Hydrogen chloride and sulfur dioxide tail gas recycling system

Abstract

The utility model discloses a hydrogen chloride and sulfur dioxide tail gas recycling system which comprises a falling film absorption tower group, a buffer tank group, a falling film tower bottom pump group, a water spray tower group, an alkali spray tower group, a stirring kettle group, a crystallization kettle and a centrifugal machine. According to different solubility of hydrogen chloride and sulfur dioxide in water, a small amount of sulfur dioxide in water is brought into the alkali spray tower in an air-blowing mode to form sulfite and chlorate, and recycled hydrochloric acid is obtained by stirring kettle liquid. And the formed sulfite and chlorate are crystallized and centrifuged by adjusting the temperature to obtain the recovered sulfite, so that the efficient utilization of the tail gas is realized on the premise of ensuring that the treated tail gas reaches the emission standard.

Description

Technical Field

[0001] This utility model belongs to the field of exhaust gas treatment technology, specifically relating to a system for recovering and reusing hydrogen chloride and sulfur dioxide exhaust gases. Background Technology

[0002] Currently, various reactions are involved in chemical production. Among them, thionyl chloride is used as a chlorinating reactant in the acyl chloride reaction. During the reaction, a large amount of hydrogen chloride and sulfur dioxide waste gas is generated. Direct emission of these gases will lead to acid rain and environmental pollution. Traditional treatment methods often use graphite falling film absorption and alkaline scrubbing to treat the waste gas before emission. The absorbent after absorption is often neutralized as wastewater, generating a large amount of solid waste such as miscellaneous salts, which increases the treatment load of the three wastes (waste gas, wastewater, and solid waste).

[0003] Therefore, this utility model proposes a hydrogen chloride and sulfur dioxide tail gas recovery and reuse system, which realizes the recovery of hydrogen chloride and sulfite and reduces the generation of downstream waste salt. Utility Model Content

[0004] In view of the problems existing in the prior art, the purpose of this utility model is to provide a system for recovering and reusing hydrogen chloride and sulfur dioxide tail gas, so as to achieve efficient utilization of tail gas while ensuring that the treated tail gas meets the emission standards.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A system for recovering and reusing hydrogen chloride and sulfur dioxide tail gas includes a falling film absorption tower group, a buffer tank group, a falling film tower bottom pump group, a water spray tower group, an alkali spray tower group, a stirred tank group, a crystallization tank, and a centrifuge. The falling film absorption tower group includes a first-stage falling film absorption tower and a fourth-stage falling film absorption tower. The buffer tank group includes a first-stage buffer tank and a fourth-stage buffer tank. The falling film tower bottom pump group includes a first-stage falling film absorption tower bottom pump and a fourth-stage falling film absorption tower bottom pump.

[0007] The gas outlet on the side of the first-stage falling film absorption tower is connected to the gas inlet at the top of the fourth-stage falling film absorption tower via a pipeline. The gas outlet on the side of the fourth-stage falling film absorption tower is connected to the air inlet of the water spray tower assembly via a pipeline. The gas outlet of the water spray tower assembly is connected to the air inlet of the alkali spray tower assembly via a pipeline.

[0008] The liquid outlet at the bottom of the first-stage falling film absorber is connected to the liquid inlet at the top of the first buffer tank via a pipeline. The liquid outlet on the side of the first buffer tank is connected to the liquid inlet of the bottom pump of the first-stage falling film absorber via a pipeline. The liquid outlet of the bottom pump of the first-stage falling film absorber is divided into two paths: one path is connected to the liquid inlet on the side of the first-stage falling film absorber via a pipeline, and the other path is connected to the liquid inlet of the reactor group via a pipeline. The gas outlet of the reactor group is connected to the gas inlet of the water spray tower group via a pipeline.

[0009] The water spray tower group has three liquid outlets: the first is that the liquid outlet of the water spray tower group is connected to the liquid inlet of the fourth buffer tank through a pipeline, and the bottom liquid outlet of the fourth-stage falling film absorption tower is connected to the top liquid inlet of the fourth buffer tank through a pipeline; the side liquid outlet of the fourth buffer tank is connected to the bottom pump liquid inlet of the fourth-stage falling film absorption tower through a pipeline, and the bottom pump liquid outlet of the fourth-stage falling film absorption tower has two branches: one is that the bottom pump liquid outlet of the fourth-stage falling film absorption tower is connected to the side liquid inlet of the fourth-stage falling film absorption tower through a pipeline, and the other is that the bottom pump liquid outlet of the fourth-stage falling film absorption tower is connected to the liquid inlet of the first buffer tank through a pipeline;

[0010] The liquid outlet of the alkali spray tower group is divided into three paths. The first path is: the liquid outlet of the alkali spray tower group is connected to the liquid inlet at the top of the crystallization kettle through a pipeline. The liquid in the crystallization kettle is connected to the liquid inlet at the top of the centrifuge through a pipeline.

[0011] Furthermore, it includes a water spray tower bottom pump set, which includes a first-stage water spray tower bottom pump and a second-stage water spray tower bottom pump, and the water spray tower set includes a first-stage water spray tower and a second-stage water spray tower.

[0012] The gas outlet at the top of the first-stage water spray tower is connected to the gas inlet on the side of the second-stage water spray tower via a pipeline, and the gas outlet on the side of the fourth-stage falling film absorption tower is connected to the gas inlet on the side of the first-stage water spray tower via a pipeline.

[0013] The second-stage water spray tower has a fresh water inlet on its side, and its side liquid outlet is connected to the liquid inlet of the bottom pump of the second-stage water spray tower through a pipeline. The liquid outlet of the bottom pump of the second-stage water spray tower is divided into three paths: the first path is connected to the liquid inlet on the side of the first-stage water spray tower through a pipeline; the second path is connected to the first side liquid inlet of the second-stage water spray tower through a pipeline; and the third path is connected to the second side liquid inlet of the second-stage water spray tower through a pipeline.

[0014] Furthermore, the liquid outlet on the side of the first-stage water spray tower is connected to the liquid inlet of the bottom pump of the first-stage water spray tower via a pipeline. The liquid outlet of the bottom pump of the first-stage water spray tower is divided into three paths: the first path is connected to the liquid inlet of the fourth buffer tank via a pipeline; the second path is connected to the first liquid inlet on the side of the first-stage water spray tower via a pipeline; and the third path is connected to the second liquid inlet on the side of the first-stage water spray tower via a pipeline.

[0015] Furthermore, the second and third pipelines of the liquid outlet of the bottom pump of the first-stage water spray tower are respectively connected to their corresponding spray heads;

[0016] The second and third pipelines of the liquid outlet of the bottom pump of the second-stage water spray tower are respectively connected to their corresponding spray heads.

[0017] Furthermore, it includes a bottom pump unit for alkali spraying towers, which includes a primary alkali spraying tower bottom pump and a secondary alkali spraying tower bottom pump. The alkali spraying tower group includes a primary alkali spraying tower and a secondary alkali spraying tower. Both the primary and secondary alkali spraying towers are provided with alkali inlets on their sides.

[0018] The gas outlet at the top of the second-stage water spray tower is connected to the gas inlet on the side of the first-stage alkali spray tower via a pipeline, and the gas outlet at the top of the first-stage alkali spray tower is connected to the gas inlet on the side of the second-stage alkali spray tower via a pipeline.

[0019] The liquid outlet on the side of the primary alkali spray tower is connected to the liquid inlet of the bottom pump of the primary alkali spray tower via a pipeline. The liquid outlet of the bottom pump of the primary alkali spray tower is divided into three paths: the first path is connected to the liquid inlet at the top of the crystallization vessel via a pipeline; the second path is connected to the first liquid inlet on the side of the primary alkali spray tower via a pipeline; and the third path is connected to the second liquid inlet on the side of the primary alkali spray tower via a pipeline.

[0020] Furthermore, the liquid outlet on the side of the secondary alkali spray tower is connected to the liquid inlet of the bottom pump of the secondary alkali spray tower via a pipeline. The liquid outlet of the bottom pump of the secondary alkali spray tower is divided into three paths: the first path is connected to the liquid inlet at the top of the crystallization vessel via a pipeline; the second path is connected to the first liquid inlet on the side of the secondary alkali spray tower via a pipeline; and the third path is connected to the second liquid inlet on the side of the secondary alkali spray tower via a pipeline.

[0021] Furthermore, the falling film absorption tower group includes a second-stage falling film absorption tower, the falling film tower bottom pump group includes a second-stage falling film absorption tower bottom pump, and the buffer tank group includes a second buffer tank;

[0022] The gas outlet on the side of the first-stage falling film absorption tower is connected to the gas inlet at the top of the second-stage falling film absorption tower via a pipeline, and the gas outlet on the side of the second-stage falling film absorption tower is connected to the gas inlet at the top of the fourth-stage falling film absorption tower via a pipeline.

[0023] The bottom liquid outlet of the second-stage falling film absorber is connected to the liquid inlet of the second buffer tank via a pipeline. The liquid outlet of the second buffer tank is connected to the liquid inlet of the bottom pump of the second-stage falling film absorber via a pipeline. The liquid outlet of the bottom pump of the second-stage falling film absorber is divided into two paths: one path is connected to the liquid inlet at the top of the first buffer tank via a pipeline, and the other path is connected to the liquid inlet on the side of the second-stage falling film absorber via a pipeline.

[0024] The liquid outlet of the bottom pump of the fourth-stage falling film absorber is connected to the liquid inlet at the top of the second buffer tank via a pipeline.

[0025] Furthermore, the falling film absorption tower group includes a third-stage falling film absorption tower, the falling film tower bottom pump group includes a third-stage falling film absorption tower bottom pump, and the buffer tank group includes a third buffer tank;

[0026] The gas outlet on the side of the first-stage falling film absorption tower is connected to the gas inlet at the top of the second-stage falling film absorption tower via a pipeline; the gas outlet on the side of the second-stage falling film absorption tower is connected to the gas inlet at the top of the third-stage falling film absorption tower via a pipeline; and the gas outlet on the side of the third-stage falling film absorption tower is connected to the gas inlet at the top of the fourth-stage falling film absorption tower via a pipeline.

[0027] The bottom liquid outlet of the third-stage falling film absorption tower is connected to the liquid inlet of the third buffer tank via a pipeline. The liquid outlet of the third buffer tank is connected to the liquid inlet of the bottom pump of the third-stage falling film absorption tower via a pipeline. The liquid outlet of the bottom pump of the third-stage falling film absorption tower is divided into two paths: one path is connected to the liquid inlet at the top of the second buffer tank via a pipeline, and the other path is connected to the liquid inlet on the side of the third-stage falling film absorption tower via a pipeline.

[0028] The liquid outlet of the bottom pump of the fourth-stage falling film absorber is connected to the liquid inlet at the top of the third buffer tank via a pipeline.

[0029] Furthermore, the stirred tank group includes stirred tank one and stirred tank two. Compressed air is introduced into the bottom of stirred tank one and stirred tank two. The top gas outlet of stirred tank one and the top gas outlet of stirred tank two are both connected to the side gas inlet of the first-stage water spray tower through pipelines. The pipeline connecting the liquid outlet of the bottom pump of the first-stage falling film absorption tower to the liquid inlet of the reaction tank group is divided into two lines: one line is connected to the liquid inlet of stirred tank one, and the other line is connected to the liquid inlet of stirred tank two.

[0030] Furthermore, the temperature inside each falling film absorption tower in the falling film absorption tower group is 30~50℃; the temperature inside each stirred tank during bubbling is 5-40℃; the temperature inside the crystallization tank is 5-15℃; and the centrifugation temperature of the centrifuge is 5-15℃.

[0031] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0032] 1) This utility model can effectively absorb hydrogen chloride and sulfur dioxide waste gas through falling film absorption tower group and water spray tower group. Dissolved sulfur dioxide is blown out from the stirred tank group with air, and hydrochloric acid solution can be recovered from the tank liquid. The waste gas blown out by air passes through alkaline spray tower group, crystallization tank and centrifuge to utilize the solubility trend of sulfite and chloride with temperature change, cool and crystallize to recover the by-product sulfite, and achieve efficient utilization of the exhaust gas while ensuring that the treated exhaust gas meets the emission standards.

[0033] 2) This utility model sets up a four-stage falling film absorption and a two-stage water absorption to improve the absorption rate of hydrogen chloride and reduce the generation of chloride salts in the downstream alkali absorption tower. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall system structure of this utility model.

[0035] In the diagram: 1. First-stage falling film absorption tower; 2. Second-stage falling film absorption tower; 3. Third-stage falling film absorption tower; 4. Fourth-stage falling film absorption tower; 5. First-stage water spray tower; 6. Second-stage water spray tower; 7. First-stage alkali spray tower; 8. Second-stage alkali spray tower; 9. Bottom pump of the first-stage falling film absorption tower; 10. Bottom pump of the second-stage falling film absorption tower; 11. Bottom pump of the third-stage falling film absorption tower; 12. Bottom pump of the fourth-stage falling film absorption tower; 13. Bottom pump of the first-stage water spray tower; 14. Bottom pump of the second-stage water spray tower; 15. Bottom pump of the first-stage alkali spray tower; 16. Bottom pump of the second-stage alkali spray tower; 17. Stirring vessel one; 18. Stirring vessel two; 19. Crystallization vessel; 20. Centrifuge; 21. First buffer tank; 22. Second buffer tank; 23. Third buffer tank; 24. Fourth buffer tank. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the scope described herein.

[0037] like Figure 1 As shown, a hydrogen chloride and sulfur dioxide tail gas recovery and reuse system includes a falling film absorption tower group, a buffer tank group, a falling film tower bottom pump group, a water spray tower group, an alkali spray tower group, a stirred tank group, a crystallization tank 19, and a centrifuge 20.

[0038] As the first embodiment of this utility model, when the falling film absorption tower group consists of two falling film absorption towers connected in series, the falling film absorption tower group includes a first-stage falling film absorption tower 1 and a fourth-stage falling film absorption tower 4, the buffer tank group includes a first buffer tank 21 and a fourth buffer tank 24, and the falling film tower bottom pump group includes a first-stage falling film absorption tower bottom pump 9 and a fourth-stage falling film absorption tower bottom pump 12.

[0039] The gas outlet on the side of the first-stage falling film absorption tower 1 is connected to the gas inlet at the top of the fourth-stage falling film absorption tower 4 via a pipeline. The gas outlet on the side of the fourth-stage falling film absorption tower 4 is connected to the air inlet of the water spray tower assembly via a pipeline. The gas outlet of the water spray tower assembly is connected to the air inlet of the alkali spray tower assembly via a pipeline.

[0040] The bottom liquid outlet of the first-stage falling film absorber 1 is connected to the top liquid inlet of the first buffer tank 21 via a pipeline. The side liquid outlet of the first buffer tank 21 is connected to the liquid inlet of the bottom pump 9 of the first-stage falling film absorber via a pipeline. The liquid outlet of the bottom pump 9 of the first-stage falling film absorber is divided into two paths: one path is connected to the side liquid inlet of the first-stage falling film absorber 1 via a pipeline, and the other path is connected to the liquid inlet of the reactor group via a pipeline. The gas outlet of the reactor group is connected to the gas inlet of the water spray tower group via a pipeline.

[0041] The liquid outlet of the water spray tower group is divided into three paths: The first path is: the liquid outlet of the water spray tower group is connected to the liquid inlet of the fourth buffer tank 24 through a pipeline, and the liquid outlet at the bottom of the fourth-stage falling film absorption tower 4 is connected to the liquid inlet at the top of the fourth buffer tank 24 through a pipeline; the liquid outlet on the side of the fourth buffer tank 24 is connected to the liquid inlet of the bottom pump 12 of the fourth-stage falling film absorption tower through a pipeline, and the liquid outlet of the bottom pump 12 of the fourth-stage falling film absorption tower is divided into two paths: one path is: the liquid outlet of the bottom pump 12 of the fourth-stage falling film absorption tower is connected to the liquid inlet on the side of the fourth-stage falling film absorption tower 4 through a pipeline, and the other path is: the liquid outlet of the bottom pump 12 of the fourth-stage falling film absorption tower is connected to the liquid inlet of the first buffer tank 21 through a pipeline.

[0042] The liquid outlet of the alkali spray tower group is divided into three paths. The first path is: the liquid outlet of the alkali spray tower group is connected to the liquid inlet at the top of the crystallizer 19 through a pipeline, and the liquid in the crystallizer 19 is connected to the liquid inlet at the top of the centrifuge 20 through a pipeline.

[0043] Furthermore, the system of this utility model also includes a first-stage water spray tower bottom pump 13 and a second-stage water spray tower bottom pump 14, and the water spray tower group includes a first-stage water spray tower 5 and a second-stage water spray tower 6.

[0044] The gas outlet at the top of the first-stage water spray tower 5 is connected to the gas inlet on the side of the second-stage water spray tower 6 via a pipeline, and the gas outlet on the side of the fourth-stage falling film absorption tower 4 is connected to the gas inlet on the side of the first-stage water spray tower 5 via a pipeline.

[0045] The second-stage water spray tower 6 has a fresh water inlet on its side. Its side liquid outlet is connected to the liquid inlet of the second-stage water spray tower bottom pump 14 via a pipeline. The liquid outlet of the second-stage water spray tower bottom pump 14 is divided into three paths: the first path is connected to the liquid inlet on the side of the first-stage water spray tower 5 via a pipeline; the second path is connected to the first liquid inlet on the side of the second-stage water spray tower 6 via a pipeline; and the third path is connected to the second liquid inlet on the side of the second-stage water spray tower 6 via a pipeline. The second and third pipelines of the liquid outlet of the second-stage water spray tower bottom pump 14 are respectively connected to their corresponding spray heads.

[0046] The liquid outlet on the side of the first-stage water spray tower 5 is connected to the liquid inlet of the first-stage water spray tower bottom pump 13 via a pipeline. The liquid outlet of the first-stage water spray tower bottom pump 13 is divided into three paths: the first path is connected to the liquid inlet of the fourth buffer tank 24 via a pipeline; the second path is connected to the first liquid inlet on the side of the first-stage water spray tower 5 via a pipeline; and the third path is connected to the second liquid inlet on the side of the first-stage water spray tower 5 via a pipeline. The second and third pipelines of the liquid outlet of the first-stage water spray tower bottom pump 13 are respectively connected to their corresponding spray heads.

[0047] The system of this utility model includes a primary alkali spray tower bottom pump 15 and a secondary alkali spray tower bottom pump 16. The alkali spray tower group includes a primary alkali spray tower 7 and a secondary alkali spray tower 8. Both the primary alkali spray tower 7 and the secondary alkali spray tower are provided with alkali inlets on their sides.

[0048] The top gas outlet of the second-stage water spray tower 6 is connected to the side gas inlet of the first-stage alkali spray tower 7 via a pipeline, and the top gas outlet of the first-stage alkali spray tower 7 is connected to the side gas inlet of the second-stage alkali spray tower 8 via a pipeline.

[0049] The liquid outlet on the side of the primary alkali spray tower 7 is connected to the liquid inlet of the primary alkali spray tower bottom pump 15 via a pipeline. The liquid outlet of the primary alkali spray tower bottom pump 15 is divided into three paths: the first path is connected to the liquid inlet at the top of the crystallization vessel 19 via a pipeline; the second path is connected to the first liquid inlet on the side of the primary alkali spray tower 7 via a pipeline; and the third path is connected to the second liquid inlet on the side of the primary alkali spray tower 7 via a pipeline.

[0050] The second and third pipelines at the liquid outlet on the side of the first-stage alkali spray tower 7 are connected to their corresponding spray heads.

[0051] The liquid outlet on the side of the secondary alkali spray tower 8 is connected to the liquid inlet of the bottom pump 16 of the secondary alkali spray tower via a pipeline. The liquid outlet of the bottom pump 16 of the secondary alkali spray tower is divided into three paths: the first path is connected to the liquid inlet at the top of the crystallization vessel 19 via a pipeline; the second path is connected to the first liquid inlet on the side of the secondary alkali spray tower 8 via a pipeline; and the third path is connected to the second liquid inlet on the side of the secondary alkali spray tower 8 via a pipeline.

[0052] The second and third pipelines at the liquid outlet on the side of the secondary alkali spray tower 8 are connected to their corresponding spray heads.

[0053] The stirred tank group includes stirred tank 17 and stirred tank 2 18. Both stirred tank 17 and stirred tank 2 18 have compressed air introduced into their bottoms. The top gas outlets of stirred tank 17 and stirred tank 2 18 are connected to the side gas inlet of the first-stage water spray tower 5 via pipelines. The pipeline connecting the liquid outlet of the bottom pump 9 of the first-stage falling film absorber to the liquid inlet of the reaction tank group is divided into two lines: one line is connected to the liquid inlet of stirred tank 17, and the other line is connected to the liquid inlet of stirred tank 2 18.

[0054] The temperature inside each falling film absorption tower in the falling film absorption tower group is 30~50℃; the temperature inside each stirred tank during bubbling is 5-40℃; the temperature inside the crystallizing tank is 5-15℃; and the centrifugal temperature of the centrifuge is 5-15℃.

[0055] As a second embodiment of the present invention, when the falling film absorption tower group consists of three falling film absorption towers connected in series, it further includes a second falling film absorption tower 2 based on embodiment 1, the falling film tower bottom pump group further includes a second falling film absorption tower bottom pump 10, and the buffer tank group further includes a second buffer tank 22.

[0056] The gas outlet on the side of the first-stage falling film absorption tower 1 is connected to the gas inlet at the top of the second-stage falling film absorption tower 2 via a pipeline, and the gas outlet on the side of the second-stage falling film absorption tower 2 is connected to the gas inlet at the top of the fourth-stage falling film absorption tower 4 via a pipeline.

[0057] The bottom liquid outlet of the second-stage falling film absorber 2 is connected to the liquid inlet of the second buffer tank 22 via a pipeline. The liquid outlet of the second buffer tank 22 is connected to the liquid inlet of the bottom pump 10 of the second-stage falling film absorber via a pipeline. The liquid outlet of the bottom pump 10 of the second-stage falling film absorber is divided into two paths: one path is connected to the liquid inlet at the top of the first buffer tank 21 via a pipeline, and the other path is connected to the liquid inlet on the side of the second-stage falling film absorber 2 via a pipeline.

[0058] The liquid outlet of the bottom pump 12 of the fourth-stage falling film absorber is connected to the liquid inlet at the top of the second buffer tank 22 via a pipeline.

[0059] As a third embodiment of the present invention, when the falling film absorption tower group consists of four falling film absorption towers connected in series, it further includes a third falling film absorption tower 3 based on embodiment 2, the falling film tower bottom pump group further includes a third falling film absorption tower bottom pump 11, and the buffer tank group further includes a third buffer tank 23.

[0060] The gas outlet on the side of the first-stage falling film absorption tower 1 is connected to the gas inlet at the top of the second-stage falling film absorption tower 2 via a pipeline. The gas outlet on the side of the second-stage falling film absorption tower 2 is connected to the gas inlet at the top of the third-stage falling film absorption tower 3 via a pipeline. The gas outlet on the side of the third-stage falling film absorption tower 3 is connected to the gas inlet at the top of the fourth-stage falling film absorption tower 4 via a pipeline.

[0061] The bottom liquid outlet of the third-stage falling film absorption tower 3 is connected to the liquid inlet of the third buffer tank 23 via a pipeline. The liquid outlet of the third buffer tank 23 is connected to the liquid inlet of the bottom pump 11 of the third-stage falling film absorption tower via a pipeline. The liquid outlet of the bottom pump 11 of the third-stage falling film absorption tower is divided into two paths: one path is connected to the liquid inlet at the top of the second buffer tank 22 via a pipeline, and the other path is connected to the liquid inlet on the side of the third-stage falling film absorption tower 3 via a pipeline.

[0062] The liquid outlet of the bottom pump 12 of the fourth-stage falling film absorber is connected to the liquid inlet at the top of the third buffer tank 23 via a pipeline.

[0063] The waste gas treatment process containing hydrogen chloride and sulfur dioxide using Example 3 is as follows:

[0064] A mixture of hydrogen chloride and sulfur dioxide gas enters sequentially through the waste gas pipeline into the first-stage falling film absorption tower 1, the second-stage falling film absorption tower 2, the third-stage falling film absorption tower 3, the fourth-stage falling film absorption tower 4, the first-stage water spray tower 5, and the second-stage water spray tower 6. Cooling water at 25-35℃ is used to maintain the temperature of the falling film absorption towers at 30-50℃. Fresh water enters the second-stage water spray tower 6, and after being sprayed and absorbed, it flows in reverse direction into the first-stage water spray tower 5, the fourth-stage falling film absorption tower 4, the third-stage falling film absorption tower 3, the second-stage falling film absorption tower 2, and the first-stage falling film absorption tower 1. The absorbent liquid that has absorbed hydrogen chloride and sulfur dioxide enters stirred tank 17 and stirred tank 28, switching between receiving absorbent liquids.

[0065] The compressed air pipeline is connected to the bottom of the stirred tank and a ring-type gas distribution device is used. After the stirred tank receives the absorbent, compressed air is introduced into the bottom of the tank to bubble inside the tank. The gas phase discharged from the stirred tank carries sulfur dioxide and some hydrogen chloride, which are mixed with the gas phase at the top of the second-stage water spray tower 6 and then connected to the first-stage alkali spray tower 7. After the compressed air bubbling is completed, the stirred tank contains a recyclable hydrochloric acid solution.

[0066] The unabsorbed mixed tail gas and the gas phase in the stirred tank are subjected to two-stage alkaline scrubbing to form chloride and sulfite. The mixed salt solution is sent to the crystallization tank 19 through the bottom pump 15 of the first-stage alkaline scrubbing tower and the bottom pump 16 of the second-stage alkaline scrubbing tower. The crystallization tank is controlled at 0-10℃ using low-temperature water. Since chloride crystallization is less affected by temperature, while sulfite crystallization is more sensitive to temperature, relatively pure sulfite crystals can be obtained by controlling the crystallization temperature.

[0067] After crystallization, the mixed salt solution enters centrifuge 20, where the centrifugation temperature is controlled at 0-10℃ using low-temperature water. Through multiple washing and centrifugation operations, relatively pure sulfite can be obtained as a byproduct. The centrifuged mother liquor is sent to the downstream MVR for desalination treatment.

Claims

1. A hydrogen chloride and sulfur dioxide tail gas recovery and reuse system characterized by The device comprises a falling film absorption tower group, a buffer tank group, a falling film tower bottom pump group, a water spray tower group, an alkali spray tower group, a stirring kettle group, a crystallization kettle (19) and a centrifugal machine (20), the falling film absorption tower group comprises a first-stage falling film absorption tower (1) and a fourth-stage falling film absorption tower (4), the buffer tank group comprises a first buffer tank (21) and a fourth buffer tank (24), and the falling film tower bottom pump group comprises a first-stage falling film absorption tower bottom pump (9) and a fourth-stage falling film absorption tower bottom pump (12); The gas outlet of the side of the first-stage falling film absorption tower (1) is connected with the gas inlet of the top of the fourth-stage falling film absorption tower (4) through a pipeline, the gas outlet of the side of the fourth-stage falling film absorption tower (4) is connected with the gas inlet of the water spray tower assembly through a pipeline, and the gas outlet of the water spray tower assembly is connected with the gas inlet of the alkali spray tower assembly through a pipeline. The liquid outlet of the bottom of the first-stage falling film absorption tower (1) is connected with the liquid inlet of the top of the first buffer tank (21) through a pipeline, the liquid outlet of the side of the first buffer tank (21) is connected with the liquid inlet of the first-stage falling film absorption tower bottom pump (9) through a pipeline, the liquid outlet of the first-stage falling film absorption tower bottom pump (9) is divided into two routes, one of which is connected with the liquid inlet of the side of the first-stage falling film absorption tower (1) through a pipeline, and the other of which is connected with the liquid inlet of the reaction kettle group through a pipeline. The liquid outlet of the water spray tower group is divided into three routes, the first route is connected with the liquid inlet of the top of the fourth buffer tank (24) through a pipeline, the liquid outlet of the bottom of the fourth-stage falling film absorption tower (4) is connected with the liquid inlet of the top of the fourth buffer tank (24) through a pipeline, the liquid outlet of the side of the fourth buffer tank (24) is connected with the liquid inlet of the fourth-stage falling film absorption tower bottom pump (12) through a pipeline, and the liquid outlet of the fourth-stage falling film absorption tower bottom pump (12) is divided into two routes, one of which is connected with the liquid inlet of the side of the fourth-stage falling film absorption tower (4) through a pipeline, and the other of which is connected with the liquid inlet of the first buffer tank (21) through a pipeline. The liquid outlet of the alkali spray tower group is divided into three routes, the first route is connected with the liquid inlet of the top of the crystallization kettle (19) through a pipeline, and the liquid outlet of the crystallization kettle (19) is connected with the liquid inlet of the top of the centrifugal machine (20) through a pipeline.

2. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 1, wherein The device comprises a water spray tower bottom pump group, the water spray tower bottom pump group comprises a first-stage water spray tower bottom pump (13) and a second-stage water spray tower bottom pump (14), and the water spray tower group comprises a first-stage water spray tower (5) and a second-stage water spray tower (6). The gas outlet of the top of the first-stage water spray tower (5) is connected with the gas inlet of the side of the second-stage water spray tower (6) through a pipeline, and the gas outlet of the side of the fourth-stage falling film absorption tower (4) is connected with the gas inlet of the side of the first-stage water spray tower (5) through a pipeline. The second-stage water spray tower (6) is provided with a fresh water inlet on the side, and a liquid outlet on the side is connected with a liquid inlet of a second-stage water spray tower bottom pump (14) through a pipeline.

3. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 2, wherein The liquid outlet on the side of the first-stage water spray tower (5) is connected with a liquid inlet of a first-stage water spray tower bottom pump (13) through a pipeline, and the liquid outlet of the first-stage water spray tower bottom pump (13) is divided into three routes: the first route is connected with a liquid inlet of a fourth buffer tank (24) through a pipeline; the second route is connected with a liquid inlet one on the side of the first-stage water spray tower (5) through a pipeline; and the third route is connected with a liquid inlet two on the side of the first-stage water spray tower (5) through a pipeline.

4. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 3, wherein The second pipeline and the third pipeline of the liquid outlet of the first-stage water spray tower bottom pump (13) are respectively connected with corresponding spray heads; The second pipeline and the third pipeline of the liquid outlet of the second-stage water spray tower bottom pump (14) are respectively connected with corresponding spray heads.

5. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 2, wherein The alkali spray tower bottom pump group comprises a first-stage alkali spray tower bottom pump (15) and a second-stage alkali spray tower bottom pump (16), the alkali spray tower group comprises a first-stage alkali spray tower (7) and a second-stage alkali spray tower (8), and the first-stage alkali spray tower (7) and the second-stage alkali spray tower (8) are both provided with alkali liquid inlets on the sides; The gas outlet on the top of the second-stage water spray tower (6) is connected with a gas inlet on the side of the first-stage alkali spray tower (7) through a pipeline, and the gas outlet on the top of the first-stage alkali spray tower (7) is connected with a gas inlet on the side of the second-stage alkali spray tower (8) through a pipeline; The liquid outlet on the side of the first-stage alkali spray tower (7) is connected with a liquid inlet of a first-stage alkali spray tower bottom pump (15) through a pipeline, and the liquid outlet of the first-stage alkali spray tower bottom pump (15) is divided into three routes: the first route is connected with a liquid inlet on the top of a crystallization kettle (19) through a pipeline; the second route is connected with a liquid inlet one on the side of the first-stage alkali spray tower (7) through a pipeline; and the third route is connected with a liquid inlet two on the side of the first-stage alkali spray tower (7) through a pipeline.

6. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 5, wherein The liquid outlet on the side of the second-stage alkali spray tower (8) is connected with a liquid inlet of a second-stage alkali spray tower bottom pump (16) through a pipeline, and the liquid outlet of the second-stage alkali spray tower bottom pump (16) is divided into three routes: the first route is connected with a liquid inlet on the top of the crystallization kettle (19) through a pipeline; the second route is connected with a liquid inlet one on the side of the second-stage alkali spray tower (8) through a pipeline; and the third route is connected with a liquid inlet two on the side of the second-stage alkali spray tower (8) through a pipeline.

7. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 1, wherein The falling film absorption tower group comprises a second-stage falling film absorption tower (2), the falling film tower bottom pump group comprises a second-stage falling film absorption tower bottom pump (10), and the buffer tank group comprises a second buffer tank (22). The gas outlet of the side part of the first falling film absorption tower (1) is connected with the gas inlet of the top part of the second falling film absorption tower (2) through a pipeline, and the gas outlet of the side part of the second falling film absorption tower (2) is connected with the gas inlet of the top part of the fourth falling film absorption tower (4) through a pipeline; The liquid outlet of the bottom part of the second falling film absorption tower (2) is connected with the liquid inlet of the top part of the second buffer tank (22) through a pipeline, the liquid outlet of the second buffer tank (22) is connected with the liquid inlet of the second falling film absorption tower bottom pump (10) through a pipeline, and the liquid outlet of the second falling film absorption tower bottom pump (10) is divided into two paths: one path is connected with the liquid inlet of the top part of the first buffer tank (21) through a pipeline, and the other path is connected with the liquid inlet of the side part of the second falling film absorption tower (2) through a pipeline; The liquid outlet of the fourth falling film absorption tower bottom pump (12) is connected with the liquid inlet of the top part of the second buffer tank (22) through a pipeline.

8. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 7, wherein The falling film absorption tower group comprises a third falling film absorption tower (3), the falling film tower bottom pump group comprises a third falling film absorption tower bottom pump (11), and the buffer tank group comprises a third buffer tank (23); The gas outlet of the side part of the first falling film absorption tower (1) is connected with the gas inlet of the top part of the second falling film absorption tower (2) through a pipeline, the gas outlet of the side part of the second falling film absorption tower (2) is connected with the gas inlet of the top part of the third falling film absorption tower (3) through a pipeline, and the gas outlet of the side part of the third falling film absorption tower (3) is connected with the gas inlet of the top part of the fourth falling film absorption tower (4) through a pipeline; The liquid outlet of the bottom part of the third falling film absorption tower (3) is connected with the liquid inlet of the top part of the third buffer tank (23) through a pipeline, the liquid outlet of the third buffer tank (23) is connected with the liquid inlet of the third falling film absorption tower bottom pump (11) through a pipeline, and the liquid outlet of the third falling film absorption tower bottom pump (11) is divided into two paths: one path is connected with the liquid inlet of the top part of the second buffer tank (22) through a pipeline, and the other path is connected with the liquid inlet of the side part of the third falling film absorption tower (3) through a pipeline; The liquid outlet of the fourth falling film absorption tower bottom pump (12) is connected with the liquid inlet of the top part of the third buffer tank (23) through a pipeline.

9. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 2, wherein The stirring kettle group comprises a stirring kettle one (17) and a stirring kettle two (18), compressed air is introduced into the bottom part of the stirring kettle one (17) and the stirring kettle two (18), the gas outlet of the top part of the stirring kettle one (17) and the gas outlet of the top part of the stirring kettle two (18) are both connected with the gas inlet of the side part of the first water spray tower (5) through a pipeline; the pipeline connected with the liquid inlet of the reaction kettle group from the liquid outlet of the first falling film absorption tower bottom pump (9) is divided into two paths: one pipeline is connected with the liquid inlet of the stirring kettle one (17), and the other pipeline is connected with the liquid inlet of the stirring kettle two (18).

10. The hydrogen chloride and sulfur dioxide off-gas recovery and reuse system of claim 1, wherein The temperature in each falling film absorption tower in the falling film absorption tower group is 30-50 DEG C; the temperature in each stirring kettle is 5-40 DEG C when the stirring kettle is bubbling; the temperature in the crystallization kettle is 5-15 DEG C; and the centrifugal temperature of the centrifugal machine (20) is 5-15 DEG C.

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