Metallurgical Purposes.
Year: 1887

page_text: Date of Application, 21st July, 1887
Complete Left, 19th May, 1888
Complete Accepted, 22nd June, 1888
Metallurgical Purposes.
We H. C. BULL & COMPANY Limited and HENRY CLAY BULL, Engineer, both of
31 Poultry London do hereby declare the nature of the said invention to be as
follows:-
:-
This Invention relates more particularly to stoves for heating air for metallurgical
processes and known as "hot air stoves."
The object of this Invention is to work and construct stoves of this type in such a
manner that air of a very high temperature may be produced and with an efficient
and simple apparatus.
An air heating stove working and constructed with our improvements applied
thereto consists as follows. Where continuity of supply of hot air is required, a
quantity of stoves is required some of which will be being heated while the other, or
others is, or are heating the air which is being passed through it, or them.
The stoves are heated by gas and air the gas being derived from any suitable source
as for instance in the case of their being used for supplying a blast furnace with
hot air, the gas used would be the waste gases from such blast furnace.
The stoves consist preferably of cylinders lined with fire-brick, or other suitable
and equivalent material and provided with a combustion chamber at the top and an
interior cylinder of brickwork surrounded by diverging, or radiating walls.
Suitable valves are provided for the carrying out of the working of the stoves.
One valve is for the admission of waste gas from the blast furnace, or other source of
gas supply and one is for the outlet of the heated air-which also serves for the inlet
of hot air to burn the gases. The third valve serves to make, or break communi-
cation between the bottom of the stoves and a chimney flue, whilst the fourth valve
serves to admit cold air from the blowing engine.
For a continuous supply and to obtain air of a higher temperature it is preferred
to use a battery of stoves say four for example. In such a case a part of the hot air
from one stove is used to support combustion of the gas used in heating another
thereby obtaining a greater heat in the stove than is possible under the ordinary
practice.

page_text: In operation the gas is admitted to the bottom of the central chamber of a stove
(a battery being employed) and a portion of the hot air from one of the other
stoves is also supplied to support combustion of the gas. The flame and products
of combustion pass from the central passage above specified into the combustion
chamber and down through the passages formed by the radiating, or diverging
brickwork and out at the bottom of the stove. The cold air is admitted at the bottom
and rises through the outer passages and then passes down the central chamber, or
cylinder and is led out to a hot air main, or culvert.
If desired the outer spaces of the stove may be filled with refractory material in
the form of spheres.
When a stove is heated sufficiently, the gas is shut off from the stove and turned
on to the next in the battery. The hot air is allowed to flow for a short time after
the waste gas valve is closed in order to carry out through the chimney the products
of combustion and fill all parts of the stove with hot air previously to the admission
of the cold air.
Dated this 20th day of July 1887

page_text: H. C. BULL AND COMPANY Limited and HENRY CLAY BULL Engineer, both of
31 Poultry, London, do hereby declare the nature of the said invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
This Invention relates more particularly to stoves for heating air for metallurgical
processes and known as
hot air stoves."
The object of this Invention is to work and construct stoves of this type in such a
manner that air of a very high degree of temperature may be produced and with
an efficient and simple apparatus.
An air heating stove constructed and working with our improvements applied
thereto consists as follows.
It must be first stated that where continuity of supply of hot air is required, a cer-
tain number of stoves is required, some of which are being heated while the other, or
others is, or are heating the air which is being passed through it, or them.
The stoves are heated by gas and air the gas being derived from any suitable source
as for instance, in the case of their being used for supplying a blast furnace, the gas
used would be the waste gases from such blast furnace and the air used would be
previously heated.
The stoves consist preferably of cylinders lined with fire brick or other suitable or
equivalent material, and provided with a combustion chamber at the top and an
interior cylindrical passage of brickwork surrounded by diverging, or radiating
walls.
Suitable valves are provided for the carrying out of the working of the stoves, one
valve is for the admission of waste gas from the blast furnace, or other source of gas
supply, and one is for the outlet of the heated air-which also serves for the inlet of
hot air to burn the gases used for heating up the stove.
The third valve serves to
make, or break communication between the bottom of the stoves and a chimney flue,
whilst the fourth valve serves to admit cold air from the blowing engine.
For a continuous supply, and to obtain air of a high degree of temperature it is
preferred to use a battery of stoves; say four for example. In such a case a part of
the hot air from one stove is used to support combustion of the gas used in heating
another thereby obtaining a greater heat in the stove than is possible under the
ordinary practice.
If desired the outer spaces of the stove may be filled with refractory material in
the form of spheres.
When a stove is heated sufficiently, the gas is shut off from the stove and turned
onto the next in the battery. The hot air is allowed to flow for a short time, after
the waste gas valve is closed, in order to carry out through the chimney the products
of combustion, and fill all parts of the stove with hot air, previously to the admission
of the cold air.
That this Invention may be clearly understood, there is annexed to this Specification
a sheet of Drawings, illustrative of an example of hot air stove with our improve-
ments applied thereto. The Drawings (which form a part of this Specification) are

page_text: marked with letters and figures of reference corresponding with those used in the
following explanation of them. Like letters are used to denote like parts in the views
of the Drawings. The description herein contained together with the Drawings will
be sufficient to enable others skilled in the art to which this Invention belongs to
make and put the same into practice.
In the Drawings
Figure 1 is a sectional elevation through the stove, and Figure 2 is a plan in section
of same through a Figure 1.
It will be seen in the Drawings that a portion of a second stove, and certain pipes
and valves of other stoves are shown. These are given to point out a convenient
disposition of stoves and their accessary valves, pipes and other parts, where con-
tinuity of supply of hot air may render a battery of stoves necessary.
The example of stove illustrated is of a cylindrical form, and of brickwork, having
outside iron binding bands of the ordinary type a is an outside casing of common
brickwork and a¹ is an internal annular lining of fire brick. The case a and the
lining a¹ are continued over the top of the stove to form a dome A, within which is
the combustion chamber B. Concentrically with the outer casing lies the inner brick-
work cylindrical passage C. This passage is continued horizontally at the bottom
and is here designated C. At the end of this passage is the valve D, through which
heated air is admitted to, or allowed to pass from the stove into the hot air culvert, or
main E. The culvert E is common to all the heated air valves D of the stoves, so
that hot air can be supplied to it, or taken from it, accordingly as the operation of the
respective stoves of a battery may render it necessary. For example when a stove is
being heated, and hot air is being used to support combustion of the gas used that
hot air would be supplied from the culvert E through the seat of the valve D of that
stove the hot air so used having been made by another stove of the battery. On
the other hand when a stove is being used and operated for the production of hot
air, that hot air would be delivered into the culvert E, through the seat of the
valve D.
The valves controlling the egress of the gases, used in heating up the stove are
designated F, and communicate with a common culvert of ordinary type, by which
the gases are taken away to a chimney, or other outlet. The valves F are of similar
construction to that of the valves D. The casings of these valves are also used for
the passage of the cold air, to be heated, to the Stove. H is a pipe through which
the cold air is forced and G are valves, for controlling the supply of air from the
pipe H to the different stoves. The branches of the valves G are connected, as will
be understood, to branches from the main H and the casings of the valves F. Thus
the cold air in travelling to the stoves, is led from the main H, past the valves G, and
through the space above the valves F, in their casings.
The inlet for the gas used to heat the stoves is controlled by the valves I,
and is conducted to them by branches from a main . To bring it into the
lower portion of the passage C. a duct J is built in the stove to convey it hence.
All the valves and valve rods and valve seats are maintained at a safe working
temperature by water lining them in any of the well known suitable ways, ordinary
flat valves as shown by valve D, are preferred for the purpose. The operation of the
valves is carried on upon a platform K, at the upper part of the stoves, and suitable
known types of mechanisms are employed to raise and lower them from and onto
their seats. For instance a lever device m is employed to work the valves D, such
device being connected to the valve rod m¹ by a chain m². The rod m' is provided
with a handle at its upper end for turning the valve upon its seat when required. The
valves F and I are operated by an ordinary screw lifting device m. But none of
these particular construction of mechanisms, or valves are essential to the effective
operation of the Invention.
L are passages communicating between the combustion chamber B and the vaulted
or arched space, or chamber M at the bottom of the stove. This vaulted space M
occupies the whole of the lower portion of the stove, except_that_taken up by the
passage C, and constitutes a common chamber to the passages L, and a space in which

page_text: cold air entering the stove is distributed. The passages L are formed by the radiating
fire brick walls, which are built in between the walls a and wall of the passage C:
a strengthening wall l, concentric with the walls Cand a, being introduced. The
walls and are shown in section in Figure 1, but the passages L are indicated
through them by dotted lines. An aperture O is formed in the dome A of the stove,
by which access can be had to the interior of the stove. It also serves as a relief
outlet, in case of explosion of gas within the stove. For this purpose a weighted
valve P is used to close the aperture, and is placed upon a seat p, at the mouth of the
aperture O.
The operation of heating the stove and subsequently heating air, by the heat
stored in the brickwork of the stove, are as follows: It must be assumed that hot air
from the culvert E and gas from the main are available. Then in order to heat up
the stove, the valves I and D are opened, and the gas and air, under pressure, issue
from the pipe and culvert E respectively, the gas passing the valve I flows down
the passage J, and arrives in the central cylindrical passage C, and the hot air passing
the valve D flows through the passage C¹ also arrives in the passage C. The heat of
the brickwork (assuming the stove to have been already in operation) of the passage C
will be sufficient to ignite the gas thus brought into the presence of the hot
air and a continuous combustion takes place, the heat resulting from the combustion
due to the heated air being very intense. The gas now burning flows up the passage C
and into the chamber B where it distributes itself, returns downwards through the
passages L, and finally arrives in the vaulted space M. From thence it passes into
the valve chest of the valve F (which has been opened) and flows away to the outlet
main. The brickwork of the stove having been heated in this wise, for a certain
period (say 30 minutes) the gas valve I and the outlet valve F are closed. The cold
air is now admitted to the stove, by opening the valve G, (the hot air valve being
already open) and it passes through the case of the valve F into the space M. It
then rises up, and over, the hot walls and of the passages L, and flows into the
combustion chamber B, reverses its direction there and then returns downwards
through the passages C and C', to the supply culvert E. By the above described
alternating processes of heating up and heating the air, the cold air comes in contact
with the cooler portions of the brickwork of the apparatus first, and in contact with
the hottest portion last, namely, the walls of the passage C, where the heat of combus-
tion is the most intense.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:
1. In air heating stoves, heated by gas and of the type herein described, a central
passage, such as C, a chamber, such as B, passages, such as L, and a chamber, such
as M, in which the combustion of the gas is effected in the said passage C, and
the cold air is admitted into the chamber M, operating and constructed, as, or
substantially as set forth.
2. The air heating stove set forth with reference to the Drawings, the parts of
which, namely the passage C, chamber B, passages L, chamber M, and valves F, G,
I, and D, are arranged particularly as described and shown, and operate as, and for,
the purposes specified.
H. C. BULL & Co., LTD.
HENRY CLAY BULL.
By Cheesbrough & Royston,
15, Water Street, Liverpool,
Patent Agents.