Improvements in Apparatus for Drying Tea, Coffee, Cocoa, Grain,, or other Substances.
Year: 1897

page_text: Date of Application, 14th July, 1897
Complete Specification Left, 5th Apr., 1898-Accepted, 7th May, 1898
FRUVIDIONAL
DPECIFICATION.
Improvements in Apparatus for Drying Tea, Coffee, Cocoa, Grain,,
or 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 has reference to apparatus for drying tea, coffee, cocoa, grain or
other substances (hereinafter referred to as the material) in which said material to
be dried is carried through the apparatus upon a series of superimposed endless
webs which discharge said material by letting it drop or fall from one web to
another, and my invention more particularly refers to the drying apparatus described
in the Specifications of previous Letters Patent granted to me, and dated
2nd February 1892 No. 2046 and 19th November 1894 No. 22341 (which
Specifications for brevity of description are hereinafter referred to as my previous
Specifications) and the objects amongst others of my invention are to so accomplish
the distribution of the material when it falls from one web to the other that when
the fresh material to be dried is spread to a given thickness of layer on the top
web, and is discharged therefrom to another web below same, the thickness of the
layer upon the lower web can be either increased or decreased as may be desired to
any required extent. In conjunction with my herein described improved arrange-
ments for actuating the webs so as either to attenuate or thicken as the case may
be the layer of material on each succeeding lower endless web. I introduce above
the top surface of the top web the fresh hot air which passes through the material
so that the fresh hot air acts firstly upon the freshly introduced material and passes
through same in a downward direction successively through the lower webs to any
suitable appliance such as a fan for drawing and then exhausting the air current
after having passed through the material on all the webs from top to bottom of.
the apparatus.
In carrying my invention into effect I preferably have the top web so driven that
its speed of travel is relatively faster than that of the web below it which in turn
is relatively faster than that of the next succeeding under web, and so on, and the
method of driving the webs which I preferably adopt is by mounting sprocket
wheels of suitably different diameters one to the other on the ends of the shafts of
cach of the driving drums or sprocket wheels on which the webs are mounted and
round which they revolve or pass, driven by pitch chains engaging said sprocket
wheels, whereby from a given travel of said driving chains, the sprocket wheel of
the top web accomplishes a greater number of complete revolutions than the wheel
below same, and when more than two webs are employed the said lower wheel a
greater number than the next lower wheel; but I do not limit myself to the par-
ticular method of driving the webs herein described as any other suitable method
of driving them may be adopted, whereby the upper webs are caused to move or
travel relatively faster (or slower as may be desired) than those below same, and to
so discharge the material from the upper to the lower webs that the layer on the
surfaces of each succeeding lower web is thereby made deeper or thinner than that
on the web above same, according to whether the speed of the upper webs is
arranged to be faster or slower than the lower ones.

page_text: It will be evident that if the apparatus is arranged to work with the top web
travelling faster than the next succeeding lower web, the layer of material upon the
lower web owing to its slower travel will be increased in thickness, and that if this
second web be travelling faster than the next one below it, the thickness of the layer
of material upon the third web will be further thickened, and an important
advantage in using this arrangement of the apparatus is that for a given number
of webs employed in the apparatus, the material by having a slower travel, and
being thus in thicker layers on the lower webs than on the top one, is retained
longer in the apparatus than if the webs were all travelling at the same speed
throughout and a further important advantage of this system when employed in
conjunction with the apparatus described in my previous Specifications is, that when
(more particularly) tea leaf. is passed into the apparatus in its wet state on to the
top web, the layer is relatively thinner than it subsequently becomes upon the lower
webs, and as tea leaf in its wet state offers more obstruction to the passage of a
current of air through it than when it has become partially dried, it is consequently
desirable to have the layer thin at the first when freshly introduced, and its being
thus exposed in a thin layer to the fresh hot air coming into the drying apparatus
its tendency to further fermentation is instantaneously arrested, which is an
important matter in the production of tea of the best quality; while on falling to
the lower webs after having become partially dried it lies more loosely and openly
on the surface of same, so that the air passes through it freely, and
as the
speed of its travel on the lower webs is slower, while at the same time the high
temperature of the freshly introduced air is somewhat reduced by passing through
the top damp layer, the leaf can be safely exposed without danger of burning for
any length of time desired upon the lower webs, consequently the drying of the
leaf can be safely carried to such an extent that the tea when discharged is not
only perfectly dessicated, but also comparatively cool.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.
Improvements in Apparatus for Drying Tea, Coffee, Cocoa, Grain,
or 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 :-
This invention has reference to apparatus for drying tea, coffee, cocoa, grain or
other substances (hereinafter referred to as the material) in which the material to
be dried is carried through the apparatus upon a series of superimposed endless
webs which discharge the material by letting it drop or fall from one web to
another, and the invention more particularly refers to the drying apparatus described
in the Specifications of previous Letters Patent granted to me, and dated
2nd February 1892 No. 2046 and 19th November 1894 No. 22341 (which
Specifications, for brevity of description, are hereinafter referred to as the previous
Specifications) and the objects amongst others of the invention are to so accomplish
the distribution of the material when it falls from one web to the other that when
the fresh material to be dried is spread to a given thickness of layer on the top
web, and is discharged therefrom to another web below same, the thickness of the

page_text: layer upon the lower web can be either increased or decreased as may be desired to
any required extent. In conjunction with the herein described improved arrange-
ments for actuating the webs so as either to attenuate or thicken as the case may
be the layer of material on each succeeding lower endless web there is introduced
above the top surface of the top web the fresh hot air which passes through
the material, so that the fresh hot air acts firstly upon the freshly intro-
duced material, and passes through same in a downward direction successively
through the lower webs to any suitable appliance such as a fan for drawing and then
exhausting the air current after having passed through the material on all the webs
from top to bottom of the apparatus.
In carrying the invention into effect I have the top web so driven that its speed
of travel is relatively faster than that of the web below it which in turn is relatively
faster than that of the next succeeding under web, and so on, and the method of
driving the webs which is preferably adopted is by mounting sprocket wheels of
Buitably different diameters one to the other on the ends of the shafts
of each of the driving drums or sprocket wheels on which the webs are
mounted and round which they revolve or pass, driven by pitch chains
engaging the said sprocket wheels whereby for a given travel of the driving
chains, the sprocket wheel of the top web accomplishes a greater number
of complete revolutions than the wheel below same, and when more than
two webs are employed the said lower wheel a greater number than the next
lower wheel, but I do not limit myself to the particular method of driving the webs
herein described as any other suitable method of driving them may be adopted,
whereby the upper webs are caused to move or travel relatively faster (or slower as
may be desired) than those below same, and to so discharge the material from the
upper to the lower webs that the layer on the surfaces of each succeeding lower
web is thereby made deeper or thinner than that on the web above same, according
to whether the speed of the upper webs is arranged to be faster or slower than the
lower ones.
It will be evident that if the apparatus is arranged to work with the top web
travelling faster than the next succeeding lower web, the layer of material upon the
lower web owing to its slower travel will be increased in thickness, and that if this
second web be travelling faster than the next one below it, the thickness of the
layer of material upon the third web will be further thickened and an important
advantage in using this arrangement of the apparatus is that, for a given number
of webs employed in the apparatus the material by having a slower travel, and
being thus in thicker layers on the lower webs than on the top one, is retained
longer in the apparatus than if the webs were all travelling at the same speed
throughout, and a further important advantage of this system when employed in
conjunction with the apparatus described in the previous Specifications is, that when
(more particularly) tea leaf is passed into the apparatus in its wet state on the top
web, the layer is relatively thinner than it subsequently becomes upon the lower
webs, and as tea leaf in its wet state offers more obstruction to the passage of a
current of air through it than when it has become partially dried, it is consequently
desirable to have the layer thin at the first when freshly introduced, and its being
thus exposed in a thin layer to the fresh hot air coming into the drying apparatus
its tendency to further fermentation is instantaneously arrested, which is an
important matter in the production of tea of the best quality; while on falling to
the lower webs after having become partially dried, it lies more loosely and openly
on the surface of same, so that the air passes through it freely, and as the speed of
its travel on the lower webs is slower, while at the same time the high temperature
of the freshly introduced air is somewhat reduced by passing through the top
damp layer, the leaf can be safely exposed without danger of burning for any
length of time desired upon the lower webs, consequently the drying of the leaf
can be safely carried to such an extent that the tea when discharged is not only
perfectly dessicated but also comparatively cool.
The accompanying drawings represent an apparatus constructed according to

page_text: the present invention and will enable the same to be fully understood. In these
drawings:-
Figure 1 is a side elevation of the apparatus;
Figure 2 is an end elevation, and
Figure 3 is a plan.
A is a drying chamber of similar construction to that described in the previous
Specifications and through which the endless webs B B1 B2 travel, and which webs
are herein shown are constructed of conveyor chains with tilting trays so mounted
thereon that they drop and discharge the material upon them, in the first
instance on to the next lower returning stretch of the same web and from it on to
the upper stretch of the web next beneath same. The movement of the endless
webs is effected by keying or otherwise securing upon the shafts of their respective
sprocket wheels on which the conveyor chains are mounted around which they
revolve, sprocket wheels C C1, C2 of varying diameter, C in the apparatus
herein shown being the smallest and C2 the largest. These sprocket wheels are
driven by means of pitch chains D, D¹, D² from the sprocket wheels E which are
of equal diameter so that it will be readily understood that the revolutions per
minute of the lower sprocket wheel C2 and consequently the rate of travel of the
endless web B² will be slower than the revolutions of the sprocket wheel C¹ which
will also be slower than the sprocket wheel C, each of the webs B, B' thus
travelling at a higher speed than that of the web immediately below it. The
sprocket wheels E may be driven by any suitable combination of gearing, that
shown being a combination of mitre wheels G, a worm wheel_H, driven by a
worm J, mounted on the worm shaft K, upon which a speed cone L is mounted by
which the time taken for the material to pass through the drying chamber from
the inlet M to the discharge N may be varied. The material to be exposed to the
action of the hot air or other gases passing through the machine is fed on to
surface of the endless web B at the inlet M whence it is carried on the
trays in the direction indicated by the arrow to the point O where by the dropping
of the trays it is deposited on the lower or returning stretch of the same web and
on reaching the point P the trays again drop and deposit the material on the
upper surface of the second web B¹ from which it is deposited on the lower or
returning stretch of same at the point R and thence at the point S to the upper
surface of the third web B2 from which it falls to the lower stretch of same at the
point T and then into the discharge shoot on the point U.
the
upper
The hot air or other gases are admitted to the machine through the air duct W
and pass down through the webs in the direction indicated by the arrows to the
exhaust duct Y to which a suction fan may be attached. X is a receptacle or
hopper for receiving the material to be fed on to the top web at the inlet M.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I claim
is :-
:-
1. In apparatus for drying tea or other substances, in which the material to be
dried is carried through the same upon a series of two or more superimposed webs
and dropped from one web to the other, means for imparting different relative
speeds of travel to the said webs, whereby the upper web moves faster than that
below the same, all substantially as and for the purposes hereinbefore described and
represented in the accompanying drawings.
2. In apparatus for drying tea or other substances, in which the material to be
dried is carried through the same upon a series of two or more superimposed webs
and dropped from one web to the other, means for imparting the different relative
speeds of travel to the said webs, whereby the upper web moves faster than that
below same, in combination with means for introducing the heated or dried air
above the top web, and for drawing this air downwards through the material to be
dried upon the said superimposed webs to one or more exhaust or exit ports there-

page_text: for under the lowest web of the series, all substantially as and for the purposes
hereinbefore described and represented in the accompanying drawings.
3. The general arrangement or combination of parts substantially as herein-
before described and represented in the accompanying drawings constituting an
improved apparatus for drying tea, coffee, cocoa, grain or other substances.
Dated this 4th day of April 1898.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.