Combustion furnace, boiler, power generation equipment, and control method for combustion furnace

Abstract

Provided is a combustion furnace (11) that comprises a control unit that controls a solid fuel adjustment unit and an ammonia fuel adjustment unit such that the fuel injected furthest upstream in a flow direction (FD) is a pulverized fuel during mixed combustion operation in which combustion gas generated by combustion of the pulverized fuel and an ammonia fuel is made to flow through the combustion furnace (11) in the flow direction (FD) to be discharged to the outside, the pulverized fuel is injected from at least one of a plurality of combustion burners (100B, 100D, 100F), and the ammonia fuel is injected from at least one of a plurality of combustion burners (100A, 100C, 100E).

Description

Combustion furnace, boiler, power generation equipment, and control method for combustion furnace

[0001] The present disclosure relates to a combustion furnace, a boiler, power generation equipment, and a control method for a combustion furnace.

[0002] Conventionally, a boiler that co-fires pulverized coal and ammonia is known (see, for example, Patent Document 1). The boiler disclosed in Patent Document 1 arranges a plurality of burners at intervals from the upstream side to the downstream side in the flow direction of the combustion gas, and supplies ammonia to other burners except the burner on the most downstream side. According to the boiler disclosed in Patent Document 1, since ammonia is supplied to the burners on the upstream side of the flow direction of the combustion gas, compared with the case where ammonia is supplied to the burner on the most downstream side of the flow direction of the combustion gas, sufficient time can be ensured to decompose NOx generated by the combustion of ammonia into nitrogen.

[0003] Japanese Patent Application Laid-Open No. 2020-112280

[0004] In the boiler disclosed in Patent Document 1, ammonia is supplied to the burner on the most upstream side in the flow direction of the combustion gas. However, the position in the flow direction where the burner on the most upstream side is arranged has a lower ambient temperature than the positions in the flow direction where other burners are arranged. Therefore, in the lower part of the combustion furnace where the ambient gas temperature is low, a part of ammonia may flow through the combustion furnace without burning and be discharged out of the system as unburned ammonia.

[0005] [[ID=|15]] Also, in the lower part of the combustion furnace where the ambient gas temperature is low, nitrous oxide (N ２ O) generated in the process of ammonia combustion may flow through the combustion furnace without being decomposed and be discharged out of the system. Since the global warming potential of nitrous oxide is extremely large compared to that of carbon dioxide (CO ２ ), it is required to suppress its emission amount.

[0006] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a combustion furnace, a boiler, power generation equipment, and a control method for a combustion furnace that can appropriately suppress the discharge of unburned ammonia and nitrous oxide out of the system.

[0007] To solve the above problems, a combustion furnace, boiler, power generation equipment, and a control method for a combustion furnace according to one aspect of this disclosure employ the following means.

[0008] A combustion furnace according to one aspect of the present disclosure is capable of co-firing an ammonia fuel containing ammonia and a first fuel different from the ammonia fuel, and comprises a plurality of first fuel burners that inject and burn the first fuel into the combustion furnace from a plurality of locations at each of a plurality of first arrangement positions arranged at intervals in a predetermined direction, a plurality of ammonia fuel burners that inject and burn the ammonia fuel into the combustion furnace from a plurality of locations at each of second arrangement positions arranged at intervals in the predetermined direction and different from the first arrangement positions, a first fuel adjustment unit that adjusts the amount of the first fuel supplied to the first fuel burners, and the ammonia fuel supplied to the ammonia fuel burners A boiler comprising an ammonia fuel adjustment unit for adjusting the supply amount of ammonia fuel, and a control unit for controlling the first fuel adjustment unit and the ammonia fuel adjustment unit, wherein the combustion gas generated by the combustion of the first fuel and the ammonia fuel is circulated in a predetermined direction in the combustion furnace and discharged to the outside, wherein the control unit controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that the fuel injected at the upstream end in the predetermined direction becomes the first fuel when performing a co-combustion operation in which the first fuel is injected from at least one of the plurality of first fuel burners and the ammonia fuel is injected from at least one of the plurality of ammonia fuel burners.

[0009] A control method for a combustion furnace according to one aspect of the present disclosure, wherein the combustion furnace is capable of co-firing an ammonia fuel containing ammonia and a first fuel different from the ammonia fuel, and comprises a plurality of first fuel burners that inject and burn the first fuel into the combustion furnace from a plurality of locations at each of a plurality of first arrangement positions arranged at intervals in a predetermined direction, a plurality of ammonia fuel burners that inject and burn the ammonia fuel into the combustion furnace from a plurality of locations at each of second arrangement positions that are spaced apart in the predetermined direction and different from the first arrangement positions, and a first fuel adjustment unit that adjusts the amount of the first fuel supplied to the first fuel burners, The system includes an ammonia fuel adjustment unit that adjusts the amount of ammonia fuel supplied to the ammonia fuel burner, and a control step that controls the first fuel adjustment unit and the ammonia fuel adjustment unit when performing a co-firing operation in which the combustion gas generated by the combustion of the first fuel and the ammonia fuel is circulated in the combustion furnace in a predetermined direction and discharged to the outside, the first fuel is injected from at least one of the plurality of first fuel burners, and the ammonia fuel is injected from at least one of the plurality of ammonia fuel burners, so that the fuel injected at the upstream end in the predetermined direction is the first fuel.

[0010] According to this disclosure, it is possible to provide a combustion furnace, boiler, power generation equipment, and a control method for a combustion furnace that can appropriately suppress the emission of unburned ammonia and nitrous oxide outside the system.

[0011] This is a schematic diagram showing a boiler according to one embodiment of the present disclosure. This is a cross-sectional view of a combustion burner that injects ammonia fuel as shown in Figure 1. This is a cross-sectional view of a combustion burner that injects solid fuel as shown in Figure 1. This is a partially enlarged view of the combustion furnace as shown in Figure 1. This is a flowchart showing a control method for a boiler according to one embodiment of the present disclosure. This is a diagram showing the relationship between the distance from the bottom of the combustion furnace and the temperature.

[0012] A boiler 10 equipped with a combustion furnace (furnace) 11 according to one embodiment of the present disclosure will be described below with reference to the drawings. The boiler 10 according to this embodiment is a device that burns pulverized fuel (solid fuel) and ammonia fuel using a combustion burner and recovers the heat generated by this combustion. The fuel that the combustion furnace 11 of the boiler 10 according to this embodiment burns together with the ammonia fuel may be a fuel other than pulverized fuel, as long as it has higher combustibility than ammonia fuel.

[0013] Figure 1 is a schematic diagram showing a boiler 10 according to one embodiment of the present disclosure. As shown in Figure 1, the boiler 10 of this embodiment has a combustion furnace 11, a combustion device 12, and a flue 13. The combustion furnace 11 has a hollow rectangular shape and is installed along the vertical direction, and the combustion device 12 is provided at the lower part of the furnace wall that constitutes the combustion furnace 11. In the boiler 10 of this embodiment, the combustion gas generated by the combustion of pulverized fuel and ammonia fuel is circulated in the vertical direction VD in the combustion furnace 11 and discharged to the flue 13.

[0014] The combustion device 12 has a plurality of combustion burners 100A, 100B, 100C, 100D, 100E, and 100F mounted on the furnace wall. In this embodiment, the combustion burners 100A, 100B, 100C, 100D, 100E, and 100F are arranged in sets of four at equal intervals along the circumferential direction with the vertical direction VD of the combustion furnace 11 as the central axis, and six sets (six rows) are arranged along the vertical direction. Although six sets are used here, any other number of sets can be used.

[0015] The combustion burners (solid fuel burners) 100B, 100D, and 100F are connected to the crushers 31, 32, and 33 via the fine fuel supply pipes 26, 27, and 28. The crushers 31, 32, and 33 crush solid fuels such as biomass fuel and coal into fine fuel, which is then supplied to the fine fuel supply pipes 26, 27, and 28 along with a transport gas such as air. The fine fuel is then supplied from the fine fuel supply pipes 26, 27, and 28 to the combustion burners 100B, 100D, and 100F.

[0016] The crushers 31, 32, and 33 are connected to solid fuel adjustment units 31a, 32a, and 33a, respectively, via solid fuel supply pipes 31b, 32b, and 33b. The amount of fine fuel supplied to the combustion burners 100B, 100D, and 100F via fine fuel supply pipes 26, 27, and 28 is controlled by adjusting the amount of solid fuel supplied to the crushers 31, 32, and 33 using the solid fuel adjustment units 31a, 32a, and 33a.

[0017] Figure 1 shows an example in which a belt conveyor type fuel supply machine (coal feeder) is applied to the solid fuel adjustment units 31a, 32a, and 33a. For example, the amount of solid fuel supplied to the crushers 31, 32, and 33 is adjusted by the speed at which the belt of the belt conveyor moves. Here, since uncrushed solid carbonaceous fuel remains inside the crushers 31, 32, and 33, the adjustment of the solid fuel supply amount by the belt's speed is reflected in the amount of fine fuel supplied to the combustion burner with a certain delay.

[0018] The combustion burners (ammonia fuel burners) 100A, 100C, and 100E are connected to the ammonia fuel supply unit 50 via ammonia fuel supply pipes 51, 52, and 53. The ammonia fuel supply unit 50 supplies liquid or gaseous ammonia fuel containing ammonia as a component to the ammonia fuel supply pipes 51, 52, and 53. The ammonia fuel is supplied from the ammonia fuel supply pipes 51, 52, and 53 to the combustion burners 100A, 100C, and 100E.

[0019] Ammonia fuel adjustment units 51a, 52a, and 53a are provided in the ammonia fuel supply pipes 51, 52, and 53, respectively. The ammonia fuel adjustment units 51a, 52a, and 53a use, for example, control valves that adjust the amount of fuel supplied by the degree of opening. The ammonia fuel adjustment units 51a, 52a, and 53a adjust the amount of ammonia fuel supplied from the ammonia fuel supply pipes 51, 52, and 53 to the combustion burners 100A, 100C, and 100E.

[0020] The boiler 10 includes a control unit 60 that controls each part of the boiler 10, including the solid fuel adjustment units 31a, 32a, 33a and the ammonia fuel adjustment units 51a, 52a, 53a. The control unit 60 indirectly adjusts the amount of pulverized fuel supplied from the pulverized fuel supply pipes 26, 27, 28 to the combustion burners 100B, 100D, 100F by controlling the belt movement speed of the solid fuel adjustment units 31a, 32a, 33a and thereby controlling the amount of solid fuel supplied to the crushers 31, 32, 33.

[0021] Furthermore, the control unit 60 adjusts the amount of ammonia fuel supplied from the ammonia fuel supply pipes 51, 52, and 53 to the combustion burners 100A, 100C, and 100E by controlling the opening of the ammonia fuel adjustment units 51a, 52a, and 53a. In other words, the ammonia fuel adjustment units 51a, 52a, and 53a directly control the amount of ammonia fuel supplied.

[0022] The combustion furnace 11 has wind boxes 36 at the mounting positions of each combustion burner 100A, 100B, 100C, 100D, 100E, and 100F. One end of an air duct 37 is connected to the wind box 36. A blower 38 is attached to the other end of the air duct 37. Additional air nozzles 39 are provided in the combustion furnace 11 vertically above the mounting positions of each combustion burner 100A, 100B, 100C, 100D, and 100E.

[0023] The additional air nozzle 39 is connected to the end of a branch air duct 40 that branches off from the air duct 37. Combustion air supplied by the blower 38 is supplied from the air duct 37 to the wind box 36, and from the wind box 36 to each of the combustion burners 100A, 100B, 100C, 100D, and 100E. Combustion air supplied by the blower 38 is also supplied from the branch air duct 40 to the additional air nozzle 39.

[0024] A flue 13 is connected to the vertical upper part of the combustion furnace 11. The flue 13 is equipped with superheaters 41, 42, reheaters 43, 44, and economizers 45, 46, 47, which are heat exchangers for recovering heat from the combustion gas. These heat exchangers perform heat exchange between the combustion gas generated by combustion in the combustion furnace 11 and water or steam.

[0025] An exhaust gas pipe 48 is connected to the flue 13 on the downstream side of the gas flow, through which the heat-exchanged combustion gas is discharged as exhaust gas. An air heater 49 is provided between the exhaust gas pipe 48 and the air duct 37, and heat exchange occurs between the air flowing through the air duct 37 and the exhaust gas flowing through the exhaust gas pipe 48, raising the temperature of the combustion air 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.

[0026] Combustion burners 100A, 100B, 100C, 100D, and 100E inject pulverized fuel and ammonia fuel into the combustion furnace 11, along with combustion air, and ignite at this time to form a flame. In the combustion furnace 11, the pulverized fuel and ammonia fuel and combustion air burn to produce a flame. When a flame is produced in the lower vertical region of the combustion furnace 11, the combustion gas (exhaust gas) rises inside the combustion furnace 11 and is discharged into the flue 13.

[0027] Water supplied from the water pump (not shown) is preheated by economizers 45, 46, and 47, then introduced into superheaters 41 and 42 via heat transfer tubes (not shown) that make up the furnace wall, where superheated steam is generated through heat exchange with the combustion gas.

[0028] The superheated steam generated in superheaters 41 and 42 is supplied to a steam turbine (not shown) of the power plant (power generation equipment). The steam turbine is connected to a generator and generates electricity by driving the generator with steam generated in the boiler 10. The steam turbine may be a multi-stage turbine equipped with a low-pressure turbine that utilizes steam discharged from a high-pressure turbine and reheated by introducing the steam into reheaters 43 and 44 of the boiler 10.

[0029] Next, the combustion device 12 will be described in detail. Figure 2 is a cross-sectional view of the combustion burner (ammonia fuel burner) 100A that injects the ammonia fuel shown in Figure 1. The configurations of the combustion burners 100C and 100D are the same as those of the combustion burner 100A, so their explanation will be omitted below.

[0030] As shown in Figure 2, the combustion burner 100A has ammonia fuel burners 110a, 110b, 110c, and 110d attached to the four wall surfaces 11a, 11b, 11c, and 11d that form the combustion furnace 11. The wall surfaces 11a, 11b, 11c, and 11d are each installed along the vertical direction VD.

[0031] The ammonia fuel burners 110a, 110b, 110c, and 110d are connected to branch pipes 51A, 51B, 51C, and 51D, respectively, which are branched from the ammonia fuel supply pipe 51. In addition, the ammonia fuel burners 110a, 110b, 110c, and 110d are connected to branch pipes 37a, 37b, 37c, and 37d, respectively, which are branched from the air duct 37.

[0032] The ammonia fuel burner 110a is installed on wall surface 11a and is located in a position close to wall surface 11b among wall surfaces 11b and 11d which are positioned opposite to wall surface 11a. The ammonia fuel burner 110b is installed on wall surface 11b and is located in a position close to wall surface 11c among wall surfaces 11a and 11c which are positioned opposite to wall surface 11b.

[0033] The ammonia fuel burner 110c is installed on wall surface 11c and is located in a position close to wall surface 11d among wall surfaces 11d and 11b which are positioned opposite to wall surface 11c. The ammonia fuel burner 110d is installed on wall surface 11d and is located in a position close to wall surface 11a among wall surfaces 11a and 11c which are positioned opposite to wall surface 11d.

[0034] Therefore, each ammonia fuel burner 110a, 110b, 110c, and 110d located on each wall of the combustion furnace 11 can inject ammonia fuel into the combustion furnace 11 at a slight angle with respect to the center Ct of the combustion furnace 11, thereby forming four flames F1, F2, F3, and F4. The flames F1, F2, F3, and F4 become swirling flame flows that rotate counterclockwise when viewed from above the combustion furnace 11. Here, we have assumed that the flames rotate counterclockwise, but the ammonia fuel burners 110a, 110b, 110c, and 110d may also be arranged to produce swirling flame flows that rotate clockwise.

[0035] Figure 3 is a cross-sectional view of the combustion burner (solid fuel burner) 100B that injects the solid fuel shown in Figure 1. The configurations of the combustion burners 100D and 100F are the same as those of the combustion burner 100B, so their explanation will be omitted below.

[0036] As shown in Figure 3, the combustion burner 100B has solid fuel burners 120a, 120b, 120c, and 120d that are attached to the four wall surfaces 11a, 11b, 11c, and 11d that form the combustion furnace 11.

[0037] The solid fuel burners 120a, 120b, 120c, and 120d are connected to branch pipes 26a, 26b, 26c, and 26d, respectively, which branch off from the pulverized fuel supply pipe 26. In addition, the solid fuel burners 120a, 120b, 120c, and 120d are connected to branch pipes 37a, 37b, 37c, and 37d, respectively, which branch off from the air duct 37.

[0038] The solid fuel burner 120a is installed on wall surface 11a and is located near wall surface 11b, among wall surfaces 11b and 11d which are positioned opposite to wall surface 11a. The solid fuel burner 120b is installed on wall surface 11b and is located near wall surface 11c, among wall surfaces 11a and 11c which are positioned opposite to wall surface 11b.

[0039] The solid fuel burner 120c is installed on wall surface 11c and is located in a position close to wall surface 11d among wall surfaces 11d and 11b which are positioned opposite to wall surface 11c. The solid fuel burner 120d is installed on wall surface 11d and is located in a position close to wall surface 11a among wall surfaces 11a and 11c which are positioned opposite to wall surface 11d.

[0040] Therefore, each solid fuel burner 120a, 120b, 120c, and 120d located on each wall of the combustion furnace 11 can inject pulverized fuel into the combustion furnace 11 at a slight angle relative to the center of the combustion furnace 11, thereby forming four flames F1, F2, F3, and F4. The flames F1, F2, F3, and F4 become swirling flame flows that rotate counterclockwise when viewed from above the combustion furnace 11. Here, we have assumed that the flames rotate counterclockwise, but the solid fuel burners 120a, 120b, 120c, and 120d may also be arranged to produce swirling flame flows that rotate clockwise.

[0041] As shown in Figures 2 and 3, the ammonia fuel burner 110a and the solid fuel burner 120a are located at the same position on the wall surface 11a when the combustion furnace 11 is viewed in plan along the vertical direction VD. The ammonia fuel burner 110b and the solid fuel burner 120b are located at the same position on the wall surface 11b when the combustion furnace 11 is viewed in plan along the vertical direction VD. The ammonia fuel burner 110c and the solid fuel burner 120c are located at the same position on the wall surface 11c when the combustion furnace 11 is viewed in plan along the vertical direction VD. The ammonia fuel burner 110d and the solid fuel burner 120d are located at the same position on the wall surface 11d when the combustion furnace 11 is viewed in plan along the vertical direction VD.

[0042] The combustion burner 100A shown in Figure 2 has four ammonia fuel burners 110a, 110b, 110c, and 110d attached to the four walls 11a, 11b, 11c, and 11d that form the combustion furnace 11, and employs a swirling combustion method that forms a swirling flame flow, but other methods may also be used. For example, a counter-combustion method may be used in which multiple ammonia fuel burners are arranged on each of a pair of opposing walls in the combustion furnace 11.

[0043] Next, referring to FIG. 4, the arrangement of the combustion burners 100A, 100B, 100C, 100D, 100E, 100F included in the combustion device 12 of the boiler 10 of the present embodiment will be described. FIG. 4 is a partially enlarged view of the combustion furnace 11 shown in FIG. 1. As shown in FIG. 4, the boiler 10 of the present embodiment includes a plurality of combustion burners 100B, 100D, 100F that inject and burn solid fuel into the combustion furnace 11 from a plurality of locations around the axis Z at each of a plurality of first arrangement positions P1a, P1b, P1c arranged at intervals in the vertical direction VD along the axis Z.

[0044] In the present embodiment, the flow direction FD of the combustion gas generated by the combustion of the pulverized fuel and the ammonia fuel in the combustion device 12 coincides with the vertical direction VD. The combustion burner 100F is arranged at the first arrangement position P1a. The combustion burner 100D is arranged at the first arrangement position P1b on the downstream side of the first arrangement position P1a in the flow direction FD. The combustion burner 100B is arranged at the first arrangement position P1c on the downstream side of the first arrangement position P1b in the flow direction FD.

[0045] The boiler 10 of the present embodiment includes a plurality of combustion burners 100A, 100C, 100E that inject and burn ammonia fuel into the combustion furnace 11 from a plurality of locations around the axis Z at each of a plurality of second arrangement positions P2a, P2b, P2c arranged at intervals in the vertical direction VD along the axis Z.

[0046] The combustion burner 100E is arranged at the second arrangement position P2a. The combustion burner 100C is arranged at the second arrangement position P2b on the downstream side of the second arrangement position P2a in the flow direction FD. The combustion burner 100A is arranged at the second arrangement position P2c on the downstream side of the second arrangement position P2b in the flow direction FD.

[0047] The furnace bottom 11f shown in FIG. 4 is the lowest portion of the combustion furnace 11 in the vertical direction VD. The distances in the flow direction FD from the furnace bottom 11f to the combustion burners 100F, 100D, 100B are L1a, L1b, L1c, respectively. The distances in the flow direction FD from the furnace bottom 11f to the combustion burners 100E, 100C, 100A are L2a, L2b, L2c, respectively.

[0048] As shown in Figure 4, among the multiple first placement positions P1a, P1b, and P1c where the combustion burners 100B, 100D, and 100F that inject fine fuel are located, the first placement position P1a, which is the most upstream in the flow direction FD, is further upstream in the flow direction FD than the second placement position P2a, which is the most upstream in the flow direction FD among the multiple second placement positions P2a, P2b, and P2c where the combustion burners 100A, 100C, and 100E that inject ammonia fuel are located.

[0049] Next, with reference to Figure 5, the control method for the boiler 10 of this embodiment will be described. Figure 5 is a flowchart showing the control method for the boiler 10 according to one embodiment of the present disclosure. Figure 5 shows the control method for the boiler 10 when performing a co-firing operation in which fine fuel is injected from all of the multiple combustion burners 100B, 100D, and 100F, and ammonia fuel is injected from all of the multiple combustion burners 100A, 100C, and 100E.

[0050] In steps S101 and S102, a start operation is performed that switches from a fire extinguishing state, in which no fine fuel is injected from any of the multiple combustion burners 100B, 100D, and 100F, and no ammonia fuel is injected from any of the multiple combustion burners 100A, 100C, and 100E, to a mixed combustion operation.

[0051] In step S101, the control unit 60 controls the solid fuel adjustment units 31a, 32a, and 33a to start injecting fine fuel from all of the combustion burners 100B, 100D, and 100F. For example, the control unit 60 controls the solid fuel adjustment units 31a, 32a, and 33a to start injecting fine fuel from the upstream side of the combustion gas flow direction FD in the order of combustion burner 100F, combustion burner 100D, and combustion burner 100B.

[0052] In step S102, the control unit 60 controls the ammonia fuel adjustment units 51a, 52a, and 53a to start injecting ammonia fuel from all of the combustion burners 100A, 100C, and 100E. For example, the control unit 60 controls the ammonia fuel adjustment units 51a, 52a, and 53a to start injecting ammonia fuel in the order of combustion burner 100E, combustion burner 100C, and combustion burner 100A, starting from the upstream side of the combustion gas flow direction FD.

[0053] In step S101, injection of fine fuel is started from all of the multiple combustion burners 100B, 100D, and 100F. Subsequently, in step S102, injection of ammonia fuel is started from all of the multiple combustion burners 100A, 100C, and 100E. This results in a mixed-fuel operation in which fuel is injected from all of the combustion burners 100A, 100B, 100C, 100D, 100E, and 100F. In this embodiment, the control unit 60 controls the solid fuel adjustment units 31a, 32a, 33a and the ammonia fuel adjustment units 51a, 52a, 53a so that, for example, the proportion of ammonia fuel is 10% or more and 60% or less in terms of calorific value (calories).

[0054] As shown in Figure 4, the combustion burner 100F is positioned at the upstream end of the flow direction FD. In this manner, the control unit 60 controls the solid fuel adjustment units 31a, 32a, 33a and the ammonia fuel adjustment units 51a, 52a, 53a so that the fuel injected at the upstream end of the flow direction FD becomes pulverized fuel during co-firing operation.

[0055] The reason for initiating the injection of pulverized fuel in step S101, and then initiating the injection of ammonia fuel in step S102, is to bring the ambient temperature at the second placement positions P2a, P2b, and P2c where the combustion burners 100A, 100C, and 100E are located to a temperature sufficient for the combustion of ammonia and the decomposition of nitrous oxide produced during the ammonia combustion process.

[0056] When executing the startup operations of steps S101 and S102, the control unit 60 controls the solid fuel adjustment units 31a, 32a, and 33a so that the ambient temperature at the second placement positions P2a, P2b, and P2c where the combustion burners 100A, 100C, and 100E are located becomes 1000°C or higher at the timing when the supply of ammonia fuel to the combustion burners 100A, 100C, and 100E is started.

[0057] For example, when the control unit 60 controls the ammonia fuel adjustment unit 53a to inject ammonia fuel first from combustion burner 100E among combustion burners 100A, 100C, and 100E, it adjusts the solid fuel adjustment unit 33a so that the ambient temperature at the second position P2a where combustion burner 100E is located becomes 1000°C or higher. In this case, the control unit 60 injects fine fuel from combustion burner 100F prior to the injection of ammonia fuel from combustion burner 100E, and controls the system to inject ammonia fuel from combustion burner 100E after the ambient temperature at the second position P2a has reached 1000°C or higher.

[0058] The reason for setting the ambient temperature at the second placement positions P2a, P2b, and P2c to 1000°C or higher is to sufficiently promote the combustion of ammonia contained in the ammonia fuel and the decomposition of nitrous oxide produced during the ammonia combustion process. Since the decomposition of nitrous oxide is rapidly promoted when the ambient temperature exceeds 900°C, it is preferable to set it to 1000°C or higher in order to ensure sufficient decomposition. Furthermore, it is more preferable to set the ambient temperature at the second placement positions P2a, P2b, and P2c to 1100°C or higher, and even more preferable to set it to 1200°C or higher.

[0059] Figure 6 shows the relationship between the distance from the furnace bottom 11f of the combustion furnace 11 and the temperature. In the example shown in Figure 6, fine fuel is injected into the combustion furnace 11 from all of the combustion burners 100B, 100D, and 100F, and ammonia fuel is injected into the combustion furnace 11 from all of the combustion burners 100A, 100C, and 100E in a mixed combustion operation.

[0060] As shown in Figure 6, when the distance from the furnace bottom 11f exceeds L2a to the second position P2a where the combustion burner 100E that injects ammonia fuel is located, the ambient temperature inside the combustion furnace 11 exceeds 1400°C. Also, when the distance from the furnace bottom 11f exceeds L1c to the first position P1c where the combustion burner 100B that injects fine fuel is located, the ambient temperature inside the combustion furnace 11 becomes close to 1600°C.

[0061] Under the operating conditions shown in Figure 6, the ambient temperature at the second placement positions P2a, P2b, and P2c where the combustion burners 100A, 100C, and 100E are located will be 1000°C or higher. This will sufficiently promote the combustion of ammonia contained in the ammonia fuel injected from the combustion burners 100A, 100C, and 100E, as well as the decomposition of nitrous oxide produced during the ammonia combustion process.

[0062] In the co-firing operation described above, the injection of fine fuel is started from all of the combustion burners 100B, 100D, and 100F, and then in step S102, the injection of ammonia fuel is started from all of the combustion burners 100A, 100C, and 100E. However, other co-firing operations are also possible.

[0063] For example, the injection of fine fuel may be started from at least one of the multiple combustion burners 100B, 100D, and 100F, and then in step S102, the injection of ammonia fuel may be started from at least one of the multiple combustion burners 100A, 100C, and 100E.

[0064] In this case, the control unit 60 controls the solid fuel adjustment units 31a, 32a, 33a and the ammonia fuel adjustment units 51a, 52a, 53a so that in co-firing operation, the fuel injected at the upstream end of the flow direction FD becomes pulverized fuel. When the control unit 60 executes the startup operations of steps S101 and S102, it controls the solid fuel adjustment units 31a, 32a, 33a and the ammonia fuel adjustment units 51a, 52a, 53a so that the timing of starting to supply pulverized fuel to the combustion burners 100B, 100D, 100F, which are located at the upstream end of the flow direction FD among the plurality of first placement positions P1a, P1b, P1c, is earlier than the timing of starting to supply ammonia fuel to each of the plurality of combustion burners 100A, 100C, 100E.

[0065] In step S103, the control unit 60 determines whether to continue the co-firing operation. If the answer is YES, the process proceeds to step S104; otherwise, the process proceeds to step S106.

[0066] In step S104, the control unit 60 controls the solid fuel adjustment units 31a, 32a, and 33a to adjust the supply amount of fine fuel injected from the combustion burners 100B, 100D, and 100F. In step S105, the control unit 60 controls the ammonia fuel adjustment units 51a, 52a, and 52a to adjust the supply amount of ammonia fuel injected from the combustion burners 100A, 100C, and 100E.

[0067] When executing steps S104 and S105, the control unit 60 controls the solid fuel adjustment units 31a, 32a, 33a and the ammonia fuel adjustment units 51a, 52a, 53a so that the ambient temperature at the second placement positions P2a, P2b, P2c where the combustion burners 100A, 100C, 100E are located is 1000°C or higher.

[0068] In step S106, the control unit 60 controls the ammonia fuel adjustment units 51a, 52a, and 53a to stop the injection of ammonia fuel from the multiple combustion burners 100A, 100C, and 100E. For example, the control unit 60 controls the ammonia fuel adjustment units 51a, 52a, and 53a to stop the injection of ammonia fuel in the order of combustion burner 100A, combustion burner 100C, and combustion burner 100E, starting from the downstream side of the combustion gas flow direction FD.

[0069] In step S107, the control unit 60 controls the solid fuel adjustment units 31a, 32a, and 33a to stop the injection of fine fuel from the multiple combustion burners 100B, 100D, and 100F. For example, the control unit 60 controls the solid fuel adjustment units 31a, 32a, and 33a to stop the injection of fine fuel from the combustion burner 100B, combustion burner 100D, and combustion burner 100F in the order of downstream side in the combustion gas flow direction FD.

[0070] The reason for stopping the injection of ammonia fuel in step S106, and then stopping the injection of pulverized fuel in step S107, is to maintain the ambient temperature at the second positioning locations P2a, P2b, and P2c where the combustion burners 100A, 100C, and 100E are located at a temperature sufficient for the combustion of ammonia and the decomposition of nitrous oxide produced during the ammonia combustion process. When the injection of ammonia fuel is stopped, the injection of pulverized fuel continues, so the ambient temperature at the second positioning locations P2a, P2b, and P2c can be maintained at a temperature sufficient for the combustion of ammonia and the decomposition of nitrous oxide produced during the ammonia combustion process.

[0071] The operation and effects of the boiler 10 of this embodiment, as described above, will now be explained. According to the boiler 10 of this embodiment, when performing a co-firing operation in which solid fuel is injected from at least one of the multiple combustion burners 100B, 100D, and 100F, and ammonia fuel is injected from at least one of the multiple combustion burners 100A, 100C, and 100E, the fuel injected at the upstream end of the flow direction FD through which the combustion gas flows becomes pulverized fuel. Since the combustion gas generated by the combustion of the pulverized fuel flows from the upstream to the downstream end of the flow direction FD, the ambient temperature at the second position where the combustion burners 100A, 100C, and 100E are located rises compared to when there is no combustion gas flow, and the combustion of ammonia fuel and the decomposition of nitrous oxide are promoted. In addition, since the ammonia fuel is guided from the upstream to the downstream end of the flow direction FD by the flow of combustion gas, it is possible to appropriately prevent unburned ammonia and nitrous oxide from accumulating on the upstream side in a predetermined direction.

[0072] In the boiler 10 of this embodiment, the first position P1a of the combustion burner 100F, which is located on the uppermost side of the flow direction FD and injects pulverized fuel, is upstream of the second position P2a of the combustion burner 100E, which is located on the uppermost side of the flow direction FD and injects ammonia fuel. Therefore, even when pulverized fuel is injected from all combustion burners 100B, 100D, and 100F, and ammonia fuel is injected from all combustion burners 100A, 100C, and 100E, the fuel injected at the uppermost side of the flow direction FD through which the combustion gas flows is pulverized fuel. As a result, the ambient temperature at the second position where the combustion burners 100A, 100C, and 100E are located rises, promoting the combustion of ammonia fuel and the decomposition of nitrous oxide. Furthermore, since the ammonia fuel is guided from the upstream side to the downstream side of the flow direction FD by the flow of combustion gas, it is possible to appropriately prevent the accumulation of unburned ammonia and nitrous oxide on the upstream side of the flow direction FD.

[0073] According to the boiler 10 of this embodiment, when performing a startup operation, the timing at which the supply of pulverized fuel begins to the combustion burner 100F located on the upstream side of the flow direction FD among the multiple first placement positions P1a, P1b, and P1c is earlier than the timing at which the supply of ammonia fuel begins to any of the multiple combustion burners 100A, 100C, and 100E. Therefore, at the timing at which the supply of ammonia fuel begins to any of the multiple combustion burners 100A, 100C, and 100E, the combustion gas generated by the combustion of pulverized fuel flows from the upstream side to the downstream side of the flow direction FD.

[0074] Furthermore, the combustion burner that injects fine fuel (ignition operation) during startup only needs to be located upstream of the combustion burner that injects ammonia fuel in the flow direction FD. The combustion burner that injects fine fuel during startup may be the combustion burner 100F located at the lowest stage in the vertical direction VD of the boiler 10, or, if the combustion burner 100F is not used during startup, it may be another combustion burner located downstream of it in the flow direction FD.

[0075] As a result, the ambient temperature at the location where the combustion burners 100A, 100C, and 100E are positioned rises compared to when there is no combustion gas flow, promoting the combustion of ammonia fuel and the decomposition of nitrous oxide. In addition, because the ammonia fuel is guided from the upstream side to the downstream side of the flow direction FD by the combustion gas flow, it is possible to effectively prevent the accumulation of unburned ammonia and nitrous oxide on the upstream side of the flow direction FD.

[0076] According to the boiler 10 of this embodiment, at the timing when the supply of ammonia fuel to the combustion burners 100A, 100C, and 100E is started, the ambient temperature at the second positioning positions P2a, P2b, and P2c where the combustion burners 100A, 100C, and 100E are located becomes 1000°C or higher. This ensures reliable combustion of the ammonia fuel and reliable promotion of nitrous oxide decomposition.

[0077] [First Modification] In the above description, the combustion burner located at the downstream end of the flow direction FD was defined as a combustion burner 100A that injects ammonia fuel, but other configurations are also possible. For example, the combustion burner 100A may be removed from the combustion device 12 of the boiler 10 shown in Figure 4, and the combustion burner located at the downstream end of the flow direction FD may be defined as a combustion burner 100B that injects pulverized fuel. In this case, the first position P1c, which is the downstream end of the flow direction FD among the plurality of first positioning positions P1a, P1b, P1c where the combustion burners 100B, 100D, and 100F are located, is downstream of the flow direction FD than the second position P2b, which is the downstream end of the flow direction FD among the plurality of second positioning positions P2a, P2b where the combustion burners 100C and 100E are located.

[0078] With the boiler 10 described above, the first position P1c of the combustion burner 100B, which is located at the downstream end of the flow direction FD and injects fine fuel, is located downstream of the second position P2b of the combustion burner 100C, which is located at the downstream end of the flow direction FD and injects ammonia fuel. Therefore, it is possible to ensure sufficient combustion time for the ammonia fuel injected from the combustion burner 100C and prevent unburned ammonia fuel and nitrous oxide from flowing out to the downstream side of the flow direction FD without being decomposed.

[0079] Furthermore, the combustion burner that injects (ignites) the fine fuel only needs to be positioned downstream in the flow direction FD from the combustion burner that injects the ammonia fuel. The combustion burner that injects the fine fuel may be the combustion burner 100B installed at the top in the vertical direction VD of the boiler 10, or if combustion burner 100B is not used, it may be another combustion burner positioned upstream in the flow direction FD from it.

[0080] [Second Modification] In the above description, the control unit 60 is shown to perform a co-firing operation in which fine fuel is injected from all of the multiple combustion burners 100B, 100D, and 100F, and ammonia fuel is injected from all of the multiple combustion burners 100A, 100C, and 100E. However, other configurations are also possible. For example, the control unit 60 may perform a co-firing operation in which fine fuel is not injected from at least one of the multiple combustion burners 100B, 100D, and 100F, and ammonia fuel is not injected from at least one of the multiple combustion burners 100A, 100C, and 100E. Such a co-firing operation is performed, for example, when operating the boiler 10 at a partial load lower than the rated load.

[0081] The control unit 60 may, for example, perform a co-firing operation in which ammonia fuel is injected only from combustion burner 100E among combustion burners 100A, 100C, and 100E, and fine fuel is injected only from combustion burner 100F among combustion burners 100B, 100D, and 100F. In this case, the control unit 60 controls the injection of fine fuel from combustion burner 100F prior to the injection of ammonia fuel from combustion burner 100E, and then injects ammonia fuel from combustion burner 100E after the ambient temperature at the second position P2a reaches 1000°C or higher.

[0082] The control methods for the boiler, power generation equipment, and combustion furnace described in each embodiment described above can be understood, for example, as follows. The combustion furnace according to the first aspect of this disclosure is capable of co-firing ammonia fuel containing ammonia and a first fuel different from the ammonia fuel, and includes a plurality of first fuel burners (100B, 100D, 100F) that inject and burn the first fuel into the combustion furnace from multiple locations around the axis at each of a plurality of first arrangement positions (P1a, P1b, P1c) arranged at intervals in a predetermined direction (VD), a plurality of ammonia fuel burners (100A, 100C, 100E) that inject and burn ammonia fuel into the combustion furnace from multiple locations around the axis at each of second arrangement positions (P2a, P2b, P2c) arranged at intervals in the predetermined direction and different from the first arrangement positions, and a first fuel adjustment unit (31a, 32a, 3) that adjusts the amount of the first fuel supplied to the first fuel burners. 3a) A boiler (10) comprising: an ammonia fuel adjustment unit (51a, 52a, 53a) that adjusts the amount of ammonia fuel supplied to the ammonia fuel burner; and a control unit (60) that controls the first fuel adjustment unit and the ammonia fuel adjustment unit, wherein the combustion gas generated by the combustion of the first fuel and the ammonia fuel flows in the combustion furnace in a predetermined direction and is discharged to the outside, wherein the control unit controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that the fuel injected at the upstream end in the predetermined direction is the first fuel when performing a co-firing operation in which the first fuel is injected from at least one of the plurality of first fuel burners and the ammonia fuel is injected from at least one of the plurality of ammonia fuel burners.

[0083] According to the combustion furnace of the first aspect of this disclosure, when performing a co-firing operation in which a first fuel is injected from at least one of a plurality of first fuel burners and ammonia fuel is injected from at least one of a plurality of ammonia fuel burners, the fuel injected at the upstream end in a predetermined direction through which the combustion gas flows becomes the first fuel. Since the combustion gas generated by the combustion of the first fuel flows from the upstream end to the downstream end in a predetermined direction, the ambient temperature at the second position where the ammonia fuel burner is located rises compared to when there is no combustion gas flow, and the combustion of ammonia fuel and the decomposition of ammonia and nitrous oxide are promoted. In addition, since the ammonia fuel is guided from the upstream end to the downstream end in a predetermined direction by the flow of combustion gas, it is possible to appropriately prevent the accumulation of unburned ammonia and nitrous oxide on the upstream side in a predetermined direction.

[0084] A combustion furnace according to a second aspect of the present disclosure further comprises the following configuration in the first aspect: that, among the plurality of first arrangement positions in which the first fuel burner is arranged, the position furthest upstream in the predetermined direction is further upstream in the predetermined direction than the position furthest upstream in the plurality of second arrangement positions in which the ammonia fuel burner is arranged.

[0085] According to the combustion furnace of the second aspect of this disclosure, the first position of the first fuel burner located at the upstream end in a predetermined direction is upstream of the second position of the ammonia fuel burner located at the upstream end in a predetermined direction. Therefore, even when the first fuel is injected from all the first fuel burners and ammonia fuel is injected from all the ammonia fuel burners, the fuel injected at the upstream end in the predetermined direction through which the combustion gas flows becomes the first fuel. This makes it possible to appropriately prevent the accumulation of unburned ammonia and nitrous oxide upstream in the predetermined direction.

[0086] A combustion furnace according to a third aspect of the present disclosure further comprises the following configuration in a second aspect. That is, when the control unit performs a startup operation to switch from a fire extinguishing state in which the first fuel is not injected from all of the plurality of first fuel burners and the ammonia fuel is not injected from all of the plurality of ammonia fuel burners to the co-firing operation, the control unit controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that the timing at which the supply of the first fuel is started to the first fuel burner located on the upstream side in the predetermined direction among the plurality of first arrangement positions of the first fuel burners to be started is earlier than the timing at which the supply of the ammonia fuel is started to each of the plurality of ammonia fuel burners.

[0087] According to the combustion furnace of the third aspect of this disclosure, when the startup operation is performed, the timing at which the supply of the first fuel begins to the first fuel burner located furthest upstream in a predetermined direction among a plurality of first placement positions of the first fuel burner to be started is earlier than the timing at which the supply of ammonia fuel begins to each of the plurality of ammonia fuel burners. Therefore, at the timing at which the supply of ammonia fuel begins to each of the plurality of ammonia fuel burners, the combustion gas generated by the combustion of the first fuel flows from the upstream side to the downstream side in the predetermined direction. As a result, the ambient temperature at the location where the ammonia fuel burner is placed rises compared to when there is no flow of combustion gas, and the combustion of ammonia fuel is promoted. In addition, because the ammonia fuel is guided from the upstream side to the downstream side in the predetermined direction by the flow of combustion gas, it is possible to appropriately prevent the accumulation of unburned ammonia and nitrous oxide on the upstream side in the predetermined direction.

[0088] A combustion furnace according to a fourth aspect of the present disclosure further comprises the following configuration in a third aspect: When the control unit performs the startup operation, it controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that the ambient temperature at the second position where the ammonia fuel burner is located becomes 1000°C or higher at the timing when the supply of the ammonia fuel to the ammonia fuel burner is started.

[0089] According to the combustion furnace of the fourth aspect of this disclosure, the ambient temperature at the second position where the ammonia fuel burner is located becomes 1000°C or higher at the time when the supply of ammonia fuel to the ammonia fuel burner is started, thereby ensuring reliable combustion of the ammonia fuel and reliably promoting the decomposition of nitrous oxide.

[0090] A combustion furnace according to a fifth aspect of the present disclosure further comprises the following configuration in any of the first to fourth aspects: that, among the plurality of first arrangement positions in which the first fuel burner is arranged, the position furthest downstream in the predetermined direction is downstream in the predetermined direction of the plurality of second arrangement positions in which the ammonia fuel burner is arranged.

[0091] According to the combustion furnace of the fifth aspect of this disclosure, the first position of the first fuel burner located at the downstream end in a predetermined direction is downstream of the second position of the ammonia fuel burner located at the downstream end in a predetermined direction. This ensures sufficient burning time for the ammonia fuel and prevents unburned ammonia fuel and nitrous oxide from flowing downstream in the predetermined direction.

[0092] A combustion furnace according to a sixth aspect of the present disclosure further comprises the following configuration in any of the first to fourth aspects: The control unit performs the co-combustion operation without injecting the first fuel from at least one of the plurality of first fuel burners and without injecting the ammonia fuel from at least one of the plurality of ammonia fuel burners.

[0093] According to the combustion furnace of the sixth aspect of this disclosure, even when co-firing is performed at partial load in which the first fuel is not injected from at least one of the plurality of first fuel burners and ammonia fuel is not injected from at least one of the plurality of ammonia fuel burners, it is possible to appropriately prevent unburned ammonia and nitrous oxide from accumulating on the upstream side in a predetermined direction.

[0094] A boiler according to the seventh aspect of this disclosure comprises a combustion furnace as described in any of the above.

[0095] The power generation equipment according to the eighth aspect of this disclosure comprises a boiler equipped with a combustion furnace according to any of the first to fourth aspects, a steam turbine driven by steam generated in the boiler, and a generator connected to the steam turbine.

[0096] According to the power generation equipment of the eighth aspect of this disclosure, by changing the amount of ammonia fuel supplied to the ammonia fuel burner, the load change rate of the boiler can be increased compared to the case where only the supply amount of the first fuel is changed.

[0097] A combustion furnace control method according to a ninth aspect of the present disclosure, wherein the combustion furnace is capable of co-firing ammonia fuel containing ammonia and a first fuel different from the ammonia fuel, and comprises a plurality of first fuel burners that inject and burn the first fuel into the combustion furnace from a plurality of locations around the axis at each of a plurality of first arrangement positions arranged at intervals in a predetermined direction, a plurality of ammonia fuel burners that inject and burn ammonia fuel into the combustion furnace from a plurality of locations around the axis at each of second arrangement positions arranged at intervals in the predetermined direction and different from the first arrangement positions, and a first fuel that adjusts the supply amount of the first fuel supplied to the first fuel burners The system includes an adjustment unit and an ammonia fuel adjustment unit that adjusts the amount of ammonia fuel supplied to the ammonia fuel burner, and when performing a co-firing operation in which the combustion gas generated by the combustion of the first fuel and the ammonia fuel is circulated in the combustion furnace in a predetermined direction and discharged to the outside, the first fuel is injected from at least one of the plurality of first fuel burners, and the ammonia fuel is injected from at least one of the plurality of ammonia fuel burners, the system includes a control step that controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that the fuel injected at the upstream end in the predetermined direction becomes the first fuel.

[0098] According to the combustion furnace control method of the eighth aspect of this disclosure, when performing a co-firing operation in which a first fuel is injected from at least one of a plurality of first fuel burners and ammonia fuel is injected from at least one of a plurality of ammonia fuel burners, the fuel injected at the upstream end of a predetermined direction in which the combustion gas flows becomes the first fuel. Since the combustion gas generated by the combustion of the first fuel flows from the upstream end to the downstream end of the predetermined direction, the ambient temperature at the location where the ammonia fuel burner is positioned rises compared to when there is no combustion gas flow, and the combustion of the ammonia fuel is promoted. In addition, since the ammonia fuel is guided from the upstream end to the downstream end of the predetermined direction by the flow of combustion gas, it is possible to appropriately prevent the accumulation of unburned ammonia and nitrous oxide on the upstream side of the predetermined direction.

[0099] 10 Boiler 11 Combustion furnace 11a, 11b, 11c, 11d Wall 11f Furnace bottom 12 Combustion apparatus 13 Flue 26, 27, 28 Fine fuel supply pipe 31, 32, 33 Crusher 31a, 32a, 33a Solid fuel adjustment section 31b, 32b, 33b Solid fuel supply pipe 50 Ammonia fuel supply section 51, 52, 53 Ammonia fuel supply pipe 51a, 52a, 53a Ammonia fuel adjustment section 60 Control section 100A, 100C, 100E Combustion burner (ammonia fuel burner) 100B, 100D, 100F Combustion burner (solid fuel burner) 110a, 110b, 110c, 110d Ammonia fuel burner 120a, 120b, 120c, 120d Solid fuel burner FD Flow direction P1a, P1b, P1c First arrangement position P2a, P2b, P2c Second arrangement position VD Vertical direction Z Axis

Claims

1. A combustion furnace capable of co-firing ammonia fuel containing ammonia and a first fuel different from the ammonia fuel, comprising: a plurality of first fuel burners that inject and burn the first fuel into the combustion furnace from a plurality of locations at each of a plurality of first arrangement positions arranged at intervals in a predetermined direction; a plurality of ammonia fuel burners that inject and burn the ammonia fuel into the combustion furnace from a plurality of locations at each of second arrangement positions arranged at intervals in the predetermined direction and different from the first arrangement positions; a first fuel adjustment unit that adjusts the amount of the first fuel supplied to the first fuel burners; an ammonia fuel adjustment unit that adjusts the amount of the ammonia fuel supplied to the ammonia fuel burners; and a control unit that controls the first fuel adjustment unit and the ammonia fuel adjustment unit, wherein the combustion gas generated by the combustion of the first fuel and the ammonia fuel is circulated in the predetermined direction in the combustion furnace and discharged to the outside, The control unit controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that when performing a co-firing operation in which the first fuel is injected from at least one of the plurality of first fuel burners and the ammonia fuel is injected from at least one of the plurality of ammonia fuel burners, the fuel injected at the upstream end in the predetermined direction becomes the first fuel.

2. The combustion furnace according to claim 1, wherein the upstreammost position in the predetermined direction among the plurality of first arrangement positions in which the first fuel burner is arranged is further upstream in the predetermined direction than the upstreammost position in the predetermined direction among the plurality of second arrangement positions in which the ammonia fuel burner is arranged.

3. The combustion furnace according to claim 2, wherein the control unit controls the first fuel adjustment unit and the ammonia fuel adjustment unit to start supplying the first fuel to the first fuel burner located on the upstream side in the predetermined direction among the plurality of first arrangement positions of the first fuel burners to start, when performing a start operation to switch from a fire extinguishing state in which the first fuel is not injected from all of the plurality of first fuel burners and the ammonia fuel is not injected from all of the plurality of ammonia fuel burners to the co-firing operation, so that the timing of starting to supply the first fuel to the first fuel burner located on the upstream side in the predetermined direction among the plurality of first arrangement positions of the first fuel burners to start is earlier than the timing of starting to supply the ammonia fuel to each of the plurality of ammonia fuel burners.

4. The combustion furnace according to claim 3, wherein the control unit controls the first fuel adjustment unit and the ammonia fuel adjustment unit so that the ambient temperature at the second position where the ammonia fuel burner is located becomes 1000°C or higher at the timing when the supply of the ammonia fuel to the ammonia fuel burner is started when the start operation is performed by the control unit.

5. The combustion furnace according to any one of claims 1 to 4, wherein the most downstream position in the predetermined direction among the plurality of first positioning locations where the first fuel burner is arranged is further downstream in the predetermined direction than the most downstream position in the predetermined direction among the plurality of second positioning locations where the ammonia fuel burner is arranged.

6. The combustion furnace according to any one of claims 1 to 4, wherein the control unit performs the co-firing operation without injecting the first fuel from at least one of the plurality of first fuel burners and without injecting the ammonia fuel from at least one of the plurality of ammonia fuel burners.

7. A boiler comprising a combustion furnace according to any one of claims 1 to 4.

8. A power generation facility comprising: a boiler equipped with a combustion furnace according to any one of claims 1 to 4; a steam turbine driven by steam generated in the boiler; and a generator connected to the steam turbine.

9. A method for controlling a combustion furnace capable of co-firing an ammonia fuel containing ammonia and a first fuel different from the ammonia fuel, wherein the combustion furnace comprises: a plurality of first fuel burners that inject and burn the first fuel into the combustion furnace from a plurality of locations at each of a plurality of first arrangement positions arranged at intervals in a predetermined direction; a plurality of ammonia fuel burners that inject and burn the ammonia fuel into the combustion furnace from a plurality of locations at each of second arrangement positions arranged at intervals in the predetermined direction and different from the first arrangement positions; a first fuel adjustment unit that adjusts the amount of the first fuel supplied to the first fuel burners; and an ammonia fuel adjustment unit that adjusts the amount of the ammonia fuel supplied to the ammonia fuel burners, wherein the combustion gas generated by the combustion of the first fuel and the ammonia fuel is circulated in the predetermined direction in the combustion furnace and discharged to the outside. A control method for a combustion furnace, comprising a control step of controlling the first fuel adjustment unit and the ammonia fuel adjustment unit so that the fuel injected at the upstream end in a predetermined direction becomes the first fuel when performing a co-firing operation in which the first fuel is injected from at least one of the plurality of first fuel burners and the ammonia fuel is injected from at least one of the plurality of ammonia fuel burners.

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