Improvements in Hot Blast Stoves..
Year: 1892

page_text: Date of Application, 1st Mar., 1892—Accepted, 2nd Apr., 1342
COMPLETE SPECIFICATION.
[Communicated from abroad by GEORGE WASHINGTON MCCLURE, of Pittsburgh,
Pennsylvania, United States of America, Metallurgical Engineer.]
Improvements in Hot Blast Stoves..
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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 :-
Figure 1 is a vertical central sectional view of my improved hot blast stovė.
Fig. 2 is a view shewing the same in horizontal section on the line I-II of.
Figure 1.
Fig. 2 is a section taken on the line X-X of Fig. 2.
Fig. 3 is a view, one half of which shows in plan view the top of the stove, while
the other half shows it in transverse section on the line 111-III of Fig. 1.
Fig. 3 is a section on the line Z-% of Fig. 1.
Fig. 4 is an enlarged vertical section of one side of the stove taken through one
of the bottom doors on the line IV-IV of Fig. 5.
Fig. 5 is a horizontal cross section on the line V-V of Fig. 4.
Like symbols of reference indicate like parts in each.
As shown in the drawings, the stove has a central combustion chamber, a central
vertical flue, which forms the first pass for the gas by which the stove is heated, and
vertical flues arranged outside the central flue through which the gas passes in its
course through the stove.
2 is the combustion chamber, 3 is the traverse flue, through which gas is admitted
to the combustion chamber. 4 is the flue through which air is admitted to burn
with the gas, and 5 is the vertical flue forming the first pass for the burning gas.
This flue is preferably circular in cross section, and extends nearly to the crown or
arch 6. 7, 7, are vertical flues communicating at the top with the space 8 under
the crown, and extending downwardly exterior to the walls of the flue 5. The
conjoined flues 7 form an annular space within the stove, which is separated into
individual flues by radial walls 9 extending to the bottom of the stove. Outside
the flues 7, is an annular series of flues 10, which communicate at the base with the
flues 7, through ports 11, and which may be divided into two annular divisions by
an upright circular wall 12, which extends to within a short distance of the bottom
of the Hues. The transverse divisions of the flues 10 are formed by radial walls 13.
Some of the walls 9 extend entirely to the bottom of the stove, thus dividing the
fines 7 into parts laterally distinct from each other, which so guide the gas in its
flow, as to prevent it from passing through some of the parts of the stove in
preference to others. At their upper ends the flues 10 are connected with the stack
Hue 14 by transverse flues 15, which extend through the crown of the stove, and are
shown in Figures 1 and 3. 16 is the chimney valve, consisting of a disk supported
by a suitable lever 17 and adapted to fit against the underside of a seat 18 built in
the masonry of the stack. 19 is the cold blast pipe, which enters the stack, and at
its end is upwardly directed towards the underside of the valve 16, so that the
pressure of the blast emerging from the pipe tends to force said valve to its seat.
20 is the hot blast outlet flue which leads from the combustion chamber at the base
of the flue 5 and is provided with a suitable valve 21.
The manner of building the walls of the stove is novel and is illustrated in
Figures 2 and 34. The walls of the flue 5 are built of vertical. brick courses 22
and 23 and at the lower part it may have an interior lining 24. The use of the two
vertical courses of bricks 22 and 23 is desirable in order that each may cover the
vertical joints of the other, and in building the stove I prefer to secure greater

page_text: stability by setting the bricks 22 on the inside and on the outside in alternate
horizontal courses. This is illustrated in Figure 34, in which I show a horizontal
section of the stove taken on two distinct section planes, each half of the view being
taken on a horizontal plane intersecting the next horizontal course of bricks above
or below the plane of the other. As shown in this view and in part of Figure 2,
the outer circular wall of the flue 7 is constituted of vertical courses of wide and
narrower, bricks b and c, which in alternate horizontal courses are set on alternate
sides of the wall. The radial walls 9 are built of bricks which in alternate
horizontal courses are tied to the outer wall of the flue 7, as shown at the left of
Figure 3, and in the intermediate courses are preferably not so tied thereto, but
simply abut against the said wall, covering some of the vertical joints thereof.
The bricks of the walls 9 however are not tied to the inner wall of the flue 7, but
simply abut against the said wall, covering some of the vertical joints thereof.
In like manner the bricks of the radial walls 13, are tied in alternate horizontal
courses to the outer wall of the Aue 10, but simply abut against the inner wall of
the said flue. The stove is encased on the outside in the usual strong metal
jacket 26.
When thus constructed, the walls of the stove may expand and contract vertically
without danger or breaking the other walls, as in stoves in which the flue walls are
fixedly bonded together. Thus, when the central flue wall, being the one most.
subject to heat, expands vertically, it does so independently of the outer circular
wall and flue walls 9, which being bonded together and both subject to about
the same heat, are not bonded to the inner wall. In like manner, the outer circular
wall of the flue 7 and the radial walls 9 expand and contract quite independently of
the outer wall of the stove and walls 13, which though bonded together, are not
fixed to the inner circular wall against which they abut. The stove on the outside
is encased in the usual strong metal jacket 26. This structure is one which is
extremely durable, and is of great advantage in preserving the stove by resisting
the force exerted upon the walls by the expansion caused by the heat of the burning
gases. To a great measure the bricks of each flue are braced by the breaking of
its vertical joints by the bricks of the inner and outer flues, and by the bricks of
the radial walls, so that each flue wall takes up the force exerted on its neighbouring
walls, thus obliging all to expand and contract laterally as a unit. The difficulties
arising from independent lateral expansion and contraction of the flue walls, which
have been such as to cause these walls soon to deteriorate or to collapse, are thus
altogether avoided.
In order to prevent expansion of the stove from injuring the jacket, 1 leave a
small annular space e between the inside of the jacket and the outer surface of the
brick structure of the stove, and a still larger space e¹ between the crown of the
stove and the nuderside of the top of the jacket. These spaces permit the brick-
work to expand freely within the desired limits. In order to provide means for
cleaning the flues, I use vertical pipes 25, extending into the flues from the top of
the stove as shown in Figures 1 and 3. Suitable brushes or scrapers may be
operated by chains introduced into the flue through these pipes. When not in use,
the pipes are closed by suitable caps (not shown).
I shall now describe in general the operation of my improved stove. To heat
the flues preparatory to forcing the blast therethrough, the combustible gas is
admitted at 3 into the combustion chamber, where it combines with air entering the
port 4 and in a state of combustion passes up through the flue 5 to the chamber 8;
thence in its second pass, down through the flues 7, and finally up through the
flues 10 and 15 to the stack flue. The construction of my stove is so perfect that
the heat of the gas is absorbed by the flue-walls and is reduced to a minimum by
the time it reaches the stack. When the stove has been sufficiently heated, the
valves of the parts 3 and 4, and the stack valve 16 are closed, the valve 21 is
opened and the air-blast is admitted to the stove from the pipe 19 and passes
through the flues in a reverse order to that just indicated, and finally emerges in a
superheated state through the flue 20.

page_text: 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. In a hot blast stove, the combination with an upwardly scating stack-
valve of an air-blast-pipe having its end directed towards the underside of the valve,.
and adapted to apply to the valve a scating pressure; substantially as and for the
purposes described.
Second. In a hot blast stove, a vertical central combustion flue having an annular
wall, a surrounding annular wall separated therefrom to afford an interinediate flue
space connected at the top with the combustion-flue subdividing radial walls inter-
posed between the wall of the combustion flue and the outer wall, and being keyed
to one of said walls and abutting against the other, so as to be capable of motion
with its attached wall independently of the other; air and gas inlets for the com-
bustion flue, a hot blast outlet leading from the stove, a cold blast inlet, and a stack
fine, substantially as and for the purposes described.
Third. In a hot blast stove, a vertical central combustion flue having an annular
wall, a surrounding annular wall separated therefrom to afford an intermediate Alue
space connected at the top with the combustion flue subdividing radial walls inter-
posed between the wall of the combustion flue and the outer wall, and being keyed
to one of the said walls and abutting against the other, so as to be capable of motion
with its attached wall independently of the other, a third and outer annular wall,
concentric with the others, and sub-dividing radial walls interposed between the last
named annular wall and the next inner annular wall, keyed to one of the said
walls and abutting against the other; substantially as and for the purposes.
described.
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