Improved Apparatus for Desiccating.
Year: 1896

page_text: Date of Application; 11th Feb., 1896
Complete Specification Left. 1st Apr.. 1896-Accepted, 30th May, 1896
PROVISIONAL SPECIFICATION.
Improved Apparatus for Desiccating.
I, JOHN MELVILL BOUSTEAD Colombo, Ceylon, Merchant do hereby declare
the nature of this invention to be as follows:-
My invention consists in improved apparatus for drying or desiccating tea, and
similar vegetable products; this I accomplish in the following manner:-I mount
in or upon preferably an adjustable frame or frames, a series of plain, porcelain
coated, or other insulated form of iron or other suitable metal wire resistances,
through which a direct or alternating current of electricity is passed in sufficient
quantity to attain the heat necessary for my purpose. The resistances heated by
the current are so controlled by means of a switch or switches as to cut out, off,
limit, or augment, the quantity of current passing. The resistances heated up as
described may be mounted directly under the mesh trays containing the tea or
other vegetable product desiccated, so that the heat rising therefrom passes
upward through said product, or they may be mounted above the product, the hot
air being pulled downwards through it by means of a fan or equivalent means; or
they may be enclosed or shrouded in a metallic jacket or casing of suitable
thickness preferably having a flange around it, and being otherwise so constructed
as that when placed under the mesh or tray containing the leaf or other product
it may catch the fine particles or dust falling therefrom.
The mesh trays in which the products are dried and the adjustable resistances
supplying the heat therefor may be removeably or otherwise mounted up singly,
one above another, or in any other convenient and suitable manner in a self
contained metallic case or jacket, or they may be set in brickwork or the like, a
chimney with or without a fan being added if needful. On the other hand mesh
trays fitted with adjustable resistances may be so constructed as to be applicable
to existing forms of desiccators and like machines.
Dated this 11th day of February 1896.
FRANCIS M. ROGERS,
Agent for Applicant.
Improved Apparatus for Desiccating.
I, JOHN MELVILL BOUSTEAD, Colombo, Ceylon, 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 :-
My invention consists in improved apparatus for drying, or desiccating tea, and
similar vegetable products. This I accomplish in the following manner.
in or upon preferably an adjustable frame or frames, a series of plain, porcelain
coated, or other insulated form of iron or other suitable metal wire resistances,
through which a direct or alternating current of electricity is passed in sufficient
quantity to attain the heat necessary for my purpose. The resistances, heated by
the current, are so controlled by means of a switch or switches as to cut out off,
limit, or augment, the quantity of current passing. The resistances heated up as

page_text: described may be mounted directly under the mesh trays containing the tea or
other vegetable product desiccated, so that the heat rising therefrom passes
upward through said product, or they may be mounted above the product, the hot
air being pulled downwards through it by means of a fan or equivalent means, or
they may be enclosed or shrouded in a metallic jacket or casing of suitable
thickness, preferably having a flange around it, and being otherwise so constructed
as that when placed under the mesh or tray containing the leaf or other product
it may catch the fine particles or dust falling therefrom.
The mesh trays in which the products are dried and the adjustable resistances
supplying the heat therefor may be removeably or otherwise mounted up singly ;
one above another, or in any other convenient and suitable manner, in a self
contained metallic case or jacket, or they may be set in brickwork or the like, a
chimney with or without a fan being added if needful.
On the other hand mesh trays fitted with adjustable resistances, may be so
constructed as to be applicable to existing forms of desiccators and like machines.
I will now proceed to describe my invention more particularly by means of the
accompanying drawing in which :-
Fig. 1, is a plan of one form of electrical heating frame.
Fig. 2, is a side elevation of same.
Fig. 3, is a sectional view of hook to enlarged scale.
Fig. 4, is a cross sertion of hook to enlarged scale.
Fig. 5, is a sectional view shewing mounting of hook in a metallic frame.
Fig. 6, is a modified form of electrical heating frame.
Fig. 7, is a section on line A. B. Fig. 6.
Fig. 8, is a sectional view shewing the application of my invention to single
drying trays or sieves.
Fig. 9, is a longitudinal section of same.
Fig. 10, shews in part section one arrangement of my invention when air is
pulled downward through the material desiccated.
Fig. 11, shews in part side elevation the arrangement I propose to employ when
fitting my
invention to drying machines having a moving web, apron, or endless
band.
Fig. 12, is a plan.
Fig. 13, is an elevation, part of front cover, and side doors being removed,
shewing one form of complete electrical tea drying machine.
Fig. 14, is a side view of exterior.
Fig. 15, is a diagramatic view shewing switching arrangement.
Figs. 1 and 2, shew in plan and side elevation one form of electrical heating
frame I make use of for raising the temperature of the air employed in the
desiccation or drying of tea and other similar vegetable products.
When referred to as a whole these frames are denominated by the letter A.
I prefer to form the sides and ends of the frames 1, of slate, of stout substance,
tongued at the joints 2, and secured by metallic screws or pins 3, screw hooks 4,
preferably having a square screwed sbank pass through holes formed either in the
side or end of the frame as may be most convenient for mounting up. The screw
hooks 4, see also enlarged detail Figs. 3 and 4, are held firmly in position by
screwing up the threaded terminal 5. I prefer to employ steel or hard drawn iron
or other metallic coils of high resistance 8, each coil is preferably formed with an
eye 6, at each end, one end being sprung over the broad shaped screw hook, see
Fig. 4, the other over a similar shaped book 4, forming part of or fitted to the
plate 7, secured by screws, rivets or the like, to the frame as shewn. Any required
number of coils may be mounted in a fraine in the manner shewn. This particular
arrangement permits of the ready removal and remounting of the heating coils
and requires no skilled labour.
Upon attaching conductors 9, to the terminals and causing a current of suitable
strength from a direct or alternate current dynamo machine, secondary battery,
transformer, or equivalent source of electricity to flow through the coils 8,

page_text: mounted up as described, their temperature can he raised until the volume of air
permitted to pass through, over, or under said coils is heated sufficiently for
effecting the particular purpose required. Although I have described the frames
as being built up of slate I do not confine myself to this method of making them;
as they can be formed without joint in porcelain, glass carefully annealed, or
similar refractory insulating substance, or they may be made from cast or wrought
iron the hooks 4, and terminals 5, as well as the plates 7, and bolts passing
through them being insulated by porcelain or slate bushes 71, see Fig. 5. In
Figs. 6, 7, I have shewn another form of resistance heating frame. This consists
of a frame work of slate, glass, porcelain, or other ware 1, the wire 8, on which is
wound over the bars 1", lengthwise as shewn. When formed entirely of slate,
glass, or porcelain the edges of the bars 11 are slightly roughened as by grinding
or filing them so as to give the wire which is wound, as shewn, without touching,
a firm grip or hold. In Fig. 8 I have shewn a drying frame or sieve 10, such as is
employed in drying tea or other vegetable product. This is placed upon the iron
frame 11, set in brickwork or masonry 12, or one or more sieves may be mounted
upon an independent metallic frame or frames if more convenient. The heating
frame A, may as before be made of slate, glass or the like 1, and is by preference
grooved on each side as at 13, so as to be run in upon the tongues or ledges 14,
forming part of or secured as by rivets or otherwise to the casting supporting
the sieve 10. The uppermost heating frame A, is preferably fitted with a remove-
able metallic tray 15, which serves to catch the dust, fine leaf or like substance
passing through the sieve. The heating frame is prevented by a pin stop or the
like 16, see Fig. 9, upon the tongue 14, from completely closing the air way so as
to insure perfect circulation, as see arrows.
In Fig. 10 I have shewn an arrangement of my invention suited to downdraft
drying or desiccatiug apparatus. The heating frame or frames, as the case may
be, are arranged so that the incoming air is pulled or sucked by means of a fun 17,
or chimney replacing it, through the sieves 10, the volume of air being adjusted
by means of a damper 18, or the sir may be forced through the frames A, by
means of a pump fan or like propelling appliance placed on the other side of the
damper.
A tray 15, is placed in the base of the apparatus to catch the small leaf.
In humid climates I may also force or pull the incoming air through or over a
layer of calcium chloride or other like dehydrating material, to prevent as far as
possible the oxidation of the wire heated by the current.
In Figs. 11, 12, I have shewn an arrangement suitable for those forms of drying
or desiccating machines in which the tea or other material is fed on to a moving
web, apron endless band or trays. In such case I prefer to mount the heating
frames A, between the aprons, bands or trays a, or over or under them as may be
most suitable.
In the drawing I have shewn the frames which are constructed in the manner
described mounted upon the frame of the machine b on steady pins c. Any material
passing through the web, apron, or band a, is caught by the trays 15, mounted on
the frames A.
In Figs. 13, 14, I have shewn a complete drying or desiccating machine.
constructed in accordance with my invention. This consists by preference of a
thin sheet iron or steel shell or jacket 19 surmounted by chimney 20, and fitted
preferably with a damper 201, actuated by a counterbalanced lever 18' and rack 21,
the lever 181, being adjustably held in position by a pin 22. The machine may to
prevent radiation be mounted in brick-work or masoury 12 or it may be lagged
with asbestos or other nonconducting substance 23.
The lower part of the apparatus is divided off by a series of cast iron racks 24,
or these may be replaced by angle irons rivetted or secured in any suitable manner
to the skin or frame-work. The heating frames A, consisting preferably of one
or other of the forms described are placed within these racks so that the air
admitted by the dampers 18, passes freely through and around them. The

page_text: conducting wires 9, are preferably passed through short porcelain tubes 711, and
are led out on either side as shewn. Within the jacket 19, is a frame 1911, this
may be made of thin cast iron plates, fitted with guides or runners 26, for the
trays or sieves 10, or it may be made of thin sheet iron or steel the guides or
runners being formed of angle iron or the like, a series of bafflers 27, formed of
sheet metal are in either case so disposed as to cause the air to pass from the
beating frames shewn on the left under and over the trays, as see arrows, or if
arranged as shewn to the right, upwards through them. A tray 15, is mounted as
shewn to catch any small leaf passing through the sieves. It is to be understood
that when in operation the main and side doors 28, 28, are closed and that the
previously dehydrated or ordinary air is admitted and regulated by means of the
dampers 18. The air passing out from the chimney may he conducted to a
withering loft if desired. The operation of this form of my invention is as
follows The current being switched on, the wires mounted in the frames A,
arranged as shewn, are heated up and a current of pure air free from sulphurous
acid, carbonic oxide, or acid fumes, passes over or through the tea leaves or other
material placed in the sieves. The degree of heat can be regulated by admitting
cold air by means of the dampers or by means of the switching device shewn
diagramatically in Fig. 15, in which A, represents a set of frames joined up in
series. The switch lever when in position shewn permits the current flowing from
the dynamo machine 30, or equivalent source of current replacing it to flow through
the entire set; by putting the switch on to the contacts 2, 3, or 4, any, or all may
be cut out.
It will be seen that by means of my improved apparatus I dispense entirely
with the necessity for a furnace heated by coal, wood, or other fuel, and save the
cost of such fuel and attendance. The air is perfectly pure and free from smell
and its temperature can be perfectly adjusted by throwing in or out more or less
of the heating devices or admitting cold air.
In most countries in which tea is found water power is available, and whenever
possible I prefer to employ such for actuating, the dynamo machine producing the
current. It must be understood that the shapes of the heaters and their dis-
position in apparatus for desiccating or drying tea and the like may be varied to
suit special circumstances. For instance:-additional trays placed side by side,
or one under the other, may be embodied in suitably modified apparatus similar to
that shewn in Figs. 13, 14. The exceedingly small size of the heating devices
enable them to be readily fitted to most forms of already existing apparatus
without expensive alterations. The heating frames may be coupled in single or
multiple series, or in parallel circuit as may be most convenient. Although frames
formed of metal such as iron coated with silicate paint, enamel, or other insulating
compound, or the conductors in which are insulated in the way I have described
are convenient from a manufacturing point of view, there is a considerable loss
when in use due to the conduction of the metal.
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 desiccating or drying tea and similar vegetable products the
combination and use of a conductor of high resistance the temperature of which is
raised by the passage of a direct or alternate current of electricity for the purpose
of heating the air passing over, under, or through said product.
2. For the purpose of dehydrating tea and other vegetable products the com-
bination with apparatus for this purpose and use of electrically heated conductors
formed and mounted up in the way and manner shewn, and described herein.
3. The combination in or with au electrical heating frame employed for desiccating
or dehydrating vegetable products, of the removeable tray shaped cover 15,
substantially as shewn in Figs. 8, 9, 11, for effecting the purpose described.
4. In apparatus for drying tea and the like by electrically heated air the com-

page_text: bination of the frame 11 fitted with tongues 14, which engage with the grooves 13,.
formed in the heating devices for effecting the purpose set forth.
5. The combination in or with downdraft apparatus for desiccating or drying
vegetable products the air current in which is heated electrically of the particular
arrangement of the heaters shewn and described.
6. The combination and use in or with tea drying and like apparatus operated
by a fan or equivalent apparatus for propelling or withdrawing air, of electrical
heaters for raising the temperature of the air circulated thereby.
7. For the purpose of drying or desiccating tea and similar vegetable products.
by electrically heated air, the particular form of apparatus described and shewn in
Figs. 13, 14.
8. In apparatus for drying tea and the like by electrically heated air the com-
bination of the sieves 10, the racks 24, for supporting the frames A, arranged as
shewn, the electrical connections to said frames, the leads insulated from the jacket
by the tubes 7, and the dampers 18, all as described and cooperating in the way
and manner and for the purposes set forth.
9. The combination and use with apparatus employed for desiccating or drying.
tea and like vegetable products having an endless web, moving trays, or the like,
of the electrical heating frames formed as shewn and mounted upon steady pins c,.
or otherwise, above, between, or below, said webs or trays.
10. The combination and use in or with apparatus employed for desiccating or
drying tea and similar vegetable products by electrically heated air of the circuit.
controlling devices described and shewn.
Deted this First dor of Annil 1904.
FRANCIS M. ROGERS,
Agent for Applicant.