Optimized operation method for blast furnace

Abstract

The invention relates to the technical field of metallurgy, in particular to a blast furnace optimized operation method which comprises the steps that an air supply system is adjusted, a charging system corresponding to the air supply system is adjusted, and the air supply system comprises the steps of adjusting air supply parameters, controlling the annulus area ratio of a tuyere rotation area and controlling the gas volume; the charging system comprises control over upper airflow, control over furnace burden distribution and control over coal gas flow distribution. By optimizing the air supply parameters and the charging system, the production efficiency, the energy utilization rate and the environmental protection performance of the blast furnace are remarkably improved, and the balance of a temperature field, airflow distribution and material distribution in the blast furnace is realized, so that the overall operation effect of the blast furnace is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a blast furnace optimization operation method. Background Art

[0002] As a key equipment in steel production, the operating efficiency and product quality of the blast furnace directly affect the economic benefits and environmental protection level of the enterprise. Low-cost smelting of blast furnaces is an inevitable requirement. The main problem restricting the realization of low costs is that the blast furnace cannot be stable for a long time. There are many factors that affect stability. In summary, there are three problems: raw material fluctuations, equipment problems, and blast furnace operation system. The contradictions of the three movements of gas, solid and liquid in the furnace cause the destruction of the rules and order. Therefore, finding a suitable blast furnace operation method to solve the problem that the blast furnace cannot be stable for a long time is of great significance to improving the production performance of the blast furnace. Summary of the invention

[0003] In order to solve the defects in the prior art, the present invention provides a blast furnace optimization operation method. The present invention significantly improves the production efficiency, energy utilization rate and environmental protection performance of the blast furnace by optimizing the air supply parameters and the charging system, and realizes the balance of the temperature field, airflow distribution and material distribution inside the blast furnace, thereby improving the overall operation effect of the blast furnace.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for optimizing the operation of a blast furnace, comprising adjusting an air supply system and adjusting a corresponding charging system, wherein the air supply system comprises adjusting air supply parameters, controlling the ring area ratio of a tuyere raceway, and controlling gas volume; the charging system comprises controlling upper airflow, controlling furnace charge distribution, and controlling coal gas flow distribution.

[0006] Preferably, the air supply parameters include: controlled air pressure of 370-400 kPa, oxygen enrichment rate of 3.5-5.5%, top pressure of 200-220 kPa, air temperature of 1220-1240°C, theoretical combustion temperature of 2280-2320°C, air outlet area of ​​0.230-0.2450 m 2 , actual wind speed is 250-280m / s.

[0007] Preferably, the air supply parameters also include: gas volume index: furnace belly 65-75; furnace throat gas flow rate: ≤1.0m / s.

[0008] Preferably, the annular zone area of ​​the control tuyere raceway is 0.6 of the total area of ​​the furnace.

[0009] Preferably, the controlled gas volume is obtained by reducing the wind consumption per ton of iron and the amount of coal gas consumed per ton of iron.

[0010] More preferably, the wind consumption per ton of iron and the amount of coal gas per ton of iron can be reduced by increasing the oxygen enrichment rate to 4.5-5.5%, increasing the coal gas utilization rate to 42%-44%, and controlling the furnace gas index to 60Nm 3 / min.m 2 , the top pressure is increased to above 220kpa, the air temperature is controlled to 1230℃, and the oxygen quantity entering the furnace per unit time is controlled to 13000m 3 / h can be obtained by any one or several methods.

[0011] Preferably, the method for controlling the upper airflow is: by adjusting the number of distribution gears and the number of distribution circles on the gears, to control the width of the distribution platform and the O / C distribution in the radial direction, and by adjusting the starting distribution gear and gear angle, to control the distance between the starting drop point and the steel brick, so as to form a suitable and stable layered furnace charge platform, a reasonable and stable coal gas flow distribution, and a temperature field distribution.

[0012] Preferably, the control of charge distribution comprises the following steps:

[0013] (1) The O / C distribution in the radial direction is adjusted. The present invention controls the airflow distribution to be an "inverted trumpet flower" shape, with "two-channel" airflow distribution that is slightly stronger at the edge and the center;

[0014] (2) Starting material drop point position: The present invention controls the outermost side of the material flow to be about 100-300 mm away from the steel brick;

[0015] (3) Gear Angle: Divide into 8 to 13 gears according to equal area to ensure that the thickness of the material layer is the same when the number of cloth turns is the same;

[0016] (4) Distribution operation: Each gear has 2 to 4 distribution circles of ore or coke. The number of distribution circles in each gear should not be too many. Try to reduce the impact of concentrated ore distribution on coke, which will cause the collapse of the coke layer and make the local coke window layer too thin. It is also necessary to avoid excessive coke distribution at both ends, which will cause the middle coke window layer to be too thin, seriously affecting the reasonable distribution of airflow, causing material unsmoothness and airflow disorder.

[0017] (5) Change the charge distribution by changing the chute tilting mode: distribute the charge in sequence according to the gear position;

[0018] (6) Reduce the error of material distribution: The total number of material distribution turns: The total number of turns should be determined according to the batch size and the size of the charge particle size, so that the opening of the material flow valve is as close to the middle 45° as possible to avoid the material flow valve opening being too large or too small, and the uneven material flow size affecting the actual number of material distribution turns;

[0019] (7) Adjustment of the width of the distribution platform and the change of raw materials and fuels: The width of the platform is about 1 / 3 of the furnace throat radius and about 1 / 2 of the furnace throat area.

[0020] Preferably, the control of coal gas flow distribution is to monitor coal gas flow distribution by means of furnace top video, furnace throat cross temperature measurement, furnace top comprehensive coal gas composition online monitoring, and furnace body temperature.

[0021] The beneficial effects of the present invention are:

[0022] The change of temperature field in the furnace determines the interaction and transformation of gas, solid and liquid, the airflow distribution determines the temperature field distribution, the air supply system, the charge distribution, etc. determine the airflow distribution, and the core operating technology to achieve long-term forward stability of the blast furnace and improve the utilization rate of coal gas is: maintain the reasonable distribution of blast furnace coal gas flow, solve the main contradiction of the three movements of gas, solid and liquid, avoid liquid-solid reverse conversion, so as to reduce costs. The present invention significantly improves the production efficiency, energy utilization and environmental protection performance of the blast furnace by optimizing the air supply parameters. The method includes flexible adjustment of the air supply system, optimization of the charging sequence and structure, aiming to achieve the balance of the temperature field, airflow distribution and material distribution inside the blast furnace, thereby improving the overall operation effect of the blast furnace. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0024] Example 1

[0025] This embodiment achieves long-term smooth operation and stability of the blast furnace by adjusting the air supply system and charging system of the blast furnace. The specific control is as follows:

[0026] (I) Optimize the air supply system

[0027] The air supply system is the most active factor, driving force, and the main factor affecting the primary air flow distribution.

[0028] 1 Reasonable air supply parameters:

[0029] The appropriate wind pressure is controlled to be 370-400kpa, oxygen enrichment rate is 3.5-5.5%, top pressure is 200-220kpa, wind temperature is 1220-1240℃, theoretical combustion temperature is 2280-2320℃, and air outlet area is 0.230-0.2450m 2 , actual wind speed 250-280m / s; gas volume index: furnace belly 65-75; gas flow rate in furnace throat: ≤1.0m / s.

[0030] The present invention controls the above air supply parameters to make the gas flow distribution reasonable, promote smoothness and improve indicators.

[0031] 2. Control the ring area ratio of the tuyere swirl zone

[0032] The distribution of coal gas flow in the blast furnace, especially the initial coal gas flow distribution, is closely related to the motion state of the raceway. 3 / min, the air outlet area is 0.23-0.245m 2 , so that the area of ​​the tuyere raceway reaches about 0.6 of the total furnace area. It is calculated that when the tuyere raceway is equal to 0.5, the best air permeability and fuel ratio of 530-550kg / ton iron can be obtained.

[0033] One of the main factors affecting the depth of the cyclonic zone is the kinetic energy of the wind. In some embodiments of the present invention, the wind volume is controlled to be 3250m 3 In other embodiments of the present invention, the controlled air volume is 3350m 3 The study found that the increase in wind volume increased the kinetic energy of the blast by 15,000 kJ / S, and the length of the whirlpool zone also increased from 2 m to 2.32 m.

[0034] In addition, according to the above parameters, the appropriate tuyere area and the length extending into the furnace should be controlled to achieve a reasonable matching relationship with multiple parameters such as wind oxygen volume, wind temperature, wind pressure (top pressure), etc. The corresponding relationship of each parameter is shown in Table 1 (BF3 and BF4 are different implementation methods based on the matching of the above parameter range values):

[0035] Table 1

[0036]

[0037] Note: △P: pressure difference, TP: top pressure, TT: top temperature.

[0038] The volume of coal gas can be reduced by properly controlling the wind and raising oxygen, thereby reducing the coal gas flow rate in the furnace, prolonging the reaction time of coal gas in the furnace, improving indirect reduction, and promoting CO to CO 2 Conversion.

[0039] 3. Control gas volume to promote stable furnace conditions, increase production and reduce consumption

[0040] 1) Under the same conditions, reducing the amount of coal gas per ton of iron can reduce the gas flow rate, reduce the conflict between the movement of gas, solid and liquid, and is conducive to the smooth and stable feeding. In some embodiments of the present invention, increasing the oxygen enrichment rate to 4.5-5.5% and increasing the coal gas utilization rate to 42%-44% can reduce the fuel ratio, both of which can reduce the wind consumption per ton of iron and the amount of coal gas per ton of iron.

[0041] High oxygen enrichment can increase production and N in coal gas 2 Reducing the amount of coal gas generated per ton of iron is beneficial to increasing the coal injection ratio and hot blast furnace burning.

[0042] One of the indicators for measuring the amount of gas per ton of iron is the gas volume index of the furnace. The gas volume index of the furnace is controlled to be 60 (Nm3 / min.m 2 )(i.e. 60m / min); that is, the standard flow velocity in the cavity is about 1m / s.

[0043] 2) High top pressure operation can compress the actual volume of coal gas in the furnace, reduce the coal gas flow rate in the furnace (pore working condition flow rate), reduce the resistance of the descending charge, which is beneficial to the stability of coal gas flow and the smooth running stability of the blast furnace; prolong the contact time between coal gas and charge, promote indirect reduction, and help improve coal gas utilization.

[0044] According to the conditions of the furnace top equipment, hot and cold air ducts, gas pipelines and other equipment and the furnace conditions, the top pressure will be gradually increased to above 220kpa, and the pressure difference will be less than 180kpa.

[0045] 3) High wind temperature (1230℃), hot wind is the direct heat source of the blast furnace (accounting for about 19% of the heat income), increasing wind temperature can reduce fuel consumption and help increase the coal injection ratio. Although increasing wind temperature increases the gas working volume, reducing fuel consumption can reduce the amount of gas per ton of iron.

[0046] By preheating coal gas and combustion-supporting air to above 180°C, optimizing the automatic furnace burning and furnace changing modes, adopting high-efficiency burners with low air excess coefficient (≤1.05), high-efficiency checker bricks, parallel air supply, and hot waste air recovery and pressurization during furnace changing (recovering half of the furnace hot air and reducing the oxygen content of waste gas for powder making), the difference between wind temperature and top temperature is reduced to below 80°C, and all blast furnace gas (oxygen-enriched blast furnace) is burned, or the pre-furnace is used to make the average wind temperature above 1250°C. Giving full play to the potential of the hot air system is an effective means of reducing costs. Raising the wind temperature by 100°C will reduce the coke ratio by about 20-10kg / t.

[0047] When the theoretical combustion temperature is too low, the fuel is not fully burned, resulting in insufficient furnace temperature. When it is too high, the temperature distribution in the radial direction of the furnace is unreasonable, resulting in a large amount of SiO volatilizing to the upper part and re-condensing, which will deteriorate the permeability of the material column and affect the smooth operation of the blast furnace. The theoretical combustion temperature of the present invention is generally controlled at about 2250±50℃.

[0048] 5) Increase production and reduce consumption: How to reduce iron ore efficiently within a limited volume per unit time is the key. The oxygen volume entering the furnace per unit time is controlled to be 13000m 3 / h, reduce fuel consumption to 540kg / ton iron, and reduce air volume per ton of iron.

[0049] (II) Optimizing the loading system

[0050] In coordination with the air supply system, etc., under the existing conditions, all operating means are fully utilized scientifically and rationally to adjust the gas distribution in the blast furnace and the rational movement of the charge, so as to complete the tasks of heating, reducing, melting, slagging, desulfurization, carburizing, slag and iron separation and smooth flow out of the blast furnace.

[0051] 1. The method of controlling the airflow at the top: generally, the charging mode, material line, batch weight, etc. are changed to control the radial charge and O / C distribution, so as to form a suitable and stable layered charge platform, a reasonable and stable gas flow distribution, and a temperature field distribution.

[0052] The present invention controls the width of the material distribution platform and the O / C distribution in the radial direction by adjusting the number of material distribution gears and the number of material distribution circles on the gears, and controls the distance between the starting material drop point and the steel brick by adjusting the starting material distribution gear and the gear angle, so as to form a suitable and stable layered furnace charge platform, a reasonable and stable gas flow distribution, and a temperature field distribution.

[0053] 2. Reasonable distribution of furnace charge keeps gas in reasonable distribution, promotes smoothness and improves gas utilization rate

[0054] To establish a stable layered charge distribution platform:

[0055] (1) The O / C distribution is adjusted in the radial direction. The present invention controls the airflow distribution to be an "inverted trumpet flower" shape, with "two-channel" airflow distribution slightly stronger at the edge and in the center, which is conducive to smoothness and improvement of gas utilization.

[0056] (2) Position of the starting material landing point: The present invention controls the outermost side of the material flow to be about 100-300 mm away from the steel brick. If it is too far or too close to the furnace wall, it may cause the charge to roll, slide or even collapse after reaching the material surface, causing chaotic distribution of the charge.

[0057] (3) Shift angle: Before opening the furnace, the shift angles corresponding to different material lines should be measured, especially the starting shift angle of the commonly used material lines should be found. In principle, the shift angles are divided into 8 to 13 shifts according to equal areas, so that the material layer thickness is equivalent when the number of shifts is the same.

[0058] (4) Distribution operation: Each gear has 2 to 4 distribution circles of ore or coke. The number of circles in each gear should not be too much. Try to minimize the impact of concentrated distribution of ore on coke, which may cause the collapse of the coke material layer and make the local coke window layer too thin. It is also necessary to avoid excessive distribution of coke at both ends, which may cause the middle coke window layer to be too thin, seriously affecting the reasonable distribution of airflow, causing material unsmoothness and chaotic airflow.

[0059] (5) Change the charge distribution by changing the tilting mode of the chute: distribute the charge in sequence according to the gear position.

[0060] (6) Reduce fabric errors:

[0061] Total number of distribution circles: The total number of circles should be determined according to the batch size and the charge particle size to ensure that the flow rate is as close to the middle 45° as possible to avoid excessive or small opening of the flow valve. Uneven flow rates will affect the actual number of distribution circles (actual performance).

[0062] (7) Adjustment of the width of the distribution platform and the change of raw materials and fuels:

[0063] The core of bellless material distribution is the formation of the material surface platform. Ensure the appropriate platform width and funnel depth, because the platform is small, the funnel is deep, the material surface is unstable; the platform is large, the funnel is shallow, and the central airflow is suppressed. Therefore, the throat material surface should be composed of an appropriate platform and a rolling funnel. The appropriate platform width is the key to stable airflow.

[0064] 4 to 8 gears are commonly used (gear angle span 8° to 12°), and the width of the distribution platform of the present invention is about 1 / 3 of the furnace throat radius and about 1 / 2 of the furnace throat area. The distribution platform of the central coke blast furnace should be appropriately wider.

[0065] 4. Reasonable gas flow distribution

[0066] The gas flow distribution is monitored by furnace top video, furnace throat cross temperature measurement, furnace top comprehensive gas composition online monitoring and furnace body temperature.

[0067] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for optimizing blast furnace operation, characterized in that: It includes adjusting the air supply system and the corresponding charging system, wherein the air supply system includes adjusting the air supply parameters, controlling the ring area ratio of the tuyere vortex zone, and controlling the gas volume; the charging system includes controlling the upper airflow, controlling the distribution of furnace charge, and controlling the coal gas flow distribution.

2. The blast furnace optimization operation method according to claim 1, characterized in that: The air supply parameters include: controlled air pressure of 370-400 kPa, oxygen enrichment rate of 3.5-5.5%, top pressure of 200-220 kPa, air temperature of 1220-1240°C, theoretical combustion temperature of 2280-2320°C, air outlet area of ​​0.230-0.2450 m 2 , actual wind speed is 250-280m / s.

3. The blast furnace optimization operation method according to claim 2, characterized in that: The air supply parameters also include: gas volume index: furnace belly 65-75; furnace throat gas flow velocity: ≤1.0m / s.

4. The blast furnace optimization operation method according to claim 1, characterized in that: The annular zone area of ​​the control tuyere raceway is 0.6 of the total area of ​​the furnace.

5. The blast furnace optimization operation method according to claim 1, characterized in that: The controlled gas volume is obtained by reducing the wind consumption per ton of iron and the coal gas consumption per ton of iron.

6. The blast furnace optimization operation method according to claim 5, characterized in that: Reduce the air consumption per ton of iron and the amount of coal gas per ton of iron by increasing the oxygen enrichment rate to 4.5-5.5%, increasing the coal gas utilization rate to 42%-44%, and controlling the furnace gas index to 60Nm 3 / min.m 2 , the top pressure is increased to above 220kpa, the air temperature is controlled to 1230℃, and the oxygen quantity entering the furnace per unit time is controlled to 13000m 3 / h can be obtained by any one or several methods.

7. The blast furnace optimization operation method according to claim 1, characterized in that: The method for controlling the upper airflow is as follows: by adjusting the number of distribution gears and the number of distribution circles on the gears, the width of the distribution platform and the O / C distribution in the radial direction are controlled; by adjusting the starting distribution gear and the gear angle, the distance between the starting drop point and the steel brick is controlled to form a suitable and stable layered furnace charge platform, a reasonable and stable gas flow distribution, and a temperature field distribution.

8. The blast furnace optimization operation method according to claim 1, characterized in that: The control of charge distribution comprises the following steps: (1) The O / C distribution in the radial direction is adjusted. The present invention controls the airflow distribution to be an "inverted trumpet flower" shape, with "two-channel" airflow distribution that is slightly stronger at the edge and the center; (2) Starting material drop point position: The present invention controls the outermost side of the material flow to be about 100-300 mm away from the steel brick; (3) Gear Angle: Divide into 8 to 13 gears according to equal area to ensure that the thickness of the material layer is the same when the number of cloth turns is the same; (4) Distribution operation: Each gear has 2 to 4 distribution circles of ore or coke. The number of distribution circles in each gear should not be too many. Try to reduce the impact of concentrated ore distribution on coke, which will cause the collapse of the coke layer and make the local coke window layer too thin. It is also necessary to avoid excessive coke distribution at both ends, which will cause the middle coke window layer to be too thin, seriously affecting the reasonable distribution of airflow, causing material unsmoothness and airflow disorder. (5) Change the charge distribution by changing the chute tilting mode: distribute the charge in sequence according to the gear position; (6) Reduce the error of material distribution: The total number of material distribution turns: The total number of turns should be determined according to the batch size and the size of the charge particle size, so that the opening of the material flow valve is as close to the middle 45° as possible to avoid the material flow valve opening being too large or too small, and the uneven material flow size affecting the actual number of material distribution turns; (7) Adjustment of the width of the distribution platform and the change of raw materials and fuels: The width of the platform is about 1 / 3 of the furnace throat radius and about 1 / 2 of the furnace throat area.

9. The blast furnace optimization operation method according to claim 1, characterized in that: The control of coal gas flow distribution is to monitor coal gas flow distribution by means of furnace top camera, furnace throat cross temperature measurement, furnace top comprehensive coal gas composition online monitoring, and furnace body temperature.

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