JPH0551615A - Method for connecting hot air pipe for blast furnace - Google Patents

Abstract

PURPOSE:To prevent the pitting by the corrosion of the juncture of hot air pipes for supplying hot air from a hot stove to a blast furnace and the cracking of bricks. CONSTITUTION:The hot air pipes 1 and 1' of the juncture 2 are butted against each other by providing a spacing S corresponding to at least the allowance for thermal expansion in place of connecting the hot air pipes 1 lined with bricks via an expansion joint interposed in the mid-way thereof. A connecting pipe 5 is fitted to the outer periphery of the hot air pipe juncture 2 including the spacing S. This connecting pipe 5 is previously welded and fixed to the one hot air pipe 1' and the other hot air pipe 1 is welded and fixed after the thermal expansion of the hot air pipes by the hot air supply, by that, the connection ends. Since the expansion joint is not used, corrosive drains do not accumulate in the juncture and, therefore, the pitting does not arise any more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a hot-blast tube for a blast furnace, which is lined with a refractory for supplying hot air from the hot-blast furnace to the blast furnace.

[0002]

2. Description of the Related Art Generally, a hot air tube for supplying hot air from a hot air stove to a blast furnace is lined with bricks so as to have heat resistance.
When the operation of the blast furnace is started after the construction or repair of the blast furnace, the temperature of the hot air tube rises to 70 ° C to 100 ° C as the temperature of the lining brick rises in order to pass hot air, and the hot air tube expands thermally. For this reason, expansion joints are provided at required points in order to absorb the thermal expansion of the hot air tube.

Various improvements have been made in the past regarding expansion joints provided in hot-air tubes. For example, in bellows expansion joints, small holes were formed in order to sensitively absorb the reaction force against the blast reaction force. A partition wall and an expandable joint are provided, and hot air in the hot air tube is ejected from a small hole through a pressure guiding tube (refer to Japanese Patent Laid-Open No. 53-109804). It is moved (see Japanese Patent Laid-Open No. 53-115606), an end expansion tube and a pressure equalizing tube are provided (see Japanese Patent Laid-Open No. 52-27002) to prevent deformation due to thermal expansion, or by internal pressure extension. To prevent deformation, fix the lower end of the vertical tube to the hot stove stand,
It is disclosed that a lower horizontal pipe is extended to both sides of the vertical pipe, and expansion joints are provided in the lower horizontal pipe (see Japanese Utility Model Publication No. 49-147303).

[0004]

As described above, the most general structure of expansion joints is the bellows type. However, during operation of the blast furnace, corrosive drainage is generated in the hot air tube, and the drainage accumulates on the bellows of the expansion joint. In this way, if the expansion joint portion has a groove-shaped structure portion such as a bellows, drainage in the hot-air tube accumulates there, causing perforation due to corrosion. Moreover, since the expansion joint expands and contracts in a uniaxial direction by changing the pressure in the hot-air tube, the bricks inside fluctuate, which also causes cracks in the bricks.

Normally, a device for draining the drainage accumulated in the groove-shaped structure of the bellows is provided, but the device is used for a long period (5-6).
Year), the bellows are corroded, holes are made, and repair is required. If it is operated for a longer period, it will be difficult to repair and it will be unusable. However, it is difficult to solve the problem that the bellows is corroded by the corrosive drain in the expansion joint disclosed in the above publication. Therefore, the structural weak point of the hot-air tube provided with the expansion joint as described above is the expansion joint. It will be in itself.

It is an object of the present invention to solve these problems and to provide a hot air tube connecting method which has a long life and does not require repair.

[0007]

Means for Solving the Problems The present invention for achieving the above-mentioned object is achieved through an expansion joint for absorbing thermal expansion in the middle of a blast furnace hot air tube lined with bricks for supplying hot air from the hot air furnace to the blast furnace. Instead of connecting, the hot air pipes of the connection portion are butted against each other with a gap corresponding to at least the thermal expansion margin, and the connection pipe is fitted to the outer periphery of the hot air pipe connection portion including the gap, and this connection is made. A tube is welded and fixed to one hot air tube, and the other hot air tube is connected by welding and fixing after the thermal expansion of the hot air tube through the lining bricks by hot air supply and by welding. Is the way.

[0008]

According to the present invention, since the blast furnace hot air tube is connected by welding through the connecting tube instead of connecting through the expansion joint that absorbs thermal expansion in the way as described above,
Since cracks of the refractory and corrosive drain do not concentrate on the connection portion, there is no trouble such as perforation due to corrosion, and repair is unnecessary.

The method according to the present invention can be applied only when the refractory in the hot air tube is dried for 7 to 10 days when the hot air stove of the blast furnace is constructed or refurbished and the operation is started. The temperature of the shell of the hot-air tube rises from the atmospheric temperature to 50-80 ℃ during this period. During the operation of the blast furnace, hot air is passed through the hot blast stove (10 to 15
This is because the temperature changes of both hot-air tubes and refractories are small.
That is, during the operation period, the hot air tube does not generate thermal stress to the extent that an expansion joint is required even if there is a break in air, and the present invention provides structural stability.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, reference numeral 4 denotes a hot blast stove, which constantly sends hot blast into the hot blast tube 1 through the hot blast valve 3 from at least one hot blast stove to supply it to the blast furnace. A connecting portion 2 according to the present invention is provided at a required position in the middle of the hot air tube 1.

As shown in FIG. 1, the connecting portion 2 of the hot air tube 1 abuts the hot air tube 1 and the hot air tube 1'to be connected with each other with a gap S corresponding to at least a thermal expansion margin. At this time, the connecting pipe 5 is fitted around the outer circumference of either the hot air pipe 1 or 1 '. After the hot air pipes 1 and 1 ′ are butted against each other, the connecting pipe 5 is moved to the connecting portion 2 including the gap S. Then, first, the connecting pipe 5 is welded and fixed to one hot air pipe 1'along the pre-temperature welding line 6.

Next, hot air is blown into the hot air tubes 1, 1'to dry and heat the lining brick (not shown),
In a state in which 1'has reached a temperature of 70 to 100 ° C., which is a level equivalent to that in normal operation, and has been thermally expanded, the other hot air tube 1 and the welding line 7 are welded and fixed together to complete the connection. Since the hot air tube adopting the present invention has started its operation, there is no repair of the hot air tube or the brick due to a trouble due to thermal strain, and stable operation is possible for a long period of time.

[0013]

As described above, according to the present invention, the structural weakness of the hot-air tube is eliminated and the need for repairs due to various troubles is eliminated, so that not only the operation of the blast furnace is stabilized but also the blast furnace idle time is reduced. Can be achieved.

[Brief description of drawings]

FIG. 1 is a side view showing a partial cross section of a connecting portion of a hot air tube for a blast furnace according to the present invention.

FIG. 2 is a plan view showing the arrangement of connection parts of the hot air tube according to the present invention.

[Explanation of symbols]

 1 Hot-air pipe 2 Connection part 3 Hot-air valve 4 Hot-air stove 5 Connection pipe 6 Welding line before temperature rise 7 Welding line after temperature rise

Claims (1)

[Claims] 1. Instead of connecting a blast furnace hot-air tube lined with bricks for supplying hot air from the hot-air stove to the blast furnace via an expansion joint that absorbs thermal expansion, at least the hot-air tube comrades of the connecting portion are heated. While abutting with a gap corresponding to the expansion allowance, a connecting pipe is fitted to the outer periphery of the hot air pipe connecting portion including the gap, and this connecting pipe is welded and fixed to one hot air pipe, and the other A method for connecting a hot-air tube for a blast furnace, wherein the hot-air tube is welded and fixed after the thermal expansion of the hot-air tube through a brick lined with hot air to be connected.