Improvements in or relating to Furnaces.
Year: 1898

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Furnaces.
A communication from ORLAND DORE ORVIS, of 1331, Monadnock Buildings,
Chicago, State of Illinois, United States of America.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered l'atent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to a furnace of the kind in which provision is made for
producing complete combustion of the fuel by means of an arch extending across
the fuel-chamber, spanning the grate and having a discharge-passage. at one
side only of the arch at a point between its lower end and the grate-surface, where-
by the products of combustion, in escaping from the furnace, are conducted to an
updraft passage without passing them downwardly through the incandescent fuel,
but in a manner to bring them rapidly into contact with incandescent fuel on
the grate-bars immediately prior to their escape.
The object is to improve the furnace of the general type thus outlined, in the
directions of causing more perfect combustion of the fuel and maximum utiliza-
tion of the heat for steam production, as well as to enhance the economy of con-
struction and render it easy and quick and comparatively inexpensive to repair.
In the drawings:-
Figure 1 is a longitudinal section taken on irregular line 1 of Figure 2 showing
a steam-boiler furnace constructed with the present improvements with one form
of construction at the bridge-wall; Fig. 2, an enlarged cross-section taken on
irregular line 2 of Fig. 1 showing another form of construction at the bridge-
wall; Fig. 3, a broken section taken. on line 3 of Fig. 2, the construction at the
bridge-wall being the same as in Fig. 2; Fig. 4, an enlarged broken section
taken on line 4 of Fig. 3; Fig. 5, an enlarged section of an arch, taken on line 5
of Fig. 1; Fig. 6, a perspective view of one of the blocks or slabs employed in
the arch construction; Fig. 7, a broken section showing one of the side-grates
employed; and Fig. 8, a section on line S of Fig. 7.
A, A are the side walls of the furnace; B, the front wall or face; C, the rear
wall; and D, the bridge wall. E is a boiler which may be of any desired con-
struction. F is the ash-pit, and G the fire-chamber.
In the fire-chamber G are, preferably, two arches H, H, extending from the
front of the fire-chamber to the bridge-wall. These arches are of the same form
in cross-section,. and are separated by an up-draft passage H¹. Each arch is
formed with. two lower tubes or cylinders t, t, and an upper tube or cylinder 2,
supported at their rear ends in the bridge wall, and at their forward ends in the
front wall. From the said forward ends, toward the lower sides, extend tubes t
which project beyond the face of the furnace and are closed with screw-caps or
plugs Adjacent to their forward. ends the tubes or cylinders t¹ and are
provided with upward extending pipes which connect with a three-way union s¹

page_text: from which extends a pipe s2 to the front end of the boiler. In the construction
shown in Fig. 1, the tubes extend at their rear ends to a water-head or
chamber H2, mounted in the bridge-wall. Extending from the rear ends of the
tubes and, in the construction shown in Figs. 2, 3 and 4, are pipes r which
connect with a three-way union rl from which extends a piper passing through the
rear wall C and closed at the end with a removable cap or plug t A pipe
extends from the pipe 2 into the rear end of the boiler E. In the construction
shown in Fig. 1, the pipe communicates directly with the water-head H². The
tubes or cylinders tt form the lower side supports of the respective arch to which
they belong, the tube 2 forming the ridge. The body of the arch is in sections
comprising blocks or slabs I of fire-clay or other highly refractory heat-storing
material. They are preferably of the form shown most clearly in Figs. 5 and
6 having concave side edges q to fit closely over the tubes or cylinders against
which they rest, and smooth end-faces q¹. The blocks I may be changed in form
as desired, but when placed in position, as shown, they should fit closely against
the front and rear walls and against each other to form an arch sufficiently tight
to prevent the passage of any products of combustion except beneath the tubes
or cylinders to the updraft passage H¹.
Resting upon a sill or shelf p at the front wall and upon a sill or shelf 1 at
the bridge-wall, are parallel angle-iron supporting-beams p², the outer edges of
which should, in practice, be in direct vertical line with the inner edges of the
tubes or cylinders t, as shown in Fig. 2. Resting in the supports p² is a plate p
which extends approximately the full length of the supports, and is formed in
one piece or of closely fitting sections. KK are grates extending longitudinally
of the supports 12 and preferably in two sections as shown in Fig. 1, resting at
adjacent ends on cross-bars a. At the outer edge-portions of the grates K are
upward inclined grate sections forming side grates K¹, as shown in Fig. 2. The
grates K extend in the plane of the plate 3, and are of a width equal to, or nearly
equal to, the distance between the adjacent sides of the cylinders ; the
inclined grates K' extending from the edges of the grates K to the side walls of
the furnace.
In operation the fuel is fed through the door y and spread over the surfaces
of the grates in a usual manner, the hot products of combustion therefrom rising
under the arches H and escaping beneath the tubes or cylinders to the updraft
passage H, whence they spread under the surface of the boiler, pass backward
over the bridge-wall, and thence forward through the boiler-flues to the chimney-
flue X. The draft from the ash-pit, to support combustion, carries the products
of combustion from the burning bed of fuel in the upward direction, to fill the
spaces beneath the arches, whence, owing to the direction of the draft, they are
whirled downward against, or in close proximity to, the incandescent bed of
fuel along the inner edges of the grates K, causing approximately complete com-
bustion. The blocks I, forming the body-portions of the arches, having high
heat-storing properties tend, when once thoroughly heated, to facilitate decom-
position of the products of combustion beneath the arches; and, in the present
construction, to aid combustion in the upper portion of the spaces beneath the
arches, it is preferred, wherever practical, to provide draft-passages L in the
bridge-wall extending from the ash-pit to the rear end of the fire-chamber beneath
the arches. The draft-passages L terminate in preferably horizontal narrow
elongated openings L' formed in metal plates or blocks set into the bridge-wall,
as shown in Fig. 3, the openings tapering in the direction of the fire-chamber
to increase the force of the draft which is thus thrown far forward in the fire-
chamber, supplying air to support combustion throughout the upper part of the
spaces beneath the arches. It is found, in practice, that the draft-openings L'
aid materially in effecting complete combustion.
It is preferred to construct the bridge-wall of or substantially of the crescent
shape shown, whereby the space between it and the boiler is largest below the
center of the latter and becomes gradually reduced toward the upper end at the

page_text: sides of the boiler. Thus the greatest draft will be below the central portion of
the boiler, instead of at the sides, as is commonly the case, and it is found in
practice that there is very material gain in steam production by this construction.
By preference the arches are given a slight downward inclination from the
front to the rear of the fire-chamber. The circulation of water from the boiler
is downward through the pipes 3 and water-head H³, or pipes r, thence through
the tubes or cylinders tt 12, and thence through the pipes ss back to the boiler.
Where a water-arch comprising a single chamber is employed, the capacity of
the chamber is so much greater than the pipes passing to and from it, that the
circulation through the chamber is necessarily slow, whereby over a very hot fire
steam may be produced so rapidly therein as to tend to create a back-pressure
against the inlet-pipes and retard the circulation. The tubes or cylinders t t¹ (2
have all the capacity necessary to cause the water passing through them to be
raised to the desired high temperature, and effect rapid circulation without
danger of creating a back-pressure against the water entering at the pipes 2.
The pipes employed in the construction in Figs. 2, 3 and 4 and the tubes t³
join the cylinders near the lower sides of the latter. By removing the screw-caps
or plugs, brushes or scrapers may be readily inserted and passed along the base-
portions of the cylinders and through the pipes to clean them when desired.
r
By employing the supports p2 and plate pa center wall is dispensed with in
the ash-pit which would not only increase the expense of construction, but also
interfere more or less with the air currents in the ash-pit.
The inclined side-grates K¹ prevent the undue accumulation of fuel along the
outer edges of the grates, their tendency being to cause the fuel, as it is fed, to
roll or slide toward the center. Furthermore, they tend to produce a more or
less horizontal side-draft which stirs up the products of combustion in a way to
greatly facilitate combustion.
The plate 23, and its supports 23, operate as a draft deflector to prevent air
currents from entering the up-draft passage without first rising in the spaces
beneath the arches. By supporting the deflector as stated the central wall
usually provided in the ash-pit is dispensed with. This wall not only adds to
the cost of construction, but, by separating the currents entering the furnace
to supply combustion, it is apt to render the currents, which flow to the two
grates respectively, unequal in volume, thereby causing unequal combustion.
In this improved construction the deflector has a clear space beneath it for the
circulation of air throughout the ash-pit, whereby the objections to the presence
of the wall is overcome.
The arches H constructed as described are a very desirable improvement. The
tubes ttt form circulating conduits which are always filled with water and
practically indestructible, being rendered so, more especially, by providing them,
first, of a capacity not too great to permit the water heated or steam generated there-
in to pass readily through the pipes 2 to the boiler, and, second, by inclining them
as described, whereby the tendency of the current under the pressure generated
in the tubes will be in one direction to maintain a constant circulation The blocks
or sections I, forming the body portions of the arches, store the heat and tend to
neutralise the chilling effect produced by the circulating tubes upon the hot
products of combustion which rise under the arches. When it is desired for any
reason to replace any of the sections with new ones this may be done quickly
and easily without disturbing the tubes or the other sections.
The invention is not limited to the employment of two arches; and, if desired,
two, only one, or more than three tubes may be provided in the arch to effect
the desired circulation. It is preferred, however, to employ two arches of the
form shown, each constructed with three tubes, or water conduits, mounted as
stated, and capable with their pipe connections of maintaining a circulation of
sufficient volume and rapidity through the boiler to prevent deposits, and conse-
quent formation of scale, upon the boiler sheet and flues.
To adapt the present improved furnace to the well-known Galloway boiler, the

page_text: furnace should. De punt entirely forward of the boiler and properly connected
with it.
This invention is not confined to use in connection with a steam generator,
nor when so employed, to any particular form of generator; and while it is
preferred to construct the improvements throughout as shown and described,
they may be variously modified without departing from the spirit of the invention
as defined by the claims.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent and in what
manner the same is to be performed, I declare that what I' claim is;-
1—In a boiler-furnace, the combination of a grate, an arch inclining down-
ward in the backward direction and spanning said grate, and a discharge passage
at one side only of said arch and in a plane between the lower edge of the arch
and upper surface of said grate, the arch being formed of a frame, comprising
longitudinally extending water circulating tubes in communication at opposite
ends with the boiler, and a body-portion of refractory material supported upon
the frame and filling out the space between said tubes, substantially as described.
2-In a boiler-furnace, the combination of two grate-surfaces. separated by a
close longitudinally extending bed, an arch spanning each of said grate-surfaces,
an updraft passage between the arches above said bed, discharge passages at the
adjacent sides of said arches only leading to the updraft passage, the arches being
formed of frames, comprising longitudinally extending water circulating tubes
in communication at opposite ends with the boiler, and body-portions of refrac-
tory material supported upon the frames and filling out the spaces between the
tubes, substantially as described.
3-In a boiler-furnace, the combination of two grate-surfaces separated by a
close longitudinally extending bed, an arch spanning each of said grate-surfaces,
an updraft passage between the arches above said bed, discharge passages at the
adjacent sides of said arches only. leading to the updraft passage, the arches
being formed of frames, having parallel longitudinally extending water circu-
lating tubes tt t², inclined downward in the backward direction, and in com-
munication at opposite ends with the boiler, and body-portions of refractory
material supported upon the frames and filling out the spaces between the tubes,
substantially as described.
4-In a furnace, the combination of an arch, comprising longitudinally extend-
ing water circulating conduits and a body-portion formed of sections of refrac-
tory material fitting against and supported by the conduits, a grate surface
spanned by said arch, and a discharge passage at one side only of said arch and
in, a plane between the lower edge of the arch and said grate surface, sub-
stantially as and for the purpose set forth.
5 In a furnace, the combination with the ash-pit and two parallel companion
arches separated by an updraft passage and having outlets at their adjacent lower
sides only communicating with said passage, of a grate below each said arch and
spanned thereby, and a draft deflector between the grates centrally beneath said
passage and extending longitudinally above the ash-pit, the deflector being sup-
ported to leave an open air circulating space beneath it, and being of a width not
less than the distance between the inner lines of the adjacent edges of the arches,
substantially as and for the purpose set forth.
6- In a furnace, the combination of an arch, closed at the rear end, a grate
surface spanned by said arch, a discharge passage at one side only of said arch
and in a plane between the lower edge of the arch and said grate surface, a feed
opening for fuel at the front end of the space covered by the arch, and a draft
opening at the rear end of the said space above the plane of the said discharge
passage, substantially as and for the purpose set forth.
7-In a boiler furnace, the combination with a horizontally disposed cylindrical
boiler, of: a fire-chamber below one end portion of the boiler, and a bridge-

page_text: wall at the end of said fire-chamber, of substantially crescent shape
at its upper edge, whereby it extends below and up opposite sides
of the boiler, and the space between it and the boiler is largest below the
center portion of the boiler, substantially as and for the purpose set forth.
Dated this 3rd day of October 1898
BOULT & WADE,
Agents for the Applicant.