JPH1157513A - Revolving speed controller of mill rotary classifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the mill coal output characteristic with good responsiveness from the optimum time even if the conditions such as water content of coal, unoperational time of the mill and outside air temp. are changed when the mill is started. SOLUTION: This revolving speed controller 40 of a mill rotary classifier is provided with a first function generator 33 for outputting a revolving speed command 30 based on a coal supply command 25, a second function generator 34 for outputting a low revolving speed command 31 based on a mill start signal 26 and a switch 35 switching the revolving speed control command 30 and a low revolving speed command 31 and outputting the command to a classifier motor 16 and further furnished with a thermometer 38 for detecting the temp. close to a mill crushing part and a switching indicator 43 for allowing the switch 35 outputting the low revolving speed command 31 to the motor 16 when the mill is started to output the revolving speed command 30 to the motor 16 when the temp. 39 detected by the thermometer 38 is increased to a set temp. 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed control device for a mill rotary classifier.

[0002]

2. Description of the Related Art As a pulverized coal mill for pulverizing coal and supplying pulverized coal to a coal-fired boiler, there is a pulverized coal mill provided with a rotary classifier for classifying and extracting pulverized coal.

FIG. 4 shows an example of a mill provided with a rotary classifier. A table 4 which is horizontally rotated by a driving device 3 is arranged in a lower part of a casing 2 of the mill 1, and is arranged above the table 4. A roller 7 that can be turned up and down by a fluid pressure cylinder 5 via a horizontal shaft 6 is disposed. The roller 7 is pressed by the fluid pressure cylinder 5 against the horizontally rotating table 4. And the table 4 cooperate with each other so that the coal on the table 4 can be crushed. 1a is a mill pulverizing section.

An annular body 8 is arranged in the casing 2 so as to surround the table 4. The annular body 8 has primary air 9 introduced into the casing 2 from a position below the table 4 of the casing 2. An air nozzle 10 is provided so that air can be blown into the upper part of the casing 2.

A hollow frame 11 communicating with the inside of the casing 2 is installed outside the upper part of the casing 2, and a bearing cylinder 12 fixed vertically extending inside the hollow frame 11 has a vertical Bearing 13 at required intervals
And a pulverized coal feed pipe 14 for feeding pulverized coal to a burner (not shown) of the boiler is connected to a side portion of the hollow frame 11.

A vertically extending rotating chute 15 is fitted into the bearing 13, and the upper end of the rotating chute 15 projects above the hollow frame 11.
The lower end of 5 is located slightly above roller 7 in casing 2.

A pulley 17 is fitted around the output shaft of a vertical classifier motor 16 installed outside the upper part of the casing 2.
An endless belt 19 is wound between the pulley 17 and the pulley 18, which is fitted and fixed outside and near the upper end of the rotary chute 15. Further, a rotary classifier 20 provided with a plurality of rotary blades 20a in a circumferential direction is mounted on an outer periphery of a halfway portion of the rotary chute 15 in the vertical direction so as to be located at an upper portion in the casing 2.

A rotary classifier 2 is provided in the casing 2.
0, a hopper 21 having a truncated inverted conical shape is provided.
A slit 21a extending along the inclined surface is provided so that the ascending coal can pass through.

Above the rotary chute 15, a coal feeder 22 for supplying coal to the rotary chute 15 by driving a coal feeder motor 23 is disposed, and a chute 22a of the coal feeder 22 is provided. The lower end is connected to the upper end of the rotary chute 15 via the rotary joint 22b.

In the mill 1 shown in FIG. 4, coal cut out from a coal hopper (not shown) to a coal feeder 22 is
It is thrown into the casing 2 via the rotating chute 15,
The table 4 is dropped on the table 4 and is pulverized by the cooperative work of the table 4 driven by the driving device 3 and rotating in the horizontal direction and the roller 7 pressed against the table 4 and rotating. The coal is entrained by the primary air 9 blown out from the air nozzle 10 and rises in the casing 2 as shown by an arrow, enters the hopper 21 through the slit 21 a of the hopper 21, and is driven by the classifier motor 16 together with the rotary chute 15. The coarse coal is classified by the rotating rotary classifier 20, and the pulverized coal obtained by classifying the coarse particles enters the hollow frame 11 through the rotary classifier 20, and is supplied from the hollow frame 11 to the pulverized coal feed pipe 14. The coarse particles that have been sent to the boiler burner (not shown) and classified by the rotary classifier 20 slide down the hopper 21 and are returned to the table 4.

The primary air 9 supplied to the mill 1 usually has a temperature of about 200 to 240 ° C. to dry the coal, and the temperature at the mill outlet (the temperature of the pulverized coal feed pipe 14 part). ) Is maintained at a set temperature of 70 ° C., for example, so that the temperature of the primary air 9 supplied to the mill 1 is adjusted.

In FIG. 4, reference numeral 24 denotes a mill control device, to which a coal feed command 25 (mill master) and a mill start command 26 are input, and which are provided in the pulverized coal feed pipe 14. Mill outlet temperature 28 detected by thermometer 27
And outputs a coal feeder command 29 to the coal feeder motor 23 and a rotation speed control command 30 or a low rotation speed command 31 to the classifier motor 16. In addition, the mill start command 26 is instructed to a primary air damper (not shown) to start supplying the primary air 9 to the mill 1.

When the load (coal feed amount command 25) is increased, the mill 1 is controlled so that the coal feed amount by the coal feeder 22 is increased, and the flow rate of the primary air 9 is increased. It is controlled so that the flow rate of the pulverized coal discharged from the pulverized coal feed pipe 14 is increased.

However, since the mill 1 takes a long time from coal supply to coal removal and takes a long time, the mill 1 is controlled by controlling the rotation speed of the rotary classifier 20. The characteristics are controlled. In other words, the rotary classifier 20 reduces the resistance and reduces the resistance of the pulverized coal when the rotation speed is reduced, and increases the resistance when the rotation speed is increased and makes the pulverized coal difficult to be derived. In order to control the coal output characteristics with high responsiveness. At this time, when the mill load is high, the rotary classifier 2
0 to reduce the number of revolutions so that pulverized coal is easily delivered, and when the mill load is low, increase the number of revolutions of the rotary classifier to prevent the removal of coarse powder. Thereby, the fineness of the pulverized coal discharged from the pulverized coal feed pipe 14 is kept substantially constant.

On the other hand, when the mill 1 is started, the mill pulverizing section 1
a is not sufficiently heated, so the crushability of coal is poor,
Therefore, even if the number of revolutions of the rotary classifier 20 is controlled, the coal output characteristics of the mill 1 cannot be effectively controlled.
The rotation speed of 0 is set to a small constant low rotation speed.

FIG. 5 shows an example of a rotation speed control device 32 of the conventional rotary classifier 20 provided in the mill control device 24. As shown in FIG. A first function generator 33 for outputting a rotation speed control command 30 by a motor, a second function generator 34 for outputting a low rotation speed command 31 according to a mill start command 26 as shown in FIG. A switching unit 35 is provided for switching between the rotation speed control command 30 from the function generator 33 and the low rotation speed command 31 from the second function generator 34 and outputting to the classifier motor 16.

The switching unit 35 changes the rotation speed control command 30 from the first function generator 33 and the low rotation speed command 31 from the second function generator 34 in a gradual manner. It is provided with an interpolation circuit like a device.

Further, the switch 35 is normally located on the side b, and when the mill start command 26 is generated, the low speed command 31 from the second function generator 34 is transmitted to the classifier motor 1.
6 is output to the switch 35 after a predetermined time H (for example, 60 minutes) elapses after the mill start command 26 is generated. Timer 3 that switches to the side
And a rotation speed control command 3 from the first function generator 33 in response to a switching signal 36 from the timer 37.
0 is output to the classifier motor 16.

When a mill start command 26 is issued to the mill control device 24 shown in FIG. 4, a mill start command 26 is issued to a primary air damper (not shown), and primary air of about 200 to 240 ° C. is supplied to the mill 1. The warming of the mill 1 is thereby started, and the low speed command 31 from the second function generator 34 is transmitted via the switch 35 by the mill start command 26 in the speed control device 32 of FIG. 8 is output to the classifier motor 16 and the rotary classifier 20
(A), the motor is rotated at a constant low speed.

When the inside of the mill 1 is gradually warmed by the supply of the primary air 9, the mill outlet temperature 28 is also changed as shown in FIG.
It will gradually rise like.

When the mill outlet temperature 28 reaches, for example, 50 ° C., a minimum set amount of the coal feeder command 2 shown in FIG.
9 is output to the coal feeder motor 23 of FIG. 4 and the coal feeder motor 23 is driven, so that a minimum set amount of coal is supplied onto the table 4 via the rotary chute 15. At the same time, the rotation of the table 4 is driven by the driving device 3 of FIG. 4, and the comminution of the coal by the comminuting unit 1a is started.

By cooling the inside of the mill 1 by supplying the minimum set amount of coal, the mill outlet temperature 28
8C once falls as shown in FIG. 8C, but then rises again, and the mill outlet temperature 28 is, for example, 50 ° C. + α.
When the temperature reaches (5 ° C.), as shown in FIG. 8B, the coal feeder command 29 is switched from the minimum set amount of coal feeder command 29 to the coal feeder command 29 based on the coal feed amount command 25, and shifts to automatic control. I will be.

By the time the coal feeder 22 is automatically controlled, as shown in FIG.
Since the temperature of 8 reaches the set temperature of 70 ° C., the temperature of the primary air 9 supplied to the mill 1 is adjusted so as to maintain the temperature of 70 ° C. thereafter.

When a predetermined time H, for example, 60 minutes, has elapsed since the generation of the mill start command 26, the timer 37 shown in FIG. The switch 35 is switched so that the rotation speed control command 30 from the function generator 33 is output to the classifier motor 16, and thereafter, the automatic control by the rotation speed control command 30 based on the coal feed amount command 25 is performed. Transition.

The setting of the fixed time H (60 minutes) from the generation of the mill start command 26 to the output of the switching signal 36 of the timer 37 to the switching unit 35 is performed when the coal supplied to the mill 1 is wet. Under such conditions that the water content is very large or the mill 1 has a long stopping time and the outside air temperature is very low, the rise of the mill outlet temperature 28 is slow, and as shown by a broken line 28 ′ in FIG. In consideration of a case where it takes time to increase the outlet temperature, it is set to be longer.

[0026]

However, as described above, in the rotation speed control device 32 of the conventional rotary classifier 20, the timer 37 generates a fixed time H (60 minutes) from the generation of the mill start command 26. If the time has not elapsed, it is not possible to shift to the automatic control based on the rotation speed control command 30 from the first function generator 33. When the mill 1 is restarted, the temperature in the mill 1 has a sufficiently high temperature, and therefore, it is possible to control the mill coal removal characteristics by the rotary classifier 20 in a short time of warming. Nevertheless, conventionally, there is a waste of time of waiting for 60 minutes.
According to the change of the situation such as the stop time of the mill 1 and the outside air temperature
It was not possible to control the mill coal output characteristics from an appropriate time with good responsiveness.

The present invention has been made in view of the above circumstances, and even when the condition such as the water content of coal, the stop time of the mill and the outside air temperature changes at the start of the mill, the mill coal output characteristics are optimized. An object of the present invention is to provide a rotation speed control device of a mill rotary classifier that can be controlled with good responsiveness from the time.

[0028]

SUMMARY OF THE INVENTION The present invention provides a first function generator for outputting a rotation speed control command based on a coal supply command, and a second function for outputting a low rotation speed command according to a mill start command. A mill rotary type comprising: a generator; and a switch for switching between a rotation speed control command from the first function generator and a low rotation speed command from the second function generator and outputting to the classifier motor. A rotational speed control device for a classifier, a thermometer for detecting a metal temperature in the vicinity of a mill pulverizing section;
The switch that outputs the low rotation speed command from the function generator to the classifier motor is classified into a rotation speed control command from the first function generator when the temperature detected by the thermometer rises to the set temperature. And a switching indicator for switching the output to the machine motor.

According to the present invention, when the detected temperature of the mill pulverizing section reaches the set temperature, the rotation speed control command from the first function generator is changed from the low rotation speed command from the second function generator. Switching to automatic control is performed, so even if there are changes in the water content of the coal, changes in the temperature inside the mill due to the mill stop time, changes in the outside air temperature, etc., the low rotation speed command To the rotation speed control command can be performed at the optimum timing without causing time waste as in the past, so that the mill coal output characteristics can be improved from the early stage at the start of the mill with good responsiveness. Can be controlled.

[0030]

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

FIGS. 1 and 2 show an embodiment of the present invention. In FIG. 1 and FIG. 2, parts denoted by the same reference numerals as those in FIGS. 4 and 5 represent the same parts. This is similar to the conventional one shown in FIGS. 4 and 5, but the feature of the illustrated example is that, as shown in FIG. 1, a thermometer 38 for detecting the metal temperature of the mill crushing section 1a is provided. In addition, the detected temperature 39 of the thermometer 38 is input to the mill control device 24. The thermometer 38 includes a mill crushing unit 1a.
In the illustrated example, the metal temperature at a position near the upper side of the air nozzle 10 in the casing 2 is detected.

FIG. 2 shows an example of a rotation speed control device 40 of the rotary classifier 20 provided in the mill control device 24.
Function generator 33 that outputs
Function generator 3 which outputs a low-speed command 31 by means of
4 and a switching unit 35 for switching between a rotation speed control command 30 from the first function generator 33 and a low rotation speed command 31 from the second function generator 34 and outputting to the classifier motor 16. Normally, when the mill start command 26 is issued on the b side and the mill start command 26 is issued, the low speed command 31 from the second function generator 34 is issued.
Switch 3 which outputs the output to the classifier motor 16
5, the detected temperature 39 of the thermometer 38 is the set temperature 4
A switching indicator 43 is provided which outputs a switching signal 42 for switching to the b side so as to output the rotation speed control command 30 from the first function generator 33 to the classifier motor 16 when it rises to 1. I have.

The above-mentioned set temperature 41 is the mill outlet temperature 2
When the set temperature of 8 is 70 ° C., a temperature lower than 70 ° C. and close to 70 ° C., for example, about 50 to 65 ° C. is selected.

Next, the operation of the above embodiment will be described.

When a mill start command 26 is issued to the mill control device 24 shown in FIG. As a result, the warming of the mill 1 is started, and the low speed command 31 from the second function generator 34 is switched to the b side by the mill start command 26 in the speed control device 40 of FIG. Is output to the classifier motor 16 via the switch 35
The rotary classifier 20 is rotated at a constant low rotation speed as shown in FIG.

When the inside of the mill 1 is gradually warmed by the supply of the primary air 9, the mill outlet temperature 28 is also changed as shown in FIG.
So that the mill outlet temperature 28 is, for example, 50 ° C.
Is reached, the coal feeder command 29 of the minimum set amount shown in FIG. 3 (B) is output to the coal feeder motor 23 of FIG. A quantity of coal is fed onto the table 4 via a rotary chute 15. At the same time, the rotation of the table 4 is driven by the driving device 3 in FIG. 1, and comminution of the coal by the mill comminuting section 1a is started.

When the inside of the mill 1 is cooled by supplying the minimum set amount of coal, the mill outlet temperature 28
3D falls once as shown in FIG. 3D, but then rises again, and the mill outlet temperature 28 is, for example, 50 ° C. + α.
(5 ° C), the minimum set amount of coal feeder command 29
Then, the operation is switched to the coal feeder command 29 based on the coal feed command 25, and the automatic control is started.

On the other hand, the supply of the primary air 9 gradually increases the metal temperature of the mill pulverizing section 1a, so that the detected temperature 39 of the thermometer 38 also gradually increases as shown in FIG. However, this detected temperature 39 is equal to the set temperature 4
When the temperature reaches 1, for example, 60 ° C., the switching indicator 43 of FIG. 2 outputs the switching signal 42 to the switching unit 35 and outputs the rotation speed control command 30 from the first function generator 33 to the classifier motor 16. The switch 35 is switched as described above.

The fact that the detected temperature 39 for detecting the metal temperature of the casing 2 near the mill crushing section 1a reaches the set temperature 41 close to the mill outlet temperature (70 ° C.)
Mill 1 has been preheated enough,
Therefore, thereafter, as shown in FIG.
5, the automatic control is performed by the rotation speed control command 30 based on the control value 5, and good coal output characteristics can be obtained.

Therefore, when it takes time to increase the temperature at the mill outlet as shown by the broken line 28 'in FIG. 3D, the detection of the mill pulverizing section 1a as shown by the broken line in FIG. Since it takes time to increase the temperature 39, when the detected temperature 39 reaches the set temperature 41, by switching from the low speed command 31 to the automatic control by the speed control command 30 based on the coal feed command 25, Thus, it is possible to always shift to the automatic control at a good timing.

As described above, based on the detected temperature 39 of the mill crushing section 1a, the switching to the automatic control by the rotation speed control command 30 from the first function generator 33 is performed. Changes in the water content, changes in the temperature inside the mill 1 due to the stop time of the mill 1, changes in the outside air temperature, etc., these changes are all changes in the temperature rise of the mill crushing section 1a. By shifting to the automatic control based on the rotation speed control command 30 based on the set temperature 41 based on the detected temperature 39 of the mill crushing unit 1a, time waste as in the related art is generated. In addition, the switching from the low rotation speed command 31 to the rotation speed control command 30 of the rotary classifier 20 can be performed at an optimum timing. It is possible to control.

It should be noted that the rotation speed control device of the mill rotary classifier of the present invention is not limited to the above-described illustrated example, and that various changes can be made without departing from the gist of the present invention. Of course.

[0043]

As described above, according to the present invention,
When the detected temperature of the mill crushing section reaches the set temperature, switching is performed to shift from the low rotation speed command from the second function generator to the automatic control based on the rotation speed control command from the first function generator. Therefore, even if there is a change in the water content of coal, a change in the temperature inside the mill due to the stop time of the mill, a change in the outside air temperature, etc., the switching from the low rotation speed command to the rotation speed control command is performed. , At the right time, without wasting time like in the past,
Therefore, an excellent effect that the mill coal removal characteristics can be controlled with good responsiveness from an early stage at the start of the mill can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an example of an embodiment of the present invention.

FIG. 2 is a block diagram of a rotation speed control device according to an example of an embodiment of the present invention.

FIG. 3 is a diagram illustrating the operation of the embodiment of the present invention, (A) classifier rotation speed, (B) coal feeder command,
It is the diagram which showed the relationship between the detection temperature of the mill crushing part of (C), and the mill exit temperature of (D).

FIG. 4 is a schematic vertical sectional view showing an example of a conventional mill.

FIG. 5 is a block diagram illustrating an example of a conventional rotation speed control device.

FIG. 6 is a diagram showing the operation of the first function generator.

FIG. 7 is a diagram showing the operation of the second function generator.

FIG. 8 is a diagram showing a relationship among a classifier rotation speed of (A), a coal feeder command of (B), and a mill outlet temperature of (C) for explaining the operation of the conventional apparatus. .

[Explanation of symbols]

 25 Coal feed command 26 Mill start command 30 Revolution control command 31 Low revolution command 33 First function generator 34 Second function generator 35 Switch 38 Thermometer 39 Detected temperature 40 Revolution control device 41 Set temperature 43 Switching indicator

Claims (1)

[Claims] A first function generator for outputting a rotation speed control command based on a coal supply command; a second function generator for outputting a low rotation speed command in response to a mill start command; A rotation speed control device for a mill rotary classifier having a switch for switching between a rotation speed control command from a function generator and a low rotation speed command from a second function generator and outputting the same to a classifier motor. A thermometer for detecting a metal temperature in the vicinity of the mill pulverizing section; and a switch for outputting a low-speed command from the second function generator to the classifier motor at the time of starting the mill. A switching indicator for switching so as to output a rotation speed control command from the first function generator to the classifier motor when the detected temperature rises to the set temperature, and a rotation speed of the mill rotary classifier. Control device.