JP2932977B2 - Stave cooler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stove cooler for protecting, for example, a blast furnace or a reactor from heat load.

[0002]

2. Description of the Related Art For example, a water-cooled metal called a stave cooler for protecting a steel shell from a thermal load in a furnace is installed on the inner side of the furnace of a blast furnace. Conventionally, the recycle cycle of blast furnace is 7
~ 8 years, but steel companies have reduced renovation costs,
For the purpose of cost reduction such as reduction in production volume due to a stoppage, measures are taken to extend the life of the blast furnace, and as a result, the life of the blast furnace is prolonged by 15 to 20 years.

One of the measures for prolonging the life of the blast furnace is a technique for replacing a stave cooler. This technique replaces a damaged or worn stave cooler with a new stave cooler to protect the steel shell. Therefore, if the stove cooler is replaced regularly, the only factor that determines the life of the blast furnace is the amount of erosion (remaining thickness) of the furnace bottom brick, so that the life of the blast furnace can be greatly extended.

However, since the stove cooler has a configuration in which the main body of spheroidal graphite cast iron (FCD) or gray cast iron (FC) is water-cooled and the inside of the furnace is covered with a refractory material, there is a limitation on the service life. The material of the stave cooler was originally made of gray cast iron (FC). However, cracks due to lack of high-temperature oxidation in the furnace and low strength have occurred. Graphite cast iron (FCD
).

[0005] However, spheroidal graphite cast iron (FCD) is hardly cracked, but is subjected to thermal ratchet deformation due to high heat load (plastic deformation is accumulated, and excessive stress is applied to the cooling pipe embedded in the stave cooler body, resulting in breakage. And the life of spheroidal graphite cast iron (FCD) itself is limited to about 7 to 8 years.

[0006]

Therefore, as a new stove cooler, Japanese Patent Application Laid-Open No. Sho 59-7882 discloses a method of using gray cast iron (FC) as shown in FIG. A combination of a two-layer structure of vermiculite cast iron 1 and ordinary cast iron 2 having intermediate properties of spheroidal graphite cast iron (FCD) has been proposed.
No. 882 proposes that the vermiculite cast iron itself is inferior in abrasion resistance and strength at high temperature to higher than spheroidal graphite cast iron (FCD), so that it does not reach the present level.

[0007] Further, Japanese Patent Application Laid-Open No. 63-35708 shown in FIG.
In Japanese Utility Model Application Laid-Open No. 63-30333 shown in FIG. 5, molded refractories 3 are laminated on the inner surface side of the furnace of the stave cooler, and these refractories 3 are held by brick supporting hardware 4 made of heat-resistant steel. We are proposing something, but since the support hardware itself is thin,
When used in a high heat load area, a long life cannot be expected. Furthermore, because of the structure in which the refractories are laminated, the thickness of the stave cooler increases, and when the partial renewal is performed in place of the conventional stave cooler, the profile inside the furnace deteriorates, which causes deterioration of the furnace condition. Great potential.

[0008] In addition, in all three cases, if the refractory or the support metal inside the furnace is worn, a thermal load is directly applied to the stave cooler main body, so that the above-described problem of thermal ratchet deformation occurs. In addition, as a preventive measure against the thermal ratchet deformation alone, a rear strong cooling type stave cooler or the like has been proposed, but since the cooling capacity is improved by that amount,
At the time of brick wear, there is a problem that supercooling occurs and the furnace condition is adversely affected.

The present invention solves the problems of the low life and the thermal ratchet deformation of the conventional stave cooler as described above, without improving the cooling capacity more than necessary and changing the structure such as the thickness of the stave cooler. It aims to provide a stave cooler that can be solved with little or no effort.

[0010]

In order to achieve the above-mentioned object, a stave cooler according to the present invention is a stave cooler for protecting a furnace shell from heat load in a furnace. System heat resistance,
Manufactured from wear-resistant cast steel, a plurality of dents are formed on the inner surface of the furnace, and these dents are connected by vertical and horizontal slits that open on the inner surface of the furnace. Heat-resistant refractories are inserted into these dents. It is doing.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION There are various types of heat-resistant and wear-resistant cast steel, which can be roughly classified into austenitic, austenitic containing carbide precipitates, austenitic containing ferrite, and ferritic (grey cast iron). (FC) and spheroidal graphite cast iron (FCD).

The present inventors conducted a transient elasticity analysis by a finite element method using a model at the time of brick wear on the inner surface of the furnace based on the properties of the representative steel types. As a result, the austenitic system containing carbonized precipitates Although it is the best for the heat ratchet deformation, it has been found that the heat shock resistance is poor, so that there is a possibility of large chipping and it is inappropriate.

Further, it has been found that the austenite system has the largest thermal ratcheting deformation (approximately three times that of spheroidal graphite cast iron (FCD)) and is inappropriate. On the other hand, it has been found that the thermal ratchet deformation of the austenitic alloy containing ferrite is about 1/20 that of spheroidal graphite cast iron (FCD). In addition, as a result of the heating test using the same material, almost the same evaluation as the above result was obtained.

Therefore, in the stove cooler of the present invention, the stave cooler body is made of an austenitic heat- and wear-resistant cast steel containing ferrite. Then, a plurality of recesses are formed on the inner surface side of the furnace, and a heat insulating refractory is inserted into these recesses.

That is, in the stave cooler of the present invention,
Conventionally, a brick supporting metal which had only two directions in the vertical direction is integrated with the main body of the stave cooler and is also supported in the left and right directions. In the case of such a structure that supports from the top and bottom and from the left and right, the ratio of the metal area inside the furnace increases, and the cooling performance improves. The area ratio of at least 50 to 60% as in the past is secured.

In addition, in the stave cooler of the present invention, the above-mentioned recesses are connected by vertical and horizontal slits which open to the furnace inner surface side. This is to absorb the difference in thermal expansion between the insulated refractory and the stove cooler body inside the furnace and suppress the generation of excessive stress on the insulated refractory and the stave cooler body inside the furnace.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A stave cooler according to the present invention will be described below with reference to one embodiment shown in FIGS. FIG. 1 is a sectional view showing an embodiment of a stave cooler of the present invention, and FIG. 2 is a perspective view of the same.

In FIG. 1 and FIG. 2, reference numeral 11 denotes a stave cooler body, which has a structure cooled by cooling water supplied through a cooling pipe 11a similarly to a conventional stave cooler. This stave cooler body 11 is made of an austenitic heat resistant material containing ferrite.
Made of wear-resistant cast steel.

During the manufacture of the stove cooler of the present invention, when pouring austenitic heat-resistant and wear-resistant cast steel containing ferrite, the pouring temperature is higher than that of conventional spheroidal graphite cast iron (FCD) (about 1500). C), in order to prevent melting of the cooling pipe 11a, as shown in FIG. 1, for example, a double pipe pipe in which an inner pipe 11ab is movably inserted into an outer pipe 11aa whose outer peripheral surface is chrome-plated. Hiring,
About 3 kg of nitrogen gas having an original pressure of 7 kg / cm ² was introduced into the inner pipe 11ab.
It is desirable to supply at least 5 Nm ³ / H (weight flow rate about 1000 kg / H) and cast while cooling. In addition, regarding the shrinkage of the main body after casting, since only the compressive stress remains in the cooling pipe 11a, it does not cause cracking. In addition, austenitic heat resistance containing ferrite,
Annealing after casting is unnecessary for wear-resistant cast steel.

Reference numeral 11b denotes a plurality of recesses provided on the inner side of the furnace of the stave cooler main body 11, for example, in an area of 50 to 70% of the inner area of the furnace, into which the heat insulating refractory 12 is fitted. I have. In the present embodiment, as described above, when casting an austenitic heat-resistant and wear-resistant cast steel containing ferrite, in order to prevent an accident in which the heat-insulating refractory 12 and molten steel come into direct contact and to reduce thermal shock, The figure shows that a cushion material 13 made of, for example, glass wool is interposed between the heat insulating refractory 12 and the recess 11b.

Austenitic heat-resistant and abrasion-resistant cast steel containing ferrite has a slightly higher coefficient of linear expansion at higher temperatures than ferrite-based cast steel. And the recess 11b
Inside of the stove cooler body 11 surrounding the
A difference in thermal expansion occurs between the “ribs” 11c.

Therefore, in the present invention, a slit 11d of 3 to 5 mm opening on the inner side of the furnace is formed in the rib 11c around the recess 11b, for example, at a pitch of 300 mm in the horizontal direction, and at a pitch of 300 mm in the vertical direction. One dent 11b is provided at one ratio, and a plurality of dents 11b are
It is connected by. Note that the depth of the slit 11d is substantially equal to the depth of the recess 11b.

Further, as shown in FIG. 2, a stop hole 11e having a diameter of about 10 mm is provided at the back end of the slit 11d to prevent the crack from developing due to stress concentration at the back end of the slit 11d. Is more effective. These slits 11d and stop holes 11e
It is desirable to plug the mortar with cushioning mortar or the like so that foreign matter in the furnace does not enter.

The rib 11c has a thickness of 30-40 mm on the inner side of the furnace.
As shown in FIG. 1, it is desirable to provide a reverse taper of about 10/100 to prevent the insulating refractory 12 from falling off.

[0025]

As described above, in the stave cooler of the present invention, the stave cooler body is made of an austenitic heat-resistant and wear-resistant cast steel containing ferrite, and a plurality of recesses are formed on the inner surface side of the furnace. At the same time, these recesses are connected by vertical and horizontal slits that open to the inner surface of the furnace, and insulated refractories are inserted into these recesses. In addition, the service life can be extended, and even if the adiabatic refractory falls off, the thermal ratchet deformation is small, and the stress acting on the cooling pipe can be reduced. Further, since the thickness is almost the same as that of the conventional stove cooler, even if the partial replacement is performed, there is no step in the furnace, and the profile in the furnace does not deteriorate. Further, since the cooling capacity is not strong, the furnace condition does not deteriorate due to supercooling.

The place where the stave cooler of the present invention is installed is not limited to the blast furnace, but can be used as a water-cooled metal for a reaction furnace.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a stave cooler according to the present invention.

FIG. 2 is a perspective view showing an embodiment of a stave cooler according to the present invention.

FIG. 3 is an explanatory view of a stave cooler described in JP-A-59-7882.

FIG. 4 is an explanatory view of a stave cooler described in JP-A-63-35708.

FIG. 5 is an explanatory view of a stave cooler described in Japanese Utility Model Laid-Open No. 63-30333.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Stave cooler main body 11b Depression 11c Rib 11d Slit 12 Insulated refractory

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C21B 7/10 F27D 1/12

Claims (1)

(57) [Claims] 1. A stave cooler for protecting a furnace shell from heat load in a furnace, wherein a stave cooler body is made of an austenitic heat-resistant and wear-resistant cast steel containing ferrite, and a plurality of stave coolers are provided on the furnace inner surface side. A stove cooler characterized by forming recesses, connecting the recesses with vertical and horizontal slits opening toward the furnace inner side, and inserting a refractory material into these recesses.