JP7261113B2 - BOILER CONTROL DEVICE, BOILER SYSTEM, POWER PLANT, AND BOILER CONTROL METHOD - Google Patents

Description

The present disclosure relates to a boiler control device, a boiler system, a power plant, and a boiler control method.

2. Description of the Related Art A power plant is known in which a heat medium is heated by condensed heat of sunlight (solar heat), and the heat medium is used for heating feed water of a boiler. Such a power plant has the advantage of reducing boiler fuel consumption and carbon dioxide emissions. However, in such a configuration, the amount of heat received by the heat medium from the solar heat fluctuates due to changes in the amount of solar radiation, and the temperature of the boiler feed water fluctuates. In a power plant, it is necessary to suppress the influence of such fluctuations in the temperature of feed water in order to ensure the longevity of components and the stability of steam generated from boilers.

Patent Document 1 is a combination of solar heat and fuel boiler, which includes a boiler that heats feed water with combustion gas, and a CSP device that heats feed water with solar heat (CSP: Concentrating Solar Power) to generate CSP steam. It discloses a power generation system. In this system, CSP steam is branched and supplied to the inlet and outlet of the boiler, and the inlet steam temperature (main steam temperature) of the steam turbine is adjusted by adjusting the ratio of those supplies. Also, this system adjusts the main steam temperature by controlling the rate of CSP steam supply according to the solar radiation intensity and the CSP steam temperature.

JP 2016-160775 A

In the configuration disclosed in Patent Document 1, the rate of supply of CSP steam is controlled when the amount of heat received from solar heat fluctuates. However, such control does not control the flow rate of fuel supplied to the boiler in response to fluctuations in the amount of heat received from the sun.

Note that Patent Literature 1 suggests controlling the fuel flow rate based on the main steam temperature. According to such a configuration, when the main steam temperature fluctuates due to fluctuations in the amount of heat received from the sun, the fuel flow rate is controlled to increase or decrease the fuel flow rate supplied to the boiler.

However, since there is a time lag between when the amount of heat received from the sun fluctuates and when the temperature of the main steam fluctuates, it is not possible to properly There is a possibility that the fuel flow rate cannot be controlled. For example, even if the amount of heat received from the solar heat suddenly increases, the control for reducing the fuel flow rate may be delayed and the fuel consumption of the boiler may not be sufficiently reduced.

In addition, even if the main steam temperature can be adjusted within the allowable range, there is a possibility that the steam temperature or the feedwater temperature in the upstream heat exchanger is not adjusted within the allowable range of the heat exchanger specifications. . That is, there is a possibility that the temperature distribution in the boiler cannot be sufficiently optimized in the configuration in which the fuel flow rate supplied to the boiler is controlled based on the main steam temperature.

In view of the above circumstances, the present disclosure provides a boiler control device and the like that can more appropriately control the flow rate of fuel supplied to the boiler in response to the amount of heat received from the outside, such as solar heat, that fluctuates. With the goal.

The boiler control device according to the present disclosure includes:
A control device for a boiler that generates steam from feed water,
A first control signal for acquiring a first control signal for generating a fuel flow rate of fuel to be supplied to the boiler based on a base fuel flow rate signal generated based on the output target command and a third control signal according to the boiler load condition an acquisition unit;
a received heat amount information acquisition unit configured to acquire received heat amount information related to a fluctuating received heat amount from the outside;
a correction signal acquisition unit configured to convert the received heat amount indicated by the received heat amount information acquired by the received heat amount information acquisition unit into the fuel flow rate and acquire a correction signal for correcting the first control signal; ,
a fuel flow rate command unit configured to output a fuel flow rate command for controlling the fuel flow rate based on the first control signal and the correction signal to which a delay element is added;
Prepare.

The boiler system according to the present disclosure is
a control device for the boiler;
a heat medium circulation channel for circulating a heat medium that receives fluctuating heat from the outside;
a boiler that includes an economizer, a primary superheater and a secondary superheater, and generates steam by heating feed water that has undergone heat exchange with the heat medium by combustion of fuel;
Prepare.

A power plant according to the present disclosure includes:
the above boiler system;
a steam turbine rotationally driven by the steam generated by the boiler system;
a generator connected to the steam turbine for generating power according to rotation of the steam turbine;
Prepare.

A boiler control method according to the present disclosure includes:
A control method for a boiler that generates steam from feed water, comprising:
A step of acquiring a first control signal for generating a fuel flow rate of fuel supplied to the boiler based on a base fuel flow rate signal generated based on the output target command and a third control signal according to the boiler load condition;
a step of acquiring heat-receiving amount information about the amount of heat received that varies from the outside;
a step of converting the received heat amount indicated by the acquired received heat amount information into the fuel flow rate and acquiring a correction signal for correcting the first control signal;
outputting a fuel flow rate command for controlling the fuel flow rate based on the first control signal and the correction signal to which a delay element is added;
Prepare.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a boiler control device and the like that can more appropriately control the flow rate of fuel supplied to the boiler in response to the amount of heat received from the outside, such as solar heat, that fluctuates.

1 is a schematic configuration diagram of a boiler system according to one embodiment; FIG. 1 is a schematic configuration diagram of a power plant according to one embodiment; FIG. FIG. 2 is a block diagram showing the configuration of the boiler control device relating to fuel flow rate control according to one embodiment. FIG. 5 is a conceptual diagram for explaining temperature distribution in a boiler according to a comparative example; FIG. 4 is a diagram for explaining the correction of the third control signal of the boiler control device according to the embodiment, and is a conceptual diagram showing the temporal transition of the steam temperature of the boiler. FIG. 4 is a diagram for explaining the correction of the third control signal of the boiler control device according to the embodiment, and is a conceptual diagram showing the temporal transition of the fuel flow rate supplied to the boiler. FIG. 3 is a block diagram showing a configuration related to damper opening degree control of the boiler control device according to the embodiment. FIG. 4 is a diagram for explaining opening degree control of a damper of a control device for a boiler according to one embodiment, and is a conceptual diagram showing a temporal transition of outlet feed water temperature of an economizer. 4 is a flowchart showing an example of control processing executed by the boiler control device according to the embodiment;

Several embodiments will now be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the invention, but are merely illustrative examples. .
For example, expressions denoting relative or absolute arrangements such as "in a direction", "along a direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" are strictly not only represents such an arrangement, but also represents a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which express that things are in the same state, not only express the state of being strictly equal, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, expressions that express shapes such as squares and cylinders do not only represent shapes such as squares and cylinders in a geometrically strict sense, but also include irregularities and chamfers to the extent that the same effect can be obtained. The shape including the part etc. shall also be represented.
On the other hand, the expressions "comprising", "comprising", "having", "including", or "having" one component are not exclusive expressions excluding the presence of other components.

(Schematic configuration of boiler system)
A schematic configuration of the boiler system 1 according to one embodiment will be described below. In this embodiment, as an example of receiving fluctuating heat from the outside, a boiler system 1 that receives solar heat from condensed sunlight will be described. FIG. 1 is a schematic configuration diagram of a boiler system 1 according to one embodiment. This figure shows the combustion gas system of the boiler system 1, and does not include the water supply system, the steam system, the circulation flow path of the heat medium that receives the solar heat, and the like. These configurations will be described later.

As shown in FIG. 1 , the boiler system 1 includes a coal-fired boiler (boiler) 10 that generates steam, and a boiler control device 100 that controls the boiler 10 . The boiler 10 of the present embodiment uses pulverized coal obtained by pulverizing coal (carbon-containing solid fuel) as pulverized fuel, and burns this pulverized fuel with combustion burners 21, 22, 23, 24, 25. ) boiler 10 . The boiler 10 of the present embodiment recovers heat generated by combustion and exchanges heat with feed water or steam to generate superheated steam. In the following description, "up" and "up" indicate the upper side in the vertical direction, and "down" and "lower side" indicate the lower side in the vertical direction.

The boiler 10 has a furnace 11 , a combustion device 12 and a flue 13 . The furnace 11 has a hollow rectangular shape and is installed along the vertical direction. The furnace wall (heat transfer tube) that constitutes the furnace 11 is composed of a plurality of evaporating tubes and fins that connect them. suppressing the rise.

The combustion device 12 is provided on the lower side of the furnace wall that constitutes the furnace 11 . In this embodiment, the combustion device 12 comprises a plurality of combustion burners (eg combustion burners 21, 22, 23, 24, 25) mounted on the furnace wall. For example, the combustion burners 21 , 22 , 23 , 24 , 25 are arranged along the circumferential direction of the furnace 11 at regular intervals as one set, and arranged in a plurality of stages along the vertical direction. However, the shape of the furnace 11, the number of combustion burners in one stage, and the number of stages are not limited to this embodiment.

Each combustion burner 21, 22, 23, 24, 25 is connected to a plurality of pulverizers (mills) 31, 32, 33, 34, 35 via pulverized coal supply pipes 26, 27, 28, 29, 30. there is Although not shown, the crushers 31, 32, 33, 34, and 35 have, for example, a housing in which a rotary table is supported so as to be driven and rotatable. It is configured to be rotatably supported. When the coal is fed between a plurality of rollers and the rotary table, it is pulverized to a predetermined pulverized coal size and transported to a classifier (not shown) by a carrier gas (primary air, oxidizing gas). Pulverized fuel classified within a predetermined size can be supplied to combustion burners 21 , 22 , 23 , 24 and 25 from pulverized coal supply pipes 26 , 27 , 28 , 29 and 30 .

Further, the furnace 11 is provided with wind boxes 36 at the mounting positions of the combustion burners 21, 22, 23, 24 and 25. As shown in FIG. One end of an air duct 37 is connected to the wind box 36 . A forced draft fan (FDF) 38 is provided at the other end of the air duct 37 .

The flue 13 is connected to the upper part of the furnace 11 in the vertical direction. The flue 13 includes a primary superheater 43, a secondary superheater 42, a tertiary superheater 41, reheaters 44, 45, and economizers 46, 47 as heat exchangers for recovering the heat of the combustion gas. Heat is exchanged between combustion gas generated by combustion in the furnace 11 and water or steam flowing through each heat exchanger.

A gas duct 48 is connected to the downstream side of the flue 13 through which combustion gas that has undergone heat exchange is discharged as exhaust gas. An air heater (air preheater) 49 is provided between the gas duct 48 and the air duct 37, and heat exchange is performed between the air flowing through the air duct 37 and the exhaust gas flowing through the gas duct 48, and the combustion burners 21, 22, . The combustion air supplied to 23, 24, 25 can be heated.

A denitrification device 50 is provided in the flue 13 upstream of the air heater 49 . The denitrification device 50 supplies a reducing agent such as ammonia or urea water, which has an action of reducing nitrogen oxides, into the flue 13, and causes the reaction between the nitrogen oxides and the reducing agent in the combustion gas to which the reducing agent is supplied. Promote. This removes or reduces nitrogen oxides in the combustion gas. A gas duct 48 connected to the flue 13 is provided with a dust processing device (electric dust collector, desulfurization device) 51, an induced draft fan (IDF) 52, etc. at a position downstream of the air heater 49. A chimney 53 is provided at the end.

On the other hand, when the plurality of pulverizers 31, 32, 33, 34, 35 are driven, the pulverized fuel produced is fed to the combustion burners 21, 22, 23 through the pulverized coal supply pipes 26, 27, 28, 29, 30 together with the carrier gas. , 24, 25. Also, by exchanging heat with the exhaust gas discharged from the boiler 10 by the air heater 49, the heated combustion air (oxidizing gas) flows from the air duct 37 through the wind box 36 to the combustion burners 21, 22, 23, 24, 25. Then, the combustion burners 21, 22, 23, 24, and 25 blow into the furnace 11 a pulverized fuel mixture in which pulverized fuel and a carrier gas (primary air, oxidizing gas) are mixed, and blow combustion air into the furnace 11. A flame can be formed by blowing in and igniting at this time. A flame is generated in the lower part of the furnace 11 , combustion gas rises in the furnace 11 and is discharged to the flue 13 .

Air is used as the oxidizing gas in this embodiment. The oxidizing gas may contain more or less oxygen than air, and can be used by optimizing the fuel flow rate.

After that, the combustion gas is heat-exchanged by the primary superheater 43, the secondary superheater 42, the tertiary superheater 41, the reheaters 44, 45, and the economizers 46, 47 arranged in the flue 13, and then Nitrogen oxides are reduced and removed by 50 to become exhaust gas, and after particulate matter and sulfur content are removed by a dust treatment device 51, the exhaust gas is discharged from a chimney 53 into the atmosphere.

A bypass passage 55 that bypasses the economizers 46 and 47 is provided in the flue 13 . A damper 56 is provided in the bypass flow path 55 . The opening of the damper 56 is controlled by a boiler control device 100 . Part of the combustion gas in the flue 13 bypasses the economizers 46 and 47 and goes to the denitrification device 50 according to the opening of the damper 56 . The boiler control device 100 controls not only the opening degree of the damper 56 but also the fuel flow rate supplied to the boiler 10 . For example, the boiler control device 100 controls the flow rate of coal supplied to the plurality of pulverizers 31, 32, 33, 34, 35 by a coal supply device (not shown), and controls the combustion burners 21, 22, 23, 24, Controls the flow rate of pulverized fuel supplied to 25. Note that the method of controlling the fuel flow rate is not limited to this example.

Next, as one embodiment, the primary superheater 43, the secondary superheater 42, the tertiary superheater 41, the reheaters 44, 45, and the economizers 46, 47 provided in the flue 13 as heat exchangers. I will explain in detail. FIG. 2 is a schematic configuration diagram of the power plant 2 according to one embodiment. FIG. 2 schematically shows the heat exchangers of the boiler 10 and the steam and feedwater systems. In addition, FIG. 2 shows the position of each heat exchanger (primary superheater 43, secondary superheater 42, tertiary superheater 41, reheaters 44, 45, economizers 46, 47) in the flue 13. is not what is shown in

As shown in FIG. 2 , the power plant 2 includes a boiler system 1 , a steam turbine 61 rotationally driven by steam generated by the boiler system 1 , and connected to the steam turbine 61 to generate power according to the rotation of the steam turbine 61 . and a generator 3 that performs The boiler system 1 further includes a heat medium circulation flow path L6 for circulating the heat medium. The heat medium circulation flow path L6 is provided with a heat receiving portion 81 for receiving solar heat from condensed sunlight and a circulation pump 82 for circulating the heat medium. The heat medium heated by the heat receiving part 81 bypasses the water supply flowing into the flue 13 to the heat exchanger 83, thereby transferring heat to the water supply via the heat exchanger 83 for heat exchange. The boiler 10 generates steam by burning fuel to heat feed water that has exchanged heat with the heat medium. That is, the boiler 10 uses solar heat to generate steam.

The flue 13 is provided with a combustion gas passage 60 through which combustion gas passes. 45, economizers 46, 47 are arranged. Although the tertiary superheater 41, the secondary superheater 42, and the primary superheater 43 may be provided in series via a header, the header is omitted in FIG.

A steam turbine 61 driven by the steam generated by the boiler 10 includes, for example, a high pressure turbine 62 and a low pressure turbine 63 . The steam turbine 61 may further include an intermediate pressure turbine, and steam from the reheaters 44 and 45 (to be described later) may flow into the intermediate pressure turbine and then flow into the low pressure turbine 63 . Here, for the sake of convenience, the low-pressure turbine 63 is referred to as the presence or absence of the intermediate-pressure turbine.

A condenser 64 is connected to the low-pressure turbine 63, and the steam that drives the low-pressure turbine 63 is cooled by cooling water (eg, seawater) in the condenser 64 to become condensed water. The condenser 64 is connected to the inlet header 65 of the first economizer 47 via the water supply line L1. An inlet header 65 is provided in the combustion gas passage 60 . A water supply pump 66 is provided outside the combustion gas passage 60 in the water supply line L1. It can be bypassed and passed to heat exchanger 83 . The water heated by the heat exchanger 83 returns to the water supply line L<b>1 and is supplied to the inlet header 65 . A feed water heater (not shown) may be provided upstream of the on-off valve 85 of the feed water line L1, and feed water may be heated by steam extracted from the steam turbine 61. FIG. . The second economizer 46 is arranged above the first economizer 47 , and an intermediate header 67 is provided between the economizers 46 and 47 . An outlet header 68 is connected to the upper portion of the second economizer 46 , and the outlet header 68 is arranged outside the combustion gas passage 60 .

Here, a case where the boiler 10 is a drum boiler that generates subcritical pressure steam will be described. In this case, the outlet header 68 is connected to a steam drum 69 (steam separator) arranged outside the combustion gas passage 60 via a water supply line L2. The steam drum 69 is connected to each heat transfer tube (not shown) of the furnace wall and is connected to the primary superheater 43 . The primary superheater 43, the secondary superheater 42, and the tertiary superheater 41 are connected to the high pressure turbine 62 via the steam line L3. The high pressure turbine 62 is connected to the inlet header 70 of the first reheater 45 via a steam line L4. An inlet header 70 is provided in the combustion gas passage 60 and the first reheater 45 is connected to the second reheater 44 via an intermediate header 71 . An outlet header 72 is connected to the upper portion of the second reheater 44 , and the intermediate header 71 and the outlet header 72 are arranged outside the combustion gas passage 60 . The outlet header 72 is then connected to the low pressure turbine 63 via a steam line L5. Steam supplied from the outlet header 72 rotates the low pressure turbine 63 .

Therefore, when the combustion gas flows through the combustion gas passage 60 of the flue 13, the combustion gas passes through the tertiary superheater 41, secondary superheater 42, primary superheater 43, reheaters 44, 45, economizer 46, Heat is recovered in the order of 47. On the other hand, the water supplied from the feedwater pump 66 is preheated by the economizers 47 and 46, supplied to the steam drum 69, and heated while being supplied to each heat transfer tube of the furnace wall (not shown) to produce saturated steam. , and returned to the steam drum 69 .

The saturated steam in the steam drum 69 is introduced into the primary superheater 43, the secondary superheater 42 and the tertiary superheater 41 and superheated by the combustion gas. The superheated steam generated by the primary superheater 43, the secondary superheater 42, and the tertiary superheater 41 is supplied to the high pressure turbine 62 and drives the high pressure turbine 62 to rotate. The steam discharged from the high-pressure turbine 62 is introduced into the reheaters 45 and 44 to be heated again, and then supplied to the low-pressure turbine 63 to drive the low-pressure turbine 63 to rotate. A generator 3 is connected to the rotating shaft of the steam turbine 61 to generate power. The steam discharged from the low-pressure turbine 63 is cooled by the condenser 64 to become condensed water and sent to the economizers 47 and 46 again.

Here, a case (not shown) in which the boiler 10 is a once-through boiler that generates subcritical pressure steam or supercritical pressure steam will be described. In addition, the same code|symbol is attached|subjected and demonstrated to the component which is common in the case of the said drum-type boiler. In the once-through boiler, furnace wall tubes are provided between the economizer and the steam separator 69 , and the furnace wall tubes are composed of a plurality of heat transfer tubes provided so as to surround the furnace 11 . The water supplied from the feedwater pump 66 is heated by radiation from the flames in the furnace 11 when passing through the furnace wall tubes via the economizers 46 and 47 . Feedwater heated by passing through the furnace wall tubes is directed to a steam separator 69 . The steam separated by the steam separator 69 is supplied to the primary superheater 43, and the drain water separated by the steam separator 69 is led to the condenser 64 via the drain water pipe.

The steam superheated by each superheater (primary superheater 43, secondary superheater 42, and tertiary superheater 41) by exchanging heat with the combustion gas passes through the main steam pipe and is led to the high-pressure turbine 62 to produce high-pressure steam. Turbine 62 is driven to rotate. The steam discharged from the high-pressure turbine 62 is introduced into the reheater and heated again, and then supplied to the low-pressure turbine 63 to drive the low-pressure turbine 63 to rotate. A generator 3 is connected to the rotating shaft of the steam turbine 61 to generate power. The steam discharged from the low-pressure turbine 63 is cooled by the condenser 64 to become condensed water, and sent to the economizers 46 and 47 again.

(Arrangement of various sensors)
Arrangement of various sensors for performing measurements required for control of the boiler control device 100 provided in the power generation system 2 will be described below. A temperature sensor for measuring the outlet gas temperature of the air heater 49 is arranged at a position P1 shown in FIG. A thermocouple or the like can be used as the temperature sensor.

From the downstream side of the outlet of the feed water pump 66 shown in FIG. A temperature sensor for measuring the temperature of the feed water after heat exchange with the heat medium that receives solar heat is arranged at the position P2 of . A temperature sensor that measures the temperature of the water supply before heat exchange with the heat medium that receives the solar heat is arranged at the position P3. A flow rate sensor for measuring the flow rate of water supply and a pressure sensor for measuring the pressure of water supply may be arranged at either of the positions P2 and P3. However, the flow rate and pressure of the feed water bypassed to the heat exchanger 83 may be measured at locations other than the positions P2 and P3 as long as the same measurement values can be obtained. The pressure sensor may be omitted, and the flow rate sensor may be arranged only at one of the positions P2 and P3. Further, instead of the positions P2 and P3, for example, when the on-off valve 85 is used as a flow control valve to bypass only a part of the feed water to the heat exchanger 83, the position after the bypass merge from the feed water line L1 The above sensor may be provided at P12 and a position P13 before the bypass branch from the water supply line L1 across the on-off valve 85 .

A temperature sensor for measuring the outlet feed water temperature of the economizer 46 is arranged at the position P4. A temperature sensor for measuring the inlet steam temperature of the steam separator 69 is arranged at the position P5. A temperature sensor for measuring the outlet steam temperature of the secondary superheater 42 is arranged at the position P6.

(Configuration related to fuel flow rate control of boiler control device)
A schematic configuration of the boiler control device 100 according to one embodiment will be described below. FIG. 3 is a block diagram showing a configuration related to fuel flow rate control of the boiler control device 100 according to one embodiment.

The boiler control device 100 may be composed of an electric circuit or may be composed of a computer. When the boiler control device 100 is composed of a computer, it includes storage devices such as RAM (Random Access Memory) and ROM (Read Only Memory), and processors such as CPU (Central Processing Unit) and GPU (Graphics Processing Unit). and the processor implements its functions by executing the program stored in the storage device.

As shown in FIG. 3, the boiler control device 100 includes an information acquisition unit 110 that acquires various types of information necessary for control, and a first control signal that acquires a first control signal for the fuel flow rate of the fuel supplied to the boiler 10. An acquisition unit 120, a heat reception amount information acquisition unit 130 configured to acquire heat reception amount information, and correcting and controlling the fuel flow rate by obtaining heat transfer in the heat exchanger 83 from the heat medium in which the water supply receives the solar heat. A correction signal acquisition unit 140 configured to acquire a correction signal for, a fuel flow rate command unit 150 configured to output a fuel flow rate command for controlling the fuel flow rate, and a preceding fuel flow rate control and a correction unit 160 that corrects the third control signal for. As will be described later, the boiler control device 100 may further include an opening control section 170 (see FIG. 7) that controls the opening of the damper 56 .

The various information necessary for control includes information on the measured values of various sensors arranged in the power generation system 2 described above, information on the boiler load (the ratio of the amount of generated steam to the rated steam amount of the boiler system 1), generator output (power generation power generated by the generator 3). The received heat amount information is information related to the amount of heat received by the feed water through heat exchange with the heat medium that receives solar heat. The correction signal is a signal for converting the received heat amount indicated by the received heat amount information acquired by the received heat amount information acquisition unit 130 into a fuel flow rate and correcting the first control signal. Since this correction signal is used to correct the first control signal, it is distinguished from the correction of the third control signal by the correction section 160 .

The information acquisition unit 110 receives, as various types of information necessary for control, a generator output target command, one or more steam temperature deviations, information on the boiler load (current boiler load) and target boiler load, Acquire sensor information (for example, measured values of water supply pressure, flow rate, temperature difference, etc.).

The one or more steam temperature deviations are, for example, the deviation between the set value and the measured value of the secondary superheater outlet steam temperature and the deviation between the set value and the measured value of the steam temperature at the steam separator inlet. Either one of these deviations may be selected.

First, the generator output target command acquired by the information acquisition unit 110 and the deviation of one or more steam temperatures are input to the first control signal acquisition unit 120 . The first control signal acquisition unit 120 generates a base fuel flow rate signal indicating the base fuel flow rate to be supplied to the boiler 10 based on the input generator output target command. The first control signal acquisition unit 120 also generates a second control signal based on one or more input steam temperature deviations. The second control signal is a signal for correcting the base fuel flow signal based on one or more steam temperature deviations.

The second control signal is generated according to one or more steam temperature deviations so that, for example, about 10% to 20% of the base fuel is the maximum correction amount for the base fuel. Factors that cause one or more steam temperature deviations include, for example, changes in the heat transfer efficiency due to changes in the calorific value of coal and adhesion of ash to the heat transfer surfaces of the boiler. Normally, one or more steam temperature deviations may also occur due to fluctuations in the amount of heat received. However, in the boiler 10 according to the present embodiment, the boiler control device 100 performs control based on the received heat amount information, so the effect is considered to be small. The first control signal acquisition unit 120 inputs the generated base fuel flow rate signal and the second control signal to the comparator 121 to acquire the deviation.

Information about the boiler load and the target boiler load acquired by the information acquisition unit 110 is input to the first control signal acquisition unit 120 . The boiler load can be calculated, for example, from the values of measuring instruments (not shown) such as the pressure and temperature difference of the steam line L3, and the values of the flow meter (not shown) of the water supply line L1.

The first control signal acquisition unit 120 inputs a signal related to the boiler load to the function generator 124, inputs the boiler load change rate acquired from the signal related to the boiler load to the function generator 125, and outputs the function generators 124 and 125 is input to the multiplier 127 to obtain the multiplied value. The first control signal acquisition unit 120 acquires the load at the start of the load change from the signal related to the boiler load at the start of the boiler load change, and outputs the load at the start of the load change and the signal related to the target boiler load to the comparator 123. Enter to get the boiler load change range. The first control signal acquisition unit 120 inputs the boiler load change width to the function generator 126 . The output signal of function generator 126 and the output signal of multiplier 127 are input to multiplier 128 . The output signal of this multiplier 128 is acquired as the third control signal according to the boiler load condition.

The third control signal is a signal for improving the responsiveness (quick response) of the fuel flow rate control by temporarily changing the fuel flow rate for the boiler load from the base fuel flow rate and outputting it. Used for flow control. Therefore, this signal may temporarily output a fuel flow rate command that indicates a fuel flow rate that exceeds the maximum value of the base fuel flow rate in steady fuel flow rate control.

The information on the boiler load and the target boiler load acquired by the information acquisition unit 110 is input to the correction unit 160 of the first control signal acquisition unit 120 . The correction unit 160 inputs the boiler load-related signal to the function generator 164, inputs the boiler load change rate obtained from the boiler load-related signal to the function generator 165, and outputs the function generators 164 and 165 to the multiplier 167. to get the multiplied value. The correction unit 160 inputs the signal related to the boiler load at the start of boiler load change and the signal related to the target boiler load to the comparator 163 , acquires the deviation, and inputs the deviation to the function generator 166 . The output signal of function generator 166 and the output signal of multiplier 167 are input to multiplier 168 .

Here, the function generators 164, 165, 166 of the correction unit 160 have different functions from the function generators 124, 125, 126 for obtaining the third control signal. The signal input to the multiplier 168 is a signal for correcting the third control signal for preceding fuel flow rate control for improving the responsiveness (quick response) of the fuel flow rate control. used for

The sensor information necessary for calculating the received heat amount acquired by the information acquisition unit 110 is input to the received heat amount information acquisition unit 130 . The received heat amount information acquisition unit 130 calculates the received heat amount based on the sensor information.

Specifically, the received heat amount information acquisition unit 130 determines the temperature difference of the water supply (in the example shown in FIG. The temperature difference between the temperature and the feed water temperature at the position P3) is obtained, and the amount of heat received is calculated based on the temperature difference, the flow rate of the feed water obtained from the flow sensor, and the specific heat obtained from the pressure of the feed water. For example, the received heat amount information acquisition unit 130 acquires the temperature difference of the feed water temperature from the measured values of the temperature sensors provided at the positions P2 and P3, multiplies it by the specific heat of the feed water, and converts the value to the specific enthalpy. Calculated as the amount of change. Furthermore, the received heat amount information acquisition unit 130 multiplies the value by the flow rate of the water supply acquired from the flow sensor, and calculates the value as the received heat amount.

Since the flow rate and pressure of the feed water usually do not change significantly between the positions before and after heat exchange with the heat medium (the positions before and after the heat exchanger 83), they may be regarded as constant and measured by a single flow sensor. However, if the on-off valve 85 is configured to be a flow control valve so that the flow rate of feed water bypassed from the feed water line L1 to the heat exchanger 83 is part of the feed water line L1, bypassing to the heat exchanger 83 The flow rate is obtained from the flow sensor, and the multiplication value of the specific enthalpy and the flow rate is obtained from the temperature sensors and the flow rate sensors at the positions P3 and P2 before and after the bypassed heat exchanger 83, and the difference between them is obtained in the heat exchanger 83. It may be calculated as the amount of heat received by the water supply. A position P13 is provided before the bypass branch from the water supply line L1 across the on-off valve 85, and a position P12 is provided after the bypass merge from the water supply line L1. , and the difference between them may be calculated as the amount of heat received by the heat exchanger 83 from the feed water.

As a modification of this embodiment, it may be necessary to control the circulation flow rate of the heat medium in the heat medium circulation flow path L6 in order to improve the heat receiving efficiency of the solar heat. At this time, when obtaining the solar heat reception information, if the flow rate of the heat medium is configured to change between the front and rear positions of the heat receiving section 81, the flow rates of the front and rear positions of the heat receiving section 81 are obtained from the flow sensors, and For each position, the multiplication value of the specific enthalpy and the flow rate is obtained from the temperature sensor and the flow sensor, and the difference between them is calculated as the amount of solar heat received by the heat receiving part 81, and the circulation flow rate of the heat medium in the heat medium circulation flow path L6 is calculated. may be controlled. Also, the amount of solar heat received may be calculated in consideration of changes in pressure. For example, the received heat amount information acquisition unit 130 acquires the measured values of the pressure of the water supply at the front and rear positions where heat is exchanged with the heat medium from the pressure sensors, and adds these measured values to calculate the specific enthalpy at the front and rear positions. may be configured to calculate the specific enthalpy difference more accurately. In addition, for example, when the heat medium undergoes a phase change, it is necessary to evaluate the amount of latent heat absorbed. values are obtained from the pressure sensors, and the enthalpies at the front and rear positions are calculated in consideration of the measured values. may be configured to control the

Received heat amount information indicating the amount of received heat calculated by the received heat amount information acquisition unit 130 is input to the correction unit 160 . The correction unit 160 calculates the heat reception increase amount at the monitoring portion (heat exchanger 83) from the heat reception amount information, and converts it into a fuel flow rate. The correction unit 160 inputs to the multiplier 169 a signal indicating the result of converting the increased amount of heat received into a fuel flow rate and the output signal of the multiplier 168 . The output signal of the multiplier 169 is input to the comparator 129 together with the output signal of the multiplier 128 which is the third control signal. As a result, the third control signal can be used for preceding fuel flow rate correction control in which the correction section 160 corrects the third control signal.

Here, correction conditions of the correction unit 160 will be described. When the measured value of the boiler load at the start of the boiler load change, the rate of change of the boiler load, and the width of change of the boiler load satisfy predetermined conditions, the correction unit 160 determines whether the fuel is more advanced than when the predetermined conditions are not satisfied. The third control signal is corrected by the preceding fuel flow rate correction control by the correction section 160 so as to decrease the fuel flow rate commanded as the flow rate by the third control signal. The predetermined condition is, for example, various boiler load conditions such that at least one of the steam temperature at the furnace outlet and the steam temperature at the primary superheater outlet has a tolerance for the allowable upper limit temperature as a specification such as the material and structure of the heat exchanger below a reference value. It is the condition of values (boiler load value, boiler load change rate, boiler load change range, etc.).

As a configuration for determining whether or not a predetermined condition is satisfied, for example, the function generators 164, 165, and 166 of the correction unit 160 are configured such that, for example, when the boiler load increases, the steam temperature or the feed water temperature rises to the heat exchanger The tolerance for the allowable upper limit temperature as the specification of is below the reference value, and only when the boiler load change rate and the boiler load change width are larger than the predetermined values, the multiplier 169 outputs a signal to decrease the fuel flow rate. function is set. That is, when the predetermined condition is not satisfied, the function is set so that the amount of decrease due to the prior fuel flow rate correction control to the fuel flow rate commanded as the prior fuel flow rate by the correction of the correction section 160 is zero.

Further, the correction unit 160 determines the decrease amount of the fuel flow rate in the correction by the preceding fuel flow rate correction control to the fuel flow rate commanded as the preceding fuel flow rate of the third control signal based on the received heat amount indicated by the received heat amount information. configured to For example, the correction unit 160 multiplies the received heat amount indicated by the received heat amount information by a coefficient (for example, a coefficient set in advance through a simulation or an actual machine test). 0.6 times the amount of increase in heat received) may be converted into a fuel flow rate and determined as the amount of decrease in the fuel flow rate.

The first control signal acquisition unit 120 inputs the output signal of the comparator 121 and the output signal of the comparator 129 to the adder 122 and acquires the output signal of the adder 122 as the first control signal. The received heat amount information indicating the received heat amount calculated by the received heat amount information acquisition unit 130 is input not only to the correction unit 160 but also to the correction signal acquisition unit 140 . The calculation of inputting the output signal of the multiplier 168, which is the preceding fuel flow rate correction control signal, and the output signal of the multiplier 128, which is the third control signal, to the comparator 129 is performed by the first control signal acquisition section 120. Instead of performing the operation as a calculation in the correction signal acquisition unit 140, the output signal of the adder 122 may be used as the first control signal.

The correction signal acquisition unit 140 converts the received heat amount indicated by the input received heat amount information into a fuel flow rate, and acquires a correction signal for correcting the first control signal and its delay element based on the conversion result. The correction signal acquisition unit 140 outputs a signal obtained by adding a delay element to the correction signal, and holds the current fuel flow rate without correction for the time corresponding to the delay element.

The delay element is, for example, a first-order lag element having a time constant from the amount of heat retained by the economizers 46 and 47 to the change in the heat receiving amount of the heat receiving part 81 until the temperature of the outlet water supply of the economizers 46 and 47 changes. By delaying the start of correction of the preceding fuel flow rate with respect to the change in the amount of heat received by the unit 81, the time until the change in the amount of heat received with respect to the boiler load settles is taken into consideration. In this case, the time constant of change in outlet feed water temperature of economizers 46 and 47 is set to 0 to 600 seconds, for example. The time constant corresponding to the delay element is set in advance by, for example, a simulation or an actual machine test, and may be set to 0 seconds for boiler load changes that do not require a delay element, for example. Note that the delay element is not limited to such a first-order delay element, and may be one that adds dead time (delay time) to the correction signal, or may be a second-order delay element.

The output signal (correction signal to which the delay element is added) of the correction signal acquisition section 140 and the output signal (first control signal) of the adder 122 are input to the comparator 145 . The output signal of comparator 145 is input to fuel flow command section 150 . That is, fuel flow rate command section 150 outputs a fuel flow rate command based on the first control signal and the correction signal to which the delay element is added.

(Significance of fuel flow rate control of boiler control device)
The significance of the fuel flow rate control by the above-described boiler control device 100 will be described below. Here, a boiler control device according to a comparative example will be described. However, illustration of the detailed configuration is omitted. A boiler according to a comparative example includes a heat exchanger that exchanges heat from a heat medium that receives solar heat to bypassed feed water, an economizer, a furnace, a primary superheater, a secondary superheater, and a tertiary superheater. Prepare. The control device of the boiler according to the comparative example prevents the feed water temperature or steam temperature from reaching the allowable upper limit temperature as the specification of the heat exchanger when the main steam temperature exceeds the reference high temperature. A portion of the feed water going to the coalger is branched and supplied to the primary superheater outlet and the secondary superheater outlet. Such a bypass supply of feedwater acts as spray water and reduces the steam temperature at the primary and secondary superheater outlets.

FIG. 4 is a conceptual diagram for explaining temperature distribution in a boiler according to a comparative example. This figure shows the temperature distribution of the feed water temperature or the steam temperature that changes from the upstream side to the downstream side. In the example shown in FIG. 4, the primary superheater outlet temperature and the secondary superheater outlet temperature are reduced by the bypass supply of feedwater acting as spray water, as described above. This figure shows the temperature distribution of feed water temperature or steam temperature with the amount of heat received (amount of heat received through heat exchange with a heat medium that receives heat from the sun) indicated by the dashed line and the amount of heat received from the solar heat indicated by the solid line. It is shown in a graph form that can be distinguished from the case without . A comparison of both shows that even if the amount of heat received fluctuates, fluctuations in the steam temperature at the outlet of the secondary superheater on the downstream side are suppressed. This is because the spray water is controlled based on the main steam temperature. However, in the boiler according to the comparative example, focusing on the economizer outlet temperature, the furnace outlet temperature, and the primary superheater outlet temperature, it can be seen that these temperatures increase as the amount of heat received increases. Therefore, these temperatures may reach the allowable upper limit temperature of the heat exchanger.

On the other hand, in the above-described boiler control device 100, the third control signal instructing the preceding fuel flow rate obtained by the multiplier 128 and the fuel flow rate command obtained by the correcting section 160 and the multiplier 128 are reduced by the amount of decrease in the fuel flow rate. The preceding fuel flow rate correction signal is calculated by the adder 122, and the correction signal corresponding to the received heat amount obtained by the received heat amount information acquisition unit 130 is calculated by the comparator 145, so that the fuel flow rate command is output, and the fuel Properly control the flow rate. Therefore, the temperature upstream of the primary superheater outlet temperature is also controlled. Therefore, the temperature distribution in the boiler 10 (for example, the temperature distribution from the inlets of the economizers 46 and 47 to the outlet of the primary superheater 43) can be optimized with respect to fluctuations in the amount of heat received. It is possible to suppress the distribution from reaching the allowable upper limit temperature as the specification of the heat exchanger. Moreover, when the amount of heat received varies greatly, the fuel flow rate is more appropriately reduced from the preceding fuel flow rate supplied to the boiler 10, so the fuel consumption of the boiler can be reduced.

FIG. 5 is a diagram for explaining correction by the correction unit 160 with respect to the third control signal used for preceding fuel flow rate control according to the load state of the boiler control device 100 according to one embodiment. 10 is a conceptual diagram showing temporal transition of steam temperature (outlet temperature of primary superheater 43). First, when the boiler load is suddenly increased so as to maintain the generator output in response to a sudden decrease in the amount of heat received, or when a sudden change in the output request of the generator 3 (a sudden increase in the target boiler load) occurs. In this case, in order to improve the responsiveness (quick response) of the fuel flow rate control to an increase in the boiler load, prior fuel flow rate control is performed in which the fuel flow rate to be supplied to the boiler 10 is precedently introduced.

Here, when the third control signal is not corrected as shown in FIG. 5, and when the boiler load is rapidly increased as shown by the solid line, the steam temperature at the outlet of the primary superheater 43 of the boiler 10 is It was found that the allowable upper limit temperature as the specification of the heat exchanger was approached and sometimes reached the allowable upper limit temperature. On the other hand, according to the boiler control device 100, when predetermined conditions (various conditions such as boiler load value, boiler load change rate, boiler load change width, etc.) are satisfied, advance input by the third control signal Correction by preceding fuel flow rate correction control by the correction unit 160 is performed so that the fuel flow rate to be reduced decreases. As a result, the boiler load can be rapidly increased in the event of a sudden increase in the boiler load due to a sudden decrease in the amount of heat received, or in the event of a sudden change in the output demand of the generator 3 (rapid increase in the target boiler load). Even in this case, as shown by the dashed line, the tolerance for the allowable upper limit temperature as the specification of the heat exchanger of the steam temperature is increased more than when there is no correction by the correction unit 160 of the third control signal shown by the solid line. be able to.

FIG. 6 is a diagram for explaining the correction of the third control signal of the boiler control device 100 according to one embodiment, and is a conceptual diagram showing the temporal transition of the fuel flow rate of the boiler 10. As shown in FIG. This figure shows the fuel flow rate when there is a sudden increase in the boiler load when the amount of received solar heat drops sharply, or when there is a sudden change in the output demand of the generator 3 (a sudden increase in the target boiler load). It shows the transition of The solid line is the base fuel flow rate according to the target boiler load. On the other hand, in order to improve the responsiveness (quick response) of the fuel flow rate control when the boiler load is increased, the fuel flow rate larger than the base fuel flow rate is preceded by the third control signal. If there is no correction after addition of the corresponding fuel flow rate, as shown by the dash-dotted line, the time to put in a larger fuel flow rate than the base fuel flow rate will be longer, and after a temporary overshoot, the set value of the base fuel flow rate will be reached. calm down.

However, if the fuel flow rate in the portion where the fuel flow rate overshoots is large, the steam temperature at the outlet of the primary superheater 43, for example, approaches the allowable upper limit temperature as the specification of the heat exchanger, as described above. from the viewpoint of optimizing the temperature distribution in the boiler 10 . In this regard, according to the boiler control device 100, when predetermined conditions (boiler load value, boiler load change rate, boiler load change width, etc.) are satisfied, the third control signal is corrected The advance fuel correction control by the unit 160 corrects the fuel flow rate of the fuel flow rate command so as to decrease. As a result, the preceding fuel flow rate in the overshooting portion is reduced as indicated by the dashed line in the figure. Thereby, it becomes possible to appropriately reduce the fuel consumption amount from the preceding fuel flow rate supplied to the boiler 10 . In particular, the larger the change in the amount of heat received from the heat medium that received heat from the solar heat to the water supply bypassed by the heat exchanger 83, the more appropriately the reduction amount of the fuel consumption amount is adjusted from the preceding fuel flow rate. The reduction amount of the fuel supply amount to the boiler 10 can be increased.

(Structure related to opening control of damper of boiler control device)
Hereinafter, the configuration related to the opening degree control of the damper 56 of the boiler control device 100 will be described. FIG. 7 is a block diagram showing a configuration related to opening degree control of the damper 56 of the boiler control device 100 according to one embodiment.

As shown in FIG. 7 , the boiler control device 100 includes an information acquisition unit 110 and an opening control unit 170 that controls the opening of the damper 56 . In order to improve the responsiveness (quick response) of the fuel flow rate control when increasing the boiler load, the preceding fuel flow rate is commanded by the preceding fuel correction control by the correction unit 160 from the above-mentioned third control signal. Correction is made so that the fuel flow rate decreases. This correction has the effect of lowering the steam temperature at the outlet of the primary superheater 43 from the allowable upper limit temperature as the specification of the heat exchanger. However, if this effect is insufficient and the steam temperature at the outlet of the primary superheater 43 is not sufficiently lowered, the opening degree of the damper 56 is controlled by the opening degree control section 170 . The opening degree of the damper 56 may be controlled by the opening degree control section 170 without using the preceding fuel correction control by the correction section 160 .

The information acquisition unit 110 acquires various types of information necessary for controlling the opening degree of the damper 56 . Various information necessary for controlling the opening degree of the damper 56 is, for example, information on the outlet water temperature of the economizers 46 and 47 acquired from each temperature sensor, the deviation of the outlet gas temperature of the air heater 49 from the target temperature, and the denitrification device. 50, including information indicating the deviation of the inlet gas temperature from the target temperature. The expression "outlet feed water temperature of the economizers 46 and 47" means the outlet feed water temperature of the economizer 47. FIG. That is, in the boiler 10 having only one economizer, the opening of the damper 56 may be controlled using the temperature of the outlet feed water of the economizer. ), the opening of the damper 56 may be controlled based on the outlet feed water temperature of the economizer (e.g., the economizer 47) that tends to reach high temperatures.

First, the information about the outlet feed water temperature of the economizers 46 and 47 acquired by the information acquisition section 110 is input to the comparators 171 and 172 of the opening degree control section 170 . A comparator 171 compares the first set temperature with the outlet feed water temperature of the economizers 46 and 47 and outputs a deviation. The first set temperature is set, for example, to a value lower than the saturated steam temperature of the outlet feed water temperature of the economizers 46, 47 by 5° C. to 10° C. as a margin, and steaming in the economizers 46, 47 is performed. Suppress.

The output signal of comparator 171 is input to PI control section 173 . The PI control section 173 performs proportional integral control (PI control) based on the output signal of the comparator 171 and the feedback signal of the opening of the damper 56 . In addition, as an example, a value 10° C. lower than the saturated steam temperature is set as the margin of the outlet feed water temperature of the economizers 46 and 47 with respect to the saturated steam temperature, and the PI control unit 173 sets the temperature difference of 10° C. or more as the tracking condition. It is tracked and determines whether PI control of the opening of the damper 56 is necessary. In addition, it is preferable that the feed water is prevented from being vaporized due to steaming in the economizers 46 and 47 due to the specifications of the heat exchangers. Therefore, it goes without saying that the tolerance is the difference between the outlet feed water temperature and the saturated steam temperature so that the outlet feed water temperature of the economizers 46 and 47 does not exceed the saturated steam temperature.

The switching unit 175 performs switching depending on whether the tolerance is 10° C. or higher. The switching unit 175 outputs the result of inputting the opening degree of the economizer outlet damper to the function generator 176 when the margin is 10° C. or more, but when the margin is less than 10° C. , the output signal of the PI control unit 173 is output to control the opening of the damper 56 so that the margin does not fall below 10.degree. An economizer outlet damper (not shown) is separate from the damper 56 for bypassing the economizers 46 , 47 and is installed downstream of the economizers 46 , 47 to share flow with the bypass flow path 55 . and differential pressure adjustment (because the pressure loss coefficients of the bypass channel and the main channel are different). As described above, if the temperature margin is sufficient, the damper 56 is set to a programmed opening relative to the opening of the economizer outlet damper.

A comparator 172 compares the second set temperature with the outlet feed water temperature of the economizers 46 and 47 and outputs a deviation. The second preset temperature is set to a value that is 15° C. lower than the saturated steam temperature of the economizers 46 and 47, for example. That is, the second set temperature is set to a temperature lower than the first set temperature. As will be described later, this is because the margin is increased to ensure that the economizers 46 and 47 are in a stable state when there is a high risk of reaching the saturated steam temperature due to, for example, a large margin reduction rate (decrease speed of the margin). This is to suppress teaming.

Further, when the opening of the damper 56 is controlled using the outlet feed water temperature of the economizers 46 and 47, the temperature of the combustion gas in the flue 13 and the gas duct 48 of the boiler system 1 is Since there is a possibility that the specified temperature may be reached in the equipment on the downstream side, it is preferable to set the opening of the damper 56 to the minimum opening so as not to open more than necessary. The denitrification device 50, the air heater 49, etc. may reach the specified temperature in the equipment on the downstream side.

Therefore, at least one of the outlet gas temperature of the air heater 49 and the inlet gas temperature of the denitration device 50 is monitored. FIG. 7 shows, as an example, the case of monitoring both the outlet gas temperature of the air heater 49 and the inlet gas temperature of the denitrification device 50 . Since there is a difference of more than double the temperature change range between the outlet gas temperature of the air heater 49 and the inlet gas temperature of the denitrification device 50 when the damper opening is increased, the deviation of the denitrification device 50 is adjusted to equalize each gas temperature deviation. should be doubled. Therefore, the switch 179 selects the larger one of the temperature deviation of the outlet gas of the air heater 49 and the deviation of the temperature deviation of the inlet gas of the denitrification device 50, and inputs it to the AND circuit.

The output signal of the comparator 172 is input to the P control section 174 that performs proportional control. The output signal of P control section 174 is input to switching section 177 . The switching unit 177 determines whether the temperature deviation selected by the switch 179 and the tolerance decrease rate (rate of tolerance decrease) are equal to or greater than a reference value, and whether the tolerance is equal to or less than a reference value (for example, 15° C.). Switching is performed based on the AND condition of whether or not. For example, when the tolerance is 15° C. or less, the rate of decrease of the tolerance is equal to or greater than the reference value, and the temperature deviation is equal to or greater than the reference value, the switching unit 177 sets the correction amount of the opening of the damper 56 to the P control unit 174 output signals. On the other hand, if not, the switching unit 177 outputs zero by initializing the correction amount of the damper opening to 0%.

The output signals of the switching units 175 and 177 are input to the adder 178 , and the addition result thereof is output as the minimum opening degree of the damper 56 . That is, when there is a high possibility that the water supply outlet temperature of the economizers 46 and 47 reaches the saturated steam temperature, the minimum opening degree of the damper 56 is controlled to be increased. Otherwise, the opening of the damper 56 is controlled at the minimum opening for adjusting the temperatures of the denitrification device 50 and the air heater 49 .

The opening degree control unit 170 is controlled by the difference between the outlet feed water temperature and the saturated steam temperature of the economizers 46 and 47 and the decreasing speed of the difference between the outlet feed water temperature and the saturated steam temperature of the economizers 46 and 47. Based on this, the opening degree of the damper 56 may be controlled. Further, the opening degree control section 170 may control the opening degree of the damper 56 to the minimum opening degree based on the outlet gas temperature of the air heater 49 or the inlet gas temperature of the denitrification device 50 .

For example, the opening degree control unit 170 determines that the difference between the outlet feed water temperature of the economizers 46 and 47 and the saturated steam temperature is equal to or less than a reference value, When any one of the conditions that the rate of decrease of the difference is equal to or higher than the reference value, or that the temperature of the outlet gas of the air heater 49 or the inlet gas temperature of the denitration device 50 is equal to or higher than the reference value, the opening degree of the damper 56 is is increased to suppress the steaming of the economizers 46 and 47, and the opening of the damper 56 may be controlled to the minimum opening without opening more than necessary. When the opening of the damper 56 is controlled so that the temperature at the outlet of the air heater 49 is taken into consideration so that the temperature of the denitration device 50 and the air heater 49 is less than the specified temperature, the reaction temperature of the denitration device 50 should be ensured and the corrosion of the air heater 49 should be suppressed. can be done.

(Significance of damper opening control of boiler control device)
The significance of the damper opening degree control by the above-described boiler control device 100 when the boiler load of the boiler 10 is reduced will be described below. FIG. 8 is a diagram for explaining damper opening degree control of the boiler control device 100 according to an embodiment. When a sudden change in output demand occurs (sudden reduction in target boiler load), etc., when the boiler load is suddenly reduced, the outlet feedwater temperature of the economizers 46 and 47 accompanying the reduction in boiler load It is a conceptual diagram which shows a temporal transition.

As shown in FIG. 8, when the boiler load of the boiler 10 decreases, the feed water pressure decreases, and the saturated steam temperature indicated by the dashed line also decreases. When the boiler load decreases from a state in which the outlet feed water temperature of the economizers 46 and 47 is high due to high boiler load operation such as rated operation due to the amount of heat received, the heat possessed by the economizers 46 and 47 reduces the temperature. The drop in feed water temperature becomes slower, and the rate of drop in saturated steam temperature becomes faster. Therefore, when the opening control of the damper 56 is not performed as described above, the outlet feed water temperature of the economizers 46 and 47 decreases with time as indicated by the solid line. As a result, the tolerance of the outlet feed water temperature of the economizers 46 and 47 to the saturated steam temperature becomes small, and there is a risk that steam will be generated at the outlets and inside of the economizers 46 and 47 .

On the other hand, when the opening degree of the damper 56 is controlled as indicated by the dotted line, the opening degree of the damper 56 is increased, and part of the high-temperature gas flowing into the economizers 46 and 47 is branched into nodes. Since the carbonizers 46, 47 are induced to bypass, the feed water temperature of the economizers 46, 47 is quickly lowered. As a result, the tolerance of the outlet feed water temperature of the economizers 46 and 47 with respect to the saturated steam temperature increases.

On the other hand, when reducing the boiler load, the responsiveness (quick response) of the fuel flow rate control is improved by the above-mentioned third control signal, and the fuel flow rate is appropriately corrected to the fuel flow rate command commanded as the preceding fuel flow rate. However, it takes time to lower the outlet feed water temperature of the economizers 46 and 47 due to the reduction in the fuel flow rate to the boiler 10 . Compared to this, the control of the opening degree of the damper 56 directly lowers the outlet water temperature of the economizers 46 and 47, so high responsiveness and high temperature reduction effect can be obtained. Therefore, when reducing the boiler load, the control of the opening degree of the damper 56 may be given priority over the suppression of steaming at the outlets of the economizers 46 and 47 .

(Flow of control processing)
A specific example of the control process executed by the boiler control device 100 will be described below. Although the processing relating to the fuel flow rate control will be described here, the control processing may be modified to a processing that combines the processing for controlling the opening degree of the damper 56 . FIG. 9 is a flowchart showing an example of control processing executed by the boiler control device 100 according to one embodiment.

As shown in FIG. 9, the boiler control device 100 acquires a base fuel flow rate signal based on the generator output target command (step S1). The boiler control device 100 acquires a second control signal based on one or more steam temperature deviations (step S2). The boiler control device 100 acquires a third control signal for preceding fuel flow rate control based on the boiler load condition (step S3). Here, the boiler control device 100 determines whether predetermined conditions (boiler load value, boiler load change rate, boiler load change width, etc.) are satisfied (step S4). For this determination, for example, the function generators 164, 165, and 166 shown in FIG. 3 set the function so that the correction amount is zero when the predetermined condition is not satisfied, and the correction amount is not zero when the predetermined condition is satisfied. It may be realized by being executed, or may be realized by arithmetic processing by software.

Here, when it is determined that the predetermined condition is satisfied (step S4; Yes), the boiler control device 100 corrects the third control signal by preceding fuel flow rate correction control (step S5). On the other hand, when it is determined that the predetermined condition is not satisfied (step S4; No), the boiler control device 100 skips the process of step S5.

Next, the boiler control device 100 acquires the first control signal based on the base fuel flow rate signal, the second control signal, and the third control signal (correction has been determined by the preceding fuel flow rate correction control) (step S6 ). The boiler control device 100 acquires received heat amount information indicating the amount of heat transferred to the feed water (step S7). The boiler control device 100 converts the received heat amount indicated by the received heat amount information into a fuel flow rate and acquires a correction signal (step S8). The boiler control device 100 outputs a fuel flow rate command based on the first control signal and the correction signal to which the delay element is added (step S9).

The present disclosure is not limited to the above-described embodiments, and includes modifications of the above-described embodiments and modes in which these modes are combined as appropriate.

(Modification)
For example, the order of the control processes executed by the boiler control device 100 is not limited to the example shown in FIG. 9, and can be changed as appropriate. Also, some processing may be omitted.

The boiler control device 100 according to some of the embodiments described above may be configured to implement all or part of the above processing by software. In this case, the boiler control device 100 includes a processor such as a CPU or GPU, a storage device such as RAM and ROM, and a computer-readable recording medium in which a program for realizing all or part of the above processing is recorded. Prepare.

Then, the processor reads out the program recorded in the storage medium and executes information processing and arithmetic processing, thereby realizing processing similar to that of the boiler control device 100 described above. Computer-readable recording media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like. Alternatively, such a program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program.

In the above-described embodiment, as an example of receiving fluctuating heat from the outside, solar heat due to condensed sunlight was used, but the present invention is not limited to this. The fluctuating external heat includes factory exhaust heat, combustion heat and exhaust heat from by-product gases with fluctuating fuel composition and fuel amount, and biomass fuel combustion heat and exhaust heat with fluctuating fuel composition and fuel amount. can be used.

Further, in the above-described embodiment, the boiler is the coal-fired boiler 10, but as a solid fuel, a boiler that uses biomass fuel, PC (petroleum coke) fuel generated during petroleum refining, petroleum residue, etc. may Further, the fuel is not limited to solid fuel, and the boiler may be a boiler that uses liquid fuel such as heavy oil. Furthermore, gaseous fuel (such as by-product gas) can also be used as the fuel. The boiler can also be applied to mixed combustion of these fuels.

(summary)
The contents described in each of the above embodiments are understood as follows, for example.

(1) A boiler control device (100) according to an embodiment of the present disclosure,
A boiler control device (100) for generating steam from feed water,
A first control signal for acquiring a first control signal for generating a fuel flow rate of fuel to be supplied to the boiler based on a base fuel flow rate signal generated based on the output target command and a third control signal according to the boiler load condition an acquisition unit (120);
a received heat amount information acquisition unit (130) configured to acquire received heat amount information relating to the amount of heat received that fluctuates from the outside;
A correction signal configured to acquire a correction signal for correcting the first control signal by converting the received heat amount indicated by the received heat amount information acquired by the received heat amount information acquisition unit (130) into the fuel flow rate. an acquisition unit (140);
a fuel flow rate command unit (150) configured to output a fuel flow rate command for controlling the fuel flow rate based on the first control signal and the correction signal to which a delay element is added;
Prepare.

According to the configuration described in (1) above, the amount of heat received from fluctuating heat from the outside is converted into a fuel flow rate for the first control signal generated based on the output target command and the boiler load condition. Corrected by the signal, a fuel flow command is output to control the fuel flow. Therefore, it becomes possible to more appropriately control the fuel flow rate with respect to fluctuations in the amount of heat received from fluctuating heat from the outside. This makes it possible to control the boiler (10) so as to satisfy the operating conditions, and for example, fuel to be supplied to the boiler (10) according to the amount of heat received from fluctuating external heat such as solar heat. The flow rate can be reduced to reduce fuel consumption. Further, by correcting the first control signal, the temperature distribution in the boiler (10) (for example, the temperature distribution from the inlet of the economizer (46, 47) to the outlet of the primary superheater (43) is ) can be made more appropriate.

In addition, as a result of intensive studies by the inventors of the present application, it has been found that appropriate control cannot be achieved if the fuel flow rate is controlled immediately in response to changes in the amount of heat received. There is a time lag between the timing when the amount of heat received changes and the timing when the temperature distribution in the boiler (10) changes due to the change. This is due, for example, to the residual heat of a heat exchanger provided in the boiler (10). Under such conditions, when the fuel flow rate is controlled in accordance with the timing at which the amount of heat received changes, it is considered that the timing of the control is too early and appropriate control cannot be performed.

In this respect, according to the configuration described in (1) above, since a delay element is added to the correction signal, it is possible to adjust the timing of controlling the fuel flow rate with respect to the amount of heat received, so that an appropriate fuel flow rate can be controlled.

(2) In some embodiments, in the configuration described in (1) above,
The lag element is a first-order lag element having a time constant of change in outlet feed water temperature of the economizer (46, 47) with respect to change in the received heat amount.

According to the configuration described in (2) above, it is possible to reduce the possibility that the outlet feed water temperature of the economizer (46, 47) deviates from the allowable range as the specification of the heat exchanger. In addition, by optimizing the outlet feed water temperature of the economizers (46, 47), the temperature at a more downstream position (eg, the outlet steam temperature in the primary superheater (43)) is also regulated concomitantly. be able to.

(3) In some embodiments, in the configuration described in (1) or (2) above,
The first control signal acquisition unit (120) generates the first control signal based on the base fuel flow rate signal and a second control signal generated based on one or more steam temperature deviations.

According to the configuration described in (3) above, the first control signal is generated based on one or more steam temperature deviations, and the fuel flow rate command is generated based on the first control signal and the correction signal. Therefore, it becomes possible to perform control so as to satisfy the operating conditions of the boiler (10).

(4) In some embodiments, in the configuration described in (3) above,
The first control signal acquisition unit (120), when the measured value of the boiler load, the rate of change of the boiler load, and the width of change of the boiler load satisfy predetermined conditions, is higher than when the predetermined conditions are not satisfied. A corrector (160) is included to correct the third control signal to decrease the fuel flow rate.

According to the configuration described in (4) above, when predetermined conditions (boiler load value, boiler load change rate, boiler load change width, etc.) are satisfied, the first Prior fuel flow rate correction control is performed to reduce the prior fuel flow rate more than when the control signal 3 does not satisfy the predetermined condition. As a result, a correction to the third control signal is performed to reduce the preceding fuel flow rate, thereby more appropriately reducing the fuel flow rate from the preceding fuel flow rate supplied to the boiler (10), thereby reducing fuel consumption. becomes possible.

Moreover, it is possible to optimize the temperature distribution in the boiler (10) with respect to fluctuations in the boiler load. For example, when the boiler load increases, it is possible to reduce the possibility that the furnace outlet steam temperature or the primary superheater outlet steam temperature will exceed the allowable upper limit temperature according to the specifications of the heat exchanger. For example, when the boiler load is reduced, the temperature of the feed water at the outlet of the economizer can be lowered to reduce the possibility that the temperature of the feed water at the outlet of the economizer reaches the saturated steam temperature.

(5) In some embodiments, in the configuration described in (4) above,
The correction unit (160) determines the amount of decrease in the fuel flow rate in correcting the third control signal based on the amount of received heat indicated by the information on the amount of received heat.

According to the configuration described in (5) above, the amount of decrease in the fuel flow rate is determined based on the amount of heat received from fluctuating heat from the outside, so the fuel flow rate can be controlled more appropriately.

(6) In some embodiments, in the configuration described in any one of (1) to (5) above,
an opening control unit (170) for controlling the opening of a damper (56) provided in a bypass flow path (55) for bypassing the economizer (46, 47);
The opening degree control unit (170) is controlled based on the difference between the outlet water supply temperature of the economizer and the saturated steam temperature, and the rate of decrease of the difference between the outlet water supply temperature of the economizer and the saturated steam temperature. to control the opening of the damper.

According to the configuration described in (6) above, the damper ( 56) is controlled. When the damper (56) is controlled to have a large opening, the amount of hot gas flowing into the bypass flow path (55) increases and the amount of hot gas flowing into the economizers (46, 47) decreases. The outlet feedwater temperature of the coalger (46, 47) is lowered. Therefore, it is possible to reduce the possibility that the outlet feed water temperature of the economizer (46, 47) reaches the saturated steam temperature and causes steaming.

(7) In some embodiments, in the configuration described in any one of (1) to (6) above,
The received heat amount information acquisition unit (130) obtains the received heat amount based on the temperature difference and the flow rate of the water supply at positions before and after the position where heat is transferred from the heat medium that receives the fluctuating heat from the outside to the water supply. calculate.

According to the configuration described in (7) above, the state of the water supply is compared at positions before and after the position where heat is transferred from the heat medium that receives fluctuating heat from the outside to the water supply by the heat exchanger, and the amount of heat received is calculated. Since the calculation is performed directly, the received heat amount can be calculated more accurately.

(8) In some embodiments, in the configuration according to any one of (1) to (7) above, the fluctuating heat from the outside is solar heat obtained by concentrating sunlight.

According to the configuration described in (8) above, the fuel flow rate supplied to the boiler (10) can be appropriately controlled even in the boiler (10) that utilizes solar heat obtained by concentrating sunlight.

(9) A boiler system (1) according to an embodiment of the present disclosure is
a boiler control device (100) according to any one of (1) to (8) above;
a heat exchanger (83) for transferring heat from a heat medium circulation channel (L6) for circulating a heat medium that receives fluctuating heat from the outside to the water supply;
A boiler including economizers (46, 47), a primary superheater (43) and a secondary superheater (42), and generating steam by heating feed water heat-exchanged with the heat medium by combustion of fuel. (10) and
Prepare.

According to the configuration described in (9) above, there is provided a boiler system (1) capable of more appropriately controlling the fuel flow rate in response to fluctuations in the amount of heat received from the outside.

(10) The power plant (2) according to an embodiment of the present disclosure is
The boiler system (1) according to (9) above;
a steam turbine (61) rotationally driven by the steam generated by the boiler system (1);
a generator (3) that is connected to the steam turbine (61) and generates power according to the rotation of the steam turbine (61);
Prepare.

According to the configuration described in (10) above, there is provided a power plant (2) that can more appropriately control the fuel flow rate in response to fluctuations in the amount of heat received from fluctuating heat from the outside.

(11) A boiler control method according to an embodiment of the present disclosure includes:
A control method for a boiler that generates steam from feed water, comprising:
A step of acquiring a first control signal for generating a fuel flow rate of fuel supplied to the boiler based on a base fuel flow rate signal generated based on the output target command and a third control signal according to the boiler load condition;
a step of acquiring heat-receiving amount information about the amount of heat received that varies from the outside;
a step of converting the received heat amount indicated by the acquired received heat amount information into the fuel flow rate and acquiring a correction signal for correcting the first control signal;
outputting a fuel flow rate command for controlling the fuel flow rate based on the first control signal and the correction signal to which a delay element is added;
Prepare.

According to the method described in (11) above, it is possible to control the operation conditions of the boiler (10), and more appropriately respond to fluctuations in the amount of heat received from fluctuating heat from the outside. It becomes possible to control the fuel flow rate.

1 boiler system 2 power plant 3 power generator 10 coal-fired boiler (boiler)
11 furnace 12 combustion device 13 flue 21, 22, 23, 24, 25 combustion burner 26, 27, 28, 29, 30 pulverized coal supply pipe 31, 32, 33, 34, 35 pulverizer 36 wind box 37 air duct 38 Forced draft fan (FDF)
41 Tertiary superheater (heat exchanger)
42 secondary superheater (heat exchanger)
43 Primary superheater (heat exchanger)
44 second reheater (heat exchanger)
45 first reheater (heat exchanger)
46 second economizer (heat exchanger)
47 1st economizer (heat exchanger)
48 gas duct 49 air heater (air preheater)
50 denitrification device 51 dust treatment device 52 induced draft fan (IDF)
53 Chimney 55 Bypass passage 56 Damper 60 Combustion gas passage 61 Steam turbine 62 High pressure turbine 63 Low pressure turbine 64 Condenser 65 Inlet header 66 Feed water pump 67 Intermediate header 68 Outlet header 69 Steam drum (steam water separator)
70 inlet header 72 outlet header 81 heat receiving section 82 circulation pump 83 heat exchanger 100 boiler control device 110 information acquisition section 120 first control signal acquisition section 121, 123, 129, 145, 163, 171, 172 comparator 122, 178 Adders 124, 125, 126, 164, 165, 166, 176 Function generators 127, 128, 167, 168, 169 Multiplier 130 Heat received information acquisition unit 140 Correction signal acquisition unit 150 Fuel flow command unit 160 Correction unit 170 Open Temperature control unit 173 PI control unit 174 P control unit 175, 177 Switching unit 179 Switch L1, L2 Water supply lines L3, L4, L5 Steam line L6 Heat medium circulation flow path

Claims (11)

A control device for a boiler that generates steam from feed water,
A first control signal for acquiring a first control signal for generating a fuel flow rate of fuel to be supplied to the boiler based on a base fuel flow rate signal generated based on the output target command and a third control signal according to the boiler load condition an acquisition unit;
a received heat amount information acquisition unit configured to acquire received heat amount information related to a fluctuating received heat amount from the outside;
a correction signal acquisition unit configured to convert the received heat amount indicated by the received heat amount information acquired by the received heat amount information acquisition unit into the fuel flow rate and acquire a correction signal for correcting the first control signal; ,
a fuel flow rate command unit configured to output a fuel flow rate command for controlling the fuel flow rate based on the first control signal and the correction signal to which a delay element is added;
A boiler control device comprising 2. The boiler control device according to claim 1, wherein the lag element is a first-order lag element having a time constant of change in outlet feedwater temperature of the economizer with respect to change in the received heat amount. 3. The first control signal acquisition unit generates the first control signal based on the base fuel flow rate signal and a second control signal generated based on one or more steam temperature deviations. The boiler control device according to . The first control signal acquisition unit, when the actual measurement value of the boiler load, the change rate of the boiler load, and the change width of the boiler load satisfy predetermined conditions, the fuel flow rate is higher than when the predetermined conditions are not satisfied. 4. The boiler control device according to claim 3, further comprising a correcting section for correcting the third control signal so as to reduce the . 5. The boiler control device according to claim 4, wherein the correction unit determines the decrease amount of the fuel flow rate in correcting the third control signal, based on the received heat amount indicated by the received heat amount information. An opening degree control unit for controlling the opening degree of a damper provided in a bypass flow path for bypassing the economizer,
The opening controller controls the damper based on the difference between the outlet feed water temperature of the economizer and the saturated steam temperature and the rate of decrease of the difference between the outlet feed water temperature of the economizer and the saturated steam temperature. 6. The boiler control device according to any one of claims 1 to 5, wherein the opening of the boiler is controlled. The received heat amount information acquisition unit calculates the received heat amount based on the temperature difference and the flow rate of the water supply at positions before and after a position where heat is transferred from the heat medium that receives the fluctuating heat from the outside to the water supply. The boiler control device according to any one of claims 1 to 6. The boiler control device according to any one of claims 1 to 7, wherein the fluctuating heat from the outside is solar heat obtained by concentrating sunlight. A boiler control device according to any one of claims 1 to 8;
a heat exchanger that transfers heat from a heat medium circulation passage for circulating a heat medium that receives fluctuating heat from the outside to the water supply;
a boiler that includes an economizer, a primary superheater and a secondary superheater, and generates steam by heating feed water that has undergone heat exchange with the heat medium by combustion of fuel;
Boiler system with A boiler system according to claim 9;
a steam turbine rotationally driven by the steam generated by the boiler system;
a generator connected to the steam turbine for generating power according to rotation of the steam turbine;
A power plant with a A control method for a boiler that generates steam from feed water, comprising:
A step of acquiring a first control signal for generating a fuel flow rate of fuel supplied to the boiler based on a base fuel flow rate signal generated based on the output target command and a third control signal according to the boiler load condition;
a step of acquiring heat-receiving amount information about the amount of heat received that varies from the outside;
a step of converting the received heat amount indicated by the acquired received heat amount information into the fuel flow rate and acquiring a correction signal for correcting the first control signal;
outputting a fuel flow rate command for controlling the fuel flow rate based on the first control signal and the correction signal to which a delay element is added;
A control method for a boiler comprising

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