IMPROVEMENTS IN HOT BLAST OVENS OR FURNACES FOR HEATING AIR
Year: 1880

page_text: LETTERS PATENT to George Barker, of Birmingham, in the County of Warwick,
Consulting Engineer and Patent Ageut, for an Invention of "IMPROVEMENTS
IN HOT BLAST OVENS OR FURNACES FOR HEATING AIR." A communication
from abroad by Horace L. Brooke, of Baltimore, United States of America.
PROVISIONAL SPECIFICATION left by the said George Barker at the Office
of the Commissioners of Patents on the 22nd March 1880.
GEORGE BARKER, of Birminghain, in the County of Warwick, Consulting
Engineer and Patent Agent. "IMPROVEMENTS IN HOT BLAST OVENS OR FURNACES
FOR HEATING AIR." [A communication from abroad by Horace L. Brooke, of
Baltimore, United States of America.]
My Invention relates to that class of devices in use for heating a current of air,
which is then led into a blast furnace, charcoal kiln, or convertor, and it has for its
object to furnish such a device in which facility is afforded for renewing worn out
parts, and by means of which a maximum temperature of blast is secured.
The walls of the oven are constructed with suitable masonry and lined in the
exposed parts with fire brick. A fire place is provided with an arched roof,
through which I form a series of openings extending completely across the oven,
and on each side each opening is a bridge wall extending some distance above the
inner floor of the oven. On one side of the oven, at the top, is the inlet inain, from
which a series of short pipes project communicating with the transverse mains,
which are provided with removable covers, and are square or rectangular in cross
section. Dampers in the mains direct the incoming blast into the downtake pipes,
which latter communicate with the lower transverse mains. Between the before-
mentioned upper and lower transverse mains extend the vertical pipes; all these
pipes (indeed, by preference, all the pipes) are of wrought iron instead of cast iron,
the material hitherto used for this purpose, a feature that will be hereinafter more
particularly referred to.
The lower mains lie between the bridge walls and are provided with thimbles or
spigots, over which the lower ends of the vertical pipes fit, where they are secured
by cross pins which sustain the mains. At their upper ends the vertical pipes
project through holes in the mains, and are retained by pins which pass through

page_text: them. The top of the transverse mains being removable ready access is afforded
for calking the joints between the vertical pipes and the upper mains.
The attachment to the downtake pipes is somewhat different; they are attached
at their lower ends to the pipes or mains in a manner similar to that of the before-
mentioned vertical pipes, but at their upper ends they telescope on spigots, or in
sockets, or thimbles in the mains. The object of this is to provide a slip joint to
allow for unequal expansion.
When it is desired to limit the current or blast in the vertical pipes I use an
internal throttling thimble or neck piece in their upper ends.
The operation of the device is as follows:-Fire being kindled on the hearth or
fire place the heat and flames enter into the oven through the openings and sweep
over the system of pipes. The blast from the main descends through the outside
pipes into the lower mains, and rises therefrom through the series of vertical pipes
into the upper mains, finally finding egress through the incline and delivery pipe.
In structures of this class a great obstacle has hitherto been met. with in the
warping and bending of the cast iron pipes, arising in all probability from unequal
density of opposite sides of the pipes and from unequal expansion, as one side is
heated more than the other.
I obviate this evil and at the same time secure important advantages by making
the pipes of wrought iron. The primary cost is of course in excess of that of cast
iron pipes, but experience has shown that the wrought iron pipes are far cheaper in
the end, besides being more efficient and satisfactory in use. From the superior
strength of the material the wrought iron pipes may be made much thinner than
cast iron, and being better conductors of heat a much higher temperature of blast is
secured.
Moreover, the pipes of wrought iron may be made so thin as to expand in
practically right lines even if unequally heated on opposite sides, and, a most
important point, all the pipes expand about equally, the material being homogeneous.
With cast iron pipes this is not the case, the material is not homogeneous, and
besides warping and bending the pipes expand unequally linearly, straining and
bending the junction mains. Any possible unequal expansion is provided against
in the described oven by means of fitting the pipes in the mains, as any pipe
expanding more than the average simply slides its upper end through its aperture
in the main to that extent.
The baffle walls prevent a direct play of the flames on the mains and the junctions
therewith of the vertical pipes. Each main fits snugly between its walls, so that
by no possibility can the pipes bend or bring the mains directly over the openings,
as frequently occurs in hot blast ovens of the ordinary construction.
Aside from the superior efficiency of my oven in actual use, the peculiar
construction secures certain advantages, which must be noted.
The removeable tops of the top mains enables me to readily remove a burnt out
pipe and insert a new one, and the thimbles or throttling neck pieces afford a simple
and ready means of throttling and directing the blast.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Barker in the Great Seal Patent Offico on the 8th September
1880.
GEORGE BARKER, of Birmingham, in the County of Warwick, Consulting
Engineer and Patent Agent. "IMPROVEMENTS IN HOT BLAST OVENS OR FURNACES
FOR HEATING AIR." (A communication from abroad by Horace L. Brooke, of
Baltimore, United States of America.)
My Invention relates to that class of devices in use for heating a current of air,
which is then led into a blast furnace, charcoal kiln, or converter, and it has for its
object to furnish such a device in which facility is afforded for renewing worn out
parts, and by means of which a maximum temperature of blast is secured.
In the accompanying Drawings, Figure 1 is a vertical section on line y, y,
Figure 2.
Figure 2 is a horizontal section on line x, x, Figure 1.
Figure 3 is a vertical section on a larger scale, showing more clearly the
construction of the pipe ends.
A, A, are the walls of the oven constructed of suitable masonry with fire brick
lining, and B is the hearth or fire place. Through the arched roof of the latter are
a series of openings 6 (see Figure 2), extending completely across the oven, and
on each side of each opening b is a bridge wall G extending some distance
above the inner floor of the oven. On one side of the oven, at the top, is the inlet
main a, from which a series of short pipes that communicato with the transverse
main C, which are provided with removable covers c', and are square or rectangular
in cross section. Dampers c in the mains C direct the incoming blast into the
downtake pipes E, which latter communicates with the lower transverse mains F.
Between the mains C and F extend the pipes d, d. All the vertical pipes (indeed,
by preference, all the pipes) are of wrought iron instead of cast iron, the material
heretofore used for this purpose, a feature that will be hereinafter more particularly
referred to.
The lower mains F lio between the bridge walls G. The mains are provided
with thimbles h, over which the lower ends of the tubes d fit (see Figure 3) and
are secured by pins i, whereby the mains are sustained by the pipes d. At their
upper ends the pipes d, d, project through holes in the mains C, being retained by
means of pins e passing through the pipes. The top c¹ of the main C being removable,
ready access is afforded for calking the joints between the pipes & and the C.
The attachment of the downtake pipes E is somewhat different; they aro
attached at their lower ends to the pipes or mains F in a manner similar to that of
the pipes d; but at their upper ends they telescope on thimbles f in the mains C.
The object of this is to provido a slip joint to allow for unequal expansion. In
Figure 3 is shown a throttling thimble H in the upper end of the pipe; these are
used when it is desired to limit the current or blast. The operation of the device
is as follows:-Fire being kindled in the hearth B the licat and flames enter into
the oven through the openings b, b, and sweep over the system of pipes. The blast
from the main a descends through the outside pipes E into the lower mains F, and
rises therefrom through the pipes & into the mains C, finally finding egress through
the incline a' and delivery pipe. In structures of this class a great obstacle has
heretofore been met in the warping and bonding of the cast iron pipes, arising in
all probability from unequal density of opposite sides of the pipes, and from unequal

page_text: expansion, as one side is heated more than another. I obviate this evil and at the
same time secure important advantages by making the pipes of wrought iron. The
primary cost is of course in excess of that of cast iron pipes, but experience has
shown that the wrought iron are far cheaper in the end, besides being more
efficient and satisfactory in use. From the superior strength of the material the
wrought iron pipes may be made much thinner than the cast iron, and being better
conductors of heat a much bigher temperature of blast is secured. Moreover, the
pipes of wrought iron may be made so thin as to expand in practically right lines
even if unequally heated on opposite sides, and, a most important point, all the pipes
expand about equally, the material being homogeneous. With cast iron pipes this
is not the case, the material is not homogeneous, and besides warping and bending
the pipes expand unequally linealy, straining and bending the junction mains.
Any possible unequal expansions are provided against in the described oven by
means of fitting the pipes in the mains C, as any pipe expanding more than the
average simply slides its upper end through its aperture in the mains C to that
extent. The baffle walls G prevent a direct play of the flames on the mains F and
the junction therewith of the pipes d. Each main F fits snugly between its walls G,
so that by no possibility can the pipes bend or bring the mains F directly over the
openings 6, as frequently occurs in hot blast ovens of ordinary construction. Aside
from the superior efficiency of my oven in actual use the peculiar construction
secures certain advantages which must be noted. The removable tops of the
and
main Cenables one to readily remove a burnt out pipe and insert a new one,
the thimbles or throttling neck pieces H" afford a simple and ready means of
throttling and directing the blast.
Having now described the way in which my Invention is carried into practice, I
would have it clearly understood that I claim the following particular points as part
of my herein before described improvements in hot blast ovens, that is to say,—
1. The combination in a hot-blast-oven of inlet and outlet mains and a series of
pipes uniting the same, and having slip-joints with one of the mains described.
2. In a hot-blast-oven, and in combination with a transverse main, a series of
wrought iron pipes depending therefrom and supporting a common lower main, the
said pipes having slip-joints with the upper main, as set forth.
3. In a hot-blast-oven, a double series of transverse upper and lower mains
united by heating pipes and by pipes for the cold incoming air, which latter are
provided with sliding joints, as set forth.
4. The combination in a hot-blast-oven of the cold air downtake having telescopic
joint, the upper transverse main, and lower main F, the latter being suspended
by pipes & having slip-joints with the upper mains, as described.
5. The combination in a hot-blast-oven of a cold air down take and a main
provided with a series of throttled up-takes, as described.
6. In a hot-blast-oven, an upper and a lower series of transverse mains united by
pipes for the ascending blast, and by pipes for the incoming descending current, as
described.
7. In a hot-blast-oven, an upper transverse main provided with a series of
depending pipes and are movable cover, as set forth.
8. In combination with mains a, c, f, a', the pipes F and d having expansion
joints, as described.
9. In combination with pipes a, the main c having damper c' and removable
top c, as described.
10. In combination with upper mains, the heating pipes & passing freely through
apertures in the lower side of the mains, as described.
11. In combination with the mains ƒ having nipples h, the pipes d and pins i, as
described.

page_text: 12. In combination with the mains c and f, the pipes & sustaining the lower
mains and free to expand independently of cach other.
13. In combination with the pipes d, the throttling thimbles H, as set forth.
In witness whereof, I, the said George Barker, have hereunto set my hand
and seal, this Nineteenth day of August, in the year of our Lord One
thousand eight hundred and eighty.
Witnessed by
JOSEPH HENRY PEARSON,
Clerk to George Barker,
Consulting Engineer & Patent Agent,
77, Colmore Row,
19th day of August, 1880.
Birmingham.
GEORGE BARKER. (L.S.)