Power recovery system and floating structure

Abstract

A power recovery system for recovering power from liquefied gas supplied from a liquefied gas storage device that stores liquefied gas, comprising: a first turbine driven by gas obtained by vaporizing the liquefied gas supplied from the liquefied gas storage device; a first leakage gas inlet pipe for guiding the gas leaking from a shaft seal portion of the first turbine; and a gas combustion device for burning the gas guided by the first leakage gas inlet pipe.

Description

Technical Field

[0001] The present invention relates to a power recovery system for recovering power from liquefied gas and a floating structure on water equipped with the power recovery system.

[0002] This application claims priority based on Japanese Patent Application No. 2020-144589 filed with the Japan Patent Office on August 28, 2020, the contents of which are incorporated herein by reference. Background Art

[0003] Liquefied gas (e.g., liquefied natural gas) is liquefied for the purpose of transportation and storage, and when supplied to a supply destination such as a city gas or a thermal power plant, it is heated and vaporized by a heat medium such as seawater. When the liquefied gas is vaporized, power is consumed to drive a pump for the liquefied gas, a pump for seawater, etc. Therefore, the low-temperature energy of the liquefied gas is sometimes recovered instead of being discarded into the seawater (e.g., Patent Document 1).

[0004] Patent Document 1 discloses a cold energy power generation cycle that recovers low temperature energy of liquefied natural gas (LNG) as electricity and an LNG turbine driven by natural gas obtained by heating liquefied natural gas after pressurization by a pump. The cold energy power generation cycle uses seawater as a heat source to heat a secondary medium circulating in a closed loop through an evaporator to evaporate the secondary medium, and after the steam is introduced into a turbine for cold energy power generation to obtain power, it is cooled and condensed by the liquefied natural gas.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-8042

[0008] Technical problem to be solved by the invention

[0009] The LNG turbine disclosed in Patent Document 1 uses natural gas obtained by heating liquefied natural gas after pressurizing it with a pump as the working fluid. Therefore, it is necessary to suppress the leakage of high-pressure and low-temperature natural gas to the outside of the LNG turbine. By using high-performance seals such as expensive mechanical seals and seals with complex structures in the shaft seal of the LNG turbine, the sealing performance of the shaft seal can be ensured. However, if high-performance seals are used in the shaft seal, the structure of the LNG turbine may become complicated and expensive. The complexity of the structure of the LNG turbine may reduce the reliability of the LNG turbine and increase the maintenance cost. Therefore, suppressing the complexity and high cost of the structure of the LNG turbine becomes a technical problem for realizing the LNG turbine. Summary of the invention

[0010] In view of the above situation, the purpose of at least one embodiment of the present invention is to provide a power recovery system and a water floating structure equipped with the power recovery system, wherein the power recovery system can suppress gas leakage of a turbine driven by gas after liquefied gas is vaporized, and can suppress the complexity and high cost of the structure of the turbine.

[0011] Technical means for solving technical problems

[0012] A power recovery system according to one embodiment of the present invention recovers power from liquefied gas supplied from a liquefied gas storage device storing liquefied gas, and comprises:

[0013] a first turbine driven by gas obtained by vaporizing the liquefied gas supplied from the liquefied gas storage device;

[0014] a first leakage gas introduction pipe for guiding the gas leaking from a shaft seal portion of the first turbine; and

[0015] A gas combustion device is provided for burning the gas guided by the first leaked gas introduction pipe.

[0016] A floating structure on water according to an embodiment of the present invention is equipped with the power recovery system.

[0017] Effects of the Invention

[0018] At least one embodiment of the present invention provides a power recovery system and a floating structure having the power recovery system, wherein the power recovery system can suppress gas leakage of a turbine driven by gas from liquefied gas and can suppress the complexity and cost of the structure of the turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram schematically showing the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic structural diagram schematically showing the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic structural diagram schematically showing the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic cross-sectional view schematically showing a cross section of a first turbine along the axis of a rotating shaft in one embodiment of the present invention.

[0023] Figure 5 It is an explanatory diagram for explaining a reheater in one embodiment of the present invention.

[0024] Figure 6 This is an explanatory diagram for explaining the second heat medium circulation circuit.

[0025] Figure 7 This is a schematic structural diagram schematically showing a part of the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0026] Figure 8 This is a schematic structural diagram schematically showing a part of the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0028] For example, descriptions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" that indicate a relative or absolute configuration not only indicate such a strict configuration, but also indicate a state of relative displacement at an angle or distance with a tolerance or a degree that can achieve the same function.

[0029] For example, descriptions such as “same”, “equal”, and “homogeneous” indicating a state in which things are equal indicate not only a state of being strictly equal but also a state in which there is a tolerance or a difference to the extent that the same function can be obtained.

[0030] For example, descriptions indicating shapes such as a quadrilateral and a cylinder not only indicate shapes such as a quadrilateral and a cylinder in a strict geometric sense, but also indicate shapes including concave and convex portions, chamfered portions, etc. within a range that can produce the same effect.

[0031] On the other hand, descriptions such as “having”, “including”, or “having” a constituent element do not mean exclusive descriptions excluding the presence of other constituent elements.

[0032] In addition, the same symbols are used to designate the same structures and the description thereof may be omitted.

[0033] Figure 1 This is a schematic structural diagram schematically showing the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0034] like Figure 1As shown, the power recovery system 1 according to some embodiments recovers power from liquefied gas supplied from a liquefied gas storage device (a liquefied gas tank in the example shown) 31 storing liquefied gas. In addition, the power recovery system 1 may also recover power from gas after liquefied gas is vaporized. The power recovery system 1 includes at least a first turbine 2, which is driven by gas after liquefied gas is vaporized supplied from the liquefied gas storage device 31.

[0035] (Power Equipment)

[0036] The power recovery system 1 is included in the power device 10. Figure 1 As shown, the power device 10 has a liquefied gas supply system 3, a heat medium circulation line 4 and a gas combustion system 5. In the illustrated embodiment, the power device 10 including the power recovery system 1 is mounted on a floating structure 100 on the water. The floating structure 100 on the water is a structure that can float on the water. The floating structure 100 on the water includes a ship 100A and a floating body 100B without a propulsion device. The ship A has a propulsion device configured to drive a propeller or other propeller, and can travel by itself by driving the propulsion device. In addition, in other embodiments, the power device 10 including the power recovery system 1 can also be at least partially set on land.

[0037] (Liquefied gas supply system)

[0038] like Figure 1 As shown, the liquefied gas supply system 3 includes: the above-mentioned liquefied gas storage device 31; a liquefied gas supply line 32, which is used to guide the liquefied gas and the gas after the liquefied gas is gasified supplied from the liquefied gas storage device 31; a liquefied gas pump 33 arranged on the liquefied gas supply line 32; and the above-mentioned first turbine 2 arranged on the liquefied gas supply line 32.

[0039] The liquefied gas supply line 32 has a flow path through which a fluid (liquefied gas, gas after liquefied gas is vaporized) can flow. One side 321 of the liquefied gas supply line 32 is connected to the liquefied gas storage device 31, and the other side 322 is connected to the supply destination 34 of the gas after liquefied gas is vaporized. The gas supply destination 34 can be set inside or outside the power equipment 10 (floating structure 100). By driving the liquefied gas pump 33, the liquefied gas stored in the liquefied gas storage device 31 is transported to the liquefied gas supply line 32, and flows along the liquefied gas supply line 32 from the upstream side (one side 321) to the downstream side (the other side 322).

[0040] In the illustrated embodiment, the liquefied gas supply system 3 further includes a first heat exchanger 11 provided on the upstream side of the first turbine 2 of the liquefied gas supply line 32 and a second heat exchanger 12 provided on the downstream side of the first turbine 2 of the liquefied gas supply line 32. In the illustrated embodiment, a liquefied gas pump 33 is provided on the upstream side of the first heat exchanger 11 of the liquefied gas supply line 32.

[0041] The heat medium circulation circuit 4 includes a first heat medium circulation circuit 4A configured to circulate a first heat medium for heat exchange with the liquefied gas supplied from the liquefied gas storage device 31. The first heat medium circulation circuit 4A includes at least a first heat medium circulation circuit 41 for circulating the first heat medium. The first heat medium circulation circuit 41 has a flow path through which a fluid (first heat medium) can flow.

[0042] In the following, liquefied natural gas (LNG) is used as a specific example of the liquefied gas stored in the liquefied gas storage device 31, and propane is used as a specific example of the heat medium flowing in the heat medium circulation line 4. However, the present invention can also be applied to the case where liquefied gas other than liquefied natural gas (liquefied petroleum gas, liquid hydrogen, etc.) is used as the liquefied gas stored in the liquefied gas storage device 31. In addition, it can also be applied to the case where a heat medium other than propane is used as the heat medium flowing in the heat medium circulation line 4.

[0043] The first heat exchanger 11 is configured to perform heat exchange between the liquefied gas flowing in the liquefied gas supply line 32 and the first heat medium flowing in the first heat medium circulation line 41. Figure 1 In the illustrated embodiment, the first heat exchanger 11 includes a first heat exchange section 111 through which the liquefied gas provided in the liquefied gas supply line 32 flows, and a second heat exchange section 112 through which the first heat medium provided in the first heat medium circulation line 41 flows. The temperature of the first heat medium flowing in the second heat exchange section 112 is higher than the temperature of the liquefied gas flowing in the first heat exchange section 111. Heat exchange is performed between the first heat exchange section 111 and the second heat exchange section 112, the liquefied gas flowing in the first heat exchange section 111 is heated, and the first heat medium flowing in the second heat exchange section 112 is cooled. The liquefied gas flowing in the liquefied gas supply line 32 is heated in the first heat exchange section 111 of the first heat exchanger 11 and is gasified.

[0044] In the illustrated embodiment, the first heat medium circulation circuit 4A is configured to circulate the first heat medium under an organic Rankine cycle. The first heat medium circulation circuit 4A shares the liquefied gas supply system 3 and the first heat exchanger 11. The first heat medium circulation circuit 4A includes: the above-mentioned first heat medium circulation circuit 41; the above-mentioned first heat exchanger 11; a circulation pump 42 for the first heat medium, which is arranged on the downstream side of the second heat exchange section 112 (first heat exchanger 11) of the first heat medium circulation circuit 41; a third heat exchanger 43, which is arranged on the downstream side of the circulation pump 42 of the first heat medium circulation circuit 41; and a turbine 7A for the first heat medium, which is arranged on the downstream side of the third heat exchanger 43 of the first heat medium circulation circuit 41.

[0045] By driving the circulation pump 42, the first heat medium circulates in the first heat medium circulation line 41. The third heat exchanger 43 is configured to perform heat exchange between the first heat medium flowing in the first heat medium circulation line 41 and seawater. In addition, the third heat exchanger 43 may also be configured to perform heat exchange between the first heat medium and seawater indirectly via an intermediate heat medium. Figure 1 In the illustrated embodiment, the third heat exchanger 43 includes a first heat medium side heat exchange portion 431 through which the first heat medium provided in the first heat medium circulation line 41 flows, and a seawater side heat exchange portion 432 through which seawater obtained from the outside of the power device 10 flows. The first heat medium flowing in the first heat medium side heat exchange portion 431 is lower in temperature than the seawater flowing in the seawater side heat exchange portion 432. Heat exchange is performed between the first heat medium side heat exchange portion 431 and the seawater side heat exchange portion 432, and the first heat medium flowing in the first heat medium side heat exchange portion 431 is heated.

[0046] (Turbine for the first heat medium)

[0047] like Figure 1 As shown, the turbine 7A for the first heat medium includes: a rotating shaft 71A; a turbine blade 72A mounted on the rotating shaft 71A; a housing 73A, which accommodates the rotating shaft 71A and the turbine blade 72A so that they can rotate; and a shaft seal 74A, which seals the rotating shaft 71A and the housing 73A. At least one side of the axial direction of the rotating shaft 71A protrudes to the outside of the housing 73A. The housing 73A is formed with a first heat medium inlet 75A and a first heat medium outlet 76A. The first heat medium inlet 75A is used to introduce the first heat medium into the interior of the housing 73A, and the first heat medium outlet 76A discharges the first heat medium that has passed through the turbine blade 72A to the outside of the housing 73A.

[0048] The turbine 7A for the first heat medium is configured to use the first heat medium as a working fluid and be driven by the working fluid. The first heat medium, which is pressurized by the circulation pump 42 and heated by the third heat exchanger 43 (the first heat medium side heat exchange unit 431), is delivered to the turbine 7A for the first heat medium. The turbine blade 72A is rotated by the energy of the first heat medium introduced into the interior of the housing 73A through the first heat medium introduction port 75A. The first heat medium that has passed through the turbine blade 72A is discharged to the outside of the housing 73A through the first heat medium discharge port 76A.

[0049] The power recovery system 1 is configured to recover the rotational force of the turbine blades 72A as power. In the illustrated embodiment, the power recovery system 1 further includes a generator 44 for the first heat medium, and the generator 44 is configured to generate electricity by driving the turbine 7A. The generator 44 is mechanically connected to the rotating shaft 71A and is configured to convert the rotational force of the turbine blades 72A into electricity. In addition, in other embodiments, the power recovery system 1 may not convert the rotational force of the turbine blades 72A into electricity, but directly recover power through a power transmission device (such as a coupling, a belt, a pulley, etc.).

[0050] (First Turbine)

[0051] like Figure 1 As shown, the first turbine 2 includes: a rotating shaft 21; a turbine blade 22 mounted on the rotating shaft 21; a housing 23, the housing 23 rotatably accommodating the rotating shaft 21 and the turbine blade 22; and a shaft seal 24, the shaft seal 24 sealing the rotating shaft 21 and the housing 23. At least one side of the axial direction of the rotating shaft 21 protrudes to the outside of the housing 23. The housing 23 is formed with a gas inlet 25 and a gas outlet 26. The gas inlet 25 is used to introduce gas after gasification of liquefied gas supplied from the liquefied gas storage device 31 into the interior of the housing 23, and the gas outlet 26 is used to discharge the gas passing through the turbine blade 22 to the outside of the housing 23.

[0052] The first turbine 2 is configured to use gas obtained by vaporizing liquefied gas as a working fluid and to be driven by the working fluid. The gas pressurized by the liquefied gas pump 33 and vaporized by the first heat exchanger 11 is delivered to the first turbine 2. The turbine blades 22 are rotated by the energy of the gas introduced into the interior of the housing 23 through the gas inlet 25. The gas that has passed through the turbine blades 22 is discharged to the outside of the housing 23 through the gas outlet 26.

[0053] The power recovery system 1 is configured to recover the rotational force of the turbine blades 22 as power. In the illustrated embodiment, the power recovery system 1 further includes a generator 13, which is configured to generate electricity by driving the first turbine 2. The generator 13 is mechanically connected to the rotating shaft 21 and is configured to convert the rotational force of the turbine blades 22 into electricity. In addition, in other embodiments, the power recovery system 1 may not convert the rotational force of the turbine blades 22 into electricity, but directly recover power through a power transmission device (such as a coupling, a belt, a pulley, etc.).

[0054] The gas exhausted from the first turbine 2 passes through the first turbine 2, whereby its temperature is reduced. The second heat exchanger 12 is configured to perform heat exchange between the gas exhausted from the first turbine 2 and a heat medium having a higher temperature than the gas. Figure 1 In the embodiment shown, a third heat exchange section 121 and a fourth heat exchange section 122 are included. The third heat exchange section 121 is used to flow gas after liquefied gas is vaporized on the downstream side of the first turbine 2 provided on the liquefied gas supply line 32, and the fourth heat exchange section 122 is used to flow heat medium having a higher temperature than the gas flowing in the third heat exchange section 121. Figure 1 In the embodiment shown, the heat medium for heat exchange in the second heat exchanger 12 (fourth heat exchange section 122) is composed of seawater. Heat exchange is performed between the third heat exchange section 121 and the fourth heat exchange section 122, and the gas flowing in the third heat exchange section 121 is heated. The gas heated and heated in the second heat exchanger 12 is transported to the gas supply destination 34.

[0055] (Power Recovery System)

[0056] like Figure 1 As shown, the power recovery system 1 involved in several embodiments comprises: the above-mentioned first turbine 2, which is driven by gas after liquefied gas supplied from the liquefied gas storage device 31; a first leakage gas inlet pipe 14, which is used to guide the gas (first leakage gas) leaking from the shaft seal portion 24 of the first turbine 2; and a gas combustion device 51, which causes the gas guided by the first leakage gas inlet pipe 14 to burn.

[0057] The gas combustion device 51 has: a gas inlet port 52, which is used to introduce gas fuel; an air inlet port 53, which is used to introduce air; a combustion section 54, which is configured to burn the gas fuel introduced from the gas inlet port 52 and the air introduced from the air inlet port 53; and an exhaust gas exhaust port 55, which is used to discharge the exhaust gas generated by the combustion in the combustion section 54 to the outside of the gas combustion device 51.

[0058] In the illustrated embodiment, one side 141 of the first leakage gas inlet pipe 14 is arranged on the outer side of the shaft seal portion 24 of the first turbine 2 and adjacent to the shaft seal portion 24, and the other side 142 of the first leakage gas inlet pipe 14 is connected to the gas inlet port 52 for introducing the gas fuel of the gas combustion device 51. In this case, the first leakage gas is guided from the one side 141 of the first leakage gas inlet pipe 14 to the inside of the first leakage gas inlet pipe 14, and after flowing through the first leakage gas inlet pipe 14 from the one side 141 toward the other side 142, it is guided to the combustion portion 54 of the gas combustion device 51 through the gas inlet port 52. The first leakage gas guided to the combustion portion 54 is combusted by the combustion portion 54. Figure 1 In the illustrated embodiment, the power recovery system 1 further includes a blower 15 installed in the middle of the first leakage gas introduction pipe 14. The blower 15 has an impeller (not shown) and is configured to transport the first leakage gas from one side 141 of the first leakage gas introduction pipe 14 to the other side 142 by the rotational motion of the impeller. In addition, the power recovery system 1 may also use the suction force generated by the blower 15 to suck the first leakage gas into the first leakage gas introduction pipe 14. In this case, the above-mentioned "position adjacent to the shaft seal portion 24" includes a position where the first leakage gas can be sucked into the first leakage gas introduction pipe 14 by the suction force generated by the blower 15.

[0059] According to the above-mentioned structure, the power recovery system 1 can guide the gas (first leakage gas) leaking from the shaft seal portion 24 of the first turbine 2 to the gas combustion device 51 through the first leakage gas introduction pipe 14, and perform combustion treatment in the gas combustion device 51. The power recovery system 1 can suppress the first leakage gas from flowing into the atmosphere by performing combustion treatment on the first leakage gas by the gas combustion device 51. Therefore, even if the power recovery system 1 does not set the sealing performance of the shaft seal portion 24 of the first turbine 2 to high performance as in the past, it is possible to suppress the gas from the first turbine 2 to leak into the atmosphere. In addition, the power recovery system 1 can use the first leakage gas as fuel for the gas combustion device 51 by performing combustion treatment on the first leakage gas by the gas combustion device 51.

[0060] In addition, according to the above-mentioned structure, the power recovery system 1 does not need to set the sealing performance of the shaft seal portion 24 of the first turbine 2 to high performance as in the past, so the structure of the shaft seal portion 24 of the first turbine 2 can be made simpler than in the past. As a result, the complexity and high cost of the structure of the first turbine 2 can be suppressed, and the high cost of the power recovery system 1 can be suppressed.

[0061] (Evaporation gas inlet pipe)

[0062] Figure 2This is a schematic structural diagram schematically showing the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0063] In some embodiments, such as Figure 2 As shown, the power recovery system 1 further includes a boil-off gas introduction pipe 16 for guiding boil-off gas gasified in the liquefied gas storage device 31 to the gas combustion device 51 .

[0064] In the illustrated embodiment, one side 161 of the boil-off gas introduction pipe 16 is connected to the liquefied gas storage device 31, and the other side 162 of the boil-off gas introduction pipe 16 merges with the first leaked gas introduction pipe 14. The boil-off gas vaporized by the liquefied gas storage device 31 is pressurized by the liquefied gas storage device 31, and therefore flows toward the downstream side (the gas combustion device 51 side) due to its own pressure. The boil-off gas is guided from the one side 161 of the boil-off gas introduction pipe 16 to the inside of the boil-off gas introduction pipe 16, and after flowing from the one side 161 of the boil-off gas introduction pipe 16 to the other side 162, it is guided to the combustion section 54 of the gas combustion device 51 through the gas introduction port 52. The boil-off gas guided to the combustion section 54 is combusted by the combustion section 54.

[0065] According to the above-mentioned structure, the power recovery system can guide the boil-off gas gasified by the liquefied gas storage device 31 to the gas combustion device 51 through the boil-off gas introduction pipe 16, and the gas combustion device 51 performs combustion treatment. Therefore, the power recovery system 1 can use the boil-off gas as fuel for the gas combustion device 51 by performing combustion treatment on the boil-off gas by the gas combustion device 51.

[0066] According to the above configuration, the power recovery system 1 can burn the first leaked gas and the boil-off gas using the common gas combustion device 51. The power recovery system 1 can suppress the increase in size and cost of the power recovery system 1 by using the common gas combustion device 51.

[0067] In some embodiments, such as Figure 2 As shown, one side 161 of the boil-off gas introduction pipe 16 is connected to the liquefied gas storage device 31 , and the other side 162 thereof merges with the first leaked gas introduction pipe 14 .

[0068] According to the above structure, the power recovery system 1 uses the downstream side of the confluence portion 143 of the first leakage gas introduction pipe 14 and the evaporated gas introduction pipe 16 as the common portion 144, and can guide the first leakage gas and the evaporated gas to the gas combustion device 51 through the common portion 144. In this case, the gas combustion device 51 does not need to be provided with the gas introduction port 52 for introducing the first leakage gas and the evaporated gas, respectively, so that the complexity and cost of the structure of the gas combustion device 51 can be suppressed.

[0069] In some other embodiments, the other side 162 of the boil-off gas introduction pipe 16 may be connected to a gas introduction port for boil-off gas provided in the gas combustion device 51 .

[0070] (Air seal of the first turbine)

[0071] Figure 3 This is a schematic structural diagram schematically showing the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0072] In some embodiments, such as Figure 3 As shown, the above-mentioned power recovery system 1 also includes: a first compressor 56, which is configured to compress air; a first compressed air inlet pipe 57, which is used to introduce the compressed air compressed by the first compressor 56 into the gas combustion device 51; and a first compressed air supply pipe 17, which is branched from the first compressed air inlet pipe 57 and is used to guide a part of the compressed air to the shaft seal portion 24 of the first turbine 2.

[0073] One side 572 of the first compressed air introduction pipe 57 is connected to the first compressor 56, and the other side 571 is connected to the air introduction port 53 of the gas combustion device 51. One side 171 of the first compressed air supply pipe 17 is connected to the first compressed air introduction pipe 57 at a branch portion 573 of the first compressed air introduction pipe 57 provided on the downstream side of the first compressor 56 (on the side of the gas introduction port 52).

[0074] In the illustrated embodiment, the gas combustion system 5 includes: the gas combustion device 51 described above; the first compressor 56 described above; the first compressed air introduction pipe 57 described above; an exhaust gas introduction pipe 59 for introducing the exhaust gas discharged from the gas combustion device 51 into the exhaust gas turbine 58; and the exhaust gas turbine 58 described above, which is configured to be driven by the exhaust gas introduced by the exhaust gas introduction pipe 59. The first compressor 56 includes a compressor (turbocharged compressor) 56A and an electric compressor 56B, and the compressor 56A has a rotor mechanically connected to the drive shaft of the exhaust gas turbine 58. In addition, in other embodiments, the first compressor 56 may include either the compressor 56A or the electric compressor 56B.

[0075] According to the above-mentioned structure, the power recovery system 1 guides a part of the compressed air compressed by the first compressor 56 to the shaft seal portion 24 of the first turbine 2 through the first compressed air supply pipe 17 and uses it as an air seal, thereby being able to suppress the gas (first leakage gas) from leaking from the shaft seal portion 24 of the first turbine 2. In addition, the power recovery system 1 uses the compressed air compressed by the first compressor 56 as an air seal, and can guide the first leakage gas to the gas combustion device 51 in a state of being pre-mixed with compressed air, thereby being able to improve the combustion efficiency of the gas combustion device 51.

[0076] Figure 4 This is a schematic cross-sectional view schematically showing a cross section of a first turbine along the axis of a rotating shaft in one embodiment of the present invention.

[0077] In some embodiments, such as Figure 4 As shown, the shaft seal portion 24 of the above-mentioned first turbine 2 includes: the rotating shaft 21 of the first turbine 2; a downstream side seal portion 24B, which seals the casing 23 of the first turbine 2; and an upstream side seal portion 24A, which seals the rotating shaft 21 and the casing 23 on the upstream side of the downstream side seal portion 24B. The first compressed air supply pipe 17 is connected to the space 231 formed between the downstream side seal portion 24B and the upstream side seal portion 24A. Here, the "upstream side" is based on the direction of leakage of the first leakage gas. Figure 4 In the diagram, the first leaked gas leaks from one side (the left side in the diagram) to the other side (the right side in the diagram) in the axial direction of the rotating shaft 21 , and therefore, the one side is the upstream side and the other side is the downstream side.

[0078] In the illustrated embodiment, the housing 23 includes: an upstream first annular portion 232, the inner circumference of which is sealed by an upstream sealing portion 24A; a downstream second annular portion 233, the inner circumference of which is sealed by a downstream sealing portion 24B; and an annular axial direction extending portion 234, which extends from the first annular portion 232 to the other side (downstream side) in the axial direction of the rotating shaft 21 and is connected to the second annular portion 233. The above-mentioned space 231 is formed on the inner circumference of the axial direction extending portion 234.

[0079] In the illustrated embodiment, the housing 23 is formed with a through hole 235 that penetrates in a manner that connects the axial extension portion 234 to the inside and outside, and the through hole 235 is connected to the other side 172 of the first compressed air supply pipe 17 from the outer peripheral side. The compressed air flowing in the first compressed air inlet pipe 57 is pressurized by the first compressor 56, so a part of it flows to the downstream side (space 231 side) due to its own pressure. A part of the compressed air flowing in the first compressed air inlet pipe 57 is guided from one side 171 of the first compressed air supply pipe 17 to the inside of the first compressed air supply pipe 17, flows from one side 171 of the first compressed air supply pipe 17 toward the other side 172, and then is guided to the space 231. By introducing the compressed air into the space 231, the fluid (including the first leakage gas and the compressed air) inside the space 231 is pressurized.

[0080] According to the above-mentioned structure, the power recovery system 1 can guide a part of the compressed air compressed by the first compressor 56 to the space 231 formed between the downstream side seal portion 24B and the upstream side seal portion 24A of the first turbine 2 through the first compressed air supply pipe 17. As a result, compared with the case where the compressed air is not introduced into the above-mentioned space 231, the pressure difference between the upstream side of the upstream side seal portion 24A and the downstream side of the upstream side seal portion 24A (space 231) can be reduced, so that the gas can be suppressed from leaking to the downstream side of the upstream side seal portion 24A. As a result, the gas (first leakage gas) can be suppressed from leaking from the shaft seal portion 24 of the first turbine 2.

[0081] like Figure 4As shown, in some embodiments, the upstream side seal portion 24A and the downstream side seal portion 24B are composed of a labyrinth seal 24C. As described above, the power recovery system 1 performs combustion treatment on the first leakage gas by the gas combustion device 51, thereby, even if the sealing performance of the shaft seal portion 24 of the first turbine 2 is not set to high performance as in the past, it is possible to suppress the gas from leaking from the first turbine 2 to the atmosphere. According to the above-mentioned structure, by using the labyrinth seal 24C for sealing in the shaft seal portion 24 (upstream side seal portion 24A and downstream side seal portion 24B) of the first turbine 2, it is possible to fully suppress the gas from leaking from the first turbine 2 to the atmosphere. In addition, by using the labyrinth seal 24C with a simple structure for sealing in the shaft seal portion 24 of the first turbine 2, it is possible to suppress the complexity and high cost of the structure of the first turbine 2, and thus suppress the high cost of the power recovery system 1.

[0082] Figure 5 It is an explanatory diagram for explaining a reheater in one embodiment of the present invention.

[0083] In some embodiments, such as Figure 5 As shown, the power recovery system 1 further includes an air extraction pipe 61, which extracts gas from the first turbine 2 and returns the gas to the downstream side of the gas extraction position P1 in the first turbine 2, and a reheater 62, which is configured to heat the gas flowing through the air extraction pipe 61. In the illustrated embodiment, the gas extracted by the air extraction pipe 61 is delivered to the turbine blade 22 on the downstream side of the air extraction position P1.

[0084] According to the above structure, a part of the gas expanded in the first turbine 2 is returned to the downstream side of the extraction position P1 in the first turbine 2 through the extraction pipe 61 after being extracted by the extraction pipe 61 and heated by the reheater 62. That is, the above-mentioned power recovery system 1 adopts a reheat cycle. In this case, the power recovery system 1 can suppress the increase of the steam humidity at the end of expansion (near the last stage) in the first turbine 2 by heating the gas using the reheater 62, thereby suppressing the corrosion of the turbine blades 22 near the last stage, and achieving an improvement in the thermal efficiency of the first turbine 2.

[0085] In some embodiments, such as Figure 5 As shown, the reheater 62 includes a heat exchanger 62A configured to perform heat exchange between the gas flowing in the gas extraction pipe 61 and a heat medium (first heat medium) that exchanges heat with the liquefied gas supplied from the liquefied gas storage device 31 .

[0086] In the illustrated embodiment, the heat exchanger 62A includes a fifth heat exchange section 621 through which the first heat medium provided in the first heat medium circulation line 41 flows, and a sixth heat exchange section 622 provided in the exhaust pipe 61. The temperature of the first heat medium flowing in the fifth heat exchange section 621 is higher than the temperature of the gas after the liquefied gas flows in the sixth heat exchange section 622. Heat exchange is performed between the fifth heat exchange section 621 and the sixth heat exchange section 622, and the gas flowing in the sixth heat exchange section 622 is heated. Figure 5 In the illustrated embodiment, the heat exchanger 62A and the first heat exchanger 11 are housed in the same casing.

[0087] According to the above structure, the heat exchanger 62A is used to perform heat exchange between the gas (exhaust gas) extracted from the first turbine 2 and flowing in the exhaust pipe 61 and the first heat medium, and the exhaust gas is heated. In this case, the structure of the heat exchanger 62A (reheater 62) can be simplified, and the first heat medium can be used as a heat source for the exhaust gas in the heat exchanger 62A. By using the first heat medium as a heat source for the exhaust gas in the heat exchanger 62A, condensation in the condensation process of the first heat medium is promoted, thereby achieving an improvement in the thermal efficiency of the second turbine 7 (turbine 7A).

[0088] In addition, in other embodiments, the reheater 62 may be a heater that heats the gas flowing in the air extraction pipe 61. In addition, the reheater 62 may be a heat exchanger configured to perform heat exchange between the gas flowing in the air extraction pipe 61 and seawater, or a heat exchanger configured to perform heat exchange between the gas flowing in the air extraction pipe 61 and a second heat medium described later.

[0089] Figure 6 This is an explanatory diagram for explaining the second heat medium circulation circuit.

[0090] The heat medium circulation circuit 4 includes at least one of the first heat medium circulation circuit 4A and the second heat medium circulation circuit 4B configured to circulate a heat medium (second heat medium) that exchanges heat with the gas exhausted from the first turbine 2 .

[0091] like Figure 6As shown, the second heat medium circulation line 4B is configured to circulate the second heat medium under the organic Rankine cycle. The second heat medium circulation line 4B shares the liquefied gas supply system 3 and the second heat exchanger 12. The second heat medium circulation line 4B includes: a second heat medium circulation line 45, which is used to circulate the second heat medium; the above-mentioned second heat exchanger 12; a circulation pump 46 for the second heat medium, which is arranged on the downstream side of the fourth heat exchange part 122 (the second heat exchanger 12) of the second heat medium circulation line 45; a fourth heat exchanger 47, which is arranged on the downstream side of the circulation pump 46 of the circulation line 45 of the second heat medium; and a turbine 7B for the second heat medium, which is arranged on the downstream side of the fourth heat exchanger 47 of the second heat medium circulation line 45. The second heat medium circulation line 45 has a flow path that can allow the fluid (second heat medium) to flow.

[0092] By driving the circulation pump 46, the second heat medium circulates in the second heat medium circulation line 45. The fourth heat exchanger 47 is configured to perform heat exchange between the second heat medium flowing in the second heat medium circulation line 45 and seawater. In addition, the fourth heat exchanger 47 may also be configured to perform heat exchange between the second heat medium and seawater indirectly via an intermediate heat medium. Figure 6 In the illustrated embodiment, the fourth heat exchanger 47 includes a second heat medium side heat exchange portion 471 through which the second heat medium provided in the second heat medium circulation line 45 flows, and a seawater side heat exchange portion 472 through which seawater obtained from the outside of the power device 10 flows. The second heat medium flowing in the second heat medium side heat exchange portion 471 is lower in temperature than the seawater flowing in the seawater side heat exchange portion 472. Heat exchange is performed between the second heat medium side heat exchange portion 471 and the seawater side heat exchange portion 472, and the second heat medium flowing in the second heat medium side heat exchange portion 471 is heated.

[0093] (Turbine for the second heat medium)

[0094] The second turbine 7 includes at least one of the turbine 7A for the first heat medium and the turbine 7B for the second heat medium. Figure 6As shown, the turbine 7B includes: a rotating shaft 71B; a turbine blade 72B mounted on the rotating shaft 71B; a housing 73B, which accommodates the rotating shaft 71B and the turbine blade 72B so that they can rotate; and a shaft seal 74B, which seals the rotating shaft 71B and the housing 73B. At least one side of the axial direction of the rotating shaft 71B protrudes to the outside of the housing 73B. The housing 73B is formed with a second heat medium inlet 75B and a second heat medium outlet 76B. The second heat medium inlet 75B is used to introduce the second heat medium into the interior of the housing 73B, and the second heat medium outlet 76B is used to discharge the second heat medium that has passed through the turbine blade 72B to the outside of the housing 73B.

[0095] The turbine 7B for the second heat medium is configured to use the second heat medium as a working fluid and be driven by the working fluid. The second heat medium, which is pressurized by the circulation pump 46 and heated by the fourth heat exchanger 47 (second heat medium side heat exchange unit 471), is delivered to the turbine 7B for the second heat medium. The turbine blade 72B is rotated by the energy of the second heat medium introduced into the inside of the housing 73B through the second heat medium introduction port 75B. The second heat medium that has passed through the turbine blade 72B is discharged to the outside of the housing 73B through the second heat medium discharge port 76B.

[0096] The power recovery system 1 is configured to recover the rotational force of the turbine blades 72B as power. In the illustrated embodiment, the power recovery system 1 further includes a generator 48 for the second heat medium, and the generator 48 is configured to generate electricity by driving the turbine 7B. The generator 48 is mechanically connected to the rotating shaft 71B and is configured to convert the rotational force of the turbine blades 72B into electricity. In addition, in other embodiments, the power recovery system 1 may not convert the rotational force of the turbine blades 72B into electricity, but directly recover power through a power transmission device (such as a coupling, a belt, a pulley, etc.).

[0097] Figure 7 and Figure 8 Each of them is a schematic structural diagram schematically showing a part of the structure of a floating structure on water equipped with a power recovery system according to an embodiment of the present invention.

[0098] In some embodiments, such as Figure 7 and Figure 8As shown, the power recovery system 1 further comprises: a heat medium circulation circuit 4, which is configured to circulate a heat medium for heat exchange with the liquefied gas supplied from the liquefied gas storage device 31 or the gas discharged from the first turbine 2, and includes a second turbine 7 that uses the heat medium as a working fluid; and a second leakage gas inlet pipe 18, which is used to guide the working fluid leaking from the shaft seal sealing portion 74 (74A, 74B) of the second turbine 7 to the gas combustion device 51.

[0099] exist Figure 7 In the embodiment shown, the heat medium circulation circuit 4 includes a first heat medium circulation circuit 4A having the turbine 7A described above. In the present embodiment, the first heat medium is combustible. The second leakage gas introduction pipe 18 includes a leakage gas introduction pipe 18A for guiding the working fluid (first heat medium) leaking from the shaft seal seal portion 74A of the turbine 7A for the first heat medium described above to the gas combustion device 51.

[0100] exist Figure 7 In the illustrated embodiment, one side 181 of the leakage gas introduction pipe 18A is arranged outside the shaft seal portion 74A and adjacent to the shaft seal portion 74A (74), and the other side 182 of the leakage gas introduction pipe 18A is connected to the upstream side (one side 141) of the blower 15 of the first leakage gas introduction pipe 14. The working fluid (first heat medium) leaking from the shaft seal portion 74A is guided to the combustion portion 54 through the leakage gas introduction pipe 18A, the first leakage gas introduction pipe 14, and the gas introduction port 52. The combustible first heat medium guided to the combustion portion 54 is combusted by the combustion portion 54. In addition, the power recovery system 1 may use the suction force generated by the blower 15 to suck the first heat medium leaking from the shaft seal portion 74A into the leakage gas introduction pipe 18A.

[0101] exist Figure 8 In the embodiment shown, the heat medium circulation circuit 4 includes a second heat medium circulation circuit 4B having the above-mentioned turbine 7B. In this embodiment, the second heat medium is combustible. Figure 8 In the embodiment shown, the heat medium for heat exchange in the second heat exchanger 12 (fourth heat exchange unit 122) is composed of propane. The second leakage gas introduction pipe 18 includes a leakage gas introduction pipe 18B for the second heat medium, which is used to guide the working fluid (second heat medium) leaking from the shaft seal seal portion 74B of the turbine 7B for the second heat medium to the gas combustion device 51.

[0102] exist Figure 8In the illustrated embodiment, one side 183 of the leakage gas introduction pipe 18B is arranged outside the shaft seal portion 74B and adjacent to the shaft seal portion 74B (74), and the other side 184 of the leakage gas introduction pipe 18B is connected to the upstream side (one side 141) of the blower 15 of the first leakage gas introduction pipe 14. The working fluid (second heat medium) leaking from the shaft seal portion 74B is guided to the combustion portion 54 through the leakage gas introduction pipe 18B, the first leakage gas introduction pipe 14, and the gas introduction port 52. The combustible second heat medium guided to the combustion portion 54 is combusted by the combustion portion 54. In addition, the power recovery system 1 may use the suction force generated by the blower 15 to suck the second heat medium leaking from the shaft seal portion 74B into the leakage gas introduction pipe 18B. In this case, the above-mentioned "position adjacent to the shaft seal portion 74 (74A, 74B)" includes a position where the gas (second leakage gas) leaking from the shaft seal portion 74 of the second turbine 7 can be sucked into the second leakage gas introduction pipe 18 (18A, 18B) by the suction force generated by the blower 15. In addition, the power recovery system 1 may also include both the leakage gas introduction pipe 18A and the leakage gas introduction pipe 18B.

[0103] According to the above-mentioned structure, the power recovery system 1 can guide the gas (second leakage gas) leaking from the shaft seal portion 74 of the second turbine 7 of the heat medium circulation line 4 to the gas combustion device 51 through the second leakage gas introduction pipe 18, and the gas combustion device 51 performs combustion treatment. The power recovery system 1 can suppress the second leakage gas from flowing into the atmosphere by performing combustion treatment on the second leakage gas by the gas combustion device 51. Therefore, even if the power recovery system 1 does not set the sealing performance of the shaft seal portion 74 of the second turbine 7 to high performance as in the past, it is possible to suppress the gas from leaking from the second turbine 7 to the atmosphere. In addition, the power recovery system 1 can use the second leakage gas as fuel for the gas combustion device 51 by performing combustion treatment on the second leakage gas by the gas combustion device 51.

[0104] In addition, according to the above-mentioned structure, the power recovery system 1 does not need to set the sealing performance of the shaft seal portion 74 of the second turbine 7 to high performance as in the past, so the structure of the shaft seal portion 74 of the second turbine 7 can be made simpler than in the past. As a result, the complexity and high cost of the structure of the second turbine 7 can be suppressed, and the high cost of the power recovery system 1 can be suppressed.

[0105] In some embodiments, such as Figure 7 and Figure 8As shown, the above-mentioned power recovery system 1 comprises: a second compressor 81, which is configured to compress air; a second compressed air inlet pipe 82, which is used to introduce the compressed air compressed by the second compressor 81 into the gas combustion device 51; and a second compressed air supply pipe 83, which is branched from the second compressed air inlet pipe 82 and is used to guide a part of the compressed air compressed by the second compressor 81 to the shaft seal portion 74 (74A, 74B) of the second turbine 7.

[0106] exist Figure 7 and in Figure 8 In the illustrated embodiment, the second compressor 81 is shared with the first compressor 56, and the second compressed air inlet pipe 82 is shared with the first compressed air inlet pipe 57. In this case, the number of compressors and compressed air inlet pipes can be reduced, thereby suppressing the enlargement of the power recovery system 1. In addition, in other embodiments, the second compressor 81 and the second compressed air inlet pipe 82 may be separately provided from the first compressor 56 and the first compressed air inlet pipe 57.

[0107] In the illustrated embodiment, the second compressed air supply pipe 83 is connected to the second compressed air introduction pipe 82 through a branch portion 821 provided on the downstream side (gas introduction port 52 side) of the second compressor 81 in the second compressed air introduction pipe 82. The second compressed air supply pipe 83 is shared with the first compressed air supply pipe 17 on the upstream side of the confluence portion 831 with the first compressed air supply pipe 17.

[0108] exist Figure 7 In the embodiment shown, the second compressed air supply pipe 83 includes a compressed air supply pipe 83A for the first heat medium, and the compressed air supply pipe 83A is configured to guide the compressed air to the shaft seal portion 74A of the turbine 7A for the first heat medium. In this case, the compressed air guided to the shaft seal portion 74A through the compressed air supply pipe 83A (the second compressed air supply pipe 83) is used as an air seal, thereby preventing the first heat medium from leaking from the shaft seal portion 74A.

[0109] exist Figure 8In the embodiment shown, the second compressed air supply pipe 83 includes a compressed air supply pipe 83B for the second heat medium, and the compressed air supply pipe 83B is configured to guide the compressed air to the shaft seal portion 74B of the turbine 7B for the second heat medium. In this case, the compressed air guided to the shaft seal portion 74B through the compressed air supply pipe 83B (the second compressed air supply pipe 83) is used as an air seal, thereby suppressing the leakage of the second heat medium from the shaft seal portion 74B. In addition, the power recovery system 1 may also include both the compressed air supply pipe 83A and the compressed air supply pipe 83B.

[0110] According to the above-mentioned structure, the power recovery system 1 guides a part of the compressed air compressed by the second compressor 81 to the shaft seal portion 74 of the second turbine 7 through the second compressed air supply pipe 83 and uses it as an air seal, thereby suppressing the gas (second leakage gas) from leaking from the shaft seal portion 74 of the second turbine 7. In addition, the power recovery system 1 uses the compressed air compressed by the second compressor 81 as an air seal, and can guide the second leakage gas to the gas combustion device 51 in a state of being pre-mixed with compressed air, thereby improving the combustion efficiency of the gas combustion device 51.

[0111] like Figure 1 to Figure 3 , Figures 5 to 8 As shown, the floating structures 100 according to the embodiments are equipped with the power recovery system 1. In this case, the power recovery system 1 can suppress the gas leakage of the first turbine 2 driven by the gas after the liquefied gas is gasified, and can suppress the complexity and high cost of the structure of the first turbine 2. As a result, the high cost of the power recovery system 1 can be suppressed, and the high cost of the floating structures 100 equipped with the power recovery system 1 can be suppressed.

[0112] Furthermore, as in the above-described embodiments, by suppressing the increase in size of the power recovery system 1 , the space occupied by the power recovery system 1 in the floating structure 100 can be reduced, so that the free space of the floating structure 100 can be effectively utilized.

[0113] The present invention is not limited to the above-described embodiment, and includes modified embodiments of the above-described embodiment and embodiments in which these embodiments are appropriately combined.

[0114] The contents described in the above-mentioned several embodiments can be understood as follows, for example.

[0115] 1) A power recovery system 1 according to at least one embodiment of the present invention recovers power from liquefied gas supplied from a liquefied gas storage device 31 storing liquefied gas, and the power recovery system comprises:

[0116] a first turbine 2 driven by gas from the liquefied gas supplied from the liquefied gas storage device 31;

[0117] a first leakage gas introduction pipe 14 for guiding the gas leaking from the shaft seal portion 24 of the first turbine 2; and

[0118] A gas combustion device 51 is provided for burning the gas introduced through the first leaked gas introduction pipe 14 .

[0119] According to the structure of 1) above, the power recovery system can guide the gas (first leakage gas) leaking from the shaft seal portion of the first turbine to the gas combustion device through the first leakage gas inlet pipe, and the gas combustion device performs combustion treatment. The power recovery system can suppress the first leakage gas from flowing into the atmosphere by performing combustion treatment on the first leakage gas by the gas combustion device. Therefore, even if the power recovery system does not set the sealing performance of the shaft seal portion of the first turbine to high performance as in the past, it is still possible to suppress the gas from leaking from the first turbine to the atmosphere. In addition, the power recovery system can use the first leakage gas as fuel for the gas combustion device 51 by performing combustion treatment on the first leakage gas by the gas combustion device.

[0120] In addition, according to the structure of 1) above, the power recovery system does not need to set the sealing performance of the shaft seal of the first turbine to high performance as in the past, so the structure of the shaft seal of the first turbine can be made simpler than in the past. As a result, the complexity and high cost of the structure of the first turbine can be suppressed, and the high cost of the power recovery system can be suppressed.

[0121] 2) In some embodiments, according to the power recovery system 1 described in 1) above, wherein:

[0122] The liquefied gas storage device 31 is further provided with a boil-off gas introduction pipe 16 for guiding the boil-off gas vaporized in the liquefied gas storage device 31 to the gas combustion device 51 .

[0123] According to the structure of 2) above, the power recovery system can guide the boil-off gas gasified by the liquefied gas storage device to the gas combustion device through the boil-off gas introduction pipe, and the gas combustion device performs combustion treatment. Therefore, the power recovery system can use the boil-off gas as fuel for the gas combustion device by burning the boil-off gas by the gas combustion device.

[0124] In addition, according to the configuration of 2), the power recovery system can burn the first leaked gas and the boil-off gas using a common gas combustion device. The power recovery system can suppress the increase in size and cost of the power recovery system by using a common gas combustion device.

[0125] 3) In some embodiments, according to the power recovery system 1 described in 2) above,

[0126] One side 161 of the boil-off gas introduction pipe 16 is connected to the liquefied gas storage device 31 , and the other side 162 thereof merges with the first leaked gas introduction pipe 14 .

[0127] According to the structure of 3) above, the power recovery system uses the downstream side of the confluence of the first leakage gas introduction pipe and the boil-off gas introduction pipe as a common portion, and can guide the first leakage gas and the boil-off gas to the gas combustion device through the common portion. In this case, the gas combustion device does not need to be provided with gas introduction ports for introducing gas to the first leakage gas and the boil-off gas, respectively, so that the complexity and cost of the structure of the gas combustion device can be suppressed.

[0128] 4) In some embodiments, the power recovery system 1 according to any one of 1) to 3) above further comprises:

[0129] a first compressor 56 , the first compressor 56 being configured to compress air;

[0130] a first compressed air introduction pipe 57, the first compressed air introduction pipe 57 is used to introduce the compressed air compressed by the first compressor 56 into the gas combustion device 51; and

[0131] The first compressed air supply pipe 17 branches off from the first compressed air introduction pipe 57 and guides a part of the compressed air to the shaft seal portion 24 of the first turbine 2 .

[0132] According to the structure of 4) above, the power recovery system guides a part of the compressed air compressed by the first compressor to the shaft seal of the first turbine through the first compressed air supply pipe and uses it as an air seal, thereby suppressing the gas (first leakage gas) from leaking from the shaft seal of the first turbine. In addition, the power recovery system uses the compressed air compressed by the first compressor as an air seal, and can guide the first leakage gas to the gas combustion device in a state of being pre-mixed with compressed air, thereby improving the combustion efficiency of the gas combustion device.

[0133] 5) In some embodiments, according to the power recovery system 1 described in 4) above,

[0134] The shaft seal portion 24 of the first turbine 2 includes:

[0135] a downstream side sealing portion 24B that seals between the rotating shaft 21 of the first turbine 2 and the housing 23 of the first turbine 2; and

[0136] The upstream side sealing portion 24A seals between the rotating shaft 21 and the housing 23 on the upstream side of the downstream side sealing portion 24B.

[0137] The first compressed air supply pipe communicates with a space 231 formed between the downstream-side seal portion 24B and the upstream-side seal portion 24A.

[0138] According to the structure of 5) above, the power recovery system can guide a part of the compressed air compressed by the first compressor to the space formed between the downstream side sealing part and the upstream side sealing part of the first turbine through the first compressed air supply pipe. As a result, compared with the case where the compressed air is not introduced into the above space, the pressure difference between the upstream side of the upstream side sealing part and the downstream side of the upstream side sealing part can be reduced, so that the gas can be suppressed from leaking to the downstream side of the upstream side sealing part. As a result, the gas (first leakage gas) can be suppressed from leaking from the shaft seal of the first turbine.

[0139] 6) In some embodiments, according to the power recovery system 1 described in 5) above, wherein:

[0140] The upstream side seal portion 24A and the downstream side seal portion 24B are formed of a labyrinth seal 24C.

[0141] As described above, the power recovery system performs combustion treatment on the first leaked gas by a gas combustion device, thereby being able to suppress gas leakage from the first turbine to the atmosphere even if the sealing performance of the shaft seal portion of the first turbine is not set to high performance as in the past. According to the structure of 6) above, by using a labyrinth seal for sealing the shaft seal portion (upstream side seal portion and downstream side seal portion) of the first turbine, gas leakage from the first turbine to the atmosphere can be fully suppressed. In addition, by using a labyrinth seal with a simple structure for sealing in the shaft seal portion 4 of the first turbine, the complexity and high cost of the structure of the first turbine can be suppressed, and thus the high cost of the power recovery system can be suppressed.

[0142] 7) In some embodiments, the power recovery system 1 according to any one of 1) to 6) above further comprises:

[0143] an air extraction pipe 61 that extracts the gas from the first turbine 2 and returns the gas to the downstream side of the gas extraction position P1 in the first turbine 2; and

[0144] The reheater 62 is configured to heat the gas flowing through the exhaust pipe 61 .

[0145] According to the structure of 7) above, a part of the gas expanded in the first turbine is returned to the downstream side of the extraction position in the first turbine through the extraction pipe after being extracted by the extraction pipe and heated by the reheater. That is, the power recovery system adopts a reheat cycle. In this case, the power recovery system can suppress the increase of the steam wetness at the end of expansion (near the last stage) in the first turbine by heating the gas with the reheater, thereby suppressing the erosion of the turbine blades near the last stage and achieving an improvement in the thermal efficiency of the first turbine.

[0146] 8) In some embodiments, according to the power recovery system 1 described in 7) above,

[0147] The reheater 62 includes a heat exchanger 62A configured to perform heat exchange between the gas flowing in the gas extraction pipe 61 and a heat medium (first heat medium) that performs heat exchange with the liquefied gas supplied from the liquefied gas storage device 31 .

[0148] According to the structure of 8), the heat exchanger is used to heat the gas (exhaust gas) extracted from the first turbine and flowing in the exhaust pipe and the first heat medium. In this case, the structure of the heat exchanger (reheater) can be simplified, and the first heat medium can be used as a heat source for the exhaust gas in the heat exchanger. By using the first heat medium as a heat source for the exhaust gas in the heat exchanger, the condensation of the first heat medium in the condensation process is promoted, thereby achieving an improvement in the thermal efficiency of the second turbine (turbine for the first heat medium).

[0149] 9) In some embodiments, the power recovery system 1 according to any one of 1) to 8) above further comprises:

[0150] a heat medium circulation circuit 4 configured to circulate a heat medium for heat exchange with the liquefied gas supplied from the liquefied gas storage device 31 or the gas discharged from the first turbine 2, and including a second turbine 7 using the heat medium as a working fluid; and

[0151] The second leaked gas introduction pipe 18 is used to guide the working fluid leaking from the shaft seal portion 74 of the second turbine 7 to the gas combustion device 51 .

[0152] According to the structure of 9) above, the power recovery system can guide the gas (second leakage gas) leaking from the shaft seal portion of the second turbine of the heat medium circulation line through the second leakage gas inlet pipe to the gas combustion device, and the gas combustion device performs combustion treatment. The power recovery system can suppress the second leakage gas from flowing into the atmosphere by performing combustion treatment on the second leakage gas by the gas combustion device. Therefore, even if the power recovery system does not set the sealing performance of the shaft seal portion of the second turbine to high performance as in the past, it can suppress the gas from leaking from the second turbine to the atmosphere. In addition, the power recovery system can use the second leakage gas as fuel for the gas combustion device by performing combustion treatment on the second leakage gas by the gas combustion device.

[0153] In addition, according to the structure of 9), the power recovery system does not need to set the sealing performance of the shaft seal of the second turbine to high performance, so the structure of the shaft seal 4 of the second turbine can be made simpler than before. As a result, the complexity and high cost of the structure of the second turbine can be suppressed, and the high cost of the power recovery system can be suppressed.

[0154] 10) In some embodiments, the power recovery system 1 according to 9) above comprises:

[0155] A second compressor 81, the second compressor 81 is configured to compress air;

[0156] A second compressed air introduction pipe 82, the second compressed air introduction pipe 82 is used to introduce the compressed air compressed by the second compressor 81 into the gas combustion device 51; and

[0157] The second compressed air supply pipe 83 branches off from the second compressed air introduction pipe 82 and guides a part of the compressed air compressed by the second compressor 81 to the shaft seal portion 74 of the second turbine 7 .

[0158] According to the structure of 10) above, the power recovery system guides a part of the compressed air compressed by the second compressor to the shaft seal seal portion of the second turbine through the second compressed air supply pipe and uses it as an air seal, thereby suppressing the gas (second leakage gas) from leaking from the shaft seal seal portion of the second turbine. In addition, the power recovery system uses the compressed air compressed by the second compressor as an air seal, and can guide the second leakage gas to the gas combustion device in a state of being pre-mixed with compressed air, thereby improving the combustion efficiency of the gas combustion device.

[0159] 11) A floating structure 100 according to at least one embodiment of the present invention, wherein:

[0160] The power recovery system 1 described in any one of 1) to 10) above is mounted.

[0161] According to the structure of 11), the power recovery system can suppress gas leakage of the turbine driven by the gas after the liquefied gas is vaporized, and can suppress the complexity and high cost of the structure of the turbine. Thus, the high cost of the power recovery system can be suppressed, and further the high cost of the floating structure on the water equipped with the power recovery system can be suppressed.

[0162] Explanation of symbols

[0163] 1 Power recovery system

[0164] 2 First Turbine

[0165] 3 Liquefied gas supply system

[0166] 4 Heat medium circulation circuit

[0167] 4A First heat medium circulation line

[0168] 4B Second heat medium circulation line

[0169] 5. Gas combustion system

[0170] 7 Second Turbine

[0171] 7A Turbine (for the first heat medium)

[0172] 7B Turbine (for the second heat medium)

[0173] 10 Power equipment

[0174] 11. First heat exchanger

[0175] 12. Second heat exchanger

[0176] 13, 44, 48 Generator

[0177] 14 First leaked gas inlet pipe

[0178] 15 Blower

[0179] 16 Evaporation gas inlet pipe

[0180] 17 First compressed air supply pipe

[0181] 18 Second leaked gas inlet pipe

[0182] 18A, 18B Leakage gas inlet pipe

[0183] 21, 71A, 71B Rotation axis

[0184] 22, 72A, 72B turbine blades

[0185] 23, 73A, 73B Housing

[0186] 24, 74, 74A, 74B Shaft seal

[0187] 24A Upstream side seal

[0188] 24B Downstream side seal

[0189] 24C Labyrinth seal

[0190] 25, 52 Gas inlet

[0191] 26 Gas outlet

[0192] 31 Liquefied gas storage device

[0193] 32 Liquefied gas supply line

[0194] 33 Pumps for liquefied gas

[0195] 34 Supply Destination

[0196] 41 First heat medium circulation line

[0197] 42, 46 Circulation pump

[0198] 43 Third heat exchanger

[0199] 45 Second heat medium circulation line

[0200] 47 Fourth heat exchanger

[0201] 51 Gas combustion device

[0202] 53 Air inlet

[0203] 54 Combustion Department

[0204] 55 Exhaust outlet

[0205] 56 First compressor

[0206] 56A Compressor

[0207] 56B Electric compressor

[0208] 57 First compressed air inlet pipe

[0209] 58 Exhaust gas turbine

[0210] 59 Exhaust gas inlet pipe

[0211] 61 exhaust pipe

[0212] 62 Reheater

[0213] 62A Heat Exchanger

[0214] 75A First heat medium inlet

[0215] 75B Second heat medium inlet

[0216] 76A First heat medium outlet

[0217] 76B Second heat medium outlet

[0218] 81 Second compressor

[0219] 82 Second compressed air inlet pipe

[0220] 83 Second compressed air supply pipe

[0221] 83A, 83B Compressed air supply pipe

[0222] 100 Floating Structure

[0223] 100A Ship

[0224] 100B floating body

[0225] 231 Space

[0226] 232 First annular portion

[0227] 233 Second annular part

[0228] 234 Axial extension

[0229] 235 Through hole

[0230] P1 Pumping position

Claims

1. A power recovery system for recovering power from liquefied gas supplied from a liquefied gas storage device for storing liquefied gas, It is characterized in that have: a first turbine driven by gas obtained by vaporizing the liquefied gas supplied from the liquefied gas storage device; a first leakage gas introduction pipe for guiding the gas leaking from the shaft seal portion of the first turbine; a gas combustion device for burning the gas guided by the first leaked gas introduction pipe; a first compressor configured to compress air; a first compressed air introduction pipe, the first compressed air introduction pipe being used to introduce the compressed air compressed by the first compressor into the gas combustion device; as well as A first compressed air supply pipe is branched from the first compressed air introduction pipe and is used to guide a part of the compressed air to the shaft seal portion of the first turbine.

2. The power recovery system according to claim 1, It is characterized in that The device further includes a boil-off gas introduction pipe for guiding boil-off gas vaporized by the liquefied gas storage device to the gas combustion device.

3. The power recovery system according to claim 2, It is characterized in that One side of the boil-off gas introduction pipe is connected to the liquefied gas storage device, and the other side thereof merges with the first leaked gas introduction pipe.

4. The power recovery system according to any one of claims 1 to 3, It is characterized in that The shaft seal portion of the first turbine includes: a downstream side sealing portion that seals between a rotating shaft of the first turbine and a housing of the first turbine; and an upstream side sealing portion that seals between the rotating shaft and the housing on the upstream side of the downstream side sealing portion, The first compressed air supply pipe communicates with a space formed between the downstream-side sealing portion and the upstream-side sealing portion.

5. The power recovery system according to claim 4, It is characterized in that The upstream side sealing portion and the downstream side sealing portion are formed of labyrinth seals.

6. The power recovery system according to any one of claims 1 to 3, It is characterized in that Also available: an air extraction pipe that extracts the gas from the first turbine and returns the gas to a downstream side of a gas extraction position of the gas in the first turbine; and A reheater is configured to heat the gas flowing through the exhaust pipe.

7. The power recovery system according to claim 6, It is characterized in that The reheater includes a heat exchanger configured to perform heat exchange between the gas flowing in the gas extraction pipe and a heat medium that performs heat exchange with the liquefied gas supplied from the liquefied gas storage device.

8. The power recovery system according to any one of claims 1 to 3, It is characterized in that Also available: a heat medium circulation circuit configured to circulate a heat medium for exchanging heat with the liquefied gas supplied from the liquefied gas storage device or the gas discharged from the first turbine, and including a second turbine using the heat medium as a working fluid; as well as A second leaked gas introduction pipe is used to guide the working fluid leaking from the shaft seal portion of the second turbine to the gas combustion device.

9. The power recovery system according to claim 8, It is characterized in that have: a second compressor configured to compress air; a second compressed air introduction pipe, the second compressed air introduction pipe being used to introduce the compressed air compressed by the second compressor into the gas combustion device; as well as A second compressed air supply pipe is branched from the second compressed air introduction pipe and is used to guide a part of the compressed air compressed by the second compressor to the shaft seal portion of the second turbine.

10. A floating structure on water, It is characterized in that The power recovery system according to any one of claims 1 to 9 is mounted.

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