Crushing table and solid fuel crushing device, and crushing table repair method

Abstract

To inhibit wear of a support surface of a table part.SOLUTION: A crushing table 12 sandwiches an object to be crushed (a crushed object) with a crushing roller to crush the crushed object. The crushing table 12 includes: a table liner 60 which crushes the crushed object with an upper surface; a table part 70 having a support surface 73 which supports the table liner 60 from below; and a protection plate 80 which is provided between the table liner 60 and the table part 70 and covers the support surface 73. The protection plate 80 is formed of a material having a hardness lower than that of the support surface 73 of the table part 70.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a grinding table, a solid fuel grinding apparatus, and a method for repairing a grinding table. [Background technology]

[0002] Conventionally, solid fuels such as biomass fuels and coal are pulverized into fine powder within a predetermined particle size range in a pulverizer (mill) and then supplied to a combustion device. In the mill, the solid fuel fed onto the pulverizing table is pinched between the pulverizing table and pulverizing rollers to pulverize it. The pulverized solid fuel is then sorted into fine particles within a predetermined particle size range using a classifier. The fine particles are then transported to a boiler by a carrier gas (primary air) supplied from the periphery of the pulverizing table, where they are combusted in the combustion device. In a thermal power plant, steam is generated by heat exchange with the combustion gas produced by burning the pulverized fuel in the boiler. This steam drives a steam turbine, which in turn drives a generator connected to the steam turbine, thereby generating electricity.

[0003] As a grinding table provided in a mill, a known one is one in which a table liner is disposed in an annular shape on the table portion, and solid fuel is sandwiched between the table liner and grinding rollers to be ground (for example, Patent Document 1). The grinding table described in Patent Document 1 has a ring-shaped groove formed in the table portion, and table segments are provided within this groove. Also, in the grinding table described in Patent Document 1, shims, which serve as height adjustment means, are laid out on the bottom surface of the groove, and the table segments are provided on the shims. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-183333 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, the table portion of the grinding table is made of a material that is lower in hardness and higher in toughness than the table liner that grinds the solid fuel, and therefore the table portion is more susceptible to wear than the table liner. As the mill operates, wear may occur between the table portion and the table liner due to abrasion caused by solid fuel that has gotten in between the table portion and the table liner, or due to fretting, etc. In this case, as described above, the table portion is more susceptible to wear than the table liner, and therefore deformation due to wear is likely to occur on the table side. As wear progresses on the table portion, unevenness may occur on the surface that supports the table liner. If unevenness occurs on the table portion, the contact surface between the table portion and the table liner may become loose, or the table liner may become loose. In addition, the crushing load applied by the crushing roller is transmitted in the order of the table liner and the table portion via the solid fuel being crushed. Therefore, if unevenness exists on the table portion, a localized excessive load may act on the table liner, potentially damaging the table liner.

[0006] The grinding table described in Patent Document 1 has shims provided below the table segments. However, since these shims are height adjustment means, they do not take into consideration wear and tear on the table portion.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a grinding table, a solid fuel grinding device, and a grinding table repair method that can suppress wear on the support surface of the table portion. [Means for solving the problem]

[0008] In order to solve the above problems, the grinding table, solid fuel grinding device, and grinding table repair method of the present disclosure employ the following means. A grinding table according to one aspect of the present disclosure is a grinding table that grinds an object to be ground by sandwiching the object between the grinding roller and the table liner, and includes a table liner that grinds the object to be ground on its upper surface, a table portion having a support surface that supports the table liner from below, and a protective plate that is provided between the table liner and the table portion and covers the support surface, and the protective plate is formed of a material that is less hard than the support surface of the table portion.

[0009] Furthermore, a method for repairing a grinding table according to one aspect of the present disclosure is a method for repairing a grinding table that grinds an object to be ground by sandwiching the object between the grinding rollers, wherein the grinding table has a table liner that grinds the object to be ground on its upper surface and a table portion having a support surface that supports the table liner from below, and the method includes a removal process for removing the table liner from the table portion, a repair process for repairing the support surface after the removal process so that the support surface is flat, and an installation process for installing a protective plate formed of a material having a lower hardness than the support surface of the table portion so as to cover the support surface after the repair process. [Effects of the Invention]

[0010] According to the present disclosure, wear on the support surface of the table portion can be suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing a solid fuel pulverizer and a boiler according to an embodiment of the present disclosure. FIG. [Figure 2] FIG. 2 is a diagram showing a vertical cross section of a main part (portion A in FIG. 1) of a rotary table according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a vertical cross-sectional view of a main part of a grinding table according to an embodiment of the present disclosure, showing the state before repair. [Figure 4] FIG. 10 is a diagram illustrating a state in which machining is being performed on a grinding table according to an embodiment of the present disclosure. [Figure 5]FIG. 10 is a diagram illustrating a state in which machining is being performed on a grinding table according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a diagram showing a vertical cross section of a main part of a grinding table according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a cross-sectional view taken along the arrow BB in FIG. 6. [Figure 8] FIG. 8 is a diagram showing a modification of FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a grinding table, a solid fuel grinding device, and a grinding table repair method according to the present disclosure will be described below with reference to the drawings.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will now be described with reference to the accompanying drawings. A power plant 1 according to this embodiment includes a solid fuel pulverizer 100 and a boiler 200. The power plant 1 includes a solid fuel pulverizer 100 and a boiler 200. The solid fuel pulverizer 100 includes a fuel cell 100a. In the following explanation, "upper" refers to the vertically upward direction, and "upper" in terms such as upper part and upper surface refers to the vertically upward part. Similarly, "lower" refers to the vertically downward 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, such as biomass fuel or coal, to generate pulverized fuel and supply it to a burner (combustion device) 220 of a boiler 200, for example. 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 comprises a mill (pulverizing section) 10, a bunker (storage section) 21, a coal feeder (fuel supplying machine) 25, a blower (carrier gas supplying section) 30, a status detection section 40, and a control section 50.

[0016] The mill 10, which pulverizes solid fuel such as coal or biomass fuel to be supplied to the boiler 200 into finely divided fuel, which is a finely divided solid fuel, may be of a type that pulverizes only coal, or 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 fuel refers to 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 is not limited to the ones listed here.Biomass fuels are carbon neutral, meaning they do not emit carbon dioxide, a greenhouse gas, because they absorb carbon dioxide during the biomass growth process, and various uses for them are being considered.

[0017] The mill 10 comprises a housing 11, a grinding table 12, grinding rollers 13, a reducer (drive transmission unit) 14, a mill motor (drive unit) 15 connected to the reducer 14 and driving the grinding table 12 to rotate, a rotary classifier (classification unit) 16, a coal supply pipe (fuel supply unit) 17, and a classifier motor 18 that drives the rotary classifier 16 to rotate. The housing 11 is formed in a cylindrical shape extending in the vertical direction, and is a case that accommodates the crushing table 12, the crushing rollers 13, the rotary classifier 16, and the coal feed pipe 17. A coal feed pipe 17 is attached to the center of the ceiling portion 42 of the housing 11. This coal feed pipe 17 supplies solid fuel guided from the bunker 21 via the coal feeder 25 into the housing 11. It is arranged vertically at the center of the housing 11 and has its lower end extending into the interior of the housing 11.

[0018] A reducer 14 is installed near the bottom surface 41 of the housing 11, and a mill motor 15 connected to the reducer 14 transmits a driving force to rotate the grinding table 12, which is rotatably arranged. The grinding table 12 is a circular member in a plan view, and is arranged so that the lower end of the coal feed pipe 17 faces it. The upper surface of the grinding table 12 may, for example, have an inclined shape that is low in the center and rises toward the outside, with the outer periphery bending upward. The coal feed pipe 17 supplies solid fuel (in this embodiment, for example, coal or biomass fuel) from above toward the grinding table 12 below, and the grinding table 12 sandwiches the supplied solid fuel between itself and the grinding rollers 13 and grinds it.

[0019] When solid fuel is fed from the coal feed pipe 17 toward the center of the pulverizing table 12, the centrifugal force generated by the rotation of the pulverizing table 12 guides the solid fuel toward the outer periphery of the pulverizing table 12, where it is pinched and pulverized between the pulverizing table 12 and the pulverizing rollers 13. The pulverized solid fuel is blown upward by the carrier gas (hereinafter referred to as primary air) guided from the carrier gas flow path (hereinafter referred to as primary air flow path) 110, 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 primary air flowing in from the primary air flow path 110 flows out into the space above the grinding table 12 within the housing 11. A swirl 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 swirl blade becomes an airflow having a swirling velocity component, and transports the solid fuel pulverized on the grinding table 12 to the rotary classifier 16 located above in the housing 11. Of 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 and are returned to the grinding table 12, where they are pulverized again between the grinding table 12 and the grinding rollers 13.

[0020] The crushing roller 13 is a rotating body that crushes the solid fuel supplied onto the crushing table 12 from the coal supply pipe 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 of the three crushing rollers 13 that come into contact with the upper surface of the crushing table 12 (pressing portions) are equidistant from the rotational axis of the crushing table 12.

[0021] The crushing roller 13 can be swung and displaced up and down by the journal head 45, and is supported so as to be able to move towards and away from the upper surface of the crushing table 12. When the crushing table 12 rotates, the crushing roller 13 receives a rotational force from the crushing table 12 and rotates with it, 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. When solid fuel is supplied from the coal supply pipe 17, the solid fuel is pressed between the crushing roller 13 and the crushing table 12 and crushed. This pressing force is called the crushing load.

[0022] The 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 horizontally aligned, allowing the crushing roller 13 to swing and displace up and down about the support shaft 48. A pressing device (crushing load applying unit) 46 is provided at the upper end portion vertically above the support arm 47. The pressing device 46 is fixed to the housing 11 and applies a crushing load to the crushing roller 13 via the support arm 47 and the like so as to press the crushing roller 13 against the crushing table 12. The crushing load is applied, for example, by a hydraulic cylinder (not shown) operated by the pressure of hydraulic oil supplied from a hydraulic device (not shown) installed outside the mill 10. The crushing load may also be applied by the repulsive force of a spring (not shown).

[0023] The reducer 14 is connected to a mill motor 15, and transmits the driving force of the mill motor 15 to the grinding table 12, causing the grinding table 12 to rotate around its central axis.

[0024] The rotary classifier (classification unit) 16 is provided at the top of the housing 11 and has a hollow, inverted cone-like outer shape. The rotary classifier 16 is provided with a plurality of blades 16a extending in the vertical direction around 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 solid fuel pulverized by the pulverizing table 12 and pulverizing rollers 13 (hereinafter, the pulverized solid fuel will be referred to as "pulverized fuel") into particles larger than a predetermined particle size (for example, 70 to 100 μm for coal) (hereinafter, pulverized fuel exceeding the predetermined particle size will be referred to as "coarse pulverized fuel") and particles smaller than the predetermined particle size (hereinafter, pulverized fuel smaller than the predetermined particle size will be referred to as "fine pulverized fuel"). The rotary classifier 16 is given a rotational driving force by a classifier motor 18 controlled by the control unit 50, and rotates around a coal feed pipe 17, centered on a cylindrical axis (not shown) extending in the vertical direction of the housing 11. The classifying section may be a fixed classifier having a fixed hollow inverted cone-shaped casing and a plurality of fixed swirl 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 led 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 together with the primary air from the outlet port 19 into the pulverized fuel supply flow path (pulverized fuel supply pipe) 120 and supplied to the burner 220 of the boiler 200.

[0026] The coal feed pipe 17 is attached so that its lower end extends vertically into the interior of the housing 11, penetrating the ceiling 42 of the housing 11, and supplies solid fuel fed from the top of the coal feed pipe 17 to the center of the grinding table 12. A coal feeder 25 is connected to the upper end of the coal feed pipe 17, and solid fuel is supplied thereto.

[0027] The coal feeder 25 is connected to the bunker 21 by a downspout 22, which is a pipe extending vertically from the lower end of the bunker 21. A valve (coal gate, not shown) for switching the discharge state of the solid fuel from the bunker 21 may be provided midway through the downspout 22. The coal feeder 25 includes a conveying unit 26 and a coal feeder motor 27. The conveying unit 26 is, for example, a belt conveyor, and conveys the solid fuel discharged from the lower end of the downspout 22 to the upper part of the coal feed pipe 17 by the driving force of the coal feeder motor 27, and then deposits it inside. The amount of solid fuel supplied to the mill 10 is controlled by a signal from the control unit 50, for example, by adjusting the movement speed of the belt conveyor of the conveying unit 26.

[0028] Normally, primary air is supplied to the inside of the mill 10 to transport pulverized fuel to the burner 220, and the pressure is higher than that of the coal feeder 25 and the bunker 21. Inside the downspout section 22 that connects the bunker 21 and the coal feeder 25, fuel is layered. This solid fuel layer ensures a sealing property (material seal) that prevents the primary air and pulverized fuel from flowing back from the mill 10 toward the bunker 21.

[0029] The blower 30 is a device that blows primary air into the housing 11 to dry the pulverized fuel and transport it to the rotary classifier 16 . 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 in order to appropriately adjust the flow rate and temperature of the primary air blown into the inside of the housing 11.

[0030] In this embodiment, the hot gas flow path 30a supplies a portion of the air sent out from the primary air fan 31 as hot gas that has been heated by passing through an air preheater (heat exchanger) 34. A hot gas damper 30c is provided in 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.

[0031] 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 in 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. The hot gas flow path 30a may be provided with a shutoff damper (not shown) that shuts off the flow of hot gas. The shutoff damper may be opened and closed under the control of the control unit 50 or manually.

[0032] 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. Furthermore, the oxygen concentration in the primary air blown from the primary air passage 110 into the housing 11 may be adjusted by, for example, introducing a portion of the combustion gas discharged from the boiler 200 by a gas recirculation fan (not shown) into the hot gas supplied from the hot gas passage 30a and mixing the same. By adjusting the oxygen concentration in the primary air, for example, when a highly ignitable (easily ignitable) solid fuel is used, it is possible to prevent the solid fuel from igniting on the path from the mill 10 to the burner 220.

[0033] In this embodiment, data measured or detected by the state detection unit 40 of the mill 10 is transmitted 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 differential pressure between the pressure at the portion where primary air flows from the primary air flow path 110 into the inside of the housing 11 and the pressure at the outlet port 19 where the primary air and pulverized fuel are discharged from the inside of the housing 11 to the pulverized fuel supply pipe 120. 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 according to the differential pressure of the mill 10, the amount and particle size range of the pulverized fuel discharged from the outlet port 19 can be adjusted, so that the particle size of the pulverized fuel can be maintained within a range that does not affect the combustibility of the solid fuel in the burner 220, and 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. Furthermore, the state detection unit 40 of this embodiment is, for example, a temperature measurement means that detects the temperature of the primary air supplied to the inside of the housing 11 (mill inlet primary air temperature) and the temperature of the mixed gas of primary air and pulverized fuel at the outlet port 19 (mill outlet primary air temperature), and controls the blower unit 30 so that the respective upper limit temperatures do not exceed them. Each upper limit temperature is determined taking into consideration the possibility of ignition depending on the properties of the solid fuel. Note that, since the primary air is cooled inside the housing 11 by drying and transporting the pulverized fuel, the primary air temperature at the mill inlet is, for example, from room temperature to approximately 300°C, and the primary air temperature at the mill outlet is, for example, from room temperature to approximately 90°C.

[0034] The control unit 50 is a device that controls each part of the solid fuel pulverizer 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 to adjust the classification performance, and can stably supply to the burner 220 an amount of pulverized fuel corresponding to the amount of solid fuel supplied to the mill 10 while maintaining the particle size of the pulverized fuel within a range that does not affect the combustibility of the solid fuel in the burner 220. Furthermore, the control unit 50 can adjust the amount of solid fuel supplied to the mill 10 (amount of coal supply) by transmitting a drive command to the coal supply motor 27, for example. Furthermore, the control unit 50 can adjust the flow rate and temperature of the primary air by controlling the opening rates of the hot gas damper 30c and the cold gas damper 30d by transmitting an opening rate instruction to the blower unit 30. Specifically, the control unit 50 controls the opening rates 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 (mill outlet primary air temperature) become predetermined values ​​set corresponding to the coal feed rate for each type of solid fuel. Note that the temperature of the primary air may also be controlled by controlling the temperature at the mill inlet (mill inlet primary air temperature).

[0035] The control unit 50 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), The software is composed of a memory (ROM), a read-only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in the storage medium in the form of a program, for example. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories. Furthermore, HDDs may be replaced with solid-state disks (SSDs), etc.

[0036] Next, a description will be given of the boiler 200 that generates steam by burning the pulverized fuel supplied from the solid fuel pulverizer 100. The boiler 200 includes a furnace 210 and a burner 220.

[0037] The burner 220 is a device that burns pulverized fuel to form a flame using a mixture of pulverized fuel and primary air supplied from the pulverized fuel supply pipe 120 and secondary air supplied by heating air (outside air) sent out from a forced draft fan (FDF) 32 with an air preheater 34. The pulverized fuel is burned in the furnace 210, and the high-temperature combustion gas passes through heat exchangers (not shown) such as an evaporator, a superheater, and a coal economizer before being discharged to the outside of the boiler 200.

[0038] The combustion gas discharged from the boiler 200 undergoes predetermined treatment in environmental equipment (such as a denitration device, dust collector, and desulfurization device, not shown), and then undergoes heat exchange with primary air and secondary air in an air preheater 34. 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 heated by the combustion gas in the air preheater 34 and delivered from the primary air fan 31 is supplied to the above-mentioned hot gas flow path 30a. The water supplied to each heat exchanger of the boiler 200 is heated in a coal economizer (not shown), and then further heated in an evaporator (not shown) and a superheater (not shown) to generate high-temperature, high-pressure superheated steam, which is then sent to the steam turbine (not shown), which is the power generation section, to rotate and drive the steam turbine, which then rotates and drives a generator (not shown) connected to the steam turbine to generate electricity, thereby constituting the power generation plant 1.

[0039] [Grinding Table] Next, the details of the rotary table 12 will be explained with reference to Fig. 2. Fig. 2 is an enlarged view of the main part (portion A) of Fig. 1.

[0040] As shown in FIG. 2, the grinding table 12 includes a table liner 60 that grinds the solid fuel on its upper surface, a table portion 70 having a support surface 73 that supports the table liner 60 from below, a protective plate 80 that is provided between the table liner 60 and the table portion 70 and covers the support surface 73, and a key 90 that restricts the relative movement between the table liner 60 and the table portion 70.

[0041] The table liner 60 is a member having a circular shape in a plan view. The solid fuel is supplied to an upper surface 61 of the table liner 60. The upper surface 61 of the table liner 60 is concave downward. The crushing table 12 crushes the solid fuel supplied to the upper surface 61 of the table liner 60 by sandwiching it between the crushing roller 13 (see FIG. 1 ).

[0042] The table liner 60 is placed on the protective plate 80. In other words, substantially the entire lower surface 62 of the table liner 60 is in surface contact with the upper surface of the protective plate 80. A key groove 63 is formed on the outer periphery of the lower surface 62 of the table liner 60 (see Figures 2 and 7). The key groove 63 is recessed upward from the lower surface 62. A key 90 is fitted into the key groove 63.

[0043] The table liner 60 is formed of a high-hardness material to suppress wear, since the solid fuel is crushed on the upper surface 61. In detail, the table liner 60 is formed of a material harder than the table portion 70 and the protective plate 80. The table liner 60 may be formed of, for example, high-chromium steel, cast iron, cast steel, etc.

[0044] The table portion 70 is connected to the reducer 14 (see FIG. 1). The table portion 70 rotates by the driving force of the mill motor 15 (see FIG. 1) transmitted via the reducer 14. The table portion 70 rotates about a central axis extending vertically.

[0045] The table portion 70 integrally includes a base portion 71 whose lower portion is connected to the reducer 14 and a wall portion 72 erected on the outer periphery of the base portion 71 . The upper surface of the base 71 serves as a support surface 73 that supports the table liner 60 from below. A recess 74 that is recessed downward is formed in the support surface 73. The recess 74 is formed over the entire circumferential area of ​​the support surface 73. The depth of the recess 74 is the same length as the thickness of the protective plate 80.

[0046] A key groove 75 is formed on the outer periphery of the support surface 73 of the table portion 70 (see FIGS. 2 and 7). The key groove 75 is recessed downward from the support surface 73 (more specifically, from the bottom surface 74a of the recess 74). A key 90 is fitted into the key groove 75.

[0047] The table portion 70 is formed of a material that is less hard than the table liner 60. The table portion 70 is also formed of a material that is harder than the protective plate 80. The table portion 70 may be formed of, for example, a carbon steel casting.

[0048] The protective plate 80 is a plate-like member. The protective plate 80 is an annular member. The protective plate 80 may be divided into a plurality of members to form an annular shape. The protective plate 80 is disposed so as to be sandwiched between the table liner 60 and the table portion 70. The outer periphery and / or inner periphery of the protective plate 80 is welded and fixed to the table portion 70. The protective plate 80 is provided inside a recess 74 formed in the support surface 73 of the table portion 70. The protective plate 80 covers at least a portion of the support surface 73 of the table portion 70 (an area corresponding to substantially the entire lower surface 62 of the table liner 60) from above. More specifically, the protective plate 80 covers the bottom surface 74a of the recess 74 from above. The lower surface of the protective plate 80 is in surface contact with the support surface 73 of the table portion 70. The height position of the upper surface of the protective plate 80 is the same as the height position of the area of ​​the support surface 73 where the recess 74 is not formed. In other words, the upper surface of the protective plate 80 is arranged so as to be flush with the area of ​​the support surface 73 where the recess 74 is not formed. The upper surface of the protective plate 80 is in surface contact with the entire lower surface of the table liner 60. The upper and lower surfaces of the protective plate 80 are smooth and flat.

[0049] A key hole 81 through which a key 90 is inserted is formed in the protective plate 80. The key hole 81 is arranged so as to overlap, in plan view, with the key groove 63 formed in the table liner 60 and the key groove 75 formed in the table portion 70.

[0050] The thickness of the protective plate 80 is the same as the depth of the recess 74 formed in the support surface 73. The thickness of the protective plate 80 is, for example, 10 mm or more and 15 mm or less. Note that the thickness of the protective plate 80 is not limited to the above range. For example, the thickness of the protective plate 80 may be greater than 15 mm.

[0051] The protective plate 80 is made of a material having a compressive strength sufficient to withstand the crushing load applied by the crushing roller 13. The protective plate 80 is also made of a material having a lower tensile strength than the table portion 70. Moreover, the protective plate 80 is formed of a material that is lower in hardness than the table liner 60 and the table portion 70 (particularly the support surface 73). The protective plate 80 may be formed of, for example, mild steel such as SS400, or copper.

[0052] The upper part of the key 90 fits into a key groove 63 formed in the table liner 60. The lower part of the key 90 fits into a key groove 75 formed in the table part 70. The key 90 also passes through a key hole 81 formed in the protective plate 80.

[0053] The rotary table 12 including the protective plate 80 according to this embodiment is configured as described above. The protective plate 80 may be installed when manufacturing a new rotary table 12. Also, the protective plate 80 may be installed when repairing an existing rotary table 12 (see FIG. 3) that does not have a protective plate 80.

[0054] [Repair method] Next, a repair method for the rotary table 12 according to this embodiment will be described with reference to Figures 3 to 8. Below, a repair method for newly installing a protective plate 80 when repairing a rotary table 12 that does not have a protective plate 80 will be described.

[0055] In the mill 10, the solid fuel is caught between the crushing roller 13 and the table liner 60 and is finely crushed by the crushing load applied by the crushing roller 13. Therefore, after a certain amount of operation, the surfaces of the crushing roller 13 and the table liner 60 wear. The crushing roller 13 and the table liner 60 are made of a hard material to ensure wear resistance, but wear cannot be prevented with use, so they gradually wear out. When the amount of wear on the crushing roller 13 and the table liner 60 reaches an allowable value, it becomes difficult to operate stably thereafter, and therefore the crushing roller 13 and the table liner 60 must be repaired or replaced.

[0056] Furthermore, although the support surface 73 of the table portion 70 does not directly face the space inside the housing 11, wear may occur at the contact area between the table portion 70 and the table liner 60 due to abrasion caused by solid fuel that gets between the table portion 70 and the table liner 60 as the mill 10 operates, or due to fretting, etc. Generally, the table portion 70 is more susceptible to wear because it is often made of a material that is less wear-resistant than the table liner 60, which is the grinding portion. When wear occurs at the contact area between the table portion 70 and the table liner 60, the table portion 70 will be deformed. Specifically, as shown in FIG. 3, unevenness will occur on the support surface 73 of the table portion 70.

[0057] In this way, wear occurs on the upper surface of the table liner 60 and the support surface of the table portion 70 of the grinding table 12. Since wear hinders stable operation of the mill 10, the grinding table 12 needs to be repaired at regular intervals.

[0058] When repairing the rotary table 12, first, the table liner 60 is removed from the table portion 70 (removal process).

[0059] Next, the deterioration state of the support surface 73 of the table portion 70 is checked. That is, it is checked whether or not there are any irregularities or the like on the support surface 73. As shown in FIG. 3, if it is determined that the support surface 73 has deteriorated and has irregularities, the support surface 73 is processed to remove the irregularities (repair process). Specifically, recesses 74 are formed on the support surface 73 so that the irregularities disappear and the support surface 73 becomes flat (horizontal). That is, the support surface 73 is processed so that it is perpendicular to the central axis C of the table portion 70.

[0060] The processing method for forming the recess 74 is not limited to a specific method. For example, as shown in Fig. 4, the recess 74 may be formed by a cutting device 130 installed in the mill 10. The cutting device 130 has a turning tool 131, a horizontal rail 132 that moves the turning tool 131 in the horizontal direction, and a vertical rail 133 that moves the turning tool 131 in the up and down direction. When forming the recesses 74 with the cutting device 130, the table 70 is rotated, and the turning tool 131 is moved in the direction of the central axis of the table 70 (up and down), to cut into the support surface 73. With the turning tool 131 cut into the support surface 73, the turning tool 131 may be moved in the radial direction, and the recesses 74 may be formed by turning the support surface 73 as if using a vertical lathe.

[0061] 5, the recess 74 may be formed by a milling machine 140 installed on the table 70 of the mill 10. The milling machine 140 includes a cutter 141, an arm 142 that rotates the cutter 141 about a central axis C, and a moving unit 143 that moves the cutter 141 in the up and down direction. When the recess 74 is formed by the milling machine 140, the cutter 141 is moved in the circumferential direction around the central axis C to perform milling.

[0062] Furthermore, the more the table portion 70 is cut, the thinner the base portion 71 of the table portion 70 becomes, and the lower the strength becomes. For this reason, it is preferable that the amount of cutting (i.e., the depth of the recess 74 to be formed) be the minimum amount that can remove the irregularities formed on the support surface 73 of the table portion 70. Therefore, before processing, the maximum amount of processing of the support surface 73 of the table portion 70 in terms of strength is determined, and the recess 74 is formed so that the thickness T (see FIG. 2) necessary for the strength of the base 71 of the table portion 70 remains. If unevenness remains on the support surface 73 of the table portion 70 even after machining to the limit, the table portion 70 itself may be replaced, or the thickness may be restored by overlay welding. If overlay welding is performed, it is preferable to perform an appropriate heat treatment to eliminate the welding heat effect (residual stress). When turning the support surface 73, the table portion 70 may be rotated by the driving force of the mill motor 15, or the table portion 70 may be rotated using a temporary motor.

[0063] After the recesses 74 are formed on the support surface 73, the depth of the recesses 74 is measured. The depth of the recess 74 is preferably measured from a reference surface of the table portion 70. The reference surface is preferably the bottom surface 70a of the table portion 70, which is less susceptible to wear and deformation during operation, or the installation surface 70b of a dam ring (not shown) installed on the outermost periphery of the table portion 70.

[0064] Next, a protection plate 80 having a thickness corresponding to the measured depth of the recess 74 is manufactured (protection plate manufacturing step). Specifically, a protection plate 80 having the same thickness as the depth of the recess 74 is manufactured.

[0065] Next, the protective plate 80 is placed in the recess 74 (placement process). At this time, a measurement is made to see if the height position of the upper surface of the protective plate 80 is the same as the height position of the area of ​​the support surface 73 where the recess 74 is not formed. In other words, a measurement is made to see if the upper surface of the protective plate 80 and the area of ​​the support surface 73 where the recess 74 is not formed are flush with each other. If they are not flush with each other, the table portion 70 and / or the protective plate 80 are processed again.

[0066] Once it has been confirmed that the upper surface of the protective plate 80 is flush with the area of ​​the support surface 73 where the recess 74 is not formed, the protective plate 80 is welded and fixed to the table portion 70. Next, a key 90 is inserted into the key hole 81 and fitted into the key groove 75 of the table portion 70. Next, a new table liner 60 is placed on the upper surface of the protective plate 80. At this time, the table liner 60 is placed so that the key groove 63 fits into the key 90.

[0067] Once the new table liner 60 is installed, the grinding table 12 repair work is complete.

[0068] The above repair method is just one example, and the method for repairing the grinding table 12 is not limited to the above method. For example, it may be changed as appropriate depending on the conditions of the site or process. Specifically, for example, in the case of a short delivery time, multiple protective plates 80 of different thicknesses may be prepared in advance, and after the recess 74 is formed, a protective plate 80 of an appropriate thickness may be selected and installed in the recess 74. Furthermore, when forming the recess 74, the amount of processing (i.e., the depth of the recess 74) may be determined according to the thickness of the protective plate 80 that has been manufactured in advance.

[0069] Furthermore, the protective plate 80 is more susceptible to wear and tear due to aging than the table portion 70. Therefore, if the protective plate 80 is found to be deteriorating or worn out during subsequent repairs of the grinding table 12, it may be replaced along with the table liner 60. By replacing the protective plate 80 in this way, the protective plate 80's wear-suppressing function for the table portion 70 can be maintained, thereby suppressing wear and tear on the table portion 70. However, since it is impossible to completely eliminate the deterioration of the table liner 60 and the table portion 70 over time, the table portion 70 may be re-machined after extended use. That is, the recesses 74 on the support surface 73 may be re-machined. When re-machining the recesses 74, it is necessary to avoid exceeding the maximum machining amount of the support surface 73 of the table portion 70 due to its strength. Therefore, minimizing the machining amount of the table portion 70 each time increases the number of times it can be machined, thereby increasing the number of times the table portion 70 can be used before it needs to be replaced.

[0070] Furthermore, the keyway 75 of the table portion 70 becomes shallower due to the formation of the recess 74 in the support surface 73 of the table portion 70. Therefore, after the recess 74 is formed in the support surface 73 of the table portion 70, it is necessary to re-machine the keyway 75 so that it becomes deeper (see the arrow in FIG. 6). Furthermore, the thickness of the key 90 must be increased by the amount corresponding to the provision of the protective plate 80. Therefore, when repairing, a key 90 that is thicker than the key before repair must also be prepared. As shown in FIG. 7, the moment that tends to tip the key 90 due to the rotational force of the table portion 70 (see the arrow in FIG. 7) increases as the thickness of the key 90 increases. The component stress due to the tipping moment of the key 90 also increases. For this reason, as shown in FIG. 8, the width of the key 90 may be increased as needed to ensure the strength of the key 90, keyhole 81, and keyways 63 and 75. Furthermore, the depth of the keyways 63 and 75 may be increased to ensure strength. The keyways 63 and 75 may be machined deeper than the pre-repair keyways, or new keyways may be formed in different positions. When forming new keyways, a key or the like may be inserted into the unused pre-repair keyway and filled in.

[0071] According to this embodiment, the following advantageous effects are achieved. In this embodiment, the protective plate 80, which is made of a material that is lower in hardness than the support surface 73 of the table portion 70, covers the support surface 73. This means that the protective plate 80 actively absorbs wear caused by friction between the protective plate 80 and the table portion 70, wear caused by foreign matter that has entered between the protective plate 80 and the table portion 70, and the like. In other words, the protective plate 80 wears out before the support surface 73 of the table portion 70. This makes it possible to suppress wear on the support surface 73 of the table portion 70.

[0072] Furthermore, wear on the support surface 73 of the table portion 70 can be suppressed, making it difficult for unevenness to form on the support surface 73. This makes it difficult for localized loads to act on the table liner 60 supported by the support surface 73. Therefore, damage to the table liner 60 can be suppressed.

[0073] Furthermore, since the protective plate 80 is relatively soft, the protective plate 80 can easily fit to the table portion 70 and the table liner 60.

[0074] Furthermore, in this embodiment, the protective plate 80 is made of a material having a lower tensile strength than the support surface 73 of the table portion 70. This makes it possible to suppress wear on the support surface 73 of the table portion 70.

[0075] Furthermore, in this embodiment, the protective plate 80 is made of a material with sufficient compressive strength to not be deformed by the load from the crushing roller 13. This makes it possible to suppress deformation of the protective plate 80 due to the load from the crushing roller 13. Therefore, it is possible to make it less likely that problems will occur in the crushing table 12 due to deformation of the protective plate 80.

[0076] In this embodiment, the protective plate 80 is installed so that the upper surface of the protective plate 80 is flush with the area of ​​the support surface 73 where the recesses 74 are not formed. In other words, the protective plate 80 is installed so that the height position of the upper surface of the protective plate 80 installed on the support surface 73 is the same as the height position of the support surface 73 before the repair process. As a result, the height position of the upper surface of the installed protective plate 80 is the same as the height position of the support surface 73 before the repair process. Therefore, the height position at which the table liner 60 is installed can be the same before and after the repair. Therefore, there is no need to prepare table liners 60 of different shapes according to the amount of processing during repair. Therefore, it is sufficient to manufacture table liners 60 of the same shape, which improves the productivity of the table liner 60.

[0077] The height position of the support surface 73 before the repair process may be the height position of the support surface 73 immediately before the repair process, or the height position of the support surface 73 before the support surface 73 deteriorates (for example, the height position of the support surface 73 of the table portion 70 before use, or the height position of the support surface 73 at the time of design, etc.). Furthermore, the repair of the support surface 73 performed in the repair process may be, for example, a repair that changes the height position of the support surface 73, such as a process of cutting the support surface 73. The process of cutting the support surface 73 may be, for example, a process of removing irregularities formed on the support surface 73 by cutting.

[0078] The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure. The solid fuel used is not limited to that disclosed herein, and may be coal, biomass fuel, petroleum coke (PC), etc. Furthermore, these solid fuels may be used in combination.

[0079] Furthermore, in the above embodiment, an example has been described in which the protection plate 80 is formed of a single annular plate, but the present disclosure is not limited to this. For example, in consideration of ease of transport into the housing 11 of the mill 10, the protective plate 80 may be divided into pieces of a size that can be transported. The divided protective plates (hereinafter referred to as "divided protective plates") are arranged side by side in the circumferential direction. Note that there may be gaps between adjacent divided protective plates. Furthermore, adjacent divided protective plates may or may not be fixed to each other. The divided protective plates may be fixed to the table portion 70 or the table liner 60 as necessary.

[0080] The milling table, the solid fuel milling device, and the milling table repair method described in the above-described embodiments can be understood, for example, as follows. The grinding table according to the first aspect of the present disclosure is a grinding table (12) that grinds the material to be ground by sandwiching it between the grinding roller (13) and the table liner (60) that grinds the material to be ground on its upper surface, a table portion (70) having a support surface (73) that supports the table liner (60) from below, and a protective plate (80) that is provided between the table liner (60) and the table portion (70) and covers the support surface (73), and the protective plate (80) is made of a material that is less hard than the support surface (73) of the table portion (70).

[0081] In the above configuration, the support surface is covered with a protective plate made of a material with a lower hardness than the support surface of the table. This allows the protective plate to actively absorb wear caused by friction between the protective plate and the table, wear caused by foreign matter that has entered between the protective plate and the table, etc. In other words, the protective plate wears out before the support surface of the table. This makes it possible to suppress wear on the support surface of the table.

[0082] Furthermore, wear on the support surface of the table can be suppressed, making it difficult for unevenness to form on the support surface. This makes it difficult for localized loads to act on the table liner supported by the support surface, thereby suppressing damage to the table liner.

[0083] Furthermore, since the protective plate is relatively soft, the protective plate can easily fit to the table portion and the table liner.

[0084] Furthermore, in the grinding table according to a second aspect of the present disclosure, in the first aspect, the protective plate (80) is formed of a material having a lower tensile strength than the support surface (73) of the table portion (70).

[0085] In the above configuration, the protective plate is made of a material having a lower tensile strength than the support surface of the table, thereby making it possible to suppress wear on the support surface of the table.

[0086] In addition, the grinding table according to a third aspect of the present disclosure is the grinding table according to the first or second aspect, wherein the protective plate (80) is formed of a material having a compressive strength that does not deform due to the load from the grinding roller (13).

[0087] In the above configuration, the protective plate is made of a material with sufficient compressive strength to withstand the load from the crushing roller. This makes it possible to suppress deformation of the protective plate due to the load from the crushing roller. Therefore, it is possible to reduce the occurrence of problems with the crushing table due to deformation of the protective plate. Note that deformation here refers to deformation that significantly impairs the function of the grinding table. Therefore, the phrase "does not deform" in the above configuration includes slight deformation of the protective plate that does not impair the function of the grinding table.

[0088] Moreover, a solid fuel pulverizer according to a first aspect of the present disclosure includes the pulverizing table (12) according to any one of the first to third aspects.

[0089] Furthermore, the method for repairing a grinding table according to the first aspect of the present disclosure is a method for repairing a grinding table (12) that grinds an object to be ground by sandwiching the object between the grinding table (12) and a grinding roller (13), wherein the grinding table (12) has a table liner (60) that grinds the object to be ground on its upper surface, and a table portion (70) having a support surface (73) that supports the table liner (60) from below, and the method includes a removal step of removing the table liner (60) from the table portion (70), a repair step of repairing the support surface (73) after the removal step so that the support surface (73) becomes flat, and an installation step of installing a protective plate (80) made of a material that is less hard than the support surface (73) of the table portion (70) so as to cover at least a portion of the support surface (73) after the repair step.

[0090] Furthermore, in the method for repairing a grinding table according to a second aspect of the present disclosure, in the above-mentioned first aspect, the installation step installs the protective plate (80) so that the height position of the upper surface of the protective plate (80) installed on the support surface (73) is the same height position as the height position of the support surface (73) before the repair step.

[0091] In the above configuration, the protective plate is installed so that the height position of the upper surface of the protective plate installed on the support surface is the same as the height position of the support surface before the repair process. As a result, the height position of the upper surface of the installed protective plate is the same as the height position of the support surface before the repair process. Therefore, the height position at which the table liner is installed can be the same before and after repair. Therefore, there is no need to prepare table liners of different shapes according to the amount of processing during repair. Therefore, it is sufficient to manufacture table liners of the same shape, which improves the productivity of table liner production.

[0092] The height position of the support surface before the repair process may be the height position of the support surface immediately before the repair process, or the height position of the support surface before the support surface deteriorated (for example, the height position of the support surface of the table part before use, or the height position of the support surface at the time of design, etc.). Furthermore, the repair of the support surface performed in the repair process may be, for example, a repair that changes the height position of the support surface, such as a process of cutting the support surface. The process of cutting the support surface may be, for example, a process of removing irregularities formed on the support surface by cutting.

[0093] Furthermore, the grinding table repair method according to a third aspect of the present disclosure includes, in the second aspect, a protective plate (80) manufacturing step of manufacturing the protective plate (80) so that the height position of the upper surface of the protective plate (80) installed on the support surface (73) is the same as the height position of the support surface (73) before the repair step.

[0094] The above-described configuration includes a protective plate manufacturing process for manufacturing a protective plate so that the height position of the upper surface of the protective plate installed on the support surface is the same as the height position of the support surface before the repair process. This allows the protective plate to be installed so that the height position of the upper surface of the protective plate is the same as the height position of the support surface before the repair process.

[0095] Furthermore, in a method for repairing a grinding table according to a fourth aspect of the present disclosure, in the second aspect described above, the repairing step repairs the support surface (73) so that the height position of the upper surface of the protective plate (80) installed on the support surface (73) is the same height position as the height position of the support surface (73) before the repairing step.

[0096] In the above configuration, in the repair process, the support surface is repaired so that the height position of the upper surface of the protective plate installed on the support surface is the same as the height position of the support surface before the repair process. This allows the protective plate to be installed so that the height position of the upper surface of the protective plate is the same as the height position of the support surface before the repair process. [Explanation of symbols]

[0097] 1: Power plant 10: Mill 11: Housing 12: Grinding table 13: Crushing roller 14:Reducer 15: Mill motor 16: Rotary classifier 16a: Blade 17: Coal feed pipe 18: Classifier motor 19: Exit port 21: Banka 22: Downspout section 25:Coal feeding machine 26: Transport unit 27: Coal feeder motor 30: Blower 30a: Hot gas flow path 30b: Cold gas flow path 30c: Thermal gas damper 30d: Cold gas damper 31: Primary air ventilator 34: Air preheater 40: Status detection unit 41: Bottom part 42: Ceiling 45: Journal head 46: Pressing device 47: Support arm 48: Support shaft 50: Control unit 60: Table liner 61:Top surface 62: Bottom surface 63: Keyway 70: Table section 71: Base 72: Wall part 73: Support surface 74: Recess 75: Keyway 80: Protective plate 81: Keyhole 90: Key 100: Solid fuel crusher 110: Primary air flow path 120: Fine powder fuel supply pipe 130: Cutting equipment 131: Turning tool 132: Horizontal rail 133: Vertical rail 140: Milling machine 141: Cutter 142: Arm part 143: Moving section 200: Boiler 210: Furnace 220: Burner

Claims

1. A crushing table crushes an object to be crushed by sandwiching the object between the crushing roller and the crushing table, a table liner that crushes the object to be crushed on its upper surface; a table portion having a support surface that supports the table liner from below; a protective plate provided between the table liner and the table portion and covering the support surface; The protection plate is made of a material having a lower hardness than the support surface of the table portion.

2. 2. The grinding table according to claim 1, wherein the protective plate is made of a material having a lower tensile strength than the support surface of the table portion.

3. 2. The grinding table according to claim 1, wherein the protective plate is made of a material having sufficient compressive strength to not be deformed by the load from the grinding roller.

4. A solid fuel pulverizer comprising the pulverizing table according to any one of claims 1 to 3.

5. A method for repairing a crushing table that crushes objects by sandwiching the objects between the crushing table and a crushing roller, comprising: The crushing table has a table liner that crushes the object to be crushed on its upper surface, and a table portion having a support surface that supports the table liner from below, a removing step of removing the table liner from the table portion; a repairing step of repairing the support surface so that the support surface becomes flat after the removing step; an installation step of installing, after the repair step, a protective plate formed of a material having a lower hardness than the support surface of the table portion so as to cover at least a portion of the support surface.

6. The grinding table repair method according to claim 5, wherein the installation step installs the protective plate so that the height position of the upper surface of the protective plate installed on the support surface is the same height position as the height position of the support surface before the repair step.

7. 7. The grinding table repair method according to claim 6, further comprising a protective plate manufacturing process of manufacturing the protective plate so that the height position of the upper surface of the protective plate installed on the support surface is the same height position as the height position of the support surface before the repair process.

8. 7. The method for repairing a grinding table according to claim 6, wherein the repairing step repairs the support surface so that the height position of the upper surface of the protective plate installed on the support surface is the same height position as the height position of the support surface before the repairing step.

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