IMPROVE- MENTS IN FURNACES
Year: 1884

page_text: I, WILLIAM PHILLIPS THOMPSON of the Liverpool and London Agency. for
Foreign Patent Solicitors 6, Lord Street Liverpool in the county of Lancaster,
Civil Engineer do hereby declare the nature of the said invention for "IMPROVE-
MENTS IN FURNACES 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 improvements in furnaces more particularly adapted
and bereinafter described as applied to steam-boiler furnaces, in which a bridge wall
is arranged forward of the rear end of the boiler, and the space between the bridge-
wall and the rear end of the furnace forms a combustion chamber for the products
of combustion of the fire-chamber escaping over the bridge wall.
The objects of the invention are to provide such a furnace with a reverberatory
surface, the effect of which shall so augment the heating capacity of the furnace as
to permit a material reduction in size of fire-chamber, and a corresponding reduction
in the amount of fuel necessary to be employed to attain a given degree and area
of heat; to provide means for effectively removing from the reverberatory portions
of the furnace the accumulation of ashes, fine particles of coal, sand, and other
substances which have the effect of diminishing and destroying the reverberating
and reflecting powers of such portions, and to make such removal without cooling
or stopping the operation of the furnace; to provide means for supplying and
regulating currents of air supplied to the products of combustion, to promote
perfect combustion in the combustion-chamber in the rear of bridge wall, and for
utilizing the heat of the furnace for heating said, air currents before contact with
products of combustion; to provide a novel form of bridge-wall which shall afford
the least possible resistance to flames striking against it from passing over into the
combustion chamber, and which wall will also cause the coal, striking against it.
when firing, to bank up against and not rebound from the wall; to provide the
furnace with an ash-pit of a form best adapted for effective cleaning, and for
reverberating the heat deflected from the burning fuel on the grate-bars; to provide
means for dividing the air current upon its entrance to the combustion chamber;
Duine C

page_text: and for closing the outlets during the removal of the accumulated ashes et cetera
from the combustion chamber and ash-pit, and correspondingly reducing the
draught of the furnace to prevent the finer particles from rising and clogging
the flues of the boiler; and finally in details of construction hereinafter described
and claimed.
These objects are attained by devices illustrated in the accompanying drawings
in which
Fig. 1 is a longitudinal section of a steam-boiler furnace embodying my
invention.
Fig 2-is a transverse section of the same on the line y, y of Fig. 1.
Fig. 3 is a similar view on the line x, x, Fig. 1.
Fig. 4 is a detail section of the rear end of the furnace.
Fig 5 is an enlarged perspective in detail of the conveyer and swinging bars
above the same.
Figs. 6 and 7 are respectively a cross-section and plan view of a furnace in which
more than one conveyer is necessary for effective operation.
A, A, represent the end walls, and B, B, the side walls of the furnace, the rear
end wall and the side wall of which are respectively provided towards their top
with a flange or horizontal extension a and b b, from which the boiler C is
suspended by means of suitable angle-irons or anchors c, or other suitable means.
The front end of the furnace is provided with the usual furnace opening D, closed
by a door through which opening fuel is thrown upon the grate-bars E, which bars
are of the ordinary construction and may be supported on an angle iron e, and
projected into the bridge-wall as shown, or in any other usual or desirable manner.
Ash-pit F has its sides protected by linings f,f, (see Fig. 3) which linings extend
above the grate-bars, are convexed on their upper edges, and form linings for the
sides of the fire-chamber, and are removable so as to be replaced by new linings
when burnt out.
The bottom of the ash-pit is removable and inclined from the front towards the
rear of the furnace, and where it joins the bridge walls at g, is concaved with the
bridge-wall so that when an ordinary scraper is introduced the ashes may be
effectually and cleanly, removed, 'which could not be if the jointure of the ash-pit
with the bridge-wall formed an angle.
Inclining and curving the ash-pit in the above described manner is an important
feature of my invention, for the reason that it not only facilitates the removal of
the ashes, but reverberates the heat deflected from the fuel and grate bars causing
a more rapid combustion of the fuel, which together with the reverberated heat
itself materially increases the heating capacity of the furnace.
The reverberatory effects of the ash-pit may be augmented by convexing the
bottom as well as inclining the bottom of the ash-pit, or by convexing said bottom
without inclining it, but the construction shown is preferred on account of its
affording a better surface for removing the ashes and for the scraper to successfully
operate upon.
The ash-pit of course should be provided with a suitable door and with slide for
regulating the draughts not here necessary to be shown.
Bridge-wall G is the bridge-wall proper of the furnace, and is built and arranged
in the usual manner, except so far as broadening and concaving its rear side as
hereinafter described.
His a supplemental bridge-wall conforming in height to the bridge-wall proper
and having close contact therewith, and convexed on its upper corner next the
fire-chamber as shown at h, which convexity terminates just above the grate-bars.
The extremities i of the supplemental bridge-wall which follow the curved
continuation of and rise with the horizontal face of the bridge-wall proper are
concaved, so as to fill in the angle otherwise formed by juncture of the bridge-wall
with the straight side-walls of the fire chamber.
The supplemental bridge-wall effectually protects the bridge-wall proper, and
may be readily removed when burnt out without disturbing the latter.

page_text: Convexing and concaving the supplemental bridge-wall gives it two important
functions, first that of its affording less resistance to and enabling the flames striking
against it or its extension i to glance over and be carried by the draught further
towards the rear of the furnace than if a vertical face and angular corners opposed
the flame, and second, that of affording a surface down which the coal thrown
against the bridge-wall will slide, and bank up against the face of the wall instead
of rebounding as on a straight wall, and afterwards be pushed against the bridge-wall
as is commonly required, and furthermore concaving and convexing the bridge-wall
in this manner gives it a reverberatory effect which is desirable.
I represents the combustion chamber between the bridge wall and rear end of the
furnace, which chamber has concaved so much. of its walls as is below the plane of
the crown-sheets of the boiler (see Figs 1 and 2), or in other words has a concaved
bottom extending up into its side and end walls, which bottom is grooved, and the
rear end wall and the bridge walls of the furnace, are perforated to receive a
concaved trough k, in which is operated a screw conveyor K, journalled in suitable
hangers, and provided on its rear end which projects through the furnace with a
crank L for manipulating the conveyor, the outer end of the trough being closed by
a suitable disc.
This conveyor when operated serves to draw out of the furnace the accumulation
of ashes and fine particles of coal which escape over the bridge-wall into the
combustion chamber, and also the sand and grit given off by the walls of the
combustion chamber by reason of the intense heat to which the walls are subjected.
Concaving the walls of the combustion chamber causes these substances to
accumulate in the conveyor-trough, and not form a layer destroying the rever-
beratory and radiating power as they would do if the bottom of the chamber were
not inclined at a sufficient angle to cause the particles to roll into the trough, and
by the term incline it should be understood that so far as an effective operation of
the conveyor is concerned, the bottom of the combustion chamber may be V-shaped
instead of concave.
.
In this connection it should be stated that the forward end of the conveyor is
closed, and that the shaft of the conveyor may be projected and operated in the
ash-pit instead of at the rear of the furnace.
Arranged in the combustion chamber just above and transversely of the conveyor
are a series of bars M pivoted at their lower edges to the conveyor trough by
means of lugs (see Figs 1 and 5), and at their upper edges by lugs to a rod m.
which passing through is operated from the rear end of the furnace to swing the
bars on the same principle of the slots to a shutter to cut off or open communication
between the combustion chamber and conveyor as the case may be.
These bars are hollow and provided with openings through which air is
introduced into the combustion chamber as hereinafter described, the purpose of
having these openings on the rear side of the bars being twofold, namely, that of
supplying the air in the direction with the draught of the furnace so as not to
impede but augment the draught, and so that the openings may not become filled.
with ashes et cetera coming over the bridge wall during the operation of the
conveyor, at which time the bars are closed upon each other to prevent lighter
particles rising.
These openings may be elongated and extend the length of the bars, or consist
of a series of perforations in each bar, and in either construction the series of bars
serve to divide the air current so that it will effectually commingle with the
products of combustion escaping over the bridge-wall, the pivotal movement of the
bars serving to regulate the volume of the air current or to cut it entirely off as
above described.
Opening upon the rear end of the furnace and formed in the side-walls thereof
are air inlets or chambers N, from which air passages shown in Fig. 2 lead to an
air chamber n, surrounding the conveyor trough, into which air chamber the hollow
|bars open and receive their supply of air,

page_text: Chamber n may or may not be lined as desired by a sheet metal trough N; and
opens at the rear end of the furnace where it is closed by suitable doors O through
which a supply of air may be taken instead of taking it through the walls of the
furnace and heating the air during its passage, or it may be used in connection with
the heated passages to supply an increased volume of air.
Supported by suitable angle irons p resting on the boiler is a boiler covering P
preferably of brick, but may be of any other suitable material, which covering has
an edge support on flat bars q resting upon and extending from one angle iron c to
the other, said bars in fact forming a base support for the cover.
T
Practical experiment with iny furnace has demonstrated that with the supply of
air cut off from the combustion chamber the degree of heat is much higher than in
furnaces having angular combustion chambers, bridge-walls, and ash-pits, which
result can only be attributable to the reverberatory. effect, attained by my
construction, and is due mainly to the form of the combustion chamber.
:
With the supply of air cut off from the combustion chamber when firing up the
volume of smoke is not materially decreased, and the flame is dark and heavy, and
advances only slightly beyond the bridge-wall, but with a supply of air through
the hollow bars to the combustion chamber the smoke instantly disappears, and a
continuous flame darts forward to the rear end of the furnace and some two feet
or more into the flues of the boiler, and little or no smoke appears at the stack.
These results are due partly to supplying and the manner of supplying air to
the products in the combustion chamber, but as a whole to the reverberatory
effect of the furnace combined with the air supply, the reverberatory effect of the
furnace serving to raise the temperature of the products of combustion to cause
them to fully ignite when in contact with the air, the ignition of these products in
the combustion chamber establishing a uniforin degree of heat over the entire
surface of the boiler projecting into the fire and combustion chambers!
The outer ends of the air chambers N may be provided with a net-work of brick
or iron to divide the current, but this is not material to my invention, nor is the
form of conveyor shown, for any other form may be substituted, or a scraper may
be employed to the same end.
By reference to Fig. 4 it will be seen that the side linings of the fire-chamber
and the supplemental bridge-wall are in effect a supplemental furnace protecting
and adapted to be removed from the furnace proper when burnt out; and be
replaced with new material without disturbing the same, hence the durability of
the furnace proper is very materially increased.
As will be observed the linings and supplemental bridge-wall very materially
diminish the area of the grate, and with it the fire surface of the furnace, but
practical use has demonstrated that with the above described construction less
grate Surface and a correspondingly diminished amount of fuel is required for
successful operation than in furnaces constructed in the ordinary way.
The invention is not limited to the use of a single conveyor and its attachments
and connections in a furnace; for the conveyor may be used in any numbers
required by any particular construction of furnace, as for example a furnace having
three independent or continuous combustion chambers as shown in Figs. 6 and 7.
Having now particularly described and ascertained the nature of the said
invention as communicated to me, and in what manner the same is to be performed,
I declare that what I claim is:-
1st The combination in a furnace of a bridge-wall and a combustion chamber
arranged in the rear of and extending in a plane below the top of said.bridge-wall,
said combustion chamber having the masonry of its longitudinal sides and bottom
concaved or inclined to a uniform depth so that the longitudinal line thereof shall.
be in a horizontal plane, and provided with means of access for the removal of
accumulations without interrupting the operation of the furnace, substantially as
described.
2nd-The combination in a furnace of a. bridge-wall, and a combustion chamber
arranged in the rear of and extending in a plane below the top of said bridge-wall,
:

page_text: said combustion chamber having the masonry of both sides and ends and its
bottom concaved or inclined to a uniform depth, so that the longitudinal lines of
the sides and bottom shall be in a horizontal plane, and provided. with means of
access for the removal of accumulations without interrupting the operation of the
furnace, substantially as described.
3rd The combination in a furnace of a bridge-wall, a combustion chamber in
the rear thereof, and a conveyor arranged in the masonry forming the bottom of
said combustion chamber, substantially as described.
-
4th The combination in a furnace of a combustion chamber arranged in the
rear of the fire-chamber, and a.conveyor arranged within and in a plane below
the bottom of said combustion chamber, and adapted to remove the accumulations
therein, substantially as described.
5th The combination of the combustion chamber, the bottom of which is a
contiguous part of the masonry of the side walls of the boiler setting, and is
grooved to receive accumulations with means for removing such accumulations,
substantially as described.
6th The combination with the combustion chamber of the series of pivoted and.
hollow bars forming air inlets, and means for operating said bars, substantially as
described.
7th The combination with the combustion chamber, and with the receptacle for
the accumulations of the intermediate swinging bars, and means for operating the
same, substantially as described.
8th The combination in a furnace of a combustion chamber constructed in the
masonry thereof and arranged in the rear of the fire chamber, the accumulation
receptacle in the bottom of the combustion chamber, an air chamber surrounding
the receptacle and air inlets opening into said air and combustion chambers,
substantially as described.
9th The combination with a furnace of a bridge-wall, the front face of which'
is convex and its extremities joining the sides of the furnace concaved at i,
substantially as and for the purpose described.
Dated this 10th day of March 1884
WP. THOMPSON,