Low-temperature distillation purification device for mixed acid containing hydrofluoric acid

Abstract

The utility model provides a low-temperature distillation purification device for mixed acid containing hydrofluoric acid. The low-temperature distillation purification device comprises a distillation tank, a first shell-and-tube condenser, a second shell-and-tube condenser, an absorption tower, a storage tank, a two-stage heat pump, a dry vacuum pump and a jet vacuum pump, a mixed acid circulation pipeline is arranged among the distillation retort, the first shell-and-tube condenser, the second shell-and-tube condenser and the absorption tower, a condensation pipeline is arranged among the first shell-and-tube condenser, the second shell-and-tube condenser and the two-stage heat pump, and a heating pipeline is arranged between a heating assembly of the distillation retort and the two-stage heat pump; the outer sides of the inner cavities of the distillation retort, the first shell-and-tube condenser, the storage tank and the absorption tower are respectively provided with a vacuum interlayer cavity, and the side walls of the inner cavities of the distillation retort, the first shell-and-tube condenser, the storage tank and the absorption tower are respectively lined with a fluorine layer. The purification device can realize efficient purification and collection of mixed acid, and is low in energy consumption and long in service life.

Description

Technical Field

[0001] The utility model relates to the technical field of mixed acid purification, in particular to a low-temperature distillation purification device for mixed acids containing hydrofluoric acid. Background Art

[0002] The high-purity silicon and chip industries often use mixed acids containing hydrofluoric acid, nitric acid, sulfuric acid, and hydrochloric acid to remove oxides from product surfaces. The booming chip industry has led to a gradual increase in the consumption of mixed acids. Because mixed acids are highly corrosive to equipment and containers, recycling waste acids is difficult and expensive.

[0003] At present, some factories use Teflon equipment to distill and purify waste acid. Although Teflon is used to achieve corrosion resistance, due to the strength of the material, it is impossible to use high vacuum and low pressure distillation technology to purify the waste acid. At the same time, most equipment has high energy consumption during operation, low output and short equipment life. Utility Model Content

[0004] The purpose of the utility model is to provide a low-temperature distillation and purification device for a mixed acid containing hydrofluoric acid. The distillation and purification process can achieve high-vacuum, low-temperature distillation of the mixed acid, thereby reducing the energy consumption of waste acid treatment and increasing the waste acid purification output; at the same time, by utilizing the vacuum balance principle, the fluorine layer of the inner lining in the corresponding equipment can be effectively prevented from falling off, thereby increasing the service life of the equipment.

[0005] The technical solution adopted by the utility model to solve the technical problem is: a low-temperature distillation and purification device for mixed acid containing hydrofluoric acid, comprising a distillation tank, a first shell and tube condenser, a second shell and tube condenser, an absorption tower, a storage tank, a two-stage heat pump, a dry vacuum pump, and a jet vacuum pump; a mixed acid circulation pipeline is provided between the distillation tank, the first shell and tube condenser, the second shell and tube condenser and the absorption tower, the storage tank is used to collect condensed water flowing out of the first shell and tube condenser, a condensation pipeline is provided between the first shell and tube condenser, the second shell and tube condenser and the two-stage heat pump, and the two-stage heat pump can It is capable of cooling the circulating medium in the condensing pipeline. A heating pipeline is provided between the heating component of the distillation tank and the two-stage heat pump. The two-stage heat pump can heat the circulating medium in the heating pipeline. A vacuum interlayer cavity is provided on the outside of the inner cavity of the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower. The vacuum interlayer cavity is connected with the air inlet end of the dry vacuum pump through a vacuum pipeline. The air inlet end of the jet vacuum pump is connected with the inner cavity of the absorption tower. The side walls of the inner cavity of the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower are lined with a fluorine layer.

[0006] Preferably, the mixed acid circulation pipeline includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a fifth pipeline, and a first circulation pump. The first pipeline realizes a through connection between the upper outlet of the inner cavity of the distillation tank and the shell side inlet of the first shell and tube condenser. The second pipeline realizes a through connection between the shell side gas outlet of the first shell and tube condenser and the tube side inlet of the second shell and tube condenser. The feed ends of the third pipeline and the fourth pipeline are through-connected with the tube side outlet of the second shell and tube condenser in parallel. The discharge end of the third pipeline is through-connected with the upper part of the inner cavity of the absorption tower. The liquid outlet end of the fourth pipeline is through-connected with the bottom of the inner cavity of the absorption tower. The fifth pipeline realizes a through connection between the spray inlet of the absorption tower and the bottom of the inner cavity of the absorption tower. The first circulation pump is connected in series to the fifth pipeline.

[0007] Furthermore, the condensation pipeline includes a sixth pipeline, a seventh pipeline, an eighth pipeline, and a second circulation pump. The sixth pipeline realizes a through connection between the liquid outlet end of the cooling side of the two-stage heat pump and the tube side inlet of the first shell and tube condenser. The seventh pipeline realizes a through connection between the tube side outlet of the first shell and tube condenser and the shell side inlet of the second shell and tube condenser. The eighth pipeline realizes a through connection between the shell side outlet of the second shell and tube condenser and the liquid inlet end of the cooling side of the two-stage heat pump. The second circulation pump is connected in series to the eighth pipeline.

[0008] Furthermore, the heating pipeline includes a ninth pipeline, a tenth pipeline, and a third circulation pump. The ninth pipeline realizes a through connection between the liquid outlet end of the heating side of the two-stage heat pump and the inlet end of the heating component. The tenth pipeline realizes a through connection between the liquid inlet end of the heating side of the two-stage heat pump and the outlet end of the heating component. The third circulation pump is connected in series to the ninth pipeline.

[0009] Furthermore, the heating component is a spiral sleeve.

[0010] Furthermore, the vacuum pipeline includes an eleventh pipeline, a twelfth pipeline, a thirteenth pipeline, a fourteenth pipeline, and a fifteenth pipeline; the air inlet end of the eleventh pipeline is connected to the vacuum interlayer cavity of the distillation tank, the air inlet end of the twelfth pipeline is connected to the vacuum interlayer cavity of the first shell and tube condenser, the air inlet end of the thirteenth pipeline is connected to the vacuum interlayer cavity of the storage tank, and the air outlet ends of the eleventh pipeline, the twelfth pipeline and the thirteenth pipeline are connected in parallel to the fourteenth pipeline. The inlet end of the absorption tower is connected in a through-connection manner, the fifteenth pipeline realizes the through-connection between the vacuum interlayer cavity of the absorption tower and the air inlet of the dry vacuum pump, the outlet end of the fourteenth pipeline is connected in a through-connection manner with the fifteenth pipeline, the inlet end of a sixteenth pipeline is connected in a through-connection manner with the outlet end of the dry vacuum pump, the inlet end of a seventeenth pipeline is connected in a through-connection manner with the bottom of the inner cavity of the absorption tower, and the outlet ends of the sixteenth pipeline and the seventeenth pipeline are connected in parallel with the inlet end of the jet vacuum pump.

[0011] Furthermore, an eighteenth pipeline realizes a through-connection between the shell-side liquid outlet of the first shell and tube condenser and the inner cavity of the storage tank.

[0012] The beneficial effects of the utility model are as follows: the system of the utility model is simple in composition and easy to process and manufacture; the inner cavity of the distillation tank can be in a vacuum environment, which can reduce the boiling point of the waste acid therein, thereby facilitating the effective separation of various acids and water in the mixed acid, and providing a guarantee for the subsequent purification of the waste acid; the inner cavities of the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower are all lined with a fluorine layer, which has corrosion resistance and can greatly improve the service life of the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower; the dry vacuum pump and the jet vacuum pump can be used to realize the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower. The vacuum balance between the vacuum interlayer cavity and the inner cavity in the shell condenser, storage tank and absorption tower can effectively prevent the fluorine layer from bulging, improve the adhesion effect of the fluorine layer on the side wall of the inner cavity, and then effectively extend the service life of the fluorine layer; the use of a two-stage heat pump can use the heat energy released by the cooling medium as the heat source of the heating component, thereby improving the thermal energy utilization rate and reducing energy consumption; the through connection between the outlet end of the dry vacuum pump and the inlet end of the jet vacuum pump can maintain the vacuum degree of the vacuum interlayer cavity after the dry vacuum pump fails, thereby effectively preventing the bulging of the inner lining fluorine layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 This is the system principle diagram of the utility model;

[0015] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0016] In the figure: 1 distillation tank, 11 heating component, 2 first shell and tube condenser, 3 second shell and tube condenser, 4 absorption tower, 5 storage tank, 6 two-stage heat pump, 7 dry vacuum pump, 8 jet vacuum pump, 101 first circulation pump, 102 second circulation pump, 103 third circulation pump, 201 first pipeline, 202 second pipeline, 203 third pipeline, 204 fourth pipeline, 205 fifth pipeline, 206 sixth pipeline, 207 seventh pipeline, 208 eighth pipeline, 209 ninth pipeline, 210 tenth pipeline, 211 eleventh pipeline, 212 twelfth pipeline, 213 thirteenth pipeline, 214 fourteenth pipeline, 215 fifteenth pipeline, 216 sixteenth pipeline, 217 seventeenth pipeline, 218 eighteenth pipeline, 301 vacuum interlayer chamber, 401 fluorine layer. DETAILED DESCRIPTION

[0017] The following will be combined with specific embodiments and attached Figure 1-2 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the embodiments described are only some preferred embodiments of the present invention, not all embodiments. Those skilled in the art may make similar modifications without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] The utility model provides a low-temperature distillation purification device for mixed acid containing hydrofluoric acid (such as Figure 1As shown), it includes a distillation tank 1, a first shell and tube condenser 2, a second shell and tube condenser 3, an absorption tower 4, a storage tank 5, a two-stage heat pump 6, a dry vacuum pump 7, and a jet vacuum pump 8; the two-stage heat pump 6, the dry vacuum pump 7 and the jet vacuum pump 8 are all mature technology products on the market, so here, the working principle and detailed structure of the two-stage heat pump 6, the dry vacuum pump 7 and the jet vacuum pump 8 are no longer introduced in detail. In this specific embodiment, the two-stage heat pump 6 is used to achieve heat exchange, and the dry vacuum pump 6 and the jet vacuum pump 8 are both used to achieve vacuuming in the corresponding container. A mixed acid is arranged between the distillation tank 1, the first shell and tube condenser 2, the second shell and tube condenser 3 and the absorption tower 4. Circulation pipeline, in actual application, the gaseous mixed substance flowing out of the distillation tank 1 passes through the first shell and tube condenser 2 and the second shell and tube condenser 3 in sequence through the mixed acid circulation pipeline, and finally flows into the absorption tower 4. The storage tank 5 is used to collect the condensed water flowing out of the first shell and tube condenser 2. A condensation pipeline is provided between the first shell and tube condenser 2, the second shell and tube condenser 3 and the two-stage heat pump 4. The low-temperature cooling medium in the condensation pipeline passes through the first shell and tube condenser 2 and the second shell and tube condenser 3 in sequence, and the temperature of the substance circulating therein is reduced. The two-stage heat pump 6 can realize the cooling of the circulating medium in the condensation pipeline. In the heating component 1 of the distillation tank 1 1 and the two-stage heat pump 6 are provided with a heating pipeline, which transfers the heated medium to the heating component 11, and the heating component 11 heats the mixed acid solution in the distillation tank 1. The mixed acid in the distillation tank 1 is transported thereto through a pipeline, and the two-stage heat pump 6 can heat the circulating medium in the heating pipeline; a vacuum interlayer cavity 301 is provided on the outer side of the inner cavity of the distillation tank 1, the first shell and tube condenser 2, the storage tank 3 and the absorption tower 4. The distillation tank 1 is a combination of a mature distillation tank and a vacuum interlayer cavity 301 on the existing market, that is, the distillation tank 1 in this embodiment is based on the existing distillation tank with an external embracing layer, and the embracing layer is connected to the outer wall of the distillation tank. A vacuum interlayer cavity 301 is formed between the first shell and tube condenser 2 and the vacuum interlayer cavity 301, that is, the first shell and tube condenser 2 in this embodiment is a combination of a mature shell and tube condenser on the existing market and a vacuum interlayer cavity 301, that is, an embracing layer is added on the outside of the existing shell and tube condenser, and a vacuum interlayer cavity 301 is formed between the embracing layer and the outer wall of the shell and tube condenser, the storage tank 3 is a combination of a mature storage tank on the market and a vacuum interlayer cavity 301, that is, the storage tank 5 in this embodiment is a combination of a mature storage tank on the market and a vacuum interlayer cavity 301, that is, an embracing layer is added on the outside of the existing storage tank, and a vacuum interlayer cavity 301 is formed between the embracing layer and the outer wall of the storage tank, and the second shell and tube condenser 2 is a mature shell and tube condenser on the existing market;The liquid flow mode in the shell and tube condenser on the existing market is non-contact, that is, the two substances exchange heat without contact. The liquid flow path of the shell and tube condenser is generally divided into shell side and tube side. The shell side is the flow of liquid in the channel between the shell and the pipe, and the tube side is the flow of liquid in the pipe; the vacuum interlayer cavity 301 is connected with the air inlet end of the dry vacuum pump 7 through the vacuum pipeline. The continuous operation of the dry vacuum pump 7 realizes the formation of the vacuum environment in the vacuum interlayer cavity 301. The air inlet end of the jet vacuum pump 8 is connected with the inner cavity of the absorption tower 4. The continuous operation of the jet vacuum pump 8 can realize the distillation tank 1 and the first shell and tube condenser. To create a vacuum environment within the inner cavities of the distillation tank 1, first shell-and-tube condenser 2, storage tank 5, and absorption tower 4, a fluorine layer 401 is lined on the inner sidewalls of the distillation tank 1, first shell-and-tube condenser 2, storage tank 5, and absorption tower 4. Because the inner cavities of the distillation tank 1, first shell-and-tube condenser 2, storage tank 5, and absorption tower 4 are in a vacuum environment, the corresponding vacuum interlayer cavity 301 is also in a vacuum environment, thereby achieving a balance in pressure between the inside and outside of the fluorine layer 401. This balance in pressure between the inside and outside of the fluorine layer 401 effectively prevents bulging of the fluorine layer 401 on the inner sidewalls, thereby increasing the service life of the fluorine layer 401 and thereby improving the service life of the distillation tank 1, first shell-and-tube condenser 2, storage tank 5, and absorption tower 4. In actual applications, to improve the adhesion of the fluorine layer 401 to the corresponding sidewalls, the vacuum degree within the vacuum interlayer cavity 301 can be made greater than the vacuum degree within the corresponding inner cavity, so that the fluorine layer 401 can adhere tightly to the inner sidewalls under the action of atmospheric pressure.

[0019] The distillation tank 1 can provide low-temperature heating and a vacuum environment, thereby reducing the boiling point of the mixed acid and reducing the energy consumption of the mixed acid separation, which is beneficial to improving the separation quality; the first shell and tube condenser 2 and the second shell and tube condenser 3 can be used to condense and cool most of the waste acid, and the gaseous waste acid after cooling is easily absorbed by the absorption tower 4, thereby improving the purification and collection effect of the waste acid. When the first shell and tube condenser 2 is performing condensation, the gaseous waste acid and water vapor go through the shell side, and the partially condensed liquid water and liquid waste acid flow out through the liquid outlet of the shell side of the first tube condenser 2, and the uncondensed water vapor and gaseous waste acid flow out through the shell side air outlet of the first shell and tube condenser 2. When the second shell and tube condenser 3 is performing condensation of the gaseous waste acid, the gaseous waste acid goes through the tube side. Therefore, in order to improve the corrosion resistance of the second shell and tube condenser 3, the pipes in the second shell and tube condenser 3 are made of corrosion-resistant materials.

[0020] On the basis of the above embodiment, the specific implementation of the mixed acid circulation pipeline is as follows: the mixed acid circulation pipeline includes a first pipeline 201, a second pipeline 202, a third pipeline 203, a fourth pipeline 204, a fifth pipeline 205, and a first circulation pump 101, the first pipeline 201 realizes the through connection between the upper outlet of the inner cavity of the distillation tank 1 and the shell-side inlet of the first shell-and-tube condenser 2, and the first pipeline 201 is used to realize the gaseous mixed acid and water vapor from the distillation tank 1 into the first shell-and-tube condenser 2, the second pipeline 202 realizes the through connection between the shell-side gas outlet of the first shell-and-tube condenser 2 and the tube-side inlet of the second shell-and-tube condenser 3, and the uncondensed gaseous water vapor and mixed acid enter the second shell-and-tube condenser 3 through the second pipeline 202 for further condensation and cooling, the third pipeline 203 and the fourth pipeline 204 are connected to each other. The feed end of the fourth pipe 204 is connected in parallel with the tube-side outlet of the second shell and tube condenser 3, the discharge end of the third pipe 203 is connected in parallel with the upper part of the inner cavity of the absorption tower 4, and the uncondensed gaseous water vapor and mixed acid enter the upper part of the inner cavity of the absorption tower 4 through the third pipe 203. The liquid outlet end of the fourth pipe 204 is connected to the bottom of the inner cavity of the absorption tower 4, and the condensed liquid flows into the bottom of the inner cavity of the absorption tower 4 through the fourth pipe 204. The fifth pipe 205 realizes the through connection between the spray inlet of the absorption tower 4 and the bottom of the inner cavity of the absorption tower 4. The first circulation pump 101 is connected in series to the fifth pipe 205, and the continuous operation of the first circulation pump 101 is used to continuously transport the bottom liquid to the spray pipe at the top of the absorption tower 4, thereby facilitating the absorption of the gaseous mixed acid in the absorption tower 4.

[0021] On the basis of the above embodiment, the specific implementation method of the condensing pipeline is as follows: the condensing pipeline includes a sixth pipeline 206, a seventh pipeline 207, an eighth pipeline 208, and a second circulating pump 102, the sixth pipeline 206 realizes the through connection between the liquid outlet end of the cooling side of the two-stage heat pump 6 and the tube side inlet of the first shell and tube condenser 2, and the sixth pipeline 206 is used to realize the transportation of low-temperature medium to the first shell and tube condenser 2, and the seventh pipeline 207 realizes the through connection between the tube side outlet of the first shell and tube condenser 2 and the shell side inlet of the second shell and tube condenser 3, low The warm medium enters the second shell and tube condenser 3 through the seventh pipe 207, and the eighth pipe 208 realizes the through connection between the shell side outlet of the second shell and tube condenser 2 and the liquid inlet end of the cooling side of the two-stage heat pump 6. The second circulation pump 102 is connected in series to the eighth pipe 208. By the continuous operation of the second circulation pump 102, the low-temperature medium flowing out of the two-stage heat pump 6 continuously flows into the first shell and tube condenser 2 and the second shell and tube condenser 3 for heat exchange, thereby realizing the cooling of the flowing material in the first shell and tube condenser 2 and the second shell and tube condenser 3.

[0022] Based on the above embodiment, the heating pipeline is specifically implemented as follows: the heating pipeline includes a ninth pipeline 209, a tenth pipeline 210, and a third circulation pump 103. The ninth pipeline 209 connects the liquid outlet of the heating side of the two-stage heat pump 6 with the inlet of the heating assembly 11. The tenth pipeline 210 connects the liquid inlet of the heating side of the two-stage heat pump 6 with the outlet of the heating assembly. The third circulation pump 103 is connected in series with the ninth pipeline 209. The continuous operation of the third circulation pump 103 allows the high-temperature medium flowing out of the two-stage heat pump 6 to continuously flow into the heating assembly 11 for heat exchange, thereby heating the mixed acid in the distillation tank 1. In actual application, the heating assembly 11 is a spiral sleeve that can be directly spirally mounted on the outer wall of the distillation tank 1 or directly placed in the lower part of the inner cavity of the distillation tank 1.

[0023] On the basis of the above embodiment, the specific implementation of the vacuum pipeline is as follows: the vacuum pipeline includes an eleventh pipeline 211, a twelfth pipeline 212, a thirteenth pipeline 213, a fourteenth pipeline 214, and a fifteenth pipeline 215; the air inlet end of the eleventh pipeline 211 is connected to the vacuum interlayer cavity 301 of the distillation tank 1, the air inlet end of the twelfth pipeline 212 is connected to the vacuum interlayer cavity 301 of the first shell and tube condenser 2, and the air inlet end of the thirteenth pipeline 213 is connected to the vacuum interlayer cavity 301 of the storage tank 5. The outlet ends of the eleventh pipeline 211, the twelfth pipeline 212 and the thirteenth pipeline 213 are connected in parallel with the inlet end of the fourteenth pipeline 214, and the fifteenth pipeline 215 realizes the through connection between the vacuum interlayer cavity 301 of the absorption tower 4 and the air inlet of the dry vacuum pump 7. The outlet end of the fourteenth pipeline 214 is connected in a through connection with the fifteenth pipeline 215. In actual application, when the dry vacuum pump 7 is working, the eleventh pipeline 211, the twelfth pipeline 212, the thirteenth pipeline 213, The permeability of the fourteenth pipeline 214 and the fifteenth pipeline 215 realizes the extraction of air from the corresponding vacuum interlayer cavity 301, thereby forming a vacuum environment in the vacuum interlayer cavity 301. The air inlet end of the sixteenth pipeline 216 is connected to the air outlet end of the dry vacuum pump 7, and the air inlet end of the seventeenth pipeline 217 is connected to the bottom of the inner cavity of the absorption tower 4. The eighteenth pipeline 218 realizes the shell-side liquid outlet of the first shell and tube condenser 2 and the inner cavity of the storage tank 5. The sixteenth pipeline 216 and the seventeenth pipeline are connected to each other. The outlet end of the pipe 217 is connected in parallel with the air inlet end of the jet vacuum pump 8. By utilizing the connection between the mixed acid delivery pipe and the inner cavity of the absorption tower 4, the connection between the seventeenth pipe 217 and the inner cavity of the absorption tower 4, and the connection between the eighteenth pipe 218 and the shell side of the first shell and tube condenser 2 and the inner cavity of the storage tank 5, when the jet vacuum pump 8 is working, the air in the inner cavity of the distillation tower 1, the shell side of the first shell and tube condenser 2, the tube side of the second shell and tube condenser 3, the inner cavity of the storage tank 5 and the inner cavity of the absorption tower 4 is extracted, thereby realizing a vacuum environment.

[0024] In the present invention, “left” and “right” are relative positions used for the convenience of describing positional relationships, and therefore cannot be understood as absolute positions to limit the scope of protection.

[0025] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

[0026] The above description, in conjunction with the accompanying drawings, details the preferred embodiments and examples of the present invention. However, the present invention is not limited to the above embodiments and examples. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the concept of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-temperature distillation and purification device for a mixed acid containing hydrofluoric acid, characterized in that: It includes a distillation tank, a first shell and tube condenser, a second shell and tube condenser, an absorption tower, a storage tank, a two-stage heat pump, a dry vacuum pump, and a jet vacuum pump; A mixed acid circulation pipeline is provided between the distillation tank, the first shell and tube condenser, the second shell and tube condenser and the absorption tower; the storage tank is used to collect condensed water flowing out of the first shell and tube condenser; a condensation pipeline is provided between the first shell and tube condenser, the second shell and tube condenser and the two-stage heat pump; the two-stage heat pump can cool the circulating medium in the condensation pipeline; a heating pipeline is provided between the heating component of the distillation tank and the two-stage heat pump; the two-stage heat pump can heat the circulating medium in the heating pipeline; a vacuum interlayer cavity is provided on the outside of the inner cavity of the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower; the vacuum interlayer cavity is connected to the air inlet end of the dry vacuum pump through a vacuum pipeline; the air inlet end of the jet vacuum pump is connected to the inner cavity of the absorption tower; the inner cavity side walls of the distillation tank, the first shell and tube condenser, the storage tank and the absorption tower are lined with a fluorine layer.

2. A low-temperature distillation and purification device for a mixed acid containing hydrofluoric acid according to claim 1, characterized in that: The mixed acid circulation pipeline includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a fifth pipeline, and a first circulation pump. The first pipeline realizes a through connection between the upper outlet of the inner cavity of the distillation tank and the shell side inlet of the first shell and tube condenser. The second pipeline realizes a through connection between the shell side gas outlet of the first shell and tube condenser and the tube side inlet of the second shell and tube condenser. The feed ends of the third pipeline and the fourth pipeline are through-connected with the tube side outlet of the second shell and tube condenser in parallel. The discharge end of the third pipeline is through-connected with the upper part of the inner cavity of the absorption tower. The liquid outlet end of the fourth pipeline is through-connected with the bottom of the inner cavity of the absorption tower. The fifth pipeline realizes a through connection between the spray inlet of the absorption tower and the bottom of the inner cavity of the absorption tower. The first circulation pump is connected in series to the fifth pipeline.

3. A low-temperature distillation purification device for a mixed acid containing hydrofluoric acid according to claim 2, characterized in that: The condensation pipeline includes a sixth pipeline, a seventh pipeline, an eighth pipeline, and a second circulation pump. The sixth pipeline realizes a through connection between the liquid outlet end of the cooling side of the two-stage heat pump and the tube side inlet of the first shell and tube condenser. The seventh pipeline realizes a through connection between the tube side outlet of the first shell and tube condenser and the shell side inlet of the second shell and tube condenser. The eighth pipeline realizes a through connection between the shell side outlet of the second shell and tube condenser and the liquid inlet end of the cooling side of the two-stage heat pump. The second circulation pump is connected in series to the eighth pipeline.

4. A low-temperature distillation and purification device for a mixed acid containing hydrofluoric acid according to claim 3, characterized in that: The heating pipeline includes a ninth pipeline, a tenth pipeline, and a third circulation pump. The ninth pipeline realizes a through connection between the liquid outlet end of the heating side of the two-stage heat pump and the inlet end of the heating component. The tenth pipeline realizes a through connection between the liquid inlet end of the heating side of the two-stage heat pump and the outlet end of the heating component. The third circulation pump is connected in series to the ninth pipeline.

5. The low-temperature distillation purification device for a mixed acid containing hydrofluoric acid according to claim 4, wherein: The heating component is a spiral sleeve.

6. The low-temperature distillation purification device for a mixed acid containing hydrofluoric acid according to claim 5, wherein: The vacuum pipeline includes an eleventh pipeline, a twelfth pipeline, a thirteenth pipeline, a fourteenth pipeline, and a fifteenth pipeline; the air inlet end of the eleventh pipeline is connected to the vacuum interlayer cavity of the distillation tank, the air inlet end of the twelfth pipeline is connected to the vacuum interlayer cavity of the first shell and tube condenser, the air inlet end of the thirteenth pipeline is connected to the vacuum interlayer cavity of the storage tank, and the air outlet ends of the eleventh pipeline, the twelfth pipeline and the thirteenth pipeline are connected in parallel to the inlet end of the fourteenth pipeline. The inlet end is connected through-connected, the fifteenth pipeline realizes the through-connection between the vacuum interlayer cavity of the absorption tower and the air inlet of the dry vacuum pump, the outlet end of the fourteenth pipeline is connected through-connected with the fifteenth pipeline, the inlet end of a sixteenth pipeline is connected through-connected with the air outlet end of the dry vacuum pump, the inlet end of a seventeenth pipeline is connected through-connected with the bottom of the inner cavity of the absorption tower, and the outlet ends of the sixteenth pipeline and the seventeenth pipeline are connected through-connected with the inlet end of the jet vacuum pump in parallel.

7. The low-temperature distillation purification device for a mixed acid containing hydrofluoric acid according to claim 6, wherein: An eighteenth pipeline realizes the through-connection between the shell-side liquid outlet of the first shell and tube condenser and the inner cavity of the storage tank.

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