Method for charging and filling blast furnace blow-in hearth

Abstract

The invention discloses a blast furnace blow-in hearth charging and filling method. A blast furnace hearth is sequentially filled with a coke filling section, a hearth firewood section, a hearth center conical firewood stacking section and a tuyere vertical long wood section from bottom to top. When the furnace is opened, a dead iron layer and the lower portion of the hearth are filled with coke to form a coke filling section, then firewood is laid on the coke filling section to form a hearth firewood section, and then a conical firewood pile is stacked in the center of the hearth firewood section to form a hearth center conical firewood pile section; and finally, obliquely putting long firewood between the hearth firewood section and the hearth side wall above the tuyere along the inner circumferential direction of the hearth to form a tuyere vertical long wood section. The firewood filling amount can be reduced, firewood in the blast furnace hearth can be rapidly combusted, a space beneficial to furnace burden descending is formed, and the furnace top diffusion time is shortened. The height of a coke layer below the tuyere is reduced, so that the temperature drop after high-temperature slag iron enters the hearth is reduced. The furnace cylinder heating speed is high, the first blow-in molten iron temperature can be increased, slag iron can be smoothly discharged, and the blow-in yield reaching and effect reaching speed is increased.

Description

Technical Field

[0001] The invention relates to a method for charging and filling a blast furnace hearth when the furnace is opened, and belongs to the technical field of blast furnace ironmaking production in the metallurgical industry. Background Art

[0002] When a blast furnace is started, it is necessary to fill the furnace with coke, load materials, flux, etc. to meet the heat required for melting slag and iron and heating the furnace lining in the initial stage of furnace opening. At present, the filling of the furnace hearth of a blast furnace is conventionally done by two methods: sleeper filling and coke filling. When the wind temperature is below 600℃, new blast furnaces are generally filled with sleepers; when the wind temperature is above 700℃, sleepers or coke filling can be selected. Generally, small and medium-sized blast furnaces are filled with more coke, while large blast furnaces are generally filled with sleepers. However, both methods have certain disadvantages. First, filling with sleepers wastes a lot of wood, and 3000m 3 When a new blast furnace is opened, 500m2 of sleepers need to be loaded at one time. 3 The above, secondly, the filling of sleepers requires manual handling, placement in the furnace, and long operation time, which consumes a lot of manpower and material resources, delaying the furnace opening time; although the coke filling has a fast loading speed, it also has three disadvantages. First, it takes a long time to ignite the coke at the tuyere in the early stage of furnace opening, especially under low wind temperature conditions, the long ignition time leads to long-term furnace top emission of the blast furnace, polluting the environment; second, due to the slow combustion of coke and the small space formed, the number of "hanging material" accident conditions in the blast furnace has greatly increased in the early stage of soft melting zone formation; third, the high-temperature slag iron formed above the tuyere zone encounters the rapid cooling of the filled cold coke after entering the furnace, resulting in low slag iron temperature and poor fluidity in the early stage of furnace opening, making it difficult to discharge slag iron from the blast furnace, delaying the time for the blast furnace to reach full production and efficiency. In view of this, it should be improved. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for charging the hearth of a blast furnace, which not only reduces the labor intensity of charging, but also takes into account easy ignition, less prone to hanging materials and improving the heat level of the first molten iron when the furnace is opened, thereby solving the problems existing in the above-mentioned prior art.

[0004] The technical solution to solve the above technical problems is: A method for charging and filling a furnace hearth during the start-up of a blast furnace adopts a four-stage charging and filling method. The filling order of the blast furnace hearth from bottom to top is a coke filling section, a hearth wood section, a hearth center conical wood pile section, and a tuyere vertical long wood section. When the furnace is started, firstly, coke is used to quickly fill the dead iron layer and the lower part of the hearth to form a coke filling section, then wood is laid on the coke filling section to form a hearth wood section, then a conical wood pile is piled in the center of the hearth wood section to form a hearth center conical wood pile section, and finally long wood is placed obliquely on the hearth wood section and the hearth side wall above the tuyere along the inner circumference of the hearth to form a tuyere vertical long wood section.

[0005] In the above-mentioned method for charging and filling the blast furnace hearth, the coke filling section plays a role in charging and supporting the furnace charge, and the height of the coke filling section H1=h f - H2; In the formula, h f : The height of the lower edge of the tuyere is generally taken as the height of the center line of the designed tuyere -0.27~-0.33m; H2: Filling height of the hearth firewood section.

[0006] In the above method for charging the furnace hearth when the blast furnace is opened, the height of the firewood section of the furnace hearth is 1.0-2.5m, and miscellaneous wood with a diameter of 0.15-0.3m and a length not greater than 1.5m is filled. The miscellaneous wood in the firewood section of the furnace hearth is quickly ignited at the initial stage of the blast furnace opening, so as to heat the furnace hearth and the charge, and at the same time, the burning frees up space for the upper charge to fall freely, so as to prevent the hanging charge at the initial stage of the furnace opening; In the above-mentioned method for charging the furnace hearth when the blast furnace is opened, the diameter Dm of the conical firewood pile section in the center of the furnace hearth is 3.5-9.0 m, and the function of this section is to facilitate the generation of central coal gas flow at the initial stage of furnace opening, so as to promote the formation of a reasonable soft melting zone; The vertical long wood section at the tuyere is composed of miscellaneous wood obliquely placed between the furnace wood section and the furnace side wall above the tuyere along the inner circumference of the furnace, the miscellaneous wood is 1.3-1.5m long and 0.15-0.3m in diameter, one end of which is placed on the furnace wall above the tuyere, and the other end is placed on the upper surface of the furnace wood section, forming an angle of 25º-60º with the horizontal direction. The present invention sets the vertical long wood section at the tuyere, and the long wood overlapped at the tuyere can not only protect the tuyere and prevent the impact of coke on the cooling device when loading the furnace, but also form a low ignition point area around the tuyere, which is convenient for rapid ignition at the initial stage of air supply.

[0007] The amount of miscellaneous wood used for the above-mentioned vertical long wood sections at the tuyere should be sufficient to cover the entire tuyere area. The calculated amount is n=π×D / d 木 ; In the formula, n is the amount of long wood pieces placed at the tuyere, roots; D is the furnace diameter, m; d 木 The diameter of miscellaneous wood is generally 0.15-0.30m.

[0008] The beneficial effects of the present invention are that the heights of each section of the furnace charging filling material are quantified in advance, the amount of coke and firewood used is clarified, and the preparation of production materials is convenient; on the other hand, the four-stage furnace charging and filling method can reduce the amount of firewood filling by more than 1 / 2 compared with the method of filling the furnace with firewood, thereby reducing the labor intensity of loading firewood; compared with the method of filling the furnace with full coke, the disadvantages of slow ignition speed of the coke filling tuyere and long furnace top release time are avoided. At the same time, since the height of the coke layer below the tuyere is reduced, combined with the iron mouth oxygen-enriched blast, the temperature drop of high-temperature slag iron above the tuyere after entering the furnace can be reduced, and the temperature of slag iron in the furnace can be increased by 20% faster, which can increase the temperature of the first molten iron when the furnace is opened by 15-40°C, which is conducive to the smooth discharge of slag iron, reduces the workload in front of the furnace, and accelerates the speed of opening the furnace to reach production and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of filling the blast furnace hearth; The markings in the figure are: 1. Coke filling section, 2. Firewood section in the furnace, 3. Conical firewood pile section in the center of the furnace, 4. Long wood section placed upright at the tuyere; 5. Furnace wall. DETAILED DESCRIPTION

[0010] Example 1 A 3200m 3 Blast furnace filling operation during blast furnace start-up Firstly, it was determined that the furnace hearth loading for this blast furnace opening would adopt a four-stage loading method, and the filling order from bottom to top was: coke filling section, hearth firewood section, hearth center conical firewood pile section and tuyere vertical long wood section.

[0011] In order to facilitate the organization of production and ensure the smooth progress of the furnace loading process, the following calculations were carried out before the furnace loading to facilitate the smooth implementation of the blast furnace filling operation.

[0012] A factory 3200m 3 The blast furnace was restarted after being shut down for overhaul. The main parameters of the blast furnace are as follows:

[0013] (1) Calculate the height H2 of the firewood section of the furnace and the amount of firewood The 3200m 3 When the blast furnace is in normal production, the depth of its raceway is 1.75m. Referring to the empirical value, the height H2 of the firewood section of the furnace hearth is selected as 2.0m for this furnace opening.

[0014] Amount of firewood = π × D × D / 4 × H2 =3.14×12.69×12.69 / 4×2.0 = 252.8m 3 According to the calculation of 50% bulk wood filling rate, the second section of the furnace needs 252.8×0.5=126m3 (2) Calculate the height H1 of the coke filling section and the number of coke batches to be loaded According to the formula: H1=H f -H2 H1=H f -H2=7.05-2=5.05m The blast furnace was not discharged during the overhaul. Considering that there is still 1.3 meters of condensed iron, the height of coke required to be filled after deducting the condensed iron in the dead iron layer is 5.05-1.3=3.75m. The volume of coke required to be filled is π×D×D / 4×H1=3.14×12.69×12.69 / 4×3.75 =474m 3 According to the coke pile specific gravity of 0.55t / m 3 , the compression rate is 10%, and the total weight of coke required is: 474×0.55÷(1-10%)=289.7t The coke batch setting value for blast furnace opening is 22t / ch, and the total number of coke batches to be loaded into the coke filling section is 289.7÷22=13.17, 13 batches of values (3) Calculate the amount of firewood required for the conical firewood pile section in the center of the furnace The 3200m 3 The diameter of the blast furnace hearth is 12.69m. In order to form an inverted "V"-shaped soft melting zone, the diameter Dm of the central conical firewood pile is selected to be 7.5m and the height is 2.0 meters when arranging the central conical firewood pile, so as to facilitate the timely generation of central development type gas distribution after the furnace is started and ignited.

[0015] The volume of the central conical firewood pile is: 3.14×7.5 ×7.5 / 4 / 3×2 =29.4m 3 The porosity of the stacked firewood is 10%, so the amount of firewood required for the central conical firewood pile is: 29.4×(1-10%)=26.5m 3 (4) Calculate the number of miscellaneous woods n that are overlapped by long wood sections placed vertically at the air outlet The 3200m 3 The diameter of the long logs placed vertically in the tuyere for filling the blast furnace hearth is about 0.2m and the length is about 2.0m.

[0016] According to the formula, the number of miscellaneous woods overlapped by long wood sections placed at the air outlet is n=π×D / d 木 =3.14×12.69 / 0.2 =199 (root) The volume of this part of miscellaneous wood is calculated based on a diameter of 0.2m and a length of 2.0m: 3.14 × 0.2 × 0.2 / 4 × 2 × 199 =12.5m 3 (5) Based on the above calculations, the filling scheme for the blast furnace hearth is: The coke filling section was loaded with 13 batches of coke, with a total weight of 22 tons and a total of 286 tons; the total amount of firewood loaded in the furnace firewood section was 126m 3 ; The volume of the conical firewood pile in the center of the furnace is 26.5m 3 ; Place long wooden sections vertically at the air outlet and overlap long wooden sections 12.5m 3 The total amount of firewood is 165m 3 .

[0017] Blast furnace hearth charging and filling operation process: 3200m 3 Blast furnace filling operation performance after opening: First, use coke to quickly fill the dead iron layer and the lower part of the furnace to form a coke filling section.

[0018] On the night shift of December 28, 13 cans of coke weighing 286 tons were loaded into the blast furnace as planned. After the coke filling section was formed in the furnace, the height from the upper surface of the coke to the center line of the tuyere was 2.1 meters. After deducting the height of the dead iron layer, the height of the coke filling section H1=h f - H2=7.05-1.3-2.1+0.3=3.95m.

[0019] The second step is to lay firewood on the coke filling section to form a furnace firewood section.

[0020] On December 29, the day shift loaded miscellaneous wood with a length of 0.8-1.5m and a diameter of 0.15-0.3m into the blast furnace hearth from the blast furnace tuyere, and laid firewood in the hearth above the coke filling section while loading, until the upper surface of the firewood reached the lower edge of the tuyere, forming a hearth firewood section. In this process, a total of firewood was loaded, and the height of the hearth firewood section was 1.8m.

[0021] The third step is to build a conical firewood pile section in the center of the hearth on the firewood section of the hearth.

[0022] During the middle shift on December 29, the operator entered the blast furnace from the tuyere and promptly placed the firewood needed to be loaded into the pyramid firewood pile in the center of the hearth from the tuyere. The firewood pile had a diameter Dm of 7.5m and a height of 2.1m, forming a conical firewood pile section in the center of the hearth.

[0023] The fourth step is to place miscellaneous wood to form air vents by placing long logs upright.

[0024] During the middle shift on December 29, after the pyramid firewood pile in the center of the furnace was completed, miscellaneous wood with a diameter of 0.2m and a length of 2.0m continued to be fed in through the tuyere. The operator placed them one by one in an oblique manner at the front end of the tuyere, along the furnace firewood section along the inner circumference of the furnace and the side wall of the furnace above the tuyere, forming long wood sections placed upright in the tuyere, which played a role in protecting the tuyere when the furnace was opened and loaded.

[0025] This furnace is filled with 160m3 of firewood. 3 . After the furnace is filled with materials, clean coke, empty coke and load materials for blast furnace start-up are loaded. The loading of materials for blast furnace start-up was completed on December 31, and the blast furnace material line was measured to be 1.4m, which is consistent with the blast furnace start-up and loading plan. The blast furnace was supplied with air at 0:00 on January 1, 2022, and all the air ports were lit within 3 minutes of air supply. After air supply, the blast furnace control room controlled the gas release and top pressure, and the blast furnace quickly increased the air volume to 3000m 3 / min, and the coal gas introduction operation was carried out 48 minutes later; since the filling material in the furnace was suitable and the probe dynamics were good after the air was supplied, the first temperature of the molten iron after the furnace was opened was 1368℃, and the temperature was 1409℃ before the end of iron tapping. The slag iron had good fluidity and went directly to the formal carbon bag and water slag flushing.

Claims

1. A method for charging a blast furnace hearth during furnace opening, characterized in that , a four-stage furnace loading method is adopted, and the filling order of the blast furnace hearth from bottom to top is coke filling section (1), hearth firewood section (2), hearth center conical firewood pile section (3) and tuyere vertical long wood section (4); when the furnace is started, coke is first used to fill the dead iron layer and the lower part of the hearth to form the coke filling section (1), then firewood is laid on the coke filling section (1) to form the hearth firewood section (2), then a conical firewood pile is piled in the center of the hearth firewood section (2) to form the hearth center conical firewood pile section (3), and finally long firewood is obliquely placed between the hearth firewood section (2) and the hearth side wall above the tuyere along the inner circumference of the hearth to form the tuyere vertical long wood section (4).

2. The method for charging a blast furnace hearth during opening of a blast furnace according to claim 1, characterized in that The coke filling section (1) plays a role in charging and supporting the furnace charge. The height of the coke filling section H1=h f -H2; In the formula, h f : The lower edge height of the tuyere is -0.27~-0.33m from the center line height of the designed tuyere; H2: Filling height of the hearth firewood section.

3. The method for charging and filling the blast furnace hearth according to claim 1, characterized in that The height H2 of the furnace firewood section (2) is 1.0-2.5m; it is filled with miscellaneous wood with a diameter of 0.15-0.3m and a length not greater than 1.5m.

4. The method for charging and filling a blast furnace hearth during furnace opening according to claim 1, characterized in that , the diameter of the conical firewood pile section in the center of the furnace is D m 3.5-9.0m.

5. The method for charging and filling the blast furnace hearth according to claim 1, characterized in that The long wood section (4) placed vertically at the tuyere is composed of miscellaneous wood placed obliquely between the hearth wood section (2) and the hearth side wall above the tuyere along the inner circumference of the hearth. The miscellaneous wood is 1.3-1.5 m long and 0.15-0.3 m in diameter. One end of the miscellaneous wood is placed on the furnace wall above the tuyere, and the other end is placed on the upper surface of the hearth wood section (2) at an angle of 25°-60° to the horizontal direction to protect the tuyere and accelerate ignition.

6. The method for charging and filling the blast furnace hearth according to claim 5, characterized in that , the amount of miscellaneous wood used for the vertical long wood section (4) of the tuyere is n=π×D / d 木 ; In the formula, n is the amount of long wood pieces placed at the tuyere, roots; D is the furnace diameter, m; d 木 is the diameter of miscellaneous wood, m.

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