Method and device for charging raw materials into a vertical carbonization furnace

Abstract

To provide a raw material charging method and a raw material charging apparatus for a vertical pyrolysis furnace for ferro coke production that prevents segregation of fine grains generated from molded raw materials in a depth direction and enables uniform heating of raw materials.SOLUTION: A raw material charging method for a vertical pyrolysis furnace comprises injecting gas in the vicinity of a charge entrance / exit to disperse fine grains in a raw material when charging the raw material into a pyrolysis furnace from a charge entrance. The raw material is a molded raw material, a particle size of the fine grains is 15 mm or less, the gas to be injected is air or a nitrogen gas, a jet velocity of the gas into the furnace is preferably 7 m / s to 25 m / s, and an injection angle θ of the gas into the furnace is preferably 90° to 135° with respect to an inclined plane of the charge entrance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for charging raw materials into a vertical carbonization furnace, and more particularly to a method and apparatus for charging raw materials into a vertical carbonization furnace for producing ferro-coke, which prevents segregation of fine particles that occurs during the transportation process when charging briquette raw materials into the vertical carbonization furnace and enables the raw materials to be heated uniformly. [Background technology]

[0002] In recent years, in order to improve the efficiency of the steelmaking process in blast furnaces, it has been proposed to replace part of the coke charged into blast furnaces with ferro-coke. Ferro-coke is a molded coke produced by carbonizing a mixture of carbon-containing materials (such as coal) and iron-containing materials (such as iron ore). Generally, a carbonization method using a vertical carbonization furnace has been proposed.

[0003] For example, Patent Document 1 discloses a method for producing ferro-coke using a vertical carbonization furnace having a carbonization zone at the top and a cooling zone at the bottom. This ferro-coke production method begins with a charging step in which molded materials composed of a carbon-containing material and an iron-containing material are charged into the vertical carbonization furnace. Next, in the carbonization step, heated gas is injected into the carbonization zone to carbonize the molded materials and produce ferro-coke. Subsequently, in the cooling step, cooling gas is injected into the cooling zone to cool the ferro-coke. Furthermore, the process includes an in-furnace gas discharge step in which furnace gas is discharged from an outlet at the top of the vertical carbonization furnace, and a ferro-coke discharge step in which ferro-coke is discharged from the bottom of the cooling zone. During the carbonization step, low-temperature gas is injected from a tuyere located in the middle of the vertical carbonization furnace, and high-temperature gas is injected from a tuyere located at the bottom of the vertical carbonization furnace.

[0004] Thus, when producing ferro-coke using a vertical carbonization furnace, in order to increase the amount of ferro-coke produced, it is necessary to increase the volume of the vertical carbonization furnace and increase the production volume per batch. However, because the cooling gas and high-temperature gas are injected in the depth direction of the vertical carbonization furnace (from the gas injection side to the opposite side), the depth direction of the furnace body cannot be increased beyond a certain level in order for the gas to penetrate to the center of the furnace. Therefore, the shape (horizontal cross-sectional shape) of a vertical carbonization furnace is longer in the furnace width direction (direction perpendicular to the depth direction) than in the depth direction.

[0005] Furthermore, if there is an imbalance in the charging balance when charging the briquettes into the furnace, the gas flow in the furnace becomes uneven, which adversely affects the carbonization of the briquettes. Therefore, as technologies for uniformly carbonizing the briquettes in a vertical carbonization furnace, Patent Document 2 discloses a distributed raw material charging technology, and Patent Document 3 discloses a uniform gas injection technology. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-57970 [Patent Document 2] Japanese Patent Application Publication No. 2017-155214 [Patent Document 3] Japanese Patent Application Publication No. 2018-172650 Summary of the Invention [Problem to be solved by the invention]

[0007] The device proposed in Patent Document 2 is said to enable the raw materials to be charged uniformly in the width direction, making it possible to produce high-quality ferro-coke with high productivity. However, the technology in Patent Document 2 does not have the effect of charging the raw materials uniformly in the depth direction, and there is a problem in that the effect of uniform gas injection is reduced due to the segregation of fine particles, in particular, toward the charging port side.

[0008] Furthermore, the device proposed in Patent Document 3 claims that by adding a gas inlet, the raw materials can be heated uniformly and the temperature difference in the furnace can be reduced, thereby suppressing the variation in the quality of the ferro-coke. However, the technology in Patent Document 3 has the problem that the vertical carbonization furnace itself and the peripheral equipment become complicated, which increases the costs required for construction and maintenance.

[0009] The present invention has been developed in view of the above-mentioned circumstances, and aims to provide a method and device for charging raw materials into a vertical carbonization furnace for producing ferro-coke, which can prevent fine particles generated from the briquette raw material from segregating in the depth direction and enable the raw materials to be heated uniformly. [Means for solving the problem]

[0010] The present inventors conducted extensive research to solve the above-mentioned problems. As a result, they found that fine particles generated during the transport of the briquette raw material charged into a vertical carbonization furnace segregate toward the charging inlet, which is located at the front of the furnace depth, causing variations in particle size of the charged deposit and resulting in non-uniform gas injection in the carbonization zone. They further found that the particle size of the charged deposit can be made uniform by injecting gas near the furnace outlet of the charging inlet to uniformly disperse the fine particles within the furnace.

[0011] The present invention was completed based on these findings and further investigations, and the gist of the present invention is as follows. [1] A method for charging raw materials into a vertical carbonization furnace, characterized in that when the raw materials are introduced into the vertical carbonization furnace through a charging port, gas is injected into the raw materials through the charging port to disperse fine particles in the raw materials. [2] The method for charging raw materials into a vertical carbonization furnace according to [1], wherein the raw material is a briquette raw material and the particle diameter of the fine particles is 15 mm or less. [3] The method for charging raw materials into a vertical carbonization furnace according to [1] or [2], wherein the weight ratio of the fine particles in the raw material for briquettes is 8 wt% to 20 wt%. [4] A method for charging raw materials into a vertical carbonization furnace according to any one of [1] to [3], characterized in that the gas is air or nitrogen gas, and the injection speed of the gas into the furnace is 7 m / s to 25 m / s. [5] A method for charging raw materials into a vertical carbonization furnace according to any one of [1] to [4], characterized in that the angle θ of injection of the gas into the furnace is 90° to 135° with respect to the inclined surface of the charging port. [6] A raw material charging device for a vertical carbonization furnace, having a charging port for charging raw materials, characterized in that the charging port is equipped with a gas injection device for dispersing fine particles in the raw material. [7] The raw material charging device for a vertical carbonization furnace according to [6], wherein the raw material is a briquette raw material and the particle diameter of the fine particles is 15 mm or less. [8] The raw material charging device for a vertical carbonization furnace according to [6] or [7], wherein the weight ratio of the fine particles in the briquette raw material is 8 wt% to 20 wt%. [9] A raw material charging device for a vertical carbonization furnace according to any one of [6] to [8], characterized in that the gas is air or nitrogen gas, and the injection speed of the gas into the furnace is 7 m / s to 25 m / s.

[10] A raw material charging device for a vertical carbonization furnace, in any one of [6] to [9], characterized in that the injection angle θ of the gas into the furnace is 90° to 135° with respect to the inclined surface of the charging port. [Effects of the Invention]

[0012] The present invention enables the raw materials to be uniformly charged in the depth direction of a vertical carbonization furnace without segregation of particle size when producing ferro-coke using the vertical carbonization furnace. As a result, the gas injection in the furnace is made uniform and the variation in carbonization temperature is reduced, thereby enabling the production of high-quality ferro-coke of uniform quality at low cost and improving productivity. [Brief explanation of the drawings]

[0013] [Figure 1]1 is a schematic cross-sectional view showing an example of an upper part of a vertical carbonization furnace according to the present invention. FIG. [Figure 2] 3 is a schematic cross-sectional view showing the injection angle of the injected gas into the furnace according to the present invention. FIG. [Figure 3] FIG. 1 is a schematic cross-sectional view showing an example of the furnace upper portion of a conventional vertical carbonization furnace. [Figure 4] This is a graph showing the relationship between the coarse particle and fine particle distribution ratio of the burden material in the furnace depth direction, and is an example when the fine particle weight ratio is 8%. [Figure 5] This is a graph showing the relationship between the coarse particle and fine particle distribution ratio of the burden material in the furnace depth direction, and is an example when the fine particle weight ratio is 20%. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, with reference to the drawings, embodiments of the raw material charging method and raw material charging device for a vertical carbonization furnace according to the present invention will be described in detail, but the present invention is not limited to these. Furthermore, since the drawings are intended to conceptually explain the present invention, the dimensions and ratios of the various components shown may differ from the actual dimensions.

[0015] [Vertical carbonization furnace] The vertical carbonization furnace that is the subject of the present invention has a charging zone at the top where the molded material is charged, a carbonization zone in the middle consisting of a low-temperature heating section and a high-temperature heating section, a cooling zone below that, and a discharge zone at the bottom for the produced molded coke.

[0016] Here, the briquette raw material is a mixture of carbon-containing materials (e.g., coal) and iron-containing materials (e.g., iron ore), which are the raw materials for briquette coke (ferro-coke), in a predetermined ratio, to which a binder is added and then briquette is formed into a block. Examples of binders for briquette include soft pitch (SOP), asphalt pitch (ASP), starch, and direct coal liquefaction residue. The binder is preferably added in a weight ratio of 1 wt% to 15 wt% of the carbon-containing material (e.g., coal). If the binder is added in a ratio of less than 1 wt%, the binder will not penetrate the coal surface sufficiently, making it difficult to obtain sufficient strength. If the binder is added in a ratio of more than 15 wt%, the manufacturing cost will increase significantly, which is undesirable. A more preferred ratio is 3 wt% to 10 wt%.

[0017] FIG. 3 is a schematic diagram showing a cross section of the charging zone in the upper furnace section 1 of a conventional vertical carbonization furnace. Briquettes 5 produced through a briquette production process are stored in a storage tank (not shown) and then introduced into the upper furnace section 1 through a charging port 3 via a charging chute 2. A gate 4 is provided just before the outlet of the charging port 3. By closing the gate 4, an appropriate amount of briquettes 5 (for one batch) can be stored. By opening the gate 4, the briquettes 5 can be introduced into the furnace via the inclined charging chute 2. Here, the raw material charging device 9 refers to the overall configuration from the charging chute 2 to the charging port 3.

[0018] The furnace is designed so that raw materials are stored up to the vicinity of the charging port 3, and the charged raw materials fall onto the stored raw materials (charge material 8) near the midpoint in the depth direction. In addition, a gas outlet 6 for discharging gas from inside the furnace is provided near the top of the upper furnace part 1, and the pressure inside the furnace is controlled by adjusting the exhaust gas 7. After the raw materials are charged and stored in this vertical carbonization furnace, gases (low-temperature gas, high-temperature gas, and cooling gas) are circulated through multiple tuyeres in the carbonization zone at the bottom, allowing for efficient heating during carbonization and subsequent cooling.

[0019] While the cross-sectional view of the vertical carbonization furnace shown in Figure 3 is taken from the raw material charging side toward the depth, a cross-sectional view perpendicular to the cross-section is not shown. However, the width perpendicular to the depth (furnace width) is designed to be long because the depth cannot be increased. The shape of the furnace upper section 1 is, for example, 1.0 m to 2.0 m deep and 4 m to 8 m wide. Therefore, multiple rows of charging chutes 2 are installed at equal intervals (for example, 0.8 m to 1.2 m intervals) across the furnace width, and each charging inlet 3 is provided with a gate 4. The shape of the charging chutes 2 is not particularly limited, and examples include a square pillar with a rectangular cross section or a cylindrical shape with a circular cross section.

[0020] [Particle size composition of molded product] Next, the particle size distribution of the shaped product and particle size segregation of the charged material will be explained. When the briquettes are transported to the vertical dry distillation furnace after the briquettes production process, they are partially crushed and disintegrated to produce fine particles. The size (particle size) of the briquettes immediately after production is 20 mm to 30 mm on average, but many fine particles are present before they are placed inside the furnace. Here, in the present invention, particles with a particle size of 15 mm or less are defined as "fine particles" and particles with a particle size of more than 15 mm are defined as "coarse particles." The weight ratio of the fine particles (ratio of the weight of the fine particles to the weight of the entire briquettes raw material) is 8 wt% to 20 wt%. This numerical range is based on the minimum and maximum values ​​of actual measurements.

[0021] Furthermore, even if the raw materials are charged so that they are directed towards the middle of the furnace, the fine particles tend to fall before the middle part without reaching it, which causes particle size segregation of the charged materials and has an adverse effect on gas injection in the carbonization zone, etc.

[0022] [Gas injection] Therefore, the present inventors have conducted research to eliminate variations in the fine particles of the raw material being fed, and have discovered a method of preventing the fine particles from falling unevenly by injecting gas into the raw material being fed. That is, the present invention is characterized in that a gas injection device 10 is provided near the furnace outlet of the charging port 3 in the upper part of the furnace 1, as shown in FIG.

[0023] Here, the injection speed of the gas 11 injected in the depth direction when charging the raw materials is preferably 7 m / s to 25 m / s. By adjusting it to this range, the charging tendency of the shaped material (described later) remains unchanged, and the charging tendency of the fine granules mixed with the shaped material can be uniformly dispersed in the depth direction. More preferably, it is 15 m / s to 20 m / s.

[0024] As the gas 11 to be sprayed, it is preferable to use air or nitrogen gas. This gas injection prevents the segregation of fine particles toward the charging port side, and by uniformly blowing gas into the vertical carbonization furnace, it is possible to reduce variations in the carbonization temperature and produce high-quality, uniform ferro-coke at low cost. Specific examples of the gas injection device 10 include a blower and a compressor. Furthermore, the specific installation position of the gas injection device 10 is the charging port 3, and particularly preferably near the outlet of the furnace. More preferably, it is located below the furnace outlet of the charging port 3, near the boundary with the furnace inner wall.

[0025] As shown in Figure 2, the injection angle θ of the gas injection direction is preferably 90° or more, i.e., in the direction toward the furnace interior from the perpendicular to the inclined surface 12 of the charging inlet 3. This is because an injection angle θ of less than 90° results in a reverse flow relative to the direction of raw material charging. Furthermore, if the injection angle θ is 45° in the direction toward the furnace interior from the perpendicular to the inclined surface 12 of the charging inlet 3, i.e., exceeds 135°, the dispersion effect of fine particles becomes poor. Therefore, the injection angle θ of the gas into the furnace is preferably 90° to 135° relative to the inclined surface of the charging inlet. More preferably, it is 95° to 120°.

[0026] The inclined surface 12 of the charging port 3 has an angle δ with respect to the vertical side wall 13 of the vertical carbonization furnace, and this angle δ is the angle at which the raw material is charged into the furnace, and is preferably 30° to 70°, and more preferably 40° to 60°. [Example]

[0027] Hereinafter, the embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0028] In order to confirm the effects of the present invention, a charging test was conducted simulating the operation of a vertical carbonization furnace. In the charging test, a charging model simulating the shape of the charging inlet 3 of the furnace upper part 1 shown in Figure 1, in which a gas injection device 10 was installed, was used, and the dimensions of the furnace upper part 1 into which the charge material descends were set to a width of 0.3 m, a depth of 1.5 m, and a height from the charging inlet 3 to the charge material 8 of 1.0 m.

[0029] A variable-speed air blower (gas injection device 10) was installed near the furnace exit of the charging inlet 3, and coarse granules (grain size: over 15 mm) and fine granules (grain size: 15 mm or less) were mixed and charged. Air was used as the gas, and the air injection speed was varied from 0 m / s (i.e., no air injection), 7 m / s, 15 m / s, 20 m / s, and 25 m / s. Tests were conducted with a fine granule weight ratio (ratio of fine granules to total granule weight) of 8 wt% (minimum) to 20 wt% (Tests No. 1 to 10). The gas injection angle θ was set at 105° upward with respect to the inclined surface 12 of the charging inlet 3 (angle δ relative to the furnace sidewall 13 was 60°).

[0030] Table 1 shows the comparison conditions for the above charging tests.

[0031] [Table 1]

[0032] After the charging test, samples were taken from 10 equally spaced locations in the depth direction from the front to the opposite side (scattering locations shown in Figures 4 and 5 below). The coarse particle abundance rate (the ratio of the coarse particle weight at each location to the total coarse particle weight) and the fine particle abundance rate (the ratio of the fine particle weight at each location to the total fine particle weight) at each of the 10 locations were compared.

[0033] The results are shown in Figures 4 and 5. Figure 4 shows the case where the fine particle weight ratio was 8 wt%, the lowest actually measured value, and Figure 5 shows the case where the fine particle weight ratio was 20 wt%, the highest actually measured value.

[0034] From these results, in the present invention example, regardless of whether the weight ratio of fine particles with a particle size of 15 mm or less was a minimum of 8 wt% or a maximum of 20 wt%, it was possible to shift the falling position of the fine particles to the center position in the depth direction (the middle part of the furnace) when the air injection speed was 7 m / s to 25 m / s. In particular, since the falling position of the fine particles was closer to the center position at an air injection speed of 7 m / s and the influence of air injection on the coarse particles began to be felt at 25 m / s, it was found that an air injection speed of 7 m / s to 25 m / s was the appropriate condition. It was found that by injecting air within this range, the fine particles could be uniformly mixed throughout the charge, and high-quality molded coke could be obtained.

[0035] From the above, the effectiveness of the present invention was confirmed. [Explanation of symbols]

[0036] 1 Upper part of furnace 2 Charging chute 3 charging port 4 Gates 5 Molded object 6 Gas outlet 7. Exhaust gas 8 Charge 9 Raw material charging device 10 Gas Injector 11 Propellant gas 12 Inclined surface (at the loading entrance) 13 Furnace side wall θ Gas injection angle δ Angle of inclined surface

Claims

1. A method for charging raw materials into a vertical carbonization furnace, characterized in that when the raw materials are charged into the vertical carbonization furnace through a charging port, the inclined surface of the charging port has an angle δ of 30° to 70° with respect to the vertical side wall of the vertical carbonization furnace, and gas is injected into the raw materials at the charging port at an injection angle θ of 90° to 135° with respect to the inclined surface of the charging port into the furnace, thereby dispersing fine particles in the raw materials.

2. 2. The method for charging raw materials into a vertical carbonization furnace according to claim 1, wherein the raw material is a briquette raw material and the fine particles have a particle size of 15 mm or less.

3. 3. The method for charging raw materials into a vertical dry distillation furnace according to claim 2, wherein the weight ratio of the fine particles in the raw material for forming the briquettes is 8 wt % to 20 wt %.

4. A method for charging raw materials into a vertical carbonization furnace according to any one of claims 1 to 3, characterized in that the gas is air or nitrogen gas, and the injection speed of the gas into the furnace is 7 m / s to 25 m / s.

5. A raw material charging device for a vertical carbonization furnace, having a charging port for charging raw materials, characterized in that the charging port is equipped with a gas injection device for dispersing fine particles in the raw material, the inclined surface of the charging port has an angle δ of 30° to 70° with respect to the vertical side wall of the vertical carbonization furnace, and the injection angle θ of the gas into the furnace is 90° to 135° with respect to the inclined surface of the charging port.

6. 6. The raw material charging device for a vertical carbonization furnace according to claim 5, wherein the raw material is a briquette raw material and the fine particles have a particle size of 15 mm or less.

7. 7. The raw material charging device for a vertical dry distillation furnace according to claim 6, wherein the weight ratio of the fine particles in the briquette raw material is 8 wt % to 20 wt %.

8. A raw material charging device for a vertical carbonization furnace as described in any one of claims 5 to 7, characterized in that the gas is air or nitrogen gas, and the injection speed of the gas into the furnace is 7 m / s to 25 m / s.

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