Lithium hexafluorophosphate synthesis tail gas treatment device

Abstract

The utility model relates to a lithium hexafluorophosphate synthesis tail gas treatment device. According to the technical scheme, the output end of a temporary storage tank is connected to a side line of a first rectifying tower through a pipeline and connected to a side line of a second rectifying tower through another pipeline, the tops of the first rectifying tower and the second rectifying tower are connected to a shell pass inlet of a tail gas condenser through pipelines, and a shell pass upper outlet is connected with a tail gas condensation recoverer through a pipeline; a shell pass lower outlet of the tail gas condenser is connected with a first buffer tank, and the lower end of the first buffer tank is connected to a dimethyl carbonate recovery tank; the bottoms of the first rectifying tower and the second rectifying tower are respectively connected to a tube pass inlet of the lithium hexafluorophosphate condenser through pipelines, and a tube pass outlet is connected with a lithium hexafluorophosphate crude product temporary storage tank through a pipeline. The method has the beneficial effects that the dimethyl carbonate, the hydrogen fluoride and the hydrogen chloride can be separated from the product in the lithium hexafluorophosphate synthesis section through condensation treatment at different temperatures, so that different products are respectively obtained, and the economic benefit is improved.

Description

Technical Field

[0001] The utility model relates to a lithium hexafluorophosphate synthesis device, in particular to a lithium hexafluorophosphate synthesis tail gas treatment device. Background Art

[0002] Lithium hexafluorophosphate (LiPF6) is an inorganic substance in the form of white crystals or powder. It is readily soluble in water and in low-concentration organic solvents such as methanol, ethanol, acetone, and carbonates. As the most commonly used electrolyte material in lithium-ion batteries, LiPF6 faces increasing demand and quality requirements. Currently, the industrial method for directly synthesizing LiPF6 is primarily based on phosphorus pentafluoride and lithium fluoride in a solvent. This process produces off-gases such as HCl and HF. Existing treatment methods typically use alkaline solutions, which hinders product recycling. Since the boiling point of HF is 19.5°C and that of HCl is -85°C, cooling the gas mixture to between -85°C and 19.5°C liquefies the HF while leaving the HCl in a gaseous state. This allows the two to be separated, yielding higher-purity HCl for the production of hydrochloric acid, expanding its application. Utility Model Content

[0003] The purpose of the utility model is to address the above-mentioned defects of the prior art and provide a lithium hexafluorophosphate synthesis tail gas treatment device. The output of the lithium hexafluorophosphate synthesis section is condensed at different temperatures to separate dimethyl carbonate, hydrogen fluoride and hydrogen chloride, thereby obtaining different products respectively and improving economic benefits.

[0004] The utility model discloses a lithium hexafluorophosphate synthesis tail gas treatment device, and its technical solution is as follows: comprising a first distillation tower (1), a second distillation tower (2), a temporary storage tank (3), a tail gas condenser (4), a first buffer tank (5), a lithium hexafluorophosphate condenser (6), a tail gas condensation recovery device (7), a dimethyl carbonate recovery tank (8), a lithium hexafluorophosphate crude product temporary storage tank (9), a first reboiler (10), and a second reboiler (11), wherein the output end of the temporary storage tank (3) is connected to the side line of the first distillation tower (1) through a pipeline, and is connected to the side line of the second distillation tower (2) through another pipeline, and the first distillation tower (1) is connected to the side line of the second distillation tower (2). The top of the first rectifying tower (1) and the second rectifying tower (2) are connected to the shell-side inlet of the tail gas condenser (4) through a pipeline, the shell-side upper outlet of the tail gas condenser (4) is connected to the tail gas condensate recovery device (7) through a pipeline, the shell-side lower outlet of the tail gas condenser (4) is connected to the first buffer tank (5) through a pipeline, and the lower end of the first buffer tank (5) is connected to the dimethyl carbonate recovery tank (8) through a pipeline; the bottoms of the first rectifying tower (1) and the second rectifying tower (2) are respectively connected to the tube-side inlet of the lithium hexafluorophosphate condenser (6) through a pipeline, and the tube-side outlet of the lithium hexafluorophosphate condenser (6) is connected to the lithium hexafluorophosphate crude product temporary storage tank (9) through a pipeline.

[0005] Preferably, the tail gas condensation recovery device (7) comprises a first condenser (7.1), a second condenser (7.2), a liquid hydrogen fluoride storage tank (7.3), a hydrogen chloride gas processing tank (7.4), a hydrochloric acid storage tank (7.5), a mixed gas delivery pipe (7.9), and a tail gas exhaust pipe (7.10), wherein the shell side inlet of the first condenser (7.1) is connected to the mixed gas delivery pipe (7.9), and the top outlet of the shell side of the first condenser (7.1) is connected to the second condenser (7.1) through a pipeline. 2), the shell side inlet of the first condenser (7.1), the bottom outlet of the shell side of the first condenser (7.1) is connected to the liquid hydrogen fluoride storage tank (7.3) through a pipeline; the bottom outlet of the shell side of the second condenser (7.2) is connected to the liquid hydrogen fluoride storage tank (7.3) through a pipeline, the top outlet of the shell side of the second condenser (7.2) is connected to the hydrogen chloride gas treatment tank (7.4) through a pipeline, the top of the hydrogen chloride gas treatment tank (7.4) is connected to the tail gas exhaust pipe (7.10), and the bottom is connected to the hydrochloric acid storage tank (7.5).

[0006] Preferably, an atomizer (7.4.1) is installed in the inner cavity of the above-mentioned hydrogen chloride gas treatment tank (7.4), and the input end of the atomizer (7.4.1) is connected to the lower side of the second buffer tank (7.6) through a pipeline and a circulation pump (7.7), and the upper side of the second buffer tank (7.6) is connected to the lower side of the hydrogen chloride gas treatment tank (7.4) through a pipeline.

[0007] Preferably, the bottom outlet of the hydrogen chloride gas treatment tank (7.4) is connected to the hydrochloric acid storage tank (7.5) through a pipeline and a control valve (7.8).

[0008] Preferably, the bottom of the first distillation tower (1) is provided with a first reboiler (10), and the bottom of the second distillation tower (2) is provided with a second reboiler (11).

[0009] Preferably, the output end of the temporary storage tank (3) is connected to the side line of the first distillation tower (1) through a pipeline and a first control valve (12), and is connected to the side line of the second distillation tower (2) through another pipeline and a second control valve (13).

[0010] The utility model has the following beneficial effects: the lithium hexafluorophosphate solution after distillation passes through the lithium hexafluorophosphate condenser and enters the lithium hexafluorophosphate crude product temporary storage tank; the mixed gas containing dimethyl carbonate is sent to the tail gas condenser through the top of the first distillation tower and the pipeline for treatment; the dimethyl carbonate is condensed and sent to the first buffer tank; the lower end of the first buffer tank is connected to the dimethyl carbonate recovery tank through a pipeline; the hydrogen fluoride and hydrogen chloride gases in the mixed gas are sent to the tail gas condensation recovery device for treatment; since the boiling point of HF is 19.5° C. and the boiling point of HCl is −85° C., the mixed gas is cooled to between −85° C. and 19.5° C. by passing through the first condenser and the second condenser, the HF is liquefied and recovered in the hydrogen fluoride storage tank, while the HCl remains in a gaseous state, so that the two can be separated, and the HCl gas is then sent to the hydrogen chloride gas treatment tank, thereby obtaining hydrochloric acid with higher purity, thereby increasing the scope of use of the hydrochloric acid; in addition, in order to increase the concentration of the hydrochloric acid, it can be circulated through the second buffer tank and the circulation pump, thereby increasing the concentration of the hydrochloric acid and reducing the use of water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of the utility model;

[0012] Figure 2 It is a structural diagram of the tail gas condensation recovery device;

[0013] In the figure above: first distillation tower 1, second distillation tower 2, temporary storage tank 3, tail gas condenser 4, first buffer tank 5, lithium hexafluorophosphate condenser 6, tail gas condensate recovery device 7, dimethyl carbonate recovery tank 8, crude lithium hexafluorophosphate temporary storage tank 9, first reboiler 10, second reboiler 11, first control valve 12, second control valve 13, third control valve 14, fourth control valve 15, fifth control valve 16, sixth control valve 17, first condenser 7.1, second condenser 7.2, liquid hydrogen fluoride storage tank 7.3, hydrogen chloride gas treatment tank 7.4, hydrochloric acid storage tank 7.5, second buffer tank 7.6, circulation pump 7.7, control valve 7.8, mixed gas delivery pipe 7.9, tail gas exhaust pipe 7.10. DETAILED DESCRIPTION

[0014] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0015] Example 1, reference Figure 1 and Figure 2 The utility model mentions a lithium hexafluorophosphate synthesis tail gas treatment device, comprising a first distillation tower 1, a second distillation tower 2, a temporary storage tank 3, a tail gas condenser 4, a first buffer tank 5, a lithium hexafluorophosphate condenser 6, a tail gas condensation recovery device 7, a dimethyl carbonate recovery tank 8, a lithium hexafluorophosphate crude product temporary storage tank 9, a first reboiler 10, a second reboiler 11, a first control valve 12, a second control valve 13, a third control valve 14, a fourth control valve 15, a fifth control valve 16, and a sixth control valve 17. The output end of the temporary storage tank 3 is connected to the side line of the first distillation tower 1 through a pipeline, and is connected to the side line of the first distillation tower 1 through another pipeline. To the side line of the second distillation tower 2, the top of the first distillation tower 1 and the second distillation tower 2 are connected to the shell side inlet of the tail gas condenser 4 through a pipeline, the upper shell side outlet of the tail gas condenser 4 is connected to the tail gas condensation recovery device 7 through a pipeline, the lower shell side outlet of the tail gas condenser 4 is connected to the first buffer tank 5 through a pipeline, and the lower end of the first buffer tank 5 is connected to the dimethyl carbonate recovery tank 8 through a pipeline; the bottoms of the first distillation tower 1 and the second distillation tower 2 are respectively connected to the tube side inlet of the lithium hexafluorophosphate condenser 6 through pipelines, and the tube side outlet of the lithium hexafluorophosphate condenser 6 is connected to the lithium hexafluorophosphate crude product temporary storage tank 9 through a pipeline.

[0016] Reference Figure 2 The tail gas condensation recovery device 7 mentioned in the present invention includes a first condenser 7.1, a second condenser 7.2, a liquid hydrogen fluoride storage tank 7.3, a hydrogen chloride gas treatment tank 7.4, a hydrochloric acid storage tank 7.5, a mixed gas delivery pipe 7.9, and a tail gas exhaust pipe 7.10. The shell side inlet of the first condenser 7.1 is connected to the mixed gas delivery pipe 7.9, the top outlet of the shell side of the first condenser 7.1 is connected to the shell side inlet of the second condenser 7.2 through a pipeline, and the bottom outlet of the shell side of the first condenser 7.1 is connected to the liquid hydrogen fluoride storage tank 7.3 through a pipeline; the bottom outlet of the shell side of the second condenser 7.2 is connected to the liquid hydrogen fluoride storage tank 7.3 through a pipeline, and the top outlet of the shell side of the second condenser 7.2 is connected to the hydrogen chloride gas treatment tank 7.4 through a pipeline. The top of the hydrogen chloride gas treatment tank 7.4 is connected to the tail gas exhaust pipe 7.10, and the bottom is connected to the hydrochloric acid storage tank 7.5.

[0017] The inner cavity of the hydrogen chloride gas treatment tank 7.4 is equipped with an atomizer 7.4.1, and the input end of the atomizer 7.4.1 is connected to the lower side of the second buffer tank 7.6 through a pipeline and a circulation pump 7.7. The upper side of the second buffer tank 7.6 is connected to the lower side of the hydrogen chloride gas treatment tank 7.4 through a pipeline.

[0018] The bottom outlet of the hydrogen chloride gas treatment tank 7.4 is connected to the hydrochloric acid storage tank 7.5 through a pipeline and a control valve 7.8.

[0019] A first reboiler 10 is provided at the bottom of the first distillation tower 1 , and a second reboiler 11 is provided at the bottom of the second distillation tower 2 .

[0020] In addition, the output end of the temporary storage tank 3 is connected to the side line of the first distillation tower 1 through a pipeline and a first control valve 12, and is connected to the side line of the second distillation tower 2 through another pipeline and a second control valve 13. In addition, the upper end of the first distillation tower 1 is connected to the tail gas condenser 4 through a third control valve 14 and a pipeline, and the upper end of the second distillation tower 2 is connected to the tail gas condenser 4 through a fourth control valve 15 and a pipeline; the lower end of the first distillation tower 1 is connected to the lithium hexafluorophosphate condenser 6 through a fifth control valve 16 and a pipeline, and the lower end of the second distillation tower 2 is connected to the lithium hexafluorophosphate condenser 6 through a sixth control valve 17 and a pipeline.

[0021] When the utility model is used, the first control valve 12 or the second control valve 13 is opened first, and the output of the lithium hexafluorophosphate synthesis section in the temporary storage tank 3 enters the first distillation tower 1 through the pipeline and the first control valve 12, or enters the second distillation tower 2 through the pipeline and the second control valve 13. The lithium hexafluorophosphate solution after distillation passes through the lithium hexafluorophosphate condenser 6 and then enters the lithium hexafluorophosphate crude product temporary storage tank 9; the mixed gas containing dimethyl carbonate is sent to the tail gas condenser 4 for treatment through the top of the first distillation tower 1 or the second distillation tower 2 and the pipeline. Since the boiling point of dimethyl carbonate is 90°C-91°C, the dimethyl carbonate can be condensed by cooling to between 19.5°C and 90°C, and then sent to the first buffer tank 5 for recovery. The lower end of the first buffer tank 5 is connected to the dimethyl carbonate recovery tank 8 through a pipeline, and the hydrogen fluoride and hydrogen chloride gases in the mixed gas are sent to the tail gas condensation recovery device 7 for treatment; since the boiling point of HF is 19.5 The boiling point of HCl is -85°C. Therefore, the mixed gas is cooled to a temperature between -85°C and 19.5°C by passing through the first condenser 7.1 and the second condenser 7.2. The HF is liquefied and recovered in the hydrogen fluoride storage tank 7.3, while the HCl remains in a gaseous state. The two can then be separated and the HCl gas is then sent to the hydrogen chloride gas treatment tank 7.4, thereby obtaining higher-purity hydrochloric acid. In addition, to increase the concentration of the hydrochloric acid, it can be circulated through the second buffer tank 7.6 and the circulation pump 7.7, thereby increasing the concentration of the hydrochloric acid and reducing the use of water resources.

[0022] Example 2. A lithium hexafluorophosphate synthesis tail gas treatment device mentioned in the present invention comprises a first distillation tower 1, a temporary storage tank 3, a tail gas condenser 4, a first buffer tank 5, a lithium hexafluorophosphate condenser 6, a tail gas condensation recovery device 7, a dimethyl carbonate recovery tank 8, a lithium hexafluorophosphate crude product temporary storage tank 9, and a first reboiler 10. The output end of the temporary storage tank 3 is connected to the side line of the first distillation tower 1 through a pipeline, the top of the first distillation tower 1 is connected to the shell side inlet of the tail gas condenser 4 through a pipeline, the upper shell side outlet of the tail gas condenser 4 is connected to the tail gas condensation recovery device 7 through a pipeline, the lower shell side outlet of the tail gas condenser 4 is connected to the first buffer tank 5 through a pipeline, and the lower end of the first buffer tank 5 is connected to the dimethyl carbonate recovery tank 8 through a pipeline; the bottom of the first distillation tower 1 is connected to the tube side inlet of the lithium hexafluorophosphate condenser 6 through a pipeline, and the tube side outlet of the lithium hexafluorophosphate condenser 6 is connected to the lithium hexafluorophosphate crude product temporary storage tank 9 through a pipeline.

[0023] The difference from Example 1 is that only the first distillation tower 1 is used, and the purpose of the utility model can also be basically achieved. In addition, when used in this embodiment, the first control valve 12 is first opened, and the output of the lithium hexafluorophosphate synthesis section in the temporary storage tank 3 enters the first distillation tower 1 through the pipeline and the first control valve 12. The lithium hexafluorophosphate solution after distillation passes through the lithium hexafluorophosphate condenser 6 and enters the lithium hexafluorophosphate crude product temporary storage tank 9; the mixed gas containing dimethyl carbonate is sent to the tail gas condenser 4 for treatment through the top of the first distillation tower 1 and the pipeline, and the dimethyl carbonate is condensed and sent to the first buffer tank 5. The lower end of the first buffer tank 5 is connected to the dimethyl carbonate recovery tank 8 through a pipeline, and the hydrogen fluoride and hydrogen chloride gases in the mixed gas are sent to the tail gas condensation recovery device 7 for treatment; since the boiling point of HF is 19.5 The boiling point of HCl is -85°C. Therefore, the mixed gas is cooled to a temperature between -85°C and 19.5°C by passing through a first condenser 7.1 and a second condenser 7.2. The HF is liquefied and recovered in a hydrogen fluoride storage tank 7.3, while the HCl remains in a gaseous state. The two gases can then be separated and the HCl gas is then fed to a hydrogen chloride gas treatment tank 7.4, thereby obtaining higher-purity hydrochloric acid. Furthermore, to increase the concentration of the hydrochloric acid, it can be circulated through a second buffer tank 7.6 and a circulation pump 7.7, thereby increasing the concentration of the hydrochloric acid and reducing water usage.

[0024] The above description is merely a preferred embodiment of the present invention. Anyone skilled in the art may utilize the above-described technical solutions to modify the present invention or create equivalent technical solutions. Therefore, any simple modifications or equivalent transformations based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A lithium hexafluorophosphate synthesis tail gas treatment device, characterized by: The invention comprises a first rectifying tower (1), a second rectifying tower (2), a temporary storage tank (3), a tail gas condenser (4), a first buffer tank (5), a lithium hexafluorophosphate condenser (6), a tail gas condensation recovery device (7), a dimethyl carbonate recovery tank (8), a lithium hexafluorophosphate crude product temporary storage tank (9), a first reboiler (10), and a second reboiler (11), wherein the output end of the temporary storage tank (3) is connected to the side line of the first rectifying tower (1) through a pipeline, and is connected to the side line of the second rectifying tower (2) through another pipeline, and the tops of the first rectifying tower (1) and the second rectifying tower (2) are connected through a pipeline. The shell side inlet of the tail gas condenser (4) is connected to the shell side inlet of the tail gas condenser (4), the shell side upper outlet of the tail gas condenser (4) is connected to the tail gas condensation recovery device (7) through a pipeline, the shell side lower outlet of the tail gas condenser (4) is connected to the first buffer tank (5) through a pipeline, and the lower end of the first buffer tank (5) is connected to the dimethyl carbonate recovery tank (8) through a pipeline; the bottoms of the first distillation tower (1) and the second distillation tower (2) are respectively connected to the tube side inlet of the lithium hexafluorophosphate condenser (6) through pipelines, and the tube side outlet of the lithium hexafluorophosphate condenser (6) is connected to the lithium hexafluorophosphate crude product temporary storage tank (9) through a pipeline; The tail gas condensation recovery device (7) comprises a first condenser (7.1), a second condenser (7.2), a liquid hydrogen fluoride storage tank (7.3), a hydrogen chloride gas processing tank (7.4), a hydrochloric acid storage tank (7.5), a mixed gas delivery pipe (7.9), and a tail gas exhaust pipe (7.10). The shell side inlet of the first condenser (7.1) is connected to the mixed gas delivery pipe (7.9), and the top outlet of the shell side of the first condenser (7.1) is connected to the second condenser (7.2) through a pipeline. The shell side inlet of the first condenser (7.1) is connected to the liquid hydrogen fluoride storage tank (7.3) through a pipeline at the bottom outlet of the shell side of the second condenser (7.2). The shell side top outlet of the second condenser (7.2) is connected to the liquid hydrogen fluoride storage tank (7.3) through a pipeline. The shell side top outlet of the second condenser (7.2) is connected to the hydrogen chloride gas treatment tank (7.4) through a pipeline. The top of the hydrogen chloride gas treatment tank (7.4) is connected to the tail gas exhaust pipe (7.10), and the bottom is connected to the hydrochloric acid storage tank (7.5).

2. The lithium hexafluorophosphate synthesis tail gas treatment device according to claim 1, characterized in that: An atomizer (7.4.1) is installed in the inner cavity of the hydrogen chloride gas treatment tank (7.4), and the input end of the atomizer (7.4.1) is connected to the lower side of the second buffer tank (7.6) through a pipeline and a circulation pump (7.7), and the upper side of the second buffer tank (7.6) is connected to the lower side of the hydrogen chloride gas treatment tank (7.4) through a pipeline.

3. The lithium hexafluorophosphate synthesis tail gas treatment device according to claim 2, characterized in that: The bottom outlet of the hydrogen chloride gas treatment tank (7.4) is connected to the hydrochloric acid storage tank (7.5) through a pipeline and a control valve (7.8).

4. The lithium hexafluorophosphate synthesis tail gas treatment device according to claim 1 or 3, characterized in that: The bottom of the first distillation tower (1) is provided with a first reboiler (10), and the bottom of the second distillation tower (2) is provided with a second reboiler (11).

5. The lithium hexafluorophosphate synthesis tail gas treatment device according to claim 4, characterized in that: The output end of the temporary storage tank (3) is connected to the side line of the first distillation tower (1) through a pipeline and a first control valve (12), and is connected to the side line of the second distillation tower (2) through another pipeline and a second control valve (13).

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