A method for recovering waste acid used for treating chlorination distillation residue

Abstract

The invention discloses a waste acid recovery method for treating chlorination distillation residual liquid, belongs to the technical field of recycling and treating chlorination distillation waste acid, and is used to solve the problems in the prior art that the recovery of hydrochloric acid from chlorination distillation waste acid has high equipment requirements, high energy consumption, and easy clogging of equipment, which cannot be widely used in industry. The method comprises collecting chlorination distillation waste acid; adding salt to the chlorination distillation waste acid; the chlorination distillation waste acid undergoes decomposition during the pressure and heat preservation process to obtain hydrochloric acid gas; heat-exchanging the hydrochloric acid gas, condensing part of the hydrochloric acid gas to obtain concentrated hydrochloric acid; and spraying and absorbing the remaining hydrochloric acid gas that has not condensed with dilute hydrochloric acid. The invention can be used to recover hydrochloric acid from chlorination distillation waste acid.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling and treating waste acid from chlorination distillation, and in particular relates to a waste acid recycling method for treating chlorination distillation residual liquid. Background Art

[0002] In the prior art, the recovery and concentration of hydrochloric acid in the waste acid of chlorination distillation usually adopts a pressure swing distillation process or a salt-added extraction distillation process.

[0003] Among them, the pressure swing distillation process is based on the pressure sensitivity of the azeotrope of hydrochloric acid aqueous solution. By increasing or decreasing the operating pressure, the azeotropic composition of the hydrochloric acid aqueous solution changes, thereby achieving the purpose of changing the concentration of hydrochloric acid. The pressure swing distillation process is simple, and the purpose of concentrating hydrochloric acid can be achieved by only changing the pressure without adding other substances. However, this process has high requirements on the pressure and temperature tolerance of the equipment and high energy consumption, and cannot achieve the best economic benefits in the actual production process.

[0004] The salt extraction distillation process is to add salt to the hydrochloric acid solution and use the salt effect to change the HCl and H 2 O vapor-liquid phase equilibrium, increasing the relative volatility of HCl in the aqueous solution, thereby breaking the azeotropic point and achieving the purpose of concentrating hydrochloric acid. However, this process is prone to clogging equipment and cannot be widely used in industry. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a waste acid recovery method for treating chlorination distillation residues, so as to solve the problems in the prior art that the recovery of hydrochloric acid from chlorination distillation waste acid has high equipment requirements, high energy consumption, and easy clogging of equipment, which cannot be widely used in industry.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions.

[0007] The present invention provides a method for recovering waste acid used for treating chlorination distillation residue, comprising the following steps:

[0008] Step 1: collecting waste acid from chlorination distillation;

[0009] Step 2: adding salt to the chlorination distillation waste acid;

[0010] Step 3: The waste acid from chlorination distillation undergoes decomposition during the pressure and temperature maintenance process to obtain hydrochloric acid gas;

[0011] Step 4: exchanging heat with the hydrochloric acid gas, and condensing part of the hydrochloric acid gas to obtain concentrated hydrochloric acid;

[0012] Step 5: The remaining uncondensed hydrochloric acid gas is sprayed and absorbed by dilute hydrochloric acid to complete the recovery of hydrochloric acid in the chlorination distillation waste acid.

[0013] Furthermore, the recovery device used in the recovery method includes an analysis tower, a heat exchanger, an absorption tower, a salter and a dilute hydrochloric acid storage tank. The analysis tower, the heat exchanger and the absorption tower are connected in sequence, the discharge port of the salter is connected to the analysis tower, and the liquid inlet and liquid outlet of the dilute hydrochloric acid storage tank are both connected to the absorption tower.

[0014] Further, the recovery method comprises the following steps:

[0015] Step 1: collecting chlorination distillation waste acid, and supplying the chlorination distillation waste acid into the analysis tower through a waste acid supplier;

[0016] Add dilute hydrochloric acid to the dilute hydrochloric acid storage tank below the absorption tower;

[0017] Step 2: adding salt to the chlorination distillation waste acid in the analytical tower through a salt adder;

[0018] Step 3: Turn on the vacuum pump, heat source and stirring motor, control the pressure in the decomposition tower to reach the operating pressure and maintain the pressure, and control the temperature in the decomposition tower to reach the operating temperature and maintain the temperature, and the chlorination distillation waste acid is decomposed during the pressure and temperature maintenance process to obtain hydrochloric acid gas;

[0019] Step 4: The hydrochloric acid gas passes through a heat exchanger, and part of the hydrochloric acid gas is condensed to obtain concentrated hydrochloric acid, which is retained in a concentrated hydrochloric acid storage tank;

[0020] Step 5: The dilute hydrochloric acid in the dilute hydrochloric acid storage tank is supplied to the absorption tower, and the remaining hydrochloric acid gas that has not condensed passes through the concentrated hydrochloric acid storage tank and enters the absorption tower, where it is sprayed and absorbed by the dilute hydrochloric acid and then enters the dilute hydrochloric acid storage tank, thereby completing the recovery of hydrochloric acid in the chlorination distillation waste acid.

[0021] Furthermore, in step 2, the salt is magnesium chloride or calcium chloride.

[0022] Furthermore, in step 2, the amount of salt added is 250-350 kg per ton of chlorination distillation waste acid.

[0023] Furthermore, in step 3, the operating pressure in the analytical tower is 0.7-0.9 atm, the pressure holding time is 3-4 hours, the operating temperature is 80-100° C., and the heat holding time is 3-4 hours.

[0024] Furthermore, in step 3, the rotation speed of the stirring motor is 100-800 rpm.

[0025] Furthermore, in step 4, the outlet temperature of the heat exchanger is 15-25°C.

[0026] Furthermore, in step 5, the flow rate of the dilute hydrochloric acid supplied to the absorption tower is 25 to 50 kg / h, and the supply time is 3 to 4 hours.

[0027] Furthermore, the mass concentration of hydrochloric acid in the recovered condensate is 30-35%, and the mass concentration of dilute hydrochloric acid in the recovered dilute hydrochloric acid storage tank is 20-25%.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects.

[0029] A) The waste acid recovery method for treating chlorination distillation residue provided by the present invention combines the pressure-swing distillation process with the salt-adding extraction distillation process, adds salt to the chlorination distillation waste acid, and combines the negative pressure environment to make the hydrochloric acid in the chlorination distillation waste acid parse out in the form of gas, and then passes through the heat exchanger and the absorption tower to obtain concentrated hydrochloric acid and dilute hydrochloric acid, so that the chlorination distillation waste acid is efficiently recovered and reused, and the concentration and impurity content of the recovered hydrochloric acid meet the index requirements of hydrochloric acid reuse, and has the advantages of low energy consumption, simple operation, low operating cost, etc., and has positive promotion significance and significant application value. For the pressure-swing distillation process, combined with the salt-adding extraction distillation process, the operating pressure requirement in the process becomes lower, and while reducing the process cost, the safety of the process will also be increased. For the salt-adding extraction distillation process, the reduced pressure distillation will also make the salt effect in the salt-adding extraction distillation more prominent, and the hydrochloric acid parsing effect is better, thereby greatly reducing the equipment requirements and the required energy consumption, achieving zero discharge of waste acid and reducing environmental pollution and industrial costs.

[0030] B) The waste acid recovery method for treating chlorination distillation residue provided by the present invention, on the one hand, adds salt to the hydrochloric acid-water system, and the salt effect will have a very significant impact on the vapor-liquid equilibrium of the hydrochloric acid-water system, thereby changing the HCl-H 2 The relative volatility between the O components destroys the original constant boiling composition, and because of the non-volatility of the salt, it can be reused in the recovery process after evaporation and crystallization, and no by-products will be generated to cause secondary pollution, thus solving the technical difficulties in recycling and treating the waste acid from chlorination distillation; on the other hand, the reduced pressure distillation is based on the difference in the azeotropic point of hydrochloric acid under different pressures, and the purpose of further desorption of HCl is achieved by changing the distillation pressure; on the other hand, the salt adder is only connected to the analysis tower. During the recovery process, the salt is only added to the analysis kettle and does not circulate in the recovery device, so there is no problem of clogging the pipeline.

[0031] C) The waste acid recovery method for treating chlorination distillation residual liquid provided by the present invention is provided with an absorption tower and a dilute hydrochloric acid storage tank constituting a circulation loop with the absorption tower after the heat exchanger, and dilute hydrochloric acid is used as the absorption liquid in the absorption tower. After the hydrochloric acid gas that has not condensed enters the absorption tower, it will be absorbed by the dilute hydrochloric acid sprayed in the absorption tower, and circulate to the dilute hydrochloric acid storage tank together with the absorption liquid (i.e., dilute hydrochloric acid), so that a hydrochloric acid solution with increasing concentration can be obtained, and the conversion efficiency of the hydrochloric acid gas that has not condensed can be effectively improved. In the absorption process of the hydrochloric acid gas that has not condensed, the amount of hydrochloric acid gas desorbed in the initial stage is relatively large, and the concentration of the dilute hydrochloric acid as the absorption liquid is low, and the mass transfer driving force of the absorption operation is large, so that the absorption rate is fast. As the absorption proceeds, the concentration of the dilute hydrochloric acid continues to increase, the desorption process slows down, and the absorption operation also slows down, and finally an absorption liquid with absorption balance is obtained.

[0032] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0034] Figure 1 A flow chart of a method for recovering waste acid from chlorinated distillation residue provided in Example 1 of the present invention;

[0035] Figure 2 This is a schematic structural diagram of a recovery device in a waste acid recovery method for treating chlorination distillation residue provided in Example 1 of the present invention.

[0036] Reference numerals:

[0037] 1-waste acid feeder; 2-stirring motor; 3-heat source; 4-analysis tower; 5-salter; 6-thermometer; 7-vacuum gauge; 8-heat exchanger; 9-concentrated hydrochloric acid storage tank; 10-diluted hydrochloric acid storage tank; 11-absorption tower; 12-transfer pump; 13-vacuum pump; 14-connecting section; 15-regulating section. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0039] Embodiment 1

[0040] This embodiment provides a method for recovering waste acid used to treat chlorinated distillation residues, see Figure 1 to Figure 2 , including the following steps:

[0041] Step 1: collecting chlorination distillation waste acid, and supplying 1 t of chlorination distillation waste acid into the analysis tower 4 through the waste acid supplier 1;

[0042] Add 50-100 kg of dilute hydrochloric acid with a mass concentration of 10-15% into the dilute hydrochloric acid storage tank 10 below the absorption tower 11;

[0043] Step 2: adding salt (e.g., magnesium chloride / calcium chloride) to the analytical tower 4 through the salt adder 5;

[0044] Step 3: Turn on the vacuum pump 13, the heat source 3 and the stirring motor 2, control the pressure in the decomposition tower 4 to reach the operating pressure and maintain the pressure, and control the temperature in the decomposition tower 4 to reach the operating temperature and maintain the temperature, and the chlorination distillation waste acid is decomposed during the pressure and temperature maintenance process to obtain hydrochloric acid gas;

[0045] Step 4: The hydrochloric acid gas passes through the heat exchanger 8, and part of the hydrochloric acid gas is condensed to obtain concentrated hydrochloric acid, which is retained in the concentrated hydrochloric acid storage tank 9;

[0046] Step 5: The dilute hydrochloric acid in the dilute hydrochloric acid storage tank 10 is supplied to the absorption tower 11, and the remaining hydrochloric acid gas that has not condensed passes through the concentrated hydrochloric acid storage tank 9 and enters the absorption tower 11, where it is sprayed and absorbed by the dilute hydrochloric acid and then enters the dilute hydrochloric acid storage tank 10, thereby completing the recovery of hydrochloric acid in the chlorination distillation waste acid.

[0047] It should be noted that, in the process of recovering the waste acid from chlorination distillation, the dilute hydrochloric acid under the absorption tower 11 continuously absorbs the remaining hydrochloric acid gas that has not condensed, and after the treatment is complete, the condensate and the absorption liquid in the dilute hydrochloric acid storage tank 10 are the hydrochloric acid solution for recycling the waste acid from chlorination distillation. Among them, the mass concentration of hydrochloric acid in the recovered condensate is 30-35%, and the mass concentration of the dilute hydrochloric acid in the recovered dilute hydrochloric acid storage tank 10 is 20-25%.

[0048] Compared with the prior art, the waste acid recovery method for treating chlorination distillation residue provided in this embodiment combines the pressure-swing distillation process with the salt-adding extraction distillation process, and by adding salt to the chlorination distillation waste acid, and combining the negative pressure environment, the hydrochloric acid in the chlorination distillation waste acid is parsed out in the form of gas, and then concentrated hydrochloric acid and dilute hydrochloric acid are obtained through the heat exchanger 8 and the absorption tower 11, so that the chlorination distillation waste acid is efficiently recovered and reused, and the concentration and impurity content of the recovered hydrochloric acid meet the index requirements of hydrochloric acid reuse, and has the advantages of low energy consumption, simple operation, and low operating cost, and has positive promotion significance and significant application value. For the pressure-swing distillation process, combined with the salt-adding extraction distillation process, the operating pressure requirement in the process becomes lower, and while reducing the process cost, the safety of the process will also be increased. For the salt-adding extraction distillation process, the reduced pressure distillation will also make the salt effect in the salt-adding extraction distillation more prominent, and the hydrochloric acid parsing effect is better, thereby greatly reducing the equipment requirements and the required energy consumption, achieving zero discharge of waste acid and reducing environmental pollution and industrial costs.

[0049] Specifically, on the one hand, adding salt to the hydrochloric acid-water system will have a significant impact on the vapor-liquid equilibrium of the hydrochloric acid-water system, thereby changing the HCl-H 2 O components, destroying the original constant boiling composition, and because of the non-volatility of the salt, it can be reused in the recovery process after evaporation and crystallization, and no by-products will be generated to cause secondary pollution, thus solving the technical problem of recycling and treating the waste acid from chlorination distillation; on the other hand, the reduced pressure distillation is based on the difference in the azeotropic point of hydrochloric acid under different pressures, and the purpose of further desorption of HCl is achieved by changing the distillation pressure; on the other hand, the salt adder 5 is only connected to the analysis tower 4. During the recovery process, the salt is only added to the analysis kettle, and does not circulate in the recovery device, so there is no problem of clogging the pipeline.

[0050] At the same time, by arranging an absorption tower 11 after the heat exchanger 8 and a dilute hydrochloric acid storage tank 10 forming a circulation loop with the absorption tower 11, using dilute hydrochloric acid as the absorption liquid in the absorption tower 11, the hydrochloric acid gas that has not condensed will be absorbed by the dilute hydrochloric acid sprayed in the absorption tower 11 after entering the absorption tower 11, and circulate to the dilute hydrochloric acid storage tank 10 together with the absorption liquid (i.e., dilute hydrochloric acid), so that a hydrochloric acid solution with increasing concentration can be obtained, effectively improving the conversion efficiency of the hydrochloric acid gas that has not condensed. In the absorption process of the hydrochloric acid gas that has not condensed, the amount of hydrochloric acid gas desorbed in the initial stage is relatively large, and the concentration of the dilute hydrochloric acid as the absorption liquid is low, the mass transfer driving force of the absorption operation is large, and the absorption rate is fast. As the absorption proceeds, the concentration of the dilute hydrochloric acid continues to increase, the desorption process slows down, and the absorption operation also slows down, and finally an absorption liquid with absorption equilibrium is obtained.

[0051] It is worth noting that the amount of salt added will affect the chlorination distillation waste acid in the analysis tower 4. Therefore, in the above step 2, the amount of salt added is 250-350 kg per ton of chlorination distillation waste acid. In this way, limiting the amount of salt added to the above range can ensure the analysis rate of chlorination distillation waste acid on the basis of effectively saving the amount of salt added, thereby further improving the recovery rate of hydrochloric acid in chlorination distillation waste acid.

[0052] Exemplarily, in order to further reduce the energy consumption of the above-mentioned waste acid recovery method for treating chlorinated distillation residues and promote the analysis of chlorinated distillation waste acid, in the above-mentioned step 3, the operating pressure in the analysis tower 4 is 0.7-0.9atm, the pressure holding time is 3-4h, the operating temperature is 80-100°C, and the insulation time is 3-4h. It should be noted that compared with pressure swing distillation, the requirements for the above-mentioned operating pressure, pressure holding time, operating temperature and insulation time are lower, which can not only further reduce the energy consumption of the above-mentioned waste acid recovery method for treating chlorinated distillation residues, effectively reduce the requirements for equipment, but also facilitate the treatment and recycling of chlorinated distillation waste acid, and improve the recovery effect of chlorinated distillation waste acid.

[0053] In order to promote the mixing of salt and chlorination distillation waste acid, the rotation speed of the stirring motor 2 in the above step 3 is 100-800 rpm.

[0054] In order to ensure the condensation effect, in the above step 4, the outlet temperature of the heat exchanger 8 is 15-25°C.

[0055] It is also worth noting that the absorption flow rate of the dilute hydrochloric acid and the supply time of the dilute hydrochloric acid will affect the absorption of the uncondensed hydrochloric acid gas in the absorption tower. Therefore, illustratively, in the above step 5, the flow rate of the dilute hydrochloric acid supplied to the absorption tower 11 is 25-50 kg / h, and the supply time is 3-4 hours. In this way, the flow rate and supply time of the dilute hydrochloric acid supplied to the absorption tower 11 are limited to the above ranges, which can effectively save the amount of dilute hydrochloric acid used and ensure the absorption rate of the uncondensed hydrochloric acid gas, thereby further improving the recovery rate of hydrochloric acid in the chlorination distillation waste acid.

[0056] For example, the above-mentioned waste acid recovery method for treating chlorination distillation residues adopts a recovery device with the following structure, see Figure 2 , including a waste acid feeder 1, a decomposition tower 4 (for example, a sealed decomposition tower), a heat exchanger 8 (for example, a tubular heat exchanger), a concentrated hydrochloric acid storage tank 9, an absorption tower 11, a salter 5 and a dilute hydrochloric acid storage tank 10, wherein the waste acid feeder 1, the decomposition tower 4, the heat exchanger 8, the concentrated hydrochloric acid storage tank 9 and the absorption tower 11 are connected in sequence, the discharge port of the salter 5 is connected to the decomposition tower 4, and the liquid inlet and the liquid outlet of the dilute hydrochloric acid storage tank 10 are both connected to the absorption tower 11.

[0057] It can be understood that in order to ensure the temperature and pressure in the analysis tower 4 and promote the analysis of hydrochloric acid in the chlorination distillation waste acid, the above-mentioned hydrochloric acid recovery device in the chlorination distillation waste acid also includes a heat source 3 for providing heat to the analysis tower 4 and a vacuum pump 13 for providing a negative pressure environment for the analysis tower 4.

[0058] In order to facilitate the control of the negative pressure state of the entire environment, for example, the vacuum pump 13 is connected to the dilute hydrochloric acid storage tank 10. It should be noted that the vacuum pump 13 is connected to the space above the dilute hydrochloric acid in the dilute hydrochloric acid storage tank 10 using a short tube, which basically does not affect the delivery of the dilute hydrochloric acid by the delivery pump 12.

[0059] In order to supply liquid from the dilute hydrochloric acid storage tank 10 to the absorption tower 11, a delivery pump 12 is provided on the connecting pipeline between the dilute hydrochloric acid storage tank 10 and the absorption tower 11. The delivery pump 12 provides power for the flow of the dilute hydrochloric acid so that the dilute hydrochloric acid can be smoothly supplied to the absorption tower 11.

[0060] In order to monitor the pressure and / or temperature in the analysis tower 4, the above-mentioned waste acid recovery method for treating chlorination distillation residue also includes a temperature monitor (for example, thermometer 6) for monitoring the temperature in the analysis tower 4 and / or a vacuum gauge 7 for monitoring the experimental environment pressure. Exemplarily, the temperature monitor is arranged at the top of the analysis tower 4, and the vacuum gauge 7 is arranged on the connecting pipeline between the analysis tower 4 and the heat exchanger 8.

[0061] In order to promote the mixing between salt and chlorination distillation waste acid, the above-mentioned waste acid recovery method for treating chlorination distillation residue also includes a stirring component arranged in the analysis tower 4 and a stirring motor 2 for driving the stirring component to rotate, and the output shaft of the stirring motor 2 is fixedly connected to the stirring component.

[0062] Considering that salt is solid, it will sink to the bottom of the analysis tower 4 after being added to the analysis tower 4. Therefore, the stirring component is arranged at the bottom of the analysis tower 4, and the rotating shaft of the stirring component coincides with the axis of the analysis tower 4, which can be beneficial to the uniformity of stirring.

[0063] As for the structure of the stirring assembly, specifically, the stirring shaft and the stirring impeller fixedly connected to the stirring shaft, the stirring impeller includes a plurality of stirring blades arranged along the circumference of the stirring shaft.

[0064] In order to improve the stirring efficiency of the stirring assembly, the stirring motor 2 is a reciprocating motor, and the stirring blade includes a connecting section 14 and an adjusting section 15 in a direction gradually away from the stirring shaft, one end of the connecting section 14 is fixedly connected to the connecting shaft, and the other end of the connecting shaft is elastically rotatably connected to the adjusting section 15. In this way, on the one hand, the reciprocating motor drives the connecting section 14 and the adjusting section 15 to simultaneously have circumferential rotation and axial linear motion, so that the space in the analytical tower 4 can be fully stirred within a certain height range. On the other hand, since the adjusting section 15 is elastically rotatably connected to the connecting section, when the reciprocating motor drives the adjusting section 15 and the connecting section 14 to move downward and switches to upward movement, at the lowest point, due to the effect of inertia, the adjusting section 15 will move in the opposite direction to the connecting section 14, that is, the adjusting section 15 will continue to move downward for a distance to stir the salt and chlorinated distillation waste acid at the bottom of the analysis tower 4 to promote the mixing of the two; when the reciprocating motor drives the adjusting section 15 and the connecting section 14 to move upward and switches to downward movement, at the highest point, due to the effect of inertia, the adjusting section 15 will continue to move upward for a distance, thereby being able to drive the hydrochloric acid gas obtained by analysis to accelerate the separation from the chlorinated distillation waste acid and increase the escape speed of the hydrochloric acid gas.

[0065] In order to further accelerate the separation of hydrochloric acid gas from chlorinated distillation waste acid, gas producing holes are provided on the above-mentioned connecting section 14 and the adjusting section 15. Through the setting of the gas producing holes, the disturbance of the chlorinated distillation waste acid can be effectively increased during the rotation of the stirring blades, thereby further accelerating the separation of hydrochloric acid gas from the chlorinated distillation waste acid.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for recovering waste acid from chlorinated distillation residues, characterized in that: The steps include: Step 1: collecting waste acid from chlorination distillation; Step 2: adding salt to the chlorination distillation waste acid; Step 3: The waste acid from chlorination distillation undergoes decomposition during the pressure and temperature maintenance process to obtain hydrochloric acid gas; Step 4: exchanging heat with the hydrochloric acid gas, and condensing part of the hydrochloric acid gas to obtain concentrated hydrochloric acid; Step 5: The remaining hydrochloric acid gas that has not condensed is sprayed and absorbed by dilute hydrochloric acid to complete the recovery of hydrochloric acid in the chlorination distillation waste acid; The recovery device used in the recovery method includes an analysis tower, a heat exchanger, an absorption tower, a salter and a dilute hydrochloric acid storage tank, wherein the analysis tower, the heat exchanger and the absorption tower are connected in sequence, the discharge port of the salter is connected to the analysis tower, and the liquid inlet and the liquid outlet of the dilute hydrochloric acid storage tank are both connected to the absorption tower; The recycling device also includes a stirring component arranged in the analytical tower and a stirring motor for driving the stirring component to rotate, wherein the stirring component is arranged at the bottom of the analytical tower; The stirring assembly comprises a stirring shaft and a stirring impeller fixedly connected to the stirring shaft, and the stirring impeller comprises a plurality of stirring blades arranged along the circumference of the stirring shaft; the stirring motor is a reciprocating motor, and the stirring blade comprises a connecting section and an adjusting section which are sequentially connected in a direction gradually away from the stirring shaft, one end of the connecting section is fixedly connected to the connecting shaft, and the other end of the connecting shaft is elastically rotatably connected to the adjusting section, and the reciprocating motor drives the connecting section and the adjusting section to have circumferential rotation and axial linear motion at the same time; in the process of switching from the downward movement of the adjusting section and the connecting section driven by the reciprocating motor to the upward movement, at the lowest point, due to the effect of inertia, the movement direction of the adjusting section is opposite to that of the connecting section, and the adjusting section continues to move downward to stir the salt and chlorination distillation waste acid at the bottom of the analytical tower; in the process of switching from the upward movement of the adjusting section and the connecting section driven by the reciprocating motor to the downward movement, at the highest point, due to the effect of inertia, the adjusting section continues to move upward; The connecting section and the regulating section are both provided with gas-generating holes.

2. The method for recovering waste acid from chlorinated distillation residue according to claim 1, characterized in that: Step 1: collecting the waste acid from chlorination distillation and supplying the waste acid from chlorination distillation to a decomposition tower; Add dilute hydrochloric acid to the dilute hydrochloric acid storage tank below the absorption tower; Step 2: adding salt to the chlorination distillation waste acid in the analytical tower through a salt adder; Step 3: Turn on the vacuum pump, the heat source and the stirring motor, control the pressure in the decomposition tower to reach the operating pressure and maintain the pressure, and control the temperature in the decomposition tower to reach the operating temperature and maintain the temperature, and the chlorination distillation waste acid is decomposed during the pressure and temperature maintenance process to obtain hydrochloric acid gas; Step 4: The hydrochloric acid gas passes through a heat exchanger, and part of the hydrochloric acid gas is condensed to obtain concentrated hydrochloric acid; Step 5: The dilute hydrochloric acid in the dilute hydrochloric acid storage tank is supplied to the absorption tower, and the remaining hydrochloric acid gas that has not condensed passes through the concentrated hydrochloric acid storage tank and enters the absorption tower, where it is sprayed and absorbed by the dilute hydrochloric acid and then enters the dilute hydrochloric acid storage tank, thereby completing the recovery of hydrochloric acid in the chlorination distillation waste acid.

3. The method for recovering waste acid from chlorinated distillation residue according to claim 2, characterized in that: In step 2, the salt is magnesium chloride or calcium chloride.

4. The method for recovering waste acid from chlorinated distillation residue according to claim 2, wherein: In the step 2, the amount of salt added is 250-350 kg per ton of chlorination distillation waste acid.

5. The method for recovering waste acid from chlorinated distillation residue according to claim 2, characterized in that: In the step 3, the operating pressure in the analytical tower is 0.7-0.9 atm, the pressure holding time is 3-4 hours, the operating temperature is 80-100° C., and the temperature holding time is 3-4 hours.

6. The method for recovering waste acid from chlorinated distillation residue according to claim 2, characterized in that: In step 3, the rotation speed of the stirring motor is 100-800 rpm.

7. The method for recovering waste acid from chlorinated distillation residue according to claim 2, characterized in that: In step 4, the outlet temperature of the heat exchanger is 15-25°C.

8. The method for recovering waste acid from chlorinated distillation residue according to claim 2, characterized in that: In step 5, the flow rate of the dilute hydrochloric acid supplied to the absorption tower is 25 to 50 kg / h, and the supply time is 3 to 4 hours.

9. The method for recovering waste acid from chlorinated distillation residue according to claim 2, characterized in that: The mass concentration of hydrochloric acid in the recovered condensate is 30-35%, and the mass concentration of dilute hydrochloric acid in the recovered dilute hydrochloric acid storage tank is 20-25%.

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