Improvements in Apparatus for Drying Tea, Coffee, Cocoa, Cinchona, Hops, Sliced Fruits, Seeds, Meal, or other such Substances, and for Withering Tea.
Year: 1888

page_text: PROVISIONAL DIUIFICATION.
Improvements in Apparatus for Drying Tea, Coffee, Cocoa, Cinchona,
Hops, Sliced Fruits, Seeds, Meal, or other such Substances, and
for Withering Tea.
I, SAMUEL CLELAND DAVIDSON of Sirocco Works, Belfast, Ireland, Merchant,
do hereby declare the nature of this invention to be as follows:-
The object of the improvements is the construction of an apparatus in which a very
strong current of heated air, or cool desiccated air can be used for rapidly drying tea,
coffee, cocoa, cinchona, hops, sliced fruits, seeds, meal, or other such substances, on
sieves or perforated trays arranged in a drying chamber, one above the other in a
vertical column, and moveable in successive order of rotation from bottom to top of
the column, without the material being whirled by the strength of the current into
heaps on the trays while in the drying chamber, or blown away off them by it when
apparatus.
the trays are being put into or taken out of the
The improved apparatus consists of a rectangular drying chamber, fitted with an
inlet port in the top end of it for admitting the heated or desiccated air, and an
outlet or exhaust port for its exit at the lower end, the course of the air current being
thereby directed from top to bottom of the drying chamber. Between these inlet and
outlet ports the drying chamber is arranged to contain a column of superimposed
sieves or perforated trays on which the material to be dried is placed, and which are
capable of being moved upwards one after the other in successive rotation from
bottom to top of the column, and therefore, in a contrary direction to the course of
the air current. These sieves or trays may be arranged on ledges inside the drying
chamber like drawers one above the other, each having an opening for itself in the
side of the drying chamber, by which it can be inserted or withdrawn. With this
arrangement of the trays their movement in successive rotation from bottom to top of
the column is effected by withdrawing the top tray, then moving the next below it
into its place; then No. 3 to the place of No. 2, and so on to the bottom tray, which
when drawn out from the lowest place, and put into the one above it, leaves the bottom
space vacant, into which the fresh tray is then put.

page_text: But the drying chamber is preferably so constructed that the trays may all be
simultaneously moved up in a pile, one on top of the other by a lift arrangement
fitted in the base of the drying chamber, which is preferably operated by a combination
of levers, links and cranks or cams, motion being imparted to same by a lever
operated either directly by the attendant in charge of the machine, or by being so
connected to the door of the tray ports which are hereinafter referred to, that the
shutting or opening of the door raises or lowers the lift.
Opposite the top and bottom trays of the column, the drying chamber is fitted with
doorways which may be called "tray ports" for inserting the bottom tray or with-
drawing the top one. On the bottom tray being inserted, it is then raised by the lift
to a sufficient height to allow another tray to slide freely in below it, in which
position it is then caught by four pawls, which hold it suspended when the lift is
lowered down to its original position. Another tray is then passed in through the
tray port, and on the lift being again raised, the new tray pushes the previous one up
in front of it, and on being caught by the pawls, as the first one was, it is held up by
them with the upper tray resting on top of it. This operation is then repeated until
the top tray comes opposite the upper tray port, through which it can be then with-
drawn when the material on it is found to be sufficiently dry. Both these tray ports
are fitted with doors which are kept closed after inserting or withdrawing the trays,
in order to prevent the passage of air through them into or from the drying
chamber.
The air current down through the trays may be produced by pressure blast, with
fans or other suitable blowing apparatus, and on being driven into the air space above
the top tray it will of course find its way down through the trays to the outlet port.
But the current is preferably produced down through the trays by exhausting the air
from below the bottom trays by means of an exhaust fan or pump, or a powerful
chimney draft connected to the outlet port. The air may be heated by any air
heating appliances such as steam-pipes, or pipes heated directly by fire, but there is
preferably used for this purpose the air heating stove described in specification
No. 4773 of 1877 and now generally known as the "Sirocco " Air Heating stoves.
Or, cool desiccated air may be used, and its desiccation may be effected by any
suitable desiccating operation, such as passing it over dry chloride of lime before.
being admitted to the drying chamber.
The course of the air current being down through the trays from top to bottom of
the drying chamber it is obvious that no matter how strong the current may be, it
cannot disturb or blow the material about on the trays, while they are in proper
position within the drying chamber, as the stronger the current, the more firmly is
the material held in its place on the trays; whereas; were the current upwards
through the trays it would lift the material, or whirl it about into heaps upon them.
But while the trays are being inserted or withdrawn, there is such a strong in-draft
through the bottom tray port when the air current is being created by an exhaust
from below the bottom tray, or out draft through the top tray port when it is created
by a pressure-blast delivered above top tray, that unless the air current be checked
during the time that the trays are being put into or taken out of the apparatus, the
rush of air through the open tray ports would be so strong inwards or outwards, as
the case may be, that the material on the trays would be blown away off them. To
effect a temporary modification of the air current, whether same be created by exhaust
or pressure blast, the exhaust outlet, or the pressure blast inlet, as the case may be,
is according to this invention fitted with an air valve, such for instance, as a louvre or
grid-iron valve which may either be operated directly by an attendant or by being so
connected to the doors of the tray ports, that the opening of these doors closes the
air valve, which sufficiently modifies or if necessary practically stops the air draft, so
that during the time the trays are being put into, or taken out of the apparatus, there
is little or no rush of air through the open tray ports, and consequently, no blowing
away of the material off the trays, and the shutting of these doors opens the valve
again, and allows the full air draft to operate through the trays as before.
To facilitate the removal of all the trays from the drying chamber, a door may be

page_text: provided between the top and bottom tray ports, which, when opened, allows of the
removal of the intermediate trays between top and bottom of the column.
From the foregoing description it will be seen that the improved apparatus
constitutes what may properly be called a
Down Draft Sirocco."
::
When being used for drying tea on tea estates, the air from the exhaust port of the
drying chamber may be led into another similarly constructed drying chamber, and
driven down through the trays in it for the purpose of limping or withering tea leaf
in its green state as the moderate temperature of the exhaust air is very suitable for
this purpose, or it may be led into an air duct the top of which is closed by perforated
plates, over which one or more rows of sieves or perforated trays are so arranged
that the air issuing from the air duct shall pass up through the trays, and in so doing,
limp or wither the green leaf, and thereby sufficiently prepare it for the rolling
process.
Ր antamba 1888

page_text: Improvements in Apparatus for Drying Tea, Coffee, Cocoa, Cinchona.
Hops, Sliced Fruits, Seeds, Meal, or other such Substances, and
for Withering Tea.
1. SAMUEL CLELAND DAVIDSON of Sirocco 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:-
The object of the improvements is the construction of an apparatus in which a
very strong current of heated air, or cool desiccated air, can be used for rapidly
drying tea, coffee, cocoa cinchona, hops, sliced fruits, seeds, meal, or other such
substances on sieves or perforated trays arranged in a drying chamber, one above the
other in a vertical column, and movable in successive order of rotation from bottom
to top of the column, without the material being whirled by the strength of the
current into heaps on the trays while in the drying chamber, or blown away off them
by it when the trays are being put into or taken out of the apparatus.
The improved apparatus consists of a rectangular drying chamber, fitted with an
inlet port in the top end of it for admitting the heated or desiccated air, and an
outlet or exhaust port for its exit at the lower end, the course of the air current being
thereby directed from top to bottom of the drying chamber. Between these inlet and
outlet ports the drying chamber is arranged to contain a column of superimposed
sieves or perforated trays on which the material to be dried is placed, and which are
capable of being moved upwards, one after the other in successive rotation from
bottom to top of the column, and therefore in a contrary direction to the course of
the air current. These sieves or trays may be arranged on ledges inside the drying
chamber like drawers one above the other, each having an opening for itself in the
side of the drying chamber, by which it can be inserted or withdrawn. With this
arrangement of the trays their movement in successive rotation from bottom to top of
the column is effected by withdrawing the top tray, then moving the next below it
into its place; then No. 3 to the place of No. 2, and so on to the bottom tray which,
when drawn out from the lowest place, and put into the one above it, leaves the bottom
space vacant into which the fresh tray is then put.
But the drying chamber is preferably so constructed that the trays may all be
simultaneously moved up in a pile, one on top of the other by a lift arrangement
fitted in the base of the drying chamber, which is preferably operated by an arrange-
ment of levers and vertically sliding bolts, motion being imparted to same by a lever,
operated either directly by the attendant in charge of the machine or by being so
connected to the door of the tray ports, which are hereinafter referred to, that the
shutting or opening of the door raises or lowers the lift.
Opposite the top and bottom trays of the column the drying chamber is fitted with
doorways, which may be called "tray ports," for inserting the bottom tray or with-
drawing the top one. On the bottom tray being inserted, it is then raised by the lift
to a sufficient height to allow another tray to slide freely in below it, in which position
it is then caught by four pawls, which hold it suspended when the lift is lowered
down to its original position. Another tray is then passed in through the tray port,
and on the lift being again raised, the new tray pushes the previous one up in front of

page_text: it, and, on being caught by the pawls as the first one was, it is held up by them with
the upper tray resting on top of it. This operation is then repeated until the top
tray comes opposite the upper tray port, through which it can be then withdrawn
when the material on it is found to be sufficiently dry. Both these tray ports are
fitted with doors which are kept closed after inserting or withdrawing the trays, in
order to prevent the passage of air through them into or from the drying chamber.
The air current down through the trays may be produced by pressure blast, with
fans, or other suitable blowing apparatus, and on being driven into the air space above
the top tray, it will of course find its way down through the trays to the outlet port.
But the current is preferably produced down through the trays by exhausting the
air from below the bottom trays by means of an exhaust fan or pump, or a powerful
chimney draft connected to the outlet port. The air may be heated by any air
heating appliances, such as steam pipes, or pipes heated directly by fire, but there is
preferably used for this purpose the air heating stove described in specification No. 4773
of 1877, and now generally known as the Sirocco " Air Heating stove. Or, cool,
desiccated air may be used, and its desiccation may be effected by any suitable
desiccating operation, such as passing it over dry chloride of lime before being
admitted to the drying chamber.
The course of the air current being down through the trays from top to bottom of
the drying chamber, it is obvious that no matter how strong the current may be, it
cannot disturb or blow the material about on the trays, while they are in proper
position within the drying chamber, as the stronger the current, the more firmly is the
material held in its place on the trays; whereas, were the current upwards through
the trays, it would lift the material, or whirl it about into heaps upon them. But
while the trays are being inserted or withdrawn there is such a strong in-draft through
the bottom tray port when the air current is being created by an exhaust from below
the bottom tray, or out draft through the top tray port when it is created by a pressure
blast delivered above top tray, that, unless the air current be checked during the
time that the trays are being put into or taken out of the apparatus, the rush of air
through the open tray ports would be so strong inwards or outwards, as the case may
be, that the material on the trays would be blown away off them. To effect a
temporary modification of the air current, whether same be created by exhaust or
pressure blast, the exhaust outlet or the pressure blast inlet, as the case may be, is,
according to this invention fitted with an air valve, such for instance, as a louvre, or
gridiron valve which may either be operated directly by an attendant, or by being so
connected to the doors of the tray ports, that the opening of these doors closes the
air valve, which sufficiently modifies, or if necessary practically stops the air-draft, so
that during the time the trays are being put into or taken out of the apparatus, there
is little or no rush of air through the open tray ports, and consequently, no blowing
away of the material off the trays, and the shutting of these doors opens the valve
again, and allows the full air draft to operate through the trays as before.
To facilitate the removal of all the trays from the drying chamber, a door may be
provided between the top and bottom tray ports, which, when opened, allows of the
removal of the intermediate trays between top and bottom of the column.
From the foregoing description it will be seen that the improved apparatus
constitutes what may properly be called a "Down Draft Sirocco."
When being used for drying tea on tea estates, the air from the exhaust port of the
drying chamber may be led into another similarly constructed drying chamber, and
driven down through the trays in it for the purpose of limping or withering tea leaf
in its green state, as the moderate temperature of the exhaust air is very suitable for
this purpose, or it may be led into an air duct the top of which is closed by perforated
plates, over which one or more rows of sieves or perforated trays are so arranged
that the air issuing from the air duct shall pass up through the trays, and in so doing,
limp or wither the green leaf, and thereby sufficiently prepare it for the rolling
process or the perforated plates and sieves or perforated trays may be arranged so
that the air from the air-duct shall pass down through them instead of passing up as
just described, or the arrangement may be such that some of the air may pass up

page_text: through perforated plates and sieves and some down through other sieves and
perforated plates.
The accompanying drawings illustrate the construction of the apparatus.
Figure 1 is a vertical section through the drying chamber from front to back,
showing it with the perforated trays arranged to slide in and out like drawers, and
fitted with a grid-iron valve for closing and opening the exhaust air port below the
trays.
Figure 2 is a vertical section of the same apparatus as shown in Figure 1, but at
right angles to the sectional line of same, showing position of the air valve in the
apparatus when being worked with the air current driven under pressure into top of
drying chamber instead of being exhausted from below the trays, as in Figure 1.
Figure 3 is a similar section to Figure 1, but represents the drying chamber
arranged for the perforated trays or sieves being elevated in a column from bottom to
top of the apparatus by a lifting appliance fitted below the trays, and with the air
valve for closing the air exhaust port, so connected, with this lifting appliance, that
the operation of the lift opens and closes the air valve, and at the same time closes or
opens the door of the lower tray port for inlet of fresh trays.
Figure 4 is another vertical section of the same apparatus as shown in Figure 3,
but at right angles to the sectional line of same, and more fully illustrates the
construction and operation of the lift for elevating the trays, and also the pawls for
catching and holding the trays suspended, and the air exhaust port fitted with an
exhaust fan. But, as already mentioned the air exhaust may be created by any form
of fan or air pump, or by chimney draft.
Figure 5 is a perspective elevation of the same apparatus as shown in Figures 3
and 4, illustrating how it may be connected with the "Sirocco " Air Heating stove
described in the specification of previous Letters Patent granted to me and dated
15th Dec. 1877, No. 4773.
The arrows shown in each figure indicate the course and direction of the air-
current. The letters employed to indicate the various different parts of the apparatus
represent the same individual parts in each figure and are as follows :-
A. The drying chamber.
B. The inlet port for the heated or desiccated air.
C. The outlet or exhaust air port.
D. Gridiron valve controlling the passage of the air through the exhaust port.
D2. Alternative position of gridiron valve. controlling the entrance of the air
through the inlet port to the top of the drying chamber.
E. Lever operating the gridiron valve in Figures 1 and 2.
F. Bell crank connection for operating the gridiron valve D of the exhaust air port
by the movement of the tray lift in Figures 3 and 4.
F. Connecting rod from lower end of one of the bars L, to hell crank F.
G. Lever operating tray lift in Figures 4 and 5.
G. Catch and segment for holding lever G in the required positions.
H. Spindle or shaft operated by lever G.
J. Beam levers fitted with spindle H, one end acting directly on the bars or bolts
for lifting the trays, and the other end connected to the beam levers K.
K. Beam levers connected to the beam levers J for operating the opposite pair of
bars or bolts for lifting the trays.
L. Bars' or bolts with vertical movement for lifting the trays.
M. Pawls for holding the trays suspended, and constructed to drop in by their own
weight below the trays when elevated by the lift clear of the pawls.
M. Vertical section of an alternative arrangement of the pawls operated by springs
to project them below the trays in cases where their own weight is not considered
sufficient for this purpose.
M. Horizontal section of Mr.
N. Angle iron rails or slides for supporting trays.
N. Angle iron stopper for preventing trays being lifted past the upper tray
Dort R.

page_text: over it.
S³. Alternative arrangement of the air-duct S³ for the air draft to pass down
through the trays.
S. Perforated plate for distributing the air draft.
T. Perforated trays or sieves.
U. Carriers on top of trays for supporting the trays above them.
V. Door for removal when necessary, of the intermediate trays between upper and
lower tray ports.
W. Door for getting into base of drying chamber.
X. Thermometer.
X². Handle of throttle valve for cutting off air supply.
Y. Door for admitting cold air into the air supply duct to reduce temperature of
air current when necessary.
Z. Sirocco Air Heating Stove.
Although the withering apparatus is shown only as connected with the drying
apparatus shown in Figure 2 it is evident that it can be applied in connection with
the other modifications of drying apparatus shown in the drawings.
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. An apparatus for drying tea, coffee, cocoa, cinchona, hops, sliced fruits seeds,
meal, or other such substances, in which the drying of the material is effected by a
down draft or current of heated or desiccated air through a drying chamber containing
superimposed sieves or perforated trays for carrying the material upon, and in which
drying chamber valves or other suitable arrangements are employed for temporarily
checking or diminishing this air draft or current, while any of the trays are being
inserted or withdrawn from the apparatus, substantially as set forth.
2. The combination of a lifting appliance or arrangement whereby the trays are
moved in rotation order from bottom to top of the drying chamber, of pawls, or
equivalent devices for holding the trays suspended, and of a damper or air valve on
the inlet or exhaust ports for checking or moderating the air draft while the trays are
being inserted or removed from the drying chamber, substantially as set forth.
3. The combination with the drying chamber, of a chamber or air duct for withering
green tea leaf by means of the air from the exhaust port of the said drying chamber,
substantially as set forth.
4. The several arrangements or combinations of parts as described and shown and
constituting improved apparatus for drying tea, coffee, cocoa, cinchona, hops, sliced
fruits, seeds, meal, or other such substances.