Brine method flue gas desulfurization device and process

Abstract

The invention is applicable to the technical field of flue gas desulfurization, and provides a brine-method flue gas desulfurization device and process, and the brine-method flue gas desulfurization process uses NaOH generated by causticization reaction as a desulfurization reactant; in the causticization reaction process, a desulfurizer NaOH is prepared, and magnesium ions in the brine are separated; in the desulfurization project, calcium ions in the brine are separated at the same time; the desulfurization device comprises a flue gas system, an SO2 absorption system, a desulfurizer preparation system, an aeration system, a precipitation concentration system and a process water circulation system, the flue gas system comprises a dust removal mechanism and an induced draft fan; the SO2 absorption system comprises an absorption tower; the desulfurizing agent preparation system comprises a quicklime powder bin, a weighing feeder and a lime slurry pulping tank. According to the invention, NaOH after causticization reaction in the brine is used for desulfurization, SO2 in the flue gas is removed, the brine is purified at the same time, the process does not have the problem of wastewater discharge, and a large amount of Na < + > in the brine can be recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas desulfurization, and in particular relates to a brine-based flue gas desulfurization device and process. Background Art

[0002] The traditional seawater desulfurization process uses alkaline substances in seawater - sodium base as a desulfurizer to absorb sulfur dioxide in flue gas. The desulfurized seawater contains Na2SO3, which is oxidized into Na2SO4 and then discharged back into the sea. Compared with other desulfurization processes, the seawater desulfurization process not only uses the sodium base in seawater as a desulfurizer, but also has no desulfurization by-products. It can be said to kill two birds with one stone, but seawater desulfurization is only suitable for coastal areas.

[0003] Various other desulfurization processes produce by-products, which are both expensive and laborious to dispose of, and are also one of the problems that are difficult to solve in the current desulfurization industry. The brine desulfurization process developed by our company solves this problem very well. In this regard, the present invention proposes a brine flue gas desulfurization device and process. Summary of the invention

[0004] The object of the present invention is to provide a brine flue gas desulfurization device and process to solve the problems in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a brine flue gas desulfurization device, the desulfurization device comprising a flue gas system, a SO2 absorption system, a desulfurization agent preparation system, an aeration system, a precipitation concentration system and a process water circulation system;

[0006] The flue gas system includes a dust removal mechanism and an induced draft fan; the SO2 absorption system includes an absorption tower; the desulfurizer preparation system includes a quicklime powder bin, a weighing feeder and a lime slurry preparation tank; the aeration system includes an aeration tank; the sedimentation and concentration system includes a sedimentation tank and a small concentration tank; the process water circulation system includes a process water tank.

[0007] Preferably, the dust removal mechanism is a bag filter and / or an electrostatic precipitator.

[0008] Preferably, the dust removal mechanism is connected to an induced draft fan via a pipeline, and the pipeline is connected to an absorption tower;

[0009] The absorption tower is connected to a process water tank through a pipeline, a process water inlet pipe is connected to the top of the process water tank, a demister flushing water pump is connected between the process water tank and the absorption tower, the process water tank is connected to a process water pump through a pipeline, the process water pump is provided with a cooling pipe, and cooling water is provided to the equipment through the cooling pipe;

[0010] The absorption tower is connected to a circulation pump, the input end and the output end of the circulation pump are both connected to the absorption tower through pipelines, and a brine discharge pump is provided at the bottom of the absorption tower, and the brine discharge pump is connected to the aeration tank through a pipeline;

[0011] A Roots blower is provided on one side of the aeration tank, and the Roots blower blows air into the aeration tank. A slurry discharge pump is connected to the outlet end of the aeration tank, and the slurry discharge pump is connected to the sedimentation tank through a pipeline.

[0012] The sedimentation tank is respectively connected to a screw pump and a discharge pump, the discharge pump is connected to a buffer tank through a pipeline, the buffer tank is connected to a first discharge pump through a pipeline, the first discharge pump is connected to an intermediate storage tank, the screw pump is connected to a small concentration tank through a pipeline, the bottom of the small concentration tank is connected to the first screw pump, and is connected to a deslag slurry tank through the first screw pump, the top of the small concentration tank is connected to a second filtrate tank through a pipeline, and a brine pump is connected between the second filtrate tank and the sedimentation tank;

[0013] The absorption tower is connected to a desulfurizer preparation system through a pipeline, and the desulfurizer preparation system includes a quicklime powder bin, a weighing feeder is connected to the bottom of the quicklime powder bin, an output end of the weighing feeder is connected to a lime slurry slurry making tank, the lime slurry slurry making tank is connected to a lime slurry discharge pump, the lime slurry discharge pump is connected to a mixing reaction tank through a pipeline, a second discharge pump is connected between the mixing reaction tank and the absorption tower, the mixing reaction tank is connected to a second screw pump through a pipeline, the second screw pump is connected to a slag slurry tank through a pipeline, the slag slurry tank is connected to a third screw pump through a pipeline, the third screw pump is connected to a vacuum filter through a pipeline, and the filtrate end outlet of the vacuum filter is connected to the first filtrate tank through a pipeline.

[0014] Preferably, the slurry tank is connected to a small-scale concentrator through a pipeline.

[0015] Preferably, the first filtrate tank is connected to the mixing reaction tank through a pipeline.

[0016] Preferably, a dosing device is connected to the top of the precipitation tank via a pipeline, a metering pump is provided between the dosing device and the precipitation tank, and the metering pump is connected to the mixing reaction tank via a pipeline.

[0017] Preferably, there are a plurality of mixing reaction tanks, which are arranged in parallel; and the precipitation and concentration system is a secondary precipitation system.

[0018] Preferably, a bag dust collector is provided on the top of the quicklime powder bin, an electric heater and a fluidizing fan are connected in series to the side wall of the quicklime powder bin, and a feeding valve is connected between the quicklime powder bin and the weighing feeder.

[0019] Preferably, the flue of the absorption tower is connected to the chimney through a pipeline, and an outlet baffle is provided between the chimney and the absorption tower.

[0020] The second aspect of the present invention provides a process for using the device described in the first aspect of the present invention for brine-based flue gas desulfurization, wherein the brine-based flue gas desulfurization process uses NaOH generated by a causticizing reaction as a desulfurization reactant; during the causticizing reaction, the desulfurization agent NaOH is prepared and magnesium ions in the brine are separated; during the desulfurization process, calcium ions in the brine are separated at the same time;

[0021] The specific steps are as follows:

[0022] S1, the flue gas system draws out the unpurified flue gas from the tail of the boiler and sends it to the dust removal mechanism. The flue gas after dust removal is sent to the absorption tower by the induced draft fan for desulfurization reaction. After purification meets the standard, it is discharged to the chimney through the flue to meet the discharge standard after the water mist is removed by the high-efficiency demister group. The reaction liquid after desulfurization will be pumped to the aeration tank by the brine discharge pump;

[0023] S2, connected from the water supply system of the construction party to the process water tank, to provide process water for the entire device; the transported lime powder is sent to the lime powder silo, and the feeding valve at the bottom of the lime powder silo is quantitatively sent to the lime slurry slurry tank through the weighing feeder, the lime powder is mixed with the process water in the lime slurry slurry tank, and after the slurry with a concentration of 10% is made, the lime slurry is discharged by the pump to the mixing reaction tank for causticization reaction with the old brine, and then sent to the precipitation tank after generating NaOH, the supernatant is sent to the first filtrate tank, and then pumped to the absorption tower to participate in the reaction, and the slurry is sent to the slurry tank;

[0024] S3, the brine circulating liquid that has completed desulfurization is pumped to the aeration tank by the brine discharge pump, and the Roots blower sends air into the aeration tank to react with the Na2SO3 in the brine that has completed desulfurization and the unreacted NaOH in the brine, so that the Na2SO3 is forced to be oxidized into Na2SO4, and the latter NaOH reacts with CO2 in the air to generate Na2CO3. At the same time, the Na2CO3 and CaSO4 in the brine undergo a replacement reaction and become CaCO3 and Na2SO4;

[0025] S4, the brine that has completed the aeration reaction is sent to the sedimentation tank for sedimentation and separation, so that the brine leaving the secondary sedimentation system and entering the buffer tank is pure brine.

[0026] The present invention has at least the following beneficial effects:

[0027] (1) The present invention provides a brine flue gas desulfurization device and process, which utilizes NaOH after causticization reaction in brine for desulfurization, removes SO2 from flue gas and purifies brine at the same time. This process does not have the problem of discharging wastewater. The Na in the brine is +Ability to be recycled in large quantities;

[0028] (2) The present invention provides a brine flue gas desulfurization device and process. After the desulfurized slurry is reacted in the absorption tower, it can be directly sent to the salt making workshop as a salt making raw material after aeration and precipitation. There is no need to perform subsequent treatment on the desulfurized product, and the process is relatively simple.

[0029] (3) The present invention provides a brine flue gas desulfurization device and process. In brine desulfurization, the circulating slurry is basically an aqueous solution of NaOH. During the circulation process, there will be no clogging of the water pump, pipeline, and equipment, which is convenient for equipment operation and maintenance and prolongs its service life.

[0030] (4) The present invention provides a brine-based flue gas desulfurization device and process. The sodium-based absorption liquid in the brine absorbs SO2 quickly, so a smaller liquid-to-gas ratio can be used to achieve a higher desulfurization efficiency and reduce operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall process of the present invention;

[0032] Figure 2 It is a schematic diagram of the process of the desulfurizing agent preparation system of the present invention;

[0033] Figure 3 It is a schematic diagram of the flow of the aeration system in the present invention;

[0034] Figure 4 It is a schematic diagram of the process of the precipitation system in the present invention.

[0035] In the accompanying drawings: 1. bag filter; 2. induced draft fan; 3. electrostatic precipitator; 4. absorption tower; 5. aeration tank; 6. process water tank; 7. mixing reaction tank; 8. weighing feeder; 9. lime slurry pulping tank; 10. quicklime powder silo; 11. dosing device; 12. buffer tank; 13. sedimentation tank; 14. small concentrating tank; 15. slurry tank; 16. second filtrate tank; 17. first filtrate tank; 18. vacuum filter. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Example

[0038] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 , the present invention provides a technical solution: a brine flue gas desulfurization device, including a flue gas system, a SO2 absorption system, a desulfurization agent preparation system, an aeration system, a precipitation concentration system and a process water circulation system;

[0039] The flue gas system includes a dust removal mechanism and an induced draft fan 2; the SO2 absorption system includes an absorption tower 4; the desulfurization agent preparation system includes a quicklime powder bin 10, a weighing feeder 8 and a lime slurry preparation tank 9; the aeration system includes an aeration tank 5; the sedimentation and concentration system includes a sedimentation tank 13 and then a small concentration tank 14; the process water circulation system includes a process water tank 6;

[0040] The dust removal mechanism is a bag dust collector 1 and / or an electrostatic dust collector 3;

[0041] The dust removal mechanism is connected to an induced draft fan 2 through a pipeline, and is connected to an absorption tower 4 through a pipeline;

[0042] The absorption tower 4 is connected to a process water tank 6 through a pipeline, a process water inlet pipe is connected to the top of the process water tank 6, a demister flushing water pump is connected between the process water tank 6 and the absorption tower 4, the process water tank 6 is connected to a process water pump through a pipeline, the process water pump is provided with a cooling pipe, and cooling water is provided to the equipment through the cooling pipe;

[0043] The absorption tower 4 is connected to a circulation pump, and the input end and the output end of the circulation pump are both connected to the absorption tower 4 through pipelines. A brine discharge pump is provided at the bottom of the absorption tower 4, and the brine discharge pump is connected to the aeration tank 5 through a pipeline;

[0044] A Roots blower is provided on one side of the aeration tank 5, and the Roots blower blows air into the aeration tank 5. A slurry discharge pump is connected to the outlet end of the aeration tank 5, and the slurry discharge pump is connected to the sedimentation tank 13 through a pipeline.

[0045] The settling tank 13 is respectively connected with a screw pump and a discharge pump, the discharge pump is connected with a buffer tank 12 through a pipeline, the buffer tank 12 is connected with a first discharge pump through a pipeline, the first discharge pump is connected with an intermediate storage tank, the screw pump is connected with a small concentration tank 14 through a pipeline, the bottom of the small concentration tank 14 is connected with the first screw pump, and is connected with a deslagging slurry tank through the first screw pump, the top of the small concentration tank 14 is connected with a second filtrate tank 16 through a pipeline, and a brine pump is connected between the second filtrate tank 16 and the settling tank 13;

[0046] The absorption tower 4 is connected to a desulfurizer preparation system through a pipeline, and the desulfurizer preparation system includes a quicklime powder bin 10, a weighing feeder 8 is connected to the bottom of the quicklime powder bin 10, the output end of the weighing feeder 8 is connected to a lime slurry pulping tank 9, the lime slurry pulping tank 9 is connected to a lime slurry discharge pump, the lime slurry discharge pump is connected to a mixing reaction tank 7 through a pipeline, a second discharge pump is connected between the mixing reaction tank 7 and the absorption tower 4, the mixing reaction tank 7 is connected to a second screw pump through a pipeline, the second screw pump is connected to a slag slurry tank 15 through a pipeline, the slag slurry tank 15 is connected to a third screw pump through a pipeline, the third screw pump is connected to a vacuum filter 18 through a pipeline, and the filtrate end outlet of the vacuum filter 18 is connected to the first filtrate tank 17 through a pipeline.

[0047] The slurry tank 15 is connected to the small concentration tank 14 through a pipeline; the first filtrate tank 17 is connected to the mixing reaction tank 7 through a pipeline; the top of the precipitation tank 13 is connected to the dosing device 11 through a pipeline, and a metering pump is connected between the dosing device 11 and the precipitation tank 13, and the metering pump is connected to the mixing reaction tank 7 through a pipeline; the slurry tank 15 is used to collect the magnesium hydroxide precipitated in the precipitation reaction tank, and then send it to the subsequent separation system for separation;

[0048] There are several mixing reaction tanks 7, and the several mixing reaction tanks 7 are arranged in parallel; the sedimentation and concentration system is a secondary sedimentation system; a bag dust collector is provided on the top of the quicklime powder bin 10, and an electric heater and a fluidizing fan are connected in series to the side wall of the quicklime powder bin 10, and a feeding valve is connected between the quicklime powder bin 10 and the weighing feeder 8; the flue of the absorption tower 4 is connected to the chimney 5 through a pipeline, and an outlet baffle is provided between the chimney 5 and the absorption tower 4.

[0049] The above device is used for the brine flue gas desulfurization process, which uses NaOH generated by causticization reaction as a desulfurization reagent; during the causticization reaction, the desulfurization agent NaOH is prepared and the magnesium ions in the brine are separated; in the desulfurization process, the calcium ions in the brine are separated at the same time;

[0050] The specific steps are as follows:

[0051] S1, the flue gas system draws out the unpurified flue gas from the tail of the boiler and sends it to the dust removal mechanism. The flue gas after dust removal is sent to the absorption tower 4 by the induced draft fan 2 for desulfurization reaction. After purification meets the standard, it is discharged to the chimney 5 through the flue to meet the discharge standard after the water mist is removed by the high-efficiency demister group. The reaction liquid after desulfurization is pumped to the aeration tank 5 by the brine discharge pump;

[0052] The brine flue gas desulfurization process has a similar reaction mechanism to other wet desulfurization processes. The main reaction is that SO2 in the flue gas first dissolves in the absorption liquid and then dissociates into H + and HSO3 ﹣ ;

[0053] (1) SO2(g)←→SO2(aq);

[0054] (2) SO2(aq)+H2O(l)←→H + +HSO3 ﹣ ←→2H + +SO3 2- ;

[0055] Formula (1) is a slow reaction and is one of the speed control processes.

[0056] Then H + With OH in solution ﹣ Neutralization reaction generates salt and water, which promotes the continuous absorption and dissolution of SO2. The specific reaction equation is as follows:

[0057] (3) 2NaOH+SO2→Na2SO3+H2O;

[0058] The reacted Na2SO3 and the unreacted NaOH solution are aerated to generate Na2SO4 and Na2CO3, and the unprecipitated CaSO4 in the circulating liquid is further precipitated. The main reaction formula is as follows:

[0059] (4) Na2SO3+1 / 2O2→Na2SO4;

[0060] (5) 2NaOH+CO2→Na2CO3;

[0061] (6)Na2CO3+CaSO4→Na2SO4+CaCO3↓.

[0062] S2, connect the water supply system of the construction party to the process water tank 6 to provide process water for the entire device; send the transported lime powder to the lime powder bin 10, and quantitatively send it to the lime slurry making tank 9 through the feed valve at the bottom of the lime powder bin 10 through the weighing feeder 8. The lime powder is mixed with process water in the lime slurry making tank 9 to make a slurry with a concentration of 10%. The lime slurry is discharged by a pump and sent to the mixing reaction tank 7 to react with the old brine for causticization. After generating NaOH, it is sent to the precipitation tank 13, and the supernatant is sent to the first filtrate tank 16, and then pumped to the absorption tower 4 to participate in the reaction, and the slurry is sent to the slurry tank 15;

[0063] The main reaction formula is as follows:

[0064] CaO+H2O→Ca(OH)2;

[0065] Ca(OH)2+Na2SO4→Ca2SO4↓+2NaOH;

[0066] Ca(OH)2+MgSO4→CaSO4↓+Mg(OH)↓.

[0067] S3, the brine circulating liquid that has completed desulfurization is pumped to the aeration tank 5 by the brine discharge pump, and the Roots blower sends air into the aeration tank 5 to react with the Na2SO3 in the brine that has completed desulfurization and the unreacted NaOH in the brine, so that the Na2SO3 is forced to be oxidized into Na2SO4, and the latter NaOH reacts with CO2 in the air to generate Na2CO3. At the same time, the Na2CO3 and CaSO4 in the brine undergo a replacement reaction to become CaCO3 and Na2SO4.

[0068] S4, the brine that has completed the aeration reaction is sent to the sedimentation tank 13 for sedimentation separation, so that the brine leaving the secondary sedimentation system and entering the buffer tank 12 is pure brine.

[0069] The desulfurization product of the brine method is Na2SO3. After oxidation precipitation, Na2SO4 and NaCl will be directly pumped to the intermediate storage tank in the salt making workshop.

[0070] Mg(OH)2 and most of the CaSO4 produced in the causticizing reaction will be precipitated and concentrated in the sedimentation tank and then sent to the fly ash yard for sale.

[0071] The remaining CaSO4 in the circulating liquid will react with Na2CO3 to generate CaCO3, which will then be precipitated and concentrated before being sent to the fly ash dump for sale.

[0072] The device includes five mixed reaction tanks 7, each of which is an independent system. After being filled, the slurry in each reaction tank undergoes causticization reaction and then completes precipitation. After precipitation, the slurry after the slag slurry is extracted is directly pumped to the bottom kettle of the absorption tower 4 to participate in the reaction, and the slag slurry is discharged to the slag slurry tank. The slag slurry tank 12 passes through a vacuum filter 18 to separate the brine and the residue. The brine is transferred to the mixed reaction tank 7 through the first filtrate pipe 17, and the residue is directly transferred to the coal ash yard.

[0073] The slurry in each mixing reaction tank 7 is fully stirred and mixed by the double-layer stirrer equipped therewith.

[0074] Each mixing reaction tank 7 is equipped with a double-layer top-entry agitator to ensure that the slurry at the bottom of the tower is fully contacted and reacted completely.

[0075] The mixer in each tank should be kept running at all times except when the liquid level in the tank reaches the "low" value, otherwise the slurry will settle.

[0076] A flow meter is installed on the outlet pipeline of each reaction tank to control the slurry delivery rate.

[0077] In the technical solution provided above, the causticizing reaction is carried out in a mixed reaction tank, that is, the preparation of the desulfurizer NaOH is completed in the mixed reaction tank, and the separation of magnesium ions in the brine is completed at the same time; in the desulfurization tower, desulfurization is completed, and the calcium ions in the brine are separated in the process (calcium carbonate is produced).

[0078] The working principle and use process of the present invention: After the present invention is installed, it works according to the above implementation method until all working steps are completed.

[0079] The basic principles, main features and advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

[0080] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A brine flue gas desulfurization device, characterized in that: The desulfurization device includes a flue gas system, a SO2 absorption system, a desulfurization agent preparation system, an aeration system, a precipitation concentration system and a process water circulation system; The flue gas system includes a dust removal mechanism and an induced draft fan (2); the SO2 absorption system includes an absorption tower (4); the desulfurization agent preparation system includes a quicklime powder bin (10), a weighing feeder (8) and a lime slurry preparation tank (9); the aeration system includes an aeration tank (5); the precipitation and concentration system includes a precipitation tank (13) and a small concentration tank (14); and the process water circulation system includes a process water tank (6).

2. A brine flue gas desulfurization device according to claim 1, characterized in that: The dust removal mechanism is a bag dust collector (1) and / or an electrostatic dust collector (3).

3. A brine flue gas desulfurization device according to claim 2, characterized in that: The dust removal mechanism is connected to an induced draft fan (2) via a pipeline, and the pipeline is connected to an absorption tower (4); The absorption tower (4) is connected to a process water tank (6) via a pipeline, a process water inlet pipe is connected to the top of the process water tank (6), a demister flushing water pump is connected between the process water tank (6) and the absorption tower (4), the process water tank (6) is connected to a process water pump via a pipeline, the process water pump is provided with a cooling pipe, and cooling water is provided to the equipment via the cooling pipe; The absorption tower (4) is connected to a circulation pump, the input end and the output end of the circulation pump are both connected to the absorption tower (4) through pipelines, and a brine discharge pump is provided at the bottom of the absorption tower (4), and the brine discharge pump is connected to the aeration tank (5) through a pipeline; A Roots blower is provided on one side of the aeration tank (5), and the Roots blower blows air into the aeration tank (5). A slurry discharge pump is connected to the outlet end of the aeration tank (5), and the slurry discharge pump is connected to the sedimentation tank (13) through a pipeline. The sedimentation tank (13) is respectively connected to a screw pump and a discharge pump, the discharge pump is connected to a buffer tank (12) via a pipeline, the buffer tank (12) is connected to a first discharge pump via a pipeline, the first discharge pump is connected to an intermediate storage tank, the screw pump is connected to a small concentration tank (14) via a pipeline, the bottom of the small concentration tank (14) is connected to the first screw pump, and is connected to a deslag slurry tank via the first screw pump, the top of the small concentration tank (14) is connected to a second filtrate tank (16) via a pipeline, and a brine pump is connected between the second filtrate tank (16) and the sedimentation tank (13); The absorption tower (4) is connected to a desulfurization agent preparation system through a pipeline. The desulfurization agent preparation system comprises a quicklime powder bin (10). The bottom of the quicklime powder bin (10) is connected to a weighing feeder (8). The output end of the weighing feeder (8) is connected to a lime slurry slurry making tank (9). The lime slurry slurry making tank (9) is connected to a lime slurry discharge pump. The lime slurry discharge pump is connected to a mixing reaction tank (7) through a pipeline. A second discharge pump is connected between the mixing reaction tank (7) and the absorption tower (4). The mixing reaction tank (7) is connected to a second screw pump through a pipeline. The second screw pump is connected to a slag slurry tank (15) through a pipeline. The slag slurry tank (15) is connected to a third screw pump through a pipeline. The third screw pump is connected to a vacuum filter (18) through a pipeline. The filtrate outlet of the vacuum filter (18) is connected to a first filtrate tank (17) through a pipeline.

4. A brine flue gas desulfurization device according to claim 3, characterized in that: The slurry tank (15) is connected to the small concentration tank (14) through a pipeline.

5. A brine flue gas desulfurization device according to claim 4, characterized in that: The first filtrate tank (17) is connected to the mixing reaction tank (7) through a pipeline.

6. A brine flue gas desulfurization device according to claim 5, characterized in that: The top of the precipitation tank (13) is connected to a dosing device (11) via a pipeline, a metering pump is provided between the dosing device (11) and the precipitation tank (13), and the metering pump is connected to a mixing reaction tank (7) via a pipeline.

7. A brine flue gas desulfurization device according to claim 6, characterized in that: The mixing reaction tanks (7) are provided in a plurality, and the plurality of mixing reaction tanks (7) are arranged in parallel; the precipitation and concentration system is a secondary precipitation system.

8. A brine flue gas desulfurization device according to claim 7, characterized in that: A bag dust collector is provided on the top of the quicklime powder bin (10), an electric heater and a fluidizing fan are connected in series on the side wall of the quicklime powder bin (10), and a feeding valve is connected between the quicklime powder bin (10) and the weighing feeder (8).

9. The brine flue gas desulfurization device according to claim 7, characterized in that: The flue of the absorption tower (4) is connected to the chimney (5) through a pipeline, and an outlet baffle is provided between the chimney (5) and the absorption tower (4).

10. The device according to any one of claims 1 to 9 is used in a process for brine flue gas desulfurization, characterized in that: The brine flue gas desulfurization process uses NaOH generated by causticization reaction as a desulfurization reactant; during the causticization reaction, the desulfurization agent NaOH is prepared and the magnesium ions in the brine are separated; during the desulfurization process, the calcium ions in the brine are separated at the same time; The specific steps are as follows: S1, the flue gas system draws out the unpurified flue gas from the tail of the boiler and sends it to the dust removal mechanism. The flue gas after dust removal is sent to the absorption tower (4) by the induced draft fan (2) for desulfurization reaction. After purification meets the standard, the water mist is removed by the high-efficiency demister group and then discharged to the chimney (5) through the flue to meet the discharge standard. The reaction liquid after desulfurization is sent to the aeration tank (5) by the brine discharge pump; S2, the water supply system of the construction party is connected to the process water tank (6) to provide process water for the entire device; the transported lime powder is sent to the lime powder bin (10), and the lime powder is quantitatively sent to the lime slurry making tank (9) through the feed valve at the bottom of the lime powder bin (10) through the weighing feeder (8); the lime powder is mixed with the process water in the lime slurry making tank (9) to make a slurry with a concentration of 10%, and then the lime slurry is discharged by the pump and sent to the mixing reaction tank (7) to react with the old brine for causticization, and then sent to the precipitation tank (13) after generating NaOH, and the supernatant is sent to the first filtrate tank (16), and then pumped to the absorption tower (4) to participate in the reaction, and the slurry is sent to the slurry tank (15); S3, the brine circulating liquid that has completed desulfurization is pumped to the aeration tank (5) by the brine discharge pump, and the Roots blower sends air into the aeration tank (5) to react with the Na2SO3 in the brine that has completed desulfurization and the unreacted NaOH in the brine, so that the Na2SO3 is forced to be oxidized into Na2SO4, and the latter NaOH reacts with CO2 in the air to generate Na2CO3. At the same time, the Na2CO3 and CaSO4 in the brine undergo a replacement reaction to become CaCO3 and Na2SO4; S4, the brine that has completed the aeration reaction is sent to the sedimentation tank (13) for sedimentation separation, so that the brine leaving the secondary sedimentation system and entering the buffer tank (12) is pure brine.

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