Tubular thermoelectric refrigeration multilayer film distillation assembly

Abstract

The invention belongs to the technical field of membrane distillation, and discloses a tubular thermoelectric refrigeration multilayer membrane distillation assembly. In view of the problems of complex pollutants, high treatment difficulty, low efficiency and high energy consumption of a traditional cooling mode, low heat efficiency of a partial membrane distillation mode and the like during waste liquid treatment in the existing membrane distillation technology, the assembly is designed to improve the membrane distillation efficiency and realize efficient conversion and clean utilization of the waste liquid. The assembly is mainly composed of two cover plates, a solar heat absorption layer, two membrane distillation devices and a liquid material mixing device, each membrane distillation device is divided into an outer side distillation device and an inner side distillation device, and all the components are cylindrical and are fixed through grooves in the cover plates. The construction of the hot side cavity and the cold side cavity ensures that the membrane distillation process is smooth, the hot side cavity is formed by a hydrophobic membrane, a solar heat absorption layer or the heat dissipation back face of an outer semiconductor refrigeration layer and a gasket, and the cold side cavity is formed by a gasket and a semiconductor refrigeration layer. The solar heat absorption layer heats liquid materials in the outer hot side cavity, the semiconductor refrigeration layer cools the cold side, and the liquid material mixing device mixes working media and utilizes heat on the back face of the semiconductor refrigeration layer. Compared with a traditional structure, the device is high in refrigeration efficiency, wide in cooling range and low in energy consumption, a polluted hydrophobic membrane is conveniently and independently replaced by adopting a thread fastening structure, the cost is reduced, and an efficient and economical solution is provided for waste liquid treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of membrane distillation, and in particular relates to a thermoelectric refrigeration air gap membrane distillation component with two hot sides, which can utilize clean energy and has a roll-type structure. Background Art

[0002] Industrial technology is constantly iterating and upgrading, and the waste liquid and solid waste generated have shown new characteristics, including an increase in the types of pollutants, complex and diverse characteristics, and increased difficulty in treatment. Among them, organic pollutants in waste liquids usually have high biological toxicity and are difficult to degrade, and their discharge into the environment will cause more significant harm and persistence. In addition, in actual engineering applications, traditional waste liquid treatment technologies often face problems such as low removal rate or high treatment cost. Therefore, there is an urgent need to develop a new, efficient and economical treatment technology.

[0003] Membrane distillation technology has received extensive attention in recent years due to its excellent separation performance and significant energy-saving potential. As an innovative separation method that combines thermodynamic distillation process with membrane separation technology, membrane distillation has been successfully applied to seawater desalination, brackish water treatment, and industrial wastewater concentration and desalination processes. This technology separates two solutions through a microporous hydrophobic membrane, using the vapor partial pressure difference caused by the temperature difference on both sides as the driving force, so that the volatile components in the high-temperature raw liquid pass through the hydrophobic membrane in gaseous form, while the liquid, insoluble substances and ions are effectively retained on one side of the raw liquid, thereby achieving the separation of volatile components and the concentration of the raw liquid.

[0004] Membrane distillation technology mainly includes four forms: direct contact, air gap, vacuum and air sweep. Among them, direct contact membrane distillation has become the most widely studied form due to its simple structure, convenient operation and large membrane flux, but its transmembrane heat conduction loss is large. Although air gap membrane distillation has been studied relatively less, it has attracted much attention because it has the highest thermal efficiency among the four basic forms.

[0005] Current membrane distillation modules usually rely on cold water circulation to achieve the cooling function of the cold side. Specifically, a refrigerator is needed to reduce the temperature of the cooling water to below 10°C and transport it to the cold side cavity of the membrane module through a pipeline. The cooling water circulates in the cavity to complete the cooling process. However, this cooling method has obvious shortcomings, including low cooling efficiency, significant cold loss during the cooling water circulation process, and high energy consumption of refrigeration equipment. Summary of the invention

[0006] In view of the above-mentioned defects of the existing membrane distillation technology, the present invention designs a tubular thermoelectric refrigeration multilayer membrane distillation component, striving to further improve the efficiency of membrane distillation, thereby achieving the goal of efficient conversion and clean utilization of waste liquid.

[0007] The tubular thermoelectric refrigeration multilayer membrane distillation assembly in the embodiment of the present invention mainly includes two cover plates, a solar heat absorption layer, two membrane distillation devices and a liquid material mixing device. Among them, the two membrane distillation devices are capable of independently completing the entire membrane distillation process, and they are located between the liquid material mixing device and the solar heat absorption layer. In order to ensure the accuracy and clarity of the description, the membrane distillation device is subdivided into an outer distillation device and an inner distillation device according to the position, and the cover plate is divided into an upper cover and a lower cover accordingly.

[0008] The distillation device and liquid-material mixing device are both composed of cylindrical components. The inner sides of the upper and lower covers are all provided with concentric grooves of different diameters. The diameters of the grooves can be precisely matched with the diameters of the components, thereby playing the function of fixing the components and effectively avoiding loosening and leakage of the components.

[0009] To ensure the smooth and complete implementation of the membrane distillation process, the hot side cavity, hydrophobic membrane and cold side cavity are indispensable, and they support the flow of hot liquid. As for the external distillation device, the hot side cavity is constructed by the gap between the hydrophobic membrane and the solar heat absorption layer in cooperation with the gasket. The inner side of the gasket fits tightly with the hydrophobic membrane, and the outer side fits tightly with the solar heat absorption layer. In this way, a cavity is built between the hydrophobic membrane and the solar heat absorption layer for the free flow of hot liquid, that is, the hot side cavity; and the cold side cavity is composed of a gasket and an external semiconductor refrigeration layer. The inner side of the gasket is closely connected to the semiconductor refrigeration layer, and the outer side is closely fitted with the hydrophobic membrane, and then a cavity is generated between the hydrophobic membrane and the semiconductor refrigeration layer, that is, the cold side cavity.

[0010] For the inner distillation component, the hot side cavity is constructed by the gap between the hydrophobic membrane and the heat dissipation back side of the outer semiconductor refrigeration layer with a gasket. The inner side of the gasket is tightly fitted with the hydrophobic membrane, and the outer side is tightly fitted with the heat dissipation back side of the outer semiconductor refrigeration layer, so that a cavity for the flow of hot liquid is formed between the hydrophobic membrane and the heat dissipation back side of the outer semiconductor refrigeration layer, that is, the hot side cavity; the cold side cavity is composed of a gasket and the inner semiconductor refrigeration layer. The inner side of the gasket is tightly fitted with the semiconductor refrigeration layer, and the outer side is tightly connected with the hydrophobic membrane, thereby forming a cold side cavity between the hydrophobic membrane and the semiconductor refrigeration layer.

[0011] Membrane distillation is achieved by relying on temperature difference. The outer hot side cavity relies on the solar heat absorption layer to increase the temperature of the liquid; the inner hot side cavity relies on the heat dissipation back of the outer semiconductor refrigeration layer to increase the temperature of the liquid. On the cold side of the air gap membrane distillation device, the low temperature is mainly reflected on the cold side copper plate. The present invention cleverly uses the semiconductor refrigeration layer to cool the cold side, ensuring that the hot side and the cold side of the device maintain a certain temperature difference to achieve membrane distillation.

[0012] The semiconductor refrigeration layer has significantly different characteristics at both ends under normal working conditions. One side has a lower temperature, called the cold end face, located on the outside of the semiconductor refrigeration layer; the other side has a higher temperature, called the heat dissipation face, located on the inside of the semiconductor refrigeration layer. The present invention closely fits the cold end faces of the inner and outer semiconductor refrigeration layers with the inner and outer hydrophobic films, respectively, to achieve effective cooling for the cold side cavity.

[0013] The liquid-material mixing device can fully mix the working fluid that has been heated and treated in the outer distillation device with the working fluid that has not been heated and is waiting to be treated in the outside. On the one hand, it can fully utilize the heat generated on the back side of the inner semiconductor refrigeration layer to improve the energy utilization efficiency; on the other hand, it can also achieve the heat dissipation effect of the semiconductor refrigeration layer with the help of liquid.

[0014] Compared to the traditional structure of using cooling water to directly cool the cold side, the present invention has a higher refrigeration efficiency of the semiconductor refrigeration layer, a wider cooling range, and lower energy consumption. The traditional device takes a long time to cool down, and the cooling range is limited. Especially when the temperature of the hot side is high, it is difficult for the cold side to be reduced to the ideal temperature due to its interference. In addition, the traditional device has extremely strict requirements for cold water, and it is necessary to use a refrigerator to take very low temperature water before it can be put into use, and the refrigerator consumes a lot of energy. In contrast, in the present invention, the role of cold water is only to cool the semiconductor refrigeration layer, and it does not directly participate in the membrane distillation process. Therefore, the requirements for cold water are not high, and there is no need to use a refrigerator for pre-cooling.

[0015] Compared with the authorized invention patents related to the roll membrane distillation component, the present invention has significant innovation. In terms of energy utilization, the present invention sets a solar heat absorption layer on the outer shell of the component, which has efficient solar energy conversion and absorption performance, can efficiently convert the absorbed solar energy into thermal energy, and directly act on the liquid in the hot side cavity. At the same time, the characteristic that the inner side of the semiconductor refrigeration layer needs to dissipate heat is cleverly utilized, and the recovered heat is used to heat the liquid. In the layout of the entire component, the coordination between the components enables the heat to be fully recycled within the system, thereby improving the energy utilization efficiency. In terms of liquid material processing, the present invention designs a liquid material mixing device at the center of the component. During operation, the device can fully mix the working fluid treated by the outer distillation device and the working fluid that has not been treated in the outside world, thereby realizing the secondary membrane distillation of the liquid and achieving the goal of efficient conversion of the waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional schematic diagram of the overall structure;

[0017] Figure 2 It is a partial enlarged view of the overall structure;

[0018] Figure 3 It is a schematic diagram of the upper cover structure;

[0019] Figure 4 It is a schematic cross-sectional view of a local upper cover;

[0020] Figure 5 It is a schematic diagram of the structure of the local solar heat absorption layer;

[0021] Figure 6 Schematic diagram of the gasket structure;

[0022] Figure 7 It is a schematic diagram of the semiconductor refrigeration layer structure;

[0023] Figure 8 Schematic diagram of the lower cover structure.

[0024] As shown in the figure: 1. Upper cover, 1-1. Upper cover shell, 1-1-1. Upper inner thread, 1-2. External hot side water inlet, 1-3. External hot side water outlet, 1-4. Liquid material mixing device water outlet, 1-5. Liquid material mixing device hot side water inlet, 1-6. Liquid material mixing device cold side water inlet, 1-7. Internal hot side water inlet, 1-8. Internal hot side water outlet, 1-9. Liquid-material mixing layer, 2. Solar energy heat absorption layer, 2-1. Solar energy heat absorption layer shell, 2-2. Upper external thread, 3. Outer filter membrane, 4. Inner filter membrane, 5. Outer gasket one, 6. Outer gasket two, 7. Inner gasket one, 8. Inner gasket two, 9. Outer semiconductor refrigeration layer, 9-1 Semiconductor layer shell, 9-2. Refrigeration semiconductor particles, 10. Inner semiconductor refrigeration layer, 11. Outer hydrophobic membrane, 12. Inner hydrophobic membrane, 13. Lower cover, 13-1. Lower cover shell, 13-2. Outer cooling side water outlet, 13-3 Inner cooling side water outlet. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solutions and advantages of the present invention, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0026] Example:

[0027] The present invention provides a tubular thermoelectric refrigeration multilayer membrane distillation component. The component is characterized in that the component has two hot side cavities and two cold side cavities. Figure 1As shown, the outer shell of the component is composed of an upper cover 1, a solar heat absorption layer 2 and a lower cover 12. In the outer shell, the solar heat absorption layer 2, the outer filter membrane 3, the outer gasket 1 5, the outer gasket 2 6, and the outer hydrophobic membrane 11 form an outer hot side cavity; at the same time, the outer cold side cavity composed of the outer filter membrane 3 and the outer semiconductor refrigeration layer 9 is used to realize the first complete membrane distillation process. At the same time, the inner hot side cavity is composed of the inner filter membrane 4, the inner gasket 1 7, the inner gasket 2 8, the inner side of the outer semiconductor refrigeration layer 9 and the inner hydrophobic membrane 12; at the same time, the inner cold side cavity composed of the inner filter membrane 4 and the inner semiconductor refrigeration layer 10 is used to realize the second complete membrane distillation process. In addition, semiconductor refrigeration is used on the cold side of the outer distillation device in this component. In the central area of ​​the component, the liquid-material mixing layer 1-9 and the lower cover 13 are used to form a liquid-material mixing device.

[0028] As shown in Figure 4, the inner side of the upper cover 1 is provided with an internal thread 1-1-1, which has strict size adaptability with the external thread 2-2 on the upper side of the shell, and can be precisely tightened by rotating the thread to build a stable sealed connection, blocking the outside from communicating with the internal cavity. Correspondingly, the inner side of the lower cover 13 is designed in a standardized manner, and is equipped with an internal thread that is consistent with the key parameters such as specifications, pitch, and tooth angle of the internal thread of the upper cover, and can be tightened with the external thread of the same specification on the lower part of the shell. After the invention design, after reserving the water inlet and outlet, the device is assembled into a box structure with good sealing performance. This sealing performance prevents internal liquid leakage and blocks the intrusion of impurities, creating a reliable environment for the stable operation of the internal system and ensuring the efficient and orderly progress of membrane distillation.

[0029] Since the tubular thermoelectric refrigeration multilayer membrane distillation component adopts a threaded fastening structure, when the outer hydrophobic membrane 11 or the inner hydrophobic membrane 12 in the component is contaminated, affecting the distillation effect and efficiency, the hydrophobic membrane can be replaced separately to save production costs.

[0030] The solar heat absorption layer 2 has excellent solar energy conversion and absorption performance, and can efficiently convert the absorbed solar energy into heat energy, and then directly act on the liquid in the external heat side cavity to achieve rapid heating. In this process, heat is transferred from the solar heat absorption layer 2 to the liquid by conduction. Due to the short conduction path and low thermal resistance, heat loss is greatly reduced, so that energy utilization efficiency can be significantly improved.

[0031] Semiconductor refrigeration is an important refrigeration method, also known as electronic refrigeration or thermoelectric refrigeration. Its working principle is based on the PN junction constructed by special semiconductor materials. When the current passes through the thermocouple pair composed of these PN structures, it will induce the Peltier effect, thereby realizing the directional migration and transfer of heat. This is an innovative refrigeration technology that directly achieves the refrigeration effect with the help of direct current. In the membrane distillation process, maintaining a low temperature on the cold side is one of the key factors to ensure the distillation effect. Traditional membrane distillation components usually rely on refrigerators to produce low-temperature cold water, and then circulate the cold water continuously in the cold side cavity to achieve the purpose of lowering the temperature of the cold side. However, this method has problems such as high energy consumption of refrigeration equipment, low cooling efficiency, and obvious loss of cold during the circulation process.

[0032] The present invention innovatively uses a semiconductor refrigeration layer to achieve the cooling operation on the cold side, effectively overcoming the shortcomings of the traditional method. By precisely integrating the semiconductor refrigeration layer into the membrane distillation component and utilizing its unique refrigeration characteristics, a stable and efficient cooling effect is provided for the cold side, thereby ensuring that the membrane distillation process proceeds smoothly under a suitable temperature difference.

[0033] At the basic principle level, the semiconductor refrigeration layer plays the role of a heat transfer medium. Specifically, when current flows through the semiconductor refrigeration layer, a directional migration of heat will be induced between its two end faces, and the heat will flow from one end to the other end, thereby causing a temperature difference to form, defining the cold end and the hot end. Among them, the cold end face with a reduced temperature will come into contact with the liquid inside the cold side cavity, achieving an effective reduction in the cold side temperature during the membrane distillation process. In order to ensure that the semiconductor refrigeration layer can maintain a long-term and efficient operating state, under the design framework of the present invention, the hot end face of the outer semiconductor refrigeration layer is contacted with the liquid in the inner hot side cavity; the hot end face of the inner semiconductor refrigeration layer is in contact with the liquid in the liquid-material mixing device, which, on the one hand, achieves the purpose of cooling the hot end of the semiconductor refrigeration plate, and on the other hand, achieves the effect of heat recovery, and then uses the recovered heat to provide heating energy for the liquid in the hot side cavity.

[0034] The upper cover 1 and the lower cover 13 are both provided with grooves with a depth of 5 mm that match the diameter of each component. On the one hand, they can fix the position of each component to prevent the components from shifting during the membrane distillation process; on the other hand, they can isolate the liquid materials inside and outside the components to avoid mixing of the liquid materials on both sides, reduce the temperature difference, and affect the distillation effect.

[0035] In the aforementioned liquid material mixing device composed of the liquid material mixing layer 1-9 and the lower cover 13, the once treated liquid material passing through the external hot side cavity and the external liquid material to be treated enter the cavity through the hot side water inlet 1-5 of the liquid material mixing device and the cold side water inlet 1-6 of the liquid material mixing device respectively. During the liquid material mixing process, the liquid material mixing layer 1-9 plays the role of isolating the water inlet of the device and the water outlet 1-4 of the liquid material mixing device, so as to fully mix the two liquid materials and evenly distribute the heat in the liquid materials.

[0036] like Figure 6 As shown, the gasket is specially provided with an opening structure in its structural design. When the liquid enters the cavity from the water inlet, the liquid contained in the cavity is immediately diverted and flows in two directions, the inside and the outside of the gasket. In this process, if there is a temperature difference in the liquid in the cavity, due to the fluidity of the liquid itself and the guiding effect of the gasket opening, the liquid will continue to be in a flocculent state inside the cavity, and can pass through the gasket opening, so as to achieve the mutual flow and mixing between the liquids on both sides of the gasket, and achieve the effect of evenly distributing heat to the liquid in the entire cavity, ensuring the balance of temperature distribution in the cavity, and improving the thermal stability and operation efficiency of the overall system.

[0037] To more clearly illustrate the structure of the membrane distillation module of the present invention, Figure 1 The working process of the membrane distillation device is described.

[0038] The inner sides of the upper cover 1 and the lower cover 13 are provided with grooves with the diameter of each component and a depth of 5 mm, and the inner semiconductor layer 10, the inner hydrophobic membrane 12, the inner gasket 2 8, the inner filter membrane 4, the inner gasket 1 7, the outer semiconductor refrigeration layer 9, the outer hydrophobic membrane 11, the outer gasket 2 6, the outer filter membrane 3, the outer gasket 1 5, and the solar heat absorption layer 1 are installed respectively from the inside to the outside. The external threads at the upper and lower ends of the solar heat absorption layer 1 are screwed together with the internal threads of the upper and lower covers to combine the components together.

[0039] The working fluid to be treated enters the hot side cavity through the external hot side water inlet 1-2, and the solar energy heat absorption layer directly heats the liquid. At the same time, the liquid passes through the external filter membrane 3, first filters out impurities with large particle diameters, and enters the outside of the external hydrophobic membrane 11. At the same time, the external semiconductor refrigeration layer 9 continues to cool the external cold side cavity. When the hot side and the cold side reach a certain temperature difference, part of the water in the hot side cavity passes through the external hydrophobic membrane 11 in the form of water vapor, and condenses on the external hydrophobic membrane 11 to realize the first membrane distillation process. Between the external hydrophobic membrane 11 and the external filter membrane 3, part of the heated liquid passes through the hot side water inlet 1-5 of the liquid-material mixing device through an external pipeline, and is fully mixed with the working fluid to be treated from the outside in the liquid-material mixing device. During the mixing process, the inner side of the internal semiconductor refrigeration layer 10 dissipates heat, and the heat is absorbed by the liquid, thereby realizing heating and energizing the liquid. When the liquid material fills the liquid material mixing device, it passes through the water outlet 1-4 of the liquid material mixing device, and is connected to the inner hot side water inlet 1-7 through a pipeline, and enters the inner hot side cavity. The liquid material contacts the inner side of the outer semiconductor refrigeration layer 9 in the inner hot side cavity, and the liquid material temperature is increased again, thereby increasing the temperature difference and improving the distillation efficiency. The second distillation process is exactly the same as the first distillation process, and will not be described in detail here.

Claims

1. A tubular thermoelectric refrigeration multilayer membrane distillation component, the membrane distillation component includes an upper cover, a lower cover, two membrane distillation devices and a liquid material mixing device, the liquid material mixing device is in the center position, the two membrane distillation devices are discharged outward in sequence, and the upper cover and the lower cover are respectively located at the upper end and the lower end of the component.

2. The membrane distillation assembly according to claim 1, characterized in that: The membrane distillation device is composed of two gaskets, a filter membrane, a hydrophobic membrane and a semiconductor refrigeration layer; The semiconductor refrigeration layer is at the innermost side of the membrane distillation component; the hydrophobic membrane is located on the outer side of the semiconductor refrigeration layer, that is, on the side of the cold end face; a filter membrane is placed between the two gaskets, located on the outer side of the hydrophobic membrane; the cavity between the hydrophobic membrane and the inner side of the solar heat absorption layer or the semiconductor refrigeration layer is the hot side cavity, and the cavity between the hydrophobic membrane and the outer side of the semiconductor refrigeration layer is the cold side cavity.

3. The membrane distillation assembly according to claim 1, characterized in that: The upper cover is composed of a shell, a liquid-material mixing layer, an outer hot side water inlet, an outer hot side water outlet, a liquid-material mixing device water outlet, a liquid-material mixing device hot side water inlet, a liquid-material mixing device cold side water inlet, an inner hot side water inlet, and an inner hot side water outlet; An internal thread is provided on the inner side of the shell, which can be screwed together with the external thread of the solar heat absorption layer; the external hot side water inlet and the external hot side water outlet are both connected to the external hot side cavity; the internal hot side water inlet and the internal hot side water outlet are both connected to the internal hot side cavity; the liquid-material mixing device water outlet, the hot side water inlet of the liquid-material mixing device, and the cold side water inlet of the liquid-material mixing device are all connected to the liquid-material mixing device; all the water inlets and water outlets protrude upward and have the same opening size.

4. The membrane distillation assembly according to claim 1, characterized in that: The lower cover is composed of a lower cover shell, an outer cooling side water outlet, and an inner cooling side water outlet; An internal thread is provided on the inner side of the lower cover shell, which can be screwed together with the external thread of the solar heat absorption layer; the outer cooling side water outlet is connected to the outer cooling side cavity; the inner cooling side water outlet is connected to the inner cooling side cavity; the outer cooling side water outlet and the inner cooling side water outlet are both protruding upward and have the same opening size.

5. The membrane distillation assembly according to claim 1, characterized in that: The liquid-material mixing device is composed of a liquid-material mixing layer and a lower cover.

6. The membrane distillation assembly according to claim 2, characterized in that: The gasket is provided with an opening.

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