Reaction gas recycling device and lithium hexafluorophosphate preparation system

Abstract

The application discloses a reaction gas recycling device, which comprises a low-pressure buffer tank, a separator, a booster, a condenser and a high-pressure buffer tank. The low-pressure buffer tank is used for collecting low-pressure tail gas; the separator is used for removing liquid in the tail gas and forming dry gas; the booster is used for pressurizing the dry gas to form high-pressure gas; the condenser is used for condensing the high-pressure gas; and the high-pressure buffer tank is used for storing the high-pressure gas. By using the reaction gas recycling device, the separator removes liquid in the tail gas to form dry gas, the dry gas is pressurized by the booster to form high-pressure gas, the boiling point temperature of the pressurized gas is lowered, the gas impurities with higher boiling point temperature are removed by the condenser, and then the high-pressure PF5 reaction gas is collected by the high-pressure buffer tank, so that the organic solvent washing and adsorption are not needed, the process is simplified, and the treatment process of the organic solvent is not needed to be increased. The application further discloses a lithium hexafluorophosphate preparation system.

Description

Technical Field

[0001] This application belongs to the field of gas recovery technology, specifically relating to a reaction gas recovery and utilization device and a lithium hexafluorophosphate preparation system. Background Technology

[0002] The preparation of lithium hexafluorophosphate requires a continuous gas-liquid reaction, such as reacting PF5 (phosphorus pentafluoride) with a hydrogen fluoride solution of LiF (lithium fluoride) and then directly crystallizing to obtain lithium hexafluorophosphate crystals. However, in the continuous gas-liquid reaction, the exhaust gas contains unreacted PF5 reaction gas, and the PF5 reaction gas may also contain liquid entrainment.

[0003] Currently, the recovery of PF5 from exhaust gas typically involves washing with organic solvents (such as carbon tetrachloride or benzene), followed by heating and desorption of the resulting washing liquid. The desorbed gaseous substances are then condensed and purified to obtain PF5. However, this recovery method introduces organic solvents, which require subsequent treatment, making the process overly complex. Utility Model Content

[0004] The technical problem to be solved by this application is that the existing process for PF5 recovery from exhaust gas is too complicated. In order to solve this technical problem, a reaction gas recovery device and a lithium hexafluorophosphate preparation system that do not introduce other organic solvents and simplify the process are provided.

[0005] The technical solution proposed in this application is as follows:

[0006] A reaction gas recovery and utilization device, comprising:

[0007] Low-pressure buffer tank, used to collect exhaust gas;

[0008] A separator, located downstream of the low-pressure buffer tank, is used to remove liquid from the exhaust gas and form dry gas.

[0009] A booster compressor, located downstream of the separator, is used to pressurize the dry gas to form a high-pressure gas.

[0010] A condenser, located downstream of the booster, is used to condense high-pressure gas.

[0011] A high-pressure buffer tank, located downstream of the condenser, is used to store high-pressure gas.

[0012] Using the aforementioned reaction gas recovery and utilization device, a low-pressure buffer tank collects low-pressure tail gas, a separator removes liquid from the tail gas to form dry gas, and the dry gas is pressurized by a booster to form high-pressure gas. After pressurization, the boiling point temperature of the gas decreases, and a condenser removes gaseous impurities with higher boiling points. Then, the high-pressure PF5 reaction gas is collected in the high-pressure buffer tank. Thus, there is no need for organic solvent washing and adsorption, thereby eliminating the need for subsequent organic solvent treatment steps, simplifying the process, and reducing costs.

[0013] Furthermore, it also includes two condensing jackets, which are respectively disposed on the outside of the low-pressure buffer tank and the high-pressure buffer tank.

[0014] Furthermore, both the gas phase outlet and the liquid phase outlet of the condenser are connected to the high-pressure buffer tank.

[0015] Furthermore, both the bottom of the low-pressure buffer tank and the bottom of the high-pressure buffer tank are provided with drain ports, and drain valves are provided at the drain ports.

[0016] Furthermore, it also includes a liquid recovery mechanism, which is connected to the drain valve at the low-pressure buffer tank and the high-pressure buffer tank.

[0017] Furthermore, it also includes a condensing mechanism, which is connected to the condenser and the condensing jacket, for providing refrigerant.

[0018] Furthermore, it also includes a gas replenishment component connected to the high-pressure buffer tank and the low-pressure buffer tank, and the gas replenishment component is configured to connect or disconnect the high-pressure buffer tank and the low-pressure buffer tank.

[0019] Furthermore, it also includes a pressure relief assembly connected to the low-pressure buffer tank and the high-pressure buffer tank.

[0020] Furthermore, the separator is a demister, and the booster is a diaphragm compressor.

[0021] A lithium hexafluorophosphate preparation system includes a reaction gas recovery and utilization device as described above. Attached Figure Description

[0022] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0023] Figure 1 This is a schematic diagram of the structure of a reaction gas recovery and utilization device provided in an embodiment of this application.

[0024] Label Explanation:

[0025] 11. Low-pressure buffer tank; 12. Separator; 121. Flushing mechanism; 13. Booster; 14. Condenser; 15. High-pressure buffer tank; 16. Condensing jacket; 17. Condensing mechanism; 18. Liquid recovery mechanism; 19. Gas supply assembly; 20. Pressure relief assembly; 21. Gas recovery mechanism. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0028] On the one hand, this application provides a reaction gas recovery and utilization device, which can collect the tail gas generated during the preparation of lithium hexafluorophosphate and recover and reuse the PF5 reaction gas in the tail gas.

[0029] like Figure 1 As shown, the reaction gas recovery and utilization device includes a low-pressure buffer tank 11, a separator 12, a booster 13, a condenser 14, and a high-pressure buffer tank 15.

[0030] A low-pressure buffer tank 11 receives low-pressure exhaust gas, which includes PF5 reactant gas, AHF (anhydrous hydrogen fluoride, assumed to be gaseous unless otherwise specified), and some liquid (e.g., liquid AHF and lithium hexafluorophosphate solution). A separator 12, located downstream of the low-pressure buffer tank 11, receives the exhaust gas and performs gas-liquid separation to remove liquid and form dry gas. A booster compressor 13, located downstream of the separator 12, receives the dry gas and pressurizes it to form high-pressure gas. A condenser 14, located downstream of the booster compressor 13, condenses the high-pressure gas to remove some gaseous impurities, such as AHF. A high-pressure buffer tank 15, located downstream of the condenser 14, stores the high-pressure gas after impurity removal. Optionally, the separator 12 is a demister, and the booster compressor 13 is a diaphragm compressor.

[0031] In the preparation of lithium hexafluorophosphate, the PF5 reactant gas is stored in a raw material gas tank at a relatively high pressure to continuously supply the PF5 reactant gas into the hydrogen fluoride solution. If the existing tail gas is directly purified and then introduced into the raw material gas tank, it will cause gas leakage and pressure drop in the raw material gas tank, thereby affecting the gas supply to the raw material gas tank.

[0032] Using the above-described reaction gas recovery and utilization device, the low-pressure buffer tank 11 collects the low-pressure tail gas, the separator 12 removes the liquid from the tail gas to form dry gas, and the dry gas is pressurized by the booster 13 to form high-pressure gas, according to the Clausius-Clapeyron equation:

[0033]

[0034] Where: P is pressure, T is boiling point temperature, and ΔH is... vap R is the heat of vaporization (positive value) and R is the gas constant.

[0035] It is known that when the gas pressure increases, P2>P1, therefore T2>T1, meaning that an increase in pressure inevitably leads to an increase in boiling point. Therefore, the change in boiling point temperature of two or more gases under different gas pressures can be utilized to separate the two gases into gas and liquid phases via condenser 14, thereby removing gaseous impurities. The high-pressure reactant gas is then collected in high-pressure buffer tank 15. Thus, there is no need for washing and adsorption with organic solvents, eliminating the need for subsequent organic solvent treatment steps, simplifying the process, and reducing costs.

[0036] In one embodiment, the reaction gas recovery and utilization device further includes a condensing jacket 16, which is disposed outside the low-pressure buffer tank 11 to cool the low-pressure buffer tank 11 so that the liquid in the exhaust gas is kept in a liquid state as much as possible, avoiding excessive pressure fluctuations caused by excessive vaporization of the liquid. At the same time, it can also ensure that after the exhaust gas enters the separator 12, the separator 12 can separate the liquid and gas in the exhaust gas.

[0037] Furthermore, the reaction gas recovery and utilization device includes two condensing jackets 16, one of which is located outside the low-pressure buffer tank 11, and the other is located outside the high-pressure buffer tank 15. Similarly, the condensing jacket 16 located outside the high-pressure buffer tank 15 is used to cool the high-pressure buffer tank 15, so that the AHF entering the high-pressure buffer tank 15 remains in a liquid state, preventing it from turning into a gaseous state and mixing with the PF5 reaction gas before being output to the feed gas tank.

[0038] It should be noted that both the gas phase outlet and the liquid phase outlet of the condenser 14 are connected to the high-pressure buffer tank 15, thus allowing both high-pressure gas and condensate to be input into the high-pressure buffer tank 15. Specifically, as follows... Figure 1 As shown, the gas phase outlet and liquid phase outlet of the condenser 14 are the same outlet and are connected to the high-pressure buffer tank 15. At the same time, the high-pressure buffer tank 15 is connected to the raw material gas tank through an exhaust pipe, and in order to ensure the separation of condensate and high-pressure gas, the exhaust pipe is connected to the top of the high-pressure buffer tank 15.

[0039] In one embodiment, the reaction gas recovery and utilization device includes a condensing mechanism 17, which is connected to a condenser 14 and a condensing jacket 16, for providing a refrigerant to cool and condense the gas by the refrigerant flowing within the condenser 14 and the condensing jacket 16.

[0040] In this embodiment, the temperatures of the refrigerant in the two condensing jackets 16 and the condenser 14 can be the same.

[0041] It should be explained that most of the AHF in the exhaust gas is gaseous, with a small portion being liquid. To avoid excessive pressure fluctuations, the condensing jacket 16 generally does not condense the temperature inside the low-pressure buffer tank 11 to a level far below the boiling point of AHF, thus preventing a large amount of gaseous AHF from condensing into liquid. Furthermore, the exhaust gas does not remain in the low-pressure buffer tank 11 for an exceptionally long time, thus preventing both the large-scale vaporization of liquid AHF and the condensation of large amounts of gaseous AHF into liquid.

[0042] Specifically, in this embodiment, the pressure of the exhaust gas is 0.05~0.1MPa, and the pressure of the high-pressure gas obtained after pressurization is 0.3~0.6MPa. For example, the low pressure is atmospheric pressure (0.1MPa), the boiling point temperature of the PF5 reactant gas in the exhaust gas is -84.6℃, and the boiling point temperature of AHF is 19.54℃; based on experimental measurements, the boiling point temperature range of the PF5 reactant gas in the high-pressure gas (gas pressure 0.3~0.6MPa) is -54.74℃~-39.3℃, and the boiling point temperature range of AHF is 63℃~84℃.

[0043] Therefore, the refrigerant temperature can be set below 19.54℃ and above -84.6℃, preferably 0~-20℃, for example -5℃. In a low-pressure environment, the refrigerant temperature is slightly lower than the boiling point of AHF, but the temperature difference is small, which can prevent a large amount of AHF in the exhaust gas from liquefying, affecting the gas-liquid separation effect, while ensuring gas flow. After being pressurized by the booster, the exhaust gas pressure increases, based on the fact that AHF forms polymers (such as (HF)) due to hydrogen bonding in its liquid state. n This results in a higher heat of vaporization than that of ordinary nonpolar gases, making its boiling point more sensitive to pressure changes (the boiling point rises more significantly under the same pressure increase). Under the same refrigerant cooling effect, it can liquefy a large amount of gaseous AHF, thereby achieving the purpose of separating PF5 and AHF in the exhaust gas without solvent.

[0044] In one embodiment, the reactive gas recovery and utilization device further includes a flushing mechanism 121, which is connected to the separator 12 and is used to deliver liquid AHF to the separator 12 to flush the separator 12 and prevent it from becoming clogged. In practical applications, the top of the separator 12 is provided with a flushing port, and the flushing mechanism 121 is connected to the flushing port.

[0045] In one embodiment, both the bottom of the low-pressure buffer tank 11 and the bottom of the high-pressure buffer tank 15 are provided with drain ports to discharge condensate. Furthermore, both the drain ports of the low-pressure buffer tank 11 and the high-pressure buffer tank 15 are provided with drain valves to control the discharge of condensate.

[0046] Furthermore, the reaction gas recovery and utilization device also includes a liquid recovery mechanism 18, which is connected to the drain valve at the low-pressure buffer tank 11 and the drain valve at the high-pressure buffer tank 15 to recover liquid AHF and reduce material loss.

[0047] In one embodiment, the reaction gas recovery and utilization device further includes a gas replenishment component 19, which is connected to the high-pressure buffer tank 15 and the low-pressure buffer tank 11. The gas replenishment component 19 is configured to either connect or disconnect the high-pressure buffer tank 15 and the low-pressure buffer tank 11. Thus, when the gas pressure in the low-pressure buffer tank 11 is too low, the gas replenishment component 19 can connect the high-pressure buffer tank 15 and the low-pressure buffer tank 11, allowing gas from the high-pressure buffer tank 15 to be introduced into the low-pressure buffer tank 11. Alternatively, when the gas pressure in the high-pressure buffer tank 15 is too high, the gas replenishment component 19 can connect the high-pressure buffer tank 15 and the low-pressure buffer tank 11 to depressurize the high-pressure buffer tank 15.

[0048] It should be explained that the low-pressure buffer tank 11 receives the exhaust gas produced by the reaction, and the gas in the low-pressure buffer tank 11 is transported to the downstream separator 12, booster 13, etc. If the exhaust gas input is low, the gas pressure in the low-pressure buffer tank 11 will drop to a certain level, which will affect the operation of the booster 13. Therefore, when the gas pressure in the low-pressure buffer tank 11 is too low, the high-pressure buffer tank 15 and the low-pressure buffer tank 11 are connected through the gas replenishment component 19, and the gas in the high-pressure buffer tank 15 is introduced into the low-pressure buffer tank 11.

[0049] In one embodiment, the reaction gas recovery device further includes a pressure relief assembly 20, which is connected to the low-pressure buffer tank 11 and the high-pressure buffer tank 15, and is used to relieve pressure when the pressure in the low-pressure buffer tank 11 and the high-pressure buffer tank 15 is too high.

[0050] In one embodiment, the reaction gas recovery device further includes a gas recovery mechanism 21, which is connected to the high-pressure buffer tank 15 and is used to collect PF5 reaction gas, thereby realizing the recovery and utilization of PF5 reaction gas. In practical applications, the gas recovery mechanism 21 includes an exhaust pipe and a raw material gas tank, and the high-pressure buffer tank 15 is connected to the raw material gas tank through the exhaust pipe.

[0051] To facilitate understanding of the technical solution of this application, this document combines... Figure 1 The process flow of the reaction gas recovery and utilization device in the above embodiments is described as follows:

[0052] The exhaust gas is piped into the low-pressure buffer tank 11. Upon passing through the separator 12, the gas and liquid are separated, forming a dry gas. This dry gas is then pressurized by the booster 13 to form a high-pressure gas, which subsequently enters the condenser 14. The condenser 14 condenses the AHF in the high-pressure gas into a liquid state. The liquid AHF and the high-pressure gas (i.e., the PF5 reactant gas) then enter the high-pressure buffer tank 15. The liquid AHF in the high-pressure buffer tank 15 can be discharged to the liquid recovery mechanism 18 through the drain port, while the high-pressure gas can be transported to the raw material gas tank through the exhaust pipe, thus achieving the recovery and reuse of the PF5 reactant gas.

[0053] On the other hand, based on the above-mentioned reaction gas recovery and utilization device, this application also provides a lithium hexafluorophosphate preparation system, which includes the reaction gas recovery and utilization device in the above embodiments.

[0054] In summary, the reaction gas recovery and utilization device and the lithium hexafluorophosphate preparation system provided in this application have at least the following advantages:

[0055] 1. There is no need to use organic solvents to wash and adsorb the PF5 reaction gas in the tail gas, thus eliminating the need for an organic solvent treatment process, simplifying the process and reducing costs;

[0056] 2. The PF5 reaction gas after impurity removal is a high-pressure gas, which can be directly input into the raw material gas tank without causing gas leakage from the raw material gas tank;

[0057] 3. The AHF liquid generated by condensation can also be recovered through the liquid recovery mechanism 18, further reducing material loss and lowering costs;

[0058] 4. A condensing jacket 16 is installed on the outside of the low-pressure buffer tank 11, and a separator 12 is installed downstream. This can effectively separate gas and liquid, and prevent liquid from entering the booster 13 and affecting the operation of the booster 13.

[0059] 5. A condensing jacket 16 is installed on the outside of the high-pressure buffer tank 15 to ensure that the AHF input into the high-pressure buffer tank 15 remains in a liquid state, thereby achieving the separation of AHF and PF5 reaction gas.

[0060] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for recovering and utilizing reactive gases, characterized in that, include: Low-pressure buffer tank, used to collect exhaust gas; A separator, located downstream of the low-pressure buffer tank, is used to remove liquid from the exhaust gas and form dry gas. A booster compressor, located downstream of the separator, is used to pressurize the dry gas to form a high-pressure gas. A condenser, located downstream of the booster, is used to condense high-pressure gas. A high-pressure buffer tank, located downstream of the condenser, is used to store high-pressure gas.

2. The reaction gas recovery and utilization device according to claim 1, characterized in that, It also includes two condensing jackets, which are respectively disposed on the outside of the low-pressure buffer tank and the high-pressure buffer tank.

3. The reaction gas recovery and utilization device according to claim 2, characterized in that, Both the gas phase outlet and the liquid phase outlet of the condenser are connected to the high-pressure buffer tank.

4. The reaction gas recovery and utilization device according to claim 2, characterized in that, Both the bottom of the low-pressure buffer tank and the bottom of the high-pressure buffer tank have drain ports, and drain valves are provided at the drain ports.

5. The reaction gas recovery and utilization device according to claim 4, characterized in that, It also includes a liquid recovery mechanism, which is connected to the drain valves of the low-pressure buffer tank and the high-pressure buffer tank.

6. The reaction gas recovery and utilization device according to claim 2, characterized in that, It also includes a condensing mechanism, which is connected to the condenser and the condensing jacket, and is used to provide refrigerant.

7. The reaction gas recovery and utilization device according to claim 1, characterized in that, It also includes a gas replenishment component, which is connected to the high-pressure buffer tank and the low-pressure buffer tank, and is configured to connect or disconnect the high-pressure buffer tank and the low-pressure buffer tank.

8. The reaction gas recovery and utilization device according to claim 1, characterized in that, It also includes a pressure relief assembly, which is connected to the low-pressure buffer tank and the high-pressure buffer tank.

9. The reaction gas recovery and utilization device according to claim 1, characterized in that, The separator is a demister, and the booster is a diaphragm compressor.

10. A lithium hexafluorophosphate preparation system, characterized in that, Includes the reaction gas recovery and utilization device according to any one of claims 1-9.

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