System and method for treating polymer forming wash water

Abstract

The present application relates to the technical field of polymer forming water washing liquid treatment, in particular to a system and method for treating polymer forming water washing liquid, the method for treating polymer forming water washing liquid comprising: settling the polymer forming water washing liquid, filtering the obtained sedimentation flow after passing through a pulse type diaphragm pump to obtain pure polymer forming water washing liquid and polymer residue; recycling the pure polymer forming water washing liquid; collecting the polymer residue; the flow rate of the sedimentation flow being 3-30 t / h; the pulse cycle of the pulse type diaphragm pump being 3-30 s. The method can efficiently remove the polymer residue in the polymer forming water washing liquid, the polymer content in the pure polymer forming water washing liquid after residue removal is significantly reduced, and waste emission is reduced.

Description

Technical Field

[0001] This invention relates to the field of polymer molding washing liquid treatment technology, and specifically to a system and method for treating polymer molding washing liquid. Background Technology

[0002] In chemical production processes, especially those involving polymer materials such as ethylene-vinyl alcohol copolymer (EVOH), the reaction of raw materials and the separation of products often result in the formation of large amounts of insoluble solid impurities, such as coke, salt precipitates, unreacted raw material particles, and material residues that cannot be separated later. Traditional slag removal methods mostly employ physical methods, such as filtration and sedimentation. These methods often overlook the impact of differences in the physical properties of materials on slag removal efficiency, leading to low slag removal efficiency and long processing times. Long-term reliance on physical methods for slag removal may also exacerbate equipment wear, increase maintenance costs, affect production continuity and the final purity of the product, and these methods are difficult to recycle effectively during the process, potentially causing environmental problems.

[0003] The EVOH molding washing solution contains a large amount of solid EVOH residue, as well as a small amount of EVOH that dissolves in the washing solution at high temperatures. This EVOH residue accumulates in the washing solution storage tank over a long period. When the washing solution is sent to the downstream treatment system, it can cause increased vibration of the pump bearings, increased machine temperature, fluctuations in downstream feed flow, and fluctuations in the process parameters of the downstream treatment system. Furthermore, regularly entering the washing solution tank to remove the EVOH residue poses safety hazards and raises environmental compliance issues.

[0004] Therefore, developing an efficient, environmentally friendly, and long-term stable extraction and removal system for polymer residues has become an urgent need in the current chemical industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low efficiency, long processing time, and poor environmental performance of existing methods for removing polymer residues from washing solutions, and to provide a method and system for treating polymer molding washing solutions. This method efficiently removes polymer residues from the washing solution, achieving effective separation of the residues, reducing waste emissions, optimizing resource utilization, significantly extending pump operating time, and increasing the process stability of post-treatment processes for polymer molding washing solutions.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for treating a polymer molding washing solution, the method comprising:

[0007] The polymer molding washing solution is settled, and the settled material is filtered after passing through a pulse diaphragm pump to obtain pure polymer molding washing solution and polymer residue; the pure polymer molding washing solution is recycled; and the polymer residue is collected.

[0008] The flow rate of the sedimentation material is 3-30 t / h; the pulse cycle of the pulse diaphragm pump is 3-30 s.

[0009] A second aspect of the present invention provides a system for treating polymer molding washing liquid, comprising: a sedimentation unit, a filtration unit, and a pulse-type diaphragm pump unit;

[0010] The settling unit is used to settle the polymer molding washing liquid;

[0011] The filtration unit is used to filter the sedimentation stream obtained by sedimentation to obtain pure polymer molding washing liquid and polymer residue.

[0012] The pulse-type diaphragm pump unit is used to pump the sedimented material obtained from sedimentation into the filtration unit.

[0013] Through the above technical solution, the present invention has the following beneficial effects:

[0014] The method for treating polymer molding washing liquid provided by this invention employs a pulse-type diaphragm pump. The settled material obtained from sedimentation is filtered after passing through the pulse-type diaphragm pump. The flow rate of the settled material is controlled within a specific range. The pulse-type diaphragm pump applies flow and pressure pulses at specific pulse cycles, thereby effectively stripping away the solid residue accumulated on the filter screen and allowing it to leave the filter screen surface with the liquid flow. This maintains filtration efficiency and efficiently removes polymer solid residue from the polymer molding washing liquid. After residue removal, the polymer content in the pure polymer molding washing liquid is significantly reduced, greatly extending the operating time and increasing the process stability of the post-treatment process of the pure polymer molding washing liquid. Furthermore, the filtered polymer residue is effectively treated, reducing waste emissions. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0016] Figure 1 This is a process flow diagram of the polymer molding washing liquid described in this invention.

[0017] Explanation of reference numerals in the attached figures

[0018] 1. Polymer residue settling tank; 2. Pulse diaphragm pump; 3. Filter

[0019] 4. Polymer molding washing liquid discharge tank; 5. Submersible pump Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] The first aspect of the present invention provides a method for treating a polymer molding washing solution, the method comprising:

[0022] The polymer molding washing solution is settled, and the settled material is filtered after passing through a pulse diaphragm pump to obtain pure polymer molding washing solution and polymer residue; the pure polymer molding washing solution is recycled; and the polymer residue is collected.

[0023] The flow rate of the sedimentation material is 3-30 t / h; the pulse cycle of the pulse diaphragm pump is 3-30 s.

[0024] In this invention, the inventors unexpectedly discovered that filtering the sedimented material stream obtained from sedimentation using a pulse-type diaphragm pump, and controlling the flow rate of this sedimented material stream within a specific range, with the pulse-type diaphragm pump applying flow-pressure pulses at specific pulse cycles, effectively strips away accumulated solid residues on the filter screen and allows them to leave the filter screen surface with the liquid flow, maintaining filtration efficiency while efficiently removing polymer solid residues from the polymer molding washing solution. After residue removal, the polymer content in the pure polymer molding washing solution is significantly reduced, increasing the process stability of the subsequent processing steps for the pure polymer molding washing solution. Furthermore, the filtered polymer residues are effectively treated, reducing waste emissions. Preferably, this facilitates a more stable discharge flow rate from the subsequent submersible pump, a significant decrease and stabilization in the operating temperature of the submersible pump windings, and a significant decrease and stabilization in the vibration value of the submersible pump bearings, greatly extending the submersible pump's operating time.

[0025] In this invention, unless otherwise specified, the polymer molding washing solution refers to the molding washing solution obtained by washing copolymer particles obtained after extrusion molding of a polymer solution in existing polymer preparation methods. In this invention, the type of polymer used in the method for treating the polymer molding washing solution is not particularly limited; it can be any polymer known in the art that requires washing, and is particularly suitable for treating ethylene-vinyl alcohol copolymer (EVOH) molding washing solutions.

[0026] In this invention, controlling the flow rate of the settling material within the aforementioned range is beneficial for efficiently removing polymer solid residues from the settling material, resulting in better slag removal. It also enhances the impact and vibration effects generated by the pulse diaphragm pump, making it easier for impurities on the filter screen to be peeled off and leave the filter screen surface with the liquid flow, thus maintaining filtration efficiency. When the flow rate of the settling material is higher than 30 t / h, the polymer solid residues cannot be fully removed before contacting the filter screen, affecting the slag removal effect. When the flow rate of the settling material is less than 3 t / h, the polymer solid residues are more likely to deposit on the filter screen surface, increasing filtration resistance and slowing down the processing speed.

[0027] In some embodiments of the present invention, preferably, the flow rate of the settling material is 3-25 t / h, for example, it can be 3 t / h, 4 t / h, 6 t / h, 8 t / h, 10 t / h, 12 t / h, 14 t / h, 15 t / h, 17 t / h, 19 t / h, 21 t / h, 23 t / h, 25 t / h, and any value within the range of the two values ​​above.

[0028] In this invention, controlling the pulse cycle of the pulse-type diaphragm pump within the above-mentioned range is beneficial for effectively removing polymer residues accumulated on the filter screen, preventing filter screen blockage, and promoting effective contact between suspended matter in the sedimentation flow and the filter screen, thereby improving filtration efficiency and reducing energy consumption.

[0029] In some embodiments of the present invention, preferably, the pulse period of the pulse-type diaphragm pump is 3-15s, for example, it can be 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, and any value within the range of the two values ​​above.

[0030] In some embodiments of the present invention, preferably, the flow ratio of the polymer molding washing liquid to the sedimentation material flow is 1:0.55-1, for example, it can be 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, and any value within the range of the two values ​​above.

[0031] In this invention, controlling the flow ratio of polymer molding washing liquid to sedimentation material within the above-mentioned range is beneficial for the polymer residue to settle, thus initially removing polymer solid residue from the polymer molding washing liquid and achieving a better slag removal effect.

[0032] Preferably, the flow ratio of the polymer molding washing liquid to the sedimentation material flow is 1:0.6-1.

[0033] In some embodiments of the present invention, preferably, the temperature of the polymer molding washing solution is 35-65°C, for example, it can be 35°C, 40°C, 45°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 60°C, 65°C, or any value within the range of the two values ​​above.

[0034] In this invention, the temperature of the polymer molding washing solution is controlled within the above-mentioned range, which reduces the amount of polymer residue dissolved in the polymer molding washing solution. This is beneficial for effectively removing polymer solid residue from the polymer washing solution, thereby significantly reducing the polymer content in the pure polymer molding washing solution obtained after residue removal.

[0035] Preferably, the temperature of the polymer molding washing solution is 35-60°C, more preferably 45-55°C, and even more preferably 45-50°C.

[0036] In some embodiments of the present invention, preferably, the mass ratio of the polymer in the polymer molding washing solution to the polymer in the pure polymer molding washing solution is 1:0.01-0.35, for example, it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.07, 1:0.08, 1:0.09, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, and any value within the range of the two values ​​above.

[0037] In this invention, the polymer content in the pure polymer molding washing solution is reduced compared to the polymer content in the polymer molding washing solution, which helps to extend the running time of the submersible pump and increase the process stability of the post-treatment process of the pure polymer molding washing solution.

[0038] Preferably, the mass ratio of polymer in the polymer molding washing solution to polymer in the pure polymer molding washing solution is 1:0.01-0.15.

[0039] In this invention, unless otherwise specified, the mass ratio of polymer in the polymer molding washing solution to polymer in the pure polymer molding washing solution is = (polymer content in the polymer molding washing solution × polymer molding washing solution flow rate) / (polymer content in the pure polymer washing solution / initial pure polymer washing solution flow rate). The initial pure polymer washing solution flow rate refers to the flow rate of the pure polymer washing solution obtained for the first time after filtration. The polymer content in the polymer molding washing solution and the polymer content in the pure polymer molding washing solution of this invention are tested using a solids content analyzer.

[0040] In this invention, the recycling method is not particularly limited, and conventional polymer washing liquid recycling methods used in the art can be employed. Preferably, the recycling method includes: pumping the pure polymer molding washing liquid into a distillation system for recycling using a submersible pump.

[0041] In some embodiments of the present invention, preferably, the ratio of the initial discharge flow rate of the submersible pump to the flow rate of the settling material is 0.3-6:1, for example, it can be 0.3:1, 0.4:1, 0.5:1, 0.55:1, 0.6:1, 0.7:1, 0.75:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 5:1, 6:1, and any value within the range of the two values ​​above.

[0042] In this invention, controlling the ratio of the initial output flow rate of the submersible pump to the flow rate of the sedimentation stream within the above-mentioned range helps to ensure that the sedimentation stream has sufficient residence time during the filtration process, allowing the polymer residue to fully contact the filter screen and be intercepted, thereby improving the filtration effect.

[0043] Preferably, the ratio of the initial discharge flow rate of the submersible pump to the flow rate of the sedimentation material is 0.5-3.5:1.

[0044] In this invention, unless otherwise specified, the initial delivery flow rate of the submersible pump refers to the flow rate of the pure polymer molding washing liquid initially delivered from the pump outlet after the submersible pump starts to operate stably; the final delivery flow rate of the submersible pump refers to the flow rate of the pure polymer molding washing liquid delivered from the pump outlet before the pump stops operating.

[0045] In some embodiments of the present invention, preferably, the ratio of the final delivery flow rate of the submersible pump to the initial delivery flow rate of the submersible pump is 0.5-1:1, for example, it can be 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, and any value within the range of the two values ​​mentioned above.

[0046] In this invention, the final discharge flow rate of the submersible pump reflects the stability of the pump's flow output after long-term operation. Controlling the ratio of the final discharge flow rate of the submersible pump to the initial discharge flow rate of the submersible pump within the above-mentioned range helps to ensure the stability of the entire process, maintain filtration efficiency, reduce the polymer content in the pure polymer molding washing solution, and improve production efficiency.

[0047] Preferably, the ratio of the final discharge flow rate of the submersible pump to the initial discharge flow rate of the submersible pump is 0.55-0.95:1.

[0048] In this invention, the mesh size of the filter screen is not particularly limited, and can be adjusted according to the material characteristics and the size of the polymer solid residue. Preferably, the mesh size of the filter screen is 100-300 mesh, and more preferably 120-180 mesh.

[0049] In this invention, controlling the mesh size of the filter screen within the above-mentioned range is beneficial to improving filtration efficiency while ensuring filtration effect.

[0050] In some embodiments of the present invention, preferably, the polymer residue is collected periodically, with a collection cycle of 3-7 days relative to the polymer molding washing solution with a polymer concentration of 0.1-10 wt%.

[0051] In this invention, the collection cycle of polymer residue is controlled within the above-mentioned range relative to the polymer molding washing liquid concentration, so as to avoid clogging the filter screen and affecting the filtration accuracy, reduce waste discharge, and optimize resource utilization.

[0052] A second aspect of the present invention provides a system for treating polymer molding washing liquid, comprising: a sedimentation unit, a filtration unit, and a pulse-type diaphragm pump unit;

[0053] The settling unit is used to settle the polymer molding washing liquid;

[0054] The filtration unit is used to filter the sedimentation stream obtained by sedimentation to obtain pure polymer molding washing liquid and polymer residue.

[0055] The pulse-type diaphragm pump unit is used to pump the sedimented material obtained from sedimentation into the filtration unit.

[0056] In this invention, the system for treating polymer molding washing liquid includes a sedimentation unit, a filtration unit, and a pulse-type diaphragm single pump unit, which efficiently removes polymer residues from the polymer molding washing liquid, achieves effective separation of polymer residues, reduces waste emissions, optimizes resource utilization, greatly extends the operating time of the pump, and increases the process stability of the post-treatment process of polymer molding washing liquid.

[0057] In this invention, unless otherwise specified, the polymer molding washing liquid comes from the polymer molding system, which refers to the polymer molding washing liquid obtained by washing the polymer copolymer particles obtained after the polymer solution is extruded and molded in the molding system.

[0058] In this invention, the settling unit can be any device conventionally used in the art for settling polymer molding washing liquid, preferably a polymer residue settling tank. The liquid level in the polymer residue settling tank is not particularly limited in this invention, and those skilled in the art can choose according to actual needs. Preferably, in this invention, the polymer residue settling tank is equipped with a heating device.

[0059] In this invention, the filtration unit can be any solid-liquid separation device conventionally used in the art for filtering polymer molding washing liquids, preferably a quick-release frame filter. The quick-release frame filter of this invention allows for easy and quick disassembly and replacement of the filter screen.

[0060] In this invention, preferably, the pulse-type diaphragm pump unit is a pulse-type diaphragm pump. In this invention, the periodic pulse force generated by the pulse-type diaphragm pump with a specific cycle is beneficial for generating impact force during the delivery of polymer molding washing liquid, thereby facilitating the effective stripping of solid residues accumulated on the filter screen of the filter unit and allowing them to leave the filter screen surface with the liquid flow, reducing the risk of deposition and clogging.

[0061] In some embodiments of the present invention, preferably, the filtration unit further includes a separation module for detecting the polymer content in the sedimentation stream and adjusting the cycle of separating polymer residues.

[0062] In some embodiments of the present invention, preferably, the system further includes a recycling unit, which includes a polymer molding washing liquid discharge tank and a submersible pump.

[0063] In some embodiments of the present invention, preferably, the polymer molding washing liquid discharge tank is used to discharge pure polymer molding washing liquid.

[0064] In some embodiments of the present invention, preferably, the submersible pump is used to pump the pure polymer molding washing liquid into a distillation system for recycling.

[0065] In some embodiments of the present invention, preferably, the outlet of the filtration unit is connected to the inlet of the polymer molding washing liquid discharge tank, and the outlet of the polymer molding washing liquid discharge tank is connected to the inlet of the submersible pump.

[0066] The following combination Figure 1 The method and system of the present invention will be described below, including preferred embodiments:

[0067] The polymer molding washing liquid containing polymer residue from the polymer molding system is fed into a polymer residue settling tank 1 for settling. The polymer residue initially accumulates at the bottom of the settling tank 1, resulting in a settling stream. The temperature of the polymer molding washing liquid is 35-65℃, the flow rate of the settling stream is 3-30 t / h, and the flow ratio of the polymer molding washing liquid to the settling stream is 1:0.55-1. The settling stream is then pumped into a filter 3 by a pulse diaphragm pump 2, where the pulse period of the pulse diaphragm pump 2 is 3-30 s, yielding a pure polymer molding washing liquid and polymer residue. The mass ratio of polymer in the polymer molding washing liquid to the polymer in the pure polymer molding washing liquid is 1:0.01-0.35. The polymer residue is periodically separated and subjected to safe and environmentally friendly treatment. The resulting pure polymer molding washing liquid is then fed into a polymer molding washing liquid discharge tank 4 and pumped into a washing liquid distillation system by a submersible pump 5 for further processing, which facilitates the recovery and reuse of beneficial components.

[0068] The present invention will be described in detail below through embodiments.

[0069] In the following examples and comparative examples, the content of EVOH in the EVOH molding washing solution and the content of EVOH in the pure EVOH molding washing solution were tested using a solid content analyzer.

[0070] In the following examples and comparative examples, the mass ratio of EVOH in the washing solution to EVOH in the pure washing solution is: (EVOH content in the EVOH forming washing solution × EVOH forming washing solution flow rate) / (EVOH content in the pure EVOH washing solution / initial pure EVOH washing solution flow rate).

[0071] Example 1

[0072] The EVOH molding washing liquid (EVOH content 10wt%) containing EVOH residue from the molding system is introduced into the EVOH residue settling tank for sedimentation. The liquid level in the EVOH residue settling tank is controlled at 50%. The EVOH residue initially accumulates at the bottom of the EVOH residue settling tank. The resulting sediment stream is pumped into a filter by a pulse diaphragm pump for filtration. The filter screen has a mesh size of 100 mesh, resulting in pure EVOH molding washing liquid and EVOH residue. The EVOH residue is separated every 5 days and subjected to safe and environmentally friendly treatment. The resulting pure EVOH molding washing liquid is then introduced into the EVOH molding washing liquid discharge tank. The liquid level in the EVOH residue settling tank is controlled at 50%. The liquid is then pumped into the washing liquid distillation system by a submersible pump for further processing, which facilitates the recovery and reuse of components.

[0073] Example 2-17

[0074] Examples 2-17 used the same method as Example 1 to treat the EVOH molding washing solution, except that the reaction was carried out under the conditions shown in Table 1.

[0075] Comparative Examples 1-2

[0076] The method described in Example 1 is different except that the reaction is carried out under the conditions shown in Table 1.

[0077] Table 1

[0078]

[0079] Table 1 (continued)

[0080]

[0081]

[0082] As shown in Table 1, the method for treating EVOH molding washing liquid provided by this invention achieves a sedimentation flow rate of 3-25 t / h and a pulse cycle of 3-30 s. The mass ratio of EVOH in the EVOH molding washing liquid to the EVOH in the obtained pure EVOH molding washing liquid is 1:0.01-0.35. The content of EVOH residue separated every 5 days is 2.5-6 kg. This method effectively removes EVOH residue from the EVOH molding washing liquid, achieves effective separation of EVOH residue, extends the operating time of the submersible pump, and increases the process stability of the EVOH molding washing liquid post-treatment process.

[0083] Based on the embodiments, comparative examples, and Table 1, it can be seen that, compared with the embodiments, the flow rate of the sedimentation material in Comparative Example 1 is not within the range defined by the present invention, and the flow rate of the sedimentation material in Comparative Example 2 is not within the range provided by the present invention, and the temperature of the EVOH molding washing liquid is not within the preferred range provided by the present invention, resulting in a higher EVOH residue content in the EVOH molding washing liquid.

[0084] Test Example 1

[0085] The vibration values ​​of the submersible pump bearings of the pure EVOH molding washing solution obtained in Example 1 and the pure EVOH molding washing solution obtained in Comparative Example 1 were tested, and the test results are shown in Table 2.

[0086] Table 2

[0087]

[0088] As can be seen from the results in Table 2, the purified EVOH molding washing liquid obtained by the method provided by this invention has a lower and more stable vibration value of the submersible pump bearing, with a maximum fluctuation deviation of only 0.2 mm / s, which is 87.5% lower than that of Comparative Example 1. The EVOH molding washing liquid obtained in Comparative Example 1 has a high EVOH residue content, which easily clogs the inlet of the submersible pump, causing the pump to jam. The vibration value of the submersible pump bearing is greater than the safe range (0-1.8 mm / s) and fluctuates greatly, with a maximum fluctuation deviation of up to 1.6 mm / s.

[0089] Test Example 2

[0090] The operating temperature of the submersible pump windings of the pure EVOH molding washing solution obtained in Example 1 and the pure EVOH molding washing solution obtained in Comparative Example 1 were tested, and the test results are shown in Table 3.

[0091] Table 3

[0092]

[0093] As can be seen from the results in Table 3, the purified EVOH molding washing liquid obtained by the method of the present invention has a lower submersible pump winding temperature, reaching a maximum of 56.82℃, which is 23.61% lower than that of Comparative Example 1. The EVOH molding washing liquid obtained in Comparative Example 1 has a high EVOH residue content, which easily clogs the inlet of the submersible pump. The pump operates under high load and high temperature for a long time, and the submersible pump winding temperature is higher than the design operating temperature of the pump by 55℃, and fluctuates greatly, reaching a maximum of 74.38℃, with a fluctuation deviation of 13.7%.

[0094] Test Example 3

[0095] The discharge flow rates of the pure EVOH molding washing solution obtained in Example 1 and the pure EVOH molding washing solution obtained in Comparative Example 1 were tested by a submersible pump. The test results are shown in Table 4.

[0096] Table 4

[0097]

[0098] As can be seen from the results in Table 4, the purified EVOH molding washing liquid obtained by the method of the present invention has a basically stable discharge flow rate of 14-15 t / h from the submersible pump. The EVOH molding washing liquid obtained in Comparative Example 1 has a high EVOH residue content, which easily clogs the inlet of the submersible pump, resulting in poor submersible pump delivery and large fluctuations in the discharge flow rate of the submersible pump, ranging from a minimum of 6.54 t / h to a maximum of 25.68 t / h, with a fluctuation deviation of 19.14 t / h.

[0099] Test Example 4

[0100] The EVOH content in the pure EVOH molding washing solution obtained in Example 1 and the pure EVOH molding washing solution obtained in Comparative Example 1 was tested, and the test results are shown in Table 5.

[0101] Table 5

[0102]

[0103] As can be seen from the results in Table 5, the EVOH molding washing solution obtained by the method of the present invention is effectively purified, with the EVOH content not exceeding 0.6 wt%, which is beneficial to the process stability of the post-treatment process and significantly improves the recycling effect of the EVOH molding washing solution. In contrast, the EVOH content in the EVOH molding washing solution obtained in Comparative Example 1 is too high, with a maximum of 8.7 wt% and a minimum of 4.3 wt%, which can easily lead to damage to the submersible pump and fluctuations in the process parameters of the post-treatment process of the washing solution.

[0104] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for treating polymer molding washing liquid, characterized in that, The method includes: The polymer molding washing solution is settled, and the settled material is filtered after passing through a pulse diaphragm pump to obtain pure polymer molding washing solution and polymer residue; the pure polymer molding washing solution is recycled; and the polymer residue is collected. The flow rate of the sedimentation material is 3-30 t / h; the pulse cycle of the pulse diaphragm pump is 3-30 s.

2. The method according to claim 1, wherein, The flow rate of the settled material is 3-25 t / h; Preferably, the pulse period of the pulse-type diaphragm pump is 3-15s.

3. The method according to claim 1 or 2, wherein, The temperature of the polymer molding washing solution is 35-65℃, preferably 35-60℃, and more preferably 45-55℃.

4. The method according to claim 1 or 2, wherein, The flow ratio of the polymer molding washing liquid to the sedimentation material is 1:0.55-1, preferably 1:0.6-1.

5. The method according to claim 1 or 2, wherein, The mass ratio of polymer in the polymer molding washing solution to polymer in the pure polymer molding washing solution is 1:0.01-0.35, preferably 1:0.01-0.

15.

6. The method according to claim 1 or 2, wherein, The recycling method includes: pumping the pure polymer molding washing liquid into a distillation system for recycling by submersible pump; Preferably, the ratio of the initial discharge flow rate of the submersible pump to the flow rate of the settled material is 0.3-6:1, more preferably 0.5-3.5:1; Preferably, the ratio of the final discharge flow rate of the submersible pump to the initial discharge flow rate of the submersible pump is 0.5-1:1, and more preferably 0.55-0.95:

1.

7. The method according to claim 1 or 2, wherein, The filter screen used for filtration has a mesh size of 100-300, preferably 120-180.

8. The method according to claim 1 or 2, wherein, The polymer residue is collected periodically, with a collection cycle of 3-7 days relative to the polymer molding washing solution with a polymer concentration of 0.1-10 wt%.

9. A system for treating polymer molding washing liquid, characterized in that, include: Settling unit, filtration unit, and pulse-type diaphragm pump unit; The settling unit is used to settle the polymer molding washing liquid; The filtration unit is used to filter the sedimentation stream obtained by sedimentation to obtain pure polymer molding washing liquid and polymer residue. The pulse-type diaphragm pump unit is used to pump the sedimented material obtained from sedimentation into the filtration unit.

10. The system according to claim 9, wherein, The filtration unit also includes a separation module for detecting the polymer content in the sedimentation stream and adjusting the cycle for separating polymer residues. Preferably, the system further includes a recycling unit, which includes a polymer molding washing liquid discharge tank and a submersible pump; Preferably, the polymer molding washing liquid discharge tank is used to discharge pure polymer molding washing liquid; Preferably, the submersible pump is used to pump the pure polymer molding washing liquid into the distillation system for recycling; Preferably, the outlet of the filtration unit is connected to the inlet of the polymer molding washing liquid discharge tank, and the outlet of the polymer molding washing liquid discharge tank is connected to the inlet of the submersible pump.

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