Coke oven flue gas purification system

Abstract

The utility model relates to the technical field of coke oven flue gas purification, in particular to a coke oven flue gas purification system which comprises a primary heat exchange device, a secondary heat exchange device, a desulfurization device, a denitration device, a heating device and a dust removal device, the first-stage heat exchange device is connected with the second-stage heat exchange device, the desulfurization device is connected with the first-stage heat exchange device, the denitration device is connected with the second-stage heat exchange device, and the dust removal device is used for removing particulate matters in coke oven flue gas after desulfurization and before denitration at the same time; the desulfurization process and the denitration process are combined through the matching effect of all the components, so that waste heat generated in the coke oven flue gas treatment process is fully circulated in the system, the waste heat is utilized in a gradient mode through the first-stage heat exchange device and the second-stage heat exchange device, and the whole treatment process is more energy-saving, efficient and environmentally friendly; and the whole system is prevented from being blocked through one dust removal device, so that the whole system is simpler and more convenient to set.

Description

Technical Field

[0001] The utility model relates to the technical field of coke oven fume purification, in particular to a coke oven fume purification system. Background Art

[0002] The coking process is the link with the highest pollutant emissions in the steel industry. It produces a large amount of coke oven flue gas, which has a high concentration of pollutants, including sulfur dioxide, which is usually 140-500 mg / Nm 3 The concentration of nitrogen oxides is usually between 350-700 mg / Nm 3 Especially when coke oven gas is used as coking fuel, nitrogen oxides can reach as high as 1000 mg / Nm 3 In order to meet today's increasingly stringent emission requirements and avoid serious environmental pollution, the coke oven flue gas must be desulfurized and denitrified before it can be discharged.

[0003] Existing desulfurization methods usually include wet desulfurization, dry desulfurization and semi-dry desulfurization. Among them, semi-dry desulfurization is one of the most widely used and efficient desulfurization methods. Semi-dry desulfurization technologies mainly include circulating fluidized bed (CFB) and rotary spray method (SDA). Existing denitrification methods usually include selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR). Among them, selective catalytic reduction is one of the most widely used denitrification technologies due to its good denitrification effect and low ammonia leakage rate.

[0004] In the coking process, in order to ensure that the coke oven is always in normal operation, it is necessary to ensure that the chimney is always in hot standby state, that is, after the desulfurization and denitrification are completed, the flue gas discharged still needs to be maintained above 120°C. In addition, when semi-dry desulfurization is adopted, the flue gas needs to be controlled at about 130-150°C. When selective catalytic reduction is used for denitrification, the flue gas needs to be controlled above 230°C, usually between 230-250°C. Therefore, in the prior art, as long as the coke oven flue gas needs to be desulfurized and denitrified at the same time, there will be a problem of temperature window mismatch. In order to achieve the best reaction efficiency, a large amount of additional energy is usually consumed to meet the temperature window in the process, which increases the operating cost and is contrary to the concept of flue gas treatment of reducing pollution and carbon emissions, energy saving and high efficiency. In addition, when selective catalytic reduction is used for denitrification, the coke oven flue gas needs to be dedusted, and since particulate matter will be produced in the coke oven flue gas after desulfurization, dust removal is also required. Therefore, in the conventional coke oven flue gas treatment process, at least two dust collectors are often required to repeatedly dedust the coke oven flue gas, which has great difficulty and cost in setting up.

[0005] Therefore, the present application proposes a coke oven flue gas purification system, which controls the temperature of the coke oven flue gas entering or leaving the desulfurization process and the denitrification process respectively through two heat exchange devices, and directly performs denitrification treatment on the coke oven flue gas after desulfurization and heating, and utilizes the waste heat of the coke oven flue gas in a step-by-step manner, so that the waste heat of the flue gas circulates internally in the coke oven flue gas treatment system, meeting the temperature window required for desulfurization and then denitrification, reducing operating costs and energy consumption, and adapting to temperature fluctuations and operating condition changes during the coke oven flue gas treatment process; and arranging a dust removal device between the desulfurization device and the denitrification device, so that only one dust removal device is needed to prevent equipment blockage in the entire coke oven flue gas treatment process, making the entire coke oven flue gas treatment process more efficient and energy-saving while being simpler. Utility Model Content

[0006] To achieve the above objectives, the utility model is implemented through the following technical solutions: The utility model provides a coke oven flue gas purification system, including: a primary heat exchange device, a secondary heat exchange device, a desulfurization device, a denitrification device and a dust removal device;

[0007] The primary heat exchange device and the secondary heat exchange device both have a temperature rising section and a temperature falling section that can perform heat exchange with each other;

[0008] The air outlet of the temperature rising section of the first-stage heat exchange device is connected to the air inlet of the temperature rising section of the second-stage heat exchange device;

[0009] The air inlet of the desulfurization device is connected to the air outlet of the temperature-lowering section of the primary heat exchange device, and the air outlet of the desulfurization device is connected to the air inlet of the temperature-raising section of the primary heat exchange device;

[0010] The air inlet of the denitration device is communicated with the air outlet of the temperature-increasing section of the secondary heat exchange device, and the air outlet of the denitration device is communicated with the air inlet of the temperature-increasing section of the secondary heat exchange device;

[0011] The dust removal device is arranged between the air inlet of the denitration device and the air outlet of the desulfurization device.

[0012] Preferably, the cooling section of the primary heat exchange device is used to cool the coke oven flue gas from 180-200°C to between 130-150°C, and the heating section of the primary heat exchange device is used to heat the coke oven flue gas desulfurized by the desulfurization device to between 160-180°C;

[0013] And / or; the heating section of the secondary heat exchange device is used to heat the coke oven flue gas passing through the heating section of the primary heat exchange device to between 200-220°C, and the cooling section of the secondary heat exchange device is used to cool the coke oven flue gas passing through the denitrification device to between 170-190°C.

[0014] Preferably, the coke oven flue gas purification system also includes a heating device, which is arranged between the air inlet of the denitrification device and the air outlet of the heating section of the secondary heat exchange device, and the heating device is used to heat the coke oven flue gas passing through the heating section of the secondary heat exchange device to a temperature greater than 230°C.

[0015] Preferably, the coke oven flue gas purification system further comprises an ammonia injection device, and the ammonia injection device is arranged between the air inlet of the denitrification device and the heating device.

[0016] Preferably, the coke oven flue gas purification system further comprises a chimney, the chimney is connected to the gas outlet of the cooling section of the secondary heat exchange device, and the operating temperature of the chimney is greater than 120°C.

[0017] Preferably, the chimney is provided with an induced draft fan, and the induced draft fan is used to discharge the coke oven smoke in the chimney.

[0018] Preferably, the dust removal device is arranged between the air outlet of the desulfurization device and the air inlet of the temperature rising section of the primary heat exchange device.

[0019] Preferably, the desulfurization device comprises a desulfurization tower, wherein the desulfurization tower contains a desulfurizer slurry, and the desulfurizer slurry contacts the coke oven flue gas by spraying, and removes sulfides in the coke oven flue gas.

[0020] Preferably, the denitration device comprises a denitration tower, wherein a catalyst is provided in the denitration tower, and the catalyst is used to react the coke oven flue gas after ammonia is sprayed by the ammonia spraying device with ammonia, so as to remove nitrogen oxides.

[0021] Preferably, the primary heat exchange device and the secondary heat exchange device include shell and tube flue gas heat exchangers or rotary heat exchangers.

[0022] In the utility model, a coke oven flue gas purification system is provided, comprising a primary heat exchange device, a secondary heat exchange device, a desulfurization device, a denitrification device, a heating device and a dust removal device; the primary heat exchange device is connected to the secondary heat exchange device, the desulfurization device is connected to the primary heat exchange device, the denitrification device is connected to the secondary heat exchange device, and the dust removal device is used for removing particulate matter in the coke oven flue gas after desulfurization and before denitrification; through the cooperation of various components, the desulfurization and denitrification processes are combined, so that the waste heat generated during the treatment of the coke oven flue gas is fully circulated in the system, and the waste heat is cascaded through the primary heat exchange device and the secondary heat exchange device, so that the entire treatment process is more energy-efficient, efficient and environmentally friendly, and a dust removal device can avoid blockage of the entire system, making the entire system easier to set up. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 The utility model is a schematic diagram of a coke oven flue gas purification system.

[0025] The accompanying drawings are denoted as follows:

[0026] 1-primary heat exchange device; 2-secondary heat exchange device; 3-desulfurization device; 4-denitrification device; 5-dust removal device; 6-heating device; 7-ammonia injection device; 8-chimney; 1a-cooling section of the primary heat exchange device; 1b-warming section of the primary heat exchange device; 2a-warming section of the secondary heat exchange device; 2b-cooling section of the secondary heat exchange device. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] As used in the present invention, the singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", and the term "at least two" is generally used in a sense including "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features. The term "proximal end" is usually the end close to the operator, and the term "distal end" is usually the end close to the patient. "One end" and "the other end" as well as "proximal end" and "distal end" usually refer to two corresponding parts, which include not only the endpoints. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of the two elements or the interaction relationship between the two elements. In addition, as used in the present utility model, an element is arranged on another element, which usually only means that there is a connection, coupling, matching or transmission relationship between the two elements, and the connection, coupling, matching or transmission between the two elements can be direct or indirect through an intermediate element, and it cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element can be in any position such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0029] Please refer to Figure 1 As shown, a schematic diagram of the process structure of an embodiment of a coke oven flue gas purification system provided by the present application comprises: a primary heat exchange device 1, a secondary heat exchange device 2, a desulfurization device 3, a denitrification device 4 and a dust removal device 5; the primary heat exchange device 1 and the secondary heat exchange device 2 both have a heating section and a cooling section that can perform heat exchange with each other; the air outlet of the heating section 1b of the primary heat exchange device is connected to the air inlet of the heating section 2a of the secondary heat exchange device; the air inlet of the desulfurization device 3 is connected to the air outlet of the cooling section 1b of the primary heat exchange device, and the air outlet of the desulfurization device 3 is connected to the air inlet of the heating section 1b of the primary heat exchange device; the air inlet of the denitrification device 4 is connected to the air outlet of the heating section 2a of the secondary heat exchange device, and the air outlet of the denitrification device 4 is connected to the air inlet of the cooling section 2b of the secondary heat exchange device; the dust removal device 5 is arranged between the air inlet of the denitrification device 4 and the air outlet of the desulfurization device 3.

[0030] In this embodiment, the primary heat exchange device 1 and the secondary heat exchange device 2 are both shell and tube flue gas heat exchangers, which are also called tubular heat exchangers. The tubular heat exchanger has a heating section and a cooling section, and the heat obtained by the cooling section provides heat for heating the heating section to achieve internal circulation of heat, thereby achieving the technical effect of energy saving. In addition, conventional tubular heat exchangers can usually only heat liquids or gases with a temperature difference of 50°C or less. If the temperature difference is too high and excessive thermal stress is generated, the tubular heat exchanger may be damaged. Therefore, when heat is exchanged for liquids or gases with a large temperature difference, certain compensation measures need to be taken. The above are all existing technologies, and this application will not go into details here.

[0031] In other alternative embodiments, the primary heat exchange device 1 and the secondary heat exchange device 2 may also be rotary heat exchangers or other known gas heat exchangers, and the present application does not make too many limitations here.

[0032] In the present application, the desulfurization method adopted is the rotary spray method (SDA) in the semi-dry desulfurization technology, so the desulfurization device 3 includes a desulfurization tower, which is usually a cylindrical cast iron desulfurization tower, or a lying glass fiber reinforced plastic desulfurization reaction tower; the desulfurization tower usually has a reaction chamber, and in addition, the desulfurization tower also has a desulfurizer slurry, which contacts the coke oven flue gas in the reaction chamber by spraying, thereby increasing the contact area between the desulfurizer slurry and the coke oven flue gas, so as to more thoroughly remove the sulfides in the coke oven flue gas. The upper desulfurization device 3 adopts an existing desulfurization tower, which is a prior art and will not be repeated here.

[0033] In addition, the denitration method used in the present application is a selective catalytic reduction method (SCR), and the denitration device 4 includes a denitration tower, which is usually an SCR reactor, and can also be a gas-heated denitration tower. The denitration tower has a catalyst, and the catalyst mainly includes titanium dioxide (TiO2), vanadium pentoxide (V2O5), tungsten trioxide (WO3) and molybdenum oxide (MoO3). The catalyst is used to accelerate the reaction of the coke oven flue gas after ammonia injection by the ammonia injection device with ammonia, so as to reduce the nitrogen oxides in the coke oven flue gas to nitrogen and oxygen more quickly and thoroughly, thereby removing the nitrogen oxides in the coke oven flue gas. The denitration device 4 package adopts an existing denitration tower, which is a prior art, and the present application does not make too many restrictions and redundant descriptions here.

[0034] Please refer to Figure 1As shown, in the present application, a dust removal device 5 is provided between the air outlet of the desulfurization device 3 and the air inlet of the denitrification device 4. Specifically, the dust removal device 5 is provided between the air outlet of the desulfurization device 3 and the air inlet of the heating section 1b of the primary heat exchange device. The dust removal device 5 is used to filter the particulate matter in the coke oven flue gas after desulfurization by the desulfurization device 3, and prevent the particulate matter in the coke oven flue gas from entering the denitrification device 4, thereby causing the catalyst pipeline in the denitrification device 4 to be blocked.

[0035] In other alternative embodiments, the dust removal device 5 can also be arranged between the air outlet of the heating section 1b of the first-stage heat exchange device and the air inlet of the heating section 1a of the second-stage heat exchange device. The above setting methods can be implemented and should all fall within the protection scope of the present application. The present application does not make too many restrictions here.

[0036] It is worth noting that the dust removal device 5 can be a bag dust collector or an electrostatic precipitator, both of which are prior arts and the present application does not make too many limitations here.

[0037] In the present application, the cooling section 1a of the primary heat exchanger is used to cool the coke oven flue gas from 180-200°C to between 130-150°C, and the heating section 1b of the primary heat exchanger is used to heat the coke oven flue gas after desulfurization by the desulfurization device 3 to between 160-180°C; in addition, the heating section 2a of the secondary heat exchanger is used to heat the coke oven flue gas passing through the heating section 1b of the primary heat exchanger to between 200-220°C, and the cooling section 2b of the secondary heat exchanger is used to cool the coke oven flue gas passing through the denitrification device to between 170-190°C.

[0038] Among them, the initial temperature of the coke oven flue gas entering the cooling section 1a of the primary heat exchange device is relatively high, and the initial temperature of the coke oven flue gas entering the heating section 1b of the primary heat exchange device after desulfurization by the desulfurization device 3 is relatively low. Therefore, the coke oven flue gas entering the cooling section 1a of the primary heat exchange device and the coke oven flue gas entering the heating section 1b of the primary heat exchange device perform heat exchange, so that the temperature of the coke oven flue gas after passing through the cooling section 1a of the primary heat exchange device is reduced, and the temperature of the coke oven flue gas passing through the heating section 1b of the primary heat exchange device is increased.

[0039] In addition, the initial temperature of the coke oven flue gas entering the heating section 2a of the secondary heat exchange device is relatively low, and the initial temperature of the coke oven flue gas entering the cooling section 2b of the secondary heat exchange device after passing through the heating device 6 and the denitrification device 3 is relatively high. Therefore, the coke oven flue gas entering the heating section 2a of the secondary heat exchange device performs heat exchange with the coke oven flue gas entering the cooling section 2b of the secondary heat exchange device, so that the temperature of the coke oven flue gas after passing through the cooling section 2b of the secondary heat exchange device is reduced, and the temperature of the coke oven flue gas passing through the heating section 2a of the secondary heat exchange device is increased.

[0040] Through the above arrangement, it is no longer necessary to use additional gas or electrical energy to heat or cool the coke oven flue gas to meet the different temperature windows required in the desulfurization reaction and denitrification reaction.

[0041] It is worth noting that, during the use of the denitration device 4, the temperature of the coke oven flue gas required for its operation is relatively high, so a heating device 6 is provided between the heating section 2a of the secondary heat exchange device and the denitration device 4, and the heating device 6 is used to further heat the coke oven flue gas heated by the heating section 2a of the secondary heat exchange device to a temperature greater than 230°C, so that the denitration reaction in the denitration device 4 is more intense, thereby making the denitration effect more thorough. The heating device 6 can be an electric heater or a pipeline heater, all of which are prior arts, and this application does not make too many restrictions here.

[0042] Please refer to Figure 1 As shown, an ammonia spraying device 7 is further provided between the heating device 6 and the denitration device 3. The ammonia spraying device 7 has at least one reaction chamber and an injector. The ammonia spraying device 7 is used to spray ammonia water onto the high-temperature coke oven flue gas (greater than 230° C.), so that part of the nitrogen oxides in the coke oven flue gas is converted into nitrogen and water vapor to perform preliminary denitration treatment on the coke oven flue gas. The ammonia spraying device can be an SCR supporting ammonia equipment or an ammonia uniform injector. The above are all prior arts and this application does not make too many limitations here.

[0043] Please refer to Figure 1 As shown, in the present application, the coke oven flue gas purification system further includes a chimney 8, which is used to discharge the coke oven flue gas treated by the desulfurization device 3 and the denitrification device 4, and the chimney 8 is connected to the outlet of the cooling section 2b of the secondary heat exchange device, and receives the temperature of the gas discharged from the outlet of the cooling section 2b of the secondary heat exchange device between 170-190°C, and the chimney 8 is kept in a hot standby state, that is, the working temperature of the chimney 8 is above 120°C, so that the coke oven flue gas generates thermal buoyancy after entering the chimney 8 and is discharged upward from the chimney, in addition, the temperature difference between the chimney and the coke oven flue gas is too large to cause damage to the inner wall of the chimney 8. It is worth noting that there is an induced draft fan in the chimney 8, which is used to control the air flow direction in the chimney 8 and to discharge the coke oven flue gas in the chimney 8.

[0044] The following is a specific embodiment of the present application:

[0045] The coking plant of a steel mill produces 1.1 million tons of coke per year. The flue gas is discharged directly through the chimney without purification, which does not meet the ultra-low emission requirements. Therefore, a real-time desulfurization and denitrification ultra-low emission transformation project is carried out. The flue gas temperature treated by this project is about 200℃, and the SO2 concentration is >200mg / Nm 3 , NO x Concentration>500mg / Nm 3 , dust (i.e. particulate matter in the flue gas) concentration>30mg / Nm 3 Considering that the selected treatment process must have good adaptability to the fluctuation of coke oven working conditions, high treatment efficiency and stable disposal of by-products, and the exhaust temperature needs to be greater than 130°C to meet the thermal standby requirements of the chimney, it is determined that the desulfurization process adopts calcium-based SDA desulfurization, and the denitrification process adopts SCR denitrification, and desulfurization is carried out before denitrification. Combined with its specific flue gas characteristics, it is finally determined to apply the "rotary spray method (SDA) calcium-based desulfurization + selective catalytic reduction (SCR) denitrification" process route based on the cascade utilization of waste heat in this application to meet the optimal temperature reaction window required for desulfurization and denitrification. Finally, after the project was put into operation, the emission concentrations of various pollutants were: SO2≤30mg / Nm 3 , NO x ≤150mg / Nm 3 , dust ≤10mg / Nm 3 , meeting the emission standards.

[0046] In summary, in the present invention, a coke oven flue gas purification system is proposed, comprising a primary heat exchange device 1, a secondary heat exchange device 2, a desulfurization device 3, a denitrification device 4 and a dust removal device 5; the primary heat exchange device 1 and the secondary heat exchange device 2 both have a heating section and a cooling section, and through the cooperation of the primary heat exchange device 1 and the secondary heat exchange device 2, the coke oven flue gas is heated or cooled to a suitable temperature in the coke oven flue gas purification system according to different working conditions. In addition, the primary heat exchange device 1 and the secondary heat exchange device 2 stepwise utilize the waste heat generated by the circulation of the coke oven flue gas in the system, combining desulfurization and denitrification treatment into one system while meeting the different temperature windows required for desulfurization and denitrification, and the entire system only needs one dust removal device 5 to meet the requirements of the entire coke oven flue gas purification system for removing impurities such as particulate matter in the coke oven flue gas, preventing the denitrification device 4 from being blocked while avoiding the particulate matter and other impurities generated during the desulfurization process of the desulfurization device 3 from entering the chimney for discharge, and the layout of the entire system is simple, and the processing process is energy-saving and efficient.

[0047] Finally, it should be noted that the above is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A coke oven flue gas purification system, characterized in that: include: Primary heat exchange device, secondary heat exchange device, desulfurization device, denitrification device and dust removal device; The primary heat exchange device and the secondary heat exchange device both have a temperature rising section and a temperature falling section that can perform heat exchange with each other; The air outlet of the temperature rising section of the first-stage heat exchange device is connected to the air inlet of the temperature rising section of the second-stage heat exchange device; The air inlet of the desulfurization device is connected to the air outlet of the temperature-lowering section of the primary heat exchange device, and the air outlet of the desulfurization device is connected to the air inlet of the temperature-raising section of the primary heat exchange device; The air inlet of the denitration device is communicated with the air outlet of the temperature-increasing section of the secondary heat exchange device, and the air outlet of the denitration device is communicated with the air inlet of the temperature-reducing section of the secondary heat exchange device; The dust removal device is arranged between the air inlet of the denitration device and the air outlet of the desulfurization device.

2. A coke oven flue gas purification system according to claim 1, characterized in that: The coke oven flue gas purification system also includes a heating device, which is arranged between the air inlet of the denitrification device and the air outlet of the heating section of the secondary heat exchange device, and is used to heat the coke oven flue gas passing through the heating section of the secondary heat exchange device to a temperature greater than 230°C.

3. A coke oven flue gas purification system according to claim 2, characterized in that: The coke oven flue gas purification system further comprises an ammonia spraying device, which is arranged between the air inlet of the denitrification device and the heating device.

4. A coke oven flue gas purification system according to claim 1, characterized in that: The coke oven flue gas purification system further comprises a chimney, which is connected to the gas outlet of the cooling section of the secondary heat exchange device, and the operating temperature of the chimney is greater than 120°C.

5. A coke oven flue gas purification system according to claim 4, characterized in that: The chimney is provided with an induced draft fan, and the induced draft fan is used to discharge the coke oven smoke in the chimney.

6. A coke oven flue gas purification system according to claim 1, characterized in that: The dust removal device is arranged between the air outlet of the desulfurization device and the air inlet of the temperature rising section of the primary heat exchange device.

7. A coke oven flue gas purification system according to claim 1, characterized in that: The desulfurization device comprises a desulfurization tower, wherein the desulfurization tower contains desulfurizer slurry, and the desulfurizer slurry contacts the coke oven flue gas through spraying, and removes sulfides in the coke oven flue gas.

8. A coke oven flue gas purification system according to claim 3, characterized in that: The denitration device comprises a denitration tower, wherein a catalyst is arranged in the denitration tower, and the catalyst is used to make the coke oven flue gas sprayed with ammonia by the ammonia spraying device react with ammonia to remove nitrogen oxides.

9. A coke oven flue gas purification system according to claim 1, characterized in that: The primary heat exchange device and the secondary heat exchange device include shell and tube flue gas heat exchangers or rotary heat exchangers.

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