Stave for cooling of blast furnace walls and method of manufacturing same

In the structure of a stave for cooling carbon fire-bricks laid on a hearth side wall of a blast furnace, the stave arranged between the carbon fire-bricks on the hearth side wall and a shell is made of a rolled steel plate. The stave body is formed in such a manner that a cooling water passage is formed by drilling the steel plate directly, or the steel plate on which grooves are formed is joined onto another steel plate to be used as a cover. A cooling water feed port and a cooling water discharge port are provided on the outside of the stave body, and these ports are connected to the cooling water passage.

TECHNICAL FIELD 
The present invention relates to a structure for cooling a blast furnace 
wall. More particularly, the present invention relates to a structure for 
cooling a hearth side wall, by which a high heat load section on the blast 
furnace wall can be intensely cooled so that the life of the blast furnace 
wall can be extended. Also, the present invention relates to a method of 
manufacturing a stave used in the cooling structure. 
BACKGROUND ART 
A blast furnace wall, in particular, the hearth side wall is the portion 
which determines the life of the blast furnace. Therefore, prevention of 
damage to carbon fire-bricks composing the hearth side wall is a most 
important item. The causes of damage to carbon fire-bricks laid on the 
hearth side wall are corrosion caused by molten iron and embrittlement 
caused by thermal stress. In order to prevent damage to carbon 
fire-bricks, it is most effective to intensely cool the high heat load 
section on the blast furnace wall. 
In respect of the method of cooling the hearth side wall of the blast 
furnace, there are provided two methods. One is a method of cooling the 
hearth side wall by circulating water in staves, and the other is a method 
of cooling the hearth side wall by spraying water on a shell of the blast 
furnace. 
In this case, explanations will be made of a structure of the hearth side 
wall equipped with common staves for cooling. As shown in FIG. 1, carbon 
fire-bricks 4 are layered on the inside of the blast furnace. Between the 
layer of carbon fire-bricks 4 and the shell 1, there are provided stamping 
refractories 3, staves 5 and castable refractories 2. On a bottom hearth 
portion T of the blast furnace, fire-bricks 12 are layered, and cooling 
pipes 13 are arranged on the bottom hearth portion T. Therefore, the 
hearth side wall R of the blast furnace is cooled by the staves 5, and at 
the same time, the bottom hearth portion T is cooled by the cooling pipes 
13. Reference numeral 10 is a tap hole. 
As the conventional staves 5, a stave 6 made of cast iron shown in FIGS. 2A 
and 2B is mainly used. This stave 6 is composed in such a manner that the 
stave pipes 7 having cooling water passages 15 are cast at predetermined 
intervals. In order to prevent the occurrence of carburizing caused in the 
process of casting and also in order to reduce a thermal shock, the stave 
pipe 7 is coated with marshite 8 which functions as a heat insulating 
layer. In the stave pipe 7, there are provided a water feed pipe 14a for 
feeding cooling water and a water discharge pipe 14b for discharging 
cooling water. 
The hearth side wall of the blast furnace is cooled when cooling water 
flows in the stave pipe 7 and also when heat is radiated from the shell 1. 
However, a quantity of heat not less than 95% of the heat to be removed 
from the side wall is taken away by cooling water flowing in the stave 
pipe 7. Accordingly, in order to enhance the cooling capacity for cooling 
the hearth side wall, it is effective to reduce a heat resistance between 
the carbon fire-bricks 4 and cooling water in the stave 6. 
For this reason, improvements have been made to enhance a coefficient of 
thermal conductivity (inverse number of heat resistance) between the 
carbon fire-bricks 4 and the stamping refractories 3. Therefore, the 
cooling capacity for cooling the hearth has been enhanced. 
However, the heat resistance of marshite 8 coated on the surface of the 
stave pipe 7 in the stave 6 made of cast iron is very high. Therefore, 
this increase in the heat resistance of the stave 6 made of cast iron has 
been a problem to be solved. 
In order to solve the above problems, Japanese Unexamined Patent 
Publication (Kokai) No. 6-158131 discloses a technique in which the 
cooling pipe is made to come directly into contact with the stamping 
refractories 3 or the carbon fire-bricks 4. According to this method, the 
thermal resistance of the stave 6 made of cast iron can be eliminated. 
Therefore, the heat resistance between the carbon fire-bricks 4 and the 
cooling water flowing in the cooling pipe can be reduced. 
However, the following problems may be encountered in the above cooling 
system. The above cooling system is unlike the conventional stave cooling 
system in which the surface of the stave 6 made of cast iron is contacted 
with the surfaces of the carbon fire-brick 4 via the stamping 
refractories. Accordingly, in the above cooling system, when the carbon 
fire-bricks 4 are expanded in the operation of the blast furnace, due to a 
difference of thermal expansion between the carbon fire-bricks 4 and the 
shell 1, the cooling pipe is compressed, so that the cooling pipe or the 
carbon fire-bricks 4 are damaged, or alternatively a gap is caused between 
the cooling pipe and the carbon fire-bricks 4, so that the heat resistance 
is increased. As a result, the reliability of the installation is 
deteriorated. 
In other words, as compared with the time at which the blast furnace was 
constructed, when the blast furnace is operated for production, a gap more 
than several tens of mm is caused between the carbon fire-bricks 4 and the 
shell 1. This difference of thermal expansion is absorbed by the 
contraction of the stamping refractories 3 in the conventional stave 
cooling system. However, according to the invention disclosed in Japanese 
Unexamined Patent Publication (Kokai) No. 6-158131, no consideration is 
given to this point, and there is such a problem as the cooling pipe and 
the carbon fire-bricks 4 are damaged and as the heat resistance is 
increased. 
Japanese Unexamined Patent Publication (Kokai) No. 55-122810 discloses a 
technique, which will be described as follows. The stave body is composed 
of a plate made of copper or copper alloy, the heat conductivity of which 
is good. A plurality of holes are formed by drilling in the longitudinal 
direction of the plate, and the end openings are closed up. After that, 
connecting ports for connecting the cooling water pipes are formed on the 
back side of the plate. The above stave cooling system is adopted for a 
shaft portion of the blast furnace. 
When the above stave is applied to the shaft portion of the blast furnace 
in which the fluctuation of a heat load caused by gas in the blast furnace 
is directly imposed on the stave, the efficiency is high because the 
cooling capacity of the stave is large and further no carburizing of 
copper is caused by the carbon contained in the blast furnace gas. 
However, on the hearth side wall of the blast furnace, it is presupposed 
that the carbon fire-bricks 4 must remain inside the blast furnace. 
Accordingly, the stave is cooled via the front carbon fire-bricks 4 and 
the stamping refractories 3. Due to the heat resistance of these portions, 
even if the coefficient of thermal conductivity of the base metal of 
copper is high, the overall coefficient of thermal conductivity is not so 
high, that is, the cost is increased too much with respect to the 
improvement in the cooling capacity. In the structure of the stave 
disclosed in the above patent publication, it is necessary to provide a 
cooling water feed port and a cooling water discharge port for each 
cooling water passage in the longitudinal direction of the plate composing 
the stave. Accordingly, the number of pipe attaching sections to be 
connected with the cooling water feed port and the cooling water discharge 
port is increased. Therefore, the number of openings formed on the shell 1 
is greatly increased in the case of installation of the stave. 
Accordingly, the above stave is disadvantageous in that the shell 
thickness is increased and the number of gas sealing portions to seal up 
the openings is increased. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an inexpensive and 
reliable structure for cooling a blast furnace side wall by enhancing the 
cooling capacity to cool a high heat load section. Also, it is an object 
of the present invention to provide a method of producing a stave used for 
the structure for cooling a blast furnace wall. 
In order to solve the above problems, the present invention is to provide a 
structure for cooling a hearth side wall of a blast furnace characterized 
in that: a steel plate, for example, a rolled steel plate is machined, so 
that a cooling water passage is formed on the steel plate; a cooling water 
feed port and a cooling water discharge port, which are respectively 
connected to the cooling water passage, are provided on the steel plate; 
and the thus formed stave is arranged between carbon fire-bricks on the 
hearth side wall of the blast furnace and the shell. 
Also, the present invention is to provide a stave in which a cooling water 
passage is formed by drilling a rolled steel plate. 
Moreover, the present invention is to provide a stave characterized in 
that: a cooling passage is formed by means of machining on at least one of 
the surfaces of a rolled steel plate; and this rolled steel plate is 
joined to another rolled steel plate which has not been machined. 
Furthermore, the present invention is to provide a method of producing a 
stave for cooling a blast furnace wall, comprising the steps of: forming a 
plurality of blind holes by drilling a rolled steel plate in the 
longitudinal direction; closing up end portions of the blind holes by 
plugs; forming blind holes on the rolled steel plate by drilling from the 
short sides at both end portions in the longitudinal direction of the 
rolled steel plate so that the blind holes can cross the blind holes in 
the longitudinal direction or alternatively the blind holes can penetrate 
the plugs; and closing up the end portions of the blind holes by plugs, so 
that a plurality of C-shaped cooling water passages can be formed in the 
rolled steel sheet. 
Moreover, the present invention is to provide a method of producing a stave 
for cooling a blast furnace wall, comprising the steps of: drilling a 
plurality of through-holes from both end portions of a rolled sheet in the 
longitudinal direction; closing up both end portions by plugs; and forming 
connection passages for connecting the cooling water passages in the 
longitudinal direction with each other, at positions adjacent to closing 
portions of the ends of the cooling water passages in the longitudinal 
direction, so that a plurality of C-shaped cooling water passages can be 
formed in the rolled steel sheet. 
Due to the stave structure of the present invention described above, it is 
possible to enhance the cooling efficiency of the stave and reduce the 
heat resistance. Further, it is possible to extend the life of a high heat 
load portion by a simple stave cooling structure.

BEST MODE FOR CARRYING OUT THE INVENTION 
FIG. 3 is a view showing a state in which the stave 16 composed of a 
drilled steel plate, which is an example of the present invention, is 
incorporated onto the hearth side wall R. 
The stave 16 is composed as follows. The stave base metal 9 made of a steel 
plate is drilled. The thus formed hole is used as a cooling water passage 
15. At both end portions of the cooling water passage 15, there are 
provided a cooling water feed pipe 14a and a cooling water discharge pipe 
14b. These cooling water pipes 14a, 14b penetrate the shell 1 and the 
castable refractories 2, and connect with a water supply located outside 
the blast furnace. FIGS. 4A to 4D are views showing the stave in detail. 
FIG. 4A is a front view of the stave 16 made of a steel plate. The stave 
base metal 9 is rectangular. As shown in FIG. 4D, the cooling water 
passage is composed of three cooling water passages 15 which are combined 
to form C-shapes. This cooling water passage will be referred to as a 
water passage, hereinafter. The water feed pipe 14a and the water 
discharge pipe 14b are respectively connected with both end portions 15-1, 
15-2 of the water passage. 
The reason why the water passage is formed into a C-shape as described 
above is that each water passage is made independent so as to make a flow 
of water in the stave uniform and that the number of the openings on the 
shell is made small. 
FIGS. 5A to 5D are views showing another example of the stave made of a 
steel plate of the present invention. As shown in FIGS. 5B and 5C, this 
stave 16 is composed as follows. The stave base metal 9 is divided into 
two members. On the surface of the thick steel plate 9-1, four grooves are 
formed by means of machining. These four grooves are used as water 
passages 15. On the surface of the thick steel plate on which the water 
passages 15 are formed by means of machining, the thin steel plate 9-2 is 
overlapped together. The entire circumference on which the two steel 
plates are joined to each other is subjected to welding all around (shown 
by reference character M in FIG. 5D), and further the centers of the two 
steel plates are fastened by bolts 17. 
The thin steel plate 9-2 is drilled at positions corresponding to both end 
portions 15-1, 15-2 of the water passage 15, so that the water feed port 
and the water discharge port are provided at these drilled positions. The 
water feed pipe 14a and the water discharge pipe 14b are respectively 
inserted into these ports, and these water pipes are connected with the 
water passage 15. 
In this type stave, it is possible to form a water passage arbitrarily. 
Therefore, it is possible to reduce the number of the water feed ports and 
the water discharge ports compared with the stave shown in FIG. 4. 
Accordingly, the number of the openings formed on the shell can be further 
reduced. 
Next, referring to FIG. 6, a method of producing this steel plate drilling 
type stave will be explained below. In this example, there are four sets 
of C-shaped water passages in the stave. 
First, in the upper portion of the stave base metal 9 in the longitudinal 
direction, two blind holes 15a, 15a are formed which extend from the left 
short side surface S, and also two blind holes 15e, 15e are formed which 
extend from the right short side surface S. Next, a blind hole 15b is 
formed which extends from the upper long side L of the stave base metal 9 
to the blind end portions of the above blind holes 15e, 15e. This blind 
hole 15b is a hole to communicate the blind holes 15e, 15e with each 
other. Next, in the same manner as that described above, a blind hole 15c 
is formed which extends from the upper long side L of the stave base metal 
9 to the blind end portions of the above blind holes 15a, 15a. This blind 
hole 15c is a hole to communicate the blind holes 15a, 15a with each 
other. 
Next, the opening end portions of the blind holes 15a, 15a are closed up by 
the plugs 18a, 18a at the positions 15-1, 15-2 which are the water passage 
end portions. In order to insert the plug 18b into the blind hole 15b, the 
plugs 18a, 18a are drilled again. After that, the opening end portion of 
the blind hole 15b connecting the blind holes 15e is closed up by the plug 
18b. In the same manner, the opening end portion of the blind hole 15c 
connecting the blind holes 15a is closed up by the plug 18d. The opening 
end portions of the blind holes 15e, 15e are closed up by the plugs 18c at 
the positions 15-1, 15-2 which are end portions of the water passage. 
In the manner described above, two sets of C-shaped water passages 15, 15 
are formed in the upper portion of the stave base metal 9. 
In the same manner as that described above, two sets of C-shaped water 
passages 15, 15 are formed in the lower portion of the stave base metal 9. 
In this connection, it is preferable that the plugs 18a to close up the 
blind holes formed first are tapered so that they can not be moved when 
the blind hole 15b is drilled. 
A horizontal section of the bottom of the blast furnace is circular. 
Therefore, it is necessary that the rolled steel plate, on which the above 
C-shaped water passages are formed, is curved in accordance with the 
radius of curvature of the inner surface of the shell so that an interval 
between the stave and the shell can be maintained constant. 
FIGS. 7A and 7B are views showing a stave having blind holes formed by the 
method explained in FIG. 6. At positions on the surface of the stave base 
metal corresponding to the blind hole end portions 15-1, 15-2, holes are 
formed by means of drilling in a direction perpendicular to the surface of 
the drawing, so that the water feed port 19 and the water discharge port 
20 are respectively formed. After that, the stave body 16 is curved as 
shown by FIG. 7A in accordance with the radius of curvature of the inner 
surface of the shell. The water feed pipe 14a and the water discharge pipe 
14b are arranged at the water feed port and the water discharge port via 
the water pipe mounts 21. 
As shown in FIG. 8, the hearth side wall of the blast furnace is inclined. 
When the inclination angle .theta. of the furnace wall is approximately 
perpendicular, it is possible to apply the producing method shown in FIG. 
6. However, when the inclination angle .theta. is small, the developed 
shape of the stave becomes a sector-shape. Accordingly, it is impossible 
to maintain the dimensional accuracy of the water passage in the 
longitudinal direction when the stave is produced by the producing method 
shown in FIG. 6. 
FIGS. 9A to 9C are views showing a comparison of the formation of the water 
passage in the longitudinal direction when different drilling methods are 
adopted in the case of the inclination angle .theta.=75.degree.. In each 
view, there is shown a distance from the base C of the sector to the water 
passage in the longitudinal direction when the length of the side A is 100 
cm and the water passage in the longitudinal direction is formed at a 
position distant of 10 cm from the lower end of the side A. Preferably, 
the distance from the base side C of the sector to the water passage in 
the longitudinal direction is constant at any position because it is 
possible to improve uniformity of cooling the stave due to constancy of 
the distance. 
FIG. 9A is a view in which the water passage in the longitudinal direction 
is formed by the method illustrated in FIG. 6 and the blind holes are 
horizontally formed by means of drilling. According to this method, even 
if the drilling is conducted perfectly, a difference of the distance 
between the center of the sector and the peripheral portion of the sector 
is as large as (12.55-10)=2.55 cm. In this example, an angle formed 
between the drilling direction and the side A is 92.33.degree., which is 
not perpendicular to the side A. Therefore, it is difficult to set a drill 
tool to the intended direction. Accordingly, from the practical viewpoint, 
it is impossible to conduct drilling with high accuracy. 
FIG. 9B is a view showing a method by which the above problems relating to 
accuracy of drilling direction can be solved when the stave is drilled. 
According to this method, drilling is conducted so that the drilling 
direction is perpendicular from both sides to the side A. In this case, a 
difference of the distance between the center of the sector and the 
peripheral portion of the sector is (7.45-10)=-2.55 cm. That is, the 
difference of the distance is substantially the same as that of the method 
shown in FIG. 9A. However, according to this method, a problem such as 
unstability of the drilling direction cannot be occurred. 
FIG. 9C is a view showing a method by which a distance from the base C of 
the sector to the water passage in the longitudinal direction is minimized 
at each position when the water passage in the longitudinal direction is 
formed. One point is determined on the side A in such a manner that a 
distance from the lower end of the side A to the point is 10 cm, and 
another point on the center line is determined in such a manner that a 
distance from the lower end of the center line to the point is 10 cm. A 
virtual line is drawn between these two points. Sides A', A' are 
determined so that the sides A', A' can become perpendicular to this 
virtual line. Then, the stave base metal is cut into a sector along the 
sides A', B, A' and C. 
In the above stave base metal, the water passage in the longitudinal 
direction is formed in such a manner that the stave base metal is drilled 
from both end surfaces in a direction perpendicular to the sides A', A' 
and the thus formed holes are penetrated to each other at the center. 
After that, in order to remove redundant portions of the sides A', the 
stave base metal is cut again along the sides A, A. Then, both ends are 
closed up by plugs. According to this method, a difference of the distance 
between the base C of the sector and the water passage in the longitudinal 
direction is (10.85-10)=0.85 cm at the maximum. Therefore, the difference 
of the distance can be greatly improved by this method compared with the 
method explained in FIG. 9B. 
The above explanations have been made when the inclination angle .theta. is 
75.degree.. Of course, when the inclination angle .theta. is larger than 
75.degree., the stave base metal may be drilled by the method shown in 
FIG. 9(A) or 9(B). 
Next, a specific example is shown in FIG. 10, in which a stave made of a 
steel plate used for a blast furnace, the inclination angle of which is 
.theta.=75.degree., is manufactured by the method shown in FIG. 9C. 
First, the stave base metal 9 is cut out into a sector along the sides A', 
A', B and C shown in FIG. 9C. Then, the stave base metal is drilled from 
the sides A', A' in directions perpendicular to the sides A', A' by the 
drilling method shown in FIG. 9C. The thus formed holes penetrate each 
other at the center, so that the through-hole 15f in the longitudinal 
direction can be formed. This drilling method is adopted to the overall 
stave base metal, and nine through-holes in the longitudinal direction are 
formed. 
Then, the stave base metal is cut out along the sides A, A, so that the 
stave base metal of the predetermined dimensions can be obtained. All 
openings on both end portions of the through-holes 15f in the longitudinal 
direction are closed up by the plugs 18. 
Next, a connecting groove 15g to connect the two through-holes 15f, 15f in 
the longitudinal direction is formed at a position close to the 
through-hole closing section by means of cutting conducted on the surface 
of the stave base metal 9. After that, an opening section on the surface, 
which has been made by cutting, is closed by a cover 22. 
In this way, three through-holes in the longitudinal direction are 
connected with each other, and one set of C-shaped water passage 15 can be 
composed. In the view, three sets of C-shaped water passages 15 are shown. 
Then, in the same manner as that shown in FIGS. 7A and 7B, the stave base 
metal is drilled to form the water feed port 19 and the water discharge 
port 20; the stave body is curved in accordance with the radius of 
curvature of the inner surface of the shell; the water feed pipe and the 
water discharge pipe 14 are attached; and the water feed pipe mount and 
the water discharge pipe mount 21 are attached. In this way, the stave can 
be produced. 
Due to the foregoing, in the same manner as that of a blast furnace having 
a perpendicular wall, even in the case of a blast furnace having an 
inclined wall, it is possible to produce an inexpensive and reliable stave 
by which the cooling capacity can be enhanced to cool a high heat load 
section of the blast furnace. 
As described above, in the stave made of a rolled steel plate of the 
present invention, the cooling water passage is directly formed on the 
rolled steel plate by means of machining. Therefore, it is unnecessary to 
provide a marshallite layer, the heat resistance of which is high. 
Further, the cooling water passage can be formed with high accuracy by 
machining. Accordingly, the pipes are not moved in the process of casting, 
so that intervals of the cooling water passages can be shortened and 
thickness of the stave base metal can be reduced. As a result, the heat 
resistance of the overall stave can be decreased. In the method of the 
present invention, machining is conducted on a rolled steel plate, the 
cost of which is low, and it is unnecessary to conduct processing on pipes 
and it is also unnecessary to conduct casting. Accordingly, the producing 
cost is lower than that of the conventional stave. 
EXAMPLE 
Under the condition that the thickness of the residual carbon fire-bricks 4 
was 0.5 m, the cooling capacity was 31138 kcal/m.sup.2 .multidot.h in the 
case of the conventional stave 5 made of cast iron in which the thickness 
of the stave was 160 mm and the pipe interval was 138 mm. On the other 
hand, in the case of the stave 16 made of a rolled steel plate of the 
present invention shown in FIGS. 4A to 4D, the dimensions of which were 
the same as those described above, it was possible to obtain a cooling 
capacity of 33038 kcal/m.sup.2 .multidot.h, that is, it was possible to 
enhance the cooling capacity by about 6%. Since the machining accuracy of 
the stave made of a rolled steel plate was high, it was possible to reduce 
the thickness of the stave and shorten the interval of the cooling water 
passages 15. When the stave thickness was changed to 100 mm and the 
interval of the cooling water passages 15 was changed to 100 mm, the 
cooling capacity was increased to 33851 kcal/m.sup.2 .multidot.h, that is, 
the cooling capacity was enhanced by about 10% compared with the cooling 
capacity of the cooling structure of the conventional stave made of cast 
iron. 
INDUSTRIAL APPLICABILITY 
As described above, when the stave made of a steel plate according to the 
present invention is used, the following effects can be provided. When the 
cooling water passage is formed into a C-shape on the steel plate, the 
number of the water feed ports and the water discharge ports and the 
number of the openings on the shell can be reduced to a half or less of 
those of the conventional stave. Further, the stave of the present 
invention can be produced by conducting an inexpensive rolled steel plate 
to machining and bending. Unlike the conventional stave made of cast iron, 
it is unnecessary to conduct processing of producing pipes and casting. 
Therefore, the producing cost of the stave of the present invention is 
lower than that of the conventional stave made of cast iron. 
The thermal expansion of carbon fire-bricks caused in the process of 
operation is absorbed by the stamping refractories, and a generated force 
is not concentrated at a specific portion since it is received by the 
overall surface of the stave. Accordingly, the cooling water passages and 
the carbon fire-bricks are not damaged. Therefore, from the viewpoint of 
strength property, it is possible to provide the same reliability as that 
of the conventional hearth side wall structure. 
The dimensions of one stave of the present invention are substantially the 
same as those of the conventional stave made of cast iron. Therefore, when 
the stave is attached onto the shell in the process of construction, an 
amount of work load is not increased, so that an increase in the 
construction cost can be prevented. 
As described above, the stave of the present invention can provide a higher 
effect than that of the conventional stave. Consequently, industrial 
applicability of the stave of the present invention is very high.