Device and method for online recovery of sodium sulfate from polyvinyl alcohol fiber bundle

Abstract

The present invention relates to an online recovery device and method for sodium sulfate of polyvinyl alcohol fiber tow, the device comprising: a coagulation bath circulation unit (13) for receiving discharge water containing sodium sulfate after pre-washing of the tow, and a sodium sulfate dissolving unit (14) connected to the coagulation bath circulation unit (13) and for receiving discharge water containing sodium sulfate after pre-washing of the tow; the coagulation bath circulation unit (13) comprises: a coagulation bath circulation tank (131) and a coagulation bath circulation pump (132), the inlet of the coagulation bath circulation pump (132) being connected to the coagulation bath circulation tank (131) to output liquid at the bottom of the coagulation bath circulation tank (131). The present invention effectively recovers sodium sulfate, thereby reducing the consumption of sodium sulfate in the tow production process.

Description

[0001] This application is a divisional application with the application date of December 25, 2020, application number 202011565831.5, and the invention name: A yarn bundle washing device and a yarn bundle washing method. Technical Field

[0002] The invention relates to the field of polyvinyl alcohol fiber preparation, and in particular to an online recovery device and method for sodium sulfate of polyvinyl alcohol fiber tow. Background Art

[0003] In the process of preparing polyvinyl alcohol fiber, microorganisms are easily accumulated in the tow washing device, which affects the tow washing effect. The tow washing water uses primary water for tow washing, and the sulfate content in the tow washing wastewater is high, and the cost of wastewater treatment and reuse is high. During the tow washing process, the mirabilite carried on the tow is washed off and discharged into the sewage system, resulting in high consumption of mirabilite. Summary of the invention

[0004] The object of the present invention is to provide a tow washing device and a tow washing method to solve the problem of high consumption in the tow washing process.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a tow washing device, comprising: a water washing unit, a filtering unit connected to the water washing unit, a coagulation bath circulation unit and a mirabilite dissolving unit connected to the filtering unit;

[0006] Along the washing direction of the tow, the water washing unit is provided with a plurality of sequentially connected water washing tanks, and each section of the water washing tank is respectively provided with a water inlet and a water outlet;

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

[0008] According to one aspect of the present invention, the filter 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, 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 for outputting the liquid at the bottom of the coagulation bath circulation tank.

[0012] According to one aspect of the present invention, the mirabilite dissolution unit is connected to the outlet of the filtration unit.

[0013] According to one aspect of the present invention, it also includes: a six-effect evaporator, a condensed water 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 through a pipeline;

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

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

[0017] The tower kettle outlet of the six-effect evaporator is connected to the condensed water collecting tank through a pipeline;

[0018] The tower kettle outlet of the mixing condenser is connected with the buffer tank through a pipeline.

[0019] According to one aspect of the present invention, it also includes: a coagulation bath water-saving tank, a first centrifugal pump group;

[0020] The coagulation bath water-saving tank is connected to the condensed water collecting tank and is used to collect liquid overflowing from the condensed water collecting tank;

[0021] The first centrifugal pump group is respectively connected to the coagulation bath water-saving tank and the buffer tank, and is used for sending the liquid in the coagulation bath water-saving 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 group and the buffer tank, and the first branch pipe is connected to the machine sealing water pipeline of the first centrifugal pump group.

[0023] According to one aspect of the present invention, it further comprises: a second centrifugal pump group;

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

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

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

[0027] According to one aspect of the present invention, guide rods for fixing the tow are arranged at intervals in each section of the water washing tank;

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

[0029] According to one aspect of the present invention, the water outlet of each section of the water washing tank is also connected to a sewage pipe.

[0030] To achieve the above-mentioned object of the invention, the present invention provides a method for washing a tow, comprising the following steps:

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

[0032] S2. The water output from the first section of the washing tank is passed into the coagulation bath circulation unit and / or the Glauber's salt dissolution unit, and the remaining liquid output from the washing tank is sent to the water treatment system. After passing the water treatment, it enters the primary water system again for condensation in the mixing condenser.

[0033] According to one aspect of the present invention, in step S2, if the water output from the washing tank in the first section passes through the filtering unit and then enters the coagulation bath circulation unit, the output water passes through the coagulation bath circulation tank and then enters the six-effect evaporator, and is evaporated and concentrated in the six-effect evaporator and then 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 to a mixing condenser through a pipeline to mix with the liquid input into the mixing condenser from the second inlet, and the bottom liquid generated after mixing is sent to a buffer tank.

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

[0036] The first centrifugal pump group connected to the coagulation bath water-saving tank sends part of the liquid in the coagulation bath water-saving tank to the buffer tank through a pipeline, and sends the other part of the liquid to the machine sealing water pipeline of the first centrifugal pump group through a first branch pipe, which is used to cool the first centrifugal pump group and then return it to the condensate collection tank.

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

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

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

[0040] The temperature of the water introduced into the washing tank of the second stage is 42±3°C.

[0041] In the present invention, the higher the temperature setting of the desalted water and primary water in the washing tank, the higher the energy consumption. The tow washing effect will be reduced if the temperature is low. According to production experience, setting the water temperature to 42±3°C can meet the tow washing requirements while optimizing the energy consumption of water washing, thereby achieving an optimal balance between washing and energy consumption.

[0042] According to one scheme of the present invention, in the process of manufacturing polyvinyl alcohol fibers, not only the tow washing effect is improved, but also the accumulation of microorganisms in the tow washing device is reduced, the sulfate content in the tow washing wastewater and the cost of treating and recycling the wastewater are reduced, and the consumption of Glauber's salt and desalted water is also reduced.

[0043] According to one solution of the present invention, the washing unit is modified and divided into a multi-stage washing tank structure, so that the tow can be washed separately by using different water, which is very beneficial to improving the washing effect of the tow and reducing the accumulation of microorganisms in the tow washing device. In addition, since the first stage washing tank is for pre-washing, a large amount of mirabilite carried on the tow is pre-washed and then recycled, and the second stage washing tank washes the tow, the mirabilite carried on the tow is reduced, thereby reducing the mirabilite content in the water discharged into the water treatment system, achieving the reduction of the sulfate content in the washing drainage of other washing tanks except the first stage washing tank, which is further beneficial to reducing the cost of treating wastewater reuse.

[0044] According to one solution of the present invention, a filtering unit composed of a plurality of filters arranged in parallel filters the water output from the first water washing tank and purifies it before inputting it into the subsequent coagulation bath circulation unit, thereby ensuring the purity of the water entering the coagulation bath circulation unit, which is beneficial to ensuring the long-term stable operation of the coagulation bath circulation unit. In addition, by arranging a plurality of filters in parallel in the filtering unit, not only the filtering efficiency of the present invention is effectively improved, but also the filtering unit is effectively ensured to be able to operate stably for a long time, avoiding the disadvantage of the entire system being shut down due to blockage caused by a small number of filters.

[0045] According to one solution of the present invention, the discharged water in the first section of the water washing tank is recycled through a coagulation bath circulation unit, so that the sodium sulfate therein is effectively recovered, thereby reducing the consumption of sodium sulfate in the tow production process. At the same time, the discharged water is selectively added to the sodium sulfate dissolution unit for dissolving the sodium sulfate, so that the water after dissolving the sodium sulfate can be directly applied to the tow production process, which not only improves the utilization rate of the discharged water, simplifies the treatment process of the discharged water, but also simplifies the entire tow production process. Through the above-mentioned settings, desalted water can save about 0.15 tons / ton of polyvinyl alcohol fiber, and sodium sulfate can save about 0.0084 tons / ton of polyvinyl alcohol fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1A structural diagram schematically shows a tow washing device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship 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 referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

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

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

[0051] According to the present invention, the washing unit 11 is modified and divided into a multi-stage washing tank structure, so that the tow can be washed separately by using different water, which is very beneficial to improving the washing effect of the tow and reducing the accumulation of microorganisms in the tow washing device. In addition, the content of sulfate in the washing wastewater in the washing tanks other than the first stage is also reduced (that is, because the first stage washing tank is a pre-washing tank, a large amount of mirabilite carried on the tow is pre-washed and then recycled, and the second stage washing tank washes the tow, and the mirabilite carried on the tow is reduced, so the mirabilite content in the water discharged into the water treatment system is reduced), which is further beneficial to reducing the cost of treating wastewater reuse.

[0052] like Figure 1 As shown, according to one embodiment of the present invention, the filter unit 12 includes a plurality of filters 121, and the plurality of filters 121 are arranged in parallel with each other. In this embodiment, the filter unit 12 uses two filters 121 arranged in parallel.

[0053] Through the above arrangement, the filter unit composed of multiple filters 121 arranged in parallel filters and purifies the water output from the first water washing tank and then inputs it into the subsequent coagulation bath circulation unit 13, thereby ensuring the purity of the water entering the coagulation bath circulation unit, which is beneficial to ensuring the long-term stable operation of the coagulation bath circulation unit. In addition, by arranging multiple filters in parallel in the filter unit, this not only effectively improves the filtering efficiency of the present invention, but also effectively ensures that the filter unit can operate stably for a long time, avoiding the disadvantage of the entire system shutting down due to clogging caused by a small 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 filtration 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 plays the role of water seal vacuum to ensure the smooth flow of the liquid in this scheme. In this embodiment, a plurality of coagulation bath circulation pumps 132 are arranged in parallel (such as two, three, etc.). By setting the coagulation bath circulation pump 132 to multiple units, it can be used alone or in combination, so that its work efficiency and effectiveness are higher, and it is also beneficial to avoid the risk of damage to a single pump causing the entire system device to shut down, so that the device in this scheme can operate stably for a long time.

[0055] like Figure 1As shown, according to one embodiment of the present invention, the Glauber's salt dissolving unit 14 is connected to the outlet of the filtering unit 12. In this embodiment, the Glauber's salt dissolving unit 14 is connected to the outlet of the filtering unit 12 in communication with the coagulation bath circulation unit 13, and control valves are respectively provided on the access pipelines of the Glauber's salt dissolving unit 14 and the coagulation bath circulation unit 13, so that the liquid output by the filtering unit 12 can selectively flow into the Glauber's salt dissolving unit 14 and / or the coagulation bath circulation unit 13. In this embodiment, if the liquid output by the filtering unit 12 is input into the Glauber's salt dissolving unit 14, then after the Glauber's salt is dissolved, the liquid in the Glauber's salt 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 collecting tank 16, a mixing condenser 17 and a buffer tank 18.

[0057] In this embodiment, the outlet of the coagulation bath circulation pump 132 is connected to the top inlet of the six-effect evaporator 15 through a pipeline. Through the above arrangement, the coagulation bath circulation pump 132 directly delivers the liquid in the coagulation 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 coagulation bath circulation tank 131 through a pipeline. Through the above arrangement, the liquid containing mirabilite after concentration in the six-effect evaporator 15 returns to the coagulation bath circulation tank 131, ensuring the stability of the mirabilite concentration in the coagulation bath circulation tank 131, thereby solving the disadvantage of insufficient mirabilite concentration and making the reuse rate of mirabilite high. 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; through the above arrangement, the steam generated in the six-effect evaporator 15 can be directly passed into the mixing condenser 17, realizing the recovery of the energy carried in the steam generated in the six-effect evaporator 15, thereby making the energy recovery efficiency in this scheme higher and saving energy. In this embodiment, the tower kettle outlet of the six-effect evaporator 15 is connected to the condensate collection tank 16 through a pipeline, wherein the condensate collection tank 16 also plays the role of water seal vacuum, ensuring the normal and stable operation of the entire system. In this embodiment, the tower kettle outlet of the mixing condenser 17 is connected to the buffer tank 18 through a pipeline. The steam output by the six-effect evaporator 15 is condensed in the mixing condenser 17, and then recycled to form a constant temperature hot liquid, which is then sent to the buffer tank 18 for buffering, so that it can maintain a stable liquid supply to the subsequent process, which is beneficial to ensuring the normal and stable operation of this scheme. In this embodiment, the buffer tank is equivalent to the buffer tank for the water inlet of the water washing tank, ensuring that the water temperature and pressure entering the water washing tank are constant.

[0058] According to the present invention, the bath liquid in the coagulation bath circulation tank 131 is evaporated and concentrated by using a six-effect evaporator 15 to ensure that the concentration of the bath liquid in the coagulation bath circulation tank 131 is within the process requirement range, and the condensed water 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 the condensate collecting tank 16, and is used to collect the liquid overflowing from the condensate collecting tank 16. In this embodiment, the first centrifugal pump group 20 is respectively connected to the coagulation bath water-saving tank 19 and the 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), so that the single operation or combined operation of the centrifugal pumps in the pump unit can be realized, and the flexible and stable operation of the entire system is realized.

[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 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. The liquid output through the first branch pipe 201 can be used to cool the first centrifugal pump group 20, and then flows back to the condensate collection tank 16, which not only realizes the cooling of the first centrifugal pump group 20, but also recovers the heat generated by the first centrifugal pump group 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 respectively connected to the buffer tank 18 and the water inlet 1111b of the second section of the water washing tank 111b. In this embodiment, the centrifugal pumps in the second centrifugal pump group 21 are provided with multiple units (e.g., two, three or more units), and the centrifugal pumps in the second centrifugal pump group can be operated individually or in combination, realizing the flexibility and stability of the operation process, which is beneficial to ensuring the overall stability of this solution.

[0062] Through the above arrangement, the present solution realizes the recycling of the liquid in the water washing unit 11, 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 water outlet 1112b of the second water washing tank 111b through a water treatment system. Through the above arrangement, the liquid in the water washing tank 111b is reused, and its liquid is mixed with the steam output from the six-effect evaporator to not only recover the steam but also the heat 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 make the water circulation in the whole system in a stable state.

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

[0065] According to one embodiment of the present invention, the water outlets 1112a and 1112b of each washing tank 111a and 111b are respectively connected to drainage pipes. Through the above arrangement, when the liquid in the washing tank cannot be reused due to excessive circulation, the drainage pipes are helpful for replenishing new liquid in the entire system to achieve the overall quality of the tow washing.

[0066] According to an embodiment of the present invention, the length ratio of the first-stage washing tank 111a to the second-stage washing tank 111b is 1:10. Research has found that the above arrangement not only ensures the washing quality of the tow, but also effectively improves the washing efficiency of the present solution by lengthening the second-stage washing tank, saves washing time, and further synchronizes the washing processes of the front and rear washing tanks, while reducing the consumption of desalted water, and ultimately reducing production costs.

[0067] According to one embodiment of the present invention, in the washing unit 11, guide rods for fixing the filament bundles are arranged at intervals in each section of the washing tank 111a, 111b. In this embodiment, the guide rods are glass guide rods. In this embodiment, during the process of washing the filament bundles, since the filament bundles are easy to float or gather in the water, the guide rods are used to press the filament bundles up and down to control the water flow rate in the washing tank, thereby achieving a better washing effect. In this embodiment, the filament bundles pass between two glass guide rods, and the distance between the two glass guide rods is 10-20 cm. On the one hand, it limits the way the filament bundles pass through, and on the other hand, it plays the role of squeezing liquid, squeezing the mirabilite solution carried in the filament bundles for reuse.

[0068] By arranging guide rods between adjacent washing tanks, it is ensured that the filament bundle can be smoothly conveyed from the upstream washing tank to the downstream washing tank, which 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 tow washing method of the present invention comprises the following steps:

[0070] S1. Along the tow washing direction, desalted water is introduced into the washing tank 111a in the first section of 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 the water mixed and condensed by the mixing condenser 17, which can also be called primary water. "Primary water" refers to non-circulating water that can be used in industry after groundwater or river water is treated.

[0071] S2. The water output from the first section of the washing tank 111a is passed into the coagulation bath circulation unit 13 and / or the sodium sulfate dissolution unit 14, and the remaining liquid output from the washing tank 111b is sent to the water treatment system. After the water treatment is qualified, it enters the primary water system again 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 washing tank 111a of the first section passes through the filtering unit 12 and then enters the coagulation bath circulation unit 13, then the output water passes through the coagulation bath circulation tank 131 and then enters the six-effect evaporator 15, and is evaporated and concentrated in the six-effect evaporator 15 and then 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 to the mixing condenser 17 through a pipeline to mix the liquid input into the mixing condenser 17 from the second inlet 17a, and the bottom liquid generated after the mixing is sent to the buffer tank 18. In this embodiment, the buffer tank is equivalent to the buffer tank for water inlet of the water washing tank, ensuring that the temperature and pressure of the water entering the water washing tank are constant.

[0074] like Figure 1 As shown, according to one embodiment of the present invention, in step S2, the bottom liquid in the six-effect evaporator 15 is sent to the condensate collecting tank 16, and when the liquid level reaches a preset height, it overflows to the coagulation bath water-saving tank 19 through a pipeline; in this embodiment, the first centrifugal pump group 20 connected to the coagulation bath water-saving tank 19 sends a part of the liquid in the coagulation bath water-saving tank 19 to the buffer tank 18 through a pipeline, and sends the other part of the liquid to the machine sealing water pipeline of the first centrifugal pump group 20 through a first branch pipe 201, which is used to cool the first centrifugal pump group 20 and then return it to the condensate collecting 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 water 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 washing tank 111a of the first section is passed into the Glauber's salt dissolving unit 14, the output liquid is mixed with the Glauber's salt in the Glauber's salt dissolving unit 14 and then output to the coagulation bath circulation tank 131. The liquid output here is actually the water after pre-washing of the silk bundle, which washes away a large amount of Glauber's salt liquid carried on the silk bundle, and uses the above-mentioned pre-washing to dissolve the Glauber's salt, and then enters the coagulation bath circulation tank for correction.

[0077] like Figure 1 As shown, according to one embodiment of the present invention, the temperature of the desalted water introduced into the first-stage water washing tank 111a is 42±3°C;

[0078] The temperature of the water introduced into the second-stage washing tank 111b is 42±3°C.

[0079] According to the present invention, by arranging the washing unit in sections, different water is introduced into the washing tanks in different sections for washing the tow, which can effectively save the amount of water of different water qualities. In particular, the amount of desalted water is effectively reduced, which is beneficial to cost saving.

[0080] According to the present invention, the discharged water in the first stage of the water washing tank is recycled by the coagulation bath circulation unit 13, so that the mirabilite therein is effectively recovered, thereby reducing the mirabilite consumption in the tow production process. At the same time, the discharged water is selectively added to the mirabilite dissolving unit to dissolve the mirabilite, so that the water after dissolving the mirabilite can be directly applied to the tow production process, which not only improves the utilization rate of the discharged water, simplifies the treatment process of the discharged water, recovers the mirabilite in the discharged water, but also simplifies the entire tow production process. Through the above-mentioned settings, desalted water can save about 0.15 tons / ton of polyvinyl alcohol fiber, and mirabilite can save about 0.0084 tons / ton of polyvinyl alcohol fiber.

[0081] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0082] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An online recovery device for polyvinyl alcohol fiber tow thenardite, characterized in that: include: A coagulation bath circulation unit (13) for receiving the discharged water containing sodium sulfate after the pre-washing of the silk bundle, and a sodium sulfate dissolving unit (14) connected to the coagulation bath circulation unit (13) and for receiving the discharged water containing sodium sulfate after the pre-washing of the silk bundle; The coagulation bath circulation unit (13) comprises: a coagulation bath circulation tank (131) and a coagulation bath circulation pump (132), wherein an inlet of the coagulation bath circulation pump (132) is connected to the coagulation bath circulation tank (131) so as to output liquid at the bottom of the coagulation bath circulation tank (131); It also comprises: a water washing unit (11) and a filtering unit (12) connected to the water washing unit (11); along the tow washing direction, the water washing unit (11) is provided with a plurality of water washing tanks (111a, 111b) connected in sequence, and each section of the water washing tank (111a, 111b) is provided with a water inlet (1111a, 1111b) and a water outlet (1112a, 1112b); Along the tow washing direction, the water outlet (1112a) of the water washing tank (111a) in the first section is connected to the inlet of the filtering unit (12); The coagulation bath circulation tank (131) and the mirabilite dissolving unit (14) are both connected to the outlet of the filtering unit (12), and control valves are respectively provided on the access pipelines between the mirabilite dissolving unit (14) and the coagulation bath circulation tank (131).

2. The online recovery device for sodium sulfate of polyvinyl alcohol fiber tow according to claim 1, characterized in that: Also includes: Six-effect evaporator (15), condensate collecting tank (16), mixing condenser (17) and buffer tank (18), The outlet of the coagulation bath circulation pump (132) is connected to the top inlet of the six-effect evaporator (15) through a pipeline; The first tower top outlet of the six-effect evaporator (15) is connected to the coagulation bath circulation tank (131) through a pipeline; The second tower top outlet of the six-effect evaporator (15) is connected to the first tower top inlet of the mixing condenser (17); The tower bottom outlet of the six-effect evaporator (15) is connected to the condensed water collection tank (16) through a pipeline; The bottom outlet of the mixing condenser (17) is connected to the buffer tank (18) via a pipeline.

3. The online recovery device for sodium sulfate of polyvinyl alcohol fiber tow according to claim 2, characterized in that: The filtering unit (12) comprises a plurality of filters (121), and the plurality of filters (121) are arranged in parallel.

4. The online recovery device for sodium sulfate of polyvinyl alcohol fiber tow according to claim 2 or 3, characterized in that: Also includes: Coagulation bath water-saving tank (19), first centrifugal pump group (20); The coagulation bath water-saving tank (19) is connected to the condensed water collecting tank (16) to collect liquid overflowing from the condensed water collecting tank (16); The first centrifugal pump group (20) is respectively connected to the coagulation bath water-saving tank (19) and the buffer tank (18) so as to deliver the liquid in the coagulation bath water-saving tank (19) into the buffer tank (18).

5. The online recovery device for sodium sulfate of polyvinyl alcohol fiber tow according to claim 4, 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 machine sealing water pipeline of the first centrifugal pump group (20).

6. The online recovery device for sodium sulfate of polyvinyl alcohol fiber tow according to claim 4, characterized in that: Also includes: A second centrifugal pump unit (21); The second centrifugal pump group (21) is respectively connected to the buffer tank (18) and the water inlet (1111b) of the second section of the water washing tank (111b).

7. The online recovery device for sodium sulfate of polyvinyl alcohol fiber tow according to claim 4, 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 water outlet (1112b) of the second-stage water washing tank (111b) through a water treatment system; The water inlet (1111a) of the water washing tank (111a) in the first section is connected to an external demineralized water pipe.

8. A method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow using the device for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to any one of claims 1 to 7, comprising the following steps: S1. The discharged water containing the sodium sulfate after the pre-washing of the tow is passed into the coagulation bath circulation unit (13) and / or the sodium sulfate dissolution unit (14); S2. If the discharged water containing sodium sulfate after the pre-washing of the tow is passed 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).

9. The method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to claim 8, characterized in that: The following steps are also included: S3. If the discharge containing sodium sulfate after the pre-washing of the tow is passed into the coagulation bath circulation unit (13), the output water passes through the coagulation bath circulation tank (131) and is then input into the six-effect evaporator (15), and is evaporated and concentrated in the six-effect evaporator (15) and then sent to the coagulation bath circulation tank (131).

10. The method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to claim 9, characterized in that: In step S3, the steam generated by evaporation in the six-effect evaporator (15) is sent to the mixing condenser (17) through a pipeline to mix with the liquid input into the mixing condenser (17) from the second inlet (17a), and the bottom liquid generated after the mixing is sent to the buffer tank (18).

11. The method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to claim 10, characterized in that: In the step S3, the bottom liquid in the six-effect evaporator (15) is sent to the condensed water collection tank (16), and when the liquid level reaches a preset height, it overflows to the coagulation bath water-saving tank (19) through a pipeline; A first centrifugal pump unit (20) connected to the coagulation bath water-saving tank (19) delivers a portion of the liquid in the coagulation bath water-saving tank (19) to the buffer tank (18) through a pipeline, and delivers another portion of the liquid to the machine seal water pipeline of the first centrifugal pump unit (20) through a first branch pipe (201), so as to cool the first centrifugal pump unit (20) and then return it to the condensate collection tank (16).

12. The method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to claim 11, characterized in that: In the step S3, the second centrifugal pump group delivers the constant temperature liquid stored in the buffer tank (18) to the water inlet (1111b) of the washing tank (111b).

13. The method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to claim 9, characterized in that: In the step S1, deionized water is introduced into the water washing tank (111a) in the first section of the water washing unit (11) along the direction of washing the tow, and the tow is pre-washed with the deionized water; The remaining water washing tanks (111b) are fed with primary water.

14. The method for online recovery of sodium sulfate from polyvinyl alcohol fiber tow according to claim 13, characterized in that: The temperature of the deionized water introduced into the first stage water washing tank (111a) is 42±3°C; The temperature of the water introduced into the washing tank (111b) of the second stage is 42±3°C.

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