NMP (N-Methyl Pyrrolidone) purification device

Abstract

The utility model discloses an NMP (N-Methyl Pyrrolidone) purification device which comprises a dehydration tank assembly and a refining tank assembly, the dehydration tank assembly is used for carrying out dehydration treatment on the NMP waste liquid, the refining tank assembly is used for separating heavy metal components from the dehydrated NMP waste liquid, and an NMP purified liquid is output. The device is realized by adopting the dehydration tank assembly and the refining tank assembly, the NMP waste liquid is purified by applying the vacuum rectification principle, and compared with the traditional high-tower rectification, the device has the advantages of small components, small occupied area and no need of building a chemical industrial park, and can be built in a factory together with a battery cell production line; the environmental pollution is reduced; meanwhile, the transportation cost of the NMP waste liquid and the purification liquid is reduced.

Description

Technical Field

[0001] This utility model relates to an NMP purification device, belonging to the field of lithium-ion battery waste liquid recycling technology. Background Technology

[0002] N-Methyl pyrrolidone (NMP) is a highly soluble solvent widely used in the chemical industry due to its chemical stability and good thermal stability. In lithium-ion battery production, NMP is used as a solvent for cathode materials. During the coating process, the NMP in the electrode continuously volatilizes in the oven. Typically, the volatilized NMP is extracted and recovered during production, forming NMP waste liquid. Considering environmental protection and cost, the NMP waste liquid is usually purified to achieve NMP reuse. Currently, the mainstream NMP waste liquid purification technology is high-tower distillation. However, due to the excessive height of the distillation tower, it usually requires the construction of a chemical industrial park. Furthermore, high-tower distillation requires a large land area, making it difficult to construct within a lithium-ion battery factory. Utility Model Content

[0003] This invention provides an NMP purification device that solves the problems disclosed in the background art.

[0004] According to one aspect of this disclosure, an NMP purification apparatus is provided, including a dehydration tank assembly and a refining tank assembly; the dehydration tank assembly dehydrates NMP waste liquid, and the refining tank assembly separates heavy metal components from the dehydrated NMP waste liquid and outputs NMP purified liquid.

[0005] The aforementioned NMP purification unit is implemented using dehydration tank components and refining tank components. It utilizes the principle of vacuum distillation to purify NMP waste liquid. Compared with traditional high-tower distillation, these are all miniaturized components, occupying a small area, eliminating the need for a chemical industrial park, and can be built inside the factory along with the battery cell production line. This reduces environmental pollution and lowers the transportation costs of NMP waste liquid and purified liquid.

[0006] Furthermore, the dehydration tank assembly comprises multiple units, with the dehydration tank assembly and the refining tank assembly connected in series. The first dehydration tank assembly is externally connected to an NMP waste liquid storage tank. By performing multiple dehydration processes on the NMP waste liquid through multiple dehydration tank assemblies, water can be separated from the NMP waste liquid to the greatest extent, thereby improving the purity of the extracted NMP.

[0007] Furthermore, the dehydration tank assembly includes a dehydration tank, a first condenser reflux device, and a first reboiler. The inlet JL1 of the dehydration tank is used to input NMP waste liquid. The low-temperature end of the dehydration tank is provided with outlets CS1, CS2, and HS1. The inlet JS1 of the first condenser reflux device is connected to outlet CS2, the outlet CS3 of the first condenser reflux device is connected to HS1, the outlet CS4 of the first condenser reflux device is externally connected to the NMP waste liquid storage tank, and the outlet CS1 is used to output the water separated during the dehydration process that did not enter the first condenser reflux device. The high-temperature end of the dehydration tank is provided with outlets CL1, CL2, and HL1. The first reboiler is located between outlet CL2 and HL1, and outlet CL1 is used to output the dehydrated NMP waste liquid.

[0008] The components in the dehydration tank assembly are all miniaturized, which facilitates integration and reduces the overall power consumption of the NMP purification unit while also reducing its size and installation and transportation costs.

[0009] Furthermore, the outlet CS1 is connected to an NMP absorption tower; the outlet of the NMP absorption tower is connected to the inlet of the NMP waste liquid storage tank. NMP will inevitably be present in the separated water. Except for the condensed water, the remaining water is introduced into the NMP absorption tower, avoiding NMP waste. Furthermore, the introduced water can be used as spray water for the NMP absorption tower, reducing costs.

[0010] Furthermore, a first reflux pump is installed between the outlet CS3 and the return outlet HS1. The reflux flow rate is controlled by the first reflux pump, thereby controlling the separation efficiency of the dehydration tank.

[0011] Furthermore, the first condensation reflux device includes a first condenser and a first reflux tank connected in sequence. The inlet JS1 is the inlet of the first condenser, and the outlets CS3 and CS4 are both outlets of the first reflux tank. The evacuation port of the first reflux tank is connected in sequence to a first vacuum tank and a first vacuum pump. The first vacuum tank and the first vacuum pump maintain a negative pressure in the first reflux tank, lowering the boiling point of the material.

[0012] Furthermore, the refining tank assembly includes a refining tank, a second reflux condenser, and a second reboiler. The inlet JL2 of the refining tank is used to input the dehydrated NMP waste liquid. The low-temperature end of the refining tank is provided with outlets CY1, CY2, and return outlet HY1. The inlet JY1 of the second reflux condenser is connected to outlet CY2, and the outlet CY3 of the second reflux condenser is connected to return outlet HY1. Outlet CY1 is used to output the NMP purified liquid that did not enter the second reflux condenser. The high-temperature end of the refining tank is provided with outlets CL3, CL4, and HL2. The second reboiler is located between outlet CL4 and return outlet HL2. Outlet CL3 is used to output the separated heavy metal components.

[0013] The components in the refining tank assembly are all miniaturized, making them easy to integrate. This reduces the overall power consumption of the NMP purification unit while also reducing its size and installation and transportation costs.

[0014] Furthermore, a second reflux pump is installed between the liquid outlet CY3 and the liquid return outlet HY1. The reflux flow rate is controlled by the second reflux pump, thereby controlling the separation efficiency of the refining tank.

[0015] Furthermore, the second condensation reflux device includes a second condenser and a second reflux tank connected in sequence. The inlet JY1 is the inlet of the second condenser, and the outlet CY3 is the outlet of the second reflux tank. The evacuation port of the second reflux tank is connected in sequence to a second vacuum tank and a second vacuum pump. The second vacuum tank and the second vacuum pump maintain a negative pressure in the second reflux tank, lowering the boiling point of the material.

[0016] The beneficial effects achieved by this utility model are as follows: This utility model adopts a dehydration tank assembly and a purification tank assembly, and uses the principle of vacuum distillation to purify NMP waste liquid. Compared with traditional high-tower distillation, these are all miniaturized components, occupying a small area, eliminating the need to build a chemical industrial park, and can be built inside the factory together with the battery cell production line, reducing environmental pollution and lowering the transportation costs of NMP waste liquid and purified liquid. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an NMP purification device. Detailed Implementation

[0018] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0019] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure.

[0020] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0021] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0022] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0023] It should be noted that similar symbols and letters in the following figures represent similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0024] Furthermore, in the description of the embodiments of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features.

[0025] To address the issues of existing NMP purification devices requiring the construction of chemical industrial parks, requiring large land areas, and being difficult to build within lithium battery factories, this disclosure proposes a novel NMP purification device. Specifically, it uses miniaturized components to replace distillation columns and employs the principle of vacuum distillation to purify NMP waste liquid.

[0026] See Figure 1 , Figure 1 This is a schematic diagram of an NMP purification apparatus provided in an embodiment of the present disclosure. The NMP purification apparatus may include at least a dehydration tank assembly and a purification tank assembly. The dehydration tank assembly dehydrates the NMP waste liquid, and the purification tank assembly separates the heavy metal components from the dehydrated NMP waste liquid and outputs the NMP purified liquid.

[0027] It should be noted that the number of dehydration tank components depends on their dehydration effect. If the dehydration effect is strong, such as removing more than 95% of the water, then only one dehydration tank component is needed. However, the dehydration effect of commonly available dehydration tank components is generally around 80%. To ensure the dehydration effect, in some embodiments, multiple dehydration tank components are configured. These multiple dehydration tank components and the refining tank component are connected in series. The first dehydration tank component is connected to the NMP waste liquid storage tank 2. The first dehydration tank component can remove most of the water, the second dehydration tank component can remove most of the remaining water, and so on, thereby achieving a strong dehydration effect. By dehydrating the NMP waste liquid multiple times with multiple dehydration tank components, the water can be separated from the NMP waste liquid to the greatest extent, improving the purity of NMP extraction.

[0028] It should be noted that the more dehydration tank components there are, the higher the cost and the larger the area they occupy. Considering both cost and space requirements, two dehydration tank components are generally configured (i.e., Figure 1 (In the configuration), the first dehydration tank assembly removes most of the water from the NMP waste liquid, and the second dehydration tank 1 further removes water from the NMP waste liquid.

[0029] In some embodiments, the dehydration tank assembly may include at least a dehydration tank 1, a first reflux condenser, and a first reboiler 9. The dehydration tank 1 has an inlet JL1 for receiving NMP waste liquid. The low-temperature end of the dehydration tank 1 has outlets CS1, CS2, and HS1. The inlet JS1 of the first reflux condenser is connected to outlet CS2, the outlet CS3 is connected to HS1, and the outlet CS4 is externally connected to the NMP waste liquid storage tank 2. Outlet CS1 is used to output water separated during the dehydration process that did not enter the first reflux condenser. The high-temperature end of the dehydration tank 1 has outlets CL1, CL2, and HL1. The first reboiler 9 is installed between outlet CL2 and HL1, and outlet CL1 is used to output the dehydrated NMP waste liquid.

[0030] by Figure 1Taking the first dehydration tank assembly as an example, the outlet of the NMP absorption tower 3 is connected to the inlet of the NMP waste liquid storage tank 2. When the NMP waste liquid concentration at the bottom of the absorption tower increases to 85%, the NMP waste liquid will be transferred to the NMP waste liquid storage tank 2. Further, the NMP waste liquid is sent from the NMP waste liquid storage tank 2 to the dehydration tank 1 (i.e., sent to the dehydration tank 1 through the inlet JL1). The bottom temperature of the dehydration tank 1 is 125℃-135℃ (high temperature end), the top temperature is 105-115℃ (low temperature end), and the tank pressure is 5-7 kPa. The NMP waste liquid undergoes dehydration... In water tank 1, most of the water will be separated out. One part of the separated water will flow out through outlet CS1, and the other part of the separated water will enter the first condensation reflux device for condensation through outlet CS2. Part of the condensed water will flow back to dehydration tank 1 through return water outlet HS1, and the other part of the condensed water will be sent to NMP waste liquid storage tank 2. The waste liquid at the bottom of dehydration tank 1 mainly consists of a small amount of water, NMP and heavy metal components. Part of the waste liquid is heated by the first reboiler 9 and returned to dehydration tank 1, and the rest is sent to the second dehydration tank assembly.

[0031] The second dehydration tank assembly in the figure is similar to the one described above. The only difference is that the input NMP waste liquid is the waste liquid after one dehydration, and after a second dehydration, it is directly input into the refining tank assembly.

[0032] The components in the aforementioned dehydration tank assembly are all miniaturized, making them easy to integrate. This reduces the overall power consumption of the NMP purification unit while also reducing its size and installation and transportation costs.

[0033] It should be noted that the water flowing out of outlet CS1 can be collected separately through the tank. However, in some embodiments, outlet CS1 is connected to the NMP absorption tower 3, specifically to the inlet of the spray nozzle of the NMP absorption tower 3. Since NMP inevitably exists in the separated water, except for the condensed water, the remaining water is introduced into the NMP absorption tower 3 to avoid NMP waste. Moreover, the introduced water can also be used as spray water for the NMP absorption tower 3, reducing costs (spray water cost).

[0034] It should be noted that, in order to control the separation efficiency of the dehydration tank 1, in some embodiments, a first reflux pump 8 is installed between the outlet CS3 and the return outlet HS1. The reflux flow rate is controlled by the first reflux pump 8, thereby controlling the separation efficiency of the dehydration tank 1.

[0035] The aforementioned first condensation reflux device mainly includes a first condenser 4 and a first reflux tank 5 connected in sequence. The inlet JS1 is the inlet of the first condenser 4, which is used to condense the separated water. The outlets CS3 and CS4 are both outlets of the first reflux tank 5, which is used to collect the condensed water. The exhaust port of the first reflux tank 5 is connected in sequence to a first vacuum tank 6 and a first vacuum pump 7. The first vacuum tank 6 and the first vacuum pump 7 maintain the first reflux tank 5 under negative pressure, thereby lowering the boiling point of the material.

[0036] In some embodiments, the refining tank assembly includes a refining tank 10, a second reflux condenser, and a second reboiler 16. The refining tank 10 has an inlet JL2 for receiving dehydrated NMP waste liquid. The low-temperature end of the refining tank 10 is provided with outlets CY1 and CY2 and a return outlet HY1. The inlet JY1 of the second reflux condenser is connected to outlet CY2, and the outlet CY3 of the second reflux condenser is connected to return outlet HY1. Outlet CY1 is used to output the NMP purified liquid that did not enter the second reflux condenser. The high-temperature end of the refining tank 10 is provided with outlets CL3 and CL4 and a return outlet HL2. The second reboiler 16 is located between outlet CL4 and return outlet HL2. Outlet CL3 is used to output the separated heavy metal components.

[0037] Figure 1 In the process, the NMP waste liquid after secondary dehydration enters the refining tank 10 through the feed port JL2. The bottom temperature of the refining tank 10 is 145℃-155℃, i.e., the high temperature end, and the top temperature is 125-135℃, i.e., the low temperature end. The tank pressure is 5-7kPa. In the refining tank 10, NMP in the NMP waste liquid after secondary dehydration will be separated from the top of the tank. A portion of the separated NMP enters the second condensation reflux device through the liquid outlet CY2 for condensation. The condensed NMP flows back to the refining tank 10 through the liquid return port HY1. The other portion of separated NMP will be cooled sequentially through the liquid outlet CY1 and the NMP cooler and then sent to the finished product tank. The waste liquid at the bottom of the refining tank 10 consists of heavy metal components and a small amount of NMP (it is impossible to completely separate them, and a small amount of NMP will be retained). A portion of the waste liquid is heated by the second reboiler 16 and then returned to the refining tank 10. The remaining portion will be periodically discharged and processed through the discharge port CL3.

[0038] The components in the above-mentioned refining tank assembly are all miniaturized, which facilitates integration. This reduces the overall power consumption of the NMP purification unit, while also reducing its size and installation and transportation costs.

[0039] It should be noted that, in order to control the separation efficiency of the refining tank 10, in some embodiments, a second reflux pump 15 is installed between the liquid outlet CY3 and the liquid return port HY1. The reflux flow rate is controlled by the second reflux pump 15, thereby controlling the separation efficiency of the refining tank 10.

[0040] The structure of the second condensation reflux device is similar to that of the first condensation reflux device. It mainly includes a second condenser 11 and a second reflux tank 12 connected in sequence. The liquid inlet JY1 is the liquid inlet of the second condenser 11, and the liquid outlet CY3 is the liquid outlet of the second reflux tank 12. The air extraction port of the second reflux tank 12 is connected in sequence to a second vacuum tank 13 and a second vacuum pump 14. The second vacuum tank 13 and the second vacuum pump 14 keep the second reflux tank 12 under negative pressure, thereby reducing the boiling point of the material.

[0041] It should be noted that the liquid in the NMP purification unit can be pumped by the power pump 17, such as the pumping between the NMP absorption tower 3 and the NMP waste liquid storage tank 2, the pumping between the NMP waste liquid storage tank 2 and the dehydration tank 1, the pumping between the dehydration tanks 1 and 1, the pumping between the dehydration tank 1 and the purification tank 10, and the pumping at the discharge port CL3, etc.

[0042] It should be noted that some sensors and control terminals can be configured on the basis of the above-mentioned NMP purification device to realize automatic control of the NMP purification device. For example, if a sensor is built into the MP absorption tower, when the concentration of NMP waste liquid at the bottom is detected to rise to 85%, the control terminal will control the power pump between the NMP absorption tower 3 and the NMP waste liquid storage tank 2 to work.

[0043] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. An NMP purification apparatus, characterized in that, It includes a dehydration tank assembly and a refining tank assembly; the dehydration tank assembly dehydrates the NMP waste liquid, and the refining tank assembly separates the heavy metal components from the dehydrated NMP waste liquid and outputs the purified NMP solution.

2. The apparatus according to claim 1, characterized in that, The dehydration tank assembly is provided in multiple ways, and the multiple dehydration tank assemblies and refining tank assemblies are connected in series. The first dehydration tank assembly is externally connected to an NMP waste liquid storage tank.

3. The apparatus according to claim 1 or 2, characterized in that, The dehydration tank assembly includes a dehydration tank, a first condenser reflux device, and a first reboiler; The feed inlet JL1 of the dehydration tank is used to input NMP waste liquid. The low-temperature end of the dehydration tank is equipped with outlet CS1, outlet CS2 and return water inlet HS1. The inlet JS1 of the first condensation reflux device is connected to outlet CS2. The outlet CS3 of the first condensation reflux device is connected to return water inlet HS1. The outlet CS4 of the first condensation reflux device is externally connected to the NMP waste liquid storage tank. The outlet CS1 is used to output the water that was separated during the dehydration process but did not enter the first condensation reflux device. The high-temperature end of the dehydration tank is equipped with discharge port CL1, discharge port CL2 and return port HL1. The first reboiler is located between discharge port CL2 and return port HL1. Discharge port CL1 is used to output the NMP waste liquid after dehydration treatment.

4. The apparatus according to claim 3, characterized in that, The outlet CS1 is connected to the NMP absorption tower; the outlet of the NMP absorption tower is connected to the inlet of the NMP waste liquid storage tank.

5. The apparatus according to claim 3, characterized in that, A first reflux pump is installed between the outlet CS3 and the return outlet HS1.

6. The apparatus according to claim 3, characterized in that, The first condensation reflux device includes a first condenser and a first reflux tank connected in sequence. The inlet JS1 is the inlet of the first condenser, and the outlets CS3 and CS4 are the outlets of the first reflux tank. The evacuation port of the first reflux tank is connected in sequence to a first vacuum tank and a first vacuum pump.

7. The apparatus according to claim 1 or 2, characterized in that, The refining tank assembly includes a refining tank, a second reflux condenser, and a second reboiler; The feed inlet JL2 of the refining tank is used to input the dehydrated NMP waste liquid. The low-temperature end of the refining tank is equipped with a liquid outlet CY1, a liquid outlet CY2 and a liquid return port HY1. The liquid inlet JY1 of the second condensation reflux device is connected to the liquid outlet CY2. The liquid outlet CY3 of the second condensation reflux device is connected to the liquid return port HY1. The liquid outlet CY1 is used to output the NMP purified liquid that did not enter the second condensation reflux device. The high-temperature end of the refining tank is equipped with discharge port CL3, discharge port CL4 and return port HL2. The second reboiler is located between discharge port CL4 and return port HL2. Discharge port CL3 is used to output the separated heavy metal components.

8. The apparatus according to claim 7, characterized in that, A second reflux pump is installed between the liquid outlet CY3 and the liquid return outlet HY1.

9. The apparatus according to claim 7, characterized in that, The second condensation reflux device includes a second condenser and a second reflux tank connected in sequence. The liquid inlet JY1 is the liquid inlet of the second condenser, and the liquid outlet CY3 is the liquid outlet of the second reflux tank. The vacuum port of the second reflux tank is connected in sequence to a second vacuum tank and a second vacuum pump.

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