Grinding device, cement manufacturing device, and cement manufacturing method

Abstract

To improve manufacturing efficiency.SOLUTION: A crushing apparatus includes: a drum which stores a plurality of crushing balls, and is rotatable around a predetermined axis line; a driving part for rotating the drum around the axis line; a partition part which is arranged so as to partition a first region and a second region aligned in an axial direction at which the axis line extends in a space in the drum, and permits passage of powder to the second region from the first region; a supply part for supplying a crushing object including a cement clinker to the first region; and a discharge part for discharging a cooling liquid to the first region from one end in the axial direction of the drum. The discharge part is configured so as to discharge a plurality of droplets having an average particle diameter of 100 μm to 1,000 μm to the first region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a grinding device, a cement manufacturing device, and a cement manufacturing method. [Background technology]

[0002] Patent Document 1 discloses a method for producing cement in which Portland cement clinker and gypsum are simultaneously crushed in an atmosphere of high-temperature steam gas. Patent Document 2 discloses a method for treating industrial wastewater in which washing wastewater discharged from a semiconductor factory is added as a crushing aid to a crusher in a cement manufacturing facility and then disposed of. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-55008 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-2706 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a grinding device, a cement manufacturing device, and a cement manufacturing method that are useful for improving manufacturing efficiency. [Means for solving the problem]

[0005] A grinding device according to one aspect of the present disclosure includes a drum that accommodates a plurality of grinding balls and is rotatable about a predetermined axis, a drive unit that rotates the drum about the axis, a partition unit that is arranged to divide the space within the drum into a first region and a second region aligned in the axial direction along which the axis extends and that allows powder to pass from the first region to the second region, a supply unit that supplies material to be ground, including cement clinker, to the first region, and a discharge unit that discharges a cooling liquid from one end of the drum in the axial direction. The discharge unit is configured to discharge a plurality of droplets having an average particle size of 100 μm to 1000 μm into the first region.

[0006] If flowing water other than droplets is discharged, localized cooling can occur, reducing the cooling efficiency inside the drum. To avoid localized cooling, multiple droplets can be discharged. If a mist-like liquid with an average particle diameter of less than 100 μm is discharged into the first region, the droplets may flow from the first region to the second region through the partition due to their small size, causing the powder produced from the material to be pulverized to solidify in the partition. This can result in operational problems such as clogging in the partition, potentially reducing production efficiency. In contrast, the above-mentioned pulverizer discharges droplets with an average particle diameter of 100 μm or more, making it difficult for droplets to flow through the partition to the second region. This reduces the possibility of multiple droplets clogging the partition. Therefore, this pulverizer is useful for improving production efficiency.

[0007] The above-mentioned pulverization device may further include a suction unit that sucks gas from the second region and a dust collector that collects fine particles contained in the gas sucked by the suction unit. By setting the droplet size to 100 μm or more, the droplets are less likely to move even when suctioned by the suction unit. Therefore, while avoiding operational problems caused by droplets moving through the partition, the suction unit and the dust collector collect the fine particles floating in the drum, thereby suppressing operational problems caused by the fine particles. Therefore, this is further useful for improving production efficiency.

[0008] A grinding device according to one aspect of the present disclosure includes a drum that accommodates a plurality of grinding balls and is rotatable about a predetermined axis, a drive unit that rotates the drum about the axis, a partition unit that is arranged to divide the space within the drum into a first region and a second region that are aligned in the axial direction along which the axis extends and that allows powder to pass from the first region to the second region, a supply unit that supplies material to be ground, including cement clinker, to the first region, and a discharge unit that discharges coolant from one end of the drum in the axial direction. When the first region is divided into an upstream region and a downstream region at the center in the axial direction, an imaginary line extending in the direction in which the coolant is discharged by the discharge unit intersects with the side wall of the drum or the partition unit in the downstream region.

[0009] As the drum rotates, the temperature inside the drum rises due to collisions between the grinding balls and the drum's side wall or the object to be ground. It is also possible to position the discharge section so that the imaginary line intersects with the drum's side wall in the upstream region. However, in this case, more cooling liquid is supplied from the discharge section to the upstream region than to the downstream region. As a result, the amount of cooling liquid that hits the grinding balls in the downstream region is reduced, making it difficult to suppress temperature rise throughout the entire first region inside the drum. In the above-mentioned grinding device, the imaginary line extending in the discharge direction intersects with the drum's side wall or partition in the downstream region, allowing cooling liquid to hit the grinding balls in both the upstream and downstream regions, improving cooling efficiency. Therefore, this grinding device is useful for improving production efficiency.

[0010] The imaginary line may intersect with the side wall or partition of the drum in the range of 20% to 50% of the height of the first region. By making the height of the first region 20% or more, it is possible to prevent a large amount of coolant from hitting the material to be ground at the bottom of the drum and wasting a large amount of coolant reacting with the components contained in the material to be ground. Furthermore, by making the height of the first region 50% or less, it is possible to directly hit a large amount of coolant on the grinding balls. This further improves cooling efficiency. Therefore, it is even more useful for improving production efficiency in the process of grinding the material to be ground to produce cement.

[0011] The imaginary line may intersect with the side wall or partition of the drum in one of two regions obtained by dividing the first region at the center in the left-right direction perpendicular to the axial direction and the up-down direction, where the side wall of the drum moves from bottom to top along the circumferential direction around the axis. When the drum rotates, many grinding balls are present in one of the regions where the side wall of the drum moves from bottom to top along the circumferential direction around the axis. This configuration allows a large amount of coolant to directly hit the grinding balls, further improving cooling efficiency. Therefore, it is even more useful for improving production efficiency in a process of grinding a material to be ground to produce cement.

[0012] The pulverizer may further include a supply pipe for supplying the cooling liquid to the discharge part, and an injection part for supplying compressed air into the supply pipe. When starting or stopping the discharge of the cooling liquid, the injection part injects compressed air, thereby preventing the cooling liquid from adhering to the outer surface of the discharge part. This is therefore useful for preventing the formation of powder clumps on the outer surface of the discharge part due to the adhesion of the liquid.

[0013] A cement manufacturing apparatus according to one aspect of the present disclosure includes a manufacturing apparatus that produces cement clinker by burning cement raw materials, and the pulverizing device. Because the pulverizing device is included, the cement manufacturing apparatus is useful for improving manufacturing efficiency.

[0014] A method for producing cement according to one aspect of the present disclosure includes the steps of producing cement clinker by calcining cement raw materials and grinding an object to be ground, the object including cement clinker and gypsum. The grinding step includes the steps of rotating a drum containing a plurality of grinding balls about a predetermined axis, supplying the object to be ground to a first region of the drum, the first and second regions being defined by a partition that intersects the axis and allows powder to pass through, and discharging a cooling liquid containing a plurality of droplets from one end of the drum in the axial direction along which the axis extends into the first region using a discharge unit configured to discharge a plurality of droplets having an average particle size of 100 μm to 1000 μm. This manufacturing method, like the manufacturing apparatus described above, discharges a plurality of droplets having an average particle size of 100 μm to 1000 μm, which is useful for improving manufacturing efficiency.

[0015] A method for producing cement according to one aspect of the present disclosure includes the steps of: producing cement clinker by firing cement raw materials; and grinding an object to be ground, including cement clinker and gypsum. The grinding step includes the steps of: rotating a drum containing a plurality of grinding balls about a predetermined axis; supplying the object to be ground to a first region of the drum, which is formed by dividing the space inside the drum with a partition that intersects the axis and allows powder to pass through; and discharging a cooling liquid containing a plurality of droplets into the first region using a discharge unit from one end of the drum in the axial direction along which the axis of the drum extends. When the first region is divided into an upstream region and a downstream region at the center of the axial direction, an imaginary line extending in the direction of discharge of the cooling liquid by the discharge unit intersects with the side wall or the partition unit of the drum in the downstream region. This manufacturing method is useful for improving production efficiency because the cooling liquid can be applied to the grinding balls in both the upstream region and the downstream region.

[0016] The step of crushing the object to be crushed may further include a step of supplying compressed air into a supply pipe that supplies the cooling liquid to the discharge portion. The discharge of the cooling liquid may be started while the compressed air is being supplied into the supply pipe. The discharge of the cooling liquid may be stopped while the compressed air is being supplied into the supply pipe. In this case, it is useful to suppress the formation of powder clumps on the outer surface of the discharge portion due to adhesion of liquid to the outer surface of the discharge portion. [Effects of the Invention]

[0017] According to the present disclosure, a crushing device, a cement manufacturing device, and a cement manufacturing method that are useful for improving manufacturing efficiency are provided. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing an example of a cement manufacturing apparatus. [Figure 2] FIG. 2 is a perspective view schematically illustrating an example of a discharge section. [Figure 3] FIG. 3 is a plan view schematically illustrating an example of the inside of the drum. [Figure 4] FIG. 4 is a side view schematically showing an example of the inside of the drum. [Figure 5] FIG. 5 is a block diagram illustrating an example of a hardware configuration of the control device. [Figure 6] FIG. 6 is a flowchart showing an example of a series of processes executed by the control device. [Figure 7] FIG. 7 is a plan view schematically showing an example of the inside of the drum. [Figure 8] FIG. 8 is a side view schematically showing an example of the inside of the drum. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment will be described below with reference to the drawings. In the description, identical elements or elements having identical functions are given the same reference numerals, and duplicated explanations will be omitted. Some drawings show a Cartesian coordinate system defined by an X-axis, a Y-axis, and a Z-axis. In the following embodiment, the Z-axis corresponds to the vertical direction, and the X-axis and Y-axis correspond to the horizontal direction.

[0020] [Cement manufacturing equipment] The cement manufacturing apparatus 1 shown in Fig. 1 is an apparatus (facility) for manufacturing cement. The cement manufacturing apparatus 1 manufactures cement by carrying out a raw material process, a burning process, and a finishing process. The cement manufacturing apparatus 1 includes, for example, a cement clinker manufacturing apparatus 2 and a pulverizing apparatus 4.

[0021] The cement clinker manufacturing apparatus 2 produces cement clinker (hereinafter simply referred to as "clinker") by burning the cement raw materials produced in the raw material process. The cement clinker manufacturing apparatus 2 includes, for example, an NSP type preheater, a rotary kiln, and a clinker cooler. The clinker produced by the cement clinker manufacturing apparatus 2 is transported to the crushing device 4.

[0022] (Crushing equipment) The pulverizer 4 is a device that executes the pulverization process included in the finishing process. Specifically, the pulverizer 4 mixes the gypsum with the clinker while pulverizing the material to be pulverized, which contains clinker and gypsum. The pulverizer 4 is a device that performs finish pulverization (finish pulverizer), and the powder obtained by pulverization by the pulverizer 4 is discharged from the pulverizer 4 as cement. The pulverizer 4 includes, for example, a feeding device 6, a mill device 10, a suction device 30, a dust collector 40, a temperature measuring device 50, a cooling device 60, and a control device 100.

[0023] The feeding device 6 has a clinker feeding section 8 and a gypsum feeding section 9. The clinker feeding section 8 transports clinker and feeds (supplies) the clinker to the mill apparatus 10. The clinker feeding section 8 transports clinker, for example, from a clinker silo to the mill apparatus 10. The clinker feeding section 8 may transport and feed clinker that has been pulverized by a preliminary pulverizer such as a vertical mill. The gypsum feeding section 9 transports gypsum and feeds (supplies) the gypsum to the mill apparatus 10. The gypsum feeding section 9 transports gypsum, for example, from a gypsum storage area to the mill apparatus 10.

[0024] The mill apparatus 10 is an apparatus that crushes an object to be crushed using crushing media. The crushing media are balls (hereinafter referred to as "crushing balls") for crushing the object to be crushed, and are, for example, steel balls. The mill apparatus 10 is also called a tube mill (finishing mill). The mill apparatus 10 has, for example, a drum 12, a rotary drive unit 14, a partition unit 22, a supply chute 16, and a connection unit 18.

[0025] The drum 12 is a container that contains a plurality (a large number) of grinding balls. The drum 12 is rotatable about a predetermined axis Ax (see also FIGS. 3 and 4). The drum 12 extends, for example, in one horizontal direction (the X-axis direction in the drawings) and is formed in a cylindrical shape. The axis Ax extends along the extension direction of the drum 12 and substantially coincides with the center of the drum 12 in a cross section (the YZ plane in the drawings) perpendicular to the extension direction.

[0026] The drum 12 includes a side wall 12a arranged to surround the axis Ax. In a cross section perpendicular to the extension direction of the drum 12, the side wall 12a is ring-shaped. An internal space S for grinding the material to be ground is formed inside the drum 12. The internal space S is defined by the inner surface of the side wall 12a and is cylindrical. In the direction along the axis Ax, the material to be ground is supplied to the internal space S through an opening at one end of the side wall 12a, and cement is discharged through an opening at the other end of the side wall 12a. Note that the other end of the side wall 12a is not shown in FIG. 1. A step for lifting grinding balls may be provided on the inner wall of the side wall 12a.

[0027] The rotation drive unit 14 is a drive unit that rotates the drum 12 about the axis Ax. The rotation drive unit 14 includes a power source such as an electric motor. With the material to be crushed supplied into the drum 12 (internal space S), the rotation drive unit 14 rotates the drum 12 about the axis Ax. The rotation of the drum 12 about the axis Ax causes the crushing balls and the material to be crushed to collide with each other in the internal space S. As a result, the material to be crushed is crushed.

[0028] The partition 22 is a part that divides the internal space S into two regions that are aligned in a direction along the axis Ax. The partition 22 is formed so as to intersect (for example, perpendicular to) the axis Ax. Hereinafter, one of the regions separated by the partition 22 will be referred to as the "first region R1," and the other region will be referred to as the "second region R2." The first region R1 and the second region R2 are aligned in a direction along the axis Ax. In the direction along the axis Ax (axial direction), one end of the side wall 12a into which the material to be crushed is introduced, the first region R1, the second region R2, and the other end of the side wall 12a from which cement is discharged are aligned in this order.

[0029] The first region R1 accommodates a plurality of grinding balls 26, and the second region R2 accommodates a plurality of grinding balls 28. The diameter of the grinding balls 26 is larger than the diameter of the grinding balls 28. After the object to be ground is ground to a certain extent in the first region R1, the ground object is further ground into finer pieces in the second region R2. The partition 22 is configured to allow the passage of powder from the first region R1 to the second region R2, but to prevent the passage of the grinding balls. The partition 22 allows the passage of powder of a predetermined size or smaller from the object to be ground (powder) ground by the grinding balls 26 in the first region R1.

[0030] The partition portion 22 includes, for example, a first partition portion 22a located in the center around the axis Ax and a second partition portion 22b located on the outer periphery of the first partition portion 22a. The first partition portion 22a has a mesh structure with openings smaller than the diameter of the grinding balls. The second partition portion 22b is provided between the first partition portion 22a and the inner surface of the side wall 12a. The second partition portion 22b includes two wall portions 24a, 24b aligned in the direction of the axis Ax and forming a buffer space. One of the two wall portions 24a, 24b, which defines the first region R1, is provided with multiple openings (not shown).

[0031] When viewed in the direction in which the axis Ax extends, the opening may have a rectangular shape (or may be slit-shaped). The size of the opening is set so that the object to be crushed (powder) having a size that can be crushed in the second region R2 can pass through. In one example, when the opening is slit-shaped, the opening width in the short direction is approximately 5 mm to 15 mm. Powder is introduced through the opening into the buffer space defined by the second partition portion 22b. A connecting portion (not shown) that connects the buffer space and the second region R2 is provided in the second partition portion 22b, and when the buffer space is positioned upward, powder is discharged from the buffer space to the second region R2.

[0032] The supply chute 16 (supply section) supplies the material to be pulverized to the internal space S. Specifically, the supply chute 16 supplies at least clinker and gypsum to the first region R1 of the internal space S. The supply chute 16 is formed in a tubular shape. The supply chute 16 is formed, for example, in a cylindrical shape or a rectangular tubular shape with a square cross section. An inlet for the material to be pulverized is provided at one end of the supply chute 16. The inlet faces, for example, vertically upward.

[0033] The other end of the supply chute 16 is connected to an end of the drum 12 in the direction along the axis Ax (one end of the side wall 12a) via a connection part 18. An opening at the end of the supply chute 16 connected to the connection part 18 faces the drum 12 (internal space S). In a side view, the supply chute 16 may extend in a curved shape from one end where an inlet is provided to the other end connected to the connection part 18.

[0034] The connection part 18 connects the drum 12 and the supply chute 16, and guides the material to be crushed supplied from the supply chute 16 to the first region R1. The connection part 18 is located between the supply chute 16 and the end of the drum 12 in the direction along the axis Ax. The supply chute 16 may be formed in a cylindrical shape so that its diameter increases toward the first region R1.

[0035] In the mill apparatus 10, the supply chute 16, the connection portion 18, the first region R1, the partition portion 22, and the second region R2 are arranged in this order along the axis Ax. The material to be ground supplied from the supply chute 16 to the first region R1 is ground by the grinding balls 26 housed in the first region R1 as the drum 12 rotates. The material to be ground, which has been ground to a size that can pass through the opening of the partition portion 22, is introduced into the second region R2 through the partition portion 22. In the second region R2, the material to be ground is further ground by the grinding balls 28 housed in the second region R2 as the drum 12 rotates.

[0036] The suction device 30 (suction unit) is a fan that sucks gas from the second region R2 of the internal space S of the drum 12. The suction device 30 discharges the gas contained in the internal space S to the outside of the drum 12 so that the internal space S becomes negative pressure. The dust collector 40 (dust collection unit) is a device that collects fine powder from the gas sucked from the internal space S by the suction device 30. The dust collector 40 includes, for example, a filter that collects fine powder contained in the gas discharged from the internal space S. The suction device 30 and the dust collector 40 can collect fine powder (cement fine powder) floating in the internal space S.

[0037] The temperature measuring device 50 is a device that acquires information indicating the temperature of cement (hereinafter referred to as "temperature information"). The temperature measuring device 50 measures the temperature of cement immediately after it is discharged from a discharge port (not shown) of the drum 12, for example. The discharge port from which the cement is discharged is provided on the opposite side of the drum 12 from the end to which the material to be ground is supplied (in the second region R2). A partition plate with multiple slits formed therein may be provided at the discharge port, and the powder that passes through the slits may be discharged outside the drum 12 as cement. The temperature measuring device 50 may measure the temperature of cement in any manner. The temperature measuring device 50 outputs the acquired temperature information to the control device 100.

[0038] The cooling device 60 is a device that supplies a cooling liquid to the internal space S of the drum 12. As described above, the drum 12 rotates about the axis Ax to grind the material to be ground. As this rotation occurs, frictional heat is generated in each of the numerous grinding balls 26 in the internal space S (first region R1) due to collision with the material to be ground or the side wall 12a of the drum 12. If the temperature of the internal space S increases due to the generation of frictional heat, some of the gypsum contained in the material to be ground may turn into gypsum hemihydrate, which may result in a deterioration in the quality of the cement. The cooling device 60 supplies a cooling liquid to the internal space S to lower the temperature of the internal space S. The cooling device 60 may supply water (e.g., industrial water) as the cooling liquid, and the temperature of the water supplied by the cooling device 60 may be room temperature.

[0039] The cooling device 60 has a discharge unit 62. The discharge unit 62 discharges the cooling liquid from one end of the drum 12 (the end where the supply chute 16 is provided) toward the first region R1 of the internal space S. The discharge unit 62 may be a nozzle capable of discharging the cooling liquid. The discharge unit 62 is, for example, a nozzle (spray nozzle) that discharges water in the form of droplets. The discharge unit 62 may be a one-fluid nozzle or a two-fluid nozzle.

[0040] The average particle size (hereinafter referred to as "average particle size") of the plurality of droplets constituting the cooling liquid discharged from the discharge portion 62 is 100 μm to 1000 μm. In other words, the discharge portion 62 (e.g., a nozzle) is configured to discharge a plurality of droplets having an average particle size of 100 μm to 1000 μm into the first region R1. From the viewpoint of preventing the droplets from being sucked by the suction device 30, the minimum value of the average particle size of the plurality of droplets discharged from the discharge portion 62 may be 150 μm, 200 μm, 250 μm, or 300 μm. From the viewpoint of facilitating the manufacture of a discharge portion that discharges droplets, the maximum value of the average particle size of the plurality of droplets discharged from the discharge portion 62 may be 900 μm, 850 μm, 800 μm, 750 μm, or 700 μm or less.

[0041] The discharge unit 62 may form the discharged coolant into droplets by any method. The particle size of the droplets may be adjusted to a desired range by various known methods. The particle size of the droplets discharged from the discharge unit 62 may be measured by either an immersion method or a laser method. The average particle size of the droplets may be determined by the Sauter mean.

[0042] FIG. 2 schematically shows an example of a discharge portion 62 (nozzle). The discharge portion 62 is provided with, for example, one discharge port 62a facing the first region R1. The discharge port 62a facing the first region R1 means that a plane including the opening edge of the discharge port 62a (hereinafter referred to as the "opening plane") faces the first region R1. The opening plane is an imaginary plane whose outer edge is the opening edge of the discharge port 62a. If the opening edge of the discharge port 62a is circular, the opening plane is circular. The coolant from the discharge portion 62 is discharged along a central axis CA of the discharge portion 62 (nozzle body). The central axis CA is an axis that passes through the center of the opening plane and is perpendicular to the opening plane.

[0043] The discharge portion 62 may discharge multiple droplets so that the discharge range expands around the central axis CA. The spread shape (spray pattern) of the multiple droplets discharged from the discharge portion 62 may have a full circular cross section. When the cross section is full circular, the multiple droplets are scattered within a region inside a circle around a center that approximately coincides with the central axis CA on a plane perpendicular to the central axis CA. In the present disclosure, the central axis CA of the discharge portion 62 is defined as the discharge direction (discharge line) of the coolant from the discharge portion 62.

[0044] Next, an example of the direction in which the coolant is discharged by the discharge unit 62 will be described using Figures 3 and 4. Here, the terms "upstream" and "downstream" are used based on the flow of the material to be crushed in the mill apparatus 10. In the drum 12, the end of the drum 12 to which the material to be crushed is supplied is located upstream, and the end of the drum 12 from which the cement produced after the material to be crushed is discharged is located downstream. In addition, the terms "front-rear," "rear," and "left-right" are used based on the view from upstream to downstream. The front-rear direction corresponds to the X-axis direction, and the left-right direction corresponds to the Y-axis direction.

[0045] FIG. 3 is a schematic plan view of the drum 12 taken along a horizontal cross section passing through the axis Ax. FIG. 4 is a schematic side view of the drum 12 taken along a vertical cross section passing through the axis Ax. FIG. 4 shows a side view from left to right. As shown in FIG. 3, the discharge section 62 may be disposed to the left of the axis Ax in the left-right direction. The discharge section 62 may be disposed so that the discharge port 62a faces diagonally downward. To improve the cooling efficiency within the drum 12, the inclinations in the front-rear and up-down directions of a virtual line (hereinafter referred to as the "virtual line IL") extending in the direction in which the coolant is discharged by the discharge section 62 are set.

[0046] The first region R1 can be divided into two regions at the center in the axial direction along which the axis Ax extends (the boundary indicated by "BL" in the figure). Of the two regions divided by the boundary BL, the upstream region is referred to as "region R11," and the downstream region is referred to as "region R12." Region R11 is located between the upstream end of the side wall 12a of the drum 12 and the boundary BL, and region R12 is located between the boundary BL and the partition section 22. Region R11, region R12, and partition section 22 are arranged in this order along the axial direction of the axis Ax. In other words, region R12 (the downstream region) is located further back in the front-to-rear direction than region R11 (the upstream region).

[0047] The discharge portion 62 is disposed in the region R12 so that the imaginary line IL intersects with the inner wall that defines the first region R1. In one example, as shown in FIG. 3 or 4, the imaginary line IL intersects with the partition 22 located in the region R12. Hereinafter, the point where the imaginary line IL intersects with the partition 22 (more specifically, the surface of the partition 22 facing the first region R1) is defined as the "intersection point CP." The cooling efficiency inside the drum 12 is considered to depend on the amount of coolant that directly hits the grinding balls 26 contained in the drum 12. The horizontal and vertical positions of the intersection point CP are set from the viewpoint of increasing the amount of coolant that directly hits the grinding balls 26.

[0048] The imaginary line IL may intersect with the partition 22 in a region where the side wall 12a of the drum 12 moves from bottom to top in the circumferential direction about the axis Ax, of two regions obtained by dividing the first region R1 at the center in the left-right direction perpendicular to the axial direction of the axis Ax and the up-down direction. In the example shown in FIG. 3, the drum 12 rotates counterclockwise about the axis Ax when viewed from rear to front (from upstream to downstream). In this case, the imaginary line IL intersects with the partition 22 in the region located on the right side of the two regions obtained by dividing the first region R1 at the center in the left-right direction. The imaginary line IL may intersect with the axis Ax when viewed from above.

[0049] The imaginary line IL may intersect with the partition portion 22 in a range of 20% to 50% of the height of the first region R1. The height of the first region R1 corresponds to the length of the first region R1 in the vertical direction. In FIG. 4, the height of the first region R1 is indicated by "hd", and a height that is 20% of the height hd is indicated by "hm". A height that is 50% of the height hd corresponds to the height of the axis Ax. The intersection point CP is located at a height that is equal to or greater than the height hm and equal to or less than the height of the axis Ax in the vertical direction. From the viewpoint of further improving cooling efficiency, the minimum value of the height of the intersection point CP may be 25%, 30%, or 35% of the height hd instead of 20% of the height hd. The intersection point CP may be located in a range of 30% to 50% of the height of the first region R1. The lower limit of the height of the intersection point CP is set, for example, so as to be higher than the height of the material to be pulverized (cement raw material) remaining inside the drum 12 when the drum 12 is stationary and not rotating.

[0050] The intersection point CP does not mean the position where the cooling liquid (plurality of droplets) discharged from the discharge portion 62 reaches, but defines the direction of discharge from the discharge portion 62. The discharge portion 62 may discharge the plurality of droplets so that most of the cooling liquid (for example, 90% or more) does not reach the partition portion 22.

[0051] Returning to FIG. 1 , the cooling device 60 has, for example, a supply pipe 64, a liquid delivery device 70, and an injection device 80 in addition to the discharge portion 62. The supply pipe 64 is a pipe that guides the cooling liquid to the discharge portion 62 and supplies the cooling liquid to the discharge portion 62. The discharge portion 62 is provided at the tip (the end located downstream) of the supply pipe 64. The supply pipe 64 is provided so as to penetrate the side wall of the supply chute 16. In this case, a portion of the supply pipe 64 is located inside the supply chute 16, and another portion of the supply pipe 64 is located outside the supply chute 16. The tip of the supply pipe 64 and the discharge portion 62 may be located inside the supply chute 16. The supply pipe 64 may be provided at an angle relative to the horizontal direction. The supply pipe 64 may be inclined obliquely downward toward the first region R1.

[0052] The liquid delivery device 70 is a device that delivers the coolant to be discharged by the discharge unit 62 to the supply pipe 64. The liquid delivery device 70 has, for example, a liquid source 72, a delivery pipe 74, and an on-off valve 76. The liquid source 72 is a source of the coolant and includes, for example, a tank that stores the coolant and a pump that can pressure-feed the coolant. The pump included in the liquid source 72 adjusts the pressure of the coolant discharged from the discharge unit 62. The pump of the liquid source 72 may operate so that the discharge amount per unit time of the coolant discharged from the discharge unit 62 falls within a predetermined set range. The delivery pipe 74 connects the liquid source 72 to a coolant inlet provided in the supply pipe 64 and guides the coolant from the liquid source 72 into the supply pipe 64.

[0053] The on-off valve 76 switches between a state in which the discharge unit 62 discharges the cooling liquid and a state in which the discharge unit 62 does not discharge the cooling liquid. The on-off valve 76 is provided in the flow path formed by the delivery pipe 74, and switches the open / close state of the flow path in the delivery pipe 74 based on an operation command from the control device 100. For example, when the on-off valve 76 is in the open state, the cooling liquid is introduced from the liquid delivery device 70 into the supply pipe 64, and the cooling liquid is discharged from the discharge unit 62. When the on-off valve 76 is in the closed state, the introduction of the cooling liquid from the liquid delivery device 70 into the supply pipe 64 is stopped, and the discharge of the cooling liquid from the discharge unit 62 is stopped.

[0054] The injection device 80 (injection unit) is a device that injects compressed air into the supply pipe 64 so that the cooling liquid in the supply pipe 64 is discharged from the discharge unit 62. The air injected by the cooling device 60 (hereinafter referred to as "compressed air") is air in a state in which its volume has been reduced by increasing its pressure. The injection device 80 includes, for example, a supply source 82, a delivery pipe 84, and an open / close valve 86. The supply source 82 is a source of compressed air, such as an air compressor. The delivery pipe 84 connects the supply source 82 to a compressed air inlet provided in the supply pipe 64, and guides the compressed air from the supply source 82 into the supply pipe 64.

[0055] The on-off valve 86 switches between a state in which compressed air is injected into the supply pipe 64 and a state in which compressed air is not injected into the supply pipe 64. The on-off valve 86 is provided in the flow path formed by the delivery pipe 84, and switches the open / closed state of the flow path in the delivery pipe 84 based on an operation command from the control device 100. For example, when the on-off valve 86 is in the open state, compressed air is introduced from the spray device 80 into the supply pipe 64, and at least a portion of the coolant present in the supply pipe 64 is discharged from the discharge portion 62. When the on-off valve 86 is in the closed state, the introduction of compressed air from the spray device 80 into the supply pipe 64 stops.

[0056] The control device 100 is a computer that controls at least the temperature measuring device 50, the liquid delivery device 70, and the spray device 80. The control device 100 has a circuit 110, as shown in FIG. 5, for example. The circuit 110 includes at least one processor 112, a memory 114, a storage 116, an input / output port 118, and a timer 119. The storage 116 stores programs for controlling various devices included in the grinding device 4. The storage 116 is a computer-readable recording medium such as a hard disk, a non-volatile semiconductor memory, a magnetic disk, or an optical disk.

[0057] The memory 114 temporarily stores programs loaded from the storage 116, calculation results of the processor 112, etc. The processor 112 executes the programs in cooperation with the memory 114, thereby controlling each device included in the grinding device 4. The input / output port 118 inputs and outputs electrical signals between the temperature measuring device 50, the liquid delivery device 70, the spraying device 80, etc., in response to commands from the processor 112. The timer 119 counts clock pulses at a predetermined cycle in response to commands from the processor 112 to measure the elapsed time.

[0058] [Cement manufacturing method] Cement can be produced in the above-described cement manufacturing apparatus 1. The cement manufacturing process (manufacturing method) executed in the cement manufacturing apparatus 1 includes a clinker manufacturing process in which clinker is manufactured in the cement clinker manufacturing apparatus 2, and a pulverization process in which the clinker is pulverized in the pulverizer 4. The clinker manufacturing process includes a process in which the cement raw materials are preheated and calcined in a preheater, a process in which the preheated and calcined cement raw materials are fired in a rotary kiln to produce clinker, and a process in which the clinker discharged from the rotary kiln is cooled in a clinker cooler.

[0059] In the above-mentioned grinding process, a grinding device 4 is used to grind a grinding target obtained by adding at least gypsum to clinker (finish grinding process). By performing this grinding process, the clinker and gypsum are mixed while being ground, thereby obtaining cement. The grinding process includes a step of rotating the drum 12 about the axis Ax, a step of supplying the grinding target to the first region R1, and a cooling step of cooling the inside of the drum 12 by supplying a cooling liquid to the first region R1 using the discharge unit 62. In this cooling process, the cooling liquid containing a plurality of droplets is discharged from one end of the drum 12 in the direction along the axis Ax into the first region R1 using the discharge unit 62 configured to discharge a plurality of droplets having an average particle size of 100 μm to 1000 μm.

[0060] The control device 100 may control the temperature measuring device 50 and the cooling device 60 in the cooling step so that the temperature of the cement discharged from the drum 12 is maintained at or below a predetermined target temperature. The target temperature is set, for example, to a temperature at which a portion of the gypsum contained in the material to be pulverized does not change to gypsum hemihydrate. Figure 6 is a flowchart showing an example of a series of processes executed by the control device 100 in the cooling step.

[0061] In this series of processes, rotation of the drum 12 about the axis Ax by the rotation drive unit 14, introduction of the material to be crushed by the introduction device 6, suction by the suction device 30, and collection by the dust collector 40 are continuously performed. Also, in the initial state, the discharge of the cooling liquid from the discharge unit 62 is stopped. The control device 100 first executes step S11. In step S11, for example, the control device 100 acquires temperature information from the temperature measurement device 50 indicating the temperature of the cement immediately after it is discharged from the drum 12.

[0062] Next, the control device 100 executes step S12. In step S12, for example, the control device 100 determines whether the temperature indicated by the temperature information acquired in step S11 is above a predetermined set temperature. The predetermined set temperature is set to, for example, the same value as the target temperature. If it is determined in step S12 that the cement temperature is equal to or lower than the set temperature (step S12: NO), the process executed by the control device 100 returns to step S11. In this case, the control device 100 may repeatedly execute steps S11 and S12 at a predetermined cycle until the cement temperature exceeds the set temperature.

[0063] On the other hand, if it is determined in step S12 that the cement temperature is higher than the set temperature (step S12: YES), the process executed by the control device 100 proceeds to step S13. In step S13, for example, the control device 100 switches the on-off valve 86 of the injection device 80 from the closed state to the open state so as to start injecting compressed air into the supply pipe 64.

[0064] Next, the control device 100 executes steps S14 and S15. In step S14, for example, the control device 100 switches the on-off valve 76 of the liquid delivery device 70 from a closed state to an open state so as to start discharging the cooling liquid from the discharge unit 62. As a result, the discharge of the cooling liquid from the discharge unit 62 starts while the spray device 80 is injecting compressed air into the supply pipe 64. In step S15, for example, the control device 100 switches the on-off valve 86 from an open state to a closed state so as to stop injecting compressed air into the supply pipe 64.

[0065] Next, the control device 100 executes steps S16 and S17. In step S16, for example, the control device 100 acquires temperature information from the temperature measuring device 50, similar to step S11. In step S17, for example, the control device 100 determines whether the cement temperature indicated by the temperature information acquired in step S16 is below a predetermined set temperature. The set temperature used in step S17 may be set to the same value as the target temperature, similar to the set temperature used in step S12. Alternatively, the set temperature used in step S17 may be lower than the set temperature used in step S12.

[0066] If it is determined in step S17 that the cement temperature is equal to or higher than the set temperature (step S17: NO), the process executed by the control device 100 returns to step S16. In this case, the control device 100 may repeatedly execute steps S16 and S17 at a predetermined interval until the cement temperature falls below the set temperature. During this time, the discharge of the coolant from the discharge unit 62 continues.

[0067] Next, the control device 100 executes S18 and S19. In step S18, for example, the control device 100 switches the on-off valve 86 from a closed state to an open state so as to start injecting compressed air into the supply pipe 64. In step S19, for example, the control device 100 switches the on-off valve 76 from an open state to a closed state so as to stop the discharge of the coolant from the discharge unit 62. As a result, the discharge of the coolant from the discharge unit 62 is stopped while the injector 80 continues to inject compressed air into the supply pipe 64.

[0068] Next, the control device 100 executes step S20. In step S20, for example, the control device 100 switches the on-off valve 86 from an open state to a closed state so as to stop the injection of compressed air into the supply pipe 64. Thereafter, the process executed by the control device 100 returns to step S11, and the control device 100 repeatedly executes the series of processes from steps S11 to S20 while the pulverizer 4 is operating. Through the series of processes described above, the cooling device 60 is controlled so that the temperature of the cement discharged from the drum 12 approaches the target temperature.

[0069] The above-described series of processes is an example and can be modified as appropriate. In the above-described series of processes, the control device 100 may execute one step and the next step in parallel, or may execute each step in an order different from that of the above-described example. The control device 100 may omit any step, or may execute a process different from that of the above-described example in any step. The control device 100 may adjust the amount of coolant discharged from the discharge unit 62 according to the cement temperature, while continuing to supply the coolant from the cooling device 60, so that the cement temperature approaches a target temperature.

[0070] In the above example, the imaginary line IL extending along the direction in which the coolant is discharged from the discharge port 62 intersects the partition 22. However, the imaginary line IL may also intersect the side wall 12a in a region R12 at the rear of the first region R1. FIGS. 7 and 8 are a plan view and a side view, respectively, showing the interior of the drum 12 when the imaginary line IL intersects the side wall 12a in the region R12. In FIGS. 7 and 8, the intersection of the imaginary line IL and the side wall 12a is indicated by "CP1." The imaginary line IL intersects a portion of the side wall 12a located between the boundary BL and the partition 22.

[0071] The imaginary line IL may intersect with the side wall 12a in the right-hand region of the two regions obtained by dividing the first region R1 (region R12) at the center in the left-right direction. The intersection point CP1 is located to the right of the axis Ax when viewed from above. The imaginary line IL may intersect with the side wall 12a in a range of 20% to 50% of the height hd of the first region R1. The intersection point CP1 may be located in a range of 20% to 50% of the height hd of the first region R1, or in a range of 30% to 50% of the height hd of the first region R1.

[0072] The discharge portion 62 may be disposed to the right of the axis Ax when viewed from above. In this case, the imaginary line IL does not intersect with the axis Ax when viewed from above. The discharge portion 62 may be disposed on the axis Ax when viewed from above. The imaginary line IL may be horizontal, and the discharge portion 62 may discharge the coolant obliquely upward.

[0073] When viewed from rear to front (viewed from upstream to downstream), the drum 12 may rotate clockwise. In this case, the intersection points CP and CP1 may be located in a region of the first region R1 (region R12) to the left of the axis Ax.

[0074] As long as the imaginary line IL is positioned so as not to intersect with the side wall 12a in the region R11 but to intersect with the partition 22 or the side wall 12a in the region R12, the height of the intersection points CP and CP1 may be lower than 20% of the height hd of the first region R1 or higher than 50% of the height hd (the height of the axis Ax). Furthermore, when viewed from the rear to the front, and the drum 12 rotates counterclockwise, the intersection points CP and CP1 may be located to the left of the axis Ax in the first region R1.

[0075] [Effects of the embodiment] If flowing water, not droplets, is discharged from the discharge port, localized cooling may occur, reducing the cooling efficiency within the drum 12. To avoid localized cooling, multiple droplets may be discharged from the discharge port. If a mist-like liquid with an average particle diameter of less than 100 μm is discharged into the first region R1, the droplets may flow from the first region R1 to the second region R2 through the partition 22 due to their small size. This may cause the powder generated from the material to be pulverized to solidify in the partition 22. This may result in operational problems such as clogging of the partition 22, reducing production efficiency. In contrast, the pulverizer 4 discharges droplets with an average particle diameter of 100 μm or more from the discharge port 62, making it difficult for droplets to flow through the partition 22 to the second region R2. This reduces the possibility of multiple droplets clogging the partition 22. Therefore, the pulverizer 4 is useful for improving production efficiency.

[0076] The pulverizer 4 includes a suction device 30 that sucks gas from the second region R2, and a dust collector 40 that collects fine powder contained in the gas sucked by the suction device 30. By making the droplet size 100 μm or more, the droplets are less likely to move even when suctioned by the suction device 30. Therefore, while avoiding operational problems caused by the movement of droplets through the partition 22, the suction device 30 and the dust collector 40 can collect the fine powder floating in the internal space S, thereby suppressing operational problems caused by the fine powder. Therefore, this is even more useful for improving production efficiency.

[0077] As the drum rotates, the temperature inside the drum 12 rises due to collisions between the grinding balls (grinding balls 26) and the sidewall 12a of the drum 12 or the object to be ground. It is also possible to position the discharge section 62 so that an imaginary line IL extending in the direction of coolant discharge from the discharge section 62 intersects with the sidewall 12a in the upstream region R11. However, in this case, more coolant is supplied from the discharge section 62 to the upstream region R11 than to the downstream region R12. As a result, the amount of coolant that strikes the grinding balls 26 in the region R12 is reduced, making it difficult to suppress temperature rise throughout the entire first region R1 of the drum 12. In the grinding device 4, the imaginary line IL extending in the direction of discharge intersects with the sidewall 12a or the partition 22 in the region R12. This allows coolant to strike the grinding balls 26 in both the region R11 and the region R12, improving cooling efficiency. Therefore, the grinding device 4 is useful for improving production efficiency.

[0078] The imaginary line IL intersects with the side wall 12a or the partition 22 of the drum 12 in the range of 20% to 50% of the height hd of the first region R1. By making the height hd of the first region R1 20% or more, it is possible to prevent a large amount of coolant from hitting the material to be crushed located at the bottom of the drum 12 and wasting a large amount of coolant reacting with the components contained in the material to be crushed. Furthermore, by making the height hd of the first region R1 50% or less of the height hd, it is possible to allow a large amount of coolant to directly hit the grinding balls 26. This further improves cooling efficiency. Therefore, it is even more useful for improving production efficiency in the process of crushing the material to be crushed to produce cement.

[0079] The imaginary line IL intersects with the side wall 12a or the partition 22 in one of two regions obtained by dividing the first region R1 at the center in the left-right direction perpendicular to the axial direction and the up-down direction, where the side wall 12a of the drum 12 moves from bottom to top along the circumferential direction about the axis Ax. When the drum 12 rotates, many grinding balls 26 are present in the one region where the side wall 12a moves from bottom to top along the circumferential direction about the axis Ax. This configuration allows a large amount of coolant to directly hit the grinding balls 26, further improving cooling efficiency. Therefore, this is even more useful for improving production efficiency in the process of grinding a material to be ground to produce cement.

[0080] The pulverizer 4 includes a supply pipe 64 that supplies cooling liquid to the discharge part 62, and an injection device 80 that supplies compressed air into the supply pipe 64. When starting or stopping the discharge of cooling liquid, the injection device 80 injects compressed air (compressed air), thereby preventing the cooling liquid from adhering to the outer surface of the discharge part 62. This is therefore useful for preventing the formation of lumps of powder from the material to be pulverized due to the liquid adhering to the outer surface of the discharge part 62. [Example]

[0081] Next, the present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0082] The cooling efficiency was verified in Examples 1 to 3, which used the crushing device 4 shown in Figures 1 to 4 described above, and in Comparative Examples 1 to 3, which used crushing devices with cooling devices different from the cooling device 60. The conditions for Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Tables 1 and 2 below. Table 2 shows the details of the water spraying conditions in Table 1.

[0083] [Table 1]

[0084] [Table 2]

[0085] Specifically, in Examples 1 to 3, the cooling device 60 was controlled so as to maintain the cement temperature at the target temperature while the pulverizer 4 was operated continuously for 12 hours. A nozzle configured to discharge a plurality of droplets with an average particle diameter of 320 μm to 640 μm was used as the discharge unit 62. The imaginary line IL intersected at the partition unit 22, and the discharge unit 62 was positioned so that the intersection point CP was located in the region on the side where the pulverizing balls were lifted in the left-right direction, and at a height of 20% to 50% of the height hd of the first region R1. In order to maintain the cement temperature at the target temperature, the cooling device 60 was controlled in the same manner as the series of processes shown in FIG. 6 described above.

[0086] In Comparative Examples 1 to 3, a grinding machine without the cooling device 60 was operated continuously for 12 hours, and the cooling device of the grinding machine was controlled so as to maintain the cement temperature at a target temperature. A cooling device was used that supplied coolant to the clinker on the conveyor that supplied the clinker to the mill. In order to maintain the cement temperature at the target temperature, the cooling device was controlled in the same manner as the series of processes shown in Figure 6, except for the water injection point. The amount of coolant supplied from the cooling device was adjusted so that almost all of the coolant from the cooling device was supplied to (impacted on) the clinker being transported on the conveyor.

[0087] The average outside air temperature when testing Example 1 and Comparative Example 1, both of which had the same raw material composition and were set to the same target temperature, was 20°C. The average outside air temperature when testing Example 2 and Comparative Example 2, both of which had the same raw material composition and were set to the same target temperature, was 21°C. The average outside air temperature when testing Example 3 and Comparative Example 3, both of which had the same raw material composition and were set to the same target temperature, was 20°C. To evaluate the cooling efficiency, the ratio (wt%) of the amount of water injected to the total amount of raw material (material to be ground) charged into the mill was calculated. Table 3 shows the evaluation results.

[0088] [Table 3]

[0089] In Table 3, the clinker temperature before charging is the average temperature of the clinker before it is charged into the mill, and in Comparative Examples 1 to 3, it is the temperature of the clinker before the coolant is supplied by the cooling device. The clinker temperatures differ between corresponding Examples and Comparative Examples because the temperature of the clinker transported to the mill fluctuates depending on the operating conditions of the cement clinker production apparatus 2. The results in Table 3 show that in both Examples 1 to 3 and Comparative Examples 1 to 3, the temperature of the cement discharged from the mill (drum 12) is maintained at a value close to the target temperature.

[0090] Comparing the water injection rates of the corresponding Examples and Comparative Examples, it can be seen that the Examples have a lower water injection rate than the Comparative Examples. In other words, it can be seen that the Examples can achieve the target cement temperature with a smaller amount of water than the Comparative Examples, and that cooling efficiency is improved. [Explanation of symbols]

[0091] 1...cement manufacturing apparatus, 2...cement clinker manufacturing apparatus, 4...grinding device, 12...drum, 12a...side wall, 14...rotation drive unit, 16...supply chute, 22...partition unit, R1...first region, R2...second region, 30...suction device, 40...dust collector, 62...discharge unit, IL...imaginary line, CP, CP1...intersection, 64...supply piping, 80...injection device.

Claims

1. a drum that accommodates a plurality of grinding balls and is rotatable about a predetermined axis; a drive unit that rotates the drum around the axis; a partition portion disposed so as to partition a space within the drum into a first region and a second region aligned in an axial direction in which the axis extends, the partition portion allowing passage of powder from the first region to the second region; a supply unit that supplies a material to be ground, including cement clinker, to the first region; a discharge portion that discharges the cooling liquid from one end of the drum in the axial direction to the first region, the discharge portion is disposed at a position different from the axis, and when viewed from vertically above, an imaginary line extending in a direction in which the coolant is discharged by the discharge portion intersects with the axis, A crushing device wherein, when the first region is divided into an upstream region and a downstream region at the center in the axial direction, the imaginary line intersects with the side wall of the drum or the partition portion in the downstream region.

2. The crushing device according to claim 1, wherein the imaginary line intersects with the side wall of the drum or the partition in a range of 20% to 50% of the height of the first region.

3. The imaginary line intersects with the side wall of the drum or the partition portion in one of two regions obtained by dividing the first region at the center in a left-right direction perpendicular to the axial direction and the up-down direction, where the side wall of the drum moves from bottom to top along the circumferential direction around the axis. The crushing device according to claim 1 or 2.

4. a supply pipe for supplying the cooling liquid to the discharge portion; The crushing device according to any one of claims 1 to 3, further comprising: an injection unit that supplies compressed air into the supply pipe.

5. a manufacturing device for producing cement clinker by burning cement raw materials; A cement manufacturing apparatus comprising the pulverizing device according to any one of claims 1 to 4.

6. generating cement clinker by burning the cement raw materials; and grinding an object to be ground, the object including cement clinker and gypsum, The step of crushing the object to be crushed includes: A step of rotating a drum containing a plurality of grinding balls about a predetermined axis; a step of supplying the material to be crushed to a first region of a second region formed by dividing a space in the drum by a partition portion that intersects the axis and allows powder to pass through; and discharging the cooling liquid containing a plurality of droplets from one end of the drum in the axial direction along which the axis line extends, using a discharge part, into the first region, the discharge portion is disposed at a position different from the axis, and when viewed from vertically above, an imaginary line extending in a direction in which the coolant is discharged by the discharge portion intersects with the axis, A method for manufacturing cement, wherein when the first region is divided into an upstream region and a downstream region at the center in the axial direction, the imaginary line intersects the side wall of the drum or the partition portion in the downstream region.

7. the step of crushing the object to be crushed further includes the step of supplying compressed air into a supply pipe that supplies the cooling liquid to the discharge portion, starting to discharge the cooling liquid while compressed air is being supplied into the supply pipe; The method for producing cement according to claim 6, wherein the discharge of the cooling liquid is stopped while compressed air is being supplied into the supply pipe.

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