System and method for integrity testing of a tubular membrane module

Abstract

This application provides an integrity testing system and method for tubular membrane modules. The testing system includes a liquid path, a gas path, and a detection path. The liquid path provides a wetting liquid to the tubular membrane module, which forms a liquid film on the wall of the filter tube within the module. The gas path provides a pressure-measuring gas to the detection path, which includes a pressure gauge. The tubular membrane module is connected to the detection path. The liquid path and gas path are connected together at one end of the tubular membrane module, and the pressure gauge is connected to the other end. The pore diameter of the filter tube is not less than 0.45 μm, the viscosity of the wetting liquid is not less than 1.5 mPa·s, and the pressure of the pressure-measuring gas relative to atmospheric pressure is not less than 0.01 MPa. The integrity testing method for the tubular membrane module provided in this application includes: wetting the wall of the filter tube with the wetting liquid, forming a liquid film on the wall of the filter tube; and introducing the pressure-measuring gas from one end of the filter tube to detect the gas pressure at the other end of the filter tube.

Description

Technical Field

[0001] This application relates to the field of membrane treatment technology, and in particular to an integrity testing system and method for tubular membrane modules. Background Technology

[0002] Membrane treatment technology has the advantages of low energy consumption, high separation efficiency, simple process and no need to add reagents, and therefore it is widely used in separation processes in various industries.

[0003] Membrane modules are formed by assembling membrane elements such as membrane fibers and membrane tubes together in a certain form. During actual application, membrane modules may experience breakage of membrane fibers or membrane tubes due to factors such as the nature of the incoming materials, the process flow, and the membrane materials themselves. This can affect the separation effect and product quality, disrupt the stable operation of the system, and also affect the service life of the membrane elements and the separation energy consumption.

[0004] The breakage or damage of membrane fibers or tubing in membrane modules has long been a problem plaguing the membrane separation industry. For example, in the drinking water treatment industry, the U.S. Environmental Protection Agency requires all water treatment plants using membrane technology to conduct daily membrane integrity tests to prevent contamination of the treated water due to membrane fiber or tubing breakage.

[0005] The integrity test of the membrane module aims to find the damaged membrane fibers, and then seal and discard the damaged membrane fibers or membrane tubes in the module, while the remaining membrane fibers and membrane tubes continue to work.

[0006] Traditional membranes (such as hollow cellulose membranes or tubular membranes) typically have pore sizes in the hundreds of nanometers range, which are relatively small. Integrity testing methods for traditional small-pore membranes include:

[0007] Method #1: Pass the liquid to be tested into the membrane module. The liquid is usually water or ethanol. By observing the difference between the flow rate at the outlet of each membrane element and the flow rate of a normal membrane element, it can be determined whether the membrane element in the membrane module has been damaged or broken.

[0008] Method #2 involves immersing the membrane module in the test liquid or applying foam or soapy water to the concentrate side, and then passing gas at a certain pressure through the feed side. If the membrane element in the membrane module is damaged, some gas will pass through the rupture in the membrane wall into the concentrate side of the membrane element. The size and uniformity of the bubbles on the concentrate side are observed to determine whether the membrane element is damaged.

[0009] On the one hand, the difference in liquid flow rate is not obvious in method #1, and on the other hand, method #2 requires destroying the overall structure of the tubular membrane module in order to observe the bubbles from the side and thus identify the damaged membrane element.

[0010] On the other hand, if the membrane pore size is increased by 25 to 100 times, for example to about 10 μm, the above detection methods become unreliable. Both liquids and gases will quickly pass through the sidewalls of the membrane tubes and filaments, and will not be limited to the damaged area. In other words, current integrity detection methods cannot handle membranes with larger pore diameters. Summary of the Invention

[0011] To address or improve at least one of the problems mentioned in the background art, this application provides an integrity testing system and method for tubular membrane modules.

[0012] The integrity testing system for tubular membrane modules provided in this application includes:

[0013] A liquid path, the liquid path being used to provide a wetting liquid to the tubular membrane module, the wetting liquid being used to coat the walls of the filter tubes in the tubular membrane module with a liquid film; and

[0014] The system includes a gas path and a detection path. The gas path provides pressure-measuring gas to the detection path, which includes a pressure gauge. The tubular membrane module is connected to the detection path. The liquid path and the gas path are connected together to one end of the tubular membrane module, and the pressure gauge is connected to the other end of the tubular membrane module.

[0015] The membrane pore diameter of the filter tube is not less than 0.45 μm, the viscosity of the wetting liquid is not less than 1.5 mPa·s, and the pressure of the pressure measuring gas relative to atmospheric pressure is not less than 0.01 MPa.

[0016] In at least one embodiment, the wetting liquid is an aqueous solution of glycerol.

[0017] In at least one embodiment, the wetting liquid is an aqueous solution of at least one of polyethylene glycol, starch, and polyacrylamide.

[0018] In at least one embodiment, the fluid path includes:

[0019] A liquid storage container for providing and collecting the wetting liquid; and

[0020] The system includes a first valve and a second valve in the liquid path, with the detection path connected between the first valve and the second valve.

[0021] With the first valve in the liquid path closed, the liquid path stops supplying the wetting liquid to the detection path.

[0022] With the second valve in the liquid path open, the wetting liquid in the tubular membrane module can flow back to the storage container through the pipes and the second valve in the liquid path.

[0023] The liquid path is used to supply the wetting liquid from the tubular membrane module, which is fitted over the outside of the filter tube, to the inside of the tubular shell, thereby wetting the filter tube inside the tubular shell.

[0024] In at least one embodiment, the gas path includes:

[0025] A compressed air source is used to provide the pressure measuring gas to the detection path;

[0026] A pressure reducing valve is used to adjust the pressure of the pressure measuring gas.

[0027] The gas path is used to connect to one end of the filter tube to input the pressure measuring gas into the filter tube.

[0028] In at least one embodiment, the tubular membrane assembly includes the filter tube and a shell sleeved over the outside of the filter tube, with a connecting portion provided at the end of the shell.

[0029] The detection path also includes:

[0030] The connector is cylindrical and can flexibly and sealingly cover the end of the filter tube;

[0031] A connector, the two ends of which are used to connect to the connector head and the pressure gauge; and

[0032] A connecting member is provided for connecting the connector and the connecting portion to prevent the pressure gauge from accidentally falling off.

[0033] In at least one embodiment, the tubular membrane module includes a filter tube and a housing sleeved over the outside of the filter tube.

[0034] The side wall of the tube shell is connected to a pipe and a first valve for the detection path. When the first valve for the detection path is open, some of the pressure measuring gas flowing out from the damaged position of the filter tube is discharged after passing through the first valve for the detection path.

[0035] The integrity detection method for tubular membrane modules provided in this application is used to detect the integrity of the filter tubes in the tubular membrane module. The detection method uses the tubular membrane module integrity detection system described above, and the detection method includes:

[0036] The wetting liquid is used to wet the wall of the filter tube, and the wetting liquid forms a liquid film on the wall of the filter tube; and

[0037] The pressure measuring gas is introduced into one end of the filter tube to detect the gas pressure at the other end of the filter tube.

[0038] In at least one embodiment, the viscosity of the wetting liquid, the pressure of the pressure measuring gas, and the membrane pore diameter of the filter tube are controlled such that when the gas pressure is detected from the other end of the filter tube, the ratio of the difference between the gas pressure detection values ​​of the filter tube that meets the integrity requirements and the filter tube that does not meet the integrity requirements to the gas pressure detection value of the filter tube that meets the integrity requirements is greater than 30%.

[0039] In at least one embodiment, the tubular membrane assembly includes a plurality of filter tubes, and the wetting liquid is injected into the tube shell from one end of the tubular membrane assembly that is sleeved on the outside of the filter tubes, and the pressure measuring gas is introduced into the filter tubes one by one, or the pressure measuring gas is introduced into more than one filter tube simultaneously.

[0040] For filter tubes with a pore diameter greater than 0.45 μm, the detection system provided in this application loads a liquid film onto the filter tube using an impregnating liquid, thereby detecting damaged filter tubes in the tubular membrane module by measuring the pressure difference between the two ends of the filter tube. The viscosity of the impregnating liquid is not less than 1.5 mPa·s, and the pressure of the measuring gas relative to atmospheric pressure is not less than 0.01 MPa, ensuring smooth liquid film formation. This allows for accurate and convenient identification of damaged filter tubes using pressure gauge readings, eliminating the need for disassembling the tubular membrane to individually check for filter tube damage.

[0041] The detection method provided in this application uses the aforementioned detection system and also possesses the aforementioned advantages. Attached Figure Description

[0042] Figure 1 A schematic diagram of the tubular membrane module and pressure gauge assembly of the integrity detection system for a tubular membrane module according to an embodiment of this application is shown.

[0043] Figure 2 A schematic diagram of the gas flow direction in the intact and damaged filter tubes of the tubular membrane module integrity detection system according to an embodiment of this application is shown.

[0044] Figure 3 A schematic diagram of the overall structure of an integrity detection system for a tubular membrane module according to an embodiment of this application is shown.

[0045] Explanation of reference numerals in the attached figures

[0046] 1. Tubular membrane module;

[0047] 2. Filter tubes; 21. Intact filter tubes; 22. Damaged filter tubes;

[0048] 3. Tube shell; 31. Connecting part;

[0049] 4. Liquid circuit; 41. Liquid storage tank; 42. Pump; 43. First valve of liquid circuit; 44. Second valve of liquid circuit;

[0050] 5. Air path; 51. Compressed air source; 52. Pressure reducing valve; 53. Air path shut-off valve;

[0051] 6. Detection path; 61. Pressure gauge assembly; 611. Pressure gauge; 612. Connector; 6121. Connecting arm; 613. Connecting piece; 614. Connecting rope; 62. Detection path valve assembly; 621. Detection path first valve; 622. Detection path second valve Detailed Implementation

[0052] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaustively describe all possible methods of this application, nor to limit the scope of this application.

[0053] Traditional small-pore filter tubes work by trapping pollutants in the water through micropores in the membrane wall of the filter unit, thus purifying the water. However, they inevitably suffer from severe clogging problems. This often requires frequent replacement of the filter unit, which significantly increases the operating and processing costs of the equipment and, to some extent, limits its application and development.

[0054] Currently, there is a type of large-pore tubular membrane module. The filter tubes of this module can be coated with a special agent in a semi-permanent manner to filter and adsorb pollutants in water. Through a special process design, the agent can be repeatedly eluted and coated, achieving a degree of "permanent" use for the filter tubes. This solves the fouling problem of conventional filtration membranes, reduces operating costs, and increases production capacity. However, traditional integrity testing methods and systems for small-pore filter tubes are not suitable for integrity testing of large-pore tubular membrane modules. Therefore, designing integrity testing methods and systems specifically for large-pore tubular membrane modules is of practical significance.

[0055] This application provides an integrity testing system and method for tubular membrane modules, used to test tubular membrane modules with filter tubes having the aforementioned large pore size. A large pore size filter tube can refer to a filter tube whose sidewall has a pore diameter of not less than 0.45 μm. In one embodiment of this application, the pore diameter of the filter tube is 0.45–25 μm.

[0056] For example, see Figure 1 , Figure 2 The object of testing can be a tubular membrane module 1, which may include filter tubes 2 and a housing 3 fitted over the filter tubes 2. The diameter of the opening of the housing 3 may be 2 inches (50 mm), 4 inches (100 mm), 5 inches (125 mm), 6 inches (150 mm), 8 inches (200 mm), 10 inches (250 mm), or larger, and the filter tubes 2 encapsulated inside the housing 3 may be one or more, such as one, seven, 100, or more. The material of the filter tubes 2 may be, for example, nylon.

[0057] The integrity testing method provided in this application includes testing each filter tube 2 individually. The testing method may include:

[0058] (S1) Wetting Coating. For example, a layer of wetting liquid with a certain viscosity is uniformly loaded onto the wall of filter tube 2. The pore size of filter tube 2, which is the subject of this application, is relatively large compared to the pore size of traditional membranes. During air or water testing, the membrane pores of filter tube 2 are essentially unobstructed channels, making it impossible to determine the leakage point by observing the liquid flow rate or bubble size. However, uniformly loading a layer of wetting liquid with a certain viscosity onto the wall of filter tube 2 is equivalent to loading an airtight "liquid film" onto the wall of filter tube 2. Due to the relatively large degree of fracture, the damaged area remains an unobstructed channel, resulting in a clear difference between the intact filter tube 21 and the damaged filter tube 22 during subsequent air permeation testing (described later).

[0059] (S2) Ventilation detection. For example, filter tube 2 can be divided into an intact filter tube 21 and a damaged filter tube 22. A schematic diagram showing the gas flow direction in the intact filter tube 21 and the damaged filter tube 22 under the same intake pressure is shown below. Figure 2 As shown. In an intact filter tube 21, the gas does not penetrate the tube wall and moves upwards along the intact filter tube 21. However, in a damaged filter tube 22, the gas flows out through the damaged tube wall, resulting in a lower pressure at the top of the damaged filter tube 22, or even making it unmeasurable. Therefore, under the same inlet pressure conditions, by comparing the gas pressure values ​​at the top of different filter tubes 2, it can be determined whether the filter tube 2 is damaged.

[0060] Furthermore, the ambient temperature throughout the testing process can be between 5°C and 25°C. It is understood that this application does not limit the temperature range.

[0061] Furthermore, the viscosity of the wetting liquid used in the "immersion coating" step is not less than 1.5 mPa·s. For example, it can be 1.5–460 mPa·s. The wetting liquid can be an aqueous solution of at least one of the following substances: glycerol, polyethylene glycol, starch, polyacrylamide, etc. The wetting liquid can be a water-miscible liquid to facilitate rinsing and removal after testing.

[0062] Furthermore, in the ventilation detection step, the pressure of the gas being measured relative to atmospheric pressure can be 0.01–0.4 MPa.

[0063] See Figure 3 The integrity detection system for tubular membrane modules provided in this application embodiment may include a liquid path 4, a gas path 5, and a detection path 6.

[0064] Liquid path 4 is used to provide wetting liquid to detection path 6. Liquid path 4 may include a liquid storage container (e.g., liquid storage tank 41, liquid storage vessel, liquid storage box, etc.), pump 42, first liquid path valve 43, second liquid path valve 44, and corresponding pipelines that form a circulation loop. Detection path 6 can be connected between the first liquid path valve 43 and the second liquid path valve 44.

[0065] With the first valve 43 of the liquid path closed, the liquid path 4 stops supplying liquid to the detection path 6. Taking the storage container as the storage tank 41 as an example, with the second valve 44 of the liquid path open, the tubular membrane module 1 is fully wetted, and the excess wetting liquid can enter the storage tank 41 through the pipe of the liquid path 4, realizing the reuse of the wetting liquid.

[0066] Gas path 5 is used to provide pressure-measuring gas to detection path 6. Gas path 5 may include a compressed air source 51, a pressure reducing valve 52, a gas path shut-off valve 53, and corresponding pipelines. The compressed gas provided by the compressed air source 51 is used as the pressure-measuring gas for detection path 6. The compressed air source 51 may include an air compressor, gas cylinder, etc. The pressure reducing valve 52 is used to adjust the pressure of the pressure-measuring gas input to detection path 6, and the gas path shut-off valve 53 is used to control the opening and closing of gas path 5. Of course, this application does not limit the specific type of valve. For example, a single valve that simultaneously performs pressure regulation and shut-off functions can be used to replace the pressure reducing valve 52 and the gas path shut-off valve 53.

[0067] It is understandable that liquid path 4 and gas path 5 can also be connected to detection path 6 through their respective pipes. The specific connection point of liquid path 4 to detection path 6 can be one end of the tubular membrane module 1, for example, one end of the tube shell 3. The specific connection point of gas path 5 to detection path 6 can be one end of the filter tube 2 in the tubular membrane module 1.

[0068] See Figure 1 , Figure 3 The detection path 6 may include the tubular membrane module 1 to be detected, the pressure gauge assembly 61, and the detection path valve assembly 62. The other end of the tubular membrane module 1 may be connected to the pressure gauge assembly 61.

[0069] The pressure gauge assembly 61 may include a pressure gauge 611, a connector 612, a connector 613, and a connecting component (e.g., a connecting rope 614, a connecting chain, etc.). A connecting part 31 may be provided at the end of the housing 3.

[0070] The connector 612 is used to connect the filter tube 2 in the housing 3. For example, the material of the connector 612 can be a material with a certain degree of flexibility, such as silicone or rubber, and the shape of the connector 612 can be cylindrical. One end of the connector 612 can be flexibly sealed and covered to the end of the filter tube 2.

[0071] The two ends of the connector 613 are connected to the connector 612 and the pressure gauge 611. The connector 612 may also include a connecting arm 6121 extending radially outward toward the tubular membrane module 1. Taking the connecting member as a connecting rope 614 as an example, the connecting rope 614 is connected to the connecting part 31 of the tube shell 3 through the connecting arm 6121, thereby reinforcing the position of the connector 613, connector 612, and pressure gauge 611, and preventing the connector 613, connector 612, and pressure gauge 611 from being pushed out by air pressure, which could lead to air leakage or even safety accidents such as injury.

[0072] The connecting rope 614 can be set as an elastic rope, or the length of the connecting rope 614 can be adjusted according to the filter tube 2 at different positions being detected, so that the pressure gauge assembly 61 can complete the detection of the filter tube 2 at each position in the tubular membrane assembly 1.

[0073] See Figure 1 The casing 3 may also have openings on its circumferential surface, through which pipes and valves can be connected. For example, the casing 3 may have a first side hole and a second side hole located at both ends. The detection path valve assembly 62 includes a first detection path valve 621 and a second detection path valve 622. The first side hole of the casing is connected to the first detection path valve 621 via a pipe, and the second side hole of the casing is connected to the second detection path valve 622 via a pipe.

[0074] The working principle of the tubular membrane module integrity detection system provided in this application is as follows.

[0075] First, close the second valve 44 of the liquid path, the second valve 622 of the detection path, and the gas path shut-off valve 53. Open the first valve 43 of the liquid path and the first valve 621 of the detection path. Turn on the pump 42 to transport the liquid in the storage tank 41 to the tubular membrane module 1 through the connected pipe. The liquid enters from the lower end of the tubular membrane module 1 and gradually fills the interior of the tubular membrane module 1. When there is liquid at the first valve 621 of the detection path and no air bubbles flow out, close the first valve 621 of the detection path. At this time, most of the gas outside the filter tube 2 inside the tubular membrane module 1 is discharged.

[0076] The liquid continues to fill the interior of the tubular membrane module 1 until one end (e.g.) Figure 3 Liquid flowing out of the upper outlet indicates that the tubular membrane module 1 is filled with liquid. At this time, the pump 42 and the first liquid circuit valve 43 are closed to allow the wetting liquid to fully wet the filter tube 2 inside the tubular membrane module 1. It is understood that this application does not limit whether the wetting liquid wets the filter tube 2 from the inside or the outside of the filter tube 2.

[0077] After the filter tube 2 is fully wetted, open the second valve 44 of the liquid circuit to release the liquid inside the tubular membrane module 1, and transport it back to the storage tank 41 through the pipeline to realize the reuse of the wetted liquid.

[0078] After the tubular membrane module 1 is fully impregnated, the damaged filter tubes are inspected.

[0079] The purpose of closing the second valve 44 of the liquid circuit and opening the second valve 622 and the first valve 621 of the detection circuit of the tubular membrane module 1 is to allow the gas that penetrates the filter tube 2 to be discharged in time during the test so as not to affect the test results.

[0080] Turn on the compressed air source 51 and adjust the pressure reducing valve 10 to the required pressure value. Then, open the air circuit shut-off valve 53, and the gas enters one end of the filter tube 2 in the tubular membrane module 1 through the connected pipe. The wetting liquid will form a thin film on the wall of the filter tube 2, preventing the gas entering the filter tube 2 from directly penetrating the filter tube wall. The gas will then reach the other end of the filter tube 2, where the pressure gauge 611 reflects the pressure value. Of course, multiple air circuits 5 and pressure gauges 611 can be prepared to test multiple filter tubes 2 simultaneously.

[0081] Furthermore, the two ends of the detected damaged filter tubes can be sealed to allow the intact filter tubes to function properly in the tubular membrane module.

[0082] The integrity testing method and system for tubular membrane modules provided in this application can be used to inspect each filter tube 2 in the tubular membrane module 1, thereby accurately determining the location of the damaged filter tube 2. Compared with traditional visual inspection methods, this application determines whether there is damage by using the specific value of the pressure gauge, without disassembling the tubular shell. It can accurately determine the location of the damaged filter tube 22 in the entire membrane element without damaging the tubular membrane structure, helping users to actively find the damaged filter tube 22 for repair. This avoids the traditional destructive method of disassembling the entire filter module for inspection, and also avoids the waste of the entire filter module being unusable due to the damage of a single filter tube.

[0083] Below, this application also provides some embodiments. The inlet pressure can refer to the pressure of the pressure-measuring gas introduced into the filter tube 2 relative to atmospheric pressure. The sample number can refer to the number of the filter tube 2 involved in the experiment. The pressure gauge reading can refer to the reading of the pressure gauge 611 installed on the filter tube 2 under test, i.e., the gas pressure detection value. The sample state can refer to the state of the filter tube 2; "intact" means that the filter tube meets the integrity requirements, and "damaged" means that the filter tube is damaged and does not meet the integrity requirements. The glycerol viscosity can refer to the viscosity of the glycerol aqueous solution used at the corresponding temperature (e.g., 20°C) when the wetting liquid is an aqueous glycerol solution. The nylon tube pore diameter can refer to the diameter of the membrane pores of the nylon tube used when the filter tube 2 is a nylon tube.

[0084] Example 1

[0085] At room temperature (20°C), a glycerol aqueous solution with a viscosity of 10.0 mPa·s was prepared and poured into a storage tank 41. A tubular membrane module 1 with seven filter tubes 2 (two of which were damaged) was selected and assembled into the pipeline. The nylon tubes used for filter tubes 2 have a membrane pore diameter of 10 μm.

[0086] Close the second valve 44 of the liquid path, the second valve 622 of the detection path, and the gas path shut-off valve 53. Open the first valve 43 of the liquid path and the first valve 621 of the detection path. Start the pump 42 to deliver the glycerol aqueous solution into the tubular membrane module 1. When liquid flows out of the first valve 621 of the detection path, close the first valve 621 of the detection path. Continue to deliver the glycerol aqueous solution until liquid flows out from the upper end of the tubular membrane. After fully wetting for 15 minutes, open the second valve 44 of the liquid path to allow the glycerol aqueous solution to flow back into the storage tank 41, completing the wetting and coating process.

[0087] Turn on the compressed air source 51, adjust the pressure reducing valve 10 to provide pressure testing gas with a relative pressure of 0.1 MPa, connect the pipeline to one end of one of the filter tubes 2, and connect the pressure gauge 611 to the other end of the corresponding filter tube 2. Open the second valve 622 of the detection path, the first valve 621 of the detection path, and the air path shut-off valve 53, allowing gas to enter the filter tube 2. Read and record the reading of the pressure gauge 611. Close the air path shut-off valve 53, connect the air path and pressure gauge 611 to both ends of another filter tube 2, open the air path shut-off valve 53, and record the reading of the pressure gauge 611 until all filter tubes 2 have completed the air passage test.

[0088] After the test was completed, the tubular membrane module 1 was disassembled, the actual damage of the filter tube 2 was checked and compared with the corresponding pressure gauge 611 reading. The test results are shown in Table 1 below.

[0089] Table 1. Test Records of Damaged Tubular Membranes

[0090]

[0091]

[0092] Based on the test results, the integrity testing method and system for tubular membrane modules provided in this application can detect whether large-pore filter tubes are damaged without disassembling the tubular membrane module.

[0093] Aqueous solutions of substances such as polyethylene glycol, starch, and polyacrylamide have similar properties to aqueous solutions of glycerol, and therefore can also be used as wetting liquids.

[0094] Example 2

[0095] Glycerol aqueous solutions with viscosities of 1.3 mPa·s, 10.0 mPa·s, and 60.0 mPa·s were prepared at room temperature (20°C). First, the 1.3 mPa·s glycerol aqueous solution was poured into the storage tank 41. A tubular membrane module 1 with four filter tubes 2 (two of which were damaged) was selected and assembled into the pipeline. The nylon tubes used for the filter tubes 2 had a membrane pore diameter of 10 μm.

[0096] Close the second valve 44 of the liquid path, the second valve 622 of the detection path, and the gas path shut-off valve 53. Open the first valve 43 of the liquid path and the first valve 621 of the detection path. Start the pump 42 to deliver the glycerol aqueous solution into the tubular membrane module 1. When liquid flows out of the first valve 621 of the detection path, close the first valve 621 of the detection path. Continue to deliver the glycerol aqueous solution until liquid flows out from the upper end of the tubular membrane. After fully wetting for 15 minutes, open the second valve 44 of the liquid path to allow the glycerol aqueous solution to flow back into the storage tank 41, completing the wetting and coating process.

[0097] Turn on the compressed air source 51, adjust the pressure reducing valve 10 to provide pressure testing gas with a relative pressure of 0.1 MPa, connect the pipeline to one end of one of the filter tubes 2, and connect the pressure gauge 611 to the other end of the corresponding filter tube 2. Open the second valve 622 of the detection path, the first valve 621 of the detection path, and the air path shut-off valve 53. Gas enters the filter tube 2. Read and record the reading of the pressure gauge 611. Close the air path shut-off valve 53, connect the air pipeline and the pressure gauge 611 to both ends of another filter tube 2, open the air path shut-off valve 53, and record the reading of the pressure gauge 611. Repeat this process until all filter tubes 2 have completed the air passage test.

[0098] Then, glycerol aqueous solutions with viscosities of 10.0 mPa·s and 60 mPa·s were poured into the storage tank 41 in sequence, and the above operation steps were repeated to complete the test of all filter tubes.

[0099] After the test was completed, the tubular membrane module 1 was disassembled, the actual damage of the filter tube 2 was checked and compared with the reading of the corresponding pressure gauge 611. The test results are shown in Table 2 below.

[0100] Table 2 Test records of damaged tubular membranes at different glycerol viscosities

[0101]

[0102] The test results show that when the glycerol viscosity is too low, it cannot form an effective and complete "film"; while when the viscosity is too high, the glycerol will seal the damaged area of ​​the filter tube. Therefore, neither too low nor too high glycerol viscosity can accurately detect the damage status of the filter tube.

[0103] Example 3

[0104] A glycerol aqueous solution with a viscosity of 10.0 mPa·s was prepared at room temperature (20°C) and poured into the storage tank 41. A tubular membrane module 1 with four filter tubes 2 (two of which were damaged) was selected and assembled into the pipeline. The nylon tubes used for the filter tubes had a membrane pore diameter of 10 μm.

[0105] Close the second valve 44 of the liquid path, the second valve 622 of the detection path, and the gas path shut-off valve 53. Open the first valve 43 of the liquid path and the first valve 621 of the detection path. Start the pump 42 to deliver the glycerol aqueous solution into the tubular membrane module 1. When liquid flows out of the first valve 621 of the detection path, close the first valve 621 of the detection path. Continue to deliver the glycerol aqueous solution until liquid flows out from the upper end of the tubular membrane. After fully wetting for 15 minutes, open the second valve 44 of the liquid path to allow the glycerol aqueous solution to flow back into the storage tank 41, completing the wetting and coating process.

[0106] Turn on the compressed air source 51, adjust the pressure reducing valve 10 to provide pressure testing gas with a relative pressure of 0.05 MPa, connect the pipeline to one end of one of the filter tubes 2, and connect the pressure gauge 611 to the other end of the corresponding filter tube 2. Open the second valve 622 of the detection path, the first valve 621 of the detection path, and the air path shut-off valve 53. Gas enters the filter tube 2. Read and record the reading of the pressure gauge 611. Close the air path shut-off valve 53, connect the air pipeline and the pressure gauge 611 to both ends of another filter tube 2, open the air path shut-off valve 53, and record the reading of the pressure gauge 611 until all filter tubes have completed the air passage test.

[0107] Then adjust the intake pressure to 0.1MPa and 0.2MPa in sequence, and repeat the above operation steps.

[0108] After the test was completed, the tubular membrane module 1 was disassembled to check the damage of the filter tube and compare it with the reading of the corresponding pressure gauge 611. The test results are shown in Table 3 below.

[0109] Table 3. Test records of damaged tubular membranes under different inlet pressures.

[0110]

[0111]

[0112] The test results show that when the intake pressure is too low, there is no significant difference in the outlet pressure, making it impossible to determine whether the filter tube is intact or damaged. When the intake pressure is too high, it will directly break through the "film" coated on the filter tube, and the gas will flow directly from the filter tube wall, making it impossible to determine the condition of the filter tube.

[0113] It is understood that the aforementioned intake pressure and gas pressure refer to pressure values ​​relative to atmospheric pressure.

[0114] Example 4

[0115] Glycerol aqueous solutions with viscosities of 2.0 mPa·s, 4.0 mPa·s, 10.0 mPa·s, 60.0 mPa·s, and 200.0 mPa·s were prepared at room temperature (20°C) and poured into storage tank 41. Filter tube 2 used nylon tubing with membrane pore diameters of 0.45 μm, 5.0 μm, 10.0 μm, and 25.0 μm. The nylon tubing with the aforementioned membrane pore diameters was tested sequentially.

[0116] Close the second valve 44 of the liquid path, the second valve 622 of the detection path, and the gas path shut-off valve 53. Open the first valve 43 of the liquid path and the first valve 621 of the detection path. Start the pump 42 to deliver the glycerol aqueous solution into the tubular membrane module 1. When liquid flows out of the first valve 621 of the detection path, close the first valve 621 of the detection path. Continue to deliver the glycerol aqueous solution until liquid flows out from the upper end of the tubular membrane. After fully wetting for 15 minutes, open the second valve 44 of the liquid path to allow the glycerol aqueous solution to flow back into the storage tank 41, completing the wetting and coating process.

[0117] Turn on the compressed air source 51, adjust the pressure reducing valve 10 to provide pressure testing gas with a relative pressure of 0.051 MPa, connect the pipeline to one end of one of the filter tubes 2, and connect the pressure gauge 611 to the other end of the corresponding filter tube 2. Open the second valve 622 of the detection path, the first valve 621 of the detection path, and the air path shut-off valve 53. Gas enters the filter tube 2. Read and record the reading of the pressure gauge 611. Close the air path shut-off valve 53, connect the air pipeline and the pressure gauge 611 to both ends of another filter tube 2, open the air path shut-off valve 53, and record the reading of the pressure gauge 611 until all filter tubes have completed the air passage test.

[0118] After the test was completed, the tubular membrane module 1 was disassembled to check the damage of the filter tube and compare it with the reading of the corresponding pressure gauge 611. The test results are shown in Table 4 below.

[0119] Table 4. Test records of nylon tubes with different pore sizes at different glycerol concentrations.

[0120]

[0121] The test results show that, while maintaining an inlet pressure of 0.051 MPa, the integrity and damage of the filter membrane can be detected when the filter membrane pore size is 0.45 μm and the glycerol viscosity is 4.0 mPa·s; the integrity and damage of the filter membrane can also be detected when the filter membrane pore size is 5.0 μm and the glycerol concentration is 10.0 mPa·s; the integrity and damage of the filter membrane can also be detected when the filter membrane pore size is 10.0 μm and the glycerol concentration is 60.0 mPa·s; and the integrity and damage of the filter membrane can also be detected when the filter membrane pore size is 25.0 μm and the glycerol concentration is 200.0 mPa·s.

[0122] This shows that the integrity testing of filter membranes with different pore sizes has a certain correlation with the viscosity of the immersion liquid and the inlet pressure. Under the same inlet pressure, the larger the pore size of the filter membrane, the higher the viscosity of the immersion liquid required, and vice versa.

[0123] By comprehensively comparing the above embodiments, this application finds that in the detection method, the viscosity of the wetting liquid, the pressure of the measuring gas, and the membrane pore diameter of the filter tube 2 can be controlled so that when the gas pressure is measured from the other end of the filter tube 2, there is a significant difference in the gas pressure detection value (pressure gauge reading) between the filter tube 2 that meets the integrity requirements and the filter tube 2 that does not meet the integrity requirements. This significant difference can be defined as the ratio of the difference in gas pressure detection value between the filter tube 2 that meets the integrity requirements and the filter tube 2 that does not meet the integrity requirements to the gas pressure detection value of the filter tube 2 that meets the integrity requirements being greater than 30%.

[0124] For example, in Example 1, taking samples #1 and #5 as examples, the pressure reading of sample #1 is 0.08, and the pressure reading of sample #5 is 0.04. (0.08-0.04) / 0.08 = 50% > 30%, showing a significant difference between the two readings. In Example 2, taking samples #a and #c as examples when the glycerol viscosity is 10.0 mPa·s, the pressure reading of sample #a is 0.82, and the pressure reading of sample #c is 0.39. (0.82-0.39) / 0.82 = 52.4% > 30%, showing a significant difference between the two readings. Under the conditions of the above two examples, the matching relationship between the viscosity of the wetting liquid, the pressure of the measuring gas, and the membrane pore diameter of filter tube 2 meets the requirements of this detection method.

[0125] For multiple filter tubes 2, the pressure gauge readings corresponding to each filter tube 2 can be compared to determine if there are significant differences, thus confirming whether the filter tube is damaged. For a single filter tube 2, the air pressure test value of the filter tube 2 that meets the integrity requirements can be obtained in advance, and then the filter tube 2 to be tested can be tested under the same conditions.

[0126] It is understood that the numerical range A to B in this application includes two endpoint values ​​A and B.

[0127] The above description is the preferred embodiment of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. An integrity testing system for a tubular membrane module, characterized in that, The detection system includes: Liquid path (4), the liquid path (4) being used to provide a wetting liquid to the tubular membrane module (1), the wetting liquid being used to load a liquid film onto the wall of the filter tube (2) in the tubular membrane module (1); and The system comprises a gas path (5) and a detection path (6). The gas path (5) provides pressure-measuring gas to the detection path (6). The detection path (6) includes a pressure gauge (611). The tubular membrane assembly (1) is connected to the detection path (6). The liquid path (4) and the gas path (5) are connected together to one end of the tubular membrane assembly (1). The pressure gauge (611) is connected to the other end of the tubular membrane assembly (1). The membrane pore diameter of the filter tube (2) is not less than 0.45 μm, the viscosity of the wetting liquid is not less than 1.5 mPa.s, and the pressure of the pressure measuring gas relative to atmospheric pressure is 0.01~0.4 MPa.

2. The integrity detection system for tubular membrane modules according to claim 1, characterized in that, The wetting liquid is an aqueous solution of glycerol.

3. The integrity detection system for tubular membrane modules according to claim 1, characterized in that, The wetting liquid is an aqueous solution of at least one of polyethylene glycol, starch, and polyacrylamide.

4. The integrity testing system for tubular membrane modules according to claim 1, characterized in that, The liquid path (4) includes: A liquid storage container for providing and collecting the wetting liquid; and The first valve (43) and the second valve (44) of the liquid circuit are connected by the detection circuit (6). With the first valve (43) of the liquid path closed, the liquid path (4) stops supplying the wetting liquid to the detection path (6). With the second valve (44) of the liquid circuit open, the wetting liquid in the tubular membrane module (1) can flow back to the storage container through the pipe of the liquid circuit (4) and the second valve (44). The liquid path (4) is used to supply the wetting liquid from the tubular membrane assembly (1) through the shell (3) which is fitted on the outside of the filter tube (2) to the inside of the shell (3), thereby wetting the filter tube (2) inside the shell (3).

5. The integrity testing system for tubular membrane modules according to claim 1, characterized in that, The gas path (5) includes: Compressed air source (51) is used to provide the pressure measuring gas to the detection path (6); Pressure reducing valve (52) is used to adjust the pressure of the pressure measuring gas. The gas path (5) is used to connect to one end of the filter tube (2) to input the pressure measuring gas into the filter tube (2).

6. The integrity detection system for tubular membrane modules according to claim 1, characterized in that, The tubular membrane module (1) includes the filter tube (2) and a shell (3) sleeved on the outside of the filter tube (2), and a connecting part (31) is provided at the end of the shell (3). The detection path (6) also includes: Connector (612), the connector (612) is cylindrical, and the connector (612) can flexibly and sealingly cover the end of the filter tube (2); A connector (613), the two ends of which are used to connect to the connector (612) and the pressure gauge (611); and A connecting member for connecting the connector (613) and the connecting part (31) to prevent the pressure gauge (611) from accidentally falling off.

7. The integrity detection system for tubular membrane modules according to claim 1, characterized in that, The tubular membrane module (1) includes a filter tube (2) and a shell (3) sleeved on the outside of the filter tube (2). The side wall of the casing (3) is connected to a pipe and a first valve (621) of the detection path. When the first valve (621) of the detection path is open, part of the pressure measuring gas flowing out from the damaged position of the filter tube (2) is discharged after passing through the first valve (621) of the detection path.

8. A method for detecting the integrity of a tubular membrane module, used to detect the integrity of the filter tube (2) in the tubular membrane module (1), characterized in that, The detection method uses the integrity testing system for tubular membrane modules according to any one of claims 1 to 7, and the detection method includes: The wetting liquid is used to wet the wall of the filter tube (2), and the wetting liquid forms a liquid film on the wall of the filter tube (2); and The pressure measuring gas is introduced into one end of the filter tube (2) to detect the gas pressure at the other end of the filter tube (2).

9. The method for detecting the integrity of a tubular membrane module according to claim 8, characterized in that, The viscosity of the wetting liquid, the pressure of the pressure measuring gas, and the pore diameter of the filter tube (2) are controlled such that when the gas pressure is detected from the other end of the filter tube (2), the difference between the gas pressure detection values ​​of the filter tube (2) that meets the integrity requirements and the filter tube (2) that does not meet the integrity requirements is greater than 30%.

10. The method for detecting the integrity of a tubular membrane module according to claim 8, characterized in that, The tubular membrane module (1) includes a plurality of filter tubes (2). The wetting liquid is injected into the tube shell (3) of the tubular membrane module (1) which is sleeved on the outside of the filter tubes (2). The pressure measuring gas is introduced into the filter tubes (2) one by one, or the pressure measuring gas is introduced into more than one filter tube (2) at the same time.

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