JPH0310380B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the supply of pulverized coal fuel in a coal-fired boiler or the like.

A pulverized coal supply device for supplying pulverized coal fuel to a coal-fired boiler or the like is, for example, a conveyor-type coal feeder in which coal 2 from a bunker 1 is driven by a coal feeder motor 3, as shown in FIG. 4 to a pulverized coal device (hereinafter referred to as the mill) 5, and the mill 5
After being pulverized by a mill roller 6 provided at the bottom, the fuel is carried on an air flow 8 rising from a lower wind box 7, passes through a fuel pipe 9, and is supplied to a burner such as a boiler (not shown).

In such a pulverized coal supply device, the amount of pulverized coal fuel supplied to the boiler etc. is adjusted by controlling the rotation speed of the coal feeder motor 3 using the control signal A. As shown in the figure, a rotation speed detection meter a provided on the coal feeder motor 3
The detection signal b from the boiler etc. is compared with the master command e from the boiler etc. using the subtractor d, and the rotation of the coal feeder motor 3 is controlled via the controller e so that the difference is minimized. There is.

However, in the conventional method described above, the output of the mill 5 is only controlled by the rotation speed of the coal feeder motor 3, and the fuel flow rate at that time is not taken into account at all, and feedback control that takes the fuel flow rate into account is performed. was impossible. That is, as shown in FIG. 1, even if the number of revolutions of the coal feeder motor 3 is changed in an attempt to change the fuel flow rate, the coal is fed into the mill 5 and after being pulverized by the mill rollers 6. There is a long dead time and time delay before the air is carried by the air flow 8 and sent to a boiler etc. Therefore, in the conventional control method, for example, the rotation speed of the coal feeder motor 3 is controlled by a master command to increase fuel. Even if it is increased, it takes time for the fuel flow rate to increase to the desired amount, so the increase command continues, and even if the fuel flow rate reaches a predetermined amount and a master command to maintain that amount comes, Since a large amount of coal has already been put into the mill 5, the fuel flow rate continues to increase. Therefore, the master command to reduce the fuel comes into effect, but since it takes time for the fuel flow rate to decrease, the decrease command continues. In this way, in the conventional control system, even if the rotation speed of the coal feeder motor 3 is controlled to the required rotation speed, the mill 5
The required amount of output (fuel flow rate) cannot necessarily be obtained excessively, resulting in a problem of large fluctuations in the process amount.

In view of these points, the present invention measures the amount of coal fed into a mill by a coal feeder, estimates the mill output when the coal is sent out as pulverized coal from the mill at the measured value, The purpose is to eliminate process fluctuations and improve controllability by comparing and controlling the mill output estimation signal with a master command as a feedback signal.

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

FIG. 3 shows an example of the present invention applied to the pulverized coal supply device shown in FIG.
is passed through a feedback subtracter 11 and a feedback controller 12, and then further through a subtracter 13 and a controller 14 to be sent to the coal feeder motor 3 as a control signal A.
I am trying to input it into . Also, the coal feeder motor 3
The detection signal 16 of the rotation speed detector 15 provided at The input amount is measured, the measured signal 19 is introduced into the mill output estimation calculator 20, and the mill output estimation signal 21 is introduced into the feedback subtracter 11. The mill output estimation calculator 20 calculates the output of the mill 5 according to the current rotational speed of the coal feeder motor 3 by considering e ^-LS /1+TS L: dead time T: 1 time delay time constant S: Laplace operator. After the supplied coal is pulverized, the amount to be sent as pulverized coal from the mill 5 to a boiler etc. is estimated.

Therefore, in the above, for example, when the master command 10 to increase fuel is received, the rotation speed of the coal feeder motor 3 is increased via the feedback subtractor 11, feedback controller 12, subtracter 13, and controller 14. Ru. At this time, the detection signal 16 of the rotation speed detector 15
is introduced into the subtractor 13, and the rotational speed of the coal feeder motor 3 is adjusted to match the command 22 from the feedback controller 12. On the other hand, the rotation speed detection signal 16 is guided to a multiplier 18 to measure the amount of coal being fed into the mill 5 from the coal feeder 4,
This measurement signal 19 is input to a mill output estimation calculator 20. The mill output estimation calculator 20 is now mill 5.
Estimate the fuel flow rate when the coal input to the boiler is pulverized and sent to the boiler etc. as pulverized coal.
The mill output estimation signal 21 is fed back to the feedback subtractor 11 and compared with the master command 10. If master command 10 is larger,
The rotation speed of the coal feeder motor 3 continues to increase, but as soon as the mill output estimation signal 21 matches the master command 10, the rotation speed of the coal feeder motor 3 is maintained at that state. Therefore, the commanded flow rate of fuel is delivered from the mill 5 at a predetermined time without causing an oversupply of coal to the mill 5, and there is no possibility of fluctuations in the process.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be applied to supply control of pulverized coal fuel to various combustion furnaces other than boilers, and various other changes can be made without departing from the gist of the present invention. Of course, it is possible to add .

According to the pulverized coal fuel supply control method of the present invention described above, the output to be sent out as pulverized coal from the mill is estimated from the amount of coal being supplied to the mill by the coal feeder, and the output is fed back to the master command. Since the mill output is compared with the master command, it is possible to adjust the coal input amount of the coal feeder so that the mill output matches the master command, thereby eliminating process fluctuations and improving controllability.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a pulverized coal supply device;
FIG. 2 is an explanatory diagram of a conventional pulverized coal fuel supply control system, and FIG. 3 is an explanatory diagram showing an example of an apparatus for implementing the method of the present invention. 3 is a coal feeder motor, 4 is a coal feeder, 5 is a mill, 1
0 is the master command, 11 is the feedback subtractor,
12 is a feedback controller, 15 is a rotation speed detector, 18 is a multiplier, 19 is a measurement signal, 20 is a mill output estimation calculator, and 21 is a mill output estimation signal.

Claims (1)

[Claims] 1 In a method of feeding coal into a mill using a coal feeder and controlling the supply of fuel pulverized by the mill to a combustion furnace, the amount of coal fed into the mill using the coal feeder is measured, and the mill output based on the measured value is calculated. A method for controlling the supply of pulverized coal fuel, characterized in that the estimated mill output signal is used as a feedback signal to compare and control the mill output with a master command from the combustion furnace.