A condensation recovery device and process for tail gas containing hydrogen fluoride and hydrogen chloride

Abstract

The invention discloses a condensation recovery device and process for tail gas containing hydrogen fluoride and hydrogen chloride, wherein the tail gas condensation recovery device containing hydrogen fluoride and hydrogen chloride comprises a liquid nitrogen condenser for condensing waste gas, wherein the air inlet of the liquid nitrogen condenser is connected with the waste gas, the air outlet is connected with the inlet of an adsorption device or a compressor, and the liquid outlet of the liquid nitrogen condenser is connected with the inlet of a storage tank, so that the liquid HF condensed by the liquid nitrogen condenser is input into the storage tank for storage. The invention has a simple process, high separation efficiency for HF and HCL, can create economic value, and reduce the high cost problem caused by waste gas treatment.

Description

Technical Field

[0001] The invention relates to a waste gas treatment technology in the production process of lithium hexafluorophosphate, and in particular to a condensation recovery device and process for tail gas containing hydrogen fluoride and hydrogen chloride. Background Art

[0002] Lithium hexafluorophosphate is an important raw material (electrolyte) for new energy batteries. A large amount of anhydrous hydrogen fluoride and hydrogen chloride gas is produced during the production process of lithium hexafluorophosphate. The existing treatment method is to absorb the anhydrous hydrogen fluoride and hydrogen chloride gas into fluorine-containing hydrochloric acid or treat them as wastewater, which seriously wastes resources and affects the economic benefits of the enterprise. Summary of the invention

[0003] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a condensation recovery device and process for tail gas containing hydrogen fluoride and hydrogen chloride, which can recycle the waste gas in the production process of lithium hexafluorophosphate.

[0004] To achieve the above-mentioned purpose, the present invention provides a condensation recovery device for tail gas containing hydrogen fluoride and hydrogen chloride, comprising a liquid nitrogen condenser, which is used to condense the waste gas, the air inlet of the liquid nitrogen condenser is connected with the waste gas, the air outlet is connected with the inlet of an adsorption device or a compressor, and the liquid outlet of the liquid nitrogen condenser is connected with the inlet of a storage tank, so that the liquid HF condensed by the liquid nitrogen condenser is input into the storage tank for storage.

[0005] Preferably, the compressor is used to compress gaseous HCL, and then store it in a gas cylinder to obtain industrial-grade cylinder gas.

[0006] Preferably, the adsorption device is used to adsorb HF in the gas, and high-purity HCL is compressed into a gas cylinder by a compressor to obtain high-purity cylinder gas.

[0007] Preferably, the adsorption device comprises two alumina adsorption tanks, one of which is used selectively, and the alumina adsorption tank comprises an outer box and an inner box, the inner box is installed inside the outer box and a heat preservation gap is formed between the inner box and the inner wall of the outer box, and a first coil is installed in the heat preservation gap;

[0008] At least two heating plates are fixed in the inner box, and the heating plates are provided with air holes and heating strips, and the inner box is filled with alumina, which is used to adsorb VOCs; the top of the inner side of the inner box is connected to one end of the first access pipe, the second access pipe, and the third access pipe, respectively, and the bottom of the inner box is connected to one end of the first access pipe, the second access pipe, and the third access pipe, respectively;

[0009] The air inlet pipe is connected to the inlet of the first reversing valve, and the first outlet and the second outlet of the first reversing valve are respectively connected to the other ends of the first secondary access pipes of the two alumina adsorption tanks, and when in use, the first reversing valve is used to selectively connect its inlet to one of the first secondary access pipes; the first access pipe is connected to the inlet of the first one-way valve, and the outlet of the first one-way valve is connected to the exhaust pipe, so as to output the treated gas.

[0010] Preferably, the second secondary access pipe is connected to the inlet of the fourth one-way valve, the outlet of the fourth one-way valve is connected to the condensation inlet of the condenser, and the condensation outlet of the condenser is connected to the inlet of the storage tank; the second access pipe is connected to the inlet of the second one-way valve, the outlet of the second one-way valve is connected to the inlet of the storage tank; the third secondary access pipe is connected to the inlet of the third one-way valve, and the outlet of the third one-way valve is connected to the condensation inlet of the condenser.

[0011] Preferably, the other ends of the third access pipes of the two alumina adsorption tanks are respectively connected to the first outlet and the second outlet of the second reversing valve, the inlet of the second reversing valve is connected to the outlet of the steam pump, the steam pump belongs to the steam system, and the steam system also includes a booster water pump, the inlet of the booster water pump is connected to the water source, and the outlet is connected to the inlet of the atomizer, the atomizer is used to atomize water, and the outlet of the atomizer is connected to the first inlet of the third reversing valve, the second inlet of the third reversing valve is connected to the external air source, the outlet of the third reversing valve is connected to one end of the heating gap of the heater, and the third reversing valve is used to select one of its first inlet and second inlet to be connected to its outlet;

[0012] The heater comprises a first shell and a second shell, a mounting gap is formed between the first shell and the second shell, a second coil is installed in the mounting gap, a first heating baffle and a second heating baffle arranged alternately are installed in the second shell, a heating gap is formed between the first heating baffle and the second heating baffle, and the other end of the heating gap is connected to the inlet of the steam pump;

[0013] The first heating baffle and the second heating baffle are made of iron material, an alternating current is passed through the second coil, and the second reversing valve is selectively connected to one of the third access pipes.

[0014] Preferably, the insulation gap is filled with insulation material; and the installation gap is filled with insulation cotton.

[0015] The present invention also discloses a condensation recovery process for tail gas containing hydrogen fluoride and hydrogen chloride, comprising the following steps:

[0016] S1. The waste gas of the mixed oil HF and HCL is input into the liquid nitrogen condenser, and the waste gas is cooled to -98°C by the liquid nitrogen condenser, so that the HF is liquefied and the HCL remains in gaseous state;

[0017] S2. Output the liquid phase for storage and output the separated gas for further processing.

[0018] Preferably, in S2, the separated gas is input into a compressor, compressed and bottled to obtain industrial-grade HCL cylinder gas.

[0019] Preferably, in S2, the separated gas is adsorbed by a multi-stage alumina adsorption tank to obtain high-purity HCL, thereby obtaining high-purity HCL gas.

[0020] The beneficial effects of the present invention are as follows: the process is simple, the separation efficiency of HF and HCL is high, and economic value can be created, thereby reducing the high cost problem caused by waste gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 It is a schematic structural diagram of the adsorption device of the present invention.

[0023] Figure 3 yes Figure 2 Enlarged view of F1 in the middle.

[0024] Figure 4 It is a schematic diagram of the steam system structure of the present invention. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0026] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] See also Figure 1 The condensation recovery device for tail gas containing hydrogen fluoride and hydrogen chloride in this embodiment includes a liquid nitrogen condenser, which is used to condense the waste gas. The air inlet of the liquid nitrogen condenser is connected to the waste gas, the air outlet is connected to the inlet of the adsorption device or the compressor, and the liquid outlet of the liquid nitrogen condenser is connected to the inlet of the storage tank, so that the liquid HF condensed by the liquid nitrogen condenser is input into the storage tank for storage;

[0028] The compressor is used to compress gaseous HCL, and then store it in a gas cylinder to obtain industrial-grade cylinder gas. The adsorption device is used to adsorb HF in the gas, thereby purifying HCL. The high-purity gas is compressed into the gas cylinder by the compressor to obtain high-purity cylinder gas.

[0029] The specific process is as follows:

[0030] Since the boiling point of HF is 19.5℃ and the boiling point of HCL is -85℃, the present invention utilizes the difference in boiling points between the two and uses a liquid nitrogen condenser to reduce the temperature of the mixed gas (tail gas) to -98℃ to separate HF and HCL; 85.12% hydrogen fluoride is obtained in the liquid phase, and the recovery rate of hydrogen fluoride is 99.9%, which can be used for the production of lithium hexafluorophosphate. The gas phase 99.8% HCL (containing less than 20ppm HF) is compressed and bottled and sold as industrial-grade HCL cylinder gas.

[0031] If after the liquid nitrogen is condensed, it is adsorbed and HF is removed using a multi-stage alumina adsorption tank, the purity of HCL can reach 99.999%, and the trace impurity value can be controlled below 5ppm, thus meeting the standard of high-purity HCL gas.

[0032] See also Figure 2-Figure 4 Although the amount of HF adsorbed by alumina in the alumina adsorption tank is very small, it is still necessary to replace the alumina adsorption tank to ensure the adsorption effect during the uninterrupted production process. Alumina will generate aluminum fluoride after absorbing HF, and aluminum fluoride can be partially hydrolyzed at 30-400°C to produce alumina and HF. If the alumina is hydrolyzed in a recycling method, the replacement frequency of the alumina adsorption tank can be greatly reduced, and the solid waste such as aluminum fluoride and alumina generated can also be reduced. Moreover, most of the HF after hydrolysis can be recycled. In addition, there are other impurities in the condensed gas, which can be filtered out by the alumina adsorption tank.

[0033] In order to ensure uninterrupted production, the applicant sets two alumina adsorption tanks for each adsorption device. The adsorption device includes two alumina adsorption tanks, and the two alumina adsorption tanks are used selectively. The alumina adsorption tank includes an outer box A110 and an inner box A120. The inner box A120 is installed inside the outer box A110 and a thermal insulation gap A111 is formed between the inner box A120 and the inner wall of the outer box A110. A first coil A210 is installed in the thermal insulation gap A111, and the thermal insulation gap A111 is filled with thermal insulation material A411, and the thermal insulation material A411 is a thermal insulation material, such as thermal insulation foam.

[0034] At least two heating plates A130 are fixed in the inner box A120, and the heating plates A130 are provided with air holes A131 and heating strips A132, and the inner box A120 is filled with aluminum oxide A412, and the aluminum oxide A412 is used to absorb VOC. The heating plates and heating strips are made of iron material, and the first coil A210 is passed through an alternating current to generate an alternating magnetic field, so that the heating plates A130 generate heat through the alternating magnetic field to heat the aluminum oxide.

[0035] The top of the inner box A120 is connected to one end of the first access pipe A151, the second access pipe A152, and the third access pipe A153, respectively, and the bottom of the inner box A120 is connected to one end of the first access pipe A141, the second access pipe A142, and the third access pipe A143, respectively;

[0036] The air inlet pipe 110 is connected to the inlet of the first reversing valve A211, and the first outlet and the second outlet of the first reversing valve A211 are respectively connected to the other end of the first sub-access pipes A151 of the two alumina adsorption tanks, and when in use, the first reversing valve A211 is used to selectively connect its inlet with one of the first sub-access pipes A151, thereby transporting the heat exchange gas discharged from the heat exchanger 150 to one of the alumina adsorption tanks.

[0037] The first access pipe A141 is connected to the inlet of the first check valve A221, and the outlet of the first check valve A221 is connected to the exhaust pipe 120, so that the treated gas is output. The second secondary access pipe A152 is connected to the inlet of the fourth check valve A224, and the outlet of the fourth check valve A224 is connected to the condensation inlet of the condenser A250, and the condensation outlet of the condenser A250 is connected to the inlet of the storage tank A260, so that the condensed water is returned to the storage tank A260 for storage.

[0038] The second access pipe A142 is connected to the inlet of the second one-way valve A222, and the outlet of the second one-way valve A222 is connected to the inlet of the storage tank A260, so that the liquid during hydrolysis flows into the storage tank A260 for storage.

[0039] The third secondary access pipe A153 is connected to the inlet of the third one-way valve A223, and the outlet of the third one-way valve A223 is connected to the condensation inlet of the condenser A250, so that the water vapor during drying is condensed, and the condensed gas is directly discharged or input into the air intake pipe 110 for further processing;

[0040] The other ends of the third access pipe A143 of the two alumina adsorption tanks are respectively connected to the first outlet and the second outlet of the second reversing valve A212, and the inlet of the second reversing valve A212 is connected to the outlet of the steam pump A273. The steam pump A273 belongs to the steam system, and the steam system also includes a booster water pump A271. The inlet of the booster water pump A271 is connected to the water source, and the outlet is connected to the inlet of the atomizer A272. The atomizer A272 is used to atomize water, and the outlet of the atomizer A272 is connected to the first inlet of the third reversing valve A213. The second inlet of the third reversing valve A213 is connected to the external air source (atmosphere), and the outlet of the third reversing valve A213 is connected to one end of the heating gap A333 of the heater A300. The third reversing valve A213 is used to select one of its first inlet and second inlet to be connected to its outlet;

[0041] The heater A300 includes a first shell A310 and a second shell A320, wherein an installation gap A311 is formed between the first shell A310 and the second shell A320, wherein a second coil A280 is installed in the installation gap A311, and the installation gap A311 is filled with heat insulation cotton A420, wherein a first heating baffle A331 and a second heating baffle A332 are staggeredly installed in the second shell A320, wherein a heating gap A333 is formed between the first heating baffle A331 and the second heating baffle A332, and the other end of the heating gap A333 is connected to the inlet of the steam pump A273;

[0042] The first heating baffle A331 and the second heating baffle A332 are made of iron material. An alternating current is passed through the second coil to generate an alternating magnetic field. The alternating magnetic field causes the first heating baffle A331 and the second heating baffle A332 to generate heat, and the generated heat heats the atomized water vapor to quickly turn it into water vapor, which is then output to the second reversing valve A212 through the steam pump A273. The second reversing valve A212 is selectively connected to one of the third access pipes A143.

[0043] In this embodiment, when in use, the first reversing valve connects the intake pipe 110 with the first auxiliary access pipe A151 of the left alumina adsorption tank. The airflow enters the alumina adsorption tank and is filtered. It is then discharged to the exhaust pipe 120 through the first access pipe A141 and the first one-way valve A221 and then delivered to the compressor for compression.

[0044] When this alumina adsorption tank needs to be hydrolyzed, the first reversing valve A211 cuts off the connection with the first sub-access pipe A151 of this alumina adsorption tank, and connects with the first sub-access pipe A151 of another alumina adsorption tank (the alumina adsorption tank on the right); then the airflow is processed through this right alumina adsorption tank and discharged to the compressor or the next-stage adsorption device.

[0045] At the same time, the second reversing valve connects its inlet with the third access pipe A143 of the alumina adsorption tank on the left, and the booster pump A271, the second coil A280, the first coil A210, the steam pump A273, and the condenser A250 are all powered on and started. The booster pump A271 pressurizes the water and inputs it into the atomizer to be atomized into water mist, and then enters the heating gap A333 under the negative pressure generated by the steam pump A273 on the heating gap A333. The first heating baffle A331 and the second heating baffle A332 are heated respectively, and then the water mist is heated by self-generated heat, so that the water mist quickly becomes high-temperature water vapor, and then enters the steam pump A273. The steam pump A273 flushes the alumina with the high-temperature water vapor and is filled with water to hydrolyze the VOC adsorbed therein. The liquid produced during the hydrolysis flows into the storage tank A260 through the second access pipe A142, and the gases produced during the hydrolysis enter the condensers respectively. After condensation, the gas is discharged to the exhaust gas treatment device for treatment, and the liquid is input to the storage tank for storage. During this process, the alternating magnetic field generated by the first coil heats the heating plate, and the heating plate quickly heats the aluminum oxide and aluminum fluoride mixture to 300-400° C., so that the aluminum fluoride can be quickly hydrolyzed by water vapor.

[0046] After the hydrolysis of water vapor is completed, the external gas source of the third reversing valve A213 is connected to the heating gap A333, and the atomizer A272 is disconnected from the heating gap. Then the steam pump is started to pump the external gas to the heating gap and heat it into high-temperature gas. The high-temperature gas dries the alumina. After drying, the booster water pump A271, the second coil A280, the first coil A210, the steam pump A273, and the condenser A250 stop running respectively, thereby completing the hydrolysis. The alumina adsorption tank after hydrolysis enters the standby state, and this cycle repeats.

[0047] This design enables the present invention to achieve uninterrupted operation to increase production and reduce costs, and the hydrolysis of aluminum fluoride can increase the service life of alumina, thereby reducing solid waste and reducing use costs.

[0048] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

[0049] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A condensation recovery device for tail gas containing hydrogen fluoride and hydrogen chloride, characterized in that: It includes a liquid nitrogen condenser, which is used to condense the waste gas. The air inlet of the liquid nitrogen condenser is connected with the waste gas, the air outlet is connected with the inlet of the adsorption device or the compressor, and the liquid outlet of the liquid nitrogen condenser is connected with the inlet of the storage tank, so that the liquid HF condensed by the liquid nitrogen condenser is input into the storage tank for storage. The adsorption device is used to adsorb HF in the gas, and the high-purity HCL is compressed into the gas cylinder by the compressor to obtain high-purity cylinder gas; The compressor is used to compress gaseous HCL, and then store it in gas cylinders to obtain industrial-grade cylinder gas; The adsorption device includes two alumina adsorption tanks, one of which is used selectively, and the alumina adsorption tank includes an outer box and an inner box, the inner box is installed inside the outer box and a heat preservation gap is formed between the inner box and the inner wall of the outer box, and a first coil is installed in the heat preservation gap; At least two heating plates are fixed in the inner box, and the heating plates are provided with air holes and heating strips, and the inner box is filled with alumina, which is used to adsorb VOCs; the top of the inner side of the inner box is connected to one end of the first access pipe, the second access pipe, and the third access pipe, respectively, and the bottom of the inner box is connected to one end of the first access pipe, the second access pipe, and the third access pipe, respectively; The air inlet pipe is connected to the inlet of the first reversing valve, and the first outlet and the second outlet of the first reversing valve are respectively connected to the other end of the first secondary access pipes of the two alumina adsorption tanks, and when in use, the first reversing valve is used to selectively connect its inlet to one of the first secondary access pipes; the first access pipe is connected to the inlet of the first one-way valve, and the outlet of the first one-way valve is connected to the exhaust pipe, so as to output the treated gas.

2. The condensation recovery device for tail gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 1, characterized in that: The second secondary access pipe is connected to the inlet of the fourth one-way valve, the outlet of the fourth one-way valve is connected to the condensation inlet of the condenser, and the condensation outlet of the condenser is connected to the inlet of the storage tank; the second access pipe is connected to the inlet of the second one-way valve, and the outlet of the second one-way valve is connected to the inlet of the storage tank; the third secondary access pipe is connected to the inlet of the third one-way valve, and the outlet of the third one-way valve is connected to the condensation inlet of the condenser.

3. The condensation recovery device for tail gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 2, characterized in that: The other ends of the third access pipes of the two alumina adsorption tanks are respectively connected to the first outlet and the second outlet of the second reversing valve, the inlet of the second reversing valve is connected to the outlet of the steam pump, the steam pump belongs to the steam system, and the steam system also includes a booster water pump, the inlet of the booster water pump is connected to the water source, and the outlet is connected to the inlet of the atomizer, the atomizer is used to atomize water, and the outlet of the atomizer is connected to the first inlet of the third reversing valve, the second inlet of the third reversing valve is connected to the external air source, the outlet of the third reversing valve is connected to one end of the heating gap of the heater, and the third reversing valve is used to select one of its first inlet and second inlet to be connected to its outlet; The heater comprises a first shell and a second shell, a mounting gap is formed between the first shell and the second shell, a second coil is installed in the mounting gap, a first heating baffle and a second heating baffle arranged alternately are installed in the second shell, a heating gap is formed between the first heating baffle and the second heating baffle, and the other end of the heating gap is connected to the inlet of the steam pump; The first heating baffle and the second heating baffle are made of iron material, an alternating current is passed through the second coil, and the second reversing valve is selectively connected to one of the third access pipes.

4. The condensation recovery device for tail gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 3, characterized in that: The insulation gap is filled with insulation material; the installation gap is filled with insulation cotton.

5. The process for condensing and recovering tail gas containing hydrogen fluoride and hydrogen chloride obtained by the tail gas condensing and recovering device containing hydrogen fluoride and hydrogen chloride according to any one of claims 1 to 4, characterized in that: The steps include: S1. Input the waste gas of mixed oil HF and HCL into the liquid nitrogen condenser, and cool the waste gas to -98℃ through the liquid nitrogen condenser. Make HF liquefy and HCL remain in gaseous state; S2. Output the liquid phase for storage and output the separated gas for further processing.

6. The condensation recovery process of tail gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 5, characterized in that: in S2, the separated gas is input into a compressor, compressed and bottled to obtain industrial-grade HCL cylinder gas.

7. The process for condensing and recovering tail gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 5, characterized in that: in S2, the separated gas is adsorbed by a multi-stage alumina adsorption tank to obtain high-purity HCL, thereby obtaining high-purity HCL gas.

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