Gas turbine system

Abstract

To provide a gas turbine system which is excellent in durability and energy efficiency, and suppressed in a NOx discharge amount.SOLUTION: A gas turbine system comprises an ammonia decompression device 2 comprising; a membrane separation portion 3 composed of a hydrogen separation membrane 3b which can separate hydrogen from decomposition gas generated by ammonia decomposition, and a catalyst filling portion 4 filled with an ammonia decomposition catalyst C; a collection portion 6 collecting a residual ammonia from a hydrogen-separation treated gas containing nitrogen and the residual ammonia; and an ammonia recycle path L6 for supplying the residual ammonia collected by the collection portion 6 to the catalyst filling portion 4. The gas turbine system further comprises ammonia supply means 10 for supplying ammonia to the catalyst filling portion 4; a gas turbine unit 15 having a compressor 16, a combustor 17 and a gas turbine 18; and waste heat collection means 20 for collecting heat generated at the gas turbine unit 15, and heating a heat medium.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas turbine system that uses hydrogen obtained by decomposing ammonia as fuel.

Background Art

[0002] As the fuel of a gas turbine system, fossil fuels that inevitably emit carbon dioxide during combustion are used. However, in recent years, global warming caused by carbon dioxide released into the atmosphere has become a problem, and in order to address this, it has become an urgent task to suppress the release of carbon dioxide into the atmosphere. Therefore, gas turbine systems that use hydrogen, which does not emit carbon dioxide during combustion, as fuel have attracted attention.

[0003] However, hydrogen has a low energy density and is inefficient for transportation and storage compared to fossil fuels. For this reason, the development of a gas turbine system that uses ammonia as an energy carrier to transport hydrogen, extracts hydrogen by decomposing ammonia, and uses this hydrogen as fuel is underway.

[0004] For example, Patent Document 1 discloses a gas turbine plant that combines an ammonia decomposition device that thermally decomposes ammonia to generate hydrogen and a gas turbine.

[0005] In this gas turbine plant, ammonia is thermally decomposed in an ammonia decomposition device using steam heated by the heat generated in the gas turbine to generate a decomposition gas containing hydrogen, nitrogen, and residual ammonia. Then, the residual ammonia in the decomposition gas is removed by an ammonia removal device, and the gas after removing the residual ammonia is used as the fuel gas of the gas turbine. Also, the residual ammonia removed by the ammonia removal device is supplied again to the ammonia decomposition device for reuse.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Patent Application Laid-Open No. 2020-147481 Summary of the Invention Problems to be Solved by the Invention

[0007] By the way, in the gas turbine plant described in the above Patent Document 1, from the viewpoint of system efficiency, ammonia decomposition in the ammonia decomposer is carried out at a high pressure (about 3 to 5 MPa), so ammonia decomposition needs to be carried out at a high temperature (about 500 to 600 °C). In such a high temperature range, nitridation of the metal materials used in the ammonia decomposer and the like occurs due to ammonia and residual ammonia in the decomposition gas. Therefore, the above gas turbine plant has a problem that the durability is likely to decrease. In addition, since it is necessary to carry out ammonia decomposition at a high temperature, more steam is required, and there is also a problem that the energy efficiency of the system decreases.

[0008] Furthermore, in the above gas turbine plant, although residual ammonia is removed and reused, it is necessary to process the entire decomposition gas from the ammonia decomposer with an ammonia removal device. For this reason, a large-capacity ammonia removal device is required, and the energy required for recovery is also likely to increase.

[0009] In addition, there is also a limit to the removal of residual ammonia in the ammonia removal device. Therefore, the gas after removing the residual ammonia also contains about 0.03 mol% of ammonia. When this gas is supplied to the gas turbine, since the amount of NOx generated is large, measures for reducing it are required.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas turbine system having excellent durability and energy efficiency and capable of suppressing NOx emissions. Means for Solving the Problems

[0011] The characteristic configuration of the gas turbine system according to the present invention for achieving the above object is as follows: A membrane separation unit including a catalyst filling part filled with an ammonia decomposition catalyst and a hydrogen separation membrane capable of separating hydrogen from the decomposition gas generated by ammonia decomposition, and a recovery part for recovering the remaining ammonia from the hydrogen separation treated gas containing nitrogen and the remaining ammonia, and an ammonia decomposition device having an ammonia recycle path for supplying the remaining ammonia recovered by the recovery part to the catalyst filling part; Ammonia supply means for supplying ammonia to the catalyst filling part; A compressor for compressing air to generate compressed air, a combustor in which the hydrogen separated by the membrane separation unit is supplied through a hydrogen supply path and the supplied hydrogen is burned in the compressed air to generate combustion gas, and a gas turbine unit having a gas turbine driven by the combustion gas; Exhaust heat recovery means for recovering the heat generated by the gas turbine unit and heating a heat medium, and is provided with: The heat medium heated by the exhaust heat recovery means is supplied to the ammonia decomposition device 、 The nitrogen from which the residual ammonia has been recovered by the recovery unit is supplied as a cooling gas to the combustor and the gas turbine through the first nitrogen flow path. is at the point.

[0012] According to the above characteristic configuration, in the membrane separation unit, while decomposing ammonia by using the heat generated by the gas turbine unit, hydrogen can be selectively separated from the decomposition gas. That is, the membrane separation unit functions as a so-called membrane reactor, and in the membrane separation unit, the decomposition reaction of ammonia and the separation of hydrogen proceed in parallel. Therefore, compared with the case of decomposing ammonia without using a membrane reactor as in the prior art, the decomposition temperature can be lowered while maintaining a high conversion rate even under high pressure. Therefore, nitriding of the metal material used in the ammonia decomposition device and the like can be suppressed, and the durability is improved. Further, according to the above characteristic configuration, since ammonia can be decomposed at a lower temperature than in the prior art, the amount of the heat medium required for heating the ammonia decomposition device can be reduced, and the energy efficiency of the system can be improved. Further, according to the above characteristic configuration, hydrogen can be selectively separated from the cracked gas and obtained as high-purity hydrogen and a hydrogen-separation-treated gas of nitrogen and residual ammonia. Therefore, when recovering the residual ammonia, the hydrogen-separation-treated gas may be supplied to the recovery unit. Since the amount of gas to be processed is reduced, the volume of the recovery unit can be reduced, and the energy required for recovery can be reduced. In addition, since high-purity hydrogen can be supplied as fuel for the gas turbine unit, the thermal efficiency is also improved. Furthermore, since no ammonia remains in the fuel supplied to the gas turbine unit, or even if it remains, it is extremely small compared to the conventional case, the NOx emission amount can also be reduced. As described above, according to the above characteristic configuration, a gas turbine system excellent in durability and energy efficiency and capable of suppressing the NOx emission amount can be realized.

[0013] Further, according to the above characteristic configuration, the nitrogen from which the residual ammonia has been recovered by the recovery unit can be used for cooling high-temperature components such as the gas turbine and combustor of the gas turbine unit. Therefore, it is possible to operate at a high temperature without using an expensive heat-resistant material for the gas turbine and combustor, and it is possible to improve the thermal efficiency and reduce the cost.

[0014] The characteristic configuration of the gas turbine system according to the present invention for achieving the above object is a membrane separation unit including a catalyst filling unit filled with an ammonia decomposition catalyst and a hydrogen separation membrane capable of separating hydrogen from the cracked gas generated by ammonia decomposition, and a recovery unit for recovering the residual ammonia from the hydrogen-separation-treated gas containing nitrogen and residual ammonia, an ammonia decomposition device having an ammonia recycle path for supplying the residual ammonia recovered by the recovery unit to the catalyst filling unit, an ammonia supply means for supplying ammonia to the catalyst filling unit, a compressor for compressing air to generate compressed air, a combustor in which the hydrogen separated by the membrane separation unit is supplied through a hydrogen supply path and the supplied hydrogen is burned in the compressed air to generate combustion gas, and a gas turbine unit driven by the combustion gas, waste heat recovery means for recovering the heat generated by the gas turbine unit and heating a heat medium, and the heat medium heated by the waste heat recovery means is supplied to the ammonia decomposition device. A second nitrogen passage through which nitrogen from which the residual ammonia has been recovered by the recovery unit flows is connected to the hydrogen supply passage. The point is that the mixed gas of hydrogen and nitrogen can be supplied to the combustor.

[0015] According to the above characteristic configuration, in the membrane separation unit, while decomposing ammonia by using the heat generated in the gas turbine unit, hydrogen can be selectively separated from the decomposition gas. That is, the membrane separation unit functions as a so-called membrane reactor. In the membrane separation unit, the decomposition reaction of ammonia and the separation of hydrogen proceed in parallel. Therefore, compared with the case of decomposing ammonia without using a membrane reactor as in the prior art, the decomposition temperature can be lowered while maintaining a high conversion rate even under high pressure. Thus, nitridation of the metal material used in the ammonia decomposition device and the like can be suppressed, and the durability is improved. Further, according to the above characteristic configuration, since ammonia can be decomposed at a lower temperature than in the prior art, the amount of the heat medium required for heating the ammonia decomposition device can be reduced, and the energy efficiency of the system can be improved. Also, according to the above characteristic configuration, hydrogen can be selectively separated from the decomposition gas and obtained as high-purity hydrogen and a gas after hydrogen separation treatment of nitrogen and residual ammonia. Therefore, when recovering the residual ammonia, the gas after hydrogen separation treatment may be supplied to the recovery unit. Since the amount of the gas to be treated is reduced, the volume of the recovery unit can be reduced, and the energy required for recovery can be reduced. In addition, since high-purity hydrogen can be supplied as the fuel of the gas turbine unit, the thermal efficiency is also improved. Further, since ammonia does not remain in the fuel supplied to the gas turbine unit, or even if it remains, it is extremely small compared with the prior art, the NOx emission amount can be reduced. As described above, according to the above characteristic configuration, a gas turbine system excellent in durability and energy efficiency and capable of suppressing the NOx emission amount can be realized.

[0016] Further, for example, when only hydrogen is supplied as the fuel, when it becomes necessary to reduce the fuel supply amount to the gas turbine unit, if the supply amount becomes less than a certain level, backfire may occur and stable combustion may not be obtained. According to the above characteristic configuration, since a mixed gas of hydrogen and nitrogen can be supplied to the gas turbine unit, when it becomes necessary to reduce the fuel supply amount, a gas in which an optimum amount of nitrogen is mixed with hydrogen can be supplied, and stable combustion can be obtained.

[0017] A further characteristic configuration of the gas turbine system according to the present invention is that a second nitrogen flow path through which nitrogen from which the residual ammonia has been recovered in the recovery section flows is connected to the hydrogen supply path, and a mixed gas of the hydrogen and the nitrogen is configured to be supplied to the combustor.

[0018] For example, when only hydrogen is supplied as fuel, when it becomes necessary to restrict the fuel supply amount to the gas turbine unit, if the supply amount becomes less than a certain level, backfire may occur and stable combustion may not be obtained. According to the above characteristic configuration, since a mixed gas of hydrogen and nitrogen can be supplied to the gas turbine unit, when it becomes necessary to restrict the fuel supply amount, a gas in which an optimal amount of nitrogen is mixed with hydrogen can be supplied, and stable combustion can be obtained.

[0019] A further characteristic configuration of the gas turbine system according to the present invention is that it includes a control unit that adjusts the mixing ratio of the hydrogen and the nitrogen in the mixed gas according to load fluctuations.

[0020] According to the above characteristic configuration, the mixing ratio of the mixed gas can be adjusted according to the load fluctuation. That is, according to the load, the mixing ratio is adjusted so that an optimal amount of nitrogen is mixed with respect to hydrogen, and the mixed gas with the adjusted mixing ratio can be supplied as a fuel gas to the gas turbine unit. Therefore, for example, in the case of a high load where the required amount of hydrogen is large, the mixing ratio (hydrogen:nitrogen) is adjusted to 100:0, and only hydrogen is supplied as fuel to the gas turbine unit to obtain high thermal efficiency. On the other hand, when the load is not so high (low load), the occurrence of flashback can be suppressed and a stable combustion state can be obtained. That is, according to the above characteristic configuration, hydrogen and nitrogen are mixed so as to obtain an appropriate mixing ratio according to the load fluctuation, and while obtaining high thermal efficiency, a stable combustion state can always be maintained even when the load fluctuates. Thereby, for example, when the gas turbine system is used as a gas turbine combined cycle power generation system, stable power supply becomes possible.

[0021] A further characteristic configuration of the gas turbine system according to the present invention is that the ammonia supply means supplies the ammonia at a supply pressure higher than atmospheric pressure.

[0022] According to the above characteristic configuration, the permeation of hydrogen generated on the catalyst-filled part side can be promoted, and ammonia decomposition can be promoted.

[0023] A further characteristic configuration of the gas turbine system according to the present invention is provided with a pressure reducing means for reducing the pressure of the hydrogen permeation side from the downstream side in the flow direction of the hydrogen so that the hydrogen permeation side in the membrane separation part is at a lower pressure than the catalyst-filled part side.

[0024] According to the above characteristic configuration, the permeation of hydrogen generated on the catalyst-filled part side and ammonia decomposition can be further promoted.

[0025] A further characteristic configuration of the gas turbine system according to the present invention is provided with a sweep gas supply means for supplying a sweep gas to the hydrogen permeation side in the membrane separation part.

[0026] According to the above characteristic configuration, the permeation of hydrogen generated on the catalyst-filled part side and the ammonia decomposition can be further promoted.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0028] Hereinafter, a gas turbine system according to an embodiment of the present invention will be described with reference to the drawings. In the following, the case where the gas turbine system is a gas turbine combined cycle power generation system (GTCC) will be described as an example.

[0029] FIG. 1 is a diagram showing a schematic configuration of a gas turbine combined cycle power generation system 1 according to an embodiment. As shown in FIG. 1, the gas turbine combined cycle power generation system 1 includes an ammonia decomposition device 2 that decomposes ammonia to generate hydrogen, an ammonia supply unit 10 (ammonia supply means) that supplies ammonia to the ammonia decomposition device 2, a gas turbine unit 15 that uses hydrogen as fuel to generate combustion gas and rotates the gas turbine 18 by this combustion gas, and an exhaust heat recovery boiler unit 20 (exhaust heat recovery means) that recovers the heat generated in the gas turbine unit 15 and heats water as a heat medium. Further, the gas turbine combined cycle power generation system 1 includes a control device 25 (control unit) that controls the operation of each part, a steam turbine unit 21 in which the steam turbine 22 is rotationally driven by the steam generated in the exhaust heat recovery boiler unit 20, a first generator 19 that generates electricity using the rotational force, a second generator 23, and the like.

[0030] The ammonia decomposition device 2 is a device that decomposes ammonia to generate hydrogen, and includes a membrane separation unit 3, an ammonia recovery unit 6 (recovery unit), and an ammonia recycle path L6.

[0031] The membrane separation unit 3 is configured to function as a so-called membrane reactor, and includes a catalyst filling unit 4 filled with an ammonia decomposition catalyst C and a hydrogen separation membrane 3b capable of separating hydrogen generated by ammonia decomposition. In the present embodiment, the membrane separation unit 3 has a double tube structure including a metal tube 3a as an outer tube and a cylindrical hydrogen separation membrane 3b as an inner tube, and the ammonia decomposition catalyst C is filled between the metal tube 3a and the hydrogen separation membrane 3b to form the catalyst filling unit 4. Examples of the ammonia decomposition catalyst C include Fe-based, Co-based, Ni-based, Ru-based, and the like. Examples of the hydrogen separation membrane 3b include a silica membrane, a zeolite membrane, a palladium membrane, a carbon membrane, a MOF (metal organic framework) membrane, and the like.

[0032] The membrane separation unit 3 is configured such that steam is supplied thereto from the waste heat recovery boiler unit 20 described later through the first steam supply passage L10. The membrane separation unit 3 is heated by this steam, and the ammonia decomposition catalyst C in the catalyst filling unit 4 is heated to a predetermined temperature (for example, 300 to 450°C). Further, ammonia is supplied to the catalyst filling unit 4 of the membrane separation unit 3 at a predetermined supply pressure through an ammonia supply passage L1 having one end connected to an ammonia supply pump 12 described later.

[0033] Here, in the membrane separation unit 3, the ammonia decomposition catalyst C is heated to a predetermined temperature, and ammonia is pumped into the catalyst filling unit 4. By the action of the ammonia decomposition catalyst C, ammonia is decomposed, and a decomposition gas containing hydrogen and nitrogen is generated. Among the decomposition gases, hydrogen permeates through the cylindrical hydrogen separation membrane 3b and is selectively separated to the inside (hydrogen permeation side). That is, in the membrane separation unit 3, the decomposition of ammonia and the separation of hydrogen proceed in parallel.

[0034] Therefore, by providing the membrane separation unit 3, as described above, even under relatively high-pressure conditions where ammonia is supplied at a predetermined supply pressure, the decomposition reaction of ammonia can proceed at a temperature of about 300 to 450°C while maintaining a high conversion rate. Therefore, nitridation of the metal material used in the ammonia decomposition apparatus 2 can be suppressed, and the ammonia decomposition apparatus 2 can have high durability. In addition, since the decomposition of ammonia can be performed at a low temperature, the amount of steam supplied through the first steam supply passage L10 can be reduced, and the energy efficiency of the entire system is improved.

[0035] The high-purity hydrogen separated from the decomposed gas (e.g., 95% or more and 99.999% or less) is sent to the combustor 17 of the gas turbine unit 15 through the hydrogen supply passage L2 connected to the hydrogen permeation side of the cylindrical hydrogen separation membrane 3b. Further, the gas from which hydrogen has been separated and which contains nitrogen and unreacted ammonia (residual ammonia) (the gas after hydrogen separation treatment) is sent to the ammonia recovery section 6 through the treated gas flow passage L3 connected to the downstream side in the flow direction of ammonia in the catalyst-filled section 4. In the present embodiment, a first flowmeter S1 is provided in the hydrogen supply passage L2, and the measurement result is transmitted to the control device 25 as appropriate.

[0036] As described above, in the membrane separation section 3, since ammonia is decomposed under relatively high-pressure conditions, the energy required for boosting the pressure to supply the generated hydrogen and nitrogen to the combustor 17 to which compressed air is supplied is suppressed as compared with the case where ammonia is decomposed under low-pressure conditions.

[0037] The ammonia recovery section 6 is configured to recover residual ammonia from the gas after hydrogen separation treatment containing nitrogen and residual ammonia. Note that a known method can be used as the method for recovering residual ammonia from the gas after hydrogen separation treatment.

[0038] The ammonia recovery section 6 of the present embodiment includes an absorption section 7 that dissolves and absorbs residual ammonia in the gas after hydrogen separation treatment in water, and a separation section 8 that heats the aqueous ammonia, which is water in which ammonia has been dissolved, to separate and distill ammonia from the aqueous ammonia. As described above, in the present embodiment, since the gas processed by the ammonia recovery section 6 is the gas from which hydrogen has been separated, the volume of the ammonia recovery section 6 is smaller and the energy required for recovery is suppressed as compared with the case where a gas from which hydrogen has not been separated is processed.

[0039] Specifically, in the ammonia recovery section 6 of this embodiment, the hydrogen-separation treated gas is supplied to the absorption section 7 through the treated gas flow path L3, and the residual ammonia is dissolved in low-temperature water, thereby removing the residual ammonia from the hydrogen-separation treated gas. The nitrogen-based gas with the residual ammonia removed (for example, the residual ammonia concentration is about 0.03 mol%) is sent to the combustor 17 and the gas turbine 18 of the gas turbine unit 15 described later through the first nitrogen supply path L4 (the first nitrogen flow path), or is sent to the hydrogen supply path L2 through the second nitrogen supply path L5 (the second nitrogen flow path) described later. Note that the temperature of the nitrogen-based gas after the removal of the residual ammonia varies depending on the recovery method of the residual ammonia, but is about from room temperature to 400°C. Further, in this embodiment, depending on various conditions such as the type of the hydrogen separation membrane 3b, the supply pressure of ammonia, and the presence or absence of the sweep gas, a part of the hydrogen not separated in the membrane separation section 3 may be contained in the nitrogen-based gas after the removal of the residual ammonia.

[0040] On the other hand, the water in which the residual ammonia is dissolved is sent to the separation section 8, and in the separation section 8, it is heated by the steam supplied from the exhaust heat recovery boiler unit 20 through the second steam supply path L11. Then, ammonia is separated and distilled from the heated ammonia water using steam, and ammonia is recovered.

[0041] Note that in this embodiment, the first nitrogen supply path L4 is provided with a first flow rate adjustment valve V1 for adjusting the supply flow rate of the nitrogen-based gas to the combustor 17 and the gas turbine 18. Further, the second nitrogen supply path L5 is provided with a second flow rate adjustment valve V2 for adjusting the supply flow rate of the nitrogen-based gas to the hydrogen supply path L2, and a second flow meter S2 is provided on the downstream side in the flow direction of the nitrogen-based gas from the second flow rate adjustment valve V2. The measurement result by the second flow meter S2 is appropriately transmitted to the control device 25.

[0042] The ammonia recycling path L6 is configured to supply the residual ammonia recovered by the ammonia recovery unit 6 to the catalyst filling unit 4. Specifically, one end of the ammonia recycling path L6 of the present embodiment is connected to the separation unit 8 of the ammonia recovery unit 6, and the other end is connected between the ammonia supply pump 12 and the catalyst filling unit 4 in the ammonia supply path L1.

[0043] The ammonia supply unit 10 includes an ammonia tank 11 in which ammonia is stored, an ammonia supply pump 12 interposed in the ammonia supply path L1 connecting the ammonia tank 11 and the catalyst filling unit 4 of the membrane separation unit 3, a preheater for preheating ammonia, and the like. In the present embodiment, the ammonia tank 11 stores ammonia cooled to a temperature below the boiling point and in a state of approximately atmospheric pressure. The ammonia supply unit 10 pressurizes and preheats the ammonia in the ammonia tank 11 and supplies it to the catalyst filling unit 4 through the ammonia supply path L1 at a predetermined supply pressure (a pressure higher than atmospheric pressure, for example, about 2 to 3 MPa).

[0044] The gas turbine unit 15 has a compressor 16 (compressor), a combustor 17, and a gas turbine 18.

[0045] The compressor 16 compresses air to generate compressed air. Specifically, the compressor 16 is supplied with air through the first air supply path L7, compresses the supplied air to generate compressed air, and sends the compressed air to the combustor 17.

[0046] The combustor 17 has hydrogen separated by the membrane separation unit 3 supplied through the hydrogen supply line L2, and burns the supplied hydrogen in compressed air to generate combustion gas. Specifically, high-purity hydrogen is supplied to the combustor 17 through the hydrogen supply line L2 with one end connected to the hydrogen permeation side of the membrane separation unit 3, and a gas mainly composed of nitrogen after residual ammonia recovery is supplied to the combustor 17 through the second nitrogen supply line L5 with one end connected to the ammonia recovery unit 6 and the other end connected to the hydrogen supply line L2. Further, compressed air is supplied to the combustor 17 from the compressor 16 through the second air supply line L8. Then, the combustor 17 burns a mixture of hydrogen, a gas mainly composed of nitrogen, and compressed air, and sends the generated combustion gas to the gas turbine 18 through the combustion gas supply line L9. Thus, in this embodiment, since high-purity hydrogen is supplied to the combustor 17, the thermal efficiency is also improved, and ammonia does not remain in the supplied fuel, or even if it remains, it is extremely small, so the NOx emission amount can also be suppressed.

[0047] The gas turbine 18 is driven by the combustion gas. Specifically, the gas turbine 18 is rotationally driven by the combustion gas sent from the combustor 17, and the rotational force is transmitted to the compressor 16 and the first generator 19. Further, the combustion gas used for the rotational drive of the gas turbine 18 is sent to the exhaust heat recovery boiler unit 20 as exhaust gas.

[0048] Further, in the present embodiment, the combustor 17 and the gas turbine 18 are configured such that a gas mainly composed of nitrogen as a cooling gas is supplied through the first nitrogen supply passage L4. Thus, in the present embodiment, since the gas mainly composed of nitrogen is used as the cooling gas to cool the combustor 17 and the gas turbine 18, they can be operated at high temperatures without using expensive heat-resistant materials, improving the thermal efficiency and reducing the cost. Note that the temperature of the gas mainly composed of nitrogen as the cooling gas is about 400°C from room temperature as described above. Further, the gas mainly composed of nitrogen used for cooling the combustor 17 or the gas turbine 18 may be introduced into the combustor 17 or the gas turbine 18, or may be introduced into the exhaust heat recovery boiler unit 20, and after recovering the exhaust heat, may be exhausted.

[0049] As a mode of cooling the combustor 17 with the gas mainly composed of nitrogen, various modes can be adopted. For example, a configuration in which the gas mainly composed of nitrogen flows along the outer wall surface of the combustor 17 can be exemplified, and a mode of cooling the combustor 17 by taking heat from the outer wall surface can be exemplified. Further, as a mode of cooling the gas turbine 18, various modes can be adopted. For example, a configuration in which the gas mainly composed of nitrogen flows inside the turbine blade can be exemplified, and a mode of cooling from the inside of the turbine blade can be exemplified.

[0050] The exhaust heat recovery boiler unit 20 is configured to recover the heat of the exhaust gas by vaporizing water using the heat of the exhaust gas discharged from the gas turbine unit 15 to produce steam. Specifically, in the present embodiment, the exhaust heat recovery boiler unit 20 heats and vaporizes the water in a plurality of drums (not shown) by the heat of the exhaust gas from the gas turbine 18 to produce steam. Then, this steam is sent to the membrane separation unit 3 of the ammonia decomposition device 2 through the first steam supply passage L10 and is also sent to the separation unit 8 of the ammonia recovery unit 6 through the second steam supply passage L11. Further, the produced steam is sent to the steam turbine 22 of the steam turbine unit 21 through the third steam supply passage L12.

[0051] The steam turbine unit 21 includes a steam turbine 22, a condenser, and the like. The steam turbine 22 is rotationally driven by the steam sent from the exhaust heat recovery boiler unit 20, and the rotational force is transmitted to the second generator 23.

[0052] The first generator 19 is driven by the gas turbine 18 to generate electricity, and the second generator 23 is driven by the steam turbine 22 to generate electricity.

[0053] As described above, the control device 25 controls the operations of each part. In this embodiment, the control device 25 is configured to adjust the mixing ratio of the mixed gas of hydrogen and nitrogen supplied to the combustor 17 according to the change in the required power generation amount of the gas turbine combined cycle power generation system 1 (in other words, according to the load fluctuation). Note that the required power generation amount of the gas turbine combined cycle power generation system 1 depends on, for example, the power generation amount in power generation using variable renewable energy such as solar power generation and wind power generation. When the power generation amount in power generation using variable renewable energy is small, the required power generation amount of the gas turbine combined cycle power generation system 1 increases (that is, it becomes a high load). Information regarding the load of the gas turbine combined cycle power generation system 1 may be received by the control device 25 via wired or wireless communication, or may be input to the control device 25 by a facility manager or the like.

[0054] When the required power generation amount is large (high load), it is preferable to supply only hydrogen as fuel to the gas turbine unit 15 so as to obtain high power generation efficiency (thermal efficiency). Therefore, as shown in FIG. 2, the control device 25 of this embodiment controls the operation of the second flow rate adjustment valve V2 provided in the second nitrogen supply path L5 to be in a closed state in the case of high load, and adjusts the mixing ratio of the gas supplied to the combustor 17 (gas flowing through the hydrogen supply path L2 (high-purity hydrogen): gas flowing through the second nitrogen supply path L5 (nitrogen-based gas)) to 100:0. Thereby, only the gas (high-purity hydrogen) flowing through the hydrogen supply path L2 is supplied to the combustor 17.

[0055] On the one hand, when the load is not so high and only high-purity hydrogen is supplied as fuel, if the supply amount falls below a certain level, backfire may occur and stable combustion may not be obtained. Therefore, according to the degree of the load, the necessary amount of hydrogen is supplied, and the mixing ratio of hydrogen and nitrogen supplied to the combustor 17 is adjusted so that the supply amount of the gas supplied to the combustor 17 does not cause backfire. Specifically, the control device 25 adjusts the mixing ratio so that the mixing amount of nitrogen with respect to the hydrogen supplied to the combustor 17 increases as the load decreases.

[0056] In the present embodiment, based on the measurement results of the first flowmeter S1 and the second flowmeter S2, the control device 25 adjusts the amount of the gas (high-purity hydrogen) flowing through the hydrogen supply passage L2 and the gas (mainly nitrogen gas) flowing through the second nitrogen supply passage L5 and supplied to the hydrogen supply passage L2 so that the mixing ratio of the mixed gas becomes the target value according to the load. That is, as shown in FIG. 3, the control device 25 controls the operation of the ammonia supply pump 12 and adjusts the opening degree of the second flow control valve V2 to adjust the supply amount of the mainly nitrogen gas to the hydrogen supply passage L2 in order to adjust the supply amount of high-purity hydrogen according to the change in the load, and adjusts the flow rates of the respective gases so that the necessary amount of hydrogen is supplied and the mixing ratio becomes the target value. Thereby, hydrogen and nitrogen are mixed so as to obtain an appropriate mixing ratio according to the load fluctuation, so that a high thermal efficiency can be obtained, and a stable combustion state can always be maintained even when the load fluctuates, enabling stable power supply.

[0057] In addition, as described above, a certain amount of hydrogen may be contained in the mainly nitrogen gas. Therefore, when adjusting the flow rates of the respective gases (high-purity hydrogen and mainly nitrogen gas) so that the necessary amount of hydrogen is supplied and the mixing ratio becomes the target value, if the amount of hydrogen remaining in the mainly nitrogen gas is not negligible, the flow rates of the respective gases may be adjusted in consideration of the amount of the remaining hydrogen. On the other hand, when the amount of the remaining hydrogen is extremely small, the flow rates of the respective gases may be adjusted ignoring the amount of the remaining hydrogen. The amount of the remaining hydrogen can be obtained, for example, by analyzing the components of the gas flowing through the first nitrogen supply passage L4.

[0058] Also, in the ammonia decomposition device 2, hydrogen:nitrogen is generated at a ratio of 3:1. Therefore, the control device 25 adjusts the mixing ratio of the mixed gas so that the mixing amount of the gas flowing through the second nitrogen supply passage L5 (gas mainly composed of nitrogen) with respect to the gas flowing through the hydrogen supply passage L2 (high-purity hydrogen) becomes at most one-third. Note that, as the mixing amount of the gas mainly composed of nitrogen with respect to high-purity hydrogen increases, the amount of the gas mainly composed of nitrogen available for cooling the combustor 17 and the gas turbine 18 decreases. However, for example, a part of the gas mainly composed of nitrogen generated during operation at high load is stored in a tank or the like, and when the load decreases, the gas mainly composed of nitrogen stored in the tank may be used for mixing with high-purity hydrogen or for cooling the combustor 17 and the gas turbine 18.

[0059] In the gas turbine combined cycle power generation system 1 having the above configuration, ammonia is decomposed into hydrogen and nitrogen in the membrane separation unit 3, and the generated hydrogen is selectively separated, and high-purity hydrogen is supplied to the combustor 17. In the combustor 17, a mixture of high-purity hydrogen and compressed air as fuel is burned. Then, the generated combustion gas is sent to the gas turbine 18, whereby the gas turbine 18 is rotationally driven, and the first generator 19 is driven by the rotational force to generate power.

[0060] Also, in this gas turbine combined cycle power generation system 1, the combustion gas used for rotationally driving the gas turbine 18 is sent to the exhaust heat recovery boiler unit 20 as exhaust gas, and steam is produced using the heat of the exhaust gas in the exhaust heat recovery boiler unit 20. Then, when this steam is sent to the steam turbine unit 21, the steam turbine 22 is rotationally driven, and the second generator 23 is driven by the rotational force to generate power.

[0061] Further, in this gas turbine combined cycle power generation system 1, the mixing ratio of the hydrogen-nitrogen mixed gas supplied to the combustor 17 is adjusted so that a necessary and sufficient amount of hydrogen is supplied without significantly varying the amount of gas supplied to the combustor 17 in response to fluctuations in the required power generation amount (load fluctuations).

[0062] 〔Alternative Embodiment〕 〔1〕In the above embodiment, the gas mainly composed of nitrogen from which residual ammonia has been recovered in the ammonia recovery unit 6 is used to cool the combustor 17 and the gas turbine 18. However, the present invention is not limited to this. For example, either the combustor 17 or the gas turbine 18 may be cooled with a gas mainly composed of nitrogen, or neither the combustor 17 nor the gas turbine 18 may be cooled with a gas mainly composed of nitrogen.

[0063] 〔2〕In the above embodiment, nitrogen is mixed with the hydrogen supplied to the combustor 17. However, the present invention is not limited to this, and only hydrogen may be supplied to the combustor 17.

[0064] 〔3〕In the above embodiment, the mixing ratio of hydrogen and nitrogen in the mixed gas is adjusted in response to load fluctuations. However, the present invention is not limited to this, and the mixing ratio may not be adjusted.

[0065] 〔4〕In the above embodiment, the ammonia supply unit 10 supplies ammonia at a supply pressure higher than atmospheric pressure. However, the present invention is not limited to this, and any mode may be adopted as long as a differential pressure is generated between the catalyst filling unit 4 and the hydrogen permeation side. For example, as shown in FIG. 4, a vacuum pump 30 (pressure reducing means) for reducing the pressure of the hydrogen permeation side of the membrane separation unit 3 may be provided on the downstream side in the hydrogen flow direction in the hydrogen supply passage L2, and the hydrogen permeation side may be reduced in pressure by the vacuum pump 30 so that the hydrogen permeation side becomes lower in pressure than the catalyst filling part side. In this case, a booster 31 is provided on the downstream side of the vacuum pump 30 in the hydrogen supply passage L2 to enable hydrogen to be supplied to the combustor 17 at a predetermined supply pressure. Further, in this case, the supply pressure of ammonia to the catalyst filling part 4 may be higher than the atmospheric pressure or may be below the atmospheric pressure. Also, as shown in FIG. 5, a sweep gas supply unit 35 (sweep gas supply means) for supplying air as a sweep gas may be provided to the hydrogen permeation side of the membrane separation unit 3 through a sweep gas supply passage L13. Even in this case, the supply pressure of ammonia to the catalyst filling part 4 may be higher than the atmospheric pressure or may be below the atmospheric pressure.

[0066] 〔5〕In the above embodiment, the gas turbine system is an embodiment of a gas turbine combined cycle power generation system, but the present invention is not limited to this, and the gas turbine system according to the present invention may be adopted in a gas turbine system for power generation or a gas turbine system for an aircraft.

[0067] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction, and the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to this, and can be appropriately modified within the scope not departing from the object of the present invention.

Explanation of Reference Numerals

[0068] 1: Gas turbine combined cycle power generation system 2: Ammonia decomposition device 3: Membrane separation unit 3b: Hydrogen separation membrane 4: Catalyst filling part 6: Ammonia recovery part (recovery part) 10: Ammonia supply unit (ammonia supply means) 15: Gas turbine unit 16: Compressor 17: Combustor 18: Gas turbine 20: Exhaust heat recovery boiler unit (exhaust heat recovery means) 25: Control device (control unit) 30: Vacuum pump (pressure reducing means) 35: Sweep gas supply unit (sweep gas supply means) C: Ammonia decomposition catalyst L2: Hydrogen supply path L4: First nitrogen supply path (first nitrogen flow path) L5: Second nitrogen supply path (second nitrogen flow path) L6: Ammonia recycle path

Claims

1. An ammonia decomposition apparatus having a catalyst-filled section filled with an ammonia decomposition catalyst, a membrane separation section comprising a hydrogen separation membrane capable of separating hydrogen from decomposition gas generated by ammonia decomposition, and a recovery section for recovering the residual ammonia from the hydrogen separation-treated gas containing nitrogen and the residual ammonia, and an ammonia recycle path for supplying the residual ammonia recovered by the recovery section to the catalyst-filled section, ammonia supply means for supplying ammonia to the catalyst-filled section, a compressor for compressing air to generate compressed air, a combustor in which the hydrogen separated by the membrane separation section is supplied through a hydrogen supply path and the supplied hydrogen is burned in the compressed air to generate combustion gas, and a gas turbine unit having a gas turbine driven by the combustion gas, waste heat recovery means for recovering heat generated by the gas turbine unit and heating a heat medium, and the heat medium heated by the waste heat recovery means is supplied to the ammonia decomposition apparatus, a gas turbine system in which nitrogen from which the residual ammonia has been recovered by the recovery section is supplied as a cooling gas to the combustor and the gas turbine through a first nitrogen flow path.

2. An ammonia decomposition apparatus having a catalyst-filled section filled with an ammonia decomposition catalyst, a membrane separation section comprising a hydrogen separation membrane capable of separating hydrogen from decomposition gas generated by ammonia decomposition, and a recovery section for recovering the residual ammonia from the hydrogen separation-treated gas containing nitrogen and the residual ammonia, and an ammonia recycle path for supplying the residual ammonia recovered by the recovery section to the catalyst-filled section, ammonia supply means for supplying ammonia to the catalyst-filled section, a compressor for compressing air to generate compressed air, a combustor in which the hydrogen separated by the membrane separation section is supplied through a hydrogen supply path and the supplied hydrogen is burned in the compressed air to generate combustion gas, and a gas turbine unit having a gas turbine driven by the combustion gas, waste heat recovery means for recovering heat generated by the gas turbine unit and heating a heat medium, and the heat medium heated by the waste heat recovery means is supplied to the ammonia decomposition apparatus, a second nitrogen flow path through which nitrogen from which the residual ammonia has been recovered by the recovery section flows is connected to the hydrogen supply path, a gas turbine system configured to be able to supply a mixed gas of the hydrogen and the nitrogen to the combustor.

3. A second nitrogen flow path through which nitrogen from which the residual ammonia has been recovered by the recovery unit flows is connected to the hydrogen supply path. The gas turbine system according to claim 1, wherein the mixed gas of hydrogen and nitrogen is configured to be supplied to the combustor.

4. The gas turbine system according to claim 2 or 3, further comprising a control unit configured to adjust a mixing ratio of hydrogen and nitrogen in the mixed gas according to a load fluctuation.

5. The gas turbine system according to any one of claims 1 to 4, wherein the ammonia supply means supplies the ammonia at a supply pressure higher than atmospheric pressure.

6. The gas turbine system according to any one of claims 1 to 5, further comprising a pressure reducing means for reducing the pressure of the hydrogen permeation side from the downstream side in the flow direction of hydrogen so that the hydrogen permeation side in the membrane separation unit has a lower pressure than the catalyst filling unit side.

7. The gas turbine system according to any one of claims 1 to 6, further comprising a sweep gas supply means for supplying a sweep gas to the hydrogen permeation side in the membrane separation unit.

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