JPH01196492A - Exhaust gas duct for melt-reducing furnace - Google Patents

Abstract

PURPOSE:To prevent the exhaust gas and exhaust heat from escaping into the environment and the outside air from being let in when the furnace body is tilted by using a duct whose connection with the mouth of the furnace forms an airtight movable joint and which has at least two or more movable joints at intermediate positions. CONSTITUTION:An exhaust gas duct 7 is designated to compensate the displacement of a furnace body 1 by bending with the mouth 6 of the furnace body 1 connected with the inlet end 8 of the exhaust gas duct 7 in the form of a spherical joint. The connection of the inlet-end duct section 7a and the adjoining second duct section 7b and that of the second duct section 7b and the third duct section 7c on the outlet side also form spherical joints 10, 11. When the furnace body 1 is tiled to pour out the melt, the inlet end 8 of the duct is moved jointly with the titled mouth 6 of the furnace; the inlet-end duct section 7a tilts with shift of the position of the inlet end 8 and the adjoining second duct section 7b tilts as well to compensate the tilt of the inlet-end section 7a. Thus, even when the furnace body 1 is titled, the joint between the mouth 6 of the furnace and the inlet end 8 of the duct maintains airtightness so that the exhaust gas and exhaust heat can be led to the fixed duct section 7c on the outlet side.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention enables tapping of hot water by tilting the furnace body without breaking the airtightness of the joint between the furnace mouth and the exhaust gas duct of the smelting reduction furnace. This invention relates to an exhaust gas duct for a smelting reduction furnace.

[Conventional technology]

In order to reduce iron ore to produce hot metal, methods such as using a blast furnace and melting iron ore raw material reduced in a shaft furnace in an electric furnace have been adopted. However, the blast furnace method requires large-scale equipment. Furthermore, since sintered ore is used as the iron source and coke produced by carbonization of strongly caking coal, additional equipment such as coke oven equipment and sintering equipment is required. Therefore, there is a drawback that not only a large amount of equipment costs but also a large amount of energy and labor are required, leading to a rise in processing costs. On the other hand, the method of reducing iron ore using a shaft furnace requires pre-treatment to pelletize the iron ore, and has the disadvantage that it consumes a large amount of expensive natural gas as a reducing agent and heat source.

As an alternative to such conventional hot metal production techniques, the smelting reduction method is attracting attention. The smelting reduction furnace used in this method was developed for the purpose of producing molten iron alloys using smaller-scale equipment without being restricted by the raw materials used.
There are converters, mixed pig iron furnaces, etc. as disclosed in No.-86794.

In addition, the present inventors have developed a method for tapping hot water without interrupting the blowing operation in this type of smelting reduction furnace, and filed the application as Japanese Patent Application No. 62-235893.

In the smelting reduction furnace disclosed in this prior application, for example, in the case of a mixed iron furnace type, an opening for inserting a lance extending in the circumferential direction is formed in the furnace shell, so that the lance can be inserted into the furnace regardless of the tilting of the furnace body. is maintained.

Since the blowing operation is not interrupted during tapping, not only the operating conditions are stabilized, but also quantitative fluctuations in the exhaust gas and exhaust heat discharged from the smelting reduction furnace can be suppressed. Therefore, there are preliminary reduction furnaces, preheating furnaces, and
This eliminates the need to significantly change the operating conditions of heat recovery boilers, etc.

[Problem to be solved by the invention]

However, when tapping the metal by tilting the furnace body in this manner, it is necessary to separate the furnace opening and the exhaust gas hood.

At this time of separation, exhaust gas and exhaust heat flow out from between the furnace mouth and the exhaust gas hood, which tends to deteriorate the working environment and cause reduction components and heat to dissipate. Alternatively, when outside air is drawn into the exhaust gas hood, the components of the exhaust gas sent to subsequent processes such as the pre-reduction furnace, preheating furnace, and heat recovery boiler change, and the amount of heat decreases.

That is, by simply connecting the furnace body and the exhaust gas hood, it is not possible to fully utilize the advantages of tapping the hot water without interrupting the blowing operation. Furthermore, no specific means has been proposed so far for establishing an airtight connection between the furnace mouth and the exhaust gas hood when the furnace body is tilted.

Therefore, by making the exhaust gas duct multi-jointed, the inlet side of the exhaust gas duct is airtightly connected to the furnace mouth even when the furnace body is tilted, thereby preventing exhaust gas and exhaust heat from flowing out and preventing outside air from flowing out. The purpose is to prevent suction, etc.

[Means to solve the problem]

In order to achieve the purpose, the exhaust gas duct for a smelting reduction furnace of the present invention has an inlet part airtightly and rotatably connected to the mouth of the smelting reduction furnace, and at least two or more parts provided in the middle of the duct. It is characterized by having a movable joint.

Here, the inlet side and movable joint of the exhaust gas duct is an extensible pipe with a spherical joint structure and bellows.

Rotary joints etc. are used. Alternatively, the inlet duct part of the furnace mouth may be fixedly arranged, and three or more movable joints may be provided between the inlet duct part and the outlet duct part.

[Effect]

In the smelting reduction method, unlike conventional converter blowing, it is desirable for refining to leave a relatively large amount of molten metal remaining in the furnace as a seed metal. Therefore, tapping is performed at an inclination angle of approximately 30 degrees or less, without tilting the furnace body to a nearly horizontal state as in conventional converter tapping.

Therefore, the exhaust gas duct has a multi-joint structure so that the inlet side of the exhaust gas duct is always hermetically connected to the furnace mouth of the smelting-reduction furnace within this angle of inclination.

With this multi-joint structure, changes in the angle and position of the exhaust gas duct due to tilting of the furnace body are absorbed as changes in the angle of each joint and changes in the position of the duct portion between the joints. Therefore, the inlet side of the exhaust gas duct is always hermetically connected to the furnace mouth of the smelting reduction furnace, and is also hermetically connected to the fixed part connected to the preliminary reduction furnace, preheating furnace, waste heat boiler, etc. the result,
Even when the furnace body is tilted during tapping, the exhaust gas and exhaust heat generated in the furnace do not dissipate to the outside, and outside air does not enter the exhaust gas hood.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 is a schematic diagram showing a smelting reduction furnace equipped with an exhaust gas duct in a first embodiment.

In this embodiment, a converter type melting reduction furnace is used. This furnace body 1 always contains a molten metal bath 2 of a predetermined amount or more.
is stored, and the upper surface of the molten metal bath 2 is covered with a slag layer 3. The iron ore charged into the furnace comes into contact with the molten metal bath 2 and the slag layer 3, and is melted and reduced. As a result, as the blowing continues, the amount of the molten metal bath 2 increases and its height increases. Therefore, this increased amount is discharged from the tap water outlet 4. Further, when the slag layer 3 becomes thick, the slag is appropriately discharged from the slag outlet 5.

The furnace mouth 6 of the furnace body 1 is formed into a spherical convex shape as shown in the figure. On the other hand, an exhaust gas duct 7 that contacts this furnace port 6
The 0-input side portion 8 is formed into a spherical concave flange. Then, the inlet side portion 8 is pressed against the furnace mouth 6 by a pressure mechanism 9 such as a spring or hydraulic pressure. In this way, the furnace opening 6 and the entrance part 8
By using a spherical joint between the furnace body 1 and the furnace body 1, even if the position of the furnace mouth 6 is slightly shifted due to the tilting of the furnace body 1, the displacement of the furnace body 1 is absorbed by the bending of the exhaust gas duct 7.

Therefore, airtightness between the furnace body 1 and the exhaust gas duct 7 is maintained.

The exhaust gas duct 7 includes an inlet duct part 7a, an intermediate duct part 7b, and a fixed outlet duct part 7C. Each of the duct parts 7a to 7C is made of steel and has a water cooling structure (not shown), and has a structure that can withstand the heat of the exhaust gas passing through the inside. A joint 10 between the inlet duct part 7a and the intermediate duct part 7b and the intermediate duct part 7b
The joint 11 between the outlet duct portion 7C and the outlet duct portion 7C also has a spherical joint structure similar to the relationship between the furnace mouth 6 and the inlet portion 8. Note that the symbols r1°r2. in FIG. r3 indicates the radius of curvature of these spherical joint structures.

In addition, on the downstream side of the fixed outlet duct section 7C, there are collection and purification equipment such as a cyclone 12 for collecting dust discharged from the furnace body 1 and a bag filter 13 for removing fine powder and purifying the exhaust gas. It is provided.

The exhaust gas purified by these facilities is discharged from the chimney 15 by the blower 14. In addition, a preliminary reduction furnace, preheating furnace, exhaust heat boiler, etc. are installed in the middle of this exhaust route.
The effective use of exhaust gas and exhaust heat is the same as in the prior art, and these are omitted in FIG.

When the furnace body 1 is tilted during tapping, the entry side portion 8 moves following the rotation of the furnace mouth 6, as shown in FIG. With this movement, the inlet duct portion 7a is inclined, and the intermediate duct portion 7b is inclined so as to offset the inclination. In this way, regardless of the tilting of the furnace body 1, the airtightness between the furnace mouth 6 and the inlet part 8 is maintained, and the exhaust gas and waste heat are transferred to the fixed outlet duct part 7C.
guided by.

Here, since the joint 10 is provided between the inlet duct part 7a and the intermediate duct part 7b, the displacement of the furnace body 1 directly becomes a large amount of movement and affects the fixed outlet duct part 7C. Never.

Note that the more joints the exhaust gas duct 7 has, the more accurately it can respond to the displacement of the furnace body 1. However, since this complicates the structure of the exhaust gas duct 7 itself, it is practically preferable to have about 3 to 4 joints including the joint between the furnace mouth 6 and the inlet part 8.

FIG. 3 shows a second embodiment employing a joint with bellows.

In this embodiment, a water-cooled partition pipe 21 is tightly connected to the furnace mouth 6 of the furnace body 1, and a bellows 22 that connects the furnace mouth 6 and the inlet duct portion 7a is provided around the water-cooled partition pipe 21. The water-cooled partition pipe 21 suppresses the influence of the heat of the exhaust gas rising inside the inlet duct portion 7a on the bellows 22. The bellows 22 is made of heat-resistant steel or heat-resistant cloth.

In this way, the first joint 23 is provided between the furnace body 1 and the inlet duct portion 7a.

Further, a second joint 24 and a third joint 25 having similar bellows 22 are provided between the inlet duct part 7a and the intermediate duct part 7b and between the intermediate duct part 7b and the outlet duct part 7C. . Note that in order to thermally protect the bellows 22, a water cooling mechanism may be attached to the bellows 22.

FIG. 4 shows a state in which an exhaust gas duct having this type of joint is bent to follow the tilting movement of the furnace body 1. In this case, the displacement of the furnace body 1 is absorbed by the expansion and contraction of the bellows 22 in addition to the inclination of the inlet duct part 7a and the intermediate duct part 7b, so that it is possible to cope with minute movements.

FIG. 5 shows a third embodiment employing a rotary joint. In this example, a mixed pig iron furnace type is used as the smelting reduction furnace.

The furnace body 1 of the melting reduction furnace is rotatable about the furnace axis by a rotation mechanism 51. An inlet duct portion 52 is attached to the furnace wall of the furnace body 1. An intermediate duct section 53,54 and a fixed outlet duct section 55 are successively connected to this inlet duct section 52 by rotary joints 56, 57 and 58. As these rotary joints 56, 57, and 58, a structure called a so-called swivel joint is used.

As shown in the cross-sectional view of FIG. 6, the inlet duct portion 52 has an end surface that comes into contact with a flange 59 provided at the furnace mouth of the furnace body 1, and is pressed against the flange 59 by a pressurizing means such as a spring or a hydraulic cylinder. Pressing or clamping. At the time of tapping, the rotating mechanism 51 rotates the furnace body 1 in order to flow out the molten metal from the tap hole 60 provided on the furnace wall of the furnace body 1.
Rotate.

Along with this rotation, the flange 59 tilts as shown by the one-dot chain line or the two-dot chain line, and this movement causes the inlet duct portion 5
2 also follows. Pulled by the movement of this inlet duct) 952, the intermediate duct portions 53 and 54 are also displaced. At this time, the angle of the intermediate duct part 53 with respect to the inlet duct part 52, the angle of the intermediate duct part 54 with respect to the intermediate duct part 53, and the angle of the outlet duct part 55 with respect to the intermediate duct part 54 change at the rotary joints 56, 57, and 58. .

Therefore, even if the straight-line distance between the downstream end of the inlet duct part 52 and the inlet end of the fixed outlet duct part 55 changes, the displacement view will change depending on the inclination of each intermediate duct part 53,54. The exhaust gas and exhaust heat generated in the furnace can be efficiently guided to the outlet duct 55 without breaking the airtightness between the furnace mouth of the furnace body 1 and the inlet duct 52.

〔Effect of the invention〕

As explained above, in the present invention, by providing a plurality of movable joints in the middle of the exhaust gas duct, the airtightness of the exhaust gas passage can be maintained even when the furnace body of the smelting reduction furnace is tilted during tapping. can be maintained. Therefore, outside air does not enter into the exhaust gas discharged from the furnace.
Furthermore, exhaust gas and exhaust heat are no longer dissipated into the outside air.

Therefore, when exhaust gas and exhaust heat are used in post-processes such as a pre-reducing furnace, a preheating furnace, and an exhaust heat boiler, fluctuations in the composition and temperature of the exhaust gas are reduced, and the operating conditions of these devices are stabilized.

In addition, since the exhaust gas and exhaust heat can be led out of the system while being isolated from the outside air, it becomes easier to operate the furnace while maintaining high pressure.As a result, slag forming and spitting can be performed easily. This also makes it possible to operate with less heating.

Moreover, since the exhaust gas is compressed and sent in a small volume state, the load on the exhaust gas treatment system is also improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a smelting reduction furnace equipped with an exhaust gas duct used in the first embodiment of the present invention, FIG. 2 shows the smelting reduction furnace in a tilted state, and FIGS. Figure 4 is a diagram explaining the second embodiment, and Figures 5 and 6 are diagrams for explaining the second embodiment.
The figure is a diagram explaining the third embodiment. 1: Furnace body 2: Molten metal bath 3 Varnish slag layer 4.60: Tap tap 5: Slag tap
6: Lower type: Exhaust gas duct 7a, 52: Inlet duct part 7
b, 53.54: Intermediate duct part 7c, 55: Outlet duct part 8: Inlet side part 9: Pressure mechanism 10.1
1: Spherical joint 12: Cyclone 13: Bag filter 14 Ni blower 15: Chimney
21: Water-cooled partition pipe 22: Bellows 23.
24.25: Joint 51: Rotation mechanism 56-5
8: Rotating joint 59: Flange 60: Patent applicant for the sprue: Nippon Steel Co., Ltd. Managing Director
Masu Kobori (and 2 others) Figure 3 Figure 4

Claims (1)

[Claims] 1. The duct is characterized by comprising: an inlet portion airtightly and rotatably connected to the mouth of the smelting reduction furnace; and at least two movable joints provided in the middle of the duct. Exhaust gas duct for smelting reduction furnace. 2. An exhaust gas duct for a smelting-reduction furnace, wherein at least one of the entry side portion and the movable joint according to claim 1 has a spherical joint structure. 3. An exhaust gas duct for a smelting-reduction furnace, wherein at least one of the entry side portion and the movable joint as set forth in claim 1 is a telescopic tube provided with a bellows. 4. An exhaust gas duct for a smelting-reduction furnace, characterized in that at least one of the entry side portion and the movable joint as set forth in claim 1 is a rotary joint. 5. Fix the inlet duct part at the furnace entrance of the melting reduction furnace, connect the inlet duct part to the outlet duct part via one or more intermediate duct parts, and install a movable joint between each duct part. An exhaust gas duct for a smelting reduction furnace, characterized by being provided with.