Method for treating a packed bed contained in a cylindrical container

Abstract

Provided is a method for treating a packed bed contained in a cylindrical vessel, which can ensure uniformity of gas flow in the circumferential direction within the cylindrical vessel. The method for treating a packed bed contained in a cylindrical vessel includes a step of supplying a gas from a supply port at the bottom of the cylindrical vessel to generate a first gas that rises within the cylindrical vessel, while supplying a second gas from n nozzles on the side of the cylindrical vessel into the cylindrical vessel under conditions where the gas flow uniformity index D represented by formula (1) is 0.60 or more. Here, V1 is the flow rate of the first gas, V2 is the total flow rate of the second gas supplied from the n nozzles, and D C : inner diameter of the cylindrical container at the height position of the nozzle, z: protruding length of the nozzle from the inner surface of the cylindrical container, D N : The horizontal length of the nozzle opening. [0010] TIFF0007582567000011.tif29164

Description

[Technical field]

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

[0002] In recent years, there has been an increasing movement to reduce emissions of CO2 gas (carbon dioxide gas), one of the greenhouse gases, and it is becoming urgent to reduce the use of coal-derived reducing agents in blast furnace operations. Reducing agents have the role of raising the temperature of the charges by generating heat in the furnace, and of reducing the iron-based raw materials (iron ore, sintered iron ore, iron ore pellets, etc.) in the furnace. Hydrogen has attracted attention as a reducing agent aimed at reducing CO2 gas emissions. The reduction rate with hydrogen is faster than that with CO gas, so by injecting hydrogen-based gas into the blast furnace, it is possible to simultaneously reduce CO2 gas emissions and increase the reduction efficiency.

[0003] Since the reduction of iron-based raw materials by hydrogen is an endothermic reaction, there was a problem that the temperature rise of the charge in the blast furnace was delayed and smooth reduction could not be achieved. Therefore, an operation method for avoiding the influence of poor temperature rise of the charge in the upper part of the furnace has been disclosed. Patent Document 1 discloses a method for making a part or all of the preheat gas injection nozzle movable forward and backward toward the furnace when injecting gas from the shaft in an oxygen blast furnace, thereby allowing the preheat gas to reach the core. Patent Document 2 discloses a method for preventing poor temperature rise of the charge in the upper part of the furnace during low reducing agent ratio operation in a conventional blast furnace by setting the shaft gas injection angle to 45° or less, and effectively suppressing moisture condensation and wall adhesion of zinc compounds due to a drop in the furnace top temperature, thereby stably performing low reducing agent ratio operation. Patent Document 3 discloses a method for avoiding poor temperature rise at the furnace top at low cost without requiring large-scale capital investment by controlling any one or a combination of two or three of the blowing temperature, blowing amount, and blowing height position of shaft gas from the shaft part according to the furnace top gas temperature during blast furnace operation using ferro-coke as part of the charged raw materials. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 6-19088 [Patent Document 2] JP 2011-214022 A [Patent Document 3] JP 2011-32584 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional blast furnace operation method, the gas flow rate, nozzle projection length, nozzle diameter, number of nozzles, etc., which can ensure uniformity of gas flow in the circumferential direction in the blast furnace, were not fully considered, and there was room for improvement. With the conventional blast furnace operation method, the temperature in the circumferential direction in the blast furnace becomes non-uniform, which causes the reduction rate distribution in the circumferential direction to become non-uniform, and the average reduction efficiency in the blast furnace deteriorates, making it impossible to perform optimal low reducing agent ratio operation. In addition, there is a concern that the non-uniform temperature distribution in the circumferential direction in the blast furnace will cause bias in gas permeability, increase the ventilation resistance in the furnace, and induce blow-by. Similar issues are not limited to blast furnaces, but apply generally to the treatment of packed beds contained in cylindrical containers.

[0006] In view of the above circumstances, an object of the present invention is to provide a method for treating a packed bed contained in a cylindrical vessel, which is capable of ensuring uniformity of gas flow in the circumferential direction within the cylindrical vessel. [Means for solving the problem]

[0007] The present inventors have conducted intensive research to solve the above problems, and have obtained the following findings. When treating a packed bed contained in a cylindrical vessel, the gas flow uniformity index represented by the flow rate of gas rising in the cylindrical vessel, the total flow rate of gas supplied from n nozzles provided at intervals in the circumferential direction on the side of the cylindrical vessel, the inner diameter of the cylindrical vessel at the height position of the nozzles, the projection length of the nozzles from the inner circumferential surface of the cylindrical vessel, the nozzle aperture, and the number n of nozzles is within a predetermined range, thereby ensuring the uniformity of the gas flow in the circumferential direction in the cylindrical vessel and realizing a balanced gas flow in the vessel. By applying this finding to a blast furnace as a cylindrical vessel, it is possible to prevent poor charge temperature rise, deterioration in reduction efficiency, and deterioration in permeability, and also effectively suppress moisture condensation due to a decrease in furnace top temperature, thereby realizing stable blast furnace operation.

[0008] That is, the gist and configuration of the present invention are as follows.

[0009] [1] A method for treating a packed bed contained in a cylindrical container, comprising the steps of: a step of supplying a second gas into the cylindrical container from n nozzles provided at intervals in the circumferential direction on a side portion of the cylindrical container while generating a first gas that rises inside the cylindrical container by supplying a gas from a supply port provided at a lower portion of the cylindrical container with the packed bed contained in the cylindrical container, under a condition that a gas flow uniformity index D represented by the following formula (1) is 0.60 or more.

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[0010] [2] The method for treating a packed bed contained in a cylindrical vessel according to [1] above, wherein the gas flow uniformity index D is 1.00 or more.

[0011] [3] The flow rate V of the first gas, the total flow rate V of the second gas supplied from the n nozzles, the protruding length z of the n nozzles from the inner circumferential surface of the cylindrical container, and the horizontal length D of the nozzle openings of the n nozzles. N and when selecting the number n of the nozzles, confirming that the gas flow uniformity index D is 0.60 or more.

[0012] [4] The flow rate V1 of the first gas, the total flow rate V2 of the second gas supplied from the n nozzles, the protruding length z of the n nozzles from the inner circumferential surface of the cylindrical container, and the horizontal length D of the nozzle openings of the n nozzles are set so that the gas flow uniformity index D is 0.60 or more. N and at least one of the number n of the nozzles is adjusted.

[0013] [5] The protruding length z of the n nozzles from the inner circumferential surface of the cylindrical container and the inner diameter D of the cylindrical container at the height position of the n nozzles C Ratio of z / D C The method for treating a packed bed contained in a cylindrical container according to any one of the above [1] to [4], wherein the value of the packed bed is 0.25 or less.

[0014] [6] The method for treating a packed bed contained in a cylindrical vessel according to any one of the above [1] to [5], wherein the cylindrical vessel is a blast furnace. Effect of the Invention

[0015] According to the packed bed treatment method of the present invention, uniformity of the gas flow in the circumferential direction within the cylindrical vessel can be ensured. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a schematic diagram showing (a) the external structure and (b) the internal structure of a cylindrical container used in an example of the present invention. [Diagram 2] 1 is a horizontal cross-sectional view of a cylindrical container used in one embodiment of the present invention, taken at a height position where a nozzle is provided. [Diagram 3] 1A and 1B are horizontal cross-sectional views of a cylindrical container used in one embodiment of the present invention at a height position where a nozzle is installed, in cases where (a) the nozzle diameter is small and (b) the nozzle diameter is large. [Figure 4] FIG. 2 is a schematic vertical cross-sectional view showing an enlarged view of a portion of a cylindrical container used in an example of the present invention where a nozzle is provided. [Diagram 5] FIG. 13 is a diagram showing a result of measuring temperature distribution in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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] The cylindrical container used in one embodiment of the present invention accommodates a packed bed inside, has a supply port at the bottom, and has a plurality of nozzles (the number of nozzles n is an integer of 2 or more) at intervals in the circumferential direction at the side. FIG. 1 shows schematic diagrams of (a) the external structure and (b) the internal structure of a cylindrical container 100 used in an embodiment of the present invention. With a packed bed 30 accommodated inside the cylindrical container 100, a gas is supplied into the cylindrical container 100 from a supply port 40 provided at the bottom of the cylindrical container 100, generating a first gas 42 that rises inside the cylindrical container, while a second gas 24 is supplied into the cylindrical container 100 from n nozzles 20 provided at intervals in the circumferential direction at the side of the cylindrical container 100. The second gas 24 is supplied from each nozzle 20 toward the center inside the cylindrical container 100, and the second gas 24 diffuses around the nozzle port.

[0019] The position of the maximum height of the packed bed 30 contained inside the cylindrical container 100 is set as a reference height, and the nozzle 20 is installed at a position lower than the reference height. The height is preferably such that the value obtained by dividing the distance from the reference height to the installation height of the nozzle 20 by the distance from the reference height to the position of the supply port 40 is 0.1 to 0.9. By setting this value to 0.1 or more, it is possible to suitably prevent particles on the surface of the packed bed 30 from being fluidized and blowing through. By setting this value to 0.9 or less, it is possible to suitably prevent the second gas 24 from being introduced before the first gas 42 spreads to the furnace wall of the cylindrical container 100. It is preferable that the cylindrical container 100 is installed so that the axis in the height direction of the cylindrical container 100 is parallel to the vertical direction.

[0020] FIG. 2 shows a horizontal cross-sectional view of the cylindrical container 100 used in one embodiment of the present invention at a height position where the nozzles 20 are provided. FIG. 2 shows a case where six nozzles 20 are provided on the side portion 10 of the cylindrical container 100. The second gas diffusion range 22 is represented as a semicircle or semiellipse centered on the tip of the nozzle 20 in the horizontal cross-section of the cylindrical container 100. In FIG. 2, all of the nozzles 20 are provided at the same height position of the cylindrical container 100, are provided in the circumferential direction of the side portion 10 of the cylindrical container 100, and are provided so that the nozzle mouth faces the center inside the cylindrical container 100. In FIG. 2, the angle of the nozzles 20 is perpendicular to the height direction of the cylindrical container 100.

[0021] 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. Note that the present invention can be applied to any other vessel than a blast furnace, such as a shaft furnace having a structure in which gas is blown in from the side and bottom of the cylindrical vessel.

[0022] The packed bed accommodated inside the cylindrical vessel can be appropriately selected by the practitioner according to the type and use of the cylindrical vessel. As shown in formula (1), the gas flow uniformity index D is not affected by the properties of the particles (particle size, particle density, particle shape factor, etc.). Therefore, the present invention can be applied regardless of the type of particles constituting the packed bed. 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, and for example, for a blast furnace with a height of 10 m and an inner furnace diameter of 3 m, the particle size can be 10 to 50 mm. When the cylindrical vessel is a blast furnace, the raw material density of the packed bed can be 900 to 1810 kg / m 3 It is preferable that:

[0023] Generally, a physical phenomenon is expressed as a specific physical quantity (gas flow rate V1 (Nm 3 / t), the horizontal length of the nozzle opening D Netc.), but rather, appropriately non-dimensionalized parameters (V2 / (V1+V2), D N / D C It is known that by using the law of similarity, it is possible to describe a generalized phenomenon that can be applied to a wide range of targets, regardless of the size, physical properties, or operating conditions (flow rate, temperature, pressure, etc.) of the equipment. This is called the law of similarity, and is an evaluation method that is 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 have examined whether it is possible to describe a gas flow uniformity index using dimensionless parameters that is independent of the equipment scale, gas properties, or operating conditions. As a result, it was found that the flow rate ratio (V2 / (V1+V2)) of the first gas rising inside the cylindrical vessel to the second gas supplied from the nozzle, and the ratio of the lengths of the model equipment (D N / D C and z / D C It was found that by describing the gas flow uniformity index D using three non-dimensional parameters, namely, θ and θ, the gas flow uniformity can be evaluated regardless of the equipment scale, gas properties, or operating conditions.

[0024] From the above, the gas flow uniformity index D used in the present invention is an index that can be applied to equipment with different equipment scales, gas properties, and operating conditions, and can be widely applied not only to cylindrical model vessels but also to blast furnaces and the like.

[0025] In the present invention, the gas flow uniformity index D is a calculated value of the ratio of the area where the gas supplied from the nozzle diffuses on the circumference of a circle connecting the nozzle tips in the cylindrical container. The gas flow uniformity index D is expressed by the formula (1).

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[0026] When the cylindrical vessel is a blast furnace, the tuyere at the bottom of the blast furnace is regarded as the supply port at the bottom of the cylindrical vessel, and the SGI nozzle at the shaft of the blast furnace is regarded as the nozzle at the side of the cylindrical vessel. In other words, the flow rate V1 of the first gas is the bosh gas flow rate V BOSH [Nm 3 / molten iron-ton], the total flow rate of the second gas V2 is the total flow rate of the shaft gas V SGI [Nm 3 / molten iron-ton], horizontal length of nozzle opening D N is the inner diameter of the SGI nozzle D SGI As for the flow rate [m], the above formula (1) is expressed by the following formula (2): Here, the bosh gas flow rate refers to the total flow rate of reducing gas (CO, H2, N2, etc.) generated by the reaction of the gas injected from the tuyere with the coke at the tip of the tuyere in the raceway.

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[0027] Equation (1) or (2) assumes that the gas supplied from the nozzle spreads in a semi-elliptical shape, and is expressed as the horizontal length D of the nozzle opening. N This is an equation that takes into account the above. That is, the gas flow uniformity index D evaluates the gas diffusion range taking into account the nozzle diameter. FIG. 3 shows horizontal cross-sectional views of the nozzle installation positions of a cylindrical container used in one embodiment of the present invention, in the cases of (a) a small nozzle diameter and (b) a large nozzle diameter. In the case of FIG. 3(a), the second gas diffusion range 22 diffuses in a semicircular shape, and in the case of FIG. 3(b), the second gas diffusion range 22 diffuses in a semi-elliptical shape. In either case, the gas flow uniformity can be evaluated with high accuracy by using the gas flow uniformity index D.

[0028] In formula (1) or formula (2), when the gas flow uniformity index D is 0.60 or more, the circumferential gas flow uniformity in the cylindrical container can be ensured. When the gas flow uniformity index D is 1.00 or more, the gas flow uniformity can be more sufficiently ensured. Therefore, in formula (1) or formula (2), the gas flow uniformity index D is 0.60 or more, preferably 1.00 or more, and more preferably 1.10 or more. Moreover, the gas flow uniformity index D is approximately 10.00 or less.

[0029] The flow rate V1 of the first gas rising inside the cylindrical vessel, the total flow rate V2 of the second gas supplied from n nozzles arranged at intervals in the circumferential direction on the side of the cylindrical vessel, the protruding length z of the n nozzles from the inner circumferential surface of the cylindrical vessel, and the horizontal length D of the nozzle openings of the n nozzles. N When selecting the number of nozzles n, it is preferable to confirm that the gas flow uniformity index D is 0.60 or more. By making the above selection and designing the cylindrical container, the gas flow uniformity can be suitably ensured.

[0030] The flow rate V1 of the first gas, the total flow rate V2 of the second gas supplied from the n nozzles, the protruding length z of the n nozzles from the inner circumferential surface of the cylindrical container, and the horizontal length D of the nozzle openings of the n nozzles are set so that the gas flow uniformity index D is 0.60 or more. N and the number n of nozzles. By making the above adjustments, the uniformity of the gas flow can be suitably ensured.

[0031] The flow rate V1 of the first gas rising in the cylindrical container and the flow rate V2 of the second gas supplied from n nozzles spaced apart in the circumferential direction on the side of the cylindrical container are appropriately adjusted according to the size of the cylindrical container. Here, the ratio V2 / (V1+V2) of V2 to the total flow rate of V1 and V2 is preferably 0.1 or more from the viewpoint of favorably forming the shape of the second gas diffusion range 22 (semicircle or semiellipse centered on the tip of the nozzle 20). Furthermore, since the shape of the second gas diffusion range 22 is favorably formed even if the flow rate of the first gas is 0, it is preferable that V2 / (V1+V2) is 1.0 or less.

[0032] The flow rate V1 of the first gas can be calculated from the composition and flow rate of the gas etc. supplied from the supply port at the bottom of the cylindrical vessel, and the composition change due to the chemical reaction in the furnace. For example, in the case of a cylindrical vessel where no chemical reaction occurs, the amount of gas flowing in from the supply port at the bottom of the cylindrical vessel can be taken as the flow rate V1 of the first gas. In addition, in the case of a cylindrical vessel that is a blast furnace, the bosh gas generated when the gas etc. supplied to the tuyere reacts with the coke at the end of the tuyere in the raceway can be taken as the first gas. The bosh gas flow rate can be calculated if the composition and flow rate of the gas etc. (blast gas and reducing material blown into the tuyere, etc.) blown in from the tuyere are known.

[0033] The first gas and the second gas may be air or the like. From the viewpoint of heating and raising the temperature of the packed bed, the temperature of at least one of the first gas and the second gas is preferably higher than the atmospheric temperature around the cylindrical container, for example, 40° C. or higher. From the viewpoint of protecting the device, the temperatures of the first gas and the second gas are preferably lower than the heat-resistant temperature of the device, for example, 60° C. or lower when the cylindrical container is made of PVC.

[0034] In order to simplify the evaluation, the flow rate V1 of the first gas and the flow rate V2 of the second gas can be the gas flow rate under standard conditions (0°C, 1 atm). This is because if the first gas and the second gas are at the same temperature, the value of V1 / (V1+V2) in formula (1) is the same regardless of the temperature. Even if the temperatures of the first gas and the second gas are different, if the temperature difference between the first gas and the second gas is within 20% in absolute temperature (K), the effect on the present invention is small, so the gas flow rate under standard conditions can be used. Similarly, if the number of moles of the first gas or the second gas increases or decreases due to a reaction in the cylindrical vessel, the gas volume changes, but if the change in the number of moles due to the reaction is 20% or less, the effect on the present invention is small, so the present invention can be applied using the gas flow rate before the reaction. In addition, if the cylindrical vessel is a blast furnace, a gasification reaction accompanied by a large volume change occurs in the region (raceway) immediately after the blast gas is blown into the furnace from the tuyere. However, in the reduction reaction, which is the main reaction in the blast furnace, the number of moles does not change, so the volume change is small and the present invention can be applied. Therefore, when the cylindrical vessel is a blast furnace, the flow rate of the bosh gas in the raceway is set as the first gas flow rate V1 and the present invention is applied.

[0035] Bosh gas is a reducing gas (CO, H2, N2, etc.) generated when gas supplied to the tuyere of the blast furnace reacts with the coke at the end of the tuyere in the raceway. From the viewpoint of promoting the reduction reaction of the ore, the temperature of the bosh gas at the nozzle height is preferably 560°C or higher. Also, from the viewpoint of preventing 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.

[0036] The gas supplied to the tuyere of the blast furnace is preferably air or oxygen, and a gaseous reducing agent such as methane, from the viewpoint of reducing CO2 gas emissions. The temperature of the gas supplied to the tuyere is preferably 0°C or higher from the viewpoint of ensuring the gas temperature at the tuyere tip. Moreover, the temperature of the gas supplied to the tuyere is preferably 1300°C or lower from the viewpoint of preventing an excessive temperature rise of the gas at the tuyere tip.

[0037] The gas supplied to the SGI nozzle of the blast furnace is preferably a reducing gas containing CO, H2, etc., from the viewpoint of not inhibiting the reduction of the iron-based raw materials in the blast furnace. If the gas contains a reducing gas, it may also contain an oxidizing gas such as CO2 or H2O or an inert gas such as N2. In addition, since it is necessary to supply gas from the SGI nozzle at a temperature higher than the gas temperature when the bosh gas rises to the nozzle position, the temperature of the gas supplied to the SGI nozzle is preferably 400 ° C or higher. In addition, the temperature of the gas supplied to the SGI nozzle is preferably 1000 ° C or lower from the viewpoint of preventing energy loss due to overheating of the gas temperature. Specifically, it is preferable to use a preheated gas generated by partially burning the blast furnace gas discharged from the blast furnace, for example.

[0038] If the number n of nozzles provided at intervals in the circumferential direction on the side of the cylindrical container is 2 or more, the effect of the present invention can be obtained, and if it is 3 or more, the gas flow uniformity can be more suitably obtained. Therefore, the number n of nozzles is 2 or more, and preferably 3 or more. On the other hand, if the number n of nozzles is 50 or less, the equipment cost and maintenance cost can be suitably suppressed and the operation can be efficiently performed. Therefore, the number n of nozzles is preferably 50 or less. The nozzles are preferably provided at equal intervals in the circumferential direction on the side of the cylindrical container. Note that, although it is easier to make the gas flow in the cylindrical container uniform as the number of nozzles increases, there are cases where the uniformity cannot be ensured even when the number of nozzles is large, depending on the gas flow rate, etc. In the present invention, even when the number of nozzles is small, the gas flow uniformity in the cylindrical container can be ensured by satisfying that the gas flow uniformity index D is within a predetermined range.

[0039] Horizontal length of nozzle opening D N When D is equal to or larger than the harmonic mean diameter of all the packed particles constituting the packed bed, the shape of the second gas diffusion area 22 is suitably formed. N is preferably equal to or larger than the harmonic mean diameter of all the packed particles constituting the packed bed. For example, when the harmonic mean diameter of the raw material particles is 0.02 [m], D NIt is preferable that D is 0.02 [m] or more. N When D is 10 times or less of the harmonic mean diameter of all packed particles, the raw material particles in the packed bed can be effectively prevented from flowing back to the nozzle. N is preferably 10 times or less, more preferably 5 times or less, of the harmonic mean diameter of all the packed particles constituting the packed bed. For example, when the harmonic mean diameter of the raw material particles is 0.02 [m], D N is preferably 0.20 [m] or less, and more preferably 0.10 [m] or less.

[0040] 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 horizontal direction is D N The nozzle is not limited to a single-hole nozzle, and a multi-hole nozzle may be used. A multi-hole nozzle may have a plurality of discharge holes arranged at equal intervals and close to each other. For example, a nozzle having multiple holes formed by bundling multiple pipes, a nozzle tip having multiple holes attached to the end of a single pipe, or a single-hole nozzle having multiple holes formed by attaching a net to the nozzle, etc. may be used. When a multi-hole nozzle is used, the horizontal length D of the nozzle opening may be N is the horizontal length from the rightmost end of the rightmost nozzle to the leftmost end of the leftmost nozzle among the multiple nozzles in the multi-hole nozzle. When a multi-hole nozzle is used, it is possible to prevent the raw material particles from entering the nozzle. When the horizontal length of the nozzle orifice differs for each nozzle, the horizontal length D of the nozzle orifice is calculated by arithmetically averaging the horizontal lengths of the nozzle orifices for n nozzles. N This can be done as follows.

[0041] In addition, the nozzle does not necessarily have to be disposed horizontally, and may be disposed at an angle to the side of the cylindrical container. When the nozzle is disposed at an angle to the side of the cylindrical container, the nozzle height position is defined as the height of the nozzle tip.

[0042] Furthermore, it is not necessary for all the nozzles to be arranged at the same height, 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 position of the highest nozzle is taken as the nozzle height position. Inner diameter D of the cylindrical container C The gas flow uniformity index D is calculated using the inner diameter of the cylindrical vessel at the height of the highest nozzle and the total number of nozzles arranged in multiple stages as the number of nozzles n.

[0043] The length z of the nozzles protruding from the inner surface of the cylindrical container, which are spaced apart from each other in the circumferential direction on the side of the cylindrical container, and the inner diameter D of the cylindrical container at the height where the nozzles are installed are C Ratio of z / D C When z / D is 0.25 or less, the load drop can be suppressed favorably. C is preferably 0.25 or less, and more preferably 0.20 or less. C The lower limit of z / D is not particularly limited and may be 0.00. C By protruding the nozzle from the inner peripheral surface of the cylindrical container so that z / D is 0.02 or more, it is easy to keep the gas flow uniformity index D within a predetermined range. C is preferably 0.02 or more. When the nozzles are protruding from the inner peripheral surface of the cylindrical container, it is preferable that the protruding lengths of the n nozzles are all the same. When the protruding lengths are different, D is calculated using the value of z for the nozzle with the shortest protruding length.

[0044] Furthermore, when the cylindrical vessel is a blast furnace, if the heat flow ratio is 1.0 or less, the reducing agent ratio in blast furnace operation can be reduced. Therefore, the heat flow ratio is preferably 1.0 or less, and more preferably 0.9 or less. On the other hand, if the heat flow ratio is 0.4 or more, the heat exchange between the gas and solid in the blast furnace proceeds efficiently, which is suitable for raising the temperature of the raw materials. 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 (3).

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[0045] For steps and conditions not described in this specification, conventional methods can be used. EXAMPLES

[0046] <Example 1: Cylindrical container test> A heat treatment test was carried out using a cylindrical vessel simulating a blast furnace. FIG. 1 shows a schematic diagram of the external structure (a) and the internal structure (b) of the cylindrical vessel used. The cylindrical vessel 100 is an opaque PVC vessel with a size equivalent to about 1 / 10 of a blast furnace in actual operation, an inner dimension of a furnace mouth radius of 300 mm, and a furnace height of 1000 mm. The cylindrical vessel 100 has a supply port 40 at the center of the bottom surface of the vessel, a gas injection nozzle 20 on the side, and a packed bed 30 inside the vessel. In FIG. 1(a), some of the gas injection nozzles 20 are not shown, but six or thirty nozzles 20 were installed at equal intervals in the circumferential direction of the cylindrical vessel 100. As the packed bed 30 inside the cylindrical container 100, the horizontal position of the bottom of the cylindrical container 100 was set to 0 mm, and from 0 mm to 200 mm, BB bullets with a large particle size of about φ6 mm were packed to generate a gas flow that uniformly rises in the cross section of the cylindrical container. Furthermore, at a position 200 mm from the horizontal position of the bottom of the cylindrical container 100, the BB bullet packed bed 36 was fixed using a wire mesh 34. In addition, at a position 200 mm to 800 mm of the cylindrical container 100, PE particles with a size of about φ3 mm simulating the raw materials in a blast furnace were packed to form a PE particle packed bed 32. The gas injection nozzle 20 was installed at a height of 400 mm, with the horizontal position of the bottom of the cylindrical container 100 being set to 0 mm. In addition, air heated to about 60° C. was blown from the supply port 40 to generate a first gas 42 that rises in the cylindrical container. While air at 20° C. was blown as the second gas 24 from the gas blowing nozzle 20, the temperature distribution inside the cylindrical container 100 was observed from above the container at a height of 400 mm above the installation height of the gas blowing nozzle 20 with a thermographic camera 50.

[0047] 4 shows a schematic vertical cross-sectional view of the cylindrical vessel used, enlarging the area where the nozzle was installed. The nozzle 20 was installed on the side 10 of the cylindrical vessel perpendicular to the height direction of the cylindrical vessel, and injected the second gas 24 into the packed bed 32 of PE particles contained inside the cylindrical vessel.

[0048] Table 1 shows the experimental conditions for the cylindrical vessel. The number of nozzles in the cylindrical vessel was set to 6 or 30. The blowing conditions for the cylindrical vessel were set to a constant flow rate ratio with the blast furnace, taking into account the gas flow in the packed bed. The nozzle used in Example 1 was a pipe simulating an SGI nozzle, with an outer diameter of 15 mm and an inner diameter of 5 or 9 mm (the horizontal length of the nozzle opening D N When converted to the scale ratio of an actual blast furnace, the above nozzle inner diameter of 5 mm corresponds to an SGI nozzle diameter of 0.050 m, and the above nozzle inner diameter of 9 mm corresponds to an SGI nozzle diameter of 0.090 m.

[0049] [Table 1]

[0050] Table 2 shows the experimental conditions, experimental results, and the calculation results of the gas flow uniformity index D when a pipe with an outer diameter of 15 mm and an inner diameter of 5 mm was used. Figure 5 also shows the temperature distribution measurement results. Figures 5(a) to (d) show the measurement results in Table 2, specifically, (a): No. 1, (b): No. 3, (c): No. 2, and (d): No. 4. The white dotted lines in Figures 5(a) to (d) indicate isothermal lines, and the numbers corresponding to each white dotted line indicate the temperature of the corresponding white dotted line. As shown in Figures 5(c) and (d), when the temperature difference is within 20°C on the outer circumference of the circle in the observed range (when one or less of the white dotted lines intersects with the circle), the gas flow in the circumferential direction of the cylindrical container is determined to be uniform, and is marked with "◎" in Table 2. As shown in Figure 5(b), when the temperature difference on the periphery of the circle in the observed range is more than 20°C and less than 30°C (when two of the white dotted lines intersect with the circle), the gas flow in the circumferential direction of the cylindrical vessel is judged to be approximately uniform, and this is recorded as "○" in Table 2. As shown in Figure 5(a), when the temperature difference on the furnace wall side is more than 30°C (when three or more of the white dotted lines intersect with the circle), the gas flow in the circumferential direction of the cylindrical vessel is judged to be not uniform, and this is recorded as "×" in Table 2. In subsequent tests, the uniformity of the gas flow was evaluated using the same criteria.

[0051] From No.1 and No.2, it was found that the circumferential gas flow uniformity of the cylindrical vessel was improved by increasing the number of gas injection nozzles from 6 to 30 under the condition that the amount of injected second gas was constant. Also, from No.3 and No.4, it was confirmed that the same tendency as No.1 and No.2 was observed when the amount of injected second gas was increased. However, in No.3, which had a large injected gas amount, the circumferential gas flow of the cylindrical vessel was roughly uniform even though the number of gas injection nozzles was small. Furthermore, from No.5, it was found that the circumferential gas flow uniformity of the cylindrical vessel was improved even when the nozzles were protruded into the furnace while keeping the number of gas injection nozzles and gas injection amount fixed.

[0052] [Table 2]

[0053] Table 3 shows the outer diameter of the nozzle, 15 mm, the inner diameter of the nozzle, 9 mm (horizontal length of the nozzle opening D N The experimental conditions and results are shown in Tables 2 and 3, where a pipe of 0.009 [m] was used. As shown in Tables 2 and 3, the evaluation results of the circumferential gas flow uniformity based on the direct observation of temperature are consistent with the evaluation results based on the gas flow uniformity index D of the present invention (D of 0.60 or more is preferable, and 1.00 or more is even more preferable), and it was confirmed that the gas flow uniformity can be evaluated by the present invention.

[0054] [Table 3]

[0055] <Example 2: Blast furnace condition calculation results> As described above, the gas flow uniformity index D is an index composed of dimensionless parameters that are not dependent on the size of the equipment or the physical properties of the gas, so the present invention is a method that can be applied to a wide range of objects, not limited to cylindrical vessels. In Example 2, the gas flow uniformity index D was used to evaluate the uniformity of the gas flow in a large blast furnace.

[0056] The gas flow uniformity was calculated assuming the conditions when a large blast furnace is operated using methane gas. Table 1 shows the operating conditions of a blast furnace reproduced by a cylindrical vessel. In this calculation, the inner diameter D C In a blast furnace with a diameter of 4.6 m, it was assumed that 200 kg / t of methane gas was supplied from the tuyeres. C In a blast furnace with a diameter (m) of 12.4 m, it was assumed that 160 kg / t of methane gas was supplied from the tuyere. Thirty shaft gas injection nozzles were installed around the circumference of the blast furnace, and when the number of nozzles was reduced, the nozzles were thinned out to be equally spaced, and calculations were performed for the cases of 30, 15, and 6 nozzles. It was assumed that the gas injected into the blast furnace from the tuyere at the bottom of the blast furnace was oxygen gas and methane gas, which reacted in the raceway immediately after the tuyere to become bosch gas and rise inside the blast furnace. Two types of calculations were performed with nozzle diameters of 0.05 m and 0.09 m.

[0057] The operating conditions and calculation results are shown in Tables 4 and 5. Based on the results of Example 1, the uniformity of the gas flow in the circumferential direction of the blast furnace was judged as "◎" if the gas flow uniformity index D was 1.00 or more, "○" if it was less than 1.00 and 0.60 or more, and "×" if it was less than 0.60.

[0058] [Table 4]

[0059] [Table 5] [Industrial Applicability]

[0060] According to the present invention, it is possible to provide a method for treating a packed bed contained in a cylindrical vessel, which is capable of ensuring uniformity of gas flow in the circumferential direction of the cylindrical vessel. [Explanation of symbols]

[0061] 100 Cylindrical container 10 Side of cylindrical container 20 Nozzles 22 Second gas diffusion range 24 Second Gas 30 Filled bed 32 PE particle packed bed 34 Wire Mesh 36 BB bullet packing layer 40 Supply port 42 First Gas 50 Thermography Camera

Claims

1. A method for treating a packed bed contained in a cylindrical container, comprising the steps of: a step of supplying a second gas into the cylindrical container from n nozzles provided at intervals in the circumferential direction on a side portion of the cylindrical container while generating a first gas that rises inside the cylindrical container by supplying a gas from a supply port provided at a lower portion of the cylindrical container with the packed bed contained in the cylindrical container, under a condition in which a gas flow uniformity index D represented by the following formula (1) is 0.60 or more. [0010] Where: V １ : Flow rate of the first gas [NL / min] V ２ : total flow rate of the second gas supplied from the n nozzles [NL / min] D Ｃ : inner diameter of the cylindrical container at the height position of the n nozzles [m] z: protruding length of the n nozzles from the inner circumferential surface of the cylindrical container [m] D Ｎ : Horizontal length of the nozzle opening of the n nozzles [m] It is.

2. 2. The method for treating a packed bed contained in a cylindrical vessel according to claim 1, wherein the gas flow uniformity index D is 1.00 or more.

3. The flow rate V of the first gas １ , the total flow rate V of the second gas supplied from the n nozzles ２ , the protruding length z of the n nozzles from the inner peripheral surface of the cylindrical container, the horizontal length D of the nozzle openings of the n nozzles Ｎ 2. The method for treating a packed bed contained in a cylindrical container according to claim 1, further comprising the step of confirming that the gas flow uniformity index D is 0.60 or more when selecting the number n of nozzles and the number of nozzles n.

4. The flow rate V of the first gas is adjusted so that the gas flow uniformity index D is 0.60 or more. １ , the total flow rate V of the second gas supplied from the n nozzles ２ , the protruding length z of the n nozzles from the inner peripheral surface of the cylindrical container, the horizontal length D of the nozzle openings of the n nozzles Ｎ 2. The method for treating a packed bed contained in a cylindrical container according to claim 1, further comprising adjusting at least one of the number of nozzles, n, and the number of nozzles.

5. The protruding length z of the n nozzles from the inner peripheral surface of the cylindrical container and the inner diameter D of the cylindrical container at the height position of the n nozzles Ｃ The ratio z / D Ｃ 2. The method for treating a packed bed contained in a cylindrical container according to claim 1, wherein the σ is 0.25 or less.

6. The method for treating a packed bed contained in a cylindrical vessel according to any one of claims 1 to 5, wherein the cylindrical vessel is a blast furnace.

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