Boiler, power generation equipment and control method of boiler

Abstract

To accelerate a load change speed of a boiler when performing a load change operation for changing a load of the boiler for combusting both solid fuel and ammonia fuel by a furnace.SOLUTION: In a control method of a boiler, the boiler has a solid fuel burner for forming a flame by using solid fuel in a furnace, a solid fuel adjustment part for adjusting a supply quantity of the solid fuel which is supplied to the solid fuel burner, an ammonia fuel burner for forming a flame by using ammonia fuel in the furnace, and an ammonia fuel adjustment part for adjusting a supply quantity of the ammonia fuel which is supplied to the ammonia fuel burner. The control method also comprises a control step for controlling the solid fuel adjustment part and the ammonia fuel adjustment part, and when performing a load increase operation for increasing a load of the boiler, the control step S102 controls the ammonia fuel adjustment part so that the supply quantity of the ammonia fuel which is supplied to the ammonia fuel burner is increased in an operation period from a start of the load increase operation up to a finish thereof.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a boiler, a power generation facility, and a method for controlling a boiler. [Background technology]

[0002] Conventionally, a boiler that performs combined combustion of pulverized coal and ammonia has been known (see, for example, Patent Document 1). When performing a load increasing operation to increase the load, the boiler disclosed in Patent Document 1 supplies only fuel other than ammonia fuel to the burner section at the start of the load increasing operation, and then starts supplying ammonia fuel when the air ratio of the burner section and the temperature inside the furnace satisfy the judgment conditions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-155820 Summary of the Invention [Problem to be solved by the invention]

[0004] When ammonia fuel is mixed with a solid fuel such as pulverized coal, if the mixed-combustion ratio of ammonia fuel (the ratio of the heat input of ammonia fuel to the total heat input of fuel) is lower than the mixed-combustion ratio of solid fuel (the ratio of the heat input of solid fuel to the total heat input of fuel), the solid fuel becomes the main fuel. In this case, when changing the load on the boiler, it is common to change the amount of heat input to the boiler by changing the amount of solid fuel supplied, which is the main fuel. Therefore, the rate of change of the load on the boiler is limited by the rate of change of the amount of solid fuel supplied to the boiler.

[0005] On the other hand, it is known that ammonia fuel (especially liquid ammonia) has a characteristic that it is easier to change the supply amount when comparing ammonia fuel, which is liquid or gaseous, with solid fuel. In Patent Document 1, ammonia fuel is not supplied to the burner at the start of the load increase operation, and only other fuels such as pulverized coal are supplied, so there is room for improvement in order to increase the load change speed of the boiler.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a boiler, a power generation facility, and a boiler control method that are capable of increasing the load change rate of a boiler when performing a load change operation to change the load of a boiler that burns both solid fuel and ammonia fuel in a furnace. [Means for solving the problem]

[0007] In order to solve the above problems, a boiler, a power generation facility, and a boiler control method according to one embodiment of the present disclosure employ the following measures. A boiler according to one aspect of the present disclosure includes a solid fuel burner that injects solid fuel into a furnace for combustion, a solid fuel adjustment unit that adjusts the supply amount of the solid fuel supplied to the solid fuel burner, an ammonia fuel burner that injects ammonia fuel into the furnace for combustion, an ammonia fuel adjustment unit that adjusts the supply amount of the ammonia fuel supplied to the ammonia fuel burner, and a control unit that controls the solid fuel adjustment unit and the ammonia fuel adjustment unit, wherein when performing a load changing operation to change the load of the boiler, the control unit controls the ammonia fuel adjustment unit to change the supply amount of the ammonia fuel supplied to the ammonia fuel burner during an operation period from the start of the load changing operation to the completion of the load changing operation.

[0008] In a boiler control method according to one aspect of the present disclosure, the boiler has a solid fuel burner that forms a flame in a furnace using solid fuel, a solid fuel adjustment unit that adjusts the supply amount of the solid fuel supplied to the solid fuel burner, an ammonia fuel burner that forms a flame in the furnace using ammonia fuel, and an ammonia fuel adjustment unit that adjusts the supply amount of the ammonia fuel supplied to the ammonia fuel burner, and includes a control step of controlling the solid fuel adjustment unit and the ammonia fuel adjustment unit, wherein the control step controls the ammonia fuel adjustment unit to change the supply amount of the ammonia fuel supplied to the ammonia fuel burner during an operation period from the start of the load change operation to the completion of the load change operation when a load change operation that changes the load of the boiler is performed. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a boiler, a power generation facility, and a boiler control method that are capable of increasing the load change rate of a boiler when performing a load change operation to change the load of a boiler that burns both solid fuel and ammonia fuel in a furnace. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram showing a boiler according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a front view of the combustion burner shown in FIG. [Diagram 3] FIG. 2 is a cross-sectional view of an ammonia-fuel burner included in the combustion burner shown in FIG. [Figure 4] FIG. 2 is a cross-sectional view of a pulverized fuel burner of the combustion burner of the boiler shown in FIG. [Diagram 5] 4 is a flowchart showing a boiler control method according to the first embodiment of the present disclosure. [Figure 6] 1 is a graph showing changes in boiler load over time. [Figure 7] 4 is a graph showing the change over time in the supply amount of pulverized fuel. [Figure 8]4 is a graph showing the change over time in the supply amount of ammonia fuel. [Figure 9] 6 is a flowchart showing a boiler control method according to a second embodiment of the present disclosure. [Figure 10] 4 is a graph showing the change over time in the supply amount of pulverized fuel. [Figure 11] 4 is a graph showing the change over time in the supply amount of ammonia fuel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [First embodiment] Hereinafter, a boiler 10 according to a first embodiment of the present disclosure will be described with reference to the drawings. The boiler 10 according to the present embodiment is a device that burns pulverized fuel (solid fuel) and ammonia fuel using a combustion burner and recovers heat generated by the combustion.

[0012] Fig. 1 is a schematic diagram showing a boiler 10 according to a first embodiment of the present disclosure. As shown in Fig. 1, the boiler 10 of this embodiment has a furnace 11, a combustion device 12, and a flue 13. The furnace 11 has a hollow rectangular cylindrical shape and is installed along the vertical direction. The combustion device 12 is provided at the bottom of the furnace wall that constitutes this furnace 11.

[0013] The combustion device 12 has a plurality of combustion burners 100A, 100B, 100C, 100D, and 100E attached to the furnace wall. In this embodiment, the combustion burners 100A, 100B, 100C, 100D, and 100E are arranged in five sets (five stages) along the vertical direction, with four burners arranged at equal intervals along the circumferential direction around the central axis of the vertical direction along which the furnace 11 extends. Although five sets are used here, six sets or any other number of sets may be used.

[0014] Each of the combustion burners 100A, 100B, 100C, 100D, and 100E is connected to a pulverizer 31, 32, 33, 34, and 35 via a pulverizer fuel supply pipe 26, 27, 28, 29, and 30. The pulverizer 31, 32, 33, 34, and 35 pulverize solid carbonaceous fuel such as coal into pulverized fuel, and supply the pulverized fuel together with a carrier gas such as air to the pulverized fuel supply pipe 26, 27, 28, 29, and 30. The pulverized fuel is supplied from the pulverized fuel supply pipe 26, 27, 28, 29, and 30 to the combustion burners 100A, 100B, 100C, 100D, and 100E.

[0015] The pulverizers 31, 32, 33, 34, and 35 are connected to flow rate adjustment units (solid fuel adjustment units) 31a, 32a, 33a, 34a, and 35a via solid fuel supply pipes 31b, 32b, 33b, 34b, and 35b, respectively. The supply amount of pulverized fuel supplied to the combustion burners 100A, 100B, 100C, 100D, and 100E via the pulverized fuel supply pipes 26, 27, 28, 29, and 30 is controlled by adjusting the amount of solid carbonaceous fuel supplied to the pulverizers 31, 32, 33, 34, and 35 by the flow rate adjustment units (solid fuel adjustment units) 31a, 32a, 33a, 34a, and 35a.

[0016] 1 shows an example in which a belt conveyor is applied to the flow rate adjusting unit (solid fuel adjusting unit) 31a, 32a, 33a, 34a, 35a. For example, the amount of solid carbonaceous fuel supplied to the pulverizers 31, 32, 33, 34, 35 is adjusted by the belt moving speed of the belt conveyor. Here, since unpulverized solid carbonaceous fuel remains inside the pulverizers 31, 32, 33, 34, 35, the adjustment of the solid carbonaceous fuel supply amount by the belt moving speed is reflected in the amount of pulverized fuel supplied to the combustion burner with a certain delay time.

[0017] Each of the combustion burners 100A, 100B, 100C, 100D, and 100E is connected to an ammonia fuel supply unit 50 via an ammonia fuel supply pipe 51, 52, 53, 53, and 55. The ammonia fuel supply unit 50 supplies liquid or gas phase ammonia fuel containing ammonia as a component to the ammonia fuel supply pipes 51, 52, 53, 54, and 55. The ammonia fuel is supplied from the ammonia fuel supply pipes 51, 52, 53, 54, and 55 to the combustion burners 100A, 100B, 100C, 100D, and 100E.

[0018] The ammonia fuel supply pipes 51, 52, 53, 54, and 55 are provided with flow rate adjustment units (ammonia fuel adjustment units) 51a, 52a, 53a, 54a, and 55a, respectively. The flow rate adjustment units (ammonia fuel adjustment units) 51a, 52a, 53a, 54a, and 55a are, for example, control valves that adjust the amount of fuel supplied by the opening degree. The flow rate adjustment units 51a, 52a, 53a, 54a, and 55a adjust the amount of ammonia fuel supplied from the ammonia fuel supply pipes 51, 52, 53, 54, and 55 to the combustion burners 100A, 100B, 100C, 100D, and 100E.

[0019] The boiler 10 includes a control unit 60 that controls each part of the boiler 10, including the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a and the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a. The control unit 60 controls the belt movement speed of the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a to control the amount of solid carbonaceous fuel supplied to the pulverizers 31, 32, 33, 34, and 35, thereby indirectly adjusting the supply amount of pulverized fuel supplied from the pulverized fuel supply pipes 26, 27, 28, 29, and 30 to the combustion burners 100A, 100B, 100C, 100D, and 100E. In addition, the control unit 60 adjusts the supply amount of ammonia fuel supplied to the combustion burners 100A, 100B, 100C, 100D, and 100E from the ammonia fuel supply pipes 51, 52, 53, 54, and 55 by controlling the opening degree of the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a. That is, the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a directly control the supply amount of ammonia fuel.

[0020] The furnace 11 is provided with a wind box 36 at the mounting positions of the combustion burners 100A, 100B, 100C, 100D, and 100E, and one end of an air duct 37 is connected to the wind box 36, and a blower 38 is attached to the other end of the air duct 37. Furthermore, the furnace 11 is provided with an additional air nozzle 39 vertically above the mounting positions of the combustion burners 100A, 100B, 100C, 100D, and 100E.

[0021] An end of a branch air duct 40 branched off from the air duct 37 is connected to the additional air nozzle 39. Therefore, the combustion air sent by the blower 38 can be supplied from the air duct 37 to the wind box 36, and then from the wind box 36 to each of the combustion burners 100A, 100B, 100C, 100D, and 100E. In addition, the combustion air sent by the blower 38 can be supplied from the branch air duct 40 to the additional air nozzle 39.

[0022] A flue 13 is connected to the upper vertical portion of the furnace 11, and this flue 13 is provided with superheaters 41, 42, reheaters 43, 44, and economizers 45, 46, 47, which are heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated by combustion in the furnace 11 and water or steam.

[0023] An exhaust gas pipe 48 through which the combustion gas that has undergone heat exchange is discharged as exhaust gas is connected to the downstream side of the gas flow of the flue 13. An air heater 49 is provided between the exhaust gas pipe 48 and the air duct 37, and heat is exchanged between the air flowing through the air duct 37 and the exhaust gas flowing through the exhaust gas pipe 48, thereby raising the temperature of the combustion air to be supplied to the combustion burners 100A, 100B, 100C, 100D, and 100E. A chimney (not shown) is provided at the downstream end of the exhaust gas pipe 48.

[0024] The combustion burners 100A, 100B, 100C, 100D, and 100E blow pulverized fuel and ammonia fuel into the furnace 11, and also blow combustion air into the furnace 11, which is ignited at this time to form a flame. In the furnace 11, the pulverized fuel, ammonia fuel, and combustion air combust to generate a flame. When the flame is generated in a vertically lower region of the furnace 11, the combustion gas (exhaust gas) rises inside the furnace 11 and is discharged into the flue 13.

[0025] Water supplied from a water supply pump (not shown) is preheated by economizers 45, 46, and 47, and then introduced into superheaters 41 and 42 through heat transfer tubes (not shown) that constitute the furnace wall, where superheated steam is generated by heat exchange with the combustion gas.

[0026] The superheated steam generated in the superheaters 41, 42 is supplied to a steam turbine (not shown) of a power plant (power generation facility). The steam turbine is connected to a generator, and generates electricity by driving the generator with the steam generated in the boiler 10. The steam turbine may be a multi-stage turbine including a low-pressure turbine that introduces steam discharged from the high-pressure turbine into reheaters 43, 44 of the boiler 100 and utilizes the resuperheated steam.

[0027] Next, the combustion device 12 will be described in detail. However, since the combustion burners 100A, 100B, 100C, 100D, and 100E constituting this combustion device 12 have almost the same configuration, only the combustion burner 100A located at the top will be described.

[0028] FIG. 2 is a front view showing the combustion burner 100A shown in FIG. 1. As shown in FIG. 2, the combustion burner 100A has an ammonia fuel burner 110, a pair of pulverized fuel burners (solid fuel burners) 120, and a pair of air nozzles 130. The ammonia fuel burner 110, the pulverized fuel burner 120, and the air nozzle 130 are arranged along the vertical direction VD at the same position in the horizontal direction HD. The ammonia fuel burner 110 is a device that injects ammonia fuel into the furnace 11 and burns it. The pulverized fuel burner 120 is a device that injects pulverized fuel into the furnace 11 and burns it. The air nozzle 130 is a device that supplies combustion air to the furnace 11. Note that the configuration of the combustion burner 100A is not limited to this. For example, the number of the ammonia fuel burner 110, the pulverized fuel burner 120, and the air nozzle 130 may be one or three or more. Furthermore, the order of the ammonia fuel burner 110, the pulverized fuel burner 120, and the air nozzle 130 may be set arbitrarily.

[0029] Fig. 3 is a cross-sectional view showing the ammonia-fueled burner 110 of the combustion burner 100A of the boiler 10 shown in Fig. 1. As shown in Fig. 3, the combustion burner 100A has ammonia-fueled burners 110a, 110b, 110c, and 110d attached to four wall surfaces 11a, 11b, 11c, and 11d that form the furnace 11. The wall surfaces 11a, 11b, 11c, and 11d are each installed along the vertical direction.

[0030] Branch pipes 51A, 51B, 51C, and 51D branched from an ammonia fuel supply pipe 51 are connected to the ammonia fuel burners 110a, 110b, 110c, and 110d, respectively. In addition, branch pipes 37a, 37b, 37c, and 37d branched from an air duct 37 are connected to the ammonia fuel burners 110a, 110b, 110c, and 110d, respectively.

[0031] The ammonia fuel burner 110a is installed on the wall surface (first wall surface) 11a, and is installed at a position close to the wall surface 11b among the wall surfaces (second wall surface) 11b and (third wall surface) 11d arranged to face the wall surface 11a at a position adjacent to the wall surface 11a. The ammonia fuel burner 110b is installed on the wall surface 11b, and is installed at a position close to the wall surface 11c among the wall surfaces 11a and 11c arranged to face the wall surface 11b at a position adjacent to the wall surface 11b.

[0032] The ammonia fuel burner 110c is installed on the wall surface 11c and is installed at a position close to the wall surface 11d among the wall surfaces 11d and 11b arranged to face the wall surface 11c at a position adjacent to the wall surface 11c. The ammonia fuel burner 110d is installed on the wall surface 11d and is installed at a position close to the wall surface 11a among the wall surfaces 11a and 11c arranged to face the wall surface 11d at a position adjacent to the wall surface 11d.

[0033] Therefore, each ammonia fuel burner 110a, 110b, 110c, 110d on each wall surface of the furnace 11 can inject ammonia fuel into the furnace 11 at a slight angle with respect to the center Ct of the furnace 11, forming four flames F1, F2, F3, F4. The flames F1, F2, F3, F4 become swirling flame flows that swirl counterclockwise when viewed from above the furnace 11. Here, the flames swirl counterclockwise, but the ammonia fuel burners 110a, 110b, 110c, 110d may be arranged to become swirling flame flows that swirl clockwise.

[0034] Fig. 4 is a cross-sectional view showing the pulverized fuel burner 120 of the combustion burner 100A of the boiler 10 shown in Fig. 1. The combustion burner 100A has pulverized fuel burners 120a, 120b, 120c, and 120d attached to four wall surfaces 11a, 11b, 11c, and 11d that form the furnace 11, as shown in Fig. 4.

[0035] The pulverized fuel burners 120a, 120b, 120c, and 120d are respectively connected to branch pipes 26a, 26b, 26c, and 26d branched from the pulverized fuel supply pipe 26. In addition, the pulverized fuel burners 120a, 120b, 120c, and 120d are respectively connected to branch pipes 37a, 37b, 37c, and 37d branched from the air duct 37.

[0036] The pulverized fuel burner 120a is installed on the wall surface (first wall surface) 11a, and is installed at a position close to the wall surface 11b among the wall surface (second wall surface) 11b and the wall surface (third wall surface) 11d arranged opposite to the wall surface 11a at a position adjacent to the wall surface 11a. The pulverized fuel burner 120b is installed on the wall surface 11b, and is installed at a position close to the wall surface 11c among the wall surface 11a and the wall surface 11c arranged opposite to the wall surface 11b at a position adjacent to the wall surface 11b.

[0037] The pulverized fuel burner 120c is installed on the wall surface 11c and is installed at a position close to the wall surface 11d among the wall surfaces 11d and 11b arranged opposite the wall surface 11c at a position adjacent to the wall surface 11c. The pulverized fuel burner 120d is installed on the wall surface 11d and is installed at a position close to the wall surface 11a among the wall surfaces 11a and 11c arranged opposite the wall surface 11d at a position adjacent to the wall surface 11d.

[0038] Therefore, each of the pulverized fuel burners 120a, 120b, 120c, and 120d on each wall surface of the furnace 11 can inject pulverized fuel into the furnace 11 at a slight angle with respect to the center of the furnace 11, forming four flames F1, F2, F3, and F4. The flames F1, F2, F3, and F4 become swirling flame flows that swirl counterclockwise when viewed from above the furnace 11. Here, the flames swirl counterclockwise, but the pulverized fuel burners 120a, 120b, 120c, and 120d may be arranged to become swirling flame flows that swirl clockwise.

[0039] As shown in Figures 3 and 4, the ammonia fuel burner 110a and the pulverized fuel burner 120a are arranged at the same position on the wall surface 11a when the furnace 11 is viewed in a plan view along the vertical direction VD. The ammonia fuel burner 110b and the pulverized fuel burner 120b are arranged at the same position on the wall surface 11b when the furnace 11 is viewed in a plan view along the vertical direction VD. The ammonia fuel burner 110c and the pulverized fuel burner 120c are arranged at the same position on the wall surface 11c when the furnace 11 is viewed in a plan view along the vertical direction VD. The ammonia fuel burner 110d and the pulverized fuel burner 120d are arranged at the same position on the wall surface 11d when the furnace 11 is viewed in a plan view along the vertical direction VD.

[0040] Next, a method for controlling the boiler 10 of this embodiment will be described with reference to Fig. 5 to Fig. 8. Fig. 5 is a flowchart showing a method for controlling the boiler 10 according to the first embodiment of the present disclosure. Fig. 6 is a graph showing the time change in the load of the boiler 10. Fig. 7 is a graph showing the time change in the supply amount of pulverized fuel. Fig. 8 is a graph showing the time change in the supply amount of ammonia fuel. Figs. 7 and 8 show the supply amount of pulverized fuel and the supply amount of ammonia fuel when the mixed combustion ratio of ammonia fuel is 20%.

[0041] 5 is executed by the control unit 60. The control unit 60 in this embodiment controls the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a and the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a so that the load of the boiler 10 corresponds to a command value.

[0042] 5 is a process that is started in response to the control unit 60 increasing the load of the boiler 10 from the current load L1 toward a target value L2. Here, the load of the boiler 10 refers to, for example, the ratio of the actual amount of evaporation of main steam to the amount of evaporation of main steam generated when the boiler 10 is operated at rated speed. Also, as an index of the boiler load, other indexes such as the temperature of main steam, the pressure of main steam, and the generator output may be used instead of the amount of evaporation of main steam.

[0043] As shown in Fig. 6, the load of the boiler 10 is constant at L1 from time t0 to time t1. The load of the boiler 10 is increased at a specified rate of change from a target value L2 given at time t1 to time t4. The process of the flowchart in Fig. 5 starts at time t1 and ends at time t4. The comparative example shown in Fig. 6 shows the actual measured value of the boiler load when only the pulverized fuel is increased when the load of the boiler 10 is increased from L1 to L2.

[0044] In step S101, the control unit 60 determines whether the mixed-combustion ratio of ammonia fuel is 20% or more, and if YES, the process proceeds to step S102, and if NO, the process proceeds to step S103. Here, the mixed-combustion ratio of ammonia fuel refers to the ratio of the heat input amount of ammonia fuel to the total heat input amount, which is the sum of the heat input amount of the solid fuel supplied to the boiler 10 and the heat input amount of the ammonia fuel.

[0045] The control unit 60 presets the mixed combustion ratio of ammonia fuel, and controls the flow rate adjustment units 31a, 32a, 33a, 34a, 35a and the flow rate adjustment units 51a, 52a, 53a, 54a, 55a so that the mixed combustion ratio of ammonia fuel is a preset value. For example, the control unit 60 controls the flow rate adjustment units 31a, 32a, 33a, 34a, 35a and the flow rate adjustment units 51a, 52a, 53a, 54a, 55a so that the mixed combustion ratio of ammonia fuel is 20% or more and 80% or less. The control unit 60 may control the flow rate adjustment units 31a, 32a, 33a, 34a, 35a and the flow rate adjustment units 51a, 52a, 53a, 54a, 55a so that the mixed combustion ratio of ammonia fuel is 20% or more and 50% or less.

[0046] In step S102, the control unit 60 controls the openings of the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a so as to increase the supply amount of ammonia fuel at a specified rate of change. As shown in Fig. 8, the control unit 60 gradually increases the supply amount of ammonia fuel from Qa1 at time t1 at a specified rate of change from time t1 to time t2.

[0047] The control unit 60 executes step S102 when the mixed-combustion ratio of ammonia fuel is 20% or more. This is because, when the mixed-combustion ratio of ammonia fuel is less than 20%, if ammonia fuel is used to increase the load of the boiler 10, the mixed-combustion ratio of ammonia fuel may largely deviate from a preset value.

[0048] In step S103, the control unit 60 controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a to increase the supply amount of pulverized fuel at a specified rate of change. The control unit 60 executes step S103 when the ammonia fuel co-combustion ratio is 20% or more and when it is less than 20%. As shown in Fig. 7, the control unit 60 gradually increases the supply amount of pulverized fuel from Qc1 at time t1 to Qc2 at time t4 at a specified rate of change from time t1 to time t4.

[0049] In step S104, the control unit 60 determines whether the absolute value of the difference between the command value Lt and the actual measured value La of the load of the boiler 10 at the current time is equal to or greater than a predetermined value, and if YES, the process proceeds to step S105, and if NO, the process proceeds to step S106. When the evaporation rate of the main steam is used as the load index indicating the load of the boiler 10, the actual measured value of the load of the boiler 10 is measured by a measurement unit (not shown) that measures the flow rate of the main steam.

[0050] In step S105, since the absolute value of the difference between the command value Lt and the actual measured value La of the load of the boiler 10 deviates by a predetermined value Lpr or more, the control unit 60 changes the rate of change of the supply amount of ammonia fuel so that the actual measured value La approaches the command value Lt. The control unit 60 changes the rate of change of the supply amount of ammonia fuel by controlling the opening degrees of the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a.

[0051] The control unit 60 reduces the rate of change of the supply amount of ammonia fuel when the actual measurement value La is higher than the command value Lt by a predetermined value Lpr or more. Also, the control unit 60 increases the rate of change of the supply amount of ammonia fuel when the actual measurement value La is lower than the command value Lt by a predetermined value Lpr or more. Fig. 6 shows an example in which the actual measurement value La becomes lower than the command value Lt by the predetermined value Lpr or more at time t2, and becomes higher than the command value Lt by the predetermined value Lpr or more at time t3.

[0052] As shown in Fig. 8, the control unit 60 increases the rate of change of the supply amount of ammonia fuel from time t2 when the actual measurement value La becomes lower than the command value Lt by a predetermined value Lpr or more to time t3 when the actual measurement value La becomes higher than the command value Lt by a predetermined value Lpr or more. Also, the control unit 60 decreases the rate of change of the supply amount of ammonia fuel from time t3 to time t4. The comparative example shown in Fig. 8 is an example in which the specified rate of change of the supply amount of ammonia fuel from time t1 to time t2 is maintained from time t2 to time t4.

[0053] In step S106, the control unit 60 determines whether the command value for the load of the boiler 10 has reached the target value L2, and if YES, the process proceeds to step S107, and if NO, the process returns to step S104.

[0054] In step S107, in response to the command value of the load of the boiler 10 reaching the target value L2, the control unit 60 controls the opening degree of the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a so that the supply amount of ammonia fuel supplied to the ammonia fuel burner 110 is maintained at a supply amount Qa2 that results in a specified mixed-combustion ratio.

[0055] In step S108, the control unit 60 controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a so that the amount of pulverized fuel supplied to the pulverized fuel burner 120 becomes a specified mixed combustion ratio in response to the command value of the load of the boiler 10 reaching the target value L2. After executing step S108, the control unit 60 ends the process of this flowchart.

[0056] 5, when executing a load increasing operation (load changing operation) for increasing the load of the boiler 10 from L1 to L2, the control unit 60 controls the apertures of the flow rate adjusting units 51a, 52a, 53a, 54a, and 55a so as to gradually increase the supply amount of ammonia fuel supplied to the ammonia fuel burner 110 during an operation period from time t1 when the load increasing operation starts to time t4 when the load increasing operation stops. The load increasing operation is an operation executed in an operating state after the start of the boiler 10.

[0057] In the flowchart shown in Figure 5, when performing a load increasing operation to increase the load of the boiler 10 from L1 to L2, the control unit 60 controls the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a so as to gradually increase the amount of pulverized fuel supplied to the pulverized fuel burner 120 during the operation period from time t1 when the load increasing operation starts to time t4 when the load increasing operation stops.

[0058] In the above, an example has been described in which the control unit 60 executes a load increasing operation (load changing operation) for increasing the load of the boiler 10 from L1 to L2, but the control unit 60 can also execute a load decreasing operation (load changing operation) for decreasing the load of the boiler 10 from L2 to L1. When the control unit 60 executes a load decreasing operation, the process of "increasing the supply amount of ammonia fuel at a specified rate of change" in step S102 becomes a process of "decreasing the supply amount of ammonia fuel at a specified rate of change". In addition, the process of "increasing the supply amount of pulverized fuel at a specified rate of change" in step S103 becomes a process of "decreasing the supply amount of pulverized fuel at a specified rate of change".

[0059] The boiler 10 of the present embodiment described above provides the following actions and effects. According to the boiler 10 of this embodiment, when a load increasing operation is performed to increase the load of the boiler 10, the supply amount of ammonia fuel supplied to the ammonia-fuel burner 110 increases during an operation period from time t1 to time t4 from the start to the completion of the load increasing operation. Comparing ammonia fuel with solid fuel, ammonia fuel (particularly liquid ammonia) has a characteristic that the supply amount is easier to change. Therefore, by increasing the supply amount of ammonia fuel supplied to the ammonia-fuel burner 110, it is possible to improve the followability of the boiler 10 to changes in the load, compared to the case where only the supply amount of solid fuel is increased.

[0060] Furthermore, according to the boiler 10 of this embodiment, when a load increasing operation is performed to increase the load of the boiler 10, the supply amount of pulverized fuel supplied to the pulverized fuel burner 120 increases during the operation period from the start to the completion of the load increasing operation. Since the supply amounts of both ammonia fuel and pulverized fuel are increased, the boiler 10 can improve its ability to follow changes in the load while maintaining a relatively constant mixed combustion ratio, compared to the case where only the supply amount of pulverized fuel is increased.

[0061] According to the boiler 10 of this embodiment, by setting the ammonia fuel co-combustion ratio to 20% or more and 80% or less, the amount of carbon dioxide generated can be suppressed compared to when the ammonia fuel co-combustion ratio is less than 20%. In addition, since the ammonia fuel co-combustion ratio is relatively high, even if ammonia fuel is used when performing a load increasing operation to increase the load of the boiler 10, the ammonia fuel co-combustion ratio can be maintained in an appropriate range of 20% or more and 80% or less.

[0062] Second Embodiment Hereinafter, a boiler 10 according to a first embodiment of the present disclosure will be described with reference to the drawings. The second embodiment is a modified example of the first embodiment, and is the same as the first embodiment except as otherwise specifically described below, and therefore the description thereof will be omitted below.

[0063] The control unit 60 in the first embodiment controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a so as to increase the supply amount of pulverized fuel supplied to the pulverized fuel burner 120 when the load of the boiler 10 is increased. In contrast, the control unit 60 in the present embodiment controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a so as to keep the supply amount of pulverized fuel supplied to the pulverized fuel burner 120 constant when the load of the boiler 10 is increased.

[0064] A method for controlling the boiler 10 of this embodiment will be described with reference to Fig. 9 to Fig. 11. Fig. 9 is a flowchart showing a method for controlling the boiler 10 according to the second embodiment of the present disclosure. Fig. 10 is a graph showing the time change in the supply amount of pulverized fuel. Fig. 11 is a graph showing the time change in the supply amount of ammonia fuel. Figs. 10 and 11 show the supply amount of pulverized fuel and the supply amount of ammonia fuel when the mixed combustion ratio of ammonia fuel is 20%. In addition, the time change in the load of the boiler 10 is assumed to be the same as the graph shown in Fig. 6.

[0065] In FIG. 9, steps S201, S202, S203, S204, S205, S208, and S209 are similar to steps S101, S102, S104, S105, S106, S107, and S108 in FIG. 6 of the first embodiment, and therefore will not be described below.

[0066] In the boiler 10 of the first embodiment, the control unit 60 increases the supply amount of pulverized fuel at a specified rate of change in step S103. On the other hand, in the boiler 10 of the present embodiment, the control unit 60 does not increase the supply amount of pulverized fuel at a specified rate of change. In the boiler 10 of the present embodiment, the control unit 60 controls the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a so that the supply amount of pulverized fuel is constant when the load of the boiler 10 is increased.

[0067] In step S206, the control unit 60 controls the apertures of the flow rate adjusting units 51a, 52a, 53a, 54a, and 55a so that the supply amount of ammonia fuel supplied to the ammonia fuel burner 110 decreases at a specified rate of change in response to the lapse of a certain time since the command value of the load of the boiler 10 reached the target value L2. Fig. 11 is a graph showing the time change of the supply amount of ammonia fuel.

[0068] 11, the control unit 60 controls the apertures of the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a so that the supply amount of ammonia fuel decreases at a prescribed rate of change during the period from time t5 to time t6, which is a certain time period after time t4 when the command value of the load of the boiler 10 reaches the target value L2. The reason for decreasing the supply amount of ammonia fuel is to reduce the supply amount of ammonia fuel used to increase the load of the boiler 10 from L1 to L2, and to achieve a set mixed combustion ratio.

[0069] In step S207, the control unit 60 controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a so that the supply rate of the pulverized fuel supplied to the pulverized fuel burner 120 increases at a specified rate of change when a certain time has elapsed since the command value of the load of the boiler 10 reached the target value L2. Fig. 10 is a graph showing the time change of the supply rate of the pulverized fuel.

[0070] As shown in Fig. 10, the control unit 60 controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a so that the supply amount of pulverized fuel increases at a specified rate of change during the period from time t5 to time t6, which is a certain time period after time t4 when the command value of the load of the boiler 10 reaches the target value L2. The reason why the supply amount of pulverized fuel is increased is to offset the gradual decrease in the supply amount of ammonia fuel during the period from time t5 to time t6, and to maintain the load of the boiler 10 constant.

[0071] If the ammonia fuel co-combustion ratio is less than 20% in step S201, the process proceeds to step S210, where the control unit 60 controls the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a to increase the supply amount of pulverized fuel at a specified rate of change.

[0072] In step S211, the control unit 60 determines whether the absolute value of the difference between the command value Lt and the actual measured value La of the load of the boiler 10 at the current time is equal to or greater than a predetermined value Lpr, and if YES, the process proceeds to step S212, and if NO, the process proceeds to step S213. When the evaporation rate of the main steam is used as the load index of the boiler 10, the actual measured value of the load of the boiler 10 is measured by a measurement unit (not shown) that measures the flow rate of the main steam.

[0073] In step S212, since the command value Lt of the load of the boiler 10 and the actual measured value La deviate from each other by a predetermined value Lpr or more, the control unit 60 changes the rate of change of the supply amount of the pulverized fuel so that the actual measured value La approaches the command value Lt. The control unit 60 changes the rate of change of the supply amount of the pulverized fuel by controlling the flow rate adjustment units 31a, 32a, 33a, 34a, and 35a.

[0074] In step S213, the control unit 60 determines whether the command value for the load of the boiler 10 has reached the target value L2, and if YES, the process proceeds to step S214, and if NO, the process returns to step S211.

[0075] In step S214, the control unit 60 controls the opening degree of the flow rate adjustment units 51a, 52a, 53a, 54a, and 55a so that the supply amount of ammonia fuel supplied to the ammonia fuel burner 110 increases at a specified rate of change in response to the lapse of a certain time since the load command value of the boiler 10 reaches the target value L2.

[0076] In step S215, the control unit 60 controls the flow rate adjusting units 31a, 32a, 33a, 34a, and 35a so that the supply amount of pulverized fuel supplied to the pulverized fuel burner 120 decreases at a specified rate of change in response to the lapse of a certain time after the command value of the load of the boiler 10 reaches the target value L2. The reason why the supply amount of pulverized fuel is decreased while the supply amount of ammonia fuel is increased is to reduce the supply amount of pulverized fuel used to increase the load of the boiler 10 from L1 to L2 and achieve a set mixed combustion ratio.

[0077] According to the boiler 10 of this embodiment, when performing a load increasing operation to increase the load of the boiler 10, the supply amount Qc1 of the pulverized fuel is constant during the operation period from time t1 to time t4 from the start to the completion of the load increasing operation, so that the load of the boiler 10 is increased only by the ammonia fuel. Therefore, compared to the case where the supply amount of the pulverized fuel is increased, the fluctuation of the heat input amount to the boiler 10 can be suppressed, and the followability of the boiler 10 to the change in the load can be improved.

[0078] In the above, an example has been described in which the control unit 60 executes a load increasing operation (load changing operation) for increasing the load of the boiler 10 from L1 to L2, but the control unit 60 can also execute a load decreasing operation (load changing operation) for decreasing the load of the boiler 10 from L2 to L1. When the control unit 60 executes a load decreasing operation, the process of "increasing the supply amount of ammonia fuel at a specified rate of change" in steps S202 and S214 becomes a process of "decreasing the supply amount of ammonia fuel at a specified rate of change". In addition, the process of "increasing the supply amount of pulverized fuel at a specified rate of change" in steps S210 and S207 becomes a process of "decreasing the supply amount of pulverized fuel at a specified rate of change".

[0079] Moreover, the process of "decreasing the supply amount of ammonia fuel at a specified rate of change" in step S206 becomes a process of "increasing the supply amount of ammonia fuel at a specified rate of change". Moreover, the process of "decreasing the supply amount of pulverized fuel at a specified rate of change" in step S215 becomes a process of "increasing the supply amount of pulverized fuel at a specified rate of change".

[0080] The boiler, the power generation facility, and the boiler control method described in the above-described embodiments can be understood, for example, as follows. A boiler according to a first aspect of the present disclosure includes a solid fuel burner (120) that injects solid fuel into a furnace (11) and burns it, a solid fuel adjustment unit (31a-35a) that adjusts the supply amount of the solid fuel supplied to the solid fuel burner, an ammonia fuel burner (110) that injects ammonia fuel into the furnace (11) and burns it, an ammonia fuel adjustment unit (51a-55a) that adjusts the supply amount of the ammonia fuel supplied to the ammonia fuel burner, and a control unit that controls the solid fuel adjustment unit and the ammonia fuel adjustment unit, and when performing a load changing operation to change the load of the boiler, the control unit controls the ammonia fuel adjustment unit to change the supply amount of the ammonia fuel supplied to the ammonia fuel burner during an operation period from the start of the load changing operation to the completion of the load changing operation.

[0081] According to the boiler according to the first aspect of the present disclosure, when a load change operation is performed to change the load of the boiler, the supply amount of ammonia fuel supplied to the ammonia-fueled burner increases during the operation period from the start to the completion of the load change operation. Comparing ammonia fuel with solid fuel, ammonia fuel (particularly liquid ammonia) has a characteristic that it is easier to increase the heat input. Therefore, by changing the supply amount of ammonia fuel supplied to the ammonia-fueled burner, the load change speed of the boiler can be increased compared to the case where only the supply amount of solid fuel is changed.

[0082] The boiler according to the second aspect of the present disclosure is the first aspect, further comprising the following configuration: That is, the control unit controls the solid fuel adjusting unit to change the supply amount of the solid fuel supplied to the solid fuel burner when changing the load of the boiler. According to the boiler according to the second aspect of the present disclosure, when a load change operation is performed to change the load of the boiler, the supply amount of solid fuel supplied to the solid fuel burner increases during the operation period from the start to the completion of the load change operation. Since the supply amounts of both ammonia fuel and solid fuel are changed, the load change speed of the boiler can be increased compared to the case where only the supply amount of solid fuel is changed.

[0083] The boiler according to a third aspect of the present disclosure is the first aspect, further comprising the following configuration: That is, the control unit controls the solid fuel adjusting unit so that the amount of the solid fuel supplied to the solid fuel burner is constant when the load of the boiler is changed. According to the boiler according to the third aspect of the present disclosure, when a load change operation is performed to change the load of the boiler, the supply amount of solid fuel is constant during the operation period from the start to the completion of the load change operation, so that the load of the boiler is changed only by the ammonia fuel. Therefore, the load change speed of the boiler can be increased compared to the case where the supply amount of solid fuel is changed.

[0084] The boiler according to a fourth aspect of the present disclosure is any one of the first to third aspects, further comprising the following configuration: That is, the control unit controls the solid fuel preparation unit and the ammonia fuel preparation unit so that a ratio of the heat input amount of the ammonia fuel to a total heat input amount, which is the sum of the heat input amount of the solid fuel and the heat input amount of the ammonia fuel, during a predetermined operating period in which the boiler is in an operating state is 20% or more and 80% or less. According to the boiler according to the fourth aspect of the present disclosure, by setting the ammonia fuel co-combustion ratio at 20% or more and 80% or less, the amount of carbon dioxide generated can be suppressed compared to when the ammonia fuel co-combustion ratio is less than 20%. Furthermore, since the ammonia fuel co-combustion ratio is relatively high, the ammonia fuel co-combustion ratio can be maintained in an appropriate range of 20% or more and 80% or less, even if ammonia fuel is used when performing a load increase operation to increase the load of the boiler.

[0085] The boiler according to the fifth aspect of the present disclosure is the third aspect, and further includes the following configuration: That is, the control unit controls the solid fuel preparation unit and the ammonia fuel preparation unit so that the ratio of the heat input amount of the ammonia fuel to the total heat input amount, which is the sum of the heat input amount of the solid fuel and the heat input amount of the ammonia fuel, is 20% or more and 50% or less during a predetermined operating period in which the boiler is in an operating state. According to the boiler according to the fifth aspect of the present disclosure, by setting the ammonia fuel co-combustion ratio to 20% or more and 50% or less, the amount of carbon dioxide generated can be suppressed compared to when the ammonia fuel co-combustion ratio is less than 20%. Furthermore, since the ammonia fuel co-combustion ratio is relatively high, the ammonia fuel co-combustion ratio can be maintained in an appropriate range of 20% or more and 50% or less, even if ammonia fuel is used when performing a load increasing operation to increase the load of the boiler.

[0086] The boiler according to a sixth aspect of the present disclosure is the boiler of any one of the first to third aspects, further including the following configuration: That is, the load changing operation is an operation executed in an operating state after startup of the boiler. According to the boiler according to the sixth aspect of the present disclosure, the load change rate of the boiler can be increased in an operating state after the boiler is started.

[0087] A power generation facility according to a seventh aspect of the present disclosure includes a boiler according to any one of the first to third aspects, a steam turbine driven by steam generated in the boiler, and a generator connected to the steam turbine. According to the power generation facility according to the seventh aspect of the present disclosure, by changing the supply amount of ammonia fuel supplied to the ammonia fuel burner, the boiler load change rate can be increased compared to the case where only the supply amount of solid fuel is changed.

[0088] In a boiler control method according to an eighth aspect of the present disclosure, the boiler has a solid fuel burner that forms a flame in a furnace using solid fuel, a solid fuel adjustment unit that adjusts the supply amount of the solid fuel supplied to the solid fuel burner, an ammonia fuel burner that forms a flame in the furnace using ammonia fuel, and an ammonia fuel adjustment unit that adjusts the supply amount of the ammonia fuel supplied to the ammonia fuel burner, and includes a control step of controlling the solid fuel adjustment unit and the ammonia fuel adjustment unit, and the control step controls the ammonia fuel adjustment unit to change the supply amount of the ammonia fuel supplied to the ammonia fuel burner during an operation period from the start of the load change operation to the completion of the load change operation when a load change operation that changes the load of the boiler is performed.

[0089] According to the boiler control method according to the eighth aspect of the present disclosure, when a load change operation for changing the load of the boiler is performed, the supply amount of ammonia fuel supplied to the ammonia-fueled burner is changed during the operation period from the start to the completion of the load change operation. Comparing ammonia fuel with solid fuel, ammonia fuel (particularly liquid ammonia) has a characteristic that the heat input is easier to change. Therefore, by changing the supply amount of ammonia fuel supplied to the ammonia-fueled burner, the load change speed of the boiler can be increased compared to the case where only the supply amount of solid fuel is changed. [Explanation of symbols]

[0090] 10. Boiler 11 Furnace 12 Combustion equipment 13 Flue 26 Fine fuel supply pipe 31, 32, 33, 34, 35 Crusher 31a, 32a, 33a, 34a, 35a Flow rate adjustment section (solid fuel adjustment section) 50 Ammonia fuel supply unit 51, 52, 53, 54, 55 Ammonia fuel supply pipe 51a, 52a, 53a, 54a, 55a Flow rate adjustment unit (ammonia fuel adjustment unit) 60 Control section 100A, 100B, 100C, 100D, 100E Combustion burner 110 Ammonia fuel burner 120 Pulverized fuel burner 130 Air Nozzle Lt command value L2 target value La actual value Lpr predetermined value VD Vertical direction

Claims

1. a solid fuel burner that injects solid fuel into the furnace and burns it; a solid fuel adjusting unit that adjusts the amount of the solid fuel supplied to the solid fuel burner; an ammonia fuel burner that injects ammonia fuel into the furnace and burns it; an ammonia fuel adjusting unit that adjusts the amount of the ammonia fuel supplied to the ammonia fuel burner; a control unit that controls the solid fuel preparation unit and the ammonia fuel preparation unit, the control unit controls the ammonia fuel adjusting unit to change the supply amount of the ammonia fuel supplied to the ammonia-fuel burner during an operation period from start to completion of a load changing operation when executing a load changing operation to change the load of the boiler.

2. The boiler according to claim 1 , wherein the control unit controls the solid fuel adjusting unit to change the amount of the solid fuel supplied to the solid fuel burner when changing the load of the boiler.

3. 2. The boiler according to claim 1, wherein the control unit controls the solid fuel adjusting unit so that the amount of the solid fuel supplied to the solid fuel burner is constant when the load of the boiler is changed.

4. 4. The boiler according to claim 1, wherein the control unit controls the solid fuel preparation unit and the ammonia fuel preparation unit so that a ratio of the heat input amount of the ammonia fuel to a total heat input amount, which is the sum of the heat input amounts of the solid fuel and the ammonia fuel, is 20% or more and 80% or less during a predetermined operating period in which the boiler is in an operating state.

5. 4. The boiler according to claim 3, wherein the control unit controls the solid fuel adjustment unit and the ammonia fuel adjustment unit so that a ratio of the heat input amount of the ammonia fuel to a total heat input amount, which is the sum of the heat input amount of the solid fuel and the heat input amount of the ammonia fuel, is 20% or more and 50% or less during a predetermined operating period in which the boiler is in an operating state.

6. The boiler according to any one of claims 1 to 3, wherein the load changing operation is an operation that is executed in an operating state after startup of the boiler.

7. A measuring unit is provided to measure the actual load value of the boiler, 4. The boiler according to claim 1, wherein the control unit controls the ammonia fuel adjusting unit to decrease a rate of change of the supply amount of the ammonia fuel when the actual measurement value is higher than a command value of the load of the boiler by a predetermined value or more, and to increase a rate of change of the supply amount of the ammonia fuel when the actual measurement value is lower than the command value by the predetermined value or more.

8. The boiler according to any one of claims 1 to 3; a steam turbine driven by steam generated in the boiler; a generator coupled to the steam turbine.

9. A method for controlling a boiler, comprising: The boiler comprises: a solid fuel burner that forms a flame using solid fuel in the furnace; a solid fuel adjusting unit that adjusts the amount of the solid fuel supplied to the solid fuel burner; an ammonia fuel burner that forms a flame using ammonia fuel in the furnace; an ammonia fuel adjusting unit that adjusts the amount of the ammonia fuel supplied to the ammonia fuel burner, a control step of controlling the solid fuel preparation unit and the ammonia fuel preparation unit, The control method for a boiler includes controlling the ammonia fuel adjusting unit to change the supply amount of the ammonia fuel supplied to the ammonia-fuel burner during an operation period from start to completion of a load changing operation that changes the load of the boiler, when the control step is performed.

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