Method for operating solid fuel pulverizer, solid fuel pulverizer, and boiler facility

Abstract

To provide a method for operating a solid fuel pulverizer capable of easily eliminating overload caused by accumulated solid fuel.SOLUTION: When a supply amount of solid fuel increases, a flow rate of carrier gas increases according to a reference flow rate associated with the supply amount of the solid fuel. When a load on a solid fuel pulverizer exceeds a predetermined value, the supply amount of the solid fuel is reduced, and the flow rate of the carrier gas is set to a flow rate larger than the reference flow rate corresponding to the reduced supply amount of the solid fuel. The load is determined by at least one of mill differential pressure and mill furnace differential pressure.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for operating a solid fuel pulverizer, a solid fuel pulverizer, and a boiler installation. [Background technology]

[0002] Solid fuel such as biomass fuel or coal is pulverized into fine powder having a particle size of a predetermined size or less in a pulverizer (mill), and then supplied to a combustion device of a boiler via a pulverized fuel supply line. The mill is a facility that crushes solid fuel fed onto a crushing table by pinching it between the crushing table and crushing rollers, then uses a classifier to select finely divided fuel particles of a specified particle size or smaller from the crushed solid fuel, and transports the selected finely divided fuel together with carrier gas (primary air) to the boiler via a finely divided fuel supply line. A boiler is a facility that generates combustion gas by burning transported pulverized fuel in a combustion device, and generates steam by heat exchange between the generated combustion gas and water. In a thermal power plant, steam generated in a boiler is used to rotate a steam turbine, which in turn rotates a generator connected to the steam turbine, thereby generating electricity.

[0003] Conventionally, the flow rate of primary air supplied to a mill is controlled so as to increase or decrease in association with an increase or decrease in the amount of fuel supplied, as disclosed in Patent Document 1, for example (see A2 in FIG. 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-133930 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Document 1, when the flow rate of primary air increases or decreases in accordance with the increase or decrease in the amount of fuel supplied, that is, when the flow rate of primary air increases or decreases at the same rate of change (the slope in a graph) whether the amount of fuel supplied is increased or decreased, if an overload occurs in the mill or the pulverized fuel supply line and the amount of solid fuel supplied to the mill is reduced to eliminate the overload, the flow rate of primary air will decrease at the same rate of change as when it increased.

[0006] However, if the flow rate of the primary air is reduced at the same rate as when it was increased, the ability of the primary air to transport the pulverized fuel will decrease, making it easier for the pulverized fuel to stagnate in the mill and the pulverized fuel supply line, which will not only fail to eliminate the overload but may actually increase the load.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide an operating method for a solid fuel pulverizer, as well as a solid fuel pulverizer and boiler equipment, that can easily eliminate overload caused by accumulated solid fuel. [Means for solving the problem]

[0008] In order to solve the above problems, the operating method of the solid fuel pulverizer, the solid fuel pulverizer, and the boiler facility of the present disclosure employ the following means.

[0009] A method for operating a solid fuel pulverization device according to one aspect of the present disclosure is a method for operating a solid fuel pulverization device comprising: a housing; a rotary table disposed inside the housing and rotating about a central axis; a fuel supply unit that supplies solid fuel to the rotary table; a crushing roller disposed inside the housing and gripping the solid fuel between the rotary table and the solid fuel to crush it; a carrier gas supply line that supplies a carrier gas for transporting the crushed solid fuel to an inlet of the housing; and a pulverized fuel supply line that supplies the carrier gas and the crushed solid fuel from an outlet of the housing to a boiler, wherein when the supply amount of the solid fuel increases, the flow rate of the carrier gas increases according to a standard flow rate linked to the supply amount of the solid fuel, and when the load of the solid fuel pulverization device exceeds a predetermined value, the supply amount of the solid fuel is reduced, and the flow rate of the carrier gas is set to a flow rate greater than the standard flow rate corresponding to the supply amount of the solid fuel after the reduction.

[0010] In addition, a solid fuel pulverization device according to one aspect of the present disclosure includes a housing, a rotary table provided inside the housing and rotating around a central axis, a fuel supply unit that supplies solid fuel to the rotary table, a crushing roller that grinds the solid fuel by gripping it between the rotary table and the roller, a carrier gas supply line that supplies a carrier gas for transporting the pulverized solid fuel to an inlet of the housing, a pulverized fuel supply line that supplies the carrier gas and the pulverized solid fuel from an outlet of the housing to a boiler, and a control unit, wherein when the supply amount of the solid fuel increases, the flow rate of the carrier gas increases according to a standard flow rate linked to the supply amount of the solid fuel, and when the load exceeds a predetermined value, the control unit reduces the supply amount of the solid fuel and sets the flow rate of the carrier gas to a flow rate greater than the standard flow rate corresponding to the supply amount of the solid fuel after the reduction.

[0011] Moreover, a boiler facility according to one aspect of the present disclosure includes a solid fuel pulverizer, and the boiler that generates steam by burning the solid fuel pulverized by the solid fuel pulverizer in a combustion device. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a method for operating a solid fuel pulverizer, a solid fuel pulverizer, and a boiler facility that can easily eliminate overload caused by accumulated solid fuel. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a power plant equipped with a solid fuel pulverizer according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing the main part of the solid fuel pulverizer of FIG. 1. [Figure 3] 4 is a graph showing the relationship between the amount of fuel supplied and the primary air flow rate. [Figure 4] 1 is a flowchart of a method of operating a solid fuel pulverizer according to an embodiment of the present disclosure. [Figure 5] In an operating method of a solid fuel pulverizer according to one embodiment of the present disclosure, graph (a-1) shows the relationship between time and mill differential pressure, graph (a-2) shows the relationship between time and mill furnace differential pressure, graph (b) shows the relationship between time and fuel supply amount, and graph (c) shows the relationship between time and primary air supply amount. [Figure 6] 10 is a graph showing the relationship between time and the amount of primary air supplied in the method of operating a solid fuel pulverizer according to Modification 3. [Figure 7] 10 is a graph showing the relationship between time and the amount of primary air supplied in the method of operating a solid fuel pulverizer according to Modification 3. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a method for operating a solid fuel pulverizer, a solid fuel pulverizer, and a boiler facility according to an embodiment of the present disclosure will be described with reference to the drawings. In the following explanation, "upper" in terms such as "top" and "top surface" refers to the part above the vertical. Similarly, "lower" refers to the part below the vertical. However, the vertical direction is not precise and may include errors.

[0015] [Configuration of solid fuel pulverizer] The power plant 1 includes a boiler facility including a solid fuel pulverizer 100 and a boiler 200, and a power generation section (not shown).

[0016] The solid fuel pulverizer 100 is a device that generates pulverized fuel by pulverizing solid fuel such as coal or biomass fuel, and supplies the pulverized fuel to a burner 220 (combustion device) of a boiler 200. The solid fuel may be coal, biomass fuel, petroleum coke (PC), or the like. Furthermore, these solid fuels may be used in combination. In the power plant 1 shown in FIG. 1, the number of solid fuel pulverizers 100 is one. However, the power plant 1 may include a plurality of solid fuel pulverizers 100. For example, the power plant 1 may include the solid fuel pulverizers 100 in a number corresponding to the number of burners 220 included in one boiler 200.

[0017] As shown in Figures 1 and 2, the solid fuel pulverizer 100 includes a mill 10 (pulverizer), a fuel supply unit having a bunker 21 and a fuel supply device 20, a blower unit 30 (carrier gas supply unit), a carrier gas supply line 110, a pulverized fuel supply line 120, and a control unit 50.

[0018] The mill 10 includes a housing 11, a grinding table 12 (rotary table), grinding rollers 13, a reducer 14, a mill motor 15 (drive unit) connected to the reducer 14 to rotate the grinding table 12, a rotary classifier 16 (classification unit), a fuel supply pipe 17, and a classifier motor 18 to rotate the rotary classifier 16.

[0019] The housing 11 is formed in a cylindrical shape extending in the vertical direction, and is a case that houses the crushing table 12, the crushing rollers 13, the rotary classifier 16, and a part of the fuel supply pipe 17 (a part including the lower end). The shape of the housing 11 may be changed as appropriate depending on the shape of the components to be housed. For example, if the outer shape of the rotary classifier 16 is large, the diameter of the housing 11 may be increased only around the rotary classifier 16.

[0020] A reducer 14 is installed near the bottom surface 41 of the housing 11. A mill motor 15 is connected to the reducer 14. The milling table 12 is configured to rotate around a rotation axis L1 (central axis) by a driving force transmitted from a mill motor 15 via a reducer .

[0021] The crushing table 12 is a portion that is formed into a substantially circular shape when viewed from above in the direction of the rotation axis L1, and is disposed so that its central portion faces the lower end of the fuel supply pipe 17. As shown in FIG. 2, the upper surface of the grinding table 12 forms a smoothly inclined surface that is higher in the center, becomes lower as it approaches the periphery from the center, and then becomes higher again. The shape of the upper surface of the rotary table 12 may be changed as appropriate. For example, the upper surface of the rotary table 12 may be an inclined surface that is low in the center and becomes higher as it approaches the periphery from the center.

[0022] A fuel supply pipe 17 is attached to the center of the ceiling portion 42 of the housing 11. The fuel supply pipe 17 is a part that supplies solid fuel guided from the fuel supply section into the inside of the housing 11, and is arranged vertically at the center position of the housing 11, with the part including the lower end being located inside the housing 11. The fuel supply pipe 17 supplies solid fuel toward the center of the upper surface of the grinding table 12 . The crushing table 12 sandwiches the supplied solid fuel in a biting portion 70 formed between the crushing table 12 and the crushing roller 13 .

[0023] The crushing roller 13 is a rotating body that crushes the solid fuel supplied onto the crushing table 12 from the fuel supply pipe 17 . The crushing roller 13 is pressed against the upper surface of the crushing table 12 and cooperates with the crushing table 12 to crush the solid fuel. 1 and 2 show only one representative crushing roller 13, but multiple crushing rollers 13 are arranged at regular intervals in the circumferential direction so as to press against the upper surface of the crushing table 12. For example, three crushing rollers 13 are arranged at equal intervals in the circumferential direction, spaced apart by an angle of 120 degrees around the rotation axis L1. In this case, the portions of the three crushing rollers 13 that come into contact with the upper surface of the crushing table 12 (pressing portions) are equidistant from the central axis of rotation of the crushing table 12.

[0024] The crushing roller 13 is configured to be able to swing and displace up and down by the journal head 45. Therefore, the crushing roller 13 can move closer to or away from the upper surface of the crushing table 12. In other words, the crushing roller 13 can swing and displace freely, increasing or decreasing the distance between it and the upper surface of the crushing table 12. When the crushing table 12 rotates with the outer circumferential surface of the crushing roller 13 in contact with the solid fuel on the upper surface of the crushing table 12, the crushing roller 13 receives a rotational force from the crushing table 12 and rotates together with the solid fuel. When solid fuel is supplied from the fuel supply pipe 17, the solid fuel is pressed and crushed in the biting portion 70 formed between the crushing roller 13 and the crushing table 12, forming a fuel layer 72 on the upper surface of the crushing table 12. The force with which the crushing roller 13 presses the solid fuel at this time is called the "crushing load."

[0025] A support arm 47 of the journal head 45 is accommodated in the housing 11 and is supported by a support shaft 48 that extends in the horizontal direction. The support arm 47 supports the crushing roller 13 so that it can swing about a support shaft 48. The swinging crushing roller 13 has a component of displacement in the up and down direction.

[0026] A pressing device 49 is provided at the upper end of the support arm 47 on the vertically upper side. The pressing device 49 is fixed to the housing 11 . The pressing device 49 applies a crushing load to the crushing roller 13 via the support arm 47 etc. so that the crushing roller 13 is pressed against the crushing table 12 . The crushing load is applied, for example, by a hydraulic cylinder (not shown) that operates 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). The method of supporting the crushing roller 13 and the method of applying the crushing load are not limited to these. For example, the support shaft 48 of the crushing roller 13 may be directly pressed downward by a hydraulic cylinder (not shown).

[0027] When solid fuel is fed into the center of the grinding table 12 from the fuel supply pipe 17, the centrifugal force generated by the rotation of the grinding table 12 guides the solid fuel to the outer periphery of the grinding table 12, where it is pinched between the grinding table 12 and the grinding rollers 13 and crushed. The pulverized solid fuel is blown upward by a carrier gas (hereinafter referred to as "primary air") introduced from a carrier gas inlet 11a (inlet) of the housing 11 connected to a carrier gas supply line 110, and is introduced into a rotary classifier 16.

[0028] An outlet (not shown) is provided on the outermost periphery of the grinding table 12 or on the part of the housing 11 facing the outer peripheral surface of the grinding table 12, which allows the primary air flowing in from the carrier gas inlet 11a to flow out into the space above the grinding table 12. A swirl vane (not shown) is installed at the outlet, and applies a swirling force to the primary air blown out from the outlet. The primary air given a swirling force by the swirl vane becomes an airflow with a swirling velocity component, and transports the solid fuel pulverized on the pulverizing table 12 (hereinafter referred to as "pulverized fuel") to the rotary classifier 16 located above in the housing 11. The swirl blades may be installed on the grinding table 12 and rotate together with the grinding table 12, or may be installed on the housing 11.

[0029] The pulverized fuel having a particle size larger than a predetermined particle size is classified by the rotary classifier 16 or falls without reaching the rotary classifier 16, returns to the pulverizing table 12, and is pulverized again between the pulverizing table 12 and the pulverizing roller 13.

[0030] As shown in FIGS. 1 and 2, the rotary classifier 16 is provided at the upper part inside the housing 11, and has a hollow inverted cone or cylindrical outer shape. The rotary classifier 16 is provided with a plurality of blades 16a extending in the vertical direction at its outer periphery. The blades 16a are provided at predetermined intervals (equal intervals) around the central axis of the rotary classifier 16. Here, the central axis of the rotary classifier 16 coincides with the rotation axis L1. The rotary classifier 16 is a device that classifies pulverized fuel into particles larger than a predetermined particle size (for example, approximately 70 μm to 100 μm for coal) (hereinafter, pulverized fuel larger than the predetermined particle size will be referred to as "coarse pulverized fuel") and particles smaller than the predetermined particle size (hereinafter, pulverized fuel smaller than the predetermined particle size will be referred to as "fine pulverized fuel"). The rotary classifier 16 is rotationally driven by a classifier motor 18 controlled by the control unit 50. The rotary classifier 16 rotates around a fuel supply pipe 17, centering on a cylindrical axis (not shown) extending in the up-down direction of the housing 11. The classifying section may be, for example, a fixed classifier having a fixed hollow inverted cone-shaped casing and a plurality of fixed swirling blades on the outer periphery of the casing instead of the blades 16a. The classifying section may also be a combination of a rotary classifier and a stationary classifier.

[0031] 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 (outlet) in the ceiling portion 42 of the housing 11. The pulverized fuel classified by the rotary classifier 16 (arrow A1 in FIG. 2) is discharged from the outlet port 19 to the pulverized fuel supply line 120 together with the primary air (arrow A2 in FIG. 2) and supplied to the burner 220 of the boiler 200.

[0032] The fuel supply device 20 of the fuel supply unit is connected to the bunker 21 via the downspout portion 24. The downspout portion 24 is a pipe that extends downward from the lower end portion of the bunker 21. A valve (coal gate) for switching the discharge state of the solid fuel from the bunker 21 may be provided midway in the downspout portion 24 (not shown). The fuel supply device 20 includes a conveying unit 22 and a coal feeder motor 23 . The conveying section 22 is, for example, a belt conveyor, and conveys the solid fuel discharged from the lower end of the downspout section 24 to the upper end of the fuel supply pipe 17 by the driving force of the coal feeder motor 23, and then feeds it into the inside of the fuel supply pipe 17. The amount of solid fuel supplied to the mill 10 (hereinafter also referred to as the "fuel supply amount") is controlled by a signal from the control unit 50, for example, by adjusting the movement speed of the belt conveyor of the transport unit 22.

[0033] Normally, primary air is supplied inside the mill 10 to transport the pulverized fuel to the burner 220 of the boiler 200, so the pressure inside the mill 10 is higher than the pressure inside the fuel supply device 20 and the pressure inside the bunker 21. Solid fuel is layered inside the downspout 24 that connects the bunker 21 and the fuel supply device 20. This layer of solid fuel ensures a sealing property (material sealing property) that prevents primary air and pulverized fuel from flowing back from the mill 10 toward the bunker 21.

[0034] When the solid fuel is biomass fuel (e.g., biomass pellets), the pellets stacked in downspout section 24 have a generally uniform size and shape compared to coal. For example, coal before pulverization is in the form of lumps measuring 2 mm to 50 mm, whereas biomass pellets are cylindrical and homogeneous, with a diameter of 6 mm to 8 mm and a length of 40 mm or less. Therefore, when biomass pellets are stacked in downspout section 24, the gaps formed between the biomass pellets are larger than those between coal, and the sealing ability (material sealing ability), which is the effect of filling the gaps due to particles of different sizes and shapes, is reduced. As a result, the primary air inside the mill 10 passes through gaps formed in the layer inside the downspout section 24 and flows back from inside the mill 10 through the downspout section 24 to the bunker 21, which increases the possibility of the pressure inside the mill 10 decreasing compared to when coal fuel is used. If the pressure inside the mill 10 drops, various problems may occur in the stable operation of the solid fuel pulverizer 100 and boiler 200, such as a deterioration in the transportability of pulverized fuel inside the mill 10, the generation of dust inside the fuel supply device 20 and above the bunker 21, ignition of pellets inside the fuel supply device 20, bunker 21, or downspout section 24 due to the high temperature of the primary air, and a decrease in the amount of pulverized fuel transported to the burner 220. Therefore, a rotary valve 60 (see Figure 2) may be provided in the fuel supply pipe 17 connecting the fuel supply device 20 to the inside of the mill 10 to suppress the occurrence of backflow of primary air and pulverized fuel from the inside of the mill 10 through the fuel supply device 20 and downspout section 24 to the bunker 21.

[0035] The blower 30 is a device that blows primary air into the housing 11 to dry the pulverized fuel and transport it to the rotary classifier 16 . The blower section 30 includes, for example, a primary air fan (PAF) 31, a hot gas flow path 30a, a cold gas flow path 30b, a hot gas damper 30c, and a cold gas damper 30d in order to appropriately adjust the flow rate and temperature of the primary air being blown.

[0036] The hot gas flow path 30a supplies part of the air sent out from the primary air ventilator 31 as hot gas that has been heated by passing through an air preheater 34 (heat exchanger). 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. The hot gas flow passage 30a may be provided with a blocking damper (not shown) for blocking the flow of hot gas. The opening and closing of the blocking damper may be controlled by the control unit 50 or may be operated manually.

[0037] The cold gas flow path 30b supplies a part of the air sent out from the primary air ventilator 31 as cold gas at room temperature. The cold gas flow path 30b is provided with a cold gas damper 30d. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The flow rate of the cold gas supplied from the cold gas flow path 30b is determined by the opening degree of the cold gas damper 30d. The cold gas flow passage 30b may be provided with a blocking damper (not shown) for blocking the flow of cold gas. The opening and closing of the blocking damper may be controlled by the control unit 50 or may be operated manually.

[0038] 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 passage 30a and the cold gas supplied from the cold gas passage 30b. Furthermore, the oxygen concentration in the primary air blown from the carrier gas supply line 110 into the housing 11 may be adjusted by introducing a portion of the combustion gas discharged from the boiler 200 into the hot gas flow path 30a and mixing the portion of the combustion gas with the hot gas flowing through the hot gas flow path 30a. By adjusting the oxygen concentration in the primary air, for example, when using a solid fuel that is highly ignitable (easily ignited), the possibility of the solid fuel igniting in the path from the mill 10 to the burner 220 of the boiler 200 can be reduced. Here, the combustion gas is introduced into the hot gas flow path 30a by, for example, a gas recirculation fan (not shown).

[0039] The boiler 200 includes a furnace 210 and a burner 220. The boiler 200 is a facility that generates combustion gas by burning pulverized fuel supplied from the solid fuel pulverizer 100, and generates steam by heat exchange between the generated combustion gas and water.

[0040] The burner 220 is a device that burns pulverized fuel to form a flame using a mixture of primary air and pulverized fuel supplied from the pulverized fuel supply line 120, and secondary air that is supplied by heating air (outside air) sent out from a forced draft fan (FDF) 32 using an air preheater 34. The pulverized fuel is combusted inside the furnace 210, and the high-temperature combustion gas passes through heat exchangers such as an evaporator, a superheater, and a coal economizer (not shown) before being discharged outside the boiler 200.

[0041] The combustion gas discharged from the boiler 200 undergoes predetermined treatment in environmental equipment (such as a denitration device, dust collector, and desulfurization device, not shown), and then undergoes heat exchange with primary air and secondary air in an air preheater 34.Then, the combustion gas is guided via an induced draft fan (IDF) 33 to a chimney (not shown) and released into the outside air. The air heated by the combustion gas in the air preheater 34 and delivered from the primary air fan 31 is supplied to the above-mentioned hot gas flow path 30a.

[0042] 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 become high-temperature, high-pressure superheated steam. The superheated steam is sent to a steam turbine (not shown), which is one of the components that make up the power generation section, and drives the steam turbine to rotate. The steam turbine is connected to a generator (not shown), which is one of the devices that make up the power generation section, via a rotating shaft, and the rotation of the steam turbine drives the generator to generate electricity.

[0043] The solid fuel pulverizer 100 further includes a state detection unit. The state detection unit is, for example, at least one of a mill state detection unit 40 and a line state detection unit 121. The data measured or detected by the state detection unit is sent to the control unit 50.

[0044] The control unit 50 is composed of, for example, a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), and a computer-readable storage medium. A series of processes for implementing various functions is stored in a storage medium, for example, in the form of a program. The CPU reads the program into the RAM and executes information processing and arithmetic operations to implement 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.

[0045] The mill state detection unit 40 is, for example, a differential pressure measurement means provided in the mill 10. The differential pressure measuring means is configured to measure the mill differential pressure. The mill differential pressure is the difference between the pressure at the point (carrier gas inlet 11a) where primary air flows into the inside of the housing 11 from the carrier gas supply line 110 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 line 120.

[0046] The increase or decrease in the mill differential pressure corresponds to the increase or decrease in the solid fuel or pulverized fuel accumulated inside the mill 10. The accumulation of solid fuel or pulverized fuel inside the mill 10 means that the pulverized fuel is not being properly supplied to the pulverized fuel supply line 120, that is, the pulverized fuel is not being properly supplied to the boiler 200. This mill differential pressure is considered to be one of the load indicators that indicates the load state of the solid fuel pulverizer 100 .

[0047] The line state detection unit 121 is, for example, a differential pressure measurement means provided in the pulverized fuel supply line 120. The differential pressure measuring means is configured to measure the mill furnace differential pressure. The mill furnace differential pressure is the difference between the pressure at the outlet port 19 of the housing 11 and the pressure in the furnace 210 of the boiler 200. The mill furnace differential pressure is also the difference between the pressure at the inlet of the pulverized fuel supply line 120 (i.e., the pressure at the outlet port 19 of the housing 11) and the pressure at the outlet of the pulverized fuel supply line 120.

[0048] The mill furnace differential pressure can be considered, for example, as the sum of the pressure loss caused by the primary air flowing inside the pulverized fuel supply line 120 and the pressure loss caused when the pulverized fuel is pushed out inside the pulverized fuel supply line 120. The increase or decrease in the mill furnace differential pressure corresponds to the increase or decrease in the pulverized fuel accumulated in the pulverized fuel supply line 120. The accumulation of pulverized fuel in the pulverized fuel supply line 120 means that the pulverized fuel is not being supplied to the boiler 200 appropriately. This mill furnace pressure difference is considered to be one of the load indicators that indicates the load state of the solid fuel pulverizer 100 .

[0049] Monitoring the mill furnace differential pressure is particularly useful when the solid fuel is a biomass fuel (eg, biomass pellets). Generally, the particle size of pulverized biomass pellets is larger than that of pulverized coal. Therefore, when biomass pellets are used as solid fuel, clogging and accumulation of fuel easily occur in the pulverized fuel supply line 120. Therefore, by monitoring the mill furnace differential pressure, accumulation of fuel in the pulverized fuel supply line 120 can be detected quickly. Even when coal is used as the solid fuel, depending on the properties and state of the coal (e.g., moisture content), clogging and retention may easily occur in the pulverized fuel supply line 120. Therefore, it is meaningful to monitor the mill furnace differential pressure regardless of the type of solid fuel.

[0050] The control unit 50 is a device that controls each part of the solid fuel pulverizer 100 . The control unit 50 adjusts the amount of solid fuel supplied to the mill 10, for example, by transmitting a drive command to the coal feeder motor 23. The control unit 50, for example, controls the opening degrees of the hot gas damper 30c and the cold gas damper 30d by transmitting opening degree instructions for the hot gas damper 30c and the cold gas damper 30d to the blower unit 30, thereby adjusting the flow rate and temperature of the primary air.

[0051] [Regarding primary air flow rate control] The control of the flow rate of primary air will be described with reference to FIGS.

[0052] As shown in Figure 3, when the fuel supply amount is increased, the primary air flow rate (shown by the dotted line) is linked to the fuel supply amount. Specifically, the primary air flow rate is set to increase in accordance with the increase in the fuel supply amount. Even more specifically, the primary air flow rate is set to increase linearly in accordance with the increase in the fuel supply amount (however, this does not include the low-load operation region not shown in Figure 3). Therefore, when the fuel supply amount is increased, the primary air flow rate is uniquely determined based on the desired fuel supply amount. Here, the primary air flow rate that is uniquely determined based on the desired fuel supply amount when the fuel supply amount is increased is defined as the "reference flow rate." The reference flow rate is located on the dotted line in Figure 3. Note that this embodiment does not include a case where the reference flow rate is kept constant regardless of an increase in the fuel supply amount.

[0053] On the other hand, when the fuel supply amount is reduced in a predetermined case, the primary air flow rate (shown by the solid line) is set so as not to decrease according to the reference flow rate. Specifically, the primary air flow rate is set to be greater than the reference flow rate. In the case of FIG. 3, when the fuel supply amount is reduced from S1 to S2, the primary air flow rate is set to Fa. Fa is, for example, the reference flow rate of the primary air flow rate corresponding to the fuel supply amount before reduction (S1), and is greater than Fb, which is the reference flow rate of the primary air flow rate corresponding to the fuel supply amount after reduction (S2). The above-mentioned "predetermined case" refers to a case where the load on the solid fuel pulverizer 100 exceeds a predetermined value (a preset standard). Whether the load on the solid fuel pulverizer 100 exceeds a predetermined value is determined by whether at least one of the mill differential pressure and the mill furnace differential pressure exceeds a predetermined value. A state in which the load on the solid fuel pulverizer 100 exceeds a predetermined value is called "overload." In the case of FIG. 3, it is determined that an overload has occurred in the solid fuel pulverizer 100 when the fuel supply amount is S1. If the fuel supply amount is to be reduced when no overload is occurring, the primary air flow rate may be reduced in accordance with the reference flow rate.

[0054] The control of the primary air flow rate explained with reference to FIG. 3 is applied to the operation of the solid fuel pulverizer 100, for example, as follows. As shown in FIGS. 4 and 5, it is monitored whether at least one of the mill differential pressure and the mill furnace differential pressure exceeds a predetermined value set therefor, i.e., whether both the mill differential pressure and the mill furnace differential pressure are equal to or less than the predetermined value set therefor (steps S11 and S12 in FIG. 4).

[0055] If at least one of the mill differential pressure and the mill furnace differential pressure exceeds a predetermined value (if at least one of step S11 and step S12 is judged as "NO"), it is determined that an overload has occurred due to the accumulation of solid fuel (including pulverized fuel) (t1 in Figure 5), and the fuel supply amount is reduced to a predetermined value while maintaining the primary air flow rate as it is (step S21 in Figure 4, t1 to t2 in Figure 5). This results in the gradual elimination of the overload caused by the accumulation of solid fuel (the increased mill differential pressure and mill furnace differential pressure gradually decrease), or the rate of increase in the load caused by the accumulation of solid fuel is reduced (the rate of increase in the mill differential pressure and mill furnace differential pressure is reduced).

[0056] The two-dot chain line in FIG. 5(c) shows the case where the amount of primary air supplied is reduced in accordance with the reference flow rate at the same time as the amount of fuel supplied is reduced (conventional operating method). The two-dot chain lines in Figures 5(a-1) and 5(a-2) show the changes in the mill differential pressure and mill furnace differential pressure when the primary air supply rate is reduced in accordance with the reference flow rate. These are examples for reference and are not included in this embodiment.

[0057] The fuel supply amount and the primary air flow rate are maintained for a predetermined time (Δt (=t3-t2) in FIG. 5) after the fuel supply amount has been reduced to a predetermined value. After a predetermined time has elapsed, the primary air flow rate is gradually reduced to a reference flow rate corresponding to the reduced fuel supply amount (step S22 in FIG. 4, t3 to t4 in FIG. 5).

[0058] After the primary air flow rate has been reduced (t4 in FIG. 5), the fuel supply rate and primary air flow rate are maintained (step S23 in FIG. 4, t4 onward in FIG. 5), while monitoring is performed to determine whether at least one of the mill differential pressure and the mill furnace differential pressure exceeds a predetermined value, i.e., whether both the mill differential pressure and the mill furnace differential pressure are equal to or lower than a predetermined value (steps S24 and S25 in FIG. 4). Thereafter, steps S23 to S25 are repeated.

[0059] When both the mill differential pressure and the mill furnace differential pressure become equal to or less than a predetermined value (when the determinations in steps S24 and S25 are "YES"), the fuel supply rate is increased (step S31 in FIG. 4). The fuel supply rate is increased until it returns to the fuel supply rate before the decrease, for example. Furthermore, while the fuel supply rate is being increased, the primary air flow rate is increased according to the reference flow rate corresponding to that fuel supply rate. When the fuel supply amount has been increased, the control sequence ends, and then the control sequence starts again, and this process is repeated thereafter.

[0060] [Variation 1] The load indicator showing the load state of the solid fuel pulverizer 100 may be either the mill differential pressure or the mill furnace differential pressure. In this case, the control is simplified.

[0061] [Variation 2] The load indicator showing the load state of the solid fuel pulverizer 100 is not limited to the mill differential pressure or the mill furnace differential pressure. For example, the grinding table differential pressure may be used as the load index. The grinding table differential pressure is the differential pressure between the top and bottom of the grinding table 12. A specific example of the grinding table differential pressure is the differential pressure between the carrier gas inlet 11a below the grinding table 12 and the pressure just before the rotary classifier 16 above the grinding table 12. Alternatively, the mill power may be used as the load index. The mill power is the power of the mill motor 15 that rotates the grinding table 12. In addition, the lift amount of the crushing roller 13 (the distance between the upper surface of the crushing table 12 and the lower surface of the crushing roller 13, which is an index showing the amount of solid fuel on the crushing table 12) or the oil pressure of the hydraulic cylinder serving as the pressing device 49 may also be used as the load index. Any other index that reflects the load state of the solid fuel pulverizer 100 (degree of accumulation of solid fuel (including pulverized fuel)) can be used as appropriate.

[0062] [Variation 3] In FIG. 5, the primary air flow rate is maintained from t1 to t2, but if the primary air flow rate is higher than the reference flow rate, it is not necessarily required to maintain the primary air flow rate. For example, as shown in FIG. 6, the primary air flow rate may be increased from t1 to t2 and maintained from t2 to t3. Also, for example, as shown in FIG. 7, the primary air flow rate may be reduced in a range greater than the reference flow rate from t1 to t2, and maintained at the same level from t2 to t3.

[0063] The method of operating the solid fuel pulverizer, the solid fuel pulverizer, and the boiler facility according to the present embodiment described above can be understood as follows.

[0064] A method of operating a solid fuel pulverizer (100) according to a first aspect of the present disclosure includes a housing (11), a rotary table (12) provided inside the housing (11) and rotating about a central axis (L1), a fuel supply unit that supplies solid fuel to the rotary table (12), a crushing roller (13) provided inside the housing (11) and gripping and crushing the solid fuel between the rotary table (12), a carrier gas supply line (110) that supplies a carrier gas for transporting the crushed solid fuel to an inlet (11a) of the housing (11), and a fuel supply unit that supplies a carrier gas for transporting the crushed solid fuel to the inlet (11a) of the housing (11). and a pulverized fuel supply line (120) that supplies gas and the pulverized solid fuel from an outlet (19) of the housing (11) to a boiler (200), wherein when the supply amount of the solid fuel increases, the flow rate of the carrier gas increases according to a reference flow rate linked to the supply amount of the solid fuel, and when the load of the solid fuel pulverizer (100) exceeds a predetermined value, the supply amount of the solid fuel is reduced, and the flow rate of the carrier gas is set to a flow rate greater than the reference flow rate corresponding to the supply amount of the solid fuel after the reduction.

[0065] When the solid fuel accumulation causes an overload in the solid fuel pulverizer (100), the rate of increase of the accumulated solid fuel can be suppressed by reducing the supply amount of solid fuel. Also, by setting the flow rate of the carrier gas to a flow rate higher than the reference flow rate corresponding to the reduced supply amount of solid fuel, the discharge of the accumulated solid fuel can be promoted more efficiently than when the flow rate of the carrier gas is set to the reference flow rate corresponding to the reduced supply amount of solid fuel. This makes it easier to eliminate overload caused by accumulated solid fuel.

[0066] In the second aspect of the present disclosure, the operating method of the solid fuel pulverization device (100) of the first aspect is such that, when a predetermined time has elapsed after the supply amount of the solid fuel is reduced, the flow rate of the carrier gas is set to the reference flow rate corresponding to the supply amount of the solid fuel after the reduction.

[0067] When a predetermined time has elapsed after the supply amount of solid fuel is reduced, the flow rate of the carrier gas is set to a standard flow rate corresponding to the supply amount of solid fuel after the reduction, so that the flow rate of the carrier gas can be returned to the standard flow rate when it becomes highly likely that the overload has been resolved.

[0068] In the operating method of the solid fuel pulverization device (100) according to the third aspect of the present disclosure, in the second aspect, when the load returns to a predetermined value or less, the supply amount of the solid fuel is increased and the flow rate of the carrier gas is increased according to the reference flow rate.

[0069] When the load returns to a predetermined value or less, the supply amount of solid fuel is increased and the flow rate of the carrier gas is increased according to the reference flow rate, so that after it is confirmed that the overload has been eliminated, the operating state of the solid fuel pulverizer (100) can be returned to, for example, a normal state.

[0070] In the operating method of the solid fuel pulverizer (100) according to the fourth aspect of the present disclosure, in any one of the first to third aspects, the load is determined by at least one of a mill differential pressure, which is the differential pressure between the inlet (11a) and the outlet (19) of the housing (11), and a mill furnace differential pressure, which is the differential pressure between the outlet (19) of the housing (11) and a furnace (210) of the boiler (200).

[0071] The load is determined by at least one of the mill furnace differential pressure, which is the differential pressure between the outlet (19) of the housing (11) and the furnace (210) of the boiler (200), and the mill differential pressure, which is the differential pressure between the inlet (11a) of the housing (11) and the outlet (19), so that it is possible to grasp parameters that can efficiently monitor the load of at least one of the solid fuel pulverizer (100) and the pulverized fuel supply line (120).

[0072] A solid fuel pulverizer (100) according to a fifth aspect of the present disclosure includes a housing (11), a rotary table (12) provided inside the housing (11) and rotating about a central axis (L1), a fuel supply unit that supplies solid fuel to the rotary table (12), a crushing roller (13) that crushes the solid fuel by gripping it between the rotary table (12) and the fuel supply unit, a carrier gas supply line (110) that supplies a carrier gas for conveying the crushed solid fuel to an inlet (11a) of the housing (11), and a crushing unit (112) that crushes the solid fuel. and a pulverized fuel supply line (120) that supplies the pulverized solid fuel from an outlet (19) of the housing (11) to a boiler (200), and a control unit (50), wherein when the supply amount of the solid fuel increases, the flow rate of the carrier gas increases according to a reference flow rate linked to the supply amount of the solid fuel, and when the load exceeds a predetermined value, the control unit (50) reduces the supply amount of the solid fuel and sets the flow rate of the carrier gas to a flow rate higher than the reference flow rate corresponding to the supply amount of the solid fuel after the reduction.

[0073] In the solid fuel pulverization device (100) according to the sixth aspect of the present disclosure, in the fifth aspect, the load is determined by at least one of a mill differential pressure, which is the differential pressure between the inlet (11a) and the outlet (19) of the housing (11), and a mill furnace differential pressure, which is the differential pressure between the outlet (19) of the housing (11) and the furnace (210) of the boiler (200).

[0074] A boiler facility according to a seventh aspect of the present disclosure includes the solid fuel pulverizer (100) according to the fifth aspect, and a boiler (200) that generates steam by burning the solid fuel pulverized by the solid fuel pulverizer (100) in a combustion device. [Explanation of symbols]

[0075] 1. Power Plant 10 mils 11. Housing 11a Carrier gas inlet (inlet) 12 Grinding table (rotary table) 13 Crushing roller 14 Reducer 15 Mill motor (drive unit) 16 Rotary classifier 16a blade 17 Fuel supply pipe 18 Classifier motor 19 Exit port (exit) 20 Fuel supply device 21 Banka 22 Conveyor 23 Coal feeder motor 24 Downspout 30 Blower 30a Hot gas flow path 30b Cold gas flow path 30c Thermal Gas Damper 30d Cold Gas Damper 31 Primary air ventilator 34 Air preheater 40 Mill state detection unit 41 Bottom part 42 Ceiling 45 Journal Head 47 Support Arm 48 Support shaft 49 Pressing device 50 control section 60 Rotary Valve 70 Biting part 72 Fuel layer 100 Solid fuel crusher 110 Carrier gas supply line 120 Pulverized fuel supply line 121 Line status detection unit 200 boiler 210 Furnace 220 Burner A1 Pulverized fuel flow A2 Primary air flow L1 Rotation axis (central axis)

Claims

1. Housing and a rotary table provided inside the housing and rotatable about a central axis; a fuel supply unit that supplies solid fuel to the rotary table; a crushing roller provided inside the housing and configured to crush the solid fuel by pinching it between the roller and the rotary table; a carrier gas supply line for supplying a carrier gas for transporting the pulverized solid fuel to an inlet of the housing; a pulverized fuel supply line for supplying the carrier gas and the pulverized solid fuel from an outlet of the housing to a boiler; A method of operating a solid fuel pulverizer comprising: When the supply amount of the solid fuel increases, the flow rate of the carrier gas increases according to a reference flow rate associated with the supply amount of the solid fuel, When the load of the solid fuel pulverizer exceeds a predetermined value, Decreasing the supply amount of the solid fuel; The flow rate of the carrier gas is set to a flow rate greater than the reference flow rate corresponding to the reduced supply amount of the solid fuel. Method for operating a solid fuel pulverizer.

2. When a predetermined time has elapsed after the supply amount of the solid fuel is reduced, the flow rate of the carrier gas is set to the reference flow rate corresponding to the supply amount of the solid fuel after the reduction.

2. A method for operating a solid fuel pulverizer according to claim 1.

3. When the load returns to a predetermined value or less, increasing the supply amount of the solid fuel; Increasing the flow rate of the carrier gas according to the reference flow rate.

3. A method for operating a solid fuel pulverizer according to claim 2.

4. The load is a mill differential pressure, which is the pressure difference between the inlet and the outlet of the housing; and Mill furnace differential pressure, which is the pressure difference between the outlet of the housing and the furnace of the boiler It is judged by at least one of the following: A method for operating the solid fuel pulverizer according to any one of claims 1 to 3.

5. Housing and a rotary table provided inside the housing and rotatable about a central axis; a fuel supply unit that supplies solid fuel to the rotary table; a crushing roller that crushes the solid fuel by pinching it between itself and the rotary table; a carrier gas supply line for supplying a carrier gas for transporting the pulverized solid fuel to an inlet of the housing; a pulverized fuel supply line for supplying the carrier gas and the pulverized solid fuel from an outlet of the housing to a boiler; control unit, Equipped with When the supply amount of the solid fuel increases, the flow rate of the carrier gas increases according to a reference flow rate associated with the supply amount of the solid fuel, When the load exceeds a predetermined value, the control unit Decreasing the supply amount of the solid fuel; The flow rate of the carrier gas is set to a flow rate greater than the reference flow rate corresponding to the reduced supply amount of the solid fuel. Solid fuel crushing equipment.

6. The load is a mill differential pressure, which is the pressure difference between the inlet and the outlet of the housing; and Mill furnace differential pressure, which is the pressure difference between the outlet of the housing and the furnace of the boiler It is judged by at least one of the following:

6. The solid fuel pulverizer according to claim 5.

7. The solid fuel pulverizer according to claim 5, the boiler, which generates steam by burning the solid fuel pulverized by the solid fuel pulverizer in a combustion device; Equipped with Boiler equipment.

Images