Crusher, power plant, and operating method of crusher

Abstract

To improve a degree of freedom in design.SOLUTION: A mill includes: a housing 11 forming an outer shell; a crushing table which is provided inside the housing 11, and whose upper surface will be supplied with solid fuel; a crushing roller for crushing solid fuel on the crushing table; a conveying gas supply part for supplying conveying gas into the housing 11 for conveying solid fuel crushed on the crushing table to an outlet port provided in the housing 11; a deposition part 60 for depositing the crushed solid fuel; and a cooling part 70 for cooling the crushed solid fuel deposited in the deposition part 60. An upper surface of the deposition part 60 has an angle relative to a horizontal plane that is a repose angle of the solid fuel or smaller.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a pulverizer, a power generation plant, and a method for operating a pulverizer.

Background Art

[0002] Conventionally, solid fuels such as coal and biomass fuels (carbon-containing solid fuels) are pulverized into fine powders within a predetermined particle size range by a pulverizer (mill) and supplied to a combustion device. The mill sandwiches and pulverizes solid fuels such as coal and biomass fuels fed onto a pulverizing table between the pulverizing table and a pulverizing roller, and among the pulverized solid fuels that have become fine powders, fine powder fuels within a predetermined particle size range are selected by a classifier and conveyed to a boiler by a conveying gas (primary air) supplied from the outer periphery of the pulverizing table, where they are burned in a combustion device. In a thermal power generation plant, steam is generated by heat exchange with combustion gas generated by burning fine powder fuel in a boiler, and the steam rotates and drives a steam turbine, and power generation is performed by rotating and driving a generator connected to the steam turbine.

[0003] Such a mill may be provided with a cooling system for cooling the inside of the mill (for example, Patent Document 1). Patent Document 1 discloses a vertical mill in which a cooling water pipe is connected to a cooling water chamber formed inside a pulverizing table, and the mill is cooled by circulating cooling water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, crushed solid fuel accumulates inside the mill. Solid fuel generates heat through spontaneous oxidation. Furthermore, the accumulated solid fuel (hereinafter referred to as "accumulated material") has insulating properties. Therefore, as the accumulation increases and its thickness increases, it becomes more difficult for the heat generated by spontaneous oxidation to escape to the outside of the accumulation. Consequently, the temperature of accumulation exceeding a certain thickness will continue to rise. When the internal temperature of the accumulation reaches its ignition point, an ignition source (a localized high-temperature area) is generated, which can ignite the surrounding fuel inside the mill, potentially causing rapid combustion inside the mill. On the other hand, with the increasing use of renewable energy in recent years, there is a growing need to crush biomass in conventional coal mills. However, compared to coal, biomass tends to have a larger angle of repose and larger particle size, so it easily settles in areas where the flow of the transport gas is stagnant, making it prone to sedimentation. In addition, bridging occurs in the narrow parts inside the mill, creating easy starting points for sedimentation. Thus, when crushing biomass fuel, sedimentation is particularly likely to occur. Patent Document 1 discloses a system for cooling the inside of a mill, but the system in Patent Document 1 cools the grinding table and is not intended to reduce the temperature of the sediment. Therefore, the system in Patent Document 1 may not be able to suppress the ignition of the sediment. To suppress the ignition of sediment, conventional methods have involved creating a structure within the mill that is steeper than the angle of repose for solid fuel, thereby making it difficult for sediment to accumulate. However, ensuring the angle of repose could limit the design flexibility of the mill. Furthermore, ensuring the angle of repose increases the height of the mill. Since a bunker for storing solid fuel is installed on top of the mill, this could increase the height of the boiler building, potentially increasing the manufacturing and installation costs of the mill and boiler.

[0006] This disclosure is made in view of these circumstances and aims to provide a crusher, a power plant, and a method for operating a crusher that can improve the degree of design freedom. Furthermore, the objective is to provide a crusher, a power plant, and a method for operating the crusher that can reduce manufacturing and installation costs. [Means for solving the problem]

[0007] To solve the above problems, the pulverizer, power plant, and operating method of the pulverizer of this disclosure employ the following means. A pulverizer according to one aspect of the present disclosure comprises a housing forming an outer shell; a pulverizing table provided inside the housing and supplied with solid fuel on its upper surface; pulverizing rollers for pulverizing the solid fuel on the pulverizing table; a conveying gas supply unit for supplying conveying gas into the housing to convey the solid fuel pulverized on the pulverizing table to an outlet provided in the housing; a deposit section for accumulating the pulverized solid fuel; and a cooling unit for cooling the pulverized solid fuel accumulated in the deposit section, wherein the upper surface of the deposit section has an angle with respect to the horizontal plane that is less than or equal to the angle of repose of the solid fuel.

[0008] A method for operating a pulverizer according to one aspect of the present disclosure comprises a housing forming an outer shell, a pulverizing table provided inside the housing and supplied with solid fuel on its upper surface, a pulverizing roller for pulverizing the solid fuel on the pulverizing table, a conveying gas supply unit for supplying conveying gas into the housing to convey the solid fuel pulverized on the pulverizing table to an outlet provided in the housing, a deposit section for accumulating the pulverized solid fuel, and a cooling unit for cooling the pulverized solid fuel accumulated in the deposit section, wherein the angle of the upper surface of the deposit section with respect to the horizontal plane is less than or equal to the angle of repose of the solid fuel, and the method for operating a pulverizer comprises a cooling step of cooling the pulverized solid fuel accumulated in the deposit section by the cooling unit. [Effects of the Invention]

[0009] According to this disclosure, design flexibility can be improved, and manufacturing and installation costs can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram showing a power plant according to the first embodiment of this disclosure. [Figure 2] Figure 1 is a longitudinal cross-section of the mill. [Figure 3] This is an enlarged view of the main part of Figure 2. [Figure 4] Figure 1 is a graph showing the relationship between the passage of time and the temperature of the sediment in the mill. [Figure 5] Figure 1 is a graph showing the relationship between the passage of time and the amount of solid fuel supplied in the mill. [Figure 6] This figure shows a modified example of Figure 3. [Figure 7] This figure shows a modified example of Figure 3. [Figure 8] This figure shows a modified example of Figure 3. [Figure 9] This is an enlarged view of the main part of a mill provided in a power plant according to the second embodiment of this disclosure. [Modes for carrying out the invention]

[0011] An embodiment of the pulverizer, power plant, and operating method of the pulverizer relating to this disclosure will be described below with reference to the drawings.

[0012] [First Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The power plant 1 according to this embodiment includes a solid fuel crushing device 100 and a boiler 200. In the following explanation, "upper" refers to the direction vertically upward, and "upper" in terms such as "top" or "upper surface" refers to the vertically upward part. Similarly, "down" refers to the vertically downward part, and the vertical direction is not strictly accurate and contains some margin of error.

[0013] The solid fuel crushing apparatus 100 of this embodiment is a device that crushes solid fuels (carbon-containing solid fuels) such as coal and biomass fuel, produces fine fuel powder, and supplies it to the burner 220 of the boiler 200. The power generation plant 1 including the solid fuel pulverizing device 100 and the boiler 200 shown in FIG. 1 includes one solid fuel pulverizing device 100, but may also be a system including a plurality of solid fuel pulverizing devices 100 corresponding to each of a plurality of burners 220 of one boiler 200.

[0014] The solid fuel pulverizing device 100 of the present embodiment includes a mill (pulverizer) 10, a coal feeder 20, a blower section 30, a state detection section 40, and a control section 50.

[0015] The mill 10 that pulverizes solid fuels such as coal and biomass fuel supplied to the boiler 200 into pulverized fuel, which is finely powdered solid fuel, may be in a form that pulverizes only coal, a form that pulverizes only biomass fuel, or a form that pulverizes biomass fuel together with coal. Here, the biomass fuel is a renewable bio-derived organic resource, for example, thinned wood, waste wood, driftwood, grasses, waste, sludge, tires, and recycled fuels (pellets and chips) made from these, and is not limited to those presented here. Since the biomass fuel captures carbon dioxide during the growth process of biomass, it is carbon neutral and does not emit carbon dioxide, which is a global warming gas, and thus its utilization is being variously studied.

[0016] As shown in FIGS. 1 and 2, the mill 10 includes a housing 11, a pulverizing table 12, pulverizing rollers 13, a drive section 14, a mill motor 15 that is connected to the drive section 14 and rotationally drives the pulverizing table 12, a rotary classifier 16, a fuel supply section 17, and a classifier motor 18 that rotationally drives the rotary classifier 16. The housing 11 is formed in a cylindrical shape extending in the vertical direction and is a housing that houses the pulverizing table 12, the pulverizing rollers 13, the rotary classifier 16, and the fuel supply section 17. A fuel supply unit 17 is mounted in the center of the ceiling portion 42 of the housing 11. This fuel supply unit 17 supplies solid fuel, which is guided from the bunker 21, into the housing 11. It is positioned vertically at the center of the housing 11, and its lower end extends into the interior of the housing 11.

[0017] A drive unit 14 is installed near the bottom surface 41 of the housing 11, and a grinding table 12, which rotates due to the driving force transmitted from a mill motor 15 connected to this drive unit 14, is rotatably positioned. The crushing table 12 is a circular member in plan view, and is positioned so as to face the lower end of the fuel supply unit 17. The upper surface of the crushing table 12 may have a sloping shape, for example, with the center being lower and the outer surface rising towards the outside, and the outer circumference being bent upward. The fuel supply unit 17 supplies solid fuel (for example, coal or biomass fuel in this embodiment) from above to the crushing table 12 below, and the crushing table 12 crushes the supplied solid fuel between itself and the crushing rollers 13.

[0018] When solid fuel is fed from the fuel supply unit 17 towards the approximate central region of the crushing table 12, the centrifugal force from the rotation of the crushing table 12 guides the solid fuel towards the outer periphery of the crushing table 12, where it is crushed between the crushing table 12 and the crushing rollers 13. The crushed solid fuel is blown upward by the conveying gas (hereinafter referred to as primary air) introduced from the conveying gas passage (hereinafter referred to as primary air passage) 100a, and guided to the rotary classifier 16. An outlet (not shown) is provided on the outer circumference of the grinding table 12 to allow primary air flowing in from the primary air passage 100a to flow out into the space above the grinding table 12 inside the housing 11. A swirling blade (not shown) is installed at the outlet, which imparts a swirling force to the primary air blown out from the outlet. The primary air, given a swirling force by the swirling blade, becomes an airflow with a swirling velocity component, which transports the solid fuel ground on the grinding table 12 to the rotary classifier 16 located above the housing 11. Of the ground solid fuel, those larger than a predetermined particle size are classified by the rotary classifier 16, or they fall without reaching the rotary classifier 16 and are returned to the grinding table 12, where they are ground again between the grinding table 12 and the grinding roller 13.

[0019] The crushing roller 13 is a rotating body that crushes the solid fuel supplied from the fuel supply unit 17 onto the crushing table 12. The crushing roller 13 is pressed against the upper surface of the crushing table 12 and works in cooperation with the crushing table 12 to crush the solid fuel. Although only one grinding roller 13 is shown as a representative example in Figure 1, multiple grinding rollers 13 are arranged at regular intervals in the circumferential direction to press against the upper surface of the grinding table 12. For example, three grinding rollers 13 are arranged at equal intervals in the circumferential direction with a 120° angle interval on the outer circumference. In this case, the parts of the three grinding rollers 13 that contact (press) the upper surface of the grinding table 12 are at equal distances from the rotational axis of the grinding table 12.

[0020] The crushing roller 13 is pivotable up and down by the journal head (support part) 45 and is supported so as to be able to move closer to and further away from the upper surface of the crushing table 12. The crushing roller 13 is supported by the housing 11 by the journal head 45. When the crushing table 12 rotates, the crushing roller 13 rotates along with the crushing table 12 as the crushing table 12 rotates, receiving rotational force from the crushing table 12. When solid fuel is supplied from the fuel supply unit 17, the solid fuel is pressed and crushed between the crushing roller 13 and the crushing table 12.

[0021] The support arm 47 of the journal head 45 is supported by a support shaft 48 whose middle section is aligned horizontally, allowing the crushing roller 13 to swing vertically around the support shaft 48 on the side of the housing 11. A pressing device 49 is provided at the upper end of the support arm 47, which is vertically above it. The pressing device 49 is fixed to the housing 11 and applies a load to the crushing roller 13 via the support arm 47, etc., so as to press the crushing roller 13 against the crushing table 12.

[0022] The drive unit 14 is a device that transmits driving force to the grinding table 12, causing the grinding table 12 to rotate around its central axis. The drive unit 14 is connected to the mill motor 15 and transmits the driving force of the mill motor 15 to the grinding table 12.

[0023] The rotary classifier 16 is located on the upper part of the housing 11 and has a hollow, substantially inverted conical outer shape. The rotary classifier 16 is equipped with a plurality of blades 16a extending vertically on its outer circumference. Each blade 16a is provided at a predetermined interval (equal intervals) around the central axis of the rotary classifier 16. The rotary classifier 16 is a device that classifies solid fuel crushed by the crushing table 12 and crushing rollers 13 (hereinafter, the crushed solid fuel will be referred to as "crushed fuel") into particles larger than a predetermined particle size (for example, 70-100 μm for coal) (hereinafter, crushed fuel with a particle size exceeding the predetermined particle size will be referred to as "coarse fuel") and particles smaller than or equal to the predetermined particle size (hereinafter, crushed fuel with a particle size smaller than or equal to the predetermined particle size will be referred to as "fine fuel"). The rotary classifier 16, which classifies by rotation, is also called a rotary separator, and is driven by a classifier motor 18 controlled by the control unit 50, rotating around the fuel supply unit 17 around a cylindrical shaft (not shown) that extends vertically in the housing 11. Furthermore, a fixed classifier may be used, which has a fixed, hollow, inverted cone-shaped casing and multiple fixed swivel vanes instead of blades 16a on the outer circumference of the casing.

[0024] The crushed fuel that reaches the rotary classifier 16 is knocked down by the centrifugal force generated by the rotation of the blades 16a and the centripetal force from the airflow of the primary air. The larger diameter coarse fuel is knocked down by the blades 16a and returned to the crushing table 12 where it is crushed again, while the fine fuel is guided to the outlet port (outlet section) 19 located in the ceiling section 42 of the housing 11. The fine fuel classified by the rotary classifier 16 is discharged from the outlet port 19 along with the primary air into the fine fuel supply channel 100b and supplied to the burner 220 of the boiler 200. The fine fuel supply channel 100b is also called the pulverized coal channel when the solid fuel is coal.

[0025] The fuel supply unit 17 is mounted so that its lower end extends vertically into the interior of the housing 11, penetrating the ceiling portion 42 of the housing 11. The fuel supply unit 17 supplies solid fuel, which is fed in from its upper part, to the approximate central area of ​​the crushing table 12. The fuel supply unit 17 is supplied with solid fuel from the coal feeder 20.

[0026] The coal feeder 20 comprises a conveying unit 22 and a coal feeder motor 23. The conveying unit 22 is, for example, a belt conveyor, and is driven by the power supplied by the coal feeder motor 23 to transport the solid fuel discharged from the lower end of the downspout 24 located directly below the bunker 21 to the upper part of the fuel supply unit 17 of the mill 10, and to feed it into the fuel supply unit 17. Normally, primary air is supplied to the mill 10 to transport the pulverized fuel to the burner 220, and the pressure is higher than that of the coal feeder 20 and bunker 21. The downspout 24, a vertically extending pipe located directly below the bunker 21, holds fuel in a layered state inside, and the solid fuel layer stacked within the downspout 24 ensures a seal that prevents the primary air and pulverized fuel from the mill 10 side from flowing back to the bunker 21 side. The amount of solid fuel supplied to the mill 10 is adjusted, for example, by the moving speed of the belt conveyor in the transport section 22.

[0027] On the other hand, chips and pellets of biomass fuel before crushing have a more uniform particle size (for example, pellets are about 6-8 mm in diameter and 40 mm or less in length) and are lighter than coal fuel (i.e., coal before crushing has a particle size of about 2-50 mm). Therefore, when biomass fuel is stored in the downspout 24, the gaps formed between each biomass fuel in the solid fuel layer within the downspout 24 are larger than in the case of coal fuel. Furthermore, the state of the gaps formed between each biomass fuel in the solid fuel layer within the downspout 24 is not necessarily constant and may fluctuate. Therefore, compared to the case of coal fuel, relatively large gaps are formed between the biomass fuel chips and pellets in the downspout 24. As a result, primary air and crushed fuel can pass from inside the mill 10 through the gaps formed in the solid fuel layer, causing a backflow of primary air and crushed fuel from inside the mill 10 through the coal feeder 20 to the bunker 21. This can cause a decrease in the pressure inside the mill 10, and this possibility is higher than in the case of coal fuel. Furthermore, if primary air and pulverized fuel flow back into the bunker 21, causing a decrease in pressure inside the mill 10, various problems may arise that hinder the stable operation of the solid fuel pulverizer 100 and boiler 200, such as deterioration of the transportability of pulverized fuel inside the mill 10, generation of dust inside the coal feeder 20 and above the bunker 21, ignition of solid fuel inside the coal feeder 20, the bunker 21 and downspout 24, and a decrease in the amount of fine fuel transported to the burner 220. For this reason, a rotary valve (not shown) may be installed in the middle of the fuel supply section 17 that goes from the coal feeder 20 to the inside of the mill 10 to suppress the occurrence of backflow of primary air and crushed fuel that goes from inside the mill 10 through the coal feeder 20 to the bunker 21.

[0028] The blowing unit 30 is a device that dries the crushed fuel and blows primary air for transport to the rotary classifier 16 into the inside of the housing 11 via a duct connected to the housing 11. In this embodiment, the blower unit 30 includes a primary air fan (PAF) 31, a hot gas passage 30a, a cold gas passage 30b, a hot gas damper 30c, and a cold gas damper 30d in order to appropriately adjust the flow rate and temperature of the primary air blown into the housing 11.

[0029] In this embodiment, the hot gas flow path 30a supplies a portion of the air (outside air) sent from the primary air ventilator 31 as hot gas that has been heated by passing it through a heat exchanger 34, such as an air preheater. A hot gas damper 30c is provided downstream of the hot gas flow path 30a. The opening degree of the hot gas damper 30c is controlled by the control unit 50. The opening degree of the hot gas damper 30c determines the flow rate of the hot gas supplied from the hot gas flow path 30a.

[0030] The cold gas passage 30b supplies a portion of the air discharged from the primary air ventilator 31 as cold gas at room temperature. A cold gas damper 30d is provided downstream of the cold gas passage 30b. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The opening degree of the cold gas damper 30d determines the flow rate of cold gas supplied from the cold gas passage 30b.

[0031] In this embodiment, the flow rate of the primary air is the sum of the flow rate of the hot gas supplied from the hot gas channel 30a and the flow rate of the cold gas supplied from the cold gas channel 30b. The temperature of the primary air is determined by the mixing ratio of the hot gas supplied from the hot gas channel 30a and the cold gas supplied from the cold gas channel 30b, and is controlled by the control unit 50. Alternatively, the oxygen concentration of the primary air blown into the housing 11 from the primary air passage 100a may be adjusted by introducing a portion of the combustion gas discharged from the boiler 200 via a gas recirculation ventilator (not shown) into the hot gas supplied from the hot gas passage 30a and mixing them.

[0032] In this embodiment, the state detection unit 40 of the mill 10 transmits the measured or detected data to the control unit 50. The state detection unit 40 in this embodiment is, for example, a differential pressure measuring means, and measures the differential pressure of the mill 10 between the pressure at the point where primary air flows from the primary air passage 100a into the inside of the housing 11 and the pressure at the outlet port 19 where primary air and fine fuel are discharged from the inside of the housing 11 to the fine fuel supply passage 100b. The increase or decrease in this differential pressure of the mill 10 corresponds to the increase or decrease in the amount of grinding fuel circulating between the vicinity of the rotary classifier 16 and the vicinity of the grinding table 12 inside the housing 11 due to the classification effect of the rotary classifier 16. In other words, by adjusting the rotational speed of the rotary classifier 16 in accordance with the differential pressure of the mill 10, the amount of fine fuel discharged from the outlet port 19 can be adjusted in relation to the amount of solid fuel supplied to the mill 10. This allows for a stable supply of an amount of fine fuel corresponding to the amount of solid fuel supplied to the mill 10 to the burner 220 installed in the boiler 200, within a range where the particle size of the fine fuel does not affect the combustibility of the burner 220. Furthermore, the state detection unit 40 in this embodiment is, for example, a temperature measuring means, which detects the temperature of the primary air supplied into the housing 11 (primary air temperature at the mill inlet) and the temperature of the primary air from the space above the grinding table 12 inside the housing 11 to the outlet port 19, and controls the air blower 30 so as not to exceed the upper limit temperature. The upper limit temperature is determined considering the possibility of ignition of the solid fuel, etc. The primary air is cooled inside the housing 11 as the grinding fuel is dried and transported, and the temperature of the primary air at the outlet port 19 is, for example, about 60 to 90 degrees.

[0033] The control unit 50 is a device that controls each part of the solid fuel crushing apparatus 100. The control unit 50 may, for example, transmit a drive command to the mill motor 15 to control the rotation speed of the grinding table 12. The control unit 50, for example, transmits a drive command to the classifier motor 18 to control the rotational speed of the rotary classifier 16 and adjust the classification performance, thereby optimizing the differential pressure of the mill 10, i.e., the amount of pulverized fuel circulating inside the mill 10, to a predetermined range, and thereby enabling a stable supply of fine fuel to the burner 220. Furthermore, the control unit 50 can adjust the amount of solid fuel supplied (coal amount) that the transport unit 22 transports and supplies to the fuel supply unit 17 by transmitting a drive instruction to the coal feeder motor 23 of the coal feeder 20, for example. Furthermore, the control unit 50 can adjust the flow rate and temperature of the primary air by controlling the opening of the hot gas damper 30c and the cold gas damper 30d by transmitting an opening instruction to the blower unit 30. Specifically, the control unit 50 controls the opening of the hot gas damper 30c and the cold gas damper 30d so that the flow rate of the primary air supplied to the inside of the housing 11 and the temperature of the primary air at the outlet port 19 are predetermined values ​​set according to the amount of coal supplied for each type of solid fuel.

[0034] 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. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in the ROM or other storage medium, provided in a state where it is stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc.

[0035] Next, a boiler 200 that generates steam by combustion using fine fuel supplied from a solid fuel crushing device 100 will be described. The boiler 200 is equipped with a furnace 210 and a burner 220.

[0036] The burner 220 is a device that burns the pulverized fuel to form a flame using primary air containing pulverized fuel supplied from the pulverized fuel supply channel 100b and secondary air supplied by heating outside air (forced draft fan) 32 in a heat exchanger 34. The combustion of the pulverized fuel takes place in the furnace 210, and the high-temperature combustion gas is discharged to the outside of the boiler 200 after passing through heat exchangers such as an evaporator, superheater, and economizer (not shown).

[0037] The combustion gas discharged from the boiler 200 is subjected to predetermined treatment by environmental equipment (denitrification equipment, electrostatic precipitator, etc., not shown), and heat exchange takes place in a heat exchanger 34, such as an air preheater, between the air supplied from the primary air ventilator 31 and the air supplied from the forced draft ventilator 32. The gas is then guided to a chimney (not shown) via an induced draft fan (IDF) 33 and released into the outside air. The air supplied from the primary air ventilator 31, heated by the combustion gas in the heat exchanger 34, is supplied to the aforementioned hot gas flow path 30a. The feedwater to each heat exchanger of the boiler 200 is heated in an economizer (not shown), then further heated in an evaporator (not shown) and a superheater (not shown) to generate high-temperature, high-pressure steam, which is sent to a steam turbine (not shown), which is the power generation unit, to rotate the steam turbine, and then rotates a generator (not shown) connected to the steam turbine to generate electricity, thus constituting the power plant 1.

[0038] Next, the deposit section 60 and cooling section 70 provided in the mill 10 will be described in detail.

[0039] As shown in Figures 2 and 3, recesses 61 are formed in the side walls of the housing 11, recessed outward from the mill 10, to house the journal heads 45 that support the grinding rollers 13 or their associated components inside the housing 11. As described above, three grinding rollers 13 are provided at regular intervals in the circumferential direction, so three recesses 61 are also formed at regular intervals in the circumferential direction to correspond to the journal heads 45 of each grinding roller 13. The configuration of each recess 61 is substantially the same. The side wall of the recess 61 or a part thereof may be configured as a removable roller cover (cover portion) 62 to allow the crushing roller 13 and journal head 45 or their associated parts to be removed from the mill 10 to the outside during maintenance. The roller cover 62 constitutes the side wall of the mill 10 as part of the housing 11 and retains the solid fuel and primary air inside the mill 10. In this embodiment, the side wall of the recess 61 is composed of the roller cover 62. In Figure 2, for illustrative purposes, the dividing surface of the roller cover 62 in the housing 11 is shown with a dashed line. Also, in Figure 3, for illustrative purposes, the roller cover 62 is not shown, and the side wall of the recess 61 is shown as the housing 11.

[0040] A deposit section 60 is provided at the lower end of the inner wall of the recess 61. In this embodiment, the deposit section 60 is located below the journal head 45 and within the internal space of the mill 10, which is formed by the housing 11. The deposit section 60 is located within the internal space of the recess 61. The deposit section 60 is a plate-shaped member that is part of the housing 11, and its upper surface is a horizontal plane. That is, the angle of the upper surface of the deposit section 60 with respect to the horizontal plane (hereinafter referred to as the "inclination angle") is 0 degrees. Furthermore, the accumulation section 60 is provided, for example, above the grinding table 12. In other words, the accumulation section 60 is provided between the grinding table 12 and the outlet port 19 in the primary airflow.

[0041] As described above, crushed fuel circulates inside the housing 11. As a result, the crushed fuel accumulates on the upper surface of the accumulation section 60, as shown in Figure 3. Hereinafter, the crushed fuel accumulated on the upper surface of the accumulation section 60 will be referred to as "accumulated material S". In this embodiment, the heat exchange section 71 of the cooling section 70, which will be described later, is located on the upper surface of the accumulation section 60. Therefore, the accumulated material S accumulates on the upper surface of the accumulation section 60 via the heat exchange section 71.

[0042] Although an example in which the upper surface of the deposition section 60 is a horizontal plane has been described, this disclosure is not limited to this. The upper surface of the deposition section 60 only needs to be on which sediment S is deposited, and may, for example, be inclined with respect to the horizontal plane. However, if it is inclined, the inclination angle of the upper surface of the deposition section 60 is set to be less than or equal to the angle of repose of the sediment S. By inclining the upper surface of the deposition section 60 in this way, the amount of sediment S deposited in the deposition section 60 can be adjusted.

[0043] The cooling unit 70 includes a heat exchange unit 71 provided on the upper surface of the deposit unit 60, a first cooling water pipe 72 through which cooling water supplied to the heat exchange unit 71 flows, a second cooling water pipe 73 through which cooling water discharged from the heat exchange unit 71 flows, and a heat dissipation unit 74 that releases heat from the cooling water.

[0044] The first cooling water pipe 72 and the second cooling water pipe 73 connect the heat exchange section 71 and the heat dissipation section 74. As a result, cooling water circulates between the heat exchange section 71 and the heat dissipation section 74 via the first cooling water pipe 72 and the second cooling water pipe 73. The first cooling water pipe 72 is provided with an on-off valve 75. The on-off valve 75 can be switched between an open state and a closed state by the control unit 50. Note that the fluid circulating in the cooling section 70 is not limited to cooling water. Any refrigerant capable of cooling the deposit S is acceptable.

[0045] The heat exchange unit 71 is located inside the housing 11. The heat exchange unit 71 is placed on the deposit unit 60 so as to cover a part or all of the upper surface of the deposit unit 60. The upper surface of the heat exchange unit 71 is a horizontal plane. However, the upper surface of the heat exchange unit 71 may be inclined with respect to the horizontal plane. In that case, the inclination angle of the upper surface of the heat exchange unit 71 is preferably less than or equal to the angle of repose of the solid fuel (deposit S). The heat exchange unit 71 cools the deposit S by exchanging heat with the supplied cooling water. That is, the heat from the deposit S is absorbed by the heat exchange unit 71 as shown by arrow A1.

[0046] The heat exchange section 71 may be covered with a wear-resistant section made of a highly wear-resistant material. This configuration can suppress wear on the heat exchange section 71. Furthermore, the wear-resistant section is preferably made of a material with a high heat transfer coefficient. This configuration can suppress a decrease in cooling performance. Examples of materials for forming the wear-resistant section include hardened plates, high-chromium cast iron, and ceramics. Furthermore, the heat exchange section 71 may have a plurality of plate-shaped fins (not shown) that protrude upward from its upper surface. With this configuration, when sediment S accumulates on the upper surface of the heat exchange section 71, the fins will be located inside the sediment S. Therefore, the inside of the sediment S can be cooled via the fins. The temperature of the sediment S increases towards the center. Therefore, by cooling the inside of the sediment S, the sediment S can be effectively cooled. Note that the shape of the fins is not limited to plates; for example, they may be rod-shaped.

[0047] The heat dissipation unit 74 is located outside the housing 11. The heat dissipation unit 74 cools the cooling water by exchanging heat between the cooling water heated in the heat exchange unit 71 and the outside air. Note that the medium with which the cooling water exchanges heat is not limited to outside air, but may be, for example, water. Furthermore, the heat dissipated by the heat dissipation section 74 may be used by other devices in the power plant 1. For example, the heat dissipation section 74 may be installed in the hot gas flow path 30a. In this case, the heat dissipation section 74 heats the air sent from the primary air ventilator 31 by exchanging heat between the air (outside air) sent from the primary air ventilator 31 and the cooling water (cooling water heated in the heat exchange section 71). In this way, the energy efficiency of the power plant 1 can be improved by using the heat absorbed by the heat exchange section 71 by other devices in the power plant 1.

[0048] In this embodiment, an example in which the heat exchange unit 71 is placed on the upper surface of the deposit unit 60 has been described, but the disclosure is not limited to this. The heat exchange unit 71 may be positioned in contact with the lower surface of the deposit unit 60. In other words, the heat exchange unit 71 may be provided outside the housing 11. When the heat exchange unit 71 is positioned in contact with the lower surface of the deposit unit 60, heat exchange occurs between the heat exchange unit 71 and the deposit S via the deposit unit 60. By positioning the heat exchange unit 71 outside the housing 11 in this way, damage such as wear to the heat exchange unit 71 can be suppressed. In addition, since the first cooling water pipe 72 and the second cooling water pipe 73 do not need to penetrate the housing 11, the installation work of the cooling unit 70 can be simplified.

[0049] Furthermore, the mill 10 of this embodiment is equipped with a sediment temperature detection unit (temperature detection unit) 76 that measures the temperature of the sediment S deposited in the deposit section 60. The means by which the sediment temperature detection unit 76 detects the temperature of the sediment S is not particularly limited. For example, the temperature of the sediment S may be measured directly with a temperature sensor or the like, or the temperature of the sediment S may be detected indirectly by measuring the temperature of the deposit section 60 in contact with the sediment S with a temperature sensor or the like. The sediment temperature detection unit 76 transmits the detected temperature to the control unit 50.

[0050] The control unit 50 controls whether the cooling unit 70 cools the sediment S based on the temperature detected by the sediment temperature detection unit 76. The control unit 50 stores a first threshold (T1) and a second threshold (T2) that is lower than the first threshold. As shown in Figure 4, the control unit 50 opens the on-off valve 75 when the temperature detected by the sediment temperature detection unit 76 is equal to or greater than the first threshold (T1) (see times t1 and t3 in Figure 4). This causes the control unit 50 to direct the cooling water to the heat exchange unit 71, and the cooling unit 70 to cool the sediment S. The control unit 50 also closes the on-off valve 75 when the temperature detected by the sediment temperature detection unit 76 is equal to or less than the second threshold (see time t2 in Figure 4). This causes the control unit 50 to stop the circulation of the cooling water, and the cooling unit 70 does not cool the sediment S.

[0051] However, the control performed by the control unit 50 is not limited to this. For example, the control unit 50 may control whether or not the cooling unit 70 cools the deposit S based on the amount of solid fuel supplied from the fuel supply unit 17 to the mill 10 (hereinafter sometimes referred to as "coal supply amount"). When the amount of supplied solid fuel increases, the amount of crushed fuel circulating within the mill 10 also increases. As a result, the amount of deposit S accumulated in the deposit unit 60 also increases. When the amount of deposit S increases, the temperature inside the deposit S rises. Therefore, when the amount of supplied solid fuel is equal to or greater than a predetermined threshold (C1), the on-off valve 75 is opened. This causes the control unit 50 to direct cooling water to the heat exchange unit 71, and the cooling unit 70 to cool the deposit S. Also, when the amount of supplied solid fuel is lower than the predetermined threshold (C1), the control unit 50 closes the on-off valve 75. This causes the control unit 50 to stop the circulation of cooling water, and the cooling unit 70 does not cool the deposit S. Therefore, in the example shown in Figure 5, the on-off valve 75 is closed when the supply of solid fuel is started. At timing t4, when the amount of solid fuel supplied (coal amount) becomes C1 or greater, the control unit 50 opens the on-off valve 75. Also, at timing t5, when the amount of solid fuel supplied (coal amount) becomes less than C1, the control unit 50 closes the on-off valve 75.

[0052] Furthermore, the control unit 50 may control whether or not the cooling unit 70 cools the deposit S based on the amount of heat exchanged by the cooling unit 70. The amount of heat exchanged by the cooling unit 70 may be determined, for example, by the temperature change of the cooling water.

[0053] According to this embodiment, the following effects and advantages are achieved. In this embodiment, a cooling unit 70 is provided to cool the sediment S accumulated in the sediment section 60. By cooling the sediment S with the cooling unit 70, the rise in temperature of the sediment S can be suppressed. This suppresses spontaneous combustion of the sediment S. Therefore, the safety of the mill 10 can be improved.

[0054] Furthermore, in this embodiment, the cooling unit 70 cools the sediment S, thereby suppressing the spontaneous combustion of the sediment S. This eliminates the need for a structure that suppresses the accumulation of sediment S in order to suppress the spontaneous combustion of sediment S. Therefore, the design flexibility of the mill 10 can be improved compared to a structure that suppresses the accumulation of sediment S. In addition, manufacturing costs can be reduced compared to a structure that suppresses the accumulation of sediment S. A structure that suppresses the accumulation of sediment S is, for example, a structure that provides a slope greater than the angle of repose inside the mill 10, or a structure that provides a nozzle for injecting gas to blow away the sediment S.

[0055] Furthermore, in this embodiment, the angle of the upper surface of the loading section 60 with respect to the horizontal plane (hereinafter referred to as the "inclination angle") is less than or equal to the angle of repose of the solid fuel. This makes it possible to suppress the height of the mill 10 compared to the case where the inclination angle of the upper surface of the loading section 60 is greater than the angle of repose. Therefore, the mill 10 can be made smaller, and thus the increase in the manufacturing and installation costs of the mill 10 can be suppressed. In addition, the increase in the manufacturing and installation costs of the boiler 200 due to the increase in the height of the boiler building caused by the increase in the height of the mill 10 can be suppressed. Furthermore, since the inclination angle is less than or equal to the angle of repose, workers performing maintenance or other tasks inside the mill 10 can work in a stable posture. Therefore, the efficiency of the work performed by the workers can be improved. In addition, the safety of the workers can be improved.

[0056] Furthermore, in this embodiment, the inclination angle of the upper surface of the deposit section 60 is set to be less than or equal to the angle of repose of the solid fuel. That is, deposits S are more easily deposited in the deposit section 60. When deposits S are deposited in the deposit section 60, a portion of the mill 10 is covered by the deposits S inside the housing 11. The area covered by the deposits S does not come into direct contact with the solid fuel transported by the primary air, so wear is less likely to occur. Therefore, in this embodiment, wear inside the mill 10 can be suppressed.

[0057] Because primary air has difficulty flowing into the recess 61 of the housing 11, deposits S tend to accumulate there. Also, if the gap between the inside of the recess 61 of the housing 11 and the journal head 45 is small, deposits S adhere to bridge the recess 61 of the housing 11 and the journal head 45, and accumulation is likely to occur starting from these attached deposits S. In this embodiment, the cooling unit 70 cools the deposit S that accumulates in the deposit area 60 inside the recess 61 of the housing 11. This allows the deposit S that accumulates inside the recess 61 of the housing 11, where accumulation is likely to occur, to be cooled. Therefore, spontaneous combustion of the deposit S can be suppressed more effectively, thereby improving the safety of the mill 10.

[0058] [Variation 1] One modified example of the cooling unit 70 of this embodiment will be explained with reference to Figure 6. As shown in Figure 6, the modified cooling unit 110 includes a cooling air pipe 111 extending horizontally and an injection unit 112 formed in the cooling air pipe 111.

[0059] The cooling air pipe 111 is a pipe that extends horizontally. The cooling air pipe 111 is located below the journal head 45 and above the accumulation section 60. Cooling air flows through the inside of the cooling air pipe 111. The injection section 112 is formed near the lower end of the cooling air pipe 111. The injection section 112 is a hole formed in the cooling air pipe 111. The injection section 112 is formed to face the deposit section 60. The injection section 112 injects cooling air R that flows inside the cooling air pipe 111. Specifically, the injection section 112 injects cooling air onto the deposit S accumulated in the deposit section 60. This allows the deposit S to be cooled by the cooling air. In detail, as shown by arrow A2 in Figure 6, heat dissipation of the deposit S can be promoted.

[0060] The cooling air may be a portion of the sealing air supplied to the journal head 45. In the mill 10, sealing air flows from the inside to the outside of the gap formed between the rotating member and the stationary member to prevent the grinding fuel from flowing into the gap. As shown by arrow S1 in Figures 2 and 6, sealing air is also supplied to the journal head 45. A branch pipe 113 branches off from the piping (see S1) that leads the sealing air to the journal head 45. The downstream end of the branch pipe 113 is connected to the cooling air pipe 111. Therefore, a portion of the sealing air is led to the cooling air pipe 111 via the branch pipe 113. Thus, a portion of the sealing air can be used as cooling air.

[0061] The number of injection units 112 may be one or multiple. If multiple units are formed, they are arranged at predetermined intervals along the longitudinal direction of the cooling air pipe 111. Furthermore, the cooling unit 110 may inject cooling air to cover substantially the entire area of ​​the deposition unit 60.

[0062] [Variation 2] One modified example of the cooling unit 70 of this embodiment will be explained with reference to Figure 7. As shown in Figure 7, the modified cooling unit 120 has a refrigerant pipe 121 that extends horizontally. The refrigerant pipe 121 is provided above the deposit section 60 and spaced apart from the deposit section 60. In detail, the refrigerant pipe 121 is positioned approximately in the center of the deposit S when the deposit S accumulates in the deposit section 60. Refrigerant flows inside the refrigerant pipe 121. The cooling unit 120 cools the deposit S by exchanging heat between the refrigerant flowing inside the refrigerant pipe 121 and the deposit S. The refrigerant heated by the heat of the deposit S is dissipated in a heat dissipation section (not shown). The refrigerant that has been dissipated in the heat dissipation section flows again through the refrigerant pipe 121. The temperature of the sediment S increases towards the center. According to this modified example, the sediment S can be effectively cooled by cooling the central part of the sediment S.

[0063] [Variation 3] One modified example of the cooling unit 70 of this embodiment will be explained with reference to Figure 8. As shown in Figure 8, the modified cooling unit 130 includes a plurality of lower fins 131 that protrude downward from the lower surface of the deposit section 60, a plurality of side fins 132 that protrude from the outer surface of the side wall of the housing 11 that is in contact with the deposit S, and a cooling fan 133 that blows air to the lower fins 131 and the side fins 132. The cooling unit 130 can cool the deposit S via the deposit section 60 and the side walls of the housing 11 by exchanging heat between the air from the cooling fan 133 and the bottom fins 131 and side fins 132.

[0064] [Variation 4] A modified example of the cooling unit 70 in this embodiment will be described. The cooling section may include a thermoelectric element (not shown), such as a Peltier element, arranged to contact the upper or lower surface of the deposit section 60, to cool the deposit S.

[0065] [Second Embodiment] Next, a second embodiment of this disclosure will be described with reference to Figure 9. The mill 10 of this disclosure differs from the first embodiment in that a plate-shaped plate portion 150 is provided on the inner circumferential surface of the housing 11, and a cooling portion 140 is provided for cooling the deposit S that accumulates on the plate portion 150. Other aspects are the same as in the first embodiment, so the same reference numerals are used for similar components, and their detailed descriptions are omitted.

[0066] As shown in Figure 9, the inner circumferential surface of the housing 11 is provided with multiple plate portions 150 that extend horizontally toward the center of the housing 11. The multiple plate portions 150 are arranged at predetermined intervals along the vertical direction of the housing 11. Furthermore, the multiple plate portions 150 are arranged such that the lowest plate portion 150 is positioned higher than, for example, the uppermost plate portion 150 of the crushing table 12. Furthermore, the multiple plate portions 150 are arranged such that the uppermost plate portion 150 is positioned where, for example, the crushed fuel ejected from the rotary classifier 16 will strike. The structure of each plate portion 150 is substantially the same.

[0067] The plate portion 150 is provided over substantially the entire circumferential area of ​​the inner surface of the housing 11. Furthermore, the plate portion 150 is positioned so that its upper and lower surfaces are horizontal. That is, the upper and lower surfaces of the plate portion 150 have an inclination angle of 0 degrees. Consequently, sediment S accumulates on the upper surface of the plate portion 150. In other words, the plate portion 150 constitutes the sedimentation section 60.

[0068] Although an example in which the upper and lower surfaces of the plate portion 150 are horizontal has been described, this disclosure is not limited to this. The upper and lower surfaces of the plate portion 150 only need to be on which sediment S is deposited, and may, for example, be inclined with respect to the horizontal plane. However, if they are inclined, the inclination angle of the upper and lower surfaces of the plate portion 150 should be set to be less than or equal to the angle of repose of the sediment S. In this way, the amount of sediment S deposited on the plate portion 150 can be adjusted by inclining the upper and lower surfaces of the plate portion 150.

[0069] The cooling unit 140 includes a heat exchange unit 141 provided on the outer circumferential surface of the side wall of the housing 11 on which the plate portion 150 is provided, a third cooling water pipe 142 through which cooling water supplied to the heat exchange unit 141 flows, a fourth cooling water pipe 143 through which cooling water discharged from the heat exchange unit 141 flows, and a heat dissipation unit 74 (not shown) that releases heat from the cooling water. The cooling unit 140 of this embodiment is substantially the same as the cooling unit 140 of the first embodiment, except for the installation position of the heat exchange unit 141, so a detailed explanation is omitted. The heat exchange unit 141 according to this embodiment is provided so as to be in contact with the outer circumferential surface of the housing 11. Furthermore, the heat exchange unit 141 is located outside the housing 11.

[0070] According to this embodiment, the following effects and advantages are achieved. In this embodiment, multiple plate sections 150 are provided. As a result, as shown in Figure 9, the crushed fuel circulating inside the housing 11 accumulates as sediment S on the upper surface of the plate sections 150.

[0071] As shown by arrow A3 in Figure 9, the inner circumferential surface of the housing 11 is prone to wear because it is easily struck by the crushed fuel conveyed by primary air from the upper surface of the crushing table 12. Furthermore, it is prone to wear because it is easily struck by the crushed fuel ejected from the rotary classifier 16. In this embodiment, a plate portion 150 extending from the inner circumferential surface of the housing 11 is provided as the deposit portion 60. As described above, deposits S accumulate on the upper surface of the plate portion 150. As a result, the inner circumferential surface of the housing 11 is covered with deposits S. This prevents the crushed fuel conveyed by the primary air and the crushed fuel ejected from the rotary classifier 16 from directly contacting the inner circumferential surface of the housing 11. Therefore, wear on the inner circumferential surface of the housing 11 can be suppressed. The length of the plate portion 150 and the spacing between them should be such that they do not affect the streamlines of the primary air blowing up, and the angle of repose of the deposits S accumulated on the plate portion 150 should be taken into consideration so that the inner circumferential surface of the housing 11 is covered with deposits S.

[0072] Furthermore, the deposit S accumulated on the upper surface of the plate portion 150 is cooled by the cooling portion 140. Therefore, spontaneous combustion of the deposit S accumulated on the plate portion 150 can be suppressed, thereby improving the safety of the mill 10.

[0073] This disclosure is not limited to the embodiments described above, and can be modified as appropriate without departing from its essence.

[0074] For example, in the above embodiment, an example was described in which the deposit section 60 is provided on the side surface of the housing 11 inside the recess 61 of the housing 11, but this disclosure is not limited thereto. The deposit section 60 may be provided at any position inside the housing 11. For example, the deposit section 60 may be a deflection plate 63 (see Figure 2) provided on the inner circumferential surface of the housing 11. That is, the inclination angle of the upper surface of the deflection plate 63 may be 0 degrees or more and less than or equal to the repose angle. The deflection plate 63 is provided between adjacent crushing rollers 13 in the circumferential direction and at the same height as the crushing rollers 13, and deflects the primary airflow toward the center of the housing 11. In this modified example, a cooling section is provided on the upper surface of the deflection plate 63 to cool the deposit S accumulated thereon. The configuration of the cooling section may be any of the configurations of the cooling section described in the above embodiment. In this modified example, the sediment S accumulated on the drift plate 63 can be cooled. Therefore, spontaneous combustion of the sediment S can be suppressed, thereby improving the safety of the mill 10.

[0075] Alternatively, the deposit section 60 may be provided on the bottom surface 64 that defines the lower end of the internal space of the rotary classifier 16 (the space inside the circumferentially arranged blades 16a). That is, the inclination angle of the bottom surface 64 may be 0 degrees or more and less than or equal to the repose angle. In this case, a cooling section 70 is provided to cool the sediment S deposited on the bottom surface 64. The configuration of the cooling section 70 may be any of the configurations of the cooling section 70 described in the above embodiment, but since a sealing gas is supplied to the rotary classifier 16 as shown by arrows S2 and S3 in Figure 2, a portion of the sealing gas may be directed to the bottom surface 64 and blown onto the sediment S deposited on the bottom surface 64 to cool the sediment S. In this modified example, the sediment S accumulated on the bottom surface 64 of the rotary classifier 16 can be cooled. Therefore, spontaneous combustion of the sediment S can be suppressed, thereby improving the safety of the mill 10.

[0076] The crusher, power plant, and operating method of the crusher described in the above-described embodiment can be understood, for example, as follows. A crusher (10) according to one aspect of the present disclosure comprises a housing (11) forming an outer shell, a crushing table (12) provided inside the housing (11) on which solid fuel is supplied to the upper surface, a crushing roller (13) for crushing the solid fuel on the crushing table (12), a conveying gas supply unit (30) for supplying conveying gas into the housing (11) to convey the solid fuel crushed on the crushing table (12) to an outlet (19) provided in the housing (11), a deposit unit (60) on which the crushed solid fuel is deposited, and a cooling unit (70) for cooling the crushed solid fuel deposited in the deposit unit (60), wherein the angle of the upper surface of the deposit unit (60) with respect to the horizontal plane is less than or equal to the angle of repose of the solid fuel.

[0077] The above configuration includes a cooling unit for cooling the crushed solid fuel (hereinafter referred to as "sediment") deposited in the sediment section. By cooling the sediment with the cooling unit, the rise in temperature of the sediment can be suppressed. This suppresses spontaneous combustion of the sediment. Therefore, the safety of the crusher can be improved.

[0078] Furthermore, in the above configuration, the cooling unit cools the sediment, thereby suppressing spontaneous combustion of the sediment. This eliminates the need for a structure that suppresses sediment accumulation in order to prevent spontaneous combustion of the sediment. Therefore, the design flexibility of the crusher can be improved compared to a crusher with a structure that suppresses sediment accumulation. In addition, manufacturing costs can be reduced compared to a structure that suppresses sediment accumulation. A structure that suppresses sediment accumulation is, for example, a structure that provides a slope greater than the angle of repose inside the mill, or a structure that provides a nozzle that injects gas to blow away the sediment.

[0079] Furthermore, in the above configuration, the angle of the top surface of the deposit section with respect to the horizontal plane (hereinafter referred to as the "inclination angle") is less than or equal to the angle of repose of the solid fuel. This allows the height of the crusher to be suppressed compared to the case where the inclination angle of the top surface of the deposit section is greater than the angle of repose. Therefore, the crusher can be made smaller, and thus the increase in the manufacturing and installation costs of the crusher can be suppressed. In addition, the increase in the height of the boiler building due to the increase in the height of the mill can suppress the increase in the manufacturing and installation costs of the boiler. Furthermore, since the inclination angle is below the angle of repose, workers performing maintenance or other tasks inside the crusher can work in a stable posture. Therefore, the efficiency of the work performed by the workers can be improved. In addition, the safety of the workers can be improved.

[0080] Furthermore, in the above configuration, the inclination angle of the upper surface of the deposit section is set to be less than or equal to the angle of repose of the solid fuel. In other words, deposits are more likely to accumulate in the deposit section. When deposits accumulate in the deposit section, a part of the crusher inside the casing is covered by the deposits. The area covered by the deposits does not come into direct contact with the solid fuel transported by the transport gas or the solid fuel ejected from the rotary classifier, so wear is less likely to occur. Therefore, the above configuration can suppress wear inside the crusher. The accumulation section may, for example, be located inside the housing, between the grinding table and the outlet section.

[0081] Furthermore, a pulverizer according to one aspect of the present disclosure includes a support portion (45) that supports the pulverizing roller (13) in the housing (11), and a recess (61) that houses the support portion (45), wherein the accumulation portion (60) is located in the internal space of the recess (61).

[0082] Because the internal space of the recess (61) is difficult for the transport gas to flow into, sediment tends to accumulate there. Also, if the gap between the inner surface of the recess (61) and the support part (45) is small, sediment adheres to bridge the recess (61) and the support part (45), and this attached sediment is likely to become the starting point for further accumulation. In the above configuration, the sediment accumulated in the internal space of the recess (61) where sedimentation is likely to occur can be cooled. Therefore, spontaneous combustion of the sediment can be suppressed more effectively, thereby improving the safety of the crusher.

[0083] Furthermore, in one aspect of the present disclosure, the crusher has a deposition section (60) that protrudes from the inner circumferential surface of the housing (11) and has a flow deflection plate (63) that deflects the flow of the conveying gas.

[0084] In the above configuration, the sediment accumulated on the flow deflection plate can be cooled. Therefore, spontaneous combustion of the sediment can be suppressed, thereby improving the safety of the crusher.

[0085] Furthermore, in one aspect of the present disclosure, the crusher has a plate-shaped plate portion (150) in the accumulation section (60) that extends along a horizontal plane from the inner circumferential surface of the housing (11) toward the center of the housing (11).

[0086] The inner surface of the enclosure is prone to wear because it is frequently struck by solid fuel being transported by the conveying gas and solid fuel ejected from the rotary classifier. In the above configuration, a plate-like section extending from the inner circumferential surface of the housing is provided as a deposit section. Deposits accumulate on the upper surface of the plate-like section. As a result, a portion of the inner circumferential surface of the housing is covered with deposits. This prevents direct contact between the inner circumferential surface of the housing and the solid fuel transported by the transport gas or the solid fuel ejected from the rotary classifier. Therefore, wear on the inner circumferential surface of the housing can be suppressed.

[0087] Furthermore, a crusher according to one aspect of the present disclosure includes a temperature detection unit (76) for detecting the temperature of the crushed solid fuel deposited in the deposit section (60), and controls whether or not the cooling unit (70) cools the crushed solid fuel based on the temperature detected by the temperature detection unit (76).

[0088] In the above configuration, the cooling unit controls whether or not to cool the sediment based on the temperature measured by the temperature measurement unit. This allows the sediment to be cooled according to its temperature. Therefore, the sediment can be cooled appropriately. For example, if the temperature of the crushed solid fuel is above a predetermined threshold, the crushed solid fuel may be cooled in the cooling unit, and if the temperature of the crushed solid fuel is below the predetermined threshold, the cooling unit may be stopped and the crushed solid fuel may not be cooled.

[0089] A power plant (1) according to one aspect of the present disclosure comprises a crusher (10) as described above, a boiler (200) that burns the solid fuel crushed by the crusher (10) to generate steam, and a power generation unit that generates electricity using the steam generated by the boiler (200).

[0090] A method for operating a pulverizer according to one aspect of the present disclosure comprises a housing (11) forming an outer shell, a pulverizing table (12) provided inside the housing (11) on which solid fuel is supplied to the upper surface, a pulverizing roller (13) for pulverizing the solid fuel on the pulverizing table (12), a conveying gas supply unit (30) for supplying conveying gas into the housing (11) to convey the solid fuel pulverized on the pulverizing table (12) to an outlet (19) provided in the housing (11), a deposit unit (60) on which the pulverized solid fuel is deposited, and a cooling unit (70) for cooling the pulverized solid fuel deposited in the deposit unit (60), wherein the angle of the upper surface of the deposit unit (60) with respect to the horizontal plane is less than or equal to the angle of repose of the solid fuel, and the method for operating a pulverizer (10) comprises a cooling step of cooling the pulverized solid fuel deposited in the deposit unit (60) by the cooling unit (70). [Explanation of symbols]

[0091] 1: Power plant 10: Mill (crusher) 11: Housing (enclosure) 12: Grinding Table 13: Crushing roller 14: Drive unit 15: Mill Motor 16: Rotary Classifier 16a: Blade 17:Fuel supply section 18: Classification motor 19: Exit port (exit section) 20:Coal feeding machine 21: Banka 22: Conveyor Unit 23: Coal feeder motor 24: Downspout 30: Blower unit 30a: Hot gas flow path 30b: Cold gas flow path 30c: Thermal gas damper 30d: Cold gas damper 31: Primary air ventilator 32: Forced ventilation fan 34:Heat exchanger 40: Condition of the damaged area 41: Bottom part 42: Ceiling 45: Journal head (support part) 47: Support arm 48: Support shaft 49: Pressing device 50: Control Unit 60: Deposition part 61: Recess 62: Roller cover (cover part) 63: Current plate 64: Bottom 70: Cooling section 71:Heat exchange section 72: First cooling water piping 73: Second cooling water piping 74: Heat dissipation part 75: Shut-off valve 76: Sediment temperature detection unit (temperature detection unit) 100: Solid fuel grinding machine 100a: Primary airflow channel 100b: Fine fuel supply channel 110: Cooling section 111: Cooling air piping 112: Injection part 113: Branch piping 120: Cooling section 121: Refrigerant piping 130: Cooling section 131: Bottom fin 132: Side fins 133: Cooling fan 140: Cooling section 141:Heat exchange section 142: Third cooling water piping 143: Fourth cooling water piping 150: Plate part 200: Boiler 210: Furnace 220: Burner

Claims

1. The outer shell is the casing, A crushing table is provided inside the aforementioned enclosure, with solid fuel supplied to its upper surface, A grinding roller for grinding the solid fuel on the grinding table, A conveying gas supply unit supplies conveying gas into the interior of the housing to transport the solid fuel, which has been crushed on the crushing table, to an outlet provided in the housing, On the upper surface, the angle with respect to the horizontal plane is less than or equal to the angle of repose of the solid fuel, and there is a deposit section for depositing the pulverized solid fuel, A cooling unit for cooling the solid fuel deposited in the aforementioned deposit section, Equipped with, The cooling unit is provided on at least a part of the deposit portion, or on at least a part of the housing in contact with the deposited solid fuel, and has a cooling surface and a heat dissipation surface, and is a crusher that dissipates heat by transferring heat absorbed from the cooling surface to the heat dissipation surface.

2. The crusher according to claim 1, wherein the cooling unit has a heat exchange unit or thermoelectric element to which cooling water is supplied, which is placed on the upper surface of the deposit unit inside the housing or is arranged outside the housing so as to be in contact with the lower surface of the deposit unit, or a plurality of lower fins protruding downward from the lower surface of the deposit unit, or a plurality of side fins protruding from the outer surface of the side wall of the housing that is in contact with the solid fuel.

3. The crusher according to claim 1, wherein the upper surface of the deposit portion is inclined with respect to a horizontal plane, and the amount of solid fuel deposited on the upper surface of the deposit portion is adjusted compared to the case where the upper surface of the deposit portion is a horizontal plane.

4. A support portion that supports the aforementioned crushing roller on the housing, It comprises a recess for accommodating the support portion, The crusher according to claim 1, wherein the deposit portion is located in the internal space of the recess.

5. The crusher according to claim 1, wherein the accumulation section has a flow deflection plate that protrudes from the inner circumferential surface of the housing and deflects the flow of the conveying gas.

6. The crusher according to claim 1, wherein the accumulation portion has a plate-shaped plate portion that extends along a horizontal plane from the inner circumferential surface of the housing toward the center of the housing.

7. The deposit section includes a temperature detection unit for detecting the temperature of the crushed solid fuel deposited therein. The pulverizer according to claim 1, wherein the cooling unit controls whether or not to cool the pulverized solid fuel based on the temperature detected by the temperature detection unit.

8. A pulverizer according to any one of claims 1 to 7, A boiler that burns the solid fuel crushed by the aforementioned crusher to generate steam, A power plant comprising: a power generation unit that generates electricity using the steam produced by the boiler;

9. The outer shell is the casing, A crushing table is provided inside the aforementioned enclosure, with solid fuel supplied to its upper surface, A grinding roller for grinding the solid fuel on the grinding table, A conveying gas supply unit supplies conveying gas into the interior of the housing to transport the solid fuel, which has been crushed on the crushing table, to an outlet provided in the housing, On the upper surface, the angle with respect to the horizontal plane is less than or equal to the angle of repose of the solid fuel, and there is a deposit section for depositing the pulverized solid fuel, The system comprises a cooling unit for cooling the solid fuel deposited in the aforementioned deposit section, The cooling unit is provided on at least a part of the deposit portion or on at least a part of the housing in contact with the deposited solid fuel, and has a cooling surface and a heat dissipation surface, and the method of operating a crusher involves transferring heat absorbed from the cooling surface to the heat dissipation surface to dissipate heat, A method for operating a crusher, comprising a cooling step of cooling the solid fuel deposited in the deposit section with the cooling section.

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