Device and method for improving chroma removal rate of NMMO (N-methylmorpholine-N-oxide) solvent

Abstract

The invention provides a method for improving the chromaticity removal rate of an NMMO solvent, which comprises the following steps: carrying out adsorption treatment on an NMMO solvent recovery solution by adopting anion exchange resin, and adjusting one or more of conductivity, temperature, flow, chromaticity and turbidity of the NMMO solvent recovery solution according to a formula (1), so that the P value is greater than or equal to 0.9412. The invention also provides a device for improving the chroma removal rate of the NMMO solvent. When the anion exchange resin is adopted to perform adsorption treatment on the NMMO solvent recovery liquid, one or more of the conductivity, the temperature, the flow, the chromaticity and the turbidity of the NMMO solvent recovery liquid are adjusted according to the formula (1), so that when the P value is larger than or equal to 0.9412, the removal rate of the anion exchange resin on the chromaticity of the NMMO solvent recovery liquid can be increased and reaches 50% or above.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, and in particular to a device and method for improving the chroma removal rate of NMMO solvent. Background Art

[0002] An aqueous solution of N-methylmorpholine-N-oxide (NMMO) is an excellent solvent for cellulose and is widely used in cellulose fiber production. Lyocell fiber is a regenerated cellulose fiber made by wet and dry spinning of cellulose dissolved in NMMO.

[0003] During the preparation of Lyocell fibers, the NMMO solvent undergoes various reactions in a high-temperature production environment, producing a large amount of colored substances, which increases the chromaticity of the NMMO aqueous solution and affects the whiteness of the fiber. Summary of the Invention

[0004] In view of this, the present invention provides a device and method for improving the chroma removal rate of NMMO solvent. The method provided in this application can adjust the processing parameters in real time to maintain a high chroma removal rate of NMMO solvent.

[0005] The present application provides a method for improving the chroma removal rate of NMMO solvent, comprising:

[0006] The NMMO solvent recovery liquid is subjected to adsorption treatment using an anion exchange resin, and one or more of the conductivity, temperature, flow rate, color, and turbidity of the NMMO solvent recovery liquid is adjusted according to formula (1) so that the P value is greater than or equal to 0.9412:

[0007]

[0008] In formula (1), G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0009] In some specific implementations, the anion exchange resin is D201 strongly basic macroporous anion exchange resin.

[0010] In some specific implementations, the NMMO solvent recovery solution is obtained according to the following method:

[0011] The NMMO solution in the spinning coagulation bath is coagulated and then filtered to obtain an NMMO solvent recovery liquid.

[0012] In some specific implementations, the method further includes: using a cation exchange resin to adsorb the NMMO solvent recovery liquid treated with the anion exchange resin.

[0013] In some specific implementations, the temperature of the NMMO solvent recovery liquid is 20° C. to 30° C.;

[0014] The conductivity of the NMMO solvent recovery liquid is 55 μs / cm to 75 μs / cm;

[0015] The flow rate of the NMMO solvent recovery liquid is 30m 3 / h~40m 3 / h.

[0016] The present application also provides a device for improving the chroma removal rate of NMMO solvent, comprising:

[0017] Anion exchange resin adsorption unit;

[0018] Conductivity sensor, temperature sensor, flow sensor, colorimetry sensor and turbidity sensor respectively arranged at the liquid inlet of the anion exchange resin adsorption unit;

[0019] an adjustment unit, the adjustment unit including at least one of a flow adjustment unit for adjusting the flow rate of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a temperature adjustment unit for adjusting the temperature of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a turbidity adjustment unit for adjusting the turbidity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a chromaticity adjustment unit for adjusting the chromaticity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, and a conductivity adjustment unit for adjusting the conductivity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit;

[0020] a control unit, the control unit receiving conductivity data from the conductivity sensor, temperature data from the temperature sensor, flow data from the flow sensor, colorimetry data from the colorimetry sensor, and turbidity data from the turbidity sensor, integrating the data according to formula (1) to obtain a P value, obtaining at least one of a temperature adjustment signal, a colorimetry adjustment signal, a turbidity adjustment signal, a conductivity adjustment signal, and a flow adjustment signal based on the P value, and sending the adjustment signal to a corresponding adjustment device;

[0021]

[0022] In formula (1), P ≥ 0.9412, G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0023] In some specific implementations, the method further includes: a coagulation unit whose liquid outlet is connected to the liquid inlet of the anion exchange resin adsorption unit.

[0024] In some specific implementations, a filtration unit is further included between the coagulation unit and the anion exchange resin adsorption unit.

[0025] In some specific implementations, the method further includes: a cation exchange resin adsorption unit whose liquid inlet is connected to the liquid outlet of the anion exchange resin adsorption unit.

[0026] In some specific implementations, the anion exchange resin is D201 strongly basic macroporous anion exchange resin.

[0027] When the present application uses an anion exchange resin to perform adsorption treatment on the NMMO solvent recovery liquid, one or more of the conductivity, temperature, flow rate, chromaticity and turbidity of the NMMO solvent recovery liquid is adjusted according to formula (1) so that the P value is greater than or equal to 0.9412. The anion exchange resin can improve the chromaticity removal rate of the NMMO solvent recovery liquid. Experimental results show that by adjusting various parameters to adjust the P value from 0.6440 to 1.0562, the chromaticity removal rate of the NMMO solvent recovery liquid by the D201 strong alkaline macroporous anion exchange resin can be increased from 46.15% to 53.85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of a device for improving the chroma removal rate of NMMO solvent provided in an embodiment of the present application;

[0029] Figure 2 This is a schematic structural diagram of a second embodiment of the device for improving the chroma removal rate of NMMO solvent provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] It should be understood that the expression "one or more of" includes individually each of the items recited after the expression and various combinations of two or more of the recited items, unless otherwise apparent from the context and usage. The expression "and / or" in conjunction with three or more recited items should be understood to have the same meaning, unless otherwise apparent from the context.

[0031] The terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, e.g., not excluding other unrecited elements or steps, unless otherwise specifically stated or understood from the context.

[0032] It should be understood that the order of steps or the order in which certain actions are performed are not important as long as the present invention remains operable. Additionally, two or more steps or actions may be performed simultaneously.

[0033] The use of any and all examples or exemplary language, such as "such as" or "including," herein is intended merely to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0034] In addition, the numerical ranges and parameters used to define the present invention are approximate values. The relevant numerical values in the specific examples have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise expressly stated, all ranges, amounts, values, and percentages used in this disclosure should be understood to be modified by the word "about." As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specified value or range.

[0035] The present application provides a method for improving the chroma removal rate of NMMO solvent, comprising:

[0036] The NMMO solvent recovery liquid is subjected to adsorption treatment using an anion exchange resin, and one or more of the conductivity, temperature, flow rate, color, and turbidity of the NMMO solvent recovery liquid is adjusted according to formula (1) so that the P value is greater than or equal to 0.9412:

[0037]

[0038] In formula (1), G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0039] This application uses NMMO solvent recovery liquid as raw material and uses anion exchange resin to perform adsorption treatment on it. In some specific implementations, the NMMO solvent recovery liquid is NMMO solvent recovered from the Lyocell fiber spinning coagulation bath, which can be obtained according to the following method:

[0040] The NMMO solution in the spinning coagulation bath is coagulated and then filtered to obtain an NMMO solvent recovery liquid.

[0041] In some specific implementations, polyacrylamide (PAM) flocculant is used to perform coagulation treatment, and then filtered to obtain NMMO solvent recovery liquid. The present application does not specifically limit the specific parameters of the coagulation treatment and filtration, and those skilled in the art can select them according to their needs.

[0042] In some specific implementations, after filtration and before anion exchange resin adsorption treatment, the temperature of the NMMO solvent recovery liquid is generally 20°C to 30°C, the conductivity of the NMMO solvent recovery liquid is generally 55μs / cm to 75μs / cm, and the flow rate of the NMMO solvent recovery liquid is generally 30m 3 / h~40m 3 / h, the chromaticity of the NMMO solvent recovery liquid is generally 300-500, and the turbidity is generally 10-20.

[0043] After obtaining the NMMO solvent recovery liquid, the NMMO solvent recovery liquid is subjected to adsorption treatment using an anion exchange resin. In some specific implementations, the anion exchange resin is D201 strongly basic macroporous anion exchange resin. The present application does not particularly limit the specific parameters of the adsorption treatment, and those skilled in the art can select them as needed.

[0044] In some specific implementations, the present application further includes using a cation exchange resin to perform adsorption treatment on the NMMO solvent recovery liquid after adsorption by the anion exchange resin. The present application does not specifically limit the specific type of the cation exchange resin and the specific parameters of the adsorption treatment, and those skilled in the art can select as needed.

[0045] When the anion exchange resin is used in the present application to perform adsorption treatment on the NMMO solvent recovery liquid, one or more of the conductivity, temperature, flow rate, chromaticity and turbidity of the NMMO solvent recovery liquid is adjusted according to formula (1) so that the P value is greater than or equal to 0.9412:

[0046]

[0047] In formula (1), G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0048] The applicant has discovered that when the P value calculated according to formula (1) is ≥ 0.9413, the anion exchange resin, particularly the D201 strongly basic macroporous anion exchange resin, can achieve a color removal rate of over 50% for the NMMO solvent recovery liquid. Therefore, by adjusting one or more parameters of the NMMO solvent recovery liquid, including conductivity, temperature, flow rate, color, and turbidity, to maintain the P value above 0.9413, the color removal rate of the NMMO solvent recovery liquid using the anion exchange resin can be improved.

[0049] The present application has no special restrictions on the method for adjusting the parameters such as conductivity, temperature, flow rate, chromaticity and turbidity of the NMMO solvent recovery liquid. It is preferred to adjust the chromaticity, turbidity and conductivity first, and then adjust the temperature and flow rate. Specifically, the temperature of the NMMO solvent recovery liquid can be increased by a heating device or decreased by a cooling device, the flow rate of the NMMO solvent recovery liquid can be increased or decreased by a valve, and the conductivity, chromaticity and turbidity can be controlled by adjusting the parameters of the coagulation treatment process, such as the amount of PAM flocculant added, thereby realizing automatic control of the NMMO solvent recovery process.

[0050] The present application also provides a device for improving the chroma removal rate of NMMO solvent, comprising:

[0051] Anion exchange resin adsorption unit;

[0052] Conductivity sensor, temperature sensor, flow sensor, colorimetry sensor and turbidity sensor respectively arranged at the liquid inlet of the anion exchange resin adsorption unit;

[0053] an adjustment unit, the adjustment unit including at least one of a flow adjustment unit for adjusting the flow rate of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a temperature adjustment unit for adjusting the temperature of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a turbidity adjustment unit for adjusting the turbidity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a chromaticity adjustment unit for adjusting the chromaticity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, and a conductivity adjustment unit for adjusting the conductivity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit;

[0054] a control unit, the control unit receiving conductivity data from the conductivity sensor, temperature data from the temperature sensor, flow data from the flow sensor, initial colorimetry data from the initial colorimetry sensor, turbidity data from the turbidity sensor, and processed colorimetry data from the processed colorimetry sensor, integrating the data according to formula (1) to obtain a P value, obtaining at least one of a temperature adjustment signal, a colorimetry adjustment signal, a turbidity adjustment signal, a conductivity adjustment signal, and a flow adjustment signal based on the P value, and sending the adjustment signal to a corresponding adjustment device;

[0055]

[0056] In formula (1), P ≥ 0.9412, G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0057] See also Figure 1 , Figure 1 Schematic diagram of the structure of the device for improving the chromaticity removal rate of NMMO solvent provided in an embodiment of the present application, wherein 1 is an anion exchange resin adsorption unit, 2 is a turbidity sensor, 3 is a colorimetry sensor, 4 is a conductivity sensor, 5 is a temperature sensor, 6 is a flow sensor, 7 is an adjustment unit, and 8 is a control unit.

[0058] The device for improving the chroma removal rate of NMMO solvent provided in an embodiment of the present application includes an anion exchange resin adsorption unit 1, which is used to adsorb the NMMO solvent to remove its chroma.

[0059] The device for improving the chromaticity removal rate of NMMO solvent provided in an embodiment of the present application includes a turbidity sensor 2, a chromaticity sensor 3, a conductivity sensor 4, a temperature sensor 5 and a flow sensor 6 respectively arranged at the liquid inlet of the anion exchange resin adsorption unit 1, the turbidity sensor 2 is used to detect the turbidity of the NMMO solvent recovery liquid entering the anion exchange resin adsorption unit 1, and send the detected turbidity to the control device 8; the chromaticity sensor 3 is used to detect the chromaticity of the NMMO solvent recovery liquid entering the anion exchange resin adsorption unit 1, and send the detected chromaticity to the control device 8; the conductivity sensor 4 is used to detect the conductivity of the NMMO solvent recovery liquid entering the anion exchange resin adsorption unit 1, and send the detected conductivity to the control device 8; the temperature sensor 5 is used to detect the temperature of the NMMO solvent recovery liquid entering the anion exchange resin adsorption unit 1, and send the detected temperature to the control device 8; the flow sensor 6 is used to detect the flow rate of the NMMO solvent recovery liquid entering the anion exchange resin adsorption unit 1, and send the detected flow rate to the control device 8. In some specific implementations, the turbidity sensor 2 can be a turbidity meter; the colorimetry sensor 3 can be a colorimeter; the conductivity sensor 4 can be a conductivity meter; the temperature sensor 5 can be a thermometer; the flow sensor 6 can be a flowmeter, etc., and this application has no special limitations.

[0060] The device for improving the chromaticity removal rate of NMMO solvent provided in the present application includes a control unit 8, which receives conductivity data from the conductivity sensor 4, temperature data from the temperature sensor 5, flow data from the flow sensor 6, color data from the color sensor 3, and turbidity data from the turbidity sensor 2, respectively, integrates the data according to formula (I) to obtain a P value, and obtains at least one of a temperature adjustment signal, a color adjustment signal, a turbidity adjustment signal, a conductivity adjustment signal, and a flow adjustment signal based on the P value, and sends the adjustment signal to the corresponding adjustment device;

[0061]

[0062] In formula (1), P ≥ 0.9412, G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0063] The device for improving the chromaticity removal rate of NMMO solvent provided in the present application includes an adjustment unit 7, which includes at least one of a flow adjustment unit for adjusting the flow rate of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a temperature adjustment unit for adjusting the temperature of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a turbidity adjustment unit for adjusting the turbidity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a color adjustment unit for adjusting the color of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, and a conductivity adjustment unit for adjusting the conductivity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit. The adjustment unit 7 receives at least one of a temperature adjustment signal, a color adjustment signal, a turbidity adjustment signal, a conductivity adjustment signal, and a flow adjustment signal sent by a control unit 8, and adjusts corresponding parameters according to the corresponding adjustment signal.

[0064] Specifically, the flow adjustment unit can be a valve that increases or decreases the flow rate according to the adjustment requirements; the temperature adjustment unit can be a heating device or a cooling device that can increase or decrease the temperature; the turbidity adjustment unit, the color adjustment unit and the conductivity adjustment unit can be respectively reagent dosing devices that adjust the turbidity, color and conductivity of the NMMO solvent recovery liquid by adding corresponding reagents.

[0065] In some specific implementations, the device for improving the chromaticity removal rate of NMMO solvent described in the present application further includes a coagulation unit 20 whose liquid outlet is connected to the liquid inlet of the anion exchange resin adsorption unit 1, see Figure 2 , Figure 2 This is a schematic structural diagram of a second embodiment of the device for improving the chroma removal rate of NMMO solvent provided in an embodiment of the present application, wherein 20 is a coagulation unit, 30 is a filtration unit, and 40 is a cation exchange resin adsorption unit.

[0066] The coagulation unit 20 is used to coagulate impurities in the NMMO solvent and adjust the conductivity, turbidity, and color of the NMMO solvent. In some specific implementations, the coagulation unit 20 can also function as a turbidity adjustment unit, a color adjustment unit, and a conductivity adjustment unit, adjusting the turbidity, color, and conductivity of the effluent by controlling the amount of flocculant added.

[0067] In some specific implementations, the apparatus for improving the chroma removal rate of NMMO solvent described in the present application further includes a filtration unit 30 disposed between the coagulation unit 20 and the anion exchange resin adsorption unit 1 to separate the solid and liquid obtained by coagulation.

[0068] In some specific implementations, the device for improving the chroma removal rate of NMMO solvent described in the present application further includes: a cation exchange resin adsorption unit 40 whose liquid inlet is connected to the liquid outlet of the anion exchange resin adsorption unit 1, for further removing impurities in the NMMO solvent.

[0069] When an anion exchange resin is used in the present application for adsorption treatment of NMMO solvent recovery liquid, the anion exchange resin's color removal rate for the NMMO solvent recovery liquid can be improved by adjusting one or more of the conductivity, temperature, flow rate, color, and turbidity of the NMMO solvent recovery liquid according to formula (1) to achieve a P value greater than or equal to 0.9412. Experimental results show that by adjusting various parameters to adjust the P value from 0.6440 to 1.0562, the color removal rate of the NMMO solvent recovery liquid using D201 strongly basic macroporous anion exchange resin can be increased from 46.15% to 53.85%.

[0070] The following is a further description of the device and method for improving the chroma removal rate of NMMO solvent provided in the present application in conjunction with the embodiments.

[0071] Examples 1 to 6, Comparative Examples 1 to 3

[0072] The spinning coagulation bath for preparing Lyocell fibers was coagulated and then filtered to obtain NMMO solvent recovery liquid. The coagulation treatment effect was controlled according to the parameters shown in Table 1. The NMMO solvent recovery liquid was treated with D201 strong alkaline macroporous anion exchange resin. The chromaticity of the treated NMMO solvent was measured, the chromaticity removal rate was calculated, and the P value was calculated according to formula (1):

[0073]

[0074] In formula (1), G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

[0075] The results are shown in Table 1, which shows the color removal results of the examples and comparative examples of the present application.

[0076] Table 1 Color removal results of the examples and comparative examples of the present application

[0077]

[0078]

[0079] As shown in Table 1, when the P value is ≥ 0.9413, the chromaticity removal rate of the anion exchange resin for the NMMO solvent reaches more than 50%.

[0080] Example 7

[0081] The chroma of Comparative Example 1 was adjusted to 380, the turbidity to 13, the P value to 0.9421, and the chroma removal rate to 50.5%.

[0082] Example 8

[0083] The temperature of Comparative Example 2 was adjusted to 28° C., so that the P value was 0.99 and the chroma removal rate could reach 52%.

[0084] Example 9

[0085] Adjust the flow rate of comparative example 3 to 40m 3 / h, making the P value 0.9469 and the chroma removal rate up to 51.1%.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for improving the chromaticity removal rate of NMMO solvent, characterized in that: include: The NMMO solvent recovery liquid is subjected to adsorption treatment using an anion exchange resin, and one or more of the conductivity, temperature, flow rate, color, and turbidity of the NMMO solvent recovery liquid is adjusted according to formula (1) so that the P value is greater than or equal to 0.9412: In formula (1), G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

2. The method according to claim 1, characterized in that The anion exchange resin is D201 strongly basic macroporous anion exchange resin.

3. The method according to claim 2, characterized in that The NMMO solvent recovery liquid is obtained according to the following method: The NMMO solution in the spinning coagulation bath is coagulated and then filtered to obtain an NMMO solvent recovery liquid.

4. The method according to claim 3, characterized in that Also includes: The NMMO solvent recovery liquid treated with the anion exchange resin is adsorbed by using a cation exchange resin.

5. The method according to any one of claims 1 to 4, characterized in that The temperature of the NMMO solvent recovery liquid is 20°C to 30°C; The conductivity of the NMMO solvent recovery liquid is 55 μs / cm to 75 μs / cm; The flow rate of the NMMO solvent recovery liquid is 30m 3 / h~40m 3 / h.

6. A device for improving the chroma removal rate of NMMO solvent, characterized in that: include: Anion exchange resin adsorption unit; A conductivity sensor, a temperature sensor, a flow sensor, a colorimetry sensor, and a turbidity sensor are respectively arranged at the liquid inlet of the anion exchange resin adsorption unit; an adjustment unit, the adjustment unit including at least one of a flow adjustment unit for adjusting the flow rate of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a temperature adjustment unit for adjusting the temperature of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a turbidity adjustment unit for adjusting the turbidity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, a chromaticity adjustment unit for adjusting the chromaticity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit, and a conductivity adjustment unit for adjusting the conductivity of the NMMO solvent recovery liquid at the liquid inlet of the anion exchange resin adsorption unit; a control unit, the control unit receiving conductivity data from the conductivity sensor, temperature data from the temperature sensor, flow data from the flow sensor, colorimetry data from the colorimetry sensor, and turbidity data from the turbidity sensor, integrating the data according to formula (1) to obtain a P value, obtaining at least one of a temperature adjustment signal, a colorimetry adjustment signal, a turbidity adjustment signal, a conductivity adjustment signal, and a flow adjustment signal based on the P value, and sending the adjustment signal to a corresponding adjustment device; In formula (1), P ≥ 0.9412, G is the conductivity of the NMMO solvent recovery liquid, in μs / cm; T is the temperature of the NMMO solvent recovery liquid, in °C; Q is the flow rate of the NMMO solvent recovery liquid, in m 3 / h; M is the chromaticity of the NMMO solvent recovery liquid, the unit is Hazen; a is a constant, a is 0.13-0.17; N is the turbidity of the NMMO solvent recovery liquid, the unit is NTU.

7. The device according to claim 6, characterized in that Also includes: A coagulation unit whose liquid outlet is connected to the liquid inlet of the anion exchange resin adsorption unit.

8. The device according to claim 7, characterized in that The invention also includes a filtration unit arranged between the coagulation unit and the anion exchange resin adsorption unit.

9. The device according to claim 8, characterized in that Also includes: A cation exchange resin adsorption unit whose liquid inlet is connected to the liquid outlet of the anion exchange resin adsorption unit.

10. The device according to claim 6, characterized in that The anion exchange resin is D201 strongly basic macroporous anion exchange resin.

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