A device for recovering waste acid from a forming waste liquid of a latex thread production line

Abstract

The utility model discloses a kind of waste acid recovery devices in forming waste liquid of latex thread production line, including vacuum evaporation kettle, the top end of vacuum evaporation kettle is connected evaporative liquid condenser, evaporative liquid condenser connects evaporative liquid storage tank, evaporative liquid storage tank is connected with evaporator vacuum pump and evaporative liquid delivery pump, evaporative liquid delivery pump is connected with heat exchanger, heat exchanger connects heater, heater connects series permeation vaporization membrane assembly, the concentrated liquid outlet of series permeation vaporization membrane assembly is connected with heat exchanger, the permeation liquid outlet of series permeation vaporization membrane assembly is connected with permeation liquid condenser, permeation liquid condenser connects permeation liquid storage tank, permeation liquid storage tank is connected with permeation vaporization membrane vacuum pump and permeation liquid discharge pump.The utility model uses "vacuum evaporation-permeation vaporization membrane" coupling process, can break through the concentration and efficiency limit of traditional process, significantly reduce wastewater treatment load, wastewater COD value and processing cost, provide the upgrading scheme with economy and environmental protection for latex thread production industry.

Description

Technical Field

[0001] This utility model relates to the field of waste liquid utilization technology, and in particular to a device for recovering waste acid from the molding waste liquid of a latex filament production line. Background Technology

[0002] Latex filaments, as a natural rubber product, are primarily composed of cis-polyisoprene, possessing excellent elasticity, insulation, water resistance, plasticity, tensile strength, tear resistance, and abrasion resistance. After specific processing, they can also exhibit oil resistance, acid and alkali resistance, heat resistance, cold resistance, and pressure resistance. Furthermore, they exhibit excellent elasticity and are not easily deformed, making them widely used in textiles, apparel, medical and health products, and sporting goods. The production process of latex filaments uses latex as the main raw material, supplemented with more than twenty industrial raw materials such as titanium dioxide, zinc oxide, and sulfur. After stirring, homogenization, and filtration, the filaments are extruded to form a smooth linear cross-section. They are then placed in a coagulation bath containing a specific proportion of acetic acid, washed with water to remove the acetic acid, and subsequently dried, desulfurized, and pressed into strips.

[0003] The core of latex filament production is latex molding technology. The currently prevalent extrusion acid coagulation process is based on the principle of ion precipitation: positively charged cations in the acid solution neutralize negatively charged particles in the latex, causing the extruded latex to deposit into a film, transitioning from a fluid state to a gelled state. The current mainstream domestic isothermal and constant-pressure acetic acid coagulation extrusion method is characterized by high efficiency, low energy consumption, and excellent product appearance, making it a relatively advanced latex filament production process. However, this process still has significant drawbacks: the acid coagulation process generates large amounts of difficult-to-treat acidic wastewater, and traditional wastewater treatment methods are costly and prone to secondary pollution. Therefore, developing green and efficient acid recovery technologies to reduce raw material consumption and environmental pollution has become a key challenge for the latex filament industry to achieve sustainable development.

[0004] Existing technologies attempt to improve upon these methods but have significant limitations. For example, patent CN110776414A employs a secondary distillation technique, using ethyl acetate as an azeotropic agent to lower the boiling point of water and recover acetic acid. While suitable for large-scale production, this method is complex, energy-intensive, and difficult to handle in terms of residue. Patent CN210993066U separates acetic acid from water using a distillation column and an ester-water separator. Although the device is compact and highly integrated, its processing capacity is limited, its separation efficiency is low due to its reliance on azeotropic point differences, and its thermal energy utilization is insufficient. Patent CN211536588U uses a multi-layer tray (68 layers) and staggered design to improve gas-liquid contact efficiency. It is specifically designed for high-flow-rate waste acid. While it offers high mass transfer efficiency, it suffers from high maintenance costs, poor operational stability, and stringent requirements for raw materials. Utility Model Content

[0005] This invention aims to solve the technical problems of low waste acid recovery rate and high energy consumption in the existing technology, and provides a waste acid recovery device in the molding waste liquid of latex filament production line. By removing impurities and initially concentrating the waste acid through depressurized evaporation, and then combining it with deep dehydration through pervaporation membrane, the waste acid can be efficiently recovered and directly reused in the coagulation process, while significantly reducing the COD value of wastewater and treatment costs.

[0006] The technical solution of this utility model is: a device for recovering waste acid from the molding waste liquid of a latex filament production line, comprising a vacuum evaporator, the top of which is connected to an evaporating liquid condenser, the evaporating liquid condenser being connected to an evaporating liquid storage tank, the evaporating liquid storage tank being connected to an evaporator vacuum pump and an evaporating liquid delivery pump, the evaporating liquid delivery pump being connected to a heat exchanger, the heat exchanger being connected to a heater, the heater being connected to a series pervaporation membrane assembly, the concentrate outlet of the series pervaporation membrane assembly being connected to the heat exchanger, the permeate outlet of the series pervaporation membrane assembly being connected to a permeate condenser, the permeate condenser being connected to a permeate storage tank, and the permeate storage tank being connected to a pervaporation membrane vacuum pump and a permeate discharge pump.

[0007] Furthermore, the vacuum evaporator described in this utility model has a waste acid inlet on one side, an evaporator steam outlet at the top and an evaporator concentrate outlet at the bottom, the evaporator steam outlet is connected to the evaporator condenser, and a heating tube is provided inside the vacuum evaporator.

[0008] Furthermore, both the evaporator condenser and the permeate condenser in this invention are provided with a circulating cooling water inlet and a circulating cooling water outlet.

[0009] Furthermore, both the heating tube and the heater in this invention are provided with a steam inlet and a steam condensate outlet.

[0010] Furthermore, the series pervaporation membrane assembly described in this utility model includes a plurality of membrane assemblies connected in series, and the pervaporation membrane of each membrane assembly includes a support and a separation layer coated on the surface of the support.

[0011] Furthermore, in this invention, the support body is a porous ceramic tube, and the separation layer is a silicon oxide or zirconium oxide separation layer.

[0012] Furthermore, the porous ceramic tube in this invention has a pore size of 0.1-1 μm, and the separation layer has a thickness of 200-500 nm.

[0013] Compared with the prior art, this utility model has the following advantages: This utility model adopts a "reduced pressure evaporation-pervaporation membrane" coupled process. First, the bubble point of waste acid is reduced by reduced pressure evaporation, which initially purifies the waste acid and removes impurities such as salts and macromolecular organic matter (acid recovery rate of over 80%). Then, selective dehydration is carried out using a pervaporation membrane to increase the acid concentration to over 60% (acetic acid recovery rate of 99.9%). Finally, the recovered acid can be directly reused. The device using this utility model can break through the concentration and efficiency limitations of traditional processes, significantly reduce wastewater treatment load, wastewater COD value and treatment cost, and provide an upgrade solution for the latex filament production industry that is both economical and environmentally friendly. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] The components include: 1. Vacuum-reduced evaporator; 1a. Waste acid inlet; 1b. Steam outlet of evaporator; 1c. Concentrate outlet of evaporator; 1d. Heating tube; 2. Evaporate condenser; 3. Evaporate storage tank; 4. Vacuum pump of evaporator; 5. Evaporate transfer pump; 6. Heat exchanger; 7. Heater; 8. Series pervaporation membrane assembly; 9. Permeate condenser; 10. Permeate storage tank; 11. Pervaporation membrane vacuum pump; 12. Permeate discharge pump; A1. Steam inlet; A2. Steam condensate outlet; B1. Circulating cooling water inlet; B2. Circulating cooling water outlet. Detailed Implementation

[0016] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0017] Example: The accompanying drawings illustrate a specific embodiment of a waste acid recovery device from molding waste liquid in a latex filament production line according to this utility model. Figure 1 The system mainly includes a vacuum evaporator 1, with a waste acid inlet 1a on one side for introducing acidic wastewater. The top of the vacuum evaporator 1 has an evaporator steam outlet 1b, and the bottom has an evaporator concentrate outlet 1c for discharging residual evaporation liquid. The vacuum evaporator 1 contains a heating tube 1d, with a steam inlet A1 and a steam condensate outlet A2.

[0018] The steam outlet 1b of the evaporator is connected to the evaporator liquid condenser 2, which is equipped with a circulating cooling water inlet B1 and a circulating cooling water outlet B2.

[0019] The evaporator condenser 2 is connected to the evaporator storage tank 3. The evaporator storage tank 3 is connected to the evaporator vacuum pump 4 and the evaporator delivery pump 5. The evaporator storage tank 3 is used to store the evaporated crude acid liquid, and the evaporator delivery pump 5 is used to pump out the crude acid liquid.

[0020] The evaporator pump 5 is connected to a heat exchanger 6, which is connected to a heater 7. The heater 7 is equipped with a steam inlet A1 and a steam condensate outlet A2.

[0021] Heater 7 is connected to series pervaporation membrane module 8. The concentrate outlet of series pervaporation membrane module 8 is connected to heat exchanger 6. The permeate outlet of series pervaporation membrane module 8 is connected to permeate condenser 9. Permeate condenser 9 is provided with circulating cooling water inlet B1 and circulating cooling water outlet B2.

[0022] The permeate condenser 9 is connected to the permeate storage tank 10. The permeate storage tank 10 is connected to the permeate vaporization membrane vacuum pump 11 and the permeate discharge pump 12. The permeate storage tank 10 is used to store permeate water, and the permeate discharge pump 12 is used to pump out the permeate water.

[0023] Specifically, the series pervaporation membrane module 8 includes several membrane modules connected in series. Each membrane module's pervaporation membrane includes a support and a separation layer coated on the surface of the support. The support is a porous ceramic tube with a pore size of 0.1-1 μm, and the separation layer is a silicon oxide or zirconium oxide separation layer with a thickness of 200-500 nm.

[0024] In the specific operation of this device, the acidic wastewater discharged from the molding process is input into a vacuum evaporator 1. The vacuum degree is controlled at -0.085~-0.095 MPa, and the temperature is 50-70℃. The acid and water are evaporated, while impurities such as salts and macromolecular organic matter remain in the residual liquid of the evaporator. After evaporation, a crude acid solution with a concentration of 13-30% is obtained, with an acid recovery rate of over 80% and a removal rate of ≥95% for impurities such as salts and colloids in the waste liquid. The association between acetic acid and water increases the boiling point of the mixture, which is 118℃ at normal pressure and drops to 59℃ when the pressure is reduced to -0.09 MPa. Salts (such as ammonium acetate, calcium acetate, magnesium acetate, etc.), colloids, and macromolecular organic matter (proteins, lipids) in the waste acid solution remain in the evaporation residual liquid due to their high boiling points and low vapor pressures.

[0025] The evaporated crude acid solution is stored in the evaporation liquid storage tank 3. The crude acid solution is pumped into the series pervaporation membrane module 8 through the evaporation liquid transfer pump 5. Selective dehydration is carried out under the conditions of operating temperature 50-80℃ and transmembrane pressure difference 0.1-0.5MPa (vacuum degree maintained on the downstream side of the membrane -0.09~-0.1 MPa). Concentration polarization is prevented by adjusting the membrane surface flow rate 0.8-1.2m / s. Finally, a recovered acid with a concentration ≥60% is produced, and the acetic acid recovery rate is ≥99.9%.

[0026] The pervaporation membrane uses a porous ceramic tube as a support (pore size 0.1-1μm) and is coated with a silica (SiO2) or zirconium oxide (ZrO2) separation layer (thickness 200-500 nm) to form an asymmetric composite membrane (pore size 0.3-0.45nm). Water is preferentially adsorbed and passes through the membrane pores due to its high polarity and small molecular size, while formic acid / acetic acid molecules are retained due to their hydrophobic interaction with the membrane material.

[0027] Finally, the concentrated acid product (60% or higher) is mixed with new acid at a mass ratio of 1:0.3 to 1:2, and the mixture is adjusted to the concentration required for the coagulation process for latex coagulation.

[0028] When the device of this utility model is specifically applied Application Example 1: Acidic wastewater discharged from the molding process of a latex filament factory was analyzed. The composition was: acetic acid concentration 28%, COD value 410,000 mg / L, containing 1.2% ammonium acetate, 0.3% calcium acetate, and 0.3% colloidal particles. The acidic wastewater was pumped into a vacuum evaporator 1, with the vacuum level controlled at -0.09 MPa and the temperature at 60℃. After evaporation, the crude acid concentration was 26%, the acetic acid recovery rate was 78%, and the ammonia nitrogen concentration decreased to 1.6 mg / L. The crude acid was then pumped into a three-stage series-connected pervaporation membrane module 8 (SiO2 membrane, composite membrane pore size 0.35 nm), with an operating temperature of 65℃ and a downstream vacuum level of -0.095 MPa. Finally, acetic acid with a concentration of 62% was obtained, with a recovery rate of 99.94%. The recovered acid was mixed with fresh acid at a 1:1 ratio and used for latex coagulation.

[0029] Application Example 2: Acetic acid wastewater from a certain production area was treated. The composition was analyzed as follows: acetic acid concentration 18%, COD value 310,000 mg / L, containing 2.3% ammonium acetate and 0.5% lipids. The acidic wastewater was pumped into a vacuum evaporator 1, and evaporation was carried out at a vacuum of -0.085 MPa and a temperature of 68℃. After evaporation, the crude acid concentration was 17%, the acetic acid recovery rate was 81%, and the ammonia nitrogen concentration decreased to 2.1 mg / L. The crude acid solution was then pumped into a two-stage series-connected pervaporation membrane module 8 (SiO2 membrane, composite membrane pore size 0.4 nm), operating at 80℃ and a downstream vacuum of -0.092 MPa, ultimately producing acetic acid with a concentration of 65% and a recovery rate of 99.92%. The recovered acid was mixed with virgin acid at a ratio of 1:0.5 and used for latex coagulation.

[0030] Application Example 3: For acetic acid waste liquid (acetic acid concentration 24%, COD value 380,000 mg / L, containing 1.6% ammonium salt and 0.4% protein), the acidic waste liquid was pumped into a vacuum evaporator 1, with a vacuum level of -0.095 MPa and a temperature of 50℃, to simultaneously evaporate acetic acid and water. The resulting crude acid solution had a concentration of 22%, an overall acid recovery rate of 85%, and the ammonia nitrogen concentration decreased to 1.2 mg / L. The crude acid solution was then pumped into a four-stage series-connected pervaporation membrane module 8 (SiO2 membrane, composite membrane pore size 0.3 nm), with an operating temperature of 75℃ and a downstream vacuum level of -0.094 MPa. The final acid concentration obtained was 68%, with a recovery rate of 99.95%. The recovered acid was replenished with fresh acid at a ratio of 1:1.2 for latex coagulation.

[0031] Of course, the above embodiments are only for illustrating the technical concept and features of this utility model, and their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be used to limit the protection scope of this utility model. All modifications made in accordance with the spirit and essence of the main technical solution of this utility model should be covered within the protection scope of this utility model.

Claims

1. A device for recovering waste acid from the molding waste liquid of a latex filament production line, characterized in that: The system includes a vacuum evaporator (1), the top of which is connected to an evaporator liquid condenser (2), the evaporator liquid condenser (2) is connected to an evaporator liquid storage tank (3), the evaporator liquid storage tank (3) is connected to an evaporator vacuum pump (4) and an evaporator liquid transfer pump (5), the evaporator liquid transfer pump (5) is connected to a heat exchanger (6), the heat exchanger (6) is connected to a heater (7), the heater (7) is connected to a series pervaporation membrane assembly (8), the concentrate outlet of the series pervaporation membrane assembly (8) is connected to the heat exchanger (6), the permeate outlet of the series pervaporation membrane assembly (8) is connected to a permeate liquid condenser (9), the permeate liquid condenser (9) is connected to a permeate liquid storage tank (10), and the permeate liquid storage tank (10) is connected to a pervaporation membrane vacuum pump (11) and a permeate liquid discharge pump (12).

2. The device for recovering waste acid from the molding waste liquid of a latex filament production line according to claim 1, characterized in that: The vacuum evaporator (1) has a waste acid inlet (1a) on one side, a vacuum evaporator steam outlet (1b) at the top and a vacuum evaporator concentrate outlet (1c) at the bottom. The vacuum evaporator steam outlet (1b) is connected to the evaporator condenser (2). The vacuum evaporator (1) is equipped with a heating tube (1d).

3. The device for recovering waste acid from the molding waste liquid of a latex filament production line according to claim 1, characterized in that: Both the evaporator condenser (2) and the permeate condenser (9) are provided with a circulating cooling water inlet (B1) and a circulating cooling water outlet (B2).

4. The device for recovering waste acid from the molding waste liquid of a latex filament production line according to claim 2, characterized in that: Both the heating tube (1d) and the heater (7) are provided with a steam inlet (A1) and a steam condensate outlet (A2).

5. The device for recovering waste acid from the molding waste liquid of a latex filament production line according to claim 1, characterized in that: The series pervaporation membrane assembly (8) includes a plurality of membrane assemblies connected in series, and the pervaporation membrane of each membrane assembly includes a support and a separation layer coated on the surface of the support.

6. The device for recovering waste acid from the molding waste liquid of a latex filament production line according to claim 5, characterized in that: The support is a porous ceramic tube, and the separation layer is a silicon oxide or zirconium oxide separation layer.

7. The device for recovering waste acid from molding waste liquid in a latex filament production line according to claim 6, characterized in that: The porous ceramic tube has a pore size of 0.1-1 μm, and the separation layer has a thickness of 200-500 nm.

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