Combined Boiler and Furnace.
Year: 1895

page_text: Date of Application, 30th July, 1895-Accepted, 14th Mar., 1896
Combined Boiler and
Furnace.
I, EDWIN POWELL, Manufacturer, residing at No. 13 Alpha Terrace, in the
City of Pittsburgh, County of Allegheny, State of Pennsylvania, and United
States of America, 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 more particularly to furnaces or fire places for steam and
hot water boilers of different descriptions, but is applicable, without variation of
principle or essential features, to boiler furnaces employed in other classes of
service where the utilization of fuel under the conditions of uniform, effective, and
economical combustion is desired. The object of my invention is to provide a
furnace of comparatively simple and inexpensive construction and readily
applicable, within small compass, for such service as may be required, in the
operation of which the combustion of the fuel, particularly when bituminous and
of low grade, may be effected with thoroughness and economy, and without the
inconvenience and waste resultant upon the evolution of smoke.
The improvement claimed is hereinafter fully set forth.
In the accompanying drawings: Figure 1 is a vertical, central section through
a steam boiler setting, illustrating an application of my invention, the section being
taken at the liner, x, of Fig. 2; Fig. 2, a horizontal section through the same,
at the line y, y, of Fig. 1; Fig. 3, a vertical, transverse section, at the line 2, 2,
of Fig. 1; Fig. 4, a front view, in elevation, and, Fig. 5, a side view, in
elevation.
My invention is, in this instance, exemplified as applied in connection with a
vertical water tube boiler, which is designed for the heating of a building by low
pressure steam, and is composed of an upper drun or cylinder 1, a corresponding
lower drum 2, and a series of vertical water tubes 3, connecting said drums. The
lower drum, the water tubes, and the lower portion of the upper drun, are enclosed
within a setting of brickwork 4, which forms the walls of a combustion chamber 5,
surrounding the tubes aud closed at its top and bottom by the drums 1 and 2,
respectively. The combustion chamber 5 is transversely divided by a central
partition 6, of firebrick or tile, which extends upwardly from its bottom for about
three-fourths of its height, and openings 7, 8, are formed in its rear wall, from
which openings, pipes 9, 10, controlled by valves or dampers 11, 12, lead to a
discharge flue or stack 13. Passages 14, in the walls of the combustion chamber
(indicated in dotted lines in Figs 2 and 3), controlled by doors 15, enable access
to be had to the tubes for cleaning purposes. The boiler is provided with a
valved steam delivery pipe 16, leading out of its upper drum, and with the
usual accessories, as a water feed pipe, safety valve, gauge cocks, pressure
gauge, &c.
The boiler above described is of a known type, and does not, in and of itself,
form any part of any invention, which, as before stated, may be applied in connection
vith boilers of other descriptions.
In the application of my invention which is herein described and shown,
provide, at the front of the boiler setting 4, an extension 17 thereof, enclosing a
ertical chamber 18, which is closed at top by a fuel supply door 19, and at bottom
y a firebed 20. The chamber 18, is preferably made of such capacity that its

page_text: upper portion serves as a fuel magazine or receptacle, and the portion adjacent to
the lower end, as a fire chamber. An airtight ashpit 21 is located immediately
below the firebed, and a pan 22, to which water is supplied by a pipe 23, is set on
the bottom of the ash pit. The firebed 20 is preferably in the form of a grate, as
shown, in order to allow ashes and clinkers to drop into the ashpit, as well as to
permit the vapor generated by the heat of the ignited fuel on the firebed, to pass
thereinto and by its decomposition to promote the combustion thereof. An
imperforate plate may, however, be substituted for the giate bars if desired.
While a construction, as herein shown and described, in which the fuel magazine
is integral with and forms a continuation of the upper portion of the fire chamber,
is deemed by me to be preferable in practice by reason of structural economy, it
will be obvious that such is not an essential of my invention, as the fuel magazine
might be made separate from the fire chamber and connected therewith by a
suitable supply chute, or it might, if desired, be dispensed with and fuel fed
to the fire chamber from time to time as required from any other receptacle,
either stationary or portable. In either case, the essential features of con-
struction and mode of operation which characterize my invention would be
complied with, in the same manner and to the saine extent, as in the specific
construction set forth.
The chamber 18 is separated from the combustion chamber 5, by the front wall
of the brick setting, and by a bridge wall 24, which extends across and closes an
opening in said wall for such distance as to form the upper boundary of an exit throat
or passage 25, located at and adjacent to the level of the firebed 20, through which
throat the gaseous products of combustion of the fuel on the firebed pass into the
combustion chamber. The face of the bridge wall 24 adjacent to the chamber 18,
is preferably inclined downwardly in the direction of the combustion chamber, as
shown in Fig. 1, and it is recessed or shouldered at the front portion of its top, to
provide a clear space above the upper end of a gas conduit, consisting, in this
instance, of a series of tubes 26, which extends from its upper to its lower sides
near its top. An air supply passage 27, closed by a door 28, is formed in the front
wall of the setting 17, which encloses the chamber 18, adjacent to the level of the
top of the gas conduits, said wall being, otherwise, closed throughout.
In the instance shown, and, preferably, in other applications of my improvement.
in connection with a boiler, the bridge wall 24 is constructed in the form of a
hollow casting or water back, the gas conduits 26 being made of tubes secured at
each end therein, for which a single channel extending for the major portion of the
length of the bridge wall may be substituted, if desired. A continuous natural
circulation of water into and through the water back is provided for by circulating
pipes 27, 27, one of which, 27, leads from the lower drum 2 of the boiler into the
lower portion of the water back, and the other, 27, from the top of the water back
to the upper drum 1, of the boiler.
In order to enable the exit throat 25 to be readily cleared of clinkers or other
accumulation of solid matter tending to obstruct the free passage of the gaseous
products of combustion to the combustion chamber, a cleaning passage 29 (indicated
in dotted lines in Fig. 2), is formed in the setting 4, at and above the lower level
of the throat 25, said passage being of sufficient width and height to afford ready
access, by a poker or slice bar, to all parts of the throat 25, and being closed at its
outer end by a door 30. An opening or series of openings, 31, closed by a door or
doors, 32, may also be provided at the front of the firebed to facilitate the cleaning
of the fire from time to time, as may be found necessary, and access to the ashpit 21
is afforded through an opening in the front wall thereof, which is closed by tight
fitting doors 33.
In the operation of a furnace in accordance with my invention, the fire chamber
and fuel magazine 18, is supplied with fuel, preferably to a level near or somewhat
below that of the top of the bridge wall, the fuel is ignited, and a proper quantity
of air admitted through the an supply passage 27. The major portion of the hot
gases evolved by the combustion of the fuel pass out through the throat 25, into

page_text: the combustion chamber 5. The heat of the fire being applied directly to the
water back bridge wall 24, highly heats the water therein, generating steam and
inducing a strong natural circulation through the water back, circulating tubes 27ª
and 27, and the drums and water tubes of the boiler. The hot gases passing into
the combustion chamber 5, circulate around the water tubes 3, and impart the
greater part of their heat to the water circulating through said tubes before
escaping into the discharge flue 13. When the fire i started, the damper 12 of
the lower discharge pipe 10 is closed, and the damper 11, of the upper pipe 9,
opened, in order to promote the draught. After the fuel has become thoroughly
ignited, the upper damper is closed, and the lower damper opened, and the hot
gases then circulate upwardly around the tubes on the front side of the central
partition 6, and downwardly around those on the rear side thereof, the heat of the
gases being thus more fully utilized than when they are allowed to escape through
the upper discharge pipe.
In the ordinary constructions in which a downward draught is maintained through
fuel supplied to a firebed from a magazine, no provision has been made which is
effective in practice, so far as my knowledge and information extend, for the
combustion and utilization of such of the gases evolved from the fuel as pass
upwardly through the same, and in some cases, inconvenience is experienced by
reason of the escape of such gases, or their explosion from time to time within the
magazine. Under my improved construction, the evolved gases which pass
upwardly through the fuel are met by a current of air entering the chamber 18
through the air supply passage 27, and, uniting with the air, are drawn downward
through the gas conduits 26, and discharged at the lower ends thereof, adjacent to
the exit throat 25. The heat at this point being very high, the thorough com-
bustion of the gases passing out of the conduits 26 is effected, thereby effecting_a
corresponding economy of fuel, and the prevention of smoke even when low grade
bituminous fuel is employed.
I am aware that down draught furnaces of various constructions, in which fuel
is supplied from a magazine to a firebed, and the gaseous products of combustion
discharged through an opening below a bridge wall, were known in the art prior
to my invention, and such construction I do not, therefore, broadly claim. I am
not, however, aware of any instance in which the admission of air is effected
through a single passage in an otherwise closed front so located as to cause the
air to combine with and carry the gases which rise through the fuel into a conduit
or conduits by which they are delivered at a point where their combustion is
effected by the direct heat of incandescent fuel, such a construction being the
essential and characteristic feature of my invention.
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, substantially as set forth, of a boiler, a combustion chamber
located in position to impart heat thereto, a fire chamber, a lower firebed, a water
back bridge wall interposed between the fire chamber and the combustion chamber
and located above an exit throat or passage adjacent to the firebed, circulating
tubes connecting the water back bridge wall with the upper and lower portions of
the boiler, a tubular gas conduit passing through the water back bridge wall, its
lower end being located adjacent to the exit throat and its upper end being open
to the fire chamber near the top of the water back bridge wall, and an air
supply passage leading into the fire chamber adjacent to the upper end of the
gas conduit.
2. The combination, substantially as set forth, of a boiler, a combustion chamber
in a setting enclosing the heating surfaces of said boiler, a fire chamber in a lateral
extension of said setting, a lower firebed in said fire chamber, a water back bridge
wall abutting on its upper face against the setting wall which separates the fire
chamber from the combustion chamber, and forming the upper boundary of an

page_text: exit throat or passage adjacent to the firebed, circulating tubes connecting the
water back bridge wall with the upper and lower portions of the boiler, a series of
tubular gas conduits passing through the water back bridge wall, their lower
ends being located adjacent to the exit throat and their upper ends being
open to the fire chamber near the top of the water back bridge wall, and an air
supply passage leading into the fire chamber adjacent to the upper ends of the
gas conduits.
3. The combination, substantially as set forth, of a boiler composed of an upper
and a lower drum and a series of connecting water tubes, a combustion chamber in
a setting enclosing the heating surfaces of said boiler, a central partition extending
upwardly in the combustion chamber from the lower drum of the boiler to a level
below the upper drum thereof, valve controlled exit flue passages in the upper and
lower portions of the combustion chamber, a lateral fire chamber, a lower firebed
therein, a water back bridge wall interposed between the fire chamber and the
combustion chamber above an exit throat or passage adjacent to the firebed,
circulating tubes connecting the water back bridge wall with the upper and lower
drums of the boiler, a tubular gas conduit passing through the water back bridge
wall and open at its ends to the exit throat and to the fire chamber respectively,
and an air supply passage leading into the fire chamber adjacent to the upper end
of the gas conduit.
4. A water back bridge wall for boiler furnaces having a plane surface on its
top for a portion of its width, adapted to make a joint with the wall of a boiler
setting, and recessed or shouldered below said plane surface for the remainder of
its width, connections for circulating pipes on the plane surface of its top and on
its bottom, and one or more tubular gas conduits extending from the shouldered
portion of its top to its bottom, substantially as set forth.
Dated.
D
Witnesses
1
J. SNOWDEN BELL.
F. E. GAITHER.
EDWIN POWELL.