or air flues for admitting the hot air from the heater, about
the centre of the room, and underneath this platform, when the drying chamber
is above the heater chamber; or in the upper part of one of the end walls when
the chambers are side by side, so that in the former case the inflowing air shall
strike against the underside of the platform and be thereby deflected under the
racks of trays. I preferably carry the return flues back to the heater, from near
the ends of the room, and pass them down through the iron platform and floor
of the room to the base of the heater, so that the return air may be drawn down
from near the surface of this platform, and also from each end of the room; but
when the heater and drying chambers are side by side I preferably admit the
inflowing hot air close to the ceiling from whence it descends through the material
to return ducts below the same leading to the base of the heater. In order that
the return flow of cool air to the heater may be equal over the whole tray area,
perforated plates are placed under the tray racks nearest the two return air flues 4
having their perforations increased as shown in the drawings so that the plates
with the smallest area of perforations shall be nearest that part where the return
suction is greatest.
Some of the advantages arising from the employment of my herein described im-
proved drying or baking apparatus, are that a large amount of material can be 4
uniformly dried or baked at one time, and by reason of the circulating current,
the required heat is very equably maintained in all parts of the drying chamber,
and at any temperature suitable for the material to be dried, up to as high as
250 or 300 degrees; and by the employment of an economical air heating appar-
atus such as hereinbefore referred to, the work to be done is accomplished with 5
great economy of fuel.
Reference to the accompanying drawings will more fully explain the nature
of my invention and how same is carried into effect:
Figure 1 is a sectional elevation on line 1-1 of Figure 2 of an improved
drying apparatus constructed according to this invention, with the heater 55
situated below the drying chamber.
Figure 2 is a sectional plan of the same on line 2-2 of Figure 1

page_text: Figure 3 is a sectional elevation of the same on line 3-3 of Figure 2.
Figures 4, 5 and 6, illustrate an apparatus constructed according to my inven-
tion with the heater and drying chamber placed side by side; Figure 4 being
a sectional elevation on line 4-4 of Figure 5; Figure 5 a sectional plan on
line 5-5 of Figure 4 and Figure 6 a sectional elevation on line 6-6 of Figure 5.
The same letters indicate the same or corresponding parts in all the figures.
a is the heater chamber, 6 the drying chamber, c the fireproof ceiling, & the
heater, e the air flue conducting the hot air from the heater d to the drying
chamber b; f f¹ are the return air flues conducting the cool air from the drying
chamber b to the heater d, g g are the racks or shelves which support the trays /
of wire web or other foraminous material; is the iron platform, kk are the
doors, the windows and m the smoke chimney; n n (Figs. 5 and 6) are perforated
plates to regulate the flow of the return air.
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: -
1. In apparatus for drying tea or tobacco leaves, coffee, fruits, cloths, and
other substances, or for baking tobacco stems, tea and other substances, the
combination of an air heating apparatus, a drying room or chamber, and flow and
return air flues or ducts connecting the said drying chamber with the said air
heating apparatus, whereby the heated air is conducted from the said air heating
apparatus into the said drying chamber, and back into the base of the said air
heating apparatus, and a circulation of heated air thereby maintained through
the said drying chamber, the flow and return currents being self-acting owing
to the flow being relatively hotter than the return current, all substantially as
hereinbefore described and shown.
2. In apparatus for drying tea or tobacco leaves, coffee, fruits, cloths, and
other substances or for baking tobacco stems, tea and other substances, the
combination of an air heating apparatus, a drying room or chamber, flow and
return air flues connecting the said drying chamber with the said air heating
apparatus, whereby the heated air is conducted from said air heating apparatus
into the said drying chamber, and back into the base of the said air heating
apparatus, and a circulation of heated air thereby maintained in and through
said drying chamber, and means for mechanically accelerating the circulation of
the flow and return currents, all substantially as hereinbefore described and
shown.
3. The general combination and arrangement of parts constituting an im-
proved apparatus for drying tea or tobacco leaves, coffee, fruits, cloths, and other
substances, or for the baking of tobacco stems, tea, and other substances, all
substantially as hereinbefore described and represented in the accompanying
drawings.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London,
Chartered Patent Agents.