Improvements in Apparatus for Withering and Desiccating the Leaves of Tea or other Plants or Materials.
Year: 1885

page_text: Improvements in Apparatus for Withering and Desiccating the
Leaves of Tea or other Plants or Materials.
I, JOHN. BROWN, of 113 Cannon Street, in the City of London, Engineer, do
hereby declare the nature of my said invention for IMPROVEMENTS IN APPARATUS
86
FOR WITHERING AND DESICCATING THE LEAVES OF TEA OR OTHER PLANTS OR
MATERIALS," to be as follows:-
My invention relates to heating apparatus by which the leaves of the tea plant,
and coffee or cocoa beans, or other material, may be dried, withered, or desiccated,
in a simple, cheap and economical manner.
My apparatus consists of an air heating dovice, in combination with a desiccating
chamber. The air heating device contains an ordinary furnace and grate, from
which the products of combustion are led backwards and forwards through a series
of horizontal tubes connecting smoke chambers, on either side of the casing, and
thence passing away through an independent smoke stack. The air to be heated
enters through a side door of the casing above the furnace, and is caused to pass,
by the filling of the interstices between the tubes, under each horizontal series of
fire tubes, backwards and forwards from side to side of the air heating chamber,
from the bottom to the top or vice versa. The air so heated is led into the top of
the desiccating chamber and drawn downwards through the trays containing the
material to be desiccated, by an artificial draught.
The trays are conveniently arranged in two horizontal layers, supported upon
angle iron bearers or rails, at the widest part of the chamber, so as to expose the
largest possible area to desiccation. Transverse partitions are used between the
two layers of trays, so as to ensure the hot air passing vertically downward through
both layers of trays by the artificial draught.
This draught is conveniently produced by the exhaust of the fire in the furnace,
the communication being made between the bottom of the desiccating chamber
and the ashpan, which is otherwise closed.
I may, alternatively, use any other mechanical means, such as a blower or
centrifugal fan, for producing the artificial draught, in both cases the hot air being
drawn downwards through the trays containing the material to be desiccated.
Owing to the independent construction of the air heater and the desiccating
chamber, the former may be placed outside the building containing the latter, or
they may both be placed in separate rooms.
The trays are passed continuously from end to end of the desiccating chamber
traversing its length twice, and it is found by practice that with a suitable
temperature of air this suffices for the proper desiccation of tea leaves &c.
.
FELL & WILDING,
Agents for the Applicant.

page_text: Improvements in Apparatus for Withering and Desiccating the
Leaves of Tea or other Plants or Materials.
I, JOHN BROWN, of 113 Cannon Street, in the City of London, 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:--
My invention relates to heating apparatus by which the leaves of the tea-plant,
and coffee or cocoa beans, or other material, may be dried, withered, or desiccated
in a simple, cheap, and economical manner.
In order that my invention may be the better understood, I now proceed to
describe the same in relation to the drawings hereunto annexed, reference being
had to the letters and figures marked thereon.
Figure 1 is a vertical transverse section through my combined air-heater and
desiccating or drying chamber.
Figure 2 is another vertical section through the air heating device, through the
line XY, at right angles to the section in figure 1.
Figure 3 is a vertical section through the drying, withering, or desiccating
chamber through the line W Z, at right angles to the former section in figure 1.
Like letters refer to like parts in the different figures.
My apparatus consists, first, of an air heating device which is as follows:-
A is the grate, on which fuel of any suitable kind is burnt, by the supply of air
from under the grate, preferably introduced through the tube B, as hereinafter
more fully described.
The fire grate, fire tubes, and smoke chambers are contained in a casing F,
conveniently square in shape.
The products of combustion generated in the said fire grate A are caused by the
overhead crown plate C to pass up the flue D, which is suitably lined with fire
brick; thence through the series of cross tubes E E E to the opposite side of the
casing F to the smoke chamber G; thence passing back through the series of
tubes H to the opposite smoke chamber K; and thence, passing by any desired
number of zigzag transverses through successive series of fire tubes L M, the
gaseous products of combustion and smoke issue eventually at any convenient
chimney stack N.
These successive smoke chambers G K P are provided with soot doors, internally
lined with fire clay, to allow the tubes to be readily swept. These soot chambers
are formed by vertical partitions QQ and horizontal partitions qq.
The cold air from the external atmosphere, which it is desired to raise to a high
temperature for drying, withering or desiccating purposes, is admitted by a suitable
air door R (figure 1) into the chambers a, b, c, d, which contain the aforesaid
tubes E H L M carrying the products of combustion backwards and forwards
through the said chambers.
Each row of these heating tubes is united by intermediate packing pieces into a
horizontal baffle plate, the ends of the baffle plates being left open alternately at
each end of the combustion chamber, to allow the passage of the atmospheric
- air, which it is desired to heat. The air, then, following the arrows, traverses the

page_text: chamber, a, at the under side of the tubes E, returning through the next chamber, b,
under the tubes H; thence through the successive chambers c, d, till it issues,
raised to a high temperature, through the pipes e, f, into the top of the drying or
desiccating chamber S over the trays T.
This chamber S the second part of my apparatus, is conveniently of such a form
as shown, so as to offer the largest possible drying or desiccating area to the
material, such as tea leaves, passed through it on the movable trays T T. These
trays may be conveniently arranged in two layers, closely under one another, so
that the desiccating effect of the heated air, entering from the flue f, and passing
downward through the perforated trays to the exit B at the bottom of the
chamber, may be uniform upon the material in both sets of trays. It is most
essential for the due and uniform heating effect of the air current that it should be
downward and not upward through the material to be desiccated. The trays may
be alternatively mounted upon a travelling chain or creeper, so that their feed and
travel may be made automatically continuous by driving the same.
The trays T may be of any convenient construction, so long as they are provided
with a perforated or porous floor, upon which the tea leaves or other material to be
desiccated is spread, and through which the hot air may readily pass. The trays
are conveniently mounted upon the angle iron bearers or rails t, the space between.
the trays being closed at each end to prevent the admission of air, and they are
formed conveniently from a series of independent trays of comparatively small
dimensions, so that they can be readily handled for introduction or removal from
the desiccating chamber.
Transverse diaphragms V, V, are provided across the space between the trays to
oblige the downward current of hot air to pass perpendicularly through the two
sets of trays.
1
I find from practice that if trays are being supplied with tea leaves to be
desiccated, by an attendant at one end of the desiccating chamber S, and the heated
trays are being similarly removed, as they are pushed out by the feed, at the other
end by another attendant, that the time occupied by the trays in travelling first on
the lower layer from one end of my desiccating chamber to the other and then in
returning again on the upper layer, is just sufficient, with the proper temperature
of heated air, to produce the required desiccation. The bottom of the chamber S is
made towards the centre, so as to collect into a receptacle the dust that may fall
through the perforated trays.
The circulation of atmospheric air through the air door R, and thence through
the air heater, and downwards through the desiccator S, is conveniently produced
by the exhaust draught of the fire which induces a current through the pipe B into
the ashpan from the desiccating chamber.
I may, however, should I find it necessary, use any convenient artificial means,
such as a centrifugal fan or a blower, to produce the required circulation of the air.
through the desiccating chamber, the downward direction of the hot air current
being maintained.
It may be noted, that as the products of combustion are kept quite apart and
distinct from the air that is being heated for desiccating purposes, and are finally
delivered into an independent smoke stack N, there is no possible communication
between the products of combustion or the smoke and the material to be dried in
the desiccating chamber. Further, my heating apparatus may be conveniently
placed in the open air outside the house in which the desiccating process is being
carried on, or may be contained in distinct and separate rooms or chambers of the
house, the inter-communication being only through the pipes fƒ and B.
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
1st The combination of a multitubular air heating apparatus provided with a
separate chimney stack with a desiccating chamber distinct from the air heater

page_text: through which a circulation of air to be heated is maintained and caused to pass
downwards through the desiccating chamber by the natural draught of the fire
or other means, substantially as described.
2nd In such an air heating apparatus, the construction of the flues in the form of
a horizontal series of tubes, connecting smoke boxes, the hot gases of combustion
passing from opposite end to end in alternate series of tubes; and eventually
issuing from a separate smoke stack, whilst the air at the same time is caused by
the closing of the interstices of the said fire tubes, to pass back wards and forwards
under each horizontal series of fire tubes, before issuing into the top of the
desiccating chamber, substantially as described.
3rd In such a desiccating chamber the construction as shown in figure 3 to give
greater area of desiccation and the mounting of the trays upon rails or otherwise
therein, so as to allow the feed and withdrawal of the trays to be continuous from
end to end of the chamber, substantially as described.
Dated this 10th dore of October 1985
FELL & WILDING,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicant.