Steam Turbine System

Abstract

To provide a highly efficient steam turbine system that can restrain generation of carbon dioxide and nitrogen oxides.SOLUTION: A steam turbine system comprises a hydrogen supply line constituted so as to supply hydrogen, an oxygen supply line constituted so as to supply oxygen, a burner for burning the hydrogen supplied from the hydrogen supply line by using the oxygen supplied from the oxygen supply line, a steam turbine to be driven by steam discharged from the burner, and a condenser constituted so as to condense the steam discharged from the steam turbine.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to steam turbine systems. [Background technology]

[0002] Gas turbine systems, which burn gaseous fuel in pressurized air and convert the enthalpy of the exhaust gas after combustion into rotational power, are used as various power sources and generator drive sources. To improve the efficiency of gas turbine systems, cogeneration systems, in which the exhaust gas from the gas turbine system is introduced into a heat recovery boiler to generate steam and then used for heat recovery, and combined cycle systems, in which a steam turbine drives a generator to generate electricity, are widely used.

[0003] Furthermore, Patent Document 1 discloses a steam turbine set intended to enhance the peak shaving capacity of a thermal power generation unit. This steam turbine set drives a hydrogen gas turbine with steam generated by burning hydrogen in a combustor, and the steam leaving the hydrogen gas turbine is supplied to the steam replenishment port of the steam turbine and further expanded by the steam turbine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3230557 Summary of the Invention [Problem to be solved by the invention]

[0005] In existing gas turbine systems, exhaust gas from a gas turbine can only be expanded and decompressed to a pressure that allows ventilation of downstream equipment. The temperature is typically high (e.g., above 500°C). Therefore, recovering the energy contained in the exhaust gas is essential for improving efficiency. For this reason, the cogeneration systems and combined-cycle systems described above require complex equipment downstream of the gas turbine, such as a heat recovery steam generator and exhaust stack (in the case of combined-cycle systems, these are also required, such as a steam turbine and generator). Furthermore, energy losses in each component limit efficiency improvement. Furthermore, hydrocarbon gaseous fuels contain a significant amount of carbon, which generates carbon dioxide upon combustion and nitrogen oxides when nitrogen in the air is oxidized. Carbon dioxide is a global warming substance, and nitrogen oxides are a pollution-causing substance, so it is desirable to minimize these emissions. Furthermore, even the steam turbine set described in Patent Document 1 has limitations on efficiency improvement.

[0006] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a highly efficient steam turbine system that can suppress the generation of carbon dioxide and nitrogen oxides. [Means for solving the problem]

[0007] In order to achieve the above object, a steam turbine system according to at least one embodiment of the present disclosure includes: a hydrogen supply line configured to supply hydrogen; an oxygen supply line configured to supply oxygen; a combustor configured to combust the hydrogen supplied from the hydrogen supply line using the oxygen supplied from the oxygen supply line; a steam turbine driven by the steam discharged from the combustor; a condenser configured to condense water vapor discharged from the steam turbine; Equipped with. [Effects of the Invention]

[0008] At least one embodiment of the present disclosure provides a highly efficient steam turbine system that can suppress the generation of carbon dioxide and nitrogen oxides. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a steam turbine system 2 according to an embodiment. [Figure 2] FIG. 10 is a schematic configuration diagram of a steam turbine system 2 (2B) according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention.

[0011] For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.

[0012] For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.

[0013] For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained.

[0014] On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0015] FIG. 1 is a schematic configuration diagram of a steam turbine system 2 (2A) according to one embodiment. As shown in FIG. 1 , the steam turbine system 2 includes an oxygen concentrator 4, an oxygen supply line 6, a hydrogen supply line 8, a combustor 10, a compressor 12, a steam turbine 18, a generator 20, an extraction steam circulation line 22, a start-up air line 24, a condenser 26, an exhaust return line 30, and a vacuum device 28.

[0016] The oxygen concentrator 4 takes in air, removes nitrogen from the air, concentrates the oxygen in the air, and supplies highly concentrated oxygen to the oxygen supply line 6. There are no particular limitations on the method of concentrating oxygen using the oxygen concentrator 4, but it may be, for example, a cryogenic separation method in which the air is cooled to an extremely low temperature (generally -170°C or lower), liquefied, and separated by distillation, an adsorption separation method in which nitrogen is selectively adsorbed by an adsorbent such as zeolite to separate the air, or a membrane separation method that utilizes differences in permeation speed in polymer membranes such as polyimide.

[0017] The oxygen supply line 6 is formed of, for example, piping, and connects the oxygen concentrator 4 and the combustor 10. The oxygen supply line 6 supplies oxygen (high-concentration oxygen concentrated by the oxygen concentrator 4) from the oxygen concentrator 4 to the combustor 10. The concentration of oxygen supplied from the oxygen concentrator 4 to the combustor 10 via the oxygen supply line 6 may be higher than the oxygen concentration in air, and may be preferably 70% or higher, more preferably 90% or higher.

[0018] The hydrogen supply line 8 is configured, for example, by piping, and connects a hydrogen supply source (not shown) to the combustor 10. The hydrogen supply line 8 supplies hydrogen from the hydrogen supply source to the combustor 10. The concentration of hydrogen supplied from the hydrogen supply line 8 to the combustor 10 may be, for example, 90% or more, preferably 95% or more, and more preferably 100%.

[0019] The combustor 10 burns hydrogen supplied from a hydrogen supply line 8 using oxygen supplied from an oxygen supply line 6 to generate steam. No supply line for supplying hydrocarbon fuel is connected to the combustor 10, and the combustor 10 is a hydrogen-only combustor. Steam compressed by a compressor 12 is also supplied to the combustor 10 to adjust the combustion temperature. The steam generated by burning hydrogen in the combustor 10 is discharged from the combustor 10 and introduced into a steam turbine 18.

[0020] The steam turbine 18 is driven by steam discharged from the combustor 10. The steam turbine 18 has a plurality of stages, each including a plurality of steam expansion blades (not shown). The steam turbine 18 corresponds to a typical gas turbine in which one or more stages 18b, each including a plurality of steam expansion blades, are provided coaxially with an expansion stage 18a of the combustion gas downstream of the expansion stage 18a, and expands the steam to a pressure equivalent to that of a general condensing turbine, thereby recovering energy from the steam. The steam turbine 18 and the compressor 12 are coaxially connected by a rotating shaft 9, and the rotational force of the steam turbine 18 is transmitted to the compressor 12 via the rotating shaft 9 to drive the compressor 12.

[0021] The generator 20 is coupled to the steam turbine 18, and generates electricity as the steam turbine 18 rotates.

[0022] The bleed air circulation line 22 is configured, for example, by piping, and connects the middle stage of the steam turbine 18 and the inlet of the compressor 12. The bleed air circulation line 22 supplies steam bled from the middle stage of the steam turbine 18 to the compressor 12. The compressor 12 compresses the steam bled from the bleed air circulation line 22 and supplies it to the combustor 10. In this way, a portion of the steam in the steam turbine system 2 circulates within the steam turbine system 2 by passing through the combustor 10, the steam turbine 18, the bleed air circulation line 22, and the compressor 12 in this order and returning to the combustor 10. The middle stage of the steam turbine 18 refers to a stage located between the first stage and the final stage of the steam turbine 18.

[0023] The startup air line 24 is configured, for example, by piping, and connects a startup air supply source (not shown) to the compressor 12. The startup air line 24 can start the steam turbine 18 by supplying startup air (compressed air) to the compressor 12 when the steam turbine 18 and the oxygen concentrator 4 are not operating. When the steam turbine 18 is operating, startup air is not supplied from the startup air line 24 to the compressor 12, and steam is supplied to the compressor 12 from the extraction air circulation line 22 as described above.

[0024] Even if the oxygen concentrator 4 cannot continue to operate due to a malfunction or other reason, the steam turbine 18 can continue to operate by closing the extracted air circulation line 22 and supplying air to the compressor 12 from the start-up air line 24 and hydrogen from the hydrogen supply line 8.

[0025] The condenser 26 is supplied with steam discharged from the steam turbine 18 (steam that has passed through the final stage of the steam turbine 18). The condenser 26 condenses the steam discharged from the steam turbine 18 through heat exchange with a cooling medium (such as water). The condensed water condensed in the condenser 26 may be used for any appropriate purpose or may be discarded.

[0026] The vacuum device 28 is provided in the exhaust return line 30 and is constituted by, for example, a vacuum pump. The vacuum device 28 draws a vacuum from the internal space of the condenser 26, thereby sucking in water vapor (a part of the water vapor discharged from the steam turbine 18), oxygen (excess oxygen that has passed through the combustor 10 and the steam turbine 18 without being used for combustion in the combustor 10), and a trace amount of nitrogen (a trace amount of nitrogen that has been supplied from the oxygen supply line 6 and passed through the combustor 10 and the steam turbine 18) from the internal space of the condenser 26.

[0027] The exhaust gas return line 30 is formed of, for example, piping, and connects the condenser 26 and the oxygen concentrator 4. The exhaust gas return line 30 is configured to return the exhaust gas (water vapor, oxygen, and a trace amount of nitrogen) from the vacuum device 28 to the oxygen concentrator 4. In other words, the exhaust gas return line 8 is configured to return the water vapor, oxygen, and a trace amount of nitrogen that have been supplied to the condenser 26 via the combustor 10 and the steam turbine 18 from the condenser 26 to the oxygen concentrator 4.

[0028] Next, the effects achieved by the steam turbine system 2 will be described. According to the steam turbine system 2, by burning hydrogen (fuel hydrogen) supplied from the hydrogen supply line 8 in the combustor using oxygen supplied from the oxygen supply line 6, it is possible to generate high-temperature, high-pressure steam while suppressing the generation of carbon dioxide and nitrogen oxides compared to when a hydrocarbon fuel is burned with air containing a large amount of nitrogen. Furthermore, because air containing a large amount of nitrogen is not used for combustion in the combustor 10, it is possible to reduce exhaust gas loss caused by nitrogen and the like flowing into the combustor 10 compared to a general gas turbine.

[0029] In addition, since a condenser 26 is provided downstream of the steam turbine 18 into which the steam generated in the combustor 10 flows, the steam can be expanded in the steam turbine 18 to a low pressure equivalent to that of a general condensing turbine, making it possible to recover a large amount of energy from the steam.

[0030] Therefore, a highly efficient steam turbine system 2 that can suppress the generation of carbon dioxide and nitrogen oxides can be realized.

[0031] Furthermore, for example, in conventional gas turbine systems, a high excess air ratio is required to optimize the combustion temperature of the combustor. In this case, nitrogen contained in the air not only generates nitrogen oxides but also increases the heat loss of dry gas accompanying the exhaust.

[0032] In contrast, according to the steam turbine system 2, steam supplied from the steam turbine 18 via the extraction air circulation line 22 can be compressed by the compressor 12, and the compressed steam can be supplied to the combustor 10. Therefore, a portion of the steam in the steam turbine system 2 can be circulated within the steam turbine system 2 by returning it to the combustor 10 through the combustor 10, the steam turbine 18, the extraction air circulation line 22, and the compressor 12 in this order. Therefore, the combustion temperature of the combustor 10 can be adjusted using the steam passing through the extraction air circulation line 22, and it is not necessary to supply excess oxygen to the combustor for the purpose of adjusting the combustion temperature of the combustor, as in conventional gas turbine systems, and a more highly efficient steam turbine system 2 can be realized.

[0033] Furthermore, the specific heat of steam is about twice as high as that of air, and the temperature of the combustor 10 can be efficiently controlled with a small amount of gas, thereby improving the output and efficiency of the steam turbine system 2.

[0034] In addition, the steam extracted from the steam turbine 18 is recompressed and then reheated in the combustor 10 for use, thereby achieving the same function as a reheater in a steam turbine power generation system equipped with a combustion boiler, thereby improving the efficiency of the steam turbine system 2.

[0035] Furthermore, when high-concentration hydrogen is burned, the combustion speed of hydrogen is generally high, and so there is a risk of flashback occurring depending on the mixing conditions with oxygen and the flame conditions. However, by using the bleed air circulation line 22 as described above to return and circulate the water vapor to the combustor 10, the occurrence of flashback can be suppressed.

[0036] In addition, by providing a rotating shaft 9 that coaxially connects the compressor 12 and the steam turbine 18, the rotational force of the steam turbine 18 can be utilized to compress steam using the compressor 12, thereby improving the efficiency of the steam turbine system 2.

[0037] Furthermore, by taking in air into the oxygen concentrator 4, highly concentrated oxygen can be supplied to the combustor 10 from the oxygen supply line 6. This makes it possible to suppress the generation of nitrogen oxides and also reduce exhaust gas losses caused by nitrogen, thereby realizing a highly efficient steam turbine system 2.

[0038] Furthermore, in a typical gas turbine system, the oxygen and nitrogen contained in the excess air passing through the combustor is released into the atmosphere, resulting in heat loss. However, in the steam turbine system 2, the exhaust from the vacuum device 28 is water vapor, oxygen, and a trace amount of nitrogen, and the oxygen concentration in the exhaust is higher than that of the air. Therefore, by returning the exhaust from the vacuum device 28 to the oxygen concentrator 4, the excess oxygen that left the combustor 10 can be recovered and effectively utilized.

[0039] FIG. 2 is a schematic configuration diagram of a steam turbine system 2 (2B) according to another embodiment. In the steam turbine system 2 (2B) shown in Figure 2, symbols that are common to each component of the steam turbine system 2 (2A) shown in Figure 1 indicate the same components as those of the steam turbine system 2 (2A) unless otherwise specified, and explanations thereof will be omitted.

[0040] The steam turbine system 2 (2B) shown in Fig. 2 includes a hydrogen vaporizer 32 provided in a hydrogen supply line 8. The hydrogen supply line 8 is connected to a liquid hydrogen supply source upstream of the hydrogen vaporizer 32, and the hydrogen vaporizer 32 is configured to perform heat exchange between the water vapor flowing in the extracted air circulation line 22 and the liquid hydrogen flowing in the hydrogen supply line 8, thereby utilizing the heat of the water vapor flowing in the extracted air circulation line 22 to vaporize the liquid hydrogen flowing in the hydrogen supply line 8. The hydrogen supply line 8 supplies the hydrogen vaporized in the hydrogen vaporizer 32 to the combustor 10.

[0041] According to the steam turbine system 2 (2B), by using the steam flowing through the extraction circulation line 22 as a heat source for the liquid hydrogen, it is possible to effectively recover heat from the steam, and also to lower the temperature of the steam supplied to the compressor 12, thereby increasing the compression efficiency of the steam in the compressor 12.

[0042] Moreover, in the steam turbine system 2 (2B), the above-described effects achieved by the steam turbine system 2 (2A) can be similarly obtained.

[0043] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0044] For example, the steam turbine system 2 (2A, 2B) described above is exemplified as having an oxygen concentrator 4, but the oxygen concentrator 4 is not an essential component of the steam turbine system 2, and the oxygen supply line 6 may be configured to supply oxygen produced outside the steam turbine system 2 to the combustor 10.

[0045] Furthermore, for example, the steam turbine system 2 (2A, 2B) described above was provided with a startup air line 24, but if oxygen can be supplied to the combustor 10 when the steam turbine 18 is started, such as when the oxygen concentrator 4 can be operated using electricity other than that generated by the generator 20, the startup air line 24 does not need to be provided.

[0046] Furthermore, in the steam turbine system 2 (2A, 2B) described above, the exhaust from the vacuum device 28 is returned to the oxygen concentrator 4 via the exhaust return line 30, but the exhaust from the vacuum device 28 may be released into the atmosphere without providing the exhaust return line 30.

[0047] The contents described in each of the above embodiments can be understood, for example, as follows.

[0048] (1) A steam turbine system according to at least one embodiment of the present disclosure, a hydrogen supply line (e.g., the hydrogen supply line 8 described above) configured to supply hydrogen; an oxygen supply line configured to supply oxygen (e.g., the oxygen supply line 6 described above); a combustor (e.g., the combustor 10 described above) configured to combust hydrogen supplied from the hydrogen supply line with oxygen supplied from the oxygen supply line; a steam turbine (e.g., the steam turbine 18 described above) driven by steam exhausted from the combustor; a condenser (e.g., condenser 26 described above) configured to condense water vapor discharged from the steam turbine; Equipped with.

[0049] According to the steam turbine system described in (1) above, by burning hydrogen (fuel hydrogen) supplied from a hydrogen supply line in a combustor using oxygen supplied from an oxygen supply line, it is possible to generate high-temperature, high-pressure steam while suppressing the generation of carbon dioxide and nitrogen oxides compared to when a hydrocarbon fuel is burned with air containing a large amount of nitrogen. Furthermore, because air containing a large amount of nitrogen is not used for combustion in the combustor, it is possible to reduce exhaust gas losses caused by nitrogen, etc., flowing into the combustor compared to a general gas turbine.

[0050] In addition, since a condenser is provided downstream of the steam turbine into which the steam generated in the combustor flows, the steam can be expanded in the steam turbine to the same extent as a conventional condensing turbine, allowing a large amount of energy to be recovered from the steam.

[0051] Therefore, a highly efficient steam turbine system capable of suppressing the generation of carbon dioxide and nitrogen oxides can be realized.

[0052] (2) In some embodiments, in the steam turbine system described in (1), a compressor (e.g., compressor 12 described above); an extraction circulation line (for example, the above-mentioned extraction circulation line 22) that connects a middle stage of the steam turbine and the compressor and is configured to supply steam extracted from the middle stage of the steam turbine to the compressor; Equipped with The compressor is configured to compress the steam supplied from the extraction circulation line and supply the compressed steam to the combustor.

[0053] For example, in conventional gas turbine systems, a high excess air ratio is required to optimize the combustion temperature of the combustor. In this case, nitrogen contained in the air not only generates nitrogen oxides but also increases the heat loss of dry gas accompanying the exhaust.

[0054] In contrast, according to the steam turbine system described in (2) above, steam supplied from the steam turbine via the extraction steam circulation line can be compressed by the compressor, and the compressed steam can be supplied to the combustor. Therefore, a portion of the steam in the steam turbine system can be circulated within the steam turbine system by returning it to the combustor by passing through the combustor, the steam turbine, the extraction steam circulation line, and the compressor in that order. Therefore, the combustion temperature of the combustor can be adjusted using the steam passing through the extraction steam circulation line, and it is not necessary to supply excess oxygen to the combustor for the purpose of adjusting the combustion temperature of the combustor, as in conventional gas turbine systems, and a more efficient steam turbine system can be realized.

[0055] In addition, the specific heat of steam is about twice as high as that of air, allowing for efficient temperature control of the combustor with a small amount of gas, thereby improving the output and efficiency of the steam turbine system.

[0056] In addition, the steam extracted from the steam turbine is recompressed and then reheated in the combustor for use, thereby achieving the same function as a reheater in a steam turbine power generation system equipped with a combustion boiler, thereby improving the efficiency of the steam turbine system.

[0057] Furthermore, when high-concentration hydrogen is burned, the combustion rate of hydrogen is generally high, so there is a risk of flashback depending on the mixing conditions with oxygen and the flame conditions. However, by using the bleed air circulation line as described above to return and circulate the water vapor to the combustor, the occurrence of flashback can be suppressed.

[0058] (3) In some embodiments, in the steam turbine system described in (2) or (3), The steam turbine system according to claim 2, further comprising a rotating shaft (for example, the above-mentioned rotating shaft 9) that coaxially connects the compressor and the steam turbine.

[0059] According to the steam turbine system described in (3) above, the rotational force of the steam turbine can be used to compress the steam by the compressor, thereby improving the efficiency of the steam turbine system.

[0060] (4) In some embodiments, in the steam turbine system according to any one of (1) to (3), the hydrogen vaporizer (for example, the hydrogen vaporizer 32 described above) for exchanging heat between the water vapor flowing through the extraction circulation line and the liquid hydrogen flowing through the hydrogen supply line; The hydrogen supply line is configured to supply hydrogen vaporized in the hydrogen vaporizer to the combustor.

[0061] According to the steam turbine system described in (4) above, by using the steam flowing through the extraction circulation line as a heat source for the liquid hydrogen, it is possible to effectively recover heat from the steam, and also to lower the temperature of the steam supplied to the compressor, thereby increasing the compression efficiency of the steam in the compressor.

[0062] (5) In some embodiments, in the steam turbine system according to any one of (2) to (4), The steam turbine further includes a startup air line capable of supplying compressed air to the compressor when the steam turbine is not operating.

[0063] According to the steam turbine system described in (5) above, even when the steam turbine is stopped and steam is not flowing through the extraction air circulation line, the steam turbine can be started by supplying compressed air to the compressor from the start-up air line.

[0064] (6) In some embodiments, in the steam turbine system according to any one of (1) to (5), further comprising an oxygen concentrator (e.g., oxygen concentrator 4 described above); The oxygen supply line is configured to supply oxygen from the oxygen concentrator to the combustor.

[0065] According to the steam turbine system described in (6) above, for example, by taking in air or the like into an oxygen concentrator, highly concentrated oxygen can be supplied to the combustor from the oxygen supply line, which makes it possible to suppress the generation of nitrogen oxides and reduce exhaust gas losses caused by nitrogen, thereby realizing a highly efficient steam turbine system.

[0066] (7) In some embodiments, in the steam turbine system according to any one of (1) to (6), a vacuum device (e.g., the vacuum device 28 described above) configured to vacuum the interior space of the condenser; an exhaust return line (e.g., exhaust return line 30 described above) configured to return the exhaust of the vacuum device to the oxygen concentrator; Further provided with:

[0067] In a typical gas turbine system, the oxygen and nitrogen contained in the excess air are released into the atmosphere, resulting in heat loss. However, in the steam turbine system described in (7) above, the exhaust from the vacuum device is water vapor, oxygen, and trace amounts of nitrogen, and the oxygen concentration in the exhaust is higher than that of the air. Therefore, by returning the exhaust from the vacuum device to the oxygen concentrator, the excess oxygen that left the combustor can be recovered and effectively utilized. [Explanation of symbols]

[0068] 2. Steam turbine system 4. Oxygen concentrators 6. Oxygen supply line 8 Hydrogen supply line 9 Rotation Axis 10 Combustor 12 Compressor 18 Steam Turbine 20. Generator 22 Extraction air circulation line 24 Starting air line 26 Condenser 28 Vacuum device 30 Exhaust return line 32 Hydrogen vaporizer

Claims

1. a hydrogen supply line configured to supply hydrogen; an oxygen supply line configured to supply oxygen; a combustor configured to combust the hydrogen supplied from the hydrogen supply line using the oxygen supplied from the oxygen supply line; a steam turbine driven by the steam discharged from the combustor; a condenser configured to condense water vapor discharged from the steam turbine; Equipped with A compressor; an extraction circulation line that connects a middle stage of the steam turbine and the compressor and is configured to supply steam extracted from the middle stage of the steam turbine to the compressor; Equipped with the compressor is configured to compress the steam extracted from the extraction circulation line and supply the steam to the combustor, a hydrogen vaporizer that performs heat exchange between the water vapor flowing through the extracted air circulation line and the liquid hydrogen flowing through the hydrogen supply line; the hydrogen supply line is configured to supply hydrogen vaporized in the hydrogen vaporizer to the combustor; Steam turbine system.

2. The steam turbine system of claim 1 , further comprising a rotating shaft coaxially connecting the compressor and the steam turbine.

3. The steam turbine system according to claim 1 or 2, further comprising a startup air line capable of supplying compressed air to the compressor when the steam turbine is not operating.

4. A hydrogen supply line configured to supply hydrogen; an oxygen supply line configured to supply oxygen; a combustor configured to combust the hydrogen supplied from the hydrogen supply line using the oxygen supplied from the oxygen supply line; a steam turbine driven by the steam discharged from the combustor; a condenser configured to condense water vapor discharged from the steam turbine; Equipped with further comprising an oxygen concentrator; the oxygen supply line is configured to supply oxygen from the oxygen concentrator to the combustor; a vacuum device configured to vacuum the interior space of the condenser; an exhaust return line configured to return the exhaust of the vacuum device to the oxygen concentrator; The steam turbine system further comprises:

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