Boiler control device, boiler control method, and program

Abstract

To stably maintain a state of a boiler when there is a reverse load change requirement during load change of the boiler.SOLUTION: A boiler controller comprises an advance control signal generation unit, a reverse load change condition determination unit, an advance control signal adjustment unit, and a control unit. The advance control signal generation unit generates an advance control signal based on a load change request to a boiler. The reverse load change condition determination unit determines whether or not there is a reverse load change request for load change. The advance control signal adjustment unit adjusts at least one of a target value and a change rate of the advance control signal corresponding to the reverse load change request when the reverse load change condition is satisfied. The control unit controls the boiler based on the advance control signal adjusted by the advance control signal adjustment unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Thermal power plants use boilers to burn fuel and generate steam to drive generators. In conventional base load operation, boilers in thermal power plants are basically operated at rated output, and during times of reduced power demand, such as at night, the operating state is changed to reduce the load, thereby adjusting the output (power generation amount).

[0003] In order to prevent the operating state from becoming unstable due to transient excess or deficiency of boiler input during such boiler load changes, advance control may be performed on control parameters such as the amount of fuel input based on the given load change request (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5970368 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, the boiler load changes in one direction toward the target load, and control is performed based on an advance control signal (BIR: Boiler Input Ratio) corresponding to such a load change. Here, if a load change request is made in the opposite direction to the previous load change before the boiler load reaches the target load, the boiler may become unstable because the conventional advance control signal is adjusted on the assumption that the previous target load will be reached.

[0006] Furthermore, since the advance control signal is generated based on a load change request for the boiler, if a load change request in the opposite direction is made during a load change, both the previous advance control signal and the advance control signal based on the load change request in the opposite direction may be added at the same time. In this case, even after the load change request in the opposite direction is detected, it takes a certain amount of time for the previous advance control signal to disappear (become zero), so an appropriate advance control signal may not be added, and the boiler may become unstable.

[0007] In recent years, thermal power plants equipped with boilers are increasingly being required to function as an adjustment capacity to cover electricity from renewable energy sources, whose power output tends to fluctuate. In conventional thermal power plants designed for baseload operation, the boiler load basically changes in one direction toward a target load, and the advance control signal for the boiler also assumes a load that changes in one direction. However, in recent years, the required load for the boiler can sometimes change in the opposite direction in a short period of time in response to fluctuations in the amount of power generated from renewable energy sources, which can be difficult to handle with the conventional advance control signal.

[0008] At least one embodiment of the present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a boiler control device, a boiler control method, and a program that can stably maintain the state of a boiler when a load change request in the opposite direction occurs during a change in boiler load. [Means for solving the problem]

[0009] In order to solve the above problem, a boiler control device according to at least one embodiment of the present disclosure includes: an advance control signal generator for generating an advance control signal for the boiler based on a load change request for the boiler; a reverse load change condition determination unit for determining whether a reverse load change condition exists for determining whether a load change request in a reverse direction is required for the load change; an advance control signal adjusting unit for adjusting at least one of a target value or a change rate of the advance control signal corresponding to the load change request in the reverse direction when the reverse load change condition is satisfied; a control unit for controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; Equipped with.

[0010] In order to solve the above problem, a boiler control method according to at least one embodiment of the present disclosure includes: generating an advance control signal for the boiler based on a load change request for the boiler; a step of determining whether a reverse load change condition is satisfied to determine whether a reverse load change request exists for the load change; adjusting at least one of a target value or a rate of change of the advance control signal corresponding to the reverse load change request when the reverse load change condition is met; controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; Equipped with.

[0011] In order to solve the above problem, a program according to at least one embodiment of the present disclosure includes: Using a computer, generating an advance control signal for the boiler based on a load change request for the boiler; a step of determining whether a reverse load change condition is satisfied to determine whether a reverse load change request exists for the load change; adjusting at least one of a target value or a rate of change of the advance control signal corresponding to the reverse load change request when the reverse load change condition is met; controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; is possible. [Effects of the Invention]

[0012] According to at least one embodiment of the present disclosure, it is possible to provide a boiler control device, a boiler control method, and a program that can stably maintain the state of a boiler when a load change request in the opposite direction occurs during a change in the boiler load. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a boiler according to an embodiment. [Figure 2] 1 is a block diagram showing a hardware configuration of a boiler control device according to an embodiment. [Figure 3] 1 is a block diagram showing a functional configuration of a boiler control device according to one embodiment. [Figure 4] FIG. 4 is a control flow diagram of the advance control signal generating unit of FIG. 3. [Figure 5] FIG. 10 is a diagram showing a typical transition of an advance control signal when the load change of the boiler is increasing. [Figure 6] 4 is a control flow diagram relating to calculation of a first adjusted change rate of the advance control signal adjuster of FIG. 3. FIG. [Figure 7] FIG. 4 is a control flow diagram of a reverse direction load change condition determination unit in FIG. 3. [Figure 8] FIG. 4 is a control flow diagram of the advance control signal adjuster of FIG. 3. [Figure 9] 10A and 10B are diagrams illustrating load changes and advance control signal changes over time in a boiler control device according to a comparative example. [Figure 10] 4 is a diagram showing a load change and a time change of an advance control signal in the boiler control device of FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0015] First, a boiler that is a control target of a boiler control device according to some embodiments of the present disclosure will be described. Fig. 1 is a schematic configuration diagram of a boiler 10 according to one embodiment.

[0016] The boiler 10 is a boiler that uses a burner to burn pulverized solid fuel, which is the main fuel, and exchanges the heat generated by this combustion with feedwater or steam to generate superheated steam. Biomass fuel, coal, etc. are used as the 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 multiple 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 collectively referred to as "burners 21" where appropriate) 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) as one set, and are arranged in multiple stages along the vertical direction.

[0019] 1, for convenience of illustration, only two of one set of burners are shown, 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 stages, the number of burners per stage, the arrangement of the burners, etc. are not limited to this embodiment.

[0020] Burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, collectively referred to as "mills 31") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (hereinafter, collectively referred to as "pulverized fuel supply pipes 22"), respectively. 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.

[0021] 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 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.

[0022] 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 collectively referred to as "superheaters 102" as appropriate), reheaters 103A and 103B (hereinafter collectively referred to as "reheaters 103" as appropriate), 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 the feedwater or steam flowing inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to the form shown in FIG.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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. In addition, 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), but the oxidizing gas may have a higher or lower oxygen content than air, and stable combustion can be achieved in the furnace 11 by adjusting the ratio of the amount of oxygen to the amount of fuel supplied within an appropriate range.

[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 a coal economizer 104, which are arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in the denitration device 43, the combustion gas exchanges heat with primary air and secondary air in the air preheater 42, and is then discharged into the gas duct 41, where ash and the like are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46, and the combustion gas is then discharged to the outside of the system through a chimney 47. The arrangement of the heat exchangers in the combustion gas passage 12 and the devices from the flue 13 to the gas duct 41 does not necessarily have to be in the order described above with respect to the flow of combustion gas.

[0028] Next, a description will be given of a boiler control device 100 that controls the boiler 10 having the above configuration. Fig. 2 is a block diagram showing the hardware configuration of the boiler control device 100 according to one embodiment.

[0029] The boiler control device 100 is configured as an arithmetic processing device such as a computer. The hardware configuration of the boiler control device 100 includes an input unit 110, a storage unit 120, a calculation unit 130, and an output unit 140, as shown in FIG.

[0030] The input unit 110 is configured to input various information necessary for the calculation processing performed in the boiler control device 100. The input unit 110 may be a human interface such as a mouse, keyboard, or touch panel that can be operated by an operator, or an interface device for acquiring various information from other devices including the boiler 10 that is the object of control.

[0031] The storage unit 120 is configured to store various types of information necessary for the arithmetic processing performed in the boiler control device 100. The storage unit 120 is configured from a computer-readable storage medium including at least one of RAM (Random Access Memory) and ROM (Read Only Memory). The various types of information stored in the storage unit 120 include programs that enable these hardware configurations to function as the boiler control device 100.

[0032] The calculation unit 130 is configured to perform various calculations of the boiler control device 100, and includes, for example, a CPU (Central Processing Unit). The calculation unit 130 reads out the programs stored in the storage unit 120 into a RAM or the like and executes information processing and calculation processing, thereby realizing various functions of the boiler control device 100.

[0033] The program executed by the calculation unit 130 may be stored in the storage unit 120 as described above, or may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means, etc. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0034] The output unit 140 is configured to perform output based on the calculation result in the calculation unit 130. In this embodiment, the output unit 140 outputs a control signal to the boiler 10, which is the object of control, as the output of the boiler control device 100. By receiving the control signal, the boiler 10 is controlled based on the control signal.

[0035] In addition to outputting a control signal to the boiler 10 that is the object of control, the output unit 140 may also include a human interface such as a display for an operator to recognize the calculation results, or a notification means for issuing an alarm in accordance with the calculation results.

[0036] Next, a functional configuration of the boiler control device 100 will be described. Fig. 3 is a block diagram showing the functional configuration of the boiler control device 100 according to one embodiment. The boiler control device 100 includes a control unit 150, an advance control signal generation unit 160, a reverse load change condition determination unit 170, and an advance control signal adjustment unit 180.

[0037] The block diagram shown in FIG. 3 is an example showing the functional configuration of the boiler control device 100 in accordance with the following description, and each block may be integrated with another or further subdivided.

[0038] The control unit 150 is configured to control the boiler 10 by generating a control signal corresponding to a control parameter of a control target based on an input parameter relating to the operating state of the boiler 10.

[0039] The advance control signal generating unit 160 is configured to generate an advance control signal (BIR: Boiler Input Ratio) for the control signal handled by the control unit 150. The advance control signal BIR is generated based on a load change request for the boiler that is known in advance, and is intended to prevent the boiler operating state from becoming unstable due to a transient excess or deficiency of boiler input (such as fuel supply amount) toward the target load. In this embodiment, as an example, the advance control signal BIR is generated based on a load index indicating the boiler load, a load change rate (speed of load change), and a load change width (difference between the current boiler load value and the target load).

[0040] The control signals (control parameters) to be corrected by the preceding control signal are, for example, parameters that have a large effect on steam temperature control, and specifically, the fuel flow rate, combustion air flow rate, gas damper opening, and superheater spray flow rate can be used.

[0041] The reverse load change condition determination unit 170 is configured to determine whether a reverse load change condition is met to determine whether a request for a reverse load change is made during a boiler load change. A reverse load change refers to a case where a load change in the reverse direction occurs by changing the target load during a load change in one direction (increasing or decreasing) toward the target load. The reverse load change condition determination unit 170 outputs a signal corresponding to the determination result regarding whether or not such a request for a reverse load change is made.

[0042] The advance control signal adjuster 180 is configured to adjust the advance control signal BIR generated by the advance control signal generator 160 when the reverse load change condition determiner 170 determines that the reverse load change condition is met. The advance control signal BIR is adjusted for at least one of the target value BIRt of the advance control signal BIR or the rate of change of the advance control signal BIR. As a result, when the reverse load change condition determiner 170 determines that the reverse load change condition is not met, the control unit 150 performs control using the advance control signal BIR based on the default value (a value not adjusted by the advance control signal adjuster 180) generated by the advance control signal generator 160. On the other hand, when the reverse load change condition determiner 170 determines that the reverse load change condition is met, the control unit 150 performs control using the advance control signal BIR adjusted by the advance control signal adjuster 180.

[0043] Next, the function of each component shown in Fig. 3 will be described in detail with reference to a control flow diagram. Fig. 4 is a control flow diagram of the advance control signal generator 160 in Fig. 3.

[0044] The advance control signal generator 160 receives as input parameters the load index, which is the control target value of the boiler load, the load change rate, which is the rate of change of the boiler load, and the load change width, which is the difference between the load at the start of the boiler load change and the load at the completion of the load change, to generate an advance control signal BIR. The behavior of the advance control signal BIR is determined by the target value BIRt and the change rate (speed of change). For example, in the case of a thermal power plant, the load index is a power generation command (MWD) for the plant. The load of the boiler is controlled using the power generation command as a control target value.

[0045] The behavior of a typical advance control signal BIR will now be described with reference to Fig. 5. Fig. 5 is a diagram showing the transition of a typical advance control signal BIR with a load change when the load on the boiler increases.

[0046] FIG. 5 shows a case in which the boiler load, which has an initial value L1, begins to increase at time t1 and reaches a target value L2 at time t2. At this time, the advance control signal BIR begins to increase from time t1 according to a first rate of change R1 (constant value) preset as the rate of change during the increase, and changes to reach the target value BIRt at time t3. Typically, time t3 is before time t2, and the advance control signal BIR, which reaches the target value BIRt at time t3, remains constant until time t2, when the boiler load change ends. Then, when the boiler load change ends at time t2, the advance control signal BIR gradually decreases from the target value BIRt to zero according to a second rate of change R2 (constant value) preset as the rate of change during the decrease. As a result, the advance control signal BIR becomes zero at time t4. In this way, after time t2 when the boiler load reaches the target value L2 and the boiler operation is stabilized, the advance control signal BIR, which is input to stabilize the operating state during a change in the boiler load, is removed, thereby preventing the advance control signal BIR from becoming a disturbance.

[0047] Returning to Figure 4, in the advance control signal generating unit 160, the input parameters of the load index, load change rate, and load change width are input to functions fx1, fx2, and fx3, respectively, and the respective outputs are multiplied to obtain the target value BIRt of the advance control signal BIR.

[0048] In the advance control signal generator 160, the load indexes, which are input parameters, are input to functions fx4 and fx5, and a first change rate R1 and a second change rate R2 are calculated based on the respective calculation results. Based on the target value BIRt of the advance control signal BIR, the first change rate R1, and the second change rate R2 calculated in this way, the advance control signal generator 160 generates the advance control signal BIR so as to realize the behavior of the advance control signal BIR exemplarily described with reference to FIG.

[0049] In this embodiment, in addition to a configuration for realizing such a typical behavior of the advance control signal BIR, the advance control signal generation unit 160 is configured to be able to adjust at least one of the target value or the change rate of the advance control signal BIR using a reverse load change condition determination unit 170 and an advance control signal adjustment unit 180. Specifically, the advance control signal generation unit 160 is configured to adjust the target value BIRt of the advance control signal BIR by multiplying the calculation result (default value of the target value BIRt) of functions fx1, fx2, and fx3 corresponding to the target value of the advance control signal BIR by a correction coefficient AN, a first switching unit 174 for switching the first change rate R1 described above to a first adjusted change rate R1′ adjusted by the advance control signal adjustment unit 180 based on the determination result of the reverse load change condition determination unit 170, and a second switching unit 176 for switching the second change rate R2 described above to a second adjusted change rate R2′ adjusted by the advance control signal adjustment unit 180.

[0050] The target value adjustment unit 171 is configured to adjust the target value BIRt of the advance control signal BIR by multiplying the calculation results (default values of the target value BIRt) of functions fx1, fx2, and fx3 corresponding to the target value of the advance control signal BIR by a correction coefficient AN calculated by the advance control signal adjustment unit 180. This makes it possible to adjust the target value BIRt of the advance control signal BIR, which is a default value, based on the correction coefficient AN according to the operating state of the boiler.

[0051] The first switching unit 174 is configured to select the above-mentioned first change rate R1, which is a default value, when the reverse load change condition determination unit 170 determines that there is no reverse load change, and to select the first adjusted change rate R1' adjusted by the advance control signal adjuster 180 when the reverse load change condition determination unit 170 determines that there is a reverse load change. In this way, when a reverse load change occurs, the change rate corresponding to an increase in the advance control signal BIR can be switched from the first change rate R1, which is the default value, to the first adjusted change rate R1' adjusted by the advance control signal adjuster 180.

[0052] The second switching unit 176 is configured to select the above-mentioned second change rate R2, which is a default value, when the reverse load change condition determination unit 170 determines that there is no reverse load change, and to select the second adjusted change rate R2' adjusted by the advance control signal adjuster 180 when the reverse load change condition determination unit 170 determines that there is a reverse load change. In this way, when a reverse load change occurs, the change rate corresponding to an increase in the advance control signal BIR can be switched from the second change rate R2, which is the default value, to the second adjusted change rate R2' adjusted by the advance control signal adjuster 180.

[0053] FIG. 6 is a control flow diagram for calculating the first adjusted rate of change R1′ in the advance control signal adjuster 180 of FIG. 3. The first adjusted rate of change R1′ is calculated based on a load index corresponding to the boiler load and a heat absorption index (HAI) signal for each boiler section corresponding to the boiler operating conditions. In this embodiment, the coal type (type of fuel) used in the boiler is used as a parameter affecting the heat absorption state of each boiler section, and the HAI signal is given in advance as a numerical value corresponding to the coal type used. For example, coal types can be classified by fuel ratio (the ratio of the fixed carbon content in coal divided by the volatile content), and the HAI signal is set as an input parameter for functions fx7, fx9, and fx11 that output allocation ratios for a high fuel ratio coal setting (function fx6), a medium fuel ratio coal setting (fx8), and a low fuel ratio coal setting (fx10) that are prepared in advance and adjusted during test operation or the like, depending on the fuel ratio of the coal type used.

[0054] The control flow shown in FIG. 6 includes a first adjusted change rate calculation unit 182A for calculating a first adjusted change rate R1′A corresponding to a high fuel ratio coal setting, a second adjusted change rate calculation unit 182B for calculating a second adjusted change rate R1′B corresponding to a medium fuel ratio coal setting, and a third adjusted change rate calculation unit 182C for calculating a third adjusted change rate R1′C corresponding to a low fuel ratio coal setting. The first adjusted change rate calculation unit 182A calculates the first adjusted change rate R1′A by multiplying the result of a calculation in which a load index is input to a function fx6 by the result of a calculation in which an HAI signal is input to a function fx7. The second adjusted change rate calculation unit 182B calculates the second adjusted change rate R1′B by multiplying the result of a calculation in which a load index is input to a function fx8 by the result of a calculation in which an HAI signal is input to a function fx9. The third adjusted change rate calculation unit 182C calculates the third adjusted change rate R1'C by multiplying the calculation result of inputting the load index to function fx10 by the calculation result of inputting the HAI signal to function fx11. The first adjusted change rate R1'A, second adjusted change rate R1'B, and third adjusted change rate R1'C calculated in this way are added (proportionally divided) at a ratio based on the HAI signal, and the result of this calculation is multiplied by the result of inputting the HAI signal to function fx12 to calculate the adjusted change rate R1'.

[0055] Although not shown in the drawings in this embodiment, the control flow diagram for calculating the second adjusted change rate R2' is also configured in accordance with FIG.

[0056] Next, Fig. 7 is a control flow diagram of the reverse load change condition determination unit 170 of Fig. 3. The reverse load change condition determination unit 170 acquires a load index corresponding to the boiler load, a load change rate, and a load change width as input parameters, and determines whether the reverse load change condition is met based on these input parameters. For example, the reverse load change condition determination unit 170 determines that the reverse load change condition is met when both the following first and second conditions are met. First condition: The load change range is greater than or equal to the threshold. Second condition: A load change request in the opposite direction to the load change direction is detected during the load change. If at least one of the first condition and the second condition is not satisfied, the reverse load change condition determining unit 170 determines that the reverse load change condition is not established.

[0057] Specifically, as shown in Fig. 7, the reverse-direction load change condition determination unit 170 determines whether the first condition is met by the first determination unit 172 determining whether a load change (load increase) in one direction has continued for a predetermined period or more and whether the load change magnitude is equal to or greater than a threshold. The determination result of the first determination unit 172 is maintained for a predetermined period. The second determination unit 173 determines whether the first determination unit 172 has determined that the conditions are met and whether a load change has occurred in the opposite direction. When the first determination unit 172 and the second determination unit 173 determine that the first condition and the second condition are met, the reverse-direction load change condition determination unit 170 outputs a determination signal indicating that the reverse-direction load change condition is met.

[0058] 8 is a control flow diagram of the advance control signal adjuster 180 of FIG. 3. The advance control signal adjuster 180 calculates a correction coefficient AN for adjusting the target value BIRt of the advance control signal BIR based on a load index corresponding to the boiler load and an HAI signal corresponding to the boiler operating conditions. In this embodiment, the coal type (type of fuel) used in the boiler is used as the boiler operating condition, and the HAI signal is given in advance as a numerical value corresponding to the coal type, as described above. For example, coal types can be classified by fuel ratio, and the HAI signal is set as an input parameter for functions fx13, fx15, and fx17 that output allocation ratios corresponding to a pre-prepared high fuel ratio coal setting (function fx12), a medium fuel ratio coal setting (fx14), and a low fuel ratio coal setting (fx16) according to the fuel ratio of the coal type used.

[0059] The advance control signal adjuster 180 includes a first correction coefficient calculator 184A for calculating a first correction coefficient AN1 corresponding to a high fuel ratio coal setting, a second correction coefficient calculator 184B for calculating a second correction coefficient AN2 corresponding to a medium fuel ratio coal setting, and a third correction coefficient calculator 184C for calculating a third correction coefficient AN3 corresponding to a low fuel ratio coal setting. The first correction coefficient calculator 184A calculates the first correction coefficient AN1 by multiplying the result of a calculation in which a load index is input to a function fx12 by the result of a calculation in which an HAI signal is input to a function fx13. The second correction coefficient calculator 184B calculates the second correction coefficient AN2 by multiplying the result of a calculation in which a load index is input to a function fx14 by the result of a calculation in which an HAI signal is input to a function fx15. The third correction coefficient calculation unit 184C calculates the third correction coefficient AN3 by multiplying the calculation result of function fx16, in which the load index is input, by the calculation result of function fx17, in which the HAI signal is input. The first correction coefficient AN1, second correction coefficient AN2, and third correction coefficient AN3 calculated in this way are added (proportionally divided) at a ratio based on the HAI signal, thereby calculating the correction coefficient AN.

[0060] 7, the correction coefficient AN calculated by the advance control signal adjuster 180 can be switched to a default value (=1.0) of the correction coefficient AN by the third switcher 178 of the reverse load change condition determiner 170. Based on the determination result of the reverse load change condition determiner 170, the third switcher 178 switches the correction coefficient AN between the calculation result (≠1.0) of the advance control signal adjuster 180 and the default value (=1.0), thereby making it possible to adjust the target value BIRt of the advance control signal BIR.

[0061] Next, the operation of the boiler control device 100 having the above configuration will be described using an example in which the boiler load changes in the opposite direction (downward) while it is increasing. Figure 9 is a diagram showing the load change and the advance control signal BIR change over time in a boiler control device according to a comparative example, and Figure 10 is a diagram showing the load change and the advance control signal BIR change over time in the boiler control device 100 of Figure 3.

[0062] The comparative example shown in FIG. 9 has a common configuration with the boiler control device 100 of this embodiment having the above-described configuration, except that it does not have the reverse load change condition determination unit 170 and the advance control signal adjustment unit 180 (i.e., in the comparative example, the advance control signal BIR is not adjusted when the reverse load change condition is met).

[0063] In Figures 9 and 10, the boiler load increases at a predetermined rate from an initial value L1 toward the target load L2 at time t1, but at time ta before the load reaches the target load L2, the load changes in the opposite direction, decreasing from load L3 (<target load L2) at a predetermined rate and returning to the initial value L1 at time tb.

[0064] First, in the comparative example shown in FIG. 9 , the advance control signal generator 160 begins increasing the advance control signal BIR at a first change rate R1 at time t1, when the load begins to increase. The advance control signal BIR reaches a target value BIRt at time t3 and remains constant. Then, when the load change reverses direction at time ta, the advance control signal generator 160 decreases the advance control signal BIR corresponding to the previous load change toward the target load L2 to zero at a second change rate R2, and decreases the advance control signal BIR′ corresponding to the new (later) load change that began at time ta toward the target value BIRt′ at the second change rate R2. Once the advance control signal BIR′ reaches the target value BIRt′, it is maintained at the target value BIRt′ during the subsequent load change. When the load change ends at time tb, it increases to zero at the first change rate R1. Thus, in the comparative example, the advance control signal BIR corresponding to the previous load change remains for a certain period of time from time ta. In this state, if an advance control signal BIR' corresponding to a subsequent load change is input, the remaining advance control signal BIR may act as a disturbance, causing the operating state of the boiler to become unstable.

[0065] In contrast to this, in the present embodiment shown in Fig. 10, when the load change shifts to the reverse direction at time ta, the reverse load change condition determination unit 170 determines that the reverse load change condition is met, and the advance control signal adjustment unit 180 adjusts the advance control signal BIR. This adjustment is performed on at least one of the target value or change rate of the advance control signal BIR' corresponding to the subsequent load change starting from time ta. As a result, as shown in Fig. 10, the advance control signal BIR' corresponding to the subsequent load change from time ta is appropriately adjusted, thereby stabilizing the operating state of the boiler.

[0066] 10 in particular shows a first adjustment pattern P1 and a second adjustment pattern P2 as adjustment patterns for the advance control signal BIR' corresponding to a load change after time ta. In the first adjustment pattern P1, the target value BIRt' of the advance control signal BIR', the first adjusted change rate R1', and the second adjusted change rate R2' are each adjusted to be smaller than the default values, thereby accelerating the decrease in the advance control signal BIR' from time ta to time tc compared to FIG. 9. This minimizes the influence of BIR before the reverse load change, enabling stable boiler control.

[0067] On the other hand, in the second adjustment pattern P2, the target value BIRt'' of the advance control signal BIR' corresponding to the new load change from time ta, the first adjusted change rate R1', and the second adjusted change rate R2' are all adjusted to be larger than the default values, thereby suppressing the decrease in the advance control signal BIR from time ta to time tc compared to Fig. 9. This makes it possible to adjust the BIR amount according to the unstable boiler state during the load change, thereby enabling stable boiler control.

[0068] As described above, according to the above embodiment, when it is determined that the reverse load change condition is satisfied during the load change, at least one of the target value and the change rate of the advance control signal BIR generated based on the load change is adjusted. As a result, even when the load change direction reverses, the advance control signal BIR corresponding to the initial load change is prevented from acting as a disturbance on the boiler operation, and the operating state of the boiler can be effectively stabilized.

[0069] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0070] The control parameters to be corrected by the advance control signal BIR' can be parameters that have a large effect on steam temperature control, such as the fuel flow rate, combustion air flow rate, gas damper opening, and superheater spray flow rate.

[0071] The contents described in each of the above embodiments can be understood, for example, as follows.

[0072] (1) A boiler control device according to one aspect includes: an advance control signal generator (160) for generating an advance control signal (BIR) for the boiler (10) based on a load change request for the boiler; a reverse load change condition determination unit (170) for determining whether a reverse load change condition is satisfied, for determining whether a reverse load change request exists for the load change; an advance control signal adjusting unit (180) for adjusting at least one of a target value or a change rate of the advance control signal corresponding to the load change request in the reverse direction when the reverse load change condition is established; a control unit (150) for controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; Equipped with.

[0073] According to the above aspect (1), when it is determined that a reverse load change condition is met during the load change, the advance control signal generated based on a load change request for the boiler has its target value or change rate adjusted. This prevents the advance control signal corresponding to the initial load change from acting as a disturbance on the boiler operation even when the load change direction reverses, and effectively stabilizes the operating state of the boiler.

[0074] (2) In another embodiment, in the above embodiment (1), When the reverse load change condition is met, the advance control signal adjustment unit adjusts the target value of the advance control signal using a correction coefficient (AN) calculated based on the operating conditions of the boiler and the load index of the boiler.

[0075] According to the above aspect (2), by calculating a correction coefficient for adjusting the advance control signal based on the boiler operating conditions and the load index, when the direction of change in the load reverses, the target value of the advance control signal can be appropriately adjusted to stabilize the boiler operating state.

[0076] (3) In another embodiment, in the above embodiment (2), The operating condition is a fuel ratio of fuel used in the boiler, The correction coefficient is calculated by proportionally dividing the calculation results calculated for each fuel ratio based on the operating conditions.

[0077] According to the above aspect (3), by apportioning the calculation results calculated for each fuel ratio of the fuel used in the boiler based on the operating conditions, it is possible to suitably calculate a correction coefficient that can adjust the advance control signal so as to stabilize the operating state of the boiler when the load change direction reverses.

[0078] (4) In another embodiment, in any one of the above (1) to (3), When the reverse load change condition is met, the advance control signal adjustment unit adjusts the rate of change of the advance control signal corresponding to the load change to an adjusted rate of change calculated based on the operating conditions of the boiler and the load index of the boiler.

[0079] According to the above aspect (4), by adjusting the rate of change of the advance control signal based on the boiler operating conditions and the load index, the operating state of the boiler can be suitably stabilized when the direction of change in the load reverses.

[0080] (5) In another embodiment, in the above embodiment (4), The operating condition is a fuel ratio of fuel used in the boiler, The adjusted change rate is calculated by proportionally dividing the calculation results calculated for each fuel ratio based on the operating conditions.

[0081] According to the above aspect (5), by apportioning the calculation results calculated for each fuel ratio of the fuel used in the boiler based on the operating conditions, when the direction of change in the load changes in the opposite direction, the rate of change of the advance control signal can be suitably adjusted so as to stabilize the operating state of the boiler.

[0082] (6) In another embodiment, in any one of the above (1) to (5), The reverse direction load change condition determination unit determines that the reverse direction load change condition is met when both a first condition, that is, the load change magnitude in the load change is equal to or greater than a threshold value, and a second condition, that a load change request in the opposite direction to the change direction in the load change is detected, are met.

[0083] According to the above aspect (6), it is possible to suitably determine whether the reverse load change condition is met based on both the first condition and the second condition.

[0084] (7) In another embodiment, in the above embodiment (6), The reverse direction load change condition determining unit determines that the first condition is met when the load change continues for a predetermined period or more and a load change width in the load change is equal to or greater than a threshold value.

[0085] According to the above aspect (7), the first condition determines that the load change range remains above a threshold for a predetermined period of time or more. This makes it possible to target load changes of a certain magnitude without detecting minute load fluctuations based on output correction (AFC signal) due to a deviation in the frequency signal, thereby achieving stable boiler control.

[0086] (8) A boiler control method according to one aspect includes: generating an advance control signal for the boiler based on a load change request for the boiler; a step of determining whether a reverse load change condition is satisfied to determine whether a reverse load change request exists for the load change; adjusting at least one of a target value or a rate of change of the advance control signal corresponding to the reverse load change request when the reverse load change condition is met; controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; Equipped with.

[0087] According to the above aspect (8), when it is determined that a reverse load change condition is met during the load change, at least one of the target value and the change rate of the advance control signal generated based on a load change request for the boiler is adjusted. This prevents the advance control signal corresponding to the initial load change from acting as a disturbance on the boiler operation even when the load change direction reverses, and effectively stabilizes the operating state of the boiler.

[0088] (9) A program according to one aspect includes: Using a computer, generating an advance control signal for the boiler based on a load change request for the boiler; a step of determining whether a reverse load change condition is satisfied to determine whether a reverse load change request exists for the load change; adjusting at least one of a target value or a rate of change of the advance control signal corresponding to the reverse load change request when the reverse load change condition is met; controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; is possible.

[0089] According to the above aspect (9), when it is determined that a reverse load change condition is met during the load change, the advance control signal generated based on a load change request for the boiler has its target value or change rate adjusted. This prevents the advance control signal corresponding to the initial load change from acting as a disturbance on the boiler operation even when the load change direction reverses, and effectively stabilizes the operating state of the boiler. [Explanation of symbols]

[0090] 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21 Burner 22 Fine fuel supply pipe 23 Wind Box 24 Wind road 31 mil 32 Forced draft fan 41 Gas duct 42 Air preheater 43 Denitration equipment 44 Dust collection device 46 Desulfurization equipment 47 Chimney 100 Boiler control device 101 Furnace wall 102 Superheater 103 Reheater 104 Economizer 110 Input section 120 Storage section 130 Arithmetic section 140 Output section 150 control section 160 Advance control signal generator 170 Reverse load change condition determination unit 171 Target value adjustment unit 172 1st Judgment Department 173 Second Judgment Department 174 First Switching Unit 176 Second Switching Section 178 Third Switching Section 180 Advance control signal adjustment unit 182A First adjusted change rate calculation unit 182B second adjusted change rate calculation unit 182C Third adjusted change rate calculation unit 184A First correction coefficient calculation unit 184B Second correction coefficient calculation unit 184C Third correction coefficient calculation unit AN correction factor AN1 First correction factor AN2 Second correction factor AN3 Third correction factor BIR Advance Control Signal

Claims

1. an advance control signal generator for generating an advance control signal for the boiler based on a load change request for the boiler; a reverse load change condition determination unit for determining whether a reverse load change condition exists for determining whether a load change request in a reverse direction is required for the load change; an advance control signal adjusting unit for adjusting at least one of a target value or a change rate of the advance control signal corresponding to the load change request in the reverse direction when the reverse load change condition is satisfied; a control unit for controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; A boiler control device comprising:

2. 2. The boiler control device according to claim 1, wherein when the reverse load change condition is met, the advance control signal adjustment unit adjusts the target value of the advance control signal using a correction coefficient calculated based on the operating conditions of the boiler and the load index of the boiler.

3. The operating condition is a fuel ratio of fuel used in the boiler, The boiler control device according to claim 2 , wherein the correction coefficient is calculated by proportionally dividing the calculation results calculated for each of the fuel ratios based on the operating conditions.

4. 4. The boiler control device according to claim 1, wherein when the reverse load change condition is met, the advance control signal adjuster adjusts the rate of change of the advance control signal corresponding to the load change to an adjusted rate of change calculated based on the operating conditions of the boiler and a load index of the boiler.

5. The operating condition is a fuel ratio of fuel used in the boiler, The boiler control device according to claim 4 , wherein the adjusted change rate is calculated by proportionally dividing the calculation results calculated for each of the fuel ratios based on the operating conditions.

6. 6. The boiler control device according to claim 1, wherein the reverse load change condition determination unit determines that the reverse load change condition is met when both a first condition, in which a load change width in the load change is equal to or greater than a threshold value, and a second condition, in which a load change request in a direction opposite to the change direction in the load change is detected, are met.

7. 7. The boiler control device according to claim 6, wherein the reverse direction load change condition determination unit determines that the first condition is met when the load change continues for a predetermined period of time or more and a load change width in the load change is equal to or greater than a threshold value.

8. generating an advance control signal for the boiler based on a load change request for the boiler; a step of determining whether a reverse load change condition is satisfied to determine whether a reverse load change request exists for the load change; adjusting at least one of a target value or a rate of change of the advance control signal corresponding to the reverse load change request when the reverse load change condition is met; controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; A boiler control method comprising:

9. Using a computer, generating an advance control signal for the boiler based on a load change request for the boiler; a step of determining whether a reverse load change condition is satisfied to determine whether a reverse load change request exists for the load change; adjusting at least one of a target value or a rate of change of the advance control signal corresponding to the reverse load change request when the reverse load change condition is met; controlling the boiler based on the advance control signal adjusted by the advance control signal adjustment unit; executable program.

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