JP7475876B2 - Emission device, solid fuel pulverizer, boiler system, and method for operating the emission device - Google Patents

Description

The present disclosure relates to an exhaust device, a solid fuel pulverizer, a boiler system, and a method for operating the exhaust device.

Conventionally, in thermal power plants, solid fuels (carbon-containing solid fuels) such as coal and biomass fuels are pulverized into fine powder within a specified particle size range in a pulverizer (mill) and then supplied to a combustion device. The mill pulverizes solid fuels such as coal and biomass fuels fed onto a rotating table by crushing them between the rotating table and rollers, and the pulverized fuel is sorted into fine particles within a specified particle size range using a classifier by a conveying gas supplied from the outer periphery of the rotating table, and then transported to a boiler and burned in a combustion device. In thermal power plants, steam is generated by heat exchange with the combustion gas generated by combustion in the boiler, and the steam is used to rotate and drive a steam turbine, which then rotates and drives a generator connected to the steam turbine, generating electricity.

When the pulverizer is stopped, it is necessary to discharge the pulverized solid fuel (for example, in the case of coal, it is also called residual charcoal) remaining inside the pulverizer housing in order to prevent the solid fuel inside the housing from igniting when the pulverizer is restarted. During normal shutdown, the turntable is rotated while supplying carrier gas for a certain period of time after coal supply is stopped, and a purging operation is performed to discharge the solid fuel remaining inside the housing to the combustion device. On the other hand, when the pulverizer is stopped in an emergency due to a problem, etc., it is necessary to discharge the residual charcoal from the housing by a clearing operation, etc. The clearing operation is an operation in which the turntable is rotated without supplying carrier gas, the residual charcoal on the turntable is dropped to the bottom plate (bottom part) of the housing by centrifugal force, and the solid fuel that has fallen and accumulated on the bottom part is guided to an opening formed in the bottom part by a scraper that rotates and moves on the bottom part of the housing, and is discharged from this opening to a spillage hopper via a spillage chute.

The spillage chute must reliably discharge solid fuels, etc. into the spillage hopper. For this reason, pulverizers that have air nozzles in the spillage chute to prevent the solid fuels, etc. from clogging the spillage chute are known (see, for example, Patent Document 1). Patent Document 1 describes a pulverizer that has an air nozzle inside the spillage chute.

Japanese Utility Model Application Publication No. 4-26035

In the event of an emergency shutdown of the pulverizer, inert steam may be injected into the mill to prevent the pulverized solid fuel remaining inside the pulverizer housing from heating up due to natural oxidation. Due to the moisture in the injected inert steam and the moisture originally contained in the solid fuel, the solid fuel may be in a state where it is likely to adhere to the wall when it is discharged from the opening at the bottom of the pulverizer to the spillage hopper through the spillage chute. For this reason, the solid fuel that flows into the spillage chute may adhere or accumulate on the inner surface of the spillage chute, causing the spillage chute to become clogged. If the spillage chute becomes clogged and solid fuel cannot be discharged properly, this may cause problems when the pulverizer is restarted, and a new process is required to resolve the blockage.

In the pulverizer of Patent Document 1, an air nozzle is provided in an area vertically below the foreign matter discharge port (opening formed in the bottom surface) in the lower table chamber of the housing in order to prevent the solid fuel from clogging the spillage chute. As a result, foreign matter and solid fuel that flow into the spillage chute from the opening are expelled from the air nozzle, eliminating clogging of the spillage chute, and facilitating discharge, but some of the solid fuel falls to the top of the air nozzle. As a result, there is a possibility that the solid fuel that falls onto the air nozzle will accumulate on the air nozzle. When solid fuel accumulates on the air nozzle, the accumulated solid fuel will become a starting point and a pile of solid fuel will become larger, and the solid fuel may cause the spillage chute to become clogged.

The present disclosure has been made in consideration of these circumstances, and aims to provide an exhaust device, a solid fuel pulverizer, a boiler system, and an operating method for the exhaust device that can suppress clogging of the exhaust device.

In order to solve the above problems, the discharge device, solid fuel pulverizer, boiler system, and discharge device operating method of the present disclosure employ the following means.
An exhaust device according to one embodiment of the present disclosure is an exhaust device that exhausts pulverized solid fuel from an opening provided in a housing that forms the outer shell of a crusher that pulverizes solid fuel, and is equipped with a duct that is provided below the opening, communicates with the opening, and through which the pulverized solid fuel exhausted from the opening flows, and an injection unit that is provided inside the duct and injects a fluid into the inside of the duct, and the injection unit is provided below the opening and outside the opening when the opening is viewed in a plane.

An operating method of an exhaust device according to one aspect of the present disclosure is a method of operating an exhaust device that exhausts pulverized solid fuel from an opening provided in a housing that forms the outer shell of a pulverizer that pulverizes solid fuel, the exhaust device having a duct provided below the opening, communicating with the opening, through which the pulverized solid fuel discharged from the opening flows, and an injection unit provided inside the duct and outside the opening when the opening is viewed from above, which injects a fluid into the duct, and includes an injection step of injecting the fluid from the injection unit.

This disclosure makes it possible to prevent clogging of the discharge device.

1 is a schematic configuration diagram of a boiler system according to an embodiment of the present disclosure. FIG. FIG. 2 is a schematic vertical cross-sectional view of the solid fuel pulverizer of FIG. 1. FIG. 3 is a schematic vertical cross-sectional view showing a discharge device of the solid fuel pulverizer of FIG. 2 . 3 is a schematic plan view showing an opening and an assist gas ejection portion formed in the solid fuel pulverization apparatus of FIG. 2. FIG. 4B is a side view of the flange joint of FIG. 4A. FIG. 3 is a schematic vertical cross-sectional view of the discharge device of the solid fuel pulverizer of FIG. 2, showing the relationship between the position at the opening and the discharge amount of residual carbon. FIG. 2 is a schematic diagram showing a supply pipe of the discharge device of the present disclosure. 6B is a graph showing the relationship between the injection amount of assist gas of the exhaust device of FIG. 6A and the mill load. FIG. 6B is a diagram showing a modification of FIG. 6A. 7B is a graph showing the relationship between the injection amount of assist gas of the exhaust device of FIG. 7A and the mill load. FIG. 6B is a schematic diagram showing the supply piping of the discharge device of the present disclosure, illustrating a modification of FIG. 6A. 8B is a graph showing the relationship between the injection amount of assist gas of the exhaust device of FIG. 8A and the mill load. FIG. 4 is a schematic vertical sectional view showing a modified example of FIG. 3 . FIG. 4 is a schematic vertical sectional view showing a modified example of FIG. 3 . FIG. 4 is a schematic vertical sectional view showing a modified example of FIG. 3 .

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
The boiler system 1 according to this embodiment includes a solid fuel pulverizer 100 and a boiler 200 .

As shown in FIG. 1, the solid fuel pulverizer 100 of this embodiment is an apparatus that pulverizes solid fuel (carbon-containing solid fuel) such as coal or biomass fuel, generates pulverized fuel, and supplies it to the burner section (combustion device) 220 of the boiler 200. The boiler system 1 including the solid fuel pulverizer 100 and the boiler 200 shown in FIG. 1 includes one solid fuel pulverizer 100, but the system may include multiple solid fuel pulverizers 100 corresponding to the multiple burner sections 220 of one boiler 200.

The solid fuel pulverizing device 100 of this embodiment includes a mill (pulverizer) 10 , a coal feeder 20 , a blower section 30 , a state detector 40 , a controller 50 , and a discharge device 60 .
In this embodiment, "upper" refers to the vertically upper direction, and "upper" in the terms "upper" and "upper surface" refers to the vertically upper part. Similarly, "lower" refers to the vertically lower part, and the vertical direction is not precise and may include errors.

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

As shown in Figures 1 and 2, the mill 10 includes a housing (casing) 11 forming an outer shell, a rotating table 12, rollers 13, a drive unit 14, a rotary classifier 16, a fuel supply unit 17, a motor 18 that drives and rotates the rotary classifier 16, and a scraper 70 that removes deposits accumulated on the bottom portion 11d of the housing 11.
The housing 11 is formed in a cylindrical shape extending in the vertical direction, and is a case that houses the rotary table 12, the rollers 13, the rotary classifier 16, and the fuel supply unit 17. The inner peripheral surface 11a of the housing 11 is substantially cylindrical, and a central axis C1 (see FIG. 2) extending in the vertical direction of the housing 11 substantially coincides with the central axis C1 of the rotary table 12 and the rotary classifier 16 described below.
A fuel supply unit 17 is attached to the center of the ceiling portion 42 of the housing 11. This fuel supply unit 17 supplies solid fuel guided from the bunker 21 into the housing 11, and is disposed in the vertical direction at the center position of the housing 11 with its lower end extending into the interior of the housing 11.

A drive unit 14 is provided near the bottom surface 41 of the housing 11, and a rotary table 12 that rotates by a driving force transmitted from the drive unit 14 is disposed so as to be freely rotatable.
The turntable 12 is a member having a circular shape in a plan view, and is disposed so as to face the lower end of the fuel supply unit 17. The upper surface of the turntable 12 may have an inclined shape, for example, such that the center is low and the outer periphery is high, and the outer periphery is bent upward. The fuel supply unit 17 supplies solid fuel (for example, coal or biomass fuel in this embodiment) from above toward the turntable 12 below, and the turntable 12 crushes the supplied solid fuel between the rollers 13 and is also called a crushing table.

When solid fuel is fed from the fuel supply unit 17 toward the approximate center region of the turntable 12, the centrifugal force generated by the rotation of the turntable 12 guides the solid fuel toward the outer periphery of the turntable 12, where it is pinched between the 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) 100a, and is guided to the rotary classifier 16. The primary air flow path 100a supplies primary air into the housing 11 via a primary air duct (carrier gas supply duct) 27 (see FIG. 2) connected to the housing 11 below the turntable 12.
An outlet 25 (see FIG. 2) is provided on the outer periphery of the rotary table 12, through which the primary air flowing in from the primary air passage 100a through the primary air duct 27 flows out into the space above the rotary table 12 in the housing 11. A vane 26 (see FIG. 2) is provided near the outlet 25, which applies a swirling force to the primary air blown out from the outlet 25. The primary air given a swirling force by the vane 26 becomes an airflow having a swirling velocity component, and guides the solid fuel pulverized on the rotary table 12 to the rotary classifier 16 located above in the housing 11. Among the pulverized solid fuel particles mixed with the primary air, those larger than a predetermined particle size are classified by the rotary classifier 16, or fall back to the rotary table 12 without reaching the rotary classifier 16, and are pulverized again between the rollers 13.

The rollers 13 are rotating bodies that pulverize the solid fuel supplied from the fuel supply unit 17 to the turntable 12. The rollers 13 are pressed against the upper surface of the turntable 12 and cooperate with the turntable 12 to pulverize the solid fuel.
1 shows only one representative roller 13, multiple rollers 13 are arranged facing each other at regular intervals in the circumferential direction so as to press against the upper surface of the turntable 12. For example, three rollers 13 are arranged at equal intervals in the circumferential direction on the outer periphery at angular intervals of 120°. In this case, the portions where the three rollers 13 come into contact with the upper surface of the turntable 12 (pressing portions) are equidistant from the central axis of rotation (central axis C1) of the turntable 12.

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

The support arm 47 of the journal head 45 is supported on the side portion 11b of the housing 11 by a support shaft 48 whose middle portion is aligned horizontally so that it can swing around the support shaft 48 in the vertical direction of the roller 13. In addition, a pressing device 49 is provided on the upper end portion on the vertically upper side of the support arm 47. The pressing device 49 is fixed to the housing 11 and applies a load to the roller 13 via the support arm 47 etc. so as to press the roller 13 against the rotating table 12.

The drive unit 14 is a device that transmits a driving force to the turntable 12 and rotates the turntable 12 around the central axis C1. The drive unit 14 generates a driving force that rotates the turntable 12.

The rotary classifier 16 is provided at the top of the housing 11 and has a hollow, approximately inverted cone-shaped exterior. The rotary classifier 16 is provided with a number of blades 16a extending in the vertical direction at its outer periphery. Each blade 16a is provided at a predetermined interval (equally spaced) around the central axis C1 of the rotary classifier 16. The rotary classifier 16 is a device that classifies the solid fuel pulverized by the roller 13 into particles larger than a predetermined particle size (for example, 70 to 100 μm for coal) (hereinafter, pulverized solid fuel exceeding the predetermined particle size will be referred to as "coarse pulverized fuel") and particles smaller than the predetermined particle size (hereinafter, pulverized solid fuel smaller than the predetermined particle size will be referred to as "fine pulverized fuel"). The rotary classifier 16, which classifies by rotation, is also called a rotary separator, and is given a rotational driving force by a motor 18 controlled by the control unit 50, and rotates around the fuel supply unit 17 around a cylindrical axis (not shown) extending in the vertical direction of the housing 11.

When the pulverized solid 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 rotary table 12 to be pulverized again, and the fine pulverized fuel is led to the outlet 19 in the ceiling 42 of the housing 11.
The pulverized fuel classified by the rotary classifier 16 is discharged from the outlet 19 to the supply passage 100b and is transported to a subsequent process together with the primary air. The pulverized fuel flowing out to the supply passage 100b is supplied to the burner unit 220 of the boiler 200.

The fuel supply unit 17 is attached so that its lower end extends vertically into the interior of the housing 11 so as to penetrate the upper end of the housing 11, and supplies solid fuel fed from the top of the fuel supply unit 17 to the approximate central region of the turntable 12. The fuel supply unit 17 is supplied with solid fuel from the coal feeder 20.

The coal feeder 20 includes a conveying unit 22 and a motor 23. The conveying unit 22 conveys the solid fuel discharged from the lower end of the downspout unit 24 located immediately below the bunker 21 by the driving force provided by the motor 23, and guides the solid fuel to the fuel supply unit 17 of the mill 10.
Normally, primary air is supplied to the inside of the mill 10 to transport the pulverized fuel, which is the pulverized solid fuel, and the pressure inside the mill 10 is high. The downspout 24, which is a pipe extending in the vertical direction directly below the bunker 21, holds fuel in a layered state inside the downspout 24, and the solid fuel layers stacked inside the downspout 24 ensure a seal that prevents the primary air on the mill 10 side and the pulverized fuel from flowing back in.
The amount of solid fuel supplied to the mill 10 (the amount of coal fed) may be adjusted by the belt speed of the belt conveyor of the transport section 22 .

The blower section 30 is a device that blows primary air (also referred to as "conveying air" in the following description) into the inside of the housing 11 to dry the solid fuel pulverized by the roller 13 and supply it to the rotary classifier 16.
In order to adjust the primary air blown into the housing 11 to an appropriate temperature, in this embodiment, the blower section 30 is equipped with a primary air fan (PAF) 31, a hot gas flow path 30a, a cold gas flow path 30b, a hot gas damper 30c, and a cold gas damper 30d.

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

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 (second blower) 30d is provided downstream of the cold gas flow path 30b. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The flow rate of cold gas supplied from the cold gas flow path 30b is determined by the opening degree of the cold gas damper 30d.

In this embodiment, the flow rate of the primary air is the sum of the flow rate of the hot gas supplied from the hot gas flow path 30a and the flow rate of the cold gas supplied from the cold gas flow path 30b, and is controlled by the control unit 50 in accordance with the supply amount (coal feed amount) of solid fuel supplied to the mill 10. The temperature of the primary air is determined by the mixing ratio of the hot gas supplied from the hot gas flow path 30a and the cold gas supplied from the cold gas flow path 30b, and is controlled by the control unit 50.
In addition, the oxygen concentration of the primary air flowing in from the primary air flow path 100a may be adjusted by introducing a portion of the combustion gas discharged from the boiler 200 via a gas recirculation fan (not shown) into the hot gas supplied from the hot gas flow path 30a to form an air-fuel mixture.

In this embodiment, the state detection unit 40 of the mill 10 transmits measured or detected data to the control unit 50. The state detection unit 40 of this embodiment is, for example, a differential pressure measurement means, and measures the differential pressure between the portion where the primary air flows into the inside of the mill 10 from the primary air flow path 100a and the outlet 19 where the primary air and the pulverized fuel are discharged from the inside of the mill 10 to the supply flow path 100b as the differential pressure inside the mill 10. For example, depending on the classification performance of the rotary classifier 16, the increase or decrease in the circulation amount of the pulverized solid fuel circulating inside the mill 10 between the vicinity of the rotary classifier 16 and the vicinity of the rotary table 12, and the corresponding increase or decrease in the differential pressure inside the mill 10 change. That is, since the pulverized fuel discharged from the outlet 19 can be adjusted and managed with respect to the solid fuel supplied inside the mill 10, the pulverized fuel in an amount corresponding to the supply amount of the solid fuel input to the mill 10 can be stably supplied to the burner unit 220 provided in the boiler 200, within a range where the particle size of the pulverized fuel does not affect the combustibility of the burner unit 220.
Furthermore, the state detection unit 40 of this embodiment is, for example, a temperature measurement means, which detects the temperature of the primary air supplied into the housing 11 to blow the solid fuel pulverized by the roller 13 up to the rotary classifier 16, and the temperature of the primary air inside the housing 11 up to the outlet 19, and controls the blower 30 so that the upper limit temperature is not exceeded. Note that the primary air is cooled by transporting the pulverized material while drying it inside the housing 11, so that the temperature from the upper space of the housing 11 to the outlet 19 is, for example, about 60 to 80 degrees.

The control unit 50 is a device that controls each part of the solid fuel pulverizing device 100. The control unit 50 may, for example, control the rotation speed of the rotary table 12 for the operation of the mill 10 by transmitting a drive command to the drive unit 14. The control unit 50 can adjust the classification performance by, for example, transmitting a drive command to the motor 18 of the rotary classifier 16 to control the rotation speed, thereby optimizing the differential pressure in the mill 10 within a predetermined range and stabilizing the supply of pulverized fuel. In addition, the control unit 50 can adjust the supply amount (coal supply amount) of solid fuel that the conveying unit 22 conveys the solid fuel and supplies to the fuel supply unit 17 by, for example, transmitting a drive command to the motor 23 of the coal feeder 20. In addition, the control unit 50 can control the opening degree of the hot gas damper 30c and the cold gas damper 30d by transmitting an opening degree command to the blower unit 30, thereby controlling the flow rate and temperature of the primary air. Specifically, the control unit 50 controls the hot gas damper 30c and the cold gas damper 30d so that the flow rate and outlet temperature of the carrier gas are set to predetermined values for the coal supply amount for each type of solid fuel.

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 in the form of a program, for example, and the CPU reads this program into the RAM and executes information processing and arithmetic processing 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. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

Next, a description will be given of the boiler 200 which generates steam by burning the pulverized fuel supplied from the solid fuel pulverizer 100.
As shown in FIG. 1 , the boiler 200 includes a furnace 210 and a burner unit 220 .

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

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

Next, the scraper (sweeping part) 70 will be described. As shown in FIG. 2, the scraper 70 is disposed below the rotary table 12. The scraper 70 has an arm part 71, one end of which is fixed to the rotary table 12, and a moving part 72 extending vertically downward from a free end of the arm part 71 (the end opposite to the end fixed to the rotation support part). The scraper 70 is rotatable coaxially with the rotary table 12. That is, the scraper 70 rotates about the central axis C1. In this embodiment, it rotates clockwise when viewed from above (see also the arrow R in FIG. 4A). The arm part 71 extends substantially horizontally in the direction of the side part 11b of the housing 11. The moving part 72 is disposed so that its lower end abuts against the bottom part 11d of the housing 11, and slides on the upper surface of the bottom part 11d.
An opening 11e is formed on the bottom surface 11d of the housing 11 and on the rotational orbit of the moving part 72. As shown in Figures 3 and 4, the opening 11e is a hole penetrating in the vertical direction, and in this embodiment, has, for example, a rectangular shape in plan view. The opening 11e is provided radially outward from the central axis C1. The scraper 70 guides the pulverized fuel accumulated on the bottom surface 11d to the opening 11e.

As shown in Figures 2 and 3, a discharge device 60 is provided below the opening 11e. The discharge device 60 includes a spillage chute (duct) 73 whose upstream end communicates with the opening 11e, an assist gas injection section (injection section) 74 that is provided inside the spillage chute 73 and injects assist gas, and a spillage hopper 75 that is connected to the downstream end of the spillage chute 73.

As shown in FIG. 3, the spillage chute 73 is a duct-like member provided below the opening 11e. Inside the spillage chute 73, the crushed fuel (in the following description, the crushed solid fuel remaining inside the housing 11 is also referred to as "residual charcoal") flows through the inside of the spillage chute 73. The spillage chute 73 is inclined at a predetermined angle with respect to the horizontal plane. In detail, the spillage chute 73 is inclined with respect to the horizontal plane over almost the entire area in the longitudinal direction and is formed so as not to have any portion extending in the vertical direction. The predetermined angle is set to an angle equal to or greater than the angle of repose of the crushed fuel. As a result, the residual charcoal, which is the crushed fuel, slides down suitably on the bottom surface 73d of the spillage chute 73, so that clogging of the spillage chute 73 can be suppressed. A gate valve 76 is provided midway in the spillage chute 73. Note that the term "residual charcoal" is a convenient name, and the solid fuel is not limited to coal.

The spillage chute 73 has an inlet opening 73a formed at the upstream end of the flow of the residual coal, and an outlet opening 73b formed at the downstream end of the flow of the residual coal. The spillage chute 73 also has a flange portion 73c that protrudes outward from the outer circumferential surface of the upstream end.

As shown in FIG. 3, the inlet opening 73a is connected to the opening 11e from below. As shown in FIG. 3 and FIG. 4, the inlet opening 73a is a hole that penetrates in the vertical direction and has a rectangular shape in a plan view. The inlet opening 73a is formed larger than the opening 11e formed in the bottom surface portion 11d of the housing 11. The inlet opening 73a is formed to be larger outward than the opening 11e. In addition, the inlet opening 73a and the opening 11e are arranged so that the entire opening 11e overlaps with the inlet opening 73a when the inlet opening 73a is viewed from above. In other words, all edges of the inlet opening 73a are located outside the edges of the opening 11e.

The outlet opening 73 b is a circular opening and communicates with the upper part of the spillage hopper 75 .
The flange portion 73c is a plate-like member. The flange portion 73c is a rectangular frame-like member provided over the entire circumferential area of the spillage chute 73. The upper surface of the flange portion 73c may be connected to the lower surface of the bottom surface portion 11d of the housing 11 in surface contact, or the upper surface of the connection flange portion 90 and the lower surface of the bottom surface portion 11d may be connected over a partial area or the entire area via a seal member. The flange portion 73c is formed with a plurality of through holes penetrating in the vertical direction. The plurality of through holes are formed in a line at a predetermined interval in the circumferential direction, and are fixed to the bottom surface portion 11d of the housing 11 by bolts 73e inserted through each through hole.

The assist gas injection unit 74 is provided inside the spillage chute 73 and injects an assist gas into the inside of the spillage chute 73. In this embodiment, for example, air can be used as the assist gas. Dry steam, inert gas such as nitrogen gas or carbon dioxide can also be used. When an inert gas is used, spontaneous combustion of the residual charcoal, which is the fuel after crushing, can be suppressed. In addition, when the discharge device 60 is a wet recovery method using water, water or steam can be injected instead of the assist gas. In this case, if water is injected to eliminate blockage and then the injection is stopped, there is a possibility that dry residual charcoal will accumulate again due to the moisture remaining on the inner wall of the spillage chute 73, so liquid such as water may be constantly injected even during normal operation.

As shown in FIG. 4A, the assist gas injection unit 74 has an injection pipe 77 that injects the assist gas, a supply pipe 78 that supplies the assist gas supplied from an assist gas supply device (not shown) to the injection pipe 77, and two flange joints 79 that connect the injection pipe 77 and the supply pipe 78. The assist gas injection unit 74 injects the assist gas from the direction near the bottom surface 73d of the spillage chute 73 toward the outlet opening 73b, and discharges the residual coal accumulated on the bottom surface 73d from the outlet opening 73b toward the inside of the spillage hopper 75.

As shown in FIG. 3, the injection pipe 77 is disposed near the bottom surface 73d of the spillage chute 73. The injection pipe 77 is disposed below the opening 11e and outside the opening 11e when the opening 11e is viewed in plan. That is, the injection pipe 77 is not disposed vertically below the opening 11e, but is disposed vertically below the bottom surface portion 11d of the housing 11. The injection pipe 77 is disposed near the inlet opening 73a of the spillage chute 73. That is, the injection pipe 77 of the assist gas injection section 74 is not disposed in the area vertically below the opening 11e. This makes it difficult for the residual coal that flows into the spillage chute 73 through the opening 11e to come into contact with or accumulate on the upper part of the assist gas injection section 74.

As shown in FIG. 4A, the injection pipe 77 penetrates the side wall of the spillage chute 73 and extends linearly in the width direction of the spillage chute 73. The injection pipe 77 extends along the rotation direction R of the scraper 70. Assist gas is introduced into the injection pipe 77.

In addition, multiple injection holes 77a (seven in this embodiment, for example) are formed on the side of the injection pipe 77 on the outlet opening 73b side. The multiple injection holes 77a are arranged at predetermined intervals (approximately equal intervals in this embodiment) along the extension direction of the injection pipe 77. Each injection hole 77a injects the assist gas that is introduced into the injection pipe 77 and flows through the injection pipe 77.

The injection pipe 77 injects the assist gas in the direction of the outlet opening 73b of the spillage chute 73 (see arrow A in Figures 3 and 5). Specifically, as shown in Figure 5, the injection pipe 77 injects the assist gas toward the area of the bottom surface 73d of the spillage chute 73 that is radially outward from the central axis C2 of the opening 11e with respect to the central axis C1 of the housing 11 as a reference. The graph in Figure 5 shows the relationship between the radial position of the opening 11e and the amount of residual coal discharged at that position. The amount of residual coal discharged indicates the amount of residual coal discharged by the scraper 70 from the opening 11e. As shown in Figure 5, the amount of residual coal discharged increases from the radial inner end toward the central axis C2, and is the largest at position P1, which is radially outward from the central axis C2. Also, the amount of residual coal discharged decreases from position P1, which is the peak, toward the radial outer end. In this embodiment, the assist gas is injected toward a target point P2 located vertically below the position P1 where the amount of residual carbon discharged is the greatest in the radial direction of the opening 11e.

Furthermore, a supply pipe 78 is connected to the end of the injection pipe 77 on the rear side (upstream side) in the rotation direction R of the scraper 70 via a flange joint 79. For this reason, among the multiple injection holes 77a, the injection pressure of the assist gas is greater toward the injection hole 77a on the supply pipe 78 side. That is, the injection pressure of the assist gas is greater for the injection hole 77a arranged on the rear side (upstream side) in the rotation direction R of the scraper 70 than for the injection hole 77a arranged on the front side (downstream side) in the rotation direction R.
Because scraper 70 passes above opening 11e, the residual coal guided by scraper 70 to opening 11e starts to fall into opening 11e from the rear side (upstream side) of opening 11e in the rotation direction R (in other words, the lower side of the paper in FIG. 4A). Therefore, the amount of residual coal flowing from opening 11e into spillage chute 73 is greater on the rear side (upstream side) in the rotation direction R of scraper 70 than on the front side (downstream side), which is preferable because the ejection pressure of the assist gas can be increased toward the side where the amount of residual coal is greater.

The supply pipe 78 supplies assist gas from an assist gas supply device (not shown) to the injection pipe 77. The supply pipe 78 is provided outside the spillage chute 73. As shown in FIG. 6A, the supply pipe 78 is provided with a supply pipe valve 78a. The supply pipe valve 78a is an on-off valve.

As shown in FIG. 4A, two flange joints 79 are provided: an injection pipe side flange joint 79a fixed to the injection pipe 77, and a supply pipe side flange joint 79b fixed to the supply pipe 78.

The injection pipe side flange joint 79a is fixed to the end of the injection pipe 77 on the supply pipe 78 side. As shown in FIG. 4B, the injection pipe side flange joint 79a is an annular member into which the injection pipe 77 is inserted. The injection pipe side flange joint 79a has a plurality of through holes 99 (eight in this embodiment, for example). The plurality of through holes 99 are arranged at predetermined intervals in the circumferential direction.

The supply pipe flange joint 79b is fixed to the end of the supply pipe 78 on the injection pipe 77 side. The shape of the supply pipe flange joint 79b is the same as that of the injection pipe flange joint 79a, so a detailed description is omitted. The supply pipe 78 is inserted inside the supply pipe flange joint 79b.

The injection pipe flange joint 79a and the supply pipe flange joint 79b are arranged so that all through holes are connected, and are fastened and fixed by bolts (not shown) that pass through each through hole. The injection pipe flange joint 79a and the supply pipe flange joint 79b are also fastened and fixed so that the injection hole 77a formed in the injection pipe 77 faces a predetermined direction. By removing each bolt, rotating the injection pipe flange joint 79a and the injection pipe 77, and fixing the injection pipe flange joint 79a and the supply pipe flange joint 79b with each bolt again, the direction of the assist gas injected from the injection hole 77a formed in the injection pipe 77 can be changed. Therefore, the direction in which the assist gas is injected can be set to a desired angle.

As shown in Fig. 3, the spillage hopper 75 is a box-shaped member having a space inside. The spillage hopper 75 in this embodiment is a so-called dry type spillage hopper. However, it may be a wet type spillage hopper.
A vent pipe 80 for reducing the pressure in the internal space is connected to the ceiling portion 75a of the spillage hopper 75. A vent valve 81 is provided in the vent pipe 80. By opening the vent valve 81, the internal space of the spillage hopper 75 is connected to the external space of the spillage hopper 75. This allows the pressure inside the spillage hopper 75 to be reduced.

The vent valve 81 may be opened when assist gas is injected from the assist gas injection section 74. This makes it possible to suppress an increase in the internal pressure of the spillage hopper 75 when the assist gas is injected. This makes it possible to suppress backflow of the assist gas and a decrease in the injection pressure. In addition, it is possible to reduce the pressure difference between the inside of the housing 11 and the inside of the spillage hopper 75, facilitating the discharge of residual coal.

The timing for opening the vent valve 81 may be simultaneous with the injection of the assist gas, or may be a predetermined time after the injection of the assist gas. It may also be a predetermined time before the injection of the assist gas.

Next, the operation of the mill 10 according to this embodiment will be described.

[Normal operation]
First, the operation of the mill 10 during normal operation will be described with reference to Fig. 2. Note that normal operation refers to a state in which solid fuel is supplied from the fuel supply unit 17 to the turntable 12 and solid fuel is pulverized on the turntable 12.

When solid fuel is supplied from the fuel supply unit 17 onto the rotating turntable 12, the roller 13 presses and pulverizes the solid fuel on the turntable 12. A part of the pulverized fuel, which is the pulverized solid fuel, is scattered from the turntable 12 to the radial outside of the turntable 12 due to the centrifugal force of the turntable 12. The scattered pulverized fuel is supplied from the primary air duct 27 and rises while being dried by the primary air that passes through the outlet 25. The pulverized fuel that rises is classified by the rotary classifier 16, and particles larger than a predetermined particle size fall as coarse fuel and are returned to the turntable 12 for re-pulverization. On the other hand, particles smaller than the predetermined particle size pass through the rotary classifier 16 as fine fuel, ride the primary air flow, and are discharged from the outlet 19 to the outside of the housing 11. Foreign objects such as gravel and metal pieces mixed in the solid fuel, and crushed fuel that is too heavy to be transported by primary air, fall from the outer periphery of the rotating table 12 to the bottom surface 11d of the housing 11. The remaining charcoal and foreign objects (also referred to as "spillage" in the following explanation) that are crushed fuel that fall to the bottom surface 11d are guided by the scraper 70 through the opening 11e to the spillage chute 73 and discharged to the spillage hopper 75 outside the housing 11.

[Emergency stop]
Next, an operation performed when the mill 10 according to this embodiment is stopped in an emergency will be described. When the mill 10 detects an abnormality or the like, the mill 10 makes an emergency stop. When the mill 10 makes an emergency stop, the supply of solid fuel from the fuel supply unit 17, the rotation of the turntable 12, and the introduction of primary air from the primary air duct 27 may be stopped. In such a case, the pulverized fuel on the turntable 12 remains on the turntable 12. In addition, a part of the pulverized fuel that was being transported by the primary air falls and accumulates on the turntable 12 or on the bottom surface 11d of the housing 11. At this time, since the rotation of the turntable 12 has stopped, the rotation of the scraper 70 has also stopped. Therefore, the scraper 70 does not discharge the remaining coal on the bottom surface 11d.

When the mill 10 is stopped in an emergency, an operation is performed to reduce the oxygen concentration in the housing 11 (oxygen concentration reduction operation). Specifically, nitrogen or steam is supplied as an inert gas into the housing 11 to reduce the oxygen concentration in the housing 11, thereby suppressing the natural oxidation temperature rise and ignition of the remaining charcoal in the housing 11.

When it is determined that the oxygen concentration in the housing 11 has sufficiently decreased and the natural oxidation temperature rise and ignition of the residual charcoal have been suppressed, an operation (clearing operation) is then performed to discharge the residual charcoal in the housing 11. When the clearing operation is started, the turntable 12 is rotated first. This causes the scraper 70 to rotate as well. By rotating the turntable 12, the residual charcoal on the turntable 12 is scattered by centrifugal force and falls to the bottom surface portion 11d of the housing 11. The residual charcoal accumulated on the bottom surface portion 11d is guided by the scraper 70 to the opening 11e and flows into the spillage chute 73. The residual charcoal that flows into the spillage chute 73 flows through the spillage chute 73 and is discharged to a spillage hopper 75 provided outside the housing 11. At this time, an assist gas may be injected into the spillage chute 73 by the assist gas injection unit 74.
In this way, the remaining charcoal in the housing 11 is discharged, and natural oxidation temperature rise and ignition of the remaining charcoal in the housing 11 are suppressed.

[Assist gas injection timing]
Next, the timing at which the assist gas ejection unit 74 ejects the assist gas will be described with reference to FIGS. 6A and 6B. FIG.
In the solid fuel pulverizer 100 of this embodiment, the control unit 50 sets the amount of assist gas injected from the assist gas injection unit 74 based on the load of the mill 10. Specifically, the control unit 50 of this embodiment injects assist gas during clearing operation when the load is zero or during low-load (low coal feed) operation of the mill 10. This is based on the knowledge that the amount of residual coal deposited on the bottom surface 11d is maximized during clearing operation because the supply of primary air is stopped. Also, during low-load operation of the mill 10, the flow rate of primary air is controlled to be low in response to the decrease in the coal feed rate, so that the amount of spillage discharged increases.

In detail, as shown in Fig. 6B, when the load (coal supply amount) of the mill 10 is equal to or greater than the minimum (min) load and equal to or less than a predetermined value L1 load, the control unit 50 opens the supply pipe valve 78a and injects a predetermined amount of assist gas. When the load of the mill 10 is greater than the predetermined value L1 load, the control unit 50 closes the supply pipe valve 78a and stops injecting the assist gas. The predetermined value L1 load is, for example, greater than the minimum (min) load and less than 50% load.
Furthermore, when the clearing operation is started, the supply pipe valve 78a is opened to inject a predetermined amount of assist gas.

The timing of assist gas injection is not limited to the above description. For example, as shown in FIG. 7B, the amount of assist gas injected may be changed based on the load of the mill 10. In this case, as shown in FIG. 7A, a branch pipe 82 may be provided for the supply pipe 78 so as to bypass the supply pipe valve 78a. The branch pipe 82 is arranged in parallel with the supply pipe 78. The branch pipe 82 is provided with a branch pipe valve 83 and an orifice 84. The branch pipe valve 83 is an opening/closing valve.

In the example shown in FIG. 7B, when the load of the mill 10 is equal to or greater than the minimum (min) load and equal to or less than a predetermined load value L1, the control unit 50 opens the supply pipe valve 78a and injects a predetermined amount of assist gas. When the load of the mill 10 is greater than the predetermined load value L1 and equal to or less than 100% load, the control unit 50 closes the supply pipe valve 78a and opens the branch pipe valve 83. In this state, the assist gas is supplied to the jet pipe via the branch pipe valve 83. The branch pipe valve 83 is provided with an orifice 84. Therefore, the amount of assist gas supplied to the jet pipe via the branch pipe valve 83 is smaller than the amount supplied to the jet pipe via the supply pipe 78. Therefore, the amount of assist gas injected is also smaller.
When the clearing operation is started, the branch pipe valve 83 is closed and the supply pipe valve 78a is opened to inject a predetermined amount of assist gas. This makes it possible to suppress the accumulation of residual carbon due to the injection of assist gas while suppressing the amount of assist gas used.

Also, for example, as shown in FIG. 8B, the amount of assist gas injected may be changed depending on the load of the mill 10. In this case, as shown in FIG. 8A, a flow control valve 85 is provided in the supply pipe 78 instead of the supply pipe valve 78a. The flow control valve 85 can adjust the flow rate of the assist gas flowing through the inside of the supply pipe 78 by adjusting the opening degree.

In the example shown in Fig. 8B, when the load of the mill 10 is equal to or greater than the minimum (min) load and equal to or less than a predetermined load value L1, the control unit 50 opens the flow rate control valve 85 almost fully (the rated flow rate opening of the control valve) and injects a predetermined amount of assist gas. When the load of the mill 10 is greater than the predetermined load value L1 and equal to or less than 100% load, the control unit 50 adjusts the opening of the flow rate control valve 85 according to the load. Specifically, the opening of the flow rate control valve 85 is reduced as the load increases, thereby reducing the amount of assist gas injected. Even when the load of the mill 10 is 100% load, the amount of assist gas injected is not set to zero, but a certain amount is injected.
In addition, when the clearing operation is started, the flow rate control valve 85 is opened almost fully (the rated flow rate opening of the control valve) to inject a predetermined amount of assist gas. This makes it possible to suppress the accumulation of residual carbon due to the injection of assist gas while suppressing the amount of assist gas used.

This embodiment provides the following advantageous effects.
Most of the residual charcoal, which is the pulverized fuel that flows into the spillage chute 73 through the opening 11e, falls into the area vertically below the opening 11e. In this embodiment, the assist gas injection section 74 (particularly the injection pipe 77) is provided outside the opening 11e when the opening 11e is viewed from above. In other words, the assist gas injection section 74 is not provided in the area vertically below the opening 11e. This makes it difficult for the residual charcoal that flows into the spillage chute 73 through the opening 11e to come into contact with or accumulate on the upper part of the assist gas injection section 74. This makes it possible to make it difficult for the residual charcoal to accumulate on the assist gas injection section 74. This makes it possible to suppress blockage of the spillage chute 73.

In this embodiment, the spillage chute 73 extends from the connection portion with the opening 11e so as to be inclined with respect to the horizontal plane. This allows the vertical length (height) of the discharge device 60 to be shorter than a spillage chute that has a portion extending perpendicularly (in other words, vertically) to the horizontal plane at the connection portion with the opening 11e and is then connected to the portion and inclined with respect to the horizontal plane. This allows the installation cost of the discharge device 60 to be reduced. The discharge device 60 is also disposed at the bottom of the mill 10. This allows the vertical length (height) of the entire solid fuel pulverization device 100 to be reduced by reducing the height of the discharge device 60, thereby reducing the construction cost. In addition, the supporting steel frame of the solid fuel pulverization device 100 may be integral with the supporting steel frame of the boiler 200. Therefore, the supporting steel frames of the solid fuel pulverization device 100 and the boiler 200 can be integrated to reduce the construction cost.

The inlet opening 73a of the spillage chute 73 is formed to be larger outward than the opening 11e formed in the housing 11. This allows the flow passage cross section of the spillage chute 73 to be made sufficiently large relative to the amount of residual coal flowing into the spillage chute 73, thereby preventing the spillage chute 73 from being blocked by residual coal.

In addition, in this embodiment, the scraper 70 that guides the residual charcoal to the opening 11e rotates. As a result, the residual charcoal guided by the scraper 70 moves radially outward due to centrifugal force while being guided. Therefore, the amount of residual charcoal flowing from the opening 11e into the spillage chute 73 is greater on the outside than on the inside in the radial direction (see the graph in Figure 5). In this embodiment, the assist gas injection unit 74 injects assist gas radially outward from the central axis C2 of the opening 11e. This makes it possible to inject assist gas into an area where a large amount of residual charcoal flows in and is prone to clogging. Therefore, clogging of the spillage chute 73 can be more effectively suppressed.

In this embodiment, the opening 11e is formed on the rotation orbit of the scraper 70. That is, the scraper 70 passes above the opening 11e. Therefore, the remaining charcoal guided to the opening 11e by the scraper 70 starts to fall from the rear side (upstream side, in other words, the lower side of the paper in FIG. 4A) of the opening 11e in the rotation direction R. Therefore, the amount of remaining charcoal flowing from the opening 11e into the spillage chute 73 is greater on the rear side than on the front side (downstream side, in other words, the upper side of the paper in FIG. 4A) of the rotation direction R. In this embodiment, since the connection position of the supply pipe 78 that supplies assist gas to the injection pipe 77 is on the rear side (upstream side, in other words, the lower side of the paper in FIG. 4A) of the rotation direction R, the injection pressure of the injection hole 77a on the rear side of the rotation direction R is greater than that of the injection hole 77a on the front side of the rotation direction R. As a result, it is possible to inject assist gas with a high injection pressure into an area where a large amount of remaining charcoal flows in and is prone to clogging. This makes it possible to more effectively prevent blockage of the spillage chute 73.

[Modification 1]
Next, a modification (modification 1) of this embodiment will be described with reference to FIG.
This modified example differs from the first embodiment in that a connection flange portion 90 is provided. Other points are similar to those of the first embodiment, so the same components are given the same reference numerals and detailed descriptions thereof are omitted.
As described above, the connection flange portion 90 is provided between the flange portion 73c of the spillage chute 73 and the bottom surface portion 11d of the housing 11. The connection flange portion 90 is a rectangular frame-shaped member with an opening 90a formed in the central region. The opening 90a formed in the connection flange portion 90 has substantially the same shape and size as the opening 11e formed in the bottom surface portion 11d of the housing 11. The connection flange portion 90 is arranged so that the inner edge of the frame of the opening 90a formed in the connection flange portion 90 and the inner edge of the opening 11e formed in the bottom surface portion 11d are substantially continuous. The upper surface of the connection flange portion 90 may be connected to the lower surface of the bottom surface portion 11d in surface contact, or the upper surface of the connection flange portion 90 and the lower surface of the bottom surface portion 11d may be connected to each other via a seal member in a partial region or the entire region. The connection flange portion 90 is formed with a plurality of through holes penetrating in the vertical direction, and the through holes on the lower surface side of the connection flange portion 90 are formed as stepped holes with a large size. The connection flange portion 90 and the housing 11 are fixed by a first bolt 91 which passes through a through hole formed in the connection flange portion 90 and screws into a bolt hole (female thread portion) formed in the bottom surface portion 11d of the housing 11. At this time, the bolt head portion of the first bolt 91 may be housed in a large stepped hole portion of the through hole on the underside of the connection flange portion 90 so as not to interfere with the connection with the flange portion 73c of the spillage chute 73.
The lower surface of the connection flange portion 90 is connected to the upper surface of the flange portion 73c in surface contact or via a seal member. The connection flange portion 90 has a plurality of bolt holes (female threaded portions) formed outside the through holes. Each bolt hole communicates with a through hole formed in the flange portion 73c. The connection flange portion 90 and the flange portion 73c are fixed by a second bolt 92 that passes through a through hole formed in the flange portion 73c and screws into the bolt hole.

By providing the connection flange portion 90 in this manner, it is possible to install and fix the spillage chute 73 having an inlet opening 73a larger than the opening 11e to the existing mill 10. That is, by providing the connection flange portion 90, it is possible to fix the spillage chute 73 to the housing 11 by utilizing the existing bolt holes formed on the underside of the bottom portion 11d. This makes it possible to easily replace the existing mill 10 with a spillage chute 73 having an inlet opening 73a larger than the opening 11e.
In this modified example, the injection pipe 77 of the assist gas injection part 74 is not provided in the area vertically below the opening 11e, so that the residual coal that flows into the spillage chute 73 through the opening 11e is less likely to come into contact with or accumulate on the upper part of the assist gas injection part 74. This makes it possible to suppress clogging of the spillage chute 73.

[Modification 2]
Next, a modification (modification 2) of this embodiment will be described with reference to FIG.
This modified example differs from the first embodiment mainly in that the spillage chute 73A has a vertical portion 93 and a recessed portion 95. Other points are the same as those in the first embodiment, so the same components are given the same reference numerals and detailed descriptions thereof are omitted.

The spillage chute 73A according to this modification has a portion that extends vertically relative to the horizontal plane at the connection portion with the opening 11e, a vertical portion 93 that communicates with the opening 11e, and an inclined portion 94 that bends from the lower end of the vertical portion 93 and extends diagonally downward so as to be inclined relative to the horizontal plane. An inlet opening 93a is formed at the upstream end of the vertical portion 93. The shape of the inlet opening 93a is substantially the same as that of the opening 11e. The vertical portion 93 is arranged so that the inner edge of the inlet opening 93a and the inner edge of the opening 11e are substantially continuous. A flange portion 73c is provided on the outer peripheral surface of the vertical portion 93, and the spillage chute 73A is fixed to the bottom portion 11d of the housing 11 by a bolt 73e that penetrates the flange portion 73c.

A recess 95 is formed at the upper end of the bottom surface of the inclined portion 94, which is connected to the lower end of the vertical portion 93, and protrudes toward the central axis C1 of the housing 11. That is, the recess 95 is provided so as to form a space that protrudes outward from the opening 11e when the opening 11e is viewed in plan. The recess 95 accommodates the injection pipe 77 of the assist gas injection portion 74. The bottom surface 95a of the recess 95 is inclined so that the inclined portion 94 side is located downward. This makes it difficult for residual charcoal to accumulate on the bottom surface 95a of the recess 95. That is, it makes it difficult for residual charcoal to accumulate inside the recess 95.

In this modified example, the injection pipe 77 of the assist gas injection section 74 is also provided outside the opening 11e when the opening 11e is viewed in plan. This makes it difficult for the residual charcoal that flows into the spillage chute 73A through the opening 11e to accumulate on the assist gas injection section 74. This makes it possible to suppress blockage of the spillage chute 73A.

[Modification 3]
Next, a modification (Modification 3) of this embodiment will be described with reference to FIG.
This modified example differs from the first embodiment in that the spillage chute 73A has a vertical portion 93 and a recess 96. It also differs from the first embodiment in that an assist gas duct 97 is provided instead of the assist gas ejection portion 74. Since the other points are the same as those in the first embodiment, the same components are denoted by the same reference numerals and detailed descriptions thereof are omitted.

Spillage chute 73B according to this modification has a portion that extends vertically relative to the horizontal plane at the connection portion with opening 11e, and has a vertical portion 93 that communicates with opening 11e, and an inclined portion 94 that bends from the lower end of vertical portion 93 and extends obliquely downward so as to be inclined relative to the horizontal plane. The configurations of vertical portion 93 and inclined portion 94 are similar to those of vertical portion 93 and inclined portion 94 according to modification 2 described above, and therefore the same reference numerals are used and detailed description thereof will be omitted.
At the connection position between the lower end side of the vertical portion 93 and the bottom surface of the upper end side of the inclined portion 94, a recess 96 of a space protruding toward the central axis C1 side of the housing 11 is formed. The recess 96 is provided so as to form a space protruding outward from the opening 11e when the opening 11e is viewed in a plan view. An assist gas duct 97 is accommodated in the recess 96. The assist gas duct 97 and the internal space of the spillage chute 73B are separated by a partition wall 98. A communication hole 98a is formed in the partition wall 98. The communication hole 98a communicates the assist gas duct 97 and the internal space of the spillage chute 73B. Assist gas is introduced into the assist gas duct 97 and flows therethrough, and the assist gas in the assist gas duct 97 is injected into the internal space of the spillage chute 73B through the communication hole 98a. That is, in this modified example, the assist gas duct 97 has an assist gas injection function similar to that of the injection pipe 77 of the first embodiment.

In this modified example, the assist gas duct 97 is provided outside the opening 11e when the opening 11e is viewed in plan. This makes it difficult for residual charcoal that flows into the spillage chute 73B through the opening 11e to accumulate on the assist gas duct 97. This makes it possible to prevent blockage of the spillage chute 73B.

The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present disclosure.
For example, in the above embodiment, an example in which the inclination angle of the spillage chute 73 is equal to or greater than the repose angle has been described, but the present disclosure is not limited thereto. The inclination angle of the spillage chute may be set to be equal to or less than the repose angle when the assist gas is ejected from the assist gas ejection section 74. By setting the inclination angle of the spillage chute to be equal to or less than the repose angle, the vertical length (height) of the spillage chute can be shortened compared to the case in which the inclination angle of the spillage chute is equal to or greater than the repose angle. In addition, in the above embodiment, by providing the assist gas ejection section 74 on the spillage chute 73, clogging of the spillage chute can be suppressed even if the inclination angle of the spillage chute is equal to or less than the repose angle. This allows the overall height of the solid fuel pulverization device 100 to be lowered, and the construction costs of the solid fuel pulverization device 100 and the boiler 200 can be further reduced.

In addition, in the above embodiment, an example has been described in which the shape of the opening 11e formed in the bottom surface portion 11d of the housing 11 is rectangular in plan view, but the present disclosure is not limited to this. For example, the shape of the opening formed in the bottom surface portion 11d of the housing 11 may be a polygonal shape other than a rectangle in plan view, or may be circular in plan view.

In addition, a portion of the supply pipe 78 that supplies assist gas to the injection pipe 77 may be formed from a flexible member (e.g., a flexible hose). With this configuration, the supply pipe can be deformed, which reduces layout restrictions on the supply pipe. This allows the installation space for the supply pipe to be reduced. In addition, the flexible member attenuates vibrations transmitted from the mill 10. This makes it possible to suppress the transmission of vibrations to the injection pipe 77.

In the above embodiment, the injection pressure of the injection holes 77a arranged on the rear side in the rotation direction R of the scraper 70 is greater than that of the injection holes 77a arranged on the front side in the rotation direction R, but the present disclosure is not limited to this. For example, the amount of assist gas injected may be greater in the rear region in the rotation direction R of the scraper 70 than in the front region in the rotation direction R. Methods for increasing the injection amount include increasing the diameter of the injection holes 77a arranged in the rear region in the rotation direction R, and shortening the interval between the multiple injection holes 77a arranged in the rear region in the rotation direction R. By configuring in this way, the amount of assist gas injected can be increased in the rear region in the rotation direction R where the amount of residual carbon discharged is large, so that residual carbon can be discharged preferably.

In the above embodiment, an example has been described in which the control unit 50 adjusts the amount of assist gas injected from the assist gas injection unit 74 and the injection timing based on the load of the mill 10, but the present disclosure is not limited to this. For example, the control unit 50 may detect blockage of the spillage chute 73 by detecting the pressure difference between the pressure in the space below the turntable 12 and the pressure inside the spillage hopper 75 and monitoring the pressure difference. When the spillage chute 73 is blocked, the pressure difference increases, and therefore it may be determined that a blockage has occurred when the pressure difference exceeds a predetermined value.
Furthermore, when the control unit 50 determines that a blockage has occurred, the amount of assist gas injected from the assist gas injection unit 74 may be temporarily increased to a value greater than the injection amount set according to the amount of coal fed (mill load) to eliminate the blockage. Furthermore, after the blockage is eliminated, the injection amount of assist gas may be set to return to the amount corresponding to the amount of coal fed (mill load) when the differential pressure returns to normal.

The discharge device, solid fuel pulverizer, boiler system, and discharge device operation method described in each of the above-described embodiments can be understood, for example, as follows.

The discharge device according to one aspect of the present disclosure is a discharge device (60) that discharges pulverized solid fuel from an opening (11e) provided in a housing (11) that forms the outer shell of a pulverizer (10) that pulverizes solid fuel, and includes a duct (73) that is provided below the opening (11e), communicates with the opening (11e), and through which the pulverized solid fuel discharged from the opening (11e) flows, and an injection unit (74) that is provided inside the duct (73) and injects a fluid into the duct (73), and the injection unit (74) is provided below the opening (11e) and outside the opening (11e) when the opening (11e) is viewed in plan.

Most of the pulverized solid fuel that flows into the duct through the opening falls into the area vertically below the opening. In the above configuration, the injection section is provided outside the opening when the opening is viewed from above. In other words, the injection section is not provided in the area vertically below the opening. This makes it difficult for the pulverized solid fuel that flows into the duct through the opening to come into contact with the upper part of the injection section. This makes it difficult for the pulverized solid fuel to accumulate on the injection section. This makes it possible to suppress blockage of the pulverized solid fuel in the duct.

In addition, in the exhaust device according to one aspect of the present disclosure, the duct (73) has an inlet opening (73a) that communicates with the opening (11e), extends from the inlet opening (73a) at an angle relative to the horizontal plane, and the inlet opening (73a) is formed to be larger in size than the opening (11e).

In the above configuration, the duct extends from the inlet opening so as to be inclined with respect to the horizontal plane. That is, the duct is inclined with respect to the horizontal plane at the portion communicating with the opening. This allows the vertical length (height) of the exhaust device to be shorter than that of a duct extending from the inlet opening in a direction perpendicular to the horizontal plane (in other words, in the vertical direction). This allows the installation cost of the exhaust device to be reduced. In particular, for example, when the exhaust device is disposed at the bottom of the pulverizer, the vertical length (height) of the entire pulverizer can be reduced, thereby reducing the construction costs of the pulverizer and the boiler.
In addition, the inlet opening of the duct is formed larger than the opening formed in the housing. This makes it possible to easily avoid providing the injection unit in an area vertically below the opening formed in the housing, making it difficult for the pulverized solid fuel to accumulate on the injection unit, and the injection unit can be provided near the inlet opening of the duct to effectively inject fluid onto the pulverized solid fuel. This makes it possible to effectively inject fluid onto the pulverized solid fuel while forming the flow passage cross section of the duct sufficiently large relative to the amount of pulverized solid fuel flowing into the duct, thereby suppressing clogging of the pulverized solid fuel in the duct.

A solid fuel pulverization device according to one aspect of the present disclosure includes any one of the discharge devices (60) described above and the pulverizer (10) that pulverizes the solid fuel, and the pulverizer (10) includes:
The housing (11) is accommodated therein and has a rotating table (12) that rotates about a central axis (C1) extending in the vertical direction, and has a crushing section (12, 13) that crushes the solid fuel on the rotating table (12), and a sweeping section (70) that is provided below the rotating table (12) and rotates and moves around the central axis (C1) on the upper surface of the bottom section (11d) of the housing (11) to guide the crushed solid fuel accumulated on the bottom section to an opening (11e) formed in the housing (11), the opening (11e) being radially outside the central axis (C1) and formed on the orbit of the sweeping section (70) that rotates and moves.

In addition, in the solid fuel pulverization device according to one embodiment of the present disclosure, the injection section (74) injects the fluid radially outward from the center of the opening (11e).

In the above configuration, the sweeping section that guides the pulverized solid fuel accumulated on the bottom surface of the housing to the opening rotates. As a result, the pulverized solid fuel guided by the sweeping section moves radially outward due to centrifugal force while being guided. Therefore, the amount of pulverized solid fuel flowing from the opening into the duct is greater on the radially outer side than on the radially inner side. In the above configuration, the injection section injects fluid radially outward rather than toward the center of the opening. This makes it possible to inject fluid toward an area where a large amount of pulverized solid fuel flows in and which is more likely to become clogged. Therefore, clogging of the duct can be more effectively suppressed.

In addition, in the solid fuel pulverization device according to one embodiment of the present disclosure, the injection section (74) has a plurality of injection holes (77a) for injecting a fluid, and the plurality of injection holes (77a) are arranged in a line along the rotational direction (R) in which the sweep section (70) rotates and moves, and the injection pressure for injecting the fluid is greater on the rear side of the rotational direction (R) of the sweep section (70) than on the front side of the rotational direction (R).

In the above configuration, an opening is formed on the orbit of the sweeping section. That is, the sweeping section passes above the opening. Therefore, the pulverized solid fuel guided to the opening by the sweeping section starts to fall from the rear side (upstream side) of the opening in the direction of rotation. Therefore, the amount of pulverized solid fuel flowing from the opening into the duct is greater on the rear side than on the front side (downstream side) in the direction of rotation. In the above configuration, the injection pressure of the fluid is greater in the injection holes on the rear side of the rotation direction than in the injection holes on the front side of the rotation direction. This allows a large amount of pulverized solid fuel to flow in, and a fluid with a high injection pressure can be injected into an area that is prone to clogging. Therefore, clogging of the duct can be more effectively suppressed.

A boiler system according to one aspect of the present disclosure includes a solid fuel pulverizer (100) as described above, and a boiler (200) that burns the solid fuel pulverized by the solid fuel pulverizer (100) to generate steam.

The method of operating the discharge device according to one aspect of the present disclosure is a method of operating a discharge device (60) that discharges pulverized solid fuel from an opening (11e) provided in a housing that forms the outer shell of a crusher (10) that crushes solid fuel, the discharge device (60) having a duct (73) that is provided below the opening (11e), communicates with the opening (11e), and through which the pulverized solid fuel discharged from the opening (11e) flows, and an injection unit (74) that is provided inside the duct (73) and outside the opening (11e) when the opening (11e) is viewed in plan, and that injects a fluid into the duct (73), and includes an injection step of injecting the fluid from the injection unit (74).

1: Boiler system 10: Mill (crusher)
11: Housing
11a : Inner circumferential surface 11b : Side surface portion 11d : Bottom surface portion 11e : Opening 12 : Rotary table 13 : Roller 14 : Drive unit 16 : Rotary classifier 16a : Blade 17 : Fuel supply unit 18 : Motor 19 : Outlet 20 : Coal feeder 21 : Bunker 22 : Conveyor unit 23 : Motor 24 : Downspout unit 25 : Outlet 26 : Vane 27 : Primary air duct 30 : Blower unit 30a : Hot gas flow path 30b : Cold gas flow path 30c : Hot gas damper 30d : Cold gas damper 31 : Primary air ventilator 32 : Forced air ventilator 34 : Heat exchanger 40 : Status detection unit 41 : Bottom surface portion 42 : Ceiling portion 45 : Journal head 47 : Support arm 48 : Support shaft 49 : Pressing device 50 : Control unit 60 : Discharge device 70 : Scraper (sweeping part)
71: Arm portion 72: Moving portion 73: Spillage chute 73A: Spillage chute 73B: Spillage chute 73a: Inlet opening 73b: Outlet opening 73c: Flange portion 73d: Bottom surface 73e: Bolt 74: Assist gas injection portion (injection portion)
75: Spillage hopper 75a: Ceiling portion 76: Gate valve 77: Injection pipe 77a: Injection hole 78: Supply pipe 78a: Supply pipe valve 79: Flange joint 79a: Injection pipe side flange joint 79b: Supply pipe side flange joint 80: Vent pipe 81: Vent valve 82: Branch pipe 83: Branch pipe valve 84: Orifice 85: Flow rate control valve 90: Connection flange portion 90a: Opening 91: First bolt 92: Second bolt 93: Vertical portion 94: Inclined portion 95: Recess 95a: Bottom surface 96: Recess 97: Assist gas duct 98: Partition portion 98a: Communication hole 100: Solid fuel pulverizer 100a: Primary air flow path 100b: Supply flow path 200: Boiler 210: Furnace 220: Burner portion

Claims (7)

A discharge device that discharges pulverized solid fuel from an opening provided in a housing that forms an outer shell of a pulverizer that pulverizes the solid fuel,
a duct provided below the opening, communicating with the opening, through which the pulverized solid fuel discharged from the opening flows;
an ejection unit provided inside the duct and configured to eject a fluid into the duct;
The ejection portion is provided below the opening and outside the opening when the opening is viewed from above. The duct has an inlet opening communicating with the opening, and extends from the inlet opening at an angle with respect to a horizontal plane,
The exhaust system of claim 1 , wherein the inlet opening is sized larger than the opening. An ejection device according to claim 1 or 2;
a pulverizer for pulverizing the solid fuel,
The crusher is
a crushing unit that is accommodated inside the housing and has a rotary table that rotates about a central axis that extends in a vertical direction, and crushes the solid fuel on the rotary table;
a sweeping section that is provided below the rotary table and rotates around the central axis on an upper surface of the bottom section of the housing to guide the pulverized solid fuel that has accumulated on the bottom section to an opening formed in the housing,
The opening is formed radially outward of the central axis and on the track of the sweeping part which rotates. The solid fuel pulverizer according to claim 3, wherein the injection section injects fluid radially outward from the center of the opening. The injection portion has a plurality of injection holes for injecting a fluid,
A solid fuel pulverization device as described in claim 3 or claim 4, wherein the multiple injection holes are arranged in a row along the rotational direction in which the sweeping section rotates and moves, and the injection pressure for injecting the fluid is greater on the rear side of the rotational direction of the sweeping section than on the front side of the rotational direction. A solid fuel pulverizer according to any one of claims 3 to 5,
a boiler for burning the solid fuel pulverized by the solid fuel pulverizer to generate steam;
A boiler system equipped with A method for operating a discharge device that discharges pulverized solid fuel from an opening provided in a housing that forms an outer shell of a pulverizer that pulverizes the solid fuel, comprising the steps of:
The discharge device includes:
a duct provided below the opening, communicating with the opening, through which the pulverized solid fuel discharged from the opening flows;
an ejection portion that is provided inside the duct and outside the opening when the opening is viewed in a plan view, and that ejects a fluid into the inside of the duct;
A method for operating an ejection device, comprising the step of ejecting fluid from the ejection portion.

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