Blast furnace profile with long service life

Abstract

The utility model belongs to the technical field of blast furnace ironmaking, and particularly relates to a blast furnace profile. The long-life blast furnace profile is composed of a cylinder and a circular truncated cone and comprises a furnace throat, a furnace body, a bosh and a hearth, and the bosh blast furnace is 50% of a conventional blast furnace; the included angle between the side wall of the furnace throat and the horizontal line is 85-90 degrees; the included angle between the side wall of the furnace body and the horizontal line is 81-84 degrees; the included angle between the side wall of the bosh and the horizontal line is 74-80 degrees. Compared with the prior art, the utility model has the advantages that: 1, a furnace bosh straight tube section is removed, the height of the furnace body is increased, and the diameter of the furnace body is gradually increased from top to bottom, so that furnace charge can be well absorbed to be heated and expanded; the height of the bosh is reduced, the bosh is located below a soft melting zone and located in a wet zone, stable slag crust can be hung on the hot face of the cooling wall easily, and the service life of the cooling wall can be longer than 15 years;

Description

Technical Field

[0001] The utility model belongs to the technical field of blast furnace ironmaking, and particularly relates to a blast furnace profile. Background Art

[0002] A blast furnace is a vertical ironmaking furnace with a circular cross-section. Its profile mainly consists of five parts: the throat, the shaft, the bosh, the hearth, and the hearth bottom. The structural characteristics and functions of each part are as follows:

[0003] 1) Throat: It is cylindrical and located at the top of the blast furnace.

[0004] 2) Shaft: It is a regular truncated cone and its height accounts for 50% - 60% of the effective height of the blast furnace. Its function is to adapt to the volume expansion of the burden after heating, which is beneficial to reducing the frictional resistance of the burden descent and avoiding the formation of a charge arch. At the same time, it adapts to the volume contraction of the coal gas flow after cooling to ensure a certain coal gas flow rate and guarantee the heat and mass transfer processes between the gas and the burden.

[0005] 3) Bosh: It is the part with the largest diameter in the blast furnace profile and is a cylindrical space. Its function is that the bosh is exactly the softening and melting zone of smelting, where the gas permeability becomes poor. Its existence expands the lateral space of this part, improving the gas permeability conditions. And it plays a connecting role in the profile structure, making the transition from the hearth to the shaft gentle and reducing dead zones.

[0006] 4) Hearth: It is located above the hearth bottom and is an inverted truncated cone. Its functions are as follows: First, the shape of the hearth adapts to the volume contraction of the burden after melting and dripping, stabilizing the charging speed. Second, it can make the high-temperature coal gas flow away from the furnace wall, which not only does not burn the furnace wall but also is beneficial to the stability of the slag skin. Third, a large amount of high-temperature gas is generated in the combustion zone, and the gas volume expands violently. The existence of the hearth adapts to this change.

[0007] 5) Hearth bottom: The lower cylindrical part of the blast furnace profile is the hearth bottom. Tuyeres, slag notches, and tapholes are respectively arranged at the upper, middle, and lower parts of the hearth bottom.

[0008] A reasonable profile is the basic condition for realizing high output, stable production, low consumption, and long life of the blast furnace. However, the profile design is not simple because the raw material and fuel conditions, production operation systems, subsequent change trends, etc. of the blast furnace are crucial to it. There are many index parameters and they affect each other. The differences in raw material sources, production modes, management systems, etc. of different customers also lead to strong personalized requirements for customers in profile design. When designing the blast furnace profile, various factors need to be comprehensively considered to ensure the efficient operation and good performance of the blast furnace. At the same time, with the continuous progress of technology and the change of production requirements, the blast furnace profile is also constantly developing and optimizing.

[0009] However, with the enlargement of blast furnaces, especially for 3000m 3For blast furnaces of the above type, with the increase in the height and diameter of the blast furnace, the stress conditions in the bosh and hearth of the blast furnace have also changed significantly. The cooling stave in the lower part of the hearth and the upper part of the bosh is severely damaged. According to statistics, the average service life is 6.2 years, far lower than the requirement that the service life of a blast furnace generation is greater than 15 years. The cooling stave in the lower part of the hearth and the upper part of the bosh has become a key factor restricting the service life of the blast furnace. The form of its damage is the abrasion of the cooling stave by the burden, and the specific reasons for the abrasion are as follows:

[0010] 1) With the intensification of smelting in the blast furnace, the position of the cohesive zone drops. This part is above the cohesive zone and belongs to the dry zone, where it is difficult to form a stable slag skin;

[0011] 2) After the blast furnace is enlarged, with the increase in the height and diameter of the blast furnace, in the turning point area of the bosh and hearth, since the direction of the principal stress changes from the vertical axial direction to the horizontal direction, the change in the particle flow direction for the convergence (restricted by the static dead zone and the furnace wall) of the burden descent increases the stress at this part; Measuring the vertical and / or horizontal stress during the particle flow process using a cold-state model of the blast furnace shows that there is a significant increase in the horizontal stress at the wall surface in the transition area near the convergent part of the bosh.

[0012] Katayama and D. Pomeroy, a basic researcher at ArcelorMittal Global Research and Development, studied the vertical pressure generated by the countercurrent particles and gas flow on the hearth and furnace wall using experimental models and mathematical models. Their research can well explain this point. Their research results show that: the mixed burden generates the greatest pressure on the furnace wall at the bosh part, and the pressure generated at the interface between the bosh and the hearth is also much greater than that at the lower part of the furnace shaft and the lower part of the bosh. Since the pressure on the furnace wall of the bosh and the upper part of the hearth is much higher than that of other parts, when the copper cooling stave is worn under the condition of losing the protection of the slag skin, obviously the wear of the copper cooling stave at these two parts will be significantly greater than that of other parts.

[0013] 3) The diameter of the bosh affects the pressure on the furnace wall. For large blast furnaces, the larger the diameter of the bosh, the greater the pressure on the furnace wall.

[0014] D. Pomeroy also studied the influence of the bosh radius on the pressure on the furnace wall. The results show that: at the same furnace body height, there is a specific bosh radius that makes the pressure on the furnace wall at the furnace shaft / bosh interface reach the maximum. At this time, reducing the bosh radius will not reduce the pressure at this place much, while increasing the bosh radius will reduce the pressure at this place significantly; and the pressure on the furnace wall at the bosh / hearth interface increases rapidly with the increase in the bosh diameter. When the bosh diameter increases from 6.2 m to 7.55 m, the pressure on the furnace wall at this place increases from 104 kPa to 222 kPa.

[0015] 4) The burden is charged from the throat of the furnace and is heated during the descent process. The temperature rises from room temperature to above 1200 °C, and along with the reduction reaction of iron oxides, the thermal expansion of the burden increases the stress at the bosh. Summary of the Invention

[0016] Aiming at the reasons for the damage of the cooling stave in the bosh and belly parts of large blast furnaces, the methods to solve the technical problems are as follows:

[0017] The long-life blast furnace hearth is composed of a cylinder and a frustum of a cone, including a throat, a shaft, a belly, and a hearth. The angle between the side wall of the throat and the horizontal line is 85-90°; the angle between the side wall of the shaft and the horizontal line is 81-84°; the angle between the side wall of the belly and the horizontal line is 74-80°.

[0018] Preferably, the throat diameter < hearth diameter < the diameter at the junction of the shaft and the belly.

[0019] Preferably, the angle between the side wall of the throat and the horizontal line is 90°.

[0020] Preferably, copper cooling staves are used in the lower part of the shaft.

[0021] Preferably, copper cooling staves are used in the belly.

[0022] Preferably, the height of the belly is less than 2m.

[0023] Preferably, H / D > 1.9.

[0024] Compared with the prior art, its advantages are:

[0025] 1. Remove the straight barrel section of the bosh, increase the height of the shaft, and the diameter of the shaft gradually increases from top to bottom, which can well absorb the thermal expansion of the burden.

[0026] 2. Reduce the height of the belly. The belly is located below the cohesive zone and in the wet zone, making it easy to form a stable slag skin on the hot surface of the cooling stave. Brief Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the blast furnace hearth

[0028] Figure 2 It is a schematic diagram of the blast furnace body

[0029] Legend Marks

[0030] 1 Blast furnace, 2 Throat, 3 Shaft, 4 Belly, 5 Hearth, 6 Belly cooling stave, 7 Lower part of shaft cooling stave, 8 Middle and upper part of shaft cooling stave, 9 Hearth cooling stave, 10 Cohesive zone, 11 Coke, 12 Sinter, pellet, lump ore, coke. Detailed Description of the Invention

[0031] The following takes Figure 1 、 Figure 2For reference, the implementation of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement it. The present invention can be embodied in many different forms and is not limited to this description.

[0032] The long-life blast furnace profile of the present utility model, the blast furnace 1 is composed of a cylinder and a frustum of a cone, including a throat 2, a shaft 3, a bosh 4, and a hearth 5. The included angle between the side wall of the throat 2 and the horizontal line is 90°; the included angle between the side wall of the shaft 3 and the horizontal line (shaft angle) is 83.74°; the included angle between the side wall of the bosh 4 and the horizontal line (bosh angle) is 75.96°.

[0033] The diameter of the throat 2 < the diameter of the hearth 5 < the diameter at the junction of the shaft 3 and the bosh 4.

[0034] The throat 2 uses a cast steel cooling stave or a cast steel plate; the middle and upper cooling staves 8 of the shaft 3 use cast iron cooling staves, and the lower cooling stave 7 of the shaft uses a copper cooling stave; the bosh cooling stave 6 uses a copper cooling stave; the height of the bosh 4 is 2.0 m, which is about 50% of that of a conventional blast furnace. The height-to-diameter ratio (H / D) of the blast furnace is equal to 1.964.

[0035] The specific dimensions of the furnace profile are as follows:

[0036] Throat diameter: 11500 mm

[0037] Lower shaft diameter: 16500 mm

[0038] Upper bosh diameter: 16500 mm

[0039] Hearth diameter: 15500 mm

[0040] Throat height: 2000 mm

[0041] Shaft height: 22800 mm

[0042] Bosh height: 2000 mm

[0043] Hearth height: 5400 mm

[0044] Shaft angle: 83.74°

[0045] Bosh angle: 75.96°

[0046] Height-to-diameter ratio: 1.964

[0047] Sinter, pellets, lump ore, and coke are charged batchwise into the throat 2 of blast furnace 1 through the top charging equipment, and are charged alternately, one can of ore and one can of coke. The burden is stratified in the furnace, with one layer of coke and one layer of ore; the burden moves from top to bottom, and high-temperature oxygen-rich air is blown into the furnace through the tuyeres. Coke and pulverized coal burn in the tuyere area, generating a large amount of heat and gas. The gas moves from bottom to top, passing through the cohesive zone, ore layer, and coke layer. During the movement, the gas transfers heat to the iron ore, and the iron ore is heated and reduced by CO and hydrogen in the gas. The iron ore expands after being heated, and the furnace body 3 gradually expands from top to bottom to accommodate the expansion of the iron ore; when the iron ore is heated to about 1000 - 1200 °C, the cohesive zone 10 is formed. The cohesive zone 10 consists of coke windows and softened ore, and the gas moves from bottom to top through the coke windows of the cohesive zone 10. The root of the cohesive zone 10 is located at the junction of the hearth 4 and the bosh 3. Above the cohesive zone 10 are sinter, pellets, lump ore, and coke 12, and below the cohesive zone 10 is coke 11. The hearth 4 is located below the cohesive zone 10 and belongs to the wet zone. The slag adheres to the hot surface of the hearth cooling stave 6 to form a stable slag shell, protecting the hearth cooling stave 6 from being worn and damaged.

[0048] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A long-life blast furnace profile, characterized in that, The furnace type is composed of a cylinder and a frustum of a cone, including a furnace throat, a furnace body, a furnace belly, and a hearth. The angle between the side wall of the furnace throat and the horizontal line is 85-90°; the angle between the side wall of the furnace body and the horizontal line is 81-84°; the angle between the side wall of the furnace belly and the horizontal line is 74-80°.

2. The long-life blast furnace hearth as claimed in claim 1, wherein, The diameter of the furnace throat < the diameter of the hearth < the diameter at the junction of the furnace body and the furnace belly.

3. A long-life blast furnace profile as claimed in claim 1, characterized in that, The angle between the side wall of the furnace throat and the horizontal line is 90°.

4. A long-life blast furnace profile as described in claim 1, characterized in that, The lower part of the furnace body adopts copper cooling stave.

5. A long-life blast furnace profile according to claim 1, characterized in that, The furnace belly adopts copper cooling stave.

6. A long-life blast furnace profile as claimed in claim 1, characterized in that, The height of the furnace belly is less than 2m.

7. A long-life blast furnace profile according to claim 1, characterized in that, H / D > 1.9.

Images