IMPROVEMENTS IN AND RELATING TO HOT-BLAST APPARATUS FOR USE IN METALLURGICAL OPERATIONS
Year: 1881

page_text: LETTERS PATENT to Henry Harris Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of "IMPROVEMENTS IN AND RELATING TO HOT-BLAST APPARATUS FOR USE
IN METALLURGICAL OPERATIONS." A communication from abroad by John
Coover Long, of Richmond Furnace, Pennsylvania, United States of America,
Mining Engineer and Doctor of Medicine.
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at
the Office of the Commissioners of Patents on the 18th October 1881.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO HOT-
BLAST APPARATUS FOR USE IN METALLURGICAL OPERATIONS." [A communication
from abroad by John Coover Long, of Richmond Furnace, Pennsylvania, United
States of America, Mining Engineer and Doctor of Medicine.]
This Invention relates to improvements in regenerative hot blast apparatus for
heating a blast of air, gases, or vapor, to be supplied to metallurgical furnaces for
intensifying the action therein.
Heretofore it has been customary to heat regenerative hot blast apparatus by
burning therein gas having a temperature equal to that which it has when leaving
the blast furnace or other source of supply, less that lost during its passage to the
hot blast apparatus. This temperature, in the case of the waste gases of the blast
furnace, is about 300° or 400°, as it leaves the furnace, less the loss of transmission.
The air used for combustion is drawn into the apparatus by means of the draught
of a very bigh chimney, and is used at the temperature of the atmosphere, except
in one case, in which it is claimed to be heated by passing through passages or
channels in the partition walls of the apparatus.
Now the above methods are objectionable because the temperature or intensity
of the heat of the blast is limited, on account of using the combustible gas at so
low a temperature, and burning it with air drawn in by a tall chimney, by which
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page_text: means no intense combustion of the gas or proper distribution of the products of
combustion can be produced. Further, on account of the method of heating the air
for combustion, it is evident that it can attain no very great temperature, as the
passage in which it is heated cannot be made sufficiently large. The quantity of
air necessary for combustion bears quite a large ratio to the quantity of blast that
an oven can heat, and it is manifest that the surfaces of the passages do not bear a
similar ratio to the surfaces of the flues of the oven.
The object of this Invention is to provide a regenerative hot blast apparatus, by
means of which a blast of air, gases, or vapors may be obtained, whose temperature
is only limited by the resistance of the refractory material composing the apparatus,
thus greatly facilitating and economizing metallurgical operations now employed,
and rendering useful some heretofore considered impracticable ones.
In most
metallurgical operations it is a great intensity of heat or temperature that is
desired, for a metal may be exposed to any quantity of heat without fusing,
provided the temperature be below its fusing point; while on the contrary a short
exposure to a temperature but slightly above its melting point will fuse it, although
in the latter case it is exposed to a much smaller quantity of heat, but that of
greater intensity, hence greatly economizing fuel and facilitating the operation.
And, as in the blast furnace, the quantity of fuel over and above that necessary to
reduce the ore and carbonize the metal is used mainly for fusing the metal and
slag, it follows that the more intensely the blast is heated the, less fuel it will
be necessary to burn in the hearth of the furnace, and as a blast can be produced
by my apparatus, whose temperature is only limited by the resistance of the
refractory materials of the ovens, by its use a blast furnace can be worked nearer
the theoretical minimum of fuel than heretofore, and as a consequence of the
decrease in the fuel, the relative necessary air supply is also reduced and the
working capacity of the furnace increased, and owing to the greater space for
charges other than fuel, thus materially reducing the cost of production. By using
a very intensely heated blast greater control of the furnace is obtained, and more
refractory ores and fluxes can be used, thus making valuable heretofore useless
materials.
To this end my Invention consists partly in the combination with the peculiarly
constructed ovens in which the blast of air, gases, or vapors, are heated prior to
passing to the furnace of similar supplementary ovens or heaters for heating the
combustible gas, which is subsequently burned in both the blast ovens and gas
heater for the purpose of intensely heating them, as is more fully explained herein-
after; and it also consists in the connections by which the gas heaters are connected
to the ovens and with each other, whereby the highly heated combustible gas may
be introduced into the oven, or gas heated to be burned therein; and it further
⚫ consists in introducing into the ovens and gas heaters of a forced blast of highly
heated air from the hot blast main or parts in free communication with it, thus
burning the combustible gases therein by a forced hot blast to intensify the
combustion thereof, and produce an equable distribution of the hot products of
combustion and a more equal heating of the ovens and heaters, and at the same
time decreasing the amount of draught necessary to be produced by the chimney;
and it also consists of the air connections employed for this purpose.
In carrying the said Invention into practice, when a continuous blast is desired,
at least two ovens are employed for heating the blast supplied to the furnace. In
connection with the ovens as above, two or more gas heaters are used, and in a
similar manner to the ovens as above. In the following description but two ovens
for heating the blast are combined with two gas heaters for heating the
combustible gas.
The ovens for heating the blast are rectangular in form, and constructed of fire-
brick or other suitable refractory materials, and whose walls are supported by
circular or elliptical segmental walls of ordinary brickwork and encased in sheet
iron, or the space between the oven and the sheet iron casing may be filled with
cinders, loam, or broken bricks, or the like. The sheet iron casing is suitably

page_text: strengthened at the angles to resist the strain put upon it by the pressure of the
blast and the expansion of the oven. The roof is also covered with sheet iron put
on in strips corresponding with the width of the roofs of the flues, and having up
turned flange-like edges bolted together, and held down in place by girders passing
over the middle of each flue, and fastened at each end to the side casing of the
oven.
The interior of each oven is divided into two parts, viz., a combustion chamber
and a regenerator, by a wall, which extends from the bottom to near the top, only
allowing sufficient room for a horizontal flue. The lowest part of the combustion
chamber is contracted by the walls, which are run up square to the level of a
perforated air cylinder and blocks, and thence they rapidly taper off for the
purpose of producing a more perfect combustion of the gas and for increasing the
draught by means of the diverging jets of air from the cylinders and blocks, as
well as evenly distributing the flame and gaseous products of combustion to the
several independent compartments of the ovens hereinafter mentioned. The air
cylinder is placed in the combustion chamber, so that it shall be midway between
the air blocks at the angle of the side walls in order to divide the combustible gas
equally. The cylinder is perforated by a number of circular holes so arranged
that no two adjacent ones shall be in the same vertical plane, thus, as it were,
breaking joints, so that the jets of air issuing therefrom shall have different vertical
angles, the lower ones being horizontal, or nearly so, the others at different angles,
so as to equally distribute the flame throughout the combustion chamber. The air
blocks are placed at the angles of the walls and are provided with holes arranged
in a similar manner to those in the cylinder, but so that the jets issuing from them
shall not strike those from the said cylinder, but shall pass between or interlace
with them. Thus having the ascending combustible gas divided by the cylinder,
and each current passing between two series of air jets, by the lower of which the
gas is mixed with air and then burned by the upper ones, thus having it consumed
under circumstances the most favorable for the production of a most intense heat.
The cylinder and air blocks communicate with a hot air main or parts in free
communication with it by means of pipes having regulating valves, which, when
once properly set, always remain open during the operation of the oven, both when
it is heating the blast and when it is burning gas. The air blocks lying on the
adjacent sides of the ovens may be connected directly by a pipe having a valve.
The lower part of the combustion chamber is provided with an opening for the hot
blast and a hot gas connection, and for a cold gas connection, as well as an opening
for the removal of dust.
The upper part of the combustion chamber is provided with a series of flues
communicating with a regenerator, and formed by roof-supporting-partition walls,
which walls extend from the front to the back, and from the top to the bottom of
the ovens, except in the combustion chamber, in which they extend only to the top
of the sloping walls. The oven is thus divided into several independent compart-
ments, which in the regenerator are divided by walls into flues arranged in sets,
forming a decreasing series from the combustion chamber, and the spaces at the
top and at the bottoms are formed by having the walls to neither reach the top or
bottom, except in that forming the last flue of the first set, which extends to the
top, and that forming the last flue of the second set, which extends to the bottom,
thus for example having four flues in the first set, three in the second, and two in
the third set, and forming a decreasing series from the combustion chamber, or an
increasing series from the cold end. And as the gaseous products of combustion
contract while cooling the surfaces over which they pass, and impart their heat as
well as the capacity of the passages, and absorbing materials decrease in proportion
and conversely as the blast expands as it is heated, the capacity of the passages
and heat imparting materials and surface over which it passes increases, thus in
either case maintaining a uniform velocity, and having the absorbing and radiating
surfaces and capacity of the passages or sets of flues and quantity of materials
proportioned to the volume of the products of combustion or blast passing through

page_text: each part of the oven, and in addition thereto the products of combustion as well
as the blast are by means of the several independent compartments containing the
above described series of flues, compelled to pass through the oven in independent
currents, thus obtaining a more equable heating of the oven and distribution of the
blast to be heated, and consequently very greatly increasing the efficiency of the
apparatus.
There is a small transverse channel in the inverted circular bottom of the
chambers extending through the oven and closed by suitable doors or means at the
sides of the oven for the purpose of removing the dust. Similar opening is made
in the combustion chamber.
The lower parts of each last set of flues in the several independent compartments
communicate with each other, and also communicate with the chimney by means
of openings in the walls and connections and pipe which is provided with a valve,
by which means communication can be cut off or established at will. They also
communicate with the cold blast supply pipe, by which communication can be
established or cut off at will. The ovens or combustion chambers communicate
with the hot gas supply main by means of a pipe, provided with a valve for the
purpose of receiving hot gas for combustion and with the hot blast main by means
of the said pipe and a vertical pipe, and provided with a valve and a branch for
the purpose of carrying the hot blast from the oven to the hot blast main.
All of the pipes or connections and mains are lined with fire brick, with the
exception of the cold blast supply pipe.
The gas heaters are constructed similarly to the ovens internally, but may be made
smaller by decreasing the number of compartments or the number of flues, or both.
The combustion chamber may be constructed like those of the ovens, or they may
be made with either the air cylinders or air blocks alone. In any case their
connection to the hot air main for receiving hot air for combustion is made by a
pipe or pipes having a valve or valves by which communication can be established
or cut-off at will. The gas heaters deliver the gas which they have heated into the
hot gas main through the hot gas connection pipe provided with the valve,
by which communication can be established or cut off. The gas heaters
also communicate with the main by means of pipes having valves by which the
ovens can be supplied with hot gas for combustion when they are being heated.
The hot gas for combustion may be supplied directly from one heater to the other
by means of a pipe having a regulating valve extending from the combustion
chamber of one gas heater to that of the other. This valve in this case, after being
properly set, always remains open. There are combustion chambers also connected
with the cold air supply main by means of another pipe having a valve.
The gas heaters are connected with the chimney by means of a connection, a valve,
horizontal pipe having a valve, and connecting with a vertical pipe and horizontal
pipe to chimney. They are also connected with the cold gas supply main for the
purpose of receiving the gas to be heated by means of a pipe, valve, and
connection.
A cast iron slide valve is used in connection with my apparatus. The valve is a
wedge-shaped gate, having a rectangular head and stem. The valve, and head, and
stem are formed in a manner similar to that of the preceding valve, only that the
pipe after descending to the bottom of the valve is bent so to be as near the
surface of the valve as possible, and at the same time to be constantly ascending
toward the stem up which it goes and is connected to water and waste pipes as in
the former valve. It is also provided with a rack and counteracting counter
balance pulley, and is moved in manner similar to the seat valve, only there is but
one pulley instead of two. The valve chest is formed in two parts, both made of
cast iron and cooled by water passing through continuous wrought iron pipes. The
lower part is made wedge-shaped to correspond with the shape of the valve, and is
planed out on the face sides to fit accurately and air-tight the planed faces of the
valve. It is cooled by the two sets of pipes, one for each face of the seat, which
pass directly in and across the opposite side and then down to near the bottom, and

page_text: then up and around the seat of the valve, and then up the side of entrance, and
then across and out at opposite side into the waste pipe. The upper part is made
somewhat smaller than the lower part, to which it is bolted so as to fit the square
head of the valve, so that the instant the valve is moved upward it leaves its
sloping seat and is supported by its head moving against the sides of the upper
part; thus I very much decrease the wear on the valve surfaces. It is cooled by a
spiral pipe attached to proper waste and water pipes. The stuffing box is made
similar to that in the seat valve.
In practice, at least two gas heaters are used in combination with at least two
ovens for heating the blast, but in cases where the apparatus is used for beating
anything but air it will be necessary to use a set of two supplementary ovens to
heat the air for combustion, and having an additional hot air main and connections
if it is desired to have hot air for burning the combustible gas.
By properly proportioning the quantity of blast to be heated to the size of the
ovens, and heaters, and quantity of gas to be heated, and regulating the intervals
between reversals, any temperature of blast can be maintained provided it be not
beyond the resistance of the material; or the temperature may be varied by the
operator as demanded by the exigencies of the metallurgical operations.
The gas heaters are also arranged so that they can be supplied with cold gas for
combustion from the cold gas main by means of a branch or pipe, herein before
mentioned having a valve. In this case the valve on the connecting pipe is closed,
and the method of operating is the same as when the gas for combustion was
obtained from the hot gas main by means of the valve, excepting that one valve is
used in place of another. If it is desired, a mixture of hot and cold gas can be
used by having the valve partially opened.
The ovens are also so arranged that they can burn cold gas in connection with
hot air. The cold gas is supplied from the cold gas main by a branch provided
with a valve, and in the reversals this valve is substituted for the hot gas valve,
but otherwise it is the same. They can also be run on a mixture of hot and
cold gas, and in this case it is necessary to use both of the valves to admit the
gas.
When using cold gas the gas heating part of the apparatus may be done away
with or held in reserve, in case an intensely hot blast is desired, as when the blast
furnace is working cold and badly.
According to another form of my Invention I provide a regenerative hot blast
oven, which can be used either for heating the blast or for treating the combustible
gas burned in the apparatus, so that it may be substituted for either a special blast
oven or a special gas heater, or both, in order to heat the combustible gas prior to
its being burned in the apparatus, whereby a more intense heat may be developed
therein than when the apparatus is heated by the combustion of gas which has not
been heated after leaving its source, and which is so arranged with suitable
connections that it can be used either for heating the blast, or for heating the
combustible gas by being heated for each object specially, or it can be used as a gas
heater without being specially heated therefor, by making available the large
quantity of heat yet in the oven when used to heat the blast after it has lost that
portion of its heat which is effective in heating the blast to the required
temperature, and which combined blast oven and gas heater may be substituted
for either the special gas heaters or blast ovens, or for both, as aforesaid, so that
when used as a gas heater it can in case of failure or repair of the blast ovens be
used for heating the blast, thus furnishing a duplicate set of blast ovens without
increasing the cost of the plant, and at the same time avoiding the danger incident
to a failure of the hot blast by the giving out of the special blast ovens, and in
addition thereto the object is to furnish a means of altering the regenerative hot
blast apparatus now in use to my improved system, either by adding thereto one
or more combined blast ovens and gas heaters directly connected thereto so as to
form couples, and consisting of an oven used as a gas heater, and an oven used as a
blast oven, as hereinafter described, or all may be connected to a common hot gas

page_text: main, and in both cases adding to the other ovens the necessary hot and cold gas
and air connections, so that any or all may be used as blast ovens or gas heaters
as desired. Or a plant consisting of four blast ovens may be altered to my system
when the ovens are arranged along a common cold gas supply main having no
other branches, by putting in the main a valve between the ovens and blast
furnace or other source of gas supply, and then using the portion thus cut off as a
hot gas main; or in case each pair of valves has a common gas supply main without
other branches, then by cutting it off, as above described, a hot gas main is formed
leading from one oven to the other, and the pair is worked as a couple; in both
cases the necessary additional hot and cold gas and air connections are made so
that any oven may be used as a gas heater or blast oven, as desired.
In the case of a plant consisting of three ovens, it may, owing to the fact that
the combustible gas necessary to heat the apparatus has a much smaller volume
and less velocity and greater heat absorbing power than the blast, while the
specific heat is about the same, in both cases be altered to my improved system
without increasing the number of ovens, by altering them into combined blast
ovens and gas heaters by adding to the ovens the necessary cold gas main and
connections at the cool end in order to supply the gas to be heated, and at the hot
end a hot gas main connecting all of the ovens ; or in case the ovens have a common
gas supply main, thereby cutting it off by a valve between the ovens and blast
furnace or other source of gas supply, a hot gas main is formed, and using the
ordinary gas connections with the ovens for the passage of the heated gas. If it is
desired to burn the heated gas with hot air, then the necessary connections must
be made as hereinafter described, but if cold air is used for combustion then the
ordinary air connections can be used.
A plant of three blast ovens may also be altered by adding one of the combined
ovens and gas heaters, and the necessary blast and gas and air connections to the
other ovens, and cutting off the gas supply main as above described.
The object is also to provide a means of heating a mixed blast of air and vapor,
and at the same time furnish pure highly heated atmospheric air for combustion
in the ovens and gas heaters; also to provide for expansion and contraction and
for the equal heating of the oven and equal distribution of the gas or blast to be
heated.
In this Specification when speaking of cold and cool gas I mean gas at the
temperature it has after leaving the blast furnace or other source of supply, less
the temperature lost in transmission to the apparatus in which it is burned,
that is, combustible gas which has not been heated after leaving the apparatus in
which it was produced, and prior to its introduction into the apparatus in which it
is burned.
The tendency of modern blast furnace engineering is to reduce the temperature
of the waste gases from the blast furnace as low as possible, and is a result of the
widening of the blast furnace throat, as now done in the more modern blast
furnaces, in order to save fuel and improve the working of the furnace. In fact
one very high authority says that the temperature of the waste gases of a blast
furnace should not exceed 212° Fahrenheit, hence the necessity of having a means
of heating the gas so as to be able to command an intensely heated blast.
This part of my said Invention consists in the regenerative hot blast oven
having cold blast or air, and cold gas and chimney connections at the cool or
chimney end, and having at the hot or combustion chamber end hot blast and hot
gas delivery connections, as well as the hot and cold gas and hot and cold air con-
nections for supplying the necessary hot or cold gas to heat the oven by being
burned therein, by hot or cold air or by a mixture of hot or cold air, and whose
walls are so constructed as to provide for expansion and contraction of the several
walls, and whose roof is constructed as described.
It also consists in the horizontal flues, and the several connecting pipes and flues
or distributing mains at the cool end, whereby the gas or blast to be heated is
equally distributed, and of the flues, and pipes, and mains, and valves at the hot

page_text: end, whereby the combustible gas to be burned therein is equally distributed. It
also consists in the combustion chamber, divided into single or double compart-
ments by longitudinal walls extending from the roof, and to or near the bottom,
and having the air blocks or cylinders extending through the casing and into the
wall separating the combustion chamber and regenerator.
It also consists in the combination of the pipes and valves by which hot air is
supplied for combustion in the ovens or gas heaters, independent of the hot blast
main.
It further consists in the combination of one or more of the above described
ovens, used either as blast ovens or gas heaters, with one or more ordinary
regenerative or above described ovens, and as blast ovens.
It further consists in the combination of two or more combined ovens and gas
heaters, which are used successively for heating the combustible gas.
It further consists in the combination, with two or more ordinary regenerative
hot blast ovens, of the necessary hot and cold gas mains and connections by which
they may be used as blast ovens and gas heaters, either successively or in couples,
all essentially as hereinafter more particularly described.
The combined oven and gas heater is constructed of ordinary fire brick, or of
similarly shaped blocks of fire-brick or other refractory materials, and whose
dimensions vary with the temperature of the blast desired, so that all of the
material in the bricks or blocks may be useful in storing up and giving out heat,
for with different temperatures the depth to which the effective heat penetrates
and is given off varies. It is rectangular in form and is supported by curved
segmental walls of common or red brick, sand, slag, or the like, and incased in
sheet iron; or it may be made without the supporting walls with a rectangular
casing of sheet iron properly supported by outside girders or bracing; or the sheets
may be put on horizontally in strips whose length is equal to the width of the
several sides of the oven, and with their edges upturned flange like and fastened,
thus providing for lateral pressure. It is divided into two parts, the regenerator
and the combustion chamber, by a wall which extends from the bottom to near the
top, but allowing space for horizontal flues, and from side to side. It is also divided
into several independent compartments, either double or single, by means of roof
supporting walls, which extend from front to rear, and from the roof to the bottom,
except the regenerator part of those in the middle of the double compartments
which rest on arches forming the horizontal flues, and in the combustion chamber
in which those forming the double compartments extend either to below the
connection or to the top of the horizontal flue. They may extend to the bottom,
in which case each compartment would have a passage for removing the dust.
The walls in the middle of the double compartments may extend to between air
blocks or cylinders, and a connection for the passage of blast and gas, or they may
be cut off above the air cylinders or blocks; but in this case the air cylinders or
blocks are supported by walls to prevent sagging from the effects of heat.
The combustion chamber may be constructed with the walls in the middle of the
compartments single by extending all of the walls to the top of the flue, and each
compartment is provided with a connection. In order that there may more
certainly be an equal distribution of the combustible gas and the heated products
of combustion, the mouths of the connections are placed in the middle of each of
the compartments, either double or single. The air for combustion is introduced
through the perforated blocks or cylinders, placed either in the middle walls of the
compartments, or in the walls which form the sides of the single or double com-
partments.
The air cylinders or blocks extend through and even with the casing, and into
the wall, so that in case of repair they may readily be replaced from the outside of
the oven by removing the connecting pipes and connections. The air blocks or
cylinders may be made of fire clay or brick, metal, or other refractory material,
and if necessary may be cooled by causing a current of air or water to flow through
a pipe which may be embedded therein. The air cylinders or blocks are connected

page_text: by pipes having regulating valves to a pipe having a valve. This pipe connects
with another pipe communicating with the combustion chamber and having a
valve which may be made in the form of a check valve by having a suitably sized
seat valve so balanced as to be automatic, so as to prevent any back flow of air
when the oven is being heated, or is heating gas, but when the oven is heated the
blast opens automatically to allow the air necessary for combustion in the other
ovens to flow into the pipe, and thence by another pipe which connects it to the
similar pipes of the ovens.
If in all of the compartments except that next the cold blast entrance a blast of
steam or vapor be introduced in the connections, together with the cold air
introduced by the cold blast connection, then in all of the compartments there will
be a mixed blast, excepting the first, in which it will be of pure atmospheric air,
and this will by one connection be furnished for combustion, while a mixed hot
blast will be supplied to the furnace.
This pipe is also connected to the cold air main by a pipe having a valve, by
which means cold air may be supplied for combustion.
The dust may be removed from the combustion chamber through openings
which may also be used for firing the gas. The dust in the regenerator is removed
through other openings. The several compartments of the combustion chamber are
also provided with connections to a distributing main connected to dividing pipes,
which enter the main midway between the connections, so as to equally distribute
the combustible gas burned in the oven. The main may be formed outside of the
oven, when the connections will be horizontal, or the main may be formed in the
bottom of the combustion chamber by arching it over and making the vertical
connections to the several compartments. The outside connections will be by the
dividing pipe entering the oven, and main thus formed midway between the
connections. The dividing pipes are connected to the opposite oven by a pipe
having a valve either directly, or by means of similar dividing pipes, and
distributing main. The connecting pipe is connected to the hot blast main by
means of a vertical pipe, a valve, and branches. The opposite oven is connected
similarly to the hot blast main by a connection.
In the case of a plant of four ovens connected directly with opposite ones, thus
forming two couples, in each of which one oven is used as a gas heater while the
other is used as a blast oven, the connecting pipe connecting each couple is
connected with the corresponding pipe of the other couple by a pipe in free
communication therewith, having a valve by means of which hot gas may be
supplied from one oven used as a gas heater by opening the valve to pass the
proper quantity of gas and then leaving them open.
The connecting pipe is also connected to the source of cold gas supply by a valve
and main, by means of which cold gas may be supplied to the ovens or gas heaters
for combustion. The main may be used as a hot gas main by placing a valve in it
between the ovens and source of cold gas supply, and may be common to the
opposite ovens or gas heaters and connected to each by connections having valves.
This construction will admit of three ovens in a plant of four ovens being used, or
will give the advantages of having gas heaters in a plant of three combined ovens
and gas heaters. In case of the three regenerative hot blast ovens in the apparatus
now generally used, they may be altered to my improved system by adding the
necessary hot air connections for supplying the air necessary for combustion if it is
desired to burn the gas by means of a blast of hot air; or the ordinary air con-
nections may be used by placing a valve in the cold gas supply main, thus cutting
off communication with the furnace or other source of cold gas supply and forming
a hot gas main of the portion thus cut off. The present gas supply connection thus
serves for the passage of the heated gas into and out of the oven, and then add a
cold gas main and connections at the cool ends in order to supply the gas to be
heated in the apparatus. The above construction of the main will allow of the
apparatus being extended, as in case of four ovens and gas heaters, with a minimum
cost by additional ovens to the common main.

page_text: The regenerator is composed of walls forming vertical flues. Part of the walls
extend from the horizontal flues high enough to allow sufficient space for a
horizontal flue. Flues are arranged in one set so that the products of combustion
and gas or blast to be heated pass through the regenerator in but one direction,
that is, the former passing down while the latter pass up, thus decreasing the
friction. The roof supporting walls extend from the bottom to the roof, except in
the double compartments, in which they commence at the top of the arches
supporting them. The horizontal flues are either single or double; in the latter
case they are formed by arches carrying the walls of the double compartments. In
either case they have connections placed in the middle of the compartments for the
passage of the blast or gas to be heated as well as the products of combustion.
These connections connect with the distributing main having cold blast connection
and valve and chimney connection, and communicating with the cold gas supply
main by dividing pipes having a valve. These pipes are so placed as to be midway
between the connections which open into the middle of the compartments, so as to
equally distribute the gas to be heated. The distributing main and connections
also serve to equally distribute the blast to be heated. If the flues are arranged
in a certain manner, then the distributing main may be formed in the lower part
of the last set of flues by arching it over and making the main thus formed
continuous, as in the combustion chamber, by removing parts of the walls and
making vertical openings corresponding to the connection and opening into the
middle of the compartments. The connection of the cold gas main will then be by
the dividing pipes having a valve and entering the oven and distributing main
thus formed midway between the openings which may be made into each compart-
ment separately or may open into two jointly. The chimney and cold blast
communications may then be made directly to the oven and opening into the
distributing main thus formed. A vapor pipe having a valve has branches
excepting the one next the cold blast connection and into which they discharge
the steam or vapor. In case of forming the distributing main in oven, then the
branches open into the compartments above the flue if it is desired to heat a mixed
blast.
The roof is formed of a number of rectangular blocks and wedge-shaped blocks
of fire brick or other refractory material, and whose length equals the distance
between the centres of the roof supporting walls upon which they rest. The
wedge-shaped blocks are placed in those parts which are moved when access is
desired.
The roof blocks are covered with strips of sheet iron whose width equals the
length of the blocks, and having upturned flange-like edges which are bolted
together and held in place by guides placed transversely upon the flanges and
fastened to the outside casing.
The strips extend only over each portion, either that over the wedge-shaped
blocks and which is removed when access is desired, as in cleaning, or over that
formed by the rectangular blocks. The strips covering the wedge-shaped blocks
may slightly overlap the strips covering the rectangular blocks and to which they
are bolted, and may, if necessary, be held down by girders; or the strips covering
the wedge-shaped blocks may meet the strips over the rectangular blocks with
upturned flange-edges and bolted together. In case access is desired for cleaning
the girders if used the sheet iron strips and wedge-shaped blocks under them only
may be removed.
The several walls of the oven and gas heater are constructed of ordinary fire-
brick or similar rectangular blocks of fire brick or other refractory materials whose
dimensions vary with the temperature of the blast desired and the temperature to
which they are exposed, so that in case of the hotter blast they may be made
larger, as the depth to which the effective heat is absorbed and subsequently given
out increases with the temperature. The bricks or blocks are laid diagonally in
reverse directions in the adjacent walls or courses in the same horizontal planes
and in the adjacent courses in the same vertical planes, and they are laid on edge

page_text: or flat, as above described. The walls may also be made by having the bricks or
blocks placed on end and overlapping diagonally to different distances. The bond
is formed by having a horizontal binding brick extending from one wall to the
other, and which is itself held in place and bonded by vertical bonding bricks
placed at each side and alternate ends of the horizontal bonding bricks. The
vertical bonding bricks extend from the middle of one horizontal bonding brick
across the next and to the middle of the third, and in addition the vertical bonding
bricks break joints. The last named bonding bricks may also be placed hori-
zontally. The walls may also be bonded horizontally by a bond brick extending
from the middle of one wall to the middle of the horizontal bond brick.
The walls may be made by laying the bricks flat and diagonally and in reverse
directions, and bonded by a single bond brick and by a part of another brick and
a whole brick extending into the side wall; the next bond formed in this manner
by a whole brick, and part is so arranged that the whole brick shall extend into
the other wall. This construction of the walls is continued until they reach the
top of the flues, when the walls are constructed by laying the bricks diagonally
and in reverse courses as the walls were constructed until they reach their proper
height. By having the bricks laid diagonally and in reverse courses and bonded,
as described, the effects of expansion and contraction are effectively provided
against, which is a matter of the greatest importance in regenerative hot blast
ovens. In some cases this is provided for by leaving a space between the brick-
work of the oven and the casing, in others by having walls with loose sliding bricks
both between the walls and the casing. In all these cases the expansion sought
to be provided for is due to the summation of the expansions of all abutting
bricks in the several walls as ordinarily constructed, and which resultant is
transferred to the casing to there be met, whereas in my arrangement each brick is
free to expand harmlessly into the flues and not to add its linear expansion to that
of the others in the same course as when they abut as in ordinary wall, and so
transfer the whole expansion to the outside casing. The lateral expansion of the
bricks is harmless, and only has a tendency to turn the bricks to a greater angle
with the wall. Those forming the horizontal bond expand by pressing diagonally
the ones against which they abut; or if the walls are laid in a particular manner,
in which two horizontal bonding bricks are used, then the expansion is perfectly
free.
By so constructing the walls the expansion is provided for, as it is produced in
each separate brick, while in the old or ordinary method of constructing the walls
in which the bricks abut the resultant of all the expansions is transferred to the
outside casing which must be very heavy in order to counteract it. In addition to
providing for expansion and contraction the strength of the walls is very greatly
increased, so that they can be made much thinner without fear of buckling, and at
the same time the efficiency of the material is greatly increased owing to the fact
that the bricks composing the walls extend through the walls from flue to flue, and
are not shut off by a coating of mortar, which in practice is found to be a much
poorer conductor of heat than the fire-brick; even a thin coating like a wash
prevents to a marked degree the passage of heat. A wall constructed as described
has a greater power of conducting heat into or out of the wall than when the wall
is made of several courses of brick each parallel to the direction of the wall, for in
the case of a fourteen inch wall those bricks that are surrounded by mortar are
practically of but little if any benefit either in storing up or giving out heat. This
defect is avoided by my construction. The various valves used in the apparatus
may be of any suitable construction.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Harris Lake in the Great Seal Patent Office on the 18th April
1882.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO HOT-
BLAST APPARATUS FOR USE IN METALLURGICAL OPERATIONS." A communication
from abroad by John Coover Long, of Richmond Furnace, Pennsylvania, United
States of America, Mining Engineer and Doctor of Medicine.
This Invention relates to certain improvements in regenerative hot-blast
apparatus for heating a blast of air, gases, or vapor to be supplied to metallurgical
furnaces for intensifying the action therein.
Heretofore it has been customary to heat regenerative hot-blast apparatus by
burning therein combustible gas having a temperaturo equal to that which it has
when leaving the blast furnace or other source of supply, less that lost during its
passage to the hot-blast apparatus; this temperature in the case of the waste gases
of the blast furnace is about 300° or 400° as it leaves the furnace, less the loss in
transmission. The air used for combustion is drawn into the apparatus by means
of the draught of a very high chimney, and is used at the temperature of the
atmosphere except in one case, in which it is claimed to be heated by passing
through passages or channels in the partition walls of the apparatus.
The above-named methods are objectionable because the temperature or intensity
of the heat of the blast is limited on account of using the combustible gas at so low
a temperature, and burning it with air drawn in by a tall chimney, by which
means no intense combustion of the gas or proper distribution of the products of
combustion can be produced; further, on account of the method of heating the air
for combustion, it is evident that it can attain no very great temperature as the
passage in which it is heated cannot be made sufficiently large. The quantity of
air necessary for combustion bears quite a large ratio to the quantity of blast that
an oven can heat, and it is manifest that the surfaces of the passages do not bear
a similar ratio to the surfaces of the flues of the oven.
In
The object of the said Invention is to provide a regenerative hot-blast apparatus
by means of which a blast of air, gases, or vapors may be obtained whose tem-
perature is only limited by the resistance of the refractory material composing the
apparatus, thus greatly facilitating and economizing metallurgical operations now
employed, and rendering useful some heretofore considered impracticable ones.
most metallurgical operations it is a great intensity of heat or temperature that is
desired, for a metal may be exposed to any quantity of heat without fusing,
provided the temperature be below its fusing point, while on the contrary a short
exposure to a temperature but slightly above its melting point will fuse it, although
in the latter case it is exposed to a much smaller quantity of heat, but that of
greater intensity.
And as in the blast furnace the quantity of fuel over and above that necessary
to reduce the ore and carbonize the metal is used mainly for fusing the metal and
slag, it follows that the more intensely the blast is heated the less fuel it will be
necessary to burn in the hearth of the furnace, and as a blast can be produced by
my apparatus whose temperature is only limited by the resistance of the refractory
materials of the ovens, hence by its use a blast furnace can be worked nearer the
theoretical minimum of fuel than heretofore, and as a consequence of the decrease in
the fuel the relative necessary air supply is also reduced and the working capacity
of the furnace increased, and owing to the greater space for charges other than fuel
the cost of production is materially reduced. By using a very intensely heated

page_text: blast greater control of the furnace is obtained, and more refractory ores and flaxes
can be used, thus making valuable heretofore useless materials.
;
To this end the first part of the said Invention consists in the combination with
the peculiarly constructed ovens in which the blast of air, gases, or vapors are
heated prior to passing to the furnace of similar supplementary ovens or heaters
for heating the combustible gas which is subsequently burned in both the blast
ovens and gas heater for the purpose of intensely heating them, as is more fully
explained hereinafter; it also consists in the connections by which the gas heaters
are connected to the ovens and to each other, whereby the highly heated com-
bustible gas may be introduced into the oven or gas heater to be burned therein
it further consists in introducing into the ovens and gas heaters a forced blast of
highly heated air from the hot blast main or parts in free communication with it,
thus burning the combustible gases therein by a forced hot blast to intensify the
combustion thereof and produce an equable distribution of the hot products of
combustion and a more equal heating of the ovens and heaters, and at the same
time decreasing the amount of draught necessary to be produced by the chimney,
and it also consists in the air connections employed for this purpose, as hereinafter
set forth.
In the accompanying Drawings,
Figure 1 represents a vertical longitudinal section through the oven connection
and gas heater, showing the valves closed and the manner of forming the ovens
and gas heaters, the arrangement of the flues into a set in a decreasing series from
the combustion chambers, and the top and bottom chambers or flues and the method
of removing the dust.
Figure 2 represents a horizontal section on the line x, x, Figure 1, showing the
combustible gas connection and the cold blast and chimney connections.
Figure 3 represents a horizontal section on the line y, y, Figure 1, shewing the
hot air connections and the form of the ovens and heaters.
Figure 4 represents a transverse vertical section through the combustion chamber
of the ovens on the line y', y¹, Figure 3, shewing their construction.
Figure 5 represents a transverse vertical section through the combustion chamber
of the gas heaters on the line 3, ³, Figure 3.
Figure 6 represents a vertical section through the axis of the passage of one of
the cast iron gate or slide valves used in connection with the air and gas con-
nections shewing the method of construction.
Figure 7 represents a vertical section of the same taken at right angles to
Figure 6, and shewing the method of working and construction.
The remaining Figures will be hereinafter described.
In carrying out this part of the said Invention (reference being had to Figures 1,
2, 3, 4, 5, 6, and 7), when a continuous blast is desired at least two ovens are
employed for heating the blast supplied to the furnace. In connection with these
ovens two or more gas heaters are used and in a similar manner to the ovens as
above. In the following description two ovens for heating the blast are combined
with two gas heaters for heating the combustible gas.
The letters b, b', indicate the ovens for heating the blast, which ovens are
rectangular in form and are constructed of fire brick or other suitable refractory
materials and whose walls are supported by circular or elliptical segmental walls of
ordinary brick-work and encased in sheet iron, or the space between the oven and
the sheet iron casing may be filled with cinders, loam, broken bricks, or the like.
The said sheet iron casing is suitably strengthened at the angles to resist the strain
put upon it by the pressure of the blast and the expansion of the oven.
The roof is also covered with sheet iron put on in strips corresponding with the
width of the roofs of the flues and having upturned flange-like edges bolted
together and held down in place by girders passing over the middle of each flue
and fastened at each end to the side casing of the oven.
The interior of each oven is divided into two parts, viz., d³, the combustion
chamber, and co, the regenerator, by means of the wall 65, which extends from the

page_text: bottom to near the top, only allowing sufficient room for the horizontal flue 5.
The lowest part of the combustion chamber d³ is contracted by the walls c
Figure 4, which are run up square to the level of the perforated air cylinder o²
and blocks 82, and from thence they rapidly taper off for the purpose of producing
a more perfect combustion of the gas and for increasing the draught by means of
the diverging jets of air from the cylinders and blocks as well as evenly distributing
the flame and gaseous products of combustion to the several independent compart-
ments of the ovens, hereinafter mentioned. The upper termination of the tapering
wall is indicated by the line d³, Figure 1. The air cylinder o³ is placed in the
combustion chamber d², so that it shall be midway between the air-blocks s³ at the
angles of the side walls es in order to divide the combustible gas equally.
The said cylinder is perforated by a number of circular holes p', Figure 4, so
arranged that no two adjacent ones shall be in the same vertical plane, thus as it
were breaking joints, so that the jets of air issuing therefrom shall have different
vertical angles, the lower ones being horizontal, or nearly so, the others at
different angles, so as to equally distribute the flame throughout the chamber d².
The air blocks 82 are placed at the angles of the walls es, and are provided with
holes arranged in a similar manner to those in the cylinder o², but so that the jets
issuing from them shall not strike those from the cylinder o², but shall pass between
or interlace with them, thus having the ascending combustible gas divided by the
cylinder o³, and each current passing between two series of air jets, by the lower
of which the gas is mixed with air and then burned by the upper ones, thus having
it consumed under circumstances the most favorable for the production of a most
intense heat. The cylinder o³ and air blocks 8 communicate with the hot air
main, or parts in free communication with it, by means of the pipes p² in the
former case and the several pipes t2 in the latter case, having the regulating
valves and u³ respectively, which when once properly set always remain open
during the operation of the oven, both when it is heating the blast and when it is
burning gas. The air blocks lying on the adjacent sides of the ovens may be
connected directly by the pipe & having a valve 8 which is operated similar to
The lower part of the chamber d is provided with an opening for the hot blast
and hot gas connection m² and for the cold gas connection 2, as well as the
opening m for the removal of dust.
The upper part of the combustion chamber is provided with a series of flues e,
Figure 4, communicating with the regenerator c, and formed by the roof-
supporting partition walls l, which walls extend from the front to the back, and
from the top to the bottom of the ovens, except in the combustion chamber d², in
which they extend from the top to the oven only to the top of the sloping walls e³.
The oven is thus divided into several independent compartments, which in the
regenerator c³ are divided by the walls f³ into flues e² arranged in sets forming a
decreasing series from the combustion chamber d³, and the spaces h³, i, at the top
and, at the bottom are formed by having the walls f³ to neither reach the top
nor the bottom, except in that forming the last flue of the first set, which extends
to the top, and that forming the last Hue of the second set, which extends to the
bottom; thus, for example, having four flues in the first set, three in the second,
and two in the third set, and forming a decreasing series from the combustion
chamber or an increasing series from the cold end, and as the gaseous products of
combustion contract while cooling the surfaces over which they pass and impart
their heat as well as the capacity of the passages and absorbing materials decrease
in proportion, and conversely as the blast expands as it is heated the capacity of
the passages and heat imparting materials and the surface over which it passes
increase, thus in either case maintaining a uniform velocity and having the
absorbing and radiating surfaces and capacity of the passages or sets of flues
and the quantity of materials proportioned to the volume of the products of
combustion or blast passing through each part of the oven, and in addition thereto
the products of combustion as well as the blast are by means of the several
independent compartments formed by the walls and containing the above

page_text: described series of flues compelled to pass through the oven in independent currents,
thus obtaining a more equable heating of the oven and distribution of the blast
to be heated and consequently very greatly increasing the efficiency of the
apparatus.
The letter m indicates a small transverse channel in the inverted circular bottom
of the chamber j' extending through the oven and closed by suitable doors or
other means at the sides of the oven for the purpose of removing the dust; a similar
opening is made in the combustion chamber d
The lower parts of each last set of flues in the several independent compartments
communicate with each other, and also communicate with the chimney d' by
means of the openings in the walls, and the connections h² and pipe g³, which
is provided with the valve i, by which means communication can be cut off or
established at will. They also communicate with the cold blast supply pipe k² by
the openings t, connections h³, and cold blast pipe k having a valve 2, by which
communication can be established or cut off at will. The ovens or combustion
chambers d² communicate with the hot gas supply main e¹ by means of the pipes m³
provided with valves n' for the purpose of receiving hot gas for combustion, and
with the hot blast main by means of the pipes m³ and the vertical pipes u¹
provided with the valve c² and branch 62 for the purpose of carrying the hot blast
from the oven to the hot blast main l.
All of the pipes or connections and mains are lined with fire brick, with the
exception of the cold blast supply pipe.
The gas heaters are constructed similarly to the ovens internally, but may be
made smaller by decreasing the number of compartments or the number of flues,
or both.
In the Drawings they are shewn as made smaller by decreasing the number of
flues. The combustion chambers may be constructed like those of the ovens, or
they may be made with either the air cylinders or air blocks alone. In any case
their connection to the hot air main for receiving hot air for combustion is made
by the pipes 1 having valves t¹, or the pipe n¹ having a valve o', by which commu-
nication can be established or cut off at will. The letter e¹ indicates the hot gas
main, into which the gas heaters deliver the gas which they have heated through
the hot gas connection pipe g', provided with the valve h, by which communi-
cation can be established or cut off. The gas heaters also communicate with the
main e¹ by means of the pipes f, f', having the valves h¹, by which the ovens can
be supplied with hot gas for combustion when they are being beated. The hot
gas for combustion may be supplied directly from one heater to the other by means
of the pipe, having a regulating valve k' extending from the combustion chamber
of one gas heater to that of the other. The valve in this case after being
properly set always remains open. The combustion chambers 66 are also connected
with the supply main t by means of pipes v' having valves a. The gas heaters
are connected with the chimney d¹ by means of the connections p, valves r, the
horizontal pipes w, having valves a³, and connecting with a vertical pipe 65 and
horizontal pipe c¹ to the chimney.
They are also connected with the cold gas supply main t for the purpose of
receiving the gas to be heated by means of the pipe s, valve r, and connection p.
Figures 6 and 7 are sectional views of a cast iron slide valve used in connection
with my apparatus. The valve a' is a wedge-shaped gate or slide having a
rectangular head and stem e*. The valve a' and head and stem are formed with a
pipe, which after descending to the bottom of the valve is bent so as to be as near
the surface of the valve as possible, and at the same time to be constantly ascending
toward the stem, up which it goes, and is connected to water and waste pipes. It
is also provided with a rack and counterbalance pulley, and is operated by means
of a single pulley. The valve chest is formed in two parts, both made of cast iron
and cooled by water passing through continuous wrought iron pipes. The lower
part is made wedge-shaped to correspond with the shape of the valve, and is pro-
vided with a seat formed in one piece, and having lugs or projections for fastening

page_text: it to the casing; this seat is planed out on the face sides to fit accurately and air-
tight the planed faces of the valve. It is cooled by two sets of pipes, one for
each face of the seat, which pipes pass directly in and across the opposite side,
then down to near the bottom, then up and around the seat of the valve, and
then up the side of the inlet, and across and out at the opposite side into the waste
pipe.
The upper part is made somewhat smaller than the lower part, to which it
is bolted so as to fit the square head of the valve, so that the instant the valve is
moved upward it leaves its sloping seat and is supported by its head moving
against the sides of the upper part, thus very much decreasing the wear on the
valve surfaces. The valve is cooled by a spiral pipe attached to proper waste and
water pipes. The stuffing box is made in the ordinary manner.
In practice at least two gas heaters are used in combination with at least two
ovens for heating the blast, but in cases where the apparatus is used for heating
anything but air it will be necessary to use a set of two supplementary ovens to
beat the air for combustion, and having an additional hot air main and connections
if it is desired to have hot air for burning the combustible gas. When heating a
blast of air, and heating both the ovens and heaters by burning hot gas with hot
air, the operation is as follows, all the valves being closed-In the oven b' I open
the cold blast valve ³, by which cold air is admitted and passes through the
compartments and series of flues to the combustion chamber; then I open the hot
blast valve c, allowing the air to pass into the hot blast main l, and thence to the
blast furnace. Then in the gas heater a¹ I open the cold gas valve r and the hot
gas connection valve h¹, by which means gas is admitted and passes through the
separate compartiments and flues, and into the hot gas main e¹. Then in the oven b
I open the chimney valve and the hot gas supply valve n² to admit gas into the
combustion chamber and open the valve in the pipe p², and the valves u³ in the
pipes t, to supply air for burning the gas, which is then ignited. The regulating
valves and u² when properly set always remain open.
Then in the gas
heater a I open the chimney valve a³, and the valves t' in the pipes r¹ to supply
air for combustion. I then open the hot gas supply valve h' to admit combustible
gas from the main e¹ and ignite it, or the gas can be supplied directly from one
beater to the other by means of the pipe by opening the regulating valve k',
which when properly set remains open. The products of combustion pass through
the compartments and flues to the chimney d¹ by pipes w, b, and c'.
After a longer or shorter interval, that is, when both the oven 6 and gas heater a
have become heated to a sufficient degree, the ovens and heaters are reversed at
the same time, or the ovens at one time and the heaters at another, as desired.
Supposing that the reversal is to take place at the same time I proceed as follows:-
In the oven I close the hot gas valve n' and the smoke or chimney valve and
open the cold blast valve and the hot air or blast valve c, by which means hot
air passes into the main . Then in the oven b¹ I close the hot blast valve c² and
the cold blast valve 12, and open the chimney valve and the hot gas valve n³,
and the regulating valves u² and 2 on the pipes t2 and p², which when properly
set always remain open, both when the oven is heating blast or being heated by
burning gaa. Then in the gas heater a I close the air supply valves t¹ and the hot
gas supply valve h¹ if combustible gas is admitted that way; then I close the
chimney valve a³ and open the cold gas supply valve rand the gas connection
valve h, thus introducing hot gas into the hot gas main e¹.
Then in the gas heater a¹ I close the cold gas supply valve r and open the
chimney valve a³ and close the hot gas connection valve h and open the hot gas
supply valve h¹, if gas for burning is supplied in that way, and then open the air
supply valve o¹.
In the subsequent reversals I proceed in the same way, and the length of the
intervals between the said reversals after the apparatus is in full operation depends
on the time it takes for the ovens and gas heaters to become sufficiently heated
and that required for them to part with their effective heat.
It also depends upon the temperature of blast desired. Before the first reversal

page_text: the oven b and the heater a were heated by means of cold gas burned with cold
air; but after the first reversal, the gas passing through the gas heater a and the
air passing through the oven b are both heated several hundred degrees, hence the
gas heater a¹ and oven 6¹ are being heated by burning hot gas with hot air, thus
acquiring in an equal interval a temperature several hundred degrees hotter than
the oven 6 and the gas heater a did by burning cold gas with cold air. Now after
a second reversal the gas heater a' and oven 6' supply air and gas several hundred
degrees hotter than the heater a and oven b did, and consequently the heater a and
oven b in an equal interval, by the combustion of this more highly heated gas
with the more highly heated air, become several hundred degrees hotter yet, and
after reversal furnish still hotter air and gas, and so one after each reversal hotter
gas is burned with hotter air, thus developing a temperature of blast which is only
limited by the resistance of the refractory materials composing the apparatus.
By properly proportioning the quantity of blast to be heated to the size of the
ovens and heaters, and the quantity of gas to be heated and regulating the intervals
between reversals, any temperature of blast can be maintained, provided it be not
beyond the resistance of the material, or the temperature may be varied by the
operator as demanded by the exigencies of the metallurgical operations.
The gas heaters are also arranged so that they can be supplied with cold gas for
combustion from the main t by means of the branches or pipes v¹ having the
valves x¹. In this case the valve k¹ on the connecting pipe is closed; and the
method of operating is the same as when the gas for consumption was obtained
from the hot gas main e¹ by means of the valve k¹, excepting that the valve x* is
used in place of the valve k'. If it is desired a mixture of hot and cold gas can be
used by having the valve k¹ partially opened.
The ovens are also so arranged that they can burn cold gas in connection with
hot air. The cold gas is supplied from the cold gas main t by the branches 2
provided with valves w³, and in the reversals these valves w³ are substituted for
the hot gas valves n², but otherwise it is the same, they can also be worked with
a mixture of hot and cold gas, and in this case it is necessary to use both of the
valves w³ and n³ to admit the gas.
When using cold gas the gas heating part of the apparatus may be dispensed
with or held in reserve in case an intensely hot blast is desired, as when the blast
furnace is working cold and badly.
Another form of my improved regenerative hot blast apparatus is shewn in
Figures 8 to 25 of the accompanying Drawings, in which
Figure 8 is a horizontal section through the perforated air cylinders and blocks
on the line z, z, Figure 12.
Figure 9 is a horizontal section through the gas and air connections on the
line y³, y, Figure 12.
Figure 10 is a horizontal section through the air cylinders and blocks on the
line 2¹, ¹, Figure 13, shewing a modification of the dividing pipe, distributing main
connections, and combustion chamber.
Figure 11 is a horizontal section on the line y', y', Figure 13.
Figure 12 is a vertical longitudinal section on the line a³, ³, Figures 8 and 9,
shewing the hot and cold gas, hot and cold air, and chimney connections.
Figure 13 is a longitudinal vertical section on the line a¹, x', Figures 10 and 11
shewing the hot and cold gas, hot and cold air, and chimney connections, the
same being a modification of the parts shown in Figure 12.
Figure 14 is a vertical section through the combustion chamber on the line u, u,
Figures 8 and 9.
Figure 15 is a vertical section through the combustion chamber on the line u¹, u¹,
Figures 10 and 11 showing a modification of the dividing pipes, connections, mains,
and combustion chamber in Figure 14.
Figure 16 is a vertical transverse section of the oven on the line v, v,
Figures 8 and 9, and Figures 10 and 11.
Figures 17, 18, and 19 are perspective views of portions of the walls shewing

page_text: their construction so as to provide against the effects of expansion and
contraction.
Figure 20 is a longitudinal vertical section on the line y³, y, Figure 21, of an
oven whose regenerator flues are arranged in groups or sets, shewing the modified
method of forming the horizontal distributing flues.
Figure 21 is a horizontal section of the same on the line x, x², Figure 20.
Figure 22 is a plan or top view of four combined ovens and gas heaters arranged
in couples directly connected, having two gas supply mains at their hot or
combustion-chamber sides.
Figure 23 is a plan or top view of four combined ovens and gas heaters arranged
in couples and having a continuous gas supply main connected to their several
combustion chambers.
Figure 24 is a plan or top view of three combined ovens and gas heaters arranged
above a common gas supply main.
Figure 25 is a plan or top view of three ordinary regenerative hot blast ovens
altered in accordance with the said Invention without adding a fourth ordinary
oven, or a combined oven and gas heater.
The object of this part of the said Invention is to provide a regenerative hot-
blast oven which can be used either for heating the blast or for heating the
combustible gas burned in the apparatus, so that it may be substituted for either
a special blast oven or a special gas heater, or both, in order to heat the combustible
gas prior to its being burned in the apparatus, whereby a more intense heat may
be developed therein; then when the apparatus is heated by the combustion of gas
which has not been heated after leaving its source, and which oven is so arranged
with suitable connections that it can be used either for heating the blast or for
heating the combustible gas by being heated for each object specially, or it can be
used as a gas heater without being specially heated therefor by making available
the large quantity of heat yet in the oven when used to heat the blast after it has
lost that portion of its heat which is effective in heating the blast to the required
temperature, and which combined blast oven and gas heater may be substituted
for either the special gas heaters or blast ovens, or for both as aforesaid, so that
when used as a gas heater it can in case of failure or repair of the blast ovens be
used for heating the blast, thus furnishing a duplicate set of blast ovens without
increasing the cost of the plant, and at the same time avoiding the danger incident
to a failure of the hot blast by the giving out of the special blast ovens.
And in
addition thereto the object is to furnish means for altering the regenerative hot
blast apparatus now in use to my improved system, either by adding thereto one
or more combined blast ovens and gas heaters directly connected thereto, so as to
form couples consisting of an oven used as a gas heater and an oven used as a
blast oven, as hereinafter described, or by connecting all to a common hot gas main,
and in both cases adding to the other ovens the necessary hot and cold gas and air
connections, so that any or all may be used as blast ovens or gas heaters as desired.
Or a plant consisting of four blast ovens may be altered to my system when the ovens
are arranged along a common cold gas supply main having no other branches by
putting in the main a valve between the ovens and blast furnace or other source
of gas supply, and then using the portion thus cut off as a hot gas main, or in case
each pair of valves has a common gas supply main without other branches, then by
cutting it off as above described a hot gas main is formed leading from one oven
to the other and the pair is worked as a couple; in both cases the necessary
additional hot and cold gas and air connections are made so that any oven may be
used as a gas heater or blast oven as desired.
In the case of a plant consisting of three ovens it may (owing to the fact that
the combustible gas necessary to heat the apparatus has a much smaller volume
and less velocity and greater heat absorbing power than the blast, while the
specific heat is about the same in both cases) be altered to my improved system
without increasing the number of ovens by altering them into combined blast
ovens and gas heaters by adding to the ovens the necessary cold gas main and

page_text: connections at the cool end in order to supply the gas to be heated, and at the hot
end a hot gas main connecting all of the ovens, or in case the ovens have a common
gas supply main, then by cutting it off by a valve between the ovens and blast
furnace or other source of gas supply. A hot gas main is formed, and using the
ordinary gas connections with the ovens for the passage of the heated gas. If it is
⚫ desired to burn the heated gas with hot air, then the necessary connection must be
made as hereinafter described; but if cold air is used for combustion, then the
ordinary air connections can be used.
A plant of three blast ovens may also be altered by adding one of the combined
ovens and gas heaters, and the necessary blast, and gas, and air connections to the
other ovens, and cutting off the gas supply main as above described.
The object is also to provide means for heating a mixed blast of air and vapor,
and at the same time furnish pure highly heated atmospheric air for combustion in
the ovens and gas heaters; also to provide for expansion and contraction, and for
the equal heating of the oven and equal distribution of the gas or blast to be
beated.
In this Specification, when speaking of cold and cool gas, I mean gas at the
temperature it has after leaving the blast furnace or other source of supply, less the
temperature lost in transmission to the apparatus in which it is burned, that is,.
combustible gas which has not been heated after leaving the apparatus in which it
was produced, and prior to its introduction into the apparatus in which it is burned.
The tendency of modern blast furnace engineering is to reduce the temperature
of the waste gases from the blast furnace as low as possible, and is a result of the
widening of the blast furnace throat, as now done in the more modern blast furnaces,
in order to save fuel and improve the working of the furnace; in fact, one very
high authority says that the temperature of the waste gases of a blast furnace
should not exceed 212° Fahrenheit, hence the necessity of having means for heating
the gas so as to be able to command an intensely heated blast.
This part of the said Invention consists in the regeneration hot-blast oven
having cold blast or air, and cold gas and chimney connections at the cool or
chimney end, and having at the hot or combustion-chamber end hot blast and hot
gas delivery connections, as well as the hot and cold gas, and hot and cold air
connections for supplying the necessary hot or cold gas to heat the oven, by being
burned therein with hot or cold air, or with a mixture of hot and cold air, the
walls of the said oven being so constructed as to provide for expansion and con-
traction of the several walls and the roof, being constructed as shewn.
It also consists in the horizontal flues and the several connecting pipes and flues
or distributing mains at the cool end, whereby the gas or blast to be heated is
equally distributed, and in the flues, pipes, mains, and valves at the hot end,
whereby the combustible gas to be burned therein is equally distributed. It also
consists in the combustion chamber divided into single or double compartments by
longitudinal walls extending from the roof, and to or near the bottom, and having
the a'r blocks or cylinders extending through the casing, and into the wall
separating the combustion chamber and the regenerator.
It also consists in the combination of the pipes and valves by which hot air is
supplied for combustion in the ovens or gas heaters, independent of the hot-blast
main.
It further consists in the combination of one or more of the above described
ovens or gas heaters, with one or more ordinary regenerative or above described
ovens used as blast ovens.
It further consists in the combination of two or more combined ovens and gas
heaters which are used successively for heating the combustible gas.
It further consists in the combination with two or more ordinary regenerative
hot blast ovens of the necessary hot and cold gas mains and connections by which
they may be used as blast ovens and gas heater, either successively or in couples,
all essentially as hereinafter more particularly described.
The combined oven and gas heater is constructed of ordinary fire bricks, or of

page_text: similarly shaped blocks of fire-brick or other refractory materials, whose dimensions
vary with the temperature of the blast desired, so that all of the material in the
bricks or blocks may be useful in storing up and giving out heat, for with different
temperatures the depth to which the effective heat penetrates, and the extent to
which it is given off vary. The combined oven and gas heater is rectangular in
form, and is supported by curved segmental walls A of common or red brick, sand,
slag, or the like, and encased in sheet iron; or it may be made without the sup-
porting walls A with a rectangular casing of sheet iron properly supported by
outside girders or bracing; or the sheet iron may be put on horizontally in strips,
whose length is equal to the width of the several sides of the oven, and with the
edges of the strips upturned flange like and fastened, thus providing for lateral
pressure. The said oven or gas heater is divided into two parts; B, the regenerator,
and C the combustion chamber by the wall D which extends from the bottom to
near the top, but allowing space for the horizontal flues S¹, and from side to side.
It is also divided into several independent compartments, either double or single,
by means of the roof supporting walls E which extend from front to rear, and from
the roof to the bottom, except the regenerator part of those in the middle of the
double compartments which rest upon arches forming the horizontal flues G, and in
the combustion chamber in which those forming the double compartments extend,
either as in Figure 14, to below the connections I, or as in Figure 15, to the top of
the horizontal flue O. They may if desired extend to the bottom, in which case
each compartment would have a passage as at I, Figure 14, for removing the dust.
The walls E in the middle of the double compartments may extend to between the
air blocks or cylinders H and the connection I, for the passage of the blast and gas,
as in Figure 14, or they may be cut off above the air cylinders or blocks, as also
shewn in Figure 14, but in this case the air cylinders or blocks are supported by
the walls J, to prevent sagging from the effects of heat.
The combustion chamber may be constructed as in Figure 15, in which the walls E
in the middle of the compartments may be made single by extending all of the
walls E to the top of the flue O, and each compartment is provided with a con-
nection I. In order that there may be more certainty of an equal distribution of
the combustible gas and the heated products of combustion, the mouths of the
connections I are placed in the middle of each of the compartments either double
or single. The air for combustion is introduced through the perforated blocks or
cylinders H, placed either in the middle walls E of the compartments, as in
Figure 14, or in the walls which form the sides of the single or double compartments,
as in Figure 15.
The air cylinders or blocks H extend through and even with the casing and into
the wall D, so that in case of repair they may readily be replaced from the outside
of the oven by removing the connecting pipes J and connections K¹. The air
blocks or cylinders may be made of fire clay or brick, metal, or other refractory
material, and, if necessary, may be cooled by causing a current of air or water to
flow through a pipe K¹, which may be embedded therein. The air cylinders or
blocks H are connected by pipes J', having regulating valves M, to the pipe K
having a valve L. This pipe K connects with the pipe N communicating with the
combustion chamber C, and having a valve O¹, Figures 8 and 10, which may be
made in the form of a check valve by having a suitably sized seat valve so balanced
as to be automatic, so as to prevent any back flow of air when the oven is being
heated or is heating gas, but when the oven is heating the blast to open automatically
and allow the air necessary for combustion in the other ovens to flow into the
pipe N, and thence by the pipe A¹ which connects it to the similar pipes N of the
other ovens. When the ovens are in the same line, as in Figure 24, the pipe N
extends only beyond the pipe K to meet the pipe A¹, which joins all the pipes N;
but when the ovens are opposite each other, as in Figures 22 and 23, then the
extension of the pipes N, after connecting by the pipes A¹, to meet the corresponding
pipes N of the opposite ovens is necessary to complete the circuit of the passages
for the air for combustion independent of the hot blast main.

page_text: If in all of the compartments, except that next the cold blast entrance, a blast
of steam or vapour be introduced in the connections F', together with the cold air
introduced by the cold blast connections and valve H', then in all of the compart-
ments there will be a mixed blast, excepting in the first, in which it will be of pure
atinospheric air, and this will by the connection N be furnished for combustion,
while a mixed hot blast will be supplied to the furnace.
The pipe N is also connected to the cold air main O' by the pipe Q2 having a
valve P, by which means cold air may be supplied for combustion.
The dust may be removed from the combustion chamber through the openings I',
which may also be used when igniting the gas. The dust in the regenerator is
removed through the openings A₁. The several compartments of the combustion
chamber are also provided with the connections to the distributing main O
connected to the dividing pipes P, which enter the main O midway between the
connections I, so as to equally distribute the combustible gas burned in the oven.
The main O may be formed like the main G¹ outside of the oven, as in Figures 9
and 12, when the connections I will be horizontal; or the main O may be formed
in the bottom of the combustion chamber by arching it over, as in Figures 10, 11,
15, and 21, and making the vertical connections I to the several compartments;
the outside connections will be, by the dividing pipes P entering the oven and
main O, thus formed midway between the connections I. The pipes P are connected
to the opposite oven by the pipe Q, having a valve C¹, either directly or by means
of similar dividing pipes and distributing main, as illustrated in Figures 22 and 23.
The pipe Q is connected to the hot blast main B¹, Figures 12 and 13, by means of
the vertical pipe R, valve S, and branches T. The opposite oven is connected
similarly to the hot blast main B' by th connection F.
In the case of a plant of four ovens connected directly with opposite ones, thus
forming two couples, as in Figures 22 and 23, in each of which one oven is used as
a gas heater, while the other is used as a blast oven, the pipe Q connecting each
couple is connected with the corresponding pipe Q of the other couple by the pipe Pl
in free communication there with, and having valves Q', by means of which hot gas
may be supplied from one oven used as a gas heater by opening the valves Q₁ to
pass the proper quantity of gas and then leaving them open.
The pipe Q is also connected to the source of cold gas supply by the valve W¹
and main W, by means of which cold gas may be supplied to the ovens or gas
heaters for combustion. The main W may be used as a hot gas main by placing a
valve W in it between the ovens and source of cold gas supply, and may be common
to the opposite ovens or gas heaters, as in Figure 23, and connected to each by
connections having valves W'. This construction will admit of three ovens in a
plant of four ovens being used, or will give the advantages of having gas heaters in
a plant of three combined ovens and gas heaters. In case of the three regenerative
hot-blast ovens in the apparatus now generally used, they may be altered to my
improved system, as in Figure 24, by adding the necessary hot air connections for
supplying the air necessary for combustion, if it is desired to burn the gas by means
of a blast of hot air; or the ordinary air connections may be used, as in Figure 25,
by placing a valve W' in the cold gas supply main W, thus cutting off communi-
cation with the furnace or other source of cold gas supply, and forming a hot gas
main of the portion thus cut off. The present gas supply connection thus serves
a cold
for the passage of the heated gas into and out of the oven, and I then add
gas main Ws and connections L' and R' at the cool ends in order to supply the
gas to be heated in the apparatus, as in Figure 25. The above construction of
the main W will allow of the apparatus being extended as in the case of four ovens
and gas heaters, with a minimum cost, by additional ovens to the common main.
The regenerator B is composed of the walls E and D¹ forming the vertical
flues T. The walls D' extend from the horizontal flues G as high as the wall D
so as to allow sufficient space for the horizontal flue S'. The flues T¹ are arranged
in one set, as in Figures 12 and 13, so that the products of combustion and gas or
blast to be heated pass through the regenerator in but one direction, that is, the

page_text: former passing down while the latter pass up, thus decreasing the friction. The
roof-supporting walls E extend from the bottom to the roof except in the double
compartments, in which they commence at the top of the arches supporting them.
The flues G are either single or double; in the latter case they are formed by the
arches carrying the walls D₁ and middle walls E of the double compartments.
In either case they have the connections F1 placed in the middle of the compart-
ments for the passage of the blast or gas to be heated as well as the products of
combustion. The connections F¹ connect with the distributing main G' having
cold blast connection and valve H' and chimney connection M¹, and communicating
with the cold gas supply main W3 by the dividing pipes L' having the valve R'.
The pipes L' are so placed as to be midway between the connections F¹ which
open into the middle of the compartments so as to equally distribute the gas to be
heated. The distributing main G¹ and connections F¹ also serve to equally dis-
tribute the blast to be heated. If the flues are arranged as in Figure 20, then the
distributing main G' may be formed in the lower part of the last set of flues by
arching it over and making the main G₁ thus formed continuous by removing
parts of the walls E and making vertical openings corresponding to the con-
nection F and opening into the middle of the compartments. The connection of
the cold gas main W³ will then be by the dividing pipes L' having the valve R¹,
and entering the oven and main G' thus formed midway between the openings F¹
which may be made into each compartment separately, or may open into two
jointly; the chimney and cold blast communications may then be made directly to
the oven and opening into the main G¹ thus formed, as shewn in Figure 21. The
vapour pipe J having a valve K³ has branches L³ excepting at the point next the
cold blast connection (Figures 8, 9, and 12), into which they discharge the steam
or vapour. In case of forming the main G¹ in the oven, as in Figures 20 and 21,
then the branches L2 open into the compartments above the flue G¹ if it is desired
to heat a mixed blast.
The roof is formed of a number of rectangular blocks N" and wedge shaped
blocks R of fire brick or other refractory material, whose length equals the
distance between the centres of the roof supporting walls E upon which they rest.
The wedge-shaped blocks are placed in those parts which are moved when access is
desired, as shewn in Figures 12 and 13.
The roof blocks are covered with strips of sheet iron E¹ whose width equals the
length of the blocks, and having upturned flange-like edges C* which are bolted
together and held in place by the guides H* placed transversely upon the flanges
and fastened to the outside casing, as shown in Figures 14, 15, and 16. The
strips El extend only over each portion, either that over the wedge-shaped blocks,
and which is removed when access is desired as in cleaning, or over that formed
by the rectangular blocks. The strips E' covering the wedge-shaped blocks may
slightly overlap the strips E' covering the rectangular blocks to which they are
bolted, and may if necessary be held down by girders; or the strips E' covering
the wedge-shaped blocks may meet the strips El over the rectangular blocks with
upturned flanged edges C, as in Figures 12 and 13, and be bolted together. In
case access is desired for cleaning the girders (if used), the sheet iron strips E¹ and
the wedge-shaped blocks under them may be removed.
The several walls of the oven and gas heater are constructed of ordinary fire-
bricks or similar rectangular blocks of fire brick or other refractory materials,
whose dimensions vary with the temperature of the blast desired and the tempe-
rature to which they are exposed, so that in case of the hotter blast they may be
made larger as the depth to which the effective heat is absorbed and the extent to
which it is subsequently given out increase with the temperature.
The bricks or
blocks are laid diagonally in reverse directions in the adjacent walls or courses in
the same horizontal planes, and in the adjacent courses in the same vertical planes
as shown in Figures 17, 18, and 19, and they are laid on edge or flat, as above
described. The walls may also be made by having the bricks or blocks placed on
end and overlapping diagonally to different. distances. The bond is formed by

page_text: having a horizontal bonding brick B' extending from one wall to the other, and
which is itself held in place and bonded by the vertical bonding bricks D³ placed
at each side and alternate ends of the horizontal bonding bricks B. The bonding
bricks D extend from the middle of one horizontal bonding brick B3 across the
next and to the middle of the third, and in addition the bonding bricks D2 break
joints, as in Figure 17. The bonding bricks D may also be placed horizontally,
as shown in Figure 18. The walls may also be bonded horizontally by a bond
brick E' extending from the middle of one wall to the middle of the bond brick B³,
as in Figure 17.
The walls may be made by laying the bricks flat and diagonally, and in reverse
directions, as shown in Figure 19, and bonded by a single bond brick F2, and by
a part of a brick 12 and a whole brick G extending into the side wall, as shewn.
The next bond formed in this manner by a whole brick G2 and part I is so arranged
that the whole brick G' shall extend into the other wall; this construction of the
walls E and D' is continued until they reach the top of the flues T¹, when the
walls are constructed by laying the bricks diagonally and in reverse courses as the
walls D¹ were constructed, as shown in Figure 18, until they reach their proper
height. By having the bricks laid diagonally and in reverse courses, and bonded
in the manner shown, the effects of expansion and contraction are effectually
provided against, which is a matter of the greatest importance in regenerative hot
blast ovens.
In some cases this is provided for by leaving a space between the
brick-work of the oven and the casing, in others by having walls with loose sliding
bricks both between the walls and the casing. In all these cases the expansion
sought to be provided for is due to the summation of the expansions of all the
abutting bricks in the several walls as ordinarily constructed, and which resultant
is transferred to the casing to be there met, whereas in my arrangement each brick
is free to expand harmlessly into the flues and not to add its linear expansion to
that of the others in the same course as when they abut as in the ordinary wall,
and so transfer the whole expansion to the outside casing. The lateral expansion
of the bricks is harmless, and only has a tendency to turn the bricks to a greater
angle with the wall; those forming the bond as B2 expand by pressing diagonally
the ones against which they abut, or if the walls are laid, as shown in the lower
part of Figure 18, in which two bonding bricks B are used, then the expansion is
perfectly free.
By so constructing the walls the expansion is provided for as it is produced in
each separate brick, while in the old or ordinary method of constructing the walls
in which the bricks abut the resultant of all the expansions is transferred to the
outside casing, which must be very heavy in order to counteract it. In addition
to providing for expansion and contraction the strength of the walls is very
greatly increased, so that they can be made much thinner without fear of
buckling, and at the same time the efficiency of the material is greatly increased
owing to the fact that the bricks composing the walls extend through the walls
from flue to flue and are not shut off by a coating of mortar, which in practice is
found to be a much poorer conductor of heat than the fire brick; even a thin
coating like a wash prevents to a marked degree the passage of heat. A wall,
constructed as shown, has a greater power of conducting heat into or out of the
wall than when the wall is made of several courses of brick, each parallel to the
direction of the wall, for in the case of a fourteen inch wall those bricks that are
surrounded by mortar are practically of but little if any benefit either in storing
up or giving out heat. This defect is avoided by the construction shown in
Figures 17, 18, and 19. The various valves used in the apparatus may be of any
suitable construction.
Methods of working.
When using the combined blast oven and gas heater as a gas heater supposing all
valves closed, I proceed as follows in order to heat it, that is to say :-I open the
chimney valve M' and then admit air for combustion by opening the valve L and the
regulating valves M, which remain open after having been properly set. I then

page_text: open the valve W' to admit cold gas when the main W is used as a cold gas main,
or hot gas when the main W is used as a hot gas main, by closing the valve W*
when the apparatus is arranged in couples, as before described, then the hot
combustible gas may be admitted to one gas heater from the other through the
pipe P¹ by opening the valves Q1 to the proper extent and leaving them open.
After the apparatus has become sufficiently heated, in order to heat the combustible
gas I proceed as follows, that is to say:-I close the air supply valve L, then close
the gas supply valve W₁ if cold combustible gas is admitted, but if the main W is
used as a hot gas main then the valve W' remains open or is opened more fully to
allow the heated gas to pass into the main W used as a hot gas main. I then
close the chimney valve M and open the cold gas supply valve R¹ to admit cold
gas from the main W³. Then if the hot gas passes directly to the opposite blast
oven I open the hot gas valve C¹. The valves Q' remain open so as to pass the
hot gas from one oven used as a gas heater to the other, thus furnishing a supply
of highly heated combustible gas. Then after the gas heater has parted with its
effective heat it is reversed and again heated when used in couples as follows, that
is to say: I close the hot gas valve C' and the cold gas valve R¹ and open the
chimney valve M¹ and air supply valve L. The hot gas to be burned is admitted
through the valves Q which remain open; if cold gas is burned, then it is admitted
from the main W by the valve W¹. In case the main W is used as a hot gas main,
then the valve W₁ remains open or is only partially closed.
When the combined oven and gas heater is used as a blast oven in order to heat
the oven, all the valves being closed, I proceed as follows, that is to say :-I open
the chimney valve M', then open the hot gas valve C¹ if the gas is supplied that
way, or if the gas is supplied by the main W used either as a hot or cold gas main,
I then open the valve Winstead of C¹. I then open the air valve Land the regulating
valves M, which when properly set remain open, by which means the oven becomes
highly heated by burning therein a highly heated gas with a blast of highly heated
air. After the apparatus has become sufficiently heated it is reversed and a highly
heated blast produced as follows:-I close the gas supply valve C or W', as the
case may be, then close the chimney valve M¹ and open the cold air blast valve H',
and the steam or vapour valve K* if a mixed blast is to be heated. I then open the
hot blast valve S, by which means a blast of highly heated air or a mixed blast of
air and vapour is supplied. The valve L always remains open when the apparatus
is used as a blast oven. After the apparatus has parted with its effective heat it is
reversed and again heated by closing the hot blast valve S, then closing the cold air
valve H and the valve K' (if used) and opening the chimney valve M². (It may
be necessary owing to the pressure on the valve M¹ to open a supplementary valve
or a dust door opening outwardly to relieve the pressure by allowing the air to
escape, or a slide valve may be substituted for the seat valve). I then open the
gas supply valve C₁ or W¹, as the case may be.
When one or more of the above described combined ovens and gas heaters are
used in combination, they are directly connected with one or more blast ovens,
thus forming couples, each consisting of a gas heater and blast oven.
In the reversal of the couples the blast ovens must be reversed first in the following
manner:- - Supposing that in one couple A and B, Figures 22 and 23, the gas
heater As is, as above described, heating the combustible gas which is burned in its
blast oven B, as above described, and that in the other couple C and D, Figures 22
and 23, the gas heater C³ is heated while its blast oven D³ is heating the blast, as
above described. Then after the blast oven D and gas heater A, or either of them,
has parted with its effective heat, or the other oven B³ and gas heater C, or either of
them, has become sufficiently heated, the reversal is as follows:-Always commencing
with the blast oven B³ which is being heated, in which I close the hot gas valve C'
and the chimney valve M', and open the cold blast valve H¹ and the hot blast
valve S, so that there may also be a hot blast, giving to the furnace a pressure
maintained in the pipes N, pipes A¹, and pipes K, and their connections. I then
reverse the gas heater C³ in the other couple, which has been heated by closing the

page_text: air valve and the chimney valve M², and opening the cold gas valve R¹, so that
there may always be a sufficient supply of heated gas. I then reverse the other
blast oven Do, which has been heating the blast by closing the hot blast valve S,
and the cold blast valve H', and opening the chimney valve M¹ and the gas supply
valve C, and the air supply valve L, which then remains open while the oven is
used as a blast oven. I then reverse the other gas heater A³ by closing the cold
gas valve R¹, and opening the chimney valve M¹ and the air valve L, gas for
combustion being admitted by valve W' or Q', as the case may be, as above described.
Then after a suitable interval the apparatus is again reversed in the same manner.
In the case of altering (as in Figure 25) a plant of three ordinary regenerative
hot-blast ovens to my improved system without adding a fourth oven or gas heater,
and working them or three of the above described combined blast ovens and gas
heaters, as in Figure 24, or three combined ovens and gas heaters in a plant of four
arranged along a common hot gas main, as in Figure 23, in each case working
them as blast ovens and gas heaters successively, and in each of which cases the
heated gas is conveyed from the oven in which it is heated to the oven in which it
is burned by means of a common hot gas main, or a portion of the usual cold gas
main W cut off for the purpose of being used as a hot gas main by means of the
valve W³, as before described, so that at any time cold gas may be used in the
usual manner. The heated gas is burned by a blast of heated air, as in Figure 24,
or by ordinary methods in other ovens, as in Figure 25.
This method of working with three ovens is somewhat different from the above
described methods, and is based on the fact that the oven which has heated the
blast still contains a large amount of heat, which is not of a sufficiently high
temperature or intensity to heat the blast to the desired degree, but which can
heat the combustible gas sufficiently high, owing to the gas having a much less
volume and velocity, and greater heat absorbing power than the blast; the method
is as follows-Supposing all the valves closed, then in the first oven H³, I open the
cold blast valve H₁, then the hot blast valve S; then in the second oven 15 I open
the cold gas supply valve R¹ at the chimney side of the oven, and then open the
gas valve W' at the combustion-chamber side of the said oven; then in the third
oven K' I open the chimney valve M¹ and the gas valve W₁ at the combustion
chamber side to admit the gas to be burned, and then open the air valve L,
Figure 24, or the ordinary air valve L, Figure 25, to supply air for combustion, by
which means this oven K³ becomes heated; then after a suitable interval the
apparatus is reversed as follows:-Always commencing with the oven K³ which is
being heated, in which case I close the gas supply valve W¹ at the combustion
chamber side, and the air valve L supplying air for combustion; I then close the
chimney valve M' and open the cold air blast valve H¹, and then the hot blast
valve S; then in the other oven H³ through which the blast is passing, I close the
bot blast valve S and the cold blast valve H', and open the chimney valve M¹ to
allow the air in the oven H to pass out through the chimney; I then open the gas
valve W' at the combustion chamber, and after a suitable interval so as to allow
the air in the oven to be drawn into the chimney and the oven to be filled with
gas, in order to avoid the danger of an explosion from a mixture of air and gas in
the oven and hot gas main, I close the chimney valve M³ and open the cold gas
valve R' at the chimney side of the oven, thus having gas pass through the oven
and into the hot gas main; then in the other oven I³ through which gas is
passing I close the cold gas valve R' at the chimney side of the oven, and open the
chimney valve M¹ and the valve L to supply the air necessary for combustion, by
which means the oven 15 becomes heated; then after the oven K³ which is
heating the blast has parted with its effective heat, or the one I³ which is being
heated has become sufficiently heated, the apparatus is reversed in the same
manner, always commencing with the oven I which is being heated, and then the
oven K³ which is heating the blast, and lastly, reversing the oven H³ which is
heating the gas.
After the first reversal the apparatus is heated with cold gas burned with hot or

page_text: cold air depending on the system used, while a heated blast is being furnished;
after the second reversal the apparatus is heated by the hot gas burned with the
hot or cold air depending on the system used, in addition to furnishing a highly
heated blast to the furnace, and so on; after each reversal hotter gas is used with
hotter air, and thus after each reversal a hotter temperature is developed. In
changing the oven which is heating the blast to allow it to heat gas, it may be
necessary to open a supplementary valve or a dust door opening outwards to take
the pressure off the chimney valve, if it is a seat valve, or a slide valve may be
substituted. It may be found in practice that the opening of the chimney valve in
the reversal of the oven which has been heating the blast is unnecessary, then the
reversal can be made by closing the hot blast valve and cold blast valve, opening the
gas valve at the combustion chamber, and then the cold gas valve at the chimney
Bide of the oven.
The following method of working may be used instead of those before described.
Supposing one oven H' is heating the blast the other 15 is being heated, while
the third K³ is heating the gas; then in order to reverse the apparatus, always
commencing with the oven I³, which is being heated in order to always have blast
going to the furnace, I proceed as follows, that is to say, I close the gas supply
valve W connecting with the hot gas main W, and close the valves supplying the
air for combustion and the chimney valve M'; I then open the cold blast valve H¹
and the hot blast valve S, thus causing a current of air to flow through it and
furnishing a highly heated blast; then in the other oven H through which air is
passing I close the hot blast valve S, and then the cold blast valve H¹, and open
the chimney valve M' to allow the air in the oven to pass out through the chimney;
I then open the gas valve W at the combustion chamber, and after a suitable
interval (so as to allow the air in the oven to be drawn into the chimney and the
oven to be filled with gas in order to avoid the danger of an explosion from the
mixture of air and gas in the oven and hot gas main) I close the chimney valve M¹
and open the cold gas valve R' at the chimney side of the oven, thus having gas
pass through the oven and become highly heated, and then passed into the hot gas
main; then in the other oven Ko heating gas I close the cold supply valve R' at
the chimney side of the oven and open the chimney valve M', and then open the
valves supplying the air necessary for combustion, by which means this oven K
becomes highly heated; then after the oven I which is heating the blast has
parted with its effective heat, or the one K³ which is being heated becomes
sufficiently beated, the apparatus is reversed in the same manner, always com-
mencing with the oven K³ which is being heated, then the one I³, which is heating
the blast, and lastly, reversing the one H heating the combustible gas, thus
producing a more intensely heated blast each reversal.
In changing the oven which is heating the blast to allow it to heat gas the same
precautions should be taken as in the other methods.
In the case of arranging four or more combined blast ovens and gas heaters, or
four or more ordinary regenerative hot blast ovens changed into combined blast
ovens and gas heaters along a common hot gas main, but not directly connected
together, forming couples as before described, the construction is entirely similar to
that shown in Figure 24 for the first case and Figure 25 for the second. In either
case any two may be used as blast ovens, while the others are used as gas heaters,
or only thrée can be used as before described, while the fourth is held in reserve or
may be under repair. The construction, as shewn in Figure 24, in which the gas
is burned with heated air is preferable, for after each reversal hotter gas is burned
with hotter air, thus heating the blast oven and gas beater to a higher temperature,
and after each reversal they furnish hotter air and hotter gas, which when burned
heats the other oven and gas heater hotter yet, and so after each reversal a higher
temperature is developed, which is only limited by the resistance of the refractory
materials, hence the operator has at his command a blast whose temperature he is
enabled to perfectly control by properly proportioning the quantity of gas burned
and blast to be heated in the apparatus.

page_text: Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,
First. In a regenerative hot blast apparatus for heating a blast of air, gases, or
vapours to be applied to metallurgical furnaces, the combination with the principle
ovens for heating the blast, of one or more gas heaters or supplementary ovens for
heating the combustible gas consequent to its production and prior to its being
burned in the principal oven, and the gas heaters, substantially as and for the
purpose set forth.
Second. In a regenerative hot blast apparatus, substantially as described, the
combination with the ovens of one or more gas heaters and a hot air main con-
nected to the said ovens and gas heaters, whereby a forced blast of hot air may be
supplied to the burning gas therein to intensify the combustion and thus heat them
intensely, and also to increase the flow of the products of combustion through
the ovens and gas heater, and thus decrease the chimney draught necessary,
substantially as and for the purpose specified.
Third. In a regenerative hot blast apparatus, substantially as described, the
combination with the ovens of a hot air main connected to the said ovens
whereby a forced blast of hot air may be supplied to the burning gases, to intensify
the combustion therein and intensely heat them, to increase the flow of the
products of combustion, and to lessen the chimney draught necessary, substantially
as and for the purpose specified.
Fourth. In a regenerative hot blast apparatus the combination with the ovens of
the gas heaters and the hot air main and hot gas main connected to the said ovens
and gas heaters, whereby intensely bot combustible gas may be supplied to the
ovens and gas heaters to be burned therein by a forced hot blast to heat the ovens
and gas heaters, substantially as and for the purpose specified.
Fifth. In a regenerative hot blast apparatus the combination with the ovens of
the gas heaters and a hot gas main connected to the said ovens and gas heaters,
whereby intensely heated combustible gases may be supplied to the said ovens and
gas heaters to be burned therein, and thereby intensely heat the said oven, sub-
stantially as and for the purpose specified.
Sixth. In a regenerative hot-blast apparatus the combination with the ovens of the
gas heater and the cold blast gas connection, whereby combustible gas may be
heated and supplied to ovens and gas heaters, and an intensely heated blast
supplied to the furnace, substantially as and for the purpose specified.
Seventh. In a regenerative hot blast apparatus, the combination with the
ovens b, b', and the gas heaters a, a', of the cold gas main t and branches 8, v', v³, and
their valves, the hot gas main e¹, branches f¹, g¹, and their valves, the hot air main ',
and the several connections and their valves, and the smoke main leading to the
chimney d', whereby hot air and gas for combustion may be supplied to the said
gas heaters for burning therein, or combustible gas may be passed through the said
heaters, by which means it is intensely heated prior to passing to the ovens and
gas heaters to be burned therein, substantially as and for the purpose specified.
Eighth. In a regenerative hot blast apparatus, the combination with the
ovens b, b, and gas heaters a, a', of the cold gas main t and branches, the hot gas
main e¹ and branches, the pipes g² and ³, and the pipes m², 3, and their respective
valves, and the main ', whereby an intensely heated blast may be supplied to a
metallurgical furnace, substantially as and for the purpose specified.
Ninth. In a regenerative hot blast apparatus, the combination with the respective
combustion chambers of the ovens b, b', and gas heaters a, a', and the hot air main l¹,
of the perforated air cylinders o³ and blocks 83, within the combustion chamber and
their connecting pipes, having suitable valves whereby a forced blast of hot air
may be supplied to the respective combustion chambers of the ovens and heaters,
substantially as and for the purpose specified.
Tenth. In a regenerative hot blast apparatus, the combination with the ovens b, b¹,
and the hot air main l, or parts in free communication with it, of the perforated

page_text: air cylinders o* and blocks 82, within the combustion chambers and their
connecting pipes p, t, provided with suitable valves, substantially as and for the
purpose specified.
Eleventh. The herein described rectangular ovens and gas heaters, each divided
into two parts, forming respectively combustion chambers and regenerators, the
former being equal, in length to the greatest width of the ovens or gas heaters, and
which ovens or gas heaters are also divided into independent compartments, the
regenerator portions of the said compartiments being provided with vertical flues
arranged in sets, forming a decreasing series from the combustion chambers to the
cool end of the ovens or gas heaters, whereby the products of combustion and the
blast or gas to be heated are evenly distributed, and the capacity of each set of
flues, surfaces, and materials are proportioned to the decreasing volume of the
cooling and contracting products of combustion when the ovens or gas heaters are
being heated; and conversely when the ovens or gas heaters are heating the blast or
gas, the capacity of each set of flues, surfaces, and materials are proportioned to
the increasing volume of the blast or gas as it becomes heated, thus producing a
uniform velocity throughout the ovens or gas heaters in each case and very greatly
increasing the efficiency of the apparatus, substantially as set forth.
Twelfth. The combustion chambers of the ovens and gas heaters, having the
lower parts connected by walls, and in which are placed at their angles the
perforated air blocks 83, and at the same level the perforated central air cylinders o³,
substantially as described.
Thirteenth. The valve and stem, formed in one piece and having a continuous
iron pipe embedded therein for the purpose of cooling the valve and to facilitate
the removal of mud or foreign matter deposited by the water, substantially as
described.
Fourteenth. The slide or sluice valve, having the seat formed in one piece and
provided with lugs or projections for fastening it to the casing, and which is
provided with an embedded spiral wrought iron pipe, substantially as and for the
purpose set forth.
Fifteenth. The generative hot blast oven, having at the hot or combustion
chamber side hot blast and hot gas connections for the delivery of a highly heated
gas which has been heated by the said oven and at the same side, the connections
for the supply of the necessary hot or cold combustible gas and hot or cold air
for burning it therein to heat the oven, and having at the cool or chimney'side the
cold air and vapour and gas connections for the supply of cold air and vapour and
gas respectively when being heated by the oven, and also the chimney connection
for the exit of the products of combustion, substantially as described, whereby
highly heated gas or a blast of highly heated air, or a mixture of air and vapour
may be obtained.
Sixteenth. The combination with a regenerative hot-blast oven or gas heater of
the cold gas main W³, connections L', and valve R', the chimney valve M¹, the
distributing main G', and connections F, the cold blast main 0³, and valve H', the
vapour pipe J2, the valve K³, and the branches L at the cool or chimney side, and
at the hot or combustion chamber side the connections I, and the distributing
main O, the dividing strips P, the pipe Q and valve C₁, the pipe Pl and the
valve Q, the gas main W and valves WI, W³, the pipe R and valve S, the
branch T and hot blast main B¹, the pipe K, valve L, branches J¹ and valves M,
the pipes N and valve O', the pipe A¹, the pipe Q, and the valve P3, substantially
as described, whereby highly heated gas or a highly heated blast of air or a mixture
of air and vapour may be obtained at will, as specified.
Seventeenth. The combination of one or more combined regenerative hot-blast
ovens or gas heaters used for heating the combustible gas prior to its being burned
to beat the apparatus with, one or more similar combined or ordinary regenerative
hot blast ovens used to heat the blast, whereby a highly heated blast may be
supplied to a metallurgical furnace, as specified.

page_text: Eighteenth. The regenerative hot blast oven in which the flues in the compart-
ments are arranged in one set, and having walls constructed of ordinary fire bricks
or similar shaped blocks of fire bricks, or other refractory materials whose
dimensions vary with the temperature to which they are exposed and the
temperature of the blast desired, and which are laid diagonally and in reverse
directions in adjacent courses, whereby the effects of expansion and contraction are
effectually provided against and the efficiency of the apparatus greatly increased,
substantially as specified.
Nineteenth. In a regenerative hot blast oven, the combustion chamber divided
into single or double compartments, each having a gas supply connection and air
supply blocks or cylinders placed in the side and partition walls and extending
through the casing, whereby a more equal heating of the apparatus is effected and
repairs are greatly facilitated, as specified.
Twentieth. The combination with a regenerative hot blast oven or gas heater
of the cold gas main W³, pipes L', and valve R', the distributing main G¹, the
chimney valve M¹, the cold blast main 02, and valve H¹, the vapour pipe J³,
valve K³, and branches L³, and the connections F', whereby the gas or blast to be
heated is equally distributed and the efficiency of the apparatus greatly increased,
as specified.
Twenty first. The combination with a regenerative hot-blast oven or gas heater
of the distributing maiu O and connections I, the dividing pipe P, the pipes Q, and
valves C¹, the pipes R, the valve S, the gas main W, and valves W¹, W', the
pipe P1, and valves Q1, whereby the combustible gas to be burned in the oven to
heat it is equally distributed, the oven is equally heated, and the efficiency of the
oven is greatly increased.
Twenty second. In a regenerative hot blast apparatus, the combustion chamber C,
the air blocks or cylinder H, pipes J', and valves M, the pipe K, and valve L, the
pipe N, and valve O', the pipe A¹, the pipe Q', and valve P2, and the cold blast
main O, substantially as described, whereby highly heated or cold air may be
supplied for combustion directly from one oven to the others independent of the
hot blast main, as specified.
Twenty-third. In a regenerative hot blast oven, the roof constructed of
rectangular and wedge-shaped blocks resting on the longitudinal partition walls
covered with strips of sheet iron equal in width to the length of the blocks, and
having upturned flanged edges bolted together and held in place by girders
placed transversely to the flanges and fastened to the casing, substantially as
specified.
In witness whereof, I, the said Henry Harris Lake, have hereunto set my
hand and seal, this Eighteenth day of April, in the year of our Lord
One thousand eight hundred and eighty two.