Improvements in Boiler Furnaces.
Year: 1894

page_text: Date of Application, 14th Aug.. '891-Accepted, 19th Jan., 1895
Improvements in Boiler Furnaces.
We, DOUGAL JAMES MCKENZIE and WILLIAM MARTIN, Manufacturers,
both of 347 West Monroe Street, Chicago, Cook County, Illinois, United States
of America, do hereby declare the nature of our 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 particularly to the furnaces of boilers, and has for its
object the providing of a simple, economical and efficient boiler furnace
particularly adapted to the complete combustion of fuel, the preventing of the
formation of smoke and the attainment of the highest degree of economy in the
consumption of fuel; and the invention consists in the features and details of
construction hereinafter described and claimed.
In the drawings, Figure 1 is a vertical section of my improved boiler and
furnace, Fig. 2 a transverse vertical section on line 2 Fig. 1 looking in the
direction of the arrow; Fig. 3 a horizontal plan section of a portion of the
furnace, taken on line 3 of Fig. 1 looking in the direction of the arrow and Fig. 4
is a longitudinal section showing the application of our invention to a safety
tubular boiler.
In illustrating our improved furnace, we have shown it in connection with but
one type of boiler-namely, an external fired tubular boiler-but we do not desire
to be limited to this particular class of boiler, as the invention is capable, with
slight mechanical changes, of being used in connection with any or all of the
different classes of boilers now known or in use.
In constructing our improved boiler furnace, we use a boiler, A, preferably of
the return flue type, and provide it with the usual up-take, a, which leads to the
smoke stack to carry off the products of combustion. The boiler may be
supported in any of the usual ways, by means of lugs, a', resting on the side
walls,, A, and by the front walls, A, so as to leave an opening between the
bottom of the boiler and the ground.
Located in this opening-between the boiler and the ground, preferably about
midway the length of the boiler is a bridge wall, B, which may be formed of
ordinary fire brick or fire clay in the following manner: The lower portion, as at B,
is made of vertical pieces of fire clay or fire brick, which rest upon the filling
of earth or fire clay, b, to form vertical spaces or openings, B', as shown in Fig. 2
of the drawings. We interpose between these vertical fire bricks and the boiler
proper a structure composed of a layer of fire bricks, B2, having cylindrical
perforations or openings, 62, which extend clear through the bridge wall. These
cylindrical and vertical openings may, if desired, be connected with each other and
with the vertical openings, so that heated air and gases may freely circulate
through the same, as hereinafter explained.
The fire chamber or fuel box, C, is formed in the following manner: We
surround the interior of the fire box-preferably the rear and two sides-with fire
bricks, C', formed in the manner shown in cross section in Fig. 1, to constitute
what we term a fuel bridge wall, and which rest upon a foundation or wall, C³,
preferably made of fire brick or any desired refractory material. The usual
grate bars, D, rest upon a lug, d, secured to the front walls of the furnace
and legs, D', from which an inclined portion of the grate, d', extends up to be
upported on lugs, d, at the rear wall, upon which the coked or partially burned
D

page_text: fuel may be deposited, as hereinafter described. This grate forms, as will be seen,
the lower portion of the fire box or fuel chamber; while between it and the
bottom of the furnace is the usual ash-pit, E, provided with the usual door, e,
through which the ashes may be withdrawn or air enter, as desired.
The fire box is provided with a door, F, pivoted to a bar, f, such bar
being provided with a segmental gear wheel, F', and adapted to be engaged
and actuated by a ratchet lever, f, the arrangement and construction of such
parts being such as to allow the door to be opened and held in any desired
position for the admission of any quantity of air that may be required. This
door and its operating parts will be made in the usual manner of sheet metal
or steel, either as shown in the drawings or with an air space between its
different parts to more thoroughly protect it from the intense heat of the
'fire box.
To more thoroughly ensure the combustion and economy of the fuel, I
provide the wall at the rear of the fire box with an air chamber, G, having
communication with the outside air by means of the pipe, g, which extends
through the combustion chamber, H, and provided at its rear end with caps, g',
which regulate the admission of the required amount of air. The air chamber, G,
in the first bridge wall, C2, communicates with a cylindrical air chamber, G',
in the fuel bridge wall, which immediately surrounds the fire box by means
of perforations, 92, and with the fuel chamber by means of the perforations, y³,
which enter such chamber, preferably at a point a little above the point of
combustion.
The side bricks,-
-as at C³-are a continuation of the fuel bridge wall and are
also provided with cylindrical chambers, G2,-see Figs. 2 and 3-to which is
furnished the requisite amount of air by means of pipes, 9', which also extends
back through the combustion chamber to the outer air, where they take in
the desired quantity of air. These side walls, C³, are also provided with
perforations, c, which communicate with the fire box at a point above the point
of combustion, so that the air entering the fuel chamber through such apertures
or openings will readily commingle with the heated gases. These side cylindrical
air chambers, G2, are connected with each other at the front of the fuel
chamber by means of a pipe, G4, which is preferably embedded in the fire brick
front, A2, of the furnace, and which is provided with perforations or openings, g³,
which communicate with the fuel chamber and are used for the purposes herein-
after described.
The structure of the fire box, as hereinbefore described, is such that when the
combustion or distillation of the fuel is taking place and the requisite amount of
air cannot be furnished through the ash pit; or-as in some instances when
the air is furnished through the ash pit, carbonic oxide is formed which is
practically incombustible. A large quantity of heated gases will thus be formed
and pass out through the smoke stack without being consumed, owing to the
fact that they cannot obtain the requisite amount of oxygen necessary to promote
their combustion. It will be seen that I have devised means by which the
requisite amount of oxygen may be furnished by the atmospheric air, which is fed
in through the combustion chamber and heated to such an extent that when it
enters the fuel chamber or fire box it is in such condition that the heated gases
take up the requisite amount of oxygen, at a point where combustion is most
likely to take place, and pass over the fuel bridge wall and out of the fuel
chamber contacting the lower portion of the boiler-back through the second
bridge wall, where the great body of flame is broken into smaller particles heating
this bridge wall into an incandescent heating. The heated gases and products of
combustion pass into the combustion chamber, always being kept in contact with
the lower portion of the boiler, where they are allowed to develop to the maximum
amount before they pass into the tubes of the boiler towards the front and into the
up-take, to be delivered to the smoke stack. This construction alone provides for
a high efficiency in combustion of fuel, and a high rate of economy, as well as

page_text: preventing the formation of smoke, which, as is well known, when it is once
formed, is practically incombustible.
To insure still higher efficiency and economy in the use of our improved furnace,
we provide, preferably, the upper front corner of the fire box with a steam retort, I,
preferably made of hydraulic metal tubing, and provide it with a series of pointed
nozzles, i, which extend through the air retort, G4, in a direction towards the fuel
bridge wall. This retort-which we will term the steam retort-is surrounded
and preferably embedded in the body of refractory material or fire brick, which
may be made in sections, as desired, for the purpose of readily taking out the two
retorts embedded therein and replacing or renewing them whenever it is deemed
necessary. For the purpose of furnishing the steam retort with a supply of steam
at boiler pressure, we connect it to the steam dome, A³, of the boiler by means of
a pipe, 2, which may be provided with an ordinary valve for the purpose of
regulating the amount of steam furnished from the boiler to the retort, thereby
allowing the retort to be filled with steam when desired. The use of this retort
is as follows: Steam at boiler pressure is admitted to it by opening the valve, i,
where it becomes highly heated and is injected across the body of hot incandescent
coals, where it becomes decomposed and hydrogen gas is liberated. The immense
force with which this steam is injected across the fuel of the boiler impels the
hydrogen and heated gases against the bridge wall and heats it to a very
high heat.
It also serves to act as an ejector for the air chamber, G', and drives
out into the fuel chamber a larger amount of atmospheric air than would ordinarily
enter the furnace from such air chamber, so that when it enters the furnace and
the hydrogen gas is liberated, the oxygen immediately mingles with the same or
the distilled gases from the burning fuel, and the highest order of combustion
thereby takes place. Our furnace is so constructed and arranged that the various
channels for furnishing the supply of air necessary to support combustion can be
used as desired. When the fire is first started, and green fuel is being burned, a
larger quantity of air is needed-owing to the fact that larger amounts of gases
are being formed-than when the coal has become coked. In most cases all of
the channels may be opened, and when coked, or partially burned, closed to admit
only enough air to support combustion.
"
The operation of our improved furnace is as follows: Fuel is supplied to the
grate bars in the usual manner, and, after ignition, the requisite amount of air is
furnished to the ash-pit by the usual openings in the door of the same until the
fire gets fairly started, then all of the channels may be opened to furnish the extra,
and generally needful, supply of air. When the fuel has attained a very high
degree of heat, steam is admitted, preferably from the boiler, to the steam retort
in the fuel chamber, where it becomes highly heated and is projected through the
nozzles of the retort across a mass of incandescent fuel in a gaseous state-the
steam having been decomposed and hydrogen gas liberated. The immense force
thereby given forth from this retort throws the highly heated gases against the
bridge walls, and serves to heat them to a state of incandescence. The hydrogen
up the requisite
gas and heated gases before passing over the fuel bridge wall take
amount of oxygen to support their combustion, which is furnished from the air
chamber in this bridge wall. They then pass off in their highly heated state
through the second or perforated bridge wall, B,-which they, in turn, heat to a
high heat and which acts as a reservoir for the surplus beat-back into the com-
bustion chamber, where a more perfect combustion takes place and the flame is
allowed to develop. From the combustion chamber the heated gases and products
of combustion pass in through the back of the boiler, through the tubes to the
front, and out to the smoke stack. By this time the gases are nearly consumed, so
that very little but the products of combustion are carried into the smoke stack.
As the flames expand in the combustion chamber, they contact with the series of
metallic air tubes which connect the air chambers with the outside air and highly
heat the same, so that the air which passes from the outside to the air chambers is
heated to a very high degree before it reaches such air chambers, and is passed

page_text: into the furnace to be mixed with the heated gases. This preliminary heating of
the air serves to assist the combustion of the gases, and does not act to check or
lessen the degree of heat of the flame or gases as they commingle with the air to
take up its quantity of oxygen.
In Figure 4 we have shown the method of applying our improvement to what
is known as a "safety tubular boiler," in which K is the fire box, K' the ash
chamber, and k, ka supporting grate, similar to that shown in Figs. 1 and 2.
Located above the fire box, and at an angle of about 20 degrees, are a set of
water tubes, L, arranged in staggered relation to each other and connected at
the front end with an upper water drum, L', and at the back end with a stand
pipe, L2, which is also connected to the water drum, and, by means of the pipe L³,
with a steam drum L.
.
We will not here enter into a general description of this tubular boiler, as it
forms no particular part of our invention; but merely enough of it to show how
our invention may be applied thereto.
In applying our particular improvement, we provide a wall, M, at the rear of the
fire box, with an air chamber, M', having communication with the outside, by
means of the pipe, m, which extends through the combustion chamber, m', and
which may be provided at its outer end with caps to regulate the admission of the
required amount of air. The air chamber, M', in the first bridge wall, M, com-
municates with a cylindrical air chamber, N; in the fuel bridge wall, N', which
immediately surrounds the fire box, by means of the perforation n, and with the
fuel chamber by means of the perforations, n', which enter such chamber, preferably
at a point slightly above the point of combustion.
The side bridge wall, which surrounds the fuel chamber, is also provided with a
continuation of the cylindrical air chamber, N, to which is also furnished the
requisite amount of air from such chamber, and is also provided with a number of
perforations, n', as is the bridge wall at the back of the fire chamber, so that the
air which is furnished to the fire box is furnished at a point above the point of
combustion. These side cylindrical air chambers are also connected with each
other at the front of the fuel chamber by means of a pipe, O, which is preferably
embedded in the fire brick front, O', of the furnace, and which is also provided
with perforations or openings, o, which communicate with the fuel chamber and are
used for the purpose hereinafter described. The construction of this fire box is
almost identically the same as that described in connection with Figs. 1, 2 and 3,
so that the action which takes place is identically the same, and it would, therefore,
be superfluous to again describe it here.
To still further ensure the efficiency of this style of furnace, as above described,
the upper front part of the fire box is provided with a steam retort, P, preferably
made of hydraulic metal tubing and provided with a series of nozzles, P, which
extend through the air retort, O, in the frout of the fuel bridge wall. This retort
is preferably connected with a steam dome, L, of the boiler, by a pipe, P1, which
furnishes the requisite supply of steam at boiler pressure, and is preferably
surrounded with fire brick or refractory material for the purpose of protecting it
from the intense heating action of the fuel chamber, and at the same time maintain
the uniformity of heat.
The use of the retort is the same as that described in connection with the boilers
shown in Figs. 1, 2 and 3, and is as follows: Steam at boiler pressure is admitted
to the retort, where it becomes highly heated, or to the same temperature that the
fire brick of the furnace is, and is injected into the fuel chamber across the body
of hot incandescent coals, where it becomes decomposed and hydrogen gas is
liberated. The immense force with which this steam is injected across the fuel
chamber impels the hydrogen, heated gases aud air from the cylindrical chamber, O,
against the bridge wall, where it is heated to very high degree.
To the rear of the fire box, we provide what has been termed a combustion
chamber, m, and in this combustion chamber place a bridge wall, R, the lower
portion, which is of ordinary fire brick or fire clay, resting upon the earth. This

page_text: bridge wall is formed of a structure composed of a circular layer of fire bricks,
having cylindrical perforations or openings, r, which extend clear through the
bridge wall. These cylindrical and vertical openings may-if desired-be connected
with each other and with vertical openings, so that the heated air and gases may
freely circulate through the same and pass into the lower portion of the combustion
chamber.
The operation of this furnace, as shown in Fig. 4, is as follows: Fuel, as in the first
instance is supplied to the furnace and igni ed. When the fuel has attained a high
degree of heat, steam is admitted--preferably from the boiler-to the steam retort
in the fuel chamber, where it becomes highly heated and is projected through the
nozzle across the mass of heated fuel in a gaseous state. The immense force
thereby given throws these highly heated gases against the bridge wall and serves
to heat and retain them in a state of incandescence. The liberated gases pass over
the bridge wall and through an opening, R', into the combustion chamber, where a
portion of them pass through the second bridge wall, I, to the rear of the boiler,
and out through the openings, S and S', int, the smoke stack.
We will not enter into a detailed description of the actions and reactions of the
gases which takes place in this furnace, as we have already described the same
fully and in detail in connection with Figures 1, 2 and 3-Fig. 4 being shown and
described merely to illustrate how my invention may be applied to other boilers
than that shown and described in connection with Figs. 1, 2 and 3.
'
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that
what we claim is :-
1. In a boiler furnace, the combination of a furnace provided with a fuel
chamber, a combustion chamber, a perforated bridge wall located between such
chambers, and pipes for furnishing a supply of air through the combustion
chamber to such fuel chamber above the point of combustion, substantially as
described.
2. In a boiler furnace, the combination of a furnace provided with a fuel
chamber, a bridge wall in such chamber provided with an air chamber having
communication with the outside air and perforations which extend into the fuel
chamber for the purpose of furnishing a supply of air to the fuel chamber
above the point of combustion, and a combustion chamber to the rear of such
bridge wall immediately under the boiler proper, substantially as described.
3. In a boiler furnace, the combination of a furnace provided with a fuel
chamber having a bridge wall, a combustion chamber, a perforated bridge wall
separating such chambers, an air chamber in the bridge wall surrounding the
fuel chamber, and pipes to furnish a supply of atmospheric air to the chamber
in the fuel bridge wall and passing through the combustion chamber, substantially
as described.
4. In a boiler furnace, the combination of a furnace provided with a fuel.
chamber, a combustion chamber, a perforated bridge wall between such chambers,
a wall surrounding the fuel chamber and provided with an air chamber having
communication with the fuel chamber above the point of combustion, means for
furnishing a supply of atmospheric air to such air chamber in the fuel bridge wall,
and a steam retort located in the bridge walls of the fuel chamber connected with
the boiler proper and provided with a series of nozzles which extend out towards
the bridge walls for the purpose of expelling superheated steam across the burning
fuel, substantially as described.
5. In a boiler furnace, the combination of a furnace provided with a fuel
chamber, a steam retort lccated in the fuel chamber provided with a series of
nozzles, a refractory jacket surrounding the retort and nozzles and made of fire
brick, and a pipe connecting the chamber of the retort with a source of steam
supply, substantially as described.
6. In a boiler furnace, the combination of a furnace provided with a fuel

page_text: chamber, a wall surrounding such fuel chamber, a cylindrical air chamber in such
wall having perforations extending into the fuel chamber at a point above where
combustion takes place, a main air chamber, G, in such wall communicating with a
portion of the cylindrical air chamber, G', and pipes leading in through the com-
bustion chamber to furnish a supply of air to such air chambers, substantially as
described.
7. In a boiler furnace, the combination of a furnace provided with a fuel
chamber, a wall surrounding such chamber and provided with a cylindrical air
chamber having communication with the fuel chamber pipes to furnish a supply
of air to such air chambers, a steam retort having steam connection with a source
of steam supply located at the front of such fuel chamber, and a series of nozzles
for such steam retort extending out towards the rear wall of the fuel chamber and
led through a portion of the cylindrical air chamber to assist in expelling air into
the furnace, substantially as described.
Dated this 14th day of August 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.