High-efficiency precise filtering device and filtering method based on gradient aperture ceramic membrane

Abstract

The invention relates to the technical field of precise liquid separation, and discloses an efficient precise filtering device based on a gradient aperture ceramic membrane and a filtering method.The efficient precise filtering device based on the gradient aperture ceramic membrane comprises a gradient aperture ceramic membrane assembly which is formed by stacking at least three ceramic membrane layers with different apertures, along the fluid filtering direction (from the feeding side to the permeation side), the pore diameter is gradually reduced layer by layer (for example, the pore diameter of the outer layer is 5-10 micrometers, the pore diameter of the middle layer is 1-5 micrometers, and the pore diameter of the inner layer is 0.1-1 micrometer), a gradual change buffer layer (the gradient change rate of the pore diameter is smaller than or equal to 0.5 / micrometer) is arranged in a pore diameter transition area of every two adjacent membrane layers, and the ceramic membrane base body is made of an aluminum oxide-zirconium oxide composite material. Through a gradual change buffer layer and a co-firing process, pore diameter transition of adjacent membrane layers is smooth (the change rate is smaller than or equal to 0.5 / mu m), a filtering bottleneck is avoided, the overall flux is improved by 20%-30% compared with that of a traditional gradient membrane, particulate matter attachment is reduced through a nano TiO2 coating, and the membrane surface pollution rate is reduced by 40% or above in cooperation with high shear force (the flow speed is larger than or equal to 2 m / s) of a cross-flow mode; and the continuous operation period is prolonged to more than two times of that of the traditional device.

Description

Technical Field

[0001] This invention relates to the field of liquid precision separation technology, specifically to a high-efficiency precision filtration device and filtration method based on a gradient pore size ceramic membrane. Background Technology

[0002] This invention relates to a high-efficiency precision filtration device and method based on gradient pore size ceramic membranes. The device utilizes a ceramic membrane with a gradually changing pore size (gradient distribution) structure from the outside to the inside or from the inside to the outside as the core filtration medium. By progressively intercepting particles of different sizes, it achieves efficient and precise separation and filtration. The device typically includes modules such as membrane modules, a feed system, a pressure control system, and a cleaning system. Employing cross-flow filtration or dead-end filtration methods, it effectively removes particulate matter, colloids, microorganisms, and macromolecular impurities from solutions with low energy consumption and high flux. It is suitable for high-precision liquid separation requirements in chemical, pharmaceutical, environmental, and food industries. Furthermore, it possesses good chemical stability, thermal stability, and antifouling properties, is easy to clean and regenerate, and can operate stably for extended periods.

[0003] In existing technologies, high-efficiency precision filtration devices and methods based on gradient pore size ceramic membranes have been applied to some extent in chemical, pharmaceutical, environmental protection, and food industries. These filtration devices typically employ gradient ceramic membranes with pore sizes that gradually change from the outside to the inside or from the inside to the outside, aiming to improve filtration accuracy and efficiency by progressively intercepting particles of different sizes. However, existing technologies still have the following shortcomings:

[0004] First, the existing gradient pore size ceramic membranes have complex manufacturing processes, and the pore size gradient distribution is difficult to control precisely, resulting in an uneven transition between membrane layers and easy formation of filtration bottlenecks or local blockages, affecting the overall filtration flux and separation effect. Second, some devices do not fully consider membrane fouling and concentration polarization in their design. After long-term operation, particulate matter easily accumulates on the membrane surface, causing a significant increase in filtration resistance, severe flux attenuation, and greater difficulty in cleaning and regeneration, affecting the continuous and stable operation and service life of the device.

[0005] Furthermore, existing filtration methods mostly employ a single cross-flow or dead-end filtration mode, lacking an intelligent control strategy that adaptively adjusts flow rate, pressure, and filtration mode based on the characteristics of the feed liquid. This results in difficulty in achieving both filtration efficiency and separation accuracy under different operating conditions, leading to poor adaptability. In addition, some gradient pore size ceramic membranes lack sufficient chemical and thermal stability in harsh environments such as high temperature, strong acid and alkali, or organic solvents, limiting their application in a wider range of industrial scenarios.

[0006] Therefore, we propose a high-efficiency precision filtration device and filtration method based on gradient pore size ceramic membranes. Summary of the Invention

[0007] To achieve the above objectives, the present invention provides the following technical solution: a high-efficiency precision filtration device based on a gradient pore size ceramic membrane, comprising:

[0008] Gradient pore size ceramic membrane module: It is composed of at least three ceramic membrane layers with different pore sizes stacked together. The pore size decreases layer by layer along the fluid filtration direction (from the feed side to the permeate side) (e.g., outer layer 5-10 μm → middle layer 1-5 μm → inner layer 0.1-1 μm). The pore size transition zone between adjacent membrane layers is provided with a gradient buffer layer (pore size gradient change rate ≤0.5 / μm). The ceramic membrane substrate is an alumina-zirconia composite material (mass ratio 7:3-9:1), and the surface is loaded with a nano-scale titanium dioxide (TiO2) anti-fouling coating.

[0009] Multi-mode flow channel system: includes cross-flow channel (an annular flow channel is formed between the outside of the membrane module and the shell, with a flow velocity of 0.5 to 3 m / s) and dead-end flow channel (axially connected to the center of the membrane module, which is switched by a valve), and is connected to the feed pipeline through a three-way valve. Single mode or combination mode can be selected according to the working conditions.

[0010] Intelligent control unit: integrates a pressure sensor (monitoring the pressure difference before / after the membrane), a turbidity sensor (detecting the concentration of suspended solids in the permeate), a flow meter, and a PLC controller, for real-time data acquisition and automatic adjustment of feed pressure (0.1-0.8 MPa), transmembrane pressure difference (0.05-0.3 MPa), and flow rate;

[0011] Online cleaning system: includes backflushing pipeline (connected to the permeate outlet for backflushing the membrane surface), chemical cleaning agent storage tank (for storing weak acid / weak alkali solutions), and pulse jet device (for removing stubborn contaminants through intermittent high-pressure pulses).

[0012] Preferably, the thickness of the gradient buffer layer is 50-200 μm, and it is prepared by a gradient co-firing process (by pressing ceramic powders of different particle sizes into layers according to pore size requirements and then co-firing them) to ensure that there are no sharp interfaces between adjacent film layers.

[0013] Preferably, the coating thickness is 10-50 nm, and it is loaded onto the ceramic membrane surface by the sol-gel method, which can reduce the affinity between particulate matter and the membrane surface and inhibit biofilm adhesion.

[0014] Preferably, the three-way valve is linked to the PLC controller. When the particulate matter concentration in the feed liquid is >1000mg / L, it automatically switches to cross-flow mode (flow rate ≥2m / s), and when the particulate matter concentration is <100mg / L, it switches to dead-end mode (to reduce energy consumption).

[0015] Preferably, the PLC controller has a pre-stored differential pressure threshold (e.g., 0.3 MPa) and a permeate turbidity threshold (e.g., <5 NTU). When the real-time differential pressure exceeds the threshold, a backwashing procedure is triggered, and when the permeate turbidity exceeds the standard, chemical cleaning is initiated.

[0016] Preferably, the pulse jet device has a jet frequency of 1 to 5 times / minute, a single pulse pressure of 0.5 to 1.2 MPa, and a duration of 0.5 to 2 seconds.

[0017] A high-efficiency precision filtration method based on gradient pore size ceramic membranes includes the following steps:

[0018] S1: Pretreatment stage: The feed liquid to be filtered passes through a pre-filter (to remove large particulate impurities, particle size > 50μm) and then enters a buffer tank. The temperature of the feed liquid is adjusted to 20-60℃ by a temperature sensor (to avoid high temperature damage to the membrane structure).

[0019] S2: Mode selection and filtration stage: The intelligent control unit automatically selects the cross-flow mode (high concentration) or dead-end mode (low concentration) according to the particle concentration of the feed liquid. The feed liquid passes through the gradient pore size ceramic membrane module at a set flow rate (0.5~3m / s). Large particles are intercepted by the outer membrane, and small particles are successively intercepted by the middle and inner membranes. The permeate is collected from the center of the membrane module.

[0020] S3: Dynamic monitoring and adaptive adjustment stage: Real-time monitoring of in-membrane pressure (P1), post-membrane pressure (P2) and permeate turbidity (T). When ΔP = P1 - P2 > 0.2 MPa or T > 10 NTU, the PLC controller automatically adjusts the flow rate (increases by 10% to 20%) or triggers backwashing.

[0021] S4: Cleaning and maintenance stage: When ΔP > 0.3MPa or continuous operation time > 24 hours, perform backwashing (reverse flow of permeate for 1-3 minutes) and chemical cleaning (circulating and soaking in weak acid / weak alkali solution for 30-60 minutes) in sequence to restore membrane flux.

[0022] Preferably, the gradient pore size ceramic membrane module has a filtration accuracy of 0.1–10 μm (adjustable depending on the membrane layer combination), a retention rate of ≥99.5% for suspended solids (SS), and a retention rate of ≥99.9% for microorganisms such as Escherichia coli. The chemical cleaning agent is 0.5%–2% citric acid (pH = 2–3) or 0.1%–0.5% sodium hydroxide solution (pH = 10–11) by mass fraction. After cleaning, it is rinsed with deionized water until the pH is neutral.

[0023] Compared with the prior art, the present invention provides a high-efficiency precision filtration device and filtration method based on gradient pore size ceramic membrane, which has the following beneficial effects:

[0024] 1. This high-efficiency precision filtration device and filtration method based on gradient pore size ceramic membranes achieves smooth transition of pore size between adjacent membrane layers (change rate ≤ 0.5 / μm) through a gradient buffer layer and co-firing process, avoiding filtration bottlenecks. The overall flux is increased by 20% to 30% compared to traditional gradient membranes. The nano-TiO2 coating reduces particulate matter adhesion, and combined with the high shear force of the cross-flow mode (flow velocity ≥ 2m / s), the membrane fouling rate is reduced by more than 40%, and the continuous operation cycle is extended to more than twice that of traditional devices.

[0025] 2. This high-efficiency precision filtration device and method based on gradient pore size ceramic membrane intelligently switches between cross-flow / dead-end modes according to the feed concentration. It saves 30% to 50% energy at low concentrations and ensures high-precision separation (retention rate ≥99.5%) at high concentrations. By monitoring the differential pressure / turbidity in real time and automatically adjusting parameters, combined with backwashing and chemical cleaning, the membrane flux decay rate is <5% / cycle. It is suitable for high temperature (≤60℃) and weak acid / weak alkali environments (pH=3~11).

[0026] 3. This high-efficiency precision filtration device and filtration method based on gradient pore size ceramic membrane, with alumina-zirconia composite matrix that is resistant to high temperature (≤800℃) and corrosion (resistant to common acids and alkalis), broadens the application scenarios in chemically corrosive liquids (such as chlorine-containing wastewater). Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example

[0029] An embodiment of a high-efficiency precision filtration device and method based on a gradient pore size ceramic membrane: A high-efficiency precision filtration device based on a gradient pore size ceramic membrane includes:

[0030] Gradient pore size ceramic membrane module: It is composed of at least three ceramic membrane layers with different pore sizes stacked together. The pore size decreases layer by layer along the fluid filtration direction (from the feed side to the permeate side) (e.g., outer layer 5-10 μm → middle layer 1-5 μm → inner layer 0.1-1 μm). The pore size transition zone between adjacent membrane layers is provided with a gradient buffer layer (pore size gradient change rate ≤0.5 / μm). The ceramic membrane substrate is an alumina-zirconia composite material (mass ratio 7:3-9:1), and the surface is loaded with a nano-scale titanium dioxide (TiO2) anti-fouling coating.

[0031] Multi-mode flow channel system: includes cross-flow channel (an annular flow channel is formed between the outside of the membrane module and the shell, with a flow velocity of 0.5 to 3 m / s) and dead-end flow channel (axially connected to the center of the membrane module, which is switched by a valve), and is connected to the feed pipeline through a three-way valve. Single mode or combination mode can be selected according to the working conditions.

[0032] Intelligent control unit: integrates a pressure sensor (monitoring the pressure difference before / after the membrane), a turbidity sensor (detecting the concentration of suspended solids in the permeate), a flow meter, and a PLC controller, for real-time data acquisition and automatic adjustment of feed pressure (0.1-0.8 MPa), transmembrane pressure difference (0.05-0.3 MPa), and flow rate;

[0033] Online cleaning system: includes backflushing pipeline (connected to the permeate outlet for backflushing the membrane surface), chemical cleaning agent storage tank (for storing weak acid / weak alkali solutions), and pulse jet device (for removing stubborn contaminants through intermittent high-pressure pulses).

[0034] Specifically, the thickness of the gradient buffer layer is 50–200 μm, and it is prepared by a gradient co-firing process (by pressing ceramic powders of different particle sizes into layers according to pore size requirements and then co-firing them) to ensure that there are no sharp interfaces between adjacent film layers.

[0035] Preferably, the coating thickness is 10-50 nm, and it is loaded onto the ceramic membrane surface by the sol-gel method, which can reduce the affinity between particulate matter and the membrane surface and inhibit biofilm adhesion.

[0036] Specifically, the three-way valve is linked with the PLC controller. When the particulate matter concentration in the feed liquid is >1000mg / L, it automatically switches to cross-flow mode (flow rate ≥2m / s), and when the particulate matter concentration is <100mg / L, it switches to dead-end mode (to reduce energy consumption).

[0037] Specifically, the PLC controller has pre-stored differential pressure thresholds (e.g., 0.3 MPa) and permeate turbidity thresholds (e.g., <5 NTU). When the real-time differential pressure exceeds the threshold, the backwashing program is triggered, and when the permeate turbidity exceeds the standard, chemical cleaning is started.

[0038] Specifically, the pulse jet device has a jet frequency of 1 to 5 times per minute, a single pulse pressure of 0.5 to 1.2 MPa, and a duration of 0.5 to 2 seconds.

[0039] A high-efficiency precision filtration method based on gradient pore size ceramic membranes includes the following steps:

[0040] S1: Pretreatment stage: The feed liquid to be filtered passes through a pre-filter (to remove large particulate impurities, particle size > 50μm) and then enters a buffer tank. The temperature of the feed liquid is adjusted to 20-60℃ by a temperature sensor (to avoid high temperature damage to the membrane structure).

[0041] S2: Mode selection and filtration stage: The intelligent control unit automatically selects the cross-flow mode (high concentration) or dead-end mode (low concentration) according to the particle concentration of the feed liquid. The feed liquid passes through the gradient pore size ceramic membrane module at a set flow rate (0.5~3m / s). Large particles are intercepted by the outer membrane, and small particles are successively intercepted by the middle and inner membranes. The permeate is collected from the center of the membrane module.

[0042] S3: Dynamic monitoring and adaptive adjustment stage: Real-time monitoring of in-membrane pressure (P1), post-membrane pressure (P2) and permeate turbidity (T). When ΔP = P1 - P2 > 0.2 MPa or T > 10 NTU, the PLC controller automatically adjusts the flow rate (increases by 10% to 20%) or triggers backwashing.

[0043] S4: Cleaning and maintenance stage: When ΔP > 0.3MPa or continuous operation time > 24 hours, perform backwashing (reverse flow of permeate for 1-3 minutes) and chemical cleaning (circulating and soaking in weak acid / weak alkali solution for 30-60 minutes) in sequence to restore membrane flux.

[0044] Specifically, the filtration accuracy of the gradient pore size ceramic membrane module is 0.1–10 μm (adjustable depending on the membrane layer combination), the rejection rate of suspended solids (SS) is ≥99.5%, and the rejection rate of microorganisms such as Escherichia coli is ≥99.9%. The chemical cleaning agent is 0.5%–2% citric acid (pH=2–3) or 0.1%–0.5% sodium hydroxide solution (pH=10–11) by mass fraction. After cleaning, it is rinsed with deionized water until the pH is neutral.

[0045] Through the above technical solutions, this invention achieves a smooth transition in pore size between adjacent membrane layers (change rate ≤ 0.5 / μm) through a gradient buffer layer and co-firing process, avoiding filtration bottlenecks. The overall flux is increased by 20%–30% compared to traditional gradient membranes. The nano-TiO2 coating reduces particulate adhesion, and combined with the high shear force of the cross-flow mode (flow velocity ≥ 2 m / s), the membrane fouling rate is reduced by more than 40%, and the continuous operating cycle is extended to more than twice that of traditional devices. The cross-flow / dead-end mode is intelligently switched according to the feed concentration, saving 30%–50% energy at low concentrations and ensuring high-precision separation (retention rate ≥ 99.5%) at high concentrations. By automatically adjusting parameters through real-time monitoring of differential pressure / turbidity, combined with backwashing and chemical cleaning, the membrane flux decay rate is < 5% / cycle, making it suitable for high-temperature (≤ 60℃) and weakly acidic / weakly alkaline environments (pH = 3–11). The alumina-zirconia composite matrix is ​​resistant to high temperatures (≤800℃) and corrosion (resistant to common acids and alkalis), which broadens its application scenarios in corrosive chemical liquids (such as chlorine-containing wastewater).

[0046] 1. Gradient pore size ceramic membrane module (core filtration component)

[0047] (1) Membrane structure design

[0048] Total number of layers and pore size distribution: A three-layer composite structure is adopted, with the pore size decreasing layer by layer along the fluid filtration direction (from the feed side to the permeate side), specifically as follows:

[0049] Outer layer (first layer): pore size range of 5-10 μm (preferably 8 μm), used to intercept large particulate impurities (such as suspended matter, colloids, etc.);

[0050] Intermediate layer (second layer): pore size range 1-5μm (preferably 3μm), intercepting small and medium-sized particles (such as fine particles and some colloids);

[0051] Inner layer (third layer): pore size range of 0.1 to 1 μm (preferably 0.5 μm or 0.2 μm, adjusted according to the final accuracy requirements) to achieve high-precision separation (such as microorganisms and macromolecular solutes).

[0052] Gradient buffer layer: A gradient buffer layer with a thickness of 50-200 μm (preferably 100 μm) is set between adjacent film layers. It is prepared by a gradient co-firing process. Ceramic powders of different particle sizes (such as α-Al2O3 and ZrO2 micro powder mixed in proportion, with the particle size decreasing from the outer layer to the inner layer) are layered and pressed, and then co-fired at 1400-1600℃ to ensure a smooth transition of pore size (the pore size change rate between adjacent layers is ≤0.5 / μm to avoid local blockage caused by sharp interfaces).

[0053] (2) Membrane substrate and antifouling coating

[0054] The matrix material is an alumina (Al2O3)-zirconia (ZrO2) composite ceramic with a mass ratio of 7:3 to 9:1 (preferably 8:2), which has both high mechanical strength (compressive strength ≥30MPa) and thermal stability (temperature resistance ≤800℃).

[0055] Antifouling coating: Nanoscale titanium dioxide (TiO2, particle size 10-50 nm) is loaded onto the membrane surface via a sol-gel method, with a coating thickness of 10-50 nm (preferably 30 nm). The hydrophobicity of TiO2 reduces the affinity between particulate matter and the membrane surface, while its photocatalytic performance (if further enhanced by UV) can inhibit biofilm adhesion, further reducing pollution.

[0056] (3) Membrane module encapsulation

[0057] The membrane module can be a tubular structure (facilitating the formation of cross-flow channels) or a flat sheet structure (suitable for small-scale applications). This embodiment uses a tubular membrane module as an example:

[0058] The membrane tube has an inner diameter of 20–30 mm, a length of 500–1000 mm, and an effective filtration area of ​​0.1–0.5 m². 2 ;

[0059] The outer layer of the membrane tube is the feed side (high particulate matter side), and the inner layer is the center permeate side (collecting clean permeate).

[0060] 2. Multi-mode flow channel system (adaptable to different working conditions)

[0061] (1) Cross-flow channel (suitable for high-concentration liquids)

[0062] Structure: An annular flow channel (10-30 mm wide) is formed between the outer side of the membrane module and the device housing. The feed liquid flows over the membrane surface at high speed in the tangential direction (flow velocity 0.5-3 m / s, preferably 2-3 m / s). The shear force generated can effectively reduce the deposition of particulate matter on the membrane surface.

[0063] Flow rate control: The flow rate is adjusted by the feed pump (frequency control) to ensure that the flow rate meets the anti-pollution requirements (flow rate ≥2m / s at high concentrations).

[0064] (2) Dead-end flow channel (suitable for low-concentration liquids)

[0065] Structure: The feed liquid passes directly through the membrane module through the axial central tube (without annular flow channels), and all fluids pass vertically through the membrane layer (flow velocity 0.1-0.5 m / s), which is suitable for scenarios with low particulate matter concentration (<100 mg / L) and lower energy consumption.

[0066] Switching mechanism: The feed pipeline is connected via a three-way valve, and the intelligent control unit automatically selects the mode according to the particulate matter concentration (switches to cross flow when the concentration is >1000mg / L, and switches to dead end when the concentration is <100mg / L).

[0067] 3. Intelligent control unit (real-time monitoring and feedback control)

[0068] Sensor configuration:

[0069] Pressure sensors: installed on the feed side (pre-membrane pressure P1) and permeate side (post-membrane pressure P2) of the membrane module respectively, to monitor the transmembrane pressure difference ΔP = P1 - P2;

[0070] Turbidity sensor: Installed in the permeate outlet pipeline to detect the concentration of suspended solids in the permeate (turbidity unit NTU);

[0071] Flow meter: monitors feed flow rate and permeate flow rate;

[0072] Temperature sensor: monitors the temperature of the feed liquid (control range 20~60℃, to avoid high temperature damage to the membrane structure).

[0073] Control logic: The PLC controller has pre-stored thresholds (such as ΔP alarm value of 0.3MPa, and upper limit of turbidity of the permeate of 10NTU). When the real-time data exceeds the limit, automatic adjustment is triggered.

[0074] If ΔP > 0.2MPa (close to the threshold), gradually increase the feed rate (increase by 10% each time) or increase the cross-flow rate;

[0075] If the turbidity of the permeate is >10 NTU, the labeling membrane fouling will worsen, and backwashing should be initiated first.

[0076] If the continuous operating time exceeds 24 hours (regardless of whether the differential pressure exceeds the standard), chemical cleaning shall be performed.

[0077] 4. Online cleaning system (to restore membrane performance)

[0078] Backwashing module: The permeate outlet is connected to a backwashing pump, which can reverse the flow of permeate (from the inner layer of the membrane to the outer layer) to flush the membrane surface (pressure 0.5-1.2 MPa, duration 1-3 minutes) to remove particulate matter clogging the membrane pores.

[0079] Chemical cleaning module: includes a chemical storage tank (for storing weak acids such as 0.5%–2% citric acid (pH=2–3) and weak bases such as 0.1%–0.5% sodium hydroxide solution (pH=10–11)) and a circulation pump, which dissolves organic pollutants or inorganic scale by soaking (30–60 minutes).

[0080] Pulse jet device (optional enhancement function): During the backwashing stage, the cleaning effect is further enhanced by intermittent high-pressure pulses (frequency 1 to 5 times / minute, single pressure 0.5 to 1.2 MPa, duration 0.5 to 2 seconds), especially for stubborn contaminants (such as microbial films).

[0081] 5. Auxiliary preprocessing module

[0082] Pre-filter: Installed at the front end of the feed line, with a filtration accuracy of 50-100μm (such as a bag filter or screen), used to remove large particulate impurities (such as stones and fibers) and protect the ceramic membrane from mechanical damage.

[0083] Temperature control unit: The temperature of the feed liquid is controlled at 20-60℃ (optimal range 30-50℃) through a heat exchanger (such as a plate heat exchanger) to avoid thermal deformation of the ceramic membrane caused by high temperature (>80℃) or increase in viscosity of the feed liquid (increases filtration resistance) caused by low temperature (<20℃).

[0084] II. Specific Implementation Steps of the Filtering Method (Detailed with Examples)

[0085] Example 1: Chemical wastewater treatment (high concentration of suspended solids scenario)

[0086] Scene parameters:

[0087] Wastewater to be treated: contains suspended solids (SS) of 1500 mg / L, mainly composed of silt, rust and colloidal particles, pH = 6-8, temperature 30℃.

[0088] Target: Permeate SS ≤ 10 mg / L (industrial reuse standard).

[0089] Operating procedures:

[0090] Preprocessing stage:

[0091] The wastewater first passes through a pre-filter (50μm screen) to remove large particles (stones and debris >50μm), and the remaining liquid enters the buffer tank;

[0092] The temperature sensor detects the liquid temperature at 30℃ (meets the requirement of 20~60℃), so no additional heating / cooling is required.

[0093] Pattern selection and filtering stage:

[0094] The intelligent control unit detects that the SS of the feed liquid is 1500 mg / L (>1000 mg / L threshold) and automatically switches to cross-flow mode;

[0095] The feed liquid flows through the tubular membrane module (outer layer → middle layer → inner layer) at a flow rate of 2.5 m / s. Large particles (>8 μm) are intercepted by the outer membrane, medium and small particles (1~8 μm) are retained by the middle layer, and small particles (<1 μm) are filtered by the inner membrane.

[0096] The operating pressure is maintained at 0.5 MPa (the transmembrane pressure difference ΔP is initially 0.1 MPa), and the permeate is collected into a clean storage tank.

[0097] Dynamic monitoring and adaptive adjustment:

[0098] After 12 hours of operation, the membrane pressure difference ΔP increased to 0.28 MPa (close to the 0.3 MPa threshold), and the permeate turbidity increased to 12 NTU (>10 NTU threshold).

[0099] The PLC controller automatically triggers the backwashing program: the feed valve is closed, the backwashing pump is started, and the permeate backwashes the membrane surface at a pressure of 1.0 MPa for 2 minutes, reducing the pressure difference to 0.12 MPa;

[0100] After backwashing, filtration continued, but after 6 hours ΔP rose again to 0.25 MPa and the turbidity of the permeate was >10 NTU, triggering chemical cleaning: 1% citric acid solution (pH=2.5) was injected, and the membrane was circulated and soaked for 45 minutes. Then it was rinsed with deionized water until pH=7, and the membrane flux was restored to 95% of the initial value.

[0101] Execution result:

[0102] After 48 hours of continuous operation, the suspended solids (SS) in the permeate remained stable at 5–8 mg / L (retention rate ≥99.5%), with no microbial leakage (E. coli not detected).

[0103] Total flux attenuation rate < 8% / cycle (traditional devices typically > 20% / cycle).

[0104] Example 2: Fine filtration of pharmaceutical solutions (low-concentration aseptic scenario)

[0105] Scene parameters:

[0106] The solution to be filtered contains active ingredients (such as antibiotic solutions), SS = 80 mg / L, and needs to retain microorganisms (such as bacteria and spores). The target permeate turbidity is <2 NTU (meeting the sterility requirements of the Chinese Pharmacopoeia).

[0107] Operating procedures:

[0108] Preprocessing stage:

[0109] The liquid medicine is filtered through a pre-filter (10μm precision) to remove a small amount of particles, and the temperature is adjusted to 40℃ (optimal filtration temperature).

[0110] The intelligent control unit detects SS = 80mg / L (<100mg / L threshold) and automatically switches to dead-end mode.

[0111] Pattern selection and filtering stage:

[0112] The feed solution enters the membrane module directly through the axial central tube (without cross-flow shear), with an operating pressure of 0.3 MPa. The inner membrane (0.2 μm pore size) intercepts all bacteria (size > 0.5 μm) and large molecular impurities.

[0113] The turbidity was monitored in real time and found to be 1.5 NTU (<2 NTU), which meets the sterility requirements.

[0114] Cleaning and maintenance phase:

[0115] After 24 hours of continuous operation (even if the differential pressure does not exceed the limit), the PLC controller forcibly starts chemical cleaning: inject 0.5% sodium hydroxide solution (pH=11) and circulate for 30 minutes to dissolve any possible organic residues, then rinse with deionized water until pH=7;

[0116] After cleaning, the membrane flux recovery rate is >98%, and the next batch of filtration can continue.

[0117] Execution result:

[0118] The microbial retention rate of the permeate is ≥99.99% (passing the sterility test), and the loss rate of the effective components of the drug solution is <0.5% (no adsorption loss).

[0119] Single-batch filtration time is reduced by 30% (energy saving compared to cross-flow mode).

[0120] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency precision filtration device based on gradient-pore ceramic membrane, characterized in that: Comprise: Gradient-pore ceramic membrane module: composed of at least three layers of ceramic membranes with different pore sizes, the pore size decreases layer by layer along the fluid filtration direction (from the feed side to the permeate side) (for example, outer layer 5-10 μm→ middle layer 1-5 μm→ inner layer 0.1-1 μm), and the pore size transition zone of adjacent membrane layers is provided with a gradual buffer layer (pore size gradient change rate ≤0.5 / μm), and the ceramic membrane substrate is alumina-zirconia composite material (mass ratio 7:3-9:1), and the surface is loaded with nano-sized titanium dioxide (TiO2) anti-pollution coating; Multi-mode flow channel system: contains cross-flow flow channel (annular flow channel formed between the outer side of the membrane module and the shell, flow velocity 0.5-3 m / s) and dead-end flow channel (axial through the center of the membrane module, switched by valve), connected with the feed pipeline through a three-way valve, can select single mode or combined mode according to working conditions; Intelligent control unit: integrated with pressure sensor (monitoring the pressure difference before / after the membrane), turbidity sensor (detecting the suspended solids concentration of the permeate), flow meter and PLC controller, for real-time data acquisition and automatic adjustment of feed pressure (0.1-0.8 MPa), transmembrane pressure difference (0.05-0.3 MPa) and flow rate; Online cleaning system: including backwash pipeline (connecting the permeate outlet to reverse flush the membrane surface), chemical cleaning agent storage tank (storing weak acid / weak base solution) and pulse jet device (removing stubborn pollutants by intermittent high-pressure pulse).

2. The high-efficiency precision filtration device based on gradient-pore ceramic membrane according to claim 1, characterized in that: The thickness of the gradual buffer layer is 50-200 μm, which is prepared by gradient co-burning process (different particle size ceramic powder is layered and pressed according to the pore size requirement and then co-burned), ensuring that there is no sharp interface between adjacent membrane layers.

3. The high-efficiency precision filtration device based on gradient-pore ceramic membrane according to claim 1, characterized in that: The coating thickness is 10-50 nm, which is loaded on the surface of the ceramic membrane by sol-gel method, which can reduce the affinity of particulate matter with the membrane surface and inhibit the attachment of biofilm.

4. The high-efficiency precision filtration device based on gradient-pore ceramic membrane according to claim 1, characterized in that: The three-way valve is linked with the PLC controller, which automatically switches to cross-flow mode (flow velocity ≥2 m / s) when the particle concentration in the feed liquid is >1000 mg / L, and switches to dead-end mode (reducing energy consumption) when the particle concentration is <100 mg / L.

5. The high-efficiency precision filtration device based on gradient-pore ceramic membrane according to claim 1, characterized in that: The PLC controller has pre-stored pressure difference threshold (such as 0.3 MPa) and permeate turbidity threshold (such as <5 NTU), and triggers the backwash program when the real-time pressure difference exceeds the threshold, and starts chemical cleaning when the permeate turbidity exceeds the standard.

6. The high-efficiency precision filtration device based on gradient-pore ceramic membrane according to claim 1, characterized in that: The pulse jet device has a jet frequency of 1-5 times / minute, a single pulse pressure of 0.5-1.2 MPa, and a duration of 0.5 s-2 s.

7. A high efficiency precision filtration method based on gradient-pore ceramic membranes, characterized by: Comprise the following steps: S1: pretreatment stage: the filtered liquid enters the buffer tank after passing through the pre-filter (removing large particle impurities, particle size >50 μm), and the liquid temperature is adjusted to 20-60 ℃ by the temperature sensor (to avoid high temperature damage to the membrane structure); S2: mode selection and filtration stage: the intelligent control unit automatically selects cross-flow mode (high concentration) or dead-end mode (low concentration) according to the particle concentration of the feed liquid, the feed liquid passes through the gradient-pore ceramic membrane module at a set flow rate (0.5-3 m / s), large particles are intercepted by the outer layer membrane, small particles are sequentially intercepted by the middle layer and inner layer membrane, and the permeate is collected from the center of the membrane module; S3: Dynamic monitoring and adaptive adjustment phase: real-time monitoring of pre-membrane pressure (P1), post-membrane pressure (P2) and permeate turbidity (T), when ΔP = P1-P2>0.2MPa or T>10NTU, PLC controller automatically adjusts the flow rate (increases by 10%-20%) or triggers backwash; S4: cleaning and maintenance phase: when ΔP>0.3MPa or continuous operation time>24 hours, backwash (permeate reverse flow for 1-3 minutes) and chemical cleaning (weak acid / weak base solution circulation immersion for 30-60 minutes) are performed in turn to restore membrane flux.

8. The high-efficiency precision filtration method based on gradient-pore ceramic membrane according to claim 7, characterized in that: The gradient-pore-size ceramic membrane module has a filtration accuracy of 0.1-10μm (adjustable according to membrane layer combination), a suspended solid (SS) retention rate of ≥99.5%, and a microorganism such as Escherichia coli retention rate of ≥99.9%, the chemical cleaning agent is 0.5%-2% citric acid (pH=2-3) or 0.1%-0.5% sodium hydroxide solution (pH=10-11) in mass fraction, and after cleaning, the module is rinsed with deionized water until neutral pH.