Natural gas energy recovery system

Abstract

The application provides a natural gas residual energy recycling system, which comprises a cold energy unit, a liquefaction unit and at least one cold exchange unit, wherein the cold energy unit comprises a cold energy pipeline and at least one cold device connected to the cold energy pipeline, the cold energy pipeline is connected between a first natural gas pipeline and a second natural gas pipeline, the gas pressure in the first natural gas pipeline is greater than that in the second natural gas pipeline; the liquefaction unit comprises a liquefaction pipeline and a liquid storage tank connected to each other; and the at least one cold exchange unit is connected between the cold energy pipeline and the liquefaction pipeline. The cold energy unit, the liquefaction unit and the cold exchange unit solve the problems of low residual energy recycling efficiency and low residual energy use efficiency in the field of natural gas transmission, and also solve the problem of low types of recycled energy in the natural gas residual energy recycling system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas transmission, and in particular to a natural gas residual energy recycling system. BACKGROUND

[0002] The description in this part only provides background information related to the present application disclosure, and does not constitute prior art.

[0003] In the field of natural gas transmission, natural gas is generally transported by long-distance pipeline with high pressure and large diameter. After reaching the destination, the pressure is reduced by the pressure regulating valve, and after the pressure is reduced to meet the standard, the natural gas is input into the gas pipe network for urban household or industrial use. However, when reducing the pressure of high-pressure natural gas, the pressure regulating valve is usually used for rough pressure reduction, resulting in waste of pressure energy and cold energy generated during pressure reduction possessed by high-pressure natural gas. Therefore, the utilization of pressure energy possessed by high-pressure natural gas is one of the problems to be solved in the current energy structure transformation.

[0004] The existing natural pressure energy utilization technical scheme has certain problems. The utilization mode of pressure energy is relatively single, and the recovery efficiency is low. In the prior art, an expander is usually used to reduce the pressure of high-pressure natural gas. In the process of pressure reduction, the pressure energy can also be used to generate electricity, and the electrical energy can be used in other industrial systems. However, the recovery of pressure energy by the expander is limited by the recovery efficiency of the expander. The cold energy in the expansion process of high-pressure natural gas is wasted, and the recovery efficiency cannot be further improved. In other embodiments, the cold energy generated during pressure reduction can also be directly used for cooling work of other heat cycle systems. However, this scheme also only improves the recovery efficiency of the residual energy of high-pressure natural gas by using external equipment, and is still limited by the use efficiency of the external equipment and the installation site, transportation distance and structure of the recovery device. The actual residual energy utilization feasibility is low, and the actual utilization efficiency of the residual energy of natural gas is still at a low level.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical scheme of the present application, and for the convenience of understanding by those skilled in the art. The above technical scheme cannot be considered as known by those skilled in the art only because it is described in the background section of the present application. SUMMARY

[0006] The purpose of the present application is to provide a natural gas residual energy recycling system, which solves the problems of low residual energy recovery efficiency and low residual energy utilization efficiency in the field of natural gas transmission, and also solves the problem of low types of recovered energy in the natural gas residual energy recycling system.

[0007] The above implementation purposes of the present application are mainly realized by the following technical scheme:

[0008] The present application provides a natural gas energy recycling system, comprising:

[0009] a cold energy unit having a cold energy pipeline and at least one cold utilization mechanism connected to the cold energy pipeline, the cold energy pipeline being connected between a first natural gas pipeline and a second natural gas pipeline, the gas pressure in the first natural gas pipeline being greater than that in the second natural gas pipeline;

[0010] a liquefaction unit having a liquefaction pipeline and a liquid storage tank connected thereto;

[0011] at least one cold exchange unit connected between the cold energy pipeline and the liquefaction pipeline.

[0012] In an embodiment, the cold exchange unit has a cold absorption mechanism connected to the cold energy pipeline and at least one cold release mechanism connected to the liquefaction pipeline.

[0013] In an embodiment, the cold release mechanisms are multiple, and the cold exchange unit further has at least one energy supplement mechanism disposed in the liquefaction pipeline, the at least one energy supplement mechanism being located between two adjacent cold release mechanisms.

[0014] In an embodiment, the energy supplement mechanism comprises a first expander connected to the liquefaction pipeline and a cold supplement structure, the cold supplement structure being connected to multiple cold release mechanisms, and the cold supplement structure being located at a downstream end of the first expander.

[0015] In an embodiment, the liquefaction pipeline is provided with a first gas-liquid separator, the first gas-liquid separator being disposed between two adjacent cold release mechanisms, the first gas-liquid separator having a mixed gas inlet, a gas outlet and a liquid outlet, the gas outlet being connected to the energy supplement mechanism, and the liquid outlet being connected to the cold release mechanism located at a downstream end of the first gas-liquid separator.

[0016] In an embodiment, the cold exchange unit further has a second expander, the second expander being disposed in the cold energy pipeline, and the second expander being located at an upstream end of the cold absorption mechanism.

[0017] In an embodiment, the cold utilization mechanism has a third expander disposed in the cold energy pipeline and a cold utilization structure connected between the cold energy pipeline and a heat circulation mechanism.

[0018] In an embodiment, the cold energy pipeline is connected with the second natural gas pipeline, and a heating mechanism is arranged at the connection position of the cold energy pipeline and the second natural gas pipeline.

[0019] In an embodiment, the at least one third expander is arranged at an upstream end of an inlet of the liquefaction pipeline.

[0020] In an embodiment, the cold energy pipeline is connected with the second natural gas pipeline, and a heating mechanism is arranged at the connection position of the cold energy pipeline and the second natural gas pipeline.

[0021] In an embodiment, an expansion valve is arranged on the liquefaction pipeline, and the expansion valve is arranged at a connection position of the liquefaction pipeline and the liquid storage tank.

[0022] In an embodiment, a second gas-liquid separator is arranged between the expansion valve and the liquid storage tank, and the second gas-liquid separator divides the liquefaction pipeline into a liquid-phase storage pipeline and a gas-phase discharge pipeline.

[0023] Compared with the prior art, the technical scheme has the following characteristics and advantages:

[0024] The natural gas residual energy recycling system can realize the output of high-pressure natural gas for use in cities and towns and the preparation of LNG (liquefied natural gas) for storage through the cold energy pipeline and the liquefaction pipeline connected with the cold energy pipeline. In addition, the natural gas residual energy recycling system is combined with the cold energy utilization structure arranged on the cold energy pipeline and the expander arranged upstream of the cold energy utilization structure, so that the electric energy and the cold energy generated by the expansion can be recycled for use in other industrial equipment. Furthermore, the natural gas residual energy recycling system is combined with at least one cold energy exchange unit, so that the cold energy generated by the expansion of the high-pressure natural gas can be further used for the liquefaction of the natural gas in the liquefaction pipeline. Moreover, the natural gas residual energy recycling system is combined with the energy supplement mechanism arranged on the liquefaction pipeline, so that the high-pressure natural gas can be expanded to generate electricity and recycle cold energy, which can be used for the liquefaction of the natural gas upstream of the energy supplement mechanism, thereby further improving the liquefaction efficiency of the natural gas residual energy recycling system. The natural gas residual energy recycling system has a simple structure, does not need to be connected with multiple cold energy utilization devices, and can be arranged and processed only at the natural gas destination, thereby improving the installation simplicity. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a pipeline structure diagram of the natural gas residual energy recycling system.

[0026] REFERENCE SIGNS

[0027] 1. Cold energy unit; 11. Cold energy pipeline; 12. Cold utilization mechanism; 121. Third expander; 122. Cold utilization structure; 1221. First heat exchange structure; 1222. Second heat exchange structure;

[0028] 2. Liquidization unit; 21. Liquidization pipeline; 211. Expansion valve; 212. Second gas-liquid separator; 213. Liquid phase storage pipeline; 214. Gas phase discharge pipeline; 215. First branch pipeline; 216. Second branch pipeline; 22. Liquid storage tank;

[0029] 3. Cold exchange unit; 31. Cold absorption mechanism; 32. Cold release mechanism; 33. Energy supplement mechanism; 331. First expander; 332. Cold supplement structure; 34. Second expander;

[0030] 4. First gas-liquid separator; 41. Mixed gas inlet; 42. Gas outlet; 43. Liquid outlet;

[0031] 5. Heat cycle mechanism;

[0032] 6. Heating mechanism; 61. Third heat exchange structure; 62. Fourth heat exchange structure;

[0033] 7. Solar energy pipeline;

[0034] 8. First natural gas pipeline;

[0035] 9. Second natural gas pipeline. DETAILED DESCRIPTION

[0036] In order to make the personnel in the technical field better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without creative labor should belong to the protection scope of the present application.

[0037] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intervening element. The terms "vertical", "horizontal", "left", "right", and similar expressions used herein are for illustrative purposes only and are not intended to be limiting.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0039] As shown in the drawings, Figure 1 The application provides a natural gas residual energy recycling system, comprising:

[0040] a cold energy unit 1 having a cold energy pipeline 11 and at least one refrigeration mechanism 12 connected to the cold energy pipeline 11, the cold energy pipeline 11 being connected between a first natural gas pipeline 8 and a second natural gas pipeline 9, the gas pressure in the first natural gas pipeline 8 being greater than that in the second natural gas pipeline 9;

[0041] a liquefaction unit 2 having a liquefaction pipeline 21 and a liquid storage tank 22 connected thereto;

[0042] at least one cold exchange unit 3 connected between the cold energy pipeline 11 and the liquefaction pipeline 21.

[0043] The natural gas residual energy recycling system provided by the application can recycle the pressure energy of natural gas through the cold energy unit 1, convert the pressure energy into cold energy and electric energy, and output natural gas of various standard pressures for daily use at the same time. Meanwhile, the liquefaction unit 2 in the application can convert gaseous natural gas into liquefied natural gas and store it in the liquid storage tank 22. Further, the liquefaction unit 2 can recycle the cold energy in the cold energy unit 1 through the cold exchange unit 3 for liquefying natural gas in the liquefaction unit 2.

[0044] Specifically, the cold energy pipeline 11 is connected between two natural gas pipelines with a pressure difference, the natural gas pipeline with a higher pressure is communicated with the natural gas pipeline with a lower pressure through the cold energy pipeline 11. In this embodiment, the cold energy pipeline 11 is connected between the first natural gas pipeline 8 and the second natural gas pipeline 9, and the natural gas in the first natural gas pipeline 8 is delivered into the second natural gas pipeline 9 through the cold energy pipeline 11. At least one refrigeration mechanism 12 is arranged on the cold energy pipeline 11, one end of the refrigeration mechanism 12 is connected to the heat circulation mechanism 5, and the other end of the refrigeration mechanism 12 absorbs and utilizes the cold energy generated in the process of pressure change of natural gas. One end of the liquefaction pipeline 21 of the liquefaction unit 2 is connected to the liquid storage tank 22, the other end of the liquefaction pipeline 21 is connected to the cold energy pipeline 11, and the two ends of the cold exchange unit 3 are connected to the cold energy pipeline 11 and the liquefaction pipeline 21 respectively. The cold exchange unit 3 transmits the cold energy generated in the cold energy pipeline 11 to the liquefaction pipeline 21 through an energy transmission medium, so as to refrigerate and liquefy the natural gas in the liquefaction pipeline 21.

[0045] In a specific embodiment, as shown in the drawings,Figure 1 As shown, the cold exchange unit 3 has a cold absorbing mechanism 31 connected in the cold energy pipeline 11 and at least one cold releasing mechanism 32 connected in the liquefaction pipeline 21.

[0046] Through the cold absorbing mechanism 31, the cold energy in the cold energy pipeline 11 can be absorbed, and the temperature of the natural gas in the cold energy pipeline 11 rises after passing through the cold absorbing mechanism 31. Through the cold releasing mechanism 32, the cold energy absorbed by the cold absorbing mechanism 31 can be released, and the temperature of the natural gas in the liquefaction pipeline 21 drops after passing through the cold releasing mechanism 32.

[0047] Specifically, the device used by the cold absorbing mechanism 31 and the cold releasing mechanism 32 is not specifically limited, the cold absorbing mechanism 31 is arranged in the cold energy pipeline 11, the cold releasing mechanism 32 is arranged in the liquefaction pipeline 21, and the cold absorbing mechanism 31 and the cold releasing mechanism 32 are in communication with each other. In this embodiment, two cold releasing mechanisms 32 are arranged in the liquefaction pipeline 21, the two cold releasing mechanisms 32 are arranged upstream and downstream along the liquefaction pipeline 21, the two cold releasing mechanisms 32 and the cold absorbing mechanism 31 are in communication, the outlet of the cold absorbing mechanism 31 is connected with the inlet of the cold releasing mechanism 32 located downstream, and the outlet of the cold releasing mechanism 32 located upstream is connected with the inlet of the cold absorbing mechanism 31, so as to first deliver more cold energy to the natural gas located downstream, and promote the further liquefaction of the gaseous natural gas. In other embodiments, three cold releasing mechanisms 32 can also be arranged in the liquefaction pipeline 21, and the number of cold releasing mechanisms 32 is not specifically limited.

[0048] In a specific embodiment, as shown in Figure 1 The cold releasing mechanism 32 is multiple, and the cold exchange unit 3 further has at least one energy supplementing mechanism 33 arranged in the liquefaction pipeline 21, and the at least one energy supplementing mechanism 33 is located between every two adjacent cold releasing mechanisms 32.

[0049] The energy supplementing mechanism 33 can utilize the cold energy generated by the pressure energy of the natural gas in the liquefaction pipeline 21 to further supplement the cold energy of other mechanisms in the cold exchange unit 3, further improve the liquefaction capacity of the liquefaction pipeline 21 to the natural gas, and further improve the refrigeration effect of the cold exchange unit 3 as a whole.

[0050] Specifically, the energy supplement mechanism 33 is arranged in the liquefaction pipeline 21, and the energy supplement mechanism 33 is located between two adjacent cold release mechanisms 32. In this embodiment, one energy supplement mechanism 33 is arranged in the liquefaction pipeline 21, and the energy supplement mechanism 33 is located between two cold release mechanisms 32. In other embodiments, two energy supplement mechanisms 33 can also be arranged in the liquefaction pipeline 21, and one energy supplement mechanism 33 is arranged between two adjacent cold release mechanisms 32. In this embodiment, the cold energy of the energy supplement mechanism 33 is used to supplement the cold energy of the cold release mechanism 32, so that the cold release mechanism 32 located upstream of the energy supplement mechanism 33 can maintain good refrigeration capacity. In other embodiments, the energy supplement mechanism 33 can also supplement the cold energy of the cold absorption mechanism 31, so as to improve the cold absorption capacity of the cold absorption mechanism 31. The specific arrangement of the energy supplement mechanism 33 is not limited.

[0051] In a specific embodiment, as shown in Figure 1 The energy supplement mechanism 33 includes a first expander 331 connected in the liquefaction pipeline 21 and a cold supplement structure 332 connected with the plurality of cold release mechanisms 32, and the cold supplement structure 332 is located at the downstream end of the first expander 331.

[0052] The first expander 331 can further release the pressure energy of the natural gas in the liquefaction pipeline 21 and convert it into electrical energy and cold energy. The cold supplement structure 332 can absorb the cold energy released by the first expander 331 and deliver it to the cold release mechanism 32, so as to improve the refrigeration capacity of the cold release mechanism 32.

[0053] Specifically, the first expander 331 and the cold supplement structure 332 are arranged in the liquefaction pipeline 21. The natural gas pressure at the upstream end of the first expander 331 is greater than the natural gas pressure at the downstream end of the first expander 331. The cold supplement structure 332 is arranged at the downstream end of the first expander 331. The cold supplement structure 332 is connected with the plurality of cold release mechanisms 32. In this embodiment, the cold supplement unit 3 has two cold release mechanisms 32, and the two cold release mechanisms 32 are arranged in the liquefaction pipeline 21. The cold supplement structure 332 is arranged between the two cold release mechanisms 32. The outlet of the cold release mechanism 32 located downstream is connected with the inlet of the cold supplement structure 332. The outlet of the cold supplement structure 332 is connected with the inlet of the cold release mechanism 32 located upstream. In other embodiments, the outlet of the cold supplement structure 332 can also be connected with the inlet of the cold release mechanism 32 located downstream. The inlet of the cold supplement structure 332 can also be connected with the outlet of the cold release mechanism 32 located upstream. The specific connection mode of the cold supplement structure 332 and the cold release mechanism 32 is not limited.

[0054] In a specific embodiment, as shown in Figure 1As shown, the liquefaction pipeline 21 is provided with a first gas-liquid separator 4, the first gas-liquid separator 4 is arranged between two adjacent cooling mechanisms 32, the first gas-liquid separator 4 has a mixed gas inlet 41, a gas outlet 42 and a liquid outlet 43, the gas outlet 42 is connected with the energy supplement mechanism 33, and the liquid outlet 43 is connected with the cooling mechanism 32 at the downstream end of the first gas-liquid separator 4.

[0055] The first gas-liquid separator 4 facilitates the separation of gas-liquid medium, so as to send the gaseous natural gas to the energy supplement mechanism 33 to release cold energy, while directly conveying the liquid natural gas to the cooling mechanism 32 for further temperature reduction, avoiding the liquid natural gas returning to gaseous natural gas.

[0056] Specifically, the first gas-liquid separator 4 is arranged in the liquefaction pipeline 21, the upstream end of the first gas-liquid separator 4 is provided with the mixed gas inlet 41, the downstream end of the first gas-liquid separator 4 is provided with the gas outlet 42 and the liquid outlet 43, the gas outlet 42 is connected with one end of the first branch pipeline 215, the liquid outlet 43 is connected with one end of the second branch pipeline 216, the other end of the first branch pipeline 215 and the other end of the second branch pipeline 216 are connected and merged, and the energy supplement mechanism 33 is arranged in the first branch pipeline 215. In this embodiment, the cooling unit 3 has two cooling mechanisms 32, and the cooling mechanism 32 at the downstream end is arranged at the merging position of the first branch pipeline 215 and the second branch pipeline 216; in other embodiments, the number of cooling mechanisms 32 can also be three, at this time, the number of first gas-liquid separators 4 is two, that is, one first gas-liquid separator 4 is arranged between two adjacent cooling mechanisms 32. The number and arrangement of the first gas-liquid separator 4 are not limited.

[0057] In a specific embodiment, as shown in the figure, Figure 1 The cooling unit 3 also has a second expander 34, the second expander 34 is arranged in the cold energy pipeline 11, and the second expander 34 is located at the upstream end of the cold absorption mechanism 31.

[0058] The second expander 34 is used to release and utilize the pressure energy of natural gas in the cold energy pipeline 11 to generate electric energy and cold energy, and the cold energy generated by the second expander 34 is the main cold energy source of the cooling unit 3; specifically, the pressure of natural gas at the upstream end of the second expander 34 is greater than the pressure of natural gas at the downstream end of the second expander 34, and the cold absorption structure is arranged at the downstream end of the second expander 34, and the cold absorption structure is connected with at least one cooling mechanism 32.

[0059] In a specific embodiment, as shown in the figure, Figure 1 The cooling mechanism 12 has a third expander 121 and a cold absorption structure 122, the third expander 121 is arranged in the cold energy pipeline 11, and the cold absorption structure 122 is connected between the cold energy pipeline 11 and the heat circulation mechanism 5.

[0060] The third expander 121 is also used to release the pressure energy of the natural gas in the cold energy pipeline 11, and the third expander 121 can convert the pressure energy into electric energy and cold energy. The cold energy released by the third expander 121 is further utilized by the heat circulation mechanism 5 through the cold structure 122.

[0061] Specifically, the third expander 121 is arranged in the cold energy pipeline 11, and the natural gas pressure at the upstream end of the third expander 121 is greater than the natural gas pressure at the downstream end of the third expander 121. One end of the cold structure 122 is arranged at the downstream end of the third expander 121, and the other end of the cold structure 122 is arranged on the heat circulation mechanism 5.

[0062] In a specific embodiment, as shown in Figure 1 The cold structure 122 has a first heat exchange structure 1221 and a second heat exchange structure 1222 connected in communication. The first heat exchange structure 1221 is arranged in the cold energy pipeline 11, and the second heat exchange structure 1222 is connected to the heat circulation mechanism 5.

[0063] The first heat exchange structure 1221 and the second heat exchange structure 1222 are connected in communication, and the cold structure 122 absorbs the cold energy in the cold energy pipeline 11 through the first heat exchange structure 1221 and releases the cold energy in the cold energy pipeline 11 through the second heat exchange structure 1222. Specifically, the first heat exchange structure 1221 is arranged in the cold energy pipeline 11, and the second heat exchange structure 1222 is arranged on the heat exchanger of the heat circulation mechanism 5 to provide the cold energy for the cooling gas of the heat exchanger.

[0064] In a specific embodiment, as shown in Figure 1 The at least one third expander 121 is located at the upstream end of the inlet of the liquefaction pipeline 21.

[0065] Through the third expander 121, the gaseous natural gas entering the liquefaction pipeline 21 is further released of pressure energy and reduced in temperature, so as to more conveniently reach the required pressure size of the liquid storage tank 22. Meanwhile, the multi-level arrangement of the expanders can reduce the expansion range of the operation of each expander and reduce the working pressure of each expander.

[0066] In the embodiment, the third expander 121 is located at the connection between the cold energy pipeline 11 and the first natural gas pipeline 8, the natural gas pressure at the upstream end of the third expander 121 is greater than the natural gas pressure at the downstream end of the third expander 121, the inlet of the liquefaction pipeline 21 is connected to the cold energy pipeline 11, and the inlet of the liquefaction pipeline 21 is arranged at the downstream end of the third expander 121. In other embodiments, the number of third expanders 121 can also be multiple, and the inlet of the liquefaction pipeline 21 can also be arranged at the downstream end of the multiple third expanders 121. The specific arrangement position of the inlet of the liquefaction pipeline 21 is not limited further.

[0067] In a specific embodiment, as shown in Figure 1 The heating mechanism 6 is connected to the connection between the cold energy pipeline 11 and the second natural gas pipeline 9, the heating mechanism 6 has a third heat exchange structure 61 and a fourth heat exchange structure 62 connected in communication, the third heat exchange structure 61 is connected in the cold energy pipeline 11, and the fourth heat exchange structure 62 is arranged in the solar energy pipeline 7.

[0068] The heating mechanism 6 transmits the heat energy of the solar energy to the cold energy pipeline 11 through the connection with the solar energy pipeline 7, so as to heat the gaseous natural gas in the cold energy pipeline 11 to reach the temperature of the urban use standard, and facilitate the direct delivery of the natural gas to each use unit.

[0069] Specifically, the heating mechanism 6 is connected between the solar energy pipeline 7 and the cold energy pipeline 11, the third heat exchange structure 61 is arranged in the cold energy pipeline 11, and the fourth heat exchange structure 62 is arranged in the solar energy pipeline 7. The fourth heat exchange structure 62 absorbs the heat energy collected by the solar energy pipeline 7, transmits the heat energy to the third heat exchange structure 61 through the heat conduction medium, and releases the heat energy, and the third heat exchange structure 61 releases the heat energy to the cold energy pipeline 11.

[0070] In a specific embodiment, as shown in Figure 1 The expansion valve 211 is arranged on the liquefaction pipeline 21, the expansion valve 211 is located at the connection between the liquefaction pipeline 21 and the liquid storage tank 22, and the outlet pressure of the expansion valve 211 is set to 0.2-0.4 MPa. The expansion valve 211 is used to further release the pressure of the natural gas, and reduce the pressure value of the natural gas to the safe storage pressure value of the liquid storage tank 22. Specifically, the upstream end of the expansion valve 211 is connected to the liquefaction pipeline 21, and the downstream end of the expansion valve 211 is connected to the liquid storage tank 22.

[0071] In a specific embodiment, as shown in Figure 1 The second gas-liquid separator 212 is arranged between the expansion valve 211 and the liquid storage tank 22, the second gas-liquid separator 212 divides the liquefaction pipeline 21 into a liquid phase storage pipeline 213 and a gas phase discharge pipeline 214, the liquid phase storage pipeline 213 is connected to the liquid storage tank 22, and the gas phase discharge pipeline 214 is communicated with the atmosphere.

[0072] The second gas-liquid separator 212 is used to separate the liquefied pipeline 21 into liquid natural gas and gaseous natural gas, so as to avoid that part of the liquid natural gas is converted into gaseous natural gas when passing through the expansion valve 211, and the gaseous natural gas is input into the liquid storage tank 22.

[0073] Specifically, the upstream end of the second gas-liquid separator 212 is connected with the expansion valve 211, and the downstream end of the second gas-liquid separator 212 is respectively connected with one end of the liquid phase storage pipeline 213 and one end of the gaseous phase discharge pipeline 214, wherein the other end of the liquid phase storage pipeline 213 is connected with the liquid storage tank 22 in communication, and the other end of the gaseous phase discharge pipeline 214 is connected with the atmosphere in communication.

[0074] The above specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only for specific embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A natural gas waste energy recovery and utilization system, characterized in that, include: A cooling unit has a cooling pipeline and at least one cooling device connected to the cooling pipeline. The cooling pipeline is connected between a first natural gas pipeline and a second natural gas pipeline, and the gas pressure in the first natural gas pipeline is greater than the gas pressure in the second natural gas pipeline. The liquefaction unit has liquefaction pipelines and a storage tank connected to it; At least one cooling unit is connected between the cooling energy pipeline and the liquefaction pipeline; The cooling unit has a connected cooling absorption mechanism and at least one cooling release mechanism. The cooling absorption mechanism is connected to the cooling energy pipeline, and at least one cooling release mechanism is connected to the liquefaction pipeline. There are multiple cooling release mechanisms. The cooling unit also has at least one energy replenishment mechanism disposed in the liquefaction pipeline, and at least one energy replenishment mechanism is located between two adjacent cooling release mechanisms. The energy replenishment mechanism includes a first expander connected in the liquefaction pipeline and a cooling replenishment structure. The cooling replenishment structure is connected to multiple cooling release mechanisms. The cooling replenishment structure is located downstream of the first expander. The first expander is used to release the pressure energy of the natural gas in the liquefaction pipeline and convert the pressure energy into electrical energy and cold energy. The cooling replenishment structure is used to absorb the cold energy released by the first expander and transport the cold energy released by the first expander to the cooling release mechanism to improve the cooling capacity of the cooling release mechanism. The cooling unit also has a second expander, which is installed in the cooling pipeline and located upstream of the cooling absorption mechanism. The second expander is used to release and utilize the pressure energy of the natural gas in the cooling pipeline to generate electrical energy and cooling energy, and to provide cooling energy for the cooling unit.

2. The natural gas waste energy recovery and utilization system according to claim 1, characterized in that, The liquefaction pipeline is equipped with a first gas-liquid separator, which is located between two adjacent cooling mechanisms. The first gas-liquid separator has a mixed gas inlet, a gas outlet, and a liquid outlet. The gas outlet is connected to the energy replenishment mechanism, and the liquid outlet is connected to the cooling mechanism located downstream of the first gas-liquid separator.

3. The natural gas waste energy recovery and utilization system according to claim 1, characterized in that, The cooling mechanism has a third expander and a cooling structure. The third expander is disposed in the cooling pipeline, and the cooling structure is connected between the cooling pipeline and the heat circulation mechanism.

4. The natural gas waste energy recovery and utilization system according to claim 3, characterized in that, The cooling structure has a first heat exchange structure and a second heat exchange structure that are connected to each other. The first heat exchange structure is disposed in the cooling pipeline, and the second heat exchange structure is connected to the heat circulation mechanism.

5. The natural gas waste energy recovery and utilization system according to claim 3, characterized in that, At least one of the third expanders is located upstream of the inlet of the liquefaction pipeline.

6. The natural gas waste energy recovery and utilization system according to claim 1, characterized in that, A heating mechanism is connected at the connection between the cold energy pipeline and the second natural gas pipeline. The heating mechanism has a third heat exchange structure and a fourth heat exchange structure that are connected to each other. The third heat exchange structure is connected in the cold energy pipeline, and the fourth heat exchange structure is installed in the solar tube.

7. The natural gas waste energy recovery and utilization system according to claim 1, characterized in that, An expansion valve is installed on the liquefaction pipeline. The expansion valve is located at the connection between the liquefaction pipeline and the storage tank. The outlet pressure of the expansion valve is set to 0.2 MPa to 0.4 MPa.

8. The natural gas waste energy recovery and utilization system according to claim 7, characterized in that, A second gas-liquid separator is provided between the expansion valve and the storage tank. The second gas-liquid separator divides the liquefaction pipeline into a liquid phase storage pipeline and a gas phase discharge pipeline. The liquid phase storage pipeline is connected to the storage tank, and the gas phase discharge pipeline is connected to the atmosphere.

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