Improvements in Apparatus for Limping or Withering Tea Leaf, or for Drying Vegetable or other Substances.
Year: 1895

page_text: Date of Application, 18th Nov., 1895-Accepted, 4th Jan., 1896
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COMPLETE SPECIFICATION.
f
:
Improvements in Apparatus for Limping or Withering Tea Leaf, or
for Drying Vegetable or other Substances.
:
I
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
insand by the following statement:―
i
"The invention refers more particularly to the apparatus described in the
Specification of previous Letters Patent granted to me and' dated 11th March
1895 No. 5123 (which for brevity of description is hereinafter referred to as the
previous Specification). In the practical working of the apparatus difficulty 'ha's
been experienced'in accomplishing the discharge of the contents of the revolving
drum through the discharge doors by means only of the revolving motion of the
drum after the said doors are opened, the last part of its contents having usually to
he taken out by hand, after stopping the machine; further when light material
such as tea leaf is being dealt with, there has also been a 'tendency for the same to
drift over with the current of air passing through the drum, from the air inlet at
the one end towards the exhaust at the other end. The object of the hereinafter
described invention is to remedy and obviate these difficulties.
The improvements for effecting the complete discharge of the leaf by means only
of the revolving motion of the drum, after the discharge doors are opened, consist
in having the said doors which are constructed in the side of the revolving drum so
hinged as to drop inwards upon supporting brackets attached to the ends of the
drum or its divisional diaphragms or discs and secured thereto by side bolts or
other suitable fastenings so as to form a ledge or shelf which projects considerably
further towards the centre of the drum than the stationary shelves which are fitted
to its interior circumference, as described in the previous Specification, whereby as
the drum revolves this projecting shelf formed by the door collects the tea leaf or
other material, upon the side which then faces the open doorway or port. The
angle or inclination of the projecting shelf is so arranged that it shoots the
material that falls in front of it, when on the ascending side of the drum; out
through the door-way. One of the shelves which are described' in the previous
Specification as fitted to the inuer circumference of the drum, is attached to the
inner face and edge of the hinged door itself (and another may also be attached at
or near the opposite-edge and near the hinges) so that when the door is opened
inwards the said shelf being attached thereto goes with it' towards the interior of
the drum and its obstructive action to the material sliding forwards along the
interior surface of the drum towards the open door-way or port is thereby
removed.
The improvements for preventing the leaf or other material which is being
treated in the drum, from drifting with the air current from the air inlet end of' the
drum towards the exhaust end, consist in the employment of one or more discs or
diaphragms of preferably about three-fourths the diameter of the drum centrally
suspended: inside, at right angles to the line of its axis, leaving the space between
their outer edges and the interior sides of the drum open for passage of the air
current,; or the interior of the drum may be divided into two or more compartments
by divisional diaphragms or walls; the central portion of which for about two-thirds
7

page_text: '
or three-fourths of their diameter may be solid, and the remaining outer part of it
be perforated or made of wire netting or other foraminous material. This
arrangement and construction of the said discs or diaphragms prevents the air from
flowing in a direct line from the inlet port in the one end of the drum to the outlet
port in the other, and guides it as an annular current along the inner circumference
of the drum, so that the circulating current of air flowing through and through the
drum has still a sufficiently free passage from the inlet to the outlet opening, and
its direction being along the sides of the drum and not through its centre, it does
not impinge against the material during the time it is falling down from the lifting
shelves when the drum is revolving; it therefore has no tendency to drift forward
with the current and unduly accumulate as heretofore in the exhaust end. By
having the drum thus arranged in separate compartments, each compartment can
be charged with material in successive rotation, so that the limping or withering or
drying of one charge may be completed ahead of the next. This is more
particularly desirable in the limping or withering of tea leaf as each of the
compartments can be made of sufficient size to hold a full charge of leaf for a
rolling machine, so that when one charge is fully limped or withered and turned
out of the machine, and is subsequently being rolled, the leaf in the next
compartment will be getting finished and ready for discharge, whereas if a
quantity equal to three or four charges of a rolling machine were all limped or
withered and discharged at one time, and only part of it could be rolled right off,
the balance which would have to remain waiting would get more or less chilled and
hard in texture, and not be in so good a condition for rolling as if taken freshly on
its discharge from the drum.
Reference to the accompanying drawings will more fully explain the nature of
the invention.
Figure 1 is a plan of the general arrangement of apparatus described in the
previous Specification with the present improvements applied thereto.
Figure 2 is a front elevation of the same, with the rotating cylinder or drum in
central longitudinal section.
Figures 3 and 4 are cross sections through the drum, Figure 3 showing the door
in the side with two shelves attached thereon, closed, and Figure 4 the door
and its two attached shelves, opened inwards and resting on its supporting
brackets.
Figure 5 is a sectional plan of the drum taken through line a b of Figure 4.
A is the horizontal rotating cylinder or drum as described in the previous
Specification, B B are the standards upon which it is-mounted. C is the air
inlet port at one end and D the air outlet port at the other end of the drum.
E is the air heating apparatus and F the fan, C¹ is the inflow air conduit pipe
leading from the fan F to the air inlet port C; D' is the return air conduit tube
leading from the air outlet port D to the air heating apparatus E. E' is an air
conduit funnel or tube leading from the air heating apparatus E to the fan F.
L L are the new improved hinged doors in the side of the revolving drum A with
side bolts L' mounted thereon. M M are longitudinal ledges or shelves fitted to
the inner circumference of the drum A and to the inner side of the doors I.
NN are discs, diaphragms, or divisional walls at right angles to the line of axis
of the revolving drum A; the central portion of these discs is solid, and the
remaining outer part N¹ is either open-spaced for air passage between the bars or
spokes suspending the discs N from the inner circumference of the drum, or is, the
continuation of the same in the form of perforated plates, wire web, or other
suitable foraminous material. 00 are supporting brackets or pins attached to
the ends of the drum A or to the divisional diaphragms or discs N. P is a steam
engine employed to drive the fan F and the drum, and which by passing its
exhaust steam through the tubes of the air heater E, imparts sufficient heat
thereto for the working of the apparatus.
When employing the machine for the
•
limping or withering of tea leaf the

page_text: doors L are opened inwards so as to rest upon the supporting brackets or pins O.
The leaf to be treated is supplied to the drum A'through the opened doorway or
port the doors L are then closed up in line with the circumference of the drum,
and kept shut by means of the side boits L'; the drum and fan are then caused
to revolve by means of belting or other gearing from the engine P, the fan F
drawing hot air from the air heater, and passing it into the drum and through
the open space or foraminous material N', forming a portion of the diaphragms or
divisional walls N, and back through the air heater, thereby causing a continuous
circulation of the hot air through the drum and air heater. The horizontal
shelves M inside the drum A cause the leaf to rise a short distance up the sides
and fall therefrom into the bottom of the drum, to ensure the whole of the charge
of leaf being equally treated by the hot air current passing through the drum A,
and as the leaf drops off the shelves, the solid central part N of the diaphragms
or divisional walls, prevents the air current through the drum impinging against
it, so that it falls straight to the bottom without being drifted along in the
direction of the air exhaust end of the drum.
When the leaf has become sufficiently limped or withered and ready to be
discharged, the rotation of the drum is stopped and the doors L again opened
inwards on to the supporting pins or brackets O, and secured thereto by the side
bolts L', whereby the open doors L'each form deep projecting shelves of sufficient
depth to, upon the door A being once more made to revolve, collect the whole of
the material that is being treated therein upon the side facing the open doorway,
so that when it reaches the lowest point of rotation, the entire contents are
discharged through the open doorway.
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 machines of the type described in the previous Specification, the
employment of an inwardly opening door on the filling and discharge port of the
drum, which can be secured inside the drum at such an angle in respect of
the open doorway or port, that as the drum revolves it causes the contained leaf
to collect in front of it, and discharge through the said doorway or port, all
substantially as hereinbefore described and representel in the accompanying
drawings.
2. In machines of the type described in the previous Specification, the
employment of an inwardly opening door on the filling and discharge port of the
drum, as described in Clain 1, on the back of which door are fitted one or more
of the lifting shelves which are ordinarily attached to the inner circumference of
the drum as described in the previous Specification, so that when the door is
opened inwards the said shelf goes with it, and is thereby removed from its
otherwise normal position on the inner circumference of the drum, so that it no
longer forms an obstruction to the leaf collecting in front of the said door and
discharging therefrom through the open port as the drum revolves, all
substantially as hereinbefore described and represented in the accompanying
drawings.
3. In machines of the type described in the previous Specification, the
employment in the drum of discs or diaphragms placed inside the drum at right
angles to its axis, and having either an open space between their periphery and
the interior circumference of the drum, or if continued out to the interior
circumference of the drum having their outer portion perforated or formed with
wire netting or other foraminous material so as to provide an annular space for
the air current through the drum along its inner circumference, all substantially as
and for the purposes herein before described and represented in the accompanying
drawings.
4. The general arrangement of parts forming the improved apparatus for
limping or withering tea leaf, or for drying vegetable or other substances, all

page_text: substantially as hereinbefore described and represented in the accompanying
drawings:
Dated this 18th day of November 1895.
J.C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, "Chartered Patent Agents.