Long life maintenance method for a cast blast furnace hearth

Abstract

The application discloses a long-life maintenance method for a cast-in-place blast furnace hearth, which comprises the following steps: pouring grouting into grouting through holes to perform overall hearth pouring operation to form a hearth, and then baking the blast furnace; during the baking, the grouting through holes are kept open; after the baking of the blast furnace is completed, before the blast furnace is put into production, all the grouting through holes are closed; after the blast furnace is put into production, all the grouting through holes are opened in sequence to exhaust / liquid discharge, and then the grouting through holes are closed; before the next grouting through hole is opened, the previous grouting through hole is closed; the blast furnace is arranged to perform process idle blowing; during the idle blowing, the hearth is grouted through the grouting through holes; after the grouting operation is completed, all the grouting through holes are closed, and the blast furnace is put into production after being blown again. After the blast furnace is put into production, the hearth is still dried further, all the grouting through holes are opened in sequence to exhaust the water vapor generated in the drying process of the hearth, and the air holes of the hearth are reduced; during the idle blowing, the hearth is grouted to fill the gap between the hearth and the furnace shell.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and in particular to a long-life maintenance method for cast-in-place blast furnace hearths. Background Technology

[0002] In recent years, an integral cast-in-place hearth repair technology has attracted much attention in small and medium-sized blast furnaces in China. Because this hearth repair technology is quick and requires little investment, it is very popular among small and medium-sized blast furnaces.

[0003] However, due to the difference in material between the original carbon bricks and the castable refractory in the working layer of the sidewall of this type of cast-in-place blast furnace hearth, the cast-in-place material is prone to detaching from the carbon bricks during use. This creates large gaps between the cast-in-place material and the furnace shell, and between the cast-in-place material and the carbon bricks, leading to gas leakage. The gas trapped in these gaps, constantly compressing the cast-in-place hearth, will exacerbate hearth erosion and shorten its service life. Compared to traditional hearths constructed with ceramic cup carbon bricks, this type of integrally cast-in-place hearth has a shorter service life, especially under the conditions of high blast furnace strength, where the hearth's service life is only about 1.5 years, or even less. Currently, there is no relatively complete and efficient maintenance scheme for cast-in-place hearths, significantly reducing their cost-effectiveness and hindering the safe and stable operation of the blast furnace. Summary of the Invention

[0004] The purpose of this invention is to provide a long-life maintenance method for cast-in-place blast furnace hearths, which can effectively eliminate the gap between the cast-in-place hearth and the furnace shell, reduce the risk of gas leakage in the hearth area, and improve the service life of the cast-in-place hearth.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for long-life maintenance of cast-in-place blast furnace hearths is provided, comprising the following steps:

[0007] Step 100: Grouting through holes are provided in the gap between two adjacent cooling walls of the blast furnace. The grouting through holes penetrate the furnace shell. Multiple grouting through holes are provided at intervals along the circumference of the blast furnace. A grouting pipe is provided outside the blast furnace and is connected to the grouting through holes. A switch is provided on the grouting pipe.

[0008] Step 200: Grouting is injected into the grouting through hole to form the furnace hearth, and then the blast furnace is baked. During the baking process, the grouting through hole is kept open.

[0009] Step 300: After the blast furnace baking is completed and before the furnace is put into production, close all the grouting through holes;

[0010] Step 400: After the blast furnace is put into operation, all the grouting holes are opened in sequence for venting and / or draining liquid, and then the grouting hole is closed. Before opening the next grouting hole, the previous grouting hole is closed.

[0011] Step 500: Arrange for the blast furnace to undergo a process shutdown. During the shutdown, grout is applied to the hearth through the grouting holes. After the grouting operation is completed, all the grouting holes are closed, and the blast furnace is restarted and put into operation.

[0012] As a preferred method for long-life maintenance of cast-in-place blast furnace hearths, step 500 specifically comprises:

[0013] In the first month after the blast furnace is put into operation, the blast furnace is scheduled to undergo its first process shutdown, and the grouting pressure is P1.

[0014] In the second to 2.5 months after the blast furnace starts production, the blast furnace will be scheduled for a second process shutdown, with the grouting pressure being P2.

[0015] In the fourth to sixth month after the blast furnace starts production, the blast furnace is scheduled to undergo the third process shutdown, and the grouting pressure is P3.

[0016] Among them, P1 < P2 < P3.

[0017] As a preferred method for long-life maintenance of the hearth of a cast-in-place blast furnace, during the blast furnace restart operation, step 400 is performed every M4 time interval until no liquid is drained from the grouting hole.

[0018] As a preferred method for long-life maintenance of cast-in-place blast furnace hearths, M4 is one week.

[0019] As a preferred method for long-life maintenance of cast-in-place blast furnace hearths, P1 < P2 < P3 ≤ 10 kPa.

[0020] As a preferred method for long-life maintenance of cast-in-place blast furnace hearths, P1 = 2-4 kPa, P2 = 4-6 kPa, and P3 = 8-10 kPa.

[0021] As a preferred method for long-life maintenance of the hearth of a cast-in-place blast furnace, the interval between the execution of step 400 is M1 during the first week after the blast furnace is put into operation.

[0022] During the second week after the blast furnace starts production, the execution interval of step 400 is M2;

[0023] During the third week after the blast furnace starts production, the execution interval of step 400 is M3.

[0024] M2 < M1 ≤ M3;

[0025] During the fourth week after the blast furnace begins operation, the grouting through hole remains closed.

[0026] As a preferred method for long-life maintenance of cast-in-place blast furnace hearths, M1 is 24 hours, M2 is 8 hours, and M3 is 24 hours.

[0027] As a preferred embodiment of a long-life maintenance method for cast-in-place blast furnace hearths, the blast furnace includes multiple sets of cooling components, which are arranged at intervals in a vertical direction. Each set of cooling components includes multiple cooling walls arranged at intervals in a horizontal direction. A grouting hole group is provided in the gap between two adjacent sets of cooling components. The grouting hole group includes multiple grouting through holes, which are arranged at intervals in a horizontal direction within each set.

[0028] As a preferred method for long-term maintenance of cast-in-place blast furnace hearths, a grouting through hole is provided along the horizontal direction at intervals of 2.5 tuyeres or 3 tuyeres.

[0029] The beneficial effects of this invention are as follows: After the blast furnace is put into operation, the hearth will continue to dry. Opening all the grouting holes in sequence helps to remove the water vapor generated during the drying process of the hearth and reduce the porosity of the hearth. After a period of operation, the hearth is thoroughly dried. Due to the shrinkage of the hearth, a gap will be generated between the hearth and the furnace shell. At this time, the blast furnace is scheduled to be shut down for process operation. During the shutdown period, grouting is performed on the hearth to fill the gap between the hearth and the furnace shell, reduce the risk of gas leakage in the hearth area, and also improve the service life of the cast-in-place hearth. Attached Figure Description

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0031] Figure 1 This is a schematic diagram of the cast-in-place blast furnace cooling wall, tuyeres, and grouting through holes as described in an embodiment of the present invention.

[0032] In the picture:

[0033] 1. Cooling components; 11. Cooling wall; 2. Grouting hole group; 21. Grouting through hole; 3. Air outlet; 4. Iron tap. Detailed Implementation

[0034] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] like Figure 1 As shown, the present invention provides a long-life maintenance method for a cast-in-place blast furnace hearth, comprising the following steps:

[0037] Step 100: Grouting through holes 21 are provided in the gap between two adjacent cooling walls 11 of the blast furnace. Multiple grouting through holes 21 are provided at intervals along the circumference of the blast furnace. The grouting through holes 21 penetrate the furnace shell. A grouting pipe is provided outside the blast furnace and is connected to the grouting through holes 21. A switch is provided on the grouting pipe.

[0038] Step 200: Grouting is injected into the grouting through hole 21 to form the overall furnace hearth. Then the blast furnace is baked. During the baking process, the grouting through hole 21 remains open.

[0039] Step 300: After the blast furnace baking is completed and before the furnace is put into production, close all the grouting through holes 21;

[0040] Step 400: After the blast furnace is put into operation, open all the grouting holes 21 in sequence to vent / drain liquid, and then close the grouting hole 21. Before opening the next grouting hole 21, close the previous grouting hole 21.

[0041] Step 500: Arrange for the blast furnace to shut down. During the shutdown, grout the hearth through the grouting through hole 21. After the grouting operation is completed, close all the grouting through holes 21 and restart the blast furnace.

[0042] Understandably, the blast furnace baking temperature in step 200 is much lower than the temperature after the blast furnace is put into operation. Under normal circumstances, the baking temperature is only a few hundred degrees, while the temperature inside the blast furnace after it is put into operation can reach thousands of degrees. Because the temperature is low during the blast furnace baking, the hearth cannot be completely dried. Therefore, the hearth will continue to dry after the blast furnace is put into operation. At this time, opening all the grouting holes 21 in sequence is beneficial to venting the water vapor generated in the hearth during the drying process and reducing the porosity of the hearth. After a period of operation, the hearth is completely dried. Due to the shrinkage of the hearth, a gap will be generated between the hearth and the furnace shell. At this time, the blast furnace is arranged to shut down for process operation. During the shutdown period, grouting is performed on the hearth to fill the gap between the hearth and the furnace shell, reduce the risk of gas leakage in the hearth area, and also improve the service life of the cast-in-place hearth.

[0043] Furthermore, step 500 specifically includes:

[0044] In the first month after the blast furnace is put into operation, the blast furnace is scheduled for its first process shutdown, and the grouting pressure is P1.

[0045] In the second to 2.5 months after the blast furnace starts production, the blast furnace will be scheduled for its second process shutdown, with the grouting pressure being P2.

[0046] In the fourth to sixth month after the blast furnace starts production, the blast furnace is scheduled for its third process shutdown, and the grouting pressure is P3.

[0047] Among them, P1 < P2 < P3.

[0048] It is understandable that during the blast furnace restart phase after the first process shutdown, the newly filled grout will shrink during baking, and gaps will reappear between the hearth and the furnace shell. Therefore, grouting operations during the second and third process shutdowns can further fill the gaps between the hearth and the furnace shell. As the number of grouting operations during the process shutdowns increases, the gap between the hearth and the furnace shell gradually decreases, and the flow resistance of the grout in the gap between the hearth and the furnace shell increases. Setting P1 < P2 < P3 allows for improved filling effect by increasing the grouting pressure, thereby reducing the risk of gas leakage in the hearth area.

[0049] Furthermore, P1 < P2 < P3 ≤ 10 kPa, meaning that the grouting pressure needs to be no higher than 10 kPa. This can prevent the original furnace cylinder and furnace shell from being squeezed and deformed due to excessive grouting pressure.

[0050] Preferably, P1 = 2-4 kPa, P2 = 4-6 kPa, and P3 = 8-10 kPa. For example, P1 can be 2 kPa, 2.5 kPa, 3 kPa, 3.5 kPa, or 4 kPa; P2 can be 4 kPa, 4.5 kPa, 5 kPa, 5.5 kPa, or 6 kPa; and P3 can be 8 kPa, 8.5 kPa, 9 kPa, 9.5 kPa, or 10 kPa.

[0051] It should be noted that during the shutdown period, a high thermal conductivity material that is exactly the same as the material of the furnace hearth casting material reserved during the furnace hearth casting process should be used to grout the furnace hearth layer by layer from bottom to top.

[0052] Furthermore, during the blast furnace restart operation, step 400 is executed every M4 time interval until no liquid is drained from the grouting through hole 21. In this embodiment, the high temperature generated during the blast furnace restart operation will bake the newly filled grout. Water vapor will be generated during this stage. Executing step 400 at this stage can release the water vapor generated during the baking process in a timely manner, avoiding the formation of pores in the hearth.

[0053] Furthermore, during the first week after the blast furnace starts production, the interval for executing step 400 is M1.

[0054] During the second week after the blast furnace starts production, the execution interval for step 400 is M2;

[0055] During the third week after the blast furnace starts production, the execution interval for step 400 is M3.

[0056] M2 < M1 ≤ M3;

[0057] During the first four weeks after the blast furnace was put into operation, the grouting through hole 21 was kept closed.

[0058] Understandably, during the first week of blast furnace commissioning, the hearth slurry is still relatively moist. At this stage, the hearth is not stable and needs to be left to stand. Frequent opening of the grouting through-hole 21 is not conducive to the drying and shaping of the hearth. Moreover, a lot of water vapor is generated at this stage, and opening the grouting through-hole 21 to vent gas can easily bring out a large amount of gas, which is not conducive to production safety. In the second week of blast furnace commissioning, the hearth is drier. Increasing the frequency of venting at this stage helps to remove the water vapor generated by the hearth during high-temperature baking. In the third week of blast furnace commissioning, the hearth is further dried after the baking of the first two weeks. Reducing the frequency of venting at this stage can reduce the workload of workers. After three consecutive weeks of baking, in the fourth week of blast furnace commissioning, the blast furnace is basically dry, and there is basically no water vapor venting from the grouting through-hole 21. At this time, the grouting through-hole 21 can be kept closed.

[0059] Furthermore, M1 is 24 hours, M2 is 8 hours, M3 is 24 hours, and M4 is one week.

[0060] Furthermore, the blast furnace includes multiple sets of cooling components 1, which are arranged vertically at intervals. Each set of cooling components 1 includes multiple cooling walls 11 arranged horizontally at intervals. A grouting hole group 2 is provided in the gap between adjacent sets of cooling components 1. The grouting hole group 2 includes multiple grouting through holes 21, which are arranged horizontally at intervals within each group, meaning that the grouting through holes 21 within each group are on the same horizontal plane. This allows for uniform filling of the gap between the hearth and the furnace shell. An iron taphole 4 is also provided on the blast furnace.

[0061] Preferably, a grouting through hole 21 is provided at intervals of 2.5 air vents 3 or 3 air vents 3 along the horizontal direction.

[0062] In this embodiment, the grouting pipe has a diameter of 32mm and a length of approximately 25cm. The grouting pipe is connected to a grouting ball valve, which controls the flow of the grouting pipe. A plug is installed at the outer end of the grouting pipe. The grouting ball valve and the plug are equivalent to a switch on the grouting pipe.

[0063] Below is a 1200m 3 Examples of blast furnace specifications are provided below:

[0064] A steel plant 1200m 3 The blast furnace was repaired using an integral cast-in-place hearth repair technique. The blast furnace has a total of 20 tuyeres. The repair was carried out using the following steps:

[0065] a. Before the overall hearth casting operation of the blast furnace, a grouting through hole 21 is pre-installed between the gaps of the hearth cooling wall 11, at about 1 / 5 of the height of the lower part of the hearth, and at a distance of 2.5 tuyeres 3. 20 ÷ 2.5 = 8, a total of 8 grouting through holes 21 per layer; there are three layers of cooling wall 11 corresponding to the hearth, and 8 grouting through holes 21 are set in each layer. The height of the grouting through holes 21 in the same layer of cooling wall 11 is kept on the same plane;

[0066] b. A grouting pipe is welded to the outside of the grouting through hole 21. The grouting pipe has a diameter of 32mm and a length of about 25cm. The grouting pipe is connected to a grouting ball valve, which controls the passage of the grouting pipe. A plug is installed at the outer end of the grouting pipe.

[0067] c. After the blast furnace hearth casting operation is completed, during the blast furnace body baking period, open all the above-mentioned grouting through holes 21 grouting ball valves to keep them in the open state.

[0068] d. After the blast furnace body is dried and before it is put into operation, all the above-mentioned grouting holes 21 shall be closed.

[0069] e. When the blast furnace is put into operation, during the first week, the above-mentioned grouting holes 21 are opened one by one layer and one by one every day to discharge the water vapor and other liquids generated during the high-temperature baking of the hearth casting material. Then, the above-mentioned grouting holes 21 are closed one by one.

[0070] f. When the blast furnace is put into operation, in the second week, the above-mentioned grouting holes 21 are opened one by one every 8 hours to discharge the water vapor and other liquids generated during the high-temperature baking of the hearth casting material, and then the above-mentioned grouting holes 21 are closed one by one.

[0071] g. When the blast furnace is put into operation, in the third week, open the above-mentioned grouting through holes 21 one by one layer and one by one every day to discharge the water vapor and other liquids generated during the high-temperature baking of the hearth casting material, and then close the above-mentioned grouting through holes 21 one by one.

[0072] h. In the fourth week after the blast furnace was put into operation, there was basically no obvious liquid discharge from the reserved grouting through hole 21. Only the gas that was leaking between the furnace shell and the hearth of the cast body was discharged. All grouting through holes 21 were closed.

[0073] i. One month after the blast furnace is put into operation, the blast furnace will be scheduled for its first process shutdown of 6 hours to perform grouting treatment on the blast furnace hearth.

[0074] j. During the shutdown period, use the high thermal conductivity material that is exactly the same as the material of the hearth casting material reserved during the hearth casting. Grout the hearth layer by layer through the grouting holes 21 from bottom to top. The grouting pressure is controlled at 2-4 kPa. After the grouting operation is completed, close all grouting ball valves and plug them. After the blast furnace is restarted, remove the grouting pipe plugs after 5 days. Open the grouting ball valves once a week to drain the water vapor and other liquids generated during the hardening process of the grouting material until there is no obvious liquid discharged from the grouting pipe.

[0075] k. Starting from the start of blast furnace commissioning, a second process shutdown of 4 hours is carried out every 2 to 2.5 months. The hearth is grouted again through the reserved grouting through hole 21. The grouting pressure is controlled at 4 to 6 kPa. Then repeat step j until there is no obvious liquid discharge from the grouting pipe.

[0076] l. Starting from the start of blast furnace commissioning, the third process shutdown of 3 hours is carried out 4 to 6 months later. The hearth part is grouted for the third time through the reserved grouting through hole 21. The grouting pressure is controlled at 8 to 10 kPa. Then repeat step j until there is no obvious liquid discharge from the grouting pipe.

[0077] The sign of successful grouting is: after the last grouting is completed and one month later, use a gas alarm to check all grouting holes 21, and there is no obvious gas at the outlet.

[0078] In the description herein, it should be understood that the terms "upper," "lower," "left," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are used merely for descriptive distinction and have no special meaning.

[0079] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0080] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0081] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A method for long-life maintenance of a cast-in-place blast furnace hearth, characterized in that, Includes the following steps: Step 100: Grouting through holes are provided in the gap between two adjacent cooling walls of the blast furnace. The grouting through holes penetrate the furnace shell. Multiple grouting through holes are provided at intervals along the circumference of the blast furnace. A grouting pipe is provided outside the blast furnace and is connected to the grouting through holes. A switch is provided on the grouting pipe. Step 200: Grouting is injected into the grouting through hole to form the furnace hearth, and then the blast furnace is baked. During the baking process, the grouting through hole is kept open. Step 300: After the blast furnace baking is completed and before the furnace is put into production, close all the grouting through holes; Step 400: After the blast furnace is put into operation, all the grouting holes are opened in sequence for venting and / or draining liquid, and then the grouting hole is closed. Before opening the next grouting hole, the previous grouting hole is closed. Step 500: Arrange for the blast furnace to undergo a process shutdown. During the shutdown, grouting is performed on the hearth through the grouting through holes. In the first month after the blast furnace starts production, the blast furnace is scheduled for its first process shutdown, with a grouting pressure of P1. In the second to 2.5 months after the blast furnace starts production, the blast furnace is scheduled for its second process shutdown, with a grouting pressure of P2. In the fourth to sixth months after the blast furnace starts production, the blast furnace is scheduled for its third process shutdown, with a grouting pressure of P3, where P1 < P2 < P3. After the grouting operation is completed, all the grouting through holes are closed, and the blast furnace is restarted. During the restart of the blast furnace, step 400 is performed every M4 time interval until there is no more liquid draining from the grouting through holes. During the first week after the blast furnace starts production, the interval for executing step 400 is M1. During the second week after the blast furnace starts production, the execution interval of step 400 is M2; During the third week after the blast furnace starts production, the execution interval of step 400 is M3. M2 < M1 ≤ M3; During the fourth week after the blast furnace begins operation, the grouting through hole remains closed.

2. The long-life maintenance method for cast-in-place blast furnace hearths according to claim 1, characterized in that, M4 is for one week.

3. The long-life maintenance method for cast-in-place blast furnace hearths according to claim 1, characterized in that, P1 < P2 < P3 ≤ 10 kPa.

4. The long-life maintenance method for cast-in-place blast furnace hearths according to claim 3, characterized in that, P1=2~4kPa, P2=4~6kPa, P3=8~10kPa.

5. The long-life maintenance method for cast-in-place blast furnace hearths according to claim 1, characterized in that, M1 is 24 hours, M2 is 8 hours, and M3 is 24 hours.

6. The long-life maintenance method for cast-in-place blast furnace hearths according to claim 1, characterized in that, The blast furnace includes multiple sets of cooling components, which are arranged at intervals in the vertical direction. Each set of cooling components includes multiple cooling walls arranged at intervals in the horizontal direction. A grouting hole group is provided in the gap between two adjacent sets of cooling components. The grouting hole group includes multiple grouting through holes, which are arranged at intervals in the horizontal direction within each group.

7. The long-life maintenance method for cast-in-place blast furnace hearths according to claim 6, characterized in that, Along the horizontal direction, a grouting through hole is provided at a distance of 2.5 air vents or at a distance of 3 air vents.

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