JP2020116537A - Solid fuel crushing device and electric power generating plant comprising the same as well as control method for solid fuel crushing device - Google Patents

Abstract

To provide a solid fuel crushing device that can detect deterioration in classification performance.SOLUTION: A mill 10 comprises: a rotary table 12; a roller 13 that crushes solid fuel between the rotary table 12 and the roller; a rotary classifier 16, positioned in a vertical direction above the rotary table 12, which classifies the crushed fuel crushed by the roller 13; and powder layer height measurement means 52 that measures a height H1 of a powder layer made of the crushed fuel formed on the rotary table 12. The powder layer height measurement means 52 comprises manometers 53 and detection tubes 54 connected to the manometers 53.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a solid fuel crushing apparatus, a power plant including the same, and a method for controlling the solid fuel crushing apparatus.

Conventionally, a solid fuel such as coal or biomass fuel is pulverized by a pulverizer (mill) into a fine powder having a particle size smaller than a predetermined particle size and supplied to a combustion device. The mill grinds solid fuel such as coal and biomass fuel put into the rotary table by biting between the rotary table and the rollers, and pulverized by carrier gas supplied from the outer periphery of the rotary table into fine powder. The separated fuel is sorted by a classifier into small-sized particles, conveyed to a boiler, and burned in a combustion device. In a thermal power plant, steam is generated by heat exchange with combustion gas generated by combustion in a boiler, and the turbine is driven by the steam to generate power.

The pulverized solid fuel pulverized by the mill (fuel after pulverization) is classified into fine particles and coarse particles by a rotary classifier installed on the upper part of the mill. The fine fuel particles, which are fine particles, pass between the blades of the rotary classifier and are sent to the combustion device, which is a post-process, and the coarse fuel particles, which are coarse particles, collide with the blades of the rotary classifier and fall to the rotary table. Will be crushed again. Therefore, due to the classification performance of the rotary classifier, the circulated amount of the pulverized solid fuel circulating between the rotary classifier and the rotary table inside the mill increases or decreases.

In such a mill, the pressure difference between the upstream side of the carrier gas supplied into the mill and the inside of the pulverizer is used to grasp the internal state of the pulverized fuel during operation in the mill. The mill differential pressure is measured (see Patent Document 1).

JP-A-8-141420

In recent years, the use of renewable energy has been promoted, and there is an increasing need to pulverize biomass fuel using a conventional coal mill. However, during mill operation, the fuel stays directly above the rotary table after pulverization and forms a powder layer with a high powder concentration.However, since biomass fuel has lighter coarse particles than coal, coarse particles float up and the rotary table Even coarse particles in the vicinity can be easily transported to the vicinity of the rotary classifier by the carrier gas, and the coarse particles may enter the rotary classifier. When coarse particles of biomass fuel are conveyed into the rotary classifier, the finished particle size of the fine-grained fuel discharged from the mill to the combustion burner decreases, which may reduce the combustion performance of the combustion burner. There is.

At the measuring point for detecting the mill differential pressure as shown in Patent Document 1, it is difficult to detect the height of the powder layer on the rotary table, and it is not possible to prevent deterioration of the classification performance. ..

The present invention has been made in view of such circumstances, and provides a solid fuel crushing device capable of suppressing a decrease in classification performance, a power plant including the same, and a control method of the solid fuel crushing device. The purpose is to

A solid fuel crushing apparatus according to an aspect of the present invention includes a rotary table, a crushing roller that crushes solid fuel between the rotary table, and a vertical position above the rotary table, and the crushing roller crushes the solid fuel. A rotary classifier for classifying the pulverized fuel, and a powder layer height measuring means for measuring the powder layer height of the pulverized fuel formed on the rotary table are provided.

The pulverized solid fuel pulverized by the rotary table and the pulverizing roller becomes pulverized fuel and forms a powder layer having a predetermined height on the rotary table. The powder layer refers to a region in which the pulverized fuel blown up by the carrier gas stays at a higher concentration than others. Further, the powder layer height indicates a position vertically upward with the reference position as the crushing surface of the rotary table. When the powder bed height rises and approaches the vertical rotary classifier, some coarse-grained fuel is not classified by the rotary classifier and mixed with the fine-grained fuel from the solid fuel grinder into the burner section. Since it is supplied, the combustion performance of the burner part may deteriorate. Therefore, the powder layer height measuring means is used to measure the powder layer height. As a result, the height of the powder layer can be adjusted appropriately and the deterioration of the classification performance in the solid fuel pulverizer can be suppressed.
As the solid fuel, for example, biomass fuel or a mixed fuel of biomass fuel and coal is used.

Further, in the solid fuel crushing apparatus according to one aspect of the present invention, the powder bed height measuring means includes a plurality of pressures provided at different height positions between the rotary table and the rotary classifier. It has a detector.

A plurality of pressure detectors are provided at different height positions between the rotary table and the rotary classifier. Thereby, the pressure distribution in the height direction can be obtained. Since the powder layer has a higher density than gas layers other than the powder layer (for example, the air layer), the pressure loss is large. Therefore, if the pressure distribution in the height direction is obtained, it can be seen that the height position where the change in pressure loss is large corresponds to the powder layer height.

Furthermore, in the solid fuel crushing apparatus according to one aspect of the present invention, the plurality of pressure detection units are provided at different positions in the circumferential direction of the rotary table.

The pressure detector is provided at different positions in the circumferential direction of the rotary table. Accordingly, the pressure detecting portions can be dispersedly arranged at different height positions in the circumferential direction, so that an installation space can be secured when arranging the plurality of pressure detecting portions.

Furthermore, in the solid fuel crushing apparatus according to one aspect of the present invention, a control unit that obtains a detection signal of the powder layer height measuring means is provided, and the control unit is based on the detection signal. Change the operating conditions to reduce power consumption.

The control unit changes the operating condition so as to reduce the powder layer height based on the detection signal of the powder layer height measuring means. As a result, by realizing an appropriate powder layer height, desired classification performance can be maintained.
This change in the operating condition can be used during the test operation of the solid fuel pulverizer or during the operation.

Further, in the solid fuel crushing apparatus according to one aspect of the present invention, the control unit changes the operating condition so as to reduce the solid fuel supply amount supplied to the rotary table.

The powder bed height can be reduced by reducing the supply amount of the solid fuel supplied onto the rotary table.

Further, in the solid fuel crushing apparatus according to one aspect of the present invention, the control unit changes the operating condition so as to increase the flow rate of the carrier gas flowing from the rotary table toward the rotary classifier.

The powder bed height can be reduced by increasing the flow rate of the carrier gas flowing from the rotary table to the rotary classifier.
The flow rate of the carrier gas may be increased at the same time as the decrease of the solid fuel supply amount, or may be performed after the decrease of the solid fuel supply amount. If the flow rate of the carrier gas is increased after the supply amount of the solid fuel is decreased, the carrier gas is increased and supplied after the amount of fuel after pulverization accumulated inside is decreased. It is possible to suppress and suppress the auxiliary machine power required for the blower for supplying the carrier gas.

Further, a power plant according to an aspect of the present invention, a solid fuel crushing device according to any of the above, a boiler that burns the crushed fuel crushed by the solid fuel crushing device to generate steam And a power generation unit that generates electric power using the steam generated by the boiler.

Further, in the method for controlling a solid fuel crushing apparatus according to one aspect of the present invention, a rotary table, a crushing roller for crushing solid fuel between the rotary table, and a crusher located vertically above the rotary table, A rotary fuel classifier for classifying the crushed fuel crushed by rollers, and a method for controlling a solid fuel crushing device, comprising: controlling a powder layer height of the crushed fuel formed on the rotary table. measure.

Since the powder layer height measuring means measures the powder layer height on the rotary table, it is possible to adjust the proper powder layer height and suppress the deterioration of the classification performance.

It is a schematic structure figure showing a power plant concerning one embodiment of the present invention. It is a longitudinal cross-sectional view showing a main part of the mill of FIG. It is a cross-sectional view of the mill showing the arrangement of the detection tube. It is a longitudinal cross-sectional view of a main part of the mill showing a detection pipe to which a purge pipe is connected. It is a schematic block diagram which showed arrangement|positioning of a manometer. It is a graph which showed an example of the measurement result of Drawing 5A. 6 is a graph showing a powder layer height with respect to a fuel supply amount. It is a graph which showed the powder layer height with respect to a carrier gas flow rate. It is the flowchart which showed the change of the operating condition of a mill. It is a schematic block diagram which showed arrangement|positioning of the manometer which concerns on a modification. It is the graph which showed an example of the measurement result of FIG. 8A.

An embodiment of the present invention will be described below with reference to the drawings.

<Overall structure of power generation plant 1>
The power plant 1 according to the present embodiment includes a solid fuel grinding system 100 and a boiler 200.
The solid fuel crushing system 100 is a device that crushes solid fuel such as biomass fuel to generate fine fuel particles and supply the fine fuel particles to the burner unit 220 of the boiler 200. The power plant 1 includes one solid fuel crushing system 100, but as a system including a plurality of solid fuel crushing systems 100 corresponding to the burner units 220 of one boiler 200, respectively. Good. Further, although the biomass fuel is mainly used in the power generation plant 1 of the present embodiment, it is also possible to co-firing coal and biomass fuel.

The solid fuel crushing system 100 includes a mill (solid fuel crushing device) 10, a coal feeder 20, a blower 30, a state detector 40, and a controller 50.
In the present embodiment, “upper” means a direction on the vertically upper side, and “upper” such as an upper portion and a top surface means a portion on the vertically upper side. Similarly, "lower" means a portion on the vertically lower side.

Biomass fuel is an organic resource derived from renewable organisms, such as thinned wood, waste timber, driftwood, grass, waste, sludge, tires and recycled fuel (pellets and chips) made from these materials. Yes, and is not limited to those presented here. The size of the pellet is, for example, about 6 to 8 mm in diameter, and the length is about 40 mm or less. Biomass fuel is carbon-neutral that does not emit carbon dioxide, which is a global warming gas, because it takes in carbon dioxide during the growth process of biomass. Therefore, various uses thereof have been studied.

The mill 10 includes a housing 11, a rotary table 12, rollers 13 (crushing rollers), a drive unit 14, a classifier (rotary classifier) 16, a fuel supply unit 17, and a classifier (rotary classifier). ) 16 is rotationally driven.

The housing 11 is a casing that is formed in a cylindrical shape that extends in the vertical direction and that houses the rotary table 12, the rollers 13, the classifier 16, and the fuel supply unit 17. The fuel supply unit 17 is attached to the central portion of the ceiling portion 42 of the housing 11. The fuel supply unit 17 supplies the solid fuel guided from the bunker 21 into the housing 11, is arranged vertically in the center of the housing 11, and has a lower end extending into the housing 11. ..

The drive unit 14 is installed near the bottom surface 41 of the housing 11, and the rotary table 12 that is rotated by the drive force transmitted from the drive unit 14 is rotatably arranged. The drive unit 14 is controlled by the control unit 50.

The turntable 12 is a circular member in plan view, and is arranged so that the lower ends of the fuel supply units 17 face each other. The upper surface of the rotary table 12 may have, for example, a slanted shape such that the central portion is low and the height is high toward the outside, and the outer peripheral portion is bent upward. The fuel supply unit 17 supplies solid fuel (biomass fuel in the present embodiment) from the upper side to the lower rotary table 12, and the rotary table 12 pulverizes the supplied solid fuel with the rollers 13. Also called a crushing table.

When the solid fuel is supplied from the fuel supply unit 17 toward the center of the rotary table 12, the solid fuel is guided to the outer peripheral side of the rotary table 12 by the centrifugal force due to the rotation of the rotary table 12, and is brought into contact with the roller 13. It is sandwiched and crushed. The crushed solid fuel becomes fuel after crushing, and is rolled up by the carrier gas (hereinafter referred to as “primary air”) guided from the primary gas supply unit (hereinafter referred to as “primary air flow path”) 100a and classified. Guided to the aircraft 16. That is, blow-out ports 15 (see FIG. 2) are provided at a plurality of locations on the outer peripheral side of the turntable 12 so that the primary air flowing in from the primary air flow passage 100a flows into the space above the turntable 12 in the housing 11. ing. A vane (not shown) is installed above the outlet 15 and gives a swirling force to the primary air blown out from the outlet 15. The primary air to which the swirling force is given by the vane becomes an air flow having a swirling velocity component and guides the solid fuel crushed on the rotary table 12 to the upper classifier 16 in the housing 11. Of the pulverized solid fuel mixed with the primary air, most of the coarse-grained fuel having a larger particle size is classified by the classifier 16 or falls and rotates without reaching the classifier 16. It is returned to the table 12 and crushed again.

The roller (crushing roller) 13 is a rotating body that crushes the solid fuel supplied from the fuel supply unit 17 to the rotary table 12. The roller 13 is pressed against the upper surface of the rotary table 12 and cooperates with the rotary table 12 to crush the solid fuel. In FIG. 1, only one roller 13 is shown as a representative, but a plurality of rollers 13 are arranged facing each other at regular intervals in the circumferential direction so as to press the upper surface of the rotary table 12. It For example, the three rollers 13 are arranged at equal intervals in the circumferential direction with an angular interval of 120° on the outer peripheral portion. In this case, the portions where the three rollers 13 are in contact with the upper surface of the rotary table 12 (the portions that are pressed) have the same distance from the rotation center axis of the rotary table 12.

The roller 13 is swingable up and down by a journal head 45, and is supported by the upper surface of the rotary table 12 so that the roller 13 can move toward and away from the upper surface of the rotary table 12. When the rotary table 12 rotates while the outer peripheral surface of the roller 13 is in contact with the upper surface of the rotary table 12, the roller 13 receives the rotational force from the rotary table 12 and rotates together. When the solid fuel is supplied from the fuel supply unit 17, the solid fuel is pressed between the roller 13 and the rotary table 12 and pulverized to become a pulverized fuel composed of a fine grain fuel and a coarse grain fuel.

The support arm 47 of the journal head 45 is supported by a support shaft 48 whose middle portion extends in the horizontal direction. That is, the support arm 47 is supported on the side surface of the housing 11 so as to be swingable in the vertical direction of the roller about the support shaft 48. A pressing device 49 is provided on the upper end of the support arm 47 on the vertically upper side. The pressing device 49 is fixed to the housing 11 and applies a load to the roller 13 via the support arm 47 or the like so as to press the roller 13 against the rotary table 12. The pressing force of the pressing device 49 (that is, the crushing load) is controlled by the control unit 50.

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

The classifier 16 is provided on the upper part of the housing 11 and has a hollow substantially inverted conical shape. The classifier 16 is provided with a plurality of classifying blades (blades) 16a extending in the vertical direction at the outer peripheral position thereof. The lower end of each classification blade 16a is fixed to the fixed portion. The classifying blades 16a are provided in parallel around the central axis of the classifier 16 with a predetermined interval (uniform interval). The classifier 16 is a device that classifies the solid fuel crushed by the rollers 13 into a coarse particle fuel having a particle size larger than a predetermined particle size and a fine particle fuel having a particle size not larger than a predetermined particle size. The classifier 16 is a rotary classifier that classifies by rotating about an axis of rotation in the vertical direction, and is also called a rotary separator. A rotation driving force is applied to the classifier 16 by the motor 18. The rotation speed of the motor 18 is controlled by the control unit 50.

The crushed fuel of the solid fuel that has reached the classifier 16 is struck by the classifying blade 16a due to the relative balance between the centrifugal force generated by the rotation of the classifying blade 16a and the centripetal force of the primary air flow. It is dropped, returned to the rotary table 12 and pulverized again, and the fine fuel particles are guided to the discharge port 19 in the ceiling portion 42 of the housing 11.

The fine-grained fuel classified by the classifier 16 is discharged from the discharge port 19 to the supply flow path 100b, and is conveyed to the downstream process together with the primary air. The fine-grained fuel that has flowed out to the supply passage 100b is supplied to the burner unit 220 of the boiler 200.

The fuel supply unit 17 is attached such that the lower end extends vertically into the housing 11 so as to penetrate the upper end of the housing 11 and the solid fuel injected from the upper portion is substantially centered on the rotary table 12. Supply. The fuel supply unit 17 is supplied with solid fuel from the coal feeder 20.

The coal feeder 20 includes a bunker 21, a transfer unit 22, and a motor 23. The transport unit 22 transports the solid fuel discharged from the lower end portion of the down spout unit 24 located immediately below the bunker 21 by the driving force applied from the motor 23, and is guided to the fuel supply unit 17 of the mill 10.
Usually, primary air for carrying finely divided fuel, which is crushed solid fuel, is supplied to the inside of the mill 10, and the pressure is higher than atmospheric pressure. Fuel is held in a stacked state inside the down spout portion 24, which is a vertically extending pipe just below the bunker 21, and the fuel layer stacked inside the down spout portion 24 causes The sealability is ensured so that the primary air and the particulate fuel do not flow back. The supply amount of the solid fuel supplied to the mill 10 may be adjusted by the belt speed of the belt conveyor of the transport unit 22.

The blower unit 30 is a device that dries the solid fuel crushed by the rollers 13 and blows primary air (carrier gas) for supplying to the classifier 16 into 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 from a heat exchanger such as an air preheater. A hot gas damper 30c is provided on the downstream side of the hot gas blower 30a. The opening of the hot gas damper 30c is controlled by the controller 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 the outside air at room temperature. A cold gas damper 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 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. Is determined by the mixing ratio of the primary air blown by the cold gas blower 30b and controlled by the control unit 50. In addition, by guiding a part of the combustion gas discharged from the boiler 200 that has passed through the environmental device such as the electric dust collector through the gas recirculation blower to the primary air blown by the hot gas blower 30a to form a mixture, You may adjust the oxygen concentration of the primary air which flows in from the primary air flow path 100a.

In the present embodiment, the state detection unit 40 of the housing 11 transmits the measured or detected data to the control unit 50. The state detection unit 40 is, for example, a differential pressure measuring unit, and a portion where primary air flows from the primary air flow channel 100a into the mill 10 and a discharge of primary air and fine fuel from the inside of the mill 10 to the supply flow channel 100b. The pressure difference with the outlet 19 is measured as the pressure difference in the mill 10. Depending on the classification performance of the classifier 16, the increase/decrease in the circulation amount of the pulverized fuel circulating the solid fuel circulating in the mill 10 and the increase/decrease in the differential pressure in the mill 10 corresponding to this change. That is, since the fine particle fuel discharged from the discharge port 19 can be adjusted and managed with respect to the solid fuel supplied to the inside of the mill 10, the particle size of the fine particle fuel does not affect the combustibility of the burner section 220. A large amount of fine-grained fuel can be supplied to the burner unit 220 provided in the boiler 200. Further, in the present embodiment, the pressure detecting units 53 and 54 are provided separately from the above-mentioned differential pressure measuring means (measuring means for measuring the differential pressure of the mill) for measuring the differential pressure between the discharge port 19 and the mill 10. This will be described later with reference to FIG.

The state detection unit 40 is, for example, a temperature measurement unit, and the temperature is adjusted by the blower unit 30 that blows the primary air for supplying the solid fuel crushed by the rollers 13 to the classifier 16 into the housing 11. The temperature of the generated primary air in the housing 11 is detected, and the blower unit 30 is controlled so as not to exceed the upper limit temperature. In addition, since the primary air is cooled in the housing 11 by transporting the pulverized material while drying it, the temperature of the upper space of the housing 11 is, for example, about 60 to 80° C.

The control unit 50 is a device that controls each unit of the solid fuel crushing system 100. The control unit 50 can control the rotation of the rotary table 12 with respect to the operation of the mill by transmitting a drive instruction to the drive unit 14, for example. The controller 50 adjusts the classification performance by transmitting a drive instruction to the motor 18 of the classifier 16 to control the number of revolutions, thereby optimizing the differential pressure in the mill 10 and supplying fine fuel. Can be stabilized. In addition, the control unit 50 adjusts the supply amount of the solid fuel supplied by the transfer unit 22 to the fuel supply unit 17 by transmitting the drive instruction to the motor 23 of the coal feeder 20, for example. You can In addition, the control unit 50 can control the flow rate and temperature of the primary air by controlling the opening degree of the hot gas damper 30c and the cold gas damper 30d by transmitting the opening degree instruction to the blower unit 30.

The control unit 50 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing/arithmetic processing. As a result, various functions are realized. The program is installed in a ROM or other storage medium in advance, provided in a state of being stored in a computer-readable storage medium, or delivered via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

Next, the boiler 200 which combusts using the fine grain fuel supplied from the solid fuel grinding system 100, and produces|generates steam is demonstrated. The boiler 200 includes a furnace 210 and a burner section 220.

The burner unit 220 burns the fine particle fuel using primary air containing fine particle fuel supplied from the supply passage 100b and secondary air supplied from a heat exchanger (not shown) to form a flame. Is. Combustion of the particulate 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 a predetermined treatment by an environmental device (not shown in a denitration device, an electric dust collector, etc.), and heat exchange with outside air is performed by a heat exchanger (not shown) such as an air preheater. It is carried out, is guided to a chimney (not shown) through an induction fan (not shown), and is discharged to the atmosphere. The outside air heated by heat exchange with the combustion gas in the heat exchanger is sent to the hot gas blower 30a described above.
Water supplied 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) and a generator (not shown) is rotationally driven to generate electricity.

<Powder layer height measurement>
FIG. 2 shows a powder layer height measuring means 52 by a pressure detection unit provided separately from the state detection unit 40. The pressure detection unit (manometer 53, detection pipe 54) has a difference that is different from the mill pressure difference, which is the pressure difference measured between the upstream side (inside the mill 10) and the downstream side (discharge port 19) of the mill 10 measured by the state detection unit 40. Detect pressure. The powder layer B1 refers to a region in which the pulverized fuel blown up by the primary air stays at a higher concentration than others. The powder layer height measuring means 52 includes a plurality of manometers 53. As the manometer 53, for example, a digital type is used. The measurement value of the manometer 53 is transmitted to the control unit 50.

A detection tube 54 inserted into the inside of the mill 10 is connected to each end of the U-shaped tube of the manometer 53. An opening end 54 a that opens inside the mill 10 is provided at the tip of each detection tube 54. The open ends 54a of the pair of detection tubes 54 connected to the common manometer 53 are installed adjacent to each other at a predetermined interval in the vertical direction. The open ends 54a of the detection tubes 54 connected to the other manometers 53 are also provided at different positions with a predetermined interval in the vertical direction. It is preferable that the distance between the opening ends 54a adjacent to each other in the vertical direction is constant, for example, 50 mm or more and 200 mm or less. The height (powder layer height H1) of the powder layer B1 formed of the pulverized solid fuel staying on the rotary table 12 is, for example, vertically upward with the reference position being the crush surface of the rotary table 12. In the front and rear positions corresponding to the position of the height of the powder layer B1, the intervals may be narrower than those of other parts in order to improve the measurement accuracy (see FIG. 4).

Each detection tube 54 is attached so as to penetrate, for example, a manhole cover 56 provided in the housing 11, and the detection tube 54 can be removed together with the cover 56. As a result, the powder layer height measuring means 52 can be easily attached and detached without changing the configuration of the mill 10.
Each of the detection tubes 54 is preferably formed of a material having wear resistance, and may be provided with a protection means that is not damaged by vibration.

The open end 54a of the detection tube 54 is provided in the height direction between the rotary table 12 and the lower end of the classifier 16. The installation height of each opening end 54a is stored as data in the storage area of the control unit 50. Thereby, the pressure distribution in the vertical direction can be obtained by obtaining the differential pressure by the manometer 53.

Each open end 54a is bent in the mill 10 so as to be oriented in a direction intersecting the upstream side direction of the primary air flow. In this embodiment, it is provided so as to face the downstream side of the primary air flow. Specifically, for example, the tip of each detection tube 54 may be bent so as to follow the primary air flow. As a result, the static pressure can be accurately measured by reducing the influence of the dynamic pressure of the primary air flow in the mill 10.

An on-off valve 54b is provided in each of the detection tubes 54. The on-off valve 54b is opened (white) when the differential pressure is measured by the manometer 53, and closed (black) when the differential pressure is not measured. Further, the on-off valve 54b is closed when the manometer 53 is replaced. The open/close control of the open/close valve 54b may be performed by the control unit 50.

As shown in FIG. 3, when the mill 10 is viewed in a plan view, the detection tubes 54 may be provided at different positions in the circumferential direction around the rotation axis of the rotary table 12, that is, in the circumferential direction of the housing 11. At this time, the detection tube 54 is preferably provided between the adjacent rollers 13 so as to avoid interference with the rollers 13.

As shown in FIG. 4, a purge pipe 54c may be connected to each detection pipe 54. An air supply source (not shown) is connected to the upstream side of the purge pipe 54c. Purge air (purge fluid) can be made to flow from the purge pipe 54c toward the open end 54a of the detection pipe 54. As a result, the detection tube 54 can be prevented from being blocked by the pulverized fuel that remains in the powder layer B1. Therefore, the purge air is not normally supplied, but is supplied when the blockage of the detection tube 54 is detected. The purge air may be supplied periodically. As the purge air, an inert gas such as nitrogen may be used instead of air.
In addition, in FIG. 4, as described above, the installation interval L1 of the opening ends 54a at the position corresponding to the powder layer height H1 is set smaller than the installation interval L2 of the opening ends 54a at other positions. It is shown.

5A and 5B show an example of powder layer height measurement.
As shown in FIG. 5A, manometers 53A, 53B, 53C, and 53D are installed so that the open ends 54a are sequentially positioned vertically upward from the turntable 12. Therefore, the manometer 53A measures the differential pressure at the lowermost position, the differential pressure above it is measured by the manometer 53B, the differential pressure above it is measured by the manometer 53C, and the uppermost differential pressure is measured by the manometer 53D. measure. At this time, assuming that the powder layer height H1 exists between the manometer 53B and the manometer 53C, the measurement result is as shown in FIG. 5B. That is, the manometer 53A and the manometer 53B show a larger differential pressure than the upper manometer 53C and the manometer 53D. This is because the powder layer B1 has a high density and thus a large pressure loss. Therefore, in the case of the measurement result of FIG. 5B, it can be seen that the powder layer height H1 is located between the manometer 53B and the manometer 53C. The controller 50 determines the powder layer height H1.

<Operating conditions of mill 10 and powder bed height H1>
6A and 6B show the increase and decrease of the powder bed height H1 according to the respective operating conditions. 6A and 6B, the increase and decrease of the powder layer height H1 on the vertical axis are shown by a straight line, but they are not necessarily proportional and the magnitude of the increase and decrease gradient of the powder layer height H1 is shown. It does not mean that the powder layer height H1 tends to increase or decrease.
FIG. 6A shows a case where the fuel supply amount (solid fuel supply amount) Qb for supplying the biomass fuel to the classifier 16 is set as the operating condition. The fuel supply amount Qb is the fuel amount of the biomass fuel supplied onto the rotary table 12, and is therefore substantially proportional to the powder bed height H1. By increasing the fuel supply amount Qb, the amount of fuel after pulverization in the fluid that is a mixture of the fuel after pulverization containing coarse particles and fine particles and primary air is increased, and by decreasing the amount of fuel supply Qb, the amount of fuel after pulverization is decreased. Become. Therefore, when the fuel supply amount Qb is reduced, the powder bed height H1 is reduced. Therefore, the powder bed height H1 can be reduced by reducing the fuel supply amount Qb from the current fuel supply amount Qb0.

FIG. 6B shows a case where the carrier gas flow rate (primary air flow rate) Qa supplied to the mill 10 is set as the operating condition. The carrier gas flow rate (primary air flow rate) Qa is approximately inversely proportional to the powder layer height H1. Due to the increase of the carrier gas flow rate (primary air flow rate) Qa, the amount of pulverized fuel in the mixed fluid of the pulverized fuel containing coarse particles and fine particles and the primary air increases, but the carrier gas flow rate ( This is because when the primary air flow rate) Qa is increased, the amount of gas with respect to the fuel after pulverization increases and the powder density decreases. Therefore, if the carrier gas flow rate Qa is increased, the powder layer height H1 is decreased. Therefore, the powder layer height H1 can be decreased by increasing the carrier gas flow rate (primary air flow rate) Qa from the current carrier gas flow rate (primary air flow rate) Qa0.

<Changing operating conditions during trial operation before operation starts>
Next, a control method using the above-mentioned powder layer height measuring means 52 will be described.
First, a control method for changing conditions during operation will be described.

As shown in FIG. 7, the mill 10 starts the test operation before starting the operation, and after reaching the steady operation, starts the control (step S0).
Then, the control unit 50 determines whether or not the powder layer height H1 obtained by the powder layer height measuring means 52 exceeds a predetermined value (step S1). The predetermined value of the powder bed height H1 used here was determined in accordance with the test operation before the operation of the mill 10 or the actual results of the same model or the like, or the powder bed height H1 when the same model coal was operated. It is a fixed value.

When the powder layer thickness H1 does not exceed the predetermined value, the powder layer height measuring means 52 directly monitors the powder layer height H1.

When the powder bed height H1 exceeds the predetermined value, the control unit 50 reduces the fuel supply amount Qb of the biomass fuel supplied onto the rotary table 12 (step S2). As a result, the powder layer height H1 decreases (see FIG. 6A).

Then, the control unit 50 determines whether or not the powder layer thickness H1 exceeds a predetermined value in step S3 as in step S1. If the powder layer thickness H1 still exceeds the predetermined value, the carrier gas flow rate (primary air flow rate) Qa, which is the supply amount of primary air to the mill 10, is increased (step S4). As a result, the powder layer height H1 is reduced (see FIG. 6B). Note that this step S4 may be performed at the same time as step S2. However, when the carrier gas flow rate (primary air flow rate) Qa is increased after step S2, the primary air is supplied after the pulverized fuel existing inside the mill 10 is reduced, so the carrier gas flow rate (primary air flow rate) ) It is possible to suppress an increase in Qa and suppress the auxiliary machine power required for the hot gas blower 30a and the cold gas blower 30b for supplying primary air.

When step S4 ends, a series of control for changing operating conditions ends (step S5).

The change of the operating conditions of the mill 10 described above may be used during the test operation before the start of the operation of the mill 10. The control unit 50 stores each operating condition obtained during the test operation as an initial value in a storage unit (not shown). As a result, the operating condition that the powder bed height H1 becomes less than the predetermined value can be set in advance before the operation.

<Operation and effect of this embodiment>
According to this embodiment, the following operational effects are exhibited.
The pulverized biomass fuel (solid fuel) pulverized by the rotary table 12 and the rollers 13 becomes the pulverized fuel and forms a powder layer height H1 of a predetermined height on the rotary table 12. When the powder layer height H1 increases and approaches the classifier 16 above the vertical direction, some coarse particles are not classified by the classifier 16 and flow out to the downstream side of the mill 10 to deteriorate the classification performance. For this reason, the finished particle size of the fine fuel particles may be reduced, and fine particles and some coarse particles may be mixed and supplied to the burner portion, and the combustibility in the burner portion may be reduced. Therefore, the powder layer height measuring means 52 is used to measure the powder layer height H1. As a result, it is possible to control the appropriate powder layer height H1 and suppress the deterioration of the classification performance.

Between the upper part of the rotary table 12 and the lower end of the classifier 16, detection tubes 54 connected to the manometer 53 as a plurality of pressure detection parts are provided at different height positions. Thereby, the pressure distribution in the height direction can be obtained. Since the powder layer B1 has a higher density than gas layers other than the powder layer B1 (for example, an air layer), the pressure loss is large. Therefore, if the pressure distribution in the height direction is obtained, it can be seen that the height position where the change in pressure loss is large corresponds to the powder layer height H1.

The detection tube 54 is provided as a pressure detection unit at different positions in the circumferential direction around the rotary shaft of the rotary table 12. With this, the detection tubes 54 can be dispersedly arranged at different height positions in the circumferential direction, so that an installation space can be secured when disposing the plurality of pressure detection units.

The control unit 50 changes the operating condition based on the detection signal of the powder layer height measuring means 52 so as to reduce the powder layer height H1. As a result, by realizing an appropriate powder layer height H1, it is possible to maintain desired classification performance.
Specifically, the powder bed height H1 is reduced by reducing the fuel supply amount Qb of the biomass fuel supplied onto the rotary table 12 (see FIG. 6A). Further, the powder layer height H1 is reduced by increasing the carrier gas flow rate (primary air flow rate) Qa of the primary air flowing from the rotary table 12 toward the classifier 16 (see FIG. 6B).

In the present embodiment, as shown in FIGS. 5A and 5B, the manometer 53 used as the powder layer height measuring means 52 is used to measure the differential pressure in the height direction inside the mill 10. However, the means for measuring the differential pressure in the height direction above the rotary table 12 is not limited to this. For example, as shown in FIG. 8A, when a plurality of manometers 53 are provided and a pair of adjacent detection tubes 54 connected to each manometer 53 is used as a pair, the open end 54a (see FIG. 5A) of one detection tube 54 is connected to the mill 10 And the open end 54a of the other detection tube 54 is opened to the atmosphere. As a result, as shown in FIG. 8B, it is possible to obtain the differential pressure with respect to the atmosphere at each powder layer height H1, that is, the absolute pressure. When the pressure distribution in absolute pressure is obtained as shown in FIG. 8B, the inflection point of the pressure becomes the boundary between the powder layer B1 and the gas layer, so that the powder layer height H1 can be obtained. Further, since the absolute pressure can be obtained, the density and density distribution of the powder layer B1 can be obtained, and the operating conditions can be adjusted in more detail.

Further, as a means for measuring the pressure in the height direction above the turntable 12, pressure sensors installed at different height positions may be used.

Further, in the present embodiment, the description has been made assuming that only the biomass fuel is crushed by the mill 10, but the present invention is not limited to this as the solid fuel crushed by the mill 10, and other solid fuels are used. Or a mixed fuel of coal and biomass fuel.

1 power plant 10 mils (solid fuel grinder)
11 housing 12 rotary table 13 roller (crushing roller)
14 Drive unit 15 Air outlet 16 Classifier (rotary classifier)
16a classification blade
17 Fuel Supply Section 18 Motor 20 Coal Feeder 21 Bunker 22 Conveying Section 23 Motor 24 Down Spout Section 30 Blower Section 30a Hot Gas Blower 30b Cold Gas Blower 30c Hot Gas Damper 30d Cold Gas Damper 40 State Detection Unit (Temperature Measuring Device, Differential Pressure Measurement means)
41 bottom face part 42 ceiling part 45 journal head 47 support arm 48 support shaft 49 pressing device 50 control unit 52 powder layer height measuring means 53 manometer (pressure detection unit)
54 Detector tube (pressure detector)
54a Open End 54b Opening/Closing Valve 54c Purge Pipe 56 Lid 100 Solid Fuel Grinding System 100a Primary Air Flow Path (Primary Gas Supply)
100b Supply flow path 200 Boiler 210 Furnace 220 Burner part B1 Powder layer H1 Powder layer height Qa Carrier gas flow rate (primary air flow rate)
Qb Fuel supply amount (solid fuel supply amount)

Claims (8)

A rotating table,
A crushing roller for crushing the solid fuel between the rotary table,
A rotary classifier located vertically above the rotary table for classifying the crushed fuel crushed by the crushing roller;
Powder layer height measuring means for measuring the powder layer height due to the pulverized fuel formed on the rotary table;
Solid fuel pulverizer equipped with. The solid fuel crushing machine according to claim 1, wherein the powder bed height measuring means includes a plurality of pressure detection units provided at different height positions between the rotary table and the rotary classifier. apparatus. The solid fuel crushing device according to claim 2, wherein the plurality of pressure detection units are provided at different positions in the circumferential direction of the rotary table. A control unit for obtaining a detection signal of the powder layer height measuring means,
The fixed fuel crushing device according to any one of claims 1 to 3, wherein the control unit changes the operating condition based on the detection signal so as to reduce the powder bed height. The solid fuel crushing apparatus according to claim 4, wherein the control unit changes the operating condition so as to reduce the amount of solid fuel supplied to the rotary table. The solid fuel crushing apparatus according to claim 5, wherein the control unit changes the operating condition so as to increase the flow rate of the carrier gas flowing from the rotary table toward the rotary classifier. A solid fuel crushing device according to any one of claims 1 to 6,
A boiler that burns the pulverized fuel pulverized by the solid fuel pulverizer to produce steam.
A power generation unit that generates power using the steam generated by the boiler,
Power plant. A rotating table,
A crushing roller for crushing the solid fuel between the rotary table,
A rotary classifier located vertically above the rotary table for classifying the crushed fuel crushed by the crushing roller;
A method for controlling a solid fuel pulverizing apparatus comprising:
A method for controlling a solid fuel crushing device for measuring a height of a powder layer formed by the crushed fuel formed on the rotary table.

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