Combustion system

Abstract

In order to optimize combustion in a combustor, provided is a combustion system including: a first gaseous ammonia line which is connected to a combustor, and through which gaseous ammonia flows; a first liquid ammonia line which is connected to the combustor, and through which liquid ammonia flows; a second gaseous ammonia line which is connected to the combustor, and through which gaseous ammonia flows; a second liquid ammonia line which is connected to the combustor, and through which liquid ammonia flows; and a control device that controls a flow rate of ammonia flowing through each of the first gaseous ammonia line, the first liquid ammonia line, the second gaseous ammonia line, and the second liquid ammonia line.

Description

BACKGROUNDTECHNICAL FIELD

[0001] The present disclosure relates to a combustion system. The present application claims the benefit of priority to Japanese Patent Application No. 2025-067381 filed on Apr.16, 2025, the contents of which are incorporated herein by reference.2. DESCRIPTION OF THE RELATED ART

[0002] In recent years, there is a demand for reduction in carbon dioxide (CO2) emissions to prevent global warming. Thus, for example, in Patent Literature 1, there is disclosed a technology of supplying liquid ammonia and gaseous ammonia as fuel for a gas turbine.

[0003] Patent Literature 1: Japanese Patent Application Laid-open No. 2024-105645

[0004] In a technology of burning ammonia as described in Patent Literature 1, development of a technology capable of optimizing combustion in a combustor is desired.SUMMARY

[0005] In view of the above-mentioned problem, the present disclosure has an object to provide a combustion system capable of optimizing combustion in a combustor.

[0006] In order to solve the above-mentioned problem, according to at least one aspect of the present disclosure, there is provided a combustion system including: a first gaseous ammonia line which is connected to a combustor, and through which gaseous ammonia flows; a first liquid ammonia line which is connected to the combustor, and through which liquid ammonia flows; a second gaseous ammonia line which is connected to the combustor, and through which gaseous ammonia flows; a second liquid ammonia line which is connected to the combustor, and through which liquid ammonia flows; and a control device that controls a flow rate of ammonia flowing through each of the first gaseous ammonia line, the first liquid ammonia line, the second gaseous ammonia line, and the second liquid ammonia line.

[0007] The above-mentioned combustion system may further include: at least one first burner provided in the combustor, and connected to each of the first gaseous ammonia line and the first liquid ammonia line; and at least one second burner provided in the combustor, and connected to each of the second gaseous ammonia line and the second liquid ammonia line, and the control device may perform control such that the ammonia is injected into the combustor from at least the at least one first burner at the time of ignition of the combustor.

[0008] An injection direction of the ammonia of the at least one first burner may be different from an injection direction of the ammonia of the at least one second burner.

[0009] The above-mentioned combustion system may further include an ignition device that generates a spark in the combustor, and the injection direction of the ammonia of the at least one first burner may be a direction facing the spark.

[0010] The at least one first burner and the at least one second burner may inject an oxidant gas together with the ammonia, and an amount of the oxidant gas injected from the at least one first burner may be smaller than an amount of the oxidant gas injected from the at least one second burner.

[0011] The control device may control the flow rate based on a concentration of a nitrogen oxide exhausted from the combustor.

[0012] The control device may control the flow rate based on a concentration of unburned ammonia exhausted from the combustor.

[0013] The control device may control the flow rate based on a temperature distribution of the combustor.

[0014] The control device may control the flow rate based on stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line or the second gaseous ammonia line to the combustor.

[0015] According to the at least one embodiment of the present disclosure, it becomes possible to optimize combustion in the combustor.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a schematic view for illustrating a combustion system according to at least one embodiment of the present disclosure.

[0017] FIG. 2 is a flowchart for illustrating an example of a flow of first processing performed by a control device in the at least one embodiment.

[0018] FIG. 3 is a flowchart for illustrating an example of a flow of Step S130 performed by the control device in the at least one embodiment.

[0019] FIG. 4 is a flowchart for illustrating an example of a flow of second processing performed by the control device in the at least one embodiment.DESCRIPTION OF THE EMBODIMENTS

[0020] Now, with reference to the attached drawings, at least one embodiment of the present disclosure is described in detail. The dimensions, materials, and other specific numerical values and the like represented in the at least one embodiment are merely examples used for facilitating the understanding of the disclosure, and do not limit the present disclosure unless otherwise particularly noted. Elements having substantially the same functions and configurations herein and in the drawings are denoted by the same reference symbols to omit redundant description thereof. Further, illustration of elements with no direct relationship to the present disclosure is omitted.1. Overview of Combustion System

[0021] First, an overview of a combustion system 100 according to at least one embodiment of the present disclosure is described with reference to FIG. 1. FIG. 1 is a schematic diagram for illustrating the combustion system 100 according to the at least one embodiment. The combustion system 100 according to the at least one embodiment is a gas turbine system corresponding to an example of a combustion system that generates energy by burning fuel. In particular, the combustion system 100 uses ammonia as fuel. This suppresses emission of carbon dioxide. Further, the combustion system 100 according to the at least one embodiment uses air as an oxidant gas for burning fuel.

[0022] As illustrated in FIG. 1, the combustion system 100 includes a gas turbine 110, a combustor 120, a generator 130, a first pump 140, a second pump 150, a vaporizer 160, a heat recovery steam generator 170, and an exhaust tower 180.

[0023] Further, the combustion system 100 includes, as flow passages through which fluids flow, an intake line 210, an exhaust line 212, a first gaseous ammonia line 214, a first liquid ammonia line 216, a second gaseous ammonia line 218, a second liquid ammonia line 220, a water line 222a, a steam line 222b, and a supply line 224.

[0024] Further, the combustion system 100 includes, as flow rate control valves that control flow rates of fluids flowing through the flow passages, a first flow rate control valve 310, a second flow rate control valve 312, a third flow rate control valve 314, a fourth flow rate control valve 316, a fifth flow rate control valve 318, and a sixth flow rate control valve 320.

[0025] Further, the combustion system 100 includes, as shut-off valves that open and close the flow passages, a first shut-off valve 330, a second shut-off valve 332, a third shut-off valve 334, and a fourth shut-off valve 336.

[0026] Further, the combustion system 100 includes, as sensors, a first gas analyzer 340, a second gas analyzer 342, a first thermometer 344, and a second thermometer 346.

[0027] Further, the combustion system 100 includes a control device 400 that controls each device included in the combustion system 100.

[0028] The gas turbine 110 includes a compressor 112 and a turbine 114. The compressor 112 and the turbine 114 rotate integrally. The compressor 112 and the turbine 114 are connected to each other by a shaft.

[0029] The compressor 112 is provided in the intake line 210 connected to the combustor 120. Air to be supplied to the combustor 120 flows through the intake line 210.

[0030] The turbine 114 is provided in the exhaust line 212 connected to the combustor 120. Exhaust gas discharged from the combustor 120 flows through the exhaust line 212. The exhaust gas discharged from the combustor 120 passes through the turbine 114 and is sent to a downstream side of the turbine 114 in the exhaust line 212. When the turbine 114 is rotated by the exhaust gas, rotational power is generated.

[0031] The generator 130 is connected to the gas turbine 110 (in one embodiment, the compressor 112 and the turbine 114). The rotational power generated by the gas turbine 110 is used for electric power generation by the generator 130. Electric power output from the generator 130 is supplied to, for example, an electric power system. The electric power system is a facility for supplying electric power from an electric power plant to electric power receiving facilities of consumers. The electric power system includes electric power plants, substations, electric power transmission networks, electric power distribution networks, and the like.

[0032] Air compressed by the compressor 112 is supplied from the intake line 210 to the combustor 120, and ammonia is supplied to the combustor 120 from one or a plurality of ammonia lines including at least one of the first gaseous ammonia line 214, the first liquid ammonia line 216, the second gaseous ammonia line 218, or the second liquid ammonia line 220. As described later, which ammonia line supplies ammonia to the combustor 120 and a supply amount of ammonia to be supplied to the combustor 120 are controlled by the control device 400 depending on the situation.

[0033] The first gaseous ammonia line 214 is a flow passage for supplying gaseous ammonia to the combustor 120. The first gaseous ammonia line 214 connects an ammonia supply source 350 and the combustor 120 to each other. Gaseous ammonia sent from the ammonia supply source 350 flows through the first gaseous ammonia line 214. For example, liquid ammonia is stored in the ammonia supply source 350. Further, the first gaseous ammonia line 214 is provided with, for example, the first pump 140 and the vaporizer 160. A suction side of the first pump 140 is connected to the ammonia supply source 350. A discharge side of the first pump 140 is connected to the vaporizer 160. In addition, liquid ammonia sent from the ammonia supply source 350 by the first pump 140 is vaporized by the vaporizer 160, and the gaseous ammonia thus generated is sent to the first gaseous ammonia line 214.

[0034] The first gaseous ammonia line 214 is provided with the first shut-off valve 330 and the first flow rate control valve 310. The first shut-off valve 330 and the first flow rate control valve 310 are provided on a downstream side of the vaporizer 160 and on an upstream side of the combustor 120 in the first gaseous ammonia line 214. The first shut-off valve 330 opens and closes a flow passage formed in the first gaseous ammonia line 214. The first flow rate control valve 310 is provided on a downstream side of the first shut-off valve 330. The first flow rate control valve 310 controls a flow rate (that is, a supply amount) of gaseous ammonia to be supplied to the combustor 120 through the first gaseous ammonia line 214. In one embodiment, with an opening degree of the first flow rate control valve 310 being adjusted, the supply amount of gaseous ammonia to be supplied to the combustor 120 through the first gaseous ammonia line 214 is adjusted.

[0035] The first liquid ammonia line 216 is a flow passage for supplying liquid ammonia to the combustor 120. The first liquid ammonia line 216 connects the ammonia supply source 350 and the combustor 120 to each other. Liquid ammonia sent from the ammonia supply source 350 flows through the first liquid ammonia line 216. For example, liquid ammonia is stored in the ammonia supply source 350. Further, the first liquid ammonia line 216 is provided with, for example, the second pump 150. A suction side of the second pump 150 is connected to the ammonia supply source 350. A discharge side of the second pump 150 is connected to the combustor 120. In addition, liquid ammonia is sent from the ammonia supply source 350 to the first liquid ammonia line 216 by the second pump 150.

[0036] The first liquid ammonia line 216 is provided with the second shut-off valve 332 and the second flow rate control valve 312. The second shut-off valve 332 opens and closes a flow passage formed in the first liquid ammonia line 216. The second flow rate control valve 312 is provided on a downstream side of the second shut-off valve 332. The second flow rate control valve 312 controls a flow rate (that is, a supply amount) of liquid ammonia to be supplied to the combustor 120 through the first liquid ammonia line 216. In one embodiment, with an opening degree of the second flow rate control valve 312 being adjusted, the supply amount of liquid ammonia to be supplied to the combustor 120 through the first liquid ammonia line 216 is adjusted.

[0037] The second gaseous ammonia line 218 is a flow passage for supplying gaseous ammonia to the combustor 120. The second gaseous ammonia line 218 connects the ammonia supply source 350 and the combustor 120 to each other. In the at least one embodiment, the second gaseous ammonia line 218 is connected to the ammonia supply source 350 via, for example, the first gaseous ammonia line 214. For example, the second gaseous ammonia line 218 connects a portion between the vaporizer 160 and the first shut-off valve 330 in the first gaseous ammonia line 214, and the combustor 120 to each other. Gaseous ammonia sent from the ammonia supply source 350 flows through the second gaseous ammonia line 218 via the first gaseous ammonia line 214.

[0038] The second gaseous ammonia line 218 is provided with the third shut-off valve 334 and the third flow rate control valve 314. The third shut-off valve 334 opens and closes a flow passage formed in the second gaseous ammonia line 218. The third flow rate control valve 314 is provided on a downstream side of the third shut-off valve 334. The third flow rate control valve 314 controls a flow rate (that is, a supply amount) of gaseous ammonia to be supplied to the combustor 120 through the second gaseous ammonia line 218. In one embodiment, with an opening degree of the third flow rate control valve 314 being adjusted, the supply amount of gaseous ammonia to be supplied to the combustor 120 through the second gaseous ammonia line 218 is adjusted.

[0039] The second liquid ammonia line 220 is a flow passage for supplying liquid ammonia to the combustor 120. The second liquid ammonia line 220 connects the ammonia supply source 350 and the combustor 120 to each other. In the at least one embodiment, the second liquid ammonia line 220 is connected to the ammonia supply source 350 via, for example, the first liquid ammonia line 216. For example, the second liquid ammonia line 220 connects a portion between the second pump 150 and the second shut-off valve 332 in the first liquid ammonia line 216, and the combustor 120 to each other. Liquid ammonia sent from the ammonia supply source 350 flows through the second liquid ammonia line 220 via the first liquid ammonia line 216.

[0040] The second liquid ammonia line 220 is provided with the fourth shut-off valve 336 and the fourth flow rate control valve 316. The fourth shut-off valve 336 opens and closes a flow passage formed in the second liquid ammonia line 220. The fourth flow rate control valve 316 is provided on a downstream side of the fourth shut-off valve 336. The fourth flow rate control valve 316 controls a flow rate (that is, a supply amount) of liquid ammonia to be supplied to the combustor 120 through the second liquid ammonia line 220. In one embodiment, with an opening degree of the fourth flow rate control valve 316 being adjusted, the supply amount of liquid ammonia to be supplied to the combustor 120 through the second liquid ammonia line 220 is adjusted.

[0041] The heat recovery steam generator 170 is provided on a downstream side of the turbine 114 in the exhaust line 212. The heat recovery steam generator 170 is provided with the steam line 222b. The steam line 222b is connected to the water line 222a. The water line 222a is a flow passage through which water flows. The steam line 222b is a flow passage through which steam flows. Water sent from the water line 222a to the steam line 222b is heated by the exhaust gas flowing through the exhaust line 212, and is vaporized to become gas (that is, steam). For example, the steam line 222b is connected to the vaporizer 160. Then, steam generated in the heat recovery steam generator 170 is sent to the vaporizer 160. Then, the vaporizer 160 uses the steam generated in the heat recovery steam generator 170 as a heat source to vaporize liquid ammonia. For example, in the vaporizer 160, heat exchange is performed between liquid ammonia and steam. As a result, in the vaporizer 160, liquid ammonia is heated, and gaseous ammonia is generated.

[0042] The steam line 222b is provided with the fifth flow rate control valve 318. The fifth flow rate control valve 318 controls a flow rate (that is, a supply amount) of steam to be supplied to the vaporizer 160 through the steam line 222b. In one embodiment, with an opening degree of the fifth flow rate control valve 318 being adjusted, the supply amount of steam to be supplied to the vaporizer 160 through the steam line 222b is adjusted.

[0043] The supply line 224 is connected to a downstream side of the heat recovery steam generator 170 and an upstream side of the fifth flow rate control valve 318 in the steam line 222b. The supply line 224 connects the steam line 222b and a utilization destination (not shown) at which steam is used in the combustion system 100 to each other. The supply line 224 is provided with the sixth flow rate control valve 320. The sixth flow rate control valve 320 controls a flow rate (that is, a supply amount) of steam to be supplied to the utilization destination (not shown) through the supply line 224. In one embodiment, with an opening degree of the sixth flow rate control valve 320 being adjusted, the supply amount of steam to be supplied to the utilization destination (not shown) through the supply line 224 is adjusted.

[0044] The exhaust tower 180 is provided on a downstream side of the heat recovery steam generator 170 in the exhaust line 212. The exhaust gas discharged from the combustor 120 passes through the turbine 114 and the heat recovery steam generator 170, is sent to the exhaust tower 180, and is discharged from the exhaust tower 180.

[0045] The first gas analyzer 340 is provided on the downstream side of the turbine 114 and on the upstream side of the heat recovery steam generator 170 in the exhaust line 212. The first gas analyzer 340 measures a concentration of each component in the gas in the exhaust line 212 (in one embodiment, at an installation location of the first gas analyzer 340). For example, the first gas analyzer 340 measures a concentration of a nitrogen oxide (hereinafter referred to as "NOx") and a concentration of ammonia in the exhaust line 212. Ammonia detected by the first gas analyzer 340 is unburned ammonia discharged to the exhaust line 212 without being burned in the combustor 120.

[0046] The second gas analyzer 342 is provided inside the exhaust tower 180 or on the downstream side of the exhaust tower 180 in the exhaust line 212. The second gas analyzer 342 measures a concentration of each component in the gas in the exhaust line 212 (in one embodiment, at an installation location of the second gas analyzer 342). For example, the second gas analyzer 342 measures a concentration of NOx and a concentration of ammonia in the exhaust line 212. Ammonia detected by the second gas analyzer 342 is unburned ammonia discharged to the exhaust line 212 without being burned in the combustor 120.

[0047] The first thermometer 344 is placed inside the combustor 120. The first thermometer 344 measures a temperature of gas in the combustor 120 (in one embodiment, at an installation location of the first thermometer 344).

[0048] The second thermometer 346 is placed inside the turbine 114. The second thermometer 346 measures a temperature of gas in the turbine 114 (in one embodiment, at an installation location of the second thermometer 346).

[0049] The control device 400 includes, for example, a processor 402 and a memory 404. The processor 402 includes, for example, a central processing unit (CPU). The memory 404 includes, for example, a ROM having a program or the like stored therein, and a RAM serving as a work area. The function of the control device 400 is implemented by, for example, the processor 402 executing the program stored in the memory 404.

[0050] The control device 400 controls each device included in the combustion system 100. For example, the control device 400 can control supply of ammonia and stop of the supply of ammonia by opening and closing the first shut-off valve 330, the second shut-off valve 332, the third shut-off valve 334, and the fourth shut-off valve 336. Further, the control device 400 can control the flow rate of each fluid by controlling the first pump 140, the second pump 150, the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, the fourth flow rate control valve 316, the fifth flow rate control valve 318, and the sixth flow rate control valve 320. Further, the control device 400 can acquire detection results from the first gas analyzer 340, the second gas analyzer 342, the first thermometer 344, and the second thermometer 346.2. Overview of Combustor

[0051] The combustor 120 includes a combustion chamber, an ignition device, one or a plurality of first burners, and one or a plurality of second burners.

[0052] The exhaust line 212 is connected to the combustion chamber. The ignition device is provided inside or outside the combustion chamber. A distal end of an ignition portion of the ignition device is placed inside the combustion chamber. The distal end of the ignition portion is a portion that generates a spark for starting combustion of ammonia. That is, the ignition device generates a spark in the combustion chamber. The ignition device includes, for example, an igniter.

[0053] The first burner injects ammonia toward the inside of the combustion chamber. An injection direction of ammonia of the first burner is, for example, a direction facing the spark generated by the ignition device. The first burner has one or a plurality of injection ports. Ammonia is injected from the injection port of the first burner. The first burner faces the combustion chamber. In one embodiment, the injection port of the first burner faces the combustion chamber. In the at least one embodiment, the first burner faces the spark generated by the ignition device. In one embodiment, the injection port of the first burner faces the spark generated by the ignition device.

[0054] In the at least one embodiment, the first burner is connected to each of the intake line 210, the first gaseous ammonia line 214, and the first liquid ammonia line 216. However, it suffices for the first burner to be connected to at least the first gaseous ammonia line 214 and the first liquid ammonia line 216.

[0055] The second burner injects ammonia toward the inside of the combustion chamber. An injection direction of the second burner is, for example, different from the injection direction of the first burner. The injection direction of the second burner may intersect with the injection direction of the first burner. The injection direction of the second burner may be orthogonal to the injection direction of the first burner. The injection direction of the second burner may be the same as the injection direction of the first burner. That is, the injection direction of the second burner may be coaxial with an extending direction of a flame, or may intersect with the extending direction of the flame. Further, the second burner may inject ammonia toward a center of the flame, or may inject ammonia toward a location other than the center of the flame. The second burner has one or a plurality of injection ports. Ammonia is injected from the injection port of the second burner. The second burner faces the combustion chamber. In one embodiment, the injection port of the second burner faces the combustion chamber.

[0056] In the at least one embodiment, the second burner is connected to each of the intake line 210, the second gaseous ammonia line 218, and the second liquid ammonia line 220. However, it suffices for the second burner to be connected to at least the second gaseous ammonia line 218 and the second liquid ammonia line 220.

[0057] Further, in the at least one embodiment, an amount of air injected from the first burner is smaller than an amount of air injected from the second burner. For example, in the at least one embodiment, an opening area of an injection port for air in the first burner is smaller than an opening area of an injection port for air in the second burner.

[0058] Further, in the at least one embodiment, a flow rate of ammonia injected from the first burner is larger than a flow rate of ammonia injected from the second burner. For example, in the at least one embodiment, an opening area of an injection port for ammonia in the first burner is larger than an opening area of an injection port for ammonia in the second burner.3. Control by Control Device

[0059] Next, each of first processing and second processing performed by the control device 400 in the at least one embodiment is described with reference to FIGS. 2-4. However, a configuration in which the control device 400 does not perform a freely-selected part of the first processing and the second processing described below may be adopted.3.1. First Processing

[0060] FIG. 2 is a flowchart for illustrating an example of a flow of the first processing performed by the control device 400 in the at least one embodiment. The processing flow illustrated in FIG. 2 is started, for example, when the control device 400 receives operation input of a start instruction given by an operator of the combustion system 100. When the processing flow illustrated in FIG. 2 is started, in Step S110, the control device 400 starts supply of ammonia to the combustor 120 and ignites the combustor 120 by operating the ignition device. For example, the control device 400 performs control such that ammonia is injected into the combustor 120 from at least the first burner at the time of ignition of the combustor 120. That is, it can be said that the first burner is a burner that injects ammonia for ignition. In Step S110, the control device 400 opens at least one of the first shut-off valve 330 or the second shut-off valve 332. Then, for example, in Step S110, the control device 400 may control the flow rate of ammonia to be supplied from the first burner by adjusting output of the first pump 140 and output of the second pump 150. Further, in Step S110, the control device 400 may control the flow rate of ammonia to be supplied from the first burner, by adjusting an opening degree of one or both of the first flow rate control valve 310 and the second flow rate control valve 312. The control device 400 may perform control such that ammonia is injected into the combustor 120 from the second burner in addition to the first burner at the time of ignition of the combustor 120.

[0061] As described above, in the at least one embodiment, the vaporizer 160 vaporizes liquid ammonia by heat of steam generated in the heat recovery steam generator 170. Immediately after the combustor 120 is started, for example, there is a case in which a temperature of steam generated in the heat recovery steam generator 170 is low, or a case in which a flow rate of steam is small. Further, when a flow rate of steam required at the utilization destination via the supply line 224 is large, the flow rate of steam supplied to the vaporizer 160 becomes smaller. In such cases, the flow rate of gaseous ammonia generated in the vaporizer 160 becomes smaller.

[0062] Accordingly, in Step S110, when preparation of the vaporizer 160 is not completed and liquid ammonia cannot be vaporized in the vaporizer 160, the control device 400 supplies liquid ammonia to the first burner. For example, the control device 400 may control the flow rate of liquid ammonia by adjusting the output of the second pump 150. Further, the control device 400 may control the flow rate of liquid ammonia by adjusting an opening degree of one or both of the second flow rate control valve 312 and the fourth flow rate control valve 316.

[0063] Thus, with liquid ammonia being supplied to the combustor 120 by the control device 400, a startup time of the combustion system 100 can be shortened.

[0064] In contrast, in Step S110, for example, when preparation of the vaporizer 160 is completed and liquid ammonia can be vaporized in the vaporizer 160, the control device 400 supplies any one or both of gaseous ammonia and liquid ammonia to the first burner. For example, the control device 400 may control the flow rate of gaseous ammonia by adjusting the output of the first pump 140. Further, the control device 400 may control the flow rate of liquid ammonia by adjusting the output of the second pump 150. The control device 400 may control the flow rate of gaseous ammonia by adjusting an opening degree of one or both of the first flow rate control valve 310 and the third flow rate control valve 314. Further, the control device 400 may control the flow rate of liquid ammonia by adjusting an opening degree of one or both of the second flow rate control valve 312 and the fourth flow rate control valve 316.

[0065] Next to Step S110, in Step S120, the control device 400 performs rotational speed control for increasing a rotational speed of the turbine 114 to a target rotational speed. The target rotational speed is a rotational speed of the turbine 114 at which a frequency of electric power output from the generator 130 can be set to a target frequency. The target frequency is, for example, a frequency of electric power flowing through the electric power system (frequency of commercial electric power supply). When performing the rotational speed control, the control device 400, for example, causes ammonia to be injected from one or both of the first burner and the second burner. At this time, the control device 400 may cause one or both of liquid ammonia and gaseous ammonia to be injected. For example, in Step S120, the control device 400 may control the flow rate of ammonia by adjusting the output of the first pump 140 and the output of the second pump 150. Further, in Step S120, the control device 400 may control the flow rate of ammonia by adjusting an opening degree of one or a plurality of flow rate control valves including at least one of the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, or the fourth flow rate control valve 316.

[0066] When the rotational speed of the turbine 114 reaches the target rotational speed, the control device 400 performs Step S130 next to Step S120. In Step S130, the control device 400 performs output control for varying the output (electric power generation amount) of the generator 130. For example, in Step S130, the control device 400 may control flow rate distribution of gaseous ammonia and liquid ammonia by adjusting the output of one or both of the first pump 140 and the second pump 150. Further, for example, in Step S130, the control device 400 may control the flow rate distribution of gaseous ammonia and liquid ammonia by adjusting an opening degree of one or a plurality of flow rate control valves including at least one of the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, or the fourth flow rate control valve 316. In Step S130, the control device 400 increases the output of the generator 130 by increasing the flow rate of ammonia to be supplied to the combustor 120. Further, the control device 400 decreases the output of the generator 130 by decreasing the flow rate of ammonia to be supplied to the combustor 120.

[0067] FIG. 3 is a flowchart for illustrating an example of a flow of Step S130 performed by the control device 400 in the at least one embodiment. The processing flow illustrated in FIG. 3 is repeated, for example, at time intervals set in advance while the output control is being performed. As illustrated in FIG. 3, in Step S130-1, the control device 400 determines whether or not single-fuel combustion of liquid ammonia is being performed in the combustor 120. That is, the control device 400 determines whether or not gaseous ammonia is not supplied to the combustor 120 and liquid ammonia is supplied thereto. When gaseous ammonia is not supplied to the combustor 120 and liquid ammonia is supplied thereto, the control device 400 determines that single-fuel combustion of liquid ammonia is being performed. As a result, when it is determined that single-fuel combustion of liquid ammonia is being performed (YES in Step S130-1), the control device 400 shifts the process to Step S130-3. In contrast, when it is determined that single-fuel combustion of liquid ammonia is not being performed (NO in Step S130-1), the control device 400 shifts the process to Step S130-7.

[0068] In Step S130-3, the control device 400 determines stability of supply of liquid ammonia from at least one of the first liquid ammonia line 216 or the second liquid ammonia line 220 to the combustor 120. In the at least one embodiment, the control device 400 determines whether or not an operation of the second pump 150 is stable. For example, the control device 400 determines whether or not an outlet pressure of liquid ammonia in the second pump 150 is equal to or higher than a first target pressure. When the outlet pressure of liquid ammonia in the second pump 150 is equal to or higher than the first target pressure, the control device 400 determines that the operation of the second pump 150 is stable. As a result, when it is determined that the supply of liquid ammonia to the combustor 120 is stable (YES in Step S130-3), the control device 400 shifts the process to Step S130-1. In contrast, when it is determined that the supply of liquid ammonia to the combustor 120 is not stable (NO in Step S130-3), the control device 400 shifts the process to Step S130-5.

[0069] In Step S130-5, the control device 400 increases a ratio of gaseous ammonia and decreases a ratio of liquid ammonia with respect to a flow rate of total ammonia to be supplied to the combustor 120. At this time, the control device 400 decreases the ratio of liquid ammonia to such an extent that the supply of liquid ammonia to the combustor 120 becomes stable. In other words, the control device 400 controls the flow rate of gaseous ammonia preferentially over the flow rate of liquid ammonia. For example, in Step S130-5, the control device 400 may decrease the output of the second pump 150 and increase the output of the first pump 140. For example, in Step S130-5, the control device 400 may control opening degree adjustment of the second flow rate control valve 312 and the fourth flow rate control valve 316 subordinately to opening degree adjustment of the first flow rate control valve 310 and the third flow rate control valve 314. With Step S130-5 being performed, gas-liquid mixed combustion of ammonia or single-fuel combustion of gaseous ammonia is performed. Then, the control device 400 shifts the process to Step S130-1.

[0070] In Step S130-7, the control device 400 determines whether or not single-fuel combustion of gaseous ammonia is being performed in the combustor 120. That is, the control device 400 determines whether or not liquid ammonia is not supplied to the combustor 120 and gaseous ammonia is supplied thereto. When liquid ammonia is not supplied to the combustor 120 and gaseous ammonia is supplied thereto, the control device 400 determines that single-fuel combustion of gaseous ammonia is being performed. As a result, when it is determined that single-fuel combustion of gaseous ammonia is being performed (YES in Step S130-7), the control device 400 shifts the process to Step S130-9. In contrast, when it is determined that single-fuel combustion of gaseous ammonia is not being performed (NO in Step S130-7), that is, when it is determined that gas-liquid mixed combustion of ammonia is being performed in the combustor 120, the control device 400 shifts the process to Step S130-13.

[0071] In Step S130-9, the control device 400 determines stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120. In the at least one embodiment, the control device 400 determines whether or not an operation of the vaporizer 160 is stable. For example, the control device 400 determines whether or not an outlet pressure of gaseous ammonia in the vaporizer 160 is equal to or higher than a second target pressure. When the outlet pressure of gaseous ammonia in the vaporizer 160 is equal to or higher than the second target pressure, the control device 400 determines that the operation of the vaporizer 160 is stable. As a result, when it is determined that the supply of gaseous ammonia to the combustor 120 is stable (YES in Step S130-9), the control device 400 shifts the process to Step S130-1. In contrast, when it is determined that the supply of gaseous ammonia to the combustor 120 is not stable (NO in Step S130-9), the control device 400 shifts the process to Step S130-11.

[0072] In Step S130-11, the control device 400 increases the ratio of liquid ammonia and decreases the ratio of gaseous ammonia with respect to the flow rate of total ammonia to be supplied to the combustor 120. At this time, the control device 400 decreases the ratio of gaseous ammonia to such an extent that the supply of gaseous ammonia to the combustor 120 becomes stable. In other words, the control device 400 controls the flow rate of liquid ammonia preferentially over the flow rate of gaseous ammonia. For example, in Step S130-11, the control device 400 may decrease the output of the first pump 140 and increase the output of the second pump 150. For example, in Step S130-11, the control device 400 may control opening degree adjustment of the first flow rate control valve 310 and the third flow rate control valve 314 subordinately to opening degree adjustment of the second flow rate control valve 312 and the fourth flow rate control valve 316. With Step S130-11 being performed, gas-liquid mixed combustion of ammonia or single-fuel combustion of liquid ammonia is performed. Then, the control device 400 shifts the process to Step S130-1.

[0073] In Step S130-13, the control device 400 determines stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120, and stability of supply of liquid ammonia from at least one of the first liquid ammonia line 216 or the second liquid ammonia line 220 to the combustor 120. In the at least one embodiment, the control device 400 determines whether or not operations of the first pump 140 and the second pump 150 are stable. For example, the control device 400 determines whether or not the outlet pressure of liquid ammonia in the first pump 140 is equal to or higher than the second target pressure, and the outlet pressure of liquid ammonia in the second pump 150 is equal to or higher than the first target pressure. As a result, when it is determined that the supply of gaseous ammonia and the supply of liquid ammonia to the combustor 120 are stable (YES in Step S130-13), the control device 400 shifts the process to Step S130-1. In contrast, when it is determined that the supply of gaseous ammonia or the supply of liquid ammonia to the combustor 120 is not stable (NO in Step S130-13), the control device 400 shifts the process to Step S130-15.

[0074] When it is determined in Step S130-13 that the supply of gaseous ammonia to the combustor 120 is not stable, the control device 400 performs, in Step S130-15, processing similar to Step S130-11 described above. Further, when it is determined in Step S130-13 that the supply of liquid ammonia to the combustor 120 is not stable, the control device 400 performs, in Step S130-15, processing similar to Step S130-5 described above.3.2. Second Processing

[0075] In the second processing in the at least one embodiment, the control device 400 controls the flow rate based on a concentration of NOx exhausted from the combustor 120. FIG. 4 is a flowchart for illustrating an example of a flow of the second processing performed by the control device 400 in the at least one embodiment. The processing flow illustrated in FIG. 4 is repeated, for example, at time intervals set in advance. Further, the processing flow illustrated in FIG. 4 is performed in parallel with the first processing while the first processing is being performed.

[0076] When the processing flow illustrated in FIG. 4 is started, in Step S210, the control device 400 acquires a concentration of NOx exhausted from the combustion system 100. In the at least one embodiment, the control device 400 acquires, for example, a concentration of NOx in the exhaust line 212. For example, the control device 400 acquires a concentration of NOx detected by the first gas analyzer 340 or a concentration of NOx detected by the second gas analyzer 342.

[0077] Next to Step S210, in Step S220, the control device 400 determines whether or not the acquired concentration of NOx is less than a target value. The target value of the concentration of NOx is set in advance based on the Air Pollution Control Act, ordinances of a relevant local government, or the like.

[0078] When it is determined that the acquired concentration of NOx is less than the target value (YES in Step S220), the control device 400 shifts the process to Step S230. In contrast, when it is determined that the acquired concentration of NOx is not less than the target value (NO in Step S220), that is, that the acquired concentration of NOx is equal to or greater than the target value, the control device 400 shifts the process to Step S240.

[0079] In Step S230, the control device 400 controls the flow rate of ammonia to be supplied to the combustor 120 by increasing a ratio of liquid ammonia to gaseous ammonia in total ammonia to be supplied to the combustor 120. For example, in Step S230, the control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by increasing the output of the second pump 150. In Step S230, the control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by increasing the opening degrees of the second flow rate control valve 312 and the fourth flow rate control valve 316. In Step S230, the control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by decreasing the output of the first pump 140. In Step S230, the control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by decreasing the opening degrees of the first flow rate control valve 310 and the third flow rate control valve 314. Then, the control device 400 ends the processing flow illustrated in FIG. 4.

[0080] In Step S240, the control device 400 controls the flow rate of ammonia such that at least the concentration of NOx detected by the second gas analyzer 342 becomes less than the target value. For example, in Step S240, the control device 400 may control flow rate distribution of gaseous ammonia and liquid ammonia by adjusting the output of the first pump 140 and the output of the second pump 150. In Step S240, the control device 400 may control the flow rate distribution of gaseous ammonia and liquid ammonia by adjusting an opening degree of one or a plurality of flow rate control valves including at least one of the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, or the fourth flow rate control valve 316. Then, the control device 400 ends the processing flow illustrated in FIG. 4.5. Summary

[0081] The combustion system 100 according to the at least one embodiment has been described above.

[0082] The combustion system 100 according to the at least one embodiment includes: the first gaseous ammonia line 214 which is connected to the combustor 120, and through which gaseous ammonia flows; the first liquid ammonia line 216 which is connected to the combustor 120, and through which liquid ammonia flows; the second gaseous ammonia line 218 which is connected to the combustor 120, and through which gaseous ammonia flows; the second liquid ammonia line 220 which is connected to the combustor 120, and through which liquid ammonia flows; and the control device 400 that controls a flow rate of ammonia flowing through each of the first gaseous ammonia line 214, the first liquid ammonia line 216, the second gaseous ammonia line 218, and the second liquid ammonia line 220.

[0083] Thus, the combustion system 100 according to the at least one embodiment can supply gaseous ammonia, liquid ammonia, or gaseous and liquid ammonia to the combustor 120. Further, the combustion system 100 according to the at least one embodiment can switch an ammonia supply line to the combustor 120 to one or a plurality of lines including at least one of the first gaseous ammonia line 214, the first liquid ammonia line 216, the second gaseous ammonia line 218, or the second liquid ammonia line 220, which have different influences on combustion. As a result, the combustion system 100 according to the at least one embodiment can switch a supply pattern of ammonia to the combustor 120 depending on the situation. Accordingly, the combustion system 100 according to the at least one embodiment can optimize combustion in the combustor 120 depending on the situation.

[0084] The combustion system 100 according to the at least one embodiment may further include: at least one first burner provided in the combustor 120, and connected to each of the first gaseous ammonia line 214 and the first liquid ammonia line 216; and at least one second burner provided in the combustor 120, and connected to each of the second gaseous ammonia line 218 and the second liquid ammonia line 220, and the control device 400 may perform control such that the ammonia is injected into the combustor 120 from at least the first burner at the time of ignition of the combustor 120.

[0085] As a result, when performing ignition, the combustion system 100 according to the at least one embodiment can switch a burner that supplies ammonia to the combustor 120 to the first burner having suitable ignitability.

[0086] The injection direction of the ammonia of the first burner may be different from the injection direction of the ammonia of the second burner.

[0087] As a result, when performing ignition, the combustion system 100 according to the at least one embodiment can perform ignition more suitably by the first burner having suitable ignitability. Further, in the combustion system 100 according to the at least one embodiment, the injection direction of the ammonia of the second burner is different from the injection direction of the ammonia of the first burner, and hence it is possible to optimize combustion of ammonia after ignition in the combustor 120.

[0088] The combustion system 100 according to the at least one embodiment may further include the ignition device that generates a spark in the combustor 120, and the injection direction of the ammonia of the first burner may be a direction facing the spark.

[0089] As a result, when performing ignition, the combustion system 100 according to the at least one embodiment can perform ignition more suitably by the first burner having suitable ignitability.

[0090] The first burner and the second burner may inject an oxidant gas together with the ammonia, and the amount of the oxidant gas injected from the first burner may be smaller than the amount of the oxidant gas injected from the second burner.

[0091] As a result, when performing ignition, the combustion system 100 according to the at least one embodiment can perform ignition more suitably by the first burner having suitable ignitability. Further, in the combustion system 100 according to the at least one embodiment, the injection direction of the ammonia of the second burner is different from the injection direction of the ammonia of the first burner, and hence it is possible to optimize combustion of ammonia after ignition in the combustor 120.

[0092] The control device 400 may control the flow rate based on the concentration of the nitrogen oxide exhausted from the combustor 120.

[0093] As described above, a generation amount of NOx in gaseous ammonia is lower than that in liquid ammonia. Accordingly, with the control device 400 controlling the flow rate based on the concentration of NOx exhausted from the combustor 120, the control device 400 can suitably control the concentration of NOx exhausted from the combustor 120.

[0094] For example, when the concentration of NOx exhausted from the combustor 120 is equal to or greater than the target value, the control device 400 controls the flow rate of liquid ammonia and the flow rate of gaseous ammonia such that the concentration of NOx exhausted from the combustor 120 becomes less than the target value. For example, the control device 400 increases the ratio of gaseous ammonia to liquid ammonia. As a result, the control device 400 can control the concentration of NOx exhausted from the combustor 120 to be less than the target value.

[0095] For example, when the concentration of NOx exhausted from the combustor 120 is less than the target value, the control device 400 can increase the flow rate of liquid ammonia. That is, the control device 400 can decrease the flow rate of gaseous ammonia. Accordingly, the control device 400 can reduce the flow rate of steam to be supplied to the vaporizer 160. As a result, in the combustion system 100, the flow rate of steam to be supplied to the utilization destination through the supply line 224 can be increased. Accordingly, it becomes possible to improve efficiency of the combustion system 100.

[0096] The control device 400 may control the flow rate based on the stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120.

[0097] As described above, when the temperature of steam generated in the heat recovery steam generator 170 is low, or when the flow rate of steam to be supplied to the vaporizer 160 is small, the stability of supply of gaseous ammonia to the combustor 120 decreases. Accordingly, with the control device 400 controlling the flow rate of ammonia based on the stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120, the control device 400 can suitably supply ammonia to the combustor 120.

[0098] For example, when the stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120 decreases, the control device 400 prohibits supply of gaseous ammonia to the combustor 120. As a result, the control device 400 can suitably supply ammonia to the combustor 120.

[0099] For example, when the stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120 is maintained, the control device 400 permits supply of gaseous ammonia to the combustor 120. As a result, the control device 400 can suitably supply ammonia to the combustor 120.

[0100] Although the at least one embodiment has been described above with reference to the attached drawings, it goes without saying that the present disclosure is not limited to the at least one embodiment described above. It is apparent that a person skilled in the art can conceive of various alterations or modifications within the scope described in the appended claims, and it is understood that those examples also naturally belong to the technical scope of the present disclosure.

[0101] For example, in the above, the configuration of the combustion system 100 has been described with reference to FIG. 1. However, some of the components may be omitted from the combustion system 100, or components may be added thereto.

[0102] Further, in the above, description of equipment provided in association with the combustion system 100 is omitted. However, associated equipment may be added to the combustion system 100. For example, the combustion system 100 may be used as a part of a cogeneration system, or may be used as a part of a combined cycle.

[0103] Further, in the above, the example in which ammonia is supplied to the combustor 120 in the combustion system 100 has been described. However, in addition to ammonia, fuel free of a nitrogen atom (for example, natural gas or hydrogen) may be supplied to the combustor 120.

[0104] Further, in the above, the example in which the control device 400 controls the flow rate based on the stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120 has been described. However, a configuration in which the control device 400 does not control the flow rate based on the stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line 214 or the second gaseous ammonia line 218 to the combustor 120 may be adopted.

[0105] Further, the example in which, in the above-mentioned second processing, the control device 400 controls the flow rate based on the concentration of the nitrogen oxide exhausted from the combustor 120 has been described. However, a configuration in which, in the second processing, the control device 400 does not control the flow rate based on the concentration of the nitrogen oxide exhausted from the combustor 120 may be adopted. For example, in the second processing, the control device 400 may control the flow rate based on other parameters, or may control the flow rate based on the concentration of the nitrogen oxide exhausted from the combustor 120 and other parameters.

[0106] For example, the control device 400 may control the flow rate of ammonia based on a concentration of unburned ammonia exhausted from the combustor 120. In this case, the control device 400 first acquires a concentration of unburned ammonia exhausted from the combustion system 100. The control device 400 acquires, for example, a concentration of unburned ammonia in the exhaust line 212. For example, the control device 400 acquires a concentration of ammonia detected by the first gas analyzer 340 or a concentration of ammonia detected by the second gas analyzer 342.

[0107] Then, when the acquired concentration of ammonia is less than a target value, the control device 400 controls the flow rate of ammonia to be supplied to the combustor 120 by increasing the ratio of liquid ammonia to gaseous ammonia in the total ammonia to be supplied to the combustor 120. For example, the control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by increasing the output of the second pump 150. The control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by increasing the opening degrees of the second flow rate control valve 312 and the fourth flow rate control valve 316. The control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by decreasing the output of the first pump 140. The control device 400 may increase the ratio of liquid ammonia to gaseous ammonia by decreasing the opening degrees of the first flow rate control valve 310 and the third flow rate control valve 314.

[0108] Further, when the acquired concentration of ammonia is equal to or greater than the target value, the control device 400 controls the flow rate of ammonia such that at least the concentration of ammonia detected by the second gas analyzer 342 becomes less than the target value. For example, the control device 400 may control the flow rate distribution of gaseous ammonia and liquid ammonia by adjusting the output of the first pump 140 and the output of the second pump 150. The control device 400 may control the flow rate distribution of gaseous ammonia and liquid ammonia by adjusting an opening degree of one or a plurality of flow rate control valves including at least one of the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, or the fourth flow rate control valve 316.

[0109] A generation amount of unburned ammonia obtained when gaseous ammonia is supplied to the combustor 120 is smaller than a generation amount of unburned ammonia obtained when liquid ammonia is supplied to the combustor 120. Accordingly, with the control device 400 controlling the flow rate based on the concentration of ammonia exhausted from the combustor 120, the control device 400 can suitably control the concentration of ammonia exhausted from the combustor 120.

[0110] For example, when the concentration of unburned ammonia exhausted from the combustor 120 is equal to or greater than the target value, the control device 400 performs control such that the concentration of unburned ammonia exhausted from the combustor 120 becomes less than the target value. As a result, the control device 400 can control the concentration of unburned ammonia exhausted from the combustor 120 to be less than the target value.

[0111] For example, when the concentration of unburned ammonia exhausted from the combustor 120 is less than the target value, the control device 400 can increase the flow rate of liquid ammonia. That is, the control device 400 can decrease the flow rate of gaseous ammonia. Accordingly, the control device 400 can reduce the flow rate of steam to be supplied to the vaporizer 160. As a result, in the combustion system 100, the flow rate of steam to be supplied to the utilization destination through the supply line 224 can be increased. Accordingly, it becomes possible to improve efficiency of the combustion system 100.

[0112] For example, the control device 400 may control the flow rate based on a temperature distribution of the combustor 120. In this case, the control device 400 first acquires the temperature distribution of the combustor 120. Then, the control device 400 may control the flow rate of ammonia by adjusting the output of one or both of the first pump 140 and the second pump 150 such that the acquired temperature distribution of the combustor 120 falls within a range of target values. Further, the control device 400 may control the flow rate of ammonia by adjusting an opening degree of one or a plurality of flow rate control valves including at least one of the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, or the fourth flow rate control valve 316 such that the acquired temperature distribution of the combustor 120 falls within the range of the target values. As a result, the control device 400 can suitably adjust the temperature distribution of the combustor 120.

[0113] For example, the control device 400 may control the flow rate based on a temperature of exhaust gas. In this case, the control device 400 first acquires the temperature of exhaust gas flowing through the exhaust line 212. The control device 400 acquires, for example, the temperature of exhaust gas detected by the second thermometer 346. Then, the control device 400 may control the flow rate of ammonia by adjusting the output of one or both of the first pump 140 and the second pump 150 such that the acquired temperature of exhaust gas falls within a range of target values. Further, the control device 400 may control the flow rate of ammonia by adjusting an opening degree of one or a plurality of flow rate control valves including at least one of the first flow rate control valve 310, the second flow rate control valve 312, the third flow rate control valve 314, or the fourth flow rate control valve 316 such that the acquired temperature of exhaust gas falls within the range of the target values. As a result, the control device 400 can suitably control the temperature of exhaust gas.

[0114] For example, in the above, the example in which the first burner and the second burner inject air together with ammonia, and the amount of air injected from the first burner is smaller than the amount of air injected from the second burner has been described. However, the amount of air injected from the first burner may be equal to or larger than the amount of air injected from the second burner.

[0115] Further, in the above, the example in which the first burner and the second burner inject air together with ammonia has been described. However, one or both of the first burner and the second burner may inject only ammonia. Further, one or both of the first burner and the second burner may inject other fuel in addition to ammonia.

[0116] Further, in the above, the example in which the first burner is connected to each of the intake line 210, the first gaseous ammonia line 214, and the first liquid ammonia line 216 has been described. However, it suffices for the first burner to be connected to each of at least the first gaseous ammonia line 214 and the first liquid ammonia line 216. Similarly, in the above, the example in which the second burner is connected to each of the intake line 210, the second gaseous ammonia line 218, and the second liquid ammonia line 220 has been described. However, it suffices for the second burner to be connected to each of at least the second gaseous ammonia line 218 and the second liquid ammonia line 220.

[0117] Further, in the above, the example of using air as the oxidant gas has been described. However, the oxidant gas is not limited to a specific gas type as long as the oxidant gas can burn (oxidize) ammonia. For example, combustion exhaust gas or oxygen-enriched gas may be used as the oxidant gas.

[0118] Further, in the above, the example in which the injection direction of ammonia of the first burner is a direction facing the ignition device has been described. However, a configuration in which the injection direction of ammonia of the first burner is not the direction facing the ignition device may be adopted.

[0119] Further, in the above, the example in which the injection direction of ammonia of the first burner is different from the injection direction of ammonia of the second burner has been described. However, the injection direction of ammonia of the first burner may be the same as the injection direction of ammonia of the second burner.

[0120] Further, the first burner may include a plurality of burners. The plurality of burners may be separated from each other. For example, the first burner may include a burner connected to the first gaseous ammonia line 214 and a burner connected to the first liquid ammonia line 216. Similarly, the second burner may include a plurality of burners. The plurality of burners may be separated from each other. For example, the second burner may include a burner connected to the second gaseous ammonia line 218 and a burner connected to the second liquid ammonia line 220.

[0121] Further, in the above, the example in which the combustion system 100 includes the first gaseous ammonia line 214, the first liquid ammonia line 216, the second gaseous ammonia line 218, and the second liquid ammonia line 220 has been described. However, the combustion system 100 may include, in addition to those lines, one or both of one or a plurality of gaseous ammonia lines and one or a plurality of liquid ammonia lines. When the combustion system 100 includes another gaseous ammonia line other than the first gaseous ammonia line 214 and the second gaseous ammonia line 218, a flow rate of gaseous ammonia to be supplied from the another gaseous ammonia line to the combustor 120 is smaller than the flow rate of gaseous ammonia to be supplied from the first gaseous ammonia line 214 and the second gaseous ammonia line 218 to the combustor 120. Further, when the combustion system 100 includes another liquid ammonia line other than the first liquid ammonia line 216 and the second liquid ammonia line 220, a flow rate of liquid ammonia to be supplied from the another liquid ammonia line to the combustor 120 is smaller than the flow rate of liquid ammonia to be supplied from the first liquid ammonia line 216 and the second liquid ammonia line 220 to the combustor 120.

[0122] Further, the combustion system 100 may include, in addition to the first gaseous ammonia line 214, the first liquid ammonia line 216, the second gaseous ammonia line 218, and the second liquid ammonia line 220, a line for supplying hydrocarbon-based fuel or hydrogen fuel to the combustor 120.

[0123] Further, in the above, the example in which the control device 400 performs the first processing and the second processing has been described. However, a configuration in which the control device 400 does not perform a freely-selected part of the first processing and the second processing may be adopted. For example, in Step S110 of the first processing, when igniting the combustor 120, the control device 400 supplies liquid ammonia from the first liquid ammonia line 216. Then, after ignition of the combustor 120, in Step S120 and Step S130, the control device 400 may maintain the flow rate of liquid ammonia to be supplied from the first liquid ammonia line 216 at a predetermined value, and control the flow rate of ammonia to be supplied from any one or both of the second gaseous ammonia line 218 and the second liquid ammonia line 220. Further, in Step S230 of the second processing, for example, the control device 400 may decrease the flow rate of ammonia to be supplied from any one or both of the second gaseous ammonia line 218 and the second liquid ammonia line 220, and increase the flow rate of ammonia to be supplied from any one or both of the first gaseous ammonia line 214 and the first liquid ammonia line 216.

[0124] Further, in the above, the example in which steam generated by the heat recovery steam generator 170 is used as a heat source of heat to be sent to the vaporizer 160 has been described. However, there is no limitation on the heat source of heat to be sent to the vaporizer 160. For example, the heat source of heat to be sent to the vaporizer 160 may be feed water to be supplied to the heat recovery steam generator 170, steam generated by another boiler (for example, a once-through boiler) provided in the combustion system 100, feed water to be supplied to another boiler, steam of a plant in which the combustion system 100 is installed (process steam), seawater, industrial water, tap water, outside air, or the like. Further, the vaporizer 160 may be installed in the heat recovery steam generator 170 to allow heat to be directly exchanged between liquid ammonia and exhaust gas flowing through the heat recovery steam generator 170.

[0125] Further, an intermediate heat exchanger for allowing heat to be exchanged between a heat source and a heat medium may be further provided, and the heat medium that has been subjected to the heat exchange by the intermediate heat exchanger may be sent to the vaporizer 160. For example, when a highly corrosive heat source such as seawater is used as the heat source, and a heat medium having corrosiveness lower than that of the heat source, such as industrial water, is used as the heat medium, with the intermediate heat exchanger being provided, a range in which countermeasures against corrosion are applied can be reduced.

[0126] With the at least one embodiment of the present disclosure, for example, it is possible to contribute to Goal 7 "Ensure access to affordable, reliable, sustainable and modern energy for all" and Goal 13 "Take urgent action to combat climate change and its impacts" of the Sustainable Development Goals (SDGs).

Claims

1. A combustion system, comprising:a first gaseous ammonia line which is connected to a combustor, and through which gaseous ammonia flows;a first liquid ammonia line which is connected to the combustor, and through which liquid ammonia flows;a second gaseous ammonia line which is connected to the combustor, and through which gaseous ammonia flows;a second liquid ammonia line which is connected to the combustor, and through which liquid ammonia flows; anda control device that controls a flow rate of ammonia flowing through each of the first gaseous ammonia line, the first liquid ammonia line, the second gaseous ammonia line, and the second liquid ammonia line.

2. The combustion system according to claim 1, further comprising:at least one first burner provided in the combustor, and connected to each of the first gaseous ammonia line and the first liquid ammonia line; andat least one second burner provided in the combustor, and connected to each of the second gaseous ammonia line and the second liquid ammonia line,wherein the control device performs control such that the ammonia is injected into the combustor from at least the at least one first burner at the time of ignition of the combustor.

3. The combustion system according to claim 2, wherein an injection direction of the ammonia of the at least one first burner is different from an injection direction of the ammonia of the at least one second burner.

4. The combustion system according to claim 3, further comprising an ignition device that generates a spark in the combustor,wherein the injection direction of the ammonia of the at least one first burner is a direction facing the spark.

5. The combustion system according to claim 2,wherein the at least one first burner and the at least one second burner inject an oxidant gas together with the ammonia, andwherein an amount of the oxidant gas injected from the at least one first burner is smaller than an amount of the oxidant gas injected from the at least one second burner.

6. The combustion system according to claim 1, wherein the control device controls the flow rate based on a concentration of a nitrogen oxide exhausted from the combustor.

7. The combustion system according to claim 1, wherein the control device controls the flow rate based on a concentration of unburned ammonia exhausted from the combustor.

8. The combustion system according to claim 1, wherein the control device controls the flow rate based on a temperature distribution of the combustor.

9. The combustion system according to claim 1, wherein the control device controls the flow rate based on stability of supply of gaseous ammonia from at least one of the first gaseous ammonia line or the second gaseous ammonia line to the combustor.

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