Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
37
-- 1 --
~nstallation and process for the Eroduction of hot air
The present invention relates to an installation
for the production of hot air, of the cowper type, com-
prising an enclosure, mainly occupied by a checkerwork ofrefractory bric]cs, a-t least one cold air admission orifice
at the base of the enclosure, at least one hot air outlet
orifice situated at the top of the enclosure, ~nd one or
more burners arranged in the upper part or the purpose of
burning the uels and generating the heat required for
the heating of the checkerwork, as well as a process to be
employed with this apparatus.
Most of the known installations for the production
of hot air are mainly made up of two parts. ~ first part,
known as the combustion shaft, has a burner at the bottom,
into which a combustible gas is injected, particularly
blast furnace gas, in most cases enriched with cok:ing gas,
natural gas, etc. The heat given off by the combustion of
this gas rises -through the combustion shaft, is deflected
by a cupola and redescends into the second part of the
cowper, known as the ckeckerwork shaft, which stores the
heat in its checkerwork of refrac-tory bricks. The hot air
is produced by causing -the air to circulate through the
checkerwork shaft in the opposite direction to the cir_ula--
tion of the combustion gases, i.e. from the bottom upwards.In its passage through the ckeckerwork the air thus recu-
perates the heat which was stored up in this checkerwork
during the combustion of the gases.
Among these known installations a distinction must
be drawn between the "separate shaft" type, in which the
combustion shaft is completely separated from the checker-
work shaft, and the "incorporated shaft" type, in which
the combustion shaft and the checkerwork shaft, although
not identical are situated next to each other in one
single container.
In these known installations the part on which the
~ratest dem~nds are made an~ which is thus most subject to
deterioration is the cupola. The fact is that it is directl~
exposed to the heat and -the combustion flames, since its
r
- 2 - ~ 37
function is to deflect the combustion gases towards the
checkerwork shaf-t. The hottest part of a cowper of this
kind is thus invariably -the cupola, which is also that most
exposed to stresses and therefore the most liable to suffer
damage. This high temperature in the cupola reduces its
mechanical strength and increases the concentration of NOX
ions, which form at high temperatures and which render the
cupola particularly liable to develop what is known as
"intercrystalline stress corrosion", major drawback of
modern cowpers operating at high temperatures and pressures.
The cowpers with incorporated shafts also suffer
from the drawback that the refractory separating wall bet-
ween the combustion shaft and the checkerwork shaft is
likewise exposed to an intensified risk of deterioration.
This is due to short circuits occuring between the combustion
shaft and the checkerwork and manifest themselves in des-
truction of the refractory material owing to the heat surges
- produced by the considerable temperature differences bet-
ween the two sides of the separating wall.
This last problem, inherent in the cowper of the in-
corpora-ted shaft type, has been solved thanks to another
type of installation known as the "Cowper without combustion
shaft", in which the combustion is effected above the re-
fractory checkerwork, either in the space underneath the
~5 cupola or in a separate combustion chamber above the cupola.
.
An example of an installation of this kind is described in
German Patent application 2,123,552. The elimination of
the combustion shaft offers the additional advantage of
increasing the space available for the checkerwork or
reducing the diameter required. A further advantage of this
design is its symmetrical construction.
The cowpers without combus-tion shaft, however, have
no-t provided any solution to the problem arising in the
heating of the cupola, the wall of this latter still being
the zone subjected to the most intensive heating, since
either the combustion occurs immediately below it or the
combustion gases are conveyed straight to the said wall.
This type of cowper therefore~invariably lnvolves the pro- ;
bl`ems of intercrystalline corrosion.
637
-- 3 --
I~he purpose of the present invention is therefore
to provide a new type of cowper without a com~ustion shaft
and free of the drawbacks inherent in the cowpers already
known.
For this purpose the invention provides an install-
a-tion which is characterized by the fact that each burner
is integrated into a refractory ~all provided with cavities
corresponding -to each burner and forming with the front
portion of the latter a "combustion dish" from which a
conical flow of heat is emitted, each of these burners bein~
orientated to ensure that these heat flows act direct on the
; entire upper surface of the checkerwork without any con-
tact between this surface and the flames.
In this type of burner the combustion takes place
in a front "dishl' of the burner, and the combustion gases,
as well as the heat given off, are conveyed direct to the
upper surface of the refractory checlcerwork. The resulting
advantage is that the heat is transmitted to the place where
it is required and without first being reflected from the
cupola. This latter therefore no longer has to function as
; a deflecting device for the combustion gases and the heat,
its sole function now being that of an arch or cover serving
to close the upper part of the installation. Thanks to this
construction , the temperature of this arch can be reduced
by 100-150 for comparable operating conditions.
Whereas in conventional cowpers the hottest point r
and that subject to the greatest stress and having the least
strength, was the cupola, the hottest point in the cowper
according to the present invention is that subject to the
minimum stress, in addition to being that of which the heat
is recuperable, i.e. the upper part of the refractory
checkerwork.
;- A further advantage offered by the adoption of
flameless burners and the elimination of the combustion
shaft is the reduction of the proportion of NOX ions for a
given hot air temperature.
n the simplest version one single burner is posi-
tioned in the centre of the arch of the cowper, the hot
air outlet orifice being situated by the side of this burner.
i37
In another version the hot air outlet orifice is
in the centre of the arch, the burners being distributed
around the orifice. In this case there may be either
three or four such burners, occupying the points of a
triangle or square respectively.
In a further multi-burner version the burners and
the hot air outlet orif$ce are arranged around the centre
of the arch.
As this arch will now be subject to less stress,
particularly owing to the lower temperature and the reduc-
tion of the intercrystalline corrosion, a number of openings
can be provided in the arch, in order to position the hot
air outlet orifice and the burners without appreciably
detracting from the static strenght of the assembly. The
arch may be a simple brickwork structure or else a "sus-
pended arch", l.e. consist of refractory bricks suspended
by securing hooks from the outer metal cladding.
In another version the burner or burners are simply
affixed vertically to a circular slab mounted transversely
~0 above the checkerwork and forming together with an upper
casing a hermetic chamber into which the supply plpes for
the burners penetrate. In this version the hot air outlet
orifice may be situated between the slab and the checker-
work or extend out vertically from the centre.
; 25 The invention likewise covers a process for the
production of hot air in an installation of this last type,
this process comprising a combustion period and an air
period, and being characterized by the fact ~hat duriny
the said two periods the slab and also the chamber above
it are cooled. This cooling can with advantage be effected
by introducing combustion air into the chamber during the
combustion phase and cold air during the air phase. The
cold air thus circulating in this chamber can be recycled
and reintroduced at the bottom of the checkerwork in such
a way as to enable its heating to be utilized in the
chamber above the slab. In addition to the cooling effect,
the circulation of the cold air in this chamber ensures
that the pressure on the respective sides of the slab will
be balanced out.
L637
-- 5 --
In a further embodiment of the invention a cooling system
is provided in the slab, in which system a supply of water
or else air which can be re-used, in the process adopted,
is caused to circulate.
Further features and characteristics will become
apparent to those skilled in the art from the following
detailed description of certain possible embodi~ents
oE the invention, by reference to the accompanying drawings
wherein like reference numerals refer to like elements, and
in which the respective figures are as follows :
Figure 1 : a schematic cross section of a first
; embodiment of a cowper in accordance with the present
invention.
Figure la : a schematic partial plan view of the
version shown in E'igure 1.
Figures 2, 2a : analogous view to the preceding
figures, showing a second versi.on.
Figures 3, 3a : V:Lews corresponding to those pro~
vided by Figures 1 and la, illustrating a third embodiment.
Figures 4, 4a corresponding -to figures 1 and la
respectively of the version having one single burner but
provided with the suspended type of arch.
Figure 5 : a schematic vertical section through
the upper part of another type of cowper according to the
invention.
Figure 5a : a partial plan view of the version shown
in Figure 5.
Figures 6, 6a : a variant of the version shown in
Figure 5, with a schematic diagram illustrating the process
adopted.
Figures 7, 7a : a schematic diagram of the process
description with re~erence to Figure 6, but this applied
to the version shown in Figure 5.
Figure 8 : A schematic diagram of a version similar
to that shown in Figure 6, but with an air-cooled slab.
Figure 8a : a schematic horizontal sec-tion in the
plane 8a-8a through the slab shown in Figure 8.
Figure 9, 9a : a variant of the process described~
by reference to Figure 6.
.
\
1161G37
-- 6
Figure 10 : a schematic diagram of a variant of
the embodiment shown in Figure 8, but with a water-cooled
slab.
Figure lOa : a schematic horizontal section in the
plane lOa-lOa through the slab shown in Figure 10.
Figures 11, lla : an analogou.s embodiment to that
shown in Figure 2.
Figures 12, 12a : the adaptat:ion of the sus~pension
system of Figure 11 to the versions provided with a slab.
Figures 1 and la illustrate the upper part of a
first embodiment of a cowper 10. This cowper comprises one
single shaft 12 formed by a checkerwork of refractory bricks
which are alternately heated and traversed by air from the
bottom upwards in order to recuperate the heat stored up
in the refractory bric]cwork. The shaft 12 is closed at the
top by an arch or dome 14 consisting of an assembly of
refractory bricks 16 surrounded by an external metal clad-
ding 18. This arch 14 is provided with an o~ltlet 20 for
the hot air rising through the refractory checkerwork of the
shaft 12.
The version of the present invention shown in Figure
1 comprises a burner 22 which may be of the type described
~- ~ in French Patent 1,205,382. This is a burner essentially
consisting of an enclosure 24 provided with an inlet 26
; : :
~25 for the combustible gases and an inlet 28 for the combus-
tion air, the combustion itself taking place in a "bowl" 30
also containing the tip of a pilot flame, not shown in
the drawing.
The characteristic function of this burner is to
prcduce a very high degree of heat radiation, thanks to
a whirling flame inside the bowl 30. The burner will be
simply affixed to a flange 32 of the cladding 18 of the
arch 14, while an aperture 34, preferably diverging slight-
ly, with an opening angle corresponding to the angle of
the "cone" emitted by the burner 22, will be provided in
the refractory brickwork 16. This emission cone is shown
schematically by dotted lines and is marked 36.
During the phase in which the refractory brickwork
ls heated up the combu~t1on gases anù co bust1on alr are
~6~7
-- 7 --
introduced into the burner 22 at a pressure slightly
above the atmospheric, in order to cause the combustion
gases to be very rapidly mixed and to form a continuous
flow all the way down to -the bottom of the checkerwork
shaft 12. The emission of the combustion gases and that
of the thermal radiation take place at a divergent angle
represented b~ -the cone 36, the maximu}~ heating occurring
on the upper sur~ace of the refractory checkerwork, i.e.
where the heat is really required and where it can be re-
cuperated.
On the other hand, the arch 14, contrary to thearches and cupolas of all the installations known up to
the present is less exposed to thermal radiations and re-
mains "in the shade" from the heat given off by the
burner 22.
To obtain a regulated temperature o~ 1250C for
the hot air, as is the case in modern blast furnaces, the
temperature of the refractory checlcerwork must be increased
to 1400C, at all events in its upper part. If this
temperature is -to be obtained the temperature at the
outlet of the buxner must reach 1500C. Now i~ such tem-
peraturesare adopted in conventional installations the
temperature of a cupola, which reflects the combustion
gases and the heat of the combustion shaft towards the
checkerwork will be over the 1400C to which the temperature
of the xefractory bricks has to be brought, i.e. the tem-
perature of the cupola may rise to as much as 1450C and
over. At such a temperature, needless to say, its strength
is seriously reduced, in addition to which it i5 exposed
to the intercrystalline corrosion phenomenon.
On the other hand, for comparable operating con-
ditions, i.e~ the heatin~ of the upper part of the checker-
work to 1400C and a combustion temperature of 1500C, the
temperature prevailing in the arch 14 is only about 1300C,
which is about 150C lower than the temperature occuring
in the cupolas of conventional installations. Now it is
a well known fact that a reduction of 100 or even 150C
ln the temperature is quite considerable for these thermal
conditlons, particularly as re~ards the increase o~ the
~L~6~63~
- 8 -
statlc s-trength of the arch and the reduction of the rlsk of
intercrystalline corrosion.
Furthermore, in view of the short distance between the
burner and the refractory checkerwork, and in view of the fact
that the burner used is operated more efficiently than the
burners employed in the conventional cowpers, it is even
possible to adopt less than 1500C at the outlet of the burner
in order to heat the bricks to 1400C, or else, while still
operating at 1500C, to raise the temperature of the upper part
~ 10 of the checkerwork to above 1400C.
: The proximity of the burner 22 of the refractory checker-
work also enables the temperature of the said checkerwork to be
regulated more satisfactorily, resulting in better control over
the temperature of the hot air at ~he outlet of the cowper.
A further important advantage is the reduction in
~ the formation of NOX ions. The fact is tha-t experience
: has shown that they :Eorm to a very considerable extent at
high temperatures particularly at those exceeding 1400 C,
so that, as already mentioned r it is in the cupola of
conventional cowpers that the greatest concentration of
NOX ions is to be found. Now if the temperature of a cupola
can be reduced to below 1400C one of the causes or condi-
tions which favour -the formation of NO~ ions is eliminated
i.e. the concentration of NOX ions is greatly reduced, the
~ 25 risk of the intercrystalline corrosion phenomenon being
; ~ rendered far smaller at the same time.
It goes without saying that the elimination of
the heating of the parts which do not require to be heated,
such as teh walls of the combustion shaft and, above all,
the cupola, greatly reduces the fuel required for the
heating of the refractory checkerwork, or else enables it
to be heated more satisfactorily with the same quantity of
fuel. In either case there is naturally an energy gain.
Whereas in the case of the cupolas of conventional
cowpers it was necessary, owing to the heat stresses
suffered by the cupola, to adhere to certain strict condi-
tions as regards its geometrical design and to avoir aper-
tures as far as possible, in order to increase its static
~trength, there will hence forward be a greater degree of
~6~637
g
freedom in the selection of the geometrical shape of the
arch described in the foregoing, i.e. it can be given any
shape which proves most suitable and the necessary aper-
tures can be provided therein. It is thanks to this cir-
cumstance tha-t numerous variants can he adopted, some of
which will be descrlbed hereinafter, by reference to the
following f:igures.
Figures 2 and 2a illustrate one embodiment ln which
the hot air outlet 40 is provided in the centre of the arch,
above the checkerwork shaft 12. Instead of providing one
single burner, as in Figure 1, four burners 42a, 42b, 42c
and 42d are provided, each of exactly the same design as
the burner 22 but of a smaller size. These burners are
arranged in a "square" at regular intervals around the
hot air outlet 40. These burners 42a, 42b, 42c and 42d
will preferably be inclined at a slight angle in relation
to the longitudinal axis o~ the shaft, so that the thermal
radiation cone of each burner will come in contact with the
entire upper surface of the checkerwork shaft. The shape
and the angle of inclination of the apertures in the
brickwork of the arch 44 will naturally be in accordance
with thQ angle of inclina-tion of the burners.
In the version shown in Figures 3 and 3a the arch
54 has been provided with four burners 52a, 52b, 52¢ and
52d (not shown). These burners 52a, 52b, 52c and 52d are
identically similar to those of Figure 2 but arranged
differently. As may be seen, the hot air outlet 50 is no
longer in the centre of the arch but by the side of the
latter, while the four burners 52a, 52b, 52c and 52d are
arranged in a "square" around the centre of the arch 54.
Figures 4 and 4a illustrate a version analogous to
that of Figures 1 and la, with a same burner 22 positioned
in the centre of an arch 63 and with a hot air outlet 20
positioned adjacent to the burner 22. The difference in
relation to the verslon shown in Figure l resides in the
fact that the arch 63 no longer constitutes a ~rickwork
assembly and that the internal refractory lining 67 is
affixed by means of securing bricks 65 to the external
cladding 69 of the arch 63. This enables a flatter cons-
3~
- lQ -
truction to be adopted for the arch 63, i.e. the burner 22
to be positioned more closely to the upper surface of the
checkerwork shaf-t 12, thus in-tensifying the advantages which
result from thi~ adaptation in shape, as described in the
foregoing.
Needless to say, the versions shown in Figures l
to 3, can also be designed with an arch "hooked on", as
shown in Figure 4. These variants, however, will no longer
be described in detail.
Figures 5 and 5a illustrate a version with four
burners 64a, 64b, 64c and 64d, mounted inside the head 60
of a cowper immediately above the checkerwork shaft 62.
These burners are mounted vertically on a supporting slab 66
positioned transversely above the upper surface of the
lS shaft 62. The burners are arranged symmetrically in a square
around a central outlet 68 which rises vertically through
the slab 66.
Needless to say, the burners 64a, 64b, 64c and 64d
are of the type described previously, the associated aper-
2Q tures in the slab 66 being adapted to the heat radiation
cone of the burners, so that the entire upper surface of the
checkerwork shaft 62 will be subjected to the heating and
to the combustion gas.
The supply to the four burners 64a, 64b, 64c and
64d is effected by means of two main circular pipes 70 and 72
positioned around the head 60 and conveying the combustion
air and the combustible gases respectively to the said
burners. Each of the four burners is connected to the two
circular pipes 70 and 72 via radial pipes 74 and 76, each
provided with a shut-off gate 78 and 80.
The head 60 of the cowper is closed by a hermetic
casing 82 provided with the inlets 84 required for inspection
and replacement of the burners and deining a chamber 86
above the slab 66~ This casing 82 thus renders the cowper
head hermetic to the outside. This chamber 86 will prefer-
ably be cooled by the circulation of a suitable cooling
fluid, as will be described in greater detail hereinafterO
Figure 6 irst of all shows a variant of the version
illustrated in Figures 5 and 5a. In this embodimen-t of the
63~
invention there are once again four burners 94a, 94b (not
shown), 94c and 94d, mounted with a rim-type configuration
on a slab 96, above the checkerwork shaft 92 and inside
the head 90 of the cowper. The essential difference
between this embodiment and trhat ~hown in F~gures 5 and Sa
resides in the fac~ that the hot air outlet 98 i8 provided
in the side wall between the slab 96 and the upper surface
of the refractory checkerwork 92.
The supply of combustible gas to the burners is
again effected by a circular pipe 102 which is provided
around the head 90 and which is connected via radial pipes
104 and a shut-off gate 106 to each of the burne~ 94a, 94b,
94c and 94d. Contrary to the previous embodiment, however,
the combustion air is supplied through a pipe 100 penetra-
ting vertically and axially into the head 90 and connected
to each oE the burners via stubs 108. The head 90 is again
closed by means of a hermetic casing 110 comprising aper-
tures 112 afording access to the burners, and defining a
chamber 116 which can be cooled.
A casing 110 and also the casing 82 (Figure 5) are
provided with one or ~ore apertures 114 as a means of
regulating the pressure and circulation inside the head,
in the chamber formed by the casing 110 and the supporting
slab 96 of the burners.
~Figure 6 shows, likewise schematically, in thick
line.s, an advantageous constructional version for the cool-
ing and for the equalization cf the pressure, particularly
the pressurization, of the chamber 116.
For the ventilation of the chamber 116 the apertures
114 are connected with the external atmosphere via a pipe
118 and a gate 120. The checkerwork shaft 92 is likewise
connected to the exterior via a pipe 122 and a gate 124,
leading into a pipe 128 provided at the base of the checker-
work shaft 92, the combustion fumes normally emerging through
the said gate during the heating of the shaft.
The combustion air supply pipe 100 for the burners
communicates with the interior of the chamber 116 via a
number of apertures 130, preferably four, these apertures
130 being preferably provided with regulating valves shown
~6~63~
- 12 -
schematically at 132.
The cold air inlet orifice at the base of the
checkerwork shaft 92 is shown schematically by the reference
number 134 and is fed from a main pipe 136 via a gate 142~
~ 5 This main pipe 136 for the cold air likewise communicates,
: via a gate 149, a pipe 138 and a regulating valve 143, with
the pipe 100 through which the combustion air is intro-
duced into the burner.
At the beginning of each combustion phase or heating
phase for the shaft 92 both the chamber 116 and the in-
terior of the shaft have to be ventilated, since these en-
closures, during the preliminary phase, were under pressure.
For this purpose all that is required is to open the gates
120 and 124 in order to cause the air to emerge, expanding
in the process to atmospheric pressure, from the chamber 116
and the shaf-t 92, via the pipes 118 and 112 respectively.
Duriny the combustion period the interior of the
chamber 116 is cool.ed by causing some of the combustion
air penetrating through the pipe 100, via the apertures 130
and the regulating valve 132, to emerge through the aper-
tures 114.
At the end of the combustion period and before the
air period, i.e. the introduction of cold air via the ori-
fice 134 at the base of the checkerwork shaft 92, the cham-
ber 116 has to be pressurized in order to adapt the pressure
in the said chamber 116 to that of the air in the checker-
work, and the said pressure may rise to as much as 6 bars.
This equalizatlon of pressure is advantageously effected
by placing the main pipe 136 in commmunication not only
with the interior of the checkerwork 92, via the gate 142,
for the introduction of cold air into the checkerwork 92,
but also with the interior of the chamber 116, via the
valve 140, the pipe 138, the pipe 100, the apertures 130
: and the regulating valves 132. The pressurization of the
chamber 116 and tha-t of the shaft 92 will thus proceed
: parallel with each other, and the pressure differences
between one side of the slab 96 and the other will be
practically nill thxoughout the entire period when the
shaft 92 is being filled.
37
- 13 -
In order to prevent the cold air for the equalization
o~ the pre~sure in -the chamber 11~ from penetrating the
shaft 92 via the burners, valves indicated schematically
by the ~eference number 133 are provided between each o~
the burners 9~a, 94b, 94c and 9~d and the admission pipe 100.
The cooling of the chamber 116 throughout the
period when the cold air is being heated, this being known
as the aix period, will be effected in similar fashion to
the pressuri~ation and following this latter operation. In
other words, during the introduction of cold air via the
orifice 134 and the main pipe 136, a certain quantity of
air will be deflected via the gate 149, the valve 140, open
to a greater or lesser extPnt for the purpose, and the
pipe 13~3, towards the interior of the chamber 116. In order
to ensure the required circulation and cooling in this
latter, the air, heated in this manner, in the chamber 116,
is evacuated through -the apertures 114 and the pipe 118 to
the atmosphere. Duriny the cooling the valves 132 are set
to ensure that the circulation in the chamber 116 will
maintain a substantially constant pressure equal to that
obtained during the preliminary pressurization.
Instead of evacuating the air to the atmosphere
via the apertures 114 and the gate 120, the pipe 118 can be
connected to the pipe 122, as shown schematically by the
dotted lines 144, and this air can be returned via the
pipe 122 and the evacuation orifice 123 for the fumes to the
interior of the checkerwork shaft 92, where this air will
be mixed with the cold air introduced via the orifice 134.
This system provides a means of benefiting from the heating
of the air serving to cool the chamber 116, recuperating
the heat evacuated by the cooling. In this case, however,
an over-pressure device must be provided in the pipe 138,
in order to counteract the pressure lose oocuring in -the
cooling circuit.
In order to remedy any possible failure in the
cooling and pressurization circuit for the chamber 116, which
may be caused by faulty operation of the valve and which
may seriously aggravate the risk of accidents, the casing
110 should preferably comprise an aperture 146 connected
3L~6~6i3~
- 14 -
to a source of cold pressure gas such as nitrogen. A back-
up circuit of this kind will normally not be in operation
but will be caused to come into operation automatically as
soon as the temperature in the chamber 116 exceeds a certaîn
preselected threshold or the pressure in this cha~ber 116
falls below a cer-tain critical level.
The slab 96 may also be provided with a small aper-
ture connecting the chamber 116 to the interior of the
checkerwork shaft 92, thus providing an additional degree
of safety against an accidentally excessive pressure dif-
ference between the respective sides of this slab.
The process for the pressurization and cooling of
the chamber 116 may also be applied to the version shown -
in Figure 5, for the purpose of pressurizing and cooling
the chamber 86. In particular, the apertures 130 and the
regulating valve 132, provided in the pipe 100 in the case
of E'igure 6, are provided on the pipes 74 where Figure S
is concerned. A slightly modified system, which will be
described below by reference to E'igure 7, can likewise be
adopted.
In the said Figure 7, the components discussed by
reference to Figures 5 and 5a have been retained, the same
reference numbers being used again. This Figure 7 likewise
contains a reproduction of the general diagram provided in
conjunction with Figure 6, identical components being marked
with the same reference numbers. Contrary to the methodadopted
in the case of Figu. 6, however, the auxiliary pipe 138 for
th~e cold air leads both into the circular combustion air supply
pipe 70 and into an auxiliary circular pipe 148 connected by
one-or more small tubes 150 to the interior of the chamber 86.
During the combustion period so~e of the combustion
air introduced into the burners via the circular pipe 70
is deflected via the regulating valve 140 into the circular
auxiliary pipe 148 in order to be conveyed into the interior
of the chamber 86 for cooling purposes. The evacuation of
the air from the interior of the chamber 86 may on~e again
be effected via the apertures 114 and the pipe 118.
During the air period the e~ualization of pressure
in the chamber 86 and the cooling in the interior of this
~6~163~
- 15 -
latter are effected by introducing cold air via the pipe 138
into the circular auxiliary pipe 148 and conveying it from
the latter to the interior of the chamber 86. Supplementary
valves, not shown, can be provided in order to isolate the
circular pipe 70 from the pipe 138 during the combustion
period and the pipe 138 from the circular conduit 70 during
the air period. More complete information will be provided
by the description given with reference to Figure 6~ It
should be noted, however, that in the version shown in
Figure 7, a supplementary circuit 146 has likewise been
provided, serving to introduce additional cooling and
pressurization gas.
Needless to say, it is also possible for the example
shown in Figure 6 to be provided with the system for the
injection of cooling and pressurization air via a circular
auxiliary pipe, as in the case of Figure 7.
Figure 8 provides a schematic diagram of the upper
part of a cowper similar to that described by reference to
Figure 6, comprising a similar arrangement of burners 94a,
94b, 94c and 94d, and also a similar pressurization and
cooling system for the chamber 116. In order to illustrate
this variant, however, the apertures connecting the pipe 100
to the interior of the chamber 116 are shown at a higher
level, marked 152 in Figure 8. These apertures 152 are
naturally likewise provided with regulating valves, shown
schematically by the reference number 154.
Contrary to the preceding embodiment of the invention,
particularly that shown in Figure 6, the embodiment illus-
trated by Figures 8 and 8a comprises a slab 156 within which
is provided a cooling circuit consisting of an entire series of
tubes 158 sunk in the mass of the slab 156. In the diagrams
these tubes 158 are position~d parallel to one another, but
they can obviously be positioned differently, particularly
in a circle or spiral, in order to cover the entire surface
to be cooled. 'These tubes 158 are connected both to a main
distributor 160 and to a mani~old 164 connected to each of
the said tubes 158.
The cooling circui~ provided for the slab 156 and
shown in Figures ~ and 8a is designed to function with air.
- 16 ~ 37
It is thus of advantage to connect this cooling circuit of
the slab 156 to this circui-t through which combustion air
is supplied to a series of cowpers. It is known, in fact,
that installations for the production of hot air for blast
furnaces comprise a group of cowpers, i.e. at least two
cowpers operating alternately, one in the combustion period
and the other in -the air period, and then vice versa. One
common feed system is thus generally provided for supplying
the combustion air to each of the pipes 100 and each of
the cowpers. In the case of Figure 8, therefore, the
`~ cooling circuit of the slab 156 can be incorporated in the ~
combustion air supply, 50 that the combustion air passes ;
through the tubes 158 before penetrating the burners.
The manifold 16~ i9 connected via two pipes 168
15and 168' (see Figure 8a) each comprising a gate 170 (see
E'igure 8) to two combustlon air supply pipes 100 for two
cowpers.
When the cowper shown schematically in Figure 8 is
opexating during the combustion period the gate 170 is
open and the cooling air circulating in the tubes 158 is
introduced into the pipe 100 supplying combustion air to
the burners. On the other hand, when the cowpex changes
over to the air period the gate 170 is closed and the cool-
ing air for the tubes 158 is conveyed through the pipe 168'
to another cowper which at this moment is operating in
the combustion period. Consequently, in addition to the
pressurization and cooling of a chamber 116, which are
carried out in the normal manner~ as in the case of Figure 6,
the version shown in Figure 8 guarantees supplementary
cooling of the slab 156, both during the combustion period
and during the air period.
Figure 9 shows another variant applied to a cowper
of the type described by reference to Figure 6, this time
comprising a supplementary cooling system for the slab 96.
This supplementary cooling is effected by means of a flat
cooling chamber 172 provided specially for this purpose
immediately above the slab 96 and separating the latter
;from the interior o~ the chamber 116. This chamber 172
is connected via a pipe 174 and an over-pressure device 176
to -the auxiliary pipe 138, which latter, as in the version
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shown in Figure 6, connects the main pipe 136 for cold air
to the combustion air supply pipe 100. The outlet of -the
cooling chamber 172 is connected via a regulating valve
and a pipe 178 to the exhaust orifice 128 provided for the
fumes at the base of a cowper. In order to avoid a direct
passage from the inlet to the outlet of the chamber 172,
the latter is preferably subdivided into compartments in
order to form baffles and force the cooling air to circuit
throughout the chamber.
During the combustion period some of the combustion
;~ air circulating in the pipe 100 passes through the upper
part of the pipe 138 and is conveyed by the over-pressure
de~ice 176 into the cooling chamber 172. It is discharged
from the chamber 172 to the atmosphere via the valve 130,
the pipe 178 and the gate 124.
During the air period cold air is introduced into
the cool.ing chamber via the pipe 138, the over-pressure
device 176 and the pipe 174. Thi.s air circulating in the
cooling chamber 172 is pre:Eerably recycled via the pipe 178
and the orifice 128 in order to -take advantage of the heat
evacuated from the chamber 172.
n addition to the cooling of the chamber 172 the
pressurization and cooling o~ the chamber 116 are effected
in the same manner as in the case of Figure 6.
Needless -to say, the~cooling chamber 172 in the
version shown in Figure 9 can be replaced by a system of
cooling pipes as in the version shown in Figure 8. Conver-
sely, the system of cooling pipes provided in the version
shown in Figure 8 can be replaced by the cooling chamber
provided in the case of Figure 9.
Figures I0 and 10a illustrate a version analogous
; to that of Figure 8 but with a cooling system provided
inside the slab 156. As in the example shown in Figure 8,
a certain number of pipes 158 are accomodated in a mass of
the slab. These pipes are connected both to a distributor
182 and to a manifold 184. Contrary to the example shown
in Fi~ure 8, however, i~ is only cooling water that is
caused to circulate in the cooling circuit of the slab 156.
Needless to say, the pipe 158 can once again be positioned
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parallel to one another or in different configurations,
particularly circular or sp.iral, in order to cover the
entire surface of the slab 156. The cooling and pressur-
ization of the chamber 116 are again effected as in the
version shown in E'igure 6.
The different var.iants of the cooling system which
are shown in Figures 8, 9 and 10 have been deseribed in
eonjunetion with a eowper of the type diseussed by refer-
ence to Figure 6. It is nevertheless obvious that the
versions shown in Figures 8 - 10, as well as the processes
employed, are equally applicable to an embodiment such as
that shown in Figure 5 or in Figure 7.
Finally it should be noted that in the version
shown in Figure 10 the cireuit 158 can be replaced b~ a
eooling ehamber analogous to the ehamber 172 and again
serving for the cireulati.on of either water or some other
eooling liquid.
Figure 11 shows an advantageous example for the
design of -the head of a eowper, particularly applieable to
the versions shown in Figures 1-4, Figure lla being a view
of the upper part of a cowper looking downwards. In this
example, there are four burners 190a, l90b, l90c and l90d,
mounted in a "square" around the centre of an arch 192, the
hot air outle-t 194 being provided at the side. In this
example the shape o~ the areh is better adapted to the
burners inasmueh as for eaeh burner the areh forms a eavity
196 fitting the refraetor~v part of the burnersl and forming
an extension thereto, thus eombining with them to form the
eombustion bowl 198.
A set of criss-cross beams 200, 202, 204, integral
with the cladding of the arch 192, supports both the latter
and the burners.
Figures 12 and 12a show how the assembly illustrated
in Figures 10 and lOa is adapted to the versions shown in
Figures 5-10. The four burners 206a, 206b, 206e and 206d
are mounted on a slab 208 whieh, like the areh 192 in
Figure 11, eomprises eavities 210 which fit the shape of
the refraetory portion and whieh combine with this latter
to form combustion bowls 212. The slab 208 and the four
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burne.rs 206a, 206b, 206c and 206d are supported by beams.
These beams are supported in their turn by the external
casing 214 which forms a prolongation for the external
cladding of the shaft 92.
: :
.
