Improvements in and relating to Electric Furnaces.
Year: 1898

page_text: Date of Application, 22nd July, 1898-Accepted, 3rd Sept., 1898
COMPLETE SPECIFICATION.
Improvements in and relating to Electric Furnaces.
We, GEORGE LLEWELLYN PALMER, J.P., of Springfield, Trowbridge, in the
County of Wilts., Gentleman, and ERNEST WILLIAMS, of Clarendon, Trowbridge,
aforesaid, 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 :-
Our invention consists of certain improvements in and relating to electric
furnaces, its particular object being the production of calcium carbide by a
quickened process and with greater economy of heat as compared with existing
processes. It is applicable, however, to other electrical purposes, such as electrical
smelting, melting of metals, reduction of oxides, and the like. In all cases, we
are enabled by our invention to attain a higher degree of temperature within the
furnace compared with the strength of the electric current than has hitherto been
the case.
We attain this result by utilizing the heat generated within the furnace during
one operation for heating to a high temperature the charge which is about to be
introduced into the furnace for the next operation. The accompanying drawing
illustrates in perspective a convenient form of apparatus for carrying out this
process, and reference will hereinafter be made to the same.
The furnace A is adapted to run on a track B B, being mounted upon wheels C C.
We may construct the furnace of sheet iron lined with fire brick or of fire brick
or any other durable material, but instead of the usual sides, we provide large
removable blocks D D', one on each side, which we may term "electrode blocks."
In order that the interior of the furnace may be able effectually to withstand the
intense heat generated during the process, we line the floor and ends of the furnace
with some refractory material such as fire clay. The furnace may be rectangular
or any other desirable shape, but in every case left open at two opposite
points, such openings being occupied by the blocks D D' when the furnace is at
work.
The electrode blocks D D¹ are suspended by rods E E E E¹ firmly fixed into
or to the same and suitably hinged at the upper ends, for instance by cross
bars F F¹ carried in bearings G G¹ mounted upon beams or metal joists H H or
any other suitable framing or support. We provide means for enabling the
blocks D and D' to approach or recede from each other, for which purpose a rod J
is mounted in bearings K K¹ attached to the two pairs of rods E E and E¹ E¹
respectively, both the rod J and the bearings K K¹ being threaded right and left
handedly, so that the turning of J will move the blocks D D in relatively opposite
directions. The rod J may be provided with crank handles L as shown or any
other equivalent device.
The blocks D D' may be made of fire clay and each carries an embedded carbon
or metal plate or block M forming an electrode in electrical contact with the
terminal N.
Situated immediately above the furnace A is a feed box O, which for convenience

page_text: may be suspended to the framing H H by means of four rigid bars P. Said box O
may be made of carbon or other suitable material, in the bottom of which is a
draw plate P¹ We may for some purposes find it convenient to so suspend the
box O by means of levers or the like, that it can be raised or lowered at will.
Within easy distance of the furnace must be provided a variable power switch Q,
and one part of the cable R may be connected direct to the near terminal, the other
part passing beneath the rails, protected by a cover plate S, before being connected
to the other terminal N.
We close the electric circuit between the two electrodes M M by a thin carbon
rod T which is held between said electrodes by the pressure exerted by turning the
screw rod J.
Care should be taken to ensure that no portion of the current shall
pass from one terminal to the other excepting through the furnace, and the
blocks D D are therefore preferably made of some non-conducting substance or
may be insulated in any convenient manner from one another or from the
rods E E¹, or as shown in the drawing, the bearings K K¹ carrying the rod J can
be supported upon the rods E E' in porcelain bushes U.
The manner of operation is to first bring the furnace A below the feed box O and
adjust the carbon rod T in position between the blocks D D¹, each end bearing
against one of the electrodes M. The blocks D D' will now be in the position
shown on the accompanying drawing. The plate or slide P¹ is now withdrawn and
the contents of the feed box O fall into the furnace. The electric current is then
switched on, and while the furnace is becoming heated, another charge is brought
into the box 0, the plate P¹ being returned into position. In course of time
the heat given off from the furnace, both by radiation and by the burning gases
escaping therefrom, becomes so great that the charge gets heated to a very high
temperature while it is still in the feed box (). When the treatment within the
furnace is complete, the electrode blocks D D¹ are separated until they are clear of
the furnace ends (by turning handle L), and the furnace can then be wheeled away
and the molten mass allowed to cool, after which the furnace is cleaned out
preparatory to receiving the next charge, which, as already explained, has received
preliminary heating from heat which would otherwise have been wasted. Time
may be saved by employing three furnaces, one being in use, the other cooling,
and a third waiting to receive charge.
We prefer to use an alternating current from any suitable kind of alternator or
combination of alternators. The action of the rod T is the same as in all
incandescent electric furnaces; it first becomes heated to incandescence, heating
the mixture or substance in its immediate neighbourhood, finally becoming fused
and absorbed in the molten mass.
There are many ways in which we may modify the details of our invention
without departing from its main features. It is an essential feature of our invention
that the vessel containing the charge be heated previously to its introduction
within the furnace by the heat and burning gases given off from said furnace
during the electrical treatment of the previous charge. The feed box O, however,
may work on a pivot, if preferred, so that instead of having a slide in the bottom,
it may tip its contents into the furnace below. The manner of hingeing of the
electrode blocks D D¹ could be varied, for instance they might be carried upon bars
which extend downwardly below the level of the furnace, instead of upwardly as
shown.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what we
claim is:-
1. The combination with an electric furnace of a feed box or vessel containing
the charge adapted to be heated by the heat generated in the furnace during the
treatment of a previous charge, substantially as described.
2. An electric furnace in which are employed two oppositely situated blocks
occupying two openings or forming two sides therein and bearing (or themselves

page_text: constituting) the electrodes, said blocks being suspended or mounted upon rods
hinged either above or below the furnace and capable of adjustment away from or
towards one another, and adapted to hold between them the carbon rod, which
becoming incandescent produces the necessary heat within the furnace substantially
as described.
3. The improved process for manufacturing calcium carbide, or for smelting ores,
reducing oxides, and like purposes by electricity, consisting essentially in utilizing
the heat generated in the furnace during one final heating operation for giving
preliminary heat to the charge which is about to be introduced into the furnace for
the next final heating operation by means of apparatus such as shown by the
accompanying drawings and substantially as hereinbefore described.
4. The improved electric furnace and its appurtenances, substantially as described.
Dated this 21st day of July 1898.
For the Applicants,
STANLEY, POPPLEWELL & Co.,
61 and 62, Chancery Lane (7 and 8, Southampton Buildings), London, W.C.,
Chartered Patent Ager.is.