JPH0726310A - Protecting wall segment for iron shell of furnace body - Google Patents

Abstract

PURPOSE:To prevent the crack and the fall-off of a refractory from being caused by heat stress by forming a specific structure of an iron shell protecting wall segment between an outside iron shell and an inside refractory of a high temp. melting furnace, etc. CONSTITUTION:Heat insulating refractory material 5 is arranged inside of the outside iron shell 20 of a high temp. melting furnace, etc., and the protecting wall segment 10 provided with a cooling pipe 3 is interposed in the intermediate, and the refractory 5 at the furnace inner surface side thereof and the cooling pipe 3 for coolant passage at the furnace outer surface side thereof are integrally constituted with a metallic member 1. In this case, grains composed of ceramic material 7 are dispersed to the inner part of a refractory holding member 1a supporting the refractory 5 at the inner surface side. By reducing the heat conductivity of the refractory holding member 1a with the existence of this ceramic material 7, even when the temp. in the furnace rapidly varies, the large temp. difference between the refractory holding member 1a and the refractory 5 is not developed, and the development of crack caused by the heat stress can be prevented. Further, the fall-off of the refractory 5 is prevented and the protecting wall segment for iron shell of the furnace body capable of bearing against the long term use is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace body shell protecting wall segment which constitutes a furnace body shell protecting wall for protecting a furnace body shell of a high temperature melting furnace, a high temperature heating furnace or the like from a heat load from inside the furnace. It is about.

[0002]

2. Description of the Related Art Generally, a furnace wall of a high-temperature melting furnace, a high-temperature heating furnace, or the like, has a steel shell that structurally forms a furnace body, inside of which a high temperature part inside the furnace and a low temperature part outside the furnace are thermally controlled. It consists of a furnace wall that separates the furnace body. That is, the structure is such that the steel shell shares the strength of the structure as a structure and the protective wall shares the heat load from the inside of the furnace, and the two are mechanically coupled by, for example, bolting. This is because damage to the protective wall is most likely to occur due to long-term use, but in this case the furnace wall can be repaired by replacing only the protective wall segment that constitutes the protective wall, which saves the cost and time required. Is.

As a conventional furnace body iron skin protection wall segment,
For example, there is a protective wall segment for a blast furnace in which a refractory on the inner surface side of the furnace is sandwiched and supported by a plurality of refractory holding portions as disclosed in JP-A-61-37904. That is, as shown in FIG. 1, a plurality of refractory materials 5a and 5b are arranged on the furnace inner surface side of the protective wall segment 10,
A pipe 3 for forming a cooling passage is arranged on the outer surface side of the protective wall segment.

With such a structure, 1) the refractory on the inner surface side of the furnace can be made to have good heat insulation, and 2) the temperature of the metal part on the outer surface side of the furnace can be sufficiently lowered, and the outside thereof. The function as a protective wall that protects the furnace body iron shell 20 from the heat load from the inside of the furnace can be obtained.

Further, the conventional example shown in FIG. 1 has a structure in which a refractory, for example, a brickwork, is sandwiched by a part 1a of a metal member 1 which substantially constitutes a protective wall, and the shape is maintained. This will prevent the refractory bricks from falling off and enable long-term use of the protective wall.

[0006]

However, in the furnace shell protection wall segment according to the above-mentioned prior art, the refractory holding portion 1a and the refractory 5 having greatly different thermal conductivities on the inner surface of the furnace.
There are the following problems due to the contact of a and 5b.
That is, in the blast furnace, the temperature inside the furnace may change abruptly due to the dropping and moving of the charged raw materials and the high-temperature gas blow-through. At this time, the temperature of the refractory holding part is high in the thermal conductivity of the metal. Therefore, the temperature changes well following the temperature change in the furnace, but since the refractory has a low thermal conductivity, the temperature change becomes slow and a large temperature difference occurs between the two. This large temperature difference causes large thermal stress, which causes cracks at the interface between the refractory and the refractory holding part and in the vicinity thereof, and the refractory holding capacity of the refractory holding part is lost, resulting in relatively early fire resistance. The current situation is that they do not come out as expected because things fall out.

On the other hand, after the refractory has fallen off in this manner, the exposed area of the metal member having high thermal conductivity increases on the inner surface of the protective wall segment in the furnace, so that the inside of the furnace is excessively cooled. Therefore, there is a risk that the so-called furnace condition will fall into the condition that the temperature of the inner wall of the protective wall and the vicinity of the furnace will be reduced, the reduction of the powder inside the furnace, such as sinter, will be reduced and the air permeability in the furnace will be impaired. .

The present invention solves the problems of the protection wall segment of the prior art, that is, the cracking due to thermal stress, the dropping of refractory, and the problem of the poor reactor condition due to supercooling, and the protection that can withstand long-term use. Intended to provide a wall.

[0009]

In order to solve the above-mentioned problems, the present inventors have repeated experiments and trial manufactures and developed a new furnace body skin protection wall segment. The structure of the present invention as means for solving the problems is as follows.

In a furnace body iron skin protection wall segment comprising a refractory material on the inner surface side of the furnace and a metal member on the furnace body iron skin side and having a refractory material holding portion, the refractory material holding portion is inside the metal material. A furnace body shell protection wall segment, characterized by being composed of a composite material in which a ceramic material is dispersed in.

The method for manufacturing the furnace body iron shell protection wall is as follows. (1) A mechanism in which the refractory on the inner surface side of the furnace is arranged on the ceiling side, the cooling pipe forming the refrigerant passage is arranged on the ground side, and the ceramic material is prevented from floating above the upper side refractory material. A method of manufacturing a furnace body shell protecting wall segment, characterized in that a molten metal containing a ceramic material having a small diameter necessary for filling a space for forming a refractory holding portion is cast using a mold having the above.

(2) Using the mold described in (1) above,
After the ceramic material having a small diameter necessary for filling the space forming the refractory holding portion is put or placed in the mold in advance, the molten metal is cast into the furnace body shell protection wall segment. Production method.

(3) A mold in which a metal having a small-diameter ceramic material dispersed therein and a refractory are in contact with each other and cooling pipes forming a cooling passage are arranged separately from the metal and the refractory, respectively. A method of manufacturing a furnace body shell protection wall segment, characterized in that a molten metal is cast into the furnace body.

(4) Using a mold in which a refractory and a cooling pipe are arranged, a molten metal is cast, and then a metal part in which a separately manufactured small-diameter ceramic material is dispersed is sandwiched between the refractory. A method for manufacturing a furnace body skin protection wall segment, which is characterized by joining.

[0015]

[Operation] First, the structure of the furnace shell protection wall segment according to the present invention will be described. According to the present invention, as shown in FIG. 2, the refractory 5 is integrally formed on the furnace inner surface side of the protective wall segment 10 and the cooling pipe 3 forming a refrigerant passage is integrally formed on the furnace outer surface side by the metal member 1. It has a basic structure, and this basic structure is the same as the conventional technique. A feature of the present invention is that, as shown in FIG. 3, small-diameter particles of the ceramic material 7 are dispersed inside the refractory holding portion 1a supporting the refractory 5 on the inner surface side of the furnace. This refractory holding portion is a metal member 1 which substantially constitutes a protective wall segment.
Or a different metal.

This is to reduce the thermal conductivity of the refractory holding portion 1a and reduce the difference from that of the refractory 5. For example, assuming that the refractory holding portion 1a of the present invention is a material in which ceramic particles of SiO ₂ are dispersed in spheroidal graphite cast iron, the thermal conductivity of this material is SiO ₂ as shown by the solid line in FIG. The volume ratio decreases as the volume ratio of
At 0%, it is about 20% of that of spheroidal graphite cast iron. By greatly reducing the thermal conductivity in this way, it is possible to prevent a large temperature difference between the refractory holding portion 1a and the refractory 5 even if the temperature inside the furnace fluctuates rapidly, and it is possible to reduce the thermal stress. It is possible to prevent the occurrence of cracks.

However, what should be noted here is that the volume ratio of the ceramic particles is not determined only by the thermal conductivity but also by considering the strength characteristics. That is, the thermal conductivity decreases with the volume ratio as described above, but the tensile strength also decreases as shown by the broken line in FIG. 4, and thus the resistance to crack initiation decreases. For this reason, it is necessary to select the volume ratio such that the thermal conductivity and the tensile strength are appropriate. Spheroidal graphite cast iron and Si shown as an example
With the combination of O ₂ , the volume ratio of SiO ₂ is 40 to 50%.
Then, the strength of the resulting ceramic dispersion alloy is about 10
It is reduced to 0 MPa, and when it is incorporated into the furnace and exposed to the operating temperature, it is reduced to about 20 to 30 MPa.
If the strength is reduced below this value, the refractory cannot be held safely, so the upper limit of the volume ratio of SiO ₂ is preferably 40 to 50%.

In the above description, the combination of spheroidal graphite cast iron and SiO ₂ particles has been described, but the combination of metal and ceramic particles is not limited to this.
It can be appropriately selected depending on the temperature environment of the furnace wall to which the protective wall segment of the present invention is applied. For example, when the operating temperature is higher, a material having excellent high-temperature strength characteristics such as a Co-based heat-resistant alloy is used as the metal to be used, and when the temperature fluctuation in the furnace is large, it is more preferable as the ceramic particles. SiC, which has excellent thermal shock resistance, and conversely, when the temperature is relatively low, lower cost Al ₂ O ₃ particles can be used as the ceramic particles, respectively. Even in the case of combining different metals and ceramic particles in this way, it goes without saying that the appropriate volume ratio of the ceramic particles should be determined in consideration of the thermal conductivity and the strength as described above. That is not the case.

Next, the protective wall segment manufacturing method of the present invention will be described. In the present invention, since the method of casting a pipe is the most economical method for forming the refrigerant passage inside the furnace outer surface side of the protective wall segment, the basic structure of the protective wall segment is manufactured by the casting method. . At this time, the following four methods are appropriately adopted as a method of forming the refractory holding portion 1a of the metal member on the furnace inner surface side of the protective wall.

In the first method, as shown in FIG. 7, the molten metal 40 of the metal part is cast at the same time as the ceramic particles 7, and the fact that the specific gravity of the ceramic material 7 is smaller than that of the molten metal 40 is utilized. This is a method of forming a refractory holding part in which ceramic particles are dispersed. For this reason, the refractory 5 corresponding to the inner surface side of the furnace is arranged on the ceiling side, and the pipe 3 forming the refrigerant passage is arranged on the ground side, respectively, and the ceramic particles are prevented from floating above the upper portion of the refractory material on the ceiling side. A mold 30 having a mechanism 31 is used. At this time, as the ceramic floating suppression mechanism 31, for example, a porous sponge ceramic or a ceramic filter is used. This material may be one having heat resistance equal to or higher than the temperature of the molten metal to be cast, and may be the same as or different from the dispersed particles.

The molten metal 40 containing the necessary ceramic particles 7 for filling the refractory holding portion is poured into the mold 30 prepared in this way from the rivet, and the molten metal 40 and the runner 32 are cast. , To manufacture protective wall segments. At this time, in order to uniformly disperse the ceramic particles in the refractory holding portion, it is preferable to suppress the fluctuation of the molten metal surface by, for example, casting from the lower portion of the mold 3 by the down pouring method. This method has the advantage of the lowest cost. By such a casting method, the ceramic particles 7 have a smaller specific gravity than the molten metal 40, and thus float up and collect on the refractory holding portion 1a, where they are dispersed in the cast iron, and the cast iron solidifies as it is. This makes it possible to manufacture a protective wall segment in which the metal part 1 is made of spheroidal graphite cast iron only, and the refractory holding parts 1a, 1b are made of spheroidal graphite cast iron in which ceramic particles are uniformly dispersed.

The second method is, for the most part, the same as the first method, but it solves some problems in the casting operation in the first method. That is, in the first method, since the molten metal 40 containing the ceramic particles 7 is cast in advance, the ceramic particles may be caught in the middle of the casting runner 32 and may not flow into the mold 30.
Ceramic particles 7 are provided for each of the plurality of refractory holding portions 1a and 1b.
There may be cases where the number of fillings of the different.

In order to avoid this, in the present method, as shown in FIG. 8, the ceramic particles 7 necessary for filling the refractory holding portion 1a are previously charged into the mold 30 or the space for forming the refractory holding portion is formed. After placement, the molten metal 40 is cast to produce a protective wall segment similar to that obtained in Method 1 above. At this time, the ceramic particles 7 are placed in the mold 30.
The method of throwing in is effective in eliminating the above-mentioned problems and preventing clogging of the ceramic particles 7, that is,
In order to solve the above-mentioned problem of non-uniform filling of the ceramic particles 7 at the same time, it is preferable to arrange the ceramic particles 7 in advance in the space for forming the refractory holding portion.

The refractory holding portion is, for example, a cage made of a mesh made of metal wire or ceramic fiber, and ceramic particles are placed in the cage and suspended from above to be placed in the space. At this time, the metal wire melts and disappears due to the cast to form a part of the casting, but the ceramic fiber remains as it is in the casting.

When the high temperature molten metal 40 comes into contact with the ceramic particles 7, the ceramic particles 7 may be damaged by thermal shock, so it is preferable to preheat the ceramic particles 7. The preheating temperature varies depending on the thermal shock resistance of the ceramic particles used. For Al ₂ O _{3 having} low thermal shock resistance, SiC having high thermal shock resistance of 1200 to 1300 ° C. or higher.
Then, preheat to 500 to 600 ° C. or higher. Gas burner heating is the simplest preheating method. Thus, the manufacturing cost of the second method is slightly higher than that of the first method due to the higher cost for preheating.

The third method, as shown in FIG. 6, is to prepare the refractory holding portion 1a made of the ceramic particles 7 and the metal material in advance by casting or hot isostatic pressing (HIP method). There are features. In the first and second methods, the method for manufacturing the refractory holding portion 1a is limited to the cast-molding method simultaneously with the manufacturing of the protective wall segment, but the present method is not limited to this, and therefore the characteristic This produces an advantage that a more excellent refractory holding portion 1a can be obtained.

That is, since it is possible to select, as the metallic material to be used, a heterogeneous material having a higher heat resistance than the metal that substantially constitutes the protective wall segment, it is more durable than the protective wall segment produced by the first and second methods. An excellent protective wall segment can be manufactured.

In the first and second methods, a mechanism 3 for preventing the ceramic particles from floating above the upper part of the refractory on the ceiling side.
However, if a porous sponge ceramic or a ceramic filter is used as this mechanism, there is a restriction that only ceramic particles having a diameter larger than the diameter of the pores can be used. However, in this method, it is possible to use a ceramic material having a smaller particle size, for example, in the form of powder, and the filling volume ratio of the ceramic can be increased more than that when particles are used. The thermal conductivity can be further reduced.

When the HIP method using the metal powder and the ceramic powder is used in the production of the supporting metal portion, the thermal conductivity is reduced and the strength of the metal base material is improved as described above, and the protection having more excellent durability is obtained. It has the advantage of being able to manufacture walls. That is, a mixed powder of metal powder and ceramic powder is filled in a capsule, degassed in a vacuum, and hot isostatically processed at a temperature of 1300 ° C. and a pressure of 2000 atm, for example.

As another method, for example, as shown in FIG. 9, protection is performed by casting a molten metal by using a mold in which a prefabricated refractory holding portion and a refractory are arranged in contact with each other. The wall segment is manufactured by the cast-in-roll process.

The fourth method has the same advantages as the third method, but after the refractory-holding portion 1a of the metal portion is formed on the metal member 1 after being cast in the mold 30 as shown in FIG. It is characterized by mechanically joining to. This method is applied when the metal used for the refractory holding portion 1a and the metal used for casting are different, and particularly when the two metals are extremely brittle when they come into contact with each other at an extremely high temperature close to the melting temperature. It is effective when it is a combination that forms an intercalation compound. In this case, a high temperature joining method such as welding should not be used for joining the refractory holding portion and the metal member, and it is preferable to use a mechanical joining method such as bolting as shown in FIG. 6, for example. .

[0032]

EXAMPLES Next, examples of the present invention will be described. An example of the protective wall segment of the present invention is as shown in FIGS. 2 and 3. In this example, the uppermost and lowermost portions of the protective wall segment on the inner surface side of the furnace have the ceramic material 7 inside.
Is a refractory holding portion 1a having dispersed therein. FIG. 5 shows an example of another protective wall segment. In this example, the refractory holding portion 1b is provided in the central portion as well as the uppermost portion and the lowermost portion on the inner surface side of the protective wall furnace, thereby enhancing the refractory substance supporting effect. As described above, in the present invention, the number of refractory holding portions is not limited to two at both ends of the metal member, and any number may be provided in the middle thereof. Further, in the examples shown in FIGS. 2, 3 and 5, the refractory holding portion is metallurgically integrated with the metal member 1 of the main body. For example, as shown in FIG. They may be joined together physically.

Next, the performance of the protective wall segment of the present invention manufactured by the above method will be described. The protective wall segment having the structure shown in FIG. 5 was manufactured by the manufacturing method and materials shown in Table 1. At this time, the following was made the same for all protection walls.

Dimension of protective wall segment: width 1 m, height 1
m, thickness 400 mm ・ Refractory: fire brick, width 50 mm, width 100 mm, length 30
0 mm ・ Casting condition for metal part: Hot water temperature 1500 ° C, downward pouring ・ SiO ₂ particles: particle diameter 1 mm ・ SiO ₂ particles powder: 250 mesh powder

[0035]

[Table 1]

A thermal cycle test was conducted on the protective wall segment thus manufactured, and its durability was evaluated. The test conditions are shown below.・ Furnace inner surface environment: Repeated heating and cooling between maximum 1000 ℃ and minimum 200 ℃.・ Environment on the outside of the furnace: Leave it in the room temperature atmosphere. -Cooling on the outer surface of the furnace: Industrial water is flown through the pipe 3 at 10 l / min.・ Evaluation method: Visual inspection of the condition near the interface between the refractory holding part and the refractory on the inner surface of the furnace for each specified number of heating cycles. Table 2 shows the test results.

[0037]

[Table 2]

As can be seen from Table 2, the protective wall segment according to the prior art can be repeatedly cracked 10 times,
At 20 times, the refractory was partially peeled off and dropped off. On the other hand, the protective wall segment according to the present invention does not peel off the refractory material at least 30 times, and the durability is remarkably improved as compared with the prior art protective wall segment. In particular, the protective wall D has extremely excellent durability without cracking even after repeated use 40 times.

[0039]

As described above, according to the present invention, the problem of the prior art, that is, the problem of the furnace condition due to the dropout and supercooling of the refractory material, can be solved, and the furnace body iron that can withstand long-term use. A skin protection wall segment can be provided. Prolonging the life of the furnace body based on its long-term durability has an extremely large practical effect.

[Brief description of drawings]

FIG. 1 is a view showing a cross section of a protective wall segment for a blast furnace according to the prior art.

FIG. 2 is a diagram showing a cross-section of an embodiment of a furnace body shell protection wall segment according to the present invention.

FIG. 3 is an enlarged view of the vicinity of the refractory holding portion of the metal member in the protective wall segment of FIG.

FIG. 4 is a graph showing the effect of ceramic volume fraction on thermal conductivity and tensile strength.

FIG. 5 is a cross-sectional view of another embodiment of the furnace body shell protection wall segment according to the present invention.

FIG. 6 is an explanatory view showing an example of joining the refractory holding portion and the main body metal in another embodiment of the furnace body shell protecting wall segment according to the present invention.

FIG. 7 is an explanatory view showing one of the methods for manufacturing the furnace body protective wall segment of the present invention.

FIG. 8 is an explanatory view showing another one of the methods for manufacturing the furnace body protective wall segment of the present invention.

FIG. 9 is an explanatory view showing another one of the methods for manufacturing the furnace body protective wall segment of the present invention.

FIG. 10 is an explanatory view showing another one of the methods for manufacturing the furnace body protection wall segment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal member 1a, 1b Refractory holding part 3 Cooling pipe 5a, 5b Refractory 6 Double cut bolt 7 Ceramic material 10 Protective wall segment 20 Iron crust 30 Mold 31 Ceramic particle floating prevention mechanism 32 Runway 40 Molten metal

Claims (1)

[Claims] 1. A furnace body skin protection wall segment comprising a refractory material on the furnace inner surface side and a metal member on the furnace body steel skin side and having a refractory material holding portion, wherein the refractory material holding portion is made of a metal material. A furnace body skin protection wall segment characterized by being composed of a composite material in which a ceramic material is dispersed inside.