Improved Means for Obtaining a Forced Draught in Steam-boiler and other Furnaces
Year: 1896

page_text: Date of Application, 27th Feb., 1896
Complete Specification Left, 27th Nov., 1896-Accepted, 23rd Jan., 1307
PROVISIONAL SPECIFICATION.
Improved Means for Obtaining a Forced Draught in Steam-boiler
and other Furnaces.
We, JOSEPH APSEY, Engineer, of 252 South Lambeth Road, and FREDERICK
BARKER HILL, Engineer, of 30 Glengall Road, Old Kent Road, both in the
County of Surrey, do hereby declare the nature of this invention to be as
follows:-
Our invention relates to improved means for obtaining a forced draught in
steam-boiler and other furnaces, and is chiefly designed to ensure that the air shall
be distributed equally or uniformly and at an elevated temperature and under
a suitable pressure beneath the whole area of the grate.
In some of the forms of apparatus hitherto constructed for obtaining a forced
draught, the air has been allowed to impinge at particular points or beneath only a
comparatively small area of the grate, thus causing the combustion to be unequally
accelerated at such points with liability to rapid burning away of the fire-bars and
wasting of the fuel by forming holes in the fire.
Now according to our said invention we provide as hereinafter mentioned for
distributing the air at an elevated temperature and under a suitable pressure
equally or uniformly beneath the whole area of the grate.
For this purpose we close the ash-pit and arrange one or more casings beneath
the grate preferably parallel to the side-walls of the furnace. The said casing or
casings are closed at both ends and provided with perforations preferably arranged
along the sides thereof. In the interior of each casing is provided a tube one end
of which is open to the external atmosphere, or to an air-supply pipe, and has a
steam-jet or injector-nozzle for drawing in the air; whilst the other end of the said
tube is also open and extends to within a short distance of the inner end of the
perforated casing.
By this arrangement the air drawn in by the action of the jet of steam or the
like passes throughout the length of the inner or injector tube, being warmed on its
way, and then returns along the perforated casing, in which it is further heated,
after which it is forced under a suitable pressure from the perforations in the said
casing, and, passing through the grate, comes into contact with the fuel thereon.
By arranging the perforations at the sides of the casing we obviate any risk of
their being choked or clogged by ashes or cinders falling from the grate.
If desired, however, they may be arranged in any other suitable manner.
By our invention we are enabled to provide a very efficient apparatus for the
purposes specified, which entirely obviates auy risk of wasting fuc! or burning the
fire-bars by localization of the draught to one or more points or to a small area of
the grate.
If desired two or more injector-tubes can be arranged within a single perforated
casing.
It is advantageous to provide an opening in the underside of the casing at or
near the end thereof next the plate which closes the ash-pit, so that any ashes that may
be deposited in the said casing will be carried by the air-current to such opening,
and will fall through the same into the ash-pit.
Did she 07th dar of February 1896
D. YOUNG & Co.,
11 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicants.

page_text: Improved Means for Obtaining a Forced Draught in Steam-boiler
and other Furnaces.
We, JOSEPH APSEY, Engineer, of 252, South Lambeth Road, and FREDERICK
BARKER HILL, Engineer, of 30, Glengall Road, Old Kent Road, both in the
County of Surrey, 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 :-
Our invention relates to improved means for obtaining a forced draught in
steam-boiler and other furnaces, and is chiefly designed to ensure that the air shall
be distributed at an elevated temperature and under a suitable pressure equally or
uniformly beneath the whole area of the grate.
In some forms of apparatus heretofore constructed for obtaining a forced
draught, the air has been introduced beneath the grate through tubes extending
inward a short distance from the front of the ash-pit, into which tubes currents of
air are induced by menus of steam-jets, the ash-pit being closed so that all the air
required for supporting combustion must pass through the said tubes. With such
an arrangement, the greater part of the air supplied through the said tubes
impinges upon the fuel near the inner ends of such tubes, the remainder being
distributed beneath other parts of the grate. The consequence is that the
combustion of the fuel near to the inner ends of the tubes is unduly accelerated
with liability to burning away of the fire-bars and wasting of the fuel by the
formation of holes through the fire. In other instances, air-chests having their
upper side perforated have been arranged beneath the grate in an open ash-pit;
but in such an arrangement the air is not efficiently or
the force of the currents of nir entering the said air-chests prevents the rising of
equally distributed because
the air through the perforations near the front of the grate; and this arrangement
bas the further disadvantage that the perforations are liable to be choked by the
ashes falling upon the top of the air-chests. Moreover in both of the forms of
construction above referred to, the temperature of the air is not appreciably
clevated before it comes in contact with the fuel.
Now according to our said invention, we provide as hereinafter described for first
heating the air and then distributing it under a suitable pressure equally or
uniformly beneath the whole area of the grate.
For this purpose, we employ one or more perforated casings suitably arranged
beneath the fire-grate and having one or more tubes arranged within each of them,
and we force the nir under a suitable pressure through such tubes so that it is
discharged from the inner end thereof into a perforated casing or casings, in which
it returns along the space between the tube or tubes and the casing or casings,
being heated by radiation during its return; the heated air passing out through
the perforations of such easing or casings is distributed uniformly beneath tho
grate so that the combustion of the fuel is approximately uniform throughout
the fire.
By this method of supplying the air for promoting combustion, not only do we
keep the fire free from clinker and prevent burning of the fire-bars, but wa
considerably reduce the consumption of fuel, and we are enabled to use slack
or other fuel of an inferior quality, as, owing to the efficient distribution of
the air, there is less liability to blowing of the dust or small coal over the fire-bridge
unconsumed.
In the necompanying drawing we have shown how our said invention may be
conveniently and advantageously carried into practice.

page_text: Figure 1 is a side elevation, partly in longitudinal central section, of one form
of our improved apparatus..
Figure 2 is a transverse section of the same.
Figure 3 is a longitudinal central section showing a slight modification of our
invention.
Figure 4 is a longitudinal central section, and
Figure 5 a front elevation of a steam-boiler having our improvements applied
thereto, and
Figure 6 is a longitudinal central section illustrating another slight modification
of our said invention.
a is the perforated casing; b is the inner tube. These parts are preferably
brazed or otherwise firmly secured to a flanged piece c whereby they may be readily
attached to the front-plate d of the furnace as shown in Figures 4 and 5. The
apparatus shown in Figures 1 and 2 is provided with a jet or injector nozzle e fixed
in any convenient manner in line with the tube b and near the outer end thereof.
Through this nozzle steam or air from a blower, fan or compressor is to be injected.
for the purpose of causing an induced current of air to enter the said tube. In
the modification of our apparatus shown in Figure 3, the pipe b is connected
to a pipe through which air is to be forced by means of a blower, fan or
compressor.
In the arrangement shown in Figures 4 and 5, three of our perforated casings a
with inner tubes band jet or injector-nozzles e, are arranged beneath the fire-grate.
of the boiler. The nozzles e are connected with a common supply-pipe e' provided
with a controlling valve or cock e. Each casing a is closed with the exception of
the perforations a', of which there are preferably two rows, one at either side, as
shown in Figures 1 and 2, and each casing extends along beneath the fire-grate to
or nearly to the inner end thereof. The inner tube extends to within a suitable
distance from the inner end of the casing a.
We sometimes make the bearer-bar for supporting the fire-bars with a
downward extension having holes therein through which are passed the
casings a, so that the said bearer-bars will serve also for supporting the said
casings.
By the arrangement above described, the air drawn in by the action of the jet
of steam or air passes throughout the length of the inner or injector tube b, being
warned on its way, and then returns along the space between such tube and the
perforated casing a, in which it is further heated by radiation, and, the pressure
accumulating in the said casing, the air is forced through the perforations in
the said casing, passes through the grate and comes into contact with the fuel
thereon.
By arranging the perforations at the sides of the casing as shown we ensure
a very effective distribution of the air whilst obviating any risk of the said
perforations being choked or clogged by ashes or cinders falling from the grate.
If desired, however, the said perforations may be arranged in any other suitable
position.
It is advantageous to provide an opening g in the underside of the casing a at or
near the outer end thereof, so that any ashes that may enter the said casing will be
carried by the air-current to such opening, and will fall through the same into the
ash-pit.
In Figure 6 we have shown our improvements applied to a boiler with a
closed ash-pit, a door or flap d' being provided to permit the withdrawal of the
ashes.
Our improvements can be applied to existing boilers without the necessity for
any structural alterations therein, a separate plate or frame being secured, if
necessary, to the front end of the furnace to support the perforated casing or
casings.
By our invention we provide a very efficient apparatus for the purposes specified,

page_text: which entirely obviates any risk of wasting fuel or burning the fire-bars by
localization of the draught to one or more points or to a small area of the grate.
If desired two or more of the aforesaid injector-tubes can be arranged within
ench perforated casing.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
First. The improved method of obtaining a forced draught in steam-boiler and
other furnaces, by the introduction of air under pressure into one or more per-
forated casings extending beneath the fire-grate, through a tube or tubes extending
within such casing or casings nearly to the inner end thereof, substantially as
bereinbefore described.
Second. The combination of a perforated casing extending longitudinally beneath
a fire-grate, a tube within the said casing extending from the outer nearly to the
inner end thereof, and a jet or injector-nozzle at the outer end of the said tube,
substantially as hereinbefore described and for the purposes specified.
Third. The improved apparatus constructed substantially as described with
reference to Figures 1 and 2 or to Figure 3 of the accompanying drawing and
operating as, and for the purposes, above specified.
Fourth. A steam-boiler provided with one or more perforated casings having
inner tubes and means for inducing or forcing air into the inuer tubo or tubes
substantially as described with reference to Figures 4 and 5 or to Figure 6 of the
drawing and for the purposes above specified.
Dated the 25th day of November 1896.
D. Young & Co.,
J. APSEY.
F. B. HILL.
11 & 12 Southampton Buildings, London, W.C..
Agents for the Applicants.