Liquefied gas cold energy utilization system and method

Abstract

The application provides a liquefied gas cold energy utilization system and method, wherein the system comprises a liquefied gas storage device, a first pressure reducing valve, a gas-liquid separation device, a primary heat exchange device and a delivery header. The liquid liquefied gas in the liquefied gas storage device is partially flashed by the first pressure reducing valve; the gaseous and liquid liquefied gas is separated by the gas-liquid separation device, and the gaseous liquefied gas directly enters the header; the liquid liquefied gas enters the primary heat exchange device, is gasified after heat exchange with a heat exchange medium and enters the header; and the header is combined with the gaseous liquefied gas and is delivered to a combustion equipment. The device realizes partial flashing by controlling the pressure reduction process, can guarantee stable gas supply of the combustion equipment while utilizing the phase change endothermic refrigeration of the liquefied gas, realizes the step-by-step utilization of energy and is suitable for application scenarios such as motor homes, long-distance trucks and the like using liquefied gas as fuel.

Description

TECHNICAL FIELD

[0001] The present application relates to liquefied gas cold energy recovery, in particular to a liquefied gas cold energy utilization system and method. BACKGROUND

[0002] Liquefied petroleum gas (LPG) is a commonly used clean energy, and its core components are propane and butane, which can be stored in special steel cylinders at room temperature. When LPG gasifies, it will absorb environmental heat, and propane and butane can be used as refrigerants. However, existing bottled LPG is usually used as fuel, and there is no perfect cold energy recovery solution.

[0003] Existing cold energy recovery and utilization systems are usually designed around liquefied natural gas (LNG) (such as the solutions disclosed in patents CN114651148A, CN117190625A, and CN102967099A). The core component of LNG is methane, which usually needs to be cooled to -162℃ to form an ultralow-temperature liquid for transportation and is stored in a vacuum insulated tank. LNG is mainly used for energy supply in industrial scenarios such as ships and large storage tanks. The existing cold energy utilization system directly exchanges heat between low-temperature LNG and a cooling medium, so it relies on an ultralow-temperature environment and large insulation equipment, which is bulky and costly, and cannot be applied to small scenarios such as recreational vehicles and long-distance trucks that use liquefied gas as a power source.

[0004] Therefore, how to design a fuel supply and cold energy recovery integrated system suitable for small scenarios based on the characteristics of liquefied petroleum gas has become a problem to be solved. SUMMARY

[0005] The purpose of the present application is to provide a liquefied gas cold energy utilization system and method that is suitable for small scenarios and can ensure fuel supply and achieve cold energy recovery and utilization.

[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows: a liquefied gas cold energy utilization system, comprising:

[0007] a liquefied gas storage device, the internal pressure of which is maintained at 0.5-1.2 MPa, and the bottom of the liquefied gas storage device is provided with a liquid outlet;

[0008] a first pressure reducing valve, the input end of which is connected to the liquid outlet of the liquefied gas storage device, for reducing the pressure of the liquefied gas to 0.2-0.45 MPa and flashing part of the liquefied gas;

[0009] a gas-liquid separation device, the input end of which is connected to the output end of the first pressure reducing valve, the gas-liquid separation device being provided with a first gas phase outlet and a first liquid phase outlet, the first gas phase outlet being connected to a delivery main pipe, and the first liquid phase outlet being connected to a primary heat exchange device;

[0010] The primary heat exchange device comprises a first medium pipeline for flowing through a heat exchange medium and a first liquefied gas pipeline for flowing through liquefied gas, a first heat exchange structure is arranged between the first medium pipeline and the first liquefied gas pipeline, the input end of the first liquefied gas pipeline is connected with the first liquid phase outlet of the gas-liquid separation device, and the output end of the first liquefied gas pipeline is communicated with the delivery main pipe;

[0011] The delivery main pipe is connected to the first gas phase outlet of the gas-liquid separation device at one end and connected to the combustion equipment at the other end, and is used for converging the gaseous liquefied gas output by the gas-liquid separation device and the gaseous liquefied gas output by the primary heat exchange device, and delivering the converged gaseous liquefied gas to the combustion equipment.

[0012] In the above scheme, the "liquefied gas" refers to liquefied petroleum gas (LPG), and the core components are propane (R290) and butane (R600). Because propane and butane have the phase change characteristics of being easily pressurized and liquefied at room temperature, and the volume is greatly reduced after liquefaction, the storage device (such as a steel cylinder) can be maintained at a pressure of 0.5-1.2 MPa at room temperature, realizing high-density liquid storage, without the need for additional low-temperature refrigeration equipment, and adapting to the storage needs of house cars, long-distance trucks and other scenes.

[0013] The outlet of the existing liquefied gas cylinder is usually arranged at the top, and the liquefied gas is discharged under the action of pressure. During the discharge process, the liquefied gas is naturally gasified due to the decrease in pressure, and can be used for combustion equipment such as a stove. The gasification in this process absorbs heat, but because the gasification process is dispersed, this part of cold energy is difficult to be effectively utilized.

[0014] In the present scheme, the liquid outlet is arranged at the bottom of the liquefied gas storage device, so that as long as there is still not completely gasified liquid liquefied gas in the storage device, the medium discharged from the bottom liquid outlet can be stably maintained in a liquid state.

[0015] The first pressure reducing valve is used to reduce the pressure from 0.5-1.2 MPa of the storage device to 0.2-0.45 MPa, so that the saturation temperature of propane and butane is reduced, and part of the liquefied gas absorbs heat and becomes a gas, which is a partial "flash evaporation". After flash evaporation, the liquefied gas forms a gas-liquid mixed state.

[0016] The partial flash evaporation has two effects, one is to reduce the temperature of the liquefied gas for subsequent heat exchange, and the other is to ensure that a certain proportion of liquefied gas is continuously input to the combustion equipment to ensure stable combustion gas supply and reduce the influence of fluctuations of the primary heat exchange device.

[0017] The gas-liquid separation device is used to separate liquefied gas in a gas-liquid mixed state, and prevent liquid liquefied gas from entering the combustion equipment. The pressure inside the gas-liquid separation device is consistent with the outlet pressure of the first pressure reducing valve, and is also kept at 0.2-0.45 MPa, so as to control the flash evaporation ratio and ensure that most of the liquefied gas remains in a liquid state.

[0018] Due to the flash evaporation heat absorption, the temperature of the liquid liquefied gas in the gas-liquid separation device will be significantly reduced compared to the initial temperature, and the temperature reduction is about 20-25℃ when the pressure is reduced from 0.5 MPa to 0.2 MPa.

[0019] The liquid liquefied gas enters the subsequent primary heat exchange device and exchanges heat with the heat exchange medium to realize refrigeration. The heat exchange process includes both liquid temperature rise heat absorption and gasification heat absorption. The heat exchange medium can be water, air, etc. The primary heat exchange device can be integrated into the interior of a refrigerator, air conditioner, etc. At the same time, during the heat exchange process, the liquefied gas absorbs heat and gasifies, and then enters the delivery main pipe to be delivered to the combustion equipment together with the gaseous liquefied gas obtained by flash evaporation, so as to realize both combustion gas supply and cold energy utilization.

[0020] In a further technical solution, the gas-liquid separation device is a horizontally placed cylindrical structure with a length-diameter ratio of 3-5, the first gas phase outlet is arranged at the top, the first liquid phase outlet is arranged at the bottom, and a liquid droplet isolation net is arranged at the first gas phase outlet to ensure that liquid liquefied gas droplets cannot enter the gaseous pipeline and prevent liquid liquefied gas from entering the combustion equipment to cause safety hazards. In order to avoid excessive flash evaporation and reduce cold energy loss, a thermal insulation layer is arranged on the outer wall of the gas-liquid separation device.

[0021] In a further technical solution, the first liquefied gas pipeline of the primary heat exchange device is a horizontally arranged tube bundle with gradually increasing pipe diameters, the pipe diameter ratio of the rear end to the front end of the first liquefied gas pipeline is 1.5:1, and the first heat exchange structure is an aluminum fin covering the first liquefied gas pipeline. Since the liquid liquefied gas will gradually gasify after heat absorption, gradually increasing the pipe diameter can ensure that the pressure in the pipeline is stable and the flow rate is maintained within a reasonable range, thereby avoiding impact on the delivery main pipe.

[0022] In a further technical solution, the system further comprises an intermediate separator, the output end of the first liquefied gas pipeline is connected to the input end of the intermediate separator, the intermediate separator is provided with a second gas phase outlet and a second liquid phase outlet, the second gas phase outlet is connected to the delivery main pipe, and the first liquefied gas pipeline communicates with the delivery main pipe through the second gas phase outlet of the intermediate separator. When the liquefied gas flow is large, the primary heat exchange device may not be able to gasify all the liquid liquefied gas in time, and therefore the intermediate separator is arranged to separate the liquid and gaseous liquefied gas, so as to ensure that only the gaseous liquefied gas enters the delivery main pipe.

[0023] Further technical solutions, the intermediate separator is a vertically placed cylindrical structure, the length-diameter ratio is 1-2, the second gas phase outlet is arranged at the top, the second liquid phase outlet is arranged at the bottom, the input end is arranged at the middle along the tangent direction, the second gas phase outlet is provided with a liquid droplet isolation net, and the outer wall of the intermediate separator is provided with a heat preservation layer. Since the output liquefied gas of the primary heat exchange device may be in a gas-liquid mixed state, the vertically arranged intermediate separator can separate the liquid and gaseous liquefied gas by using gravity. The heat preservation layer can prevent the liquid liquefied gas from further gasification in the intermediate separator by absorbing heat, thereby wasting cold energy.

[0024] Further technical solutions, the system further comprises:

[0025] A second pressure reducing valve, the input end of which is connected with the second liquid phase outlet of the intermediate separator, is used to reduce the pressure of the liquefied gas to 0.1-0.2 MPa and promote partial liquefied gas to flash.

[0026] A secondary heat exchange device, comprising a second medium pipeline for circulating a heat exchange medium and a second liquefied gas pipeline for circulating liquefied gas, a second heat exchange structure is arranged between the second medium pipeline and the second liquefied gas pipeline, the input end of the second liquefied gas pipeline is connected with the output end of the second pressure reducing valve, and the output end is connected to the delivery main pipe.

[0027] By arranging the second pressure reducing valve and the secondary heat exchange device, the second partial flash can be carried out, and the liquefied gas that has not been gasified can be fully utilized, which is suitable for the case that the gas consumption of the combustion equipment is large, for example, a long-distance truck using liquefied gas as a power energy source, and the engine is used as a combustion equipment, and the liquefied gas needs to be used continuously. In this scenario, the liquefied gas consumption is large, and by using the primary heat exchange device and the secondary heat exchange device for staged pressure reduction and refrigeration, the cold energy of the liquefied gas can be fully utilized.

[0028] Further technical solutions, the second liquefied gas pipeline of the secondary heat exchange device comprises a plurality of branch pipes, the second heat exchange structure comprises heat exchange plates and corrugated fins, the corrugated fins are attached to the upper and lower surfaces of the heat exchange plates, the plurality of branch pipes pass through the inside of the heat exchange plates and form continuous flow channels, the input ends of the plurality of branch pipes are connected to the output end of the second pressure reducing valve, and the output ends are connected to the delivery main pipe after being connected in series. The ratio of the total pipe diameter of the plurality of branch pipes to the pipe diameter of the front end inlet is 2:1, and the heat exchange area of the second heat exchange structure is 2-4 m 2 .

[0029] In order to fully gasify the liquid liquefied gas, the secondary heat exchange device needs to be fully heat exchanged, so that as much liquefied gas as possible can be gasified through the structure of the heat exchange plates and the corrugated fins. Since the volume expands after gasification, the ratio of the total pipe diameter to the pipe diameter of the front end inlet is designed to be 2:1, so that the gas pressure in the pipe remains stable.

[0030] Further technical solutions, the system further comprises:

[0031] The first nozzle pressure expansion device is connected to the intersection of the first gas phase outlet of the gas-liquid separation device, the second gas phase outlet of the intermediate separator and the delivery main pipe, and is used for stabilizing the pressure of the plurality of gaseous media after merging.

[0032] The second nozzle pressure expansion device is connected to the intersection of the second liquefied gas pipeline output end of the secondary heat exchange device and the delivery main pipe, and is used for increasing the pressure of the gaseous liquefied gas after the secondary heat exchange to the pressure adapted to the delivery main pipe.

[0033] Further technical solutions, the system further comprises a gas storage tank, the gas storage tank is connected in series between the delivery main pipe and the combustion equipment, a pressure relief valve is arranged on the gas storage tank, and the opening pressure of the pressure relief valve is 0.6-0.8 MPa. By arranging the gas storage tank, the pressure and flow of the gaseous liquefied gas entering the combustion equipment can be stabilized, and problems such as large and small combustion flames and flameout caused by gas fluctuation can be avoided, so that the operation stability of the combustion equipment is ensured. In addition, the gas storage tank can also mix the liquefied gas uniformly. Since the saturated vapor pressure of propane is higher than that of butane, the gas flashed out for the first time is mainly propane, and the gaseous output by the primary heat exchange device and the secondary heat exchange device is gradually increased. The liquefied gas can be fully mixed and uniform after entering the gas storage tank, which is beneficial to full combustion.

[0034] According to another aspect of the present application, a liquefied gas cold energy utilization method is also provided, comprising the following steps:

[0035] S1: liquefied gas storage, storing the liquefied gas in a liquefied gas storage device with an internal pressure maintained at 0.5-1.2 MPa, and arranging a liquid outlet at the bottom of the liquefied gas storage device;

[0036] S2: primary pressure reduction flash evaporation, reducing the pressure of the liquid liquefied gas output from the liquid outlet of the liquefied gas storage device to 0.2-0.45 MPa through a first pressure reduction valve, so as to cause part of the liquid liquefied gas to flash evaporate into gaseous state;

[0037] S3: primary gas-liquid separation, introducing the gas-liquid mixed liquefied gas treated in step S2 into a gas-liquid separation device to separate the first gaseous liquefied gas and the first liquid liquefied gas, and conveying the first gaseous liquefied gas to the delivery main pipe through the first gas phase outlet of the gas-liquid separation device;

[0038] S4: primary heat exchange and cold extraction, introducing the first liquid liquefied gas separated in step S3 into the first liquefied gas pipeline of the primary heat exchange device, so that the first liquid liquefied gas exchanges heat with the heat exchange medium flowing in the first medium pipeline of the primary heat exchange device, the first liquid liquefied gas is gasified to form the second gaseous liquefied gas after absorbing heat, and the second gaseous liquefied gas is conveyed to the delivery main pipe through the first liquefied gas pipeline output end.

[0039] S5: gaseous conveying combustion, the first gaseous liquefied gas of step S3 and the second gaseous liquefied gas of step S4 are converged through a conveying main pipe, and the converged gaseous liquefied gas is conveyed to a combustion device for combustion.

[0040] Further technical solutions, between step S4 and step S5, further comprising the following steps:

[0041] S41: intermediate separation, the second gaseous liquefied gas (containing residual liquid liquefied gas that is not completely gasified) output by the first liquefied gas pipeline in step S4 is introduced into an intermediate separator to separate third gaseous liquefied gas and second liquid liquefied gas, and the third gaseous liquefied gas is conveyed to the conveying main pipe through the second gas phase outlet of the intermediate separator;

[0042] S42: secondary pressure reduction flash evaporation, the second liquid liquefied gas separated in step S41 is reduced in pressure to 0.1-0.2 MPa through a second pressure reduction valve to cause part of the second liquid liquefied gas to flash evaporate into a gaseous state;

[0043] S43: secondary heat exchange for cooling, the gas-liquid mixed liquefied gas after step S42 is introduced into the second liquefied gas pipeline of the secondary heat exchange device, so that the gas-liquid mixed liquefied gas exchanges heat with the heat exchange medium flowing in the second medium pipeline of the secondary heat exchange device, the liquid liquefied gas that is not flash evaporated absorbs heat and completely gasifies to form fourth gaseous liquefied gas, and the fourth gaseous liquefied gas is conveyed to the conveying main pipe through the output end of the second liquefied gas pipeline, and is conveyed to the combustion device after being converged with the first gaseous liquefied gas and the third gaseous liquefied gas.

[0044] Further technical solutions, when the first gaseous liquefied gas is conveyed to the conveying main pipe in step S3 and the third gaseous liquefied gas is conveyed to the conveying main pipe in step S41, further comprising: the pressure of the converged gas flow of the first gaseous liquefied gas and the third gaseous liquefied gas is stabilized through a first nozzle pressure expansion device, so that the pressure of the converged gas flow is maintained at 0.2-0.45 MPa; when the fourth gaseous liquefied gas is conveyed to the conveying main pipe in step S43, the pressure of the fourth gaseous liquefied gas is increased to 0.2-0.45 MPa through a second nozzle pressure expansion device, so that the pressure of all gaseous liquefied gas in the conveying main pipe is consistent before being conveyed to the combustion device; and before the gaseous liquefied gas is conveyed to the combustion device, the gaseous liquefied gas is first introduced into a gas storage tank connected in series between the conveying main pipe and the combustion device for temporary storage, and when the pressure in the gas storage tank exceeds 0.6-0.8 MPa, a pressure relief valve on the gas storage tank is automatically opened for pressure relief.

[0045] The working principle and beneficial effects of the technical solutions provided in the application are as follows:

[0046] Liquefied petroleum gas (LPG) is stored in a liquid state at 0.5~1.2 MPa in the storage device. After being discharged from the bottom, it is depressurized to 0.2~0.45 MPa by a first-stage pressure-reducing valve, achieving partial flash evaporation. The resulting gas-liquid mixture is separated into gaseous and liquid states in a separation device. The gaseous LPG is fed into the main pipe to ensure stable combustion in the combustion equipment, while the liquid LPG absorbs heat and vaporizes in a first-stage heat exchanger before flowing into the main pipe, realizing the utilization of cold energy. This device achieves partial flash evaporation by controlling the pressure reduction process. While utilizing the phase change heat absorption of LPG for refrigeration, it can ensure a stable gas supply to the combustion equipment, realizing the cascade utilization of energy. It is suitable for applications such as RVs and long-haul trucks. Attached Figure Description

[0047] Appendix Figure 1 This is a system structure diagram of Embodiment 1 of the present invention;

[0048] Appendix Figure 2 This is a cross-sectional view of the gas-liquid separation device in Embodiment 1 of the present invention;

[0049] Appendix Figure 3 This is a system structure diagram of Embodiment 2 of the present invention;

[0050] Appendix Figure 4 This is a cross-sectional view of the intermediate separator in Embodiment 2 of the present invention;

[0051] Appendix Figure 5 This is a cross-sectional view of the primary heat exchange device according to Embodiment 1 of the present invention;

[0052] Appendix Figure 6 This is a system structure diagram of Embodiment 3 of the present invention;

[0053] Appendix Figure 7 This is a system structure diagram of Embodiment 4 of the present invention;

[0054] Appendix Figure 8 This is a top view of the two-stage heat exchange device in Embodiment 4 of the present invention;

[0055] Appendix Figure 9 For the appendix Figure 8 Cross-sectional view of the secondary heat exchanger;

[0056] Appendix Figure 10 This is a system structure diagram of Embodiment 5 of the present invention;

[0057] In the above drawing: 1. liquefied gas storage device; 101. liquid outlet pipe; 2. first pressure reducing valve; 3. gas-liquid separation device; 31. first gas phase outlet; 32. first liquid phase outlet; 33. baffle; 4. primary heat exchange device; 41. first medium pipeline; 42. first liquefied gas pipeline; 43. first heat exchange structure; 431. aluminum fin; 5. delivery main pipe; 6. combustion equipment; 7. intermediate separator; 72. second gas phase outlet; 74. second liquid phase outlet; 8. second pressure reducing valve; 9. secondary heat exchange device; 91. second medium pipeline; 92. second liquefied gas pipeline; 93. second heat exchange structure; 10. first nozzle pressure recovery device; 11. second nozzle pressure recovery device; 12. gas storage tank. DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0059] As to the "first", "second", etc. used herein, they do not particularly mean the order or sequence, nor limit the present application, but are only used to distinguish the components or operations described by the same technical terms.

[0060] As to the "connection" or "positioning" used herein, it can mean that two or more components or devices directly contact each other or indirectly contact each other, or can mean that two or more components or devices operate or act on each other.

[0061] As to the "contain", "include", "have", etc. used herein, they are all open terms, that is, they mean containing but not limited to.

[0062] As to the words (terms) used herein, they generally have the usual meanings of each word used in this field, in the content of the present application, and in the special content, unless otherwise specifically noted. Some words used to describe the present application will be discussed below or elsewhere in the specification to provide additional guidance to those skilled in the art on the description of the present application.

[0063] As to the "front", "back", "up", "down", "left", "right", etc. used herein, they are all directional words, which are only used to illustrate the positional relationship between the structures in the present application, and are not used to limit the specific direction of the protection scheme and actual implementation of the present application. Embodiment one

[0064] The embodiment provides a liquefied gas cold energy utilization system, which is suitable for a motor home scene and can synchronously realize liquefied gas combustion power supply and refrigerator cold storage room refrigeration. Figure 1 As shown in the specific structure,

[0065] The liquefied gas storage device 1 can adopt a conventional household LPG steel cylinder with a volume of 15L, and is filled with liquefied petroleum gas with a filling amount of 8kg. The pressure control assembly of the steel cylinder is used to stabilize the internal pressure of the liquefied gas storage device 1 at 0.8MPa, and the pressure can ensure that the liquefied gas remains in a liquid state at room temperature of 25℃. The bottom of the liquefied gas storage device 1 is connected with a liquid outlet pipe 101, and a manual stop valve is arranged on the liquid outlet pipe 101 to control the output on-off of the liquid liquefied gas.

[0066] The first pressure reducing valve 2 adopts a pilot type pressure reducing valve, the input end of the first pressure reducing valve 2 is sealingly connected with the liquid outlet pipe 101 of the liquefied gas storage device 1 through an oil-resistant rubber pipe, and the output end is communicated with the input end of the gas-liquid separation device 3 through a stainless steel pipe. The pressure regulating range of the first pressure reducing valve 2 is set to 0.3MPa, and the pressure of the liquid liquefied gas output from the liquefied gas storage device 1 can be reduced from 0.8MPa to 0.3MPa during work. Under this pressure drop, part of the liquid liquefied gas will flash into a gaseous state due to the sudden pressure drop, forming a gas-liquid mixed flow. The proportion of the gaseous state after flashing is about 12%, and the proportion of the liquid state is about 88%. The temperature after flashing is reduced to about -14℃.

[0067] As shown in the specific structure, Figure 2 The gas-liquid separation device 3 is a horizontally placed cylindrical stainless steel container with a diameter of 200mm, a length of 600mm, a length-diameter ratio of 3 and a volume of about 18L. The input end of the gas-liquid separation device 3 is communicated with the output end of the first pressure reducing valve 2; a first gas phase outlet 31 is arranged at the top position of the gas-liquid separation device 3, and a first liquid phase outlet 32 is arranged at the bottom position.

[0068] By designing the gas-liquid separation device 3 as a horizontal container with a large length-diameter ratio, sufficient time can be ensured for the gas-liquid separation. In the embodiment, baffles 33 are further arranged at the top of the inner wall of the gas-liquid separation device 3, and the baffles 33 can be staggered in the horizontal direction to prolong the flow path of the gaseous liquefied gas, so that the liquid drops have sufficient time to drop, and the gas-liquid separation effect is ensured.

[0069] In the possible embodiment, a stainless steel liquid drop isolation net can also be arranged below the first gas phase outlet 31 to intercept the tiny liquid drops entrained in the gaseous state, so as to avoid the liquid liquefied gas entering the delivery main pipe 5.

[0070] The internal pressure of the gas-liquid separator 3 is the same as the output pressure of the first pressure reducing valve 2. During operation, the gaseous liquefied gas generated by flash evaporation accumulates at the top of the gas-liquid separator 3 and is output through the first gas phase outlet 31; the unflashed liquid liquefied gas accumulates in the bottom liquid accumulation area and is output to the first-stage heat exchanger 4 through the first liquid phase outlet 32.

[0071] Preferably, the outer wall of the gas-liquid separator 3 can also be wrapped with an insulation layer, such as glass wool rolls or polyurethane foam, to maintain the internal temperature, reduce cold energy loss, and improve the cold energy utilization efficiency in the subsequent primary heat exchange device 4. At the same time, the insulation layer can also prevent the liquid liquefied gas in the gas-liquid separator 3 from continuing to absorb heat and excessively vaporize.

[0072] The primary heat exchange device 4 can be integrated into the back of the refrigerator compartment, including a first medium pipeline 41, a first liquefied gas pipeline 42, and a first heat exchange structure 43.

[0073] The first medium pipeline 41 can be arranged in the evaporator area of ​​the refrigerator compartment. The heat exchange medium flowing inside is air. The air is driven by the refrigerator fan to flow through the first heat exchange structure 43 to achieve heat exchange.

[0074] The first liquefied gas pipeline 42 is a horizontally arranged, gradually expanding pipe bundle, the specific structure of which is as follows: Figure 5 As shown, the diameter d1 of the front end 42a is 10mm, the diameter d2 of the rear end 42b is 15mm, the input end pipe is connected to the first liquid phase outlet 32 ​​of the gas-liquid separator 3, and the output end is connected to the main conveying pipe 5.

[0075] The first heat exchange structure 43 includes aluminum fins 431 surrounding the outer wall of the first liquefied gas pipeline 42. The aluminum fins 431 can increase the heat exchange contact area and improve the heat transfer efficiency. During operation, the liquefied gas output from the gas-liquid separator 3 has a temperature of approximately -14°C and flows within the first liquefied gas pipeline 42, exchanging heat with the air in the first medium pipeline 41. After absorbing heat from the air, the liquefied gas gradually vaporizes to form gaseous liquefied gas; simultaneously, the air temperature decreases after heat exchange, achieving refrigeration of the cold storage compartment. The vaporized gaseous liquefied gas flows through the output end of the first liquefied gas pipeline 42 into the main delivery pipe 5.

[0076] One end of the main delivery pipe 5 is connected via a tee connector to the first gas phase outlet 31 of the gas-liquid separator 3 and the output end of the first liquefied gas pipeline 42 of the first-stage heat exchanger 4, respectively, and the other end is connected to the air inlet of the combustion device 6. The function of the main delivery pipe 5 is to merge the two gaseous liquefied gas streams, form a stable gaseous flow after merging, and then deliver it to the combustion device 6.

[0077] In this embodiment, the combustion device 6 is a gas stove installed in the RV. The combustion device 6 can also be a gas water heater, gas furnace, etc.

[0078] The operation process of the embodiment is as follows:

[0079] The manual stop valve at the bottom of the liquefied gas storage device 1 is opened, and the liquid liquefied gas enters the first pressure reducing valve 2 through the liquid outlet pipe 101; the first pressure reducing valve 2 reduces the pressure of the liquefied gas to 0.3 MPa, and part of the liquefied gas is flashed into a gaseous state, and the gas-liquid mixture enters the gas-liquid separation device 3; the gas-liquid separation device 3 separates the gaseous state into the first gas phase outlet 31 of the gas phase outlet 31, and the liquid state enters the first liquid phase outlet 32 of the first liquid phase outlet 32 into the first heat exchange device 4; in the first heat exchange device 4, the liquid liquefied gas is gasified by absorbing heat and flows into the delivery main pipe 5, and at the same time, the refrigerator cold storage room is cooled; the delivery main pipe 5 converges two routes of gaseous liquefied gas, and stably delivers to the combustion equipment 6 for combustion.

[0080] The liquefied gas cold energy utilization system provided in the embodiment is suitable for a scene where the amount of liquefied gas used is not high, for example, can be arranged in the liquefied gas system of a motor home, and by fully utilizing the cold energy of the liquefied gas, the refrigerator can be cooled and fuel for the gas stove can be provided at the same time. Embodiment two

[0081] As shown in Figure 2 , 3 and Figure 4 , the intermediate separator 7 is added in the embodiment, the output end of the first liquefied gas pipeline 42 is connected with the input end 71 of the intermediate separator 7, the intermediate separator 7 is provided with a second gas phase outlet 72, the second gas phase outlet 72 is connected to the delivery main pipe 5, and the gas-liquid liquefied gas output by the first liquefied gas pipeline 42 is delivered to the delivery main pipe 5 through the second gas phase outlet 72 of the intermediate separator 7.

[0082] The intermediate separator 7 plays a role of buffering and further separating. When the flow of liquefied gas is large, the first heat exchange device 4 may not be able to gasify all the liquid liquefied gas, and therefore the intermediate separator 7 is arranged to separate the liquid and gaseous liquefied gas, so that only the gaseous liquefied gas enters the delivery main pipe 5. In addition, when the flow of liquefied gas fluctuates greatly, such as when the storage device instantaneously increases the amount of liquid supply, the intermediate separator 7 can temporarily store part of the gas-liquid mixture, so as to avoid the high-speed gas-liquid flow directly impacting the delivery main pipe 5, and to maintain the stability of the pressure in the main pipe.

[0083] As shown in Figure 4 , the intermediate separator 7 is a vertically placed cylindrical container, the input end 71 is connected along the tangent direction of the middle part of the container, so that the gas-liquid mixture output by the first heat exchange device 4 spirally flows along the wall of the container, and the centrifugal separation effect is realized. The container top is provided with a second gas phase outlet 72, and the second gas phase outlet 72 is communicated with the delivery main pipe 5. In the embodiment, the intermediate separator 7 simultaneously plays a role of gas-liquid separation and temporary storage of a small amount of liquid liquefied gas, and the liquid liquefied gas remaining in the intermediate separator 7 will be slowly gasified by absorbing heat, and then enter the delivery main pipe 5.

[0084] Preferably, a droplet isolation net 73 can be arranged at the top of the intermediate separator 7 to block the suspension droplets. In addition, a liquid discharge port can also be reserved at the bottom, which is normally closed and only used during maintenance. Embodiment Three

[0085] As shown in Figure 6 , the embodiment provides a liquefied gas cold energy utilization system with an intermediate separator 7 and two-stage heat exchange. The system optimizes the structure of the intermediate separator 7 based on Embodiment Two and adds a second pressure reducing valve 8 and a two-stage heat exchange device 9, which is suitable for scenarios where the gas consumption of the combustion equipment 6 is large and stable, such as long-distance trucks using liquefied gas as a power source, which use an engine as the combustion equipment 6 and need to continuously burn liquefied gas. In this scenario, the continuous use of liquefied gas is large, and the staged pressure reduction refrigeration by the first heat exchange device 4 and the second heat exchange device 9 can fully utilize the cold energy of the liquefied gas.

[0086] Referring to Figure 4 , in this embodiment, the container bottom of the intermediate separator 7 is provided with a second liquid phase outlet 74, and a manual stop valve is arranged at the second liquid phase outlet 74, which is kept open during normal operation. In a possible embodiment, an electric valve can be arranged at the second liquid phase outlet 74, and the electric valve determines whether to open according to the ambient temperature monitored by the temperature sensor in the first refrigeration device. When the ambient temperature is high and the first refrigeration device needs a large amount of heat absorption, the first heat exchange device 4 can vaporize all the liquefied gas, so the electric valve does not need to be opened. When the ambient temperature is low and the first refrigeration device operates at low power, a large amount of liquefied gas in the first heat exchange device 4 is not vaporized, and the electric valve can be opened to start the second heat exchange device 9. In another possible embodiment, the opening degree of the electric valve can also be determined comprehensively according to the ambient temperature monitored by the temperature sensor in the second refrigeration device and the ambient temperature monitored by the temperature sensor in the first refrigeration device. For example, when the ambient temperature monitored by the temperature sensor in the second refrigeration device is lower than a set threshold, the electric valve is controlled to open by 50%, and when the ambient temperature monitored by the temperature sensor in the second refrigeration device is higher than the set threshold, the electric valve is controlled to open by 100%.

[0087] The outer wall of the intermediate separator 7 is wrapped with a thermal insulation layer to reduce the loss of cold energy in the intermediate separator and avoid excessive vaporization of the internal liquid liquefied gas.

[0088] The second pressure reducing valve 8 in this embodiment adopts a pilot operated pressure reducing valve, the input end of which is sealingly connected with the second liquid phase outlet 74 of the intermediate separator 7, and the output end of which is in communication with the input end of the second liquefied gas pipeline 92 of the two-stage heat exchange device 9.

[0089] The second pressure reducing valve 8 can reduce the pressure of the liquid liquefied gas output from the second liquid phase outlet 74 of the intermediate separator 7 from 0.3 MPa to 0.15 MPa. At this pressure drop, part of the liquid liquefied gas will flash into gas, forming a gas-liquid mixed flow. The temperature of the flashed gas-liquid mixed flow is about -30℃.

[0090] The secondary heat exchange device 9 can be integrated into the air conditioner to realize the functions of refrigeration or dehumidification. The secondary heat exchange device 9 includes a second medium pipeline 91, a second liquefied gas pipeline 92, and a second heat exchange structure 93. The heat exchange medium flowing in the second medium pipeline 91 is air. The air is driven by the built-in fan of the air conditioner to flow through the second heat exchange structure 93 to realize heat exchange.

[0091] As shown in Figure 9 , the second liquefied gas pipeline 92 includes three branch pipes. The input end 92a of the three branch pipes is connected to the output end of the second pressure reducing valve 8, and the output end 92b is connected to the delivery main pipe 5. The ratio of the pipe diameter of the output end 92b to the input end 92a of the second liquefied gas pipeline 92 is 2.5:1. The expansion of the pipe diameter ensures the stability of the pressure and flow rate in the second liquefied gas pipeline 92, and prevents the pressure in the pipe from suddenly increasing due to gasification.

[0092] As shown in Figure 8 , the second heat exchange structure 93 is composed of a heat exchange plate 93a and a corrugated fin 93b. The heat exchange plate 93a can be an aluminum alloy plate, and the corrugated fin 93b can be an aluminum alloy fin. Multiple corrugated fins 93b are parallelly attached to the upper and lower surfaces of the heat exchange plate 93a and are fixed by welding. Three branch pipes pass through the inside of the heat exchange plate 93a and are brazed and sealed with the heat exchange plate, forming a continuous flow channel to ensure that the liquefied gas in the branch pipes can fully contact the heat exchange plate 93a.

[0093] During operation, the gas-liquid mixture output by the primary heat exchange device 4 enters the intermediate separator 7. The gaseous liquefied gas is collected at the top under the action of centrifugal force and gravity, enters the delivery main pipe 5 through the second gas phase outlet 72, and the liquid liquefied gas is collected at the bottom, flows into the second pressure reducing valve 8 through the second liquid phase outlet 74.

[0094] After being reduced in pressure by the second pressure reducing valve 8, part of the liquid liquefied gas flashes into gas. The gas-liquid mixed flow enters the second liquefied gas pipeline 92 of the secondary heat exchange device 9. The gas-liquid mixed flow in the branch pipes exchanges heat with the air in the second medium pipeline 91. The liquid liquefied gas gradually completely gasifies after absorbing the heat of the air. The gaseous liquefied gas after gasification converges at the output end and enters the delivery main pipe 5. After being combined with the gaseous liquefied gas from the gas-liquid separation device 3 and the gaseous liquefied gas from the intermediate separator 7, it is delivered to the combustion equipment 6 for combustion.

[0095] By setting the second pressure reducing valve 8 and the two-stage heat exchange device 9, the non-gasified liquid liquefied gas in the intermediate separator 7 can be subjected to a second partial flash evaporation and heat exchange gasification, the non-gasified liquefied gas is fully utilized, and the large gas demand of the combustion equipment 6 is met; at the same time, the combination design of the multiple branch pipes and the corrugated fins in the two-stage heat exchange device 9 expands the contact area of the liquefied gas and the heat exchange medium, ensures that the liquefied gas is fully heat-exchanged and gasified, and avoids the entry of the liquid liquefied gas into the delivery main pipe.

[0096] The liquefied gas cold energy utilization system provided in the embodiment is suitable for long-distance freight trucks using liquefied gas as fuel. The engine of such a truck consumes liquefied gas continuously, and therefore is very suitable for using the system to fully utilize the cold energy, thereby providing refrigeration for the vehicle cabin air conditioner, vehicle-mounted refrigerator and other equipment. Embodiment Four

[0097] As shown in Figure 7 Compared with embodiment three, the first nozzle diffuser 10 and the second nozzle diffuser 11 are added in the embodiment to be suitable for the scene where the delivery pipeline path is long.

[0098] The first nozzle diffuser 10 is connected to the intersection of the first gaseous outlet of the gas-liquid separation device 3, the second gaseous outlet 72 of the intermediate separator 7 and the delivery main pipe 5, and is used to stabilize the pressure of the multiple gaseous media after merging. The gaseous liquefied gas output by the gas-liquid separation device 3 is subjected to pressure reduction flash evaporation, and the pressure is reduced to 0.2-0.45 MPa. The pressure of the second gaseous outlet 72 of the intermediate separator 7 is also maintained in the interval of 0.2-0.45 MPa. After the two streams of gaseous liquefied gas are combined, the first nozzle diffuser 10 expands the pressure to 0.5-1.2 MPa through the conical pipe structure to meet the delivery requirements of the long-path delivery main pipe 5.

[0099] The second nozzle diffuser 11 is connected to the intersection of the second liquefied gas pipeline 92 output end of the two-stage heat exchange device 9 and the delivery main pipe 5, and is used to increase the pressure of the gaseous liquefied gas after the two-stage heat exchange to the main pipe adaptation pressure. The gaseous liquefied gas output by the two-stage heat exchange device 9 is subjected to flash evaporation and heat absorption, and the pressure is reduced to 0.1-0.2 MPa. The second nozzle diffuser 11 can pressurize the gaseous liquefied gas and input it into the main pipe, and also can prevent the gaseous medium in the main pipe from flowing back into the two-stage heat exchange device 9.

[0100] By setting the first nozzle diffuser 10 and the second nozzle diffuser 11, the pressure of the region after the first pressure reduction flash evaporation and the region after the second pressure reduction flash evaporation can be partitioned, the pressure in each region is stabilized, and the pressure in the main pipe is also increased to ensure that the pressure of the liquefied gas after the pressure reduction flash evaporation meets the delivery requirements.

[0101] The pressure and temperature of each part of the system are shown in the following table:

[0102] Example Five

[0103] As shown in the figure, this embodiment adds a gas tank 12 in series between the delivery main pipe 5 and the combustion equipment 6 on the basis of Example Four. Figure 10 A relief valve interface is welded on the top of the gas tank 12, and a spring relief valve 13 is installed at the interface, with the opening pressure of the relief valve 13 set to 0.7 MPa. When the pressure in the gas tank 12 exceeds 0.7 MPa due to abnormal conditions (such as sudden shutdown of the combustion equipment 6 or failure of the main pipe valve), the relief valve 13 will automatically open to release pressure, and will automatically close when the pressure drops to below 0.6 MPa, ensuring the safe use of the gas tank 12.

[0104] By setting the gas tank 12, the pressure and flow of gaseous liquefied gas entering the combustion equipment 6 can be ensured to be stable and continuous, avoiding problems such as large and small combustion flames and flameout caused by gas fluctuations, and ensuring the stability of the operation of the combustion equipment 6. In addition, the gas tank 12 can also mix the liquefied gas uniformly. Since the saturated vapor pressure of propane is higher than that of butane, the gas flashed out for the first time is mainly propane, and the gas output by the primary heat exchange device 4 and the secondary heat exchange device 9 has gradually increasing butane. After entering the gas tank, the various gases can be fully mixed and uniform, which is conducive to full combustion.

[0105] Example Six Corresponding to the system in Example One, a liquefied gas cold energy utilization method is provided in this embodiment, comprising the following steps:

[0106] S1: liquefied gas storage, storing liquefied gas in a liquefied gas storage device 1 with an internal pressure maintained at 0.5-1.2 MPa, and the bottom of the liquefied gas storage device 1 is provided with a liquid outlet;

[0107] S2: primary pressure reduction and flashing, reducing the pressure of the liquid liquefied gas output from the liquid outlet of the liquefied gas storage device 1 to 0.2-0.45 MPa through the first pressure reduction valve 2, to cause part of the liquid liquefied gas to flash into gas;

[0108] S3: primary gas-liquid separation, introducing the gas-liquid mixed liquefied gas treated in step S2 into a gas-liquid separation device 3 to obtain first gaseous liquefied gas and first liquid liquefied gas, and the first gaseous liquefied gas is delivered to the delivery main pipe through the first gas phase outlet 31 of the gas-liquid separation device 3;

[0109]

[0110] ​S4: first heat exchange for cooling, the first liquid liquefied gas separated in step S3 is introduced into the first liquefied gas pipeline 42 of the first heat exchange device 4, so that the first liquid liquefied gas exchanges heat with the heat exchange medium flowing in the first medium pipeline 41 of the first heat exchange device 4, and the first liquid liquefied gas is gasified to form second gaseous liquefied gas after absorbing heat, and the second gaseous liquefied gas is transported to the delivery main pipe 5 through the output end of the first liquefied gas pipeline 42;

[0111] S5: gaseous delivery and combustion, the first gaseous liquefied gas in step S3 and the second gaseous liquefied gas in step S4 are combined through the delivery main pipe 5, and the combined gaseous liquefied gas is delivered to the combustion device 6 for combustion. Example Seven

[0112] Corresponding to the system in example three, the embodiment provides a liquefied gas cold energy utilization method, which is based on example six, and further comprises the following steps between step S4 and step S5:

[0113] S41: intermediate separation, the second gaseous liquefied gas (containing residual liquid liquefied gas which is not completely gasified) output from the first liquefied gas pipeline 42 in step S4 is introduced into the intermediate separator 7, and third gaseous liquefied gas and second liquid liquefied gas are separated, and the third gaseous liquefied gas is delivered to the delivery main pipe 5 through the second gas phase outlet 72 of the intermediate separator 7;

[0114] S42: second-stage pressure reduction flash evaporation, the second liquid liquefied gas separated in step S41 is reduced to 0.1-0.2 MPa in pressure through the second pressure reduction valve, so as to promote part of the second liquid liquefied gas to be flash evaporated into gaseous state;

[0115] S43: second heat exchange for cooling, the gas-liquid mixed liquefied gas treated in step S42 is introduced into the second liquefied gas pipeline 92 of the second heat exchange device 9, so that the gas-liquid mixed liquefied gas exchanges heat with the heat exchange medium flowing in the second medium pipeline 91 of the second heat exchange device 9, the liquid liquefied gas which is not flash evaporated is completely gasified to form fourth gaseous liquefied gas after absorbing heat, and the fourth gaseous liquefied gas is delivered to the delivery main pipe 5 through the output end of the second liquefied gas pipeline 92, and is combined with the first gaseous liquefied gas and the third gaseous liquefied gas to be delivered to the combustion device 6. Example Eight

[0116] Corresponding to the system in embodiment four, the embodiment provides a liquefied gas cold energy utilization method, which is based on embodiment seven, and when the first gaseous liquefied gas is delivered to the delivery header 5 in step S3, and the third gaseous liquefied gas is delivered to the delivery header 5 in step S41, the method further comprises: the pressure of the combined gas flow of the first gaseous liquefied gas and the third gaseous liquefied gas is stabilized by the first nozzle diffuser 10, so that the pressure of the combined gas flow is maintained at 0.2-0.45 MPa; when the fourth gaseous liquefied gas is delivered to the delivery header 5 in step S43, the pressure of the fourth gaseous liquefied gas is raised to 0.2-0.45 MPa by the second nozzle diffuser 11, and after ensuring that the pressures of all gaseous liquefied gases in the delivery header 5 are consistent, the gaseous liquefied gases are delivered to the combustion equipment 6; and before the gaseous liquefied gases are delivered to the combustion equipment 6, the gaseous liquefied gases are first introduced into the gas storage tank 12 connected in series between the delivery header 5 and the combustion equipment 6 for temporary storage, and when the pressure in the gas storage tank 12 exceeds 0.6-0.8 MPa, the pressure relief valve on the gas storage tank 12 automatically opens to release pressure.

[0117] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A liquefied gas cold energy utilization system, characterized by, The application relates to a liquefied gas cold energy utilization system, which comprises the following parts: a liquefied gas storage device with an internal pressure of 0.5-1.2 MPa, wherein the bottom of the liquefied gas storage device is provided with a liquid outlet; a first pressure reducing valve, the input end of which is connected with the liquid outlet of the liquefied gas storage device, and which is used for reducing the pressure of the liquefied gas to 0.2-0.45 MPa and making part of the liquefied gas flash into a gaseous state; a gas-liquid separation device, the input end of which is connected with the output end of the first pressure reducing valve, wherein the gas-liquid separation device is provided with a first gas phase outlet and a first liquid phase outlet, the first gas phase outlet is connected with a delivery main pipe, and the first liquid phase outlet is connected with a primary heat exchange device; a primary heat exchange device, which comprises a first medium pipeline for flowing through a heat exchange medium and a first liquefied gas pipeline for flowing through liquefied gas, wherein the first medium pipeline and the first liquefied gas pipeline are provided with a first heat exchange structure, the input end of the first liquefied gas pipeline is connected with the first liquid phase outlet of the gas-liquid separation device, the output end of the first liquefied gas pipeline is communicated with the delivery main pipe, and the first medium pipeline is connected with a first refrigeration equipment; a delivery main pipe, one end of which is connected with the first gas phase outlet of the gas-liquid separation device, and the other end of which is connected with a combustion equipment, wherein the delivery main pipe is used for combining the gaseous liquefied gas output by the gas-liquid separation device and the gaseous liquefied gas output by the primary heat exchange device, and then delivering the combined gaseous liquefied gas to the combustion equipment; an intermediate separator, the output end of the first liquefied gas pipeline is connected with the input end of the intermediate separator, the intermediate separator is provided with a second gas phase outlet, the second gas phase outlet is connected with the delivery main pipe, and the gaseous liquefied gas output by the first liquefied gas pipeline is subjected to gas-liquid separation through the intermediate separator, and then is output from the second gas phase outlet to the delivery main pipe; the intermediate separator further comprises a second liquid phase outlet, the second liquid phase outlet is arranged at the bottom of the intermediate separator, the outer wall of the intermediate separator is wrapped with a heat preservation layer, and the liquefied gas cold energy utilization system further comprises: a second pressure reducing valve, the input end of which is connected with the second liquid phase outlet of the intermediate separator, and which is used for reducing the pressure of the liquefied gas to 0.1-0.2 MPa and making part of the liquefied gas flash into a gaseous state; a secondary heat exchange device, which comprises a second medium pipeline for flowing through a heat exchange medium and a second liquefied gas pipeline for flowing through liquefied gas, wherein the second medium pipeline and the second liquefied gas pipeline are provided with a second heat exchange structure, the input end of the second liquefied gas pipeline is connected with the output end of the second pressure reducing valve, the output end of the second liquefied gas pipeline is connected with the delivery main pipe, and the second medium pipeline is connected with a second refrigeration equipment.

2. The liquefied gas cold energy utilization system according to claim 1, characterized by The gas-liquid separation device is a horizontally placed cylindrical structure, the first gas phase outlet is arranged at the top of the gas-liquid separation device, the first liquid phase outlet is arranged at the bottom of the gas-liquid separation device, a liquid droplet isolation net is arranged below the first gas phase outlet, and the outer wall of the gas-liquid separation device is provided with a heat preservation layer.

3. The liquefied gas cold energy utilization system according to claim 1, characterized by The first liquefied gas pipeline of the primary heat exchange device is a horizontally arranged tube bundle with gradually increasing diameters, the ratio of the diameters of the rear end and the front end of the first liquefied gas pipeline is 1.5:1-2.5:1, and the first heat exchange structure is an aluminum fin wrapped outside the first liquefied gas pipeline.

4. The liquefied gas cold energy utilization system according to claim 1, characterized by The intermediate separator is a vertically placed cylindrical structure, the second gas phase outlet is arranged at the top of the intermediate separator, the input end of the first liquefied gas pipeline is arranged at the middle of the intermediate separator in a tangential direction, and a liquid droplet isolation net is arranged below the second gas phase outlet.

5. The liquefied gas cold energy utilization system according to claim 1, characterized by The second liquefied gas pipeline comprises a plurality of branch pipes, the second heat exchange structure comprises heat exchange plates and corrugated fins, the corrugated fins are attached to the upper and lower surfaces of the heat exchange plates, the plurality of branch pipes pass through the inside of the heat exchange plates, the input ends of the plurality of branch pipes are connected to the output end of the second pressure reducing valve, the output ends of the plurality of branch pipes are connected to a delivery main pipe after being connected, and the ratio of the rear end diameter to the front end diameter of the second liquefied gas pipeline is 2:1-3:

1.

6. The liquefied gas cold energy utilization system according to claim 1, characterized by Further comprising: A first nozzle pressure expansion device connected to the intersection of the first gas phase outlet of the gas-liquid separation device, the second gas phase outlet of the intermediate separator, and the delivery main pipe, for stabilizing the pressure of the plurality of gaseous media after merging; A second nozzle pressure expansion device connected to the intersection of the output end of the second liquefied gas pipeline of the secondary heat exchange device and the delivery main pipe, for increasing the pressure of the gaseous liquefied gas after secondary heat exchange to be adapted to the delivery main pipe.

7. A method for utilizing cold energy of liquefied gas, characterized by, The method is realized by the liquefied gas cold energy utilization system in any one of claims 1-6, and comprises the following steps: S1: liquefied gas storage, storing liquefied gas in a liquefied gas storage device, and maintaining the internal pressure at 0.5-1.2 MPa; S2: primary pressure reduction flash evaporation, reducing the pressure of the liquid liquefied gas output from the liquid outlet of the liquefied gas storage device to 0.2-0.45 MPa through a first pressure reducing valve, so that part of the liquid liquefied gas is flashed into a gaseous state; S3: primary gas-liquid separation, introducing the gas-liquid mixed liquefied gas treated in step S2 into a gas-liquid separation device to obtain first gaseous liquefied gas and first liquid liquefied gas, wherein the first gaseous liquefied gas is delivered to a delivery main pipe through a first gas phase outlet of the gas-liquid separation device; S4: primary heat exchange refrigeration, introducing the first liquid liquefied gas obtained in step S3 into a first liquefied gas pipeline of a primary heat exchange device, so that the first liquid liquefied gas exchanges heat with a heat exchange medium flowing in a first medium pipeline of the primary heat exchange device, the first liquid liquefied gas gasifies to form second gaseous liquefied gas after absorbing heat, the second gaseous liquefied gas contains residual liquid liquefied gas that has not completely gasified, and the second gaseous liquefied gas is delivered to an intermediate separator through an output end of the first liquefied gas pipeline; S41: intermediate separation, introducing the second gaseous liquefied gas output by the first liquefied gas pipeline in step S4 into the intermediate separator to obtain third gaseous liquefied gas and second liquid liquefied gas, and delivering the third gaseous liquefied gas to the delivery main pipe through a second gas phase outlet of the intermediate separator; S42: two-stage pressure reduction flash evaporation, the pressure of the second liquid liquefied gas separated in step S41 is reduced to 0.1-0.2 MPa by a second pressure reduction valve, so as to cause part of the second liquid liquefied gas to flash evaporate into a gaseous state; S43: two-stage heat exchange refrigeration, the gas-liquid mixed liquefied gas treated in step S42 is introduced into a second liquefied gas pipeline of a two-stage heat exchange device, so that the gas-liquid mixed liquefied gas exchanges heat with a heat exchange medium flowing in a second medium pipeline of the two-stage heat exchange device, the unflash-evaporated liquid liquefied gas is completely gasified into fourth gaseous liquefied gas after absorbing heat, and the fourth gaseous liquefied gas is transported to the delivery main pipe through the second liquefied gas pipeline and is combined with the first gaseous liquefied gas and the third gaseous liquefied gas; S5: gaseous delivery combustion, the combined gaseous liquefied gas is delivered to a combustion device by the delivery main pipe for combustion.

Images