Liquid nitrogen temperature zone refrigerating system based on LNG (Liquefied Natural Gas) cold energy utilization

Abstract

The invention relates to the technical field of low-temperature refrigeration, in particular to a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, which comprises a refrigerant device, a first heat exchanger, a second heat exchanger and the like, the first heat exchanger forms a first flow channel and a second flow channel, the first flow channel is communicated with the outlet end of the refrigerant device, and the second flow channel is communicated with an LNG pipeline; the second heat exchanger is arranged between the first heat exchanger and the LNG pipeline cold source; a third flow channel and a fourth flow channel are formed in the second heat exchanger, the third flow channel, the LNG pipeline cold source and the fourth flow channel are sequentially connected, and an outlet of the fourth flow channel communicates with the inlet end of the refrigerant device. Cold energy in the LNG pipeline is transferred to the refrigerant through heat exchange, and the refrigerant absorbs the cold energy of LNG, so that the efficiency of a refrigerating system is improved; and the cooled refrigerant is used for keeping the LNG pipeline cold source in a low-temperature state and ensuring long-distance transportation of LNG, or is directly used for producing liquid nitrogen.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature refrigeration, and in particular to a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization. Background Art

[0002] In the existing technology, liquefied natural gas (LNG) is generally gasified by heat exchange with seawater in coastal receiving stations, and then transported to inland cities with demand through long-distance natural gas pipelines. This method not only has an adverse impact on the marine ecological environment, but also fails to fully utilize the high-quality cold energy contained in LNG. However, the geographical distribution of cold energy demand is wide and the scale varies. There is a temporal and spatial mismatch between the supply and demand of cold energy and natural gas. So far, long-distance transmission and distribution of LNG and large-scale utilization of cold energy have not been achieved.

[0003] Therefore, the development of LNG pipeline transportation technology is of great significance. LNG pipeline transportation has the advantages of high energy density, large transportation capacity, and low transportation cost. It can realize large-scale and long-distance natural gas transportation, and can also distribute the high-grade cold energy carried by LNG to the cold energy demand points along the way. At the same time, it can cooperate with superconducting cables to realize the coordinated transportation of "electricity-fuel-cold energy". LNG needs to maintain a low temperature state during transportation, and liquid nitrogen is usually used to provide a low temperature environment. LNG and liquid nitrogen are both easily gasified media, and energy pipelines require strict insulation design. At the same time, sufficient cold sources need to be provided during long-distance pipeline transportation to ensure long-distance transportation of LNG.

[0004] Therefore, how to ensure the efficient use of the high-grade cold energy contained in LNG and ensure the long-distance transportation of LNG, or use it for the direct production of liquid nitrogen, so as to improve the transportation and refrigeration efficiency of LNG. Summary of the invention

[0005] The present invention provides a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, which is used to ensure efficient utilization of high-grade cold energy contained in LNG and ensure long-distance transportation of LNG, or to directly produce liquid nitrogen, thereby improving the transportation and refrigeration efficiency of LNG.

[0006] The present invention provides a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, comprising: A refrigerant device is formed with an outlet end for supplying refrigerant and an inlet end for returning refrigerant; a first heat exchanger, forming a first flow channel and a second flow channel, wherein the first flow channel is connected to the outlet end of the refrigerant device, and the second flow channel is connected to the LNG pipeline; The second heat exchanger is arranged between the first heat exchanger and the LNG pipeline cold source; the second heat exchanger is formed with a third flow channel and a fourth flow channel, the third flow channel and the fourth flow channel are arranged on both sides of the LNG pipeline cold source, and the outlet of the fourth flow channel is connected to the inlet end of the refrigerant device.

[0007] According to the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention, the second heat exchanger is arranged between the first heat exchanger and the LNG pipeline cold source, and the first heat exchanger also forms a fifth flow channel, the first flow channel is connected between the third flow channel and the outlet end of the refrigerant device, and the fifth flow channel is connected between the fourth flow channel and the inlet end of the refrigerant device.

[0008] According to the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention, the refrigerant device includes: a first storage tank, a first compressor, a second compressor, a first oil separator, a first condenser, a second condenser, a first dryer and a third heat exchanger; The third heat exchanger is formed with a sixth flow channel and a seventh flow channel, and the sixth flow channel is connected downstream of the second flow channel; The first storage tank, the first compressor, the first oil separator, the first condenser and the first dryer are sequentially connected to the first flow channel; Another outlet of the first oil separator converges and is connected to an outlet end of the fifth flow channel, and the outlet end of the fifth flow channel is sequentially connected to the second compressor, the second condenser, the seventh flow channel and the first compressor.

[0009] The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention also includes: The annular pipe is wrapped around the outside of the LNG pipeline and is used to fill the LNG pipeline cold source; The first evaporator is arranged between the third flow channel and the fourth flow channel, and exchanges heat with the LNG pipeline cold source in the annular pipeline.

[0010] The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention also includes: A first throttling element is provided between the third flow channel and the LNG pipeline cold source; first temperature sensors, respectively arranged on both sides of the first throttling element along the refrigerant flow direction; The first pressure sensor is arranged at the outlet of the seventh flow channel.

[0011] The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention also includes: A first high-pressure protector is provided between the oil separator and the first condenser; The first charging port is arranged between the first condenser and the first dryer, and is used for charging / discharging the refrigerant in the refrigerant device.

[0012] The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention further includes: a fourth heat exchanger arranged between the first heat exchanger and the refrigerant device, and the second heat exchanger arranged between the first heat exchanger and the LNG pipeline cold source; The fourth heat exchanger is formed with an eighth flow channel and a ninth flow channel, and the outlet end of the refrigerant device, the eighth flow channel, the first flow channel, the third flow channel, the LNG pipeline cold source, the fourth flow channel, the ninth flow channel and the inlet end of the refrigerant device are connected in sequence.

[0013] According to the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention, the refrigerant device includes: a second storage tank, a third condenser, a second dryer, a condensation separator, a third compressor and a second oil separator; The ninth flow channel, the third compressor, the second oil separator, the third condenser, the second dryer, the condensation separator and the eighth flow channel are connected in sequence; The second storage tank is disposed between the second oil separator and the third condenser.

[0014] The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention also includes: a mixer, disposed between the ninth flow channel and the third compressor and connected to another outlet of the condensation separator; The second throttling element is arranged between the other outlet of the condensation separator and the mixer.

[0015] The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided by the present invention also includes: Liquid nitrogen tank, used to store cold source of LNG pipeline; A second evaporator is disposed between the third flow channel and the fourth flow channel and exchanges heat with the LNG pipeline cold source in the liquid nitrogen tank; A third throttling element is provided between the third flow channel and the liquid nitrogen tank; The second temperature sensor is respectively arranged on both sides of the third throttling element along the refrigerant flow direction; a second pressure sensor, disposed at the outlet of the ninth flow channel; A second high-pressure protector is provided between the second oil separator and the third condenser; The second filling port is arranged at the inlet end of the third compressor.

[0016] The present invention provides a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, which includes: a refrigerant device, a first heat exchanger, a second heat exchanger, etc., the refrigerant device is formed with an outlet end for supplying high-temperature and high-pressure refrigerant and an inlet end for returning low-temperature and low-pressure refrigerant; the first heat exchanger forms a first flow channel and a second flow channel, the first flow channel is connected to the outlet end of the refrigerant device, and the second flow channel is connected to the LNG pipeline; the second heat exchanger is arranged between the first heat exchanger and the LNG pipeline cold source; the second heat exchanger is formed with a third flow channel and a fourth flow channel, the third flow channel, the LNG pipeline cold source and the fourth flow channel are connected in sequence, and the outlet of the fourth flow channel is connected to the inlet end of the refrigerant device. The present invention provides a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, the first heat exchanger is connected to the LNG pipeline, the cold energy in the LNG pipeline is transferred to the refrigerant through heat exchange, the refrigerant absorbs the cold energy of LNG, thereby improving the efficiency of the refrigeration system; the second heat exchanger is connected to the LNG pipeline cold source, and the cooled refrigerant is used to maintain the LNG pipeline cold source at a low temperature state, to ensure the long-distance transportation of LNG, or to be directly used for the production of liquid nitrogen. It can be seen that the present invention can make full use of the cold energy contained in LNG, on the one hand to provide cold energy for the refrigerant, and on the other hand to provide a low temperature state for long-distance transportation of LNG pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a structural schematic diagram of a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided in Example 1 of the present invention.

[0019] Figure 2 It is a structural schematic diagram of a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization provided in Example 2 of the present invention.

[0020] Figure 3 It is a cross-sectional schematic diagram of an annular pipeline and an LNG pipeline provided in Example 1 of the present invention.

[0021] Figure 4 It is a cross-sectional schematic diagram of another annular pipeline and LNG pipeline provided in Example 1 of the present invention.

[0022] Reference numerals: 101: second compressor; 102: first compressor; 1031: first condenser; 1032: second condenser; 104: first oil separator; 105: first storage tank; 106: first electric regulating valve; 107: manual regulating valve; 108: first dryer; 109: first heat exchanger; 110: second heat exchanger; 111: first throttling element; 112: first evaporator; 113: liquid nitrogen section; 114: LNG section; 115: cryogenic valve; 116: third heat exchanger; 117: first high-pressure protector; 118: first filling port; 119: first temperature sensor; 120: first pressure sensor; 201: third compressor; 202: second oil separator; 203: third condenser; 204: second dryer; 205: fractional condensation separator; 206: second throttling element; 207: mixer; 208: fourth heat exchanger; 211: third throttling element; 212: second evaporator; 213: liquid nitrogen tank; 214: second storage tank; 215: second high-pressure protector; 216: second electric regulating valve; 217: LNG valve; 218: second filling port; 219: second pressure sensor; 220: second temperature sensor; 403: superconducting cable; 404: insulating protective layer. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0024] In the description of the present embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present embodiment and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present embodiment.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this embodiment, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] In this embodiment, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0027] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] Combine the following Figure 1-Figure 4 The present invention describes a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization includes: a refrigerant device, a first heat exchanger 109 and a second heat exchanger 110 .

[0029] The refrigerant device is formed with an outlet end for supplying high-temperature and high-pressure refrigerant and an inlet end for returning low-temperature and low-pressure refrigerant; the first heat exchanger 109 forms a first flow channel and a second flow channel, the first flow channel is connected to the outlet end of the refrigerant device, and the second flow channel is connected to the LNG pipeline; the second heat exchanger 110 is arranged between the first heat exchanger 109 and the LNG pipeline cold source; the second heat exchanger 110 is formed with a third flow channel and a fourth flow channel, the third flow channel and the fourth flow channel are arranged on both sides of the LNG pipeline cold source and allow the refrigerant therein to exchange heat with the LNG pipeline cold source, and the outlet of the fourth flow channel is connected to the inlet end of the refrigerant device.

[0030] Specifically, the refrigerant device has an outlet end for supplying high-temperature and high-pressure refrigerant to the first heat exchanger 109 and the second heat exchanger 110, and also has an inlet end (also a liquid return end) for reflux of low-temperature and low-pressure refrigerant after heat exchange, and the refrigerant can be circulated in the refrigerant device to avoid waste of refrigerant. It should be understood that the temperature and pressure of the high-temperature and high-pressure refrigerant and the low-temperature and low-pressure refrigerant mentioned above are determined according to actual conditions, and the present invention is not limited to a specific temperature and pressure.

[0031] Specifically, the first flow channel in the first heat exchanger 109 exchanges heat with the second flow channel, and the third flow channel in the second heat exchanger 110 exchanges heat with the fourth flow channel. According to different design forms, the connection relationship between the first heat exchanger 109, the second heat exchanger 110 and the refrigerant device is different. Two different arrangements of the first heat exchanger 109 and the second heat exchanger 110 are given in the following embodiments 1 and 2. However, the functions of the first heat exchanger 109 and the second heat exchanger 110 do not change with the different arrangement positions, that is, the first heat exchanger 109 is connected to the LNG pipeline, and the cold energy in the LNG pipeline is transferred to the refrigerant through heat exchange, and the refrigerant absorbs the cold energy of LNG, thereby improving the efficiency of the refrigeration system. The second heat exchanger 110 is connected to the cold source of the LNG pipeline, and the cooled refrigerant is used to maintain the cold source of the LNG pipeline at a low temperature to ensure long-distance transportation of LNG, or to be directly used for the production of liquid nitrogen.

[0032] The present invention provides a liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, which includes: a refrigerant device, a first heat exchanger 109 and a second heat exchanger 110, etc. The refrigerant device is formed with an outlet end for supplying high-temperature and high-pressure refrigerant and an inlet end for returning low-temperature and low-pressure refrigerant; the first heat exchanger 109 forms a first flow channel and a second flow channel, the first flow channel is connected to the outlet end of the refrigerant device, and the second flow channel is connected to the LNG pipeline; the second heat exchanger 110 is arranged between the first heat exchanger 109 and the LNG pipeline cold source; the second heat exchanger 110 is formed with a third flow channel and a fourth flow channel, the third flow channel, the LNG pipeline cold source and the fourth flow channel are connected in sequence, and the outlet of the fourth flow channel is connected to the inlet end of the refrigerant device. The present invention provides a liquid nitrogen temperature zone refrigeration system based on the utilization of LNG cold energy. The first heat exchanger 109 is connected to the LNG pipeline to transfer the cold energy in the LNG pipeline to the refrigerant through heat exchange. The refrigerant absorbs the cold energy of LNG, thereby improving the efficiency of the refrigeration system. The second heat exchanger 110 is connected to the cold source of the LNG pipeline. The cooled refrigerant is used to maintain the cold source of the LNG pipeline at a low temperature to ensure long-distance transportation of LNG, or to directly produce liquid nitrogen. It can be seen that the present invention can make full use of the cold energy contained in LNG, on the one hand to provide cold energy for the refrigerant, and on the other hand to provide a low temperature state for long-distance transportation of LNG pipelines.

[0033] Embodiment 1: like Figure 1 As shown, the second heat exchanger 110 is arranged between the first heat exchanger 109 and the LNG pipeline cold source, and the first heat exchanger 109 also forms a fifth flow channel, the first flow channel (the upper flow channel of the first heat exchanger 109) is connected between the third flow channel (the upper flow channel of the second heat exchanger 110) and the outlet end of the refrigerant device, and the fifth flow channel (the middle flow channel of the first heat exchanger 109) is connected between the fourth flow channel (the lower flow channel of the second heat exchanger 110) and the inlet end of the refrigerant device.

[0034] Preferably, the refrigerant device comprises: a first storage tank 105, a first compressor 102, a second compressor 101, a first oil separator 104, a first condenser 1031, a second condenser 1032, a first dryer 108 and a third heat exchanger 116. The third heat exchanger 116 is formed with a sixth flow channel and a seventh flow channel, and the sixth flow channel (the lower flow channel of the third heat exchanger 116) is connected to the downstream of the second flow channel (the lower flow channel of the first heat exchanger 109); the first storage tank 105, the first compressor 102, the first oil separator 104, the first condenser 1031 and the first dryer 108 are connected to the first flow channel in sequence; the other outlet of the first oil separator 104 is connected to the outlet end of the fifth flow channel, and the outlet end of the fifth flow channel is connected to the second compressor 101, the second condenser 1032, the seventh flow channel (the upper flow channel of the third heat exchanger 116) and the first compressor 102 in sequence. It can be understood that, in this embodiment, the outlet end of the refrigerant device is the outlet end of the first dryer 108 , and the inlet end of the refrigerant device is the inlet end of the second compressor 101 .

[0035] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization in this embodiment further includes: an annular pipeline and a first evaporator 112. The annular pipeline is wrapped around the outside of the LNG pipeline and is used to fill the LNG pipeline cold source; the first evaporator 112 is arranged between the third flow channel and the fourth flow channel, and exchanges heat with the LNG pipeline cold source in the annular pipeline.

[0036] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization of this embodiment further includes: a first throttling element 111, a first temperature sensor 119 and a first pressure sensor 120. The first throttling element 111 is arranged between the third flow channel and the LNG pipeline cold source; the first temperature sensor 119 is respectively arranged on both sides of the first throttling element 111 along the refrigerant flow direction; the first pressure sensor 120 is arranged at the outlet of the seventh flow channel.

[0037] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization in this embodiment further includes: a first high-pressure protector 117 and a first filling port 118. The first high-pressure protector 117 is arranged between the oil separator and the first condenser 1031; the first filling port 118 is arranged between the first condenser 1031 and the first dryer 108, and is used to charge / discharge the refrigerant in the refrigerant device.

[0038] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization of this embodiment further includes: valve components such as a manual regulating valve 107, a first electric regulating valve 106 and a cryogenic valve 115. The manual regulating valve 107 and the first electric regulating valve 106 are arranged on the pipeline connected to the first storage tank 105, and the cryogenic valve 115 is respectively arranged upstream and downstream of the second flow channel. The specific working process of the refrigeration system of this embodiment is as follows: The refrigeration system compresses the refrigerant from a low-temperature and low-pressure gas to a high-temperature and high-pressure gas through the second compressor 101 and the first compressor 102. The condensers (the first condenser 1031 and the second condenser 1032) dissipate heat to the external environment. The first oil separator 104 diverts part of the oil in the pipeline to the inlet of the second compressor 101 to prevent excessive oil from entering the low-temperature section of the system and condensing. The first storage tank 105 cooperates with the first electric regulating valve 106 and the manual regulating valve 107 to adjust the quality of the refrigerant in the system. The first dryer 108 is used to filter impurities in the system to ensure the stability of the refrigeration system operation.

[0039] The first heat exchanger 109 is an intermediate heat exchanger for heat exchange between high-pressure refrigerant, low-pressure refrigerant and LNG. The second heat exchanger 110 is a low-temperature heat exchanger for further heat exchange between high-pressure refrigerant and low-pressure refrigerant. The first throttling element 111 is used to convert the high-temperature and high-pressure refrigerant in the refrigeration pipeline into a low-temperature and low-pressure refrigerant. The first evaporator 112 is used to transfer the cold to the LNG pipeline. The evaporation temperature reaches 70K, and the exergy efficiency of the system is 21.6%, which is more than 50% higher than the efficiency of the same temperature refrigeration system without LNG. The third heat exchanger 116 is a high-temperature heat exchanger for further strengthening the heat exchange between the refrigerant and LNG, so that the temperature of the LNG is raised to room temperature.

[0040] The low-temperature valve 115 is used to adjust the flow rate of LNG used for cold energy in the refrigeration system. The temperature of LNG increases after heat exchange in the intermediate-stage regenerator, and its temperature is raised to room temperature by passing through the high-temperature regenerator, so that its cold energy is fully utilized. The first high-pressure protector 117 is used to prevent excessive pressure in the system from damaging components. The first filling port 118 is used to fill / discharge refrigerant in the refrigeration system. The first temperature sensor 119 and the first pressure sensor 120 are used to monitor the system operation status in real time.

[0041] The LNG energy pipeline is divided into two parts, namely, the liquid nitrogen section 113 and the LNG section 114 (i.e., the LNG pipeline). The liquid nitrogen section 113 is the cold source of the LNG pipeline in this embodiment. The liquid nitrogen section 113 is an annular pipeline filled with liquid nitrogen to maintain the low temperature environment of the LNG section 114. The LNG section 114 has a circular cross-section and is filled with flowing LNG liquid to transport LNG. The energy pipeline can have various forms.

[0042] like Figure 3 As shown, it is a cross-sectional view of an LNG energy pipeline, that is, a schematic cross-sectional view of a liquid nitrogen section 113 and an LNG section 114. The liquid nitrogen section 113 wraps the LNG section 114 inside the LNG pipeline in an annular shape through an annular pipe, and the two are transported in coordination.

[0043] like Figure 4 As shown, it is another cross-sectional view of LNG energy pipeline, that is, the annular pipeline wraps the LNG pipeline and the superconducting cable 403 at the same time, there is an insulating protective layer 404 between the LNG pipeline and the superconducting cable 403, and liquid nitrogen, LNG and superconducting wire are transported in coordination.

[0044] Embodiment 2: like Figure 2 As shown, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization in this embodiment also includes: a fourth heat exchanger 208. The fourth heat exchanger 208 is arranged between the first heat exchanger 109 and the refrigerant device, and the second heat exchanger 110 is arranged between the first heat exchanger 109 and the LNG pipeline cold source. The fourth heat exchanger 208 is formed with an eighth flow channel and a ninth flow channel, and the outlet end of the refrigerant device, the eighth flow channel (the upper flow channel of the fourth heat exchanger 208), the first flow channel (the lower flow channel of the first heat exchanger 109), the third flow channel (the upper flow channel of the second heat exchanger 110), the LNG pipeline cold source, the fourth flow channel (the lower flow channel of the second heat exchanger 110), the ninth flow channel (the lower flow channel of the fourth heat exchanger 208) and the inlet end of the refrigerant device are connected in sequence. The second flow channel (the upper flow channel of the first heat exchanger 109) is connected to the LNG pipeline; Preferably, the refrigerant device comprises: a second storage tank 214, a third condenser 203, a second dryer 204, a condensation separator 205, a third compressor 201 and a second oil separator 202. The ninth flow channel, the third compressor 201, the second oil separator 202, the third condenser 203, the second dryer 204 and the condensation separator 205 are connected to the eighth flow channel in sequence; the second storage tank 214 is arranged between the second oil separator 202 and the third condenser 203.

[0045] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization in this embodiment further includes: a mixer 207 and a second throttling element 206. The mixer 207 is arranged between the ninth flow channel and the third compressor 201, and is connected to the other outlet of the condensation separator 205; the second throttling element 206 is arranged between the other outlet of the condensation separator 205 and the mixer 207. It can be understood that, in this embodiment, the outlet end of the refrigerant device is the outlet end of the condensation separator 205, and the inlet end of the refrigerant device is the inlet end of the mixer 207.

[0046] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization in this embodiment further includes: a liquid nitrogen tank 213, a second evaporator 212, a third throttling element 211, a second temperature sensor 220, a second pressure sensor 219, a second high-pressure protector 215 and a second filling port 218. The liquid nitrogen stored in the liquid nitrogen tank 213 is the LNG pipeline cold source; the second evaporator 212 is arranged between the third flow channel and the fourth flow channel, and exchanges heat with the LNG pipeline cold source in the liquid nitrogen tank 213; the third throttling element 211 is arranged between the third flow channel and the liquid nitrogen tank 213; the second temperature sensor 220 is respectively arranged on both sides of the third throttling element 211 along the refrigerant flow direction; the second pressure sensor 219 is arranged at the outlet of the ninth flow channel; the second high-pressure protector 215 is arranged between the second oil separator 202 and the third condenser 203; the second filling port 218 is arranged at the inlet end of the third compressor 201.

[0047] Preferably, the liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization in this embodiment further includes valve components such as a second electric regulating valve 216 and an LNG valve 217. The second electric regulating valve 216 is provided in the second storage tank 214; the LNG valve 217 is provided upstream and downstream of the first heat exchanger 109, respectively. The specific working process of the refrigeration system in this embodiment is as follows: The refrigeration system compresses the refrigerant from a low-temperature and low-pressure gas to a high-temperature and high-pressure gas through the third compressor 201. The second oil separator 202 returns part of the oil in the pipeline to the inlet of the third compressor 201. The third condenser 203 dissipates heat to the external environment. The second dryer 204 is used to filter impurities in the system. The condensation separator 205 is used to separate the high-boiling-point refrigerant and part of the lubricating oil in the refrigeration pipeline, cool down and reduce the pressure through the second throttling element 206, and then mix with the low-pressure refrigerant through the mixer 207 and return to the inlet of the third compressor 201. The condensation separator 205 separates the The low boiling point refrigerant exists in the form of gas phase, passes through the fourth heat exchanger 208 (which is a high temperature stage regenerator) to exchange heat with the low temperature and low pressure refrigerant for cooling, and then passes through the first heat exchanger 109 to exchange heat with LNG, absorbs the cold energy of LNG for cooling, and the flow rate and flow of LNG are controlled by the LNG valve 217. The high pressure refrigerant after heat exchange with LNG passes through the second heat exchanger 110 (which is a low temperature stage regenerator) for further cooling, and then passes through the third throttling element 211 to cool down the refrigerant and reduce its pressure, and releases the cold energy through the second evaporator 212 to maintain the liquid nitrogen in the liquid nitrogen tank 213 at a low temperature.

[0048] The second storage tank 214 in the refrigeration system cooperates with the second electric regulating valve 216 to adjust the quality of the refrigerant in the system, the second high-pressure protector 215 is used to prevent the excessive pressure in the system from damaging components, the second filling port 218 is used to fill / discharge the refrigerant in the refrigeration system, and the second pressure sensor 219 and the second temperature sensor 220 are used to monitor the system operation status in real time.

[0049] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, i.e., they may be located in one place, or they may be distributed over multiple units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0050] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization, characterized in that: include: A refrigerant device is formed with an outlet end for supplying refrigerant and an inlet end for returning refrigerant; A first heat exchanger (109) is formed with a first flow channel and a second flow channel, wherein the first flow channel is connected to the outlet end of the refrigerant device, and the second flow channel is connected to the LNG pipeline; The second heat exchanger (110) is arranged between the first heat exchanger (109) and the LNG pipeline cold source; the second heat exchanger (110) is formed with a third flow channel and a fourth flow channel, the third flow channel and the fourth flow channel are arranged on both sides of the LNG pipeline cold source, and the outlet of the fourth flow channel is connected to the inlet end of the refrigerant device.

2. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 1 is characterized in that: The second heat exchanger (110) is arranged between the first heat exchanger (109) and the LNG pipeline cold source, and the first heat exchanger (109) also forms a fifth flow channel, the first flow channel is connected between the third flow channel and the outlet end of the refrigerant device, and the fifth flow channel is connected between the fourth flow channel and the inlet end of the refrigerant device.

3. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 2 is characterized in that: The refrigerant device comprises: a first storage tank (105), a first compressor (102), a second compressor (101), a first oil separator (104), a first condenser (1031), a second condenser (1032), a first dryer (108) and a third heat exchanger (116); The third heat exchanger (116) is formed with a sixth flow channel and a seventh flow channel, and the sixth flow channel is connected downstream of the second flow channel; The first storage tank (105), the first compressor (102), the first oil separator (104), the first condenser (1031) and the first dryer (108) are sequentially connected to the first flow channel; The other outlet of the first oil separator (104) converges and is connected to the outlet end of the fifth flow channel, and the outlet end of the fifth flow channel is sequentially connected to the second compressor (101), the second condenser (1032), the seventh flow channel and the first compressor (102).

4. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 3 is characterized in that: Also includes: The annular pipe is wrapped around the outside of the LNG pipeline and is used to fill the LNG pipeline cold source; The first evaporator (112) is arranged between the third flow channel and the fourth flow channel, and exchanges heat with the LNG pipeline cold source in the annular pipeline.

5. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 3 is characterized in that: Also includes: A first throttling element (111) is provided between the third flow channel and the LNG pipeline cold source; First temperature sensors (119) are respectively arranged on both sides of the first throttling element (111) along the refrigerant flow direction; The first pressure sensor (120) is arranged at the outlet of the seventh flow channel.

6. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to any one of claims 3 to 5, characterized in that: Also includes: a first high-pressure protector (117), arranged between the oil separator and the first condenser (1031); A first filling port (118) is provided between the first condenser (1031) and the first dryer (108) and is used for filling / discharging the refrigerant in the refrigerant device.

7. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 1 is characterized in that: Also includes: The fourth heat exchanger (208) is provided between the first heat exchanger (109) and the refrigerant device, and the second heat exchanger (110) is provided between the first heat exchanger (109) and the LNG pipeline cold source; The fourth heat exchanger (208) is formed with an eighth flow channel and a ninth flow channel, and the outlet end of the refrigerant device, the eighth flow channel, the first flow channel, the third flow channel, the LNG pipeline cold source, the fourth flow channel, the ninth flow channel and the inlet end of the refrigerant device are connected in sequence.

8. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 7 is characterized in that: The refrigerant device comprises: a second storage tank (214), a third condenser (203), a second dryer (204), a condensation separator (205), a third compressor (201) and a second oil separator (202); The ninth flow channel, the third compressor (201), the second oil separator (202), the third condenser (203), the second dryer (204), the condensation separator (205), and the eighth flow channel are connected in sequence; The second storage tank (214) is arranged between the second oil separator (202) and the third condenser (203).

9. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 8 is characterized in that: Also includes: a mixer (207), disposed between the ninth flow channel and the third compressor (201), and connected to another outlet of the condensation separator (205); The second throttling element (206) is arranged between the other outlet of the condensation separator (205) and the mixer (207).

10. The liquid nitrogen temperature zone refrigeration system based on LNG cold energy utilization according to claim 8 or 9, characterized in that: Also includes: Liquid nitrogen tank (213), used for storing cold source of LNG pipeline; A second evaporator (212) is disposed between the third flow channel and the fourth flow channel and exchanges heat with an LNG pipeline cold source in the liquid nitrogen tank (213); A third throttling element (211) is provided between the third flow channel and the liquid nitrogen tank (213); Second temperature sensors (220) are respectively arranged on both sides of the third throttling element (211) along the refrigerant flow direction; a second pressure sensor (219), disposed at the outlet of the ninth flow channel; a second high-pressure protector (215), disposed between the second oil separator (202) and the third condenser (203); The second filling port (218) is arranged at the inlet end of the third compressor (201).

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