JP2019007631A - Solid fuel crushing device and control method of solid fuel crushing device - Google Patents

Abstract

To prevent ignition of fine powder fuel in a housing by simple control, while suppressing deterioration of combustion efficiency of a boiler.SOLUTION: A solid fuel crushing device 100 includes: a rotary table 12; a roller 13 for crushing a solid fuel; a classification part 16 for classifying the crushed solid fuel; a housing 11; a blower part 30 for delivering primary air for supplying the crushed solid fuel to the classification part 16 to the inside of the housing 11; a temperature detection part 40 for detecting the temperature of the primary air in the housing 11; and a control part 50 for setting an upper limit temperature beforehand which manages the temperature detected by the temperature detection part 40, and controls the blower part 30 so as not to exceed the upper limit temperature. The control part 50 sets a first temperature T1 as an upper limit temperature when O/C is smaller than a predetermined value P, and sets a second temperature T2 lower than the first temperature T1 when O/C is equal to or greater than the predetermined value P.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid fuel pulverizer and a control method for the solid fuel pulverizer.

2. Description of the Related Art Conventionally, a pulverizer is known in which a solid fuel such as coal is pulverized to be pulverized into fine powder having a particle size smaller than a predetermined particle size and supplied to a combustion apparatus such as a boiler (see, for example, Patent Document 1).
In Patent Document 1, when the concentration of carbon monoxide and / or carbon dioxide is measured at the outlet of a pulverizer, it is determined that an oxidation reaction of fuel, which is a sign of ignition, is occurring, and coal having a low ignition temperature It is disclosed that the ignition temperature of the solid fuel mixed with a plurality of types is increased by reducing the supply amount of the fuel to prevent ignition in the pulverizer.

JP 2011-240250 A

  However, in Patent Document 1, the concentration of carbon monoxide and / or carbon dioxide is measured at the exit of the pulverizer in order to determine a sign of ignition. Therefore, a sensor that measures the concentration of carbon monoxide and / or carbon dioxide is required. Moreover, in patent document 1, in order to change dynamically the supply_amount | feed_rate of coal with low ignition temperature according to the measured value of the density | concentration of carbon monoxide and / or carbon dioxide, it is pulverized coal supplied to a boiler etc. from a grinder. The properties of will change. Therefore, pulverized coal having a certain property cannot be stably supplied to the boiler or the like, and the combustion efficiency of the boiler or the like is fluctuated or lowered.

  The present invention has been made in view of such circumstances, and it is easy to ignite the pulverized fuel inside the housing of the pulverizer while suppressing a decrease in combustion efficiency of a boiler or the like to which the pulverized fuel is supplied. An object of the present invention is to provide a solid fuel pulverization apparatus that can be prevented by control and a control method thereof.

In order to solve the above problems, the present invention employs the following means.
The solid fuel pulverization apparatus of the present invention pulverizes the solid fuel and supplies it to the combustion apparatus, and pulverizes the solid fuel supplied to the rotary table by the rotation table rotated by the driving force from the drive unit. A roller that classifies the solid fuel crushed by the roller into finely pulverized fuel having a particle size smaller than a predetermined particle size, a housing that houses the rotary table, the roller, and the classification unit, and pulverized by the roller A blower that blows primary air for supplying the solid fuel to the classification unit into the housing, a temperature detection unit that detects a temperature of the primary air in the housing, and the temperature detection unit. A control unit that sets an upper limit temperature for managing the temperature to be detected in advance and controls the air blowing unit so as not to exceed the upper limit temperature, and the control unit includes the upper limit temperature The first temperature is set when the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel is smaller than a predetermined value, and the ratio is higher than the first temperature when the ratio is equal to or higher than the predetermined value. Set a low second temperature.

  According to the solid fuel pulverization apparatus of the present invention, when the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel (hereinafter referred to as O / C) is smaller than a predetermined value, the upper limit temperature of the primary air is set. When the first temperature is set and O / C is equal to or higher than a predetermined value, a second temperature lower than the first temperature is set. Therefore, when pulverizing a solid fuel having an O / C greater than a predetermined value and a low ignition temperature, the upper limit temperature is set low and the pulverized fuel is prevented from igniting. In addition, since the control unit sets only two types as the upper limit temperature, the first temperature when O / C is smaller than a predetermined value and the second temperature when O / C is larger than the predetermined value. Can prevent ignition of the pulverized fuel.

  Further, the solid fuel pulverization apparatus of the present invention can control the temperature detection unit to be managed without changing the property of the solid fuel even when pulverizing the solid fuel whose O / C is larger than a predetermined value and whose ignition temperature is low. Since it is sufficient to select a second temperature lower than the first temperature, it is possible to stably supply finely pulverized fuel having a certain property to a combustion apparatus such as a boiler and suppress a decrease in combustion efficiency of the boiler or the like. it can.

  Here, only two types of the first temperature and the second temperature are set as the upper limit temperature. This is because the inventors have obtained new knowledge that when the O / C of the solid fuel becomes a predetermined value or more, the pulverized fuel is likely to undergo a natural oxidation temperature rise, and the ignitability is rapidly increased. Since pulverized fuel contains moisture by adsorbing moisture on the surface, the amount of latent heat to evaporate the moisture and the sensible heat to raise the pulverized fuel to the ignition temperature are necessary to ignite the pulverized fuel. The amount of heat is required. And when there was heating from the circumference, it decided to evaluate the ignitability with respect to the predetermined calorie | heat amount thrown into pulverized fuel.

  When the O / C is smaller than the predetermined value, even if a part of the pulverized fuel reaches the ignition temperature due to the spontaneous oxidation temperature rise, the amount of heat for the latent heat that evaporates the water is until the ignition of the pulverized fuel. More than heat. Therefore, it is presumed that the water in the surrounding pulverized fuel does not sufficiently evaporate, and the surrounding pulverized fuel does not reach the ignition temperature. On the other hand, when O / C is a predetermined value or more, when a part of the pulverized fuel reaches the ignition temperature due to the spontaneous oxidation temperature rise, the amount of heat until the pulverized fuel is ignited compared to the amount of heat of the latent heat. There are many. Therefore, it is speculated that the moisture of the surrounding pulverized fuel can be sufficiently evaporated and the surrounding pulverized fuel can be raised to the ignition temperature. That is, two kinds of upper limit temperatures can be set depending on whether or not the ignition temperature is reached in a heating state obtained by subtracting the latent heat of moisture of the pulverized fuel from O / C of the solid fuel.

  In the solid fuel pulverization apparatus of the present invention, the temperature detection unit may detect a temperature of an outlet from which the pulverized fuel is discharged from the housing. The outlet from which the pulverized fuel is discharged from the housing is a portion after the solid fuel is pulverized and further classified, and is a portion directly related to the ignitability of the pulverized fuel. For this reason, it is even more appropriate to control the air blower so that the upper limit temperature is not exceeded by detecting the temperature at the outlet, even within the temperature inside the housing, which reliably prevents ignition of pulverized fuel inside the housing. can do.

  In the solid fuel pulverization apparatus having the above configuration, the first temperature may be higher than 70 ° C. and 85 ° C. or lower, and the second temperature may be 55 ° C. or higher and 70 ° C. or lower. According to the knowledge obtained by the inventors, by setting the first temperature and the second temperature in this way, the ignition of the pulverized fuel inside the housing with respect to the predetermined value of O / C of the solid fuel is further improved. It can be surely prevented. Therefore, ignition of the pulverized fuel inside the housing can be prevented by simple control while suppressing a decrease in combustion efficiency of the boiler or the like.

In the solid fuel pulverization apparatus of the present invention, the air blowing section includes a first air blowing section that blows hot air heated by a heater, and a second air blowing section that blows cold air having a temperature lower than that of the hot air. And the control unit may control a temperature of the primary air blown to the housing by adjusting a blowing amount of at least one of the first blowing unit and the second blowing unit. .
By doing in this way, a control part adjusts at least any one of the ventilation volume of the hot air which a 1st ventilation part blows, and the ventilation volume of the cold air which a 2nd ventilation part ventilates, and the temperature of primary air is an upper limit. The temperature can be controlled not to exceed.

  In the solid fuel crusher of the present invention, the predetermined value may be not less than 0.1 and not more than 0.25. The knowledge obtained by the inventors is that the ignitability of the pulverized fuel rapidly increases when O / C becomes larger than any predetermined value of 0.1 or more and 0.25 or less. Therefore, by setting the predetermined value to 0.1 or more and 0.25 or less, it is possible to prevent the ignition of the pulverized fuel inside the housing by simple control.

  According to the control method of the solid fuel pulverization apparatus of the present invention, the solid fuel pulverization apparatus that pulverizes the solid fuel and supplies the solid fuel to the combustion apparatus includes: a rotary table that rotates by a driving force from a drive unit; A roller for pulverizing the supplied solid fuel, a classification unit for classifying the solid fuel pulverized by the roller into finely pulverized fuel smaller than a predetermined particle size, and the rotary table, the roller, and the classification unit are accommodated. A housing and a blower that blows primary air into the housing for supplying the solid fuel crushed by the roller to the classification unit, and detects the temperature of the primary air in the housing A temperature detection step to be performed, and an upper limit temperature for managing the temperature detected by the temperature detection step is set in advance, and the blower unit does not exceed the upper limit temperature. A control step of controlling and a setting step of setting the upper limit temperature, wherein the setting step has a ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel as the upper limit temperature is smaller than a predetermined value In this case, a first temperature is set, and a second temperature lower than the first temperature is set when the ratio is not less than the predetermined value.

  According to the control method of the solid fuel pulverization apparatus of the present invention, ignition of the pulverized fuel inside the pulverizer housing is prevented by simple control while suppressing a decrease in combustion efficiency of a boiler or the like to which the pulverized fuel is supplied. be able to.

  According to the present invention, a solid fuel pulverization apparatus capable of preventing ignition of pulverized fuel inside a housing of a pulverizer by simple control while suppressing a decrease in combustion efficiency of a boiler or the like to which pulverized fuel is supplied. The control method can be provided.

It is a lineblock diagram showing a solid fuel crusher and a boiler of one embodiment of the present invention. It is a figure which shows the upper limit temperature of the mill exit with respect to O / C. It is a flowchart which shows the process which a control part performs.

Hereinafter, an embodiment of a solid fuel crusher and a control method thereof according to the present invention will be described with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
The solid fuel pulverization apparatus 100 according to the present embodiment is an apparatus that pulverizes solid fuel such as coal, generates pulverized fuel, and supplies it to the burner unit (combustion device) 220 of the boiler 200.
The solid fuel crusher 100 of this embodiment includes a mill 10, a coal feeder (fuel supply unit) 20, a blower unit 30, a temperature detection unit 40, and a control unit 50.
In the present embodiment, “upper” indicates the vertical upper side direction, and “upper” such as the upper portion and the upper surface indicates the upper vertical portion.

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

  The turntable 12 is a circular member in plan view that is rotated by a driving force transmitted from the drive unit 14 via the drive shaft 15, and a solid fuel (for example, coal in the present embodiment) is supplied from the fuel supply unit 17. . At a plurality of locations on the outer peripheral side of the turntable 12, air outlets (not shown) through which primary air flowing from the primary air flow path 100 a flows out into the space above the turntable 12 in the housing 11 are provided. A vane (not shown) is installed above the air outlet and applies a turning force to the primary air blown out from the air outlet. The primary air to which the turning force is applied by the vanes becomes an air flow having a turning speed component, and guides the solid fuel crushed on the rotary table 12 to the upper classification unit 16 in the housing 11. Of the pulverized solid fuel mixed with the primary air, those larger than the predetermined particle size are classified by the classifying unit 16 or dropped to the rotary table 12 without reaching the classifying unit 16. .

  The roller 13 is a rotating body that pulverizes the solid fuel supplied from the fuel supply unit 17 to the rotary table 12. The roller 13 is pressed against the upper surface of the turntable 12 and pulverizes the solid fuel in cooperation with the turntable 12. In FIG. 1, only one roller 13 is shown, but a plurality of rollers 13 are arranged 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 on the outer peripheral portion with an angular interval of 120 °. In this case, the portions where the three rollers 13 are in contact with the upper surface of the turntable 12 (the portions to be pressed) are equidistant from the center of the turntable 12.

The drive unit 14 is a device that transmits a driving force to the rotary table 12 via the drive shaft 15 and rotates the rotary table 12 around the central axis.
The classifying unit 16 has a solid fuel pulverized by the roller 13 larger than a predetermined particle size (for example, 70 to 100 μm) (hereinafter, pulverized solid fuel exceeding the predetermined particle size is referred to as “coarse powder fuel”). This is an apparatus for classifying a pulverized solid fuel having a predetermined particle diameter or less into a pulverized solid fuel having a predetermined particle diameter or less (hereinafter referred to as “finely pulverized fuel”). The classifying unit 16 has, for example, a truncated cone shape, is attached to the upper side of the housing 11 along the cylindrical axis of the substantially cylindrical housing 11, and includes a plurality of classifying blades on the outer peripheral side. The classifying unit 16 is given a driving force by a motor 18 and rotates around the cylindrical axis of the housing 11.

The pulverized product of the solid fuel that has reached the classification unit 16 guides the coarse powder fuel to the rotary table 12 by a relative balance between the centrifugal force generated by the rotation of the classification blade and the centripetal force caused by the air flow of the primary air, and the fine powder fuel ( In this embodiment, for example, pulverized coal fuel) is guided from the housing 11 to the outlet 19.
The pulverized fuel classified by the classification unit 16 is discharged from the outlet 19 to the supply channel 100b. The pulverized fuel that has flowed out to the supply channel 100 b is supplied to the burner unit 220 of the boiler 200.

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

  The coal feeder 20 includes a hopper 21, a transport unit 22, and a motor 23. The transport unit 22 transports the solid fuel discharged from the lower end portion of the hopper 21 by the driving force applied from the motor 23 and guides it to the fuel supply unit 17 of the mill 10.

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

  The hot gas blower 30a is a blower that blows heated primary air supplied from a heat exchanger (heater) such as an air preheater. A hot gas damper (first air blower) 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 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 ambient air. A cold gas damper (second air blower) 30d is provided on the downstream side of the cold gas blower 30b. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The flow rate of the primary air blown by the cold gas blower 30b is determined by the opening degree of the cold gas damper 30d. The flow rate of the primary air is the sum of the flow rate of the primary air blown by the hot gas blower 30a and the flow rate of the primary air blown by the cold gas blower 30b, and the temperature of the primary air is the primary air blown by the hot gas blower 30a. Is determined by the mixing ratio of the primary air blown by the cold gas blower 30b and controlled by the control unit 50.

  The temperature detection unit 40 is a sensor that detects the temperature of the outlet 19. The temperature detector 70 detects the temperature of the pulverized fuel discharged from the outlet 19 and outputs it to the controller 50.

  The control unit 50 is a device that controls each part of the solid fuel crusher 100. The control unit 50 controls the number of rotations of the turntable 12 by transmitting a drive instruction to the drive unit 14. Further, the control unit 50 can adjust the solid fuel supply amount that the transport unit 22 transports the solid fuel and supplies to the fuel supply unit 17 by transmitting a drive instruction to the motor 23 of the coal feeder 20. . Moreover, the control part 50 can control the flow volume and temperature of primary air by transmitting the opening degree instruction | indication to the ventilation part 30, and controlling the opening degree of the hot gas damper 30c and the cold gas damper 30d.

Next, a description will be given of the boiler 200 that performs combustion using the pulverized fuel supplied from the solid fuel crusher 100 to generate steam.
The boiler 200 includes a furnace 210 and a burner unit 220.

  The burner unit 220 is a device that burns the pulverized fuel using primary air containing the pulverized fuel supplied from the supply flow path 100b and secondary air supplied from a heat exchanger (not shown). 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 by an environmental device such as a denitration device, and is sent to a heat exchanger (heater; not shown) such as an air preheater to exchange heat with the outside air. . The outside air heated by heat exchange with the combustion gas in the heat exchanger is sent to the above-described hot gas blower 30a.
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. Power is generated by being sent to a turbine (not shown) and rotationally driving a generator (not shown).

Next, a method for preventing the pulverized fuel from igniting inside the housing 11 by simple control will be described.
As described above, the mill 10 pulverizes the solid fuel inside the housing 11 and dries the pulverized fuel with the primary air. The solid fuel such as coal pulverized by the mill 10 contains moisture. Therefore, the moisture contained in the pulverized fuel evaporates by being heated by the primary air heated to a predetermined temperature. And if the water | moisture content contained in pulverized fuel evaporates to some extent, it will become easy to discharge | release volatile matters, such as combustible gas, from pulverized fuel. Therefore, in order to prevent the pulverized fuel from igniting inside the housing 11, it is important to appropriately control the temperature inside the housing 11.

  In addition, it is known that the ignition temperature of solid fuels such as coal decreases as the O / C, which is the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel, increases. Then, the inventors conducted a test using a plurality of types of coal having different O / C, and when the O / C becomes larger than a predetermined value, the ignitability of the pulverized fuel rapidly increases. Obtained knowledge. Based on this new knowledge, it is determined that it is appropriate to set the upper limit temperature reaching the ignition temperature in two types for cases where the O / C value is less than or equal to the predetermined value of the solid fuel. I came to get.

  Here, the coal used for the test by the inventors is bituminous coal (high volatility A), bituminous coal (high volatility B), bituminous coal (high volatility B) classified by D388 established by ASTM (American Society for Testing and Materials). High volatility C), subbituminous coal A, subbituminous coal B, subbituminous coal C and the like. The value of O / C is the ratio of the number of oxygen atoms to the number of carbon atoms in a dry state where the coal does not contain moisture, and is obtained separately for each coal type. Therefore, the number of oxygen atoms in O / C does not include the number of oxygen atoms in water contained or adsorbed in the solid fuel pulverized by the mill 10.

  According to the tests conducted by the inventors, when the above-mentioned coal is used as the solid fuel, the ignitability of the pulverized fuel increases rapidly when the O / C is in the range of 0.10 to 0.25. It was found that a predetermined value P of O / C exists. Here, the case where the ignitability is high means a case where the ignition temperature at which the pulverized fuel reaches ignition is low. The inventors measured the temperature (the temperature corresponding to the outlet 19) at which the pulverized fuel is ignited by increasing the temperature of the air mixed with the pulverized fuel in an environment in which the pulverized fuel is approximated to the inside of the mill 10. As a result, it was found that when the O / C is smaller than the predetermined value P, the pulverized fuel may be ignited in a temperature range where the temperature corresponding to the outlet 19 exceeds 70 to 85 ° C. On the other hand, it has been found that when the O / C is equal to or greater than the predetermined value P, the pulverized fuel may be ignited in a temperature range where the temperature corresponding to the outlet 19 exceeds 55 to 70 ° C.

  It is more preferable to use the temperature of the outlet 19 among the temperatures in the housing 11 as the temperature at which the pulverized fuel reaches ignition. This is because the outlet 19 is a portion after the solid fuel is further classified after pulverization, and the concentration of the fine fuel suitable for the downstream burner 220 is high, and it is directly related to the ignitability of the fine fuel. This is because it is a related part. On the other hand, the temperature of the inlet that becomes the space above the rotary table 12 among the temperatures in the housing 11 is the high temperature primary air that has flowed in from the primary air flow path 100 a flows out into the space above the rotary table 12 in the housing 11. Then, heat is taken away by the drying of the solid fuel and the pulverized fuel, and then the temperature decreases quickly. Therefore, the temperature inside the housing 11 is represented by the inlet temperature, or the ignitability of the pulverized fuel is determined. Is unsuitable. That is, the temperature of the outlet 19 is preferable because it can be approximated to the internal temperature of the housing 11 and the temperature can be easily measured.

  As described above, the reason why the predetermined value P of O / C at which the ignitability of the pulverized fuel rapidly increases is presumed to be as follows. Since pulverized fuel contains moisture by adsorbing moisture on its surface, the amount of latent heat that evaporates the moisture and the amount of sensible heat that raises the pulverized fuel to the ignition temperature are necessary to ignite the pulverized fuel. Is required. Then, when the pulverized fuel is heated from the surroundings, the ignitability with respect to a predetermined amount of heat input to the pulverized fuel is evaluated.

  When O / C is smaller than the predetermined value P, even if a part of the pulverized fuel reaches the ignition temperature due to the spontaneous oxidation temperature rise, the heat quantity of the latent heat that evaporates the water is the calorific value due to the ignition of the pulverized fuel. More than Therefore, it is presumed that the water in the surrounding pulverized fuel does not sufficiently evaporate, and the surrounding pulverized fuel does not reach the ignition temperature. On the other hand, when O / C is equal to or greater than the predetermined value P, when a part of the pulverized fuel reaches the ignition temperature due to the spontaneous oxidation temperature rise, the amount of heat until the pulverized fuel is ignited compared to the amount of heat of the latent heat. There are many. Therefore, it is presumed that the water in the surrounding pulverized fuel is sufficiently evaporated and the surrounding pulverized fuel is raised to the ignition temperature. That is, with respect to the solid fuel O / C, it is divided into two types of upper limit temperatures depending on whether or not the ignition temperature is reached in a state where the latent heat of moisture of the pulverized fuel is subtracted from a predetermined amount of heat input to the pulverized fuel. It can be determined that the setting is good. At this time, the O / C corresponding to whether or not the ignition temperature is reached is a predetermined value P.

  The solid fuel pulverization apparatus 100 of the present embodiment is based on the upper limit temperature of the outlet 19 of the mill 10 with respect to the O / C shown in FIG. It controls the upper limit of temperature. In this embodiment, as shown in FIG. 2 as an example, the upper limit temperature (first temperature) T1 when O / C is smaller than a predetermined value P is set to a temperature set from 70 to 85 ° C. not including 70 ° C., By controlling the upper limit temperature (second temperature) T2 when O / C is equal to or higher than a predetermined value from 55 to 70 ° C., ignition of pulverized fuel inside the housing 11 is prevented by simple control. It is.

  In the present embodiment, the O / C value of the solid fuel used as fuel in the solid fuel crusher 100 is separately analyzed by, for example, analyzing the gas component that has been heated and burned in advance using an element concentration analyzer. It shall be calculated in advance. Further, in the present embodiment, the value of each O / C and the finely pulverized fuel obtained by pulverizing each solid fuel are ignited for a plurality of types of solid fuel (for example, coal coal type) used in the solid fuel pulverization apparatus 100. The test result of the temperature to reach (the temperature corresponding to the outlet 19) is obtained, and by arranging the test result in a graph as shown in FIG. 2, the ignitability of the pulverized fuel rapidly increases. It is assumed that a predetermined value P is obtained.

  Here, the process which the solid fuel crusher 100 of this embodiment performs is demonstrated using the flowchart shown in FIG. FIG. 3 is a flowchart illustrating processing executed by the control unit 50. The control unit 50 executes each process shown in FIG. 3 by executing a program stored in a storage unit (not shown).

  In step S301 in FIG. 3, the control unit 50 reads and sets a predetermined value P obtained in advance from a test from a storage unit (not shown). As described above, according to the tests conducted by the inventors, in a range where O / C is 0.10 or more and 0.25 or less, the ignitability of the pulverized fuel increases rapidly. Was found to exist. Therefore, the control unit 50 stores a value in a range of 0.10 or more and 0.25 or less as a predetermined value P in a storage unit (not shown) according to an instruction from the operator of the solid fuel crusher 100. And

  The predetermined value P of O / C at which the ignitability of the pulverized fuel rapidly increases is determined to be a substantially constant value depending on the type of solid fuel. In this embodiment, coal is used as the solid fuel, and coal types such as bituminous coal (highly volatile A), bituminous coal (highly volatile B), bituminous coal (highly volatile C), subbituminous coal A, subbituminous coal B For example, the sub-bituminous coal C and the like, the O / C is calculated in advance for the type of coal that is actually planned to be used, and the temperature that leads to ignition is measured for each type of coal that possesses each O / C. Organize under a graph like Thereby, in the coal of this embodiment, the predetermined value P of O / C where the ignitability of the pulverized fuel rapidly increases exists in the range of O / C of 0.10 or more and 0.25 or less. The predetermined value P can be acquired based on the test result. For this reason, even if the coal type to be used is changed, O / C is calculated in advance for the coal type by analysis, and it is evaluated whether it is greater than or less than a predetermined value P of each O / C. Thus, the upper limit temperature of the outlet temperature can be determined.

  In step S302, the control unit 50 sets O / C obtained and obtained in advance for the solid fuel transported from the coal feeder 20 by analysis. In addition, when the kind of solid fuel conveyed from the coal feeder 20 is changed, the value of O / C shall be set to O / C of the changed solid fuel.

  In step S303, the control unit 50 determines whether the O / C set in step S302 is smaller than the predetermined value P set in step S301. If YES, the process proceeds to step S304. If NO, The process proceeds to step S309.

  In step S304, since the O / C is smaller than the predetermined value P, the control unit 50 sets the first temperature T1 as the upper limit temperature of the outlet 19 of the mill 10. In the present embodiment, an appropriate temperature is set as a first temperature T1 from a range of 70 to 85 ° C. that does not include 70 ° C. The first temperature T1 is preferably set to a high temperature in order to increase the combustion efficiency of the boiler 200, and is preferably set to a low temperature in order to suppress the risk of ignition inside the housing 11. Also take into account.

In step S <b> 305, the control unit 50 refers to the temperature output from the temperature detection unit 40 and detects the temperature Td at the outlet 19 of the mill 10.
In step S306, the control unit 50 determines whether or not the detected temperature Td is higher than the first temperature T1, and if YES, the process proceeds to step S307, and if NO, the process proceeds to S308.

  In step S307, since the detected temperature Td is higher than the first temperature T1 and there is a high risk that the pulverized fuel will ignite, the control unit 50 performs control so as to lower the temperature of the primary air. Specifically, the control unit 50 reduces the temperature of the primary air supplied to the mill 10 by reducing the opening degree of the hot gas damper 30c or increasing the opening degree of the cold gas damper 30d. The control unit 50 may reduce the opening degree of the hot gas damper 30c and increase the opening degree of the cold gas damper 30d.

  In step S308, the control unit 50 determines whether or not an end instruction for ending the process shown in the flowchart is given. If the end instruction is given, the process shown in the flowchart is ended. The control unit 50 repeats the processes from step S305 to step S307 again when the end instruction is not given.

  As described above, when the first temperature T1 is set as the upper limit temperature of the outlet 19 of the mill 10 in step S304, the control unit 50 does not exceed the first temperature T1 by the temperature detection unit 40. Thus, the air blowing unit 30 is controlled. Specifically, the control unit 50 controls the air flow rate of at least one of the hot gas damper 30c and the cold gas damper 30d so that the temperature Td detected by the temperature detection unit 40 does not exceed the first temperature T1.

  On the other hand, in step S309, the controller 50 sets the second temperature T2 lower than the first temperature T1 as the upper limit temperature of the outlet 19 of the mill 10 because O / C is equal to or greater than the predetermined value P. In the present embodiment, an appropriate temperature is set as the second temperature T2 from the range of 55 to 70 ° C. The second temperature T2 is preferably set to a high temperature in order to increase the combustion efficiency of the boiler 200, and is preferably set to a low temperature in order to suppress the risk of ignition inside the housing 11. Also take into account. Further, it is preferable to confirm that condensation does not occur in the supply channel 100b on the downstream side when the temperature is lower than 55 ° C.

In step S <b> 310, the control unit 50 refers to the temperature output from the temperature detection unit 40 and detects the temperature Td of the outlet 19 of the housing 11 of the mill 10.
In step S311, the control unit 50 determines whether or not the detected temperature Td is higher than the second temperature T2, and if YES, the process proceeds to step S312 and if NO, the process proceeds to S313.

  In step S312, since the detected temperature Td is higher than the second temperature T2 and there is a high risk that the pulverized fuel will ignite, the control unit 50 controls the temperature of the primary air to be lowered. Specifically, the control unit 50 reduces the temperature of the primary air supplied to the mill 10 by reducing the opening degree of the hot gas damper 30c or increasing the opening degree of the cold gas damper 30d. The control unit 50 may reduce the opening degree of the hot gas damper 30c and increase the opening degree of the cold gas damper 30d.

  In step S313, the control unit 50 determines whether or not an end instruction for ending the process shown in the flowchart is given. If the end instruction is given, the control unit 50 ends the process shown in the flowchart. The control unit 50 repeats the processes from step S310 to step S312 again when no termination instruction is given.

  As described above, when the control unit 50 sets the second temperature T2 as the upper limit temperature of the outlet 19 of the mill 10 in step S309, the temperature Td detected by the temperature detection unit 40 does not exceed the second temperature T2. Thus, the air blowing unit 30 is controlled. Specifically, the control unit 50 controls the blowing amount of at least one of the hot gas damper 30c and the cold gas damper 30d so that the temperature Td detected by the temperature detection unit 40 does not exceed the second temperature T2.

The operation and effect of the solid fuel crusher 100 of the present embodiment described above will be described.
According to the solid fuel pulverization apparatus 100 of the present embodiment, when the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel (hereinafter referred to as O / C) is smaller than a predetermined value P, the primary air The first temperature T1 is set as the upper limit temperature, and when the O / C is equal to or higher than the predetermined value P, the second temperature T2 lower than the first temperature T1 is set. Therefore, when pulverizing a solid fuel having an O / C equal to or higher than a predetermined value P and a low ignition temperature, the upper limit temperature is set low, and the pulverized fuel is prevented from igniting. Further, the control unit 50 sets only two types of the upper limit temperature, ie, the first temperature T1 when O / C is smaller than a predetermined value and the second temperature T2 when O / C is equal to or higher than the predetermined value. The ignition of pulverized fuel can be prevented by simple control.

In addition, the solid fuel pulverization apparatus 100 according to the present embodiment mixes another type of solid fuel and mixes the O / C even when pulverizing the solid fuel whose O / C is equal to or higher than the predetermined value P and whose ignition temperature is low. The second temperature lower than the first temperature may be selected as the upper limit temperature of the temperature detection unit 40 to be managed without changing the properties of the solid fuel by adjusting the temperature of the burner unit such as the boiler 200. The pulverized fuel having a certain property can be stably supplied to 220, and a decrease in combustion efficiency of the boiler 200 or the like can be suppressed.
Here, only two types of the first temperature T1 and the second temperature T2 are set as the upper limit temperature because the ignitability of the pulverized fuel when the O / C becomes a predetermined value P or more by the inventors. This is because new knowledge that it rises rapidly is obtained.

  In the solid fuel crusher 100 of the present embodiment, the temperature detection unit 40 detects the temperature of the outlet 19 from which the pulverized fuel is discharged from the housing 11. The outlet 19 from which the pulverized fuel is discharged from the housing 11 is a portion after the solid fuel is pulverized and further classified, and is present at a high concentration of pulverized fuel suitable for the downstream burner 220. Therefore, it is a part directly related to the ignitability of pulverized fuel. Therefore, the temperature of the outlet 19 can be approximated as the internal temperature of the housing 11, and by detecting the temperature of the outlet 19 and controlling the blower 30 so as not to exceed the upper limit temperature, the pulverized fuel inside the housing 11 is controlled. Ignition can be reliably prevented.

In the solid fuel crusher 100 of the present embodiment, the blower unit 30 includes a hot gas damper 30c that blows hot air heated by a heater, and a cold gas damper 30d that blows cold air having a temperature lower than that of the hot air. . Further, the control unit 50 controls the temperature of the primary air blown to the housing 11 by adjusting the blowing amount of at least one of the hot gas damper 30c and the cold gas damper 30d.
In this way, the control unit 50 adjusts at least one of the amount of hot air blown by the hot gas damper 30c and the amount of cold air blown by the cold gas damper 30d, and the temperature of the primary air is set. It can control so that an upper limit temperature may not be exceeded.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described.
The second embodiment is a modification of the first embodiment, and is the same as the first embodiment except for the case described below, and the description below is omitted.

  The solid fuel pulverization apparatus 100 according to the first embodiment uses solid fuel such as coal having a single property, and a plurality of types of solid fuel having different properties are mixed and supplied from the coal feeder 20 to the mill 10. It was not a thing. On the other hand, the solid fuel crusher of this embodiment mixes solid fuels such as a plurality of types of coal having different properties and supplies them to the mill 10 from the coal feeder 20.

  Moreover, the control part 50 of the solid fuel crusher 100 of 1st Embodiment set O / C of the solid fuel of a single property by step S302. On the other hand, the solid fuel crusher of this embodiment sets O / C of multiple types of solid fuels having different properties in step S302.

  In step S302 shown in FIG. 3, the control unit of the solid fuel crusher of the present embodiment sets O / Cs for a plurality of types of solid fuels. Here, since the properties of the plurality of types of solid fuels are different, the O / C values of the plurality of types of solid fuels are also different.

  Then, when determining whether or not the O / C is smaller than the predetermined value P in step S303, the control unit of the present embodiment has the largest O / C among the plurality of O / C values set in step S302. It is determined whether or not the value is smaller than a predetermined value P.

  This is because the O / C value of the solid fuel having the lowest ignition temperature among a plurality of types of solid fuel is used as a reference. In this way, when a mixture of a plurality of types of solid fuels is used, a problem that ignition occurs inside the housing 11 of the mill 10 can be assured as compared to a case where an average value of a plurality of O / Cs is used. Can be suppressed.

DESCRIPTION OF SYMBOLS 10 Mil 11 Housing 12 Rotary table 13 Roller 14 Drive part 15 Drive shaft 16 Classification part 17 Fuel supply part 18 Motor 19 Outlet 20 Coal feeder (fuel supply part)
30 Blower 30a Hot gas blower 30b Cold gas blower 30c Hot gas damper (first blower)
30d Cold gas damper (second air blower)
40 Temperature Detection Unit 50 Control Unit 100 Solid Fuel Crusher 100a Primary Air Channel 100b Supply Channel 200 Boiler 210 Furnace 220 Burner Unit (Combustion Device)

Claims (7)

A solid fuel crusher for crushing solid fuel and supplying it to a combustion device,
A rotary table that is rotated by a driving force from a driving unit;
A roller for pulverizing the solid fuel supplied to the rotary table from a fuel supply unit;
A classifying unit for classifying the solid fuel pulverized by the roller into a pulverized fuel smaller than a predetermined particle size;
A housing for housing the rotary table, the roller, and the classifying unit;
A blower for blowing primary air into the housing for supplying the solid fuel crushed by the roller to the classification unit;
A temperature detector for detecting the temperature of the primary air in the housing;
A preset upper limit temperature for managing the temperature detected by the temperature detection unit, and a control unit for controlling the blower unit so as not to exceed the upper limit temperature,
The control unit sets the first temperature when the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel is smaller than a predetermined value as the upper limit temperature, and when the ratio is equal to or higher than the predetermined value And a solid fuel pulverizer for setting a second temperature lower than the first temperature.   The solid fuel pulverization apparatus according to claim 1, wherein the temperature detection unit detects a temperature at an outlet from the housing from which the fine fuel is discharged from the housing. The blowing section includes a first blowing section that blows hot air heated by a heater, and a second blowing section that blows cold air having a temperature lower than that of the hot air,
The said control part controls the temperature of the said primary air ventilated to the said housing by adjusting the ventilation volume of at least any one of a said 1st ventilation part and a said 2nd ventilation part. The solid fuel pulverization apparatus described.   The solid fuel crusher according to any one of claims 1 to 3, wherein the predetermined value is not less than 0.1 and not more than 0.25.   5. The solid fuel pulverization apparatus according to claim 1, wherein the first temperature is higher than 70 ° C. and 85 ° C. or lower, and the second temperature is 55 ° C. or higher and 70 ° C. or lower. The roller pulverizes a plurality of types of the solid fuel having different properties,
The controller sets the first temperature as the upper limit temperature when the largest ratio among the ratios of the plurality of types of the solid fuels is smaller than the predetermined value, and the plurality of types of the solid fuels. The solid fuel pulverization apparatus according to any one of claims 1 to 5, wherein the second temperature is set when the largest ratio among the ratios is equal to or greater than the predetermined value. A control method for a solid fuel pulverizer that pulverizes solid fuel and supplies it to a combustion device,
The solid fuel pulverizing apparatus includes a rotary table that is rotated by a driving force from a driving unit, a roller that pulverizes the solid fuel supplied from the fuel supply unit to the rotary table, and the solid fuel that is pulverized by the roller. A classification part for classifying into finely pulverized fuel smaller than a predetermined particle size, a housing for accommodating the rotary table, the roller, and the classification part, and a primary for supplying the solid fuel crushed by the roller to the classification part A blower that blows air into the housing;
A temperature detecting step of detecting a temperature of the primary air in the housing;
An upper limit temperature for managing the temperature detected by the temperature detection step is set in advance, and a control step for controlling the blower so as not to exceed the upper limit temperature;
A setting step for setting the upper limit temperature,
The setting step sets the first temperature when the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel is smaller than a predetermined value as the upper limit temperature, and the ratio is equal to or higher than the predetermined value. And a control method for the solid fuel crusher, wherein a second temperature lower than the first temperature is set.

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