IMPROVEMENTS IN REGENERATIVE HOT BLAST STOVES FOR BLAST FURNACES
Year: 1882

page_text: LETTERS PATENT to Benjamin Ford, Engineer, Middlesbrough on Tees, and
John Moncur of the Distington Iron Works Cumberland for an Invention
of IMPROVEMENTS IN REGENERATIVE HOT BLAST STOVES FOR BLAST
FURNACES
PROVISIONAL SPECIFICATION left by the said Benjamin Ford and John
Moncur at the Office of the Commissioners of Patents on the 15th August
1882.
BENJAMIN FORD, Engineer Middlesbrough on Tees and JOHN MONCUR of
the Distington Iron Works Cumberland "IMPROVEMENTS IN REGENERATIVE
HOT BLAST STOVES FOR BLAST FURNACES."
Our improvements have reference to that class of stoves for heating the blast
for Blast Furnaces called regenerative or fire brick stoves. In using these stoves
two or more similar stoves are employed, which are alternately heated by burning
gas supplied from the blast furnace or other source of heat and the blast to be
heated is alternately directed into, and is caused to pass through these stores, and
is in this manner heated. Each stove generally consists of a vertical cylindrical
iron casing lined with fire brick, or other refractory material the interior con-
taining an arrangement of the same material, in the form of parallel walls, with
transverse stays having spaces or passages between (or other open brickwork)
so that this material can be heated by the burning gas pervading these spaces or
passages and afterwards by shutting and opening suitable valves, the blast to be
heated is passed through the same spaces or passages and thence to the blast
furnace.
It is obvious that by this arrangement the highest temperature of the blast thus
heated, will be when it first passes over the heated surfaces, and in all regenerative
stoves hitherto erected the temperature continues to fall, causing great irregularity
and thus seriously interfering with the work and economy of the blast furnace.
Now our first improvement consists in dividing the regenerator and the upper
part of the combustion chamber into two separate divisions by a vertical wall,
carried from foundation to roof. This wall in the combustion chamber is supported

page_text: on an arch immediately above the hot blast opening, both divisions communicating
with the chimney valve, by suitable internal valves, placed in the coldest part of
the stove. By means of these internal valves, the first blow through after the
stove has been heated, can be made to pass through only one half of the regenerator,
the other half being held in reserve-and as the temperature in the first half
gradually declines it can be supplemented by the blast being made to pass through
the other half of the regenerator by this means the temperature of the blast can
be so regulated that it can be made to remain much longer nearly constant, and at
whatever temperature may be required and that during the whole of the time
the stove is on blast. By this arrangement of dividing the stove into two
divisions as described, a much better distribution of the gas and heating currents
over the area of the regenerator is obtained than in any existing arrangement,
thereby enabling stoves of a much larger diameter to be successfully used.
Our second improvement consists in admitting the gas for combustion into the
stove, by means of a passage or flue in the brickwork Lining of the combustion
Chamber, in this passage or flue several openings are made so as to distribute the
gas more equally over the area of the combustion chamber, and thereby also
secure a better distribution of the flame and heating currents over the area of the
regenerative part of the stove.
In working regenerative Hot-blast stoves, it is found that their heating power
is interfered with and becomes inefficient from a nonconducting material carried
into them by the gas, and which is deposited on their heating surfaces during its
combustion while the stove is being heated. This deposit therefor requires to be
removed from time to time.
"
Now our third improvement consists in expelling the deposit by means of the
internal valves referred to in Our first improvement." These valves are alternately
caused to open instantiously one at every change from blast to gas, and by the
force and velocity of the contained air, the deposit is carried with it through the
chimney valve or any other external valve; The heating surfaces of the stove are
in this way kept entirely clean.
In connection with the foregoing improvements in stoves for heating blast, the
Regenerator we adopt may be composed of an arrangement of perforated bricks or
tiles, or we adopt an arrangement of parallel walls with transverse stays of a
triangular section, placed with the apex upwards; in this way presenting no level
surface on which the deposit already referred to may lodge; These stays are so
placed that the stays in the row above, are over the openings between the stays
in the row below and so on alternately throughout the whole regenerator so as
to thoroughly break up the passing currents and assist in absorbing and giving
out the heat.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Benjamin Ford and John Moncur in the Great Seal Patent Office
on the 15th February 1883.
BENJAMIN FORD, Engineer, of Middlesbrough-on-Tees, and JOHN MONCUR, of
the Distington Iron Works, Cumberland "IMPROVEMENTS IN REGENERATIVE HOT
BLAST STOVES FOR BLAST FURNACES
"
Our invention relates to that class of stoves for heating the blast for Blast
Furnaces known as regenerative or fire brick Stoves. In using these stoves, two
or more similar stoves are ordinarily employed, which are alternately heated by
burning gas supplied from the blast furnace or other source of heat, and the
blast to be heated is directed into, and is caused to pass through, these stoves
alternately, and is in this manner heated. Each such stove ordinarily consists of a
vertical cylindrical iron casing lined with fire brick, or other sufficiently refractory
material, the interior containing an arrangement of the same material, in the form
of parallel walls, with transverse stays, having spaces or passages between (or other
open brickwork), so that the material can be heated by the burning gas pervading
these spaces or passages, and afterwards by shutting and opening suitable valves,
the blast to be heated is passed through the same spaces or passages and thence to
the blast furnace.
It is obvious that by this method of arrangement the temperature of the blast
thus heated, will be highest when it first passes over the heated surfaces, and in
all regenerative stoves hitherto erected the temperature continues to fall, causing
great irregularity and thus seriously interfering with the work and economy of the
blast furnace.
Our present invention has for its objects novel methods of construction and
arrangement by which, first, the temperature of the blast can be so regulated that
it can be made to remain much longer nearly constant, and at whatever temperature
may be required, during the whole time that the stove is in operation, than in such
stoves as heretofore ordinarily constructed and used; second, a better distribution
is obtained of the flame and heating currents over the area of the regenerative
part of the stove; and third, the heating surfaces of the stove are kept clean.
The first part of our improvements consists in dividing the regenerator and the
upper part of the combustion chamber into separate divisions by a vertical wall
carried from foundation to roof; this wall in the combustion chamber being
supported on an arch immediately above the hot blast opening, the separate
divisions communicating with a chimney valve, by suitable internal valves, placed
in the coldest part of the stove. By means of these internal valves, the first blow-
through, after the stove has been heated, can be made to pass through only one
part of the regenerator-the other part being held in reserve-and as the
temperature in the first part gradually declines it can be supplemented by the
blast being inade to pass through the other part of the regenerator, and by this
means the temperature of the blast can be so regulated that it can be made to
remain much longer nearly constant, and at whatever temperature may be required,
and that during the whole time the stove is on blast.
By this arrangement of dividing the stove into separate divisions, as described, a
much better distribution of the gas and heating currents over the area of the
regenerator is obtained, than in any existing arrangement, thereby enabling stoves
of a much larger diameter to be successfully used.
The second part of our improvements consists in admitting the gas for
combustion, into the stove, by means of one or more passages or flues in the
brick work lining of the combustion chamber, in these passages or flues several

page_text: openings being made so as to distribute the gas more equally over the area of the
combustion chamber and thereby secure a better distribution of the flame and
heating currents over the area of the regenerative part of the Stove.
In working regenerative Hot blast stoves, it is found that their heating power is
interfered with and becomes inefficient from a nonconducting material carried
into them by the gas, and deposited on their heating surfaces during its combustion,
while the stove is being heated. This deposit therefore requires to be removed
from time to time.
The third part of our improvements consists in a method of expelling the deposit
by means of the internal valves already referred to. These valves are alternately
caused to open instantaneously, one at every change from blast to gas, and by the
force and velocity of the contained air, the deposit is carried with it through the
chimney valve, or any other external valve. The heating surfaces of the stove are
in this way kept entirely clean. In connection with the foregoing improvements
in Stoves for heating blast, the Regenerator we adopt may be composed of an
arrangement of perforated Brick or Tiles.
We prefer to adopt a novel arrangement of parallel walls with transverse stays
of a triangular section placed with the apex upwards, in this way presenting Do
level surface on which the deposit already referred to may lodge. These stays are
so placed that the stays in any row are above the openings between the stays in
the row below, and so on alternately throughout the whole regenerator, so as to
thoroughly break up the passing currents, and assist in absorbing and giving out
the heat.
The accompanying drawings are in illustration of our invention. Figures 1
and 2 are vertical sections, taken at right angles, through a regenerative hot blast
stove, and figures 3 and 4 are horizontal sections at different heights through the
same stove.
Figures 1 and 2ª are vertical sections through a similar regenerative hot blast
stove of somewhat modified method of construction, and figures 3 and 4ª are
horizontal sections through the same stove at different heights. Figure 5 shews on
a larger scale, a modified form of the improved stays which we use between the
parallel walls of the regenerative part of the stove. The same letters of reference
indicate the same parts in the several figures. a is the valve through which the
gas by which the stove is heated enters from the blast furnace or other source of
supply into horizontal flues b, b, from which several apertures b', b, b' open into
the lower part of the combustion chamber c. Air is admitted by a valve at d
through a passage into horizontal air flues f which have openings ff, into the
combustion chamber c immediately above the gas apertures 6. The upper part of
the combustion chamber c is provided with staying walls g, g. The regenerator
itself is composed of parallel walls supported by triangular or more or less
lozenge-shaped stays and supported by girders 7. Internal valves i, i, which can
be readily operated from outside the stove (as shewn in figure 2) open into the
central Hue, which communicates with a chimney by a valve l. The cold blast
to be heated is admitted through a valve at n, and the heated blast passes to the
furnace through a valve at p.
In figures 1, 2, 3, and 4, the regenerator is shewn divided into two compartments
by the central wall m, and as the combustion chamber c also divides the regenerator,
the latter is thus divided vertically into four compartments. The lower part of each
of these compartments can be made to communicate, as desired, with the flue by
apertures provided with the valves i where the temperature is lowest, and by
these means each of the compartments or divisions of the regenerator can be put in
communication with the flue and chimney, or can be shut off as desired.
In order to heat the stove, gas is admitted through the valve a to the flues b
and through the apertures 6 into the combustion chamber c, air also entering
through d into the flues fand through the openings f¹ to mix with the gas, the
mixture being thus properly distributed over the combustion chamber c where it
burns. The interior of the chamber and the staying walls y become intensely

page_text: heated, and the heated currents and products of combustion pass down and through
the regenerator k, the parallel walls of which and stays h' present a large extent of
surface by which the greater part of the heat is absorbed.
The products of combustion then pass through the valves i, to the flue k and
through the valve to the chimney.
In order to heat, and equalize the temperature of the blast in the stove heated
in the manner just described, the gas valve a, the air valve at d, and chimney
valve are closed, and cold blast is admitted through a valve at n, and passing
through the flue , enters the lower part of the regenerator through the valves i,
which can be opened or closed from outside as already described. In its passage
slowly up the regenerator the blast is thoroughly diffused by coming in contact
with the triangular or lozenge shaped stays h³, and the parallel walls h and absorbs
the beat from their highly heated surfaces.
It then passes down the intensely heated walls of the combustion chamber c and
through a hot blast valve at 2 to the blast furnace.
The blast in its passage having acquired the maximum temperature of the stove,
this temperature will gradually decline, great irregularity in the working of the
blast furnace being thus caused, and in order that this irregularity may be remedied
and regulated without requiring the use of three or more stoves to a furnace, we
adopt the following novel method of operation, by which the blast can be made
to pass through the valves i to one, two, three, or all of the four compartments of
the regenerator as may be desired.
Supposing that the stove has been heated to a maximum temperature, and that
it is required to have a nearly equal temperature of the blast, though somewhat
lower than the maximum heat of the stove, such temperature to continue equal for
a considerably longer time than if the blast was passed through the whole of the
stove at once, as in the ordinary manner, the desired equality of temperature can
be obtained and regulated in different ways by the valves i. For instance, the
blast may be blown through one or more of the compartments of the regenerator,
the others being shut off by the valves i, and the cold blast being thus prevented
from passing through them. These shut-off compartments would retain their heat,
and as the temperature of those through which the blast is passing begins to fall
then by gradually opening the other valves the blast would be reinforced and
supplemented by that made to pass through the hot compartments of the
regenerator, and its temperature would continue for a considerable time nearly
equal.
Or, sometimes we blow the cold blast through-say-two quarters or divisions of
the regenerator, and as soon as the temperature of the blast begins to fall, we open
another quarter or division and gradually close one of the divisions first opened,
thereby allowing more time for the blast to absorb the heat in its passage through
this division.
Then to still further supplement the heat we open the fourth or last quarter or
division, and gradually close the first blown through.
By means, therefore, of the internal valves i we maintain a practically equal
temperature of blast from each stove during the whole time it is on blast.
In order to keep the heating surfaces of the stove clean, it is necessary to remove
a substance highly non-conducting of heat which is deposited upon them during
the combustion of the gas. When this deposit is newly formed it is easily removed
being of a light powdery nature, but after it has been allowed to accumulate and
has been subjected to the pressure of the blast in the stove it adheres firmly and can
only be removed by scrapers or brushes.
Attempts have heretofore been made to utilize the force of the contained air in
the stove to expel this deposit but by our novel method of constructing the
regenerator and part of the combustion chamber in two or more separate compart-
ments each communicating when desired by means of the internal valves i with aạ
valve leading to a chimney, or other external valve, we are enabled to cause the

page_text: force of the contained air in the whole stove at blast pressure to rush through the
comparatively limited area of only one quarter or division of the stove, and in this
way such contained air is made to rush through each division in turn, one at each
change from blast to gas.
In this way the dust or deposit is carried through the chimney valve into the
chimney flue, or through any other suitable external valve to a proper receptacle,
and in this way the heating surfaces of the stove are kept clean.
And in order further to lessen the settlement of the dust or deposit referred to
upon the stays between the parallel walls of the regenerator, we make these stays
of such shape that they present no flat horizontal surface upon which the deposit
may lodge, but we make them triangular or more or less lozenge-shaped in cross
section as shewn in figures 2, 4, 2ª and 4ª the walls being properly made to support
them, as shewn in figure 5.
We prefer to construct and arrange the internal valves i so that they can be
instantaneously opened when required, or sometimes we place a separate external
cleaning valve o in the neck of the flue so arranged that it can be instantaneously
opened, and by opening any of the internal valves i we discharge the contained air,
carrying with it the deposit which it is desired to remove, through the quarter or
division of the stove with which the open internal valve is in connection, and
either through the valve to the chimney flue, or through any external valve into
a suitable receptacle.
Or, instead of the separate cleaning valve o we sometimes use an external valve
(capable of being rapidly opened), to each compartment of the regenerator, and in
order to clean any compartment, we open its internal valve and the external
valve connected with it, the other internal valves & having been previously closed.
By this means the contained air is compelled to pass down the particular compart-
ment to which the opened external valve is connected. The external valves
described may be arranged to discharge into a flue connected with the chimney flue
or into other suitable receptacle.
In figures 1ª, 2a, 3a, and 4ª, the method of operation of the stove is similar to
that already described, but its construction is somewhat modified, the combustion
chamber being shewn circular in plan, and the regenerator being divided into four
compartments by four dividing walls.
We do not confine ourselves to the precise form and arrangement of the several
parts of the apparatus as herein before described and shewn, which may be modified
to suit varying circumstances, nor do we claim generally the use of external valves
for the purpose of cleaning Regenerative hot blast stoves, but what we desire to
claim is:
First, The method of dividing the regenerator of the stove into compartments,
each of such compartments being connected by means of internal valves with a flue
through which is admitted the cold blast which is to be heated so as to regulate and
produce a uniform temperature of blast during the whole time that the stove is
blowing, substantially as described and shewn in the drawings.
Second, The method of connecting each of the compartments into which the
stove is divided as described by means of internal valves with a flue leading to a
chimney or other receptacle, so that the whole of the contained blast can be
discharged when desired through either one of the compartments for the purpose of
carrying away the deposit from combustion, substantially as described and shewn
in the drawings.
Third, The combination with the internal valves arranged and operated as
described, of external valves in connection with each compartment, substantially as
and for the purpose described.
Fourth, The method of forming the stays between the walls of the regenerator,
triangular or more or less lozenge-shaped and without flat horizontal surfaces,
substantially as and for the purpose described and shewn in the drawings.
Fifth, the method of construction of the combustion chamber, so that it divides

page_text: the regenerator into two compartments, and so that the heated currents are equally
distributed over the Regenerator, Substantially as and for the purpose described and
shewn in figures 1, 2, 3, and 4 of the accompanying drawings.
In witness whereof, we the said Benjamin Ford and John Moncur have
hereunto set our hands and seals this twelfth day of February in the year
of our Lord 1883.
BENJAMIN FORD (L.S.)
JOHN MONCUR.
(LS.)