CN111482242B

CN111482242B - Solid fuel pulverizer, power generation facility provided with same, and control method therefor

Info

Publication number: CN111482242B
Application number: CN202010075975.6A
Authority: CN
Inventors: 泽昇吾; 松本慎治; 植田优也; 栗原诚矢; 山口聪太朗
Original assignee: Mitsubishi Power Ltd
Current assignee: Mitsubishi Power Ltd
Priority date: 2019-01-25
Filing date: 2020-01-22
Publication date: 2022-01-04
Anticipated expiration: 2040-01-22
Also published as: JP2020116536A; JP7362253B2; CN111482242A

Abstract

The invention provides a solid fuel pulverizer, a power generation facility provided with the same, and a control method thereof, which can detect coarse solid fuel accumulated in a rotary classifier. The solid fuel pulverizer includes: a rotary table (12); a roller (13) that pulverizes the solid fuel between the roller and the rotating table (12); a classifier (16) that is provided with a plurality of classifying blades (16a) that rotate about a rotation axis and that are vertically provided along a circumferential direction with respect to a fixed portion (16b), and that classifies the pulverized fuel that has been pulverized by the roller (13); a discharge port (19) which is connected to the inner peripheral side of a plurality of classifying paddles (16a) vertically arranged in the circumferential direction, namely, the inner part (SP1) of the classifier (16) and discharges the fine powder fuel classified by the classifier (16); and a differential pressure detection unit (43) that detects the differential pressure between the pressure inside (SP1) the classifier (16) and the pressure outside (SP2) the classifier (16).

Description

Solid fuel pulverizer, power generation facility provided with same, and control method therefor

Technical Field

The present invention relates to a solid fuel pulverizer, a power generation facility including the same, and a method for controlling the solid fuel pulverizer.

Background

Conventionally, a solid fuel such as coal or biomass fuel is pulverized into fine powder having a particle size smaller than a predetermined particle size by a pulverizer (grinder) and supplied to a combustion apparatus. The grinding machine crushes and pulverizes solid fuel such as coal and biomass fuel introduced into the rotary table between the rotary table and the roller, and by a carrier gas supplied from the outer periphery of the rotary table, the pulverized fuel is pulverized into fine powder, and the fuel having a small particle size is screened by a classifier, and is carried to a boiler and burned by a combustion device. In a thermal power plant, power is generated by generating steam through heat exchange with combustion gas generated by combustion in a boiler and driving a turbine with the steam.

The pulverized solid fuel (pulverized fuel) pulverized by the mill is classified into fine particles and coarse particles by a rotary classifier provided at an upper portion of the mill. The fine fuel particles pass between the blades of the rotary classifier and are sent to a combustion apparatus as a post-process, and the coarse fuel particles collide with the blades of the rotary classifier and fall down to the rotary table to be pulverized again. Thus, due to the classification performance of the rotary classifier, an increase or decrease in the circulation amount of the pulverized fuel of the solid fuel circulating between the vicinity of the rotary classifier and the vicinity of the rotary table occurs in the grinder.

In such a grinder, in order to grasp the internal state of the ground fuel ground during operation, a grinder differential pressure, which is a differential pressure between the upstream side of the carrier gas supplied into the grinder and the inside of the grinder, is measured (see patent document 1).

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 8-141420

In recent years, effective use of renewable energy has been advanced, and there is an increasing demand for biomass fuel to be pulverized using an existing coal mill. However, pulverized particles of biomass fuel are easier to be carried to the vicinity of the rotary classifier by the carrier gas because of a smaller specific gravity than pulverized particles of coal (pulverized coal), and if coarse particles are mixed into the rotary classifier of the mill, the coarse particles stay in a region where the flow of the carrier gas is small and are not carried out of the mill. When coarse particles of the biomass fuel are deposited in the rotary classifier, the classification performance of the rotary classifier is degraded, and therefore, it is necessary to change the operating conditions of the mill so that the coarse particles are not deposited.

However, it is difficult to accurately detect the state of coarse particles deposition of the biomass fuel in the rotary classifier at the measurement point for detecting the differential pressure of the mill as shown in patent document 1, and the operating conditions of the mill cannot be appropriately changed.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a solid fuel pulverizer capable of detecting coarse fuel deposited inside a rotary classifier, a power generation plant including the same, and a method for controlling the solid fuel pulverizer.

A solid fuel pulverizer according to an embodiment of the present invention includes: a rotating table; a pulverization roller configured to pulverize the solid fuel between the pulverization roller and the turntable; a rotary classifier including a plurality of blades that rotate about a rotation axis and are provided upright on a fixed portion in a circumferential direction, the rotary classifier classifying the pulverized fuel pulverized by the pulverization roller; an outlet connected to an inner peripheral side of the plurality of vanes vertically provided in the circumferential direction, that is, an inside of the rotary classifier, and discharging the particulate fuel classified by the rotary classifier; and a differential pressure detection unit that detects a differential pressure between the pressure inside the rotary classifier and the pressure outside the rotary classifier.

The solid fuel pulverized by the rotary table and the pulverizing roller is classified into coarse fuel and fine fuel by a rotary classifier rotating about a vertical rotation axis. The classified particulate fuel is discharged from a discharge port connected to the inside of the rotary classifier to the subsequent process side. The classified coarse fuel is returned to the outside of the rotary classifier. However, a part of the coarse fuel may pass through between the vanes and not return to the outside of the rotary classifier, and may be accumulated in a region where the airflow conveying force of the conveying gas is low, such as a fixed portion to which each vane is fixed. When the coarse fuel is deposited on the fixed portion, the lower portion of each blade is buried in the coarse fuel, and the effective area of each blade for classifying the pulverized fuel of the solid fuel is reduced, thereby degrading classification performance. Therefore, a differential pressure detecting unit is provided that detects a differential pressure between the inside and the outside of the rotary classifier. This makes it possible to detect that the lower portion of each blade is filled with the coarse fuel and the pressure loss inside and outside the rotary classifier increases, and to detect that the coarse fuel is deposited inside the rotary classifier.

As the pressure outside the rotary classifier, for example, a pressure inside a mill body housing the rotary classifier on the outer peripheral side of the rotary classifier can be used. However, in the case where the change in the pressure loss of the blade when the pressure change in the main body of the polishing machine is small can be measured, the absolute pressure change in the rotary classifier may be measured, and as the pressure outside the rotary classifier in this case, a constant reference pressure may be used as long as the pressure in the main body of the polishing machine does not change greatly, and for example, the atmospheric pressure outside the main body of the polishing machine may be used.

As the solid fuel, for example, biomass fuel or a mixed fuel of biomass fuel and coal can be used.

In the solid fuel pulverizer according to the embodiment of the present invention, the pressure difference detection unit includes a detection pipe that opens into the interior of the rotary classifier and is bent so as to be oriented in a direction intersecting with an upstream direction of the flow in the interior.

The pressure inside the rotary classifier can be detected by providing a detection tube having an open end inserted into the rotary classifier.

The opening of the detection pipe is preferably bent to be directed in a direction intersecting with the upstream direction of the flow toward the inside of the discharge port side. This reduces the influence of the dynamic pressure of the flow inside the rotary classifier, and can accurately measure the static pressure.

Further, the detection tube may be removed from the inside of the rotary classifier and the outside of the rotary classifier, respectively. Thus, the detection tube can be detached when the pressure measurement is not necessary, and entry of pulverized fuel and the like into the detection tube can be suppressed.

In the solid fuel pulverizer according to the embodiment of the present invention, a purge pipe capable of supplying a purge fluid is connected to the detection pipe.

By flowing out the purge fluid (for example, air or nitrogen gas) having a flow rate that does not affect the pressure measurement from the purge pipe, the purge fluid can be circulated in the detection pipe, and the pulverized fuel and the like can be prevented from entering the detection pipe and blocking the detection pipe. For example, the purge fluid is introduced from the vicinity of the tip of the detection tube, and the purge fluid is ejected from the tip into the rotary classifier, thereby preventing clogging.

In the solid fuel pulverizer according to one embodiment of the present invention, the solid fuel pulverizer includes a control unit that acquires a detection signal of the differential pressure detection unit, and the control unit outputs a first signal and determines that coarse fuel is deposited in the rotary classifier when the differential pressure acquired by the differential pressure detection unit exceeds a predetermined value or when a change in the differential pressure acquired by the differential pressure detection unit with respect to time exceeds a predetermined value.

The control unit outputs a first signal when the value of the differential pressure or the amount of change in the differential pressure with respect to time obtained by the differential pressure detection unit exceeds a predetermined value. Thus, an increase in the differential pressure value or an increase in the differential pressure change rate due to the deposition of coarse fuel in the rotary classifier can be detected, and it can be determined that deposition has occurred.

In the solid fuel pulverizer according to the embodiment of the present invention, the control unit outputs a second signal for changing an operation condition to suppress the accumulation of the coarse fuel in the rotary classifier simultaneously with or after the first signal is output.

The operation condition is changed by a second signal for suppressing the accumulation of the coarse fuel at the same time as or after the accumulation of the coarse fuel in the rotary classifier is detected by the first signal. This can suppress accumulation and deposition of coarse fuel deposited inside the rotary classifier.

In the solid fuel pulverizer according to an embodiment of the present invention, the control unit changes the operating condition so as to decrease the rotation speed of the rotary classifier.

The rotational speed of the rotary classifier is reduced to adjust the classification performance, reduce the pressure loss of the rotating blades, and rationalize the pressure difference of the rotary classifier. This makes it possible to change the flow state inside the rotary classifier and to facilitate the discharge of the deposited coarse fuel.

The change of the operating conditions may be used during a test operation of the solid fuel pulverizer, or may be used during an operation.

In the solid fuel pulverizer according to an embodiment of the present invention, the controller changes the operating condition so as to decrease a supply amount of the solid fuel supplied onto the turntable.

The amount of the solid fuel supplied to the rotary table is reduced, so that the amount of the fuel produced after pulverization is reduced, the coarse fuel entering the rotary classifier through the space between the blades is reduced, the coarse fuel is continuously discharged while suppressing an increase in the amount of the coarse fuel deposited, and the amount of the coarse fuel deposited in the rotary classifier can be reduced.

The reduction of the supply amount of the solid fuel may be performed simultaneously with the reduction of the rotation speed of the rotary classifier described above, or may be performed after the reduction of the rotation speed of the rotary classifier.

In the solid fuel pulverizer according to an embodiment of the present invention, the control unit changes the operating conditions so that a flow rate of the carrier gas flowing from the rotary table toward the rotary classifier is increased.

By increasing the flow rate of the carrier gas flowing from the turntable toward the rotary classifier, the discharge of the coarse fuel accumulated in the rotary classifier can be promoted.

The flow rate of the carrier gas may be increased simultaneously with the reduction in the rotation speed of the rotary classifier and the reduction in the supply amount of the solid fuel, or may be increased after the reduction in the supply amount of the solid fuel. 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 after coarse fuel accumulated in the rotary classifier is discharged to a certain extent, and therefore, the increase in the supply amount of the carrier gas can be suppressed, and the auxiliary power required by the blower for supplying the carrier gas can be suppressed.

In the solid fuel pulverizer according to an embodiment of the present invention, the controller changes the operating condition so as to increase a pulverizing load, which is a load of the pulverizing roller on the rotary table.

By increasing the grinding load, which is the load of the grinding roller on the rotary table, the solid fuel can be further finely ground. This suppresses the generation of coarse fuel contained in the pulverized fuel, and reduces the amount of coarse fuel entering the rotary classifier, thereby suppressing the accumulation of coarse fuel in the rotary classifier.

The increase in the pulverization load is preferably performed after the rotation speed of the rotary classifier is decreased, the supply amount of the solid fuel is decreased, and the flow rate of the carrier gas is increased, and also, the improvement of the deposition inhibition of the coarse fuel and the improvement of the differential pressure between the inside and the outside of the rotary classifier are not observed to be small. This is because the inhibition of the accumulation of the coarse fuel due to the increase in the pulverization load is slower in the time response than in other operation conditions, and also leads to an increase in the power.

In the solid fuel pulverizer according to an embodiment of the present invention, the control unit changes the operating condition so as to temporarily increase the rotation speed of the rotary classifier.

The rotation speed of the rotary classifier is once increased and the rotation speed is returned to the original rotation speed again to increase the centrifugal force, so that the centrifugal force is increased and acts on the coarse fuel accumulated inside the rotary classifier, and the coarse fuel can be discharged from the rotary classifier on the outer peripheral side of the rotary classifier from between the blades. This can reduce coarse fuel deposited inside the rotary classifier. The coarse fuel discharged to the outside of the outer periphery of each vane falls onto the turntable and is pulverized again.

By changing the operating conditions during the operation of the solid fuel pulverizer, the solid fuel pulverizer can be continuously operated.

Further, a power generation facility according to an embodiment of the present invention includes: the solid fuel pulverizer of any one of the above; a boiler that burns the solid fuel pulverized by the solid fuel pulverizer to generate steam; and a power generation unit that generates power using the steam generated by the boiler.

In addition, a method for controlling a solid fuel pulverizer according to an embodiment of the present invention includes: a rotating table; a pulverization roller configured to pulverize the solid fuel between the pulverization roller and the turntable; a rotary classifier including a plurality of blades that rotate about a rotation axis and are provided upright on a fixed portion in a circumferential direction, the rotary classifier classifying the pulverized fuel pulverized by the pulverization roller; and a discharge port connected to an inner periphery of the plurality of vanes vertically provided in the circumferential direction, that is, to an inside of the rotary classifier, and discharging the particulate fuel classified by the rotary classifier, wherein in the method of controlling the solid fuel pulverizer, a pressure difference between a pressure inside the rotary classifier and a pressure outside the rotary classifier is detected.

Effects of the invention

Since the pressure difference detection means for detecting the pressure difference between the inside and the outside of the rotary classifier is provided, the coarse fuel accumulated in the rotary classifier can be detected.

Drawings

Fig. 1 is a schematic configuration diagram showing a power generation facility according to an embodiment of the present invention.

Fig. 2 is a longitudinal sectional view showing an outline of the grinding machine of fig. 1.

Fig. 3 is a longitudinal sectional view showing the periphery of the mounting position of the downstream side detection pipe.

Fig. 4A is a graph showing the deposition ratio of the coarse fuel with respect to the rotational speed of the classifier.

Fig. 4B is a graph showing the deposition ratio of the coarse fuel with respect to the fuel supply amount.

Fig. 4C is a graph showing the deposition ratio of the coarse fuel with respect to the flow rate of the carrier gas.

Fig. 4D is a graph showing the deposition ratio of the coarse fuel with respect to the pulverization load.

Fig. 5 is a flowchart showing a change in the operating conditions of the grinding mill.

Fig. 6 is a graph showing the swing operation of the classifier.

Description of reference numerals:

a power generation apparatus

Grinder (solid fuel crushing device)

Shell

12

Roller (crushing roller)

A drive section

Air outlet

Grader (rotary grader)

Grading blade (vane)

Fixing part

Fuel supply section

A motor

Discharge port

20

21

A transport section

A motor

A down spout (down spout) portion

30

A hot gas blower

30b

30c

30d

A state detecting part (temperature detecting unit, pressure difference detecting unit)

Bottom surface part

Top of

43.. pressure difference detecting part

A pressure gauge

43b.. upstream side detecting tube (detecting tube)

43c. downstream side detecting tube (detecting tube)

Open end 43c1

43d

An O-ring

45.. journal head

46

Support arm

Support shaft

Pressing device

A control part

Solid fuel pulverizing system

Primary air flow path (primary gas supply)

Supply flow path

200

210

A burner section

B1

Flow inside classifier

Pulverizing load L

SP1

SP2. (of a grader) exterior

SP3. (below the classifier) space

Qa.. Primary air flow (flow of carrier gas)

Qb.. fuel supply (solid fuel supply)

Classifier rotational speed (rotational speed).

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

< overall Structure of Power plant 1>

The power plant 1 of the present embodiment includes a solid fuel pulverization system 100 and a boiler 200.

The solid fuel pulverization system 100 is an apparatus that pulverizes a solid fuel such as a biomass fuel to generate a particulate fuel and supplies the particulate fuel to the burner unit 220 of the boiler 200. The power plant 1 includes one solid fuel pulverization system 100, but may include a plurality of solid fuel pulverization systems 100 corresponding to the plurality of burner units 220 of one boiler 200. In addition, although the power generation facility 1 of the present embodiment mainly uses the biomass fuel, the power generation facility may be a mixed combustion of coal and the biomass fuel.

The solid fuel pulverization system 100 includes a mill (solid fuel pulverization device) 10, a coal feeder 20, a blowing unit 30, a state detection unit 40, and a control unit 50.

In the present embodiment, the upward direction represents the direction of the vertically upper side, and the "upper" of the upper portion, the upper surface, and the like represents the portion of the vertically upper side. Similarly, "lower" indicates a vertically lower portion.

Biomass fuel is a renewable organic resource derived from living organisms, and examples thereof include, but are not limited to, wood waste, driftwood, grasses, waste, sludge, tires, and recycled fuel (pellets, chips) using them as a raw material. The size of the particles is, for example, about 6 to 8mm in diameter and about 40mm or less in length. Biomass fuel introduces carbon dioxide during the growth of biomass, and is used as carbon neutrality that does not discharge carbon dioxide as a global warming gas, and thus various studies have been made on the use thereof.

The grinder 10 includes a housing 11, a rotary table 12, rollers 13 (grinding rollers), a drive unit 14, a classifier (rotary classifier) 16, a fuel supply unit 17, and a motor 18 for driving the classifier 16 to rotate.

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

A driving unit 14 is provided near the bottom surface 41 of the housing 11, and the turntable 12 that rotates by the driving force transmitted from the driving unit 14 is rotatably disposed. The driving unit 14 is controlled by the control unit 50.

The turntable 12 is a member having a circular shape in plan view, and is disposed so as to face a lower end portion of the fuel supply portion 17. The upper surface of the turntable 12 may have, for example, an inclined shape in which the center portion is low and the height increases toward the outside, or may have an outer peripheral portion bent upward. The fuel supply unit 17 supplies solid fuel (biomass fuel in the present embodiment) from above toward the rotating table 12 below, and the rotating table 12 pulverizes the supplied solid fuel between the rotating table and the rollers 13, and is therefore also referred to as a pulverization table.

When the solid fuel is fed from the fuel supply portion 17 toward the center of the turntable 12, the solid fuel is guided and sandwiched between the outer peripheral side of the turntable 12 and the rollers 13 by the centrifugal force generated by the rotation of the turntable 12, and is pulverized. The pulverized solid fuel becomes pulverized fuel, and is entrained upward by a carrier gas (hereinafter referred to as "primary air") introduced from a primary gas supply unit (hereinafter referred to as "primary air flow path") 100a, and is guided to the classifier 16. That is, blow-out ports 15 (see fig. 2) for allowing the primary air flowing in from the primary air flow path 100a to flow out to a space above the turntable 12 in the casing 11 are provided at a plurality of locations on the outer peripheral side of the turntable 12. Blades (not shown) are provided above the air outlet 15, and impart a swirling force to the primary air blown out from the air outlet 15. The primary air to which the swirling force is applied by the paddle becomes an air flow having a swirling velocity component, and the solid fuel pulverized on the rotary table 12 is guided to the classifier 16 above in the casing 11. Most of the coarse fuel having a larger particle size than the predetermined particle size among the pulverized solid fuel mixed with the primary air is classified by the classifier 16, or falls without reaching the classifier 16, returns to the turntable 12, and is pulverized again.

The roller (pulverizing roller) 13 is a rotating body that pulverizes the solid fuel supplied from the fuel supply unit 17 to the rotating table 12. The roller 13 presses the upper surface of the turntable 12, and cooperates with the turntable 12 to crush the solid fuel. In fig. 1, only one roller 13 is representatively shown, but a plurality of rollers 13 may be arranged to face each other at a constant interval in the circumferential direction so as to press the upper surface of the rotating table 12. For example, the three rollers 13 are arranged at regular intervals in the circumferential direction at angular intervals of 120 ° in the outer circumferential portion. In this case, the three rollers 13 are equally spaced from the rotation center axis of the rotary table 12 at the portions (pressed portions) in contact with the upper surface of the rotary table 12.

The roller 13 is supported by a journal head (journal head)45 so as to be vertically swingable, and freely approaches or separates from the upper surface of the turntable 12. When the rotary table 12 rotates in a state where the outer peripheral surface of the roller 13 is in contact with the upper surface of the rotary table 12, the roller receives a rotational force from the rotary table 12 and rotates in conjunction therewith. When the solid fuel is supplied from the fuel supply portion 17, the solid fuel is pressed between the roller 13 and the turntable 12 and pulverized into pulverized fuel including fine fuel and coarse fuel.

The intermediate portion of the support arm 47 of the journal head 45 is supported by a support shaft 48 extending in the horizontal direction. That is, the support arm 47 is supported by the side surface portion of the housing 11 so as to be swingable in the roller vertical direction about the support shaft 48. A pressing device 49 is provided at an upper end portion of the support arm 47 located vertically above. 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 rotating table 12. The pressing force (i.e., the crushing load) of the pressing device 49 is controlled by the control unit 50.

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

The classifier 16 is provided at an upper portion of the housing 11, and has a hollow substantially inverted conical outer shape. The classifier 16 includes a plurality of classifying blades (vanes) 16a extending in the vertical direction at an outer peripheral position thereof. The lower end of each classifying blade 16a is fixed to the fixing portion. The classifying blades 16a are arranged in parallel at predetermined intervals (equal intervals) around the central axis of the classifier 16. The classifier 16 is a device for classifying the pulverized fuel, which is pulverized by the rollers 13 and conveyed by primary air, into coarse fuel having a particle size larger than a predetermined particle size and fine fuel having a particle size not larger than the predetermined particle size. The classifier 16 is a rotary classifier that performs classification by rotating entirely around a rotation axis in the vertical direction, and is also called a rotary classifier. A rotational driving force is applied to the classifier 16 by a motor 18. The rotation speed of the motor 18 is controlled by the control unit 50.

In the pulverized solid fuel that has reached the classifier 16, large coarse-grained fuel is knocked down by the classifying blades 16a due to the relative balance between the centrifugal force generated by the rotation of the classifying blades 16a and the centripetal force generated by the flow of the primary air, returned to the rotary table 12, and pulverized again, and fine-grained fuel is introduced into the discharge port 19 located at the ceiling portion 42 of the casing 11.

The fine particle fuel classified by the classifier 16 is discharged from the discharge port 19 to the supply flow path 100b, and is transported to the downflow process together with the primary air. The particulate fuel flowing out to the supply flow path 100b is supplied to the burner unit 220 of the boiler 200.

The fuel supply unit 17 is installed such that a lower end portion thereof extends into the housing 11 in the vertical direction so as to penetrate an upper end of the housing 11, and supplies the solid fuel, which is introduced from above, to a substantially central region of the turntable 12. The fuel supply portion 17 is supplied with solid fuel from a coal feeder 20.

The coal feeder 20 includes a bunker 21, a conveying unit 22, and a motor 23. The conveying unit 22 conveys the solid fuel discharged from the lower end portion of the blanking pipe portion 24 located directly below the bunker 21 by the driving force applied from the motor 23, and guides the solid fuel to the fuel supply unit 17 of the grinder 10.

In general, the primary air for transporting the pulverized solid fuel, i.e., the particulate fuel, is supplied to the inside of the grinder 10, and therefore, the pressure is higher than the atmospheric pressure. In the blanking pipe portion 24, which is a pipe extending in the vertical direction directly below the hopper 21, the fuel is held in a stacked state inside, and the primary air and the particulate fuel on the grinding mill 10 side are ensured to have sealing properties such that they do not flow back by the fuel layer stacked in the blanking pipe portion 24. The amount of solid fuel supplied to the grinder 10 may be adjusted by the belt speed of the belt conveyor of the conveying unit 22.

The blowing unit 30 is a device for blowing primary air (carrier gas) for drying the solid fuel pulverized by the rollers 13 and supplying the dried solid fuel to the classifier 16 into the casing 11.

The air blowing unit 30 includes a hot air blower 30a, a cold air blower 30b, a hot air damper 30c, and a cold air damper 30d in order to adjust the temperature of the primary air blown to the casing 11 to an appropriate temperature.

The hot air blower 30a is a blower that blows heated primary air supplied from a heat exchanger such as an air preheater. A hot air damper 30c is provided on the downstream side of the hot air blower 30a. The opening degree of the hot air damper 30c is controlled by the control unit 50. The flow rate of the primary air blown by the hot air blower 30a is determined according to the opening degree of the hot air damper 30c.

The cold air blower 30b is a blower that blows primary air, which is outside air at normal temperature. A cold air damper 30d is provided downstream of the cold air blower 30b. The opening degree of the cold air damper 30d is controlled by the control unit 50. The flow rate of the primary air blown by the cold air blower 30b is determined according to the opening degree of the cold air damper 30d. The flow rate of the primary air is the total flow rate of the primary air blown by the hot air blower 30a and the flow rate of the primary air blown by the cold air blower 30b, and the temperature of the primary air is determined by the mixing ratio of the primary air blown by the hot air blower 30a and the primary air blown by the cold air blower 30b and is controlled by the controller 50. Further, the oxygen concentration of the primary air flowing in from the primary air flow path 100a may be adjusted by introducing a part of the combustion gas discharged from the boiler 200, which has passed through an environmental device such as an electric dust collector via a gas recirculation fan, into the primary air blown to the hot air blower 30a to form a mixed gas.

In the present embodiment, the measured or detected data is transmitted to the control unit 50 by the state detection unit 40 of the housing 11. The state detector 40 is, for example, a differential pressure measuring means, and measures a differential pressure between a portion of the primary air flowing from the primary air flow path 100a into the grinder 10 and the discharge port 19 discharging the primary air and the particulate fuel from the grinder 10 to the supply flow path 100b as a differential pressure in the grinder 10. The increase and decrease in the circulation amount of the pulverized solid fuel circulating through the grinder 10 and the increase and decrease in the pressure difference in the grinder 10 with respect to the increase and decrease in the circulation amount of the pulverized solid fuel vary depending on the classification performance of the classifier 16. That is, since the particulate 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, a large amount of particulate fuel can be supplied to the burner unit 220 provided in the boiler 200 within a range in which the particle size of the particulate fuel does not affect the combustibility of the burner unit 220. In the present embodiment, a differential pressure detecting unit 43 is provided in addition to the differential pressure measuring means (the means for measuring the differential pressure of the grinding machine) for measuring the differential pressure between the discharge port 19 and the inside of the grinding machine 10, and this will be described with reference to fig. 2 and the following drawings.

The state detector 40 is, for example, a temperature measuring means, detects the temperature of the primary air temperature-adjusted by the blower 30 in the casing 11, and controls the blower 30 so as not to exceed the upper limit temperature, and the blower 30 blows the primary air for supplying the solid fuel pulverized by the rolls 13 to the classifier 16 into the casing 11. The primary air is cooled by drying and conveying the pulverized material in the casing 11, and therefore the temperature of the upper space of the casing 11 is, for example, about 60 to 80 ℃.

The control unit 50 is a device that controls each part of the solid fuel pulverization system 100. The control unit 50 can control the rotation of the rotating table 12 with respect to the operation of the grinding machine by transmitting a drive instruction to the drive unit 14, for example. The control unit 50 can adjust the classification performance by transmitting a drive instruction to the motor 18 of the classifier 16 and controlling the rotation speed, for example, to rationalize the pressure difference in the grinder 10 and stabilize the supply of the particulate fuel. The control unit 50 can adjust the supply amount of the solid fuel supplied to the fuel supply unit 17 by conveying the solid fuel by the conveying unit 22, for example, by transmitting a drive instruction to the motor 23 of the coal feeder 20. Further, the control unit 50 can control the flow rate and temperature of the primary air by transmitting an opening degree instruction to the air blowing unit 30 to control the opening degrees of the hot air damper 30c and the cold air damper 30d.

The control unit 50 is composed of, 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 from the RAM or the like and executes processing and arithmetic processing of information, thereby realizing various functions. The program may be installed in advance in a ROM or another storage medium, provided in a state of being stored in a computer-readable storage medium, distributed via a wired or wireless communication unit, or the like. The computer-readable storage medium refers to a magnetic disk, an optical magnetic disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

Next, a boiler 200 that generates steam by burning particulate fuel supplied from the solid fuel pulverization system 100 will be described. The boiler 200 includes a furnace 210 and a burner unit 220.

The burner unit 220 is a device that forms a flame by burning particulate fuel using primary air containing the particulate fuel supplied from the supply flow path 100b and secondary air supplied from a heat exchanger (not shown). The combustion of the particulate fuel proceeds in the furnace 210, and the high-temperature combustion gas passes through a heat exchanger (not shown) such as an evaporator, a superheater, an economizer, and the like, and is discharged to the outside of the boiler 200.

The combustion gas discharged from the boiler 200 is subjected to a predetermined treatment in an environmental device (a denitration device, an electric dust collector, and the like are not shown), is subjected to heat exchange with outside air in a heat exchanger (not shown) such as an air preheater, and is guided to a chimney (not shown) through an induction fan (not shown) to be released into the atmosphere. In the heat exchanger, the outside air heated by heat exchange with the combustion gas is sent to the hot air blower 30a.

The feed 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, which is sent to a steam turbine (not shown) to drive a generator (not shown) to rotate and generate electric power.

< pressure difference detection section >

In fig. 2, the differential pressure detecting portion 43 provided separately from the state detecting portion 40 is shown. The differential pressure detecting unit 43 detects a differential pressure different from a grinder differential pressure, which is a differential pressure between the upstream side (inside the grinder 10) and the downstream side (discharge port 19) of the grinder 10 measured by the state detecting unit 40. Specifically, the differential pressure detecting unit 43 measures a differential pressure between a pressure inside SP1 of the classifier (rotary classifier) 16 on the inner peripheral side of the classifying blade 16a and a pressure inside the casing 11 (outside SP2 of the classifier 16) on the outer peripheral side of the classifying blade 16a (hereinafter, this differential pressure is referred to as "classifier differential pressure"). More specifically, the differential pressure detecting section 43 measures the differential pressure between the upstream side (outside SP2) and the downstream side (inside SP1) of the primary air (carrier gas) flow of the classifying vanes 16a containing the pulverized fuel. As the differential pressure detecting unit 43, for example, a digital load cell 43a is used. The measurement value of the load cell 43a is sent to the control unit 50. The differential pressure detecting unit 43 is not limited to a differential pressure gauge such as a digital pressure gauge, and may be another type of differential pressure gauge, and may be provided with differential pressure gauges on the upstream side and the downstream side of the primary air flow including the pulverized fuel of the classifying blades 16a, respectively, to obtain the difference in pressure values measured by these differential pressure gauges.

The differential pressure detection unit 43 includes: an upstream side detection pipe 43b inserted from the grinder body outside side on the upstream side of the classifying paddle 16a and having one end opened; and a downstream side detection pipe 43c inserted from the grinder body outside side on the downstream side of the classifying paddle 16a and having an open end. An opening/closing valve 43d is provided between the upstream side detection tube 43b and the downstream side detection tube 43c and the load cell 43a, respectively. The opening and closing valve 43d is opened when the differential pressure is measured, and is closed when the differential pressure is not measured. When the load cell 43a is replaced, the opening/closing valve 43d is closed. The control unit 50 may control the opening and closing of the opening and closing valve 43d.

As shown in fig. 2, the lower end of each classifying blade 16a is fixed by a fixing portion 16b. The bottom of the classifier 16 including the fixing portion 16b and a space SP3 vertically below the classifier 16 are partitioned by the fixing portion 16b. Therefore, the coarse fuel (coarse particles) that has entered the inner SP1 of the classifier 16 without being classified by the classifying blades 16a is deposited upward from the fixing portion 16B as the deposited coarse fuel B1. When the deposition amount increases from below to above each of the classifying blades 16a, the deposited coarse fuel B1 blocks the effective area of the classifying blades 16a for classification, and thus the classification performance of the classifier 16 decreases. Further, when the amount of deposition of the deposited coarse fuel B1 increases from below the classifying blades 16a toward above, the pressure loss increases, and the classifier differential pressure increases upstream and downstream of the classifying blades 16a. The controller 50 monitors the pressure difference between the inside SP1 and the outside SP2 of the classifier 16 obtained by the pressure difference detector 43.

In fig. 3, the downstream side of the downstream side detection tube 43c is shown. The downstream side detection pipe 43c is inserted into the inside SP1 of the classifier 16 from the opening 42a formed in the ceiling portion 42 of the grinder 10. The downstream side detection pipe 43c is fixed to the top portion 42 of the grinder 10 in an airtight manner, for example, by a flange portion 46 into which an O-ring 44 is inserted. In fig. 3, the flange portion 46 is shown before being fixed, but the flange portion 46 is fixed by a fixing bolt (not shown) at the time of fixing. Thus, the downstream side detection tube 43c can be easily detached using the flange portion 46. Therefore, when the pressure of the SP1 in the classifier 16 does not need to be measured, the downstream side detection pipe 43c can be detached, and clogging of the downstream side detection pipe 43c by the pulverized fuel can be prevented.

The downstream side detection tube 43c is bent so that the opening end 43c1 at the distal end is directed in a direction intersecting the upstream direction of the flow F1 toward the inside of the discharge port 19 side. In the present embodiment, the flow path is formed such that the inner portion SP1 is bent in an L shape, and the open end 43c1 at the tip is directed toward the downstream side of the flow F1, i.e., toward the discharge port 19. This reduces the influence of the dynamic pressure of the flow F1 inside the classifier 16, and can accurately measure the static pressure. The direction of the open end 43c1 may be any direction as long as it is a position where the influence of the dynamic pressure of the flow F1 inside the classifier 16 can be ignored. In this case, for example, the tip of the downstream side detection tube 43c may be a straight tube that faces vertically downward.

As shown in fig. 3, a purge pipe 43e may be connected to the downstream detection pipe 43c. An air supply source, not shown, is connected to the upstream side of the purge pipe 43 e. The purge air (purge fluid) can be made to flow from the purge pipe 43e toward the open end 43c1 of the downstream side detection pipe 43c. This can prevent the downstream side detection pipe 43c from being clogged by the pulverized fuel contained in the flow F1 entering the classifier from the open end 43c1. Therefore, the purge air is not normally supplied, but is supplied when the clogging of the downstream side detection pipe 43c is detected. The purge air may be periodically supplied. As the purge fluid, an inert gas such as nitrogen may be used instead of air.

< operating conditions of the grinding mill 10 and deposited coarse fuel B1>

Fig. 4A to 4D show an increase and decrease in the deposition ratio of the deposited coarse fuel B1 in the SP1 inside the classifier 16 according to each operating condition. Fig. 4A to 4D show increase and decrease in the degree of deposition on the vertical axis as straight lines, but are not necessarily proportional, and show a tendency of increase and decrease in the degree of deposition, not the magnitude of the gradient showing increase and decrease in the degree of deposition.

Fig. 4A shows a case where the rotational speed of the classifier 16, i.e., the rotational speed R of the classifier is set as the operating condition. The classifier speed R is approximately proportional to the classifier pressure differential. That is, when the rotational speed R of the classifier is increased and the peripheral speed of the classifying blades 16a is increased, the pressure loss of the fluid in which the pulverized fuel including coarse particles passing between the classifying blades 16a and the primary air are mixed increases, and therefore, the pressure difference of the classifier increases. Therefore, when the classifier rotation speed R is reduced, the classifier differential pressure is reduced, and the flow rate of the fluid in which the pulverized fuel including coarse particles and the primary air are mixed between the classifying blades 16a is increased. This makes it possible to change the flow F1 inside the classifier 16 to suppress an increase in the amount of the deposited coarse fuel B1 and continue the discharge. Therefore, the deposition rate of the deposited coarse fuel B1 can be reduced by reducing the classifier rotation speed R from the current classifier rotation speed R0.

Fig. 4B shows a case where the fuel supply amount Qb of the solid fuel (biomass fuel) to the mill 10 is set as the operation condition. The increase in the fuel supply amount Qb increases the amount of the coarse-grain-containing pulverized fuel in the fluid in which the coarse-grain-containing pulverized fuel is mixed with the primary air, and increases the amount of the coarse-grain fuel introduced into the classifier 16, so that the degree of deposition of the deposited coarse-grain fuel B1 in the interior SP1 of the classifier 16 increases. Therefore, when the fuel supply amount Qb is decreased, the degree of deposition of the coarse fuel B1 deposited in the SP1 in the classifier 16 is decreased. Therefore, the fuel supply amount Qb can be reduced from the current fuel supply amount Qb0, and the accumulated coarse fuel B1 can be prevented from increasing and can be continuously discharged, whereby the degree of accumulation of the accumulated coarse fuel B1 can be reduced.

Fig. 4C shows a case where the operation condition is the primary air flow rate Qa supplied to the grinding machine 10. The increase in the primary air flow rate Qa reduces the degree of deposition of the coarse fuel B1 deposited in the SP1 inside the classifier 16. This is because: when the primary air flow rate Qa is increased, the amount of the coarse-grained fuel after pulverization in the fluid in which the coarse-grained fuel after pulverization is mixed with the primary air increases, but the flow rate of the flow F1 inside the classifier 16 increases so as to exceed the increase, and the discharge of the deposited coarse-grained fuel B1 is further promoted. Therefore, when the primary air flow rate Qa is increased, the degree of deposition of the coarse fuel B1 deposited in the SP1 inside the classifier 16 is decreased. Therefore, the degree of deposition of the deposited coarse fuel B1 can be reduced by increasing the primary air flow rate Qa as compared with the current primary air flow rate Qa 0.

Fig. 4D shows a case where the grinding load L, which is the load of the roller 13 against the turntable 12, is set as the operating condition. Since the increase in the grinding load L increases the ability to grind the solid fuel on the turntable 12, the amount of coarse particles in the fluid in which the ground fuel containing the coarse particles is mixed with the primary air is reduced, the amount of the coarse particles introduced into the classifier 16 is reduced, and the degree of deposition of the coarse fuel B1 deposited in the SP1 inside the classifier 16 is reduced. Therefore, when the pulverization load L is increased, the degree of deposition of the coarse fuel B1 deposited in the SP1 in the classifier 16 is decreased. Therefore, the deposition rate of the deposited coarse fuel B1 can be reduced by increasing the pulverization load L as compared with the conventional pulverization load L0.

< Change of operating conditions during operation >

Next, a control method using the above-described differential pressure detecting unit 43 will be described.

First, a method of controlling a change in operating conditions will be described.

As shown in fig. 5, after the grinder 10 starts to operate and reaches a steady operation, the differential pressure detection unit 43 constantly or periodically monitors the classifier differential pressure and starts control (step S0).

Next, the control unit 50 determines whether or not the classifier differential pressure obtained by the differential pressure detecting unit 43 exceeds a predetermined value (step S1). The predetermined value of the classifier differential pressure used here is a fixed value determined based on the test operation before the operation of the grinding mill 10, the actual performance of the same model, and the like. Alternatively, instead of the predetermined value of the classifier differential pressure, it may be determined whether or not the predetermined value of the change speed, which is the amount of change with respect to time of the classifier differential pressure, is exceeded. The predetermined change speed value is a fixed value determined based on the test operation before the operation of the grinding machine 10, the actual performance of the same model, and the like.

When the classifier differential pressure does not exceed the predetermined value, the differential pressure detecting unit 43 directly monitors the classifier differential pressure.

When the classifier differential pressure exceeds the predetermined value, the control unit 50 determines that the coarse fuel is accumulated in the classifier 16 at the SP1 or more and outputs the first signal. Based on the first signal, the control unit 50 transmits a control command (second output) for changing the operation conditions to the classifier 16, and changes the operation conditions in the order of decreasing the effect of reducing the degree of deposition of the coarse fuel B1 deposited in the internal SP1 of the classifier 16. First, the rotational speed of the classifier 16 is reduced (step S2). Thus, by changing the flow F1 in the classifier 16 by reducing the classifier differential pressure, the accumulated coarse fuel B1 can be prevented from increasing and can be continuously discharged. The amount of coarse fuel B1 deposited in the SP1 in the classifier 16 is reduced (see fig. 4A).

Then, the control unit 50 determines whether or not the classifier pressure difference obtained by the pressure difference detection unit 43 exceeds a predetermined value in step S3, in the same manner as in step S1. If the classifier pressure difference still exceeds the predetermined value, a control command (second output) for changing the operation condition is transmitted based on the first signal, and the fuel supply amount Qb, which is the supply amount of the biomass fuel to the mill 10, is reduced as a condition for making the effect of reducing the degree of deposition of the next deposited coarse fuel B1 large (step S4). This reduces the amount of fuel produced after pulverization, reduces coarse particles passing between the classifying blades 16a from the SP1 inside the classifier 16, and reduces the amount of coarse fuel B1 discharged by continuing the discharge (see fig. 4B). The step S4 may be performed simultaneously with the step S2.

Then, the control unit 50 determines whether or not the classifier pressure difference obtained by the pressure difference detection unit 43 exceeds a predetermined value in step S5, in the same manner as in step S1. If the classifier pressure difference still exceeds the predetermined value, a control command (second output) for changing the operation condition is transmitted based on the first signal, and the primary air flow rate Qa, which is the supply amount of the primary air to the grinder 10, is increased as a condition for making the effect of reducing the degree of deposition of the next deposited coarse fuel B1 large (step S6). This reduces the amount of coarse fuel B1 deposited in the SP1 inside the classifier 16 (see fig. 4C). Note that, this step S6 may be performed simultaneously with step S2 and/or step S4. However, if the primary air flow rate Qa is increased after step S4, the primary air is supplied after the coarse fuel B1 deposited in the SP1 of the classifier 16 is discharged to some extent, and therefore the auxiliary power required by the hot air blower 30a and the cold air blower 30B for supplying the primary air can be suppressed by suppressing the increase in the primary air flow rate Qa.

Then, the control unit 50 determines whether or not the classifier pressure difference obtained by the pressure difference detection unit 43 exceeds a predetermined value in step S7, in the same manner as in step S1. If the classifier pressure difference still exceeds the predetermined value, a control command (second output) for changing the operation condition is transmitted based on the first signal, and the grinding load L, which is the load of the roller 13 on the turntable 12, is increased as a condition that the effect of reducing the degree of deposition of the next deposited coarse fuel B1 is large (step S8). This reduces the amount of coarse fuel B1 deposited in the SP1 inside the classifier 16 (see fig. 4D). It is preferable to perform the operation after step S8 and steps S2 to S6 without finding an improvement in the classifier pressure difference, which is an effect of suppressing the accumulation of the accumulated coarse fuel B1. This is because the inhibition of the accumulation of the accumulated coarse fuel B1 due to the increase in the pulverization load L is slower in the time response than in other operating conditions, and also leads to an increase in the power.

When step S8 ends, the control of the series of operation condition changes ends (step S9).

< setting of operating conditions in test operation before start of operation >

The above-described change in the operating conditions of the grinding mill 10 may be used during the test operation before the operation of the grinding mill 10 is started. The control unit 50 stores each of the operation conditions obtained at the time of the test operation as an initial value in a storage unit, not shown, provided in the control unit 50. Thus, the operating condition under which the SP1 deposited coarse fuel B1 in the classifier 16 falls below the predetermined value can be set in advance before the operation. The predetermined value of the classifier differential pressure used for changing the operating conditions during operation can be determined based on the actual results of the test operation before the operation of the grinding machine 10 is started.

< swing operation of classifier 16 >

Next, the control of the swing operation performed during the operation of the grinding machine 10 will be described. This control is performed when an increase in classifier pressure difference is sensed to quickly discharge the accumulated coarse fuel B1.

As shown in fig. 6, when the classifier pressure difference exceeds a predetermined value, the control unit 50 performs a swing operation in which the classifier rotational speed R is temporarily increased in a short time and is restored to the original rotational speed again. The increase in the classifier rotational speed R is preferably 2 times or more and 10 times or less of the rotational speed before the increase. By increasing the classifier rotational speed R and increasing the centrifugal force in this way, the coarse fuel B1 deposited in the inner SP1 of the classifier 16 can be discharged from between the classifying blades 16a to the outer SP2 of the classifier 16. This can reduce the amount of the deposited coarse fuel B1 deposited in the SP1 inside the classifier 16. The coarse fuel discharged to the outside SP2 of the classifier 16 falls onto the rotary table 12 and is pulverized again.

The increase in the classifier rotation speed R is temporarily performed. Specifically, as shown in fig. 6, when the classifier rotation speed R is increased, the deposited coarse fuel B1 is reduced, while the fuel supply amount to the boiler 200 (see fig. 1) is reduced (that is, the fuel amount held by the grinder 10 is increased at the same time). Therefore, the swing operation time Δ T is set to a degree that the load of the boiler 200 varies without affecting the power generation of the plant. For example, the swing operation time Δ T is preferably 1 second or more and 10 seconds or less.

During the swing operation, purge air may be supplied to the deposited coarse fuel B1 in the interior SP1 of the classifier 16 to promote the discharge of the deposited coarse fuel B1.

Further, the swing operation described above may be performed when the grinder 10 is stopped. This can avoid a state in which coarse grains accumulate in the interior SP1 of the classifier 16 after the stop.

< effects of the present embodiment >

According to the present embodiment, the following operational effects are exhibited.

The biomass fuel pulverized by the rotary table 12 and the roller 13 is classified into coarse particles and fine particles by the classifier 16. The classified particulate fuel is discharged from a discharge port 19 connected to an internal SP1 of the classifier 16. The classified coarse fuel is returned to the outside SP2 of the classifier 16. However, there is a possibility that a part of the coarse fuel passes between the classifying blades 16a and is accumulated in a region where the airflow carrying force of the primary air is low, such as the fixed portion 16b to which each classifying blade 16a is fixed, without being discharged from the discharge port 19. When the coarse fuel is deposited on the fixing portion 16b, the lower portion of each of the classifying blades 16a is buried with the coarse fuel, and the effective area of each of the classifying blades 16a for classifying the pulverized fuel of the solid fuel is reduced, thereby degrading the classification performance. Therefore, a differential pressure detecting unit 43 that detects a differential pressure between the inside SP1 and the outside SP2 of the classifier 16 is provided. This makes it possible to detect that the lower portion of each classifying paddle 16a is filled with the coarse fuel and the pressure loss inside and outside the classifier 16 is increased, and to detect that the coarse fuel is deposited in the interior SP1 of the classifier 16.

The pressure of the interior SP1 of the classifier 16 can be detected by providing the downstream side detection pipe 43c having the open end 43c1 at one end portion of the interior SP1 inserted into the classifier 16.

The open end 43c1 of the downstream side detection tube 43c is preferably bent so as to be directed in a direction intersecting the upstream direction of the flow toward the inside SP1 on the discharge port 19 side. This reduces the influence of the dynamic pressure of the flow of SP1 inside classifier 16, and can accurately measure the static pressure.

Further, the downstream side detection tube 43c may be detached from the inner SP1 of the classifier 16 and the upstream side detection tube 43b may be detached from the outer SP2 of the classifier 16. Thus, when the pressure measurement is not necessary, the upstream side detection pipe 43b and the downstream side detection pipe 43c can be detached, and entry of pulverized fuel and the like into the detection pipes can be suppressed.

By flowing out the purge fluid (for example, air or nitrogen gas) having a flow rate that does not affect the pressure measurement from the purge pipe 43e connected to the downstream side detection pipe 43c, the purge fluid can be made to flow through the downstream side detection pipe 43c, and the pulverized fuel or the like can be prevented from entering the inside of the downstream side detection pipe 43c and clogging the same. For example, clogging can be prevented by introducing the purge fluid from the vicinity of the distal end of the downstream side detection pipe 43c and discharging the purge fluid from the distal end into the interior SP1 of the classifier 16.

The control unit 50 outputs a first signal when the classifier pressure difference obtained by the pressure difference detection unit 43 exceeds a predetermined value or exceeds a predetermined change speed value, which is the amount of change of the classifier pressure difference with respect to a predetermined time. This makes it possible to determine that coarse fuel has accumulated in the interior SP1 of the classifier 16.

The operation conditions are changed by the second signal for suppressing the accumulation of the coarse fuel at the same time as or after the accumulation of the coarse fuel in the interior SP1 of the classifier 16 is grasped by the first signal (steps S2 to S8). This can suppress accumulation and deposition of the coarse fuel deposited in the SP1 inside the classifier 16.

The classifier rotational speed R is reduced (step S2) to adjust the classification performance, thereby reducing the pressure loss of the rotating classifying blades 16a and rationalizing the differential pressure of the classifier 16. This changes the flow of the SP1 in the classifier 16, and the accumulated coarse fuel B1 is continuously discharged while suppressing an increase in the amount of accumulated coarse fuel B1, thereby reducing the amount of accumulated coarse fuel B1.

By reducing the fuel supply amount Qb of the biomass fuel supplied to the rotary table 12 (step S4), the amount of fuel produced after pulverization is reduced, the coarse fuel that has passed between the classifying blades 16a and entered the interior SP1 of the classifier 16 is reduced, the accumulated coarse fuel B1 is continuously discharged while suppressing an increase in the amount of accumulated coarse fuel B1, and the amount of accumulated coarse fuel B1 is reduced.

By increasing the flow rate Qa, which is the flow rate of the primary air flowing from the turntable 12 toward the classifier 16 (step S6), the discharge of the coarse fuel deposited in the inner SP1 of the classifier 16 can be promoted.

By increasing the grinding load L, which is the load of the roller 13 on the rotary table 12, the biomass fuel can be further finely ground. This reduces the generation of coarse fuel contained in the pulverized fuel, and reduces the amount of coarse fuel entering the SP1 inside the classifier 16, thereby preventing the coarse fuel from accumulating in the SP1 inside the classifier 16.

By sensing an increase in the classifier differential pressure, the swing operation (see fig. 6) is performed to temporarily increase the classifier rotational speed R and return to the original rotational speed again, and the centrifugal force for the coarse fuel is increased, whereby the coarse fuel B1 can be discharged from between the classifying blades 16a to the outside SP2 in the interior SP1 of the classifier 16. This can reduce the amount of coarse fuel B1 deposited in the SP1 inside the classifier 16.

In the present embodiment, the determination is made using the value of the differential pressure when the operating conditions are changed based on the detection by the differential pressure detecting unit 43, but the determination may be made based on the amount of change in the differential pressure with respect to time, that is, the rate of change in the differential pressure.

In the present embodiment, the case where only the biomass fuel is pulverized by the mill 10 has been described, but the present invention is not limited to this as the solid fuel pulverized by the mill 10, and may be other solid fuels, or may be a mixed fuel of coal and biomass fuel.

In the present embodiment, the pressure of the external SP2 of the classifier 16 is the pressure inside the housing 11 that houses the classifier 16 and is on the outer peripheral side of the classifier 16, but the present invention is not limited to this. When the change in the pressure loss of the classifying blade 16a when the pressure change in the main body of the grinding machine is small can be measured, the absolute pressure change in the classifier 16 may be measured, and as the pressure outside the classifier 16 in this case, a constant reference pressure may be used as long as the pressure in the housing 11 does not change greatly, and for example, the atmospheric pressure outside the housing 11 or the like may be used.

Claims

1. A solid fuel pulverizing apparatus, wherein,

the solid fuel pulverizer includes:

a rotating table;

a pulverization roller configured to pulverize the solid fuel between the pulverization roller and the turntable;

a rotary classifier including a plurality of blades that rotate about a rotation axis and are provided upright on a fixed portion in a circumferential direction, the rotary classifier classifying the pulverized fuel pulverized by the pulverization roller;

an outlet connected to an inner peripheral side of the plurality of vanes vertically provided in the circumferential direction, that is, an inside of the rotary classifier, and discharging the particulate fuel classified by the rotary classifier; and

and a differential pressure detection unit that detects a differential pressure between a pressure inside the rotary classifier, which is an inner peripheral side of the vane, and a pressure outside the rotary classifier, which is an outer peripheral side of the vane.

2. The solid fuel pulverizing apparatus according to claim 1,

the pressure difference detection unit includes a detection pipe that opens into the interior of the rotary classifier and is bent in a direction intersecting with an upstream direction of a flow in the interior.

3. The solid fuel pulverizing apparatus according to claim 2,

a purge pipe capable of supplying a purge fluid is connected to the detection pipe.

4. The solid fuel pulverization apparatus as recited in any one of claims 1 to 3,

the solid fuel pulverizer includes a control unit for acquiring a detection signal from the differential pressure detection unit,

the control unit outputs a first signal and determines that coarse fuel is deposited in the rotary classifier when the differential pressure obtained by the differential pressure detection unit exceeds a predetermined value or when a change amount of the differential pressure obtained by the differential pressure detection unit with respect to time exceeds a predetermined value.

5. The solid fuel pulverizing apparatus according to claim 4,

the control unit outputs a second signal for changing an operation condition to suppress the accumulation of the coarse fuel in the rotary classifier simultaneously with or after the first signal is output.

6. The solid fuel pulverizing apparatus according to claim 5,

the control unit changes the operating condition so as to reduce the rotational speed of the rotary classifier.

7. The solid fuel pulverizing apparatus according to claim 6,

the control unit changes the operating conditions so as to reduce the amount of solid fuel supplied to the turntable.

8. The solid fuel pulverizing apparatus according to claim 7,

the control unit changes the operating conditions so that the flow rate of the carrier gas flowing from the turntable toward the rotary classifier increases.

9. The solid fuel pulverizing apparatus according to claim 8,

the control unit changes the operating conditions so that a grinding load, which is a load of the grinding roller on the rotating table, is increased.

10. The solid fuel pulverizing apparatus according to claim 5,

the control unit changes the operating conditions so that the rotational speed of the rotary classifier is temporarily increased.

11. A power generation device, wherein,

the power generation facility is provided with:

the solid fuel pulverization apparatus as claimed in any one of claims 1 to 10;

a boiler that burns the solid fuel pulverized by the solid fuel pulverizer to generate steam; and

and a power generation unit that generates power using the steam generated by the boiler.

12. A method for controlling a solid fuel pulverizer, the solid fuel pulverizer comprising:

a rotating table;

a rotary classifier including a plurality of blades that rotate about a rotation axis and are provided upright on a fixed portion in a circumferential direction, the rotary classifier classifying the pulverized fuel pulverized by the pulverization roller; and

a discharge port connected to an inner peripheral side of the plurality of vanes vertically provided in the circumferential direction, that is, an inside of the rotary classifier, and discharging the particulate fuel classified by the rotary classifier,

in the control method of the solid fuel pulverizer,

a pressure difference between a pressure on an inner peripheral side of the vane, that is, inside the rotary classifier, and a pressure on an outer peripheral side of the vane, that is, outside the rotary classifier, is detected.