System for recovering HF (hydrogen fluoride) in nitrogen trifluoride electrolyte batching and storage emptying tail gas
By designing the HF recovery system in the exhaust exhaust gas of the nitrogen trifluoride electrolyte batching and storage, the combination of buffer tank, condensation tower, absorption tower, water washing tower and alkali washing tower, combined with the low-temperature crystallization process, the problems of large cooling consumption and low economic value of HF recovery in nitrogen trifluoride production are solved, and efficient recovery of HF and the improvement of economic value are achieved.
Patent Information
- Application Number
- CN202422168884.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-09-05
AI Technical Summary
In the existing nitrogen trifluoride production process, the HF recycling process has problems such as high cooling consumption and low recycling economic value.
A HF recovery system for nitrogen trifluoride electrolyte batching and storage vented exhaust exhaust gas is designed. Through the combination of buffer tank, condensation tower, absorption tower, water washing tower and alkali washing tower, it is absorbed by ammonia water or ammonium fluoride aqueous solution, and combined with low-temperature crystallization technology, the efficient recovery of HF is achieved.
The efficient recycling of HF and the improvement of economic value have been achieved, which significantly improves the economic value of HF in the production exhaust gas, simplifies the process flow, and reduces energy consumption.
Smart Images
Figure CN223127661U_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of hydrogen fluoride (HF) tail gas treatment in fluorine chemical industry, and specifically relates to a process system for recovering HF from the tail gas of trifluoride nitride electrolyte batching and storage discharging. Background Art
[0002] As an excellent plasma etching gas, trifluoride nitride is widely used in the microelectronics industry. With the large-scale development of the electronics industry, the demand for trifluoride nitride will increase day by day. At present, the domestic production process of trifluoride nitride mainly uses the molten salt electrolysis method of ammonium bifluoride for large-scale production. During the production process of trifluoride nitride, a large amount of waste gas containing hydrogen fluoride is generated. The volatilization of a large amount of hydrogen fluoride not only causes waste of production raw materials and increases production costs, but also increases the burden of waste gas treatment. Often, a complex absorption system is required to absorb hydrogen fluoride to make the tail gas containing HF meet the emission standards.
[0003] Hydrogen fluoride HF, with a molecular weight of 20.008. Its aqueous solution is hydrofluoric acid. Under normal pressure, hydrogen fluoride is a colorless, irritating gas when the temperature is higher than 19.51 °C, emits fumes in the air, and has hygroscopicity. A large amount of hydrogen fluoride is consumed during the production process of trifluoride nitride. However, due to the relatively high reaction temperature during the trifluoride nitride electrolysis process and batching process, a large amount of HF will volatilize and be discharged along with the waste gas. In order to make the gas meet the emission standards, it is necessary to treat and recover the hydrogen fluoride in the waste gas. At present, the main HF recovery processes in the trifluoride nitride batching and the cathode venting system of the electrolytic cell are the method of recovering hydrogen fluoride by low-temperature condensation and washing with water to recover hydrofluoric acid and the process of washing with water and alkali to absorb hydrogen fluoride. The problems existing in these methods are: (1) A large amount of cooling capacity is required for cooling during the recovery process; (2) Part of the hydrogen fluoride is recovered in the form of hydrofluoric acid after washing with water, and the economic value is relatively low. Summary of the Invention
[0004] The purpose of this patent is to overcome the problems of large cooling capacity consumption and low recovery economic value existing in the prior art, and provide a process system for recovering HF from the tail gas of trifluoride nitride electrolyte batching and storage discharging. This system has a simple process and relatively high recovery economic value.
[0005] To achieve the above object, the present utility model is implemented as follows: A nitrogen trifluoride electrolyte batching and HF recovery system for the tail gas of storage and venting. A buffer tank 2, a condensation tower 3, an absorption tower 4, a water washing tower 5, and an alkali washing tower 6 are sequentially connected by pipelines; A main pipeline 1 is inserted into the bottom of the buffer tank 2, and the top of the buffer tank 2 is connected to the middle of the condensation tower 3; The top of the condensation tower 3 is connected to the middle of the absorption tower 4, and the bottom of the condensation tower 3 is connected to a hydrogen fluoride collection tank 7; The top of the absorption tower 4 is connected to the middle of the water washing tower 5, the bottom of the absorption tower 4 is connected to an absorption liquid storage tank 8, and the outlet end of the absorption liquid storage tank 8 is connected to a first circulation pump 101. The outlet of the first circulation pump 101 is respectively connected to an absorption tower spray head and an ammonium bifluoride crystallization kettle 9; The top of the water washing tower 5 is connected to the middle of the alkali washing tower 6, the bottom of the water washing tower 5 is connected to a second circulation pump 102, and the outlet of the second circulation pump 102 is respectively connected to the absorption tower 4 spray head and the water washing tower 5 spray head; The bottom of the alkali washing tower 6 is connected to a third circulation pump 103, and the outlet of the third circulation pump 103 is connected to an alkali washing tower spray head.
[0006] Further, the buffer tank 2 is provided with a cooling coil.
[0007] Further, the ammonium bifluoride crystallization kettle 9 has a crystallization liquid outlet, and the crystallization liquid outlet is connected to subsequent filtration and separation equipment.
[0008] Further, valves are connected to the pipelines between the second circulation pump 102 and the absorption tower 4 spray head, and between the second circulation pump 102 and the water washing tower 5 spray head, enabling the switching of two-way liquids.
[0009] Further, the absorption tower 4 is filled with ammonia water or an ammonium fluoride aqueous solution.
[0010] Further, the top of the alkali washing tower 6 is connected to an external venting tower for discharge.
[0011] Further, the absorption tower 4 is provided with a cooling jacket or a cooling coil; The absorption liquid storage tank 8 is provided with a cooling jacket or a cooling coil.
[0012] The present utility model provides a nitrogen trifluoride electrolyte batching and HF recovery system for the tail gas of storage and venting. The HF waste gas in the nitrogen trifluoride electrolyte batching and the tail gas of storage and venting is preliminarily cooled and dust-removed through a buffer tank. The HF-containing gas after preliminary cooling is introduced into a condenser for condensation. The condensed HF enters the hydrogen fluoride collection tank for collection and standby. The non-condensable gas is introduced into an absorption tower filled with ammonia water or an ammonium fluoride aqueous solution for an absorption reaction to obtain a mixed solution containing hydrogen fluoride and ammonium bifluoride. The mixed solution is introduced into a crystallization kettle for evaporation concentration and low-temperature crystallization to obtain ammonium bifluoride. The setting of the water washing tower and the alkali washing tower ensures the up-to-standard discharge of the gas. The present utility model not only realizes the reuse of HF in the electrolyte batching and the gas system of storage and venting air in the production of nitrogen trifluoride, but also realizes the production of ammonium bifluoride with a higher economic value from part of the hydrogen fluoride, significantly improving the economic value of HF in the production tail gas. Brief Description of the Drawings
[0013] Figure 1 It is a schematic diagram of an HF recovery system for nitrogen trifluoride electrolyte batching and storage bin venting tail gas.
[0014] Wherein: 1. Main pipeline; 2. Buffer tank; 3. Condensation tower; 4. Absorption tower; 5. Water washing tower; 6. Alkali washing tower; 7. Hydrogen fluoride collection tank; 8. Absorbent storage tank; 9. Ammonium bifluoride crystallization kettle; 101. First circulation pump; 102. Second circulation pump; 103. Third circulation pump Detailed Implementation Modes
[0015] For the convenience of understanding the present utility model, the following are examples of the present utility model. Those skilled in the art should understand that the said examples are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.
[0016] Example 1
[0017] As Figure 1 shown, an HF recovery system for nitrogen trifluoride electrolyte batching and storage bin venting tail gas, the buffer tank 2, the condensation tower 3, the absorption tower 4, the water washing tower 5, and the alkali washing tower 6 are sequentially connected through pipelines; the main pipeline 1 is inserted into the bottom of the buffer tank 2, and the top of the buffer tank 2 is connected to the middle part of the condensation tower 3; the top of the condensation tower 3 is connected to the middle part of the absorption tower 4, and the bottom of the condensation tower 3 is connected to the hydrogen fluoride collection tank 7; the top of the absorption tower 4 is connected to the middle part of the water washing tower 5, the bottom of the absorption tower 4 is connected to the absorbent storage tank 8, the outlet end of the absorbent storage tank 8 is connected to the first circulation pump 101, and the outlet of the first circulation pump 101 is respectively connected to the spray head of the absorption tower and the ammonium bifluoride crystallization kettle 9; the top of the water washing tower 5 is connected to the middle part of the alkali washing tower 6, the bottom of the water washing tower 5 is connected to the second circulation pump 102, and the outlet of the second circulation pump 102 is respectively connected to the spray head of the absorption tower 4 and the spray head of the water washing tower 5; the bottom of the alkali washing tower 6 is connected to the third circulation pump 103, and the outlet of the third circulation pump 103 is connected to the spray head of the alkali washing tower.
[0018] The buffer tank 2 is provided with a cooling coil to control the temperature of the gas at 20 - 60°C.
[0019] The ammonium bifluoride crystallization kettle 9 has a crystallization liquid outlet, and the crystallization liquid outlet is connected to subsequent filtration and separation equipment.
[0020] Valves are installed on the pipelines between the second circulation pump 102 and the spray head of the absorption tower 4 and between the second circulation pump 102 and the spray head of the water washing tower 5, so as to realize the switching of the two-way liquid.
[0021] The absorption tower 4 is filled with ammonia water or ammonium fluoride aqueous solution. The ammonia water can be prepared by introducing ammonia gas into the absorption tower 4. Both the absorption tower 4 and the absorbent storage tank 8 are provided with cooling jackets or cooling coils, and the temperature is controlled at 20 - 40°C.
[0022] The top of the caustic scrubber 6 is connected to the external vent tower for discharge.
[0023] The refrigerant of the condensation tower 3 is process residual cold or low-temperature nitrogen, and the temperature is controlled at -15 to 10 °C.
[0024] The solid-liquid mixture of the absorption liquid after concentration by evaporation and low-temperature cooling crystallization in the ammonium bifluoride crystallization kettle 9 is filtered and separated, and the filtrate is returned to the ammonium bifluoride crystallization kettle 9 as the crystallization mother liquor, and the evaporated condensate is returned to the water scrubber for reuse.
[0025] The water scrubbing liquid of the water scrubber 5 supplements the absorption liquid of the absorption tower 4 after the absorption liquid of the absorption tower is discharged into the ammonium bifluoride crystallization kettle 9, and ammonia gas is introduced into the supplemented absorption liquid to adjust the ammonia water concentration of the absorption liquid to 20% - 30%.
[0026] The recovery process of this system is as follows:
[0027] The vent tail gas generated by the nitrogen trifluoride electrolyte batching system first converges into the main pipeline 1 and enters the buffer tank 2. At the same time, the low-temperature circulating water enters from the inlet of the cooling coil and flows out from the outlet to achieve tail gas dust removal and cooling, and the temperature drops to 30 °C; the preliminarily cooled tail gas enters the condensation tower 3. At the same time, the low-temperature refrigerant enters from the inlet of the cooling coil in the condensation tower 3 and flows out from the outlet of the cooling coil, and the temperature drops to -15 - 10 °C. The condensed hydrogen fluoride is stored in the hydrogen fluoride collection tank 7 for standby; the non-condensable gas after condensation and absorption enters the absorption tower 4, and the absorption liquid is 25% ammonia water. During the absorption process, the temperatures of the absorption tower 4 and the absorption liquid storage tank 8 are controlled at 20 - 40 °C. When the ammonium bifluoride concentration of the absorption liquid reaches 30%, the absorption liquid is transferred to the ammonium bifluoride crystallization kettle 9 for evaporation. When the ammonium bifluoride concentration reaches 55%, low-temperature crystallization is carried out. The solid-liquid mixture after crystallization is filtered and separated, the mother liquor is returned to the ammonium bifluoride crystallization kettle 9, and the crystals are dried to obtain ammonium bifluoride for re-preparing the electrolyte. The condensate obtained by evaporation condensation is introduced into the water scrubber 5, and the water scrubbing liquid in the water scrubber 5 supplements the absorption tower 4 and then ammonia gas is introduced to prepare a 25% ammonia water solution; the absorbed gas passes through the water scrubber 5 and the caustic scrubber 6 again, and after the gas meets the standards, it is discharged.
[0028] Example 2
[0029] The HF recovery system for the nitrogen trifluoride electrolyte batching and storage vent tail gas is the same as that in Example 1.
[0030] The recovery process of this system is as follows:
[0031] The vent gas from the nitrogen trifluoride electrolyte storage tank first converges into the main pipeline 1 and enters the buffer tank 2, where the temperature drops to 25°C; the tail gas after preliminary cooling enters the condensation tower 3, where the temperature drops to -10°C in the condensation tower 3, and the condensed and liquefied hydrogen fluoride is stored in the hydrogen fluoride collection tank 7 for standby; the non-condensable gas after condensation and absorption enters the absorption tower 4, and the absorption liquid is 20% ammonia water. During the absorption process, the temperature of the absorption tower 4 and the absorption liquid storage tank 8 is controlled at 25°C. When the ammonium bifluoride concentration in the absorption liquid reaches 35%, the absorption liquid is transferred to the ammonium bifluoride crystallization kettle 9 for evaporation. When the ammonium bifluoride concentration reaches 60%, low-temperature crystallization is carried out. After the crystallization is completed, the solid-liquid mixture is filtered and separated by a centrifuge. The mother liquor returns to the ammonium bifluoride crystallization kettle 9, and the crystals are dried to obtain ammonium bifluoride. The condensate obtained from evaporation and condensation is introduced into the water washing tower 5, and the washing liquid in the water washing tower 5 replenishes the absorption tower 4 and then ammonia gas is introduced to prepare 20% ammonia water solution; the absorbed gas then passes through the water washing tower 5 and the alkali washing tower 6, and after the gas meets the standards, it is discharged.
[0032] Example 3
[0033] The HF recovery system for the nitrogen trifluoride electrolyte batching and storage vent gas is the same as that in Example 1.
[0034] The recovery process of this system is as follows:
[0035] The vent gas generated by the nitrogen trifluoride electrolyte batching system and the storage system first converges into the main pipeline 1 and enters the buffer tank 2, where the temperature drops to 30°C; the tail gas after preliminary cooling enters the condensation tower 3, where the temperature drops to -5°C in the condensation tower 3, and the condensed and liquefied hydrogen fluoride is stored in the hydrogen fluoride collection tank 7 for standby; the non-condensable gas after condensation and absorption enters the absorption tower 4, and the absorption liquid is 15% ammonium fluoride aqueous solution. During the absorption process, the temperature of the absorption tower 4 and the absorption liquid storage tank 8 is controlled at 20°C. When the ammonium bifluoride concentration in the absorption liquid reaches 25%, the absorption liquid is transferred to the ammonium bifluoride crystallization kettle 9 for evaporation. When the ammonium bifluoride concentration reaches 65%, low-temperature crystallization is carried out. After the crystallization is completed, the solid-liquid mixture is filtered and separated by a centrifuge. The mother liquor returns to the ammonium bifluoride crystallization kettle 9, and the crystals are dried to obtain ammonium bifluoride. The condensate obtained from evaporation and condensation is introduced into the water washing tower 5, and the washing liquid in the water washing tower 5 replenishes the absorption tower 4 and then ammonia gas is introduced to prepare 15% ammonium fluoride aqueous solution; the absorbed gas then passes through the water washing tower 5 and the alkali washing tower 6, and after the gas meets the standards, it is discharged.
[0036] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in this description can be different and are not limited. Therefore, those skilled in the art of the present invention can modify or equivalently replace the technical solutions recorded in the foregoing embodiments; and these modifications and replacements do not depart from the spirit and technical solutions of the present invention, and should all fall within the protection scope of the present invention.
Claims
1. A nitrogen trifluoride electrolyte batching and HF recovery system for the tail gas of storage and venting, characterized in that, The buffer tank (2), the condensation tower (3), the absorption tower (4), the water washing tower (5), and the alkali washing tower (6) are connected in sequence through pipelines; the main pipeline (1) is inserted into the bottom of the buffer tank (2), and the top of the buffer tank (2) is connected to the middle part of the condensation tower (3); the top of the condensation tower (3) is connected to the middle part of the absorption tower (4), and the bottom of the condensation tower (3) is connected to the hydrogen fluoride collection tank (7); the top of the absorption tower (4) is connected to the middle part of the water washing tower (5), the bottom of the absorption tower (4) is connected to the absorption liquid storage tank (8), the outlet end of the absorption liquid storage tank (8) is connected to the first circulation pump (101), and the outlet of the first circulation pump (101) is respectively connected to the absorption tower spray head and the ammonium bifluoride crystallization kettle (9); the top of the water washing tower (5) is connected to the middle part of the alkali washing tower (6), the bottom of the water washing tower (5) is connected to the second circulation pump (102), and the outlet of the second circulation pump (102) is respectively connected to the absorption tower (4) spray head and the water washing tower (5) spray head; the bottom of the alkali washing tower (6) is connected to the third circulation pump (103), and the outlet of the third circulation pump (103) is connected to the alkali washing tower spray head.
2. The nitrogen trifluoride electrolyte batching and HF recovery system for the storage and venting tail gas according to claim 1, wherein, The buffer tank (2) is provided with a cooling coil.
3. The nitrogen trifluoride electrolyte batching and HF recovery system for the storage and venting tail gas according to claim 1, wherein The ammonium bifluoride crystallization kettle (9) has a crystallization liquid outlet, and the crystallization liquid outlet is connected to subsequent filtration and separation equipment.
4. The nitrogen trifluoride electrolyte batching and HF recovery system for the storage and venting tail gas according to claim 1, wherein Valves are provided on the pipeline between the second circulation pump (102) and the absorption tower (4) spray head, and valves are provided on the pipeline between the second circulation pump (102) and the water washing tower (5) spray head.
5. The NF₃ electrolyte batching and HF recovery system for the storage and venting tail gas according to claim 1, wherein The absorption tower (4) is filled with ammonia water or an aqueous solution of ammonium fluoride.
6. The nitrogen trifluoride electrolyte batching and HF recovery system for the tail gas of storage and venting according to claim 1, wherein The top of the alkali washing tower (6) is connected to an external vent tower for discharge.