IMPROVEMENTS IN DRYING MACHINES
Year: 1885

page_text: I WILLIAM ALFRED GIBBS of Gilwell Park, Chingford in the county of Essex,
Gentleman do hereby declare the nature of my said invention for "IMPROVEMENTS
IN DRYING MACHINES to be as follows:-
26
My present improvements have reference to the patent tea drying cylinders now
largely used in India and known as "The Gibbs and Barry tea dryer" and also to
similar cylinders extensively adopted in Great Britain and New Zealand for drying,
conditioning and cooling wheat and other products and known as The Gibbs
These cylinders are described in the specification of my former Letters patent
No 1380 dated the 30th March 1876; they are provided with shelves and cross
cells on their interior circumference whereby as the said cylinders rotate the tea
or other product is lifted up and let fall on the fixed air ducts.
wheat dryer."
Although the results obtained by these machines have been sufficiently satisfactory
to create a large and continued demand for them there are defects in the movement
which the present improvements are intended to remove especially when applied
to tea.
The main defect of the present machine is that in order to keep the openings of
the fixed air-duct continuously covered and thus prevent waste of hot air the
cylinder must rotate at least eight revolutions per minute and at this speed, as
the leaf has to fall some distance from the shelves on to the air-duct it is liable to
be broken; so much so that it has hitherto been found advisable to complete the
drying in trays and other stationary machines. To rectify this defect I now
construct the air ducts of such sections as to form a combination of trays and
air-ducts and I cause these trayed air-ducts to revolve very slowly in the same
direction as the cylinder either by separate gear or by attaching them with rods or
stays to the cylinder itself. The beneficial effect of this arrangement is to catch
the tea as it falls off the shelves or cells from the ascending side of the cylinder
and to pour it gently back on to the shelves of the descending side so as to avoid
the breaking action. Another advantage of this form and movement is the larger
quantity of produce held for a longer time under the action of the hot air.
I construct these trayed air-ducts of either fire proof canvas, wire net, perforated
metal or plain plates and they can be constructed of a triangular, square, polygonal
or circular section.

page_text: Any of these sections can have longitudinal slits, openings or mouths running
the whole length to promote the diffusion of air through the cylinder but I find it
preferable to construct them in short lengths and to join them together in such
a manner as to leave air spaces between each length; this is best done by making
the lengths in a series each one of which is a size smaller than the one preceding it.
Thus when the circular section is adopted the air duct presents the appearance of
a large telescope with air spaces between each length and as a matter of convenience
and for reduction in cost of freight and transit they can be so constructed as to
sliut up like a telescope, so that an eighteen or thirty six feet length can be reduced
to about two or three feet. These air ducts require a number of shelves to be
attached to their exterior circumferences so as to form trays in the spaces between
the said shelves.
Whatever section is adopted I either expand the breadth of the shelves in
proportion to the gradual contraction of the air-duct or deepen the shelves and
cross cells on the cylinder in a like proportion.
In order to retain the products still more effectually under the action of the hot
air I sometimes construct, one or more baffle plates or wire guards across the trays
at such distances and intervals as may be found best for the special product which
has to be dried.
These baffle plates prevent the waste of heat that occurs if the air is allowed to
pass too rapidly out of the cylinder and also the waste of the lighter particles of
tea or other product which it carries out with it; they have the further use of
deflecting a portion of the hot air into the shelves or cells of the cylinder and
thereby accelerating the drying process. The hot air to supply these air ducts is
derived from furnaces or hot pipes direct, or waste heat from fires employed for
other purposes, or from steam or hot water coils; either fans or blowers or steam
or air injectors in connection with any of these sources of heat can be used to
deliver in the hot air to the said air-ducts.
G. F. REDFERN,
4, South Street, Finsbury, London,
Agent for the Applicant.
3

page_text: I WILLIAM ALFRED GIBBS, of Gilwell Park, Chingford in the county of Essex
Gentleman 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 present improvements have reference to the patent tea drying cylinders now
largely used in India and known as "The Gibbs and Barry tea dryer" and also to
similar cylinders extensively adopted in Great Britain and New Zealand for drying,
conditioning and cooling wheat and other products and known as "The Gibbs
wheat dryer,"
These cylinders are described in the specification of my former Letters Patent
No 1380 dated the 30th March 1876; they are provided with shelves and cross
cells on their interior circumference whereby as the said cylinders rotate the tea or
other product is lifted up and let fall on the fixed air ducts.-I now construct the
air-ducts of such sections as to form a combination of trays and air-ducts and
I cause these trayed air-ducts to revolve very slowly in the same direction as the
cylinder either by separate gear or by attaching them with rods or stays to the
cylinder itself. The beneficial effect of this arrangement is to catch the tea as it
falls off the shelves or cells from the ascending side of the cylinder and to pour it
gently back on to the shelves on the descending side so as to avoid the breaking
action. Another advantage of this form and movement is the larger quantity of
produce held for a longer time under the action of the hot air.
I construct the air-ducts of either fire proof canvas, wire net, perforated metal or
plain plates and they can be constructed of a triangular square, polygonal or circular
section.
My present improvements are illustrated in the accompanying drawing in which
figure 1, represents a transverse section of a drying cylinder provided with com-
bined trays and air-ducts according to the said improvements the said air-ducts
being shewn circular in cross section; figures 2, 3 and 4, are similar views to
figure 1, but shewing the air ducts of triangular square and polygonal forms
respectively in cross section.-Similar letters in all the figures refer to similar
parts.
a represents the drying cylinder and b, b, the shelves or cells of the same the
said cylinder and shelves being of known construction; the air-ducts I construct as
shewn so as to form a combination of trays c, and air-ducts d, and I cause the
same to revolve slowly in the same direction as the cylinder a, as hereinbefore
described,
Any of the sections described and represented can have longitudinal slits,
openings or mouths running the whole length to promote the diffusion of air
through the cylinder a, but I find it preferable to construct them in short lengths
and to join them together in such a manner as to leave air spaces between each
length; this is best done by making the lengths in a series each one of which is a
size smaller than the one preceding it. Thus when the circular section is adopted
as shewn in figure 1 the air-duct presents the appearance of a large telescope with

page_text: air spaces between each length and as a matter of convenience and for reduction in
cost of freight and transit they can be so constructed as to shut up like a telescope
so that an eighteen or thirty six feet length can be reduced to about two or
three feet.
If made circular in section I provide the air-ducts d, with four or more shelves e
(four being shewn in the drawing) which are attached to their exterior circum-
ferences so as to form the trays c, in the spaces between the shelves e.
If of triangular, square or polygonal section the shelves e, are arranged as shewn
in figures 2, 3, and 4 respectively.
Whatever section is adopted I either expand the breadth of the shelves e, in
proportion to the gradual contraction of the air-duct d, or deepen the shelves b and
cross cells on the cylinder a in a like proportion.
In order to maintain the products still more effectually under the action of the
hot air I sometimes construct one or more baffle plates or wire guards (not shewn
in the drawing) across the trays c, of the air-duct d, at such distances and intervals
.as may be found best for the special product which has to be dried.
These baffle plates prevent the waste of heat that occurs if the air is allowed to
pass too rapidly out of the cylinder a, and also the waste of the lighter particles of
tea or other product which it carries out with it; they have the further use
of deflecting a portion of the hot air into the shelves and cells of the cylinder and
thereby accelerating the drying process. The hot air to supply the air ducts d, is
derived from furnaces or hot pipes direct or waste heat from fires employed for
other purposes, or from steam or hot water coils; either fans or blowers or steam
or air injectors in connection with any of these sources of heat can be used to
deliver in the hot air to the said air-ducts.
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 a drying machine such as is herein referred to the construction of the
improved air-ducts of various sections in which the exterior surfaces of the air-
ducts form, a series of trays over which streams of hot air are caused to pass
substantially as hereinbefore described and illustrated in the various figures of the
accompanying drawing.
2. In a drying machine such as is herein referred to the combination of the
trayed air-ducts with cylinders having shelves or cells the said air-ducts being
rotated either by means of independent gear or by attaching them to the cylinder
itself substantially as hereinbefore described.
3. Constructing the said air-ducts in such a manner that they can be shut up
into a small compass so as to render them compact and portable substantially as
herein before described.
4. The use in combination with the trays of the said air-ducts of baffle plates or
guards whereby the hot air is deflected into the cylinder and waste of air and the
finer particles of the product prevented substantially as herein before described.
Dated the 10th dow of Naziambo 190: