JP2932985B2 - 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 stave cooler for protecting, for example, a steel shell of a blast furnace or a reaction furnace from a thermal 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 The material of the stave cooler was originally made of gray cast iron (FC).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.

FIG. 5 shows a Japanese Patent Application Laid-Open No. 63-35708.
In Japanese Utility Model Application Laid-Open No. 63-30333 shown in FIG. 6, molded refractories 3 are laminated on the furnace inner surface side of the stove 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,
The mechanical strength is small, and when used in a high heat load region, 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 effort.

[0010]

In order to achieve the above-mentioned object, a stave cooler of the present invention is a stave cooler for protecting a furnace shell from heat load in a furnace. austenitic containing ferrite, the support ribs fabricated with a wear resistant cast steel, see insert casting with thermal insulation refractory held in fitted shape by the supporting rib and the cushion material between the stave cooler body and the supporting rib It is interposed.

[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, the stave cooler of the present invention includes a support rib made of an austenitic heat-resistant and wear-resistant cast steel containing ferrite, together with a heat-insulating refractory fitted into the support rib, on the furnace inner surface side of the stave cooler body. , And a cast-in configuration. That is, in the stave cooler of the present invention, since the supporting ribs are made of austenitic heat-resistant and wear-resistant cast steel containing ferrite, the period until the adiabatic refractory falls off is lengthened, and the life of the stave cooler is extended.

[0015] In addition, since the interposed cushion material between the stave cooler body and the support ribs, the years of use, the support ribs are worn from the front, also as a heat-insulating refractory falls off, to stave cooler body The heat load does not increase. Further , the difference in thermal expansion between the stave cooler main body and the support rib can be absorbed. According to experiments by the present inventors, it has been confirmed that the area of the support rib is desirably 30 to 50% of the furnace inner area of the stave cooler body.

[0016]

1 to 3 show a stave cooler according to the present invention.
A description will be given based on one embodiment shown in FIG. 1A and 1B are views showing an embodiment of a stave cooler of the present invention, wherein FIG. 1A is a perspective view as viewed from the furnace inner surface side, FIG. In the drawing showing one embodiment of the cooler,
FIG. 3 is a partial cross-sectional view of an embodiment of a stave cooler of the present invention, in which FIG. It is a figure which shows the thing after wear.

In FIG. 1 to FIG. 3, reference numeral 11 denotes a stave cooler body, which is cooled by cooling water supplied through a cooling pipe 11a similarly to a conventional stave cooler. In the present invention, a plurality of support ribs 12 made of an austenitic heat-resistant and wear-resistant cast steel containing ferrite are held by the support ribs 12 on the inner side of the furnace of the stave cooler body 11 in a fitting manner. Together with the insulated refractory 13, it is cast in parallel in the lateral direction. In addition, 15 in FIGS. 1-3 shows a cast-in cast iron.

When the stave cooler of the present invention is manufactured, in order to prevent carburization of the support rib 12, the surface of the support rib 12 to be welded to the stave cooler body 11 is calorized, and the support rib 12 is cast. In order to reduce the residual stress caused by the difference in thermal expansion between the support rib 12 and the stave cooler body 11, the support rib 12 is cast at 500 to 600 ° C.
It is important to preheat to a certain degree. In order to prevent the cooling pipe 11a from being melted at the time of casting, a double pipe pipe, which is movably inserted into an outer pipe whose outer peripheral surface is chrome-plated but is not shown, is adopted, for example,
Take measures such as supplying nitrogen gas into the inner pipe while cooling it and casting.

Since the stave cooler body 11 and the support rib 12 are made of different materials, a difference in thermal expansion occurs between the stave cooler body 11 and the support rib 12 when the stave cooler body 11 and the support rib 12 are used in a blast furnace. Therefore, in order to absorb the difference in thermal expansion, for example, a cushion member 14 is provided between the stave cooler main body 11 and the support rib 12. In this cushion material 14, the support ribs 12 are worn from the front surface due to long-term use, and FIG.
As shown in (b), even if the heat insulating refractory 13 falls off, it also has an effect of preventing the heat load on the stave cooler main body 11 from increasing.

Further, the support ribs 12 are shown in FIGS.
As shown in the figure, a reverse taper of about 10/100 is provided,
It is desirable to prevent the insulating refractory 13 from falling off. Further, in order to strengthen the welding integration between the stave cooler main body 11 and the support rib 12, the back side of the support rib 12 has
Shaft 1 to be inserted into stave cooler main body 11 at predetermined intervals
It is desirable to protrude 2a.

[0021]

As described above, in the stave cooler of the present invention, a support rib made of austenitic heat-resistant and wear-resistant cast steel containing ferrite is provided on the inner side of the furnace of the stave cooler main body. see insert casting with thermal insulation refractory material held in the fitted shape, and, since the interposed cushion material between the stave cooler body and the support ribs, such as by falling off of the heat insulating refractory is prevented as much as possible 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. Also, since the thickness is almost the same as the conventional stave cooler, even if you perform partial replacement,
The furnace profile does not deteriorate. Further, since the cooling capacity is not strong, the furnace condition does not deteriorate due to supercooling.

Incidentally, in the stave cooler of the present invention,
Approximately 3 years until total loss of insulated refractories (about 1 year with conventional stave cooler), approximately 2 years until total loss of support ribs, 3-4 years until breakage of cooling pipe due to thermal ratchet deformation (with conventional stave cooler) Therefore, the life of the stove cooler of the present invention is 8 to 9 years, which is about twice the life of the conventional stave cooler (4 to 5 years). In addition,
The place where the stave cooler of the present invention is installed is not limited to a blast furnace, and can be used as a water-cooled metal component of a reaction furnace.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an embodiment of a stave cooler according to the present invention, wherein (a) is a perspective view seen from the furnace inner surface side, and (b) is a perspective view seen from the steel shell side.

FIG. 2 is a partial perspective view of an embodiment of the stave cooler of the present invention, which is a partial cross-sectional view of a steel shell side.

3A and 3B are partial cross-sectional views of one embodiment of a stave cooler according to the present invention, wherein FIG. 3A is a diagram showing a state before a heat-insulating refractory is worn, and FIG.

FIG. 4 is an explanatory view of a stave cooler described in JP-A-59-7882.

FIG. 5 is an explanatory view of a stave cooler described in JP-A-63-35708.

FIG. 6 is an explanatory view of a stave cooler described in Japanese Utility Model Laid-Open No. 63-30333.

[Explanation of symbols]

 11 Main body of stave cooler 12 Support rib 13

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 63-159197 (JP, U) “Steel Materials Handbook”, 2nd edition, 2nd printing, p. 628-630, edited by The Japan Institute of Metals and The Iron and Steel Institute of Japan, Maruzen Co., Ltd., October 20, 1976 (58) Fields investigated (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 support rib made of an austenitic heat-resistant and wear-resistant cast steel containing ferrite is provided on the inner surface of the stave cooler body. see insert casting with thermal insulation refractory material held in fitted shape by the support ribs, and,
Insert cushion material between stave cooler body and support rib
A stove cooler characterized by being installed .