JP7086535B2 - Control method of solid fuel crusher and solid fuel crusher - Google Patents

Description

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

Conventionally, there is known a crusher that crushes a solid fuel such as coal into fine particles smaller than a predetermined particle size and supplies the fuel to a combustion device such as a boiler (see, for example, Patent Document 1).
According to Patent Document 1, when the concentration of carbon monoxide and / or carbon dioxide is measured at the outlet of the crusher, it is determined that the oxidation reaction of the fuel, which is a sign of ignition, is occurring, and the ignition temperature is low. It is disclosed that the ignition temperature of a solid fuel in which a plurality of types are mixed is raised by reducing the supply amount of carbon dioxide to prevent ignition in the crusher.

Japanese Unexamined Patent Publication No. 2011-240250

However, in Patent Document 1, the concentration of carbon monoxide and / or carbon dioxide is measured at the outlet of the crusher in order to determine the sign of ignition. Therefore, a sensor for measuring the concentration of carbon monoxide and / or carbon dioxide is required. Further, in Patent Document 1, pulverized coal supplied from a crusher to a boiler or the like in order to dynamically change the supply amount of coal having a low ignition temperature according to the measured value of the concentration of carbon monoxide and / or carbon dioxide. The properties of are changed. Therefore, the 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 fluctuates or decreases.

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 crusher while suppressing the decrease in the combustion efficiency of the boiler or the like to which the pulverized fuel is supplied. It is an object of the present invention to provide a solid fuel crusher which 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 crusher of the present invention crushes solid fuel and supplies it to a combustion device, and crushes a rotary table that rotates by a driving force from a drive unit and the solid fuel supplied from the fuel supply unit to the rotary table. A roller for classifying the solid fuel crushed by the roller into fine powder fuel having a particle size smaller than a predetermined particle size, a housing for accommodating the rotary table, the roller and the classifying portion, and the roller being crushed. The air blower unit that blows the primary air for supplying the solid fuel to the classification unit into the housing, the temperature detection unit that detects the temperature of the primary air in the housing, and the air blower unit . A control unit for controlling the flow rate and temperature of the primary air to be blown is provided, and the control unit has a predetermined value as a ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid fuel as the upper limit temperature of the primary air. When it is smaller than, the first temperature is set, when the ratio is equal to or higher than the predetermined value, the second temperature lower than the first temperature is set , and the temperature detected by the temperature detection unit is higher than the upper limit temperature. If the fuel is too high, the blower is controlled so that the temperature of the primary air drops .

According to the solid fuel crusher 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, it is set as the upper limit temperature of the primary air. The first temperature is set, and when the O / C is equal to or higher than a predetermined value, the second temperature lower than the first temperature is set. Therefore, when pulverizing a solid fuel having an O / C larger than a predetermined value and a low ignition temperature, the upper limit temperature is set low and the ignition of the fine powder fuel is suppressed. Further, since the control unit sets only two types of upper limit temperatures, the first temperature when the O / C is smaller than the predetermined value and the second temperature when the O / C is larger than the predetermined value, simple control is performed. It is possible to prevent ignition of fine fuel.

Further, the solid fuel crusher of the present invention is a temperature detection unit that manages the solid fuel without changing the properties of the solid fuel even when the O / C is larger than a predetermined value and the ignition temperature is low. Since it is sufficient to select a second temperature lower than the first temperature, it is possible to stably supply fine powder fuel having certain properties to a combustion device such as a boiler and suppress a decrease in combustion efficiency of the boiler or the like. can.

Here, only two types, the first temperature and the second temperature, are set as the upper limit temperature. This is because the inventors have obtained a new finding that when the O / C of the solid fuel becomes a predetermined value or more, the temperature of the fine powder fuel tends to rise due to natural oxidation, and the ignitability rises sharply. Since the fine powder fuel contains water by adsorbing water on the surface, in order for the fine powder fuel to ignite, the amount of latent heat for evaporating the water and the sensible heat for raising the fine powder fuel to the ignition temperature The amount of heat required. Then, it was decided to evaluate the ignitability with respect to a predetermined amount of heat input to the fine powder fuel when there is heating from the surroundings.

When the O / C is smaller than the predetermined value, even if a part of the fine powder fuel reaches the ignition temperature due to the natural oxidation temperature rise, the amount of latent heat for evaporating water reaches the ignition of the fine powder fuel. It is more than the amount of heat. Therefore, it is presumed that the water content of the surrounding fine powder fuel is not sufficiently evaporated and the surrounding fine powder fuel does not reach the ignition temperature. On the other hand, when the O / C is equal to or higher than a predetermined value, when a part of the fine powder fuel reaches the ignition temperature due to the natural oxidation temperature rise, the amount of heat until the fine powder fuel ignites is compared with the calorific value of the latent heat. There are many. Therefore, it is presumed that the water content of the surrounding fine powder fuel can be sufficiently evaporated and the surrounding fine powder fuel can be raised to the ignition temperature. That is, two types of upper limit temperatures can be set depending on whether or not the ignition temperature is reached in the heated state in which the latent heat of the water content of the fine powder fuel is subtracted from the O / C of the solid fuel.

In the solid fuel crushing apparatus of the present invention, the temperature detecting unit may be configured to detect the temperature of the outlet from which the pulverized fuel is discharged from the housing. The outlet from which the pulverized fuel is discharged is the portion after the solid fuel is crushed and further classified, and is the portion directly related to the ignitability of the pulverized fuel. Therefore, even among the temperatures inside the housing, it is more appropriate to control the blower so that the upper limit temperature is not exceeded by detecting the temperature at the outlet, which ensures that the ignition of fine fuel inside the housing is prevented. can do.

In the solid fuel crusher 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 findings 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 is further increased with respect to the predetermined value of the O / C of the solid fuel. It can be reliably prevented. Therefore, it is possible to prevent the ignition of the pulverized fuel inside the housing by simple control while suppressing the decrease in the combustion efficiency of the boiler or the like.

In the solid fuel crusher of the present invention, the blower unit includes a first blower unit that blows hot air heated by a heater and a second blower unit that blows cold air having a temperature lower than that of the hot air. The control unit may control the temperature of the primary air blown to the housing by adjusting the amount of air blown by at least one of the first air blower unit and the second air blower unit. ..
By doing so, the control unit adjusts at least one of the amount of hot air blown by the first blower and the amount of cold air blown by the second blower, and the temperature of the primary air is the upper limit. It can be controlled so as not to exceed the temperature.

In the solid fuel crusher of the present invention, the predetermined values are 0.1 or more and 0.25 or less . The findings obtained by the inventors are that the ignitability of the pulverized fuel sharply increases when the O / C becomes larger than any predetermined value of 0.1 or more and 0.25 or less. Therefore, by setting 0.1 or more and 0.25 or less as predetermined values, ignition of the fine powder fuel inside the housing can be prevented by simple control.

In the control method of the solid fuel crusher of the present invention, the solid fuel crusher that crushes the solid fuel and supplies it to the combustion device has a rotary table in which the solid fuel crusher is rotated by the driving force from the drive unit, and the rotary table from the fuel supply unit to the rotary table. It houses a roller for crushing the supplied solid fuel, a classification unit for classifying the solid fuel crushed by the roller into fine powder fuel having a predetermined particle size, and the rotary table, the roller, and the classification unit. A housing and a blower unit for blowing primary air for supplying the solid fuel crushed by the roller to the classification unit into the housing are provided, and the temperature of the primary air in the housing is detected. A temperature detection step, a control step of controlling the flow rate and temperature of the primary air blown by the blower unit, and a setting step of setting an upper limit temperature of the primary air are provided, and the setting step 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 the predetermined value, and is lower than the first temperature when the ratio is equal to or higher than the predetermined value. A second temperature is set, and in the control step, when the temperature detected by the temperature detection step is higher than the upper limit temperature, the blower unit is controlled so that the temperature of the primary air is lowered, and the predetermined value is set. The first temperature is higher than 70 ° C. and lower than 85 ° C., and the second temperature is 55 ° C. or higher and 70 ° C. or lower .

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

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

It is a block diagram which shows the solid fuel crushing apparatus and boiler of one Embodiment of this invention. It is a figure which shows the upper limit temperature of a mill outlet with respect to O / C. It is a flowchart which shows the process which a control part executes.

Hereinafter, an embodiment of the solid fuel crushing apparatus and the control method thereof according to the present invention will be described with reference to the drawings.
[First Embodiment]
Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.
The solid fuel crushing device 100 of the present embodiment is a device that crushes solid fuel such as coal to generate fine pulverized fuel and supplies it to the burner portion (combustion device) 220 of the boiler 200.
The solid fuel crusher 100 of the present 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" means the direction of the vertically upper side, and "upper" such as the upper part and the upper surface means the part on the vertical upper side.

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 houses the rotary table 12, the rollers 13, the classification unit 16, and the fuel supply unit 17.

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

The roller 13 is a rotating body that crushes the solid fuel supplied from the fuel supply unit 17 to the rotary table 12. The roller 13 is pressed against the upper surface of the rotary table 12 and cooperates with the rotary table 12 to crush the solid fuel. Although only one roller 13 is shown in FIG. 1, a plurality of rollers 13 are arranged at regular intervals in the circumferential direction so as to press the upper surface of the rotary table 12. For example, three rollers 13 are arranged on the outer peripheral portion at an angular interval of 120 °. In this case, the portion where the three rollers 13 are in contact with the upper surface of the rotary table 12 (the portion to be pressed) is equidistant from the center of the rotary table 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.
In the classification unit 16, the solid fuel crushed by the roller 13 is larger than a predetermined particle size (for example, 70 to 100 μm) (hereinafter, the crushed solid fuel exceeding the predetermined particle size is referred to as “coarse powder fuel”). It is a device for classifying crushed solid fuel having a predetermined particle size or less (hereinafter, crushed solid fuel having a predetermined particle size or less is referred to as "fine powder fuel"). The classification portion 16 has, for example, a conical trapezoidal outer shape, is attached to the upper part of the housing 11 along the cylindrical axis of the substantially cylindrical housing 11, and is provided with a plurality of classification blades on the outer peripheral side. The classification unit 16 is given a driving force by the motor 18 and rotates about the cylindrical axis of the housing 11.

The crushed solid fuel that has reached the classification unit 16 guides the coarse powder fuel to the rotary table 12 by the relative balance between the centrifugal force generated by the rotation of the classification blade and the centripetal force due to the airflow 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 flow path 100b. The pulverized fuel that has flowed out to the supply flow path 100b is supplied to the burner portion 220 of the boiler 200.

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

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

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

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

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

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

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

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

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

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

Next, a method of preventing ignition of the pulverized fuel inside the housing 11 by simple control will be described.
As described above, the mill 10 grinds the solid fuel inside the housing 11 and dries the fine fuel with the primary air. The solid fuel such as coal crushed by the mill 10 contains water. Therefore, the water contained in the pulverized fuel evaporates by being heated by the primary air heated to a predetermined temperature. When the water contained in the pulverized fuel evaporates to some extent, volatile components such as flammable gas are likely to be released from the pulverized fuel. Therefore, it is important to appropriately control the temperature inside the housing 11 in order to prevent the pulverized fuel from igniting inside the housing 11.

Further, it is known that the ignition temperature of a solid fuel 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 / Cs, and found that the ignitability of the pulverized fuel rapidly increased when the O / C became larger than a predetermined value. I got the knowledge. Based on this new knowledge, it is judged that it is appropriate to set the upper limit temperature to the ignition temperature by dividing it into two types when the O / C of the solid fuel is smaller than or higher than the predetermined value. Came to get.

Here, the coals used in the tests by the inventors are bituminous coal (highly volatile A), bituminous coal (highly volatile B), and bituminous coal (highly volatile B) classified by D388 formulated by ASTM (American Society for Testing and Materials). Highly volatile C), sub-bituminous coal A, sub-bituminous coal B, sub-bituminous coal C, and the like. The O / C value 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 water, and is obtained by separate analysis for each coal type. Therefore, the oxygen atom number in the O / C does not include the oxygen atom number of the water contained or adsorbed in the solid fuel crushed by the mill 10.

According to the tests conducted by the inventors, when the above coal is used as the solid fuel, the ignitability of the pulverized fuel rapidly increases in the range of O / C of 0.10 or more and 0.25 or less. It was found that a predetermined value P of O / C exists. Here, the case where the ignitability is high means the case where the ignition temperature at which the pulverized fuel ignites is low. The inventors measured the temperature at which the pulverized fuel reaches ignition (the temperature corresponding to the outlet 19) by raising 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 ignite in the temperature range where the temperature corresponding to the outlet 19 exceeds 70 to 85 ° C. On the other hand, when the O / C is equal to or higher than the predetermined value P, it has been found that the pulverized fuel may ignite in the 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 inside 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 pulverized fuel suitable for the burner portion 220 of the wake is high, and the ignitability of the pulverized fuel is directly increased. This is because it is a relevant part. On the other hand, among the temperatures inside the housing 11, the temperature at the inlet, which is the space above the rotary table 12, is the high temperature of the primary air flowing in from the primary air flow path 100a, and the primary air flows out to the space above the rotary table 12 inside the housing 11. Then, the heat is taken away by the drying of the solid fuel and the pulverized fuel, and the temperature drops quickly after that. Therefore, the temperature inside the housing 11 is represented by the temperature at the inlet, and the ignitability of the pulverized fuel is judged. 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, it is presumed that the reason why there is a predetermined value P of O / C in which the ignitability of the pulverized fuel rapidly increases is as follows. Since the fine powder fuel contains water by adsorbing water on the surface, in order for the fine powder fuel to ignite, the amount of latent heat that evaporates the water and the amount of sensible heat that raises the fine powder fuel to the ignition temperature And are required. Then, when the pulverized fuel is heated from the surroundings, it is decided to evaluate the ignitability with respect to a predetermined amount of heat input to the pulverized fuel.

When the O / C is smaller than the predetermined value P, even if a part of the fine powder fuel reaches the ignition temperature due to the natural oxidation temperature rise, the calorific value of the latent heat for evaporating water is the calorific value due to the ignition of the fine powder fuel. Many compared to. Therefore, it is presumed that the water content of the surrounding fine powder fuel is not sufficiently evaporated and the surrounding fine powder fuel does not reach the ignition temperature. On the other hand, when the O / C is equal to or higher than the predetermined value P, when a part of the fine powder fuel reaches the ignition temperature due to the natural oxidation temperature rise, the amount of heat until the fine powder fuel ignites is compared with the calorific value of the latent heat. There are many. Therefore, it is presumed that the water content of the surrounding fine powder fuel is sufficiently evaporated and the surrounding fine powder fuel is raised to the ignition temperature. That is, the O / C of the solid fuel 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 the water content of the pulverized fuel is subtracted from the predetermined amount of heat input to the pulverized fuel. It can be judged that it is good to set. At this time, the O / C corresponding to whether or not the ignition temperature is reached becomes the predetermined value P.

In the solid fuel crushing apparatus 100 of the present embodiment, in consideration of the above findings obtained by the inventors, the outlet 19 of the housing 11 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 the present embodiment, as shown in FIG. 2, the upper limit temperature (first temperature) T1 when the O / C is smaller than the predetermined value P is set to a temperature set from 70 to 85 ° C. not including 70 ° C. By setting the upper limit temperature (second temperature) T2 when the O / C is equal to or higher than a predetermined value to a temperature set from 55 to 70 ° C., ignition of the fine powder fuel inside the housing 11 is prevented by simple control. Is.

In the present embodiment, the O / C value of the solid fuel used as the fuel in the solid fuel crusher 100 is separately analyzed by analyzing the gas component heated and burned in advance by using an element concentration analyzer or the like. It shall be calculated in advance. Further, in the present embodiment, the value of each O / C and the pulverized fuel obtained by crushing each solid fuel ignite for a plurality of types of solid fuel (for example, coal type of coal) used in the solid fuel crushing device 100. By obtaining the test results of the temperature to reach (the temperature corresponding to the outlet 19) and arranging the test results 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 executed by the solid fuel crusher 100 of the present embodiment will be described with reference to the flowchart shown in FIG. FIG. 3 is a flowchart showing a process executed by the control unit 50. The control unit 50 executes each process shown in FIG. 3 by executing a program stored in the storage unit (not shown).

In step S301 of FIG. 3, the control unit 50 reads a predetermined value P obtained in advance by a test from a storage unit (not shown) and sets it. As described above, according to the test conducted by the inventors, a predetermined value P of O / C in which the ignitability of the pulverized fuel sharply increases in the range of O / C of 0.10 or more and 0.25 or less. Turned out to exist. Therefore, the control unit 50 stores in the storage unit (not shown) a value in the range of 0.10 or more and 0.25 or less as the predetermined value P according to the instruction by the operator of the solid fuel crushing device 100. And.

The predetermined value P of O / C in which the ignitability of the fine 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 a solid fuel, and coal coal types such as bituminous coal (highly volatile A), bituminous coal (highly volatile B), bituminous coal (highly volatile C), subbituminous coal A, and subbituminous coal B are used. , Subbituminous coal C, etc., O / C is calculated in advance for the coal type to be actually used, and the temperature leading to ignition is measured for each coal type possessing O / C, and Fig. 2 Organize under a graph like. As a result, in the coal of the present embodiment, the predetermined value P of O / C in which the ignitability of the pulverized fuel rapidly increases exists in the range of 0.10 or more and 0.25 or less. , A predetermined value P can be obtained based on the test result. Therefore, even if the coal type to be used is changed, the O / C of the coal type is calculated in advance by analysis, and it is evaluated whether the value is greater than or equal to or smaller than the predetermined value P of each O / C. Therefore, the upper limit temperature of the outlet temperature can be determined.

In step S302, the control unit 50 sets the O / C obtained by analysis in advance for the solid fuel conveyed from the coal feeder 20. When the type of solid fuel conveyed from the coal feeder 20 is changed, the O / C value shall be set to the changed O / C of the 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, and if NO, the process proceeds to step S304. The process proceeds to step S309.

In step S304, the control unit 50 sets the first temperature T1 as the upper limit temperature of the outlet 19 of the mill 10 because the O / C is smaller than the predetermined value P. In the present embodiment, an appropriate temperature is set from the range of 70 to 85 ° C., which does not include 70 ° C., as the first temperature T1. 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 consideration when setting.

In step S305, 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, the control unit 50 controls so as to lower the temperature of the primary air because the detected temperature Td is higher than the first temperature T1 and there is a high risk of ignition of the pulverized fuel. Specifically, the control unit 50 lowers 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 terminating the process shown in this flowchart has been given, and if the end instruction has been given, ends the process shown in this flowchart. If the end instruction is not given, the control unit 50 repeats the processes from step S305 to step S307 again.

As described above, when the control unit 50 sets the first temperature T1 as the upper limit temperature of the outlet 19 of the mill 10 in step S304, the temperature Td detected by the temperature detection unit 40 does not exceed the first temperature T1. The blower unit 30 is controlled in such a manner. Specifically, the control unit 50 controls 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 control unit 50 sets the second temperature T2, which is lower than the first temperature T1, as the upper limit temperature of the outlet 19 of the mill 10 because the O / C is equal to or higher than the predetermined value P. In the present embodiment, an appropriate temperature is set from the range of 55 to 70 ° C. as the second temperature T2. 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 consideration when setting. Further, it is preferable to confirm that when the temperature is lower than 55 ° C., dew condensation does not occur in the supply flow path 100b on the wake side.

In step S310, 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 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, the control unit 50 controls so as to lower the temperature of the primary air because the detected temperature Td is higher than the second temperature T2 and there is a high risk of ignition of the pulverized fuel. Specifically, the control unit 50 lowers 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 terminating the process shown in this flowchart has been given, and if the end instruction has been given, ends the process shown in this flowchart. If the end instruction is not given, the control unit 50 repeats the processes from step S310 to step S312 again.

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. The blower unit 30 is controlled in such a manner. Specifically, the control unit 50 controls 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 crusher 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 the 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 solid fuel having an O / C of a predetermined value P or more and a low ignition temperature is crushed, the upper limit temperature is set low and the ignition of the fine fuel is suppressed. Further, the control unit 50 sets only two types of upper limit temperatures, a first temperature T1 when the O / C is smaller than the predetermined value and a second temperature T2 when the O / C is equal to or higher than the predetermined value. , Ignition of fine fuel can be prevented by simple control.

Further, in the solid fuel crushing device 100 of the present embodiment, even when crushing a solid fuel having an O / C of a predetermined value P or more and a low ignition temperature, another type of solid fuel is mixed and the O / C is mixed. It is sufficient to select a second temperature lower than the first temperature as the upper limit temperature of the temperature of the temperature detection unit 40 to be controlled without changing the properties of the solid fuel by adjusting the fuel, etc. It is possible to stably supply the pulverized fuel having a certain property to the 220 and suppress the decrease in the combustion efficiency of the boiler 200 and the like.
Here, the reason why only two types of the first temperature T1 and the second temperature T2 are set as the upper limit temperature is that the inventors have set the ignitability of the pulverized fuel when the O / C becomes a predetermined value P or more. This is because we have gained new knowledge that the temperature will rise sharply.

In the solid fuel crushing apparatus 100 of the present embodiment, the temperature detecting 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 fine powder fuel is discharged from the housing 11 is a portion after the solid fuel is crushed and further classified, and the concentration of the fine powder fuel suitable for the burner portion 220 of the wake is high. Therefore, it is a part directly related to the flammability of fine 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 portion 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 crushing apparatus 100 of the present embodiment, the blower unit 30 has a hot gas damper 30c for blowing hot air heated by a heater and a cold gas damper 30d for blowing cold air having a temperature lower than that of hot air. .. Further, the control unit 50 controls the temperature of the primary air blown to the housing 11 by adjusting the air flow amount of at least one of the hot gas damper 30c and the cold gas damper 30d.
By doing so, 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 be controlled so as not to exceed the upper limit temperature.

[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 cases described below, and the description thereof will be omitted below.

The solid fuel crusher 100 of the first embodiment uses a 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 wasn't a thing. On the other hand, the solid fuel crusher of the present embodiment mixes solid fuels such as a plurality of types of coal having different properties and supplies them from the coal feeder 20 to the mill 10.

Further, the control unit 50 of the solid fuel crushing device 100 of the first embodiment sets the O / C of the solid fuel having a single property in step S302. On the other hand, in the solid fuel crushing apparatus of the present embodiment, the O / C of a plurality of types of solid fuel having different properties is set in step S302.

The control unit of the solid fuel crusher of the present embodiment sets the O / C of a plurality of types of solid fuel in step S302 shown in FIG. 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 the control unit of the present embodiment determines in step S303 whether the O / C is smaller than the predetermined value P, the control unit 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 the predetermined value P by using the value of.

This is done because the O / C value of the solid fuel having the lowest ignition temperature among the plurality of types of solid fuel is used as a reference. By doing so, when using a mixture of a plurality of types of solid fuels, there is a certain problem that ignition occurs inside the housing 11 of the mill 10 as compared with the case where the average value of a plurality of O / Cs is used. Can be suppressed.

10 Mill 11 Housing 12 Rotating table 13 Roller 14 Drive unit 15 Drive shaft 16 Classification unit 17 Fuel supply unit 18 Motor 19 Outlet 20 Coal dispenser (fuel supply unit)
30 Blower 30a Hot gas blower 30b Cold gas blower 30c Hot gas damper (1st blower)
30d cold gas damper (second blower)
40 Temperature detection unit 50 Control unit 100 Solid fuel crusher 100a Primary air flow path 100b Supply flow path 200 Boiler 210 Fireplace 220 Burner part (combustion device)

Claims (5)

A solid fuel crusher that crushes solid fuel and supplies it to the combustion device.
A rotary table that rotates by the driving force from the driving unit,
A roller that crushes the solid fuel supplied from the fuel supply unit to the rotary table, and
A classification unit that classifies the solid fuel crushed by the roller into fine powder fuel having a diameter smaller than a predetermined particle size.
A housing for accommodating the rotary table, the roller, and the classification unit,
A blower portion that blows primary air for supplying the solid fuel crushed by the roller to the classification portion into the inside of the housing, and a blower portion.
A temperature detection unit that detects the temperature of the primary air in the housing, and
A control unit for controlling the flow rate and temperature of the primary air blown by the blower unit is provided.
The control unit sets the first temperature as the upper limit temperature of the primary air 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 equal to or higher than the predetermined value. If the temperature is higher than the upper limit temperature, the temperature detected by the temperature detecting unit is controlled to lower the temperature of the primary air. death,
The predetermined values are 0.1 or more and 0.25 or less .
A solid fuel crusher having a first temperature higher than 70 ° C and a temperature of 85 ° C or lower and a second temperature of 55 ° C or higher and 70 ° C or lower . The solid fuel crushing device according to claim 1, wherein the temperature detecting unit detects the temperature at the outlet from the housing where the fine fuel is discharged from the housing. The ventilation unit includes a first ventilation unit that blows hot air heated by a heater and a second ventilation unit that blows cold air having a temperature lower than that of the hot air.
2. The solid fuel crusher described. The roller crushes a plurality of types of the solid fuel having different properties.
The control unit 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 crushing apparatus according to any one of claims 1 to 3, wherein the second temperature is set when the largest ratio among the ratios is equal to or higher than the predetermined value. It is a control method of the solid fuel crusher that crushes the solid fuel and supplies it to the combustion device.
The solid fuel crusher has a rotary table that is rotated by a driving force from a drive unit, a roller that crushes the solid fuel supplied from the fuel supply unit to the rotary table, and the solid fuel crushed by the roller. A classification unit for classifying into fine powder fuel smaller than a predetermined particle size, a housing for accommodating the rotary table, the roller, and the classification unit, and a primary for supplying the solid fuel crushed by the roller to the classification unit. A blower portion that blows air into the inside of the housing is provided.
A temperature detection step of detecting the temperature of the primary air in the housing, and
A control step for controlling the flow rate and temperature of the primary air blown by the blower unit, and
The setting process for setting the upper limit temperature of the primary air is provided.
In the setting step, as the upper limit temperature, a 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 when the ratio is equal to or higher than the predetermined value. Is set to a second temperature lower than the first temperature.
In the control step, when the temperature detected by the temperature detection step is higher than the upper limit temperature, the blower unit is controlled so that the temperature of the primary air is lowered.
The predetermined values are 0.1 or more and 0.25 or less .
A method for controlling a solid fuel crusher in which the first temperature is higher than 70 ° C and is 85 ° C or lower, and the second temperature is 55 ° C or higher and 70 ° C or lower .

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