JP2000140679A - Automatic water injecting device of coal bunker for pulverized coal mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent capacity of a pulverized coal mill from being deteriorated by avoiding unnecessary water injection when a lot of treating water contents are stuck to the surface of coal in a coal bunker and preventing excess water contents from being added to coal, viewed from an angle of use. SOLUTION: With respect to an automatic water injecting device of a coal bunker for a pulverized coal mill 1 for suitably injecting water to an outlet part of a coal bunker 9 through a water feeding pipe 17 to prevent the clogging by coal 5, there are provided a moisture calculating device 38 for calculating the treating water contents stuck to the surface of coal 5 fed to the mill 1 and for outputting a signal for requiring no injection 37 when the water contents are not less than a prescribed set value and a controller 19 for outputting an open command signal 20 for a water injection valve 18 only when it is discriminated that the whole plant is now being operated and this mill 1 is stopped without the signal 37 from the device 38 and based on operation signals 21, 22 from a plant control system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic water injection device for a coal bunker for a pulverized coal mill.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional general pulverized coal mill. In this type of pulverized coal mill 1, in a pulverized coal mill 1, a coal 5 dropped from an upper chute 2 onto a rotary table 3 is used. The pulverized coal 5 ′ is pulverized by a roller 4 that is pressed against a plurality of locations in the circumferential direction of the rotary table 3 so as to roll following the rotation of the rotary table 3, and the pulverized pulverized coal 5 ′ is placed around the rotary table 3. The air is conveyed upward by primary air 7 blown out from a large number of ports 6 provided in an annular shape, and sent from the top to a burner of a coal-fired boiler (not shown) through a cyclone type coarse powder separator 8. is there.

Here, the supply of the coal 5 to the chute 2 is performed by feeding coal 5 extracted from a lower part of a coal bunker 9 into a top opening of the chute 2 by a horizontal circulation type belt conveyor 10. This is performed by the machine 11.

The supply of the primary air 7 to each of the ports 6 is performed by a primary air supply pipe 13 connected to an air chamber 12 formed immediately below each of the ports 6. Mixing ratio adjustment dampers 14 and 15 mix cold air directly supplied from a high pressure ventilator (not shown) with hot air superheated by heat exchange with combustion gas of a coal-fired boiler.
Thus, the primary air 7 adjusted to the required temperature can be introduced into the air chamber 12 at an appropriate flow rate through the flow rate adjusting damper 16 by appropriately adjusting the ratio.

[0005] In such a pulverized coal mill 1,
When the operation is stopped, the moisture of the coal 5 in the coal bunker 9 decreases with time and dries, and the coals 5 may be stuck in the coal bunker 9 to cause clogging. In the vicinity of the water supply pipe 17, water can be appropriately supplied through a water supply pipe 17, and an opening command signal 20 is output from a control device 19 to a water supply valve 18 provided in the water supply pipe 17 to open the water supply valve 18. Is controlled.

That is, operation signals 21 and 22 from a plant control system are input to the control device 19. Based on the operation signals 21, the entire plant is currently operating and the pulverized coal mill 1 is in operation. Is determined to be stopped, an open command signal 20 is output to the water injection valve 18 of the water supply pipe 17.

FIG. 4 shows an example of a control circuit built in the control device 19, and one of the operation signals 21 inputted thereto indicates that all of the primary ventilators provided in the plant are stopped. And the other operation signal 22 indicates that the pulverized coal mill 1 is stopped.

Then, one operation signal 21 is inputted to an AND circuit 24 via a NOT circuit 23, and the other operation signal 22 is inputted to the AND circuit 24 as it is. When both of the signals 22 are input to the AND circuit 24, the AND circuit 24 outputs an AND signal 25.

That is, both of the operation signals 21 and 22 are A
The case where the pulverized coal mill 1 is inputted to the ND circuit 24 is a plant operating state in which all the primary ventilators are not stopped (the signal is lost by the NOT circuit 23 when all the units are stopped). It means that it is stopped.

In such a case, the AND signal 25 output from the AND circuit 24 is a one-shot 2
6 and a system input to another AND circuit 31.
The AND signal 29 output from the D circuit 31 is input to another one-shot 27 as a delay signal 29 'after a predetermined time via the ON delay timer 28, and the delay signal 29 output from the ON delay timer 28 'Is NOT
The signal is also input to the another AND circuit 31 via the circuit 30.

That is, when the AND signal 24 is output from the AND circuit 24, a pulse signal is output from one of the one shots 26 so as to continue for a predetermined set time. At the same time, the AND signal 25 from the AND circuit 24 and the delay signal 29 'from the NOT circuit 30 (at this time, the signal itself is generated by another AND circuit 31). (The signal of "1" has already been input by the NOT circuit 30 because it is in the state of "0"), and the AND signal 29 is newly output to the on-delay timer 28, The on-delay timer 28 starts counting a predetermined time delay, and after a predetermined time, a delay signal 29 'is output toward the other one-shot 27, and the other one-shot 27 is output. Pulse signal to continue from preparative 27 by a predetermined set time period is output OR circuit 32
Is output as an open command signal 20 via the.

Here, when the delay signal 29 ′ is output from the on-delay timer 28 to the other one-shot 27, the delay signal 29 ′ is simultaneously output to the AND circuit 31.
9 'is returned to the AND circuit 3 by the NOT circuit 30.
1 is lost, the AND signal 29 from the AND circuit 31 to the on-delay timer 28 disappears,
As a result, the AND operation by the NOT circuit 30 is immediately performed.
The signal input to the circuit 31 is restored and the on-delay timer 2
The count of 8 is reset and a new count is started.

The signal duration set in each one-shot 26, 27 means the opening operation time of the water injection valve 18 necessary for performing one water injection, and is usually about 60 seconds. The signal delay time set in the on-delay timer 28 may be sufficiently determined by the wetness of the inner wall surface of the coal bunker 9 even after the water is injected into the coal bunker 9 without performing the next injection. It means an open command interval to the water injection valve 18 that is empirically determined that the clogging of the coal 5 can be prevented, and usually about 4 hours.

When the entire pulverized coal mill 1 is currently operating and the pulverized coal mill 1 is stopped, the control device 19 sends the water supply valve of the water supply pipe 17 based on the operation signals 21 and 22 from the plant control system. An opening command signal 20 is output to the fuel injection valve 18 for a predetermined opening operation time to open the water injection valve 18, whereby water is injected into the coal bunker 9 and the coal 5 is discharged.
After that, when a time corresponding to a predetermined opening command interval elapses while the pulverized coal mill 1 is stopped, the water injection valve 18 is opened again and water is injected into the coal bunker 9. Will be done.

In FIG. 3, reference numeral 33 denotes a coal feed amount detector attached to the coal feeder 11 for detecting the feed amount to the pulverized coal mill 1;
Is a flow rate detector attached to the primary air supply pipe 13 and detects the flow rate of the primary air 7 introduced into the pulverized coal mill 1. 35 is a flow rate detector attached to the primary air supply pipe 13 and detects the mill inlet temperature of the primary air 7. A first temperature sensor 36 is a second temperature sensor attached to the top of the mill to detect the temperature of the primary air 7 at the mill exit.

[0016]

However, in such conventional means, the amount of treated water adhering to the surface of the coal 5 in the coal bunker 9 (the primary air 7 in the pulverized coal mill 1).
Water is to be injected irrespective of the amount of water that must be dried), so that when the coal storage yard is raining, the coal 5 put into the coal bunker 9 gets wet and is not wet enough. Despite having a treated water content (sliding is good and clogging is unlikely to occur), unnecessary water is injected and extra water is added to the coal 5 in operation. Therefore, there is a possibility that the performance of the pulverized coal mill 1 may be reduced.

The present invention has been made in view of the above-described circumstances, and avoids unnecessary water injection when the amount of treated water adhering to the surface of coal in a coal bunker is large. The purpose is to prevent the pulverized coal mill from deteriorating in capacity by preventing it from being added to coal.

[0018]

SUMMARY OF THE INVENTION The present invention relates to an automatic water injection device for a coal bunker for a pulverized coal mill, in which water is suitably injected near the outlet of a coal bunker through a water supply pipe to prevent clogging of the coal. A moisture calculating device for calculating the amount of treated water adhering to the coal surface supplied to the pulverized coal mill and outputting a water injection unnecessary signal when the treated water amount is equal to or greater than a predetermined set value; It is directed to the water supply valve of the water supply pipe only when it is determined that there is no water injection unnecessary signal from the calculation device and that the entire pulverized coal mill is currently operating and the pulverized coal mill is stopped based on the operation signal from the plant control system. And a control device for outputting an open command signal.

Therefore, according to the present invention, when the water content of the coal calculated by the moisture calculating device is equal to or more than a predetermined set value, the water injection unnecessary signal is output to the control device. When the number of coals is sufficiently large and there is little concern about coal clogging, the opening command signal is not output from the control device, and unnecessary injection of water into the coal bunker is avoided.

Further, when the amount of treated water of the coal calculated by the moisture calculating device is smaller than a predetermined set value, the output of the water injection unnecessary signal to the control device is lost. When it is determined that the entire plant is currently operating and the pulverized coal mill is stopped, an open command signal is output to the water supply valve of the water supply pipe, and the water supply valve is opened for a predetermined time. Accordingly, water is injected into the vicinity of the exit of the coal bunker to prevent coal clogging.

Further, in the present invention, a coal feed amount detector for detecting a coal feed amount to a pulverized coal mill, a flow detector for detecting a flow rate of primary air introduced into the pulverized coal mill, and a primary air mill A first temperature detector for detecting the inlet temperature, a second temperature detector for detecting the mill outlet temperature of the primary air, and a third temperature detector for detecting the outside air temperature, from these various detectors It is possible to input the detection signal to the moisture calculating device to calculate the amount of treated water.

[0022]

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

FIGS. 1 and 2 show an example of an embodiment of the present invention, and the portions denoted by the same reference numerals as in FIGS. 3 and 4 represent the same components.

As shown in FIG. 1, in this embodiment, the amount of treated water adhering to the surface of the coal 5 supplied to the pulverized coal mill 1 is calculated, and water is injected when the treated water amount is equal to or more than a predetermined set value. A moisture calculating device 38 that outputs an unnecessary signal 37 is provided, and a water injection unnecessary signal 37 from the moisture calculating device 38 is provided.
To the control device 19, there is no input of the water injection unnecessary signal 37, and the operation signal 2 from the plant control system is
Only when it is determined that the entire plant is currently operating and the pulverized coal mill 1 is stopped based on 1 and 22, the control device 19 outputs the open command signal 20 to the water injection valve 18 of the water supply pipe 17. It is so.

In particular, in the moisture calculating device 38 of the present embodiment, a coal feed amount detector 33 for detecting a feed amount to the pulverized coal mill 1;
A flow detector 34 for detecting the flow rate of the primary air 7 introduced into the pulverized coal mill 1, a first temperature detector 35 for detecting the mill inlet temperature of the primary air 7, and a mill outlet temperature of the primary air 7 A second temperature detector 36, and a third temperature detector 3 arranged at an appropriate place in the plant building and detecting an outside air temperature
9, various detection signals 33a, 34a, 35a, 3
6a and 39a are inputted to calculate the amount of water to be treated. More specifically, the amount of coal 5 is calculated by the following equation.
Is calculated.

[0026]

(Equation 1) Here, M is the treated water content (%) A is the flow rate of the primary air 7 introduced into the pulverized coal mill 1 (kg /
H) Ti is the mill inlet temperature of the primary air 7 (° C) To is the mill outlet temperature of the primary air 7 (° C) Tc is the outside air temperature (° C) corresponding to the surface temperature of the coal 5 CF is the supply to the pulverized coal mill 1 Coal content Ho is 595 + 0.46 × To: Mill exit enthalpy (k
Cc is the specific heat of coal 0.25 (kcal / kg ° C) Ca is the specific heat of air 0.245 (kcal / kg ° C) Qm is the heat input of the mill motor.

For example, when the amount of treated water M is calculated to be equal to or greater than 12%, it is determined that water injection is unnecessary, and a water injection unnecessary signal 37 is output to the control device 19.

Incidentally, a mechanism for calculating the amount M of treated water adhering to the surface of the coal 5 of this type may be already provided in the plant for performing control corresponding to the type of coal and the like. In this case, the moisture content calculating device 38 may be capable of appropriately outputting the water injection unnecessary signal 37 by inputting and diverting data obtained by calculating the treated water amount M.

Further, the method of calculating the amount of treated water M is not limited to the method of calculation using the above equation,
3. The flow rate detector 34, the first temperature detector 35, the second temperature detector 36, the third temperature detector 39, etc. are generally equipped as existing equipment necessary for performing various operation controls. Therefore, these detection signals 33a, 34a, 35
If a, 36a, and 39a are used, implementation by relatively simple equipment improvement becomes possible.

FIG. 2 shows an example of a control circuit built in the control device 19. In this control circuit, a water injection unnecessary signal 37 from the moisture calculating device 38 is ANDed via a NOT circuit 40. It is substantially the same as the control circuit shown in FIG. 4 except that it is input to the circuit 24.

When the water content M of the coal 5 calculated by the humidity calculating device 38 is, for example, 12% or more, it is determined that water injection is unnecessary, and a water injection unnecessary signal 37 is sent to the control device 19. Output signal, the water injection unnecessary signal 37
Is inverted from the state of "1" to the signal of "0" by the NOT circuit 40, the signal input of the water injection unnecessary signal 37 to the AND circuit 24 disappears, and the AND signal 25 is output from the AND circuit 24. As a result, the output of the opening command signal 20 from the control device 19 is not performed, and unnecessary injection of water into the coal bunker 9 is avoided.

When the water content M of the coal 5 calculated by the moisture calculating device 38 is smaller than, for example, 12%, the output of the water injection unnecessary signal 37 to the control device 19 disappears. The input signal to the AND circuit 24 is restored from the "0" state in which the input signal has disappeared by the NOT circuit 40 in the device 19 to the "1" signal, and the operation signals 21 and 22 are restored in this state. When it is determined by the control device 19 that the entire plant is currently operating and the pulverized coal mill 1 is stopped, an open command signal 20 is output to the water injection valve 18 of the water supply pipe 17 to output the water injection valve 18. Is opened only for a predetermined time, whereby water is injected into the vicinity of the outlet of the coal bunker 9 to prevent the coal 5 from being clogged.

Since the inner wall surface of the coal bunker 9 is wet for a while after the water injection and the clogging hardly occurs irrespective of the water content of the coal 5, an open command is directed to the injection valve 18 of the water supply pipe 17. After the signal 20 is output, the next water injection is performed after a predetermined non-output interval has elapsed.

Therefore, according to the above embodiment, the coal bunker 9
Unnecessary water injection can be avoided when the amount of treated water adhering to the surface of the coal 5 in the inside is large, so that excess water is not added to the coal 5 in operation and the capacity of the pulverized coal mill 1 is reduced. The drop can be prevented.

The automatic water injection device for a coal bunker for a pulverized coal mill of the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the present invention. Of course.

[0036]

According to the above-described automatic water injection apparatus for a coal bunker for a pulverized coal mill of the present invention, unnecessary injection of water is avoided when the amount of treated water adhering to the surface of coal in the coal bunker is large. Therefore, it is possible to obtain an excellent effect that it is possible to prevent the operation of excess water from being added to the coal and to prevent a reduction in the performance of the pulverized coal mill.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a control circuit built in the control device of FIG.

FIG. 3 is a block diagram showing a conventional example.

FIG. 4 is a block diagram illustrating an example of a control circuit built in the control device of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulverized coal mill 5 Coal 7 Primary air 9 Coal bunker 13 Primary air supply pipe 17 Water supply pipe 18 Water injection valve 19 Control device 20 Open command signal 21 Operation signal 22 Operation signal 33 Coal supply amount detector 33a Detection signal 34 Flow detector 34a Detection signal 35 First temperature detector 35a Detection signal 36 Second temperature detector 36a Detection signal 37 Water injection unnecessary signal 38 Moisture calculation device 39 Third temperature detector 39a Detection signal

Claims (2)

[Claims] An automatic water injection device for a coal bunker for a pulverized coal mill, wherein water is appropriately injected near an outlet portion of a coal bunker through a water supply pipe to prevent clogging of the coal. A moisture calculating device that calculates a treated water amount attached to the surface of the coal to be processed and outputs a water injection unnecessary signal when the treated water amount is equal to or more than a predetermined set value; and a water injection unnecessary signal from the moisture calculating device. And a control device that outputs an open command signal to the water supply valve of the water supply pipe only when it is determined that the entire plant is currently operating and the pulverized coal mill is stopped based on the operation signal from the plant control system. An automatic water injection device for a coal bunker for a pulverized coal mill, comprising: 2. A coal feed amount detector for detecting a coal feed amount to the pulverized coal mill, a flow rate detector for detecting a flow rate of primary air introduced into the pulverized coal mill, and a mill inlet temperature of the primary air. A first temperature detector, a second temperature detector for detecting a primary air mill exit temperature, and a third temperature detector for detecting an outside air temperature are provided. The automatic water injection apparatus for a coal bunker for a pulverized coal mill according to claim 1, wherein the apparatus is configured to calculate the amount of water to be processed by inputting the same to a minute calculation apparatus.