A material concentration system and method based on a vortex tube and a VMD system

Abstract

The application discloses a material concentration system and method based on a vortex tube and a VMD system, and the system comprises a vortex tube, a first heat exchanger, a second heat exchanger and a VMD system. High-pressure natural gas inflow enters the vortex tube to generate hot-end flow and cold-end flow, and provides heat source and cold source for the first heat exchanger and the second heat exchanger respectively. After being preheated by the first heat exchanger, the material to be concentrated enters a material liquid side of the VMD system, under the action of the transmembrane steam pressure difference formed by negative pressure, water vaporizes and penetrates the membrane to enter the cold side, is condensed into liquid water by the second heat exchanger and is discharged by a drainage pump, and the material liquid side obtains concentrated material. After heat exchange, the cold and hot end natural gas is supplied to a downstream pipe network after being converged and stabilized by an ejector, the application fully utilizes the natural gas station residual pressure for heating and refrigeration, provides operation driving force for the VMD system, simultaneously completes natural gas pressure regulation and material low-temperature concentration, and is suitable for industrial wastewater, food, medicine, chemical industry and other material concentration and natural gas station energy-saving reconstruction.

Description

Technical Field

[0001] This invention belongs to the technical field of natural gas transportation and energy-saving utilization and low-temperature concentration of industrial materials. Specifically, it relates to a material concentration system and method based on the coupling of natural gas gate station residual pressure recovery, vortex tube energy separation and vacuum membrane distillation. It is particularly suitable for integrated application scenarios of pressure energy recovery and low-energy concentration of industrial wastewater, food liquids and chemical solutions during high-pressure natural gas pressure regulation. Background Technology

[0002] In food processing, biopharmaceuticals, chemical production, and environmental water treatment, material concentration and dehydration are common and critical process steps. Currently, commonly used industrial concentration technologies include thermal evaporation, multi-effect evaporation, reverse osmosis, freeze drying, and membrane distillation. Traditional thermal evaporation and multi-effect evaporation are energy-intensive and operate at high temperatures, easily damaging heat-sensitive materials, and involve large equipment volumes and high investment and operating costs. Reverse osmosis is limited by osmotic pressure, making it difficult to achieve high concentration ratios, and has stringent requirements for water quality and material pretreatment. Vacuum membrane distillation (VMD) has become one of the mainstream technologies for low-temperature, high-efficiency concentration due to its advantages such as low operating temperature, high concentration ratio, good retention effect, and resistance to fouling. However, vacuum membrane distillation still has significant shortcomings in practical applications: on the one hand, it requires a stable low-temperature heat source to drive water vaporization, and most companies rely on steam or electric heating, resulting in high energy costs; on the other hand, it requires a continuous vacuum environment and a condensation cold source, leading to high power consumption in the vacuum pump and refrigeration system, resulting in low overall system energy efficiency and hindering its widespread adoption. Summary of the Invention

[0003] This invention aims to provide a material concentration system and method based on the utilization of residual pressure at natural gas gate stations, which couples vortex tubes with vacuum membrane distillation. This system deeply integrates the fields of natural gas transportation and industrial material concentration, realizing the integrated operation of residual pressure recovery and energy separation in natural gas transportation with low-temperature membrane distillation and vacuum condensation in industrial material concentration. This achieves the technical effects of no external heat source, low energy consumption, high efficiency, safety and stability.

[0004] This invention provides a material concentration system based on vortex tubes and VMD systems, comprising: The vortex tube generates a cold end flow and a hot end flow when natural gas flows into it. The hot end of the vortex tube is connected to the first heat exchanger, and the cold end is connected to the second heat exchanger. The VMD system is a vacuum membrane distillation unit, which is internally separated into a feed side and a permeate side by a membrane, with the permeate side being a negative pressure environment. The material to be concentrated flows into the first heat exchanger to exchange heat with the hot end flow and is preheated. Then it enters the liquid side of the VMD system. Under the action of the transmembrane vapor pressure difference, the water in the material to be concentrated is evaporated and separated, and concentrated material is obtained on the liquid side. On the permeate side, steam is generated. The steam enters the second heat exchanger to exchange heat with the cold end flow and is condensed to obtain liquid water. The hot end of the natural gas flows out from the first heat exchanger, and the cold end flows out from the second heat exchanger. The two flow together to form the pressure-regulated natural gas supply.

[0005] This invention deeply couples vortex tube energy separation technology with vacuum membrane distillation (VMD) technology, directly utilizing the pressure energy of the natural gas flow itself to achieve simultaneous production of hot and cold air. While completing natural gas pressure regulation, it also achieves efficient recovery and resource utilization of residual pressure energy, fundamentally solving the problems of complete waste of pressure energy and low energy efficiency in traditional pressure regulation methods.

[0006] Using the hot-end airflow of the vortex tube as the heat source of the first heat exchanger, the material to be concentrated is preheated, providing a stable and continuous low-temperature driving heat source for the VMD system. No external electric heating, steam, or boiler equipment is required, significantly reducing the heating energy consumption and operating costs of the material concentration process. Using the cold-end airflow of the vortex tube as the cold source of the second heat exchanger, the water vapor on the permeate side of the VMD system is directly condensed. No chiller unit, cooling water system, or external refrigeration equipment is needed, achieving zero-refrigeration energy consumption operation, simplifying the system structure, and reducing equipment investment. The VMD system relies on the transmembrane vapor pressure difference to drive water evaporation and separation, completing material concentration under medium and low temperature conditions without damaging heat-sensitive material components. The concentration process is gentle, with high separation efficiency and good membrane retention, making it widely applicable to various material concentration scenarios such as industrial wastewater, food, pharmaceuticals, and chemicals. Natural gas is re-combined and output after pressure regulation and heat exchange via the vortex tube, without affecting the normal downstream gas supply. This allows for the parallel utilization of residual pressure and gas supply. The system has strong compatibility and stable operation, and can be directly used with natural gas gate stations and pressure regulating stations. The system has no complex moving parts, a compact structure, reliable operation, and low maintenance costs. It can work continuously and stably for a long time, and solves two major industry pain points: high energy consumption for natural gas pressure regulation and high cost of industrial material concentration.

[0007] Moisture in the material is separated in the form of steam and condensed into pure liquid water, which can be recycled and reused without secondary pollution or chemical additives. It meets the development requirements of green, low-carbon, energy-saving and consumption-reducing and circular economy, and has significant economic and environmental benefits.

[0008] The first heat exchanger and / or the second heat exchanger can be shell-and-tube heat exchangers.

[0009] This invention uses a shell-and-tube heat exchanger as the first and / or second heat exchanger. The shell side and tube side can be flexibly arranged to accommodate the passages for natural gas, materials, and steam. The heat exchange structure is mature and reliable, with a large heat exchange area and high heat transfer efficiency. It can stably achieve efficient heat transfer between the hot and cold airflows and materials and steam in the vortex tube, ensuring continuous and stable operation of the system.

[0010] The tube-side and shell-side passages of a shell-and-tube heat exchanger are flexibly interchangeable. Natural gas can be arranged in the tube side and the material or steam in the shell side, or vice versa. This greatly improves the system's adaptability and installation flexibility, and can be adapted to different site spaces, pressure levels and fluid characteristics.

[0011] Preferably, it also includes a vacuum pump, which is sequentially connected to the second heat exchanger cavity and the cold side of the VMD system to establish a negative pressure environment on the cold side; a pressure sensor, which is used to monitor the negative pressure environment on the cold side; and a valve, which is located between the vacuum pump and the second heat exchanger.

[0012] This invention connects a vacuum pump sequentially to the second heat exchanger chamber and the cold side of the VMD system. This allows for the simultaneous establishment of a negative pressure environment for both the VMD permeate side and the condensation chamber within the same vacuum loop. A pressure sensor monitors the vacuum level of the VMD cold side and the second heat exchanger chamber in real time, enabling precise online sensing of the negative pressure state. This provides data support for automated system control, ensuring stable transmembrane vapor pressure differential and improving material concentration efficiency and operational consistency. A valve is installed between the vacuum pump and the second heat exchanger. Combined with the pressure sensor, this allows for intelligent on / off switching and pressure maintenance of the vacuum loop: when the vacuum level reaches a set value, the valve closes and the vacuum pump stops, automatically maintaining a dynamic negative pressure balance within the sealed chamber; when the negative pressure is insufficient, the valve opens and the vacuum pump restarts to replenish the pressure.

[0013] It also includes a drain pump, which is connected to the second heat exchanger, to discharge the liquid water formed by condensation. It can discharge the liquid water formed by steam condensation in a timely and stable manner, avoiding the accumulation of condensate inside the heat exchanger cavity, ensuring a stable vacuum environment, maintaining high-efficiency heat exchange and condensation efficiency, and improving the continuous operation capability of the system.

[0014] It also includes an ejector. The hot end of the natural gas flows out from the first heat exchanger, and the cold end flows out from the second heat exchanger. After the two flows converge at the ejector, they enter the downstream natural gas pipeline network. By setting up an ejector, this invention combines and stabilizes the natural gas from the hot end of the vortex tube after heat exchange in the first heat exchanger and the natural gas from the cold end after heat exchange in the second heat exchanger, achieving uniform mixing of hot and cold gas flows, ensuring stable output natural gas temperature and pressure, and not affecting the normal gas supply to the downstream natural gas pipeline network.

[0015] The present invention also provides a material concentration method based on vortex tubes and VMD systems, comprising: The incoming natural gas flows into the vortex tube, generating a cold end flow and a hot end flow. The hot end flow enters the first heat exchanger, and the cold end flow enters the second heat exchanger. The material to be concentrated flows into the first heat exchanger to exchange heat with the hot end flow and be preheated, and then enters the liquid side of the VMD system. The permeate side of the VMD system is a negative pressure environment. The water in the material to be concentrated on the feed side evaporates under the action of the transmembrane vapor pressure difference and enters the permeate side through the membrane to generate vapor. The steam enters the second heat exchanger and exchanges heat with the cold end flow of the vortex tube, and after condensation, it becomes liquid water. After heat exchange, the cold and hot end streams merge to form regulated natural gas, which is then supplied to the downstream pipeline network. This method simultaneously utilizes residual natural gas pressure and concentrates the material, achieving energy recovery and low-temperature membrane distillation during natural gas pressure regulation. This cross-domain process coupling significantly improves overall energy utilization. The hot end stream generated by the vortex tube preheats the material, eliminating the need for external steam or electric heating sources, achieving zero-heating-energy-consumption membrane distillation and significantly reducing concentration operating costs. The cold end stream generated by the vortex tube condenses water vapor, eliminating the need for refrigeration units and cooling water systems, achieving zero-refrigeration-energy-consumption vapor liquefaction, simplifying the system and reducing energy consumption. A negative pressure environment creates a transmembrane vapor pressure difference, enabling efficient evaporation and separation of water at medium and low temperatures and low pressure differences, without damaging heat-sensitive materials. This results in high concentration efficiency and a wide range of applicable materials. The membrane module achieves efficient gas-liquid separation, complete material retention, high concentrate purity, and recyclable condensate, eliminating secondary pollution and making it environmentally friendly. After heat exchange between the hot and cold ends, the natural gas is combined and supplied downstream at a stable pressure, without affecting the stability or quality of the gas supply. The gate station can operate normally, and the system has strong compatibility. The overall process is simple, with no complex moving parts, stable operation, low maintenance costs, and can be continuously automated, making it suitable for large-scale industrial applications. Attached Figure Description

[0016] Figure 1 This is a flowchart provided in an embodiment of this application.

[0017] Among them, vortex tube 1, natural gas inlet 2, first heat exchanger 3, second heat exchanger 4, valve 5, vacuum pump 6, drain pump 7, VMD system 8, membrane 9, ejector 10, material to be concentrated inlet 11. Detailed Implementation

[0018] It should be noted that the terms "comprising" and "having" are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or modules that are not explicitly listed or that are inherent to these processes, methods, products, or devices.

[0019] Examples, as described below with reference to the appendix Figure 1 The specific embodiments of the present invention will be further described in detail below. This embodiment takes the pipeline natural gas PNG gate station as the application scenario, and couples the natural gas residual pressure recovery with the separation of cold and hot energy and the vacuum membrane distillation (VMD) material concentration system to achieve the dual goals of cascade utilization of natural gas gate station energy and low-energy concentration of industrial materials.

[0020] The coupling system of vortex tube and vacuum membrane distillation based on the utilization of residual pressure at natural gas gate stations in this invention mainly includes a vortex tube 1, natural gas inlet 2, first heat exchanger 3, second heat exchanger 4, valve 5, vacuum pump 6, drain pump 7, VMD system 8, membrane 9, ejector 10, material to be concentrated inlet 11, natural gas pressure regulating pipeline, material conveying pipeline, condensate discharge pipeline, and supporting control system (PLC), pressure sensor, temperature sensor, flow sensor and other auxiliary equipment.

[0021] The vortex tube 1 is used to receive the high-pressure natural gas flow 2, and uses the pressure energy of the natural gas to achieve energy separation, outputting a high-temperature hot gas flow and a low-temperature cold gas flow to provide a power source for subsequent heat exchange and VMD process; wherein, the natural gas flow 2 refers to high-pressure pipeline natural gas from long-distance pipeline, with a pressure range of 1.6MPa~4.0MPa and a temperature of 15℃~30℃; The first heat exchanger 3 is a heat exchange carrier. It can be a shell and tube heat exchanger to realize the heat transfer between the high-temperature airflow at the hot end of the vortex tube 1 and the incoming flow 11 of the material to be concentrated, and to preheat the material. The second heat exchanger 4 is a cold exchange medium. It can be a shell-and-tube heat exchanger to realize the condensation of water vapor generated by the VMD system 8 by the low-temperature airflow at the cold end of the vortex tube 1, and further realize the recovery of condensate and utilization of cold energy. Vacuum pump 6 is connected in sequence to the second heat exchanger 4 and the permeate side of VMD system 8 through valve 5, in order to establish a high vacuum environment on the cold side of VMD system 8 and form a transmembrane vapor pressure difference. The drain pump 7 is connected to the condensate outlet of the second heat exchanger 4 to discharge the condensed fresh water from the system, thereby realizing water resource recovery. VMD system 8 is a vacuum membrane distillation component. Inside, a membrane 9 separates the feed side from the permeate side, and the material is dehydrated and concentrated by utilizing the transmembrane vapor pressure difference. In the prior art, the membrane 9 can be a hydrophobic microporous membrane made of polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) with a pore size of 0.1 μm to 0.5 μm. It has water-repellent and vapor-permeable properties, allowing only water vapor to pass through while retaining non-volatile solutes in the material. The ejector 10 is connected to the hot end and cold end outlet of the vortex tube 1 and the downstream pipeline of the natural gas gate station to achieve the mixing and stabilization of hot and cold gas flow and ensure the stability of downstream natural gas supply pressure. The material to be concentrated in stream 11 is an industrial material that needs to be dehydrated and concentrated, including but not limited to high-salt wastewater, food concentrate, pharmaceutical intermediate solution, chemical raw material solution, etc., which is the object of VMD system 8.

[0022] In this embodiment, as Figure 1 As shown, natural gas flow 2 originates from the city's high-pressure gas transmission trunk pipeline, with specific parameters of pressure 3.2 MPa, temperature 25°C, and methane content ≥95%, conforming to the gas source standards of the "Urban Gas Design Code" GB50028-2006. Natural gas at this pressure level contains a significant amount of pressure energy. Directly reducing the pressure through a pressure reducing valve would result in approximately 80% wasted pressure energy, along with throttling and temperature drops, increasing subsequent processing energy consumption. The PNG system not only undertakes the functions of natural gas transmission, pressure regulation, and supply but also serves as the driving gas source for the vortex tube 1, converting the pressure energy of natural gas into heat and cold energy, achieving cascaded energy utilization. Compared to traditional natural gas gate stations that only have pressure regulation, metering, and filtration functions, the PNG system in this embodiment, through coupling with the vortex tube 1, expands the dimensions of energy utilization, realizing the dual functions of gas source supply and energy recovery. Natural gas flow 2 is directly connected to the tangential inlet of the vortex tube 1 through a high-pressure pipeline, eliminating the need for additional pressure transformers or energy conversion equipment, and utilizing the pressure energy of the natural gas itself to drive the operation of the vortex tube 1.

[0023] The vortex tube 1 is a heat exchange device without moving parts based on the energy separation effect of fluid dynamics. It is existing technology and has been widely used in other prior patents filed by the applicant. Its core principle is the stratified heat exchange and energy redistribution of high-speed rotating airflow. High-pressure natural gas flow 2 enters the vortex chamber of the vortex tube 1 tangentially. Under the action of centrifugal force, the high-speed rotating airflow is divided into inner and outer layers. The outer layer is close to the inner wall of the vortex tube 1, with a large rotation radius and strong centrifugal force. The collision and friction between airflow molecules are intensified, and kinetic energy is converted into internal energy. At the same time, the throttling effect of the hot end valve further compresses the airflow, causing the temperature of the outer airflow to rise, and finally forming a high-temperature hot airflow with a temperature range of 65℃~90℃ and a pressure of 0.25MPa~0.35MPa. This hot airflow serves as the heat energy source of the system and is connected to the first heat exchanger 3. The inner airflow is close to the central axis of the vortex tube 1, with a small radius of rotation and weak centrifugal force. During the expansion process, the airflow consumes internal energy and at the same time undergoes countercurrent heat exchange with the outer high-temperature airflow. That is, the outer layer transfers heat to the hot end, and the inner layer transfers heat to the cold end, which significantly reduces the temperature of the inner airflow and finally forms a low-temperature cold airflow with a temperature range of -10℃ to -30℃ and a pressure of 0.25MPa to 0.35MPa. This cold airflow serves as the cold energy source of the system and is connected to the second heat exchanger 4.

[0024] The energy separation efficiency of the vortex tube 1 is closely related to the inlet pressure, the opening degree of the hot-end valve 5, and the structure of the vortex chamber. In this embodiment, by adjusting the opening degree of the hot-end valve, the discharge volume of the hot airflow is controlled, thereby adjusting the temperature and flow rate of the cold airflow. When the opening degree of the hot-end valve increases, the discharge volume of the hot airflow increases, the airflow returning to the cold end decreases, and the temperature of the cold airflow decreases but the flow rate decreases. When the opening degree of the hot-end valve decreases, the discharge volume of the hot airflow decreases, the airflow returning to the cold end increases, and the temperature of the cold airflow increases but the flow rate increases. By precisely adjusting the opening degree of the hot-end valve, the parameters of the hot and cold airflows can be matched as needed, ensuring compatibility with the VMD system 8 and the heat exchanger.

[0025] Natural gas flow 2 is directly connected to the tangential inlet of vortex tube 1 without the need for intermediate energy conversion equipment. Therefore, the vortex tube 1 is driven directly by the pressure energy of natural gas without consuming electricity or fossil energy, thus realizing zero-cost recovery of residual pressure at the natural gas gate station.

[0026] The hot end of the vortex tube 1 is connected to the first heat exchanger 3. The hot end outlet of the vortex tube 1 is connected to the tube-side inlet of the first heat exchanger 3 via a pipeline, and the tube-side outlet of the first heat exchanger 3 is connected to the hot end inlet of the ejector 10. The high-temperature hot gas flow generated by the vortex tube 1 is directly introduced into the first heat exchanger 3, providing a stable heat source for the preheating of the material to be concentrated in the inflow 11. There is no need to set up additional heating equipment such as electric heaters and steam heaters, which reduces equipment investment costs and operating energy consumption. At the same time, after the hot gas flow passes through the first heat exchanger 3, the temperature drops to 40℃~50℃ before entering the ejector 10, avoiding the safety hazards caused by the high-temperature gas flow directly entering the downstream pipeline network and improving system safety.

[0027] The cold end is connected to the second heat exchanger 4. The cold end outlet of the vortex tube 1 is connected to the tube-side inlet of the second heat exchanger 4 through a pipeline. The tube-side outlet of the second heat exchanger 4 is connected to the cold end inlet of the ejector 10. The low-temperature cold airflow generated by the vortex tube 1 is directly introduced into the second heat exchanger 4, providing a cold source for the condensation of water vapor generated by the VMD system 8. There is no need to set up additional refrigeration units, chillers or other refrigeration equipment, which greatly reduces the system's refrigeration energy consumption. At the same time, after the cold airflow passes through the second heat exchanger 4, the temperature rises to 10℃~20℃ before being connected to the ejector 10. This avoids the problem of natural gas condensation and condensation caused by the low-temperature airflow directly entering the downstream pipeline network, ensuring the quality of downstream natural gas supply.

[0028] The hot and cold ends of the vortex tube 1 are connected to the two inlets of the ejector 10, and the outlet of the ejector 10 is connected to the downstream pipeline network of the natural gas gate station. The ejector 10 mixes the hot and cold gas streams separated by the vortex tube 1, achieving precise pressure stabilization of the downstream natural gas supply pressure and avoiding pressure fluctuations caused by the separate discharge of hot and cold gas streams. At the same time, the ejector 10 uses the energy difference between the hot and cold gas streams to achieve mixing without power consumption, further improving the energy utilization efficiency of the system. In addition, the temperature of the mixed gas stream is stable at 20℃~30℃ and the pressure is stable at 0.2MPa~0.4MPa, which meets the gas demand of downstream users and ensures the stability and safety of natural gas supply.

[0029] Vacuum membrane distillation (VMD) is a membrane distillation technology based on phase change separation. It is an existing technology, and its core principle is a water vapor mass transfer process driven by transmembrane vapor pressure difference. The specific process is as follows: First, vaporization occurs on the feed side. The preheated material to be concentrated, stream 11, enters the feed side of the VMD system 8 and vaporizes on the surface of membrane 9, generating water vapor. Since membrane 9 is a hydrophobic microporous membrane, liquid material cannot pass through the membrane pores; only water vapor can diffuse through the pores to the permeate side.

[0030] Furthermore, through the establishment of the transmembrane vacuum, the vacuum pump 6 evacuates the transmembrane side of the VMD system 8, making the transmembrane pressure much lower than the saturated vapor pressure of the feed liquid side, forming a transmembrane vapor pressure difference, which serves as the core driving force for water vapor mass transfer.

[0031] Furthermore, water vapor condensation and recovery: water vapor passing through membrane 9 enters the second heat exchanger 4 and exchanges heat with the low-temperature airflow at the cold end of vortex tube 1. The water vapor condenses into liquid water and is discharged from the system through drainage pump 7, realizing the recycling of water resources. At the same time, material concentration is achieved. Water vapor on the liquid side continuously passes through membrane 9, and the solute concentration in the material continuously increases, ultimately achieving dehydration and concentration of the material. The concentrated material is discharged from VMD system 8 and enters subsequent storage or processing stages.

[0032] The VMD system 8 operates at a low temperature, requiring only a low-temperature heat source of 40℃~70℃, making it suitable for industrial waste heat and pressure utilization scenarios. Its high membrane rejection rate ensures complete retention of solutes in the material, guaranteeing the purity of the concentrated product. Furthermore, the VMD system 8 operates at low pressure, with a vacuum environment on the permeate side and atmospheric or medium pressure on the feed side, reducing the pressure resistance requirements of the equipment and lowering investment costs. It only requires the energy consumption of the vacuum pump 6 and the material transfer pump, significantly reducing energy consumption compared to traditional distillation processes.

[0033] The material to be concentrated, flowing 11, is connected to the shell-side inlet of the first heat exchanger 3 via a material transfer pump. The shell-side outlet of the first heat exchanger 3 is connected to the liquid-side inlet of the VMD system 8. The first heat exchanger 3 preheats the material to be concentrated, transferring the heat energy from the hot end of the vortex tube 1 to the material, raising the material temperature from the initial temperature of 15℃~30℃ to 40℃~60℃. This significantly reduces the vaporization energy consumption of the VMD system 8 and improves the material concentration efficiency. At the same time, the first heat exchanger 3 achieves cascaded utilization of heat energy, avoiding direct waste of high-temperature heat energy and improving the overall energy utilization rate of the system.

[0034] In this embodiment, membrane 9 can be a hollow fiber membrane or a flat sheet membrane, encapsulated within the components of VMD system 8, separating the feed liquid side from the permeate side. The permeate side of membrane 9 is connected to vacuum pump 6 and second heat exchanger 4. The hydrophobic microporous structure of membrane 9 ensures selective permeation of water vapor while preventing the permeation of liquid materials, achieving efficient separation of materials and water. The integrated encapsulation of membrane 9 and VMD system 8 simplifies the system structure, reduces piping connections, and lowers the risk of leakage. The connection between the permeate side and vacuum pump 6 and second heat exchanger 4 ensures the stable formation of transmembrane vapor pressure difference and rapid condensation of water vapor, improving the operational stability of VMD system 8.

[0035] The inlet of vacuum pump 6 is connected to the permeate side of VMD system 8 via the shell side of second heat exchanger 4. Vacuum pump 6 establishes a high vacuum environment on the permeate side of VMD system 8, forming a transmembrane vapor pressure difference to ensure efficient mass transfer of water vapor. Under the action of vacuum pump 6, water vapor on the permeate side is directly introduced into the shell side of second heat exchanger 4, realizing direct heat exchange between water vapor and cold airflow in the tube side, thus improving condensation efficiency. At the same time, vacuum pump 6 is equipped with a pressure sensor and valve 5, which can automatically adjust the pumping rate according to the permeate side pressure to avoid membrane 9 damage caused by excessively high vacuum or mass transfer efficiency reduction caused by excessively low vacuum.

[0036] The shell-side outlet of the second heat exchanger 4 is connected to the inlet of the drain pump 7, and the outlet of the drain pump 7 is connected to the condensate collection tank.

[0037] The second heat exchanger 4 enables heat exchange between the low-temperature airflow at the cold end of the vortex tube 1 and the water vapor, causing the water vapor to condense into liquid water, thus realizing the recovery and utilization of cold energy without the need for additional refrigeration equipment. The condensed liquid water is discharged from the system through the drain pump 7 and can be recycled as industrial or domestic water, improving the water resource utilization rate. At the same time, the condensation process of the second heat exchanger 4 further increases the temperature of the cold natural gas flow and also improves the temperature stability after the cold and hot air flows are mixed, ensuring the quality of downstream natural gas supply.

[0038] The inlet of the drain pump 7 is connected to the condensate outlet of the second heat exchanger 4. The drain pump 7 realizes the automatic discharge and collection of condensate. Preferably, the drain pump 7 is used in conjunction with a liquid level sensor, which can automatically start and stop according to the condensate level, further saving energy and ensuring the automation and intelligence of the system operation.

[0039] The combined process of the vortex tube and vacuum membrane distillation coupling system based on the utilization of residual pressure at natural gas gate stations according to the present invention specifically includes the following steps: Step 1: Gas source input and energy separation Natural gas from the high-pressure pipeline 2 enters the tangential inlet of the vortex tube 1 and is accelerated by the nozzle to form a high-speed vortex field. Adjusting the opening of the hot-end valve of the vortex tube 1 causes the airflow to be separated into layers, with the outer layer forming a high-temperature hot airflow and the inner layer forming a low-temperature cold airflow; the high-temperature hot airflow enters the tube side of the first heat exchanger 3, and the low-temperature cold airflow enters the tube side of the second heat exchanger 4.

[0040] Step 2: Material preheating The material delivery pump is started, and the material to be concentrated, flow 11, enters the shell side of the first heat exchanger 3 to exchange heat with the high-temperature hot gas flow, raising the material temperature. The preheated material then enters the liquid side of the VMD system 8. The high-temperature gas flow from the hot end of the vortex tube 1 sequentially enters the internal coil of the first heat exchanger 3 to exchange heat with the material to be concentrated flow 11 in the shell side. The hot-end gas flow after heat exchange continues to enter the main port of the ejector 10, preparing for subsequent pressure stabilization and mixing.

[0041] Step 3: Cold end airflow cooling and vacuum establishment steps The low-temperature airflow at the cold end of the vortex tube 1 enters the internal coil of the second heat exchanger 4 to provide cooling for water vapor condensation; at the same time, the vacuum pump 6 and valve 5 are turned on to evacuate the cold side of the VMD system 8 and the cavity of the second heat exchanger 4, so that a high vacuum environment is formed on the cold side, and the transmembrane vapor pressure difference required for membrane distillation is established.

[0042] Step 4: Vacuum membrane distillation and material concentration steps The material to be concentrated, after being preheated by the first heat exchanger 3, enters the hot side of the VMD system 8 and generates water vapor on the surface of the membrane 9. Under vacuum drive, the water vapor passes through the hydrophobic membrane 9 and enters the cold side of the VMD system 8. The material is trapped on the hot side and continuously dehydrated and concentrated, eventually forming a concentrated material that is discharged from the system.

[0043] Step 5: Water vapor condensation and condensate drainage Water vapor from the VMD system 8 through the side output enters the shell side of the second heat exchanger 4, where it exchanges heat with the low-temperature airflow at the cold end of the vortex tube 1 on the tube side, i.e., the surface of the coil, and quickly condenses into liquid water. The condensate collects at the bottom of the second heat exchanger 4 and is continuously discharged from the system by the drain pump 7, realizing water resource recovery.

[0044] Step 6: Dynamic Negative Pressure Maintenance and Energy-Saving Operation of Vacuum Pump When the vacuum level on the cold side of the second heat exchanger 4 and the VMD system 8 reaches the set value, valve 5 is closed and vacuum pump 6 stops working. The system relies on the condensation phenomenon of the sealed cavity to maintain dynamic negative pressure balance. Only when the pressure monitoring exceeds the upper limit, valve 5 is opened again and vacuum pump 6 is started to replenish the vacuum, so as to realize the intermittent operation of the vacuum pump and significantly reduce the power consumption of the system.

[0045] Step 7: Mixing and stabilizing hot and cold airflows and downstream gas supply steps After heat exchange, the hot-end airflow and cold-end airflow of the vortex tube 1 enter the main port and side port of the ejector 10, respectively, and are fully mixed within the ejector 10 to achieve temperature and pressure homogenization. The mixed medium-pressure natural gas is then stably output to the downstream pipeline network without affecting normal gas supply, completing the entire natural gas pressure regulation process. This specification and accompanying drawings are merely illustrative examples of this application and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Obviously, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Therefore, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A material concentration system based on vortex tubes and VMD systems, characterized in that, include: The vortex tube (1) is used to generate a cold end flow and a hot end flow when natural gas (2) enters its inlet end. The hot end of the vortex tube is connected to the first heat exchanger (3), and the cold end is connected to the second heat exchanger (4). The VMD system (8) is a vacuum membrane distillation assembly. Inside, a membrane (9) separates the feed side and the permeate side, with the permeate side being a negative pressure environment. The material to be concentrated (11) enters the first heat exchanger (3) to exchange heat with the hot end flow and be preheated. Then it enters the liquid side of the VMD system. Under the action of the transmembrane vapor pressure difference, the water in the material to be concentrated is evaporated and separated. Concentrated material is obtained on the liquid side, while steam is generated on the permeate side. The steam enters the second heat exchanger (4) to exchange heat with the cold end flow and is condensed to obtain liquid water. The hot end of the natural gas flows out from the first heat exchanger (3), and the cold end flows out from the second heat exchanger (4). The two flow together to form a pressure-regulated natural gas supply.

2. The material concentration system based on vortex tubes and VMD system according to claim 1, characterized in that, The first heat exchanger (3) and / or the second heat exchanger (4) are shell and tube heat exchangers.

3. The material concentration system based on vortex tubes and VMD system according to claim 1, characterized in that, Also includes: A vacuum pump (6) is connected in sequence to the cavity of the second heat exchanger (4) and the cold side of the VMD system (8) to establish a negative pressure environment on the cold side; Pressure sensor, used to monitor the negative pressure environment on the cold side; A valve (5) is located between the vacuum pump (6) and the second heat exchanger (4).

4. The material concentration system based on vortex tubes and VMD system according to claim 1, characterized in that, Also includes: A drain pump (7), which is connected to the second heat exchanger (4), is used to drain the liquid water formed by condensation.

5. The material concentration system based on vortex tubes and VMD system according to claim 1, characterized in that, Also includes: The hot end of the natural gas flows out from the first heat exchanger (3), and the cold end flows out from the second heat exchanger (4). The two flow into the downstream natural gas pipeline after merging at the ejector (10).

6. A material concentration method based on vortex tubes and a VMD system, characterized in that, include: Natural gas flow (2) enters vortex tube (1) to generate cold end flow and hot end flow. The hot end flow enters the first heat exchanger (3) and the cold end flow enters the second heat exchanger (4). The material to be concentrated (11) enters the first heat exchanger (3) to exchange heat with the hot end flow and is preheated, and then enters the liquid side of the VMD system (8); The permeate side of the VMD system (8) is a negative pressure environment. The water in the material to be concentrated on the feed side evaporates under the action of the transmembrane vapor pressure difference and enters the permeate side through the membrane (9) to generate steam. The steam enters the second heat exchanger (4) and exchanges heat with the cold end flow of the vortex tube, and after condensation, it becomes liquid water; After undergoing heat exchange, the cold and hot streams merge to form a pressure-regulated natural gas supply, which is then supplied to the downstream pipeline network.

7. A material concentration method based on vortex tubes and a VMD system, characterized in that, include: A negative pressure environment is established in the cavity of the second heat exchanger (4) and the through side of the VMD system (8) by a vacuum pump (6). When the negative pressure environment meets the requirements, the valve (5) between the vacuum pump (6) and the second heat exchanger (4) is closed, and the negative pressure environment on the cold side is monitored by a pressure sensor. When the negative pressure environment is not up to standard, open valve (5) and start vacuum pump (6) to establish a negative pressure environment in the cavity of the second heat exchanger (4) and the through side of VMD system (8).

8. A material concentration method based on vortex tubes and a VMD system, characterized in that, Also includes: The drainage pump automatically starts and stops based on the liquid water level detected by the level sensor in the second heat exchanger (4).

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