IMPROVEMENTS IN MELTING FURNACES
Year: 1872

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN MELTING FURNACES." -A communication from
abroad by George H. Sellers, of the City and County of Phila-
delphia, in the State of Pennsylvania, United States
America.
of
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 8th January 1872.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
5 of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN MELTING FURNACES," a communication to
me from abroad by George H. Sellers; of the City and County of
Philadelphia, in the State of Pennsylvania, United States of America,
to be as follows :—

page_text: intensely hot flame sweeps across and is reverberated upon the charge
of metal contained in a concave hearth or bed, the flame being in the
present state of the art usually derived from the combustion of what is
denominated gaseous fuel.
In the best practice now obtaining in the arts, the gaseous fuel con-
sists of gases from a producer and of atmospheric air supplied thereto for
their combustion, the air and the gases being respectively heated on
their way to the point at which they commingle, the point of com-
bustion, so that they reach this point at respectively high temperatures
and produce an intensified flamc.
The use of gaseous fuel has led to the further economy of utilizing the
waste products of its combustion in heating the respective currents of
incoming air and gas on their way to the furnace, and this has been
effected by the combination with the furnace of an apparatus technically
denominated a "regenerator."
This Invention contemplates the use of regenerative apparatus in
connection with the improved furnace, and its object is to intensify still
further the intense heat derived from the combustion of gascous fuel,
and this part of the Invention consists in so constructing the furnace
that there can be brought in at nearly opposite sides thereof two separate
flames which sweep across towards each other, and abut against each
other with such force as to produce an intimate commingling of the air
and gas in the one flame with the air and gas in the other flame, and by
this more thorough and intimate mixture of the air and gases a more
intense heat is obtained than can be derived from the same air and gases
if introduced in the usual way upon parallel lines, and necessarily lack-
ing the intimate mixture resulting from the improved mode of abutting
the two flames against each other.
Another feature of this Invention consists in constructing the furnace
in a circular or in an oval form, so that hoops or bands around its cir-
cumference will suffice for its main support, the arched crown expending
its thrust upon and being also supported by these hoops or bands around
the circumference instead of constructing the furnace, as heretofore, in
a square or oblong form with rectangular walls, which walls are tied
and sustained by numerous stay bolts, staves, and angle plates, which
must also sustain the thrust of the crown of the furnace resting upon the
side walls.

page_text: This improved form of furnace possesses the advantages incident to
the spherical form of the crown, which can be evenly supported in every
direction radially, whercas in the ordinary construction the crown forms
a portion of either a cylinder or of a cone, and in either case is supported
only in a transverse direction. The arched crown abuts against the
roof of the furnace on a plane below the top of the casing.
Another feature of this Invention, to the use of which the circular or
oval form of construction is specially adapted, consists in placing the
charging door next the down take" of the furnace, thus bringing
the two openings nearly together upon the outer circumference of the
hearth, in order that fresh air, if any be admitted during the operation
of charging, may be drawn directly into the down-take fluc, instead of
sweeping through the furnace and exerting a cooling or an oxydizing
influence upon the charge.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Scal Patent
Office on the 4th July 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of January, in the year
of our Lord One thousand eight hundred and seventy-two, in the
35th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or 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 Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN MELTING FURNACES," a communication to me from abroad by George

page_text: version of iron into steel, demand yet higher heat than it had hitherto
scemed practicable to derive from any fuel that can be used.
It is the object of this Invention to intensify still furthur the intense
heat derived from the combustion of gaseous fuel, and this part of the
Invention consists in so constructing the furnace that there can be
brought in at nearly opposite sides thereof two separate flames, which
sweep across towards each other, and abut against each other with such
force as to produce an intimate commingling of the air and gas in
the one flame with the air and gas in the other flame, and by this.
more thorough and intimate mixture of the air and gases a more intense
heat is obtained than can be derived from the same air and gases if
introduced in the usual way upon parallel lines, and necessarily lacking
the intimate mixture resulting from the improved mode of abutting
the two flames against each other. Another feature of this Invention.
consists in constructing the furnace in a circular or in an oval form,
so that hoops or bands around its circumference will suffice for its
main support, the arched crown expending its thrust upon and being
also supported by these hoops or bands around the circumference,
instead of co.`structing the furnace as heretofore in a square or oblong
form with rectangular walls, which walls are tied and sustained by
numerous stay bolts, staves, and angle plates, which must also sustain
the thrust of the crown of the furnace resting upon the side walls.
This improved form of furnace possesses the advantages incident to
the spherical form of the crown, which can be evenly supported in every
direction radially, whereas, in the ordinary construction the crown forms
a portion of either a cylinder or of a cone, and in either case is sup-
ported only in a transverse direction.
Another feature of this Invention, to the use of which the circular
or oval form of construction is specially adapted, consists in placing
the charging door next the "down take" of the furnace, thus bringing
the two openings nearly together upon the outer circumference of the
hearth in order that fresh air, if any be admitted during the operation
of charging, may be drawn directly into the down take flue instead of
sweeping through the furnace and exerting a cooling or an oxydizing
influence upon the charge.
And in order that my said Invention may be fully understood, I
shall now proceed more particularly to describe the same, and for that

page_text: purpose shall refer to the several Figures on the annexed Shicct of
Drawings, the same letters of reference indicating corresponding parts
in all the corresponding Figures.
Before describing the Drawings I may observe that the regenerative
apparatus or system exhibited in connection with the peculiar melting
furnace constitutes separately no part of the present Invention, nor
of the subject matter intended to be claimed herein, as it forms the
subject matter of Letters Patent granted to me on behalf of the said
William Sellers, bearing date the Sixth of January, One thousand eight
hundred and seventy-two, No. 50. It has however been found especially
available, and for that reason has been adopted in combination with the
said improved furnace.
Fig. 1 of the Drawings is a vertical transverse section (at the line
1-2 of Fig. 3) through the furnace and through the regencrative
apparatus; Fig. 2 is a longitudinal section (at the line 3-4 of Fig. 3)
through the furnace and through the regenerative apparatus; Fig. 3
is a horizontal section (at the line 5-6 of Fig. 2) through the furnace;
Fig. 4 is a vertical section (at the line 7-8 of Fig. 3); and Fig. 5 is a
front view of the furnace and regenerative apparatus showing in vertical
section the gas flue and valve of the regenerator.
Fig. 3 shows the oval exterior form of the furnace with a door I,
in that side which I designate (for convenience of reference) the front,
and in which door is provided a spy hole e through which the interior
of the furnace may be observed, and the condition of the charge noted,
so as to govern the regulation of the heat applied (see also Figs. 1 and 5).
Through this door the charge may be rabbled in the ordinary way.
The charging door K (Figs. 3 and 4) is located at the back of the
furnace, and in such proximity and relation to the chimney H that the
openings from the furnace into the chimney and from the charging door
into the furnace are brought very nearly together so that the fresh air
if any admitted while the charging door is necessarily open, will be
drawn directly into the chimney instead of passing into or through the
furnace, and cooling or oxydizing the charge of metal.
The furnace chamber A (Figs. 1, 2, 3, and 4) has by preference a
circular form, its concave hearth B of refractory material being supported
upon a conformable bottom a, a, a, (Figs. 1, 2, and 4,) of fire-brick with
an outer shell composed of the iron plates b, b, and b¹, b¹, which shell

page_text: rests upon and is supported by a series of supports c, c, c, c, c, c, arranged
upon the floor beneath it, so as to leave spaces between them, admitting
of a free circulation of air between the shell of the furnace and the floor.
A tap hole d (Fig. 1) extends through the shell, the fire-brick, and the
hearth at a proper inclination for withdrawing the charge, being of course
properly plugged up at all other stages of the operation of the furnace. A
spout D (Figs. 1 and 5) of suitable material conducts the molten metal
flowing from the hearth through the tap to a ladle or mould. The
furnace is incased in sheet iron J, J, J, (Figs. 1, 2, 3, and 5,) and this
casing is banded with stout iron hoops L, L, L, in this instance
three in number, properly secured, onc at the top, another at the bottom,
and the third one about the middle of the iron casing J, J, J, where its
circuit is not interfered with by the doors I and K and the spout D, all
of which project beyond the circumference of the casing. I do not
however deem it best to leave this casing and these bands alone to
support and sustain the entire structure and to resist the thrust of the
crown of the furnace, but prefer to supplement these bands respectively
with stay rods m, m, (Figs. 2, 3, and 5,) arranged in pairs and extending
across the furnace in the direction of its shortest axis. These stay rods
are secured in this instance at one end in the framework O (Figs. 1, 3,
and 5) of the door I and of the spout D (Fig. 5), which frameworks
are thereby kept in place, and the other ends of the stay rods are secured
in staves or bearer plates N, N, (Figs. 1, 2, 3, and 5.) The crown M
(Figs. 1 and 2) of the furnace is arched in the form of a section of a
hollow sphere, so that it abuts against and expends its thrust upon the
walls of the furnaces equally in all directions, the casing, the bands, and
the stay rods thus all contributing to resist this thrust and to sustain the
arched crown.
I
A further decided power of resistance to these thrusts I have attained
in the instance illustrated at Figs. 1, 2, and 4 in the Drawings by
inclining the roof of the furnace slightly downward from the shell to
the abutment of the arch, so that the roof receives the thrust of the
arch at every point of its circumference on a plane below the plane of
the upper supporting band of the casing. On opposite sides of the
furnace I provide two flues E and E¹, (Figs. 1, 2, and 3) through which
respectively the gases are admitted and in such relation to these gas
flues E, E¹, respectively as is proper for the purpose. I arrange two
flues F and F, (Figs. 1, 2, and 3) through which respectively the heated
air from the regenerative apparatus is brought across the mouths of the

page_text: gas flues E and E' respectively (see Figs. 2 and 3). The air flue F and
the gas flue E have a common delivery opening G (Figs. 1, 2, and 3),
and at these openings G and G' respectively the commingled air and gas
from the respective air and gas flues burst into flame, each of the two
flames thus created sweeping across the hearth B until they meet near
the door I where they commingle as one flame, which acts upon the
metal as it traverses the whole length of the hearth on its passage
towards the chimney H. As would always be the case where a current
of air and a current of gas are brought into the furnace on parallel lines,
as has been described, each of these flames is accompanied by parallel
currents of air and gas, which are not commingled, but which pass with it
into the furnace, and which would be more or less irregularly mixed and
ignited at different points in the furnace between the delivery flue and
the chimney. But in the operation of the said improved furnace two
flames coming towards each other from opposite sides of the furnace,
and each accompanied by its parallel currents of air and gas, and both
the flames and their currents abutting against each other as already
described, an intimate commixture is produced between the flames and the
currents of air and the currents of gas, so that the general combustion of
all is precipitated at that particular point, and the furnace is filled with
flame instead of with flame and unignited air and gas, necessarily resulting
in a temperature higher than could be derived from one of these single
flames under the conditions described. The products of combustion
are discharged at the rear of the furnace into the down take H, by
which they are conducted into the regenerative apparatus as shown
in Fig. 1.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
First. The combination in a furnace of two delivery flues through
which flames are introduced opposite each other so that they will abut
against each other in the furnace, herein-before described.
Secondly. The combination with a regenerative apparatus, sub-
stantially such as herein-before referred to, of a furnace into which
gaseous fuel is introduced at opposite points, substantially as and for the
Durnoses herein-before described.