the Production of Hot Air for Drying and other Purposes.
Year: 1888

page_text: the Production of Hot Air for Drying and other Purposes.
I, WILLIAM ALFRED GIBBS, of Gilwell Park, Sewardstone, in the County of Essex,
Esquire, 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:
4
My improvements relate to the construction of a furnace and air-chambers and to
the combination of these with my well known exhaust fans or other suitable exhaust
fans, so as to obtain a practically pure hot air from coal, wood or other. smoke producing
fuel, the said hot air being applicable for drying and other purposes.
My improvements also relate to means for the better distribution of this hot air
through the air-ducts of my patent drying cylinder and to an improved feeding
arrangement for the further utilization of such hot air.
In order to enable my invention to be fully understood I will proceed to describe
how the same may be carried into practice by reference to the accompanying drawings
in which
Figure 1 is a sectional elevation of my improved furnace and air chambers shewn in
conjunction with a fan and a drying cylinder.
Figure 2 is a plan of the furnace and fan shewn in Figure 1.
Figure 3 is a section on the line x, x, Figure 1.
Figure 4 illustrates the application of my improvements to a furnace of ordinary
construction and
Figure 5 is a plan of the same.
Figure 6 is a section on the line y, y Figure 4 looking in the direction of the
arrow.
Figures 7 and 8 are views of the means I employ for effecting the distribution-of
the air.
a is the feed-chamber preferably of conical shape as shown into which the fuel is
fed, this chamber being perforated with a double row of holes b, b; c is the fire box in
which the fuel is burnt; d is a baffle-plate for deflecting the flame and smoke down-
wards; and e is a "splitting"-plate (supported on channel-irons f, Figure 3) serving
to divide the smoke and flame into two thin streams..

page_text: "
y is a bridge and air-box with a perforated back plate / and an air-hole i in each of
the side walls, as shewn in dotted lines in Figure 2.
open to the
jis a hanging-bridge having a perforated front plate k. The bridge is
air at the top and tapers to about an inch slit at the bottom. m, m³, m² represent
flue-boxes to allow of the withdrawal of dust or clinker from time to time.
The floor of the furnace is hollowed out at n under the hanging bridge j so as to
deflect the flame more effectually.
The arrangement, as thus explained, can either be attached to the existing tea-dryers
of Gibbs and Barry or any other ordinary drying machine, or can have my compound
exhaust and blast fan o attached to it as shewn in Figures 1 and 2 or be attached to a
furnace of ordinary construction as shewn in Figures 4, 5 and 6. In either case the
manner of working is'as follows:
-
The fire-box c and half the feed-chamber a are filled with ordinary coke; some
lighted charcoal is then fed on to the top of the coke and the fan o is set in movement.
When the coke is ignited, coal, wood or other fuel is periodically fed into the chamber a
and without further attention a powerful blast of practically pure air is delivered from
the fan into tho drying cylinder. p or other chamber wherein tea or other produce is
placed to be dried.
"
Sometimes in place of the conical feed chamber a I adjust a feeding-box at the back
of the fire-box with a sliding plate actuated by a screw or levers for slowly pushing
forward the fresh fuel into the fire box.
In the construction of my air-purifying arrangement I have found that the following
general rules should be observed to obtain good results:
:
First The area of the inlet at the lower part of the feed-chamber a should be double
the area of the outlet at the fan mouth.
Second The areas of the spaces between the baffle-plates, spliting-plates, and
bridges, through which the flame has to pass on its way to the fan, should be equal at
all points to the area of the fan mouth so as not to retard the flow of air.
Third: The sum of the areas of the inlets of fresh air to the two bridges should be
one fourth more than the area of the fan-mouth. These however should be provided
with sliding plates so as to allow of the area of the inlet being reduced as required.
These fresh air inlets can thus be used to regulate the temperature of the hot blast
issuing from the fan.
.
For example when the areas are equal to that of the fan-mouth a steady temperature
of from 500° to 550° Fahrenheit is obtained; when a higher temperature is required
the fresh air inlets are partially reduced; and when a lower heat is required they are.
opened wider. If however very moderate heats are desired, say from 250° down to
130° these should be obtained by adjusting an injecting cylinder on to the fan-mouth
so as to draw in and deliver the required amount of cold air without lessening the draught
on the furnace.
The relative areas above given are suited to the ordinary velocities of my especial;
fans and those in general use, but if any want of purity is discoverd in the blast as it
issues from the fan mouth a higher velocity inust be given to the fan.
The economy of fuel obtained by this arrangement arises from the two following
causes. Practically the whole. of the gaseous products arising from the combustion
are utilized without the usual loss of from 25 to 50% of heat wasted in producing
chimney draught. This economy has been already proved by the coke-burning
furnace of my present dryers besides which the water contained in the coal, wood or
other fuel is converted into hydrogen and oxygen by passing through the incandescent
mass in the fire-box; and these besides destroying all the noxious products of
combustion give a large accession of heat to the air.
Tobtain an effective distribution of air through the cylinder by 'adjusting a hinged
deflecting plate q in the air duct as shewn in Figures 7 and 8, in such a manner as
to retard the momentum of part. of the air as it rushes in from the fan, and thus to
spread it more evenly. through the holes that underlie the louvres s. This deflecting
plate y can be adjusted to any desired angle by means of a rod t attached to the said:
plate and passing through a stuffing box at the end of the air-duct.

page_text: My improvement in the feeding arrangement consists in applying an
ther conveyor working in a tube or trough formed of perforated metal, and in
djusting such conveyor so that the substance to be dried passes along the said tube
r trough through the whole length of the cylinder before being delivered into the
ame.
In its passage the material is heated by the steam and hot air generated by the
drying process and thus delivered at the feed end of the cylinder in a better condition
for final drying than if (as now) it were delivered in at the feed end quite cold.
I sometimes construct the spiral worm of the conveyor, of tubes instead of rods,
through which tubes steam or hot air is passed to give additional heat to the tea or
other produce as it passes along.
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. The combination of parts forming the improved apparatus for the production of
hot air, substantially as hereinbefore described and illustrated in the accompanying
drawing.
2. The use of the said improved apparatus for the production of hot air, in combina-
tion with exhaust fans or other apparatus for the creation of currents of air, for drying
and other purposes.
3. The described deflecting plate arranged in the air-duct of the drying cylinder
for the purpose stated.
4. The use in combination with my said apparatus for the production of hot air, of
the improved arrangement of mechanism for feeding the material to be operated upon
5 to the drying cylinder.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.
Dated the 21st day of Apri
5534
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.