JP2859691B2 - How to repair cracks in blast furnace steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a method for repairing a steel crack in a blast furnace furnace body. The present invention relates to a method for repairing a blast furnace steel shell which can be performed easily and easily and can extend the life of the furnace body.

<Conventional technology> In general, furnaces that are exposed to high temperatures, such as blast furnaces, take a long time after burning and damage the furnace body cooling devices such as refractory lining bricks, cooling boxes, and staves in the furnace, The blast furnace steel shell may be deformed or cracked. In particular, when seven years or more elapse after burning, most of the refractory bricks in the furnace are eroded, and the cooling device is also damaged or dropped, and when the furnace wall protective body is lost, the heat load on the portion becomes excessive. In addition, hot spots and deformations occur in the blast furnace steel, which may develop into cracks. When such a crack occurs in the furnace, the gas in the furnace is blown out of the furnace, and the operation of the blast furnace must be stopped.

Conventionally, cracks in the blast furnace steel shell have been repaired by drilling stop holes at both ends of the steel shell crack, gouging the cracked area, and then overlay welding or welding a repair steel plate or half-pipe to the cracked area and then repairing them. A rib was attached to the part to reinforce the steel skin or repair. However, in these repairs, cracks re-occurred within a few weeks, and the actual situation was that the repairs were repeated.

In order to improve the method of repairing the blast furnace iron of the prior art, Japanese Patent Publication No. 57-14727 discloses that a crack portion of a blast furnace steel is welded, and then a cooling device is provided on the iron repair part. There has been proposed a method in which a box is attached, and thereafter, a refractory is injected into the inside of the box to form a refractory layer between the cooling device and the blast furnace shell.

<Problems to be Solved by the Invention> Although the prior art proposed in the above-mentioned publication has improved the effect, a refractory layer is formed on the upper surface of the repaired portion having a crack welded, and cooling is performed from the upper portion. Since cooling is performed by the device, the efficiency of cooling the steel skin at the repair section is poor. For this reason, cracks are apt to occur, and if the number of cracks increases, the strength will be reduced. was there.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to propose a method for repairing a blast furnace steel shell with good cooling efficiency.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a method for filling a crack in a blast furnace steel shell with a filler and sealing the same, and then welding a repair steel plate on the steel shell sealing part. To repair the crack in the steel skin, attach a bellows type water-cooled jacket hardware covering the steel skin repaired portion, connect a water supply pipe and a drain pipe to the bellows type water-cooled jacket hardware, and supply water from the water supply pipe. It is configured to cool the steel shell repairing part while maintaining the cooling water pressure in the bellows type water cooling jacket hardware at the same or slightly higher pressure as the gas pressure in the blast furnace, and to drain the water from the drain pipe. This is a method for repairing cracks in the blast furnace steel.

<Operation> As the filler to be filled in the crack portion of the steel shell, it is preferable that the thermal conductivity is equivalent to that of the steel shell. Therefore, for example, an iron putty is filled and sealed, and a repair steel plate is welded to the surface of the steel shell. First, it is recovered by relatively simple work.

Further, a bellows type water-cooling jacket is attached so as to cover the steel skin including the steel skin repairing part, and a hermetically sealed structure is used to directly cool the steel skin repairing part with cooling water. The thickness of the repair steel sheet is suitably 5 to 10 mm in order to enhance the cooling effect. Thus,
The repair suitable for the high heat load of the repair portion where the furnace wall protector in the steel cover 1 becomes thin or no longer exists can be performed.

Usually, since the furnace gas pressure of the blast furnace is a 2.7~3.2kg / cm ^2, or a cooling water pressure in the bellows-type water-cooled jacket hardware equivalent to the furnace pressure, slightly higher pressure or the furnace pressure 0.1 The pressure applied is about kg / cm ² . After repaired by the method of the present invention, if re-cracking occurs in the iron skin repaired part, cooling water will be flooded from the cracked part, but the water pressure in the bellows type water cooling jacket hardware is equal to or slightly higher than the furnace internal pressure. Since the pressure is kept at a low level, no severe flooding occurs in the furnace.

An embodiment of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a blast furnace steel shell, in which the refractory bricks 3 in the blast furnace steel shell 1 fall off, the stave 2 is damaged, and the heat load on the steel shell 1 becomes excessive. However, in the present invention, the cracks 4 of the steel shell 1 are first filled with the filler 6 and sealed, and then the repair steel plate 5 is welded on the steel shell sealed portion to thereby repair the steel shell. The crack 4 is repaired. Next, a bellows-type water-cooled jacket metal fitting 7 is attached by welding so as to cover and cover the steel skin repaired portion to which the repair steel plate 5 is welded, and a water supply pipe 8 and a drainage pipe are attached to the bellows-type water-cooled jacket 7. 9 is connected.

When the repair of the cracked iron shell 4 of the blast furnace is completed as described above, cooling water is supplied from the water supply pipe 8 so that the pressure of the cooling water in the bellows type water-cooled jacket hardware 7 is equal to or slightly lower than the gas pressure in the blast furnace. After the steel repair part is cooled while maintaining the pressure at a high level, it is drained from the drain pipe 9 and guided to the drain gutter 10. In this way, the crack repaired portion of the steel shell 1 is cooled in a water-sealed state by the cooling water directly from the surface of the steel shell to prevent re-cracking of the steel shell 1 accompanied by a high heat load. The inside of the furnace inside 1 is cooled to form an adhered refractory layer, which serves as a protective body for the steel shell 1.

In addition, since the repaired part of the steel shell 1 is directly cooled in a water-sealed state, when the part is re-cracked, the cooling water in the bellows type water-cooled jacket hardware 7 is flooded into the furnace from the re-cracked part. However, in the present invention, by keeping the water pressure of the cooling water equal to or slightly higher than the gas pressure in the furnace, it is possible to prevent a large amount of water from flowing into the furnace from the re-cracked portion, and to prevent accidents due to water intrusion.

In the embodiment of the present invention, the pressure of the cooling water supplied into the bellows type water-cooled jacket metal fitting 7 is adjusted by the pressure adjusting valve 11. At this time, the pressure adjusting valve 11 is provided with a pressure gauge 12 for measuring the furnace pressure. Controlled by the pressure controller 13 based on the pressure signal, the cooling water pressure in the bellows type water-cooled jacket hardware 7 is maintained at a pressure equal to or slightly higher than the gas pressure in the furnace.

When a recrack occurs in the steel shell 1 in the vicinity of the repaired part, the pressure rises in the bellows type water-cooled metal part 7 because the water is directly immersed in the high temperature part in the furnace, but the drain end of the drain pipe 9 is opened. Therefore, the inside of the bellows-type water-cooled hardware 7 is maintained at a normal value without an abnormally high pressure, and the cooling water is drained to the discharge gutter 10, so that flooding is prevented from reaching the inside of the furnace.

In the above embodiment, the pressure gauge 12 and the pressure controller 13
However, since the blast furnace is operated at a constant pressure for each blast furnace, the pressure control valve 11 is set to the blast furnace operating pressure and the bellows type water-cooled jacket metal fitting 7 is controlled. The same effect can be obtained even if cooling water is supplied.

Wherein operating pressure of normal blast furnace is 2.7~3.2kg / cm ^2, or equal to the pressure, it may be supplied to the bellows-type water cooling jacket fittings 7 as pressure plus 0.1 kg / cm ² degree.
When the supply pressure of the cooling water is increased, the water supply to the furnace at the time of re-cracking of the shell increases, and there is a great risk of hindering the operation of the blast furnace.

In addition, as means for judging the inundation in the furnace, it can be detected by a change in the H ₂ concentration in the gas by the furnace top gas analyzer. H ₂ in the top gas detected by the top gas analyzer
Infiltration into the furnace due to the recracking of the steel shell is detected based on the increase in the concentration, and if the pressure of the cooling water supplied to the bellows-type water cooling jacket 7 is reduced based on the detection, the inundation can be prevented.

By the way, in the blast furnace operation, the hydrogen concentration in the blast furnace Bosch section is increased by humidification air blowing or air blowing by adding water at the tuyere, and the blast furnace is used for the ore reduction reaction by hydrogen. Therefore, as long as the hydrogen concentration is within the normal control range, water infiltration into the furnace due to recracking of the steel shell is permitted. At this time, an increase in the H ₂ concentration due to water infiltration can be determined by a top gas analyzer.

Fill the cracks in the iron skin with iron putty, and make the upper surface 6 mm thick
Repaired by welding with a steel plate, and covering the repaired part with a bellows type water-cooled jacket hardware so that the furnace pressure was 3.
Cooling water corresponding to 1 kg / cm ² was supplied at a water supply pressure of 3.2 kg / cm ² so as to be sealed, and the blast furnace steel shell was not re-cracked even after 6 months. Operation could be continued.

<Effects of the Invention> As described above, according to the present invention, a crack in a blast furnace steel shell can be easily recovered by a relatively simple repair work, and the steel shell repair part is directly cooled by cooling water, so that cooling efficiency is improved. Therefore, the occurrence of recracking of the steel shell can be significantly reduced as compared with the conventional case, and the life of the blast furnace body can be extended.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a furnace body when repaired by the method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Iron shell, 2 ... Stave, 3 ... Refractory brick, 4 ... Cracked part, 5 ... Repair steel plate, 6 ... Filler, 7 ... Bellows type water-cooled jacket hardware, 8 ... Water supply pipe , 9 ... drain pipe, 10 ... drain gutter, 11 ... pressure regulating valve, 12 ... pressure gauge, 13 ... pressure controller.

Claims (1)

(57) [Claims] 1. A cracked portion of a blast furnace steel shell is filled with a filler and sealed, and then a steel plate for repair is welded on the sealed portion of the steel shell to repair the cracked portion of the steel shell. A bellows-type water-cooled jacket metal fitting is attached, and a water supply pipe and a drain pipe are connected to the bellows-type water-cooled jacket hardware, and water is supplied from the water supply pipe to reduce the cooling water pressure in the bellows-type water-cooled jacket metal in the blast furnace. A method for repairing a crack in a blast furnace steel shell, comprising cooling the steel shell repair portion while maintaining the pressure equal to or slightly higher than the gas pressure and draining from the drain pipe.