Improvements in Electric Furnaces or Electric Heating Apparatus
Year: 1897

page_text: Date of Application, 25th May, 1897-Accepted, 31st July, 1897
[Communicated from abroad by ALFRED HUTCHINSON COWLES of Cleveland, in the
State of Ohio, United States of America.]
Improvements in Electric Furnaces or Electric Heating Apparatus.
I ALFRED VINCENT NEWTON of the Office for Patents, 6, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, 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 object of the present invention is to provide an electric furnace or apparatus
into which a gas is passed, and a method of operating such a furnace, which shall
admit of economical results being obtained that have not heretofore been possible.
The admission of air or of gas or vapour producing fluid into an electric furnace has
heretofore been practised, but the gas, or the fluid, has always been introduced
through a single inlet pipe, or in a uniform direction, and likewise, where specific
means have been provided for the discharge of gas from the furnace or chamber, it
has been taken off through an.outlet pipe or passage, and always at the same point
of discharge. Further, the flow or course of the gas through the furnace chamber; or
through or over electrically heated material or surface therein, or of a gas-generating
fluid which vaporizes on entering the furnace or chamber, and then passes as gas
therethrough, has always been constant, whenever it has been given any direction,
and hence the effect of the steady outflow of gas from the furnace chamber, or through
a mass of material through which the gas passes, tends to excessively heat the furnace,
or the body of material, on the side of, or in the vicinity of, the line of discharge, and
also the gas carries with it, and deposits on the discharge side, or in the interstices of
the mass along the lines of flow towards the point of discharge, soot, dust, and fine
particles, which clog the interstices, and interfere with the obtaining of the best
results. Suppose, for example, we have a body of granular or broken carbon, carbon
and ore, or other material, with a field of intense heat in the centre of the mass,
evolving gases which must find vent, or suppose, in such a case, a stream of gas is
being injected into the mass, which gas passes through the zone of heat and then
passes out, the gases flowing outward from the heated area are at a very high
temperature, and gradually heat up the mass adjacent to its path of outflow,
gradually extending the field of intense heat farther and farther from the central
zone in the direction of the outlet, until, along this line of flow, the temperature of
the mass approximates to the temperature of the central field, while on the inflowing
side of the field the temperature of the mass is relatively low. Likewise, if we have
an electrically-heated open-chamber through which there is a flow of gas, or an
electrically-heated surface, or series of surfaces within an enclosure, over which
surfaces there is a flow of gas in a constant direction, the hot gases heat up the dis-
charge side of the enclosure, or the avenues of exit, far above the temperature of other
parts of the chamber away from the zone of high heat.-And, as before stated,
particularly in the case where there is an interstitial mass through which the gas
flows within the chamber, or immediately after leaving it the particles of soot, dust,
or sublimated matter carried outward from the zone of heat by the outflowing gas,
are deposited, to a greater or less degree, as soot, dust, or an amorphous or crystalline

page_text: powder, along the avenues of flow, and clog the passages. In the case of a granular
mass, or a granular mass mixed with fine material, or a mass of finely-divided ore and
other material electrically heated at the centre, with gas working outward therefrom
to the surface, in some cases little mounds with craters are formed at the points of
outlet, with the intensely heated area extending from the centre along the path of the
outflow close up to the crater.
This action of the outward extension of the field of heat along the lines of exit of
the gases from the centre of a granular mass, clearly shown in the working of the
electric furnace of the Cowles incandescent type, wherein there is a body of granular
material with a central zone of heat; nor is such effect entirely absent when there is
coupled therewith an arc effect, as, for example, when the process is carried on in a
chamber on the principle of a Siemens arc furnace.
Under the conditions ordinarily existing during the running of such furnaces, where
there is a mass of fused ore and granular carbon forming a spongy or a thick, pudding-
like mass, or an overlying layer of such a character, the gases work upward or outward
to the surface along the channels of easiest passage, and extend the central heat along
such lines more rapidly than in other directions. The same effect is true where a gas
has, by reason of entering at a certain point, and discharging at another fixed point,
an approximately constant line of flow through the mass or through the chamber.
It is the object of the present invention to control this field of heat, and to effect a
more uniform distribution or extension of the zone or area of intense heat, and a more
effective and uniform action of the gas passed therethrough, and this I secure by
periodically or at times changing the direction of the course of the current of gas
Howing into or through the chamber of an electric furnace, or over the electrically
heated surfaces, or through a mass' or body of electrically heated matter, so that the
course of the hot gases leaving the heated area or centre will be changed.
This improvement is especially directed to the treatment of a gas for the production
of an illuminating or a heating gas, or to the utilization, for illuminating, heating, or
other purposes, of the waste gases of an electric furnace.
As an illustration of the principle of the invention and its effects, I will describe it
in connection with an interstitial mass in an electric furnace, through which there is
flowing a stream of gas; though it will be understood that it is not limited to the
specific conditions here existing, but applies to any electrically heated chamber,
surface, or mass, through or over which there is caused to pass a current of gas, or a
current of gas-producing materials.
In the accompanying Drawings, Fig. 1 is a sectional plan of an electric furnace,
and
Fig. 2 is a sectional elevation of the same on the line 2-2 of Fig. 1.-
A is a furnace chamber filled with a charge, B, of granular or broken coke, for
example, or other suitable material, it matters not what; and C is an electrode
leading down into the mass; the bottom of the furnace chamber forming the other
electrode. The upper electrode is adjustably supported in any preferred way. For
example, the upper end, c', of the holder is screw-threaded, and engages with a hand-
wheel nut c², properly supported by a girder c³-One of the electric cables is attached
to the holder at c.-Provision is made for cooling the carbon holder by means of a
flow of water therethrough. The lower part of the holder is made hollow, and pro-
vided with a water-pipe c' leading into the bottom of the hollow chamber within the
rod, and with a water discharge pipe co at the upper end of the same.
The furnace chamber or crucible is also provided with a water jacket a¹, and with
water pipes a², a", for the inflow and outflow of water therefrom. Electrical connec-
tion is shown as made with the outer iron shell of the furnace at a, the current passing
through the carbon filling or block A' to the charge in the furnace chamber. Extending
laterally from opposite sides of the furnace chamber, and a sufficient distance above
the bottom of the same to form a sump D, there are the lateral flues, passages, or
pipes, E, E¹, diametrically opposite, and leading outward through the furnace walls,
and filled with coarsely granulated or broken carbon or coke e, the interstices of the
same forming carbon lined passages for the gas. These interstices in the bodies of

page_text: broken carbon flanking the furnace chamber, form, on each side thereof, a group of
flues or channels through which the gas has to pass on entering and leaving the
chamber, and, the mass being of carbon, the channels have surfaces or linings which
are able to withstand the extremely high heat, and the flues remain open.-Carbon
is the only material available which will stand the high temperature to which
these channels are subjected, without fusing or running.
The passages through the interstitial bodies of carbon, are as efficient flues for gas
flow as those formed with straight or regular walls.
Connected with these flues E, E¹, are the gas pipes F, F respectively, properly
protected by water jackets f, f, said gas pipes leading into the reversing valve
chamber G, which chamber has a gas-supply pipe H and a gas-discharge pipe
I, which may, for example, lead to a gasometer, or to such apparatus as may be
proper for the subsequent treatment or handling of the product. The furnace
chamber is indicated as filled to the top with coarse and fine carbon, and if the charge
is covered over with a surface covering of fine carbon b, it is a sufficient closing-in of
the furnace chamber for the treatment of gases under light pressures. The chamber
may, however, be completely closed in and sealed or luted.-
K is a tap-hole for drawing off any molten material accumulating in the sump.
In operation, the furnace having been heated up electrically to the point where
the temperature of the interior of the carbon charge or mass in the chamber is high
enough for working, the gas is admitted through one of the pipes F, E, for example,
and passing through the interstices of the carbon body B, and through the central
field of heat, where the chemical change in the gas takes place, or the major portion
of the same is effected, that being the field of the greatest electrical energy, it flows
outward through the passage E1, and the interstices of the carbon e, filling the same,
in the present case, and through the pipe F1, and the proper channel in the reversing
valve G and the discharge pipe I.-The heated gas passing through the central
intensely heated field, to and through. the flue E¹, gradually extends the field of heat
in the direction of this point of exit, while the inflowing current of gas cools the
opposite side of the chamber, and gradually works the edge of the sphere or zone of
heat inwards towards the centre of the mass. The centre of the zone of highest heat,
barring an arc centre, by reason of the carrying inward of the heat on the inflowing
side, and the carrying outward of heat on the outflowing side, is thus being gradually
moved towards the point of exit of the gas from the chamber. The particles of soot,
dust, and sublimated matter picked up and carried along by the gas currents, are,
on the outflowing side, carried inward towards the centre of greatest electrical activity,
and the region most favourable for the chemical changes, thus clearing out and
opening up the channels for the free passage of the gas through the mass on that
side, while, on the side of exit, the gas currents, as they get away from the heating
field, deposit within the interstices of the mass, and of the exit passage, the dust,
soot, and sublimated powders carried by them. After the gas has been flowing
through the furnace for a proper interval of time, the reversing valve G is shifted,
making connection of the gas-supply pipe H, with the pipe F, and of the pipe F,
with the gas discharge pipe I. The flow of gas is now through the furnace chamber,
from the flue E¹, to the flue E, in the opposite direction from what it has been
flowing, and in an opposite direction through the interstices of the carbon charge B
in the furnace. The effects above set out now occur in the opposite direction.
The area of intense heat, which extends laterally towards the flue E¹, now
moves inwards, and travels towards the new point of exit, the flue E, and the
deposited fine matter in the interstices of the mass is carried back into the heated
field, while the formation of new deposits in the interstices of the mass on the
opposite side and in the flue E may be forming.-
Thus, with a proper periodical reversal of the gas valve, it will be seen that there is
secured a perfect control of the field of heat in the furnace, and it can either be held
central by making the reversals of the flow sufficiently frequent, or it can be caused
to move to and fro. This movement of the field of heat is the most marked in an
incandescent mass where there is no fixed arc centre. It may be assumed that the

page_text: heat can then be bunched, and the centre of greatest heat moved along the line of the
flow of the gas through the mass to the point of exit, and then caused to travel back
again, and to and fro.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed (as communicated to me from
abroad), I declare that what I claim is :-
•
1. In an electric heating apparatus, the combination with a chamber, of an electric
circuit connected therewith, and adapted to produce a zone or area of electric heat,
separate gas inlet and outlet passages connected with said chamber, and means for
periodically reversing the flow of gas therethrough, as and for the purpose set forth.
2. In an electric furnace, the combination with the furnace chamber, of an electric
circuit connected therewith, and adapted to create a zone of electrical heat within the
furnace chamber, of inlet and outlet gas flues, and interstitial bodies contiguous to
the zone of electrical heat, and in the path of the inflowing and outflowing gases,
together with means for reversing the flow of gas therethrough, as and for the purpose
set forth.
3. The combination with an electric furnace chamber, of lateral apartments filled
with broken carbon, and forming gas passages for the inflow and outflow of gas, in
combination with gas pipes connected with said apartments, and a reversing valve
to control the direction of the flow through the furnace, as and for the purpose set
forth.
4. In an electric furnace, a furnace chamber adapted to be charged at the top, and
having a central and adjustable electrode carried by a water-cooled holder, such
electrode extending down into the chamber, lateral gas inlet and outlet. flues or
passages opening into the furnace chamber, and filled with granulated or broken
carbon, together with gas connections with said inlet and outlet flues or passages, for
the supply of gas to the furnace chamber, and the removal of the same therefrom, as
and for the purpose set forth.
Dated thin orth dog of M 1907