JPH10288331A - Fuel regulation valve travel control device of boiler provided with on-site single operation function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely perform the operation by providing arithmetic units such as a function generator to obtain the measurement valve travel signal from the moving average value of the Cv value and an adder to add the travel deviation signal from a switch to the prescribed travel to correct the travel deviation. SOLUTION: The Cv value 44 is inputted in a moving average calculator 46 to obtain the moving average value 46a, and the moving average value is inputted in a function generator 48 to obtain the measurement valve travel signal 50 from the function based on the reference value 47. The valve-travel command 20 and the measurement valve travel signal 50 are inputted in a subtracter 51 to obtain the travel deviation signal 52, and the travel deviation signal is inputted in a dead zone addition function generator 54 to obtain the dead zone. The travel deviation signal 52 is inputted in a switch 55 simultaneously with generation of the in-shop single operation command 17. The valve-travel deviation signal 52 is added to the prescribed travel 28 from a signal generator 29 of an on-site single operation switching circuit 26 through the adder to constantly correct the prescribed travel 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control valve opening control device for a boiler having an in-house isolated operation function.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a boiler for power generation. Fuel 1 such as oil or natural gas is supplied to a burner 5 of a boiler 4 via a fuel control valve 3 provided in a fuel pipe 2. The steam 6 that has been supplied and burned and generated by heating water in the boiler 4 is superheated through a superheater 7 and then supplied to a high-pressure steam turbine 9 through a turbine control valve 8. The generator 6 drives the generator 10 to generate electric power. The steam 6 output from the high-pressure steam turbine 9 is supplied to the reheater 1.
After being reheated by 1, the generator 10 is guided to a medium-pressure steam turbine 12 and a low-pressure steam turbine (not shown) to drive the generator 10 to generate power.

A fuel command 13 obtained from a boiler load command based on a generator command is input to a fuel control valve opening control device 14, and the fuel control valve opening control device 14 controls the fuel command 13 based on the fuel command 13. Thus, the opening of the fuel control valve 3 is controlled. Further, a fuel flow rate 16 detected by a flow meter 15 provided in the fuel pipe 2 is input to the fuel control valve opening control device 14.

[0004] In the above-described power generation boiler 4, when the power transmission is stopped due to an accident in a power transmission system for supplying the generated electricity or an accident related to a substation, an in-house independent operation command 17 is issued. (Fast Cut
Back), a function is provided for switching the boiler 4 to the in-house isolated operation.

[0005] In-station alone operation, when the power transmission is stopped due to a power transmission system accident or a substation-related accident, etc., the power transmission system load is disconnected from the steam turbines 9 and 12 and the boiler 4 (power station) side. The boiler 4 and the steam turbines 9 and 12 are operated with a minimum load by narrowing down the fuel control valve 3 to a specified opening (3% to 5%) for obtaining only necessary minimum power generation, and the power transmission system and the substation When the accident related to the place is restored, the load on the boiler 4 is immediately increased so that required electric power can be supplied.

FIG. 6 shows an example of the fuel control valve opening control device 14. The fuel control valve opening control device 14 controls the fuel command 13 and the flow rate from a flow meter 15 provided in the fuel pipe 2. A subtracter for subtracting the fuel flow rate from the fuel flow to obtain a deviation signal;
The opening degree command 20 (electric signal) is supplied with a current −
A proportional integrator 22 (PI controller) for outputting to the air converter 21 is provided.

The opening of the fuel control valve 3 can be changed by a positioner converter 24 supplied with pressurized air from a working air source 23, and an opening command 20 from the proportional integrator 22. Is converted into an air control signal 25 by the current-air converter 21, and the positioner converter 24 is operated by the air control signal 25 to control the opening of the fuel control valve 3. Although the case where the opening degree of the fuel control valve 3 is controlled by the air control signal 25 has been described above, there is a case where the opening degree of the fuel control valve 3 is directly controlled by the opening degree command 20 (electric signal). Yes,
In this case, the current-air converter 21 can be omitted.

According to the fuel control valve opening control device 14, the flow rate of the fuel 1 supplied to the boiler 4 is controlled by the fuel command 1
3 is automatically controlled.

The fuel regulating valve opening control device 14 is provided with an in-house isolated operation switching circuit 26 as shown in FIG.

The in-station independent operation switching circuit 26 includes a first switching device 27 provided between the proportional integrator 22 and the current-to-air converter 21 and, for example, three to three switches necessary for in-station in-station operation of the boiler 4. A signal generator 29 that outputs a specified opening 28 of about 5%, and a specified opening command 30 obtained by adding a rate of change (rate) to the specified opening 28 from the signal generator 29 to the first switch 27. And a second switch 32 provided between the signal generator 29 and the change rate limiter 31 to receive the opening degree command 20 from the proportional integrator 22. It has.

The first switch 27 and the second switch 32
Is switched to the b side during the normal operation of the boiler 4,
When the in-house isolated operation command 17 is issued, the operation is switched to the a side only for 60 seconds.

Further, the rate-of-change limiter 31 is connected to the first
Only when the switch 27 and the second switch 32 are respectively switched to the a side, the change rate (rate) is operated.

When the in-house isolated operation command 17 is issued, the proportional integrator 22 stops the control by the deviation signal 19 from the subtracter 18 and outputs the same signal as the signal at the exit of the first switch 27. A tie-back circuit 33 that switches to output a signal is provided.

Therefore, the fuel control valve opening control device 14
In the normal operation of the boiler 4, the proportional integrator 22
From the opening switch 20 through the first switch 27
Output to the air converter 21, the fuel control valve 3
Is controlled. At this time, the opening degree command 20 guided to the second switch 32 has reached the entrance of the first switch 27 via the change rate limiter 31.

In such a state, when an in-house isolated operation command 17 is issued due to an accident in the transmission system or an accident related to a substation, the first switch 27 and the second switch 27 of the in-house isolated operation switching circuit 26 are provided. 32 are switched to the a side only for 60 seconds, respectively, thereby, as shown in FIG. 6 and FIG.
The opening degree command 20 from the proportional integrator 22 that has been input to the switch 32 of the
% To 5%) and outputs it to the rate-of-change limiter 31, whereby the rate-of-change limiter 31 changes the required rate of change X (rate) from the opening command 20 to the specified opening 28.
Is output to the current-to-air converter 21 via the first switch 27. As a result, the fuel control valve 3 quickly moves to the specified opening degree 2.
The aperture is narrowed down to 8, and that state is maintained.

When the fuel control valve 3 is narrowed down to the specified opening degree 28 and 60 seconds have elapsed since the in-house isolated operation command 17 was issued, the first switch 27 and the second switch 32 are switched to the b side, respectively. However, at this time, the fuel command 1
3 is set to a low flow rate value corresponding to the specified opening degree 28 of the fuel control valve 3 at the time of the occurrence of the in-station independent operation, the proportional integrator 22 is set based on the fuel command 13 thus set small. The opening of the fuel control valve 3 is controlled via the first switch 27 and the current-to-air converter 21.

When the first switch 27 and the second switch 32 are switched to the a side by the in-house independent operation command 17, the proportional integrator 22 is switched to the first switch by the tie-back circuit 33.
The same signal as that of the switch 27 exit is output to the first switch 27. Therefore, when the first switch 27 is switched to the b side 60 seconds after the on-site islanding operation command 17 is issued. Switching can be performed stably.

The operation of narrowing down the fuel when the in-house isolated operation command 17 is issued needs to be performed at a rate of change X (rate) determined for protecting the reheater 11 in FIG. That is, when the in-house isolated operation command 17 is generated, the steam turbine 9,
Until now twelve loads have been cut off to 3000r
Since the rotation speeds of the steam turbines 9 and 12 which have been rotating at a rotation speed of 3 pm or 3600 rpm are rapidly increased, the rotation speed of the steam turbines 9 and 12 is reduced by temporarily narrowing the turbine control valve 8 once. The steam 6 taken into the steam turbines 9 and 12 rapidly becomes lean,
For this reason, there is a problem that the reheater 11 becomes steamed and burns.

For this reason, when the in-house single operation command 17 is issued, the fuel is narrowed down to the specified fuel α% or less in 10 seconds, and the fuel is narrowed down to the specified fuel β% or less in 30 seconds (the narrowing width when narrowing to α% or less) Is smaller than β% or less). Therefore, as shown in FIG. 7, the fuel control valve is controlled by the change rate limiter 31 of FIG. 6 at a predetermined change rate X (rate). 3 is performed in, for example, 30 seconds, and then settled in 30 seconds. Then, the first switch 27 and the second switch 32 are switched to the b side to perform control based on the fuel command 13. To do.

Therefore, if the operation of narrowing down the fuel control valve 3 is delayed when the in-house independent operation command 17 is issued, there is a problem that the reheater 11 cannot be protected, and the operation of narrowing down the fuel control valve 3 is too early. In this case, there is a problem that the pressure of the fuel 1 before the burner 5 decreases and the burner 5 is misfired. When the burner 5 is misfired, it takes a long time of 1 to 2 hours to restart the boiler 4, and therefore, even if an accident related to the power transmission system or the substation is restored, the power cannot be immediately restarted. is there.

[0021]

The rate of change X (rate) set in the rate-of-change limiter 31 provided in the conventional in-house isolated operation switching circuit 26 is set during an in-house isolated operation test performed when the boiler 4 is constructed. However, if the operation of the boiler 4 is continued, the opening degree deviation (drift) from the setting at the time due to abrasion of the burner chip and aging of the current-to-air converter 21 and the positioner converter 24 occurs. Due to the opening deviation, the fuel control valve 3 is not at the optimal opening during the in-house operation alone.
There is a danger that the in-house alone operation will fail due to burnout of the burner or misfire of the burner 5.

The present invention has been made in order to solve the problems of the conventional apparatus. When an in-house isolated operation occurs, the in-house independent operation can be performed by correcting the difference in the opening degree from the setting of the fuel control valve. It is an object of the present invention to provide a boiler fuel control valve opening control device having an in-house isolated operation function.

[0023]

According to the present invention, there is provided an in-house isolated operation switching circuit for switching an opening command output to a fuel control valve based on a fuel command to a specified opening when an in-station isolated operation command is issued. A differential pressure gauge for detecting a differential pressure between fuel on the inlet side and an output side of the fuel control valve, a calculator for calculating a square root of the differential pressure, a flow meter for detecting a fuel flow rate, and a proportional constant to the fuel flow rate , A divider that obtains a Cv value of the fuel control valve by dividing the flow coefficient signal by the square root of the differential pressure, and a mover that obtains a moving average value of the Cv value. An average calculator, a function generator that obtains a measurement valve opening signal from the moving average value of the Cv value, and a subtraction that obtains an opening deviation signal by subtracting the opening command and the measurement valve opening signal. Holds and outputs the opening deviation signal at the same time as the in-house isolated operation command is generated. Fuel control for a boiler provided with an in-house isolated operation function, comprising: a switching device that switches the opening degree from the switching device to a specified opening of the in-house isolated operation switching circuit. The present invention relates to a valve opening control device.

According to the present invention, the opening deviation signal is always obtained, and the opening deviation signal is held and added to the specified opening command simultaneously with the generation of the in-house independent operation command. And the aging of the current-to-air converter and the positioner converter, etc., the fuel control valve can be controlled by the specified opening command corrected by the opening deviation signal based on the aging. The operation of narrowing down the control valve is not delayed or prematurely performed, and the in-house isolated operation can be reliably performed at the optimal timing.

[0025]

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

FIG. 1 shows an example of an embodiment of the present invention. In the figure, portions denoted by the same reference numerals as those in FIG. 6 represent the same items.

As shown in FIG. 1, similarly to FIG. 6, the deviation signal 1 between the fuel command 13 and the fuel flow rate 16 from the flow meter 15 is shown.
The opening command 20 output from the proportional integrator 22 to the fuel control valve 3 via the current-to-air converter 21 is changed to the specified opening 28 by the in-house islanding operation command 17 so that 9 is eliminated.
In-house isolated operation switching circuit 2 that switches to and outputs
6 is provided.

On the other hand, the fuel control valve 3 in the fuel pipe 2
Pressure gauge 34 for detecting a differential pressure 35 between the fuel 1 on the inlet side and the fuel 1 on the outlet side.
Is provided. In the case of FIG. 1, pressure gauges 36 and 37 for detecting the pressure of the fuel 1 on the inlet side and the outlet side of the fuel control valve 3, and pressure detection signals 36 a and 37 a from the pressure gauges 36 and 37 are subtracted by a subtractor 38. , The differential pressure 35 is obtained.

The square root 3 of the differential pressure 35 from the differential pressure gauge 34
9 is provided. Further, a multiplier 43 for obtaining a flow coefficient signal 42 by multiplying the fuel flow 16 from the flow meter 15 by the proportionality constant 41 is provided, and the flow coefficient signal 42 from the multiplier 43 is calculated by the difference from the calculator 40. A divider 45 is provided for obtaining a Cv value 44 representing the characteristic of the fuel control valve 3 by dividing by the square root 39 of the pressure. Assuming that the fuel flow rate is Q, the constant is K, and the pressure detection signals 36a and 37a are P ₁ and P ₂ , the Cv value 44 of the fuel control valve 3 can be obtained from the following equation 1.

[0030]

(Equation 1)

The Cv value 44 is input to a moving average calculator 46, and as shown in FIG.
a is obtained, and a moving average value 46a of the Cv value 44 is input to a function generator 48 to which a reference value 47 is input.
9, a measurement valve opening signal 50 can be obtained.

An opening command 20 from the in-house isolated operation switching circuit 26 and a measurement valve opening signal 50 from the function generator 48 are input to a subtracter 51 and subtracted to open. A shift signal 52 is obtained. The opening degree deviation signal 52 is caused by the wear of the burner tip of the burner 5 of FIG. 1, the current-air converter 21 and the positioner converter 2.
The Cv value of the fuel control valve 3, which appears due to aging such as 4, has changed from the setting value.

Further, the opening shift signal 52 from the subtracter 51 is input to a dead zone addition function generator 54 having a dead zone 53 as shown in FIG. , And an opening deviation signal 52 from the dead zone addition function generator 54 is input to a switch 55.

The switch 55 is adapted to hold and output the opening deviation signal 52 from the dead zone addition function generator 54 at the same time as the generation of the in-house isolated operation command 17. The opening deviation signal 52 is added to the specified opening 28 from the signal generator 29 of the in-house isolated operation switching circuit 26 via an adder 56.

The operation of the embodiment shown in FIG. 1 will be described below.

During normal operation of the boiler 4, the proportional integrator 2
When the opening command 20 from the second 2 is output to the current-to-air converter 21 through the first switch 27, the opening of the fuel control valve 3 is automatically controlled.

At this time, the differential pressure gauge 34 detects the differential pressure 35 between the fuel 1 on the inlet side and the fuel 1 on the outlet side of the fuel control valve 3.
And the square root 39 obtained by the calculator 40 is input to the divider 45, and the flow coefficient signal 42 obtained by multiplying the fuel flow rate 16 from the flow meter 15 by the proportionality constant 41 by the multiplier 43 is obtained. Is input to the divider 45,
The Cv value 44 representing the characteristic of the fuel control valve 3 is obtained by dividing the flow coefficient signal 42 by the square root 39 of the differential pressure by the multiplier 43.

Further, the Cv value 44 is calculated by the moving average calculator 4
6, a moving average value 46a is obtained as shown in FIG. 2, and a moving average value 46a of the Cv value 44 is further input to a function generator 48, based on a reference value 47, as shown in FIG. A measurement valve opening signal 50 is obtained from the function 49.

The opening command 20 from the in-house isolated operation switching circuit 26 and the measurement valve opening signal 50 from the function generator 48 are input to a subtracter 51 and subtracted, whereby the opening is calculated. The shift signal 52 is obtained, and the opening shift signal 5
When 2 is input to the dead zone addition function generator 54, a dead zone 53 as shown in FIG. 4 is given.

The opening deviation signal 52 given the dead zone 53
Is input to a switch 55 which is configured to hold and output the opening deviation signal 52 from the dead zone addition function generator 54 at the same time as the generation of the in-house islanding operation command 17. The degree deviation signal 52 is added to the specified opening 28 from the signal generator 29 of the in-house isolated operation switching circuit 26 via an adder 56, so that the specified opening 28 is always corrected.

In the above state, when an in-house isolated operation command 17 is issued due to an accident in the power transmission system or an accident related to a substation, the first switch 27 of the in-house isolated operation switching circuit 26 is output.
And the second switch 32 is switched to the a side only for 60 seconds, whereby the opening command 20 from the proportional integrator 22 input to the second switch 32 is transmitted to the signal generator 29.
Is switched to the specified opening 28 (3% to 5%) and output to the rate-of-change limiter 31. As a result, the rate-of-change limiter 31 requires the specified opening 28 from the opening command 20. Is output to the current-to-air converter 21 via the first switch 27.

At this time, the opening deviation signal 52 from the dead zone addition function generator 54 is generated at the same time as the generation of the in-house isolated operation command 17.
Since the opening deviation signal 52 from the switch 55 for holding and outputting the signal is added to the specified opening 28 from the signal generator 29 of the in-house isolated operation switching circuit 26 via the adder 56, , Opening degree deviation signal 52 based on aging
Opening command 30 corrected by the first switch 2
7 and the current-to-air converter 21 to output the fuel to the fuel control valve 3. Therefore, even if the burner chip wears or the aging of the current-to-air converter 21 and the positioner converter 24 occurs, the fuel is output. The throttle operation of the control valve 3 is not delayed or prematurely performed, and the in-house isolated operation can be reliably performed at the optimal timing.

[0043]

According to the present invention, the opening deviation signal is always obtained, and the opening deviation signal is held and added to the specified opening command simultaneously with the generation of the in-house independent operation command. Even if the burner chip wears or the aging of the current-air converter and the positioner converter occurs, the fuel control valve can be controlled by the specified opening command corrected by the opening deviation signal based on the aging. Therefore, an excellent effect that the in-house isolated operation can be reliably performed at the optimal timing without delaying or prematurely narrowing down the fuel control valve can be obtained.

[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 diagram showing an example of calculating a moving average value from a Cv value.

FIG. 3 is a diagram showing an example of obtaining a measurement valve opening signal from a moving average value of Cv values.

FIG. 4 is a diagram illustrating an example of adding a dead zone to an opening degree shift signal.

FIG. 5 is a schematic diagram showing an example of a power generation boiler.

FIG. 6 is a block diagram showing an example of a conventional fuel control valve opening control device.

FIG. 7 is a diagram showing an example of an opening degree of a fuel control valve when an in-house islanding operation command is issued.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel 3 fuel control valve 13 fuel command 15 flow meter 16 fuel flow rate 17 in-house independent operation command 20 opening degree command 26 in-house independent operation switching circuit 28 specified opening 34 differential pressure gauge 35 differential pressure 39 square root 40 calculator 41 proportional constant 42 flow rate Coefficient signal 43 Multiplier 44 Cv value 45 Divider 46 Moving average calculator 46a Moving average value 48 Function generator 50 Measurement valve opening signal 51 Subtractor 52 Opening deviation signal 55 Switching unit 56 Adder

Claims (1)

[Claims] 1. An in-house isolated operation switching circuit for switching an opening command output to a fuel control valve based on a fuel command to a specified opening when an in-plant independent operation command is issued, and outputting the input signal to the fuel control valve. A differential pressure gauge for detecting the differential pressure between the fuel on the side and the output side, a calculator for calculating the square root of the differential pressure, a flow meter for detecting the fuel flow rate, and a flow coefficient signal obtained by multiplying the fuel flow rate by a proportional constant. A multiplier for obtaining the Cv value of the fuel control valve by dividing the flow coefficient signal by the square root of the differential pressure;
A moving average calculator for calculating the moving average value of the Cv value, a function generator for obtaining a measurement valve opening signal from the moving average value of the Cv value, and subtracting the opening command and the measurement valve opening signal A subtractor for obtaining an opening degree deviation signal, a switch for holding and outputting the opening degree deviation signal simultaneously with the generation of an in-house independent operation command, and an in-house operation for the opening degree deviation signal from the switch. An opening control device for a fuel control valve of a boiler having an in-house independent operation function, comprising: an adder for adding to a specified opening of a switching circuit.