Improvements in Electrical Furnaces.
Year: 1899

page_text: Date of Application, 17th Apr., 1899-Accepted, 27th May, 1899
COMPLETE DITUITIVATION.
Improvements in Electrical Furnaces.
We, DENIS LANCE, Doctor of Science, RAPHAEL LOUIS EMMANUEL DE
BOURGADE, Doctor of Medicine, and LEON SCHMITZ, Engineer, all of No. 5,
Place Saint Michel, Paris, France, 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:-
This invention has reference to improvements in the construction of the
electrical furnace described in the Specification to our Application for Letters
Patent dated 27 March, 1899, No. 6582. The present improvements relate in the
first instance to the method of heating the electrical furnace. Generally speak-
ing, the method of heating is the same as that described in the said specification,
that is to say, it consists in causing an electric current to pass through con-
ductors arranged externally and near to the two walls of the furnace which are
at a small distance from each other, this being the only means of obtaining a
sufficiently high and uniform temperature at all points of the furnace, which is
necessary for certain operations, and especially for the manufacture of cyanides
by the process based on the employment of hydrogen, nitrogen, ammonia, and
carbon. But instead of arranging close to the furnace walls a series of vertical
conductors through which the current is successively sent by means of a rotatory
distributing device, we provide two helically arranged conductors in communica-
tion with each other, and through which the current is made to flow continuously.
A rheostat interposed between these coils and the source of electrical energy
enables the degree of heat to be regulated at will.
Or according to another modification we retain the arrangement of conductors
described in the said previous specification (two series of vertical conductors) but
we cause the whole of the electric current to pass continuously through all the
conductors, the distributing device being consequently dispensed with.
regulation is effected as in the previous case by means of a rheostat.
The
Our improvements also relate to means for preventing loss of heat due to
radiation.
In the furnace of annular form described in our said previous specification the
loss of heat by radiation was prevented as to the one wall of the furnace, namely
the inner one, by reason of the annular form, but the outer wall was not pro-
tected against radiation.
According to our present invention we remedy this disadvantage by enclosing
the outer wall of the furnace with a covering of a bad conductor of heat. The
use of a covering of this nature also has the advantage of enabling us to impart
to the furnace a rectilinear or rectangular form when required. In this case the
casing is of course made to entirely enclose the furnace, so as to cover both its
long sides, and not only the one side as in the case of the annular furnace.
If however several furnaces of rectangular shape be placed side by side, which

page_text: con-
we mav in some cases do, the casing may be ommitted at the contiguous sides
of two such furnaces, as the heat will only be radiated from the wall of the one
furnace on to that of the other, so that the heat would not be lost. The same
remark would also apply in the case of two or more annular furnaces of different
diameters arranged concentrically one within the other, which may also be done.
On the accompanying drawings are shewn by way of examples, some
structions of electrical furnaces having our said improvements applied thereto.
Fig. 1 shews a vertical section of an annular furnace having our said improve-
ments applied thereto, and constructed in the proportions which are most suited
for the manufacture of cyanides by means of hydrogen, nitrogen, ammonia and
carbon, the heating being obtained by means of two helical coils of suitable con-
ducting material, Fig. 2 is a horizontal section of the furnace on the line A B
Fig. 1. Fig. 3 is a vertical section of a furnace of annular form as in Fig. 1 and
provided like this with a casing which is a bad conductor of heat, but with the
heating conductors arranged in the same way as in the said former specification,
that is to say, two sets of vertical wires through which the current is conveyed
by means of a distributing device.
Fig. 4 is a front view of the distributor. Fig. 5 is a vertical cross section of a
rectilinear or rectangular furnace, entirely surrounded by a casing of a bad heat
conducting material. The method of heating is assumed to be the same as that
shewn at Fig. 3, but there may be substituted for it the arrangement of heating
coil as at Fig. 1. In all the figures the same letters of reference indicate the
same parts. A and B Figs. 1, 2, 3, and 5, are the two walls of the furnace
which are separated from each other by a small space, and which are of porcelain
or other suitable refractory material. C is the supply pipe for the gases and Dis
the discharge pipe for the same. The upper part E of the space between the
walls A and B which is filled with fragments of porcelain or other refractory
material, constitutes the chamber for the supply of the gases. The lower
part F of the said space constitutes the reaction chamber which contains the
substances upon which the gases are to react.
If for example it be required to manufacture cyanides by the above mentioned
process, this chamber will contain either fragments of carbon or perforated carbon
plates, or small carbon rods. G, Figs. 1 and 3 is a casing of refractory material,
the space between which and the wall of the surface is filled with a mixture of
sand and asbestos, or with any other suitable material that is a bad conductor
of heat.
In the constructions at Figs. 3, 4 and 5 the furnace chamber F is heated on
both sides by a series of conducting wires or strips H, fixed at one end to a
conducting band I to which the current is led by a conductor J, and which each
terminate in one of the blocks K connected to block K¹ of the current distributor.
Over these blocks travels a block L fixed to an arm M that revolves on a central
axis so that the electric current will thereby be sent successively into each of
the different wires H.
The block L is of such a width that it is always in contact with one of the
blocks K' before it leaves another of them so that there is no interruption of
current.
However, according to one of our present improvements, we prefer to dispense
with the rotating distributing device and allow the current to pass continuously
through all the conductors H, in which case of course the insulated blocks K
are no longer necessary and the second end of the conductors H is merely con-
nected to a conducting band similar to the band I to which their first end is
connected.
In the arrangement at Fig. 1, the heating is effected by means of two helical
conducting coils N N¹ communicating with each other and connected to the
source of electrical energy, a rheostat O being interposed in the circuit, as in
the preceding case. P P are dwarf walls or other supports for carrying the
furnace.

page_text: Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, we declare that
what we claim is.--
con-
1. In an electrical furnace heated externally by means of conductors
stituting resistances, the use, for the heating conductors, of two helically coiled
wires or bands connected with the source of electrical energy, and arranged close
to the furnace walls, substantially as described.
2. In an electrical furnace heated externally by means of conductors, con-
stituting resistances and arranged near the furnace walls, the use of jackets or
casings of a bad conductor of heat enclosing those walls that are not situated
near to a heated wall belonging either to the same furnace or to a different one,
substantially as described.
Dated this 17th day of Anvil 1800