JP2018119511A - Natural gas burning combined cycle power generation system and natural gas burning combined cycle power generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a natural gas burning combined cycle power generation system capable of restricting the ice accretion in a carburetor.SOLUTION: A natural gas burning combined cycle power generation system 1 comprises: a carburetor 10; a chiller 20; a circulation flow passage 30; a pump 40; and a gas turbine-combined power generator 50. The carburetor 10 includes: an intermediate medium evaporation part E1 for evaporating at least a part of an intermediate medium M by heat exchanging between the intermediate medium M having a freezing point lower than that of water and the water outflowing from the chiller 20; and a natural gas vaporization part E2 for evaporating at least a part of liquefaction natural gas by heat exchanging between the intermediate medium M and the liquefaction natural gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a natural gas-fired combined cycle power generation system.

  Conventionally, there has been known a natural gas-fired combined cycle power generation system that uses cold heat recovered from liquefied natural gas in a vaporizer for vaporizing liquefied natural gas (LNG) to cool air supplied to a gas turbine combined power generation device. Yes.

  For example, Patent Document 1 discloses an LNG-fired combined cycle power generation including an LNG vaporizer, a gas turbine intake air cooler, a gas turbine intake cooling water circulation system, a gas turbine intake cooling water circulation pump, and a gas turbine power generation device. Equipment is disclosed. The LNG vaporizer includes a heat transfer tube for flowing LNG. In this LNG vaporizer, LNG is vaporized by exchanging heat between LNG flowing in the heat transfer tube and water contacting the surface of the heat transfer tube. The gas turbine intake air cooler cools air by causing heat exchange between water (cooling water) flowing out from the LNG vaporizer and air. The gas turbine intake cooling water circulation system path connects the LNG vaporizer and the gas turbine intake cooler. Water flows through the LNG vaporizer and the gas turbine intake air cooler in this order by circulating through the gas turbine intake cooling water circulation system. The gas turbine intake cooling water circulation pump is provided in a portion of the gas turbine intake cooling water circulation system downstream of the gas turbine intake cooler. A gas turbine power generator includes a gas turbine compressor that compresses air that flows out of a cooler, a gas turbine that is driven by a mixed gas of air discharged from the gas turbine compressor and combustion gas of natural gas (NG), and And a generator connected to the gas turbine. In this facility, the air supplied to the gas turbine compressor of the gas turbine power generation apparatus is cooled by the cold heat recovered from the LNG by the LNG vaporizer.

Japanese Patent Laid-Open No. 06-213001

  In the vaporizer of the LNG-fired combined cycle power generation facility described in Patent Document 1, icing may occur on the surface of the heat transfer tube through which LNG flows.

  An object of the present invention is to provide a natural gas-fired combined cycle power generation system and a natural gas-fired combined cycle power generation method capable of suppressing the occurrence of icing in a vaporizer.

  As means for solving the above-mentioned problems, the present invention is a natural gas-fired combined cycle power generation system, wherein a vaporizer that vaporizes at least a part of the liquefied natural gas by heating the liquefied natural gas with water, and the vaporization A cooler that cools the air by exchanging heat between the water flowing out of the vessel and the air, and a circulating flow that connects the vaporizer and the cooler so that water flows through the vaporizer and the cooler in this order. A gas turbine combined with a gas turbine generator connected to the gas turbine generator connected to the gas turbine driven by the path, the pump provided in the circulation channel, the gas including the air flowing out from the cooler, and the gas turbine; The vaporizer exchanges heat between the intermediate medium having a freezing point lower than the freezing point of water and the water flowing out of the cooler. An intermediate medium evaporating unit that evaporates at least a part of the intermediate medium, and a liquefied natural gas vaporizing unit that evaporates at least a part of the liquefied natural gas by exchanging heat between the intermediate medium and the liquefied natural gas. And providing a natural gas-fired combined cycle power generation system.

  In this natural gas-fired combined cycle power generation system, heat exchange between water and liquefied natural gas is performed via an intermediate medium (such as propane) having a freezing point lower than the freezing point of water. Is suppressed.

  Further, in the natural gas-fired combined cycle power generation system, the natural gas flowing out from the liquefied natural gas vaporization section and the cooling provided in a portion of the circulation channel between the cooler and the vaporizer It is preferable to further include a heating unit that heats the natural gas by exchanging heat with water flowing out of the vessel.

  In this way, the structure is simplified as compared with the case where the natural gas flowing out from the liquefied natural gas vaporizing section is heated by a heating medium different from the water flowing out from the cooler.

  In this case, it is preferable to further include a direct expansion turbine driven by the natural gas flowing out from the heating unit, and an expansion turbine generator connected to the direct expansion turbine.

  If it does in this way, since the energy which the natural gas which flowed out from the heating part has is collect | recovered as electric power in an expansion turbine generator, the electric power generation amount as the whole system will increase.

  Furthermore, in this case, a heater bypass channel that is connected to the circulation channel and bypasses the heating unit, water that flows through the heating unit bypass channel, and natural gas that flows out of the direct expansion turbine, It is preferable to further include an additional heating unit that heats the natural gas by exchanging heat.

  If it does in this way, it will raise the temperature of the natural gas which decreased by passing the expansion turbine directly with the water which flowed out of the cooler rather than the heating medium for exclusive use for heating the natural gas which flowed out of the direct expansion turbine directly be able to. Specifically, although the temperature of the natural gas decreases as natural gas passes directly through the expansion turbine, the heating unit bypass is used instead of a part of the heat quantity of water flowing out of the cooler being input to the heating unit. Since it is introduced into the additional heating section through the flow path, the natural gas flowing out from the direct expansion turbine is effectively heated. Even after the natural gas is heated in the additional heating section, water has a sufficient amount of heat, so that the intermediate medium is effectively heated in the intermediate medium evaporation section by the water.

  The natural gas-fired combined cycle power generation system preferably further includes a casing that collectively accommodates the heating unit and the additional heating unit.

  If it does in this way, compared with the case where a warming part and an additional warming part are accommodated in a respectively different casing, the structure of a warming part and an additional warming part will be simplified and it will be reduced in size.

  In this case, it is preferable that the heating unit is configured to be detachable from the casing.

  If it does in this way, cleaning (washing) in a heating part and a casing will become easy.

  Moreover, in the natural gas-fired combined cycle power generation system, the additional heating unit is preferably configured to be detachable from the casing.

  If it does in this way, cleaning (washing) in an additional heating part and a casing will become easy.

  Further, in the natural gas-fired combined cycle power generation system, a cooler bypass flow path that is connected to the circulation flow path and bypasses the cooler, and a cold heat recovery unit provided in the cooler bypass flow path, It is preferable to further provide.

  If it does in this way, the excessive amount of cold heat required for cooling the air in the cooler is effectively recovered by the cold energy recovery unit.

  The present invention also provides cold gas recovered from the liquefied natural gas in a vaporizer for vaporizing liquefied natural gas to a gas turbine combined power generator having a gas turbine and a gas turbine generator connected to the gas turbine. A natural gas-fired combined cycle power generation method used for cooling the generated air, wherein the liquefied natural gas is heated by water to evaporate at least a part of the liquefied natural gas, and water is used in the vaporization step. A cooling step of cooling air supplied to the gas turbine combined power generation device by cold heat recovered from the liquefied natural gas, and in the vaporization step, the air is cooled in the cooling step in the vaporizer. The heat recovered from the air by the water is supplied to an intermediate medium having a freezing point lower than the freezing point of water. Evaporating at least a part of the intermediate medium, and evaporating at least a part of the liquefied natural gas by heating the liquefied natural gas with the intermediate medium. A combined cycle power generation method is provided.

  In the vaporization process of this natural gas-fired combined cycle power generation method, liquefied natural gas is vaporized in the vaporizer via an intermediate medium (such as propane) having a freezing point lower than the freezing point of water. Ice generation is suppressed.

  As described above, according to the present invention, it is possible to provide a natural gas-fired combined cycle power generation system and a natural gas-fired combined cycle power generation method capable of suppressing the occurrence of icing in the vaporizer.

It is a figure which shows the outline of a structure of the natural gas fired combined cycle power generation system of 1st Embodiment of this invention. It is an enlarged view of the circumference | surroundings of the vaporizer | carburetor and warmer of 1st Embodiment. It is a figure which shows the modification of the natural gas fired combined cycle electric power generation system shown in FIG. It is a figure which shows the outline of a structure of the natural gas fired combined cycle power generation system of 2nd Embodiment of this invention. It is an enlarged view of the circumference | surroundings of the vaporizer | carburetor and warmer of 2nd Embodiment.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
A natural gas-fired combined cycle power generation system 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The natural gas-fired combined cycle power generation system 1 is configured to supply cold gas recovered from liquefied natural gas through water in a vaporizer 10 for vaporizing liquefied natural gas (LNG) to the gas turbine combined power generation device 50. The power generation system generates power with the gas turbine combined power generation device 50 while being used for cooling. Specifically, the natural gas-fired combined cycle power generation system 1 includes a vaporizer 10, a cooler 20, a circulation channel 30, a pump 40, and a gas turbine combined power generation device 50. The circulation channel 30 connects the vaporizer 10 and the cooler 20 in this order.

  The vaporizer 10 is an intermediate medium vaporizer (IFV) that vaporizes liquefied natural gas by exchanging water and liquefied natural gas through an intermediate medium (propane or the like) having a freezing point lower than the freezing point of water. is there. That is, in the vaporizer 10, the intermediate medium is heated by water, not brine or the like, and the liquefied natural gas is heated by the intermediate medium. Details of the vaporizer 10 will be described later.

  The cooler 20 cools the air by exchanging heat between the water flowing out of the vaporizer 10 and the air.

  The pump 40 is provided in a portion of the circulation channel 30 on the downstream side of the vaporizer 10. The pump 40 sends water (cooling water) flowing out from the vaporizer 10 to the cooler 20. In the present embodiment, the pump 41 is also provided in a portion of the circulation channel 30 on the downstream side of the cooler 20. The pump 41 sends water (warm water) flowing out from the cooler 20 to the vaporizer 10. Further, a cold storage tank 42 having a function of storing cold heat may be provided in a portion of the circulation channel 30 between the vaporizer 10 and the pump 40. Similarly, a thermal storage tank 43 having a function of storing thermal heat may be provided in a portion of the circulation channel 30 between the cooler 20 and the pump 41. Further, a backup heater 44 that heats water by a heat source (seawater or the like) may be provided in a portion of the circulation channel 30 between the cooler 20 and the thermal storage tank 43.

  The gas turbine combined power generation apparatus 50 includes an air compressor 51, a gas turbine 52, an exhaust heat recovery boiler 53, a steam turbine 54, and a gas turbine generator 55. The air compressor 51 compresses the air that has flowed out of the cooler 20. The gas turbine 52 is driven by a mixed gas of compressed air discharged from the air compressor 51 and combustion gas generated by combustion of natural gas (NG). The exhaust heat recovery boiler 53 evaporates water by exchanging heat between the exhaust gas discharged from the gas turbine 52 and water. The steam turbine 54 is driven by steam that has flowed out of the exhaust heat recovery boiler 53. The gas turbine generator 55 is connected to the gas turbine 52 and the steam turbine 54, and generates electric power by their rotation.

  The natural gas-fired combined cycle power generation system 1 may further include a heater 60 provided in a portion of the circulation channel 30 between the cooler 20 and the vaporizer 10.

  Here, the vaporizer 10 and the heater 60 will be described with reference to FIG.

  The vaporizer 10 includes an intermediate medium evaporation unit E1, a liquefied natural gas vaporization unit E2, and a shell 11 that can accommodate the intermediate medium evaporation unit E1, the liquefied natural gas vaporization unit E2, and the intermediate medium M.

  The intermediate medium evaporating unit E1 evaporates at least a part of the intermediate medium M by exchanging heat between the liquid-phase intermediate medium M and the water (hot water) flowing out of the cooler 20. In this embodiment, the intermediate medium evaporation part E1 is comprised with the heat exchanger tube. The intermediate medium evaporating section E1 is disposed in a lower portion of the shell 11 (a position in the shell 11 where the liquid medium intermediate medium M is immersed). That is, the intermediate medium M in contact with the intermediate medium evaporator E1 is heated by the water flowing in the intermediate medium evaporator E1.

  The liquefied natural gas vaporization section E2 vaporizes at least a part of the liquefied natural gas by exchanging heat between the liquefied natural gas and the gas phase intermediate medium M. In this embodiment, the liquefied natural gas vaporization part E2 is comprised with the heat exchanger tube formed in the U-shape. The liquefied natural gas vaporization section E2 is disposed in an upper portion of the shell 11 (a region above the surface of the liquid phase intermediate medium M in the shell 11). That is, the liquefied natural gas flowing in the liquefied natural gas vaporization section E2 is heated by the gas phase intermediate medium M in contact with the surface of the liquefied natural gas vaporization section E2.

  An inlet chamber 12 and an outlet chamber 13 that are partitioned by a partition plate 14 are connected to the shell 11. The inlet chamber 12 is connected to one end of the liquefied natural gas vaporizer E2 so that the inlet chamber 12 and the liquefied natural gas vaporizer E2 communicate with each other. The outlet chamber 13 is connected to the other end of the liquefied natural gas vaporization unit E2 so that the inside of the outlet chamber 13 and the liquefied natural gas vaporization unit E2 communicate with each other. That is, at least a part of the liquefied natural gas flowing into the liquefied natural gas vaporization section E2 from the inlet chamber 12 is heated by the gas phase intermediate medium M while passing through the liquefied natural gas vaporization section E2. And flows into the outlet chamber 13.

  In addition, a water inlet chamber 15 and a water outlet chamber 16 are connected to the shell 11. The water inlet chamber 15 is connected to one side of the shell 11 so that the water inlet chamber 15 and the intermediate medium evaporation part E1 communicate with each other. The water outlet chamber 16 is connected to the other side of the shell 11 so that the inside of the water outlet chamber 16 and the inside of the intermediate medium evaporation part E1 communicate with each other. That is, the water that has flowed into the intermediate medium evaporator E1 from the water inlet chamber 15 recovers cold heat from the liquid intermediate medium M in the process of passing through the intermediate medium evaporator E1, and circulates through the water outlet chamber 16. It flows out to the flow path 30.

  The warmer 60 is provided in a portion of the circulation channel 30 on the upstream side of the vaporizer 10. The warmer 60 heats the natural gas flowing out of the vaporizer 10. The warmer 60 includes a warming part E3 and a casing 61 that houses the warming part E3.

  The heating unit E3 heats the natural gas by exchanging heat between the natural gas flowing out from the liquefied natural gas vaporizing unit E2 and the water flowing out from the cooler 20. In this embodiment, the heating part E3 is comprised by the heat exchanger tube formed in U shape.

  An inlet chamber 62 and an outlet chamber 63 that are partitioned by a partition plate 64 are connected to the casing 61 via a flange 65. The configurations of the inlet chamber 62 and the outlet chamber 63 are the same as the configurations of the inlet chamber 12 and the outlet chamber 13 connected to the shell 11. The natural gas flowing out from the outlet chamber 13 of the vaporizer 10 flows into the inlet chamber 62, is heated by the water in the casing 61 in the process of passing through the heating unit E <b> 3, and flows into the outlet chamber 63. The flange 65 is detachably connected to the casing 61. That is, the heating unit E3, the inlet chamber 62, the outlet chamber 63, and the partition plate 64 can be detached from the casing 61.

  As shown in FIG. 1, the natural gas-fired combined cycle power generation system 1 has a calorific value adjustment channel 31. The calorie adjustment channel 31 is connected to the circulation channel 30 and bypasses the heater 60. For this reason, the water that has flowed out of the cooler 20 and then passed through the warmer 60 and the water that has passed through the calorific value adjustment flow channel 31 flow into the intermediate medium evaporation section E1.

  As described above, in the natural gas-fired combined cycle power generation system 1 of the present embodiment, heat exchange between water and liquefied natural gas is performed via an intermediate medium (such as propane) having a freezing point lower than the freezing point of water. Therefore, compared with the case where water and liquefied natural gas directly exchange heat, the occurrence of icing in the intermediate medium evaporation section E1 is suppressed. Moreover, it is not necessary to use expensive brine water (ethylene glycol water or the like) as a cooling medium in order to prevent icing trouble.

  In addition, a heater 60 that heats natural gas with water flowing out of the cooler 20 is provided on the upstream side of the vaporizer 10. For this reason, natural gas is heated by a simple structure compared with the case where the natural gas which flowed out from the liquefied natural gas vaporization part E2 is heated with the heating medium different from the water which flowed out from the cooler 20.

  Further, in the heater 60, the heating unit E <b> 3, the inlet chamber 62, the outlet chamber 63, and the partition plate 64 can be removed from the casing 61. For this reason, cleaning (washing) in the heating part E3 and the casing 61 becomes easy.

  As shown in FIG. 3, the natural gas-fired combined cycle power generation system 1 may further include a cooler bypass passage 32 and a cold heat recovery unit 45. The cooler bypass channel 32 is connected to the circulation channel 30 and bypasses the cooler 20. The cold heat recovery unit 45 recovers the cold heat of the water that has flowed out of the vaporizer 10. Examples of the cold heat recovery unit 45 include a cooling device that cools a room or a cable pit. In this aspect, the cold energy surplus necessary for cooling the air in the cooler 20 is effectively recovered by the cold energy recovery unit 45.

(Second Embodiment)
Next, a natural gas fired combined cycle power generation system 1 according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. In the second embodiment, only parts different from the first embodiment will be described, and the description of the same structure, operation, and effect as in the first embodiment will be omitted.

  The natural gas fired combined cycle power generation system 1 of the present embodiment further includes a direct expansion turbine 80, an expansion turbine generator 90, a heating unit bypass flow path 33, and an additional heating unit E4.

  The direct expansion turbine 80 is driven by natural gas flowing out from the heating unit E3. The expansion turbine generator 90 is directly connected to the expansion turbine 80.

  The heating part bypass flow path 33 is connected to the circulation flow path 30 and bypasses the heating part E3.

  The additional heating unit E4 is provided in the heating unit bypass flow path 33. The additional heating unit E4 heats the natural gas by exchanging heat between the water flowing through the heating unit bypass passage 33 and the natural gas directly flowing out from the expansion turbine 80. The additional heating part E4 is configured by a heat transfer tube formed in a U shape. In the present embodiment, the additional heating unit E4 is accommodated in the casing 61. In other words, the casing 61 of the present embodiment has a shape that can accommodate the heating part E3 and the additional heating part E4 together. An inlet chamber 72 and an outlet chamber 73 that are partitioned by a partition plate 74 are further connected to the casing 61 via a flange 75. The inlet chamber 72 and the outlet chamber 73 communicate with the inside of the additional heating unit E4. The natural gas that has flowed directly from the expansion turbine 80 flows into the inlet chamber 72, and then is heated by the water that flows into the casing 61 through the heating section bypass flow path 33 in the process of passing through the additional heating section E4. It flows into the outlet chamber 73. This additional heating part E4 can also be removed from the casing 61 together with the inlet chamber 72, the outlet chamber 73 and the partition plate 74. For this reason, cleaning (washing) of the additional heating part E4 is also facilitated.

  Moreover, in this embodiment, since the energy which the natural gas which flowed out from the heating part E3 has is collect | recovered as electric power in the expansion turbine generator 90, the electric power generation amount as the whole system increases.

  Further, the temperature of the natural gas lowered by passing directly through the expansion turbine 80 is not increased by a dedicated heating medium for heating the natural gas flowing out from the direct expansion turbine 80 but by water discharged from the cooler 20. Can do. Specifically, although the temperature of the natural gas decreases as the natural gas passes directly through the expansion turbine 80, a part of the heat quantity of the water flowing out of the cooler 20 is added instead of being input to the heating unit E3. Since the additional warming section E4 is introduced through the warm section bypass flow path 33, the natural gas flowing out of the direct expansion turbine 80 is effectively heated. Even after the natural gas is heated in the additional heating section E4, the water has a sufficient amount of heat, so that the intermediate medium M is effectively heated in the intermediate medium evaporation section E1 by the water.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, the heating part E3 and the additional heating part E4 may be accommodated in different casings. Even in this case, it is preferable that the water flowing out from the additional heating unit E4 is supplied to the intermediate medium evaporation unit E1.

DESCRIPTION OF SYMBOLS 1 Natural gas fired combined cycle power generation system 10 Vaporizer 20 Cooler 30 Circulation flow path 32 Cooler bypass flow path 33 Heater bypass flow path 40 Pump 45 Cold-heat recovery part 50 Gas turbine combined power generation apparatus 52 Gas turbine 54 Steam turbine 55 Gas turbine generator 60 Heater 70 Heater 80 Expansion turbine E1 Intermediate medium evaporation section E2 Liquefied natural gas vaporization section E3 Heating section E4 Additional heating section M Intermediate medium

Claims (10)

A natural gas-fired combined cycle power generation system,
A vaporizer that vaporizes at least a portion of the liquefied natural gas by heating the liquefied natural gas with water;
A cooler that cools the air by exchanging heat between the water flowing out of the vaporizer and the air;
A circulation flow path connecting the vaporizer and the cooler so that water flows in this order through the vaporizer and the cooler;
A pump provided in the circulation channel;
A gas turbine driven by a gas containing air flowing out of the cooler, and a gas turbine combined power generation device having a gas turbine generator connected to the gas turbine,
The vaporizer is
An intermediate medium evaporation section that evaporates at least a part of the intermediate medium by heat-exchanging the intermediate medium having a freezing point lower than the freezing point of water and the water flowing out of the cooler;
A natural gas-fired combined cycle power generation system comprising: a liquefied natural gas vaporization unit that vaporizes at least a part of the liquefied natural gas by exchanging heat between the intermediate medium and the liquefied natural gas. In the natural gas fired combined cycle power generation system according to claim 1,
By providing heat exchange between the natural gas flowing out from the liquefied natural gas vaporization section and the water flowing out from the cooler, provided in a portion of the circulation channel between the cooler and the vaporizer. A natural gas-fired combined cycle power generation system further comprising a heating unit for heating the natural gas. In the natural gas fired combined cycle power generation system according to claim 2,
A direct expansion turbine driven by natural gas flowing out of the heating section;
A natural gas-fired combined cycle power generation system further comprising an expansion turbine generator connected to the direct expansion turbine. In the natural gas-fired combined cycle power generation system according to claim 3,
A heating section bypass flow path that is connected to the circulation path and bypasses the heating section;
A natural gas-fired combined cycle power generation, further comprising: an additional heating unit that heats the natural gas by exchanging heat between the water flowing through the heating unit bypass flow path and the natural gas flowing out of the direct expansion turbine. system. In the natural gas fired combined cycle power generation system according to claim 4,
A natural gas-fired combined cycle power generation system, further comprising a casing that collectively accommodates the heating unit and the additional heating unit. In the natural gas fired combined cycle power generation system according to claim 5,
The heating unit is a natural gas-fired combined cycle power generation system configured to be detachable from the casing. In the natural gas-fired combined cycle power generation system according to claim 5 or 6,
The additional heating unit is a natural gas-fired combined cycle power generation system configured to be detachable from the casing. In the natural gas-fired combined cycle power generation system according to any one of claims 1 to 7,
A cooler bypass channel connected to the circulation channel and bypassing the cooler;
A natural gas-fired combined cycle power generation system, further comprising: a cold heat recovery unit provided in the cooler bypass flow path.   A vaporizer used in the natural gas-fired combined cycle power generation system according to any one of claims 1 to 8. The cooling heat recovered from the liquefied natural gas in the vaporizer for vaporizing the liquefied natural gas is used for cooling the air supplied to the gas turbine combined power generation device having the gas turbine and the gas turbine generator connected to the gas turbine. A natural gas-fired combined cycle power generation method to be used,
A vaporization step of vaporizing at least a part of the liquefied natural gas by heating the liquefied natural gas with water;
A cooling step of cooling the air supplied to the gas turbine combined power generation device by the cold heat recovered from the liquefied natural gas in the vaporization step,
In the vaporization step, in the vaporizer, at least the intermediate medium is supplied by supplying heat recovered from the air by cooling the air in the cooling step to an intermediate medium having a freezing point lower than the freezing point of water. A natural gas-fired combined cycle power generation method, comprising evaporating a part and evaporating at least a part of the liquefied natural gas by heating the liquefied natural gas with the intermediate medium.

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