Improvements in Regenerative Hot-blast Stoves.
Year: 1892

page_text: Date of Application, 1st Mar., 1892-Accepted, 2nd Apr., 1892
COMPLETE SPECIFICATION.
[Communicated from abroad by GEORGE WASHINGTON MCCLURE and CARL
AMSLER, both of Pittsburgh, United States of America, Metallurgical
Engineers!
處
Improvements in Regenerative Hot-blast Stoves.
I JAMES JOHNSON of 4 Clayton Square Liverpool in the County of Lancaster
Patent Agent, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
Fig. 1 shows in vertical central section the upper part or dome and the lower
part of my improved hot blast stove. The part of this figure at the lower right-
hand corner is in section on the line X-X of Fig. 2. Fig. 2 is a horizontal
sectional view in four different section planes, viz., on the planes shown by the
lines A-A, B-B, C-C and D-D, respectively.
The object of my invention is to provide a stove having at the top a connection
between the vertical flues and the stack flue, so constructed that there shall not be
that liability to fracture of the walls by expansion and contraction which has been
present in stoves constructed as heretoforc. This we effect by constituting the
connecting passage by means of a dome, shell, or arch, made separate from the
crown of the stove and affording an intervening space instead of forming flues in
the crown itself. Our invention also relates to other features of construction of the
stove.
Referring now to the drawings, 2 represents the outer cylindrical wall of the
stove encased in a suitable jacket. The stove as shown is divided into a series of
concentric annular flues; though it should be understood, that my invention broadly
stated, is not limited to the arrangement of such flues, since the construction of the
top of the stove is claimed by me independently. I intend also to claim these
features in combination.
3 is the central flue of the stove, the base of which serves as the combustion-
chamber, while the upper part terminates below the stove crown 4 and communicates
with an annular flue 5, formed by an outer cylindrical wall 6, which extends from
the crown to the stove's base. 7 is an outer due constituted by the annular space
intervening between the walls 6 and 2. The flue 5 is divided into a number of
parts by radial partition-walls 8, which serve to increase the heating surface of the
stove, and the Huc 7 is also divided by an annular wall 9, and cross partitions 10.
The flues 5 and 7 are connected by ports 11 at the lower part of the stove. These
ports 11 enter the middle of the flucs, and in addition thereto there are other
connecting ports 111 at the sides of the ports 11 which ensure even flow of the gas
All the radial
to all parts of the flue and prevent unequal distribution of the gas.
walls in the outer flue 7, terminate above the level of the ports so as to afford an
open continuous flue-chamber at the base of said flue.
12 is a gas inlet port opening into the base of the flue 3. 13 is a gas-burner pipe
adapted to discharge gas thereinto; and 14 is an air inlet port through which air is
admitted to support combustion of the gas. 15 is the hot-blast main provided with
a suitable valve 16 and leading from the base of the flue 3.
This main is also
provided with an air-port 17 for the inlet of air to assist in combustion of the gas..
18 is a dome or arch which surmounts the outer wall 2 and is separate from the
crown of the stove so as to afford an intermediate flue or passage 22 connecting.all
the divisions of the outer flue 7 with a central stack flue 19 for the exit of the
products of combustion. 20 is a valve for closing the stack-flue and 21' is the cold
blast inlet pipe, which discharges into the stack flue below said valve and is itself
provided with a suitable controlling valve by which the admission of air may be

page_text: regulated. 21, 21, are holes through which may be drawn chains attached to
suitable brushes or scrapers in the flues.
The operation of the stove is as follows:-To heat the flues, the stack flue 20 is
opened, the valve of the hot blast main is closed, and combustible gas is introduced
into the gas inlet 12. The gas uniting with air admitted through the air-inlets
burns in the flue 3, ascends through this flue to the crown of the stove, then
descends through the several divisions of the annular flue 5, and at the base thereof
passes through the ports 11 and 11' into the outer flue 7 and ascends through the
divisions of this flue and finally passes through the flue 22 to the stack. When the
Anes have been heated in this manner to a sufficiently high degree, as in ordinary
hot blast stove practice, the gas and air inlets into the base of the flue 3 are closed,
the stack valve 20 is also closed, and the valves of the cold blast pipe and hot blast
main are opened. The air then enters through the cold blast main, descends through
the flue 22, and passes in succession (and in reverse direction to the above described
course of the gases of combustion) through the flues 7, 5 and 3, in which it is heated
by the stored heat of the walls, and finally passes off through the hot blast main to
the furnace at which it is utilized. When the stove has cooled to such extent that
the air is no longer efficiently heated, it is again heated by reversal of the valves
in the usual way.
It will be noticed from the foregoing description that the arch 18 being not tied
to the inner crown of the stove is quite free to move vertically with the outer walls
in the expansion and contraction caused by variations in temperature of the stove.
In this way I overcome what has been a fruitful source of injury to the masonry of
the stove structure. Another advantage which results from having the flue 22
continuous or practically so, instead of employing a series of small individual flues
traversing the furnace crown, is that I secure an even draft from all the divisions
of the upright flues, and thus improve the stove in respect of evenness of heating
and efficiency.
Modifications in the construction of the stove will be suggested to those skilled
in the art.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
First. A. hot blast stove comprising an outer roofed shell, an inner shell having a
crown separated from the outer roof, valved passages leading into the inner shell,
and valved passages leading from the space between the roof and crown; sub-
stantially as and for the purposes described.
Second. A hot blast stove comprising an outer roofed shell, an inner concentric
shell with a crown and having apertures in its sides, an open topped shell within
the inner crowned shell, valved passages leading into the innermost shell, and
valved passages leading from the space between the roof and crown; substantially
as and for the purposes described.
Third. A hot blast stove, comprising an outer roofed shell, an inner shell having
a crown, a series of apertures in the lower part of the inner shell, a higher series of
apertures alternating therewith, valved passages leading into the inner shell, and
valved passages leading from the space between the roof and crown; substantially
as and for the purposes described.
Fourth. A hot blast stove, comprising an outer roofed shell, an inner apertured
shell having a crown separated from the outer roof, partitions in the flue between
the shells and terminating above the apertures, valved passages leading into the
inner shell, and valved passages leading from the space between the roof and
crown; substantially as and for the purposes described.
Fifth. A hot blast stove, comprising an outer roofed shell, a valved stack flue
leading therefrom, an inner concentric shell having a separate crown, apertures in
the wall of the inner shell, a combustion chamber within the inner shell, a hot
blast outlet, and combustible gas inlet, leading thereto, and a cold blast outlet

page_text: terminating in the space between the crown and roof; substantially as and for the
purposes described.
Sixth. A hot blast stove, having annular shells therein, provided with passages,
and partitions terminating above the passages; substantially as described.
Dated the 29th day of February 1892.
J. JOHNSON.