Natural gas liquefaction device and natural gas liquefaction method suitable for wide environment temperature zone

Abstract

The invention relates to the technical field of natural gas liquefaction equipment, and discloses a natural gas liquefaction device and a natural gas liquefaction method suitable for a wide environment temperature zone. An inlet of a pre-cooling mixed refrigeration system of the device is used for allowing natural gas to be liquefied to enter. An inlet of the cryogenic mixed refrigeration system is communicated with a natural gas outlet of the precooling mixed refrigeration system, and a natural gas outlet of the cryogenic mixed refrigeration system is used for discharging liquefied natural gas; and the natural gas entering the cryogenic mixed refrigeration system exchanges heat with the cryogenic mixed refrigerant. The refrigerant blending system is connected with the pre-cooling mixed refrigeration system and the cryogenic mixed refrigeration system and used for increasing the content of heavy components in the pre-cooling mixed refrigerant and the cryogenic mixed refrigerant when the environment temperature rises and reducing the content of the heavy components in the pre-cooling mixed refrigerant and the cryogenic mixed refrigerant when the environment temperature drops. And by introducing the refrigerant blending system, the problems of operation adaptability and energy efficiency balance caused by seasonal temperature difference of the liquefying device in the extremely cold region are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas liquefaction equipment, and particularly relates to a natural gas liquefaction device suitable for a wide ambient temperature range and a natural gas liquefaction method. BACKGROUND

[0002] In recent years, the production and trade of liquefied natural gas (LNG) are increasingly active in the world. As a clean and efficient strategic energy, LNG is gradually becoming a new focus of the development of the world oil and gas industry. Reasonable design of a natural gas liquefaction plant is of great significance for China to ensure stable energy supply, maintain energy security, promote energy structure diversification and protect the environment.

[0003] With the continuous development of large natural gas fields in China and the introduction of Russian pipeline natural gas, especially the gradual development and utilization of large natural gas fields around the Arctic in recent years, the demand for construction of natural gas liquefaction devices in extremely cold regions is increasingly urgent. The most notable feature of extremely cold regions is that the temperature difference between winter and summer is extremely large: the winter is long and cold, and the minimum temperature can be lower than -50 DEG C; the summer is short, but the maximum temperature can still be close to 30 DEG C. Under this environment, how to efficiently utilize the winter air cold source of the liquefaction device and realize stable and efficient operation under different seasonal conditions in winter and summer has become a key technical problem to be solved at present. SUMMARY

[0004] The present application provides a natural gas liquefaction device suitable for a wide ambient temperature range and a natural gas liquefaction method, which are used to solve at least one problem in the background.

[0005] The present application provides a natural gas liquefaction device suitable for a wide ambient temperature range, comprising: a precooling mixed refrigeration system, a natural gas inlet of the precooling mixed refrigeration system being used for entering natural gas to be liquefied, and the natural gas entering the precooling mixed refrigeration system being exchanged with a precooling mixed refrigerant; a deep cooling mixed refrigeration system, a natural gas inlet of the deep cooling mixed refrigeration system being communicated with a natural gas outlet of the precooling mixed refrigeration system, and a natural gas outlet of the deep cooling mixed refrigeration system being used for discharging liquefied natural gas; the natural gas entering the deep cooling mixed refrigeration system being exchanged with a deep cooling mixed refrigerant; a refrigerant matching system, connected with the precooling mixed refrigeration system and the deep cooling mixed refrigeration system, used for increasing the content of heavy components in the precooling mixed refrigerant and the deep cooling mixed refrigerant when the ambient temperature rises, and used for reducing the content of heavy components in the precooling mixed refrigerant and the deep cooling mixed refrigerant when the ambient temperature decreases.

[0006] According to the natural gas liquefaction device suitable for a wide ambient temperature range provided by the present application, the refrigerant matching system comprises: A pre-cooling refrigerant mixing module is connected to the pre-cooling mixed refrigeration system and is used to increase the content of heavy components in the pre-cooling mixed refrigerant when the ambient temperature rises, and also to decrease the content of heavy components in the pre-cooling mixed refrigerant when the ambient temperature falls. A cryogenic refrigerant blending module is connected to the cryogenic hybrid refrigeration system. It is used to increase the content of heavy components in the cryogenic hybrid refrigerant when the ambient temperature rises, and to decrease the content of heavy components in the cryogenic hybrid refrigerant when the ambient temperature falls.

[0007] According to the natural gas liquefaction apparatus for a wide ambient temperature range provided by the present invention, the pre-cooling hybrid refrigeration system includes: A precooling heat exchange module includes a precooling heat exchanger, a first precooling throttling valve, and a second precooling throttling valve. A precooling heat exchange chamber is formed within the precooling heat exchanger, and a first precooling heat exchange tube, a third precooling heat exchange tube, and a fourth precooling heat exchange tube are disposed within the precooling heat exchange chamber. The natural gas inlet of the first precooling heat exchange tube is used to supply natural gas to be liquefied. The outlet end of the third precooling heat exchange tube is connected to the upper half of the precooling heat exchange chamber through the first precooling throttling valve, and the outlet end of the fourth precooling heat exchange tube is connected to the lower half of the precooling heat exchange chamber through the second precooling throttling valve. The precooling module has its inlet end connected to the precooling heat exchange chamber, and is used to process the precooled mixed refrigerant discharged from the precooling heat exchange chamber, and to discharge precooled gaseous refrigerant and precooled liquid refrigerant; the gaseous outlet of the precooling module is connected to the inlet end of the third precooling heat exchange tube, and the liquid outlet of the precooling module is connected to the inlet end of the fourth precooling heat exchange tube. The precooling refrigerant preparation module is used to store the heavy components in the precooling mixed refrigerant. The outlet end of the precooling refrigerant preparation module is connected to the inlet end of the precooling module, and the outlet end of the precooling refrigerant preparation module is connected to the liquid phase outlet of the precooling module.

[0008] According to the natural gas liquefaction apparatus for a wide ambient temperature range provided by the present invention, the precooling module includes: A first precooling compressor, the inlet of which is connected to the precooling heat exchange chamber; The first precooling cooler and the first precooling gas-liquid separator are connected. The outlet of the first precooling compressor is connected to the inlet of the first precooling gas-liquid separator through the first precooling cooler. The gas phase outlet of the first precooling gas-liquid separator is connected to the inlet end of the third precooling heat exchange tube, and the liquid phase outlet of the first precooling gas-liquid separator is connected to the inlet end of the fourth precooling heat exchange tube. The outlet of the precooling refrigerant mixing module is connected to the inlet of the first precooling compressor, and the inlet of the precooling refrigerant mixing module is connected to the liquid phase outlet of the first precooling gas-liquid separator.

[0009] According to the natural gas liquefaction apparatus for a wide ambient temperature range provided by the present invention, the precooling module further includes: The second precooling compressor is connected to the inlet of the first precooling gas-liquid separator. The second precooling cooler and the second precooling gas-liquid separator are connected. The outlet of the second precooling compressor is connected to the inlet of the second precooling gas-liquid separator through the second precooling cooler. The gas phase outlet of the second precooling gas-liquid separator is connected to the inlet of the third precooling heat exchange tube. The liquid phase outlet of the second precooling gas-liquid separator is connected to the inlet of the fourth precooling heat exchange tube. The liquid phase outlet of the second precooling gas-liquid separator is also connected to the inlet of the precooling refrigerant mixing module.

[0010] According to the natural gas liquefaction apparatus for a wide ambient temperature range provided by the present invention, the pre-cooling refrigerant preparation module includes: A first precooling refrigerant mixing tank and a second precooling refrigerant mixing tank, wherein the outlets of the first and second precooling refrigerant mixing tanks are both connected to the inlet of the first precooling compressor; the inlet of the first precooling refrigerant mixing tank is connected to the liquid phase outlet of the second precooling gas-liquid separator and the outlet of the second precooling compressor; the inlet of the second precooling refrigerant mixing tank is connected to the liquid phase outlet of the first precooling gas-liquid separator and the outlet of the second precooling compressor.

[0011] According to the natural gas liquefaction apparatus for a wide ambient temperature range provided by the present invention, a second precooling heat exchange tube is further provided in the precooling heat exchange chamber; the cryogenic hybrid refrigeration system includes: A cryogenic heat exchange module includes a cryogenic heat exchanger, a first cryogenic throttling valve, and a second cryogenic throttling valve. A cryogenic heat exchange chamber is formed within the cryogenic heat exchanger, and a first cryogenic heat exchange tube, a second cryogenic heat exchange tube, and a third cryogenic heat exchange tube are installed within the cryogenic heat exchange chamber. The inlet end of the first cryogenic heat exchange tube is connected to the outlet end of the first pre-cooling heat exchange tube, and the natural gas outlet of the cryogenic heat exchanger tube is used to discharge liquefied natural gas. The outlet end of the second cryogenic heat exchange tube is connected to the upper half of the cryogenic heat exchange chamber through the first cryogenic throttling valve; the outlet end of the third cryogenic heat exchange tube is connected to the lower half of the cryogenic heat exchange chamber through the second cryogenic throttling valve. The cryogenic module includes a first cryogenic compressor, a first cryogenic cooler, and a first cryogenic gas-liquid separator. The inlet of the first cryogenic compressor is connected to the cryogenic heat exchange chamber, and the outlet of the first cryogenic compressor is connected to the inlet of a second pre-cooling heat exchange tube via the first cryogenic cooler. The outlet of the second pre-cooling heat exchange tube is connected to the inlet of the first cryogenic gas-liquid separator. The gas phase outlet of the first cryogenic gas-liquid separator is connected to the inlet of the second cryogenic heat exchange tube, and the liquid phase outlet of the first cryogenic gas-liquid separator is connected to the inlet of the third cryogenic heat exchange tube. The cryogenic refrigerant blending module is used to store the heavy components in the cryogenic mixed refrigerant. The inlet of the cryogenic refrigerant blending module is connected to the liquid phase outlet of the first cryogenic gas-liquid separator, and the outlet of the cryogenic refrigerant blending module is connected to the inlet of the first cryogenic compressor.

[0012] According to the natural gas liquefaction apparatus for a wide ambient temperature range provided by the present invention, the cryogenic module further includes: The second cryogenic compressor and the second cryogenic cooler are connected in sequence, with the outlet of the first cryogenic cooler connected to the inlet of the second precooling heat exchange tube via the second cryogenic compressor and the second cryogenic cooler.

[0013] According to the natural gas liquefaction device suitable for a wide ambient temperature range provided by the present invention, the precooling mixed refrigerant includes at least two of methane, ethane, ethylene, propane, and butane; the cryogenic mixed refrigerant includes at least two of nitrogen, methane, ethane, ethylene, and propane.

[0014] A second aspect of the present invention provides a natural gas liquefaction method for use in the natural gas liquefaction apparatus described in any one of the preceding claims, applicable to a wide ambient temperature range, the natural gas liquefaction method comprising: Get the current ambient temperature; When the current ambient temperature is higher than the previously obtained ambient temperature, add heavy components of precooling mixed refrigerant to the precooling mixed refrigeration system and heavy components of cryogenic mixed refrigerant to the cryogenic mixed refrigeration system. When the current ambient temperature is lower than the previously obtained ambient temperature, recover the heavy components of the precooled mixed refrigerant and the heavy components of the cryogenic mixed refrigerant.

[0015] The natural gas liquefaction unit provided by this invention, applicable to a wide range of ambient temperatures, can reduce the content of heavy components in the pre-cooling and cryogenic refrigerant mixture during winter when ambient temperatures are extremely low (e.g., -50°C). With reduced heavy components, the refrigerant's evaporation temperature decreases, making it easier to utilize low-temperature ambient air for cooling, significantly reducing compressor power consumption and achieving energy-saving operation. When ambient temperatures rise in summer (e.g., approaching 30°C), the refrigerant mixture system increases the proportion of heavy components in the pre-cooling and cryogenic refrigerants. Increasing the heavy component content allows the refrigerant to condense effectively at higher temperatures, maintaining sufficient cooling capacity and preventing a decrease in system cooling efficiency or operational instability due to rising ambient temperatures. This natural gas liquefaction unit, applicable to a wide range of ambient temperatures, can maintain high heat exchange efficiency in low-temperature environments by optimizing the refrigerant composition, avoiding efficiency losses caused by mismatch between refrigerant properties and ambient temperature. By flexibly adjusting the refrigerant composition, it ensures that the mixed refrigerant maintains suitable phase change characteristics and heat exchange performance at different ambient temperatures, thereby maintaining the continuity and stability of the liquefaction process.

[0016] Traditional fixed-component refrigerant systems struggle to maintain performance in both winter and summer under extreme temperature variations. This device, however, utilizes a refrigerant blending system to achieve real-time, on-demand adjustment of the refrigerant composition, enabling the system to automatically adapt to external temperature changes without requiring shutdowns or significant adjustments to operating parameters. The pre-cooling and cryogenic stages work in tandem, combined with the refrigerant blending function, maintaining high liquefaction efficiency and equipment reliability across a wide temperature range (-50℃ to 30℃), making it particularly suitable for extremely cold regions with long winters and short summers.

[0017] This invention introduces a refrigerant blending system to achieve dynamic optimization of the pre-cooling and cryogenic refrigerant mixture, enabling the liquefaction unit to fully utilize the low-temperature cold source in winter while adapting to high-temperature conditions in summer. This allows it to maintain efficient, stable, and energy-saving operation even in extremely cold regions with extreme annual temperature variations. This design effectively solves the operational adaptability and energy efficiency balance problems of liquefaction units in extremely cold regions caused by seasonal temperature differences. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is one of the structural schematic diagrams of a natural gas liquefaction device suitable for a wide range of ambient temperatures provided by the present invention.

[0020] Figure 2This is the second structural schematic diagram of the natural gas liquefaction device suitable for a wide range of ambient temperatures provided by the present invention.

[0021] Figure 3 This is the third schematic diagram of the structure of the natural gas liquefaction device suitable for a wide range of ambient temperatures provided by the present invention.

[0022] Figure 4 This is a schematic diagram of the natural gas liquefaction method provided by the present invention.

[0023] Figure label: 100. Pre-cooling hybrid refrigeration system; 110. Pre-cooling heat exchange module; 120. Pre-cooling module; 101. First pre-cooling heat exchange tube; 102. Second pre-cooling heat exchange tube; 103. Third pre-cooling heat exchange tube; 104. Fourth pre-cooling heat exchange tube; 105. Pre-cooling heat exchange chamber; 111. Pre-cooling heat exchanger; 112. First pre-cooling throttling valve; 113. Second pre-cooling throttling valve; 121. First pre-cooling compressor; 122. First pre-cooling cooler; 123. First pre-cooling gas-liquid separator; 124. Second pre-cooling compressor; 125. Second pre-cooling cooler; 126. Second pre-cooling gas-liquid separator; 200. Cryogenic hybrid refrigeration system; 210. Cryogenic heat exchange module; 220. Cryogenic module; 201. First cryogenic heat exchange tube; 202. Second cryogenic heat exchange tube; 203. Third cryogenic heat exchange tube; 204. Cryogenic heat exchange chamber; 211. Cryogenic heat exchanger; 212. First cryogenic throttling valve; 213. Second cryogenic throttling valve; 221. First cryogenic compressor; 222. First cryogenic cooler; 223. First cryogenic gas-liquid separator; 224. Second cryogenic compressor; 225. Second cryogenic cooler; 300. Refrigerant mixing system; 310. Pre-cooled refrigerant mixing module; 320. Cryogenic refrigerant mixing module; 311. First pre-cooled refrigerant mixing tank; 312. Second pre-cooled refrigerant mixing tank; 400. First air cooler; 501, First regulating valve; 502, Second regulating valve; 503, Third regulating valve; 504, Fourth regulating valve; 505, Fifth regulating valve; 506, Sixth regulating valve; 507, Seventh regulating valve; 508, Eighth regulating valve; 509, Ninth regulating valve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] The following is combined with Figures 1 to 4 The present invention describes a natural gas liquefaction apparatus and a natural gas liquefaction method applicable to a wide range of ambient temperatures.

[0026] like Figure 1 As shown, a specific embodiment of the first aspect of the present invention provides a natural gas liquefaction device suitable for a wide ambient temperature range. This natural gas liquefaction device includes a pre-cooling hybrid refrigeration system 100, a cryogenic hybrid refrigeration system 200, and a refrigerant blending system 300.

[0027] The pre-cooling mixing refrigeration system 100 has a natural gas inlet for receiving natural gas to be liquefied, which exchanges heat with the pre-cooling mixing refrigerant. The cryogenic mixing refrigeration system 200 has a natural gas inlet connected to the natural gas outlet of the pre-cooling mixing refrigeration system 100, which discharges the liquefied natural gas; the natural gas entering the cryogenic mixing refrigeration system 200 exchanges heat with the cryogenic mixing refrigerant. A refrigerant blending system 300 is connected to both the pre-cooling mixing refrigeration system 100 and the cryogenic mixing refrigeration system 200, used to increase the content of heavy components in the pre-cooling mixing refrigerant and the cryogenic mixing refrigerant when the ambient temperature rises, and also to decrease the content of heavy components in the pre-cooling mixing refrigerant and the cryogenic mixing refrigerant when the ambient temperature decreases.

[0028] In this embodiment, during winter when the ambient temperature is extremely low (e.g., -50°C), the refrigerant blending system 300 can reduce the content of heavy components in the pre-cooling and cryogenic refrigerant mixture. With fewer heavy components, the refrigerant's evaporation temperature decreases, making it easier to utilize low-temperature ambient air for cooling, significantly reducing compressor power consumption and achieving energy-saving operation. When the ambient temperature rises in summer (e.g., approaching 30°C), the refrigerant blending system 300 increases the proportion of heavy components in the pre-cooling and cryogenic refrigerants. Increasing the content of heavy components allows the refrigerant to condense effectively at higher temperatures, maintaining sufficient cooling capacity and preventing a decrease in system cooling efficiency or operational instability due to rising ambient temperatures. The natural gas liquefaction device of this invention, applicable to a wide ambient temperature range, can maintain high heat exchange efficiency in low-temperature environments by optimizing the refrigerant composition, avoiding efficiency losses caused by mismatch between refrigerant properties and ambient temperature. By flexibly adjusting the refrigerant composition, it can be ensured that the mixed refrigerant maintains suitable phase change characteristics and heat exchange performance at different ambient temperatures, thereby maintaining the continuity and stability of the liquefaction process.

[0029] Traditional fixed-component refrigerant systems struggle to maintain performance in both winter and summer under extreme temperature variations. This device, however, utilizes a refrigerant blending system 300 to achieve real-time, on-demand adjustment of the refrigerant components, enabling the system to automatically adapt to external temperature changes without requiring shutdown or significant adjustments to operating parameters. The pre-cooling and cryogenic stages work in tandem, combined with the refrigerant blending function, maintaining high liquefaction efficiency and equipment reliability across a wide temperature range (-50℃ to 30℃), making it particularly suitable for extremely cold regions with long winters and short summers.

[0030] The embodiments of this invention, by introducing a refrigerant blending system 300, achieve dynamic optimization of the pre-cooled and cryogenic mixed refrigerant components. This enables the liquefaction unit to fully utilize the low-temperature cold source in winter while adapting to high-temperature conditions in summer, thus maintaining efficient, stable, and energy-saving operation even in extremely cold regions with extreme annual temperature differences. This design effectively solves the problem of operational adaptability and energy efficiency balance in liquefaction units in extremely cold regions caused by seasonal temperature differences.

[0031] It should be noted that the pre-cooled mixed refrigerant includes at least two refrigerants, of which the one with a relatively higher density is the heavy component and the one with a relatively lower density is the light component.

[0032] It should be noted that cryogenic mixed refrigerants include at least two refrigerants, of which the one with a relatively higher density is the heavy component and the one with a relatively lower density is the light component.

[0033] In some embodiments, the precooling mixed refrigerant includes at least two of methane, ethane, ethylene, propane, and butane.

[0034] Optionally, the pre-cooled mixed refrigerant includes at least three of the following: methane, ethane, ethylene, propane, and butane.

[0035] Preferably, the pre-cooling mixed refrigerant includes methane, ethane, propane, and butane. The rearranged refrigerant is butane.

[0036] In some embodiments, the cryogenic mixed refrigerant includes at least two of nitrogen, methane, ethane, ethylene, and propane.

[0037] Optionally, the cryogenic mixed refrigerant includes at least three of the following: nitrogen, methane, ethane, ethylene, and propane.

[0038] Preferably, the cryogenic mixed refrigerant includes nitrogen, methane, ethane and propane, wherein the regrouping is propane.

[0039] like Figure 2 As shown, in some embodiments of the present invention, the refrigerant mixing system 300 includes a pre-cooled refrigerant mixing module 310 and a cryogenic refrigerant mixing module 320.

[0040] The pre-cooling refrigerant mixing module 310 is connected to the pre-cooling mixed refrigeration system 100. It is used to increase the content of heavy components in the pre-cooling mixed refrigerant when the ambient temperature rises, and to decrease the content of heavy components in the pre-cooling mixed refrigerant when the ambient temperature falls. The cryogenic refrigerant mixing module 320 is connected to the cryogenic mixed refrigeration system 200. It is used to increase the content of heavy components in the cryogenic mixed refrigerant when the ambient temperature rises, and to decrease the content of heavy components in the cryogenic mixed refrigerant when the ambient temperature falls.

[0041] In this embodiment, the refrigerant properties and temperature ranges required for the pre-cooling and cryogenic stages may differ. By independently configuring the refrigerant mixing module, the proportion of heavy components in the refrigerant can be adjusted according to the heat exchange characteristics and temperature requirements of each stage, avoiding a "one-size-fits-all" mixing approach. This achieves cascaded optimization across the entire process, significantly improving the overall energy efficiency of the system under different ambient temperatures. The dual refrigerant mixing module design allows the pre-cooling and cryogenic cycles to respond independently to changes in ambient temperature. During winter-summer transitions or rapid temperature fluctuations, each stage can adjust its refrigerant composition in a timely manner to avoid mutual interference and maintain stable system pressure and temperature. This enhances the robustness of the device in the face of extreme temperature changes and reduces operational risks caused by mismatches between refrigerant properties and operating conditions. This design enables the device to automatically maintain efficient operation within a wide ambient temperature range of -50℃ to 30℃, making it particularly suitable for extremely cold regions with long winters and short summers. This embodiment achieves precise control and efficient energy management of each temperature stage of the liquefaction process by configuring independent refrigerant mixing modules for the pre-cooling and cryogenic systems. This not only improves the adaptability and operating efficiency of the unit under extreme temperature conditions, but also enhances the flexibility and reliability of the system, providing key technical support for the stable and efficient operation of natural gas liquefaction units suitable for a wide range of ambient temperatures in extremely cold regions throughout the year.

[0042] Optionally, when the ambient temperature rises, the pre-cooling refrigerant mixing module 310 adds heavy components of the pre-cooling mixed refrigerant to the pre-cooling mixed refrigeration system 100, and the cryogenic refrigerant mixing module 320 adds heavy components of the cryogenic mixed refrigerant to the cryogenic mixed refrigeration system 200. When the ambient temperature drops, the pre-cooling refrigerant mixing module 310 recovers heavy components from the pre-cooling mixed refrigerant, and the cryogenic refrigerant mixing module 320 recovers heavy components from the cryogenic mixed refrigerant.

[0043] like Figure 3 As shown, in some embodiments of the present invention, the precooling hybrid refrigeration system 100 includes a precooling heat exchange module 110 and a precooling module 120.

[0044] The precooling heat exchange module 110 includes a precooling heat exchanger 111, a first precooling throttling valve 112, and a second precooling throttling valve 113. A precooling heat exchange chamber 105 is formed within the precooling heat exchanger 111, and a first precooling heat exchange tube 101, a second precooling heat exchange tube 102, a third precooling heat exchange tube 103, and a fourth precooling heat exchange tube 104 are installed within the precooling heat exchange tube 105. The natural gas inlet of the first precooling heat exchange tube 101 is used to supply the natural gas to be liquefied. The outlet of the third precooling heat exchange tube 103 is connected to the upper half of the precooling heat exchange chamber 105 through the first precooling throttling valve 112, and the outlet of the fourth precooling heat exchange tube 104 is connected to the lower half of the precooling heat exchange chamber 105 through the second precooling throttling valve 113. The inlet of the precooling module 120 is connected to the precooling heat exchange chamber 105, and is used to process the precooled mixed refrigerant discharged from the precooling heat exchange chamber 105, and to discharge precooled gaseous refrigerant and precooled liquid refrigerant. The gaseous outlet of the precooling module 120 is connected to the inlet end of the third precooling heat exchange tube 103, and the liquid outlet of the precooling module 120 is connected to the inlet end of the fourth precooling heat exchange tube. The precooling refrigerant preparation module 310 is used to store the heavy components in the precooled mixed refrigerant. The outlet end of the precooling refrigerant preparation module 310 is connected to the inlet end of the precooling module 120, and the outlet end of the precooling refrigerant preparation module 310 is connected to the liquid outlet of the precooling module 120.

[0045] In this embodiment, the precooling heat exchanger 111 is equipped with multiple sets of heat exchange tubes (first to fourth precooling heat exchange tubes 104), and the refrigerant is injected into the upper and lower halves of the precooling heat exchange chamber 105 after being throttled by the first precooling throttling valve 112 and the second precooling throttling valve 113, respectively, achieving segmented cooling and refined temperature management. This structure can more accurately control the cooling curve of natural gas, avoid sudden temperature changes, and improve heat exchange efficiency, especially achieving efficient precooling at the natural gas inlet stage. The precooling module 120 performs gas-liquid separation on the precooled mixed refrigerant discharged from the precooling heat exchange chamber 105, and returns the gaseous and liquid phase refrigerants to the third and fourth precooling heat exchange tubes 104, respectively, achieving refrigerant self-circulation optimization. At the same time, the precooling refrigerant mixing module 310 can directly supplement or reduce heavy components at the inlet or liquid outlet of the precooling module 120, thereby quickly adjusting the refrigerant composition when the ambient temperature changes, ensuring that the precooling system maintains stability and high performance under a wide range of operating conditions. By injecting the throttled refrigerant into different sections (upper and lower half) of the precooling heat exchange chamber 105, and combining this with the separate reflux of the gas-liquid two-phase refrigerant, the system can maintain stable heat exchange characteristics under different external temperature conditions. For example, in low winter temperatures, the evaporation efficiency of the precooled mixed refrigerant can be improved by reducing the content of heavy components, making full use of natural cold sources; in high summer temperatures, the condensation capacity of the precooled mixed refrigerant can be improved by increasing the content of heavy components, avoiding performance degradation of the device. The multi-path heat exchange combined with the segmented throttling injection design reduces irreversible losses in the heat exchange process and improves the efficiency of cold energy utilization. At the same time, the precise reflux of the gas-liquid two-phase precooled refrigerant and the on-demand distribution of heavy components reduce compressor power consumption and improve the overall energy efficiency of the device. In summary, this embodiment significantly improves the heat exchange efficiency, temperature adaptability, and overall energy efficiency of the precooling system through the structured design of the precooling heat exchanger 111, segmented throttling injection, and flexible precooled mixed refrigerant distribution mechanism. This design is not only suitable for environments with large temperature differences in extremely cold regions, but also provides a reliable guarantee for the efficient, stable and continuous operation of natural gas liquefaction plants applicable to a wide range of environmental temperatures under a wide range of operating conditions.

[0046] Optionally, the precooling module 120 includes a first precooling compressor 121, a first precooling cooler 122, and a first precooling gas-liquid separator 123.

[0047] The inlet of the first precooling compressor 121 is connected to the precooling heat exchange chamber 105; the outlet of the first precooling compressor 121 is connected to the inlet of the first precooling gas-liquid separator 123 via the first precooling cooler 122; the gas phase outlet of the first precooling gas-liquid separator 123 is connected to the inlet of the third precooling heat exchange tube 103, and the liquid phase outlet of the first precooling gas-liquid separator 123 is connected to the inlet of the fourth precooling heat exchange tube. The outlet of the precooling refrigerant mixing module 310 is connected to the inlet of the first precooling compressor 121, and the inlet of the precooling refrigerant mixing module 310 is connected to the liquid phase outlet of the first precooling gas-liquid separator 123.

[0048] In this embodiment, the pre-cooled mixed refrigerant flowing out of the pre-cooling heat exchange chamber 105 first enters the first pre-cooling compressor 121 for pressurization, effectively increasing its pressure and temperature, creating favorable conditions for subsequent cooling and separation. The compressed pre-cooled mixed refrigerant is cooled by the first pre-cooling cooler 122, making full use of the ambient cold source or external cooling medium for efficient heat exchange, reducing the system cooling load, and realizing the step utilization of energy. The first pre-cooling gas-liquid separator 123 efficiently separates the cooled pre-cooled mixed refrigerant. Its gas phase outlet is connected to the third pre-cooling heat exchange tube 103 (mainly used in the upper half of the pre-cooling heat exchange chamber 105), and its liquid phase outlet is connected to the fourth pre-cooling heat exchange tube 104 (mainly used in the lower half). This design ensures that the gas and liquid refrigerants are accurately delivered to different sections of the pre-cooling heat exchanger 111 according to their physical properties, thereby optimizing the heat exchange process and improving the efficiency of cold energy utilization. The outlet of the pre-cooling refrigerant blending module 310 is connected to the inlet of the first pre-cooling compressor 121, allowing direct replenishment of heavy components into the compression stage and rapid adjustment of the overall composition of the circulating pre-cooling mixed refrigerant. The inlet of the pre-cooling refrigerant blending module 310 is connected to the liquid phase outlet of the first pre-cooling gas-liquid separator 123, allowing extraction of excess heavy components from the liquid phase outlet to maintain component balance. This bidirectional blending mechanism enables the device to dynamically optimize the composition of the pre-cooling mixed refrigerant according to changes in ambient temperature, ensuring optimal performance over a wide temperature range from -50℃ to 30℃. The compression, cooling, and separation process design effectively stabilizes the refrigerant pressure and phase state; the bidirectional blending mechanism can promptly balance the content of heavy components, preventing efficiency reduction or equipment problems caused by component imbalance; and the device possesses stronger anti-interference capabilities, enabling it to adapt to significant temperature changes in extremely cold regions.

[0049] Optionally, the precooling module 120 may also include a second precooling compressor 124, a second precooling cooler 125, and a second precooling gas-liquid separator 126.

[0050] The gas phase outlet of the first precooling gas-liquid separator 123 is connected to the inlet of the second precooling compressor 124. The outlet of the second precooling compressor 124 is connected to the inlet of the second precooling gas-liquid separator 126 via the second precooling cooler 125. The gas phase outlet of the second precooling gas-liquid separator 126 is connected to the inlet of the third precooling heat exchange tube 103, and the liquid phase outlet of the second precooling gas-liquid separator 126 is connected to the inlet of the fourth precooling heat exchange tube 104. The liquid phase outlet of the second precooling gas-liquid separator 126 is also connected to the inlet of the precooling refrigerant mixing module 310.

[0051] In this embodiment, the gaseous refrigerant separated by the first pre-cooling gas-liquid separator 123 may still carry a small amount of liquid droplets or heavy components. After being re-pressurized by the second pre-cooling compressor 124 and cooled by the second pre-cooling cooler 125, it enters the second pre-cooling gas-liquid separator 126 for deep separation. After two stages of separation, the gaseous refrigerant returning from the gaseous outlet of the second-stage gas-liquid separator to the third pre-cooling heat exchange tube 103 has higher purity and greater dryness. This effectively prevents the liquid phase from being carried into the upper half of the pre-cooling heat exchange chamber 105, thereby significantly improving the heat exchange efficiency and stability of the upper half of the pre-cooling heat exchanger 111 and avoiding efficiency loss and equipment erosion caused by liquid compression or two-phase flow. The liquid outlet of the second pre-cooling gas-liquid separator 126 is not only connected to the fourth pre-cooling heat exchange tube 104, but also directly connected to the inlet of the pre-cooling refrigerant preparation module 310. This design allows the liquid refrigerant separated in the second stage, rich in heavy components, to be directly guided to the pre-cooling refrigerant preparation module 310. The pre-cooling refrigerant blending module 310 can more accurately monitor and recover excess heavy components in the system, especially when the ambient temperature decreases and it is necessary to reduce heavy components. This provides a direct channel for the efficient removal of excess heavy components. It achieves bidirectional fine control of the heavy component content within the unit (both replenishment and recovery are possible), enabling the pre-cooled refrigerant mixture to adapt to changes in external temperature more quickly and accurately. The two-stage separation and compression design allows the system to handle a wider range of refrigerant gas-liquid mixing. Whether under high temperature and high load conditions in summer or low temperature and light load conditions in winter, the system maintains stable pressure and flow rate through the two-stage process, demonstrating excellent operational flexibility and anti-interference capabilities.

[0052] In some embodiments, the precooling refrigerant mixing module 310 includes a first precooling refrigerant mixing tank 311 and a second precooling refrigerant mixing tank 312.

[0053] The outlets of the first precooling refrigerant mixing tank 311 and the second precooling refrigerant mixing tank 312 are both connected to the inlet of the first precooling compressor 121; the inlet of the first precooling refrigerant mixing tank 311 is connected to the liquid phase outlet of the second precooling gas-liquid separator 126 and the outlet of the second precooling compressor 124; and the inlet of the second precooling refrigerant mixing tank 312 is connected to the liquid phase outlet of the first precooling gas-liquid separator 123 and the outlet of the second precooling compressor 124.

[0054] In this embodiment, the first precooling refrigerant mixing tank 311 and the second precooling refrigerant mixing tank 312 can store different types or concentrations of heavy components. The outlets of both tanks are connected to the inlet of the first precooling compressor 121. This allows for the precise injection of different types of heavy components into the precooling cycle as needed, based on changes in ambient temperature. This rapidly adjusts the overall composition of the precooling refrigerant mixture in the system, improving response speed and control accuracy. By adopting a dual mixing tank design and optimizing its inlet and outlet connections, this embodiment achieves graded storage, precise recovery, and on-demand injection of heavy components. This not only significantly improves the system's adaptability to wide temperature differences in extremely cold regions but also significantly reduces energy consumption and maintenance costs by optimizing refrigerant utilization and operational stability. This provides a crucial guarantee for the efficient and continuous operation of natural gas liquefaction plants suitable for a wide range of ambient temperatures in extreme environments.

[0055] Optionally, the liquid phase outlet of the first precooling gas-liquid separator 123 is equipped with a first regulating valve 501, and the liquid phase outlet of the second precooling gas-liquid separator 126 is equipped with a second regulating valve 502. The outlet of the first precooling refrigerant mixing tank 311 is equipped with a fifth regulating valve 505, and the outlet of the second precooling refrigerant mixing tank 312 is equipped with a sixth regulating valve 506. The outlet of the second precooling compressor 124 is connected to the inlet of the second precooling refrigerant mixing tank 312 through a fourth regulating valve 504. The outlet of the second precooling compressor 124 is also connected to the inlet of the first precooling refrigerant mixing tank 311 through a third regulating valve 503.

[0056] It should be noted that each of the above-mentioned regulating valves has both an on and off state. The opening and closing of each regulating valve can be adjusted as needed to achieve the addition and recovery of heavy components in the pre-cooled refrigerant mixture.

[0057] In some embodiments of the present invention, the cryogenic hybrid refrigeration system 200 includes a cryogenic heat exchange module 210 and a cryogenic module 220.

[0058] The cryogenic heat exchange module 210 includes a cryogenic heat exchanger 211, a first cryogenic throttling valve 212, and a second cryogenic throttling valve 213. A cryogenic heat exchange chamber 204 is formed within the cryogenic heat exchanger 211, and a first cryogenic heat exchange tube 201, a second cryogenic heat exchange tube 202, and a third cryogenic heat exchange tube 203 are installed within the cryogenic heat exchange chamber 204. The inlet end of the first cryogenic heat exchange tube 201 is connected to the outlet end of the first pre-cooling heat exchange tube 101, and the natural gas outlet of the cryogenic heat exchanger 211 is used to discharge liquefied natural gas. The outlet end of the second cryogenic heat exchange tube 202 is connected to the upper half of the cryogenic heat exchange chamber 204 through the first cryogenic throttling valve 212; the outlet end of the third cryogenic heat exchange tube 203 is connected to the lower half of the cryogenic heat exchange chamber 204 through the second cryogenic throttling valve 213.

[0059] The cryogenic module 220 includes a first cryogenic compressor, a first cryogenic cooler, and a first cryogenic gas-liquid separator 223. The inlet end of the first cryogenic compressor is connected to the cryogenic heat exchange chamber 204, and the outlet end of the first cryogenic compressor is connected to the inlet end of the second precooling heat exchange tube 102 through the first cryogenic cooler. The outlet end of the second precooling heat exchange tube 102 is connected to the inlet end of the first cryogenic gas-liquid separator 223. The gas phase outlet of the first cryogenic gas-liquid separator 223 is connected to the inlet end of the second cryogenic heat exchange tube 202, and the liquid phase outlet of the first cryogenic gas-liquid separator 223 is connected to the inlet end of the third cryogenic heat exchange tube 203.

[0060] The cryogenic refrigerant mixing module 320 is used to store heavy components in the cryogenic mixed refrigerant. The inlet of the cryogenic refrigerant mixing module 320 is connected to the liquid phase outlet of the first cryogenic gas-liquid separator 223, and the outlet of the cryogenic refrigerant mixing module 320 is connected to the inlet of the first cryogenic compressor.

[0061] In this embodiment, the cryogenic heat exchanger 211 employs a multi-pipeline design (first to third cryogenic heat exchange tubes) and segmented throttling (first and second cryogenic throttling valves 213). This allows the pre-cooled natural gas to enter the first cryogenic heat exchange tube 201 for further cooling and liquefaction. Meanwhile, the cryogenic mixed refrigerant is injected into the upper and lower halves of the heat exchange chamber through the two throttling valves, achieving precise temperature zone control and gradient cooling to ensure efficient and stable liquefaction of the natural gas to the target temperature. The cryogenic mixed refrigerant from the outlet of the first cryogenic compressor, after being cooled by the first cryogenic cooler, enters the second pre-cooling heat exchange tube 102 for pre-cooling, fully utilizing the cooling capacity of the pre-cooling mixed refrigeration system 100, reducing the cooling load of the cryogenic mixed refrigeration system 200, and significantly improving the overall system energy efficiency. The first cryogenic gas-liquid separator 223 delivers the gaseous and liquid refrigerants to the second and third cryogenic heat exchange tubes 203 respectively, ensuring that each phase of refrigerant enters the most suitable section of the heat exchanger, thus improving heat exchange efficiency.

[0062] Optionally, the cryogenic module 220 also includes a second cryogenic compressor 224 and a second cryogenic cooler 225; the outlet of the first cryogenic cooler is connected to the inlet end of the second precooling heat exchange tube 102 in sequence through the second cryogenic compressor 224 and the second cryogenic cooler 225.

[0063] In this embodiment, the two-stage compression achieves a higher pressure ratio and a lower exhaust temperature. The cryogenic mixed refrigerant at the outlet of the first cryogenic compressor is initially cooled by the first cryogenic cooler before entering the second cryogenic compressor 224 for further pressurization, and finally fully cooled by the second cryogenic cooler 225. This process significantly improves the pressure level and refrigeration potential of the cryogenic mixed refrigerant, enabling it to provide lower temperatures and greater cooling capacity in the cryogenic heat exchanger 211, thereby ensuring that natural gas is efficiently and deeply liquefied.

[0064] Optionally, the cryogenic refrigerant mixing module includes a cryogenic refrigerant mixing tank. A seventh regulating valve 507 is installed on the pipeline between the inlet of the cryogenic refrigerant mixing tank and the liquid phase outlet of the first cryogenic gas-liquid separator 223. An eighth regulating valve 508 is installed at the outlet of the cryogenic refrigerant mixing tank. An eighth regulating valve 508 is also installed on the pipeline between the inlet of the cryogenic refrigerant mixing tank and the inlet of the first cryogenic compressor.

[0065] Each of the above-mentioned regulating valves has an on state and a closed state. The opening and closing of each regulating valve can be adjusted according to actual needs to add heavy components of cryogenic mixed refrigerant to the first cryogenic compressor, or to recover heavy components of cryogenic mixed refrigerant from the liquid phase outlet of the first cryogenic gas-liquid separator 223.

[0066] In some embodiments of the present invention, the natural gas liquefaction apparatus suitable for a wide ambient temperature range further includes a first air cooler 400. The inlet of the first air cooler 400 is supplied with the natural gas to be liquefied, and the outlet of the first air cooler 400 is connected to the natural gas inlet of the pre-cooling mixing refrigeration system 100. The first air cooler 400 provides initial cooling of the natural gas to be liquefied.

[0067] Specifically, the outlet of the first air cooler 400 is connected to the natural gas inlet of the first pre-cooling heat exchanger 101.

[0068] like Figure 3 As shown, for example, taking an ambient temperature of -30°C, the natural gas to be liquefied is purified to a temperature of approximately 25°C. The purified natural gas enters the first air cooler 400 and is cooled to below -15°C. After passing through the pre-cooling heat exchanger 111, it is cooled to approximately -70°C. Then, it undergoes liquefaction and subcooling in the cryogenic heat exchanger 211, reaching a temperature of -155°C before exiting the cryogenic heat exchanger 211. After throttling, it enters the liquefied natural gas storage tank.

[0069] The low-pressure pre-cooled mixed refrigerant exiting the pre-cooling heat exchange chamber 105 of the pre-cooling heat exchanger 111, with a temperature of approximately -10°C, enters the first pre-cooling compressor 121 and is compressed to 1 MPa. The first pre-cooling cooler 122 then cools it to -15°C, and it enters the first pre-cooling gas-liquid separator 123 for gas-liquid separation. The gaseous pre-cooled mixed refrigerant exiting the gas phase outlet of the first pre-cooling gas-liquid separator 123 enters the second pre-cooling compressor 124 and is compressed to 3 MPa. It then enters the second pre-cooling cooler 125 and is cooled to -15°C. The pre-cooled mixed refrigerant then enters the second gas-liquid separator for gas-liquid separation. The separated liquid pre-cooled mixed refrigerant enters the fourth pre-cooling heat exchange tube 104 and is throttled to approximately -45°C, providing cooling for the lower half of the pre-cooling heat exchange chamber 105. The separated gaseous pre-cooled mixed refrigerant enters the third pre-cooling heat exchange tube 103 and is throttled to approximately -70°C, providing cooling for the upper half of the pre-cooling heat exchange chamber 105.

[0070] The low-pressure cryogenic mixed refrigerant coming out of the cryogenic heat exchange chamber 204 of the cryogenic heat exchanger 211 has a temperature of about -75°C. It enters the first cryogenic compressor and is compressed to about 1MPa. After being cooled by the first cryogenic cooler, it enters the second cryogenic compressor 224 and is compressed to 3MPa. It is then cooled to -15°C by the second cryogenic cooler 225. The cryogenic mixed refrigerant is a high-pressure gas phase. The high-pressure gaseous cryogenic mixed refrigerant enters the second precooling heat exchange tube 102 in the precooling heat exchange chamber 105 and is cooled to about -70°C. Then it enters the first cryogenic gas-liquid separator 223 for gas-liquid separation. The separated liquid refrigerant enters the third cryogenic heat exchange tube 203 and is cooled to about -120°C for throttling, providing cooling capacity for the lower half of the cryogenic heat exchange chamber 204. The separated gaseous cryogenic mixed refrigerant enters the second cryogenic heat exchange tube 202 and is cooled to about -155°C for throttling, providing cooling capacity for the upper half of the cryogenic heat exchange chamber 204.

[0071] For example, when the ambient temperature rises from -30°C to -20°C, the pre-cooling mixed refrigeration system 100 has insufficient cooling capacity. If the composition of the pre-cooling mixed refrigerant is not adjusted, the natural gas liquefaction rate will decrease by 3%. By using the refrigerant blending system 300 to make the pre-cooling mixed refrigerant ratio heavier, that is, by adding heavier components to the pre-cooling mixed refrigerant or reducing lighter components, the refrigeration temperature can be lowered and the cooling capacity increased.

[0072] The heavy refrigerant is added to the first precooling compressor 121 through the first precooling refrigerant mixing tank 311. As the heavy refrigerant in the precooling mixed refrigerant increases, the precooling temperature is adjusted to -65℃.

[0073] After the precooling temperature is increased, the cryogenic mixed refrigerant composition of the cryogenic mixed refrigeration system 200 increases with the addition of heavy refrigerant components. Heavy refrigerant components are added to the cryogenic mixed refrigerant through the cryogenic refrigerant mixing tank. As the heavy refrigerant component of the cryogenic mixed refrigerant increases, the cooling capacity of the cryogenic mixed refrigeration system 200 increases.

[0074] With the above adjustments, the natural gas liquefaction rate is only 1.5% lower than when the ambient temperature is -30°C.

[0075] For example, when the ambient temperature drops from -30°C to -40°C, the pre-cooling mixed refrigeration system 100 has excess cooling capacity, but the pre-cooling temperature only decreases by 1°C. If the refrigerant composition is not adjusted, the natural gas liquefaction rate remains unchanged. By using the refrigerant blending system 300 to lighten the proportion of the pre-cooling mixed refrigerant, the pre-cooling temperature is lowered.

[0076] The pre-cooled mixed refrigerant in the first pre-cooling gas-liquid separator 123 is discharged into the second pre-cooling refrigerant mixing tank 312, and then a portion of the liquid refrigerant in the second pre-cooling gas-liquid separator 126 is discharged into the first pre-cooling refrigerant mixing tank 311. As the heavy refrigerant in the pre-cooled mixed refrigerant decreases and the light component increases, the pre-cooling temperature is adjusted to -74℃.

[0077] After the pre-cooling temperature decreases, the cryogenic mixed refrigerant composition of the cryogenic mixed refrigeration system 200 decreases in heavy components and increases in light components. A portion of the liquid refrigerant in the first cryogenic gas-liquid separator 223 is discharged into the cryogenic refrigerant mixing tank, while the corresponding amount of light components is increased.

[0078] With adjustments, the natural gas liquefaction rate increased by 1.3% compared to when the ambient temperature was -30°C.

[0079] like Figure 4 As shown, a second aspect of the present invention provides a natural gas liquefaction method. This natural gas liquefaction method is used in any of the above embodiments of a natural gas liquefaction apparatus suitable for a wide ambient temperature range. The natural gas liquefaction method includes: S10. Obtain the current ambient temperature; S20. When the current ambient temperature is higher than the previously obtained ambient temperature, add heavy components of precooling mixed refrigerant to precooling mixed refrigerant system 100 and heavy components of cryogenic mixed refrigerant to cryogenic mixed refrigerant system 200. When the current ambient temperature is lower than the previously obtained ambient temperature, recover the heavy components of the precooled mixed refrigerant and the heavy components of the cryogenic mixed refrigerant.

[0080] In this embodiment, by acquiring the ambient temperature, changes in the external environment (such as the large temperature difference between day and night or between winter and summer in extremely cold regions) can be sensed in a timely manner, and the refrigerant composition can be dynamically adjusted to ensure that the liquefaction process always proceeds under optimal conditions. Adding heavy components when the temperature rises can prevent excessively high refrigerant condensation pressure and decreased refrigeration efficiency due to increased ambient temperature, maintaining sufficient refrigeration capacity and heat exchange stability of the system. Reducing heavy components when the temperature falls can fully utilize the low-temperature environment's cold source, lower the refrigerant evaporation temperature, reduce compressor power consumption, and achieve energy-saving operation. Through closed-loop control linked to ambient temperature, energy efficiency losses caused by temperature fluctuations in a fixed-component refrigerant (such as summer overload or excessive refrigeration capacity in winter) are eliminated, significantly improving the system's average annual energy efficiency ratio. Reducing the content of heavy components in low-temperature environments can directly lower the refrigerant's boiling point, reduce compressor energy consumption, and extend equipment life.

[0081] Optionally, after obtaining the current ambient temperature, the control device compares the current ambient temperature with the previously obtained ambient temperature. If the current ambient temperature is higher than the previously obtained ambient temperature, the control device controls the refrigerant mixing system 300 to add heavy components of the pre-cooled mixed refrigerant to the pre-cooled mixed refrigeration system 100 and heavy components of the cryogenic mixed refrigerant to the cryogenic mixed refrigeration system 200. If the current ambient temperature is lower than the previously obtained ambient temperature, the control device controls the refrigerant mixing system 300 to recover the heavy components of the pre-cooled mixed refrigerant and the cryogenic mixed refrigerant.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A natural gas liquefaction device suitable for a wide range of ambient temperatures, characterized in that, include: A pre-cooling mixed refrigeration system (100) has a natural gas inlet for supplying natural gas to be liquefied, and the natural gas entering the pre-cooling mixed refrigeration system (100) exchanges heat with the pre-cooling mixed refrigerant; A cryogenic hybrid refrigeration system (200) is provided, wherein the natural gas inlet of the cryogenic hybrid refrigeration system (200) is connected to the natural gas outlet of the precooling hybrid refrigeration system (100), and the natural gas outlet of the cryogenic hybrid refrigeration system (200) is used to discharge liquefied natural gas; the natural gas entering the cryogenic hybrid refrigeration system (200) exchanges heat with the cryogenic hybrid refrigerant; A refrigerant mixing system (300) is connected to the precooling mixed refrigeration system (100) and the cryogenic mixed refrigeration system (200) for increasing the content of heavy components in the precooling mixed refrigerant and the cryogenic mixed refrigerant when the ambient temperature rises, and for decreasing the content of heavy components in the precooling mixed refrigerant and the cryogenic mixed refrigerant when the ambient temperature falls.

2. The natural gas liquefaction device suitable for a wide ambient temperature range according to claim 1, characterized in that, The refrigerant mixing system (300) includes: The precooling refrigerant mixing module (310) is connected to the precooling mixed refrigeration system (100) and is used to increase the content of heavy components in the precooling mixed refrigerant when the ambient temperature rises, and also to decrease the content of heavy components in the precooling mixed refrigerant when the ambient temperature falls. The cryogenic refrigerant mixing module (320) is connected to the cryogenic hybrid refrigeration system (200) and is used to increase the content of heavy components in the cryogenic hybrid refrigerant when the ambient temperature rises, and also to decrease the content of heavy components in the cryogenic hybrid refrigerant when the ambient temperature falls.

3. The natural gas liquefaction device suitable for a wide ambient temperature range according to claim 2, characterized in that, The precooling hybrid refrigeration system (100) includes: A precooling heat exchange module (110) includes a precooling heat exchanger (111), a first precooling throttling valve (112), and a second precooling throttling valve (113). A precooling heat exchange chamber (105) is formed inside the precooling heat exchanger (111), and a first precooling heat exchange tube (101), a third precooling heat exchange tube (103), and a fourth precooling heat exchange tube (104) are provided inside the precooling heat exchange chamber (105). The natural gas inlet of the first precooling heat exchange tube (101) is used to supply natural gas to be liquefied. The outlet end of the third precooling heat exchange tube (103) is connected to the upper half of the precooling heat exchange chamber (105) through the first precooling throttling valve (112), and the outlet end of the fourth precooling heat exchange tube (104) is connected to the lower half of the precooling heat exchange chamber (105) through the second precooling throttling valve (113). A precooling module (120) is provided, with its inlet end connected to the precooling heat exchange chamber (105) for processing the precooled mixed refrigerant discharged from the precooling heat exchange chamber (105) and discharging precooled gaseous refrigerant and precooled liquid refrigerant; the gaseous outlet of the precooling module (120) is connected to the inlet end of the third precooling heat exchange tube (103), and the liquid outlet of the precooling module (120) is connected to the inlet end of the fourth precooling heat exchange tube; The precooling refrigerant mixing module (310) is used to store the heavy components in the precooling mixed refrigerant. The outlet end of the precooling refrigerant mixing module (310) is connected to the inlet end of the precooling module (120), and the outlet end of the precooling refrigerant mixing module (310) is connected to the liquid phase outlet of the precooling module (120).

4. The natural gas liquefaction device suitable for a wide ambient temperature range according to claim 3, characterized in that, The precooling module (120) includes: The inlet of the first precooling compressor (121) is connected to the precooling heat exchange chamber (105); The first precooling cooler (122) and the first precooling gas-liquid separator (123) are connected. The outlet of the first precooling compressor (121) is connected to the inlet of the first precooling gas-liquid separator (123) through the first precooling cooler (122). The gas phase outlet of the first precooling gas-liquid separator (123) is connected to the inlet of the third precooling heat exchange tube (103), and the liquid phase outlet of the first precooling gas-liquid separator (123) is connected to the inlet of the fourth precooling heat exchange tube. The outlet of the precooling refrigerant mixing module (310) is connected to the inlet of the first precooling compressor (121), and the inlet of the precooling refrigerant mixing module (310) is connected to the liquid phase outlet of the first precooling gas-liquid separator (123).

5. The natural gas liquefaction device suitable for a wide ambient temperature range according to claim 4, characterized in that, The precooling module (120) also includes: The second precooling compressor (124) has its gas phase outlet connected to the inlet of the first precooling gas-liquid separator (123); The second precooling cooler (125) and the second precooling gas-liquid separator (126) are connected. The outlet of the second precooling compressor (124) is connected to the inlet of the second precooling gas-liquid separator (126) through the second precooling cooler (125). The gas phase outlet of the second precooling gas-liquid separator (126) is connected to the inlet of the third precooling heat exchange tube (103). The liquid phase outlet of the second precooling gas-liquid separator (126) is connected to the inlet of the fourth precooling heat exchange tube (104). The liquid phase outlet of the second precooling gas-liquid separator (126) is also connected to the inlet of the precooling refrigerant mixing module (310).

6. The natural gas liquefaction device suitable for a wide ambient temperature range according to claim 5, characterized in that, The pre-cooling refrigerant preparation module (310) includes: The first precooling refrigerant mixing tank (311) and the second precooling refrigerant mixing tank (312) are connected to the inlet of the first precooling compressor (121). The inlet of the first precooling refrigerant mixing tank (311) is connected to the liquid phase outlet of the second precooling gas-liquid separator (126) and the outlet of the second precooling compressor (124). The inlet of the second precooling refrigerant mixing tank (312) is connected to the liquid phase outlet of the first precooling gas-liquid separator (123) and the outlet of the second precooling compressor (124).

7. The natural gas liquefaction device suitable for a wide ambient temperature range according to claim 3, characterized in that, The precooling heat exchange chamber (105) is further provided with a second precooling heat exchange tube (102); the cryogenic hybrid refrigeration system (200) includes: Cryogenic heat exchange module (210) includes a cryogenic heat exchanger (211), a first cryogenic throttling valve (212), and a second cryogenic throttling valve (213); a cryogenic heat exchange chamber (204) is formed inside the cryogenic heat exchanger (211), and a first cryogenic heat exchange tube (201), a second cryogenic heat exchange tube (202), and a third cryogenic heat exchange tube (203) are installed inside the cryogenic heat exchange chamber (204); the inlet end of the first cryogenic heat exchange tube (201) is connected to the inlet end of the second cryogenic heat exchange tube (203). The outlet end of a precooling heat exchange tube (101) is connected to the natural gas outlet of the cryogenic heat exchanger (211) tube for discharging liquefied natural gas; the outlet end of the second cryogenic heat exchange tube (202) is connected to the upper half of the cryogenic heat exchange chamber (204) through the first cryogenic throttle valve (212); the outlet end of the third cryogenic heat exchange tube (203) is connected to the lower half of the cryogenic heat exchange chamber (204) through the second cryogenic throttle valve (213); The cryogenic module (220) includes a first cryogenic compressor, a first cryogenic cooler, and a first cryogenic gas-liquid separator (223); the inlet end of the first cryogenic compressor is connected to the cryogenic heat exchange chamber (204), the outlet end of the first cryogenic compressor is connected to the inlet end of the second precooling heat exchange tube (102) through the first cryogenic cooler, and the outlet end of the second precooling heat exchange tube (102) is connected to the inlet of the first cryogenic gas-liquid separator (223); the gas phase outlet of the first cryogenic gas-liquid separator (223) is connected to the inlet end of the second cryogenic heat exchange tube (202), and the liquid phase outlet of the first cryogenic gas-liquid separator (223) is connected to the inlet end of the third cryogenic heat exchange tube (203); The cryogenic refrigerant mixing module (320) is used to store the heavy components in the cryogenic mixed refrigerant. The inlet of the cryogenic refrigerant mixing module (320) is connected to the liquid phase outlet of the first cryogenic gas-liquid separator (223), and the outlet of the cryogenic refrigerant mixing module (320) is connected to the inlet end of the first cryogenic compressor.

8. The natural gas liquefaction apparatus suitable for a wide ambient temperature range according to claim 7, characterized in that, The cryogenic module (220) also includes: The second cryogenic compressor (224) and the second cryogenic cooler (225) are connected in sequence through the second cryogenic compressor (224) and the second cryogenic cooler (225) to the inlet end of the second precooling heat exchange tube (102).

9. The natural gas liquefaction apparatus suitable for a wide ambient temperature range according to any one of claims 1 to 8, characterized in that, The precooling mixed refrigerant includes at least two of methane, ethane, ethylene, propane, and butane; the cryogenic mixed refrigerant includes at least two of nitrogen, methane, ethane, ethylene, and propane.

10. A method for liquefying natural gas, characterized in that, For a natural gas liquefaction apparatus suitable for a wide ambient temperature range as described in any one of claims 1 to 9, the natural gas liquefaction method comprises: Get the current ambient temperature; When the current ambient temperature is higher than the previously obtained ambient temperature, heavy components of precooling mixed refrigerant are added to the precooling mixed refrigeration system (100), and heavy components of cryogenic mixed refrigerant are added to the cryogenic mixed refrigeration system (200). When the current ambient temperature is lower than the previously obtained ambient temperature, recover the heavy components of the precooled mixed refrigerant and the heavy components of the cryogenic mixed refrigerant.

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