Improvements in or connected with Furnaces for the Production of Hot Air for Drying and other Purposes.
Year: 1894

page_text: Date of Application, 25th May, 1894
Complete Specification Left, 23rd Feb., 1895-Accepted, 6th Apr., 1895
PROVISIONAL SPECIFICATION.
Improvements in or connected with Furnaces for the Production of
Hot Air for Drying and other Purposes.
I, WILLIAM ALFRED GIBBS, of Gilwell Park, Sewardstone, in the County
of Essex, Gentleman, do hereby declare the nature of this invention to be as
follows:-
:-
My invention relates to furnaces for the production of hot air, and has for its
object to provide improved means for obtaining hot air as free from smoke and
fumes as possible.
In applying my improvements to the furnace described in the Complete Speci-
fication of my Application No. 9721 of 1893 I arrange within the chamber into
which the products of combustion are drawn from the furnace, a series of tubes or
the like having their ends placed one within another and having spaces left
between them so that air driven through the said tubes from a fan or blower will
cause the hot air from the said chamber to be drawn into the said tubes and mix:
with the air delivered by the fan. In this application the wire-gauze or the like
at the top of the chamber may be dispensed with, the said top of the chamber
being closed. If desired, wire-gauze may encircle the tubes or the parts thereof
adjacent to the openings.
In order, when using an engine furnace for the production of hot air, to free-
the latter from smoke I arrange adjacent to the smoke box and between the latter
and the fan a fire-chamber or auxiliary furnace for containing incandescent coke
through which the products of combustion from the ordinary furnace are drawn to
ensure perfect combustion. More or less air may be admitted directly into the
said fire-chamber if desired. This fire-chamber or auxiliary furnace is preferably
constructed either of tubes through which water from the boiler may circulate or
of any other desirable boiler form in order that the heat in the said auxiliary
furnace may assist in generating steam in the main boiler.
This auxiliary furnace is made so as to be readily attachable and removable and
is especially applicable to traction and portable engines when used in conjunction
with harvest saving drying machines and with my drying machinery or cylinders.
as now largely used in India and the Colonies for drying tea, coffee, megass, all
kinds of grain and other products.
Dated this outh - 6 M. 1001
5 Improvements in or connected with Furnaces for the Production of
Hot Air for Drying and other Purposes.
I, WILLIAM ALFRED GIBBS, of Gilwell Park, Sewardstone, 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 invention relates to furnaces for the production of hot air, and has for its

page_text: object to provide improved means for obtaining hot air as free from smoke and
fumes as possible.
In applying my improvements to the furnace described in the Complete Speci-
fication of my Application No. 9721 of 1893 I arrange within the chamber into
which the products of combustion are drawn from the furnace, a series of tubes or
the like having their ends placed one within another and having spaces left between
them so that air driven through the said tubes from a fan or blower will cause the
hot air from the said chamber to be drawn into the said tubes and mix with the air
delivered by the fan. In this, application, the wire-gauze or the like at the top of
the chamber may be dispensed with, the said top of the chamber being closed.
If desired, wire-gauze may encircle the tubes or the parts thereof adjacent to the
openings.
In order, when using an engine furnace for the production of hot air, to free the
latter from smoke I arrange adjacent to the smoke box and between the latter and
the fan a fire-chamber or auxiliary furnace for containing incandescent coke
through which the products of combustion from the ordinary furnace are drawn to
ensure perfect combustion. More or less air may be admitted directly into the
said fire-chamber if desired. This fire-chamber, or auxiliary furnace is preferably
constructed either of tubes through which water from the boiler may circulate or
of any other desirable boiler form in order that the heat in the. said auxiliary
furnace, may assist in generating, steam in the main boiler.
This, auxiliary furnace is made so as to be readily attachable and removable and
is especially applicable to traction and, portable engines when used in conjunction
with harvest saving drying machines and with, my drying machinery or cylinders
as now largely used in, India and the Colonies for drying tea, coffee, megass, all
kinds of grain and other products..
One form of hot air producing furnace is shewn in Figures 1 to 4, Figure 1. being
an end elevation of the furnace :
Figure 2. is a transverse, section:
Figure 3 a longitudinal section; and,,
Figure 4, a side elevation partly in section on the line 4-4, Figure 2.,
near..
The furnace shewn in these figures comprises an arched chamber a built of
masonry, sheet iron or other suitable material and having formed through the walls
the bottom a series of openings.b, b. Along the sides of the walls are
formed troughs, c, c, which form the. furnaces proper,, the said troughs. having
advantageously arranged over them, hinged doors d, d which. serve for covering.
the fire when required.
Inside the chamber a I place baffle walls e, e¹ and in connection with the said
walls, I arrange tubular passages ff the adjacent sides of which are perforated,,
the said passages f,f communicating at their ends with openings 9, 9 respectively
in the end walls of the chamber so as to admit currents of fresh air into, the said
passages, which fresh air mingles with the products of .combustion passing through
the openings b, b into the chamber a through the perforations in the walls of the
said passages f, and so causes perfect combustion.
In order to create the necessary draught through the chamber I arrange through
the latter an induction tube composed of a series of tubular sections of different
diameters, the difference being sufficient to leave spaces between the overlapping
parts of the sections through which the products of combustion can pass in the
direction of the arrows, Figure 3. Through this induction tube I drive a current
of air by means of a fan whereby as the air passes through the said, tube it
induces a draught between the sections and so draws off the products of com-
bustion. The air which passes off from this tube is conveyed to a drying cylinder
or chamber by any suitable means..
It is to be understood that with the furnace just described and with the other
forms of furnace hereinafter described. I may use, an, injector for producing a
draught in lieu of a fan.
In some cases where the materials to be dried may be subjected to relatively

page_text: high temperatures I'combine with the furnace a drying cylinder; such an arrange-
ment is shewn in Figures and 6, Figure 5 being a longitudinal section and
Figure 6 a transverse section on the line 6-6, Figure 5. In these figures
į indicates the drying cylinder which may be arranged in any suitable manner
internally and which, as shewn, is mounted at the ends upon rollers i¹, ¿¹ so that it
may be rotated.
In these figures also the furnaces are represented as communi-
cating directly with the chamber a through openings c¹, e so arranged that the
products of combustion passing through the said openings will impinge against the
onter surface of the cylinder i. In the upper part of the chamber is arranged
the sectional induction tube hereinbefore described. With this arrangement it
will be observed that the products of combustion do not come into contact with the
material being dried.
In some cases I dispense with the drying cylinder within the furnace and
substitute therefor a congeries of tubes j, j as shewn in Figures 7 and 8 which are
longitudinal and transverse sections respectively of this arrangement, the said
tubes being open at both ends and at one end communicating with a hood & in
connection with the drying cylinder with which hood the induction tube h also
communicates. As shewn in the said figures the hot air containing the products of
combustion and passing through the induction tube / mixes with the pure air
heated by passing through the congeries of tubes; but, if desired, when the
products of combustion would injure the material being dried, the pure air which
passes through the congeries of tubes may be alone conducted to the drying
cylinder, the air passing through the induction tube escaping or being used for
another purpose.
Figure shews in longitudinal section a furnace having a drying cylinder
arranged within it in the manner shewn in Figures 5 and 6. The said cylinder,
however, is provided with an arrangement of what I terin interrupted shelves, that
is to say, with shelves which, instead of running continuously from end to end of
the cylinder, extend for only short distances, or, in other words, the shelves are
interrupted at certain points, the interruptions in one row of shelves being opposite
to the sections of the adjacent shelves in a manner which will be readily understood
by reference to Figures 9 and 10, Figure 10 being a section on the line 10-10,
Figure 9. In these figures 1, 1 indicate the sections of one set of shelves,
and, the sections of the adjacent line or set of shelves. The object of this
arrangement is to break up the air currents as much as possible and so prevent
them running underneath the shelves without coming into contact with the
material to be dried as is the case when continuous shelves are used.
I prefer to construct my drying cylinders having these interrupted shelves with
a hollow cone frustum at one end, as shewn at m, Figure 9, as I find that such cone
frustum whilst allowing the escape of the steam produced by the drying process
prevents the air currents from blowing light materials out of the cylinder and
thereby causing waste.
1 sometimes extend the induction tube through the cylinder i arranged within
the furnace as herein before described, whereby I not only utilize the heat due to
the direct impingement of the hot gases of combustion upon the exterior of the
said cylinder but also the radiated heat from the induction tube. Figure 11
illustrates this arrangement in longitudinal section where it will be observed that
the induction tube h from the top of the furnace is extended to near the conical
mouth of the cylinder i. It will be obvious that with this arrangement it is
necessary to arrange the fan so that it not only induces a draught through the
induction tube h but also through the cylinder i around the said induction tube in
the direction of the arrow 1 in the said figure. Figure 12 is a transverse section
on the line 12-12, Figure 11.
In order to enable me to utilize the products of combustion escaping from the
furnace of a portable or traction engine for drying purposes, I combine with the
engine an auxiliary furnace and fan, through which auxiliary furnace the products
of combustion from the smoke-box of the engine are drawn so as to consume all

page_text: smoke. In this case, however, provide for closing the chimney opening of the
engine so as to cause all the products to pass into the auxiliary furnace. This
arrangement of an auxiliary furnace in combination with an engine is represented
in Figure 13 which is a sectional elevation. In the said figure n indicates the
auxiliary furnace which, as represented, consists of a basket formed by coils of
tubes o enclosed in a casing p as shewn clearly in Figure 14 which is a horizontal
section on the line 14-14, Figure 13, the said casing being fixed onto the front of
the smoke-box of the engine by any suitable means, the upper and lower ends of
each coil being connected with the boiler so that the water in the latter can
circulate through the said coils. In the casing p at the smoke-box end of the
auxiliary furnace is formed at the upper part an opening p' through which the
products of combustion pass into the auxiliary furnace and at the opposite end of
the auxiliary furnace at the lower part is formed openings p², p³ communicating
with the fan g driven from the fly wheel of the engine. The lower part of the
basket of the auxiliary furnace is filled with an incombustible material serving as
a filter, such for instance as lime stone, the said filter being sufficiently thick to
extend above the level of the openings p². The fuel for the auxiliary furnace is
placed upon this filter. In lighting the auxiliary furnace I use a smokeless fuel,
such as coke, until the filtering material is rendered incandescent; when, however,
this incandescence is effected I may use wood, coal or other smoky fuel, the smoke
being consumed by passing through the incandescent filtering material.
'
The top of the casing p is provided with a lid or cover which serves for the
introduction of the fuel. s is the damper which I fit in the chimney of the engine
in order to prevent the products of combustion escaping therethrough.
When using this apparatus for drying grass and other crops when cut I connect
to the mouth of the fan an inclined air delivery nozzle y' of the form shewn and I
cause the engine to travel slowly, whereby the hot air will be blown onto the crops
lying on the ground.
When using this apparatus for drying tea, coffee and the like I may connect the
fan directly to an air duct t passing through a drying cylinder i as shewn in
Figure 15.
It is to be understood that any suitable construction of furnace may be used
instead of that which I have described.
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. A double trough furnace having a central chamber through which passes a
sectional induction tube having spaces between the overlapping parts of the several
sections and so arranged that when a current of air is forced through the said tube
it will induce a draught through the furnace, substantially as described.
2. In a double trough furnace having a sectional induction tube as described,
perforated passages so arranged that the products of combustion passing from the
furnaces proper into the central chamber of the furnace will pass through the said
perforated passages which at their ends communicate with the atmosphere,
substantially as, and for the purpose described.
3. In a double trough furnace having a central chamber containing a sectional
induction tube, arranging in the space beneath the said induction tube, a rotating
drying cylinder, substantially as described.
4. In a double trough furnace having a central air chamber and a sectional
induction tube, the arrangement beneath the said induction tube of a congeries of
tubes through which pure air is caused to pass in order to be beated, the said pure
air being used alone or in combination with the air containing the products of
combustion passing out of the induction tube, substantially as described.
5. In a double trough furnace having a central chamber containing a rotating
drying cylinder and a sectional induction tube, extending the induction tube
through the centre of the cylinder whereby not only the heat due to the direct

page_text: impingement of the products of combustion upon the exterior of the cylinder is
utilized but also the radiated heat due to the passages of the products of combustion
through the extended induction tube, substantially as described.
6. The combination with a double trough furnace having a sectional induction
tube, of a drying cylinder having broken or interrupted shelves, the said shelves
being so arranged that the spaces or interruptions of one shelf are opposite to the
sections of the adjacent line or set of shelves, substantially as described.
7. In a double trough furnace having a sectional induction tube and a rotating
drying cylinder providing one end of the said cylinder with the frustum of a hollow
cone, substantially as described.
The combination with a portable or traction engine of an auxiliary furnace
mounted upon or arranged in conjunction with the smoke-box of such engine in
such a manner that the products of combustion escaping from the furnace of the
engine are caused to pass through the auxiliary furnace whereby any smoke which
they contain is consumed, substantially as described.
Dated this 23rd day of February 1895.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.