Valve device, solid fuel pulverizing device, and method of operating valve device

Abstract

The purpose of the present invention is to enable simplification of repair work for a valve seat part. An outlet valve (60) is provided in a fuel supply pipe in which a solid-gas two-phase fluid (A1) flows, and is switchable between an open state in which the solid-gas two-phase fluid (A1) flows in the fuel supply pipe and a closed state in which the solid-gas two-phase fluid (A1) does not flow in the fuel supply pipe. The valve device (60) comprises: a body part (70) in which a flow path (62) through which the solid-gas two-phase fluid (A1) flows is formed; a valve body (80) which closes the flow path (62) in the closed state; and a valve seat part (90) including a base part (91) which is connected to the body part (70), and a ring-shaped member (92) which is fastened to the base part (91) by a bolt (93) and on which the valve body (80) abuts in the closed state.

Description

Valve device, solid fuel pulverizer, and valve device operating method

[0001] The present disclosure relates to a valve arrangement, a solid fuel comminution apparatus, and a method of operating the valve arrangement.

[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 is fed onto a pulverizing table and crushed between the pulverizing table and a pulverizing roller. The pulverized solid fuel is then separated into fine particles within a predetermined particle size range using a classifier. The fine particles are then discharged from the mill through an outlet valve using a carrier gas (primary air) supplied from the periphery of the pulverizing table. The pulverized fuel discharged from the mill is transported to a boiler and combusted in a combustion device. In a thermal power plant, the pulverized fuel is combusted in a boiler, where heat exchange with the combustion gas generates steam. This steam drives a steam turbine, which in turn drives a generator connected to the steam turbine, thereby generating electricity.

[0003] It is known that the outlet valve provided at the outlet of a mill is a three-way valve (for example, see Patent Document 1). Patent Document 1 describes a mill outlet valve connected to a discharge nozzle provided at the fine powder discharge port, a fine powder transport pipe, and a purge air supply pipe that supplies purge air to the fine powder transport pipe. In the device described in Patent Document 1, when the operation of the mill is stopped, purge air is supplied to the fine powder transport pipe by closing a first connection part connected to the fine powder discharge port.

[0004] JP 2015-147200 A

[0005] The valve seat used to close the first connection of the outlet valve described in Patent Document 1 is located in a portion through which pulverized fuel passes when the first connection is open. Because the valve seat of Patent Document 1 is exposed to the flow path of the pulverized fuel, it is prone to wear. If the valve seat wears, a gap may form between the valve body and the valve seat when closing the first connection, potentially preventing the first connection from being properly closed. Therefore, if the valve seat wears, it is necessary to remove the entire valve seat for repair. However, because the entire valve seat is a large component, repairing the valve seat can be cumbersome.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a valve device, a solid fuel pulverization device, and a method for operating the valve device that can simplify repair work on the valve seat portion.

[0007] In order to solve the above problems, the valve device, solid fuel pulverization device, and valve device operating method of the present disclosure employ the following means: A valve device according to one aspect of the present disclosure is a valve device that is provided in a pipe through which a solid-gas two-phase fluid flows, and is switchable between an open state in which the solid-gas two-phase fluid flows through the pipe and a closed state in which the solid-gas two-phase fluid does not flow through the pipe, and includes: a main body having a flow path through which the solid-gas two-phase fluid flows, a valve element that closes the flow path in the closed state, a base connected to the main body, and a valve seat having an abutment portion that is fastened to the base with a fastener and against which the valve element abuts in the closed state.

[0008] A method for operating a valve device according to one aspect of the present disclosure provides a valve device that is provided in a pipe through which a solid-gas two-phase fluid flows, and that can switch between an open state in which the solid-gas two-phase fluid flows through the pipe, and a closed state in which the solid-gas two-phase fluid does not flow through the pipe, the method comprising: a main body having a flow path formed therein through which the solid-gas two-phase fluid flows; a valve element that closes the flow path in the closed state; a base connected to the main body; and a valve seat having an abutment portion that is fastened to the base with a fastener and against which the valve element abuts in the closed state; and a closing step of abutting the valve element against the abutment portion to close the flow path.

[0009] According to the present disclosure, the repair work of the valve seat portion can be simplified.

[0010] Fig. 4 is a configuration diagram showing a solid fuel pulverization apparatus and a boiler according to an embodiment of the present disclosure; Fig. 5 is a longitudinal sectional view of an outlet valve according to an embodiment of the present disclosure, showing an open state; Fig. 6 is a longitudinal sectional view of an outlet valve according to an embodiment of the present disclosure, showing a closed state; Fig. 7 is an enlarged view of a main part (portion IV) of Fig. 3; Fig. 8 is a diagram showing a modified example of Fig. 4;

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a valve device, a solid fuel pulverization device, and a method of operating a valve device according to the present disclosure will be described below with reference to the drawings.

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. A power plant 1 according to this embodiment includes a solid fuel pulverizer 100 and a boiler 200. In the following description, "upper" refers to the vertically upper direction, and "upper" in terms such as upper part or upper surface refers to the vertically upper part. Similarly, "lower" refers to the vertically lower part, and the vertical direction is not precise and may include errors.

[0013] The solid fuel pulverizer 100 of this embodiment is an apparatus that pulverizes solid fuel such as biomass fuel or coal, generates pulverized fuel, and supplies it to the burner (combustion device) 220 of the boiler 200. The power plant 1 including the solid fuel pulverizer 100 and the boiler 200 shown in Fig. 1 is equipped with one solid fuel pulverizer 100, but may also be a system equipped with a plurality of solid fuel pulverizers 100 corresponding to the plurality of burners 220 of one boiler 200, respectively.

[0014] 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.

[0015] The mill 10, which pulverizes solid fuels such as coal and biomass fuels to be supplied to the boiler 200 into finely divided solid fuels, may be a mill that pulverizes only coal, only biomass fuel, or both coal and biomass fuel. Here, biomass fuel refers to renewable organic resources derived from 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 examples presented here. Biomass fuels are carbon-neutral because they absorb carbon dioxide during the biomass growth process and do not emit carbon dioxide, a greenhouse gas. Therefore, various uses of biomass fuels are being considered.

[0016] The mill 10 includes 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 rotating the grinding table 12, a rotary classifier (classifying unit) 16, a coal feed pipe (fuel supply unit) 17, and a classifier motor 18 that rotates the rotary classifier 16. The housing 11 is formed into a vertically extending cylindrical shape and is a housing that houses the grinding table 12, the grinding rollers 13, the rotary classifier 16, and the coal feed pipe 17. A coal feed pipe 17 is attached to the center of a ceiling portion 42 of the housing 11. The coal feed pipe 17 supplies solid fuel introduced from a bunker 21 via a coal feeder 25 into the housing 11. The coal feed pipe 17 is disposed vertically at the center of the housing 11, and its lower end extends into the interior of the housing 11.

[0017] A reducer 14 is installed near the bottom surface 41 of the housing 11, and the grinding table 12 is rotatably disposed, rotating by driving force transmitted from a mill motor 15 connected to the reducer 14. The grinding table 12 is a circular member in a plan view, and is disposed 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 curved upward. The coal feed pipe 17 supplies solid fuel (for example, coal or biomass fuel in this embodiment) from above toward the grinding table 12 below, and the grinding table 12 pinches the supplied solid fuel between the grinding rollers 13 and grinds it.

[0018] When solid fuel is fed from the coal feed pipe 17 toward the center of the grinding table 12, the centrifugal force generated by the rotation of the grinding table 12 guides the solid fuel toward the outer periphery of the grinding table 12, where it is pinched between the grinding table 12 and the grinding rollers 13 and pulverized. The pulverized solid fuel is blown upward by a carrier gas (hereinafter referred to as primary air) guided from a 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 is given a swirling force by the swirl blades, becoming an airflow with 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.

[0019] 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 to crush the solid fuel in cooperation with the crushing table 12. Although only one crushing roller 13 is shown in FIG. 1 as a representative example, 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, spaced apart by an angle of 120°. In this case, the portions of the three crushing rollers 13 that contact the upper surface of the crushing table 12 (pressing portions) are equidistant from the rotational axis of the crushing table 12.

[0020] 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 toward 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.

[0021] 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 move 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. Alternatively, the crushing load may be applied by the repulsive force of a spring (not shown).

[0022] 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.

[0023] The rotary classifier (classification unit) 16 is provided at the top of the housing 11 and has a hollow, inverted cone-shaped exterior. The rotary classifier 16 is provided with a plurality of blades 16a extending vertically 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 the pulverizing roller 13 (hereinafter, the pulverized solid fuel will be referred to as "pulverized fuel") into particles larger than a predetermined particle size (e.g., 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 "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 the coal feed pipe 17, centering on a cylindrical axis (not shown) extending in the vertical direction of the housing 11. Note that the classifier may be a fixed classifier equipped with a fixed hollow inverted cone-shaped casing and a plurality of fixed swirling vanes, instead of the blades 16a, at the outer periphery of the casing.

[0024] 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 fine pulverized fuel supply passage (solid fuel supply pipe) 120 and supplied to the burner 220 of the boiler 200.

[0025] The coal feed pipe 17 is attached so that its lower end extends vertically into the interior of the housing 11, penetrating the ceiling portion 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.

[0026] 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 inputs it into the interior. 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.

[0027] Normally, primary air is supplied to the inside of the mill 10 to transport pulverized fuel to the burner 220, and the pressure therein is higher than that of the coal feeder 25 and the bunker 21. The inside of the downspout 22, which connects the bunker 21 and the coal feeder 25, is layered with fuel. 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.

[0028] The blower unit 30 is a device that dries the pulverized fuel and blows primary air into the housing 11 to transport the air to the rotary classifier 16. In this embodiment, the blower unit 30 includes 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 to appropriately adjust the flow rate and temperature of the primary air blown into the housing 11.

[0029] In this embodiment, the hot gas flow path 30a supplies a portion of the air 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.

[0030] The cold gas flow path 30b supplies a portion of the air sent out from the primary air ventilator 31 as cold gas at room temperature. A cold gas damper 30d is provided 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.

[0031] In this embodiment, the flow rate of the primary air is the sum of the flow rate of the hot gas supplied from the hot gas flow path 30a and the flow rate of the cold gas supplied from the cold gas flow path 30b. 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 of the primary air blown into the housing 11 from the primary air flow path 110 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 flow path 30a and mixing it with the hot gas. By adjusting the oxygen concentration of the primary air, for example, when using a highly ignitable solid fuel, ignition of the solid fuel can be suppressed along the path from the mill 10 to the burner 220.

[0032] 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. That is, by adjusting the rotation speed of the rotary classifier 16 according to the pressure difference between the mill 10, the amount and particle size range of the pulverized fuel discharged from the outlet port 19 can be adjusted. Therefore, 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. The state detection unit 40 of this embodiment is, for example, a temperature measurement means, and 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 are not exceeded. Each upper limit temperature is determined taking into account the possibility of ignition depending on the properties of the solid fuel, etc. Furthermore, since the primary air is cooled by transporting the pulverized fuel while drying it inside the housing 11, the primary air temperature at the mill inlet is, for example, from room temperature to about 300 degrees, and the primary air temperature at the mill outlet is, for example, from room temperature to about 90 degrees.

[0033] The control unit 50 controls each component 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 pulverization table 12. The control unit 50 may, for example, transmit a drive command to the classifier motor 18 to control the rotation speed of the rotary classifier 16 to adjust classification performance, thereby stably supplying the pulverized fuel to the burner 220 in an amount 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. The control unit 50 may also, for example, transmit a drive command to the coal feeder motor 27 to adjust the amount of solid fuel supplied to the mill 10 (coal feed amount). The control unit 50 may also transmit an opening command to the blower unit 30 to control the openings of the hot gas damper 30c and the cold gas damper 30d to adjust the flow rate and temperature of the primary air. Specifically, the control unit 50 controls the opening of the hot gas damper 30c and the cold gas damper 30d so that the flow rate of the primary air supplied to the inside of the housing 11 and the temperature of the primary air at the outlet port 19 (mill outlet primary air temperature) become predetermined values ​​set in accordance with the coal feed amount for each type of solid fuel. Note that the control of the temperature of the primary air may be performed for the temperature at the mill inlet (mill inlet primary air temperature).

[0034] The control unit 50 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium, for example, in the form of a program. The CPU reads this program into the 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. The HDD may be replaced with a solid-state disk (SSD), for example.

[0035] 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.

[0036] 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 air (outside air) delivered 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.

[0037] 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), exchanges heat with primary air and secondary air in an air preheater 34, and 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 discharged from the primary air fan 31 is supplied to the hot gas flow path 30a. The water supplied to each heat exchanger of the boiler 200 is heated in an 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. The superheated steam is then sent to a steam turbine (not shown), which serves as a power generation unit, to drive the steam turbine, which in turn drives a generator (not shown) connected to the steam turbine to generate electricity, thereby constituting the power generation plant 1.

[0038] Next, the pulverized fuel supply pipe 120 and the outlet valve (valve device) 60 will be described in detail with reference to Figures 1 to 4. In the following description, an example will be described in which the outlet valve 60 is provided so that the upstream side of the gas-solid two-phase fluid A1, which is a mixture of the pulverized fuel and the primary air, is located at the bottom and the downstream side is located at the top, but the present disclosure is not limited to this. For example, the outlet valve may be provided so that the gas-solid two-phase fluid flows horizontally.

[0039] As shown in Figure 1, a plurality of outlet ports 19 are formed in a substantially circular ceiling portion 42 of the housing 11 of the mill 10. The outlet ports 19 are arranged in a row at predetermined intervals in the circumferential direction. A pulverized fuel supply pipe 120 is connected to each outlet port 19. A gas-solid two-phase fluid (hereinafter simply referred to as "gas-solid two-phase fluid A1") in which pulverized fuel and primary air are mixed flows through the pulverized fuel supply pipe 120.

[0040] Each pulverized fuel supply pipe 120 is provided with an outlet valve 60 (see FIGS. 2 and 3). The outlet valve 60 is provided at a midpoint of the pulverized fuel supply pipe 120. That is, the pulverized fuel supply pipe 120 has a pipe provided upstream of the outlet valve 60 (hereinafter referred to as "upstream pipe") and a pipe provided downstream of the outlet valve 60 (hereinafter referred to as "downstream pipe"). The outlet valve 60 may be directly connected to the outlet port 19.

[0041] The outlet valve 60 is a three-way valve connected to an upstream pipe, a downstream pipe, and a seal air supply pipe (seal gas supply pipe) 61 that supplies seal air (seal gas) A2 to the boiler 200 via the pulverized fuel supply pipe 120. The outlet valve 60 can switch between an open state in which a solid-gas two-phase fluid A1 flows through the pulverized fuel supply pipe 120 and a closed state in which the solid-gas two-phase fluid A1 does not flow through the pulverized fuel supply pipe 120. The outlet valve 60 can also switch between a state in which the seal air A2 supplied from the seal air supply pipe 61 is introduced into the interior (a flow path 62 described later) and a state in which the seal air A2 supplied from the seal air supply pipe 61 is not introduced into the interior (a flow path 62 described later).

[0042] 2 and 3, the seal air A2 flows through the seal air supply pipe 61. The seal air supply pipe 61 integrally includes a vertical section 61a extending vertically and a horizontal section 61b that bends from the downstream end of the vertical section 61a and extends horizontally. A seal air flow path (seal gas flow path) 61c through which the seal air A2 flows is formed inside the seal air supply pipe 61.

[0043] As shown in Figures 2 and 3, the outlet valve 60 includes a main body 70 connected to the upstream piping and the downstream piping, a valve element 80 provided inside the main body 70, and a valve seat 90 provided at the bottom of the main body 70.

[0044] The main body 70 is a cylindrical member centered on a central axis C, and has a flow path 62 formed therein through which the gas-solid two-phase fluid A1 and the seal air A2 flow. The main body 70 is made of a material with high abrasion resistance (e.g., spheroidal graphite cast iron, etc.). A wear-resistant portion 70b made of a material with better abrasion resistance than the main body 70 (e.g., ceramics, etc.) is provided at a portion of the main body 70 that comes into contact with the pulverized fuel. Specifically, the wear-resistant portion 70b is provided so as to cover substantially the entire inner circumferential surface of the main body 70.

[0045] The upper end (downstream end) of the main body 70 is connected to the downstream piping. The lower part (upstream part) of the main body 70 is connected to the valve seat 90. Hereinafter, the connection part between the main body 70 and the valve seat 90 will be referred to as the first connection part 71. Furthermore, the downstream end of the seal air supply pipe 61 is connected to the side of the main body 70. Hereinafter, the connection part between the main body 70 and the seal air supply pipe 61 will be referred to as the second connection part 72. The main body 70 has a bulging part 70a that bulges outward in the radial direction. The seal air supply pipe 61 is connected to the bulging part 70a. That is, the second connection part 72 is provided in the bulging part 70a.

[0046] The valve element 80 is configured to selectively close the first connection portion 71 and the second connection portion 72. In other words, the valve element 80 is configured to selectively close the flow path 62 and the seal air flow path 61c. The valve element 80 has a valve main body 81 and a valve support portion 82 that supports the valve main body 81.

[0047] The valve body 81 has a first closing portion 83 and a second closing portion 84. The first closing portion 83 closes the first connecting portion 71. The second closing portion 84 is provided on the valve body 81 on the opposite side from the first closing portion 83. The second closing portion 84 closes the second connecting portion 72. The first closing portion 83 is formed of a material with high wear resistance (e.g., spheroidal graphite cast iron, etc.). A wear-resistant portion 83a is provided on the surface of the first closing portion 83 and is formed of a material with better wear resistance than the first closing portion 83 (e.g., ceramics, etc.). The wear-resistant portion 83a is not provided at a position of the first closing portion 83 that abuts the valve seat portion 90.

[0048] One end of the valve support portion 82 is integrally connected to a drive shaft 85 provided in the bulge portion 70a. The other end of the valve support portion 82 is integrally connected to the valve body 81. The drive shaft 85 is rotatably driven by a drive source (not shown). When the drive shaft 85 is rotated, the valve support portion 82 rotates around the drive shaft 85. This causes the valve body 81 to move between a position where the first closing portion 83 closes the first connection portion 71 (the position shown in FIG. 3 ) and a position where the second closing portion 84 closes the second connection portion 72 (the position shown in FIG. 2 ). When the first closing portion 83 closes the first connection portion 71, the valve body 80 is pressed against the valve seat portion 90 by an air cylinder (not shown) or the like. The valve body 80 is fixed in the position where the first closing portion 83 closes the first connection portion 71 by a set bolt (not shown) or the like.

[0049] As shown in Figures 2 to 4, the valve seat portion 90 has a base portion 91 that is integrally formed with the main body portion 70, and a ring-shaped member (abutment portion) 92 that is fastened to the base portion 91 with a bolt (fastener) 93 and against which the valve body 80 abuts in the closed state (see Figure 3).

[0050] The base 91 is a cylindrical member centered on the central axis C, and has a flow path 62 formed therein through which the gas-solid two-phase fluid A1 flows. The base 91 is made of a material having high abrasion resistance (e.g., spheroidal graphite cast iron, etc.). A wear-resistant portion 91a made of a material having better abrasion resistance than the base 91 (e.g., ceramics, etc.) is provided at a portion of the base 91 that comes into contact with the pulverized fuel. Specifically, the wear-resistant portion 91a is provided so as to cover substantially the entire inner circumferential surface of the base 91.

[0051] The inner diameter of the base 91 is smaller than the inner diameter of the main body 70. Therefore, a step is formed at the connection (first connection portion 71) between the valve seat 90 and the main body 70 so that the lower portion protrudes radially inward. A ring-shaped member 92 is placed on the upper surface of this step (the upper surface of the base 91).

[0052] 4, the ring-shaped member 92 is an annular member. The ring-shaped member 92 is formed, for example, from a general structural rolled steel material (SS400 material) or the like. The ring-shaped member 92 is fixed to the base 91 by a plurality of bolts 93.

[0053] The ring-shaped member 92 integrally includes a fastening portion 92a through which the bolt 93 is inserted, and a protruding portion 92b that protrudes radially inward from the lower portion of the fastening portion 92a.

[0054] The fastening portion 92a is a cylindrical member, and its inner peripheral surface is connected to the outer peripheral surface of the protruding portion 92b. The fastening portion 92a abuts against the upper surface of the base portion 91 from above. The fastening portion 92a has a plurality of bolt insertion holes formed therein, which are arranged circumferentially at predetermined intervals. A bolt 93 is inserted into each bolt insertion hole. The bolts 93 are arranged so that their upper ends do not protrude from the bolt insertion holes.

[0055] The tip of the bolt 93 is inserted into a bolt insertion recess formed in the upper surface of the base 91. The tip of the bolt is threaded into the bolt insertion recess. In this manner, the bolt 93 fastens the ring-shaped member 92 to the base 91. The bolt 93 is arranged so as to be hidden by the valve seat 90 when viewed from the outlet port 19, which is upstream of the gas-solid two-phase fluid A1. This makes it possible to suppress wear on the bolt 93.

[0056] The protrusion 92b is a cylindrical member, the outer circumferential surface of which is connected to the inner circumferential surface of the fastening portion 92a. In the closed state, the outer circumferential surface of the first closing portion 83 of the valve body 80 comes into contact with the upper surface of the protrusion 92b. In this manner, the ring-shaped member 92 functions as a valve seat on which the first closing portion 83 of the valve body 80 sits. The protrusion 92b is provided so that its inner circumferential surface is flush with the inner circumferential surface of the wear-resistant portion 91a.

[0057] Next, the behavior of the outlet valve 60 will be described with reference to Figures 2 and 3. [Open State] For example, when the mill 10 is in normal operation (operation in which pulverized fuel pulverized by the mill 10 is combusted by the burner 220 to form a flame in the furnace 210 and steam is generated in the boiler 200), the outlet valve 60 is in an open state. As shown in Figure 2, when the second closing portion 84 of the valve body 80 closes the second connecting portion 72, the first connecting portion 71 of the outlet valve 60 is opened. That is, the outlet valve 60 is in an open state. When the outlet valve 60 is in the open state, a solid-gas two-phase fluid A1, which is a mixture of pulverized fuel generated by the mill 10 and primary air, flows through the outlet port 19, passes through the first connecting portion 71, and passes through the inside of the outlet valve 60. The solid-gas two-phase fluid A1 that has flowed through the inside of the outlet valve 60 is supplied to the boiler 200 (see Figure 1) via the pulverized fuel supply pipe 120 (see Figure 1). At this time, the seal air A2 is prevented from flowing by the second closing portion 84 and does not flow into the outlet valve 60 .

[0058] [Closed State] For example, when the operation of the mill 10 is stopped to perform maintenance, the outlet valve 60 is closed. That is, the outlet valve 60 is switched from an open state to a closed state. As shown in FIG. 3 , when the first closing portion 83 of the valve body 80 closes the first connection portion 71, the second connection portion 72 is opened. That is, the outlet valve 60 is closed. When the outlet valve 60 is closed, seal air A2 supplied from the seal air supply pipe 61 passes through the second connection portion 72 and flows inside the outlet valve 60. The seal air A2 that has flowed inside the outlet valve 60 is supplied to the boiler 200 (see FIG. 1) via the pulverized fuel supply pipe 120 (see FIG. 1). More specifically, the seal air A2 is supplied to the burner 220 of the boiler 200 and cools the burner 220. At this time, the interior space of the mill 10 and the interior of the outlet valve 60 are isolated by the first closing portion 83. That is, the internal space of the mill 10 and the internal space of the furnace 210 are isolated from each other.

[0059] As shown in Figure 4, in the closed state, the lower surface of the outer periphery of the first closing portion 83 is in surface contact with the upper surface of the ring-shaped member 92 (more specifically, the protrusion 92b). At this time, the first closing portion 83 and the ring-shaped member 92 are in direct contact without an abrasion-resistant portion or the like interposed therebetween. This direct contact without an abrasion-resistant portion or the like interposed therebetween can improve sealing performance. Note that the portion of the lower surface of the first closing portion 83 that contacts the ring-shaped member 92 of the valve seat portion 90 may be recessed upward relative to the other portions.

[0060] The present embodiment provides the following advantageous effects. The valve seat 90 may be worn by, for example, the gas-solid two-phase fluid A1 flowing through the flow path. If the portion of the valve seat 90 that abuts against the valve element 80 becomes worn, a gap will be formed between the valve element 80 and the valve seat 90 when the flow path is closed (i.e., when the valve element 80 and the valve seat 90 are in abutting contact). This may result in the inability to suitably block the gas-solid two-phase fluid A1 even in the closed state. In consideration of this, when the valve seat 90 becomes worn, it has been necessary to repair the valve seat 90.

[0061] In this embodiment, the valve seat portion 90 has a ring-shaped member 92 that is fastened to a base portion 91 with bolts 93. As a result, if the ring-shaped member 92 that abuts against the valve body 80 becomes worn, the bolts 93 can be released to remove the ring-shaped member 92 from the base portion 91, and only the ring-shaped member 92 can be replaced. This simplifies the repair work for the valve seat portion 90 compared to replacing the entire valve seat portion 90. This shortens the time required for the repair work, thereby reducing maintenance costs.

[0062] Furthermore, since only the ring-shaped member 92 needs to be replaced, rather than the entire valve seat 90, fewer or smaller parts need to be replaced compared to replacing the entire valve seat 90. This reduces the cost required for repairs.

[0063] Furthermore, in this embodiment, the base 91 and the ring-shaped member 92 are separate bodies. Therefore, the base 91 and the ring-shaped member 92 can be manufactured separately. This allows each component constituting the valve seat 90 to be manufactured more compact and easier to handle than when the base 91 and the ring-shaped member 92 are integral. This improves the machining accuracy of each component constituting the valve seat 90. Because the machining accuracy of the ring-shaped member 92 can be improved, the valve element 80 and the ring-shaped member 92 can be more appropriately abutted against each other, improving the sealing performance between the valve element 80 and the ring-shaped member 92. This improves the performance of the outlet valve 60.

[0064] Furthermore, for example, if the ring-shaped member 92 is fitted to the base 91, it is difficult to remove the ring-shaped member 92 from the base 91. This can complicate the work of removing the ring-shaped member 92, such as by removing the valve seat portion 90 itself from the outlet valve 60 in order to remove the base 91 from the ring-shaped member 92. On the other hand, in this embodiment, the ring-shaped member 92 is fastened to the base 91 by the bolts 93. This allows the ring-shaped member 92 to be removed from the base 91 simply by releasing the fastening of the bolts 93. Therefore, the ring-shaped member 92 can be easily removed. This simplifies the repair work of the valve seat portion 90.

[0065] In this embodiment, the ring-shaped member 92 is detachably attached to the base 91. This allows the ring-shaped member 92 to be easily removed, thereby simplifying the repair work of the valve seat portion 90.

[0066] Furthermore, even if the outlet valve 60 is a so-called three-way valve that also has the function of directing the seal gas into the main body, it is possible to replace only the ring-shaped member 92. Therefore, even in a three-way valve, the repair work of the valve seat 90 can be simplified.

[0067] In this embodiment, the position of the valve element 80 in the open state is located downstream in the flow direction of the solid-gas two-phase fluid A1 relative to the position in the closed state. This allows the seal air A2 flowing into the seal air flow path from the seal air supply pipe 61 to press the valve element 80 against the valve seat 90 in the closed state. Therefore, the flow path can be more suitably closed in the closed state. That is, in the closed state, the valve element 80 is pressed against the valve seat 90 by an air cylinder (not shown), a set bolt (not shown), or the like, but this pressing is supported by the seal air A2. Therefore, the flow path can be more suitably closed in the closed state.

[0068] [Modification] Next, a modification of this embodiment will be described with reference to Figure 5. This modification differs from the above embodiment in that a wear-resistant member is provided on the ring-shaped member 92. Since the other points are the same as those of the above embodiment, the same components are denoted by the same reference numerals and detailed descriptions thereof will be omitted.

[0069] As shown in FIG. 5 , the ring-shaped member 92 according to this modification has a wear-resistant portion on the surface exposed to the flow path 62. Specifically, a wear-resistant portion 92ba is provided on the inner circumferential surface of the protruding portion 92b. A wear-resistant portion 92aa is also provided on the inner circumferential surface of the fastening portion 92a (specifically, the inner circumferential surface of the portion of the fastening portion 92a that protrudes above the protruding portion 92b). The wear-resistant portion 92aa and the wear-resistant portion 92ba are formed of a material (e.g., ceramics) that has better wear resistance than the ring-shaped member 92. No wear-resistant portion is provided on the upper surfaces of the protruding portion 92b and the fastening portion 92a. The inner circumferential surface of the wear-resistant portion 92ba is flush with the inner circumferential surface of the wear-resistant portion 91a.

[0070] This modification provides the following advantageous effects: In this modification, the ring-shaped member 92 is provided with the wear-resistant portions 92aa and 92ba on the surface exposed to the flow path 62. This reduces wear on the ring-shaped member 92. This extends the life of the ring-shaped member 92.

[0071] The present disclosure is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the present disclosure. For example, the solid fuel used is not limited to the present disclosure, and coal, biomass fuel, petroleum coke (PC), etc. can be used. Furthermore, these solid fuels may be used in combination.

[0072] Furthermore, the method for manufacturing the valve device according to the present disclosure is not particularly limited. The valve device according to the present disclosure may be newly manufactured, or the valve device according to the present disclosure may be manufactured by adding a ring-shaped member to an existing valve body that does not have a ring-shaped member.

[0073] In the above embodiment, an example in which the valve device according to the present disclosure is provided in the pulverized fuel supply pipe 120 has been described, but the present disclosure is not limited to this. The valve device according to the present disclosure can be applied to other piping as long as it is a piping through which a solid-gas two-phase fluid flows.

[0074] The valve device, solid fuel pulverization device, and method of operating the valve device described in the above-described embodiments can be understood, for example, as follows: A valve device according to a first aspect of the present disclosure is a valve device that is provided in a pipe through which a solid-gas two-phase fluid flows, and is switchable between an open state in which the solid-gas two-phase fluid flows through the pipe, and a closed state in which the solid-gas two-phase fluid does not flow through the pipe, and includes: a main body having a flow path through which the solid-gas two-phase fluid flows, a valve element that closes the flow path in the closed state, a base connected to the main body, and a valve seat having an abutment portion that is fastened to the base with a fastener and against which the valve element abuts in the closed state.

[0075] The valve seat may be worn by, for example, a gas-solid two-phase fluid flowing through the flow path. If the portion of the valve seat that contacts the valve disc (hereinafter referred to as the "contact portion") becomes worn, a gap forms between the valve disc and the contact portion when the flow path is closed (i.e., when the valve disc and the contact portion are in contact). This can result in the valve being unable to properly block the gas-solid two-phase fluid even in the closed state. Considering this, it has been necessary to repair the valve disc when the contact portion becomes worn. In the above configuration, the valve seat has an abutment portion that is fastened to the base with a fastener. As a result, if the abutment portion becomes worn, the fastener can be released, the abutment portion can be removed from the base, and only the abutment portion can be replaced. This simplifies the valve seat repair process compared to replacing the entire valve seat. This shortens the repair time, thereby reducing maintenance costs.

[0076] Furthermore, since only the contact portion needs to be replaced, rather than the entire valve seat, fewer or smaller parts need to be replaced compared to replacing the entire valve seat, thereby reducing repair costs.

[0077] Furthermore, in the above configuration, the base and the abutment portion are separate bodies. Therefore, the base and the abutment portion can be manufactured separately. This allows each component constituting the valve seat to be manufactured more compact and easier to handle than when the base and the abutment portion are integrated. This improves the machining accuracy of each component constituting the valve seat. Because the machining accuracy of the abutment portion can be improved, the valve body and the abutment portion can be more appropriately abutted against each other, improving the sealing performance between the valve body and the abutment portion. This improves the performance of the valve device.

[0078] Furthermore, for example, when the abutment portion is fitted to the base, it is difficult to remove the abutment portion from the base. This can complicate the process of removing the abutment portion, such as by removing the valve seat portion itself from the valve device in order to remove the base from the abutment portion. On the other hand, in the above configuration, the abutment portion is fastened to the base by a fastener. This allows the abutment portion to be removed from the base simply by releasing the fastener. Therefore, the abutment portion can be easily removed. This simplifies the repair process for the valve seat portion.

[0079] A valve device according to a second aspect of the present disclosure is the valve device of the first aspect, wherein the abutment portion is detachably attached to the base portion.

[0080] In the above-described configuration, the abutment portion is detachably attached to the base portion, which allows the abutment portion to be easily removed, thereby simplifying the repair work of the valve seat portion.

[0081] A valve device according to a third aspect of the present disclosure is, in the first or second aspect described above, a sealing gas flow path through which a sealing gas flows is formed in the main body portion, and a sealing gas supply pipe is connected to supply the sealing gas to the flow path, and the valve body closes the sealing gas flow path in the open state and opens the sealing gas flow path in the closed state.

[0082] In the above configuration, a seal gas flow path is formed inside through which the seal gas flows, and a seal gas inlet pipe is connected to the main body and introduces the seal gas into the seal gas flow path. Thus, even if the valve device is a so-called three-way valve that also has the function of introducing the seal gas into the main body, only the contact part can be replaced. Therefore, repair work on the valve seat can be simplified even in three-way valves.

[0083] A valve device according to a fourth aspect of the present disclosure is the valve device of the third aspect, wherein the valve element in the open state is located downstream in the flow direction of the solid-gas two-phase fluid from the position in the closed state, and the main body is connected to the sealing gas supply pipe downstream from the position of the valve element in the closed state.

[0084] In the above configuration, the valve element is located downstream in the flow direction of the gas-solid two-phase fluid in the open state relative to the valve element in the closed state. This allows the seal gas flowing into the seal gas flow passage from the seal gas inlet pipe to press the valve element against the valve seat in the closed state. This allows the flow passage to be closed more effectively in the closed state.

[0085] A valve device according to a fifth aspect of the present disclosure is the valve device of any one of the first to fourth aspects, wherein a wear-resistant portion is provided on a surface of the abutting portion that is exposed to the flow path.

[0086] In the above configuration, a wear-resistant material is provided on the exposed surface of the contact portion, which makes it possible to suppress wear of the contact portion and therefore to extend the life of the contact portion.

[0087] The solid fuel pulverization apparatus according to the first aspect of the present disclosure comprises a pulverization section that pulverizes solid fuel, a solid fuel supply pipe that guides the solid fuel pulverized in the pulverization section to a boiler together with a carrier gas, and a valve device according to any one of the first to fifth aspects that is provided on the solid fuel supply pipe, wherein the piping has the solid fuel supply pipe, and the solid-gas two-phase fluid has a solid-gas two-phase fluid of pulverized solid fuel and a carrier gas.

[0088] A method for operating a valve device according to a first aspect of the present disclosure provides a valve device that is provided in a pipe through which a solid-gas two-phase fluid flows, and that can switch between an open state in which the solid-gas two-phase fluid flows through the pipe, and a closed state in which the solid-gas two-phase fluid does not flow through the pipe, the method comprising: a main body having a flow path formed therein through which the solid-gas two-phase fluid flows; a valve element that closes the flow path in the closed state; a base connected to the main body; and a valve seat having an abutment portion that is fastened to the base with a fastener and against which the valve element abuts in the closed state; and a closing step of abutting the valve element against the abutment portion to close the flow path.

[0089] 1: Power generation plant 10: Mill 11: Housing 12: Grinding table 13: Grinding roller 14: Reducer 15: Mill motor 16: Rotary classifier 16a: Blade 17: Coal feed pipe 18: Classifier motor 19: Outlet port 21: Bunker 22: Downspout section 25: Coal feeder 26: Conveying section 27: Coal feeder motor 30: Blower section 30a: Hot gas flow path 30b: Cold gas flow path 30c: Hot gas damper 30d: Cold gas damper 31: Primary air ventilator 34: Air preheater 40: Status detection section 41: Bottom section 42: Ceiling section 45: Journal head 46: Pressing device 47: Support arm 48: Support shaft DESCRIPTION OF SYMBOLS 50: Control unit 60: Outlet valve (valve device) 61: Seal air supply pipe (seal gas supply pipe) 61a: Vertical portion 61b: Horizontal portion 61c: Seal air flow path (seal gas flow path) 62: Flow path 70: Main body 70a: Bulging portion 70b: Wear-resistant portion 71: First connecting portion 72: Second connecting portion 80: Valve body 81: Valve body 82: Valve support portion 83: First closing portion 83a: Wear-resistant portion 84: Second closing portion 85: Drive shaft 90: Valve seat portion 91: Base portion 91a: Wear-resistant portion 92: Ring-shaped member (contact portion) 92a: Fastening portion 92aa: Wear-resistant portion 92b: Protruding portion 92ba: Wear-resistant portion 93 : Bolt (fastener) 100: Solid fuel pulverizer 110: Primary air flow path 120: Pulverized fuel supply pipe 200: Boiler 210: Furnace 220: Burner A1: Solid-gas two-phase fluid A2: Seal air (seal gas) C: Central axis

Claims

1. A valve device that is installed in a pipe through which a solid-gas two-phase fluid flows, and that can switch between an open state in which the solid-gas two-phase fluid flows through the pipe, and a closed state in which the solid-gas two-phase fluid does not flow through the pipe, the valve device comprising: a main body portion in which a flow path through which the solid-gas two-phase fluid flows is formed; a valve element that closes the flow path in the closed state; a base portion connected to the main body portion; and a valve seat portion that has an abutment portion that is fastened to the base with a fastener and against which the valve element abuts in the closed state.

2. The valve device according to claim 1, wherein the abutment portion is detachably attached to the base portion.

3. A valve device as described in claim 1, wherein the main body has a seal gas flow path formed therein through which a seal gas flows, and a seal gas supply pipe is connected to supply the seal gas to the flow path, and the valve body closes the seal gas flow path in the open state and opens the seal gas flow path in the closed state.

4. A valve device as described in claim 3, wherein the valve element in the open state is located downstream in the flow direction of the solid-gas two-phase fluid from the position in the closed state, and the main body is connected to the seal gas supply pipe downstream from the position of the valve element in the closed state.

5. The valve device according to claim 1, wherein a wear-resistant portion is provided on the surface of the contact portion exposed to the flow path.

6. A solid fuel pulverization device comprising: a pulverization section for pulverizing solid fuel; a solid fuel supply pipe for conducting the solid fuel pulverized in the pulverization section together with a carrier gas to a boiler; and a valve device as described in any one of claims 1 to 5 provided on the solid fuel supply pipe, wherein the piping has the solid fuel supply pipe, and the solid-gas two-phase fluid has a solid-gas two-phase fluid of pulverized solid fuel and a carrier gas.

7. A valve device that is provided in a pipe through which a solid-gas two-phase fluid flows, and that can switch between an open state in which the solid-gas two-phase fluid flows through the pipe, and a closed state in which the solid-gas two-phase fluid does not flow through the pipe, comprising: a main body portion in which a flow path through which the solid-gas two-phase fluid flows is formed; a valve element that closes the flow path in the closed state; a base portion connected to the main body portion; and a valve seat portion having an abutment portion that is fastened to the base with a fastener and against which the valve element abuts in the closed state, and a closing step of abutting the valve element against the abutment portion to close the flow path.

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