Hydrofluoric acid recovery device for substituted aromatic hydrogen fluoride diazonium salt pyrolytic reaction waste liquid

Abstract

The utility model provides a hydrofluoric acid recovery device for replacing aromatic hydrogen fluoride diazonium salt pyrolytic reaction waste liquid. The hydrofluoric acid recovery device comprises a rectifying still, a rectifying tower, a reflux device, an oil-water separator, a moisture meter, a liquid level meter and a finished product receiving tank, the top of the rectifying tower is connected with an inlet end of a reflux device, an outlet end of the reflux device is connected with an oil-water separator, an upper-layer overflow port of the oil-water separator is connected with the rectifying still, and a lower-layer outlet end of the oil-water separator is connected with a finished product receiving tank; the side wall of the oil-water separator is provided with a transparent observation window; the transparent observation window is connected with a liquid level meter; and the moisture meter and the liquid level meter are both connected with the oil-water separator. Probes of the moisture meter and the liquid level meter are positioned in the oil-water separator, so that monitoring is facilitated. After hydrofluoric acid is recovered by the device, an upper-layer organic solvent flows back to the rectifying still again, so that residual liquid is reduced, and meanwhile, sodium hydrogenfluoride and sodium fluoride can be further recovered conveniently; concentrated sulfuric acid is not used, hazardous waste is not generated, and the process temperature is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of treatment of waste liquid from pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salts, in particular to a hydrofluoric acid recovery device for waste liquid from pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salts. Background Art

[0002] The reaction process of preparing fluorinated aromatic hydrocarbons from the diazonium hydrogen fluoride salt of substituted benzene is as follows:

[0003]

[0004] In the formula, the position of the substituent R is not limited, the number of the substituent R is not limited to one, and the substituent R is H, alkyl or halogen.

[0005] After the pyrolysis reaction is completed, the inorganic layer contains excess hydrogen fluoride and the like.

[0006] Existing fluorinated aromatics manufacturers at home and abroad can only partially recover hydrogen fluoride, and the rest is treated as waste. The existing treatment method is mainly to add concentrated sulfuric acid to the above inorganic layer to recover hydrogen fluoride:

[0007] 2NaHF2+H2SO4(concentrated)→Na2SO4+4HF

[0008] However, after recovering hydrogen fluoride, the residual liquid is discarded, and there is too much residual liquid. At the same time, since the hydrogen fluoride is completely evaporated by concentrated sulfuric acid, not only the process temperature is too high, but also a large amount of waste acid is generated, forming hazardous waste. In order to recover as much hydrogen fluoride as possible, not to generate hazardous waste, and to reduce the process temperature, the present invention provides a hydrofluoric acid recovery device for replacing the waste liquid of the pyrolysis reaction of aromatic hydrogen fluoride diazonium salt. Utility Model Content

[0009] In order to solve the deficiencies existing in the related art, the utility model provides a hydrofluoric acid recovery device for replacing the waste liquid of the pyrolysis reaction of aromatic hydrogen fluoride diazonium salt. The upper overflow port of the oil-water separator of the device is connected to the distillation kettle, the lower layer of hydrofluoric acid is recovered, and the upper layer of organic solvent is refluxed to the distillation kettle, thereby reducing the residual liquid and facilitating the subsequent further recovery of sodium hydrogen fluoride and sodium fluoride; concentrated sulfuric acid is not used, no hazardous waste is generated, and the process temperature is reduced.

[0010] The technical solution of the utility model to solve the above technical problems is as follows:

[0011] A hydrofluoric acid recovery device for replacing waste liquid from the pyrolysis reaction of aromatic hydrogen fluoride diazonium salt, comprising a rectification kettle, a rectification tower, a reflux device, an oil-water separator, a moisture meter, a liquid level meter, and a finished product receiving tank;

[0012] The upper part of the distillation kettle is connected to the distillation tower, the top of the distillation tower is connected to the inlet end of the reflux device, the outlet end of the reflux device is connected to the oil-water separator, the upper overflow port of the oil-water separator is connected to the distillation kettle, and the lower outlet end is connected to the finished product receiving tank;

[0013] The side wall of the oil-water separator is provided with a transparent observation window, and the transparent observation window is connected to a liquid level meter;

[0014] The moisture meter and the liquid level meter are both connected to the oil-water separator. The probes of the moisture meter and the liquid level meter are located inside the oil-water separator for easy monitoring.

[0015] On the basis of the above technical solution, the present invention can also be improved as follows.

[0016] Furthermore, the hydrofluoric acid recovery device for the waste liquid of the pyrolysis reaction of the substituted aromatic hydrogen fluoride diazonium salt further includes a front and rear distillation receiving tank, the top of which is connected to the bottom of the oil-water separator, and the bottom of which is connected to the distillation kettle. The front distillation is received before the finished product, and the rear distillation is received after the finished product. The front and rear distillation receiving tank is a receiving tank shared by the front distillation and the rear distillation.

[0017] Furthermore, in the above-mentioned hydrofluoric acid recovery device for the pyrolysis reaction waste liquid of the substituted aromatic hydrogen fluoride diazonium salt, the reflux device includes a top condenser and an external condenser assembly, the bottom of the top condenser is connected to the top of the distillation tower, and the top of the top condenser is connected to the external condenser assembly through a pipeline.

[0018] Furthermore, in the above-mentioned hydrofluoric acid recovery device for the pyrolysis reaction waste liquid of substituted aromatic hydrogen fluoride diazonium salt, the external condenser assembly includes a first external condenser and a second external condenser connected in series up and down, and the top of the tower top condenser is connected to the top of the first external condenser through a pipeline.

[0019] Furthermore, in the above-mentioned hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of the substituted aromatic hydrogen fluoride diazonium salt, the gas phase pipe outlet of the tower top condenser is connected to a temperature display.

[0020] Furthermore, in the above-mentioned hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of the substituted aromatic hydrogen fluoride diazonium salt, a regulating valve is connected to the pipeline connecting the second external condenser and the tower top condenser.

[0021] Furthermore, in the above-mentioned hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of the substituted aromatic hydrogen fluoride diazonium salt, a shut-off valve is connected to the pipeline connecting the lower outlet end of the oil-water separator and the finished product receiving tank.

[0022] Furthermore, the hydrofluoric acid recovery device for the pyrolysis reaction waste liquid of the substituted aromatic hydrogen fluoride diazonium salt further includes a PLC controller, the output end of the moisture meter is connected to the input end of the PLC controller, and the output end of the PLC controller is connected to the input end of the cut-off valve. The moisture meter and the cut-off valve are linked to prevent the organic solvent from laminarly flowing to the finished product receiving kettle.

[0023] Furthermore, in the above-mentioned hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt, the moisture meter is an ORP meter.

[0024] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0025] (1) This device uses azeotropic distillation through a distillation kettle, a distillation tower, and a reflux device to separate and purify hydrofluoric acid from fluorine-containing waste liquid. Compared with traditional dry evaporation and concentrated sulfuric acid distillation methods, it reduces the process operating temperature, achieves energy saving and carbon reduction effects, and improves process safety.

[0026] (2) An internal reflux device and an external reflux device are used to control the internal reflux and external reflux flow rates respectively through refrigerants of different temperatures, thereby improving the quality of recovered hydrofluoric acid and meeting the quality requirements for external sales.

[0027] (3) An oil-water separator is creatively used to separate the organic solvent and hydrofluoric acid condensed by the condenser. The upper organic solvent is returned to the distillation kettle through the overflow port to continue to serve as an azeotropic solvent, reducing the amount of solvent used and avoiding the caking of materials in the kettle. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic structural diagram of a hydrofluoric acid recovery device for waste liquid from pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salts provided in an embodiment of the utility model.

[0029] In the figure, 1, distillation kettle; 2, distillation tower; 3, oil-water separator; 4, tower top condenser; 5, first external condenser; 6, second external condenser; 7, liquid level meter; 8, front and rear distillation receiving tanks; 9, finished product receiving tank; 10, regulating valve; 11, shut-off valve; 12, moisture meter. DETAILED DESCRIPTION

[0030] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0032] A hydrofluoric acid recovery device for replacing waste liquid from the pyrolysis reaction of aromatic hydrogen fluoride diazonium salts, comprising a rectification kettle 1, a rectification tower 2, a reflux device, an oil-water separator 3, a moisture meter 12, a liquid level meter 7, and a finished product receiving tank 9;

[0033] The upper part of the distillation kettle 1 is connected to the distillation tower 2, the top of the distillation tower 2 is connected to the inlet end of the reflux device, the outlet end of the reflux device is connected to the oil-water separator 3, the upper overflow port of the oil-water separator 3 is connected to the distillation kettle 1, and the lower outlet end is connected to the finished product receiving tank 9;

[0034] The side wall of the oil-water separator 3 is provided with a transparent observation window, and the transparent observation window is connected to a liquid level gauge 7;

[0035] The moisture meter and the liquid level meter 7 are both connected to the oil-water separator 3 .

[0036] On the basis of the above technical solution, the present invention can also be improved as follows.

[0037] It also includes a front and rear distillation receiving tank 8, the top of the front and rear distillation receiving tank 8 is connected to the bottom of the oil-water separator 3, and the bottom of the front and rear distillation receiving tank 8 is connected to the distillation kettle 1.

[0038] The reflux device comprises a tower top condenser 4 and an external condenser assembly. The bottom of the tower top condenser 4 is connected to the top of the distillation tower 2, and the top of the tower top condenser 4 is connected to the external condenser assembly through a pipeline.

[0039] The external condenser assembly comprises a first external condenser 5 and a second external condenser connected in series up and down, and the top of the tower top condenser 4 is connected to the top of the first external condenser 5 through a pipeline.

[0040] The gas phase pipe outlet of the tower top condenser 4 is connected with a temperature display.

[0041] The pipeline connecting the second external condenser and the tower top condenser 4 is connected with a regulating valve 10 .

[0042] A cut-off valve 11 is connected to the pipeline connecting the lower outlet end of the oil-water separator 3 and the finished product receiving tank 9 .

[0043] It also includes a PLC controller. The output end of the moisture meter 12 is connected to the input end of the PLC controller, and the output end of the PLC controller is connected to the input end of the cut-off valve 11.

[0044] The moisture meter is an orp meter.

[0045] Working principle of the hydrofluoric acid recovery device for the waste liquid of the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt:

[0046] (1) Main components of fluorine-containing waste liquid: HF (65%), NaHF (19%), H2O (14%), organic impurities (2%);

[0047] (2) Fluorine-containing waste liquid and organic solvents, such as toluene and xylene, are added to the distillation kettle 1. Toluene is used as an example in the following description. Through azeotropic distillation, toluene, hydrogen fluoride and water form a ternary azeotrope and enter the distillation tower 2 and are condensed through a reflux device. Then, toluene and hydrofluoric acid are separated into layers in the oil-water separator 3. The upper layer of toluene overflows from the upper overflow port to the distillation kettle 1 for recycling, and the lower layer of hydrofluoric acid flows through the lower outlet to the finished product receiving tank 9.

[0048] (3) A is a reflux device, including a tower top condenser 4 and an external condenser, the external condenser including a first external condenser 5 and a second external condenser, an internal reflux is performed through the tower top condenser 4 (equipped with cooling water and frozen brine, and the cooling temperature is different by different ratios of the two, thereby controlling the flow rate of the internal reflux), and an external reflux is performed through the external condenser to condense vaporized toluene, hydrogen fluoride, and water, and control the color of the evaporated hydrofluoric acid. The first external condenser is cooled by water, and the second external condenser is cooled by frozen brine, which is beneficial to energy saving.

[0049] (4) B is an oil-water separator 3, which is equipped with a moisture meter to determine the stratification interface, and observes the liquid level and stratification interface through a liquid level gauge 7 at a transparent observation window, and separates the evaporated toluene and hydrofluoric acid therein, thereby recovering the hydrofluoric acid. The upper toluene overflows to the distillation kettle 1 through the upper overflow port of the oil-water separator 3, and continues to be used as the solvent for azeotropic dehydration, and at the same time is used as the solvent for pulping in the kettle after the distillation is completed.

[0050] Working process:

[0051] Add fluorine-containing waste liquid and toluene to the distillation kettle 1, start stirring, open the steam valve of the distillation kettle 1 (not shown in the figure, a steam tank is connected in front of the distillation kettle, and the steam valve is connected to the pipeline between the distillation kettle and the steam tank) and heat until the material is distilled out. First adjust the distillation tower 2 to a full reflux state, maintain for 1 hour, and when the distillate is nearly colorless, open the receiving valve of the finished product receiving tank 9, adjust the reflux ratio to 2:1, control the final temperature of the tower kettle at 100°C, and the final temperature of the tower top at 90°C, and evaporate the three-component azeotrope of toluene, water and hydrogen fluoride. Toluene and hydrofluoric acid are separated in the oil-water separator 3, and the upper layer of toluene overflows to the distillation kettle 1 for recycling, and the lower layer of hydrofluoric acid is sent to the finished product receiving tank 9.

[0052] Technical results achieved:

[0053] (1) The azeotropic distillation device is used to separate and purify hydrofluoric acid from fluorine-containing waste liquid. Compared with the traditional dry evaporation method and sulfuric acid distillation method, the process operating temperature is reduced, energy saving and carbon reduction are achieved, and process safety is improved.

[0054] (2) An internal reflux device and an external reflux device are used to control the internal reflux and external reflux flow rates respectively through refrigerants of different temperatures, thereby improving the quality of recovered hydrofluoric acid and meeting the quality requirements for external sales.

[0055] (3) The oil-water separator 3 is creatively used to separate the organic solvent and hydrofluoric acid condensed by the reflux device. The organic solvent returns to the distillation kettle 1 through the upper overflow port and continues to serve as an azeotropic solvent, thereby reducing the amount of solvent used and avoiding the caking of the material in the kettle.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hydrofluoric acid recovery device for waste liquid from pyrolysis of substituted aromatic hydrogen fluoride diazonium salts, characterized in that: Including distillation kettle, distillation tower, reflux device, oil-water separator, moisture meter, liquid level meter, finished product receiving tank; The upper part of the distillation kettle is connected to the distillation tower, the top of the distillation tower is connected to the inlet end of the reflux device, the outlet end of the reflux device is connected to the oil-water separator, the upper overflow port of the oil-water separator is connected to the distillation kettle, and the lower outlet end is connected to the finished product receiving tank; The side wall of the oil-water separator is provided with a transparent observation window, and the transparent observation window is connected to a liquid level meter; The moisture meter and the liquid level meter are both connected to the oil-water separator.

2. The hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 1, characterized in that: It also includes front and rear distillation receiving tanks, the tops of which are connected to the bottom of the oil-water separator, and the bottoms of which are connected to the distillation kettle.

3. The hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 1, characterized in that: The reflux device comprises a tower top condenser and an external condenser assembly. The bottom of the tower top condenser is connected to the top of the distillation tower, and the top of the tower top condenser is connected to the external condenser assembly through a pipeline.

4. The hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 3, characterized in that: The external condenser assembly comprises a first external condenser and a second external condenser which are connected in series up and down, and the top of the tower top condenser is connected to the top of the first external condenser through a pipeline.

5. The hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 3, characterized in that: The gas phase pipe outlet of the tower top condenser is connected with a temperature display.

6. The hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 4, characterized in that: The pipeline connecting the second external condenser and the tower top condenser is connected with a regulating valve.

7. The hydrofluoric acid recovery device for the waste liquid from the pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 1, characterized in that: A cut-off valve is connected to the pipeline connecting the lower outlet end of the oil-water separator and the finished product receiving tank.

8. The hydrofluoric acid recovery device for waste liquid from pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 1, characterized in that: It also includes a PLC controller, the output end of the moisture meter is connected to the input end of the PLC controller, and the output end of the PLC controller is connected to the input end of the cut-off valve.

9. The hydrofluoric acid recovery device for waste liquid from pyrolysis reaction of substituted aromatic hydrogen fluoride diazonium salt according to claim 1, characterized in that: The moisture meter is an orp meter.

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