IMPROVEMENTS IN THE CON- STRUCTION OF GAS FURNACES
Year: 1876

page_text: LETTERS PATENT to William Anderson, of Southwark Street, in the Borough
of Southwark, Engineer, for the Invention of "IMPROVEMENTS IN THE CON-
STRUCTION OF GAS FURNACES." A communication from abroad by Demetri
Chernoff, of Alexandroffsky, near St. Petersburg, in the Empire of Russia.
PROVISIONAL SPECIFICATION left by the said William Anderson at the
Office of the Commissioners of Patents on the 16th June 1876.
WILLIAM ANDERSON, of Southwark Street, in the Borough of Southwark, Engineer.
"IMPROVEMENTS IN THE CONSTRUCTION OF GAS FURNACES."
Siemens' regenerative furnaces are constructed with the object of utilizing the
heat which would otherwise escape up the chimney, but as this heat can for the
most part be used in raising steam, the system does not produce a real economy
of fuel. The system, however, has rendered good service by enabling very high
temperatures to be obtained in furnaces, and a furnace (without a regenerator) for
working iron and steel would now be considered imperfect.
The objections to Siemens' furnaces are, 1, great cost; 2, they take up a great
deal of space; 3, they require a great deal. of heat to warm up the immense mass
of brickwork; 4, every half hour when the valves are reversed a large quantity
of gas escapes into the chimney.
The object of the present Invention is to utilize heat from a different source, and
which has hitherto always been wasted in Siemens' furnaces, namely, the heat
escaping by radiation through the walls of the furnace. This loss by radiation
is not less than that which escapes by the chimney. The loss of heat required to
produce a draught in the furnace must always exist, no matter what system
is adopted.
Another defect of the Siemens' system is the ease with which the bricks melt,
the best silica bricks seldom stand 30 heats, they melt down to 2 inches thick and
then fall in.
These are the reasons that render it desirable to save heat from the coals, and
still make use of the heat from the flue for getting up steam. Such a system must
result in great economy, bringing it near the theoretical quantity necessary.
The greatest heat of a furnace is over the grate when the burning is most
energetic. The advantage of a gas furnace among others consists in this, that the
Price 6d.1

page_text: hearth coincides with the grate, the dimensions of the former depending on the size
of the material worked, and also on the space required for the mixture and com-
bustion of the gases. The gas furnaces may be used for melting any kind of
material, the size depending on the quantity to be worked at one time, and it may
have a moveable hearth or a fixed one. The hearth may be covered in either with
a cylindrical or hemispherical or domed arch. The gas and air necessary for
combustion are introduced through the walls and roof of the furnace through small
orifices made through the bricks of which they are built. The roof is built on
foundation beams of bricks which rest on cast-iron columns, and their ends are
bolted to standards supporting the cast-iron end plates of the furnace.
The bricks must be made accurately to form, of good fire-clay, and are laid dry,
openings are provided to receive perforated bricks, which have much the same
appearance as the perforated tiles of the Bessemer apparatus. Besides the one
large centre hole these perforated bricks have a number of /in. to 1/2in. perforations
or narrow channels. When the brick arch has been turned a cast-iron arch is
erected over it. This arch has round openings corresponding to the openings in
the bricks, and through them are set in clay hollow bricks, or tiles, or twyers, just
as they are fixed in the Bessemer' converters. These hollow bricks or tiles do not
fit closely but have a freedom of from 3/in. to 1/in. which gets over any want of
accuracy in the work, and also compensates for settlement or any expansion due
to the heat; besides this freedom is necessary for the regenerators. To the ends of
the arch are secured an end plate, provided with apertures for letting in the air
between the iron and brick arches. After the hollow twyere bricks have been
placed the iron arch is covered by a casing of light corrugated iron, and by this
means are formed air chambers which are separated from each other but each
connected with the furnace space by small tubes and by the freedom of fit between
the bricks. To prevent end strain the sections of the arches do not touch each
other, but the joint is made good by iron bands placed in suitable recesses and
packed with tarred yarn. The front end of the furnace with the working orifice
and the flue for taking off the products of combustion are constructed in the
same manner, only the bricks will not be taper and the iron plates will not be
arched. There will be no occasion to allow for expansion in the end plates, and the
joint between the arches and the end plates will simply be built upon brickwork
and filled up with sand.
Gas from the producers is admitted into the external chambers beneath the
corrugated iron cover and passes through the perforations in the twyere bricks
into the furnace and there burns, with the addition of the air from the air chambers
penetrating through the pores and the spaces between the bricks. If the arch is
low and the draught light, then the flame will beat direct on the object placed
on the hearth, that is, exactly on the spot where the most heat is required, and
where the act of combustion will be most energetic. When the furnace is lighted
the heating of the internal lining commences at once, and with it the increase of
temperature of the entering air and gas, till such time as a balance is established
between the conducting powers of the walls and the quantity of heat taken up by
the air and gas passing through the bricks, and then they will enter at the same
temperature as in the Siemens' furnaces. The bricks will not melt in consequence
of being kept cool by the air and gas passing through them, and there will only be
loss of heat through the hearth, which cannot very well be avoided. The rest of
the heat will all be employed usefully in melting the metal, and in heating steam
boilers. The greater or less degree of regenerations depends on the thickness
of the walls or the length of the tubes, and the speed at which the gas and air pass,
also on the relation between the surface area of the tubes and the mass or weight
of brickwork. The longer the tubes or thicker the walls the more numerous
the tubes are and greater the surface area to the mass of brick, and the larger
the quantity or the greater the speed of gas and air the more perfect will be the
regeneration.
This improved system of constructing gas furnaces admits of many modifications.

page_text: For example, the sides and lower part of the arches may have gas only going
through them, and the upper part of the roof may have air only, then there will be
no occasion to have iron arches or the twyere bricks, but the whole structure will
be composed of porous bricks which will be safer and cheaper. The air will fall
like rain on the entering gas and will mix with it very well, only two gas passages
will be required, as the air will be drawn in from the atmosphere. If artificial
pressure of the air is necessary a sheet-iron cover can be fitted to the air chamber.
Again, the gas and the air bricks may be arranged in belts, the air bricks may
be either wider than the gas ones or pierced more numerously with holes. Or the
air and the gas bricks may be laid in alternate longitudinal layers.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Anderson in the Great Seal Patent Office on the 16th
December 1876.
WILLIAM ANDERSON, of Southwark Street, in the Borough of Southwark, Engineer.
"IMPROVEMENTS IN THE CONSTRUCTION OF GAS FURNACES." A communication
from abroad by Demetri Chernoff, of Alexandroffsky, near St. Petersburg, in the
Empire of Russia.
Siemens regenerative furnaces are constructed with the object of utilizing the
heat which would otherwise escape up the chimney, but as this heat can for the
most part be used in raising steam, the system does not produce a real economy of
fuel. The system, however, has rendered great service by enabling very high
temperatures to be obtained in furnaces, and a furnace (without a regenerator) for
working iron and steel would now be considered imperfect.
The objections to Siemens' furnace are, (1) great cost, (2) they take up a great
deal of space, (3) they require a great deal of heat to warm up the immense mass of
brickwork, (4) every half hour when the valves are reversed a large quantity of
gas escapes into the chimney.
The object of the present Invention of improvements in the construction of gas
furnaces is to utilize heat from a different source, and which has hitherto always
been wasted in Siemens' furnaces, namely, the heat escaping by radiation through
the walls of the furnace. This loss by radiation is not less than that which escapes
by the chimney. The loss of heat required to produce a draught in the furnace
must always exist no matter what system is adopted.
Another defect of the Siemens' system is the case with which the bricks melt,
the best silica bricks seldom stand thirty heats, and they melt down to two inches
thick and then fall in.
These are the reasons that render it desirable to save heat from the walls and
still make use of the heat from the flue for getting up steam. Such a system must
result in great economy, bringing it near the theoretical quantity necessary.
The greatest heat of a furnace is over the grate, where the burning is most
energetic. One of the advantages of a gas furnace consists in this, that the hearth
coincides with the grate, the dimensions of the former depending on the size of the
material worked, and also on the space required for the mixture and combustion of
the gases. The gas furnaces may be used for melting any kind of material, the
sizo depending on the quantity to be worked at one time, and it may have a
moveable hearth or a fixed one. The hearth may be covered in either with a semi-
cylindrical or with a hemispherical or domed arch. The gas and air necessary for
combustion are introduced through the walls and roof of the furnace through small
orifices made through the bricks of which they are built.
Fig. 1 is a longitudinal vertical section of a gas furnace constructed according to
the present Invention. Fig. 2 is a transverse vertical section of the same. In theso
Figures the hearth is fixed, but if desired it may be made moveable, as shown at
Fig. 3. The upper part of the furnace in this instance is constructed in precisely
the same manner as is shewn in Figures 1 and 2, and therefore the same description

page_text: The roof is built of bricks on
foundation plates A which rest on cast-iron columns B, and their ends are bolted
to standards supporting the cast-iron end plates of the furnace. The bricks a, a, of
which the arched roof is constructed must be made accurately to form, of good fire-
clay, and are laid dry. One of these bricks a is shewn in section and drawn upon
an enlarged scale at Figures 4 and 5, and front elevation at Fig. 6. An opening a¹
is made in the centre to receive perforated bricks b, b, which have much the same
appearance as the perforated tiles of the Bessemer apparatus.
will equally serve for both the arrangements.
Besides the one large central hole to receive the long hollow bricks b, b, these
perforated bricks a, a, have a number of long narrow perforations or channels c, c, c,
Fig. 2, from three-eighths to half an inch in diameter, as seen in Figures 4, 5, and 6.
When the brick arch a, a, a, Figures 1 and 2, has been turned a cast-iron arch D
is erected over it. This arch has round openings corresponding to the openings in
the bricks a, a, and through them are set in clay the long hollow bricks, tiles, or
These hollow
twyeres b, b, just as they are fixed in the Bessemer converters.
bricks or tiles do not necessarily fit closely, but have a freedom of from three-eighths
to half an inch, which gets over any want of accuracy in the work, and also com-
pensates for settlement or any expansion due to the heat, besides this freedom is
necessary for the regeneration.
a, a.
To the ends of the arch a, a, are secured an end plate E, provided with apertures
e for letting in the air to the space g between the iron arch D and the brick arches
After the hollow twyere bricks b, b, have been placed the iron arch D is
covered in by a casing f of light corrugated iron, and by this means are formed the
air chambers g and h, which are separated from each other, but are each connected
with the interior of the furnace space by the small holes or perforations in the
bricks a and b, and by the freedom of fit between the bricks.
To prevent end strain the sections of the cast-iron arches do not touch each other,
but the joint is made good by iron bands or hoops placed in suitable recesses d,
Fig. 1, and packed with tarred yarn or other suitable packing.
The ends of the furnace with the working orifice and the flue for taking off the
products of combustion are constructed in the same manner, except that the bricks
will not be taper and the iron plates d and f will not be arched. There will be
no occasion to allow for expansion in the end plates, and the joint between the arches
and the end plates will simply be built upon brickwork and filled up with sand.
Gas from the producers is admitted into the external chambers or spaces beneath
the corrugated iron cover f and passes through the perforations in the twyere
bricks b, b, into the interior of the furnace and there burns with the addition of
the air from the air chambers or spaces g, which air will penetrate through the
perforations and the spaces between the bricks a, a.
If the arch is low and the draught light, then the flames will beat direct on the
object placed on the hearth, that is, exactly on the spot where the most heat is
required, and where the act of combustion will be most energetic. When the
furnace is lighted the heating of the internal lining commences at once, and with it
the increase of temperature of the entering air and gas, till such time as a balance
is established between the conducting powers of the walls and the quantity of heat
taken up by the air and gas passing through the bricks, and then they will enter
at the same temperature as in the Siemens' furnaces. The bricks will not melt as
they will be kept cool, by the air and gas passing through them, and there will only
be loss of heat through the hearth, which cannot very well be avoided. The rest
of the heat will all be employed usefully in melting the metal and in heating steam
boilers. The greater or less degree of regeneration depends on the thickness of
the walls or the length of the tubes and the speed at which the gas and air
pass, also on the relation between the surface area of the tubes and the mass or
weight of brickwork. The longer the tubes or thicker the walls the more numerous
the tubes are and greater their surface area to the mass of brick, and the larger
the quantity or the greater the speed of gas and air the more perfect will be the
regeneration.

page_text: It is necessary to pay attention to the fact that the draught of the chimney must
be greater than the upward pressure of the heated gases in the furnace itself, i.e.,
if the internal pressure in the furnace is greater than the external pressure then
the air will not come in through the upper orifices in the roof; but with low roofs
(and there is no occasion for high ones) the draught of a chimney fifty or sixty
feet high will be sufficient to draw in air and cause it to mix with the combustible
gases.
The furnace will be started in the following manner :-The chimney being
warmed to create a draught a fire is to be lighted on the hearth, the air passages
being all open. As soon as the brickwork is well warmed the gas is to be turned
on and it at once begins to burn. The influx of the gas and air are regulated by
suitable valves. To stop the furnace it is only necessary to shut off the gas and
allow the current of air to enter till the furnace becomes quite cold. The current
of external air by passing over the surface of the iron arches will prevent them
from getting hot.
This improved system of constructing gas furnaces admits of many modifications.
For example, the sides and lower parts of the arches may have gas only going
through them, and the upper part of the roof may have air only, then there will
be no occasion to have iron arches or the twyere bricks, but the whole structure
will be composed of porous bricks, which will be safer and cheaper in construction
than the arrangement just described and shewn in Figures 1 and 2. An arrange-
ment of this kind is shewn at Fig. 7, in which it will be seen that the space above
the arch made of the perforated bricks a, a, is divided into compartments, two of
which are supplied with combustible gas, and the other one with air. The air
from the compartment g will fall like rain on the gas entering from the com-
partments h, h, and will mix with it very well; only two passages will be required
to supply the gas to the compartments h, h, as the air will be drawn in from the
atmosphere. If artificial pressure of the air is necessary a sheet iron cover can
be fitted to the air chamber, as shewn in the Drawing.
As a modification of the above the gas and the air bricks may be arranged in alter-
nate belts, as shewn at Figures 8 and 9. Fig. 8 being a transverse vertical section, and
Fig. 9 a longitudinal section of the roof of a furnace constructed in this manner.
The air bricks a, a, may be either wider than the gas ones b, b, or they may be pierced
more numerously with holes.
As a further modification the air and the gas bricks may be laid in alternate
longitudinal parallel lines, as shewn in Fig. 10, a, a, being the bricks for admitting
air from the external atmosphere, and b, b, the bricks for supplying the gas which
has been admitted to the long spaces or chambers h, h.
In adapting the Invention to a furnace for melting steel or other metal in
crucibles, the principle of construction is precisely the saine as that shewn at
Figures 1 and 2, but the form of the furnace is of course very different in appearance.
In Sheet II., Figures 11 and 12, are two vertical sections of a furnace for melting
metal in crucibles, the two sections being taken in lines at right angles to each
other; Fig. 13 is a horizontal section of the same; and Fig. 14 is a plan or top
view of the furnace. It will be seen that the sides of the furnace are constructed
of perforated bricks which are arranged in four horizontal series, two of which
communicate with the conduits h, h, which supply the gas, while the other two
series are in connection with the air passages J, J. It will be seen that the interior
of the furnace is perforated on all sides, and that the mixed gases will play upon
the sides of the crucible which stands as usual on a block at the bottom of the
furnace in which are made holes i, i, Fig. 13, for the escape of any molten metal
should a crucible accidentally break when charged with molten metal.
The unconsumed gases or gaseous products of combustion pass from the combustion
chamber along the flue j, at the top of which is made an opening to introduce and
withdraw the crucible, and this opening is closed by a cover in which are made
peep holes for the purpose of inspecting the interior of the furnace. These holes
may be stoped with fire-clay when not required for use.

page_text: Having now described the Invention which has been communicated to me by
my foreign correspondent, and having explained the manner of carrying the same
into effect, I claim, as the Invention secured to me by Letters Patent as aforesaid,
constructing gas furnaces with perforated bricks, tiles, or other equivalent devices,
so arranged that part of such perforated bricks or their equivalents may be in
connection with a space or chamber supplied with combustible gas, while the
remainder of such perforated bricks or their equivalents are in connection with the
external air or with an air blast, as and for the purposes herein set forth.
In witness whereof, I, the said William Anderson, have hereunto set my
hand and seal, this Fifteenth day of December, in the year of our Lord
One thousand eight hundred and seventy-six.
W. ANDERSON. (L.S.)
(12.5.)