Lithium hexafluorophosphate production tail gas treatment system

Abstract

The utility model relates to a lithium hexafluorophosphate production tail gas treatment system. The lithium hexafluorophosphate production tail gas treatment system comprises a first condensing tower, a hydrogen fluoride storage tank, a first compressor, a second condensing tower, a phosphorus pentafluoride storage tank, an absorption tower, an absorption liquid storage tank and a booster pump. A gas inlet of the first condensing tower is connected with a gas outlet of the synthesis kettle through a first connecting pipe, a liquid outlet of the first condensing tower is connected with a liquid inlet of the hydrogen fluoride storage tank through a second connecting pipe, and a gas outlet of the first condensing tower is connected with a gas inlet of the second compressor through a third connecting pipe; a gas inlet of the second condensing tower is connected with a gas outlet of the first compressor through a fourth connecting pipe, a liquid outlet of the second condensing tower is connected with a liquid inlet of the phosphorus pentafluoride storage tank through a fifth connecting pipe, and a gas outlet of the second condensing tower is connected with a gas inlet of the drying system. According to the lithium hexafluorophosphate production tail gas treatment system, hydrogen fluoride and phosphorus pentafluoride can be recycled, and resource waste is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of tail gas treatment systems, and in particular relates to a tail gas treatment system for lithium hexafluorophosphate production. Background Art

[0002] Lithium hexafluorophosphate (LFP), the most widely commercialized lithium-ion battery electrolyte, possesses excellent ionic conductivity and electrochemical stability, making it a core raw material for its production. With the rapid development of the new energy industry, market demand for LFP is rapidly increasing, and the industry has a promising future.

[0003] Currently, lithium hexafluorophosphate (LFP) production primarily utilizes a hydrogen fluoride solvent process. The tail gas generated during the production process primarily consists of large amounts of hydrogen chloride gas, nitrogen as a protective gas, and small amounts of unreacted hydrogen fluoride and phosphorus pentafluoride gas. The commonly used tail gas treatment method in production involves first condensing the majority of the hydrogen fluoride gas, then using a packing material to absorb the tail gas to remove the hydrogen chloride and phosphorus pentafluoride, which are difficult to condense under normal pressure. This produces fluorine-containing dilute hydrochloric acid as a by-product. However, the phosphorus pentafluoride is not effectively recovered, but instead is absorbed into the tail gas and dissolved in the fluorine-containing dilute hydrochloric acid. This not only wastes fluorine and phosphorus resources, but also hinders the reuse of the fluorine-containing dilute hydrochloric acid. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a tail gas treatment system for lithium hexafluorophosphate production.

[0005] The technical solution of a lithium hexafluorophosphate production tail gas treatment system of the utility model is:

[0006] A lithium hexafluorophosphate production tail gas treatment system includes a first condensing tower, a hydrogen fluoride storage tank, a first compressor, a second condensing tower, a phosphorus pentafluoride storage tank, an absorption tower, an absorption liquid storage tank, and a booster pump;

[0007] The air inlet of the first condensation tower is connected to the air outlet of the synthesis kettle through a first connecting pipe, the liquid outlet of the first condensation tower is connected to the liquid inlet of the hydrogen fluoride storage tank through a second connecting pipe, the air outlet of the first condensation tower is connected to the air inlet of the second compressor through a third connecting pipe, the air inlet of the second condensation tower is connected to the air outlet of the first compressor through a fourth connecting pipe, the liquid outlet of the second condensation tower is connected to the liquid inlet of the phosphorus pentafluoride storage tank through a fifth connecting pipe, the air outlet of the second condensation tower is connected to the air inlet of the drying system, the air inlet of the absorption tower is connected to the air outlet pipe of the drying system through a sixth connecting pipe, the liquid outlet of the absorption tower is connected to the liquid inlet of the absorption liquid storage tank through a seventh connecting pipe, the liquid inlet of the booster pump is connected to the liquid outlet pipe of the absorption liquid storage tank through an eighth connecting pipe, and the liquid outlet of the booster pump is connected to the spray pipe of the absorption tower through a ninth connecting pipe.

[0008] Furthermore, the lithium hexafluorophosphate production tail gas treatment system includes a second compressor and a third condensing tower, the air inlet of the second compressor is connected to the air outlet of the second condensing tower through a tenth connecting pipe, the air outlet of the second compressor is connected to the air inlet of the third condensing tower through an eleventh connecting pipe, the air outlet of the third condensing tower is connected to the air inlet of the drying system through a twelfth connecting pipe, and the liquid outlet of the third condensing tower is connected to the fifth connecting pipe through a thirteenth connecting pipe.

[0009] Furthermore, a cooling pipe is provided in the absorption liquid storage tank.

[0010] Furthermore, the cooling pipe is a coil, the cooling liquid inlet and the cooling liquid outlet of the cooling pipe respectively extend out of the outside of the absorption liquid storage tank, and the cooling liquid inlet of the cooling pipe is located at the lower side of the cooling liquid outlet.

[0011] Furthermore, the boost pump is located on the upper side of the coolant storage tank, and the lower end of the liquid outlet pipe of the coolant storage tank extends to the lower side of the coolant storage tank.

[0012] The utility model provides a lithium hexafluorophosphate production tail gas treatment system, which has the following beneficial effects compared with the prior art:

[0013] The utility model discloses a lithium hexafluorophosphate production tail gas treatment system. The tail gas is condensed and removed by a first condensation tower. After the hydrogen fluoride is removed, the mixed gas is compressed to increase the boiling point of phosphorus pentafluoride and hydrogen chloride. Then, the mixed gas is condensed and removed by a second condensation tower. The low-temperature tail gas whose main components are nitrogen and hydrogen chloride is recycled to the production drying system. Finally, the exhaust gas is removed by absorption liquid through the absorption tower to absorb hydrogen chloride and other trace pollutants so that the exhaust gas meets the prescribed emission standards. The low-temperature tail gas whose main components are nitrogen and hydrogen chloride can be recycled for the preliminary drying of lithium hexafluorophosphate semi-finished products. The acid content of the lithium hexafluorophosphate semi-finished products is relatively high in the early stage of drying. If the high-temperature nitrogen is directly used for drying, the material deacidification speed is too fast, which easily causes the material to caking, making it more difficult to separate the hydrofluoric acid contained in the agglomerated material, affecting the drying effect and reducing the product quality. The use of condensed low-temperature tail gas can solve this problem. Under the premise of not introducing foreign impurities, the drying efficiency is improved and the process energy consumption is reduced. By installing a cooling pipe within the coolant storage tank and connecting it to an external cooling unit, the cooling pipe can cool the heated absorption liquid, enhancing the absorption liquid's ability to absorb hydrogen chloride and maintaining a high absorption capacity for the entire system. The lithium hexafluorophosphate production tail gas treatment system of this invention can recycle hydrogen fluoride and phosphorus pentafluoride, avoiding resource waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of a tail gas treatment system for lithium hexafluorophosphate production according to the present invention;

[0015] In the figure: 1. synthesis reactor; 2. first connecting pipe; 3. first condensing tower; 4. second connecting pipe; 5. hydrogen fluoride storage tank; 6. first compressor; 7. third connecting pipe; 8. fourth connecting pipe; 9. second condensing tower; 10. second compressor; 11. third condensing tower; 12. fifth connecting pipe; 13. phosphorus pentafluoride storage tank; 14. drying system; 15. sixth connecting pipe; 16. absorption tower; 17. absorption liquid storage tank; 18. cooling pipe; 19. seventh connecting pipe; 20. booster pump; 21. eighth connecting pipe; 22. ninth connecting pipe; 23. tenth connecting pipe; 24. eleventh connecting pipe; 25. twelfth connecting pipe; 26. thirteenth connecting pipe. DETAILED DESCRIPTION

[0016] The present invention is described in further detail below with reference to the accompanying drawings and specific embodiments:

[0017] The specific embodiment of the lithium hexafluorophosphate production tail gas treatment system of the present utility model is as follows: Figure 1 As shown, it includes a first condensing tower 3, a hydrogen fluoride storage tank 5, a first compressor 6, a second condensing tower 9, a phosphorus pentafluoride storage tank 13, an absorption tower 16, an absorption liquid storage tank 17 and a booster pump 20.

[0018] The air inlet of the first condensing tower 3 is connected to the air outlet of the synthesis reactor 1 through the first connecting pipe 2, the liquid outlet of the first condensing tower 3 is connected to the liquid inlet of the hydrogen fluoride storage tank 5 through the second connecting pipe 4, the air outlet of the first condensing tower 3 is connected to the air inlet of the second compressor 10 through the third connecting pipe 7, the air inlet of the second condensing tower 9 is connected to the air outlet of the first compressor 6 through the fourth connecting pipe 8, and the liquid outlet of the second condensing tower 9 is connected to the inlet of the phosphorus pentafluoride storage tank 13 through the fifth connecting pipe 12. The air outlet of the second condensing tower 9 is connected to the air inlet of the drying system 14, the air inlet of the absorption tower 16 is connected to the air outlet pipe of the drying system 14 through the sixth connecting pipe 15, the liquid outlet of the absorption tower 16 is connected to the liquid inlet of the absorption liquid storage tank 17 through the seventh connecting pipe 19, the liquid inlet of the booster pump 20 is connected to the liquid outlet pipe of the absorption liquid storage tank 17 through the eighth connecting pipe 21, and the liquid outlet of the booster pump 20 is connected to the spray pipe of the absorption tower 16 through the ninth connecting pipe 22.

[0019] The lithium hexafluorophosphate production tail gas treatment system includes a second compressor 10 and a third condensing tower 11. The air inlet of the second compressor 10 is connected to the air outlet of the second condensing tower 9 through the tenth connecting pipe 23, the air outlet of the second compressor 10 is connected to the air inlet of the third condensing tower 11 through the eleventh connecting pipe 24, the air outlet of the third condensing tower 11 is connected to the air inlet of the drying system 14 through the twelfth connecting pipe 25, and the liquid outlet of the third condensing tower 11 is connected to the fifth connecting pipe 12 through the thirteenth connecting pipe 26.

[0020] The cooling pipe 18 is a coil pipe, the cooling liquid inlet and the cooling liquid outlet of the cooling pipe 18 extend outside the absorption liquid storage tank 17, the cooling liquid inlet of the cooling pipe 18 is located at the lower side of the cooling liquid outlet.

[0021] The lithium hexafluorophosphate production tail gas treatment system of the utility model through first condensing tower 3, condense and remove hydrogen fluoride, the mixed gas after removing hydrogen fluoride is compressed, the boiling point of phosphorus pentafluoride and hydrogen chloride is raised, then through second condensing tower 9, condense and remove phosphorus pentafluoride, the low-temperature tail gas with main component being nitrogen and hydrogen chloride is reused to the drying system 14 of production, finally uses the absorption liquid to pass through the absorption tower 16 and absorbs and removes hydrogen chloride and other trace contaminating gas, and the method makes waste gas reach the prescribed discharge standard. The low-temperature tail gas with main component being nitrogen and hydrogen chloride can be recycled and used for the preliminary drying of lithium hexafluorophosphate semi-finished product, the lithium hexafluorophosphate semi-finished product has higher acid content in the early stage of drying, if directly using high-temperature nitrogen to dry, then the material deacidification speed is too fast, and it is easy to cause the material to be hardened, makes the hydrogen fluoride wrapped in the caked material more difficult to separate, influences the drying effect, and reduces product quality. Using the low-temperature tail gas after condensation can solve this problem, under the premise of not introducing foreign impurities, improves the drying efficiency, and reduces process energy consumption. By setting the cooling pipe 18 in the cooling liquid storage tank, the cooling pipe 18 is connected with an external cooling unit, the cooling pipe 18 can cool the absorption liquid with temperature rising, enhances the absorption effect of the absorption liquid on hydrogen chloride, and makes the whole system maintain higher absorption capacity. The lithium hexafluorophosphate production tail gas treatment system of the utility model can recycle hydrogen fluoride and phosphorus pentafluoride, and avoids resource waste.

[0022] The above is only the preferred embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A tail gas treatment system for lithium hexafluorophosphate production, characterized in that: It includes a first condensing tower, a hydrogen fluoride storage tank, a first compressor, a second condensing tower, a phosphorus pentafluoride storage tank, an absorption tower, an absorption liquid storage tank and a booster pump; The air inlet of the first condensation tower is connected to the air outlet of the synthesis kettle through a first connecting pipe, the liquid outlet of the first condensation tower is connected to the liquid inlet of the hydrogen fluoride storage tank through a second connecting pipe, the air outlet of the first condensation tower is connected to the air inlet of the second compressor through a third connecting pipe, the air inlet of the second condensation tower is connected to the air outlet of the first compressor through a fourth connecting pipe, the liquid outlet of the second condensation tower is connected to the liquid inlet of the phosphorus pentafluoride storage tank through a fifth connecting pipe, the air outlet of the second condensation tower is connected to the air inlet of the drying system, the air inlet of the absorption tower is connected to the air outlet pipe of the drying system through a sixth connecting pipe, the liquid outlet of the absorption tower is connected to the liquid inlet of the absorption liquid storage tank through a seventh connecting pipe, the liquid inlet of the booster pump is connected to the liquid outlet pipe of the absorption liquid storage tank through an eighth connecting pipe, and the liquid outlet of the booster pump is connected to the spray pipe of the absorption tower through a ninth connecting pipe.

2. The lithium hexafluorophosphate production tail gas treatment system according to claim 1, characterized in that: The lithium hexafluorophosphate production tail gas treatment system includes a second compressor and a third condensing tower, the air inlet of the second compressor is connected to the air outlet of the second condensing tower through a tenth connecting pipe, the air outlet of the second compressor is connected to the air inlet of the third condensing tower through an eleventh connecting pipe, the air outlet of the third condensing tower is connected to the air inlet of the drying system through a twelfth connecting pipe, and the liquid outlet of the third condensing tower is connected to the fifth connecting pipe through a thirteenth connecting pipe.

3. The lithium hexafluorophosphate production tail gas treatment system according to claim 1, characterized in that: A cooling pipe is provided in the absorption liquid storage tank.

4. The lithium hexafluorophosphate production tail gas treatment system according to claim 3, characterized in that: The cooling pipe is a coil, and the cooling liquid inlet and the cooling liquid outlet of the cooling pipe extend out of the outside of the absorption liquid storage tank respectively. The cooling liquid inlet of the cooling pipe is located at the lower side of the cooling liquid outlet.

5. The lithium hexafluorophosphate production tail gas treatment system according to claim 1, characterized in that: The boost pump is located on the upper side of the coolant storage tank, and the lower end of the liquid outlet pipe of the coolant storage tank extends to the lower side of the coolant storage tank.

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