Preparation method for automatically controlling filtration of biomass adhesive

Abstract

The invention discloses an automatic control filtering preparation method of a biomass adhesive, which realizes efficient and continuous production through the synergistic effect of a three-stage gradient filtering system and an intelligent feedback control technology. The creatively designed corrugated filter screen and the self-cleaning ceramic membrane remarkably improve the filtering precision and flux, and by combining a dynamic parameter adjustment algorithm, the particle size D90 of the product is smaller than or equal to 1.8 microns, and the viscosity fluctuation is smaller than + / -2%. And compared with the traditional process, the energy consumption is reduced by more than 40%, and the method is suitable for industrial production of the environment-friendly adhesive.

Description

Technical Field

[0001] The present invention belongs to the technical field of bio-based material processing, and particularly relates to a continuous production method of biomass adhesives based on an intelligent control system, especially for the automated control of the multi-stage filtration process in the preparation of adhesives. Through an innovative three-stage gradient filtration system and dynamic parameter adjustment technology, the present invention significantly improves filtration efficiency and product quality, and is applicable to the industrial production of biomass adhesives such as starch-based and lignin-based adhesives. Background Art

[0002] The current production of biomass adhesives faces the following technical bottlenecks:

[0003] 1. Unstable filtration accuracy: The traditional process uses single-stage filtration, and manual operation leads to fluctuations in filtration accuracy (for example, the filtration error of a 50μm mesh filter is up to ±10μm). Particulate impurities that are not completely removed (particle size > 5μm) often remain in the product, affecting the bonding performance of the adhesive.

[0004] 2. Low production efficiency: Intermittent production requires frequent shutdowns for filter screen cleaning (once every 2 - 3 hours), the equipment utilization rate is less than 60%, and the throughput is usually less than 5m 3 / h.

[0005] 3. High energy consumption and cost: The steam consumption is as high as 2.8 - 3.5 tons per ton of product, and manual parameter adjustment errors easily lead to raw material waste, increasing the production cost by more than 20%.

[0006] Existing improvement technologies such as CN20201023888.1 use centrifugal filtration instead of pressure filtration. Although the throughput is increased to 8m 3 / h, high-speed centrifugation causes damage to the colloid structure, and the viscosity drops by more than 30%; the multi-layer filter screen design proposed in patent CN20192045789.X improves the filtration accuracy, but the frequency of filter screen blockage increases, and it is necessary to stop for backwashing every 1.5 hours, making continuous production difficult. Therefore, there is an urgent need to develop an automated filtration process with high efficiency, stability, and low energy consumption. Summary of the Invention

[0007] 1. Technical Solution

[0008] The present invention proposes a preparation method integrating three-stage gradient filtration and intelligent feedback control, including the following core modules:

[0009] Raw material pretreatment unit: Homogenize biomass raw materials (such as starch, lignin) through a twin-screw extrusion modification device;

[0010] Three-stage gradient filtration unit: Sequentially configure a 50μm stainless steel filter screen, a 10μm ceramic membrane, and a 2μm polymer ultrafiltration membrane, and set buffer tanks after each stage of filtration;

[0011] Intelligent control system: Dynamically adjust the filtration parameters based on real-time pressure, turbidity, and flow rate data, and predict the risk of filter mesh clogging.

[0012] 2. Innovation points

[0013] (1) Three-stage gradient filtration architecture

[0014] Primary filtration: Adopt a corrugated stainless steel filter mesh with anti-clogging design (pore size 50μm), install it at an angle of 30° to extend the impurity accumulation time, and the working pressure is 0.15 - 0.25 MPa;

[0015] Secondary filtration: Configure a ceramic membrane module with self-cleaning function (pore size 10μm), and remove the deposits on the membrane surface through periodic reverse pulse airflow (0.5 - 0.8 MPa);

[0016] Tertiary filtration: Use a high-temperature resistant polyethersulfone ultrafiltration membrane (retention molecular weight 5000 Da), adopt a cross-flow filtration mode, and the tangential flow velocity is 1.0 - 1.5 m / s to reduce membrane fouling.

[0017] (2) Intelligent control strategy

[0018] Multi-parameter feedback mechanism: Deploy high-precision pressure sensors (accuracy ±0.1%), on-line turbidimeters (detection range 0 - 100 NTU) and electromagnetic flow meters at the inlet and outlet of each filtration unit;

[0019] Dynamic adjustment algorithm: When the filtration pressure difference of a certain stage exceeds the set threshold (such as ΔP > 0.08 MPa for primary filtration), the system automatically reduces the feed flow rate and triggers local backwashing;

[0020] Fault warning system: Establish a filter mesh life prediction model based on historical data, and prompt to replace or deeply clean the filter element 12 hours in advance.

[0021] (3) Process parameter optimization

[0022] Temperature control: Set the three-stage filtration temperature gradient as 55°C → 65°C → 60°C to reduce the colloid viscosity and inhibit the growth of microorganisms;

[0023] Backwashing strategy: The primary filter mesh is subjected to 0.6 MPa air pulse backwashing every 30 minutes (lasting for 5 seconds), and the secondary ceramic membrane starts ultrasonic-assisted cleaning every 4 hours (frequency 40 kHz, duration 10 minutes);

[0024] Filter aid addition: Adopt a composite filter aid of diatomaceous earth and activated carbon (mass ratio 3:1), and the addition amount is only 60% of the traditional process to reduce the residue risk.

[0025] 3. Technical effects

[0026] Filtration efficiency: The continuous operating flux is stable at 10 m 3 / h or above, a 200% improvement over the traditional process;

[0027] Product quality: The colloid particle size D90 ≤ 1.8 μm, the viscosity fluctuation < ±2%, and the free formaldehyde content is not detected;

[0028] Energy consumption reduction: The steam consumption per ton of product is reduced to 1.6 tons, and the power consumption is reduced by 40%;

[0029] Maintenance cost: The service life of the filter screen is extended to 1500 hours, and the cleaning frequency is reduced by 70%. Specific implementation mode

[0030] Example 1: Preparation of corn starch-based adhesive

[0031] 1. Raw material pretreatment

[0032] Take 100 kg of corn starch (amylose content ≥ 28%), add 400 kg of deionized water, and stir and mix; input the mixed solution into a twin-screw extrusion modifier (length-diameter ratio 48:1), and set the temperature gradient to 60 °C (feeding section) → 75 °C (compression section) → 65 °C (homogenization section);

[0033] Add 0.3 kg of α-amylase and carry out enzymatic hydrolysis reaction at 55 °C for 2 hours to obtain a homogeneous colloid.

[0034] 2. Gradient filtration process

[0035] Primary filtration: Use a 50 μm corrugated stainless steel filter screen, initial pressure 0.18 MPa, flow rate 12 m 3 / h; when the pressure difference rises to 0.08 MPa, automatically start gas pulse backwashing (0.6 MPa, lasting for 5 seconds);

[0036] Secondary filtration: The working pressure of the ceramic membrane module is 0.35 MPa, start ultrasonic cleaning (40 kHz, 10 minutes) every 4 hours, and the flux is maintained at 9 m 3 / h;

[0037] Tertiary filtration: The cross-flow velocity of the ultrafiltration membrane is 1.2 m / s, the transmembrane pressure is 0.45 MPa, and the on-line turbidimeter monitors in real time. When the turbidity > 3 NTU, trigger cyclic filtration.

[0038] 3. Quality inspection

[0039] Viscosity: 1200 ± 20 cP (25 °C, rotational viscometer);

[0040] Solid content: 42.5 ± 0.3% (determined by drying method);

[0041] Particle size distribution: D50 = 0.8 μm, D90 = 1.7 μm (laser particle size analyzer);

[0042] Environmental protection indicators: Free formaldehyde not detected (GB / T 17657-2013), VOC emission < 50 μg / m 3 .

[0043] Example 2: Continuous production of lignin-based adhesive

[0044] 1. Raw material treatment

[0045] Alkaline lignin (solid content 55%) is ultrafinely ground to D50 = 10 μm and mixed with deionized water at a ratio of 1:3; 12 kg of sodium sulfite is added for sulfonation modification, and the reaction is carried out at 85 °C for 1.5 hours, and the pH value is adjusted to 9.0 - 9.5.

[0046] 2. Application of intelligent control

[0047] Dynamic regulation: When the pressure at the inlet of the secondary filter exceeds 0.38 MPa, the system automatically reduces the feed flow rate from 10 m 3 / h to 8 m 3 / h and starts ultrasonic cleaning 5% in advance;

[0048] Fault warning: When the flux of the tertiary ultrafiltration membrane continuously decreases by > 5% for 2 hours, the system alarms to prompt chemical cleaning.

[0049] 3. Performance data

[0050] Gluing strength: 1.82 MPa (the standard requirement of GB / T 9846-2015 is ≥ 1.5 MPa);

[0051] Water resistance: No delamination after soaking in water for 72 hours (D4 grade standard);

[0052] Continuous operation: The flux decay rate < 3% after 72 hours without manual intervention.

[0053] The following is a comparative analysis table of the data of Example 1, Example 2 of the present invention, traditional adhesives and literature patents, and a comprehensive comparison is made in combination with experimental data and industry standards:

[0054]

Claims

1. A preparation method for automatic control filtration of a biomass adhesive, characterized in that It includes the following steps: (a) The biomass raw material is subjected to twin-screw extrusion modification treatment to obtain a uniform colloidal solution; (b) The colloidal solution is sequentially passed through a three-stage gradient filtration unit, and the pore sizes of the three-stage filtration unit are 50μm, 10μm, and 2μm respectively; (c) By real-time monitoring of the pressure, turbidity, and flow rate data of each filtration unit, the filtration parameters are dynamically adjusted and the backwashing program is triggered; (d) Based on the filtration efficiency prediction model, the addition amount of the filter aid and the cleaning cycle are optimized.

2. The method according to claim 1, wherein The three-stage gradient filtration unit includes: the primary filtration uses a corrugated stainless steel filter screen, which is installed at an inclination of 30°, and the working pressure is 0.15 - 0.25 MPa; the secondary filtration is equipped with a ceramic membrane module with ultrasonic cleaning function, and the backwashing pressure is 0.5 - 0.8 MPa; the tertiary filtration uses a cross-flow polyethersulfone ultrafiltration membrane, and the tangential flow velocity is 1.0 - 1.5 m / s.

3. The method according to claim 1, wherein The dynamic adjustment includes: when the pressure difference of any filtration unit exceeds the set threshold, the feed flow rate is automatically reduced by 10 - 30%; when the on-line turbidity value exceeds the standard continuously for 5 minutes, the circulating filtration mode is started.

4. The method according to claim 1, wherein The filter aid is a composite of diatomaceous earth and activated carbon with a mass ratio of 3:1, and the addition amount is 0.1 - 0.3% of the total mass of the colloid.

5. The method according to claim 1, wherein The backwashing program includes: the primary filter screen is subjected to air pulse backwashing every 30 minutes, the pressure is 0.6 MPa, and the duration is 3 - 8 seconds; the secondary ceramic membrane starts ultrasonic cleaning every 4 hours, the frequency is 40 kHz, and the duration is 8 - 12 minutes.

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