Crusher and power generation plant, and method for operating the crusher

Abstract

To change a rotational speed of a crushing table using a simple structure.SOLUTION: A mill includes: a rotating crushing table having a top face to which a solid fuel is supplied; a crushing roller for crushing the solid fuel by pressing the solid fuel to the crushing table; a motor for generating drive power for rotating the crushing table; and a reduction gear 14 for transmitting the drive power of the motor to the crushing table. The reduction gear 14 includes a deceleration part 80 using a speed reduction ratio changing mechanism 90 capable of changing a speed reduction ratio and a planetary gear mechanism.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a pulverizer and power plant, as well as a method of operating the pulverizer. [Background technology]

[0002] Conventionally, solid fuels (carbon-containing solid fuels) such as coal and biomass fuels are pulverized into fine powder within a predetermined particle size range by a pulverizer (mill) and then supplied to a combustion device. In the mill, solid fuels such as coal and biomass fuels fed to a pulverizing table are pinched between the pulverizing table and a pulverizing roller to pulverize them, and fine fuels within a predetermined particle size range are selected by a classifier from the pulverized solid fuels that have been pulverized by a conveying gas (primary air) supplied from the outer periphery of the pulverizing table, and then transported to a boiler and combusted in a combustion device. In a thermal power plant, steam is generated by heat exchange with the combustion gas generated by burning the pulverized fuel in the boiler, and the steam is used to rotate and drive a steam turbine, which then rotates and drives a generator connected to the steam turbine to generate electricity.

[0003] The rotational force of the grinding table of the mill is generated by a motor. The rotational force generated by the motor is converted to a rotational speed and rotational torque suitable for grinding via a reducer, and then transmitted to the grinding table. In addition, for example, the rotational shaft of the motor may extend horizontally, and the rotational shaft of the grinding table may extend vertically. In this way, when the extension direction of the rotational shaft of the motor and the extension direction of the rotational shaft of the grinding table differ, the rotational direction is also changed by the reducer. A known example of a mill equipped with such a reduction gear is the mill disclosed in Patent Document 1. Patent Document 1 discloses a mill using a planetary gear reduction gear as the reduction gear for driving the pulverizer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-118392 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, as the introduction of power generation facilities using renewable energy such as solar power generation has progressed, thermal power generation facilities are required to improve the load change speed in order to absorb the difference in the amount of power supplied by solar power generation during the day and at night. Mills that supply fuel are also required to respond to the improvement in the load change speed. At the same time, the fuels used in thermal power generation facilities are also diversifying, and there is an increasing need to use low-grade coal (sub-bituminous coal, lignite, etc.) and biomass fuel instead of conventional bituminous coal, so there is a demand for mills that can easily change the grinding capacity according to requirements.

[0006] Here, in order to change the grinding capacity of the mill, it is possible to change the rotation speed of the grinding table. By changing the rotation speed of the grinding table, it is possible to widen the operable range of the mill compared to the conventional case. If the operable range of the mill is widened, for example, by reducing the rotation speed of the grinding table and enabling the mill to be operated at a lower load, it is possible to eliminate the time required to switch the number of mills in operation when the load changes, thereby shortening the load change time, or conversely, by increasing the rotation speed of the grinding table, it becomes possible to grind fuels that are difficult to grind.

[0007] As a method for changing the rotation speed of the grinding table, it is possible to use an inverter or pole change motor to make the motor rotation speed variable. However, the method of using an inverter or pole change motor requires a corresponding motor and electrical equipment, which makes the structure complicated and increases the introduction cost. In addition, when increasing the rotation speed of the grinding table, the power consumption increases, so the capacity of the motor and electrical equipment must also be increased. Therefore, it has been desired to change the rotation speed of the grinding table to a desired rotation speed with a simple structure without increasing the power consumption.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to provide a crusher, a power generation plant, and a method for operating a crusher that can change the rotation speed of the crushing table with a simple structure without increasing power consumption. [Means for solving the problem]

[0009] In order to solve the above problems, the pulverizer, power generation plant, and pulverizer operating method of the present disclosure employ the following measures. A crusher according to one embodiment of the present disclosure includes a crushing table that rotates with solid fuel supplied to its upper surface, a crushing roller that presses the solid fuel against the crushing table to crush the solid fuel, a motor that generates a driving force to rotate the crushing table, and a reducer that transmits the driving force of the motor to the crushing table, and the reducer has a reduction ratio change mechanism that can change the reduction ratio and a reduction section that uses a planetary gear mechanism.

[0010] A method of operating a crusher according to one aspect of the present disclosure is a method of operating a crusher that crushes solid fuel, the crusher comprising: a crushing table that rotates with the solid fuel supplied to its upper surface; a crushing roller that presses the solid fuel against the crushing table to crush the solid fuel; a motor that generates a driving force to rotate the crushing table; and a reducer that transmits the driving force of the motor to the crushing table, the reducer having a reduction ratio change mechanism capable of changing the reduction ratio and a reduction section using a planetary gear mechanism, and the method includes a step of changing the reduction ratio of the reducer using the reduction ratio change mechanism. Effect of the Invention

[0011] According to the present disclosure, the rotation speed of the grinding table can be changed with a simple structure. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a configuration diagram showing a solid fuel pulverizer and a boiler according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a perspective view showing a reducer according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a schematic exploded front view showing a reducer according to an embodiment of the present disclosure. [Figure 4] 5A to 5C are schematic diagrams illustrating a method for replacing a reducer according to an embodiment of the present disclosure. [Diagram 5] 1A and 1B are schematic plan views showing a gear ratio change mechanism provided in a reducer according to an embodiment of the present disclosure, in which (a) and (b) show the case where there is an even number of gears, and (c) and (d) show the case where there is an odd number of gears. [Figure 6] 1 is a graph showing a change in output of a power plant according to an embodiment of the present disclosure. [Figure 7] FIG. 11 is a schematic front view showing a reducer according to a modified example of the embodiment of the present disclosure. [Figure 8] FIG. [Figure 9] FIG. 1 is a perspective view showing a conventional planetary reducer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of a pulverizer, a power plant, and a pulverizer operation method according to the present disclosure will be described with reference to the drawings. A power plant 1 according to this embodiment includes a solid fuel pulverizer 100 and a boiler 200. In the following explanation, "upper" refers to the vertically upper direction, and "upper" in terms such as upper part and upper surface refers to the vertically upper part. Similarly, "lower" refers to the vertically lower part, and the vertical direction is not precise and may include errors.

[0014] The solid fuel pulverizer 100 of this embodiment is an apparatus that pulverizes solid fuel (carbon-containing solid fuel) such as coal or biomass fuel, generates pulverized fuel, and supplies it to a burner (combustion device) 220 of a boiler 200. The power plant 1 including the solid fuel pulverizer 100 and the boiler 200 shown in FIG. 1 is equipped with one solid fuel pulverizer 100, but it may also be a system equipped with multiple solid fuel pulverizers 100 corresponding to each of the multiple burners 220 of one boiler 200.

[0015] The solid fuel pulverizing device 100 of this embodiment includes a mill (pulverizer) 10, a coal feeder (fuel supplier) 20, a blower (carrier gas supplier) 30, a state detector 40, and a controller (determiner) 50.

[0016] The mill 10, which pulverizes solid fuel such as coal or biomass fuel to be supplied to the boiler 200 into fine fuel, which is a finely powdered solid fuel, may be of a type that pulverizes only coal, may be of a type that pulverizes only biomass fuel, or may be of a type that pulverizes biomass fuel together with coal. Here, biomass fuels are organic resources derived from renewable living organisms, such as thinned wood, waste wood, driftwood, grass, waste, sludge, tires, and recycled fuels (pellets and chips) made from these materials, but are not limited to the ones presented here.Biomass fuels are carbon neutral, meaning they do not emit carbon dioxide, a greenhouse gas, because they capture carbon dioxide during the biomass growth process, and various uses for them are being considered.

[0017] For example, a plurality of the same type of mills 10 are installed. When the load change range (change range of fuel supply amount) required for the power plant 1 exceeds the range of fuel supply amount that can be stably operated for each mill 10 (turndown of the mill 10), the number of mills 10 in operation is switched. In other words, the number of mills 10 in operation is switched to change the amount of fuel supplied to the boiler 200 so that the generator can generate the electric power required for the power plant 1. The mill 10 comprises a housing 11, a grinding table (rotary table) 12, grinding rollers 13, a reducer 14, a motor 15 connected to the reducer 14 for driving and rotating the grinding table 12, a rotary classifier 16, a fuel supply unit 17, and a classifier motor 18 for driving and rotating the rotary classifier 16. The housing 11 is formed in a cylindrical shape extending in the vertical direction, and is a case that accommodates the grinding table 12, the grinding rollers 13, the rotary classifier 16, and the fuel supply unit 17. A fuel supply unit 17 is attached to the center of the ceiling portion 42 of the housing 11. This fuel supply unit 17 supplies solid fuel guided from the bunker 21 into the housing 11, and is disposed in the vertical direction at the center position of the housing 11 with its lower end extending into the interior of the housing 11.

[0018] A reduction gear 14 is installed near the bottom surface 41 of the housing 11, and the grinding table 12 is rotatably arranged to rotate by the driving force transmitted from a motor 15 connected to the reduction gear 14. The grinding table 12 is rotatably arranged around a central axis C1. The grinding table 12 is a circular member in a plan view, and is disposed so that the lower end of the fuel supply unit 17 faces it. The upper surface of the grinding table 12 may have an inclined shape that is low in the center and high toward the outside, and the outer periphery may have a shape that is curved upward. The fuel supply unit 17 supplies solid fuel (for example, coal or biomass fuel in this embodiment) from above toward the grinding table 12 below, and the grinding table 12 grinds the supplied solid fuel between the grinding roller 13.

[0019] When solid fuel is fed from the fuel supply unit 17 toward the approximate center region of the grinding table 12, the centrifugal force generated by the rotation of the grinding table 12 guides the solid fuel to the outer periphery of the grinding table 12, where it is pinched and pulverized between the grinding table 12 and the grinding rollers 13. The pulverized solid fuel is blown upward by the carrier gas (hereinafter referred to as primary air) guided from the carrier gas passage (hereinafter referred to as primary air passage) 100a, and is guided to the rotary classifier 16. An outlet (not shown) is provided on the outer periphery of the grinding table 12, through which the primary air flowing in from the primary air passage 100a flows out into the space above the grinding table 12 in the housing 11. A swirling blade (not shown) is provided 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 having a swirling velocity component, and conveys the solid fuel pulverized on the grinding table 12 to the rotary classifier 16 located at the upper part in the housing 11. Among the pulverized solid fuel, particles larger than a predetermined particle size are classified by the rotary classifier 16, or fall without reaching the rotary classifier 16, are returned to the grinding table 12, and are pulverized again between the grinding table 12 and the grinding roller 13.

[0020] The crushing roller 13 is a rotating body that crushes the solid fuel supplied onto the crushing table 12 from the fuel supply unit 17. The crushing roller 13 is pressed against the upper surface of the crushing table 12 and cooperates with the crushing table 12 to crush the solid fuel. 1 shows only one representative crushing roller 13, but multiple crushing rollers 13 are arranged at regular intervals in the circumferential direction so as to press against the upper surface of the crushing table 12. For example, three crushing rollers 13 are arranged at equal intervals in the circumferential direction on the outer periphery at angular intervals of 120°. In this case, the portions where the three crushing rollers 13 come into contact with the upper surface of the crushing table 12 (pressing portions) are equidistant from the rotation center axis of the crushing table 12.

[0021] The crushing roller 13 can swing up and down by the journal head 45, and is supported so as to be able to move toward and away from the upper surface of the crushing table 12. When the crushing table 12 rotates with the outer circumferential surface of the crushing roller 13 in contact with the solid fuel on the upper surface of the crushing table 12, the crushing roller 13 receives a rotational force from the crushing table 12 and rotates with the crushing table 12. When solid fuel is supplied from the fuel supply unit 17, the solid fuel is pressed between the crushing roller 13 and the crushing table 12 and crushed.

[0022] A support arm 47 of the journal head 45 is supported on the side of the housing 11 by a support shaft 48 whose middle portion is aligned horizontally so that the crushing roller 13 can swing up and down about the support shaft 48. A pressing device 49 is provided on the upper end portion on the vertically upper side of 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 etc. so as to press the crushing roller 13 against the crushing table 12.

[0023] The reducer 14 is a device that transmits a driving force to the grinding table 12 and rotates the grinding table 12 around the central axis. The reducer 14 is connected to the motor 15 and transmits the driving force of the motor 15 to the grinding table 12. Details of the reducer 14 will be described later.

[0024] The rotary classifier 16 is provided at the top of the housing 11 and has a hollow, generally inverted cone-shaped exterior. The rotary classifier 16 is provided with a plurality of blades 16a extending in the vertical direction at its outer periphery. The blades 16a are provided at predetermined intervals (equally spaced) around the central axis of the rotary classifier 16. The rotary classifier 16 is a device that classifies the solid fuel (hereinafter, the pulverized solid fuel is referred to as "pulverized fuel") pulverized by the pulverizing table 12 and the pulverizing rollers 13 into fuel having a particle size larger than a predetermined particle size (for example, 70 to 100 μm for coal) (hereinafter, the pulverized fuel having a particle size larger than the predetermined particle size is referred to as "coarse pulverized fuel") and fuel having a particle size smaller than the predetermined particle size (hereinafter, the pulverized fuel having a particle size smaller than the predetermined particle size is referred to as "fine pulverized fuel"). The rotary classifier 16 that classifies by rotation is also called a rotary separator, and is given a rotational driving force by a classifier motor 18 controlled by the control unit 50, and rotates around the fuel supply unit 17 centering on a cylindrical axis (not shown) extending in the vertical direction of the housing 11. The classifier may be a fixed classifier having a fixed hollow inverted cone-shaped casing and a plurality of fixed swirling vanes on the outer periphery of the casing instead of the blades 16a.

[0025] When the pulverized fuel reaches the rotary classifier 16, due to the relative balance between the centrifugal force generated by the rotation of the blades 16a and the centripetal force of the primary air flow, large diameter coarse pulverized fuel particles are knocked down by the blades 16a and returned to the pulverizing table 12 to be pulverized again, and the fine pulverized fuel is guided to the outlet port 19 in the ceiling 42 of the housing 11. The fine pulverized fuel classified by the rotary classifier 16 is discharged from the outlet port 19 to the pulverized fuel supply passage 100b together with the primary air, and is supplied to the burner 220 of the boiler 200. When the solid fuel is coal, the pulverized fuel supply passage 100b is also called a pulverized coal pipe.

[0026] The fuel supply unit 17 is attached so that its lower end portion extends vertically into the interior of the housing 11 so as to penetrate the ceiling portion 42 of the housing 11, and supplies solid fuel input from the upper portion of the fuel supply unit 17 to the approximately central region of the grinding table 12. The fuel supply unit 17 is supplied with solid fuel from the coal feeder 20.

[0027] The coal feeder 20 includes a conveying unit 22 and a coal feeder motor 23. The conveying unit 22 is, for example, a belt conveyor, and conveys the solid fuel discharged from the lower end of the downspout 24 located directly below the bunker 21 to the top of the fuel supply unit 17 of the mill 10 by the driving force provided by the coal feeder motor 23, and inputs the solid fuel into the fuel supply unit 17. Normally, primary air is supplied to the inside of the mill 10 to transport pulverized fuel to the burner 220, and the pressure therein is higher than that of the coal feeder 20 and the bunker 21. The downspout 24, which is a pipe extending in the vertical direction directly below the bunker 21, holds fuel in a layered state inside, and the solid fuel layers layered inside the downspout 24 ensure a seal that prevents the primary air and pulverized fuel on the mill 10 side from flowing back to the bunker 21 side. The amount of solid fuel supplied to the mill 10 is adjusted by, for example, the moving speed of the belt conveyor of the transport unit 22.

[0028] The blower 30 is a device that blows primary air into the housing 11 to dry the pulverized fuel and to transport it to the rotary classifier 16 . In order to appropriately adjust the flow rate and temperature of the primary air blown into the housing 11, in this embodiment, the blower section 30 is equipped with a primary air fan (PAF) 31, a hot gas flow path 30a, a cold gas flow path 30b, a hot gas damper 30c, and a cold gas damper 30d.

[0029] In this embodiment, the hot gas flow path 30a supplies a part of the air (outside air) sent out from the primary air fan 31 as hot gas heated by passing 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 flow rate of the hot gas supplied from the hot gas flow path 30a is determined by the opening degree of the hot gas damper 30c.

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

[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 flow path 30a and the flow rate of the cold gas supplied from the cold gas flow path 30b, and the temperature of the primary air is determined by the mixing ratio of the hot gas supplied from the hot gas flow path 30a and the cold gas supplied from the cold gas flow path 30b, and is controlled by the control unit 50. In addition, the oxygen concentration of the primary air blown from the primary air passage 100a to the inside of the housing 11 may be adjusted by introducing a portion of the combustion gas discharged from the boiler 200 via a gas recirculation fan (not shown) into the hot gas supplied from the hot gas passage 30a and mixing it.

[0032] In this embodiment, the state detection unit 40 of the mill 10 transmits measured or detected data to the control unit 50. The state detection unit 40 of this embodiment is, for example, a differential pressure measurement means, and measures the differential pressure of the mill 10 as the pressure difference between the pressure at the portion where the primary air flows into the inside of the housing 11 from the primary air flow passage 100a and the pressure at the outlet port 19 where the primary air and the pulverized fuel are discharged from the inside of the housing 11 to the pulverized fuel supply flow passage 100b. An increase or decrease in this differential pressure of the mill 10 corresponds to an increase or decrease in the amount of pulverized fuel circulating between the vicinity of the rotary classifier 16 inside the housing 11 and the vicinity of the grinding table 12 due to the classification effect of the rotary classifier 16. In other words, by adjusting the rotation speed of the rotary classifier 16 in accordance with the pressure difference at the mill 10, the amount of pulverized fuel discharged from the outlet port 19 can be adjusted in relation to the amount of solid fuel supplied to the mill 10.Therefore, within the range in which the particle size of the pulverized fuel does not affect the combustibility of the burner 220, an amount of pulverized fuel corresponding to the amount of solid fuel supplied to the mill 10 can be stably supplied to the burner 220 provided in the boiler 200. The state detection unit 40 in this embodiment is, for example, a temperature measuring means, which detects the temperature of the primary air supplied to the inside of the housing 11 (the 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 blower unit 30 so that the upper limit temperature is not exceeded. The upper limit temperature is determined taking into consideration the possibility of ignition of the solid fuel, etc. The primary air is cooled inside the housing 11 by transporting the pulverized fuel while drying it, 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 pulverization apparatus 100 . 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 to adjust the classification performance, and optimizes the differential pressure of the mill 10, i.e., the amount of pulverized fuel circulating inside the mill 10, within a predetermined range, thereby enabling a stable supply of pulverized fuel to the burner 220. Furthermore, the control unit 50 can adjust the supply amount (coal supply amount) of solid fuel that the transport unit 22 transports and supplies to the fuel supply unit 17 by, for example, transmitting a drive command to the coal feeder motor 23 of the coal feeder 20. The range of solid fuel supply amount that allows each mill 10 to stably operate is determined by the rated crushing capacity of the mill 10 (the processable amount that allows a predetermined solid fuel to be crushed to a predetermined particle size range), and is about 30% to 100% when the rated crushing capacity is taken as 100%. Note that, in mills of the same specifications, the rated crushing capacity of the mill 10 increases as the rotation speed of the crushing table 12 increases. In addition, if the range of change in the solid fuel supply amount corresponding to the load change required of the power generation plant 1 exceeds the range that each mill 10 can handle, the control unit 50 starts or stops one of the mills 10 and changes the number of mills 10 in operation. 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 become predetermined values ​​set in accordance with the amount of coal feed for each type of solid fuel.

[0034] The control unit 50 is composed of, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, and the CPU reads the program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, may be provided in a state stored in a computer-readable storage medium, or may be distributed via a wired or wireless communication means. The computer-readable storage medium may be a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. The HDD may be replaced with a solid state disk (SSD) or the like.

[0035] Next, a description will be given of the boiler 200 which generates steam by performing combustion using the pulverized fuel supplied from the solid fuel pulverizer 100. The boiler 200 includes a furnace 210 and a burner 220.

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

[0037] The combustion gas discharged from the boiler 200 undergoes a predetermined treatment in an environmental device (such as a denitration device or an electric dust collector, not shown), and then undergoes heat exchange between the air discharged from the primary air fan 31 and the air discharged from the forced draft fan 32 in a heat exchanger 34, such as an air preheater, and is then guided to a chimney (not shown) via an induced draft fan (IDF) 33 and released into the outside air. The air discharged from the primary air fan 31, heated by the combustion gas in the heat exchanger 34, is supplied to the above-mentioned hot gas flow path 30a. The water supplied to each heat exchanger of boiler 200 is heated in a coal economizer (not shown), and then further heated by an evaporator (not shown) and a superheater (not shown) to generate high-temperature, high-pressure steam. This is then sent to the power generation section, a steam turbine (not shown), to rotate the steam turbine, which in turn rotates a generator (not shown) connected to the steam turbine to generate electricity, thereby constituting power generation plant 1.

[0038] Next, the reducer 14 according to this embodiment will be described in detail with reference to FIGS.

[0039] [Reducer 14 structure] The structure of the reducer 14 will be described. As shown in Figures 2 and 3, the reducer 14 has a reducer housing 60 that forms an outer shell, an output table 70, a reduction section 80 housed in the reducer housing 60, and a reduction ratio change mechanism 90 housed in the reducer housing 60.

[0040] The reducer housing 60 has a space formed therein. The space formed therein (hereinafter referred to as the "internal space") accommodates the reduction unit 80 and the reduction ratio change mechanism 90. The reducer housing 60 has an upper surface portion 61 that defines the upper side of the internal space, a lower surface portion 62 that defines the lower side of the internal space, and a side wall portion 63 that defines the side of the internal space. A table shaft portion 72 of the output table 70 penetrates the center of the upper surface portion 61. The upper surface portion 61 is configured to have higher strength than the side wall portion 63 and the lower surface portion 62 because a crushing load is transmitted to the upper surface portion 61 as described later. Specifically, the upper surface portion 61 is formed to have a thicker plate thickness.

[0041] The reducer housing 60 is fixed to the housing 11 of the mill 10. In detail, the upper surface portion 61 is fixed to a partition wall portion 65 (see FIG. 1) of the housing 11 by a plurality of connecting bolts 66 (fixing portions). The multiple connecting bolts 66 are arranged on the upper surface portion 61 so as to surround the table shaft portion 72. The partition wall 65 is a plate-like member extending along a substantially horizontal plane. The partition wall 65 separates a space in which the grinding table 12 and the like are housed from a space in which the main part of the reducer 14 is housed. An opening penetrating in the vertical direction is formed in the substantially center of the partition wall 65 (see FIG. 4). Note that FIG. 4 shows a state in which a worm reducer is provided as an existing reducer in the mill 10, for example, but the reducer 14 according to this embodiment is also provided in the mill 10 in the same manner as the existing reducer. That is, as shown in FIG. 4, the upper part of the reducer 14 (output table 70, etc.) is inserted through the opening.

[0042] In this manner, the reducer 14 according to this embodiment is fixed to the housing 11 of the mill 10. In other words, the reducer 14 is not fixed to a foundation (such as the ground). The specifications of the upper surface portion 61 and the connecting bolts 66 are preferably designed to withstand the expected crushing load and rotational torque.

[0043] The output table 70 has a substantially circular plate-shaped table portion 71 and a cylindrical table shaft portion 72 extending downward from the lower surface of the table portion 71. The output table 70 rotates clockwise in a top view around a central axis C1 along the vertical direction by a rotational driving force from the motor 15 transmitted via a speed reducer 80 or the like. That is, the output table 70 and the grinding table 12 rotate so that their central axes are coaxial. The table portion 71 of the output table 70 and the grinding table 12 are restricted in relative movement by a transmission portion (not shown) or the like. That is, when the output table 70 rotates, the grinding table 12 also rotates via the transmission portion. An example of the transmission portion is a plurality of bolts.

[0044] As shown in Fig. 3, a thrust bearing 74 is provided on the underside of the table portion 71 of the output table 70. The lower end of the thrust bearing 74 is provided on the upper surface of the upper surface portion 61 of the reducer housing 60. Therefore, the grinding load applied from the grinding table 12 is transmitted to the reducer housing 60 (more specifically, the upper surface portion 61) via the thrust bearing 74. The load transmitted to the reducer housing 60 is transmitted to the housing 11 of the mill 10 via the fixed portion. In this way, since crushing loads and the like act on the top surface portion 61, it is designed to be strong as described above. On the other hand, since the crushing load is not applied to the reducer housing 60 other than the top surface portion 61, the strength may be reduced. However, since the weight and rotational torque are applied, it is designed to have a strength capable of withstanding them.

[0045] The reduction gear unit 80 is a so-called planetary gear mechanism. The reduction gear unit 80 includes a sun gear 81, a plurality of planetary gears 82 (three in this embodiment as an example) that mesh with the sun gear 81, an internal gear 83, a planetary frame 84, and bearings (not shown). As shown in Fig. 3, the sun gear 81 is coaxially connected to an output spur gear 91 of the reduction ratio change mechanism 90 by a connecting shaft portion 85. As shown in Fig. 2, the planetary frame 84 is fixed to the table shaft portion 72 of the output table 70. In the speed reduction section 80, the rotation of a sun gear 81 is transmitted to planetary gears 82 rotatably held in a planetary frame 84, and orbital motion of the multiple planetary gears 82 is generated within a fixed internal gear 83, and this orbital motion is output from the planetary frame 84, thereby achieving high speed reduction with high efficiency. The sun gear 81 is fixed to a connecting shaft section 85 via a coupling or the like so as to allow some movement, and is structured so that the load on the planetary gears 82 is evenly distributed by automatically changing its position according to the load on the multiple planetary gears 82.

[0046] As shown in Figs. 2 and 3, the reduction ratio change mechanism 90 is composed of a plurality of (four in this embodiment as an example) spur gears (reduction ratio change gears). Specifically, the reduction ratio change mechanism 90 has an output spur gear 91 fixed to the sun gear 81 via a connecting shaft portion 85, an input spur gear 92 meshing with an input shaft 99 of the motor 15 via a bevel gear, and a first spur gear 93 and a second spur gear 94 provided between the output spur gear 91 and the input spur gear 92. The output spur gear 91, the input spur gear 92, the first spur gear 93 and the second spur gear 94 are arranged such that the central axes of the gears are aligned in a straight line. The gears constituting the reduction ratio change mechanism 90 are not limited to spur gears. For example, they may be helical gears.

[0047] 3, the output spur gear 91 is provided coaxially with the sun gear 81 and the connecting shaft portion 85. That is, the output spur gear 91 is supported by the reducer housing 60 via an output bearing 91a so as to be rotatable about the central axis C1.

[0048] The first spur gear 93 meshes with the input spur gear 92 and the second spur gear 94. The first spur gear 93 is supported by the reducer housing 60 by a first bearing 93a so as to be rotatable about a central axis C2 that extends in the up-down direction.

[0049] The second spur gear 94 meshes with the first spur gear 93 and the output spur gear 91. The second spur gear 94 is supported by the reducer housing 60 by a second bearing 94a so as to be rotatable about a central axis C3 that extends in the up-down direction.

[0050] The input spur gear 92 meshes with the first spur gear 93. The input spur gear 92 is supported by the reducer housing 60 via an input bearing 92a so as to be rotatable about a central axis C4 extending in the vertical direction. A reducer bevel gear 96 is fixed to the upper surface of the input spur gear 92. The reducer bevel gear 96 meshes with a motor bevel gear 97 provided at the tip of an input shaft 99 of the motor 15.

[0051] 2, the input shaft 99 of the motor 15 is supported so as to be rotatable about a central axis C5 extending in the horizontal direction. The input shaft 99 of the motor 15 is supported by a motor input bearing 99a. In this manner, the reducer-side bevel gear 96 and the motor-side bevel gear 97 convert the direction of the rotational motion (horizontal axis direction) from the motor 15 to the vertical axis direction, and transmit it to the rear stage.

[0052] 2, the direction in which the central axis C5 of the input shaft 99 of the motor 15 extends does not intersect with the direction in which the central axis C1 of the grinding table 12 extends. In other words, the central axis C5 of the input shaft 99 of the motor 15 and the central axis C1 of the grinding table 12 are in a twisted relationship.

[0053] The numbers of teeth of the output spur gear 91, the input spur gear 92, the first spur gear 93, and the second spur gear 94 are determined so as to obtain a target reduction ratio. That is, the numbers of teeth of each spur gear are determined in consideration of the reduction ratio of the reduction unit 80 so that the rotation speed of the grinding table 12 becomes the desired rotation speed. The reduction ratio of the reduction ratio change mechanism 90 is determined by the ratio between the number of teeth of the input spur gear 92 and the number of teeth of the output spur gear 91.

[0054] Therefore, for example, when it is desired to set the reduction ratio of the reduction ratio change mechanism 90 to 1:1 (i.e. when it is desired to make the rotation speed of the motor 15 and the input rotation speed of the reduction unit 80 the same), the diameter of the input spur gear 92 and the diameter of the output spur gear 91 are made the same length, and the number of teeth of the input spur gear 92 and the number of teeth of the output spur gear 91 are made the same, as shown in Figure 5(a). In this case, the diameters and numbers of teeth of the first spur gear 93 and the second spur gear 94 are also the same as those of the input spur gear 92 and the output spur gear 91.

[0055] Furthermore, for example, if it is desired to set the reduction ratio of the reduction ratio change mechanism 90 to 3:1 (i.e., to set the input rotational speed of the reduction unit 80 to 1 / 3 the rotational speed of the motor 15), the diameter of the output spur gear 91 is set to three times the diameter of the input spur gear 92, and the number of teeth of the output spur gear 91 is set to three times the number of teeth of the input spur gear 92, as shown in Figure 5(b). In this case, the diameter and number of teeth of the first spur gear 93 are the same as those of the output spur gear 91. Also, the diameter and number of teeth of the second spur gear 94 are the same as those of the input spur gear 92.

[0056] The reducer 14 also includes a lubricating oil device (not shown) that distributes and supplies a sufficient amount of lubricating oil to each component, such as the reduction unit 80 and the reduction ratio change mechanism 90. Note that, instead of providing a new lubricating oil device, lubricating oil may be supplied to each component from a lubricating oil device provided in the mill 10. A measuring device (not shown) is also incorporated in the reducer 14. The measuring device is, for example, a sensor or field instrument for detecting the temperature of each bearing or tank, as well as the pressure or vibration of each part. It is also preferable to install a sight flow to check the flow of lubricating oil in the lubricating oil pipes connected to each part of the reducer 14.

[0057] [How to replace the reducer] Next, a method for replacing the reducer will be described with reference to FIG. In this disclosure, a method of replacing a worm reducer 101 equipped with a transmission / reduction mechanism using a worm gear that is already installed on a mill 10 with a reducer 14 according to this embodiment will be described. The existing worm reducer 101 is a so-called hanging type reducer that is fixed so as to be hung from the housing 11 of the mill 10.

[0058] The work to replace the reducer is carried out in the following order: disconnection of the existing worm reducer 101, lifting it down and carrying it out, and then carrying in the new reducer 14, lifting it up, and connecting it. First, the mill 10 is disconnected from the existing worm reducer 101. When disconnecting the connection, first, the lubricating oil inside the existing worm reducer 101 is removed. Next, the motor coupling, lubricating oil piping, instrumentation piping, electrical wiring, etc. are removed. Next, the bolts connecting the grinding table 12 and the output table 70 of the worm reducer 101 are removed, and the worm reducer 101 is left hanging from the mill 10 by only the connecting bolts 66.

[0059] Next, as shown in Fig. 4, the bottom surface of the worm reduction gear 101 is supported by a jack 104. With the worm reduction gear 101 supported by the jack 104, the connecting bolts 66 connecting the housing 11 of the mill 10 and the reducer housing of the worm reduction gear 101 are removed, and the worm reduction gear 101 is suspended and lowered by the jack 104. At this time, a dolly 103 or the like is installed on the bottom surface portion 41 of the housing 11 below the worm reduction gear 101, and the worm reduction gear 101 is suspended and lowered so as to be placed on the dolly 103. Note that instead of supporting the jack 104, the worm reduction gear 101 may be suspended and lowered from the housing 11 of the mill 10 using a chain block, a hanging bolt, or the like. After the worm reduction gear 101 is placed on the dolly 103, the jack 104 is removed.

[0060] Next, as shown by the dashed line in Figure 4, the worm reduction gear 101 on the cart 103 is pulled horizontally with a lever block (registered trademark) or the like, and the existing worm reduction gear 101 is carried out from the mill 10. At this time, to prevent the worm reduction gear 101 from running away, it is advisable to also provide a chain block or the like in the opposite direction to the traveling direction of the worm reduction gear 101, and gradually loosen the chain block in the opposite direction to the traveling direction while pulling it with the chain block in the traveling direction. In this way, the existing worm reduction gear 101 is removed.

[0061] After the removal of the existing worm reduction gear 101 is completed, a new reduction gear (the reduction gear 14) is installed. The installation work of the reduction gear 14 is performed by reversing the procedure of the removal work described above. That is, first, the reducer 14 placed on a cart 103 is carried into the mill 10. Next, it is lifted up with a jack 104 or the like, and the housing 11 of the mill 10 and the reducer housing 60 are connected with connecting bolts 66, leaving the reducer 14 in a suspended state. Next, the grinding table 12 and the output table 70 of the reducer 14 are connected with bolts. Next, the motor coupling is attached, the lubricating oil piping is connected, and the mill 10 and the reducer 14 are connected. In this manner, the new reducer 14 is installed on the mill 10.

[0062] When replacing with a new reducer 14, it is preferable that the specifications of the upper surface 61 of the reducer housing 60 and the connecting bolts 66 are designed in the same manner as the existing worm reducer 101, and that they are designed to withstand the same crushing load and rotational torque as the existing worm reducer 101. However, the material of the connecting bolts 66 may be improved, the number of connecting bolts 66 may be increased, or a member (e.g., a key or a pin) may be added to fix the housing 11 of the mill 10 to the reducer housing 60 other than the connecting bolts 66. In this way, the fixing between the housing 11 and the reducer 14 can be made stronger. In addition, it is preferable that the fixing between the grinding table and the output table 70 of the reducer 14 is designed in the same manner as the existing worm reducer 101, and that they are designed to withstand the same crushing load and rotational torque as the existing worm reducer 101. Of course, the material of the bolts may be improved.

[0063] In addition, the reducer 14 has better transmission efficiency than the worm reducer 101. For this reason, by replacing it with the reducer 14, the amount of heat generated by the bearing itself tends to decrease, so that cooling can be sufficiently performed even with the existing lubrication device, but when changing the thrust bearing 74 from a dynamic pressure type in which oil is drawn to the sliding surface by the movement of the rotor and an oil film is formed, to a static pressure type in which oil is forcibly sent to the sliding surface by a high-pressure pump and an oil film is formed, a new high-pressure line may be installed or the like for modification. It is also desirable that each bearing provided in the reducer 14 is newly designed to be of a size capable of adequately supporting the reaction force from each supported rotating shaft and to have a sufficient life for the rotation speed. It is also desirable that the thrust bearing 74, which receives the crushing load from the grinding table 12, has a load-bearing specification equal to or greater than that of the thrust bearing 74 provided in the existing worm reducer 101.

[0064] The removed reducer (existing worm reducer 101) may be stored as a spare reducer. The reducer (reduction gear 14) according to this embodiment is attached to the housing 11 in the same manner as the reducer (existing worm reducer 101) before replacement. Generally, the worm reducer 101 does not intersect with the direction in which the central axis of the input shaft 99 of the motor 15 extends and with the direction in which the central axis of the grinding table extends. The reducer 14 of this embodiment also does not intersect with the direction in which the input shaft 99 of the motor 15 and the central axis C5 extend and with the direction in which the central axis C1 of the grinding table 12 extends. For this reason, by storing the old worm reducer 101, if a problem occurs with the replaced reducer 14, it can be quickly replaced with the old worm reducer 101. This allows the mill 10 to be restored to operation early. This makes it possible to shorten the downtime of the power plant 1, thereby suppressing a decrease in the availability rate of the power plant 1.

[0065] [Operation method of reducer 14] Next, a method of operating the reducer 14 will be described. First, the reducer 14 is subjected to an operation test at a factory before shipment to confirm its soundness before being shipped. The operation test may be performed without load or with load as necessary. When performing a test with load, a temporary flange may be installed on the output table 70 via a temporary thrust bearing, and a downward load may be applied to the temporary flange from the upper surface portion 61 of the reducer housing 60 with a bolt or the like to apply a simulated crushing load. In addition, the load against the rotation of the output table 70 may be applied by connecting a motor (generator) for power recovery that acts as a resistance to the output table 70 of the reducer 14, generating electricity to apply a load, or by connecting the input shaft 99 to the output table 70 via a speed increaser in a loop without slipping, and then applying a load by a power circulation method in which a torsional torque is applied to the loop.

[0066] After the reducer 14 is installed on the mill 10, a trial run is carried out to check its soundness before actual operation is carried out. During the trial run, the grinding table 12 is first rotated by hand to check that there are no obstacles impeding rotation. If an obstacle is found, it is removed. Next, the motor 15 is used to rotate the grinding table 12 under no load (no solid fuel is being supplied) to check that there are no problems with the temperature, noise, vibration, rotation speed, etc. of the mill 10 and each part of the reducer 14. Finally, an actual load operation is carried out (a state in which solid fuel is supplied and grinding is carried out) and the load on the mill 10 (amount of solid fuel supplied) is gradually increased to check that there are no problems with the temperature, noise, vibration, rotation speed, etc. of the mill 10 and each part of the reducer 14.

[0067] If the speed reducer 14 to be shipped is an initial product and no measurement data for each part exists, a strain gauge or the like may be attached to measure the stress generated in each part. Also, special instruments such as a vibration meter and a thermometer may be installed to obtain data.

[0068] In addition, by replacing the existing worm reducer 101 with the reducer 14 of this embodiment, the transmission efficiency of the reducer is improved and the loss of power is reduced compared to the existing worm reducer 101. That is, surplus power is generated. In order to utilize this surplus power, the reduction ratio of the spur gear (helical gear) constituting the reduction ratio change mechanism 90 may be changed and adjusted to a predetermined reduction ratio. For example, when the reduction ratio is lowered, the rotation speed of the grinding table 12 increases, and the surplus power can be used for grinding work to increase the rated processing capacity of the mill 10. On the other hand, when the reduction ratio is fixed, the power consumption of the motor 15 in the same operating state of the mill 10 decreases, so that it can be used to reduce the power consumption of the entire power generation plant 1. The target reduction ratio may be determined in advance at the planning stage, or may be determined after observing the operating conditions of the mill 10, such as the power consumption of the motor 15.

[0069] In addition, when the existing worm reducer 101 is replaced with the reducer 14 of this embodiment, the power consumption of the mill 10 (motor 15) in the same operating state of the mill 10 is reduced. This may cause problems in controlling the mill 10, such as an alarm for an insufficient power of the motor 15 (detecting a state in which solid fuel is not being supplied to the mill 10) or a malfunction in jam detection, which detects jamming of solid fuel between the grinding table 12 and the grinding roller 13 by a change in motor power (if jamming is not performed normally, the grinding roller 13 slips on the grinding table 12, causing vibration of the mill 10 and improper grinding). Therefore, after replacing the reducer, it is desirable to collect operating data of the mill 10 and appropriately review various operating control settings of the mill 10. In addition, by changing the operating settings so as to consume the improved power consumption of the mill 10, it is possible to obtain effects such as improving the grinding ability (fine powder particle size) of the mill 10 and enabling the grinding of solid fuels that are difficult to grind. For example, by increasing the rotation speed of the rotary classifier 16 to compensate for the increased power consumption, the power consumption of the motor 15 increases, but the fine powder size improves (becomes smaller), resulting in a decrease in the unburned content in the ash discharged from the boiler 200 and an improvement in the overall efficiency of the power plant 1. In addition, by increasing the crushing load by the pressing device 49 to compensate for the increased power consumption, the power consumption of the motor 15 increases, but it becomes possible to handle solid fuels that are difficult to crush.

[0070] According to this embodiment, the following advantageous effects are obtained. In conventional mills, a worm reducer 101 may be used as a reducer. In addition, in large mills, a twin worm reducer (see FIG. 8) in which two worm reducers 101 are combined in parallel may be used. In principle, such a worm reducer 101 has poor transmission efficiency because the tooth surfaces of the worm and the worm wheel are in sliding contact with each other when transmitting power. For this reason, most of the power generated by the motor 15 is consumed as heat, and the power that can be used for grinding is small. Therefore, the power consumption required to perform a certain grinding work increases, and the motor 15 also becomes larger. Furthermore, the oil cooler for cooling the lubricating oil supplied to the worm reducer 101 becomes larger and the amount of cooling water used increases, resulting in problems of high initial costs and running costs. On the other hand, in this embodiment, the reducer 14 using a highly durable planetary gear mechanism is used as the reducer of the mill 10. In the reduction section 80 of the reducer 14 using the planetary gear mechanism, a bevel gear is used for converting the direction of the rotation axis, and a planetary gear 82 is used for speed reduction, which enables more efficient power transmission than the worm reducer 101. Therefore, compared to the case where the worm reducer 101 is used, less motor power (power to rotate the input shaft 99) is required to obtain the same grinding power (shaft power transmitted from the output table 70 to the grinding table 12). Therefore, less power is required to perform the same grinding work, and the overall energy efficiency of the power generation plant 1 can be improved.

[0071] In addition, in the conventional worm reducer 101, there is a lot of slippage between the tooth surfaces, and in order to prevent adhesive wear and seizure, the tooth surfaces cannot be made of the same material, and an alloy steel material is used for the worm and a relatively soft copper alloy material is used for the worm wheel. However, the reducer 14 uses a planetary gear mechanism, which is a combination of a spur gear and an internal gear, and therefore, unlike the conventional worm reducer 101, there is little slippage between the tooth surfaces, and therefore hardened high-hardness steel can be used as the material for each gear. That is, each gear can be made into a hard gear. Therefore, the durability of each gear can be increased. Therefore, the life of the reducer 14 can be extended. In addition, the frequency of maintenance can be reduced, and therefore the running cost can be reduced. In addition, the oil cooler for cooling the lubricating oil supplied to the reducer 14 can be made smaller, and the amount of cooling water used can be reduced, so that both the initial cost and the running cost can be suppressed from this aspect as well.

[0072] Furthermore, in the reduction unit 80 using the planetary gear mechanism, the sun gear 81 and the planetary gears 82 have an automatic centering function with respect to the central axis C1. Therefore, unlike the worm reduction gear 101, tooth contact adjustment during assembly is almost unnecessary. Therefore, skilled techniques are not required during maintenance. Therefore, compared to the worm reduction gear 101, maintenance work can be made easier.

[0073] In recent years, there has been an increasing demand for high efficiency in thermal power generation facilities from the standpoint of the environment and costs. For this reason, it has been considered to improve the efficiency of existing thermal power generation facilities with low efficiency from the standpoint of the environment and costs. As one method for improving efficiency, it is considered to replace the existing worm reducer 101 (see FIG. 8) with a reducer (conventional planetary reducer 102 (see FIG. 9)) composed only of a planetary gear mechanism. However, generally, the worm reducer 101 is suspended from the mill 10, whereas the conventional planetary reducer is structured to be fixed to the foundation first. In this case, the path of the grinding load transmitted from the grinding table 12 is different between the worm reducer 101 and the conventional planetary reducer. Specifically, as shown in FIG. 8, in the suspended type worm reducer 101, the grinding load input from the grinding table to the worm reducer 101 is transmitted to the housing 11 of the mill 10 (see FIG. 4, etc.) via a plurality of reducer suspension bolts 101a. On the other hand, in the case of a conventional planetary reducer 102 that is fixed to a foundation, the crushing load is transmitted to the housing 11 of the mill 10 via the foundation of the mill 10. In this way, in a mill 10 equipped with a suspended type worm reducer 101, the foundation is not designed to transmit the crushing load, and therefore, in a mill 10 equipped with a suspended type worm reducer 101, replacing the worm reducer 101 with a conventional planetary reducer 102 requires significant modification of the foundation, resulting in problems of longer construction times and increased costs. On the other hand, in this embodiment, the reducer 14 is fixed so as to be suspended from the housing 11. This allows the fixing manner to be the same as that of a general worm reducer 101. This makes it possible to facilitate replacement work from the worm reducer 101 fixed so as to be suspended from the housing 11.

[0074] In addition, the position of the input shaft 99 into which the power is input is generally different between the worm reducer 101 and the conventional planetary reducer 102. Specifically, in the general worm reducer 101, the direction in which the central axis C6 of the input shaft 99 of the motor 15 extends does not intersect with the direction in which the central axis C1 of the grinding table 12 (output table 70) extends. In other words, in the general worm reducer 101, the central axis C6 of the input shaft 99 of the motor 15 and the central axis C1 of the grinding table 12 (output table 70) are in a twisted relationship. On the other hand, in the conventional planetary reducer 102, the direction in which the central axis C1 of the input shaft 99 of the motor 15 extends is perpendicular to the direction in which the central axis C7 of the grinding table 12 (output table 70) extends. Large-scale modification work is required to change the position or direction of the input shaft 99, so it was difficult to change from the worm reducer 101 to a conventional planetary reducer from this point of view as well. On the other hand, in this embodiment, the input shaft 99 of the motor 15 and the grinding table 12 are arranged so that the direction in which the central axis C5 of the input shaft 99 extends does not intersect with the direction in which the central axis C1 of the grinding table 12 extends. This allows the arrangement of the input shaft 99 and the grinding table 12 to be the same as that of a general worm reducer 101. This makes it possible to facilitate replacement work from the worm reducer 101.

[0075] In this embodiment, the reducer 14 has a reduction ratio changing mechanism 90 that can change the reduction ratio. That is, the reduction ratio of the reducer 14 (the reduction ratio from the rotation speed of the motor 15 to the rotation speed of the grinding table 12) can be varied by the reduction ratio changing mechanism 90. This allows the reduction ratio of the reducer 14 to be freely changed to a desired reduction ratio. Therefore, the rotation speed of the grinding table 12 can be set to a desired rotation speed. In this embodiment, the rotation speed of the grinding table 12 is set to the desired rotation speed by the reduction ratio changing mechanism 90 provided in the reducer 14. This eliminates the need to change the rotation speed of the motor 15. Therefore, there is no need to provide a device for changing the rotation speed of the motor 15 (for example, an inverter device or a pole change motor) or associated electrical equipment, and the structure can be simplified. In this manner, in this embodiment, the rotation speed of the rotary table 12 can be changed with a simple structure.

[0076] Specifically, in this embodiment, the reduction ratio change mechanism 90 has four spur gears that connect the sun gear 81 and the input shaft 99 of the motor 15. This allows the reduction ratio of the reducer 14 to be changed by changing the number of teeth of each spur gear (in other words, by adopting spur gears with different numbers of teeth). Therefore, the reduction ratio of the reducer 14 can be freely changed to a desired reduction ratio. Therefore, the rotation speed of the grinding table 12 can be set to a desired rotation speed. In addition, since the reduction ratio can be changed by using a plurality of gears (changing the reduction ratio), the rotation speed of the grinding table 12 can be set to the desired rotation speed with a simple structure.

[0077] The milling capacity of the mill 10 can be increased by increasing the rotation speed of the milling table 12. In this case, the power consumption required for milling also increases, but the surplus power generated by the improved transmission efficiency achieved by using a planetary gear mechanism can be used, making it unnecessary to make modifications to increase the capacity of the motor and electrical equipment. This makes it possible to crush hard-to-crush solid fuels (biomass fuels such as wood chips and low-quality charcoal, etc.), and with simple modifications it is possible to reduce carbon dioxide emissions and save on fuel costs.

[0078] In addition, in this embodiment, the milling capacity of the mill 10 can be reduced by reducing the rotation speed of the grinding table 12. This allows the mill 10 to be used in a lower load range (smaller supply amount of solid fuel) than before. In a conventional power plant, when there was a request to reduce the power generation load, some of the multiple mills 10 in operation were stopped, that is, the number of mills 10 in operation was changed to deal with the request. In this embodiment, the rotation speed of the grinding table 12 of the mill 10 is reduced, allowing the mill 10 to be operated in a lower load range, so that the load of the power plant 1 can be reduced without stopping the mills 10. Conventionally, as shown by the dashed line in FIG. 6, there is a time when the output change stops due to switching the number of mills 10 when the load changes. On the other hand, in this embodiment, since there is no need to switch the number of mills 10, there is no time when the output change stops due to switching the number of mills 10, as shown by the solid line in FIG. 6. For this reason, it is possible to improve the load change speed of the power plant 1 by the amount shown by the arrow A2. Therefore, it is possible to respond to the power demand fluctuation in the power grid, which has been borne by gas turbine combined cycle (GTCC) power plants using natural gas or the like in the past, by using thermal power plants using solid fuels such as coal. In other words, it is possible to reduce the total carbon dioxide emissions in the power grid by using GTCC or the like, which emits relatively small amounts of carbon dioxide per unit of power generation, as a baseload power source, and using thermal power plants using solid fuels, which emit relatively large amounts of carbon dioxide per unit of power generation, as a load adjustment power source. In addition, with some solid fuels such as PC (petrocoke), the grinding roller 13 may slip on the solid fuel loaded on the grinding table 12, causing vibrations in the mill 10. Even with fuels that are prone to slippage, the occurrence of slippage can be suppressed and stable grinding can be achieved by reducing the rotation speed of the grinding table 12. This allows for a diversification of fuels to be used, and makes it possible to reduce fuel costs.

[0079] The shaft of each spur gear requires a bearing, etc. Therefore, if the position of the shaft of each spur gear is made changeable, the structure becomes complicated and the modification work becomes extensive. On the other hand, in this embodiment, the reduction ratio is changed by four spur gears. That is, the reduction ratio is changed by an even number of spur gears. As a result, when the spur gear is changed to another spur gear with a different number of teeth in order to change the reduction ratio, the shaft position of each spur gear can be made the same as the position before the change by adjusting the diameter of the adjacent spur gear as shown in Figs. 5(a) and (b). Therefore, there is no need to provide a structure that can change the position of the shaft part. In this way, by changing the reduction ratio by an even number of spur gears, the structure of the reduction ratio change mechanism 90 can be simplified. Also, the work of changing the reduction ratio can be facilitated.

[0080] The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present disclosure. For example, in the above-described embodiment, the mill of the present disclosure is used, but the solid fuel may be biomass fuel or PC (Petroleum Coke) fuel generated during oil refining. In addition, each solid fuel may be mixed and used, or different fuels may be used in combination for the multiple mills 10.

[0081] Also, for example, in the above embodiment, a case where one reduction ratio change mechanism 90 is provided has been described, but the present disclosure is not limited thereto. For example, as shown in Fig. 7, two reduction ratio change mechanisms 111, 112 having different reduction ratios may be provided and the two may be switched by a clutch mechanism. Specifically, for example, a reducer 110 may include a first reduction ratio change mechanism 111 having a reduction ratio of 3:1 and a second reduction ratio change mechanism 112 having a reduction ratio of 4:1, and a clutch 113 connected to the motor-side bevel gear 97 may be used to change the power transmission path, thereby enabling speed changes while the mill 10 is operating or stopped.

[0082] Furthermore, in the multiple mills 10 installed in the power plant 1, the reduction ratio of the reducer 14 installed in each mill 10 may be different. In other words, the rotation speed of the grinding table 12 of each mill 10 may be different. For example, for the mill 10 used in the low load range of the power plant 1, the rotation speed of the grinding table 12 is set to be small. This expands the range of the supply amount of solid fuel that allows the mill 10 to operate stably to the smaller side, allowing the power plant 1 to operate at a lower load, thereby reducing the minimum load. In this case, the total grinding capacity of the mill 10 may be insufficient in the high load range of the power plant 1. In that case, the grinding capacity of the mill 10 can be increased by increasing the rotation speed of the grinding table 12 of the mill 10 used in the high load range. The increase in the power consumption of the mill 10 with an increased grinding capacity can be addressed by using a planetary reduction mechanism to improve the transmission efficiency and use the surplus power. In this way, the load changeable range of the power plant 1 can be expanded, improving operability.

[0083] Furthermore, when replacing with the reducer 14, if it is desired to reuse the existing motor, the rotation direction of the motor and the rotation direction of the mill 10 may not match. In such a case, the rotation directions may be matched by changing the number of spur gears that make up the reduction ratio change mechanism 90. This makes it possible to replace the reducer without replacing the motor 15.

[0084] In the above embodiment, the output spur gear 91, the input spur gear 92, the first spur gear 93, and the second spur gear 94 are arranged such that the central axes of the gears are aligned in a straight line, but the present disclosure is not limited to this. For example, depending on requirements such as the number of teeth, the direction of rotation, the reduction ratio, and the required length of the input shaft 99, the output spur gear 91, the input spur gear 92, the first spur gear 93, and the second spur gear 94 may be arranged such that the central axes of the gears meander. In other words, the output spur gear 91, the input spur gear 92, the first spur gear 93, and the second spur gear 94 may be arranged such that a line connecting the central axes of the gears forms a broken line when viewed from the direction in which the central axes extend.

[0085] The lubricating oil supplied to the reduction ratio change mechanism 90 may be supplied using an oil bath method in which each gear is submerged in the lubricating oil, or it may be supplied by forced oiling with each gear positioned above the lubricating oil level. However, if the spur gears that make up the reduction ratio change mechanism 90 are at the same height as the oil level, the oil level may be unnecessarily foamed, which may cause bubbles to escape or incompatibility such as air getting caught in the oil supply system. Therefore, the height of the oil level is set so that it is above the upper ends of each spur gear or below the lower ends of each spur gear.

[0086] In the above embodiment, the reduction ratio change mechanism 90 includes an even number of spur gears, but the present disclosure is not limited thereto. The reduction ratio change mechanism 90 may include an odd number of spur gears. However, if the reduction ratio change mechanism 90 includes an even number of spur gears, the reduction ratio can be changed without changing the shaft position of each spur gear by increasing or decreasing the diameter of adjacent gears as shown in FIG. 5(b). On the other hand, if there is only one spur gear between the output spur gear 91 and the input spur gear 92 and the number of spur gears is odd, as shown in FIG. 5(c) and (d), the shaft position of the intermediate spur gear 120 will be shifted (see arrow A1). Therefore, if the number of spur gears is odd in terms of the rotation direction, the intermediate spur gear 120 may be designed to have a changeable shaft position.

[0087] In the above embodiment, an example has been described in which a plurality of spur gears are used in the reduction ratio change mechanism 90, but the present disclosure is not limited thereto. For example, a profile shifted gear may be used instead of the spur gear. By using a profile shifted gear, the center distance can be adjusted.

[0088] In the above embodiment, an example has been described in which a plurality of spur gears are used in the reduction ratio change mechanism 90, but the present disclosure is not limited thereto. For example, a chain or a shaft may be used instead of the spur gears. When a shaft is used, a bevel gear, a screw gear, a crown gear, a hypoid gear, or the like may be provided on both ends of the shaft in order to change the transmission shaft direction.

[0089] Moreover, it is desirable to design the spur gear constituting the reduction ratio change mechanism 90 so that only the spur gear can be replaced with the reduction unit 80 using the planetary gear mechanism installed in the reducer housing 60. Specifically, for example, the reducer housing 60 may be provided with a hand hole, a maintenance hole, and an entrance for carrying in the gear to be replaced.

[0090] In the above embodiment, an example has been described in which the face widths (vertical lengths) of the multiple spur gears in the reduction ratio change mechanism 90 are the same, but the present disclosure is not limited to this. For example, the face widths of the spur gears constituting the reduction ratio change mechanism 90 may be changed, and the input spur gear 92 and the output spur gear 91 may be positioned differently in the height direction. Also, a structure may be used in which multiple gears are provided in the axial direction, and each gear is meshed with another gear.

[0091] In addition, the reducer side bevel gear 96 and the motor side bevel gear 97 are preferably spiral bevel gears that transmit smoothly and produce little noise, but they may be replaced with screw gears, crown gears, hypoid gears, etc.

[0092] In addition, it is preferable that the reducer side bevel gear 96 and the motor side bevel gear 97 are bevel gears of the same diameter, but depending on the space available, they may be bevel gears of different diameters to provide a reduction ratio.

[0093] In addition, since the reducer side bevel gear 96 and the motor side bevel gear 97 are disposed above the spur gears that constitute the reduction ratio change mechanism 90, a structure may be adopted in which sufficient lubricating oil is supplied by forced oil supply.

[0094] In addition, the lower part of the reduction gear housing 60 may be an oil pan that stores lubricating oil. The underside 62 of the reduction gear housing 60 serves as a support point when lifting or suspending the reduction gear housing 60 with a jack 104 or when pulling the reduction gear housing 60 with a dolly 103, and therefore may be strong enough to withstand its own weight.

[0095] Furthermore, the inner surface of the reducer housing 60 that does not come into contact with the housed components may be painted with a paint that is resistant to the lubricating oil used. The outer surface of the reducer housing 60 may also be painted with a paint that is resistant to oils and greases.

[0096] The gears and shafts used in the reducer 14 may be forged, heat treated, and then precisely machined. In particular, it is desirable to finish the tooth surfaces of the gears with high precision by grinding after cutting. It is also desirable to perform processing such as crowning on the planetary gears 82 to prevent damage caused by load concentration on one planetary gear 82 that may be disrupted by even a slight eccentricity or inclination.

[0097] Furthermore, since the planetary gears 82 transmit power using a plurality of planetary gears 82, it is preferable to use an odd number of planetary gears 82, which is advantageous for equal distribution of the transmitted power, and three planetary gears is most preferable in terms of equal distribution. With this configuration, for example, if a load is placed on one planetary gear 82 due to a slight processing error, the sun gear 81 moves away from the planetary gear 82 due to the automatic centering function and approaches the other two planetary gears 82, so that the same load can always be applied to all three planetary gears 82, and the load is not concentrated on one planetary gear 82, causing it to wear out, and the life of the reducer 14 can be extended.

[0098] Furthermore, in the multiple mills 10 installed in the power plant 1, the reduction ratio of the reducer 14 installed in each mill 10, i.e., the rotation speed of the grinding table 12, may be different. By configuring in this way, the total grinding capacity of all the mills 10 can be finely adjusted compared to a case in which the reduction ratios of the reducers 14 installed in all the mills 10 are the same. Therefore, it is possible to appropriately respond to the load fluctuation required of the power plant 1. Specifically, for example, the mill 10 that supplies solid fuel to the most frequently used burner 220 (generally, a burner arranged near the middle stage of the furnace of the boiler 200) may use the surplus power obtained by improving the transmission efficiency for energy saving (reducing the power consumption of the power plant 1 as a whole). On the other hand, the mill 10 that supplies fuel to the burner 220 (generally, a burner arranged in the upper and lower stages of the furnace of the boiler 200) that is used only when the power plant 1 is under high load may increase the rotation speed of the grinding table 12 and use the surplus power obtained by improving the transmission efficiency for expanding the fuel used in the power plant 1 and improving the ability to respond to load fluctuations. Furthermore, among the multiple mills 10 in the power plant 1, there may be a mill 10 that grinds only biomass fuel. With biomass fuel, particularly wood pellets, there may be cases where a solid fuel layer cannot be secured on the grinding table 12, which may cause vibration of the mill 10. In this case, the rotation speed of the grinding table 12 of the mill 10 that grinds the biomass fuel may be reduced to ensure a solid fuel layer on the grinding table 12. Furthermore, among the multiple mills 10 in the power generation plant 1, only the necessary mills 10 can be replaced with the reducer 14 described in this embodiment, and the reducers of the remaining mills 10 can be left unreplaced, thereby reducing modification costs.

[0099] The pulverizer, the power generation plant, and the method of operating the pulverizer described in the above-described embodiments can be understood, for example, as follows. A crusher according to one embodiment of the present disclosure includes a crushing table (12) that rotates with solid fuel supplied to its upper surface, crushing rollers (13) that press the solid fuel against the crushing table (12) to crush the solid fuel, a motor (15) that generates a driving force to rotate the crushing table (12), and a reducer (14) that transmits the driving force of the motor (15) to the crushing table (12), and the reducer (14) has a reduction ratio change mechanism (90) that can change the reduction ratio, and a reduction section (80) that uses a planetary gear mechanism.

[0100] In the above configuration, the reducer has a reduction ratio change mechanism that can change the reduction ratio. That is, the reduction ratio of the reducer can be changed by the reduction ratio change mechanism. This allows the reduction ratio of the reducer to be freely changed to a desired reduction ratio. Therefore, the rotation speed of the grinding table can be set to a desired rotation speed. In addition, in the above configuration, the rotation speed of the grinding table is set to the desired rotation speed by the reduction ratio change mechanism provided in the reducer. This makes it unnecessary to change the rotation speed of the motor. Therefore, it is not necessary to provide a device for changing the rotation speed of the motor and the associated electrical equipment, etc., and the structure can be simplified. In this manner, with the above configuration, the rotation speed of the rotary table can be changed with a simple structure.

[0101] In addition, in the crusher according to one aspect of the present disclosure, the motor (15) has an input shaft (99), The reducer (14) has a sun gear (81) that rotates coaxially with the grinding table (12), and the reduction ratio change mechanism (90) has a plurality of reduction ratio change gears (91, 92, 93, 94) that connect the sun gear (81) and the input shaft (99).

[0102] In the above configuration, the reduction ratio change mechanism has a plurality of reduction ratio change gears that connect the sun gear and the input shaft of the motor. This allows the reduction ratio of the reducer to be changed by changing the number of teeth of the reduction ratio change gears (in other words, by adopting reduction ratio change gears with different numbers of teeth). Therefore, the reduction ratio of the reducer can be freely changed to a desired reduction ratio. Therefore, the rotation speed of the grinding table can be set to a desired rotation speed. In addition, since the reduction ratio can be changed using multiple gears (reduction ratio changing gears), the rotation speed of the grinding table can be set to the desired rotation speed with a simple structure, compared to, for example, a case in which a device for changing the rotation speed of a motor is provided.

[0103] In addition, in the crusher according to one aspect of the present disclosure, an even number of the reduction ratio changing gears (91, 92, 93, 94) are provided.

[0104] In the above configuration, when the reduction ratio changing gear is replaced with another reduction ratio changing gear having a different number of teeth in order to change the reduction ratio, the shaft position of each reduction ratio changing gear can be made the same as the position before the change by adjusting the diameter of the adjacent gear. Therefore, the structure of the reduction ratio changing mechanism can be simplified. Also, the work of changing the reduction ratio can be made easier.

[0105] In addition, a crusher according to one embodiment of the present disclosure includes a housing (11) that is disposed above the reducer (14) and accommodates the crushing table (12), and the reducer (14) has a fixing portion (66) that fixes the reducer (14) so ​​as to be suspended from the housing (11).

[0106] Typically, the worm reducer is fixed so as to be suspended from the housing of the crusher. In the above configuration, the reducer has a fixing portion that fixes the reducer so that it is suspended from the housing. This allows the fixing manner to be the same as that of a general worm reducer. Therefore, for example, when replacing a worm reducer that is fixed so as to be suspended from a housing with a reducer having the above configuration, the replacement work can be facilitated.

[0107] In addition, in a crusher according to one embodiment of the present disclosure, the motor (15) has an input shaft (99), and the input shaft (99) and the crushing table (12) are arranged so that the extending direction of the central axis (C5) of the input shaft (99) and the extending direction of the central axis (C1) of the crushing table (12) do not intersect.

[0108] In a typical worm reducer, the input shaft of the motor and the grinding table are arranged so that the direction in which the central axis of the input shaft extends does not intersect with the direction in which the central axis of the grinding table extends. In the above configuration, the input shaft of the motor and the grinding table are arranged so that the direction in which the central axis of the input shaft extends does not intersect with the direction in which the central axis of the grinding table extends. This allows the arrangement of the input shaft and the grinding table to be the same as that of a general worm reducer. Therefore, when replacing a worm reducer with the above-mentioned configuration, the replacement work can be simplified.

[0109] A power generation plant according to one embodiment of the present disclosure includes a pulverizer (10) as described above, and a boiler (200) to which the solid fuel pulverized by the pulverizer (10) is supplied, and the pulverizers (10) are provided in plurality, and the reduction ratios of the reducers (14) of the plurality of pulverizers (10) are different.

[0110] In the above configuration, a plurality of pulverizers are provided, and the reduction ratio of the reducer of each pulverizer is different. This allows the total load of all the pulverizers to be finely adjusted compared to a case where the reduction ratio of the reducer of all the pulverizers is the same. Therefore, it is possible to appropriately respond to load changes required for the power plant.

[0111] Furthermore, a method of operating a crusher according to one embodiment of the present disclosure is a method of operating a crusher (10) that crushes solid fuel, the crusher (10) includes a crushing table (12) that rotates with the solid fuel supplied to its upper surface, a crushing roller (13) that presses the solid fuel against the crushing table (12) to crush the solid fuel, a motor (15) that generates a driving force to rotate the crushing table (12), and a reducer (14) that transmits the driving force of the motor (15) to the crushing table (12), the reducer (14) has a reduction ratio change mechanism (90) capable of changing the reduction ratio and a reduction section (80) that uses a planetary gear mechanism, and includes a step of changing the reduction ratio of the reducer (14) with the reduction ratio change mechanism (90). [Explanation of symbols]

[0112] 1: Power plant 10: Mill 11: Housing 12: Grinding table 13: Crushing roller 14:Reducer 15: Motor 16: Rotary classifier 16a: Blade 17:Fuel supply section 18: Classifier motor 19: Exit port 20:Coal feeding machine 21: Banka 22: Transport section 23: Coal feeder motor 24: Downspout 30: Blower section 30a: Hot gas flow path 30b: Cold gas passage 30c: Thermal gas damper 30d: Cold gas damper 31: Primary air ventilator 32: Forced ventilation fan 34:Heat exchanger 40: Status detection unit 41: Bottom part 42: Ceiling 45: Journal Head 47: Support arm 48: Support shaft 49: Pressing device 50: Control section 60: Reducer housing 61:Top part 62: Bottom part 63: Side wall 65: Partition wall part 66: Connection bolt 70: Output table 71: Table section 72: Table shaft 74: Thrust bearing 80: Reduction section 81: Sun gear 82: Planetary gear 83: Internal gear 84: Planetary frame 85:Connection shaft 90: Reduction ratio change mechanism 91: Output spur gear 91a: Output bearing 92: Input spur gear 92a: Input bearing 93: 1st spur gear 93a: First bearing 94: 2nd spur gear 94a: Second bearing 96: Reducer side bevel gear 97: Motor side bevel gear 99: Input shaft 99a: Motor input bearing 100: Solid fuel crushing device 100a: Primary air flow passage 100b: Pulverized fuel supply passage 101: Worm reducer 102: Planetary reducer 110: Reducer 111: First reduction ratio change mechanism 112: Second reduction ratio change mechanism 113: Clutch 120: Intermediate spur gear 200: Boiler 210: Furnace 220: Burner

Claims

1. A rotating grinding table on which solid fuel is supplied; a crushing roller for pressing the solid fuel onto the crushing table to crush the solid fuel; A motor that generates a driving force to rotate the grinding table; A reducer that transmits the driving force of the motor to the grinding table; A housing is provided above the reducer and accommodates the grinding table. The reducer includes: a reduction gear unit using a planetary gear mechanism and a reduction gear ratio change mechanism capable of changing the reduction gear ratio; A fixing portion that fixes the housing so as to be suspended therefrom; A crusher having a

2. The motor has an input shaft. The reducer has a sun gear that rotates coaxially with the grinding table, 2. The crusher according to claim 1, wherein the reduction ratio change mechanism includes a plurality of reduction ratio change gears connecting the sun gear and the input shaft.

3. 3. The crusher according to claim 2, wherein an even number of the reduction ratio changing gears are provided.

4. The motor has an input shaft.

2. The crusher according to claim 1, wherein the input shaft and the grinding table are arranged such that a direction in which a central axis of the input shaft extends does not intersect a direction in which a central axis of the grinding table extends.

5. A crusher according to any one of claims 1 to 4, a boiler to which the solid fuel pulverized by the pulverizer is supplied, A plurality of the crushers are provided, The power generation plant, wherein the plurality of pulverizers have reducers with different reduction ratios.

6. 1. A method of operating a pulverizer for pulverizing solid fuel, comprising the steps of: the crusher includes a crushing table having an upper surface onto which the solid fuel is supplied and which rotates, a crushing roller which presses the solid fuel against the crushing table to crush the solid fuel, a motor which generates a driving force for rotating the crushing table, a reducer which transmits the driving force of the motor to the crushing table, and a housing which is provided above the reducer and which accommodates the crushing table; The speed reducer includes a speed reducer unit using a speed reducer ratio change mechanism capable of changing a speed reducer ratio and a planetary gear mechanism, and a fixing unit that is fixed so as to be suspended from the housing, A method for operating a crusher comprising the step of changing the reduction ratio of the reducer by the reduction ratio change mechanism.

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