Combustion system

Abstract

A combustion system 100 comprises: a plurality of burners facing a combustion space; at least one heat exchanger Ex1, Ex2 that is supplied with ammonia F and heats the supplied ammonia F; a first fuel conduit L11 that supplies a first portion F1 of ammonia flowing out from the at least one heat exchanger Ex1, Ex2 to at least one first burner of the plurality of burners; and a second fuel conduit L12 that supplies a second portion F2, which has a higher temperature than the first portion F1, of the ammonia flowing out from the at least one heat exchanger Ex1, Ex2 to at least one second burner of the plurality of burners.

Description

Combustion System

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-69123, filed on April 22, 2024, the contents of which are incorporated herein by reference.

[0002] A combustion system may use ammonia as fuel. For example, Patent Document 1 discloses a gas turbine plant that uses ammonia as fuel. The plant includes a gas turbine including a combustor that uses ammonia as fuel. The combustor is connected to a gaseous ammonia line and a liquid ammonia line. The gaseous ammonia line is connected to a vaporizer and supplies gaseous ammonia from the vaporizer to the combustor. The vaporizer heats liquid ammonia from an ammonia tank with main steam from a heat recovery boiler. The liquid ammonia line supplies liquid ammonia from the ammonia tank to the combustor. Patent Document 1 also discloses a switch. The switch switches an ammonia supply state among a first state in which gaseous ammonia from the gaseous ammonia line is supplied to the combustor, a second state in which liquid ammonia from the liquid ammonia line is supplied to the combustor, and a third state in which gaseous ammonia from the gaseous ammonia line and liquid ammonia from the liquid ammonia line are supplied to the combustor.

[0003] International Publication No. 2022 / 172955

[0004] Generally, ammonia has low flammability, and therefore, when used as a fuel, combustion tends to become unstable.

[0005] An object of the present disclosure is to provide a combustion system that can stabilize combustion when ammonia is used as fuel.

[0006] A combustion system according to one aspect of the present disclosure includes a plurality of burners facing a combustion space, at least one heat exchanger that is supplied with ammonia and heats the supplied ammonia, a first fuel conduit that supplies a first portion of the ammonia flowing out of the at least one heat exchanger to at least one first burner of the plurality of burners, and a second fuel conduit that supplies a second portion of the ammonia flowing out of the at least one heat exchanger, the second portion having a higher temperature than the first portion, to at least one second burner of the plurality of burners.

[0007] The at least one heat exchanger may include a first heat exchanger supplied with ammonia and heating the supplied ammonia, and a second heat exchanger supplied with ammonia and heating the supplied ammonia, wherein the temperature of the ammonia flowing out of the second heat exchanger is higher than the temperature of the ammonia flowing out of the first heat exchanger, and the first fuel conduit may supply the ammonia flowing out of the first heat exchanger to at least one first burner of the plurality of burners, and the second fuel conduit may supply the ammonia flowing out of the second heat exchanger to at least one second burner of the plurality of burners.

[0008] The second heat exchanger may be connected in series with the first heat exchanger, and the second heat exchanger may be supplied with a portion of the ammonia exiting the first heat exchanger and further heat the portion of the ammonia exiting the first heat exchanger.

[0009] The combustion system may include a heat recovery steam generator that heats water to steam using exhaust gas from the multiple burners, and at least one heat exchanger may use the steam produced by the heat recovery steam generator as a heat medium to heat the ammonia.

[0010] The combustion system may include a heat recovery boiler that heats water to steam using exhaust gas from the multiple burners, and the first and second heat exchangers may use steam produced by the heat recovery boiler as a heat medium for heating the ammonia, and the second heat exchanger may use steam at a higher temperature than the steam used in the first heat exchanger.

[0011] The combustion system may include a steam turbine operated by steam from the heat recovery steam generator, and at least one heat exchanger may use low-temperature reheat steam used in the steam turbine and returned to the heat recovery steam generator or steam turbine extraction as a heat medium for heating the ammonia.

[0012] The combustion system may include a heat recovery steam generator that heats water into steam using exhaust gas from multiple burners, and a heat source that is independent of the heat recovery steam generator and heats a heat medium flowing through at least one heat exchanger.

[0013] The combustion system may include a gas turbine including multiple burners.

[0014] The combustion system may include a boiler including multiple burners.

[0015] The combustion system may include an industrial furnace that includes multiple burners.

[0016] According to the present disclosure, when ammonia is used as fuel, combustion can be stabilized.

[0017] Figure 1 is a schematic diagram of a combustion system according to a first embodiment. Figure 2 is a schematic diagram showing several types of combustors. Figure 3 is a schematic diagram showing a single combustion can. Figure 4 is a schematic diagram of a combustion system according to a second embodiment. Figure 5 is a schematic diagram of a combustion system according to a third embodiment. Figure 6 is a graph showing the relationship between combustion velocity and temperature for a mixture of ammonia and air.

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0019] 1 is a schematic diagram showing a combustion system 100 according to a first embodiment. In this disclosure, the combustion system 100 may also be simply referred to as a "system." In this embodiment, the system 100 is applied to a gas turbine combined cycle power plant (GTCC).

[0020] For example, the system 100 includes a tank (ammonia supply source) 1, a first heat exchanger Ex1, a second heat exchanger Ex2, a gas turbine 2, a heat recovery steam generator (HRSG) 3, a steam turbine 4, a condenser 51, and a chimney 6. The system 100 may further include other components. Also, the system 100 may not include at least one of the above components.

[0021] Tank 1 stores ammonia. For example, tank 1 stores liquid ammonia F. Tank 1 is connected to a fuel conduit L1. In another embodiment, instead of tank 1, an apparatus for producing ammonia may be used as an ammonia supply source.

[0022] A fuel pump P1 is provided in the fuel conduit L1. In this embodiment, a first heat exchanger Ex1 is provided in the fuel conduit L1 at a position downstream of the fuel pump P1. In this embodiment, the fuel pump P1 sends liquid ammonia F from the tank 1 to the first heat exchanger Ex1.

[0023] The first heat exchanger Ex1 is supplied with liquid ammonia F from the tank 1, and heats the supplied liquid ammonia F with a heat medium (details will be described later). The ammonia F1 flowing out from the first heat exchanger Ex1 is gaseous ammonia.

[0024] In this embodiment, the fuel conduit L1 branches into a first fuel conduit L11 and a second fuel conduit L12 at a position downstream of the first heat exchanger Ex1. In this embodiment, a portion of the ammonia F1 from the first heat exchanger Ex1 flows to the first fuel conduit L11, and the remainder flows to the second fuel conduit L12.

[0025] The first fuel conduit L11 is connected to the combustor 22 of the gas turbine 2. The first fuel conduit L11 supplies the ammonia F1 from the first heat exchanger Ex1 to the combustor 22.

[0026] A second heat exchanger Ex2 is provided in the second fuel conduit L12. In this embodiment, the second heat exchanger Ex2 is supplied with ammonia F1 from the first heat exchanger Ex1 and further heats the supplied ammonia F1 with a heat medium (details will be described later). Therefore, the temperature of the ammonia F2 flowing out of the second heat exchanger Ex2 is higher than the temperature of the ammonia F1 from the first heat exchanger Ex1. The ammonia F2 flowing out of the second heat exchanger Ex2 is gaseous ammonia.

[0027] The second fuel conduit L12 is connected to the combustor 22 of the gas turbine 2. The second fuel conduit L12 supplies the ammonia F2 from the second heat exchanger Ex2 to the combustor 22.

[0028] The gas turbine 2 includes a compressor 21, a combustor 22, a turbine 23, and a shaft 24 that connects the compressor 21 to the turbine 23. The gas turbine 2 may further include other components.

[0029] The compressor 21 compresses the intake air, which may be, for example, ambient air around the compressor 21. The compressed air is supplied to the combustor 22.

[0030] The combustor 22 combusts a mixed gas containing ammonia F1 from the first fuel conduit L11, ammonia F2 from the second fuel conduit L12, and air from the compressor 21.

[0031] FIG. 2 is a schematic diagram showing several types 22A, 22B, and 22C of combustors 22.

[0032] The left diagram shows a can-type combustor 22A. The combustor 22A includes a plurality of combustion cans 25. The plurality of combustion cans 25 are arranged in a circular shape. The plurality of combustion cans 25 are connected to one another by interconnectors 26 and are in fluid communication with one another via the interconnectors 26. Each combustion can 25 includes a casing 27, a liner 28, and a plurality of burners 29. A combustion space S is defined within the liner 28. In this disclosure, the combustion space means a space in which fuel is combusted. The plurality of burners 29 of each combustion can 25 face the same combustion space S and inject fuel (ammonia) into the combustion space S.

[0033] The center diagram shows an annular-type combustor 22B. The combustor 22B includes an outer casing 27a, an inner casing 27b, an outer liner 28a, an inner liner 28b, and a plurality of burners 29. An annular combustion space S is defined between the outer liner 28a and the inner liner 28b. The plurality of burners 29 face the combustion space S and inject fuel into the combustion space S.

[0034] The right figure shows a cannular-type combustor 22C. The combustor 22C includes an outer casing 27a, an inner casing 27b, and multiple combustion cans 25. The multiple combustion cans 25 are arranged in a circular shape in the annular region between the outer casing 27a and the inner casing 27b. The multiple combustion cans 25 are connected to each other by interconnectors 26 and are in fluid communication with each other via the interconnectors 26. Each combustion can 25 includes a liner 28 and multiple burners 29. A combustion space S is defined within the liner 28. The multiple burners 29 of each combustion can 25 face the same combustion space S and inject fuel into the combustion space S.

[0035] The combustor 22 may be any one of combustors 22A, 22B, and 22C. The combustor 22 is not limited to these, and may be any type of combustor having multiple burners facing the same combustion space S. For example, in this embodiment, the combustor 22 is a can-type combustor 22A.

[0036] 1 , combustion gas from the combustor 22 is supplied to the turbine 23. As the combustion gas passes through an impeller in the turbine 23, it rotates the impeller together with the shaft 24. The shaft 24 is connected to a first generator G1, and the rotational force of the shaft 24 is used to generate electricity. In other embodiments, the rotational force of the shaft 24 may be used in other devices. The rotational force of the shaft 24 is also used to compress air in the compressor 21. Exhaust gas from the turbine 23 is supplied to the HRSG 3.

[0037] The HRSG 3 heats water from a condenser 51 into steam using exhaust gas from the gas turbine 2. In this embodiment, the steam from the HRSG 3 is used to operate the steam turbine 4. The steam turbine 4 includes a high-pressure steam turbine 41, an intermediate-pressure steam turbine 42, a low-pressure steam turbine 43, and a shaft 44 that connects the high-pressure steam turbine 41 to the intermediate-pressure steam turbine 42 and the low-pressure steam turbine 43. The steam turbine 4 may further include other components. In other embodiments, the steam from the HRSG 3 may be used for other purposes. In this embodiment, the intermediate-pressure steam turbine 42 and the low-pressure steam turbine 43 are separated from each other, but in other embodiments, the intermediate-pressure steam turbine 42 and the low-pressure steam turbine 43 may be integrated.

[0038] The HRSG 3 is connected to the condenser 51 by a water supply pipe L2. A water supply pump P2 is provided in the water supply pipe L2. The water supply pump P2 sends water from the condenser 51 to the HRSG 3.

[0039] A portion of the water from the condenser 51 passes through a first economizer e1 in the HRSG 3 and is sent to the high-pressure drum 31. The water is heated while passing through the first economizer e1. The high-pressure drum 31 separates steam from the heated water. The water in the high-pressure drum 31 is heated by a first evaporator i1 in the HRSG 3 and returned to the high-pressure drum 31. The steam in the high-pressure drum 31 is heated by a first superheater x1 in the HRSG 3 and supplied to the high-pressure steam turbine 41 by a main steam pipe L31 (main steam).

[0040] As the main steam from the main steam pipe L31 passes through the impeller in the high-pressure steam turbine 41, it rotates the impeller together with the shaft 44. The shaft 44 is connected to the second generator G2, and the rotational force of the shaft 44 is used to generate electricity. In other embodiments, the rotational force of the shaft 44 may be used in other devices. Also, in other embodiments, the shaft 24 of the gas turbine 2 and the shaft 44 of the steam turbine 4 may be connected to a single generator.

[0041] The steam passing through the high-pressure steam turbine 41 passes through a low-temperature reheat steam pipe L33 and is sent to a second superheater (reheater) x2 in the HRSG (low-temperature reheat steam). The low-temperature reheat steam is heated by the second superheater (reheater) x2 and is supplied to the intermediate-pressure steam turbine 42 through a high-temperature reheat steam pipe L32 (high-temperature reheat steam).

[0042] When the high-temperature reheated steam from the high-temperature reheated steam pipe L32 passes through the impeller in the intermediate-pressure steam turbine 42, it rotates the impeller together with the shaft 44. The rotational force of the shaft 44 is used to generate electricity in the second generator G2. The steam that has passed through the intermediate-pressure steam turbine 42 is supplied to the low-pressure steam turbine 43, and the steam that has passed through the low-pressure steam turbine 43 is sent to the condenser 51.

[0043] Another portion of the water from the condenser 51 passes through a second economizer e2 in the HRSG 3 and is sent to the intermediate-pressure drum 32. The water is heated while passing through the second economizer e2. The intermediate-pressure drum 32 separates steam from the heated water. The water in the intermediate-pressure drum 32 is heated by a second evaporator i2 in the HRSG 3 and returned to the intermediate-pressure drum 32. The steam in the intermediate-pressure drum 32, together with steam from the low-temperature reheat steam pipe L33, is heated by a second superheater (reheater) x2 and supplied to the intermediate-pressure steam turbine 42 by the high-temperature reheat steam pipe L32.

[0044] The remainder of the water from the condenser 51 passes through a third economizer e3 in the HRSG 3 and is sent to the low-pressure drum 33. The water is heated while passing through the third economizer e3. The low-pressure drum 33 separates steam from the heated water. The water in the low-pressure drum 33 is heated by a third evaporator i3 in the HRSG 3 and returned to the low-pressure drum 33. The steam in the low-pressure drum 33 is heated by a third superheater x3 in the HRSG 3 and supplied to the low-pressure steam turbine 43 by a low-pressure steam pipe L34 (low-pressure steam).

[0045] The exhaust gas that has passed through the HRSG 3 is sent to a chimney 6. Other components (not shown) may be provided in the flue between the HRSG 3 and the chimney 6.

[0046] Next, the heat medium used in the first heat exchanger Ex1 and the second heat exchanger Ex2 will be described.

[0047] In this embodiment, steam generated by the HRSG 3 is used as a heat medium in the first heat exchanger Ex1 and the second heat exchanger Ex2. In this embodiment, at least one of the steam (main steam) S1 flowing through the main steam pipe L31, the steam (high-temperature reheat steam) S2 flowing through the high-temperature reheat steam pipe L32, the steam (low-temperature reheat steam) S3 flowing through the low-temperature reheat steam pipe L33, the steam S4 in the high-pressure drum 31, the steam S5 in the intermediate-pressure drum 32, and the steam turbine extraction steam S6 is used as a heat medium in the first heat exchanger Ex1 and the second heat exchanger Ex2. In this embodiment, the steam turbine extraction steam S6 is extracted from the low-pressure steam turbine 43. However, in other embodiments, it may be extracted from the high-pressure steam turbine 41 or the intermediate-pressure steam turbine 42. For example, the temperature of the steam S1 is 530°C or higher and 610°C or lower. For example, the temperature of the steam S2 is 300°C or higher and 400°C or lower. For example, the temperature of the steam S3 is 530° C. or higher and 620° C. or lower. The temperatures of the steams S1, S2, S3, S4, S5, and S6 are not limited to these.

[0048] In this embodiment, at least one of the steam S1, S2, S3, S4, S5, and S6 is supplied to the first heat exchanger Ex1.

[0049] For example, the first heat exchanger Ex1 may be fluidly connected to one of the main steam pipe L31, the high-temperature reheat steam pipe L32, the low-temperature reheat steam pipe L33, the high-pressure drum 31, the intermediate-pressure drum 32, and the steam turbine extraction pipe L35, and one of the steam S1, S2, S3, S4, S5, and S6 may be supplied to the first heat exchanger Ex1.

[0050] Alternatively, the first heat exchanger Ex1 may be fluidly connected to multiple or all of the main steam pipe L31, the high-temperature reheat steam pipe L32, the low-temperature reheat steam pipe L33, the high-pressure drum 31, the intermediate-pressure drum 32, and the steam turbine extraction pipe L35, and one, multiple, or all of the steam S1, S2, S3, S4, S5, and S6 may be selectively supplied to the first heat exchanger Ex1.

[0051] In this embodiment, at least one of the steam S1, S2, and S3 is supplied to the second heat exchanger Ex2.

[0052] For example, the second heat exchanger Ex2 may be fluidly connected to one of the main steam pipe L31, the high-temperature reheat steam pipe L32, and the low-temperature reheat steam pipe L33, and one of the steam S1, S2, and S3 may be supplied to the second heat exchanger Ex2.

[0053] Alternatively, the second heat exchanger Ex2 may be fluidly connected to multiple or all of the main steam pipe L31, the high-temperature reheat steam pipe L32, and the low-temperature reheat steam pipe L33, and the second heat exchanger Ex2 may be selectively supplied with one, multiple, or all of the steam S1, S2, and S3.

[0054] For example, the temperature of the steam supplied to the second heat exchanger Ex2 may be higher than the temperature of the steam supplied to the first heat exchanger Ex1.

[0055] Parameters (eg, temperature, flow rate, etc.) related to the steam supplied to the first heat exchanger Ex1 and the steam supplied to the second heat exchanger Ex2 may be determined as follows.

[0056] The parameters for the steam supplied to the first heat exchanger Ex1 may be determined so as to sufficiently vaporize the liquid ammonia F from the tank 1. Also, the parameters for the steam supplied to the second heat exchanger Ex2 may be determined so as to further heat the gaseous ammonia from the first heat exchanger Ex1.

[0057] For example, the temperature of ammonia F1 is equal to or higher than 80° C. and equal to or lower than 350° C. For example, the temperature of ammonia F2 is equal to or higher than 400° C. and equal to or lower than 600° C. The temperatures of ammonia F1 and ammonia F2 are not limited to these.

[0058] Ammonia is a low-calorie fuel, and its stoichiometric air-fuel ratio (ratio of air to 1 kg of fuel) is 6, which is smaller than that of other fuels such as natural gas. Therefore, the temperature of the premixed gas is greatly affected by the ammonia temperature. Preheating the ammonia gas temperature can reduce the temperature drop of the mixture.

[0059] Figure 6 is a graph showing the relationship between the burning velocity and temperature of ammonia and air mixtures (reference: High-temperature laminar flame speed measurements of ammonia / methane blends behind reflected shock waves, CNF 261 (2024) 113314, Miguel Figueroa-Labastida, Lingzhi Zheng, Jesse W. Streicher, Ronald K. Hanson). In Figure 6, the horizontal axis represents the temperature of the mixture (°C), and the vertical axis represents the burning velocity of the mixture (cm / s). As shown in Figure 6, the burning velocity of ammonia-containing mixtures decreases significantly as the temperature decreases, resulting in poor combustion stability.

[0060] Considering the above, it is preferable that the temperature of ammonia F2 is 400°C or higher, which does not lower the temperature of the air-fuel mixture. The combustion velocity of methane, the main component of natural gas, is about 40 cm / s. As shown in Figure 6, if the temperature of ammonia F2 is 400°C or higher, it is possible to obtain similar combustion stability in the combustor volume of a proven natural gas-fired gas turbine.

[0061] 3 is a schematic diagram showing a single combustion can 25. As described above, in this embodiment, the combustor 22 is a can-type combustor 22A and includes multiple combustion cans 25. As described above, each combustion can 25 includes multiple burners 29. In this embodiment, the combustion can 25 includes a burner 29a and multiple burners 29b. The burner 29a is arranged in the center of the combustion can 25. The multiple burners 29b are arranged in a circular shape around the burner 29a. The arrangement of the multiple burners 29 is not limited to this.

[0062] In this embodiment, in each combustion can 25, of the multiple burners 29, ammonia F1 is supplied from the first heat exchanger Ex1 to the peripheral burner 29b, and ammonia F2 is supplied from the second heat exchanger Ex2 to the central burner 29a. As described above, ammonia F1 and F2 are heated by the heat exchangers Ex1 and Ex2. Furthermore, the second heat exchanger Ex2 further heats the ammonia F1 from the first heat exchanger Ex1. Therefore, the temperature of ammonia F2 is higher than the temperature of ammonia F1. Therefore, the combustibility of ammonia F2 injected from the burner 29a of the multiple burners 29 is improved. Therefore, ammonia F2 can stabilize combustion in the combustor 22. In other words, the burner 29a functions as a pilot burner. In other embodiments, some or all of the plurality of burners 29b may be supplied with ammonia F2 from the second heat exchanger Ex2, and the remaining burners may be supplied with ammonia F1 from the first heat exchanger Ex1.

[0063] The system 100 described above includes a plurality of burners 29, at least one heat exchanger Ex1, Ex2 that receives ammonia F and heats the ammonia F, a first fuel conduit L11 that supplies a first portion F1 of the ammonia F1, F2 flowing out of the at least one heat exchanger Ex1, Ex2 to at least one first burner of the plurality of burners 29, for example, burner 29 b, and a second fuel conduit L12 that supplies a second portion F2 of the ammonia F1, F2 flowing out of the at least one heat exchanger Ex1, Ex2, the second portion F2 having a higher temperature than the first portion F1, to at least one second burner of the plurality of burners 29, for example, burner 29 a. With this configuration, the burner 29 a that receives the higher-temperature ammonia F2 functions as a pilot burner. Therefore, when ammonia is used as fuel, combustion can be stabilized.

[0064] Furthermore, in the system 100, at least one heat exchanger Ex1, Ex2 includes a first heat exchanger Ex1 that receives ammonia and heats the supplied ammonia, and a second heat exchanger Ex2 that receives ammonia and heats the supplied ammonia, wherein the temperature of ammonia F2 flowing out of the second heat exchanger Ex2 is higher than the temperature of ammonia F1 flowing out of the first heat exchanger Ex1, and the first fuel conduit L11 supplies the ammonia F1 flowing out of the first heat exchanger Ex1 to the burner 29b, and the second fuel conduit L12 supplies the ammonia F2 flowing out of the second heat exchanger Ex2 to the burner 29a. With this configuration, for example, it is possible to easily control the temperatures of ammonia F1 and ammonia F2.

[0065] Furthermore, in the system 100, the second heat exchanger Ex2 is connected in series with the first heat exchanger Ex1, and the second heat exchanger Ex2 is supplied with a portion of the ammonia F1 flowing out from the first heat exchanger Ex1 and further heats the supplied ammonia F1. In this case, the amount of steam used in the second heat exchanger Ex2 can be reduced. As described above, the temperature of the steam supplied to the second heat exchanger Ex2 may be higher than the temperature of the steam supplied to the first heat exchanger Ex1. In this case, the amount of higher-temperature steam supplied to the second heat exchanger Ex2 can be reduced. Therefore, a decrease in the efficiency of the steam turbine 4 can be suppressed.

[0066] The system 100 also includes a plurality of burners 29 and an HRSG 3 that heats water into steam using exhaust gas from the gas turbine 2, and at least one heat exchanger Ex1, Ex2 uses the steam generated by the HRSG 3 as a heat medium for heating the ammonia. With this configuration, there is no need to add new equipment for heating the heat medium. This makes it possible to reduce equipment costs.

[0067] In the system 100, the second heat exchanger Ex2 may use steam with a higher temperature than the steam used in the first heat exchanger Ex1. In this case, the second heat exchanger Ex2 can easily heat the ammonia.

[0068] The system 100 also includes a steam turbine 4 operated by steam from the HRSG 3, and at least one of the heat exchangers Ex1 and Ex2 may use, as a heat medium for heating ammonia, low-temperature reheat steam S3 or steam turbine extraction steam S6 that has been used in the steam turbine 4 and returned to the heat recovery steam generator 3. The low-temperature reheat steam or steam turbine extraction steam is steam that has been used in the steam turbine 4. Therefore, even when the low-temperature reheat steam or steam turbine extraction steam is used as a heat medium, the efficiency of the steam turbine 4 is less likely to decrease than when steam from the HRSG is used directly as a heat source.

[0069] The system 100 also includes a gas turbine 2 that includes a plurality of burners 29. In this case, the system 100 is applicable to the gas turbine 2.

[0070] Next, other embodiments will be described.

[0071] 4 is a schematic diagram of a combustion system 100A according to the second embodiment. The system 100A differs from the system 100 according to the first embodiment in that the system 100A includes a boiler furnace 7 and a boiler-related heat recovery unit 9 instead of the gas turbine 2 and the HRSG 3. The other configurations of the system 100A may be the same as those of the system 100.

[0072] The boiler furnace 7 defines a combustion space S. The boiler furnace 7 includes a plurality of combustors 71. Each of the plurality of combustors 71 includes a plurality of burners 72. The plurality of combustors 71 face the combustion space S. For example, the plurality of combustors 71 are arranged horizontally. For example, the plurality of combustors 71 are arranged vertically in a single stage or in multiple stages. Ammonia F1 from the first heat exchanger Ex1 is supplied to some of the first burners in each combustor 71, and ammonia F2 from the second heat exchanger Ex2 is supplied to other second burners in each combustor 71. The second burner that injects ammonia F2 from the second heat exchanger Ex2 functions as a pilot burner.

[0073] The water from the condenser 51 passes through the first feedwater heater 52, the deaerator 53, and the second feedwater heater 54, and is supplied to the heat recovery section 9 (S7).

[0074] For example, the heat recovery unit 9 may include at least one of a superheater, a reheater, and an economizer. The water S7 is heated by the heat recovery unit 9 and supplied to the high-pressure steam turbine 41 as steam (main steam) S1.

[0075] The steam S1 that has passed through the high-pressure steam turbine 41 is supplied to the heat recovery section 9 (steam (low-temperature reheat steam) S3). The steam S3 is heated by the heat recovery section 9 and supplied to the intermediate-pressure steam turbine 42 as steam (high-temperature reheat steam) S2. The steam that has passed through the intermediate-pressure steam turbine 42 and the low-pressure steam turbine 43 is supplied to a condenser 51. In this embodiment, steam S6 is extracted from the low-pressure steam turbine 43.

[0076] In this embodiment, at least one of the steam S1, S2, S3, and S6 is supplied to the first heat exchanger Ex1. For example, one of the steam S1, S2, S3, and S6 may be supplied to the first heat exchanger Ex1. Alternatively, one, a plurality, or all of the steam S1, S2, S3, and S6 may be selectively supplied to the first heat exchanger Ex1.

[0077] In this embodiment, at least one of the steam S1, S2, and S3 is supplied to the second heat exchanger Ex2. For example, one of the steam S1, S2, and S3 may be supplied to the second heat exchanger Ex2. Alternatively, one, a plurality, or all of the steam S1, S2, and S3 may be selectively supplied to the second heat exchanger Ex2.

[0078] For example, the boiler furnace 7 may be an industrial furnace such as a heating furnace or a cracking furnace.

[0079] The system 100A as described above achieves the same effects as the system 100 according to the first embodiment. Furthermore, for example, the system 100A may include a boiler furnace 7 including multiple burners. Furthermore, for example, the system 100A may include an industrial furnace including multiple burners. In this way, the system of the present disclosure is applicable to various facilities that are equipped with multiple burners that face the same combustion space S and use ammonia as fuel.

[0080] 5 is a schematic diagram of a combustion system 100B according to the third embodiment. The system 100B differs from the system 100 according to the first embodiment in that the first heat exchanger Ex1 and the second heat exchanger Ex2 do not use steam generated by the HRSG 3 as a heat medium, and the system 100B includes heat sources 8A and 8B for heating the heat medium. Other configurations of the system 100B may be the same as those of the system 100.

[0081] The first heating source 8A is in fluid communication with the first heat exchanger Ex1 and heats the heat medium flowing through the first heat exchanger Ex1. The second heating source 8B is in fluid communication with the second heat exchanger Ex2 and heats the heat medium flowing through the second heat exchanger Ex2. For example, the heating sources 8A and 8B may use energy other than energy generated by the combustion of ammonia F to heat the heat medium.

[0082] The system 100B described above, like the system 100 according to the first embodiment, can stabilize combustion when ammonia is used as fuel. The system 100B also includes a first heating source 8A that is independent of the HRSG 3 and heats the heat medium flowing through the first heat exchanger Ex1, and a second heating source 8B that is independent of the HRSG 3 and heats the heat medium flowing through the second heat exchanger Ex2. With this configuration, the steam generated by the HRSG 3 is not used as the heat medium. Therefore, it is possible to suppress a decrease in the efficiency of the equipment that uses the steam from the HRSG 3, that is, in this embodiment, the steam turbine 4.

[0083] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0084] For example, in the above embodiment, the second heat exchanger Ex2 is connected in series with the first heat exchanger Ex1, and the second heat exchanger Ex2 is supplied with a portion of the ammonia F1 flowing out from the first heat exchanger Ex1 and further heats the supplied ammonia F1. In another embodiment, the second heat exchanger Ex2 may be connected to the tank 1 in parallel with the first heat exchanger Ex1. In this case, the second heat exchanger Ex2 heats the liquid ammonia F from the tank 1.

[0085] Also, for example, in the above embodiments, the systems 100, 100A, and 100B include a first heat exchanger Ex1 and a second heat exchanger Ex2 that are separate from each other. In other embodiments, the systems may include a single heat exchanger. In this case, for example, gaseous ammonia F1 flowing out from the middle of the single heat exchanger may be supplied to the first fuel conduit L11, and higher-temperature gaseous ammonia F2 flowing out from the outlet of the single heat exchanger may be supplied to the second fuel conduit L12. Also, the number of heat exchangers is not limited to one or two, and may be two or more.

[0086] The present disclosure provides ２ It can promote the use of ammonia, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7 "Ensure access to affordable, reliable, sustainable and modern energy" and SDG 13 "Take urgent action to combat climate change and its impacts".

[0087] 2 Gas turbine 3 Heat recovery steam generator (HRSG) 4 Steam turbine 7 Boiler furnace (industrial furnace) 9 Heat recovery section of boiler 29 Burner 71 Combustor 72 Burner 8A First heating source 8B Second heating source 100 Combustion system 100 System 100A Combustion system 100B Combustion system Ex1 First heat exchanger Ex2 Second heat exchanger F Ammonia F1 Ammonia F2 Ammonia L11 First fuel conduit L12 Second fuel conduit S Combustion space S1 Steam S2 Steam S3 Steam S4 Steam S5 Steam S6 Steam

Claims

1. A combustion system comprising: a plurality of burners facing a combustion space; at least one heat exchanger that is supplied with ammonia and heats the supplied ammonia; a first fuel conduit that supplies a first portion of the ammonia flowing out of the at least one heat exchanger to at least one first burner of the plurality of burners; and a second fuel conduit that supplies a second portion of the ammonia flowing out of the at least one heat exchanger, the second portion having a higher temperature than the first portion, to at least one second burner of the plurality of burners.

2. The combustion system according to claim 1, wherein the at least one heat exchanger includes: a first heat exchanger supplied with ammonia and heating the supplied ammonia; and a second heat exchanger supplied with ammonia and heating the supplied ammonia, wherein the temperature of the ammonia flowing out of the second heat exchanger is higher than the temperature of the ammonia flowing out of the first heat exchanger; the first fuel conduit supplies the ammonia flowing out of the first heat exchanger to the at least one first burner of the plurality of burners; and the second fuel conduit supplies the ammonia flowing out of the second heat exchanger to the at least one second burner of the plurality of burners.

3. The combustion system according to claim 2, wherein the second heat exchanger is connected in series with the first heat exchanger, and the second heat exchanger is supplied with a portion of the ammonia flowing out of the first heat exchanger and further heats the portion of the ammonia flowing out of the first heat exchanger.

4. The combustion system according to claim 1, wherein the combustion system includes a heat recovery boiler that heats water into steam using exhaust gas from the plurality of burners, and the at least one heat exchanger uses the steam generated by the heat recovery boiler as a heat medium for heating ammonia.

5. The combustion system according to claim 2, wherein the combustion system includes a heat recovery boiler that heats water into steam using exhaust gas from the plurality of burners, the first heat exchanger and the second heat exchanger use steam generated by the heat recovery boiler as a heat medium for heating ammonia, and the second heat exchanger uses steam that has a higher temperature than the steam used in the first heat exchanger.

6. The combustion system according to claim 4, wherein the combustion system includes a steam turbine operated by steam from the heat recovery boiler, and the at least one heat exchanger uses low-temperature reheat steam used in the steam turbine and returned to the heat recovery boiler or steam turbine extraction steam as a heat medium for heating ammonia.

7. The combustion system according to claim 1, comprising: a heat recovery boiler that heats water into steam using exhaust gas from the plurality of burners; and a heat source that is independent of the heat recovery boiler and heats a heat medium flowing through the at least one heat exchanger.

8. A combustion system according to any one of claims 1 to 7, comprising a gas turbine including said plurality of burners.

9. A combustion system according to any one of claims 1 to 7, comprising a boiler including the plurality of burners.

10. A combustion system according to any one of claims 1 to 7, comprising an industrial furnace including the plurality of burners.

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