Improvements in Apparatus for Supplying Jets of Steam and Air to the Furnaces of Steam Boilers.
Year: 1892

page_text: Date of Application, 4th Oct., 1892
Complete Specification Left, 28th Feb., 1893-Accepted, 29th Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Supplying Jets of Steam and Air to
the Furnaces of Steam Boilers.
I, WILLIAM BRACEWELL, of Brinscall, near Chorley, in the County of
Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows, that is to say :-
The object of my invention is the construction and application of a steam jet
apparatus, for use in the furnaces of steam boilers; the same being worked in
combination with a prescribed volume of atmospheric air, so as to greatly increase
the combustion of coal.
The jet apparatus being by preference placed in an inclined position on the top
and bottom of the furnace bars, thereby causing a combined current of steam and
air to intermix with the incandescent fuel, this inrush of superheated steam and
hot air under pressure having so great an impetus, creates a quicker draught
within the furnace, and also increases the passage of air, through the spaces betwixt
the furnace bars, by this means a greater temperature is arrived at within the
furnace, causing more steam to be generated, and a greater combustion of the
incandescent carbon, when liberated from the burning fuel.
By the judicious working of my arrangement the percentage of oxygen necessary
to create complete combustion can be regulated to meet the various qualities
of fuel. The proportion of atmospheric air admitted to the steam jets being under
regulation.
To carry out my invention I construct a diminishing jet actuated by steam,
having an annular chamber surrounding the same, provided with four or any
number of holes in its outer periphery for the admission of air.
The jet being placed concentric with the chamber, creates an equal percentage
of air to be admitted on all its sides.
The exit end of the annular chamber is formed with a diminishing nozzle, but of
a much greater area than the steam jet so that the intermixture of steam and air,
can enter the furnace in a larger volume and thereby create a better and more
diffused current for action upon the fuel and gases within the furnace. For
covering the outer holes in the annular chamber, I provide a circular plate of
metal having openings equal in area to the chamber beneath them, provision being
made so that a sliding motion can be imparted to the plate, so as to regulate the
admission of air within the chamber.
The closing of the openings in the annular chamber tends to diminish the noise,
usually made upon the working of steam jets.
To better carry out my invention I place the jet within the furnace, in close
proximity to the furnace door, having a baffle plate attached to the door, with
openings for the admission and direction of the current of atmospheric air to
the jet.
In cases where this is not of practical application, I place my arrangement, on
the outside and above the furnace door, but in all cases the current is made to
impinge upon the burning fuel in an inclined direction.
In combination with the jet, above and within the furnace, I also place another
jet actuated by steam or other propelling fluid under pressure, for the admission of
steam and air under the furnace bars, the jet being placed within a hollow chamber
formed beneath the dead plate of the furnace, from which chamber, I carry longi-
tudinal pipes the full length of the furnace for the conveyance of steam and air, the
pipes having openings along the sides thereof, for the outlet of superheated steam
and air along the air spaces of the fire-bars.

page_text: The longitudinal pipes are bent up and made to terminate within a hollow bridge
so that any excess of the current can be delivered in contact with the gases and
incandescent carbon, passing over the back bridge of the furnace.
Dated this 4th day of October 1892.
WILLIAM BRACEWELL.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Supplying Jets of Steam and Air to
the Furnaces of Steam Boilers.
I, WILLIAM BRACEWELL of Brinscall near Chorley, in the County of Lancaster,
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 object of this invention is to provide apparatus whereby a jet of steam in
conjunction with a prescribed volume of atmospheric air may be supplied to the
furnaces of steam boilers in order to promote the complete combustion of the fuel
and prevent the formation of dense or black smoke.
It consists essentially of a jet or sprayer constructed with an inner nozzle
surrounded with an annular air chamber provided with inlet holes and delivering
into a diminishing nozzle of greater area, at the exit end in the form of a truncated
cone and in the combination therewith of air tubes or chambers whereby a mixture
of air and steam is admitted to the furnace at any desired point either at the front
or back or under the furnace and a baffle bridge to deflect the products of
combustion and heated gases and cause a complete intermingling of them with the
steam and air admitted to promote the combustion.
The invention will be fully described with reference to the annexed drawings in
which parts of a steam boiler, furnace and flue are shown sufficient to illustrate it.
Fig. 1. Longitudinal sectional elevation through the furnace.
Fig. 2. Transverse sectional elevation.
Fig. 3. Longitudinal elevation of exit nozzle (enlarged scale).
Fig. 4. Enlarged sectional elevation of steam nozzle and air admission chamber.
Fig. 5. Ditto of exit nozzle.
Fig. 6. Enlarged sectional plan of exit nozzle.
Fig. 7. Longitudinal sectional elevation of a modified form of the appliance.
Fig. 8. Longitudinal sectional elevation of another modification.
Fig. 9. Transverse sectional elevation of same.
The boiler A the furnace B and the flue C to which the invention is applied are
of any ordinary form or construction.
The jet or injector is formed with a nozzle D placed in the centre of an annular
chamber E provided with four or more inlet openings or apertures e in its periphery.
The periphery is surrounded with a sliding ring or shutter F with corresponding
openings which can be moved to open or close wholly or in part the inlet
apertures e. To the bottom of the chamber E is attached by a pipe e¹ of other
connection an inclined exit or discharge nozzle G in the form of a truncated cone
expanding outwards to distribute the mixed steam and air over the top of the fire,
and branches g g on either side to convey the current of air and steam to any
desired point at the sides bottom or back of the furnace.
Referring to Figs. 1-2 and 3 the jet or injector constructed as shown in Fig. 4
is connected by the tube el fitted with suitable valve ell with the steam space of
the boiler and the discharge nozzle or sprayer G (see Figs. 3. 5-6) is placed
inside the furnace over the furnace door b. The branch pipes g g¹ are carried
down on either side of the door frame and pass through the dead plate H to
perforated tubes I and J placed on either side of the fire box and in close proximity
to the under side of the fire bars K. The tubes I and J are perforated throughout
the whole of their length and from the perforations therein the mixed current of
"

page_text: steam and air impinges upon the under side of the fire the superheated mixture
passing between the bars through the fire. The ends of the tubes I and J pass
through the back bridge L into the combustion chamber M behind it formed by
the baffle bridge or plate N fixed in the flue. The ends of the tubes are protected
from the fire by being enclosed in the brickwork the heat of which also tends
to increase the temperature of the air and steam therein which are delivered at a
high temperature into the combustion chamber M. The baffle bridge or plate N
is formed with a central opening n or two openings towards the sides opposite to
the ends of the tubes. I at present prefer to employ two such openings n in the
baffle plate N in the form of clay pipes built into the baffle bridge and placed
concentric with the ends of the tubes. The unconsumed particles of carbon and the
heated gases passing from the furnace come into contact with the heated air
issuing from the ends of pipes I and J and an almost complete combustion ensues
preventing the passing away of black or dense smoke.
By this arrangement of apparatus a regulated current of mixed air and steam is
discharged over the whole surface of the fire from the discharge nozzle G a further
current is discharged from the perforations in the pipes I and J beneath the fire
which enters between the bars and a current issues from the ends of the tubes into
the combustion chamber M the impetus of which passing-through the concentric
openings n in the baffle bridge N establish an induced or forced draught within the
fire box and complete or almost complete combustion and absence of smoke is the
result.
Referring to Fig. 7 the branch pipes g g' from the discharge nozzle G pass
along the sides of the furnace to the combustion chamber M formed at the back
of the bridge. The pipes are perforated and a current of mixed steam and air
issues therefrom throughout the length of the furnace and a second jet is placed
below the fire door opening into a hollow dead plate to which is connected the
perforated pipes I and J which deliver the mixed steam and air to the under side
of the fire. The pipes may also enter a hollow plate underneath the bridge L
where the mixed air and gas are further heated before being discharged into the
combustion chamber M. This modification may be adopted where an excess of
current or draught is required.
Referring to Figs. 8 and 9 where the space between the door frame and the
crown of the furnace will not allow sufficient for the arrangement of the discharge
nozzle G and branch pipes g g¹ as shown in Fig. 1. I construct a hollow or tubular
door frame and dead plate G₁ so that the jet from the front of the boiler can
charge the cavity formed thereby inside the furnace. The perforated tubes I and J
are connected to the hollow dead plate and pass along beneath the fire bars K as
before to the combustion chamber M. A hollow back bridge or hollow enclosed
chamber below the bridge L may be adopted into which the pipes enter. By
this means connection is made between the cavity within the dead plate or door
frame G' and the cavity in the bridge L the whole being charged with steam and
air from the force of the jet provided at the exterior of the boiler. The action is
precisely the same as that already described with reference to Fig. 1.
If desired the hollow dead plate and back bridge may be used to act as receivers
the combined steam and air being made to pass through one or more tubular fire
bars placed to connect them.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. An apparatus for supplying a jet of steam and air to the furnaces of steam
boilers coustructed with a steam nozzle surrounded by an annular air chamber
provided with inlet apertures opened and closed by a sliding shutter and a discharge
nozzle of truncated cone shape substantially as and for the purpose described.
2. Apparatus for supplying a jet of steam or air to the furnaces of steam boilers
consisting of a steam jet for inducing a current of mixed air and steam, a truncated

page_text: cone shaped sprayer or discharge nozzle for distributing the current over the
surface of the fire, branch pipes and perforated tubes for conveying the supply of
air and steam beneath the fire and into the combustion chamber behind the bridge
substantially as described.
3. The combination with the apparatus herein described for supplying a jet of
steam and air to steam boiler furnaces of a baffle bridge or plate provided with
one or more openings placed in the flue tube to form a combustion chamber through
the openings in which the current is propelled by the air and steam forced through
the tubes substantially as described.
4. Apparatus for supplying mixed gas and air to steam boiler furnaces in
regulated quantities having the several parts constructed and arranged in combina-
tion substantially as described and shown with reference to either of the Figs 1-7
or 8 of the drawings.
Dated this 27th day of February 1893.
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.