Anhydrous hydrogen fluoride recovery device in lithium hexafluorophosphate production

Abstract

The utility model relates to the technical field of lithium hexafluorophosphate production devices, and particularly discloses an anhydrous hydrogen fluoride recovery device in lithium hexafluorophosphate production. Comprising a machine frame, a condenser is arranged on the machine frame, a storage tank for storing liquid anhydrous hydrogen fluoride is arranged below the machine frame, a rapid liquid discharging pipe is arranged between the condenser and the storage tank, a plurality of communicating pipes and a plurality of discharging pipes are arranged on the rapid liquid discharging pipe, the communicating pipes are all communicated with the condenser, and the discharging pipes are communicated with the storage tank. The technical problems that in the prior art, when a tubular condenser is directly used for recycling anhydrous hydrogen fluoride, liquid drainage of the condenser is not smooth, and liquid anhydrous hydrogen fluoride is accumulated in the condenser are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of cement experiments, in particular to an anhydrous hydrogen fluoride recovery device in the production of lithium hexafluorophosphate. Background Art

[0002] Anhydrous hydrogen fluoride is a colorless, transparent compound that is liquid at low temperatures. It is extremely volatile and forms smoke. Anhydrous hydrogen fluoride has very strong chemical activity and can react with alkalis, metals, oxides, and silicates. It can react with water to produce hydrofluoric acid. It is widely used in many industries as a strong oxidant and is the basic raw material for the manufacture of elemental fluorine, fluorine refrigerants, inorganic fluorides, and organic fluorides.

[0003] Lithium hexafluorophosphate (LFP) is a key lithium-ion battery electrolyte widely used in the preparation of electrolytes. Its high solubility and conductivity in organic solvents, combined with its excellent electrochemical stability and environmental friendliness, make it the primary electrolyte in lithium-ion battery electrolytes. Due to its critical role in lithium battery electrolytes and its potential applications in other fields, LFP is becoming a hot topic in the field of new energy materials.

[0004] Anhydrous hydrogen fluoride plays a vital role in the process of producing lithium hexafluorophosphate. In the hydrogen fluoride solvent method, anhydrous hydrogen fluoride is used as a solvent to dissolve lithium fluoride, and then high-purity phosphorus pentafluoride gas is introduced to react to generate lithium hexafluorophosphate crystals. Anhydrous hydrogen fluoride and lithium hexafluorophosphate easily form complexes, which helps to improve the purity of lithium hexafluorophosphate. However, during the reaction, anhydrous hydrogen fluoride, as a solvent, will volatilize during the reaction process and enter the waste gas collection tank with other tail gases of the synthesis tank (such as nitrogen, hydrogen chloride, etc.). However, anhydrous hydrogen fluoride is an important solvent for production. Direct treatment and discharge not only requires cost for treatment, but also causes waste of anhydrous hydrogen fluoride. Therefore, in the prior art, the first and second condensers of the deep cold tail gas section are used for condensation. The first and second condensers use the different liquefaction temperatures of the gases in the tail gas and use -75℃ dichloromethane as a refrigerant to condense the anhydrous hydrogen fluoride gas in the tail gas for recycling.

[0005] However, the condenser commonly used in the prior art is a tubular condenser. During use, due to the low boiling point of anhydrous hydrogen fluoride, dichloromethane at -75°C is used as a refrigerant for cooling, which can quickly condense the anhydrous hydrogen fluoride. When a large amount of volatilized anhydrous hydrogen fluoride is generated, or when the amount of tail gas suddenly increases due to production reasons, a large amount of anhydrous hydrogen fluoride condenses in the tubular condenser. The condensed liquid anhydrous hydrogen fluoride needs to flow along the condenser to the tail before it can be discharged, resulting in poor drainage and accumulation of liquid anhydrous hydrogen fluoride in the condenser. This in turn prevents subsequent tail gas from entering the condenser, forcing production to be interrupted. Utility Model Content

[0006] The purpose of the utility model is to provide an anhydrous hydrogen fluoride recovery device for lithium hexafluorophosphate production, so as to solve the technical problem in the prior art mentioned above that when anhydrous hydrogen fluoride is directly recovered using a tubular condenser, the condenser is not drained smoothly and liquid anhydrous hydrogen fluoride accumulates in the condenser.

[0007] In order to solve the above problems, the technical solution adopted by the utility model is as follows: a device for recovering anhydrous hydrogen fluoride in the production of lithium hexafluorophosphate, comprising a frame, a condenser provided on the frame, a storage tank for storing liquid anhydrous hydrogen fluoride provided under the frame, a quick drain pipe provided between the condenser and the storage tank, a plurality of connecting pipes and discharge pipes provided on the quick drain pipe, the connecting pipes are all connected to the condenser, and the discharge pipe is connected to the storage tank.

[0008] The beneficial effects of this embodiment are:

[0009] 1. In the prior art, when anhydrous hydrogen fluoride is recovered, the anhydrous hydrogen fluoride in the exhaust gas is condensed into liquid and needs to flow along the condenser to the tail before it can be discharged. When the amount of volatilized anhydrous hydrogen fluoride is large, or the amount of exhaust gas suddenly increases due to production reasons, the amount of anhydrous hydrogen fluoride condensed in the tubular condenser is large, and the condensed anhydrous hydrogen fluoride needs to flow along the condenser to the tail before it can be discharged, resulting in poor drainage and accumulation of liquid anhydrous hydrogen fluoride in the condenser, which in turn prevents subsequent exhaust gas from entering the condenser and forces production to be interrupted. However, the present application provides a quick drain pipe between the condenser and the storage tank, and a plurality of connecting pipes connected to the condenser are provided on the quick drain pipe. The anhydrous hydrogen fluoride condensed in the condenser is quickly discharged by using multiple connecting pipes. Therefore, the present application does not cause accumulation of liquid anhydrous hydrogen fluoride, which in turn prevents subsequent exhaust gas from entering the condenser and forces production to be interrupted.

[0010] Furthermore, the end of the discharge pipe is provided with a discharge elbow, which can form a liquid seal structure to prevent the condenser from being directly connected to the storage tank.

[0011] Furthermore, the condenser includes a tube array, each end of which is provided with a shunt pipe, and a heat exchange pipe having a smaller diameter than the shunt pipe is connected between the shunt pipes at both ends of the tube array. The heat exchange pipe increases the heat exchange area between the exhaust gas and the refrigerant, thereby improving the heat exchange efficiency.

[0012] Furthermore, the condenser is provided with a baffle having a through hole for the heat exchange tube to pass through. The baffle prolongs the heat exchange time between the exhaust gas and the refrigerant, thereby ensuring sufficient condensation of the anhydrous hydrogen fluoride.

[0013] Furthermore, there are two condensers, and the two condensers are connected in series.

[0014] Furthermore, a fixing right-angle plate for fixing the condenser is provided on the rack, so that the condenser is installed on the rack more stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of an embodiment of the utility model.

[0016] Figure 2 This is a structural diagram of another perspective of an embodiment of the utility model.

[0017] Figure 3 This is a schematic diagram of the connection structure of the condenser, quick drain pipe and storage tank in an embodiment of the utility model. DETAILED DESCRIPTION

[0018] The following is further described in detail through specific implementation methods:

[0019] The figure marks in the drawings of the specification include: frame 1, table panel 11, fixed right-angle plate 12, fixing bolt 121, condenser 2, air inlet pipe 21, intermediate air outlet pipe 22, intermediate air outlet valve 221, air outlet pipe 23, straight-through pipe 24, straight-through valve 241, tube array 25, tube array liquid outlet 251, baffle 252, quick drain pipe 3, connecting pipe 31, discharge pipe 32, discharge elbow 321, storage tank 4.

[0020] Implementation example Figures 1 to 3 The figure shows an anhydrous hydrogen fluoride recovery device for lithium hexafluorophosphate production, comprising a frame 1. The frame 1 is a four-legged frame structure formed by beams and columns, with slats welded to the bottom of the four-legged columns. A tabletop 11 is welded to the middle of the upper end surface of the frame 1. The tabletop 11 is at the same height as the beams of the frame 1 and forms a mounting table on the upper end surface of the frame 1 for mounting a condenser 2. Figure 1 The direction is a description direction. The condenser 2 is installed on the center of the front and rear of the rack 1, and ensure that the center line of the condenser 2 coincides with the rack 1. A notch is provided on the corresponding crossbeam of the rack 1, and a protrusion is provided on the outer shell of the condenser 2. The condenser 2 can be clamped on the rack 1 by using the notch and the protrusion. After clamping, fixed right-angle plates 12 are provided in the front and back of the condenser 2 to limit the condenser 2. The fixed right-angle plates 12 are fixed to the crossbeam and table panel 11 of the rack 1 by fixing bolts 121, thereby ensuring that the condenser 2 is well installed on the upper end of the rack 1.

[0021] Since the crossbeam of the frame 1 and the table panel 11 are hollow, the condenser 2 is exposed under the frame 1. A storage tank 4 is provided under the frame. The storage tank 4 is directly mounted on the ground with bolts. A quick drain pipe 3 is also provided between the storage tank 4 and the condenser 2. The quick drain pipe 3 is a pipe body with both ends blocked. A plurality of connecting pipes 31 are welded to the upper end of the quick drain pipe 3. One end of the connecting pipe 31 is connected to the quick drain pipe 3 by welding, and the other end is connected to the inside of the condenser 2. When welding the connecting pipe 31, it is necessary to ensure that the weld is sealed to prevent liquid leakage and gas leakage. A discharge pipe 32 is welded to the other surface of the quick drain pipe 3 opposite to the connection pipe 31. One end of the discharge pipe 32 is welded to the quick drain pipe 3, and the other end directly extends into the internal space of the storage tank 4. The end of the discharge pipe 32 is bent into a discharge elbow 321. Therefore, the liquid anhydrous hydrogen fluoride discharged into the storage tank through the discharge pipe 32 will form a liquid seal structure at the elbow 321, preventing the anhydrous hydrogen fluoride in the storage tank 4 from volatilizing again and flowing back into the condenser 2, and also preventing other exhaust gases in the condenser 2 from entering the storage tank.

[0022] The condenser 2 is a cylindrical shell with tubes 25 arranged inside, thus forming two cavities. The -75°C refrigerant dichloromethane flows through the tube cavity of the tube 25, and the exhaust gas flows from the shell cavity between the shell and the tube 25. The exhaust gas and the refrigerant exchange heat. The anhydrous hydrogen fluoride in the exhaust gas is condensed and falls to the bottom of the shell cavity, flows into the quick drain pipe 3 through the connecting pipe 31, and is discharged into the storage tank 4.

[0023] like Figure 1 、 Figure 3 As shown, Figure 3 The direction is a description direction. The left end of the condenser 2 is the air inlet pipe 21. The exhaust gas or tail gas enters the shell cavity of the condenser 2 from the air inlet pipe 21. The refrigerant enters the tube cavity from the tube liquid inlet at the upper end of the condenser 2 and flows out from the tube liquid outlet 251. The flow direction of the refrigerant is opposite to that of the exhaust gas. Therefore, the air inlet 21 and the tube liquid outlet 251 are located at the same end of the condenser 2. A baffle 252 is provided in the shell cavity of the condenser 2. The baffle 252 is welded to the front and back of the condenser 2. Therefore, the exhaust gas cannot pass through the condenser 2 directly, and needs to flow along the baffle 252 to bend back and forth to increase the heat exchange time between the exhaust gas and the refrigerant. The tube array 25 is not a straight metal tube. There are diversion tubes at both ends of the tube array 25. There are several heat exchange tubes with a diameter smaller than the diversion tube between the diversion tubes. When the heat exchange tube encounters the deflector 252, the deflector 252 is provided with a through hole for the heat exchange tube to pass through. Therefore, the deflector 252 also plays a fixing role for the heat exchange tube. The heat exchange tube connects the diversion tubes at both ends. Therefore, the refrigerant flowing into the tube array 25 will be diverted by the diversion tube and flow into different heat exchange tubes, which increases the heat exchange area between the refrigerant and the exhaust gas.

[0024] In this embodiment, the condenser 2 is not a larger condenser, but two relatively small condensers 2 are set, and the two condensers 2 are symmetrically installed along the center line of the table panel 11 of the frame 1, and are connected in series using a straight pipe 24. An intermediate air outlet pipe 22 is provided on the straight pipe 24 using a tee, and an intermediate air outlet valve 221 is provided on the intermediate air outlet pipe 22, and a straight valve 241 is provided on the straight pipe 24. Therefore, the intermediate air outlet valve 221 and the straight valve 241 can be used to control whether to use one condenser 2 or two. This method allows the recovery device of the present application to adjust the input of the condenser 2 according to the amount of waste gas and the production status, which is more flexible. If two condensers 2 are used, the waste gas flows out from the air outlet pipe 23 at the right end.

[0025] The above is only an embodiment of the present invention, and the commonly known specific structures and characteristics of the scheme are not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, and these should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection claimed by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A device for recovering anhydrous hydrogen fluoride in the production of lithium hexafluorophosphate, comprising a frame, a condenser provided on the frame, and a storage tank for storing liquid anhydrous hydrogen fluoride provided under the frame, characterized in that: A quick drain pipe is provided between the condenser and the storage tank. The quick drain pipe is provided with a plurality of connecting pipes and discharge pipes. The connecting pipes are all connected to the condenser, and the discharge pipes are connected to the storage tank.

2. The anhydrous hydrogen fluoride recovery device in the production of lithium hexafluorophosphate according to claim 1, characterized in that: The end of the discharge pipe is provided with a discharge elbow.

3. The anhydrous hydrogen fluoride recovery device in the production of lithium hexafluorophosphate according to claim 1, characterized in that: The condenser comprises a tube array, both ends of the tube array are provided with a shunt tube, and a heat exchange tube with a smaller diameter than the shunt tube is provided between the shunt tubes at both ends of the tube array to connect them.

4. The anhydrous hydrogen fluoride recovery device for lithium hexafluorophosphate production according to claim 3, characterized in that: The condenser is provided with a baffle, and the baffle is provided with a through hole for the heat exchange tube to pass through.

5. The anhydrous hydrogen fluoride recovery device in the production of lithium hexafluorophosphate according to claim 1, characterized in that: There are two condensers, and the two condensers are connected in series.

6. The anhydrous hydrogen fluoride recovery device in the production of lithium hexafluorophosphate according to claim 1, characterized in that: The frame is provided with a fixed right-angle plate for fixing the condenser.

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