Treatment system for flue gas desulfurization based on alkali-making salty mud

Abstract

The utility model discloses a treatment system for flue gas desulfurization based on alkali-making salty mud, and belongs to the technical field of flue gas desulfurization based on alkali-making salty mud. The treatment system comprises a dissolving tank, a slurry box and a single-tower double-circulation desulfurizing tower which are connected in sequence, a flue gas outlet in the single-tower double-circulation desulfurizing tower is connected with a dust remover through a flue gas conveying pipe, and a purified flue gas discharge port is formed in the dust remover; a gypsum slurry discharge port on the single-tower double-circulation desulfurization tower is connected with a cyclone I through a gypsum slurry conveying pipe, a slurry outlet on the cyclone I is connected with a dehydration device through a gypsum slurry conveying pipe, a gypsum outlet on the dehydration device is connected with a gypsum recovery warehouse, and a filtrate outlet on the dehydration device is connected with a dissolving tank through a recovery pipe I. Orderliness, controllability and stability of flue gas desulfurization through salty mud treatment are achieved, the treatment efficiency and quality of SO2 in coal-fired flue gas are effectively improved, the utilization rate of salty mud is increased, and the purposes of energy conservation and emission reduction are effectively achieved.

Description

Technical Field

[0001] The utility model relates to a flue gas desulfurization processing system, in particular to a flue gas desulfurization processing system based on alkali salt mud, belonging to the technical field of flue gas desulfurization using alkali salt mud. Background Art

[0002] In the process of making alkali, saturated salt water is generally used as the main raw material, and caustic soda (sodium hydroxide) is prepared by electrolysis. The mud discharged in this process is called "salt mud", and its main components are CaCO3 (content about 90%), NaCl (content about 7%), Mg (OH) 2 (content about 2%), BaSO4 and mud sand. At present, most of the salt mud is directly dumped, piled or buried, etc., without being thoroughly treated, which harms the environment; some adopt a comprehensive utilization method, that is, using salt mud as raw material to prepare cement, artificial stone and other building materials. However, with the increasing requirements for energy conservation and emission reduction, restrictions on the building materials market and limited annual processing capacity, the harmless treatment and utilization of salt mud has become a huge challenge facing the development of this industry.

[0003] Since the main component of salt mud is CaCO3, its composition is the same as the desulfurizer involved in the wet desulfurization process of coal-fired flue gas - limestone powder. Therefore, salt mud is used as a desulfurizer in the wet desulfurization process of coal-fired flue gas (such as: CN1830525, CN101632896, CN103230739A, CN114873890A, etc.) to solve the problem of difficult salt mud solid waste treatment. Among them, after SO2 in coal-fired flue gas is absorbed by salt mud, the SO2 concentration decreases, and the chimney flue gas meets the emission requirements and is discharged into the atmosphere; gypsum mud is formed in the absorption tower, and then the gypsum mud is recycled and processed to obtain gypsum. The reaction formulas involved in the formation of gypsum mud include:

[0004] CaCO3+SO2+H2O →CaSO3·H2O +CO2;

[0005] CaSO3·H2O + SO2+ H2O→Ca(HSO3)2+H2O

[0006] Ca(HSO3)2+1 / 2O2+2H2O→CaSO4·2H2O+SO2+H2O;

[0007] CaSO3·H2O +1 / 2O2+2H2O→CaSO4·2H2O +H2O;

[0008] At present, there are several technical problems: the efficiency of using salt sludge to treat SO2 in coal-fired flue gas is low, SO2 cannot be absorbed well, resulting in subsequent emissions not meeting standards, or emissions can only meet standards after complex post-treatment processes; and the utilization rate of salt sludge is low.

[0009] Although the prior art CN103316577A discloses a "salt mud-purified brine flue gas desulfurization process", which combines the byproduct salt mud and purified brine in the flue gas desulfurization process to achieve the purpose of waste treatment and flue gas desulfurization; and CN103230739A discloses a "salt mud wet desulfurization method", which records that the solution in the liquid pool in the tower is transported to the upper spray pipe of the absorption tower through a circulating pump and sprayed into the tower through a nozzle, etc. However, none of them solves the problems of low flue gas desulfurization efficiency and poor treatment quality. Summary of the invention

[0010] In order to solve the problems of low efficiency and poor quality of salt mud in treating SO2 in coal-fired flue gas in the existing technology, and the ineffective utilization of salt mud, a flue gas desulfurization treatment system based on alkali salt mud is proposed. Among them, the orderliness, controllability and stability of salt mud treatment flue gas desulfurization are achieved through the specific arrangement of various equipment and pipelines; in particular, through the single tower double circulation (single tower double circulation desulfurization tower, including absorption tower and AFT tower), the treatment efficiency and quality of SO2 in coal-fired flue gas are improved, and at the same time, the utilization rate of salt mud is improved, and finally, the purpose of energy saving and emission reduction is effectively achieved.

[0011] In order to achieve the above technical objectives, the following technical solutions are proposed:

[0012] A treatment system for flue gas desulfurization based on alkali salt mud, comprising a dissolving tank for homogenizing salt mud, a slurry box for temporarily storing salt mud slurry, and a single-tower double-circulation desulfurization tower for adsorbing and demisting sulfur dioxide in coal-fired flue gas, the slurry box is arranged at the rear side of the dissolving tank station, and the discharge port on the dissolving tank is connected to the feed port on the slurry box through the salt mud conveying pipe I; the single-tower double-circulation desulfurization tower is arranged at the rear side of the slurry box station, and the discharge port on the slurry box is connected to the slurry inlet on the single-tower double-circulation desulfurization tower through the salt mud conveying pipe II;

[0013] The flue gas outlet on the single-tower double-circulation desulfurization tower is connected to a dust collector through a flue gas conveying pipe, and the dust collector is provided with a purified flue gas discharge port; the gypsum slurry discharge port on the single-tower double-circulation desulfurization tower is connected to a cyclone I through a gypsum slurry conveying pipe, the slurry outlet on the cyclone I is connected to a dehydration device through a gypsum slurry conveying pipe, the gypsum outlet on the dehydration device is connected to a gypsum recovery tank, and the filtrate outlet on the dehydration device is connected to a dissolution tank through a recovery pipe I.

[0014] Furthermore, a salt mud temporary storage tank is provided at the front side of the workstation of the dissolution tank, which collects and temporarily stores the salt mud, better connects with the subsequent dissolution tank, and ensures the stability, controllability and orderliness of the salt mud feeding program.

[0015] Furthermore, the dissolution tank is connected to a process water inlet pipe, and a stirring mechanism and a filter are provided in the dissolution tank. The process water inlet pipe provides dissolution water to the dissolution tank to dilute and dissolve the salt mud and control the density of the obtained salt mud (e.g., 1180-1200 kg / m 3 ); The setting of the stirring mechanism accelerates the dissolution of the salt mud and forms a uniform salt mud slurry, that is, the salt mud is homogenized; the filter screen filters the particles, lumps, insoluble matter, etc. in the salt mud, thereby ensuring the high efficiency and high quality of the subsequent flue gas desulfurization by the salt mud.

[0016] Furthermore, the slurry tank is connected to a limestone powder bin. When salt mud and other desulfurizers cannot be supplied in time, the limestone powder in the limestone powder bin is used to urgently prepare slurry to ensure the smooth progress of the desulfurization process.

[0017] Further, the single-tower double-circulation desulfurization tower includes an absorption tower and an AFT tower, the flue gas inlet is arranged at the lower part of the absorption tower, the absorption tower is provided with a reaction tank I at a position below the flue gas inlet, the reaction tank I is connected to the salt mud conveying pipe II through the slurry inlet, and the reaction tank I is connected to the air inlet pipe I; the absorption tower is provided with a primary spray device at a position above the flue gas inlet, a liquid accumulation tray is provided at a position above the primary spray device, a secondary spray device is provided at a position above the liquid accumulation tray, a demister is provided at a position above the secondary spray device, and the flue gas outlet is located at a position above the demister;

[0018] The reaction pool I is connected to the primary spray device through the circulation pipe I, and a continuous circulation passage I for recycling the salt mud spray flue gas is formed between the reaction pool I, the circulation pipe I, the primary spray device and the reaction pool I;

[0019] A reaction tank II is provided at the lower part of the AFT tower. The reaction tank II is connected with the salt mud conveying pipe II through the slurry inlet, and the reaction tank II is connected with the air inlet pipe II; the reaction tank II is connected with the secondary spraying device through the circulation pipe II, and the liquid accumulation tray is connected with the AFT tower through the salt mud recovery pipe. A continuous circulation passage II for recovering the salt mud spraying flue gas is formed among the reaction tank II, the circulation pipe II, the secondary spraying device, the liquid accumulation tray, the salt mud recovery pipe and the reaction tank II.

[0020] Furthermore, the reaction tank I is connected to the gypsum slurry delivery pipe through the gypsum slurry discharge port.

[0021] Furthermore, the reaction tank II is connected to a cyclone II, and the overflow port of the cyclone II is connected to the AFT tower through a recovery pipe II; the slurry outlet of the cyclone II is connected to the absorption tower.

[0022] Furthermore, the first-level spraying device includes a first-layer spraying pipe and a second-layer spraying pipe, the second-layer spraying pipe is arranged above the first-layer spraying pipe, the reaction pool I is connected to the first-layer spraying pipe through the circulation pipe I, and the reaction pool I is connected to the second-layer spraying pipe through the circulation pipe I. The salt slurry in the reaction pool I is circulated to improve the treatment efficiency and quality of SO2 in the coal-fired flue gas.

[0023] Furthermore, the secondary spray device includes a third-layer spray pipe, a fourth-layer spray pipe and a fifth-layer spray pipe. The fourth-layer spray pipe is arranged above the third-layer spray pipe, and the fifth-layer spray pipe is arranged above the fourth-layer spray pipe. The reaction pool II is connected to the third-layer spray pipe through the circulation pipe II, and the reaction pool II is connected to the fourth-layer spray pipe through the circulation pipe II. The reaction pool II is connected to the fifth-layer spray pipe through the circulation pipe II, and the salt sludge in the reaction pool II is circulated to improve the treatment efficiency and quality of SO2 in the coal-fired flue gas.

[0024] The relationships involved in this technical solution, such as "rear side of the workstation", "front side of the workstation", "top", "inside", "between", "lower part", "below" and "above", are defined according to the situations under actual usage conditions. They are conventional terms in this technical field and are also conventional terms used by technical personnel in this field in actual usage.

[0025] The beneficial technical effects brought about by adopting this technical solution are:

[0026] 1) The utility model realizes the orderliness, controllability and stability of flue gas desulfurization by salt mud treatment through the specific arrangement of various equipment and pipelines; in particular, through the single-tower double-circulation (single-tower double-circulation desulfurization tower, including absorption tower and AFT tower), the treatment efficiency and quality of SO2 in coal-fired flue gas are improved, and at the same time, the utilization rate of salt mud is improved, and finally, the purpose of energy saving and emission reduction is effectively achieved;

[0027] 2) The utility model realizes resource recycling through the coordinated processing of the alkali making industry and the wet desulfurization industry, and solves the problems in the industry, for example: saving the consumption of limestone powder and greatly reducing the desulfurization cost; solving the problem of handling the solid waste salt mud of the chlor-alkali plant, realizing resource recycling and turning waste into treasure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the flow chart of the utility model (I);

[0029] Figure 2 This is the flow chart of the utility model (II);

[0030] Figure 3 It is a schematic diagram of the working principle of the single-tower double-circulation desulfurization tower in the utility model;

[0031] In the figure, 1, dissolution tank, 2, slurry tank, 3, single tower double circulation desulfurization tower, 31, absorption tower, 311, flue gas outlet, 312, flue gas inlet, 313, reaction tank I, 314, primary spray device, 315, liquid accumulation tray, 316, secondary spray device, 317, demister, 32, AFT tower, 321, reaction tank II, 4, salt mud conveying pipe I, 5, salt mud conveying pipe II, 6, dust collector, 7, rotary Flow device I, 8, cyclone II, 9, wastewater delivery pipe, 10, gypsum slurry delivery pipe, 11, dehydration device, 12, gypsum recovery warehouse, 13, recovery pipe I, 14, salt mud temporary storage tank, 15, process water inlet pipe, 16, limestone powder warehouse, 17, air inlet pipe I, 18, circulation pipe I, 19, air inlet pipe II, 20, circulation pipe II, 21, salt mud recovery pipe, 22, recovery pipe II, 23, gypsum slurry delivery pipe. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] Example 1

[0034] This embodiment proposes: a treatment system for flue gas desulfurization based on alkali salt mud, such as Figure 1-2 As shown, it includes a dissolving tank 1 for homogenizing salt mud, a slurry tank 2 for temporarily storing salt mud, and a single-tower double-circulation desulfurization tower 3 for adsorbing and demisting sulfur dioxide in coal-fired flue gas. The slurry tank 2 is arranged at the rear side of the station of the dissolving tank 1, and the discharge port on the dissolving tank 1 is connected to the feed port on the slurry tank 2 through the salt mud conveying pipe Ⅰ4; the single-tower double-circulation desulfurization tower 3 is arranged at the rear side of the station of the slurry tank 2, and the discharge port on the slurry tank 2 is connected to the slurry inlet on the single-tower double-circulation desulfurization tower 3 through the salt mud conveying pipe Ⅱ5;

[0035] The flue gas outlet 311 on the single-tower double-circulation desulfurization tower 3 is connected to the dust collector 6 through the flue gas conveying pipe, and the dust collector 6 is provided with a purified flue gas discharge port; the gypsum slurry discharge port on the single-tower double-circulation desulfurization tower 3 is connected to the cyclone Ⅰ7 through the gypsum slurry conveying pipe 10, the slurry outlet on the cyclone Ⅰ7 is connected to the dehydration device 11 through the gypsum slurry conveying pipe 23, the gypsum outlet on the dehydration device 11 is connected to the gypsum recovery tank 12, and the filtrate outlet on the dehydration device 11 is connected to the dissolution tank 1 through the recovery pipe Ⅰ13; the overflow port on the cyclone Ⅰ7 is connected to the wastewater treatment station through the wastewater conveying pipe 9.

[0036] The work processes involved include:

[0037] 1. Put the salt mud sent from the chlor-alkali production line into the dissolution tank 1, and homogenize the salt mud, including dissolving and mixing. For example, the block salt mud is accelerated to dissolve under the action of the stirring mechanism. When the density of the salt mud reaches 1180-1200kg / m 3 When the salt slurry is filtered through the filter screen, it can be transported to the slurry tank 2 through the salt slurry pump;

[0038] 2. SO2 enters from the middle and lower part of the single-tower double-circulation desulfurization tower 3 along with the coal-fired flue gas, and spreads upwards. After being adsorbed and demisted by the single-tower double-circulation desulfurization tower 3, it is dedusted by the dust collector 6. Finally, it meets the national ultra-low emission requirements (dust ≤ 10mg / Nm³, sulfur dioxide ≤ 35mg / Nm³, nitrogen oxides ≤ 50mg / Nm³) under testing and is discharged into the atmosphere;

[0039] 3. The gypsum slurry discharged from the single-tower double-circulation desulfurization tower 3 is separated by cyclone Ⅰ7. The wastewater overflowing from cyclone Ⅰ7 enters the wastewater treatment station. The slurry discharged from cyclone Ⅰ7 is dehydrated by the dehydration device 11 to obtain gypsum (CaSO4•2H2O) and filtrate. The filtrate is directly returned to the dissolution tank 1. While achieving desulfurization, gypsum preparation and waste liquid recycling are realized, thereby achieving the purpose of energy conservation and emission reduction.

[0040] In this embodiment, according to actual needs, a concentration monitor, a pH detector, etc. are set on the corresponding equipment, and a delivery pump, a regulating valve, etc. are set on the corresponding pipeline.

[0041] Example 2

[0042] On the basis of Example 1, this example further limits the arrangement of the dissolution tank 1 to further illustrate the technical solution.

[0043] A salt mud temporary storage tank 14 is provided at the front side of the workstation of the dissolving tank 1, which collects and temporarily stores the salt mud, better connects with the subsequent dissolving tank 1, and ensures the stability, controllability and orderliness of the salt mud feeding program.

[0044] Example 3

[0045] On the basis of Examples 1-2, this example further defines the dissolution tank 1 to further illustrate the technical solution.

[0046] The dissolution tank 1 is connected to a process water inlet pipe 15, and a stirring mechanism and a filter screen are provided in the dissolution tank 1. There are two main sources of dissolution water for the dissolution tank 1, which dilute and dissolve the salt mud and control the density of the obtained salt mud (e.g., 1180-1200kg / m 3); one is the filtrate water discharged from the filtrate outlet of the dehydration device 11 through the recovery pipe I 13, and the other is the process water discharged from the process water inlet pipe 15; in the case of insufficient filtrate water, process water is used as a supplement to ensure the smoothness and stability of the subsequent supply of salt mud. The setting of the stirring mechanism accelerates the dissolution of salt mud and forms a uniform salt mud, that is, the salt mud is homogenized; the filter screen filters the particles, lumps, insolubles, etc. in the salt mud, thereby ensuring the high efficiency and high quality of the subsequent flue gas desulfurization of the salt mud.

[0047] Example 4

[0048] On the basis of Examples 1-3, this example further defines the slurry box 2 to further illustrate the technical solution.

[0049] The slurry tank 2 is connected to a limestone powder bin 16. When salt mud and other desulfurizing agents cannot be supplied in time, the limestone powder in the limestone powder bin 16 is used to urgently prepare slurry to ensure the smooth progress of the desulfurization process.

[0050] In addition, according to actual needs, other desulfurizing agents (such as white mud from a paper mill) can be added to the dissolution tank 1.

[0051] Example 5

[0052] On the basis of Examples 1-5, this example further defines and illustrates the single-tower dual-circulation desulfurization tower 3 to further illustrate the technical solution.

[0053] like Figure 3 As shown, the single-tower double-circulation desulfurization tower 3 includes an absorption tower 31 and an AFT tower 32, a flue gas inlet 312 is arranged at the lower part of the absorption tower 31, and the absorption tower 31 is provided with a reaction tank I 313 at a position below the flue gas inlet 312, the reaction tank I 313 is connected with the salt mud conveying pipe II 5 through the slurry inlet, and the reaction tank I 313 is connected with the air inlet pipe I 17; the absorption tower 31 is provided with a primary spray device 314 at a position above the flue gas inlet 312, a liquid accumulation tray 315 is provided at a position above the primary spray device 314, a secondary spray device 316 is provided at a position above the liquid accumulation tray 315, a demister 317 is provided at a position above the secondary spray device 316, and the flue gas outlet 311 is located at a position above the demister 317;

[0054] The reaction pool I 313 is connected to the primary spray device 314 through the circulation pipe I 18, and a continuous circulation passage I for salt mud spraying flue gas recycle is formed between the reaction pool I 313, the circulation pipe I 18, the primary spray device 314 and the reaction pool I 313;

[0055] A reaction tank II 321 is provided at the lower part of the AFT tower 32. The reaction tank II 321 is connected to the salt mud conveying pipe II 5 through the slurry inlet, and the reaction tank II 321 is connected to the air inlet pipe II 19; the reaction tank II 321 is connected to the secondary spray device 316 through the circulation pipe II 20, and the liquid accumulation tray 315 is connected to the AFT tower 32 through the salt mud recovery pipe 21. A continuous circulation passage II for recovering the salt mud spraying flue gas is formed among the reaction tank II 321, the circulation pipe II 20, the secondary spray device 316, the liquid accumulation tray 315, the salt mud recovery pipe 21 and the reaction tank II 321.

[0056] Among them, the reaction tank I 313 is connected to the gypsum slurry conveying pipe 10 through the gypsum slurry discharge port. Alternatively, since the alkali salt mud contains NaCl, the chloride ion concentration in the entire coal-fired flue gas wet desulfurization system increases, which not only affects the flue gas desulfurization efficiency and quality, but also has a corrosive effect on the desulfurization equipment. For this reason, a wastewater treatment system can be added, that is, the unreacted salt mud discharged from the reaction tank I 313 is separated by a cyclone, and the formed chloride ion-rich wastewater is post-treated, and the formed slurry is returned to the reaction tank I 313, and the cycle is repeated until the chloride ion concentration in the slurry discharged from the gypsum slurry discharge port on the reaction tank I 313 meets the requirements of gypsum production (easy to dehydrate, etc.).

[0057] In addition, the reaction tank II 321 is connected to a cyclone II 8 , the overflow port of the cyclone II 8 is connected to the AFT tower 32 through a recovery pipe II 22 , and the slurry outlet of the cyclone II 8 is connected to the absorption tower 31 .

[0058] The primary spray device 314 includes a first layer spray pipe and a second layer spray pipe, the second layer spray pipe is arranged above the first layer spray pipe, the reaction pool I 313 is connected to the first layer spray pipe through the circulation pipe I 18, and the reaction pool I 313 is connected to the second layer spray pipe through the circulation pipe I 18. The salt slurry in the reaction pool I 313 is circulated to improve the treatment efficiency and quality of SO2 in the coal-fired flue gas.

[0059] For the secondary spray device 316: it includes a third-layer spray pipe, a fourth-layer spray pipe and a fifth-layer spray pipe. The fourth-layer spray pipe is arranged above the third-layer spray pipe, and the fifth-layer spray pipe is arranged above the fourth-layer spray pipe. The reaction pool II 321 is connected with the third-layer spray pipe through the circulation pipe II 20, and the reaction pool II 321 is connected with the fourth-layer spray pipe through the circulation pipe II 20. The reaction pool II 321 is connected with the fifth-layer spray pipe through the circulation pipe II 20, and the salt sludge in the reaction pool II 321 is circulated to improve the treatment efficiency and quality of SO2 in the coal-fired flue gas.

[0060] The control processes involved include:

[0061] 1. The salt slurry is transported to the corresponding spray layer, and under the action of the spray device nozzle, it forms slurry droplets, flows downward, absorbs SO2 in the flue gas, and returns to the corresponding reaction tank respectively;

[0062] 2. In order to ensure the stability of the pH value in reaction tank I 313 and reaction tank II 321, salt sludge is intermittently added to the absorption tower 31 (control the pH value at 4-5) and the AFT tower 32 (control the pH value at 5-6) through the salt sludge delivery pump. At the same time, a small amount of air (oxygen) is added to the AFT tower 32 through the corresponding air inlet pipe to form Ca(HSO3)2 and CaSO3•H2O in the reaction tank of AFT tower 32; then, it is transported to cyclone II 8 for separation through the cyclone pump of AFT tower 32, and the separated slurry including Ca(HSO3)2 and CaSO3•H2O returns to reaction tank I 313 to continue to participate in the desulfurization reaction. In reaction tank Ⅰ313, a large amount of air (oxygen) is introduced into reaction tank Ⅰ313 through air inlet pipe Ⅰ17, so that Ca(HSO3)2 and CaSO3•H2O react with O2 in reaction tank Ⅰ313 to generate gypsum (CaSO4•2H2O), which is then discharged from gypsum slurry conveying pipe 10, and gypsum is recovered through cyclone and dehydration, thereby ensuring the utilization rate of salt mud.

Claims

1. A flue gas desulfurization treatment system based on alkali salt sludge, characterized in that: The invention comprises a dissolving tank (1) for homogenizing salt mud, a slurry tank (2) for temporarily storing salt mud, and a single-tower double-circulation desulfurization tower (3) for adsorbing and demisting sulfur dioxide in coal-fired flue gas, wherein the slurry tank (2) is arranged at the rear side of the working station of the dissolving tank (1), and the discharge port on the dissolving tank (1) is connected to the feed port on the slurry tank (2) through a salt mud conveying pipe I (4); the single-tower double-circulation desulfurization tower (3) is arranged at the rear side of the working station of the slurry tank (2), and the discharge port on the slurry tank (2) is connected to the slurry inlet on the single-tower double-circulation desulfurization tower (3) through a salt mud conveying pipe II (5); The flue gas outlet (311) on the single-tower double-circulation desulfurization tower (3) is connected to a dust collector (6) via a flue gas conveying pipe, and the dust collector (6) is provided with a purified flue gas discharge port; the gypsum slurry discharge port on the single-tower double-circulation desulfurization tower (3) is connected to a cyclone I (7) via a gypsum slurry conveying pipe (10), the slurry outlet on the cyclone I (7) is connected to a dehydration device (11) via a gypsum slurry conveying pipe (23), the gypsum outlet on the dehydration device (11) is connected to a gypsum recovery tank (12), and the filtrate outlet on the dehydration device (11) is connected to a dissolution tank (1) via a recovery pipe I (13).

2. The flue gas desulfurization treatment system based on alkali salt mud according to claim 1 is characterized in that: A salt mud temporary storage tank (14) is provided at the front side of the workstation of the dissolution tank (1).

3. The flue gas desulfurization treatment system based on alkali salt mud according to claim 1 is characterized in that: The dissolution tank (1) is connected to a process water inlet pipe (15), and a stirring mechanism and a filter are provided in the dissolution tank (1).

4. The flue gas desulfurization treatment system based on alkali salt mud according to claim 1 is characterized in that: The slurry tank (2) is connected to a limestone powder bin (16).

5. The flue gas desulfurization treatment system based on alkali salt mud according to any one of claims 1 to 4, characterized in that: The single-tower dual-circulation desulfurization tower (3) comprises an absorption tower (31) and an AFT tower (32); a flue gas inlet (312) is arranged at the lower part of the absorption tower (31); a reaction tank I (313) is arranged at a position below the flue gas inlet (312) of the absorption tower (31); the reaction tank I (313) is connected to the salt slurry conveying pipe II (5) through a slurry inlet; the reaction tank I (313) is connected to an air inlet pipe I (17); a primary spray device (314) is arranged at a position above the flue gas inlet (312) of the absorption tower (31); a liquid accumulation tray (315) is arranged at a position above the primary spray device (314); a secondary spray device (316) is arranged at a position above the liquid accumulation tray (315); a demister (317) is arranged at a position above the secondary spray device (316); and a flue gas outlet (311) is located at a position above the demister (317); The reaction pool I (313) is connected to the primary spray device (314) through the circulation pipe I (18), and a continuous circulation passage I for recycling salt mud spray flue gas is formed between the reaction pool I (313), the circulation pipe I (18), the primary spray device (314) and the reaction pool I (313); A reaction tank II (321) is provided at the lower part of the AFT tower (32). The reaction tank II (321) is connected to the salt slurry conveying pipe II (5) through a slurry inlet, and the reaction tank II (321) is connected to an air inlet pipe II (19). The reaction tank II (321) is connected to the secondary spraying device (316) through a circulation pipe II (20), and the liquid accumulation tray (315) is connected to the AFT tower (32) through a salt slurry recovery pipe (21). A continuous circulation passage II for recovering the salt slurry spraying flue gas is formed between the reaction tank II (321), the circulation pipe II (20), the secondary spraying device (316), the liquid accumulation tray (315), the salt slurry recovery pipe (21) and the reaction tank II (321).

6. The flue gas desulfurization treatment system based on alkali salt mud according to claim 5 is characterized in that: The reaction tank I (313) is connected to the gypsum slurry conveying pipe (10) through the gypsum slurry discharge port.

7. The flue gas desulfurization treatment system based on alkali salt mud according to claim 6 is characterized in that: The reaction tank II (321) is connected to a cyclone II (8), the overflow port of the cyclone II (8) is connected to the AFT tower (32) through a recovery pipe II (22), and the slurry outlet of the cyclone II (8) is connected to the absorption tower (31).

8. The flue gas desulfurization treatment system based on alkali salt mud according to claim 5 is characterized in that: The primary spray device (314) comprises a first-layer spray pipe and a second-layer spray pipe, wherein the second-layer spray pipe is arranged above the first-layer spray pipe, the reaction pool I (313) is connected to the first-layer spray pipe via a circulation pipe I (18), and the reaction pool I (313) is connected to the second-layer spray pipe via a circulation pipe I (18).

9. The flue gas desulfurization treatment system based on alkali salt mud according to claim 5 is characterized in that: The secondary spray device (316) comprises a third-layer spray pipe, a fourth-layer spray pipe and a fifth-layer spray pipe, wherein the fourth-layer spray pipe is arranged above the third-layer spray pipe, and the fifth-layer spray pipe is arranged above the fourth-layer spray pipe. The reaction pool II (321) is connected to the third-layer spray pipe via the circulation pipe II (20), the reaction pool II (321) is connected to the fourth-layer spray pipe via the circulation pipe II (20), and the reaction pool II (321) is connected to the fifth-layer spray pipe via the circulation pipe II (20).

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