Improvements in Furnaces and in Steam Boilers used in connection therewith.
Year: 1892

page_text: Date of Application, 29th Nov., 1892-Accepted, 28th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in Furnaces and in Steam Boilers used in connection
therewith.
A communication by FRANK BARCLAY, of. Beatrice, in the State of Nebraska,
United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, and 323, High Holborn, in the
County of Middlesex, Civil 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 :-
This invention relates to furnaces for steam boilers and the like, and the invention
consists in certain novel features of construction as hereinafter more fully
described.
Figure 1 is a side elevation of part of a stationary boiler and furnace with the
side wall removed to more fully show the internal construction.
Figure 2 is a vertical section on the line -x of Figure 1.
Figure 3 is a horizontal sectional view through a locomotive fire box arranged
in accordance with this invention :
Figure 4, a vertical sectional view on the line 2-2 of Figure 3:
Figure 5, a vertical transverse sectional view on the line 3-3 of Figure 3: and
Figure 6, a vertical transverse sectional view on the line 4-4 of Figure 4.
This invention relates to that class of furnaces in which a double fuel chamber
is used, the fuel first being coked in the coking chamber, and then with the gases
consumed in the second or combustion chamber.
Referring first to Figures 1 and 2, which show the invention applied to a
stationary boiler :-
B represents an ordinary tubular boiler set in brick work A, with a bridge
wall D, in the usual manner.
The fuel chamber, however, is divided into two chambers, a front or coking
chamber E, and a rear or combustion chamber F, as shown in Figure 1, each
chamber being provided with a set of grate bars G, the adjoining or abutting ends
of the two sets being supported by a cross bar o, which has a bearing at its ends in
the side walls and which may also have a central support, if necessary.
A water pipe or box C is provided of the proper length to reach across the
furnace chamber and rest upon the side walls, as shown in Figures 1 and 2, it being
connected to the boiler B by pipes p and r, as shown, to permit a free circulation
of the water to and from the boiler. This may be made of cast or wrought iron,
as preferred. This water pipe may be round as shown in cross section, or of any
form that will support the fire brick used to form a combined air duct and
partition between the two chambers E and F.
On this water pipe C is placed a set of fire brick m, which is moulded with a
recess in its lower face to fit on the pipe, (if a circular pipe be used) and on these
are set a front row of fire brick a and a rear set b, the latter being provided with a
series of small perforations, as shown in Figures 1 and 2. These two rows of fire
brick a and b are set some distance apart, so as to form an air chamber or duct e
which is also covered with fire brick, this chamber or duct extending entirely across
the furnace with a door or register at each end to regulate the admission of air
from the exterior. If desired, this chamber may be formed of one or more sections
of fire clay moulded to the proper form, instead of being composed of separate
bricks. The bottom tier m also has a row of perforations, which are inclined as
shown in Figure 1.

page_text: As shown in Figure 1, this forms a partition between the front or coking
chamber E and the rear or combustion chamber F, extending from the top
downward, with a space between it and the gratebars G below, through which space
the coked fuel is shoved from time to time, and through which also all the gases
produced in the coking chamber pass.
The front chamber E is covered with fire brick u, and is provided with a door I
for the admission of the fuel, and below that with a smaller door t for the insertion
of a poker or implement for shoving the coked fuel from the front chamber back
into the combustion chamber, as occasion may require. The ash pit P will also be
provided with the usual doors for regulating the draught as may be necessary.
A section, J, of the rear grate is hinged so as to be movable as shown in Figure 1,
it being provided with an arm which is connected by a rod neto a lever L by
which it can be shaken to remove the ashes, and, when necessary, can be dropped
to remove any clinker that may form thereon.
The operation of the apparatus is as follows:-
A fire is started in both chambers E and F, and, after it is fairly started, the
front chamber is partly filled with coal and the doors closed, the fuel therein
becoming coked or roasted. From time to time, this roasted or coked fuel is shoved
back through the space or throat T into the combustion chamber F, where it is
burned. While this is going on, air from the opposite sides enters the air chamber e
where it is heated by contact with the highly heated fire brick a and b, and from
thence passes in small jets through the perforations in the bricks and is delivered
just over the burning fuel in the combustion chamber F, where it is intimately
mingled with the hot gases arising from the same, and which are still further
heated by passing through the incandescent fuel, thereby causing a perfect
combustion of the gases and smoke. By these means, not only is perfect combustion
secured, but also the smoke is consumed, thereby avoiding a great nuisance,
especially when steam boilers are used in cities or densely settled neighbourhoods.
By roasting or coking the fuel before burning it, greater economy of fuel and a
more intense heat are also ensured.
By arranging the coking chamber in front of the combustion chamber, whatever
gas or smoke is given off in the coking of the fuel is drawn through throat T into
the combustion chamber, where it is brought into contact with the burning fuel
therein, and where, being supplied with oxygen furnished by the jets of heated air
from the air chamber e, it is consumed, and thus utilised to a far greater extent
than is possible in the ordinary single chamber furnace.
Referring next to Figures 3 to 6.
In these―
A indicates the fire box of a locomotive or other boiler, B the grate, and C the
fuel door at the front end of the fire box, the said fire box being provided with
hollow walls as shown for containing water, so as to prevent the sides from burning
out and to give increased heating capacity.
D indicates the retort, which is of substantially an arch shape in vertical cross
section. This retort is applied over the fuel door or opening C, and is closed on
the sides and end as clearly shown in Figure 4. The side and end walls of the
retort are made hollow so as to contain water, the plates forming said side and end
walls being connected by stay bolts a as shown in Figure 4.
This retort is set up above the grate a slight distance as shown in Figures 4, 5
and 6, and is also set away from the inner walls of the fire box proper, as shown in
Figures 3, 4 and 5 so as to afford a space beneath and at the sides and end of the
retort. The retort is connected at its front end with the water space of the fire
box by pipes E; at its rear end by a leg or pipe F, and on its sides by pipes G,
the said pipes E, F and G serving not only to ensure a constant circulation of the
water from the retort to the hollow walls of the fire box, but also assist in
sustaining the retort in its proper position, there being any required number of
these pipes.
The top of the retort is preferably arched or curved as shown in Figures 5 and 6

page_text: and is made up of a series of tiles, slabs or fire brick 6, which are supported at
their outer ends upon the side walls of the retort, as clearly shown in Figure 6.
At the front end of the retort, a door or direct draught valve H is arranged
which is made by mounting one or more of the tiles, bricks or slabs upon a hinge
as shown in Figure 4, so that it may be raised to permit the products of combustion
to pass directly into the main part of the fire box and escape through the flues.
This valve H will be operated by means of a rod or handle I projecting out through
the wall of the fire box at any convenient point.
It will of course be understood that the direct draught door or damper H will be
opened only when the fire is first started, and that, as soon as the fuel is thoroughly
ignited, this door is to be closed and kept closed, thus compelling the gases to
escape from the retort by passing down and under its lower edge, and through the
incandescent fuel.
It is important that a considerable portion of the retort be composed of fire
brick, or that it be lined in whole or in part with fire brick or similar material, for
the reason that the fire brick roof, walls or lining becomes much more highly
heated than would the water filled metallic walls, and therefore much more
effectually cokes the fuel.
If made wholly of hollow walls filled with water, the heat would be constantly
conveyed away by the circulation of the water, whereas, with the fire brick, such is
not the case.
It is obvious that, by using properly formed arch slabs or blocks of fire clay for
the top, they may be made to extend downward on the sides and end to any extent
desired, the metallic walls being made correspondingly narrower, and that, by so
doing, or by lining the sides with fire brick, the coking capacity of the retort may
be increased to any desired extent.
From the foregoing description, it will readily be seen that, when fresh coal is
placed upon the layer of incandescent or hot fuel lying on the grate within the
retort, it will be roasted or coked, thereby liberating the gases from the solid
portion of the fuel in substantially the same manner as in the ordinary gas retort,
and that the gases thus liberated can escape from the retort only by passing out
under the edges of the retort, and that, in so doing, they must pass through the
incandescent fuel which rests on the grate both under the edges of the retort and
in the combustion chamber outside of the retort, whereby they will be highly
heated, and, uniting with the oxygen of the air which enters the outer or combus-
tion chamber, produce a much more perfect combustion than can be produced by
burning the fuel in an ordinary fire box, and consequently producing a higher
degree of heat, with a saving of fuel and a lessening of the smoke.
By using the water pipe as a support for the hollow partition between the front
and rear chambers, the use of an arch is avoided, which, by the unequal expansion
of its parts, would soon destroy the integrity of the air duct. By this means also,
the passage or throat which connects the two chambers is made of uniform height
all the way across the furnace, thereby enabling the fuel to be distributed more
evenly across the entire grate when shoved into the rear chamber; by which means
also the gases from the coking chamber are caused to pass into the combustion
chamber in a thin sheet extending entirely across the furnace, in the best possible
condition to be evenly mixed throughout with the fine jets of the heated air, the
perforations for which also extend entirely across the furnace.
By this construction, the consumption of fuel is reduced nearly one half, as com-
pared with the furnaces now in general use. The arrangement can be modified to
suit other forms of boiler: to show this, Figures 3 to 6 are added, showing it
applied to a locomotive.
'
My correspondent is aware that various forms of chambers have been devised for
partially roasting the fuel before it was consumed, but he is not aware that any one
has before devised a furnace in which the fuel could be thoroughly coked before it
entered the combustion chamber; nor one in which the air is heated and delivered
in a large number of small jets so as to be instantly and thoroughly intermingled

page_text: with the hot gases as they enter the combustion chamber, which latter feature
constitutes a very important element of this invention in stationary boilers, where
the strong draught caused by the rapid motion of a locomotive is wanting.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. In a furnace, the combination of a front coking chamber, a rear combustion
chamber, with a transverse air chamber or duct located in a pendent partition
between the two chambers, the rear wall of said air chamber or duct being provided
with a series of small perforations for the delivery of heated air in small jets,
substantially as and for the purpose set forth.
2. In a furnace, the combination of a front coking chamber, a rear combustion
chamber, a pendent hollow partition located between said chambers and having its
rear wall provided with a series of small perforations, and a water pipe arranged to
support said hollow partition, substantially as described.
3. In a furnace, the combination of a front coking chamber, a rear combustion
chamber, and a pendent partition having an opening underneath it through which
the gases are compelled to pass through the incandescent fuel, with an air heating
duct or chamber located in said pendent partition and having its rear and lower
walls provided with a series of perforations for delivering the air in small jets at the
point where the gases enter the combustion chamber, substantially as shown and
described.
4. In a furnace of the locomotive or marine engine type, a retort composed in
part of hollow walls, and in part of fire brick, said retort being set or arranged
within the fire box and above the grate, substantially as described and shown in
Figures 3 to 6.
5. In a furnace of the locomotive or marine engine type, the combination, with
the fire box, of the retort composed in part of hollow walls connected by tubes with
the boiler, and in part of fire brick or equivalent heat retaining material, and pro-
vided with a direct draught opening and a door or damper for closing the same at
will, substantially as and for the purpose set forth.
Dated this 28th day of November 1892.
WM. P. THOMPSON & Co.,
Agents for the Applicant.