Liquefied gas seal system

Abstract

To provide a liquefied gas seal that reduces leakage of liquefied gas. [Solution] The liquefied gas sealing system 10 seals the liquefied gas chamber 7 around a shaft 4 that penetrates and rotates from inside to outside the liquefied gas chamber 7. The liquefied gas sealing system 10 includes a first labyrinth 11 communicating with the inside of the liquefied gas chamber 7, a second labyrinth 13 communicating with the liquefied gas chamber 7 via the first labyrinth 11, and a heating region 12 for the liquefied gas located between the first labyrinth 11 and the second labyrinth 13. Preferably, in the vertical direction, the second labyrinth 13 is located above the heating region 12.

Description

【Technical Field】 【0001】 This specification discloses a liquefied gas seal system. 【Background Art】 【0002】 Patent Document 1 discloses a turbo pump. This turbo pump is used for supplying liquefied gases such as liquid hydrogen and liquid oxygen. This turbo pump includes an impeller for pumping the liquefied gas, a shaft for rotating the impeller, and a bearing for supporting the shaft. This turbo pump has a labyrinth. This labyrinth suppresses the leakage of liquefied gas around the shaft. This turbo pump further includes a slinger located between the labyrinth and the bearing, and a decompression chamber in which this slinger is accommodated. This turbo pump has a partition wall between the decompression chamber and the bearing chamber, and suppresses the fluid movement from the decompression chamber to the bearing chamber. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2016-41909 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 In the turbo pump of Patent Document 1, the shaft penetrates the wall from the inside to the outside of the liquefied gas chamber. A gap occurs around this shaft. The labyrinth suppresses the leakage of liquefied gas from this gap. However, the labyrinth is a non-contact seal. It is difficult to completely prevent the leakage of liquefied gas with a labyrinth. Further reduction of leakage is required for such a liquefied gas seal. 【0005】 The intention of the applicant of this application is to provide a liquefied gas seal system that reduces the leakage of liquefied gas. 【Means for Solving the Problems】 【0006】 The liquefied gas sealing system disclosed herein seals the liquefied gas chamber around a shaft that penetrates and rotates from inside to outside the liquefied gas chamber. This liquefied gas seal is A first labyrinth communicating with the liquefied gas chamber, A second labyrinth is connected to the liquefied gas chamber via the first labyrinth, A heating region for liquefied gas located between the first labyrinth and the second labyrinth Includes. [Effects of the Invention] 【0007】 This liquefied gas sealing system can reduce liquefied gas leakage. [Brief explanation of the drawing] 【0008】 [Figure 1] Figure 1 is a configuration diagram showing a liquefied gas turbine equipped with a liquefied gas seal system according to one embodiment. [Figure 2] Figure 2 is a partial cross-sectional view showing the liquefied gas sealing system of Figure 1. [Figure 3] Figure 3 is a diagram showing the configuration of the liquefied gas seal system shown in Figure 1. [Figure 4] Figure 4 is a partial cross-sectional view showing a liquefied gas seal system according to another embodiment. [Modes for carrying out the invention] 【0009】 Preferred embodiments will be described in detail below, with reference to drawings as appropriate. 【0010】 Figure 1 shows a liquefied gas turbine 1. This liquefied gas turbine 1 is used, for example, in a liquid hydrogen production facility that obtains liquid hydrogen. This liquefied gas turbine 1 is explained using liquid hydrogen as an example. However, the liquefied gas used in the liquefied gas turbine 1 is not limited to liquid hydrogen. 【0011】 The liquefied gas turbine 1 comprises a turbine 2, a blower 3, a shaft 4, a bearing 5, a heat exchanger 6, a liquefied gas chamber 7, a bearing chamber 8, and a brake chamber 9. Furthermore, the liquefied gas turbine 1 is equipped with a liquefied gas seal system 10. In this liquefied gas turbine 1, the liquefied gas chamber 7, the bearing chamber 8, and the brake chamber 9 are located in the vertical direction, from bottom to top. The turbine 2 is located in the liquefied gas chamber 7. The bearing 5 is located in the bearing chamber 8. The blower 3 and the heat exchanger 6 are located in the brake chamber 9. 【0012】 The shaft 4 is supported axially and radially by the bearing 5. The shaft 4 extends vertically. The shaft 4 is rotatable. The shaft 4 extends from the liquefied gas chamber 7 to the brake chamber 9, with the bearing chamber 8 in between. The shaft 4 connects the turbine 2 and the blower 3. 【0013】 The bearing 5 is not particularly limited, but for example, a fluid bearing may be used. The fluid in the fluid bearing is not particularly limited, but for example, hydrogen gas. The bearing chamber 8 is filled with hydrogen gas. 【0014】 The liquefied gas seal system 10 is positioned around the shaft 4 between the inside and outside of the liquefied gas chamber 7. In the vertical direction, the liquefied gas seal system 10 is positioned above the liquefied gas chamber 7. 【0015】 In this liquefied gas turbine 1, high-pressure, cryogenic liquid hydrogen flows into the liquefied gas chamber 7 from the inlet 7A. This liquid hydrogen rotates the turbine 2. By rotating the turbine 2, kinetic energy is obtained from the liquid hydrogen, and the pressure of the liquid hydrogen decreases. The liquid hydrogen with reduced pressure flows out from the outlet 7B. 【0016】 On the one hand, the rotation of the turbine 2 causes the shaft 4 and the blower 3 to rotate. The brake chamber 9 is filled with hydrogen gas. The blower 3 causes the hydrogen gas to flow in the brake chamber 9. Thermal energy is obtained from the flowing hydrogen gas by the heat exchanger 6. In this way, the pressure of the liquid hydrogen in the liquefied gas chamber 7 is reduced and energy is extracted from the liquid hydrogen. Note that the hydrogen gas in the brake chamber 9 is an example of a fluid, and the fluid in the brake chamber 9 is not limited to hydrogen gas. 【0017】 This liquefied gas turbine 1 can reduce the pressure of the liquid hydrogen while extracting energy from the high-pressure liquid hydrogen. By using the liquefied gas turbine 1, the liquefied hydrogen production facility can improve energy efficiency. 【0018】 FIG. 2 shows a cross-sectional view of the liquefied gas seal system 10. FIG. 2 shows the center line L of the shaft 4. FIG. 2 is a cross-sectional view along the center line L. The liquefied gas seal system 10 includes a first labyrinth 11, a heating region 12, and a second labyrinth 13. In this liquefied gas seal system 10, in the vertical direction, the first labyrinth 11, the heating region 12, and the second labyrinth 13 are located in this order from bottom to top. 【0019】 The liquefied gas turbine 1 includes a housing 14. The first labyrinth 11, the heating region 12, and the second labyrinth 13 are formed between the outer peripheral surface 4A of the shaft 4 and the inner peripheral surface 14A of the housing 14. This liquefied gas seal system 10 further includes a heat insulating material 15 and a heater 16. 【0020】 The first labyrinth 11 is located between the liquefied gas chamber 7 and the heating region 12. The first labyrinth 11 communicates with the liquefied gas chamber 7 around the shaft 4. The first labyrinth 11 is a combination of a large number of concave and convex gaps between the outer peripheral surface 4A of the shaft 4 and the inner peripheral surface 14A of the housing 14. In FIG. 2, the first labyrinth 11 is the concavity and convexity from the inner peripheral surface 14A of the housing 14, but is not limited to the concavity and convexity in FIG. 2. The concavity and convexity of the first labyrinth 11 may be the concavity and convexity from the outer peripheral surface 4A of the shaft 4, or may be the concavity and convexity from both the outer peripheral surface 4A of the shaft 4 and the inner peripheral surface 14A of the housing 14. 【0021】 The heating region 12 is located between the first labyrinth 11 and the second labyrinth 13. The heating region 12 communicates with the first labyrinth 11 and the second labyrinth 13. The heating region 12 is the space between the outer peripheral surface 4A of the shaft 4 and the inner peripheral surface 14A of the housing 14. 【0022】 The second labyrinth 13 is located between the heating region 十二 and the bearing chamber 8. The second labyrinth 13 communicates with the bearing chamber 8. The second labyrinth 13 communicates with the liquefied gas chamber 7 through the first labyrinth 11 and the heating region 12. The second labyrinth 13 is a combination of a large number of concave and convex gaps between the outer peripheral surface 4A of the shaft 4 and the inner peripheral surface 14A of the housing 14. In FIG. 2, the second labyrinth 13 is the concavity and convexity from the inner peripheral surface 14A of the housing 14, but is not limited to the concavity and convexity in FIG. 2. The concavity and convexity of the second labyrinth 13 may be the concavity and convexity from the outer peripheral surface 4A of the shaft 4, or may be the concavity and convexity from both the outer peripheral surface 4A of the shaft 4 and the inner peripheral surface 14A of the housing 14. 【0023】 The heat insulating material 15 is located between the liquefied gas chamber 7 and the first labyrinth 11. The heat insulating material 15 insulates between the liquefied gas chamber 7 and the heating region 12. 【0024】 The heater 16 has a heat transfer element 16A embedded in the housing 14. The heater 16 can heat the portion of the housing 14 surrounding the heating region 12. The heater 16 can heat the liquid hydrogen in the heating region 12 through the housing 14. The heater 16 is not particularly limited as long as it can heat the liquid hydrogen in the heating region 12. For example, the heater 16 may have a flow path for a heat transfer medium located within the housing 14. 【0025】 As shown in Figure 3, the liquefied gas seal system 10 includes a vent line 17 and a valve 18. As shown in Figure 2, the vent line 17 is a flow path communicating with the heating region 12. The valve 18 is located in the vent line 17. The valve 18 can open and close the vent line 17. When the valve 18 opens the vent line 17, the liquid hydrogen in the heating region 12 can be discharged through the vent line 17. 【0026】 In the liquefied gas turbine 1 shown in Figure 1, as described above, liquid hydrogen flows into the liquefied gas chamber 7 from the inlet 7A and out from the outlet 7B. In the liquefied gas seal system 10 shown in Figure 2, the liquid hydrogen in the liquefied gas chamber 7 leaks to the heating region 12 through the first labyrinth 11. The first labyrinth 11 suppresses this leakage of liquid hydrogen. 【0027】 In this liquefied gas seal system 10, the rotation of the shaft 4 generates viscous friction in the liquid hydrogen between the outer circumferential surface 4A of the shaft 4 and the inner circumferential surface 14A of the housing 14. This viscous friction is the friction that occurs between the liquid hydrogen and the surrounding liquid hydrogen as it moves. This viscous friction heats the liquid hydrogen. In this heated region 12, the temperature rises as it heats up, and the density of the liquid hydrogen decreases. 【0028】 The liquid hydrogen in the heating region 12 leaks out of the liquefied gas chamber 7 through the second labyrinth 13. In this heating region 12, the area outside the liquefied gas chamber 7 is the bearing chamber 8, but is not limited to the bearing chamber 8. The second labyrinth 13 suppresses the leakage of liquid hydrogen to the outside of the liquefied gas chamber 7. 【0029】 In this liquefied gas seal system 10, when the pressure of the liquid hydrogen in the heating region 12 is higher than a predetermined pressure, the valve 18 opens the vent line 17 (see Figure 3). The liquid hydrogen in the heating region 12 is discharged through the vent line 17. When the pressure of the liquid hydrogen in the heating region 12 is below the predetermined pressure, the valve 18 closes the vent line 17. 【0030】 The liquefied gas seal system 10 includes a heating region 12 located between the first labyrinth 11 and the second labyrinth 13. In the heating region 12, liquid hydrogen is heated. In the heating region 12, the density of liquid hydrogen decreases. The liquid hydrogen is gradually depressurized as it passes through the second labyrinth 13. The second labyrinth 13 reduces liquid hydrogen leakage by gradually depressurizing the liquid hydrogen. By reducing the density of liquid hydrogen, the sealing effect due to the depressurization of liquid hydrogen is improved in the second labyrinth 13. In the liquefied gas seal system 10, the second labyrinth 13 can exhibit high sealing performance. 【0031】 In the heated region 12, the distance between the outer circumferential surface 4A of the shaft 4 and the inner circumferential surface 14A of the housing 14 should be such that viscous friction occurs in the liquid hydrogen. This distance is determined appropriately depending on the rotational speed of the shaft 4 and the type and state of the liquefied gas. 【0032】 In the liquefied gas seal system 10, the second labyrinth 13 is located above the heating region 12 in the vertical direction. In the heating region 12, the less dense liquid hydrogen flows upwards above the denser liquid hydrogen. Therefore, the less dense liquid hydrogen can easily reach the second labyrinth 13. As a result, the second labyrinth 13 can exhibit high sealing performance. Therefore, it is preferable for the second labyrinth 13 to be located above the heating region 12. 【0033】 The liquefied gas sealing system 10 includes an insulating material 15 that insulates the space between the liquefied gas chamber 7 and the heating region 12. The insulating material 15 suppresses the heating of the liquid hydrogen in the liquefied gas chamber 7. The position of the insulating material 15 does not need to be such that it can insulate the space between the liquefied gas chamber 7 and the heating region 12. The insulating material 15 may be located, for example, between the first labyrinth 11 and the heating region 12. 【0034】 In the liquefied gas turbine 1, it is undesirable for the liquid hydrogen heated in the heating region 12 to flow back into the liquefied gas chamber 7. From this viewpoint, in the liquefied gas seal system 10, it is preferable that the sealing performance of the first labyrinth 11 is higher than that of the second labyrinth 13. This sealing performance can be evaluated by the amount of liquid hydrogen leaking per unit time. Therefore, it is preferable that the opening area of ​​the first labyrinth 11 is smaller than the opening area of ​​the second labyrinth 13. Similarly, it is preferable that the length of the first labyrinth 11 is longer than the length of the second labyrinth 13. 【0035】 In this heating region 12, the liquid hydrogen is agitated between the inner circumferential surface 14A of the housing 14 and the outer circumferential surface 4A of the shaft 4. This agitation generates viscous friction in the liquid hydrogen. The heating region 12 heats the liquid hydrogen by viscous friction. This heating of the liquid hydrogen utilizes the rotation of the shaft 4. The liquefied gas seal system 10 uses the energy of the liquid hydrogen in the liquefied gas chamber 7 to heat the liquid hydrogen in the heating region 12. Furthermore, in this heating region 12, viscous friction of the liquid hydrogen is generated between the inner circumferential surface 14A of the housing 14 and the outer circumferential surface 4A of the shaft 4. This liquefied gas seal system 10 can heat liquid hydrogen with a simple configuration. Thus, from the viewpoint of energy saving and a simple configuration, it is preferable to generate viscous friction of the liquid hydrogen between the inner circumferential surface 14A of the housing 14 and the outer circumferential surface 4A of the shaft 4 in the heating region 12. 【0036】 The heating effect in this heating region 12 can be improved by making the surface roughness of the inner circumferential surface 14A of the housing 14 and the outer circumferential surface 4A of the shaft 4 rougher. From this viewpoint, it is preferable to make the surface roughness of both or either the inner circumferential surface 14A and the outer circumferential surface 4A rougher. This surface roughness can be evaluated by comparing it with the surface roughness of the inner circumferential surface 14A of the housing 14 and the outer circumferential surface 4A of the shaft 4, which face each other between the liquefied gas chamber 7 and the first labyrinth 11. It is preferable that the surface roughness of the inner circumferential surface 14A in the heating region 12 is rougher than the surface roughness of the inner circumferential surface 14A between the liquefied gas chamber 7 and the first labyrinth 11. It is preferable that the surface roughness of the outer circumferential surface 4A in the heating region 12 is rougher than the surface roughness of the outer circumferential surface 4A between the liquefied gas chamber 7 and the first labyrinth 11. 【0037】 This liquefied gas seal system 10 includes a heater 16. The heater 16 can easily adjust the temperature of the liquid hydrogen. This allows the heater 16 to suppress fluctuations in sealing performance due to the rotational speed of the shaft 4. 【0038】 The heater 16 has a heat transfer element 16A that heats the portion of the housing 14 surrounding the heating region 12. The heat transfer element 16A heats the liquid hydrogen in the heating region 12 through the housing 14. The heater 16 may also have a heat transfer element 16A located inside the housing 14 that directly heats the liquid hydrogen in the heating region 12. A heat transfer element 16A made of a material with high thermal conductivity can efficiently heat liquid hydrogen at extremely low temperatures. A heat transfer element 16A made of a material with high thermal conductivity allows for miniaturization of the heater 16. From these viewpoints, the material of the heat transfer element 16A is preferably copper with a purity of 99% or more, or aluminum with a purity of 99% or more. Examples of materials for the heat transfer element 16A include oxygen-free copper and tough pitch copper. 【0039】 In this liquefied gas sealing system 10, liquid hydrogen is gradually depressurized by passing through the second labyrinth 13. The second labyrinth 13 reduces leakage of liquid hydrogen by gradually depressurizing it. Liquid hydrogen, which has a low density, can achieve a high depressurization effect in the second labyrinth 13. Therefore, the second labyrinth 13 can exhibit high sealing performance for liquid hydrogen with a low density. The heating region 12 heats the liquid hydrogen, thereby enabling the second labyrinth 13 to exhibit high sealing performance. 【0040】 Supercritical liquid hydrogen does not undergo a clear state change between liquid and gas phases with respect to temperature changes. On the other hand, the density of supercritical liquid hydrogen changes with increasing temperature. By increasing the temperature, the density of supercritical liquid hydrogen decreases. By increasing the temperature, the second labyrinth 13 can exhibit high sealing performance against supercritical liquid hydrogen. This liquefied gas seal system 10, including the heating region 12, can exhibit high sealing performance against supercritical liquid hydrogen with a simple configuration. 【0041】 The liquefied gas seal system 10 includes an insulating material 15, but it does not have to include the insulating material 15. Also, the liquefied gas seal system 10 includes a heater 16, but it does not have to include the heater 16. Furthermore, the heating region 12 is not limited to a configuration that generates viscous friction in the liquid hydrogen between the outer circumferential surface 4A of the shaft 4 and the inner circumferential surface 14A of the housing 14. The heating region 12 can be any region capable of heating the liquid hydrogen. For example, the liquefied gas seal system 10 may include a heater 16 instead of the outer circumferential surface 4A and inner circumferential surface 14A that generate viscous friction. 【0042】 The liquefied gas turbine 1 comprises a turbine 2 that rotates inside a liquefied gas chamber 7, a blower 3 that rotates outside the liquefied gas chamber 7, a shaft 4 that rotates connecting the turbine 2 and the blower 3, and a liquefied gas seal system 10 that seals the liquefied gas chamber 7 around the shaft 4. In this liquefied gas turbine 1, the turbine 2, blower 3, and shaft 4 can extract energy from high-pressure liquid hydrogen while simultaneously reducing the pressure of the liquid hydrogen. This liquefied gas turbine 1 can contribute to improving energy efficiency. 【0043】 The liquefied gas seal system 10 includes a first labyrinth 11, a heating region 12, and a second labyrinth 13. This allows the liquefied gas seal system 10 to suppress leakage of liquid hydrogen from the liquefied gas chamber 7. 【0044】 The liquid hydrogen production apparatus using this liquefied gas turbine 1 handles cryogenic liquid hydrogen. Cryogenic liquid hydrogen is obtained through numerous processes. Therefore, suppressing leakage of cryogenic liquid hydrogen has a significant impact on the operating cost and economic efficiency of the liquid hydrogen production apparatus. This liquefied gas turbine 1 can improve the operating cost and economic efficiency of the liquid hydrogen production apparatus. 【0045】 Here, a liquefied gas turbine 1, which obtains kinetic energy from liquid hydrogen, was used as an example. However, the applications of this liquefied gas seal system 10 are not limited to the liquefied gas turbine 1. The liquefied gas seal system 10 may also be used in a pump that imparts kinetic energy to liquid hydrogen. The liquefied gas seal system 10 can be widely used in turbomachinery equipped with a shaft 4 that converts fluid energy into kinetic energy and kinetic energy back into fluid energy. 【0046】 Figure 4 shows a cross-sectional view of a liquefied gas seal system 20 according to another embodiment. Here, the liquefied gas seal system 20 will mainly be described in terms of its configuration that differs from that of the liquefied gas seal system 10. Configurations similar to those of the liquefied gas seal system 10 will not be described, and the same reference numerals will be used to describe similar configurations. 【0047】 Figure 4 is a cross-sectional view along the center line L of the shaft 4. The liquefied gas seal system 20 includes a first labyrinth 11, a heating region 21, and a second labyrinth 13. In this liquefied gas seal system 20, the first labyrinth 11, the heating region 21, and the second labyrinth 13 are located in the vertical direction, from bottom to top. 【0048】 The liquefied gas seal system 20 is used, for example, in a liquefied gas turbine 22. The liquefied gas turbine 22 includes a housing 23. The first labyrinth 11, the heating region 21, and the second labyrinth 13 are formed between the outer circumferential surface 4A of the shaft 4 and the inner circumferential surface 23A of the housing 23. The liquefied gas seal system 20 includes a number of stationary blades 24 and a number of rotating blades 25. 【0049】 Each fixed vane 24 protrudes radially inward from the inner circumferential surface 23A of the housing 23. The fixed vanes 24 extend vertically along the inner circumferential surface 23A. The numerous fixed vanes 24 are arranged at intervals in the circumferential direction. Each rotating vane 25 protrudes radially outward from the outer circumferential surface 4A of the shaft 4. The rotating vanes 25 extend vertically along the outer circumferential surface 4A. The numerous rotating vanes 25 are arranged at intervals in the circumferential direction. The fixed vanes 24 and rotating vanes 25 are located within the heating region 21. There is a gap between the fixed vanes 24 and the rotating vanes 25 in the radial direction of the shaft 4. 【0050】 The first labyrinth 11 is located between the liquefied gas chamber 7 and the heating region 21. The heating region 21 is located between the first labyrinth 11 and the second labyrinth 13. The heating region 21 is in communication with the first labyrinth 11 and the second labyrinth 13. The heating region 21 is the region between the outer circumferential surface 4A of the shaft 4 and the inner circumferential surface 14A of the housing 14. The second labyrinth 13 is located between the heating region 21 and the bearing chamber 8. 【0051】 The liquefied gas seal system 20 includes a vent line 26. The vent line 26 is a flow path communicating with the heating region 21. Although not shown, a valve 18 is located in the vent line 26. The valve 18 can open and close the vent line 26. When the valve 18 opens the vent line 26, the liquid hydrogen in the heating region 21 can be discharged through the vent line 26. 【0052】 In this liquefied gas sealing system 20, liquid hydrogen from the liquefied gas chamber 7 leaks into the heating region 21 through the first labyrinth 11. The first labyrinth 11 suppresses the leakage of liquid hydrogen from the liquefied gas chamber 7. 【0053】 In this liquefied gas seal system 20, the rotation of the shaft 4 causes the fixed blades 24 and rotating blades 25 to agitate the liquid hydrogen, thereby heating it. In the heated region 21, the liquid hydrogen is heated and its temperature rises. The density of the heated liquid hydrogen decreases. 【0054】 The liquid hydrogen heated in the heating region 21 leaks out of the liquefied gas chamber 7 (bearing chamber 8) through the second labyrinth 13. The second labyrinth 13 suppresses the leakage of liquid hydrogen from the heating region 21. 【0055】 In this liquefied gas seal system 20, liquid hydrogen is agitated in the heating region 21 by the stationary blades 24 and the rotating blades 25. The agitation heats the liquid hydrogen, causing its temperature to rise. In the heating region 21, the density of the liquid hydrogen decreases. By reducing the density of the liquid hydrogen in the liquefied gas seal system 20, the second labyrinth 13 exhibits high sealing performance. 【0056】 Each stationary vane 24 forms a space between it and other adjacent stationary vanes 24 in the circumferential direction. This space extends vertically along the inner circumferential surface 23A of the housing 23. Low-density liquid hydrogen easily moves upward by flowing through this space. These stationary vanes 24 facilitate the low-density liquid hydrogen to reach the second labyrinth 13. Similarly, the rotating vanes 25 also facilitate the low-density liquid hydrogen to reach the second labyrinth 13. 【0057】 In the heating region 21, the liquid hydrogen was agitated by the stationary blades 24 and the rotating blades 25, but the liquid hydrogen may be agitated by either the stationary blades 24 or the rotating blades 25 alone. The liquefied gas seal system 20 may include either the stationary blades 24 protruding from the inner circumferential surface 23A or the rotating blades 25 protruding from the outer circumferential surface 4A. At least one of the stationary blades 24 or the rotating blades 25 may agitate the liquid hydrogen and raise the temperature of the liquid hydrogen. 【0058】 [Disclosure method] Each of the following embodiments discloses a preferred embodiment. 【0059】 [Aspect 1] A liquefied gas sealing system that seals the liquefied gas chamber around a shaft that penetrates and rotates from the inside to the outside of the liquefied gas chamber, A first labyrinth communicating with the liquefied gas chamber, A second labyrinth is connected to the liquefied gas chamber via the first labyrinth, A heating region for liquefied gas located between the first labyrinth and the second labyrinth A liquefied gas sealing system, including a liquefied gas sealing system. 【0060】 According to the above configuration, the liquefied gas is heated in the heating region. The heated liquefied gas passes through the second labyrinth. This allows the second labyrinth to exhibit high sealing performance. This liquefied gas sealing system can reduce liquefied gas leakage. 【0061】 [Aspect 2] The liquefied gas seal system according to embodiment 1, wherein the second labyrinth is located above the heating region in the vertical direction. 【0062】 According to the above configuration, liquid hydrogen with a lower density reaches the second labyrinth more easily than liquid hydrogen with a higher density. As a result, the second labyrinth can exhibit high sealing performance. 【0063】 [Aspect 3] A liquefied gas sealing system according to embodiment 1 or 2, comprising an insulating material for insulating the space between the liquefied gas chamber and the heating region. 【0064】 According to the above configuration, heating of the liquid hydrogen in the liquefied gas chamber is suppressed. 【0065】 [Aspect 4] A liquefied gas sealing system according to any one of embodiments 1 to 3, wherein the sealing performance of the first labyrinth is higher than the sealing performance of the second labyrinth. 【0066】 According to the above configuration, the inflow of liquid hydrogen from the heating region into the liquefied gas chamber is suppressed. 【0067】 [Aspect 5] The housing comprises an inner circumferential surface that surrounds the outer circumferential surface of the shaft, The liquefied gas seal system according to any one of embodiments 1 to 4, wherein the heating region is a region in which the liquefied gas is heated by viscous friction generated between the inner circumferential surface of the housing and the outer circumferential surface of the shaft. 【0068】 With the above configuration, the energy of the liquid hydrogen in the liquefied gas chamber can be used to heat the liquid hydrogen in the heating region. This allows for heating of liquid hydrogen with a simple configuration. 【0069】 [Aspect 6] The housing comprises an inner circumferential surface that surrounds the outer circumferential surface of the shaft, A liquefied gas seal system according to any one of embodiments 1 to 5, comprising a blade located in the heating region and protruding from at least one of the inner or outer circumferential surface for stirring and heating the liquefied gas. 【0070】 According to the above configuration, liquid hydrogen is stirred by the blades in the heating region. The stirring heats the liquid hydrogen. The density of liquid hydrogen can be reduced in the heating region. Leakage of liquid hydrogen is suppressed. 【0071】 [Aspect 7] A liquefied gas seal system according to any one of embodiments 1 to 6, comprising a heater for heating the liquefied gas in the aforementioned heating region. 【0072】 With the above configuration, the temperature of the liquid hydrogen can be easily adjusted. This liquefied gas seal system can suppress fluctuations in the sealing performance of the second labyrinth due to the rotational speed of the shaft. 【0073】 [Aspect 8] The heater has a heat transfer element, The liquefied gas seal system according to embodiment 7, wherein the material of the heat transfer element is copper with a purity of 99% or more, or aluminum with a purity of 99% or more. 【0074】 According to the above configuration, the heat transfer element can efficiently heat the liquefied gas. This heat transfer element allows for a smaller heater size. 【0075】 [Aspect 9] The first impeller rotates inside the liquefied gas chamber, A second impeller that rotates outside the liquefied gas chamber, A shaft that connects the first impeller and the second impeller and rotates, A liquefied gas seal system that seals the liquefied gas chamber around the shaft, Equipped with, The liquefied gas seal system is A first labyrinth communicating with the liquefied gas chamber, A second labyrinth is connected to the liquefied gas chamber via the first labyrinth, A heating region for liquefied gas located between the first labyrinth and the second labyrinth Turbomachinery, including 【0076】 With the above configuration, the turbomachinery can suppress leakage of liquefied gas from the liquefied gas chamber through the liquefied gas sealing system. This turbomachinery can improve the operating costs and economic efficiency of the liquefied gas production equipment. [Industrial applicability] 【0077】 The liquefied gas sealing system described above can be widely applied as a sealing system to suppress leakage of liquefied gas. [Explanation of symbols] 【0078】 1. 22. Liquefied gas turbine (turbomachinery) 2. Turbine (first impeller) 3. Blower (second impeller) 4. Shaft 7. Liquefied Gas Chamber 8. Bearing chamber 10, 20...Liquefied gas seal system 11...The First Labyrinth 12, 21...Heating area 13...The Second Labyrinth 14, 23... Housing 15. Insulation 16...heater 16A... Heat transfer element 24... Fixed blades 25... Rotating blades

Claims

[Claim 1] A liquefied gas sealing system that seals the liquefied gas chamber around a shaft that penetrates and rotates from the inside to the outside of the liquefied gas chamber, A first labyrinth communicating with the liquefied gas chamber, A second labyrinth is connected to the liquefied gas chamber via the first labyrinth, A heating region for liquefied gas located between the first labyrinth and the second labyrinth A liquefied gas sealing system, including a liquefied gas sealing system. [Claim 2] The liquefied gas seal system according to claim 1, wherein the second labyrinth is located above the heating region in the vertical direction. [Claim 3] The liquefied gas sealing system according to claim 1 or 2, further comprising an insulating material for insulating the space between the liquefied gas chamber and the heating region. [Claim 4] The liquefied gas sealing system according to claim 1 or 2, wherein the sealing performance of the first labyrinth is higher than that of the second labyrinth. [Claim 5] The housing comprises an inner circumferential surface that surrounds the outer circumferential surface of the shaft, The liquefied gas seal system according to claim 1 or 2, wherein the heating region is a region in which the liquefied gas is heated by viscous friction generated between the inner circumferential surface of the housing and the outer circumferential surface of the shaft. [Claim 6] The housing comprises an inner circumferential surface that surrounds the outer circumferential surface of the shaft, The liquefied gas seal system according to claim 1 or 2, comprising a blade located in the heating region and protruding from at least one of the inner or outer circumferential surface for stirring and heating the liquefied gas. [Claim 7] The liquefied gas seal system according to claim 1 or 2, further comprising a heater for heating the liquefied gas in the heating region. [Claim 8] The heater has a heat transfer element, The liquefied gas seal system according to claim 7, wherein the material of the heat transfer element is copper with a purity of 99% or more, or aluminum with a purity of 99% or more. [Claim 9] The first impeller rotates inside the liquefied gas chamber, A second impeller that rotates outside the liquefied gas chamber, A shaft that connects the first impeller and the second impeller and rotates, A liquefied gas seal system that seals the liquefied gas chamber around the shaft, Equipped with, The liquefied gas seal system is A first labyrinth communicating with the liquefied gas chamber, A second labyrinth is connected to the liquefied gas chamber via the first labyrinth, A heating region for liquefied gas located between the first labyrinth and the second labyrinth Turbomachinery, including

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