Sintering flue gas CO removal system

Abstract

The sintering flue gas CO removal system comprises a sintering machine, a water removal device, a first flue gas purification device, a CO catalytic reactor, a second flue gas purification device and a chimney. According to the utility model, the air bellow below the sintering machine is divided into the decarburization air bellow and the non-decarburization air bellow according to the release rule of flue gas in the sintering process, only the sintering flue gas exhausted by the decarburization air bellow is subjected to CO removal treatment, and the positions of the decarburization air bellow and the non-decarburization air bellow can be determined according to the concentration of pollutants in the air bellow; compared with the prior art, the flue gas amount in the CO catalytic oxidation process is reduced by half, the equipment and CO catalyst cost is reduced by 50%, pollutants such as SO2 and HCl in the first-section flue gas are removed to an extremely low value, and the service life of the CO catalyst is prolonged.

Description

Technical Field

[0001] The utility model relates to a CO removal system, in particular to a sintering flue gas CO removal system, and belongs to the technical field of sintering flue gas purification. Background Art

[0002] The sintering process refers to the process in which raw materials, fuel, flux, return ore and water are mixed and granulated, then added to the sintering machine through the distribution system, the ignition furnace ignites the fuel, and the exhaust locomotive draws air to complete the reaction. After the sintered ore is cooled and screened, it can enter the blast furnace to smelt molten iron. The sintering process is a very important step in the steel manufacturing process.

[0003] Since the flue gas produced during the sintering process contains a large amount of SO2, NO x , dust, CO, VOCs pollutants, and the emission of these pollutants accounts for 90% of the total pollutant emissions of the steel process. Sintering flue gas must be dusted, desulfurized, and denitrified before being discharged. Among the pollutants generated by sintering, there is no standard for CO emissions for the time being. However, the governments of Tangshan, Linfen and other places have issued CO emission limit directives, requiring CO to reach 4000mg / m 3 The CO removal from sintering flue gas is becoming more and more important.

[0004] Catalytic oxidation of CO is one of the best methods for flue gas with a CO concentration below 2%. However, even after desulfurization and denitrification, the sintering flue gas still contains a small amount of SO2, trace amounts of VOCs and HCl, which will have a serious impact on the catalytic efficiency and life of the CO oxidation catalyst. In sintering flue gas with a water content of up to 10%, SO2 forms sulfite by adsorption on the catalyst surface, and then forms stable sulfate with the hydroxide formed by dissociated water, covering the active sites on the catalyst surface. Trace amounts of VOCs form carbon deposits attached to the catalyst surface through incomplete oxidation. HCl will dissociate chloride ions and strongly adsorb on the active sites, and further form chloride salts. Sulfate and carbon deposits begin to decompose at high temperatures above 300 and 400°C, respectively, while the decomposition of chloride salts requires a high temperature of more than 800°C. To reduce their impact, the reaction temperature of CO oxidation should be increased, or the concentrations of SO2, VOCs, and HCl should be reduced. The high-temperature reaction of CO and the addition of a secondary flue gas treatment device after the existing desulfurization and denitrification device will increase costs.

[0005] In the traditional sintering flue gas treatment process, the flue gas extracted by each wind box is often collected and then uniformly subjected to dust removal, desulfurization, and denitrification, and then discharged after meeting the emission standards. The same is true for existing CO removal schemes, such as CN201921889301.9. The disadvantages of this method are large flue gas volume, many types of pollutants, and high concentrations, which make the CO catalyst easily deactivated and CO oxidation removal difficult.

[0006] Since different bellows correspond to different sintering process states, the flue gas generated is also different. A solution has been proposed to improve the processing efficiency and reduce costs by dividing the bellows flue gas into sections and treating them separately. For example, patents CN202220755771.1 and CN201821986443.2 divide the sintering flue gas into three sections, and perform desulfurization or denitrification treatment according to the characteristics of each section of the sintering flue gas. However, there is room for optimization in the above technologies. Utility Model Content

[0007] In view of the need to remove CO from sintering flue gas in the prior art, HCl, SO2, etc. in the sintering flue gas have a serious impact on the catalytic efficiency and life of the CO oxidation catalyst. In addition, there is still a large room for optimization in the existing scheme. The utility model proposes a sintering flue gas CO removal system, which classifies and processes the sintering flue gas according to the concentration of CO, realizes efficient purification of the flue gas, reduces the risk of catalyst poisoning, and prolongs the service life of the catalyst.

[0008] According to an embodiment of the utility model, a sintering flue gas CO removal system is provided.

[0009] A sintering flue gas CO removal system, the system includes a sintering machine, a dehydration device, a first flue gas purification device, a CO catalytic reactor, a second flue gas purification device and a chimney. According to the running direction of the sintering machine, the wind box below the sintering machine is divided into a decarbonization wind box and a non-decarbonization wind box. The decarbonization wind box is connected to the first flue, and the non-decarbonization wind box is connected to the second flue. The first flue is connected to the flue gas inlet of the dehydration device through the first flue gas pipeline, the flue gas outlet of the dehydration device is connected to the flue gas inlet of the first flue gas purification device through the second flue gas pipeline, the flue gas outlet of the first flue gas purification device is connected to the flue gas inlet of the CO catalytic reactor through the third flue gas pipeline, and the flue gas outlet of the CO catalytic reactor is connected to the chimney through the fourth flue gas pipeline. The second flue is connected to the flue gas inlet of the second flue gas purification device through the fifth flue gas pipeline. The flue gas outlet of the second flue gas purification device is connected to the chimney through the sixth flue gas pipeline.

[0010] Preferably, the decarburization bellows are 1 / 3 to 2 / 3 of the bellows close to the sintering machine head, and the remaining bellows are non-decarburization bellows.

[0011] Preferably, according to the running direction of the sintering machine, the wind boxes under the sintering machine are numbered in sequence, namely, wind boxes 1, ..., x, ..., y, the decarburization wind boxes are wind boxes 1 to x, and the non-decarburization wind boxes are wind boxes x+1 to y. The value of x is based on the following: the SO2 concentration in the flue gas of wind boxes 1 to x is less than 250 mg / m 3 (Preferably less than 230 mg / m 3 ) and the HCl concentration is less than 5 mg / m3 (Preferably less than 4 mg / m 3 ).

[0012] Preferably, a is set to an integer greater than or equal to 1 and less than x, and the decarbonization windboxes are windboxes No. a+1 to No. x. The non-decarbonization windboxes are windboxes No. 1 to No. a and windboxes No. x+1 to No. y. The value of a is based on the following: the average CO concentration of the flue gas from windboxes No. 1 to No. a is not higher than the average CO concentration of the flue gas from windboxes No. (x+1) to No. y.

[0013] Preferably, the system further comprises a first heat exchange device. The fifth flue gas duct is interconnected with the third flue gas duct via the first heat exchange device.

[0014] Preferably, the system further comprises a denitration device. The first flue gas purification device is an activated carbon desulfurization tower. The second flue gas purification device is an activated carbon desulfurization and denitration tower. The denitration device is optionally arranged on the third flue gas duct or the fourth flue gas duct. The system further comprises a second heat exchange device. The fourth flue gas duct is interconnected with the third flue gas duct through the second heat exchange device.

[0015] Preferably, the system further includes a denitration device. Both the first flue gas purification device and the second flue gas purification device are activated carbon desulfurization devices. The flue gas outlet of the CO catalytic reactor is connected to the flue gas inlet of the denitration device through a fourth flue gas duct. The flue gas outlet of the second flue gas purification device is connected to the flue gas inlet of the denitration device through a sixth flue gas duct. The flue gas outlet of the denitration device is connected to the chimney through a seventh flue gas duct. Preferably, the system further includes a second heat exchange device. The third flue gas duct and the seventh flue gas duct are interconnected through the second heat exchange device.

[0016] Preferably, the system further comprises a heating device, which is arranged at the flue gas outlet of the first flue gas purification device.

[0017] Preferably, the first flue, the second flue, the first flue gas duct, the third flue gas duct and the fifth flue gas duct are all provided with a temperature detection device and / or a CO concentration detection device.

[0018] Preferably, the first flue gas duct and / or the fifth flue gas duct is provided with a dust collector and an induced draft fan.

[0019] Preferably, the water removal device is a condensation water remover.

[0020] In the present invention, the sintering fume generated during the sintering process is extracted, and the components in the sintering fume of each bellows are analyzed. The results are as follows: Figure 3From the figure, we can see that the H2O concentration in the first section of flue gas (i.e., the flue gas from bellows 1-18) is relatively high, and the H2O concentration gradually decreases from the end of the first section (the flue gas from bellows 19). In contrast to H2O, the concentration of HCl in the first section of flue gas is relatively low, and its concentration slowly increases from the end of the first section. In addition, the concentrations of CO and SO2 both increase first and then decrease, and the CO concentration in the middle section of flue gas (the flue gas from bellows 10-18) is the highest, and the SO2 concentration in the middle and rear sections of flue gas (the flue gas from bellows 19-21) is the highest. The concentration change of VOCs is consistent with that of CO. Assuming that Figure 3 The flue gas from bellows No. 1-18 is taken as the first section of flue gas, and the flue gas from bellows No. 19-29 is taken as the second section of flue gas. According to the flue gas volume of each bellows, it can be calculated that the CO concentration in the first section of flue gas is as high as 1-1.5%, while that in the second section of flue gas is only 0.1-0.3%. Therefore, only removing CO from the first section of flue gas can reduce the flue gas volume by half, while achieving CO emission reduction.

[0021] In the utility model, since the CO oxidation catalyst is sensitive to H2O, SO2, VOCs and HCl, such pollutants in the first flue gas need to be removed or reduced before CO removal. The utility model divides the bellows below the sintering machine into a decarbonization bellows and a non-decarbonization bellows, and introduces the sintering flue gas in the decarbonization bellows into the first flue gas purification device. Since the original concentrations of SO2 and HCl in the first flue gas are low, the first flue gas purification device removes pollutants such as SO2 and HCl in the high CO, low SO2 and HCl flue gas to extremely low values ​​at low temperature, reducing their influence on the activity of the CO catalyst and extending the catalyst life. The sintering flue gas in the non-decarbonization bellows is introduced into the second flue gas purification device to complete the purification of the high SO2, HCl and low CO flue gas. Furthermore, according to the changing law of CO concentration in the bellows, the sintering flue gas in bellows No. 1 to a at the sintering machine head is mixed with the flue gas in bellows No. x+1 to y as low CO flue gas, and the sintering flue gas in bellows No. a+1 to x is used as high CO flue gas, thereby reducing the amount of flue gas in the CO removal process.

[0022] In the present utility model, due to the presence of various impurities in the sintering flue gas, the activation temperature of CO oxidation will increase, so before CO enters the CO catalytic reactor, the temperature of the flue gas needs to be increased. Since the temperature of the sintering flue gas in the second flue is relatively high, reaching 280-320°C, the present utility model is provided with a first heat exchange device, and the heat of the high-temperature, low-CO flue gas in the fifth flue gas duct is used to increase the temperature of the high-CO flue gas discharged from the first flue gas purification device by indirect heat exchange. Preferably, the temperature of the flue gas will reach 260-320°C after passing through the CO catalytic reactor and the denitrification device. The present utility model is provided with a second heat exchanger, and the heat of the high-temperature flue gas here is used to increase the temperature of the flue gas before entering the CO catalytic reactor. Further preferably, the present utility model is provided with a heating device to ensure that the temperature of the flue gas entering the CO catalytic reactor is within the required working temperature range of the catalyst to fully remove CO from the flue gas.

[0023] In the present utility model, there are multiple connection modes between the denitrification device, the CO catalytic reactor, the first flue gas purification device and the second flue gas purification device. The first flue gas purification device is an activated carbon desulfurization device. When the second flue gas purification device is an activated carbon desulfurization device, the first flue gas purification device is connected in series with the CO catalytic reactor. The flue gas discharged from the CO catalytic reactor is mixed with the flue gas discharged from the second flue gas purification device and then enters the denitrification device together to remove nitrogen oxides. When the second flue gas purification device is an activated carbon desulfurization and denitrification device, the first flue gas purification device is connected in series with the CO catalytic reactor and the denitrification device, and the positions of the CO catalytic reactor and the denitrification device can be interchanged.

[0024] In the present utility model, the first heat exchange device and the second heat exchange device are both indirect heat exchange devices.

[0025] In the utility model, a temperature detection device is provided to adjust the power of the first heat exchange device, the second heat exchanger and the heating device in real time so that the sintering flue gas before entering the CO catalytic reactor is within the optimal temperature range.

[0026] Compared with the prior art, the utility model has the following beneficial effects:

[0027] 1. The utility model provides a sintering flue gas CO removal system. According to the release law of flue gas in the sintering process, the bellows below the sintering machine are divided into a decarbonization bellows and a non-decarbonization bellows. Only the sintering flue gas discharged from the decarbonization bellows is treated for CO removal, and the positions of the decarbonization bellows and the non-decarbonization bellows can be determined according to the concentration of each pollutant in the bellows, thereby reducing the flue gas volume in the CO catalytic oxidation process by half, reducing the equipment and CO catalyst costs by 50%, removing pollutants such as SO2 and HCl in the first stage of flue gas to extremely low values, and extending the service life of the CO catalyst.

[0028] 2. The utility model provides a sintering flue gas CO removal system, which is provided with a first heat exchange device and a second heat exchanger. According to the characteristics of the system and the flue gas, the waste heat of the sintering flue gas in the non-decarbonization wind box and the flue gas at the outlet of the CO catalytic reactor is fully utilized to reduce the overall energy consumption of the system and save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The utility model provides a structural schematic diagram of a sintering flue gas CO removal system.

[0030] Figure 2 Another structural schematic diagram of a sintering flue gas CO removal system provided by the utility model.

[0031] Figure 3 This is a diagram showing the release patterns of various pollutants during the sintering process.

[0032] Figure numerals: 1, sintering machine; 101: decarbonization bellows; 102: non-decarbonization bellows; 2: dehydration device; 3: first flue gas purification device; 4: CO catalytic reactor; 5: second flue gas purification device; 6: chimney; 7: first heat exchange device; 8: denitrification device; 9: second heat exchange device; 10: heating device; 11: dust collector; 12: induced draft fan; L1: first flue; L2: second flue; G1: first flue gas duct; G2: second flue gas duct; G3: third flue gas duct; G4: fourth flue gas duct; G5: fifth flue gas duct; G6: sixth flue gas duct; G7: seventh flue gas duct. DETAILED DESCRIPTION

[0033] The technical solution of the utility model is illustrated below, and the scope of protection requested for the utility model includes but is not limited to the following embodiments.

[0034] According to an embodiment of the utility model, a sintering flue gas CO removal system is provided.

[0035] A sintering flue gas CO removal system, the system comprises a sintering machine 1, a dehydration device 2, a first flue gas purification device 3, a CO catalytic reactor 4, a second flue gas purification device 5 and a chimney 6. According to the running direction of the sintering machine 1, the wind box below the sintering machine 1 is divided into a decarbonization wind box 101 and a non-decarbonization wind box 102. The decarbonization wind box 101 is connected to the first flue L1, and the non-decarbonization wind box 102 is connected to the second flue L2. The first flue L1 is connected to the flue gas inlet of the dehydration device 2 through the first flue gas pipe G1, the flue gas outlet of the dehydration device 2 is connected to the flue gas inlet of the first flue gas purification device 3 through the second flue gas pipe G2, the flue gas outlet of the first flue gas purification device 3 is connected to the flue gas inlet of the CO catalytic reactor 4 through the third flue gas pipe G3, and the flue gas outlet of the CO catalytic reactor 4 is connected to the chimney 6 through the fourth flue gas pipe G4. The second flue L2 is connected to the flue gas inlet of the second flue gas purification device 5 through the fifth flue gas pipe G5. The flue gas outlet of the second flue gas purification device 5 is connected to the chimney 6 through the sixth flue gas duct G6.

[0036] Preferably, the decarburization bellows 101 are 1 / 3 to 2 / 3 of the bellows close to the head of the sintering machine, and the remaining bellows are non-decarburization bellows 102.

[0037] Preferably, according to the running direction of the sintering machine, the wind boxes under the sintering machine are numbered in sequence, namely, wind boxes 1, ..., x, ..., y, the decarburization wind boxes 101 are wind boxes 1 to x, and the non-decarburization wind boxes 102 are wind boxes x+1 to y. The value of x is based on the following: the SO2 concentration in the flue gas of wind boxes 1 to x is less than 250 mg / m 3 (Preferably less than 230 mg / m 3 ) and the HCl concentration is less than 5 mg / m 3 (Preferably less than 4 mg / m 3 ).

[0038] Preferably, a is set to an integer greater than or equal to 1 and less than x, and the decarbonization windboxes 101 are windboxes No. a+1 to No. x. The non-decarbonization windboxes 102 are windboxes No. 1 to No. a and windboxes No. x+1 to No. y. The value of a is based on the following: the average CO concentration of the flue gas from windboxes No. 1 to No. a is not higher than the average CO concentration of the flue gas from windboxes No. (x+1) to No. y.

[0039] Preferably, the system further comprises a first heat exchange device 7. The fifth flue gas duct G5 is interconnected with the third flue gas duct G3 via the first heat exchange device 7.

[0040] Preferably, the system further comprises a denitration device 8. The first flue gas purification device 3 is an activated carbon desulfurization tower. The second flue gas purification device 5 is an activated carbon desulfurization and denitration tower. The denitration device 8 is optionally arranged on the third flue gas duct G3 or the fourth flue gas duct G4. Preferably, the system further comprises a second heat exchange device 9. The fourth flue gas duct G4 is interconnected with the third flue gas duct G3 through the second heat exchange device 9.

[0041] Preferably, the system further includes a denitrification device 8. Both the first flue gas purification device 3 and the second flue gas purification device 5 are activated carbon desulfurization devices. The flue gas outlet of the CO catalytic reactor 4 is connected to the flue gas inlet of the denitrification device 8 through the fourth flue gas duct G4. The flue gas outlet of the second flue gas purification device 5 is connected to the flue gas inlet of the denitrification device 8 through the sixth flue gas duct G6. The flue gas outlet of the denitrification device 8 is connected to the chimney 6 through the seventh flue gas duct G7. Preferably, the system further includes a second heat exchange device 9. The third flue gas duct G3 and the seventh flue gas duct G7 are interconnected through the second heat exchange device 9.

[0042] Preferably, the system further comprises a heating device 10. The heating device 10 is arranged at the flue gas outlet of the first flue gas purification device 3.

[0043] Preferably, the first flue L1, the second flue L2, the first flue gas duct G1, the third flue gas duct G3 and the fifth flue gas duct G5 are all provided with a temperature detection device and / or a CO concentration detection device.

[0044] Preferably, a dust collector 11 and an induced draft fan 12 are provided on the first flue gas duct G1 and / or the fifth flue gas duct G5.

[0045] Preferably, the water removal device 2 is a condensation water remover.

[0046] Example 1

[0047] A sintering flue gas CO removal system, the system comprises a sintering machine 1, a dehydration device 2, a first flue gas purification device 3, a CO catalytic reactor 4, a second flue gas purification device 5 and a chimney 6. According to the running direction of the sintering machine 1, the wind box below the sintering machine 1 is divided into a decarbonization wind box 101 and a non-decarbonization wind box 102. The decarbonization wind box 101 is connected to the first flue L1, and the non-decarbonization wind box 102 is connected to the second flue L2. The first flue L1 is connected to the flue gas inlet of the dehydration device 2 through the first flue gas pipe G1, the flue gas outlet of the dehydration device 2 is connected to the flue gas inlet of the first flue gas purification device 3 through the second flue gas pipe G2, the flue gas outlet of the first flue gas purification device 3 is connected to the flue gas inlet of the CO catalytic reactor 4 through the third flue gas pipe G3, and the flue gas outlet of the CO catalytic reactor 4 is connected to the chimney 6 through the fourth flue gas pipe G4. The second flue L2 is connected to the flue gas inlet of the second flue gas purification device 5 through the fifth flue gas pipe G5. The flue gas outlet of the second flue gas purification device 5 is connected to the chimney 6 through the sixth flue gas duct G6.

[0048] Example 2

[0049] Example 1 is repeated, except that the decarburization bellows 101 is the 1 / 3 bellows close to the head of the sintering machine, and the remaining bellows are non-decarburization bellows 102.

[0050] Example 3

[0051] Example 2 is repeated, except that the wind boxes under the sintering machine are numbered in sequence according to the running direction of the sintering machine, namely, wind boxes 1, ..., 18, ..., 29, the decarburization wind boxes 101 are wind boxes 1 to 18, and the non-decarburization wind boxes 102 are wind boxes 19 to 29. The value of x is based on the following: the SO2 concentration in the flue gas of wind boxes 1 to 18 is less than 250 mg / m 3 And the HCl concentration is less than 5 mg / m 3 .

[0052] Example 4

[0053] Example 3 is repeated, except that the decarbonization windboxes 101 are windboxes No. 3 to No. 18. The non-decarbonization windboxes 102 are windboxes No. 1 to No. 2 and windboxes No. 19 to No. 29. The value of a is based on the following: the average CO concentration of the flue gas from windboxes No. 1 to No. 2 is lower than the average CO concentration of the flue gas from windboxes No. 19 to No. 29.

[0054] Example 5

[0055] Example 4 is repeated, except that the system further comprises a first heat exchange device 7 . The fifth flue gas duct G5 is interconnected with the third flue gas duct G3 via the first heat exchange device 7 .

[0056] Example 6

[0057] Example 5 is repeated, except that the system further includes a denitrification device 8. The first flue gas purification device 3 is an activated carbon desulfurization tower. The second flue gas purification device 5 is an activated carbon desulfurization and denitrification tower. The denitrification device 8 is arranged on the third flue gas duct G3.

[0058] Example 7

[0059] Example 6 is repeated, except that the system further includes a second heat exchange device 9. The fourth flue gas duct G4 is interconnected with the third flue gas duct G3 via the second heat exchange device 9.

[0060] Example 8

[0061] Example 5 is repeated, except that the system also includes a denitrification device 8. The first flue gas purification device 3 and the second flue gas purification device 5 are both activated carbon desulfurization devices. The flue gas outlet of the CO catalytic reactor 4 is connected to the flue gas inlet of the denitrification device 8 through the fourth flue gas duct G4. The flue gas outlet of the second flue gas purification device 5 is connected to the flue gas inlet of the denitrification device 8 through the sixth flue gas duct G6. The flue gas outlet of the denitrification device 8 is connected to the chimney 6 through the seventh flue gas duct G7.

[0062] Example 9

[0063] Example 8 is repeated, except that the system further comprises a second heat exchange device 9. The third flue gas duct G3 and the seventh flue gas duct G7 are interconnected through the second heat exchange device 9.

[0064] Example 10

[0065] Example 7 is repeated, except that the system further comprises a heating device 10. The heating device 10 is arranged at the flue gas outlet of the first flue gas purification device 3.

[0066] Embodiment 11

[0067] Example 9 is repeated, except that the system further comprises a heating device 10. The heating device 10 is arranged at the flue gas outlet of the first flue gas purification device 3.

[0068] Example 12

[0069] Example 10 is repeated, except that the first flue L1, the second flue L2, the first flue gas duct G1, the third flue gas duct G3 and the fifth flue gas duct G5 are all provided with a temperature detection device and a CO concentration detection device.

[0070] Embodiment 13

[0071] Example 12 is repeated, except that the first flue gas duct G1 and the fifth flue gas duct G5 are provided with a dust collector 11 and an induced draft fan 12.

[0072] The dehydration device 2 is a condensation dehydrator.

Claims

1. A sintering flue gas CO removal system, characterized by: The system comprises a sintering machine (1), a dewatering device (2), a first flue gas purification device (3), a CO catalytic reactor (4), a second flue gas purification device (5) and a chimney (6); according to the running direction of the sintering machine (1), the wind box below the sintering machine (1) is divided into a decarburization wind box (101) and a non-decarburization wind box (102); the decarburization wind box (101) is connected to a first flue (L1), and the non-decarburization wind box (102) is connected to a second flue (L2); the first flue (L1) is connected to a flue gas inlet of the dewatering device (2) through a first flue gas pipeline (G1), and the dewatering device (2) is connected to a flue gas inlet of the second flue (L2). The flue gas outlet of the first flue gas purification device (3) is connected to the flue gas inlet of the first flue gas purification device (3) through a second flue gas duct (G2), the flue gas outlet of the first flue gas purification device (3) is connected to the flue gas inlet of the CO catalytic reactor (4) through a third flue gas duct (G3), and the flue gas outlet of the CO catalytic reactor (4) is connected to the chimney (6) through a fourth flue gas duct (G4); the second flue (L2) is connected to the flue gas inlet of the second flue gas purification device (5) through a fifth flue gas duct (G5); and the flue gas outlet of the second flue gas purification device (5) is connected to the chimney (6) through a sixth flue gas duct (G6).

2. The system according to claim 1, characterized in that: The decarburization bellows (101) are 1 / 3 to 2 / 3 of the bellows close to the head of the sintering machine, and the remaining bellows are non-decarburization bellows (102).

3. The system according to claim 2, characterized in that: According to the running direction of the sintering machine, the wind boxes under the sintering machine are numbered in sequence, namely, wind boxes 1, ..., x, ..., y, wherein the decarbonization wind boxes (101) are wind boxes No. 1 to No. x, and the non-decarbonization wind boxes (102) are wind boxes No. x+1 to No. y; wherein the value of x is based on the following: the SO2 concentration in the flue gas of wind boxes No. 1 to No. x is less than 250 mg / m 3 And the HCl concentration is less than 5 mg / m 3 .

4. The system according to claim 3, characterized in that: The SO2 concentration in the flue gas from the 1st to the xth wind box is less than 230mg / m 3 And the HCl concentration is less than 4 mg / m 3 .

5. The system according to claim 3, characterized in that: Assume that a is an integer greater than or equal to 1 and less than x, the decarbonization bellows (101) are bellows No. a+1 to No. x; the non-decarbonization bellows (102) are bellows No. 1 to No. a and bellows No. x+1 to No. y; wherein the value of a is based on the following: the average CO concentration of the flue gas from bellows No. 1 to No. a is not higher than the average CO concentration of the flue gas from bellows No. x+1 to No. y.

6. The system according to any one of claims 1 to 5, characterized in that: The system also includes a first heat exchange device (7); the fifth flue gas duct (G5) and the third flue gas duct (G3) are interconnected via the first heat exchange device (7).

7. The system according to any one of claims 1 to 5, characterized in that: The system also includes a denitrification device (8); the first flue gas purification device (3) is an activated carbon desulfurization tower; the second flue gas purification device (5) is an activated carbon desulfurization and denitrification tower; the denitrification device (8) is optionally arranged on the third flue gas duct (G3) or the fourth flue gas duct (G4).

8. The system according to any one of claims 1 to 5, characterized in that: The system further comprises a denitration device (8); the first flue gas purification device (3) and the second flue gas purification device (5) are both activated carbon desulfurization devices; the flue gas outlet of the CO catalytic reactor (4) is connected to the flue gas inlet of the denitration device (8) via a fourth flue gas duct (G4); the flue gas outlet of the second flue gas purification device (5) is connected to the flue gas inlet of the denitration device (8) via a sixth flue gas duct (G6); and the flue gas outlet of the denitration device (8) is connected to the chimney (6) via a seventh flue gas duct (G7).

9. The system according to claim 7, characterized in that: The system also includes a second heat exchange device (9); the fourth flue gas duct (G4) and the third flue gas duct (G3) are interconnected via the second heat exchange device (9).

10. The system according to claim 8, characterized in that: The system also includes a second heat exchange device (9); the third flue gas duct (G3) and the seventh flue gas duct (G7) are interconnected via the second heat exchange device (9).

11. The system according to any one of claims 1-5, 9-10, characterized in that: The system also includes a heating device (10); the heating device (10) is arranged at the flue gas outlet of the first flue gas purification device (3).

12. The system according to claim 6, characterized in that: The system also includes a heating device (10); the heating device (10) is arranged at the flue gas outlet of the first flue gas purification device (3).

13. The system according to claim 7, characterized in that: The system also includes a heating device (10); the heating device (10) is arranged at the flue gas outlet of the first flue gas purification device (3).

14. The system according to claim 8, characterized in that: The system also includes a heating device (10); the heating device (10) is arranged at the flue gas outlet of the first flue gas purification device (3).

15. The system according to claim 11, characterized in that: The first flue (L1), the second flue (L2), the first flue gas duct (G1), the third flue gas duct (G3) and the fifth flue gas duct (G5) are all provided with a temperature detection device and / or a CO concentration detection device.

16. The system according to any one of claims 12 to 14, characterized in that: The first flue (L1), the second flue (L2), the first flue gas duct (G1), the third flue gas duct (G3) and the fifth flue gas duct (G5) are all provided with a temperature detection device and / or a CO concentration detection device.

17. The system according to any one of claims 1-5, 9-10, 12-15, characterized in that: The first flue gas duct (G1) and / or the fifth flue gas duct (G5) are provided with a dust collector (11) and an induced draft fan (12); and / or The dewatering device (2) is a condensation dewatering device.

18. The system according to claim 6, characterized in that: The first flue gas duct (G1) and / or the fifth flue gas duct (G5) are provided with a dust collector (11) and an induced draft fan (12); and / or The dewatering device (2) is a condensation dewatering device.

19. The system according to claim 7, characterized in that: The first flue gas duct (G1) and / or the fifth flue gas duct (G5) are provided with a dust collector (11) and an induced draft fan (12); and / or The dewatering device (2) is a condensation dewatering device.

20. The system according to claim 8, characterized in that: The first flue gas duct (G1) and / or the fifth flue gas duct (G5) are provided with a dust collector (11) and an induced draft fan (12); and / or The dewatering device (2) is a condensation dewatering device.

21. The system according to claim 11, characterized in that: The first flue gas duct (G1) and / or the fifth flue gas duct (G5) are provided with a dust collector (11) and an induced draft fan (12); and / or The dewatering device (2) is a condensation dewatering device.

22. The system according to claim 16, characterized in that: The first flue gas duct (G1) and / or the fifth flue gas duct (G5) are provided with a dust collector (11) and an induced draft fan (12); and / or The dewatering device (2) is a condensation dewatering device.

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