A flue gas circulation denitrification sintering system and sintering method thereof

Abstract

The present invention discloses a flue gas circulation denitration sintering system and a sintering method thereof. The flue gas circulation denitration sintering system comprises a sintering machine, a first flue gas hood, a first fan, a denitration pipeline and a reducing gas pipeline. The sintering machine is divided into a sintering section and a denitration section in sequence along the traveling direction of the trolley. The sintering section is provided with a plurality of first wind boxes in sequence and at intervals along its length direction below the trolley. The bottoms of the plurality of first wind boxes respectively have outlets. The outlets of the plurality of first wind boxes are all connected to one end of the denitration pipeline. The other end of the denitration pipeline is connected to one end of the reducing gas pipeline through a first tee. The remaining interface of the first tee is connected to the air inlet of the first fan. The air outlet of the first fan is connected to the air inlet of the first flue gas hood. The first flue gas hood is arranged above the denitration section. The reducing gas pipeline is used to introduce reducing gas into the denitration pipeline. The sintering system and the sintering method thereof of the present invention have simple processes, realize partial denitration of sintering flue gas without consuming denitration catalyst, and save costs.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas denitration, and in particular to a flue gas circulating denitration sintering system and a sintering method thereof. Background Art

[0002] The steel industry is one of the major pollutants in the industrial field. Sintering is one of the most polluting processes in the steel production process. The particulate matter, SO2, NOx and dioxin emissions in its flue gas account for about 20%, 60%, 50% and 90% of the total emissions from steel production, respectively. It can be seen that the comprehensive treatment of flue gas pollutants in the sintering process has become a top priority for steel companies to meet environmental protection standards.

[0003] Compared with coal-fired flue gas from power plants, sintering flue gas from the steel industry has the characteristics of low temperature, large flue gas volume, large fluctuation range and unstable SO2 and NOx content. The characteristics of sintering flue gas from the steel industry have increased the difficulty of treating sintering flue gas to a certain extent. When treating sintering flue gas, it is necessary to comprehensively consider the characteristics of sintering flue gas from the steel industry itself and develop methods suitable for sintering flue gas treatment.

[0004] The sintering flue gas denitrification process started later than the desulfurization process. Currently, the more reliable processes mainly include: ① activated carbon adsorption process: the activated carbon adsorption process has been applied to the purification of sintering flue gas in large steel companies such as Nippon Steel, JFE, Posco and TISCO, and has achieved good results. However, the activated carbon adsorption process has high operating costs, large and expensive equipment, prominent corrosion problems, and high energy consumption for activated carbon regeneration. ② SCR catalytic method: The SCR catalytic method has a denitrification rate of more than 80%, but due to the low temperature of the sintering flue gas, a heating device is required, and expensive catalysts are consumed. The catalyst is easily poisoned and deactivated, which weakens the effect of SCR catalytic NOx reduction. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a flue gas denitration sintering system and a sintering method thereof without using a denitration agent, and the technical solution adopted is:

[0006] A flue gas circulation denitration sintering system comprises a sintering machine, a first flue gas hood, a first fan, a denitration pipeline and a reducing gas pipeline, wherein the sintering machine comprises a sintering machine body and an extension section arranged at the rear end of the sintering machine body, the length of the extension section is 10%-25% of the length of the sintering machine body, the sintering machine body is the sintering section of the sintering machine, the extension section is the denitration section of the sintering machine, the sintering section of the sintering machine is provided with a plurality of first wind boxes spaced in sequence along its length direction below a trolley, each of the first wind boxes has an outlet at the bottom, the outlets of the plurality of first wind boxes are respectively connected to one end of the denitration pipeline, the other end of the denitration pipeline is connected to one end of the reducing gas pipeline through a first tee, the remaining interface of the first tee is connected to the air inlet of the first fan, the air outlet of the first fan is connected to the air inlet of the first flue gas hood, the first flue gas hood is arranged above the denitration section of the sintering machine, and the reducing gas pipeline is used to introduce reducing gas into the denitration pipeline.

[0007] Preferably, it also includes an electrostatic precipitator, a main exhaust fan, a desulfurization and denitrification device, a chimney and an exhaust gas duct. The sintering section is divided into a first sintering section and a second sintering section in sequence along the traveling direction of the trolley. The length of the first sintering section is 30%-50% of the length of the sintering machine body. A plurality of first bellows are arranged in the first sintering section. The second sintering section is provided with a plurality of second bellows in sequence below the trolley along its length direction. The lower end of each second bellows has an opening, and the outlets of the plurality of second bellows are connected to one end of the exhaust gas duct, and the other end of the exhaust gas duct is connected to the air inlet of the electrostatic precipitator, the air outlet of the electrostatic precipitator is connected to the air inlet of the main exhaust fan, the air outlet of the main exhaust fan is connected to the air inlet of the desulfurization and denitrification device, the air outlet of the desulfurization and denitrification device is connected to the air inlet of the chimney, and the air outlet of the chimney is connected to the outside.

[0008] Preferably, the reducing gas is ammonia.

[0009] Preferably, it also includes a second fume hood, a second fan, a circulation duct and a combustion-supporting gas duct. The denitrification section of the sintering machine is provided with a plurality of third wind boxes spaced in sequence along its length direction below the trolley. The lower ends of the plurality of third wind boxes respectively have outlets, and the outlets of the plurality of third wind boxes are connected with one end of the circulation duct. The other end of the circulation duct and the other end of the combustion-supporting gas duct are connected through a second tee. The remaining interface of the second tee is connected with the air inlet of the second fan, and the air outlet of the second fan is connected with the air inlet of the second fume hood. The second fume hood is arranged above the sintering section of the sintering machine, and the combustion-supporting gas duct is used to introduce combustion-supporting gas into the circulation duct.

[0010] Preferably, a ring cooler is further included, and the hot exhaust gas outlet of the ring cooler is connected to the circulation pipeline.

[0011] Preferably, the combustion-supporting gas is air or oxygen.

[0012] A sintering method based on the above-mentioned flue gas circulation denitrification sintering system, wherein the flue gas generated in the first sintering stage is mixed with the reducing gas to form denitrification flue gas, and the denitrification flue gas is made to flow into the denitrification stage, and the flue gas generated in the second sintering stage is made to flow through the electrostatic precipitator and the desulfurization and denitrification device and then be discharged through the chimney.

[0013] Preferably, the method further comprises mixing the flue gas generated by the denitration section with the hot exhaust gas of the ring cooler and air or oxygen to form a circulating gas, and allowing the circulating gas to flow into the sintering section of the sintering machine.

[0014] Preferably, the volume ratio of reducing gas to NOx in the denitrification flue gas is 1:0.3-1.2.

[0015] Preferably, the volume concentration of oxygen in the circulating gas is 14%-20%.

[0016] The beneficial effects of the beneficial sintering system and sintering method of the present invention are:

[0017] The present invention circulates the reducing gas and the sintering flue gas with a high concentration of NOx to the denitration section. Since the temperature in the sintering material layer is relatively high, which can reach 800-1100°C, the temperature requirement of the catalytic reduction reaction of nitrogen oxides can be fully met within the temperature range of 800-1100°C. When denitrifying the sintering flue gas, no additional heating equipment for heating the flue gas is required. At the same time, the sintered ore has a component that acts as a reducing catalyst. The high-temperature sintered ore can meet the demand for the denitration catalyst, and there is no need to purchase a denitration catalyst externally, thereby effectively catalytically reducing the NOx generated during the sintering process, realizing partial denitration of the sintering flue gas. The process is simple, no denitration catalyst is consumed, the investment cost of the denitration process can be saved, and the denitration operation cost of the sintering process is reduced;

[0018] The temperature of the denitrification flue gas is within the range of 30-100° C. The present invention introduces the denitrification flue gas at 30-100° C. into the sintering material layer of the denitrification stage, and heat-treats the sintered ore in the sintering machine to slow down the cooling speed of the sintered ore, thereby effectively improving the quality of the sintered ore.

[0019] The low-temperature denitrification flue gas from the sintering section is circulated to the denitrification section. Under the high temperature conditions in the sintering material layer, the dioxins in the denitrification flue gas can be effectively decomposed, reducing the emission of dioxin-like substances, which is beneficial to environmental protection.

[0020] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 This is a schematic structural diagram of the flue gas circulation denitration sintering system according to Example 1 of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of the flue gas circulation denitrification sintering system described in Example 2 of the present invention.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] The following is combined with Figure 1 The principles and features of the present invention are described, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. In the following paragraphs, the present invention is described in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0027] Example 1

[0028] Reference Figure 1, an embodiment of the present invention is proposed, the flue gas circulation denitration sintering system in this embodiment comprises a sintering machine 1, a first flue gas hood 2, a first fan 3, a denitration pipeline 4 and a reducing gas pipeline 5, the sintering machine 1 comprises a sintering machine body and an extension section arranged at the tail end of the sintering machine body, the length of the extension section is 10%-25% of the length of the sintering machine body, the sintering machine body is the sintering section of the sintering machine 1, the sintering section is the part from the ignition point to the end of sintering of the sintering machine, the extension section is the denitration section of the sintering machine 1, the denitration section refers to the part from the end of sintering of the sintering machine to the tail end of the sintering machine, the trolley of the sintering machine moves from the head end of the sintering machine body To the tail end of the sintering machine 1, the sintering section of the sintering machine 1 is provided with a plurality of first wind boxes 6 spaced in sequence along its length direction below the trolley, and each of the first wind boxes 6 has an outlet at the bottom, and the outlets of the plurality of first wind boxes 6 are respectively connected with one end of the denitration pipe 4, and the other end of the denitration pipe 4 is connected with one end of the reducing gas pipe 5 through a first tee, and the remaining interface of the first tee is connected with the air inlet of the first fan 3, and the air outlet of the first fan 3 is connected with the air inlet of the first fume hood 2, and the first fume hood 2 is arranged above the denitration section of the sintering machine, and the reducing gas pipe 5 is used to introduce reducing gas into the denitration pipe 4.

[0029] Reducing gas is introduced into the denitrification pipeline 4, and the flue gas generated in the sintering section is drawn into the denitrification pipeline 4 under the action of the first fan 3 and mixed with the reducing gas to form denitrification flue gas. The denitrification flue gas flows into the denitrification section, and NOx, reducing gas and oxygen in the denitrification flue gas undergo oxidation-reduction reaction under the heating and catalytic action of the high-temperature sintered ore, thereby performing partial denitrification.

[0030] The NO in the denitrification flue gas x The reducing gas and O2 undergo redox reaction under the heating and catalytic action of the high-temperature sintered ore to perform partial denitration, and the dioxins in the denitrified flue gas are also partially decomposed and removed in the high-temperature sintered material layer; the temperature of the denitrified flue gas is 30-100°C, and the denitrified flue gas is passed into the sintered material layer of the denitrification section of the sintering machine 1, and the sintered ore is heat-treated on the sintering machine 1 to slow down the cooling rate of the sintered ore, which can effectively improve the quality of the sintered ore.

[0031] Preferably, it also includes an electrostatic precipitator 7, a main exhaust fan 8, a desulfurization and denitrification device 9, a chimney 10 and an exhaust gas duct 11. The sintering section is divided into a first sintering section and a second sintering section in sequence along the traveling direction of the trolley. The length of the first sintering section is 30%-50% of the length of the sintering machine 1 body. A plurality of first wind boxes 6 are arranged in the first sintering section. The second sintering section is provided with a plurality of second wind boxes 61 in sequence below the trolley along its length direction. The lower end of each second wind box 61 has an opening, and the outlets of the plurality of second wind boxes 61 are connected to one end of the exhaust gas duct 11. The other end of the exhaust gas duct 11 is connected to the air inlet of the electrostatic precipitator 7, the air outlet of the electrostatic precipitator 7 is connected to the air inlet of the main exhaust fan 8, the air outlet of the main exhaust fan 8 is connected to the air inlet of the desulfurization and denitrification device 9, the air outlet of the desulfurization and denitrification device 9 is connected to the air inlet of the chimney 10, and the air outlet of the chimney 10 is connected to the outside.

[0032] The NOx concentration in the flue gas of the first sintering section is higher than the NOx concentration in the flue gas of the second sintering section. The flue gas generated by the first sintering section is circulated to the denitrification section to reduce the volume of the sintering flue gas flowing into the denitrification section and increase the NOx concentration flowing into the denitrification section, which is beneficial to accelerate the catalytic reduction reaction rate of NOx. The NOx concentration in the flue gas generated by the first sintering section is relatively low. The flue gas in the second sintering section is introduced into the desulfurization and denitrification device 9 after dust removal. The remaining NOx and SO2 in the sintering flue gas are removed in the desulfurization and denitrification device 9, and the sintering flue gas after desulfurization and denitrification is discharged through the chimney 10.

[0033] Preferably, the reducing gas is ammonia.

[0034] The reaction products of NOx, ammonia and oxygen undergoing redox reaction under the heating and catalytic action of high-temperature sintered ore are pollution-free.

[0035] Preferably, it also includes a second fume hood 12, a second fan 13, a circulation duct 14 and a combustion-supporting gas duct 15. The denitrification section of the sintering machine is provided with a plurality of third wind boxes 62 spaced in sequence along its length direction below the trolley. The lower ends of the plurality of third wind boxes 62 respectively have outlets, and the outlets of the plurality of third wind boxes 62 are all connected with one end of the circulation duct 14. The other end of the circulation duct 14 and the other end of the combustion-supporting gas duct 15 are connected through a second tee. The remaining interface of the second tee is connected with the air inlet of the second fan 13. The air outlet of the second fan 13 is connected with the air inlet of the second fume hood 12. The second fume hood 12 is arranged above the sintering section of the sintering machine. The combustion-supporting gas duct 15 is used to introduce combustion-supporting gas into the circulation duct 14.

[0036] The flue gas with higher temperature in the denitrification section is circulated to the sintering section to assist the hot air sintering in the sintering section and fully utilize the waste heat and combustible component carbon monoxide in the flue gas in the denitrification section, thereby reducing the energy consumption of the process and improving the quality of sintered ore and sintering efficiency. At the same time, the remaining reducing gas in the circulating gas undergoes catalytic reduction reaction with NOx in the high-temperature sintering ore zone in the sintering material layer of the sintering section to carry out partial denitrification.

[0037] Preferably, a ring cooler 16 is further included, and a hot exhaust gas outlet of the ring cooler 16 is connected to the circulation pipeline 14 .

[0038] The circulation pipeline 14 is provided with a third tee, and the hot exhaust gas outlet of the ring cooler 16 is connected to the remaining interface of the third tee.

[0039] The hot exhaust gas discharged by the annular cooler 16 has a high temperature. The exhaust gas discharged by the annular cooler 16 exchanges heat with the circulating gas and flows into the first sintering section, thereby increasing the temperature of the circulating gas. The high-temperature circulating gas is then introduced into the sintering material layer in the first sintering section to achieve hot air sintering, thereby making full use of the waste heat and combustible components of the high-temperature sintered ore, saving energy, improving the quality of the sintered ore and the sintering efficiency, and recycling the waste heat of the sintered ore to improve the energy utilization rate of the sintering system.

[0040] Preferably, the combustion-supporting gas is air.

[0041] The air source is wide and the cost is low.

[0042] The combustion-supporting gas introduced into the circulation pipe 14 may also be oxygen.

[0043] Based on the above-mentioned flue gas circulation denitrification sintering system, a sintering method of the flue gas circulation denitrification sintering system is proposed, the method comprises: mixing the flue gas generated in the first sintering stage with the reducing gas to form denitrification flue gas, and making the denitrification flue gas flow into the denitrification stage, and making the flue gas generated in the second sintering stage flow through the electrostatic precipitator 7 and the desulfurization and denitrification device and then be discharged through the chimney.

[0044] The sintering method of the present invention causes NOx, reducing gas and O2 in the denitrification flue gas to undergo oxidation-reduction reactions under the heating and catalytic action of high-temperature sintered ore, thereby performing partial denitrification and achieving the removal of dioxins in the denitrification flue gas; the temperature of the denitrification flue gas is within the range of 30 to 100° C. The denitrification flue gas introduced into the sintering material layer of the denitrification section is used to heat treat the sintered ore, thereby slowing down the cooling rate of the sintered ore and effectively improving the quality of the sintered ore.

[0045] Preferably, the sintering method of the flue gas circulation denitrification sintering system of the present invention also includes mixing the flue gas generated by the denitrification section with the hot exhaust gas of the ring cooler and air or oxygen to form a circulating gas, and allowing the circulating gas to flow into the sintering section of the sintering machine.

[0046] The remaining reducing gas and NOx in the circulating gas undergo catalytic reduction reaction again in the sintering material layer of the sintering layer to carry out partial denitrification.

[0047] The volume ratio of the reducing gas to NOx in the denitrification flue gas is 1:0.3-1.2.

[0048] Among them, the reducing gas is ammonia. When the volume ratio of ammonia to NOx is 1:0.3-1.2, sufficient reducing agent is provided for the catalytic reduction reaction of NOx to ensure sufficient denitrification of the denitrification flue gas. At the same time, excess reducing gas provides sufficient reducing agent for the catalytic reduction reaction of NOx occurring in the sintering material layer in the subsequent circulating gas in the first sintering section.

[0049] Preferably, the volume concentration of oxygen in the circulating gas is 14%-20%.

[0050] The combustion-supporting gas is oxygen, which provides sufficient sintering raw materials for the hot air sintering of the sintering material layer in the sintering section.

[0051] Example 2

[0052] Different from Example 1, Figure 2 As shown, it also includes a first dust collector and a second dust collector, the air inlet of the first dust collector is connected to one end of the denitrification pipeline 4, the air outlet of the first dust collector is connected to one of the interfaces of the first tee, and the remaining two interfaces of the first tee are respectively connected to the air inlet of the first fan and one end of the reducing gas pipeline; the hot exhaust gas outlet of the ring cooler 16 and the circulating pipeline 14 are respectively connected to the air inlet of the second dust collector, the air outlet of the second dust collector is connected to one of the interfaces of the second tee, and the remaining two air outlets of the second tee are respectively connected to the air inlet of the second fan 13 and one end of the combustion-supporting gas pipeline 15.

[0053] The first dust collector is used to remove dust from the flue gas of the first sintering section, and the first dust collector can prevent the dust in the flue gas of the first sintering section from damaging the first fan 3; the second dust collector can remove dust from the flue gas of the denitrification section and the hot exhaust gas of the ring cooler 16 to prevent dust from circulating in the sintering system and damaging the second fan 13.

[0054] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A flue gas circulation denitrification sintering system, characterized in that: The invention comprises a sintering machine (1), a first fume hood (2), a first fan (3), a denitration pipeline (4), a reducing gas pipeline (5) and an exhaust gas pipeline (11). The sintering machine (1) comprises a sintering machine body and an extension section arranged at the rear end of the sintering machine body, the length of the extension section being 10%-25% of the length of the sintering machine body, the sintering machine body being the sintering section of the sintering machine (1), the extension section being the denitration section of the sintering machine (1), the sintering section of the sintering machine (1) being provided with a plurality of first wind boxes (6) arranged in sequence along the length direction below the trolley, each of the first wind boxes (6) having an outlet at the bottom, the outlets of the plurality of first wind boxes (6) being respectively connected to one end of the denitration pipeline (4), the other end of the denitration pipeline (4) being connected to one end of the reducing gas pipeline (5) via a first tee, the first tee having a plurality of outlets arranged at the bottom of the trolley. The lower interface is connected to the air inlet of the first fan (3), the air outlet of the first fan (3) is connected to the air inlet of the first fume hood (2), the first fume hood (2) is arranged above the denitration section of the sintering machine, and the reducing gas pipeline (5) is used to introduce reducing gas into the denitration pipeline (4); the sintering section is divided into a first sintering section and a second sintering section in sequence along the moving direction of the trolley, the length of the first sintering section is 30%-50% of the length of the sintering machine body, a plurality of the first wind boxes (6) are arranged in the first sintering section, and the second sintering section is provided with a plurality of second wind boxes (61) in sequence below the trolley along its length direction, each of the second wind boxes (61) has an opening at the lower end, and the outlets of the plurality of second wind boxes (61) are all connected to one end of the exhaust pipe (11); the reducing gas is ammonia.

2. The flue gas circulation denitration sintering system according to claim 1 is characterized in that: The exhaust gas system further comprises an electrostatic precipitator (7), a main exhaust fan (8), a desulfurization and denitration device (9) and a chimney (10); the other end of the exhaust gas pipeline (11) is connected to the air inlet of the electrostatic precipitator (7); the air outlet of the electrostatic precipitator (7) is connected to the air inlet of the main exhaust fan (8); the air outlet of the main exhaust fan (8) is connected to the air inlet of the desulfurization and denitration device (9); the air outlet of the desulfurization and denitration device (9) is connected to the air inlet of the chimney (10); and the air outlet of the chimney (10) is connected to the outside.

3. The flue gas circulation denitration sintering system according to claim 1 or 2, characterized in that: The invention also comprises a second fume hood (12), a second fan (13), a circulation duct (14) and a combustion-supporting gas duct (15); a plurality of third wind boxes (62) are sequentially arranged at intervals along the length direction of the denitration section of the sintering machine below the trolley; the lower ends of the plurality of third wind boxes (62) respectively have outlets; the outlets of the plurality of third wind boxes (62) are all connected to one end of the circulation duct (14); the other end of the circulation duct (14) and the other end of the combustion-supporting gas duct (15) are connected via a second tee; the remaining interface of the second tee is connected to the air inlet of the second fan (13); the air outlet of the second fan (13) is connected to the air inlet of the second fume hood (12); the second fume hood (12) is arranged above the sintering section of the sintering machine; and the combustion-supporting gas duct (15) is used to introduce the combustion-supporting gas into the circulation duct (14).

4. The flue gas circulation denitration sintering system according to claim 3 is characterized in that: It also includes a ring cooler (16), wherein a hot exhaust gas outlet of the ring cooler (16) is in communication with the circulation pipeline (14).

5. The flue gas circulation denitration sintering system according to claim 3 is characterized in that: The combustion-supporting gas is air or oxygen.

6. A sintering method based on the flue gas circulation denitration sintering system according to any one of claims 2 to 5, characterized in that: The flue gas generated in the first sintering stage is mixed with the reducing gas to form denitrification flue gas, and the denitrification flue gas is made to flow into the denitrification stage, and the flue gas generated in the second sintering stage flows through the electrostatic precipitator, the desulfurization and denitrification device and is discharged through the chimney.

7. The sintering method of the flue gas circulation denitration sintering system according to claim 6, characterized in that: The method also includes mixing the flue gas generated by the denitration section with the hot exhaust gas from the ring cooler and air or oxygen to form a circulating gas, and allowing the circulating gas to flow into the sintering section of the sintering machine.

8. The sintering method of the flue gas circulation denitration sintering system according to claim 7, characterized in that: The volume ratio of the reducing gas to NOx in the denitrification flue gas is 1:0.3-1.

2.

9. The sintering method of the flue gas circulation denitration sintering system according to claim 7, characterized in that: The volume concentration of oxygen in the circulating gas is 14%-20%.

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