Flue gas treatment system

Abstract

The utility model provides a flue gas treatment system which comprises a boiler, and the boiler is further sequentially connected with a dust removal device, a concentration tower, an absorption tower and a discharge chimney in series. A liquid storage tank is arranged at the bottom of the absorption tower and is respectively connected with the concentration tower and the ammonia water tank. According to the system, the concentration tower and the absorption tower are arranged, ammonia water absorption liquid generated after desulfurization in the absorption tower is input into the concentration tower, flue gas subjected to dust removal through the dust removal device is subjected to cooling and preliminary desulfurization, meanwhile, moisture in the absorption liquid is evaporated through preheating of the flue gas, and concentration of the absorption liquid is achieved. According to the system, the waste heat of the flue gas is used for concentrating the absorption liquid through matched use of the equipment, the system has the advantages of fully utilizing the waste heat of the flue gas and saving energy, and the defect that in a traditional flue gas treatment mode, the generated absorption liquid needs to be additionally treated with energy, so that the energy consumption is large, and the production cost is increased is overcome.

Description

Technical Field

[0001] The present application relates to the technical field of boiler flue gas treatment, and in particular to a flue gas treatment system. Background Art

[0002] Thermal power plants are major consumers of coal and also generate a lot of dust, SO2, NO x (nitrogen oxides) are major emitters. SO2 and NO x (Nitrogen oxides) are also the main factors causing pollution phenomena such as acid rain and photochemical smog, which have serious impacts on the ecological environment and human health. The state has put forward more and more stringent environmental protection requirements for thermal power plants, among which the emission of major atmospheric pollutants such as sulfur dioxide, nitrogen oxides, smoke (dust) in flue gas is subject to increasingly stringent control standards. The existing flue gas treatment mainly purifies the flue gas discharged by the boiler through denitrification, dust removal, desulfurization and other processes. Among them, denitrification is generally completed in the furnace (SNCR method) or flue (SCR method), and desulfurization is generally carried out by flue gas post-treatment. The traditional flue gas desulfurization methods mainly include lime milk washing desulfurization and ammonia washing desulfurization. Due to the unstable quality of gypsum produced by lime milk desulfurization, and its large output, it is difficult to handle in time, which will lead to product backlogs. Therefore, many manufacturers will discard the by-product gypsum, which is obviously not advisable. Therefore, in order to avoid the above-mentioned adverse situations, many manufacturers also use ammonia washing flue gas desulfurization.

[0003] The byproduct of ammonia washing and desulfurization is ammonium sulfate, which is widely used and easier to sell than gypsum. In the existing ammonia washing and desulfurization process, the dust-removed flue gas is directly passed into the absorption tower and absorbed by ammonia. However, this method requires additional energy to concentrate and refine the saturated absorption liquid (i.e., the solution containing ammonium sulfate). This method not only requires additional energy processing, resulting in increased production costs, but also fails to fully utilize the waste heat in the flue gas, resulting in energy waste. Utility Model Content

[0004] The present application provides a flue gas treatment system to solve the problem that in the above-mentioned existing flue gas treatment methods, the generated absorption liquid needs to consume additional energy to process, which leads to increased production costs and energy waste.

[0005] The present application provides a flue gas treatment system, including a boiler, which is also connected in series with a dust removal device, a concentration tower, an absorption tower and an emission chimney;

[0006] A liquid storage tank is provided at the bottom of the absorption tower, and the liquid storage tank is also connected to the concentration tower and the ammonia water tank respectively;

[0007] A first spray layer is arranged at the upper part of the concentration tower, an air inlet is opened at the top, a first circulation port is opened at the bottom, and an air outlet is opened at the side; the first circulation port is connected to the first spray layer through a first circulation pump; the concentration tower is also connected to the crystallization tank.

[0008] Optionally, the absorption tower further comprises a smoke outlet at the top and a second circulation port at the side of the liquid storage tank, and a smoke inlet at the side of the tower body;

[0009] A first partition is provided in the absorption tower to divide the tower into an upper denitration zone and a lower desulfurization zone; a first connecting pipe passes through the first partition and extends into the denitration zone to connect the denitration zone and the desulfurization zone;

[0010] A second partition is provided in the denitration zone to divide the denitration zone into an upper spray zone and a lower water washing zone; a second connecting pipe passes through the second partition and extends into the spray zone to connect the spray zone and the water washing zone;

[0011] A second spray layer is provided in the upper part of the desulfurization zone, and the second spray layer is connected to the second circulation port of the storage tank through a second circulation pump;

[0012] A third circulation port is provided on the side of the tower body near the first partition in the water washing area, and the third circulation port is connected to the water washing tank, the third circulation pump and the third spray layer at the upper part of the water washing area in sequence;

[0013] A fourth circulation port is provided on the side of the tower body near the second partition in the spraying area, and the fourth circulation port is connected with the alkali washing tank, the fourth circulation pump and the fourth spraying layer at the upper part of the spraying area in sequence.

[0014] Optionally, an air distribution pipe is provided in the liquid storage tank, and the air distribution pipe is connected to the fan.

[0015] Optionally, a plurality of ammonia spray guns are provided on the boiler near the flame folding angle;

[0016] A plurality of ammonia spray guns are also connected to the ammonia storage tank.

[0017] Optionally, the absorption tower is also connected to an ozone generator.

[0018] Optionally, the dust removal device includes a cyclone dust collector and a bag dust collector connected in series.

[0019] Optionally, a heat exchanger is further provided between the first circulation port and the first circulation pump.

[0020] The system of the present application, by setting up a concentration tower and an absorption tower, inputs the ammonia absorption liquid produced after desulfurization in the absorption tower into the concentration tower, cools down and preliminarily desulfurizes the flue gas after dust removal by the dust removal device, and simultaneously utilizes the preheating of the flue gas to evaporate the water in the absorption liquid to achieve the concentration of the absorption liquid. The system of the present application uses the waste heat of the flue gas to concentrate the absorption liquid through the coordinated use of the above-mentioned equipment, which has the advantages of fully utilizing the waste heat of the flue gas and saving energy, and overcomes the disadvantages of the traditional flue gas treatment method that the generated absorption liquid needs to consume additional energy for treatment, resulting in high energy consumption, increased production costs and waste of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of a flue gas treatment system provided in one embodiment of the present application;

[0023] Figure 2 A schematic diagram of the structure of a concentration tower provided in one embodiment of the present application;

[0024] Figure 3 A schematic diagram of the structure of an absorption tower provided in one embodiment of the present application;

[0025] Figure 4 A schematic diagram of a flue gas treatment system provided in another embodiment of the present application;

[0026] Figure 5 A schematic diagram of a flue gas treatment system provided in yet another embodiment of the present application;

[0027] Figure 6 A schematic diagram of a flue gas treatment system provided in yet another embodiment of the present application.

[0028] Description of reference numerals:

[0029] 1. Boiler; 2. Dust removal device; 3. Concentration tower; 4. Absorption tower; 5. Emission chimney; 6. Ammonia tank; 7. Ozone generator; 11. Ammonia spray gun; 12. Ammonia storage tank; 21. Cyclone dust collector; 22. Bag filter; 31. First spray layer; 32. First circulation pump; 33. Crystallization tank; 34. Heat exchanger; 41. Liquid storage tank; 42. First partition; 43. Second partition; 44. Second spray layer; 61. Air distribution pipe; 62. Fan; 301. Air inlet; 302, first circulation port; 303, air outlet; 401, flue gas outlet; 402, second circulation port; 403, flue gas inlet; 404, third circulation port; 405, fourth circulation port; 421, first connecting pipe; 422, water washing tank; 423, third circulation pump; 424, third spray layer; 431, second connecting pipe; 432, alkali washing tank; 433, fourth circulation pump; 434, fourth spray layer; 441, second circulation pump; 601, exhaust port. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0031] The present application provides a flue gas treatment system, such as Figure 1 and Figure 2 As shown, it includes a boiler 1, which is also connected in series with a dust removal device 2, a concentration tower 3, an absorption tower 4 and an emission chimney 5;

[0032] A liquid storage tank 41 is provided at the bottom of the absorption tower 4, and the liquid storage tank 41 is also connected to the concentration tower 3 and the ammonia water tank 6 respectively;

[0033] A first spray layer 31 is arranged at the upper part of the concentration tower 3, an air inlet 301 is opened at the top, a first circulation port 302 is opened at the bottom, and an air outlet 303 is opened on the side; the first circulation port 302 is connected to the first spray layer 31 through a first circulation pump 32; the concentration tower 3 is also connected to a crystallization tank 33.

[0034] When in use, the flue gas discharged from the boiler 1 enters the dust removal device 2 to remove the dust and other particles carried in the flue gas. The dust-removed flue gas is output from the dust removal device 2 and enters the concentration tower 3 through the air inlet 301 at the top of the concentration tower 3. The absorption liquid sprayed by the first spray layer 31 (in this application, the ammonium sulfate solution produced in the desulfurization process in the absorption tower 4) washes and removes the fine dust in the flue gas that cannot be removed by the dust removal device 2, and the absorption liquid contacts the flue gas to transfer mass and heat with the flue gas, absorbing sulfur dioxide in the flue gas while reducing the temperature of the flue gas. While the absorption liquid transfers heat with the flue gas, part of the water in the absorption liquid evaporates into water vapor (to achieve the purpose of concentration), and enters the absorption tower 4 together with the flue gas for subsequent treatment. The absorption liquid after mass transfer and heat exchange with the flue gas falls to the bottom of the concentration tower 3, is sucked from the first circulation port 302 by the first circulation pump 32, and then pumped to the first spray layer 31 for circulation washing (it can also be pumped to the first spray layer 31 after cooling). The absorption liquid concentrated to a certain concentration in the concentration tower 3 is discharged from the bottom of the tower to the crystallization tank 33 for crystallization.

[0035] The flue gas cooled, dust-removed and preliminarily desulfurized in the concentration tower 3 enters the absorption tower 4 for desulfurization, denitrification and further dust removal to purify the flue gas, and the purified flue gas is discharged into the emission chimney 5 for discharge.

[0036] The system of the present application, by setting up a concentration tower 3 and an absorption tower 4, inputs the ammonia absorption liquid produced after desulfurization in the absorption tower 4 into the concentration tower 3, cools down and preliminarily desulfurizes the flue gas after dust removal by the dust removal device 2, and simultaneously evaporates the water in the absorption liquid by preheating the flue gas to achieve the concentration of the absorption liquid. The system of the present application uses the waste heat of the flue gas to concentrate the absorption liquid through the coordinated use of the above-mentioned equipment, which has the advantages of fully utilizing the waste heat of the flue gas and saving energy, and overcomes the disadvantages of the traditional flue gas treatment method that the generated absorption liquid needs to consume additional energy to process, resulting in high energy consumption, increased production costs and energy waste.

[0037] Alternatively, if Figure 3 As shown, the absorption tower 4 further includes a smoke outlet 401 at the top, a second circulation port 402 at the side of the liquid storage tank 41, and a smoke inlet 403 at the side of the tower body;

[0038] A first partition 42 is provided in the absorption tower 4 to divide the tower into an upper denitration zone and a lower desulfurization zone; a first connecting pipe 421 passes through the first partition 42 and extends into the denitration zone to connect the denitration zone and the desulfurization zone;

[0039] A second partition 43 is provided in the denitration zone to divide the denitration zone into an upper spray zone and a lower water washing zone; a second connecting pipe 431 passes through the second partition 43 and extends into the spray zone to connect the spray zone and the water washing zone;

[0040] A second spray layer 44 is provided in the upper part of the desulfurization zone, and the second spray layer 44 is connected to the second circulation port 402 through a second circulation pump 441;

[0041] A third circulation port 404 is provided on the side of the tower body near the first partition plate 42 in the water washing area, and the third circulation port 404 is connected to the water washing tank 422, the third circulation pump 423 and the third spray layer 424 at the upper part of the water washing area in sequence;

[0042] A fourth circulation port 405 is provided on the side of the tower body near the second partition plate 43 in the spraying area, and the fourth circulation port 405 is sequentially connected to the alkali washing tank 432, the fourth circulation pump 433 and the fourth spraying layer 434 at the upper part of the spraying area.

[0043] In the present application, when in use, the flue gas cooled, dusted and preliminarily desulfurized in the concentration tower 3 enters the absorption tower 4 from the flue gas inlet 403 of the absorption tower 4, and the absorption liquid (here the absorption liquid is ammonia water and ammonia water that absorbs part of sulfur dioxide) sprayed from the second spray layer 44 at the top of the desulfurization zone is sprayed from top to bottom to counter-flow mass and heat with the flue gas, so as to remove the sulfur in the flue gas. The ammonia water (ammonia water and sulfur dioxide are combined to form ammonium sulfite) that absorbs sulfur oxides in the desulfurization zone falls into the liquid reservoir 41, and then is pumped into the second spray layer 44 by the second circulation pump 441 for recycling. When the concentration of ammonium sulfate in the liquid reservoir 41 reaches a certain value, the absorption liquid in the liquid reservoir 41 is transferred to the concentration tower 3 for concentration.

[0044] The nitrogen oxides that cannot be removed and the ammonia carried by the flue gas in the desulfurization zone enter the water washing zone with the flue gas through the first connecting pipe 421. The ammonia and residual sulfur oxides in the flue gas are washed and removed by the clean water sprayed by the third spray layer 424. The washing water in the water washing zone is discharged from the third circulation port 404, enters the water washing tank 422, and is pumped into the third spray layer 424 for recycling through the third circulation pump 423. When the concentration of the washing water (ammonium sulfate, ammonium sulfite) in the water washing tank 422 reaches a certain value, the washing liquid in the water washing tank 422 is transferred to the liquid storage tank 41 at the bottom of the absorption tower 4 for use.

[0045] The nitrogen oxides in the flue gas enter the spraying area through the second connecting pipe 431 and are sprayed and absorbed by the dilute alkali solution (a sodium hydroxide aqueous solution with a concentration of 10-15%) sprayed by the fourth spray layer 434, thereby absorbing and removing the nitrogen oxides in the flue gas, thereby purifying the flue gas. The purified flue gas is defogged by the demister and then discharged into the discharge chimney 5 for discharge. The dilute alkali solution that absorbs the nitrogen oxides in the spraying area flows into the alkali washing tank 432 through the fourth circulation port 405, and is sucked and pumped into the fourth spray layer 434 by the fourth circulation pump 433 for recycling. When the pH value of the alkali washing tank 432 is neutral, the solution in the alkali washing tank 432 is discharged to the wastewater treatment section or the nitrate treatment section for treatment.

[0046] In the present application, hoods are also provided at the upper ends of the first connecting pipe 421 and the second connecting pipe 431 .

[0047] Optionally, an air distribution pipe 61 is provided in the liquid storage tank 41 , and the air distribution pipe 61 is connected to the fan 62 .

[0048] In the present application, since ammonia absorbs sulfur oxides (mainly sulfur dioxide) and then reacts to generate ammonium sulfite, which is easily decomposed into sulfur dioxide and ammonia, an air distribution pipe 61 is provided, and air is blown into the absorption liquid through the air distribution pipe 61 by a blower 62, and the ammonium sulfite is oxidized to generate ammonium sulfate by oxygen in the air, thereby achieving the purpose of desulfurization. Similarly, air can also be blown into the concentration tower 3 to oxidize the ammonium sulfite formed by the initial absorption of sulfur oxides in the concentration tower 3 into ammonium sulfate.

[0049] Alternatively, if Figure 4 As shown, a plurality of ammonia spray guns 11 are also provided on the boiler 1 near the flame folding angle;

[0050] The plurality of ammonia water spray guns 11 are also connected to the ammonia water storage tank 12 .

[0051] In the present application, when in use, when the boiler 1 is working normally, the ammonia water (concentration of 15-25wt%) in the ammonia water storage tank 12 is sprayed into the furnace near the flame folding angle through the ammonia water spray gun 11, and the nitrogen oxides generated by the combustion of the ammonia water and the fuel (generally coal) in the furnace undergo an oxidation-reduction reaction at high temperature (900-1150°C) to reduce the nitrogen oxides into nitrogen gas, which is discharged with the flue gas.

[0052] Alternatively, if Figure 5 As shown, the absorption tower 4 is also connected to an ozone generator 7 .

[0053] In the present application, since the flue gas also contains some nitrogen oxides, the reaction of low-valent nitrogen oxides with alkali solution is slow, which can easily cause the nitrogen oxides in the exhaust gas to exceed the standard; while the reaction of high-valent nitrogen oxides with alkali solution is fast, which can easily remove the nitrogen oxides in the flue gas. Therefore, an ozone generator 7 is set to generate ozone, which is mixed with the flue gas output by the concentration tower 3 to oxidize the low-valent nitrogen oxides in the flue gas into high-valent nitrogen oxides, and then output to the absorption tower 4, thereby improving the removal rate of nitrogen oxides.

[0054] Alternatively, if Figure 6 As shown, the dust removal device 2 includes a cyclone dust collector 21 and a bag dust collector 22 which are connected in series.

[0055] In the present application, the cyclone dust collector 21 and the bag dust collector 22 are dry dust removal devices. Using the above devices to remove dust from flue gas can avoid the wastewater generated during wet dust removal, and the cyclone dust collector 21 and the bag dust collector 22 are used in series to effectively improve the dust removal efficiency.

[0056] Alternatively, if Figure 2 and Figure 6 As shown, a heat exchanger 34 is further provided between the first circulation port 302 and the first circulation pump 32 .

[0057] In the present application, since the flue gas entering the concentration tower 3 has a certain temperature, the temperature of the washing liquid rises after the heat exchange with the flue gas. During the circulation process, the high temperature of the absorption liquid not only evaporates too quickly, but also causes the absorption liquid to be unable to cool the flue gas. Therefore, a heat exchanger 34 is set to cool the circulating absorption liquid to overcome the disadvantages caused by the above-mentioned increase in the absorption liquid temperature.

[0058] A flue gas treatment system, the working process of which is as follows:

[0059] When in use, when the boiler 1 is working normally, the ammonia water (concentration of 15-25wt%) in the ammonia water storage tank 12 is sprayed into the furnace near the flame folding angle through the ammonia water spray gun 11. The nitrogen oxides generated by the combustion of the ammonia water and the fuel (generally coal) in the furnace undergo an oxidation-reduction reaction at high temperature (900-1150°C) to reduce the nitrogen oxides into nitrogen gas, which is discharged with the flue gas.

[0060] The flue gas discharged from the boiler 1 enters the dust removal device 2, and passes through the two-stage dust removal of the cyclone dust collector 21 and the bag dust collector 22 in sequence to remove the dust and other particles carried in the flue gas. The dust-removed flue gas is output from the dust removal device 2, and enters the concentration tower 3 through the air inlet 301 at the top of the concentration tower 3. The absorption liquid sprayed by the first spray layer 31 (in this application, the ammonium sulfate solution produced by the desulfurization process in the absorption tower 4) washes away the fine dust in the flue gas that cannot be removed by the dust removal device, and the absorption liquid contacts the flue gas to transfer mass and heat with the flue gas, absorbing the sulfur dioxide in the flue gas while reducing the temperature of the flue gas. While the absorption liquid transfers heat with the flue gas, part of the water in the absorption liquid evaporates into water vapor (to achieve the purpose of concentration), and enters the absorption tower 4 together with the flue gas for subsequent treatment. The absorption liquid after mass transfer and heat exchange with the flue gas falls to the bottom of the concentration tower 3, is sucked from the first circulation port 302 by the first circulation pump 32, cooled by the heat exchanger 34, and then pumped to the first spray layer 31 for circulation washing. The absorption liquid concentrated to a certain concentration in the concentration tower 3 is discharged from the bottom of the tower to the crystallization tank 33 for crystallization.

[0061] The flue gas cooled, dusted and preliminarily desulfurized in the concentration tower 3 enters the absorption tower 4 from the flue gas inlet 403 of the absorption tower 4 together with the ozone output from the ozone generator 7, and the absorption liquid (here the absorption liquid is ammonia water and ammonia water that absorbs part of sulfur dioxide) sprayed from the second spray layer 44 at the top of the desulfurization zone is sprayed from top to bottom to counter-flow mass transfer and heat transfer with the flue gas, so as to remove sulfur from the flue gas, and the ozone oxidizes the residual nitrogen oxides in the flue gas into high-valent nitrogen oxides. The ammonia water (ammonia water and sulfur dioxide are combined to form ammonium sulfite) that absorbs sulfur oxides in the desulfurization zone falls into the liquid storage tank 41, and the air supplied by the fan 62 is blown into the solution in the liquid storage tank through the air distribution pipe 61, and the oxygen in the air oxidizes the ammonium sulfite to form ammonium sulfate, which is then pumped into the second spray layer 44 through the second circulation pump 441 for recycling. When the concentration of ammonium sulfate in the liquid reservoir 41 reaches a certain value, the absorption liquid in the liquid reservoir 41 is transferred to the concentration tower 3 for concentration.

[0062] The nitrogen oxides that cannot be removed and the ammonia carried by the flue gas in the desulfurization zone enter the water washing zone with the flue gas through the first connecting pipe 421. The ammonia and residual sulfur oxides in the flue gas are washed and removed by the clean water sprayed by the third spray layer 424. The washing water in the water washing zone is discharged from the third circulation port 404, enters the water washing tank 422, and is pumped into the third spray layer 424 for recycling through the third circulation pump 423. When the concentration of the washing water (ammonium sulfate, ammonium sulfite) in the water washing tank 422 reaches a certain value, the washing liquid in the water washing tank 422 is transferred to the liquid storage tank 41 at the bottom of the absorption tower 4 for use.

[0063] The nitrogen oxides in the flue gas enter the spraying area through the second connecting pipe 431 and are sprayed and absorbed by the dilute alkali solution (a sodium hydroxide aqueous solution with a concentration of 10-15%) sprayed by the fourth spray layer 434, thereby absorbing and removing the nitrogen oxides in the flue gas, thereby purifying the flue gas. The purified flue gas is defogged by the demister and then discharged into the discharge chimney 5 for discharge. The dilute alkali solution that absorbs the nitrogen oxides in the spraying area flows into the alkali washing tank 432 through the fourth circulation port 405, and is sucked and pumped into the fourth spray layer 434 by the fourth circulation pump 433 for recycling. When the pH value of the alkali washing tank 432 is neutral, the solution in the alkali washing tank 432 is discharged to the wastewater treatment section or the nitrate treatment section for treatment.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A flue gas treatment system, comprising a boiler (1), characterized in that: The boiler (1) is also connected in series with a dust removal device (2), a concentration tower (3), an absorption tower (4) and an emission chimney (5); A liquid storage tank (41) is provided at the bottom of the absorption tower (4), and the liquid storage tank (41) is also connected to the concentration tower (3) and the ammonia water tank (6) respectively; The upper part of the concentration tower (3) is provided with a first spray layer (31), the top is provided with an air inlet (301), the bottom is provided with a first circulation port (302), and the side is provided with an air outlet (303); the first circulation port (302) is connected to the first spray layer (31) through a first circulation pump (32); the concentration tower (3) is also connected to a crystallization tank (33).

2. The flue gas treatment system according to claim 1, characterized in that: The absorption tower (4) further comprises a smoke outlet (401) at the top, a second circulation port (402) at the side of the liquid storage tank (41), and a smoke inlet (403) at the side of the tower body; The absorption tower (4) is provided with a first partition (42) to divide the tower into an upper denitration zone and a lower desulfurization zone; a first connecting pipe (421) passes through the first partition (42) and extends into the denitration zone to connect the denitration zone and the desulfurization zone; A second partition (43) is provided in the denitration zone to divide the denitration zone into an upper spray zone and a lower water washing zone; a second connecting pipe (431) passes through the second partition (43) and extends into the spray zone to connect the spray zone and the water washing zone in the water washing zone; A second spray layer (44) is provided in the upper part of the desulfurization zone, and the second spray layer (44) is connected to the second circulation port (402) through a second circulation pump (441); A third circulation port (404) is provided on the side of the tower body near the first partition (42) in the water washing zone, and the third circulation port (404) is sequentially connected to the water washing tank (422), the third circulation pump (423) and the third spray layer (424) at the upper part of the water washing zone; A fourth circulation port (405) is provided on the side of the tower body near the second partition plate (43) in the spraying area, and the fourth circulation port (405) is sequentially connected to the alkali washing tank (432), the fourth circulation pump (433) and the fourth spraying layer (434) at the top of the spraying area.

3. The flue gas treatment system according to claim 1, characterized in that: An air distribution pipe (61) is provided in the liquid storage tank (41), and the air distribution pipe (61) is connected to a fan (62).

4. The flue gas treatment system according to claim 1, characterized in that: A plurality of ammonia spray guns (11) are also arranged on the boiler (1) near the flame bending angle; The plurality of ammonia water spray guns (11) are also connected to an ammonia water storage tank (12).

5. The flue gas treatment system according to claim 1, characterized in that: The absorption tower (4) is also connected to an ozone generator (7).

6. The flue gas treatment system according to claim 1, characterized in that: The dust removal device (2) comprises a cyclone dust collector (21) and a bag dust collector (22) which are sequentially connected in series.

7. The flue gas treatment system according to any one of claims 1 to 6, characterized in that: A heat exchanger (34) is also provided between the first circulation port (302) and the first circulation pump (32).

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