An operation method for coping with the change of furnace profile after the start-up of a large blast furnace

Abstract

The present application relates to the technical field of blast furnace ironmaking, and specifically discloses an operation method for coping with furnace profile conversion after a large blast furnace is started up, which comprises the following steps: determining the start of the furnace profile conversion process: 10-50 days after the large blast furnace is started up, determining that the furnace profile conversion is needed according to the temperature change of the outer wall of the blast furnace; setting a burden distribution system for the furnace profile conversion period; periodically implementing the burden distribution system for the furnace profile conversion period; controlling the temperature of the molten iron and the content of Si element during the furnace profile conversion period; the operation duration of the furnace profile conversion period: the burden distribution system for the furnace profile conversion is implemented for 3-5 days as a treatment cycle, and the interval is one week; determining whether the furnace profile conversion process is completed according to step S1, and if not, another operation cycle is implemented; after the furnace profile conversion process is completed, the normal operation system is restored; and the present application maximally avoids the fluctuation of the blast furnace condition and reduces the risk of the deterioration of the economic and technical indexes of the blast furnace during the furnace profile conversion period.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and specifically to an operational method for handling furnace type conversion after the start-up of a large blast furnace. Background Technology

[0002] A large blast furnace refers to a blast furnace with an effective volume of not less than 4800 m³. 3 The blast furnace. Before starting a large blast furnace during a mid-term or major overhaul, a 50-150mm thick coating is sprayed onto the inside of the furnace walls. This coating serves four main purposes:

[0003] First, a protective working lining is formed. A layer of refractory material is sprayed onto the surface of the constructed permanent brick lining, serving as the initial "working surface" after the blast furnace is started. This sprayed material can directly withstand the impact and abrasion of the furnace charge in the early stages of start-up, as well as the scouring of the high-temperature airflow, effectively protecting the expensive and precisely constructed permanent brick lining from physical damage and chemical erosion.

[0004] Secondly, it enables the rapid establishment of a reasonable furnace configuration. The rough surface created by spraying helps the furnace charge (especially coke) to adhere and accumulate better during startup, thus forming a furnace configuration that meets smelting requirements more quickly and systematically, and shortening the furnace condition adjustment period after startup.

[0005] Thirdly, it seals brick joints and smooths the surface. Spraying can effectively fill the brick joints left during the construction of permanent brick linings, seal any possible tiny air gaps, and reduce damage to cooling equipment and the furnace shell caused by high-temperature gas leakage after start-up. At the same time, it can smooth the surface of the brick lining, reduce unevenness, and facilitate the uniform descent of furnace charge and the rational distribution of gas flow.

[0006] Fourth, it regulates the thermal state inside the furnace. The spray coating has certain heat insulation and heat storage properties, which helps to evenly and gradually increase the furnace wall temperature during the start-up and baking stage, reduce thermal stress inside the brick lining, and prevent cracks in the refractory material. It can also play a certain role in heat preservation after the blast furnace is started.

[0007] In the initial stage of blast furnace start-up, the sprayed coating forms a very regular furnace shape, and start-up is generally smooth. After 10-50 days of blast furnace start-up, the sprayed coating gradually wears off and detaches, transforming the furnace into a new operating shape. The detachment time is closely related to the coating thickness, coating quality, and spraying application quality. During the furnace shape transformation process, because the coating begins to detach locally, the operating furnace shape gradually becomes irregular from the initial irregular shape, causing fluctuations in blast furnace conditions. Maintaining continuous and stable operation during the furnace shape transformation after blast furnace start-up is crucial, making the operational handling during this process particularly important. Errors in handling the furnace shape transformation can generally affect the blast furnace's economic and technical indicators for 2-4 months, especially production indicators, resulting in significant overall economic losses. Currently, there is no comprehensive operational method in the industry to handle the furnace shape transformation. Therefore, it is necessary to explore an operational method to address the insufficient stability of furnace operation during the furnace shape transformation period after the start-up of large blast furnaces. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of this invention is to provide an operation method for changing the furnace type after the start-up of a large blast furnace.

[0009] The technical solution adopted by this invention to solve its technical problem is: an operation method for dealing with the furnace type conversion after the start-up of a large blast furnace, comprising the following steps:

[0010] S1. Determine the start of the furnace type conversion process: 10-50 days after the large blast furnace is started, determine the start of the furnace type conversion based on the temperature change of the outer wall of the blast furnace;

[0011] S2. Set the material distribution system during the furnace type conversion period;

[0012] S3, the material distribution system is carried out during the furnace type conversion period;

[0013] S4. Control the temperature of molten iron and the content of Si element during the furnace type conversion period;

[0014] S5. Duration of furnace type conversion operation: The furnace type conversion operation cycle is 3-5 days, with an interval of one week.

[0015] S6. Determine whether the furnace type conversion process is complete based on step S1. If not, perform another operation cycle.

[0016] S7. After the furnace type conversion process is completed, normal operating procedures shall be restored.

[0017] Specifically, in step S1, the outer wall of the blast furnace is the cooling wall of the furnace belly and the furnace waist. The temperature of the cooling wall of the furnace belly and the furnace waist shows a local abnormal increase, and then quickly decreases to the average level.

[0018] Specifically, the furnace type conversion period feeding system in step S2 includes: 5-10 tons of additional coke, including 2-6 tons of coke fed into the outermost ring at the normal coke feeding angle and 2-4 tons of coke fed into the center at 11°; the additional coke and the normal load coke are fed into the furnace at the same time, with ≥3 feeding rings, of which the edge coke has ≥1 feeding ring and the center coke has ≥2 feeding rings.

[0019] Specifically, in step S3, the material feeding cycle is to add a separate operating furnace type to change the material feeding system after 5-10 batches of normal material feeding, and repeat this cycle.

[0020] Specifically, in step S4, the temperature of the molten iron is ≥1510℃, and the mass percentage of Si in the molten iron is ≥0.4%.

[0021] Specifically, the operation cycle in step S6 shall be performed continuously for no more than 3 times.

[0022] Specifically, if the operation cycle is repeated for 3 consecutive times and the furnace type conversion is still not completed, the normal operating procedure will be adjusted and the furnace type conversion operation will no longer be carried out.

[0023] The present invention has the following beneficial effects:

[0024] This invention presents a method for handling furnace type transitions after the start-up of large blast furnaces. Without altering the original charging system, it periodically adds a special charging system for the transition period. This transition charging system develops edge airflow, strengthens the scouring of the sprayed coating, and shortens the transition time. Furthermore, it guides the central airflow by adding coke to the center, ensuring smooth furnace operation. This invention, by adding coke without changing the original charging system, ensures that quality accidents such as excessively low furnace temperature or extra-strength iron will not occur during operation. It does not change the furnace charge structure and charging system during normal production, minimizing fluctuations in blast furnace conditions and reducing the risk of deterioration in the blast furnace's economic and technical indicators during the transition period. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] Example: at 5100m 3 Taking a blast furnace as an example:

[0027] The charging matrix after blast furnace overhaul and restart is as follows: .

[0028] The 1st to 6th gears correspond to fabric chute angles of 42°, 40°, 37.5°, 35°, 32°, and 29.5°, respectively.

[0029] Before blast furnace start-up, the interior wall coating was thin-walled, with an average thickness of 50mm. One week after start-up, temperature fluctuations began to appear on the cooling wall of the furnace waist, with local temperatures suddenly rising from the normal 46.4℃ to over 85℃. Based on this, it was determined that the blast furnace type conversion had begun after start-up.

[0030] The blast furnace has begun implementing procedures to address the furnace type conversion after start-up. The specific procedures are as follows:

[0031] (1) Add a material distribution system during the furnace type conversion period.

[0032] The feeding system during the furnace type conversion period includes: 6 tons of additional coke, which is fed into the furnace together with the original normal coke;

[0033] Mineral distribution matrix Without changing the focus matrix, adjust it as follows: .

[0034] The 1st to 7th gears correspond to fabric chute angles of 42°, 40°, 37.5°, 35°, 32°, 29.5°, and 11°, respectively. Each rotation corresponds to 2 tons of fabric coke.

[0035] The cobalt matrix is ​​set to level 1 (corresponding to 42°), with 4 outermost cobalt rings, weighing 8 tons, including 2 tons of additional cobalt. The center cobalt matrix is ​​set to level 7 (corresponding to 11°), with 2 cobalt rings, weighing 4 tons. The total additional cobalt is 6 tons.

[0036] (2) The material distribution system is carried out periodically during the furnace type conversion period.

[0037] The process involves changing the material supply using a separate operating furnace after every 5 normal batches of material feeding, and repeating this cycle. That is, every 6 batches constitute one group, and one cycle is completed. (This is repeated 5 times.) +1 The mineral distribution matrix remains unchanged.

[0038] (3) During the furnace type conversion period, the fuel ratio is controlled at 2-4 kg / t, the molten iron temperature is ≥1510℃, and [Si] is ≥0.4%.

[0039] (4) Duration of furnace type conversion operation.

[0040] After operating the furnace type conversion material system for 4 days, pause for 7 days and revert to the original material distribution matrix. .

[0041] (5) After a 7-day suspension, the temperature of the 9th cooling wall still rose suddenly, so the furnace type conversion period operation was carried out again.

[0042] (6) After two operating cycles, the overall temperature of the nine cooling walls increased compared to before, with the average temperature remaining at 48.3℃. The Al2O3 content in the blast furnace slag decreased from 16.51% initially to 15.47%. Based on the comprehensive judgment, the furnace type conversion was completed and the original charging matrix was restored.

[0043] An operational method for handling furnace type conversion after the start-up of a large blast furnace, which does not change the original blast furnace charging system during the execution process, and stabilizes the blast furnace condition to the greatest extent.

[0044] The furnace type conversion period charging system adopted in this invention is carried out at intervals, which avoids the abnormal flow of gas from the edge and center of the blast furnace.

[0045] This invention uses additional coke to provide the heat required to wash away the coating paint from the furnace wall, thus avoiding drastic fluctuations in blast furnace temperature or quality accidents such as extra-scale iron production.

[0046] This method involves a comprehensive assessment of the furnace condition at the end of each processing cycle to ensure precise control over the duration of the operation.

[0047] This method adds at least 3 rings of coke feeding into the furnace, ensuring the circumferential uniformity of the charge distribution, preventing excessive development or suppression of local airflow, ensuring the uniformity of the airflow scouring the circumferential furnace wall coating, promoting the uniform transition of furnace type, and ensuring the stable operation of the blast furnace during the transition period.

[0048] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0049] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for handling furnace type conversion after start-up of a large blast furnace, characterized in that, Includes the following steps: S1. Determine the start of the furnace type conversion process: 10-50 days after the large blast furnace is started, determine the start of the furnace type conversion based on the temperature change of the outer wall of the blast furnace; S2. Set the material distribution system during the furnace type conversion period; S3, the material distribution system is carried out during the furnace type conversion period; S4. Control the temperature of molten iron and the content of Si element during the furnace type conversion period; S5. Duration of furnace type conversion operation: The furnace type conversion operation cycle is 3-5 days, with an interval of one week. S6. Determine whether the furnace type conversion process is complete based on step S1. If not, perform another operation cycle. S7. After the furnace type conversion process is completed, normal operating procedures shall be restored.

2. The method for handling furnace type conversion after start-up of a large blast furnace according to claim 1, characterized in that, In step S1, the outer wall of the blast furnace is the cooling wall of the furnace belly and waist. The temperature of the cooling wall of the furnace belly and waist shows a local abnormal increase, and then quickly decreases to the average level.

3. The method for handling furnace type conversion after start-up of a large blast furnace according to claim 1, characterized in that, The furnace type conversion period feeding system in step S2 includes: 5-10 tons of additional coke, including 2-6 tons of coke fed into the outermost ring at the normal coke feeding angle and 2-4 tons of coke fed into the center at 11°; the additional coke and the normal load coke are fed into the furnace at the same time, with ≥3 feeding rings, of which the edge coke has ≥1 feeding ring and the center coke has ≥2 feeding rings.

4. The method for handling furnace type conversion after start-up of a large blast furnace according to claim 1, characterized in that, The material feeding cycle in step S3 involves adding a separate operating furnace type to change the material feeding system after every 5-10 batches of normal material feeding, and repeating this cycle.

5. The method for handling furnace type conversion after start-up of a large blast furnace according to claim 1, characterized in that, In step S4, the temperature of the molten iron is ≥1510℃, and the mass percentage of Si in the molten iron is ≥0.4%.

6. The method for handling furnace type conversion after start-up of a large blast furnace according to claim 1, characterized in that, The operation cycle in step S6 shall not be performed continuously for more than 3 times.

7. The method for handling furnace type conversion after start-up of a large blast furnace according to claim 6, characterized in that, If the furnace type conversion is not completed after three consecutive operation cycles, the normal operating procedure will be adjusted, and the furnace type conversion operation will no longer be performed.