IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES FOR THE COMBUSTION OF COAL AND SIMILAR FUEL
Year: 1875

page_text: LETTERS PATENT to Dwight Foster Cameron, of Chicago, Illinois,
United States of America, now of No. 8, Southampton Buildings,
London, for the Invention of "IMPROVEMENTS IN STEAM BOILER AND
OTHER FURNACES FOR THE COMBUSTION OF COAL AND SIMILAR FUEL."-A
communication from abroad by Horatio M. Smith, Moses W. Lester,
and Franklin Lester, all of Chicago, Illinois, United States of
America
PROVISIONAL SPECIFICATION left by the said Dwight Foster Cameron
at the Office of the Commissioners of Patents, with his Petition,
on the 27th November 1875.
I, DWIGHT FOSTER CAMERON, of Chicago, Illinois, United States of
America, now of No. 8, Southampton Buildings, London, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN STEAM
BOILER AND OTHER FURNACES FOR THE COMBUSTION OF COAL AND SIMILAR FUEL,"
a communication, to be as follows:-
It is well known that bituminous coals are rich in combustible
matters, which volatilize at a comparatively low temperature, and that

page_text: in the ordinary modes of combustion these volatile constituents become
mostly waste products of combustion, which pass out of the furnace in
the form of smoke and invisible carbonic compounds. It is also well
understood that sufficient air cannot pass through the grate of a furnace
to produce complete combustion of the necessary quantity of coal resting
thereon, and though an accelerated draft intensifies combustion and pro-
portionately elevates the temperature, yet the fires cannot be urged
beyond a certain point, except at an expense of fuel greater in proportion
than the increase of temperature obtained; therefore the problem has
been to burn the combustible gases after they have been distilled and
have escaped from the fuel upon the grate. Active combustion cannot
occur below a certain temperature, and from the moment of their
liberation these gases begin to lose heat, and the admission of cold air
above the grate may and generally does cool them below the temperature
of ignition.
The object of this Invention is the complete combustion of these gases
by subjecting them to the intense heat of a blast without accelerating
the draft through the grate. It is evident that this effect should be
produced as near to the grate as possible.
The said Invention comprises,-
•
First. A narrow throat at the rear end of the grate, through which
these waste gases, mixed with fresh air, may be compelled to pass at an
accelerated velocity, and in contact with a mass of intensely burning
fuel, whereby the temperature is so raised that combustion is made
complete.
Second. A dead plate continuation of the grate surface to hold the
coke or coal which is used to block up said archway.
Third. A splayed or inclined bridge wall behind said arch and dead
plate to permit the flame to be partly diffused before impinging upon
the boiler.
In this furnace one part of the same fire is maintained at a much
higher temperature than the remainder, and the waste gases are com
pelled to pass said hot part before they have lost temperature or formed
incombustible oxides.
In applying this Invention to a steam boiler I build a central ver-
tical division wall extending from the ground up to the boiler, and from

page_text: the front back to an inclined bridge wall. The bridge wall is made
inclined, so that the draft of flame will not be caused to impinge too
abruptly upon the boiler and burn the plates thereof at a certain point.
Within each of the two chambers formed by the exterior walls the
boiler and the central wall are placed partitions, preferably in the form
of arches at a point just over or very near to the rear end of the grate,
and in front of the inclined bridge wall; these arches descend nearly to
the grate, so that a narrow throat is formed, which may be readily
blocked up with the fuel, and which will be so narrow that no gases can
pass through without being beated to the required degree to ensure
combustion if a sufficient quantity of air should be present. An air vent
is placed at this arch, debouching either downward at the crown of the
arch or to the side or front over the arch to ensure a proper supply
of air.
In front of the aforesaid arches or partitions and above the grate, but
nearly level therewith, is an archway or passage forming a communi-
cation between the said chambers. The doors are provided with
adjustable draft openings, and similar openings furnish an air supply by
suitable conduits, which deliver it into the said chambers at or near the
rear of the furnace, and into the arched passage.
It is not desirable that the coal or other fuel pushed under the arch
to block up the same should rest against the bridge wall, I there-
fore extend the dead plate backward, level with the grate sufficiently
far to form a base for the pile of fuel, and from the rear end of this
dead plate the bridge wall rises with an inclination backward, which
permits the flame to become somewhat diffused before impinging upon
the boiler.
The top of both of the aforesaid chambers is formed by the boiler, so that
all of the heat generated within the chambers acts upon the boiler. A
single chamber provided with a closely descending arch may be suc-
cessfully used, but I prefer two, as above described.
In furnaces which have but one door the central vertical division wall
may be brought to the front, or to within a short distance of it, so that
the gases may pass from the coking to the combustion chamber around
the front edge of the wall.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Dwight Foster Cameron in the Great Seal Patent
Office on the 18th May 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DWIGHT
FOSTER CAMERON, of Chicago, Illinois, United States of America, now
of No. 8, Southampton Buildings, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of November, in
the year of our Lord One thousand eight hundred and seventy-five,
in the thirty-ninth year of Her reign, did, for Herself, Her heirs
and successors, give and grant unto me, the said Dwight Foster
Cameron, Her special licence, that I, the said Dwight Foster Cameron,
my executors, administrators, and assigns, or such others as I, the said
Dwight Foster Cameron, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Ohannel Islands, and Isle
of Man, an Invention for "IMPROVEMENTS IN STEAM BOILER AND OTHER
FURNACES FOR THE COMBUSTION OF COAL AND SIMILAR FUEL," a communication
to me from abroad by Horatio M. Smith, Moses W. Lester, and
Franklin Lester, all of Chicago, Illinois, United States of America,
upon the condition (amongst others) that I, the said Dwight Foster
Cameron, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Dwight Foster Cameron, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the accompanying
Drawing forming a part of this Specification:-
It is well known that bituminous coal is rich in combustible matters,

page_text: which volatilize at a comparatively low temperature, and that in the
ordinary modes of combustion these volatile constituents become mostly
waste products of combustion, which pass out of the furnace in the
form of smoke and invisible carbonic compounds. It is also well under-
stood that sufficient air cannot pass through the grate of a furnace to
effect the complete combustion of the necessary quantity of coal resting
thereon, and though an accelerated draft intensifies combustion and pro-
portionately elevates the temperature, yet the fire cannot be urged
beyond a certain point, except at an expense of fuel very great in pro-
portion to the increase of temperature obtained; therefore the problem
has been how to burn the combustible gases after they have been dis-
tilled and have escaped from the fuel upon the grate. Active combustion
cannot occur below a certain temperature, and from the moment of their
liberation these gases begin to lose heat, and the admission of cold air
above the grate may and generally does cool them below the temperature
of ignition.

page_text: Figure 1 is a front elevation of a furnace constructed according to this
Invention; Figure 2 is a vertical transverse section of the said furnace;
Figure 3 is a vertical longitudinal section of the same.
Like letters indicate the same parts throughout the Drawing.
A represents a steam boiler; B, B, are the exterior walls of the
furnace; C is a central vertical division wall extending from the ground
up to the boiler, and from the front back to the inclined bridge wall D.
This bridge wall D is made in this form in order that the draft of
flame will not be caused to impinge too abruptly upon the boiler, and
burn the plates thereof at any point. Within each of the two chambers
E, E', formed by the exterior walls the boiler and the central wall are
placed partitions, preferably in the form of arches F, at a point just
over or very near to the rear end of the grate G and in front of the
inclined bridge wall D; these arches descend nearly to the grate G, so
that a narrow throat is formed, which may be readily blocked up with
the fuel, and which will be so narrow that no gases can pass through
without being heated to the required degree to insure combustion if a
sufficient quantity of air should be present. An air vent fis placed at
this arch, debouching either downward at the crown of the arch or to
the side or front over the arch to ensure a proper supply of air. I prefer
that the parts F should have the form of arches, but it is not essential
that they should have this form, as will be readily understood; nor is it
essential that they should be placed in the precise position shewn, as it
may often be advisable to arrange them farther to the rear,
and even
beyond the back of the grate.
In front of the arches or partitions F above the grate, and nearly level
therewith, is an archway or passage H forming a communication between
the chambers E, E. The doors J are provided with adjustable draft
openings b'. I also provide similar openings i to furnish air by
suitable conduits & into the chambers E, E¹, at or near the rear of the
furnace into the arched passage H from above, as indicated by the
arrows, Figure 2.
It is not desirable that the coal or other fucl pushed under the arch E

page_text: extend the dead plate t level with the grate, sufficiently far backward to
form a base for the pile of fuel which chokes the said arch, and from the
rear end of said dead plate the bridge wall D rises with an inclination back-
ward, which permits the flame to be somewhat diffused before impinging
upon the boiler, therefore there is no danger of burning the plates of
the latter in the vicinity of the bridge wall.
In using this improved furnace I first charge both chambers with coal
and dam up the fuel, so that it shall be "coked" at the arches F, or if
preferred coke fires may be built in each chamber, or a coke fire may
be built upon one side and a coal fire upon the other side of the
furnace.
When the fire is fairly started in the latter case I dam up the coal
under the arch F by pushing it so far back that there shall be very little
or no outward draft over the bridge wall. Sometimes it may be found
desirable to close this outlet, which may be done by the damper K.
The draft is thus brought around through the passage H into the other
chamber containing a coke fire. Air from the apertures at the rear and
at the passage H mingles with the gases evolved from the coal, both at
the time of their generation and as they pass through the passage H,
and the said gases will therefore be in a condition to burn upon
entering the chamber containing the coke fire. The flame is carried
by the draft in the latter chamber up over the bridge wall in the usual
manner.
The two chambers are of equal capacity, and when the coal in the
closed chamber has become reduced to coke a charge of coal is placed in
the outer chamber in like manner, and dammed up at the throat under
the arch F, making it in turn a coking chamber, and the draft is
reversed into the other chamber; or if desired the coke may be dumped
by the grate, and transferred from one chamber to the other through the
ash-pit.
The top of each of the said chambers is formed by the boiler, so
that all of the heat generated within the chambers acts upon the said
boiler. A single chamber, provided with an arch F, may be successfully
used, but I prefer two chambers, as above described, for the purpose of
my Invention.
In furnaces which have but one door the central vertical division
wall C may be brought to or nearly to the front of the furnace, so that tho

page_text: gases may pass from the coking to the combustion chamber around the
front edge of the wall O.
In many instances, where the draft is good and the grate and steam
heating surfaces are large, it will not be necessary to bank the coke
under the throat on either side, as the small space left between the
arch F and the grate surface through which the mingled smoke and air
must pass, will force them so close to the incandescent coke or coal as
to insure combustion in the chamber where the gases are generated.
Having thus fully described the said Invention as communicated to
me by my foreign correspondents, and the manner of performing the 1
I wish it understood that I claim,—
same,
First. In a furnace the combination with the rear grate surface and
its supporting wall of an arch or partition, constructed and arranged to
form a throat or chamber at the juncture of the said grate and wall, as
above set forth and for the purpose specified.
Second. In a furnace the combination with the rear grate surface and
its supporting wall and the said arch or partition at the juncture of
the grate and wall of air supply pipes or openings, debouching at the
crown or in front of the said arch or partition, as above set forth and for
the purpose specified.
Third. In a furnace the combination of the grate, the arch, or par-
tition, the dead plate, and the bridge wall, in the manner set forth and
for the purpose specified.
In witness whereof, I, the said Dwight Foster Cameron, have here-
unto set my hand and seal, this Fourth day of May, in the
C
114
Tand One thousand eight hundred and seventy.
the purpose specified.
Third. In a furnace the combination of the grate, the arch, or par-
tition, the dead plate, and the bridge wall, in the manner set forth and
for the purpose specified.
In witness whereof, I, the said Dwight Foster Cameron, have here-
unto set my hand and seal, this Fourth day of May, in the 1
year of our Lord One thousand eight hundred and seventy
DWIGHT FOSTER CAMERON. (L.S.)
Witness,
GEORGE COOK CAMPBELL.