Improvements in Electric Furnaces.
Year: 1897

page_text: Date of Application, 1st Oct., 1897-Accepted, 6th Nov., 1897
COMPLETE SPECIFICATION.
Improvements in Electric Furnaces.
I, William SMITII HORRY, of Sault Ste Marie, County of Chippewa, State
of Michigan, U.S.A., Electrical Engineer, 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 action of a comparatively high degree of heat upon a mixture of coke and
lime results in the production of carbide of calcium. Various electric furnaces
have been devised for effecting such union of elements. Generally the furnace
consists of an iron bed-plate, which constitutes the lower electrode or pole, and
a large piece of carbon, which forms the other pole, and can be raised or lowered.
When the electric arc is struck between these poles a mixture of coke and lime is
fed in, and the resulting carbide of calcium piles up and becomes higher on the
bed-plate, the upper carbon being raised to make room for it.
After this has gone
on for some time the imperfections of such a furnace become evident. The
voltage between the poles decreases because the electrical resistance of the pile
of carbide differs from the electrical resistance of the ingredients which form it.
There is then a mass of carbide to heat up besides the heat required for generating
the arc and fusing additional material. The former is entirely wasted and
positively deleterious, because it causes the carbide to liquefy and run so as
frequently to melt the iron of the bed-plate. By reason of this waste the current
is turned off after a few hours, and the whole furnace has then to be cleaned out
and again started, and in cleaning out the furnace all the heat, instead of being
preserved, is dissipated, because the apparatus is allowed to cool down. More
recently an iron crucible has been employed instead of the bed-plate. Its use
effects a saving of time in cleaning out the furnace, but it adds to the weight to
be removed and is not an improvement in principle.
1
Objects of the present invention are to obviate the above-mentioned defects
and disadvantages, to economize heat, to adapt the furnace, to the practice of a
continuous process, to produce uniform quality in the finished product, to avoid
undue waste of material, to keep the current uniform, and to obviate the necessity
for special types of carbon-holders.
In the present invention use is made of means for producing an electric arc,
which is fixed, or, in other words, not moved in respect to the furnace, of a rotatable
receptacle for the fused materials, and of means for slowly shifting said movable
receptacle.
The nature, characteristic features and scope of the invention will be more fully
understood from the following description, taken in connection with the
accompanying drawings forming part hereof, and in which
Fig, 1 is a side elevational view, illustrating an electric furnace, embodying what
is believed to be the best means for practicing the invention.
Fig. 2 is a sectional view taken on the line 2-2, of Fig. 1, and
Fig. 3 is a detached view of one of the plates or covers shown in Figs. 1 and 2.
In a machine embodying this invention there are means for producing an are

page_text: which remains in one position and is not shifted about or drawn out.
a, a¹, indicate
such means and comprise, for the sake of illustration, carbons suitably connected
with the terminals, a³, of an electric system. As shown, the adjacent ends of these
carbons are beveled so as to form a vertical passage, as b, between them, across
which the arc is formed and through which the material to be treated is passed.
There is present in a machine embodying this invention also a movable receptacle
for the fused material. c designates such a receptacle and comprises a spool-
like structure revolubly mounted in suitable supports, standards or frames, d.
This receptacle, c, is provided with means for shifting it. The hand-wheel, e,
worm, e, and worm-wheel, e2, attached to the receptacle, c, are such means. f are
removable or detachable cover-plates, which may be provided with lips, as f',
by which the plates are made to over-lap each other, and with projections, as f*,
fitted to the flanges or heads of the receptacle, c. g are means, as bolts or clips,
by which the plates or covers, f, may be detachably applied to portions of the
periphery of the receptacle, c. h is a bottomless hopper suitably supported, for
example, by pivoting or otherwise attaching it to the standards, d, and permitting
it to hang between the flanges of and within the receptacle, c. As shown in the
drawings, this hopper is fitted with fire clay, as at h¹, and with fire brick, as at h².
Other fire-resisting material may be used, and it constitutes simple and efficient
means for insulating either or both of the electrodes, and for supporting either or
both of them without requiring the use of special clamps or holders. Moreover,
the connection between the carbon and electrical conductor may be of simple con-
struction, because it is placed away from the heated parts of the furnace.
The mode of operation of the invention may be described in connection with
the foregoing apparatus as follows;
Upon closing the circuit, the current traverses the space, b, and acts upon the
materials, as carbon and lime, of which a supply is placed in the hopper, h, and
gradually passing through the space, b, reaches the receptacle, c. In thus travers-
manner.
ing the furnace, or, more accurately, the portion thereof designated 6, the materials
become highly, heated, and in the case of lime and carbon, or their equivalents,
carbide of calcium is formed, which builds up immediately under the carbon,
lowers the electrical resistance, and causes the ampere meter, a³, if present, to
rise. The attendant, upon seeing this, operates the wheel, e, or otherwise rotates
or shifts the receptacle, c, in the direction indicated by the arrow in Fig. 1. By
this motion carbide is removed away from the arc or space designated b, and
fresh material sinks from the hopper into its place, ready to be acted upon in like
After continuing the process for some time, another plate, f, should
be added to the receptacle at substantially the point designated 1', in Fig. 1, in
order to retain the material in the receptacle, and fresh supplies must from time
to time, and slowly, be fed into the hopper, h, during the operation of the furnace.
The carbide is formed in the shape of a ring, or part of a ring, and when it has
become so long that it might interfere with the carbon, a¹, or other part of the
furnace, it being by this time cool, it can be broken off and removed, some of the
plates, f, at the right-hand portion of the furnace being taken off, if necessary,
for this purpose. The production of carbide, or other operation adapted to the
furnace, can in this manner go on indefinitely, or, at least, until the carbons are
entirely consumed. This furnace affords means for producing calcium carbide
in one continuous piece, and it also possesses other advantages. The carbide made
by it is all the same. Any piece of it is precisely like every other piece, whereas,
with furnaces heretofore employed, the carbide differed materially in quality,
being poor at the bottom of the furnace and rich in the middle and again poor at
the top. Also, such old furnaces had the disadvantage of entailing a considerable
waste of material, a comparatively large amount of coke and lime being caked
together in such a manner that they could not again be used unless re-ground and
re-mixed. Such. defects are absent from a furnace embodying this invention.
Another advantage is that in the described furnace there are no heavy weights
to lift. The greatest advantage incident to the use of the described furnace has

page_text: relation to the electrical machinery. In the old furnaces the demands on the
electrical generator were very variable for an hour or more after the furnace was
started, whereas, in the described furnace, the load on the electrical generator is
constant, and the advantage is very marked.
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. An electric furnace comprising the combination of means for producing an
electric arc in a substantially fixed position, a bottomless hopper for feeding the
material into the arc, an annular rotatable receptacle provided with movable plates
or covers and arranged below said hopper, and means for rotating said receptacle,
substantially as described.
2. An electric furnace comprising the combination of a bottomless hopper,
electrodes supported on the walls of said hopper, circuit connections for the
electrodes, a rotatable receptacle arranged below said hopper, and plates removably
applied to the periphery of said receptacle, substantially as described.
3. An electric furnace comprising the combination of an annular receptacle
having removable cover-plates, means for rotating said receptacle, and electric
devices for fusing and delivering material to the interior of said rotating receptacle,
substantially as described.