Film coating effect testing and calculating method and system

Abstract

The invention relates to the technical field of membrane materials, and discloses a membrane coating effect testing and calculating method and system.The method comprises the steps that a small-scale test membrane assembly is tested, specifically, membrane filaments of the small-scale test membrane assembly are tested before and after being coated, and membrane filament physical performance parameters including the permeability coefficient and the membrane filament inner wall friction coefficient are calculated; counting the leaked-point membrane filaments coated on the industrial membrane module: sampling and counting the proportion of the membrane filaments completely coated on the selection layer in the industrial membrane module in the total membrane filament number, and recording the proportion as the proportion of non-leaked-point membrane filaments; calculating the coverage degree of a selection layer of the industrial membrane module: measuring fluid parameters of each port of the industrial membrane module, and combining a material conservation equation, a friction pressure loss relation equation and a permeation resistance loss relation equation by combining the physical performance parameters of the membrane filaments and the proportion of the non-leakage-point membrane filaments, so as to obtain the coverage degree of the selection layer of the industrial membrane module; and calculating the average selection layer coverage of the membrane filaments with the coating leakage points in the industrial membrane module. The method is particularly suitable for evaluating the selective layer coverage of the hollow fiber membrane adopting an inner coating process.

Description

Technical Field

[0001] This invention relates to the field of membrane materials technology, and in particular to a method and system for testing and calculating membrane coating effects. Background Technology

[0002] Membrane separation technology is a commonly used industrial technique for separating and concentrating mixed gases or solutions. The effective separation component is the selective layer on the membrane, which utilizes the different permeabilities of the components in the feed as they pass through the membrane to achieve separation. Hollow fiber membranes are widely used in industry due to their extremely high packing density (high membrane area per unit volume). The coating process of applying a casting solution to the hollow fiber membrane substrate to construct the selective layer is a key step in the manufacturing of this type of membrane module. If the selective layer is coated on the outside of the hollow fiber membrane fibers, the relatively long fibers will be in a state of oscillation under gas flow during actual operation, causing the selective layer coated on the outer surface of the fibers to break and detach due to friction and collision between the fibers. Coating the selective layer inside the hollow fiber membrane fibers avoids mechanical friction damage during operation. However, during the internal coating process of the membrane module, due to factors such as air bubbles entrained in the casting solution, local bending of the membrane fibers, and poor process operation, the selective layer may not be completely coated on the surface of the membrane substrate, forming leaks. The corresponding membrane fibers become coating leaky membrane fibers. When the mixed gas passes through these membrane fibers, a "short circuit" forms, preventing effective separation and resulting in a decrease in the overall selectivity of the membrane module, causing the product concentration to fail to meet separation requirements. Therefore, it is essential to examine and evaluate the coating effect of the selective layer on the membrane module after internal coating.

[0003] Industrial hollow fiber membrane modules consist of thousands of membrane filaments connected in parallel. After coating, the selective layer coverage of each filament cannot be directly observed, making it difficult to determine the quality of the selective layer coating. Among various indirect indicators, the pressure and flow rate at each channel inlet of industrial membrane modules are the easiest to obtain measurement parameters. Generally, under the same operating conditions, a larger pressure difference between the feed gas inlet and the permeate outlet, and a smaller permeate flow rate, indicate higher selective layer coverage and better coating effect. However, the relative magnitude of the pressure difference alone cannot determine the quality of the selective layer coating; in fact, there may be cases where the membrane module with the largest pressure difference in the same batch fails to meet the coating requirements. Currently, there is no literature explaining the quantitative relationship between the pressure and flow rate at each channel inlet of the membrane module and the selective layer coverage. Given that selective layer coverage is a crucial indicator for subsequent screening, recoating, sealing, repair, or disposal, determining and evaluating the selective layer coverage of industrial membrane modules based on specific testing methods has significant industrial application value.

[0004] Conventional testing methods for small-scale membrane modules (such as patents CN104353364B, CN114130205B, and CN115753332A) only install pressure gauges upstream of the module, lacking pressure detection points downstream, making it impossible to obtain the pressure difference before and after the fluid passes through the membrane fiber tube. Furthermore, even if a pressure gauge is added downstream of the membrane fiber, if its range is the same as other pressure gauges in the small-scale module testing system, even a high-precision gauge with an accuracy class of 0.1 (precision grade) will result in a measurement error exceeding 100%. Therefore, conventional testing methods cannot accurately calculate the friction coefficient of the membrane fiber inner wall. f Without this parameter, it is impossible to extend the estimation of the reference pressure drop of industrial membrane modules under different air intake conditions from the test results of small-scale membrane modules; conversely, it is also impossible to infer the coating condition of the selective layer from the pressure drop of industrial membrane modules.

[0005] In the testing of larger-scale industrial membrane modules, since these modules are composed of thousands of membrane fibers, conventional testing methods (such as patents CN106731862B and CN103764263B) require non-contact measuring instruments such as infrared, laser, X-ray, and ultrasound. These methods are costly and complex to operate, and typically can only detect large-scale damage or defects in the membrane fibers, not necessarily the lack of a thin (micrometer-level) selective layer coated on the membrane substrate. Therefore, both small-scale and industrial membrane module testing methods have limitations, and these two independent methods are insufficient for evaluating the selective layer coating effect of industrial membrane modules. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a method and system for testing and calculating membrane coating effects. This method combines small-scale membrane module testing with industrial membrane module testing and employs a dual-parameter index to evaluate the selective layer coverage of industrial membrane modules. This provides a reference for evaluating the performance of industrial membrane modules and is particularly suitable for evaluating the selective layer coverage of hollow fiber membranes using an internal coating process.

[0007] The technical solution adopted in this invention is as follows: A method for testing and calculating film coating effect, comprising: Small-scale membrane module testing: Tests were conducted on the membrane fibers of the small-scale membrane module before and after coating, and the physical performance parameters of the membrane fibers, including the permeation coefficient and the friction coefficient of the inner wall of the membrane fibers, were calculated. Statistics on Leaking Membrane Fibers in Industrial Membrane Modules: The percentage of membrane fibers with fully coated layers in industrial membrane modules is selected and statistically analyzed, and is recorded as the percentage of non-leaking membrane fibers. Selective layer coverage calculation for industrial membrane modules: Measure the fluid parameters at each port of the industrial membrane module, including the pressure and flow rate at the feed gas inlet, residual gas outlet, and permeate outlet; and combine the physical performance parameters of the membrane fibers with the proportion of non-leaking membrane fibers, simultaneously establish the material conservation equation, the frictional pressure loss equation, and the permeation resistance loss equation to calculate the average selective layer coverage of membrane fibers with coating leaks within the industrial membrane module.

[0008] Furthermore, in the small-scale membrane assembly testing, tests are performed on the membrane fibers of the small-scale membrane assembly before and after coating, including: The gas in the feed gas cylinder is controlled by sequentially passing through the feed gas valve to adjust the flow rate, the feed gas flow meter to measure the flow rate q1, and the feed gas pressure gauge to measure the pressure p1, before entering the small-scale membrane module measuring device from the feed gas inlet. The small-scale membrane module measuring device is equipped with at least one membrane fiber. The portion of the feed gas that passes through the membrane fiber selective layer to reach the outside of the membrane fiber is permeate gas, and the portion of the feed gas that flows out from the permeate gas outlet through the inner pipeline of the membrane fiber is permeate gas. The permeate gas flow rate q2 is measured by the permeate gas flow meter, and the pressure difference Δp between the feed gas inlet and the permeate gas outlet is measured by the differential pressure gauge, thereby calculating the permeate gas outlet pressure p2. An inert purge gas is used to carry the permeate gas through the membrane fibers out of the small-scale membrane module measuring device. During this process, the inert purge gas from the purge gas cylinder has its flow rate regulated by the purge gas valve and its flow rate q measured by the purge gas flow meter. 吹扫 It then enters the purge gas inlet of the small test membrane module measuring device, carries out the residual gas, and flows out from the residual gas outlet; After the permeate gas passes through a permeate pressure gauge (pressure p3) and a permeate flow meter (flow rate q3), it enters a gas detector to measure the proportion y of non-purge gas components in the permeate gas. 渗 .

[0009] Furthermore, in the small-scale membrane assembly test, the physical performance parameters of the membrane fibers are calculated, including: The permeability coefficient α before and after coating was calculated using the permeation resistance loss relationship equation. φ0% and α φ100% :

[0010]

[0011] The superscript "*" indicates measurement results obtained directly from hollow fiber membrane substrates without a selection layer. l The length of the membrane fibers in the small-scale membrane module. d The diameter of the membrane fibers in the small-scale membrane module; The coefficient of friction of the inner wall of the fully coated membrane fiber was calculated using the modified Darcy-Weisbach formula. f φ100% :

[0012] in, ρ g This represents the density of the gas inside the membrane filament.

[0013] Furthermore, when counting the leakage points of the membrane fibers coated in the industrial membrane module, the method for determining the membrane fibers with a fully coated layer in the industrial membrane module includes: applying a layer of surfactant to the cross-section of the hollow fiber membrane bundle at the upper end cap of the industrial membrane module, and then pumping air on the permeate side of the membrane module at a preset vacuum degree and flow rate, and observing the changes in the surfactant bubble film; wherein, the bubble film remains stationary is the membrane fiber with a fully coated layer, and the bubble film is drawn into the membrane fiber tube and sinks, which is the membrane fiber with an incompletely coated layer and leakage points.

[0014] Furthermore, when statistically analyzing the leakage points of the membrane fibers coated in the industrial membrane module, the proportion of membrane fibers with fully coated layers in the industrial membrane module is sampled and statistically analyzed. This includes: based on the symmetry and uniformity of the coverage of the selected layer, the sampling area is divided into multiple fan-shaped areas of equal shape and area at the same dividing angle; during the statistical analysis, a portion of the area is randomly selected for statistical analysis, and the number and total number of membrane fibers in the selected area that are drawn into the membrane fiber tube are calculated, thereby determining the proportion η of membrane fibers with fully coated layers in the total number of membrane fibers.

[0015] Furthermore, in the small-scale membrane assembly test, the length of the membrane fiber to be tested is 0.08~0.25m, and the differential pressure meter range is selected according to the different lengths of the membrane fiber to be tested. For each 0.1m membrane fiber length, the differential pressure meter is selected with a maximum range of 100~200Pa.

[0016] Furthermore, in the process of coating the leak point membrane fibers of the industrial membrane module, after applying a layer of surfactant to the cross-section of the hollow fiber membrane bundle at the upper end cap of the industrial membrane module, the pressure difference between the ambient pressure P0 and the pressure P3 at the permeate outlet during the evacuation operation is in the range of 5~15 kPa.

[0017] Furthermore, in the calculation of the selective layer coverage of the industrial membrane module, the pressure difference between the inlet pressure P1 and the ambient pressure P0 used when measuring the fluid parameters at each port of the industrial membrane module is in the range of 20~100 kPa.

[0018] A membrane coating effect testing system includes a small-scale membrane module testing subsystem, which includes a small-scale membrane module measuring device, a feed gas input component, a purge gas input component, a permeate gas measuring component, a differential pressure gauge, and a permeate gas flow meter. The small-scale membrane assembly measuring device is equipped with at least one membrane fiber. The portion of the feed gas that passes through the membrane fiber selective layer and reaches the outside of the membrane fiber is permeate gas, and the portion of the feed gas that flows out from the permeate gas outlet through the inner tube of the membrane fiber is permeate gas. The feed gas inlet of the small test membrane assembly measuring device is connected to the feed gas input assembly and the first end of the differential pressure gauge, the purge gas inlet is connected to the purge gas input assembly, the permeate gas outlet is connected to the permeate gas measuring assembly, and the residual gas outlet is connected to the second end of the differential pressure gauge and the residual gas flow meter.

[0019] Furthermore, the feed gas input assembly includes a feed gas cylinder, a feed gas valve, a feed gas flow meter, and a feed gas pressure gauge connected in sequence, with the feed gas pressure gauge connected to the feed gas inlet; the purge gas input assembly includes a purge gas cylinder, a purge gas valve, and a purge gas flow meter connected in sequence, with the purge gas flow meter connected to the purge gas inlet; the permeate gas measurement assembly includes a permeate gas pressure gauge, a permeate gas flow meter, and a gas detector connected in sequence, with the permeate gas pressure gauge connected to the permeate gas outlet.

[0020] A membrane coating effect testing system includes an industrial membrane module selective layer coverage testing subsystem, wherein the industrial membrane module selective layer coverage testing subsystem includes an industrial membrane module, a feed gas control component, a permeate gas control component, and a residual gas measurement component. The feed gas inlet of the industrial membrane module is connected to the feed gas control component, the permeate outlet is connected to the permeate control component, and the residual gas outlet is connected to the residual gas measurement component. The feed gas control assembly includes a blower, a first flow meter, a first valve, and a first pressure gauge connected in sequence, with the first pressure gauge connected to the feed gas inlet of the industrial membrane module; The permeate control assembly includes a vacuum gauge, a third flow meter, and a vacuum pump connected in sequence, with the vacuum gauge connected to the permeate outlet of the industrial membrane module; The residual gas measurement assembly includes a second pressure gauge and a second flow meter connected to the residual gas outlet.

[0021] The beneficial effects of this invention are as follows: (1) This invention can easily and accurately test and evaluate the selective layer coverage of industrial membrane modules, overcoming the current problems of difficulty in directly detecting the selective layer coating of industrial membrane modules and lack of evaluation methods for coating effect, and providing an easy-to-use quantitative evaluation index for evaluating the coating process effect in industry.

[0022] (2) The industrial membrane module selective layer coverage calculation designed in this invention avoids the need for expensive non-contact testing instruments, the test operation is simple, the versatility is strong, and the cost of testing and evaluation is low.

[0023] (3) The present invention improves the existing small-scale membrane module testing system, enhances the measurement accuracy of key performance parameters of membrane fibers, and provides an application extension for predicting the pressure drop of industrial membrane module equipment based on the test results of small-scale membrane modules. Attached Figure Description

[0024] Figure 1 This is a flowchart of a film coating effect testing and calculation method according to Embodiment 1 of the present invention.

[0025] Figure 2 This is a schematic diagram of the small-scale membrane assembly testing subsystem of Embodiment 1 of the present invention.

[0026] Figure 3 This is a schematic diagram of the industrial membrane module and the coated leak point in Embodiment 1 of the present invention.

[0027] Figure 4 This is a schematic diagram of the sampling and statistical region division in Embodiment 1 of the present invention.

[0028] Figure 5 This is a schematic diagram of the industrial membrane module selective layer coverage testing subsystem according to Embodiment 1 of the present invention.

[0029] Figure 6 This is a schematic diagram of the method for calculating the coverage of the coating leak point membrane fiber selective layer in Embodiment 1 of the present invention. Detailed Implementation

[0030] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] Example 1 This embodiment provides a method for testing and calculating the coating effect of membranes. First, the permeability coefficient and the friction coefficient of the inner wall of the membrane fibers in a small-scale membrane module before and after coating are measured and calculated. Then, the proportion of membrane fibers with fully coated selective layers (non-leaking membrane fibers) in the total number of membrane fibers in an industrial membrane module is sampled and statistically analyzed. The pressure and flow rate of the feed gas inlet, residual gas outlet, and permeate gas outlet of the industrial membrane module are measured. Finally, the material conservation equation, the friction pressure loss relationship equation, and the permeation resistance loss relationship equation are combined to calculate the key index parameters for evaluating the selective layer coating effect of the industrial membrane module.

[0032] like Figure 1 As shown, the method for testing and calculating the film coating effect includes the following steps: Small-scale membrane module testing: Tests were conducted on the membrane fibers of the small-scale membrane module before and after coating, and the physical performance parameters of the membrane fibers, including the permeation coefficient and the friction coefficient of the inner wall of the membrane fibers, were calculated. Statistics on Leaking Membrane Fibers in Industrial Membrane Modules: The percentage of membrane fibers with fully coated layers in industrial membrane modules is selected and statistically analyzed, and is recorded as the percentage of non-leaking membrane fibers. Selective layer coverage calculation for industrial membrane modules: Measure the fluid parameters at each port of the industrial membrane module, including the pressure and flow rate at the feed gas inlet, residual gas outlet, and permeate outlet; and combine the physical performance parameters of the membrane fibers with the proportion of non-leaking membrane fibers to calculate the average selective layer coverage of membrane fibers with coating leaks within the industrial membrane module by simultaneously establishing the material conservation equation, the friction pressure loss equation, and the permeation resistance loss equation.

[0033] It should be noted that this embodiment provides a dual-parameter evaluation scheme for the selective coating effect of industrial membrane modules: Addressing the difficulty in directly detecting the selective coating status of industrial membrane modules and the lack of evaluation methods for coating effect, this embodiment proposes a dual-parameter evaluation method for the selective coating effect of industrial membrane modules. Without employing complex and expensive non-contact measuring instruments, a simple scheme combining small-scale membrane module testing and industrial membrane module testing is used to obtain two key indicators: the proportion of non-leaking membrane fibers and the average selective layer coverage of leaking membrane fibers. These indicators are then used to evaluate the selective coating effect of the membrane module.

[0034] Furthermore, this embodiment can improve the scalability of performance parameters of pilot-scale membrane modules to industrial membrane modules: Addressing the problems in existing pilot-scale membrane module testing systems, such as the lack of necessary test point settings, large measurement errors in conventional testing methods leading to the inability to measure the performance parameters of membrane fibers in pilot-scale membrane modules, and the inability to effectively extend these parameters to industrial membrane modules, this embodiment improves the measurement accuracy of key performance parameters of membrane fibers in pilot-scale membrane modules by setting up differential pressure gauges of matching specifications at key locations in the pilot-scale membrane module testing system. It also enhances the scalability of these parameters for estimating pressure drop in industrial membrane modules.

[0035] Specifically, the method for testing and calculating the film coating effect in this embodiment is described in detail below.

[0036] I. Small-scale membrane assembly testing Industrial membrane modules contain long and numerous filaments, making it difficult to ensure complete coating of each filament. In contrast, small-scale membrane modules have shorter filaments, making complete coating easier and facilitating the measurement of the physical properties of individual filaments. The permeation coefficient and friction coefficient obtained from small-scale membrane modules can serve as reference values ​​for estimating the permeation performance and friction loss of long filaments in industrial membrane modules.

[0037] Preferably, this embodiment provides a small-scale membrane module testing subsystem, including a small-scale membrane module measuring device, a feed gas input component, a purge gas input component, a permeate gas measuring component, a differential pressure gauge, and a residual gas flow meter; wherein, the small-scale membrane module measuring device is equipped with at least one membrane fiber, the portion of the feed gas that passes through the membrane fiber selective layer to reach the outside of the membrane fiber is permeate gas, and the portion of the feed gas that flows out from the residual gas outlet through the inner pipeline of the membrane fiber is residual gas; the feed gas inlet of the small-scale membrane module measuring device is connected to the feed gas input component and the first end of the differential pressure gauge, the purge gas inlet is connected to the purge gas input component, the permeate gas outlet is connected to the permeate gas measuring component, and the residual gas outlet is connected to the second end of the differential pressure gauge and the residual gas flow meter.

[0038] like Figure 2 As shown, the feed gas input assembly includes a feed gas cylinder, a feed gas valve, a feed gas flow meter, and a feed gas pressure gauge connected in sequence, with the feed gas pressure gauge connected to the feed gas inlet; the purge gas input assembly includes a purge gas cylinder, a purge gas valve, and a purge gas flow meter connected in sequence, with the purge gas flow meter connected to the purge gas inlet; the permeate gas measurement assembly includes a permeate gas pressure gauge, a permeate gas flow meter, and a gas detector connected in sequence, with the permeate gas pressure gauge connected to the permeate gas outlet.

[0039] In the small-scale membrane module testing subsystem, the gas in the feed gas cylinder is sequentially regulated by the feed gas valve, its flow rate q1 is measured by the feed gas flow meter, and its pressure p1 is measured by the feed gas pressure gauge before entering the small-scale membrane module measuring device through the feed gas inlet. The small-scale membrane module measuring device is equipped with at least one membrane fiber. The portion of the feed gas that passes through the membrane fiber selective layer to the outside of the membrane fiber is permeate gas, and the portion of the feed gas that flows out through the permeate gas outlet through the inner pipeline of the membrane fiber is permeate gas. The permeate gas flow rate q2 is measured by the permeate gas flow meter, and the pressure difference Δp between the feed gas inlet and the permeate gas outlet is measured by the differential pressure gauge. The permeate gas outlet pressure p2 can be calculated.

[0040] Because the membrane fibers have low permeability and low permeate gas flow rate after coating, this embodiment uses inert purge gas to carry the permeate gas through the membrane fibers out of the small test membrane module measuring device. During this process, the inert purge gas from the purge gas cylinder has its flow rate regulated by the purge gas valve and the flow rate q is measured by the purge gas flow meter. 吹扫 The permeate then enters the purge gas inlet of the small-scale membrane module measuring device, carrying away residual gas before flowing out from the residual gas outlet. After the permeate pressure gauge measures the pressure p3 and the permeate flow meter measures the flow rate q3, the permeate enters the gas detector to measure the proportion y of non-purge gas components in the permeate. 渗 .

[0041] It is important to note that the membrane fibers in small-scale pilot membrane modules are relatively short (typically about 0.1 m), resulting in minimal pressure loss of the airflow after passing through the inner tubing of the membrane fibers (typically <200 Pa). However, the feed pressure is typically between 120 and 200 kPa. Even with a high-precision pressure gauge (range 0-200 kPa, accuracy class 0.1) installed at the membrane fiber outlet, the maximum permissible measurement error is still 200 Pa, with a relative error exceeding 100%. This error directly affects the coefficient of friction of the inner wall of the membrane fibers. f The accuracy of the calculation.

[0042] Therefore, this embodiment proposes to install differential pressure gauges at the inlet and outlet of the membrane fiber (feed gas inlet and residual gas outlet). For membrane fibers of different lengths (generally 0.08~0.25m), the differential pressure gauge corresponding to each 0.1m membrane fiber length is selected with a maximum range of 100~200 Pa. This ensures that even if the differential pressure gauge adopts industrial-grade precision (which is cheaper), its maximum measurement error will not exceed 5%.

[0043] Preferably, the permeability coefficient α before and after coating φ0% and α φ100% Calculated using the following equation relating seepage resistance loss:

[0044]

[0045] Wherein, "*" represents the measurement results obtained by directly using hollow fiber membrane substrates without a selection layer; l The length of the membrane fibers in the small-scale membrane module. d α represents the diameter of the membrane filament. It should be noted that in this embodiment, when testing the gas penetration through the membrane before and after coating, air is generally used as the medium; therefore, α φ0% and α φ100% The total permeability of the membrane is the air permeability.

[0046] In actual coating processes, the selective layer coverage of the membrane fibers is usually high (typically exceeding 95%). Assuming that the friction coefficient of the inner wall of the membrane fibers with different selective layer coverages is not significantly different after coating, the friction coefficient under fully coated membrane fibers is used in industrial membrane module calculations. f φ100% .

[0047] Preferably, considering the change in flow rate inside the membrane filament due to permeation, the coefficient of friction is... f φ100% The following modified Darcy-Weisbach formula is used for calculation:

[0048] in, ρg This represents the density of the gas inside the membrane filament.

[0049] II. Statistics on Leakage Points in Industrial Membrane Module Coatings like Figure 3 As shown, thousands of membrane fibers are fixed with resin between the end caps at both ends of the industrial membrane module. The effective separation length of the industrial membrane module is the length of the membrane fibers between the end caps. Gas transmission within the effective separation length region requires crossing the membrane wall. For a single membrane fiber, the higher the selective layer coverage (i.e., the closer the selective layer coverage φ is to 100%), the lower the gas permeation flux of that fiber. For the entire industrial membrane module, the greater the proportion η of fully selectively coated membrane fibers (membrane fibers with a selective layer coverage φ of 100%) in the total number of membrane fibers, the lower the total gas permeation flux of the industrial membrane module.

[0050] Since the permeation flux of membrane fibers to gases (such as nitrogen or air, CO2, H2, etc.) differs by more than two orders of magnitude before and after the selective layer is coated, when the selective layer fails to completely cover the inner wall of the membrane substrate, the permeation flux of membrane fibers with different selective layer coverage will have a large difference.

[0051] Preferably, in this embodiment, this difference is utilized by applying a layer of surfactant to the cross-section of the hollow fiber membrane bundle at the upper end cap of the industrial membrane module, and then pumping air at a small vacuum and flow rate on the permeate side (permeate outlet) of the membrane module to observe the changes in the surfactant bubble film. If the bubble film remains stationary, it indicates that the selective layer is fully coated on the membrane fiber. If the bubble film is drawn into the membrane fiber tube and sinks, it indicates that the selective layer is not fully coated and there are coating leaks on the membrane fiber.

[0052] More preferably, during the evacuation operation, the pressure difference between the ambient pressure P0 and the pressure P3 at the permeate outlet is in the range of 5~15 kPa.

[0053] Preferably, considering the large total number of membrane fibers n in the industrial membrane module, this embodiment uses a sampling method to obtain the proportion η of membrane fibers with the selected layer fully coated in the total membrane fibers. When dividing the sampling area, this embodiment considers the symmetry and uniformity of the selected layer coverage, and divides the area into multiple fan-shaped regions of equal shape and area at the same dividing angle, such as... Figure 4 As shown, during the test, it is only necessary to randomly select 2 to 3 areas to count the number of bubbles that are drawn into the membrane filament tube within the selected areas and the total number of bubbles, and then η can be calculated.

[0054] III. Calculation of Selective Layer Coverage for Industrial Membrane Modules Preferably, this embodiment provides an industrial membrane module selective layer coverage testing subsystem, including an industrial membrane module, a feed gas control component, a permeate gas control component, and a residual gas measurement component; wherein, the feed gas inlet of the industrial membrane module is connected to the feed gas control component, the permeate gas outlet is connected to the permeate gas control component, and the residual gas outlet is connected to the residual gas measurement component.

[0055] like Figure 5 As shown, the feed gas control assembly includes a blower, a first flow meter, a first valve, and a first pressure gauge connected in sequence, with the first pressure gauge connected to the feed gas inlet of the industrial membrane module; the permeate gas control assembly includes a vacuum gauge, a third flow meter, and a vacuum pump connected in sequence, with the vacuum gauge connected to the permeate outlet of the industrial membrane module; and the residual gas measurement assembly includes a second pressure gauge and a second flow meter connected to the residual gas outlet.

[0056] In this embodiment, the inlet pressure P1 and flow rate Q1, the permeate gas outlet pressure P2 and flow rate Q2, and the permeate gas extraction pressure P3 and flow rate Q3 of the industrial membrane module can be tested and obtained through the industrial membrane module selective layer coverage testing subsystem. Based on this, the permeability coefficient α of the small-scale membrane module before and after membrane fiber coating has been obtained. φ0% and α φ100% and the coefficient of friction of the inner wall of the membrane fiber f φ100% By combining the proportion η of fully coated membrane fibers in the total membrane fibers of the industrial membrane module, and finally solving the material conservation equation, the friction pressure loss equation, and the permeation resistance loss equation, the average selective layer coverage φ of the membrane fibers with coating leaks in the industrial membrane module can be calculated.

[0057] Preferably, the calculation principle is as follows: Figure 6 As shown. Where Q 单,1,φ100% Q 单,2,φ100% Q 单,2,φ100% Q represents the flow rate of a single fully coated selective layer membrane fiber in an industrial membrane module during testing at the feed gas inlet side, permeate outlet side, and permeate outlet side, respectively; 单,1,φ Q 单,2,φ Q 单,2,φ These are the flow rates of a single membrane fiber with a selectivity layer coverage of φ in an industrial membrane module at the feed gas inlet side, permeate outlet side, and permeate outlet side, respectively. These six parameters are related to α. φ (Industrial membrane modules) are the common variables to be calculated in the system of equations. Calculate α. φ Then, the average selective layer coverage φ of the membrane fibers coating the leak points is calculated by using linear equations.

[0058] Specifically, the pressure difference between the intake pressure P1 and the ambient pressure P0 used in the measurement ranges from 20 to 100 kPa.

[0059] Example 2 This embodiment is based on embodiment 1: In this embodiment, the EX1 membrane filament of the pilot membrane assembly is a hollow fiber membrane substrate without a selective layer coating, while the EX2 and EX3 membrane filaments are hollow fiber membrane filaments with completely selective layer coatings but different lengths. Their respective operating and measurement parameters in the pilot membrane assembly test are shown in Table 1. The test was conducted in an indoor environment at room temperature (20°C) and normal pressure (101 kPa).

[0060] Table 1 - Test Operation Parameters and Calculation Results of Small-Scale Film Components

[0061] Verification Examples 1, 2, and 3 present the test parameters and calculation results for small-scale membrane modules EX1, EX2, and EX3, respectively. Table 1 shows the air permeability coefficient α of the small-scale membrane tubes before coating. φ0% It is 9.305×10 -5 Nm 3 / (s*m 2 *kPa), after the selective layer is fully coated, the air permeability coefficient α φ100% It is 7.559×10 -7 Nm 3 / (s*m 2 *kPa); Based on the pressure difference and flow rate at the inlet and outlet of the membrane fiber tube in the small-scale test membrane module, the coefficient of friction of the inner wall of the membrane fiber. f φ100% It is 2.247×10 -3 The basic parameters of the membrane fibers used in subsequent industrial membrane modules are consistent with those of the membrane fibers used in the pilot-scale membrane modules.

[0062] In this embodiment, industrial membrane modules No. 1 and No. 2 have the same specifications, each with a total of approximately 5159 membrane filament tubes, and the effective separation length of the membrane filaments between the end caps is 1 m. Both have completed the coating process. When performing a sampling method to count the proportion η of the membrane filaments with fully coated layers in the total membrane filaments, the statistical cross section is divided into 24 regions with equal shape and area. The test operation is carried out in an indoor environment with normal temperature (20°C) and normal pressure (101 kPa).

[0063] Table 2 shows the test operation parameters, calculated percentage of membrane fibers with complete selective layer coating η, and average selective layer coverage φ of membrane fibers with coating leaks when industrial membrane modules No. 1 and No. 2 were evaluated using the membrane coating effect evaluation scheme of Example 1. Table 2 - Test Operation Parameters and Calculation Results for Industrial Membrane Modules

[0064] Verification Examples 4 and 5 present the test results of Industrial Membrane Module 1 under different test operating conditions. In both tests, the percentage η of the membrane fibers completely coated by the selective layer was approximately 91%, and the average coverage φ of the selective layer on the leaking membrane fibers was approximately 96%, demonstrating that the method provided in Example 1 can obtain stable results under different test operating conditions. Verification Examples 6 and 7 present the test results of Industrial Membrane Module 2 under different test operating conditions. The results also remained stable in both tests, with the percentage η of the membrane fibers completely coated by the selective layer approximately 95% and the average coverage φ of the selective layer on the leaking membrane fibers approximately 99%.

[0065] If the quality control requirement is that "after the coating process, the proportion of leaky membrane fibers should not exceed 5%, and the average coverage φ of the selected layer for leaky membrane fibers should not be less than 98%", then under this standard, the coating of industrial membrane module No. 1 is unqualified, while the coating effect of industrial membrane module No. 2 meets the requirements. Therefore, this invention provides a quantitative evaluation index that is easy to apply in industrial applications for evaluating whether the coating process is qualified.

[0066] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0067] It should be noted that, for the sake of simplicity, the foregoing method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0068] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "install", and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a wired connection or a wireless connection.

Claims

1. A method for testing and calculating the effect of film coating, characterized in that, include: Small-scale membrane module testing: Tests were conducted on the membrane fibers of the small-scale membrane module before and after coating, and the physical performance parameters of the membrane fibers, including the permeation coefficient and the friction coefficient of the inner wall of the membrane fibers, were calculated. Statistics on Leaking Membrane Fibers in Industrial Membrane Modules: The percentage of membrane fibers with fully coated layers in industrial membrane modules is selected and statistically analyzed, and is recorded as the percentage of non-leaking membrane fibers. Selective layer coverage calculation for industrial membrane modules: Measure the fluid parameters at each port of the industrial membrane module, including the pressure and flow rate at the feed gas inlet, residual gas outlet, and permeate outlet; and combine the physical performance parameters of the membrane fibers with the proportion of non-leaking membrane fibers, simultaneously establish the material conservation equation, the frictional pressure loss equation, and the permeation resistance loss equation to calculate the average selective layer coverage of membrane fibers with coating leaks within the industrial membrane module.

2. The method for testing and calculating the film coating effect according to claim 1, characterized in that, The small-scale membrane assembly test includes tests performed before and after coating the membrane fibers, including: The gas in the feed gas cylinder is controlled by sequentially passing through the feed gas valve to adjust the flow rate, the feed gas flow meter to measure the flow rate q1, and the feed gas pressure gauge to measure the pressure p1, before entering the small-scale membrane module measuring device from the feed gas inlet. The small-scale membrane module measuring device is equipped with at least one membrane fiber. The portion of the feed gas that passes through the membrane fiber selective layer to reach the outside of the membrane fiber is permeate gas, and the portion of the feed gas that flows out from the permeate gas outlet through the inner pipeline of the membrane fiber is permeate gas. The permeate gas flow rate q2 is measured by the permeate gas flow meter, and the pressure difference Δp between the feed gas inlet and the permeate gas outlet is measured by the differential pressure gauge, thereby calculating the permeate gas outlet pressure p2. An inert purge gas is used to carry the permeate gas through the membrane fibers out of the small-scale membrane module measuring device. During this process, the inert purge gas from the purge gas cylinder has its flow rate regulated by the purge gas valve and its flow rate q measured by the purge gas flow meter. 吹扫 It then enters the purge gas inlet of the small test membrane module measuring device, carries out the residual gas, and flows out from the residual gas outlet; After the permeate gas passes through a permeate pressure gauge (pressure p3) and a permeate flow meter (flow rate q3), it enters a gas detector to measure the proportion y of non-purge gas components in the permeate gas. 渗 .

3. The method for testing and calculating the film coating effect according to claim 2, characterized in that, In the small-scale membrane assembly test, the physical performance parameters of the membrane fibers are calculated, including: The permeability coefficient α before and after coating was calculated using the permeation resistance loss relationship equation. φ0% and α φ100% : In this context, the superscript "*" indicates measurement results obtained directly from hollow fiber membrane substrates without a selection layer coating; l The length of the membrane fibers in the small-scale membrane module. d The diameter of the membrane fibers in the small-scale membrane module; The coefficient of friction of the inner wall of the fully coated membrane fiber was calculated using the modified Darcy-Weisbach formula. f φ100% : in, ρ g This represents the density of the gas inside the membrane filament.

4. The method for testing and calculating the film coating effect according to claim 1, characterized in that, When calculating the leakage points of the membrane fibers in the industrial membrane module, the method for determining whether the membrane fibers in the selected layer are fully coated includes: applying a layer of surfactant to the cross-section of the hollow fiber bundle at the upper end cap of the industrial membrane module, and then pumping air on the permeate side of the membrane module at a preset vacuum degree and flow rate, and observing the changes in the surfactant bubble film; among them, the membrane fibers that remain stationary are those with fully coated layers, and the membrane fibers that sink into the membrane fiber tube are those with incomplete coating and leakage points.

5. The method for testing and calculating the film coating effect according to claim 4, characterized in that, When calculating the leakage points of the membrane fibers coated in the industrial membrane module, the proportion of membrane fibers with fully coated layers in the total number of membrane fibers is sampled and counted. This includes: based on the symmetry and uniformity of the coverage of the selected layer, the sampling area is divided into multiple fan-shaped areas of equal shape and area at the same dividing angle; during the statistics, a portion of the area is randomly selected for statistics, and the number and total number of membrane fibers that are drawn into the membrane fiber tube within the selected area are calculated, thereby calculating the proportion η of the membrane fibers with fully coated layers in the total number of membrane fibers.

6. The method for testing and calculating the film coating effect according to claim 1, characterized in that, In the small-scale membrane module test, the length of the membrane fiber to be tested is 0.08~0.25m. The differential pressure meter range is selected according to the different lengths of the membrane fiber to be tested. For each 0.1m membrane fiber length, the maximum range of the differential pressure meter is selected as 100~200 Pa.

7. The method for testing and calculating the film coating effect according to claim 1, characterized in that, In the statistics of leakage points of the industrial membrane module, after applying a layer of surfactant to the cross section of the hollow fiber membrane bundle at the upper end cap of the industrial membrane module, the pressure difference between the ambient pressure P0 and the pressure P3 at the permeate outlet during the pumping operation is 5~15 kPa. In the calculation of the selective layer coverage of the industrial membrane module, the pressure difference between the inlet pressure P1 and the ambient pressure P0 used when measuring the fluid parameters at each port of the industrial membrane module is in the range of 20~100 kPa.

8. A film coating effect testing system, used in the film coating effect testing and calculation method as described in claim 1, characterized in that, The membrane coating effect testing system includes a small-scale membrane component testing subsystem, which includes a small-scale membrane component measuring device, a feed gas input component, a purge gas input component, a permeate gas measuring component, a differential pressure gauge, and a residual gas flow meter. The small-scale membrane assembly measuring device is equipped with at least one membrane fiber. The portion of the feed gas that passes through the membrane fiber selective layer and reaches the outside of the membrane fiber is permeate gas, and the portion of the feed gas that flows out from the permeate gas outlet through the inner tube of the membrane fiber is permeate gas. The feed gas inlet of the small test membrane assembly measuring device is connected to the feed gas input assembly and the first end of the differential pressure gauge, the purge gas inlet is connected to the purge gas input assembly, the permeate gas outlet is connected to the permeate gas measuring assembly, and the residual gas outlet is connected to the second end of the differential pressure gauge and the residual gas flow meter.

9. The film coating effect testing system according to claim 8, characterized in that, The feed gas input assembly includes a feed gas cylinder, a feed gas valve, a feed gas flow meter, and a feed gas pressure gauge connected in sequence, with the feed gas pressure gauge connected to the feed gas inlet; The purge gas input assembly includes a purge gas cylinder, a purge gas valve, and a purge gas flow meter connected in sequence, with the purge gas flow meter connected to the purge gas inlet; The permeate gas measurement assembly includes a permeate gas pressure gauge, a permeate gas flow meter, and a gas detector connected in sequence, with the permeate gas pressure gauge connected to the permeate gas outlet.

10. A film coating effect testing system, used in the film coating effect testing and calculation method as described in claim 1, characterized in that, The membrane coating effect testing system includes an industrial membrane module selective layer coverage testing subsystem, which includes an industrial membrane module, a feed gas control component, a permeate gas control component, and a residual gas measurement component. The feed gas inlet of the industrial membrane module is connected to the feed gas control component, the permeate outlet is connected to the permeate control component, and the residual gas outlet is connected to the residual gas measurement component. The feed gas control assembly includes a blower, a first flow meter, a first valve, and a first pressure gauge connected in sequence, with the first pressure gauge connected to the feed gas inlet of the industrial membrane module; The permeate control assembly includes a vacuum gauge, a third flow meter, and a vacuum pump connected in sequence, with the vacuum gauge connected to the permeate outlet of the industrial membrane module; The residual gas measurement assembly includes a second pressure gauge and a second flow meter connected to the residual gas outlet.

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