A flue gas defluorination, desulfurization and dust removal purification system and process

Abstract

The present invention relates to the technical field of electrolytic aluminum flue gas treatment, and in particular to a flue gas defluorination, desulfurization and dust removal purification system and process, wherein the flue gas defluorination, desulfurization and dust removal purification system comprises a defluorination and dust removal section, a desulfurization and dust removal section, an induced draft fan and a chimney connected in sequence, wherein the defluorination and dust removal section comprises a first bottom flue, a first separator, a first upper flue, a first dust removal box, a first distributor, a second distributor, and a first return box, wherein the desulfurization and dust removal section comprises a second bottom flue, a second separator, a second upper flue, a second dust removal box, a third distributor, a fourth distributor, and a second return box; and the flue gas defluorination, desulfurization and dust removal purification process comprises a defluorination step in which two defluorination reactions occur and a desulfurization step in which two desulfurization reactions occur. The system of the present invention occupies a small area, has a low construction cost, reduces the resistance to operation, and has a good purification effect.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic aluminum fume treatment, and in particular to a fume defluorination, desulfurization, dust removal and purification system and process. Background Art

[0002] A large amount of flue gas is generated during the production of electrolytic aluminum. The amount of flue gas produced per ton of aluminum electrolysis is 70,000 Nm 3 The harmful substances in the flue gas are mainly fluorine-containing gases, fluorine-containing dust and SO 2 According to the test data, the concentration of harmful substances in electrolytic flue gas is about 450mg / Nm 3 , fluorine-containing dust is about 750mg / Nm 3 , SO 2 About 250mg / Nm 3 In order to improve resource utilization and reduce environmental pollution, enterprises need to treat electrolytic flue gas during production.

[0003] Since the fluoride in the flue gas needs to be removed and recycled to the electrolytic cell, the current electrolytic aluminum enterprises first build a purification system to remove and recycle the fluoride in the flue gas, and then build a desulfurization system at the outlet of the purification system to remove SO 2 . Aluminum electrolytic enterprises generally adopt the limestone-gypsum wet desulfurization technology of the power industry and the semi-dry desulfurization technology using slaked lime as a desulfurizer. Regardless of which of the above technologies is adopted, the desulfurization system is simply connected in series with the purification system, and a large desulfurization tower and many auxiliary equipment need to be built, resulting in complex overall purification system processes, large floor space, and high construction costs. Secondly, the current operating resistance of the electrolytic aluminum purification system is about 2500Pa, while the above-mentioned desulfurization technology introduced from the power and steel industries has a system resistance of up to 3000Pa-4000Pa, and the comprehensive resistance of the entire flue gas treatment system is as high as 6000Pa or more. Therefore, the current construction cost and system resistance of the flue gas purification system are too high, and it is necessary to develop new systems and processes for treating flue gas. Summary of the invention

[0004] The present invention provides a flue gas defluorination, desulfurization and dust removal purification system to solve the problems of large system resistance and high construction cost of the existing flue gas treatment system. It also provides a flue gas defluorination, desulfurization and dust removal purification process.

[0005] A flue gas defluorination, desulfurization and dust removal purification system of the present invention adopts the following technical scheme:

[0006] A flue gas defluorination, desulfurization and dust removal purification system, comprising a defluorination and dust removal section, a desulfurization and dust removal section, an induced draft fan and a chimney connected in sequence;

[0007] The defluorination and dust removal section includes a first bottom flue, a first separator, a first upper flue and a first dust removal box connected in sequence, a first distributor for adding fluorine-containing defluorination material is provided in the first bottom flue, a second distributor for adding fresh defluorination material is provided in the first upper flue, and also includes a first return box for collecting and distributing fluorine-containing defluorination material, the discharge ports of the first separator and the first dust removal box for discharging fluorine-containing defluorination material are respectively connected to the feed port of the first return box, the first return box is provided with two discharge ports and one of them is connected to the first distributor so as to convey the fluorine-containing defluorination material for recycling thereto;

[0008] The desulfurization and dust removal section includes a second bottom flue, a second separator, a second upper flue and a second dust removal box connected in sequence, a third distributor for adding sulfur-containing desulfurization material is provided in the second bottom flue, a fourth distributor for adding fresh desulfurization material is provided in the second upper flue, and also includes a second return box for collecting and distributing fluorine-containing defluorination material, the discharge ports of the second separator and the second dust removal box are respectively connected to the feed port of the second return box, the second return box is provided with two discharge ports and one of them is connected to the third distributor so as to convey the sulfur-containing desulfurization material for recycling thereto, the second return box is provided with a spiral stirrer for stirring the collected sulfur-containing desulfurization material and a nozzle for spraying process water to humidify the collected sulfur-containing desulfurization material;

[0009] The second bottom flue of the desulfurization and dust removal section is connected to the first dust removal box pipe of the defluorination and dust removal section, and the air inlet and air outlet of the induced draft fan are respectively connected to the second dust removal box and the chimney pipe.

[0010] A gas heat exchanger and a fluidizing fan for extracting hot air from the gas heat exchanger are provided on the pipeline between the induced draft fan and the second dust removal box. The air outlet of the fluidizing fan is respectively connected to the bottom of the first dust removal box, the bottom of the second dust removal box, the bottom of the first return box and the bottom pipeline of the second return box to supply fluidizing air.

[0011] A first valve is provided on each of the two discharge ports of the first return box, and the first valve connected to the first distributor is adjusted to control the circulation amount of the fluorine-containing defluorination material; a second valve is provided on each of the two discharge ports of the second return box, and the second valve connected to the third distributor is adjusted to control the circulation amount of the sulfur-containing desulfurization material.

[0012] Material blocking plates for dispersing the material so as to facilitate it to follow the flow of smoke are arranged below the first distributor, the second distributor, the third distributor and the fourth distributor.

[0013] The first bottom flue, the first upper flue, the second bottom flue and the second upper flue are all provided with guide plates for guiding the flow of smoke to reduce vortex and lower resistance.

[0014] The first dust removal box and the second dust removal box are respectively any one of an electrostatic precipitator, a bag dust collector and an electric bag composite dust collector.

[0015] The first separator and the second separator are both cyclone separators.

[0016] A flue gas defluorination, desulfurization and dust removal purification process of the present invention comprises the following steps:

[0017] Step one, passing the flue gas into the first bottom flue, and then carrying out the first defluorination reaction with the fluorine-carrying defluorination material added into the first bottom flue by the first distributor, the flue gas after the reaction and the solid-gas mixture of the fluorine-carrying defluorination material enter the first separator for separation, the flue gas after separation enters the first upper flue, the fluorine-carrying defluorination material enters the first return box, the second distributor adds fresh defluorination material into the first upper flue, the flue gas and the fresh defluorination material carry out the second defluorination reaction, the fresh defluorination material reacts to generate fluorine-carrying defluorination material and enters the first dust removal box together with the flue gas for filtration, the filtered flue gas enters the next step, the fluorine-carrying defluorination material enters the first return box, one discharge port of the first return box conveys the fluorine-carrying defluorination material for recycling to the first distributor, and the other discharge port is used to discharge the fluorine-carrying defluorination material;

[0018] Step 2: The flue gas delivered from the previous step is passed into the second bottom flue, and then the third distributor adds the sulfur-carrying desulfurization material into the second bottom flue for the first desulfurization reaction. The flue gas and the solid-gas mixture of the sulfur-carrying desulfurization material after the reaction enter the second separator for separation. After separation, the flue gas enters the second upper flue, and the sulfur-carrying desulfurization material enters the second return box. The fourth distributor adds fresh desulfurization material into the second upper flue, and the flue gas and the fresh desulfurization material undergo a second desulfurization reaction. The fresh desulfurization material reacts Fluorine-containing desulfurization material should be generated and enter the second dust removal box for filtration together with the flue gas. The filtered flue gas enters the next step, and the sulfur-containing desulfurization material enters the second return box. One discharge port of the second return box conveys the sulfur-containing desulfurization material for recycling to the third distributor, and the other discharge port is used to discharge the sulfur-containing desulfurization material. When the sulfur-containing desulfurization material enters the second return box, the spiral stirrer is started to stir the sulfur-containing desulfurization material, and the nozzle is allowed to spray process water to humidify the sulfur-containing desulfurization material to ensure the fluidity of the sulfur-containing desulfurization material.

[0019] Step three, the treated flue gas delivered from the previous step is sent to the induced draft fan through a pipeline and is drawn into the chimney by the induced draft fan and then discharged.

[0020] Fluidizing air for promoting the flow of fluorine-containing defluorination materials is introduced into the bottom of the first return box and the bottom of the first dust removal box. Fluidizing air for promoting the flow of sulfur-containing desulfurization materials is also introduced into the bottom of the second return box and the bottom of the second dust removal box. The fluidizing air is provided by a fluidizing fan.

[0021] After being discharged from the second dust removal box, the flue gas exchanges heat with the gas heat exchanger, the fluidizing fan extracts hot air from the gas heat exchanger, and the flue gas after heat exchange is drawn into the chimney by the induced draft fan.

[0022] The beneficial effects of the present invention are: 1. The present invention does not require a traditional desulfurization tower, so the system occupies a small area, has a low construction cost, and the resistance of system operation is reduced. The total resistance of the entire system is within 3500Pa, which is particularly suitable for treating aluminum electrolytic cell flue gas with low sulfur dioxide concentration and large flue gas volume or the purification of similar flue gas.

[0023] 2. The defluorination and dust removal section and the desulfurization and dust removal section of the present invention both adopt a two-stage reaction process, that is, the high-concentration flue gas first undergoes an adsorption reaction with the recycled material (fluorine-carrying defluorination material or sulfur-carrying desulfurization material), and the low-concentration flue gas after the reaction then reacts with the newly added material (defluorination material or desulfurization material). The two-stage reaction can achieve a better purification effect.

[0024] 3. The materials of the present invention (fluorine-carrying defluorination material, sulfur-carrying desulfurization material, defluorination material, desulfurization material) are all added from top to bottom, and the flue gas contacts and mixes with the materials from bottom to top, and the reverse reaction makes the reaction proceed more fully.

[0025] 4. The defluorination dust removal section and the desulfurization dust removal section of the present invention are respectively provided with a first separator and a second separator, which can separate the material and the flue gas to a certain extent (separation efficiency is about 70%), thereby reducing the operating load of the corresponding first dust removal box and the second dust removal box, and reducing the system construction cost and operation cost.

[0026] 5. In the defluorination and dust removal section and the desulfurization and dust removal section of the present invention, the first return box and the second return box can both provide materials for recycling, which can increase the number of times the material re-participates in the reaction, increase the material concentration, enable the material to fully react with the flue gas, and improve the purification efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1It is a structural schematic diagram of a specific embodiment of a flue gas defluorination, desulfurization and dust removal purification system of the present invention;

[0029] In the figure: 1, first bottom flue; 2, first separator; 3, first upper flue; 4, material blocking plate; 5, first pneumatic chute; 6, second distributor; 7, first dust removal box; 8, first ash hopper; 9, first return box; 10, first regulating valve; 11, first distributor; 12, first discharge valve; 13, first pipeline; 14, second bottom flue; 15, second separator; 16, second upper flue; 17, second pneumatic chute ; 18. Fourth distributor; 19. Second dust removal box; 20. Second ash hopper; 21. Nozzle; 22. Second return box; 23. Spiral agitator; 24. Second regulating valve; 25. Third distributor; 26. Second discharge valve; 27. Second pipeline; 28. Fluidizing fan; 29. ​​Gas heat exchanger; 30. induced draft fan; 31. Chimney; 32. Guide plate; 33. Fluorine-carrying defluorination material conveying chute; 34. Sulfur-carrying desulfurization material conveying chute. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] An embodiment of a flue gas defluorination, desulfurization and dust removal purification system of the present invention is as follows Figure 1 As shown, a flue gas defluorination, desulfurization and dust removal purification system includes a defluorination and dust removal section, a desulfurization and dust removal section, an induced draft fan 30 and a chimney 31 connected in sequence;

[0032] The defluorination and dust removal section includes a first bottom flue 1, a first separator 2, a first upper flue 3 and a first dust removal box 7 which are connected in sequence. A first distributor 11 for adding fluorine-containing defluorination material is provided in the first bottom flue 1, a second distributor 6 for adding fresh defluorination material is provided in the first upper flue 3, and also includes a first return box 9 for collecting and distributing fluorine-containing defluorination material. The discharge ports of the first separator 2 and the first dust removal box 7 for discharging the fluorine-containing defluorination material are respectively connected to the feed port of the first return box 9. The first return box 9 is provided with two discharge ports, one of which is connected to the first distributor 11 so as to convey the fluorine-containing defluorination material for recycling thereto.

[0033] The desulfurization and dust removal section includes a second bottom flue 14, a second separator 15, a second upper flue 16 and a second dust removal box 19 which are connected in sequence. A third distributor 25 for adding sulfur-carrying desulfurization material is provided in the second bottom flue 14, and a fourth distributor 18 for adding fresh desulfurization material is provided in the second upper flue 16. It also includes a second return box 22 for collecting and distributing fluorine-carrying defluorination material. The discharge ports of the second separator 15 and the second dust removal box 19 are respectively connected to the feed port of the second return box 22. The second return box 22 has two discharge ports, one of which is connected to the third distributor 25 so as to convey the sulfur-carrying desulfurization material for recycling. The second return box 22 is provided with a spiral stirrer 23 for stirring the collected sulfur-carrying desulfurization material and a nozzle 21 for spraying process water to humidify the collected sulfur-carrying desulfurization material.

[0034] The second bottom flue 14 of the desulfurization and dust removal section is connected to the first dust removal box 7 of the defluorination and dust removal section through the first pipe 13, the air inlet of the induced draft fan 30 is connected to the second dust removal box 19 through the second pipe 27, and the air outlet of the induced draft fan 30 is connected to the chimney 31 pipe.

[0035] In this embodiment, a gas heat exchanger 29 for exchanging heat with flue gas and a fluidizing fan 28 for extracting heated hot air from the gas heat exchanger 29 are provided on the pipeline between the induced draft fan 30 and the second dust removal box 19, i.e., the second pipeline 27. The gas heat exchanger 29 is an air-to-air heat exchanger. The air outlet of the fluidizing fan 28 is respectively connected to the bottom pipelines of the first dust removal box 7, the bottom of the second dust removal box 19, the bottom of the first return box 9 and the bottom pipeline of the second return box 22 to supply hot fluidizing air. The fluidizing air is used to fluidize the material to facilitate the transportation of the material; or the air outlet of the fluidizing fan 28 can be connected to the cold air inlet of the gas heat exchanger 29, and the hot air outlet of the gas heat exchanger 29 can be connected to the above-mentioned device requiring fluidizing air. The fluidizing air generated by the fluidizing fan 28 is heated by the gas heat exchanger 29 and then sent to the corresponding device through a preset air supply pipeline, thereby preventing condensation from occurring in the system after the cold air enters the system and affecting the fluidity of the material.

[0036] In other embodiments, fluidizing fans may be provided separately, and each fluidizing fan may be provided with a fluidizing air heating device separately; or other material conveying methods may be adopted.

[0037] In this embodiment, a first valve is provided on each of the two discharge ports of the first return box 9, namely, a first regulating valve 10 and a first discharge valve 12, wherein the first regulating valve 10 is correspondingly connected to the first distributor 11, and the first discharge valve 12 is connected to the fluorine-containing defluorination material conveying chute 33 and is used to discharge the fluorine-containing defluorination material. The first regulating valve 10 is adjusted to control the circulation amount of the fluorine-containing defluorination material; a second valve is provided on each of the two discharge ports of the second return box 22, namely, a second regulating valve 24 and a second discharge valve 26, wherein the second regulating valve 24 is correspondingly connected to the third distributor 25, and the second discharge valve 26 is connected to the sulfur-containing desulfurization material conveying chute 34 and is used to discharge the sulfur-containing desulfurization material. The second regulating valve 24 is adjusted to control the circulation amount of the sulfur-containing desulfurization material.

[0038] In other embodiments, the first valve and the second valve may not be provided, and the circulation amount of the corresponding material may be adjusted by adjusting the size of the discharge ports of the first return box and the second return box and the flow rate of the fluidizing air.

[0039] In this embodiment, a material blocking plate 4 for dispersing the material so that it can follow the flow of smoke is provided below the first distributor 11, the second distributor 6, the third distributor 25 and the fourth distributor 18. The first distributor 11, the second distributor 6, the third distributor 25 and the fourth distributor 18 all adopt a multi-point uniform material distribution structure, that is, each distributor contains a plurality of uniformly distributed, downward discharge nozzles, and the material blocking plates 4 are distributed below each discharge nozzle.

[0040] In other embodiments, the material blocking plate may not be provided when the material discharging and dispersing capabilities of each distributor are sufficient.

[0041] In this embodiment, the first bottom flue 1, the first upper flue 3, the second bottom flue 14, the second upper flue 16, the first pipe 13 and the second pipe 27 are all provided with guide plates 32 for guiding the flow of smoke to reduce vortexes and reduce resistance. Specifically, the guide plates 32 are arranged at the turning positions of each flue or pipe.

[0042] In other embodiments, the guide plate may not be provided when the pipe bending angle is increased.

[0043] In this embodiment, the first dust removal box 7 and the second dust removal box 19 are both bag dust collectors.

[0044] In other embodiments, the first dust removal box and the second dust removal box can be any one of an electrostatic precipitator, a bag dust collector and an electric bag composite dust collector respectively.

[0045] In this embodiment, the first separator 2 and the second separator 15 are both cyclone separators, which can separate 70% of the solids.

[0046] In other embodiments, the first separator and the second separator may also be other types of gas-solid separation devices.

[0047] In this embodiment, the second distributor 6 is connected to a first pneumatic chute 5 for conveying corresponding fresh defluorination material, and the fourth distributor 18 is connected to a second pneumatic chute 17 for conveying fresh desulfurization material. The arrangement slope of the first pneumatic chute 5 and the second pneumatic chute 17 is greater than 1%.

[0048] In this embodiment, the first ash hopper 8 at the bottom of the first dust removal box 7 and the second ash hopper 20 at the bottom of the second dust removal box 19 are equipped with level meters to avoid internal material accumulation. The discharge port of the first ash hopper 8 is connected to the feed port of the first return box 9, and the discharge port of the second ash hopper 20 is connected to the feed port of the second return box 22.

[0049] The flue gas defluorination, desulfurization and dust removal purification system can be constructed in multiple parallel ways as needed. When in parallel, a regulating valve is set at the inlet of the first bottom flue 1 of each group of flue gas defluorination, desulfurization and dust removal purification systems to ensure that the flue gas volume entering each group of flue gas defluorination, desulfurization and dust removal purification systems is uniform. The second pipelines 27 of each group of flue gas defluorination, desulfurization and dust removal purification systems are collected and introduced into the chimney 31 through the induced draft fan 30 for discharge. Fresh defluorination agent and fresh desulfurization agent are evenly distributed through the horizontal material distribution device before being added to the first pneumatic chute 5 and the second pneumatic chute 17 respectively, and then sent to the second hopper and the fourth distributor 18.

[0050] In the above description, the material refers to fluorine-carrying defluorination material or sulfur-carrying desulfurization material.

[0051] During operation, first, the flue gas is passed into the first bottom flue 1, and then the fluorine-containing defluorination material added into the first bottom flue 1 by the first distributor 11 undergoes the first defluorination reaction, the solid-gas mixture of the flue gas and the fluorine-containing defluorination material after the reaction enters the first separator 2 for separation, the flue gas after separation enters the first upper flue 3, the fluorine-containing defluorination material enters the first return box 9, the second distributor 6 adds fresh defluorination material into the first upper flue 3, the flue gas and the fresh defluorination material undergo the second defluorination reaction, the fresh defluorination material reacts to generate fluorine-containing defluorination material and enters the first dust removal box 7 together with the flue gas for filtration, the filtered flue gas enters the next step, the fluorine-containing defluorination material enters the first return box 9, one discharge port of the first return box 9 conveys the fluorine-containing defluorination material for recycling to the first distributor 11, and the other discharge port is used to discharge the fluorine-containing defluorination material;

[0052] Second, the flue gas transported from the previous step is passed into the second bottom flue 14, and then the sulfur-carrying desulfurization material added into the second bottom flue 14 by the third distributor 25 is subjected to the first desulfurization reaction. The solid-gas mixture of the flue gas and the sulfur-carrying desulfurization material after the reaction enters the second separator 15 for separation. After separation, the flue gas enters the second upper flue 16, and the sulfur-carrying desulfurization material enters the second return box 22. The fourth distributor 18 adds fresh desulfurization material into the second upper flue 16, and the flue gas and the fresh desulfurization material undergo a second desulfurization reaction. The fresh desulfurization material The fluorine-containing desulfurization material is generated by the reaction and enters the second dust removal box 19 for filtration together with the flue gas. The filtered flue gas enters the next step, and the sulfur-containing desulfurization material enters the second return box 22. One discharge port of the second return box 22 conveys the sulfur-containing desulfurization material for recycling to the third distributor 25, and the other discharge port is used to discharge the sulfur-containing desulfurization material. When the sulfur-containing desulfurization material enters the second return box 22, the spiral stirrer 23 is started to stir the sulfur-containing desulfurization material, and the nozzle 21 is made to spray process water to humidify the sulfur-containing desulfurization material to ensure the fluidity of the sulfur-containing desulfurization material.

[0053] Third, the treated flue gas delivered from the previous step is sent to the induced draft fan 30 through a pipeline and is drawn into the chimney 31 by the induced draft fan 30 and then discharged.

[0054] In the above process, fluidizing air for promoting the flow of fluorine-containing defluorination materials is introduced into the bottom of the first return box 9 and the bottom of the first dust removal box 7, and fluidizing air for promoting the flow of sulfur-containing desulfurization materials is also introduced into the bottom of the second return box 22 and the bottom of the second dust removal box. The fluidizing air is provided by the fluidizing fan 28; after the flue gas is discharged from the second dust removal box 19, it exchanges heat with the gas heat exchanger 29, and the fluidizing fan 28 extracts hot air from the gas heat exchanger 29. The flue gas after heat exchange is drawn into the chimney 31 by the induced draft fan 30.

[0055] The present invention does not require a traditional desulfurization tower, so the system occupies a small area and has a low construction cost. The resistance of the system operation is reduced, and the total resistance of the entire system is within 3500Pa. It is particularly suitable for treating the flue gas of aluminum electrolysis cells with low sulfur dioxide concentration and large flue gas volume or the purification of similar flue gas; the defluorination and dust removal section and the desulfurization and dust removal section of the present invention both adopt a two-stage reaction process, that is, the high-concentration flue gas is first subjected to an adsorption reaction with the recycled material (fluorine-carrying defluorination material or sulfur-carrying desulfurization material), and the low-concentration flue gas after the reaction is then reacted with the newly added material (defluorination material or desulfurization material). The two-stage reaction can obtain a better purification effect; the materials of the present invention (fluorine-carrying defluorination material, sulfur-carrying desulfurization material, defluorination material, desulfurization material) are all added from top to bottom, and the flue gas It contacts and mixes with the material from bottom to top, and the reverse reaction makes the reaction proceed more fully; the defluorination and dust removal section and the desulfurization and dust removal section of the present invention are respectively provided with a first separator 2 and a second separator 15, and the first separator 2 and the second separator 15 can separate the material and the flue gas to a certain extent (separation efficiency is about 70%), thereby reducing the corresponding operation load of the first dust removal box 7 and the second dust removal box 19, and reducing the system construction cost and operation cost; in the defluorination and dust removal section and the desulfurization and dust removal section of the present invention, the first return box 9 and the second return box 22 can both provide materials for recycling, which can increase the number of times the material re-participates in the reaction, increase the material concentration, enable the material to fully react with the flue gas, and improve the purification efficiency of the system.

[0056] A flue gas defluorination, desulfurization and dust removal purification process of the present invention comprises the following steps:

[0057] Step one, passing the flue gas into the first bottom flue, and then carrying out the first defluorination reaction with the fluorine-carrying defluorination material added into the first bottom flue by the first distributor, the flue gas after the reaction and the solid-gas mixture of the fluorine-carrying defluorination material enter the first separator for separation, the flue gas after separation enters the first upper flue, the fluorine-carrying defluorination material enters the first return box, the second distributor adds fresh defluorination material into the first upper flue, the flue gas and the fresh defluorination material carry out the second defluorination reaction, the fresh defluorination material reacts to generate fluorine-carrying defluorination material and enters the first dust removal box together with the flue gas for filtration, the filtered flue gas enters the next step, the fluorine-carrying defluorination material enters the first return box, one discharge port of the first return box conveys the fluorine-carrying defluorination material for recycling to the first distributor, and the other discharge port is used to discharge the fluorine-carrying defluorination material;

[0058] Step 2: The flue gas delivered from the previous step is passed into the second bottom flue, and then the third distributor adds the sulfur-carrying desulfurization material into the second bottom flue for the first desulfurization reaction. The flue gas and the solid-gas mixture of the sulfur-carrying desulfurization material after the reaction enter the second separator for separation. After separation, the flue gas enters the second upper flue, and the sulfur-carrying desulfurization material enters the second return box. The fourth distributor adds fresh desulfurization material into the second upper flue, and the flue gas and the fresh desulfurization material undergo a second desulfurization reaction. The fresh desulfurization material reacts Fluorine-containing desulfurization material should be generated and enter the second dust removal box for filtration together with the flue gas. The filtered flue gas enters the next step, and the sulfur-containing desulfurization material enters the second return box. One discharge port of the second return box conveys the sulfur-containing desulfurization material for recycling to the third distributor, and the other discharge port is used to discharge the sulfur-containing desulfurization material. When the sulfur-containing desulfurization material enters the second return box, the spiral stirrer is started to stir the sulfur-containing desulfurization material, and the nozzle is allowed to spray process water to humidify the sulfur-containing desulfurization material to ensure the fluidity of the sulfur-containing desulfurization material.

[0059] Step three, the treated flue gas delivered from the previous step is sent to the induced draft fan through a pipeline and is drawn into the chimney by the induced draft fan and then discharged.

[0060] Furthermore, fluidizing air for promoting the flow of fluorine-containing defluorination materials is introduced into the bottom of the first return box and the bottom of the first dust removal box, and fluidizing air for promoting the flow of sulfur-containing desulfurization materials is also introduced into the bottom of the second return box and the bottom of the second dust removal box, and the fluidizing air is provided by a fluidizing fan.

[0061] Furthermore, after being discharged from the second dust removal box, the flue gas exchanges heat with the gas heat exchanger, the fluidizing fan extracts hot air from the gas heat exchanger, and the flue gas after heat exchange is drawn into the chimney by the induced draft fan.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A flue gas defluorination, desulfurization and dust removal purification system, characterized by: It includes a defluorination and dust removal section, a desulfurization and dust removal section, an induced draft fan and a chimney connected in sequence; The defluorination and dust removal section includes a first bottom flue, a first separator, a first upper flue and a first dust removal box connected in sequence, a first distributor for adding fluorine-containing defluorination material is provided in the first bottom flue, a second distributor for adding fresh defluorination material is provided in the first upper flue, and also includes a first return box for collecting and distributing fluorine-containing defluorination material, the discharge ports of the first separator and the first dust removal box for discharging fluorine-containing defluorination material are respectively connected to the feed port of the first return box, the first return box is provided with two discharge ports and one of them is connected to the first distributor so as to convey the fluorine-containing defluorination material for recycling thereto; The desulfurization and dust removal section includes a second bottom flue, a second separator, a second upper flue and a second dust removal box connected in sequence, a third distributor for adding sulfur-containing desulfurization material is provided in the second bottom flue, a fourth distributor for adding fresh desulfurization material is provided in the second upper flue, and also includes a second return box for collecting and distributing fluorine-containing defluorination material, the discharge ports of the second separator and the second dust removal box are respectively connected to the feed port of the second return box, the second return box is provided with two discharge ports and one of them is connected to the third distributor so as to convey the sulfur-containing desulfurization material for recycling thereto, the second return box is provided with a spiral stirrer for stirring the collected sulfur-containing desulfurization material and a nozzle for spraying process water to humidify the collected sulfur-containing desulfurization material; The second bottom flue of the desulfurization and dust removal section is connected to the first dust removal box pipe of the defluorination and dust removal section, and the air inlet and air outlet of the induced draft fan are respectively connected to the second dust removal box and the chimney pipe; Wherein, the first dust removal box and the second dust removal box are any one of an electrostatic precipitator, a bag dust collector and an electric bag composite dust collector, respectively, and the first separator and the second separator are both cyclone separators.

2. A flue gas defluorination, desulfurization and dust removal purification system according to claim 1, characterized in that: A gas heat exchanger for exchanging heat with flue gas and a fluidizing fan for extracting hot air from the gas heat exchanger are provided on the pipeline between the induced draft fan and the second dust removal box. The air outlet of the fluidizing fan is respectively connected to the bottom of the first dust removal box, the bottom of the second dust removal box, the bottom of the first return box and the bottom pipeline of the second return box to supply fluidizing air.

3. A flue gas defluorination, desulfurization and dust removal purification system according to claim 2, characterized in that: A first valve is provided on each of the two discharge ports of the first return box, and the first valve connected to the first distributor is adjusted to control the circulation amount of the fluorine-containing defluorination material; a second valve is provided on each of the two discharge ports of the second return box, and the second valve connected to the third distributor is adjusted to control the circulation amount of the sulfur-containing desulfurization material.

4. A flue gas defluorination, desulfurization and dust removal purification system according to claim 1, 2 or 3, characterized in that: Material blocking plates for dispersing the material so as to facilitate it to follow the flow of smoke are arranged below the first distributor, the second distributor, the third distributor and the fourth distributor.

5. A flue gas defluorination, desulfurization and dust removal purification system according to claim 4, characterized in that: The first bottom flue, the first upper flue, the second bottom flue and the second upper flue are all provided with guide plates for guiding the flow of smoke to reduce vortex and lower resistance.

6. A flue gas defluorination, desulfurization and dust removal purification process, characterized in that: The following steps are involved: Step one, passing the flue gas into the first bottom flue, and then carrying out the first defluorination reaction with the fluorine-carrying defluorination material added into the first bottom flue by the first distributor, the flue gas after the reaction and the solid-gas mixture of the fluorine-carrying defluorination material enter the first separator for separation, the flue gas after separation enters the first upper flue, the fluorine-carrying defluorination material enters the first return box, the second distributor adds fresh defluorination material into the first upper flue, the flue gas and the fresh defluorination material carry out the second defluorination reaction, the fresh defluorination material reacts to generate fluorine-carrying defluorination material and enters the first dust removal box together with the flue gas for filtration, the filtered flue gas enters the next step, the fluorine-carrying defluorination material enters the first return box, one discharge port of the first return box conveys the fluorine-carrying defluorination material for recycling to the first distributor, and the other discharge port is used to discharge the fluorine-carrying defluorination material; Step 2: The flue gas delivered from the previous step is passed into the second bottom flue, and then the third distributor adds the sulfur-carrying desulfurization material into the second bottom flue for the first desulfurization reaction. The flue gas and the solid-gas mixture of the sulfur-carrying desulfurization material after the reaction enter the second separator for separation. After separation, the flue gas enters the second upper flue, and the sulfur-carrying desulfurization material enters the second return box. The fourth distributor adds fresh desulfurization material into the second upper flue, and the flue gas and the fresh desulfurization material undergo a second desulfurization reaction. The fresh desulfurization material reacts Fluorine-containing desulfurization material should be generated and enter the second dust removal box for filtration together with the flue gas. The filtered flue gas enters the next step, and the sulfur-containing desulfurization material enters the second return box. One discharge port of the second return box conveys the sulfur-containing desulfurization material for recycling to the third distributor, and the other discharge port is used to discharge the sulfur-containing desulfurization material. When the sulfur-containing desulfurization material enters the second return box, the spiral stirrer is started to stir the sulfur-containing desulfurization material, and the nozzle is allowed to spray process water to humidify the sulfur-containing desulfurization material to ensure the fluidity of the sulfur-containing desulfurization material. Step three, the treated flue gas delivered from the previous step is sent to the induced draft fan through a pipeline and is drawn into the chimney by the induced draft fan and then discharged.

7. A flue gas defluorination, desulfurization and dust removal purification process according to claim 6, characterized in that: Fluidizing air for promoting the flow of fluorine-containing defluorination materials is introduced into the bottom of the first return box and the bottom of the first dust removal box. Fluidizing air for promoting the flow of sulfur-containing desulfurization materials is also introduced into the bottom of the second return box and the bottom of the second dust removal box. The fluidizing air is provided by a fluidizing fan.

8. A flue gas defluorination, desulfurization and dust removal purification process according to claim 7, characterized in that: After being discharged from the second dust removal box, the flue gas exchanges heat with the gas heat exchanger, the fluidizing fan extracts hot air from the gas heat exchanger, and the flue gas after heat exchange is drawn into the chimney by the induced draft fan.

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