Method for treating hearth congelation in medium repair of blast furnace

Abstract

The invention relates to a method for treating hearth congelation in medium repair of a blast furnace, which comprises the following steps of: after the blast furnace is shut down and before charging, burning oxygen from an iron notch until a certain space is formed, so that a tuyere and the iron notch are ventilated; a compressed air consumable steel pipe is inserted from the iron notch, and compressed air is introduced into the compressed air consumable steel pipe; loading materials; after charging and within the preset time before air supply, oxygen burning operation is conducted on the compressed air consumable steel pipe, and it is guaranteed that the tuyere and the iron notch are ventilated; and embedding an oxygen lance from the iron notch or plugging the iron notch by using anhydrous stemming, and carrying out blast furnace air supply production. The method is simple in process and convenient to operate. And the situation that in existing production, workers enter the furnace to conduct condensation cleaning operation is avoided, and the personal safety of the workers is guaranteed. In addition, furnace charge from the air outlet to the iron notch does not need to be scrabbed, and maintenance time is saved. And finally, the slag iron can rapidly permeate into the iron notch, and conditions are created for rapid reblowing production.

Description

Technical Field

[0001] The present invention relates to the field of repairing blast furnace production, and more particularly to a method for treating hearth condensates during medium repairs of blast furnaces. Background Art

[0002] During medium repairs of blast furnaces, the empty stockline method is usually adopted. The empty stockline method means that during the furnace shutdown process, no materials are charged. When the stock surface in the furnace drops, water is sprayed from the furnace top to control the furnace top temperature. When the stock surface drops below the tuyere plane, the blast is stopped. After the blast is stopped, slag and sprayed covering materials are pressed onto the stock surface to suppress the furnace temperature, and maintenance operations are carried out without tapping the hearth residual iron. After the maintenance is completed, usually only the rebounded materials sprayed on the furnace body, the pressed-in slag, the sprayed coating materials, and the coke on the stock surface can be removed. After the above-mentioned covering materials are dug out, due to the high temperature and gas in the hearth, the high-temperature coke and condensates in the area from the tuyere zone to the taphole cannot be cleaned, and the blast furnace is directly reblown. Since it is impossible to completely drain the slag and iron in the furnace before the blast furnace is stopped, and some coke burns to produce compounds during the blast stoppage period, a large amount of condensates exist between the coke in the hearth, and there are almost no pores between the tuyere and the taphole. When the furnace is blown in after startup, the generated slag and iron cannot normally penetrate to the taphole and be discharged outside the furnace in time. Therefore, it often affects the reblowing production of the blast furnace. Summary of the Invention

[0003] In view of the above-mentioned technical problems, a method for treating hearth condensates during medium repairs of blast furnaces is provided.

[0004] The technical means adopted by the present invention are as follows:

[0005] A method for treating hearth condensates during medium repairs of blast furnaces includes the following steps:

[0006] Within a preset time after the blast furnace is shut down and before charging, oxygen is blown from the taphole until a certain space is burned out to make the tuyere and the taphole permeable;

[0007] A compressed air consumable steel pipe is inserted into the taphole, and compressed air is introduced into the compressed air consumable steel pipe;

[0008] Charging;

[0009] Within a preset time after charging and before blowing, an oxygen blowing operation is performed on the compressed air consumable steel pipe to ensure that the tuyere and the taphole are permeable;

[0010] An oxygen lance is buried from the taphole or the taphole is blocked with anhydrous gunite, and the blast furnace is blown for production.

[0011] Further, the preset time after the blast furnace is shut down and before charging is specifically 48 hours before blowing.

[0012] Further, when blowing oxygen from the taphole within the preset time after the blast furnace is shut down and before charging, the oxygen supply pressure should be not less than 0.7 MPa.

[0013] Further, the steel pipe diameter of the compressed air consumable steel pipe is 60 - 80 mm, and it extends 2 - 2.5 m into the furnace. A number of through holes are opened at intervals of 20 ± 2 cm above the steel pipe extending into the furnace.

[0014] Further, the pressure of the compressed air introduced is not less than 0.5 MPa.

[0015] Further, after charging and before the preset time of air supply, specifically 12 hours before air supply.

[0016] Further, the method for monitoring the air permeability of the tuyere and the taphole is the visual method or by setting a sulfur dioxide monitoring device. When the detected sulfur dioxide concentration reaches the preset value, it is confirmed that the tuyere and the taphole are air permeable.

[0017] Compared with the prior art, the present invention has the following advantages: The process of the present invention is simple and the operation is convenient. It avoids the situation in the existing production where workers enter the furnace for condensation cleaning operations, ensuring the personal safety of the personnel. In addition, there is no need to remove the furnace burden in the section from the tuyere to the taphole, saving the maintenance time. Finally, the present invention is conducive to the rapid penetration of slag and iron to the taphole, creating conditions for rapid resumption of blast furnace production. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 For the prior art, it is a schematic diagram of the situation where the un-discharged slag and iron during the period from the blast furnace shutdown and blast suspension to the resumption of blast cause no pores in the section between the taphole and the tuyere.

[0020] Figure 2 It is a schematic diagram of burning oxygen to create a certain space.

[0021] Figure 3 It is a schematic diagram of the structure of the compressed air consumable steel pipe of the present invention.

[0022] Figure 4 It is a schematic diagram of introducing compressed air into the compressed air consumable steel pipe.

[0023] Figure 5 It is a schematic diagram of charging.

[0024] Figure 6 It is a schematic diagram of burning oxygen before air supply.

[0025] Figure 7Schematic diagram of inserting an oxygen lance from the taphole after burning out the space. Detailed implementation manners

[0026] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. The description of at least one exemplary embodiment below is actually only illustrative and in no way restricts the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that the terms used herein are only for describing the specific implementation manners and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless otherwise clearly specified in the context, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of the described features, steps, operations, devices, components and / or their combinations.

[0029] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as a part of the specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0030] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary statements, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present invention: the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0031] For the convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above-mentioned" etc. can be used here to describe the spatial positional relationship between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0032] In addition, it should be noted that using words such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without additional statements, the above words have no special meanings. Therefore, it should not be construed as a limitation on the protection scope of the present invention.

[0033] During the period from the blast furnace shutdown and blast cut-off to the resumption of blowing, some of the coke between the tuyeres and the iron notch in the hearth burns to produce compounds, as well as the slag and iron that were not completely discharged before the blast cut-off, resulting in no porosity between the iron notch and the tuyere area, such as Figure 1 Therefore, the embodiments of the present invention disclose a method for treating the hearth condensate during the medium repair of a blast furnace, including the following steps:

[0034] Within a preset time after the blast furnace shutdown and before charging, as Figure 2 shown, oxygen is blown from the iron notch until a certain space is burned out to make the tuyere and the iron notch breathable; as an optional implementation manner, in this step, three-stage oxygen supply control is adopted: Initial stage (0 - 2h): 0.7MPa, 30m 3 / min; Strengthening stage (2 - 4h): 1.0MPa, 50m 3 / min; Maintenance stage (4 - 6h): 0.8MPa, 40m 3 / min. During this stage, by configuring the infrared thermal imaging monitoring system, the real-time monitoring of the internal combustion temperature is ensured. The temperature gradient change is monitored in real time to ensure that the local temperature ≥ 1250 °C.

[0035] Insert from the iron notch as Figure 3 shown in the compressed air consumable steel pipe. Compressed air is introduced into the compressed air consumable steel pipe, as Figure 4 shown, to ensure the burned-out voids;

[0036] After burning out the voids, charge the material;

[0037] Since after charging, the pressure of the burden column increases, the burden in the iron notch area is compacted, and the previously burned-out space becomes smaller, as Figure 5 shown. Therefore, after charging and within the preset time before blowing, an oxygen-burning operation is performed on the compressed air consumable steel pipe to ensure the air permeability between the tuyere and the iron notch, as Figure 6 shown; As an optional implementation manner, in this step, a pulse oxygen supply mode (5 - 8 min pulse period) is adopted. As a safety protection countermeasure, the compressed air pipeline is also connected with a nitrogen emergency purge system, and when an emergency occurs in the furnace, the switching of the blown-in gas is carried out.

[0038] As Figure 7 shown, insert an oxygen lance from the iron notch or plug the iron notch with anhydrous gun clay to carry out blast furnace blowing production.

[0039] Furthermore, the preset time after the blast furnace is shut down and before charging is specifically 48 hours before blowing.

[0040] Furthermore, within the preset time after the blast furnace is shut down and before charging, the oxygen supply pressure for oxygen-burning from the iron notch should be not less than 0.7 MPa.

[0041] Furthermore, the steel pipe diameter of the compressed air consumable steel pipe is 60 - 80 mm, it penetrates 2 - 2.5 m into the furnace, and several through holes are opened at intervals of 20 ± 2 cm above the steel pipe penetrating into the furnace.

[0042] In this embodiment, the adopted compressed air consumable steel pipe is a conventional steel pipe, which is used as a consumable during the heating process. By the way of replenishing section by section, it is ensured that the compressed air can be normally injected during this stage. It should be noted that even if the consumable steel pipe with different chemical components from that in the furnace is melted during this stage, due to its small addition amount, it will not affect the furnace internal components.

[0043] As another optional implementation manner, when it can ensure that the above local temperature ≥ 1250 °C, a heat-resistant steel pipe, such as Cr25Ni20 steel pipe, can also be adopted, which is always inserted into the iron notch and the injection of compressed air is ensured. In this case, a conical head is arranged at the end of the heat-resistant steel pipe to ensure the convenience of inserting into the burden.

[0044] Furthermore, the pressure of the compressed air introduced is not less than 0.5 MPa.

[0045] Furthermore, within a preset time after charging and before air supply, specifically 12 hours before air supply.

[0046] Furthermore, the method for monitoring the air permeability of the tuyere and the taphole is visual inspection or by setting up a sulfur dioxide monitoring device. When the detected sulfur dioxide concentration reaches the preset value, it is confirmed that the tuyere and the taphole are air permeable.

[0047] As the simplest method, it is visual inspection. When yellow smoke appears, it ensures the air permeability of the tuyere and the taphole. However, this method has risks and uncertainties.

[0048] As other alternative embodiments, a high-temperature pressure sensor can also be installed 1.5 m inside the taphole. Select two adjacent tuyeres and install pressure transmitters at their branch pipes, connecting the taphole and the tuyere measuring points to display accurate differential pressure data.

[0049] This method is based on the principles of thermodynamic expansion and gas dynamics theory. Through a process combining segmented oxidation combustion and forced convection, a stable gas flow path penetrating the hearth is established. Adopting an oxygen-air alternating operation mode, layer-by-layer peeling and melting conversion of condensates are realized, ensuring the reconstruction of the hearth activity after the blast furnace resumes blowing.

[0050] This method is applied during the intermediate repair of the new No. 2 blast furnace in the Beiying Ironmaking Plant of Benxi Steel. It is not necessary to remove the burden in the hearth, shortening the repair period by 3 days. Moreover, the slag and iron produced after the blast furnace resumes blowing quickly penetrate to the taphole, creating favorable conditions for rapid resumption of production. The blast furnace reaches its production capacity 4 days earlier, creating significant economic benefits.

[0051] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating condensate in a blast furnace during repair, characterized in that: The steps include: During the preset time after the blast furnace is shut down and before charging, oxygen is burned from the taphole until a certain space is burned out to make the tuyere and taphole breathable; Insert the compressed air consumable steel pipe from the iron mouth, and let the compressed air into the compressed air consumable steel pipe; Loading; After loading and before air supply, oxygen is burned on the compressed air consumable steel pipe within the preset time to ensure air permeability of the air outlet and the iron mouth; The oxygen lance is buried in the taphole or the taphole is blocked with anhydrous clay to carry out blast furnace air supply production.

2. The method according to claim 1, characterized in that The preset time after the blast furnace is shut down and before charging is specifically 48 hours before air supply.

3. The method according to claim 1, characterized in that During the preset time after the blast furnace is shut down and before charging, the oxygen supply pressure from the taphole must be no less than 0.7MPa.

4. The method according to claim 1, characterized in that The steel pipe of the compressed air consumable material has a diameter of 60-80 mm and is inserted 2-2.5 m into the furnace. A plurality of through holes are provided above the steel pipe inserted into the furnace at intervals of 20±2 cm.

5. The method according to claim 1, characterized in that The pressure of the compressed air introduced shall not be less than 0.5MPa.

6. The method according to claim 1, characterized in that After loading, within the preset time before air supply, specifically 12 hours before air supply.

7. The method according to claim 1, characterized in that The method for monitoring the air permeability of the tuyere and the tapping hole is visual inspection or by setting up a sulfur dioxide monitoring device. When the sulfur dioxide concentration is detected to reach a preset value, it is confirmed that the tuyere and the tapping hole are permeable.

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