JPH1110025A - Method for controlling mill coal delivery rate and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to stably control a mill coal delivery rate even if the kinds of coal changes by detecting the lift quantity of a mill roller and correcting the number of revolutions of a rotary type classifying machine 14 by the detected value of the lift quantity. SOLUTION: A mill roller 7 is pressed to a pulverizing table 6 under prescribed pressurizing force by a pressurizing device 7a to pulverize coal 3 in this mill cool delivery rate control method. Fine powder 8a is classified by the rotary type classifying machine 14 and is taken out. The coal delivery rate is controlled by a coal delivery rate control command 24 based on a coal delivery rate command 22. The number of revolutions of the rotary type classifying machine 14 is controlled by a command 32 for the number of revolutions of the classifying machine in accordance with the coal delivery rate control command 24. In such a case, the lift quantity of the mill roller 7 is detected and the decrease in the hardness of the coal 3 is detected by a decrease in the detected value 36 of the lift quantity. The number of revolutions of the rotary type classifying machine 14 is then increased. The increase in the hardness of the coal 3 is detected by an increase in the detected value 3 of the lift quantity. The number of revolutions of the rotary type classifying machine 14 is then decreased. The coal delivery rate is thus controlled to the target coal delivery rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a mill coal output.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a roller mill equipped with a rotary classifier conventionally used to pulverize coal supplied to a coal-fired boiler.
The coal 3 is fed from a coal chute 2 into the inside, and a hydraulic cylinder or the like is provided on a grinding groove 6 a formed on an upper surface of a grinding table 6 which is rotationally driven by a motor 4 via a speed reducer 5. A mill roller 7 is provided so that a roller support bracket 7c is rotated about a pin 7b by a pressurizing device 7a and pressed by a predetermined constant pressing force. The coal 3 is pulverized with a mill roller 7 that rolls following the rotation.

[0003] The pulverized particles 8 are floated by primary air 10 blown up from a blowing port 9 provided annularly so as to surround the pulverizing table 6, and have a funnel-like shape which vertically partitions the inside of the casing 1. Slit cone 1
1 is transported upward through an opening 13 formed by raising the outer edge 12 at a plurality of locations in the circumferential direction.
It is guided and classified by the rotary classifier 14 provided in the upper inside,
Only fine powder 8a having a predetermined particle size or less is supplied to a burner or the like of a boiler (not shown) via a fine powder delivery pipe 15 connected to the top of the casing 1.

The coarse powder 8b repelled by the rotating blades 16 of the rotary classifier 14 slides down the inclined surface between the openings 13 of the slit cone 11 and drops from the dropping port 17 at the lower end of the slit cone 11 into the crushing table 6. It is returned to the center and crushed again. 18 is a rotary classifier 14
1 shows an electric motor for rotationally driving a motor.

[0005] One end of a weighing conveyor 20 driven by a motor 19 is located above the coal input chute 2, and a coal bunker 21 is provided above the other end of the weighing conveyor 20. The motor 19 is driven by a coal supply command 22 to control the coal supply by the weighing conveyor 20.

The coal feed amount command 22 is input to a coal feed amount controller 23. The coal feed amount controller 23, as shown in FIG. The control unit 24 outputs a coal supply control command 24 based on the control signal 22.

[0007] Coal feed control command 2 from coal output controller 23
4 is input to a primary air adjustment damper 28 provided in a primary air pipe 27 via a subtractor 25 and a PI adjuster 26, and the flow rate is detected by a flow meter 29 which detects the flow rate of the primary air 10. A signal 30 is input to the subtractor 25 and is subtracted from the coal feed control command 24. The PI controller 26 controls the primary air conditioning damper 28 so that the deviation is eliminated.
Is adjusted to control the flow rate of the primary air 10.

Further, a coal feed control command 24 from the coal output controller 23 is input to a rotation speed controller 31. The rotation speed controller 31 is shown in FIG. A classifier rotation speed command 32 for controlling the rotation speed of the rotary classifier 14 in response to the coal feed control command 24 is output to the electric motor 18 so as to control the rotation speed of the rotary classifier 14. I have.

[0009] As shown in FIG.
Supplied to the upper surface of the pulverizing table 6 is pulverized by the rotation of the pulverizing table 6 and the mill roller 7 pressed and rotated by a predetermined pressing force, and the pulverized granular material 8 is supplied to the blowing port 9. From the casing 1 through the opening 13 of the slit cone 11, is guided from the outer peripheral side to the rotating blades 16 of the rotary classifier 14, and is classified. The fine powder 8a is supplied from a fine powder delivery pipe 15 to a burner or the like of a boiler (not shown).

At this time, when the coal supply command 22 is input to the motor 19, the amount of coal supplied to the mill by the metering conveyor 20 is controlled.

Further, the coal supply command 22 is input to a coal output controller 23, and the coal output controller 23 supplies coal based on the coal supply command 22 as shown in FIG. Since the quantity control command 24 is output to the subtractor 25, the subtractor 25 subtracts the flow rate detection signal 30 from the flow meter 29 and the coal supply quantity control command 24, and the deviation is eliminated. The primary air conditioning damper 2 by the PI controller 26
8 is adjusted to control the primary air flow rate.

Further, a coal feed control command 24 from the coal output controller 23 is input to a rotation speed controller 31. The rotation speed controller 31 receives the coal feed control command as shown in FIG. 24
Is output to the electric motor 18 to control the rotation speed of the rotary classifier 14.

In the conventional device shown in FIG.
When the mill is driven by the coal feed amount command 22 as shown in FIG. 6A, the rotation speed controller 31 sets the rotary classification when the coal feed amount control command 24 increases (load increase) as shown in FIG. Machine 14
Is reduced so that the fine powder 8a is easily discharged, and when the coal supply amount control command 24 is reduced (load reduction), the rotational speed of the rotary classifier 14 is increased to make it difficult for the fine powder 8a to be discharged. So that the rotary classifier 14
Classifier rotation speed command 32 for controlling the rotation speed of
As shown in (B), the coal supply amount command 22 and the increase / decrease are in an inverse relationship.

[0014]

The conventional mill output control device shown in FIG. 4 does not consider the hardness of the coal 3 (difficulty of pulverization) at all, and therefore has the following problems. Had.

That is, conventionally, when the mill is driven by the coal feed amount command 22 as shown in FIG. 7A, the coal 3 is changed from coal A (coal of medium hardness) to coal B. In the case of changing to (soft coal), the pulverization of the coal 3 becomes easy, but the concentration of the fine powder 8a taken out from the fine powder delivery pipe 15 increases because the classifier rotation speed command 32 does not change at all. Therefore, as shown in FIG. 7 (C), the actual coal output 34 increases by the increment X with respect to the target coal output 33 shown by the solid line.

When the coal 3 changes from coal B (soft coal) to coal A (medium hardness coal), the coal 3 is difficult to be pulverized. The concentration of the fine powder 8a decreases, and the amount of coal output decreases.

Conventionally, a change in the hardness of the coal 3 can be determined by a change in the main steam temperature of the boiler. However, until the hardness of the coal 3 is found to change. Has a problem that the time delay is large and the control becomes unstable.

In view of the above situation, the present invention detects the lift of the mill roller and corrects the rotation speed of the rotary classifier based on the detected lift to stabilize the output of the mill even if the type of coal changes. It is an object of the present invention to provide a method and an apparatus for controlling the amount of coal output from a mill, which can control the coal output.

[0019]

According to the first aspect of the present invention, coal is pulverized by pressing a mill roller with a predetermined pressing force by a pressing device on a horizontally rotating pulverizing table, and the pulverized particles The body is levitated by primary air to classify and extract only fine powder with a rotary classifier, and the coal output is controlled by a coal feed control command based on the coal feed command. This is a mill coal output control method in which the rotation speed is controlled by a classifier rotation speed command based on the coal feed control command, wherein the lift amount of the mill roller is detected and the coal amount is detected by a decrease in the lift amount detection value. The increase in the number of rotations of the rotary classifier is detected by detecting that the hardness of the coal has decreased, and the rotation number of the rotary classifier is reduced by detecting that the hardness of the coal has increased due to the increase in the lift detection value. Control the coal output to the target output. Mill coal output control method characterized in that according to the.

According to a second aspect of the present invention, there is provided a pulverizing table that rotates horizontally, a mill roller that presses the pulverizing table with a predetermined pressure by a pressurizing device to pulverize coal, A rotary classifier that classifies and removes only fine powder from granules, a coal output controller that outputs a coal feed control command based on a coal feed command, and a classifier rotation speed based on a coal feed control command A mill output control device comprising: a rotation speed controller that outputs a command; a lift amount detector that detects a lift amount of a mill roller; and a rotation amount controller that rotates when a lift amount detection value from the lift amount detector decreases. A function generator that increases the rotation speed of the rotary classifier and outputs a rotation speed bias signal that decreases the rotation speed of the rotary classifier when the lift amount detection value increases, and a rotation speed bias signal from the function generator. Input to the rotation speed controller Mill coal output control device being characterized in that a multiplier for multiplying the coal feed amount control commands are,
It is related to.

According to a third aspect of the present invention, there is provided an adder for adding a wear amount calculation value from a wear amount calculator for calculating a wear amount of a mill roller and a grinding table to a lift amount detection value input to a function generator. 3. The apparatus according to claim 2, further comprising a vessel.
And a mill coal output control device.

According to the first and second aspects of the present invention, the lift amount of the mill roller is detected by the lift amount detector, and it is detected that the hardness of the coal has decreased due to the decrease in the detected lift amount, and the rotation is performed. The number of revolutions of the rotary classifier is increased by detecting the increase in the hardness of the coal due to the increase in the number of revolutions of the rotary classifier and the increase in the lift detection value. Is changed, the rotation speed of the rotary classifier is automatically corrected based on the lift amount detection value, and control can be performed so that the coal output matches the target coal output.

According to the third aspect of the present invention, the wear amount calculation value from the wear amount calculator which calculates the wear amount of the mill roller and the crushing table from past empirical data is added to the lift amount detector by the adder. Is added to the lift detection value input to the function generator from the above, the lift detection value can be detected more accurately, and the control of the mill coal output can be performed more accurately.

[0024]

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

FIG. 1 is a longitudinal sectional side view showing an example of an embodiment of the present invention applied to the roller mill of FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, a lift 7 of the mill roller 7 (between the crush table 6 and the mill roller) is applied to a pressing device 7a which presses the mill roller 7 with a predetermined pressing force on the horizontally rotating crush table 6. A lift detector 35 for detecting the layer thickness of the coal 3 to be bitten) is provided. The lift amount detector 35 shown in FIG. 1 shows a case where the lift amount detection value 36 is obtained from the movement stroke of the hydraulic cylinder of the pressurizing device 7a, and the lift amount S is indirectly measured.

A function generator 38 which receives a lift amount detection value 36 from the lift amount detector 35 and outputs a rotation speed bias signal 37 is provided.

As shown in FIG. 2, the rotation speed bias signal 37 increases the rotation speed of the rotary classifier 14 when the lift amount detection value 36 decreases, and turns the rotation type classifier when the lift amount detection value 36 increases. The number of rotations of 14 is reduced.

The rotation speed bias signal 37 from the function generator 38 is transmitted from the coal output controller 23 to the rotation speed controller 3.
1 is provided with a multiplier 39 for multiplying the coal feed amount control command 24 input to 1.

A wear amount calculator 40 for calculating the wear amount of the mill roller 7 and the crushing table 6 from past empirical data.
And a wear amount calculation value 41 from the wear amount calculator 40 is provided.
Is added to the lift amount detection value 36 input from the lift amount detector 35 to the function generator 38.

The operation of the above embodiment will be described below.

In the configuration shown in FIG. 1, when the coal feed amount command 22 is input to the motor 19, the coal feed amount by the weighing conveyor 20 is controlled. As shown in the figure, the primary air adjustment damper 28 is controlled by the coal feed amount control command 24 output from the coal output controller 23.
Is adjusted to control the flow rate of the primary air 10, and further, a classifier that receives a coal feed control command 24 from a coal output controller 23 and outputs from a rotation speed controller 31 as shown in FIG. 6. The rotation speed of the rotary classifier 14 is controlled by the rotation speed command 32.

At this time, the lift amount S (thickness of the coal 3) of the mill roller 7 pressed by a predetermined constant pressing force is related to the hardness of the coal 3, and when the coal 3 is hard, The mill roller 7 is pushed up to increase the lift amount S. Conversely, when the coal 3 is soft and easily pulverized, the mill roller 7
Lift amount S decreases.

Accordingly, the lift amount S of the mill roller 7 is detected by the lift amount detector 35, and it is detected that the hardness of the coal 3 has decreased due to the decrease in the detected lift amount detection value 36. The rotation speed of the rotary classifier 14 is controlled to decrease by detecting that the hardness of the coal 3 has increased due to an increase in the rotation speed of the 14 and an increase in the lift amount detection value 36.

That is, when the mill is driven by the coal supply command 22 as shown in FIG. 3A, the coal 3 is changed from coal A (medium hardness coal) to coal B (soft coal). 3B, the lift amount detection value 36 is reduced by 36 'as shown in FIG. 3 (B). In this case, the function generator 38 uses the function generator 38 as shown in FIG. The increased rotational speed bias signal 37 is obtained in accordance with the detected lift amount 36, which has been decreased, and the increased rotational speed bias signal 37 is multiplied by a multiplier 39 to the coal output controller 23.
Is multiplied by the coal feed control command 24 input to the rotation speed controller 31.

As a result, the classifier rotation speed command 32 output from the rotation speed controller 31 is increased by the increment 32 'as shown in FIG.
Since it becomes difficult to discharge a, the amount of coal output is suppressed, and control is performed so as to match the target coal output 33.

When the coal 3 is changed from coal B (soft coal) to coal A (coal of medium hardness), the coal 3 is hardly pulverized, and the lift amount shown in FIG. The detected value 36 increases in the opposite way, which causes the speed controller 3
The classifier rotation speed command 32 from 1 decreases in contrast to FIG. 3 (C), whereby the fine powder 8a is easily discharged, so that the coal output is increased, and the coal output is reduced as shown in FIG. 3 (D). Is controlled so as to match the target coal output 33 shown in FIG.

Further, a wear amount calculation value 41 from a wear amount calculator 40 which calculates the wear amount of the mill roller 7 and the crushing table 6 from past empirical data is added by the adder 42 to the lift amount detector 35. Since the addition to the lift amount detection value 36 input to the function generator 38 is performed, the lift amount detection value 36 can be detected more accurately, and the control of the mill coal output can be performed more accurately. .

[0039]

According to the first and second aspects of the present invention,
The lift amount of the mill roller is detected by the lift amount detector,
By detecting the decrease in the lift amount, the decrease in the hardness of the coal was detected, and the number of revolutions of the rotary classifier was increased, and the hardness of the coal increased due to the increase in the lift amount. The rotation speed of the rotary classifier is reduced by detecting this, so even if the coal type changes, the rotation speed of the rotary classifier is automatically corrected based on the detected lift amount. Thus, there is an effect that the coal output can be controlled so as to match the target coal output.

According to the third aspect of the present invention, the wear amount calculation value from the wear amount calculator configured to calculate the wear amount of the mill roller and the crushing table from past empirical data is calculated by the adder. Since the detection value is added to the lift amount detection value input from the detector to the function generator, the lift amount detection value can be detected more accurately, and the control of the mill coal output can be performed more accurately. effective.

[Brief description of the drawings]

FIG. 1 is a longitudinal side view showing an example of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a lift amount detection value and a rotation speed bias signal.

FIG. 3 shows the operation of the embodiment of the present invention.
(A) is a diagram showing an example of a coal supply command and an example of a change in coal type, (B) is a diagram showing an example of a detected lift amount,
(C) is a diagram showing an example of a classifier rotation speed command, (D)
Is a diagram showing an example of the amount of coal output.

FIG. 4 is a longitudinal sectional side view of a conventional roller mill.

FIG. 5 is a diagram showing a relationship between a coal supply amount command and a coal supply amount control command.

FIG. 6 is a diagram showing a relationship between a coal supply amount control command and a classifier rotation speed command.

7A and 7B are diagrams illustrating an operation of the conventional apparatus, in which FIG. 7A is a diagram illustrating an example of a coal supply command and an example of a change in coal type, and FIG. 7B is a diagram illustrating an example of a classifier rotation speed command. FIG. 1C is a diagram showing an example of the coal output.

[Explanation of symbols]

 Reference Signs List 3 Coal 6 Crushing table 7 Mill roller 7a Pressurizing device 8 Granular material 8a Fine powder 10 Primary air 14 Rotary classifier 22 Coal supply command 23 Coal output controller 24 Coal control command 31 Revolution controller 32 Classifier Revolution number command 33 Target coal output 35 Lift amount detector 36 Lift amount detection value 37 Revolution number bias signal 38 Function generator 39 Multiplier 40 Wear amount calculator 41 Wear amount calculation value 42 Adder S Lift amount

Claims (3)

[Claims] 1. A coal is pulverized by pressing a mill roller with a predetermined pressure on a horizontally rotating pulverizing table with a pressurizing device, and the pulverized powder is floated by primary air to form a rotary classifier. And only the fine powder is classified and taken out. The coal output is controlled by a coal feed control command based on the coal feed command, and the rotation speed of the rotary classifier is classified based on the coal feed control command. A method for controlling the amount of coal output from a mill, which is controlled by a rotation speed command of a mill, detects a lift amount of a mill roller, and detects that the hardness of the coal has decreased due to a decrease in the lift amount detection value. Increase the speed of the classifier,
A mill output characterized by controlling the coal output to a target coal output by detecting that the hardness of the coal has increased due to an increase in the lift detection value and reducing the number of revolutions of the rotary classifier. Coal quantity control method. 2. A pulverizing table that rotates horizontally, a mill roller that presses the pulverizing table with a predetermined pressure by a pressurizing device to pulverize coal, and classifies only fine powders from the powder particles floated by primary air. Rotary classifier that takes out and takes out, a coal output controller that outputs a coal feed control command based on the coal feed command, and a revolution control that outputs a classifier rotation speed command based on the coal feed control command And a lift amount detector for detecting a lift amount of a mill roller, and a rotation number of a rotary classifier when the lift amount detection value from the lift amount detector decreases. A function generator that outputs a rotation speed bias signal that increases and decreases the rotation speed of the rotary classifier when the lift amount detection value increases, and a rotation speed bias signal from the function generator is input to the rotation speed controller. The coal supply control command And a multiplier for calculating the coal output from the mill. 3. An adder for adding a calculated value of a wear amount from a wear amount calculator for calculating a wear amount of a mill roller and a crushing table to a detected lift amount input to a function generator. The mill coal output control device according to claim 2, wherein