Granular iron production device

Abstract

Provided is a nodular iron manufacturing apparatus that can efficiently cool molten iron and, in a conveying apparatus such as a conveyor, also efficiently cool nodular iron during conveyance to suppress coalescence of nodular iron pieces with each other. A nodular iron manufacturing apparatus having a granulating device that makes molten iron into droplets, a cooling water tank that cools the droplets by dropping them into cooling water to form nodular iron, and a conveying device that conveys the nodular iron out of the cooling water tank, the apparatus comprising: a water flow control container provided in the cooling water tank and having openings at upper and lower ends; and a group of cooling water pipes that supply cooling water into the water flow control container, the conveying device comprising: a conveyor provided below the water flow control container for conveying nodular iron from inside the cooling water tank to outside the cooling water tank; and a cooling water supply device provided above the conveyor in the cooling water tank for supplying cooling water for cooling nodular iron carried out by the conveyor.

Description

Technical Field

[0001] The present invention relates to a granular iron production apparatus for producing granular iron from molten iron.

Background Art

[0002] Granular iron is obtained by dispersing molten iron such as molten iron or molten steel and then solidifying it into granules, and its average particle size is about several millimeters to several tens of millimeters. In an integrated steelworks, when troubles occur in the processes below steelmaking and the molten iron produced in the blast furnace suddenly becomes excessive, it is temporarily stored as granular iron. In recent years, blast furnaces have been enlarged, and if a large amount of molten iron cannot be processed temporarily, it will lead to a reduction in the blast volume of the blast furnace. Therefore, in case troubles occur in the processes below steelmaking, a buffering facility is required.

[0003] Due to the recent demand for reducing CO2 emissions in the iron and steel industry, the need for reduced iron produced using hydrocarbon gas-based gases such as hydrogen or natural gas as reducing agents instead of coke (carbon source) is increasing. In order to produce steel products from reduced iron with high gangue (mainly SiO2 and Al2O3) and P concentrations, it is essential to remove gangue and dephosphorize after the production of reduced iron. Therefore, as a pretreatment for producing steel products, reduced iron may be once melted into molten iron, then processed such as gangue removal and dephosphorization, and the processed molten iron may be stored as transportable granular iron.

[0004] As a method for granulating molten iron, Patent Document 1 discloses a method of granulating by spraying pressurized water onto molten iron. However, in the method disclosed in Patent Document 1, many of the granular iron becomes hollow, and water accumulates in this hollow part, posing a risk of causing a steam explosion during re-dissolution. Patent Document 2 discloses a method for producing granular metal in which molten iron is dropped onto a fixed plate, the droplets bounce back on the fixed plate and fall into the lower cooling bath below for cooling, thereby producing granular iron. The granular iron cooled in the cooling water tank is collected by a cylindrical flat plate structure and a pipe whose lower half of the cylinder tapers and is connected, stacked on a conveyor which is a conveying device, and the granular iron is conveyed from the cooling water tank to a drying device and a storage device by the conveyor. Patent Document 3 discloses an apparatus for producing a large amount of granular iron by granulating molten iron with a water flow, dropping the liquid granular iron into water for cooling and solidification.

[0005] The granular iron is at a high temperature when it is put into water. Since the temperature of the granular iron is about 1200 - 1500 °C, when such high-temperature granular iron comes into contact with water, it enters a film boiling state where a steam film forms on the surface of the high-temperature object, and the water evaporates, taking away the heat of the granular iron. This film boiling has a low cooling capacity, for example, only about 1 / 100 of the heat transfer rate of nucleate boiling where no steam film occurs. Therefore, if the film boiling continues for a long time, the granular iron may not be sufficiently cooled, and the granular iron may fuse and combine with each other in the cooling water.

[0006] When the cooling water temperature is high, the water is likely to boil, so a steam film is likely to be maintained around the high-temperature object and it is likely to enter a film boiling state. Therefore, when the cooling water temperature increases, the cooling capacity of the granular iron significantly decreases, and the combination of the granular iron is likely to occur. To address such problems, Patent Document 3 states that by adjusting the cooling water volume of the secondary cooling water to maintain the cooling water temperature in the pit at 68 °C or lower, the combination of the granular iron deposited in the pit can be suppressed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] When producing granular iron from molten iron, considering that the droplets of molten iron spread horizontally to a certain extent and the installation space of the conveying device for the solidified granular iron, a cooling water tank of a considerably large size is required for cooling the granular iron. The cooling water tank is provided with a discharge port for supplying cooling water and a drain port for conveying the cooling water whose temperature has risen to the cooling facility, and thereby the cooling water is circulated between the cooling water tank and the cooling facility.

[0009] However, it is difficult to control so that cold cooling water is evenly distributed throughout the large cooling water tank. Patent Document 3 describes adjusting the cooling water volume of the secondary cooling water to maintain the cooling water temperature in the pit at 68°C or lower, but there is no description whatsoever regarding the method of controlling the flow in the cooling water tank, and depending on the flow of the cooling water, a stagnant region may occur in the cooling water tank. When the warm cooling water used for cooling the granular iron stays in this stagnant region, a region with a locally high water temperature may be formed. When a large amount of granular iron is charged into this region with a high water temperature, the film boiling state is maintained for a long time and the granular iron is not sufficiently cooled, and the granular iron fuses and combines with each other. When the granular iron combines with each other, the amount of granular iron in a size that is difficult to convey increases and the conveyance becomes difficult. There is a problem that when cooling water is contained when the granular iron combines with each other, it may cause a steam explosion.

[0010] In Patent Document 2, even if the surface of the granular iron is cooled and solidified by the time the granular iron is collected on the conveyor, the inside of the granular iron remains in an unfrozen high-temperature state. Since the granular iron is stacked in a dense state on the conveyor, when the amount of heat extraction from the surface of the granular iron by the cooling water decreases, the amount of heat transfer from the inside to the surface of the granular iron exceeds the amount of heat extraction from the surface of the granular iron by the cooling water, and reheating occurs in which the surface temperature of the granular iron rises. For this reason, there is a problem that the granular iron reheats while being conveyed on the conveyor, the surface temperature of the granular iron rises again, and the stacked granular iron easily fuses and combines with each other to form a large mass.

[0011] The present invention has been made to solve these problems, and an object thereof is to efficiently cool molten iron and also efficiently cool granular iron during conveyance in a conveying device such as a conveyor, and to suppress the combination of granular iron. It is to provide a granular iron manufacturing apparatus that can.

Means for Solving the Problems

[0012] The means for solving the above problems are as follows. [1] A granulation device that makes molten iron into droplets, a cooling water tank that cools the droplets by dropping them into cooling water to form granular iron, and a conveying device that conveys the granular iron outside the cooling water tank. The granulation device includes a water flow control container provided in the cooling water tank with openings at the upper and lower ends, and a group of cooling water pipes that supply cooling water into the water flow control container. The water flow control container has a partition cylinder body with an inclined surface whose horizontal cross-sectional area narrows downward, and a duct cylinder body connected to the lower part of the partition cylinder body. The group of cooling water pipes includes an upper-stage cooling water pipe group and a middle-stage cooling water pipe group connected to the partition cylinder body, and a lower-stage cooling water pipe group connected to the duct cylinder body. The upper-stage cooling water pipe group is connected to the upper stage of the inclined surface including the upper end of the partition cylinder body, and generates a cooling water flow along the inclined surface from top to bottom by the cooling water supplied from the upper-stage cooling water pipe group. The middle-stage cooling water pipe group is horizontally connected to the middle stage of the inclined surface of the partition cylinder body toward the core of the partition cylinder body. The cooling water supplied from the middle-stage cooling water pipe group flows toward the core of the partition cylinder body, converges at the core and rises, generating a first circulation flow that circulates in the partition cylinder body along with the cooling water flow along the inclined surface from top to bottom. The lower-stage cooling water pipe group is connected to the side surface of the duct cylinder body, and generates a second circulation flow that circulates in the duct cylinder body by the cooling water supplied from the lower-stage cooling water pipe group and the drainage from the partition cylinder body. The conveying device is provided below the water flow control container, and includes a conveyor that conveys the granular iron from inside the cooling water tank to outside the cooling water tank, and a cooling water supply device that supplies cooling water for cooling the granular iron carried out by the conveyor and provided above the conveyor in the cooling water tank. A granulation device for granular iron. [2] It has a control device for controlling the amount of cooling water supplied from the group of cooling water pipes to the water flow control container. The control device controls the amount of cooling water supplied from the group of cooling water pipes to decrease in the order of the middle-stage cooling water pipe group, the upper-stage cooling water pipe group, and the lower-stage cooling water pipe group. The granulation device for granular iron according to [1]. [3] The cooling water supply device supplies the cooling water to a region above the granular iron on the conveyor, and includes a main cooling water pipe provided along the conveying direction of the conveyor, and a plurality of cooling water header pipes arranged side by side in the conveying direction and each connected to the main cooling water pipe, extending in the width direction of the conveyor, and provided with at least one supply port in the width direction. The granular iron manufacturing apparatus according to [1] or [2]. [4] The granular iron manufacturing apparatus according to [1], wherein the upper stage cooling water pipe group and / or the middle stage cooling water pipe group has a protruding portion that covers an upper side of a connection portion connecting to the inclined surface. [5] The granular iron manufacturing apparatus according to [4], wherein a cross-sectional shape of the protruding portion is an inverted V shape or an inverted U shape that widens from above downward. [6] The granular iron manufacturing apparatus according to any one of [1], [4], and [5], wherein the upper stage cooling water pipe group has a protective cover that covers an upper side of a connection portion connecting to the inclined surface, and an upper end portion of the protective cover is closed. [7] The granular iron manufacturing apparatus according to [6], wherein a cross-sectional shape of the protective cover is a semi-circular or semi-elliptical shape that widens from above downward. [8] The granular iron manufacturing apparatus according to [3], wherein the supply port is a rectangular slit having a short side length of 3 mm or more. [Advantages of the Invention]

[0013] In the granular iron manufacturing apparatus of the present invention, a first circulation flow of cooling water from bottom to top is generated in the partition cylinder, and further, a second circulation flow of cooling water from bottom to top is generated in the duct cylinder, and the granular iron is cooled by the circulation flow. Thereby, the cooling efficiency of the granular iron in the partition cylinder and the duct cylinder is increased, and it is possible to suppress the fusion and combination of the granular iron with each other when cooling the granular iron. Further, in the granular iron manufacturing apparatus of the present invention, in a conveying device in which the granular iron is stacked and the granular iron is likely to be concentrated, the cooling water is supplied above the conveyed granular iron to cool the granular iron. Thereby, the granular iron can be efficiently cooled by replacing the cooling water in a limited area on the conveying device where the granular iron is collected, and it is possible to suppress the fusion and combination of the granular iron being conveyed by the conveying device with each other.

[0014] As described above, since the pig iron manufacturing apparatus of the present invention can manufacture pig iron by enhancing the cooling efficiency of pig iron, the amount of cooling water used can be reduced. Further, since the cooling efficiency of pig iron is high, if the cooling capacity of pig iron of the manufacturing apparatus is the same, the apparatus becomes more compact and the enlargement of the equipment can be suppressed. If the size of the manufacturing apparatus is the same, the apparatus can manufacture more pig iron.

Brief Description of the Drawings

[0015]

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[0016] Hereinafter, the present invention will be described through embodiments of the invention. The following embodiments show a preferred example of the present invention, and the present invention is not limited by these embodiments.

[0017] FIG. 1 is a schematic cross-sectional view of a granular iron manufacturing apparatus 70 according to the present embodiment. The granular iron manufacturing apparatus 70 is an apparatus that cools and solidifies molten iron such as molten iron or molten steel in a state where it is made into droplets to produce granular iron, which is a granular iron material. The granular iron manufacturing apparatus 70 includes a granulating apparatus 10 that forms molten iron into droplets, a cooling water tank 20, a water flow control container 30, a cooling water pipe group 40, and a conveying apparatus 50.

[0018] The granulating apparatus 10 includes a tundish 12 (such as a molten iron ladle) that houses molten iron 60 and is provided with a nozzle 16 for discharging molten iron at the bottom, and a molten iron receiving plate 14 that collides with the liquid column 62 of the molten iron flowing down after being discharged from the nozzle 16. The molten iron receiving plate 14 is composed of a disk-shaped refractory and is supported by a support 18. The liquid column 62 of the molten iron flowing down from the nozzle 16 collides with the molten iron receiving plate 14, and droplets 64 of the molten iron 60 scatter around it.

[0019] When the droplets 64 of the molten iron 60 become large, the heat capacity increases and it takes time for solidification. There is a risk that the molten iron 60 remains at a high temperature and fuses with each other in the water flow control container 30 to form a large mass, making it difficult to be transported by the transport device 50. For this reason, it is preferable that the granulation device 10 makes the droplets 64 of the molten iron 60 such that the maximum length of the granulated iron 66 after cooling is 50 mm or less. The molten iron 60 is made into droplets 64 by the granulation device 10 and falls into the cooling water 24. Further, in the granulation device 10, the flow rate of the molten iron 60 from the tundish 12 is controlled so that the droplets 64 fall into the region where the water flow control container 30 is provided.

[0020] The cooling water tank 20 houses the cooling water 24 and the water flow control container 30. The water flow control container 30 is installed in the cooling water 24 housed in the cooling water tank 20. The cooling water 24 housed in the cooling water tank 20 may include the cooling water 24 drained from the water flow control container 30. The cooling water 24 housed in the cooling water tank 20 is drained from the drain port 22 in an amount equal to the amount of the supplied cooling water so that the cooling water surface of the cooling water tank 20 becomes constant. By using a large-capacity cooling water tank 20, it becomes easy to control the cooling water surface, and the production of granulated iron by the granulated iron production device 70 becomes stable.

[0021] The water flow control container 30 is provided inside the cooling water tank 20 at a position where it receives the molten iron 60 made into droplets 64 by the granulation device 10. The water flow control container 30 cools and solidifies the droplets 64 with the cooling water 24 housed inside to form granulated iron 66.

[0022] The water flow control container 30 includes a partition cylinder 32 having an inclined surface 34 inclined such that the horizontal cross-sectional area becomes narrower downward, and a duct cylinder 35 connected to the lower part of the partition cylinder 32. An inlet 33 for receiving droplets 64 is provided at the upper end of the partition cylinder 32, and an outlet 36 for discharging granular iron 66 is provided at the lower end of the duct cylinder 35. That is, the upper and lower ends of the water flow control container 30 are open. The inclined surface 34 may be formed inside the water flow control container 30, and the outer shape of the water flow control container 30 is not particularly limited. The inclination angle of the inclined surface 34 with respect to the horizontal plane is preferably within the range of 40 to 60° from the viewpoint of not retaining the granular iron 66. In the example shown in FIG. 1, an example in which the upper end side of the partition cylinder 32 does not have a cylindrical portion is shown, but a cylindrical portion may be provided on the upper end side of the partition cylinder 32.

[0023] In this embodiment, the cooling region of the granular iron 66 formed by the water flow control container 30 is defined as a cooling region A. By providing the cooling region A formed by the water flow control container 30 in this way, the following effects (1) and (2) can be obtained. (1) By concentrating and introducing the cooling water 24 into the cooling region A, the granular iron 66 can be efficiently cooled. (2) Since the granular iron 66 generated in the partition cylinder 32 is collected at one location on the inclined surface 34, the recovery of the granular iron 66 becomes easy.

[0024] The cooling water pipe group 40 is a group of water pipes through which the cooling water 24 cooled to 0°C or higher and 35°C or lower by cooling equipment such as a heat exchanger or a cooling tower (not shown) passes. When the cooling water 24 is supplied from the cooling water pipe group 40 into the partition cylinder body 32 of the water flow control container 30, the cooling water 24 tends to flow upward with a large opening. Therefore, when the cooling water is supplied from the lower part of the partition cylinder body 32 toward the cylinder core, the cooling water converges at the cylinder core in the partition cylinder body 32 and rises. On the other hand, when the cooling water 24 is supplied from above the partition cylinder body 32 along the inclined surface 34 downward, the cooling water 24 that converges at the cylinder core in the partition cylinder body 32 and rises does not flow out into the cooling water tank 20 from the inlet 33 of the partition cylinder body 32, but spreads in the circumferential direction near the inlet 33. The cooling water 24 that spreads in the circumferential direction generates a first circulation flow accompanied by a cooling water flow descending the inclined surface 34 of the partition cylinder body 32. By generating this first circulation flow, the granular iron 66 can be cooled in a countercurrent manner, and the stagnant region in the partition cylinder body 32 can be reduced. The cooling water pipe group 40 includes an upper-stage cooling water pipe group 44 and a middle-stage cooling water pipe group 46 connected to the partition cylinder body, and a lower-stage cooling water pipe group 48 connected to the duct cylinder body 35.

[0025] The middle-stage cooling water pipe group 46 is horizontally connected toward the cylinder core of the partition cylinder body 32 at the middle stage of the inclined surface 34 in the range from the center in the vertical direction of the partition cylinder body 32 to 650 mm below. When the cooling water 24 is supplied from the middle-stage cooling water pipe group 46 into the partition cylinder body 32, the cooling water 24 heads toward the cylinder core of the partition cylinder body 32, converges at the cylinder core, and rises. The cooling water 24 that converges at the cylinder core and rises spreads in the circumferential direction at the upper end of the partition cylinder body 32 and flows along the inclined surface 34 downward, forming a first circulation flow. The cooling water 24 supplied from the middle-stage cooling water pipe group 46 forms a part of the first circulation flow.

[0026] The amount of cooling water supplied from the middle-stage cooling water pipe group 46 is 3 1500 m 3 / h or more and 3900 m 3 / h or less is preferable. If the amount of cooling water is less than 1500 m 3If it is more than / h, it deviates from the first circulation flow, and cooling water 24 flowing out from the inlet 33 of the partition cylinder 32 into the cooling water tank 20 is generated, which is not preferable.

[0027] The flow velocity of the cooling water 24 supplied from the middle-stage cooling water pipe group 46 is preferably 1.8 m / s or more and 2.2 m / s or less. If the flow velocity of the cooling water 24 supplied from the middle-stage cooling water pipe group 46 is slower than 1.8 m / s, the cooling water 24 will decelerate before reaching the core of the partition cylinder 32, and it is not preferable because a strong and stable upward flow is difficult to generate. If the flow velocity of the cooling water 24 supplied from the middle-stage cooling water pipe group 46 is faster than 2.2 m / s, the pressure loss in the cooling water pipe 41 will increase, and large-scale water supply equipment such as a pump is required, which is not preferable.

[0028] The upper-stage cooling water pipe group 44 is connected to the upper stage of the inclined surface 34 including the upper end of the partition cylinder 32. The upper-stage cooling water pipe group 44 covers the upper-stage portion of the partition cylinder 32 including a slit 42 having a predetermined gap at the peripheral edge of the upper end of the partition cylinder 32 and a water supply port 43 on the inclined surface 34 of the upper stage of the partition cylinder 32, and is connected to a water supply jacket 45 that supplies cooling water to the slit 42 and the water supply port 43. The upper-stage cooling water pipe group 44 is connected to the inclined surface 34 including the upper end of the partition cylinder 32 in the range from the upper end of the partition cylinder 32 downward by 1000 mm.

[0029] The flow velocity of the cooling water 24 supplied from the slit 42 and the water supply port 43 is preferably 0.1 m / s or more and 0.7 m / s or less. When the cooling water 24 is supplied into the partition cylinder 32 from the slit 42 and the water supply port 43 at a flow velocity within this range, the cooling water 24 does not flow toward the core of the partition cylinder 32, but flows along the inclined surface 34 downward from the upper end of the inclined surface 34. As a result, the cooling water 24 supplied from the upper-stage cooling water pipe group 44 comes to form a part of the first circulation flow, and the first circulation flow is stabilized. The amount of cooling water supplied from the upper-stage cooling water pipe group 44 is preferably 700 m 3 / h or more and 3000 m 3 / h or less. When the amount of cooling water supplied from the upper-stage cooling water pipe group 44 is 700 m 3If it is less than / h, there is a risk that the first circulation flow cannot be stabilized, which is not preferable. The amount of cooling water supplied from the upper cooling water pipe group 44 is 3000 m 3 If it is more than / h, the effect of stabilizing the first circulation flow saturates, does not contribute to the cooling of the granular iron 66, but only descends along the inclined surface 34 and is drained from the drain port 22 at the lower end of the partition cylinder body 32, which is not preferable. The distribution of the amount of cooling water supplied from the slit 42 and the water supply port 43 is preferably 6:4.

[0030] The lower cooling water pipe group 48 has at least one set of water pipes horizontally connected to the side surface of the duct cylinder body 35 facing the core of the duct cylinder body 35. When the cooling water 24 is supplied into the duct cylinder body 35 from the lower cooling water pipe group 48, the cooling water 24 heads toward the core of the duct cylinder body 35, converges at the core and rises, generating a second circulation flow that circulates in the duct cylinder body 35.

[0031] The amount of cooling water supplied from the lower cooling water pipe group 48 is 250 m 3 / h or more and 750 m 3 / h or less is preferable. If the amount of cooling water supplied from the lower cooling water pipe group 48 is less than 250 m 3 / h, it is difficult to generate the second circulation flow in the duct cylinder body 35, and there is a risk of generating a stagnant region with a high water temperature, which is not preferable. If the amount of cooling water supplied from the lower cooling water pipe group 48 is more than 750 m 3 / h, it will hinder the drainage from the lower end of the partition cylinder body 32, which is not preferable.

[0032] The flow rate of the cooling water 24 supplied from the lower cooling water pipe group 48 is preferably 0.5 m / s or more and 1.0 m / s or less. If the flow rate of the cooling water 24 supplied into the duct cylinder body 35 is slower than 0.5 m / s, the effect of stirring in the duct cylinder body 35 will be low, which is not preferable. If the flow rate of the cooling water 24 supplied into the duct cylinder body 35 is faster than 1.0 m / s, the leakage from the gap between the lower end of the duct cylinder body 35 and the conveying device 50 will increase, which is not preferable.

[0033] FIG. 2 is a schematic cross-sectional view of the water flow control container 30 at the portion where the cooling water pipe group is connected. FIG. 2(a) is a schematic cross-sectional view of the water flow control container 30 at the portion where the upper cooling water pipe group 44 is connected, and FIG. 2(b) is a schematic cross-sectional view of the water flow control container 30 at the portion where the middle cooling water pipe group 46 is connected. FIG. 2(c) is a schematic cross-sectional view of the water flow control container 30 at the portion where the lower cooling water pipe group 48 is connected.

[0034] As shown in FIG. 2(a), the upper cooling water pipe group 44 is composed of two cooling water pipes 41. The cooling water 24 is supplied from the two cooling water pipes 41 to the water supply jacket 45, and is distributed by the water supply jacket 45 to the annular slit 42 and the 16 water supply ports 43 radially arranged on the inclined surface 34 of the partition cylinder body 32. The cooling water 24 is supplied into the partition cylinder body 32 from the annular slit 42 and the 16 water supply ports 43. The middle cooling water pipe group 46 is composed of four cooling water pipes 41 horizontally arranged toward the core of the partition cylinder body 32. The cooling water 24 is supplied into the partition cylinder body 32 from the four cooling water pipes 41. The lower cooling water pipe group 48 is composed of four cooling water pipes 41. Among the four, two cooling water pipes 41 are horizontally arranged facing each other toward the core of the duct cylinder body 35, and the other two cooling water pipes 41 are arranged on the side surface of the duct cylinder body. The cooling water 24 is supplied into the duct cylinder body 35 from the four cooling water pipes 41. Thus, in the pig iron manufacturing apparatus 70 according to the present embodiment, cooling water is supplied into the partition cylinder body 32 and the duct cylinder body 35 by a total of ten cooling water pipes 41. In the example shown in FIG. 2, an example where the cross-sectional shape of the duct cylinder body 35 is quadrangular is shown, but it is not limited thereto, and the cross-sectional shape of the duct cylinder body 35 may be circular.

[0035] FIG. 3 is a schematic cross-sectional view for explaining the circulation flow generated in the partition cylinder 32 and the duct cylinder 35. The first circulation flow B1 is a circulation flow that circulates within the partition cylinder 32. The cooling water 24 supplied from the middle-stage cooling water pipe group 46 merges at the cylinder core, forming a strong upward flow. This strong upward flow spreads to the peripheral part near the inlet 33. The water flow that has spread to the peripheral part becomes a downward flow that descends along the inclined surface 34. The downward flow merges with the cooling water flow from the slit 42 and the water supply port 43, and due to the rectifying action of these cooling water flows, it flows downward along the inclined surface 34 and is discharged from the lower end connected to the duct cylinder 35. Due to the first circulation flow B1 in the partition cylinder 32, the water temperature in the region from the middle stage to the upper stage in the cooling region A can be maintained at an appropriate water temperature of around 50°C. The strong upward flow generated in the core part of the partition cylinder 32 is countercurrent to the granular iron 66 that is introduced from the inlet 33 and descends, so the granular iron 66 can be cooled with high cooling efficiency.

[0036] The second circulation flow B2 is a circulation flow that occurs within the duct cylinder 35. The drainage from the lower end of the partition cylinder 32 merges with the discharge flow of low water temperature from the lower-stage cooling water pipe group 48 and is agitated, thereby generating a circulation flow within the duct cylinder 35. As a result, the granular iron collected by the partition cylinder 32 can be efficiently cooled.

[0037] In this way, by generating the first circulation flow B1 in the partition cylinder 32 and the second circulation flow B2 in the duct cylinder 35, the cooling water within the partition cylinder 32 and the duct cylinder 35 is agitated, and the generation of stagnant regions within the partition cylinder 32 and the duct cylinder 35 is suppressed. As a result, the local temperature rise of the cooling water 24 within the partition cylinder 32 and the duct cylinder 35 is suppressed, and the granular iron 66 can be efficiently cooled. As a result, it is possible to suppress the granular iron 66 from not being sufficiently cooled and the granular iron from fusing and combining with each other.

[0038] The upward flow generated in the core of the partition cylinder 32 becomes a cooling water flow that opposes the granular iron 66 that is introduced from the inlet 33 and falls, so high cooling efficiency can be obtained. In order to preferably form this upward flow, it is preferable that the total amount of cooling water supplied from the middle-stage cooling water pipe group 46 is larger than the total amount of cooling water supplied from the upper-stage cooling water pipe group 44.

[0039] The cooling water flow supplied from the upper-stage cooling water pipe group 44 connected to the upper stage of the inclined surface 34 of the partition cylinder body 32 descends along the inclined surface 34, so it collides with the discharge flow from the middle-stage cooling water pipe group 46 connected to the middle stage of the inclined surface 34 of the partition cylinder body 32. For this reason, if the amount of cooling water supplied from the upper-stage cooling water pipe group 44 is larger than the amount of cooling water supplied from the middle-stage cooling water pipe group 46, there is a concern that the flow of water discharged from the middle-stage cooling water pipe group 46 will be weakened by the flow of the cooling water, and it will be difficult to form the first circulation flow B1. Therefore, it is preferable that the total amount of cooling water supplied from the middle-stage cooling water pipe group 46 is larger than the total amount of cooling water supplied from the upper-stage cooling water pipe group 44. Furthermore, it is more preferable that the total amount of cooling water supplied from the middle-stage cooling water pipe group 46 is about four times the total amount of cooling water supplied from the upper-stage cooling water pipe group 44.

[0040] It is preferable that the total amount of cooling water supplied from the lower-stage cooling water pipe group 48 connected to the duct cylinder body 35 is smaller than the total amount of cooling water supplied from the upper-stage cooling water pipe group 44. If the total amount of cooling water supplied from the lower-stage cooling water pipe group 48 becomes larger than the total amount of cooling water supplied from the upper-stage cooling water pipe group 44, there is a concern that the drainage from the lower end of the partition cylinder body 32 to the duct cylinder body 35 will be inhibited, and the temperature inside the partition cylinder body 32 will be increased conversely. Therefore, it is preferable that the total amount of cooling water supplied from the lower-stage cooling water pipe group 48 is smaller than the total amount of cooling water supplied from the upper-stage cooling water pipe group 44. Furthermore, it is more preferable that the total amount of cooling water supplied from the lower-stage cooling water pipe group 48 is about 1 / 2 of the total amount of cooling water supplied from the upper-stage cooling water pipe group 44.

[0041] In order to suitably generate the first circulation flow B1 and suppress an undesired increase in the temperature within the partition cylinder 32, it is preferable to reduce the total amount of cooling water supplied from each cooling water pipe group in the order of the middle-stage cooling water pipe group 46, the upper-stage cooling water pipe group 44, and the lower-stage cooling water pipe group 48. Thus, it is preferable to control the total amount of cooling water supplied from each cooling water pipe group as described above. For this reason, the sponge iron manufacturing apparatus 70 according to the present embodiment preferably further includes a control device that controls the total amount of cooling water supplied from the upper-stage cooling water pipe group 44, the middle-stage cooling water pipe group 46, and the lower-stage cooling water pipe group 48. The control device is constituted by a general-purpose computer and controls the supply amount of the cooling water 24 sent to each cooling water pipe group by controlling cooling facilities such as heat exchangers and cooling towers (not shown).

[0042] The sponge iron 66 cooled within the water flow control container 30 is discharged from a discharge port 36 provided at the lower part of the water flow control container 30. The discharged sponge iron 66 is conveyed outside the cooling water tank 20 by a conveying device 50.

[0043] FIG. 4 is a schematic view showing a part of the conveying device 50. FIG. 4(a) is a side cross-sectional schematic view showing a part of the conveying device 50. FIG. 4(b) is a top schematic view showing a part of the water flow control container 30 and the conveying device 50. The conveying device 50 conveys the sponge iron 66 discharged from the discharge port 36 outside the cooling water tank 20. The conveying device 50 includes a conveyor 52 that conveys the sponge iron 66 outside the cooling water tank 20, and a cooling water supply device 54 provided above the conveyor 52.

[0044] The sponge iron 66 discharged from the discharge port 36 is stacked on the conveyor 52. The conveyor 52 conveys the stacked sponge iron 66 outside the cooling water tank 20. The conveyor 52 is preferably a mesh conveyor so that the cooling water is not conveyed outside the cooling water tank 20 as the sponge iron 66 is conveyed.

[0045] The cooling water supply device 54 includes a main cooling water pipe 56 provided along the conveying direction of the conveyor 52 and a plurality of cooling water header pipes 57. The main cooling water pipe 56 is a water pipe that supplies the cooling water cooled by cooling facilities such as a heat exchanger and a cooling tower to the cooling water header pipes 57. The cooling water header pipes 57 are water pipes extending in the width direction of the conveyor 52. A plurality of rectangular slits 58 are provided in the cooling water header pipes 57 in the width direction, and the cooling water is supplied from the slits 58. The rectangular slit 58 is an example of a supply port. The supply port may be a rectangular slit having the same length as the longitudinal length of the cooling water header pipe 57 extending in the width direction, or may be a plurality of circular pipe nozzles arranged in the longitudinal direction. That is, at least one supply port may be provided in the width direction of the conveyor 52.

[0046] The rectangular slit 58 is preferably sized such that clogging due to sludge mixed in the cooling water is unlikely to occur. Since the size of the sludge mixed in the cooling water is about 1 to 2 mm, the length of the short side of the slit 58 is preferably 3 mm or more. The length of the long side of the slit 58 may be determined to ensure a cooling water supply rate of 2 to 3 m / sec.

[0047] The plurality of cooling water header pipes 57 are provided side by side in the conveying direction of the conveyor 52 and are each connected to the main cooling water pipe 56. The space 59 from which the cooling water is supplied from the slit 58 of the cooling water header pipe 57 is above the granular iron 66 on the conveyor 52 and is a region sandwiched between the conveyor 52 and the cooling water supply device 54. In this region, the cooling water that has become hot by cooling the granular iron 66 discharged from the water flow control container 30 stays. Therefore, by using the cooling water supply device 54 to supply the cooling water to the space 59, convection of the cooling water is generated in the space 59, and the hot cooling water is discharged from the space 59. Thereby, the water temperature of the cooling water around the granular iron 66 conveyed by the conveyor 52 can be kept low, the granular iron 66 stacked on the conveyor 52 is cooled, and it is possible to suppress the surface temperature of the granular iron 66 from rising due to reheating and the granular iron 66 from fusing and coalescing with each other.

[0048] Since the granular iron 66 collected on the conveyor 52 can be cooled by supplying cooling water to a limited area above the conveyor 52, it is not necessary to convect the cooling water in the entire cooling water tank 20, and the granular iron 66 can be efficiently cooled with a small amount of cooling water.

[0049] Since the surface temperature of the granular iron 66 discharged from the discharge port 36 is around 800 °C, the surface of the granular iron 66 is covered by a steam film. If low-temperature cooling water is directly injected onto the granular iron 66 and the steam film is broken and the low-temperature cooling water comes into direct contact with the surface of the granular iron 66, a steam explosion, which is explosive boiling, may occur. Therefore, in order to stably cool the granular iron 66, it is preferable not to directly inject low-temperature cooling water onto the granular iron 66 and to maintain the temperature of the cooling water around the granular iron 66 in the range of 40 °C to 65 °C, and more preferably in the range of 45 to 60 °C. When the water temperature exceeds 65 °C, the water is likely to boil, so it is easy to maintain a steam film around the high-temperature object and it is likely to become film boiling, and the cooling capacity of the granular iron is significantly reduced. If it is below 40 °C, the steam film covering the surface of the granular iron 66 becomes unstable, and there is a concern that a steam explosion may occur, which is not preferable.

[0050] The cooling water supply device 54 is provided with a plurality of cooling water header pipes 57 provided with a plurality of slits 58 in the width direction of the conveyor 52 at intervals in the conveying direction of the conveyor 52. In this way, cooling water is supplied from a large number of slits 58 of the plurality of cooling water header pipes 57 provided along the conveying direction of the conveyor 52 to the space 59. Thereby, while suppressing the amount of cooling water supplied from each slit 58 to be small and suppressing the cooling water from being directly injected onto the granular iron 66, it is possible to generate convection of the cooling water in the space 59.

[0051] The supply speed of the cooling water supplied from the rectangular slit 58 is preferably in the range of 2 m / sec or more and 3 m / sec or less. By setting the supply speed of the cooling water in the range of 2 m / sec or more and 3 m / sec or less, it is possible to suppress an increase in the pressure loss in the cooling water header pipe 57 and the cooling water main pipe 56, and to generate convection of the cooling water in the space 59 to discharge the heated cooling water from the space 59.

[0052] The amount of cooling water supplied from the cooling water header pipe 57 may be such that cooling water with a volume approximately 10 times the volume of at least the space 59 can be supplied during the time from when the granular iron 66 is conveyed by the conveying device 50 until it is conveyed out of the cooling water tank 20. The supply amount of this cooling water is determined from the simulation results described later.

[0053] It is preferable that the distance between the cooling water header pipes 57 is set to be approximately the same length as the distance between the cooling water header pipe 57 and the granular iron 66 conveyed on the conveyor 52. Thereby, the retention of cooling water between the cooling water header pipes 57 is suppressed, and the cooling water temperature in the space 59 can be evenly lowered. The water temperature of the cooling water supplied from the cooling water header pipe 57 is preferably within the range of 30°C or higher and 45°C or lower. When the water temperature of the cooling water supplied from the cooling water header pipe 57 is lower than 30°C and the supplied cooling water directly touches the surface of the granular iron 66, there is a concern that a steam explosion, which is an explosive boiling phenomenon, may occur, which is not preferable. When the water temperature of the cooling water exceeds 45°C, the cooling effect of the granular iron 66 decreases, which is not preferable.

[0054] FIG. 5 is a schematic cross-sectional view showing another water flow control container 80 used in the granular iron manufacturing apparatus according to the present embodiment. In the water flow control container 80 shown in FIG. 5, the same components as those of the water flow control container 30 shown in FIG. 1 are given the same reference numerals, and the description thereof is omitted. The water flow control container 80 shown in FIG. 5 is different from the water flow control container 30 shown in FIG. 1 in that it has a protruding portion 90.

[0055] If a water supply port 43 for supplying cooling water 24 is provided on the inclined surface 34 of the partition cylinder body 32, there is a concern that the granular iron 66 falling along the inclined surface 34 may enter the water supply port 43 and block the water supply port 43. For this reason, it is preferable to provide a protruding portion 90 that covers the upper side of the connection portion of the water supply port 43 and / or the middle-stage cooling water pipe group 46 with the inclined surface. Here, covering the upper side of the connection portion of the water supply port 43 and the middle-stage cooling water pipe group 46 means providing the protruding portion 90 to a position where the connection portion of the water supply port 43 and the middle-stage cooling water pipe group 46 is hidden in a top view. The protruding portion 90 is preferably provided so as to protrude horizontally from the inclined surface 34 toward the inside of the partition cylinder body 32 so as not to impede the flow of the supplied cooling water 24.

[0056] FIG. 6 is a schematic view of the water supply port 43 provided with the protruding portion as viewed from the horizontal direction. FIG. 6(a) shows an inverted V-shaped protruding portion 90, and FIG. 6(b) shows an inverted U-shaped protruding portion 91. As shown in FIG. 6(a), the cross-sectional shape of the protruding portion 90 is preferably an inverted V shape that protrudes upward and is inclined so as to widen downward. By making the cross-sectional shape of the protruding portion 90 an inverted V shape, it is possible to suppress the intrusion of the granular iron 66 into the water supply port 43 while suppressing the deposition of the granular iron 66 on the upper surface of the protruding portion 90.

[0057] Instead of the protruding portion 90, a protruding portion 91 having an inverted U-shaped cross-sectional shape may be provided. By providing the protruding portion 91 having an inverted U-shaped cross-sectional shape in this way, it is possible to suppress the intrusion of the granular iron 66 into the water supply port 43 while suppressing the deposition of the granular iron 66 on the upper surface of the protruding portion 91.

[0058] FIG. 7 is a cross-sectional schematic view showing another water flow control container 82 used in the granular iron manufacturing apparatus according to the present embodiment. In the water flow control container 82 shown in FIG. 7, the same components as those of the water flow control container 80 shown in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted. The water flow control container 82 shown in FIG. 7 is different from the water flow control container 80 shown in FIG. 5 in that it has a protective cover 92.

[0059] As described above, when the water supply port 43 is provided, there is a concern that the granular iron 66 falling along the inclined surface 34 may enter the water supply port 43 and block the water supply port 43. In particular, since the granular iron 66 in the upper part of the partition cylinder body 32 is still in a molten state, if it adheres to the inside of the water supply port 43, it will be difficult to remove. For this reason, it is more preferable to provide a protective cover 92 that covers the upper side of the water supply port 43. Here, covering the upper side of the water supply port 43 means providing the protective cover 92 to a position where the water supply port 43 is hidden in a top view. The protective cover 92 is preferably provided at a position where the water supply port 43 is not hidden when the water supply port 43 is viewed from the horizontal direction so as not to obstruct the flow of the cooling water 24 supplied from the water supply port 43. Furthermore, the protective cover 92 also covers the inclined surface 34 above the water supply port 43 along the inclination direction of the inclined surface 34. The upper end portion of the protective cover 92 is preferably structured to be closed so that the scattered droplets 64 do not enter the protective cover 92, and the inclination angle of the protective cover 92 is preferably the same as the angle of the inclined surface 34.

[0060] FIG. 8 is a schematic view of the water supply port 43 provided with the protective cover 92 viewed from the horizontal direction. As shown in FIG. 8, the cross-sectional shape of the protective cover 92 is preferably a semi-circular or semi-elliptical shape that expands downward. By making the cross-sectional shape of the protective cover 92 a semi-circular or semi-elliptical shape, it is possible to suppress the intrusion of the granular iron 66 into the water supply port 43 while suppressing the deposition of the granular iron 66 on the upper surface of the protective cover 92.

[0061] In the water flow control containers 80 and 82, an example in which the protruding portion 90 or the protective cover 92 is provided for the water supply port 43 is shown, but it is not limited to this, and both the protruding portion 90 and the protective cover 92 may be provided for the water supply port 43. Even with such a configuration, it is possible to suppress the intrusion of the granular iron 66 into the water supply port 43.

[0062] As described above, in the granular iron manufacturing apparatus 70 according to the present embodiment, a first circulation flow B1 of the cooling water 24 flowing upward from below in the partition cylinder 32 is generated, and further, a second circulation flow B2 of the cooling water 24 flowing upward from below in the duct cylinder 35 is generated. In the granular iron manufacturing apparatus 70 according to the present embodiment, the granular iron 66 is cooled by these two circulation flows to manufacture the granular iron 66 from the molten iron 60. Since the first circulation flow B1 is a countercurrent to the falling direction of the granular iron 66, the granular iron 66 can be efficiently cooled by the first circulation flow B1. Further, since the partition cylinder 32 and the duct cylinder 35 are agitated by the circulation flows B1 and B2, the generation of stagnant regions in the partition cylinder 32 and the duct cylinder 35 is suppressed. As a result, the cooling effect of the granular iron is enhanced, and the fusion and coalescence of the granular iron during cooling are suppressed.

[0063] Furthermore, since the granular iron manufacturing apparatus 70 according to the present embodiment has the transport device 50 provided with the cooling water supply device 54, the granular iron 66 can be efficiently cooled by replacing the cooling water in the limited area on the transport device 50 where the granular iron 66 is collected. By cooling the granular iron 66 in this way, the fusion and coalescence of the granular iron 66 transported by the conveyor 52 can be suppressed. Further, since the cooling efficiency of the granular iron 66 by the cooling water is also enhanced, the amount of cooling water used can be reduced and the enlargement of the equipment can be suppressed.

Example

[0064] [Example 1] Next, the results of the simulation for confirming the granular iron cooling effect by the granular iron manufacturing apparatus according to the present embodiment as Example 1 will be described. A cooling water supply model having the same configuration as the water flow control container 30 disposed in the cooling water tank 20 shown in FIG. 1 was produced, and the water temperature distribution of the cooling water in and around the water flow control container was simulated using the model. The falling speed and heat quantity of the granular iron in the water and on the inclined surface in the partition cylinder were measured by the experiment performed in advance, and the position distribution and heat generation amount of the granular iron in the partition cylinder and the duct cylinder were modeled.

[0065] In the simulation results, if the cooling water temperature inside the partition cylinder, inside the duct cylinder, and in the surroundings is 70°C or lower, and furthermore, if the temperature of the granular iron is cooled to 650°C or lower when it accumulates on the conveying device, it was determined that the granular iron was effectively cooled.

[0066] FIG. 9 is a diagram showing the simulation conditions of Invention Example 1 and Invention Example 2. FIG. 10 is a diagram showing the simulation conditions of Comparative Example 1 and Comparative Example 2. The cooling water supply models of Invention Example 1, Invention Example 2, Comparative Example 1, and Comparative Example 2 were set according to the piping layout, number of pipes, flow rate distribution of cooling water, and pipe diameter (nominal diameter (A)) shown in FIGS. 9 and 10, and simulations were carried out. The cooling water pipe layout of Invention Example 1 is the same as the cooling water pipe layout of the water flow control container 30 shown in FIG. 2.

[0067] The cooling water pipe layout of Invention Example 2 is the same as the cooling water pipe layout of Invention Example 1, except that there is one cooling water pipe connected to the water supply jacket of the upper-stage cooling water pipe group, and there is one less pipe connected to the side surface of the duct cylinder of the lower-stage cooling water pipe group than in Invention Example 1. In Invention Example 2, the total amount of cooling water supplied from the middle-stage cooling water pipe group was set to about 40% of that in Invention Example 1, the amount of cooling water supplied from the upper-stage cooling water pipe group was set to 3 times that in Invention Example 1, and the total amount of cooling water supplied from the cooling water pipe group was the same as that in Invention Example 1, and a model with the flow rate distribution of the cooling water changed was used.

[0068] In Comparative Example 1, a model was used in which the upper-stage cooling water pipe group and the lower-stage cooling water pipe group were eliminated, and cooling water was supplied only by the middle-stage cooling water pipe group. In Comparative Example 2, the number of pipes in the middle-stage cooling water pipe group and the lower-stage cooling water pipe group was set to half or less of that in Invention Example 1, the amount of cooling water supplied was halved, the amount of cooling water supplied from the upper-stage cooling water pipe group was set to 2 times that in Invention Example 1, and a model with the flow rate distribution of the cooling water changed was used. The two pipes of the middle-stage cooling water pipe group were connected to an inclined surface at a point-symmetrical position with respect to the center of the horizontal cross-section of the partition cylinder so that the central axes of the respective cooling water pipes were parallel.

[0069] Other simulation conditions common to Invention Example 1, Invention Example 2, Comparative Example 1, and Comparative Example 2 are as follows. (1) Temperature of molten iron: 1500 °C (2) Outflow rate of molten iron from tundish: 450 ton / h (3) Water temperature of cooling water: 35 °C (4) Inclination angle of inclined surface of partition cylinder: 56° (5) Outlet diameter of partition cylinder: φ1560 mm (6) Height of partition cylinder: 3300 mm (7) Height of inclined surface of partition cylinder: 3291 mm (length of inclined surface: 3970 mm)

[0070] Figure 11 is a diagram showing the simulation results of Invention Example 1 and Invention Example 2. As shown in Invention Example 1 of Figure 11, the cooling water temperature in the water flow control container became 52 to 69 °C, achieving the target of 70 °C or less. Furthermore, the temperature when granular iron was deposited on the conveying device was at most 550 °C, also achieving the target of 650 °C or less for the granular iron temperature.

[0071] Figure 12 is a perspective schematic diagram showing the water flow of the cooling water supplied from each cooling water pipe group in Invention Example 1. Figure 12(a) is a perspective schematic diagram showing the water flow of the cooling water supplied from the upper-stage cooling water pipe group. Figure 12(b) is a perspective schematic diagram showing the water flow of the cooling water supplied from the middle-stage cooling water pipe group. Figure 12(c) is a perspective schematic diagram showing the water flow of the cooling water supplied from the lower-stage cooling water pipe group. As shown in Figures 12(a) and (b), in the invention example, it was confirmed that a first circulation flow was generated inside the partition cylinder. From Figure 12(c), in the invention example, it was confirmed that a second circulation flow was generated inside the duct cylinder.

[0072] Referring again to Fig. 11, in Invention Example 2, although the cooling water volume from the middle-stage cooling water pipe group was reduced to 40%, an upward flow occurred in the cylinder core. And a strong water flow descending along the inclined surface of the partition cylinder body from the upper-stage cooling water pipe group occurred particularly on the side (right side of the paper surface) where the cooling water pipe was connected to the water supply jacket. As a result, the first circulation flow was stabilized, the cooling water was agitated, the cooling water temperature in the water flow control container was maintained at 70°C or lower, and the target of 70°C or lower was achieved. Furthermore, the temperature when the granular iron was deposited on the conveying device was at most 646°C, and the target of 650°C or lower for the granular iron temperature was also achieved. Comparing the temperatures when the granular iron in Invention Example 1 and Invention Example 2 was deposited on the conveying device, Invention Example 1, in which the total cooling water volume supplied from the middle-stage cooling water pipe group was larger than the total cooling water volume supplied from the upper-stage cooling water pipe group, was about 100°C lower. From this result, it was confirmed that the granular iron can be cooled with high cooling efficiency by making the total cooling water volume supplied from the middle-stage cooling water pipe group larger than the total cooling water volume supplied from the upper-stage cooling water pipe group.

[0073] Fig. 13 is a diagram showing the simulation results of Comparative Example 1 and Comparative Example 2. As shown in Fig. 13, in Comparative Example 1, since a large amount of cooling water was supplied from the middle-stage cooling water pipe group, a strong upward flow occurred. The cooling water was agitated by the upward flow, and the cooling water temperature at the central part of the partition cylinder body was maintained at 70°C or lower. However, at the upper and lower parts of the partition cylinder body, the cooling water was not agitated, and stagnation occurred in the cooling water in that area. As a result, the temperature when the granular iron was deposited on the conveying device was 652°C, slightly exceeding the target of 650°C or lower.

[0074] In Comparative Example 2, two pipes of the middle-stage cooling water pipe group were connected to the partition cylinder such that the central axes of the respective cooling water pipes were parallel to the inclined surfaces at positions that were point-symmetrical with respect to the center of the horizontal cross-section of the partition cylinder. Therefore, unlike Invention Example 1 and Comparative Example 1, a strong upward flow near the cylinder core did not occur, and instead, a swirling flow that rose while swirling inside the partition cylinder occurred. The water temperature inside the partition cylinder of Comparative Example 2 was lower than that of Invention Example 1 and Comparative Example 1. This indicates that the heat of the granular iron was not taken away, and the temperature when the granular iron was deposited on the conveying device reached a maximum of 700°C, greatly exceeding the target of 650°C or less, and the variation in the granular iron temperature also became large, ranging from 460°C to 700°C. From the above simulation results, it was confirmed that the granular iron manufacturing apparatus according to the present embodiment can efficiently cool granular iron.

[0075] Next, regarding the water flow control containers 80 and 82 shown in FIGS. 5 and 7, the results of confirming the presence or absence of the intrusion of granular iron into the water supply port 43 will be described. FIG. 14 is a diagram showing the results of confirming the presence or absence of the intrusion of granular iron into the water supply port 43. Invention Example 3 is the water flow control container 80 shown in FIG. 5, and Invention Example 4 is the water flow control container 82 shown in FIG. 7.

[0076] In Invention Example 3, since the protruding portion 90 that covers the upper side of the water supply port 43 was provided, the intrusion of granular iron into the water supply port 43 was suppressed by the protruding portion 90. As a result, it was confirmed that the cooling water 24 can be supplied from the water supply port 43 without being blocked by the granular iron, and the granular iron can be cooled with high cooling efficiency using the water flow control container 80, and granular iron can be manufactured.

[0077] In Invention Example 4, since the protective cover 92 that covers the upper side of the water supply port 43 was provided, the intrusion of granular iron into the water supply port 43 was suppressed by the protective cover 92. As a result, it was confirmed that the cooling water 24 can be supplied from the water supply port 43 without being blocked by the granular iron, and the granular iron can be cooled with high cooling efficiency using the water flow control container 82, and granular iron can be manufactured.

[0078] [Example 2] Next, as Example 2, the results of a simulation for confirming the cooling effect of the granular iron 66 by the conveyor device 50 of the granular iron manufacturing apparatus 70 according to the present embodiment will be described. FIG. 15 is a schematic diagram of the granular iron manufacturing apparatus 70 used in the simulation. FIG. 15(a) is a perspective view of the granular iron manufacturing apparatus 70, and FIG. 15(b) is a schematic side view of the granular iron manufacturing apparatus 70.

[0079] The conditions of the simulation are as follows. Inner diameter of the main cooling water pipe: 200A Length of the main cooling water pipe: 5 m Distance from the main cooling water pipe to the upper surface of the conveyor: 750 mm Inner diameter of the cooling water header pipe: 50A Length of the cooling water header pipe: 1 m Distance from the cooling water header pipe to the granular iron on the conveyor: 250 mm Distance between the cooling water header pipes: 250 mm Number of the cooling water header pipes: 20 Shape of the slit: rectangle (3 mm × 20 mm) Interval between the slits: 10 mm Number of the slits in one cooling water header pipe: 30 Supply speed of the cooling water: 3 m / s Water temperature of the cooling water: 35°C Supply flow rate of the cooling water to the main cooling water pipe 56: 390 m 3 / h (Water supply amount of the cooling water for 5 minutes: 33 m 3 ) Width of the conveyor: 1 m Conveyor speed: 1 m / min Volume of the space sandwiched between the upper surface of the conveyor and the cooling water supply device: 3.6 m 3 Initial water temperature in the cooling water tank: 65°C Surface temperature of the granular iron 66: 700°C

[0080] FIG. 16 is a diagram showing the result of simulating the water temperature in space 59 when cooling water is supplied from the cooling water supply device 54 to space 59. In FIG. 16, cooling water at a water temperature of 35° C. is supplied from a 5 m long cooling water supply device 54 provided above the conveyor 52 to a space 59 sandwiched between the conveyor 52 and the cooling water supply device 54. The granular iron 66 discharged from the discharge port 36 of the water flow control container 30 and stacked on the conveyor 52 is conveyed from the bottom surface of the cooling water tank 20 over 5 minutes at a conveyance speed of 1 m / min. The amount of cooling water supplied from the cooling water header pipe 57 via the main cooling water pipe 56 is 33 m during the 5 minutes when the granular iron 66 is conveyed under the cooling water supply device 54 3 (The supply flow rate of cooling water to the main cooling water pipe 56 is 390 m 3 / h). This is approximately 10 times the volume (3.6 m 3 ) of the space sandwiched between the upper surface of the conveyor 52 and the cooling water supply device 54. By supplying cooling water from the cooling water supply device 54 to the space 59, the water temperature in the space 59 sandwiched between the conveyor 52 and the cooling water supply device 54, whose initial water temperature was 65° C., decreased to 50 to 58° C. Thus, it was confirmed that by using the granular iron manufacturing apparatus 70 according to the present embodiment, the water temperature in the space 59 sandwiched between the conveyor 52 and the cooling water supply device 54 can be maintained in the range of 45° C. to 60° C.

[0081] FIG. 17 is a diagram showing the result of simulating the temperature of the granular iron on the conveyor 52. Assuming that a high-temperature object 66' simulating the granular iron 66 at 700° C. exists on the conveyor 52, the temperature change of the object 66' was simulated. FIG. 17(a) is a side cross-sectional view showing the temperature of the object 66' before cooling, and FIG. 17(b) is a front cross-sectional view showing the temperature of the object 66' before cooling. FIG. 17(c) is a front cross-sectional view showing the temperature of the object 66' 10 seconds after the supply of cooling water.

[0082] As shown in Fig. 17, by supplying cooling water from the slit, the high-temperature object 66’ is cooled, and the surface temperature of the high-temperature object at 700 °C drops to around 400 °C 10 seconds after the supply of cooling water. Thus, by using the pig iron manufacturing apparatus 70 according to this embodiment, it was confirmed that the surface temperature of the pig iron 66 can be cooled from 700 °C to around 400 °C, and it is possible to suppress the pig iron 66 stacked on the conveyor 52 from fusing and coalescing.

Explanation of Signs

[0083] 10 Granulation device 12 Tundish 14 Molten iron receiving pan 16 Nozzle 18 Support 20 Cooling water tank 22 Drain outlet 24 Cooling water 30 Water flow control container 32 Partition cylinder 33 Inlet 34 Inclined surface 35 Duct cylinder 36 Outlet 40 Cooling water pipe group 41 Cooling water pipe 42 Slit 43 Water inlet 44 Upper-stage cooling water pipe group 45 Water supply jacket 46 Middle-stage cooling water pipe group 48 Lower-stage cooling water pipe group 50 Conveying device 52 Conveyor 54 Cooling water supply device 56 Main cooling water pipe 57 Cooling water header pipe 58 Slit 59 Space 60 Molten iron 62 Liquid column 64 Liquid droplet 66 Pig iron 66’ Object 70 Pig iron manufacturing apparatus 80 Water flow control container 82 Water flow control container 90 protrusion 91 protrusion 92 protective cover

Claims

1. A pig iron manufacturing apparatus comprising a granulation device that forms molten iron into droplets, a cooling water tank that cools the droplets by dropping them into cooling water to form granular iron, and a conveying device that conveys the granular iron outside the cooling water tank, comprising a water flow control container provided in the cooling water tank and having openings at both upper and lower ends, and a group of cooling water pipes that supply cooling water into the water flow control container, wherein the water flow control container includes a partition cylinder body having an inclined surface inclined such that the horizontal cross-sectional area becomes narrower downward, and a duct cylinder body connected to the lower part of the partition cylinder body, the group of cooling water pipes includes an upper-stage cooling water pipe group and a middle-stage cooling water pipe group connected to the partition cylinder body, and a lower-stage cooling water pipe group connected to the duct cylinder body, the upper-stage cooling water pipe group is connected to the upper stage of the inclined surface including the upper end of the partition cylinder body, and generates a cooling water flow along the inclined surface from above to below by the cooling water supplied from the upper-stage cooling water pipe group, the middle-stage cooling water pipe group is horizontally connected to the middle stage of the inclined surface of the partition cylinder body toward the cylinder core of the partition cylinder body, and by the cooling water supplied from the middle-stage cooling water pipe group, it flows toward the cylinder core of the partition cylinder body, converges at the cylinder core and rises, generating a first circulation flow that circulates inside the partition cylinder body along with the cooling water flow along the inclined surface from above to below, the lower-stage cooling water pipe group is connected to the side surface of the duct cylinder body, and generates a second circulation flow that circulates inside the duct cylinder body by the cooling water supplied from the lower-stage cooling water pipe group and the drainage water from the partition cylinder body, the conveying device is provided below the water flow control container, and includes a conveyor that conveys the granular iron from inside the cooling water tank to the outside of the cooling water tank, and a cooling water supply device that is provided above the conveyor in the cooling water tank and supplies cooling water for cooling the granular iron carried out by the conveyor. A pig iron manufacturing apparatus.

2. having a control device that controls the amount of cooling water supplied from the group of cooling water pipes to the water flow control container, the control device controls such that the amount of cooling water supplied from the group of cooling water pipes decreases in the order of the middle-stage cooling water pipe group, the upper-stage cooling water pipe group, and the lower-stage cooling water pipe group. The pig iron manufacturing apparatus according to Claim 1.

3. The cooling water supply device supplies the cooling water to a region above the granular iron on the conveyor, and includes a main cooling water pipe provided along the conveying direction of the conveyor, and a plurality of cooling water header pipes respectively connected to the main cooling water pipe side by side in the conveying direction, extending in the width direction of the conveyor, and provided with at least one supply port in the width direction. The granular iron manufacturing apparatus according to claim 1 or claim 2.

4. The granular iron manufacturing apparatus according to claim 1, further comprising a protruding portion covering an upper side of a connection portion where the upper stage cooling water pipe group and / or the middle stage cooling water pipe group is connected to the inclined surface.

5. The granular iron manufacturing apparatus according to claim 4, wherein a cross-sectional shape of the protruding portion is an inverted V shape or an inverted U shape that widens from above downward.

6. The granular iron manufacturing apparatus according to any one of claims 1, 4, and 5, further comprising a protective cover covering an upper side of a connection portion where the upper stage cooling water pipe group is connected to the inclined surface, and an upper end portion of the protective cover is closed.

7. The granular iron manufacturing apparatus according to claim 6, wherein a cross-sectional shape of the protective cover is a semi-circular or semi-elliptical shape that widens from above downward.

8. The granular iron manufacturing apparatus according to claim 3, wherein the supply port is a rectangular slit having a short side length of 3 mm or more.

Images