A boundary membrane purification apparatus and purification method for vapours

Abstract

The application discloses a kind of membrane interface purification device and purification method of steam, wherein the membrane interface purification device of steam, comprising: container, it is equipped with container cavity in;Interface membrane component, it is equipped in the container cavity and is connected with the container, the interface membrane component can fill the liquid of condensable vapor in the container cavity, the liquid level of the liquid of condensable vapor will the container cavity be divided into import end and export end, the import end is communicated with mixed gas import, and the export end is communicated with steam export.The liquid of condensable vapor can absorb steam, using the phase change of steam, so that steam can pass through the liquid of condensable vapor, and non-condensable impurity gas is difficult to pass through the liquid of condensable vapor, to realize the separation of steam and non-condensable impurity gas, i.e.to realize the purification treatment of steam.

Description

Technical Field

[0001] This invention relates to the field of steam purification technology, and in particular to a vapor membrane purification apparatus and method. Background Technology

[0002] Steam has a high enthalpy, which can rapidly raise the temperature of materials, making it widely used as a heat energy medium in various industrial production fields. For example, large amounts of steam are needed in processes such as foam molding steam heating and papermaking. Many large-scale enterprises can build their own steam boilers to supply their own saturated steam.

[0003] However, during the production and use of steam, non-condensable impurity gases are often mixed in. These non-condensable impurity gases have lower condensation temperatures than the steam itself, and they are less soluble in the liquid phase of the steam. Examples include air in water vapor, methane in ethane vapor, and methane in methanol vapor. The presence of these impurity gases affects the purity and quality of the steam, thus impacting subsequent processes and leading to uncontrollable factors. Therefore, improving the purity of the steam is crucial. For instance, during use, the heat exchange efficiency of water vapor containing non-condensable air will be significantly reduced. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] In a first aspect, the present invention provides a vapor boundary membrane purification device, comprising: a container having a cavity therein; a boundary membrane assembly disposed in the cavity and connected to the container, the boundary membrane assembly being able to fill the cavity with a liquid capable of condensing vapor, the liquid surface of the liquid capable of condensing vapor dividing the cavity into an inlet end and an outlet end, the inlet end being connected to a mixed gas inlet, and the outlet end being connected to a vapor outlet.

[0006] According to an embodiment of the present invention, a vapor boundary membrane purification device has at least the following beneficial effects: A container is provided with a cavity, and a boundary membrane assembly is connected to the container and disposed within the cavity. Under the action of the boundary membrane assembly, a liquid containing condensable vapor can be filled into the cavity. The liquid containing condensable vapor and the vapor are different states of the same substance. The liquid surface separation of the condensable vapor divides the cavity into an inlet end and an outlet end. In use, the user can introduce vapor mixed with non-condensable impurities into the inlet end from the mixed gas inlet. The pressure at the inlet end is greater than the pressure at the outlet end. In the initial stage, the temperature of the boundary membrane assembly is lower than the temperature of the mixed gas. The condensable vapor releases heat and condenses on the boundary membrane assembly to form a liquid. Since the vapor and the liquid containing condensable vapor are the same substance, the vapor can release heat and condense on the liquid containing condensable vapor. At the surface of the liquid, the condensable vapor can absorb the vapor from the mixed gas. At the surface of the condensable vapor liquid, the condensable vapor liquid can absorb the heat of the liquid and reform vapor. In other words, macroscopically, by utilizing the phase change of vapor, vapor can pass through the condensable vapor liquid and enter from the inlet to the outlet. However, due to the low solubility of impurity gases in the condensable vapor liquid, the impurity gases are greatly restricted from passing through the condensable vapor liquid due to the barrier effect of the condensable vapor liquid. In other words, macroscopically, impurity gases cannot pass through the condensable vapor liquid, thereby achieving the separation of vapor and impurity gases, and thus achieving vapor purification. Under the purification effect of this vapor boundary membrane purification device, it is beneficial to improve the purity of the vapor so that the vapor can meet the application requirements of various processes. The structure is simple and the process controllability is higher.

[0007] According to some embodiments of the present invention, the membrane assembly includes a membrane substrate connected to the inner wall of the cavity, the membrane substrate having perforations, and the membrane substrate being used to attach a condensable vapor liquid to form a condensable vapor liquid film.

[0008] Specifically, the membrane assembly includes a membrane substrate, which is connected to the inner wall of the cavity. The membrane substrate provides support for the condensable vapor liquid, allowing the condensable vapor liquid to form a condensable vapor liquid film at the membrane substrate. The liquid film is automatically distributed at the perforations, meaning it is continuous and uninterrupted. The perforations facilitate the transfer of heat from one side of the liquid film to the other side, allowing the heat released by vapor condensation to quickly pass through the perforations and be converted into heat absorbed by the evaporation of the condensable vapor liquid. This achieves energy balance, material balance, and force balance on both sides of the liquid film, maintaining its continuity.

[0009] According to some embodiments of the present invention, the inlet end and the outlet end are located on the left and right sides of the membrane substrate, respectively, and both the inlet end and the outlet end are opposite to the perforation.

[0010] Specifically, the inlet and outlet are located on the left and right sides of the membrane substrate, respectively. The membrane substrate is located in the middle of the container, and a liquid film of condensable vapor is attached to the membrane substrate. Under the barrier effect of the liquid film, the cavity is divided into the inlet and outlet. Under the barrier effect of the liquid film, the mixed gas can be separated from the vapor and the non-condensable impurity gas, that is, the vapor is purified. The inlet and outlet are opposite to the perforations. When the vapor condenses, the heat released can pass through the perforations and be transferred to the other surface of the liquid film, so that the liquid of condensable vapor can absorb heat and re-evaporate, which is beneficial to improving the heat transfer efficiency.

[0011] According to some embodiments of the present invention, the membrane assembly further includes a liquid compensator containing a condensable vapor liquid, the liquid compensator being connected to the membrane substrate to allow the condensable vapor liquid to flow to the membrane substrate and form a liquid film.

[0012] The interfacial membrane assembly also includes a liquid compensator, which contains a liquid capable of condensing vapors and is connected to the membrane substrate. The liquid compensator can replenish the liquid capable of condensing vapors onto the membrane substrate. After the membrane substrate adsorbs the liquid capable of condensing vapors, under the action of interfacial forces between the liquid molecules and the solid interface, the liquid capable of condensing vapors can adhere to the surface of the membrane substrate, thereby forming a liquid film capable of condensing vapors. This liquid film can block non-condensable impurity gases, and the vapor can pass through the liquid film to enter the outlet end, thereby achieving vapor purification treatment.

[0013] According to some embodiments of the present invention, the inlet end is also connected to an outlet for impurity gas.

[0014] Specifically, the inlet end is also connected to an impurity gas outlet. Through the impurity gas outlet, the non-condensable gas blocked by the liquid film can be discharged from the inlet end, thereby increasing the vapor concentration in the inlet end, increasing the mass and heat transfer rate between the vapor and the liquid film, thereby increasing the vapor flow rate, and helping to control the pressure at the inlet end, thus avoiding the problem of excessive pressure difference between the inlet end and the outlet end, which could lead to a gap in the liquid film.

[0015] According to some embodiments of the present invention, the cavity contains a liquid that can condense vapor, the outlet end is located above the liquid surface of the liquid that can condense vapor, the inlet end is located below the liquid surface of the liquid that can condense vapor, the membrane substrate is immersed in the liquid that can condense vapor, and the inlet end also includes an impurity gas outlet, both of which are located below the membrane substrate.

[0016] The outlet and inlet are arranged vertically, with the outlet filled with a liquid that can condense vapors. The membrane substrate is positioned below the surface of the liquid that can condense vapors, and both the mixed gas inlet and the impurity gas outlet are located below the membrane substrate. When the mixed gas is introduced into the inlet from the mixed gas inlet, the mixed gas comes into full contact with the liquid that can condense vapors, and the vapors can condense in the liquid that can condense vapors and move upward through the membrane substrate, so that the surface of the liquid that can condense vapors can absorb heat and re-evaporate. Meanwhile, the non-condensable impurity gas is discharged from the inlet from the impurity gas outlet, thereby achieving the separation of vapors and non-condensable impurity gases.

[0017] According to some embodiments of the present invention, the membrane substrate is tubular, with the mixed gas inlet and the impurity gas outlet respectively opposite to the two ends of the membrane substrate; or, the membrane substrate is planar; or, the membrane substrate is arc-shaped.

[0018] Optionally, the membrane substrate is tubular, with the mixed gas inlet and impurity gas outlet positioned opposite each other at its two ends. The mixed gas enters the tubular membrane substrate through the inlet, allowing vapor to condense in a condensable liquid. This condensable liquid absorbs the vapor from the mixed gas, while the non-condensable impurity gas exits from the impurity gas outlet. This avoids excessive pressure difference between the inlet and outlet, which could lead to liquid film damage. Alternatively, the membrane substrate can be planar, allowing the mixed gas to enter through the inlet. After the mixed gas enters the inlet, the bubbles can move upward, the vapor condenses in the liquid that can condense vapor, while the impurity gas continues to move upward and, guided by the membrane substrate, is discharged from the inlet through the impurity gas outlet, thus achieving the separation of vapor and impurity gas. Optionally, the membrane substrate is arc-shaped. When the mixed gas enters the inlet from the mixed gas inlet, the bubbles can move upward, the vapor condenses in the liquid that can condense vapor, while the impurity gas continues to move upward and, guided by the membrane substrate, is discharged from the inlet through the impurity gas outlet, thus achieving the separation of vapor and impurity gas.

[0019] According to some embodiments of the present invention, the film substrate is provided with a plurality of perforations, which are arranged in a close arrangement.

[0020] The membrane substrate has multiple perforations arranged in a close arrangement, meaning the membrane substrate is made of a highly permeable material. The liquid that can condense vapor can fill the multiple perforations, forming a continuous and uninterrupted liquid film. The close arrangement of perforations enhances the heat transfer of the membrane substrate, allowing heat to be transferred from one end of the liquid film to the other. This allows the heat released by vapor condensation to be converted into the heat absorbed by the evaporation of the liquid film, thus achieving energy balance, material balance, and force balance on both sides of the liquid film to maintain its continuity.

[0021] According to some embodiments of the present invention, the present invention further includes a support, wherein the membrane substrate and the inner wall surface of the cavity are both connected to the support to fix the relative positional relationship between the membrane substrate and the cavity; and / or,

[0022] The membrane substrate is a metal mesh, fiber cloth, or polymer mesh cloth; and / or,

[0023] The liquid film is a water film.

[0024] Optionally, the vapor interfacial membrane purification device also includes a support. During use, the support can be connected to the inner wall of the cavity, and the membrane substrate can be fixed to the support, thus enabling the membrane substrate to connect with the inner wall of the cavity. The support can fix the relative position of the membrane substrate and the container, thereby preventing the membrane substrate from shaking due to the impact of the mixed gas, and ensuring the barrier against non-condensable impurities. Optionally, the membrane substrate can be a metal mesh, fiber cloth, or polymer mesh. The surface of the membrane substrate has multiple closely arranged perforations, providing good air permeability to meet the requirements of heat transfer and improving the efficiency of vapor purification. Optionally, specifically, when it is necessary to remove non-condensable air from water vapor, the liquid film can be a water film. When water vapor comes into contact with the liquid film, the liquid film can absorb the water vapor, while the solubility of non-condensable air is low, allowing the water vapor to pass through the liquid film for purification.

[0025] In a second aspect, the present invention also provides a purification method applied to the vapor purification apparatus shown in the first aspect, comprising the following steps:

[0026] The membrane substrate is connected to the inner wall of the cavity, and a liquid film is formed on the membrane substrate, allowing the mixed gas to be introduced into the inlet end from the mixed gas inlet.

[0027] With the radius of the perforation as r, the surface tension coefficient of the liquid film as σ, the pressure at the inlet end as P1, and the pressure at the outlet end as P2, the pressure difference between the inlet end and the outlet end is controlled so that P1-P2≤2σ / r, and the liquid film can be continuously and uninterruptedly attached to the film substrate.

[0028] Steam is collected at the outlet end through the steam outlet.

[0029] According to an embodiment of the present invention, a purification method has at least the following beneficial effects: Before introducing the mixed gas, a membrane substrate is attached to the inner wall of the cavity, and a liquid film of condensable vapor is formed on the membrane substrate. Then, vapor mixed with non-condensable impurities is introduced into the inlet end from the mixed gas inlet. The pressure difference between the inlet end and the outlet end is controlled. According to the pressure balance formula of liquid, the liquid film is continuously and uninterruptedly adsorbed on the membrane substrate. Under the barrier effect of the liquid film, since the vapor and the liquid of condensable vapor are the same substance, the vapor can release heat and condense in the liquid of condensable vapor. That is, the liquid of condensable vapor can absorb the vapor in the mixed gas, while the liquid of condensable vapor can absorb the vapor in the mixed gas. At the surface of the liquid vapor, the liquid vapor that can condense vapor absorbs the heat released by the vapor liquefaction and reforms into vapor. In other words, macroscopically speaking, by utilizing the phase change of vapor, vapor can pass through the liquid vapor that can condense vapor and enter the outlet from the inlet. However, due to the low solubility of impurity gases in the liquid vapor that can condense vapor, the impermeability of the liquid vapor greatly restricts the passage of impurity gases through the liquid vapor that can condense vapor. In other words, macroscopically speaking, this achieves the separation of vapor from non-condensable impurity gases, thereby purifying the vapor. Under the purification effect of this vapor boundary membrane purification device, it is beneficial to improve the purity of the vapor so that the vapor can meet the application requirements of various processes and the process controllability is higher.

[0030] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 A structural diagram of a vapor interfacial membrane purification device provided in an embodiment of the present invention;

[0033] Figure 2 A structural diagram illustrating the connection between the membrane assembly and the container in a vapor membrane purification apparatus according to an embodiment of the present invention;

[0034] Figure 3 This is a structural diagram of a vapor boundary membrane purification apparatus provided for other embodiments of the present invention.

[0035] Figure label:

[0036] 100. Container; 110. Cavity; 111. Inlet end; 112. Outlet end; 113. Mixed gas inlet; 114. Impurity gas outlet; 115. Steam outlet; 200. Membrane module; 210. Membrane substrate; 211. Perforation; 220. Support. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0039] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or," "and / or," or "and / or" throughout the text implies three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0040] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0041] The following is for reference. Figures 1 to 3 According to an embodiment of the present invention, a vapor boundary membrane purification apparatus and method are provided. The absorption of vapor from a mixed gas by a condensable vapor liquid utilizes the phase change of the vapor—that is, the process of vapor changing from a gaseous state to a liquid state and then from a liquid state to a gaseous state—allowing the vapor to pass through the condensable vapor liquid. Since impurity gases have very low solubility in condensable vapors, they are blocked by the condensable vapor liquid, thereby achieving vapor purification. For example, this vapor boundary membrane purification apparatus can be used to remove air from water vapor, methane from ethane vapor, methane from methanol vapor, etc.

[0042] Example 1, as can be understood, see [link to example]. Figure 1 and Figure 2 According to an embodiment of the present invention, a vapor boundary membrane purification device includes a container 100 and a boundary membrane assembly 200. The container 100 has a cavity 110. The container 100 can be a tube, a column, a cuboid, etc., which are only examples for illustration and the shape and specifications of the container 100 are not limited in practice.

[0043] A boundary membrane assembly 200 is disposed within the cavity 110 and connected to the inner wall surface of the cavity 110. The boundary membrane assembly 200 can form a condensable vapor liquid film within the cavity 110, dividing the cavity 110 into an inlet end 111 and an outlet end 112 by the liquid film. See also Figure 1 The following explanation uses the example of the inlet end 111 and the outlet end 112 being arranged side by side. The liquid film can be arranged in a vertical plane, that is, the inlet end 111 and the outlet end 112 are located on the left and right sides of the liquid film, respectively.

[0044] The inlet end 111 is provided with a mixed gas inlet 113 and an impurity gas outlet 114, both of which are connected to the inlet end 111. The outlet end 112 is provided with a steam outlet 115, and the outlet end 112 is connected to the steam outlet 115.

[0045] In use, the user can introduce vapor mixed with non-condensable impurity gas into the inlet end 111 from the mixed gas inlet 113. The pressure at the inlet end 111 is greater than the pressure at the outlet end 112. Since the vapor and the condensable vapor liquid are different states of the same substance, the vapor can release heat and condense in the condensable vapor liquid. That is, the condensable vapor liquid can absorb the vapor in the mixed gas. On the other surface of the condensable vapor liquid, the condensable vapor liquid can absorb the heat of the liquid and reform vapor. In other words, macroscopically speaking, by utilizing the phase change of vapor, the vapor can pass through the condensable vapor liquid and enter the outlet end 112 from the inlet end 111. However, since the impurity gas has very low solubility in the condensable vapor liquid, the impurity gas is greatly restricted from passing through the condensable vapor liquid due to the barrier effect of the condensable vapor liquid. In other words, macroscopically speaking, the impurity gas cannot pass through the condensable vapor liquid, thus achieving the separation of vapor and non-condensable impurity gas.

[0046] Specifically, the liquid that can condense vapor can absorb the heat released by the condensation of vapor to achieve re-vaporization and form vapor. In other words, macroscopically, vapor can pass through the liquid film. When in equilibrium, the heat released by the condensation of vapor is the same as the heat absorbed by the vaporization of liquid that can condense vapor, so that the vapor in the mixed gas can enter the outlet 112 from the inlet 111 and be discharged from the vapor outlet 115 at the outlet 112.

[0047] For non-condensable impurity gases in the mixed gas, since the solubility of non-condensable impurity gases in the liquid film is very low, the resistance of the liquid film greatly restricts the passage of non-condensable impurity gases through the liquid film. In other words, macroscopically, non-condensable impurity gases cannot pass through the liquid film, causing them to remain in the inlet end 111. This achieves the separation of vapor and non-condensable impurity gases, thereby purifying the vapor. Under the purification effect of this vapor boundary membrane purification device, it is beneficial to improve the purity of the vapor, so that the vapor can meet the usage requirements of various processes, and the process controllability is higher.

[0048] The inlet end 111 is also connected to the impurity gas outlet 114. Through the impurity gas outlet 114, the non-condensable impurity gas blocked by the liquid film can be discharged from the inlet end 111, thereby increasing the vapor concentration in the inlet end 111, increasing the mass and heat transfer rate between the vapor and the liquid film, thereby increasing the vapor flow rate, and helping to control the pressure of the inlet end 111, thereby avoiding the problem of excessive pressure difference between the inlet end 111 and the outlet end 112, which could lead to a gap in the liquid film.

[0049] It is understood that, in order to form a liquid film within the cavity 110, the interfacial membrane assembly 200 includes a membrane substrate 210, which can be connected to the inner wall surface of the cavity 110, see [reference]. Figure 1 The membrane substrate 210 is arranged in a vertical plane. The inlet end 111 and the outlet end 112 are located on the left and right sides of the membrane substrate 210, respectively. The membrane substrate 210 is provided with a perforation 211, and the inlet end 111 and the outlet end 112 are both arranged opposite to the perforation 211.

[0050] The membrane substrate 210 is used to adsorb condensable vapor liquid and to provide support for the liquid film. The solid mainly supports the liquid film through interfacial forces, such as intermolecular forces, electrostatic attraction, and even chemical bond forces. Specifically, the attraction of solid molecules to liquid molecules includes van der Waals forces, wetting, capillary forces, etc., so that the condensable vapor liquid forms a condensable vapor liquid film on the membrane substrate 210. Under natural conditions, the perforations 211 on the membrane substrate 210 can be connected to the inlet end 111 and the outlet end 112. When the condensable vapor liquid flows to the membrane substrate 210 to form a liquid film, under the action of liquid surface tension, the liquid can fill the perforations 211 of the membrane substrate 210. The perforations 211 are designed to facilitate the transfer of heat from one side of the liquid film to the other side, thereby reducing or avoiding the blocking effect of the membrane substrate 210 on heat.

[0051] After the vapor condenses on the left side of the liquid film, the liquid film can absorb heat on the right side and reform vapor, so that the vapor can pass through the liquid film, thereby improving the permeability of the film substrate 210 to the vapor.

[0052] Assuming the gases filling the left and right sides of the liquid film are both saturated vapors, and since the vapor pressure on the left side of the liquid film is greater than that on the right side, according to the correlation between boiling point and pressure, the higher the pressure, the higher the boiling point, and vice versa. Let the vapor boiling point on the left side of the liquid film be T1 and the pressure be P1, and the vapor boiling point on the right side be T2 and the pressure be P2, with T1 ≥ T2. When the system is in equilibrium, the temperature of the liquid film is between T1 and T2. According to the pressure balance formula for liquids: P1 - P2 ≤ 2σ / r, where σ is the surface tension coefficient of the liquid film and r is the principal radius of curvature of the interfacial droplets. Neglecting gravity, then P1 - P2 = 2σ / r. Therefore, the mass of vapor condensed on the left side of the liquid film is equal to the mass of vapor evaporated on the right side.

[0053] The heat released by the condensation of vapor can pass through the perforation 211 and be quickly transferred to the other surface of the liquid film, thus being converted into the heat absorbed by the evaporation of the liquid film, so that evaporation can be completed quickly. At this time, the two surfaces of the liquid film reach energy balance, mass balance and force balance to maintain the continuity of the liquid film.

[0054] Under the support of the membrane substrate 210, the condensable vapor liquid can form a continuous and uninterrupted liquid film. Non-condensable gases are blocked by the liquid film within the inlet end 111, which helps to avoid the problem of poor blocking effect on non-condensable impurity gases due to discontinuity on the liquid film.

[0055] Specifically, when impurity gas needs to pass through the liquid film, it first needs to dissolve into the interior of the liquid film and then diffuse into the other side. On the other side of the liquid film, due to the concentration difference between the partial pressure of impurities in the space and the concentration inside the liquid film, it diffuses into the gas phase in the space.

[0056] According to Higbie's theory of permeation mass transfer, in gas-liquid contact mass transfer devices, both phases operate in repetitive, brief contacts, preventing the establishment of equilibrium. The mass transferred into the liquid is due to unsteady molecular transfer, and because the contact time is too short, only a very short distance can be permeated. Furthermore, it is believed that the mass transfer resistance is mainly within the liquid film, and the bubble mass transfer process can be approximated using a one-dimensional unsteady diffusion equation and similar boundary conditions.

[0057]

[0058] Where C is the concentration of the impurity gas in the liquid film, D is the diffusion coefficient of the impurity gas in the liquid film, t is time, and y is the direction of mass transfer, the instantaneous mass transfer flux can be obtained as:

[0059]

[0060] It is evident that the instantaneous mass transfer flux is limited by the concentration c of the impurity gas in the liquid film and the diffusion coefficient D.

[0061] Understandably, see Figure 2 The membrane substrate 210 has multiple perforations 211 arranged in a close arrangement, meaning that the membrane substrate 210 is made of a material with good air permeability. Liquid that can condense vapor can fill the multiple perforations 211, thus forming a continuous and uninterrupted liquid film. The close arrangement of perforations 211 helps to enhance the heat transfer of the membrane substrate 210, allowing heat to be transferred from one end of the liquid film to the other end. This allows the heat released by vapor condensation to be converted into the heat absorbed by the evaporation of the liquid film, thereby achieving energy balance, material balance, and force balance on both sides of the liquid film to maintain the continuity of the liquid film.

[0062] Specifically, the membrane substrate 210 can be a metal mesh, fiber cloth or polymer mesh, etc. The surface of the membrane substrate 210 is provided with multiple perforations 211 arranged in close proximity to meet the requirements of heat diffusion, i.e., vapor penetration.

[0063] It should be noted that the perforation 211 is not limited to the perforation 211 that is visible to the human eye. The perforation 211 can also be a small hole, or even a micro hole that is not easily detected by the human eye, and can also meet the needs of heat transfer.

[0064] Understandably, when it is necessary to remove non-condensable air from water vapor, the liquid film can be a water film. When water vapor comes into contact with the liquid film, the liquid film can absorb the water vapor, while the solubility of non-condensable air is relatively low, so that the water vapor can pass through the liquid film to achieve purification.

[0065] Understandably, see Figure 2 In order to achieve the laying of the membrane substrate 210 onto the cavity 110, especially when the membrane substrate 210 is made of soft material, the vapor boundary membrane purification device also includes an annular support 220.

[0066] The outer peripheral surface of the support 220 is connected to the inner wall surface of the cavity 110. For example, the support 220 can be connected to the wall surface of the cavity 110 by screws or welding. The outer peripheral surface of the support 220 can fit tightly against the inner wall surface of the cavity 110, thereby preventing gas from escaping through the gap between the outer peripheral surface of the support 220 and the inner wall surface of the cavity 110. For example, see... Figure 2 The container 100 is a cylindrical body extending from left to right, the cavity 110 is cylindrical, and the support 220 is annular. The outer diameter of the support 220 is adapted to the inner diameter of the cavity 110, so that the outer peripheral surface of the support 220 can fit with the inner peripheral surface of the cavity 110.

[0067] The membrane substrate 210 is laid on the inner periphery of the support 220. When the membrane substrate 210 is made of soft material, the membrane substrate 210 can be stretched and laid flat on the inner periphery of the support 220, that is, the membrane substrate 210 can fill the cavity on the inner periphery of the support 220, so that the membrane substrate 210 can be connected to the inner wall of the cavity 110, and the membrane substrate 210 can divide the cavity 110 into the opposite inlet end 111 and outlet end 112.

[0068] Understandably, the membrane assembly 200 also includes a liquid compensator containing condensable vapor liquid. The liquid compensator is connected to the membrane substrate 210 so that the condensable vapor liquid can flow to the perforations 211 and form a liquid film. The liquid compensator can replenish the condensable vapor liquid onto the membrane substrate 210. After the membrane substrate 210 adsorbs the condensable vapor liquid, under the action of the interfacial forces between liquid and solid molecules, the liquid can adhere to the surface of the membrane substrate 210, thereby forming a condensable vapor liquid film. This liquid film effectively blocks non-condensable air, and the vapor can pass through the liquid film to enter the outlet end 112, achieving vapor purification.

[0069] Specifically, the liquid compensator may include a storage tank and a pump body. The storage tank is used to contain the liquid that can condense vapors, while the pump body is connected to the storage tank. The outlet of the pump body is located above the membrane substrate 210. When the pump body is in operation, it can guide the liquid that can condense vapors from top to bottom to the top of the membrane substrate 210. Under the action of gravity, the liquid that can condense vapors can adhere to the membrane substrate 210 to form a liquid film of condensable vapors.

[0070] It should be understood that in some other embodiments, the liquid compensator also includes a collector located below the membrane substrate 210, thereby collecting the liquid that can condense vapors dripping along the membrane substrate 210. Under the circulation action of the pump, the liquid that can condense vapors can be reused, which is beneficial to saving resources.

[0071] It is understood that, in this embodiment, in order to improve the control accuracy of the pressure at the inlet 111 and the pressure at the outlet 112, the vapor boundary membrane purification device further includes a first pump body, a controller, a first pressure sensor for detecting the pressure at the inlet 111, a second pump body, and a second pressure sensor for detecting the pressure at the outlet 112.

[0072] Specifically, the first pump body is connected to the mixed gas inlet 113, and both the first pump body and the first pressure sensor are connected to the controller signal, such as an electrical signal or a pulse signal. The second pump body is connected to the steam outlet 115, and both the second pump body and the second pressure sensor are connected to the controller signal, such as an electrical signal or a pulse signal.

[0073] Based on the values ​​of the first and second pressure sensors, the controller can determine whether the pressure at the inlet 111 and the pressure at the outlet 112 are both within the set threshold range. Through the compensation action of the first and second pump bodies, the pressure stability at the inlet 111 and the outlet 112 is maintained.

[0074] The controller can calculate the pressure difference between the inlet end 111 and the outlet end 112, and coordinate with the operation of the first pump body and the second pump body to control the pressure difference between the inlet end 111 and the outlet end 112 within a set range. This avoids the problem of liquid film gaps caused by a large pressure difference between the inlet end 111 and the outlet end 112. It is beneficial to block non-condensable gases at the inlet end 111, while steam can enter the outlet end 112 to achieve steam purification.

[0075] It is understood that embodiments of the invention also provide a purification method applied to the vapor purification apparatus described above, comprising the following steps:

[0076] S100, the membrane substrate 210 is connected to the inner wall surface of the cavity 110, and a liquid film is formed on the membrane substrate 210, so that the mixed gas is introduced into the inlet end 111 from the mixed gas inlet 113;

[0077] S200, with the radius of the perforation 211 as r, the surface tension coefficient of the liquid film as σ, the pressure at the inlet end 111 as P1, and the pressure at the outlet end 112 as P2; control the pressure difference between the inlet end 111 and the outlet end 112 so that P1-P2≤2σ / r, so that the liquid film can be continuously and uninterruptedly attached to the film substrate 210.

[0078] S300 collects steam from outlet 112 through steam outlet 115.

[0079] Before introducing the mixed gas, the vapor boundary membrane purification device needs to connect the membrane substrate 210 to the inner wall of the cavity 110 and form a liquid film of condensable vapor on the membrane substrate 210. Then, the vapor mixed with non-condensable impurity gas is introduced into the inlet end 111 from the mixed gas inlet 113.

[0080] According to the pressure balance formula for liquids, P = 2σ / r, where P is the pressure difference, σ is the surface tension coefficient of the liquid film, and r is the principal radius of curvature of the interfacial droplets. Taking saturated water vapor as an example, the film substrate 210 is a perforated metal mesh, fiber cloth, or polymer mesh cloth, etc., and the liquid film is a water film.

[0081] When liquid water is adsorbed on the surface of the membrane substrate 210, the liquid can fill the perforations 211 of the membrane substrate 210 under the action of the interfacial force between water molecules and solid molecules. The liquid water is adsorbed on the surface of the membrane substrate 210 and forms a water film. When the membrane substrate 210 is a fabric, the material of the membrane substrate 210 can adsorb and retain moisture.

[0082] With the radius of the perforation 211 as r, according to the pressure balance formula of liquid, when P≤2σ / r, the water film can be continuously and uninterruptedly adsorbed on the film substrate 210, and the water film can form a continuous phase. The film substrate 210 provides support for the water film, so that water vapor and non-condensable air can come into contact with the water film.

[0083] The cavity 110 is divided into an inlet end 111 and an outlet end 112 by a water film. The pressure at the inlet end 111 is P1, and the pressure at the outlet end 112 is P2, where P1 > P2. Specifically, the partial pressure of water vapor at the inlet end 111 is P3, and the partial pressure of other non-condensable gases is P4, so P1 = P3 + P4.

[0084] When steam comes into contact with a water film, mass transfer occurs between the steam and the water film. The steam can release heat and liquefy into water molecules that can condense in the water film. The heat released after the water vapor liquefies is Q1. The water molecules can absorb heat and vaporize to reform water vapor. The heat absorbed by the water molecules during vaporization is Q2. When the system is in equilibrium, Q1 = Q2.

[0085] The purified steam is continuously discharged from the steam outlet 115 to the outlet end 112, which makes P3>P2. The pressure loss of the water vapor is the difference between P3 and P2. The pressure difference between P3 and P2 can drive the water vapor through the water film. At this time, the number of water molecules condensed in the water film is the same as the number of water molecules vaporized from the water film, and the water film maintains an equilibrium state.

[0086] When non-condensable gases come into contact with a water film, their solubility in the water film is very low. For example, at 1 atmosphere and 20 degrees Celsius, the solubility of oxygen in a water film is only 6.8 ml / L. Due to the obstruction of the water film, non-condensable air must overcome its resistance to pass through. This resistance is influenced by the solubility of the non-condensable gas in the water film, the diffusion forces on both sides of the water film, and the binding force on the gas escaping from the water surface. Consequently, very little non-condensable gas can pass through the water film and enter the outlet 112. In other words, macroscopically, non-condensable air cannot pass through the water film, thus achieving the separation of steam and non-condensable air, and consequently, the purification of the steam. Under the purification effect of this membrane purification device, the purity of the steam is improved, allowing it to meet the requirements of various processes and increasing the controllability of the processes.

[0087] Example 2, see Figure 3This embodiment of the invention also provides a vapor boundary membrane purification device, the main difference from Embodiment 1 is that the arrangement of the boundary membrane assembly 200 is different.

[0088] Understandably, specifically, the cavity 110 contains a liquid that can condense vapor, the outlet end 112 is located above the liquid surface of the liquid that can condense vapor, and the inlet end 111 is located below the liquid surface of the liquid that can condense vapor, that is, the liquid that can condense vapor fills the inlet end 111.

[0089] Furthermore, the membrane substrate 210 is immersed in a liquid that can condense vapor, and the inlet end 111 also includes an impurity gas outlet 114. The impurity gas outlet 114 and the mixed gas inlet 113 are located below the membrane substrate 210 and at opposite ends of the cavity 110.

[0090] When the mixed gas is introduced into the inlet end 111 from the mixed gas inlet 113, the mixed gas comes into full contact with the liquid of condensable vapor. The vapor can condense in the liquid of condensable vapor and pass through the membrane substrate 210, thereby achieving heat absorption and re-evaporation at the liquid surface of the liquid of condensable vapor. The non-condensable impurity gas is discharged from the inlet end 111 from the impurity gas outlet 114, thereby achieving the separation of vapor and non-condensable impurity gas.

[0091] It is understood that the membrane substrate 210 may be tubular, and its two ends are connected to the left and right walls of the cavity 110, respectively. That is, the membrane substrate 210 is horizontally mounted inside the container 100, and the mixed gas inlet 113 and impurity gas outlet 114 are respectively positioned opposite to the two ports of the membrane substrate 210. (See also...) Figure 3 The mixed gas inlet 113 is connected to the left port of the membrane substrate 210, and the impurity gas outlet 114 is connected to the right port of the membrane substrate 210.

[0092] The mixed gas introduced through the mixed gas inlet 113 enters the tubular membrane substrate 210, so that the vapor can condense in the liquid that can condense vapor filled in the inlet end 111, while the non-condensable impurity gas is discharged from the other end of the membrane substrate 210 from the inlet end 111, thereby avoiding the problem of liquid film damage caused by excessive pressure difference between the inlet end 111 and the outlet end 112.

[0093] It is understandable that the membrane substrate 210 is gradually tilted upward from left to right. Since the solubility of impurity gas in liquids that can condense vapors is very low, the impurity gas can gradually move to the right along the tilt direction of the membrane substrate 210 and be discharged from the impurity gas outlet 114 to the inlet end 111. This can avoid the problem of excessive pressure difference between the inlet end 111 and the outlet end 112 due to the accumulation of impurity gas.

[0094] In some other embodiments, the membrane substrate 210 is planar and arranged laterally; or, the membrane substrate 210 is arc-shaped and arranged laterally. When the mixed gas is introduced into the inlet end 111 from the mixed gas inlet 113, the bubbles can move upward, the vapor condenses in the liquid that can condense vapor, while the impurity gas continues to move upward and, guided by the membrane substrate 210, is discharged from the inlet end 111 from the impurity gas outlet 114, thereby achieving the separation of vapor and impurity gas.

[0095] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

[0096] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for purifying steam, characterized in that, A membrane purification device for vapor, the membrane purification device for vapor comprising: A container with an internal cavity; A boundary membrane assembly is disposed within the cavity and connected to the container. The boundary membrane assembly can fill the cavity with a liquid that can condense vapors. The liquid level of the liquid that can condense vapors divides the cavity into an inlet end and an outlet end. The inlet end is connected to a mixed gas inlet, and the outlet end is connected to a vapor outlet. The boundary membrane assembly includes a membrane substrate, which is connected to the inner wall surface of the cavity; The boundary membrane assembly further includes a liquid compensator containing the liquid of the condensable vapor, and the liquid compensator is connected to the membrane substrate so that the liquid of the condensable vapor can flow to the membrane substrate and form a liquid film. The membrane substrate has perforations and is used to attach the liquid that can condense vapor to form a liquid film of condensable vapor. The method for purifying the vapor includes: The mixed gas is introduced into the inlet end from the mixed gas inlet; the liquid of the condensable vapor absorbs the vapor in the mixed gas, and by utilizing the phase change of the vapor, that is, the process of the vapor changing from the gaseous state to the liquid state and then from the liquid state to the gaseous state, the vapor can pass through the liquid of the condensable vapor; Let the radius of the perforation be r, the surface tension coefficient of the liquid film be σ, and the pressure at the inlet end be... The pressure at the outlet end is Control the pressure difference between the inlet and the outlet to ensure that - 2σ / r, the liquid film can be continuously and uninterruptedly attached to the film surface substrate; Steam is collected at the outlet end through the steam outlet.

2. The method for purifying steam according to claim 1, characterized in that, The inlet end and the outlet end are located on the left and right sides of the membrane substrate, respectively, and both the inlet end and the outlet end are opposite to the perforation.

3. The method for purifying steam according to claim 1, characterized in that, The inlet end is also connected to an outlet for impurity gas.

4. The method for purifying steam according to claim 3, characterized in that, The membrane substrate is tubular, with the mixed gas inlet and the impurity gas outlet respectively opposite to the two ends of the membrane substrate; or, the membrane substrate is planar; or, the membrane substrate is arc-shaped.

5. The method for purifying steam according to any one of claims 1-4, characterized in that, The film substrate has a plurality of perforations arranged in a close arrangement.

6. The method for purifying steam according to any one of claims 1-4, characterized in that, The vapor interfacial purification device further includes a support, to which both the membrane substrate and the inner wall of the cavity are connected to the support to fix the relative positional relationship between the membrane substrate and the cavity; and / or, The film substrate is a metal mesh, fiber cloth, or polymer mesh cloth; and / or... The liquid film is a water film.

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