JPS6046338B2 - Combustion system automatic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic control device for a combustion system, and particularly to an automatic control device suitable for a coal boiler.

FIG. 1 shows a conventional example of an automatic control device for a coal boiler.

The turbine 2, which is the load side, requires steam with constant pressure and temperature. Steam pressure must also be kept constant in the boiler 1 itself. In order for the boiler 1 to always be able to supply steam at a constant pressure and temperature, the weight balance of water and energy balance within the boiler must be maintained. For this purpose, steam flow rate, pressure,
The temperature is detected by the detectors 4, 5, and 6, and the detected values are introduced into the control section 7. In response to this detected value, the control unit 7 controls the water supply control valve 3 to control the water supply amount, and also controls the vane operating device 10 to control the opening degree of the vane 9. The flow rate of the air sent through the fan 8 is controlled by controlling the opening of the vane 9, and the air is supplied to the inlet side of the mill 15. This maintains the weight balance of the water in the boiler and maintains the energy balance. Here, the amount of air at the inlet of the mill 15 and the amount of pulverized coal supplied to the boiler have a certain relationship as described later. Coal from the hopper 12 is sent by a coal feeder 13 to a mill 15 where it is crushed.

The crushed pulverized coal is supplied to the boiler 1 by air sent in by a fan 8 and is combusted. Next, control of the amount of coal supplied to the boiler 1 will be described.

The difference between the inlet air pressure and the output pressure of the mill 15 is detected by the mill differential pressure detector 16, and the detected differential pressure is used to measure the coal supply amount, and is used as a feedback signal of the coal supply amount controller 18. do. Further, the air amount controlled by the control unit 7 is detected by the air amount detector 11, and this is multiplied by a certain ratio by the ratio calculator 17 to obtain a coal supply amount setting signal, and the coal supply amount is It is input to the amount controller 18. The controller 18 obtains an operation signal based on the setting signal and the feedback signal, operates the coal feeder operating device 14, changes the speed of the coal feeder 3, and controls the amount of coal supplied. In such a configuration, if the quality of the coal is constant and the particle size of the pulverized coal pulverized by the mill 15 is constant, by measuring the mill differential pressure,
Although it is possible to accurately measure the amount of coal supplied, if the coal is of low quality, the particle size will not be constant and it will not be possible to accurately measure the amount of coal supplied.

That is, as shown in FIG. 2, the mill differential pressure differs even if the coal supply amount is the same, depending on whether the particles are coarse or fine.
Conversely, even if the differential pressure is the same, the actual amount of coal supplied differs depending on the particle size. Therefore, combustion instability occurs due to an imbalance between the amount of air and the amount of coal. An object of the present invention is to provide an automatic control device for a combustion system that enables stable combustion in a boiler.

The gist of the present invention is to correct the mill differential pressure based on the ratio between the mill differential pressure and the boiler output, and to control the coal fuel supply amount using the corrected mill differential pressure. .

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 3 shows an embodiment of the present invention.

The difference from FIG. 1 is that a first-order delay element 19, a divider 20, and a multiplier 21 are provided. The control unit 7 controls the boiler 1 based on the flow rate, pressure, and temperature detected by each of the detectors 4, 5, and 6, in addition to the control signal of the water supply control valve 3 and the control signal of the vane operating device 10.
The output steam is calculated, and this output is used as an input to the first-order delay element 19. The mill differential pressure detected by the mill differential pressure detector 16 is input to a divider 20 and a multiplier 21, respectively. The divider 20 inputs the mill differential pressure and the output of the first-order delay element 19, and calculates the ratio between the two. The primary delay element 19 is provided to correct the transmission delay from the mill to the boiler. The ratio calculated by the divider 20 becomes a parameter indicating the particle size of coal. Next, the multiplier 21
Multiply the mill differential pressure by the ratio obtained. As a result, the output of the multiplier 21 becomes the actual amount of coal supplied in consideration of the particle size, and this output is used as a feedback signal to the coal supply amount controller 21. The following movements are the same as those in FIG. 1, so they will be omitted. According to this embodiment, it is possible to accurately measure the amount of coal supplied, and accordingly, the amount of air is controlled in accordance with the amount of coal supplied, making it possible to perform good combustion in the boiler.

Note that the first-order lag element itself has a role of hollowing the transmission delay, and is not necessarily a first-order lag element depending on the configuration of the system itself.

The control section 7 includes a master control device, but a control section is provided separately from the master control device, and the boiler output is determined by the control section, and this is used as an input for the delay element. Good too. According to the present invention, it has become possible to achieve good combustion in the boiler.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional example, FIG. 2 is a diagram showing the relationship between coal supply amount and mill differential pressure, and FIG. 3 is a diagram showing an embodiment of the present invention. 1...Boiler, 2...Turbine, 7...
...Control unit, 10...Mil, 16...Mil differential pressure detector, 18...Coal supply amount controller, 20...
...Divider, 21...Multiplier.

Claims (1)

[Claims] 1. In a combustion system that includes a mill that receives coal and air as input, a boiler that burns pulverized coal sent from the mill, and a means that is driven by the amount of steam obtained by the boiler. , a means for measuring the mill differential pressure determined by the ratio of the inlet air pressure and the outlet pressure of the mill, and the mill differential pressure obtained based on the ratio of the mill differential pressure obtained by the means to the boiler output. An automatic control device for a combustion system, comprising means for correcting, and means for controlling the amount of coal supplied to the mill based on the corrected mill differential pressure obtained by the means.