Control device and control method

Abstract

This control device controls the supply of fuel including coal and fuel ammonia to a plurality of burner groups each including a plurality of burners. The control device comprises: a mill master control unit that calculates a coal flow rate command indicating a target value for the total coal flow rate by using a total fuel flow rate command indicating a target value for the total flow rate of fuel and a total fuel ammonia flow rate indicating a measured value of the total flow rate of fuel ammonia, and calculates a mill master command indicating a fuel operation amount for each of a plurality of burner groups through feedback computation based on the deviation between the coal flow rate command and a measured value of the total coal supply amount; and a coal feeder control unit that calculates, for each of the plurality of burner groups, a coal supply amount command indicating a target value for the coal supply amount on the basis of the mill master command and the calculated value or the measured value of the flow rate of the fuel ammonia, and outputs the coal supply amount command.

Description

Control device and control method

[0001] The present disclosure relates to a control device and a control method.

[0002] Conventionally, boilers that use coal as fuel are known. The coal is dried and crushed and supplied to a burner. The burner burns the fuel to heat the boiler. The boiler generates steam and supplies it to a steam turbine. The steam is used for power generation, etc.

[0003] In recent years, research has been conducted into the use of ammonia as a fuel. Patent Document 1 describes a boiler operation system that performs mono-combustion of ammonia fuel and co-combustion of ammonia fuel with other fuels. The invention described in Patent Document 1 starts supplying ammonia fuel after the boiler is placed under specific conditions.

[0004] Japanese Patent Application Laid-Open No. 2022-155820

[0005] Conventional thermal power plants and the like have performed mono-fuel combustion, burning only coal, and there have been no large-scale facilities for mixed combustion, burning coal and fuel ammonia. The invention described in Patent Document 1 is a technology that uses ammonia as the main fuel, and cannot utilize existing facilities. Therefore, there is a need for stable mono-fuel combustion and mixed combustion.

[0006] The present disclosure provides a technology that enables stable mono-fuel combustion and multi-fuel combustion.

[0007] A control device according to one aspect of the present disclosure controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups each including a plurality of burners. The control device includes: a mill master control unit that calculates a coal flow rate command that indicates a target value of the total coal flow rate using a total fuel flow rate command that indicates a target value of the total fuel flow rate and a total fuel ammonia flow rate that indicates a measured value of the total fuel ammonia flow rate, and calculates a mill master command that indicates a fuel manipulation amount for each of the plurality of burner groups by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate; and a coal feeder control unit that calculates a coal feed rate command that indicates a target value of the coal feed rate for each of the plurality of burner groups based on the mill master command and the calculated or measured value of the fuel ammonia flow rate (the fuel ammonia flow rate for each stage), and outputs the coal feed rate command.

[0008] According to the present disclosure, it is possible to provide a technology that enables stable mono-fuel combustion and multi-fuel combustion.

[0009] Fig. 1 is a block diagram illustrating a configuration of a control device according to an embodiment. Fig. 2 is a flowchart illustrating an example of the operation of the control device. Fig. 3 is a diagram illustrating an example of the flow of a calculation process for a coal feed rate command. Fig. 4 is a diagram illustrating an example of the flow of a calculation process for fuel ammonia. Fig. 5 is a diagram illustrating an example of the operation of a control submodule. Fig. 6 is a diagram illustrating another example of the operation of the control submodule. Fig. 7 is a diagram illustrating yet another example of the operation of the control submodule. Fig. 8 is a diagram illustrating an example of a hardware configuration related to the control device.

[0010] A control device according to one aspect of the present disclosure controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups each including a plurality of burners. The control device includes: a mill master control unit that calculates a coal flow rate command that indicates a target value of the total coal flow rate using a total fuel flow rate command that indicates a target value of the total fuel flow rate and a total fuel ammonia flow rate that indicates a measured value of the total fuel ammonia flow rate, and calculates a mill master command that indicates a fuel manipulation amount for each of the plurality of burner groups by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate; and a coal feeder control unit that calculates a coal feed rate command that indicates a target value of the coal feed rate for each of the plurality of burner groups based on the mill master command and the calculated or measured value of the fuel ammonia flow rate (the fuel ammonia flow rate for each stage), and outputs the coal feed rate command.

[0011] A control method according to one aspect of the present disclosure controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups, each of which includes a plurality of burners. The control method includes the steps of: calculating a coal flow rate command indicating a target value of the total coal flow rate, using a total fuel flow rate command indicating a target value of the total fuel flow rate and a total fuel ammonia flow rate indicating a measured value of the total fuel ammonia flow rate; calculating a mill master command indicating a fuel manipulation amount for each of the plurality of burner groups by feedback calculation based on a deviation between the coal flow rate command and the measured value of the total coal feed rate; and calculating a coal feed rate command indicating a target value of the coal feed rate for each of the plurality of burner groups, based on the mill master command and the calculated or measured value of the fuel ammonia flow rate (the fuel ammonia flow rate for each stage), and outputting the coal feed rate command.

[0012] In a control device and a control method according to an aspect of the present disclosure, a coal flow rate command is calculated from a total fuel flow rate command and a total fuel ammonia flow rate, a mill master command is calculated by feedback calculation based on the deviation between the coal flow rate command and a measured value of the total coal feed rate, and a coal feed rate command is calculated for each of a plurality of burner groups from the mill master command and the calculated or measured value of the fuel ammonia flow rate, and the coal feed rate command is output. In a control device and a control method according to an aspect of the present disclosure, the coal feed rate is controlled by outputting a coal feed rate command that causes each stage to follow the coal feed rate in accordance with an increase or decrease in the fuel ammonia flow rate in each stage. That is, the coal feed rate command for each stage decreases the coal feed rate in accordance with an increase in the fuel ammonia flow rate in each stage. Furthermore, the coal feed rate command for each stage increases the coal feed rate in accordance with a decrease in the fuel ammonia flow rate in each stage. For example, even when differences in the fuel ammonia flow rate in each stage occur due to the ignition or extinguishing of a fuel ammonia burner associated with switching between mono-fuel combustion and dual-fuel combustion, automatic control is possible while maintaining uniform heat loads in each stage and maintaining stable combustion. As a result, both mono-fuel and mixed-fuel combustion can be performed stably. In addition, existing equipment (such as control devices for mono-fuel combustion of coal) can be utilized, and the scope of modifications can be limited to the part related to the control of fuel ammonia.

[0013] In each of the multiple burners, the coal flow path and the fuel ammonia flow path may be coaxial. The coal flow path and the fuel ammonia flow path are coaxial, and coaxial combustion is performed in which the coal and fuel ammonia are burned coaxially. If coaxial combustion were performed without applying the technology of the present disclosure, for example, the supply control of coal and the supply control of fuel ammonia would be performed separately, which could result in an imbalance in the heat load. In contrast, if the technology of the present disclosure is applied, the supply control of fuel ammonia is performed in accordance with the supply control of coal, even in coaxial combustion, so the imbalance in the heat load can be suppressed and stable operation is possible.

[0014] The control device may include a receiving unit that receives a switching operation between mono-combustion of coal and mixed combustion of coal and fuel ammonia, and a fuel ammonia control unit that controls the pressure and flow rate of the fuel ammonia by controlling a fuel ammonia regulating valve that adjusts the pressure and flow rate of a fuel ammonia mother pipe and an aperture of a fuel ammonia burner valve that performs ignition operation and extinguishing operation for each of the multiple burner groups. By controlling the pressure of the fuel ammonia when switching between mono-combustion and mixed combustion, mixed combustion can be performed stably.

[0015] The reception unit may receive an operation to switch from mono-fuel combustion to multi-fuel combustion. The fuel ammonia control unit may start flow rate control using a constant value when pressure control operation is completed and predetermined conditions are satisfied. By starting flow rate control using a constant value after pressure control when switching from mono-fuel combustion to multi-fuel combustion, multi-fuel combustion can be performed stably.

[0016] The fuel ammonia control unit may accept an operation to switch between flow rate control using a constant value and flow rate control using a ratio. By being able to switch between flow rate control using a constant value and flow rate control using a ratio, flexible operation becomes possible.

[0017] The reception unit may receive an operation to switch from mixed combustion to mono-fuel combustion. The fuel ammonia control unit may switch from flow rate control to pressure control to sequentially extinguish the plurality of burner groups. By starting pressure control, the switch from mixed combustion to mono-fuel combustion can be performed stably.

[0018] The fuel ammonia control unit may control the pressure of fuel ammonia in any of the following cases: when all of the fuel ammonia burners that ignite and extinguish fuel ammonia in the stages where the coal feeder and mill are operating are not burning; when a runback operation is being performed; when an ignition or extinguishing cycle is being performed; and when a load change is occurring that accompanies start or stop of the coal feeder and mill. By controlling the pressure of fuel ammonia during operation with a changing load, stable mixed combustion can be performed.

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0020] FIG. 1 is a block diagram illustrating the configuration of a control device 1 according to an embodiment. The control device 1 may be applied to, for example, a boiler in a thermal power plant. The control device 1 controls the supply of coal (first fuel or main fuel) and fuel ammonia (second fuel or secondary fuel) as fuel. The coal is used as fuel in the form of pulverized coal that has been dried and pulverized. The fuel ammonia is stored in a liquid state and used as fuel in a vaporized state. The control device 1 includes a control main module 10 (boiler automatic control device) and a control sub-module 20 (fuel ammonia co-firing control device). The control main module 10, the control sub-module 20, and the device group 30 are connected to each other so that they can communicate with each other.

[0021] The control main module 10 is a computer that controls the supply of coal. There are no limitations on the type and configuration of the control main module 10. For example, the control main module 10 may be a combination of a control panel, a terminal such as a personal computer, and a server device.

[0022] The control submodule 20 is a computer that controls the supply of fuel ammonia. There are no limitations on the type and configuration of the control submodule 20. For example, the control submodule 20 may be a combination of a control panel, a terminal such as a personal computer, and a server device.

[0023] The equipment group 30 is a collection of equipment installed in a power plant or the like. The equipment group 30 includes a plurality of burner groups 31, a coal feeder 32, a boiler 33, a turbine / generator 34 (a turbine and a generator), a fuel ammonia shutoff valve 35, a fuel ammonia control valve 36, a fuel ammonia burner valve 37, a fuel ammonia pressure gauge 38, and a fuel ammonia flow meter 39.

[0024] Each of the burner groups 31 includes a plurality of burners. Each burner is a device that mixes fuel with air and burns it. Each burner ignites and extinguishes the fuel. Each burner can use coal and fuel ammonia as fuel. Each burner includes a coal burner that ignites and extinguishes the coal, and a fuel ammonia burner that ignites and extinguishes the fuel ammonia. The coal burner and the fuel ammonia burner can operate independently of each other. The burner groups 31 perform single-fuel or multi-fuel combustion to heat the boiler 33. In the present disclosure, single-fuel combustion refers to combustion using only coal, and multi-fuel combustion refers to combustion using coal and fuel ammonia.

[0025] In each of the plurality of burners, the coal flow path (supply channel, supply port, or supply unit) and the fuel ammonia flow path (supply channel, supply port, or supply unit) may be coaxial. In other words, a cylindrical coal burner and a cylindrical fuel ammonia burner may be concentrically arranged.

[0026] Each of the multiple burner groups 31 is arranged at a position called a stage or burner stage. That is, the multiple burner groups 31 correspond one-to-one to the multiple stages. In one example, pairs of stages facing each other across the boiler 33 in the front-to-back direction (horizontal direction) of the boiler 33 may be divided into three levels in the up-down direction (vertical direction) of the boiler 33, forming a total of six stages (e.g., stage A, stage B, stage C, stage D, stage E, and stage F). In this case, each of the six burner groups 31 is arranged in a corresponding stage. Each of the six burner groups 31 may include four pairs (eight burners), for a total of 48 burners.

[0027] A coal feeder 32 is arranged corresponding to each stage. The coal feeder 32 supplies pulverized coal to the plurality of burner groups 31 via a mill that dries and pulverizes the coal. For example, the coal feeder 32 supplies coal to the plurality of burner groups 31 in accordance with a coal feed amount command C32 that indicates a target value for the coal feed amount obtained from the control main module 10. The coal feeder 32 measures the coal feed amount at each stage and outputs the measured coal feed amount to the control main module 10.

[0028] The boiler 33 is a facility for generating steam, and supplies the steam to the turbine / generator 34.

[0029] The turbine / generator 34 generates electricity using the steam. The turbine / generator 34 generates electricity using, for example, the rotational energy of a steam turbine that receives the steam.

[0030] The fuel ammonia shutoff valve 35 is a valve that shuts off the supply of fuel ammonia in the fuel ammonia mother pipe (the pipe before branching into the pipes of each stage). The fuel ammonia shutoff valve 35 performs a fully open operation or a fully closed operation in accordance with a control signal C35 (open command or close command) acquired from the control submodule 20. The fuel ammonia shutoff valve 35 performs an open operation in accordance with the open command, and performs a close operation in accordance with the close command.

[0031] The fuel ammonia control valve 36 is a valve that adjusts the pressure and flow rate of the fuel ammonia mother pipe. The fuel ammonia control valve 36 adjusts the opening degree in accordance with a control signal C36 (opening degree command) acquired from the control submodule 20. The fuel ammonia control valve 36 operates in accordance with the opening degree command.

[0032] The fuel ammonia burner valve 37 is a valve that controls whether fuel ammonia is supplied to each pair of individual fuel ammonia burners in each stage. The fuel ammonia burner valve 37 performs ignition and extinguishing operations for each of the multiple burner groups 31. The fuel ammonia burner valve 37 performs a full-open operation or a full-close operation in accordance with a control signal C37 (open command or close command) acquired from the control submodule 20. The fuel ammonia burner valve 37 performs an open operation in accordance with an open command and a close operation in accordance with a close command.

[0033] The fuel ammonia pressure gauge 38 measures the pressure of the fuel ammonia mother pipe and transmits the measured pressure D38 to the control submodule 20.

[0034] The fuel ammonia flow meter 39 measures the flow rate of the fuel ammonia and transmits the measured flow rate D39 to the control submodule 20. For example, the fuel ammonia flow meter 39 measures the flow rate of the fuel ammonia mother pipe. The fuel ammonia flow meter 39 may also measure the flow rate of the piping at each stage.

[0035] The control main module 10 has functional elements including a unit master control unit 11, a turbine master control unit 12, a boiler master control unit 13, a feedwater control unit 14, a combustion amount control unit 15, an air control unit 16, a mill master control unit 17, and a coal feeder control unit 18.

[0036] The unit master control unit 11 acquires a unit output command (ULD: Unit Load Demand) related to the output of each unit of the power plant. For example, the unit master control unit 11 may acquire a central load command from a central power dispatching station. The unit master control system may acquire an in-plant output command from within the power plant. In addition, the unit master control system calculates a generator output command (MWD: Mega Watt Demand) based on the unit output command and the load change rate (MW / min).

[0037] The turbine master control unit 12 controls the generator output. For example, the turbine master control unit 12 acquires the generator output of the turbine / generator 34. The turbine master control unit 12 calculates a turbine governor valve opening command by feedback control of the generator output, and controls the turbine governor valve.

[0038] The boiler master control unit 13 controls the main steam pressure. For example, the boiler master control unit 13 acquires the main steam pressure of the boiler 33. The boiler master control unit 13 calculates a main steam pressure set value using a predetermined main steam pressure program. The boiler master control unit 13 calculates a boiler input demand (BID) based on the command from the unit master control unit 11 and the deviation of the main steam pressure.

[0039] The feedwater control unit 14 acquires the feedwater flow rate of the boiler 33. The feedwater control unit 14 calculates a feedwater flow rate set value corresponding to a boiler input command using a water supply program set based on the static characteristics of each unit output. The feedwater control unit 14 calculates the feedwater flow rate command through feedback control and controls the feedwater flow rate of the boiler 33.

[0040] The combustion amount control unit 15 calculates a combustion amount set value corresponding to a boiler input command using a fuel program set based on the static characteristics of each unit output. The combustion amount control unit 15 adds a boiler input rating (BIR) to the combustion amount set value to accommodate output changes. The BIR is a command that adjusts the combustion amount during load increase or decrease in advance of when the load is static, with the aim of improving boiler responsiveness or tracking during output changes. The combustion amount control unit 15 adds a water-fuel ratio command to the combustion amount set value as a correction for various fluid temperature deviations, such as the main steam temperature. The combustion amount control unit 15 calculates a total fuel flow rate command T, which indicates a target value for the total flow rate of fuel supplied to the multiple burner groups 31.

[0041] The air control unit 16 acquires the air flow rates supplied to the plurality of burner groups 31. The air control unit 16 calculates an air flow rate set value using an air program set based on the static characteristics of each unit output. The air control unit 16 multiplies the air flow rate set value by an air-fuel ratio command as a correction based on the oxygen concentration in the exhaust gas. The air control unit 16 calculates the air flow rate command through feedback control and controls the air flow rates supplied to the plurality of burner groups 31.

[0042] The mill master control unit 17 performs coal flow rate control. For example, the mill master control unit 17 acquires a total fuel flow rate command T calculated by the combustion amount control unit 15. The mill master control unit 17 acquires a total fuel ammonia flow rate T39 indicating a measured value of the total flow rate of fuel ammonia from the control submodule 20. The mill master control unit 17 calculates a coal flow rate command indicating a target value of the total coal flow rate using the total fuel flow rate command T and the total fuel ammonia flow rate T39. For example, the mill master control unit 17 subtracts the total fuel ammonia flow rate T39 from the total fuel flow rate command T to calculate the coal flow rate command.

[0043] The mill master control unit 17 acquires and sums the coal feed rates D32 of the coal feeders 32 at each stage that supply fuel to the multiple burner groups 31, thereby calculating a measured value of the total coal feed rate (total coal feed rate for each stage). The mill master control unit 17 calculates a mill master command, which serves as a fuel flow rate command for each stage of the multiple burner groups 31, by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate. For example, the mill master control unit 17 performs a PI calculation (P: proportional action, I: integral action) based on the deviation between the coal flow rate command and the total coal feed rate corresponding to each stage, to calculate the mill master command.

[0044] The coal feeder control unit 18 controls the coal flow rate of each stage. For example, the coal feeder control unit 18 acquires a fuel ammonia flow rate E39 for each stage, which indicates a calculated or measured value of the fuel ammonia flow rate, from the control submodule 20. The coal feeder control unit 18 calculates a coal feed amount command C32 for each of the multiple burner groups 31 based on the mill master command and the calculated or measured value of the fuel ammonia flow rate (the fuel ammonia flow rate E39 for each stage). For example, the coal feeder control unit 18 subtracts the fuel ammonia flow rate corresponding to each stage from the mill master command to calculate the coal feed amount command C32 corresponding to each stage. That is, the coal feed amount command C32 for each stage decreases the coal feed amount in accordance with an increase in the fuel ammonia flow rate for each stage. Furthermore, the coal feed amount command C32 for each stage increases the coal feed amount in accordance with a decrease in the fuel ammonia flow rate for each stage. The coal feeder control unit 18 outputs the coal feed amount command C32 to the coal feeder 32 to control the coal feed amount for each stage.

[0045] The control submodule 20 controls the pressure and flow rate of the fuel ammonia. The control submodule 20 includes a reception unit 21 and a fuel ammonia control unit 22 as functional elements.

[0046] The reception unit 21 receives an operation to switch between single-fuel combustion and dual-fuel combustion. The switching operation is performed, for example, by an operator of the power plant pressing a button.

[0047] Fuel ammonia control unit 22 acquires fuel ammonia flow rate D39 as the flow rate of the mother pipe or the piping of each stage from fuel ammonia flow meter 39. For example, fuel ammonia control unit 22 may acquire total fuel ammonia flow rate T39, which is the flow rate of the mother pipe, from fuel ammonia flow meter 39, as flow rate D39. Fuel ammonia control unit 22 may acquire the flow rates of the piping of each stage from fuel ammonia flow meter 39 as flow rate D39 and acquire the total fuel ammonia flow rate T39 by summing them up. Fuel ammonia control unit 22 transmits total fuel ammonia flow rate T39, which indicates the measured value of the total flow rate of fuel ammonia, to control main module 10.

[0048] Fuel ammonia control unit 22 transmits fuel ammonia flow rate E39 for each stage, which indicates a calculated value or a measured value of the flow rate of fuel ammonia at each stage, to control main module 10. The calculated value of fuel ammonia flow rate E39 for each stage can be calculated based on the pressure D38 of the mother pipe, the injection characteristics of each burner, the number of open pairs of fuel ammonia burner valves 37, etc.

[0049] Fuel ammonia control unit 22 controls various valves related to fuel ammonia. For example, fuel ammonia control unit 22 outputs a control signal C35 (open command or close command) that controls the full opening or full closing operation of fuel ammonia shutoff valve 35. Fuel ammonia control unit 22 outputs a control signal C36 (opening command) that controls the opening degree of fuel ammonia regulating valve 36. Fuel ammonia control unit 22 outputs a control signal C37 (opening command or close command) that controls the full opening or full closing operation of fuel ammonia burner valve 37.

[0050] Fuel ammonia control unit 22 acquires the open / close states of various valves related to fuel ammonia. For example, fuel ammonia control unit 22 acquires the open / close state R35 of fuel ammonia shutoff valve 35. Fuel ammonia control unit 22 acquires the opening degree state R36 of fuel ammonia adjustment valve 36. Fuel ammonia control unit 22 acquires the open / close state R37 of fuel ammonia burner valve 37.

[0051] The fuel ammonia control unit 22 controls the pressure and flow rate of the fuel ammonia by controlling the aperture of the fuel ammonia adjustment valve 36 and the fuel ammonia burner valve 37. For example, the fuel ammonia control unit 22 controls the pressure of the fuel ammonia when switching from mono-fuel combustion to multi-fuel combustion. The fuel ammonia control unit 22 controls the pressure of the fuel ammonia when switching from multi-fuel combustion to mono-fuel combustion.

[0052] When the pressure control operation is completed, the fuel ammonia control unit 22 starts flow rate control using a constant value (hereinafter referred to as "constant value control"). The constant value may be set to the total fuel ammonia flow rate when pressure control is switched to flow rate control as an initial value. The constant value may be set by program flow rate setting of the unit output command, or by manually increasing or decreasing the setting.

[0053] The fuel ammonia control unit 22 may accept an operation to switch between constant value control and flow rate control using a ratio (hereinafter referred to as "ratio control"). For example, the constant value control and ratio control may be manually switched by an operator pressing a button, etc. The ratio is a preset ratio of fuel ammonia in the total fuel (e.g., 20%). In ratio control, the flow rate of fuel ammonia is controlled to a value obtained by multiplying the total fuel flow rate command T by the ratio. Therefore, the ratio can also be said to be a target mixed-combustion ratio setting.

[0054] Furthermore, the fuel ammonia control unit 22 controls the pressure of fuel ammonia in any of the following cases: when all fuel ammonia burners in the stage where the coal feeder 32 (and mill) is operating are not in combustion; when a runback operation is in progress; when an ignition or extinguishing cycle is in progress; or when a load change is in progress that accompanies start-up or stoppage of the coal feeder 32 (and mill). When the pressure control state stabilizes (when all of the conditions in the above cases are not met), the fuel ammonia control unit 22 switches to flow rate control and starts flow rate control using a constant value or a ratio.

[0055] An example of an operation method of the control device 1 will be described with reference to Fig. 2. Fig. 2 is a flowchart showing an example of the operation of the control device 1. In Fig. 2, the explanation will be given on the assumption that the total fuel flow command T has already been calculated by the combustion amount control unit 15.

[0056] In step S1, the mill master control unit 17 acquires the total fuel flow rate command T calculated by the combustion amount control unit 15. The mill master control unit 17 acquires a total fuel ammonia flow rate T39 indicating a measured value of the total flow rate of fuel ammonia from the control submodule 20. The mill master control unit 17 calculates a coal flow rate command indicating a target value of the total coal flow rate using the total fuel flow rate command T and the total fuel ammonia flow rate T39. For example, the mill master control unit 17 subtracts the total fuel ammonia flow rate T39 from the total fuel flow rate command T to calculate the coal flow rate command.

[0057] In step S2, the mill master control unit 17 calculates a measured value of the total coal feed amount (total coal feed amount for each stage) by acquiring and adding up the coal feed amount D32 for each stage corresponding to the multiple burner groups 31. The mill master control unit 17 performs a feedback calculation (PI calculation) based on the deviation between the coal flow rate command and the measured value of the total coal feed amount, and calculates a mill master command, which is a fuel flow rate command for each stage of the multiple burner groups 31.

[0058] In step S3, the coal feeder control unit 18 acquires the calculated value or measured value of the flow rate of fuel ammonia from the control submodule 20. The coal feeder control unit 18 calculates a coal feed amount command C32 indicating a target value of the coal feed amount for each of the multiple burner groups 31, based on the mill master command and the calculated value or measured value of the flow rate of fuel ammonia. For example, the coal feeder control unit 18 subtracts the flow rate of fuel ammonia corresponding to each stage from the mill master command to calculate the coal feed amount command C32 corresponding to each stage. The coal feeder control unit 18 also outputs the coal feed amount command C32 to control the coal feed amount of each stage.

[0059] An example of calculation during multi-combustion will be described with reference to Figures 3 and 4. Figure 3 is a diagram showing an example of the flow of calculation processing for a coal feed rate command. Figure 4 is a diagram showing an example of the flow of calculation processing for fuel ammonia. In this calculation example, six burner groups 31 are arranged corresponding to six stages (stage A, stage B, stage C, stage D, stage E, and stage F). In the following description, it is assumed that five burner groups 31, namely, stages A, B, C, D, and F, are in multi-combustion operation, and one burner group 31 in stage E is stopped (standby).

[0060] The mill master control unit 17 acquires a total fuel flow command a1. In addition, in Fig. 4, the fuel ammonia control unit 22 acquires a total fuel flow command b1. The total fuel flow command a1 and b1 are the same.

[0061] The fuel ammonia control unit 22 calculates the flow rate of fuel ammonia based on the total fuel flow rate command b1 and the ratio setting b2. The ratio setting b2 indicates the co-firing ratio of fuel ammonia. When the co-firing ratio increases, the flow rate of coal during co-firing decreases and the flow rate of fuel ammonia increases. When the co-firing ratio decreases, the flow rate of coal during co-firing increases and the flow rate of fuel ammonia decreases.

[0062] Fuel ammonia control unit 22 corrects the flow rate of fuel ammonia calculated by ratio setting b2 to be based on the calorie of fuel ammonia. The correction value for the calorie basis of fuel ammonia is determined by dividing the calorie value of reference coal by the calorie value of fuel ammonia. Fuel ammonia control unit 22 multiplies the flow rate of fuel ammonia calculated by ratio setting b2 by the correction value for the calorie basis of fuel ammonia to calculate a corrected fuel ammonia flow rate b4.

[0063] Fuel ammonia control unit 22 determines a constant value setting b5 based on a programmed set value or manual set value b6 of the output command and a total fuel ammonia flow rate b7 (total ammonia flow rate). The constant value setting b5 has the total fuel ammonia flow rate b7 at the time of flow rate control as its initial value. The constant value setting b5 may be selectable between a programmed flow rate setting of the output command or a manual setting increase / decrease (programmed set value or manual set value b6 of the output command).

[0064] The ratio setting b2 and the fixed value setting b5 may be set with a restriction b3 based on a coal feed rate lower limit. The restriction b3 based on a coal feed rate lower limit is set so that an increase in the flow rate of fuel ammonia prevents the coal flow rate during mixed combustion from falling below a lower limit. That is, the restriction b3 based on a coal feed rate lower limit limits the upper limit of the flow rate of fuel ammonia. Additionally, the ratio setting b2 and the fixed value setting b5 may be set with a restriction based on a fuel ammonia lower limit. That is, the lower limit of the flow rate of fuel ammonia may also be limited in the same way as the upper limit.

[0065] The fuel ammonia control unit 22 selects a fuel ammonia flow rate command depending on whether the current control is constant value control or ratio control. The constant value control and ratio control may be manually switched between by the operator pressing a button, etc. When the current control is constant value control, the fuel ammonia control unit 22 selects a value based on constant value setting b5 as the fuel ammonia flow rate command. When the current control is ratio control, the fuel ammonia control unit 22 selects a value based on ratio setting b2 as the fuel ammonia flow rate command.

[0066] The fuel ammonia control unit 22 subtracts the total fuel ammonia flow rate b7 from the fuel ammonia flow rate command to calculate the fuel ammonia flow rate for fuel ammonia flow rate control b8.

[0067] The fuel ammonia control unit 22 selects fuel ammonia flow rate control b8 or light-off pressure control b9 depending on whether the current control is pressure control or flow rate control. For the light-off pressure control b9, a pressure setting b12 based on the fuel ammonia mother pipe pressure b10 and the number of open burner valve pairs b11 is used. The fuel ammonia control unit 22 controls the fuel ammonia control valve 36 by pressure control or flow rate control.

[0068] Returning to FIG. 3 , the mill master control unit 17 acquires the total fuel ammonia flow rate a2. The total fuel ammonia flow rate a2 is the same as the total fuel ammonia flow rate b7 in FIG. 4. The mill master control unit 17 corrects the total fuel ammonia flow rate a2 to be based on the calorie of reference coal. Reference coal is a coal fuel that serves as a reference when setting various programs based on the static characteristics of each unit output. The correction value for based on the calorie of reference coal is determined by dividing the calorie value of the fuel ammonia by the calorie value of the reference coal. The mill master control unit 17 multiplies the total fuel ammonia flow rate a2 by the correction value for based on the calorie of reference coal to calculate the corrected total fuel ammonia flow rate a3.

[0069] The mill master control unit 17 subtracts the corrected total fuel ammonia flow rate a3 from the total fuel flow rate command a1 to calculate a coal flow rate command a4.

[0070] The mill master control unit 17 acquires and sums the coal feed amounts D32 of each stage corresponding to the multiple burner groups 31 to calculate a measured value of the total coal feed amount (each stage coal feed amount total a5). The each stage coal feed amount total a5 is corrected by a coal calorie correction signal. The coal calorie correction signal is a correction signal for the calorie ratio between actual coal and reference coal. Actual coal is the coal fuel used during actual plant operation. While the same coal as the reference coal may be used as actual coal, different coals are often used depending on the fuel procurement situation. The mill master control unit 17 multiplies the each stage coal feed amount total a5 by the coal calorie correction signal to calculate the corrected each stage coal feed amount total a6.

[0071] The mill master control unit 17 calculates the deviation between the coal flow rate command a4 and the corrected total coal supply amount a6 for each stage. Here, since five burner groups 31 are in operation, the mill master control unit 17 corrects the calculated deviation by the number of operating units and further calculates a mill master command a8 for each stage by performing a PI calculation.

[0072] The coal feeder control unit 18 acquires the fuel ammonia flow rate a9 of the A stage. The coal feeder control unit 18 corrects the fuel ammonia flow rate a9 of the A stage to be based on the calorie of actual coal. The correction value for the calorie base on actual coal is determined using the calorie value of the fuel ammonia, the calorie value of the reference coal, and a coal calorie correction value (correction value for the calorie ratio between actual coal and reference coal). The coal feeder control unit 18 multiplies the fuel ammonia flow rate a9 of the A stage by the correction value for the calorie base on actual coal, and calculates the corrected fuel ammonia flow rate a10 of the A stage.

[0073] The coal feeder control unit 18 calculates a coal feed rate command for stage A. For example, the coal feeder control unit 18 subtracts the corrected fuel ammonia flow rate a10 for stage A from the mill master command a8 to calculate a coal feed rate command a11 for stage A.

[0074] The coal feeder control unit 18 calculates the coal feed rate command for each of the stages B to F, similar to the calculation of the coal feed rate command a11 for the stage A. That is, the coal feeder control unit 18 calculates the coal feed rate command for each stage based on the mill master command a8 and the fuel ammonia flow rate for each stage corrected to be based on the calorie of actual coal.

[0075] Although the above describes an example of multi-fuel combustion, calculations can be similarly performed for examples of multi-fuel combustion switching (switching from mono-fuel combustion to multi-fuel combustion, or switching from mono-fuel combustion to multi-fuel combustion) or mono-fuel combustion.

[0076] [Switching from Single-fuel Combustion to Dual-fuel Combustion] The process of switching from single-fuel combustion to dual-fuel combustion will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of the operation of the control sub-module 20. The operation of the control main module 10 will not be described in Fig. 5. Fig. 5 is based on the premise that the unit is in single-fuel combustion mode and the unit output is statically determined.

[0077] In step S11, the reception unit 21 receives an operation to switch from mono-fuel combustion to multi-fuel combustion. The switching operation is performed, for example, by an operator of the power plant pressing a button.

[0078] In step S12, fuel ammonia control unit 22 controls fuel ammonia shutoff valve 35. For example, fuel ammonia control unit 22 outputs an open command as control signal C35 for fuel ammonia shutoff valve 35. Fuel ammonia control unit 22 acquires the open / closed state of fuel ammonia shutoff valve 35. Here, fuel ammonia control unit 22 acquires "fully open" as the open / closed state of fuel ammonia shutoff valve 35.

[0079] In step S13, the fuel ammonia control unit 22 controls the pressure of the fuel ammonia. For example, the fuel ammonia control unit 22 outputs an open command as a control signal C37 for the fuel ammonia burner valve 37 of each stage. The fuel ammonia control unit 22 acquires the open / close state of the fuel ammonia burner valve 37 of each stage. Here, the fuel ammonia control unit 22 acquires "fully open" as the open / close state of the fuel ammonia burner valve 37 of each stage. The fuel ammonia control unit 22 sequentially controls the fuel ammonia burner valve 37 of each stage for each pair of stages. The "fully open" state of the fuel ammonia burner valve 37 of each stage means that fuel ammonia has been supplied to the burner pair and ignition has been completed. As described above, by controlling the fuel ammonia burner valve 37, the burner pairs of each stage are ignited sequentially, and ultimately the ignition of the requested plurality of burner groups 31 is completed.

[0080] The fuel ammonia control unit 22 acquires the pressure D38 of the header pipe (the pressure of the header pipe preceding the fuel ammonia burner) from the fuel ammonia pressure gauge 38. The fuel ammonia control unit 22 calculates a fuel ammonia pressure set value based on the number of open pairs of the fuel ammonia burner valves 37 at each stage. The fuel ammonia control unit 22 calculates the flow rate of the fuel ammonia at each stage based on the pressure of the header pipe preceding the fuel ammonia burner, the burner injection characteristics, and the number of open pairs of the fuel ammonia burner valves 37. The flow rate of the fuel ammonia may be a measured value. The fuel ammonia control unit 22 outputs the flow rate of the fuel ammonia at each stage to the control main module 10.

[0081] The fuel ammonia control unit 22 calculates an opening command as a control signal C36 for the fuel ammonia control valve 36 through feedback control, and controls the fuel ammonia control valve 36.

[0082] In step S14, fuel ammonia control unit 22 confirms that the open / close state is "fully open" for all fuel ammonia burner valves 37 for which an open command has been output (to be opened). In other words, fuel ammonia control unit 22 confirms that ignition of fuel ammonia has been completed for all requested burners. Once confirmation is complete, the process proceeds to step S15.

[0083] In step S15, the control of the fuel ammonia control valve 36 by the fuel ammonia control unit 22 automatically switches from pressure control to flow rate control.

[0084] In step S16, the fuel ammonia control unit 22 controls the flow rate of the fuel ammonia. For example, the fuel ammonia control unit 22 starts constant value control of the fuel ammonia.

[0085] Fuel ammonia control unit 22 obtains total fuel flow rate command T from control main module 10. Fuel ammonia control unit 22 obtains total fuel ammonia flow rate T39, which is the flow rate of the mother pipe, from fuel ammonia flow meter 39, as flow rate D39. Fuel ammonia control unit 22 may obtain, as flow rate D39, the flow rates of the piping of each stage from fuel ammonia flow meter 39 and add them up to obtain total fuel ammonia flow rate T39. Fuel ammonia control unit 22 outputs total fuel ammonia flow rate T39 to control main module 10.

[0086] The fuel ammonia control unit 22 may calculate and output a constant flow rate command by program setting using the unit output command as an index. The fuel ammonia control unit 22 may output the constant flow rate command in response to an operator pressing an operation button.

[0087] The constant value control and the ratio control may be manually switched by the operator pressing a button, etc. Here, the description will be made assuming that the constant value control is switched to the ratio control.

[0088] In the ratio control, the fuel ammonia control unit 22 performs flow rate control by feedback control of a fuel ammonia flow rate command calculated based on a target mixed-combustion ratio setting. For example, the fuel ammonia control unit 22 calculates and outputs a flow rate command based on the total fuel ammonia flow rate and the target mixed-combustion ratio setting. When the target mixed-combustion ratio is achieved, the switch from mono-fuel combustion to mixed-combustion is completed.

[0089] [Switching from dual combustion to mono-fuel combustion] The process of switching from dual combustion to mono-fuel combustion will be described with reference to Fig. 6. Fig. 6 is a diagram showing another example of the operation of the control sub-module 20. The operation of the control main module 10 will not be described in Fig. 6. Fig. 6 assumes that dual combustion is in operation and the unit output is statically determined.

[0090] In step S21, the reception unit 21 receives an operation to switch from dual-fuel combustion to mono-fuel combustion. The switching operation is performed, for example, by an operator of the power plant pressing a button.

[0091] In step S22, the control of the fuel ammonia control valve 36 by the fuel ammonia control unit 22 automatically switches from flow rate control to pressure control.

[0092] In step S23, the fuel ammonia control unit 22 controls the pressure of the fuel ammonia. For example, the fuel ammonia control unit 22 outputs a command to close the fuel ammonia burner valve 37 of each stage. The fuel ammonia control unit 22 acquires the open / close state of the fuel ammonia burner valve 37 of each stage. Here, the fuel ammonia control unit 22 acquires "fully closed" as the open / close state of the fuel ammonia burner valve 37 of each stage. The fuel ammonia control unit 22 sequentially controls the fuel ammonia burner valve 37 of each stage for each pair of stages. The "fully closed" state of the fuel ammonia burner valve 37 of each stage means that fuel ammonia is not supplied to the burner pair and that extinguishing has been completed. As described above, by controlling the fuel ammonia burner valve 37, the burner pairs of each stage are sequentially extinguished, and finally, the extinguishing of the requested plurality of burner groups 31 is completed. That is, the fuel ammonia control unit 22 switches from flow rate control to pressure control to sequentially extinguish the plurality of burner groups 31.

[0093] The fuel ammonia control unit 22 acquires the pressure D38 of the header pipe (the pressure of the header pipe preceding the fuel ammonia burner) from the fuel ammonia pressure gauge 38. The fuel ammonia control unit 22 calculates a fuel ammonia pressure set value based on the number of open pairs of the fuel ammonia burner valves 37 at each stage. The fuel ammonia control unit 22 calculates the flow rate of the fuel ammonia at each stage based on the pressure of the header pipe preceding the fuel ammonia burner, the burner injection characteristics, and the number of open pairs of the fuel ammonia burner valves 37. The flow rate of the fuel ammonia may be a measured value. The fuel ammonia control unit 22 outputs the flow rate of the fuel ammonia at each stage to the control main module 10.

[0094] The fuel ammonia control unit 22 calculates an opening command as a control signal C36 for the fuel ammonia control valve 36 through feedback control, and controls the fuel ammonia control valve 36.

[0095] Fuel ammonia control unit 22 acquires, as flow rate D39, total fuel ammonia flow rate T39, which is the flow rate of the mother pipe, from fuel ammonia flow meter 39. Fuel ammonia control unit 22 may acquire, as flow rate D39, the flow rates of the piping of each stage from fuel ammonia flow meter 39 and add them up to acquire total fuel ammonia flow rate T39. Fuel ammonia control unit 22 outputs the total fuel ammonia flow rate to control main module 10.

[0096] In step S24, fuel ammonia control unit 22 confirms that the open / close state of all fuel ammonia burner valves 37 for which a close command has been output (to be closed) is "fully closed." In other words, fuel ammonia control unit 22 confirms that extinguishing of fuel ammonia has been completed for all requested burners. Once confirmation is complete, the process proceeds to step S25.

[0097] In step S25, the fuel ammonia control unit 22 controls the fuel ammonia regulating valve 36. For example, the fuel ammonia control unit 22 outputs a command to fully close the fuel ammonia regulating valve 36. The fuel ammonia control unit 22 acquires the open / close state of the fuel ammonia regulating valve 36. Here, the fuel ammonia control unit 22 acquires "fully closed" as the open / close state of the fuel ammonia regulating valve 36.

[0098] In step S26, fuel ammonia control unit 22 controls fuel ammonia shutoff valve 35. For example, fuel ammonia control unit 22 outputs a command to close fuel ammonia shutoff valve 35. Fuel ammonia control unit 22 acquires the open / closed state of fuel ammonia shutoff valve 35. Here, fuel ammonia control unit 22 acquires "fully closed" as the open / closed state of fuel ammonia shutoff valve 35. When fuel ammonia shutoff valve 35 is fully closed, the switch from dual combustion to mono-fuel combustion is completed.

[0099] [Output Change or Runback] Processing when an output change or runback occurs will be described with reference to Figure 7. Runback is a control that, when an abnormality occurs in a major device, rapidly narrows the boiler input command toward a target load (runback target value) that allows continued operation with the remaining healthy devices. Figure 7 is a diagram showing yet another example of the operation of the control submodule 20. In Figure 7, a description of the operation of the control main module 10 will be omitted. In Figure 7, it is assumed that dual combustion is being performed and the unit output is statically determined.

[0100] In step S31, the control submodule 20 allocates processing depending on the content of the output change command or whether or not runback has occurred. For example, when an output change command involving additional start or stop of the coal feeder 32 (and mill) is acquired, the processing proceeds to step S32. During an output change, pressure control in step S32 is performed until start or stop of the coal feeder 32 (and mill) is completed, fuel ammonia ignition or extinguishing of the burner is completed, and the target load is reached. Depending on the plant, coal may be re-ignited first, and then fuel ammonia ignition of the burner may be performed after the target load is reached. Depending on the plant, fuel ammonia ignition may be performed in parallel with re-ignition of coal while the load is increased. Depending on the plant, fuel ammonia ignition may be performed in parallel with re-ignition of coal while the load is decreased.

[0101] If an output change command that does not involve additional start or stop of the coal feeder 32 (and the mill) is acquired, the process proceeds to step S35. In step S35, flow rate control is performed in accordance with the output change command.

[0102] If runback occurs, the process proceeds to step S32 (pressure control is started). When runback occurs, the fuel ammonia in the stage related to the stop of the coal feeder 32 or the like is extinguished.

[0103] If runback has not occurred, the process proceeds to step S35, where normal flow control continues.

[0104] In step S32, the fuel ammonia control unit 22 controls the pressure of the fuel ammonia. For example, the fuel ammonia control unit 22 outputs an open command or a close command as a control signal C37 for the fuel ammonia burner valve 37 of each stage. The fuel ammonia control unit 22 acquires the open / close state of the fuel ammonia burner valve 37 of each stage. Here, the fuel ammonia control unit 22 acquires "fully open" or "fully closed" as the open / close state of the fuel ammonia burner valve 37 of each stage. When the output changes, the fuel ammonia control unit 22 sequentially controls the fuel ammonia burner valve 37 of each stage for each pair of stages. When a runback occurs, the fuel ammonia of the stage related to the stop of the coal feeder 32, etc. is immediately extinguished.

[0105] The fuel ammonia control unit 22 acquires the pressure D38 of the header pipe (the pressure of the header pipe preceding the fuel ammonia burner) from the fuel ammonia pressure gauge 38. The fuel ammonia control unit 22 calculates a fuel ammonia pressure set value based on the number of open pairs of the fuel ammonia burner valves 37 at each stage. The fuel ammonia control unit 22 calculates the flow rate of the fuel ammonia at each stage based on the pressure of the header pipe preceding the fuel ammonia burner, the burner injection characteristics, and the number of open pairs of the fuel ammonia burner valves 37. The flow rate of the fuel ammonia may be a measured value. The fuel ammonia control unit 22 outputs the flow rate of the fuel ammonia at each stage to the control main module 10.

[0106] The fuel ammonia control unit 22 calculates an opening command as a control signal C36 for the fuel ammonia control valve 36 through feedback control, and controls the fuel ammonia control valve 36.

[0107] In step S33, fuel ammonia control unit 22 confirms that the open / close state is "fully open" for all fuel ammonia burner valves 37 to which an open command has been output (to be opened). In other words, fuel ammonia control unit 22 confirms that ignition of fuel ammonia has been completed for all requested burners. Alternatively, fuel ammonia control unit 22 confirms that the open / close state is "fully closed" for all fuel ammonia burner valves 37 to which a close command has been output (to be closed). In other words, fuel ammonia control unit 22 confirms that extinguishing of fuel ammonia has been completed for all requested burners. Once confirmation is complete, the process proceeds to step S34.

[0108] In step S34, the control of the fuel ammonia control valve 36 by the fuel ammonia control unit 22 is automatically switched from pressure control to flow rate control. For example, when the output changes, the control is switched after the target load is reached and ignition or extinguishing of coal and fuel ammonia is all completed and stabilized. Alternatively, when runback occurs, the control is switched after the runback is reset and stabilized.

[0109] In step S35, fuel ammonia control unit 22 performs flow rate control of fuel ammonia. For example, when pressure control is switched to flow rate control in step S34, fuel ammonia control unit 22 starts constant value control of fuel ammonia. When flow rate control is to be continued, constant value flow rate control or ratio flow rate control is continued.

[0110] Fuel ammonia control unit 22 obtains total fuel flow rate command T from control main module 10. Fuel ammonia control unit 22 obtains total fuel ammonia flow rate T39, which is the flow rate of the mother pipe, from fuel ammonia flow meter 39, as flow rate D39. Fuel ammonia control unit 22 may obtain, as flow rate D39, the flow rates of the piping of each stage from fuel ammonia flow meter 39 and add them up to obtain total fuel ammonia flow rate T39. Fuel ammonia control unit 22 outputs the total fuel ammonia flow rate to control main module 10.

[0111] The fuel ammonia control unit 22 may calculate and output a constant flow rate command by program setting using the unit output command as an index. The fuel ammonia control unit 22 may output the constant flow rate command in response to an operator pressing an operation button.

[0112] The constant value control and the ratio control may be manually switched by the operator pressing a button, etc. Here, the description will be made assuming that the constant value control is switched to the ratio control.

[0113] In the ratio control, the fuel ammonia control unit 22 performs flow rate control by feedback control of a fuel ammonia flow rate command calculated based on a target mixing ratio setting. For example, the fuel ammonia control unit 22 calculates and outputs a flow rate command based on the total fuel ammonia flow rate and the target mixing ratio setting.

[0114] [Hardware Configuration] Fig. 8 is a diagram showing an example of a hardware configuration related to the control device 1. Fig. 8 shows a computer 100 that functions as the control main module 10 or the control sub-module 20. The computer 100 has a processor 101, a main memory unit 102, an auxiliary memory unit 103, a communication control unit 104, an input device 105, and an output device 106. The control main module 10 or the control sub-module 20 is configured by one or more computers 100 that are configured by these pieces of hardware and software such as programs.

[0115] When the control main module 10 or the control sub-module 20 is configured by a plurality of computers 100, these computers 100 may be connected locally or via a communication network such as the Internet or an intranet. This connection logically constructs a single control main module 10 or control sub-module 20.

[0116] The processor 101 is a CPU (Central Processing Unit) that executes an operating system, application programs, etc. The main memory 102 is composed of a ROM (Read Only Memory) and a RAM (Random Access Memory). The auxiliary memory 103 is a storage medium composed of a hard disk, flash memory, etc. The auxiliary memory 103 generally stores a larger amount of data than the main memory 102. The communication control unit 104 is composed of a network card or a wireless communication module. At least a portion of the communication function with other devices in the control main module 10 or the control sub-module 20 may be realized by the communication control unit 104. The input device 105 is composed of a keyboard, a mouse, a touch panel, a microphone for voice input, etc. The output device 106 is composed of a display, a printer, etc.

[0117] The auxiliary storage unit 103 stores in advance the program 110 and data necessary for processing. The program 110 causes the computer 100 to execute each functional element of the control main module 10 or the control submodule 20. The program 110 causes, for example, processing related to the above-mentioned control method to be executed in the computer 100. For example, the program 110 is read by the processor 101 or the main storage unit 102, and causes at least one of the processor 101, the main storage unit 102, the auxiliary storage unit 103, the communication control unit 104, the input device 105, and the output device 106 to operate. For example, the program 110 reads and writes data from and to the main storage unit 102 and the auxiliary storage unit 103.

[0118] The program 110 may be provided in the form of being recorded on a tangible storage medium such as a CD-ROM, a DVD-ROM, a semiconductor memory, etc. The program 110 may also be provided as a data signal via a communication network.

[0119] As described above, a control device 1 according to one aspect of the present disclosure controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups 31, each including a plurality of burners. The control device 1 includes: a mill master control unit 17 that calculates a coal flow rate command that indicates a target value of the total coal flow rate using a total fuel flow rate command T that indicates a target value of the total fuel flow rate and a total fuel ammonia flow rate T39 that indicates a measured value of the total fuel ammonia flow rate, and calculates a mill master command that indicates a fuel manipulation amount for each of the plurality of burner groups 31 by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate; and a coal feeder control unit 18 that calculates a coal feed rate command C32 that indicates a target value of the coal feed rate for each of the plurality of burner groups 31 based on the mill master command and the calculated or measured value of the fuel ammonia flow rate (fuel ammonia flow rate E39 for each stage), and outputs the coal feed rate command C32.

[0120] A control method according to one aspect of the present disclosure controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups 31, each including a plurality of burners. The control method includes the steps of: calculating a coal flow rate command indicating a target value of the total coal flow rate, using a total fuel flow rate command T indicating a target value of the total fuel flow rate, and a total fuel ammonia flow rate T39 indicating a measured value of the total fuel ammonia flow rate; calculating a mill master command indicating a fuel manipulation amount for each of the plurality of burner groups 31 by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate; and calculating a coal feed rate command C32 indicating a target value of the coal feed rate for each of the plurality of burner groups 31, based on the mill master command and the calculated or measured value of the fuel ammonia flow rate (fuel ammonia flow rate E39 for each stage), and outputting the coal feed rate command C32.

[0121] In a control device and control method according to an aspect of the present disclosure, a coal flow rate command is calculated from a total fuel flow rate command T and a total fuel ammonia flow rate T39, a mill master command is calculated by feedback calculation based on the deviation between the coal flow rate command and a measured value of the total coal feed rate, and a coal feed rate command C32 is calculated for each of a plurality of burner groups 31 from the mill master command and the calculated or measured value of the fuel ammonia flow rate, and the coal feed rate command C32 is output. In a control device and control method according to an aspect of the present disclosure, the coal feed rate is controlled by outputting a coal feed rate command C32 that causes the coal feed rate of each stage to follow an increase or decrease in the fuel ammonia flow rate of each stage. That is, the coal feed rate command C32 of each stage decreases the coal feed rate in accordance with an increase in the fuel ammonia flow rate of each stage. Furthermore, the coal feed rate command C32 of each stage increases the coal feed rate in accordance with a decrease in the fuel ammonia flow rate of each stage. For example, even if differences in the flow rate of fuel ammonia at each stage occur due to the ignition or extinguishing of the fuel ammonia burner when switching between mono-fuel and multi-fuel combustion, automatic control is possible while maintaining uniform heat loads at each stage and stable combustion. As a result, mono-fuel and multi-fuel combustion can be performed stably. In addition, existing equipment (such as control devices for mono-fuel coal combustion) can be utilized, and the scope of modifications can be limited to the part related to fuel ammonia control.

[0122] In each of the multiple burners, the coal flow path and the fuel ammonia flow path are coaxial. The coal flow path and the fuel ammonia flow path are coaxial, and coaxial combustion is performed in which the coal and fuel ammonia are burned coaxially. If coaxial combustion were performed without applying the technology of the present disclosure, for example, the supply control of coal and the supply control of fuel ammonia would be performed separately, which could result in an imbalance in the heat load. In contrast, when the technology of the present disclosure is applied, the supply control of fuel ammonia is performed in accordance with the supply control of coal, even in coaxial combustion, so the imbalance in the heat load can be suppressed and stable operation is possible.

[0123] The control device 1 includes a reception unit 21 that receives a switching operation between mono-combustion of coal and mixed combustion of coal and fuel ammonia, and a fuel ammonia control unit 22 that controls the pressure and flow rate of the fuel ammonia by controlling a fuel ammonia adjustment valve 36 that adjusts the pressure and flow rate of a fuel ammonia mother pipe and an aperture of a fuel ammonia burner valve 37 that performs ignition and extinguishing operations for each of the multiple burner groups 31. By controlling the pressure of the fuel ammonia when switching between mono-combustion and mixed combustion, mixed combustion can be performed stably.

[0124] The reception unit 21 receives an operation to switch from mono-fuel combustion to multi-fuel combustion. The fuel ammonia control unit 22 starts flow rate control using a constant value when the pressure control operation is completed and predetermined conditions are satisfied. By starting flow rate control using a constant value after the pressure control when switching from mono-fuel combustion to multi-fuel combustion, multi-fuel combustion can be performed stably.

[0125] The fuel ammonia control unit 22 accepts an operation to switch between flow rate control using a constant value and flow rate control using a ratio. By being able to switch between flow rate control using a constant value and flow rate control using a ratio, flexible operation becomes possible.

[0126] The reception unit 21 receives an operation to switch from mixed combustion to mono-fuel combustion. The fuel ammonia control unit 22 switches from flow rate control to pressure control and sequentially extinguishes the plurality of burner groups 31. By starting pressure control, the switch from mixed combustion to mono-fuel combustion can be performed stably.

[0127] The fuel ammonia control unit 22 controls the pressure of fuel ammonia in any of the following cases: when all of the fuel ammonia burners that ignite and extinguish fuel ammonia in the stages where the coal feeder 32 and the mill are operating are not burning; when a runback operation is in progress; when an ignition or extinguishing cycle is in progress; or when a load change occurs that accompanies the start or stop of the coal feeder 32 and the mill. By controlling the pressure of fuel ammonia during operation with a changing load, mixed combustion can be performed stably.

[0128] The present disclosure is not necessarily limited to the above-described embodiment, and various modifications are possible within the scope of the present disclosure. For example, the fuel ammonia may be controlled to follow the BIR from the boiler input command, and the coal may be controlled to a fixed value.

[0129] [Note] In the future, many projects are expected to transition from coal-fired mono-combustion to co-firing of coal and fuel ammonia in Japan and overseas. The control device and control method disclosed herein can be widely applied to such fuel conversion projects.

[0130] The control device and control method disclosed herein maintains thermal load equality during co-firing of coal and fuel ammonia, as well as during mono-firing of coal, enabling more stable operation. Therefore, the control device and control method disclosed herein contribute to Target 7.a of the Sustainable Development Goals (SDGs) led by the United Nations.

[0131] Target 7.a is "By 2030, enhance international cooperation to facilitate access to clean energy research and technology, including renewable energy, energy efficiency and advanced and cleaner fossil-fuel technology, and promote investment in energy infrastructure and clean energy technology."

[0132] The gist of the present disclosure is as follows. [1] A control device that controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups each including a plurality of burners, the control device comprising: a mill master control unit that calculates a coal flow rate command that indicates a target value of the total coal flow rate using a total fuel flow rate command that indicates a target value of the total fuel flow rate and a total fuel ammonia flow rate that indicates a measured value of the total fuel ammonia flow rate, and calculates a mill master command that indicates a manipulated variable of the fuel for each of the plurality of burner groups by feedback calculation based on a deviation between the coal flow rate command and the measured value of the total coal feed rate; and a coal feeder control unit that calculates a coal feed rate command that indicates a target value of the coal feed rate for each of the plurality of burner groups based on the mill master command and the calculated value or the measured value of the fuel ammonia flow rate, and outputs the coal feed rate command. [2] The control device according to [1], wherein the coal flow path and the fuel ammonia flow path are coaxial in each of the plurality of burners. [3] The control device according to [1] or [2], comprising: a reception unit that receives a switching operation between the mono-combustion of coal and mixed-combustion of the coal and the fuel ammonia; and a fuel ammonia control unit that controls the pressure and flow rate of the fuel ammonia by controlling a fuel ammonia control valve that adjusts the pressure and flow rate of the fuel ammonia mother pipe and an aperture of a fuel ammonia burner valve that performs ignition operation and extinguishing operation for each of the plurality of burner groups. [4] The control device according to [3], wherein the reception unit receives a switching operation from the mono-combustion to the mixed-combustion, and the fuel ammonia control unit starts flow rate control using a constant value when the pressure control operation is completed and a predetermined condition is satisfied. [5] The control device according to [4], wherein the fuel ammonia control unit receives an operation to switch between flow rate control using the constant value and flow rate control using a ratio. [6] The control device according to [4], wherein the reception unit receives a switching operation from the mixed-combustion to the mono-combustion, and the fuel ammonia control unit switches from the flow rate control to the pressure control to sequentially extinguish the plurality of burner groups.[7] The control device according to any of [3] to [6], wherein the fuel ammonia control unit controls the pressure of the fuel ammonia in any of the following cases: all fuel ammonia burners that ignite and extinguish the fuel ammonia in a stage where a coal feeder and a mill are operating are not in combustion; runback operation is being performed; an ignition or extinguishing cycle is being performed; or a load change that accompanies start-up or stop of the coal feeder and the mill is being performed. [8] A control method for controlling the supply of fuel containing coal and fuel ammonia to a plurality of burner groups, each of which includes a plurality of burners, comprising: a step of calculating a coal flow rate command indicating a target value of the total coal flow rate, using a total fuel flow rate command indicating a target value of the total fuel flow rate, and a total fuel ammonia flow rate indicating a measured value of the total fuel ammonia flow rate; a step of calculating a mill master command indicating an operation amount of the fuel for each of the plurality of burner groups by feedback calculation based on a deviation between the coal flow rate command and the measured value of the total coal feed rate; and a step of calculating a coal feed rate command indicating a target value of the coal feed rate for each of the plurality of burner groups, based on the mill master command and the calculated value or the measured value of the fuel ammonia flow rate, and outputting the coal feed rate command.

[0133] REFERENCE SIGNS LIST 1 control device 10 control main module 11 unit master control unit 12 turbine master control unit 13 boiler master control unit 14 water supply control unit 15 combustion amount control unit 16 air control unit 17 mill master control unit 18 coal feeder control unit 20 control sub-module 21 reception unit 22 fuel ammonia control unit 30 device group 31 burner group 32 coal feeder 33 boiler 34 turbine / generator 35 fuel ammonia shutoff valve 36 fuel ammonia control valve 37 fuel ammonia burner valve 38 fuel ammonia pressure gauge 39 fuel ammonia flow meter

Claims

1. A control device that controls the supply of fuel containing coal and fuel ammonia to a plurality of burner groups, each of which contains a plurality of burners, comprising: a mill master control unit that calculates a coal flow rate command that indicates a target value for the total coal flow rate using a total fuel flow rate command that indicates a target value for the total flow rate of the fuel and a total fuel ammonia flow rate that indicates a measured value for the total fuel ammonia flow rate, and calculates a mill master command that indicates an operation amount for the fuel for each of the plurality of burner groups by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate; and a coal feeder control unit that calculates a coal feed rate command that indicates a target value for the coal feed rate for each of the plurality of burner groups based on the mill master command and the calculated value or the measured value of the fuel ammonia flow rate, and outputs the coal feed rate command.

2. The control device according to claim 1, wherein in each of said plurality of burners, the coal flow path and the fuel ammonia flow path are coaxial.

3. The control device according to claim 1, comprising: a reception unit that receives a switching operation between the single-fuel combustion of coal and the mixed combustion of coal and the fuel ammonia; and a fuel ammonia control unit that controls the pressure and flow rate of the fuel ammonia by controlling a fuel ammonia regulating valve that adjusts the pressure and flow rate of the fuel ammonia mother pipe and an aperture of a fuel ammonia burner valve that performs ignition and extinguishing operations for each of the plurality of burner groups.

4. The control device according to claim 3, wherein the reception unit receives an operation to switch from the mono-fuel combustion to the multi-fuel combustion, and the fuel ammonia control unit starts flow rate control using a constant value when the pressure control operation is completed and predetermined conditions are satisfied.

5. The control device according to claim 4, wherein the reception unit receives an operation to switch from the mixed combustion to the mono-fuel combustion, and the fuel ammonia control unit switches from the flow rate control to the pressure control, and sequentially extinguishes the plurality of burner groups.

6. The control device according to claim 4, wherein the fuel ammonia control unit accepts an operation to switch between flow rate control using the constant value and flow rate control using a ratio.

7. The control device according to claim 3, wherein the fuel ammonia control unit controls the pressure of the fuel ammonia in any of the following cases: when all of the fuel ammonia burners that ignite and extinguish the fuel ammonia at the stage where the coal feeder and the mill are operating are not in combustion; when a runback operation is being performed; when an ignition or extinguishing cycle is being performed; and when a load change that accompanies start-up or stop of the coal feeder and the mill is being performed.

8. A control method for controlling the supply of fuel containing coal and fuel ammonia to a plurality of burner groups, each of which includes a plurality of burners, comprising: a step of calculating a coal flow rate command indicating a target value of the total coal flow rate, using a total fuel flow rate command indicating a target value of the total fuel flow rate, and a total fuel ammonia flow rate indicating a measured value of the total fuel ammonia flow rate; a step of calculating a mill master command indicating an operation amount of the fuel for each of the plurality of burner groups by feedback calculation based on the deviation between the coal flow rate command and the measured value of the total coal feed rate; and a step of calculating a coal feed rate command indicating a target value of the coal feed rate for each of the plurality of burner groups, based on the mill master command and the calculated value or the measured value of the fuel ammonia flow rate, and outputting the coal feed rate command.

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