Improvements in and relating to Electric Furnaces for the Manufacture of Carbides.
Year: 1897

page_text: Date of Application, 8th June, 1897
Complete Specification Left. 8th Mar. 1898-Accented 8th June 1808
PROVISIONAL SPECIFICATION.
Improvements in and relating to Electric Furnaces for the
Manufacture of Carbides.
I, RICHARD MEMMO, of 58, Via Volturno, Rome, Italy, Engineer, do hereby
declare the nature of this invention to be as follows:-
-
This invention consists of a furnace intended for the manufacture of carbides in
general, but more particularly of carbide of calcium in which it is not necessary
to render the carbide liquid, whereby a great amount of electric energy is gained,
and water gas is produced as a bye-product of the reaction.
A construction of furnace according to this invention comprises a cast-iron box
provided with a lining of refractory bricks, open at its lower part to allow of the
issue of the carbide produced, and so as to form a reverberating furnace and a
movable bottom, a plate of graphite enclosed in a cast iron support which is capable
by means of a toothed rack and of its mechanism or of a rectangular screw, of
moving up and down like a piston in a tube of sheet iron, of a length proportionate
to the quantity of carbide which it is desired to remove each time from the furnace.
In the lower part of the tube there is a small morticed door to allow of the removal
of the block of carbide formed. The carbons (two for continuous currents or mono-.
phase alternating currents, and the requisite number of polyphase currents, that
is to say, one for each phase) are horizontal or inclined and in the centre of the
furnace. The carbons slide in the cast iron tube in an hermetic manner and are
operated by an arrangement of gear wheels for regulating the voltage. By this
means there can be produced, either simultaneous movement of the carbons, or a
partial movement of each carbon. With polyphase currents star arcs may be
employed, with the centre, either at the middle of the movable bottom or at the
end of any other inert carbon. Annular arcs may also be employed between the
carbons alone. At the upper part of the furnace is a receptacle of sheet metal lined
with refractory bricks into which the material to be treated is charged, viz. a
mixture of coal and slaked lime. This material may be caused to descend gradually
into the furnace above the arcs by the rotation of a small regulating helically
bladed screw, but for which any other mechanism may be used. Below the said
receptacle is a sheet metal casing by means of which the water gas evolved from the
furnace is able to reach holes pierced in the walls of the charging receptacle and
to burn in the mixture which in this manner is brought to a high temperature.
The air necessary for combustion is blown in a brickwork coil which surrounds the
pipe in which the bottom slides, and said air acts to constitute a protective layer
around the furnace and mingles finally with the water gas.
The air becomes heated in its travel by the heat radiated by the carbide already
formed in the pipe and by the incandescent walls of the furnace.
When it is not desired to utilize the water gas for heating the mixture, the said
gas may be led to the outside and be used for other purposes. I shall emphasize
the multifarious advantages of this arrangement in explaining the working of the
furnace.

page_text: As soon as the mixture has fallen upon the arcs, the carbide is formed, and the
continual lowering of the bottom allows the column formed to have a considerable
height without fear of inconveniences, because the current is not compelled to
overcome the resistance of said column as in other furnaces.
The centre of the arcs keeps always at the top of the cylindrical mass of carbide
and the diminution of the voltage shows clearly when the bottom must be lowered.
The distances of the arcs may also be regulated by means of this movable bottom
without having recourse to the use of toothed gearing.
As the carbide produced does not come in contact with the atmosphere, it does
not become oxidized, whilst the heat radiated as it is cooling is utilized to heat
the air blown into the mixture.
The proportions of the mixture are given by the following formula converted
into woights
As soon as the mixture has fallen upon the arcs, the carbide is formed, and the
continual lowering of the bottom allows the column formed to have a considerable
height without fear of inconveniences, because the current is not compelled to
overcome the resistance of said column as in other furnaces.
The centre of the arcs keeps always at the top of the cylindrical mass of carbide
and the diminution of the voltage shows clearly when the bottom must be lowered.
The distances of the arcs may also be regulated by means of this movable bottom
without having recourse to the use of toothed gearing.
As the carbide produced does not come in contact with the atmosphere, it does
not become oxidized, whilst the heat radiated as it is cooling is utilized to heat
the air blown into the mixture.
The proportions of the mixture are given by the following formula converted
into weights
Water gas.
CaH 02 + 4C=CaC₂ + 2 CO + H₂
74
48 64
56
2.
If the lime is not slaked, a certain amount of water is added to the mixture.
By this means the carbonic oxide which is evolved during the reaction in the
furnace, mingles with the hydrogen of the steam at a high temperature, whilst
the oxygen is converted anew into carbonic oxide with the product of the carbon
which is introduced for this purpose into the mixture. Consequently the furnace
yields water gas as a bye-product, the properties and use of which are well known.
It may, for instance, be employed as illuminating gas, heating gas, and for motive
purposes &c.
As soon as the pipe is full, the carbide produced is removed through
the mortice door, the bottom is raised and the operation may be recommenced.
But the working may also be continuous, and for this purpose, it is sufficient to
suspend by means of any suitable mechanism the upper part of the carbide formed,
remove the lower part and replace the bottom into contact.
In this manner I provide a furnace which works very regularly, in a continuous
manner and for a long period, whilst the continuous furnaces for liquid carbide
are damaged and rapidly placed out of use, especially by the passage of the carbide
along the walls of the tapping or outlet holes.
Dated this 8th dow of May 1807
The proportions of the mixture are given by the following formula converted
into weights
Water gas.
CaH 0+40 CaC₂ + 2 CO + H₂
56
74
48 64
2.
If the lime is not slaked, a certain amount of water is added to the mixture.
By this means the carbonic oxide which is evolved during the reaction in the
furnace, mingles with the hydrogen of the steam at a high temperature, whilst
the oxygen is converted anew into carbonic oxide with the product of the carbon
which is introduced for this purpose into the mixture. Consequently the furnace
yields water gas as a bye-product, the properties and use of which are well known.
It may, for instance, be employed as illuminating gas, heating gas, and for motive
purposes &c.
As soon as the pipe is full, the carbide produced is removed through
the mortice door, the bottom is raised and the operation may be recommenced.
But the working may also be continuous, and for this purpose, it is sufficient to
suspend by means of any suitable mechanism the upper part of the carbide formed,
remove the lower part and replace the bottom into contact.
In this manner I provide a furnace which works very regularly, in a continuous
manner and for a long period, whilst the continuous furnaces for liquid carbide
are damaged and rapidly placed out of use, especially by the passage of the carbide
along the walls of the tapping or outlet holes.
Dated this 8th day of May 1807
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
Improvements in and relating to Electric Furnaces for the
Manufacture of Carbides.
I, RICHARD MEмзо, of 58, Via Volturno, Rome, in the Kingdom of Italy, 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 relates to electric furnaces destined for the manufacture of
carbides generally and more particularly of calcium carbide, in which it is not
necessary to render the calcium carbide fluid whereby a great amount of electrical
energy is saved and water-gas obtained as a bye-product of the reaction.

page_text: In the diagrammatic view Fig. 1,
A is a cast iron casing or box lined with refractory bricks and open at the
bottom to enable the carbide produced to be discharged, and forms a reverberatory
furnace. Bis a movable bottom, and consists of a plate of graphite in a cast iron
frame which can be lowered or raised like a piston in a tube or casing T made of
sheet metal, by means of a rack and pinion or a screw. The length of the tube T
depends on the quantity of the carbide which is to be withdrawn at a time from
the furnace.
A. sliding door in the lower portion of the tube enables the carbide to be with-
drawn.
C are the carbons (two for continuous or alternating monophase currents the
number for polyphase currents being one carbon more for each phase). These
carbons are arranged horizontally or obliquely and are so placed that their ends
extend to the centre of the furnace. The carbons slide in cast iron tubes closed
in an air tight manner and are operated by, say, a system of gear wheels for
regulating the voltage. The carbons may be caused to move either both simul-
taneously or cach separately. With polyphase currents may be used either a
star-shaped are with the centre in the middle of the movable bottom, or with the
centre at the end of any other inert carbon, or an are in the shape of a ring
between the carbons only may be employed.
In the operations of melting and reducing in which the dispersing and
unsettling action of the voltaic arc is to be avoided heat may be also generated
in the furnace without producing any voltaic arc at all. This is effected by
connecting the terminals of the phases with small rods made of substances which
are bad conductors of electricity (such for instance as carbon, various compositions,
refractory oxides etc. These substances will become incandescent when the electric
current passes through them and will fulfil in the furnace the function of voltaic
arcs the regulation of heat being just as easily effected as for the arcs while the
working goes on in a more stable manner.
To use polyphase currents, acting by rendering substances incandescent, small
rods are arranged either in a star shape or in the shape of a ring that is to say,
either by connecting the large carbons supplying the currents of a phase with a
central point or connecting each carbon with the adjoining ones.
D is a sheet metal receptacle lined with refractory material or bricks into which
is introduced the material to be treated, say a mixture of carbon and slaked lime.
This material descends into the furnace till near the arcs or the small incandescent
rods, a small regulating helically bladed screw being employed to feed it forward
which screw can be however replaced by any other suitable mechanism.
E is a sheet metal casing through which the water-gas produced in the furnace
can collect, and pass through passages in the walls of the filling receptacle and
burn in the mixture which is thus strongly heated. The air required for com-
bustion is supplied by means of a coil, S, made of bricks or sheet metal and
surrounding the tube T in which slides the bottom, it then forms a protective
layer round the furnace and is finally mixed with the water gas.
During its passage, the air is heated by the radiating heat of the carbide
already formed in the tube T and by the incandescent walls of the furnace.
When it is not desired to use the water gas for heating the mixture said gas can
be conducted outside, and used or stored for other purposes.
Thus with the device shown in Fig. II the gas may be burned in the interior
of the furnace as it is being generated. To effect this it is sufficient to inject into
the upper portion of the furnace atmospheric air in a quantity sufficient for perfect
combustion of all the gas generated.
The crucible of the furnace is extended at the top by a rounded dome, protected
by means of a refractory casing, and to which several nozzles or openings r supply
air. It is obvious that in the furnaces according to this invention air may be used

page_text: which has been previously heated by the radiating heat of the carbide, whereby
the thermic efficiency of the furnace will be still more increased.
The advantages of this arrangement will now be shown in explaining, the
working of the furnace.
As soon as the mixture falls on the arcs carbide is generated, and the continuous
lowering of the bottom enables the column produced to reach a considerable length
without fear of any inconvenience, as the current is not obliged to overcome the
resistance of this column as in other furnaces. The centre of the arcs is always
maintained at the top of the cylindrical mass of carbide and the decrease of voltage
clearly indicates when the bottom or carrier is to be lowered. Thus by means of
this movable bottom it is possible to regulate the distances of the arcs.
In fact
if the carbons are stationary and the arcs are formed in the shape of a star with a
centre on the movable bottom, it is obvious that to each movement of the bottom
and consequently of the centre of the arcs will correspond a variation in the
length of the arcs. It is possible, therefore, in the star-arrangement, to regulate
the voltage of the arc simply by means of the bottom without having recourse to
the movement of the carbons. Of course this is impossible in the ring arrange-
ment, since the arcs are independent of the movable bottom.
The carbide produced not coming in contact with the atmosphere does not
become oxidised while the heat radiated by it is utilised to heat the air injected
into the mixture.
CaH₂O₂ +4 C = Cat, +2:00 + H₂ (water-gas.)
74 +48
-
64 +56 + 2.
The
If the lime is not slacked, a certain quantity of water is added to the mixture.
In practice the materials forming the mixture are finely pulverised, mixed with
any liquid or pulverised glue, and then compressed so as to form bricks.
bricks thus obtained are dried or re-burned and then broken into small pieces or
particles in which shape they are introduced into the furnace. This ensures a
more regular working of the furnace and prevents the formation of dust which
causes loss of material and is injurious to the health of the workmen.
The oxide of carbon liberated during the reaction in the furnace becomes mixed
with the hydrogen of the steam at a high temperature, the oxygen again forming
carbonic oxide by combining with the excess of carbon introduced for that purpose
in the mixture.
The furnace consequently gives as a bye-product water gas the properties and
use of which are well known. It may be used for lighting, heating or as motive
It may be also burned in the interior of the furnace for considerably
increasing the thermic efficiency of the latter.
power etc.
As soon as the tube T is full the carbide produced is removed through the
sliding door the bottom is raised and the operation started afresh
But the working may be also rendered continuous and for this purpose it 13
sufficient to suspend or hold up, by means of any suitable mechanism, the upper
portion of the carbide produced, to remove the lower portion and to replace the
bottom in contact with the upper portion of carbide. The mechanism used for
holding up the carbide column may consist simply of a castiron ring formed into
three sections and arranged in the interior of the tube T as shown in Fig. 3. The
three sections may be advanced or withdrawn as desired by means of three
screws V operated by a key from the outside of the furnace. In their advanced
position the carbide column is grasped as by three jaws and consequently it is
suspended and the lower portion of the charge can be removed. If on the con-
trary the sections are withdrawn, the column is free to rise or descend, according
to the movement of the movable bottom. In this way a furnace is obtained which

page_text: can be worked for a very long time in a continuous and uniform manner while the
continuously working furnaces hitherto known producing liquid carbide soon get
out of order especially as regards the passage of carbide through the discharge
passages.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is: -
1. In an electric furnace a movable piston bottom enabling either the whole
mass of material produced to be removed or any part of it to be removed without
interrupting the working of the furnace substantially as described.
2. In an electric furnace the regulation of the arcs by means of the movement
of the bottom as well as by toothed gearing connected to the carbons said regula-
tion being also adapted for use when the furnace works by incandescence
substantially as described.
3. The production of a continuous column of calcium carbide without loss of
current substantially as described.
4. In an electric furnace the combination or arrangement of carbons so as to
obtain star-shaped arcs for the purpose of utilizing polyphase alternating currents
or the arrangement in the shape of a star or of a ring of small rods connecting
the terminals of the same phase so as to use these currents by incandescence
substantially as described.
5. In an electric furnace means for cooling the mass of the carbide without
contact of the atmosphere so as to prevent its oxidation the radiating heat being
utilized for heating the air used for the combustion of the water-gas formed
substantially as described.
6. In the production of calcium carbide in an electric furnace the formation of
water-gas and its use either in the interior of the furnace by burning it to increase
the thermic efficiency of the apparatus or outside for any purposes such as heating
lighting or motive power substantially as described.
7. The combination and arrangement of parts constituting the complete electric
furnace substantially as described and illustrated in the accompanying drawings.
Dated this 8th day of March 1898.
BOULT & WADE,
Agents for the Applicant.