Long-service-life blast furnace

Abstract

Disclosed in the present invention is a long-service-life blast furnace. By optimizing the design of parts such as a bosh and a belly, and the design of a copper stave body, the objective of reducing damage to a copper stave is achieved, and safe and stable production of the blast furnace is maintained. The problem of short service life of blast furnaces caused by disappearance of hot-face bosses of copper staves and stave deformation due to different furnace charges in the blast furnaces having different degrees of damage to the copper staves is solved.

Description

Long service life blast furnace TECHNICAL FIELD

[0001] The present application relates to a long service life blast furnace, and belongs to the technical field of blast furnaces. BACKGROUND

[0002] Due to the damage and water leakage of copper cooling staves of large and medium-sized blast furnaces, regular intermediate repair or early major repair is often caused, which not only affects the safe production of the blast furnace, but also shortens the service life of the blast furnace. At present, the copper cooling stave is mainly composed of the lower part of the blast furnace shaft, the bosh and the belly. This area is the high-temperature zone of the blast furnace. The good thermal conductivity of copper is used to guide the heat out of the cooling water in the copper cooling stave, so as to achieve the effect of safe and stable production of the blast furnace. However, due to the double effects of high-temperature gas flow erosion and charge descending abrasion, the bosh and the belly of the blast furnace are prone to damage. Although copper has good thermal conductivity, it has poor wear resistance and is prone to deformation. According to the investigation of the damage of many domestic blast furnaces, the damage of the copper cooling stave is mainly abrasion, accompanied by deformation, and the abrasion part is mainly in the lower part of the bosh and the upper part of the belly. After the abrasion of the copper cooling stave, the slag hanging capacity becomes poor, and the frequent falling of the slag skin not only easily causes the fluctuation of the furnace condition, but also brings safety hazards. It is found that whether in the horizontal direction or in the vertical direction, there is generally a gap of 30-40mm between two copper cooling staves, which is filled with filler, and the thermal conductivity of the filler is quite different from that of the copper cooling stave, which has a certain influence on the overall thermal conductivity of the blast furnace.

[0003] At present, the volume of the bosh of the blast furnace accounts for 10-13% of the effective volume of the blast furnace. The volume of the bosh is small, and the cooling stave of the bosh and the belly is prone to wear and tear. When the hot face boss disappears and the wall body deforms, it is difficult for the slag skin formed by the cooling of the copper cooling stave in the wall surface to stably adhere to the copper cooling stave. After repeated air flow erosion and charge abrasion, the service life of the blast furnace is shortened.

[0004] Patent application CN115982875A provides a design method of a long service life blast furnace. By optimizing the blast furnace belly, an upper and lower belly angle is set. The angle range of the upper belly angle is 77-81°, and the angle range of the lower belly angle is 60-75°. The position of the lower belly angle is 25% to 50% of the height of the belly. The shaft angle at the bottom of the shaft is between 81-83°. The volume of the bosh accounts for 14-16% of the effective volume of the blast furnace. The volume of the bosh accounts for 14-16% of the effective volume of the blast furnace, which provides more space for the expansion of iron ore, thereby prolonging the service life of the blast furnace.

[0005] The patent application CN115094176A forms a composite structure of the cast iron or cast steel cooling wall body and the special-shaped copper pipe by arranging the special-shaped copper pipe on the hot face of the cast iron or cast steel cooling wall body, so that the composite structure has the advantages of the cast iron / cast steel cooling wall and the copper cooling wall, i.e., higher wall strength, wear resistance and cooling capacity.

[0006] The short service life of large and medium-sized copper cooling walls at home and abroad has become a common problem in the industry. According to statistics, the service life of large and medium-sized copper cooling walls of blast furnaces in China is about 6.5 years. The production of blast furnaces not only faces safety problems, but also seriously affects the efficiency of blast furnaces. The stability of the slag skin on the hot face of the copper cooling wall is the key to long life, but the necessary factors for the stability of the slag skin have not been clearly defined, and the existing technology cannot solve the problem of the stability of the slag skin on the copper cooling wall.

[0007] SUMMARY

[0008] In order to solve the above-mentioned problems, prevent different charges in the blast furnace from damaging the copper cooling wall to different degrees, cause the disappearance of the convex boss on the hot face of the copper cooling wall, and further cause the short service life of the blast furnace, the present application discloses a long-life blast furnace, which optimizes the structure of the furnace waist, the furnace belly and the like, and the structure of the copper cooling wall body, so as to reduce the damage of the copper cooling wall and maintain the safety and stable production of the blast furnace. The specific technical scheme is as follows:

[0009] A long-life blast furnace, which comprises a furnace throat, a furnace body, a furnace waist, a furnace belly and a furnace hearth from top to bottom, wherein the furnace hearth is provided with a tap hole, the furnace belly of the long-life blast furnace is divided into two ends, the upper end is connected with the furnace waist, and the lower end is connected with the furnace hearth; the included angles between the top of the upper end and the lower end and the horizontal plane are respectively referred to as the upper belly angle and the lower belly angle; the angle of the upper belly angle is between 77-81°, and the angle of the lower belly angle is between 60-75°; the position of the lower belly angle is 25% to 50% of the height of the furnace belly; the furnace angle of the bottom of the furnace body is between 81-83°; and the volume ratio of the furnace waist to the effective volume of the blast furnace is between 14-16%.

[0010] Further, the ratio of the height of the furnace waist to the height of the furnace belly is between 1-1.2.

[0011] Further, the refractory embedded in the hot face of the cooling wall around the wall surface area of the upper belly angle uses silicon carbide refractory.

[0012] Further, the long-life blast furnace uses copper or cast iron cooling wall in the furnace waist and the furnace belly, and the refractory embedded in the hot face of the cooling wall around the wall surface area of the lower belly angle uses graphite refractory, and the thermal conductivity of the graphite refractory is higher than 100 W / (m.K).

[0013] Further, in the circumferential direction, the two sides of the copper cooling wall are designed as n convex bosses, wherein n≥1, and adjacent two copper cooling walls can be connected through the convex bosses.

[0014] In the vertical direction, the top surface and the bottom surface of the copper cooling wall are respectively designed as n bosses, wherein n is greater than or equal to 1, and adjacent two copper cooling walls are connected through the bosses;

[0015] The gap at the boss insertion position of the adjacent two copper cooling walls is less than 5 mm;

[0016] The gap at the boss insertion position of the two copper cooling walls is filled with copper sheet or copper mesh, and no filler is used.

[0017] Further, the maximum diameter of the bosh of the blast furnace is also the largest part of the acceptable expansion of the furnace burden, and the bosh is the part where the blast furnace starts to shrink. If the iron ore in the bosh is still in the expansion stage, the pressure on the furnace wall will increase, which is not conducive to the stability of the slag skin. Therefore, the volume of the active zone of the blast furnace is increased as much as possible to give the furnace burden sufficient expansion space. In addition, the bosh is the part where the blast furnace profile starts to shrink. When the furnace burden reaches the bosh and the volume reaches the shrinkage state, the pressure of the furnace burden on the furnace wall can be greatly reduced. Therefore, the iron ore reaching the bosh should be in a molten state as much as possible. Therefore, the position of the root of the soft melting zone cannot be too low. Based on this, the ratio between the center gas flow index Z value and the edge gas flow index W value is in the range of 18-22, the center gas flow index Z value is in the range of 12-20, the edge gas flow index W value is in the range of 0.6-1.0, and the edge gas flow temperature is not less than 105 DEG C.

[0018] The distance between the outermost ore drop point and the furnace wall is 300-500 mm;

[0019] The active zone of the blast furnace hearth accounts for more than 0.6, wherein the calculation formula of the active zone of the blast furnace hearth a is as follows: R = 0.88 + 0.000092E-0.00031XP c / n+L 伸 ,

[0020] D R --convolution zone depth, m;

[0021] E--blowing kinetic energy, kg·m / s;

[0022] P c --coal injection amount, kg / h;

[0023] d--hearth diameter, m;

[0024] L 伸 --tuyere insertion length, m;

[0025] a--active zone of blast furnace hearth.

[0026] The working principle of the present application is:

[0027] Copper cooling wall is a key component in blast furnace, and its service life is directly related to the stable operation and economic benefits of blast furnace. In order to comprehensively solve the service life problem of copper cooling wall, it is necessary to comprehensively consider three aspects of blast furnace design, copper cooling wall design and blast furnace operation system. Since the large blast furnace is limited in the height direction, the furnace capacity can only be expanded in the radial direction, in order to ensure sufficient furnace waist volume, the furnace waist diameter becomes larger and larger, and the furnace bosh angle becomes smaller and smaller. The too small furnace bosh angle will affect the gas flow distribution of the blast furnace, make the edge gas flow weak, cause the softening zone of the blast furnace to be low, make the slag skin of the furnace wall unstable, and cause the copper cooling wall to be damaged early.

[0028] The service life of copper cooling wall is a systematic project, which is not only related to the design and manufacture of copper cooling wall, but also closely related to the design of blast furnace. The present application starts from the design of blast furnace, optimizes the design of furnace waist, furnace bosh and other parts, reduces the damage of copper cooling wall, and maintains the safety and stable production of blast furnace.

[0029] The beneficial effects of the present application are:

[0030] The furnace waist volume is expanded, the space of the iron ore expansion stage is increased, and the wear of the furnace wall is reduced. The double bosh angle structure is designed between 77-81° of the upper bosh angle, so that there is enough gas flow through the edge of the furnace waist, and the silicon carbide refractory is used, which has good wear resistance. The lower bosh angle is designed to be 60-75°, combined with graphite refractory, which has good heat conductivity. In the area close to the tuyere, it is easier to form a stable slag skin on the hot surface, and the smaller lower bosh angle plays a good supporting role on the upper slag skin. Under the premise of ensuring sufficient expansion space of iron ore, the ratio of bosh angle, shaft angle and bosh waist height is controlled in the above scheme range, which plays a role in reasonably controlling the edge gas flow, ensuring the stability of the furnace wall slag skin and prolonging the service life of the blast furnace cooling equipment.

[0031] The present application can effectively solve the service life problem of copper cooling wall by comprehensively considering the factors of blast furnace design, copper cooling wall design and blast furnace operation system. BRIEF DESCRIPTION OF DRAWINGS

[0032] Fig. 1 is a schematic diagram of the long-life blast furnace of the present application,

[0033] Fig. 2 is a schematic diagram of the bosh part of the long-life blast furnace of the present application,

[0034] Fig. 3 is a schematic diagram of the connection of two adjacent copper cooling walls in the circumferential direction of the present application by the insertion of a boss,

[0035] Fig. 4 is a schematic diagram of the connection of two adjacent copper cooling walls in the vertical direction of the present application by the insertion of a boss,

[0036] Figure 5 is the boss design of the copper cooling wall in the circumferential direction of the blast furnace in the embodiment of the present application,

[0037] In the figure: 1 - furnace throat; 2 - shaft; 3 - bosh; 4 - belly; 5 - hearth; 6 - taphole; 7 - upper bosh angle; 8 - lower bosh angle; 9 - shaft angle. DETAILED DESCRIPTION

[0038] The present application will be further illustrated in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present application and are not used to limit the scope of the present application.

[0039] The long-life blast furnace meets the design requirements of the future

[0040] (1) Blast furnace design:

[0041] A design method of a long-life blast furnace, the long-life blast furnace comprising a furnace throat, a shaft, a bosh, a belly, a hearth and a taphole, the belly of the long-life blast furnace being provided with upper and lower bosh angles, the angle of the upper bosh angle being in the range of 77-81°, the angle of the lower bosh angle being in the range of 60-75°; the position of the lower bosh angle being 25% to 50% of the height of the belly; the shaft angle at the bottom of the shaft being between 81-83°; the volume of the bosh accounting for 14-16% of the effective volume of the blast furnace.

[0042] The ratio of the height of the bosh to the height of the belly is between 1-1.2.

[0043] The refractory used for the hot surface inlay of the wall surface area around the upper bosh angle is silicon carbide refractory.

[0044] The blast furnace uses copper or cast iron cooling wall in the bosh and the belly, the refractory used for the hot surface inlay of the wall surface area around the lower bosh angle is graphite refractory, the thermal conductivity of the graphite refractory is higher than 100 W / (m.K).

[0045] (2) Copper cooling wall design

[0046] In the circumferential direction, the two sides of the copper cooling wall are designed as n bosses, where n≥1, adjacent two copper cooling walls can be connected through the bosses, as shown in Figure 3;

[0047] In the vertical direction, the top surface and the bottom surface of the copper cooling wall are designed as n bosses, where n≥1, adjacent two copper cooling walls can be connected through the bosses, as shown in Figure 4;

[0048] On the basis of meeting (1) and (2), the gap at the boss interpenetration of adjacent two copper cooling walls is not more than 5mm;

[0049] On the basis of meeting (1), (2) and (3), the gap at the boss interpenetration of two copper cooling walls is filled with copper sheet or copper mesh to fill the gap, without using filler.

[0050] (3) Blast furnace operation system optimization

[0051] The ratio between the blast furnace center gas flow index Z value and the edge gas flow index W value ranges from 18 to 22, the center coal gas flow index Z value ranges from 12 to 20, the edge coal gas flow index W value ranges from 0.6 to 1.0, and the edge coal gas flow temperature is not lower than 105 DEG C;

[0052] The outermost ore drop point is 300-500mm away from the furnace wall;

[0053] The blast furnace hearth active area ratio reaches 0.6 or above, wherein the calculation formula of the hearth active area ratio a is as follows: R = 0.88 + 0.000092E - 0.00031*P c / n + L 伸 ,

[0054] In the formula, D R is the whirl area depth, m;

[0055] E is the blast kinetic energy, kg*m / s;

[0056] P c is the coal injection amount, kg / h;

[0057] d is the hearth diameter, m;

[0058] L 伸 is the tuyere insertion length, m;

[0059] a is the blast furnace hearth active area ratio.

[0060] Advantages of the present application:

[0061] (1) After using the above scheme, the furnace belly volume is expanded, the space of the iron ore expansion stage is increased, and the wear of the furnace wall is reduced. The double bosh angle structure, the upper bosh angle is designed to be between 77-81 DEG, so that there is enough coal gas flow through the edge of the furnace waist, and the silicon carbide refractory is used, which has good wear resistance. The lower bosh angle is designed to be 60-75 DEG, combined with graphite refractory, which has good thermal conductivity, and is more likely to form a stable slag skin on the hot surface in the area close to the tuyere. The smaller lower bosh angle plays a good supporting role on the upper slag skin. Under the premise of ensuring sufficient expansion space for iron ore, the bosh angle, shaft angle and bosh waist height ratio are controlled within the above scheme range, which plays a role in reasonably controlling the edge gas flow, ensuring the stability of the furnace wall slag skin and prolonging the service life of the blast furnace cooling equipment.

[0062] (2) After the above improvement measures, the gap between adjacent copper cooling walls is covered with copper material, the heat conduction performance at the gap is greatly improved, and the overall heat conduction of the blast furnace in the circumferential direction and the vertical direction tends to be uniform. At the same time, due to the design of the boss at the gap, the fixing of the copper cooling wall is enhanced, and the deformation of the copper cooling wall is reduced.

[0063] (3) After the above technology is used in the blast furnace operation system, the gas flow distribution and the softening zone position are regulated and controlled, and the stability of the slag skin of the furnace wall is maintained. The lower air supply system is optimized, the proportion of the active zone of the hearth is regulated and controlled, the volume of the dead coke is reduced, and sufficient expansion space is given to the furnace charge before melting; the upper distribution system is optimized, the reasonable gas flow distribution is regulated and controlled, the position of the root of the softening zone is avoided to be too low, the furnace shrinkage and the charge shrinkage are adapted, and the stability of the copper cooling wall slag skin is realized.

[0064] An embodiment of the present application in specific use is given below:

[0065] Shagang 2680m 3 After the above invention is used in the 2680m blast furnace, the copper cooling wall at the lower part of the shaft, the waist and the belly of the furnace is used for 2 generations of furnace service, and the service life reaches more than 18 years, which is the longest copper cooling wall in China, and there is no damage in the use process. The specific index parameters are shown in the following table:

[0066] Table 1 Shagang 2680m blast furnace design parameters

[0067] 2680m 3 The design of the copper cooling wall of the blast furnace is shown in Figure 5, the boss connection mode is used in the circumferential direction, the gap between adjacent copper cooling walls is reduced, and the circumferential heat transfer efficiency of the copper cooling wall is improved.

[0068] Shagang 2680m 3 On the lower operation system of the blast furnace, on the one hand, the length of the tuyere small sleeve inserted is increased to 490mm, and on the other hand, the blast kinetic energy is increased to 12000kg.m / s, the proportion of the active zone of the hearth of the blast furnace reaches 0.63, the volume of the dead coke is reduced, and sufficient expansion space is given to the furnace charge.

[0069] In terms of the upper operation system, the distribution matrix is adjusted, the outermost landing point of the ore is about 3450mm away from the furnace wall, the edge temperature of the cross temperature gun is about 120℃, the gas flow distribution index W is about 0.85, and the Z / W value is about 19, which avoids the position of the root of the softening zone to be too low, and makes the charge shrinkage and the furnace shrinkage adapt to each other.

[0070] After the above invention is used, Shagang 2680m 3The service life of the copper cooling wall of the blast furnace reaches 18 years, and the service life of the partial used copper cooling wall reaches 23 years, which is the longest service life of the copper cooling wall in China at present, and not only guarantees the safety production, but also brings great benefits for the enterprise.

[0071] The technical means disclosed in the technical scheme of the present application is not limited to the technical means disclosed in the above technical means, and also includes technical schemes composed of any combination of the above technical features.

[0072] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents in the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. A long-life blast furnace, characterized in that: The longevity blast furnace comprises, from top to bottom, a furnace throat, a furnace body, a furnace waist, a furnace bosh and a hearth. The hearth is provided with an iron mouth. The furnace bosh of the longevity blast furnace is divided into an upper and lower through-going end. The top of the upper end is connected to the furnace waist, and the bottom of the lower end is connected to the hearth. The angles between the top of the upper end and the top of the lower end and the horizontal plane are respectively called the upper furnace bosh angle and the lower furnace bosh angle. The angle range of the upper furnace bosh angle is between 77-81°, and the angle range of the lower furnace bosh angle is between 60-75°; the position of the lower furnace bosh angle is 25% to 50% of the furnace bosh height; the furnace body angle at the bottom of the furnace body is between 81-83°; the proportion of the furnace waist volume to the effective volume of the blast furnace is between 14-16%.

2. The long-life blast furnace according to claim 1, characterized in that: The ratio of the furnace waist height to the furnace bosh height is between 1-1.

2.

3. The long-life blast furnace according to claim 1, characterized in that: The refractory material embedded in the hot surface of the cooling wall in the wall area surrounding the upper furnace belly angle is made of silicon carbide refractory material.

4. The long-life blast furnace according to claim 1, characterized in that: The blast furnace uses copper or cast iron cooling walls at the furnace waist and furnace belly, and the refractory material embedded in the hot surface of the cooling wall area around the lower furnace belly corner is graphite refractory, and the thermal conductivity of the graphite refractory is higher than 100W / (mK).

5. The long-life blast furnace according to claim 1, characterized in that: In the circumferential direction, the two sides of the copper cooling stave are designed as n-section bosses, where n ≥ 1, and two adjacent copper cooling staves can be connected through the bosses; In the vertical direction, the top and bottom surfaces of the copper cooling staves are designed as n-section bosses, where n ≥ 1. Two adjacent copper cooling staves can be connected through the bosses. The gap between two adjacent copper cooling wall bosses shall not exceed 5mm; The gap between the two copper cooling wall bosses is filled with copper sheets or copper mesh instead of fillers.

6. The long-life blast furnace according to claim 1, characterized in that: The ratio between the center gas flow index Z value and the edge gas flow index W value of the blast furnace is in the range of 18-22, the center gas flow index Z value is in the range of 12-20, the edge gas flow index W value is in the range of 0.6-1.0, and the edge gas flow temperature is not lower than 105°C; The outermost ore landing point is 300-500mm away from the furnace wall; The proportion of the blast furnace hearth active area reaches more than 0.6, and the calculation formula of the hearth active area proportion a is as follows: D R =0.88+0.000092E-0.00031×P c / n+L 伸 , Where D R ——depth of raceway, m; E——Blast kinetic energy, kg·m / s; P c ——coal injection rate, kg / h; d——diameter of furnace, m; L 伸 ——Length of air inlet, m; a——Proportion of active area of ​​blast furnace hearth.

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