Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D25/00—Special casting characterised by the nature of the product
  • B22D25/02—Special casting characterised by the nature of the product by its peculiarity of shape; of works of art
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
  • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying

Definitions

• the present invention relates to a granulated iron manufacturing device that produces granulated iron from molten iron.
• Nuggets are molten iron such as molten iron or steel that has been dispersed and then solidified into granules, with an average particle size of several mm to several tens of mm.
• molten iron such as molten iron or steel that has been dispersed and then solidified into granules, with an average particle size of several mm to several tens of mm.
• this is temporarily stored as granules.
• blast furnaces have become larger, and if a large amount of molten iron cannot be temporarily processed, it will lead to a reduction in the wind in the blast furnace. For this reason, there is a demand for buffer equipment in case a problem occurs in the process below steelmaking.
• Patent Document 1 discloses a method of granulating molten iron by spraying pressurized water onto the molten iron.
• the method disclosed in Patent Document 1 often results in hollow granules, which can accumulate water in the hollows and cause steam explosions when remelted.
• Patent Document 2 discloses a granular metal manufacturing method in which molten iron is dropped onto a fixed plate, and the droplets bounce off the plate and fall into a cooling bath below where they are cooled, thereby producing granular iron.
• the granular iron cooled in a cooling water tank is collected by a cylindrical flat plate structure and a pipe connected to the tapered lower half of the cylinder, and is piled up on a conveyor, which is a transport device.
• Patent Document 3 discloses an apparatus that granulates molten iron with a water flow, and cools and solidifies the liquid granular iron by dropping it into water, thereby producing a large amount of granular iron.
• the iron pellets are very hot when they are dropped into the water.
• the temperature of the iron pellets is around 1200-1500°C, so when such hot iron pellets come into contact with water, a film boiling state occurs in which a steam film forms on the surface of the hot object, causing the water to evaporate and remove the heat from the iron pellets.
• This film boiling has a low cooling capacity, for example, its heat transfer coefficient is only about 1/100th of that of nucleate boiling, in which no steam film forms. For this reason, if film boiling continues for a long time, the iron pellets will not be cooled sufficiently, and they may fuse together and merge in the cooling water.
• Patent Document 3 describes how the amount of secondary cooling water can be adjusted to maintain the cooling water temperature in the pit at 68°C or below, thereby preventing the iron granules that have accumulated in the pit from coalescing.
• the cooling water tank is equipped with an outlet for supplying cooling water and a drain for transporting the heated cooling water to the cooling equipment, allowing the cooling water to circulate between the cooling water tank and the cooling equipment.
• Patent Document 3 describes adjusting the amount of secondary cooling water to maintain the cooling water temperature in the pit at 68°C or less, but does not describe any method for controlling the flow in the cooling water tank, and depending on the flow of cooling water, stagnant areas may occur in the cooling water tank. Warm cooling water used to cool the iron granules may remain in this stagnant area, creating a local area with high water temperature. If a large amount of iron granules is poured into this area of high water temperature, a film boiling state is maintained for a long time, and the iron granules are not cooled sufficiently, causing them to fuse together and merge. When the iron granules merge, the number of iron granules that are difficult to transport increases, making transportation difficult. There is a problem that if cooling water is included when the iron granules combine, it can cause a steam explosion.
• Patent Document 2 even if the surface of the iron granules has cooled and solidified by the time they are collected on the conveyor, the inside of the iron granules remains in an unsolidified, high-temperature state. Furthermore, because the iron granules are stacked in a dense state on the conveyor, when the amount of heat removed from the surface of the iron granules by the cooling water decreases, the amount of heat transferred from the inside of the iron granules to the surface exceeds the amount of heat removed from the surface of the iron granules by the cooling water, causing recuperation, which causes the surface temperature of the iron granules to rise. This creates the problem that the surface temperature of the iron granules rises again as they recuperate while being transported on the conveyor, and the stacked iron granules easily fuse and combine to form large lumps.
• the present invention was made to solve these problems, and its purpose is to provide a granular iron manufacturing device that can efficiently cool molten iron and also efficiently cool granular iron being transported by a transport device such as a conveyor, thereby preventing the granular iron from combining with each other.
• An apparatus for manufacturing granulated iron comprising: a granulation device for turning molten iron into droplets; a cooling water tank for dropping the droplets into cooling water to cool them into granulated iron; and a transport device for transporting the granulated iron to the outside of the cooling water tank, the apparatus comprising: a water flow control vessel provided within the cooling water tank and having upper and lower ends open; and a cooling water pipe group for supplying cooling water into the water flow control vessel, the water flow control vessel having a partition cylinder having an inclined surface inclined so that the horizontal cross-sectional area narrows downward; and a duct cylinder connected to the lower part of the partition cylinder, the cooling water pipe group comprising an upper stage cooling water pipe group and a middle stage cooling water pipe group connected to the partition cylinder, and a lower stage cooling water pipe group connected to the duct cylinder, the upper stage cooling water pipe group being connected to an upper part of the inclined surface including the upper end of the partition cylinder, a
• a first circulating flow of cooling water from bottom to top is generated within the partition cylinder, and a second circulating flow of cooling water from bottom to top is generated within the duct cylinder, and the granular iron is cooled by this circulating flow.
• This increases the cooling efficiency of the granular iron within the partition cylinder and duct cylinder, and prevents the granular iron from fusing and combining with each other when cooling.
• cooling of the granular iron is performed by supplying cooling water above the granular iron being conveyed.
• the granulated iron manufacturing device of the present invention can produce granulated iron by increasing the cooling efficiency of the granulated iron, which reduces the amount of cooling water used. Furthermore, because the cooling efficiency of the granulated iron is high, if the cooling capacity of the granulated iron manufacturing device is the same, the device becomes more compact, which prevents the equipment from becoming too large, and if the size of the manufacturing device is the same, it becomes a device that can produce more granulated iron.
• FIG. 1 is a schematic cross-sectional view of an apparatus for manufacturing granular iron according to the present embodiment.
• FIG. 2 is a schematic cross-sectional view of the water flow control vessel at a portion where the cooling water pipe group is connected.
• FIG. 3 is a schematic cross-sectional view illustrating a circulating flow occurring within the partition cylinder and the duct cylinder.
• FIG. 4 is a schematic diagram showing a part of the conveying device.
• FIG. 5 is a schematic cross-sectional view showing another water flow control vessel used in the granular iron manufacturing apparatus according to this embodiment.
• FIG. 6 is a schematic diagram of a water supply port provided with a protrusion, as viewed from the horizontal direction.
• FIG. 1 is a schematic cross-sectional view of an apparatus for manufacturing granular iron according to the present embodiment.
• FIG. 2 is a schematic cross-sectional view of the water flow control vessel at a portion where the cooling water pipe group is connected.
• FIG. 3 is a schematic cross-section
• FIG. 7 is a schematic cross-sectional view showing another water flow control vessel used in the granular iron manufacturing apparatus according to this embodiment.
• FIG. 8 is a schematic diagram of a water supply port provided with a protective cover, as viewed from the horizontal direction.
• FIG. 9 is a diagram showing simulation conditions for invention examples 1 and 2.
• FIG. 10 is a diagram showing simulation conditions for Comparative Example 1 and Comparative Example 2.
• FIG. 11 is a diagram showing the simulation results of the invention examples 1 and 2.
• FIG. 12 is a schematic perspective view showing the flow of cooling water supplied from each cooling water pipe group in the first example.
• FIG. 13 is a diagram showing the simulation results of Comparative Example 1 and Comparative Example 2.
• FIG. 14 is a diagram showing the results of checking whether or not granular iron has entered the water supply port.
• FIG. 14 is a diagram showing the results of checking whether or not granular iron has entered the water supply port.
• FIG. 15 is a schematic diagram of a granulated iron manufacturing apparatus used in the simulation.
• FIG. 16 is a diagram showing the results of simulating the water temperature in a space when cooling water is supplied from a cooling water supply device to the space.
• FIG. 17 is a diagram showing the results of simulating the temperature of iron granules on a conveyor.
• FIG. 1 is a schematic cross-sectional view of a granular iron manufacturing apparatus 70 according to this embodiment.
• the granular iron manufacturing apparatus 70 is an apparatus that produces granular iron, which is a granular iron material, by cooling and solidifying molten iron such as molten iron or molten steel in a liquid state.
• the granular iron manufacturing apparatus 70 has a granulation device 10 that converts the molten iron into droplets, a cooling water tank 20, a water flow control vessel 30, a group of cooling water pipes 40, and a transport device 50.
• the granulation device 10 has a tundish 12 (such as a molten iron bucket) that contains molten iron 60 and has a nozzle 16 at the bottom for discharging the molten iron, and a molten iron receiving plate 14 against which the liquid column 62 of molten iron discharged from the nozzle 16 and flowing down collides.
• the molten iron receiving plate 14 is made of a disk-shaped refractory material and is supported by a support 18.
• the liquid column 62 of molten iron flowing down from the nozzle 16 collides with the molten iron receiving plate 14, causing droplets 64 of molten iron 60 to scatter around it.
• the granulation device 10 it is preferable for the granulation device 10 to turn the molten iron 60 into droplets 64 such that the maximum length of the granulated iron 66 after cooling is 50 mm or less.
• the molten iron 60 is turned into droplets 64 by the granulation device 10 and falls into the cooling water 24. Furthermore, 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 area where the water flow control vessel 30 is provided.
• the cooling water tank 20 contains cooling water 24 and a water flow control vessel 30.
• the water flow control vessel 30 is placed in the cooling water 24 contained in the cooling water tank 20.
• the cooling water 24 contained in the cooling water tank 20 may include cooling water 24 drained from the water flow control vessel 30.
• the cooling water 24 contained in the cooling water tank 20 is drained from the drain outlet 22 in an amount equal to the amount of cooling water supplied so that the cooling water level in the cooling water tank 20 remains constant.
• the water flow control vessel 30 is disposed within the cooling water tank 20 at a position that receives the molten iron 60 that has been turned into droplets 64 by the granulation device 10.
• the water flow control vessel 30 cools and solidifies the droplets 64 with the cooling water 24 contained therein to turn them into granulated iron 66.
• the water flow control vessel 30 has a partition cylinder 32 with an inclined surface 34 that is inclined so that the horizontal cross-sectional area narrows downward, and a duct cylinder 35 connected to the lower side of the partition cylinder 32.
• the upper end of the partition cylinder 32 is provided with an inlet 33 for receiving droplets 64, and the lower end of the duct cylinder 35 is provided with an outlet 36 for discharging the iron nuggets 66.
• the water flow control vessel 30 has open upper and lower ends.
• the inclined surface 34 may be formed on the inside of the water flow control vessel 30, and the shape of the outside of the water flow control vessel 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 degrees from the viewpoint of not allowing the iron nuggets 66 to remain.
• the partition cylinder 32 does not have a cylindrical portion on the upper end side, but the partition cylinder 32 may have a cylindrical portion on the upper end side.
• the cooling water pipe group 40 is a water pipe group 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 cooling tower (not shown) passes.
• cooling equipment such as a heat exchanger or cooling tower (not shown)
• the cooling water 24 tends to flow upward where the opening is larger. Therefore, when the cooling water is supplied from the bottom of the partition cylinder 32 toward the cylinder core, the cooling water 24 joins at the cylinder core inside the partition cylinder 32 and rises.
• the cooling water pipe group 40 has an upper stage cooling water pipe group 44 and a middle stage cooling water pipe group 46 that are connected to the partition cylinder, and a lower stage cooling water pipe group 48 that is connected to the duct cylinder 35.
• the middle stage cooling water pipe group 46 is connected horizontally toward the cylinder core of the partition cylinder 32 to the middle stage of the inclined surface 34 in the range from the center of the partition cylinder 32 in the vertical direction to 650 mm below.
• the cooling water 24 flows toward the cylinder core of the partition cylinder 32, joins at the cylinder core, and rises.
• the cooling water 24 that joins at the cylinder core and rises spreads in the circumferential direction at the upper end of the partition cylinder 32 and flows downward along the inclined surface 34, forming a first circulating flow.
• the cooling water 24 supplied from the middle stage cooling water pipe group 46 forms part of the first circulating flow.
• the amount of cooling water supplied from the middle stage cooling water pipe group 46 is preferably 1500 m3 /h or more and 3900 m3 /h or less. If the amount of cooling water is less than 1500 m3 /h, it is not preferable because it is difficult to generate a strong and stable upward flow at the cylinder core of the partition cylinder 32. If the amount of cooling water is more than 3900 m3 /h, it is not preferable because it causes cooling water 24 to deviate from the first circulating flow and flow out from the inlet 33 of the partition cylinder 32 into the cooling water tank 20.
• 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 cylindrical core of the partition cylinder 32, making it difficult to generate a strong and stable upward flow, which is not preferable. 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 will be required, which is not preferable.
• the upper cooling water pipe group 44 is connected to the upper part of the inclined surface 34 including the upper end of the partition cylinder 32.
• the upper cooling water pipe group 44 covers the upper part of the partition cylinder 32 including the slit 42 having a predetermined gap around the periphery of the upper end of the partition cylinder 32 and the water supply port 43 on the upper inclined surface 34 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 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 down to 1000 mm.
• the flow velocity of the cooling water 24 supplied from the slits 42 and the water supply port 43 is preferably 0.1 m/s or more and 0.7 m/s or less.
• the amount of cooling water supplied from the upper cooling water pipe group 44 is preferably 700 m 3 /h or more and 3000 m 3 /h or less.
• the amount of cooling water supplied from the upper cooling water pipe group 44 is less than 700 m 3 /h, it is not preferable because there is a risk that the first circulating flow cannot be stabilized. If the amount of cooling water supplied from the upper cooling water pipe group 44 is more than 3000 m3 /h, the effect of stabilizing the first circulating flow is saturated, and the water does not contribute to cooling the granulated iron 66, but simply flows down along the inclined surface 34 and is drained from the drain port 22 at the lower end of the partition cylinder 32, which is not preferable.
• the ratio of the amount of cooling water supplied from the slits 42 and the water supply port 43 is preferably 6:4.
• the lower cooling water pipe group 48 has at least one set of water pipes connected horizontally to the side of the duct cylinder 35, facing each other toward the cylinder core of the duct cylinder 35.
• the amount of cooling water supplied from the lower cooling water pipe group 48 is preferably 250 m3 /h or more and 750 m3 /h or less. If the amount of cooling water supplied from the lower cooling water pipe group 48 is less than 250 m3 /h, it is not preferable because the second circulating flow is difficult to generate in the duct cylinder 35 and there is a risk of a stagnation region with a high water temperature being generated. If the amount of cooling water supplied from the lower cooling water pipe group 48 is more than 750 m3 /h, it is not preferable because it impedes drainage from the lower end of the partition cylinder 32.
• the flow velocity 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 velocity of the cooling water 24 supplied into the duct cylinder 35 is slower than 0.5 m/s, the effect of stirring inside the duct cylinder 35 will be reduced, which is not preferable. If the flow velocity of the cooling water 24 supplied into the duct cylinder 35 is faster than 1.0 m/s, leakage from the gap between the lower end of the duct cylinder 35 and the conveying device 50 will increase, which is not preferable.
• Figure 2 is a schematic cross-sectional view of the water flow control vessel 30 where the cooling water pipe group is connected.
• Figure 2(a) is a schematic cross-sectional view of the water flow control vessel 30 where the upper cooling water pipe group 44 is connected
• Figure 2(b) is a schematic cross-sectional view of the water flow control vessel 30 where the middle cooling water pipe group 46 is connected
• Figure 2(c) is a schematic cross-sectional view of the water flow control vessel 30 where the lower cooling water pipe group 48 is connected.
• 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 a water supply jacket 45, where it is distributed to an annular slit 42 and 16 water supply ports 43 arranged radially on the inclined surface 34 of the partition cylinder 32.
• the cooling water 24 is supplied into the partition cylinder 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 arranged horizontally toward the cylinder core of the partition cylinder 32.
• the cooling water 24 is supplied into the partition cylinder 32 from the four cooling water pipes 41.
• the lower cooling water pipe group 48 is composed of four cooling water pipes 41.
• cooling water pipes 41 are arranged horizontally facing each other toward the cylindrical core of the duct cylinder 35, and the other two cooling water pipes 41 are arranged on the side of the duct cylinder.
• the cooling water 24 is supplied into the duct cylinder 35 from the four cooling water pipes 41.
• cooling water is supplied into the partition cylinder 32 and the duct cylinder 35 by a total of ten cooling water pipes 41.
• the cross-sectional shape of the duct cylinder 35 is rectangular, but this is not limiting, and the cross-sectional shape of the duct cylinder 35 may be circular.
• the first circulating flow B1 is a circulating flow that circulates in the partition cylinder 32.
• the cooling water 24 supplied from the middle stage cooling water pipe group 46 joins at the cylinder core to form a strong upward flow. This strong upward flow spreads to the periphery near the inlet 33.
• the water flow that spreads to the periphery becomes a downward flow that descends along the inclined surface 34.
• the downward flow joins with the cooling water flow from the slit 42 and the water supply port 43, and due to the straightening action of these cooling water flows, flows downward along the inclined surface 34 and is discharged from the lower end connected to the duct cylinder 35.
• the first circulating flow B1 in the partition cylinder 32 allows the water temperature in the area from the middle stage to the upper stage in the cooling area A to be maintained at an appropriate water temperature of around 50°C.
• the strong upward flow generated in the core of the partition cylinder 32 flows counter to the downward flow of the nuggets of iron 66 that are fed through the feed port 33, allowing the nuggets of iron 66 to be cooled with high cooling efficiency.
• the second circulating flow B2 is a circulating flow that occurs within the duct cylinder 35.
• the discharged water from the lower end of the partition cylinder 32 merges with the discharged water of low water temperature from the lower cooling water pipe group 48 and is stirred, thereby generating a circulating flow within the duct cylinder 35. This allows the granular iron collected by the partition cylinder 32 to be cooled efficiently.
• the upward flow generated in the core of the partition cylinder 32 becomes a cooling water flow that faces the falling iron nuggets 66 that are fed from the feed port 33, resulting in high cooling efficiency.
• the total amount of cooling water supplied from the middle-stage cooling water pipe group 46 be greater than the total amount of cooling water supplied from the upper-stage cooling water pipe group 44.
• the total amount of cooling water supplied from the lower cooling water pipe group 48 connected to the duct cylinder 35 is preferably smaller than the total amount of cooling water supplied from the upper cooling water pipe group 44. If the total amount of cooling water supplied from the lower cooling water pipe group 48 is greater than the total amount of cooling water supplied from the upper cooling water pipe group 44, the drainage from the lower end of the partition cylinder 32 to the duct cylinder 35 is hindered, which may raise the concern that the temperature inside the partition cylinder 32 may increase. Therefore, it is preferable that the total amount of cooling water supplied from the lower cooling water pipe group 48 is smaller than the total amount of cooling water supplied from the upper cooling water pipe group 44. Furthermore, it is more preferable that the total amount of cooling water supplied from the lower cooling water pipe group 48 is about 1/2 of the total amount of cooling water supplied from the upper cooling water pipe group 44.
• the granular iron manufacturing device 70 In order to favorably generate the first circulating flow B1 and prevent the temperature inside the partition cylinder 32 from rising, it is preferable to decrease the total amount of cooling water supplied from each cooling water pipe group in the order of the middle cooling water pipe group 46, the upper cooling water pipe group 44, and the lower cooling water pipe group 48. In this way, it is preferable to control the total amount of cooling water supplied from each cooling water pipe group as described above. For this reason, it is preferable that the granular iron manufacturing device 70 according to this embodiment further has a control device that controls the total amount of cooling water supplied from the upper cooling water pipe group 44, the middle cooling water pipe group 46, and the lower cooling water pipe group 48.
• the control device is composed of a general-purpose computer, and controls cooling equipment such as a heat exchanger and a cooling tower (not shown) to control the amount of cooling water 24 supplied to each cooling water pipe group.
• the granular iron 66 cooled in the water flow control vessel 30 is discharged from the outlet 36 provided at the bottom of the water flow control vessel 30.
• the discharged granular iron 66 is transported outside the cooling water tank 20 by the transport device 50.
• Figure 4 is a schematic diagram showing a part of the transport device 50.
• Figure 4(a) is a schematic side cross-sectional view showing a part of the transport device 50.
• Figure 4(b) is a schematic top view showing the water flow control vessel 30 and a part of the transport device 50.
• the transport device 50 transports the granular iron 66 discharged from the discharge outlet 36 out of the cooling water tank 20.
• the transport device 50 includes a conveyor 52 that transports the granular iron 66 out of the cooling water tank 20, and a cooling water supply device 54 provided above the conveyor 52.
• the granulated iron 66 discharged from the discharge port 36 is stacked on the conveyor 52.
• the conveyor 52 transports the stacked granulated iron 66 out of the cooling water tank 20. It is preferable that the conveyor 52 be a mesh conveyor so that the cooling water is not transported out of the cooling water tank 20 along with the transport of the granulated iron 66.
• the cooling water supply device 54 includes a main cooling water pipe 56 and multiple cooling water header pipes 57 arranged along the conveying direction of the conveyor 52.
• the main cooling water pipe 56 is a water pipe that supplies cooling water cooled by cooling equipment such as a heat exchanger or a cooling tower to the cooling water header pipe 57.
• the cooling water header pipe 57 is a water pipe that extends in the width direction of the conveyor 52.
• the cooling water header pipe 57 has multiple rectangular slits 58 in the width direction, and cooling water is supplied from the slits 58.
• the rectangular slits 58 are an example of a supply port.
• the supply port may be a rectangular slit of the same length as the longitudinal length of the cooling water header pipe 57 extending in the width direction, or may be multiple circular pipe nozzles arranged in the longitudinal direction. In other words, it is sufficient that at least one supply port is provided in the width direction of the conveyor 52.
• the rectangular slit 58 is preferably sized to prevent clogging due to sludge mixed into the cooling water. Since the size of the sludge mixed into the cooling water is about 1 to 2 mm, it is preferable that the length of the short side of the slit 58 is 3 mm or more. The length of the long side of the slit 58 can be set to a length that ensures a cooling water supply speed of 2 to 3 m/sec.
• the cooling water header pipes 57 are arranged in a line in the conveying direction of the conveyor 52, and each is connected to the cooling water main pipe 56.
• the space 59 to which cooling water is supplied from the slits 58 of the cooling water header pipe 57 is above the granular iron 66 on the conveyor 52, and is an area sandwiched between the conveyor 52 and the cooling water supply device 54. In this area, the cooling water that has become hot by cooling the granular iron 66 discharged from the water flow control vessel 30 is retained. For this reason, the cooling water supply device 54 is used to supply cooling water to the space 59, which generates a convection of the cooling water in the space 59 and removes the hot cooling water from the space 59.
• the granulated iron 66 collected on the conveyor 52 can be cooled by supplying cooling water to a limited area above the conveyor 52, so there is no need to circulate the cooling water throughout the entire cooling water tank 20, and the granulated iron 66 can be cooled efficiently with a small amount of cooling water.
• the surface temperature of the granular iron 66 discharged from the outlet 36 is around 800°C, so the surface of the granular iron 66 is covered with a steam film. If low-temperature cooling water is directly sprayed onto the granular iron 66, the steam film breaks and the low-temperature cooling water comes into direct contact with the surface of the granular iron 66, which may cause a steam explosion, which is an explosive boiling. For this reason, in order to stably cool the granular iron 66, it is preferable not to spray low-temperature cooling water directly onto the granular iron 66, but 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°C to 60°C.
• the water temperature exceeds 65°C, the water is more likely to boil, so a steam film is more likely to be maintained around the high-temperature object, which makes film boiling more likely, and the cooling ability of the granular iron is significantly reduced. If the temperature falls below 40°C, the steam film covering the surface of the granular iron 66 becomes unstable, which is not preferable as there is a concern that a steam explosion may occur.
• the cooling water supply device 54 has a plurality of cooling water header pipes 57 with a plurality of slits 58 formed in the width direction of the conveyor 52, spaced apart in the conveying direction of the conveyor 52. In this way, cooling water is supplied to the space 59 from the numerous slits 58 of the cooling water header pipes 57 formed along the conveying direction of the conveyor 52. This reduces the amount of cooling water supplied from each slit 58, preventing the cooling water from being sprayed directly onto the granulated iron 66, while generating a convection current of the cooling water in the space 59.
• the supply speed of the cooling water supplied from the rectangular slits 58 is preferably within the range of 2 m/sec to 3 m/sec.
• the supply speed of the cooling water is preferably within the range of 2 m/sec to 3 m/sec.
• the amount of cooling water supplied from the cooling water header pipe 57 should be at least 10 times the volume of the space 59 during the time it takes for the granular iron 66 to be transported by the transport device 50 and removed from the cooling water tank 20. This amount of cooling water to be supplied can be determined from the results of a simulation, which will be described later.
• the distance between the cooling water header pipes 57 is approximately the same length as the distance between the cooling water header pipes 57 and the granulated iron 66 transported on the conveyor 52. This prevents the cooling water from stagnating between the cooling water header pipes 57, and allows the cooling water temperature in the space 59 to be evenly lowered. It is preferable that the temperature of the cooling water supplied from the cooling water header pipes 57 is within the range of 30°C to 45°C. If the temperature of the cooling water supplied from the cooling water header pipes 57 falls below 30°C and the supplied cooling water comes into direct contact with the surface of the granulated iron 66, this is not preferable because there is a risk of a steam explosion, which is an explosive boiling phenomenon. If the temperature of the cooling water exceeds 45°C, the cooling effect of the granulated iron 66 decreases, which is not preferable.
• FIG. 5 is a schematic cross-sectional view showing another water flow control vessel 80 used in the granular iron manufacturing apparatus according to this embodiment.
• the same components as those in the water flow control vessel 30 shown in FIG. 1 are given the same reference numbers, and their description will be omitted.
• the water flow control vessel 80 shown in FIG. 5 differs from the water flow control vessel 30 shown in FIG. 1 in that it has a protrusion 90.
• a water inlet 43 for supplying cooling water 24 is provided on the inclined surface 34 of the partition cylinder 32, there is a concern that the iron pellets 66 falling along the inclined surface 34 may enter the water inlet 43 and block it.
• covering the upper side of the connection between the water inlet 43 and the middle-stage cooling water pipe group 46 means that the protrusion 90 is provided to a position where the connection between the water inlet 43 and the middle-stage cooling water pipe group 46 is hidden when viewed from above.
• the protrusion 90 is provided so as to protrude horizontally from the inclined surface 34 toward the inside of the partition cylinder 32 so as not to impede the flow of the cooling water 24 being supplied.
• Figure 6 is a schematic diagram of the water supply port 43 with a protrusion, viewed from the horizontal direction.
• Figure 6(a) shows an inverted V-shaped protrusion 90
• Figure 6(b) shows an inverted U-shaped protrusion 91.
• the cross-sectional shape of the protrusion 90 is preferably an inverted V-shape that protrudes upward and slopes downward.
• a protrusion 91 having an inverted U-shaped cross section may be provided instead of the protrusion 90.
• the protrusion 91 having an inverted U-shaped cross section in this manner, it is possible to prevent the accumulation of the granular iron 66 on the upper surface of the protrusion 91 while also preventing the granular iron 66 from entering the water supply port 43.
• FIG. 7 is a schematic cross-sectional view showing another water flow control vessel 82 used in the granular iron manufacturing apparatus according to this embodiment.
• the same components as those in the water flow control vessel 80 shown in FIG. 5 are given the same reference numbers, and their description will be omitted.
• the water flow control vessel 82 shown in FIG. 7 differs from the water flow control vessel 80 shown in FIG. 5 in that it has a protective cover 92.
• the granular iron 66 falling along the inclined surface 34 may enter the water supply port 43 and block the water supply port 43.
• the granular iron 66 in the upper part of the partition cylinder 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.
• covering the upper side of the water supply port 43 means providing the protective cover 92 up to a position where the water supply port 43 is hidden when viewed from above.
• the protective cover 92 is provided at a position where the water supply port 43 is not hidden when the water supply port 43 is viewed horizontally 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. It is preferable that the upper end of the protective cover 92 has a closed structure so that scattered droplets 64 do not enter the protective cover 92, and it is preferable that the inclination angle of the protective cover 92 is the same as that of the inclined surface 34.
• Figure 8 is a schematic diagram of the water supply port 43 provided with a protective cover 92, viewed from the horizontal direction.
• the cross-sectional shape of the protective cover 92 is preferably a semicircular or semi-elliptical shape that widens downward.
• a protrusion 90 or a protective cover 92 is provided for the water supply port 43, but this is not limiting, and a protrusion 90 and a protective cover 92 may be provided for the water supply port 43. Even with this configuration, it is possible to prevent the entry of granular iron 66 into the water supply port 43.
• a first circulating flow B1 of cooling water 24 flowing from bottom to top inside the partition cylinder 32 is generated, and a second circulating flow B2 of cooling water 24 flowing from bottom to top inside the duct cylinder 35 is generated.
• the granular iron 66 is cooled by these two circulating flows to manufacture the granular iron 66 from the molten iron 60. Since the first circulating flow B1 is a counterflow to the descending direction of the granular iron 66, the granular iron 66 can be efficiently cooled by the first circulating flow B1.
• the granular iron manufacturing apparatus 70 has a conveying device 50 equipped with a cooling water supply device 54, so that the granular iron 66 can be efficiently cooled by replacing the cooling water in a limited area on the conveying device 50 where the granular iron 66 is collected.
• a cooling water supply device 54 By cooling the granular iron 66 in this manner, it is possible to prevent the granular iron 66 being fused together and combined with each other as they are conveyed by the conveyor 52.
• the cooling efficiency of the granular iron 66 by the cooling water is improved, so that the amount of cooling water used can be reduced and the size of the equipment can be prevented from increasing.
• Example 1 Next, the results of a simulation confirming the effect of cooling granulated iron by the granulated iron manufacturing apparatus according to this embodiment will be described as Example 1.
• a cooling water supply model with the same configuration as the water flow control vessel 30 placed in the cooling water tank 20 shown in Fig. 1 was created, and the model was used to simulate the temperature distribution of the cooling water in and around the water flow control vessel.
• the falling speed and heat quantity of the granulated iron in the water in the partition cylinder and on the inclined surface were actually measured in an experiment carried out in advance, and the positional distribution and heat quantity of the granulated iron in the partition cylinder and duct cylinder were modeled.
• the simulation results showed that if the temperature of the cooling water inside the partition cylinder, duct cylinder and surrounding area was below 70°C, and if the temperature of the granular iron was cooled to below 650°C when the granular iron was piled up on the conveying device, then the granular iron was judged to be cooled effectively.
• FIG. 9 is a diagram showing the simulation conditions for Example 1 and Example 2.
• FIG. 10 is a diagram showing the simulation conditions for Comparative Example 1 and Comparative Example 2. Simulations were performed by setting the cooling water supply models for Example 1, Example 2, Comparative Example 1, and Comparative Example 2 to the piping layout, number of pipes, cooling water flow rate distribution, and pipe diameter (nominal diameter (A)) shown in FIG. 9 and FIG. 10.
• the cooling water pipe layout for Example 1 is the same as the cooling water pipe layout for the water flow control vessel 30 shown in FIG. 2.
• Example 2 The cooling water pipe layout of Example 2 is the same as that of Example 1, except that there is one cooling water pipe connected to the water supply jacket of the upper cooling water pipe group, and one less water pipe connected to the side of the duct cylinder of the lower cooling water pipe group than in Example 1.
• the total amount of cooling water supplied from the middle cooling water pipe group is about 40% of that in Example 1
• the amount of cooling water supplied from the upper cooling water pipe group is three times that of Example 1
• the total amount of cooling water supplied from the cooling water pipe group is the same as that of Example 1, making it a model in which the cooling water flow rate distribution has been changed.
• Comparative Example 1 the upper and lower cooling water pipe groups were eliminated, and cooling water was supplied only by the middle cooling water pipe group.
• the number of pipes in the middle and lower cooling water pipe groups was reduced to less than half that of Example 1, the amount of cooling water supplied was halved, and the amount of cooling water supplied from the upper cooling water pipe group was double that of Example 1, resulting in a model with a different cooling water flow rate distribution.
• the two pipes of the middle 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 each cooling water pipe were parallel.
• Example 1 Temperature of molten iron: 1500°C
• Flow rate of molten iron from tundish: 450 tons/h (3) Cooling water temperature: 35°C (4) Angle of inclination of the inclined surface of the partition cylinder: 56° (5)
• Figure 11 shows the simulation results for Example 1 and Example 2.
• the cooling water temperature in the water flow control vessel was 52-69°C, achieving the target of 70°C or less.
• the temperature of the granular iron when it piled up on the conveying device was a maximum of 550°C, achieving the target granular iron temperature of 650°C or less.
• FIG. 12 is a schematic perspective view showing the flow of cooling water supplied from each cooling water pipe group in Example 1.
• FIG. 12(a) is a schematic perspective view showing the flow of cooling water supplied from the upper cooling water pipe group.
• FIG. 12(b) is a schematic perspective view showing the flow of cooling water supplied from the middle cooling water pipe group.
• FIG. 12(c) is a schematic perspective view showing the flow of cooling water supplied from the lower cooling water pipe group.
• Example 2 although the amount of cooling water from the middle cooling water pipe group was reduced to 40%, an upward flow occurred at the cylinder core. A strong water flow descending from the upper cooling water pipe group along the inclined surface of the partition cylinder was generated, especially on the side where the cooling water pipe was connected to the water supply jacket (the right side of the paper). This stabilized the first circulation flow and stirred the cooling water, and the cooling water temperature in the water flow control vessel was maintained below 70°C, achieving the target of below 70°C. Furthermore, the temperature when the granular iron was piled up on the conveying device was a maximum of 646°C, and the target granular iron temperature of below 650°C was also achieved.
• Example 1 Comparing the temperature when the granular iron was piled up on the conveying device in Example 1 and Example 2, Example 1, in which the total amount of cooling water supplied from the middle cooling water pipe group was greater than the total amount of cooling water supplied from the upper cooling water pipe group, was about 100°C lower. From these results, it was confirmed that by making the total amount of cooling water supplied from the middle-stage cooling water tube group greater than the total amount of cooling water supplied from the upper-stage cooling water tube group, it is possible to cool the nugget iron with high cooling efficiency.
• Figure 13 shows the simulation results for Comparative Example 1 and Comparative Example 2.
• Comparative Example 1 a large amount of cooling water was supplied from the middle-stage cooling water pipe group, which created a strong upward flow. The upward flow stirred the cooling water, and the cooling water temperature in the center of the partition cylinder was maintained at 70°C or less. However, the cooling water was not stirred at the upper and lower parts of the partition cylinder, and stagnation occurred in the cooling water in those areas. As a result, the temperature of the granular iron when it was piled up on the conveying device was 652°C, slightly exceeding the target of 650°C or less.
• Comparative Example 2 the two pipes of the middle cooling water pipe group were connected to the partition cylinder on the 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 cooling water pipes were parallel to each other. Therefore, unlike Example 1 of the invention and Comparative Example 1, a strong upward flow was not generated near the cylinder core, and instead of the upward flow, a swirling flow was generated that swirled and rose inside the partition cylinder.
• the water temperature inside the partition cylinder of Comparative Example 2 was lower than that of Example 1 of the invention and Comparative Example 1.
• FIG. 14 is a diagram showing the results of checking whether or not granular iron has entered the water supply port 43.
• Example 3 of the invention is the water flow control vessel 80 shown in Figure 5
• Example 4 of the invention is the water flow control vessel 82 shown in Figure 7.
• Example 3 a protrusion 90 was provided to cover the upper side of the water supply port 43, which prevented the intrusion of granular iron into the water supply port 43. This allowed the cooling water 24 to be supplied from the water supply port 43 without being blocked by the granular iron, and it was confirmed that the granular iron could be cooled with high cooling efficiency using the water flow control vessel 80 to produce granular iron.
• Example 4 a protective cover 92 was provided to cover the top of the water supply port 43, which prevented the intrusion of granular iron into the water supply port 43. This allowed the cooling water 24 to be supplied from the water supply port 43 without being blocked by the granular iron, and it was confirmed that the granular iron could be cooled with high cooling efficiency using the water flow control vessel 82 to produce granular iron.
• Example 2 Next, as Example 2, the results of a simulation confirming the cooling effect of granulated iron 66 by the conveying device 50 of the granulated iron manufacturing apparatus 70 according to this embodiment will be described.
• Fig. 15 is a schematic diagram of the granulated iron manufacturing apparatus 70 used in the simulation.
• Fig. 15(a) is a perspective view of the granulated iron manufacturing apparatus 70
• Fig. 15(b) is a schematic side view of the granulated iron manufacturing apparatus 70.
• the simulation conditions are as follows. Inner diameter of cooling water main pipe: 200A Length of cooling water main pipe: 5m Distance between main cooling water pipe and top of conveyor: 750 mm Inner diameter of cooling water header pipe: 50A Cooling water header pipe length: 1m Distance between the cooling water header pipe and the granulated iron on the conveyor: 250 mm Distance between cooling water header pipes: 250 mm Number of cooling water header pipes: 20 Slit shape: Rectangular (3mm x 20mm) Distance between slits: 10 mm Number of slits in one cooling water header pipe: 30 Cooling water supply speed: 3 m/s Cooling water temperature: 35°C Flow rate of cooling water supplied to the cooling water main pipe 56: 390 m 3 /h (Cooling water supply volume per 5 min: 33 m3 ) Conveyor width: 1m Conveyor speed: 1 m/min Volume of the space between the top surface of the conveyor and the cooling water supply device: 3.6 m3 Initial water temperature in the cooling tank: 65°C Surface temperature of
• the amount of cooling water supplied from the cooling water header pipe 57 via the cooling water main pipe 56 is 33 m 3 (the supply flow rate of cooling water to the cooling water main pipe 56 is 390 m 3 /h) during the 5 minutes that the granular iron 66 is transported under the cooling water supply device 54. This is about 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.
• the water temperature in the space 59 between the conveyor 52 and the cooling water supply device 54 which had an initial water temperature of 65° C., was reduced to 50 to 58° C. In this way, it was confirmed that by using the granulated iron manufacturing apparatus 70 according to this embodiment, the water temperature in the space 59 between the conveyor 52 and the cooling water supply device 54 can be maintained in the range of 45° C. to 60° C.
• Figure 17 shows the results of simulating the temperature of granular iron on the conveyor 52. Assuming that a high-temperature object 66' simulating granular iron 66 at 700°C is present on the conveyor 52, the temperature change of the object 66' was simulated.
• Figure 17(a) is a side cross-sectional view showing the temperature of the object 66' before cooling
• Figure 17(b) is a front cross-sectional view showing the temperature of the object 66' before cooling
• Figure 17(c) is a front cross-sectional view showing the temperature of the object 66' 10 seconds after cooling water is supplied.
• the high-temperature object 66' is cooled by supplying cooling water through the slits, and 10 seconds after the cooling water is supplied, the surface temperature of the high-temperature object, which was 700°C, drops to around 400°C.
• the surface temperature of the granular iron 66 can be cooled from 700°C to around 400°C, and the granular iron 66 stacked on the conveyor 52 can be prevented from fusing and merging.

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  • 2024-10-10 WO PCT/JP2024/036217 patent/WO2025134489A1/ja active Pending
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