KR101669729B1 - Air liquefaction system using lng cold energy with ejector expansion device entraining expanded vapor - Google Patents

Air liquefaction system using lng cold energy with ejector expansion device entraining expanded vapor Download PDF

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KR101669729B1
KR101669729B1 KR1020140157893A KR20140157893A KR101669729B1 KR 101669729 B1 KR101669729 B1 KR 101669729B1 KR 1020140157893 A KR1020140157893 A KR 1020140157893A KR 20140157893 A KR20140157893 A KR 20140157893A KR 101669729 B1 KR101669729 B1 KR 101669729B1
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air
liquid
ejector
expansion device
compressor
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KR1020140157893A
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Korean (ko)
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KR20160057108A (en
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강희자
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강희자
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0012—Primary atmospheric gases, e.g. air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0221—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using the cold stored in an external cryogenic component in an open refrigeration loop
    • F25J1/0224—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using the cold stored in an external cryogenic component in an open refrigeration loop in combination with an internal quasi-closed refrigeration loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/62—Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/04—Compressor cooling arrangement, e.g. inter- or after-stage cooling or condensate removal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression of the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/60—Expansion by ejector or injector, e.g. "Gasstrahlpumpe", "venturi mixing", "jet pumps"
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/90—Processes or apparatus involving steps for recycling of process streams the recycled stream being boil-off gas from storage

Abstract

In the present invention, liquefied air is obtained by liquefying the raw material air introduced from the atmosphere by using the cold heat of the LNG and the expansion air sucking type ejector expander, thereby eliminating the need for separation of oxygen and nitrogen, And more particularly, to a liquid air producing apparatus which is significantly reduced. The apparatus configuration of the present invention includes: a compressor for compressing air; An LNG cold heat exchanger in which air passing through the compressor is cooled by LNG cold heat; a first ejector expansion device for expanding air passing through the LNG cold / hot heat exchanger to an intermediate pressure; A liquid ejector in which air passing through the first ejector expansion device is separated into a gas and liquid air; Gas air of intermediate pressure in the separated gas and liquid is returned back to the compressor after heat exchange in the air sucked into the first ejector expansion device and the exhaust air heat exchanger and compressed; A second ejector expansion device in which the liquid air is further inflated to a final pressure; A liquid air storage tank in which liquid air produced through the second ejector expansion device is finally stored; and cold gas air in the storage tank is sucked into the first ejector expansion device.

Description

TECHNICAL FIELD [0001] The present invention relates to an air liquefaction system,

The present invention relates to a system for obtaining liquid air by reducing the temperature of air by using LNG cold heat, and more particularly, to a system for increasing the amount of liquid air produced by applying an ejector expansion device and reducing power required by using LNG cold heat To an air liquefaction system.

The present invention particularly liquefies the raw material air introduced from the atmosphere by using the cold heat of liquefied natural gas (hereinafter referred to as LNG) using an ejector expander, thereby obtaining more liquid air and eliminating the separation of oxygen and nitrogen, The present invention relates to a device and a method of operating the device in which the conventional liquefaction facility is greatly reduced.

BACKGROUND ART Conventionally, an air-liquid separator for electric use is an apparatus for separating nitrogen and oxygen in air and liquefying them, and is composed of a high-pressure compression, cooling, expansion, and liquefaction rectification tower cycle of 100 to 125 bar. The LNG air-cooled liquefied air separation unit also produces liquid oxygen and liquid nitrogen. However, by using LNG cold, the pressure of the compressor is reduced to 60 bar (6 MPa). Use amount of the phase change can be used as cold heat that vaporizes to a gaseous state is NG (natural gas) from the liquid LNG (liquefied natural gas) is the case of the LNG pressure 72kg / cm 2 in -150 ~ -155 ℃ to 0 ℃ About 160 kcal / kg, and the lowering temperature of air by heat exchange with LNG is -130 to 140 ° C. The electric or LNG cold air separation and liquefaction separation system for producing liquid oxygen and liquid nitrogen by separating these air is disadvantageous in that it is complicated and expensive.

The present invention relates to a system for directly liquefying air without separating air into oxygen and nitrogen. Conventional related processes include a precooled Linde-Hampson system (FIG. 1) and an LNG cold- Is applied to the air liquefaction process. The processes of Figs. 1 and 3 do not have a liquefying rectifier for separating liquid nitrogen and liquid oxygen, but instead require a pre-cooling process for lowering the temperature of the air using a freezer.

The outline of the air liquefying apparatus of Fig. 1 according to the conventional example will be briefly described. The air as the raw material gas is compressed to 50-200 bar higher than the critical pressure in the compressor 100, and then the pre-cooling process 110 by the refrigerators 150-140-120-110 and the pre- The temperature is lowered to -140 ° C. by the heat exchange with the cold air 110 and the isenthalpic expansion process is caused by the expansion valve 120 so that the pressure drops to 1 atmospheric pressure at 200 bar pressure and 10% The required energy amount is 4,56 kJ / kg, which is 4,560 kJ / s (4,560 kW) for a flow of 1 kg / s of air, and much more power is required than the present invention. The disadvantage of this precooled Linde-Hanson system is the high pressure process, which requires a relatively high pressure and relatively low yield of liquid air by applying an expansion valve to the large power requirement and expansion device. FIG. 2 shows the theoretical liquid yield according to each pressure according to the refrigerant flow rate of the precooling refrigerator in this precooled Linde-Hamson air liquefaction system. It is understood that compression of 100 bar or more is required to obtain an appropriate liquid.

3 is a Japanese Patent Application No. 52154750 (Dec. 22, 1977), which discloses an LNG cooler utilizing turbine liquefied air liquefaction process in which a compressor 100 and an expansion turbine 160 are connected to one shaft, The entropy expansion occurs, and the use of the expansion work as the auxiliary power source of the compressor 100 reduces the power required by the compressor and acquires liquid air at a constant speed at all times. In addition, instead of the refrigerator, the LNG cold heat 110 is used in the same manner as in the present invention. In the outline of this process, the raw air passed through the filter 170 passes through the compressor 100, is cooled, and water, CO 2 And is expanded to a final pressure of atmospheric pressure by the thermal expansion of the turbine 160 after the heat exchange with the LNG in the heat exchanger 110 and is collected in the storage tank 130 via the refiner 180. At this time, the temperature of the air flowing into the turbine 160 is -140 ° C, which is higher than the LNG temperature of -155 ° C, in the LNG heat exchanger 110, and the temperature of the air after isentropic expansion is -193.8 ° C.

In this process, since the turbine 160 is applied to a cryogenic condition of -130 to -140 ° C, there is a problem of durability and high price, and the system pressure is higher than that of the process of the present invention, resulting in a large power consumption. The isentropic expansion device of the same isotropic expansion type as the turbine expansion type has the ejector expansion device applied in the present invention. Advantages of the ejector system include that the high-pressure air expands with the pressure drop and sucks the outside air It is. In addition, the isentropic heat expansion occurs in the expansion process, and the amount of liquid air is increased. Unlike a turbine, it has a simple structure and excellent durability and easy maintenance because there is no driving part.

On the other hand, there is no domestic technology for producing liquid air by liquefying air itself without separating the air into liquid oxygen and liquid nitrogen using LNG cold heat.

In the conventional air liquefying apparatus process using a turbine-compressor integrated LNG cold heat, there is the following problem.

(1) Since the incoming air flows into the turbine 160, which is an expansion device after the LNG heat exchange 110, the pre-cooling temperature is only -140 ° C., and the pressure must be 60 bar or more to obtain the liquid.

(2) By connecting the compressor and the turbine to one shaft, the structure is complicated mechanically, and the ultra-low temperature turbine of -150 ° C takes a large production cost, and it has difficulties in failure and maintenance, Can not be avoided.

(3) Due to the complex structure of the turbine and the compressor connected to the compressor, it is difficult to operate the turbine. When the amount of air expansion of the turbine is reduced, the number of rotations of the turbine decreases and the reduction of the compression work of the compressor is greatly reduced. The descending ability is deteriorated and the yield of the liquid air is greatly reduced.

It is therefore an object of the present invention to provide a turbine integrated compressor which eliminates the mechanical complexity of the turbine integrated compressor to prevent malfunctions, thereby greatly improving the annual operating rate and applying the ejector, which is the same isentropic expansion device as the turbine without a drive, And is capable of sufficiently effectively utilizing the cold and cold of the LNG.

According to an aspect of the present invention, there is provided a compressor comprising: a compressor for compressing air; A heat exchanger in which air passing through the compressor is cooled by LNG cold heat; a first ejector expansion device for expanding air passing through the heat exchanger to an intermediate pressure; A liquid ejector in which air passing through the first ejector expansion device is separated into a gas and liquid air; The gas air in the separated gas and liquid further reduces the temperature of the air sucked into the first ejector expansion device and is compressed back to the compressor; A second ejector expansion device in which the liquid air is further inflated to a final pressure; A storage tank in which liquid air and gas air produced after expansion are ultimately stored, and cold expanded air that is vaporized in the tank is provided to the first ejector expansion device.

In addition, the expansion device may be composed of a single or a plurality of expansion devices, that is, first, second, and third expansion devices.

According to the embodiments of the present invention, the amount of liquid air produced by applying the ejector in which isentropic thermal expansion occurs in the expansion device is increased. Further, since the ejector has a function of sucking the fluid at the time of expansion, the amount of compressed air is reduced by constituting the step of sucking the air gas of the low pressure stage generated after the expansion. Further, after the air is expanded to the intermediate pressure by the first ejector expansion device, the medium pressure gas collected in the liquid separator is sucked into the compressor after the heat exchange, so that the pressure is 12 bar (1.2 MPa) Effect.

According to the present invention, by applying the expanded air suction type ejector, the pressure of the raw material air is lowered compared to the conventional process, and the required power is reduced accordingly. In order to liquefy the air, precooling by a refrigerator is indispensable. In the present invention, a refrigerator is not required by applying LNG cold heat.

Another effect of the present invention is that the conventional process equipment, such as the cryogenic turbine and the air separation rectifier, is removed, so that the process is simple, the maintenance is easy, and the operation rate is increased.

1 is a schematic view of a conventional precooled Linde-Hampson air liquefaction process.
2 is a graph showing the liquid yield according to the pressure of the precooled Linde-Hamson process.
3 is a schematic view of an LNG-cooled turbine-applied air liquefaction process.
4 is a view showing a system of an apparatus for manufacturing an LNG cooler-use inflator type inhaled ejector-applied liquid air according to an embodiment of the present invention.

Means for Solving the Problems The present invention has been made in order to solve the problems described above, and the means employed in the liquid air production apparatus according to claim 1 is a compressor comprising a compressor for introducing raw material air from an atmospheric air and compressing the air to a predetermined pressure, A cooling air of a cryogenic LNG having a temperature of -155 DEG C, cooled by an additional discharge air heat exchanger to generate a liquid while pressure is lowered in the ejector expansion device, And a process of entropy expansion.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The liquid air production apparatus of FIG. 4 according to the present invention shows a two-stage expansion process, which can be constituted by a single stage or a multi-stage of two or more stages, and consists largely of a compression process, a cooling process, and an expansion process.

4, the raw material air sucked from the atmosphere through the filter is compressed to a pressure of 30 to 40 bar, which is about 60% of the conventional process, for example, at a predetermined pressure in the compressor 200. Compression is formed by two stages of adiabatic compression. The atmospheric air is compressed to 11.5 bar and 90 ° C. in the first stage compressor 200 and then to -20 ° C. in the LNG cooling and cooling system 220 and compressed to 40 bar and 90 ° C. in the second stage compressor 210 Is also cooled in the LNG cooler / cooler 230. The raw material air discharged from the compressor 210 is cooled to -140 DEG C in the LNG cold heat exchanger 240 through the flow path a. In this case, since the air treatment units such as the adsorbent for removing moisture and carbon dioxide gas are all the same, they are omitted.

The cooled air is cooled to an additional-155 ° C in the exhaust air heat exchanger 250 and then injected into the first ejector expansion device 260. In the first ejector expansion device, cold air at -155 DEG C is rapidly expanded from the throat portion of the first ejector expansion device 260 to an intermediate pressure of 12 bar (1.2 MPa) to be a mixed air of liquid and gas . At this time, the expansion of the first ejector expansion device 260 is an isentropic adiabatic expansion process, which results in an increase in the amount of the air liquid generated compared with the conventional isenthalpic expansion process. Also, during the expansion, the temperature of -193.8 캜 cold air of the storage tank 290 is sucked to lower the temperature after expansion. The air that has passed through the first ejector expansion device 260 is separated into gas and liquid in the liquid-liquid separator 270, and the gas in the separated gas and liquid flows back along the pipe line d of the discharge air heat exchanger 250 And is sucked into the compressor (200).

The liquid in the liquid-liquid separator 270 is expanded to the final atmospheric pressure of 1.013 bar in the second ejector expansion device 280 and is collected in the finally insulated storage tank 290. The vaporized gas in the tank flows along the flow path e 1 ejector expansion device 260 as shown in FIG.

The 12 bar cold air of the liquid-liquid separator 270 conveyed to the compressor 200 is mixed with the intake air at a pressure of 1.013 bar at an atmospheric pressure of 1.013 bar to raise the pressure to 3.65 bar and the temperature falls to -11.2 ° C at 35 ° C. So that compression energy and cooling energy can be reduced.

For the analysis according to the present invention, the amount of air introduced from the atmosphere is interpreted on the basis of 1 kg / s. The thermodynamic properties used in the analysis were Refprop 9.1 program developed by National Institute of Standards and Technology (NIST)

1) Energy required for compression process

0.63 kg / s of air at 35 ° C. and 1.013 bar atmospheric condition were introduced and mixed with the conveying air of the liquid separator 270 at -163.6 ° C., 12 bar, and 0.24 kg / Is introduced into the compressor (200). At this time, compression is formed by two-stage adiabatic compression. The atmospheric air is compressed to 11.5 bar and 90 ° C. in the first stage compressor 200 and then cooled down to -20 ° C. by the cold heat of the LNG cooler and cooler 220 and compressed to 40 bar and 90 ° C. in the second stage compressor 210 And cooled by the cold heat of the LNG cooler / cooler 230. In this case, the power required for the first stage compressor and the power required for the second stage compressor are 101.21 + 109.65 = 210.86 kJ / s (210 kW).

2) Cooling process (using LNG cold heat and recovered cold air)

The air at a pressure of 40 bar is cooled in the LNG cold heat exchanger 240 by LNG at -150 to -155 deg. The enthalpy difference, which is the energy required to cool the air, is 343 kJ / s. The amount of LNG required to cool the LNG is 160 kcal / kg (670 kJ / kg) per 1 kg of LNG, so an LNG amount of 0.52 kg / s is required. The cooled air at -140 DEG C is further reduced to -146.8 DEG C at a flow rate of 0.24 kg / s, which is air recovered from the liquid separator 270 to the compressor 200, at a temperature of -163.6 DEG C and 12 bar. At this time, the liquid LNG at -155 ° C provides a low temperature in the LNG cold heat exchanger 250, and is returned to the natural gas (NG) state by itself.

3) Ejector expansion process

In the first ejector expansion device 260, the temperature is -161.0 DEG C, and the liquid 76.0% gas 24.0% is produced while the pressure of the air of 40 bar and -146.8 DEG C is lowered to 12 bar with equal entropy. At this time, the temperature of the air discharged from the ejector is -163.6 ° C due to the suction of the cold air (-193.8 ° C) of the storage tank 290. The gas air (-163.6 ° C, 0.24 kg / s) of the liquid-liquid separator 270 passes through the exhaust air heat exchanger 250 and the air temperature of -140 ° C. passing through the LNG cold heat exchanger 240 is further increased to 6.8 ° C. Which is lowered to -146.8 캜, and flows into the compressor 200 at -150 캜.
At this time, the available enthalpy amount from the air of 0.24 kg / s delivered from the liquid-liquid separator 270 in the discharge air heat exchanger 250 is: Q = mx dh = (0.24) (111.7 - (- 26.7)) = 36 kJ / s.

0.76 kg / s of the saturated liquid of the liquid-liquid separator 270 drops to -193.8 ° C with the temperature dropping to the atmospheric pressure of 1.013 bar at the second ejector expansion device 280, and 68.3% of liquid and 31.7% of gas are obtained. Of these, the saturated liquid 0.519 kg / s (0.76 kg / s x 0.683) is collected in the storage tank 290 at the yield of liquid production. The low-pressure cold air in the storage tank is sucked into the first ejector expansion device 260 at 31.7% (0.241 kg / s = 0.76 kg / s x 0.317).

That is, in the compressor, 0.519 kg / s of liquid air was obtained with respect to 1 kg / s of compressed air, and the yield was 51.9%. At this time, the generated gas is sucked into the first ejector expansion device 260 and sucked into the compressor 200 again.

 As can be seen from the above analysis, in the conventional air liquefaction separation system, the power demand is increased due to the generation of low liquid or high pressure due to high pressure, isenthalpy expansion or turbulent entropy heat expansion. On the other hand, the liquid air production apparatus employing the LNG cold heat using ejector according to the present invention increases the liquid air yield to 51.9% by effectively using the LNG cold heat due to expansion of the isentropic expansion process, have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, The present invention can be variously modified and changed. That is, a plurality of compressors including a single stage can be used for compression through a compressor, a plurality of compressors can be applied according to the capacity of the heat exchanger, and a plurality of expansion processes of one or more ejector expansions can be applied. And are also included within the scope of the present invention.

100, 210, 220: compressors 110, 220, 230: LNG cooler /
120: expansion valve 130, 290: liquid air storage tank
140: condenser of refrigerating device 150: compressor of refrigerating device
160: expansion turbine 170: air filter
180: air purifier 240: LNG cold heat exchanger
250: exhaust air heat exchanger 260: first ejector expansion device
270: Liquid separator 280: Second ejector expansion device

Claims (2)

A compressor for compressing the raw air;
An LNG cold / hot heat exchanger for cooling the air passing through the compressor using LNG cold heat;
An exhaust air heat exchanger for further cooling the air passing through the LNG cold / hot heat exchanger using air recovered by a compressor;
A first ejector expansion device for expanding the cold air to a first intermediate pressure;
A liquid separator for separating the air passing through the first ejector expansion device into a gas and a liquid;
A second ejector expansion device and a liquid air storage tank for further expanding the liquid separated at the liquid separator to atmospheric pressure;
Wherein the cold air in the storage tank has a flow path that is sucked into the first ejector expansion device; And
Wherein the cold air of the liquid separator further cools the air in the exhaust air heat exchanger and flows into the compressor. The method according to claim 1,
Wherein the compressed air is sucked by sucking gas air at atmospheric pressure of the storage tank during isentropic thermal expansion of the ejector which is an expansion device.
KR1020140157893A 2014-11-13 2014-11-13 Air liquefaction system using lng cold energy with ejector expansion device entraining expanded vapor KR101669729B1 (en)

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