KR20220100828A - Solid fuel pulverizer and power plant provided with the same, and method for pulverizing solid fuel - Google Patents

Abstract

The present invention provides a solid fuel pulverizing device which is stable even if biomass fuel is used, so that pulverized fuel can be supplied to a boiler. The solid fuel pulverizing device comprises: a rotary table; a pulverizing roller pulverizing biomass fuel, which is solid fuel, and disposed in a space from the rotary table; a plurality of blades installed along the circumferential direction centered on a rotation axis; a rotary classifier classifying the biomass fuel after being pulverized by the pulverizing roller; and a control unit controlling the rotational speed of the rotary classifier. The control unit controls the rotational speed of the rotary classifier to be approximately constant throughout the operating range of the boiler to which the biomass fuel classified from the rotary classifier is supplied.

Description

Solid fuel grinding device, power plant having same, and solid fuel grinding method

The present invention relates to a solid fuel crushing device suitable for crushing biomass fuel, a power plant having the same, and a solid fuel crushing method.

BACKGROUND ART Conventionally, carbon-containing solid fuels such as coal and biomass fuels are pulverized into fine powders smaller than a predetermined particle size with a pulverizer (mill), and then supplied to a combustion device. The mill pulverizes solid fuel such as coal or biomass fuel fed into a rotary table by crushing it between a rotary table and rollers, and is supplied from the outer periphery of the rotary table through a duct in primary air, which is a carrier gas (carrier gas). Thus, the pulverized fuel in the form of fine powder is separated by a classifier having a small particle size, and is conveyed to a boiler for combustion in a combustion apparatus. In a thermal power plant, electricity is generated by generating steam by heat exchange with combustion gas produced by combustion in a boiler, and driving a turbine with the steam.

When coal is used as a carbon-containing solid fuel, as shown to patent documents 1 - 3, controlling the rotational speed of a rotary classifier is performed according to the amount of coal fed or the particle size of coal.

Japanese Patent Laid-Open No. 2001-254930 Japanese Patent Laid-Open No. 2008-232466 Japanese Patent Laid-Open No. 2001-347176

However, as carbon-containing solid fuels, biomass fuels such as woody pellets are difficult to pulverize compared to coal, and on the other hand, they have high combustibility and have properties that can be preferably burned even with a relatively large particle size. Therefore, when biomass fuel is used as a solid fuel, compared with the pulverized fuel of coal, it is supplied to the combustion apparatus provided in the boiler from the mill in the shape of about 5 to 10 times larger particle diameter.

As described above, since coal and biomass fuel have different particle diameters to be supplied to the combustion device, mills for pulverizing and classifying solid fuels have different designs for pulverizing biomass fuel and for pulverizing coal (for example, It is inherently preferable to individually design the housing shape, the rotational speed of the rotary table, the rotational speed of the rotary classifier, etc.). However, from the viewpoint of facility cost, installation space, etc., the same mill can handle both biomass fuel and coal solid fuel, and using a mill that can share the coal and biomass fuel, biomass fuel is produced. It is desired to be able to use it.

The rotary classifier employs a method of classifying by passing a pulverized fuel having a predetermined particle diameter or less between a plurality of rotating blades arranged in a circumferential direction around a rotational central axis. For this reason, since the pulverized biomass fuel has a larger particle diameter compared to the case of pulverizing coal as described above, it is difficult to pass between the blades, and it is difficult to convey the pulverized biomass fuel to a burner which is a combustion device of a boiler provided on the downstream side. In addition, the pulverized fuel of biomass fuel tends to be deposited in the gap inside the mill or in the stagnant area of the air flow, and since it has a small specific gravity and is lighter than coal, for example, the stagnant air flow occurs inside the rotary classifier and the biomass Even if the pulverized fuel of the fuel is deposited in the rotary classifier, it is difficult to remove and discharge the deposit by centrifugal force, and there is a characteristic that it is easy to accumulate in the rotary classifier.

Then, the present inventors discovered that, when pulverizing biomass fuel, it was effective to control the rotation speed of a rotary classifier in a way of thinking different from coal.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide a solid fuel crushing device capable of supplying stable and pulverized pulverized fuel to a boiler even when biomass fuel is used, a power plant having the same, and a solid fuel crushing method do.

A solid fuel pulverizing apparatus according to an aspect of the present invention includes a rotary table, a pulverizing roller for pulverizing biomass fuel between the rotary table, and pulverized biomass pulverized by pulverizing the biomass fuel by the pulverizing roller A rotary classifier for classifying fuel to select pulverized biomass fuel, and a control unit for controlling a rotation speed of the rotary classifier, wherein the control unit operates over the operating range of a boiler to which the pulverized biomass fuel is supplied. Control the rotational speed of the supply air to be approximately constant.

The pulverized biomass fuel has a larger particle size than pulverized coal fuel, which is a pulverized fuel derived from coal, and it is difficult to pass between the blades of the rotary classifier. In addition, since the pulverized biomass fuel has a small specific gravity and light weight, once it enters the rotary classifier and accumulates in the region where the airflow of the carrier gas stays, the centrifugal force acting is small, so it is difficult to accumulate and discharge in the rotary classifier. . Therefore, it is difficult to pass through the rotary classifier and transport it to the downstream boiler. For this reason, as the load of the boiler increases, if the input amount of biomass fuel is increased and the rotation speed of the rotary classifier is also increased, the supply amount of the pulverized fuel supplied from the rotary classifier to the boiler side increases to suit the load. does not Therefore, even if the load of the boiler increases, by controlling the rotary classifier at a substantially constant rotation speed, it is possible to supply the pulverized fuel suitable for the increase in the load of the boiler. Moreover, since the rotation speed of a rotary classifier can be made substantially constant and can be controlled, simple control can be implement|achieved.

Furthermore, in the solid fuel grinding apparatus according to an aspect of the present invention, the control unit controls the rotational speed of the rotary classifier to be approximately constant within the range of ±1 rpm.

Since the pulverized biomass fuel has a larger particle diameter than that of pulverized coal, it is difficult to pass between the blades of the rotary classifier, so the rotational speed of the rotary classifier is reduced. In addition, since the pulverized biomass fuel is lightweight, once it enters the rotary classifier and accumulates in the region where the airflow of the carrier gas stays, the centrifugal force acting on the pulverized biomass fuel is small, so it is accumulated in the rotary classifier and discharged. hard to be For this reason, the pulverized biomass fuel pulverized by the carrier gas is transferred to the downstream boiler by reducing the rotational speed of the rotary classifier and preventing the flow of the carrier gas from being blocked so that a region in which the air flow of the carrier gas remains does not occur. It can be easily supplied.

At this time, since the median value of the rotation speed of the rotary classifier is, for example, 10 rpm or more and 30 rpm or less, it should just be in the range used as this ±10% or less. From the control precision of the rotation speed, the rotation speed made substantially constant may be within the range of ±1 rpm from the rotation speed of the rotary classifier at the time of the lowest load operation. Therefore, if the rotation speed of the rotary classifier is controlled to be substantially constant within the range of ±1 rpm, there is no significant change in combustion conditions in the boiler.

In addition, in the solid fuel pulverization apparatus according to an aspect of the present invention, the target value of the rotational speed of the rotary classifier controlled by the control unit is the particle size of the pulverized biomass fuel required by the combustion apparatus of the boiler. is determined by

In the combustion apparatus (burner) of a boiler, in order to acquire desired combustibility, the particle size of the fine pulverized biomass fuel which can be tolerated exists. For example, if the particle size is larger than a predetermined value, the pulverized biomass fuel cannot be completely combusted in the boiler, and unburned fuel is generated. On the other hand, even if the particle size is made too small than the predetermined value, the differential pressure and power consumption of the mill increase, and thus it is useless. Then, the target value of the rotation speed of a rotary classifier was decided by the particle diameter of the pulverized biomass fuel which a burner requires. Specifically, when the rotational speed of the rotary classifier is large, pulverized biomass fuel having a relatively small particle diameter is supplied to the burner, and when the rotational speed of the rotary classifier is low, pulverized biomass fuel having a relatively large particle diameter is supplied to the combustion device. The characteristic is used to determine the rotational speed of the rotary classifier. Thereby, based on the combustion performance of a combustion apparatus, the target value of the rotation speed of the rotary classifier which can burn pulverized biomass fuel favorably in a boiler can be determined easily.

In addition, in addition to the biomass fuel pulverization mode for pulverizing the biomass fuel and supplying the pulverized biomass fuel, a coal pulverization mode for pulverizing coal as the solid fuel to supply pulverized coal, wherein the control unit comprises the biomass fuel pulverization mode The rotation speed of the rotary classifier used at the time of the mass fuel crushing mode and the rotation speed of the said rotary classifier used at the time of the said coal crushing mode are switched.

In the above solid fuel pulverizing apparatus having a coal pulverization mode in which coal is pulverized into pulverized coal, when pulverizing coal into pulverized coal, the rotational speed of a rotary classifier for coal is used, and biomass fuel pulverized and pulverized When it was set as biomass fuel, it was set as using the rotation speed of the rotary classifier for biomass fuels. Thereby, it is possible to provide a solid fuel pulverization device that can be used by converting coal and biomass fuel.

In addition, in the solid fuel pulverizing apparatus according to an aspect of the present invention, the control unit sets the rotational speed of the rotary classifier used in the biomass fuel pulverizing mode, and the rotary speed of the rotary classifier used in the coal pulverizing mode. make it smaller

Since the pulverized biomass fuel has a larger particle size and is lighter than pulverized coal fuel derived from coal, it is difficult to pass through a rotary classifier to be supplied to a downstream boiler, and conveyability is not good. Therefore, by making the rotational speed of the rotary classifier in the biomass fuel grinding mode smaller than the rotational speed of the rotary classifier in the coal grinding mode, the transportability is improved without interfering with the flow of the transporting gas, , it was decided to be more reliably supplied to the downstream combustion device.

In addition, in the solid fuel crushing apparatus according to an aspect of the present invention, in the coal crushing mode, the control unit is the rotary classifier in the operating range of the boiler in the case of a load operation smaller than the minimum load operation of the boiler. A rotation speed smaller than the rotation speed of Use the same rotation speed.

In the case of pulverizing coal, when the mill is operated with a load smaller than the minimum load of the boiler, if the same rotation speed as the rotation speed of the rotary classifier in the operating range of the boiler is used, pulverization can be passed through the rotary classifier The coal in the mill becomes too fine, and the carbon contained in the coal functions as an individual lubricant, reducing friction, and the grinding roller slips against the rotary table to generate vibration. there is a possibility that there will be no Then, in the case of coal crushing mode, when it is smaller than minimum load operation|movement, it was decided that the rotation speed of a rotary classifier is lowered|hung.

On the other hand, in the case of pulverized biomass fuel, it is not crushed excessively finely like pulverized coal, and there is little possibility that the roller slips against the rotary table like coal, so even if it is smaller than the minimum load operation of the boiler, The rotational speed of the rotary classifier was the same as the operating range of the boiler. Thereby, rotational speed control of the rotary classifier at the time of the biomass fuel grinding|pulverization mode becomes simple.

In addition, in a power plant according to an aspect of the present invention, the solid fuel grinding device according to any one of the above, the boiler for generating steam by burning the solid fuel pulverized in the solid fuel grinding device in the combustion device; and a power generation unit that generates power using the steam generated by the boiler.

Further, in the solid fuel pulverization method according to an aspect of the present invention, a pulverization roller for pulverizing a biomass fuel as a solid fuel between a rotary table and the rotary table, and the pulverization roller to pulverize the biomass fuel In the solid fuel pulverization method using a rotary classifier for classifying a pulverized biomass fuel to classify pulverized biomass fuel, the rotary classifier over the operating range of a boiler to which the pulverized biomass fuel is supplied from the rotary classifier control the rotation speed of the

Since the rotational speed of the rotary classifier is controlled to be substantially constant over the operation range of the boiler, even when biomass fuel is used, the pulverized fuel can be stably supplied to the boiler.

1 is a schematic configuration diagram showing a power plant according to an embodiment of the present invention.
2 is a graph showing a primary air supply amount with respect to a fuel supply amount.
3 is a graph showing the particle size of the pulverized biomass fuel with respect to the primary air supply.
4 is a graph showing A/F with respect to a fuel supply amount.
5 is a graph showing the rotational speed of the rotary classifier with respect to the fuel supply amount in the coal pulverization mode.
6 is a graph showing the rotational speed of the rotary classifier with respect to the fuel supply amount in the biomass fuel grinding mode.
7 is a graph showing the particle size of the pulverized biomass fuel with respect to the rotation speed of the rotary classifier.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment which concerns on this invention is described with reference to drawings.

The power generation plant 1 according to the present embodiment includes a solid fuel crushing device 100 and a boiler 200 .

The solid fuel pulverizing device 100 is, for example, a device that pulverizes a solid fuel such as coal or biomass fuel, generates pulverized fuel, and supplies it to the burner (combustion device) 220 of the boiler 200 . Although the power generation plant 1 is provided with one solid fuel crushing device 100, a plurality of solid fuel crushing devices 100 corresponding to each of the plurality of burners 220 of one boiler 200 are provided. You can do it as a system.

The solid fuel crusher 100 includes a mill (crushing unit) 10 , a coal feeder 20 , a blower (carrier gas supply unit) 30 , a state detection unit 40 , and a control unit 50 . are doing

In addition, in this embodiment, the upward direction has shown the vertical upper direction, and "upper", such as an upper part and an upper surface, has shown the vertically upper part. In addition, similarly, the "lower" has shown the part of the vertically lower side.

The mill 10 for pulverizing solid fuel such as coal or biomass fuel supplied to the boiler 200 into pulverized fuel which is pulverized solid fuel pulverizes coal and further pulverizes biomass fuel.

Here, biomass fuel is an organic resource derived from a renewable organism, for example, thinning wood, waste wood, driftwood, grasses, waste, mud, tires, and using these as raw materials. Recycled fuel (pellets or chips), etc., but is not limited to those shown here. Since biomass fuel takes in carbon dioxide in the growth process of biomass, and becomes carbon neutral which does not emit carbon dioxide used as a global warming gas, the use is examined in various ways.

The mill 10 includes a housing 11 , a rotary table 12 , a roller 13 (grinding roller), a driving unit 14 , a rotary classifier 16 , a fuel supply unit 17 , a rotary type A motor 18 for rotationally driving the classifier 16 is provided.

The housing 11 is formed in a cylindrical shape extending in the vertical direction, and is a case for accommodating the rotary table 12 , the rollers 13 , the rotary classifier 16 , and the fuel supply unit 17 .

A 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 disposed along the vertical direction at the center position of the housing 11 , and the lower end reaches the inside of the housing 11 . extension is installed.

A drive unit 14 is provided near the bottom surface 41 of the housing 11 , and a rotary table 12 that rotates by a driving force transmitted from the drive unit 14 is rotatably disposed.

The rotary table 12 is a circular member in plan view, and the lower end of the fuel supply unit 17 is disposed to face each other. The upper surface of the rotary table 12 may have, for example, a shape in which a central portion is low, an inclined shape that rises toward the outside, and an outer peripheral portion is bent upward. The fuel supply part 17 supplies solid fuel (in this embodiment, for example, coal or biomass fuel) toward the rotary table 12 below from upper direction, and the rotary table 12 turns the supplied solid fuel into a roller ( 13), it is also referred to as a grinding table by grinding.

When the solid fuel is fed from the fuel supply unit 17 toward the center of the rotary table 12 , the solid fuel is guided to the outer periphery of the rotary table 12 by centrifugal force caused by the rotation of the rotary table 12 , and the roller 13 ) and pulverized. The pulverized solid fuel is hoisted upward by the carrier gas (hereinafter referred to as "primary air") guided from the carrier gas flow path (hereinafter referred to as the "primary air flow path") 100a, and a rotary classifier ( 16) is led. That is, at a plurality of locations on the outer periphery of the rotary table 12 , there are air outlets (not shown) for discharging the primary air flowing in from the primary air flow path 100a to the space above the rotary table 12 in the housing 11 . is provided. A vane (not shown) is provided above the air outlet, and a turning force is applied to the primary air blown out from the air outlet. The primary air to which the turning force is given by the vane becomes an airflow having a turning speed component, and the solid fuel pulverized on the rotary table 12 is guided to the upper rotary classifier 16 in the housing 11 . In addition, among the pulverized materials of solid fuel mixed with primary air, those having a larger particle size than a predetermined particle size are classified by the rotary classifier 16 or fall without reaching the rotary classifier 16 and fall to the rotary table 12 ), and crushed again.

The roller 13 is a rotating body that pulverizes the solid fuel supplied to the rotary table 12 from the fuel supply unit 17 . The roller 13 is pressed against the upper surface of the rotary table 12 to cooperate with the rotary table 12 to pulverize the solid fuel.

In FIG. 1 , only one roller 13 is shown representatively, but a plurality of rollers 13 are disposed to face each other at regular intervals in the circumferential direction so as to press the upper surface of the rotary table 12 . For example, three rollers 13 are arranged at equal intervals in the circumferential direction with an angular interval of 120° on the outer periphery. In this case, the distance from the rotation center axis of the rotation table 12 becomes equidistant from the part (part to press) where the three rollers 13 contact the upper surface of the rotation table 12. As shown in FIG.

The roller 13 is swingable up and down by the journal head 45, and is supported with respect to the upper surface of the rotary table 12 so as to be approachable and spaced apart. When the rotary table 12 rotates with the outer peripheral surface in contact with the upper surface of the rotary table 12, the roller 13 receives a rotational force from the rotary table 12 and follows. 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 pulverized fuel.

The support arm 47 of the journal head 45 is supported by a support shaft 48 whose intermediate portion extends in the horizontal direction. That is, the support arm 47 is supported so as to be able to swing in the vertical direction of the roller with the support shaft 48 as the center on the side surface of the housing 11 . Moreover, the pressing device 49 is provided in the upper end part in the vertically upper side of the support arm 47. As shown in FIG. The pressing device 49 is fixed to the housing 11 and applies a load to the roller 13 via a support arm 47 or the like so as to press the roller 13 to the rotary table 12 .

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

The rotary classifier 16 is provided on the upper portion of the housing 11 and has a hollow, substantially inverted cone-shaped outer shape. The rotary classifier 16 is provided with a plurality of blades 16a extending in the vertical direction at its outer peripheral position. Each blade 16a is provided in parallel with a predetermined interval (equal spacing) around the central axis of the rotary classifier 16 . In addition, the rotary classifier 16 uses the solid fuel pulverized by the roller 13 to have a predetermined particle size (for example, 70 µm to 100 µm for coal, 0.6 mm to 1.0 mm for biomass fuel). (Hereinafter, pulverized solid fuel exceeding a predetermined particle size is referred to as "coarse fuel") and a predetermined particle size or less (hereinafter, solid fuel pulverized to a predetermined particle size or less is referred to as "pulverized fuel"). The rotary classifier 16 is provided with a rotational driving force by a motor 18 controlled by the control unit 50 .

The fuel after pulverization of the solid fuel that has reached the rotary classifier 16 has a relative balance between the centrifugal force generated by the rotation of the blade 16a and the centrifugal force caused by the airflow of the primary air. 16a), returned to the rotary table 12 and ground again, and the pulverized fuel is led to the outlet 19 at the ceiling portion 42 of the housing 11 .

The pulverized fuel classified by the rotary classifier 16 is discharged from the outlet 19 to the supply passage 100b, and is returned to the subsequent process together with the primary air. The pulverized fuel discharged into the supply passage 100b is supplied to the burner 220 of the boiler 200 .

The fuel supply unit 17 is installed so that the lower end extends to the inside of the housing 11 in the vertical direction so as to penetrate the upper end of the housing 11 . The solid fuel injected from the upper portion of the fuel supply unit 17 is supplied to an approximately central region of the rotary table 12 . Solid fuel is supplied to the fuel supply unit 17 from the coal feeder 20 .

The coal feeder 20 includes a bunker 21 , a transport unit 22 , and a motor 23 . The conveyance part 22 conveys the solid fuel discharged|emitted from the lower end of the downspout part 24 directly under the bunker 21 by the driving force provided from the motor 23. The solid fuel conveyed by the conveying unit 22 is guided to the fuel supply unit 17 of the mill 10 .

Usually, primary air for conveying the pulverized fuel which is the pulverized solid fuel is supplied to the inside of the mill 10, and the pressure is higher than atmospheric pressure. In the down spout part 24 , which is a tube extending in the vertical direction directly under the bunker 21 , fuel is held in a stacked state therein, and the solid fuel layer stacked in the down spout part 24 , , the sealing property is secured so that the primary air on the side of the mill 10 and the fuel after pulverization do not flow backwards. The supply amount of the solid fuel to be supplied to the mill 10 may be performed by adjusting the belt speed of the belt conveyor of the conveying unit 22 by the motor 23 controlled by the control unit 50 .

Chips and pellets of biomass fuel before pulverization have a constant particle size (the size of pellets is, for example, , about 6 mm to 8 mm in diameter, and about 40 mm or less in length), and is lightweight. For this reason, when biomass fuel is stored in the downspout part 24, compared with the case of coal fuel, the clearance gap formed between each biomass fuel becomes large.

Therefore, since there is a gap between the chips or pellets of the biomass fuel in the downspout unit 24, the primary air blown up from the inside of the mill 10 and the pulverized fuel pass through the gap formed between each biomass fuel, (10) There is a possibility that the internal pressure may decrease. In addition, when the primary air blows into the storage part of the bunker 21, the transportability of the biomass fuel deteriorates or dust is generated, the downspout part 24 ignites, and when the pressure inside the mill 10 decreases, the pulverized fuel There is a possibility that various problems may arise in the operation of the mill 10 , such as a decrease in the amount of conveyance. For this reason, a rotary valve (not shown) may be provided in the middle of the fuel supply part 17 from the coal feeder 20, and you may make it suppress the backflow by blowing of primary air and pulverized fuel.

The blower 30 is a device that blows primary air for supplying the solid fuel pulverized by the roller 13 to the inside of the housing 11 at the same time as drying it to the rotary classifier 16 .

The blower 30 includes a hot gas blower 30a, a cold gas blower 30b, a hot gas damper 30c, and a cold gas damper in order to adjust the primary air blown to the housing 11 to an appropriate temperature. (30d) is provided.

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 degree of the hot gas damper 30c is controlled by the control unit 50 . The flow rate of the primary air blown by the hot gas blower 30a is determined by the opening degree of the hot gas damper 30c.

The cold gas blower 30b is a blower that blows primary air that is outside air at room temperature. A cold gas damper 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 primary air is the flow rate of the sum of the flow rate of primary air blown by the hot gas blower 30a and the flow rate of primary air blown by the cold gas blower 30b, and the temperature of the primary air is The mixing ratio of the primary air blown by 30a) and the primary air blown by the cold gas blower 30b is determined and controlled by the control unit 50 .

In addition, a part of the combustion gas discharged from the boiler 200 that has passed through an environmental device such as an electric precipitator through a gas recirculation ventilator is guided to the primary air blown by the hot gas blower 30a, and is used as a mixer. , the oxygen concentration of the primary air flowing in from the primary air flow path 100a may be adjusted.

In the present embodiment, the data measured or detected by the state detection unit 40 of the housing 11 is transmitted to the control unit 50 . The state detection unit 40 of the present embodiment is, for example, a differential pressure measuring means, and a portion through which primary air flows into the mill 10 from the primary air passage 100a and a supply passage 100b from the inside of the mill 10. The differential pressure at the outlet 19 from which the furnace primary air and pulverized fuel are discharged is measured as the differential pressure in the mill 10 . For example, by the classification performance of the rotary classifier 16, the increase and decrease in the circulation amount of the pulverized solid fuel circulating in the mill 10 between the rotary classifier 16 vicinity and the rotary table 12 vicinity. The increase and decrease of the differential pressure in the mill 10 changes. That is, the solid fuel supplied to the inside of the mill 10 can be managed by adjusting the pulverized fuel discharged from the outlet 19 , so the particle size of the pulverized fuel affects the combustibility of the burner 220 . In a range not limited, a large amount of pulverized fuel may be supplied to the burner 220 provided in the boiler 200 .

In addition, the state detection part 40 of this embodiment is a temperature measuring means, for example, The primary air for supplying the solid fuel grind|pulverized by the roller 13 to the rotary classifier 16, The housing 11 Detects the temperature in the housing 11 of the primary air temperature-controlled by the blower 30 that blows inside the , and controls the blower 30 so as not to exceed the upper limit temperature. In addition, since primary air is cooled by conveying the pulverized product while drying in the housing 11, the temperature of the upper space of the housing 11 is, for example, about 60°C to 80°C.

The control unit 50 is a device for controlling each part of the solid fuel crusher 100 . The control unit 50 may control the rotational speed of the rotary table 12 with respect to the operation of the mill 10 by, for example, transmitting a driving instruction to the driving unit 14 . The control unit 50, for example, transmits a drive instruction to the motor 18 of the rotary classifier 16 to control the rotational speed, thereby optimizing the differential pressure in the mill 10 by adjusting the classification performance to differentiate it. The fuel supply can be stabilized. Further, the control unit 50 transmits a drive instruction to the motor 23 of the coal feeder 20 , for example, so that the conveying unit 22 conveys the solid fuel and supplies the solid fuel to the fuel supply unit 17 . The amount of fuel supplied can be adjusted. In addition, the control unit 50 controls the opening degree of the hot gas damper 30c and the cold gas damper 30d by transmitting the opening degree indication to the blower 30 to control the flow rate and temperature of the primary air. can

The control unit 50 is configured 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 processing for realizing various functions is, as an example, stored in a storage medium or the like in the form of a program, the CPU reads the program into RAM or the like and executes information processing and arithmetic processing, whereby various functions This is realized. The program may be installed in a ROM or other storage medium in advance, provided in a state stored in a computer-readable storage medium, or transmitted via a wired or wireless communication means, etc. 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 for generating steam by performing combustion using the pulverized fuel supplied from the solid fuel crusher 100 will be described.

The boiler 200 includes a furnace 210 and a burner 220 .

The burner 220 uses primary air including pulverized fuel (pulverized coal or pulverized biomass fuel in this embodiment) supplied from the supply flow path 100b and secondary air supplied from a heat exchanger (not shown) to heat pulverized fuel. A device that burns to form a flame. The combustion of the pulverized fuel is performed in the furnace 210 , and the high-temperature combustion gas is discharged to the outside of the boiler 200 after passing through a heat exchanger (not shown) such as an evaporator, a superheater, and an economizer.

The combustion gas discharged from the boiler 200 is subjected to predetermined processing in an environmental device (not shown, such as a denitration device, an electric dust collector, etc.), and heat exchange with the outside air is performed in a heat exchanger (not shown) such as an air preheater. and is guided to a chimney (not shown) through an induced ventilator (not shown) and discharged into the atmosphere. The outside air heated by heat exchange with combustion gas in the heat exchanger is sent to the above-mentioned hot gas blower 30a.

After the water supplied to each heat exchanger of the boiler 200 is heated in an economizer (not shown), it is further heated by an evaporator (not shown) and a superheater (not shown) to generate high-temperature and high-pressure steam, and steam as a power generation unit It is sent to a turbine (not shown) and rotationally drives a generator (not shown) to generate electricity.

[Control of primary air supply]

Next, control of the primary air supply amount (carrier gas supply amount) A supplied from the blower 30 into the mill 10 will be described. The control of the primary air supply amount A is executed by the control unit 50 based on FIG. 2 . When the mill 10 is operated, the control unit 50 mainly pulverizes coal as a solid fuel supplied to the mill 10 and supplies pulverized coal to the burner 220, and mainly pulverizes biomass fuel. It is controlled by switching the biomass fuel pulverization mode for supplying the pulverized biomass fuel to the burner 220 .

In FIG. 2, the primary air supply amount A in each of the coal grinding mode and the biomass fuel grinding|pulverization mode is shown. In the same figure, the horizontal axis indicates the fuel supply amount F (weight flow rate), and the vertical axis indicates the primary air supply amount A (weight flow rate).

On the horizontal axis, the fuel supply amount F is standardized with 1.0 as the rated operation time of the boiler 200 . In addition, as an example, the fuel supply amount F during the minimum load operation of the boiler 200 is set to 0.4, and the fuel supply amount F during the overload operation of the boiler 200 is set to 1.25. Accordingly, the operating range of the boiler 200 is 0.4 or more and 1.25 or less. In addition, the numerical values at the time of the minimum load operation and the overload operation of the boiler 200 are examples to the last, and are set in various ways depending on the boiler 200 .

In the vertical axis, the primary air supply amount (A) is normalized by setting the primary air supply amount (A1) at the time of the lowest load operation in the biomass fuel pulverization mode to 1.0.

<Coal crushing mode>

The primary air supply amount A2 in the coal pulverization mode is constant at 0.65, for example, in a region where the fuel supply amount F is smaller than 0.4 at the time of the minimum load operation, as indicated by the broken line in FIG. 2 . In addition, the value of 0.65 of the primary air supply amount A2 is an example to the last, and it means that it is smaller than the primary air supply amount A1 (ie, 1.0) in the biomass fuel grinding|pulverization mode. In addition, over the operating range from the lowest load operation to the rated operation, or over the entire operating range from the lowest load to the overload operation, the primary air supply amount (A1) used in the biomass fuel crushing mode is determined in the coal crushing mode. You may make it larger than the primary air supply amount A2 used at the time of use.

The primary air supply amount (A2) in the coal crushing mode increases until it reaches 1.25 in the overload operation when the fuel supply amount (F) during the minimum load operation becomes 0.4 or more, for example, as shown in FIG. increases monotonically. This considers the drying property which dries coal and the conveyance property which conveys coal. That is, since coal has a higher water content than biomass fuels such as woody pellets, when the fuel supply F increases, the heat of vaporization increases to obtain dryness, so it is necessary to increase the amount of primary air. In addition, when the fuel supply amount F increases, transportability is obtained, so it is necessary to increase the primary air amount.

The temperature of the primary air in the coal pulverization mode is, for example, the hot gas damper 30c and the cold gas damper 30d (see Fig. 1) by the control unit 50 near the outlet of the primary air flow path 100a. By controlling, it adjusts to 250 degreeC or more and 350 degrees C or less.

<Biomass fuel grinding mode>

The primary air supply amount A1 in the biomass fuel pulverization mode is, as shown by the solid line in FIG. 2, over the entire operating range of the boiler 200, that is, from 0.4 for the lowest load operation to 1.25 for the overload operation. Over the course of time, it is approximately constant at 1.0. The reason is as follows.

The pulverized biomass fuel has a larger particle size than pulverized coal fuel, which is a pulverized fuel derived from coal, and is difficult to pass between the blades 16a of the rotary classifier 16. making it small In addition, the pulverized fuel of the biomass fuel tends to deposit in the gaps or stagnant regions of the airflow inside the mill 10, and since the specific gravity is small and the rotational speed of the rotary classifier 16 is also set late, for example, Even if a region in which the airflow of primary air is retained is generated in the rotary classifier 16 and the pulverized fuel of biomass fuel is deposited in the rotary classifier 16, it is removed and discharged by the centrifugal force of the rotary classifier 16 it is difficult For this reason, it is necessary not to create a region in which the airflow of the primary air is retained, that is, it is necessary to sufficiently secure a conveying force based on the flow rate of the primary air, In order to secure the conveying force necessary for conveying the biomass fuel, the primary air supply amount A1 of a predetermined value or more is required. On the other hand, since biomass fuel has a low moisture content compared to pulverized coal fuel, the necessity of drying with primary air is relatively small. Therefore, even when the boiler 200 is operated under a high load such as a rated operation, it is not necessary to increase the primary air supply amount A1 in order to dry the moisture in the fuel.

In addition, the primary air supply amount A1 may just be substantially constant, and may not be strictly constant. Here, the approximately constant means, for example, the ratio of the change amount of the increase/decrease in the primary air supply amount A1 before and after the change in the increase/decrease in the fuel supply amount F corresponding to the increase/decrease in the load of the boiler 200 . What is necessary is just to be in the range used as this ±10% or less.

The temperature of the primary air in the biomass fuel pulverization mode is set lower than in the coal pulverization mode by controlling the hot gas damper 30c and the cold gas damper 30d (see FIG. 1 ) by the control unit 50 . and adjusted to, for example, 100°C or more and 150°C or less. The upper limit temperature is set not to exceed 200℃. It is because there exists a possibility of ignition of biomass fuel when it exceeds 200 degreeC. Further, for example, the moisture content of the biomass fuel of the woody pellets is dried to prevent fermentation or the like at the time of production, and is set to about 15 wt% or less.

As shown in FIG. 3 , the primary air supply amount A1 in the biomass fuel pulverization mode is determined by a static characteristic test during a trial run. Specifically, it is determined by the particle size of the pulverized biomass fuel required by the burner 220 of the boiler 200 . The target particle size d1 of the pulverized biomass fuel is determined in consideration of the following conditions, for example. When the particle size of the pulverized biomass fuel becomes large from the combustibility of the burner 220, the unburned matter may increase without being burned out by the burner 220. On the other hand, in order to reduce the particle size of the pulverized biomass fuel in order to improve the combustibility of the pulverized biomass fuel, for example, increasing the pressing force to the biomass fuel between the roller 13 and the rotary table 12, etc. It is required, and the rotational power of the rotary table 12 required for pulverization increases, and the efficiency decreases. For this reason, the target particle diameter d1 of pulverized biomass fuel is set, for example to about 0.6 mm - about 1 mm.

In FIG. 3 , the horizontal axis represents the primary air supply amount A1 , and the vertical axis represents the particle size of the pulverized biomass fuel conveyed from the mill 10 toward the burner 220 .

As shown in FIG. 3 , the target particle size d1 is determined from the combustion of the burner 220 and the rotational power of the rotary table 12 required for pulverization, and the like. Moreover, since the conveying force increases as the particle size of the pulverized biomass fuel conveyed increases the primary air supply amount A1, the conveyed particle size increases. On the other hand, as the primary air supply amount A1 is decreased, the conveying force decreases, and thus the conveyed particle size decreases. Accordingly, by increasing or decreasing the primary air supply amount A1, it is possible to obtain the primary air supply amount A1 conveyed corresponding to the target particle size d1.

In the static characteristic test at the time of a trial run, as shown in FIG. 4, A/F (primary air supply amount/fuel supply amount) is also examined.

4, A/F with respect to the fuel supply amount F is shown. In the same figure, the solid line represents the biomass fuel pulverization mode, and the dashed-dotted line represents the coal pulverization mode.

As shown in the same figure, A/F decreases as the fuel supply amount F increases also in any one at the time of the time of a coal grinding mode and the time of a biomass fuel grinding|pulverization mode. However, as shown in FIG. 2 , since the primary air supply amount (A) is higher in the biomass fuel grinding mode than in the coal grinding mode, when compared with the same fuel supply (F), the biomass fuel grinding mode is higher than the coal grinding mode. A/F is large.

When the A/F becomes large, there is a risk that the burner 220 becomes excessively air and stable combustion cannot be maintained. Therefore, the primary air supply amount (A1) in the biomass fuel pulverization mode so that A/F at the time of the fuel supply amount (F) (=0.4) at the time of the minimum load operation of the boiler 200 which becomes lean burn does not exceed the upper limit value. ) is set. The upper limit of A/F at the time of fuel supply amount F (= 0.4) is determined from the combustibility of the burner 220, and becomes 2 or more and 5 or less, for example. In addition, the primary air supply amount (A1) is taken out of the pulverized biomass fuel from the mill 10 without retaining the pulverized biomass fuel in the mill 10 even when the supply amount of the biomass fuel is maximum during overload operation. It is set to a flow rate that can be conveyed to the burner 220 . For example, as shown in FIG. 2, the primary air supply amount (A1) of the biomass fuel grinding mode at rated operation in the coal grinding mode or less is set to be higher than the primary air supply amount (A2) of the coal grinding mode, and , In the case of overload operation in the coal grinding mode, the primary air supply amount A1 in the biomass fuel grinding mode is set to the same degree as the primary air supply amount A2 in the coal grinding mode.

[Control of the rotation speed of the rotary classifier 16]

Next, control of the rotation speed of the rotary classifier 16 is demonstrated. Control of the rotation speed of the rotary classifier 16 is executed by the control unit 50 . The control unit 50 controls the operation of the mill 10 by switching between the coal grinding mode and the biomass fuel grinding mode.

The control of the rotational speed of the rotary classifier 16 is to perform the adjustment secondarily after performing the adjustment primarily by the control of the primary air supply amount A described above. Prioritizing the control of the primary air supply amount A over the rotation speed control of the rotary classifier 16 is that the primary air supply amount A is directly related to the combustion performance of the burner 220 of the boiler 200. because it affects

<Coal crushing mode>

The rotation speed control of the rotary classifier 16 in the coal grinding mode is shown by FIG. The horizontal axis represents the fuel (coal) supply amount F, and the vertical axis represents the rotational speed of the rotary classifier 16 .

On the horizontal axis, 1.0 is standardized as the fuel supply amount F during the rated operation of the boiler 200 . In addition, as an example, the fuel supply amount F during the minimum load operation of the boiler 200 is set to 0.4, and the fuel supply amount F during the overload operation of the boiler 200 is set to 1.25. Accordingly, the operating range of the boiler 200 is 0.4 or more and 1.25 or less. In addition, the numerical values at the time of the minimum load operation and the overload operation of the boiler 200 are examples to the last, and are set in various ways depending on the boiler 200 .

The vertical axis WHEREIN: It is standardized by making 1.0 the rotary classifier at the time of the minimum load operation|movement of the boiler 200 in the biomass fuel grinding|pulverization mode mentioned later.

The rotational speed of the rotary classifier 16 in the coal pulverization mode is set so that pulverized coal having a small particle size can be supplied so as to promote the classification of fine powder and coarse powder to ensure the combustibility of the burner 220 . For this reason, the rotation speed of the rotary classifier 16 in the coal crushing mode is set higher than the rotation speed (1.0) of the rotary classifier 16 in the biomass fuel crushing mode. When the fuel supply amount F is smaller than 0.4 at the time of the lowest load operation, the rotation speed of the rotary classifier 16 is set to about 5.0, and as it increases to 0.4 at the time of the lowest load operation, the rotation speed is increased to 8.0. The reason for increasing the rotational speed of the rotary classifier 16 from the low-load side to the time of the lowest-load operation in this way is as follows.

That is, in the case of a load operation smaller than the minimum load operation, if the coal is pulverized using the same rotation speed as the rotation speed 8.0 of the rotary classifier 16 during the load operation greater than the minimum load operation, the rotary classifier The coal in the mill 10 pulverized so as to pass 16 is so fine that the carbon contained in the coal functions as an individual lubricant to reduce frictional force, and the roller 13 against the rotary table 12 This is because there is a possibility that desired pulverization may not be possible due to slipping and vibrations. For this reason, in the case of a coal crushing mode, when it is smaller than minimum load operation, the rotation speed of the rotary classifier 16 is lowered|hung, and it is making into about 5.0 rotation speed in this embodiment.

From the fuel supply amount F of 0.4 to about 1.1 exceeding the rated operation 1.0, the rotational speed of the rotary classifier 16 is approximately constant at 8.0.

In addition, as shown in FIG. 2 , when the fuel supply amount F increases, the primary air supply amount A2 increases, thereby increasing the transportability of the pulverized coal, so that the pulverized coal fuel supplied to the burner 220 has a predetermined particle size. (to be able to classify), from 0.4 to 1.1, which exceeds the rated operation of 1.0, the rotation speed of the rotary classifier 16 is increased little by little as the primary air supply A2 increases, and the 220) may be made to suppress an increase in the coarse content in the pulverized coal fuel supplied.

Although the upper limit of the fuel supply amount F is 1.1 exceeding the rated operation, it may be 1.0, which is the rated operation, and is appropriately set according to the operation.

The rotational speed of the rotary classifier 16 is stable in the burner 220 of the boiler 200 from the particle size and pulverized coal flow rate of the pulverized coal supplied from the mill 10 outlet to the burner 220 in the static characteristic test during trial operation. It is determined by selecting an appropriate rotational speed at which the combustibility is obtained. The rotational speed of the rotary classifier 16 is set to, for example, 90 rpm or more and 180 rpm or less. Moreover, it is good also as control which gradually increases the rotation speed of the rotary classifier 16 with the increase of the fuel supply amount F.

During overload operation from 1.1 to 1.25 in which the fuel supply amount F exceeds the rated operation, the rotation speed of the rotary classifier 16 is not the constant rotation speed as indicated by the broken line, but the rotation speed of the rotary classifier 16 as indicated by the solid line. ) to decrease as the increase in This is to prevent the rotational power of the rotary table 12 of the mill 10 from exceeding the power specification limit of the mill 10 as the fuel supply amount F increases. That is, when the fuel supply amount F increases, the amount of the granulated fuel classified by the rotary classifier 16 increases, and the amount of falling of the granulated fuel to the rotary table 12 increases. Then, the motive power of the rotary table 12 increases and the power limit of the mill 10 is approached, so that the rotational speed of the rotary classifier 16 is reduced. Thereby, the granulated fuel also passes through the rotary classifier 16 and is conveyed to the burner 220 on the downstream side, thereby suppressing an increase in the amount of falling of the granulated fuel to the rotary table 12 . On the other hand, since the allowable level of the granulated fuel capable of maintaining the combustibility in the burner 220 is exceeded, the combustibility is reduced. The burner 220 burns by increasing the amount of granulated fuel, so that the burner 220 may slightly lower the combustibility, but the frequency of overload operation from 1.1 to 1.25 in which the fuel supply amount F exceeds the rated operation. is small and short-term, so that the power limit of the mill 10 can be prioritized and managed with little effect on the power plant 1 .

<Biomass fuel grinding mode>

In FIG. 6, rotation speed control of the rotary classifier 16 in the biomass fuel grinding|pulverization mode is shown. The horizontal axis and the vertical axis are the same as in FIG. 5 .

As shown in FIG. 6 , in the biomass fuel pulverization mode, the rotational speed of the rotary classifier 16 is approximately constant at 1.0 while the fuel supply amount F ranges from 0.4 at the lowest load to 1.25 at the overload. This is, the pulverized biomass fuel has a larger particle size than the pulverized coal fuel derived from coal, and it is difficult to pass through the blade 16a of the rotary classifier 16 . For this reason, the rotation speed of the rotary classifier 16 is set small. In addition, since the specific gravity is small, what is deposited in the stagnant region of the airflow remains in the rotary classifier and accumulates because it cannot be discharged from the rotary classifier 16 because the centrifugal force is small even when a centrifugal force is applied by the rotary classifier 16. easy to become, and it is difficult to discharge from the mill 10 through the rotary classifier 16 and from the outlet 19 . For this reason, when the input amount of biomass fuel is increased as the load operation of the boiler 200 increases, by increasing the rotational speed of the rotary classifier 16 to promote the classification of granulation, the rotary classifier 16 The supply amount of pulverized biomass fuel supplied to the boiler 200 from Only the load of 10) is likely to rise. In addition, since the rotational speed of the rotary classifier 16 in the biomass fuel pulverization mode is small, the unit required for controlling the rotational speed of the rotary classifier 16 is fine at the level of 0.1 rpm to 1 rpm to perform practical control. can't Then, even if the load of the boiler 200 increases, it was decided to supply the pulverized biomass fuel suitable for the increase of the load of the boiler 200, operating the rotary classifier 16 at a substantially constant rotation speed.

Here, the approximately constant means, for example, the increase or decrease of the rotational speed of the rotary classifier 16 before and after the change in the increase or decrease in the fuel supply amount F corresponding to the increase or decrease in the load of the boiler 200 . What is necessary is just to exist in the range used as the ratio of the change amount ±10% or less. From the control precision of the rotation speed, the rotation speed which has become substantially constant may be within the range of ±1 rpm from the rotation speed of the rotary classifier 16 at the time of the lowest load operation. That is, the rotational speed of the rotary classifier 16 in the biomass fuel grinding mode becomes substantially constant within the range of ±1 rpm, and the median value is, for example, 10 rpm or more and 30 rpm or less. In addition, the rotational speed of the rotary classifier 16 at the time of the time of a biomass fuel grinding|pulverization mode is made smaller than the time of a coal grinding mode. This is because the pulverized biomass fuel has a larger particle diameter compared to pulverized coal and it is difficult to pass between the blades 16a of the rotary classifier 16 . In addition, since pulverized biomass fuel is lighter than pulverized coal, the centrifugal force of pulverized biomass fuel to pulverized biomass fuel generated by the rotation of the blade 16a of the rotary classifier 16 is small. . For this reason, the action of the centripetal force by the airflow of the primary air becomes large, and the fine powder including the coarse powder of the pulverized biomass fuel passes between the blades 16a, and it becomes easy to enter the rotary classifier 16. At this time, if there is a stagnation of the airflow of the primary air in the rotary classifier 16, the fine powder including the coarse powder of the pulverized biomass fuel remains, but since the centrifugal force acting on the fine powder including the coarse powder of the pulverized biomass fuel is small, the rotary type It is difficult to accumulate and discharge in the classifier 16 , and it is difficult to pass through the rotary classifier 16 from the inside of the mill 10 to be supplied from the outlet 19 to the burner 220 . For this reason, the rotation speed of the rotary classifier 16 is made small, the flow of primary air is not prevented, and conveyance by primary air is accelerated|stimulated.

In the biomass fuel pulverization mode, unlike the coal pulverization mode (refer to FIG. 5 ), in the case of a load smaller than the lowest load, the rotation speed of the rotary classifier 16 is not lowered, and approximately the same rotation speed is used. This is because, in the case of biomass fuel, it is not crushed excessively like coal, and there is no possibility that the roller 13 slips with respect to the rotary table 12 like coal.

In FIG. 7, the way of thinking which determines the rotation speed made constant of the rotary classifier 16 in the biomass fuel grinding|pulverization mode is shown. In the same figure, the horizontal axis represents the rotational speed of the rotary classifier 16 , and the vertical axis represents the particle size of the pulverized fuel conveyed through the rotary classifier 16 .

The rotational speed of the rotary classifier 16 is determined by the maximum particle size of the pulverized biomass fuel required by the burner 220 of the boiler 200 . From the combustibility of the burner 220, if the particle size of the pulverized biomass fuel increases, the unburned powder increases without being burned out in the burner 220, and when it becomes smaller, the differential pressure or power consumption of the mill 10 increases. . When the target particle diameter (1.0) of the pulverized fuel is determined, the rotational speed of the rotary classifier 16 is adjusted to satisfy this target particle diameter. Specifically, as shown in FIG. 7 , if the rotational speed of the rotary classifier 16 is increased, the particle size of the pulverized biomass fuel conveyed to the subsequent process together with the primary air becomes smaller, and the rotation of the rotary classifier 16 decreases. When the speed is reduced, the rotation speed of the rotary classifier 16 is determined as an appropriate value (1.0) by using the characteristic that the particle size of the pulverized biomass fuel returned to the subsequent process together with the primary air becomes large. In the present embodiment, for example, the target particle size of the pulverized biomass fuel is set, for example, to about 0.6 mm to 1 mm.

According to this embodiment, the following effects are exhibited.

The pulverized biomass fuel has a larger particle size than pulverized coal fuel, which is a pulverized fuel derived from coal, and is difficult to pass between the blades 16a of the rotary classifier 16 . Moreover, since specific gravity is small and lightweight, in the area|region where the airflow of the carrier gas once entered the rotary classifier 16 and stayed, since the centrifugal force to the pulverized biomass fuel is small, it is hard to accumulate|store and discharge. Therefore, it is difficult to pass through the rotary classifier 16 to convey it to the downstream burner 220 and supply it. For this reason, as the load of the boiler 200 increases, when the input amount of biomass fuel is increased and the rotation speed of the rotary classifier 16 is also increased, the pulverized fuel supplied from the rotary classifier 16 to the boiler side. The amount of supply is not increased to fit the load. Therefore, even if the load of the boiler 200 increases, by controlling the rotary classifier 16 at a substantially constant rotation speed, it is possible to supply the pulverized fuel suitable for the increase in the load of the boiler 200 . Moreover, since the rotation speed of the rotary classifier 16 can be made substantially constant and can be controlled, simple control can be implement|achieved.

In the burner 220 of the boiler 200, there is an acceptable particle size of the pulverized biomass fuel in order to obtain desired combustibility. For example, if the particle size is larger than a predetermined value, the pulverized biomass fuel cannot be completely combusted in the boiler 200 and unburned fuel is generated. Then, the target value of the rotation speed of the rotary classifier 16 was decided by the particle diameter of the pulverized biomass fuel which the burner 220 requires. Thereby, based on the combustion performance of the burner 220, the target value of the rotation speed of the rotary classifier 16 which can burn the pulverized biomass fuel favorably in the boiler 200 can be easily determined.

When pulverizing coal into pulverized coal, the rotation speed of the rotary classifier 16 for coal is used, and when pulverizing biomass fuel to obtain pulverized biomass fuel, the rotary classifier 16 for biomass fuel It was decided that rotation speed was used. Thereby, it is possible to provide the solid fuel pulverization apparatus 100 that can be used by converting coal and biomass fuel.

Since the pulverized biomass fuel has a larger particle size and is lighter in weight than pulverized coal fuel derived from coal, it is difficult to pass through the rotary classifier 16 to be supplied to a downstream boiler, and conveyability is not good. Then, by making the rotational speed of the rotary classifier 16 at the time of a biomass fuel grinding|pulverization mode smaller than the rotational speed of the rotary classifier 16 at the time of a coal grinding mode, inhibiting the flow of carrier gas By improving the transportability without the need, it can be more reliably supplied to the combustion apparatus in the wake.

In the case of pulverizing coal, in the case of operating the mill 10 with a load smaller than the lowest load of the boiler 200 , the rotation speed equal to the rotation speed of the rotary classifier 16 in the operating range of the boiler 200 . When coal is pulverized using With respect to (12), there is a possibility that the desired pulverization cannot be performed, for example, the roller 13 slips and generates vibration. Then, as shown in FIG. 5, in the case of coal grinding mode, when it is smaller than minimum load operation|movement, it was decided that the rotation speed of the rotary classifier 16 was made low.

On the other hand, in the case of pulverized biomass fuel, it is not crushed excessively finely like pulverized coal, and there is little possibility that the roller 13 slips with respect to the rotary table 12 like coal, so the boiler 200 Even when it is smaller than the minimum load operation of the rotary classifier 16, the rotation speed of the rotary classifier 16 was the same as the operation range of the boiler 200 (see FIG. 6). Thereby, rotational speed control of the rotary classifier 16 at the time of the biomass fuel grinding|pulverization mode becomes simple.

1: power plant 10: wheat
11: housing 12: rotary table
13: roller (grinding roller) 14: driving part
16: rotary classifier 16a: blade
17: fuel supply unit 18: motor
19: exit 20: coal feeder
21: bunker 22: transfer unit
23: motor 24: down spout part
30: blower (carrier gas supply) 30a: hot gas blower
30b: cold gas blower 30c: hot gas damper
30d: cold gas damper 40: state detection unit
41: bottom 42: ceiling
45: journal head 47: support arm
48: support shaft 49: pressure device
50: control unit 100: solid fuel crushing device
100a: primary air flow path 100b: supply flow path
200: boiler 210: brazier
220: burner (combustion device) A: primary air supply
A1 : Primary air supply (in biomass fuel grinding mode)
A2: Primary air supply (in coal grinding mode)
d1 : target maximum particle size (of biomass fuel) F : fuel supply

Claims (8)

rotary table,
a pulverizing roller for pulverizing biomass fuel between the rotary table and;
A rotary classifier for classifying the pulverized biomass fuel obtained by pulverizing the biomass fuel by the pulverizing roller to select the pulverized biomass fuel;
and a control unit for controlling the rotation speed of the rotary classifier,
The control unit controls the rotational speed of the rotary classifier to be approximately constant regardless of the increase or decrease in the load of the boiler in the entire operating range from the lowest load to the overload operation of the boiler to which the pulverized biomass fuel is supplied.
Solid fuel crusher. The method of claim 1,
The control unit controls the rotation speed of the rotary classifier to be approximately constant within the range of ±1 rpm.
Solid fuel crusher. 3. The method of claim 1 or 2,
The target value of the rotation speed of the rotary classifier controlled by the control unit is determined by the particle size of the pulverized biomass fuel required by the combustion device of the boiler.
Solid fuel crusher. 3. The method of claim 1 or 2,
In addition to the biomass fuel pulverization mode for supplying the pulverized biomass fuel by pulverizing the biomass fuel, a coal pulverization mode for pulverizing coal to supply pulverized coal,
The control unit is configured to switch the rotational speed of the rotary classifier used in the biomass fuel crushing mode and the rotational speed of the rotary classifier used in the coal crushing mode
Solid fuel crusher. 5. The method of claim 4,
The control unit makes the rotational speed of the rotary classifier used in the biomass fuel crushing mode smaller than the rotational speed of the rotary classifier used in the coal crushing mode
Solid fuel crusher. 5. The method of claim 4,
The control unit is
In the coal grinding mode, in the case of a load operation smaller than the minimum load operation of the boiler, a rotation speed smaller than the rotation speed of the rotary classifier in the operation range of the boiler is used,
In the biomass fuel pulverization mode, in the case of a load operation smaller than the minimum load operation of the boiler, a rotation speed approximately equal to the rotation speed of the rotary classifier in the operation range of the boiler is used.
Solid fuel crusher. The solid fuel grinding device according to claim 1 or 2,
the boiler to generate steam by burning the solid fuel pulverized in the solid fuel pulverizing device;
Having a power generation unit that generates power using the steam generated by the boiler
power plant. rotary table,
a pulverizing roller for pulverizing biomass fuel, which is a solid fuel, between the rotary table;
In the solid fuel pulverization method using a rotary classifier for classifying pulverized biomass fuel by classifying pulverized biomass fuel pulverized by the pulverizing roller,
In the entire operating range from the lowest load to the overload operation of the boiler to which the pulverized biomass fuel is supplied from the rotary classifier, the rotational speed of the rotary classifier is controlled to be approximately constant regardless of the increase or decrease in the load of the boiler
Solid fuel grinding method.

Images