LNG (Liquefied Natural Gas) cold energy air liquefaction system based on vapor compression type heat pump circulation

Abstract

The utility model relates to the technical field of air liquefaction, in particular to an LNG (Liquefied Natural Gas) cold energy air liquefaction system based on vapor compression type heat pump circulation, which comprises an LNG gasification circulation unit and a vapor compression type cold energy transmission heat pump circulation unit in which a circulation refrigerant circulates, and is used for recovering LNG liquid low-temperature cold energy to liquefy lower-temperature air; an air pressurization liquefaction circulation unit; and the secondary refrigerant gas cooling circulation unit is used for recovering sensible heat cold energy of gasified LNG and cooling gas compressed by the steam compression type cold energy transmission heat pump circulation unit and the air pressurization liquefaction circulation unit. According to the LNG cold energy air liquefaction system based on the steam compression type heat pump cycle, LNG liquid low-temperature cold energy is recycled, the temperature grade of the cold energy is improved, then lower-temperature air is liquefied, phase change throttling heat exchange is adopted in the steam compression cycle, cooling is fast, the variable load capacity is high, and the energy consumption is low. And the LNG cold energy is efficiently recycled to continuously liquefy air under the LNG discontinuous supply fluctuation working condition.

Description

TECHNICAL FIELD

[0001] The utility model relates to air liquefaction technical field especially relates to a LNG cold energy air liquefaction system based on vapor compression type heat pump circulation. BACKGROUND

[0002] LNG is super low temperature liquid natural gas, needs to maintain extremely low temperature (about -162 DEG C) during storage and transportation. LNG releases a large amount of high-grade cold energy in the regasification process before supplying users in this low temperature state. Through years of practice, LNG cold energy utilization includes cold energy power generation, air separation, light hydrocarbon recovery, low temperature crushing, seawater desalination, frozen refrigeration, dry ice manufacturing and the like, and the existing LNG cold energy utilization technology cannot efficiently utilize the cold energy of LNG in the whole temperature zone when used alone, and the cold energy loss is large. With the rapid growth of LNG consumption and the intensification of global energy supply situation, efficient utilization of LNG cold energy is particularly important.

[0003] Air liquefaction is a process of converting air from gaseous state to liquid state by reducing the temperature of air below its liquefaction point, which is widely used in industrial gas production, medical care, food processing, oxygen-enriched combustion and carbon capture, energy storage and hydrogen liquefaction precooling and other fields.

[0004] In the prior art, air liquefaction is carried out by using LNG gasification, including an air expansion refrigeration system using direct heat exchange between LNG and air, but there is a safety risk of flammable and explosive hydrocarbon substances in air contact. In the air liquefaction system using pressurized nitrogen as an intermediate transmission medium for LNG cold energy, according to the properties of methane, LNG is gasified at normal pressure, and its boiling point is -162 DEG C. The pressure of nitrogen corresponding to this temperature is 1.6 MPa, that is, only when the pressure of nitrogen is above 1.6 MPa can LNG cold energy be directly utilized. The high circulating pressure of nitrogen results in high energy consumption. In order to reduce the energy consumption of the system using nitrogen circulation, a low-temperature nitrogen compressor with high price is usually used, which results in poor economy and poor reliability of the low-temperature compressor. At the same time, the existence of complex heavy hydrocarbon components in LNG causes the phase change temperature of LNG to change with the gasification process, and the gasification amount of LNG fluctuates greatly and is discontinuous with the change of gas consumption of users. Therefore, the existing LNG cold energy air liquefaction system has problems such as high operating pressure, slow cooling speed, low efficiency, poor economy of using expensive low-temperature compressors, inability to adapt to discontinuous gasification of LNG, and weak air liquefaction variable load regulation capacity.

[0005] Therefore, how to provide a cold energy recovery air liquefaction cycle more suitable for LNG components and discontinuous gasification is a technical problem that those skilled in the art need to solve. UTILITY MODEL CONTENTS

[0006] The utility model provides a kind of LNG cold energy air liquefaction system based on vapor compression heat pump cycle, to solve the defect that LNG condensing air liquefaction system in prior art cannot adapt to LNG discontinuous supply, realize the recovery of LNG liquid cryogenic cold energy and promote cold energy temperature grade to further liquefy lower temperature air, vapor compression cycle uses throttling phase change heat exchange, cooling is fast, variable load capacity is strong, adapt to LNG discontinuous supply fluctuation operating condition under high-efficiency recovery LNG cold energy to air continuous liquefaction.

[0007] The utility model provides a kind of LNG cold energy air liquefaction system based on vapor compression heat pump cycle, it includes:

[0008] LNG gasification circulation unit, including first heat exchanger, second heat exchanger and LNG pressure regulating device;The first heat exchanger is connected with LNG storage tank;The LNG pressure regulating device is used to promote the pressure of LNG;

[0009] Vapor compression cold energy transmission heat pump circulation unit, inside circulating refrigerant flows, for the recovery of LNG liquid cryogenic cold energy to liquefy lower temperature air;

[0010] Air pressurization liquefaction circulation unit, including air compressor, air cooler and third heat exchanger connected in turn;And the third heat exchanger supplies air and circulating refrigerant heat exchange;

[0011] Coolant gas cooling circulation unit is used for the recovery of sensible heat cold energy of LNG after gasification, and the vapor compression cold energy transmission heat pump circulation unit and the air pressurization liquefaction circulation unit compressed gas cooling.

[0012] According to the utility model provides a kind of LNG cold energy air liquefaction system based on vapor compression heat pump cycle, the vapor compression cold energy transmission heat pump circulation unit is superposed, including methane heat pump circulation loop and argon heat pump circulation loop, circulating refrigerant that flows respectively is methane and argon;

[0013] The methane heat pump circulation loop includes the circuit formed by first compressor, first gas cooler, the first heat exchanger, first gas throttling device and fourth heat exchanger;Methane passes through the first gas cooler and the coolant gas cooling circulation unit cooling;

[0014] The argon heat pump circulation loop includes the circuit formed by second compressor, second gas cooler, the fourth heat exchanger, second gas throttling device and the third heat exchanger;Argon passes through the second gas cooler and the coolant gas cooling circulation unit cooling.

[0015] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device, a cryogenic pump and an ejector, the LNG throttling device and the cryogenic plate are connected in parallel and are both arranged at the upstream of the first heat exchanger, and the ejector is arranged at the downstream of the second heat exchanger.

[0016] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0017] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0018] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0019] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0020] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0021] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0022] The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle, the LNG pressure regulating device comprises a LNG throttling device and a natural gas compressor, the LNG throttling device is arranged at the upstream of the first heat exchanger, and the natural gas compressor is arranged at the downstream of the second heat exchanger.

[0023] The LNG cold energy air liquefaction system based on the vapor compression type heat pump cycle provided by the utility model recovers LNG liquid low-temperature cold energy to liquefy lower-temperature air through the vapor compression type cold energy transmission heat pump cycle unit; recovers the sensible heat cold energy of the gasified LNG through the cold carrier gas cooling cycle unit to cool the gas compressed by the vapor compression type cold energy transmission heat pump cycle unit and the air pressurization liquefaction cycle unit; the utility model uses the heat pump technology to pump the liquefaction condensation heat of the lower-temperature air to the LNG gasification temperature zone with higher temperature through the vapor compression type circulation, that is, to recover the LNG liquid low-temperature cold energy and improve the cold energy temperature grade to liquefy the lower-temperature air; the vapor compression circulation adopts throttling phase change heat exchange, has fast cooling and strong variable load capacity, and is suitable for efficient recovery of the LNG cold energy to continuously liquefy the air under the discontinuous supply fluctuation condition of the LNG.

[0024] The vapor compression type cold energy transmission heat pump cycle unit can effectively match the change of the phase change temperature of the LNG in the gasification process caused by the complex heavy hydrocarbon components of the LNG by adopting methane and argon as the two-stage cascade heat pump cycle refrigerants.

[0025] The latent heat of the argon is higher than that of the nitrogen, the argon circulation has less gas volume and low energy consumption, the normal-temperature compressor is used in each circulation unit of the system, the energy saving effect is better than that of the nitrogen circulation in the existing LNG cold energy air liquefaction system using the low-temperature compressor, the air liquefaction system is energy-saving, and the economy and reliability of the system are improved.

[0026] The critical temperature and the boiling point of the argon are higher than those of the nitrogen under the same pressure, and the argon is between the nitrogen and the methane, so that the argon is used as the circulation medium, the system pressure is reduced, the requirement for the pressure resistance of the equipment is reduced, and the energy saving can be effectively realized.

[0027] The heat exchange between the cold carrier and the gasified LNG is used for gas cooling in each circulation unit of the system, the further use of the sensible heat of the LNG is realized, the compressor energy consumption in the system is reduced, the efficient use of the cold energy in the whole temperature range of the LNG latent heat and sensible heat in the single air liquefaction separation technical application scene is realized, and the energy saving benefit is huge compared with the conventional pure electric refrigeration liquid air production system and the existing LNG cold energy air liquefaction system. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0029] Figure 1 is one of the structural principle diagrams of the LNG cold energy air liquefaction system based on the vapor compression heat pump cycle provided by the present application.

[0030] Figure 2 is the second structural principle diagram of the LNG cold energy air liquefaction system based on the vapor compression heat pump cycle provided by the present application.

[0031] Figure 3 is the third structural principle diagram of the LNG cold energy air liquefaction system based on the vapor compression heat pump cycle provided by the present application.

[0032] Figure 4 is the fourth structural principle diagram of the LNG cold energy air liquefaction system based on the vapor compression heat pump cycle provided by the present application.

[0033] Figure 5 is the fifth structural principle diagram of the LNG cold energy air liquefaction system based on the vapor compression heat pump cycle provided by the present application.

[0034] Reference signs:

[0035] 1, LNG gasification circulation unit; 2, vapor compression cold energy transmission heat pump circulation unit; 3, air pressurization liquefaction circulation unit; 4, refrigerant gas cooling circulation unit; 11, first heat exchanger; 12, second heat exchanger; 13, LNG throttling device; 14, natural gas compressor; 15, low temperature pump; 16, ejector; 17, natural gas cooling device; 21, methane heat pump circulation loop; 22, argon heat pump circulation loop; 211, first compressor; 212, first gas cooler; 213, first gas throttling device; 214, fourth heat exchanger; 221, second compressor; 222, second gas cooler; 223, second gas throttling device; 31, air compressor; 32, air cooler; 33, third heat exchanger; 34, air drying purifier; 41, refrigerant circulating pump; 42, refrigerant shunt; 43, refrigerant combiner. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the utility model clearer, the technical scheme of the utility model will be described clearly and completely in combination with the drawings in the utility model below. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skilled in the art without creative labor belong to the protection scope of the utility model.

[0037] In the description of the embodiments of the utility model, it should be explained that the orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is the orientation or position relationship shown based on the drawings, and is only for the convenience of describing the embodiments of the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0038] The embodiments of the utility model will be described below in combination with Figures 1-5 The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle of the utility model is described.

[0039] Figure 1 The LNG cold energy air liquefaction system based on the vapor compression heat pump cycle of the utility model is described. Figure 1 As shown in the figure, it comprises an LNG gasification circulation unit 1, a vapor compression cold energy transmission heat pump circulation unit 2, an air pressurization liquefaction circulation unit 3 and a cold carrier gas cooling circulation unit 4.

[0040] The LNG gasification circulation unit 1 comprises a first heat exchanger 11, a second heat exchanger 12, an LNG pressure regulating device and corresponding pipelines. The first heat exchanger 11 is connected with an LNG storage tank; the LNG pressure regulating device is used to increase the pressure of LNG, and the LNG is gasified from the LNG storage tank and increased to a city gas pipeline network.

[0041] The vapor compression cold energy transmission heat pump circulation unit 2 circulates with a circulating refrigerant, which is used to recover the low-temperature cold energy of LNG liquid to liquefy air at a lower temperature.

[0042] The air pressurization liquefaction circulation unit 3 comprises a series circuit composed of an air compressor 31, an air cooler 32 and a third heat exchanger 33 connected in sequence; and the third heat exchanger 33 exchanges heat between air and the circulating refrigerant.

[0043] The refrigerant gas cooling circulation unit 4 is used for recovering the sensible heat of the gasified LNG and cooling the compressed gas of the vapor compression type cold energy transmission heat pump circulation unit 2 and the air pressurized liquefaction circulation unit 3.

[0044] The LNG cold energy air liquefaction system based on the vapor compression type heat pump circulation provided by the embodiment of the utility model can pump the air liquefaction condensation heat with a lower liquefaction temperature to a LNG vaporization temperature zone with a higher temperature through the vapor compression type heat pump circulation, that is, the LNG liquid low-temperature cold energy is recovered and the cold energy temperature grade is improved through the vapor compression type heat pump circulation to liquefy air with a lower temperature, and meanwhile, the vapor compression type heat pump can adjust the circulation quality of the refrigerant in a wide range, so that the LNG cold energy can be efficiently utilized and the air can be stably liquefied under the fluctuating working conditions of discontinuous LNG vaporization.

[0045] In an embodiment of the utility model, the vapor compression type cold energy transmission heat pump circulation unit 2 can be a single-stage vapor compression type heat pump circulation loop, and the single-stage vapor compression type heat pump circulation loop uses argon as the heat pump system refrigerant. The argon heat pump circulation effectively prevents the direct heat exchange between hydrocarbons and air, reduces the safety risk of accumulated hydrocarbon substances in the liquefied air, and meanwhile, the cold energy transmission heat pump circulation uses a normal-temperature compressor to avoid the use of a low-temperature compressor and improve the economy of the device.

[0046] In addition, the latent heat of argon is higher than that of nitrogen, the gas amount of the argon circulation is small, and the energy consumption is low, so that the normal-temperature compressors are used in each circulation unit of the system, the energy-saving effect of the argon circulation in the existing LNG cold energy air liquefaction system is more excellent than that of the low-temperature compressor, the energy of the air liquefaction system is saved, and the economy and reliability of the system are improved.

[0047] Moreover, the critical temperature and the boiling point of argon under the same pressure are higher than those of nitrogen, and are between those of nitrogen and methane, so that the argon is used as the circulation medium, the system pressure is reduced in the air liquefaction process, the requirement for the pressure resistance of the equipment is reduced, and the energy can be effectively saved.

[0048] It should be noted that, in the single-stage vapor compression heat pump circulation, throttling must be performed first, and then the natural gas compressor is used for pressurization. Figure 4 and Figure 5 The LNG pressure energy is converted into high-grade temperature energy through throttling and pressure increasing, for example, the pressure is reduced to about 115kPa through throttling, and the temperature grade of the LNG is fully utilized, so that the single-stage heat pump circulation can be used to realize air liquefaction.

[0049] In a feasible embodiment of the utility model, the vapor compression cold energy transmission heat pump circulation unit 2 can be cascade type, comprising a methane heat pump circulation loop 21 and an argon heat pump circulation loop 22, forming a two-stage cascade circulation, and adopting methane and argon as heat pump system refrigerant. The two-stage cascade heat pump circulation of two-stage methane and argon can effectively match the change of LNG complex heavy hydrocarbon component phase change temperature, at the same time, the argon heat pump circulation effectively insulates the direct heat exchange between hydrocarbon and air, reduces the safety risk of accumulated hydrocarbon substances in liquefied air, at the same time, the cold energy transmission heat pump circulation adopts normal temperature compressor, avoids the use of low temperature compressor, and improves the economy of the device.

[0050] Specifically, the methane heat pump circulation loop 21 comprises a first compressor 211, a first gas cooler 212, a first heat exchanger 11, a first gas throttler 213 and a fourth heat exchanger 214 to form a loop; the methane is cooled by the first gas cooler 212 and the cooling medium gas cooling circulation unit.

[0051] The argon heat pump circulation loop 22 comprises a second compressor 221, a second gas cooler 222, a fourth heat exchanger 214, a second gas throttler 223 and a third heat exchanger 33 to form a loop; the argon is cooled by the second gas cooler 222 and the cooling medium gas cooling circulation unit 4.

[0052] In another embodiment of the utility model, the krypton heat pump circulation loop and the argon heat pump circulation loop can also be included, krypton / argon is adopted as heat pump system refrigerant, which can better match the LNG gasification temperature curve, low temperature compression is changed into normal temperature compression, and high reliability is achieved.

[0053] In a feasible embodiment of the utility model, the cooling medium gas cooling circulation unit 4 comprises a cooling medium circulation pump 41, a second heat exchanger 12, a cooling medium shunt 42 and a cooling medium collector 43 to form a loop, and the air cooler 32, the first gas cooler 212 and the second gas cooler 222 are arranged in parallel between the cooling medium shunt 42 and the cooling medium collector 43. The cooling medium is usually a solution that is liquid at above -100 DEG C under normal pressure, such as ethylene glycol solution, propylene glycol solution, glycerol solution, salt solution and the like.

[0054] In the above embodiment, the ethylene glycol aqueous solution is used for heat exchange with the gasified LNG, is used for gas cooling in each circulation unit of the system, realizes further utilization of the sensible heat of LNG, reduces the compressor energy consumption of the system, thereby realizing the efficient utilization of cold energy of LNG latent heat and sensible heat in the whole temperature zone in the single technical application scene of air liquefaction separation, and the utility model has great energy saving benefit compared with the conventional pure electric refrigeration liquid air production system and the existing LNG cold energy air liquefaction system.

[0055] As Figure 2 And Figure 4As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade

[0056] As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade Figure 3 As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade

[0057] As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade Figure 1 As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade Figure 5 As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade As shown in a feasible embodiment of the utility model, the LNG pressure regulating device includes LNG throttling device 13 and natural gas compressor 14, LNG throttling device 13 is arranged at the upstream of first heat exchanger 11, and natural gas compressor 14 is arranged at the downstream of second heat exchanger 12. The purpose of such arrangement is that LNG gasification circulating unit throttles first and then boosts pressure, and LNG pressure can be converted into high-grade temperature energy, for example, throttling and pressure reduction to 115kPa, and full use is made of LNG temperature grade

[0058] In a feasible embodiment of the utility model, LNG gasification circulating unit 1 further includes natural gas cooling device 17, natural gas cooling device 17 is arranged at the downstream of natural gas compressor 14, and the outlet of natural gas cooling device 17 is connected to city gas pipe network, and natural gas cooling device 17 is used to cool natural gas to the required temperature.

[0059] In a feasible embodiment of the utility model, air compressor 31 can be a multi-stage compression unit, and air cooler 32 is arranged at the downstream of each compression unit, which can improve air liquefaction efficiency.

[0060] In a feasible embodiment of the utility model, air pressurized liquefaction circulating unit 3 still includes air drying purifier 34, set up between air cooler 32 and third heat exchanger 33, air drying purifier can realize air purification through various ways, make air enter third heat exchanger 33 before through dehydration decarburization treatment, these processes are completed in cold dryer, molecular sieve adsorber respectively, then enter third heat exchanger 33.

[0061] Further, air pressurized liquefaction circulating unit 3 includes air inlet pipeline and liquid air outlet pipeline, air inlet pipeline is connected with the input end of air compressor 31, liquid air outlet pipeline is connected with storage tank, or liquid air outlet pipeline is connected with raw material inlet pipe for air separation, medical care, food processing, oxygen-enriched combustion and carbon capture, energy storage system.

[0062] As Figure 4 The working principle of the embodiment shown as follows: the raw LNG enters the system from the storage tank, is throttled and cooled by LNG throttling device 13, enters first heat exchanger 11 and exchanges heat with argon, LNG is evaporated and argon is condensed to generate liquid argon, the evaporated LNG exchanges heat with argon to recover cold energy, the temperature rises to-14 DEG C, enters first heat exchanger 11 to become normal temperature, then the natural gas is pressurized to 0.4MPa by natural gas compressor 14 and enters the low-pressure gas supply pipe network. The raw air needs to be compressed, dehydrated and decarburized before entering the low-temperature system, and then is compressed to 0.4MPa and 0.8MPa respectively and is cooled. The produced liquid air can select different storage pressure, for next step separation or other use.

[0063] In the description of the utility model embodiment, it needs to be explained that, unless there is definite provision and limitation, the term "connect", "connection" should be broad sense understanding, for example, can be fixed connection, also can be detachable connection, or integral connection, can be mechanical connection, also can be electrical connection, can be directly connected, also can be indirectly connected through intermediate medium. For ordinary skilled in the art, the specific meaning of the above-mentioned terms in the utility model embodiment can be understood according to specific circumstances.

[0064] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "aspects", "specific aspects", or "some aspects" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or aspect are included in at least one embodiment or aspect of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or aspect. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or aspects. In addition, those skilled in the art can combine and combine the different embodiments or aspects described in the present application and the features of the different embodiments or aspects without contradiction.

[0065] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, only the main components in each cycle unit are shown, but not limited to them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of each embodiment of the present application.

Claims

1. A LNG cold energy air liquefaction system based on vapor compression heat pump cycle, characterized in that, The application relates to a LNG gasification cycle unit (1) comprising a first heat exchanger (11), a second heat exchanger (12) and a LNG pressure regulating device; the first heat exchanger (11) is connected with a LNG storage tank; the LNG pressure regulating device is used for increasing the pressure of LNG; A vapor compression type cold energy transmission heat pump cycle unit (2) is used for recycling the low-temperature cold energy of LNG liquid to liquefy air at a lower temperature; An air pressurization liquefaction cycle unit (3) comprises an air compressor (31), an air cooler (32) and a third heat exchanger (33) connected in sequence; and the third heat exchanger (33) is used for heat exchange between air and circulating refrigerant; A coolant gas cooling cycle unit (4) is used for recycling the sensible heat of LNG after gasification and cooling the compressed gas of the vapor compression type cold energy transmission heat pump cycle unit (2) and the air pressurization liquefaction cycle unit (3). The vapor compression type cold energy transmission heat pump cycle unit (2) is a cascade type and comprises a methane heat pump cycle loop (21) and an argon heat pump cycle loop (22); the circulating refrigerants are methane and argon respectively; 2. The LNG cold energy air liquefier system based on a vapor compression heat pump cycle according to claim 1, characterized in that, The methane heat pump cycle loop (21) comprises a first compressor (211), a first gas cooler (212), the first heat exchanger (11), a first gas throttling device (213) and a fourth heat exchanger (214) to form a loop; methane is cooled by the first gas cooler (212) and the coolant gas cooling cycle unit (4); The argon heat pump cycle loop (22) comprises a second compressor (221), a second gas cooler (222), the fourth heat exchanger (214), a second gas throttling device (223) and the third heat exchanger (33) to form a loop; argon is cooled by the second gas cooler (222) and the coolant gas cooling cycle unit (4). The coolant gas cooling cycle unit (4) comprises a coolant circulating pump (41), the second heat exchanger (12), a coolant shunt (42) and a coolant collector (43) to form a loop; the air cooler (32), the first gas cooler (212) and the second gas cooler (222) are arranged in parallel between the coolant shunt (42) and the coolant collector (43).

3. The LNG cold energy air liquefier system based on a vapor compression heat pump cycle according to claim 2, characterized in that, The LNG pressure regulating device comprises a LNG throttling device (13) arranged upstream of the first heat exchanger (11) and a natural gas compressor (14) arranged downstream of the second heat exchanger (12).

4. The LNG cold energy air liquefier system based on a vapor compression heat pump cycle according to any one of claims 1-3, characterized in that, The LNG pressure regulating device comprises a low-temperature pump (15) arranged upstream of the first heat exchanger (11) and a natural gas compressor (14) arranged downstream of the second heat exchanger (12).

5. The LNG cold energy air liquefier system based on a vapor compression heat pump cycle according to any one of claims 1-3, characterized in that, ​ 6. The LNG cold energy air liquefier system based on a vapor compression heat pump cycle according to any one of claims 1-3, characterized in that, The LNG pressure regulating device comprises an LNG throttling device (13), a cryogenic pump (15) and an ejector (16), the LNG throttling device (13) and the cryogenic pump (15) are connected in parallel and are both arranged upstream of the first heat exchanger (11), and the ejector (16) is arranged downstream of the second heat exchanger (12). 7.The LNG cold energy air liquefier system based on a vapor compression heat pump cycle of claim 3, wherein, The cold carrier is a solution that remains in liquid state in the cycle. 8.The LNG cold energy air liquefier system based on a vapor compression heat pump cycle of claim 4, wherein, The LNG gasification cycle unit (1) further comprises a natural gas cooling device (17), the natural gas cooling device (17) is arranged downstream of the natural gas compressor (14), and an outlet of the natural gas cooling device (17) is connected to a city gas pipe network. 9.The LNG cold energy air liquefier system based on a vapor compression heat pump cycle of claim 8, wherein, The air compressor (31) is a multi-stage compression unit, and an air cooler (32) is arranged downstream of each compression unit. 10.The LNG cold energy air liquefier system based on a vapor compression heat pump cycle of claim 8, wherein, The air pressurized liquefaction cycle unit (3) further comprises an air drying purifier (34) arranged between the air cooler (32) and the third heat exchanger (33).

Images