JPH0914858A - Repairing structure of furnace shell and repairing method therefor - Google Patents

Abstract

PURPOSE: To be able to suppress the stress corrosion cracking progress by using a support jig as a welding backing metal and spacer, and press injecting and filling thermal conductive heat resistant material in a gap formed between a repairing plate and a shell. CONSTITUTION: Fine ring-like lateral support jigs 2, 3 are welded fixedly to the upper and lower parts of the position to be repaired of a furnace shell. In order to repair, the lower ends of repairing plates 4, 4' circumferentially divided into a plurality are superposed on the lower jig 3, and welded fixedly. A predetermined gap is formed between the plates 4, 4' mounted via the jigs 3, 5 and a shell 1. That is, the lower ends of the plates 4, 4' and the side edges 4a, 4'b are welded fixedly to the jigs 3, 5. Thereafter, thermal conductive refractory is press injected from filler press injection inlets provided, in place, at the plates 4, 4'. Thus, the filler is press injected in the gap to discharge the air between the plate 4 and the shell 1 from the gap between the upper parts of the plates 4, 4' and the upper jig 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repair (including reinforcement) structure for protecting a furnace shell of a vertical furnace such as a blast furnace or a hot blast stove, and a repair method.

[0002]

2. Description of the Related Art Generally, when repairing a furnace shell of a blast furnace, a hot blast stove, etc., when the repair range such as cracks is small,
This is dealt with mainly by preventing leakage of internal pressure by installing a caul plate slightly larger than the crack repair portion. On the other hand, when the repair range becomes large, a gap is likely to be formed between the existing furnace body skin and the repair plate, so such a space is formed in advance, and by filling this space,
Measures are taken to reduce the temperature difference between the existing steel skin and the repaired steel skin, thereby preventing cracks (recurrence) of the steel skin due to thermal stress.

By the way, the cracks that occur in the iron shell of a hot-blast stove are mainly caused by the progress of stress corrosion cracking on the inner surface of the iron shell and the penetration to the outer surface. Since the repair is done only from the outside, there was a tendency that the repair could not be completed and the recurrence was likely to occur. Moreover, in such a case, generally, stress corrosion cracking also occurs in other portions. Moreover, since the repair plate is fixed by welding directly to the furnace body iron shell, a large thermal stress is generated at that portion, which promotes stress corrosion cracking on the inner surface. Therefore, in repairing the furnace shell, it is an important measure to reduce the thermal stress.

On the other hand, conventionally, as a method for reducing the thermal stress at the time of repairing the iron shell of the furnace body, as disclosed in Japanese Utility Model Laid-Open No. 165595/1983, the peripheral edge of the repair plate is bent toward the welding side. A method of forming a gap with the iron skin and filling the castable in the gap,
As disclosed in Japanese Patent No. 4526, there is known a method in which a rib and a tab ring iron plate are used to form a double-layered structure of iron skin, and molten tin is poured into the gap.

[0005]

By the way, the problem that the prior art has in common is that it is not possible to completely prevent recurrence of cracks due to thermal stress inevitably generated during repair. For example, in order to repair a wide area such as a straight body part of a hot-blast stove, a repair plate is put on the repair part and then fixed by welding. At this time, the furnace shell and the repair plate are Due to the gap between the two, it acts as a heat-insulating layer, which significantly increases the temperature of the shell. Even if the iron shell temperature rises in this way temporarily, if the welding and fixing of the repair plate is completed and the castable is filled in the gap, the temperature of the iron shell decreases due to this action. A tensile stress is generated due to the temperature difference, and as a result, a new stress corrosion cracking is induced in the iron shell.

Further, in the above-mentioned conventional technique, since the repair plate is directly welded to the existing iron shell, thermal stress acts on the welded portion and sometimes promotes cracking. there were.

An object of the present invention is to solve the above-mentioned problems that the prior art has, and in particular, repair of the furnace body iron shell does not lead to an increase in the iron shell temperature, and even cracks due to thermal stress. The purpose of this is to establish and propose a technology for preventing the occurrence of the above-mentioned problem and achieving the purpose of the repair, thereby reliably improving the life of the furnace body and reliably producing the result of the repair.

[0008]

As a means for achieving the above-mentioned object, the present invention provides two kinds of support fittings, that is, a pair of support fittings, to the iron shell in advance for attaching (welding and fixing) a repair plate. The ring-shaped horizontal support metal fittings and the strip-shaped vertical support metal fittings attached in the vertical direction are fixed, and the gaps for filling the refractory and the upper and lower end parts of the repair plate and the side edge parts are welded and fixed through these metal fittings. It is a technique to do, the feature is that the vertical support fitting is used as a backing metal and spacer at the time of welding, the repair plate is assembled into a cylindrical shape, and after welding and fixing with the lower horizontal support fitting, The idea is to fill the refractory and weld the upper lateral support fitting and the upper portion of the cylindrical repair plate after the temperature of the iron skin stabilizes.

That is, according to the present invention, in a repair structure for an iron shell having a structure in which the outer peripheral surface of the furnace shell is surrounded by a cylindrical repair plate with a filler, a repair portion of the iron shell is provided. , The upper part of it, and the ring-shaped horizontal support fittings are fixed to the lower part,
A strip-shaped vertical support metal fitting provided so as to bridge between these horizontal support metal fittings is fixed, and the upper and lower end portions of the repair plate whose circumferential direction is divided into a plurality of parts are joined via each of the horizontal support metal fittings. At the same time, the side edges of the repair plate were joined via the vertical support fittings, and a filling material was press-fitted into the gaps formed between the support fittings and the repair plate and the outer peripheral surface of the iron shell. This is a repair structure for the furnace body iron skin.

The present invention also provides a method for repairing the outer peripheral surface of a furnace body skin by surrounding it with a plurality of repair plates with a filler intervening, 1) the upper part of the part to be repaired, A pair of ring-shaped horizontal support fittings are respectively welded and fixed to the lower part, and one or more vertical support fittings are fixed so as to bridge between the upper and lower horizontal support fittings in the vertical direction of the repaired part, 2) , The lower end of each repair plate is welded and fixed on the lower horizontal support fitting, 3) and the seam portion in the circumferential direction of the repair plate is
Using the vertical support metal fitting as an intermediary for the vertical support metal fitting as a backing metal and spacer, the side edges of the repair plate are welded and fixed to each other to form a concentric cylindrical repair plate surrounding the furnace shell. , 4) After that, between the cylindrical repair plate and the outer peripheral surface of the steel shell,
In the gap obtained by interposing the horizontal support metal fittings and the vertical support metal fittings, the filler is press-fitted through the filler pressure inlet provided in the repair plate, and 5) after that, when the temperature of the repair portion becomes stable, A method for repairing a furnace body iron shell is proposed, in which the upper lateral support bracket and the upper end of the repair plate are fixed by welding.

[0011]

According to the present invention, a pair of ring-shaped horizontal support fittings are welded and fixed in advance to the upper and lower portions of a portion requiring repair or reinforcement, and strip-shaped vertical support fittings are also fixed in the vertical direction. By using these metal fittings as a welding backing metal and spacer, the arc of repair is surrounded by a plurality of arc-shaped repair plates. The load is reduced and crack recurrence can be prevented.

In addition, in the present invention, after such welding and fixing, a good heat conductive refractory material is press-fitted into the gap formed between the repair plate and the existing iron skin, and these (existing iron skin and repair plate are filled). After the temperature of) is stabilized, the upper lateral support bracket and the upper end of the repair plate are welded and joined, so new thermal stress does not occur in the steel shell, so it is possible to suppress the development of stress corrosion cracking. Therefore, the life of the furnace shell can be expected to be extended.

[0013]

FIG. 1 shows an embodiment of the present invention when repairing a furnace shell of a hot-blast stove using four cylindrical repair plates. Reference numeral 1 shows a hot-air stove furnace body iron shell, and thin ring-shaped horizontal support fittings 2 and 3 are welded and fixed to the upper and lower portions of the repair portion of the furnace body shell. In repairing, first, the lower ends of the repair plates 4 and 4 ′ whose circumferential direction is divided into a plurality of parts are overlapped and welded and fixed on the lower lateral support fitting 3. That is, repair plates 4, 4
Initially, only the lower end portion of the mounting of the ′ is attached to the lower lateral support fitting 3, and the upper portion is not fixed at this point. The upper end of the repair plate and the upper horizontal support fitting 2 are fixed by welding after the temperature of the iron shell of the repaired part is stabilized. Such a construction method is effective in avoiding the adverse effect of the relative position shift due to the thermal expansion and contraction due to the temperature difference between when the temperature is high and when the temperature is stable, which is observed immediately after mounting the repair plate.

In the illustrated example, these repair plates 4 and 4'are
The circumferential direction is divided into four, but after the lower end portion is fixed by welding, the respective side edges are then joined. This work
Butt the side edge 4a of the repair plate 4 and the side edge 4'b of the repair plate 4'on the vertical support fittings 5 and 5'fixed in the vertical direction between the upper and lower horizontal support fittings 2 and 3. By welding these vertical support fittings 5 and 5'as welding backing metal and spacer,
It is attached so as to surround the entire circumference in the circumferential direction.
Therefore, it is preferable to use those in which the corners are scraped off so that the side edges 4a, 4a 'have a weld groove shape.

FIG. 2 is a vertical cross-sectional view showing a state in which the upper and lower lateral support fittings 2 and 3 and the repair plates 4 and 4'are attached to the outer peripheral surface of the iron shell 1 (only the lower portion is fixed by welding).

As described above, a constant gap 6 is formed between the iron shell 1 and the repair plates 4 and 4'which are attached via the support fittings 3 and 5. That is, the lower ends of the repair plates 4 and 4'and the side edges 4a and 4'b are welded and fixed to the support fittings 3 and 5. After that, a refractory material having a good thermal conductivity is press-fitted through the filler material press-in port 7 provided at an appropriate position on the repair plates 4, 4 '. In this way, by pressing the filler 8 into the gap 6,
The air between the repair plate 4 and the furnace body shell 1 is discharged from the gap between the repair plate 4 and the upper lateral support fitting 2 above the repair plate 4, 4 '. In addition,
The filling is performed until the filling material 8 leaks from the gap, and the filling work such as castable is stopped at this point.

A filling material 8 such as castable is provided in the gap 6.
By press-fitting and filling, the furnace shell 1 and the repair plate 4,
The temperature of 4'decreases gradually. Then, when the hardening of the filler 8 is completed, the iron skin temperature also becomes stable,
The displacement of the relative position of both is also eliminated. This means that the temperature stability is detected by a thermometer (not shown) that is installed in advance, and after the temperature is firmly stabilized, the final welded portion between the upper lateral support fitting 2 and the repair plates 4 and 4'is welded and joined. . When such a construction method is adopted, the displacement of the relative position due to the temperature change during construction can be absorbed, new thermal stress caused by the repair is not generated, and eventually the development of stress corrosion cracking can be prevented.

In the above-mentioned embodiments, the case where the press-fitting operation of the filler 8 is completed at once is explained, but the present invention is not limited to this method, and the repair plates 4, 4 '.
A plurality of stages of filling material inlets 7 are provided in the height direction of the filling material 8
The method may be such that the space is filled several times so that the space due to curing shrinkage or the like is minimized.

FIG. 3 is a cross-sectional view showing a state where the repair is completed. In particular, this figure shows the details of the welded portion between the repair plates 4 and 4'and the vertical support fitting 5, and shows the state in which a groove is provided on the welded backing metal / spacer and welded. There is. Therefore, the vertical support fitting 5 functions as a backing metal during welding and also functions as a spacer for securing a space when the filler 8 is press-filled.

According to the present invention, the existing steel shell 1 and the vertical support fitting 5 are not fixed by welding, but fixed by a certain degree of positioning, so that relative displacement due to temperature change can be absorbed and thermal stress can be absorbed. Effectively prevent the occurrence of.

[0021]

As described above, according to the present invention,
First, the lower end of the repair plate and its side edge are welded, and then a refractory material with good thermal conductivity is press-fitted into the gap formed between the repair plate and the furnace shell, and the temperature of the repair point is increased. Since the upper edge of the repair plate is welded after the temperature has stabilized, it is possible to effectively prevent the development of stress corrosion cracking due to thermal stress during repair,
The life of the furnace body can be extended.

[Brief description of the drawings]

FIG. 1 is a perspective view showing how to attach a repair plate according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the condition after the repair plate is attached.

FIG. 3 is a cross-sectional view showing a state after completion of repair.

[Explanation of symbols]

 1 Furnace iron shell 2 Upper horizontal support bracket 3 Lower horizontal support bracket 4,4 'Repair plate 5, 5'Vertical support bracket 6 Gap 7 Filler pressure inlet 8 Filler

Claims (2)

[Claims] 1. A repair structure for an iron shell according to a structure in which an outer peripheral surface of the furnace shell is surrounded by a cylindrical repair plate with a filling material interposed between the repair portion and the upper portion of the furnace shell. Then, the ring-shaped horizontal support metal fittings are fixed to the lower part, and the strip-shaped vertical support metal fittings provided so as to bridge between these horizontal support metal fittings are fixed. While joining the upper and lower ends of the split repair plate, and joining each side edge of the repair plate through the vertical support metal,
A repair structure for a furnace body iron shell, wherein a filler is press-fitted into a gap formed between each of the support fittings and the repair plate and the outer circumferential surface of the iron shell. 2. A method of repairing an outer peripheral surface of a furnace body iron shell by surrounding it with a plurality of repair plates with a filler intervening, 1) a pair of upper and lower parts to be repaired. Each of the ring-shaped horizontal support metal fittings is welded and fixed, and at least one vertical support metal fitting is fixed in the vertical direction of the repair portion so as to bridge between the upper and lower horizontal support metal fittings, 2) and then the lower horizontal support metal fitting. Weld the lower end of each repair plate onto the support metal fittings, and 3) and at the seam in the circumferential direction of the repair plate,
Using the vertical support metal fitting as an intermediary for the vertical support metal fitting as a backing metal and spacer, the side edges of the repair plate are welded and fixed to each other to form a concentric cylindrical repair plate surrounding the furnace shell. , 4) After that, between the cylindrical repair plate and the outer peripheral surface of the steel shell,
In the gap obtained by interposing the horizontal support metal fittings and the vertical support metal fittings, the filler is press-fitted through the filler pressure inlet provided in the repair plate, and 5) after that, when the temperature of the repair portion becomes stable, A method for repairing a furnace shell, comprising welding and fixing the upper lateral support bracket and the upper end of the repair plate.