Improvement in Furnaces.
Year: 1891

page_text: Date of Application, 10th Nov., 1891-Accepted, 6th Feb., 1892
COMPLETE SPECIFICATION.
Improvement in Furnaces.
I, Edward KERR, Hammerman, residing in Evaline Street near Liberty
Avenue, Pittsburgh, in the County of Allegheny, State of Pennsylvania, 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 :-
The invention described herein relates to certain improvements in furnaces for
melting metal and other metallurgical processes. Many attempts have heretofore
been made to effect the melting of metals in furnaces of the cupola type, by means
of a gaseous fuel, as natural gas, artificial gas or the gases or products of com-
bustion in a chamber adjacent to the melting chamber. In these furnaces the gas
is introduced into the crucible portion of the furnace and passes thence upward
through the furnace, many different forms of devices being employed to support
the charge until melted. These attempts have been unsuccessful as the metal
becomes soft and settles down into a compact mass, and prevents the passage of the
heat and products of combustion, thereby effectually stopping any further melting
of the metal. The object of the invention herein is to provide for the application
of heat on top of the charge and causing the heat and products of combustion to
pass down through the charge into the crucible, and thence into the stack. The
invention consists in the construction and arrangement, as hereinafter more fully
described and claimed.
In the accompanying drawings forming a part of this Specification,
Fig. 1 is a sectional clevation of a cupola furnace constructed in accordance with
my invention;
Fig. 2 is a similar view of a modified form of furnace ;
Fig. 3 is a sectional elevation of a furnace embodying my invention;
Fig. 4 is a similar view, the plane of section being indicated by the line a, a,
Fig. 3;
Fig. 5 is a sectional plan view of the furnace ; and,
Fig. 6 is a view similar to Fig. 3, showing a modification of the furnace.
The furnace 1 shown in Fig. 1 is constructed as regards its external shape
similarly to the ordinary cupola furnace. Within the furnace .at a suitable distance
from the bottom of the furnace is formed an inward projecting shelf or abutment 2,
separating the crucible 3 from the upper portion of the furnace and forming a
contracted throat for the passage of the molten metal. The metal to be melted
is charged into the furnace through the opening 4, in the upper portion or melting
chamber 5 of the furnace, and is supported until melted by the annular shelf or
abutment 2. On the top of the cupola is formed a funnel shaped nozzle
and
centrally within said nozzle is arranged the gas supply pipe 7. The end of this
pipe 7 is so arranged within the nozzle that the gas, entering through said pipe,
and the air, either drawn or forced through the nozzle, will be so thoroughly
commingled that combustion will occur just below the point of entrance of the
nozzle within the melting chamber. The heat and products of combustion pass
down through the charge resting upon the shelf or abutment 2 then through the
crucible 3, and thence by the ports 8 and pipe 9 into the stack 10. As shown in
Fig. 1 the ports 8 correspond or approximately so with the openings for the tuyeres
of the ordinary cupola, and are connected to the pipe 9 surrounding the furnace,
said pipe having a branch leading to the stack. Any number of ports 8 may be
employed and if desired may have an independent connection to the stack.
The construction shown in Fig. 2 is similar as regards all essential particulars
to the construction shown in Fig. 1, except that only one port 8 for the escape of

page_text: the products of combustion is employed, and that said port is connected to one end
of a heating chamber 11, which is connected at its opposite end to the stack. This
form of furnace, i.e. that shown in Fig. 2 is somewhat smaller as regards the
dimensions of the melting chamber and crucible, and is more especially adapted
for melting brass, and in such metallurgical operations as the reduction of metals
from their ores. If desired two or more nozzles each provided with a gas pipe
may be employed as indicated in dotted lines in Fig. 2.
By properly proportioning the length of the melting chamber, and so adjusting
the gas supply pipe that combustion will at least commence at or near the point of
entrance of the gas and air into said chamber, the melting of the charge will
commence on top thereof and gradually progress, the hottest point being somewhat
above the throat of the furnace. As the metal above is softened by the heat it
will gradually settle down towards the throat, being subjected to a constantly
increasing heat, and before it can coalesce it will be entirely melted and flow down
through the part of the charge below and gradually heat and eat it away, thus
preserving a clear passage for itself into the crucible. The heat and products of
combustion will maintain the molten metal in the crucible in a hot condition,
and further as the products of combustion are wholly non-oxidizing in their
character the molten metal in the crucible will be entirely protected from any
oxidation. The heating chamber 11 affords opportunity for raising the metal to a
high temperature before charging it into the melting chamber, thereby facilitating
the melting operation.
The construction shown in Figs. 1 and 2 is more especially designed for the
utilization of natural gas, or artificial gas generated at a distance from the melting
furnace. While such gases may be used in the form of furnace shown in Figs. 3
to 6, such construction is especially designed for use where the generator is in
close proximity to the melting chamber. In this form of apparatus the melting
chamber 5 is supported upon platform 12 supported on suitable posts or pillars, a
sufficient distance above the floor level, to permit of the crucible 3 being raised a
sufficient height to allow of the tapping off of the molten metal therefrom. As
shown in Figs. 3, 4 and 6, the crucible is arranged immediately below the melting
chamber and is connected thereto by a throat or passage 13.
One, two or more fire chambers 14 are arranged outside of the melting chamber 5,
and are connected thereto by passages 15 entering the melting chamber at or near
the top thereof. As shown in Figs. 3, 4 and 5, these fire chambers are provided
with grate bars, for supporting the solid fuel employed. The heat and products of
combustion of the fuel flow through the passages 15 into the melting chamber and
are drawn down through the throat 13 into the crucible, from which they pass by
the flues or ports 8 and conduits 9 into the stack 10.
The charge to be operated on is placed upon the annular hearth or shelf 2 of
the melting chamber around the throat 13 and the heat and products of combustion
are caused by the draft of the stack to impinge upon the charge and melting the
metal pass thence through the throat with the molten metal into crucible, in which
the metal is maintained in a molten condition by the heat and products of combus-
tion as they pass through the crucible to the stack.
The melting chamber 5 is provided with one or more doors 4 through which the
charge is placed therein, and the fire chambers 14 are provided with fuel charging
doors 16. It is preferred to form a slight ridge 17 around the throat 13 except
at one point where a gutter 18 is formed so that the metal lying on the shelf 2
will as it is melted, flow along the annular ditch formed back of the ridge 17 to
the gutter 18, and thence into and through the throat, the bottom of the gutter
having a downward pitch or inclination towards the throat. This construction
permits of the molten metal collecting in a larger body before flowing into the
crucible, thereby preventing any material oxidation of the metal.
In order to provide for injecting one or more streams of air into the flame and
products of combustion as they pass through the melting chamber, one or more
nozzles 19 are arranged in the roof of the melting chamber. These nozzles are

page_text: arranged at such an angle as to direct the jets of air towards the axial line of the
throat at or about the upper end thereof, as shown in Fig. 3. In order to heat
the air before it enters the melting chamber, it is preferred to form a passage 20
around the throat 13 near its upper end, and connect said passage with the nozzles 19
and an air forcing apparatus.
If preferred the chambers 14 may be constructed in the form of gas producers
of any construction as shown in Fig. 6. When this construction is employed,
charging chutes 21 are arranged in the roofs of the chambers and air pipes 22
enter below the grates thereof. It is preferred to form the ports or flues 8 with an
upward inclination as they leave the crucible in order to prevent any metal from
entering the flues leading to the stack.
When it is desired to melt large heavy masses of metal the floor 12 is preferably
arranged at the ground level, the crucible being arranged in a pit.
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. A furnace having in combination a melting chamber, a crucible arranged
below the melting chamber, and connected to the stack, and a burner arranged to
introduce the gas into the melting chamber at a point above the charge, substan-
tially as set forth.
2. A furnace having in combination a melting chamber, a crucible arranged
below the melting chamber and connected to the stack, an annular abutment or
shelf interposed between said chamber and crucible, and a burner arranged to
introduce gas into the melting chamber at a point above the charge, substantially
as set forth.
3. A furnace having in combination a melting chamber, a crucible arranged
below the melting chamber, and connected to the stack and one or more fire
chambers connected to the melting chamber at a point or points above the hearth
of the melting chamber, substantially as set forth.
4. A furnace having in combination a melting chamber, a crucible arranged
below the melting chamber and connected to the stack, one or more fire chambers
connected to the melting chamber at one or more points above the hearth of the
melting chamber, and one or more nozzles arranged to direct air towards the
connection between melting chamber and the crucible, substantially as set forth.
Dated. Pittsburgh, U.S.A., this
21st day of
ד
an aSTEZ
BYLINY
EDWARD KERR.
Witnesses-
DARWIN S. WOLCOTT.
J. SNOWDEN BELL.