JPH10192730A - Pulverizing roll load hydraulic control device of coal pulverizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a suitable roll lift for a change in the property of coal with respect to a pulverizing roll load hydraulic control device of a coal pulverizer. SOLUTION: In this device, a function generator 4c inputs a reference load hydraulic setting signal 4c' to an adder 9 by a signal of a coal fed quantity transmitter 1. In system A, a subtractor 5d to which a signal of a roll lift transmitter 3 and a roll lift set value 10 are inputted outputs a roll lift deviation signal 5d' to a controller 6d, which outputs a load hydraulic set value correction signal 6d', which is added to the adder 9. The adder 9 inputs a post load hydraulic set value correction signal 9' to subtractor 5c. The subtractor 5c outputs a deviation between this signal 9' and a signal from a pulverizing roll load hydraulic transmitter 2 to control hydraulic control valves 8g, and 8h and 81 of a system B and a system C respectively. Since correction from deviation of a roll lift is added even to a change in property of coal by the system A, the suitable roll lift is always kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure control device for a crushing roll of a coal crusher applied to a boiler using coal as a fuel.

[0002]

2. Description of the Related Art FIGS. 2 and 3 show a system diagram of a conventional grinding roll load hydraulic control device for a coal grinding machine. In the example of FIG. 2, the control device is of a type that sets the load hydraulic pressure based on the coal supply amount. The measured coal supply amount value from the coal supply amount transmitter 1 is input to the function generator 4 a, and the function generator 4 a Outputs a load hydraulic pressure setting signal 4a '. Further, a crush roll load hydraulic signal from the crush roll load hydraulic transmitter 2 is input to the subtractor 5a. There are two ways to control the control valve. In the system D, first, the subtractor 5a outputs a deviation between these values, which is used as an input to the controller 6a. The controller 6a is, for example, a proportional + integral calculator, and outputs an opening command signal for the load hydraulic pressure control valve 8a.

Another method of FIG. 2 is to input a deviation signal, which is the output of a subtractor 5a, to high / low detectors 7a and 7b and detect a high-side signal, as in the system E. In this case, the control valve 8b on the load hydraulic pressure increasing side is opened, and when the signal on the low hydraulic pressure side is detected, the control valve 8c on the load hydraulic pressure decreasing side is opened.

In the example shown in FIG. 3, there is a control device of a system for setting a load hydraulic pressure based on a roll lift amount (thickness of a coal layer between a coal tray and a crushing roll).
The roll lift measurement value from the roll lift transmitter 3 is input to the function generator 4b, and the function generator 4b outputs the load hydraulic pressure setting signal 4b '. Further, a crush roll load hydraulic signal from the crush roll load hydraulic transmitter 2 is input to the subtractor 5b. Hereinafter, the system F corresponds to the system D in FIG. 2, and the system G corresponds to the system E, and their operations are the same as those in FIG.
Controls the load hydraulic pressure control valve 8d, and the signals from the high / low detectors 7c and 7d control the hydraulic pressure increase control valve 8e and the hydraulic pressure decrease control valve 8f.

[0005]

In the conventional load oil pressure setting method shown in FIG. 2, since the load oil pressure setting is determined in accordance with the amount of coal supplied, when the properties (particularly the hardness) of the coal change, Even if the amount of coal supplied is the same, the value of the roll lift (the thickness of the amount of coal on the crushed surface) is greatly different. When the roll lift value is too small, it promotes the progress of the wear of the roll, and when the roll lift value is too large, the load hydraulic pressure is insufficient with respect to the thickness of the coal seam. It will be. Therefore, in the conventional method, there is a problem that it is necessary to change the function of the function generator 4a for setting the load hydraulic pressure every time the property of the coal changes.

Further, in the conventional load hydraulic pressure setting method shown in FIG. 3, since the load hydraulic pressure setting is determined according to the roll lift, the roll lift value becomes too small or too large as shown in the example of FIG. However, since the load oil pressure changes after the roll lift changes, there is a delay in the change in the load oil pressure with respect to the change in the coal supply amount (for example, an increase in the coal supply amount → inside the coal pulverizer). Increasing coal quantity → increasing roll lift → increasing hydraulic pressure → increasing pulverized coal quantity at the coal pulverizer outlet).

Accordingly, in controlling the fuel flow rate of the boiler,
The actual change in the fuel flow rate (pulverized coal quantity change) is delayed with respect to the fuel flow rate change (coal supply change) demand.
There is a problem that adversely affects the operation dynamics of the boiler.

[0008]

The present invention provides the following means in order to solve the above-mentioned problems. That is, the present invention
A load control unit that outputs a load hydraulic pressure set value as a function based on the coal supply amount of the coal crusher and controls a hydraulic control valve with the load hydraulic pressure set value in a crushing roll load hydraulic control device of the coal crusher. The present invention provides a pulverizing roll load hydraulic control device for a coal pulverizer, wherein a means for calculating a deviation between a measured value and a roll lift set value is provided, and the load hydraulic pressure set value is corrected with the deviation.

The present invention employs a method of determining the load hydraulic pressure setting in accordance with the coal supply amount (that is, the load hydraulic pressure is immediately changed by the change in the coal supply amount), but a roll lift (a portion sandwiched between the coal receiving tray and the crushing roll). The thickness of the coal seam is measured, and the load hydraulic pressure setting is corrected based on the deviation between the measured value and the roll lift setting value (appropriate coal seam thickness for crushing efficiency). Even if the amount of coal supply changes and the value of the roll lift differs, the operation of the coal crusher can always be performed while maintaining an appropriate roll lift. In addition, the load hydraulic pressure is immediately changed in response to the change in the coal supply amount, and the load change from the change in the roll lift is also added as a positive operation (for example, increase in the coal supply amount → load hydraulic pressure set value → roll lift increase → load hydraulic pressure). Since the setting correction is increased), it also has an advantageous effect on the boiler operation dynamic characteristics.

[0010]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a system diagram of a crushing roll load hydraulic control device of a coal crusher according to one embodiment of the present invention. In the present embodiment, a circuit for measuring the roll lift and correcting the load hydraulic pressure setting based on the deviation from the roll lift set value is added to the conventional method shown in FIG. explain.

In FIG. 1, 1 is a coal supply transmitter, 2
Is a grinding roll load hydraulic transmitter, 3 is a roll lift transmitter, 4c is a function generator, 5c and 5d are subtractors, 6c and 6
d is a controller, for example, a proportional + integral calculator. 7e and 7f are high / low detectors, 8g, 8h and 8i are hydraulic pressure control valves, 8g is a load hydraulic pressure control valve, 8h is a hydraulic pressure increase control valve, and 8i is a hydraulic pressure decrease control valve. 9 is an adder, 10
Is a roll lift set value, and 11 is an upper and lower limiter.

In the above configuration, the characteristic part of the present invention resides in the system indicated by the symbol A, and the reference load hydraulic pressure setting signal c 'is supplied from the function generator 4c to which the measurement value of the coal supply transmitter 1 is input. It is output and becomes the input of the adder 9 of the system A.

Further, in the system A, a subtractor 5d which receives the measured value of the roll lift transmitter 3 and the roll lift set value 10 as inputs receives a deviation of these values, that is, a roll lift deviation 5.
d 'is output and becomes an input signal of the controller 6d. Controller 6
d is, for example, a proportional + integral calculator, and outputs a load hydraulic pressure set value correction signal 6d '. The load hydraulic pressure set value correction signal 6d 'is input to the adder 9 through an upper / lower limiter 11 for limiting the correction amount. The adder 9 outputs the sum of the load oil pressure setting signal 4c 'and the load oil pressure set value correction signal 6d' as the reference, as the load oil pressure set value corrected signal 9 '.

The load hydraulic pressure control valve is controlled in two ways. The subtractor 5c which receives the load hydraulic pressure set value corrected signal 9 'and the measured value 2' of the crushing roll load hydraulic pressure transmitter 2 as inputs is used for these values. Is output.

First, in the system B, the deviation signal 5c 'is input to the controller 6c. The controller 6c is, for example, proportional +
It is an integral calculator and serves as an opening command signal for the load hydraulic pressure control valve 8g.

As another method, in the system C, the deviation signal 5c 'output from the subtractor 5c is input to the high / low detectors 7e and 7f. The control valve 8h is set to the opening operation, and when the low side is detected, the control valve 8i for reducing the load hydraulic pressure is set to the opening operation.

In the embodiment described above, the load hydraulic pressure setting signal 4c 'which is a reference based on the function of the coal supply amount.
By adding the load hydraulic pressure set value correction signal 6d 'based on the roll lift deviation, the coal crusher can be operated while always maintaining an appropriate roll lift even when the properties of the coal change. In addition to the change in the coal supply amount, the load hydraulic pressure is immediately changed, and the load change from the roll lift change is also added as a normal operation (for example, the coal supply amount increases → the reference load hydraulic pressure setting signal 4c ′ increases → Roll lift increase → load hydraulic pressure set value correction signal 6d 'increase)
It also works favorably in terms of boiler operation dynamics.

[0018]

As described above, in the roll hydraulic pressure control apparatus for a coal crusher according to the present invention, the roll lift is measured with respect to the load hydraulic pressure set by the function of the coal supply amount, and this measurement is performed. By adding a correction to the load oil pressure set value from the deviation between the set value and the roll lift set value, it is possible to always maintain an appropriate roll lift (appropriate pulverized surface coal layer thickness on pulverization efficiency) against changes in coal properties. The operation of the coal crusher becomes possible. In addition, the load hydraulic pressure is immediately changed in response to the change in the coal supply amount, and a correction signal from the roll lift deviation is added as a normal operation, so that improvement in the boiler operation dynamic characteristics can be expected.

[Brief description of the drawings]

FIG. 1 is a system diagram of a pulverizing roll load hydraulic control device of a coal pulverizer according to one embodiment of the present invention.

FIG. 2 is a system diagram of a conventional crushing roll load hydraulic control device of a coal crusher, showing a control method based on a coal supply amount.

FIG. 3 is a system diagram of a conventional crushing roll load hydraulic control device of a coal crusher, showing a control method based on a roll lift.

[Explanation of symbols]

 1 Coal supply amount transmitter 2 Crush roll load hydraulic transmitter 3 Roll lift transmitter 4c Function generator 5c, 5d Subtractor 6c, 6d Controller 7e, 7f High / low detector 8g, 8h, 8i Hydraulic control valve 9 Addition Container 10 Roll lift set value 11 Upper and lower limiter

Claims (1)

[Claims] A crushing roll load hydraulic pressure control device for a coal crusher that outputs a load hydraulic pressure set value as a function based on the coal supply amount of the coal crusher and controls a hydraulic pressure control valve with the load hydraulic pressure set value. Wherein a means for calculating a deviation between a measured value of the roll lift and a set value of the roll lift is provided, and the load hydraulic pressure set value is corrected with the deviation.