Power generation system

Abstract

This power generation system is provided with: a thermal decomposition device (10) that thermally decomposes a hydrocarbon gas into hydrogen gas and carbon; and a gas turbine (16). The fuel of the gas turbine includes a mixed gas of hydrogen and a hydrocarbon gas generated by thermal decomposition of the hydrocarbon gas by a thermal decomposition device.

Description

Technical Field

[0001] The present disclosure relates to a power generation system. Background Art

[0002] For example, Patent Document 1 listed below describes an apparatus for extracting hydrogen by thermally decomposing hydrocarbon gas such as methane via a catalyst.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-24997 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, the above-mentioned thermal decomposition does not completely decompose the hydrocarbon gas into hydrogen and carbon, but rather produces a gas mixed with hydrocarbons in a certain ratio. When hydrogen is extracted from this generated gas and used for power generation, the power generation efficiency is reduced due to the processing of hydrogen extraction.

[0008] Means for solving problems

[0009] In one embodiment of the present disclosure, a power generation system is provided. The power generation system includes a thermal decomposition device and a gas turbine. The thermal decomposition device is a device that thermally decomposes hydrocarbon gas into hydrogen and carbon. The fuel for the gas turbine includes a mixture of hydrocarbon gas and hydrogen generated by thermal decomposition of the hydrocarbon gas by the thermal decomposition device. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a block diagram showing the power generation system according to the first embodiment.

[0011] Figure 2 1 is a block diagram showing a power generation system according to a comparative example of this embodiment.

[0012] Figure 3 This is a block diagram showing a power generation system according to a second embodiment.

[0013] Figure 4 This is a block diagram showing a power generation system according to a third embodiment.

[0014] Figure 5 It is a block diagram showing a power generation system according to a fourth embodiment.

[0015] Figure 6 This is a block diagram showing a power generation system according to a fifth embodiment.

[0016] Figure 7 It is a block diagram showing a power generation system according to a sixth embodiment.

[0017] Figure 8 It is a block diagram showing a power generation system according to a seventh embodiment. DETAILED DESCRIPTION

[0018] <First embodiment>

[0019] Hereinafter, a first embodiment will be described with reference to the drawings.

[0020] Figure 1 A power generation system according to this embodiment is shown.

[0021] Figure 1 The illustrated thermal decomposition device 10 thermally decomposes methane into hydrogen and carbon via a catalyst. The catalyst is, for example, iron. A heater 12 supplies heat to the thermal decomposition device 10. Specifically, the heater 12 supplies heat to the methane and catalyst reacting in the thermal decomposition device 10. This heat supply increases the temperature of the methane and catalyst reacting in the thermal decomposition device 10 to, for example, 600 to 900°C. The heater 12 supplies heat generated by burning methane to the thermal decomposition device 10.

[0022] The methane supplied to the thermal decomposition device 10 is methane heated by the product gas heat exchanger 14 .

[0023] The product gas heat exchanger 14 utilizes the heat of the hydrogen and methane flowing out of the thermal decomposition device 10 to heat the methane supplied to the thermal decomposition device 10. The temperature T2 of the methane before heating by the product gas heat exchanger 14 is raised to a temperature T3 by the heating by the product gas heat exchanger 14. Here, the temperature T2 can be, for example, 100 to 400°C. Alternatively, the temperature T3 can be, for example, 500 to 800°C.

[0024] The methane and hydrogen mixed gas flowing out of the thermal decomposition device 10 absorbs heat in the generated gas heat exchanger 14. Therefore, the temperature T5 of the mixed gas flowing out of the generated gas heat exchanger 14 is lower than the temperature T4 of the mixed gas supplied to the generated gas heat exchanger 14. As an example, the temperature T4 can be 600 to 900°C. As an example, the temperature T5 can be 200 to 500°C.

[0025] The mixed gas flowing out of the produced gas heat exchanger 14 is used as fuel for generating electricity by the gas turbine 16 .

[0026] The exhaust gas heat exchanger 18 heats the methane supplied to the produced gas heat exchanger 14 using the heat of the exhaust gas Gex of the gas turbine 16. The temperature T1 of the methane supplied to the exhaust gas heat exchanger 18 is raised to the temperature T2 by the exhaust gas heat exchanger 18. The temperature T1 can be, for example, 20 to 50°C.

[0027] Note that solid carbon is generated in the thermal decomposition device 10. The carbon is removed by a known technique.

[0028] Functions and effects of this embodiment

[0029] Methane is thermally decomposed into carbon and hydrogen in the thermal decomposition device 10. This thermal decomposition reaction is in a state of thermal equilibrium. Specifically, the equilibrium state can be achieved in a state where methane, carbon, and hydrogen are mixed. Regardless of whether this equilibrium state is achieved, the thermal decomposition device 10 always contains a mixture of methane, carbon, and hydrogen. Therefore, the fuel gas extracted from the thermal decomposition device 10 is a mixture of methane and hydrogen.

[0030] The mixed gas taken out from the thermal decomposition device 10 is used as fuel for the gas turbine 16 without being separated into hydrogen and methane. Figure 2 As shown, compared with the case where hydrogen is separated from the mixed gas and used as fuel for the gas turbine 16 , the power generation efficiency can be improved.

[0031] Figure 2 A comparative example of this embodiment is shown. Figure 2 In the Figure 1 For convenience, corresponding components are marked with the same reference numerals.

[0032] Figure 2 The comparative example shown uses a purification device 20 to separate hydrogen from the mixed gas flowing out of the generated gas heat exchanger 14. The separated hydrogen serves as fuel for the gas turbine 16 and the heater 12. The purification device 20 is a PSA (Pressure Swing Adsorption). The mixed gas supplied to the PSA is at approximately room temperature. Therefore, to generate hydrogen, the temperature of the mixed gas flowing out of the thermal decomposition device 10 must be significantly lowered. This results in energy loss. Furthermore, the temperature of the hydrogen extracted by the purification device 20 is also approximately room temperature. Therefore, this results in a reduction in the amount of heat supplied to the gas turbine 16 and the heater 12.

[0033] According to the present embodiment described above, the following operations and effects can be obtained.

[0034] (1-1) The temperature of the gas supplied to the gas turbine 16 has an upper limit. Furthermore, the temperature of the mixed gas flowing out of the thermal decomposition device 10 may exceed this upper limit. Therefore, the heat of the mixed gas is used to heat the methane supplied to the thermal decomposition device 10 in the generated gas heat exchanger 14. This allows the temperature of the mixed gas to be lowered to a certain extent. Furthermore, the heat absorbed to lower the temperature of the mixed gas is supplied to the methane supplied to the thermal decomposition device 10. Thus, the temperature of the mixed gas supplied to the gas turbine 16 can be prevented from becoming excessively high, and the heat of the mixed gas flowing out of the thermal decomposition device 10 can be effectively utilized.

[0035] (1-2) The exhaust gas from the gas turbine 16 heats the methane supplied to the product gas heat exchanger 14 . This not only increases the temperature of the methane supplied to the thermal decomposition device 10 to the predetermined temperature T3 , but also reduces the amount of heat required for the product gas heat exchanger 14 .

[0036] (1-3) The fuel of the heater 12 is set to methane. Figure 2 As shown, compared with the case where hydrogen is used as the fuel, the generation efficiency of hydrogen can be improved.

[0037] <Second embodiment>

[0038] Figure 3 The power generation system of this embodiment is shown in FIG. Figure 3 In the Figure 1 For convenience, corresponding components are marked with the same reference numerals.

[0039] Figure 3 The power generation system shown includes a compressor 30 that compresses the mixed gas flowing out of the produced gas heat exchanger 14. The compressor 30 is configured to compress and pressurize the mixed gas so that the mixed gas supplied to the gas turbine 16 has an appropriate pressure.

[0040] The power generation system also includes an upstream and downstream heat exchanger 32 that heats the mixed gas on the downstream side of compressor 30 using the heat of the mixed gas on the upstream side of compressor 30. The upstream and downstream heat exchanger 32 reduces the temperature T5 of the mixed gas flowing out of the generated gas heat exchanger 14 to a temperature T8 before supplying it to compressor 30. Temperature T8 is, for example, 20 to 150°C. The mixed gas supplied to compressor 30 is compressed by compressor 30, raising its temperature to T9. Temperature T9 is, for example, 60 to 400°C.

[0041] The mixed gas compressed by the compressor 30 is heated by the upstream and downstream heat exchangers 32 and raised to a temperature T5.

[0042] According to the present embodiment described above, in addition to the effects based on the first embodiment described above, the following operations and effects can be obtained.

[0043] (2-1) The pressure within the thermal decomposition device 10 is preferably set to meet requirements such as increasing the thermal decomposition reaction rate. Meanwhile, the pressure of the fuel gas supplied to the gas turbine 16 is preferably set to meet requirements such as efficient fuel combustion. However, these two requirements are not necessarily the same. Therefore, in this embodiment, the power generation system is equipped with a compressor 30. This allows the pressure of the mixed gas supplied to the gas turbine 16 to be maintained at an appropriate pressure even when the pressure of the mixed gas flowing out of the thermal decomposition device 10 is lower than the appropriate pressure for the mixed gas supplied to the gas turbine 16.

[0044] (2-2) The temperature T8 of the mixed gas supplied to the compressor 30 is lowered relative to the temperature T5 of the mixed gas flowing out of the produced gas heat exchanger 14. This allows the mixed gas to be compressed more efficiently than when the mixed gas at temperature T5 is directly supplied to the compressor 30.

[0045] (2-3) The power generation system is equipped with upstream and downstream heat exchangers 32. Thus, heat generated when the temperature of the mixed gas is temporarily lowered when the mixed gas is supplied to the compressor 30 is applied to the mixed gas downstream of the compressor 30. Therefore, the heat absorbed from the mixed gas before being supplied to the compressor 30 can be effectively utilized.

[0046] <Third embodiment>

[0047] Figure 4 The power generation system of this embodiment is shown in FIG. Figure 4 In, with Figure 1 For convenience, corresponding components are marked with the same reference numerals.

[0048] like Figure 4 As shown, the power generation system includes a buffer tank 40. The mixed gas flowing out of the produced gas heat exchanger 14 is supplied to the buffer tank 40. The buffer tank 40 stores the mixed gas to be supplied to the gas turbine 16.

[0049] According to the present embodiment described above, in addition to the effects based on the first embodiment described above, the following operations and effects can be obtained.

[0050] (3-1) The power generation system includes the buffer tank 40. Thus, even if the required load of the gas turbine 16 fluctuates and the flow rate of the air-fuel mixture to be supplied to the gas turbine 16 fluctuates, the required amount of air-fuel mixture can be stably supplied to the gas turbine 16.

[0051] <Fourth embodiment>

[0052] Figure 5 The power generation system of this embodiment is shown in FIG. Figure 5 In the Figure 1 For convenience, corresponding components are marked with the same reference numerals.

[0053] like Figure 5 As shown, the power generation system includes a compressor 30 that compresses the mixed gas flowing out of the generated gas heat exchanger 14, and a buffer tank 40 that stores the mixed gas compressed by the compressor 30. The power generation system also includes an upstream and downstream heat exchanger 32 that uses the heat of the mixed gas on the upstream side of the compressor 30 to heat the mixed gas on the downstream side of the buffer tank 40.

[0054] According to the present embodiment described above, in addition to the effects based on the second embodiment and the third embodiment, the following operations and effects can be obtained.

[0055] (4-1) The buffer tank 40 is provided downstream of the compressor 30. This increases the amount of mixed gas stored in the buffer tank 40 compared to a case where the compressor 30 is not provided upstream of the buffer tank 40.

[0056] (4-2) The mixed gas downstream of the buffer tank 40 is heated by the upstream and downstream heat exchanger 32. This increases the amount of mixed gas stored in the buffer tank 40 compared to the case where the mixed gas between the compressor 30 and the buffer tank 40 is heated by the upstream and downstream heat exchanger 32.

[0057] <Fifth embodiment>

[0058] Figure 6 The power generation system of this embodiment is shown in FIG. Figure 6 In the Figure 1 For convenience, corresponding components are marked with the same reference numerals.

[0059] like Figure 6 As shown, the power generation system includes a bypass passage 52. The bypass passage 52 is a path for directly supplying the methane heated by the exhaust gas heat exchanger 18 to the gas turbine 16 while bypassing the thermal decomposition device 10.

[0060] Specifically, the ratio of methane flowing out of the exhaust gas heat exchanger 18 to be supplied to the produced gas heat exchanger 14 and the gas turbine 16 is controlled by the flow control valve 50. Here, the ratio of methane supplied to the gas turbine 16 via the bypass passage 52 is 0 to 100%.

[0061] According to the present embodiment described above, in addition to the effects based on the first embodiment described above, the following operations and effects can be obtained.

[0062] (5-1) The power generation system is provided with the bypass passage 52 . This makes it possible to adjust the hydrogen concentration in the air-fuel mixture supplied to the gas turbine 16 .

[0063] (5-2) The methane heated by the exhaust gas heat exchanger 18 is supplied to the bypass passage 52 . This increases the temperature of the methane supplied to the gas turbine 16 compared to the case where the methane supplied to the exhaust gas heat exchanger 18 is supplied to the bypass passage 52 .

[0064] <Sixth embodiment>

[0065] Figure 7 The power generation system of this embodiment is shown in FIG. Figure 7 In the Figure 6 For convenience, corresponding components are marked with the same reference numerals.

[0066] like Figure 7 As shown, the power generation system does not include the exhaust gas heat exchanger 18 . In addition, the power generation system includes a bypass passage 52 for supplying methane to the gas turbine 16 while bypassing the produced gas heat exchanger 14 .

[0067] Specifically, the power generation system controls the ratio of methane supplied to the produced gas heat exchanger 14 and the gas turbine 16 by the flow control valve 50. Here, the ratio of methane supplied to the gas turbine 16 via the bypass passage 52 is 0 to 100%.

[0068] According to the present embodiment described above, it is possible to achieve the effect based on the effect (1-1) of the first embodiment and the effect based on the effect (5-1) of the fifth embodiment.

[0069] <Seventh embodiment>

[0070] Figure 8 The power generation system of this embodiment is shown in FIG. Figure 8 In the Figure 7 For convenience, corresponding components are marked with the same reference numerals.

[0071] like Figure 8 As shown, the power generation system does not include the exhaust gas heat exchanger 18 . In addition, the power generation system includes a bypass passage 52 for supplying methane to the gas turbine 16 while bypassing the produced gas heat exchanger 14 .

[0072] Specifically, the power generation system controls the ratio of methane supplied to the produced gas heat exchanger 14 and the gas turbine 16 by the flow control valve 50. Here, the ratio of methane supplied to the gas turbine 16 via the bypass passage 52 is 0 to 100%.

[0073] The power generation system further includes a compressor 30 for compressing the mixed gas flowing out of the produced gas heat exchanger 14. The compressor 30 is configured to compress and pressurize the mixed gas so that the pressure of the mixed gas supplied to the gas turbine 16 becomes appropriate.

[0074] Furthermore, the power generation system includes an upstream and downstream heat exchanger 32 that heats the mixed gas on the downstream side of the compressor 30 using the heat of the mixed gas on the upstream side of the compressor 30 .

[0075] The bypass passage 52 merges upstream of the compressor 30 with the flow path of the mixed gas that has absorbed heat in the upstream and downstream heat exchangers 32 .

[0076] According to the present embodiment described above, in addition to the effects based on the effects of the second embodiment and the effects based on the effects of the seventh embodiment, the following operations and effects can be achieved.

[0077] (7-1) The bypass passage 52 is connected upstream of the compressor 30. This makes it possible to increase the pressure of methane supplied to the gas turbine 16 via the bypass passage 52 without increasing the number of compressors.

[0078] Correspondence

[0079] The correspondence between the matters in the above embodiment and the matters described in the column of "Supplementary Notes" is as follows. The correspondence is shown below by the number of each solution described in the column of "Supplementary Notes". [1, 2, 9] Hydrocarbon gas corresponds to methane. "Mixed gas as fuel for gas turbine" is in Figure 1 、 Figures 3 to 8 [3] corresponds to supplying methane as a heat source to the thermal decomposition device 10. [4, 5] corresponds to supplying a mixed gas of methane and hydrogen flowing out of the thermal decomposition device 10 to the gas turbine 16. Figure 3 、 Figure 5 as well as Figure 8 Corresponding. [6] Figure 4 as well as Figure 5 Corresponding. [7] Figures 6 to 8 Corresponding. [8] Figure 6 correspond.

[0080] <Other Implementation Methods>

[0081] It should be noted that this embodiment can be implemented by modifications as follows: This embodiment and the following modifications can be implemented in combination with each other within a range that does not technically conflict.

[0082] About the heater

[0083] Heat for thermal decomposition of methane in heater 12 does not necessarily have to be generated by combustion of methane. For example, heat for thermal decomposition of methane can be generated by burning a mixture of methane and hydrogen obtained by thermal decomposition of methane. Alternatively, heat from exhaust gas from gas turbine 16 can be utilized.

[0084] For example, when the temperature T3 of the methane heated by the produced gas heat exchanger 14 is sufficiently high, the heater 12 may not be provided.

[0085] About thermal decomposition equipment

[0086] In the above embodiment, carbon is removed from the pyrolysis device 10 separately from the mixed gas, but this is not the only option. For example, a mixture of carbon and mixed gas may be supplied to the product gas heat exchanger 14. In this case, a cyclone separator or the like may be provided downstream of the product gas heat exchanger 14 to remove the carbon.

[0087] About the produced gas heat exchanger

[0088] ·exist Figure 1 、 Figures 3 to 6 In the embodiment, the methane to be heated in the product gas heat exchanger 14 is methane at room temperature heated by exhaust gas, but the present invention is not limited thereto. For example, methane may be heated by heat obtained by combustion of methane.

[0089] ·exist Figure 1 、 Figures 3 to 6 In the embodiment, methane to be heated in the product gas heat exchanger 14 may be methane at room temperature. In other words, heating may be performed without utilizing exhaust gas or the like.

[0090] The produced gas heat exchanger 14 is not necessarily provided.

[0091] 「About upstream and downstream heat exchangers」

[0092] ·exist Figure 3 、 Figure 5 as well as Figure 8 , the upstream and downstream heat exchangers 32 are configured to heat the mixed gas downstream of the compressor 30 using only the heat of the mixed gas upstream of the compressor 30, but the present invention is not limited thereto. For example, the heat of the mixed gas of methane and hydrogen flowing out of the thermal decomposition device 10 may also be utilized.

[0093] The upstream and downstream heat exchangers 32 are not necessarily required. For example, the heat of the mixed gas upstream of the compressor 30 can be used to heat methane at room temperature, thereby heating the methane to be heated in the product gas heat exchanger 14. Alternatively, the mixed gas downstream of the compressor 30 can be heated using, for example, a mixed gas of methane and hydrogen flowing out of the thermal decomposition device 10.

[0094] The temperature of the mixed gas supplied to the upstream and downstream heat exchangers 32 and the temperature of the mixed gas supplied from the upstream and downstream heat exchangers 32 to the gas turbine 16 do not necessarily have to be the same temperature.

[0095] About the bypass line

[0096] ·exist Figure 7 as well as Figure 8 In the illustrated configuration, an exhaust gas heat exchanger 18 may be provided between the flow control valve 50 and the produced gas heat exchanger 14 .

[0097] The bypass passage 52 can also be connected to the inlet of the buffer tank 40. Figure 4 This is effective when the compressor 30 is not provided as illustrated. In this case, the methane supplied to the bypass passage 52 does not need to be heated by the exhaust gas heat exchanger 18 .

[0098] Regarding gas turbine fuel

[0099] The methane supplied to the thermal decomposition device 10 and the like is extracted from natural gas and the like, and the fuel of the gas turbine 16 may include liquefied natural gas in addition to a mixed gas of hydrogen and methane.

[0100] About Hydrocarbon Gases

[0101] The hydrocarbon gas does not necessarily have to be methane. For example, it may be propane. In this case, the substance flowing out of the thermal decomposition device contains methane, ethylene, propane, etc. in addition to hydrogen and carbon.

[0102] <Note>

[0103] 1. A power generation system comprising a thermal decomposition device and a gas turbine, wherein the thermal decomposition device is a device that thermally decomposes hydrocarbon gas into hydrogen and carbon, and the fuel for the gas turbine comprises a mixture of hydrocarbon gas and hydrogen generated by thermal decomposition of the hydrocarbon gas by the thermal decomposition device.

[0104] In the above configuration, the gas turbine fuel comprises a mixture of hydrocarbon gas and hydrogen, obtained by thermally decomposing hydrocarbon gas. Therefore, compared to extracting hydrogen from the gas mixture and selectively using it as fuel for the gas turbine, the process of extracting hydrogen from the gas mixture can be omitted. Consequently, compared to extracting hydrogen from the gas mixture and using it as fuel for the turbine, power generation efficiency can be improved.

[0105] 2. The power generation system according to item 1 above, further comprising a produced gas heat exchanger configured to impart heat of the mixed gas produced by the thermal decomposition device to the hydrocarbon gas supplied to the thermal decomposition device.

[0106] 3. The power generation system according to 1 or 2 above, wherein the thermal decomposition device is configured to utilize heat generated by combustion of the hydrocarbon gas for the thermal decomposition.

[0107] 4. The power generation system according to any one of 1 to 3 above, further comprising a compressor, wherein the compressor is configured to compress the mixed gas supplied to the gas turbine.

[0108] 5. The power generation system according to the above paragraph 4, further comprising an upstream and downstream heat exchanger, wherein the upstream and downstream heat exchanger is configured to absorb heat from the mixed gas supplied to the compressor, thereby lowering the temperature of the mixed gas supplied to the compressor, and to impart the heat absorbed from the mixed gas supplied to the compressor to the mixed gas compressed by the compressor, thereby raising the temperature of the mixed gas compressed by the compressor.

[0109] 6. The power generation system according to any one of 1 to 5 above, further comprising a buffer tank configured to store the mixed gas generated by the thermal decomposition device before the mixed gas is supplied to the gas turbine.

[0110] 7. The power generation system according to any one of 1 to 6 above, further comprising a bypass line configured to allow the hydrocarbon gas to bypass the thermal decomposition device and be supplied to the gas turbine.

[0111] 8. The power generation system according to item 7 above, wherein the bypass line is configured to be heated by heat of the exhaust gas of the gas turbine.

[0112] 9. The power generation system according to any one of 1 to 8 above, wherein the hydrocarbon gas is methane.

Claims

1. A power generation system, wherein: The power generation system comprises a thermal decomposition device and a gas turbine. The thermal decomposition device is a device that thermally decomposes hydrocarbon gas into hydrogen and carbon. The fuel of the gas turbine includes a mixed gas of hydrocarbon gas and hydrogen generated by thermally decomposing the hydrocarbon gas by the thermal decomposition device.

2. The power generation system according to claim 1, wherein: The power generation system includes a generated gas heat exchanger, The generated gas heat exchanger is configured to impart heat of the mixed gas generated by the thermal decomposition device to the hydrocarbon gas supplied to the thermal decomposition device.

3. The power generation system according to claim 1, wherein: The thermal decomposition device is configured to utilize heat generated by combustion of hydrocarbon gas for the thermal decomposition.

4. The power generation system according to claim 1, wherein: The power generation system includes a compressor, The compression mechanism is configured to compress the air-fuel mixture supplied to the gas turbine.

5. The power generation system according to claim 4, wherein The power generation system is provided with upstream and downstream heat exchangers, The upstream and downstream heat exchangers are configured to absorb heat from the mixed gas supplied to the compressor, thereby lowering the temperature of the mixed gas supplied to the compressor, and to impart the heat absorbed from the mixed gas supplied to the compressor to the mixed gas compressed by the compressor, thereby increasing the temperature of the mixed gas compressed by the compressor.

6. The power generation system according to claim 1, wherein: The power generation system includes a buffer tank, The buffer tank is configured to store the mixed gas generated by the thermal decomposition device before the mixed gas is supplied to the gas turbine.

7. The power generation system according to claim 1, wherein: The power generation system is provided with a bypass line, The bypass line is configured to allow the hydrocarbon gas to bypass the thermal decomposition device and be supplied to the gas turbine.

8. The power generation system according to claim 7, wherein: The bypass line is configured to be heated by heat of exhaust gas from the gas turbine.

9. The power generation system according to claim 1, wherein: The hydrocarbon gas is methane.

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