Improvements in Furnaces."
Year: 1895

page_text: Date of Application, 17th Dec., 1895-Accepted, 1st Feb., 1856
COMPLETE SPECIFICATION.
Improvements in Furnaces."
I, EDWIN POWELL, Manufacturer, residing at No. 13 Alpha Terrace, in the
City of Pittsburgh, County of Allegheny, State of Pennsylvania, and United
States of America, 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 :—
My invention relates to furnaces for the evolution of heat from fuel in the
various descriptions of heating apparatus employed in manufacturing and
mechanical operations, and the generation of steam for the numerous purposes
required in the arts and trades, and its object is to provide means whereby the
thorough, economical, and smokeless consumption of fuel may be effected, in a
structure of simple and inexpensive construction and ready applicability to
existing conditions of location, service, and relation to other structures in
connection with which it may be required to be used. To this end, my invention,
generally stated, consists in the combination of a furnace or fuel chamber, a fire
bed therein which is closed to access of air below it, an air supply passage above
said firebed, a combustion chamber, an exit throat or passage connecting the fuel
chamber, at or near the fire bed thereof, with the combustion chamber, and a gas
conduit leading from the fuel chainber, above the normal plane of incandescence
therein, to a point of discharge adjacent to the discharge outlet of the exit throat
or passage. The improvement claimed is hereinafter fully set forth.
In the accompanying drawings:
Figure 1 is a vertical, longitudinal, central section through a metallurgical
furnace, illustrating an application of my invention; Fig. 2, a vertical, transverse
section through the same, at the line a, a, of Fig. 1 ;
Fig. 3, a vertical, longitudinal, central section through a glass furnace,
illustrating a modification of detail, and; Fig. 4, a vertical, transverse section
through the same, at the line y, y, of Fig. 3.
In the practice of my invention, I provide a downward draught furnace or fuel
chamber 1, having, at or near its top, a fuel supply passage or opening 2, closed
by a door 3, and having its bottom formed by a grated or perforated firebed 4, the
openings in which are provided to permit the passage of ashes into a lower closed
ash pit 5, having a tight door 6, for the removal of ashes, and provided, preferably,
with a water pan 6ª, on its bottom. The walls of the fuel chainber 1 are closed on
all sides, except as to the openings of the fuel supply passage 2 and firebed 4 above
specified, one or more air supply passages 7, formed in the front wall of the fuel
chamber, at a point above the normal level of the fuel therein, and controlled by a
door or register 8, a cleaning passage 9, in the front wall, at or near the level of
the firebed, controlled by a door 10, and gas discharge passages 11 and 12, to be
presently described. The ash pit being also tightly closed, the draught of the
fuel chamber is downward, from the air supply passage 7, through the body
of fuel.
A combustion chamber 13, in which the heat evolved from the fuel in the fuel
chamber 1 is utilized for the particular purpose for which it may be required, as,

page_text: for example, the melting or reheating of metal, glass, etc., the burning of brick,
lime, or pottery, the generation of steam, or other calorific action, is located
adjacent to the fuel chamber 1, and is separated therefrom by the rear wall 14
thereof. An exit throat or passage 11, through which the major portion of the
gaseous products of combustion evolved from the fuel in the fuel chamber 1 are
discharged into the combustion chamber 13, lends from the fuel chamber 1, at or
about the level of the highest incandescence therein, that is to say, at or closely
adjacent to the top of the firebed 4, into the combustion chamber 13. A gas
conduit 12, of which either one or more may be, employed, a plurality being
indicated in dotted lines in Fig. 2, leads from the fuel chamber 1, at a point above
the normal plane of incandescence therein, and, preferably, as shown, slightly above
the top of the normal charge of fuel in the chamber, to a point of discharge
to the combustion chamber adjacent to the discharge outlet of the exit throat or
passage 11 thereto, the object of said conduit 12 being to provide an avenue for
the passage of the smoke and partially consumed gases which may rise through the
unconsumed and cooler portions of the fuel, at and below the top of the charge,
from the upper portion of the fuel chamber to a point where they are commingled
with, and thoroughly comsumed by, the highly heated gases which pass off from
the portion of the charge of fuel, at and near the firebed, which is at the highest
degree of incandescence. The gases thus commingled burn with a flame of intense
heat in the combustion chamber, and any smoke which may be formed by incomplete
combustion of portions of the charge above that which is in a state of incandescence
is found to be completely consumed.
As shown in Fig. 1, the point of discharge of the gas conduit 12 is on one of
the boundaries of the exit throat or passage 11, between the firebed 4 and the
outlet of the passage 11 to the combustion chamber 13, so that the products of
combustion which pass through the conduit 12, meet the heated gases passing
through the exit throat 11, before the latter are discharged into the combustion
chamber, and the conduit 12 and passage 11, thus have a common outlet to said
chamber, which outlet is adjacent to the point of discharge of the conduit 12.
The same result will, however, be attained, if the conduit 12 and passage 11 deliver
the gaseous products from the fuel chamber to the combustion chamber, through
separate and contiguous outlets, the only requisites, as to the location of the point
of discharge of the conduit 12, being that it shall be such that the gaseous
products passing out of the conduit 12 must immediately mingle with the hot
gases which pass through the exit throat or passage 11, and that it shall be
sufficiently far removed from the firebed to ensure that the gaseous products
passing through the conduit 12 shall escape therefrom entirely beyond and clear of
all portions of solid fuel, and shall meet the gases which are evolved from the
incandescent portion of the fuel at a point where their traverse is unimpeded by
solid fuel or ashes.
Figs. 3 and 4 illustrate a modification in which the discharge of the products of
combustion from the exit throat or passage 11, and the gas conduit 12, respectively,
is effected through separate outlets, as above specified, the outlet of the passage 11
opening into the combustion chamber 13, as in the instance first described, and
that of the gas conduit 12, also opening into the combustion chamber, above and
closely adjacent to that of the passage 11. The partially consumed products of
combustion escaping from the outlet of the gas conduit 12, meet and mingle with
the highly heated gases discharged from the outlet of the passage 11, as both enter
the combustion chamber, and the former are, as in the instance first described,
thoroughly consumed, producing a flame of intense heat in the combustion chamber.
The combustion chamber 13 is shown as of the form employed in glass furnaces,
having "glory holes" 15, in the upper portion of its walls, but it will be obvious
that it may be of any other desired construction, without departure from my
invention.
I have found in practice that an unusually high heat is generated, and a complete

page_text: combustion effected, by a construction embodying the essential features above
described, and, while the precise action of the furnace in the evolution and.
combustion of gases may be difficult of ascertainment with absolute certainty, it
is my present understanding that this advantageous result is due to the following
facts. The smoke and partially consumed gases which are evolved from the
portion of the body of fuel above that which is in a high state of incandescence,.
are disengaged and pass off slowly, at a comparatively low temperature, owing
to the resistance of the unconsumed and cold, solid fuel above the level at which
they are generated. On the other hand, the gases evolved from the incandescent
portion of the fuel, escape freely, rapidly, and at a high temperature, through the
exit passage 11. The latter gases are, therefore, capable of carrying with them.
and consuming and utilizing the combustible products which meet and mingle with.
them at the discharge outlet of the conduit 12, thereby generating a corre--
spondingly higher degree of heat than would be attainable if the unconsumed'
products from the upper portion of the charge of fuel were led into and through
the incandescent portion thereof, and before the gases of combustion were released
therefrom, as has been proposed, prior to my present invention. The essential.
feature of difference between my improvement and the prior constructions referred
to, consists in the provision of the described means for effecting the union of the.
products of combustion of a downward draught furnace from the unconsumed and..
the incandescent portions of the charge of fuel, respectively, at a point wholly
exterior to the fuel chamber, where the tra verse of the hotter gases is unimpeded by
solid fuel, and so that combustion shall be completed at the outlet through which
the gaseous products pass into the combustion chamber, and produce a flame of
exceptionally high heat at said outlet.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The combination, substantially as set forth, of a furnace or fuel chamber, a
firebed therein which is closed to access of air from below it, an air supply passage.
above said firebed, a combustion chamber, an exit throat or passage connecting the
fuel chamber, at or near its firebed, with the combustion chamber, and a gas.
conduit leading from the fuel chamber, above the normal plane of incandescence.
therein, to a point of discharge adjacent to the discharge outlet of the exit throat.
or passage and exterior to the bed of incandescent fuel.
2. The combination, substantially as set forth, of a furnace or fuel chamber, a.
fire bed therein which is closed to access of air from below it, an air supply passage
above said firebed, a combustion chamber, and passages connecting the fuel
chamber and combustion chamber, said passages leading out of the fuel chamber
at or near the point or level of higbest incandescence, and above the normal
plane of incandescence, respectively, and discharging exterior to the bed of
incandescent fuel.
3. The combination, substantially as set forth, of a furnace or fuel chamber, a
firebed therein which is closed to access of air from below it, an air supply passage
leading into the fuel chamber above the normal upper level of the charge of fuel,
a door or register controlling said passage, a combustion chamber, an exit throat
or passage leading from the fuel chamber, at or near the level of the firebed, to
the combustion chamber, and a gas conduit leading from the fuel chamber, above
the normal upper level of the charge of fuel, and discharging, exterior to the bed
of fuel, to the combustion chamber.
4. The combination, substantially as set forth, of a furnace or fuel chamber, a
firebed therein which is closed to access of air from below it, an air supply passage
above said firebed, a combustion chamber, an exit throat or passage leading from
the fuel chamber, at or near its firebed, to the combustion chamber, and a gas
conduit leading from the fuel chamber, above the normal plane of incandescence.
therein, to the combustion chamber, and having its discharge outlet wholly exterior

page_text: to the fuel chamber and open to the products of combustion delivered through
the exit throat or passage.
5. The combination, substantially as set forth, of a furnace or fuel chamber, a
firebed therein which is closed to access of air from below it, an air supply passage
above said firebed, a combustion chamber, an exit throat or passage leading from
the fuel chamber, at or near its firebed, to the combustion chamber, and a gas
conduit leading from the fuel chamber, above the normal plane of incandescence
therein, to the combustion chamber, and having a discharge outlet therein,
independent of, and adjacent to, that of the exit throat or passage.
Dated, at Pittsburgh, Pa., U.S.A., this Eighteenth day of November
A.D. 1OUD.
Witnesses:
F. E. GAITHER.
J. SNOWDEN BELL.
EDWIN POWELL.