Micro-channel heat exchanger for natural gas liquefaction

Abstract

The application discloses a micro channel heat exchanger for liquefying natural gas, and relates to the technical field of natural gas processing. The micro channel heat exchanger comprises a shell, heat exchange plates and a disturbance sleeve. The heat exchanger is optimized in heat exchange structure and flow channel design, adopts countercurrent heat exchange, rectangular gas phase channels, narrow slit-shaped gas-liquid channels and elliptical liquid phase channels, is combined with a high-thermal-conductivity layer and a hydrophobic corrosion-resistant coating, effectively improves heat transfer rate, reduces pressure drop and thermal resistance, improves gas-liquid phase change efficiency, sets a hierarchical disturbance mechanism, integrates a memory alloy sleeve and an elastic sleeve in the gas-liquid two-phase channel and the liquid phase channel, realizes first-order deformation disturbance and second-order high-frequency vibration disturbance by utilizing temperature response, timely breaks liquid film accumulation and eliminates flow dead zones, prevents icing and waxing, improves device operation stability, significantly enhances anti-interference ability and self-cleaning function, prolongs the continuous operation cycle of equipment, reduces the maintenance frequency, and realizes the heat exchange performance of high efficiency, stability and low failure.

Description

Technical Field

[0001] This invention relates to the field of natural gas processing technology, and more specifically, to a microchannel heat exchanger for natural gas liquefaction. Background Technology

[0002] Against the backdrop of energy structure transformation, natural gas, as a clean and efficient fossil fuel, is playing an increasingly prominent role in the global energy system. Natural gas is mainly composed of methane, which is gaseous at normal temperature and pressure and has a low volumetric energy density, making it unsuitable for long-distance transportation and large-scale storage. To address this issue, natural gas liquefaction technology has emerged, which cools natural gas and converts it into a liquid (LNG), reducing its volume by approximately 600 times, greatly improving transportation efficiency and economy. The liquefaction process is the core of a natural gas liquefaction plant, in which the heat exchanger in the refrigeration cycle system undertakes the critical heat exchange task, and its performance directly determines the efficiency, energy consumption, and equipment compactness of the entire liquefaction process.

[0003] Microchannel heat exchangers, as an important research direction in the field of thermal engineering in recent years, have gradually shown great potential in cryogenic engineering such as natural gas liquefaction due to their unique structural advantages. These heat exchangers typically refer to compact heat exchange devices with channel hydraulic diameters ranging from micrometers to millimeters. Their internal flow channel dimensions are much smaller than those of traditional shell-and-tube or plate-fin heat exchangers. Due to the significant reduction in channel size, a thinner thermal boundary layer can be formed when the fluid flows within it, significantly enhancing the convective heat transfer effect. At the same time, the fluid's stagnant volume and flow resistance are greatly reduced. Microchannel heat exchangers have extremely high heat transfer area per unit volume, which can be 5 to 10 times that of traditional heat exchangers. They can achieve efficient heat transfer in a very small space, meeting the urgent needs of modern liquefaction plants for equipment compactness and lightweight design.

[0004] In practical applications, existing microchannel heat exchangers for natural gas liquefaction mostly employ homogenized flow channel designs. During operation, they need to address the flow and heat transfer requirements at different stages, including gas cooling, gas-liquid phase change, and liquid subcooling. The homogenized flow channels cannot respond to changes in the internal fluid state and lack targeted optimization for the heat transfer characteristics of different phase regions. This leads to the formation of thick liquid films in the gas-liquid phase change zone and the generation of dead zones and temperature stratification in the liquid zone, resulting in decreased heat exchange efficiency and operational instability. This severely restricts further improvements in heat exchange performance. Therefore, to address these technical problems, it is necessary to provide a microchannel heat exchanger for natural gas liquefaction. Summary of the Invention

[0005] The purpose of this invention is to provide a microchannel heat exchanger for natural gas liquefaction to solve the above-mentioned problems.

[0006] To achieve the above objectives, an embodiment of the present invention provides the following technical solution:

[0007] A microchannel heat exchanger for natural gas liquefaction includes a shell, a heat exchange plate, and a disturbance sleeve. A natural gas inlet pipe and a natural gas outlet pipe are symmetrically embedded and fixed within the inner cavity of one side of the shell. One end of each of the natural gas inlet and outlet pipes is connected to a natural gas collecting inlet pipe and a natural gas collecting outlet pipe, respectively. A condensate inlet pipe and a condensate outlet pipe are symmetrically embedded and fixed within the inner cavity of the other side of the shell. One end of each of the condensate inlet and outlet pipes is connected to a condensate collecting inlet pipe and a condensate collecting outlet pipe, respectively. The heat exchange plate includes multiple microchannels formed within its inner cavity. A gas phase channel is formed in the upper part of the inner cavity of the heat exchange plate, and a gas phase channel is formed in the middle of the inner cavity of the heat exchange plate. The system includes a liquid two-phase channel, a liquid phase channel in the lower part of the heat exchange plate cavity, a high thermal conductivity layer fixed in the gas phase channel cavity, a corrosion-resistant layer fixed in the gas-liquid two-phase channel cavity, a high-strength impact-resistant layer fixedly connected in the liquid phase channel cavity, multiple heat exchange plates with a cooling plate fixed between adjacent plates, and a disturbance sleeve comprising multiple shape memory alloy sleeves uniformly fixedly connected in the gas-liquid two-phase channel and the liquid phase channel cavity. An elastic sleeve is fixedly connected to the inner wall of the shape memory alloy sleeve, and an expansion medium is filled between the shape memory alloy sleeve and the elastic sleeve. Multiple holes are formed on the outer surface of the elastic sleeve, and an elastic film is fixed in the cavity of the holes.

[0008] As a further improvement of the present invention, a plurality of L-shaped support feet are uniformly fixedly connected to the lower surface of the outer shell, and the outer shell is a rectangular sleeve with a hollow interior.

[0009] As a further improvement of the present invention, the outer surfaces of the natural gas inlet pipe and the natural gas outlet pipe are uniformly connected with a plurality of branch pipes one and two, respectively. The lower end of the branch pipe is fixedly connected to the upper surface of the heat exchange plate and is connected to the gas phase channel through a micro-channel. The upper end of the branch pipe two is fixedly connected to the lower surface of the heat exchange plate and is connected to the liquid phase channel through a micro-channel.

[0010] As a further improvement of the present invention, the outer surfaces of the condensate inlet pipe and the condensate outlet pipe are uniformly connected to a plurality of branch pipes three and four, respectively. The upper end of the branch pipe three is fixedly connected to and connected to the refrigeration plate, and the lower end of the branch pipe four is fixedly connected to and connected to the refrigeration plate.

[0011] As a further improvement of the present invention, the natural gas inlet pipe is located in the upper part of the inner cavity of the outer shell, the natural gas outlet pipe is located in the lower part of the inner cavity of the outer shell, the refrigerant inlet pipe is located in the lower part of the inner cavity of the outer shell, and the refrigerant outlet pipe is located in the upper part of the inner cavity of the outer shell.

[0012] As a further improvement of the present invention, the gas phase channel and the gas-liquid two-phase channel are connected by a micro-channel, and the gas-liquid two-phase channel and the liquid phase channel are connected by a micro-channel.

[0013] As a further improvement of the present invention, the gas phase channel is a hollow rectangular sleeve shape, and multiple longitudinal protrusions are uniformly fixedly connected to the inner wall of the gas phase channel. The corrosion-resistant layer is a narrow slit shape with semi-circular upper and lower ends, and the high-strength impact-resistant layer is elliptical.

[0014] As a further improvement of the present invention, there are multiple heat exchange plates and cooling plates, the outer surfaces of the heat exchange plates and cooling plates have the same shape and size, the heat exchange plates and cooling plates are arranged alternately and welded together.

[0015] As a further improvement of the present invention, the shape memory alloy sleeves are multiple and evenly distributed on the inner walls of the gas-liquid two-phase channel and the liquid phase channel. The shape memory alloy sleeves located on the inner wall of the gas-liquid two-phase channel have the same shape as the gas-liquid two-phase channel, and the shape memory alloy sleeves located on the inner wall of the liquid phase channel have the same shape as the liquid phase channel.

[0016] As a further improvement of the present invention, the heat exchange plate is composed of a thin metal plate one and a thin metal plate two spliced ​​together, and the thin metal plate one and the thin metal plate two are welded together to form a whole rectangular plate.

[0017] Compared with the prior art, the advantages of this invention are:

[0018] (1) This scheme improves the heat exchange efficiency of the device by optimizing the heat exchange structure and flow channel design. It adopts a counter-current heat exchange design, which allows the condenser and natural gas to flow in opposite directions. Under the same heat exchange area, the highest heat transfer rate is achieved, and the temperature difference distribution is more uniform and the wall temperature gradient is gentle, which effectively avoids local overcooling or overheating. At the same time, it maximizes the temperature difference between the hot and cold fluids. The gas phase channel is designed with a rectangular structure, which increases the flow diameter to reduce the pressure drop and expands the heat exchange surface area. With the high thermal conductivity layer, it can quickly receive and transfer the cold energy transferred by the cooling plate. The longitudinal convexity of the inner wall of the channel The fins also enhance gas turbulence, strengthening disturbances without affecting heat transfer. The gas-liquid two-phase channel adopts a narrow slit-shaped cross-section (semi-circular at both ends) to further increase the contact area between the gas-liquid mixture and the channel wall. The hydrophobic coating and corrosion-resistant layer work together to reduce liquid film adhesion and reduce liquid film thickness, significantly reducing thermal resistance and accelerating the gas-liquid phase change process. The elliptical liquid phase channel reduces the flow resistance of liquefied natural gas, facilitates smooth liquid flow, prevents flow dead zones, and the high-strength impact-resistant layer resists the flow impact of liquefied natural gas, improving the overall heat exchange efficiency.

[0019] (2) Through the graded disturbance mechanism and targeted flow channel optimization, the device’s anti-interference and fault prevention capabilities are significantly enhanced. When the liquid film in the gas-liquid two-phase channel is too thick, causing the wall temperature to rise, the shape memory alloy sleeve senses the temperature change and undergoes a phase change, changing from a circular tube of equal diameter to an inward arc-shaped bulge, changing the flow rate of the gas-liquid mixture and forming a first-level disturbance. If the temperature continues to be abnormal, the heat is transferred to the elastic sleeve, causing the expansion medium inside the sleeve to absorb heat, vaporize and expand, pushing the elastic film to bulge and form an arc-shaped bulge, generating a second-level high-frequency vibration disturbance, which completely breaks the liquid film.

[0020] (3) This scheme uses a shape memory alloy sleeve to sense the temperature change in the liquid phase channel and change the phase, from a circular tube of equal diameter to an inward arc-shaped protrusion, changing the flow rate of liquid natural gas and forming a primary disturbance. If the temperature continues to be abnormal, the heat is transferred to the elastic sleeve, causing the expansion medium inside the sleeve to absorb heat and vaporize and expand, pushing the elastic film to bulge and form an arc-shaped protrusion, generating a secondary high-frequency vibration disturbance, breaking the dead zone, preventing icing or waxing, and the elliptical channel reduces the flow resistance and the conical outlet guides the fluid to flow in a concentrated manner, further reducing the potential for failure, extending the continuous operation cycle, and reducing the frequency of shutdown cleaning. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a side view of the overall structure of the present invention;

[0023] Figure 3 This is a partial structural diagram of the present invention;

[0024] Figure 4 This is a schematic diagram of the heat exchange plate structure of the present invention;

[0025] Figure 5 This is a schematic diagram showing the disassembled structure of the heat exchange plate of the present invention;

[0026] Figure 6 This is a schematic diagram of the internal structure of the heat exchange plate of the present invention in half section.

[0027] Figure 7 This is a schematic diagram of the high thermal conductivity layer structure of the present invention;

[0028] Figure 8 This is a schematic diagram of the corrosion-resistant layer structure of the present invention;

[0029] Figure 9 This is a schematic diagram of the high-strength impact layer structure of the present invention;

[0030] Figure 10 This is a schematic diagram of the internal structure of the disturbance sleeve in half section according to the present invention;

[0031] Figure 11This is a schematic diagram of the disturbance sleeve deformation structure of the present invention;

[0032] Figure 12 This is a schematic diagram of the internal structure of the disturbance sleeve after deformation.

[0033] Explanation of the labels in the diagram:

[0034] 1. Outer casing; 101. Support feet; 2. Natural gas inlet pipe; 201. Natural gas manifold inlet pipe; 202. Branch pipe one; 3. Natural gas outlet pipe; 301. Natural gas manifold outlet pipe; 302. Branch pipe two; 4. Refrigerant inlet pipe; 401. Refrigerant manifold inlet pipe; 402. Branch pipe three; 5. Refrigerant outlet pipe; 501. Refrigerant manifold outlet pipe; 502. Branch pipe four; 6. Heat exchange plate; 601. Thin metal plate one; 60 2. Thin metal plate II; 603. Microchannel; 604. Gas phase channel; 605. Gas-liquid two-phase channel; 606. Liquid phase channel; 607. High thermal conductivity layer; 6071. Longitudinal protrusion; 608. Corrosion resistant layer; 609. High-strength impact resistant layer; 610. Cooling plate; 7. Disturbance sleeve; 701. Shape memory alloy sleeve; 702. Elastic sleeve; 703. Hole; 704. Elastic film; 705. Expansion medium. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example 1:

[0037] Please see Figures 1-4 A microchannel heat exchanger for natural gas liquefaction includes a shell 1, a heat exchange plate 6, and a disturbance sleeve 7. A natural gas inlet pipe 2 and a natural gas outlet pipe 3 are symmetrically embedded and fixed in the inner cavity of one side of the shell 1. One end of the natural gas inlet pipe 2 and the natural gas outlet pipe 3 are respectively connected to a natural gas collecting inlet pipe 201 and a natural gas collecting outlet pipe 301. A condensate inlet pipe 4 and a condensate outlet pipe 5 are symmetrically embedded and fixed in the inner cavity of the other side of the shell 1. One end of the condensate inlet pipe 4 and the condensate outlet pipe 5 are respectively connected to a condensate collecting inlet pipe 401 and a condensate collecting outlet pipe 501.

[0038] Specifically, multiple L-shaped support feet 101 are uniformly fixedly connected to the lower surface of the outer shell 1. The outer shell 1 is a rectangular sleeve with a hollow interior. Multiple branch pipes 402 and 502 are uniformly connected to the outer surfaces of the refrigerant inlet pipe 401 and the refrigerant outlet pipe 501, respectively. The upper end of the branch pipe 402 is fixedly connected to and communicates with the refrigeration plate 610, and the lower end of the branch pipe 502 is fixedly connected to and communicates with the refrigeration plate 610. The natural gas inlet pipe 201 is located in the upper part of the inner cavity of the outer shell 1, the natural gas outlet pipe 301 is located in the lower part of the inner cavity of the outer shell 1, the refrigerant inlet pipe 401 is located in the lower part of the inner cavity of the outer shell 1, and the refrigerant outlet pipe 501 is located in the upper part of the inner cavity of the outer shell 1.

[0039] Furthermore, the operator first starts the equipment via the control panel on the outside of the outer casing 1, putting it into standby mode. The operator then opens the refrigerant inlet pipe 4, which is made of 316L stainless steel and features a low-temperature resistant shut-off valve to prevent refrigerant leakage at low temperatures. The refrigerant enters through the refrigerant inlet pipe 4. The inner wall of the refrigerant manifold inlet pipe 401 is polished to ensure uniform refrigerant distribution. The refrigerant is then distributed from the refrigerant manifold inlet pipe 401 to each branch pipe 402. The diameter of the branch pipe 402 is smaller than that of the refrigerant manifold inlet pipe 401, and its end is connected to the refrigeration plate 610 by silver-copper alloy brazing to ensure lossless transfer of cooling capacity. 02 The condensate is delivered to the cooling plate 610 of the heat exchange plate 6 (the cooling plate 610 is made of copper-nickel alloy, and its internal flow channel is connected to the third branch pipe 402 and the fourth branch pipe 502, which can uniformly transfer the cooling capacity). The condensate flows in the cooling plate 610 and releases the cooling capacity. Then it flows into the condensate collection outlet pipe 501 through the fourth branch pipe 502. The condensate collection outlet pipe 501 is connected to the condensate outlet pipe 5 through a flange. The flange face is equipped with a low-temperature resistant asbestos gasket to ensure a seal. Finally, it is discharged from the condensate outlet pipe 5 to the external recovery equipment. The flow path of the condensate is designed to be counter-current to ensure that the temperature difference between it and the natural gas is maximized, thereby improving the heat transfer efficiency.

[0040] Open the valve of natural gas inlet pipe 2, and let the liquefied natural gas enter the natural gas manifold inlet pipe 201 through the natural gas inlet pipe 2. The natural gas manifold inlet pipe 201 and the branch pipe 202 are fixed by welding to prevent the natural gas from falling off under high pressure. The natural gas is distributed to each branch pipe 202 by the natural gas manifold inlet pipe 201. The natural gas and the condensate flow in opposite directions to form countercurrent heat exchange. In the entire heat exchange process, the coldest end of the hot fluid (natural gas) and the coldest end of the cold fluid (condensate) are on the same side, while the hottest end is on the other side. Under the same heat exchange area, the heat transfer rate is the highest, the temperature difference distribution of countercurrent heat exchange is more uniform, and the wall temperature gradient is gentle. This design not only improves the heat exchange efficiency, but also reduces the risk of local overcooling or overheating, ensuring the stable operation of the system.

[0041] Example 2:

[0042] Please see Figures 1-9A microchannel heat exchanger for natural gas liquefaction includes a heat exchange plate 6 and multiple microchannels 603 formed in the inner cavity of the heat exchange plate 6. A gas phase channel 604 is formed in the upper part of the inner cavity of the heat exchange plate 6, a gas-liquid two-phase channel 605 is formed in the middle part of the inner cavity of the heat exchange plate 6, and a liquid phase channel 606 is formed in the lower part of the inner cavity of the heat exchange plate 6. A high thermal conductivity layer 607 is fixed in the inner cavity of the gas phase channel 604, a corrosion-resistant layer 608 is fixed in the inner cavity of the gas-liquid two-phase channel 605, and a high-strength impact-resistant layer 609 is fixedly connected in the inner cavity of the liquid phase channel 606. There are multiple heat exchange plates 6, and a cooling plate 610 is fixed between adjacent pairs.

[0043] Specifically, multiple branch pipes 202 and 302 are uniformly connected to the outer surfaces of the natural gas inlet pipe 201 and the natural gas outlet pipe 301, respectively. The lower end of branch pipe 202 is fixedly connected to the upper surface of the heat exchange plate 6 and is connected to the gas phase channel 604 through a micro-channel 603. The upper end of branch pipe 302 is fixedly connected to the lower surface of the heat exchange plate 6 and is connected to the liquid phase channel 606 through a micro-channel 603. The gas phase channel 604 and the gas-liquid two-phase channel 605 are connected through a micro-channel 603. The gas-liquid two-phase channel 605 and the liquid phase channel 606 are connected through a micro-channel 603. 4 is a hollow rectangular sleeve. The inner wall of the gas phase channel 604 is uniformly fixed with multiple longitudinal protrusions 6071. The corrosion-resistant layer 608 is a narrow slit shape with semi-circular upper and lower ends. The high-strength impact-resistant layer 609 is elliptical. There are multiple heat exchange plates 6 and cooling plates 610. The outer surfaces of heat exchange plates 6 and cooling plates 610 have the same shape and size. Heat exchange plates 6 and cooling plates 610 are arranged alternately and welded together. Heat exchange plate 6 is composed of thin metal plate one 601 and thin metal plate two 602 spliced ​​together. Thin metal plate one 601 and thin metal plate two 602 are welded together to form a whole rectangular plate.

[0044] Furthermore, in the initial cooling stage of natural gas, natural gas is transported to the gas phase channel 604 of the heat exchange plate 6 through the first pipe 202. The gas phase channel 604 is rectangular, which increases the flow diameter, reduces the pressure drop, and the large surface area is conducive to heat transfer. The high thermal conductivity layer 607 (the high thermal conductivity layer 607 is a graphene composite coating, which can improve the efficiency of cold transfer) on the inner wall of the gas phase channel 604 quickly receives the cold energy transferred by the cooling plate 610. The cold energy is transferred to the natural gas in the gas phase channel 604 through the first thin metal plate 601 and the second thin metal plate 602 (the first thin metal plate 601 and the second thin metal plate 602 are made of pure copper plates, which have excellent thermal conductivity). The natural gas completes the initial cooling during the flow in the gas phase channel 604. The longitudinal protrusions 6071 on the inner wall can enhance the gas turbulence. The surface of the longitudinal protrusions 6071 is covered with a coating of the same material as the high thermal conductivity layer 607, which strengthens the turbulence without affecting the cold transfer, thereby increasing the initial cooling range of the natural gas.

[0045] After initial cooling during the gas-liquid phase change stage, the natural gas enters the intermediate gas-liquid two-phase channel 605 through the microchannel 603. The gas-liquid two-phase channel 605 has a narrow slit-shaped cross-section (semi-circular at both ends), which increases the contact area between the gas-liquid mixture and the channel wall. The corrosion-resistant layer 608 (a polytetrafluoroethylene coating that can resist corrosion from trace amounts of acidic gases in natural gas) on the inner wall of the gas-liquid two-phase channel 605 isolates the gas-liquid mixture from corroding the channel substrate. The cooling plate 610 continuously transfers cooling energy. The natural gas continuously absorbs heat in the gas-liquid two-phase channel 605, gradually undergoing a gas-liquid phase change to form a gas-liquid two-phase mixture. The narrow slit structure of the gas-liquid two-phase channel 605 and the hydrophobicity of the gas surface inhibit the formation of a liquid film. The inner wall of the gas-liquid two-phase channel 605 is also covered with a superhydrophobic coating, which can further reduce liquid film adhesion and reduce the thickness of the liquid film.

[0046] When the liquid film in the gas-liquid two-phase channel 605 becomes too thick, the wall temperature rises. The shape memory alloy sleeve 701 (the shape memory alloy sleeve 701 is a nickel-titanium alloy, which is a typical shape memory alloy. Its thermoelastic martensitic phase transformation characteristics can achieve reversible deformation at low temperatures) senses the temperature change and undergoes a phase transformation, producing deformation. It changes from a circular tube of the same diameter to a circular tube with an inward arc convexity, changing the flow velocity of the gas-liquid mixture in the channel, increasing the flow velocity, impacting the tube wall, and disturbing the fluid.

[0047] Natural gas that has completed the gas-liquid phase change (mainly in liquid state) enters the subsequent liquid phase channel 606 through the micro-channel 603. The liquid phase channel 606 is an elliptical channel, which reduces the flow resistance of the liquid natural gas (compared to the resistance of a circular channel), facilitates smooth liquid flow, and prevents flow dead zones. The tapered outlet has a gradually narrowing design, which can guide the liquid natural gas to flow in a concentrated manner to the second branch pipe 302, avoiding local stagnation. The high-strength impact-resistant layer 609 on the inner wall of the liquid phase channel 606 (the high-strength impact-resistant layer 609 is a silicon carbide ceramic coating that can withstand the pressure impact during the flow of liquid natural gas) resists the flow impact of liquid natural gas on the liquid phase channel 606.

[0048] Example 3:

[0049] Please see Figure 1 , Figure 2 , Figure 3 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12A microchannel heat exchanger for natural gas liquefaction includes a disturbance sleeve 7, and multiple shape memory alloy sleeves 701 uniformly and fixedly connected to the inner cavities of a gas-liquid two-phase channel 605 and a liquid phase channel 606. An elastic sleeve 702 is fixedly connected to the inner wall of the shape memory alloy sleeve 701. An expansion medium 705 is filled between the shape memory alloy sleeve 701 and the elastic sleeve 702. Multiple holes 703 are opened on the outer surface of the elastic sleeve 702, and an elastic film 704 is fixed in the inner cavity of the holes 703.

[0050] Specifically, multiple shape memory alloy sleeves 701 are evenly distributed on the inner walls of the gas-liquid two-phase channel 605 and the liquid phase channel 606. The shape of the shape memory alloy sleeves 701 located on the inner wall of the gas-liquid two-phase channel 605 is the same as that of the gas-liquid two-phase channel 605, and the shape of the shape memory alloy sleeves 701 located on the inner wall of the liquid phase channel 606 is the same as that of the liquid phase channel 606.

[0051] Furthermore, when the temperature within the gas-liquid two-phase channel 605 remains abnormal, it indicates that the first-stage disturbance is ineffective. The heat from the gas-liquid two-phase channel 605 is transferred to the elastic sleeve 702 of the disturbance sleeve 7 (the elastic sleeve 702 is made of fluororubber, which has excellent chemical corrosion resistance and low-temperature resistance; for example, DuPont Chemours' Viton GFLT-200S fluororubber can maintain elasticity at low temperatures). This causes the expansion medium 705 within the elastic sleeve 702 (the expansion medium 705 is a low-boiling-point working fluid such as ethane or propane, with boiling points of -88.6℃ and -42.1℃ respectively, which can expand in volume by 600 times after vaporization). (Above) The heat absorption and vaporization expansion cause the elastic film 704 to deform under pressure, which in turn causes the elastic film 704 (elastic film 704 is a modified rubber and plastic material, such as Duken FC ultra-low temperature FUNIS, which uses ACMF precision micro-foaming technology, with nitrile rubber as the base material, and is modified by low-temperature active formula. It has been used in LNG storage tank pipeline sealing and liquid ammonia transportation system. Dynamic bending test shows that it can withstand more than 100,000 bends at -200℃ without cracking) to bulge out, forming an arc-shaped protrusion. This creates a secondary disturbance to the gas-liquid two-phase mixture, breaks the liquid film, and generates stronger physical vibration through fluid impact, further breaking down the barrier.

[0052] When the temperature of the liquefied natural gas in the liquid phase channel 606 stratifies (dead zones, freezing, or waxing occur), the shape memory alloy sleeve 701 on the outside of the liquid phase channel 606 senses the temperature change and undergoes a phase change bulge, transforming from a circular tube of the same diameter into an inwardly arc-shaped circular tube. This changes the flow rate of the liquefied natural gas and creates an initial disturbance. If the temperature stratification continues, the expansion medium 705 absorbs heat and expands, causing the elastic film 704 to deform and bulge, forming an arc-shaped protrusion. This creates a secondary disturbance to the liquefied natural gas, breaking the dead zone and preventing freezing. After the liquefied natural gas flows stably in the liquid phase channel 606, it flows through the second branch pipe 302 into the natural gas collection outlet pipe 301, and finally exits from the natural gas outlet pipe 3 to the external storage device. The check valve in the natural gas outlet pipe 3 prevents the liquefied natural gas from flowing back.

[0053] Working principle: During operation, the operator opens the valve of the condensate inlet pipe 4, allowing the condensate to enter the condensate manifold inlet pipe 401. From the manifold inlet pipe 401, the condensate is distributed to the branch pipes 402. The branch pipes 402 then transport the condensate to the cooling plates 610 of the heat exchange plate 6. The condensate flows within the cooling plates 610, releasing cooling energy, and then flows through the branch pipes 502 into the condensate manifold outlet pipe 501. Finally, it is discharged from the condensate outlet pipe 5 to the external recovery equipment. Simultaneously, the valve of the natural gas inlet pipe 2 is opened, allowing liquefied natural gas to enter the natural gas manifold inlet pipe 201. From the natural gas manifold inlet pipe 201, the liquefied natural gas is distributed to the branch pipes 202. The natural gas then reacts with the cooling... The condenser flows in the opposite direction, forming countercurrent heat exchange. In the initial cooling stage, natural gas is transported to the gas phase channel 604 of the heat exchange plate 6 through the branch pipe 202. The high thermal conductivity layer 607 on the inner wall of the gas phase channel 604 quickly receives the cooling energy transferred by the cooling plate 610. The natural gas undergoes initial cooling during its flow within the gas phase channel 604. After initial cooling, the natural gas enters the middle gas-liquid two-phase channel 605 along the micro-channel 603, gradually undergoing gas-liquid phase change to form a gas-liquid two-phase mixture. The narrow slit structure of the gas-liquid two-phase channel 605 and the hydrophobic surface of the gas inhibit the formation of a liquid film. The inner wall of the gas-liquid two-phase channel 605 is also covered with a superhydrophobic coating, which can further reduce liquid film adhesion and reduce the liquid film thickness. When an excessively thick liquid film appears in the gas-liquid two-phase channel 605, the wall temperature rises. The shape memory alloy sleeve 701 senses the temperature change and undergoes a phase change, deforming from a circular tube of the same diameter to a circular tube with an inwardly arc-shaped bulge. This alters the flow velocity of the gas-liquid mixture within the channel, increasing the velocity, impacting the tube wall, and disturbing the fluid. If the temperature remains abnormal, the heat from the gas-liquid two-phase channel 605 is transferred to the interior of the elastic sleeve 702 of the disturbance sleeve 7, causing the expansion medium 705 within the elastic sleeve 702 to absorb heat, vaporize, and expand. The expansion pressure pushes the elastic film 704 to deform, causing it to bulge and form an arc-shaped bulge, creating a secondary disturbance to the gas-liquid two-phase mixture. The natural gas, having completed the gas-liquid phase change, then enters through the microchannel 603. When the liquid natural gas in the liquid phase channel 606 enters the downstream section, and temperature stratification occurs, the shape memory alloy sleeve 701 on the outside of the liquid phase channel 606 senses the temperature change and undergoes a phase change bulge, changing from a circular tube of the same diameter to a circular tube with an inward arc-shaped bulge. This changes the flow rate of the liquid natural gas and creates an initial disturbance. If the temperature stratification continues, the expansion medium 705 absorbs heat and expands, and the elastic film 704 deforms, pushing the elastic film 704 to bulge and form an arc-shaped bulge, creating a secondary disturbance to the liquid natural gas. After the liquid natural gas flows stably in the liquid phase channel 606, it flows into the natural gas collection outlet pipe 301 through the second branch pipe 302, and is finally discharged from the natural gas outlet pipe 3 to the external storage device.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and not restrictive.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A microchannel heat exchanger for natural gas liquefaction, characterized in that: include: The outer shell (1) has a natural gas inlet pipe (2) and a natural gas outlet pipe (3) symmetrically embedded and fixed in the inner cavity of one side. One end of the natural gas inlet pipe (2) and the natural gas outlet pipe (3) are respectively connected to a natural gas collection inlet pipe (201) and a natural gas collection outlet pipe (301). The inner cavity of the other side of the outer shell (1) has a condensate inlet pipe (4) and a condensate outlet pipe (5) symmetrically embedded and fixed. One end of the condensate inlet pipe (4) and the condensate outlet pipe (5) are respectively connected to a condensate collection inlet pipe (401) and a condensate collection outlet pipe (501). The heat exchange plate (6) includes multiple micro-channels (603) formed in the inner cavity of the heat exchange plate (6). A gas phase channel (604) is formed in the upper part of the inner cavity of the heat exchange plate (6), a gas-liquid two-phase channel (605) is formed in the middle part of the inner cavity of the heat exchange plate (6), and a liquid phase channel (606) is formed in the lower part of the inner cavity of the heat exchange plate (6). A high thermal conductivity layer (607) is fixed in the inner cavity of the gas phase channel (604), a corrosion-resistant layer (608) is fixed in the inner cavity of the gas-liquid two-phase channel (605), and a high-strength impact-resistant layer (609) is fixedly connected in the inner cavity of the liquid phase channel (606). There are multiple heat exchange plates (6), and a cooling plate (610) is fixed between two adjacent plates. The disturbance sleeve (7) includes multiple shape memory alloy sleeves (701) uniformly and fixedly connected to the inner cavities of the gas-liquid two-phase channel (605) and the liquid phase channel (606). An elastic sleeve (702) is fixedly connected to the inner wall of the shape memory alloy sleeve (701). An expansion medium (705) is filled between the shape memory alloy sleeve (701) and the elastic sleeve (702). Multiple holes (703) are opened on the outer surface of the elastic sleeve (702). An elastic film (704) is fixed in the inner cavity of the hole (703).

2. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The lower surface of the outer shell (1) is uniformly fixed with multiple L-shaped support feet (101), and the outer shell (1) is a rectangular sleeve with a hollow interior.

3. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The outer surfaces of the natural gas inlet pipe (201) and the natural gas outlet pipe (301) are uniformly connected to a plurality of branch pipes one (202) and two branch pipes (302). The lower end of the branch pipe one (202) is fixedly connected to the upper surface of the heat exchange plate (6) and is connected to the gas phase channel (604) through a micro channel (603). The upper end of the branch pipe two (302) is fixedly connected to the lower surface of the heat exchange plate (6) and is connected to the liquid phase channel (606) through a micro channel (603).

4. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The outer surfaces of the refrigerant inlet pipe (401) and the refrigerant outlet pipe (501) are uniformly connected to a plurality of branch pipes three (402) and four (502). The upper end of the branch pipe three (402) is fixedly connected to and connected to the refrigeration plate (610), and the lower end of the branch pipe four (502) is fixedly connected to and connected to the refrigeration plate (610).

5. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The natural gas inlet pipe (201) is located in the upper part of the inner cavity of the outer shell (1), the natural gas outlet pipe (301) is located in the lower part of the inner cavity of the outer shell (1), the refrigerant inlet pipe (401) is located in the lower part of the inner cavity of the outer shell (1), and the refrigerant outlet pipe (501) is located in the upper part of the inner cavity of the outer shell (1).

6. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The gas phase channel (604) and the gas-liquid two-phase channel (605) are connected by a micro-channel (603), and the gas-liquid two-phase channel (605) and the liquid phase channel (606) are connected by a micro-channel (603).

7. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The gas phase channel (604) is a rectangular sleeve with a hollow interior. Multiple longitudinal protrusions (6071) are uniformly fixedly connected to the inner wall of the gas phase channel (604). The corrosion-resistant layer (608) is a narrow slit shape with semi-circular upper and lower ends. The high-strength impact-resistant layer (609) is elliptical.

8. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: There are multiple heat exchange plates (6) and cooling plates (610). The outer surfaces of the heat exchange plates (6) and cooling plates (610) have the same shape and size. The heat exchange plates (6) and cooling plates (610) are arranged alternately and welded together.

9. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The shape memory alloy sleeves (701) are numerous and evenly distributed on the inner walls of the gas-liquid two-phase channel (605) and the liquid phase channel (606). The shape memory alloy sleeves (701) located on the inner wall of the gas-liquid two-phase channel (605) are the same as those of the gas-liquid two-phase channel (605), and the shape memory alloy sleeves (701) located on the inner wall of the liquid phase channel (606) are the same as those of the liquid phase channel (606).

10. A microchannel heat exchanger for natural gas liquefaction according to claim 1, characterized in that: The heat exchange plate (6) is composed of a thin metal plate one (601) and a thin metal plate two (602) spliced ​​together. The thin metal plate one (601) and the thin metal plate two (602) are welded together to form a whole rectangular plate.

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