JP2015206476A - oxygen concentration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen concentration system capable of changing a production volume of oxygen-enriched air and inexpensively producing the oxygen-enriched air regardless of the production volume thereof.SOLUTION: An oxygen concentration system 10 comprises: a compressor 15 to compress air which exchanges heat with liquidated natural gas in a heat exchanger 14; an expander 18 to perform adiabatic expansion of the air which exchanges the heat with the liquidated natural gas in a heat exchanger 16 after being compressed by the compressor 15; and a gas-liquid separator 19 to perform gas-liquid separation of the air subjected to the adiabatic expansion. A compression ratio of the compressor 15 and an expansion ratio of the expander 18 are respectively set so that a temperature of the air after the adiabatic expansion is higher than a boiling point of nitrogen and lower than the same of oxygen. The compressor 15 and the expander 18 are a screw type where a compressor's female rotor 156 and an expander's female rotor 182 are connected to each other and a compressor's male rotor 157 and an expander's male rotor 183 are connected to each other for the integral rotations. A motor 17 rotates a rotation body including the compressor's male rotor 157 and the expander's male rotor 183.

Description

  The present invention relates to an oxygen enrichment system.

In recent years, in order to reduce CO ₂ emissions due to global environmental problems, facilities (equipment) that use combustion heat sources such as blast furnaces and power generation fuel NG (natural gas) that emits relatively little CO ₂ when burned. It is used as As a method of improving thermal efficiency in order to reduce fuel costs when using this NG as fuel, oxygen (pure oxygen) or oxygen-enriched air having a higher oxygen concentration than the atmosphere is blown in place of the atmosphere (air). Thus, there is a method of burning NG at a higher temperature and suppressing the amount of heat taken by nitrogen in the atmosphere. As such an apparatus for producing pure oxygen used for combustion of NG at a higher temperature in a relatively large amount and with high productivity, for example, a cryogenic separation type air separation apparatus described in Patent Document 1 below is used. Generally known.

  This cryogenic separation type air separation device cools air to a very low temperature and liquefies it, and then fractionates oxygen from the liquefied air in the rectification column using the difference in boiling point between oxygen and nitrogen. At this time, in the air separation device, there are proposals and attempts to reduce the production cost of oxygen by using the cold heat of LNG (liquefied NG) as a low temperature source when liquefying air, but it is not so common. Absent. Specifically, in a facility that uses a combustion heat source that uses NG as fuel, it is usually stored in a tank or the like in a state where NG is liquefied and its volume is reduced to, for example, about 1/600, ie, LNG (liquefied natural gas) The temperature of LNG stored in this tank is kept at an extremely low temperature of −162 ° C. or lower, which is the boiling point thereof. For this reason, in principle, in the air separation device, it is possible to liquefy the air using the cold heat of the LNG to suppress consumption of electric power or the like when cooling oxygen.

  According to such a cryogenic separation type air separation device, the purity is 99.6 vol. % Or more of high-purity oxygen (pure oxygen) can be obtained.

JP-A-6-11254

  The air supplied for NG combustion at a higher temperature is not necessarily high-purity oxygen such as pure oxygen, but oxygen-enriched air having a higher oxygen concentration than normal air having an oxygen concentration of 21%, For example, oxygen-enriched air having an oxygen concentration of about 30% to 50% may be used. Combustion performed by supplying such oxygen-enriched air is called oxygen-enriched combustion. The air separation apparatus is an apparatus designed to produce high-purity oxygen and high-purity nitrogen as industrial raw materials. For this reason, when the purpose is to produce oxygen-enriched air to be supplied to oxygen-enriched combustion, such an air separation device produces oxygen with an unnecessarily pure purity. Energy such as electric power is consumed. For this reason, extra cost will arise.

  Here, it is conceivable to produce oxygen-enriched air by mixing high-purity oxygen produced by an air separation device and normal air, but in the method for producing oxygen by the cryogenic separation method as described above, Since it is not economical unless large-scale oxygen production exceeding 30 t / day is performed, if a small amount of oxygen-enriched air is required, the cost is significantly increased and oxygen-enriched air is produced at a low cost. Can not do it.

  Moreover, in the above air separation device, because of the operation principle of the cryogenic separation method and the characteristics of the molecular thermal fluid, there are a load fluctuation amount restriction and a load fluctuation speed restriction, so the amount of oxygen produced per unit time is low. The operation must be as constant as possible. For this reason, the production amount of oxygen per unit time cannot be changed.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to change the production amount of oxygen-enriched air and to produce oxygen-enriched air at a low cost regardless of the production amount. It is to provide a possible oxygen enrichment system.

  In order to achieve the above object, an oxygen concentrating system according to one aspect of the present invention is an oxygen concentrating system for increasing the oxygen concentration of input air, wherein the air input to the oxygen concentrating system is liquefied natural gas. A first heat exchanger that exchanges heat between the first heat exchanger, a compressor that compresses air after heat exchange in the first heat exchanger to a predetermined pressure, and air that is compressed by the compressor A second heat exchanger that exchanges heat with liquefied natural gas, an expander that adiabatically expands the air heat-exchanged in the second heat exchanger, and an air that is adiabatically expanded by the expander A gas-liquid separation device that performs gas-liquid separation, and an electric motor that drives the compressor and the expander, and the compression ratio of the compressor and the expansion ratio of the expander are the temperatures of the air after the adiabatic expansion. Is higher than the boiling point of nitrogen and oxygen The compressor is a screw type compressor having a compression female rotor that is a screw rotor and a compression male rotor that is a screw rotor that meshes with the compression female rotor, The expander is a screw type expander having an expansion female rotor that is a screw rotor and an expansion male rotor that is a screw rotor meshing with the expansion female rotor, and the compression female rotor and the expansion female rotor are the same. The compression male rotor and the expansion male rotor are connected to each other so as to be integrally rotatable around an axis, and the electric motor is One rotating body including the compression female rotor and the expansion female rotor coupled thereto, the compression male rotor and the expansion male rotor coupled thereto Rotating at least one rotating body of a no other rotary member.

  This oxygen enrichment system can produce oxygen-enriched air in which the oxygen concentration of the air is increased rather than pure oxygen. Since oxygen-enriched air has a lower oxygen concentration than pure oxygen, the production of oxygen-enriched air in this oxygen enrichment system does not take extra costs required to increase the oxygen concentration to pure oxygen. For this reason, in this oxygen concentration system, the manufacturing cost of oxygen-enriched air can be suppressed compared with the manufacturing cost in the case of manufacturing pure oxygen.

  Moreover, in this oxygen concentrating system, the first heat exchanger and the second heat exchanger cooled the air by heat exchange using the cold heat of liquefied natural gas, and were cooled by the first heat exchanger. Oxygen-enriched air can be produced at low cost regardless of the production amount by compressing the subsequent air by the compressor.

  Specifically, by cooling the air using the cold energy of the liquefied natural gas that is vaporized, the power consumption for cooling the air can be suppressed regardless of the amount of oxygen-enriched air produced. it can. Further, by compressing the air after cooling by the compressor, the temperature of the air after adiabatic expansion can be made equal to or lower than the boiling point of oxygen even if the range of pressure increase (compression ratio) by the compressor is small. For this reason, the power consumption of the electric motor which drives a compressor can be suppressed. Since power consumption can be suppressed as described above, oxygen-enriched air can be produced at low cost regardless of the amount of oxygen-enriched air produced.

  In addition, this oxygen concentration system is not a quasi-static equilibrium process in which only oxygen is vaporized from liquefied air, such as a cryogenic separation system, but the oxygen in the air is liquefied and this air is separated into a gas-liquid separator Therefore, the oxygen concentration is continuously performed even if the amount of air supplied to the gas-liquid separation device fluctuates. For this reason, the production amount (production amount per unit time) of oxygen-enriched air can be changed.

  Furthermore, in this oxygen concentration system, since a screw type expander is used as means for adiabatically expanding the air after heat exchange in the second heat exchanger, heat exchange is performed in the second heat exchanger, for example. Energy consumption can be reduced compared to the case where an expansion valve is used as means for adiabatically expanding the subsequent air. Specifically, since the flow path becomes narrow at the location where the expansion valve is provided, frictional heat is generated between the air and the flow path wall in the process of adiabatic expansion, resulting in energy dissipation. On the other hand, in the screw type expander used in this oxygen concentration system, generation of frictional heat of air in the process of adiabatic expansion can be suppressed, and energy dissipation can be suppressed. As a result, the power consumption of the electric motor can be suppressed, and from this point, it is possible to manufacture oxygen-enriched air at a low cost.

  Moreover, in this oxygen concentration system, when the air compressed by the compressor is heat-exchanged by the second heat exchanger and then adiabatically expanded by the expander, the pneumatic energy (pressure) of the compressed air is expanded. It acts to rotate the female rotor and the expanding male rotor. Here, in the oxygen concentration system, the expansion female rotor and the compression female rotor are connected to each other so as to be integrally rotatable, and the expansion male rotor and the compression male rotor are integrally rotatable. Thus, the rotational force of the expansion female rotor due to the pneumatic energy is transmitted to the compression female rotor, and the rotational force of the expansion male rotor due to the pneumatic energy is transmitted to the compression male rotor. The For this reason, the electric power consumed in order that an electric motor rotates each rotor can be reduced significantly. Also from this point, it is possible to manufacture oxygen-enriched air at a low cost.

  In general, as an expander other than the screw expander, a turbine expander of a type that expands a target gas by rotating a turbine blade is known. Even in such a turbine expander, the generation of frictional heat of air in the process of adiabatic expansion can be suppressed. Therefore, it is theoretically assumed that the turbine expander is applied as the expander of the oxygen concentration system. In this case, if the rotating shaft of the turbine expander is connected to the screw rotor of the screw compressor, it is theoretically possible to regenerate the pneumatic energy of the compressed air from the turbine expander to the screw compressor.

  However, even if the flow rate of air flowing through the screw compressor and the turbine expander is the same, the rotational speed of the turbine expander is significantly different. It cannot be directly connected to the screw rotor. Temporarily, it may be possible to eliminate the difference in the number of operating revolutions between the rotating shaft of the turbine expander and the screw rotor of the screw compressor by eliminating the difference in the operating speed between them. Since energy is lost due to friction generated in the transmission, the energy regeneration effect is lost.

  In addition, when a turbine expander is applied as an expander of an oxygen concentration system, the screw compressor is changed to a turbine model imitating a turbine compressor used in a turbocharger added to an internal combustion engine of an automobile, for example. It is also conceivable to eliminate the difference in the operating rotational speed between the turbine expander and the turbine compressor. However, in a turbine compressor and a turbine expander, it is difficult to obtain a necessary compression ratio in the compressor unless the flow velocity of the air flowing through them is increased to rotate at high speed. If the motor is rotated at a high speed in order to obtain a necessary compression ratio, the heat generation amount of the motor becomes excessive and the cooling effect is impaired, so that the production cost of oxygen-enriched air increases. Further, if the flow velocity of air introduced into the expander is increased, frictional heat due to the air flow increases. In this case as well, the cooling effect is impaired, and the production cost of the oxygen-enriched air increases. Therefore, it is not realistic to use a turbine expander as an expander and a turbine compressor as a compressor in an oxygen concentration system.

  As described above, various alternative means for the screw compressor and the screw expander are theoretically conceivable, but there are problems in applying to the oxygen concentrating system. In the oxygen concentration system, it is most preferable to use a screw compressor and a screw expander.

  In the above-described oxygen concentration system, it is preferable that the expanded female rotor and the expanded male rotor have tooth shapes that prevent mutual contact when the rotors rotate together.

  According to such a configuration, when the expansion female rotor and the expansion male rotor rotate together, the mutual contact between the expansion female rotor and the expansion male rotor can be avoided to prevent the occurrence of frictional resistance due to the contact between the two rotors. it can. As a result, energy loss due to frictional resistance due to mutual contact between the expanded female rotor and the expanded male rotor can be prevented, and the power consumption of the motor can be further reduced.

  In this case, it is preferable that the compression female rotor and the compression male rotor have tooth shapes that prevent mutual contact when the rotors rotate together.

  According to such a configuration, when the compression female rotor and the compression male rotor rotate together, the mutual contact between the compression female rotor and the compression male rotor can be avoided to prevent the occurrence of frictional resistance due to the contact between the two rotors. it can. As a result, energy loss due to frictional resistance due to mutual contact between the compression female rotor and the compression male rotor can be prevented, and the power consumption of the motor can be further reduced.

  Moreover, in the above-described oxygen concentration system, the second heat exchanger is between the liquefied natural gas after heat exchange in the first heat exchanger and the air compressed by the compressor. A configuration in which heat exchange is performed is preferable.

  According to such a configuration, the liquefied natural gas whose temperature has been increased by heat exchange with air in the first heat exchanger can be further heated or vaporized in the second heat exchanger. That is, the temperature of the air discharged from the first heat exchanger is higher than that immediately after it is discharged from the first heat exchanger by being compressed by the compressor, so that the second heat exchanger Then, the liquefied natural gas can be further heated (heat exchanged) by the heat of the air to be heated or vaporized. Thereby, the cost of the energy (for example, electric power etc.) at the time of vaporizing in order to burn liquefied natural gas in various combustion facilities can be suppressed more.

  Moreover, in the above-described oxygen concentration system, the gas-liquid separation device is preferably a cyclone gas-liquid separation device that includes a separation cylinder extending in the vertical direction and rotates the supplied air within the separation cylinder.

  According to such a configuration, since the gas-liquid separation device has a simple structure in which the swirling flow of the air supplied in the separation cylinder is generated, the air at a very low temperature (temperature at which oxygen contained in the air is liquefied) Even if gas-liquid separation is performed, failure or the like hardly occurs. In addition, since the air is swirled in the separation cylinder, mist-like oxygen (liquefied oxygen) generated in the air can be continuously separated using centrifugal force.

  In the above-described oxygen concentration system, the first heat exchanger has a plurality of flow paths through which the liquefied natural gas or the air flows for heat exchange, and the first of the plurality of flow paths. It is preferable that the air flow in an outer flow path that is the flow path closest to the outside of one heat exchanger.

  According to such a configuration, the temperature gradient becomes monotonous from the outside to the inside of the first heat exchanger. That is, a temperature gradient in which the temperature decreases in the order of air, air flow path, and liquefied natural gas flow path without the temperature changing up and down from the outside to the inside of the first heat exchanger. Become. For this reason, while the heat insulation of a 1st heat exchanger improves, the thermal distortion in the said 1st heat exchanger can be suppressed.

  In this case, it is preferable that the first heat exchanger has an adsorbent containing zeolite disposed in the outer flow path or in a space communicating with the outer flow path in the first heat exchanger. .

According to such a configuration, when air passes through the first heat exchanger, water vapor, CO ₂ , methane, an organic solvent, and the like contained in the air are adsorbed by the adsorbent. Thereby, the fall of the gas-liquid separation efficiency in the gas-liquid separation apparatus resulting from these substances being contained in air can be prevented.

  Further, in the above-described oxygen concentration system, the second heat exchanger has a plurality of flow paths through which the liquefied natural gas or the air flows for heat exchange, and the second of the plurality of flow paths. It is preferable that the liquefied natural gas flows in an outer flow path that is the flow path closest to the outside of the second heat exchanger.

  In the heat exchanger, generally, the cross-sectional area of the outer flow path is larger than the cross-sectional area of the inner flow path that is provided inside the outer flow path and through which the fluid that exchanges heat with the fluid that flows through the outer flow path. For this reason, according to the above-described configuration, the liquefied natural gas is allowed to flow through the outer passage having a large cross-sectional area, and the second air having a reduced volume is caused to flow through the inner passage having a small cross-sectional area. The difference between the flow rate of liquefied natural gas and the flow rate of air (compressed air) in the heat exchanger is suppressed. Thereby, the fall of heat exchange efficiency can be suppressed.

  Furthermore, the expansion is achieved by absorbing the volume expansion caused by the vaporization of all or part of the liquefied natural gas by the heat exchange with the air whose temperature is increased by the heat generated by the compression in the compressor, by the difference in the cross-sectional area. Therefore, the stress generated in the second heat exchanger can be reduced.

  In this case, since the temperature of the liquefied natural gas flowing through the outer flow path is lower than the temperature of the air flowing through the inner flow path, it is caused by the temperature difference between the outside (outside air) and the inside of the second heat exchanger. In order to prevent the occurrence of thermal distortion, the second heat exchanger preferably has a heat insulating portion that surrounds the entire plurality of flow paths from the outside.

  In the above-described oxygen concentration system, any one of the liquefied natural gas after heat exchange in the first heat exchanger and the liquefied natural gas after heat exchange in the second heat exchanger is provided. A third gas that exchanges heat between one liquefied natural gas and the air separated in the gas-liquid separator and discharged from the gas-liquid separator and the exhaust gas exhausted from the facility that burns the natural gas. The heat exchanger may be further provided.

  According to such a configuration, by using exhaust gas (waste heat) generated in a facility that burns natural gas, liquefied natural gas (including gas that is partially gasified) supplied to the facility, and an oxygen concentration system Thus, the oxygen-enriched air produced by the method can be reliably vaporized (gasified). Moreover, since the exhaust gas exhausted from the facility for burning natural gas is exhaust gas after burning natural gas (high calorie combustion) in a state where oxygen-enriched air is supplied, its temperature is sufficiently high. For this reason, it is possible to reliably gasify both the liquefied natural gas (including the case where it is partially gasified) and the oxygen-enriched air supplied to the facility.

  Thus, in the oxygen concentration system configured to reliably vaporize liquefied natural gas and oxygen-enriched air supplied to the facility, a flow path through which air after heat exchange is performed in the third heat exchanger Or a generator disposed in a flow path through which the natural gas, which is a liquefied natural gas vaporized by heat exchange in the third heat exchanger, flows, and the generator includes the generator. It is preferable that power is generated using the flow or pressure of air or natural gas flowing through the flow path, and the generated power is supplied to the electric motor.

  According to such a configuration, it is possible to reduce the power supplied from the outside to the oxygen concentration system, and thereby to save power in the oxygen concentration system.

  The oxygen concentration system further includes a tank cooling flow path provided between a tank in which liquefied natural gas is stored and a heat insulating portion surrounding the outside of the tank, and the gas-liquid separation device includes the separated gas. Preferably, the exhaust part is connected to the tank cooling channel so that the gas to be exhausted flows to the tank cooling channel.

  According to this configuration, the tank can be cooled by using the cold heat of nitrogen or nitrogen-rich air at a very low temperature (below the boiling point of oxygen) exhausted from the exhaust section of the gas-liquid separator. As a result, the electric power required for cooling to maintain the liquefied natural gas stored in the tank in the liquid phase can be suppressed.

  Further, in the above-described oxygen concentration system, the oxygen concentration system further includes a guide channel that guides air introduced into the oxygen concentration system to the first heat exchanger, and the guide channel includes air that flows through the tank. It is preferable to arrange | position along the said tank so that heat exchange is possible between liquefied natural gas inside.

  According to such a configuration, by using the cold heat of the cryogenic liquefied natural gas stored in the tank, the air before being supplied to the first heat exchanger is cooled and condensed to form a rear stage (air flow It is possible to remove moisture in the air that causes a reduction in the gas-liquid separation efficiency in the gas-liquid separation device on the downstream side in FIG.

  In addition, it is possible to reduce the size of the first heat exchanger by cooling the air before being supplied to the first heat exchanger using the cold energy of the liquefied natural gas stored in the tank. Become.

  As mentioned above, according to this invention, while being able to change the production amount of oxygen enriched air, the oxygen enrichment system which can manufacture oxygen enriched air cheaply irrespective of the production amount can be provided.

1 is a diagram showing a schematic configuration of an oxygen enrichment system according to an embodiment of the present invention and a facility where the oxygen enrichment system is provided. It is a perspective view of a 1st heat exchanger. It is sectional drawing of the 1st heat exchanger in the III-III position of FIG. It is a figure which shows the relationship between the pressure of the air before and behind an expander, and the temperature of the air after expansion. It is a cross-sectional view of a compressor and an expander. It is a longitudinal cross-sectional view of the compressor and expander in the VI-VI position in FIG. It is sectional drawing of the compressor in the VII-VII position in FIG. It is a fragmentary sectional view which expands and shows the meshing part of the compression female rotor and compression male rotor during the steady operation of a compressor. It is a fragmentary sectional view which expands and shows the meshing part of these both rotors at the time of reverse rotation of a compression female rotor and a compression male rotor. It is sectional drawing of the expander in the XX position in FIG. It is a fragmentary sectional view which expands and shows the meshing part of an expansion female rotor and an expansion male rotor during steady operation. It is a fragmentary sectional view which expands and shows the meshing part of these both rotors at the time of reverse rotation of an expansion female rotor and an expansion male rotor. It is a cross-sectional view of a second heat exchanger. It is a top view of a cyclone type gas-liquid separation device. It is a front view of a cyclone type gas-liquid separation device. It is a cross-sectional view of a 3rd heat exchanger. It is a typical distribution diagram of the LNG thermal power plant by the 1st example to which the oxygen concentration system was applied. It is a typical systematic diagram of the superconducting LNG tanker by 2nd Example to which the oxygen concentration system was applied. It is a figure which shows schematic structure of the facility to which the oxygen concentration system which concerns on the modification of one Embodiment of this invention, and this oxygen concentration system are attached.

  Hereinafter, an oxygen concentration system according to an embodiment of the present invention will be described with reference to FIGS.

The oxygen concentration system according to the present embodiment (hereinafter also simply referred to as “concentration system”) concentrates oxygen in the input air to increase the oxygen concentration of the air. For example, the oxygen enrichment system of the present embodiment aims to improve thermal efficiency and reduce exhaust gas (CO ₂ gas, etc.) when natural gas (hereinafter also simply referred to as “NG”) is burned in a blast furnace, a power generation facility, or the like. It is used to produce air with a high oxygen concentration (oxygen-enriched air) to be blown in as Note that oxygen-enriched air is air having a higher oxygen concentration than the atmosphere. In the concentration system 10 of this embodiment, oxygen-enriched air having an oxygen concentration of about 30% is produced. In the present embodiment, NG is a gas (gas) obtained by vaporizing liquefied natural gas (hereinafter, also simply referred to as “LNG”).

  As shown in FIG. 1, the enrichment system 10 of the present embodiment stores LNG in a tank 50 and burns the gas (NG) vaporized from the LNG as fuel, for example, a facility 55 such as a blast furnace or a power generation facility. The oxygen-enriched air having an oxygen concentration higher than that of the air is produced from the input air using the cold heat of the LNG, and the produced oxygen-enriched air is supplied to the facility 55.

  The concentrating system 10 includes a blower 11, a precooling unit 12, a compressor 15, a second heat exchanger 16, an electric motor 17, an expander 18, a gas-liquid separator 19, and a third heat. An exchanger 20, a generator 21, and a drive circuit 22 are provided.

  The blower 11 sends (blows) air outside the concentration system 10 (atmosphere) to the precooling unit 12 as input air.

  The precooling unit 12 includes a dehumidification guide unit 13 and a first heat exchanger 14. The pre-cooling unit 12 cools the air sent by the blower 11. The dehumidifying guide unit 13 is an example of a guide channel according to the present invention.

  The dehumidifying guide unit 13 guides the air introduced into the concentration system 10 by the blower 11 to the first heat exchanger 14. The dehumidifying guide portion 13 is disposed along the tank 50 so that the air flowing through the dehumidifying guide portion 13 can exchange heat with the LNG stored in the tank 50. With such a configuration of the dehumidifying guide unit 13, the air before being supplied to the first heat exchanger 14 using the cold heat of LNG stored in the tank 50 at an extremely low temperature (113 K in this embodiment). It is possible to dehumidify the moisture inside by dew condensation in the dehumidifying guide section 13. As a result, it is possible to remove moisture in the air that causes a decrease in gas-liquid separation efficiency in the gas-liquid separation device 19 at the subsequent stage. In addition, it is possible to reduce the size of the first heat exchanger 14 by cooling the air before being supplied to the first heat exchanger 14.

  Specifically, the dehumidification guide unit 13 is connected to the blower 11 and the first heat exchanger 14. And the dehumidification guide part 13 guides the 1st heat exchanger 14, after letting the air (input air) supplied from the air blower 11 pass through the inside of the heat insulation wall 52. FIG. The heat insulating wall 52 is a wall that surrounds the tank 50 in which LNG is stored and is divided into a plurality of layers in the thickness direction. The dehumidifying guide unit 13 guides air to the first heat exchanger 14 after passing the air through the outermost layer of the heat insulating wall 52.

  In addition, the dehumidification guide part 13 is not limited to the structure which passes the injected air through the outermost layer of the heat insulation wall 52, It is comprised so that the other layer (layers other than the outermost layer) may be passed through. Also good. Moreover, in FIG. 1, the heat insulation wall 52 of several layers is simplified and described as a single layer wall.

  The first heat exchanger 14 exchanges heat between the air that has passed through the dehumidification guide 13 and the LNG supplied from the tank 50. The first heat exchanger 14 of the present embodiment is an aluminum plate fin heat exchanger as shown in FIGS. 2 and 3, for example. Specifically, the first heat exchanger 14 is a heat exchanger formed by brazing an aluminum member.

  The first heat exchanger 14 includes a box-shaped casing 140 and a heat exchanging unit 141 provided in the center of the casing 140. The heat exchange unit 141 includes a plurality of first flow paths 141a through which air flows and a plurality of second flow paths 141b through which LNG flows. The first flow path 141a and the second flow path 141b are alternately arranged in the heat exchange unit 141.

  The casing 140 has a lower header 142 and an upper header 143 for LNG at the lower end and the upper end. Moreover, the casing 140 has the upper side header 144 and the lower side header 145 for air in an upper part and a lower part.

  The heat exchanging part 141 is disposed at the center position in the vertical direction inside the casing 140. An upper distribution unit 146 is provided at the upper end of the heat exchange unit 141, and a lower distribution unit 147 is provided at the lower end of the heat exchange unit 141.

  The upper distributor 146 guides the air supplied from the dehumidifying guide 13 to the upper header 144 to each first flow path 141a of the heat exchange section 141 and passes through each second flow path 141b of the heat exchange section 141. The LNG is guided to the upper header 143. On the other hand, the lower distributor 147 guides the LNG supplied from the tank 50 to the lower header 142 to the second flow paths 141b of the heat exchange section 141 and passes through the first flow paths 141a of the heat exchange section 141. Air is guided to the lower header 145.

  With such a configuration, the air supplied to the first heat exchanger 14 sequentially passes through the upper header 144 and the upper distributor 146 and is introduced into each first flow path 141a of the heat exchanger 141. . Then, after passing through each first flow path 141a, this air sequentially passes through the lower distributor 147 and the lower header 145 and is discharged to the outside. On the other hand, LNG supplied to the first heat exchanger 14 passes through the lower header 142 and the lower distributor 147 in order, and is introduced into each second flow path 141b of the heat exchanger 141. The LNG passes through the second flow paths 141b, and then passes through the upper distributor 146 and the upper header 143 in order, and is discharged to the outside. In this way, LNG flows upward and air flows downward, so that heat exchange between LNG and air is performed via the aluminum plate that partitions the flow paths 141a and 141b. Done.

  In the heat exchange unit 141, the first flow paths 141a and the second flow paths 141b are alternately arranged, so that a large number of flow paths 141a and 141b are arranged in layers. The heat exchanging part 141 of the first heat exchanger 14 is arranged so that air flows through the outer flow path closest to the outside, specifically, the first flow path 141a at the right end and the first flow path 141a at the left end in FIG. It is configured. According to such a configuration, the outer periphery of the first heat exchanger 14 and the vicinity thereof in the stacking direction of the flow paths 141a and 141b (the left-right direction in FIG. 3) enter the first heat exchanger 14 from the outside. The temperature gradient becomes monotonous. Specifically, the temperature does not fluctuate up and down, and the temperature increases from the outside toward the inside of the first heat exchanger 14 in the order of the first flow path 141a through which air and air flow, and the second flow path 141b through which LNG flows. The temperature gradient becomes lower. For this reason, in the 1st heat exchanger 14, while improving heat insulation with the exterior, the thermal distortion in the said outer peripheral part of the said 1st heat exchanger 14 can be suppressed.

  In the heat exchanging part 141, the first channel 141a, which is the channel closest to the outside, has one layer more than the second channel 141b, so the total cross-sectional area of each first channel 141a is It is larger than the total cross-sectional area of each second flow path 141b.

In addition, an adsorbent (not shown) is disposed in the first flow path 141a of the first heat exchanger 14 or in the upper header 144 and the lower header 145 communicating with the first flow path 141a. Yes. The adsorbent of the present embodiment is made of zeolite such as molecular sieve, for example. This adsorbent adsorbs water vapor, CO ₂ , methane, organic solvent, and the like contained in the air when the air passes through the first heat exchanger 14. Thereby, the fall of the gas-liquid separation efficiency in the gas-liquid separation apparatus 19 resulting from these substances being contained in air can be prevented.

  The compressor 15 is connected to the first heat exchanger 14 and the second heat exchanger 16. The compressor 15 compresses the air after heat exchange in the first heat exchanger 14 to a predetermined pressure, and sends it out toward the second heat exchanger 16. The expander 18 is connected to the second heat exchanger 16 and the gas-liquid separator 19. The expander 18 adiabatically expands the air that has passed through the second heat exchanger 16 and has been introduced into the expander 18 and supplies the expanded air to the gas-liquid separator 19.

  The compressor 15 of this embodiment compresses the atmospheric pressure (1 atm) air supplied from the first heat exchanger 14 to 7 atm. That is, the compression ratio of the compressor 15 is 7.

  The compression ratio (compressed air pressure) is set so that the temperature of air after adiabatic expansion by the expander 18 is higher than the boiling point of nitrogen and lower than the boiling point of oxygen. Specifically, it is as follows.

The relationship between the pressures P ₁ and P ₂ of the air before and after the expander 18 and the temperatures T ₁ and T ₂ before and after the expander 18 is expressed by the following equation (1) from the Joule-Thomson relationship.

Cp is constant pressure specific heat, and Cv is constant volume specific heat. The temperature _{T 1} of the air before the adiabatic expansion in the present embodiment is 113K.

  FIG. 4 is a graph showing this relationship. In the said concentration system 10, since it is necessary to supply air as a high-speed gas flow with respect to the gas-liquid separator 19 from the expander 18, it is necessary to ensure 3 atmospheres as the pressure of the air after adiabatic expansion. Therefore, referring to FIG. 4, if the pressure of air before adiabatic expansion (that is, the pressure of air immediately before the expander) is 7 atm or higher, the temperature of the air after adiabatic expansion is higher than the boiling point of nitrogen and oxygen. Or less than the boiling point. Moreover, it turns out that 3 atmospheres can be ensured in the air after adiabatic expansion.

  The expander 18 of the present embodiment adiabatically expands the supplied air so that the temperature of the air is higher than the boiling point of nitrogen (77K) and lower than the boiling point of oxygen (90K). That is, the expansion ratio of the expander 18 is set so that the temperature of the adiabatic expanded air is higher than the boiling point of nitrogen and lower than the boiling point of oxygen. Thereby, the air that has passed through the expander 18 is in a state in which oxygen in the air has been liquefied (specifically, air containing mist-like oxygen).

  In the expander 18 of the present embodiment, the number of turns of the teeth 182a and 183a of the screw rotors 182 and 183 (described later) is set according to the pressure and temperature of the air before adiabatic expansion. Further, the expander 18 of the present embodiment forms a swirl flow that can be separated into gas and liquid in the gas-liquid separator 19 so that air can be supplied to the gas-liquid separator 19 at a flow rate equal to or higher than a predetermined value. The air pressure after adiabatic expansion is designed to be 3 atm so that air can be supplied to the gas-liquid separator 19 at such a flow rate.

  Hereinafter, specific structures of the compressor 15 and the expander 18 will be described.

  The compressor 15 is a screw type compressor that is a type of positive displacement compressor, and the expander 18 is a screw type expander that is a type of positive displacement type expander. As shown in FIG. 5, the compressor 15 includes a pair of male and female screw rotors 156 and 157 that mesh with each other, and the expander 18 includes a pair of male and female screw rotors 182 and 183 that mesh with each other.

  The compressor 15 and the expander 18 include a common integrated casing 150. In this casing 150, the screw rotors 156 and 157 of the compressor 15 and the screw rotors 182 and 183 of the expander 18 are accommodated so as to be rotatable. Hereinafter, the female rotor 156 that is one of the pair of screw rotors 156 and 157 of the compressor 15 is referred to as a compression female rotor 156, and the male rotor 157 that is the other screw rotor is referred to as a compression male rotor 157. . The female rotor 182 that is one screw rotor of the pair of screw rotors 182 and 183 of the expander 18 is referred to as an expansion female rotor 182, and the male rotor 183 that is the other screw rotor is referred to as an expansion male rotor 183. .

  The compression female rotor 156 and the expansion female rotor 182 share an intermediate rotor shaft 158 therebetween, and the compression male rotor 157 and the expansion male rotor 183 share an intermediate rotor shaft 166 therebetween. Yes. That is, the compression female rotor 156 and the expansion female rotor 182 are arranged coaxially so as to be integrally rotatable about the same rotation axis and are connected to each other via the rotor shaft 158. The compression male rotor 157 and the expansion male rotor 183 are arranged coaxially so as to be integrally rotatable around the same rotation axis and are connected to each other via the rotor axis 166. With this configuration, in the present embodiment, the compressor 15 and the expander 18 are not operated independently of each other but are operated in conjunction with each other.

  A rotor shaft 161 is provided so as to extend from the expansion female rotor 182 to the opposite side of the compression female rotor 156, and a rotor shaft 163 is provided so as to extend from the compression female rotor 156 to the opposite side of the expansion female rotor 182. One rotor shaft 161 is supported to be rotatable by a corresponding bearing 162 provided in the casing 150, and the other rotor shaft 163 is rotatable by a corresponding bearing 164 provided in the casing 150. It is supported to become.

  A rotor shaft 167 is provided so as to extend from the expansion male rotor 183 to the opposite side to the compression male rotor 157, and a rotor shaft 169 is provided so as to extend from the compression male rotor 157 to the opposite side of the expansion male rotor 183. One rotor shaft 167 is supported so as to be rotatable by a corresponding bearing 168 provided in the casing 150, and the other rotor shaft 169 is rotatable by a corresponding bearing 170 provided in the casing 150. It is supported to become. The rotating body composed of the compression female rotor 156, the expansion female rotor 182 and the rotor shafts 158, 161 and 163, and the rotation body composed of the compression male rotor 157, the expansion male rotor 183 and the rotor shafts 166, 167 and 169 are the rotors thereof. The shafts 158, 161, 163 and the rotor shafts 166, 167, 169 are arranged so as to be parallel to each other.

  In the present embodiment, an electric motor 17 that drives the compressor 15 and the expander 18 is provided in the casing 150. The electric motor 17 rotates a rotating body including a compression male rotor 157, an expansion male rotor 183, and rotor shafts 166, 167, and 169. The electric motor 17 has a rotating part 17a and a fixed part 17b.

  The rotating portion 17 a is provided on a rotor shaft 166 that connects the rotors between the compression male rotor 157 and the expansion male rotor 183. The rotating portion 17a is disposed so as to be coaxial with the compression male rotor 157, the expansion male rotor 183, and the rotor shafts 166, 168, and 169.

  The fixed portion 17 b is disposed so as to surround the radially outer side of the rotating portion 17 a and is fixed in the casing 150. The rotating portion 17a can rotate integrally with the rotor shaft 166 inside the fixed portion 17b.

  The electric motor 17 is electrically connected to the drive circuit 22. When the electric power is supplied from the drive circuit 22, the electric motor 17 rotates the rotating portion 17 a with respect to the fixed portion 17 b, thereby rotating the rotor shaft 166. Thereby, the rotary body which consists of the compression male rotor 157, the expansion male rotor 183, and the rotor shafts 166, 167, and 169 rotates.

  In the electric motor 17, as a load for driving the electric motor 17, the work regenerated by the expansion of the air by the expander 18 is subtracted from the work necessary for rotating the rotors 156 and 157 of the compressor 15 to compress the air. The load corresponding to the value is applied. If the expansion female rotor 182 and the expansion male rotor 183 are meshed with each other in contact with each other, the dissipated energy caused by the friction between the expansion female rotor 182 and the expansion male rotor 183 is not limited to the load. 17 cannot be ignored as a factor of the load applied to 17.

  If the environment is higher than room temperature, the friction between the male rotor and the female rotor is reduced by the lubricating oil filled in the expander and the liquid phase part of the vapor refrigerant liquefied. For this reason, even when the teeth of the male rotor and the teeth of the female rotor of the expander are in contact with each other during the operation of the expander, the dissipated energy due to the friction caused by the contact is suppressed.

  However, in the concentration system 10 of the present embodiment, since it is in an extremely low temperature (113K) environment, there is no lubricating oil that can exhibit lubricity in that environment, and it is introduced into the expander 18. Since air is a mixed gas of nitrogen and oxygen, lubricity between the expanded female rotor 182 and the expanded male rotor 183 cannot be expected.

  Therefore, in this embodiment, the expansion female rotor 182 and the expansion male rotor 183 have tooth shapes that prevent mutual contact when the rotors rotate together while meshing with each other. That is, the expanded female rotor 182 and the expanded male rotor 183 have tooth shapes that maintain a minute gap between the tooth surfaces (outer surfaces) of the rotors 182 and 183 when rotating. Hereinafter, the tooth profile of the compression female rotor 156 and the compression male rotor 157 and the tooth profile of the expansion female rotor 182 and the expansion male rotor 183 will be described in detail.

The compression female rotor 156 and the compression male rotor 157 are engaged with each other as shown in FIG. FIG. 7 shows a cross section orthogonal to the axial direction of the compression female rotor 156 and the compression male rotor 157. 8 is an enlarged view of a meshing portion between the compression female rotor 156 and the compression male rotor 157 during the steady operation of the compressor 15, and FIG. 9 is a reverse view of the compression female rotor 156 and the compression male rotor 157. The meshing part between the two rotors during rotation is shown enlarged. 7 to 9, O ₁ indicates the rotation center (rotation axis) of the compression male rotor 157, and O ₂ indicates the rotation center (rotation axis) of the compression female rotor 156.

  During the steady operation of the compressor 15, the tooth surface on the front side in the rotation direction of the rotor (the arrow direction in FIG. 8) of the teeth 157 a of the compression male rotor 157 is the teeth facing the teeth 156 a of the compression female rotor 156. A rotational force is transmitted by contacting the surface and pushing the tooth 156a. That is, in the portion X in FIG. 8, the rotational force is transmitted from the teeth 157a of the compression male rotor 157 to the teeth 156a of the compression female rotor 156. Thereby, the compression male rotor 157 and the compression female rotor 156 rotate together in synchronization.

  On the other hand, for example, when the driving of the compressor 15 is stopped, the compression female rotor 156 and the compression male rotor 157 may rotate in reverse due to the pressure of the compressed air. In that case, there is a possibility that the tooth surface of the tooth 157a of the compression male rotor 157 on the front side in the reverse rotation direction (arrow direction in FIG. 9) of the rotor contacts the tooth surface of the compression female rotor 156 facing the tooth 156a. is there. That is, there is a possibility that the tooth 157a of the compression male rotor 157 contacts the tooth 156a of the compression female rotor 156 in the Y portion in FIG.

Further, the expansion female rotor 182 and the expansion male rotor 183 are engaged with each other as shown in FIG. FIG. 10 shows a cross section orthogonal to the axial direction of the expansion female rotor 182 and the expansion male rotor 183. FIG. 11 is an enlarged view of the meshing portion between the expansion female rotor 182 and the expansion male rotor 183 during steady operation, and FIG. 12 shows both of the expansion female rotor 182 and the expansion male rotor 183 at the time of reverse rotation. The meshing portion between the rotors is shown enlarged. 10 to 12, O ₃ indicates the rotation center (rotation axis) of the expansion male rotor 183, and O ₄ indicates the rotation center (rotation axis) of the expansion female rotor 182.

  In this embodiment, the expansion female rotor 182 has the same tooth profile as the compression female rotor 156. On the other hand, the teeth 183a of the expansion male rotor 183 are formed in a shape in which the portions corresponding to the X portion and the Y portion of the teeth 157a of the compression male rotor 157 are removed.

  Specifically, of the teeth 183a of the expansion male rotor 183, the front portion in the rotational direction (in the direction of the arrow in FIG. 11) during normal operation, which is in contact with the tooth surface facing the corresponding tooth 182a of the expansion female rotor 182 The C1 portion that has the possibility of Further, of the teeth 183 a of the expansion male rotor 183, the front portion of the expansion male rotor 183 in the reverse rotation direction (the arrow direction in FIG. 12) and the tooth surface facing the corresponding tooth 182 a of the expansion female rotor 182. The C2 portion that may be contacted is removed. With such a configuration, the teeth 183a of the expansion male rotor 183 are prevented from coming into contact with the expansion female rotor 182 during both steady operation and reverse rotation.

  The casing 150 includes a rotating body including a compression female rotor 156, an expansion female rotor 182 and rotor shafts 158, 161, and 163, and a rotation body including a compression male rotor 157, expansion male rotor 183, and rotor shafts 166, 167, and 169. Surrounding. The casing 150 is cooled by LNG and maintained at 113K, which is the temperature of the LNG.

  Note that the lubricating oil cannot be used for lubricating the bearings 162, 164, 168, and 170 in the casing 150 because the casing 150 is maintained at such an extremely low temperature (113 K). This is because there is generally no liquid lubricating oil that can maintain a low viscosity at such an extremely low temperature. Therefore, in the present embodiment, each of the bearings 162, 164, 168, and 170 is a sliding bearing formed of a material such as Teflon (registered trademark), and is discharged from the gas-liquid separator 19 as described later. By supplying oxygen-enriched air containing liquid oxygen from the unit 195, the liquid oxygen in the oxygen-enriched air is vaporized, and the bearings 162, 164, 168, and 170 function as a kind of air bearing. As a result, the occurrence of wear at each of the bearings 162, 164, 168, 170 is suppressed without using lubricating oil.

  As shown in FIG. 6, a compressor suction port 151 and a compressor discharge port 152 are formed in a portion of the casing 150 corresponding to the compressor 15. Further, an expander suction port 153 and an expander discharge port 154 are formed in a portion corresponding to the expander 18 in the casing 150. The compressor suction port 151 is connected to the lower header 145 (see FIG. 2) of the first heat exchanger 14. The compressor discharge port 152 is connected to the second heat exchanger 16 (see FIG. 1). The expander suction port 153 is connected to the second heat exchanger 16 (see FIG. 1). The expander discharge port 154 is connected to the gas-liquid separator 19 (see FIG. 1).

  Air discharged from the lower header 145 of the first heat exchanger 14 is sucked into the compressor 15 through the compressor suction port 151. The air sucked into the compressor 15 is introduced into a gas confinement space formed between the compression female rotor 156 and the compression male rotor 157 and the inner surface of the casing 150, and the compression female rotor 156 and the compression male rotor. As 157 rotates in the opposite direction and the gas confinement space is reduced, it is compressed. At this time, the compression male rotor 157 rotates clockwise in FIG. 7, and the compression female rotor 156 rotates counterclockwise in FIG. The compressed air is discharged from the compressor discharge port 152 (see FIG. 6), and is supplied to the expander suction port 153 (see FIG. 6) through the second heat exchanger 16 (see FIG. 1).

  Air sucked into the expander 18 through the expander suction port 153 is trapped in the space formed between the expansion female rotor 182 and the expansion male rotor 183 and the inner surface of the casing 150. The expansion male rotor 183 is rotated integrally with the compression male rotor 157 by the electric motor 17, and the expansion female rotor 182 is rotated integrally with the compression female rotor 156, whereby the expansion male rotor 183 and the expansion female rotor are rotated. 182 rotate in opposite directions. At this time, the expansion male rotor 183 rotates clockwise in FIG. 10, and the expansion female rotor 182 rotates counterclockwise in FIG. The space between the expansion female rotor 182 and the expansion male rotor 183 and the inner surface of the casing 150 is expanded by the rotation of the expansion male rotor 183 and the expansion female rotor 182, and the air trapped in the space is expanded. The expanded air is discharged from the expander discharge port 154 (see FIG. 6) and supplied to the gas-liquid separator 19 (see FIG. 1).

  Since the air confined in the space between the expansion female rotor 182 and the expansion male rotor 183 and the inner surface of the casing 150 is air compressed by the compressor 15 as described above, the pneumatic energy (pressure) of the air is compressed. Acts in the direction of expanding the space between the expansion female rotor 182 and the expansion male rotor 183 and the inner surface of the casing 150. For this reason, a force that rotates the rotors 182 and 183 in the opposite directions acts on the expansion female rotor 182 and the expansion male rotor 183 from this air. Since this force is transmitted to the compression female rotor 156 connected to the expansion female rotor 182 and the compression male rotor 157 connected to the expansion male rotor 183, the power for rotating the compression male rotor 157 and the compression female rotor 156 Contribute as. In this way, the pneumatic energy generated by the compression of air in the compressor 15 is regenerated, and the power consumption of the electric motor 17 is greatly reduced. For example, when such energy regeneration is not performed, the power consumption is reduced to 50% or less of the power consumption when the electric motor 17 rotates the compression male rotor 157 and the compression female rotor 156.

  The second heat exchanger 16 (see FIG. 1) is configured to exchange the compressed air supplied from the compressor 15 and the LNG supplied from the first heat exchanger 14 (heat exchange in the first heat exchanger 14). Heat exchange with the LNG after being partly vaporized and including NG. The second heat exchanger 16 of the present embodiment is an aluminum plate fin heat exchanger.

  As shown in FIG. 13, the second heat exchanger 16 is configured in the same manner as the first heat exchanger 14 except that a heat insulating portion 160 is provided outside the casing 140. The heat insulating portion 160 has a vacuum heat insulating structure.

  The second heat exchanger 16 is connected to the first heat exchanger 14 and the compressor 15 so that LNG flows through the first flow path 141a and air flows through the second flow path 141b. Yes. Since LNG having a low temperature flows through the outermost channel (outer channel) in this way, by providing the heat insulating portion 160, the outside (outside air) and the inside (first air) in the outer peripheral portion of the second heat exchanger 16 are provided. Generation of thermal distortion due to a temperature difference from LNG) flowing through the flow path 141a is prevented.

  In the second heat exchanger 16, as in the first heat exchanger 14, the total cross-sectional area of each first flow path 141 a (the cross-sectional area of the cross section orthogonal to the flow direction) is the second flow flow. It is larger than the sum of the cross-sectional areas of the passage 141b (the cross-sectional area of the cross section orthogonal to the flow direction). Therefore, like the second heat exchanger 16, LNG is passed through the first flow path 141a having a large total cross-sectional area of each flow path, and the second flow path having a small total cross-sectional area of each flow path. By flowing the air that has been compressed to 141b and has a reduced volume, the difference in flow velocity between the LNG flowing in the second heat exchanger 16 and the air (compressed air) can be suppressed. Thereby, the fall of the heat exchange efficiency in the 2nd heat exchanger 16 is suppressed.

  Furthermore, by absorbing the volume expansion due to the vaporization of all or part of the LNG by heat exchange with the air whose temperature has risen due to heat generated by the compression in the compressor 15, the second cross section can be absorbed. The stress based on the expansion generated in the heat exchanger 16 can be reduced.

  The gas-liquid separator 19 (see FIG. 1) is air that has been adiabatically expanded by the expander 18 and has a temperature that is higher than the boiling point of nitrogen and lower than or equal to the boiling point of oxygen (in this embodiment, oxygen is mist-like). Gas-liquid separation. In the present embodiment, a cyclone gas-liquid separator as shown in FIGS. 14 and 15 is used as the gas-liquid separator 19.

  The gas-liquid separator 19 includes a separation cylinder 190 that extends vertically. The gas-liquid separator 19 rotates the supplied air in the separation cylinder 190. That is, the gas-liquid separation device 19 of the present embodiment forms a swirling flow of supplied air in the separation cylinder 190, and performs so-called cyclone type gas separation that performs gas-liquid separation using centrifugal force in the swirling flow. Perform liquid separation.

  The separation cylinder 190 has a cylindrical cylindrical upper portion 191 centering on an axis c extending in the vertical direction, and a conical cylindrical lower portion 192 provided on the lower side of the cylindrical upper portion 191. The cylindrical upper portion 191 includes an introduction port 193 connected to the compressor 15 and provided at the upper end portion of the cylindrical upper portion 191, and a discharge cylinder 194 extending vertically so as to penetrate the center portion of the top wall of the cylindrical upper portion 191. Have.

  In the separation cylinder 190, air containing mist-like oxygen is introduced from the introduction port 193 into the cylinder upper portion 191 in a tangential direction. The introduced air turns into a swirling flow that goes downward while swirling along the inner peripheral surface 191 a of the cylindrical upper portion 191. Due to the centrifugal force in the swirl flow, liquefied oxygen (mist-like oxygen) adheres to the inner peripheral surfaces 191a and 192a of the separation cylinder 190, and flows downward along the inner peripheral surfaces 191a and 192a.

  The flow of air from which the mist-like (liquefied) oxygen has been removed by centrifugal force during the rotation from the cylindrical upper part 191 to the cylindrical lower part 192 (that is, nitrogen or nitrogen-rich air) flows. In 192, the flow flows upward, and is discharged to the outside from a discharge cylinder 194 provided at the center of the cylinder upper portion 191. If the inclination angle with respect to the central axis (vertical axis) c of the inner peripheral surface 192a of the cylindrical lower portion 192 is too large, air is rolled up together with the mist and discharged from the discharge cylinder 194, while if the inclination angle is too small, The length dimension of the separation cylinder 190 in the vertical direction is increased. For this reason, the inclination angle is preferably 75 ° to 85 °.

  A discharge portion 195 for discharging the liquid (mist-like oxygen) separated in the gas-liquid separation device 19 is provided at the lower end of the cylindrical lower portion 192. The discharge unit 195 includes a liquefied oxygen receiving unit (not shown) and a drain pump 196 (see FIG. 1). The liquefied oxygen receiver stores mist-like oxygen that has flowed down along the inner peripheral surfaces 191a and 192a of the separation cylinder 190. The drainage pump 196 continuously or intermittently discharges the liquid (mist-like oxygen) accumulated in the liquefied oxygen receiver. In this embodiment, the drainage pump 196 discharges the air accumulated in the liquefied oxygen receiving portion in the form of bubbles to the outside. The foamy air discharged by the drain pump 196 is oxygen-enriched air enriched with oxygen.

  In the case where liquefied oxygen (bubble air) accumulated in the liquefied oxygen receiver is intermittently discharged to the outside, an electromagnetic valve may be provided instead of the drain pump 196.

  The discharge unit 195 is connected to the third heat exchanger 20. Further, the discharge unit 195 includes bearings 162, 164 and the like that support a rotating body including the compression female rotor 156 and the expansion female rotor 182 through the flow path 197, and a rotation body including the compression male rotor 157 and the expansion male rotor 183. Are connected to bearings 168, 170, and the like. With these configurations, the oxygen-enriched air discharged from the discharge unit 195 is supplied to the third heat exchanger 20, the bearings 162, 164, 168, 170, and the like.

  Since the separation cylinder 190 needs to hold the air swirling inside so that its temperature is higher than the boiling point of nitrogen (77K) and lower than the boiling point of oxygen (90K), the peripheral wall has a vacuum heat insulating structure. ing. Moreover, in order to suppress the friction between the swirling flow of air and the inner peripheral surfaces 191a and 192a, the inner peripheral surfaces 191a and 192a are mirror-finished.

  The discharge cylinder 194 is an example of the exhaust part of the present invention. The discharge cylinder 194 is connected to a tank cooling channel 54 provided between the tank 50 and a heat insulating wall 52 surrounding the outside of the tank 50. Thereby, nitrogen (or nitrogen-rich air) discharged from the discharge cylinder 194 is supplied to the tank cooling channel 54. Since this nitrogen is an extremely low temperature below the boiling point of oxygen, by cooling the LNG stored in the tank 50 by the cold heat of this nitrogen, the electric power for maintaining the temperature of the LNG in the tank 50 is suppressed. be able to. In the present embodiment, nitrogen after cooling the tank 50 is released into the atmosphere.

  The third heat exchanger 20 (see FIG. 1) is configured to supply oxygen-enriched air discharged from the discharge unit 195 of the gas-liquid separator 19 and LNG (NG-liquid two containing NG) that has passed through the second heat exchanger 16. LNG) or NG in the phase state and the exhaust gas exhausted from the facility 55 are subjected to heat exchange. The third heat exchanger 20 of the present embodiment is an aluminum plate fin heat exchanger. As shown in FIG. 16, the third heat exchanger 20 is configured in the same manner as the first heat exchanger 14.

  The third heat exchanger 20 is configured such that exhaust gas flows through the first flow path 141a, and oxygen-enriched air and LNG (or NG) flow alternately through the second flow path 141b (141c). . In addition, in FIG. 16, the code | symbol of the 2nd flow path through which oxygen-enriched air flows is 141b, and the code | symbol of the 2nd flow path through which LNG (or NG) flows is 141c.

  In the facility 55, NG is burned while supplying oxygen-enriched air (high-calorie combustion is performed), so high-temperature exhaust gas is discharged. In the third heat exchanger 20, the oxygen-enriched air and NG are completely vaporized by exchanging heat with the high-temperature exhaust gas.

  The generator 21 (see FIG. 1) is disposed downstream of the third heat exchanger 20 and generates power using the air discharged from the third heat exchanger 20. Specifically, the generator 21 is a turbine generator including a turbine, and is disposed in a flow path of oxygen-enriched air supplied from the third heat exchanger 20 to the facility 55. The generator 21 generates power by rotating the turbine with the flow of oxygen-enriched air toward the facility 55. The generator 21 is connected to the drive circuit 22 so that power can be transmitted, and supplies the generated power to the drive circuit 22.

  The drive circuit 22 controls driving of the electric motor 17 by controlling power transmission to the electric motor 17. Therefore, the electric power generated by the generator 21 is supplied to the electric motor 17 via the drive circuit 22. Thereby, the electric power supplied to the said concentration system 10 from the outside can be suppressed, As a result, the power saving of the said concentration system 10 can be achieved.

  The generator 21 is not limited to a turbine generator that generates power using the flow of oxygen-enriched air, but a generator that generates power using the pressure of oxygen-enriched air (for example, so-called screw-type power generation). Machine).

  In addition, when the LNG that has exchanged heat with air (compressed air) in the second heat exchanger 16 is exhausted from the second heat exchanger 16 in a completely vaporized state (NG state), power generation The machine 21 may be disposed on a flow path connecting the second heat exchanger 16 and the third heat exchanger 20.

  According to the concentration system 10 according to the present embodiment as described above, it is possible to produce oxygen-enriched air in which the oxygen concentration of air is increased instead of pure oxygen. Since oxygen-enriched air has a lower oxygen concentration than pure oxygen, the production of oxygen-enriched air does not take extra costs required to increase the oxygen concentration to pure oxygen. For this reason, in the concentration system 10 of this embodiment, the manufacturing cost of oxygen-enriched air can be suppressed compared with the manufacturing cost in the case of manufacturing pure oxygen.

  Moreover, in the concentration system 10 of the present embodiment, the first heat exchanger 14 and the second heat exchanger 16 cool the air by heat exchange using the cold heat of LNG, and the first heat exchanger 14. When the compressor 15 compresses the air that has been cooled in step 1, the oxygen-enriched air can be manufactured at low cost regardless of the production amount.

  Specifically, by cooling the air using the cold heat of LNG used after being vaporized, power consumption for cooling the air can be suppressed regardless of the production amount of oxygen-enriched air. Further, the compressor 15 compresses the air after cooling, so that the temperature of the air after adiabatic expansion can be made equal to or lower than the boiling point of oxygen even if the pressure increase range (compression ratio) by the compressor 15 is small. For this reason, the power consumption in the compressor 15 can be suppressed. Since power consumption can be suppressed as described above, oxygen-enriched air can be produced at low cost regardless of the amount of oxygen-enriched air produced.

  Further, in the concentration system 10 of the present embodiment, this air is not a quasi-static equilibrium process in which only oxygen is vaporized from liquefied air as in the conventional cryogenic separation system, but oxygen in the air is liquefied. Since the gas-liquid separation device 19 forcibly gas-liquid separates the oxygen concentration, the oxygen concentration is performed even if the amount of air supplied to the gas-liquid separation device 19 fluctuates. Is performed continuously. Therefore, the production amount of oxygen-enriched air (production amount per unit time) can be changed.

  Further, in the concentration system 10 of the present embodiment, the gas-liquid separation device 19 is a device having a simple structure in which the swirling flow of the supplied air is generated in the separation cylinder 190. Even if air-liquid separation of air at a temperature at which oxygen contained is liquefied (90K or less) is performed, failure or the like hardly occurs. Moreover, since the air is swirled in the separation cylinder 190, mist-like oxygen (liquefied oxygen) generated in the air can be continuously separated using centrifugal force.

  Furthermore, in the concentration system 10 of this embodiment, since the screw type expander 18 is used as means for adiabatically expanding the air after heat exchange in the second heat exchanger 16, for example, the second heat exchanger As compared with a case where an expansion valve is used as means for adiabatically expanding the air after heat exchange in 16, energy consumption can be reduced. Specifically, since the flow path becomes narrow at the location where the expansion valve is provided, frictional heat is generated between the air and the flow path wall in the process of adiabatic expansion, resulting in energy dissipation. On the other hand, in the screw type expander 18 used in the concentration system 10 of the present embodiment, generation of frictional heat of air in the process of adiabatic expansion can be suppressed, and energy dissipation can be suppressed. As a result, energy consumption can be reduced.

  In the concentration system 10 of the present embodiment, when the air compressed by the compressor 15 is heat-exchanged by the second heat exchanger 16 and then adiabatically expanded by the expander 18, the air pressure of the compressed air Energy (pressure) acts to rotate the expansion female rotor 182 and the expansion male rotor 183. In the concentration system 10 of the present embodiment, the expansion female rotor 182 and the compression female rotor 156 are connected to each other so as to be integrally rotatable, and the expansion male rotor 183 and the compression male rotor 157 are integrated. Are connected to each other so as to be rotatable, the rotational force of the expansion female rotor 182 caused by the pneumatic energy is transmitted to the compression female rotor 156, and the expansion male rotor 183 caused by the pneumatic energy is transmitted. The rotational force is transmitted to the compression male rotor 157. For this reason, the electric power consumed in order that the electric motor 17 rotates each rotor can be reduced significantly.

  In general, as an expander other than the screw expander, a turbine expander of a type that expands a target gas by rotating a turbine blade is known. Even in such a turbine expander, generation of frictional heat of air in the process of adiabatic expansion can be suppressed, so that it is theoretically assumed that the turbine expander is applied as the expander 18 according to the present embodiment. In this case, if the rotating shaft of the turbine expander is connected to the screw rotor of the compressor 15 via the rotor shaft, it is theoretically possible to regenerate the pneumatic energy of the compressed air from the turbine expander to the compressor 15. It is.

  However, the screw-type compressor 15 and the turbine expander have a significantly different operating rotational speed even if the flow rate of air flowing through them is the same, so that the rotating shaft of the turbine expander is connected to the compressor 15. It cannot be directly connected to the screw rotor. Temporarily, a transmission may be interposed between the rotating shaft of the turbine expander and the screw rotor of the compressor 15 to eliminate the difference in operating speed between them. Since energy is lost due to friction generated in the machine, the energy regeneration effect is lost.

  Further, when a turbine expander is applied as the expander 18, the compressor 15 is replaced with, for example, a turbine type imitating a turbine compressor used in a supercharger (turbocharger) added to an internal combustion engine of an automobile. It is also conceivable to eliminate the difference in the operating rotational speed between the turbine expander and the turbine compressor by changing. However, in a turbine compressor and a turbine expander, it is difficult to obtain a necessary compression ratio in the compressor unless the flow velocity of the air flowing through them is increased to rotate at high speed.

  If the electric motor 17 is rotated at a high speed in order to obtain a necessary compression ratio, the heat generation amount of the electric motor 17 becomes excessive and the cooling effect is impaired, so that the production cost of oxygen-enriched air increases. Further, if the flow rate of air introduced into the expander 18 is increased, frictional heat due to the air flow increases. In this case as well, the cooling effect is impaired, and the production cost of the oxygen-enriched air increases. Therefore, it is not realistic to use a turbine expander as the expander 18 and a turbine compressor as the compressor 15 in the oxygen concentration system.

  As described above, various alternative means for the screw-type compressor 15 and the expander 18 according to the present embodiment are theoretically conceivable. In the oxygen concentration system 10 of this embodiment, it is most preferable to use the screw type compressor 15 and the expander 18.

  Further, in the concentration system 10 of the present embodiment, the expansion female rotor 182 and the expansion male rotor 183 have tooth shapes that avoid mutual contact when the rotors rotate together. Generation of frictional resistance due to mutual contact with the expansion male rotor 183 can be prevented. As a result, energy loss due to frictional resistance due to mutual contact between the expanded female rotor 182 and the expanded male rotor 183 can be prevented, and the power consumption of the electric motor 17 can be further reduced.

(First embodiment)
Next, an LNG thermal power plant will be described as a first example to which the oxygen concentration system of the above embodiment is applied. The LNG thermal power plant according to the first embodiment (hereinafter, simply referred to as “power plant”) combusts natural gas generated by gasification of LNG generated in the production of oxygen-enriched air in the oxygen enrichment system, This is a method of generating power by using energy obtained by combustion. FIG. 17 shows a schematic system diagram of the power plant according to the first embodiment.

  The power plant according to the first embodiment includes a superconducting generator 25, a turbine 26, a reformer 27, and a combustion boiler 28.

  The superconducting generator 25 is connected to the drive shaft of the turbine 26, and generates power when the power of the turbine 26 is transmitted. The superconducting generator 25 includes a superconducting coil using an oxide-based superconducting wire material such as Bi-based or Y-based that undergoes a superconducting transition at the temperature of liquid nitrogen. The superconducting generator is electrically connected to the drive circuit 22 and supplies the generated power to the drive circuit 22. The drive circuit 22 supplies the electric power supplied from the superconducting generator 25 to the electric motor 17.

  The reformer 27 is disposed downstream of the third heat exchanger 20 and reforms the natural gas discharged from the third heat exchanger 20.

  The combustion boiler 28 corresponds to a facility for burning natural gas. The combustion boiler 28 is supplied with natural gas reformed by the reformer 27 and oxygen-enriched air discharged from the third heat exchanger 20. The combustion boiler 28 generates high-temperature steam by combustion using the supplied natural gas and oxygen-enriched air, and supplies the generated steam to the turbine 26. The turbine 26 is driven by this steam, and the superconducting generator 25 generates power as described above.

  Further, in the power plant according to the first example, a configuration including the compressor 15, the first heat exchanger 16, the expander 18, the electric motor 17, and the gas-liquid separator 19 of the oxygen concentration system of the above embodiment is provided in two stages. It has been. The discharge cylinder 194 of the first-stage gas-liquid separator 19 is connected to the compressor suction port 151 of the second-stage compressor 15 and is discharged from the discharge cylinder 194 of the first-stage gas-liquid separator 19. Low-temperature nitrogen gas of 90 K or less is supplied to the second stage compressor 15. That is, nitrogen gas generated as a by-product of the generation of oxygen-enriched air in the first stage compressor 15, heat exchanger 16, expander 18, and gas-liquid separator 19 is supplied to the second stage compressor 15. Supplied.

  The nitrogen gas supplied to the second stage compressor 15 is isothermally compressed by the second stage compressor 15, cooled by the second stage heat exchanger 16, and adiabatic expansion by the second stage expander 18. And then cooled to a liquefaction temperature of nitrogen of 77K or less. Thereby, liquid nitrogen is produced. In the second-stage gas-liquid separator 19, the mixed fluid of nitrogen gas and liquid nitrogen supplied from the second-stage expander 18 is gas-liquid separated into nitrogen gas and liquid nitrogen.

  The discharge part 195 of the second-stage gas-liquid separator 19 is connected to the superconducting generator 25. Liquid nitrogen separated by the second-stage gas-liquid separator 19 and discharged from the discharge unit 195 is supplied to the superconducting generator 25 as a coolant for cooling the superconducting coil of the superconducting generator 25.

  The discharge cylinder 194 of the second-stage gas-liquid separator 19 is connected to the second-stage heat exchanger 16. The nitrogen gas separated by the second-stage gas-liquid separator 19 and discharged from the discharge cylinder 194 is supplied to the second-stage heat exchanger 16, and the second-stage heat exchanger 16 is supplied with the second-stage heat exchanger 16. This is used as a refrigerant for cooling the compressed nitrogen gas supplied from the compressor 15 by heat exchange. The liquid nitrogen after being used for cooling the superconducting coil by the superconducting generator 25 is also supplied to the second stage heat exchanger 16 as a refrigerant. Then, after being used for heat exchange in the second stage heat exchanger 16, the nitrogen gas discharged from the heat exchanger 16 is supplied to the tank cooling channel 54 to cool the LNG stored in the tank 50. To do.

  In the power plant according to the first example shown in FIG. 17, the parts denoted by the same reference numerals as the concentration system 10 of the above embodiment shown in FIG. 1 are configured in the same manner as the corresponding parts of the concentration system 10. .

  In the first embodiment, since the superconducting generator 25 that is small in size and can generate a large current is used, a compact and highly efficient power plant can be realized.

(Second embodiment)
Next, a propulsion system for a superconducting LNG tanker will be described as a second example to which the oxygen concentration system of the above embodiment is applied. The superconducting LNG tanker (hereinafter simply referred to as “tanker”) according to the second embodiment reforms the natural gas produced by gasification of LNG generated by the production of oxygen-enriched air in the oxygen enrichment system, thereby enriching the hydrogen. The fuel cell 34 generates power using the hydrogen-enriched gas and drives the superconducting motor 30 with the power generated by the fuel cell 34 to propel the ocean. FIG. 18 is a schematic system diagram of the tanker propulsion system according to the second embodiment.

  The tanker propulsion system according to the second embodiment includes a reformer 27, a superconducting motor 30, a propulsion screw 32, and a fuel cell 34.

  The reformer 27 is disposed downstream of the third heat exchanger 20 and generates a hydrogen-enriched gas having a hydrogen concentration increased by reforming natural gas discharged from the third heat exchanger 20.

  The superconducting motor 30 has a drive shaft connected to the propulsion screw 32 and operates when the electric power is supplied from the fuel cell 34 to rotate the propulsion screw 32. The superconducting motor 30 includes a superconducting coil formed by winding an oxide-based superconducting wire such as Bi-based or Y-based that undergoes a superconducting transition at the temperature of liquid nitrogen.

  The fuel cell 34 is supplied with hydrogen-enriched gas produced by the reformer 27 and oxygen-enriched air discharged from the third heat exchanger 20. The fuel cell 34 generates electric power by reacting hydrogen in the hydrogen-enriched gas with oxygen in the oxygen-enriched air. The fuel cell 34 is electrically connected to the superconducting motor 30 and the drive circuit 22, and the electric power generated by the fuel cell 34 is supplied to the superconducting motor 30 and the drive circuit 22. In the fuel cell 34, heat is generated with the generation of electric power, and the generated heat (waste heat) is supplied to the third heat exchanger 20 and the reformer 27.

  In the tanker propulsion system according to the second embodiment, the compressor 15, the first heat exchanger 16, the expander 18, the electric motor 17, and the gas-liquid separation device of the oxygen concentrating system as in the power plant according to the first embodiment. Two stages of 19 configurations are provided. The specific contents of this configuration are the same as in the case of the power plant of the first embodiment.

  The discharge unit 195 of the second-stage gas-liquid separator 19 is connected to the superconducting motor 30. The liquid nitrogen separated by the second-stage gas-liquid separation device 19 and discharged from the discharge unit 195 is supplied to the superconducting motor 30 as a coolant for cooling the superconducting coil of the superconducting motor 30. ing.

  Of the tanker propulsion system according to the second example shown in FIG. 18, the parts denoted by the same reference numerals as those of the concentration system 10 of the embodiment shown in FIG. 1 and the power plant of the first example shown in FIG. The concentrating system 10 and the corresponding parts of the power plant are configured similarly.

  In the second embodiment, since the superconducting motor 30 that is small and can generate a large torque is used, a compact and highly efficient tanker propulsion system can be realized.

  In general, in order to industrially use superconductivity, an extremely low temperature environment, specifically, an environment with a liquid nitrogen temperature of 77 K (−196 ° C.) or less is required. When a refrigerator is used to create such a temperature environment, the refrigerator is in an inefficient operation state where the theoretical maximum is Carnot efficiency of 34%, and in fact, less than half that. For this reason, it is difficult to make industrial use of superconductivity widely, and the use of superconductivity is limited to special applications such as an MRI inspection apparatus.

  On the other hand, as in the first and second embodiments, in various facilities and devices that use LNG as fuel, the cold heat of LNG as the fuel is diverted to the cryogenic temperature of the superconducting coil. Therefore, efficient superconducting industrial use is possible.

  Note that the oxygen concentrating system of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  In the concentration system 10 of the above embodiment, the electric power necessary for driving the electric motor 17 is obtained from the generator 21, but the present invention is not limited to this structure, and an electric power from the outside may be used. In this case, the generator 21 may not be provided.

  Moreover, the specific structure of a gas-liquid separator is not limited. The gas-liquid separation device 19 of the above embodiment is a so-called cyclone type gas-liquid separation device, but any device capable of gas-liquid separation under an extremely low temperature atmosphere (at an oxygen boiling point (90K) or lower atmosphere). The method of gas-liquid separation is not limited, and for example, a gas-liquid separator of a different type from the cyclone type such as a centrifugal fractionator may be used.

  Moreover, although the dehumidification guide part 13 is provided in the concentration system 10 of the said embodiment, this dehumidification guide part 13 is omissible. In this case, for example, a fourth heat exchanger for exchanging heat between the air supplied to the first heat exchanger 14 and nitrogen or nitrogen-rich air exhausted from the gas-liquid separator 19 may be provided. Good. That is, the dehumidification and pre-cooling (pre-cooling) of the air supplied to the first heat exchanger 14 is performed at a very low temperature (higher than the boiling point of nitrogen and lower than the boiling point of oxygen) exhausted from the gas-liquid separator 19 or You may carry out using the cold of nitrogen-rich air.

  Further, in the concentration system 10 of the above embodiment, the tank cooling channel 54 is provided, but this tank cooling channel 54 can be omitted.

  In addition, the third heat exchanger 20 of the above embodiment uses oxygen-enriched air discharged from the gas-liquid separator 19, LNG discharged from the second heat exchanger 16, and exhaust gas from the facility 55. Although it is the structure which carries out heat exchange, you may be comprised so that either one of the said oxygen-enriched air and the said LNG, and the waste gas from the facility 55 may be heat-exchanged.

  Moreover, in the concentration system 10 of the said embodiment, although LNG after heat-exchange in the 1st heat exchanger 14 is supplied to the 2nd heat exchanger 16, for example, the 2nd heat exchanger 16 Alternatively, the LNG may be directly supplied from the tank 50.

  In the above embodiment, the compression female rotor 156 and the compression male rotor 157 have tooth shapes that contact each other when they rotate together, while the expansion female rotor 182 and the expansion male rotor 183 interact with each other when they rotate together. Although it was configured to have a tooth profile that avoids contact, it is not necessarily limited to this configuration. For example, the compression female rotor 156 and the compression male rotor 157 may also have tooth shapes that avoid mutual contact when they rotate together. That is, the compression female rotor 156 may have the same tooth shape and cross section as the expansion female rotor 182 described above, and the compression male rotor 157 may have the same tooth shape and cross section as the expansion male rotor 183 described above.

  In this case, it is possible to prevent generation of frictional resistance due to mutual contact between the compression female rotor 156 and the compression male rotor 157. As a result, energy loss due to frictional resistance due to mutual contact between the compressed female rotor 156 and the compressed male rotor 157 can be prevented, and the power consumption of the electric motor 17 can be further reduced.

  However, in this case, the rotational force cannot be transmitted from the teeth 157a of the compression male rotor 157 to the teeth 156a of the compression female rotor 156. In this case, a transmission mechanism such as a gear mechanism is provided for transmitting the rotational force of the rotating portion 17a of the electric motor 17 to the rotor shaft 158 on the female rotor side and rotating the rotor shaft 158 in synchronization with the rotor shaft 166 on the male rotor side. Just do it.

  Further, a tooth profile that avoids mutual contact during rotation of the compression female rotor 156 and the compression male rotor 157 and a tooth profile that avoids mutual contact during rotation of the expansion female rotor 182 and the expansion male rotor 183 are formed. However, the present invention is not necessarily limited to removing the portions of the teeth 157a and 183a of the male rotors 157 and 183 that may contact the teeth 156a and 182a of the corresponding female rotors 156 and 182. For example, the compression female rotor 156 and the compression male rotor 157 are removed by removing the portions of the teeth 156a and 182a of the female rotors 156 and 182 that may contact the teeth 157a and 183a of the corresponding male rotors 157 and 183. And a tooth profile that avoids mutual contact during rotation of the expansion female rotor 182 and the expansion male rotor 183 may be formed.

  In the above embodiment, the electric motor 17 is configured to rotationally drive the rotating body including the compression male rotor 157 and the expansion male rotor 183. However, the present invention is not necessarily limited to this configuration. That is, the electric motor 17 may be provided on the rotating body including the compression female rotor 156 and the expansion female rotor 182 so that the electric motor 17 rotates the rotation body including the compression female rotor 156 and the expansion female rotor 182.

  In the above embodiment, the electric motor 17 is provided in the casing 150, and the electric motor 17 rotates the rotor shaft 166 in the middle between the compression male rotor 157 and the expansion male rotor 183. It is not limited to. For example, as shown in FIG. 19, the electric motor 17 is arranged outside the casing 150, and a rotor shaft 169 (see FIG. 5) extending from the compression male rotor 157 to the opposite side of the expansion male rotor 183 extends to the outside of the casing 150. The motor 17 may be attached to a portion of the rotor shaft 169 that extends out of the casing 150. The electric motor 17 may rotate the rotor shaft 169 to rotate the rotating body including the compression male rotor 157, the expansion male rotor 183, and the rotor shafts 166, 167, and 169. Similarly, the rotor shaft 161, 163, or 167 may be extended outside the casing 150, and the electric motor 17 may rotate the extended rotor shaft outside the casing 150.

10 Oxygen concentrating system 13 Dehumidification guide (guide channel)
14 1st heat exchanger 141a 1st flow path (outer flow path)
141b Second channel (inner channel)
15 Compressor 156 Compressed female rotor 157 Compressed male rotor 16 Second heat exchanger 160 Heat insulation part 17 Electric motor 18 Expander 182 Expansion female rotor 183 Expansion male rotor 19 Gas-liquid separator 190 Separation cylinder 194 Discharge cylinder (exhaust part)
195 Discharge unit 20 Third heat exchanger 21 Generator 50 Tank 52 Insulating wall 54 Tank cooling channel 55 Facility

Claims (13)

An oxygen concentrating system for increasing the oxygen concentration of input air,
A first heat exchanger for exchanging heat with the liquefied natural gas from the air charged into the oxygen concentration system;
A compressor that compresses the air after heat exchange in the first heat exchanger to a predetermined pressure;
A second heat exchanger that exchanges heat between the air compressed by the compressor and liquefied natural gas;
An expander for adiabatically expanding the air heat-exchanged in the second heat exchanger;
A gas-liquid separation device that performs gas-liquid separation of air adiabatically expanded by the expander;
An electric motor that drives the compressor and the expander,
The compression ratio of the compressor and the expansion ratio of the expander are set so that the temperature of the air after the adiabatic expansion is higher than the boiling point of nitrogen and lower than the boiling point of oxygen, respectively.
The compressor is a screw type compressor having a compression female rotor that is a screw rotor and a compression male rotor that is a screw rotor meshing with the compression female rotor,
The expander is a screw type expander having an expansion female rotor that is a screw rotor and an expansion male rotor that is a screw rotor that meshes with the expansion female rotor,
The compression female rotor and the expansion female rotor are connected to each other so as to be integrally rotatable around the same axis,
The compression male rotor and the expansion male rotor are coupled to each other so as to be integrally rotatable about the same axis,
The electric motor includes at least one of the rotating female rotor including the compression female rotor and the expansion female rotor coupled thereto, and the other rotating body including the compression male rotor and the expansion male rotor coupled thereto. An oxygen concentration system that rotates a rotating body.   The oxygen concentrating system according to claim 1, wherein the expanded female rotor and the expanded male rotor each have a tooth profile such that mutual contact is avoided when the rotors rotate together.   The oxygen concentrating system according to claim 2, wherein the compression female rotor and the compression male rotor each have a tooth profile such that mutual contact is avoided when the rotors rotate together.   The second heat exchanger exchanges heat between liquefied natural gas after heat exchange in the first heat exchanger and air compressed by the compressor. The oxygen concentrating system according to any one of the above.   The said gas-liquid separator is provided with the separation cylinder extended up and down, and is a cyclone type gas-liquid separation apparatus which rotates the supplied air within the said separation cylinder. Oxygen enrichment system.   The first heat exchanger has a plurality of flow paths through which the liquefied natural gas or the air flows for heat exchange, and most of the plurality of flow paths are outside the first heat exchanger. The oxygen concentrating system according to any one of claims 1 to 5, wherein the air is configured to flow through an outer flow path that is a close flow path.   The said 1st heat exchanger has an adsorbent which is arrange | positioned in the space which is connected in the said outer flow path or the said outer flow path in the said 1st heat exchanger, and contains a zeolite. Oxygen enrichment system.   The second heat exchanger has a plurality of flow paths through which the liquefied natural gas or the air flows for heat exchange, and most of the plurality of flow paths is outside the second heat exchanger. The oxygen concentration system according to any one of claims 1 to 7, wherein the liquefied natural gas is configured to flow through an outer channel that is a near channel.   The oxygen concentration system according to claim 8, wherein the second heat exchanger includes a heat insulating portion that surrounds the entire plurality of flow paths from the outside.   The liquefied natural gas after the heat exchange in the first heat exchanger and the liquefied natural gas after the heat exchange in the second heat exchanger and the gas-liquid And a third heat exchanger for exchanging heat between the air containing the liquid separated in the separator and discharged from the gas-liquid separator, and the exhaust gas exhausted from the facility for burning the natural gas. Item 10. The oxygen concentration system according to any one of Items 1 to 9. Arranged in a flow path through which air after heat exchange in the third heat exchanger flows or a flow path through which natural gas, which is liquefied natural gas vaporized by heat exchange in the third heat exchanger, flows. Further equipped with a generator,
The oxygen concentration according to claim 10, wherein the generator generates power using a flow or pressure of air or natural gas flowing through a flow path in which the generator is disposed, and supplies the generated power to the motor. system. A tank cooling flow path provided between a tank in which liquefied natural gas is stored and a heat insulating portion surrounding the outside of the tank;
The gas-liquid separator has an exhaust part for discharging separated gas, and the exhaust part is connected to the tank cooling channel so that the exhausted gas flows to the tank cooling channel. The oxygen concentration system according to any one of 1 to 11. A guide channel for guiding the air introduced into the oxygen concentration system to the first heat exchanger;
The said guide flow path is arrange | positioned along the said tank so that the air which flows through the inside can exchange heat with the liquefied natural gas in the said tank. The oxygen enrichment system described.

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