Coupling system for liquefied natural gas re-gasification and liquid air energy storage

Abstract

A coupling system for liquefied natural gas re-gasification and liquid air energy storage. The coupling system comprises a liquefied natural gas re-gasification system and a liquid air energy storage system. The liquefied natural gas re-gasification system comprises: a heat exchanger-natural gas (HX-NG) connected to a liquefied natural gas re-gasification path. The liquid air energy storage system comprises: a heat exchanger-charge (HX-C) connected to a main gas liquefaction path, a heat exchanger-discharge (HX-DC) connected to a liquefied main gas re-gasification path, and a cold dewar (CD), wherein a first heat exchange cycle where cold energy exchange is performed with a first heat exchange medium is formed between the heat exchanger-natural gas and the heat exchanger-charge; and a second heat exchange cycle where cold energy exchange is performed with a second heat exchange medium is formed among the heat exchanger-charge, the cold dewar and the heat exchanger-discharge. In the first heat exchange cycle, a hot end of the heat exchanger-natural gas is connected to a hot end of the heat exchanger-charge, and a cold end of the heat exchanger-natural gas is connected to a cold end of the heat exchanger-charge; and in the second heat exchange cycle, hot ends of the heat exchanger-charge, the cold dewar and the heat exchanger-discharge are connected, and cold ends of the heat exchanger-charge, the cold dewar and the heat exchanger-discharge are connected. In the present invention, regardless of whether the liquid air energy storage system is in a charging working state, a standing working state or a discharging working state, effective coupling utilization of cold energy and heat energy between the liquid air energy storage system and the liquefied natural gas re-gasification system can be realized, improving the effective coupling utilization rate of cold energy and heat energy between the systems.

Description

Coupled system of liquefied natural gas regasification and liquid air energy storage

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. CN202410401294.2 filed on April 3, 2024. The full text of the above-mentioned Chinese patent application is hereby cited as part of this application. Technical Field

[0003] The present invention belongs to the technical field of large-scale energy storage, and in particular relates to a coupling system of liquefied natural gas regasification and liquid air energy storage. Background Art

[0004] Liquid Air Energy Storage (LAES), as a type of energy storage technology, uses cheap valley electricity to absorb air from the environment, and then cools it until it becomes liquid for storage. During peak electricity consumption, the liquid air is released from the tank and pressurized and heated, and then enters the expander to generate work and generate electricity, realizing valley electricity peak utilization. It can play an important role in peak regulation of the power grid, but there will be a loss of cold energy during the charging and discharging process. In order to replenish the lost cold energy, additional electricity is usually required to supplement the cold energy, which is costly.

[0005] In recent years, the proportion of natural gas in energy consumption has steadily increased as a clean energy source. With improvements in natural gas liquefaction technology and reductions in LNG (Liquefied Natural Gas) transportation costs, LNG has gained widespread application and attention. LNG receiving terminals often involve the LNG regasification (RG) process. The regasification of LNG into natural gas releases a significant amount of cold energy, making the coupled application of LAES and LNG-RG systems highly practical and promising.

[0006] At present, scholars and manufacturers at home and abroad have proposed multiple coupling models for the LAES system and the LNG-RG system. However, they have not considered the coupled continuous operation of the LNG-RG system and the LAES system under various working conditions. The coupling system is imperfect, and the effective coupling utilization rate of the cold and heat energy between the systems is low. Summary of the Invention

[0007] In view of this, an object of the present invention is to propose a coupled system of liquefied natural gas regasification and liquid air energy storage to solve the problems in the prior art of imperfect coupling system between LAES system and LNG-RG system and low effective coupling utilization rate of cold energy and heat energy between the systems.

[0008] In some illustrative embodiments, the coupled LNG-RG and LAES system includes an LNG-RG system and a LAES system; the LNG-RG system includes: a natural gas heat exchanger connected to a liquefied natural gas regasification path; the LAES system includes: a cold storage tank, a charging heat exchanger connected to a main gas liquefaction path, and a discharging heat exchanger connected to a liquefied main gas regasification path;

[0009] A first heat exchange cycle using a first heat exchange medium for cold energy exchange is formed between the natural gas heat exchanger and the charging heat exchanger; a second heat exchange cycle using a second heat exchange medium for cold energy exchange is formed between the charging heat exchanger, the cold storage tank, and the discharging heat exchanger;

[0010] Among them, in the first heat exchange cycle, the hot ends and cold ends of the natural gas heat exchanger and the charging heat exchanger are connected respectively; in the second heat exchange cycle, the hot ends and cold ends of the charging heat exchanger, the cold storage tank and the discharge heat exchanger are connected respectively.

[0011] In some optional embodiments, when the LNG-RG system is operating and the LAES system is in a charging condition, a stationary condition, a discharging condition, or a condition change, the first heat exchange medium in the first heat exchange cycle maintains a flow cycle of the cold end of the natural gas heat exchanger, the cold end of the charging heat exchanger, the hot end of the charging heat exchanger, and the hot end of the natural gas heat exchanger; the second heat exchange medium in the second heat exchange cycle exchanges cold energy with the first heat exchange medium in the charging heat exchanger.

[0012] In some optional embodiments, when the LNG-RG system is shut down and the LAES system is in a charging condition, the second heat exchange medium in the second heat exchange cycle circulates in the flow direction of the cold end of the cold storage tank, the cold end of the charging heat exchanger, the hot end of the charging heat exchanger, and the hot end of the cold storage tank; the main gas under the charging condition of the LAES system exchanges cold energy with the second heat exchange medium in the charging heat exchanger.

[0013] In some optional embodiments, when the LNG-RG system is shut down and the LAES system is in a discharge condition, the second heat exchange medium in the second heat exchange cycle circulates in a flow direction of the cold end of the discharge heat exchanger, the cold end of the cold storage tank, the hot end of the cold storage tank, and the hot end of the discharge heat exchanger; the liquefied main gas under the discharge condition of the LAES system exchanges cold energy with the second heat exchange medium in the discharge heat exchanger.

[0014] In some optional embodiments, the cold storage tank includes: a shallow cold tank for storing and releasing shallow cold energy, and a cryogenic tank for storing and releasing deep cold energy; the natural gas heat exchanger includes: a cryogenic natural gas heat exchanger and a shallow cold natural gas heat exchanger arranged in sequence along the liquefied natural gas regasification direction on the liquefied natural gas regasification path; the charging heat exchanger includes: a shallow cold charging heat exchanger and a cryogenic charging heat exchanger arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; the discharge heat exchanger includes: a cryogenic discharge heat exchanger and a shallow cold discharge heat exchanger arranged in sequence along the liquefied main gas regasification direction on the liquefied main gas regasification path; the first heat exchange medium includes: a first shallow cold heat exchange medium and a first cryogenic heat exchange medium; the second heat exchange medium includes: a second shallow cold heat exchange medium and a second cryogenic heat exchange medium.

[0015] In some optional embodiments, the first heat exchange cycle includes: a first shallow cold closed loop for exchanging cold energy between the shallow cold natural gas heat exchanger and the shallow cold charging heat exchanger using a first shallow cold heat exchange medium; and a first deep cold closed loop for exchanging cold energy between the deep cold natural gas heat exchanger and the deep cold charging heat exchanger using the first deep cold heat exchange medium; wherein, in the first shallow cold closed loop, the hot ends of the shallow cold natural gas heat exchanger and the shallow cold charging heat exchanger are respectively connected, and the cold ends of the deep cold natural gas heat exchanger and the deep cold charging heat exchanger are respectively connected in the first deep cold closed loop;

[0016] In some optional embodiments, the second heat exchange cycle includes: a second shallow cold closed loop for exchanging cold energy between the shallow cold charging heat exchanger, the shallow cold tank, and the shallow cold discharge heat exchanger using a second shallow cold heat exchange medium; and a second deep cold closed loop for exchanging cold energy between the deep cold charging heat exchanger, the deep cold tank, and the deep cold discharge heat exchanger using a second deep cold heat exchange medium; wherein, in the second shallow cold closed loop, the hot ends of the shallow cold charging heat exchanger, the shallow cold tank, and the shallow cold discharge heat exchanger are respectively connected, and the cold ends of the deep cold charging heat exchanger, the deep cold tank, and the deep cold discharge heat exchanger are respectively connected in the second deep cold closed loop.

[0017] In some optional embodiments, the shallow cooling charging heat exchanger includes: a first shallow cooling charging heat exchanger and a second shallow cooling charging heat exchanger arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path;

[0018] The shallow-cooled natural gas heat exchanger and the first shallow-cooled charging heat exchanger form the first shallow-cooled closed circuit for exchanging cold energy with the first shallow-cooled heat exchange medium; the first shallow-cooled charging heat exchanger, the second shallow-cooled charging heat exchanger, the shallow-cooled tank, and the shallow-cooled discharge heat exchanger form the second shallow-cooled closed circuit for exchanging cold energy with the second shallow-cooled heat exchange medium.

[0019] Among them, the hot ends and cold ends of the shallow-cooled natural gas heat exchanger and the first shallow-cooled charging heat exchanger in the first shallow-cooled closed loop are connected respectively; the hot ends and cold ends of the first shallow-cooled charging heat exchanger, the second shallow-cooled charging heat exchanger, the shallow-cooled tank and the shallow-cooled discharge heat exchanger in the second shallow-cooled closed loop are connected respectively.

[0020] In some optional embodiments, when the LNG-RG system is running and the LAES system is in a charging condition, a stationary condition, a discharging condition or a condition change, the first cryogenic heat exchange medium in the first cryogenic closed loop maintains a flow circulation of the cryogenic natural gas heat exchanger cold end, the cryogenic charging heat exchanger cold end, the cryogenic charging heat exchanger hot end, and the cryogenic natural gas heat exchanger hot end; at the same time, the first shallow cooling heat exchange medium in the first shallow cooling closed loop maintains a flow circulation of the shallow cooling natural gas heat exchanger cold end, the first shallow cooling charging heat exchanger cold end, the first shallow cooling charging heat exchanger hot end, and the shallow cooling natural gas heat exchanger hot end.

[0021] In some optional embodiments, when the LNG-RG system is running and the LAES system is in the charging condition, the second shallow cooling heat exchange medium in the second shallow cooling closed loop circulates in the flow direction of the first shallow cooling charging heat exchanger hot end, the shallow cooling tank hot end, the shallow cooling tank cold end, and the first shallow cooling charging heat exchanger cold end; and, circulates in the flow direction of the shallow cooling tank cold end, the second shallow cooling charging heat exchanger cold end, the second shallow cooling charging heat exchanger hot end, and the cold end of the cold storage tank; at the same time, the second deep cooling heat exchange medium in the second deep cooling closed loop circulates in the flow direction of the deep cooling charging heat exchanger hot end, the deep cooling tank hot end, the deep cooling tank cold end, and the deep cooling charging heat exchanger cold end; the main gas under the charging condition of the LAES system exchanges cold energy with the corresponding heat exchange medium in the first shallow cooling charging heat exchanger, the second shallow cooling charging heat exchanger, and the deep cooling charging heat exchanger in turn.

[0022] In some optional embodiments, when the LNG-RG system is running and the LAES system is in a static condition, the second shallow cooling heat exchange medium in the second shallow cooling closed loop circulates in the flow direction of the first shallow cooling charging heat exchanger cold end, the shallow cooling tank cold end, the shallow cooling tank hot end, and the first shallow cooling charging heat exchanger hot end to replenish shallow cooling energy for the shallow cooling tank; at the same time, the second deep cooling heat exchange medium in the second deep cooling closed loop circulates in the flow direction of the deep cooling charging heat exchanger cold end, the deep cooling tank cold end, the deep cooling tank hot end, and the deep cooling charger hot end to replenish deep cooling energy for the deep cooling tank.

[0023] In some optional embodiments, when the LNG-RG system is running and the LAES system is in the discharging condition, the second shallow cold heat exchange medium in the second shallow cold closed loop circulates in the flow direction of the first shallow cold charging heat exchanger cold end, the shallow cold tank cold end, the shallow cold tank hot end, and the first shallow cold charging heat exchanger hot end; and, circulates in the flow direction of the shallow cold discharge heat exchanger cold end, the shallow cold tank cold end, the shallow cold tank hot end, and the shallow cold discharge heat exchanger hot end to replenish shallow cold energy for the shallow cold tank; at the same time, the second deep cold heat exchange medium in the second deep cold closed loop circulates in the flow direction of the deep cold charging heat exchanger cold end, the deep cold tank cold end, the deep cold tank hot end, and the deep cold charging heat exchanger hot end; and, circulates in the flow direction of the deep cold discharge heat exchanger cold end, the deep cold tank cold end, the deep cold tank hot end, and the deep cold discharge heat exchanger hot end to replenish deep cold energy for the deep cold tank;

[0024] The liquefied main gas under the LAES system discharge condition exchanges cold energy with the corresponding heat exchange medium in the deep-cold discharge heat exchanger and the shallow-cold discharge heat exchanger in turn.

[0025] In some optional embodiments, the LAES system further includes: a compressor, a cryogenic expander, a liquid-gas separator and a liquid air storage tank arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; wherein, the first shallow cold charging heat exchanger is arranged in front of the main gas inlet of the compressor, and the second shallow cold charging heat exchanger is arranged between the compressor and the cryogenic expander; the deep cold charging heat exchanger is arranged between the second shallow cold charging heat exchanger and the cryogenic expander.

[0026] In some optional embodiments, the LAES system further includes: an ultra-cold charging heat exchanger connected to both the main gas liquefaction path and the return main gas path; wherein the ultra-cold charging heat exchanger is located after the cryogenic charging heat exchanger along the main gas liquefaction direction on the main gas liquefaction path, and is located before the cryogenic charging heat exchanger along the return main gas direction on the return main gas path, for cascade recovery and use of the ultra-cold energy and cryogenic energy of the return main gas.

[0027] In some optional embodiments, the coupling system further includes: a gas phase passage running through the shallow natural gas heat exchanger and the cryogenic natural gas heat exchanger, for transporting purified ambient air through the gas phase passage and exchanging cold energy with the LNG-RG system in the shallow natural gas heat exchanger and the cryogenic natural gas heat exchanger in sequence when the LNG-RG system is operating and the LAES system is shut down or the cold storage tank has excess cold energy.

[0028] Compared with the existing technology, this application has the following advantages:

[0029] In this embodiment of the present invention, the LNG-RG system's operating conditions are not only coupled with the LAES system's charging conditions, but also with the LAES system's stationary and discharging conditions. This allows for effective coupling and utilization of cooling and thermal energy between the LAES system and the LNG-RG system, regardless of whether the LAES system is in any of the charging, stationary, or discharging conditions. This improves the coupling system and increases the effective coupling utilization of cooling and thermal energy between the systems. Furthermore, the LNG-RG system is guaranteed to operate continuously under various coupling conditions with the LAES system, allowing either the LAES system or the LNG-RG system to switch operating conditions based on their actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a structural example 1 of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention;

[0031] FIG2 is an example of a first coupling working condition of the coupling system in an embodiment of the present invention;

[0032] FIG3 is an example 1 of a second coupling working condition of the coupling system in an embodiment of the present invention;

[0033] FIG4 is an example 1 of a third coupling working condition of the coupling system in an embodiment of the present invention;

[0034] FIG5 is an example 1 of a fourth coupling working condition of the coupling system in an embodiment of the present invention;

[0035] FIG6 is an example 1 of a fifth coupling working condition of the coupling system in an embodiment of the present invention;

[0036] FIG7 is a second example of a fifth coupling working condition of the coupling system in an embodiment of the present invention;

[0037] FIG8 is a second structural example of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention;

[0038] FIG9 is a third structural example of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention;

[0039] FIG10 is a second example of a first coupling working condition of the coupling system in an embodiment of the present invention;

[0040] FIG11 is a second example of a second coupling working condition of the coupling system in an embodiment of the present invention;

[0041] FIG12 is a second example of a third coupling working condition of the coupling system in an embodiment of the present invention;

[0042] FIG13 is a third example of the first coupling working condition of the coupling system according to an embodiment of the present invention;

[0043] FIG14 is a fourth structural example of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention;

[0044] FIG15 is a fourth example of the first coupling working condition of the coupling system according to an embodiment of the present invention;

[0045] FIG16 is a second example of a fourth coupling operating condition of the coupling system according to an embodiment of the present invention;

[0046] FIG17 is a fifth structural example of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention.

[0047] Figure symbols: Natural gas heat exchanger HX-NG (Heat Exchanger-Natural Gas), deep cold natural gas heat exchanger HX-NG1 (Heat Exchanger-Natural Gas 1), shallow cold natural gas heat exchanger HX-NG2 (Heat Exchanger-Natural Gas 2); Charging heat exchanger HX-C (Heat Exchanger-Charge), shallow cold charging heat exchanger HX-SC (Heat Exchanger -Shallow Cold), deep cold charging heat exchanger HX-CB (Hear Exchanger-Cold Box), first shallow cold charging heat exchanger HX-SC1 (Heat Exchanger-Shallow Cold 1), second shallow cold charging heat exchanger HX-SC2 (Heat Exchanger-Shallow Cold 2), third shallow cold charging heat exchanger HX-SC3 (Heat Exchanger-Shallow Cold 3), fourth shallow cold charging heat exchanger HX-SC4 (Heat Exchanger-Shallow Cold 4); Ultra-cold charging heat exchanger HX-UC (Heat Exchanger-Ultra Cold); Cold storage tank CD (Cold Dewar), shallow cold tank SCD (Shallow Cold Dewar), first shallow cold tank SCD1 (Shallow Cold Dewar 1), second shallow cold tank SCD2 (Shallow Cold Dewar 2), deep cold tank DCD (Deep Cold Dewar), first deep cold tank DCD1 (Deep Cold Dewar 1), second deep cold tank DCD2 (Deep Cold Dewar 2); Discharge heat exchanger HX-DC (Heat Exchanger-Discharge), deep cold discharge heat exchanger HX-DC1 (Heat Exchanger-Discharge 1), shallow cold discharge heat exchanger HX-DC2 (Heat Exchanger-Discharge 2);Compressor C (Compressor), first-stage compressor C1 (Compressor 1), second-stage compressor C2 (Compressor 1), third-stage compressor C3 (Compressor 1), cryogenic expander CE (Cryogenic Expander), liquid air separator LAS (Liquid Air Separator), liquid air storage tank LAD (Liquid Air Dewar), cryogenic pump CP (Cryogenic Pump), expander E (Expander). DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that the various technical features in the embodiments of the present invention can be combined with each other without conflict.

[0050] Terminology Notes:

[0051] LNG-RG system, liquefied natural gas regasification system, is used to realize the conversion of liquefied natural gas (LNG) into natural gas (NG). It has a liquefied natural gas regasification path. LNG is converted into NG in the process of releasing cold energy (and absorbing heat energy) on the liquefied natural gas regasification path.

[0052] The LAES system, a liquid air energy storage system, is used to convert main gas (air) into liquefied main gas (liquid air) for energy storage through electric energy during the charging process, and to generate electric energy in the process of converting liquefied main gas into regasified main gas during the discharge process. It has a main gas liquefaction path and a liquefied main gas regasification path. The main gas is converted into liquefied main gas in the process of absorbing cold energy (and releasing heat energy at the same time) on the main gas liquefaction path, and the liquefied main gas is converted into regasified main gas in the process of releasing cold energy (and absorbing heat energy) on the liquefied main gas regasification path.

[0053] Under the charging condition of the LAES system, the main gas refers to the part of air that is purified, passes through the main gas liquefaction path, and finally becomes liquid air, excluding the return air that needs to recover cold energy; under the discharging condition of the LAES system, the liquefied main gas refers to liquid air and regasified liquid air.

[0054] In an embodiment of the present invention, a coupled system of liquefied natural gas regasification (LNG-RG) and liquid air energy storage (LAES) is disclosed. Specifically, as shown in FIG1 , FIG1 is a structural example 1 of a coupled system of an LNG-RG system and a LAES system in an embodiment of the present invention;

[0055] The coupled system includes an LNG-RG system and a LAES system. The LNG-RG system includes a natural gas heat exchanger HX-NG connected to the liquefied natural gas regasification path. The LAES system includes a charging heat exchanger HX-C connected to the main gas liquefaction path, a discharging heat exchanger HX-DC connected to the liquefied main gas regasification path, and a cold storage tank CD.

[0056] The natural gas heat exchanger HX-NG and the charging heat exchanger HX-C form a first heat exchange cycle for exchanging cold energy using the first heat exchange medium; the charging heat exchanger HX-C, the cold storage tank CD and the discharge heat exchanger HX-DC form a second heat exchange cycle for exchanging cold energy using the second heat exchange medium;

[0057] Among them, in the first heat exchange cycle, the hot ends and cold ends of the natural gas heat exchanger HX-NG and the charging heat exchanger HX-C are connected respectively; in the second heat exchange cycle, the hot ends and cold ends of the charging heat exchanger HX-C, the cold storage tank CD and the discharge heat exchanger HX-DC are connected respectively.

[0058] In some embodiments, the main gas liquefaction path of the LAES system includes: an air purification device (not shown), a compressor C, a cryogenic expander CE, a gas-liquid separator LAS, and a liquid air storage tank LAD, all connected in sequence. A charging heat exchanger HX-C can be located between the compressor C and the cryogenic expander CE. The liquefied main gas regasification path of the LAES system includes: a liquid air storage tank LAD, a cryogenic pump CP, and an expander E, all connected in sequence. A discharging heat exchanger HX-DC can be located between the cryogenic pump CP and the expander E. The liquid air storage tank LAD for both the main gas liquefaction path and the liquefied main gas regasification path is the same.

[0059] The LAES system in the existing technology usually configures a heat storage tank to recover and store the compression heat energy of the main gas compressed by the compressor unit, and uses it to heat and expand the regasified main gas under the discharge condition of the LAES system. However, the actual value of this compression heat energy is low, and the heat storage and maintenance costs are high. It can be replaced by heat energy provided by an external heat source.

[0060] As shown in FIG2 , FIG2 is an example 1 of a first coupling working condition of a coupling system in an embodiment of the present invention, which is applicable to the structural example 1 of the coupling system shown in FIG1 ;

[0061] In the first coupling condition, when the LNG-RG system is operating and the LAES system is in the charging condition, the cold energy generated by the LNG-RG system and the cold energy stored in the LAES system are jointly output to the main gas in the LAES system charging condition, thereby achieving LNG regasification and main gas liquefaction;

[0062] Specifically, since the charging heat exchanger HX-C is connected to the main gas liquefaction path of the LAES system, in the first heat exchange cycle, the cold energy generated by LNG regasification during the operation of the LNG-RG system can be transferred to the main gas entering the charging heat exchanger HX-C under the charging condition of the LAES system through the first heat exchange medium, and the heat energy of the main gas entering the charging heat exchanger HX-C under the charging condition of the LAES system can be transferred to the LNG-RG system; at the same time, in the second heat exchange cycle, the cold energy stored in the cold storage tank CD of the LAES system can be transferred to the main gas entering the charging heat exchanger HX-C under the charging condition of the LAES system through the second heat exchange medium, and the heat energy of the main gas entering the charging heat exchanger HX-C under the charging condition of the LAES system can be transferred to the cold storage tank CD of the LAES system itself, so that the cold energy generated by the operation of the LNG-RG system and the cold energy stored in the LAES system itself are jointly output to the main gas under the charging condition of the LAES system, thereby achieving the effect of regasification of LNG and liquefaction of the main gas.

[0063] Furthermore, at this time, the first heat exchange medium in the first heat exchange cycle circulates in the flow direction of the natural gas heat exchanger HX-NG cold end, the charging heat exchanger HX-C cold end, the charging heat exchanger HX-C hot end, and the natural gas heat exchanger HX-NG hot end; the second heat exchange medium in the second heat exchange cycle circulates in the flow direction of the cold end of the cold storage tank CD, the cold end of the charging heat exchanger HX-C, the hot end of the charging heat exchanger HX-C, and the hot end of the cold storage tank CD.

[0064] As shown in FIG3 , FIG3 is a second coupling working condition example 1 of the coupling system in an embodiment of the present invention, which is applicable to the structural example 1 of the coupling system shown in FIG1 ;

[0065] In the second coupling condition, when the LNG-RG system is operating and the LAES system is in a static condition, the cold energy generated by the LNG-RG system is output to the LAES system for storage, realizing LNG regasification and cold storage of the LAES system.

[0066] Specifically, in the first heat exchange cycle, the cold energy generated by LNG regasification during operation of the LNG-RG system is transferred through the first heat exchange medium to the second heat exchange medium in the second heat exchange cycle in the charging heat exchanger HX-C. The second heat exchange medium in the second heat exchange cycle then further transfers the cold energy to the cold storage tank CD for storage. Conversely, after transferring the cold energy to the cold storage tank CD, the second heat exchange medium, which loses its cold energy and then heats up, transfers heat energy to the first heat exchange medium in the first heat exchange cycle in the charging heat exchanger HX-C, thereby allowing the LNG in the LNG-RG system to absorb heat energy and achieve regasification.

[0067] Furthermore, at this time, the first heat exchange medium in the first heat exchange cycle circulates in the flow direction of the natural gas heat exchanger HX-NG cold end, the charging heat exchanger HX-C cold end, the charging heat exchanger HX-C hot end, and the natural gas heat exchanger HX-NG hot end; the second heat exchange medium in the second heat exchange cycle can circulate in the flow direction of the charging heat exchanger HX-C cold end, the cold end of the cold storage tank CD, the hot end of the cold storage tank CD, and the hot end of the charging heat exchanger HX-C.

[0068] The static operating condition of the LAES system in the embodiment of the present invention includes the static operating condition after the LAES system is charged and the static operating condition after the LAES system is discharged.

[0069] As shown in FIG4 , FIG4 is a third coupling working condition example 1 of the coupling system in an embodiment of the present invention, which is applicable to the structural example 1 of the coupling system shown in FIG1 ;

[0070] In the third coupling condition, when the LNG-RG system is operating and the LAES system is in the discharge condition, the cold energy generated by the LNG-RG system and the cold energy generated by the LAES system in the discharge condition are output to the LAES system for storage, realizing the regasification of LNG, the regasification of liquefied main gas and the cold storage of the LAES system.

[0071] Specifically, in the first heat exchange cycle, the cold energy generated by LNG regasification during operation of the LNG-RG system can be transferred to the second heat exchange medium in the charging heat exchanger HX-C in the second heat exchange cycle through the first heat exchange medium, and then the cold energy is further transferred to the cold storage tank CD through the second heat exchange medium in the second heat exchange cycle for storage; conversely, after transferring the cold energy to the cold storage tank CD, the second heat exchange medium, which loses the cold energy and then heats up, transfers heat energy to the first heat exchange medium in the first heat exchange cycle in the charging heat exchanger HX-C, thereby allowing the LNG of the LNG-RG system to absorb heat energy and achieve regasification; at the same time, in the second heat exchange cycle, the cold energy generated by the regasification of the liquefied main gas under the discharge condition of the LAES system is also transferred to the cold storage tank CD through the second heat exchange medium for storage, and conversely, after transferring the cold energy to the cold storage tank CD, the second heat exchange medium, which loses the cold energy and then heats up, transfers heat energy to the liquefied main gas in the discharge heat exchanger HX-C, thereby allowing the liquefied main gas under the discharge condition of the LAES system to absorb heat energy and achieve regasification.

[0072] Furthermore, at this time, the first heat exchange medium in the first heat exchange cycle circulates in the flow direction of the natural gas heat exchanger HX-NG cold end, the charging heat exchanger HX-C cold end, the charging heat exchanger HX-C hot end, and the natural gas heat exchanger HX-NG hot end; the second heat exchange medium in the second heat exchange cycle can circulate in the flow direction of the charging heat exchanger HX-C cold end, the cold end of the cold storage tank CD, the hot end of the cold storage tank CD, and the hot end of the charging heat exchanger HX-C, as well as in the flow direction of the discharge heat exchanger HX-DC cold end, the cold end of the cold storage tank CD, the hot end of the cold storage tank CD, and the hot end of the discharge heat exchanger HX-DC.

[0073] When the LNG-RG system is running and the LAES system is in charging condition, static condition, discharging condition or condition change, the first heat exchange medium in the first heat exchange cycle maintains a flow cycle of the natural gas heat exchanger HX-NG cold end, the charging heat exchanger HX-C cold end, the charging heat exchanger HX-C hot end, and the natural gas heat exchanger HX-NG hot end; the second heat exchange medium in the second heat exchange cycle exchanges cold energy with the first heat exchange medium in the charging heat exchanger HX-C.

[0074] In the coupled system of the present embodiment, since both the first and second heat exchange cycles involve the charging heat exchanger, the natural gas heat exchanger, the charging heat exchanger, the heat storage tank, and the discharge heat exchanger can transfer cold and heat energy between them via the first and / or second heat exchange mediums. This allows for the effective coupled utilization of cold and heat energy under the respective operating conditions of the LNG-RG and LAES systems, improving the coupled system and increasing the effective coupled utilization of cold and heat energy between the systems. Furthermore, the LNG-RG system is guaranteed to operate continuously under various coupled operating conditions with the LAES system, allowing the LAES or LNG-RG system to switch operating conditions based on their actual needs.

[0075] In addition, when the LNG-RG system is operating and the LAES system is in charging, stationary, discharging, or a change in operating condition, the flow direction of the first heat exchange medium in the first heat exchange cycle remains unchanged. When the LNG-RG system is operating and the LAES system is in charging, the second heat exchange medium in the second heat exchange cycle flows from the cold end of the cold storage tank, consumes its own cold energy to exchange cold energy with the main gas, and then flows back from the hot end of the cold storage tank. When the LNG-RG system is operating and the LAES system is in stationary or discharging conditions, the second heat exchange medium flows from the hot end of the cold storage tank, absorbs cold energy from the LNG-RG system and / or cold energy from the liquefied main gas regasification process, and then flows back from the cold end of the cold storage tank.

[0076] In some embodiments, the natural gas regasification path, the main gas liquefaction path, the liquefied main gas regasification path, the first heat exchange cycle, and the second heat exchange cycle in the embodiments of the present invention can all be independent paths and are not interconnected. Some heat exchangers in the embodiments of the present invention have at least two independent heat exchange pipes. For example, a natural gas heat exchanger supports cold energy exchange between LNG and the first heat exchange medium. It should have at least two independent heat exchange pipes and meet the requirement that effective cold energy exchange can be performed between the two independent heat exchange pipes. For the charging heat exchanger, it supports cold energy exchange between the first heat exchange medium, the main gas under charging conditions, and the second heat exchange medium. It should have at least three independent heat exchange pipes. Some embodiments of the present invention may have some changes to the above, but the principles remain the same and will not be elaborated on.

[0077] As shown in FIG5 , FIG5 is a fourth coupling working condition example 1 of the coupling system in an embodiment of the present invention, which is applicable to the structural example 1 of the coupling system shown in FIG1 ;

[0078] In some embodiments, the LAES system of the present invention further includes a gas phase passageway extending through the natural gas heat exchanger HX-NG. This passageway is used to transport purified ambient air through the gas phase passageway and exchange cold energy with the LNG-RG system within the natural gas heat exchanger when the LNG-RG system is operating and the LAES system is shut down, or when the cold storage tank has excess cold energy. This gas phase passageway can be independent of the natural gas regasification path and heat exchange circulation path within the natural gas heat exchanger, or it can be directly formed by utilizing the heat exchange circulation path within the natural gas heat exchanger.

[0079] In some embodiments, the coupled system of liquefied natural gas regasification and liquid air energy storage in the embodiments of the present invention can cut off the cold energy exchange between the LNG-RG system and the LAES system when the LNG-RG system is shut down. That is, by cutting off the cold energy exchange between the two systems, the two systems are decoupled, and the LAES system can operate independently with its own independent system architecture at this time.

[0080] As shown in FIG6 , FIG6 is a fifth coupling operating condition example 1 of the coupling system in an embodiment of the present invention, which is applicable to the structural example 1 of the coupling system shown in FIG1 ;

[0081] When the LNG-RG system is shut down and the LAES system is in the charging condition, the second heat exchange medium in the second heat exchange cycle circulates in the flow direction of the cold end of the cold storage tank CD, the cold end of the charging heat exchanger HX-C, the hot end of the charging heat exchanger HX-C, and the hot end of the cold storage tank CD; the main gas under the charging condition of the LAES system exchanges cold energy with the second heat exchange medium in the charging heat exchanger HX-C; that is, when the LAES system is in the charging condition, the second heat exchange medium in the second heat exchange cycle transfers the cold energy of the cold storage tank CD to the main gas under the charging condition of the LAES system, thereby cooling the main gas, and transferring the heat energy of the main gas under the charging condition of the LAES system to the cold storage tank.

[0082] As shown in FIG. 7 , FIG. 7 is a fifth coupling operating condition example 2 of the coupling system in an embodiment of the present invention, which is applicable to the structural example 1 of the coupling system shown in FIG. 1 ;

[0083] When the LNG-RG system is shut down and the LAES system is in the discharge condition, the second heat exchange medium in the second heat exchange cycle circulates in the flow direction of the discharge heat exchanger HX-DC cold end, the cold end of the cold storage tank CD, the hot end of the cold storage tank CD, and the hot end of the discharge heat exchanger HX-DC; the liquefied main gas under the discharge condition of the LAES system exchanges cold energy with the second heat exchange medium in the discharge heat exchanger HX-DC; that is, when the LAES system is in the discharge condition, the second heat exchange medium in the second heat exchange cycle transfers the cold energy of the regasification of the liquefied main gas under the discharge condition of the LAES system to the cold storage tank for storage, and transfers the heat energy of the cold storage tank to the liquefied main gas under the discharge condition of the LAES system, thereby realizing the regasification of the liquefied main gas.

[0084] As shown in FIG8 , FIG8 is a second structural example of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention;

[0085] In this embodiment, the cold energy involved between the two systems is divided into deep cold energy and shallow cold energy according to the quality of the cold energy, where the quality of deep cold energy is higher than that of shallow cold energy; by dividing the cold energy into deep cold energy and shallow cold energy, the cold energy exchange between the two systems is further divided into shallow cold energy exchange and deep cold energy exchange.

[0086] Specifically,

[0087] Cold storage tanks CD include: shallow cold tanks SCD for storing and releasing shallow cold energy, and deep cold tanks DCD for storing and releasing deep cold energy;

[0088] The natural gas heat exchanger HX-NG includes: a deep-cold natural gas heat exchanger HX-NG1 and a shallow-cold natural gas heat exchanger HX-NG2 arranged in sequence along the liquefied natural gas regasification path;

[0089] The charging heat exchanger HX-C includes: a shallow-cooling charging heat exchanger HX-SC and a deep-cooling charging heat exchanger HX-CB, which are arranged in sequence along the main gas liquefaction path;

[0090] The discharge heat exchanger HX-DC includes: a deep-cold discharge heat exchanger HX-DC1 and a shallow-cold discharge heat exchanger HX-DC2 arranged in sequence along the liquefied main gas regasification path;

[0091] The first heat exchange medium includes: a first shallow heat exchange medium and a first deep heat exchange medium; the second heat exchange medium includes: a second shallow heat exchange medium and a second deep heat exchange medium;

[0092] The first heat exchange cycle includes: a first shallow cold closed loop for exchanging cold energy between the shallow cold natural gas heat exchanger HX-NG2 and the shallow cold charging heat exchanger HX-SC using a first shallow cold heat exchange medium; and a first deep cold closed loop for exchanging cold energy between the deep cold natural gas heat exchanger HX-NG1 and the deep cold charging heat exchanger HX-CB using the first deep cold heat exchange medium; wherein, in the first shallow cold closed loop, the hot ends of the shallow cold natural gas heat exchanger HX-NG2 and the shallow cold charging heat exchanger HX-SC are respectively connected, and the cold ends are respectively connected; in the first deep cold closed loop, the hot ends of the deep cold natural gas heat exchanger HX-NG1 and the deep cold charging heat exchanger HX-CB are respectively connected, and the cold ends are respectively connected;

[0093] The second heat exchange cycle includes: a second shallow cold closed loop for exchanging cold energy between the shallow cold charging heat exchanger HX-SC, the shallow cold tank SCD, and the shallow cold discharge heat exchanger HX-DC2 using a second shallow cold heat exchange medium; and a second deep cold closed loop for exchanging cold energy between the deep cold charging heat exchanger HX-CB, the deep cold tank DCD, and the deep cold discharge heat exchanger HX-DC1 using a second deep cold heat exchange medium; wherein, in the second shallow cold closed loop, the hot ends of the shallow cold charging heat exchanger HX-SC, the shallow cold tank SCD, and the shallow cold discharge heat exchanger HX-DC2 are respectively connected, and the cold ends are respectively connected; in the second deep cold closed loop, the hot ends of the deep cold charging heat exchanger HX-CB, the deep cold tank DCD, and the deep cold discharge heat exchanger HX-DC1 are respectively connected, and the cold ends are respectively connected.

[0094] The first shallow heat exchange medium and the second shallow heat exchange medium in the embodiment of the present invention can use the same or different heat exchange media, as long as they maintain a stable fluid state within the defined shallow cold energy temperature range; preferably, the first shallow heat exchange medium and the second shallow heat exchange medium can use methanol; similarly, the first deep cold heat exchange medium and the second deep cold heat exchange medium can use the same or different heat exchange media, as long as they maintain a stable fluid state within the defined deep cold energy temperature range; preferably, the first deep cold heat exchange medium and the second deep cold heat exchange medium can use propane.

[0095] As shown in FIG9 , FIG9 is a structural example 3 of the coupling system of the LNG-RG system and the LAES system according to an embodiment of the present invention;

[0096] In some embodiments, the shallow cooling charging heat exchanger HX-SC in the embodiments of the present invention includes: a first shallow cooling charging heat exchanger HX-SC1 and a second shallow cooling charging heat exchanger HX-SC2 arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; wherein, a first shallow cooling closed loop for exchanging cold energy using a first shallow cooling heat exchange medium is formed between the shallow cooling natural gas heat exchanger HX-NG2 and the first shallow cooling charging heat exchanger HX-SC1; a second shallow cooling closed loop for exchanging cold energy using a second shallow cooling heat exchange medium is formed between the first shallow cooling charging heat exchanger HX-SC1, the second shallow cooling charging heat exchanger HX-SC2, the shallow cooling tank SCD, and the shallow cooling discharge heat exchanger HX-DC2;

[0097] Among them, the hot ends and cold ends are connected respectively between the shallow-cooled natural gas heat exchanger HX-NG2 and the first shallow-cooled charging heat exchanger HX-SC1 in the first shallow-cooled closed loop; the hot ends and cold ends are connected respectively between the first shallow-cooled charging heat exchanger HX-SC1, the second shallow-cooled charging heat exchanger HX-SC2, the shallow-cooled tank SCD and the shallow-cooled discharge heat exchanger HX-DC2 in the second shallow-cooled closed loop.

[0098] The following example shows the operating conditions of the coupled system after dividing the cooling energy into shallow cooling energy and deep cooling energy:

[0099] When the LNG-RG system is running and the LAES system is in charging condition, static condition, discharging condition or condition change, the first cryogenic heat exchange medium in the first cryogenic closed loop maintains a flow circulation of the cryogenic natural gas heat exchanger HX-NG1 cold end, the cryogenic charging heat exchanger HX-CB cold end, the cryogenic charging heat exchanger HX-CB hot end, and the cryogenic natural gas heat exchanger HX-NG1 hot end; at the same time, the first shallow cooling heat exchange medium in the first shallow cooling closed loop maintains a flow circulation of the shallow cooling natural gas heat exchanger HX-NG2 cold end, the first shallow cooling charging heat exchanger HX-SC1 cold end, the first shallow cooling charging heat exchanger HX-SC1 hot end, and the shallow cooling natural gas heat exchanger HX-NG2 hot end.

[0100] As shown in FIG10 , FIG10 is a second example of a first coupling working condition of the coupling system in an embodiment of the present invention, which is applicable to the third structural example of the coupling system shown in FIG9 ;

[0101] When the LNG-RG system is running and the LAES system is in the charging condition, the second shallow cooling heat exchange medium in the second shallow cooling closed loop circulates in the direction of the hot end of the first shallow cooling charging heat exchanger HX-SC1, the hot end of the shallow cooling tank SCD, the cold end of the shallow cooling tank SCD, and the cold end of the first shallow cooling charging heat exchanger HX-SC1; and, in the direction of the cold end of the shallow cooling tank SCD, the cold end of the second shallow cooling charging heat exchanger HX-SC2, the hot end of the second shallow cooling charging heat exchanger HX-SC2, and the hot end of the shallow cooling tank SCD. flow direction circulation; at the same time, the second cryogenic heat exchange medium in the second cryogenic closed loop circulates in the flow direction of the cryogenic charging heat exchanger HX-CB hot end, the cryogenic tank DCD hot end, the cryogenic tank DCD cold end, and the cryogenic charging heat exchanger HX-CB cold end; among them, the main gas under the charging condition of the LAES system exchanges cold energy with the corresponding heat exchange medium in the first shallow cooling charging heat exchanger HX-SC1, the second shallow cooling charging heat exchanger HX-SC2, and the deep cooling charging heat exchanger HX-CB in turn.

[0102] As shown in FIG11 , FIG11 is a second coupling working condition example 2 of the coupling system in an embodiment of the present invention, which is applicable to the structural example 3 of the coupling system shown in FIG9 ;

[0103] When the LNG-RG system is running and the LAES system is in a static condition, the second shallow cooling heat exchange medium in the second shallow cooling closed loop circulates through the cold end of the first shallow cooling charging heat exchanger HX-SC1, the cold end of the shallow cooling tank SCD, the hot end of the shallow cooling tank SCD, and the hot end of the first shallow cooling charging heat exchanger HX-SC1 to replenish shallow cooling energy for the shallow cooling tank SCD; at the same time, the second deep cooling heat exchange medium in the second deep cooling closed loop circulates through the cold end of the deep cooling charging heat exchanger HX-CB, the cold end of the deep cooling tank DCD, the hot end of the deep cooling tank DCD, and the hot end of the deep cooling charging heat exchanger HX-CB to replenish deep cooling energy for the deep cooling tank DCD.

[0104] As shown in FIG12 , FIG12 is a second example of a third coupling working condition of the coupling system in an embodiment of the present invention, which is applicable to the third structural example of the coupling system shown in FIG9 ;

[0105] When the LNG-RG system is running and the LAES system is in the discharge condition, the second shallow cooling heat exchange medium in the second shallow cooling closed loop circulates in the direction of the first shallow cooling charging heat exchanger HX-SC1 cold end, the shallow cooling tank SCD cold end, the shallow cooling tank SCD hot end, and the first shallow cooling charging heat exchanger HX-SC1 hot end; and, circulates in the direction of the shallow cooling discharge heat exchanger HX-DC2 cold end, the shallow cooling tank SCD cold end, the shallow cooling tank SCD hot end, and the shallow cooling discharge heat exchanger HX-DC2 hot end to replenish the shallow cooling energy for the shallow cooling tank SCD; at the same time, the second deep cooling heat exchange medium in the second deep cooling closed loop The heat medium circulates through the cold end of the cryogenic charging heat exchanger HX-CB, the cold end of the cryogenic tank DCD, the hot end of the cryogenic tank DCD, and the hot end of the cryogenic charging heat exchanger HX-CB; and, circulates through the cold end of the cryogenic discharge heat exchanger HX-DC1, the cold end of the cryogenic tank DCD, the hot end of the cryogenic tank DCD, and the hot end of the cryogenic discharge heat exchanger HX-DC1 to replenish cryogenic energy for the cryogenic tank DCD; among them, the liquefied main gas under the discharge condition of the LAES system exchanges cold energy with the corresponding heat exchange medium in the cryogenic discharge heat exchanger HX-DC1 and the shallow discharge heat exchanger HX-DC2 in turn.

[0106] In some embodiments, the coupling system in the embodiments of the present invention further includes: an air purifier (not shown), a compressor C, a low-temperature expander CE, a liquid-gas separator LAS and a liquid air storage tank LAD arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; wherein, the first shallow cold charging heat exchanger HX-SC1 is arranged in front of the main gas inlet of the compressor C, and the second shallow cold charging heat exchanger HX-SC2 is arranged between the compressor C and the low-temperature expander CE; the deep cold charging heat exchanger HX-CB is arranged between the second shallow cold charging heat exchanger HX-SC2 and the low-temperature expansion machine CE.

[0107] When the LNG-RG system is running and the LAES system is in a charging condition, the shallow cold energy generated by the LNG-RG system and stored by the LAES system can be jointly output to the main gas in the LAES system that has undergone air purification but has not undergone one or more stages of compression, as well as the main gas that has undergone one or more stages of compression but has not absorbed deep cold energy; and, the deep cold energy generated by the LNG-RG system and stored by the LAES system can be jointly output to the main gas in the LAES system that has absorbed shallow cold energy but has not been expanded and liquefied.

[0108] By exporting shallow cooling energy to the main gas that has undergone air purification but has not yet undergone one or more stages of compression, the LNG-RG system's shallow cooling energy can be used to initially cool the main gas before it is compressed by the LAES system. This allows for cryogenic compression of the main gas during the subsequent compression process, reducing the overall power consumption of the compressor unit and the electricity cost of the LAES system under charging conditions. Furthermore, air purification of the main gas before cooling can remove dust, water, and carbon dioxide from the incoming ambient air, preventing condensation and crystallization of water and carbon dioxide after cooling, which can cause pipeline blockage and damage.

[0109] As shown in FIG13 , FIG13 is a third example of a first coupling working condition of the coupling system according to an embodiment of the present invention, which is applicable to a case where multi-stage compression is selected based on the third structural example of the coupling system shown in FIG9 ;

[0110] Preferably, when a compressor unit is used to perform multi-stage compression of the main gas, shallow cooling energy is used to exchange cooling energy after each stage of the compressor. For example, when a three-stage compressor unit is used, it includes a first-stage compressor C1, a second-stage compressor C2, and a third-stage compressor C3 connected in sequence. For each stage of the compressor, a second shallow cooling charging heat exchanger HX-SC2, a third shallow cooling charging heat exchanger HX-SC3, and a fourth shallow cooling charging heat exchanger HX-SC4 are provided after the corresponding stage; wherein the second shallow cooling charging heat exchanger HX-SC2 corresponds to the first-stage compressor C1 and is used to cool the main gas output by the first-stage compressor C1, the third shallow cooling charging heat exchanger HX-SC3 corresponds to the second-stage compressor C2 and is used to cool the main gas output by the second-stage compressor C2, and the fourth shallow cooling charging heat exchanger HX-SC4 corresponds to the first-stage compressor C3 and is used to cool the main gas output by the first-stage compressor C3. In this case, the fourth shallow cooling charging heat exchanger is close to the deep cooling charging heat exchanger.

[0111] As shown in FIG14 , FIG14 is a fourth structural example of a coupling system of an LNG-RG system and a LAES system according to an embodiment of the present invention, which adds an ultra-cold charging heat exchanger HX-UC to the third structural example shown in FIG9 ; FIG15 is a fourth structural example of a first coupling operating condition of the coupling system according to an embodiment of the present invention, which is applicable to the fourth structural example of the coupling system shown in FIG14 ;

[0112] In some embodiments, the LAES system of the present invention further includes: an ultra-cold charging heat exchanger HX-UC connected to both the main gas liquefaction path and the return main gas path; wherein the ultra-cold charging heat exchanger HX-UC is located after the cryogenic charging heat exchanger HX-CB along the main gas liquefaction direction on the main gas liquefaction path, and before the cryogenic charging heat exchanger HX-CB along the return main gas path, for cascade recovery and utilization of the ultra-cold energy and cryogenic energy of the return main gas. In addition, the return main gas path can also pass through the cryogenic charging heat exchanger HX-CB and be redirected back to the main gas liquefaction path.

[0113] As shown in FIG16 , FIG16 is a fourth coupling operating condition example 2 of the coupling system according to an embodiment of the present invention, which is applicable to the structural example 3 of the coupling system shown in FIG9 ;

[0114] In some embodiments, the LAES system in the embodiments of the present invention further includes: a gas phase passage running through the shallow natural gas heat exchanger HX-NG2 and the cryogenic natural gas heat exchanger HX-NG1, which is used to transport purified ambient air through the gas phase passage when the LNG-RG system is running and the LAES system is shut down or there is excess cold energy in the cold storage tank, and to exchange cold energy with the LNG-RG system in the shallow natural gas heat exchanger and the cryogenic natural gas heat exchanger in turn.

[0115] Those skilled in the art should understand that the coupling system in the embodiment of the present invention may include a number of valve bodies to control the switching between various paths, cycles, and loops (between various coupling working conditions) in the coupling system; among them, using valve bodies to control the on-off state of pipelines is a conventional technology in this field. In addition, through the diagrams in the coupling working condition examples in the embodiments of the present invention, the solid line indicates connection (activation) and the dotted line indicates blocking (shutdown), which can also clearly indicate the on-off state under various working conditions. The present invention will not elaborate on this.

[0116] In some embodiments, the LAES system's own cold storage equipment includes a shallow cold tank for storing and releasing shallow cold energy, and a cryogenic tank for storing and releasing deep cold energy. The shallow cold tank's hot-end temperature is between ambient temperature and zero degrees Celsius, but not below zero degrees Celsius, and its cold-end temperature is the shallow cold temperature. The cryogenic tank's hot-end temperature is the shallow cold temperature, and its cold-end temperature is the liquid-to-gas phase transition temperature during LNG regasification. The choice of the shallow cold temperature is determined by the LAES system's operating parameters and the compressor's actual low-temperature operating performance and parameters.

[0117] As shown in FIG17 , FIG17 is a fifth structural example of a coupling system of an LNG-RG system and a LAES system in an embodiment of the present invention.

[0118] In the LAES system of the present invention, the shallow cold storage tank (SCD) and deep cold storage tank (DCD) can be configured as one or more series / parallel tank structures (not shown). The specific design can be based on the cold storage and release requirements of the cold storage tanks in the LAES system. In some embodiments, the number of shallow cold storage tanks (SCD) and deep cold storage tanks (DCD) in the LAES system can be configured based on the cold release requirements. Multiple shallow cold storage tanks and deep cold storage tanks can be configured to meet the flexible coupling requirements of LNG-RG and LAES operating modes. In this embodiment, the SCD and DCD are solid packed beds, using a fluid heat exchange medium for cold energy exchange.

[0119] In some embodiments, each independent shallow cold tank (SCD) and deep cold tank (DCD) can be paired. For example, the first shallow cold tank (SCD1) and the second shallow cold tank (SCD2) can replace the shallow cold tank (SCD), while the first deep cold tank (DCD1) and the second deep cold tank (DCD2) can replace the deep cold tank (DCD). Both shallow cold tanks (SCD1 and SCD2) contain only one portion of the second shallow cold heat exchange medium. Before charging, shallow cold tank (SCD1) contains the cooler second shallow cold heat exchange medium, while shallow cold tank (SCD2) is empty. During charging, the second shallow cold heat exchange medium in shallow cold tank (SCD1) continuously flows into shallow cold tank (SCD2), releasing cold energy to cool the main gas. After charging is complete, shallow cold tank (SCD1) is empty, while shallow cold tank (SCD2) is full. During static and discharge periods, the warmer second shallow cold heat exchange medium in shallow cold tank (SCD2) continuously flows into SCD1, absorbing the cold energy output by the LNG-RG system and the cold energy generated by the LAES discharge.

[0120] The LNG-RG system in the embodiment of the present invention uses the natural gas on the liquefied natural gas regasification path as a cold energy carrier to directly exchange cold energy in the LAES system; or uses other heat exchange media as a cold energy carrier to indirectly exchange cold energy with the LAES system. Among them, using the natural gas on the liquefied natural gas regasification path as a cold energy carrier to exchange cold energy with the main gas means that the natural gas and the main gas are exchanged cold energy in the same heat exchanger, while using other heat exchange media as a cold energy carrier to exchange cold energy with the main gas means that an additional heat exchange medium is added between the natural gas and the main gas, and the cold energy of the natural gas is transferred to the main gas for liquefaction through the heat exchange medium, and the heat energy of the main gas is transferred to the natural gas for regasification.

[0121] Preferably, the LNG-RG system and the LAES system in the embodiment of the present invention can use other heat exchange media as cold energy carriers to exchange cold energy with the main gas, which can avoid placing high-pressure natural gas and high-pressure air in the same equipment.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coupling system of LNG-RG and LAES, characterized in that: Including LNG-RG system and LAES system; The LNG-RG system includes: a natural gas heat exchanger connected to the liquefied natural gas regasification path; the LAES system includes: a cold storage tank, a charging heat exchanger connected to the main gas liquefaction path, and a discharging heat exchanger connected to the liquefied main gas regasification path; A first heat exchange cycle using a first heat exchange medium for cold energy exchange is formed between the natural gas heat exchanger and the charging heat exchanger; a second heat exchange cycle using a second heat exchange medium for cold energy exchange is formed between the charging heat exchanger, the cold storage tank, and the discharging heat exchanger; Among them, in the first heat exchange cycle, the hot ends and cold ends of the natural gas heat exchanger and the charging heat exchanger are connected respectively; in the second heat exchange cycle, the hot ends and cold ends of the charging heat exchanger, the cold storage tank and the discharge heat exchanger are connected respectively.

2. The coupling system according to claim 1, characterized in that When the LNG-RG system is running and the LAES system is in charging condition, static condition, discharging condition or condition change, the first heat exchange medium in the first heat exchange cycle maintains a flow cycle of the cold end of the natural gas heat exchanger, the cold end of the charging heat exchanger, the hot end of the charging heat exchanger, and the hot end of the natural gas heat exchanger; the second heat exchange medium in the second heat exchange cycle exchanges cold energy with the first heat exchange medium in the charging heat exchanger.

3. The coupling system according to claim 1, characterized in that When the LNG-RG system is shut down and the LAES system is in the charging state, the second heat exchange medium in the second heat exchange cycle circulates in the direction of the cold end of the cold storage tank, the cold end of the charging heat exchanger, the hot end of the charging heat exchanger, and the hot end of the cold storage tank; the main gas under the charging state of the LAES system exchanges cold energy with the second heat exchange medium in the charging heat exchanger; When the LNG-RG system is shut down and the LAES system is in the discharge condition, the second heat exchange medium in the second heat exchange cycle circulates in the flow direction of the cold end of the discharge heat exchanger, the cold end of the cold storage tank, the hot end of the cold storage tank, and the hot end of the discharge heat exchanger; the liquefied main gas under the discharge condition of the LAES system exchanges cold energy with the second heat exchange medium in the discharge heat exchanger.

4. The coupling system according to claim 1, characterized in that The cold storage tank includes: a shallow cold tank for storing and releasing shallow cold energy, and a cryogenic tank for storing and releasing deep cold energy; the natural gas heat exchanger includes: a cryogenic natural gas heat exchanger and a shallow cold natural gas heat exchanger arranged in sequence along the liquefied natural gas regasification direction on the liquefied natural gas regasification path; the charging heat exchanger includes: a shallow cold charging heat exchanger and a cryogenic charging heat exchanger arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; the discharging heat exchanger includes: a cryogenic discharge heat exchanger and a shallow cold discharge heat exchanger arranged in sequence along the liquefied main gas regasification direction on the liquefied main gas regasification path; the first heat exchange medium includes: a first shallow cold heat exchange medium and a first cryogenic heat exchange medium; the second heat exchange medium includes: a second shallow cold heat exchange medium and a second cryogenic heat exchange medium; The first heat exchange cycle includes: a first shallow cold closed loop for exchanging cold energy between the shallow cold natural gas heat exchanger and the shallow cold charging heat exchanger using a first shallow cold heat exchange medium; and a first cryogenic closed loop for exchanging cold energy between the deep cold natural gas heat exchanger and the deep cold charging heat exchanger using the first cryogenic heat exchange medium. The shallow-cooled natural gas heat exchanger and the shallow-cooled charging heat exchanger in the first shallow-cooled closed circuit are connected at their hot ends and cold ends, respectively; the deep-cooled natural gas heat exchanger and the deep-cooled charging heat exchanger in the first deep-cooled closed circuit are connected at their hot ends and cold ends, respectively; The second heat exchange cycle includes: a second shallow cooling closed loop for exchanging cold energy between the shallow cooling charging heat exchanger, the shallow cooling tank, and the shallow cooling discharge heat exchanger using a second shallow cooling heat exchange medium; and a second deep cooling closed loop for exchanging cold energy between the deep cooling charging heat exchanger, the deep cooling tank, and the deep cooling discharge heat exchanger using a second deep cooling heat exchange medium. Among them, the hot ends and cold ends of the shallow cooling charging heat exchanger, the shallow cooling tank, and the shallow cooling discharge heat exchanger in the second shallow cooling closed loop are respectively connected; the hot ends and cold ends of the deep cooling charging heat exchanger, the deep cooling tank, and the deep cooling discharge heat exchanger in the second deep cooling closed loop are respectively connected.

5. The coupling system according to claim 4, characterized in that The shallow cooling charging heat exchanger includes: a first shallow cooling charging heat exchanger and a second shallow cooling charging heat exchanger arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; The shallow-cooled natural gas heat exchanger and the first shallow-cooled charging heat exchanger form the first shallow-cooled closed circuit for exchanging cold energy with the first shallow-cooled heat exchange medium; the first shallow-cooled charging heat exchanger, the second shallow-cooled charging heat exchanger, the shallow-cooled tank, and the shallow-cooled discharge heat exchanger form the second shallow-cooled closed circuit for exchanging cold energy with the second shallow-cooled heat exchange medium. Among them, the hot ends and cold ends of the shallow-cooled natural gas heat exchanger and the first shallow-cooled charging heat exchanger in the first shallow-cooled closed loop are connected respectively; the hot ends and cold ends of the first shallow-cooled charging heat exchanger, the second shallow-cooled charging heat exchanger, the shallow-cooled tank and the shallow-cooled discharge heat exchanger in the second shallow-cooled closed loop are connected respectively.

6. The coupling system according to claim 5, characterized in that When the LNG-RG system is running and the LAES system is in charging condition, static condition, discharging condition or condition change, the first cryogenic heat exchange medium in the first cryogenic closed loop maintains a flow circulation of the cryogenic natural gas heat exchanger cold end, the cryogenic charging heat exchanger cold end, the cryogenic charging heat exchanger hot end, and the cryogenic natural gas heat exchanger hot end; at the same time, the first shallow cooling heat exchange medium in the first shallow cooling closed loop maintains a flow circulation of the shallow cooling natural gas heat exchanger cold end, the first shallow cooling charging heat exchanger cold end, the first shallow cooling charging heat exchanger hot end, and the shallow cooling natural gas heat exchanger hot end.

7. The coupling system according to claim 5, characterized in that When the LNG-RG system is running and the LAES system is in the charging condition, the second shallow cold heat exchange medium in the second shallow cold closed loop circulates in the flow direction of the first shallow cold charging heat exchanger hot end, the shallow cold tank hot end, the shallow cold tank cold end, and the first shallow cold charging heat exchanger cold end; and circulates in the flow direction of the shallow cold tank cold end, the second shallow cold charging heat exchanger cold end, the second shallow cold charging heat exchanger hot end, and the cold end of the cold storage tank; at the same time, the second deep cold heat exchange medium in the second deep cold closed loop circulates in the flow direction of the deep cold charging heat exchanger hot end, the deep cold tank hot end, the deep cold tank cold end, and the deep cold charging heat exchanger cold end; The main gas under the charging condition of the LAES system exchanges cold energy with the corresponding heat exchange medium in the first shallow cooling charging heat exchanger, the second shallow cooling charging heat exchanger, and the deep cooling charging heat exchanger in turn.

8. The coupling system according to claim 5, characterized in that When the LNG-RG system is running and the LAES system is in a static condition, the second shallow cooling heat exchange medium in the second shallow cooling closed loop circulates in the flow direction of the first shallow cooling charging heat exchanger cold end, the shallow cooling tank cold end, the shallow cooling tank hot end, and the first shallow cooling charging heat exchanger hot end to replenish shallow cooling energy for the shallow cooling tank; at the same time, the second deep cooling heat exchange medium in the second deep cooling closed loop circulates in the flow direction of the deep cooling charging heat exchanger cold end, the deep cooling tank cold end, the deep cooling tank hot end, and the deep cooling charger hot end to replenish deep cooling energy for the deep cooling tank.

9. The coupling system according to claim 5, characterized in that When the LNG-RG system is running and the LAES system is in the discharging condition, the second shallow cold heat exchange medium in the second shallow cold closed loop circulates in the flow direction of the first shallow cold charging heat exchanger cold end, the shallow cold tank cold end, the shallow cold tank hot end, and the first shallow cold charging heat exchanger hot end; and, circulates in the flow direction of the shallow cold discharge heat exchanger cold end, the shallow cold tank cold end, the shallow cold tank hot end, and the shallow cold discharge heat exchanger hot end to replenish shallow cold energy for the shallow cold tank; at the same time, the second deep cold heat exchange medium in the second deep cold closed loop circulates in the flow direction of the deep cold charging heat exchanger cold end, the deep cold tank cold end, the deep cold tank hot end, and the deep cold charging heat exchanger hot end; and, circulates in the flow direction of the deep cold discharge heat exchanger cold end, the deep cold tank cold end, the deep cold tank hot end, and the deep cold discharge heat exchanger hot end to replenish deep cold energy for the deep cold tank; The liquefied main gas under the LAES system discharge condition exchanges cold energy with the corresponding heat exchange medium in the deep-cold discharge heat exchanger and the shallow-cold discharge heat exchanger in turn.

10. The coupling system according to claim 5, characterized in that The LAES system also includes: a compressor, a low-temperature expander, a liquid-gas separator and a liquid air storage tank arranged in sequence along the main gas liquefaction direction on the main gas liquefaction path; wherein, the first shallow cold charging heat exchanger is arranged in front of the main gas inlet of the compressor, and the second shallow cold charging heat exchanger is arranged between the compressor and the low-temperature expander; the deep cold charging heat exchanger is arranged between the second shallow cold charging heat exchanger and the low-temperature expander.

11. The coupling system according to claim 4, characterized in that The LAES system further includes: The super-cold charging heat exchanger is connected to the main gas liquefaction path and the return main gas path at the same time; wherein, the super-cold charging heat exchanger is located after the deep-cold charging heat exchanger along the main gas liquefaction direction on the main gas liquefaction path, and is located before the deep-cold charging heat exchanger along the return main gas direction on the return main gas path, for cascade recovery and use of the super-cold energy and deep-cold energy of the return main gas.

12. The coupling system according to claim 4, characterized in that Also includes: The gas phase passage running through the shallow natural gas heat exchanger and the cryogenic natural gas heat exchanger is used to transport purified ambient air through the gas phase passage and exchange cold energy with the LNG-RG system in the shallow natural gas heat exchanger and the cryogenic natural gas heat exchanger in sequence when the LNG-RG system is operating and the LAES system is shut down or the cold storage tank has excess cold energy.

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