Control device for boiler, boiler system including the same, control method for boiler and control program for boiler

Abstract

To secure stability of feedback control and improve responsiveness to fluctuation of a process value compared to when a primary delay element is used.SOLUTION: A control device 200 for a boiler that performs feedback control includes: an information acquisition section 210 that acquires boiler operation information including a process value that is input information; a movement average value calculation section 211 that calculates a movement average value that is a movement average of the process value for a predetermined period; an operation amount calculation section 213 that calculates an operation amount on the basis of the movement average value calculated by the movement average value calculation section; and an execution section 214 that executes control of the boiler by using the operation amount calculated by the operation amount calculation section.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a boiler control device, a boiler system including the same, a boiler control method, and a boiler control program. [Background technology]

[0002] Large boilers, such as power generation boilers, have a hollow furnace installed vertically, with multiple burners arranged circumferentially around the furnace wall. Large boilers also have a flue connected vertically above the furnace, with a heat exchanger for generating steam located in the flue. The burner injects a mixture of fuel and air (oxidizing gas) into the furnace, forming a flame, generating combustion gas that flows down the flue. A heat exchanger is installed in the area where the combustion gas flows, and superheated steam is generated by heating water or steam flowing through the heat transfer tubes that make up the heat exchanger.

[0003] As disclosed in Patent Documents 1 and 2, feedback control is sometimes used to control boilers. Generally, the temperature and pressure of the boiler are monitored using various sensors corresponding to the monitored objects, and feedback is provided to the boiler's control system based on the detection results of the various sensors. The control system then compares the target value with the current state and adjusts the manipulated variable so that the deviation obtained by the comparison approaches zero. In this way, feedback control can be used to operate the boiler stably. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-245604 [Patent Document 2] Patent Publication No. 2021-21554 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the amount of change in the process value per unit time is large, in other words, when the rate of change of the process value is large, hunting may occur depending on the degree of influence of the manipulated variable. In such cases, a first-order lag circuit (LAG) is added to the feedback signal to mitigate (reduce) the deviation from the target value, and feedback control is performed. However, in this case, while the control deviation becomes smaller and controllability improves as the set time of the first-order lag circuit is extended, it is not possible to suppress transient fluctuations in the process value, which is the basis for the control before the first-order lag element is added, and stable control cannot be achieved.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a boiler control device that ensures the stability of feedback control and improves responsiveness to fluctuations in process values ​​compared to when a first-order lag element is used, a boiler system equipped with the same, a boiler control method, and a boiler control program. [Means for solving the problem]

[0007] A boiler control device according to one embodiment of the present disclosure is a boiler control device that performs feedback control and includes an information acquisition unit that acquires boiler operation information including process values ​​that are input information, a moving average value calculation unit that calculates a moving average value that is a moving average of the process values ​​over a predetermined period of time, an operation quantity calculation unit that calculates an operation quantity based on the moving average value calculated by the moving average value calculation unit, and an execution unit that executes boiler control using the operation quantity calculated by the operation quantity calculation unit.

[0008] A boiler system according to one aspect of the present disclosure includes a control device for the boiler, a heat exchanger provided in a combustion gas flow path through which combustion gas flows to recover heat from the combustion gas, and a boiler that burns pulverized fuel made from pulverized solid fuel using a burner and exchanges the heat generated by this combustion with feedwater or steam to generate superheated steam.

[0009] A boiler control method according to one aspect of the present disclosure is a boiler control method that performs feedback control, and includes an information acquisition process for acquiring boiler operation information including process values ​​that are input information; a moving average value calculation process for calculating a moving average value that is a moving average of the process values ​​over a predetermined period of time; an operation quantity calculation process for calculating an operation quantity based on the moving average value calculated in the moving average value calculation process; and an execution process for executing boiler control using the operation quantity calculated in the operation quantity calculation process.

[0010] A boiler control method according to one aspect of the present disclosure is a boiler control method that performs feedback control, and includes a first-order lag element calculation step that calculates a first-order lag element when it is assumed that the first-order lag element is added to a process value over a predetermined period of time; a moving average value calculation step that calculates a moving average value that is a moving average of the process values ​​over the predetermined period of time; a manipulated variable calculation step that calculates a manipulated variable using either the first-order lag element calculated in the first-order lag element calculation step or the moving average value calculated in the moving average value calculation step; and a change rate determination step that determines whether the rate of change of the process value over the predetermined period of time is greater than a predetermined value, wherein in the manipulated variable calculation step, the manipulated variable is calculated using the calculation result of the moving average value calculation step instead of the calculation result of the first-order lag element calculation step, depending on the determination result of the change rate determination step.

[0011] A boiler control program according to one aspect of the present disclosure is a boiler control program that performs feedback control to calculate an operating variable in plant control, and causes a computer to execute the following: an information acquisition process that acquires boiler operation information including a process value that is input information in the feedback control; a moving average value calculation process that calculates a moving average value that is a moving average of the process value over a predetermined period based on the boiler operation information in the feedback control in order to bring the deviation between the target output value and the current process value closer to zero; an operating variable calculation process that calculates the operating variable based on the moving average value calculated in the moving average value calculation process; and an execution process that executes boiler control using the operating variable calculated in the operating variable calculation process. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a boiler control device, a boiler system equipped with the same, a boiler control method, and a boiler control program that can ensure the stability of feedback control and improve responsiveness to fluctuations in process values ​​compared to when a first-order lag element is used. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram illustrating a coal-fired boiler according to an embodiment. [Figure 2] 1 is a schematic diagram showing a steam, condensate, and feedwater system in a coal-fired boiler (once-through boiler) according to one embodiment. FIG. [Figure 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a boiler control device. [Figure 4] FIG. 2 is a functional configuration diagram showing an example of functions of the boiler control device according to the present embodiment. [Figure 5] FIG. 2 is a circuit diagram showing a configuration related to fuel flow rate control of the boiler control device according to the embodiment. [Figure 6] FIG. 10 is a diagram illustrating the responsiveness of feedback control using a first-order lag element. [Figure 7]FIG. 10 is a diagram illustrating the responsiveness of feedback control using a moving average. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to this embodiment, and when there are multiple embodiments, it also includes configurations that combine the embodiments. In the following description, "up" and "upper" refer to the upper side in the vertical direction, and "lower" and "lower" refer to the lower side in the vertical direction, and the vertical direction is not precise and may include errors.

[0015] FIG. 1 is a schematic diagram showing the configuration of a boiler using solid fuel as the main fuel according to this embodiment.

[0016] The boiler 10 of this embodiment is a boiler that can generate superheated steam by burning pulverized fuel made by pulverizing solid fuel with a burner and exchanging the heat generated by this combustion with feedwater or steam. Biomass fuel, coal, etc. are used as solid fuel.

[0017] The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylindrical shape and is installed vertically. The furnace wall 101 that forms the inner wall surface of the furnace 11 is composed of a plurality of heat transfer tubes and fins that connect the heat transfer tubes together, and recovers the heat generated by the combustion of pulverized fuel by heat exchange with water and steam circulating inside the heat transfer tubes, while suppressing the temperature rise of the furnace wall 101.

[0018] The combustion device 20 is installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter, may be collectively referred to as "burners 21") attached to the furnace wall 101. The burners 21 are arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of the rectangular furnace 11), and are arranged in multiple rows along the vertical direction as one set. Note that, for convenience of illustration, FIG. 1 shows only two burners from one set, and each set is denoted by the reference numerals 21A, 21B, 21C, 21D, 21E, and 21F. The shape of the furnace, the number of burner rows, the number of burners in one row, the arrangement of the burners, and the like are not limited to this embodiment.

[0019] Burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, sometimes collectively referred to as "mills 31") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (hereinafter, sometimes collectively referred to as "pulverized fuel supply pipes 22"). Mill 31 is, for example, a vertical roller mill having a pulverizing table (not shown) supported therein so as to be rotatable, and a plurality of pulverizing rollers (not shown) supported above the pulverizing table so as to be rotatable in conjunction with the rotation of the pulverizing table. The solid fuel pulverized by the cooperation of the pulverizing rollers and the pulverizing table is transported to a classifier (not shown) provided in mill 31 by primary air (carrier gas, oxidizing gas) supplied to mill 31. The classifier separates the pulverized fuel into pulverized fuel having a particle size smaller than that suitable for combustion in the burner 21 and coarse pulverized fuel having a particle size larger than that. The pulverized fuel passes through the classifier and is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table inside the mill 31 under its own weight and is re-ground.

[0020] An air register 23 is provided outside the furnace 11 at the installation position of the burner 21, and one end of an air duct 24 is connected to the air register 23. A forced draft fan (FDF) 32 is connected to the other end of the air duct 24. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24 (details will be described later), and is supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas) and introduced into the furnace 11.

[0021] The combustion gas passage 12 is connected to the vertical upper part of the furnace 11. The combustion gas passage 12 is provided with superheaters 102A, 102B, and 102C (hereinafter sometimes collectively referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter sometimes collectively referred to as "reheaters 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and feedwater or steam flowing inside each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to those shown in FIG. 1.

[0022] A flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas whose heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the air duct 24, and heat is exchanged between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13, heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, thereby recovering further heat from the combustion gas after heat exchange with water and steam.

[0023] Furthermore, a denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitration device 43 supplies a reducing agent, such as ammonia or urea water, which has the effect of reducing nitrogen oxides, to the combustion gas flowing through the flue 13, and promotes the reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent by the catalytic action of a denitration catalyst provided in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas. A gas duct 41 is connected to the flue 13 downstream of the air preheater 42. The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, that removes ash and the like from the combustion gas, and a desulfurization equipment 46 that removes sulfur oxides, as well as an induced draft fan (IDF) 45 that guides the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas that has been treated in the environmental equipment is discharged to the outside of the system as exhaust gas.

[0024] In the boiler 10, when the multiple mills 31 are driven, pulverized and classified pulverized fuel is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. Secondary air heated by the air preheater 42 is supplied to the burner 21 from the air duct 24 via the wind box 23. The burner 21 blows a pulverized fuel mixture, which is a mixture of pulverized fuel and primary air, into the furnace 11, and also blows secondary air into the furnace 11. The pulverized fuel mixture blown into the furnace 11 ignites and reacts with the secondary air to form a flame. A flame is formed in the lower region of the furnace 11, and high-temperature combustion gas rises within the furnace 11 and flows into the combustion gas passage 12. In this embodiment, air is used as the oxidizing gas (primary air, secondary air). However, the oxidizing gas may have a higher or lower oxygen content than air. By adjusting the ratio of the oxygen content to the amount of fuel supplied within an appropriate range, stable combustion in the furnace 11 is achieved.

[0025] Additionally, above the mounting position of the burners 21 in the furnace 11, a plurality of additional air ports (AA ports) 25 are provided for supplying additional air for combustion (AA) into the furnace 11. The additional air ports 25 are connected to the ends of additional air ducts (AA ducts) 26 branching off from the air duct 24, and a portion of the air supplied from the forced draft fan 32 can be supplied to the additional air ports 25 via the additional air ducts 26 as additional air for combustion.

[0026] In region A (corresponding to the installation range of the wind box 23 in the height direction) inside the furnace 11 shown in Fig. 1, a flame is formed by combustion of a mixture of primary air and pulverized fuel with secondary air. Here, the air ratio in region A is set to be 1 or less, specifically, the amount of air supplied to the burner 21 (the total amount of primary air and secondary air) is set to be less than the theoretical amount of air relative to the amount of fuel supplied to the burner 21. By doing so, regions A and B (regions between the top of the burner 21 and the bottom of the additional air port 25) inside the furnace 11 become reducing atmospheres, and nitrogen oxides (NOx) generated by combustion are reduced inside the furnace 11. Thereafter, in region C (region above the bottom of the additional air port 25), additional combustion air is supplied from the additional air port 25 to the combustion gas in which NOx has been reduced, completing the combustion. However, the amount of NOx generated is reduced by the reduction effect in regions A and B.

[0027] The combustion gas that has flowed into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and an economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in a denitration device 43, and the gas exchanges heat with primary air and secondary air in an air preheater 42, and is then discharged into the gas duct 41, where ash and the like are removed in a dust collector 44, and sulfur oxides are removed in a desulfurization device 46, and the gas is then discharged to the outside of the system from a chimney 47. Note that the arrangement of the heat exchangers in the combustion gas passage 12 and the arrangement of the devices from the flue 13 to the gas duct 41 with respect to the combustion gas flow do not necessarily have to be in the order described above.

[0028] Next, a detailed description will be given of the heat exchangers, namely, the superheater 102, the reheater 103, and the economizer 104, which are provided in the combustion gas passage 12. FIG. 2 is a schematic diagram showing the heat exchangers provided in the coal-fired boiler 10. Note that Figure 1 does not accurately show the positions of the heat exchangers (superheaters 102A, 102B, 102C, reheaters 103A, 103B, and economizer 104) in the combustion gas passage 12, and the arrangement order of the heat exchangers relative to the combustion gas flow is not limited to that shown in Figure 1.

[0029] As shown in Figure 2, the power plant 1 of this embodiment includes a heat exchanger provided in the boiler 10, a steam turbine 111 that is rotationally driven by steam generated in the boiler 10, and a generator 113 that is connected to the steam turbine 111 and generates electricity using the rotational force of the steam turbine 111.

[0030] The steam turbine 111 is composed of, for example, a high-pressure turbine 111A, an intermediate-pressure turbine 111B, and a low-pressure turbine 111C. Steam heated by a superheater 102 of the boiler 10 drives the high-pressure turbine 111A, is reheated by a reheater 103 of the boiler 10, and drives the intermediate-pressure turbine 111B and the low-pressure turbine 111C. A condenser 112 is connected to the low-pressure turbine 111C, and the steam that drives the low-pressure turbine 111C is condensed into condensate by heat exchange with cooling water (e.g., seawater or river water) in the condenser 112. The condenser 112 is connected to the economizer 104 via a feedwater line L1. The feedwater line L1 is provided with, for example, a condensate pump (CP) 121, a low-pressure feedwater heater 122, a boiler feedwater pump (BFP) 123, and a high-pressure feedwater heater 124. A portion of the steam that drives the steam turbine 111 is extracted and supplied to the low-pressure feedwater heater 122 and the high-pressure feedwater heater 124 as a heat source via an extraction line (not shown), and the feedwater supplied to the economizer 104 is heated.

[0031] For example, a case will be described in which the boiler 10 is a once-through boiler. The economizer 104 is connected to heat transfer tubes that constitute the furnace wall 101. The feedwater heated by the economizer 104 is heated by radiation from the flame in the furnace 11 as it passes through the heat transfer tubes that constitute the furnace wall 101, and is then led to the steam separator 125. The steam separated in the steam separator 125 is supplied to the superheater 102, and the drain water separated in the steam separator 125 flows into the steam separator drain tank 126 and is led to the condenser 112 via the drain water line L2.

[0032] Furthermore, during startup or low-load operation of the once-through boiler, the feedwater supplied from the economizer 104 may not all evaporate as it passes through the heat transfer tubes that make up the furnace wall 101, resulting in an operating state (wet operating state) in which a water level exists in the steam separator 125. In this wet operating state, the drain water separated in the steam separator 125 and discharged to the steam separator drain tank 126 may be circulated and supplied from the economizer 104 to the heat transfer tubes that make up the furnace wall 101 by using a boiler circulation pump (BCP) 127 to merge with the feedwater line L1 via a circulation line L6.

[0033] When the combustion gas flows through the combustion gas passage 12, heat of the combustion gas is recovered by the superheater 102, the reheater 103, and the economizer 104. Meanwhile, feedwater supplied from a boiler feed pump (BFP) 123 is preheated by the economizer 104, and then heated to become steam as it passes through the heat transfer tubes that make up the furnace wall 101, and is then guided to a steam separator 125. The steam separated in the steam separator 125 is introduced into the first superheater 102A, the second superheater 102B, and the third superheater 102C, where it is superheated by the combustion gas. The superheated steam generated in the superheater 102 is supplied to the high-pressure turbine 111A via a steam line L3, and rotates and drives the high-pressure turbine 111A. The steam discharged from the high-pressure turbine 111A is introduced into the first reheater 103A and the second reheater 103B, where it is superheated again. The re-superheated steam is supplied via steam line L5 to the low-pressure turbine 111C via the intermediate-pressure turbine 111B, and rotates the intermediate-pressure turbine 111B and the low-pressure turbine 111C. The rotating shaft of the steam turbine 111 rotates the generator 113, generating electricity. The steam discharged from the low-pressure turbine 111C is cooled in the condenser 112 to become condensed water, and is sent again to the economizer 104 via the water supply line L1.

[0034] The superheater 102 and the reheater 103 may be provided with means for controlling the temperature of the steam superheated in each heat exchanger (hereinafter, the temperature of the superheated steam at the outlet of the third superheater 102C is referred to as the "main steam temperature," and the temperature of the superheated steam at the outlet of the second reheater 103B is referred to as the "reheated steam temperature"). For example, a superheater spray valve (not shown) or a reheater spray valve (not shown) may be provided to control the steam temperature by adjusting the amount of water mixed and injected into the superheated steam (hereinafter, the water injected to control the main steam temperature is referred to as the "superheater spray water," and the water injected to control the reheated steam temperature is referred to as the "reheater spray water"). The superheater spray water and the reheater spray water are supplied, for example, by branching a portion of the feedwater to the boiler 10 from the outlet of the boiler feedwater pump 123. The position where the superheater spray water is mixed and injected is not limited to the outlet of the third superheater 102C, and may be any position where the main steam temperature can be controlled, for example, it may be installed at any position between the outlet of the steam separator 125 and the inlet of the high-pressure turbine 111A. Similarly, the position where the reheater spray water is mixed and injected is not limited to the outlet of the second reheater 103B, and may be any position where the reheat steam temperature can be controlled, for example, it may be installed at any position between the outlet of the high-pressure turbine 111A and the inlet of the intermediate-pressure turbine 111B.

[0035] In addition, a soot blower (ash removal device) (not shown) may be disposed in the combustion gas passage 12 in the gaps between the heat transfer tubes constituting each heat exchanger, such as the superheater 102, reheater 103, and economizer 104, or in the gaps between each heat exchanger. The soot blower is disposed extending in a direction approximately perpendicular to the wall surface of the combustion gas passage 12. The soot blower is an injection device that injects steam (gas) in a direction perpendicular to the axial direction, with the axial direction being perpendicular to the wall surface of the combustion gas passage 12, and that can also change the injection direction. Steam injected from the soot blower toward heat exchangers, such as the superheater 102, reheater 103, and economizer 104, removes combustion ash that has adhered to and accumulated on the surfaces of the heat transfer tubes constituting the heat exchangers, thereby suppressing a decrease in the heat exchange efficiency of the heat transfer tubes.

[0036] Next, the boiler control device 200 according to this embodiment will be described. Fig. 3 is a diagram showing an example of the hardware configuration of a boiler control device 200. As shown in Fig. 3, the boiler control device 200 is a computer, and includes, for example, a CPU (Central Processing Unit: processor) 201, a main memory 202, a secondary storage 203, a communication interface 204, etc. The boiler control device 200 may also include an input device 205 that accepts input from a user, a display 206, etc. These components are connected via, for example, a bus 208.

[0037] The main memory device 202 is composed of writable memory such as cache memory and RAM (Random Access Memory), and is used as a working area for reading out programs executed by the CPU 201 and writing data processed by the programs. The secondary storage device 203 is a non-transitory computer-readable storage medium. Examples of the secondary storage device 203 include a magnetic disk such as a hard disk drive (HDD), a magneto-optical disk, a CD-ROM, a DVD-ROM, and a semiconductor memory such as a solid state drive (SSD).

[0038] In conventional boiler control, a method of suppressing hunting in feedback control is known in which a first-order lag circuit (LAG) is added to the feedback signal. However, in control systems where the fluctuation of a process value over a given period is transient, even using a first-order lag element cannot suppress the transient fluctuation of the underlying process value, making it difficult to achieve stable control. For this reason, the inventors have investigated improving the responsiveness of feedback control by calculating a moving average value instead of using a first-order lag element. Note that the process value is specifically a quantity that is controlled to stabilize the operation of a plant, such as temperature, pressure, flow rate, frequency, etc.

[0039] 4 is a functional configuration diagram showing an example of functions possessed by the boiler control device 200 according to this embodiment. The boiler control device 200 performs feedback control using information acquired by various sensors in order to operate the boiler stably. Specifically, as shown in FIG. 4, the boiler control device 200 includes an information acquisition unit 210, a moving average value calculation unit 211, an intermediate calculation unit 212, an operation amount calculation unit 213, an execution unit 214, a rate of change determination unit 215, an operation determination unit 216, and a first-order lag element calculation unit 220. The boiler control device 200 is also electrically connected to an alarm unit 217.

[0040] A series of processes for realizing the various functions described below is stored in the secondary storage device 203 (see FIG. 3) in the form of a program (e.g., a boiler control program), for example, and the CPU 201 reads this program into the main storage device 202 and executes information processing and arithmetic processing to realize the various functions. Note that the program may be pre-installed in the secondary storage device 203, provided in a state stored in another computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0041] The information acquisition unit 210 acquires boiler operation information, which is input information for feedback control. The information acquisition unit 210 is, for example, various sensors that detect the boiler operation information. The operation information includes, for example, information on the output of the generator 113, information on the pressure of steam flowing into the inlet of the steam turbine 111 (main steam pressure at the steam turbine inlet), information on the feedwater flow rate, and information on the boiler load (the ratio of the amount of steam generated to the rated steam amount of the boiler system). The operation information acquired by the information acquisition unit 210 may be sequentially stored in the secondary storage device 203. Without being limited to this example, the information acquisition unit 210 may acquire various information necessary for boiler control, such as a generator output target command, one or more steam temperature deviations, information regarding the boiler load (current boiler load) and the target boiler load, and sensor information necessary for calculating the amount of received heat (e.g., measured values ​​such as the pressure, flow rate, and temperature difference of the water supply).

[0042] In feedback control, the moving average value calculation unit 211 calculates a moving average of the feedback signal over a predetermined period based on boiler operation information in order to bring the deviation between the output target value and the current process value closer to zero. The moving average value calculation unit 211 calculates the moving average value of the process value using, for example, the process value acquired by the information acquisition unit 210 and the past process value stored in the secondary storage device 203. When the moving average value calculation unit 211 calculates the moving average value, the sampling period and the number of samples may be set by user input according to the rate of change of the process value. The moving average value calculation unit 211 includes, for example, an adder, a divider, a delay device, etc., and calculates the moving average value of a plurality of input values.

[0043] The intermediate calculation unit 212 calculates the deviation between the target value in feedback control for each value of the boiler load fluctuation command value and the moving average value calculated by the moving average value calculation unit 211. The intermediate calculation unit 212 includes, for example, a function generator, a comparator, an integrator, and an adder, and outputs the target value of the output in feedback control.

[0044] The manipulated variable calculation unit 213 calculates a manipulated variable based on the moving average value calculated by the moving average value calculation unit 211. The manipulated variable calculation unit 213 includes, for example, a PI (Proportional-Integral) controller, and outputs a manipulated variable for bringing the deviation between the target value of the output and the current process value closer to zero.

[0045] The execution unit 214 executes boiler control using the manipulated variable calculated by the manipulated variable calculation unit 213. The execution unit 214 changes the output of each component involved in boiler control, for example, based on the manipulated variable calculated by the manipulated variable calculation unit 213.

[0046] The change rate determination unit 215 determines whether the rate of change of the process value over a predetermined period is greater than a predetermined value. When the change rate determination unit 215 determines that the rate of change of the process value is greater than the predetermined value, the control device 200 may switch the control content of the feedback control so that the moving average value calculation unit 211 calculates a moving average value of the process value.

[0047] The operation determination unit 216 determines whether the moving average value is equal to or greater than a predetermined lower limit value during a predetermined period of time during feedback control. For example, the operation determination unit 216 determines whether the moving average value of the process value at a point in time when a predetermined period has elapsed since the start of feedback control is close to the current process value. Furthermore, when the operation determining unit 216 determines that the moving average value of the process value is not close to the current process value, it may determine that an operation abnormality has occurred and output the determination result to the warning unit 217 .

[0048] The alarm unit 217 issues an alarm in accordance with the determination result of the operation determination unit 216. For example, the alarm unit 217 is capable of electrically communicating with the control device 200 and can receive the determination result of the operation determination unit 216. Furthermore, without being limited to this, the alarm unit 217 may also prompt the plant manager to temporarily suspend the operation of the boiler in accordance with the determination result of the operation determination unit 216.

[0049] The first-order lag element calculation unit 220 calculates a first-order lag element when it is assumed that a first-order lag element is added to a process value signal for a predetermined period in order to bring the deviation between a target value and a current process value closer to zero in feedback control.

[0050] (Feedback control in boiler control) FIG. 5 is a circuit diagram related to feedback control performed by a boiler control device according to an embodiment. Hereinafter, a flow of calculating a manipulated variable using a process value as a feedback signal will be described with reference to FIG. 5. In FIG. 5, the load request command value, generator output, turbine inlet main steam pressure, and main feedwater flow rate are acquired by an information acquisition unit 210. Moving average circuits ave1-ave3 are configured by adders, dividers, delay devices, etc., provided in a moving average value calculation unit 211, and are circuits used by the moving average value calculation unit 211 to calculate moving average values ​​of the process values. Comparators com1-com3, function setting units F1 and F2, integrator I1, and adder A1 are configured by calculators provided in an intermediate calculation unit 212, and the intermediate calculation unit 212 is configured to output a target value of output in feedback control. PI controllers PI1 and PI2 are controllers used by a manipulated variable calculation unit 213 to calculate a manipulated variable for bringing the deviation between the target value of output and the current process value closer to zero.

[0051] (Feedback control of steam turbine rotational frequency) First, feedback control in the case where the rotational frequency of the steam turbine 111 that contributes to the output of the generator is used as the process value will be described. In the feedback control related to the rotational frequency of the steam turbine 111, first, the information acquisition unit 210 acquires a load request command value (target value) of the control system. Here, the load request command value is, for example, a target value of the rotational frequency of the steam turbine 111. Furthermore, the information acquisition unit 210 acquires information related to the output of the generator. The information related to the output of the generator is, for example, the power output of the generator, the ratio to the rated output of the generator, the rotational frequency of the steam turbine 111 connected to the generator, etc.

[0052] The load request command value may be a value calculated based on boiler operation information acquired by the information acquisition unit 210. The load request command value is, for example, a generator output target command, one or more steam temperature deviations, information on the boiler load (current boiler load) and the target boiler load, and sensor information required for calculating the amount of received heat (for example, measured values ​​of feedwater pressure, flow rate, temperature difference, etc.). The load request command value may be determined appropriately using a known calculation method, and a detailed description thereof will be omitted.

[0053] The moving average value calculation unit 211 uses the rotation frequency of the steam turbine 111 acquired by the information acquisition unit 210 to calculate a moving average value of the rotation frequency of the steam turbine 111 for a predetermined period. For example, the information acquisition unit 210 samples the rotational frequency of the steam turbine 111 at a sampling period of 200 msec. Then, each sample acquired by the information acquisition unit 210 is stored in the secondary storage device 203 one by one.

[0054] The moving average value calculation unit 211 calculates a moving average value of the rotational frequency of the steam turbine 111 using each sample stored in the secondary storage device 203. More specifically, first, a moving average circuit ave1, which is configured with an adder, a divider, a delay unit, etc., provided in the moving average value calculation unit 211, calculates the sum of the current rotational frequency of the steam turbine 111 and a predetermined number of past rotational frequencies of the steam turbine 111 determined according to the number of samples, using Equation (1) described below. Next, the moving average circuit ave1 calculates a moving average value of the rotational frequency of the steam turbine 111 by dividing the calculated sum of the rotational frequencies of the steam turbine 111 by the number of samples. Then, the moving average circuit ave1 outputs the calculated moving average value of the rotational frequency of the steam turbine 111 to a comparator comp1. Note that the number of samples is set appropriately, for example, to 10 samples. The moving average value is specifically calculated using the following Equation (1). In the formula (1), N is the number of samples, X is the current rotation frequency of the steam turbine 111, and V1 to V N―1is the past rotation frequency of the steam turbine 111, and Y is the moving average value.

[0055]

number

[0056] Next, the load request command value acquired by the information acquisition unit 210 and the moving average value of the rotational frequency of the steam turbine 111 calculated by the moving average value calculation unit 211 are input to the comparator com1. The comparator com1 outputs the deviation between the load request command value and the moving average value of the rotational frequency of the steam turbine 111 to the PI controller PI1.

[0057] The PI controller PI1 performs proportional-integral control (PI control) based on the output of the comparator com1 and the moving average value calculated by the moving average value calculation unit 211. Then, the PI controller PI1 outputs a manipulated variable to the governor to execute boiler control corresponding to the load request command value obtained by the PI control. The manipulated variable output to the governor is, for example, a fuel flow command value for controlling the fuel flow rate of fuel supplied to the boiler. However, the manipulated variable output to the governor may also be a command value related to the opening of a control valve of the governor. Then, the execution unit 214 executes boiler control based on the manipulated variable output from the PI controller PI1.

[0058] As described above, by using the moving average value of the rotational frequency of the steam turbine 111 as the input value of the PI control in the feedback control, the manipulated variable is calculated using the moving average value of the process value (feedback signal), which ensures the stability of the feedback control and improves the responsiveness to fluctuations in the process value compared to when a first-order lag element is used.

[0059] (Feedback control of main water supply flow rate) 5, in addition to the feedback control related to the generator output, feedback control is also performed in which the adjustment amount of the main feedwater flow rate is output. In this case, each process value related to the inlet main steam pressure of the steam turbine 111 and the main feedwater flow rate serves as a feedback signal.

[0060] 5, the information acquisition unit 210 acquires a load request command value (target value) of the control system. Here, the load request command value is, for example, a target value of the inlet main steam pressure of the steam turbine 111. Furthermore, the information acquisition unit 210 acquires the inlet main steam pressure of the steam turbine 111.

[0061] The moving average value calculation unit 211 uses the inlet main steam pressure of the steam turbine 111 acquired by the information acquisition unit 210 to calculate a moving average value of the inlet main steam pressure of the steam turbine 111 for a predetermined period. For example, the information acquisition unit 210 samples the inlet main steam pressure of the steam turbine 111 at a sampling period of 200 msec. Then, each sample acquired by the information acquisition unit 210 is stored in the secondary storage device 203 one by one. The moving average value calculation unit 211 calculates a moving average value of the inlet main steam pressure of the steam turbine 111 using each sample stored in the secondary storage device 203. More specifically, first, the moving average circuit ave2, which is composed of an adder, a divider, a delay unit, etc., provided in the moving average value calculation unit 211, calculates the sum of the current inlet main steam pressure of the steam turbine 111 and a predetermined number of past inlet main steam pressures of the steam turbine 111, determined according to the number of samples, using the above formula (1). Furthermore, the moving average circuit ave2 calculates a moving average value of the inlet main steam pressure of the steam turbine 111 by dividing the calculated sum of the inlet main steam pressure of the steam turbine 111 by the number of samples. The moving average circuit ave2 then outputs the calculated moving average value of the inlet main steam pressure of the steam turbine 111 to the comparator comp2. The number of samples is set appropriately, for example, to 10 samples.

[0062] Meanwhile, the load request command value (target value) acquired by the information acquisition unit 210 is input to a function generator Fun1. A function is set in the function generator Fun1 to output a main steam pressure target value for calculating a deviation from the moving average value calculated by the moving average value calculation unit 211 based on the input load request command value. Then, the function generator Fun1 outputs the main steam pressure target value to a comparator com2.

[0063] The moving average value of the inlet main steam pressure of the steam turbine 111 calculated by the moving average value calculation unit 211 is input to the comparator com2. Then, the comparator com2 outputs the deviation between the main steam pressure target value output from the function generator Fun1 and the moving average value of the inlet main steam pressure of the steam turbine 111 calculated by the moving average value calculation unit 211. The deviation output from the comparator com2 is integrated by the integrator I1 to remove the steady-state deviation, and is input to the adder A1.

[0064] Adder A1 receives the main steam pressure deviation output from integrator I1 and the load request command value acquired by information acquisition unit 210, and outputs the sum to function generator Fun2. Function generator Fun2 is set with a function that outputs a main feedwater flow rate target value based on the output of adder A1. Function generator Fun2 then outputs the main feedwater flow rate target value to comparator com3.

[0065] Here, the moving average value calculation unit 211 calculates the moving average value of the inlet main steam pressure of the steam turbine 111, and also calculates the moving average value of the main feedwater flow rate by a similar method. The moving average value calculation unit 211 uses the main water feed flow rate acquired by the information acquisition unit 210 to calculate a moving average value of the main water feed flow rate for a predetermined period. For example, the information acquisition unit 210 samples the main water supply flow rate at a sampling period of 200 msec intervals. Each sample acquired by the information acquisition unit 210 is stored in the secondary storage device 203 one by one. The moving average value calculation unit 211 calculates the moving average value of the main water supply flow rate using each sample stored in the secondary storage device 203. More specifically, first, the moving average circuit ave3, which is composed of an adder, divider, delay unit, etc. provided in the moving average value calculation unit 211, calculates the sum of the current main water supply flow rate and a predetermined number of past main water supply flow rates determined according to the number of samples, using the above formula (1). Furthermore, the moving average circuit ave3 calculates the moving average value of the main water supply flow rate by dividing the calculated sum of the main water supply flow rates by the number of samples. The moving average circuit ave3 then outputs the calculated moving average value of the main water supply flow rate to the comparator comp3. The number of samples is set appropriately, for example, to 10 samples.

[0066] The moving average value of the main feedwater flow rate calculated by the moving average value calculation unit 211 is input to the comparator com3. The comparator com3 outputs the deviation between the main feedwater flow rate target value output from the function generator Fun1 and the moving average value of the main feedwater flow rate calculated by the moving average value calculation unit 211 to the PI controller PI2. The PI controller PI2 performs PI control based on the output of the comparator com3 and the moving average value of the main feedwater flow rate calculated by the moving average value calculation unit 211. Then, the PI controller PI2 outputs a manipulated variable to the governor to execute the main feedwater flow rate control in the boiler corresponding to the load request command value obtained by the PI control. Here, the manipulated variable output to the governor is, for example, a command value related to the opening of a control valve for controlling the feedwater flow rate of the boiler.

[0067] As described above, even when feedback control is performed using a process value other than the rotational frequency of the steam turbine 111, the stability of the feedback control can be ensured and the responsiveness to fluctuations in the process value can be improved compared to when a first-order lag element is used.

[0068] The sampling period and number of samples used to calculate the moving average value may be changed as appropriate depending on the tendency of fluctuations in the process value in each feedback control. For example, when dealing with a moving average value of a process value that fluctuates significantly even in a short period of time, it is preferable to set a high sampling frequency and a large number of samples. Note that setting the sampling frequency or number of samples excessively high may increase the calculation cost and cause delays in each process of the control device. For this reason, when the moving average value is calculated by the moving average value calculation unit 211, the sampling period and number of samples may be changed as appropriate depending on the tendency of fluctuations in the process value in each feedback control. For example, the number of samples may be set as appropriate between 2 and 10. Increasing the number of samples can provide the effect of smoothing noise. Reducing the number of samples can provide the effect of faster response to fluctuations in the process value.

[0069] Next, using Figures 6 and 7, the responsiveness of feedback control using a first-order lag element and feedback control using a moving average will be compared. Figure 6 is a diagram showing the responsiveness of feedback control using a first-order lag element. Figure 7 is a diagram showing the responsiveness of feedback control using a moving average. In Figures 6 and 7, the horizontal axis is time, the left vertical axis is the ratio between the governor control valve opening and the generator output, and the right vertical axis is frequency. The solid line is the governor control valve opening. The dashed line is the generator output. The dotted line is the rotational frequency of the steam turbine 111. In Figure 6, the two-dot chain line is the corrected rotational frequency obtained by adding a first-order lag element (10 seconds) to the rotational frequency of the steam turbine 111. In Figure 7, the two-dot chain line is the moving average value of the rotational frequency with a sampling period of 10 seconds.

[0070] According to Figure 6, the rotational frequency undergoes a step response during the 1-minute period from the start of control (0 minutes), then rises at a constant rate, reaches 51 Hz, and then drops at a constant rate. Furthermore, the rotational frequency after correction with a first-order lag element changes toward the target value at a slower rate than the rotational frequency after correction with a first-order lag element, and reaches the target value slower than the rotational frequency without a first-order lag element. The governor control valve aperture decreases in response to the rise in the rotational frequency after correction, and increases in response to the fall in the rotational frequency. Furthermore, the generator output changes with a delay relative to the change in the governor control valve aperture, corresponding to the aperture of the governor control valve.

[0071] Furthermore, in Figure 7, the changes in rotational frequency are the same as in Figure 6. The moving average value of the rotational frequency with a sampling period of 10 seconds has less time delay with respect to the rotational frequency than when a first-order lag element is added to the rotational frequency, indicating high responsiveness. This also improves the responsiveness of the governor control valve opening to the rotational frequency. Furthermore, because the generator output corresponds to the governor control valve opening, the generator output also follows changes in the rotational frequency.

[0072] Comparing Figures 6 and 7, when the rotation frequency after correction, in which a first-order lag element is added to the rotation frequency, is compared with the moving average value of the rotation frequency with a sampling period of 10 seconds, it can be seen that the moving average value of the rotation frequency with a sampling period of 10 seconds has better responsiveness to fluctuations in the rotation frequency than when a first-order lag element is used.

[0073] As described above, in feedback control, by calculating the moving average value of the process value and controlling the aperture of the governor control valve, it is possible to ensure the stability of feedback control and improve responsiveness to fluctuations in the process value, compared to when a first-order lag is used.

[0074] Furthermore, the feedback control using the moving average value of the process value is preferably applied to a process value that has a large rate of change (a large change in value even in a short period of time), such as when applied to feedback control relating to combustion gas pressure control or draft (exhaust gas pressure) control. As an example, when coal is used as fuel and burned in the furnace 11 of the boiler 10, the opening of a control valve is intermittently changed to maintain an appropriate fuel-to-air ratio in the furnace 11, thereby controlling the combustion state in the furnace 11, in order to maintain a favorable combustion state in the furnace 11. Furthermore, the pressure of the exhaust gas is controlled to a negative pressure to prevent ash produced by combustion from flowing out of the furnace 11. When controlling the opening of each control valve to control the combustion state in the furnace 11 in this way, it is preferable to control each control valve by feedback control using a moving average value and to set a short sampling period for calculating the moving average value of the process value.

[0075] Feedback control using the moving average value of the process value is also applied when the denitration device 43 denitrifies the combustion gas flowing through the flue 13. For example, the control device 200 measures the ammonia concentration using a concentration analyzer in the information acquisition unit 210 and performs feedback control on the ammonia concentration. In this case, the moving average value of the ammonia concentration is used to control the aperture of the ammonia injection valve through feedback control, thereby quickly converging the ammonia concentration to a target value. This makes it possible to control the amount of nitrogen oxide emissions and to prevent clogging and corrosion in equipment downstream of the denitration device 43 due to excessive ammonia supply. The number of samples may be appropriately set between 2 and 10, taking into consideration the stability and responsiveness of boiler control.

[0076] (Variation) The following describes a modified example in which the above-described feedback control is partially modified. Note that the same reference numerals are used to designate components common to the above-described embodiment, and a description thereof will be omitted. The following mainly describes components that are different.

[0077] (Variation 1) The following describes a modified example in which the above-described feedback control is partially modified. Note that configurations that are not specifically described are the same as those in the above-described embodiment. In this modification, the change rate determination unit 215 included in the control device 200 determines whether the rate of change of the process value over a predetermined period is greater than a predetermined value. If the change rate determination unit 215 determines that the rate of change of the process value is greater than the predetermined value, the control content of the feedback control is switched so that the moving average value calculation unit 211 calculates a moving average value of the process value. For example, if the change rate determination unit 215 determines that the rate of change of the process value is greater than the predetermined value, the change rate determination unit 215 may output a command to the moving average value calculation unit 211 to perform processing to calculate a moving average value of the process value in feedback control.

[0078] In this way, the moving average value may be calculated only when a predetermined condition is satisfied, i.e., when the fluctuation of the process value is transient and it is preferable to use the moving average value in feedback control. By calculating the moving average value of the process value only when the predetermined condition is satisfied, it is possible to suppress an increase in the cost of calculation processing. If the change rate determination unit 215 determines that the change rate of the process value is greater than a predetermined value, the process value may be corrected using a time lag element, or other known signal processing may be performed.

[0079] (Variation 2) Furthermore, the operation determination unit 216 included in the control device 200 determines whether the moving average value is equal to or greater than a predetermined lower limit value during a predetermined period during feedback control. When the change rate determination unit 215 determines that the moving average value is not equal to or greater than the predetermined lower limit value during a predetermined period during feedback control, it may output a command to the alarm unit 217 to issue an alarm.

[0080] In conventional feedback control, when a feedback signal is corrected using a first-order lag element, the effect of the first-order lag element may prevent the corrected feedback signal from reaching a predetermined lower limit value within a predetermined time. In this case, the operation determination unit 216 determines that the corrected feedback signal is below the predetermined lower limit value, i.e., determines that there is an abnormality in the boiler control. The operation determination unit 216 then outputs a command to issue an alarm to the alarm unit 217, temporarily suspending the boiler control. Therefore, even if the current process value is in a state where boiler control can continue, there is a possibility that an alarm will be issued or boiler control will be interrupted unnecessarily due to the influence of the delay element.

[0081] As described above, feedback control using the moving average value of the process value has higher responsiveness than feedback control using a first-order lag element. Therefore, in this modification, the operation determination unit 216 determines whether the moving average value is equal to or greater than a predetermined lower limit value during a predetermined period of time during feedback control. This makes it possible to more accurately determine whether boiler control is being executed normally than when a first-order lag element is used. Therefore, it is possible to reduce the possibility of an alarm being issued or boiler control being interrupted unnecessarily.

[0082] (Variation 3) Furthermore, the first-order lag element calculation unit 220 included in the control device 200 calculates a first-order lag element when it is assumed that a first-order lag element is added to the process value for a predetermined period in order to bring the deviation between the target value and the current process value closer to zero in feedback control. The moving average value calculation unit 211 may set the number of samples used to calculate the moving average value based on the first-order lag element calculated by the first-order lag element calculation unit 220. This ensures the stability of boiler control and improves responsiveness to sudden changes in the process value.

[0083] Although the present disclosure has been described above using embodiments, the technical scope of the present disclosure is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the gist of the present disclosure, and such modifications or improvements are also included in the technical scope of the present disclosure. Furthermore, the above embodiments may be combined as appropriate. For example, the sampling period and the number of samples may be set by the user as appropriate depending on the characteristics of the process value and boiler control. Also, the control device 200 may include a first-order lag element circuit that corrects the process value, which is a feedback signal in feedback control, using a first-order lag element.

[0084] In the above-described embodiment, the boiler of the present disclosure has been described as a boiler that uses solid fuel as fuel, such as coal, biomass fuel, petroleum coke (PC), petroleum residue, etc. The boiler can be fueled not only with solid fuels, but also with petroleum products such as heavy oil, light oil, and crude oil, industrial wastewater, liquefied ammonia, and other liquid fuels. It can also use gaseous fuels such as natural gas, various petroleum gases, by-product gases generated in steelmaking processes, hydrogen gas, and ammonia gas. Furthermore, the present invention can also be applied to a multi-fuel boiler that uses a combination of these various fuels.

[0085] (Additional notes) The boiler control device, the boiler system including the same, the boiler control method, and the boiler control program described in each of the above-described embodiments can be understood, for example, as follows. A boiler control device (200) according to a first aspect of the present disclosure is a boiler control device that performs feedback control, and includes an information acquisition unit (210) that acquires boiler operation information including process values ​​that are input information, a moving average value calculation unit (211) that calculates a moving average value that is a moving average of the process values ​​over a predetermined period, an operation amount calculation unit (213) that calculates an operation amount based on the moving average value calculated by the moving average value calculation unit, and an execution unit (214) that executes boiler control using the operation amount calculated by the operation amount calculation unit.

[0086] According to the boiler control device of the present disclosure, the moving average value calculation unit calculates the moving average value of the process value during feedback control. Then, the manipulated variable calculation unit calculates the manipulated variable using the calculated moving average value of the process value. By calculating the manipulated variable using the moving average value of the process value in this way, it is possible to ensure stability of the feedback control and improve responsiveness to fluctuations in the process value compared to when a first-order lag element is used.

[0087] The boiler control device according to the second aspect of the present disclosure is the first aspect, and includes a change rate determination unit (215) that determines whether the rate of change of the process value over a predetermined period is greater than a predetermined value, and when the change rate determination unit determines that the rate of change of the process value is greater than the predetermined value, the moving average value calculation unit calculates a moving average value of the process value.

[0088] The boiler control device disclosed herein includes a change rate determination unit that determines whether the rate of change of a process value over a predetermined period is greater than a predetermined value, and if the change rate determination unit determines that the rate of change of the process value is greater than the predetermined value, a moving average value calculation unit calculates a moving average value of the process value. This suppresses transient changes in the process value, realizes stable control, and suppresses increases in costs associated with calculation processing.

[0089] A boiler control device according to a third aspect of the present disclosure, in either the first or second aspect, includes an operation determination unit (216) that determines whether or not a moving average value is equal to or greater than a predetermined lower limit value during a predetermined period during feedback control.

[0090] In the boiler control device according to the present disclosure, the operation determination unit determines whether the moving average value is equal to or greater than a predetermined lower limit value during a predetermined period of feedback control. This makes it possible to determine whether the moving average value calculated by the moving average value calculation unit is an appropriate value. In other words, compared to when a first-order lag element is used, it is possible to more accurately determine whether boiler control is being performed normally. Furthermore, for example, if an alarm unit that issues an alarm is further provided and the alarm unit issues an alarm depending on the judgment result of the operation judgment unit, the possibility of an erroneous alarm being issued can be reduced.

[0091] A boiler control device according to a fourth aspect of the present disclosure, in any one of the first to third aspects, includes a first-order lag element calculation unit that calculates a first-order lag element when it is assumed that a first-order lag element is added to the process value over a predetermined period in the feedback control, and the moving average value calculation unit sets the number of samples used when calculating the moving average value based on the first-order lag element.

[0092] The boiler control device according to the present disclosure includes a first-order lag element calculation unit that calculates a first-order lag element assumed to be added to a process value over a predetermined period in feedback control, and a moving average value calculation unit that sets the number of samples used to calculate the moving average value based on the first-order lag element. For example, by setting the number of samples based on the set time of the first-order lag element when calculating the moving average value, it is possible to ensure the stability of boiler control and improve responsiveness to sudden changes in the process value.

[0093] A boiler system according to a fifth aspect of the present disclosure includes a boiler control device according to any one of the first to fifth aspects, a heat exchanger (102, 103, 104) provided in a combustion gas flow path through which combustion gas flows and for recovering heat from the combustion gas, and a boiler (10) that burns pulverized fuel made from pulverized solid fuel using a burner and exchanges the heat generated by the combustion with feedwater or steam to generate superheated steam.

[0094] A boiler control method according to a sixth aspect of the present disclosure is a boiler control method that performs feedback control, and includes an information acquisition step of acquiring boiler operation information including process values ​​that are input information; a moving average value calculation step of calculating a moving average value that is a moving average of the process values ​​over a predetermined period of time; an operation quantity calculation step of calculating an operation quantity based on the moving average value calculated in the moving average value calculation step; and an execution step of executing boiler control using the operation quantity calculated in the operation quantity calculation step.

[0095] A boiler control method according to a seventh aspect of the present disclosure is a boiler control method that performs feedback control, and includes a first-order lag element calculation step that calculates a first-order lag element when it is assumed that the first-order lag element is added to a process value over a predetermined period of time; a moving average value calculation step that calculates a moving average value that is a moving average of the process values ​​over the predetermined period of time; a manipulated variable calculation step that calculates a manipulated variable using either the first-order lag element calculated in the first-order lag element calculation step or the moving average value calculated in the moving average value calculation step; and a change rate determination step that determines whether the rate of change of the process value over the predetermined period of time is greater than a predetermined value, wherein in the manipulated variable calculation step, the manipulated variable is calculated using the calculation result of the moving average value calculation step instead of the calculation result of the first-order lag element calculation step, depending on the determination result of the change rate determination step.

[0096] A boiler control program according to an eighth aspect of the present disclosure is a boiler control program that performs feedback control, and causes a computer to execute an information acquisition process that acquires boiler operation information including process values ​​that are input information; a moving average value calculation process that calculates a moving average value that is a moving average of the process values ​​over a predetermined period; an operation quantity calculation process that calculates an operation quantity based on the moving average value calculated in the moving average value calculation process; and an execution process that executes boiler control using the operation quantity calculated in the operation quantity calculation process. [Explanation of symbols]

[0097] 1. Power Plant 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21 Burner 22 Fine fuel supply pipe 23 Air register 24 Air duct 25 Additional air port 26 Additional air duct 31 Mill (Grinder) 32 Forced draft fan (FDF) 41 Gas duct 42 Air preheater 43 Denitration equipment 44 Dust collection device 45 Induced Draft Fan (IDF) 46 Desulfurization equipment 47 Chimney 101 Furnace wall 102 Superheater 102A 1st superheater 102B 2nd superheater 102C 3rd superheater 103 Reheater 103A 1st reheater 103B 2nd reheater 104 Economizer 111 Steam turbine 111A high pressure turbine 111B Intermediate Pressure Turbine 111C low pressure turbine 112 Condenser 113 Generator 121 Condensate pump (CP) 122 Low pressure water heater 123 Boiler Feed Pump (BFP) 124 High-pressure water heater 125 Brackish water separator 126 Steam separator drain tank 127 Boiler Circulation Pump (BCP) 200 control device 201 CPU 202 Main storage 203 Secondary storage device 204 Communication Interface 205 Input Devices 206 Display 208 Bus 210 Information Acquisition Department 211 Moving average value calculation unit 212 Intermediate calculation section 213 Manipulated amount calculation section 214 Executive Department 215 Change rate determination unit 216 Operation judgment section 217 Alarm section A1 Adder ave1~ave3 Moving average circuit com1~com3 comparator F1,F2 function generator I1,I2 integrator L1 water supply line L2 drain water line L3~L5 steam lines L6 Circulation Line PI1,PI2 PI controller

Claims

1. A boiler control device that performs feedback control, an information acquisition unit that acquires boiler operation information including process values ​​that are input information; a moving average value calculation unit that calculates a moving average value that is a moving average of the process value over a predetermined period; a manipulated variable calculation unit that calculates a manipulated variable based on the moving average value calculated by the moving average value calculation unit; an execution unit that executes control of a boiler using the manipulated variable calculated by the manipulated variable calculation unit; A boiler control device comprising:

2. a change rate determination unit that determines whether a change rate of the process value in a predetermined period is greater than a predetermined value; 2. The boiler control device according to claim 1, wherein the moving average value calculation unit calculates a moving average value of the process value when the change rate determination unit determines that the change rate of the process value is greater than a predetermined value.

3. The boiler control device according to claim 1, further comprising an operation determination unit that determines whether or not the moving average value is equal to or greater than a predetermined lower limit value during a predetermined period during the feedback control.

4. a first-order lag element calculation unit that calculates a first-order lag element when it is assumed that a first-order lag element is added to the process value during a predetermined period in the feedback control; The boiler control device according to claim 1 , wherein the moving average value calculation unit sets the number of samples used when calculating the moving average value based on the first-order lag element.

5. The boiler control device according to any one of claims 1 to 4; a heat exchanger provided in a combustion gas flow path through which the combustion gas flows, for recovering heat from the combustion gas; A boiler that burns pulverized solid fuel with a burner and exchanges the heat generated by this combustion with feedwater or steam to generate superheated steam. A boiler system comprising:

6. A boiler control method that performs feedback control, an information acquisition step of acquiring boiler operation information including process values ​​as input information; a moving average value calculation step of calculating a moving average value that is a moving average of the process value over a predetermined period; a manipulated variable calculation step of calculating a manipulated variable based on the moving average value calculated in the moving average value calculation step; an execution step of executing control of a boiler using the manipulated variable calculated in the manipulated variable calculation step; A method for controlling a boiler having the above construction.

7. A boiler control method that performs feedback control, a first-order lag element calculation step of calculating a first-order lag element when it is assumed that the first-order lag element is added to a process value in a predetermined period; a moving average value calculation step of calculating a moving average value which is a moving average of the process values ​​over a predetermined period; a manipulated variable calculation step of calculating a manipulated variable using either the first-order lag element calculated in the first-order lag element calculation step or the moving average value calculated in the moving average value calculation step; a change rate determination step of determining whether a change rate of the process value in a predetermined period is greater than a predetermined value; and A boiler control method, wherein in the manipulated variable calculation step, the manipulated variable is calculated using the calculation result of the moving average value calculation step instead of the calculation result of the first-order lag element calculation step, depending on the judgment result of the change rate judgment step.

8. A boiler control program that performs feedback control, an information acquisition process for acquiring boiler operation information including process values ​​as input information; a moving average value calculation process for calculating a moving average value that is a moving average of the process value over a predetermined period; a manipulated variable calculation process that calculates a manipulated variable based on the moving average value calculated in the moving average value calculation process; an execution process for executing control of a boiler using the manipulated variable calculated in the manipulated variable calculation process; A boiler control program that causes a computer to execute the above.

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