JP6999349B2 - Control method of solid fuel crushing system, solid fuel crushing device and solid fuel crushing system - Google Patents

Description

The present invention relates to a solid fuel crushing system, a solid fuel crushing device and a method for controlling a solid fuel crushing system.

Conventionally, a crushing system including a plurality of crushers for crushing a carbon-containing solid fuel such as coal and a boiler to which pulverized coal produced by the plurality of crushers is supplied is known (see, for example, Patent Document 1). The crushing system disclosed in Patent Document 1 reduces the amount of coal supplied to the crusher determined to be in an abnormal state and increases the amount of coal supplied to other crushers, and the amount of pulverized coal produced in the entire crushing system. Is to keep it constant.

Japanese Unexamined Patent Publication No. 2013-176734

In a crushing system equipped with a plurality of crushers, it is desirable to set a lower limit for the operating load, which is the amount of solid fuel supplied to each crusher, in order to operate all the crushers stably. Then, for example, when the amount of coal supplied to the plurality of crushers decreases as the load (steam generation amount) of the boiler decreases and the operating load of the plurality of crushers falls below the lower limit, it becomes stable. Since crushing cannot be performed, it is necessary to stop and operate at least one of the plurality of crushers. However, when the crusher is stopped, it takes time to stop it, and when the load of the boiler increases, it takes time to restart the stopped crusher, so that the load on the boiler is increased. It takes time to change, and the operating efficiency of the crushing system is reduced.

The present disclosure has been made in view of such circumstances, and one of a plurality of solid fuel crushers is stopped by lowering the lower limit of the operating load for stable operation of the solid fuel crusher. It is an object of the present invention to provide a solid fuel crushing system, a solid fuel crushing device, and a control method thereof, which can reduce the frequency of fueling and suppress the decrease in operating efficiency.

In order to solve the above problems, the present disclosure adopts the following means.
The solid fuel crushing system according to one aspect of the present disclosure is a plurality of solid fuel crushing devices that crush solid fuel and supply it to a boiler, and the operation of the plurality of solid fuel crushing devices based on the target load of the boiler. The operating load of the generation unit that generates a control command for controlling the load and the operating load of the solid fuel crushing device operated by the control command generated by the generation unit are necessary for stable operation of the solid fuel crushing device. A determination unit that determines whether or not the operating load is below a predetermined lower limit value, and if the determination unit determines that the operating load does not fall below the predetermined lower limit value, the control command is issued. When the determination unit determines that the operating load is below the predetermined lower limit value by transmitting to each of the plurality of solid fuel crushing devices, the solid fuel crushing device may be applied to at least one of the plurality of solid fuel crushing devices. The solid fuel crushing device includes a transmission unit for transmitting a stop command for stopping the operation, a crushing table, a driving unit for generating a driving force for rotating the crushing table, and a fuel supply unit to the crushing table. A roller that crushes the supplied solid fuel between the crushing table and a classification unit that classifies the solid fuel crushed by the roller into fine powder fuel smaller than a predetermined particle size and carries it out from the solid fuel crusher. And a control unit that controls the rotation speed of the crushing table driven by the drive unit based on the control command transmitted from the transmission unit.

In a solid fuel crushing system including a plurality of solid fuel crushing devices, a lower limit of the operating load of each solid fuel crushing device is set in order to stably operate all the solid fuel crushing devices. If the operating load is below the lower limit, stable solid fuel crushing cannot be performed. Therefore, at least one of the plurality of solid fuel crushers is stopped, and the operating load of each solid fuel crusher is the lower limit. It is necessary to make it above. When the solid fuel crushing device is stopped, the time required for stopping and the time required for increasing the operating load and restarting are required, and the operating efficiency of the solid fuel crushing system is lowered.

The solid fuel crushing system according to one aspect of the present disclosure generates a control command for controlling the operating load of a plurality of solid fuel crushing devices based on the target load of the boiler, and the solid of each solid fuel crushing device based on the control command. It controls the number of revolutions of a crushing table (also called a rotary table) that crushes fuel powder between the rollers and the rollers. By reducing the number of revolutions of the crushing table, the decrease in the thickness of the solid fuel layer between the crushing table and the rollers is suppressed, and the occurrence of abnormal vibration of the solid fuel crushing device is suppressed, so stable crushing is performed. be able to.
Since the rotation speed of the crushing table is controlled based on the control command, the lower limit of the operating load for stable operation of the solid fuel crushing device is lower than when the rotation speed of the crushing table is kept constant. can do. That is, by lowering the lower limit of the operating load of the solid fuel crusher to the lowest possible operating load, it is possible to continue the operation with the required operating load without stopping a part of the plurality of solid fuel crushers. can. Therefore, the frequency of stopping any of the plurality of solid fuel crushing devices can be reduced as compared with the case where the rotation speed of the crushing table is kept constant, and the decrease in the operating efficiency of the solid fuel crushing system can be suppressed.

In the solid fuel crushing system according to one aspect of the present disclosure, the control unit controls the rotation speed of the crushing table driven by the drive unit based on the control command transmitted from the transmission unit. A control mode and a second control mode for maintaining the rotation speed of the crushing table at a constant rotation speed may be provided.
In the first control mode, since the rotation speed of the crushing table is controlled based on the control command, the lower limit of the operating load for stable operation of the solid fuel crushing device can be lowered. On the other hand, in the second control mode, since the rotation speed of the crushing table is maintained at a constant rotation speed, there is no response delay due to changing the rotation speed of the crushing table.

In the solid fuel crushing system according to one aspect of the present disclosure, the control unit executes the second control mode when starting or stopping the solid fuel crushing device, and after the start of the solid fuel crushing device is completed, the control unit executes the second control mode. The second control mode may be switched to the first control mode.
When starting or stopping the solid fuel crusher, it is not necessary to set the operating load of the solid fuel crusher to a low region, and when starting, the larger the fuel supply amount, the more the solid fuel layer between the crushing table and the roller. Since it is easy to secure the thickness, it is easy to start crushing, and when it is stopped, the time required to cool the crushing device can be shortened. Therefore, the second control mode for maintaining the rotation speed of the crushing table at a constant rotation is preferable. Is. On the other hand, after the start of the solid fuel crusher is completed, the lower limit of the operating load for stable operation of the solid fuel crusher can be lowered, so that the rotation speed of the crushing table is controlled based on the control command. The control mode of 1 is preferable.

The solid fuel crushing system according to one aspect of the present disclosure is a solid fuel crushing system including a plurality of solid fuel crushing devices that crush solid fuel and supply it to a boiler, and the plurality of solid fuel crushing systems are based on the target load of the boiler. Whether or not the operating load of the solid fuel crusher operated by the generation unit generated by the generation unit and the control command for controlling the operating load of the solid fuel crushing device is below a predetermined lower limit value. When the determination unit determines that the operating load does not fall below the predetermined lower limit value, the control command is transmitted to each of the plurality of solid fuel crushers, and the operating load is the operation load. When the determination unit determines that the value is below a predetermined lower limit, at least one of the plurality of solid fuel crushers is provided with a transmission unit for transmitting a stop command for stopping the operation of the solid fuel crusher. The solid fuel crushing device is a roller that crushes the crushing table, a driving unit that generates a driving force for rotating the crushing table, and the solid fuel supplied from the fuel supply unit to the crushing table. The solid fuel crushed by the roller is classified into fine powder fuel smaller than a predetermined particle size and carried out from the solid fuel crusher, and the drive is based on the control command transmitted from the transmission unit. A control unit for controlling the rotation speed of the crushing table driven by the unit is provided, and the control unit temporarily increases the rotation speed of the crushing table when the stop command is transmitted from the transmission unit. After that, the rotation of the crushing table may be stopped.
The transport gas supplied from the vertically lower side of the solid fuel crusher is blown up from the periphery of the crushing table toward the classification section, and the crushed fine fuel is transported to the classification section. By temporarily increasing the rotation speed of the crushing table when the stop command is transmitted, the solid fuel remaining on the crushing table is guided to the outer peripheral edge of the crushing table by centrifugal force and falls vertically downward from the outer peripheral edge. Can be made to. By guiding the solid fuel falling from the crushing table to the classification unit with the transport gas, the solid fuel remaining inside the solid fuel crushing device can be reduced when the solid fuel crushing device is stopped.

The solid fuel crushing apparatus according to one aspect of the present disclosure crushes solid fuel and supplies it to a boiler, a crushing table, a driving unit that generates a driving force for rotating the crushing table, and a crushing table from a fuel supply unit. Driven by a roller that crushes the solid fuel supplied to the crushing table between the crushing table, a classification unit that classifies the solid fuel crushed by the roller into fine powder fuel smaller than a predetermined particle size, and a driving unit. The control unit includes a control unit that controls the rotation speed of the crushing table, and the control unit temporarily increases the rotation speed of the crushing table when the solid fuel crushing device is stopped, and then the crushing table. Stop the rotation.

According to the solid fuel crusher according to one aspect of the present disclosure, the solid fuel remaining on the crushing table is discharged by centrifugal force by temporarily increasing the rotation speed of the crushing table when the solid fuel crushing device is stopped. It can be guided to the outer peripheral edge of the crushing table and dropped vertically downward from the outer peripheral edge. By guiding the solid fuel falling from the crushing table to the classification unit with the transport gas, the solid fuel remaining inside the solid fuel crushing device can be reduced when the solid fuel crushing device is stopped.

The control method of the solid fuel crushing system according to one aspect of the present disclosure is a control method of a solid fuel crushing system including a plurality of solid fuel crushing devices for crushing solid fuel and supplying the boiler to the boiler. A crushing table, a driving unit that generates a driving force for rotating the crushing table, a roller that crushes the solid fuel supplied from the fuel supply unit to the crushing table between the crushing table, and the roller. A classification unit for classifying the solid fuel crushed by the above into fine powder fuel having a particle size smaller than a predetermined particle size and carrying it out from the solid fuel crushing device is provided, and the plurality of solid fuel crushing devices are provided based on the target load of the boiler. In order for the operating load of the solid fuel crushing device operated by the generation step of generating the control command to control the operating load and the control command generated by the generation step to stably operate the solid fuel crushing device. A determination step for determining whether or not the required minimum value of the operating load is below a predetermined lower limit value, and a control command when the determination step determines that the operating load does not fall below the predetermined lower limit value. When the determination step determines that the operating load is below the predetermined lower limit value by transmitting to each of the plurality of solid fuel crushing devices, the solid fuel crushing device is used in at least one of the plurality of solid fuel crushing devices. It is provided with a transmission step of transmitting a stop command for stopping the operation of the fuel, and a control step of controlling the rotation speed of the crushing table driven by the drive unit based on the control command transmitted by the transmission step.

The control method of the solid fuel crushing system according to one aspect of the present disclosure generates a control command for controlling the operating load of a plurality of solid fuel crushing devices based on the target load of the boiler, and each solid fuel crushing is based on the control command. It controls the number of rotations of the grinding table of the device. Since the rotation speed of the crushing table is controlled based on the control command, the lower limit of the operating load for stable operation of the solid fuel crushing device is lowered as compared with the case where the rotation speed of the crushing table is kept constant. be able to. Therefore, the frequency of stopping any of the plurality of solid fuel crushing devices can be reduced as compared with the case where the rotation speed of the crushing table is kept constant, and the decrease in the operating efficiency of the solid fuel crushing system can be suppressed.

According to the present disclosure, the lower limit of the operating load for stable operation of the solid fuel crusher is lowered to reduce the frequency of stopping any of the plurality of solid fuel crushers, and the decrease in operating efficiency is suppressed. It is possible to provide a solid fuel crushing system, a solid fuel crushing device and a control method thereof.

It is a figure which shows the schematic structure of the boiler system of 1st Embodiment. It is a figure which shows the control configuration of the boiler system of 1st Embodiment. It is a figure which shows the relationship between the boiler load in the boiler system of 1st Embodiment, and the operation load of each solid fuel crushing apparatus. It is a figure which shows the rotation speed command value at the time of performing a stop operation of a solid fuel crusher. It is a flowchart which shows the process which the control part of the solid fuel crushing apparatus of 2nd Embodiment executes. It is a figure which shows the relationship between the boiler load in the boiler system of 2nd Embodiment, and the operation load of each solid fuel crushing apparatus.

Hereinafter, an embodiment of the boiler system (solid fuel crushing system) and the control method thereof according to the present disclosure will be described with reference to the drawings.
[First Embodiment]
Hereinafter, the first embodiment of the present disclosure will be described with reference to the drawings.
The boiler system (solid fuel crushing system) 1 shown in FIG. 1 includes a solid fuel crushing device 100, a boiler 200, and a control device 300. Although only one solid fuel crushing device 100 is shown in FIG. 1, in the present embodiment, for example, the boiler system 1 includes five solid fuel crushing devices 100. The number of the solid fuel crushing devices 100 included in the boiler system 1 is not limited to five, and may be any number of two or more.

The solid fuel crushing device 100 of the present embodiment is a device that crushes a carbon-containing solid fuel such as coal to generate fine pulverized fuel and supplies it to the burner portion (combustion device) 220 of the boiler 200. The solid fuel crushing device 100 of the present embodiment includes a mill 10, a coal feeder 20, a blower unit 30, a temperature detection unit 40, and a control unit 50.
In the present embodiment, "upper" means the direction of the vertically upper side, and "upper" such as the upper part and the upper surface means the part on the vertical upper side. Similarly, "bottom" indicates the part on the vertically lower side.

The mill 10 includes a housing 11, a crushing table 12, a roller 13, a drive unit 14, a drive shaft 15, a classification unit 16, a fuel supply unit 17, and a motor 18 that rotationally drives the classification unit 16. ..
The housing 11 is formed in a substantially cylindrical shape extending in the vertical direction, and is a housing that houses the crushing table 12, the rollers 13, the classification unit 16, and the fuel supply unit 17.

The crushing table 12 is a circular member in a plan view that rotates by a driving force transmitted from the drive unit 14 via the drive shaft 15, and solid fuel (for example, coal in this embodiment) is supplied from the fuel supply unit 17. The solid fuel powder is crushed between the roller 13 and the roller 13, and is also called a rotary table. Outlets (not shown) are provided at a plurality of locations on the outer peripheral side of the crushing table 12 to allow the primary air flowing from the primary air flow path 100a as a transport gas to flow out to the space above the crushing table 12 in the housing 11. ing. A vane (not shown) is installed above the air outlet to give a swirling force to the primary air blown out from the air outlet. The primary air to which the swirling force is applied by the vane becomes an air flow having a swirling velocity component, blows up the crushed solid fuel on the crushing table 12, and guides it to the upper classifying portion 16 in the housing 11. Of the crushed solid fuel mixed in the primary air, those having a particle size larger than the predetermined particle size are classified by the classification unit 16 or fall without reaching the classification unit 16 and returned to the upper surface of the crushing table 12.

The roller 13 is a rotating body that crushes the solid fuel supplied from the fuel supply unit 17 to the upper surface of the crushing table 12 with the crushing table 12. The 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. Although only one roller 13 is shown in FIG. 1, a plurality of rollers 13 are arranged at regular intervals in the circumferential direction so as to press the upper surface of the crushing table 12. For example, three rollers 13 are arranged on the outer peripheral portion with an angular interval of 120 °. In this case, the distance from the center of the crushing table 12 is substantially equidistant from the portion where the three rollers 13 are in contact with the upper surface of the crushing table 12 (the portion to be pressed).

The drive unit 14 is a device that transmits a driving force to the crushing table 12 via the drive shaft 15 and rotates the crushing table 12 around the central axis. The driving unit 14 generates a driving force for rotating the crushing table 12.
In the classification unit 16, the solid fuel crushed by the roller 13 is larger than a predetermined particle size (for example, 70 to 100 μm) (hereinafter, the crushed solid fuel exceeding the predetermined particle size is referred to as “coarse powder fuel”). It is a device for classifying crushed solid fuel having a predetermined particle size or less (hereinafter, crushed solid fuel having a predetermined particle size or less is referred to as "fine powder fuel"). The classification portion 16 has, for example, a truncated cone shape in outer shape, is attached to the upper part of the housing 11 along the cylindrical axis of the housing 11 having a substantially cylindrical shape, and is provided with a plurality of classification blades on the outer peripheral side. The classification unit 16 is given a driving force by the motor 18 and rotates about the cylindrical axis of the housing 11.

The crushed solid fuel mixed with the primary air that has reached the classification unit 16 puts the coarse fuel on the crushing table 12 due to the relative balance between the centrifugal force generated by the rotation of the classification blades and the centripetal force due to the flow of the primary air. The pulverized fuel (for example, pulverized coal fuel in the present embodiment) is guided from the housing 11 to the outlet 19 and carried out. The fine powder fuel classified by the classification unit 16 is mixed with the primary air and discharged from the outlet 19 to the supply flow path 100b. The pulverized fuel mixed with the primary air flowing out to the supply flow path 100b is supplied to the burner portion 220 of the boiler 200.

The fuel supply unit 17 is attached so as to penetrate the upper end of the housing 11 and supplies the solid fuel input from the upper portion to the substantially central region of the crushing table 12. The fuel supply unit 17 is supplied with solid fuel from the coal feeder 20.

The coal feeder 20 has a hopper 21, a transport unit 22, and a motor 23. The transport unit 22 transports the solid fuel discharged from the lower end of the hopper 21 by the driving force given from the motor 23, and guides the solid fuel to the fuel supply unit 17 of the mill 10 while controlling the supply amount of the solid fuel by the control unit 50. ..

The blower unit 30 is a device that dries the solid fuel crushed by the roller 13 and blows primary air as a transport gas for supplying the classifying unit 16 to the inside of the housing 11.
The blower unit 30 includes a hot gas blower 30a, a cold gas blower 30b, a hot gas damper 30c, and a cold gas damper 30d in order to adjust the primary air blown to the housing 11 to an appropriate temperature.

The hot gas blower 30a is a blower that blows heated primary air supplied via a heat exchanger (heater) such as an air preheater that uses the combustion gas of the boiler 200 as a heat source. A hot gas damper (first blower portion) 30c is provided on the downstream side of the hot gas blower 30a. The opening degree of the heat gas damper 30c is controlled by the control unit 50. The flow rate of the primary air blown by the hot gas blower 30a is determined by the opening degree of the hot gas damper 30c.

The cold gas blower 30b is a blower that blows primary air that is outside air at room temperature. A cold gas damper (second blower portion) 30d is provided on the downstream side of the cold gas blower 30b. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The flow rate of the primary air blown by the cold gas blower 30b is determined by the opening degree of the cold gas damper 30d. The flow rate of the primary air is the total flow rate of the primary air blown by the hot gas blower 30a and the flow rate of the primary air blown by the cold gas blower 30b, and the temperature of the primary air is the primary air blown by the hot gas blower 30a. It is determined by the mixing ratio of the primary air blown by the cold gas blower 30b, and is controlled by the control unit 50.

The temperature detection unit 40 is a sensor that detects the temperature of the outlet 19. The temperature detection unit 40 detects the temperature of the pulverized fuel discharged from the outlet 19 and outputs the temperature to the control unit 50.

The control unit 50 is a device that controls each unit of the solid fuel crushing device 100. The control unit 50 controls the rotation speed of the crushing table 12 by transmitting a drive instruction to the drive unit 14. Further, the control unit 50 can adjust the amount of solid fuel supplied by the transport unit 22 to the fuel supply unit 17 by transmitting the drive instruction to the motor 23 of the coal feeder 20. .. Further, the control unit 50 can control the opening degrees of the hot gas damper 30c and the cold gas damper 30d to control the flow rate and temperature of the primary air by transmitting the opening degree instruction to the blowing unit 30.

Next, the boiler 200 that burns using the fine fuel supplied from the solid fuel crusher 100 to generate steam will be described.
The boiler 200 includes a furnace 210 and a burner section 220.

The burner unit 220 is a device that burns the fine powder fuel by using the primary air containing the fine powder fuel supplied from the supply flow path 100b and the secondary air supplied from the heat exchanger (not shown). Combustion of the fine fuel is performed in the furnace 210, and the high-temperature combustion gas is discharged to the outside of the boiler 200 after passing through a heat exchanger (not shown) such as an evaporator, a superheater, and an economizer.

The combustion gas discharged from the boiler 200 is subjected to predetermined treatment by an environmental device such as a denitration device, and is sent to a heat exchanger (heater; not shown) such as an air preheater to exchange heat with the outside air. .. The outside air heated by heat exchange with the combustion gas in the heat exchanger is sent to the above-mentioned heat gas blower 30a. The water supply to each heat exchanger of the boiler 200 is heated in an economizer (not shown) and then further heated by an evaporator (not shown) and a superheater (not shown) to generate high temperature and high pressure steam. It is sent to a turbine (not shown) to rotate and drive a generator (not shown) to generate electricity.

Next, the control device 300 that controls the plurality of solid fuel crushing devices 100 will be described. The control device 300 is a device that generates a control command for controlling the operating load of the plurality of solid fuel crushing devices 100 based on the target load of the boiler 200, and controls each solid fuel crushing device 100. Further, the current load of the boiler 200 may be detected to improve the controllability, and in the present embodiment, the control device 300 is a plurality of solid fuel crushing devices based on the current load and the target load of the boiler 200. A device that generates a control command for controlling the operating load of 100 and controls each solid fuel crushing device 100 will be described.

FIG. 2 is a diagram showing a control configuration of the boiler system 1. The control device 300 includes a detection unit 310, a generation unit 320, a determination unit 330, and a transmission unit 340. Here, the detection unit 310, the generation unit 320, the determination unit 330, and the transmission unit 340 may each be configured by hardware including an arithmetic unit such as a CPU. Further, the detection unit 310, the generation unit 320, the determination unit 330, and the transmission unit 340 may be configured as software executed by a single or a plurality of arithmetic units.

The detection unit 310 may detect the load of the boiler 200 by the steam flow rate generated by the boiler 200, for example, based on the power generation amount of the generator connected to the steam turbine driven by the steam generated by the boiler 200. The load on the boiler 200 may be detected.

The generation unit 320 generates a control command for controlling the operating load of the plurality of solid fuel crushing devices 100 based on the load detected by the detection unit 310 and the target load of the boiler 200. Here, the target load of the boiler 200 is input to the control device 300 by, for example, an operator of the boiler system 1 or a computer in the central control room. The operating load of the solid fuel crusher 100 is a numerical value indicating, for example, the ratio of the target supply amount to the maximum supply amount of the pulverized fuel per unit time that can be supplied to the solid fuel crusher 100, for example, as a percentage.

In the present embodiment, the detection unit 310 detects the load of the boiler 200, and the generation unit 320 detects a plurality of solid fuel crushing devices 100 based on the load detected by the detection unit 310 and the target load of the boiler 200. Although a control command for controlling the operating load of the boiler 200 is generated, the generation unit 320 generates the operating load of a plurality of solid fuel crushing devices 100 based on the target load of the boiler 200 without detecting the load of the boiler 200. A control command to be controlled may be generated.

The determination unit 330 determines whether or not the operating load of the solid fuel crusher 100 operated by the control command generated by the generation unit 320 is less than a predetermined lower limit value. Here, the predetermined lower limit is the solid fuel crushing device 100 by suppressing abnormal vibration of the mill 10 generated by a decrease in the thickness of the solid fuel layer between the crushing table 12 and the roller 13. , The minimum value of the operating load required for stable operation. The predetermined lower limit value is determined by, for example, changing the operating load of the solid fuel crushing device 100 and measuring the amount of pulverized fuel supplied to the burner portion 220 of the boiler 200 in advance. The predetermined lower limit of the operating load of the solid fuel crusher 100 is, for example, 15% to 40%.

When the determination unit 330 determines that the operating load of the solid fuel crushing device 100 operated by the control command does not fall below a predetermined lower limit value, the transmission unit 340 issues a control command to each of the plurality of solid fuel crushing devices 100. It is transmitted to the control unit 50. Further, when the determination unit 330 determines that the operating load of the solid fuel crusher 100 operated by the control command is less than a predetermined lower limit value, the transmission unit 340 is assigned to at least one of the plurality of solid fuel crushers 100. A stop command for stopping the operation of the solid fuel crusher 100 is transmitted. The transmission unit 340 transmits a control command and a stop command to each solid fuel crushing device 100 via a signal line 350 that transmits and receives various signals to and from the plurality of solid fuel crushing devices 100.

When the determination unit 330 determines that the operating load of the solid fuel crushing device 100 operated by the control command is below a predetermined lower limit value, it is determined in advance which solid fuel crushing device 100 to transmit the stop command to. And. For example, when the determination unit 330 determines that the value is below a predetermined lower limit, a predetermined number of solid fuel crushers determined in advance based on a long-term operation plan including the maintenance period of the solid fuel crusher 100. It is predetermined that the stop command is transmitted to 100.

Further, when the stop command is transmitted to the predetermined solid fuel crushing device 100, the generation unit 320 regenerates the control command to be transmitted to the other solid fuel crushing device 100. The control command is regenerated because the initially generated control command is generated on the assumption that all five solid fuel crushing devices 100 are operated. The generation unit 320 regenerates the control command so as to be a control command according to the number of the solid fuel crushing devices 100 other than the solid fuel crushing device 100 that transmits the stop command.

The control unit 50 of each solid fuel crusher 100 controls the rotation speed of the crushing table 12 driven by the drive unit 14 based on the control command transmitted from the transmission unit 340. The control unit 50 stores in advance a table (not shown) in which the operating load of the solid fuel crushing device 100 indicated by the control command and the target rotation speed command value Rta for controlling the rotation speed of the crushing table 12 are associated with each other. It has a part (not shown). The control unit 50 reads the target rotation speed command value Rta corresponding to the control command from the storage unit, and transmits the target rotation speed command value Rta to the drive unit 14. The drive unit 14 controls the rotation speed of the crushing table 12 so that the rotation speed corresponds to the target rotation speed command value Rta transmitted from the control unit 50. For example, the rotation speed of the drive motor (not shown) of the drive unit 14 may be controlled by an inverter.

Further, in the target rotation speed command value Rta stored in the storage unit, for example, the thickness of the solid fuel layer between the crushing table 12 and the roller 13 changes with respect to the operating load according to the type of solid fuel. The number of rotations of the crushing table 12 capable of stably operating the solid fuel crushing device 100 without the occurrence of abnormal vibration of the mill 10 caused by the decrease in the number of the crushing table 12 may be acquired in advance and recorded and stored. ..

Further, the control unit 50 of each solid fuel crusher 100 supplies the solid fuel supplied from the coal feeder 20 to the mill 10 through the fuel supply unit 17 according to the operating load of the solid fuel crusher 100 indicated by the control command. Control the amount. Further, the control unit 50 of each solid fuel crushing device 100 controls the flow rate of the primary air blown by the blowing unit 30 according to the operating load of the solid fuel crushing device 100 indicated by the control command. Further, the control unit 50 of each solid fuel crushing device 100 controls the rotation speed of the classification unit 16 according to the operating load of the solid fuel crushing device 100 indicated by the control command.

As described above, the control unit 50 of each solid fuel crusher 100 supplies the solid fuel from the coal feeder 20 and the rotation speed of the crushing table 12 according to the operating load of the solid fuel crusher 100 indicated by the control command. The amount, the flow rate of the primary air, and the rotation speed of the classification unit 16 are controlled respectively. Since the same control command is transmitted to each solid fuel crusher 100, each solid fuel crusher 100 operates in the same manner.

Next, an example of the operation executed by the control device 300 transmitting the control command and the stop command to the control unit 50 of each solid fuel crushing device 100 will be described. FIG. 3 is a diagram showing the relationship between the boiler load in the boiler system 1 of the present embodiment and the operating load of each solid fuel crushing device 100. The solid fuel crushing device 100 is composed of, for example, five units, the predetermined lower limit of the operating load of each solid fuel crushing device 100 is MLmin1, and the operating load for the maximum supply amount of the pulverized fuel is MLmax. The solid line shown in FIG. 3 is the operating load of each solid fuel crushing device 100 operated based on the control command and the stop command according to the present embodiment.

When the load of the boiler 200 detected by the detection unit 310 is BL2 or more, the operating load of each solid fuel crushing device 100 operated by the control command generated by the generation unit 320 is MLmin1 or more. In this case, the determination unit 330 determines that the operating load of each solid fuel crushing device 100 does not fall below the predetermined lower limit value of MLmin1, and transmits a control command to each of the five solid fuel crushing devices 100. The five solid fuel crushing devices 100 to which the control command is transmitted are operated with an operating load according to the control command. As will be described later, by lowering MLmin1, which is a predetermined lower limit of the operating load of each solid fuel crushing device 100, to the lowest possible operating load, the solid fuel crushing device 100 responds to the control command with five units. The operation can be continued with the operating load.

When the load of the boiler 200 detected by the detection unit 310 is lower than BL2, the operating load of each solid fuel crushing device 100 operated by the control command generated by the generation unit 320 is lower than the predetermined lower limit value of MLmin1. In this case, the determination unit 330 determines that the operating load of each solid fuel crushing device 100 is less than MLmin1, and for example, the transmission unit 340 transmits a stop command to three predetermined solid fuel crushing devices 100. The three solid fuel crushing devices 100 to which the stop command is transmitted execute the stop operation described later. Since the stop operation requires several tens of minutes, such as discharging the residual coal inside the solid fuel crusher 100, a load holding time that does not change the load of the boiler 200 is required during that time. Further, the other two predetermined solid fuel crushing devices 100 continue to operate under the operating load described later.

When the transmission unit 340 transmits three stop commands, the generation unit 320 receives a control command according to the other two solid fuel crushing devices 100 except for the three solid fuel crushing devices 100 that transmit the stop command. Regenerate the control command so that As shown in FIG. 3, the control command generated by the generation unit 320 is, for example, MLmax, which is the upper limit of the operating load of each solid fuel crusher 100 in the boiler load BL2. The MLmax is 100% or less of the operating load, and it is more preferable to have a margin of the operating load from 100%.

The reason why each solid fuel crushing device 100 operated by the control command generated by the generator 320 has increased significantly from MLmin1 to MLmax is that the number of solid fuel crushing devices 100 that supply pulverized fuel to the boiler 200 is five. This is because the number has decreased from two to two. Since the number of solid fuel crushing devices 100 in the operating state has decreased, the operating load of each solid fuel crushing device 100 has increased. Here, in the boiler load BL2, the operating load of each solid fuel crushing device 100 is set to MLmax, which is the upper limit, but the operating load is not limited to MLmax due to the crushing capacity of the solid fuel crushing device 100, etc. It should be.

When the load of the boiler 200 detected by the detection unit 310 is BL1 or more and less than BL2, here, two solid fuel crushing devices 100 operate with an operating load according to the control command. The three solid fuel crushers 100 maintain a stopped state. When the load of the boiler 200 detected by the detection unit 310 is lower than BL1, the transmission unit 340 transmits a stop command to the two solid fuel crushing devices 100 in the operating state. The two solid fuel crushing devices 100 to which the stop command is transmitted execute the stop operation described later. When the load of the boiler 200 is lower than BL1, all the solid fuel crushing devices 100 are stopped and the boiler 200 is stopped. If necessary, when the boiler 200 is operated with a load less than BL1, the boiler 200 may be operated by an auxiliary fuel burner (not shown).

Next, a comparative example of this embodiment will be described. The broken line shown in FIG. 3 shows a comparative example of the present embodiment. In the comparative example of this embodiment, the control unit 50 of each solid fuel crushing device 100 maintains the rotation speed of the crushing table 12 at a constant rotation speed regardless of the control command transmitted from the transmission unit 340. In the comparative example, when the operating load of each solid fuel crushing device 100 reaches MLmin2 which is larger than MLmin1, for example, a stop command is transmitted to two predetermined solid fuel crushing devices 100. The other three predetermined solid fuel crushing devices 100 continue to operate under the operating load described later.

In order to maintain the rotation speed of the crushing table 12 at a constant rotation speed, a stop command is transmitted when the operating load of each solid fuel crushing device 100 reaches MLmin2 which is larger than MLmin1. This is because when the rotation speed of the crushing table 12 is maintained at a constant rotation speed, the rotation speed of the crushing table 12 is controlled according to the operating load, and when the operating load is higher, the crushing table 12 and the crushing table 12 This is because the solid fuel crushing device 100 cannot be operated stably due to abnormal vibration of the mill 10 generated by a decrease in the thickness of the solid fuel layer between the rollers 13 and the like.

When maintaining the rotation speed of the crushing table 12 at a constant rotation speed, it is necessary to reduce the supply amount of solid fuel from the coal feeder 20, the flow rate of the primary air, and the rotation speed of the classification unit 16 in order to reduce the operating load. be. However, if these parameters are lowered so as to be lower than MLmin2 while the rotation speed of the crushing table 12 is maintained at a constant rotation speed, the solid fuel crushing device 100 is stably operated due to the occurrence of abnormal vibration of the mill 10. You will not be able to.

As shown in FIG. 3, in the present embodiment, when the boiler load is BL2 or more, for example, five solid fuel crushers 100 can be maintained in an operating state, but in the comparative example, the boiler load is lower than BL3, which is higher than BL2. Until, for example, it is necessary to stop two predetermined solid fuel crushing devices 100, and the range in which the solid fuel crushing device 100 can be operated by five units is narrowed in the range from BL2 to BL3.

Therefore, since the present embodiment has a wider range of boiler load that can maintain the five solid fuel crushing devices 100 in the operating state, the frequency of stopping any of the plurality of solid fuel crushing devices 100 is reduced, and the solid fuel is reduced. It is possible to save time and effort required for stopping and restarting the crushing device 100. Therefore, it is possible to reduce the occurrence of the load holding time that does not change the load of the boiler 200 that occurs during the time of stopping or restarting the solid fuel crushing device 100, and it is possible to suppress the decrease in operating efficiency.

Next, the stop operation executed by the solid fuel crusher 100 to which the stop command is transmitted from the transmission unit 340 will be described.
FIG. 4 is a diagram showing a rotation speed command value of the crushing table 12 when the solid fuel crushing device 100 executes a stop operation. The time t1 indicates the timing at which the stop command is transmitted from the transmission unit 340 to the solid fuel crusher 100. In the period until time t1, the rotation speed of the crushing table 12 of the solid fuel crushing device 100 is gradually decreased. Therefore, the target rotation speed command value Rta of the crushing table 12 gradually decreases with the passage of time.

The control unit 50 of the solid fuel crushing device 100 to which the stop command is transmitted from the transmission unit 340 maintains the target rotation speed command value Rta1 of the crushing table 12 at the time t1 for a certain period of time until the time t2. From time t1 to time t2, the control unit 50 increases the opening degree of the cold gas damper 30d while closing the hot gas damper 30c. Further, the control unit 50 stops the supply of solid fuel from the coal feeder 20 to the mill 10. By this operation, the temperature inside the mill 10 is lowered, and the solid fuel existing inside the mill 10 is reduced. The time from time t1 to time t2 requires, for example, 10 to 30 minutes.

When the time t2 is reached, the control unit 50 of the solid fuel crushing device 100 increases the target rotation speed command value Rta of the crushing table 12 from Rta1 to Rta2 to temporarily increase the rotation speed of the crushing table 12. The solid fuel remaining on the crushing table 12 is guided to the outer peripheral end of the crushing table 12 by centrifugal force, dropped downward from the outer peripheral end, and conveyed by the primary air blown up from the periphery of the crushing table 12 to be guided to the classification section. This makes it possible to reduce the amount of solid fuel remaining inside the solid fuel crushing device 100 when the device is stopped.

The target rotation speed command value Rta2 of the crushing table 12 is set to be equal to or less than the target rotation speed command value Rta of the crushing table 12 set when the operating load is MLmax or the operating load is 100%, depending on the type of solid fuel. After that, the target rotation speed command value Rta of the crushing table 12 is gradually reduced so that the rotation speed of the crushing table 12 becomes zero at time t3. The time from time t2 to time t3 is, for example, 5 minutes or more and 30 in order to guide the solid fuel remaining on the crushing table 12 to the outer peripheral edge of the crushing table 12 by centrifugal force and reduce the remaining solid fuel. The time is preferably within minutes.

The operation and effect of the boiler system 1 of the present embodiment described above will be described.
The boiler system 1 of the present embodiment generates a control command for controlling the operating load of a plurality of solid fuel crushing devices 100 based on the load detected by the detection unit 310 and the target load of the boiler 200, and is based on the control command. The rotation speed of the crushing table 12 of each solid fuel crushing device 100 is controlled. Since the rotation speed of the crushing table 12 is controlled based on the control command, the solid fuel crushing device 100 is operated more stably than the lower limit value MLmin2 of the operating load when the rotation speed of the crushing table 12 is kept constant. The lower limit value MLmin1 of the operating load for this purpose can be lowered. Therefore, the frequency of stopping any one of the plurality of solid fuel crushing devices 100 is reduced as compared with the case where the rotation speed of the crushing table 12 is kept constant, and it occurs during the time of stopping or restarting the solid fuel crushing device 100. It is possible to reduce the occurrence of a load holding time that does not change the load of the boiler 200, and it is possible to suppress a decrease in the operating efficiency of the boiler system 1.

Further, according to the boiler system 1 of the present embodiment, the solid fuel remaining on the crushing table 12 is crushed by centrifugal force by temporarily increasing the rotation speed of the crushing table 12 when the stop command is transmitted. The solid fuel dropped from the crushing table 12 is dropped downward from the outer peripheral edge of the table 12 and conveyed by the primary air blown up from the periphery of the crushing table 12 to be guided to the classification unit 16 into the inside of the solid fuel crushing device 100. The residual solid fuel can be reduced.

Therefore, when the solid fuel crushing device 100 is stopped, the risk of ignition due to the solid fuel remaining in the device can be reduced. Further, since the time required to carry out the remaining solid fuel can be shortened, the time required to stop the solid fuel crushing device 100 can be shortened. Therefore, it is possible to further reduce the occurrence of the load holding time that does not change the load of the boiler 200 that occurs during the downtime of the solid fuel crushing device 100, and further suppress the decrease in the operating efficiency of the boiler system 1. can.

[Second Embodiment]
Next, a second embodiment of the present disclosure will be described.
The second embodiment is a modification of the first embodiment, and is the same as the first embodiment except for the cases described below, and the description thereof will be omitted below. In this embodiment, the control unit 50 of each solid fuel crushing device 100 has a first control mode for controlling the rotation speed of the crushing table 12 and a second control for maintaining the rotation speed of the crushing table 12 at a constant rotation speed. It has a mode.

FIG. 5 is a flowchart showing a process executed by the control unit 50 of the solid fuel crusher 100 of the second embodiment.
As shown in FIG. 5, in the control unit 50 of the solid fuel crushing device 100 of the present embodiment, when a control command is transmitted from the transmission unit 340, whether or not the first control mode is designated in step S501. Is determined. The control unit 50 executes the first control mode in step S502 when it is determined to be YES, and executes the second control mode in step S503 when it is determined to be NO.

The first control mode is a mode for controlling the rotation speed of the crushing table 12 driven by the drive unit 14 based on the control command transmitted from the transmission unit 340. The solid line shown in FIG. 6 shows the operating load of each solid fuel crushing device 100 operated in the first control mode. The operation executed by the control unit 50 in the first control mode is the same as the operation executed by the control unit 50 in the first embodiment. Therefore, the description below will be omitted.

The second control mode is a mode in which the rotation speed of the crushing table 12 is maintained at a constant rotation speed regardless of the control command transmitted from the transmission unit 340. The broken line shown in FIG. 6 illustrates a case where the rotation speed of the crushing table 12 is set to a constant rotation speed at the same rotation speed as when the operating load is MLmax. The operating load of each solid fuel crusher 100 operated in the second control mode is shown. The operation executed by the control unit 50 in the second control mode is the same as the operation of the comparative example of the first embodiment. Therefore, the description below will be omitted.

The control unit 50 designates a second control mode, for example, when the solid fuel crushing device 100 is in a state from a stopped state to a start state. Further, the control unit 50 designates a second control mode when the solid fuel crushing device 100 is in the stop operation of shifting from the operating state to the stopped state. In this way, when starting or stopping the solid fuel crushing device, the rotation speed of the crushing table 12 is controlled by stabilizing the operation and control without changing the rotation speed of the crushing table 12. This is because the second control mode in which the rotation speed of the crushing table 12 is maintained at a constant rotation speed is preferable for stabilization.

For example, the control unit 50 designates the first control mode after the start-up of the solid fuel crushing device 100 is completed, and switches the second control mode to the first control mode. By switching to the first control mode after the start-up is completed, the frequency of stopping any one of the plurality of solid fuel crushers 100 is reduced as in the first embodiment, and the deterioration of the operating efficiency of the boiler system 1 is suppressed. Can be done.

In step S504, the control unit 50 determines whether or not the stop command has been transmitted from the transmission unit 340. If YES, the process proceeds to step S505, and if NO, step S501 is executed again.
In step S505, the control unit 50 executes a stop operation for stopping the solid fuel crushing device 100. This stop operation is the same as the stop operation described in the first embodiment.

According to the present embodiment described above, in the first control mode, the rotation speed of the crushing table 12 is controlled based on the control command, so that the operating load for stably operating the solid fuel crushing device 100 The lower limit of can be lowered. On the other hand, in the second control mode, since the rotation speed of the crushing table 12 is maintained at a constant rotation speed, there is no response delay due to changing the rotation speed of the crushing table 12.

1 Boiler system (solid fuel crushing system)
10 Mill 11 Housing 12 Crushing table 13 Roller 14 Drive unit 15 Drive shaft 16 Classification unit 17 Fuel supply unit 18 Motor 19 Outlet 20 Coal supply machine 30 Blower unit 40 Temperature detection unit 50 Control unit 100 Solid fuel crusher 200 Boiler 210 Fire furnace 220 Burner part (combustion device)
300 Control device 310 Detection unit 320 Generation unit 330 Judgment unit 340 Transmission unit

Claims (7)

A solid fuel crushing system equipped with multiple solid fuel crushing devices that crush solid fuel and supply it to the boiler.
A generation unit that generates a control command for controlling the operating load of the plurality of solid fuel crushers based on the target load of the boiler.
A predetermined lower limit value in which the operating load of the solid fuel crushing device operated by the control command generated by the generation unit is the minimum value of the operating load required for stable operation of the solid fuel crushing device. Judgment unit that determines whether or not it is below
When the determination unit determines that the operating load does not fall below the predetermined lower limit value, the control command is transmitted to each of the plurality of solid fuel crushers, and when the operating load falls below the predetermined lower limit value. When the determination unit determines, at least one of the plurality of solid fuel crushers is provided with a transmission unit for transmitting a stop command for stopping the operation of the solid fuel crusher.
The solid fuel crusher is
With a crushing table,
A drive unit that generates a driving force to rotate the crushing table,
A roller that crushes the solid fuel supplied from the fuel supply unit to the crushing table between the crushing table and the roller.
A classifying unit that classifies the solid fuel crushed by the roller into fine powder fuel having a particle size smaller than a predetermined particle size and carries it out from the solid fuel crushing device.
A solid fuel crushing system including a control unit for controlling the rotation speed of the crushing table driven by the drive unit based on the control command transmitted from the transmission unit. The control unit has a first control mode for controlling the rotation speed of the crushing table driven by the driving unit based on the control command transmitted from the transmission unit, and a constant rotation of the rotation speed of the crushing table. The solid fuel milling system according to claim 1, comprising a second control mode of maintaining a number. The control unit executes the second control mode when starting or stopping the solid fuel crushing device, and after the start of the solid fuel crushing device is completed, the second control mode is changed to the first control mode. The solid fuel crushing system according to claim 2 to be switched. The predetermined lower limit is set according to claim 1 so that the ratio of the target supply amount to the maximum supply amount of the solid fuel per unit time that can be supplied to the solid fuel crusher is 15% to 40%. The solid fuel crushing system according to any one of claims 3. A solid fuel crushing system equipped with multiple solid fuel crushing devices that crush solid fuel and supply it to the boiler.
A generation unit that generates a control command for controlling the operating load of the plurality of solid fuel crushers based on the target load of the boiler.
A determination unit for determining whether or not the operating load of the solid fuel crusher operated by the control command generated by the generation unit is below a predetermined lower limit value.
When the determination unit determines that the operating load does not fall below the predetermined lower limit value, the control command is transmitted to each of the plurality of solid fuel crushers, and when the operating load falls below the predetermined lower limit value. When the determination unit determines, at least one of the plurality of solid fuel crushers is provided with a transmission unit for transmitting a stop command for stopping the operation of the solid fuel crusher.
The solid fuel crusher is
With a crushing table,
A drive unit that generates a driving force to rotate the crushing table,
A roller that crushes the solid fuel supplied from the fuel supply unit to the crushing table between the crushing table and the roller.
A classifying unit that classifies the solid fuel crushed by the roller into fine powder fuel having a particle size smaller than a predetermined particle size and carries it out from the solid fuel crushing device.
A control unit for controlling the rotation speed of the crushing table driven by the drive unit based on the control command transmitted from the transmission unit is provided.
The control unit is a solid fuel crushing system that temporarily increases the rotation speed of the crushing table and then stops the rotation of the crushing table when the stop command is transmitted from the transmission unit. A control method for a solid fuel crushing system equipped with multiple solid fuel crushing devices that crush solid fuel and supply it to the boiler.
The solid fuel crushing device crushes the solid fuel supplied from the fuel supply unit to the crushing table between the crushing table, a driving unit that generates a driving force for rotating the crushing table, and the crushing table. It is provided with a roller and a classification unit for classifying the solid fuel crushed by the roller into fine powder fuel smaller than a predetermined particle size and carrying it out from the solid fuel crusher.
A generation step of generating a control command for controlling the operating load of the plurality of solid fuel crushers based on the target load of the boiler.
A predetermined lower limit value in which the operating load of the solid fuel crushing device operated by the control command generated by the generation step is the minimum value of the operating load required for stable operation of the solid fuel crushing device. Judgment process to determine whether it is below
When the determination step determines that the operating load does not fall below the predetermined lower limit value, the control command is transmitted to each of the plurality of solid fuel crushers, and when the operating load falls below the predetermined lower limit value. When the determination step determines, a transmission step of transmitting a stop command for stopping the operation of the solid fuel crusher to at least one of the plurality of solid fuel crushers, and a transmission step.
A control method for a solid fuel crushing system, comprising a control step of controlling the rotation speed of the crushing table driven by the driving unit based on the control command transmitted by the transmission step. A control method for a solid fuel crushing system equipped with multiple solid fuel crushing devices that crush solid fuel and supply it to the boiler.
The solid fuel crushing device crushes the solid fuel supplied from the fuel supply unit to the crushing table between the crushing table, a driving unit that generates a driving force for rotating the crushing table, and the crushing table. It is provided with a roller and a classification unit for classifying the solid fuel crushed by the roller into fine powder fuel smaller than a predetermined particle size and carrying it out from the solid fuel crusher.
A generation step of generating a control command for controlling the operating load of the plurality of solid fuel crushers based on the target load of the boiler.
A determination step of determining whether or not the operating load of the solid fuel crusher operated by the control command generated by the generation step is below a predetermined lower limit value.
When the determination step determines that the operating load does not fall below the predetermined lower limit value, the control command is transmitted to each of the plurality of solid fuel crushers, and when the operating load falls below the predetermined lower limit value. When the determination step determines, a transmission step of transmitting a stop command for stopping the operation of the solid fuel crusher to at least one of the plurality of solid fuel crushers, and a transmission step.
A control step for controlling the rotation speed of the crushing table driven by the drive unit based on the control command transmitted by the transmission step is provided.
The control step is a control method for a solid fuel crushing system in which the rotation speed of the crushing table is temporarily increased and then the rotation of the crushing table is stopped when the stop command is transmitted by the transmission step.

Images