Improvements in Furnaces for Steam Boilers.
Year: 1894

page_text: Date of Application, 7th Aug., 1894-Accepted. 3rd Aug.. 1805
COMPLETE SPECIFICATION.
Improvements in Furnaces for Steam Boilers.
I, ORLAND DORE ORVIS, of 307 Dearborn Street, City of Chicago, in the
County of Cook and State of Illinois, United States of America, Mechanical
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 steam boiler furnaces in which the fire-chamber is
enclosed by an arch isolating the boiler or other surface to be heated from any cold
air conducted to the fire-chamber for promoting combustion and draft, or
unavoidably admitted thereto while raking down and firing, which arch also isolates
the boiler or other surface to be heated from direct exposure to the bed of incan-
descent fuel on the grate-hars and this whether burnt or refractory fuel is used
thereon.
This invention further relates to the aforesaid arched fire-chamber structures in
which two arches extending lengthwise of the fire-chamber or grate surface have
etween them an up-draft passage extending the entire length of said arches.
The object of this invention is to secure in furnaces of the arched fire-chamber
construction before referred to all of the advantages of perfect combustion common
to down-draft furnaces and all of the advantages of an up-draft furnace without
any of the disadvantages of either; as, for example, the disadvantage of the retarded
draft of a down-draft furnace and the imperfect combustion of an up-draft
furnace.
More specifically stated, the object of this invention is to provide in an arch
enclosed fire-chamber for conducting from without the same to an up-draft passage
the products of combustion evolved and ignited within said chamber and this without
passing them downwardly through the incandescent fuel but in such a manner that
they will be rapidly brought in contact with the incandescent fuel on the grate-bars
immediately prior to their escape so as to thereby insure their more nearly complete
ignition.
Another object is to provide for conducting the products of combustion from a
double-fire-chamber of an arched furnace without passing said products through the
bed of incandescent fuel but in rapid and direct contact therewith and directly to
an up-draft passage lengthwise of and adjacent to and between said fire-chambers
whereby the resultant impinging of the flames and combining of the heat discharged
from both fire-chambers shall ignite all products of combustion escaping from either
of said fire-chambers unignited.
I attain these objects by features illustrated in the accompanying drawings in
which:
Figure represents a longitudinal section of a furnace on line 1-1 of Figure 2
embodying my invention, showing its use in connection with a steam boiler.
Figure 2 is a transverse section of the same on line 2-2 of Figure 1.
Figure 3 is a longitudinal sectional view on line 3-3 of Figure 4, of a steam
boiler furnace embodying my invention wherein the fire-chamber is enclosed by a
water arch connected with the boiler, and
Figure 4 is a transverse section of the same on line 4-4 of Figure 3.
Similar letters of reference indicate similar parts in the several figures of the
drawings.

page_text: A A indicate the side walls of a furnace of the usual construction provided with
an ordinary door or doors B, ash-pit door or doors C. and one or more grate-
surfaces D, which grate-surfaces are separated by a wall E rising from the bottom
of the ash-pit to a plane with the upper surface of the grate bars and extending
from the front wall of the furnace to a bridge wall F, but it would be no substantial
departure from my invention to omit the wall E and have the grates contiguous to
each other.
As shown in the drawings the grate surfaces are spanned by arches G closed at
their rear ends by the bridge wall F which said arches join the side walls A A of
the furnace, but at their opposing sides are separated by an updraft passage H
which extends the length of the arches or fire-chamber and is adjacent thereto and
is the common and only updraft passage for the products of combustion of both fire
chambers.
These arches are supported in their operative positions in any suitable manner,
as, for example, at one end by the bridge wall and at the other end by the front
wall of the furnace, and are closed at their rear ends by the bridge wall F as shown,
but may have closed ends of their own.
Between the adjacent side edges or bases of these arches and the grate-bar
surface is a discharge passage I through which the products of combustion are
discharged from the fire-chamber into the updraft passage which said discharge
passage preferably extends the entire length of the fire-chamber and is of such a
depth as to permit a free discharge of the products of combustion from the fire-
chamber to the updraft passage and at the same time deflect said products against
the incandescent fuel adjacent thereto to insure as nearly as possible the ignition of
such products by contact with the surface of incandescent fuel, or, in other words,
to pass said products over the surface of the incandescent fuel in sheets sufficiently
thin to insure their ignition to the highest degree consistent with a perfect freedom
of their discharge from the fire chamber to the updraft passage, and also to prevent
cold air admitted to the fire chamber in firing from chilling the crown sheets of the
boiler or other surface to be heated, and any substantial volume of ignited products
escaping from the fire chamber to the updraft passage.
In Figures 1 and 2 the arches are shown of a solid construction with the outside
bases of the arch supported by ledges a in the furnace wall and at their inner edges
by bars which may be embedded in the arch structure to better protect them from
the destructive influence of direct heat, but said arches may be supported in any
other suitable manner and be constructed of any material commonly employed or
adapted for such purposes.
In Figures 3 and 4 the arches are of a hollow construction, preferably of steel,
but may be of any other material so as to form a water chamber constituting a
water arch e over the fire-chamber and connected with the boiler by pipes de at
opposite ends thereof as shown in Figure 3, so arranged that a perfect circulation
of water between the arch and boiler is maintained, and the arches utilized as a
supplementary heating surface for water.
The employment of the water arch in the manner shown and described is however
the preferred construction for steam boiler purposes for the reason that the water
heating surface of the steam boiler furnace is materially and substantially increased
and the direct heat of the fire-chamber is utilized for heating boiler water without
any ossible injury to the boiler, and besides, such a circulation of water is
maintained in the boiler that injurious precipitations and coating of the boiler
thereby are substantially less than when no circulation exists.
In the practical operation of my furnace with an incandescent bed of burning or
refractory fuel on the grate surfaces the products of combustion evolved or ascending
through said incandescent bed as may be, rise in the chamber formed by the arelies
and then, owing to the draft, are caused to descend through the discharge passage
and impinge against each other in the updraft passage H, the depth of the discharge
passages, as before stated, being such that as far as possible all unignited products

page_text: shall be brought in contact with the surface of the incandescent bed of fuel
immediately prior to their discharge through the passages 1.
An extended practical operation of my furnace, however, demonstrates that a
maximum degree of rapid draft is not secured without a small portion of the
products of combustion escaping unignited from the fire-chamber, but that by
having the flames of double fire-chambers impinge in the updraft passage as before
described and particularly at the moment of their discharge from the fire-chamber,
a degree of heat is produced through which none of the products of combustion
can escape without being ignited, and hence, that by the use of the double fire-
chamber structure with an updraft passage common to both and arranged between
and lengthwise of said chambers, the result is absolutely complete combustion with
a maximum rapid draft in the presence of each other, and, therefore, that I am
enabled by my furnace to supply heat to a steam boiler or other surface to be
heated to the best advantage and with maximum economy.
In this connection it is proper to observe that this advantage and economy
accrues to the use in the fire-chamber of liquid and gaseous fuel as well as solid
fuel as will be understood by bearing in mind that ignited products of combustion
whether from solid liquid or gaseous fuels, will, when ignited, rise in the fire-
chambers and descend thence through the discharge passages thereof and impinge
against each other in the updraft passage precisely the same, and therefore that in
the operation of my furnace with any of these fuels, complete combustion in the
presence of rapid draft being the result, my invention is not limited to the use of
burning fuel on the grate bars as might possibly be inferred from the construction
shown.
While the double fire-chamber structure and the intermediate updraft passage
common to both has the advantage of diffusing the heat from the center simul-
taneously to both sides of the surface to be heated and also that of such an
impingement of the heat and flames of both fire-chambers as to render combustion
absolutely complete, it would be no departure from my invention to employ a single
arch fire-chamber with a draft passage adjacent to and extending lengthwise of one
or both sides thereof, nor to have a fire-chamber discharge-passage between the
grate surface and the end edge of an arch euclosing the fire-chamber in a furnace
wherein the updraft passage is at the rear end of said fire-chamber, for my invention
includes any single or double arch enclosed fire-chamber construction provided with
a discharge passage therefor substantially below the apex crown or top of said
chamber and in a plane with or above the grate surface.
A prolonged practical operation of my invention as embodied in Figures 3 and 4
of the drawings herewith, demonstrates it to produce absolutely perfect combustion
as nearly as may be, that the natural draft in and through the fire-chamber is
substantially as rapid as in any updraft furnace, that it will burn the cheapest soft
coal and waste coal withcut producing smoke at the chimney, that it will diffuse a
greater number of a given number of units of heat over the surface to be heated
with better effect than any other structure even when such other structure is
provided with an artificial or forced draft, that it will more quickly heat and
evaporate a greater number of pounds of water with a pound of coal than any
other.
In conclusion it may also be observed that in a furnace of my invention the draft
and the application of heat to the steam boiler is so full and complete that there is
so little radiation of heat against the front of the furnace and even from the fire-
chambers during firing that a fireman experiences no discomfort when standing even
for an unusually prolonged time immediately in front thereof, when with all other
furnaces so heretofore employed the radiation of heat from the front of the furnace
when standing at the same distance is unbearable for a comparatively short time,
and the importance of this absence of radiation from the front of a furnace
embodying my invention increases as the number of furnaces are increased in the
battery, and as unavoidably or otherwise ventilation in the boiler room is
decreased.

page_text: 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. In a furnace for steam boilers, the combination of an arch, a grate surface
spanned by said arch and a discharge passage at one side only of said arch and at a
point between the lower edge of the arch and said grate surface, substantially as
described.
2. In a furnace for steam boilers, the combination of two or more arches, grate
surfaces therefor spanned by said arches, discharge passages at one side only of
each of said arches and at a point between the lower edges thereof and their
respective grate surfaces and an updraft passage adjacent to said discharge passages,
substantially as described.
3. In a furnace for steam boilers, the combination of arches arranged side by
side, grate surfaces spanned by said arches composing discharge passages at one
side only of said arches at a point between the lower edge thereof and the grate
bar surface, an updraft passage extending lengthwise of and between the arches
and a wall rising from the bottom of the ashpit to a plane with the grate-surfaces
and separating said grate surfaces, substantially as and for the purpose described.
4. In a furnace for steam boilers, a double fire-chamber embracing individual
grate bar surfaces, circulating water arches enclosing the fire-chamber, an updraft
passage lengthwise of and between said arches and a steam boiler connected with
said arches, in combination with a fire-chamber discharge passage directly connected
with said updraft passage, which said discharge passage is substantially below the
crown or top of the fire-chamber and in a plane with or above the grate-bar surfaces
whereby a water-arch furnace structure is subjected to the heat of perfect
combustion in the presence of a maximum degree of rapid draft, substantially as
described.
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ORLAND DORE ORVIS.
Haseltine, Lake & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.