JP3124111B2 - Coal mill control equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal mill control device applied to a coal-fired boiler.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 2 shows a mechanical system diagram of a conventional coal mill for pulverizing coal for a coal-fired boiler. The mill roller 1 is connected to a piston rod 4 of a cylinder 5 via an arm 3. The piston rod 4 has a roll lift detector 10.
Is provided.

The cylinder 5 is supplied with journal oil pressure from an oil tank 6 via a pump 7 and a control valve 8.
Further, a pressure detector 9 for detecting a journal oil pressure is provided at an inlet of the cylinder 5. In the figure, reference numeral 2 denotes a trunnion shaft, and 11 denotes an accumulator.

FIG. 3 is a block diagram of a conventional control device of a mill roll lift program type. The output signal 10s of the roll lift detector 10 is passed through a function generator 02 to a subtractor 0.
5 The output signal 9s of the pressure detector 9 is sent to the subtractor 05. The output of the subtractor 05 is sent to the control valve 8 via the controller 06.

In the above, the function generator 02 receives the roll lift signal 10s and receives the journal oil pressure setting signal 02s
And sends it to the subtractor. The subtracter 05 receives the journal oil pressure setting signal 02s and the journal oil pressure signal 9s, and sends a deviation signal to the controller 06. The controller outputs the operation signal of the control valve by the P1 calculation and sends it to the control valve 8. The control valve 8 opens and closes according to the input, and the journal oil pressure of the cylinder 5 is adjusted.

FIG. 4 shows a block diagram of another conventional control device of the coal supply program type. Function generators 12, 13,... For receiving the mill coal supply signal 15s are provided for each type of coal. The output of each of the function generators 12, 13,... Is sent to a subtractor 19 via a switch 14 and a function generator 16 in that order. The subtractor further receives the journal oil pressure signal 9s,
The output is sent to the control valve 8 via the controller 20.

In the above, each of the function generators 12, 13,
.. Input a mill coal feed signal 15 s and output a mill load signal 14 s corresponding to the type of coal, respectively. These function generators are designed so that the mill load differs depending on the coal type, so that the setting can be changed depending on the coal type, and the functions of the mill supply amount and the mill load for each coal type are programmed. .

The switch 14 selects the output of the function generator for the type of coal currently being fired in the boiler, and outputs a mill load signal 14 s corresponding to the type of coal.

The function generator 16 receives the mill load signal 14s and outputs a mill journal oil pressure setting signal 16s.
The mill journal oil pressure setting signal 16s is input to the subtractor 19 together with the journal oil pressure signal 9s. Subtractor 1
An output signal (deviation signal) from 9 becomes an input signal of the controller 20. The P1 calculation is performed by the controller 20, an operation signal of the control valve is output, and sent to the control valve 8. The control valve 8 opens and closes according to the input, and the journal oil pressure of the cylinder 5 is adjusted.

[0010]

Due to changes in the fuel situation, the demand for a high load change rate as a middle operation thermal power is also increasing in a coal-fired thermal power plant that has been operating under a base load. Coal-fired power plants use coal that has been pulverized by a pulverizer (mill) as fuel, and in order to achieve a high rate of load change, the mill has a fast response and can cope with many types of coal. A control unit is required.

The above-mentioned conventional mill roll lift program type controller can be applied even if the type of coal is changed. However, since the oil pressure does not change until the lift changes, there has been a problem in response to a load change.

On the other hand, the control unit of the coal supply program type has a good transient response because the oil pressure changes with the change of the coal supply.
However, it is necessary to change the setting program of the type of coal being fired each time the type of coal is switched, and when new coal is fired, operator intervention such as re-creating the set values is required.

[0013]

The present invention employs the following means to solve the above-mentioned problems.

That is, in a hydraulically operated coal mill, a second function generator for receiving a mill coal supply signal and outputting a preceding signal of the journal oil pressure of the coal mill in a predetermined coal type, A first function generator that receives a quantity signal and outputs a setting signal of a roll lift of the coal mill, and outputs a difference between the output signal of the first function generator and the roll lift signal of the coal mill. A first subtractor, a first controller receiving an output of the first subtractor and outputting a control signal, and an addition receiving outputs of the first controller and the second function generator A second subtractor that receives the output of the adder and the journal oil pressure signal of the coal mill and outputs a difference therebetween, and a second subtractor that receives the output of the second subtractor and outputs an operation signal to the control valve. And a controller.

[0015]

In the above means, the first function generator receives the mill coal feed signal and outputs a setting signal of the roll lift of the coal mill . The first subtractor receives the roll lift setting signal and the coal mill roll lift signal and outputs the difference (deviation signal). The first controller receives the deviation signal and calculates and outputs a control signal that reduces the deviation signal.

The second function generator receives the mill coal feed signal and receives a value of the coal mill journal oil pressure for a given coal type.
Output a row signal. The adder receives the preceding signal and a control signal from the first controller, adds them, and outputs the result. Second
Receives the output of the adder and the journal pressure signal of the coal mill and outputs the difference (deviation signal). The second controller receives the deviation signal, calculates and outputs an operation signal of the control valve that reduces the deviation signal, and sends the operation signal to the control valve. The control valve opens and closes in response to the signal and regulates the journal oil pressure for operating the rolls of the coal mill.

In this way, the journal oil pressure is automatically and responsively adjusted according to the amount of coal supplied and the type of coal.

[0018]

FIG. 1 shows an embodiment of the present invention. The parts described in the conventional example are assigned the same reference numerals, and the description thereof will be omitted. The parts related to the present invention will be mainly described.

The mill coal feed signal 15 s is sent to first and second function generators 31 and 32. The first subtractor 33 receives the subtraction of the mill roll lift signal 10s, and the output of the first function generator 31 is added. The output of the subtractor 33 is sent to the adder 35 via the first controller 34.

The output of the second function generator 32 is sent to an adder 35. The output of the adder 35 is added to the subtractor 37, and the mill journal oil pressure signal 9s is subtracted and input to the subtracter 37. The output of the subtractor 37 is sent to the control valve 8 via the second controller 38.

In the above, the first function generator 31 receives the mill feed rate signal 15s and receives the roll lift of the coal mill.
And it outputs a set signal 31s. First subtractor 33 is the b
And outputs a difference (deviation signal) between the control signal and the roll lift signal of the coal mill. The first controller 34 receives the deviation signal and calculates and outputs a control signal that reduces the deviation signal.

The second function generator 32 outputs the mill coal feed signal 1
5s, Coal mill journal of the specified coal type
It outputs a preceding signal 32s of hydraulic pressure . The adder 35 receives the preceding signal 32s and a control signal from the first controller 38,
It is added and output. The second subtractor 37 is the adder 3
And outputs the difference (deviation signal) in response to the output 5 and the journal oil pressure signal 9s of the coal mill. Second controller 38
Receives a deviation signal, calculates and outputs an operation signal 38s of the control valve that reduces the deviation signal, and sends it to the control valve 8. The control valve 8 opens and closes according to the signal, and adjusts the journal oil pressure for operating the roll of the coal mill.

In this way, even if the coal type is changed, the feedback function operates and can be automatically adapted without changing the setting. In addition, the change to the oil pressure corresponding to the coal supply amount also has better follow-up of the transient response than the roll lift program system due to the advance signal operation.

For example, when switching from coal A to coal B, the preceding operation is the same as that for coal A, but the feedback control of the mill roll lift automatically changes the hydraulic pressure to that corresponding to coal B. In the preceding operation, the operation at the time of the coal A is performed. However, since the hydraulic curve of both the coal A and the coal B is set to the right, the movement at the time of the coal A does not cause a serious problem.

In the case of the conventional roll lift program type,
Since the control is performed by the roll lift signal, the change in the hydraulic pressure is slow.
In the case of the coal supply program type, it takes time to change the setting. These disadvantages are eliminated.

[0026]

As described above, according to the present invention, the followability of the transient response is good, and even if the coal type is switched, the feedback function of the mill roll lift automatically (intervenes by the operator). (Without) the journal oil pressure is adjusted.

[Brief description of the drawings]

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

FIG. 2 is a mechanical system diagram of a conventional example.

FIG. 3 is a configuration block diagram of an example of the conventional example.

FIG. 4 is a configuration block diagram of another example of the conventional example.

[Explanation of symbols]

02, 12, 13, 16 Function generator 05, 19, 33, 37 Subtractor 06, 20, 34, 38 Controller (for example, PI controller, etc.) 31 First function generator 32 Second function generator 35 Adder

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B02C 15/00-15/16

Claims (1)

(57) [Claims] 1. A hydraulically operated coal mill, a second function generator for receiving a mill coal feed signal and outputting a preceding signal of a journal oil pressure of the coal mill for a predetermined coal type, and the mill coal feed. A first function generator that receives a quantity signal and outputs a setting signal of a roll lift of the coal mill, and outputs a difference between the output signal of the first function generator and the roll lift signal of the coal mill. A first subtractor that performs
A first controller that receives the output of the subtractor and outputs a control signal, an adder that receives the outputs of the first controller and the second function generator, an output of the adder and the coal A second subtractor that receives the mill hydraulic pressure signal of the mill and outputs a difference therebetween; and a second controller that receives an output of the second subtractor and outputs an operation signal to a control valve. And coal mill control equipment.