An Improved Furnace.
Year: 1893

page_text: Date of Application, 10th June, 1893
Complete Specification Left, 12th Mar., 1894-Accepted, 9th June, 1894
PROVISIONAL SPECIFICATION.
An Improved Furnace.
I, ROBERT DEMPSTER, of No. 411 Court Avenue, Des Moines, Iowa, U.S.A.,
Gentleman, do hereby declare the nature of this invention to be as follows:-
This my invention has reference to an improved furnace, but more especially
to boiler furnaces; the object of the invention being to provide means whereby
fuel is economised and greater efficiency attained.
By this my invention I construct a hollow bridge wall in the rear of the combustion
chamber and said wall has perforations in its forward face. A second hollow
bridge-wall is constructed at the rear of the first, and has perforations in the top
thereof. A perforated wall inclines downwardly from the forward bridge wall to
the rear one. A superheating coil is arranged at the back of the rear or second
named bridge wall and communicates with the outside atmosphere. Air passages
are made in the side walls of the furnace and lead from the superheating coil to
the hollow interior of the forward bridge wall. Perforations are made in the side
walls to lead from the air passages aforesaid to the space between the bridge walls
above the inclined wall; and air passages lead from the hollow interior of the
forward bridge wall to the hollow interior of the rear bridge wall, and perforations
are made in said passages which lead to the space beneath the inclined wall.
Dated this 10th day of June 1893.
W. H. MUNNS,
Agent for Applicant.
An Improved Furnace.
I ROBERT DEMPSTER of 411 Court Avenue, Des Moines Iowa, U.S.A.
Gentleman 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 simple, cheap and durable means
whereby pure air in a superheated state may be made to commingle with the
products of combustion in a more thorough manner than has heretofore been
accomplished and at the proper point within the furnace to thereby consume all of
the black smoke, soot and volatile gases.
With this end in view my invention consists in certain details in the construction,
arrangement & combination of bridge walls, superheating pipes, air chambers &c.
as hereinafter set forth, pointed out in my claim and illustrated in the accompanying
drawings in which :-
Fig. 1 is a vertical longitudinal sectional view of the complete furnace. Fig. 2
is a transverse sectional view of the same, through the line - of Fig. 1, looking
rearwardly. Fig. 3 is a vertical sectional view of the same through the line y-y
of Fig. 1, obtained by looking forwardly.
Fig. 4 is a vertical longitudinal sectional view of one of the side walls.
Fig. 5 is a horizontal sectional view through the line of Fig. 6.
Fig. 6 is a vertical longitudinal sectional view through the furnace in which
several modifications over Fig. 1 are shown.

page_text: Referring to the accompanying drawings the reference letter A is used to
designate the side walls of the furnace, A' the end walls and A' the top, all of
which are preferably constructed of brick in the usual manner.
A is a grate in the combustion chamber of the furnace.
B designates a bridge wall in the rear of the grate over which all of the products
of combustion must pass before reaching the flue.
B' is a second bridge wall located some distance in the rear of the first having
an arched opening B³ through which the products of combustion must pass.
C designates an inclined perforated wall extending from the top of the front
bridge wall B to the rear bridge wall B2. This wall is supported upon the
perforated upright walls C2 which rest upon a suitable base C³. In the rear of
this second bridge wall B2 is a superheating chamber D within which is coiled a
superheating pipe D' which communicates with the outside atmosphere through the
furnace walls.
D³ designates air chambers one of which is located in each side wall of the
furnace, said air chamber being in direct communication with the superheating
coils D, and extending forwardly to a point opposite the forward bridge wall, the
inner sides of said chambers are perforated at D' to discharge the heated air into
the space between the front and back bridge walls. Do designates like air chambers
in the forward portion of the side walls extending along that portion of the side
walls in contact with the combustion chamber, perforations D are made to provide
communication between said air chambers D' and the combustion chamber.
F designates an air chamber formed in the top portion of the forward bridge
wall extending from one side wall to the other and communicating with the air
chambers D³ in the side walls.
F designates perforations in the front face of the bridge wall.
F3 Fig. 5 is an opening in the bottom of the air chamber F leading to a like
chamber F1 beneath it.
H designates an air chamber in the interior of the rear bridge wall. This
chamber is made to communicate with the chamber F4 in the forward bridge wall
by the air passages H* formed in the side walls and also the air passage H³ leading
from the central portion of the air chamber F to the chamber H. This latter
air passage H³ is allowed to discharge part of its contents upwardly through
It will thus be
perforations in its top into the space between the bridge walls.
seen that by this arrangement of pipes, air chambers &c. pure atmospheric air
is drawn from the outside of the furnace through pipes D2 coiled within the
space D, and conducted from thence to an air chamber in the forward bridge wall
in close proximity to the combustion chamber, where its heat is increased. A
certain quantity of air is also admitted into the combustion chamber through
the perforations in the side walls. The superheated air is then discharged
into a long narrow passage through which the products of combustion must pass.
In practical use the discharge of superheated air from four directions to one
common centre, that is from both side walls, from the front face of the bridge wall,
and from the top of said bridge wall to a point directly above the grate where the
combustion takes place, will produce a diversity of currents of superheated air
which retains the products of combustion directly above the hottest portion of the
fire upon the grate and supplies the proper amount of air thereto at the point to
produce the best results in the consuming of smoke, soot, &c. and the function of
the rear bridge wall and the inclined wall is to prevent the products of combustion
from passing to the flue before they have been subjected to the requisite amount of
heat & commingled with sufficient air, this they accomplish in the following
manner: It will be obvious that the rear arched bridge wall will prevent the
products of combustion from passing directly to the flue along the bottom of the
boiler or radiating drum, and compel the same to pass in close proximity to
the inclined wall. As the heat is increased upon the grate it will be obvious that
by reason of the increased draft the products of combustion would be forced over
the forward bridge wall prematurely; to counterbalance this tendency the said

page_text: inclined wall is provided and as the fire upon the grate becomes hotter the air-
within the hollow interior of the forward bridge wall is heated to a greater degree
and by means of its expansion a current of air is forced upwardly through the
inclined wall, of sufficient strength to check the passage of the products of com--
bustion at all times and as the force of this current of air is proportionate to the
amount of heat within the combustion chamber the exact amount of air is supplied
to the fire at all times.
J designates a boiler extending longitudinally of the furnace from the front to a
point near the rear end thereof.
J designates tubes extending longitudinally of the boiler from its rear end to
the flue J at the forward end of the furnace, through which the products of
combustion must pass.
In the modification shown in Figs. 5 and 6 all of the air passages, superheating
tubes &c. are built of brick and the second or rear bridge wall is shown to extend
above the place where the inclined wall C joins the wall B2 which is provided with
perforations to allow the superheated air to be discharged into the products of
combustion passing thereover in different directions as required to produce a
diversity of currents and thoroughly commingle the superheated air with the
products of combustion.
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 :-
The hereindescribed furnace all substantially as and for the purposes hereinbefore-
set forth and illustrated in the drawings hereunto annexed.
Dated this Tenth day of March One thousand eight hundred and ninety-four..