Improvements in Furnaces.
Year: 1898

page_text: - Date of Application, 15th Mar., 1898-Accepted, 7th May, 1898
COMPLETE SPECIFICATION:
Improvements in Furnaces.
A, communication to me from THEODORE AYRAULT DODGE, of Boston, Massachusetts,
in the United States of America, Manufacturer.
I, EDMUND EDWARDS, of the Firm of Edwards and Co., Patent Agents and
Engineers, of 65 and 66, Chancery Lane, London, 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 :-
:
The object of my invention is to provide a means for burning coal without
making smoke, and so as to utilize the gases that are lost when the ordinary
furnaces are used. My invention is applicable to all kinds of horizontal boilers, as
well as locomotive, marine and upright boilers, and in fact to all furnaces, and it
is designed by me to make use of the highest rate of combustion that can be
obtained. The objections arising from the use of cheap coal, such as smoke and
clinkers, I also design to overcome, and to increase the efficiency of the boiler, by
procuring the highest evaporation.
I accomplish the objects mentioned, by the use of tiles, placed a suitable distances
above the grate bars, having holes preferably placed at different angles through
which atmospheric air is forced, or blown upon the coal; and also by the use of
combustion chambers, through which the heated air and smoke pass, so placed
that a large part of the heat which they contain is utilized. The greater part of
the air required for the combustion of the coal is usually supplied to the tiles, and
forced down into the coal, and a lesser amount of air is supplied under the grate.
Different coal may require different proportions of air to be supplied from above
and below.
I design to build my furnace for stationary boilers of brick, as generally used in
the setting of boilers, and to employ in addition perforated tiles, of fire brick
shapes, and to place the tiles in a suitable position to conduct and mingle the
atmospheric air, under pressure with the coal and the gases.
I design to use grates of the usual construction, which I vary according to the
fuel burned; and I use tiles made of benezette, plumbago and German clay, or any
other suitable material. The tiles are made on an angle, as shown in Figure 1 of
the drawings, hereafter to be referred to, or they may be made. straight if desired.
The perforations in the tiles may be made on different angles to each other, so as
to distribute the air to all parts of the furnace. In all furnaces where it can be
readily built, I use a second combustion chamber for the purpose of retarding the
heat and supplying it to the shell' of the boiler a longer time than can be done
with the ordinary setting, thus allowing the boiler to absorb the heat instead of
passing it up the chimney. In horizontal, tubular and Heine's boilers, this second
combustion chamber is built back of the bridge wall, and in Babcock and Wilcox
boilers, it is built above the tubes, as shown in Figure 4 of the drawings.
flt. f
In the drawings, in Figure 1, I have shown a vertical longitudinal section of a
horizontal, tubular boiler, embodying my invention.

page_text: :
a is the ash-pit; b is the grate bars, as in ordinary boilers; d is a slanting or
straight tile placed on the bridge wall e running across the furnace, and slanting
forward. The shoulder x is formed upon the bridge wall at its upper edge, and
the tiled is placed thereon, its lower edge being formed at such an angle that the
tile is inclined forwardly at a suitable angle over the fire for the purpose of
enabling the currents of air to be forced through its openings at different angles
upon the fire.
In order to secure the tile in place, a flanged plate m is placed both upon the
top of the bridge wall, and tile, and the flange upon, the plate, catches in a
corresponding groove in the top edge of the tile so as to secure it in position.
Upon the top of this plate, if there is room, may be built a portion of the bridge
wall, so as to anchor the plate securely in position and out of the direct effects of
the heat. The tiles are formed of sufficient thickness to enable the perforations
through it to direct the air in the desired direction.. (Figure 2) is a similar tile
placed on each side of the space above the fire box, similarly to the tile d, and it
extends from the bridge wall e to the front of the furnace. These tiles on the
sides of the fire chamber are supported upon shoulders al in the side walls, and are
anchored in place by angular flanged plates m¹, or by other suitable means. These
tiles are placed a suitable distance above the grate bars, and are perforated with
'holes from one-fourth to one-half an inch in diameter. These holes are preferably
placed at different angles to each other, as shown in Figure 1. Atmospheric air is
supplied to the tiles d and f from a blower, placed either at the back, front, or
side, of the boiler or furnace, or in any other suitable way. This air is taken from
over the boiler, or from any other suitable placo,, and is drawn thence down and
passes through the blower, then forced back over the boiler, thence to the small
conducting pipe n, to the chamber o, and distributed to the tiles d and f through
which it passes, as above explained, and also under the grate. Exhaust steam
from the engine if one is required to run the blower may be emptied into the pipe
from the blower. A pressure of from one to six ounces of air is used so as to force
it to all parts of the furnace. In this way, any temperaturo of fire required can be
obtained.
The second combustion, or retarding chamber g, is formed by building a long
arch 1, Figure 1, from the back of the boiler to within a suitable distance, say 12
or 14 inches of the bridge wall e. It is made of fire brick, or any suitable material:
In the ordinary-boiler furnace, it is from twenty-four to thirty inches below the
boiler. At the back end of the arch h, the wall i, is built up around the boiler.
At the top and back of the bridge wall, is the arch j, extending back from the
bridge wall e, a suitable distance, which is about thirty inches, in ordinary
furnaces. This arch is made imperforate so that no portion of the products of
combustion can pass through it, and is made to extend to a position with reference
to the front edge of the arch h, such that the products of combustion will be
forced backward against the wall i, before they can turn downward and forward to
make their escape through the opening k.
In this way,
the flame and gases are
carried back of the boiler, then they flow forward over the arch h, Figure 1, and
under the arch j, to the opening k, then down and back under the arch h, then
upward to the tubes or flues.
Figure 2 is a cross section on the line 2-2, Figure 1, showing the line of grate, also
the tiles d and f. The top of these tiles, and the space back of them are covered with
iron plates, or special tiles dowelled into them so as to hold them firmly in place,
and making a tight chamber, so that no air can get out, except through the
perforations.
Figure 3 is a cross section on line 3-3, Figure 1.
Figure 4 is a vertical longitudinal section of a Babcock and Wilcox boiler,
embodying my invention. The fire box is constructed the same as in the case of a
horizontal boiler, as shown in Figures 1 and 2. The combustion or retarding
chamber g, is built above the line of tubes, as shown in Figure 4.

page_text: The gases passing upward between the tubes instead of immediately turning
down as in ordinary boilers, are carried up and around the boiler a, then back, and
then forward and downward, as usual.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1st In a furnace, the bridge wall, provided with a shoulder, and the side walls
of the furnace provided with corresponding shoulders, the tiles provided with a
series of perforations for the escape of the air, combined with the air chambers back
of the tiles, substantially as shown.
2nd: In a furnace, the bridge wall, the imperforate arch extending backwardly
therefrom, and the wall i, combined with the chamber g and the arch / extending
forwardly from the wall i, beyond the rear edge of the arch j, whereby the
products of combustion are forced rearwardly the full length of the chamber,
before they turn downwardly and forward towards the openings k, substantially as
described.
EDWARDS AND Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.
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