PREPARATION METHOD AND DEVICE FOR PRODUCING RECYCLED FIBER SPINNING SOLUTION USING SOLVENT METHOD

Abstract

The invention discloses a preparation method and a production device for producing a recycled fiber spinning solution with using a solvent, which comprises two or more vertical wiped film evaporators (3, 4, . . . ) connected with a single horizontal cylindrical kneading reactor. The aqueous mixture of cellulose and solvent and auxiliary agent is prepared into a spinnable cellulose spinning dope, which is characterized by injecting the material mixture into two or more vertical wiped film evaporators and a horizontal cylindrical kneading reactor, each unit is preferably equipped with a separate condensing system, and the vacuum system can be separately configured to share a vacuum system.

Claims

1. A method for preparing a regenerated cellulose fiber spinning dope by a solvent method, wherein an aqueous mixture of cellulose and a solvent and an auxiliary agent is prepared into a spinnable cellulose spinning dope, wherein the material mixture is first injected into two or more vertical wiped film evaporators (3, 4), then injected into a horizontal kneading reactor (9) connected thereto and evaporated and mixed under vacuum, wherein each of the wiped film evaporators (3, 4) is directly connected by a connecting section to the kneading reactor (9).

2. The method according to claim 1, wherein the connecting section adopts a pump or a screw pushing material or a gravity blanking method for material conveying through the pipeline or adopts a direct manner.

3. The method of claim 1, wherein each of the individual vertical wiped film evaporators (3, 4) and the kneading reactor (9) unit are each provided with a separate condensing system.

4. The method according to claim 1, wherein the vacuum system of each of the individual vertical wiped film evaporators (3, 4) and the kneading reactor(9) can be separately configured or shared or the wiped film evaporator (3, 4) shares a set of vacuum systems.

5. The method of claim 1, wherein each individual vertical wiped film evaporator (3, 4) and kneading reactor (9) unit operates at different vacuum pressures or at the same vacuum pressure.

6. The method according to claim 1, wherein the solvent is NMMO or other solvent which can dissolve cellulose.

7. The method of claim 1, wherein the mixture evaporates moisture in the vertical wiped film evaporators (3, 4) and increases the solvent concentration but is less than the concentration required for cellulose dissolution.

8. The method according to claim 7, wherein the NMMO is concentrated to a level above the monohydrate, using a solvent dominated by NMMO.

9. The method according to claim 1, wherein in the kneading reactor (9), the material sent from the wiped film evaporators (3, 4) to the kneading reactor (9) increases the solvent dissolution concentration by evaporating moisture to the level of dissolution with cellulose is homogenized to form a spinnable solution.

10. The method according to claim 9, wherein the NMMO is concentrated to a level of monohydrate and the ratio of NMMO to water and NMMO is not less than 86.7%.

11. The method according to claim 1, wherein the wiped film evaporators (3, 4) jacket steam temperature is between 100-180° C. and the jacket hot water temperature is 80-105° C. and the kneading reactor (9) jacketed heat medium operates between 90-120° C.

12. The method according to claim 1, wherein the wiped film evaporators (3, 4) and the kneading reactor (9) are operated under a vacuum of 40-100 mbar under vacuum operation condition.

13. The method according to claim 12, wherein if the wiped film evaporators (3, 4) and the kneading reactor (9) operate at different degrees of vacuum, the vacuum pressure of the kneading reactor (9) is less than the vacuum of the wiped film evaporators (3, 4) pressure.

14. A method according to claim 1, wherein the evaporation of the material under vacuum requires condensation of the evaporated water vapor through a condenser, wherein the calculated amount of condensed water and the actual amount of condensed water are used to adjust the jacket heat medium temperature or the rotor speed or the degree of vacuum or a combination to control the extent of moisture evaporation in the spinning dope, wherein, if the actual amount of condensation is less than the amount of condensation required for calculation, it can be adjusted by increasing the temperature of the heat medium or increasing the number of revolutions of the rotor or lowering the vacuum pressure or using it in combination.

15. System comprising at least two vertical wiped film evaporators (3, 4) connected with a single horizontal, cylindrical, kneading reactor (9), wherein each of the wiped film evaporators (3, 4) is directly connected by a connecting section to the kneading reactor (9).

16. The method according to claim 1, wherein the horizontal kneading reactor is a cylindrical kneading reactor.

17. The method according to claim 8, wherein the ratio of NMMO to water and NMMO is lower than 86.7%.

18. The method according to claim 1, wherein the wiped film evaporators (3, 4) jacket steam temperature is between 100-150° C. and the kneading reactor (9) jacketed heat medium operates between 100-110° C.

19. The method according to claim 12, wherein the vacuum is 45-55 mbar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In the FIGS. 1 and 2, input lines 1, 2, condensors 5, 6 and wiped film evaporators 3, 4 are shown. Reference number 7 refers to either auger or straight transition, reference number 8 refers tor pump or auger or straight transition, reference number 9 refers to kneading reactor, reference number 10 refers to condensation.

[0034] The following embodiments illustrate the features and advantages of the present invention by taking two wiped film evaporator corresponding to a kneading reactor as an example; the drawings of the present invention are not unique, and multiple wiped film evaporations can be performed according to customer and capacity requirements. The device corresponds to a kneading reactor for different combinations.

[0035] The possibility of using more than two wiped film evaporators is indicated in the figures by showing the two wiped film evaporators without reference numbers on the right side of each figure.

DETAILED DESCRIPTION

[0036] Example 1 referring to FIG. 1 differs from example 2/FIG. 2 only with respect to the transitions 7, 8 between the wiped film evaporators 3, 4 and the kneading reactor 9. In contrast to example 2, the transitions 7, 8 of example 1 are not combined before entering the kneading reactor 9.

[0037] Example 2/FIG. 2: The cellulose mixture previously mixed with NMMO and the auxiliary agent was metered into the wiped film evaporators 3 and 4 separately through the input lines 1 and 2, and it was also possible to carry out separately.

[0038] The connecting sections can be set separately (FIG. 1) or concentrated first to one or more main pipes (FIG. 2) before being connected to the kneading reactor 9.

[0039] In the wiped film evaporator 3, 4, the injected mixture material is subjected to evaporation and concentration of water. The concentrated material is transferred from the wiped film evaporators 3 and 4 (which can be carried out simultaneously or separately) into the same corresponding kneading reactor 9.

[0040] In the wiped film evaporators 3 and 4, in the case where the jacket is heated, the mixture material is formed into a film from the wiped film evaporator and the material is evaporated under vacuum, and the cellulose is evaporated under vacuum. No dissolution was achieved during this process. In the kneading reactor 9, in the case of jacket heating, the material is thoroughly mixed with the solvent (NMMO) and partially evaporated to achieve cellulose dissolution, thereby forming a highly viscous spinnable dope. The spinning dope is then conveyed through a pipe and a pump body to a spinning machine through a discharge device for spinning.

[0041] In order to further increase the productivity, it is also possible to slightly increase the cellulose concentration in the dope, and then dilute it to a suitable spinnable cellulose spinning solution. Dilution is done through the input line in the discharge unit. It may also be diluted upstream of the kneading reactor upstream of the discharge device or dispersed at multiple locations simultaneously.

[0042] The dope is conveyed downstream of the discharge device by means of one or more pumps to the downstream processing and spinning device.

[0043] The secondary vapor generated in the wiped film evaporators 3 and 4 and the kneading reactor 9 is condensed by a correspondingly connected condenser.