A device and method for separating waste acid from mixed dinitrobenzene production

Abstract

The invention discloses a waste acid separation device for mixed dinitrobenzene production, comprising: a purification tower, a packing is arranged inside the purification tower, an acid inlet pipe for injecting waste acid liquid and a benzene inlet pipe for injecting benzene liquid are arranged at the top and bottom of the packing respectively, and a benzene storage tank, wherein the benzene storage tank is located at the top of the purification tower and continuously supplies benzene liquid to the purification tower by using a high head difference. A purification tower with a packing is added, benzene is a continuous phase and waste acid is a dispersed phase entering the purification tower, and the waste acid liquid is dispersed at the top of the tower and flows downward by using the density difference between the waste acid liquid and the benzene liquid, while the benzene liquid continuously enters the bottom of the purification tower with the help of the high head difference and flows upward, and the two form a countercurrent extraction to remove the nitrate in the waste acid. Thereby, the nitrate content in the waste acid is reduced from 0.6% to 0.8% before separation to less than 0.1% after separation, so as to avoid the pollution of the alkaline water inside the tail gas absorption tower caused by the nitrate flowing into the tail gas absorption tower, and reduce the difficulty of subsequent treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of waste liquid recovery and treatment, and in particular relates to a device for separating waste acid from mixed dinitrobenzene production, and a separation method for the device for separating waste acid from mixed dinitrobenzene production. Background Art

[0002] Mixed dinitrobenzene is mainly used for hydrogenation to produce phenylenediamine, and is also an inhibitor for molecular polymerization reactions. It can be used to produce pesticides and medicines. The current production process of mixed dinitrobenzene mainly includes several main processes: one-stage nitration, two-stage nitration, neutralization, and water washing. The process waste acid produced by the two-stage nitration is used for the first stage. The waste acid (called waste acid) with a mass concentration of 70% to 75% after the first stage nitration still contains nitrates with a mass concentration of 0.6% to 0.8%. At present, the recovery and treatment of nitrates in waste acid often adopts traditional kettle extraction. Benzene and waste acid are continuously transported to the extraction kettle in proportion through a benzene shielded pump and a waste acid delivery pump, and the stirrer on the extraction kettle is started to stir and mix. The extracted nitrate and benzene mixture flows into the acid benzene separator through the overflow pipe on the upper part of the kettle to the acid benzene tank for recycling. The 72 acid after extraction is then concentrated.

[0003] However, when using this method to concentrate waste acid, only part of the nitrate is eliminated, while most of the nitrate and nitrogen oxides are brought into the alkaline water of the tail gas absorption tower, causing the nitrate concentration in the alkaline water to exceed the standard, creating a pollution source. Summary of the invention

[0004] The present invention aims to solve the problem that the waste acid concentration treatment using a mixed stirring treatment method in the prior art will leave most of the nitrates and affect the alkaline water pollution in the tail gas absorption tower, and proposes the following technical solution:

[0005] A device for separating waste acid from mixed dinitrobenzene production, comprising:

[0006] A purification tower, wherein a packing is arranged inside the purification tower, and an acid inlet pipe for injecting waste acid liquid and a benzene inlet pipe for injecting benzene liquid are respectively arranged at the top and bottom of the packing, and the waste acid liquid is dispersed and flows downward after entering due to different densities, and the benzene liquid flows from bottom to top after entering, and the two form a countercurrent extraction in the packing to remove nitrates in the waste acid;

[0007] A benzene storage tank is provided at the top of the purification tower to continuously supply benzene liquid to the purification tower by utilizing the high head difference. A liquid level maintaining module is arranged inside the benzene storage tank. An external supply device injects benzene liquid from a liquid inlet on one side of the benzene storage tank. After a part of the benzene liquid is diverted by the liquid level maintaining component to keep the liquid level at the same height, the liquid enters the benzene inlet pipe through a pipeline from the liquid outlet at the bottom of the benzene storage tank.

[0008] As a preferred embodiment of the above technical solution, the liquid level maintaining module includes a retaining cylinder and a reflux assembly, a partition is provided in the middle of the retaining cylinder, a reflux pipe is provided on one side of the partition, one end of the reflux pipe passes through the retaining cylinder and extends to the outside of the retaining cylinder, the partition divides the retaining cylinder into a diversion bin and a reflux bin, the liquid level inside the benzene storage tank is flush with the top of the diversion bin, the reflux assembly pushes the benzene liquid inside the diversion bin to raise the liquid level in the reflux bin, and the benzene liquid is discharged from the retaining cylinder along the reflux pipe to replenish the liquid level.

[0009] As a preferred embodiment of the above technical solution, the reflux assembly includes a movable frame and a piston plate, the movable frame is connected to a driving member, the driving member drives the movable frame to move in a non-periodic manner, a plurality of return springs are arranged at the bottom of the piston plate, a plurality of through holes are opened in the middle of the piston plate, and a plurality of closing plates corresponding to the through holes are arranged at the bottom of the movable frame.

[0010] As a preferred embodiment of the above technical solution, the reflux assembly also includes a discharge member, which includes a discharge pipe and a mounting plate fixedly connected to the partition, the discharge pipe is located on the inner surface of the retaining cylinder and is provided with a discharge port, one end of the discharge pipe passes through the retaining cylinder and the benzene storage tank and extends to the outside, and the end of the discharge pipe is connected to the storage box of an external supply device through a pipeline, a screw rod is rotatably inserted in the middle of the discharge pipe, a slider is threadedly sleeved on one end of the screw rod, a piston block is provided at one end of the slider, and the piston block reciprocates inside the discharge pipe to control the opening and closing of the discharge port.

[0011] As a preferred embodiment of the above technical solution, a follower plate is movably inserted inside the mounting plate, a connecting spring is fixedly connected between the follower plate and the mounting plate, a gear is meshedly connected in the middle of the follower plate, and the gear is fixedly connected to the screw rod.

[0012] As a preferred embodiment of the above technical solution, it also includes: an acid-benzene separator, wherein the output end of the acid-benzene separator is connected to a drain pipe at the top of the purification tower through a pipeline, and the acid-benzene separator is used to separate acid and benzene from the mixed liquid.

[0013] As a preferred embodiment of the above technical solution, it also includes: a waste acid separator, wherein the input end of the waste acid separator is respectively connected to the second drainage pipe at the bottom of the purification tower and the input end of the acid-benzene separator, and the waste acid separator is used to separate the acid and organic phase from the mixed liquid output from the purification tower or the mixed liquid output from the acid-benzene separator.

[0014] As a preferred embodiment of the above technical solution, it also includes: a waste acid redistributor and a waste acid transfer tank connected to the waste acid redistributor, the waste acid redistributor and the waste acid transfer tank are both connected to the output end of the acid-benzene separator and the output end of the waste acid separator through pipelines, and the mixed liquid output from the output end of the acid-benzene separator and the mixed liquid output from the output end of the waste acid separator can be directly input into the waste acid redistributor, or transferred through the waste acid transfer tank and then input into the waste acid redistributor.

[0015] A separation method for a waste acid separation device for mixed dinitrobenzene production comprises the following steps:

[0016] S1, supply benzene liquid;

[0017] The benzene liquid in the benzene storage tank is continuously injected into the purification tower from the bottom of the purification tower by using a high head difference, and the liquid level maintaining module in the benzene storage tank keeps the internal liquid level at the same height for continuous constant flow supply;

[0018] S2, injecting waste acid;

[0019] The waste acid liquid is injected into the purification tower from the top of the purification tower, and the waste acid liquid is dispersed around the top of the purification tower;

[0020] S3, countercurrent extraction;

[0021] Utilizing the density difference between the waste acid liquid and the benzene liquid, the benzene liquid flowing upward and the waste acid liquid flowing downward form a countercurrent extraction to remove nitrates, the mixed liquid flowing upward flows out from the top of the purification tower and enters the S4 step, and the mixed liquid flowing downward flows out from the bottom of the purification tower and enters the S5 step;

[0022] S4, acid benzene separation;

[0023] The mixed liquid flowing out from the top of the purification tower enters the acid-benzene separator, and after the benzene in the mixed liquid is separated, it enters step S5;

[0024] S5, organic phase separation;

[0025] The mixed liquid flowing out from the bottom of the purification tower or the mixed liquid output from the acid-benzene separator is sent to the waste acid separator, so as to separate the organic phase in the mixed liquid to obtain acid liquid.

[0026] As a preferred embodiment of the above technical solution, it also includes: S6, acid solution concentration;

[0027] The acid liquid flowing out of the waste acid separator enters the waste acid re-separator and is further purified or concentrated for effective recovery and reuse.

[0028] The beneficial effects of the present invention are:

[0029] 1. Add a purification tower with fillers, with benzene as the continuous phase and waste acid as the dispersed phase entering the purification tower. Using the density difference between the waste acid liquid and the benzene liquid, the waste acid liquid is dispersed at the top of the tower and flows downward, while the benzene liquid continuously enters the bottom of the purification tower and flows upward with the help of the high position difference, and the two form a "countercurrent extraction" to remove the nitrate in the waste acid. Thereby, the nitrate content in the waste acid is reduced from 0.6% to 0.8% before separation to less than 0.1% after separation, and a large amount of nitrate can be recovered, avoiding the pollution of the alkaline water inside the tail gas absorption tower caused by the nitrate flow into the tail gas absorption tower, and reducing the difficulty of subsequent treatment;

[0030] 2. The external supply device supplies more benzene liquid than the outflow, thus performing "saturated supply", and the excess benzene liquid will flow from the diversion bin into the holding cylinder, which can ensure that the liquid level of the benzene storage tank is consistent, thereby making the benzene liquid flow rate entering the purification tower consistent;

[0031] 3. By moving the piston plate non-periodically, the liquid level inside the reflux bin is raised by using the communicating vessel principle, so that part of the liquid is discharged from the holding cylinder along the reflux pipe, thereby preventing the benzene liquid from being retained in the holding cylinder for too long and effectively replenishing the liquid level inside the benzene storage tank, further ensuring the supply effect of the benzene liquid;

[0032] 4. The set discharge member uses the movement of the piston plate as the power to push the piston block away from the discharge port position, and the benzene liquid inside the retaining cylinder can enter the discharge pipe through the discharge port position and be discharged, thereby preventing the benzene liquid from excessively gathering in the retaining cylinder and causing the liquid level maintaining module to be unable to perform the liquid level maintaining work normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 What is shown is a schematic diagram of the overall structure of the embodiment;

[0034] Figure 2 Shown is a front view of a benzene storage tank in an embodiment;

[0035] Figure 3 Shown is a front cross-sectional view of a benzene storage tank in an embodiment;

[0036] Figure 4 Shown is a diagram of the installation position of the reflux assembly in the embodiment;

[0037] Figure 5 What is shown is a moving state diagram of the reflux component in the embodiment;

[0038] Figure 6 Shown are structural diagrams of various parts of the discharge member in the embodiment.

[0039] In the figure: 10, purification tower; 11, filler; 12, acid inlet pipe; 13, benzene inlet pipe; 14, drain pipe 1; 15, drain pipe 2; 20, benzene storage tank; 21, liquid inlet; 22, liquid outlet; 31, retaining cylinder; 32, partition; 33, reflux pipe; 34, reflux assembly; 341, movable frame; 342, piston plate; 343, return spring; 344, through hole; 345, closing plate; 35, discharge member; 351, mounting plate; 352, discharge port; 353, screw rod; 354, slider; 355, piston block; 356, follower plate; 357, connecting spring; 358, gear; 359, discharge pipe; 40, acid-benzene separator; 50, waste acid separator; 60, waste acid re-separator; 70, waste acid transfer tank. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings of the specification.

[0041] Example

[0042] Figure 1-Figure 5 A device for separating waste acid from mixed dinitrobenzene production, comprising:

[0043] A purification tower 10, wherein a packing 11 is disposed inside the purification tower 10, wherein an acid inlet pipe 12 for injecting waste acid liquid and a benzene inlet pipe 13 for injecting benzene liquid are disposed at the top and bottom of the packing 11, respectively. Due to the different densities of the two, the waste acid liquid is dispersed and flows downward after entering, and the benzene liquid flows from bottom to top after entering, and the two form a countercurrent extraction in the packing 11 to remove nitrates in the waste acid;

[0044] The benzene storage tank 20 is located at the top of the purification tower 10 and continuously supplies benzene liquid to the purification tower 10 by utilizing the high head difference. A liquid level maintaining module is arranged inside the benzene storage tank 20. An external supply device injects benzene liquid from a liquid inlet 21 on one side of the benzene storage tank 20. After a portion of the benzene liquid is diverted by the liquid level maintaining component to keep the liquid level at the same height, the liquid enters the benzene inlet pipe 13 through a pipeline from a liquid outlet 22 at the bottom of the benzene storage tank 20.

[0045] A purification tower 10 with a filler 11 is added, and benzene is used as a continuous phase and waste acid is used as a dispersed phase to enter the purification tower 10. By utilizing the density difference between the waste acid liquid and the benzene liquid, the waste acid liquid is dispersed at the top of the tower and flows downward, while the benzene liquid continuously enters the bottom of the purification tower 10 and flows upward by means of the high position difference, and the two form a countercurrent extraction to remove the nitrate in the waste acid. Thus, the nitrate content in the waste acid is reduced from 0.6% to 0.8% before separation to less than 0.1% after separation, and a large amount of nitrate can be recovered, avoiding the pollution of the alkaline water inside the tail gas absorption tower caused by the nitrate flowing into the tail gas absorption tower, and reducing the difficulty of subsequent treatment.

[0046] A separation method for a waste acid separation device for mixed dinitrobenzene production comprises the following steps:

[0047] S1, supply benzene liquid;

[0048] The benzene liquid in the benzene storage tank 20 is continuously injected into the purification tower 10 from the bottom of the purification tower 10 by using a high head difference, and the liquid level maintaining module in the benzene storage tank 20 keeps the internal liquid level at the same height for continuous constant flow supply;

[0049] S2, injecting waste acid;

[0050] The waste acid liquid is injected into the purification tower 10 from the top of the purification tower 10, and the waste acid liquid is dispersed around when flowing through the top of the purification tower 10;

[0051] S3, countercurrent extraction;

[0052] By utilizing the density difference between the waste acid liquid and the benzene liquid, the benzene liquid flowing upward and the waste acid liquid flowing downward form a countercurrent extraction to remove nitrates, the mixed liquid flowing upward flows out from the top of the purification tower 10 and enters the S4 step, and the mixed liquid flowing downward flows out from the bottom of the purification tower 10 and enters the S5 step;

[0053] S4, acid benzene separation;

[0054] The mixed liquid flowing out from the top of the purification tower 10 enters the acid-benzene separator 40, and after the benzene in the mixed liquid is separated, it enters step S5;

[0055] S5, organic phase separation;

[0056] The mixed liquid flowing out from the bottom of the purification tower 10 or the mixed liquid output from the acid-benzene separator 40 is sent to the waste acid separator 50, so that the organic phase in the mixed liquid is separated to obtain acid liquid.

[0057] Also included: S6, acid concentration;

[0058] The acid solution flowing out of the waste acid separator 50 enters the waste acid re-separator 60 and is further purified or concentrated for effective recovery and reuse.

[0059] Figure 3-Figure 5 In the embodiment, the liquid level maintaining module includes a maintaining cylinder 31 and a reflux assembly 34, a partition 32 is provided in the middle of the maintaining cylinder 31, a reflux pipe 33 is provided on one side of the partition 32, one end of the reflux pipe 33 passes through the maintaining cylinder 31 and extends to the outside of the maintaining cylinder 31, the partition 32 divides the maintaining cylinder 31 into a diversion bin and a reflux bin, the internal liquid level of the benzene storage tank 20 is flush with the top of the diversion bin, the reflux assembly 34 pushes the benzene liquid in the diversion bin to raise the liquid level in the reflux bin, and the benzene liquid is discharged from the maintaining cylinder 31 along the reflux pipe 33 to replenish the liquid level.

[0060] The reflux assembly 34 includes a movable frame 341 and a piston plate 342. The movable frame 341 is connected to a driving member. In the present technical solution, the driving member is a cylinder with adjustable stroke. The driving member drives the movable frame 341 to move with variable stroke non-periodically. A plurality of return springs 343 are arranged at the bottom of the piston plate 342. A plurality of through holes 344 are opened in the middle of the piston plate 342. A plurality of closing plates 345 corresponding to the through holes 344 are arranged at the bottom of the movable frame 341.

[0061] After the external supply equipment injects the benzene liquid into the benzene storage tank 20 from the liquid inlet 21, the excess benzene liquid enters the retaining cylinder 31 from the top of the diversion bin, so that the liquid level of the benzene liquid is kept at the same height. At this time, the driving member drives the movable frame 341 to move non-periodically in the vertical direction. The movable frame 341 contacts the piston plate 342 and inserts the closing plate 345 into the through hole 344 to seal the piston plate 342. The movable frame 341 can push the closing plate 345 to move, and the return spring 343 is compressed and deformed accordingly. The benzene liquid in the diversion bin is pressed down along the movement of the closing plate 345 to raise the liquid level inside the reflux bin, and the rising benzene liquid is discharged from the retaining cylinder 31 along the reflux pipe 33 to replenish the liquid level inside the benzene storage tank 20.

[0062] The external supply equipment supplies a volume greater than the outflow volume of the benzene liquid, and the excess benzene liquid will flow from the diversion bin into the retaining cylinder 31, which can ensure that the liquid level height of the benzene storage tank 20 is consistent, thereby making the flow rate of the benzene liquid entering the purification tower 10 consistent, and by moving the piston plate 342 non-periodically, the liquid level inside the reflux bin is raised by utilizing the communicating vessel principle, so that part of the liquid is discharged from the retaining cylinder 31 along the reflux pipe 33, thereby preventing the benzene liquid from being retained in the retaining cylinder 31 for too long, and effectively replenishing the liquid level height inside the benzene storage tank 20, further ensuring the supply effect of the benzene liquid.

[0063] Figure 3-Figure 5 In the embodiment, the reflux assembly 34 also includes a discharge member 35, which includes a discharge pipe 359 and a mounting plate 351 fixedly connected to the partition 32. The discharge pipe 359 is located on the inner surface of the retaining cylinder 31 and is provided with a discharge port 352. One end of the discharge pipe 359 passes through the retaining cylinder 31 and the benzene storage tank 20 and extends to the outside, and the end of the discharge pipe 359 is connected to the storage box of the external supply equipment through a pipeline. A screw rod 353 is rotatably inserted in the middle of the discharge pipe 359, and a slider 354 is threadedly sleeved on one end of the screw rod 353. A piston block 355 is provided at one end of the slider 354. The piston block 355 reciprocates inside the discharge pipe 359 to control the opening and closing of the discharge port 352.

[0064] A follower plate 356 is movably inserted inside the mounting plate 351 , a connecting spring 357 is fixedly connected between the follower plate 356 and the mounting plate 351 , a gear 358 is meshedly connected to the middle of the follower plate 356 , and the gear 358 is fixedly connected to the screw rod 353 .

[0065] When the piston plate 342 moves a distance beyond the reflux position, the piston plate 342 contacts the follower plate 356 and moves it downward, and the connecting spring 357 is stretched and deformed accordingly. The gear 358 drives the screw rod 353 to rotate as the follower plate 356 moves, and the slider 354 moves accordingly to move the piston block 355 away from the discharge port 352 position. The benzene liquid inside the cylinder 31 can enter the discharge pipe 359 through the discharge port 352 position, thereby discharging the excess benzene liquid for collection.

[0066] The set discharge member 35 uses the movement of the piston plate 342 as the power to push the piston block 355 to leave the discharge port 352 position, and the benzene liquid inside the retaining cylinder 31 can enter the discharge pipe 359 through the discharge port 352 position and be discharged, thereby preventing the benzene liquid from excessively gathering in the retaining cylinder 31 and causing the liquid level maintaining module to be unable to perform the liquid level maintaining work normally.

[0067] Figure 1 The method further includes: an acid-benzene separator 40, wherein the output end of the acid-benzene separator 40 is connected to a drain pipe 14 at the top of the purification tower 10 through a pipeline, and the acid-benzene separator 40 is used to separate acid and benzene from the mixed liquid.

[0068] It also includes: a waste acid separator 50, the input end of the waste acid separator 50 is respectively connected to the bottom discharge pipe 15 of the purification tower 10 and the input end of the acid-benzene separator 40, and the waste acid separator 50 is used to separate the acid and organic phase from the mixed liquid output from the purification tower 10 or the mixed liquid output from the acid-benzene separator 40.

[0069] The invention also includes: a waste acid re-separator 60 and a waste acid transfer tank 70 connected to the waste acid re-separator 60, wherein the waste acid re-separator 60 and the waste acid transfer tank 70 are both connected to the output ends of the acid-benzene separator 40 and the waste acid separator 50 through pipelines, and the mixed liquid output from the output ends of the acid-benzene separator 40 and the mixed liquid output from the output ends of the waste acid separator 50 can be directly input into the waste acid re-separator 60, or transferred through the waste acid transfer tank 70 and then input into the waste acid re-separator 60.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A device for separating waste acid from mixed dinitrobenzene production, characterized in that: include: A purification tower (10), wherein a packing (11) is arranged inside the purification tower (10), and an acid inlet pipe (12) for injecting waste acid liquid and a benzene inlet pipe (13) for injecting benzene liquid are respectively arranged at the top and bottom of the packing (11) of the purification tower (10). Due to the different densities of the two, the waste acid liquid is dispersed and flows downward after entering, and the benzene liquid flows from bottom to top after entering, and the two form a countercurrent extraction in the packing (11) to remove nitrates in the waste acid; A benzene storage tank (20), the benzene storage tank (20) being located at the top of the purification tower (10) and continuously supplying benzene liquid to the purification tower (10) by utilizing a high head difference, the benzene storage tank (20) being provided with a liquid level maintaining module inside, an external supply device injecting benzene liquid from a liquid inlet (21) on one side of the benzene storage tank (20), and after a portion of the benzene liquid is diverted by the liquid level maintaining component so that the liquid level is maintained at the same height, the benzene liquid enters the benzene inlet pipe (13) through a pipeline from a liquid outlet (22) at the bottom of the benzene storage tank (20); The liquid level maintaining module comprises a holding cylinder (31) and a reflux assembly (34); a partition (32) is provided in the middle of the holding cylinder (31); a reflux pipe (33) is provided on one side of the partition (32); one end of the reflux pipe (33) penetrates the holding cylinder (31) and extends to the outside of the holding cylinder (31); the partition (32) divides the holding cylinder (31) into a diversion bin and a reflux bin; the liquid level inside the benzene storage tank (20) is flush with the top of the diversion bin; the reflux assembly (34) uses the principle of a communicating vessel to push the benzene liquid inside the diversion bin so that the liquid level in the reflux bin is raised; and the benzene liquid is discharged from the holding cylinder (31) along the reflux pipe (33) to replenish the liquid level; The reflux assembly (34) comprises a movable frame (341) and a piston plate (342); the movable frame (341) is connected to a driving member, and the driving member drives the movable frame (341) to move in a variable range in a non-periodic manner; a plurality of return springs (343) are arranged at the bottom of the piston plate (342); a plurality of through holes (344) are opened in the middle of the piston plate (342); and a plurality of closing plates (345) corresponding to the through holes (344) are arranged at the bottom of the movable frame (341).

2. A mixed dinitrobenzene production waste acid separation device according to claim 1, characterized in that: The reflux assembly (34) further comprises a discharge member (35), the discharge member (35) comprising a discharge pipe (359) and a mounting plate (351) fixedly connected to the partition (32); the discharge pipe (359) is located on the inner surface of the retaining cylinder (31) and is provided with a discharge port (352); one end of the discharge pipe (359) penetrates the retaining cylinder (31) and the benzene storage tank (20) and extends to the outside, and the end of the discharge pipe (359) is connected to a storage box of an external supply device through a pipeline; a screw rod (353) is rotatably inserted in the middle of the discharge pipe (359); a slider (354) is threadedly sleeved on one end of the screw rod (353); a piston block (355) is provided at one end of the slider (354); the piston block (355) reciprocates inside the discharge pipe (359) to control the opening and closing of the discharge port (352).

3. A mixed dinitrobenzene production waste acid separation device according to claim 2, characterized in that: A follower plate (356) is movably inserted inside the mounting plate (351), a connecting spring (357) is fixedly connected between the follower plate (356) and the mounting plate (351), a gear (358) is meshingly connected in the middle of the follower plate (356), and the gear (358) is fixedly connected to the screw rod (353).

4. A mixed dinitrobenzene production waste acid separation device according to claim 1, characterized in that: Also includes: An acid-benzene separator (40), wherein the output end of the acid-benzene separator (40) is connected to a first drain pipe (14) at the top of the purification tower (10) via a pipeline, and the acid-benzene separator (40) is used to separate acid and benzene from the mixed liquid.

5. A mixed dinitrobenzene production waste acid separation device according to claim 4, characterized in that: Also includes: A waste acid separator (50), wherein the input end of the waste acid separator (50) is respectively connected to the second drainage pipe (15) at the bottom of the purification tower (10) and the input end of the acid-benzene separator (40), and the waste acid separator (50) is used to separate the acid and the organic phase from the mixed liquid output from the purification tower (10) or the mixed liquid output from the acid-benzene separator (40).

6. A mixed dinitrobenzene production waste acid separation device according to claim 5, characterized in that: Also includes: A waste acid re-separator (60) and a waste acid transfer tank (70) connected to the waste acid re-separator (60); the waste acid re-separator (60) and the waste acid transfer tank (70) are both connected to an output end of an acid-benzene separator (40) and an output end of a waste acid separator (50) through pipelines; the mixed liquid output from the output end of the acid-benzene separator (40) and the mixed liquid output from the output end of the waste acid separator (50) can be directly input into the waste acid re-separator (60), or transferred through the waste acid transfer tank (70) and then input into the waste acid re-separator (60).

7. The separation method according to any one of claims 1 to 6, wherein the separation method comprises: The following steps are included: S1, supply benzene liquid; The benzene liquid in the benzene storage tank (20) is continuously injected into the purification tower (10) from the bottom of the purification tower (10) by using a high head difference, and the liquid level maintaining module in the benzene storage tank (20) maintains the internal liquid level at the same height for continuous constant flow supply; S2, injecting waste acid; Injecting the waste acid liquid into the purification tower (10) from the top of the purification tower (10), and the waste acid liquid is dispersed in all directions when flowing through the top of the purification tower (10); S3, countercurrent extraction; By utilizing the density difference between the waste acid liquid and the benzene liquid, the benzene liquid flowing upward and the waste acid liquid flowing downward form a countercurrent extraction to remove the nitrates, the mixed liquid flowing upward flows out from the top of the purification tower (10) and enters the S4 step, and the mixed liquid flowing downward flows out from the bottom of the purification tower (10) and enters the S5 step; S4, acid benzene separation; The mixed liquid flowing out from the top of the purification tower (10) enters the acid-benzene separator (40), and after the benzene in the mixed liquid is separated, it enters step S5; S5, organic phase separation; The mixed liquid flowing out from the bottom of the purification tower (10) or the mixed liquid output from the acid-benzene separator (40) is sent to the waste acid separator (50) to separate the organic phase in the mixed liquid to obtain acid liquid.

8. The separation method according to claim 7, characterized in that: Also includes: S6, acid concentration; The acid solution flowing out of the waste acid separator (50) enters the waste acid re-separator (60) and is further purified or concentrated for effective recovery and reuse.

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