JPH1089613A - Method and apparatus for controlling steam temperature upon ignition and extinguishing of burner in thermal power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress fluctuation in steam temperature of superheated steam caused by ignition or extinguishing of a burner and further keep steam temperature of the superheated steam at a predetermined set temperature. SOLUTION: A base bias instruction 36 for a flow rate of spray is calculated in response to the number N of ignited burners and in the case that the fundamental bias instruction 38 is varied, a processing for limiting its rate of variation within a range less than its set value is carried to attain a difference between the fundamental bias instruction 36 and the fundamental bias instruction 38 to produce a control bias instruction 40, wherein a fundamental preceding instruction 20 of spraying flow rate based on an output 18 of a power generator and the control bias instruction 40 are added to a spray flow rate control instruction 16 calculated in such a way that a steam temperature 10 of the superheated steam V may become a temperature set value 13 so as to attain a preceding control instruction 21 of the spray flow rate 23 and then the actual spray flow rate 23 is adjusted in response to the preceding control instruction 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a steam temperature at the time of extinguishing a burner point in a thermal power plant.

[0002]

2. Description of the Related Art Generally, a thermal power plant, as shown in FIG. 5, injects and burns fuel F from a large number of burners 2 into a furnace 1a of a boiler main body 1, and uses generated combustion gas G2. Water flowing through the heat transfer tubes of the boiler body 1;
The steam is heated and the main steam flowing in the superheater 5 disposed in the sub-side wall 1b of the boiler main body 1 is superheated, and the combustion gas G2 deprived of heat is discharged from the lower end of the rear heat transfer section 1c to the boiler exhaust gas. G3 is discharged to the exhaust gas duct 3 and the superheated steam V superheated by the superheater 5 is passed through the superheated steam pipe 6 to the steam turbine 7.
To drive the steam turbine 7 to drive the generator 8.

In the thermal power plant as described above, the steam temperature of the superheated steam V superheated by the superheater 5 and sent to the steam turbine 7 is sprayed into the main steam pipe 4 on the upstream side of the superheater 5. The adjustment is performed by supplying a desired amount of spray water from the water pipe 9. Therefore, the steam temperature 10 of the superheated steam V superheated by the superheater 5 is adjusted.
Is detected by the temperature detector 11, and the steam temperature 10 detected by the temperature detector 11 is input to the subtractor 12, and the steam temperature 10 and the temperature set value 13 are input to the subtractor 12.
And outputs the temperature deviation 14 to the proportional-integral controller 15, which outputs the temperature deviation 14.
Is output to the adder 17 while controlling the spray flow rate to eliminate the temperature deviation 14 by performing a proportional integration process.
Based on the generator output 18 of the generator 8, the function generator 19 determines a basic advance command 20 of the spray flow rate and calculates
7 and the adder 17 adds a spray flow control command 16 output from the proportional-integral controller 15 to a spray flow control basic command 20 output from the function generator 19. Preceding control command 21
And the difference between the preceding control command 21 and the actual spray flow rate 23 detected by the flow rate detector 22 is subtracted by a subtractor 24.
And outputs the spray flow rate deviation 25 to the proportional-integral controller 26. The proportional-integral controller 26 performs a proportional-integral process on the spray flow rate deviation 25 to precede the flow control valve 27 for eliminating the spray flow rate deviation 25. Control command 2
8 is output to the flow control valve 27, the opening of the flow control valve 27 is appropriately adjusted, and the steam temperature of the superheated steam V
Is set to the temperature set value 13.

Further, when the generator output 18 is changing and when the generator output 18 is in a predetermined area, a spray flow rate bias command 30 is issued from a function generator 29 based on the generator output 18. The bias command 30 is output as a command 32 to the adder 17 via the switch 31 switched to the a side in FIG. 5, and is output from the proportional-integral controller 15 in the adder 17. The bias command 30 (command 32) is added to the spray flow rate control command 16 and the spray flow rate basic advance command 20 output from the function generator 19. When the generator output 18 has not changed,
The switch 31 is switched to the b side in FIG. 5, and a signal 34 of “0” output from the signal generator 33 is a command 32.
Is output to the adder 17.

The function generator 19 is provided with a function F1 (x) as shown in FIG.
(X) indicates that the basic advance command 20 of the spray flow rate is increased or decreased substantially in proportion to the increase or decrease of the generator output 18, and the function generator 29 has the function shown in FIG. A function F2 (x) is set, and the function F2 (x) is set.
(X) indicates that the spray flow rate bias command 30 is set when the generator output 18 is in a predetermined area.

[0006]

However, in the thermal power plant as described above, when the burner 2 is ignited or extinguished from a certain number of burners to a certain number of burners, the steam temperature 10 fluctuates. Steam temperature fluctuations caused by fire extinguishing a
Since the bias command 30 does not coincide with the above, there is a case where the bias command 30 is not effective, and the bias command 30 originally does not enter where it is desired to increase the spray flow rate or enters where it does not want to increase the spray flow rate. Was happening.

The present invention has been made in view of the above circumstances, and it is possible to suppress the steam temperature fluctuation of superheated steam due to the burner point fire extinguishing and maintain the steam temperature of the superheated steam at a set temperature value at the time of burner point fire extinguishing in a thermal power plant. It is an object of the present invention to provide a method and apparatus for controlling a steam temperature.

[0008]

According to the present invention, a basic bias command for a spray flow rate supplied to a main steam pipe on the upstream side of a superheater is obtained based on the number of burner ignitions. A process for limiting the rate of change to a range equal to or less than a set value is performed to obtain a basic bias limit command, a difference between the basic bias command and the basic bias limit command is obtained as a control bias command, and a steam temperature of superheated steam is obtained. Is added to the spray flow rate control command obtained so that the temperature becomes the temperature set value, the spray flow rate basic advance command based on the generator output, and the control bias command to obtain a spray flow rate advance control command. The present invention relates to a method for controlling a steam temperature at the time of extinguishing a burner point in a thermal power plant, wherein an actual spray flow rate is adjusted based on a command. .

Further, the present invention provides a proportional-integral controller for outputting a control command of a spray flow rate into a main steam pipe on an upstream side of a superheater for eliminating a temperature deviation between a steam temperature sent from a boiler and a temperature set value. A function generator that calculates and outputs a basic advance command of the spray flow rate based on a generator output, a function generator that calculates and outputs a basic bias command of the spray flow rate based on the number of burners, and the basic bias command. Is changed, a change rate limiter that outputs a basic bias limit command by performing a process of limiting the change rate to a range equal to or less than a set value, and a difference between the basic bias command and the basic bias limit command is obtained. A subtractor that outputs a control bias command, and an adder that outputs a preceding control command for the spray flow rate by adding a basic preceding command and a control bias command to the control command, The difference between the preceding control command and the actual spray flow rate detected by the flow rate detector is determined, and a subtractor that outputs a spray flow rate deviation, and a preceding control command for eliminating the spray flow rate deviation, are provided in the middle of the spray water pipe. The present invention relates to a steam temperature control device at the time of extinguishing a burner point in a thermal power plant, comprising a proportional-integral regulator for outputting to a provided flow regulating valve.

According to the above means, the following effects can be obtained.

In the steam temperature control method for extinguishing a burner point in a thermal power plant according to the present invention, a basic bias command for a spray flow rate supplied to a main steam pipe upstream of a superheater is obtained based on the number of burners ignited. Along with
When the basic bias command is changed, a process of limiting the rate of change to a range equal to or less than a set value is performed to obtain a basic bias command, and a difference between the basic bias command and the basic bias command is obtained. A control bias command is added to the control command for the spray flow rate, which is determined so that the steam temperature of the superheated steam becomes the temperature set value, and a basic advance command for the spray flow rate based on the generator output and the control bias command are added. The advance control command of the spray flow rate is required,
The actual spray flow rate is adjusted based on the preceding control command.

Further, in the steam temperature control apparatus for extinguishing a burner point in a thermal power plant according to the present invention, the steam temperature detected by the temperature detector is input to a subtractor, and the steam temperature and the temperature setting are set in the subtractor. The difference from the value is obtained, the temperature deviation is output to the proportional-integral controller, and the temperature deviation is proportionally integrated in the proportional-integral controller, and a control command of the spray flow rate for eliminating the temperature deviation is sent to the adder. On the other hand, a basic advance command of the spray flow rate is obtained in the function generator based on the generator output and output to the adder, and further, a basic bias command of the spray flow rate is obtained in the function generator based on the number of burners. Output to the rate-of-change limiter and the subtractor, and when the basic bias command output from the function generator changes in the rate-of-change limiter, A process for limiting the rate of change to a range equal to or less than the set value is performed, and a basic bias limit command is output to the subtractor. In the subtractor, a basic bias command output from the function generator and output from the rate-of-change limiter are output. A difference from the basic bias limit command is obtained, a control bias command is output to the adder, and the function generator outputs a control command for the spray flow rate output from the proportional-integral controller in the adder. A basic advance command of the spray flow rate and a control bias command output from the subtractor are added,
A prior control command for the spray flow rate is obtained, a difference between the preceding control command and the actual spray flow rate detected by the flow rate detector is obtained in a subtractor, and a spray flow rate deviation is output to a proportional-integral controller, and the proportional In the integral controller, the spray flow rate deviation is proportionally integrated and a preceding control command for eliminating the spray flow rate deviation is output to the flow control valve, the opening of the flow control valve is appropriately adjusted, and the steam temperature of the superheated steam is adjusted. Is held at the temperature set value.

Here, when the number of burners is increased, the output of the function generator, that is, the basic bias command of the spray flow increases, but the output of the rate-of-change limiter, that is, the basic bias limiting command, Since the process of restricting the rate of change of the basic bias command output from the generator to a range equal to or less than the set value is performed, the basic bias command increases at a gentler gradient than the increasing gradient of the basic bias command. The output of the subtractor, that is, the control bias command is “0”
From the state described above, the burner ignition number increases at a predetermined slope from the time when it is increased, then gradually decreases at a gentler slope than at the time of increase, and returns to the state of “0” again.

Conversely, when the number of burners ignited decreases, the output of the function generator, ie, the basic bias command for the spray flow decreases, but the output of the rate-of-change limiter, ie, the basic bias limiting command, Since the process of limiting the rate of change of the basic bias command output from the function generator to a range equal to or less than a set value is performed, the basic bias command decreases at a gentler slope than the decreasing slope of the basic bias command. Thus, the output of the subtractor, that is, the control bias command is
From the state of “0”, the burner ignition number decreases at a predetermined slope from the time when the number of burners is reduced, then gradually increases at a gentler slope than at the time of the decrease, and returns to the state of “0” again.

If the number of burner ignitions is constant without increasing or decreasing, the basic bias command output from the function generator and the basic bias limit command output from the rate-of-change limiter become equal. The control bias command output from the device is maintained at "0".

As a result, the spray flow rate is appropriately increased or decreased with respect to the fluctuation of the steam temperature caused when the burner is ignited or extinguished from a certain number of burners to a certain number of burners, and the steam temperature of the superheated steam is surely increased. It is possible to maintain the temperature set value.

[0017]

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 FIG. 1, parts denoted by the same reference numerals as those in FIG. 5 represent the same parts, and reference numeral 35 denotes a spray flow rate based on the number N of burner ignitions. A function generator 37 for obtaining and outputting the basic bias command 36 performs processing for restricting the rate of change to a set value or less when the basic bias command 36 output from the function generator 35 changes. Basic bias limit command 3
A rate-of-change limiter 39 that outputs 8 calculates the difference between the basic bias command 36 output from the function generator 35 and the basic bias-limit command 38 output from the rate-of-change limiter 37,
A subtractor that outputs a control bias command 40; a spray command control 16 output from the proportional-integral controller 15 in the adder 17; a basic precedence command 20 for spray flow output from the function generator 19; A control flow command 40 output from the subtractor 39 is added to obtain a preceding control command 21 for the spray flow rate, and the difference between the preceding control command 21 and the actual spray flow rate 23 detected by the flow rate detector 22 is subtracted. The spray flow rate deviation 25 is output to a proportional-integral controller 26, and the proportional-integral controller 26 performs a proportional-integral process on the spray flow rate deviation 25, and a flow control valve 27 for eliminating the spray flow rate deviation 25. Of the superheated steam V by outputting the preceding control command 28 to the flow control valve 27 to adjust the opening of the flow control valve 27 appropriately. 10 is configured to be temperature setpoint 13.

The function generator 35 is provided with a function F3 (x) as shown in FIG.
(X) indicates that the basic bias command 36 of the spray flow rate is increased or decreased stepwise with respect to the increase or decrease of the number N of burner ignitions.

Next, the operation of the illustrated example will be described.

A steam temperature 10 of the superheated steam V superheated by the superheater 5 is detected by a temperature detector 11, and the steam temperature 10 detected by the temperature detector 11 is input to a subtractor 12, and the subtractor 12 The difference between the steam temperature 10 and the temperature set value 13 is determined, and a temperature deviation 14 is output to a proportional-integral controller 15. 1
A spray flow control command 16 for eliminating 4 is output to an adder 17, while a function flow generator 19 obtains a spray flow basic advance command 20 based on a generator output 18 of a generator 8. Further, the basic bias command 36 of the spray flow rate is obtained in the function generator 35 based on the number N of burner ignitions, and is output to the change rate limiter 37 and the subtractor 39. When the basic bias command 36 output from 35 changes, a process of restricting the rate of change to a range equal to or less than a set value is performed, and the basic bias restricting command 38
Is output to the subtractor 39, and the difference between the basic bias command 36 output from the function generator 35 and the basic bias limit command 38 output from the rate-of-change limiter 37 is calculated. 40 is output to the adder 17 where the proportional-integral controller 1
5 is added to the spray flow control command 16 output from the function generator 19 and the control bias command 40 output from the subtractor 39. Preceding control command 2
1 is obtained, the difference between the preceding control command 21 and the actual spray flow rate 23 detected by the flow rate detector 22 is obtained in a subtractor 24, and a spray flow rate deviation 25 is output to a proportional-integral controller 26. In the proportional integral controller 26, the spray flow rate deviation 25 is proportionally integrated, and a preceding control command 28 of the flow rate control valve 27 for eliminating the spray flow rate deviation 25 is output to the flow rate control valve 27. The opening is appropriately adjusted, and the steam temperature 10 of the superheated steam V is maintained at the temperature set value 13.

Here, for example, when the number N of burner ignitions increases from 5 to 6, as shown in FIG. 3, the output of the function generator 35, that is, the basic bias command 36 for the spray flow rate is changed from y to x. However, the output of the change rate limiter 37, that is, the basic bias limit command 38, is a process for limiting the change rate of the basic bias command 36 output from the function generator 35 to within a set value or less. From being
As a result, the output of the subtractor 39, that is, the control bias command 40, changes from a state of “0” to a value smaller than the slope of the increase of the basic bias command 36.
After the burner ignition number N increases at a predetermined slope from the time when it is increased, it gradually decreases at a gentler slope than when the burner ignition number N increases, and returns to the state of “0” again.

Conversely, the number N of burner ignitions is changed from six to five.
When the number is reduced to a book, as shown in FIG.
5, ie, the basic bias command 36 of the spray flow rate decreases from x to y, but the output of the rate-of-change limiter 37, ie, the basic bias command 38, is the basic bias command 36 output from the function generator 35. Of the basic bias command 36 is reduced at a gentler slope than the slope of the decrease of the basic bias command 36, whereby the output of the subtractor 39, that is, the control is performed. The bias command 40 decreases from the state of “0” at a predetermined slope from the point in time when the number N of burner ignitions is reduced, and then gradually increases at a gentler slope than at the time of the decrease. It returns to the form.

If the number N of burners is constant without increasing or decreasing, the basic bias command 36 output from the function generator 35 and the basic bias limit command 38 output from the rate-of-change limiter 37 are used. Since they are equal, the subtractor 39
Is maintained as "0".

As a result, the spray flow rate is appropriately increased or decreased with respect to the fluctuation of the steam temperature 10 caused when the burner 2 is ignited or extinguished from a certain number of burners to a certain number of burners, and the steam temperature of the superheated steam V is increased. 10 can be reliably maintained at the temperature set value 13.

Thus, the superheated steam V
Of the superheated steam V can be suppressed.
At the temperature setpoint 13.

The method and apparatus for controlling the steam temperature at the time of extinguishing a burner point in a thermal power plant according to the present invention are not limited to the above-described example, but may be variously modified without departing from the gist of the present invention. Can of course be added.

[0028]

As described above, according to the method and the apparatus for controlling the steam temperature at the time of extinguishing a burner point in a thermal power plant according to the present invention, it is possible to suppress the fluctuation of the steam temperature of the superheated steam due to the extinguishing of the burner point. An excellent effect of maintaining the steam temperature at the set temperature can be achieved.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a function F3 (x) set in a function generator 35 shown in FIG.

FIG. 3 shows a function generator 3 in a case where the number of burner ignitions is increased from 5 to 6 in an example of an embodiment of the present invention.
5 is a time chart illustrating outputs of a change rate limiter 37, a change rate limiter 37, and a subtractor 39.

FIG. 4 shows a function generator 3 in a case where the number of burner ignitions is reduced from 6 to 5 in an example of an embodiment of the present invention.
5 is a time chart illustrating outputs of a change rate limiter 37, a change rate limiter 37, and a subtractor 39.

FIG. 5 is a schematic configuration diagram of a conventional example.

6 is a diagram showing a function F1 (x) set in a function generator 19 shown in FIG.

7 is a diagram showing a function F2 (x) set in a function generator 29 shown in FIG.

[Explanation of symbols]

 2 Burner 4 Main steam pipe 5 Superheater 9 Spray water pipe 10 Steam temperature 11 Temperature detector 12 Subtractor 13 Temperature set value 14 Temperature deviation 15 Proportional integral controller 16 Control command 17 Adder 18 Generator output 19 Function generator 20 Basic Advance command 21 Advance control command 22 Flow rate detector 23 Spray flow rate 24 Subtractor 25 Spray flow rate deviation 26 Proportional integral controller 27 Flow rate regulating valve 28 Advance control command 35 Function generator 36 Basic bias command 37 Change rate limiter 38 Basic bias limit Command 39 Subtractor 40 Control bias command N Burner ignition number V Superheated steam

Claims (2)

[Claims] 1. A basic bias command for a spray flow rate supplied to a main steam pipe upstream of a superheater is obtained based on the number of burner ignitions, and when the basic bias command changes, the rate of change is set to a set value or less. A basic bias restriction command is obtained by performing a process of restricting the temperature within the range described above, a difference between the basic bias command and the basic bias restriction command is obtained as a control bias command, and the steam temperature of the superheated steam is set to a temperature set value. A basic control command for the spray flow rate based on the generator output is added to the control command for the spray flow rate thus obtained, and a control command for the spray flow rate is obtained by adding the control bias command. A steam temperature control method at the time of extinguishing a burner point in a thermal power plant. 2. A proportional-integral controller for outputting a control command of a spray flow rate into a main steam pipe on an upstream side of a superheater for eliminating a temperature difference between a steam temperature sent from a boiler and a temperature set value, and a generator. A function generator that obtains and outputs a basic advance command of the spray flow rate based on the output, a function generator that obtains and outputs a basic bias command of the spray flow rate based on the number of burners, and a case where the basic bias command changes. A rate-of-change limiter that performs a process of limiting the rate of change within a range equal to or less than a set value and outputs a basic bias limit command; and obtaining a difference between the basic bias command and the basic bias limit command, A subtractor for adding a basic advance command and a control bias command to the control command to output a preceding control command for the spray flow rate; Obtain the difference between the control command and the actual spray flow rate detected by the flow rate detector, a subtractor that outputs a spray flow rate deviation, and a preceding control command to eliminate the spray flow rate deviation,
A steam temperature control device for extinguishing a burner point in a thermal power plant, comprising a proportional-integral controller for outputting to a flow control valve provided in the middle of a spray water pipe.