Furnace shell repairing method for blast furnace top combustion type hot blast stove

Abstract

The invention relates to a method for repairing a furnace shell of a top combustion type hot blast stove of a blast furnace, belongs to the field of ferrous metallurgy, and aims to solve the problem of cracking of the furnace shell in the using process of the top combustion type hot blast stove. According to the method, an outer layer furnace shell is welded to the outer portion of a cracked furnace shell between a burner brick support and a combustion chamber brick support of the top combustion type hot blast stove, and a new overall structure is formed. And a gap is reserved between the new outer-layer furnace shell and the original inner furnace shell, so that the air pressure borne by the hot blast stove and the gas sealing effect are met. According to the invention, an outer protective layer is arranged outside the outer-layer furnace shell, so that the temperature of the outer-layer furnace shell is kept higher than the acid dew point temperature, and the influence of extreme climate on the furnace shell is reduced. Meanwhile, a device used for monitoring the displacement change of the inner furnace shell and the outer furnace shell is arranged on the outer furnace shell and used for judging the working state of the inner furnace shell and giving out early warning when the inner furnace shell fails. The general industrial problem of stress corrosion cracking of the furnace shell can be effectively solved, and safe operation of the hot-blast stove is ensured.

Description

Technical Field

[0001] The invention belongs to the field of ferrous metallurgy and relates to a method for repairing a furnace shell of a blast furnace top-fired hot blast furnace. Background Art

[0002] Since the late 1980s, the application of Shougang top-fired hot blast furnaces in large blast furnaces has marked a major breakthrough in this technology. Subsequently, top-fired hot blast furnaces represented by the Russian Kalugin type have gradually been widely used in Russia, China and other places, especially in Caofeidian 5500m 3 and Japan JFE3200m 3 The application of top-fired hot blast stoves in super-large blast furnaces has further proved its feasibility and superiority in super-large blast furnaces. Top-fired hot blast stoves have not only been applied in super-large blast furnaces, but also achieved a high blast temperature of about 1300℃, significantly improving the production efficiency of blast furnaces.

[0003] However, in actual operation, the shell of the top-fired hot blast furnace cracked under high temperature and high pressure, especially in the high temperature area of ​​the combustion chamber. These cracks first appeared in the circumferential and longitudinal welds. Although they were repaired, the cracking problem was not fundamentally solved, but instead caused the cracking of the parent material to gradually increase. Due to the repeated repair and overall replacement of the welds, each repair had different degrees of impact on the blast furnace production, and the repair effect was not long-lasting.

[0004] The causes of furnace shell cracking are complex and varied, including residual stress and fatigue stress generated during welding and processing, as well as the influence of acidic media such as chlorine and sulfur ions in blast furnace gas. These factors work together under high temperature and high pressure environments to cause stress corrosion cracking of the furnace shell. Especially under high wind temperature conditions, acidic media such as NOx, SOx, HCl, and HF generated by combustion condense on the inner surface of the furnace shell, forming an acidic corrosion environment and accelerating the cracking process of the furnace shell.

[0005] Traditional furnace shell repair methods, such as weld patching, overall replacement and annealing, have alleviated the cracking problem to a certain extent, but have not completely solved the root cause. These methods not only have limited repair effects, but also take a long time to repair, have a great impact on blast furnace production, and also have a negative impact on the service life of the refractory materials in the furnace.

[0006] Therefore, in response to the problem of furnace shell cracking that currently occurs in top-fired hot blast furnaces under large-scale and high wind temperature conditions, a more effective and thorough repair method is urgently needed to ensure production safety, extend the service life of the hot blast furnace, and promote the further development and application of top-fired hot blast furnace technology. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a method for repairing the furnace shell of a blast furnace top-fired hot blast furnace, aiming to solve the common furnace shell cracking problem that occurs in large-scale, high-temperature top-fired hot blast furnaces, and to provide a repair method that makes the furnace shell repair more thorough, minimizes the impact on the hot blast stove and the blast furnace, and can solve the subsequent cracking problem, thereby ensuring the safe operation of the hot blast stove.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for repairing a furnace shell of a top-fired hot blast furnace comprises welding an outer furnace shell to the outside of an original furnace shell that is cracked between a burner brick support and a combustion chamber brick support of the top-fired hot blast furnace, the outer furnace shell is spliced ​​into a whole in a circumferential direction, a gap is provided between the outer furnace shell and the original furnace shell, and the outer furnace shell is used to withstand the hot blast furnace gas pressure and achieve gas sealing.

[0010] Furthermore, in the furnace shell repairing method, the gap between the new outer furnace shell and the original inner furnace shell can be filled with heat-conducting or anti-corrosion materials.

[0011] Furthermore, in the furnace shell repair method, a corrugated compensator for absorbing thermal displacement is provided on the outer furnace shell.

[0012] Furthermore, in the furnace shell repair method, the outer furnace shell may be provided with a pressure equalizing pipe for pressure equalization, and the pressure equalizing gas source intake point is on the cold air pipe from the cold air valve to the hot air furnace.

[0013] Furthermore, in the furnace shell repairing method, thermometers for temperature monitoring are arranged on the original furnace shell and the outer furnace shell.

[0014] Furthermore, in the furnace shell repair method, drainage facilities are provided at the bottom of the outer furnace shell.

[0015] Furthermore, in the furnace shell repair method, the on-site welds of the outer furnace shell should be subjected to measures to eliminate welding residual stress.

[0016] Furthermore, in the furnace shell repair method, an outer protective layer is provided on the outside of the outer furnace shell to increase the temperature of the outer furnace shell and avoid the influence of extreme climate on the furnace shell.

[0017] Furthermore, in the furnace shell repair method, a device for monitoring the displacement change of the inner and outer furnace shells is provided on the outer furnace shell.

[0018] The beneficial effects of the present invention are:

[0019] Complete repair effect: By adding a new furnace shell outside the cracked furnace shell and welding it to the original furnace shell to form a new overall structure, the problems of repeated cracking of welds and cracking of parent materials in traditional repair methods are effectively solved. This repair method can more thoroughly solve the problem of furnace shell cracking and ensure the safe operation of the hot blast furnace.

[0020] Small impact on production: The repair method proposed in this scheme can be carried out while the hot blast furnace is online, without stopping the furnace, which greatly reduces the impact of the repair work on blast furnace production. At the same time, since the repair process is simple and fast, and the repair time is short, the risk of production interruption is further reduced.

[0021] Extend the service life of the furnace shell: By filling heat-conducting or anti-corrosion materials between the new and old furnace shells, installing corrugated compensators, and adopting equalizing pressure pipes and other measures, the temperature of the furnace shell is effectively reduced, and the impact of thermal stress and corrosive media on the furnace shell is reduced, thereby extending the service life of the furnace shell.

[0022] Improve economic benefits: Compared with traditional methods such as weld patching and overall replacement, this solution has low repair costs and saves investment. At the same time, due to the thorough repair effect, it reduces the downtime and maintenance costs caused by furnace shell cracking, and improves the overall economic benefits of the blast furnace.

[0023] Improve safety: This solution effectively improves the safety of the furnace shell by installing temperature monitoring devices, drainage facilities, measures to eliminate welding residual stress, and an outer protective layer. These measures can promptly detect and respond to abnormal conditions of the furnace shell and prevent accidents.

[0024] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 A schematic diagram of a method for repairing a furnace shell of a blast furnace top-fired hot blast furnace;

[0027] Figure 2 for Figure 1 A magnified view of region I;

[0028] Figure 3 for Figure 1 Magnified view of zone II;

[0029] Figure 4 for Figure 1 A-direction view.

[0030] Figure numerals: 1 - combustion chamber brick support 2 - burner brick support 3 - outer furnace shell 4 - original furnace shell 5 - gap between furnace shells 6 - heat conductive or anti-corrosion material 7 - corrugated compensator 8 - pressure equalizing pipe 9 - cold air valve 10 - cold air pipe 11 - thermometer 12 - drainage facility 13 - outer protective layer 14 - displacement measuring device. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0032] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0033] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] like Figure 1 to Figure 4 As shown, the present invention provides a method for repairing the furnace shell of a blast furnace top-fired hot blast furnace, which is particularly suitable for treating a furnace shell that is cracked during use. The method adds a layer of outer furnace shell 3 to the outside of the cracked furnace shell between the top-fired hot blast furnace burner brick support 1 and the combustion chamber brick support 2. The outer furnace shell 3 is spliced ​​into a whole in the circumferential direction and welded to the original furnace shell 4, which needs to meet the air pressure and gas sealing effect that the hot blast furnace is subjected to. A gap 5 is left between the new outer furnace shell 3 and the original furnace shell 4 to meet the air pressure and gas sealing effect that the hot blast furnace is subjected to.

[0035] The high temperature combustion area of ​​the top-fired hot blast furnace is located in the combustion chamber section between the burner and the regenerator. The acidic gas generated by the high temperature combustion condenses at the furnace shell, and under the action of wind pressure, the furnace shell will be subjected to tensile stress. Under the combined action of alternating tensile stress and acid corrosion, stress corrosion is formed, causing the furnace shell to crack. Therefore, this repair method is mainly suitable for the cracked furnace shell between the burner brick support 1 and the combustion chamber brick support 5 of the top-fired hot blast furnace.

[0036] There is air thermal resistance in the gap between the new and old furnace shells, which will cause the temperature of the inner furnace shell to rise. In order to improve the strength of the inner furnace shell, the method proposes to fill the gap 5 between the new outer furnace shell 3 and the original furnace shell 4 with heat-conducting or anti-corrosion materials 6, thereby reducing the temperature of the inner furnace shell or protecting the furnace shell.

[0037] There is a temperature difference between the inner and outer furnace shells, and the resulting thermal stress difference can easily pull apart the welding seam connecting the inner and outer furnace shells. The method proposes to set a corrugated compensator 7 on the outer furnace shell to absorb thermal displacement to release the thermal stress difference.

[0038] The repair method proposes to set a pressure equalizing pipe 8 on the outer furnace shell, and the pressure equalizing gas source gas intake point is on the cold air pipe 10 between the cold air valve 9 and the hot air furnace. In this way, during the hot air furnace supply period, the inner furnace shell offsets each other under the action of internal and external pressures, and the stress of the inner furnace shell will be greatly improved, which can reduce the further development of the inner furnace shell cracks.

[0039] The repair method proposes that a temperature monitoring thermometer 11 can be arranged on the inner and outer furnace shells to monitor the working status of the inner and outer furnace shells and set high and low temperature limit alarms.

[0040] Considering that the pressure-equalizing gas is prone to condensation under high pressure, the method proposes that a drainage facility 12 may be provided at the bottom of the outer furnace shell 3 so that workers can discharge the condensation water regularly.

[0041] The residual stress generated during furnace shell welding can easily lead to cracking of the furnace shell. Therefore, the repair method proposes that the on-site weld of the outer furnace shell 3 should be eliminated by measures such as annealing, vibration elimination, etc.

[0042] When the furnace shell temperature is lower than the acid dew point temperature of the combustion gas, the acidic medium will condense on the inner surface of the furnace shell and induce stress corrosion, which will cause the furnace shell to crack. In addition, extreme weather conditions, such as typhoons in coastal areas, may also cause drastic changes in the furnace shell temperature. In order to cope with these problems, the present repair method proposes to set an outer protective layer 13 on the outside of the outer furnace shell 3 to keep the temperature of the outer furnace shell 3 higher than the acid dew point temperature and reduce the impact of extreme weather on the furnace shell. This design effectively solves the common industry problem of stress corrosion cracking of the furnace shell.

[0043] In addition, in order to ensure that the working state of the inner furnace shell is effectively monitored, the repair method also proposes to set a device 14 for monitoring the displacement change of the inner and outer furnace shells on the outer furnace shell 3. The device can monitor the working state of the inner furnace shell in real time and issue an early warning when the inner furnace shell shows signs of failure, thereby ensuring the safe operation of the hot blast furnace.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for repairing the shell of a blast furnace top-fired hot blast furnace, characterized in that: An outer furnace shell (3) is welded to the outside of the original furnace shell (4) cracked between the top-burning hot blast furnace burner brick support (1) and the combustion chamber brick support (2); the outer furnace shell (3) is spliced ​​into a whole in the circumferential direction; a gap (5) is provided between the outer furnace shell (3) and the original furnace shell (4); the outer furnace shell (3) is used to withstand the hot blast furnace gas pressure and achieve gas sealing.

2. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: A heat-conducting or anti-corrosion material (6) is filled between the outer furnace shell (3) and the original furnace shell (4).

3. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: A corrugated compensator (7) for absorbing thermal displacement is arranged on the outer furnace shell (3).

4. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: The outer furnace shell (3) is provided with a pressure equalizing pipe (8) for pressure equalization, and the pressure equalizing gas source intake point is on the cold air pipe (10) between the cold air valve (9) and the hot air furnace.

5. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: Thermometers (11) for temperature monitoring are arranged on the outer furnace shell (3) and the original furnace shell (4).

6. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: A drainage facility (12) is provided at the bottom of the outer furnace shell (3).

7. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: The on-site welds of the outer furnace shell (3) are welded with measures to eliminate welding residual stress.

8. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: An outer protective layer (13) is arranged outside the outer furnace shell (3) to increase the temperature of the outer furnace shell (3) and prevent the furnace shell from being affected by extreme climate.

9. The method for repairing the shell of a blast furnace top-fired hot blast furnace according to claim 1, characterized in that: The outer furnace shell (3) is provided with a device (14) for monitoring the displacement change of the inner and outer furnace shells.

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