JPH0554526U - Steel skin repair structure for blast furnace - Google Patents

Abstract

(57) [Summary] [Structure] The rib 7 and the doubling iron plate 9 are welded to the repaired part where the cracks along the entire circumference that are generated along the weld line 3 when the iron shell 5 of the hot-blast stove is assembled and constructed are welded. Stop and iron 5
As a double structure having a gap between the doubling iron plate 9 and the doubling iron plate 9, metal tin is poured into the gap to be integrated. [Effect] Iron skin 5 that comes into contact with bricks in the furnace due to metallic tin
Since the temperature difference between the doubling iron plate 9 that is in contact with the outside air is reduced, it is possible to prevent the occurrence of secondary cracks in the iron shell 5 due to the inside and outside temperature differences.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a steel skin repair structure for a hot blast stove for a blast furnace.

[0002]

[Prior Art]

 There is a hot stove as one of the incidental equipment of the blast furnace. The hot blast stove is a heat exchanger that heats the blast air to raise its temperature to a high temperature. As shown in FIG. 4, the heat storage chamber 2 for giving heat to the blast air and the heat storage chamber 4 for heating this heat storage chamber 4 are heated. The combustion chamber 4 and the like. A Gitter brick (not shown) having a honeycomb-shaped gas-permeable hole is stacked in the heat storage chamber 2.

First, during the heat storage period, the gas valve 8 of the fuel gas pipe 6 and the air valve 12 of the combustion air pipe 10 are opened, the fuel gas is taken in from the fuel gas pipe 6, and the combustion air is burned from the combustion air pipe 10. Is taken in and burned in the combustion chamber 4. The gas combusted in the combustion chamber 4 passes through the gas permeation holes from above the heat storage chamber 4 and accumulates the heat amount of the combustion gas in the Gitter brick. At this time, the flue valve 14 is open and the combustion exhaust gas is discharged to the flue 16. When the heating of the heat storage chamber 2 is completed, the gas valve 8, the air valve 12 and the flue valve 14 are closed to end the combustion state.

Next, during the air blowing period, the air blowing butterfly valve 18, the air blowing valve 20, and the hot air valve 22 of the hot air oven are opened, and the air blown from the air blower (not shown) is blown through the air blowing butterfly valve 18 and the air blowing valve 20. It is heated by passing it through the Gitter brick of the heat storage chamber 2 and sent to the blast furnace from the hot air valve 22 through the hot air main 24. The air blow butterfly valve 18 is a valve for adjusting the amount of air blown.

Stress corrosion cracking easily occurs in the hot blast stove, and when cracks occur in the hot blast stove, the internal gas leaks to the outside and is blown at high pressure from the blower especially during the blowing period. As a result, air is ejected from the crack. If the cracks are left as they are, the cracks will progress and become large, making it difficult to maintain the required strength of the hot-air stove, which is a pressure vessel, causing an accident.

Immediate repair is required to stop the progress of cracks. Conventionally, repairing of cracks is generally done by doubling by welding a steel repair plate to the cracked part of the steel skin by welding. .. If the crack range is large, simply repairing the doubling will create an air layer between the steel skin and the doubling steel skin repair plate for thermal insulation, increasing the temperature difference between the steel skin and the doubling steel skin repair plate. However, there is a problem that a large shear stress is generated in the weld repaired part and a secondary crack is generated.

Particularly, during the heat storage period in which the fuel gas and the combustion air are taken into the combustion chamber 4 and burned, and thereby the heat storage chamber 2 is heated, the room temperature in the combustion chamber 4 is close to 1400 ° C. The inner surface of the skin is generally 100 ° C because it is filled with insulating bricks. However, when stress corrosion cracking frequently occurs and local doubling repair has already been performed on small cracks, the air layer as described above is likely to occur. When performing doubling repair on the entire circumference of the furnace body after gouging that can generate large cracks and reduce the amount of welding, a gap of at least about 10 mm is created, and an air layer is formed here. When such a large air layer is formed, the temperature of the steel skin is close to room temperature, and the temperature of the inner surface of the steel skin without air layer is about 300 ° C, which is a serious strength problem.

In order to solve such a problem, the present applicant has proposed a technique of filling a good heat conductive filler between the iron skin and the iron skin repair plate (see Japanese Utility Model Laid-Open No. 58-16559). ). Further, as a method for repairing cracks in the blast furnace skin, Japanese Patent Laid-Open No. 58-187292 discloses that the cracked portion of the blast furnace steel skin is gouged to form a groove having a root interval on the back surface of the steel shell, In Japanese Patent Laid-Open No. 61-144293, after repairing the cracks generated in the iron shell of the pressure vessel by gouging the cracked portion, It is disclosed that a steel repair plate having a specified width and thickness with respect to cracks is used for weld repair.

[0009]

[Problems to be solved by the device]

 Of the above-mentioned conventional techniques, when a good thermal conductive filler is filled between the steel skin and the steel skin repair plate, it is difficult to eliminate the air layer because voids are formed when the filler is dried. .. In addition, even if the technology disclosed in Japanese Patent Laid-Open No. 58-187292 is applied to a hot-blast stove and a groove route is secured after the gouging, and the weld repair is performed using the backing metal and the spacer member, There is a problem that cracks tend to recur from the area and its surroundings. The technique disclosed in JP-A-61-144293 is better than that of the above-mentioned publication because the doubling steel skin repair plate acts as a reinforcing material, but solves the problem of preventing air layer formation. Not a thing.

The present invention has been made in view of the above-mentioned circumstances, and is for a blast furnace capable of repairing cracks generated in the iron skin without forming a gap between the iron skin and the iron skin repair plate. The object is to provide a steel skin repair structure for a hot stove.

[0011]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present inventor investigated a material having a good thermal conductivity and easily poured between the iron skin and the doubling iron plate. As a result, tin, which is a metal material, has a low melting point and a thermal conductivity of almost iron. It was found that they were the same, and the present invention was completed. The gist of the present invention is as follows.

The present invention provides a double structure having a gap between a rib and a tab ring iron plate welded to a repair portion where a crack generated in the iron shell of a blast furnace is welded, and a gap is provided between the rib and the tabling iron plate. However, it is a structure for repairing the skin of a hot blast stove for a blast furnace, which is characterized by pouring metal tin into the gap and integrating it.

[0013]

[Action]

 Since the present invention has the above-mentioned configuration, the repaired portion in contact with the tab ring iron plate and the in-furnace brick that are in contact with the outside air by the metal tin poured between the repair part steel skin and the tab ring iron plate There is almost no temperature difference with the iron shell, and it is possible to prevent the generation of secondary cracks due to the temperature difference between the inside and outside, and to complete the repair of the hot-blast stove iron shell.

[0014]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, cracks due to stress corrosion cracking have occurred all around the weld line 3 formed when welding and integrating the steel shell 4 when constructing the combustion chamber of the hot stove. The case of repairing this will be explained.

The cracked portion of the steel shell 4 along the welding line 3 is first gouged to form a groove for welding. This gouging is carried out to the depth of the crack or more, and in some cases, the crack is completely removed by reaching the back surface of the steel shell 4. Next, if necessary, a back metal is applied to the groove formed on the steel skin 4 by gouging to repair the weld. Subsequently, ribs 7 are attached to the iron skin 5 of the combustion chamber 4 by welding, and then a U-shaped doubling iron plate 9 having a tin inlet 11 and a tin overflow port 13 is welded and fixed to the upper plate. In this manner, the ribs 7 and the doubling iron plate 9 are welded to the entire circumference of the repaired portion of the combustion chamber 4 to form a double structure of the iron shell 4 and the doubling iron plate 9. The rib 7 serves as a reinforcing member for transmitting the load of the body shell 5 of the combustion chamber 4 to the doubling iron plate 9.

When the welding of the rib 7 and the doubling iron plate 9 over the entire circumference is completed, the rib 7 and the doubling iron plate 9 are heated to a temperature of 300 ° C. or more and annealed, and the melting point of tin is 230 ° C. or more. Molten tin is injected from the casting injection port 11, but the rib 7 and the doubling iron plate 9 are heated above the melting point of tin, so that the injection work can be performed without solidification.

When the molten tin is filled in the gap between the doubling iron plate 9 and the iron skin 5, the injection is stopped at the stage when it overflows from the tin overflow port 13, and the tin shrinkage is compensated for while returning to room temperature to solidify the tin. After that, the tin injection port 11 and the tin overflow port 13 are closed using the stopper 15. In this way, when the injection of molten tin is completed in the gaps in the doubling iron plate 9 around the entire circumference, a series of repair work is completed, and when the temperature reaches room temperature, the iron skin 4, the ribs 7, and the doubling iron plate 9 are made of solidified tin. Are integrated through.

In the above-mentioned embodiment, the case of repairing the entire circumference of the combustion chamber 4 has been described. However, as shown in FIG. 3, when repairing a local crack 3'generated in the iron shell 4, the crack is repaired. A rib 7 and a doubling iron plate 9 each having a size suitable for the location can be used to provide a locally repaired steel skin repair structure. Of course, the present invention can be applied to other places such as the heat storage chamber 2 of the hot stove.

[0019]

[Effect of the device]

 As described above, according to the present invention, since there is no temperature difference between the repairing part of the hot stove and the doubling iron plate, there is no secondary crack due to the temperature difference between the inside and outside, and the life of the hot stove is extended. It Moreover, since the inner skin does not get too hot, the strength of the skin can be stably guaranteed.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a plan view showing an arrow AA of FIG.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is an explanatory view showing a schematic overall structure of a hot stove.

[Explanation of symbols]

 1 Iron Skin 2 Heat Storage Chamber 3 Welding Line 4 Combustion Chamber 5 Iron Skin 6 Fuel Gas Pipe 7 Rib 8 Gas Valve 9 Doubling Iron Plate 10 Combustion Air Pipe 11 Tin Inlet 12 Air Valve 13 Tin Overflow Port 14 Flue Valve 15 Plug 16 Flue 18 Blower butterfly valve 20 Blower valve 22 Hot air valve 24 Hot air main

Claims (1)

[Scope of utility model registration request] 1. A double structure having a gap between a rib and a tab ring iron plate is welded to a repair portion where a crack generated in the iron shell of a blast furnace is welded,
A structure for repairing the skin of a hot-blast stove for a blast furnace, which is characterized by pouring metal tin into the gap and integrating it.