Improvements in Apparatus for Creating Forced Draught and Forced Combustion, for Injecting Fuel into Furnaces and the like, Applicable to Steam Boiler and other Furnaces.
Year: 1886

page_text: Date of Application, 3rd Dec., 1886.
Specification Accepted, 28th Jan., 1887.
Improvements in Apparatus for Creating Forced Draught and Forced
Combustion, for Injecting Fuel into Furnaces and the like,
Applicable to Steam Boiler and other Furnaces.
I, HENRY WILSON, of the Phoenix Works, Stockton-on-Tees, in the County of
Durham, Engineer 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 :—
The first part of this Invention consists of an arrangement whereby the ash-pit, or
space under the furnace bars, is closed by a door. This door has a wind channel
round its outer edge, opening through a narrow slit or series of holes into the interior
of the ash-pit. This channel is connected to the wind supply pipe by a branch that
forms a swivel upon which the door hinges. In the centre of the door is an opening
which extends to the inner edge of the slit or holes and is conical in section; a cover
or lid fits into this opening controlled by a screw, so that it may be closed entirely or
opened so as to allow the force of the wind passing out of the slit or holes to draw a
greater or less portion of atmospheric air into the ash-pit as may be required.
I also sometimes connect a pipe to this opening and carry it into the flue or uptake,
by which means a portion of the gases escaping from the fire are intercepted on their
way to the chimney and the draught from the wind jets conveys them under the fire
bars and up through the fire.
The foregoing arrangements may, if required, be fixtures, covering a portion only
of the ash-pit.
A row of fine jets may be placed in close proximity to the opening in ash-pit door,
through which jets of steam, water, oil, or any other fluid may be injected into the
fire with the wind. I also sometimes insert-a jet or series of jets into the wind supply
pipe, through which steam, water, oil or other fluid is injected into the wind pipe
direct and carried with the wind into the fires.
A branch from the main wind pipe carries the wind to an opening into the ordinary
firing door, this branch being utilised for injecting wind over the upper surface of the
fire and thereby preventing the creation of smoke by driving the gases arising from
green fuel down through the fire. It is also utilised for injecting small coal or other
fuel into the furnace, and this forms the second part of this Invention,

page_text: The fuel is fed into a hopper in any convenient way; the hopper may be furnished
with breakers to reduce the fuel to an uniform size; at the bottom of the hopper is
fixed a case containing a revolving drum divided into three or more chambers. The
fuel drops into these chambers and being carried round is discharged across the
course of the wind, which blows it over the surface of the fire, and the wind which
drives the fuel into the fire also at the same time prevents smoke by driving the gases
down through the fire as before described.
As it may in some cases be beneficial to heat the wind to a high temperature,
I sometimes drive it through a heating apparatus, constructed by preference in the
following manner. A case of iron or copper containing a fire is surrounded by an
outer case, both cases being by preference corrugated between the inner and outer
cases is an annular space into which the wind is driven, and the wind passing over the
corrugations is heated up to the required temperature. I also sometimes use steam
instead of fire for heating the wind, the heater being constructed in the manner
described as for fire, but made steam tight in order to stand the required pressure.
I sometimes heat the wind by making the boiler front, or portion which covers the
furnace space, double; by which means a space or chamber is formed, into which the
air is discharged and spreading over the interior surface is heated up. An opening at
one end gives egress for the heated air this opening is covered by a branch leading
into the interior of the firing door, which is also double, having a row of jets to direct
the wind over the fire. While the firing door is closed the wind communication
is intact and when the door is opened the catch that fastens it. communicates by means
of levers with a valve that stops the passage of the wind so long as the firing door is
open. I use the same arrangement for the door that covers the ash-pit, and when this
arrangement is made, the swivels for admitting the wind at the hinged ends of the
doors are dispensed with.
For obtaining the necessary force of wind I use, by preference, the Air Pump
described in my Specification No. 1120880, but I do not confine myself to this or any
other form of forced blast.
The following is a description of the four Drawings which accompany this
Specification.
Drawing No. 1Figures 1 and 2 show part of front and side elevation of a marine
boiler. The wind is introduced by the Pipe H through the Branches G, G, on the
firing and ash-pit doors C. F and passes into the furnace K through the jets D;
and under the grate bars through the jets into the ash-pit I.
Drawing No. 3:-Figures 1 and 2 show furnace front and side elevation suitable
for Lancashire or Marine boiler. The wind enters at A into the hollow space B
between the outer and inner shell, and passes into the hollow fire door by the
branch at side. The wind emerges through the jets D and is injected against the
baffle plate fixed on inner side of door and thence over the fire. A branch E connects
the wind chamber with the ash-pit door F which is hollow round the rim and covered
with a plate having a series of taper holes or jets, set at a suitable angle, through
which the wind is driven under pressure into the space under the grate bars. The
centre of this Ash-pit door is open and controlled by a screw valve as shewn in
Drawing No. 4. P; the use of this being to regulate the supply of air drawn in
by the jets.
Drawing No. 2 Figures 1 and 2 shew the arrangement for drawing unconsumed
smoke and gases from the uptake. The cone L covers the opening round which the
jets are placed. The continuation of the pipe at L' is connected with the uptake. This
arrangement is also utilized for ventilating purposes, the pipe L' in such case being
continued to the required points.
The branch Q is for the injection of any gas or fluid that may be required to assist
combustion or for any other purposes. This branch may be added to any of the
arrangements of this Invention.
Drawing No. 4:-Figures 1 and 2 shew the arrangement for injecting coal or other
fuel into the furnace. The fuel is fed into the Hopper M, which when required is
fitted with ordinary fluted rollers or breakers to reduce the fuel to an uniform size :

page_text: the fuel drops into the divisions of the drum N and is carried round to the point O,
when it drops across the passage of the wind, which injects it into the furnace K.
When this arrangement is adopted the wind for feeding the furnace may be supplied
as shewn by the pipe at A.
Figure 3 shews section of wind heating media when a higher heat is required than
is obtainable from the space in the furnace front, the wind being forced over the
corrugations in the direction shewn by the arrows, the fire or other heating agent
being inside the corrugated case.
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 :-
1st. The closing of the ash-pit and furnace front with doors having wind jets,
as described and shewn in drawings 1 and 3.
2nd. The utilization of the draught caused by the emission of wind from the jets,
for the purpose of collecting partially consumed gases escaping from the fire, as
described and shewn in drawing No. 2.
3rd. Increasing the volume of air supplied under the fire and by this means
ensuring more perfect combustion of fuel and consequent decrease in smoke and
rendering high chimneys unnecessary for draught creation.
4th. The peculiar arrangement of hollow furnace fronts, as described and shewn in
drawing No. 3.
5th. The injection of fuel into the fire by means of wind under pressure, as
described and shewn in drawing No. 4., Figures 1 and 2.
6th. The injection of oils, water, gas, steam or other fluids into the wind passages or
chambers for the purposes of condensation and disintegration prior to injecting either
over or under the fire, as described and shewn in drawings Nos. 1 & 2.
7th. The peculiar form of apparatus for heating air, as described and shewn in
drawing No. 4, figure 3.