AN IMPROVED ARRANGEMENT OF A REGENERATIVE SIEMENS' FURNACE
Year: 1876

page_text: LETTERS PATENT to Ludwig Haarmann, Engineer, in the City of Hannover,
Kingdom of Prussia, Empire of Germany, for the Invention of "AN IMPROVED
ARRANGEMENT OF A REGENERATIVE SIEMENS' FURNACE."
ealed the 2nd March 1877, and dated the 22nd September 187
PROVISIONAL SPECIFICATION left by the said Ludwig Haarmann at the
Office of the Commissioners of Patents on the 22nd September 1876.
LUDWIG HAARMANN, Engineer, in the City of Hannover, Kingdom of Prussia,
Empire of Germany. "AN IMPROVED ARRANGEMENT OF A REGENERATIVE SIEMENS'
FURNACE,"
In the construction of the Siemens' regenerative gas furnaces heretofore used it
was not possible to obtain on the hearth a flame merely reducing or oxidating, such
as is absolutely necessary in many metallurgical processes.
If a reducing flame was to be obtained only a small portion of air was intro-
duced and plenty of gas, which reduces the temperature of the fusion chamber, the
superfluous gas unburned absorbing not only a great portion of the heat in the
chamber, but also in the hearth, and escaping without having done any service.
By the construction represented in the accompanying Drawings this inconvenience
has been obviated and the furnace rendered more efficacious when operating with a
reducing as well as with an oxidating flame for the highest temperature.
Figure I. is a plan of the said furnace partly in horizontal section on the line
GH, JK, LM, Figure II.; Figure II. is a longitudinal vertical section on the
line A, B; Figure III., a transverse vertical section on the line EF; and
Figure IV., a transverse vertical section on the line CD, of the same.
The combination of the different apparatus and the operation of the furnace are
as follows:-If the action of the flame must be absolutely reducing the gas is
introduced from the generator operating with air, and represented at a in Figure 1
of the Drawing, into the apparatus c through the conducting canal b. According
to the position of the valves it passes into the canal d or d¹.
Suppose the gas as indicated in the Drawing by the arrows passes through the
channel d and in the chamber e situated under the furnace, and by partition walls
divided into three compartments, so that the gas is forced to rise, and fall, and to
rise again, as indicated by the arrows in Figure II., in contact with the stones
forming gratework. Having passed through the three compartments of the
[Price 8d.1

page_text: chamber e the gas is introduced in the hearth m, where the objects are placed to
undergo the action of the reducing flame.
The gas escapes through the channel 1, which leads it to the upper part of the
first compartment of the chamber e where the combustion of the gas by the air
introduced takes place.
The air is supplied in the following way, that is to say :-The channel g intro-
duces the air compressed by a blower in the pipes of the reheating apparatus f;
the reheating apparatus is such as is often employed in high furnace works. The
air channel introduces the air in the upper part of the apparatus in the opposite
direction to the hot gases, and escapes at the lower part of the apparatus. On
escaping the air arrives at the valve u; in the case supposed this valve leads the
air on the side of the chamber e, while the gas is conducted to the chamber e.
From the channel h the air enters in the air chamber i wherein the valve vis
mounted. This valve is provided with slots corresponding with the apertures k, so
as to permit the entrance of the air into the chamber e. There the air meets the
gases arriving from the furnace through the conducting channel ", which causes its
combustion. The gases produced by the combustion then pass through the three
compartments of the chamber e¹, and communicate to the grate work placed therein
the greater part of their heat through the channel d, also provided with gratework
to the apparatus c, where they are compelled by the position of the valve to enter
the channel n discharging into the reheating apparatus. In the reheating
apparatus the last part of heat contained in the gases are used for heating the air.
In the reheating apparatus is mounted a chimney o, through which the gases escape
into the open air.
The air and gas having passed through the furnace and the chamber in one
direction in the manner indicated, by reversing the reversing valve of the valve u,
by shutting the obturator v¹, and opening the valve van opposite direction is
established for the air and gas, so that the gas arrives in the direction d, e, l, m, 1,
in the chamber e, and the air through u, h, i, v, k, in the said chamber. It is well
understood that in this case the combustion takes place in the upper part of the
chamber e.
Suppose the gas to be oxidized carbon and azote coming from the generator at a
very low temperature, for instance, 50° C., the channel C conducting the gas into
the apparatus a and valve, and therefrom through the channel d in the chamber e,
through the channel e on the hearth m, and through the canal to the room of
combustion in e¹. Suppose also that the whole apparatus, furnace, chambers,
channels have when completely dry a temperature of about 12° C., the gas after
having lost in its passage the greater part of its heat will arrive at c at a tempe-
rature of about 20° C; there it will burn by the affluent air, also of a low temperature.
The increase of temperature resulting from this combustion of the gas of 20° C. is
400° C.; after the combustion the gases will have 400 + 20: 420° Č. On passing
through the chambers they will communicate to the gratework in the chambers,
and also in the reheating apparatus to the air conducting pipes a part of their heat;
the gratework in e¹ and the reheating apparatus are thereby brought to an average
temperature of about 250° C., so that where the combustion takes place the stones
have about 400° C., and the gaseous products resulting from the combustion or
escaping at the upper part of the reheating apparatus will have still 60° C. Now
the air and the gas are directed in the opposite way.
-
Both the air in the reheating apparatus and the gas in the gratework of the
chamber e obtain a higher temperature, so that the gas on entering the furnace
through has about 100° C. After having lost perhaps one half of its heat on the
hearth it arrives at e with 50° C., and meets there the air heated at about 100° C.,
so the average temperature before the combustion of the gas is 70-75° C. The
increase of temperature of 400° C. resulting from the combustion gives a temper.
ature of 475° C. of the gaseous products. The gratework in e through which pass
the gases of the combustion will be heated to a much higher temperature than the
grate work in e¹ because the gases are much hotter. For the same reason the gases

page_text: will pass out of the reheating apparatus at a higher temperature, so causing the air
to be brought also to a higher teinperature. Suppose the grate work in e and the
reheating apparatus be brought to an average temperature of 300° C., the grate-
work in e will have at its upper part perhaps a temperature of 450° C., at the escape
of the reheating apparatus about 80° C. By reversing again the reversing apparatus
and the valve, the gas passing through the chamber e will obtain perhaps a tem-
perature of 150° C., will lose in its passage through the furnace perhaps 75° C., but
increase its temperature, and arrive at the other side in e' at 75° with an increase
of 251° C. to burn there.
The air will enter also at a higher temperature, the stones will obtain a higher
temperature, and also the reheating apparatus. In the next change the gas will
gain again 50° C., whereof 25° C. will be absorbed by the furnace; that is to say, a
continuous increase will be produced, 25° C. at each change; the temperature
in the furnace will be of 1000° C. after the 40th change, and of 200° C. after the 80th
change.
If the change takes place at every half hour there will be after 40 hours &
temperature in the furnace of 2000° C., which is sufficient for the reduction of iron-
stone of the oxide, oxidate of manganese, and for keeping steel in fusion.
The above figures indicating the degrees of temperature are only mentioned as
examples to show the results of the working.
It will be readily understood that in ail cases the gas remaining unburned serves
for the transferring of the heat from the grates of the brickwork to the proper
furnace, enters the furnace with a continuously increasing temperature, and thereby
communicates to it a continuous increase of heat.
If a neutral or oxidizing flame is to be obtained, the valve in the air
conducting channel is so placed as to cause the air, on its escaping from the
reheating apparatus, not to pass below, but enter through h,,, the funnel at tho
same side where the gas is introduced. The same results will then he obtained as
in the regenerative Siemens' furnace, but more favorably as the direction of affluent
air can be regulated by the position of the slots 2, thereby preventing the fusion
of the arch by the flame, as often occurs in the Siemens' furnaces.
It is possible to quickly obtain very high temperatures on the hearth with a
reducing flame on the other side. It is then only necessary on changing not to shut
completely the valve u, so as to permit the air to enter the two arms of the air con-
ducting channel and arrive at c and e'. In actuating the valve the distribution is
easily obtained. In this case as the gas enters at the side of the chamber e, the
valve u situated in the air conducting pipe is shut, so that the air cannot enter
the chamber e, but arrives on the hearth through h³, i², k³, a portion of the gas is
consumed, whilst the other portion of the gas burns at c.
The perforated obturators v, v³, v², v³, serve to prevent the entrance of the gas
from its chamber into the air chamber. They are provided with alots, through
which the gas when necessary arrives in the escape apertures k, k¹, k², 1, whence it
enters the chamber on the hearth.
The valves or obturators u² and u³ are so arranged that on opening entirely the
air conducting channel discharging into the chamber the branch to the hearth will
be shut completely, and vice versa. The Drawing shows as an example a " Siemens
Martin" furnace for the fusion of steel where this Invention is adapted; it can
however be used in all furnaces for heating iron, for reducing, calcining, oxidizing,
and fusing. In the Drawing the cut, the casting funnel moulds, and burning tablo
have been taken into consideration, because a furnace for the fusion of steel has been
taken as a model. If the furnace is to be used for the fusion with reduction, for
which this Invention is advantageously applicable, the cut and the casting funnel
are exposed to an atmosphere of the reducing gas operating in the furnace, and
thereby every danger of oxidation is prevented.
The advantages of the gas furnace above described are as follows:-
First. The heat of the products of combustion is more perfectly utilized than in
the regenerative Siemens' furnace,

page_text: Second. A reducing or oxidizing flame can be obtained on the hearth with
certainty.
Third. The reducing flame can be obtained without loss of gas, as in the Siemens'
furnace.
Fourth. By so placing the valve that one portion of the air acts at one side of
the hearth room, and the other at the other side in the chamber, the highest tem-
peratures can be produced without any danger of oxidizing. It must be supposed
that the gas heated to 2000° C. has been burned partly on the hearth, and it will
be readily understood that a high temperature can be quickly obtained.
Fifth. The construction of the furnace is so much simplified that there is only
one lower chamber at each side, and I dispense with the ordinary complicated con-
ducting channels for air and gas from the chambers.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Ludwig Haarmann in the Great Seal Patent Office on the 12th March
1877.
LUDWIG HAARMANN, Engineer, in the City of Hanover, Kingdom of Prussia,
Empire of Germany. "AN IMPROVED ARRANGEMENT OF A REGENERATIVE SIEMENS'
FURNACE."
In the construction of the Siemens' regenerative gas furnaces heretofore used it
was not possible to obtain on the hearth a flame merely reducing or oxidating, such
as is absolutely necessary in many metallurgical processes. If a reducing flame was
to be obtained only a small portion of air was introduced and plenty of gas, which
reduces the temperature of the fusion chamber, the superfluous gas unburned
absorbing not only a great portion of the heat in the chamber but also in the hearth,
and escaping without having done any service.
By the construction represented in the accompanying Drawings this inconvenience
has been obviated and the furnace rendered more efficacious when operating with a
reducing as well as with an oxydating flame for the highest temperatures.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a plan of the said furnace partly in horizontal section on the
line G H, JK, LM, Figure II.; Figure II. is a longitudinal vertical section on
the line AB, Figure 1; Figure III. is a transverse vertical section on the line EF;
and Figure IV. a transverse vertical section on the line CD, of the same.
The combination of the different apparatus and the operation of the furnace are
as follows: If the action of the flame must be absolutely reducing the gas is
introduced from the generator operating with under air and represented at a in the
plan of the Drawing into the apparatus c through the conducting canal b; according
to the position of the valves it passes into the canal d or d³.
Suppose the gas, as indicated in the Drawings by the arrows, passes through the
channel d and in the chamber e situated under the furnace, and by partition walls
divided into three compartments, so that the gas is forced to rise, to fall, and to rise
again, as indicated by the arrows in Figure II., and thereby to be as long and as
perfectly as possible in contact with the stones forming the gratework. For the
sake of clearness in the Drawings the gratework is only represented on one side.
Having passed through the three compartments of the chamber e the gas is
introduced in the hearth m, where the objects are placed to undergo the action of
the reducing flame.
The gas escapes through the channel 1, which leads it to the upper part of the
first compartment of the chamber e, where the combustion of the gas by the air
introduced takes place.
The air is supplied in the following manner, that is to say, the channel g

page_text: introduces the air compressed by a blower in the pipes of the reheating apparatus f.
The reheating apparatus is such as is often employed in high furnace works. The
air channel introduces the air in the upper part of the apparatus in the opposite
direction to the hot gases and escapes at the lower part of the apparatus. In
escaping the air arrives at the valve u; in the case supposed this valve leads the air
on the side of the chamber e while the gas is conducted to the chamber e. From
the channel h¹ the air enters in the air chamber i¹ wherein the valve v¹ is mounted;
this valve is provided with slots corresponding with the apertures k¹, so as to perimit
the entrance of the air into the chamber e; there the air meets the gases arriving
from the furnace through the conducting channel ", which causes its combustion.
The gases produced by the combustion then pass through the three compartments of
the chamber e and communicate to the grate work placed therein, the greater part
of their heat through the channel d, also provided with gratework, to the
apparatus c, where they are compelled by the position of the valve to enter the
channel n discharging into the reheating apparatus. In the reheating apparatus
the last part of heat contained in the gases is used for beating the air.
reheating apparatus is mounted a chimney o, through which the gases escape into
the open air.
In the
The air and gas having passed through the furnace and the chamber in one
direction in the manner indicated, by reversing the reversing valve c of the valve u,
by shutting the obturator v¹ and opening the valve van opposite direction is
established for the air and gas, so that the gas arrives in the direction d, e, l, m, 1,
in the chamber e and the air through u, h, i, v, k, in the said chamber. It is well
understood that in this case the combustion takes place in the upper part of the
chamber e.
Suppose the gas to be oxidized carbon and azote coming from the generator at a
very low temperature, for instance, 50 degrees C., the channel b¹ conducting the gas
into the apparatus a, valve c, and therefrom through the channel d in the chamber e,
through the channel on the hearth m, and through the canal to the room of com-
bustion in e¹. Suppose also that the whole apparatus, furnace, chambers, channels, have
when completely dry a temperature of about 12 degrees C., the gas after having lost
in its passage the greater part of its heat will arrive at c at a temperature of about
20 degrees C.; there it will burn by the affluent air, also of a low temperature. The
increase of temperature resulting from this combustion of the gas of 20 degrees C.
is 400° C.; after the combustion the gases will have 400+20=420° C. On
passing through the chambers they will communicate to the gratework in the
chambers and also in the reheating apparatus to the air conducting pipes a part of
their heat; the gratework in e¹ and the reheating apparatus are thereby brought to
an average temperature of about 250 degrees C., so that where the combustion takes
place the stones have about 400 degrees C., and the gaseous products resulting from
the combustion or escaping at the upper part of the reheating apparatus will have
still 60 degrees C. Now the air and the gas are directed in the opposite way.
Both the air in the reheating apparatus, and the gas in the gratework of the
chamber e obtain a higher temperature, so that the gas on entering the furnace
through has about 100 degrees C. After having lost perhaps one-half of its heat
on the hearth it arrives at e with 50 degrees C., and meets there the air heated at
about 100 degrees C., so the average temperature before the combustion of the gas
is 70-75 degrees C. The increase of temperature of 400 degrees C. resulting from
the combustion gives a temperature of 475 degrees C. of the gaseous products. The
gratework in e through which pass the gases of the combustion will be heated to a
much higher temperature than the gratework in e¹, because the gases are much
hotter. For the same reason the gases will pass out of the reheating apparatus at
a higher temperature, so causing the air to be brought also to a higher temperature.
Suppose the grate work in e and the reheating apparatus be brought to an average
temperature of 300 degrees C., the gratework in e will have at its upper part
perbaps a temperature of 450 degrees C., at the escape of the reheating apparatus
about 80 degrees C. By reversing again the reversing apparatus and the valve the

page_text: +
gas passing through the chamber e will obtain perhaps a temperature of 150 degrees C.,
will lose in its passage through the furnace perhaps 75 degrees C., but increase its
temperature and arrive at the other side in e¹ at 75 with an increase of 251 degrees C.
to burn there.
The air will enter also at a higher temperature, the stones will obtain a higher
temperature, and also the reheating apparatus. In the next change the gas
will gain again 50 degrees C., whereof 25 degrees C. will be absorbed by the
furnace; that is to say, a continuous increase will be produced, 25 degrees C. at each
change; the temperature in the furnace will be of 1000 degrees C. after the fortieth
change, and of 200 degrees C. after the 80th change.
If the change takes place at every half-hour there will be after 40 hours &
temperature in the furnace of 2000 degrees C., which is sufficient for the reduction of
ironstone of the oxide, oxydule of manganese, and for keeping steel in fusion.
In the above description the heat becoming free by the combustion has been taken
into consideration as being only absorbed by the products of the combustion whilst
it is also communicated to the gratework of the generators.
The above Figures indicating the degrees of temperature are only mentioned as
examples to show the results of the working.
It will be readily understood that in all cases the gas remaining unburned serves
for the transferring of the heat from the grates of the brick work to the proper
furnace, enters the furnace with a continuously increasing temperature, and thereby
communicates to it a continuous increase of heat. Theoretically the gas can be
brought to an infinitely high temperature; the temperature that can be obtained in
practice may be proved by experiments. It is certain in all cases that in the
"Whitwell" apparatus the air has been heated to more than 800 degrees C.
Considering that the said "Whitwell" apparatus is heated only by gas burned by
cold air, it will be obvious that in this improved apparatus a much higher temperature
can be obtained. The said apparatus has been above described on the supposition
that a reducing flaine is to be produced. If on the contrary a neutral or oxydizing
flame is to be obtained the valve u¹ in the air conducting channel is so placed as to
cause the air on its escaping from the reheating apparatus not to pass below but
enter through h², 2, k², the funnel at the same side where the gas is introduced. The
same results will then be obtained as in the regenerative "Sienens"" furnace, but
more favourably, as the direction of the affluent air can be regulated by the position of
the slots k², thereby preventing the fusion of the arch by the flame, as often occurs
in the "Siemens'" furnaces.
It is possible to quickly obtain very bigh temperatures on the hearth with a
reducing flame on the other side. It is then only necessary on changing not to shut
completely the valve u, so as to permit the air to enter the two arms of the air
conducting channel and arrive at e and e¹. In actuating the valve the distribution is
easily obtained. In this case as the gas enters at the side of the chamber e, the
valve u situated in the air conducting pipe is shut, so that the air cannot enter the
chamber e but arrives on the hearth through h,, ; a portion of the gas is
consumed whilst the other portion of the gas burns at e.
The perforated obturators v, vl, ², ³, serve to prevent the entrance of the gas
from its chamber into the air chamber. They are provided with slots through
which the gas, when necessary, arrives in the escape apertures k, k, k, k³, whence
it enters the chamber on the hearth.
The valves or obturators u¹ and u² are so arranged that on opening entirely the
air conducting channel discharging into the chamber the branch to the hearth will
be shut completely, and vice versa. The Drawings shew as an example a "Siemens
Martin" furnace for the fusion of steel where this Invention is adapted; it can
however be used in all furnaces for heating iron, for reducing, calcining, oxidising,
and fusing. In the Drawings the cut, the casting funnel, moulds, and burning
table have been taken into consideration, because a furnace for the fusion of steel
has been taken as a model. If the furnace is to be used for the fusion with reduction,
for which this Invention is advantageously applicable, the cut and the casting

page_text: funnel are exposed to an atmosphere of the reducing gas operating in the furnace,
and thereby every danger of oxidation is prevented.
The construction of this Invention may be modified according to the purpose to
which it is to be applied and to the local circumstances attending its use. The dimen-
sions may be varied to any required extent.
The gas and the air can be forced by a fan or blower. The dimensions of the
blower and the pressure of the air and of the gas depend also upon local circum-
stances and upon the purpose for which the said Invention is to be used.
The advantages of the gas furnace above described are as follows:-
First. The heat of the products of combustion is more perfectly utilized than in
the regenerative "Siemens" " furnace.
Second. A reducing or oxidising flame can be obtained on the hearth with
certainty.
Third. The reducing flame can be obtained without loss of gas, as in the
"Siemens" furnace.
Fourth. By so placing the valve that one portion of the air acts at one side of the
hearth room, and the other at the other side in the chamber, the highest temperatures
can be produced without any danger of oxidising. It must be supposed that the
gas heated to 2000 degrees C. has been burned partly on the hearth, and it will be
readily understood that a high temperature can be quickly obtained.
Fifth. The construction of the furnace is so much simplified that there is only one
lower chamber at each side, and I dispense with the ordinary complicated conducting
channels for air and gas from the chambers.
Having thus fully described my said Invention and the manner of performing the
same, I wish it understood that I claim, a regenerative furnace of the class above
described, and in which is embodied the arrangement whereby the air for the com-
bustion introduced under pressure is not heated in chambers below the furnace as
in theordinary "Siemens" " regenerative furnace but in separate reheating apparatus,
thereby permitting the air to be easily conducted from this reheating apparatus to
all parts of the furnace where it is required, and in which the reheating apparatus
is heated by the waste gases of the furnace or independently of the same, as above
set forth.
In witness whereof, I, the said Ludwig Haarmann, have hereunto set my hand
and seal, this Sixth day of March, in the year of our Lord One thousand
eight hundred and seventy-seven.
LUDWIG HAARMANN. (L.S.)