Water removal and recovery system and water removal and recovery method for lifsi

Abstract

The present application provides a water removal and recovery system and water removal and recovery method for LiFSI. Specifically, two stages of thin-film evaporators connected in series are used to purify a crude LiFSI product, so that LiFSI with sufficiently high purity is obtained by means of a relatively simple configuration. A thin-film evaporator itself integrates an evaporation system and a condensation system, not only simplifying the system configuration of connecting piping or pipes, but also reducing resistance and reducing the risk of system leakage. In addition, after evaporation, a solvent and water can be effectively separated by means of a water separator, such that the content of an organic phase solvent in the separated water is very low and the content of water in the organic phase solvent is also very low. In this way, a solvent with high purity can be recovered as much as possible for reuse, and the treatment costs of wastewater can be reduced.

Description

Water removal recovery system and method for lithium bisfluorosulfonylimide TECHNICAL FIELD

[0001] The present application relates to the field of lithium bisfluorosulfonylimide preparation, in particular to a water removal recovery system and method for lithium bisfluorosulfonylimide. BACKGROUND

[0002] In the field of lithium batteries, lithium salt electrolyte is an important component of lithium batteries. Lithium bisfluorosulfonylimide has a wide application prospect in the field of lithium batteries due to its good performance in thermal stability, decomposition resistance and electrical conductivity. However, lithium bisfluorosulfonylimide is very sensitive to water and can easily decompose when it comes into contact with water, which may reduce the performance and service life of lithium batteries. In the existing water removal method of lithium bisfluorosulfonylimide, water is sometimes removed by adding a dehydrating agent, but this will result in the residual of impurities and the inability to obtain high-quality lithium bisfluorosulfonylimide.

[0003] Although some solutions for purifying lithium bisfluorosulfonylimide have been proposed by relevant technical personnel, the overall structure of the system for implementing these solutions is complex, and there is a lack of corresponding effective processing means for the separation and recovery of other solvents and water.

[0004] SUMMARY

[0005] The present application is made in view of the above state of the art. One object of the present application is to provide a water removal recovery system for lithium bisfluorosulfonylimide, which can purify the crude product of lithium bisfluorosulfonylimide with a relatively simple structure and also effectively recover other solvents and water. Another object of the present application is to provide a water removal recovery method for lithium bisfluorosulfonylimide as described above, which is implemented by using the above water removal recovery system.

[0006] In order to achieve the above objects, the present application adopts the following technical solutions.

[0007] The present application provides a water removal recovery system for lithium bisfluorosulfonylimide, comprising: a water separator for separating water and organic phase solvents for separate recovery; a first thin film evaporator comprising a first inlet, a first light component outlet and a first heavy component outlet, the first inlet being used to receive product liquid, the first light component outlet being in communication with the water separator; and a second thin film evaporator comprising a second inlet, a second light component outlet and a second heavy component outlet, the second inlet being in communication with the first heavy component outlet, the second light component outlet being in communication with the water separator.

[0008] In an alternative, the water trap comprises a first chamber and a second chamber, the first chamber being in communication with the first light component outlet and the second light component outlet, a partition being provided between the first chamber and the second chamber, liquid in the first chamber being able to overflow over the partition into the second chamber.

[0009] In another alternative, a first liquid level sensor and a first water trap regulating valve are further included, the first water trap regulating valve being connected to an outlet of the first chamber, the first water trap regulating valve being opened and closed based on a parameter detected by the first liquid level sensor, the first liquid level sensor being provided on the water trap to sense a liquid level of liquid in the first chamber; and / or a second liquid level sensor and a second water trap regulating valve are further included, the second water trap regulating valve being connected to an outlet of the second chamber, the second water trap regulating valve being opened and closed based on a parameter detected by the second liquid level sensor, the second liquid level sensor being provided on the water trap to sense a liquid level of liquid in the second chamber.

[0010] In another alternative, a waste water treatment device and a mixed solvent storage device are further included, the waste water treatment device being connected to an outlet of the first chamber, the mixed solvent storage device being connected to an outlet of the second chamber; and / or a first delivery pump and a second delivery pump are further included, the first delivery pump and the second delivery pump being connected to the first chamber and the second chamber respectively to deliver liquid in the first chamber and the second chamber out.

[0011] In another alternative, at least one of the first thin film evaporator and the second thin film evaporator is a short path thin film evaporator.

[0012] In another alternative, a drying device is further included, the drying device being in communication with the second heavy component outlet, lithium bisfluorosulfonylimide being obtained by drying heavy component material from the second thin film evaporator by the drying device.

[0013] In another alternative, a solvent recovery device and a poor solvent storage device are further included, the solvent recovery device being in communication with the drying device and the poor solvent storage device, such that poor solvent from the drying device is able to enter the solvent recovery device for recovery and then be stored in the poor solvent storage device.

[0014] In another alternative, a first temperature sensor and a first heat source regulating valve are included, the first heat source regulating valve being opened and closed based on a parameter detected by the first temperature sensor, the first heat source regulating valve being disposed in the first thin film evaporator, the first temperature sensor being configured to sense an operating temperature in the first thin film evaporator; and / or a second temperature sensor and a second heat source regulating valve are included, the second heat source regulating valve being opened and closed based on a parameter detected by the second temperature sensor, the second heat source regulating valve being disposed in the second thin film evaporator, the second temperature sensor being configured to sense an operating temperature in the second thin film evaporator.

[0015] In another alternative, a vacuum control device is included, the vacuum control device being connected to the first thin film evaporator and the second thin film evaporator to control an operating pressure.

[0016] In another alternative, a first pressure sensor and a first pressure regulating valve are included, the first thin film evaporator being in controlled communication with the vacuum control device via the first pressure regulating valve, the first pressure regulating valve being opened and closed based on a parameter detected by the first pressure sensor, the first pressure sensor being disposed in the first thin film evaporator and configured to sense an operating pressure in the first thin film evaporator; and / or a second pressure sensor and a second pressure regulating valve are included, the second thin film evaporator being in controlled communication with the vacuum control device via the second pressure regulating valve, the second pressure regulating valve being opened and closed based on a parameter detected by the second pressure sensor, the second pressure sensor being disposed in the second thin film evaporator and configured to sense an operating pressure in the second thin film evaporator.

[0017] In another alternative, a tail gas treatment device and a waste liquid treatment device are included, the tail gas treatment device and the waste liquid treatment device being connected to the vacuum control device to treat tail gas and waste liquid from the vacuum control device.

[0018] The application also provides a water removal and recovery method of lithium bisfluorosulfonimide, which uses the water removal and recovery system of lithium bisfluorosulfonimide according to any one of the above technical solutions. The water removal and recovery method comprises: a feeding step, in which product liquid containing lithium bisfluorosulfonimide, water and other solvents is transported into the first thin film evaporator through the first feeding port; a first evaporation and separation step, in which light component substances separated by the first thin film evaporator enter the water separator through the first light component discharge port to be separated and recovered in the water separator, and heavy component substances separated by the first thin film evaporator enter the second thin film evaporator through the first heavy component discharge port and the second feeding port; and a second evaporation and separation step, in which light component substances separated by the second thin film evaporator enter the water separator through the second light component discharge port to be separated and recovered in the water separator, and heavy component substances separated by the second thin film evaporator are transported out through the second heavy component discharge port.

[0019] In an optional solution, the water removal and recovery system further comprises a drying device, and the water removal and recovery method further comprises a drying step, in which the heavy component substances from the second thin film evaporator are dried and crystallized in the drying device to obtain lithium bisfluorosulfonimide.

[0020] In another optional solution, the water separator comprises a first chamber and a second chamber, a partition is arranged between the first chamber and the second chamber, and the water removal and recovery method further comprises a light component separation step, in which the light component substances entering the first chamber of the water separator contain water and organic phase solvents that are immiscible, and the organic phase solvents of the first chamber can overflow to the second chamber of the water separator through the partition.

[0021] By adopting the above technical solutions, the application provides a water removal and recovery system and method of lithium bisfluorosulfonimide. In the water removal and recovery system of lithium bisfluorosulfonimide, a water separator, a first thin film evaporator, a second thin film evaporator and a drying device are included. The water separator is used for separating water and organic phase solvents. The first thin film evaporator comprises a first feeding port, a first light component discharge port and a first heavy component discharge port, the first feeding port is used for receiving product liquid, the product liquid contains lithium bisfluorosulfonimide, water and other solvents, and the first light component discharge port is in communication with the water separator. The second thin film evaporator comprises a second feeding port, a second heavy component discharge port and a second light component discharge port, the second feeding port is in direct and continuous communication with the first heavy component discharge port, and the second light component discharge port is in communication with the water separator.

[0022] In this way, on the one hand, the two-stage thin film evaporator in series is used to purify the crude lithium bisfluorosulfonylimide product, so that a relatively simple structure is used to obtain lithium bisfluorosulfonylimide with a high enough purity, and the water content of the lithium bisfluorosulfonylimide can be controlled to be below 50 ppm (ppm represents parts per million). Moreover, the thin film evaporator itself integrates the evaporation system and the condensation system, and the two-stage thin film evaporators are directly connected to each other, which not only simplifies the system structure of the connecting pipeline or pipeline, but also reduces the resistance and reduces the risk of system leakage. On the other hand, the solvent and water after the purification and separation treatment can be effectively separated by the water separator, so that the content of the organic phase solvent in the separated water is within 2%, and the content of water in the organic phase solvent is within 0.1%. In this way, as much as possible, the high-purity solvent can be recycled for reuse, and the treatment cost of waste water can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a schematic diagram showing the topology of a water removal and recovery system for lithium bisfluorosulfonylimide according to an embodiment of the present application.

[0024] FIG. 2 is a flowchart showing a water removal and recovery method for lithium bisfluorosulfonylimide in FIG. 1.

[0025] BRIEF DESCRIPTION OF DRAWINGS

[0026] 1a water separator; 11 first chamber; 12 second chamber; 13 partition; 1b waste water treatment device; 1c mixed solvent storage device;

[0027] 2 first thin film evaporator; 21 first inlet; 22 first light component outlet; 23 first heavy component outlet;

[0028] 3 second thin film evaporator; 31 second inlet; 32 second light component outlet; 33 second heavy component outlet;

[0029] 4 drying device;

[0030] 5a vacuum control device; 5b tail gas treatment device; 5c waste liquid treatment device;

[0031] 6a solvent recovery device; 6b poor solvent storage device;

[0032] TC1 first temperature sensor; TC2 second temperature sensor; PC1 first pressure sensor; PC2 second pressure sensor; LC1 first liquid level sensor; LC2 second liquid level sensor; TV1 first heat source regulating valve; TV2 second heat source regulating valve; PV1 first pressure regulating valve; PV2 second pressure regulating valve; WV1 first water separation regulating valve; WV2 second water separation regulating valve; PU1 first delivery pump; PU2 second delivery pump. DETAILED DESCRIPTION

[0033] The exemplary embodiments of the present application will be described below with reference to the accompanying drawings. It is to be understood that the specific description is only for the purpose of teaching one skilled in the art how to implement the present application, and is not intended to limit the scope of the present application.

[0034] In the present application, the connection between two objects (including but not limited to between devices) means that the inlet of one object and the outlet of the other object are connected to each other, and the connection can or can not use some pipelines or pipes. In the drawings, the arrow on the connecting line representing the pipeline or pipe shows the flow direction of the fluid in the pipeline or pipe.

[0035] In the present application, "connection" includes always connection and controlled connection, where always connection means that the pipeline or pipe between two objects can always be in a connected state, and controlled connection means that the pipeline or pipe between two objects can be controlled to be in a connected state or a non-connected state.

[0036] In the present application, the "opening and closing" of various valves includes complete opening of the valve, complete closing of the valve, and controllable adjustment of the opening degree of the valve.

[0037] The following describes a water removal and recovery system for lithium bisfluorosulfonylimide according to an embodiment of the present application, with reference to the accompanying drawings.

[0038] (Water removal and recovery system for lithium bisfluorosulfonylimide according to an embodiment of the present application)

[0039] As shown in FIG. 1, the water removal and recovery system for lithium bisfluorosulfonylimide according to an embodiment of the present application can include a water separator 1a, a wastewater treatment device 1b, a mixed solvent storage device 1c, a first thin film evaporator 2, a second thin film evaporator 3, a drying device 4, a vacuum control device 5a, a tail gas treatment device 5b, a waste liquid treatment device 5c, a solvent recovery device 6a, and a poor solvent storage device 6b. In the water removal and recovery system, the two-stage thin film evaporators 2, 3 and the drying device 4 arranged in series can serve the purpose of purifying lithium bisfluorosulfonylimide, and can remove impurities and moisture in lithium bisfluorosulfonylimide, etc.; in addition, the water separator 1a, the wastewater treatment device 1b, the mixed solvent storage device 1c, the solvent recovery device 6a, and the poor solvent storage device 6b can effectively treat and recover the separated water and solvent, respectively, which is conducive to the recycling of the solvent and the treatment of the wastewater.

[0040] In the present embodiment, the water separator 1a can adopt a horizontal water separator to effectively separate water and organic phase solvent in the light component substance from the two-stage thin film evaporator. Specifically, as shown in FIG. 1, the water separator 1a is internally formed with a first chamber 11 and a second chamber 12, and a partition 13 is arranged between the first chamber 11 and the second chamber 12, and the first chamber 11 and the second chamber 12 are communicated with each other via a passage above the partition 13, so that after the liquid in the first chamber 11 including the incompatible water and organic phase solvent is full or close to full, the organic phase solvent in the upper layer can overflow into the second chamber 12, while the water in the lower layer can still remain in the first chamber 11. To this end, the first chamber 11 is always directly communicated with the first light component discharge port 22 of the first thin film evaporator 2 and the second light component discharge port 32 of the second thin film evaporator 3, and the light component substance separated from the two thin film evaporators 2, 3 will enter the first chamber 11 of the water separator 1a, thereby enabling the water and the organic phase solvent in the light component substance entering the water separator 1a to be fully separated from each other.

[0041] In addition, as shown in FIG. 1, the water recovery system further includes a first liquid level sensor LC1, a second liquid level sensor LC2, a first water separation regulating valve WV1, a second water separation regulating valve WV2, a first delivery pump PU1 and a second delivery pump PU2. The outlet at the bottom of the first chamber 11 is controlled to be communicated with the wastewater treatment device 1b via the first water separation regulating valve WV1, and the first water separation regulating valve WV1 is opened and closed based on the parameter detected by the first liquid level sensor LC1. The first liquid level sensor LC1 is arranged on the water separator 1a and is used to sense the liquid level of the liquid in the first chamber 11. The first water separation regulating valve WV1 and the first liquid level sensor LC1 can be electrically connected or signal connected. It can be understood that the electrical connection or signal connection can be indirectly realized by a controller, thereby realizing the control as described above. The electrical connection or signal connection described herein can be realized in the same way, and will not be repeated here. The outlet at the bottom of the second chamber 12 is controlled to be communicated with the mixed solvent storage device 1c via the second water separation regulating valve WV2, and the second water separation regulating valve WV2 is opened and closed based on the parameter detected by the second liquid level sensor LC2. The second liquid level sensor LC2 is arranged on the water separator 1a and is used to sense the liquid level of the liquid in the second chamber 12. The second water separation regulating valve WV2 and the second liquid level sensor LC2 can be electrically connected or signal connected. Further, the liquid from the first chamber 11 can be delivered to the wastewater treatment device 1b via the first delivery pump PU1, and the liquid from the second chamber 12 can be delivered to the mixed solvent storage device 1c via the second delivery pump PU2. It can be understood that the monitoring by the first liquid level sensor (liquid level meter) LC1 with high sensitivity ensures that the water in the first chamber 11 does not enter the second chamber 12, thereby realizing the effective separation of water and organic phase solvent.

[0042] In the present embodiment, the first thin film evaporator 2 is as shown in FIG. 1. The housing of the first thin film evaporator 2 is provided with a first inlet 21, a first light component outlet 22 and a first heavy component outlet 23. The first inlet 21 is located at the top of the first thin film evaporator 2 for receiving product liquid. The product liquid comprises lithium bisfluorosulfonylimide, water and other solvents. It can be appreciated that in the present application, the other solvents can include good solvents and poor solvents. The good solvents and the poor solvents can include, but are not limited to, alkoxyethane solvents selected from one or more of diethyl ether, diisopropyl ether, methyl tert-butyl ether, dimethoxyethane, diethoxyethane; ester solvents selected from one or more of methyl acetate, ethyl acetate, propyl acetate and butyl acetate; and nitrile solvents selected from one or more of acetonitrile, propionitrile and butyronitrile; nitroalkane solvents selected from one or more of nitromethane, nitroethane, nitropropane and nitrobutane; hydrocarbon solvents selected from one or more of pentane, hexane and heptane; aromatic hydrocarbon solvents selected from one or more of benzene, toluene and xylene; alcohol solvents selected from one or more of methanol, ethanol, propanol and butanol; ketone solvents selected from one or more of acetone, methyl ethyl ketone and methyl isopropyl ketone; and dialkyl carbonate solvents selected from one or more of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. The first light component outlet 22 is located at the bottom of the first thin film evaporator 2 and is in communication with the first chamber 11, such that light component substances from the first thin film evaporator 2 can enter the first chamber 11. The first heavy component outlet 23 is located at the side of the first thin film evaporator 2 for delivering heavy component substances from the first thin film evaporator 2 into the second thin film evaporator 3. The housing of the second thin film evaporator 3 is provided with a second inlet 31, a second light component outlet 32 and a second heavy component outlet 33. The second inlet 31 is located at the top of the second thin film evaporator 3, and the second inlet 31 is in communication with the first heavy component outlet 23 for receiving heavy component substances from the first thin film evaporator 2. The second light component outlet 32 is located at the bottom of the second thin film evaporator 3 and is in communication with the first chamber 11, such that light component substances from the second thin film evaporator 3 can enter the first chamber 11. The second heavy component outlet 33 is located at the side of the second thin film evaporator 3 for delivering heavy component substances from the second thin film evaporator 3 into the drying device 4.

[0043] In the present embodiment, the first thin film evaporator 2 and the second thin film evaporator 3 can adopt the same type of short path thin film evaporator and have the same internal structure for achieving thermal separation under certain operating pressure conditions. Such a short path thin film evaporator may, for example, include a cylindrical shell with a heating jacket, a rotor and an internal condenser, and is equipped with a wiper and an anti-splashing device on the fixed frame of the rotor. The internal condenser is located in the center of the short path thin film evaporator, and the rotor rotates between the cylindrical shell and the internal condenser. The working process is briefly described as follows: the material is added from the feed inlet at the top of the short path thin film evaporator, and is continuously and uniformly distributed on the heating surface by the rotor, and the wiper scrapes the material into a thin and turbulent liquid film and pushes it downward in a spiral shape. In this process, the light component material escapes from the heating surface, passes through a short path and almost without collision to the internal condenser to condense into a liquid and flow down the condenser tube (where the condensation of the internal condenser can be achieved by a cold source, and it is not necessary to set an adjusting valve for controlling the cold source), and is discharged through the light component discharge port at the bottom of the short path evaporator. The remaining heavy component material is collected in the channel below the heating zone and discharged through the heavy component discharge port on the side. The short path thin film evaporator integrates the external condenser into the internal part of the cylindrical shell, so that the gap between the condenser condenser tube outer wall and the heating wall of the cylindrical shell is as small as possible, so that the evaporated light component material moves a short distance and is quickly cooled to a liquid phase, reducing the liquid phase condensation time, improving the separation efficiency, and the system used in two stages in series greatly ensures the complete separation of the solvent, water and lithium bisfluorosulfonylimide.

[0044] In order to adjust the operating temperature of the first thin film evaporator 2, as shown in FIG. 1, the water removal recovery system further comprises a first temperature sensor TC1 and a first heat source adjusting valve TV1. The first heat source adjusting valve TV1 can be electrically connected or signal connected with the first temperature sensor TC1, the first heat source adjusting valve TV1 is opened and closed based on the parameter detected by the first temperature sensor TC1, the first heat source adjusting valve TV1 is arranged at the heat source inlet of the first thin film evaporator 2 for controlling the flow of the heat source, and the first temperature sensor TC1 is used to sense the operating temperature in the first thin film evaporator 2. As shown in FIG. 1, in order to adjust the operating temperature of the second thin film evaporator 3, the water removal recovery system further comprises a second temperature sensor TC2 and a second heat source adjusting valve TV2. The second heat source adjusting valve TV2 can be electrically connected or signal connected with the second temperature sensor TC2, the second heat source adjusting valve TV2 is opened and closed based on the parameter detected by the second temperature sensor TC2, the second heat source adjusting valve TV2 is arranged at the heat source inlet of the second thin film evaporator 3 for controlling the flow of the heat source, and the second temperature sensor TC2 is used to sense the operating temperature in the second thin film evaporator 3.

[0045] In this embodiment, as shown in Fig. 1, the drying device 4 is always in direct communication with the second heavy component outlet 33, and the heavy component material from the second thin film evaporator 3 can be dried by the drying device 4 to obtain lithium bisfluorosulfonylimide with very high purity (the moisture content can be controlled below 50 ppm). The outlet of the drying device 4 can be in communication with a packaging device, so that the lithium bisfluorosulfonylimide from the drying device 4 can be directly packaged.

[0046] In this embodiment, as shown in Fig. 1, in order to control the operating pressure in the first thin film evaporator 2 and the second thin film evaporator 3 by the vacuum recovery device, the vacuum control device 5a is in communication with the first thin film evaporator 2 and the second thin film evaporator 3. In addition, the water removal recovery system further comprises a first pressure sensor PC1, a first pressure regulating valve PV1, a second pressure sensor PC2 and a second pressure regulating valve PV2. The first thin film evaporator 2 is in controlled communication with the vacuum control device 5a via the first pressure regulating valve PV1, the first pressure regulating valve PV1 is electrically connected or signal connected with the first pressure sensor PC1, the first pressure regulating valve PV1 is opened or closed based on the parameter detected by the first pressure sensor PC1, and the first pressure sensor PC1 is arranged in the first thin film evaporator 2 for sensing the operating pressure in the first thin film evaporator 2. The second thin film evaporator 3 is in controlled communication with the vacuum control device 5a via the second pressure regulating valve PV2, the second pressure regulating valve PV2 is electrically connected or signal connected with the second pressure sensor PC2, the second pressure regulating valve PV2 is opened or closed based on the parameter detected by the second pressure sensor PC2, and the second pressure sensor PC2 is arranged in the second thin film evaporator 3 for sensing the operating pressure in the second thin film evaporator 3.

[0047] Further, as shown in Fig. 1, the vacuum control device 5a is also in communication with the water separator 1a and the solvent recovery device 6a for controlling the operating pressure in the water separator 1a and the solvent recovery device 6a. In addition, the vacuum control device 5a is always in direct communication with the tail gas treatment device 5b and the waste liquid treatment device 5c. In this way, the tail gas from the vacuum control device 5a can directly enter the tail gas treatment device 5b for treatment, and the waste liquid from the vacuum control device 5a can directly enter the waste liquid treatment device 5c for treatment, avoiding the adverse effects of tail gas and waste liquid on the normal operation of the vacuum control device 5a, and avoiding the pollution they may cause to the environment. In addition, the solvent recovery device 6a is always in direct communication with the drying device 4 and the poor solvent storage device 6b, so that the poor solvent from the drying device 4 can be stored in the poor solvent storage device 6b after being recovered in the solvent recovery device 6a.

[0048] The following describes a water removal recovery method based on the water removal recovery system of lithium bisfluorosulfonylimide according to an embodiment of the present application.

[0049] Specifically, as shown in FIG. 2, the water recovery method according to the present application includes a feeding step, a first evaporation separation step, a second evaporation separation step, a drying step, and a light component separation step, in which the feeding step, the first evaporation separation step, the second evaporation separation step, and the drying step can be sequentially performed.

[0050] A crude product liquid obtained by performing a lithiation reaction of a lithium salt and a bisfluorosulfonylimide in a reaction vessel. In the feeding step, a product liquid containing lithium bisfluorosulfonylimide, water, and other solvents after the crude product liquid is filtered through a filter device is transported into the first thin film evaporator 2 via the first inlet port 21.

[0051] In the first evaporation separation step, the product liquid transported into the first thin film evaporator 2 is evaporated and concentrated. The operating pressure of the first thin film evaporator 2 is interlocked controlled by the first pressure sensor PC1 and the first pressure regulating valve PV1 at -0.080 MPaG to -0.099 MPaG (where MPaG indicates gauge pressure). The operating temperature of the first thin film evaporator 2 is interlocked controlled by the first temperature sensor TC1 and the first heat source regulating valve TV1 at 10°C to 50°C. The light component substance containing water and organic phase solvents evaporated from the first thin film evaporator 2 enters the first chamber 11 of the water knockout drum 1a via the first light component outlet port 22 to be separated in the water knockout drum 1a, and the heavy component substance containing lithium bisfluorosulfonylimide enters the second thin film evaporator 3 via the first heavy component outlet port 23 and the second inlet port 31.

[0052] In the second evaporation separation step, the heavy component substance transported into the second thin film evaporator 3 is further evaporated and concentrated. The operating pressure and the operating temperature of the second thin film evaporator 3 can be the same as those of the first thin film evaporator 2. The light component substance evaporated from the second thin film evaporator 3 enters the first chamber 11 of the water knockout drum 1a via the second light component outlet port 32 to be separated in the water knockout drum 1a, and the heavy component substance enters the drying device 4 via the second heavy component outlet port 33.

[0053] In the drying step, the heavy component substance from the second thin film evaporator 3 is dried in the drying device 4, and further crystallized to obtain lithium bisfluorosulfonylimide having a sufficiently high purity.

[0054] Further, as shown in Fig. 2, the light component separation step can be performed simultaneously with the first evaporation separation step, the second evaporation separation step, and the drying step, or can be performed after the three steps. In the light component separation step, the light component substance entering the first chamber 11 of the water separator 1a contains water and organic phase solvent that are immiscible, and the organic phase solvent is allowed to overflow to the second chamber 12 of the water separator 1a over the partition 13 in a state where the first chamber 11 is full or nearly full, that is, the organic phase solvent on the upper layer in the first chamber 11 is allowed to overflow to the second chamber 12 of the water separator 1a from the gap between the top end of the partition 13 and the housing of the water separator 1a, while the water on the lower layer in the first chamber 11 is retained in the first chamber 11. In the light component separation step, the operating pressure P of the water separator 1a can be adjusted by the vacuum adjusting device 5a to be in the range of -0.099 MPaG ≤ P ≤ -0.080 MPaG, and the operating temperature T of the water separator 1a can be adjusted to be in the range of 50°C ≥ T ≥ 10°C. Under the above operating pressure and operating temperature, the water separator 1a can more fully separate the water and the organic phase solvent.

[0055] It should be understood that the above embodiments are only exemplary and are not intended to limit the present application. Those skilled in the art can make various modifications and changes to the above embodiments under the teachings of the present application without departing from the scope of the present application. Further, the following supplementary explanations are made.

[0056] i. In the above embodiments of the present application, two-stage short-path thin-film evaporators 2, 3 are used to effectively remove water from lithium bisfluorosulfonylimide and separate the solvent by using the difference in boiling points, without introducing a dehydrating agent, thereby avoiding the introduction of foreign substances that can cause excessive chlorine ions and acid ions in the product, and ensuring the quality of the lithium bisfluorosulfonylimide.

[0057] Further, the water-containing mixed solvent is separated into water and organic phase solvent by the water separator 1a. The water separator 1a has two chambers 11, 12. The first chamber 11 is connected to the wastewater treatment device 1b or not by interlocking control of the first liquid level sensor LC1 and the first water separation adjusting valve WV1 provided on the line, so that the solvent content in the discharged water is controlled to be within 2%, thereby reducing the difficulty of wastewater treatment. The organic phase solvent overflows to the second chamber 12 over the partition 13 as the liquid level rises, and the second chamber 12 is connected to the mixed solvent storage device 1c or not by interlocking control of the second liquid level sensor LC2 and the second water separation adjusting valve WV2 provided on the line, so that the water content in the discharged organic phase solvent is controlled to be within 0.1%.

[0058] ii.In the above embodiments of the present application, the evaporation system and the condensation system are integrated by using the short-path thin film evaporator 2, 3, which reduces the connecting pipes, instruments, valves, etc. between the systems, thereby eliminating the pipe resistance and reducing the risk of leakage of the connecting parts, ensuring the internal vacuum degree of the entire system, reducing the evaporation temperature, and reducing the energy consumption by 20%.

[0059] iii.In the above embodiments of the present application, the thin film evaporator 2, 3 in the water removal and recovery system of the present application is a short-path thin film evaporator, but the present application is not limited thereto. For example, other types of thin film evaporators can be used.

[0060] iv.In the above embodiments of the present application, a configuration including only the thin film evaporators 2, 3 connected in series and the water separator 1a communicating with both the thin film evaporators 2, 3 can be used, which can further simplify the structure of the entire water removal and recovery system. Correspondingly, the steps of the water removal and recovery method using such a system in the above embodiments can be simplified. It can be understood that various other components can be provided as needed on the basis of the above embodiments to achieve the desired functions to achieve other variants. Here, the structure of the other variants is not described in detail.

[0061] v.The system of the present application can realize continuous production, thereby greatly improving the production capacity and reducing the production cost of lithium bisfluorosulfonylimide, and improving the production efficiency of lithium bisfluorosulfonylimide.

Claims

1. A water removal recovery system of lithium bisfluorosulfonylimide, characterized by, comprises: a water knockout, which is used to separate water and organic phase solvent for recovery respectively, and which comprises a first chamber and a second chamber, a partition is arranged between the first chamber and the second chamber, liquid in the first chamber can overflow the partition into the second chamber; a first thin film evaporator, which is a short path thin film evaporator, and comprises a first inlet, a first light component outlet and a first heavy component outlet, the first inlet is used to receive product liquid, the product liquid comprises lithium bisfluorosulfonylimide, water and other solvents, the first light component outlet is in direct communication with the first chamber of the water knockout; a second thin film evaporator, which is a short path thin film evaporator, and comprises a second inlet, a second light component outlet and a second heavy component outlet, the second inlet is in communication with the first heavy component outlet, the second light component outlet is in direct communication with the first chamber of the water knockout; and a drying device, which is in communication with the second heavy component outlet, lithium bisfluorosulfonylimide is obtained after drying and crystallization of heavy component material from the second thin film evaporator by the drying device.

2. The water removal and recovery system of lithium bisfluorosulfonylimide according to claim 1, further comprising: a first liquid level sensor and a first water knockout regulating valve, the first water knockout regulating valve is connected to the outlet of the first chamber, the first water knockout regulating valve is opened and closed based on the parameter detected by the first liquid level sensor, the first liquid level sensor is arranged on the water knockout and is used to sense the liquid level of the liquid in the first chamber; and / or a second liquid level sensor and a second water knockout regulating valve, the second water knockout regulating valve is connected to the outlet of the second chamber, the second water knockout regulating valve is opened and closed based on the parameter detected by the second liquid level sensor, the second liquid level sensor is arranged on the water knockout and is used to sense the liquid level of the liquid in the second chamber.

3. The water removal and recovery system of lithium bisfluorosulfonylimide according to claim 1, further comprising: a wastewater treatment device and a mixed solvent storage device, the wastewater treatment device is connected to the outlet of the first chamber, and the mixed solvent storage device is connected to the outlet of the second chamber; and / or a first delivery pump and a second delivery pump, the first delivery pump and the second delivery pump are respectively connected to the first chamber and the second chamber to deliver the liquid in the first chamber and the second chamber. a solvent recovery device and a poor solvent storage device, the solvent recovery device is in communication with the drying device and the poor solvent storage device, so that the poor solvent from the drying device can enter the solvent recovery device for recovery and then be stored in the poor solvent storage device.

4. The water removal recovery system of lithium bisfluorosulfonimide according to claim 1, characterized by, 5. The water removal and recovery system of lithium bisfluorosulfonylimide according to any one of claims 1 to 4, further comprising: ​ further comprising a first temperature sensor and a first heat source regulating valve, the first heat source regulating valve being opened or closed based on a parameter detected by the first temperature sensor, the first heat source regulating valve being disposed in the first thin film evaporator, the first temperature sensor being configured to sense an operating temperature in the first thin film evaporator; and / or further comprising a second temperature sensor and a second heat source regulating valve, the second heat source regulating valve being opened or closed based on a parameter detected by the second temperature sensor, the second heat source regulating valve being disposed in the second thin film evaporator, the second temperature sensor being configured to sense an operating temperature in the second thin film evaporator.

6. The water removal recovery system of lithium bisfluorosulfonimide according to any one of claims 1 to 4, characterized in that, further comprising a vacuum control device connected to the first thin film evaporator and the second thin film evaporator to control an operating pressure.

7. The water removal and recovery system of lithium bisfluorosulfonimide according to claim 6, wherein further comprising a first pressure sensor and a first pressure regulating valve, the first thin film evaporator being connected to the vacuum control device via the first pressure regulating valve, the first pressure regulating valve being opened or closed based on a parameter detected by the first pressure sensor, the first pressure sensor being disposed in the first thin film evaporator and configured to sense an operating pressure in the first thin film evaporator; and / or the vacuum control device being connected to the first thin film evaporator and the second thin film evaporator to control an operating pressure. further comprising a second pressure sensor and a second pressure regulating valve, the second thin film evaporator being connected to the vacuum control device via the second pressure regulating valve, the second pressure regulating valve being opened or closed based on a parameter detected by the second pressure sensor, the second pressure sensor being disposed in the second thin film evaporator and configured to sense an operating pressure in the second thin film evaporator.

8. The water removal recovery system of lithium bisfluorosulfonimide according to claim 6, characterized by, further comprising a tail gas treatment device and a waste liquid treatment device connected to the vacuum control device to treat tail gas and waste liquid from the vacuum control device.

9. A method for recovering water-free lithium bisfluorosulfonylimide, characterized by, The water removal and recovery method of lithium bisfluorosulfonimide according to any one of claims 1 to 8, the water removal and recovery method comprising: a feeding step in which a product liquid containing lithium bisfluorosulfonimide, water and other solvents is fed into the first thin film evaporator via the first inlet port; a first evaporation and separation step in which light component substances separated by the first thin film evaporator are fed into the water separator via the first light component outlet port to be separated and recovered in the water separator, and heavy component substances separated by the first thin film evaporator are fed into the second thin film evaporator via the first heavy component outlet port and the second inlet port; a second evaporation and separation step in which light component substances separated by the second thin film evaporator are fed into the water separator via the second light component outlet port to be separated and recovered in the water separator, and heavy component substances separated by the second thin film evaporator are fed out via the second heavy component outlet port; and a drying step in which the heavy component substances from the second thin film evaporator are dried and crystallized in the drying device to obtain lithium bisfluorosulfonimide, The water removal recovery method further includes a light component separation step, wherein the light component material entering the first chamber of the water knockout includes a non-miscible water and organic phase solvent, the organic phase solvent of the first chamber is able to overflow over the partition to the second chamber of the water knockout.

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