Improvements in and Connected with Electrical Furnaces.
Year: 1888

page_text: Date of Application, 22nd Sept., 1888
Complete Specification Left. 21st June, 1889-Accepted, 21st Sept, 1889
PROVISIONAL SPECIFICATION.
Improvements in and Connected with Electrical Furnaces.
I, ROOKES EVELYN BELL CROMPTON, of Arc Works Chelmsford Electrical
Engineer, do hereby declare the nature of this invention to be as follows :—
In
My invention relates to improvements in Electrical Furnaces, in which a bed of
carbon mixed with the ores or other materials to be dealt with is wholly or partially
maintained at a high temperature by the heating effect of the passage of the
electrical current. My improvements consists in the application of sources of heat,
other than the electric power itself for the purpose of raising the temperature of the
contents of the furnace to a desired degree before the electric current is switched on.
I effect this in various ways. In one case supply a gas generating apparatus in a
position conveniently near to the furnace; this gas producer may be of the well
known Siemen's type, but any suitable form of gas producer may be used, whose gas,
mixed with the proper amount of air can be burnt so as to give a non-oxidising
flame. The gas may be introduced into the furnace by a series of burners tuyeres,
either projecting through the bottom of the furnace to a sufficient distance to prevent
them being blocked by reduced metal or by slag or through the sides or ends of
the furnace or it may be introduced by moveable jets projecting through the cover
of the furnace as may be most conveniently arranged to suit the furnace itself.
case it is desired to carry the gases well into the body of incandescent carbon, I some-
times provide temporary nozzles made of material which will not injure the contents
of the furnace if melted by its action; for instance in the furnace producing ferro-
aluminium I use iron pipes, or Cupro-aluminium, copper pipes. Another method I
sometimes use for heating the contents of the furnace is providing separate chambers
at its two ends, into which the burning gas is delivered. The heated gases are
allowed to flow in annular stream, concentric with the carbon electrodes, through
which the electric current is passed into the furnaces. The walls & covering of these
annular passages, may be made as before of the suitable metal, or they may be made
of retort carbou. In any case the working of the furnace is as follows. When the
furnace has been duly lined, & charged, one or more pilot or small jets of gas are
lighted in any convenient manner, the main current of heated gas is then gradually
turned on from the gas generator. This is lighted by the pilot jets, or it may be
lighted at the mixing chambers at the ends of the furnace above mentioned. The
jets of gas play through the active part of the charge of the furnace, to a sufficient
extent to raise the whole to a state of low incandescence.
The degree of temperature which may be reached in this manner before the
electrical current can be switched on, can be adjusted to suit the contents. By this
method of heating the contents of this class, of electric furnace, I effect a large
saving in the time during which it is necessary to apply the electric current &
consequently in the cost of the latter.
Instead of using gas for heating I sometimes prefer to heat the charge by burning
coke or coal or part of the charge itself. All that is then required is to arrange the
charge so that it forms part of an ordinary furnace. It is lighted & a small
draught permitted so that it gets to a uniform white heat. The draught is prefer-
ably stopped before the current is switched on.
Dated this 21st day of Senember 1888.

page_text: COMPLETE SPECIFICATION.
Improvements in and Connected with Electrical Furnaces.
I, ROOKES EVELYN BELL CROMPTON of Arc Works Chelmsford, 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 :-
My invention relates to improvements in electrical furnaces in which a bed of
carbon mixed with the ores or other materials to be dealt with is wholly or partially
maintained at a high temperature by the heating effect of the passage of the electric
current. My improvement consists in the application of sources of heat other than
the electric power itself for the purpose of raising the temperature of the contents of
the furnace to a desired degree before the electric current is switched on. I effect
this in various ways.
In one case I supply a gas generating apparatus in a position
conveniently near to the furnace. This may be of the well known Siemens type but
any suitable form of gas producer may be used, to produce gas which when mixed
with the proper amount of air can be burned in such a manner as to give a non-
oxidising flame. The gas may be introduced into the furnace through a series of
burners or tuyeres which may be arranged so as to project either through the
bottom of the furnace to a sufficient height to prevent them being blocked up by the
reduced metal (or by the by-products) or through the sides or ends of the furnace,
or the heating gas may be introduced through moveable jets projecting through the
cover of the furnace as may be found most convenient to suit the various forms of
furnaces. In such cases where it is desirable that the gases should be carried to an
advanced position well within the body of incandescent carbon I sometimes provide
temporary nozzles made of such material that if it be melted by the action of the
furnace will not injure the contents of the furnace. As for instance in the furnace
producing Ferro-aluminium I use iron nozzles, or in the furnace producing Cupro-
aluminium I use copper pipes. In other methods I sometimes heat the contents of
the furnace by providing separate chambers at its two extremities into which the
heated gases may be delivered and from these allowed to flow through annular
passages concentric with the carbon electrodes used in these electric furnaces.
some cases the temperature of the gases may be so arranged that although after
ignition it may be high enough for the purpose of raising the contents of the furnace
to the desired degree yet previous to ignition its temperature will not be so high
as to burn away the surface of the carbon electrodes over which the gases pass on
their way to the furnace, and in this way the portion of the carbon electrodes not
absolutely protruding beyond the annular passages will be protected from the action
of the incandescent fuel of the furnace, and so the duration of the electrodes will be
prolonged. The walls and covering of these annular passages may be made as before
of the suitable metals as above described or they may be made of retort carbon, or
they may be built of similar material to that used for the lining of the furnace. The
working of these furnaces may be described as follows:-
In
After the furnace has been duly lined and charged with its proper charge of ore
and carbon and other materials, one or more pilot lights or small jets of gas are
lighted in any convenient position; the main current of heated gases is then gradually
turned on from the gas generator; this being lighted at the pilot jets, gradually
raises the contents of the furnace to a state of low incandescence. The degree of
temperature which ought to be reached at this stage must be determined by the
nature of the contents of the furnace. The electrical current is then switched on,
and processes of reduction or other processes usually carried on in such electric
furnaces can be completed. It will be seen that by my improvement a great saving
can be effected in the time during which the electrical current must be switched on
to each individual furnace so that a much smaller plant of electric generating
machinery is required to work a given number of furnaces. Although I more
particularly describe methods of using gas for heating the contents of the furnace in

page_text: certain cases I can arrange that part of the contents of the furnace can be ignited
and by burning itself contribute the heat required to raise the remainder of the
chargo to a state of low incandescence or any desired temperature previous to the
switching on of the electric current. I am aware that the use of furnaces in which
high temperature is maintained by the heating power of the electric current is not
novel.
Sheets 1, 2 and 3 show an elevation and plan of 3 forms of the furnace. Fig. 1
shows a side view of an electric furnace surrounded by a chamber into which the
mixture of air and gases are delivered from the gas producer. aa a are the nozzles
through which in this case the gases are delivered into the body of the furnace. In
Figs. 1. 2. 3. 4. 5. 6 C are the carbon electrodes, surrounded by D the furnace
contents E E are the walls of the furnace 2 F the moveable cover.
Fig. 2 shows a similar furnace but with mixing chambers only at the two ends
from which the gases can pass by annular passages surrounding the carbon electrodes
as shown.
Fig. 3 shows in side view and 4 in plan view a similar furnace but with the air
and gases arranged in the form of a Bunsen burner, having 2 concentric tubes A & B,
A to supply the gas & B to supply the air, the products of combustion being carried
away by the tube D' on the opposite side of the furnace.
Figs. 5 and 6 show a somewhat similar arrangement but with the tubes A & B
carrying the air & gases introduced at one end and the products of combustion being
taken away by the tube D' at the other end.
In these last two cases the contents of the furnace is heated by the incandescent
gases playing over its upper surface, and the injecting nozzles being removed from
the zone of extremely high temperature are not so likely to be fused off or otherwise
damaged.
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. In electric furnaces, the division of the operation of working the furnace into
two parts during the first of which the temperature of the contents of the furnace is
raised to a desired degree by means of sources of heating other than that of the
electric current itself.
2. In electric furnaces the combination of ignited heated gases introduced into the
furnace by a series of burners or tuyeres substantially as described for the purpose of
raising the temperature of the furnace to any desired degree previous to its operation
by means of the electric current.
3. In electric furnaces the application of temporary nozzles for these jets made of
material which will not injure the working of the furnace substantially as described.
4. In electrical furnaces the arrangement of annular passages concentric with the
carbor. electrodes for the purpose of introducing the heating gases and for protecting
the carbon electrodes substantially as described.
5. The arrangements of the contents of electrical furnaces in such a manner that
part of the charge may be ignited for the purpose of partially heating the contents
previous to the introduction of the electric current.
Dated this 20th day of June 1889.
ROOKES EVELYN BELL CROMPTON.