Roller cover and crusher, and design method for roller cover and design method for crusher

Abstract

To provide a roller cover which does not reduce lives of components and a crushing machine, and to provide a roller cover design method and a crushing machine design method.SOLUTION: A roller cover 70 forms an outer wall of a crushing machine configured to crush a solid fuel and includes an attachment wall body 71 to which a hydraulic cylinder 61 configured to apply a crushing load to a support arm connected to a crushing roller is attached by an attachment part 72. In the attachment wall body 71, a first area R1 in which rigidity is substantially constant is provided over an entire peripheral direction around the attachment part 72. Further, an accumulator 65 which absorbs vibration of the hydraulic cylinder 61 having a predetermined frequency or a lower frequency through suction and discharge of a hydraulic oil is connected to the hydraulic cylinder 61. The attachment wall body 71 has spring characteristics which absorb vibration having a frequency exceeding the predetermined frequency.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a roller cover, a pulverizer, a roller cover design method, and a pulverizer design method.

Background Art

[0002] A pulverizer such as a vertical mill is configured to pulverize supplied raw materials such as biomass pellets and coal by pressing a rotatably supported pulverizing roller against a power-driven rotating pulverizing table (for example, Patent Document 1).

[0003] The pulverizing roller is installed so as to be vertically swingable relative to the housing via a journal head. At this time, a load for pulverizing the raw material (pulverizing load) is applied to the pulverizing roller by a load applying device such as a hydraulic cylinder via the journal head. The load applying device is connected to, for example, a roller cover that forms the outer wall of the pulverizer and covers the journal head.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] When pulverizing raw materials, the pulverizing roller may move up and down due to changes in the thickness of the raw material layer on the pulverizing table, biting of foreign matter, and the like. In addition, the vertical movement propagates to the load applying device such as a hydraulic cylinder via the journal head.

[0006] When the load-applying device is a hydraulic cylinder, the vertical movement of the crushing roller is converted into the reciprocating motion of the hydraulic cylinder rod via the journal head. As the rod reciprocates, hydraulic fluid enters and exits the hydraulic cylinder. Normally, the entering and exiting hydraulic fluid is drawn in / discharged to an accumulator connected to the hydraulic cylinder, and the pressure is kept approximately constant to suppress pulsation of the hydraulic fluid and prevent hammering and cavitation.

[0007] The accumulator is connected to the hydraulic cylinder via an oil port. Typically, the diameter of the oil port is considerably smaller than the inner diameter of the hydraulic cylinder or the accumulator. Furthermore, because a poppet valve and its associated mechanisms are installed in this oil port, the cross-sectional area of ​​the hydraulic fluid flow path within the oil port is quite small. Therefore, if the crushing roller moves up and down suddenly and abruptly due to, for example, foreign matter getting caught, the flow velocity of the hydraulic fluid through the oil port becomes extremely high, and the accumulator's intake / discharge of the hydraulic fluid cannot keep up, resulting in a large pressure loss. This pressure loss causes fluctuations in hydraulic pressure, and large and abrupt fluctuations in hydraulic pressure can cause hammering and cavitation, which can lead to fatigue of hydraulic fluid piping and other components. Furthermore, fluctuations in hydraulic pressure can cause excessive impact loads and high stress on components that transmit the crushing load, such as the crushing roller, housing, crushing table, reducer, and roller cover, which is one of the factors that shortens the lifespan of these components.

[0008] This disclosure is made in view of these circumstances and aims to provide a roller cover and a crusher that do not shorten the lifespan of the parts, as well as a method for designing the roller cover and the crusher. [Means for solving the problem]

[0009] To solve the above problems, the roller cover and crusher, as well as the design method for the roller cover and the design method for the crusher, of this disclosure employ the following means. In other words, a roller cover according to one aspect of the present disclosure is a roller cover that forms the outer wall of a crusher for crushing solid fuel, and comprises a mounting wall body to which a hydraulic cylinder that applies a crushing load to an arm portion connected to a crushing roller is connected at a mounting portion, and the mounting wall body is provided with a first region having substantially constant rigidity extending in the circumferential direction around the mounting portion.

[0010] Furthermore, a crusher according to one aspect of the present disclosure comprises a roller cover and a housing to which the roller cover is attached, wherein the housing has spring characteristics that absorb vibrations of a frequency exceeding the predetermined frequency.

[0011] Furthermore, a roller cover design method according to one aspect of the present disclosure is a roller cover that forms the outer wall of a crusher for crushing solid fuel, wherein the roller cover comprises a mounting wall body to which a hydraulic cylinder that applies a crushing load to an arm portion connected to a crushing roller is connected at a mounting portion, and a first region having substantially constant rigidity in the circumferential direction around the mounting portion is set in the mounting wall body.

[0012] Furthermore, a design method for a pulverizer according to one aspect of the present disclosure comprises a hydraulic cylinder that applies a pulverizing load to an arm connected to a pulverizing roller, a roller cover having a mounting wall to which the hydraulic cylinder is connected, a housing to which the roller cover is attached, and an accumulator connected to the hydraulic cylinder that absorbs vibrations of the hydraulic cylinder below a predetermined frequency by suction and discharge of hydraulic fluid, wherein the mounting wall has spring characteristics that absorb vibrations at frequencies exceeding the predetermined frequency, and the housing has spring characteristics that absorb vibrations at frequencies exceeding the predetermined frequency. [Effects of the Invention]

[0013] This disclosure provides a roller cover and a crusher that do not shorten the lifespan of the parts, as well as a method for designing the roller cover and a method for designing the crusher. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic configuration diagram of a power generation plant according to an embodiment of the present disclosure. [Figure 2] This is a schematic vertical cross-sectional view of a mill. [Figure 3] This is a front view of the roller cover as viewed from the direction of arrow A shown in Figure 2. [Figure 4] This is a perspective view of the roller cover shown in Figure 3. [Figure 5] This is a front view of a roller cover as a comparative example. [Figure 6] This is a diagram showing the propagation of vibration from the input through the accumulator and the roller cover to the crusher. [Figure 7] This is a perspective view of a journal head. [Figure 8] This is a side view of the roller cover shown in Figure 3. [Figure 9] This is a front view of a roller cover according to a modified example. [Figure 10] This is a schematic perspective view showing deformation of a housing. [Figure 11] This is a diagram showing the propagation of vibration from the input through the accumulator, the roller cover and the housing to the crusher. [Modes for Carrying Out the Invention]

[0015] [First Embodiment] Hereinafter, the roller cover, the crusher, the design method of the roller cover, and the design method of the crusher according to the first embodiment of the present disclosure will be described with reference to the drawings.

[0016] [Regarding Configuration of Power Generation Plant] As shown in Figure 1, the power generation plant 1 includes a solid fuel crushing device 100 and a boiler 200. In the following description, "upper" refers to the vertically upward direction, and terms with the character "upper" such as upper part and upper surface refer to the vertically upward portion. Similarly, "lower" refers to the vertically downward portion, and the vertical direction is not strictly defined and includes errors.

[0017] The solid fuel crushing apparatus 100 of this embodiment is a device that crushes solid fuels such as biomass fuel or coal to produce fine fuel powder, which is then supplied to the burner (combustion device) 220 of the boiler 200. The power plant 1 shown in Figure 1, which includes a solid fuel grinder 100 and a boiler 200, is equipped with one solid fuel grinder 100, but it may also be a system equipped with multiple solid fuel grinders 100, each corresponding to one of the multiple burners 220 of a single boiler 200.

[0018] The solid fuel crushing apparatus 100 of this embodiment includes a mill (crusher) 10, a bunker (storage unit) 21, a coal feeder (fuel supply unit) 25, a blower (conveyor gas supply unit) 30, a state detection unit 40, and a control unit 50.

[0019] The mill 10, which grinds solid fuels such as coal and biomass fuel supplied to the boiler 200 into finely powdered solid fuel, may be configured to grind only coal, only biomass fuel, or both coal and biomass fuel. Here, biomass fuel refers to renewable, biologically derived organic resources, such as thinned timber, waste wood, driftwood, grass, waste materials, sludge, tires, and recycled fuels (pellets and chips) made from these materials, and is not limited to those listed here. Because biomass fuels absorb carbon dioxide during the growth process of biomass, they do not emit carbon dioxide, which is a greenhouse gas, and are therefore considered carbon neutral, and their use is being explored in various ways.

[0020] The mill 10 comprises a housing 11, a grinding table 12, a grinding roller 13, a reduction gear (drive transmission unit) 14, a mill motor (drive unit) 15 connected to the reduction gear 14 and rotatingly driving the grinding table 12, a rotary classifier (classification unit) 16, a coal supply pipe (fuel supply unit) 17, and a classifier motor 18 that rotately drives the rotary classifier 16.

[0021] The housing 11 is a cylindrical enclosure with an axis Ch extending in the vertical direction as its central axis, and houses the crushing table 12, the crushing rollers 13, the rotary classifier 16, and the coal supply pipe 17.

[0022] As shown in Figure 2, an opening 11a is formed in the peripheral wall of the housing 11, and a grinding roller 13 and a journal head 45 that supports the grinding roller 13 are installed near the opening 11a. With the crushing rollers 13 and the like installed, the opening 11a is covered by the roller cover 70, which together with the housing 11 forms the outer wall of the mill 10.

[0023] As shown in Figure 1, a coal supply pipe 17 is installed in the center of the ceiling portion 42 of the housing 11. This coal supply pipe 17 supplies solid fuel, which has been guided from the bunker 21 via the coal feeder 25, into the housing 11. It is positioned vertically at the center of the housing 11, and its lower end extends into the interior of the housing 11.

[0024] A reduction gear 14 is installed near the bottom surface 41 of the housing 11, and a grinding table 12 that rotates around an axis Ch by the driving force transmitted from a mill motor 15 connected to this reduction gear 14 is rotatably positioned. The crushing table 12 is a circular member in plan view, and is positioned so that the lower ends of the coal supply pipe 17 face each other. The upper surface of the crushing table 12 may have a sloping shape, for example, with the center being lower and the outer surface becoming higher towards the outside, and the outer circumference being bent upward. The coal supply pipe 17 supplies solid fuel (for example, coal or biomass fuel in this embodiment) from above to the crushing table 12 below, and the crushing table 12 crushes the supplied solid fuel by sandwiching it between the crushing rollers 13.

[0025] When solid fuel is fed from the coal supply pipe 17 toward the center of the crushing table 12, the centrifugal force from the rotation of the crushing table 12 guides the solid fuel toward the outer periphery of the crushing table 12, where it is crushed between the crushing table 12 and the crushing rollers 13. The crushed solid fuel is guided from the conveying gas passage (hereinafter referred to as the primary air passage) 110 and blown upward by the conveying gas (hereinafter referred to as "primary air") blown out from the conveying gas outlet (outlet) 12b, and is guided to the rotary classifier 16.

[0026] As shown in Figure 2, an outlet 12b is provided between the outer surface of the grinding table 12 and the inner surface of the housing 11, which allows primary air flowing in from the primary air passage 110 to flow out into the space above the grinding table 12 inside the housing 11. A swirling blade 12a is installed on the outer circumference of the crushing table 12 located at the outlet of the outlet 12b, and imparts a swirling force to the primary air blown upward from the outlet 12b. The primary air, given a swirling force by the swirling blade 12a, becomes an airflow with a swirling velocity component, and conveys the solid fuel crushed on the crushing table 12 to the rotary classifier 16 located above in the housing 11. Of the crushed solid fuel, those larger than a predetermined particle size are classified by the rotary classifier 16, or they fall without reaching the rotary classifier 16 and are returned to the crushing table 12, where they are crushed again between the crushing table 12 and the crushing roller 13.

[0027] As shown in Figures 1 and 2, the crushing roller 13 is a rotating body that crushes the solid fuel supplied from the coal supply pipe 17 onto the crushing table 12. The crushing roller 13 is pressed against the upper surface of the crushing table 12 and works in cooperation with the crushing table 12 to crush the solid fuel. Although only one grinding roller 13 is shown as a representative example in Figure 1, multiple grinding rollers 13 are arranged at regular intervals in the circumferential direction to press against the upper surface of the grinding table 12. For example, three grinding rollers 13 are arranged at equal intervals in the circumferential direction with a 120° angle interval on the outer circumference. In this case, the portions of the three grinding rollers 13 that contact (press) the upper surface of the grinding table 12 are at equal distances from the rotational axis of the grinding table 12. In addition, three openings 11a are formed in the housing 11 at equal intervals in the circumferential direction.

[0028] The crushing roller 13 is supported by a journal head 45 having a support arm 47 (arm portion) and a support shaft 48. The grinding roller 13, supported by the journal head 45, can swing and displace vertically as the journal head 45 rotates around a horizontally extending support shaft 48, allowing it to move closer to and further away from the upper surface of the grinding table 12. The crushing roller 13 is configured such that its outer surface is in contact with the solid fuel on the upper surface of the crushing table 12, and as the crushing table 12 rotates, it receives rotational force from the crushing table 12 and rotates along with it. When solid fuel is supplied from the coal supply pipe 17, it is crushed by being pressed between the crushing roller 13 and the crushing table 12. This pressing force is called the crushing load.

[0029] The upper end of the support arm 47 of the journal head 45 (at least the portion above the support shaft 48) is in contact with the intermediate piston 62 of the load-applying device 60. The load-applying device 60 is a device that applies a load (crushing load) to the support arm 47 so as to press the crushing roller 13 against the crushing table 12, and is fixed to the roller cover 70. The crushing load is applied, for example, by the hydraulic cylinder 61 of the load-applying device 60. Details of the load-applying device 60 will be described later.

[0030] A gap bolt 80 is in contact with the lower end of the support arm 47 of the journal head 45 (at least the portion below the support shaft 48). The gap bolt 80 is a device that provides a gap between the grinding roller 13 and the grinding table 12 so that the grinding roller 13 does not come into contact with the grinding table 12 when there is no solid fuel on the upper surface of the grinding table 12, and is fixed to the roller cover 70. The dimensions of the gap are determined by the amount the gap bolt 80 protrudes.

[0031] The reduction gear 14 is connected to the 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.

[0032] The rotary classifier (classification unit) 16 is located on the upper part of the housing 11 and has a hollow, inverted conical outer shape. The rotary classifier 16 is equipped with a plurality of blades 16a extending vertically at its outer circumference. Each blade 16a is provided at a predetermined interval (equal intervals) around the central axis of the rotary classifier 16. The rotary classifier 16 is a device that classifies solid fuel crushed by the crushing table 12 and crushing rollers 13 (hereinafter, the crushed solid fuel will be referred to as "crushed fuel") into particles larger than a predetermined particle size (for example, 70-100 μm for coal) (hereinafter, crushed fuel with a particle size exceeding the predetermined particle size will be referred to as "coarse powder fuel") and particles smaller than or equal to the predetermined particle size (hereinafter, crushed fuel with a particle size smaller than or equal to the predetermined particle size will be referred to as "fine powder fuel"). The rotary classifier 16 is driven by a classifier motor 18 controlled by the control unit 50, and rotates around the coal supply pipe 17 on a cylindrical shaft (not shown) that extends vertically in the housing 11. Furthermore, a fixed classifier may be used as the classification unit, which has a fixed, hollow, inverted cone-shaped casing and a plurality of fixed swivel blades instead of blades 16a on the outer circumference of the casing.

[0033] The crushed fuel that reaches the rotary classifier 16 is subjected to a relative balance between the centrifugal force generated by the rotation of the blades 16a and the centripetal force from the airflow of the primary air. Larger diameter coarse fuel particles are knocked off by the blades 16a and returned to the crushing table 12 for further crushing, while the fine fuel particles are guided to the outlet port 19 located in the ceiling 42 of the housing 11. The fine fuel particles classified by the rotary classifier 16 are discharged along with the primary air from the outlet port 19 into the fine fuel supply channel (fine fuel supply pipe) 120 and supplied to the burner 220 of the boiler 200.

[0034] The coal supply pipe 17 is installed so as to extend vertically through the ceiling portion 42 of the housing 11, with its lower end extending into the interior of the housing 11, and supplies solid fuel fed from the top of the coal supply pipe 17 to the center of the crushing table 12. A coal feeder 25 is connected to the upper end of the coal supply pipe 17, and solid fuel is supplied to it.

[0035] The coal feeder 25 is connected to the bunker 21 by a downspout section 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 solid fuel from the bunker 21 may be provided in the middle of the downspout section 22. The coal feeder 25 comprises a conveying unit 26 and a coal feeder motor 27. The conveying unit 26 is, for example, a belt conveyor, which, driven by the coal feeder motor 27, conveys the solid fuel discharged from the lower end of the downspout unit 22 to the upper part of the coal supply pipe 17 and feeds it into the mill. 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 moving speed of the belt conveyor of the conveying unit 26.

[0036] Typically, the mill 10 is supplied with primary air to transport the fine fuel to the burner 220, and the pressure inside is higher than that of the coal feeder 25 and bunker 21. The inside of the downspout section 22, which connects the bunker 21 and the coal feeder 25, is a layered structure of fuel. This solid fuel layer ensures a sealing effect (material seal) that prevents backflow of primary air and pulverized fuel from the mill 10 to the bunker 21.

[0037] The blower unit 30 is a device that blows primary air into the housing 11 to dry the crushed fuel and to transport it to the rotary classifier 16. In this embodiment, the blower unit 30 includes a primary air fan (PAF) 31, a hot gas passage 30a, a cold gas passage 30b, a hot gas damper 30c, and a cold gas damper 30d in order to appropriately adjust the flow rate and temperature of the primary air blown into the housing 11.

[0038] The hot gas passage 30a supplies a portion of the air sent from the primary air ventilator 31 as hot gas that has been heated by passing it through the air preheater (heat exchanger) 34. A hot gas damper 30c is provided in the hot gas passage 30a. The opening degree of the thermal gas damper 30c is controlled by the control unit 50. The opening degree of the thermal gas damper 30c determines the flow rate of the thermal gas supplied from the thermal gas flow path 30a.

[0039] The cold gas passage 30b supplies a portion of the air discharged from the primary air ventilator 31 as cold gas at room temperature. A cold gas damper 30d is provided in the cold gas passage 30b. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The opening degree of the cold gas damper 30d determines the flow rate of cold gas supplied from the cold gas flow path 30b.

[0040] In this embodiment, the flow rate of the primary air is the sum of the flow rate of the hot gas supplied from the hot gas channel 30a and the flow rate of the cold gas supplied from the cold gas channel 30b. The temperature of the primary air is determined by the mixing ratio of the hot gas supplied from the hot gas channel 30a and the cold gas supplied from the cold gas channel 30b, and is controlled by the control unit 50. Furthermore, the oxygen concentration in the primary air blown into the housing 11 from the primary air passage 110 may be adjusted by introducing a portion of the combustion gas discharged from the boiler 200 by, for example, a gas recirculation ventilator (not shown) into the hot gas supplied from the hot gas passage 30a and mixing it. By adjusting the oxygen concentration in the primary air, for example, when using a highly ignitable (easily ignited) solid fuel, it is possible to suppress the ignition of the solid fuel in the path from the mill 10 to the burner 220.

[0041] The 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 is, for example, a differential pressure measuring means, which measures the differential pressure of the mill 10 between the pressure at the point where primary air flows from the primary air passage 110 into the inside of the housing 11 and the pressure at the outlet port 19 where primary air and fine fuel are discharged from inside the housing 11 to the fine fuel supply pipe 120. The 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 and the vicinity of the pulverizing table 12 inside the housing 11 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 this differential pressure of the mill 10, the amount and particle size range of the fine fuel discharged from the outlet port 19 can be adjusted. This allows for a stable supply of an amount of fine fuel corresponding to the amount of solid fuel supplied to the mill 10 to the burner 220 installed in the boiler 200, while maintaining the particle size of the fine fuel within a range that does not affect the combustibility of the solid fuel in the burner 220. Furthermore, the state detection unit 40 is, for example, a temperature measuring means, which detects the temperature of the primary air supplied into the housing 11 (primary air temperature at the mill inlet) and the temperature of the mixed gas of primary air and fine fuel at the outlet port 19 (primary air temperature at the mill outlet), and controls the air blower 30 so that the respective upper limits are not exceeded. Each upper limit temperature is determined considering the possibility of ignition according to the properties of the solid fuel. Note that the primary air is cooled inside the housing 11 as the crushed fuel is dried and transported, so the primary air temperature at the mill inlet is, for example, around 300 degrees Celsius from room temperature, and the primary air temperature at the mill outlet is, for example, around 90 degrees Celsius from room temperature.

[0042] The control unit 50 is a device that controls each part of the solid fuel crushing apparatus 100. The control unit 50 may, for example, transmit a drive command to the mill motor 15 to control the rotation speed of the grinding table 12. The control unit 50, for example, transmits a drive command to the classifier motor 18 to control the rotational speed of the rotary classifier 16 and adjust the classification performance, thereby maintaining the particle size of the fine fuel within a range that does not affect the combustibility of the solid fuel in the burner 220, and stably supplying an amount of fine fuel corresponding to the amount of solid fuel supplied to the mill 10 to the burner 220. Furthermore, the control unit 50 can adjust the amount of solid fuel supplied to the mill 10 (coal supply amount) by, for example, transmitting a drive instruction to the coal feeder motor 27. 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 into the housing 11 and the temperature of the primary air at the outlet port 19 (mill outlet primary air temperature) are set to predetermined values ​​corresponding to the amount of coal supplied for each type of solid fuel. Note that the control of the primary air temperature may also be performed with respect to the temperature at the mill inlet (mill inlet primary air temperature).

[0043] The control unit 50 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in the ROM or other storage medium, provided in a state where it is stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory. HDDs may be replaced with solid-state disks (SSDs), etc.

[0044] Next, a boiler 200 that generates steam by burning fine fuel supplied from a solid fuel crushing device 100 will be described. The boiler 200 is equipped with a furnace 210 and a burner 220.

[0045] The burner 220 is a device that burns the 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 outside air (forced draft fan) 32 in an air preheater 34. The combustion of the pulverized fuel takes place in the furnace 210, and the high-temperature combustion gas is discharged to the outside of the boiler 200 after passing through heat exchangers such as evaporators, superheaters, and economizers (not shown).

[0046] The combustion gas discharged from the boiler 200 undergoes predetermined treatment in environmental equipment (denitrification equipment, dust collector, desulfurization equipment, etc., not shown), and heat exchange with primary and secondary air takes place in the air preheater 34. The gas is then guided to the chimney (not shown) via the induced draft fan (IDF) 33 and released into the outside air. The air heated by the combustion gas in the air preheater 34 and sent out from the primary air fan 31 is supplied to the aforementioned hot gas flow path 30a. The feedwater to each heat exchanger of the boiler 200 is heated in an economizer (not shown), then further heated in an evaporator (not shown) and a superheater (not shown) to generate high-temperature, high-pressure superheated steam, which is sent to a steam turbine (not shown), which is the power generation unit, to rotate the steam turbine, and then rotates a generator (not shown) connected to the steam turbine to generate electricity, thus constituting the power plant 1.

[0047] [Regarding load-bearing devices and roller covers] As shown in Figure 2, the load application device 60 is a device that applies a crushing load along the axis Cf to the upper end of the support arm 47. The load-applying device 60 includes a hydraulic cylinder 61, an intermediate piston 62, and a piston housing 63. The operating force generated by the hydraulic cylinder 61 is transmitted from the rod 61a of the hydraulic cylinder 61 to the upper end of the support arm 47 via the intermediate piston 62, which is housed in the piston housing 63 and is slidable along the direction of the axis Cf.

[0048] An accumulator 65 is connected to the hydraulic cylinder 61 via an oil port 65a. The vertical movement of the crushing roller 13 is converted into the reciprocating motion of the rod 61a of the hydraulic cylinder 61 via the support arm 47 of the journal head 45. When the rod 61a reciprocates, hydraulic fluid enters and leaves the hydraulic cylinder 61. The accumulator 65 is a device that sucks in and discharges the hydraulic fluid entering and leaving the hydraulic cylinder 61, and has the function of suppressing pulsation by keeping the pressure of the hydraulic fluid in the hydraulic cylinder 61 approximately constant to prevent hammering and cavitation.

[0049] Generally, the flow rate of hydraulic fluid in oil port 65a is approximately 1000 L / min to 2000 L / min. Here, assuming an average hydraulic fluid flow rate of 1500 L / min and a cylinder diameter of φ300 mm for the hydraulic cylinder 61, the maximum stroke speed that this hydraulic cylinder 61 can achieve is approximately 350 mm / s. When the stroke of the rod 61a is 10 mm, the frequency of vibrations (reciprocating motion of the rod 61a) that the accumulator 65 can absorb is approximately 17.5 Hz (350 mm / s ÷ 10 mm ÷ 2 (for reciprocating motion)). In other words, the accumulator 65 can absorb hydraulic fluid pulsations caused by vibrations up to 17.5 Hz. On the other hand, hydraulic fluid pulsations caused by vibrations exceeding this frequency cannot be absorbed by the accumulator 65, resulting in fluctuations in the hydraulic fluid pressure. Large and sudden fluctuations in hydraulic pressure can cause hammering and cavitation, leading to fatigue of hydraulic fluid piping and other components. Furthermore, fluctuations in hydraulic fluid pressure can cause excessive impact loads and high stress on components such as the roller cover 70 and piston housing 63.

[0050] Please note that the above figures are merely examples, and the vibration frequencies that can be absorbed will vary depending on the specifications of the Accumulator 65. However, in either case, the limitations of the oil port 65a limit the frequency of vibrations that can be absorbed by the accumulator 65. In light of these circumstances, the design frequency for which absorption by the accumulator 65 is assumed is typically up to about 20 Hz.

[0051] The hydraulic cylinder 61 of the load-applying device 60 configured as described above is attached to the mounting portion 72 of the wall (mounting wall 71) of the roller cover 70. Specifically, as shown in Figures 2 and 3, the piston housing 63, together with the flange 64, sandwiches the mounting portion 72 of the mounting wall 71 and is fastened with bolts 64a, thereby indirectly attaching the hydraulic cylinder 61 to the roller cover 70 via the piston housing 63. The method of attaching the hydraulic cylinder 61 to the roller cover 70 is not limited to the above-described configuration.

[0052] Here, the mounting portion 72 is a predetermined part of the mounting wall 71 to which the hydraulic cylinder 61 is directly or indirectly attached. In this embodiment, the hydraulic cylinder 61 is indirectly attached to the mounting wall 71 via the piston housing 63. The mounting portion 72 is the part of the mounting wall 71 sandwiched between the piston housing 63 and the flange 64.

[0053] As shown in Figure 2, the mounting wall 71 is a wall that is approximately perpendicular to the axis Cf. The mounting wall 71 also receives the force that the accumulator 65 could not absorb from the force that the hydraulic cylinder 61 receives from the support arm 47 via the intermediate piston 62 (including vibrations and shocks caused by the vertical movement of the crushing roller 13). At this time, the mounting portion 72 becomes the input point for this force.

[0054] In this embodiment, as shown in Figures 3 and 4, the mounting wall 71 is designed to be easily elastically deformed, without any structure intended to increase its rigidity (second moment of area). Specifically, a first region R1 (for example, the region inside the dashed line in Figure 3) is set up around the entire circumference of the mounting portion 72, and no structure intended to increase rigidity is provided in this first region R1. As a result, the mounting wall 71 becomes more susceptible to elastic deformation approximately uniformly around the entire circumference, at least in the first region R1, and the mounting wall 71 functions as a spring that absorbs vibrations and shocks caused by fluctuations in the force acting on the mounting portion 72. Furthermore, since the plate-shaped mounting wall 71 does not have any structures that restrict load propagation, such as the oil port 65a of the accumulator 65, a fast response to input is possible. Furthermore, "structures intended to increase rigidity" include, for example, ribs, but do not include parts where rigidity inevitably changes, such as bolt holes or suspension devices.

[0055] In this case, the spring characteristics set for the mounting wall 71 are configured to absorb vibrations at frequencies higher than those expected to be absorbed by the accumulator 65.

[0056] For example, if we consider the first region R1 as a circular region with a diameter of φ1200 mm centered on the axis Cf, and assume that the mounting wall 71 is made of 60 mm thick steel (SS400), and that a concentrated load is applied to the center of the first region R1, then the spring constant will be approximately 600 kN / mm. If we assume that the mass of the load-applying device 60 is 3000 kg, the natural frequency will be 72 Hz, and vibrations at a higher frequency than those expected to be absorbed by the accumulator 65 can be absorbed.

[0057] However, since the amplitude of vibrations that can be absorbed is smaller compared to the accumulator 65, it is preferable to adjust the amplitude that can be absorbed by the plate thickness of the mounting wall 71 and the area of ​​the first region R1, taking into consideration the rigidity and fatigue characteristics.

[0058] Figure 5 shows a roller cover 170 as a comparative example. The mounting wall 171 of the roller cover 170 has ribs 173 arranged radially around the mounting portion 172, intended to increase rigidity. Normally, as shown in Figure 5 of the roller cover 170, the rigidity of the mounting wall 171 is increased to suppress vibration.

[0059] As shown in Figure 6, the roller cover 70 is connected in series with the accumulator 65. In Figure 6, the width of the spring represents the amplitude it can absorb, and the height of the spring represents the frequency it can absorb. A thicker line represents a state where vibration is difficult to absorb. The width of the arrow represents the amplitude at that point, and the height of the arrow represents the frequency at that point. According to this, the accumulator 65 primarily absorbs vibrations with large amplitude and slow speed (low frequency vibrations) (see upper diagram in Figure 6). On the other hand, the roller cover 70 primarily absorbs vibrations with small amplitude and fast speed (high frequency vibrations) (see lower diagram in Figure 6). The combination of the accumulator 65 and the roller cover 70 is designed to efficiently absorb vibrations with a wide range of amplitudes and frequencies.

[0060] As mentioned above, the roller cover 70 deforms due to the vertical movement of the crushing roller 13. Therefore, if a lift meter for measuring the lift amount of the crushing roller 13 is connected to the roller cover 70 (especially the mounting wall 71), it may become impossible to accurately measure the lift amount of the crushing roller 13. Therefore, as shown in Figures 7 and 8, it is preferable to provide a lift meter 90 on the end face of the support shaft 48 that protrudes from the side of the housing 11 and the roller cover 70. The lift meter 90 detects, for example, the rotation of the support shaft 48 of the journal head 45, which is linked to the vertical movement of the mill 10, as the lift amount of the grinding roller 13. The dashed lines in Figure 7 represent the boundary between the housing 11 and the roller cover 70 and the outside.

[0061] <Variation> As shown in Figure 9, the stiffness and fatigue characteristics may be varied between the circular first region R1 and the surrounding second region R2. Specifically, the stiffness of the first region R1 may be reduced and its fatigue characteristics may be improved compared to the second region R2. This can be achieved, for example, by using different materials for the portion defining the first region R1 and the portion defining region 2 in the mounting wall 71. This makes it possible to efficiently absorb vibrations and shocks associated with vibrations in the first region R1, which is directly subjected to the load from the hydraulic cylinder 61, while reducing the possibility of damage due to fatigue.

[0062] This embodiment provides the following effects. Since the mounting wall 71 has a first region R1 with substantially constant rigidity that extends around the entire circumference of the mounting portion 72, the first region R1 (mounting wall 71) can be considered as a spring that uniformly absorbs vibrations and shocks caused by fluctuations in the force that the hydraulic cylinder 61 receives from the support arm 47, all around the circumference. Therefore, for example, the first region R1 (mounting wall 71) can absorb sudden vibrations and shocks caused by the rapid up-and-down movement of the crushing roller 13. This reduces the impact load and prevents a shortened lifespan of the parts. In addition, the ability of the grinding rollers 13 to follow changes in the thickness of the raw material layer on the grinding table 12 is improved, resulting in improved grinding performance.

[0063] Furthermore, since the mounting wall 71 has spring characteristics that allow it to absorb vibrations at frequencies exceeding those expected to be absorbed by the accumulator 65, it can absorb sudden vibrations and shocks associated with vibrations that are difficult to absorb by the accumulator 65.

[0064] Furthermore, since the first region R1 has lower rigidity and superior fatigue characteristics compared to the second region R2, it is possible to efficiently absorb vibrations and shocks associated with vibrations in the first region R1, which directly receives the load from the hydraulic cylinder 61, while reducing the possibility of damage due to fatigue.

[0065] Furthermore, since the first region R1 does not have ribs to suppress deformation, the rigidity around the first region R1 can be lowered compared to the case where ribs are provided.

[0066] [Second Embodiment] As shown in Figure 10, by actively omitting structures intended to increase rigidity from the housing 11, it is possible to maintain a minimum level of strength while making the housing 11 more susceptible to deformation by external forces. The dashed line in Figure 10 represents the housing 11 in an undeformed state. In this case, the spring characteristics set for the housing 11 are set to absorb vibrations at frequencies higher than those expected to be absorbed by the accumulator 65, similar to the mounting wall 71.

[0067] As a result, as shown in Figure 11, the combination of the accumulator 65, roller cover 70, and housing 11 can efficiently absorb vibrations of a wide range of amplitudes and frequencies.

[0068] This embodiment provides the following effects. Since the housing 11 has spring characteristics that allow it to absorb vibrations at frequencies exceeding those expected to be absorbed by the accumulator 65, it can also absorb sudden vibrations and shocks associated with vibrations that are difficult to absorb by the accumulator 65.

[0069] As described above, the roller cover and crusher according to this embodiment, as well as the design method for the roller cover and the design method for the crusher, can be understood, for example, as follows. A roller cover (70) according to a first aspect of the present disclosure is a roller cover (70) that forms the outer wall of a crusher (10) for crushing solid fuel, and comprises a mounting wall (71) to which a hydraulic cylinder (61) that applies a crushing load to an arm portion (47) connected to a crushing roller (13) is connected at a mounting portion (72), wherein the mounting wall (71) is provided with a first region (R1) having substantially constant rigidity extending in the circumferential direction around the mounting portion (72).

[0070] According to the roller cover (70) of this embodiment, the mounting wall (71) has a first region (R1) with substantially constant rigidity that extends around the entire circumference of the mounting portion (72). Therefore, the first region (R1) (mounting wall (71)) can be considered as a spring that uniformly absorbs vibrations and shocks associated with vibrations caused by fluctuations in the force that the hydraulic cylinder (61) receives from the arm portion (47) over the entire circumference. Therefore, for example, the first region (R1) (mounting wall (71)) can absorb sudden vibrations and shocks caused by the rapid up-and-down movement of the crushing roller (13). This reduces the impact load and prevents a shortened lifespan of the parts. In addition, the ability of the grinding rollers (13) to follow changes in the thickness of the raw material layer on the grinding table (12) is improved, resulting in improved grinding performance.

[0071] Furthermore, in the roller cover (70) according to the second aspect of this disclosure, in the first aspect, an accumulator (65) is connected to the hydraulic cylinder (61) to absorb vibrations of the hydraulic cylinder (61) below a predetermined frequency by the intake and discharge of hydraulic fluid, and the mounting wall (71) has spring characteristics to absorb vibrations at frequencies exceeding the predetermined frequency.

[0072] According to the roller cover (70) of this embodiment, an accumulator (65) is connected to the hydraulic cylinder (61) to absorb vibrations of the hydraulic cylinder (61) below a predetermined frequency by the intake and discharge of hydraulic fluid, and the mounting wall (71) has spring characteristics that absorb vibrations at frequencies above the predetermined frequency, so that the mounting wall (71) can absorb sudden vibrations and shocks associated with vibrations that are difficult to absorb by the accumulator (65).

[0073] Furthermore, in the third aspect of the present disclosure, the roller cover (70) is provided in the first or second aspect of the mounting wall (71) with a second area (R2) surrounding the first area (R1), wherein the first area (R1) has less rigidity and better fatigue characteristics than the second area (R2).

[0074] According to the roller cover (70) of this embodiment, the mounting wall (71) is provided with a second region (R2) around a first region (R1). The first region (R1) has less rigidity and superior fatigue characteristics than the second region (R2). Therefore, the first region (R1), which directly receives the load from the hydraulic cylinder (61), can efficiently absorb vibrations and shocks associated with vibrations, while reducing the possibility of damage due to fatigue.

[0075] Furthermore, in any of the first to third embodiments of the roller cover (70) according to the fourth embodiment of this disclosure, the first region (R1) is not provided with ribs to suppress deformation.

[0076] According to the roller cover (70) of this embodiment, since the first region (R1) is not provided with ribs to suppress deformation, the rigidity of the first region (R1) can be reduced compared to the case in which ribs are provided.

[0077] Furthermore, the crusher (10) according to the fifth aspect of this disclosure comprises a roller cover (70) as described in the second aspect and a housing (11) to which the roller cover (70) is attached, wherein the housing (11) has spring characteristics that absorb vibrations of frequencies exceeding the predetermined frequency.

[0078] According to the roller cover (70) of this embodiment, the housing (11) has spring characteristics that absorb vibrations at frequencies exceeding a predetermined frequency, so that the housing (11) can also absorb sudden vibrations and shocks associated with vibrations that are difficult to absorb by the accumulator (65).

[0079] Furthermore, a design method for a roller cover (70) according to a sixth aspect of this disclosure is a design method for a roller cover (70) that forms the outer wall of a crusher (10) for crushing solid fuel, wherein the roller cover (70) comprises a mounting wall (71) to which a hydraulic cylinder (61) that applies a crushing load to an arm portion (47) connected to a crushing roller (13) is connected at a mounting portion (72), and a first region (R1) is set in the mounting wall (71) in which the rigidity is substantially constant in the entire circumferential direction around the mounting portion (72).

[0080] Furthermore, a design method for a crusher (10) according to a seventh aspect of this disclosure is a design method for a crusher (10) for crushing solid fuel, wherein the crusher (10) comprises a hydraulic cylinder (61) that applies a crushing load to an arm portion (47) connected to a crushing roller (13), a roller cover (70) having a mounting wall (71) to which the hydraulic cylinder (61) is connected, a housing (11) to which the roller cover (70) is attached, and an accumulator (65) connected to the hydraulic cylinder (61) that absorbs vibrations of the hydraulic cylinder (61) below a predetermined frequency by suction and discharge of hydraulic fluid, and the mounting wall (71) is given a spring characteristic that absorbs vibrations at frequencies exceeding the predetermined frequency.

[0081] Furthermore, in the seventh embodiment, the design method for the crusher (10) according to the eighth aspect of this disclosure involves setting spring characteristics in the housing (11) that absorb vibrations at frequencies exceeding the predetermined frequency. [Explanation of Symbols]

[0082] 1. Power plant 10 Mills (Grinders) 11 Housing 11a opening 12 Grinding Tables 12a Swirling blade 12b Gas outlet for transport 13 Crushing rollers 14. Reducer (drive transmission unit) 15. Mill motor (drive unit) 16 Rotary classifier (classifying section) 16a blade 17 Coal feed pipe (fuel supply section) 18 Classification motor 19 Exit Ports 21. Bunker (storage area) 22 Downspout section 25 Coal feeding machine (fuel supply machine) 26 Conveying section 27. Coal feeder motor 30. Air blower unit (gas supply unit for transport) 30a Hot gas flow path 30b Cold gas flow path 30c thermal gas damper 30d Cold Gas Damper 31. Primary Air Fan (PAF) 32 Forced draft fan (FDF) 33. Induced Draft Fan (IDF) 34. Air preheater (heat exchanger) 40 State detection unit (temperature detection means, differential pressure detection means) 41 Bottom part 42 Ceiling section 45 Journal Heads 47 Support Arm 48 Support shaft 50 Control Unit 60 Load bearing device 61 Hydraulic Cylinder 61a Rod 62 Intermediate piston 63 Piston Housing 64 Flange 65 Accumulator 65a Oil port 70 Roller Cover 71 Mounting wall 72 Mounting part 80 Gap bolt 90 Lift Gauge 100 Solid Fuel Grinding Machine 110 Primary air passage (gas passage for transport) 120 Fine fuel supply channel (fine fuel supply pipe) 200 boilers 210 Furnace 220 burner (combustion device) R1 1st area R2 2nd area

Claims

1. A roller cover that forms the outer wall of a crusher for crushing solid fuel, The mounting wall is equipped with a hydraulic cylinder that applies a crushing load to an arm section connected to a crushing roller, and the mounting wall is connected to the arm section. The mounting wall is provided with a first region having substantially constant rigidity, extending around the entire circumference of the mounting portion. The hydraulic cylinder is connected to an accumulator that absorbs vibrations of the hydraulic cylinder below a predetermined frequency by drawing in and discharging hydraulic fluid. The mounting wall has spring properties that absorb vibrations of frequencies exceeding the predetermined frequency. Roller cover.

2. The mounting wall is provided with a second region around the first region. The first region has lower rigidity and superior fatigue characteristics compared to the second region. The roller cover according to claim 1.

3. The first region is not provided with ribs to suppress deformation. The roller cover according to claim 1.

4. The roller cover according to claim 1, The housing to which the roller cover is attached, Equipped with, The housing has spring characteristics that absorb vibrations at frequencies exceeding the predetermined frequency. Crusher.

5. A method for designing a roller cover that forms the outer wall of a crusher for crushing solid fuels, The roller cover includes a mounting wall to which a hydraulic cylinder that applies a crushing load to an arm portion connected to the crushing roller is connected at the mounting portion. The hydraulic cylinder is connected to an accumulator that absorbs vibrations of the hydraulic cylinder below a predetermined frequency by drawing in and discharging hydraulic fluid. The mounting wall is given spring characteristics that absorb vibrations of a frequency exceeding the predetermined frequency, A first region is set in the mounting wall body in which the rigidity is substantially constant throughout the entire circumference around the mounting portion. How to design a roller cover.

6. A method for designing a pulverizer for crushing solid fuels, The aforementioned crusher is A hydraulic cylinder that applies a crushing load to an arm connected to a crushing roller, A roller cover having a mounting wall to which the hydraulic cylinder is connected, The housing to which the roller cover is attached, An accumulator connected to the hydraulic cylinder absorbs vibrations of the hydraulic cylinder at a predetermined frequency or lower by suctioning and discharging hydraulic fluid, Equipped with, The mounting wall is configured to have spring characteristics that absorb vibrations of frequencies exceeding the predetermined frequency. How to design a crusher.

7. The housing is configured to have spring characteristics that absorb vibrations at frequencies exceeding the predetermined frequency. A method for designing a pulverizer according to claim 6.

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