JP2012012691A - Method for replacing hot-air pipe for supplying hot air to blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for replacing a hot-air pipe for supplying hot air to a blast furnace that enables a hot air pipe for supplying hot air to a blast furnace to be replaced properly in a short period of time, and enables the replacement to be made in a period (approximately four days) when supply of hot air is stopped during normal operation of the blast furnace.SOLUTION: The method for replacing a hot-air pipe for supplying hot air to a blast furnace includes: a new hot-air pipe preparation step in which a new hot-air pipe 23 is prepared beside an existing hot-air pipe 13A that needs replacing; an existing hot-air pipe cutting and removing step in which the existing hot-air pipe 13A that needs replacing is cut by a wire saw and removed after the supply of hot air to the blast furnace is stopped; a cut surface care and cleaning step in which the cut surface of the remaining existing hot-air pipe 13B undergoes care and cleaning work while radiation heat by the residual heat of the remaining existing hot-air pipe 13B is blocked by a balloon-type heat blocking device; and a new hot-air pipe moving and connecting step in which the new hot-air pipe 23 is installed at the existing hot-air pipe 13A that has been cut and removed, by a horizontal movement, and the new hot-air pipe 23 is connected to the remaining existing hot-air pipe 13B by welding.

Description

  The present invention relates to a method for replacing a hot air tube (hot air tube for blowing blast furnace hot air) for blowing hot air from a hot air furnace to a blast furnace.

  The hot air of 1000 to 1200 ° C. fed to the blast furnace in the blast furnace operation is usually blown into the blast furnace by heat exchange of air in the hot blast furnace. At that time, a blast furnace hot air blowing hot air tube (hereinafter also simply referred to as a hot air tube) that blows hot air from a hot air furnace to a blast furnace is a steel iron with a diameter of about 3 m that is lined with refractory bricks to withstand high temperatures. Composed of skin. The pressure of blowing is usually a high pressure of 0.4 to 0.5 MPa.

  For this reason, the hot air pipe is cracked in the steel iron skin due to stress corrosion cracking, and there is a risk of blasting in a severe case.

  For this reason, until now, when cracks have occurred in the steel iron skin, the cracks have been repaired by welding or padding. (Patent Document 1), and taking measures to replace the hot air tube in accordance with the blast furnace renovation.

JP 10-46223 A JP 2007-314821 A

  As described above, the hot blast tube for blowing blast furnace hot air is a device for blowing hot air into the blast furnace, and the breakage immediately stops the operation of the blast furnace. For this reason, when a crack occurs in the steel iron skin, it is dealt with by repair work such as welding repair or double pipe structure construction, but in some cases there is a risk that the crack will develop further and become a large crack. If the number of large cracks increases, the strength of the entire hot air tube decreases, and the hot air tube needs to be replaced.

  Incidentally, in welding repair, welding is performed at a high temperature during operation, so it is difficult to guarantee the performance of welding, and cracks often occur again. In addition, because the double pipe structure cannot prevent hot air from coming into contact with the inner surface of the iron skin, there is a risk that cracks will occur after about 10 years in the double pipe structure. Replacement of the entire hot air tube is required.

  However, replacement of hot blast tubes for blowing blast furnace hot air has been abandoned during normal operation because it took a long time for replacement and it was difficult to ensure the reliability of refractory bricks after replacement. It was mostly carried out according to the construction.

  That is, the resting time in normal operation of the blast furnace is generally about 100 hours (about 4 days), but since the inside of the hot air tube before the resting is 1000 to 1200 ° C., the temperature at which the replacement work can be performed. It took more than a week to cool down to the normal temperature, and it was difficult to replace it during the period when the normal operation could be stopped.

  For this reason, there was a problem that there was a large risk of a major accident such as hot-air tube blasting before the blast furnace renovation work, and in some cases, the blast furnace renovation had to be accelerated.

  The present invention has been made in view of the circumstances as described above, and can replace the blast furnace hot air blowing hot air tube appropriately in a short time, and can perform a quiescent period (about 4 days) during normal operation of the blast furnace. ) Provides a hot air tube replacement method for blowing blast furnace hot air.

  In order to solve the above problems, the present invention has the following features.

[1] A method for replacing a hot air tube for blowing hot air from a hot air furnace to a blast furnace,
A new hot air pipe preparation process in which a new hot air pipe is prepared next to an existing hot air pipe at a location where replacement is necessary in advance.
After the blast furnace is rested, the existing hot air pipe cutting and removing step of removing the existing hot air pipe at the location where replacement is necessary by cutting the iron skin and the refractory brick with a wire saw while being integrated,
Using a balloon-type heat shield that constantly supplies air to the inside of the balloon to shut off the radiant heat, while cutting off the radiant heat due to the residual heat of the remaining existing hot air pipe, the cut surface of the remaining existing hot air pipe A cut surface maintenance process for performing maintenance work of the iron skin and refractory bricks,
A new hot air pipe is installed at the position of the existing hot air pipe that has been cut and removed, and the new hot air pipe is connected by welding to the existing hot air pipe. A hot-air tube replacement method for blowing blast furnace hot air.

  According to the present invention, it is possible to replace the hot air tube in a rest period of about 4 days during normal operation of the blast furnace without waiting for the blast furnace repair work. In addition, damage to the refractory bricks inside the hot air tube is minimal, and the reliability of the hot air tube after replacement can be ensured.

  As a result, operation with the risk of serious accidents such as hot-air tube blasting can be avoided. In addition, the cause of the blast furnace refurbishment can be eliminated and the life of the blast furnace will be extended.

It is an elevation view showing one embodiment of the present invention. It is a top view which shows one Embodiment of this invention. It is a figure which shows a wire saw. It is a figure which shows the state which has cut | disconnected the existing hot air pipe with the wire saw. It is a figure which shows the state which water-cools a wire saw. It is a figure which shows a balloon type heat shield.

  An embodiment of the present invention will be described with reference to the drawings.

  1 and 2 show an embodiment of the present invention. FIG. 1 is an elevation view and FIG. 2 is a plan view.

  1 and 2, the hot stove 10 includes a combustion chamber 11 and a heat storage chamber 12, and heat is exchanged between the combustion chamber 11 and the heat storage chamber 12 to form hot air, and the hot air is installed on the deck 14. The hot air tube 13 is used to blow air to the blast furnace.

  In this embodiment, when the hot air tube 13 is replaced, the following steps (S1) to (S4) are performed.

(S1) New hot air tube preparation process A new overhanging deck 24 is newly installed at the same height as the immediate deck 14 of the existing hot air tube 13A at the location where replacement is required, and new hot air is preliminarily placed on the overhanging deck 24. The tube 23 is integrally manufactured in a form in which refractory bricks are also constructed, and drying is completed to prepare.

(S2) Existing hot air pipe cutting and removing step After the blast furnace is rested, the existing hot air pipe 13A at the place where replacement is necessary is cut and removed with a wire saw with the iron skin and refractory bricks integrated. Here, as shown in FIG. 2, cutting is performed at five points C1 to C5.

  Incidentally, as shown in FIG. 3, the wire saw 30 is a cutting tool in which a diamond piece 32 is knitted into an element wire of a steel wire rope 31. Reference numeral 33 in the figure denotes a misalignment stop ring.

  And FIG. 4 shows the state which cut | disconnected the hot air pipe 13 in the integrated state of an iron skin and a refractory brick using this wire saw 30. FIG. In the figure, 34 is a pulley.

  In this way, when the hot air tube 13 is cut in an integrated state of the iron skin and the refractory brick using the wire saw 30, it can be cut in about 4 hours, and the cut surface of the iron skin and the refractory brick are cut. A good cut surface with no unevenness is secured on both surfaces.

  The wire saw 30 becomes hot due to the residual heat of the hot air tube 13 and the heat generated in the cutting process, but the wire saw 30 is continuously cut by water cooling with a water cooling device 36 as shown in FIG. Is possible. Water cooling of the wire saw 30 is sprayed in the form of a mist with a spray nozzle, whereby the cooling water is almost evaporated and there is no adverse effect on the refractory bricks. Here, reference numeral 35 in the figure denotes a wire drive machine that automatically applies a predetermined tension to the wire saw 30 while traveling on its own.

  Then, the cut existing hot air tube 13A is lowered from the deck 14 to the ground and removed.

(S3) Cut surface care process The iron skin and firebrick maintenance work of the cut surface of the existing hot-air pipe 13B which remains are performed. At that time, the radiant heat due to the high temperature residual heat of the existing hot air pipe 13B (especially refractory bricks) that remains is blocked by a balloon-type heat shield device, and the temperature is maintained at a high level by maintaining the temperature. Enable work.

  Here, as shown in FIG. 6, the balloon-type heat shield device 40 is a heat shield device that always supplies air to the inside of the balloon 41 through the air supply pipe 43 and the balloon support frame 42 to block radiant heat. is there.

  By using this balloon-type heat shield device 40, the radiant heat due to the high-temperature residual heat of the remaining existing hot air pipe 13B (particularly, refractory brick) can be completely blocked. Further, the balloon 41 itself is not damaged.

  Incidentally, as a method for shutting down the hot air ducts during repair, Patent Document 2 proposes a method in which a steel net is put into the ducts and draft air is generated in the hot air ducts. The refractory bricks of the entire pipe are cooled in a draft style, and there are problems that the refractory bricks are damaged at the time of re-starting and that the steel net is not easily handled.

  On the other hand, since this balloon type heat shield 40 is made of cloth, it can be handled easily and does not require a draft wind, so there is no problem of refractory bricks being damaged by the draft wind.

(S4) New hot air pipe moving and connecting step A new hot air pipe 23 is horizontally moved with a winch or the like at the position of the existing hot air pipe 13A cut and removed, and the new hot air pipe 23 and the existing hot air pipe remaining. 13B is welded.

  Thus, in this embodiment, without waiting for blast furnace renovation work, the existing hot air pipe 13A at the place where the replacement is required is performed in a rest period of about 4 days during normal operation of the blast furnace. Can do. Further, damage to the refractory bricks inside the remaining hot air tube 13B is extremely slight, and the reliability of the hot air tube 13 after replacement (remaining hot air tube 13B, new hot air tube 23) can be ensured.

  As a result, operation with the risk of serious accidents such as hot-air tube blasting can be avoided. In addition, the cause of the blast furnace refurbishment can be eliminated, leading to a prolonged blast furnace life.

DESCRIPTION OF SYMBOLS 10 Hot blast furnace 11 Combustion chamber 12 Thermal storage chamber 13 Hot blast tube 13A Hot blast tube 13B which needed replacement | exchange The remaining hot blast tube 14 Deck 23 New hot blast tube 24 Overhang deck 30 Wire saw 31 Steel wire rope 32 Diamond piece 33 Slip prevention ring 34 Pulley 35 Wire drive machine 36 Water cooling device 40 Balloon type heat shield device 41 Balloon 42 Balloon support frame 43 Air supply pipe

Claims (1)

A hot air tube replacement method for blowing hot air from a hot air furnace to a blast furnace,
A new hot air pipe preparation process in which a new hot air pipe is prepared next to an existing hot air pipe at a location where replacement is necessary in advance.
After the blast furnace is rested, the existing hot air pipe cutting and removing step of removing the existing hot air pipe at the location where replacement is necessary by cutting the iron skin and the refractory brick with a wire saw while being integrated,
Using a balloon-type heat shield that constantly supplies air to the inside of the balloon to shut off the radiant heat, while cutting off the radiant heat due to the residual heat of the remaining existing hot air pipe, the cut surface of the remaining existing hot air pipe A cut surface maintenance process for performing maintenance work of the iron skin and refractory bricks,
A new hot air pipe is installed at the position of the existing hot air pipe that has been cut and removed, and the new hot air pipe is connected by welding to the existing hot air pipe. A hot-air tube replacement method for blowing blast furnace hot air.

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