Classifier, power generation equipment, and classifier operation method

Abstract

The object of the present invention is to improve classification performance. A rotary classifier (16) classifies pulverized solid fuel introduced together with primary air into coarse powder fuel (B1) larger than a specified particle size and fine powder fuel (B2) smaller than a specified particle size. The rotary classifier (16) includes a plurality of scrapers (60) extending in the vertical direction and arranged circumferentially on an imaginary circle (V) centered on a central axis (C) extending in the vertical direction, and introduces solid fuel together with a conveying gas flowing from the radial outside toward the inside. The scraper (60) has a collision surface (61) on which the introduced pulverized fuel collides, ejecting the coarse powder fuel (B1) larger than a specified particle size in the collided pulverized fuel in the radial outward direction and ejecting the fine powder fuel (B2) smaller than a specified particle size in the radial inward direction. In the collision surface (61), the angle formed by the tangent line of the imaginary circle (V) and the perpendicular line relative to the collision surface (61) is larger on the radially outer side than on the radially inner side.

Description

Technical Field

[0001] The invention relates to a classifier, power generation equipment and an operating method of the classifier. Background Art

[0002] Conventionally, solid fuels (carbon-containing solid fuels) such as coal or biomass fuels are pulverized into a fine powder within a specified particle size range using a pulverizer (mill) and supplied to a combustion device. The mill crushes the solid fuel, such as coal or biomass fuel, fed into the pulverization table by sandwiching it between the pulverization table and pulverizing rollers. The pulverized solid fuel (hereinafter referred to as "pulverized fuel") is sieved by a classifier using a conveying gas (primary air) supplied from the periphery of the pulverization table. The pulverized solid fuel is then conveyed to a boiler and combusted in a combustion device. In a thermal power generation facility, steam is generated by heat exchange with the combustion gas generated by the combustion of the pulverized fuel in the boiler. This steam is used to rotate and drive a steam turbine, which in turn rotates and drives a generator connected to the steam turbine, thereby generating electricity.

[0003] As one type of classifier installed in a mill, for example, a rotary classifier is known. A rotary classifier has multiple scrapers arranged at equal intervals along the circumference around a rotational axis. A rotary classifier is a device that classifies pulverized fuel by causing the heavy, centrifugal force acting on the coarse fuel (pulverized fuel with a particle size larger than a specified size) to be ejected toward the outer periphery of the scrapers, while the light, fine fuel (pulverized fuel with a particle size smaller than a specified size) that is subjected to a strong conveying force generated by the primary air flow passes toward the inner periphery of the scrapers.

[0004] The rotary classifier has a main body that rotates about a rotation axis. The main body holds the scraper blades in place, allowing them to orbit about the rotation axis. The main body is held by bearings and rotates at a predetermined speed by a power source such as a motor. By varying this speed, the force acting on the pulverized fuel can be adjusted to achieve a desired fineness (classification performance).

[0005] Typically, the scraper blades of a rotary classifier are flat-plate shaped. However, in order to improve classification performance (such as ejecting coarse pulverized fuel toward the outer periphery of the scraper blades and allowing fine pulverized fuel to pass between the scraper blades), the scraper blades of a rotary classifier may be shaped other than a simple flat plate (for example, see Patent Document 1).

[0006] Patent Document 1 describes a rotary classifier in which the angle formed by the upstream end (inlet end) of a plurality of classifying blades rotating about a vertical axis with the direction of the rotation radius is larger, and the angle is smaller at the downstream end (outlet end). In other words, Patent Document 1 describes a rotary classifier in which the classifying blades are bent.

[0007] Previous technical literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 7-51630 Summary of the Invention

[0010] Technical issues to be solved by the invention

[0011] The classifying blade (scraper) described in Patent Document 1 is bent at different angles (relative to the radial direction) at the inlet side (radially outer portion) and the outlet side (radially inner portion). Generally, the particle size range of the pulverized fuel that can be ejected toward the outer periphery changes depending on the angle of the scraper. Therefore, in the scraper described in Patent Document 1, pulverized fuel of an intermediate particle size, which is ejected toward the outer periphery at the inlet side of the scraper but cannot be ejected toward the outer periphery at the outlet side, sometimes collides with the scraper. In this case, the classification results differ significantly depending on whether the scraper collides with the outlet side or the inlet side.

[0012] Whether the pulverized fuel collides with the inlet or outlet side of the scraper blade is determined by the position at which the pulverized fuel enters the rotary classifier. Specifically, if the pulverized fuel enters the rotary classifier from a radially distant location, the pulverized fuel collides with the outlet side; if the pulverized fuel enters from a radially close location, the pulverized fuel collides with the inlet side.

[0013] Thus, in the device described in Patent Document 1, when pulverized fuel of an intermediate particle size enters the rotary classifier from far away from the scraper blades and collides with the inlet side portion of the scraper blades, the colliding pulverized fuel is ejected toward the outer periphery and returned to the pulverization section (pulverization table). On the other hand, when pulverized fuel of an intermediate particle size enters the rotary classifier from near the scraper blades and collides with the outlet side portion of the scraper blades, the colliding pulverized fuel passes through the inner periphery and is directed to the boiler. It is difficult to control the position at which the pulverized fuel enters the rotary classifier. Therefore, in the device described in Patent Document 1, whether the pulverized fuel of an intermediate particle size collides with the inlet side portion and is ejected toward the outer periphery or collides with the outlet side portion and passes toward the inner periphery is random depending on the particle size. In other words, even pulverized fuel of the same particle size can be classified (ejected toward the outer periphery) or not classified (ejected toward the inner periphery). Therefore, it is possible that the pulverized fuel cannot be classified based on the target particle size with high precision, that is, the classification performance may be reduced.

[0014] In particular, the greater the angular difference between the inlet and outlet portions, the wider the range of particle sizes within which classification is random, significantly reducing classification performance. Furthermore, even changing the blade speed only changes the upper or lower limit of the range within which classification is random, failing to address the reduced classification performance.

[0015] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a classifier, a power generation facility, and a method for operating the classifier, which can improve the classification performance.

[0016] Means for solving technical problems

[0017] In order to solve the above-mentioned problems, the classifier, power generation equipment, and classifier operation method of the present invention adopt the following aspects.

[0018] A classifier according to one embodiment of the present invention is a classifier for classifying particles introduced together with a conveying gas into particles larger than a specified particle size and particles smaller than a specified particle size, the classifier comprising: a plurality of scrapers extending in an up-down direction, arranged circumferentially on an imaginary circle centered on a central axis extending in the up-down direction, and introducing the particles together with the conveying gas from the radial outside toward the inside, the scraper having a collision surface, on which the introduced particles collide, and the particles larger than a specified particle size among the collided particles are ejected in the radial outward direction, and the particles smaller than the specified particle size are ejected in the radial inward direction, and in the collision surface, an angle formed by a tangent of the imaginary circle and a perpendicular to the collision surface is larger on the radial outside than on the radial inside.

[0019] A method for operating a classifier according to one embodiment of the present invention is a method for operating a classifier that classifies particles introduced together with a conveying gas into particles larger than a specified particle size and particles smaller than a specified particle size, wherein the classifier includes a plurality of scrapers extending in a vertical direction and arranged circumferentially on an imaginary circle centered on a central axis extending in the vertical direction, and introducing the particles together with the conveying gas from a radially outer side toward an inner side, the scrapers having a collision surface on which the introduced particles collide, ejecting the particles larger than the specified particle size among the collided particles in the radially outer direction and ejecting the particles smaller than the specified particle size in the radially inner direction, the collision surface having a larger angle formed by a tangent to the imaginary circle and a perpendicular to the collision surface on the radially outer side than on the radially inner side, and the method for operating the classifier including the step of decomposing the particles into the particles larger than the specified particle size and the particles smaller than the specified particle size by the scrapers.

[0020] Effects of the Invention

[0021] According to the present invention, classification performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a diagram showing the configuration of a solid fuel pulverizing device and a boiler according to an embodiment of the present invention.

[0023] Figure 2 It is a longitudinal sectional view showing a rotary classifier according to an embodiment of the present invention.

[0024] Figure 3 It is a horizontal cross-sectional view showing a rotary classifier according to an embodiment of the present invention.

[0025] Figure 4 It is a horizontal cross-sectional view showing a wiper blade according to an embodiment of the present invention.

[0026] Figure 5 This is a graph showing the relationship between the outward force acting on the scraper blade for pulverizing fuel and the passing characteristics and the distance from the scraper blade inlet in the embodiment of the present invention.

[0027] Figure 6 This is a graph showing the classification performance of the rotary classifier according to the embodiment of the present invention.

[0028] Figure 7 It is a diagram showing a modified example of the wiper blade according to the embodiment of the present invention.

[0029] Figure 8 It is a diagram showing a modified example of the wiper blade according to the embodiment of the present invention.

[0030] Figure 9 It is a diagram showing a modified example of the wiper blade according to the embodiment of the present invention.

[0031] Figure 10 It is a diagram showing a modified example of the wiper blade according to the embodiment of the present invention.

[0032] Figure 11 Yes Figure 10 XI-XI sectional view.

[0033] Figure 12 Yes Figure 10 Cross-sectional view taken along the XII-XII direction.

[0034] Figure 13 It is a diagram showing a modified example of the rotary classifier according to the embodiment of the present invention.

[0035] Figure 14 It is a diagram showing a modified example of the wiper blade according to the embodiment of the present invention.

[0036] Figure 15 It is a figure which shows the scraper blade which concerns on the comparative example of this invention.

[0037] Figure 16 It is a figure which shows the scraper blade which concerns on the comparative example of this invention.

[0038] Figure 17 This is a graph showing the relationship between the outward force acting on the scraper blade for pulverizing fuel and the passing characteristics and the distance from the scraper blade inlet in a comparative example of the present invention.

[0039] Figure 18A This is a graph showing the relationship between the size of pulverized fuel passing through a flat blade and the passing characteristics.

[0040] Figure 18B This is a graph showing the relationship between the size of pulverized fuel passing through a flat blade and the distance from the blade inlet.

[0041] Figure 19 is a schematic diagram showing the classification effect in air flow.

[0042] Figure 20 This is a graph showing the relationship between the particle size of the pulverized fuel that collides with the scraper and the distance from the inlet of the scraper.

[0043] Figure 21 This is a graph showing the classification performance of a rotary classifier according to a comparative example of the present invention.

[0044] Figure 22 It is a figure which shows the scraper blade which concerns on the comparative example of this invention.

[0045] Figure 23 This is a graph showing the relationship between the outward force acting on the scraper blade for pulverizing fuel and the passing characteristics and the distance from the scraper blade inlet in a comparative example of the present invention.

[0046] Figure 24 This is a graph showing the classification performance of a rotary classifier according to a comparative example of the present invention. DETAILED DESCRIPTION

[0047] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A power generation facility 1 according to this embodiment includes a solid fuel pulverizing device 100 and a boiler 200 .

[0048] In the following description, "up" indicates the vertically upper direction, and "up" in upper part or upper surface indicates the vertically upper part. Similarly, "down" indicates the vertically lower part. The vertical direction is not exact and includes errors.

[0049] As an example, the solid fuel pulverizing device 100 of this embodiment pulverizes solid fuel (carbon-containing solid fuel) such as coal or biomass fuel to generate pulverized fuel and supplies it to the burner (combustion device) 220 of the boiler 200 .

[0050] Include Figure 1 The power generation facility 1 of the solid fuel pulverizing device 100 and the boiler 200 shown includes one solid fuel pulverizing device 100 , but a system may be provided with a plurality of solid fuel pulverizing devices 100 corresponding to each of the plurality of burners 220 of one boiler 200 .

[0051] The solid fuel pulverizing device 100 of the present embodiment includes a mill (pulverizer) 10 , a coal feeder (fuel supplier) 20 , an air blower (transport gas supplier) 30 , a state detector 40 , and a controller (determination unit) 50 .

[0052] The mill 10 for pulverizing solid fuel such as coal or biomass fuel supplied to the boiler 200 into fine powder, that is, pulverized fuel, may be a type that pulverizes only coal, only biomass fuel, or both biomass fuel and coal.

[0053] Biomass fuels, as used herein, refer to renewable, organic resources derived from living organisms, such as thinning wood, wood waste, driftwood, grasses, waste, sludge, tires, and recycled fuels (pellets or chips) derived from these, and are not limited to the materials listed here. Biomass fuels absorb carbon dioxide during their growth, becoming carbon-neutral and not emitting carbon dioxide, a global warming gas. Therefore, various studies are underway on their use.

[0054] The mill 10 includes: a housing 11; a pulverizing table (rotating table) 12; a pulverizing roller 13; a drive unit 14; a mill motor 15 connected to the drive unit 14 and rotating the pulverizing table 12; a rotary classifier 16; a fuel supply unit 17; and a classifier motor 18 that rotates the rotary classifier 16.

[0055] The housing 11 is a frame formed in a vertically extending cylindrical shape and accommodating the pulverizing table 12 , the rollers 13 , the rotary classifier 16 , and the fuel supply unit 17 .

[0056] A fuel supply unit 17 is mounted in the center of the ceiling 42 of the housing 11. The fuel supply unit 17 supplies solid fuel introduced from the silo 21 into the housing 11. The fuel supply unit 17 is vertically arranged at the center of the housing 11, with its lower end extending into the housing 11.

[0057] A driving unit 14 is provided near the bottom portion 41 of the housing 11 , and a pulverizing table 12 is rotatably arranged to be rotated by a driving force transmitted from a mill motor 15 connected to the driving unit 14 .

[0058] The pulverizing table 12 is a circular member when viewed from above, and is positioned opposite the lower end of the fuel supply unit 17. The upper surface of the pulverizing table 12 may have an inclined shape, with a lower center portion and gradually rising toward the outside, or may have an outer periphery that curves upward. The fuel supply unit 17 supplies solid fuel (e.g., coal or biomass fuel in this embodiment) from above to the pulverizing table 12 below. The pulverizing table 12 pulverizes the supplied solid fuel between it and the pulverizing rollers 13.

[0059] When solid fuel is fed from the fuel supply unit 17 toward the approximately center of the pulverizing table 12, the solid fuel is directed toward the outer periphery of the pulverizing table 12 by the centrifugal force generated by the rotation of the pulverizing table 12 and is crushed between the pulverizing table 12 and the pulverizing rollers 13. The crushed solid fuel is then swept upward by conveying gas (hereinafter referred to as primary air) introduced from the conveying gas flow path (hereinafter referred to as primary air flow path) 100a and directed to the rotary classifier 16.

[0060] An air blow port (not shown) is provided on the outer periphery of the pulverizing table 12 so that the primary air flowing in from the primary air flow path 100a flows out to the space above the pulverizing table 12 in the shell 11. A rotating blade (not shown) is provided on the air blow port to apply a rotational force to the primary air blown out from the air blow port. The primary air to which the rotational force is applied by the rotating blade becomes an air flow with a rotational velocity component and transports the solid fuel pulverized on the pulverizing table 12 to the rotary classifier 16 located above the shell 11. In addition, the pulverized solid fuel that is larger than the specified particle size is classified by the rotary classifier 16, or falls without reaching the rotary classifier 16 and returns to the pulverizing table 12 to be pulverized again between the pulverizing table 12 and the pulverizing roller 13.

[0061] The pulverizing roller 13 is a rotating body that pulverizes the solid fuel supplied from the fuel supply unit 17 to the pulverizing table 12. The pulverizing roller 13 is pressed against the upper surface of the pulverizing table 12 and pulverizes the solid fuel in cooperation with the pulverizing table 12.

[0062] exist Figure 1 Although only one pulverizing roller 13 is typically shown, multiple pulverizing rollers 13 may be arranged at regular intervals in the circumferential direction so as to press against the upper surface of the pulverizing table 12. For example, three pulverizing rollers 13 may be arranged at regular intervals in the circumferential direction at angular intervals of 120° on the outer circumference. In this case, the portions of the three pulverizing rollers 13 that contact (press against) the upper surface of the pulverizing table 12 are equidistant from the rotational axis of the pulverizing table 12.

[0063] The pulverizing roller 13 is supported by the journal head 45 so as to be able to swing vertically and move freely toward or away from the upper surface of the pulverizing table 12. With its outer peripheral surface in contact with the solid fuel on the upper surface of the pulverizing table 12, as the pulverizing table 12 rotates, the pulverizing roller 13 receives the rotational force from the pulverizing table 12 and rotates in conjunction therewith. When solid fuel is supplied from the fuel supply unit 17, the solid fuel is pressed and pulverized between the pulverizing roller 13 and the pulverizing table 12.

[0064] The support arm 47 of the journal head 45 is supported by a horizontal support shaft 48 in its middle portion and by the side surfaces of the housing 11, allowing the crushing roller 13 to swing vertically about the support shaft 48. Furthermore, a pressing device 49 is provided at the upper end portion located vertically above the support arm 47. The pressing device 49 is fixed to the housing 11 and applies a load to the crushing roller 13 via the support arm 47 and other means, thereby pressing the crushing roller 13 against the crushing table 12.

[0065] The driving unit 14 is a device that transmits driving force to the pulverizing table 12 to rotate the pulverizing table 12 about the central axis. The driving unit 14 is connected to the mill motor 15 and transmits the driving force of the mill motor 15 to the pulverizing table 12.

[0066] The rotary classifier 16 is installed in the upper portion of the housing 11 and has a hollow, generally inverted conical shape. The rotary classifier 16 includes a plurality of scrapers 60 extending in the vertical direction on its outer periphery. The scrapers 60 are arranged at predetermined intervals (equally spaced) around the central axis C of the rotary classifier 16.

[0067] The rotary classifier 16 is a device that classifies the solid fuel (hereinafter, the solid fuel to be pulverized is referred to as "pulverized fuel") pulverized by the pulverizing table 12 and the pulverizing roller 13 into pulverized fuel larger than a predetermined particle size (for example, 70 to 100 μm in coal) (hereinafter, pulverized fuel exceeding the predetermined particle size is referred to as "coarse powder fuel") and pulverized fuel smaller than a predetermined particle size (hereinafter, pulverized fuel smaller than the predetermined particle size is referred to as "fine powder fuel"). The rotary classifier 16 that performs classification by rotation is also called a rotary separator, and a rotary driving force is applied to the classifier motor 18 controlled by the control unit 50 so as to rotate the cylindrical shaft 71 (refer to FIG. 1 ) extending in the vertical direction of the housing 11. Figure 2 ) is the center and rotates around the fuel supply unit 17. In addition, the details of the rotary classifier 16 will be described later.

[0068] Alternatively, a fixed-type classifier including a fixed hollow inverted conical housing and a plurality of fixed rotating blades provided on the outer periphery of the housing instead of the scraper 60 may be used as the classifier.

[0069] Of the pulverized fuel that reaches the rotary classifier 16, the large-diameter coarse pulverized fuel is knocked off by the scraper 60 due to the relative balance between the centrifugal force generated by the rotation of the scraper 60 and the centripetal force generated by the primary air flow. The pulverized fuel returns to the pulverization table 12 and is pulverized again. The fine pulverized fuel is then introduced into the outlet port 19 located at the ceiling portion 42 of the housing 11. The fine pulverized fuel classified by the rotary classifier 16 is discharged from the outlet port 19 along with the primary air into the fine pulverized fuel supply flow path 100b and supplied to the burner 220 of the boiler 200. When the solid fuel is coal, the fine pulverized fuel supply flow path 100b is also called a pulverized coal pipe.

[0070] The fuel supply unit 17 is installed so that its lower end extends vertically into the interior of the housing 11, penetrating the ceiling 42 of the housing 11. Solid fuel introduced from the upper portion of the fuel supply unit 17 is supplied to the substantially central area of ​​the pulverizing table 12. Solid fuel is supplied to the fuel supply unit 17 from the coal feeder 20.

[0071] The coal feeder 20 includes a conveyor unit 22 and a coal feeder motor 23. The conveyor unit 22 is, for example, a belt conveyor, and uses the driving force applied by the coal feeder motor 23 to convey the solid fuel discharged from the lower end of the drop pipe 24 located directly below the hopper 21 to the upper part of the fuel supply unit 17 of the mill 10, and then discharge the solid fuel into the fuel supply unit 17.

[0072] Normally, the mill 10 is supplied with primary air for conveying pulverized fuel to the burner 220, and its pressure is higher than that of the coal feeder 20 or the silo 21. Fuel is held in a stacked state within a drop pipe 24, a tube extending vertically directly below the silo 21. The layer of solid fuel stacked within the drop pipe 24 ensures sealing to prevent the primary air and pulverized fuel from flowing back toward the silo 21 from the mill 10.

[0073] The supply amount of the solid fuel supplied to the mill 10 is adjusted by, for example, the moving speed of the belt conveyor of the transport unit 22 .

[0074] The air supply unit 30 dries the pulverized fuel and supplies primary air to be supplied to the rotary classifier 16 into the casing 11 .

[0075] In this embodiment, in order to appropriately adjust the flow rate and temperature of the primary air sent into the interior of the shell 11, the air supply unit 30 has a primary air fan (PAF: Primary Air Fan) 31, a hot air flow path 30a, a cold air flow path 30b, a hot air damper 30c and a cold air damper 30d.

[0076] In this embodiment, the hot air flow path 30a supplies a portion of the air (outside air) delivered from the primary air blower 31 as hot air heated by, for example, a heat exchanger 34 such as an air preheater. A hot air damper 30c is provided downstream of the hot air flow path 30a. The opening of the hot air damper 30c is controlled by the control unit 50. The flow rate of the hot air supplied from the hot air flow path 30a is determined by the opening of the hot air damper 30c.

[0077] The cold air flow path 30b supplies a portion of the air delivered from the primary air blower 31 as normal temperature cold air. A cold air damper 30d is provided on the downstream side of the cold air flow path 30b. The opening degree of the cold air damper 30d is controlled by the control unit 50. The flow rate of the cold air supplied from the cold air flow path 30b is determined by the opening degree of the cold air damper 30d.

[0078] In this embodiment, the flow rate of the primary air becomes the total flow rate of the hot air supplied from the hot air flow path 30a and the flow rate of the cold air supplied from the cold air flow path 30b, and the temperature of the primary air is determined by the mixing ratio of the hot air supplied from the hot air flow path 30a and the cold air supplied from the cold air flow path 30b, and is controlled by the control unit 50.

[0079] Furthermore, by introducing a portion of the combustion gas discharged from the boiler 200 via a gas recirculation fan (not shown) into the hot air supplied from the hot air flow path 30a and mixing them, the oxygen concentration of the primary air sent into the casing 11 from the primary air flow path 100a can be adjusted.

[0080] In this embodiment, the measured or detected data is transmitted to the control unit 50 by the state detection unit 40 of the mill 10. The state detection unit 40 of this embodiment is, for example, a differential pressure measuring device that measures the differential pressure between the pressure at the portion where primary air flows from the primary air flow path 100a into the interior of the housing 11 and the pressure at the outlet port 19 where primary air and pulverized fuel are discharged from the interior of the housing 11 to the pulverized fuel supply flow path 100b, as the differential pressure of the mill 10. Increases and decreases in this differential pressure of the mill 10 correspond to increases and decreases in the amount of pulverized fuel circulating between the vicinity of the rotary classifier 16 and the vicinity of the pulverizing table 12 within the housing 11 due to the classification effect of the rotary classifier 16. That is, by adjusting the rotational speed of the rotary classifier 16 according to the differential pressure of the mill 10, the amount of pulverized fuel discharged from the outlet port 19 can be adjusted relative to the supply amount of solid fuel supplied to the mill 10, so that the amount of pulverized fuel corresponding to the supply amount of solid fuel to the mill 10 can be stably supplied to the burner 220 provided in the boiler 200 within a range where the particle size of the pulverized fuel does not affect the combustibility of the burner 220.

[0081] Furthermore, the state detection unit 40 of this embodiment is, for example, a temperature measuring device. It detects the temperature of the primary air supplied to the interior of the housing 11 (the temperature of the primary air at the mill inlet) or the temperature of the primary air from the space above the pulverizing table 12 within the housing 11 to the outlet port 19, thereby controlling the air supply unit 30 so that the upper limit temperature does not exceed the upper limit temperature. The upper limit temperature is determined by taking into account factors such as the possibility of ignition of the solid fuel. Furthermore, the primary air is cooled by being transported within the housing 11 while drying and pulverizing the fuel, and the temperature of the primary air at the outlet port 19 is, for example, approximately 60 to 90 degrees Celsius.

[0082] The control unit 50 is a device that controls each unit of the solid fuel pulverizing device 100 .

[0083] The control unit 50 can transmit a driving instruction to the mill motor 15 and control the rotation speed of the pulverizing table 12 , for example.

[0084] The control unit 50, for example, transmits a drive instruction to the classifier motor 18 and controls the rotational speed of the rotary classifier 16 to adjust the classification performance. This allows the differential pressure of the mill 10, i.e., the amount of pulverized fuel circulating within the mill 10, to be appropriately within a predetermined range, thereby enabling a stable supply of pulverized fuel to the burner 220. The classification performance refers to the performance required for classification, such as the classification characteristics, pass characteristics, and classification accuracy, which will be described later.

[0085] Furthermore, the control unit 50 transmits a drive instruction to the coal feeder motor 23 of the coal feeder 20 , for example, to thereby adjust the supply amount (coal supply amount) of the solid fuel that the conveying unit 22 conveys and supplies to the fuel supply unit 17 .

[0086] The control unit 50 then transmits an opening instruction to the air supply unit 30, thereby controlling the openings of the hot air damper 30c and the cold air damper 30d to adjust the flow rate and temperature of the primary air. Specifically, the control unit 50 controls the openings of the hot air damper 30c and the cold air damper 30d so that the flow rate of the primary air supplied into the housing 11 and the temperature of the primary air at the outlet port 19 reach predetermined values ​​set according to the coal supply amount for each type of solid fuel.

[0087] The control unit 50 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. Furthermore, as an example, a series of processes for realizing various functions are stored in a storage medium in the form of a program, and the CPU reads the program into the RAM, and executes information processing / arithmetic processing to realize various functions. Furthermore, the program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or transmitted via a wired or wireless communication means. Computer-readable storage media refers to magnetic disks, optical magnetic disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like. Furthermore, the HDD may be replaced with a solid-state drive (SSD), or the like.

[0088] Next, the boiler 200 that generates steam by burning the pulverized fuel supplied from the solid fuel pulverizing device 100 will be described. The boiler 200 includes a furnace 210 and a burner 220 .

[0089] Burner 220 uses primary air containing pulverized fuel supplied from pulverized fuel supply passage 100b and secondary air supplied by heat exchanger 34, heated by air (outside air) delivered from forced draft fan (FDF) 32, to combust the pulverized fuel, creating a flame. The pulverized fuel is combusted within furnace 210, and the high-temperature combustion gases pass through heat exchangers (not shown) such as the evaporator, superheater, and economizer before being discharged outside boiler 200.

[0090] The combustion gas discharged from boiler 200 flows through flue 36. The combustion gas flowing through flue 36 undergoes denitration treatment through a denitration device 35. The denitration device 35 supplies a reducing agent, such as ammonia or urea water, that reduces nitrogen oxides into the flow path through which the combustion gas flows. The catalytic action of a denitration catalyst installed within the denitration device 35 promotes the reaction between the nitrogen oxides in the combustion gas supplied with the reducing agent and the reducing agent, thereby removing and reducing the nitrogen oxides in the combustion gas. The denitrated combustion gas undergoes heat exchange in a heat exchanger 34, such as an air preheater, with air delivered from a primary air fan 31 and air delivered from a forced draft fan 32. The denitrated combustion gas then passes through an induced draft fan (IDF) 33, undergoes prescribed treatment in environmental equipment (e.g., an electrostatic precipitator and desulfurization device, not shown), and is then directed to a chimney (not shown) and released into the outside air. The air delivered from the primary air fan 31, heated by the combustion gas in the heat exchanger 34, is supplied to the aforementioned hot air flow path 30a.

[0091] After the feed water from the boiler 200 to each heat exchanger is heated in the economizer (not shown in the figure), it is further heated by the evaporator (not shown in the figure) and the superheater (not shown in the figure) to generate high-temperature and high-pressure steam, which is sent to the steam turbine (not shown in the figure) serving as the power generation unit to rotate and drive the steam turbine, thereby rotating and driving the generator (not shown in the figure) connected to the steam turbine to generate electricity, which constitutes the power generation equipment 1.

[0092] Next, the details of the rotary classifier 16 will be described. In the following description, "circumferential direction" and "radial direction" refer to directions with the central axis C as the center.

[0093] like Figure 1 As shown, the rotary classifier 16 is arranged on the upper part of the housing 11. Figure 2 As shown, the rotary classifier 16 rotates around the central axis C extending in the vertical direction. Figure 2 and Figure 3As shown by arrow A1, the rotary classifier 16 rotates clockwise when viewed from above. The rotation direction of the rotary classifier 16 is set to be opposite to the rotation direction of the primary air formed by the rotating blades provided at the air blowing port. The rotary classifier 16 is driven by a motor (not shown). The motor speed is controlled by the control unit 50.

[0094] like Figure 2 As shown, the rotary classifier 16 includes a main body 70 having a hollow, generally inverted conical outer shape. An inner space S1 is formed within the main body 70. The main body 70 integrally comprises a cylindrical shaft 71 that covers the fuel supply unit 17 and extends along the central axis C; an upper end 72 that extends radially from the upper end of the cylindrical shaft 71; and a lower end 73 that extends radially from the lower end of the cylindrical shaft 71. The upper end 72 defines the upper end of the inner space S1. Furthermore, the lower end 73 defines the lower end of the inner space S1.

[0095] Furthermore, the rotary classifier 16 includes a plurality of scrapers 60 provided at the outer periphery of the main body 70. Each scraper 60 extends in the vertical direction. Each scraper 60 is a plate-shaped member. The upper end of each scraper 60 is fixed to the upper end portion 72. Furthermore, the lower end of each scraper 60 is fixed to the lower end portion 73. Each scraper 60 is inclined so that the lower end side is closer to the central axis C than the upper end side. A groove is formed at the upper end portion 72 to be aligned with the outlet port 19 (reference Figure 1 ) connected opening 72a.

[0096] like Figure 3 As shown, a plurality of scrapers 60 are arranged in parallel around the central axis C of the rotary classifier 16 at predetermined intervals (equal intervals). Specifically, the scrapers 60 are arranged at predetermined intervals on an imaginary circle V centered on the central axis C. Furthermore, when viewed from above, the scrapers 60 are arranged to be inclined at a predetermined angle relative to the radial direction. Furthermore, a gap is formed between the scrapers 60 adjacent to each other in the circumferential direction. The gap connects the inner space S1 of the plurality of scrapers 60 with the outer space S2 of the scraper 60. The pulverized fuel is introduced into each scraper 60 together with the primary air flowing from the radial outside to the inside.

[0097] Each blade 60 has a collision surface 61 as a surface on the front side in the rotation direction and a back surface 65 as a surface on the rear side in the rotation direction.

[0098] like Figure 3As shown, the pulverized fuel, including finely pulverized fuel B2 and coarsely pulverized fuel B1, collides with collision surface 61. A radial outward force (centrifugal force and collision force, hereinafter referred to as the outward force) indicated by arrow A2 and a radial inward force (centripetal force generated by the flow of primary air, hereinafter referred to as the inward force) indicated by arrow A3 act on the pulverized fuel colliding with collision surface 61. Because coarsely pulverized fuel B1 is heavy, the centrifugal force exerts a strong outward force A2 on the pulverized fuel B1 colliding with collision surface 61. As a result, the coarsely pulverized fuel B1 overcomes the inward force A3 and, as indicated by arrow A4, is ejected toward the outside of scraper 60 (toward outer space S2). On the other hand, because finely pulverized fuel B2 is light, the centrifugal force acting on the pulverized fuel B2 colliding with collision surface 61 is relatively weak. Thus, among the forces acting on the pulverized fuel B2 , the inward force indicated by the arrow A3 becomes dominant, and thus the pulverized fuel B2 is guided to the inside of the scraper 60 (toward the inner space S1 ) as indicated by the arrow A5 .

[0099] The rotary classifier 16 classifies the coarse pulverized fuel B1 and the fine pulverized fuel B2 based on such a principle.

[0100] [Cross-sectional shape of the scraper blade]

[0101] Next, the shape of each scraper blade 60 will be described using a vertical cross-sectional shape (a cross-sectional shape when cut on a plane perpendicular to the vertical direction (a horizontal plane)). In the following description, when simply referred to as a "cross-sectional shape," this refers to the cross-sectional shape of the scraper blade when cut on a horizontal plane (a blade cross-sectional shape).

[0102] Each blade 60 is formed to have the same shape in the vertical direction. That is, the cross-sectional shape of each blade 60 is the same at any position in the vertical direction.

[0103] like Figure 4 As shown, as described above, each blade 60 has the collision surface 61 and the back surface 65 which is the surface on the opposite side to the collision surface 61 .

[0104] The back surface 65 is set to be a flat surface.

[0105] The collision surface 61 includes a curved surface 62 disposed radially outward and a flat surface 63 disposed radially inward of the curved surface 62. The curved surface 62 and the flat surface 63 are smoothly connected at a boundary point D. The boundary point D is located approximately at the center of the collision surface 61 in the radial direction.

[0106] The curved surface 62 is provided at the radially outer side of the boundary point D. The curved surface 62 is curved so as to be oriented in the rotation direction (reference Figure 3The curved surface 62 is curved so that its thickness decreases as it moves radially outward from the boundary point D. Specifically, the curved surface 62 is bent so that the thickness becomes zero at the radially outer end of the scraper 60. That is, the curved surface 62 and the back surface 65 are connected at the radially outer end of the scraper 60. Furthermore, this configuration creates an acute angle at the radially outer end of the scraper 60. Therefore, the radially outer end of the scraper 60 can be covered with a cover or the like to prevent cuts.

[0107] Furthermore, the angle (hereinafter referred to as "inclination angle θ") formed by the tangent line L1 of the imaginary circle V and the perpendicular line L2 to the collision surface 61 is larger on the radially outer side of the curved surface 62 than on the radially inner side. Figure 4 As shown, the curved surface 62 is curved such that the inclination angle θ3 at a point P3 located radially outward from the point P2 is larger than the inclination angle θ2 at the point P2 .

[0108] In addition, the curved surface shape of the curved surface 62 is determined according to the required grading characteristics. For example, as described in the present embodiment, the curved surface shape of the curved surface 62 is preferably a shape in which the radius of curvature is largest at the connection portion with the flat surface 63, and the radius of curvature decreases as it moves away from the flat surface 63 (as it moves radially outward). However, the curved surface 62 may also be set to a constant curvature. Furthermore, for example, it may be an arc shape, a shape that is a portion of an ellipse, or a parabola shape. In addition, the grading characteristics are an indicator of the difficulty of the crushed fuel passing through (ejecting toward the outer peripheral side of the scraper 60), and the value becomes larger as it is more difficult to pass through.

[0109] The flat surface 63 is inclined at a predetermined angle with respect to the radial direction. Furthermore, the inclination angle θ1 of the flat surface 63 is smaller than the inclination angle of the curved surface 62 (for example, the inclination angle θ2 and the inclination angle θ3).

[0110] The imaginary circle V is an imaginary circle centered on the central axis C and is also a rotation locus of an arbitrary point within the blade cross section of the wiper blade 60 .

[0111] [Processing method of scraper blade]

[0112] Next, a method for processing the blade 60 will be described.

[0113] The method for processing the blade 60 is not particularly limited. For example, the blade 60 may be processed to have a curved surface on the collision surface 61 by cutting a flat plate-shaped material.

[0114] Furthermore, by appropriately selecting the material and hardness of the flat blade in consideration of the differences in wear rates depending on the location of the blade, a curved surface can be formed on the impact surface of the blade due to wear during use of the rotary classifier 16. Specifically, if the blade contacts the pulverized particles more frequently and wears faster toward the radially outer periphery, for example, if the surface hardness of the impact surface of the flat blade is made uniform, the thickness reduction due to wear will increase toward the radially outer periphery, thereby forming a curved surface as the blade is used.

[0115] Furthermore, it is preferable to appropriately select the material and hardness of the scraper 60 so that the curved surface is maintained due to wear of the scraper 60 during use of the rotary classifier 16. This can reduce the frequency of maintenance of the scraper 60.

[0116] [Grading performance]

[0117] Next, the classification performance of the rotary classifier will be described.

[0118] First, use Figures 15 to 21 The classification performance of the rotary classifier 16 including the flat blade 60X according to the comparative example will be described. The flat blade 60X is inclined at a predetermined angle relative to the radial direction when viewed in a horizontal cross section.

[0119] First, find Figure 17 The pass characteristics of the flat blade 60X at various radial positions of the blade 60X shown in G4 are shown. The pass characteristics are an indicator of how easily the pulverized fuel passes through the classifier (the value increases as it passes more easily on the inner circumference of the blade 60), and will be described in detail later.

[0120] Figure 17 The relationship between each radial position of the blade 60X (horizontal axis), the outward force acting on the pulverized fuel (left vertical axis), and the passing characteristics of the pulverized fuel (right vertical axis) is shown. Figure 17 The horizontal axis of the graph represents the distance from the inlet (radial outer end) of the scraper 60X. Specifically, the horizontal axis represents the radial position of the scraper 60X, with the left end representing the radial outer end of the scraper 60X (the outer end on the side of the outer space S2 of the scraper 60X), and the right end representing the radial inner end of the scraper 60X (the outer end on the side of the inner space S1 of the scraper 60X). Furthermore, the outward forces acting on the pulverized fuel include those generated by centrifugal force and those generated by collision. The pass-through characteristic has a positive correlation with the inward force acting on the pulverized fuel, that is, a negative correlation with the outward force (centrifugal force + collision force).

[0121] Figure 17 G1 represents the outward force F3 (refer to Figure 16). Also, G2 represents the outward force F5 (refer to Figure 16 The outward force F3 acting on the pulverized fuel by the collision and the outward force F5 generated by the centrifugal force acting on the pulverized fuel are obtained as follows.

[0122] like Figure 15 As shown, when the pulverized fuel including the pulverized fuel B2 and the coarse pulverized fuel B1 collides with the flat blade 60X, the coarse pulverized fuel B1 is ejected toward the outside of the blade 60X (toward the outer space S2) as indicated by arrow A6. Meanwhile, the pulverized fuel B2 is ejected toward the inside of the blade 60X (toward the inner space S1) as indicated by arrow A7.

[0123] like Figure 16 As shown, arrow F1 represents the force of the pulverized fuel colliding with the rotating scraper 60X. This force, indicated by arrow F1, can be decomposed into a force acting perpendicularly to the collision surface of scraper 60X (arrow F2) and a force acting parallel to the collision surface of scraper 60X (arrow F3). The perpendicular force is offset by the vertical resistance (arrow F4) from scraper 60X. Since the offsetting force does not act on the parallel force, the outward force F3 of scraper 60X acts on the colliding pulverized fuel. In other words, the outward force F3 generated by the collision acts.

[0124] In addition, Figure 16 In FIG. 5 , arrow F5 represents the radial outward force generated by centrifugal force along the collision surface of blade 60X, and arrow F6 represents the radial inward force generated by the flow of primary air along the collision surface of blade 60X. The outward force F3 is obtained by the following formula (1).

[0125] [Formula 1]

[0126] F3=F1×sinθ……(1)

[0127] Wherein, F1: the force of the collision between the pulverized fuel and the rotating scraper 60X

[0128] θ: Angle formed by the direction in which the force of the pulverized fuel colliding with the rotating scraper 60X acts (see arrow F1) and the direction of the force acting in the vertical direction (see arrow F2)

[0129] In addition, under actual machine usage conditions, the friction force generated between the pulverized fuel and the scraper 60X is smaller than other forces and is therefore neglected in the calculation.

[0130] Thus, the larger the inclination of the scraper 60X relative to the radial direction, the more the outward force F5 of the scraper 60X acts. Moreover, the scraper 60X is flat. Therefore, in the scraper 60X, the angle θ is constant regardless of the radial position. Figure 17 As shown in G1, the outward force F5 is constant regardless of the radial position of the scraper 60X.

[0131] Then, the pulverized fuel that collides with the scraper blade 60X is subjected to a centrifugal force F5 by the scraper blade 60X. The centrifugal force F5 is obtained by the following formula (2).

[0132] [Formula 2]

[0133] F5=m×r×ω 2 ……(2)

[0134] Where, m: mass of crushed fuel

[0135] r: rotation radius of the collision position

[0136] ω: angular velocity of the scraper 60X

[0137] Therefore, the centrifugal force F5 acting on the pulverized fuel colliding with the scraper blade 60X at the same rotation speed is determined by the mass of the pulverized fuel and the rotation radius of the collision position.

[0138] Furthermore, the mass of the pulverized fuel B2 is small. Furthermore, as will be described later, the pulverized fuel B2 collides with the radially inner side of the scraper blade 60X, that is, with a portion having a small rotation radius. This reduces the centrifugal force F5 acting on the pulverized fuel B2. Consequently, when the radially inward force F6 generated by the primary air flow overcomes the centrifugal force F5, the pulverized fuel B2 moves radially inward of the scraper blade 60X.

[0139] On the other hand, the pulverized fuel B1 has a large mass. Furthermore, as will be described later, the pulverized fuel B1 collides with the radially outer side of the scraper blade 60X, that is, with a portion having a large rotation radius. This increases the centrifugal force F5 acting on the pulverized fuel B1. Consequently, when the centrifugal force F5 overcomes the radially inward force F6 generated by the primary air flow, the pulverized fuel B1 is ejected radially outward from the scraper blade 60X.

[0140] From the above content, such as Figure 17 As shown in G2, the force generated by the centrifugal force F5 becomes a linear function and thus becomes a straight line inclined downward to the right.

[0141] and, Figure 17 G3 represents the outward force based on the sum of the outward force F5 generated by the centrifugal force and the outward force F3 generated by the collision. As described above, if the scraper 60X is flat, the outward force F3 generated by the collision is constant. Figure 17As shown in G3, the outward force (centrifugal force + collision force) becomes a straight line inclined downward to the right.

[0142] Figure 17 The pass characteristic shown in G4 is inversely proportional (negatively correlated) to the outward force (centrifugal force + collision force). Therefore, as shown in G4, the pass characteristic becomes a straight line that slopes upward to the right, opposite to the slope of G3, which represents the outward force (centrifugal force + collision force).

[0143] In this manner, the passing characteristics of the flat blade 60X are obtained.

[0144] Here, that is, Figure 17 The passing characteristics shown in the figure represent the mass of a single pulverized fuel that can pass through. If the density of the pulverized fuel is set to be constant, it represents the volume of the pulverized fuel, that is, the size of the pulverized fuel. Therefore, if Figure 18A As shown in G5a, the passing characteristics are proportional to the size of the pulverized fuel passing through (positive correlation). Figure 17 As shown in G4 of FIG. 1 , the passing characteristic is proportional to the distance from the outer end side of the scraper 60X. Therefore, as Figure 18B As shown in G5b, the size of the pulverized fuel that passes through is also proportional to the distance from the outer end side of the scraper 60X. Figure 18A Graph showing the relationship between the size of the pulverized fuel passing through the blade 60X and the passing characteristics. Figure 18B Graph showing the relationship between the size of the pulverized fuel passing through the scraper 60X and the distance from the inlet of the scraper 60X.

[0145] Next, use Figure 19 and Figure 20 , the classification effect caused by the flow of primary air is explained.

[0146] First, the pulverized fuel is pulverized on the pulverizing table 12 of the mill 10 and transported to the rotary classifier 16 by the primary air (transport gas) blown from the periphery of the pulverizing table 12. As described above, at this time, the air flow E (primary air flow) is a flow that rises while rotating inside the housing 11, as shown in FIG. Figure 19 As shown, the scraper 60X reaches the rotary classifier 16 from the outer peripheral side of the scraper blade by rotating in the reverse direction relative to the rotation direction A1 of the scraper blade 60X.

[0147] like Figure 19 As shown, the airflow E reaching the side of the scraper 60X sharply bends its path toward the path between the adjacent scrapers 60X. At this time, the path of the light-weight and low-inertia fine powder fuel B2 is easily changed along with the airflow E. On the other hand, the path of the heavy-weight and high-inertia coarse powder fuel B1 is not easily changed. Based on this characteristic, as Figure 19As shown, the fine powder fuel B2 passes through the inner peripheral side of the curve of the air flow, and the coarse powder fuel B1 passes through the outer peripheral side of the curve of the air flow, thereby performing rough classification based on the air flow. As a result of the rough classification, the fine powder fuel B2 collides with the outlet side (radially inner side) of the scraper 60X, and the ratio of the coarse powder fuel B1 colliding with the inlet side (radially outer side) of the scraper 60X becomes larger. The distribution of the pulverized fuel at this time roughly depends on the inertial force of the pulverized fuel. That is, according to the relationship of F (force) = m (mass) · a (acceleration), when receiving equal fluid force from the air flow of the primary air, the light particles (fine powder fuel B2) generate a large acceleration. In addition, the moving distance of an object to which a constant acceleration is applied is X = a (acceleration) · t (time) 2 , so if Figure 20 As shown, the distribution of particles colliding with the blade 60X is a curve-like distribution close to a quadratic function. Figure 20 This is a graph showing the relationship between the particle size of the pulverized fuel that collides with the scraper 60X and the distance from the inlet of the scraper 60X. However, the starting point at which the pulverized fuel begins to change direction toward the scraper 60X depends on the flight trajectory of the particles, so according to this change, the distribution characteristics become a wide distribution with a certain degree of width. In this way, the size of the pulverized fuel particles that collide with each position in the radial direction of the scraper 60X (hereinafter referred to as "collision particle size distribution") becomes Figure 20 The range shown by the hatching. In addition, in the above description, the case of collision with the flat blade 60X is described, but the size of the pulverized fuel particles colliding with the blade does not change depending on the shape of the blade. Therefore, for example, even in the case of collision with the blade 60 provided with the curved surface 62 described in this embodiment, the collision particle size distribution becomes Figure 20 The distribution shown.

[0148] Next, use Figure 21 , the overall passing characteristics of the rotary classifier 16 having the flat blade 60X (i.e., the classification performance of the rotary classifier 16) are described. Figure 21 In the graph, the left vertical axis represents the particle size of the pulverized fuel that collides with the scraper 60X, and the right vertical axis represents the particle size of the pulverized fuel that passes through the scraper 60X. The horizontal axis represents the distance from the inlet (outer end) of the scraper 60X.

[0149] The overall passing characteristics of the rotary classifier 16 in this description are given by Figure 18B The size of the pulverized fuel by the scraper 60X shown in G5b and Figure 20 The pulverized fuel distribution shown is derived. Figure 21In FIG. 1 , the particle size of the pulverized fuel at which G5b, which indicates the size of the pulverized fuel passing through the scraper 60X, intersects the upper edge line of the collision particle size distribution is defined as the target particle size of the rotary classifier 16. The target particle size is the upper limit of the particle size of the pulverized fuel to be discharged from the mill 10 (supplied to the burner 220 of the boiler 200) after passing through the rotary classifier 16.

[0150] exist Figure 21 The area below the upper edge of the collision particle size distribution and G5b, which represents the size of the pulverized fuel passing through the scraper 60X, is the area of ​​the pulverized fuel that passes through the rotary classifier 16. Specifically, the area below the dashed line G6 is the area of ​​the pulverized fuel that passes through the rotary classifier 16. The scraper inlet side (outer end), where there is more coarse pulverized fuel, has a relatively low flow rate (i.e., it is difficult for fuel to pass through). Conversely, the scraper outlet side (inner end), where there is more fine pulverized fuel, has a relatively high flow rate (i.e., it is easy for fuel to pass through). This prevents the coarse pulverized fuel from passing through, while allowing the fine pulverized fuel to pass through. This effectively achieves the classification effect.

[0151] Next, use Figures 22 to 24 The classification performance of the rotary classifier 16 having the folded plate-shaped scraper 60Y according to the comparative example will be described. Figure 22 As shown, the folded plate-shaped scraper blade 60Y is connected so that the outer plate-shaped portion 60Ya and the inner plate-shaped portion 60Yb form an angled inflection point H. The scraper blade 60Y has different inclination angles relative to the radial direction at the outer portion 60Ya and the inner portion 60Yb. Furthermore, the inclination angle of the outer portion 60Ya of the scraper blade 60Y is larger than that of the inner portion 60Yb. This description uses an example in which the inclination angle of the inner portion 60Yb is the same as that of the scraper blade 60X described above.

[0152] like Figure 22 As shown, when the pulverized fuel including the finely pulverized fuel B2 and the coarsely pulverized fuel B1 collides with the folded plate-shaped scraper 60Y, the coarsely pulverized fuel B1 is also ejected toward the outside of the scraper 60Y (toward the outer space S2) as indicated by arrow A8. Meanwhile, the finely pulverized fuel B2 is ejected toward the inside of the scraper 60Y (toward the inner space S1) as indicated by arrow A9.

[0153] The scraper 60Y has different inclination angles relative to the radial direction at the outer portion 60Ya and the inner portion 60Yb. This means that the direction of the collision force of the pulverized fuel colliding with the scraper 60Y is different. Therefore, the outward force (the force calculated by the above formula (1)) acting on the pulverized fuel colliding with the inner portion 60Yb with a smaller inclination angle is different. Figure 16 The F3) is small, and the outward force acting on the particles colliding with the outer portion 60Ya with a large inclination angle is large.

[0154] Therefore, if Figure 23 As shown in G7, the outward force generated by the collision force in the outer portion 60Ya of the scraper 60Y becomes larger, and the outward force generated by the collision force in the inner portion 60Yb becomes smaller. Figure 17 Likewise, Figure 23 G2 represents the outward force generated by the centrifugal force acting on the pulverized fuel. Furthermore, G8 represents the outward force based on the sum of the outward force generated by the centrifugal force and the outward force generated by the collision force. As shown in G7, the outward force generated by the collision force changes significantly at the inflection point H, so G8 also changes significantly at the inflection point H. In the following description, the portion where the outward force changes significantly is referred to as the "portion with a step." Furthermore, Figure 23 The passing characteristic shown in G9 is inversely proportional to the outward force (centrifugal force + collision force) (negative correlation). Figure 23 The hatched area K1 indicates a region where the passage characteristics are reduced compared to the flat blade 60X. This indicates that the passage characteristics (inward force) are reduced in the outer portion 60Ya, where the pulverized fuel B1 is more likely to collide, thereby suppressing the passage of the pulverized fuel B1 compared to the flat blade 60X.

[0155] Next, use Figure 24 The overall passing characteristics of the rotary classifier 16 having the folded plate-shaped scraper 60Y (i.e., the classification performance of the rotary classifier 16) are described. The overall passing characteristics of the rotary classifier 16 in this description are based on Figure 23 G9 represents the size of the pulverized fuel by the scraper 60Y, G10 and Figure 20 The collision size distribution shown is derived.

[0156] exist Figure 24 In the figure, the area below G11, indicated by the dotted line, is the area where the pulverized fuel passes through the rotary classifier 16. As indicated by the hatched line K2, the passage characteristics of the outer portion 60Ya are reduced compared to the case where a flat blade 60X is used. Furthermore, the passage characteristics in areas with large particle sizes, particularly those with a very low proportion of particles below the target particle size, are extremely reduced. This prevents the passage of coarse pulverized fuel, improving classification performance.

[0157] On the other hand, in the region of hatched line K3, although within the range of the collision particle size distribution and below the target particle size, the particles are still ejected outward by the scraper blade 60Y. Therefore, it can be seen that the classification performance is reduced compared to the case where the flat scraper blade 60X is used (the pulverized fuel that should pass without being classified is ejected outward).

[0158] Furthermore, the classification characteristics include a stepped portion. Whether the pulverized fuel in the particle size range J corresponding to the stepped portion passes or fails to pass through the scraper 60Y depends on the impact position. Therefore, whether or not the pulverized fuel is classified is random depending on the particle size. Consequently, a portion of the pulverized fuel that should pass through the rotary classifier 16 is ejected by the scraper 60Y, resulting in a decrease in classification performance.

[0159] The ejected finely divided fuel flows back to the pulverizing table 12 and is pulverized again. This further pulverization of the finely divided fuel causes a problem: not only is pulverization power wasted, but sliding vibrations are also likely to occur in the mill 10 due to the pulverizing rollers 13 sliding on the pulverizing table 12 as the pulverizing rollers 13 act as a solid lubricant.

[0160] Next, use Figure 5 and Figure 6 The classification performance of the rotary classifier 16 according to this embodiment including the scraper 60 having the curved surface 62 will be described. In this description, an example in which the inclination angle of the flat surface 63 is the same as that of the scraper 60X described above will be described.

[0161] In the curved surface 62, the inclination angle is considered to change continuously. Figure 5 As shown in G20, the outward force generated by the collision force also changes smoothly. Specifically, in the curved surface 62, the inclination angle is larger on the radially outer side than on the radially inner side. Therefore, the outward force generated by the collision force increases as it moves toward the radially outer side. Furthermore, G21, which represents the outward force based on the sum of the outward force generated by the centrifugal force and the outward force generated by the collision force, also changes smoothly in such a manner that the outward force increases as it moves toward the radially outer side. In addition, Figure 17 Likewise, Figure 5 G2 represents the outward force generated by the centrifugal force acting on the pulverized fuel. Figure 5 The passing characteristics shown in G22 are inversely proportional (negatively correlated) to the outward force (centrifugal force + collision force). Therefore, like G21, G22 also changes smoothly. Figure 5 The hatched K4 indicates a region where the passage characteristics can be reduced compared to the flat blade 60X. Thus, it can be seen that the passage characteristics (inward force) can be reduced on the radially outer side where the pulverized fuel B1 is likely to collide, thereby suppressing the passage of the pulverized fuel B1 compared to the flat blade 60X.

[0162] Next, use Figure 6The whole through-characteristics of the rotary classifier 16 having the folded plate-shaped scraper 60 according to this embodiment (i.e., the classification performance of the rotary classifier 16) are described. The whole through-characteristics of the rotary classifier 16 in this description are based on Figure 5 G22 represents the size of the pulverized fuel by the scraper 60, G23 and Figure 20 The collision size distribution shown is derived.

[0163] exist Figure 6 In the figure, the area below the dashed line G24 represents the area of ​​pulverized fuel that passes through the rotary classifier 16. As indicated by hatched lines K5 and K6, the passage characteristics on the curved surface 62 are reduced compared to the case where a flat blade 60X is used. Furthermore, as indicated by hatched line K6, the passage characteristics on the curved surface 62 are reduced compared to the case where a folded blade 60Y is used. Furthermore, the passage characteristics in areas with large particle sizes, particularly areas where the proportion of particles below the target particle size is extremely low, are extremely reduced. This further reduces the passage of coarse pulverized fuel, improving classification performance.

[0164] By suppressing the passage of pulverized fuel in this manner, the supply of pulverized fuel with a particle size larger than the target diameter to burner 220 can be suppressed. This reduces the amount of pulverized fuel (unburned pulverized fuel) that remains unburned in burner 220, and the amount of unburned fuel in the ash discharged from boiler 200 can be reduced. Furthermore, by reducing the amount of unburned fuel in the ash, the amount of air supplied to boiler 200 can be reduced (low air ratio combustion), and the generation of nitrogen oxides can be suppressed. Consequently, the environmental burden can be reduced. Furthermore, the amount of reducing agent (ammonia, etc.) used in denitrification device 35 can be reduced, reducing operating costs.

[0165] On the other hand, the area of ​​the hatched line K7 is within the collision particle size distribution range and is below the target particle size, but is still ejected toward the outer periphery by the scraper 60Y. Figure 24 Compared with the hatched line K3), the region where the classification performance is reduced can be reduced. Thus, the reduction in classification performance can be suppressed.

[0166] By suppressing the recirculation of the pulverized fuel B2, the re-grinding of the pulverized fuel B2 can be suppressed. This reduces the grinding power of the mill 10. Furthermore, the sliding vibration of the mill 10 caused by the recirculated pulverized fuel acting as a lubricant can be reduced.

[0167] Furthermore, by using a structure that changes the inclination angle of the curved surface 62, the stepped portion that occurs when using the folded plate-shaped blade 60Y is eliminated. This eliminates regions where classification is random depending on the particle size, thereby improving classification performance.

[0168] In this embodiment, in addition to improving the above-mentioned classification performance, the following effects are also achieved.

[0169] In this embodiment, a curved surface 62 is formed on the radially outer side of the scraper 60. With this type of scraper blade 60 with a curved front end, even if the scraper 60 wears due to collision with pulverized fuel during use of the rotary classifier 16, its curved surface shape is substantially maintained. In other words, the scraper blade 60 with a curved front end maintains its self-correcting property, whereby the radial length of the scraper 60 decreases as it wears. This is because larger and heavier particles, which tend to collide with the scraper 60 in greater numbers and at higher speeds, accelerate wear as they move toward the outer side of the scraper 60. Therefore, by appropriately designing the material and hardness of the scraper 60, the curved surface 62 of the scraper 60 can be maintained over a long period of time, ensuring sustained performance.

[0170] In this embodiment, the collision surface 61 includes a curved surface 62 and a flat surface 63. The flat surface 63 is easier to manufacture than the curved surface 62, so the blade 60 can be manufactured more easily than when the entire collision surface 61 is formed as the curved surface 62.

[0171] Furthermore, generally, the further inwardly the collision surface 61 is radially, the greater the influence of the primary air force (i.e., the force directed from the radially outer side of the scraper 60 toward the inner side), thus reducing the influence of the outward force generated by the collision force of the pulverized fuel. In this embodiment, a flat surface 63 is formed radially inwardly. This reduces degradation in classification performance compared to a case where the flat surface 63 is formed radially outwardly.

[0172] In addition, the boundary point D as the boundary between the curved surface 62 and the flat surface 63 can be compared to Figure 6 The point L where G23, which represents the size of the pulverized fuel passing through the scraper 60, intersects the upper edge line of the collision particle size distribution is located further radially inward. This configuration allows the entire surface of the flat surface 63 to be used as an area where the outward force generated by the collision force is less affected, thereby further suppressing the degradation of classification performance caused by the formation of the flat surface 63.

[0173] Furthermore, in this embodiment, the circumferential length (length in the thickness direction) of the scraper blade 60 decreases radially outward. This allows the scraper blade 60 to be thinner, making it less likely that tools, etc., will interfere with adjacent scrapers during installation. This makes installation of the scraper blade 60 easier.

[0174] The present invention is not limited to the above-described embodiment, and can be modified appropriately without departing from the spirit of the present invention.

[0175] For example, in the above-mentioned embodiment, the mill of the present invention is used. However, the solid fuel may be biomass fuel or PC (petroleum coke) fuel produced during petroleum refining, or a combination of these fuels may be used.

[0176] Furthermore, in the above embodiment, an example in which the classifier of the present invention is applied to a mill for crushing solid fuel has been described, but the present invention is not limited thereto. For example, the classifier of the present invention may be applied to a pulverizer for crushing ore.

[0177] Furthermore, the radial length of the blade 60 decreases with wear. Therefore, it is preferable to set a replacement criterion based on the radial length. Accordingly, a detection mechanism for detecting the radial length can be provided on the blade 60 and used as a wear detection sensor.

[0178] The scraper blade 60 is preferably detachably secured to the main body 70 by bolts or the like so that it can be replaced in the event of wear. However, if the scraper blade 60 is made of a material with sufficient wear resistance, it may also be secured by welding or the like. The mounting surface and bolt support surface for mounting to the main body 70 are preferably provided on the flat surface 63 of the scraper blade 60, but the mounting surface or the like may also be provided on the curved surface 62. If the mounting surface or the like is provided on the curved surface 62, a countersink or the like may be provided, or a washer or the like that matches the curvature may be used to form the support surface.

[0179] [Modification of the Scraper Blade]

[0180] Furthermore, the present invention is not limited to the above-described shape of the blade 60. Modifications of the blade 60 will be described below with reference to the accompanying drawings.

[0181] [Variant 1]

[0182] like Figure 7 As shown, the scraper blade can be manufactured by stacking multiple thin plates in the thickness direction. The scraper blade 60A is formed by stacking thin plates (60Aa, 60Ab, and 60Ac) of different radial lengths. Each plate can be formed of the same material or different materials. When formed of different materials, the plates can be arranged so that the plates are formed of a material with high wear resistance as they move from the collision surface 61 side toward the back surface 65 side. In this way, the self-shaping properties can be more appropriately utilized.

[0183] [Variant 2]

[0184] And, as Figure 8As shown, the circumferential length (plate thickness) of the scraper blade can be constant throughout the entire radial region. Regarding the scraper blade 60B, the curved surface 62 is formed on the collision surface 61 by bending the flat scraper blade. Thus, in this modified example, the scraper blade 60B having the curved surface can be formed simply by bending, making it easy to manufacture the scraper blade 60B.

[0185] Furthermore, the circumferential length (plate thickness) of the blade 60B is constant throughout the entire radial region, and thus the length that can tolerate wear is increased throughout the entire radial region, thereby improving the durability of the blade 60B.

[0186] [Variant 3]

[0187] And, as Figure 9 As shown, a plurality of recesses 80 may be formed on the curved surface 62 of the blade. The blade 60C has a constant circumferential length (plate thickness) throughout the entire radial region, and has a plurality of recesses 80 formed on the curved surface 62. Examples of the recesses 80 include depressions.

[0188] The blade 60C has a self-lining structure formed by a plurality of recesses 80. The recesses 80 are formed to have a radius of curvature sufficiently smaller than the radius of curvature of the curved surface 62. Specifically, the recesses 80 are sized to not affect the overall shape of the curved surface 62. Specifically, for example, if the curvature radius R of the curved surface 62 is 100, or if the curvature radius R of the recesses 80 is approximately 10 or less, the overall shape of the curved surface 62 is not affected.

[0189] In the self-lining structure, recessed portion 80 is formed in curved surface 62, allowing pulverized fuel to enter recessed portion 80. This allows the pulverized fuel to cover the surface of curved surface 62. The pulverized fuel covering the surface of curved surface 62 prevents the circulating pulverized fuel from contacting curved surface 62, thereby reducing wear on curved surface 62.

[0190] In addition, even if a corrugated shape is formed instead of the recessed portion 80 , the same effect can be obtained.

[0191] Furthermore, the recessed portion 80 or the corrugated shape is not limited to the curved surface 62 , and may be provided on the flat surface 63 . By providing the recessed portion 80 or the corrugated shape on the collision surface 61 , wear can be suppressed.

[0192] [Variant 4]

[0193] Furthermore, in the above embodiment, the scraper 60 is described as having the same shape in the vertical direction, but the present invention is not limited thereto. Figure 10 As shown in FIG. 1 , the cross-sectional shape of the scraper blade 60D can be smoothly changed in the up-down direction. Figure 10 As shown, the cross-sectional shape of the upper portion of the scraper 60D can be (refer to Figure 11 ) and the cross-sectional shape of the lower part (reference Figure 12 ) different shapes. Specifically, Figure 10 In the example shown, the cross-sectional shape of the upper portion of the scraper 60D is smaller in curved surface than the cross-sectional shape of the lower portion. Figure 2 As shown in FIG. 1 , the scraper 60D is inclined so that the upper portion is farther from the central axis C than the lower portion, and thus the centrifugal force R1 (refer to FIG. Figure 2 ) is greater than the centrifugal force R2 acting on the lower part (reference Figure 2 ). In the upper portion where the centrifugal force is strong, even if the curved surface 62 is reduced to prevent the fuel from being ejected radially outward, the pulverized fuel can be ejected radially outward sufficiently. On the other hand, in the lower portion where the centrifugal force is weak, the curved surface 62 is enlarged to facilitate the ejection radially outward, and the pulverized fuel can be ejected radially outward sufficiently. Figure 10 In the illustrated example, even when the scraper blade 60D is inclined with respect to the vertical direction, the manner in which the pulverized fuel is ejected radially outward can be made uniform in the vertical direction.

[0194] In addition, if Figure 13 As shown in FIG. 1 , in the case of the rotary classifier 16A in which the scraper 60E extends in the vertical direction (ie, in the case of no inclination), the centrifugal force R3 acting on the scraper 60E does not change in the vertical direction, so as shown in FIG. Figure 14 As shown, the same shape can be used in the vertical direction. By making the same shape in the vertical direction, a simple structure can be made, and thus it can be easily manufactured.

[0195] Furthermore, the upper and lower ends of the scraper blade, which are fixed to the upper end 72 and lower end 73 of the main body 70, can be rectangular in cross-section, rather than having curved surfaces. This allows for a larger surface area for fixing the scraper blade and the main body 70 than with curved surfaces. This allows for a secure fixation of the scraper blade.

[0196] Furthermore, the curved surface 62 may not be a complete curved surface, but may be a combination of planes with small angle differences, or thin layers may be combined into a stepped shape to digitally form a curved surface. Furthermore, a plane may be inserted into a portion of the front end or midway of the curved surface 62 according to the desired graded performance.

[0197] The classifier, the power generation equipment, and the operating method of the classifier described in the above-described embodiments can be understood, for example, as follows.

[0198] A classifier according to one embodiment of the present invention is a classifier (16) for classifying particles introduced together with a conveying gas into particles larger than a specified particle size and particles smaller than a specified particle size, the classifier comprising: a plurality of scrapers (60) extending in an up-down direction, arranged circumferentially on an imaginary circle (V) centered on a central axis (C) extending in the up-down direction, and introducing the particles together with the conveying gas from the radial outside toward the inside, the scraper (60) having a collision surface (61), in which the introduced particles collide, and the particles larger than the specified particle size among the collided particles are ejected in the radial outward direction, and the particles smaller than the specified particle size are ejected in the radial inward direction, and in the collision surface (61), the angle formed by the tangent of the imaginary circle (V) and the perpendicular to the collision surface (61) is larger on the radial outside than on the radial inside.

[0199] Generally, the scrapers of a classifier tend to collide with larger-diameter pulverized solid fuel (hereinafter referred to as "pulverized fuel") more easily toward the radially outward direction, and with smaller-diameter pulverized fuel more easily toward the radially inward direction. Furthermore, the larger the angle formed between the tangent to the imaginary circle and the perpendicular to the collision surface (hereinafter referred to as the "inclination angle"), the more strongly the pulverized fuel is ejected radially outward.

[0200] In the above-described structure, the collision surface of the scraper has a larger inclination angle on the radially outer side than on the radially inner side. That is, on the radially outer side, where pulverized fuel with large particle sizes is more likely to collide, the scraper has a shape that has a stronger force ejecting the pulverized fuel radially outward. Therefore, pulverized fuel with large particle sizes can be strongly ejected radially outward. On the other hand, the collision surface of the scraper has a smaller inclination angle on the radially inner side than on the radially outer side. That is, on the radially inner side, where pulverized fuel with small particle sizes is more likely to collide, the scraper has a shape that has a weaker force ejecting the pulverized fuel radially outward. Therefore, pulverized fuel with small particle sizes is easily introduced radially inward along with the transport gas flowing from the radially outer side toward the inner side. Thus, pulverized fuel with small particle sizes can be ejected radially inward.

[0201] In this manner, the pulverized fuel having a large particle size can be easily ejected radially outward, and the pulverized fuel having a small particle size can be easily ejected radially inward, thereby improving the classification performance of the classifier.

[0202] Furthermore, in a classifier according to one embodiment of the present invention, the collision surface (61) has a curved surface (62) that is curved in a protruding manner, and in the curved surface (62), the angle formed by the tangent of the imaginary circle (V) and the perpendicular to the collision surface (61) is larger on the radially outer side than on the radially inner side.

[0203] For example, if the scraper blade is shaped like a folded plate, consisting of a flat outer portion and an inner portion connected at different inclination angles, the location at which the pulverized fuel enters determines whether the pulverized fuel collides with the outer portion and is ejected outward from the scraper blade, or collides with the inner portion and is ejected inward from the scraper blade. Therefore, even for pulverized fuel of the same particle size, depending on the entry location, there is a possibility of either classification (ejection outward) or non-classification (ejection outward). This can reduce classification performance.

[0204] On the other hand, in the above structure, the collision surface is curved. This can reduce the area depending on the intrusion position, thereby improving the classification performance.

[0205] Furthermore, in the above-described structure, the curved surface of the scraper blade has a larger inclination angle on the radially outer side than on the radially inner side. That is, on the radially outer side, where pulverized fuel with large particle sizes is more likely to collide, the scraper blade has a shape that has a stronger force ejecting the pulverized fuel radially outward. Therefore, the pulverized fuel with large particle sizes can be strongly ejected radially outward. On the other hand, the curved surface of the scraper blade has a smaller inclination angle on the radially inner side than on the radially outer side. That is, on the radially inner side, where pulverized fuel with small particle sizes is more likely to collide, the scraper blade has a shape that has a weaker force ejecting the pulverized fuel radially outward. Therefore, the pulverized fuel with small particle sizes is easily introduced radially inward along with the transport gas flowing from the radially outer side toward the inner side. Thus, the pulverized fuel with small particle sizes can be ejected radially inward.

[0206] In this manner, the pulverized fuel having a large particle size is easily ejected radially outward, and the pulverized fuel having a small particle size is easily ejected radially inward on the curved surface, thereby improving the classification performance of the classifier.

[0207] The curved surface includes a polygonal surface formed by combining planes with a slight angle difference, and a stepped surface formed by stacking thin layers with their ends offset.

[0208] Furthermore, in the classifier according to one embodiment of the present invention, the collision surface (61) includes the curved surface (62) and a flat surface (63) arranged further inward in the radial direction than the curved surface (62).

[0209] In the above structure, the collision surface has a curved surface and a flat surface. A flat surface is easier to manufacture than a curved surface, so the scraper can be manufactured more easily than when the entire collision surface is a curved surface.

[0210] Furthermore, generally, the influence of the transport gas force (i.e., the force acting from the radially outer side toward the inner side) increases the further inward the collision surface is radially, so the influence of the outward ejection force generated by the tilt angle decreases. In the above-described structure, the flat surface is formed on the radially inner side, thereby suppressing the degradation of classification performance caused by the flat surface.

[0211] Furthermore, in the classifier according to one aspect of the present invention, the scraper (60) has a circumferential length that becomes shorter as it moves toward the radially outer side.

[0212] In the above structure, the circumferential length (length in the thickness direction) of the scraper blade decreases as it moves radially outward. This allows the scraper blade to be thinner, making it less likely that tools, etc., will interfere with adjacent scrapers during installation. This makes installation of the scraper blade easier.

[0213] Furthermore, in the classifier according to one embodiment of the present invention, the scraper (60) has a constant circumferential length throughout the entire radial direction.

[0214] In the above structure, the circumferential length of the scraper blade (the length in the thickness direction) is constant throughout the entire radial area. As a result, for example, by bending a flat scraper blade, a scraper blade with a curved surface can be produced. Therefore, the scraper blade can be easily produced.

[0215] Furthermore, the circumferential length of the blade (the length in the plate thickness direction) is constant throughout the entire radial region, so the length that can be tolerated by wear is increased, thereby improving the durability of the blade.

[0216] Furthermore, in the classifier according to one embodiment of the present invention, a plurality of recessed portions are formed on the collision surface (61).

[0217] In the above structure, multiple recesses are formed on the collision surface. In other words, the multiple recesses form a self-lining structure. As a result, the pulverized fuel enters the recesses and covers the collision surface. The pulverized fuel covering the collision surface prevents contact between the circulating pulverized fuel and the collision surface, thereby reducing wear on the collision surface.

[0218] Furthermore, a power generation device according to one embodiment of the present invention comprises: a classifier (16) as described in any one of the above items; a boiler (200) for burning crushed solid fuel below a specified particle size classified by the classifier (16); and a power generation unit for generating electricity using steam generated by the boiler (200).

[0219] Furthermore, an operating method of a classifier according to one embodiment of the present invention is an operating method of a classifier (16) for classifying particles introduced together with a conveying gas into particles larger than a specified particle size and particles smaller than a specified particle size, wherein the classifier (16) comprises a plurality of scrapers (60), the plurality of scrapers (60) extending in the up-down direction, arranged circumferentially on an imaginary circle (V) centered on a central axis extending in the up-down direction, and the particles are introduced together with the conveying gas from the radial outside toward the inside, the scraper (60) having a collision surface (61), the collision surface In the surface (61), the introduced particles collide, and the particles larger than the specified particle size among the collided particles are ejected in the radial outward direction, and the particles smaller than the specified particle size are ejected in the radial inward direction. In the collision surface (61), the angle formed by the tangent of the imaginary circle (V) and the perpendicular line relative to the collision surface (61) is larger on the radial outward side than on the radial inward side. The operating method of the classifier includes the following steps: the particles are decomposed into the particles larger than the specified particle size and the particles smaller than the specified particle size by the scraper (60).

[0220] Explanation of symbols

[0221] 1- Power generation equipment, 10- Mill, 11- Housing, 12- Crushing table, 13- Crushing roller, 14- Driving unit, 15- Mill motor, 16- Rotary classifier, 17- Fuel supply unit, 18- Classifier motor, 19- Outlet port, 20- Coal feeder, 21- Silo, 22- Conveying unit, 23- Coal feeder motor, 24- Drop pipe, 30- Air supply unit, 30a- Hot air flow path, 30b- Cold air flow path, 30c- Hot air damper, 30d- Cold air damper, 31- Primary air ventilator, 32- Forced air ventilator, 34- Heat exchanger, 35- Degassing Saltpeter device, 36-flue, 40-status detection part, 41-bottom part, 42-ceiling part, 45-journal head, 47-support arm, 48-support shaft, 49-pressing device, 50-control part, 60-scraper, 61-collision surface, 62-curved surface, 63-flat surface, 65-back surface, 70-main body, 71-cylindrical shaft, 72-upper end, 73-lower end, 80-recessed part, 100-solid fuel pulverizing device, 100a-primary air flow path, 100b-fine powder fuel supply flow path, 200-boiler, 210-furnace, 220-burner.

Claims

1. A classifier for classifying particles introduced together with a transport gas into particles larger than a predetermined particle size and particles smaller than a predetermined particle size, the classifier comprising: A plurality of scrapers extending in the vertical direction are arranged circumferentially on an imaginary circle centered on a central axis extending in the vertical direction, and are configured to introduce the particles together with the transport gas flowing from the radially outer side to the radially inner side. The scraper has a collision surface, on which the introduced particles collide, and the particles larger than a predetermined particle size among the collided particles are ejected in the radially outward direction, and the particles smaller than the predetermined particle size are ejected in the radially inward direction. In the collision surface, the angle formed by the tangent line of the imaginary circle and the perpendicular line to the collision surface is larger on the radially outer side than on the radially inner side. The collision surface has a curved surface curved in a protruding manner, In the curved surface, the angle formed by the tangent line of the imaginary circle and the perpendicular line to the collision surface is larger on the radially outer side than on the radially inner side. The blade has a self-correcting property so as to wear while maintaining the curved surface.

2. The classifier according to claim 1, wherein The collision surface includes the curved surface and a flat surface arranged radially inward of the curved surface.

3. The classifier according to claim 1 or 2, wherein: The circumferential length of the scraper blade decreases as it moves toward the radially outer side.

4. The classifier according to claim 1 or 2, wherein: The cross-sectional shape of the upper portion of the blade is smaller than the cross-sectional shape of the lower portion of the blade.

5. The classifier according to claim 1, wherein The scraper blade includes a plurality of plate materials stacked in the circumferential direction.

6. The classifier according to claim 5, wherein: The plurality of plate members are arranged such that the plate members are formed of a material having high wear resistance as they move from the collision surface side toward the back surface side.

7. The classifier according to claim 5 or 6, wherein: The radial lengths of the plurality of plates are different.

8. The classifier according to claim 1 or 2, wherein: The scraper has a constant circumferential length throughout the entire radial region.

9. The classifier according to claim 1 or 2, wherein: A plurality of recessed portions are formed on the collision surface.

10. A power generation device comprising: The classifier according to any one of claims 1 to 9; a boiler for burning the pulverized solid fuel classified by the classifier to a particle size below a predetermined particle size; and The power generation unit generates electricity using the steam generated by the boiler.

11. A method for operating a classifier for classifying particles introduced together with a transport gas into particles larger than a predetermined particle size and particles smaller than a predetermined particle size, wherein: The classifier includes a plurality of scrapers extending in the vertical direction and arranged circumferentially on an imaginary circle centered on a central axis extending in the vertical direction, and is configured to introduce the particles together with the transport gas from the radially outer side to the radially inner side. The scraper has a collision surface, on which the introduced particles collide, and the particles larger than a predetermined particle size among the collided particles are ejected in the radially outward direction, and the particles smaller than the predetermined particle size are ejected in the radially inward direction. In the collision surface, the angle formed by the tangent line of the imaginary circle and the perpendicular line to the collision surface is larger on the radially outer side than on the radially inner side. The collision surface has a curved surface curved in a protruding manner, In the curved surface, the angle formed by the tangent line of the imaginary circle and the perpendicular line to the collision surface is larger on the radially outer side than on the radially inner side. The scraper has a self-shaping property that allows it to wear in a manner that maintains the curved surface. The operating method of the classifier includes the step of separating the particles into the particles having a larger particle size than a predetermined particle size and the particles having a smaller particle size than a predetermined particle size by the scraper.

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