Processing method of filler layer accomodated in tubular container

Abstract

Provided is a processing method of a filler layer enabling suppression of fluidization of filler particles. This processing method of a filler layer accommodated in a tubular container is characterized in that a step of supplying a first gas into the tubular container from a nozzle provided on a side part of the tubular container in a state in which the filler layer is accommodated in the tubular container is performed under a condition satisfying the following formula (1).　(1): DT / DP ≤ 12 × (Pinj / Ph)-0.21, where DT is the length (m) in the vertical direction of a nozzle port of the nozzle, DP is the harmonic mean particle diameter (m) of all the filler particles constituting the filler layer, Pinj is the impact wind pressure (Pa) in the horizontal direction of the first gas at the height position of the nozzle, and Ph is the powder pressure (Pa) in the horizontal direction of the filler layer at the height position of the nozzle.

Description

Method for treating a packed bed contained in a cylindrical container

[0001] The present invention relates to a method for treating a packed bed contained in a cylindrical vessel, including a blast furnace.

[0002] In recent years, CO, one of the greenhouse gases, ２ There is a growing movement to reduce CO2 emissions, and it is becoming urgent to reduce the use of coal-derived reducing agents in blast furnace operations. The reducing agent has two roles: it generates heat in the furnace to raise the temperature of the charge materials, and it reduces the iron-based raw materials (iron ore, sintered iron ore, iron ore pellets, etc.) in the furnace. ２ Hydrogen is attracting attention as a reducing agent with the aim of reducing gas emissions. The reduction rate with hydrogen is faster than that with CO gas, so by injecting hydrogen-based reducing gas into a blast furnace, CO ２ It is possible to simultaneously reduce gas emissions and increase reduction efficiency.

[0003] Because the reduction of iron-based raw materials with hydrogen is an endothermic reaction, there has been a problem in that the temperature rise of the charge material in the blast furnace is delayed, preventing smooth reduction. Furthermore, when high-temperature gas is injected from the shaft to prevent insufficient temperature rise of the charge material, the particle-packed bed of the charge material becomes fluidized, destabilizing the descent of the charge material. Therefore, an operation method has been disclosed for avoiding the influence of insufficient temperature rise of the charge material in the upper part of the furnace while preventing fluidization of the packed particles constituting the packed bed. Patent Document 1 discloses a method for operating a blast furnace in which hot air having an oxygen enrichment rate of 20% by volume or less is injected into the blast furnace from a tuyere and preheat gas is injected from a preheat gas injection section at a predetermined position. Patent Document 2 discloses a method for operating a blast furnace in which, when shaft gas is injected from the shaft of the blast furnace, the flow velocity of the shaft gas is set to 100 m / s or less.

[0004] As will be described later, Non-Patent Document 1 discloses a method for measuring the internal friction angle of powder, Non-Patent Document 2 discloses a method for measuring the wall friction angle of powder, and Non-Patent Document 3 discloses the configuration of a blast furnace simulation model.

[0005] JP 2011-149085 A JP 2011-231350 A

[0006] Ryuichi Aoki, "Method for Measuring the Angle of Repose and the Angle of Internal Friction of Powders," Journal of Powder Technology Research Association, Vol. 6, No. 1, 1969, pp. 3-8; Ryuichi Aoki, "On the Friction Angle of Powders," Chemical Engineering, Vol. 24, No. 8, 1960, pp. 598-600; Sato et al., Kawasaki Steel Technical Report, Vol. 29 (1997), pp. 30-36

[0007] However, in Patent Documents 1 and 2, fluidization is suppressed by focusing only on the gas flow velocity of the shaft gas injection nozzle (hereinafter also referred to as SGI nozzle), and the influence of other blast furnace conditions, such as the shape of the SGI nozzle or the properties of the packed particles that make up the packed bed, is not fully considered. Therefore, even if the gas flow velocity is controlled by applying the method of Patent Documents 1 or 2 to a packed bed whose conditions are significantly different from those of Patent Documents 1 or 2, it is expected that the packed particles will fluidize, and there is room for improvement.

[0008] In view of the above problems, the present invention aims to provide a method for treating a packed bed that can suppress fluidization of packed particles even when gas is supplied from the side of the container to a packed bed under various conditions.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems and have found the following: Ｔ , the harmonic mean particle diameter D of all packed particles constituting the packed bed Ｐ , the horizontal blast pressure P of the gas supplied from the nozzle at the height position of the nozzle ｉｎｊ , and the horizontal powder pressure P of the packed bed ｈ By satisfying the predetermined relationship among the four parameters, the fluidization of the packed particles can be suppressed. ｉｎｊ and P ｈ can be calculated by a predetermined formula from the characteristic values ​​of the packed particles and the characteristic values ​​of the gas blown from the nozzle.

[0010] That is, the gist and configuration of the present invention are as follows.

[0011] [1] A method for treating a packed bed contained in a cylindrical container, the method comprising: supplying a first gas into the cylindrical container from a nozzle provided on the side of the cylindrical container while the packed bed is contained in the cylindrical container, under conditions that satisfy the following formula (1): Ｔ / D Ｐ ≦12×(P ｉｎｊ / P ｈ ) －０．２１ ... (1) where, D Ｔ D: Vertical length of the nozzle opening of the nozzle (m) Ｐ P: harmonic mean particle size (m) of all packed particles constituting the packed layer ｉｎｊ : horizontal blast pressure (Pa) of the first gas at the height position of the nozzle ｈ : horizontal powder pressure (Pa) of the packed bed at the height position of the nozzle.

[0012] [2] The blast pressure P ｉｎｊ and the powder pressure P ｈ The method for treating a packed bed according to the above [1], wherein is calculated based on the following formulas (2) to (5): Here, A ＢＦ : Area (m) of the horizontal cross section of the cylindrical container at a height position intermediate between the nozzle and the upper surface of the packed bed ２ ) P ＢＦ ρ: perimeter (m) of the horizontal cross section of the cylindrical container at a height position midway between the nozzle and the top surface of the packed bed; h: distance (m) from the height position of the nozzle to the height position of the top surface of the packed bed; ｐ : Average bulk density of all the packed particles (kg / m ３ ) ε: average void ratio of the packed bed (-) φ ｉ : average internal friction angle of all the packed particles (°) k: average active powder pressure coefficient of all the packed particles (-) x: penetration distance of the first gas (m) c ｗ : Wall friction coefficient (-) of all the packed particles ｈ : horizontal gas flow velocity of the nozzle (m / s) u ｖρ: Vertical upward gas flow velocity (m / s) in the cylindrical container at the height position of the nozzle ｓｇｉ : density of the first gas (kg / m ３ ) μ ｓｇｉ ρ: viscosity of the first gas (Pa s) ｂｆ : average gas density (kg / m) in the cylindrical container ３ ) μ ｂｆ : average gas viscosity in the cylindrical container (Pa s) f: average shape factor of all the packed particles (-) g: gravitational acceleration (m / s ２ g': apparent gravitational acceleration in the cylindrical container (m / s ２ )

[0013] [3] The packed bed treatment method described in [1] or [2] above, wherein a second gas rising within the cylindrical container is generated by supplying gas from a supply port provided at the bottom of the cylindrical container.

[0014] [4] The packed bed treatment method according to any one of [1] to [3] above, wherein the cylindrical vessel is a blast furnace.

[0015] According to the method for treating a packed bed of the present invention, fluidization of the packed particles can be suppressed when gas is supplied to the packed bed from the side of the container.

[0016] It is a schematic diagram of a cylindrical vessel used in the examples of the present invention. It is a schematic diagram of a method of operating a blast furnace when the cylindrical vessel is a blast furnace in one embodiment of the present invention. Ｔ / D Ｐ and P ｉｎｊ / P ｈ This is a graph showing the relationship between the D and the calculation results when the present invention is applied to a blast furnace. Ｔ / D Ｐ and P ｉｎｊ / P ｈ 1 is a graph showing the relationship between

[0017] Hereinafter, an embodiment of the method for treating a packed bed contained in a cylindrical container according to the present invention will be described. Note that the embodiment described below is an example of the present invention, and the configuration of the present invention is not limited to this specific example.

[0018] It is generally known that physical phenomena can be described as generalized phenomena applicable to a wide range of targets, independent of equipment size, physical properties, and operating conditions (e.g., flow rate, temperature, pressure, etc.), by using appropriately non-dimensional parameters rather than specific physical quantities themselves (e.g., gas flow rate, nozzle diameter, etc.). This is called the law of similarity, and is an evaluation method often used when reproducing large-scale equipment such as blast furnaces, which are difficult to measure, using cold scale models. Based on the results of various experiments using a cylindrical vessel, the inventors investigated whether it would be possible to describe the fluidization phenomenon of packed particles using non-dimensional parameters independent of equipment scale, particle properties, gas properties, operating conditions, etc.

[0019] In the present invention, the state in which the packed particles are fluidized is defined as follows: When gas is blown into a packed bed from a nozzle attached to a cylindrical vessel, the packed particles are stationary when the gas flow rate is low, but as the gas flow rate is increased, the packed particles begin to move. In the present invention, the innermost region of the cavity formed in front of the nozzle opening in the cylindrical vessel (hereinafter also referred to as the fluidization depth) is determined as the harmonic mean particle diameter D of the packed particles, which will be described later. Ｐ The state where the packed particles are fluidized is when the fluidization depth reaches three times or more of the harmonic mean particle diameter D Ｐ When the fluidization depth is more than three times the harmonic mean particle diameter D, the packed particles located above and below are replaced more vigorously, which increases the possibility of the structure of the packed bed collapsing. In a packed bed where packed particles descend uniformly, such as in a blast furnace, the replacement of packed particles located above and below destabilizes the descent of the packed particles and has a negative effect on operation. Therefore, the fluidization depth is determined by the harmonic mean particle diameter D Ｐ It is necessary to maintain the particle size at less than three times the normal size. In the state where the packed particles are fluidized, it is assumed that the packed particles are rotating as in the raceway in front of the tuyere of a blast furnace, but the present invention is not limited to such a case.

[0020] After extensive research, the inventors have newly discovered that the fluidization phenomenon of packed particles occurs when the horizontal blast pressure of the first gas at the nozzle height position is significantly greater than the horizontal powder pressure of the packed bed at the nozzle height position. In addition to the above, they have also found that the fluidization behavior is affected not only by the flow rate of the first gas injected from the nozzle on the side of the container, but also by the vertical length of the nozzle opening of the nozzle that injects the first gas. Based on this, they have investigated conditions applicable to a wide variety of packed particles and discovered that it is possible to prevent the fluidization of packed particles by treating the packed bed under conditions that satisfy the following formula (1): D Ｔ / D Ｐ ≦12×(P ｉｎｊ / P ｈ ) －０．２１ ... (1) where, D Ｔ D: Vertical length of the nozzle opening of the nozzle (m) Ｐ P: harmonic mean particle size (m) of all packed particles constituting the packed layer ｉｎｊ : horizontal blast pressure of the first gas at the height position of the nozzle (Pa) P ｈ : horizontal powder pressure (Pa) of the packed bed at the height position of the nozzle

[0021] In addition, D in the above formula (1) Ｔ / D Ｐ The lower limit of D is not particularly limited, but in order to prevent the pressure loss in the nozzle from becoming too high, Ｔ / D Ｐ is preferably 1 or more.

[0022] In the above formula (1), for reasons such as g' being a negative value, which will be described later, P ｉｎｊ / P ｈ When P is less than 0, the right side of formula (1) is not a real number, and the packed bed treatment cannot be performed under the condition that formula (1) is satisfied. In other words, such a case does not satisfy the provisions of the present invention and is outside the scope of the present invention. In addition, in order to supply the first gas into the cylindrical container from the nozzle, P ｉｎｊ / P ｈ It is not possible to imagine a case where P ｉｎｊ / P ｈis greater than 0, and preferably 0.1 or more. ｉｎｊ / P ｈ There is no particular upper limit to P ｉｎｊ / P ｈ is generally less than 1000.

[0023] [Cylindrical Container] The configuration of the cylindrical container, which is a prerequisite for satisfying the above formula (1), will be described below.

[0024] The cylindrical container used in one embodiment of the present invention accommodates a packed bed inside, has a supply port at the bottom, and a nozzle on the side. Figure 1 shows a schematic diagram of the cylindrical container 100 used in the examples of the present invention. With the packed bed 10 accommodated inside the cylindrical container 100, a first gas 14 is supplied into the cylindrical container 100 through a nozzle 12 provided on the side of the cylindrical container 100. Alternatively, a gas may be blown into the cylindrical container 100 through a supply port 16 provided at the bottom of the cylindrical container 100 to generate a second gas 18 that rises within the cylindrical container. During processing, a vibrating feeder 20 installed at the bottom of the cylindrical container 100 extracts 22 the packed particles that make up the packed bed 10 at a constant speed, lowering the raw material particles. At this time, the height of the packed bed 10 can be maintained constant by periodically replenishing 24 the packed particles from the top of the cylindrical container 100.

[0025] The maximum height of the packed bed 10 contained within the cylindrical container 100 is defined as a reference height, and the nozzle 12 is installed at a position lower than the reference height. The value obtained by dividing the distance from the reference height to the installation height of the nozzle 12 by the distance from the reference height to the position of the supply port 16 is preferably 0.1 or greater and 0.9 or less. Setting this value to 0.1 or greater can effectively prevent the packed particles on the surface of the packed bed 10 from fluidizing and blowing through. On the other hand, setting this value to 0.9 or less can effectively prevent the first gas 14 from being introduced before the second gas 18 reaches the furnace wall of the cylindrical container 100. The cylindrical container 100 is preferably installed so that its height axis is parallel to the vertical direction. The cross-sectional shape of the cylindrical container is not particularly limited, and a cylindrical container with a cylindrical cross section, for example, can be used.

[0026] An example of a cylindrical vessel having such a structure is a blast furnace. The cylindrical vessel used in one embodiment of the present invention is preferably a blast furnace. Conditions for applying the present invention to a blast furnace will be described later. Note that the present invention can be applied to any case where treatment is performed using a shaft furnace or the like having a structure in which gas is injected from the side and bottom of the cylindrical vessel, other than a blast furnace.

[0027] Figure 2 shows a schematic diagram of a method for operating a blast furnace in one embodiment of the present invention, where the cylindrical vessel is a blast furnace. The interior of the blast furnace 102 is filled with raw material particles 30, an SGI nozzle 32 is provided in the shaft, and a tuyere 34 is provided in the lower part for injecting oxygen-containing gas and a reducing agent. In operation of the blast furnace 102, the first gas is SGI gas 36 supplied from the SGI nozzle 32, and the second gas is bosh gas 38 rising within the blast furnace from the lower part. Furthermore, molten iron 40 can be removed from the bottom of the blast furnace 102 during processing.

[0028] The packing particles constituting the packed layer contained inside the cylindrical container can be appropriately selected by the practitioner depending on the type and application of the cylindrical container. The packed layer may be composed of multiple types of packing particles.

[0029] When the cylindrical vessel is a blast furnace, the packed bed can be made of iron-based raw materials (iron ore, sintered iron ore, iron ore pellets, reduced iron, etc.) and reducing materials (coke, etc.). The particle size of the raw materials constituting the packed bed is appropriately selected according to the size of the cylindrical vessel. For example, in a blast furnace with a height of 10 m and an inner diameter of 3 m, the average particle size can be 10 mm or more and 50 mm or less. Furthermore, when the cylindrical vessel is a blast furnace, the average bulk density of the packed bed can be 500 kg / m ３ More than 1810kg / m ３ It is preferable that:

[0030] [First Gas and Second Gas] Air or the like can be used as the first gas supplied to the cylindrical container from a nozzle (described later) and the second gas rising inside the cylindrical container. From the viewpoint of preventing condensation from forming in the packed bed, the temperatures of the first gas and the second gas are preferably high enough to prevent condensation, for example, 15°C or higher. Furthermore, from the viewpoint of protecting the device, the temperature of the first gas is preferably below the heat-resistant temperature of the device, for example, 60°C or lower when the cylindrical container is made of PVC.

[0031] When the cylindrical vessel is a blast furnace, granular raw ore and coke are charged into the blast furnace from the top, and an oxygen-containing gas and an injection reducing agent (methane gas, etc.) are injected into the blast furnace from tuyere 34 provided in the bottom. When the present invention is applied to a blast furnace, the second gas is a gas (hereinafter also referred to as bosh gas) that reduces the raw ore while rising inside the furnace from the bottom, and the first gas is a high-temperature gas (hereinafter also referred to as SGI gas) injected from a nozzle (SGI nozzle 32) provided in the blast furnace shaft.

[0032] The SGI gas preferably contains at least one of carbon monoxide and hydrogen from the viewpoint of not inhibiting the reduction reaction of the iron-based raw materials in the blast furnace. Furthermore, since it is necessary to supply gas from the nozzle at a temperature equivalent to that of the bosh gas when it rises to the nozzle position, the temperature of the SGI gas is preferably 400°C or higher. Furthermore, from the viewpoint of preventing energy loss due to overheating of the gas temperature, the temperature of the SGI gas is preferably 1200°C or lower, and more preferably 1000°C or lower.

[0033] The blast gas supplied to the tuyere of the blast furnace is an oxygen-containing gas such as air or oxygen. ２ From the viewpoint of reducing gas emissions, the blown gas is preferably oxygen. ２ From the viewpoint of reducing gas emissions, the reducing agent blown through the tuyere is preferably a hydrogen-based reducing gas such as methane. From the viewpoint of ensuring a constant gas temperature at the tip of the tuyere, the temperature of the gas supplied to the tuyere is preferably 0°C or higher. Furthermore, from the viewpoint of preventing an excessive temperature rise of the gas at the tip of the tuyere, the temperature of the gas supplied to the tuyere is preferably 1300°C or lower.

[0034] Bosh gas is a reducing gas (CO, H) generated when the blast gas and the injected reducing agent supplied to the tuyere of the blast furnace react with the coke at the tip of the tuyere in the raceway. ２ , N ２ In order to promote the reduction reaction of the ore, the temperature of the bosh gas at the nozzle height is preferably 560°C or higher. In addition, in order to prevent the softened and molten ore from adhering to the nozzle, the temperature of the bosh gas at the nozzle height is preferably 1200°C or lower.

[0035] [Nozzles] Next, the nozzles provided on the side of the cylindrical container will be described. If the number of nozzles provided on the side of the cylindrical container is one or more, it is possible to preferably maintain the amount of the first gas injected while preferably suppressing fluidization of the packed particles. On the other hand, if the number of nozzles is 100 or less, it is possible to preferably reduce equipment costs and maintenance costs and operate efficiently. Therefore, the number of nozzles is preferably 100 or less, and more preferably 50 or less. Note that when multiple nozzles are installed, it is preferable that the nozzles installed at the same height position on the side of the cylindrical container are installed so as to be evenly spaced around the cylindrical container. The same applies when the nozzles are installed in multiple stages in the vertical direction, as described below.

[0036] Furthermore, the nozzle does not necessarily have to be arranged horizontally, but may be arranged at an angle to the side of the cylindrical container. When the nozzle is arranged at an angle to the side of the cylindrical container, the nozzle height position is defined as the height of the nozzle tip.

[0037] Furthermore, when multiple nozzles are installed, all of the nozzles may be installed at the same height position, but it is not necessary for all of the nozzles to be installed at the same height position, and the nozzles may be arranged in multiple stages. For example, the nozzles may be arranged in a staggered arrangement of two or more stages. When the nozzles are arranged in multiple stages, the present invention is applied to each nozzle. Then, if the present invention is satisfied for all of the nozzles, it is determined that fluidization has not occurred.

[0038] The cross-sectional shape of the nozzle orifice perpendicular to the gas ejection direction (i.e., the nozzle orifice shape) is not limited to a circle, and may be, for example, a rectangle. Regardless of the shape, the maximum length of the nozzle orifice in the perpendicular direction is D Ｔ An example of a rectangular nozzle opening is one in which the nozzle tip is slit-shaped, and there may be multiple slits. The nozzle is not limited to a single-hole nozzle, and a multi-hole nozzle may also be used. As a multi-hole nozzle, a nozzle having multiple discharge holes arranged at equal intervals and close to each other can be used. For example, a nozzle in which multiple holes are formed by bundling multiple pipes, a nozzle tip with multiple holes attached to the tip of a single pipe, or a single-hole nozzle with multiple holes formed by attaching a net to the nozzle, etc. can be used. In addition, when a multi-hole nozzle is used, the vertical length D of the nozzle opening Ｔ is the length in the vertical direction from the bottom end of the lowest nozzle to the top end of the highest nozzle among the multiple ejection holes of the multi-hole nozzle. Furthermore, when a multi-hole nozzle is used, the effect of preventing the intrusion of filler particles into the nozzle is obtained. Note that when multiple nozzles are installed, the cross-sectional shapes of the nozzles may be different for each nozzle, but it is preferable that all nozzles have the same cross-sectional shape. Furthermore, when the cross-sectional shapes of the nozzles are different, the present invention is applied to each nozzle. Then, when the present invention is satisfied for all nozzles, it is determined that no fluidization has occurred.

[0039] [D Ｔ ] The vertical length D of the nozzle opening of the nozzle Ｔ D Ｐ If this is the case, the first gas is suitably diffused while the pressure loss in the nozzle is kept low. Ｔ is D Ｐ For example, D Ｐ If is 0.02 m, D Ｔ On the other hand, D Ｔ D Ｐ When the diameter is 10 times or less, backflow of the packed particles in the packed bed to the nozzle can be suitably prevented. Ｔ is D Ｐ Preferably, it is 10 times or less of D ＰFor example, the harmonic mean particle diameter D of all packed particles is preferably 5 times or less. Ｐ If is 0.02 m, D Ｔ is preferably 0.20 m or less, and more preferably 0.10 m or less.

[0040] The above formula (1) is based on the D Ｔ It is preferable to use it when determining D Ｔ If it is difficult to adjust Ｐ , P ｉｎｊ , and P ｈ The operating conditions may be determined by adjusting the above.

[0041] [D Ｐ ] Harmonic mean particle diameter D of all packed particles constituting the packed bed Ｐ When the distance is 0.001 m or more, the airflow resistance of the packed bed can be kept low, and the gas can be stably passed through without causing fluidization or blow-through of the packed particles. Ｐ On the other hand, D Ｐ When the distance D is 0.050 m or less, the heat transfer and reaction between the gas and the packed particles can proceed without delay. Ｐ is preferably 0.050 m or less.

[0042] The harmonic mean particle size D of all packed particles constituting the packed bed Ｐ can be determined as follows: First, 1 kg of a powder sample of particles to be filled into a cylindrical container is collected and dried. Next, the powder sample is sieved using sieves with openings of 0.25, 0.5, 1, 2, 4, 8, 16, 31.5, 63, and 125 mm in order of increasing opening size, and the weight proportion of each particle size is measured. From the measurement results, the harmonic mean particle diameter D is calculated using the following equation (6): Ｐ Ask for. Here, i is an integer from 1 to 10, and the weight ratio of the i-th particle size range sieved by each sieve is w ｉ , the representative particle diameter is x ｉ Let's say.

[0043] In the above measurement, the representative particle diameter x of each particle size range ｉare the geometric mean of the larger and smaller mesh openings, respectively. Furthermore, in order to prevent fluidization of the packed particles, it is common to thoroughly remove fine powders with a particle size of 0.25 mm or less from the packed particles used in the packed bed in advance. Therefore, the amount of fine particles of 0.25 mm or less contained in the packed particles is small and can be ignored. Furthermore, for particles with a particle size of 125 mm or more, the geometric mean of 125 mm and the maximum particle size among the collected particles is used as the representative particle size. When the packed bed is composed of multiple particle types, the harmonic mean particle size of each particle type is measured, and a weighted average value is calculated based on the mixing ratio (bulk volume ratio) of each particle type in the packed bed, and the obtained average value is used as D ｐ Let's say.

[0044] [P ｉｎｊ ] Horizontal blast pressure P of the first gas at the height position of the nozzle ｉｎｊ When the pressure is 0.1 kPa or more, the effect of suppressing the intrusion of particles into the nozzle can be obtained. ｉｎｊ is preferably 0.1 kPa or more. ｉｎｊ When the pressure is 40,000 kPa or less, the pressure loss in the nozzle can be kept low. ｉｎｊ is preferably 40,000 kPa or less. ｉｎｊ Since it is difficult to directly calculate, it is preferable to use equation (2).

[0045] [P ｈ ] Horizontal powder pressure P of the packed bed at the height position of the nozzle ｈ When the pressure is 0.1 kPa or more, it is possible to suppress sudden blow-through due to fluctuations in the gas flow rate in the packed bed. ｈ is preferably 0.1 kPa or more. ｈ When the pressure is 50 kPa or less, the powdering of the particles constituting the packed bed can be suppressed. ｈ is preferably 50 kPa or less. ｈ Equation (3) may be used to directly measure P ｈ can also be measured.

[0046] As a result of further detailed investigation, the present inventors found that P ｈ and P ｉｎｊ This has enabled us to estimate more precisely, and we have established a method to predict with high accuracy whether fluidization of packed particles will occur. ｉｎｊ and P ｈ can be expressed by the following equations (2) and (3), respectively.

[0047] The definitions of the various coefficients used in equations (2) and (3) and how to obtain them will be described below.

[0048] [A ＢＦ The area of ​​the horizontal cross section of the cylindrical container at the height position midway between the nozzle and the top surface of the packed bed is A. ＢＦ (m ２ ) If the nozzles are installed in multiple stages in the height direction, A ＢＦ (m ２ In this case, the present invention is applied to each nozzle, and if the present invention is satisfied for all nozzles, it is determined that there is no fluidization. The same applies hereinafter.

[0049] [P ＢＦ ] The perimeter of the cylindrical container in the horizontal cross section at the height position midway between the nozzle and the top surface of the packed bed is P ＢＦ (m). If the nozzles are installed in multiple stages in the height direction, P ＢＦ (m) is obtained.

[0050] [h] The distance from the height position of the nozzle to the height position of the top surface of the packed bed is defined as h (m). If the top surface of the packed bed is not horizontal, the height position of the top surface of the packed bed on the wall surface above the nozzle is used. If the nozzles are installed in multiple stages in the vertical direction, h (m) is obtained for each nozzle.

[0051] [ρ ｐ ] The average bulk density of all the packed particles constituting the packed bed is ρ ｐ (kg / m ３ ) ρ ｐcan be calculated as follows: Packing particles are packed into a container having a size sufficiently larger than the average particle size of the packed particles (for example, the inner diameter and height are each about 20 times the harmonic mean particle size of the packed particles). The weight of the packed particles is measured, and the value obtained by dividing the weight of the packed particles by the internal volume of the container is ρ ｐ When the packed bed is composed of multiple particle types, the bulk density of each particle type is measured as described above, and a weighted average value is calculated based on the mixing ratio (bulk volume ratio) of each particle type in the packed bed. The average value obtained is defined as ρ ｐ Let's say.

[0052] [ε] The average void ratio of the packed bed is defined as ε(-). ε can be determined as follows. First, the apparent density ρ of the packed particles is measured by a liquid weighing method or the like. When the packed bed is composed of a plurality of particle species, the apparent density of each particle species is measured, and a weighted average value is determined based on the mixing ratio of each particle species in the packed bed (apparent volume ratio, apparent volume ratio of each particle species = weight of each particle species in the packed bed / apparent density of each particle species), and the obtained average value is defined as ρ. Next, the obtained ρ and the above ρ ｐ Then, ε is calculated using the following equation (7): ε = 1 - ρ ｐ / ρ (7)

[0053] [φ ｉ ] The average internal friction angle of all packed particles constituting the packed bed is φ ｉ (°). ｉ can be measured using a shear tester described in Non-Patent Document 1. When the packed bed is composed of a plurality of particle types, the internal friction angle of each particle type is measured, and a weighted average value is calculated based on the mixing ratio (bulk volume ratio) of each particle type in the packed bed, and the obtained average value is used as φ ｉ Let's say.

[0054] [k] The average active powder pressure coefficient of all packed particles constituting the packed bed is k. k is the coefficient of the average active powder pressure of all packed particles constituting the packed bed. ｉ can be obtained from the following equation (4) using

[0055] [x] The upper limit of the penetration distance of the first gas is x (m). x is the harmonic mean particle diameter D ＰThe state in which the packed particles are fluidized is as described above.

[0056] [c ｗ ] The average wall friction coefficient of all packed particles constituting the packed bed is c ｗ (-). ｗ The wall friction angle φ can be calculated as follows: ｗ is calculated, and the wall friction coefficient c is calculated using the following equation (8). ｗ When the packed bed is composed of multiple particle types, the wall friction coefficient of each particle type is calculated, and a weighted average value is calculated based on the mixing ratio (bulk volume ratio) of each particle type in the packed bed. ｗ Let us assume that: ｗ = tan(φ ｗ ) ... (8)

[0057] [u ｈ ] The horizontal gas flow velocity of the nozzle is u ｈ (m / s). ｈ can be calculated as follows: The gas flow rate V of the first gas injected into each nozzle １Ｎ (Nm ３ / h) is corrected by the blowing temperature and pressure of the first gas to obtain the temperature and pressure corrected flow rate V １ Calculate the temperature and pressure corrected flow rate V １ Dividing by the cross-sectional area of ​​the nozzle opening gives u ｈ Calculate the temperature and pressure corrected flow rate V １ (m ３ / h) is specifically the gauge pressure P of the first gas at the nozzle position １ (PaG) and gas temperature T １ (°C) can be calculated using the following formula (9): １ =V １Ｎ × {(273.15+T １ ) / 273.15}×{101325 / (101325+P １ ) ... (9)

[0058] The gauge pressure P of the first gas used for the above correction １ and gas temperature T １Regarding the pressure, it is preferable to install a pressure gauge and a thermometer at the nozzle position and measure it directly. If direct measurement is difficult, a pressure gauge and a thermometer may be installed in the piping upstream of the nozzle, or the value of a pressure gauge on the blast furnace wall near the nozzle may be used instead of the nozzle pressure value. Furthermore, the pressure and temperature at the nozzle position may be calculated and used by numerical simulation. Note that when nozzles with different cross-sectional shapes are used in combination, the horizontal gas flow velocity may differ for each nozzle. If the horizontal gas flow velocity differs for each nozzle, the flow rate of each nozzle may be measured and obtained. In this case, the temperature and pressure corrected flow rate of each nozzle is divided by the cross-sectional area of ​​each nozzle to obtain u. ｈ The presence or absence of fluidization can be evaluated individually using equation (1). In addition, when the nozzle is not installed horizontally, the flow velocity of the first gas is taken as a vector in the same direction as the discharge direction from the nozzle, and its horizontal component is taken as u ｈ Let's say.

[0059] [u ｖ ] The vertical upward gas flow velocity in the cylindrical container at the height position of the nozzle is u ｖ (m / s). ｖ The total flow rate V of the first gas and the second gas injected into the container can be calculated as follows: ２Ｎ (Nm ３ / h), and the temperature and pressure corrected flow rate V ２ (m ３ / h) is calculated. ２ Divide by the cross-sectional area of ​​the cylindrical container at the height midway between the nozzle and the top surface of the packed bed, and u ｖ (m / s) is calculated. ２ (m ３ / s) is, specifically, the average gauge pressure P between the height position of the nozzle and the height position of the upper surface of the packed bed ２ (PaG) and average gas temperature T ２ (°C), it can be calculated by the following formula (10). When the nozzles are arranged in multiple stages in the height direction, u ｖ Calculate (m / s). ２ =V２Ｎ × {(273.15+T ２ ) / 273.15}×{101325 / (101325+P ２ ) ... (10)

[0060] The average gauge pressure P ２ and the average gas temperature T ２ Regarding the above, a thermometer and a pressure gauge are installed inside the cylindrical container at a height intermediate between the nozzle and the top surface of the packed bed, and the measured values ​​are used as the average gauge pressure P ２ and the average gas temperature T ２ The thermometer and pressure gauge are preferably installed near the center of the cylindrical container, but if it is difficult to install the instruments, they may be installed near the wall. The pressure and temperature at the corresponding positions in the cylindrical container may also be calculated by numerical simulation and used.

[0061] [ρ ｓｇｉ ] The density of the first gas is ρ ｓｇｉ (kg / m ３ ) ρ ｓｇｉ can be calculated from the composition, temperature, and pressure of the first gas using the gas state equation.

[0062] [μ ｓｇｉ ] The viscosity of the first gas is μ ｓｇｉ (Pa·s). Viscosity values ​​of pure gas species can be obtained from various sources (for example, the Scientific Chronology). μ ｓｇｉ To calculate the viscosity of each pure gas species at the temperature of the first gas, the viscosity of each pure gas species is first obtained, and then the viscosity of each pure gas species is calculated by weighting the viscosity of each pure gas species by the mixture ratio (volume ratio) based on the composition of the first gas.

[0063] [ρ ｂｆ ] The average gas density in the cylindrical container is ρ ｂｆ (kg / m ３ ) ρ ｂｆ can be calculated using the gas state equation from the mixed gas composition of the first gas and the second gas, the temperature, and the pressure at the nozzle height. When only the first gas is blown in, the flow rate of the second gas is assumed to be zero in the calculation.

[0064] [μｂｆ ] The average gas viscosity in the cylindrical container is μ ｂｆ (Pa s). ｂｆ is the viscosity μ of the first gas ｓｇｉ Similarly, the viscosity values ​​of the pure gas species at the second gas temperature are obtained, and the viscosity value is calculated by weighting the viscosity value by the mixture ratio (volume ratio) based on the composition of the second gas.

[0065] If the treatment in the packed bed involves a reaction, the composition and mole number of the gas in the cylindrical vessel change during the treatment. Therefore, it is preferable to calculate the various characteristic values ​​of the gas in the cylindrical vessel described above by taking into account the changes in the gas composition and mole number during the treatment, for example, through reaction calculations, since this allows for more precise calculations. For example, if the cylindrical vessel is a blast furnace, the blast gas (air, oxygen, etc.) blown in through the tuyere, the reducing agent (methane gas, pulverized coal, etc.) blown in through the tuyere, and the coke present in the furnace react near the tuyere to generate bosh gas mainly composed of carbon monoxide and hydrogen. This bosh gas rises within the blast furnace and affects the fluidization behavior near the shaft nozzle. Therefore, if the cylindrical vessel is a blast furnace, it is preferable to use the bosh gas after the reaction near the tuyere as the second gas.

[0066] [f] The average shape factor of all packed particles constituting the packed bed is defined as f(-). f can be determined as follows. A container into which gas can be introduced at a uniform flow rate is prepared, and the packed particles to be measured are packed into the container. The cross-sectional area of ​​the container is made sufficiently larger than the average particle size of the packed particles (for example, about 20 times the average particle size). While the gas is circulated through the container, the pressure is measured at two observation points along the gas flow direction. The shape factor is calculated from the differential pressure ΔP of the obtained measurement results and the distance L between the observation points using the following equation (11) (the so-called Ergin equation). Note that ε and μ in equation (11) ｂｆ , μ ｖ , D ｐ , and ρ ｂｆThe method for determining is as described above, and the values ​​for the packed particles to be measured and the gas used in the measurement are used. When the packed bed is composed of multiple particle types, the shape factor is determined for each particle type as described above, and a weighted average is determined based on the mixing ratio (bulk volume ratio) of each particle type in the packed bed, and the obtained average is designated as f.

[0067] [g] Gravitational acceleration in g (m / s ２ )

[0068] [g'] The inventors conducted extensive experiments by varying the gas conditions and particle conditions, and as a result discovered that even under the same nozzle shape and nozzle gas flow rate, the greater the flow rate of the gas rising inside the cylindrical container, the more likely fluidization occurs near the nozzle. After extensive investigation, the inventors obtained the following findings. That is, the gas rising inside the cylindrical container has the effect of reducing the apparent gravitational acceleration acting on the packed particles, thereby reducing the powder pressure. Therefore, the vertical upward gas flow rate u inside the cylindrical container ｖ By using the apparent gravitational acceleration g' that takes into account the influence of the force of gravity, it is possible to accurately predict whether fluidization will occur even when there is gas rising inside the cylindrical container.

[0069] g' can be calculated from the following equation (5) using the above-mentioned values. Note that, in equation (5), if the gas flow velocity in the vertical upward direction is extremely high, g' may take a negative value. In such a case, the right-hand side of equation (1) is not a real number, and therefore the packed bed treatment cannot be performed under the condition that satisfies equation (1), which falls outside the scope of the present invention.

[0070] Furthermore, when the cylindrical vessel is a blast furnace, a heat flow ratio of 1.1 or less can prevent insufficient temperature rise of the raw material in the blast furnace. Therefore, the heat flow ratio is preferably 1.1 or less, more preferably 1.0 or less, and even more preferably 0.9 or less. On the other hand, a heat flow ratio of 0.4 or more prevents the furnace top temperature from rising excessively, and can suitably prevent breakdowns of the furnace top equipment. Therefore, the heat flow ratio is preferably 0.4 or more, and more preferably 0.6 or more. The heat flow ratio (Ws / Wg) is a value calculated by the following formula (12). Here, C ｐ，ｃ , C ｐ，ｏ , C ｐ，ｇ are the specific heats of coke, ore, and gas, respectively; CR is the coke ratio (kg / molten iron-ton), OR is the ore ratio (kg / molten iron-ton), and BV is the bosh gas consumption rate (Nm ３ / molten iron-ton), BSGI is the basic unit (Nm ３ / molten iron -ton).

[0071] For steps and conditions not described in this specification, conventional methods can be used.

[0072] Example 1: Experimental example using a cold model apparatus A cold model apparatus was used as a cylindrical container. A second gas rising inside the cylindrical container was generated by supplying gas from the bottom of the cylindrical container, and a first gas was supplied from a nozzle on the side of the cylindrical container to investigate the conditions under which fluidization of the packed particles occurs.

[0073] FIG. 1 shows a schematic diagram of the cylindrical vessel 100 used. The cylindrical vessel 100 is a scale model device simulating a blast furnace, and its configuration is as described above. The cylindrical vessel 100 has a shape obtained by cutting out a cylindrical vessel having an inner furnace opening radius of 281 mm and a furnace height of 1570 mm, symmetrically at 20° in the circumferential direction. That is, the A of the cylindrical vessel used ＢＦ is 0.01378m ２ , P ＢＦ The diameter was 0.6601 m. The cylindrical container 100 was a transparent PVC container so that the fluidization behavior of the packed particles could be observed.

[0074] As shown in Figure 1, nozzles 12 were installed on the side (circumferential side) of a cylindrical container 100. The nozzle opening of the nozzle 12 was semicircular, and two nozzles 12 were installed on the left and right at a height of 605 mm from a supply port 16 provided at the bottom of the cylindrical container, at an angle of 0° to the horizontal. A camera (not shown) was installed on the side of the cylindrical container 100 to observe the fluidization of the packed particles in front of the nozzles 12. The nozzles 12 were installed on the semicircular cross section of the nozzle opening (the vertical length D of the nozzle opening) Ｔ The following test was carried out by changing the diameter of the wire (corresponding to the wire diameter) in the range of 7.4 to 14 mm.

[0075] Both the first gas and the second gas were air at room temperature (25° C.) and atmospheric pressure (101,325 Pa). That is, air was supplied to both the nozzle 12 and the supply port 16. Therefore, the density ρ of the first gas was ｓｇｉ and the average gas density ρ in the cylindrical container ｂｆ Similarly, the viscosity μ of the first gas ｓｇｉ and the average gas viscosity μ in the cylindrical container ｂｆ The flow rate of the second gas was changed in the range of 0 to 371 NL / min, and the flow rate of the first gas was changed in the range of 8.7 to 1559.9 NL / min. The height position of the upper surface of the packed bed was changed in the range of 200 to 610 mm above the height position of the nozzle.

[0076] The particles to be packed in the cylindrical container are colored sand (harmonic mean diameter 1.7 mm, bulk density 1501 kg / m ３ ), sinter 1 (harmonic mean diameter 1.7 mm, bulk density 2198 kg / m ３ ), sinter 2 (harmonic mean diameter 3.4 mm, bulk density 2229 kg / m ３ ), poly particles (harmonic mean diameter 3.44 mm, bulk density 628 kg / m ３ ) four types were prepared.

[0077] Simulating the downward loading of raw material particles in a blast furnace, a vibrating feeder at the bottom of the cylindrical vessel was used to extract packed particles at a constant speed, while particles were simultaneously replenished from the top of the cylindrical vessel. By adjusting the amount of packed particles extracted and replenished, the height of the top surface of the packed bed was kept constant.

[0078] Table 1 shows the experimental conditions and results for each example. During the experiment, the fluidization depth was measured using a tape measure installed in the device. In examples in which cavities three times or more the harmonic mean diameter of the packed particles were confirmed, it was determined that the packed particles had fluidized, and "Yes" was recorded in the column for fluidization occurrence in Table 1. On the other hand, in examples in which fluidization of the packed particles was not confirmed, "No" was recorded in the column for fluidization occurrence in Table 1.

[0079] In Figure 3, we observed whether fluidization of the packed particles occurred or not. Ｔ / D Ｐ and P ｉｎｊ / P ｈ The results of plotting the relationship between the particle size and the particle diameter are shown in Figure 3. In Figure 3, "x" is plotted for each case where fluidization occurred, and "o" is plotted for each case where fluidization did not occur. The lines in Figure 3 represent the case where the equal sign in equation (1) is used. ｐ , average bulk density ρ ｐ , average porosity ε, average shape factor f, average internal friction angle φ ｉ , average wall friction coefficient c ｗ Even when the flow rate of the first gas, the flow rate of the second gas, and the height of the upper surface of the packed bed were changed, it was confirmed that fluidization did not occur under the condition satisfying formula (1) of the present invention (the region below and to the left of the line in FIG. 3 ), but fluidization occurred under the condition not satisfying formula (1) (the region above and to the right of the line in FIG. 3 ). Note that No. 68 (Comparative Example) in Table 1 is not plotted in FIG. 3 because the right-hand side of formula (1) is not a real number, but it was confirmed that fluidization occurred in this case as well. Therefore, it was confirmed that the present invention can be applied regardless of the equipment scale, particle properties, gas properties, and operating conditions.

[0080]

[0081] Example 2: Application to a large blast furnace In Example 2, the present invention was evaluated when applied to a large blast furnace. ３It was assumed that the SGI nozzles installed in the blast furnace had a circular cross section, were all positioned at the same height (one stage), and were spaced equally around the periphery of the blast furnace.

[0082] The total flow rate of the SGI gas injected from n SGI nozzles was defined as the first gas flow rate. The flow rate of the bosh gas generated by the reaction of the blast gas (oxygen) injected from the tuyeres installed at the bottom of the blast furnace with the reducing agent (methane, coke) near the tuyeres was defined as the second gas flow rate. The gas density of the upward gas flow ρ ｂｆ , gas viscosity μ ｂｆ was calculated using the gas composition, furnace temperature, and furnace pressure calculated using a blast furnace numerical simulation model described in Non-Patent Document 3. ｂｆ , gas viscosity μ ｂｆ When calculating A, the average value (shaft average) of the region (shaft) between the SGI nozzle height and the upper surface of the raw material filling was used. ｂｆ , P ｂｆ , upward gas flow velocity u ｖ was calculated based on the furnace radius at the midpoint between the SGI nozzle height and the furnace top height. ｓｇｉ , gas viscosity μ ｓｇｉ The calculation was performed using the pressure at the height of the SGI nozzle, the composition of the gas injected from the SGI nozzle, and the gas temperature.

[0083] Three types of filler particles were assumed: lump coke, small lump coke, and raw ore (sintered ore). ｐ , average bulk density ρ ｐ , average porosity ε, average shape factor f, average internal friction angle φ ｉ , average wall friction coefficient c ｗ ) was calculated by averaging the particle properties of each of the raw material particles (lump coke, small coke, and raw ore) weighted by the volume ratio of the raw material input.

[0084] Table 2 shows the calculation results when applied to a blast furnace. From the results obtained, examples that satisfy formula (1) of the present invention are marked with "No", and examples that do not satisfy formula (1) are marked with "Yes" in the fluidization judgment result column of Table 2. Similarly, in Figure 4, when formula (1) of the present invention is satisfied, it is determined that fluidization does not occur and a "○" is plotted, and when formula (1) is not satisfied, it is determined that fluidization occurs and a "×" is plotted. Note that the line in Figure 4 represents the case of the equal sign of formula (1).

[0085]

[0086] According to the present invention, it is possible to provide a method for treating a packed bed that can prevent fluidization of packed particles even when gas is supplied from the side of the container to a packed bed under various conditions.

[0087] 100 Cylindrical vessel 102 Blast furnace 10 Packed bed 12 Nozzle 14 First gas 16 Supply port 18 Second gas 20 Vibration feeder 22 Extraction of packing particles 24 Replenishment of packing particles 30 Raw material particles 32 SGI nozzle 34 Tuyere 36 SGI gas 38 Bosh gas 40 Molten iron

Claims

1. A method for treating a packed bed contained in a cylindrical container, comprising the step of supplying a first gas into the cylindrical container from a nozzle provided on the side of the cylindrical container while the packed bed is contained in the cylindrical container, under conditions that satisfy the following formula (1): D Ｔ / D Ｐ ≦12×(P ｉｎｊ / P ｈ ) －０．２１ ... (1) where, D Ｔ D: Vertical length of the nozzle opening of the nozzle (m) Ｐ P: harmonic mean particle size (m) of all packed particles constituting the packed layer ｉｎｊ : horizontal blast pressure (Pa) of the first gas at the height position of the nozzle ｈ : horizontal powder pressure (Pa) of the packed bed at the height position of the nozzle.

2. The blast pressure P ｉｎｊ and the powder pressure P ｈ The method for treating a packed bed according to claim 1, wherein is calculated based on the following formulas (2) to (5): Here, A ＢＦ : Area (m) of the horizontal cross section of the cylindrical container at a height position intermediate between the nozzle and the upper surface of the packed bed ２ ) P ＢＦ ρ: perimeter (m) of the horizontal cross section of the cylindrical container at a height position midway between the nozzle and the top surface of the packed bed; h: distance (m) from the height position of the nozzle to the height position of the top surface of the packed bed; ｐ : Average bulk density of all the packed particles (kg / m ３ ) ε: average void ratio of the packed bed (-) φ ｉ : average internal friction angle of all the packed particles (°) k: average active powder pressure coefficient of all the packed particles (-) x: penetration distance of the first gas (m) c ｗ : Wall friction coefficient (-) of all the packed particles ｈ : horizontal gas flow velocity of the nozzle (m / s) u ｖ ρ: Vertical upward gas flow velocity (m / s) in the cylindrical container at the height position of the nozzle ｓｇｉ : density of the first gas (kg / m ３ ) μ ｓｇｉ ρ: viscosity of the first gas (Pa s) ｂｆ : average gas density (kg / m) in the cylindrical container ３ ) μ ｂｆ : average gas viscosity in the cylindrical container (Pa s) f: average shape factor of all the packed particles (-) g: gravitational acceleration (m / s ２ g': apparent gravitational acceleration in the cylindrical container (m / s ２ ) 3. A packed bed treatment method according to claim 1 or 2, wherein a second gas rising within the cylindrical container is generated by supplying a gas from a supply port provided at the bottom of the cylindrical container.

4. The packed bed treatment method according to any one of claims 1 to 3, wherein the cylindrical vessel is a blast furnace.

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