A six-effect evaporation-condensation recovery device and method for fiber tow washing water

Abstract

This invention relates to a six-effect evaporation and condensation recovery device and method for washing water from polyvinyl alcohol fiber tows. The method includes the following steps: S1. Passing the pre-washed washing water from the fiber tow into a coagulation bath circulation unit (13); S2. Sending the washing water from the coagulation bath circulation unit (13) to a six-effect evaporator (15), the steam generated by evaporation in the six-effect evaporator (15) is sent through a pipeline to a mixing condenser (17) for condensation, and then sent to a buffer tank (18). The liquid at the bottom of the six-effect evaporator (15) is sent to a condensate collection tank (16), and the liquid collected in the condensate collection tank (16) is mixed with the liquid at the bottom outlet of the mixing condenser (17) in the buffer tank (18) for reuse in washing the fiber tows. This invention realizes the recovery and recycling of the washing water and steam energy of polyvinyl alcohol fiber tows, and continuously and stably provides a constant-temperature hot liquid.

Description

[0001] This application is a divisional application of application number 202011565831.5, filed on December 25, 2020, entitled "A Tow Washing Apparatus and Tow Washing Method". Technical Field

[0002] This invention relates to the field of polyvinyl alcohol fiber preparation, and more particularly to a six-effect evaporation, condensation and recovery device and method for washing water from fiber bundles. Background Technology

[0003] During the preparation of polyvinyl alcohol fibers, microorganisms easily accumulate in the fiber washing device, affecting the washing effect. The washing water used is primary water, resulting in high sulfate content in the wastewater and high wastewater treatment and reuse costs. Furthermore, the washing process removes sodium sulfate carried on the fibers, leading to high sodium sulfate consumption. Summary of the Invention

[0004] The purpose of this invention is to provide a filament washing device and a filament washing method to solve the problem of high consumption during the filament washing process.

[0005] To achieve the above-mentioned objectives, the present invention provides a tow washing device, comprising: a water washing unit, a filtration unit connected to the water washing unit, a coagulation bath circulation unit and a sodium sulfate dissolution unit connected to the filtration unit;

[0006] Along the washing direction of the filament bundle, the washing unit is provided with multiple washing tanks connected in sequence, and each washing tank is provided with a water inlet and a water outlet.

[0007] Along the washing direction of the filament bundle, the outlet of the water washing tank in the first section is connected to the inlet of the filter unit.

[0008] According to one aspect of the invention, the filtering unit includes a plurality of filters, and the plurality of filters are arranged in parallel.

[0009] According to one aspect of the present invention, the coagulation bath circulation unit comprises: a coagulation bath circulation tank and a coagulation bath circulation pump;

[0010] The coagulation bath circulation tank is connected to the outlet of the filtration unit;

[0011] The inlet of the coagulation bath circulation pump is connected to the coagulation bath circulation tank and is used to output the liquid at the bottom of the coagulation bath circulation tank.

[0012] According to one aspect of the invention, the Glauber's salt dissolving unit is connected to the outlet of the filtration unit.

[0013] According to one aspect of the invention, it further includes: a six-effect evaporator, a condensate collection tank, a mixing condenser, and a buffer tank;

[0014] The outlet of the coagulation bath circulation pump is connected to the top inlet of the six-effect evaporator via a pipeline;

[0015] The first tower top outlet of the six-effect evaporator is connected to the coagulation bath circulation tank via a pipeline;

[0016] The second top outlet of the six-effect evaporator is connected to the first top inlet of the mixing condenser.

[0017] The outlet of the six-effect evaporator is connected to the condensate collection tank via a pipeline.

[0018] The outlet of the mixing condenser is connected to the buffer tank via a pipeline.

[0019] According to one aspect of the invention, it further includes: a coagulation bath water tank and a first centrifugal pump unit;

[0020] The coagulation bath water tank is connected to the condensate collection tank and is used to collect the liquid overflowing from the condensate collection tank;

[0021] The first centrifugal pump unit is connected to the coagulation bath water tank and the buffer tank respectively, and is used to send the liquid in the coagulation bath water tank into the buffer tank.

[0022] According to one aspect of the present invention, a first branch pipe is provided on the pipeline connecting the first centrifugal pump unit to the buffer tank, and the first branch pipe is connected to the mechanical seal water pipeline of the first centrifugal pump unit.

[0023] According to one aspect of the invention, it further includes: a second centrifugal pump unit;

[0024] The second centrifugal pump unit is connected to the inlet of the buffer tank and the second section of the washing tank.

[0025] According to one aspect of the invention, the second inlet at the top of the mixing condenser can be selectively connected to an external water pipe or connected to the outlet of the second section of the washing tank via a water treatment system;

[0026] The inlet of the washing tank described in the first paragraph is connected to an external demineralized water pipe.

[0027] According to one aspect of the invention, each section of the washing tank is provided with guide rods at intervals for fixing the filament bundles;

[0028] The guide rod is a glass guide rod.

[0029] According to one aspect of the invention, each section of the washing tank is further connected to a drain pipe at its outlet.

[0030] To achieve the above-mentioned objective, the present invention provides a method for washing filament bundles, comprising the following steps:

[0031] S1. Along the washing direction of the filament bundle, demineralized water is introduced into the first washing tank in the washing unit, and primary water is introduced into the remaining washing tanks;

[0032] S2. The water output from the first water washing tank is fed into the coagulation bath circulation unit and / or the sodium sulfate dissolution unit, and the liquid output from the remaining water washing tanks is sent to the water treatment system. After passing the water treatment, it enters the primary water system for condensation in the mixing condenser.

[0033] According to one aspect of the present invention, in step S2, if the water output from the first section of the washing tank passes through the filtration unit and is then fed into the coagulation bath circulation unit, the output water passes through the coagulation bath circulation tank and is then fed into the six-effect evaporator, where it is evaporated and concentrated before being sent to the coagulation bath circulation tank.

[0034] According to one aspect of the present invention, in step S2, the steam generated by evaporation in the six-effect evaporator is sent through a pipeline to a mixing condenser to mix with the liquid input into the mixing condenser from the second inlet, and the resulting bottom liquid is sent to a buffer tank.

[0035] According to one aspect of the present invention, in step S2, the bottom liquid in the six-effect evaporator is sent to the condensate collection tank, and when the liquid level reaches a preset height, it overflows through the pipeline to the coagulation bath water-saving tank.

[0036] The first centrifugal pump unit connected to the coagulation bath water tank sends a portion of the liquid in the coagulation bath water tank to the buffer tank through a pipeline, and sends another portion of the liquid to the mechanical seal water pipeline of the first centrifugal pump unit through the first branch pipe, which is used to cool the first centrifugal pump unit and then return it to the condensate collection tank.

[0037] According to one aspect of the invention, in step S2, the second centrifugal pump unit delivers the constant-temperature liquid stored in the buffer tank to the inlet of the washing tank.

[0038] According to one aspect of the present invention, if the liquid output from the first washing tank is introduced into the sodium sulfate dissolving unit, the output liquid is mixed with the sodium sulfate in the sodium sulfate dissolving unit and then output to the coagulation bath circulation tank.

[0039] According to one aspect of the invention, the temperature of the demineralized water introduced into the washing tank of the first section is 42±3℃;

[0040] The water temperature for the first water flow into the washing tank in the second section is 42±3℃.

[0041] In this invention, the higher the temperature setting of the demineralized water and primary water in the washing tank, the higher the energy consumption. The lower the temperature, the lower the washing effect of the filaments. Based on production experience, setting the water temperature to 42±3℃ can meet the washing requirements of the filaments while achieving the optimal energy consumption of the washing process, thus achieving the optimal balance between washing and energy consumption.

[0042] According to one aspect of the present invention, in the process of manufacturing polyvinyl alcohol fibers, not only is the washing effect of the fiber bundle improved, but also the accumulation of microorganisms in the fiber bundle washing device is reduced, the sulfate content in the fiber bundle washing wastewater and the cost of wastewater treatment and reuse are reduced, as well as the consumption of sodium sulfate and demineralized water is reduced.

[0043] According to one aspect of the present invention, the washing unit is modified and divided into a multi-section washing tank structure. This allows for the separate washing of the fiber bundles using different types of water, which is highly beneficial for improving the washing effect and reducing the accumulation of microorganisms in the washing device. Furthermore, since the first washing tank is a pre-washing tank, the large amount of sodium sulfate carried on the fiber bundles is pre-washed and recycled. The second washing tank washes the fiber bundles, reducing the amount of sodium sulfate carried on them, thereby lowering the sodium sulfate content in the water discharged into the water treatment system. This reduces the sulfate content in the washing wastewater from the other washing tanks besides the first washing tank, further contributing to lowering the cost of wastewater reuse.

[0044] According to one aspect of the present invention, the water output from the first washing tank is filtered and purified by a filtration unit consisting of multiple filters arranged in parallel before being input into the subsequent coagulation bath circulation unit. This ensures the purity of the water entering the coagulation bath circulation unit, which is beneficial for ensuring the long-term stable operation of the coagulation bath circulation unit. Furthermore, by arranging multiple filters in parallel within the filtration unit, not only is the filtration efficiency of the present invention effectively improved, but the long-term stable operation of the filtration unit is also effectively guaranteed, avoiding the drawback of system shutdown due to clogging caused by an insufficient number of filters.

[0045] According to one aspect of the present invention, by recycling the discharged water from the first washing tank through a coagulation bath circulation unit, the sodium sulfate is effectively recovered, thereby reducing sodium sulfate consumption in the tow production process. Simultaneously, the discharged water is selectively added to a sodium sulfate dissolving unit to dissolve the sodium sulfate. This allows the water after sodium sulfate dissolution to be directly used in the tow production process, not only improving the utilization rate of the discharged water and simplifying the discharged water treatment process, but also simplifying the entire tow production process. Through the above setup, approximately 0.15 tons / ton of demineralized water and approximately 0.0084 tons / ton of sodium sulfate can be saved from polyvinyl alcohol fiber. Attached Figure Description

[0046] Figure 1The diagram schematically illustrates the structure of a tow washing apparatus according to one embodiment of the present invention. Detailed Implementation

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0048] When describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0049] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0050] like Figure 1 As shown, according to one embodiment of the present invention, a tow washing device includes: a washing unit 11, a filtration unit 12 connected to the washing unit 11, a coagulation bath circulation unit 13 and a sodium sulfate dissolution unit 14 connected to the filtration unit 12. In this embodiment, along the tow washing direction, the washing unit 11 is provided with multiple sequentially connected washing tanks 111a and 111b, and each washing tank 111a and 111b is provided with an inlet 1111a and 1111b and an outlet 1112a and 1112b, respectively. In this embodiment, along the tow washing direction, the outlet 1112a of the first washing tank 111a is connected to the filtration unit 12. In this embodiment, the washing tanks 111a and 111b have two sections, and can also be configured with more sections, while the structure of the other sections of the washing tank is consistent with the structure of the second section of the washing tank.

[0051] According to the present invention, the washing unit 11 is modified and divided into a multi-section washing tank structure. This allows for the separate washing of the filament bundles using different types of water, which is highly beneficial for improving the washing effect of the filament bundles and reducing the accumulation of microorganisms in the filament bundle washing device. In addition, it reduces the sulfate content in the washing wastewater of the washing tanks other than the first washing tank (i.e., because the first washing tank is for pre-washing, the large amount of sodium sulfate carried on the filament bundles is pre-washed and recycled, and the second washing tank washes the filament bundles, reducing the sodium sulfate carried on the filament bundles, thereby reducing the sodium sulfate content in the water discharged into the water treatment system), which is further beneficial for reducing the cost of wastewater reuse.

[0052] like Figure 1 As shown, according to one embodiment of the present invention, the filtering unit 12 includes a plurality of filters 121, and the plurality of filters 121 are arranged side by side. In this embodiment, the filtering unit 12 employs two filters 121 arranged side by side.

[0053] With the above configuration, the water output from the first washing tank is filtered and purified by a filtration unit consisting of multiple filters 121 arranged in parallel before being input into the subsequent coagulation bath circulation unit 13. This ensures the purity of the water entering the coagulation bath circulation unit, which is beneficial for ensuring the long-term stable operation of the coagulation bath circulation unit. Furthermore, by arranging multiple filters in parallel within the filtration unit, not only is the filtration efficiency of the invention effectively improved, but the long-term stable operation of the filtration unit is also effectively guaranteed, avoiding the drawback of system shutdown due to clogging caused by an insufficient number of filters.

[0054] like Figure 1 As shown, according to one embodiment of the present invention, the coagulation bath circulation unit 13 includes: a coagulation bath circulation tank 131 and a coagulation bath circulation pump 132. In this embodiment, the coagulation bath circulation tank 131 is connected to the outlet of the filter unit 12; the inlet of the coagulation bath circulation pump 132 is connected to the coagulation bath circulation tank 131 and is used to output the liquid at the bottom of the coagulation bath circulation tank 131. In this embodiment, the coagulation bath circulation tank 131 serves as a water seal vacuum to ensure the smooth flow of liquid in this scheme. In this embodiment, multiple coagulation bath circulation pumps 132 are arranged in parallel (e.g., two, three, etc.). By setting multiple coagulation bath circulation pumps 132, they can be used individually or in combination, resulting in higher working efficiency and effectiveness. This also helps to avoid the risk of the entire system shutting down due to damage to a single pump, enabling the device in this scheme to operate stably for a long period.

[0055] like Figure 1As shown, according to one embodiment of the present invention, the sodium sulfate dissolving unit 14 is connected to the outlet of the filtration unit 12. In this embodiment, the sodium sulfate dissolving unit 14 is connected to the coagulation bath circulation unit 13 at the outlet of the filtration unit 12, and control valves are respectively installed on the inlet pipes of the sodium sulfate dissolving unit 14 and the coagulation bath circulation unit 13, thereby enabling the liquid output from the filtration unit 12 to selectively flow into the sodium sulfate dissolving unit 14 and / or the coagulation bath circulation unit 13. In this embodiment, if the liquid output from the filtration unit 12 is input into the sodium sulfate dissolving unit 14, then after the sodium sulfate dissolution is completed, the liquid in the sodium sulfate dissolving unit 14 is transported to the coagulation bath circulation tank 131.

[0056] like Figure 1 As shown, according to one embodiment of the present invention, the tow washing device of the present invention further includes: a six-effect evaporator 15, a condensate collection tank 16, a mixing condenser 17, and a buffer tank 18.

[0057] In this embodiment, the outlet of the condensate bath circulation pump 132 is connected to the top inlet of the six-effect evaporator 15 via a pipeline. With this configuration, the condensate bath circulation pump 132 directly delivers the liquid from the condensate bath circulation tank 131 to the six-effect evaporator 15. In this embodiment, the first top outlet of the six-effect evaporator 15 is connected to the condensate bath circulation tank 131 via a pipeline. This configuration ensures that the liquid containing sodium sulfate, after concentration in the six-effect evaporator 15, returns to the condensate bath circulation tank 131, maintaining a stable sodium sulfate concentration in the condensate bath circulation tank 131, thus solving the problem of insufficient sodium sulfate concentration and achieving a high reuse rate of sodium sulfate. In this embodiment, the second top outlet of the six-effect evaporator 15 is connected to the first top inlet of the mixing condenser 17. With this configuration, the steam generated in the six-effect evaporator 15 can be directly fed into the mixing condenser 17, realizing the recovery of energy carried in the steam generated in the six-effect evaporator 15, thereby increasing the energy recovery efficiency and saving energy in this solution. In this embodiment, the outlet of the bottom of the six-effect evaporator 15 is connected to the condensate collection tank 16 via a pipeline. The condensate collection tank 16 also serves as a water-sealed vacuum, ensuring the normal and stable operation of the entire system. In this embodiment, the outlet of the bottom of the mixing condenser 17 is connected to the buffer tank 18 via a pipeline. The steam output from the six-effect evaporator 15 is condensed in the mixing condenser 17 and then recovered to form a constant-temperature hot liquid, which is then sent to the buffer tank 18 for buffering. This ensures a stable liquid supply to subsequent processes, which is beneficial for ensuring the normal and stable operation of this system. In this embodiment, the buffer tank is equivalent to the buffer tank for the water entering the washing tank, ensuring that the temperature and pressure of the water entering the washing tank are constant.

[0058] According to the present invention, by using a six-effect evaporator 15 to evaporate and concentrate the bath liquid in the coagulation bath circulation tank 131, the concentration of the bath liquid in the coagulation bath circulation tank 131 is ensured to be within the process requirement range, and the condensate generated by the evaporator is recycled.

[0059] like Figure 1 As shown, according to one embodiment of the present invention, the tow washing device of the present invention further includes: a coagulation bath water-saving tank 19 and a first centrifugal pump group 20. In this embodiment, the coagulation bath water-saving tank 19 is connected to a condensate collection tank 16 and is used to collect liquid overflowing from the condensate collection tank 16. In this embodiment, the first centrifugal pump group 20 is connected to both the coagulation bath water-saving tank 19 and a buffer tank 18, and is used to send the liquid in the coagulation bath water-saving tank 19 into the buffer tank 18. In this embodiment, the first centrifugal pump group 20 is also composed of multiple centrifugal pumps (such as two, three, or more), thereby enabling the single-unit operation or combined operation of the centrifugal pumps in the pump group, achieving flexible and stable operation of the entire system.

[0060] like Figure 1 As shown, according to one embodiment of the present invention, a first branch pipe 201 is provided on the pipeline connecting the first centrifugal pump set 20 and the buffer tank 18. The first branch pipe 201 is connected to the mechanical seal water pipeline of the first centrifugal pump set 20. The liquid output through the first branch pipe 201 can be used to cool the first centrifugal pump set 20, and then flows back to the condensate collection tank 16. This not only achieves cooling of the first centrifugal pump set 20, but also recovers the heat generated by the first centrifugal pump set 20, greatly improving the resource utilization rate of this solution.

[0061] like Figure 1 As shown, according to one embodiment of the present invention, the tow washing device of the present invention further includes a second centrifugal pump group 21. In this embodiment, the second centrifugal pump group 21 is connected to the buffer tank 18 and the inlet 1111b of the second section of the washing tank 111b. In this embodiment, the second centrifugal pump group 21 has multiple centrifugal pumps (e.g., two, three, or more). The centrifugal pumps in the second centrifugal pump group can operate individually or in combination, realizing flexible and stable operation, which is beneficial to ensuring the overall stability of the solution.

[0062] Through the above settings, the liquid in the water washing unit 11 is recycled in this solution, which effectively improves the resource utilization rate of the entire device.

[0063] like Figure 1As shown, according to one embodiment of the present invention, the second inlet 17a at the top of the mixing condenser 17 can be selectively connected to an external water pipe or connected to the outlet 1112b of the second-stage washing tank 111b via a water treatment system. Through this arrangement, the liquid in the washing tank 111b is reused, and its liquid is mixed with the steam output from the six-effect evaporator, recovering not only the steam but also the heat contained in the steam, effectively improving the resource utilization efficiency of this solution. Of course, when it is necessary to add water to the system, it can be connected through an external water pipe to ensure that the water circulation in the entire system remains stable.

[0064] In this embodiment, the inlet 1111a of the first water washing tank 111a is connected to the external demineralized water pipe.

[0065] According to one embodiment of the present invention, the outlets 1112a and 1112b of each section of the washing tank 111a and 111b are also connected to drain pipes. With the above arrangement, when the liquid in the washing tank is circulated too much and cannot be reused, the drain pipes facilitate the replenishment of new liquid to the entire system, so as to achieve the overall quality of washing the yarn bundle.

[0066] According to one embodiment of the present invention, the length ratio of the first washing tank 111a to the second washing tank 111b is 1:10. Research has found that this arrangement ensures the washing quality of the filament bundles. In particular, lengthening the second washing tank effectively improves the washing efficiency of this solution, saves washing time, and further synchronizes the washing processes of the two washing tanks, while reducing the consumption of demineralized water, ultimately lowering production costs.

[0067] According to one embodiment of the present invention, in the washing unit 11, each section of the washing tank 111a, 111b is provided with guide rods at intervals for fixing the filament bundle. In this embodiment, the guide rods are glass guide rods. In this embodiment, during the washing process of the filament bundle, since the filament bundle is prone to floating or agglomerating in the water, the guide rods are used to press the filament bundle up and down, controlling the water flow rate in the washing tank, thereby achieving a better washing effect. In this embodiment, the filament bundle passes between two glass guide rods, with a distance of 10-20 cm between the two glass guide rods. This not only restricts the way the filament bundle passes through but also acts as a liquid extractor, squeezing out the sodium sulfate solution carried in the filament bundle for reuse.

[0068] By setting guide rods between adjacent washing tanks, the filament bundle can be smoothly fed from the upstream washing tank to the downstream washing tank. This not only effectively eliminates the conveying obstacles caused by the separation of the upstream and downstream washing tanks, but also ensures the conveying efficiency of the filament bundle.

[0069] According to one embodiment of the present invention, the method for washing filament bundles includes the following steps:

[0070] S1. Along the fiber washing direction, demineralized water is introduced into the first washing tank 111a in the washing unit 11, and primary water is introduced into the remaining washing tanks 111b. It should be noted that the water entering the mixing condenser 17 is primary water, and the water entering the remaining washing tanks 111b is water that has been mixed and condensed by the mixing condenser 17, which can also be called primary water. "Primary water" refers to non-recycled water that can be used industrially after treatment from groundwater or river water.

[0071] S2. The water output from the first washing tank 111a is fed into the coagulation bath circulation unit 13 and / or the sodium sulfate dissolution unit 14. The liquid output from the remaining washing tank 111b is sent to the water treatment system. After passing the water treatment, it enters the primary water system for condensation in the mixing condenser 17.

[0072] like Figure 1 As shown, according to one embodiment of the present invention, in step S2, if the water output from the first section's washing tank 111a passes through the filtration unit 12 and is then fed into the coagulation bath circulation unit 13, the output water passes through the coagulation bath circulation tank 131 and is then fed into the six-effect evaporator 15, where it is evaporated and concentrated before being sent to the coagulation bath circulation tank 131.

[0073] like Figure 1 As shown, according to one embodiment of the present invention, in step S2, the steam generated by evaporation in the six-effect evaporator 15 is sent through a pipeline to the mixing condenser 17 to mix with the liquid input into the mixing condenser 17 from the second inlet 17a, and the resulting bottom liquid is sent to the buffer tank 18. In this embodiment, the buffer tank is equivalent to the buffer tank for the water inlet of the washing tank, ensuring that the temperature and pressure of the water entering the washing tank are constant.

[0074] like Figure 1 As shown, according to one embodiment of the present invention, in step S2, the liquid in the bottom of the six-effect evaporator 15 is sent to the condensate collection tank 16, and when the liquid level reaches a preset height, it overflows through the pipeline to the coagulation bath water-saving tank 19; in this embodiment, the first centrifugal pump group 20 connected to the coagulation bath water-saving tank 19 sends a portion of the liquid in the coagulation bath water-saving tank 19 to the buffer tank 18 through the pipeline, and sends another portion of the liquid through the first branch pipe 201 to the mechanical seal water pipeline of the first centrifugal pump group 20, for cooling the first centrifugal pump group 20 and then returning it to the condensate collection tank 16.

[0075] like Figure 1 As shown, according to one embodiment of the present invention, in step S2, the second centrifugal pump group delivers the constant temperature liquid stored in the buffer tank 18 to the inlet 1111b of the washing tank 111b.

[0076] like Figure 1 As shown, according to one embodiment of the present invention, if the liquid output from the first washing tank 111a is introduced into the sodium sulfate dissolving unit 14, the output liquid is mixed with the sodium sulfate in the sodium sulfate dissolving unit 14 and then output to the coagulation bath circulation tank 131. The liquid output here is actually the water after the fiber bundle is pre-washed, which washes away a large amount of sodium sulfate liquid carried on the fiber bundle. The sodium sulfate is dissolved using the pre-washed liquid and then enters the coagulation bath circulation tank for replenishment.

[0077] like Figure 1 As shown, according to one embodiment of the present invention, the temperature of the demineralized water introduced into the first section's washing tank 111a is 42±3℃.

[0078] The water temperature for the first water flow into the second section's washing tank 111b is 42±3℃.

[0079] According to the present invention, by segmenting the washing unit, different types of water are introduced into the washing tanks of different segments for washing the yarn bundles, which can effectively save water consumption for different water qualities. In particular, the amount of demineralized water used is effectively reduced, thus contributing to cost savings.

[0080] According to the present invention, by recycling the discharged water from the first washing tank through the coagulation bath circulation unit 13, the sodium sulfate is effectively recovered, thereby reducing the consumption of sodium sulfate in the tow production process. Simultaneously, the discharged water is selectively added to the sodium sulfate dissolving unit to dissolve the sodium sulfate. This allows the water after sodium sulfate dissolution to be directly used in the tow production process, not only improving the utilization rate of the discharged water and simplifying the discharged water treatment process, but also recovering the sodium sulfate in the discharged water and simplifying the entire tow production process. Through the above setup, approximately 0.15 tons / ton of demineralized water and approximately 0.0084 tons / ton of sodium sulfate can be saved from polyvinyl alcohol fiber.

[0081] The above description is merely an example of a specific solution of the present invention. For any devices and structures not described in detail herein, it should be understood that they are implemented using common devices and methods already available in the art.

[0082] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering washing water from fiber bundles through six-effect evaporation and condensation, comprising the following steps: S1. The washing water after pre-washing the filament bundle is introduced into the coagulation bath circulation unit (13); wherein, the coagulation bath circulation unit (13) is connected to the filtration unit (12), and the filtration unit (12) is connected to the water washing unit (11); the water washing unit (11) is provided with multiple water washing tanks (111a, 111b) connected in sequence along the washing direction of the filament bundle. S2. The washing water fed into the coagulation bath circulation unit (13) is sent to the six-effect evaporator (15). The steam generated by evaporation in the six-effect evaporator (15) is sent to the mixing condenser (17) through the pipeline for condensation and then sent to the buffer tank (18). The bottom liquid in the six-effect evaporator (15) is sent to the condensate collection tank (16). The liquid collected in the condensate collection tank (16) is mixed with the liquid at the bottom outlet of the mixing condenser (17) in the buffer tank (18) for reuse in washing the tow. In step S2, the steam generated by evaporation in the six-effect evaporator (15) is sent to the mixing condenser (17) through the pipeline and mixed with the liquid input into the mixing condenser (17) from the second inlet (17a). The resulting bottom liquid is then sent to the buffer tank (18). The second centrifugal pump group sends the constant temperature liquid stored in the buffer tank (18) to the inlet (1111b) of the second section of the water washing tank (111b).

2. The six-effect evaporation and condensation recovery method for washing water from fiber bundles according to claim 1, characterized in that, In step S2, the washing water that is introduced into the coagulation bath circulation unit (13) is fed into the six-effect evaporator (15) after passing through the coagulation bath circulation tank (131).

3. The six-effect evaporation and condensation recovery method for washing water from fiber bundles according to claim 2, characterized in that, In step S2, the bottom liquid of the six-effect evaporator (15) is sent into the condensate collection tank (16), and when the liquid level reaches the preset height, it overflows into the coagulation bath water-saving tank (19) through the pipeline. The first centrifugal pump group (20) connected to the coagulation bath water tank (19) sends a portion of the liquid in the coagulation bath water tank (19) to the buffer tank (18) through the pipeline, and sends another portion of the liquid to the mechanical seal water pipeline of the first centrifugal pump group (20) through the first branch pipe (201) for cooling the first centrifugal pump group (20) and then returning it to the condensate collection tank (16).

4. The six-effect evaporation and condensation recovery method for washing water from fiber bundles according to claim 1, characterized in that, In step S1, along the washing direction of the filament bundle, demineralized water is introduced into the washing tank (111a) in the first section of the washing unit (11) to pre-wash the filament bundle using the demineralized water. Water is introduced into the water washing tank (111b) of the second section.

5. The six-effect evaporation and condensation recovery method for washing water from fiber bundles according to claim 4, characterized in that, The temperature of the demineralized water introduced into the water washing tank (111a) of the first section is 42±3℃; The water temperature for the first water flow into the water washing tank (111b) of the second section is 42±3℃.

6. The six-effect evaporation and condensation recovery method for washing water of fiber bundles according to claim 4, characterized in that, The liquid output from the second section's washing tank (111b) is sent to the water treatment system. After passing the water treatment, it enters the primary water system for condensation in the mixing condenser (17).

7. A six-effect evaporation and condensation recovery apparatus for fiber tow washing water according to any one of claims 1-6, characterized in that, include: The coagulation bath circulation unit (13), the six-effect evaporator (15), the condensate collection tank (16), the mixing condenser (17) and the buffer tank (18) are used to receive the washing water after the pre-washing of the filament bundle. The outlet of the coagulation bath circulation unit (13) is connected to the top inlet of the six-effect evaporator (15); The second top outlet of the six-effect evaporator (15) is connected to the first top inlet of the mixing condenser (17); The bottom outlet of the six-effect evaporator (15) is connected to the condensate collection tank (16) via a pipeline; The bottom outlet of the mixing condenser (17) is connected to the buffer tank (18) via a pipeline; The liquid collected at the bottom outlet of the six-effect evaporator (15) is mixed with the liquid collected at the bottom outlet of the mixing condenser (17) in the buffer tank (18) for reuse in washing the filament bundle.

8. The six-effect evaporation, condensation, and recovery device for fiber bundle washing water according to claim 7, characterized in that, The coagulation bath circulation unit (13) includes: a coagulation bath circulation tank (131) and a coagulation bath circulation pump (132). The coagulation bath circulation tank (131) is connected to the first tower top outlet of the six-effect evaporator (15) via a pipeline; The inlet of the coagulation bath circulation pump (132) is connected to the coagulation bath circulation tank (131) to output the liquid at the bottom of the coagulation bath circulation tank (131); The outlet of the coagulation bath circulation pump (132) is connected to the top inlet of the six-effect evaporator (15) via a pipeline.

9. The six-effect evaporation, condensation, and recovery device for washing water of fiber bundles according to claim 7, characterized in that, Each of the aforementioned washing tanks (111a, 111b) is provided with an inlet (1111a, 1111b) and an outlet (1112a, 1112b). Along the washing direction of the filament bundle, the outlet (1112a) of the washing tank (111a) in the first section is connected to the inlet of the filter unit (12).

10. The six-effect evaporation, condensation, and recovery device for fiber bundle washing water according to claim 9, characterized in that, The filtering unit (12) includes a plurality of filters (121), and the plurality of filters (121) are arranged in parallel.

11. The six-effect evaporation, condensation, and recovery device for washing water of fiber bundles according to claim 10, characterized in that, Also includes: Condensation bath water tank (19), first centrifugal pump unit (20); The coagulation bath water tank (19) is connected to the condensate collection tank (16) to collect the liquid overflowing from the condensate collection tank (16); The first centrifugal pump unit (20) is connected to the coagulation bath water tank (19) and the buffer tank (18) respectively, so as to send the liquid in the coagulation bath water tank (19) into the buffer tank (18).

12. The six-effect evaporation, condensation, and recovery device for fiber bundle washing water according to claim 11, characterized in that, A first branch pipe (201) is provided on the pipeline connecting the first centrifugal pump group (20) and the buffer tank (18), and the first branch pipe (201) is connected to the mechanical seal water pipeline of the first centrifugal pump group (20).

13. The six-effect evaporation, condensation, and recovery device for fiber bundle washing water according to claim 12, characterized in that, Also includes: Second centrifugal pump unit (21); The second centrifugal pump unit (21) is connected to the buffer tank (18) and the inlet (1111b) of the second section of the washing tank (111b).

14. The six-effect evaporation, condensation, and recovery device for fiber bundle washing water according to claim 13, characterized in that, The second inlet (17a) at the top of the mixing condenser (17) can be selectively connected to an external water pipe or connected to the outlet (1112b) of the second section of the water washing tank (111b) through a water treatment system. The inlet (1111a) of the water washing tank (111a) described in the first paragraph is connected to the external demineralized water pipe.

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