WO2021029312A1

WO2021029312A1 - Control device for once-through boiler, power generation plant, and control method for once-through boiler

Info

Publication number: WO2021029312A1
Application number: PCT/JP2020/030137
Authority: WO
Inventors: 寿宏馬場; 和宏堂本; 尚三田
Original assignee: 三菱パワー株式会社
Priority date: 2019-08-14
Filing date: 2020-08-06
Publication date: 2021-02-18
Also published as: KR20220029703A; JP2021032420A; JP7465641B2

Abstract

The present disclosure relates to a control device for a once-through boiler, which can adjust the steam temperature from a furnace water cooling wall by a plurality of superheaters and a plurality of sprays. The control device performs control such that the temperature reduction amount of the steam by at least some of the plurality of sprays becomes a target temperature reduction amount. A bias value, which is set on the basis of the deviation between a detection value of the steam temperature and a target steam temperature on the upstream side of a spray position of the spray of which the temperature reduction amount in a steam flow path is controlled with respect to a basic target temperature reduction amount, is added to the target temperature reduction amount.

Description

Control device for once-through boiler, power plant, and control method for once-through boiler

The present disclosure relates to a once-through boiler control device, a power plant, and a once-through boiler control method.

Boiler devices that can generate steam are used in various applications, including power plants such as thermal power plants that generate electricity using steam energy. A once-through boiler is known as a method of this type of boiler device.

In Patent Document 1, as an example of a once-through boiler, a plurality of superheaters provided in series with respect to a flow path through which steam generated in a fireplace flows, and a plurality of sprays that can be sprayed on the outlet side of each superheater. A once-through boiler is disclosed. In the once-through boiler disclosed in Patent Document 1, steam is controlled by controlling the water-fuel ratio so that the steam temperature on the outlet side of the furnace and the outlet side of the superheater on the most downstream side becomes a predetermined set value (target steam temperature). It is configured so that the temperature can be adjusted.

Further, Patent Document 2 discloses a once-through boiler in which a final superheater (spray) is arranged between an upstream superheater group arranged in series on the downstream side of a steam generator and a final superheater. In the once-through boiler disclosed in Patent Document 2, the amount of water play by the final superheater is controlled so that the steam temperature on the outlet side of the final superheater becomes a predetermined set value (final target steam temperature), and the final superheater is used. It is configured to control the amount of fuel burned so that the temperature on the upstream side of the superheat reducer becomes a predetermined set value.

Japanese Patent No. 5840032 Japanese Patent No. 4453858

In the once-through boiler as in

Patent Documents

1 and 2, the final amount of temperature rise by each superheater, the amount of temperature decrease by each spray, and the amount of fuel supply for steam from the steam from the water cooling wall of the furnace are adjusted. It is desirable to perform various controls and adjustments so that the steam temperature profile becomes the target steam temperature and the steam temperature profile, which is the temperature distribution at each point of the steam flow path, becomes the ideal design temperature profile.

By the way, when operating a once-through boiler, the heat balance of the once-through boiler may change due to various factors, and the steam temperature profile may deviate from the design temperature profile. For example, if the heat transfer surface of the steam flow path becomes dirty with age, the detected value of the steam temperature in the steam flow path may decrease, or the superheat performance by the superheater may decrease. Further, by changing the type of fuel input to the furnace water cooling wall, heat transfer by the furnace water cooling wall or the superheater may increase. If the steam temperature profile deviates from the design profile in this way, the reliability and quality of the once-through boiler may be affected, such as affecting the pre-life of each member constituting the once-through boiler.

Some aspects of the present disclosure have been made in view of the above circumstances, and a once-through flow capable of suppressing deviation of the steam temperature profile balance from the design temperature profile as the heat balance conditions of the once-through boiler change. It is an object of the present invention to provide a boiler control device, a power plant, and a method for controlling a once-through boiler.

The once-through boiler control device according to some aspects of the present disclosure is used to solve the above problems.
The furnace water cooling wall and the plurality of superheaters are provided by a plurality of superheaters provided in series and a plurality of sprays configured so that a part of water supplied to the furnace water cooling wall can be sprayed on the outlet side of the plurality of superheaters. It is a control device for a once-through boiler that can adjust the temperature of steam generated by the superheater.
A spray control unit configured to be able to control the amount of heat reduction of the steam by at least a part of the plurality of sprays to be a target amount of heat reduction
Among the steam flow paths provided with the plurality of superheaters, a steam temperature detection unit configured to be able to detect the steam temperature on the upstream side of the spray position of the spray controlled by the spray control unit.
With
The target temperature reduction amount is configured to be set by adding a bias value set based on the deviation between the detection value of the steam temperature detection unit and the target steam temperature to the basic target temperature reduction amount. Will be done.

The power plant according to some aspects of the present disclosure is to solve the above problems.
With the once-through boiler,
Control devices according to some aspects of the present disclosure and
A turbine configured to be driveable using steam from the once-through boiler,
A generator configured to be driveable by the turbine,
To be equipped.

The method for controlling a once-through boiler according to some aspects of the present disclosure is to solve the above problems.
The furnace water cooling wall and the plurality of superheaters are provided by a plurality of superheaters provided in series and a plurality of sprays configured so that a part of water supplied to the furnace water cooling wall can be sprayed on the outlet side of the plurality of superheaters. It is a control method of a once-through boiler that can adjust the temperature of steam generated by the superheater.
A spray control step of controlling the amount of heat reduction of the steam by at least a part of the plurality of sprays so as to be a target amount of heat reduction.
A steam temperature detection step of detecting the steam temperature on the upstream side of the spray position of the spray controlled by the spray control unit among the steam flow paths provided with the plurality of superheaters.
With
The target temperature reduction amount is set by adding a bias value set based on the deviation between the detection value of the steam temperature detection unit and the target steam temperature to the basic target temperature reduction amount.

According to some aspects of the present disclosure, a once-through boiler controller, power plant, capable of suppressing deviation of the steam temperature profile balance from the design temperature profile as the heat balance conditions of the once-through boiler change. Also, a method for controlling a once-through boiler can be provided.

It is the schematic which shows the whole structure of the power plant which concerns on one aspect of this disclosure. It is a schematic block diagram which shows the structure of the once-through boiler of FIG. 1 together with a steam temperature profile. It is a block diagram which shows the internal structure of the control device which concerns on one aspect of this disclosure. It is a flowchart which shows the control method of the once-through boiler carried out by the control device of FIG. 3 for each process. This is an example showing the transition of the steam temperature profile by the control device of FIG. This is an example showing the transition of the steam temperature profile by the control device of FIG. This is an example showing the transition of the steam temperature profile by the control device of FIG. It is another example which shows the transition of the steam temperature profile by the control device of FIG. It is another example which shows the transition of the steam temperature profile by the control device of FIG. It is another example which shows the transition of the steam temperature profile by the control device of FIG. It is a block diagram which shows the internal structure of the control device which concerns on other aspects of this disclosure. It is a flowchart which shows the control method of the once-through boiler carried out by the control device of FIG. 7 for each process. This is an example showing the transition of the steam temperature profile by the control device of FIG. 7. This is an example showing the transition of the steam temperature profile by the control device of FIG. 7. This is an example showing the transition of the steam temperature profile by the control device of FIG. 7. It is another example which shows the transition of the steam temperature profile by the control device of FIG. It is another example which shows the transition of the steam temperature profile by the control device of FIG. It is another example which shows the transition of the steam temperature profile by the control device of FIG.

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention to that alone, but are merely explanatory examples.

<Power plant>
FIG. 1 is a schematic view showing an overall configuration of a power plant 100 according to one aspect of the present disclosure. The power plant 100 includes a once-through boiler 1 capable of generating steam, a turbine 110 configured to be driveable using steam from the once-through boiler 1, and a generator 120 configured to be driveable by the turbine 110. ..

The once-through boiler 1 is an example of a steam generator configured to be able to generate steam by burning fuel. The steam generated in the once-through boiler 1 is supplied to the turbine 110 via the steam supply path 112. The turbine 110 is driven by steam supplied through the steam supply path 112. A generator 120 is connected to the output shaft of the turbine 110, and the rotational energy of the turbine 110 is converted into electrical energy. The electric energy generated by the generator 120 is supplied to the electric power system (not shown) via a predetermined path.

A steam valve 114 (main steam valve) for adjusting the flow rate of steam supplied from the once-through boiler 1 to the turbine 110 is installed in the steam supply path 112. The opening degree of the steam valve 114 is controlled so that, for example, the steam flow rate supplied from the once-through boiler 1 to the turbine 110 becomes a predetermined target flow rate value set based on the load command value Ld for the power plant 100. ..

The power plant 100 has a control device 2 for controlling each component of the power plant 100. The control device 2 has a hardware configuration including an electronic arithmetic unit such as a computer, and by installing a program for implementing the control method according to some aspects of the present disclosure, the number of the present disclosure is increased. It is configured to be functional as a control device according to the above aspect.

The control device 2 is a control unit capable of comprehensively controlling the power plant 100. In the present specification, among various controls that can be performed by the control device 2, the control related to the once-through boiler 1 will be specifically described, and the other controls are publicly known regarding the power plant 100 unless otherwise specified. Can be controlled as appropriate.

The steam temperature control by the control device 2 is performed so that the steam temperature supplied to the turbine 110 (the third steam temperature T3SO described later) becomes a preset target steam temperature (the third target steam temperature T3SO target described later). .. This target steam temperature (third target steam temperature T3SOtaget described later) may be set manually by the operator, or may be automatically set based on a predetermined signal received by the control device 2. In the latter case, the target steam temperature (the third target steam temperature T3SOtaget described later) is, for example, according to the load command value Ld acquired by the power plant 100 according to the supply and demand state of the power system to which the power is supplied to the power plant 100. Set.

<Composition of once-through boiler>
Subsequently, a specific configuration of the once-through boiler 1 included in the power plant 100 having the above configuration will be described with reference to FIG. FIG. 2 is a schematic configuration diagram showing the configuration of the once-through boiler 1 of FIG. 1 together with a steam temperature profile.

The once-through boiler 1 has a furnace water cooling wall 4 (Water Wall) capable of generating steam. The furnace water cooling wall 4 has a heat transfer tube into which cooling water can be introduced, and heats the cooling water flowing through the heat transfer tube by burning fuel (for example, pulverized coal produced by crushing coal). Is configured to be able to generate steam. Water and fuel are supplied to the furnace water cooling wall 4 by, for example, a water supply pump unit or a fuel supply unit (not shown). The fuel flow rate to the reactor water cooling wall 4 is basically determined according to, for example, the load command value Ld for the power plant 100, but the fuel flow rate is determined according to the deviation between the actually generated steam temperature and the target steam temperature. The water-fuel ratio, which is a correction signal for correction, is controlled as one of the control parameters of the control device 2, as will be described later.

On the downstream side of the furnace water cooling wall 4, a plurality of superheaters 6 for superheating the steam generated by the furnace water cooling wall 4 are provided. The plurality of superheaters 6 are provided in series with each other with respect to the steam flow path 8 through which steam flows from the furnace water cooling wall 4. In the embodiment shown in FIG. 2, the plurality of superheaters 6 include a first superheater 6a, a second superheater 6b, and a third superheater 6c. By arranging the first superheater 6a on the downstream side of the furnace water cooling wall 4, the steam generated by the furnace water cooling wall 4 can be superheated. By arranging the second superheater 6b on the downstream side of the first superheater 6a, the steam superheated by the first superheater 6a can be further superheated. By arranging the third superheater 6c on the downstream side of the second superheater 6b, the steam superheated by the second superheater 6b can be further superheated.

Note that FIG. 2 illustrates a case where the once-through boiler 1 includes three superheaters 6, but the number of superheaters 6 provided by the once-through boiler 1 is not limited to this.

The steam flow path 8 is provided with a plurality of sprays 10 configured so that cooling water can be sprayed on the steam flowing through the steam flow path 8. In the aspect of FIG. 2, the plurality of sprays 10 are provided on the outlet side of the first superheater 6a (between the first superheater 6a and the second superheater 6b) in the steam flow path 8 of the first superheater 6a. And a second spray 10b provided on the outlet side of the second superheater 6b (between the second superheater 6b and the third superheater 6c). The first spray 10a adjusts the steam temperature by spraying cooling water on the steam from the first superheater 6a to reduce the temperature of the steam heated by the first superheater 6a. The second spray 10b adjusts the steam temperature by spraying cooling water on the steam from the second superheater 6b to reduce the temperature of the steam raised by the second superheater 6b.

The plurality of sprays 10 are configured so that a part of the water supply to the furnace water cooling wall 4 can be sprayed to the steam flow path 8. Specifically, the main water supply channel 12 for water supply to the fireplace water cooling wall 4 is provided with a sub water supply channel 14 that branches to the spray 10 side. The sub water supply channel 14 is configured to be able to supply water in parallel to each of the plurality of sprays 10. In this way, in the plurality of sprays 10, a part of the water supply supplied to the furnace water cooling wall 4 is sprayed. Therefore, when the spray amount in the spray 10 increases, the water supply amount to the furnace water cooling wall 4 decreases, and conversely, the spray. When the amount of spray at 10 decreases, the amount of water supplied to the furnace water cooling wall 4 increases.

The first spray 10a and the second spray 10b each have a first spray valve 16a and a second spray valve 16b that can be opened and closed to variably adjust the spray amount. The opening degree of the first spray valve 16a and the second spray valve 16b can be controlled independently of each other based on the control signal from the control device 2.

Note that FIG. 2 illustrates a case where the once-through boiler 1 includes two sprays 10, but the number of sprays 10 provided by the once-through boiler 1 is not limited to this. The number of sprays 10 may be set so as to be arranged on the outlet side of each of the superheaters 6 other than the superheater 6 on the most downstream side, for example.

The temperature of the steam generated in the furnace water cooling wall 4 is adjusted by the plurality of superheaters 6 and the plurality of sprays 10 so that the steam temperature supplied from the once-through boiler 1 to the turbine 110 becomes the target steam temperature. Be controlled. As shown in FIG. 2, the steam from the furnace water cooling wall 4 first passes through the first superheater 6a and is heated to the first steam temperature T1SO. The steam that has passed through the first superheater 6a is cooled by the first spray 10a on the outlet side of the first superheater 6a for the first heat reduction amount of 1 DSDT. Then, the steam cooled by the first spray 10a is heated to the second steam temperature T2SO by passing through the second superheater 6b. The steam that has passed through the second superheater 6b is cooled by the second spray 10b on the outlet side of the second superheater 6b for a second heat reduction amount of 2DSDT. Then, the steam cooled by the second spray 10b passes through the third superheater 6c and is heated to the third steam temperature T3SO, which is the final outlet temperature of the once-through boiler 1.

Such a steam temperature profile shown in FIG. 2 basically controls each component of the once-through boiler 1 (a furnace water cooling wall 4, a plurality of superheaters 6, and a plurality of sprays 10) by a control device 2. Is controlled so as to have an ideal design temperature profile Pr (in FIG. 2, the state in which the steam temperature profile matches the design temperature profile Pr is shown). Specifically, the control device 2 controls each component of the once-through boiler 1 so that the detection value of the temperature sensor provided at a predetermined measurement point of the once-through boiler 1 approaches the design temperature profile Pr, thereby steam. The temperature profile is managed to be the design temperature profile.

However, in the actual once-through boiler 1, the heat balance balance in the once-through boiler 1 may change due to various factors, and the steam temperature profile may deviate from the design temperature profile Pr. For example, if each heat transfer surface in the once-through boiler 1 becomes dirty such as scale with aging, the detection value of the temperature sensor provided at a predetermined measurement point of the once-through boiler 1 may decrease, or the first superheater may be used. The superheat performance by the 6a to 3rd superheater 6c may be deteriorated. Further, by changing the type of fuel charged into the furnace water cooling wall 4, the amount of heat transferred by the furnace water cooling wall 4 and the first superheater 6a to the third superheater 6c may increase or decrease. In some embodiments of the present disclosure, when the steam temperature profile deviates from the design temperature profile Pr in this way, the control device 2 causes the steam temperature profile to approach the design temperature profile Pr, as described below. The once-through boiler 1 is controlled.

The steam flow path 8 is configured so that the steam temperature at each position can be detected. Specifically, as shown in FIG. 2, the steam temperature T1SO on the outlet side of the first superheater 6a, the steam temperature 2T2SO on the outlet side of the second superheater 6b, and the steam temperature T3SO on the outlet side of the third superheater 6c. , The steam temperature T2SI after cooling by the first spray 10a and the steam temperature T3SI after cooling by the second spray 10b are each detectable. Each of these temperatures is detected by arranging a detection element such as a temperature sensor.

FIG. 3 is a block diagram showing an internal configuration of the control device 2 according to one aspect of the present disclosure, and FIG. 4 is a flowchart showing a control method of the once-through boiler 1 implemented by the control device 2 of FIG. 3 for each process. ..

As shown in FIG. 3, the control device 2 according to this embodiment controls the water fuel ratio control unit 50 for controlling the water fuel ratio of the furnace water cooling wall 4 and the spray 10 (first spray 10a and second spray 10b). A spray control unit 60 for calculating the bias value and a bias value calculation unit 70 for calculating a bias value with respect to the target temperature reduction amount of the spray 10 are provided. The spray control unit 60 includes a first spray control unit 60a for controlling the first spray 10a and a second spray control unit 60b for controlling the second spray 10b.

The water-fuel ratio control unit 50 controls the water-fuel ratio as a fuel flow correction so that the third steam temperature T3SO, which is the final steam temperature of the once-through boiler 1, becomes the preset third target steam temperature T3SO target. Specifically, the water-fuel ratio control unit 50 uses an actually measured value (for example, a steam temperature detected value on the downstream side of the third superheater 6c in the steam flow path 8) detected at a corresponding location of the once-through boiler 1. A certain third steam temperature T3SO and a preset third target steam temperature T3SO target are input. The water fuel ratio control unit 50 calculates the deviation ΔT3SO between the third steam temperature T3SO and the third target steam temperature T3SO target so that the deviation ΔT3SO becomes zero (that is, the third steam temperature T3SO is the third target steam temperature T3SO target). By outputting the water-fuel ratio control signal as fuel flow rate correction, the water-fuel ratio is feedback-controlled.

The third target steam temperature T3SOtaget may be set as the steam temperature value required for the once-through boiler 1 according to the load command value Ld.

The second spray control unit 60b controls the second spray 10b so that the third steam temperature T3SO becomes the third target steam temperature T3SO target and the second heat reduction amount 2DSDT becomes the second target heat reduction amount 2DSDT target. Specifically, in the second spray control unit 60b, the actually measured value detected at the corresponding portion of the once-through boiler 1 (for example, the steam temperature detected value on the downstream side of the third superheater 6c in the steam flow path 8). The third steam temperature T3SO, the preset third target steam temperature T3SO target, and the measured values (for example, the second superheater 6b and the third superheater 6c) detected by the sensor at the corresponding points of the once-through boiler 1. The second heat reduction amount 2DSDT, which is the difference between the steam temperature detection values detected on the upstream side and the downstream side of the spray position by the second spray 10b in the steam flow path 8 between them, and the preset second target. The amount of heat reduction 2DSDTtaget is input. In the second spray control unit 60b, the opening degree of the second spray valve 16b is such that the third steam temperature T3SO becomes the target steam temperature T3SO target and the temperature reduction amount 2DSDT by the second spray 10b becomes the target temperature reduction amount 2DSDT target. By outputting the command value (second spray valve opening signal), the second spray 10b is feedback-controlled.

The second temperature reduction target value 2DSDTtaget is set according to the load command value Ld.

The first spray control unit 60a outputs the opening command value (first spray valve opening signal) of the first spray valve 16a based on the temperature detection value T2S0 and the target temperature T2SOtaget, so that the first spray 10a Perform feedback control. That is, the first spray control unit 60a determines the opening signal of the first spray valve 16a so that the steam temperature on the outlet side of the second superheater 6b becomes a predetermined target value.

The bias value calculation unit 70 is a spray 10 whose temperature reduction amount is controlled by the spray control unit 60 among the steam flow paths 8 provided with the first superheater 6a to the third superheater 6c (in this embodiment, the second). The second target reduction is based on the deviation ΔT0 between the steam temperature T0 on the upstream side of the spray position of the second spray 10b) whose temperature reduction amount 2DSDT is controlled by the spray control unit 60b and the preset target steam temperature T0 target. The bias value α with respect to the temperature amount 2DSDT is calculated.
The bias value calculation unit 70 integrates and controls, for example, the deviation ΔT0, and calculates the output as the bias value α.

The steam temperature T0 is detected by the steam temperature detection unit 72 installed on the upstream side of the spray position of the second spray 10b whose temperature reduction amount 2DSDT is controlled by the second spray control unit 60b. In the embodiments shown in FIGS. 5A to 5C and 6A to 6C, as an example of the steam temperature detecting unit 72, the steam temperature T0 between the furnace water cooling wall 4 and the first superheater 6a in the steam flow path 8 is detected. It is configured to be possible.

The target steam temperature T0 target is set as the steam temperature T0 at the position corresponding to the steam temperature detection unit 72 according to the load command value Ld.

The control device 2 having such a configuration performs the control shown in FIG. First, the control device 2 detects the steam temperature at, for example, the outlet of the furnace water cooling wall 4 in the steam flow path 8 (step S100), and determines whether or not the steam temperature profile deviates from the design temperature profile Pr (step). S101).

When it is determined that the steam temperature profile deviates from the design temperature profile Pr (step S101: YES), the bias value calculation unit 70 determines the steam flow provided with the first superheater 6a to the third superheater 6c. The deviation ΔT0 between the steam temperature T0 on the upstream side of the spray position of the second spray 10b in the road 8 and the preset target steam temperature T0 target is calculated (step S102), and the bias value α is calculated based on the deviation T0. Calculate (step S103).

Here, the sign of the bias value α is set based on the magnitude relationship between the steam temperature T0 and the target steam temperature T0 target. Specifically, when the steam temperature T0 is lower than the target steam temperature T0 target, the sign of the bias value is set to positive. On the contrary, when the steam temperature T0 is higher than the target steam temperature T0 target, the sign of the bias value is set to negative. Further, the absolute value of the bias value is set so as to increase with respect to the deviation ΔT0.

Subsequently, the spray control unit 60 adds the bias value α set in step S103 to the second target heat reduction amount 2DSDTtaget (step S104), and the second heat reduction amount 2DSDT by the second spray 10b has a bias value α. The second spray 10b is controlled so as to have the added second target temperature reduction amount of 2DSDTtaget (step S105). By adding the bias value α to the target temperature reduction amount of the spray valve controlled so that the temperature reduction amount becomes the target temperature reduction amount in this way, the steam temperature profile of the once-through boiler 1 becomes the design temperature profile Pr. You can get closer.

Here, the transition of the steam temperature profile by the above control will be described more specifically. 5A to 5C are examples showing the transition of the steam temperature profile by the control device 2 of FIG. In this example, as shown in FIG. 5A, the steam temperature profile of the once-through boiler 1 deviates from the design temperature profile Pr to the lower temperature side for some reason. As such a factor, for example, the heat transfer surface of the steam flow path 8 becomes dirty such as scale with aging, the detected value of the steam temperature in the steam flow path 8 decreases, or the first superheater 6a to The superheat performance of the third superheater 6c has deteriorated, and the type of fuel charged into the steam furnace water cooling wall 4 has been changed.

In this case, since the steam temperature profile of the once-through boiler 1 deviates to the lower temperature side than the design temperature profile Pr, as shown in FIG. 5B, a bias value having a positive sign with respect to the second temperature reduction target value 2DSDTtaget. α is added. As a result, the amount of water supplied to the spray 10 side increases, and the amount of water supplied to the furnace water cooling wall 4 decreases. As a result, as shown in FIG. 5C, the steam temperature profile is generally shifted to the higher temperature side and controlled to approach the design temperature profile Pr.

6A to 6C are other examples showing the transition of the steam temperature profile by the control device 2 of FIG. In this example, as shown in FIG. 6A, the steam temperature profile of the once-through boiler 1 deviates from the design temperature profile Pr to the higher temperature side due to some factor. As such a factor, for example, the type of fuel charged into the furnace water cooling wall 4 has been changed.

In this case, since the steam temperature profile of the once-through boiler 1 deviates to the higher temperature side than the design temperature profile Pr, as shown in FIG. 6B, a bias value having a negative sign with respect to the second temperature reduction target value 2DSDTtaget. α is added. As a result, the amount of water supplied to the spray 10 side decreases, and the amount of water supplied to the furnace water cooling wall 4 increases. As a result, as shown in FIG. 6C, the steam temperature profile shifts to the low temperature side as a whole and approaches the design temperature profile Pr.

FIG. 7 is a block diagram showing an internal configuration of the control device 2 according to another aspect of the present disclosure. The control device 2 according to this aspect includes a water fuel ratio control unit 50 for controlling the water fuel ratio, a spray control unit 60 for controlling the spray 10 (first spray 10a and second spray 10b), and a target temperature reduction. A bias value calculation unit 70 for calculating a bias value with respect to the quantity is provided. The spray control unit 60 includes a first spray control unit 60a for controlling the first spray 10a and a second spray control unit 60b for controlling the second spray 10b.

The water-fuel ratio control unit 50 controls the water-fuel ratio so that the second steam temperature T2SO becomes the preset second target steam temperature T2SO target. Specifically, the water-fuel ratio control unit 50 has an actually measured value detected at a corresponding location of the once-through boiler 1 (for example, between the second superheater 6b and the third superheater 6c in the steam flow path 8). The second steam temperature T2SO, which is the steam temperature detection value), and the preset second target steam temperature T2SO target are input. The water fuel ratio control unit 50 calculates the deviation ΔT2SO between the second steam temperature T2SO and the second target steam temperature T2SO target so that the deviation ΔT2SO becomes zero (that is, the second steam temperature T2SO is the second target steam temperature T2SO target). By outputting the water-fuel ratio control signal as fuel flow rate correction, the water-fuel ratio is feedback-controlled.

The second target steam temperature T2SOtaget is set according to the load command value Ld.

The first spray control unit 60a controls the first spray 10a so that the second steam temperature T2SO becomes the second target steam temperature T2SO target and the first heat reduction amount 1DSDT becomes the first target heat reduction amount 1DSDTtaget. Specifically, in the first spray control unit 60a, an actually measured value detected at a corresponding location of the once-through boiler 1 (for example, between the second superheater 6b and the third superheater 6c in the steam flow path 8). The second steam temperature T2SO, which is the steam temperature detection value), the preset second target steam temperature T2SO target, and the measured values (for example, the first superheater 6a and the first superheater 6a) detected by the sensor at the corresponding points of the once-through boiler 1. 2 The difference between the steam temperature detection values detected on the upstream side and the downstream side of the spray position by the first spray 10a of the steam flow path 8 between the superheater 6b) and the first heat reduction amount 1DSDT in advance. The set first target heat reduction amount 1DSDTtaget and is input. The first spray control unit 60a has a first so that the second steam temperature T2SO becomes the second target steam temperature T2SO target and the first heat reduction amount 1DSDT by the first spray 10a becomes the first target heat reduction amount 1DSDT taget. The first spray 10a is feedback-controlled by outputting the opening command value (first spray valve opening signal) of the spray valve 16a.

The first target temperature reduction amount of 1DSDTtaget is set according to the load command value Ld.

The second spray control unit 60b outputs an opening command value (second spray valve opening signal) of the second spray valve 16b so that the third steam temperature T3SO becomes the third target steam temperature T3SO target. 2 Feedback control of the spray 10b is performed.

The bias value calculation unit 70 is a spray 10 (in this embodiment, the first) in which the amount of heat reduction is controlled by the spray control unit 60 among the steam flow paths 8 provided with the first superheater 6a to the third superheater 6c. The first is based on the deviation ΔT0 between the steam temperature T0 on the upstream side of the spray position of the first spray 10a) in which the first heat reduction amount 1DSDT is controlled by the spray control unit 60a and the preset target steam temperature T0 target. The bias value α with respect to the target temperature reduction amount 1DSDT is calculated.

The steam temperature T0 is detected by the steam temperature detection unit 72 installed on the upstream side of the spray position of the first spray 10a in which the first temperature reduction amount 1DSDT is controlled by the first spray control unit 60a. In the embodiment described later with reference to FIGS. 9A to 9C and FIGS. 10 to 10C, as an example of the steam temperature detection unit 72, steam between the furnace water cooling wall 4 and the first superheater 6a in the steam flow path 8 The temperature T0 is configured to be detectable.

The control device 2 having such a configuration performs the control shown in FIG. FIG. 8 is a flowchart showing a control method of the once-through boiler 1 implemented by the control device 2 of FIG. 7 for each process.

First, the control device 2 detects the steam temperature at, for example, the outlet of the furnace water cooling wall 4 in the steam flow path 8 (step S200), and determines whether or not the steam temperature profile deviates from the design temperature profile Pr (step S200). Step S201). When it is determined that the steam temperature profile deviates from the design temperature profile Pr (step S201: YES), the bias value calculation unit 70 determines the steam flow provided with the first superheater 6a to the third superheater 6c. The deviation ΔT0 between the steam temperature T0 on the upstream side of the spray position of the first spray 10a in the road 8 and the preset target steam temperature T0 target is calculated (step S202), and the bias value α is calculated based on the deviation T0. Calculate (step S203).

Subsequently, the spray control unit 60 adds the bias value α set in step S203 to the first target heat reduction amount 1DSDTtaget (step S204), and the first heat reduction amount 1DSDT by the first spray 10a has a bias value α. The first spray 10a is controlled so as to have the added first target temperature reduction amount of 1DSDTtaget (step S205). By adding the bias value α to the target temperature reduction amount of the spray valve controlled so that the temperature reduction amount becomes the target temperature reduction amount in this way, the steam temperature profile of the once-through boiler 1 becomes the design temperature profile Pr. You can get closer.

Here, the transition of the steam temperature profile by the above control will be described more specifically. 9A to 9C are examples showing the transition of the steam temperature profile by the control device 2 of FIG. 7. In this example, as shown in FIG. 9A, the steam temperature profile of the once-through boiler 1 deviates from the design temperature profile Pr to the lower temperature side for some reason. As such a factor, for example, the heat transfer surface of the steam flow path 8 becomes dirty such as scale with aging, the detected value of the steam temperature in the steam flow path 8 decreases, or the first superheater 6a to The superheat performance of the third superheater 6c has deteriorated, and the type of fuel charged into the steam furnace water cooling wall 4 has been changed.

In this case, since the steam temperature profile of the once-through boiler 1 deviates from the design temperature profile Pr to the lower temperature side, the bias value calculation unit 70 has an absolute value based on the deviation ΔT0 and has an absolute value as shown in FIG. 9B. The bias value α having a positive sign is calculated. As a result, as shown in FIG. 9C, the steam temperature profile shifts to the higher temperature side as a whole and approaches the design temperature profile Pr.

Further, FIGS. 10A to 10C are other examples showing the transition of the steam temperature profile by the control device 2 of FIG. 7. In this example, as shown in FIG. 10A, the steam temperature profile of the once-through boiler 1 deviates from the design temperature profile Pr to the higher temperature side for some reason. As such a factor, for example, the type of fuel charged into the furnace water cooling wall 4 has been changed.

In this case, since the steam temperature profile of the once-through boiler 1 deviates from the design temperature profile Pr to the higher temperature side, the bias value calculation unit 70 has an absolute value based on the deviation ΔT0 and has an absolute value as shown in FIG. 10B. The bias value α having a negative sign is calculated. As a result, as shown in FIG. 10C, the steam temperature profile shifts to the low temperature side as a whole and approaches the design temperature profile Pr.

As described above, according to some aspects of the present disclosure, the steam temperature profile at each position of the steam flow path of the once-through boiler 1 is derived from the design temperature profile as the heat balance condition of the once-through boiler 1 changes. It is possible to provide a control device 2 for a once-through boiler 1 capable of suppressing dissociation, a power plant 100, and a control method for the once-through boiler 1.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present disclosure, and the above-described embodiments may be combined as appropriate.

The contents described in each of the above embodiments are grasped as follows, for example.

(1) The once-through boiler control device according to one aspect of the present disclosure is
A plurality of superheaters provided in series (for example, the first superheater 6a, the second superheater 6b, and the third superheater 6c of the above embodiment) and a furnace water cooling wall (for example, the furnace water cooling wall 4 of the above embodiment). The furnace water cooling wall and the above are provided by a plurality of sprays (for example, the first spray 10a and the second spray 10b of the above embodiment) configured so that a part of the water supply to the superheater can be sprayed on the outlet side of the plurality of superheaters. A control device (for example, the control device 2 of the above embodiment) of a once-through boiler (for example, the once-through boiler 1 of the above embodiment) capable of adjusting the temperature of steam generated by a plurality of superheaters.
The amount of temperature reduction of the steam by at least a part of the plurality of sprays (for example, the first temperature reduction amount 1DSDT or the second temperature reduction amount 2DSDT of the above embodiment) is the target temperature reduction amount (for example, the first target reduction amount of the above embodiment). A spray control unit (for example, the spray control unit 60 of the above embodiment) configured to be controllable so as to have a temperature amount of 1DSDTtarget or a second target temperature reduction amount of 2DSDTtarget).
From the superheater arranged upstream of the spray position of the spray controlled by the spray control unit among the steam flow paths provided with the plurality of superheaters (for example, the steam flow path 8 of the above embodiment). A steam temperature detection unit (for example, the steam temperature detection unit 72 of the above embodiment) configured to be able to detect the steam temperature on the upstream side, and
With
The target temperature reduction amount is a bias value (for example, for example) set based on the deviation between the detection value of the steam temperature detection unit and the target steam temperature (for example, the deviation ΔT0 of the above embodiment) with respect to the basic target temperature reduction amount. It is configured to be set by adding the bias value α) of the above embodiment.

According to the aspect (1) above, the bias value is added to the target temperature reduction amount of the spray. The bias value is set based on the deviation of the steam temperature from the target steam temperature on the upstream side of the spray position of the spray whose temperature reduction amount is controlled to be the target temperature reduction amount. Thereby, even if the steam temperature profile in the steam flow path deviates from the ideal design temperature profile due to some factor, the steam temperature can be controlled so that the steam temperature profile approaches the design temperature profile.

(2) In another aspect, in the above aspect (1),
When the detection value of the steam temperature detection unit is lower than the target steam temperature, the sign of the bias value is set to be positive.

According to the aspect (2) above, when the steam temperature profile in the steam flow path deviates to the low temperature side with respect to the ideal design temperature profile, the sign of the bias value is set positively. This makes it possible to shift the steam temperature profile to the higher temperature side and bring it closer to the design temperature profile.

(3) In another aspect, in the above aspect (1) or (2),
When the detection value of the steam temperature detection unit is higher than the target steam temperature, the sign of the bias value is set to be negative.

According to the aspect (3) above, when the steam temperature profile in the steam flow path deviates from the ideal design temperature profile to the high temperature side, the sign of the bias value is set to negative. This makes it possible to shift the steam temperature profile to the lower temperature side and bring it closer to the design temperature profile.

(4) In another aspect, in any one of the above (1) to (3),
The absolute value of the bias value is set to increase with respect to the deviation.

According to the aspect (4) above, the bias value is set to increase as the amount of deviation between the steam temperature profile and the design temperature profile in the steam flow path increases. As a result, when the deviation amount of the steam temperature profile from the design temperature profile is large, the steam temperature profile can be suitably brought closer to the design temperature profile by adding a large bias value to the target temperature reduction amount.

(5) In another aspect, in any one of the above (1) to (4),
The plurality of superheaters
A first superheater (for example, the first superheater 6a of the above embodiment) configured to be able to superheat steam from the water cooling wall of the fireplace, and
A second superheater configured to superheat the steam from the first superheater (for example, the second superheater 6b of the above embodiment) and
A third superheater configured to superheat the steam from the second superheater (for example, the third superheater 6c of the above embodiment) and
Including
The plurality of sprays
A first spray provided on the outlet side of the first superheater (for example, the first spray 10a of the above embodiment) and
A second spray provided at the outlet of the second superheater (for example, the second spray 10b of the above embodiment) and
including.

According to the aspect (5) above, by controlling a plurality of superheaters and a plurality of sprays, the steam temperature profile from the furnace water cooling wall can be suitably brought close to the design temperature profile.

(6) In another aspect, in the above aspect (5),
The spray control unit has a deviation between the temperature reduction amount due to the second spray (for example, the second temperature reduction amount 2DSDT of the above embodiment) and the target temperature reduction amount (for example, the second target temperature reduction amount 2DSDT target of the above embodiment). Based on the above, the second spray is configured to be controllable.

According to the aspect (6) above, in the once-through boiler in which the second spray is controlled so that the temperature reduction amount by the second spray becomes the target temperature reduction amount, the steam temperature profile from the furnace water cooling wall is used as the design temperature profile. It can be brought closer to suitability.

(7) In another aspect, in the above aspect (5),
In the spray control unit, the temperature reduction amount by the first spray (for example, the first heat reduction amount 1DSDT of the above embodiment) becomes the target temperature reduction amount (for example, the first target temperature reduction amount 1DSDT target of the above embodiment). In addition, the first spray is configured to be controllable.

According to the aspect (7) above, in the once-through boiler in which the first spray is controlled so that the temperature reduction amount by the first spray becomes the target temperature reduction amount, the steam temperature profile from the furnace water cooling wall is used as the design temperature profile. It can be brought closer to suitability.

(8) In another aspect, in any one of the above (1) to (7),
The temperature reduction amount is calculated based on the temperature detection values on the upstream side and the downstream side of the spray, which is the control target of the spray control unit.

According to the aspect (8) above, the amount of temperature decrease due to the spray is suitably calculated based on the temperature detection values on the upstream side and the downstream side of the spray.

(9) In another aspect, in any one of the above (1) to (8),
The once-through boiler is a coal-fired boiler that uses coal or oil as fuel.

According to the above aspect (9), a coal-fired boiler or an oil-fired boiler, which has a low response to a load command value by operation control due to a process of crushing coal with a pulverized coal mill, is used as a steam generator. Also in a power plant, the steam temperature profile from the boiler water cooling wall can be suitably close to the design temperature profile.

(10) The power plant according to one aspect of the present disclosure is
With the once-through boiler,
The control device according to any one of (1) to (9) above,
A turbine configured to be driveable using steam from the once-through boiler,
A generator configured to be driveable by the turbine,
To be equipped.

According to the above aspect (10), even when the steam temperature profile of the once-through boiler deviates from the design temperature profile, the steam temperature profile is brought closer to the design temperature profile to make the power plant more stable. It can be operated and good reliability can be obtained.

(11) The method for controlling a once-through boiler according to one aspect of the present disclosure is as follows.
The furnace water cooling wall and the plurality of superheaters are provided by a plurality of superheaters provided in series and a plurality of sprays configured so that a part of water supplied to the furnace water cooling wall can be sprayed on the outlet side of the plurality of superheaters. It is a control method of a once-through boiler that can adjust the temperature of steam generated by the superheater.
A spray control step of controlling the amount of heat reduction of the steam by at least a part of the plurality of sprays so as to be a target amount of heat reduction.
Steam temperature detection that detects the steam temperature on the upstream side of the superheater located upstream of the spray position of the spray controlled by the spray control unit among the steam flow paths provided with the plurality of superheaters. Process and
With
The target temperature reduction amount is set by adding a bias value set based on the deviation between the detection value of the steam temperature detection unit and the target steam temperature to the basic target temperature reduction amount.

According to the aspect (11) above, the bias value is added to the target temperature reduction amount of the spray. The bias value is set based on the deviation of the steam temperature from the target steam temperature on the upstream side of the spray position of the spray whose temperature reduction amount is controlled to be the target temperature reduction amount. Thereby, even if the steam temperature profile in the steam flow path deviates from the ideal design temperature profile due to some factor, the steam temperature can be controlled so that the steam temperature profile approaches the design temperature profile.

1 once-through boiler 2 controller 4 furnace water cooling wall 6 superheater 6a 1st superheater 6b 2nd superheater 6c 3rd superheater 8 steam flow path 10 spray 10a 1st spray 10b 2nd spray 12 main water supply channel 14 sub water supply channel 16a 1st spray valve 16b 2nd spray valve 50 Superheater ratio control unit 60 Spray control unit 60a 1st spray control unit 60b 2nd spray control unit 70 Boil value calculation unit 72 Steam temperature detection unit 100 Power plant 110 Turbine 112 Steam supply path 114 steam valve 120 generator

Claims

The furnace water cooling wall and the plurality of superheaters are provided by a plurality of superheaters provided in series and a plurality of sprays configured so that a part of water supplied to the furnace water cooling wall can be sprayed on the outlet side of the plurality of superheaters. It is a control device for a once-through boiler that can adjust the temperature of steam generated by the superheater.
A spray control unit configured to be controllable so that the amount of heat reduction of the steam by at least a part of the plurality of sprays becomes the target amount of heat reduction.
Of the steam flow paths provided with the plurality of superheaters, the steam temperature on the upstream side of the superheater arranged upstream of the spray position of the spray controlled by the spray control unit can be detected. Steam temperature detector and
With
The target temperature reduction amount is configured to be set by adding a bias value set based on the deviation between the detection value of the steam temperature detection unit and the target steam temperature to the basic target temperature reduction amount. Control device for once-through boiler.
The control device for a once-through boiler according to claim 1, wherein when the detection value of the steam temperature detection unit is lower than the target steam temperature, the sign of the bias value is set to be positive.
The control device for a once-through boiler according to claim 1 or 2, wherein when the detection value of the steam temperature detection unit is higher than the target steam temperature, the sign of the bias value is set to negative.
The control device for a once-through boiler according to any one of claims 1 to 3, wherein the absolute value of the bias value is set to increase with respect to the deviation.
The plurality of superheaters
A first superheater configured to superheat steam from the fireplace water cooling wall, and
A second superheater configured to superheat the steam from the first superheater, and
A third superheater configured to superheat the steam from the second superheater, and
Including
The plurality of sprays
The first spray provided on the outlet side of the first superheater and
A second spray provided at the outlet of the second superheater and
The control device for a once-through boiler according to any one of claims 1 to 4, which comprises.
The control device for a once-through boiler according to claim 5, wherein the spray control unit is configured to be able to control the second spray based on a deviation between the temperature reduction amount due to the second spray and the target temperature reduction amount. ..
The control device for a once-through boiler according to claim 5, wherein the spray control unit is configured to be able to control the first spray so that the amount of heat reduction by the first spray becomes the target amount of heat reduction.
The control of the once-through boiler according to any one of claims 1 to 7, wherein the temperature reduction amount is calculated based on temperature detection values on the upstream side and the downstream side of the spray to be controlled by the spray control unit. apparatus.
The control device for a once-through boiler according to any one of claims 1 to 8, wherein the once-through boiler is a coal-fired boiler that uses coal or oil as fuel.
With the once-through boiler,
The control device according to any one of claims 1 to 9.
A turbine configured to be driveable using steam from the once-through boiler,
A generator configured to be driveable by the turbine,
A power plant equipped with.
The furnace water cooling wall and the plurality of superheaters are provided by a plurality of superheaters provided in series and a plurality of sprays configured so that a part of water supplied to the furnace water cooling wall can be sprayed on the outlet side of the plurality of superheaters. It is a control method of a once-through boiler that can adjust the temperature of steam generated by the superheater.
A spray control step of controlling the amount of heat reduction of the steam by at least a part of the plurality of sprays so as to be a target amount of heat reduction.
Steam temperature detection that detects the steam temperature on the upstream side of the superheater located upstream of the spray position of the spray controlled by the spray control unit among the steam flow paths provided with the plurality of superheaters. Process and
With
The target temperature reduction amount is set by adding a bias value set based on the deviation between the detection value of the steam temperature detection unit and the target steam temperature to the basic target temperature reduction amount. Control method.