Improvements in Hot Blast Stoves.
Year: 1889

page_text: [Communicated from abroad by HUGH KENNEDY, of Sharpsburg, in the County of
Allegheny, and State of Pennsylvania, United States of America.]
Improvements in Hot Blast Stoves.
I JOHN THOMSON KING 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 :-
The invention relates to firebrick hot blast stoves and the object is to cheapen and
simplify their construction to reduce the expense of maintenance and to save manual
labour in their operation.
The efforts of constructors and improvers of hot blast stoves have been largely
directed to economy in gas, the theory being that all the heat possible should be
extracted from the gas before it escapes to the flue. This has led to the devising and
construction of stoves so expensive to erect and maintain that the advantage arising
from their economy in use is nearly if not quite overbalanced thereby. "Practical
experience in blast furnace practise has shown that most of the modern blast furnaces
produce more gas than is necessary for heating the blast and that the excess is allowed
to go to waste. It is therefore unnecessary that the stoves of such furnaces should be
constructed with special reference to economy of gas and the consequence is that
cheaper stoves if capable of heating the air properly will do just as well as those at
present used.
To enable others skilled in the art to make and use the said invention I will now
describe it by reference to the accompanying drawings in which
Fig. 1 is a vertical longitudinal section of a plant of four stoves embodying my
invention on the line AA of fig. 2. Fig. 2 is a horizontal section on the
line BB of fig. 1. Fig. 3 is a vertical cross section on the line C--C of fig.
on
on gas." Fig. 4 is a similar section showing the stoves
showing the stoves
air."
kr
Like figures of reference indicate like parts whereever they occur.
2

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The stoves, of which a plant of four is shown in figs. 1 and 2, are constructed of
firebrick, and have the usual external sheet iron casing, 5. They may be empty
chambers as at 1, or have vertical walls projecting from their inner surface, or be pro-
vided with checker-work, or hollow bricks. In the latter two instances, the filling
should be supported by suitable arches in the usual way to an open chamber at the
bottom. These instances of variation are mere statements as to how the heating
surface in the interior of the stove may be increased if desired, and not given with a
view of claiming such construction, or of limiting the invention to the use of any
particular construction or arrangement of the heating surfaces, as any good and
adequate construction of the same will do. The air inlet, S, is placed at one end of the
row of stoves, and the hot air outlet, 9, at the other end. There is a separate gas
inlet, 10, at or near the base of each stove, and a separate gas outlet, 11, at the top of
each stove. The stoves communicate with each other by opening through the partition
walls. It is necessary that there should be at least two stoves, although as many more
as may be desired may be connected therewith, and the air exit of each should be at
the opposite end from the air inlet. Thus in fig. 1 the air inlet, 8, of the stove, 1, is at
the base, and the air outlet is the opening, 12, by which the stove, 1, communicates
with the stove, 2, and in like manner the outlet of the stove, 2, is at the bottom, being
the opening, 13, by which it communicates with the stove, 3, and the outlet of the
stove, 3, is at the top, being the opening, 14, by which it communicates with the
stove, 4.
The air entering at the inlet, 8, passes alternately up and down, and after
traversing the entire length of each stove, passes out at the outlet, 9, which it will be
understood, is connected with the hot air flue leading to the furnace. The inlet, 8, is
provided with a valve, 15, and the outlet 9, with a valve, 16, so that they can be
closed when the stoves are put on gas." The gas enters each stove at the gas
inlet, 10, near the bottom, and passes directly up through the stove and out through
the gas outlet, 11, at the top of the same. The gas is supplied through the usual gas
flue, 33, (figs. 3 and 4) whence it passes into the stove by means of a pipe, 17, leading
from the flue, 33, up to the gas inlet opening, 10. This pipe, 17, may, if desired, be
fixed, but the construction shown is preferred, in which the upper part, 18, of this pipe
is movable, being secured to a slide, 19, which rests on a bed plate, 20, and is recipro-
cated by means of a rack 21, and pinion, 22. By this construction the horizontal end
of the pipe, 18, can be moved forward into the gas inlet, 10, or drawn backward out
of it. When it is moved forward, its lower end registers with the upper end of the
stationary part of the pipe, 17, and communication is established between the gas
flue, 33, and the stove, as shown in fig. 3, and when the slide, 19, is drawn back, the
pipe, 18, is retracted from the gas inlet and the solid part of the slide covers the upper
opening of the pipe, 17, thereby acting as a valve to close the same. The gas inlet, 10,
is then closed by a door, 23, as shown in fig. 4, which, when the inlet is opened, is
either removed or suspended above the inlet, as shown in fig. 3. Air for the combus-
tion of the gas is admitted by an annular opening formed around the gas pipe, 18, by
making such pipe of smaller diameter than that of the gas inlet, 10, as shown in figs. 1,
2 and 3. The gas outlet, 11, is controlled by a sliding door or valve, 24, which moves
laterally across the top of the outlet in guides or ways, 25, being operated by a
shaft 26, by means of a pinion, 27, mounted on the shaft engaging with a rack, 28,
attached to the slide, 24, (see figs. 2, 3, and 4). The shaft, 26, extends along the top
side of the stoves, and by means of the construction named operates all of the top
valves of the group of stoves. It is provided at one end, or any other convenient
place, with a pulley, 29, for which a suitable chain or belt, 30, extends to the pulley, 31,
mounted on a shaft and operated by a windlass, 32, at the surface of the ground, or by
other suitable power appliance. When it is desired to take the stove off gas, the
connection pipes, 18, are withdrawn, the gas inlets, 10, closed and then the sliding
valves, 24, at the tops of the stoves are closed. If it is desirable to protect the bed-
plate and guides, 25, of the valve, 24, from the heat of the escaping gases, it can be
done by the use of a short pipe or tube, 34, (figs. 1, 3 and 4), which is pivotally con-
nected to the outer end of the guide plate, 25, by rods, 35, one on each side, which in
turn are pivotally connected to the pipe at a suitable point above the guide plate ; and

page_text: by pivotally connecting the pipe by means of longer rods, 36, one on each side, to the
valve, 24, the said rods 36, being also pivotally connected to the valve. When thus
connected, the pipe, 34, occupies a vertical position over the gas outlet, 11, when the
valve, 24, is open, the lower end of the pipe extending down inside of the guide
plate, 25, and resting upon the top of the stove; but when the valve, 24, is closed, the
rods, 36, push it up out of its seat and cause it to turn on the rods, 35, so that it is not
only raised out of its seat, but moved backwards and deposited on the top of the stove
out of the way of the valve, thereby permitting the latter to come to its seat over the
gas outlet, 11, as illustrated in fig. 4. The pipe, 34, thus acts as a chimney to the
stove. I do not, however limit myself to the slide valve, 24, as it is evident that I can
close the gas outlet, 11, by other well known means, such, for instance, as the ordinary
damper. This is a detail of construction which may be modified in various ways by
the skilled furnace builder.
These stoves have each a direct passage for the gas from the gas inlet to the gas
outlet, while the air traverses the entire series, entering at or near one end of one stove
and passing thence to the next stove at or near the other end, and so on, traversing
every stove of the series, whether there be two, three, or more, before it passes out at
the exit.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I 'declare that what I
claim is.
First. The combination of a series of hot blast stoves, connected by alternate high
and low openings, forming a continuous air passage therethrough; with separate gas
inlets at the base, and separate gas outlets at the top of cach stove; substantially as
and for the purposes described.
Second. The combination in a hot blast stove, of a gas outlet at the top with a
sliding valve for closing the same, and a pipe pivotally connected by rods to a stationary
point on the opposite side from the valve, so that when the valve is opened the pipe
shall occupy a vertical position over the gas outlet, the pipe shall be raised out of the
path of the valve, substantially as and for the purposes described.
Third. The combination with a row or series of hot blast stoves, each having a gas
outlet at the top, controlled by a sliding valve, provided with a rack; of a power shaft
extending transversely to the valves and provided with pinions engaging the racks ;
a pulley on said shaft; and a chain or belt extending to the ground for actuating the
shaft; substantially as and for the purposes described.
Fourth. A series of hot blast stoves having air ports opening from one to the other,
each stove of the series being provided with a gas inlet and outlet port, so that the gas
shall pass through each stove independently of the other, and the air shall pass from
one stove to the other; substantially as and for the purpose specified.
Dated this 4th day of March 1889.
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