Blast furnace shutdown method without furnace washing operation

Abstract

The invention discloses a blast furnace blowing-out method without furnace washing operation, which comprises the following steps: (1) preparation before blowing-out: keeping the furnace condition stable and smooth, keeping the temperature of molten iron higher than 1510 DEG C, and keeping the content of S in the molten iron to be 0.03-0.04%; (2) blowing out the blast furnace: (1) after the pre-damping down is finished, adding two batches of coke into the blast furnace, stopping feeding, blowing air to lower the charge level, and controlling the temperature of furnace top gas to be 250-350 DEG C by adopting a furnace top water-fetching cooling process; (2) blowing air for 1.0-1.5 hours, tapping for the first time, and blocking an iron notch when air comes from the iron notch; meanwhile, the furnace top gas temperature is controlled to be 250-350 DEG C by adopting a furnace top water-fetching cooling process and a method for gradually reducing the air supply flow; (3) when CO in the coal gas is reduced to 30% or below and CO2 is increased to 6.5% or above, secondary tapping is carried out, and the iron notch is blocked when wind comes from the iron notch; (4) when N2 in the furnace top gas rises to 60% or above, the charge level enters a tuyere area, iron is discharged for the third time, and the iron notch is blocked when wind comes from the iron notch; and (5) after the third tapping is finished, remaining coke and blowing out the furnace, changing the blast furnace to normal pressure operation, switching gas for damping down, and finishing the blowing out operation of the blast furnace, wherein the whole blowing out process takes 8-10 hours.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy saving and consumption reduction in steel smelting, in particular to a blast furnace shutdown method without furnace washing operation. The method can save the cost of furnace washing material during blast furnace shutdown and save the cost of covering coke, and the covering coke of the present blast is used for the production of the next blast furnace. BACKGROUND

[0002] Blast furnace shutdown is an important link of blast furnace ironmaking production, which involves coal gas safety, equipment protection, environmental pollution control and other aspects. It plays a very important role in time, economy, technology and continuity with maintenance.

[0003] The existing blast furnace mainly relies on the method of washing the furnace before shutdown to reduce the adhesion of the furnace wall, improve the flowability of slag and iron, and activate the hearth. One week before shutdown, the angle of coal and ore distribution is adjusted, and the edge is moderately developed to flush the furnace wall. Two days before shutdown, the coal ratio is reduced for smelting; in terms of batching system, a small amount of washing material is added to each batch to reduce the slag basicity and improve the flowability of slag and iron. The defects of the existing shutdown technology are that washing increases the input cost and time cost of washing material.

[0004] The requirements for blast furnace shutdown are: first, to ensure safety and avoid personal and equipment accidents; second, to facilitate the removal and repair after shutdown; and third, to shorten the shutdown time as much as possible. There are two methods of shutdown, filling shutdown method (using gravel or medium-sized coke as filling material during shutdown) and empty line top water injection method. The empty line top water injection shutdown method is divided into diffusion method and coal gas recovery method.

[0005] At present, the empty line top water injection shutdown method of blast furnace is the mainstream, and most blast furnaces perform washing before shutdown, i.e. hot washing with washing material. Xinyu Iron and Steel Group Co., Ltd. (hereinafter referred to as Xinyu Steel) No. 9 and No. 10 blast furnaces successively lowered the material level and shut down on April 8, 2021 and November 15, 2021, respectively. Four days before shutdown, a certain amount of manganese ore was added for washing, and the Mn content in iron increased from 0.3% to about 0.6%, and the flowability of molten iron was improved (reference: Qian Kun, Li Weihua, Ma Xiwu. Xinyu 2500m³ blast furnace shutdown and residual iron production practice [J]. Jiangxi Metallurgy, 2023). The No. 2 blast furnace of E'gang (the applicant) was shut down for intermediate repair on December 15, 2023, and from December 1, 2023, serpentine was added for washing, consuming a total of 818 tons of serpentine. The cost of washing material consumed in the above-mentioned shutdown method is 160-200 thousand yuan.

[0006] From the above content, it can be seen that the washing operation of the blast furnace consumes a large amount of resources and occupies a large amount of time and labor cost. Therefore, how to achieve the shutdown of the blast furnace without washing operation requires new technical support. SUMMARY

[0007] The purpose of the present application is to provide a blast furnace stopping method without washing operation, under the premise of controlling the temperature of the top gas of the blast furnace at 250-350 DEG C by increasing the air volume, water cooling and other measures, ensuring the smooth tapping of the blast furnace and the safety of the furnace condition before the blast furnace is stopped; the method of the present application can cancel the washing of the blast furnace with washing materials on the basis of the method of washing the blast furnace with washing materials before the blast furnace is stopped, saving the cost investment of washing materials and the time cost of washing consumption.

[0008] The blast furnace stopping method without washing operation of the present application comprises the following steps:

[0009] (1) Preparation before stopping: keeping the furnace condition stable and smooth before stopping, ensuring the temperature of the molten iron > 1510 DEG C, and the mass percentage of sulfur in the molten iron being 0.03-0.04%;

[0010] (2) Blast furnace stopping step:

[0011] ① Pre-blowing operation is performed, after the pre-blowing is finished, 2 batches of coke, 20-25 t in total, are added into the blast furnace, the charging is stopped, the blast furnace starts to blow and lower the material level, the cold air flow is controlled at 4400-4500 m 3 / min, the oxygen flow is controlled at 50-80 m 3 / min, and the water cooling process is used to control the temperature of the top gas of the blast furnace to be stable at 250-350 DEG C;

[0012] ② The blast is blown for 1.0-1.5 h, the first tapping is started, and the iron notch is blocked when the air comes in; during the process of blowing and lowering the material level, the temperature of the top gas of the blast furnace is increased, the temperature of the top gas of the blast furnace is controlled to be not more than 350 DEG C, the water cooling process and the method of gradually reducing the blast flow are used to control the temperature of the top gas of the blast furnace to be stable at 250-350 DEG C, the cold air flow is gradually reduced to 3000-3500 m 3 / min, and the oxygen flow is gradually closed;

[0013] ③ When the CO in the top gas of the blast furnace is reduced to below 30%, the CO2 is increased to above 6.5%, the second tapping is started, and the iron notch is blocked when the air comes in;

[0014] ④ When the N2 in the top gas of the blast furnace is increased to above 60%, the material level enters the tuyere area, the third tapping is started, and the iron notch is blocked when the air comes in;

[0015] ⑤ After the third tapping is finished, the coke is left to directly stop the blast furnace, the blast furnace is changed to normal pressure operation, the top gas diffuser valve is opened, the gas is cut off and blown, the water cooling is performed, the stopping operation of the blast furnace is completed, and the temperature of the molten iron of the blast furnace is stable at 1480 DEG C-1505 DEG C during the whole stopping process, and the time consumption is 8-10 h.

[0016] Further, the furnace top water cooling process of step (2) first step is realized by a furnace top atomizing water spraying system, the furnace top atomizing water spraying system is realized by 16 water spraying guns surrounding the furnace top, a furnace top gas temperature detector and a PLC control system, when the 16 water spraying guns are fully opened, the opening degree of the furnace top atomizing water spraying system is 100%, each closed water spraying gun, the opening degree of the furnace top atomizing water spraying system is reduced by 6.25%, when two or more water spraying guns are closed, the center symmetry principle is closed, when the furnace top gas temperature is greater than 350 DEG C, the opening degree of the furnace top atomizing water spraying system is 100%, when the furnace top gas temperature is between 250 DEG C and 350 DEG C, the opening degree of the furnace top atomizing water spraying system is 50-100%, when the furnace top gas temperature is less than 250 DEG C, the opening degree of the furnace top atomizing water spraying system is less than 50%.

[0017] Further, the furnace top water cooling process of step (2) second step, when the furnace top gas temperature is greater than or equal to 250 DEG C, the opening degree of the furnace top atomizing water spraying system is 50-100%, when the furnace top gas temperature is less than 250 DEG C, the opening degree of the furnace top atomizing water spraying system is less than 50%.

[0018] The blast furnace in the application is 1800m 3 The blast furnace.

[0019] The application is made after the inventor deeply studies the principle of the blast furnace empty stock line furnace top water cooling blowdown method, compared with the prior art, the application points of the application are as follows:

[0020] (1) before the blast furnace is ready to be blown down, no washing material is added, the molten iron temperature is ensured to be above 1510 DEG C, the molten iron S content is ensured to be 0.3-0.4%, the purpose of reducing the adhering material on the furnace wall and the condensed iron layer in the furnace hearth is achieved, and the purpose of active furnace hearth is achieved;

[0021] (2) after the blast furnace pre-blowing is finished, 20-25t of coke (topping coke) is added into the blast furnace in two batches, the preparation for the blast furnace blowdown after iron tapping is made, after three times of iron tapping are completed, the distance between the topping coke and the center line of the tuyere is less than 1.5m, that is, the ratio of the volume of the coke to the cross-sectional area of the furnace hearth is less than 1.5, so that the coke (20-25t of topping coke) can be directly opened without waiting for the coke to be burned out, the blast furnace top diffuser valve is opened, the gas is cut off and the normal pressure operation is changed to blow down, the coke (20-25t of topping coke) can be dug out after the blast furnace is blown down and used for the next blast furnace production, and the coke cost is saved (in the conventional blowdown method, the topping coke needs to be burned out before the blast furnace is blown down);

[0022] (3) the blast furnace top atomizing water spraying system is used, the amount of cold air and oxygen is sent, and the temperature of the blast furnace top gas is controlled, so that the temperature of the blast furnace top gas is controlled at 250-350 DEG C, the purpose of avoiding the explosion during the blowdown process is achieved, and the safe blowdown of the blast furnace is ensured;

[0023] (4) without adding additional washing material, saving 160-200 washing material costs for each blast furnace shutdown, while saving a large amount of time cost and labor cost, using the method of the application to stop the blast furnace, only 8-10 hours can be safely stopped, which can save about 192-240 total production costs;

[0024] (5) using the method of the application to stop the blast furnace, the iron temperature during the shutdown process is stable at 1480-1505℃, the residual iron amount in the blast furnace hearth after shutdown is small, and the furnace wall is clean, meeting the requirements after conventional blast furnace shutdown.

[0025] The beneficial effects of the application are as follows:

[0026] (1) The application is a method for stopping a blast furnace without washing operation, compared with the prior art of adding washing material before shutdown, the washing material is cancelled, and the washing material cost, time cost and labor cost of traditional blast furnace shutdown are saved.

[0027] (2) The application uses a water cooling process on the top of the furnace and a blast volume control process to jointly control the top gas temperature and the gas value, which can avoid the occurrence of explosion during the shutdown process and ensure safe and rapid shutdown.

[0028] (3) The method of the application uses a coking operation to stop the furnace, which can save the cost of the cover coke during shutdown, and the cover coke of the current furnace is used for production in the next furnace, further reducing the production cost.

[0029] (4) Using the method of the application to stop the furnace, the iron temperature during the shutdown process is stable at 1480-1505℃, the residual iron amount in the blast furnace hearth after shutdown is small, and the furnace wall is clean, meeting the requirements of conventional blast furnace shutdown and repair, having good economic benefits, and meeting the requirements of green production. DETAILED DESCRIPTION

[0030] In order to better explain the technical scheme of the application, the technical scheme of the application will be further described below in combination with specific examples, and the following examples are only exemplary descriptions of the technical scheme of the application and do not limit the application in any form. The serial numbers of the following examples are only for description, not representing the advantages and disadvantages of the examples.

[0031] Example 1

[0032] This example takes the method of stopping the blast furnace without washing operation of the application implemented by No. 1 blast furnace of E'gang on December 15, 2024 as an example to explain the method of the application in detail. The effective volume of No. 1 blast furnace of E'gang is 1800m 3 .

[0033] The method of stopping the blast furnace without washing operation of the application comprises the following steps:

[0034] (1) Preparation before stopping blast furnace: high load of blast furnace is reduced from 0 o'clock on December 15, 2024, stable furnace condition is kept before stopping blast furnace, to ensure that the temperature of molten iron is 1525℃, and the mass percentage of sulfur in molten iron is increased to 0.037%;

[0035] (2) Stopping blast furnace steps:

[0036] ① Pre-blowing operation is carried out, after pre-blowing is finished, 2 batches of coke are added into blast furnace, total 23t, stopping charging at 12:38 on December 15, blast furnace starts to blow and to reduce material level, cold air flow is controlled at 4400-4500m 3 / min, oxygen flow is controlled at 50-70m 3 / min, at the same time, water cooling process of blast furnace top is adopted to control the temperature of blast furnace top gas to be stable at 250-350℃; the water cooling process of blast furnace top is realized by blast furnace top atomizing water spraying system, the blast furnace top atomizing water spraying system is realized by 16 blast furnace top water spraying guns around the blast furnace top, blast furnace top gas temperature detector and PLC control system, when the 16 blast furnace top water spraying guns are fully opened, the opening degree of blast furnace top atomizing water spraying system is 100%, when one blast furnace top water spraying gun is closed, the opening degree of blast furnace top atomizing water spraying system is reduced by 6.25%, when two or more blast furnace top water spraying guns are closed, the closing is carried out according to the principle of central symmetry; when the temperature of blast furnace top gas is higher than 350℃, the opening degree of blast furnace top atomizing water spraying system is 100%, when the temperature of blast furnace top gas is between 250-350℃, the opening degree of blast furnace top atomizing water spraying system is 50-100%, when the temperature of blast furnace top gas is lower than 250℃, the opening degree of blast furnace top atomizing water spraying system is ≤50%;

[0037] ② Blowing for 1.5h, starting first tapping, when air comes to iron notch, blocking iron notch; during the process of blowing and reducing material level, according to the principle of controlling the temperature of blast furnace top gas not to be higher than 350℃, water cooling process of blast furnace top and gradually reducing blowing flow are adopted to control the temperature of blast furnace top gas to be stable at 250-350℃, cold air flow is gradually reduced to 3000-3200m 3 / min, oxygen flow is gradually closed; during the process, when the temperature of blast furnace top gas is higher than 250℃, the opening degree of blast furnace top atomizing water spraying system is 50-100%, when the temperature of blast furnace top gas is lower than 250℃, the opening degree of blast furnace top atomizing water spraying system is ≤50%;

[0038] ③ When CO in blast furnace top gas is reduced to 28.9% and CO2 is increased to 6.54%, starting second tapping, when air comes to iron notch, blocking iron notch;

[0039] ④ When N2 in blast furnace top gas is increased to 60.85%, material level enters tuyere area, starting third tapping, when air comes to iron notch, blocking iron notch;

[0040] ⑤Third time iron is finished, adopt to remain the coke operation direct stop the blast furnace, the blast furnace changes the normal pressure operation, opens the blast furnace top to release the valve, cuts the gas and rests, the blast furnace top hits the water and cools, completes the blast furnace stop operation, at this time is 22 points 35 minutes, after stopping the blast furnace carries on the furnace hearth cleaning and so on work.

[0041] The blast furnace stop process of the embodiment, the iron temperature is stable at 1495-1505℃, the residual iron amount in the furnace hearth is small after stopping the blast furnace, the furnace wall is clean, meets the requirement of the blast furnace stop repair, the whole stop process takes 10 hours. The cover coke in the furnace hearth after stopping the blast furnace is excavated and continues to be used as the next blast furnace production.

[0042] The blast furnace stop process, saves the washing furnace material cost 164,000 yuan, the labor and time cost 12,000 yuan, the coke cost 36.8,000 yuan, saves the total production cost 212.8,000 yuan.

[0043] Example 2

[0044] The embodiment takes the blast furnace stop method without washing furnace operation of the invention implemented by the No. 2 blast furnace of E'gang on May 9, 2025 as an example to explain the method of the invention in detail. The effective volume of the No. 2 blast furnace of E'gang is 1800m 3 .

[0045] The blast furnace stop method without washing furnace operation of the embodiment includes the following steps:

[0046] (1) Preparation before stopping the blast furnace: the blast furnace starts to unload at 0 o'clock on May 25, 2025, keeps the furnace condition stable and smooth before stopping the blast furnace, ensures the iron temperature of 1528℃, and increases the mass percentage of sulfur in the iron to 0.038%;

[0047] (2) Blast furnace stop steps:

[0048] ① Perform pre-rest operation, after the pre-rest operation is completed, add 2 batches of coke with a total of 24t into the blast furnace, stop charging at 14 o'clock on May 9, the blast furnace starts to blow and lower the material level, the cold air flow is controlled at 4400-4500m 3 / min, the oxygen flow is controlled at 55-75m 3 / min, and the blast furnace top water cooling process is used to control the blast furnace top gas temperature to be stable at 250-350℃; the blast furnace top water cooling process is the same as step (2) of embodiment 1;

[0049] ② Blow for 1.0h, start the first iron tapping, and block the iron notch when the air comes; during the process of blowing and lowering the material level, according to the principle of controlling the blast furnace top gas temperature not to exceed 350℃, the blast furnace top water cooling process and gradually reducing the blowing flow are used to control the blast furnace top gas temperature to be stable at 250-350℃, and the cold air flow is gradually reduced to 3100-3300m 3 / min, oxygen flow is gradually closed; the top water cooling process of this operation process is the same as the second step of step (2) of Example 1;

[0050] ③When CO in the top gas is reduced to 29.5% and CO2 is increased to 6.52%, the second tapping is started, and the iron notch is blocked when the air comes to the iron notch;

[0051] ④When N2 in the top gas is increased to 60.5%, the material surface enters the tuyere area, the third tapping is started, and the iron notch is blocked when the air comes to the iron notch;

[0052] ⑤After the third tapping is completed, the coke remaining operation is used to directly stop the blast furnace, the blast furnace is changed to normal pressure operation, the top diffuser valve is opened, the gas is cut off, the top water cooling is performed, and the blast furnace stopping operation is completed. At this time, it is 22:30, and the furnace cleaning and other work are performed after the blast furnace is stopped.

[0053] In the blast furnace stopping process of this example, the tapping temperature is stable at 1500-1505℃, the residual iron amount in the furnace is small after the blast furnace is stopped, the furnace wall is clean, the requirements of the blast furnace stopping and repair are met, and the whole stopping process takes 8.5 hours. The cover coke in the furnace after the blast furnace is stopped is excavated and used as the blast furnace production of the next furnace.

[0054] In this stopping process, the cost of the furnace cleaning material is saved by 180,000 yuan, the labor and time cost is saved by 16,000 yuan, the cost of the coke is saved by 36,000 yuan, and the total production cost is saved by 232,000 yuan.

[0055] As can be seen from the above examples, the blast furnace stopping method without the furnace cleaning operation of the present application is safe and feasible, the tapping temperature of the blast furnace stopping meets the requirement range of 1480-1505℃, the residual iron amount in the furnace is small after the blast furnace is stopped, the furnace wall is clean, the requirements of the blast furnace stopping and repair are met, the stopping process not only saves a large amount of material, labor and time cost, but also brings good economic benefits and reduces the production cost.

Claims

1. A blast furnace shutdown method without a blowout operation, characterized by It comprises the following steps: (1) Preparation before shutdown: Keep the furnace condition stable and smooth before shutdown, ensure the temperature of molten iron > 1510℃, and the mass percentage of sulfur in molten iron is 0.03-0.04%; (2) Blast furnace shutdown steps: ① Perform pre-blast operation, after pre-blast is finished, add 2 batches of coke to the blast furnace, total 20-25 tons, stop charging, the blast furnace starts to send blast to lower the material level, cold blast flow is controlled at 4400-4500 m 3 / min, oxygen flow is controlled at 50-80 m 3 / min, at the same time, use water cooling process on the blast furnace top to control the temperature of the top gas to be stable at 250-350℃; ②Air supply 1.0-1.5h, start the first tapping, to the iron notch air when plugging the iron notch; air supply to reduce the material surface process with the increase of the temperature of the top gas, according to the principle of control of the top gas temperature should not be more than 350℃, while using the top water cooling process and gradually reduce the air flow to control the top gas temperature stable at 250-350℃, cold air flow gradually reduced to 3000-3500m 3 / min, oxygen gradually closed; ③ When the CO in the top gas is reduced to below 30%, and the CO2 is increased to above 6.5%, start the second tapping, and block the iron notch when the air comes; ④ When the N2 in the top gas is increased to above 60%, and the material surface enters the tuyere area, start the third tapping, and block the iron notch when the air comes; ⑤ After the third tapping, use the coking operation to directly stop the furnace, change the blast furnace to normal pressure operation, open the top diffuser valve, cut off the gas, cool the top with water, complete the blast furnace shutdown operation, and the molten iron temperature is stable at 1480-1505℃, and the time consumption is 8-10 hours.

2. A blast furnace shutdown method without a blowout operation according to claim 1, characterized by: The top water cooling process in step (2) ① is realized by a top atomizing water cooling system, which is composed of 16 water spraying guns around the top, a top gas temperature detector and a PLC control system. When the 16 water spraying guns are fully opened, the opening degree of the top atomizing water cooling system is 100%, and the opening degree of the top atomizing water cooling system is reduced by 6.25% for each closed water spraying gun. When more than two water spraying guns are closed, the closing is carried out in a central symmetric manner. When the top gas temperature is > 350℃, the opening degree of the top atomizing water cooling system is 100%, when the top gas temperature is 250-350℃, the opening degree of the top atomizing water cooling system is 50-100%, and when the top gas temperature is < 250℃, the opening degree of the top atomizing water cooling system is < 50%.

3. A blast furnace shutdown method without a blowout operation according to claim 1 or 2, characterized in that: The top water cooling process in step (2) ②, when the top gas temperature is ≥ 250℃, the opening degree of the top atomizing water cooling system is 50-100%, and when the top gas temperature is < 250℃, the opening degree of the top atomizing water cooling system is < 50%.

4. A blast furnace shutdown method without a blow-in operation according to claim 1 or 2 or 3, characterized in that: The blast furnace is 1800 m 3 Blast furnace.