A denitration device system and denitration method for roasting flue gas in a chain grate-rotary kiln

Abstract

The present invention provides a denitrification device system and a denitrification method for roasting flue gas in a chain grate-rotary kiln. The denitrification device system includes a rotary kiln and a chain grate with a built-in denitrification agent injection device connected in sequence; the denitrification agent injection device is arranged in the second preheating section of the chain grate; with the ground as the horizontal plane, the denitrification agent injection device is arranged upwardly inclined; the second preheating section includes a smoke hood area, a reaction area and a material area from top to bottom; the second preheating section includes at least N denitrification sections, where N≥3; the denitrification device system of the present invention adjusts the position layout of the denitrification agent injection device in each denitrification section and sets the denitrification agent injection device to be inclined upward, so that the denitrification agent is evenly distributed in the flue gas, and the average residence time of the denitrification agent in the flue gas is preferably extended to more than 1.2s, so that the flue gas and the denitrification agent fully react, and the flue gas denitrification rate is preferably increased to more than 50%.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas treatment, and specifically relates to a denitration device system and a denitration method for flue gas roasted in a chain grate-rotary kiln, and more particularly to an SNCR denitration device system and a denitration method for flue gas roasted in a chain grate-rotary kiln. Background Art

[0002] At present, the pellet roasting processes mainly include vertical furnace roasting process, belt roasting machine process and chain grate-rotary kiln process. Among them, chain grate-rotary kiln has large production capacity, high heat utilization rate, low total energy consumption, and produces pellets with uniform quality and high strength, which is widely used. However, in the pellet production process, NO x The emission intensity is high, causing serious environmental pollution. Existing methods for treating flue gas from chain grate-rotary kilns include catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and ozone oxidation denitrification. Among them, the SCR method has a high denitrification efficiency, but its temperature window is generally between 320 and 400°C, making it difficult to use this technology directly in the high-temperature flue gas of the chain grate high-temperature preheating section (950 to 1100°C); the main working principle of the ozone oxidation denitrification method is to oxidize the almost water-insoluble NO in the flue gas into a high-valent NO that is more easily soluble in water. x , it can be removed by desulfurization equipment, but high temperature flue gas can easily make high-valent NO x Decomposition, and due to the NO in the pellet roasting flue gas in the grate-rotary kiln x If the concentration is high, using ozone oxidation denitrification method to treat it will also result in high operating costs.

[0003] However, since the reaction temperature range of the SNCR method (900-1100°C) is consistent with the temperature distribution of the high-temperature preheating section of the chain grate, denitrification of the flue gas during the preheating of the pellet material can effectively reduce the energy consumption of denitrification operation; however, in actual operation, the SNCR reaction zone has shortcomings such as uneven flue gas distribution, uneven mixing of denitrifier and flue gas, and short reaction residence time, resulting in low denitrification efficiency in the SNCR reaction zone, heavy subsequent processing load, and difficulty in meeting flue gas emission requirements.

[0004] CN108392984A discloses a chain grate rotary kiln denitration system and a denitration method. The denitration system includes a chain grate, a rotary kiln and an annular cooler connected in sequence. The chain grate includes a blast drying section, an exhaust drying section, a first preheating section and a second preheating section connected in sequence. The denitration system also includes a denitration reactor. The second preheating section has a flue gas outlet, and the exhaust drying section has a flue gas inlet. The denitration reactor is connected between the flue gas outlet of the second preheating section and the flue gas inlet of the exhaust drying section. A reducing agent injection device is also connected between the denitration reactor and the flue gas outlet of the second preheating section. It can be seen that the high-temperature flue gas in the second preheating section is led out to the outside of the chain grate, and the denitration reactor is additionally used for denitration treatment. Denitration is not directly performed in the high-temperature preheating section of the chain grate, which increases the energy consumption and cost of flue gas denitration.

[0005] CN206168206U discloses a chain grate-rotary kiln denitrification system, which includes a first preheating section and a second preheating section for heating pellets, and also includes a denitrification device for removing nitrogen oxides in flue gas. The denitrification device is arranged in the inner cavity of the second preheating section, but the denitrification device is parallel to the ground, and the denitrification agent is sprayed in a horizontal path. The flue gas in the chain grate smoke hood area cannot contact the denitrification agent and denitrification cannot be achieved. That is, it has the disadvantages of uneven mixing of the sprayed denitrification agent and the flue gas and a short reaction residence time, resulting in low denitrification efficiency and a large subsequent flue gas treatment load.

[0006] Therefore, it is urgent to develop a denitrification system and denitrification method for roasting flue gas in a chain grate-rotary kiln to improve the denitrification efficiency of the SNCR reaction section and reduce the subsequent processing load. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the object of the present invention is to provide a denitrification device system for roasting flue gas in a chain grate-rotary kiln and a denitrification method thereof, wherein the second preheating section of the chain grate in the denitrification device system includes at least N denitrification sections, and a plurality of denitrification agent injection devices inclined upward along the flue gas conveying direction are provided in the N denitrification sections; by regulating the distribution layout of the denitrification agent injection devices in the N denitrification sections and the direction of their nozzles, the denitrification agent is fully and evenly mixed with the roasting flue gas entering the chain grate, thereby extending the residence time of the denitrification agent in the flue gas, thereby improving the denitrification efficiency, reducing the denitrification energy consumption, and alleviating the subsequent processing load.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln, wherein the denitrification device system includes a rotary kiln and a chain grate with a built-in denitrification agent injection device connected in sequence; the chain grate includes a second preheating section and a first preheating section in sequence at one end close to the rotary kiln; the denitrification agent injection device is arranged in the second preheating section of the chain grate; with the ground as the horizontal plane, the denitrification agent injection device is arranged upwardly inclined; the second preheating section includes a smoke hood area, a reaction area and a material area from top to bottom; from the second preheating section to the first preheating section, the second preheating section includes at least N denitrification sections, where N ≥ 3 (for example, it can be 3, 4, 5, 6, 7 or 8, etc.); on both sides of the first denitrification section close to the rotary kiln, the smoke hood area The position of the lower contact reaction zone is respectively provided with at least one (for example, 1, 2, 3, 4 or 5, etc.) denitrification agent injection device; on both sides of the second denitrification section close to the rotary kiln, the position of the lower contact reaction zone of the smoke hood area is respectively provided with at least one (for example, 1, 2, 3, 4 or 5, etc.) denitrification agent injection device; the position of the lower part of the reaction zone close to the material zone is respectively provided with at least one (for example, 1, 2, 3, 4 or 5, etc.) denitrification agent injection device; on both sides of the Nth denitrification section away from the rotary kiln, the position of the lower contact reaction zone of the smoke hood area is respectively provided with at least two (for example, 2, 3, 4, 5 or 6, etc.) denitrification agent injection devices distributed equidistantly.

[0010] In the present invention, the denitrification device system arranges the denitrification agent injection device in the second preheating section of the chain grate. Since the temperature range of the second preheating section of the chain grate is close to the temperature range of the SNCR denitrification treatment, there is no need to add an additional flue gas heating device, and denitrification is directly carried out in the second preheating section of the chain grate, which greatly reduces the energy consumption of denitrification. In addition, the denitrification device system is designed to be arranged from the second preheating section to the first preheating section. The second preheating section includes N denitrification sections (N≥3), and the second preheating section includes a smoke hood area, a reaction area and a material area from top to bottom. By regulating the denitrification agent injection device in each denitrification section, the denitrification agent injection device is arranged in the second preheating section. The position layout of the smoke hood area and the reaction zone allows the denitrifier to be evenly mixed with the flue gas, thereby improving the denitrification efficiency and reducing the amount of denitrifier used. At least one denitrifier injection device is provided on both sides of the second denitrification section close to the rotary kiln and at the lower part of the reaction zone close to the material area. The flue gas in the smoke hood area can also contact and react with the denitrifier to achieve denitrification. The direction of the denitrifier injection device is designed to change the injection path of the denitrifier from horizontal throwing to oblique throwing, thereby extending the residence time of the denitrifier in the flue gas, making the SNCR reaction more complete, improving the denitrification efficiency, and reducing the denitrification cost.

[0011] Preferably, at least two (for example, 2, 3, 4, 5 or 6, etc.) denitrification agent injection devices are equidistantly provided at the positions of the lower contact reaction zones of the smoke hood area on both sides of the first denitrification section.

[0012] It is worth noting that "equidistant distribution" means that the position of the denitrification agent injection device divides the first denitrification section into equidistant and uniform sections; in actual application, the more denitrification agent injection devices are set, the higher the denitrification efficiency is, but at the same time, the denitrification agent cannot be fully utilized and is wasted. Therefore, it is preferred to set 4 to 6 denitrification agent injection devices.

[0013] Preferably, in the first denitrification section, at least one (for example, one, two, three or four) denitrification agent injection device is arranged at the flue gas inlet of the chain grate.

[0014] The present invention further preferably has at least one denitrification agent injection device disposed at the flue gas inlet of the chain grate in the first denitrification section, so that a portion of the flue gas reacts with the denitrification agent at the flue gas inlet for denitrification, thereby reducing the NO in the flue gas when it enters the subsequent denitrification section. x concentration, further improving the flue gas treatment efficiency.

[0015] Preferably, the length of the first denitrification section accounts for 5% to 15% of the length of the second preheating section, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.

[0016] Preferably, along the flue gas conveying direction, the denitrification agent injection device in the second denitrification section divides the second denitrification section into equal intervals.

[0017] Preferably, on both sides of the second denitrification section, at least two (for example, 2, 3, 4, 5 or 6, etc.) equally spaced denitrification agent injection devices are respectively provided at the position of the lower contact reaction zone of the fume hood area; at least two (for example, 2, 3, 4, 5 or 6, etc.) equally spaced denitrification agent injection devices are respectively provided at the position of the lower part of the reaction zone close to the material zone; and in the second denitrification section, the denitrification agent injection device of the lower contact reaction zone of the fume hood area and the denitrification agent injection device of the lower part of the reaction zone close to the reaction zone are located on the same longitudinal section of the chain grate.

[0018] It is worth noting that the "equidistant division" and "equidistant distribution" in the present invention both refer to the uniform distribution of the denitrification agent injection device in the denitrification section in which it is located. When there is only one denitrification agent injection device, it is located in the middle of the denitrification section. This design allows the denitrification agent sprayed by the denitrification agent injection device to be evenly distributed, avoiding the problem of too much or too little denitrification agent in a certain area, resulting in the inefficient denitrification of the roasting flue gas.

[0019] Preferably, the length of the second denitrification section accounts for 5% to 15% of the length of the second preheating section, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.

[0020] Preferably, when N≥4, no denitrification agent injection device is provided in the third denitrification section close to the rotary kiln; and the distance reached by the denitrification agent sprayed by the denitrification agent injection device in the second denitrification section toward the third denitrification section is counted as L1, and the ratio of the length L2 of the third denitrification section to L1 is (0.7-0.9):1, for example, it can be 0.7:1, 0.8:1 or 0.9:1, etc.

[0021] The denitrification device system of the present invention arranges the position of the denitrification agent injection device in the second denitrification section, and at least one denitrification agent injection device is respectively provided at the position of the lower contact reaction zone of the smoke hood area in the second denitrification section, combined with its upward inclined setting; the denitrification agent injection path is changed from horizontal throwing to oblique throwing, and by adjusting the position and inclination angle of the denitrification agent injection device, and controlling the length of the third denitrification section (the ratio of L2 to L1 is (0.7~0.9):1), the denitrification agent sprayed from the second denitrification section can enter the third denitrification section and react with the flue gas entering the third denitrification section; then, there is no need to set a denitrification agent injection device in the third denitrification section, and denitrification treatment of part of the flue gas entering the third denitrification section can be achieved.

[0022] Preferably, when N≥4, the length of the third denitration section accounts for 15% to 25% of the length of the second preheating section, for example, it can be 15%, 17%, 20%, 23% or 25%.

[0023] Preferably, the Nth denitrification section occupies 20% to 90% of the length of the second preheating section, for example, it can be 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90%, etc. Preferably, when N is 4, the Nth denitrification section occupies 45% to 75% of the length of the second preheating section, for example, it can be 45%, 50%, 55%, 60%, 65%, 70% or 75%, etc.

[0024] The present invention further prefers that the length of the first denitrification section, the length of the second denitrification section and the length of the Nth denitrification section account for 5% to 15%, 5% to 15% and 20% to 90% of the length of the second preheating section respectively; combined with the position layout and tilt angle adjustment of the denitrification agent injection device, the denitrification agent is evenly distributed in the flue gas in the smoke hood, and the residence time of the denitrification agent in the flue gas is extended, thereby improving the denitrification efficiency.

[0025] Preferably, the distance between the lower part of the reaction zone near the material zone and the material zone is recorded as h, the overall height of the reaction zone is recorded as H, and the ratio of h / H is in the range of 0.3 to 0.4, for example, it can be 0.3, 0.32, 0.34, 0.36, 0.38 or 0.4, etc.

[0026] The present invention further controls the ratio of the distance between the lower part of the reaction zone near the material zone and the material zone to the overall height of the reaction zone to be in the range of 0.3 to 0.4, and arranges the denitrification agent injection device within a specific height range of the reaction zone, and cooperates with the denitrification agent injection device arranged at the lower part of the fume hood area near the reaction zone to ensure the uniform distribution and average residence time of the denitrification agent in the second preheating section of the chain grate, thereby further improving the denitrification efficiency; if the distance between the lower part of the reaction zone near the material zone and the material zone is too low, most of the denitrification agent is counted into the material zone, and almost no denitrification agent is distributed in the middle and upper parts of the reaction zone, resulting in a decrease in the denitrification efficiency; if the distance between the lower part of the reaction zone near the material zone and the material zone is too low, the denitrification agent is concentrated in the fume hood area of the chain grate and the upper part of the reaction zone near the fume hood area, and the flue gas in the middle and lower parts of the reaction zone near the material area cannot contact the denitrification agent, resulting in a significant decrease in the denitrification efficiency.

[0027] Preferably, with the ground as the horizontal plane, the nozzle of the denitrification agent injection device is oriented toward the flue gas conveying direction and is inclined upward by 15° to 60°, for example, 15°, 30°, 45° or 60°.

[0028] Preferably, the nozzle of the denitrification agent injection device at the lower part of the reaction zone near the material zone is inclined upward by 30° to 60° toward the flue gas conveying direction, for example, it can be 30°, 35°, 40°, 45°, 50°, 55° or 60°, preferably 40° to 50°.

[0029] Preferably, the nozzle of the denitrification agent injection device in the lower contact reaction zone of the fume hood area is inclined upward by 15° to 40° toward the flue gas conveying direction, for example, it can be 15°, 20°, 25°, 30°, 35° or 40°.

[0030] The present invention further adjusts the upward inclination angle of the denitrification agent injection device to 15 to 60 degrees, so that the injection path of the denitrification agent is changed from horizontal throwing to oblique throwing, so that the denitrification agent is evenly distributed in the entire second preheating section, and the flue gas in the smoke hood area can also come into contact with the denitrification agent; and the change from horizontal throwing to oblique throwing path prolongs the residence time of the denitrification agent in the flue gas, thereby also being able to improve the denitrification efficiency.

[0031] It is worth noting that, the present invention further prefers that the nozzle of the denitrification agent injection device in the lower part of the reaction zone near the material zone is inclined upward by 40° to 50° toward the flue gas conveying direction, and further prefers that the nozzle of the denitrification agent injection device in the lower contact reaction zone of the smoke hood area is inclined upward by 15° to 40° toward the flue gas conveying direction; the two cooperate with each other to make the denitrification agent evenly distributed in the second preheating section (i.e., the denitrification section), thereby maximizing the contact area between the denitrification agent and the flue gas, and the two fully react to improve the denitrification efficiency of the flue gas.

[0032] Among them, it is further preferred that the nozzle of the denitrification agent injection device in the lower part of the reaction zone near the material area is inclined upward by 40° to 50° toward the flue gas conveying direction, and the inclination angle is relatively large, so that the denitrification agent can cover the reaction zone. If the angle is too small, the denitrification agent cannot enter the upper part of the reaction zone near the fume hood area; if the angle is too large, the denitrification agent cannot reach the lower part of the reaction zone near the material area; at the same time, it is further preferred that the nozzle of the denitrification agent injection device in the lower part of the fume hood area contacting the reaction zone is inclined upward by 15° to 40° toward the flue gas conveying direction, and the inclination angle is relatively small, so that the denitrification agent is evenly distributed in the fume hood area; if the angle is too small, the flue gas in the upper part of the fume hood area cannot contact the denitrification agent; if the angle is too large, most of the denitrification agent is sprayed on the inner wall of the fume hood area; as a result, most of the flue gas in the fume hood area cannot contact the denitrification agent, and the denitrification agent is wasted.

[0033] It is worth noting that the denitrification device system of the present invention does not impose any restrictions on the denitrification agent injection device. For example, it can be a spray gun that can realize the injection of the denitrification agent.

[0034] Preferably, the jet angle of the denitrification agent injection device is 55° to 65°, for example, it can be 55°, 60° or 65°.

[0035] Preferably, the chain grate further includes an exhaust drying section and a blast drying section in sequence at the end of the first preheating section away from the second preheating section.

[0036] Preferably, a bellows is provided at the bottom of the chain grate.

[0037] The denitrification device system of the present invention further includes an exhaust drying section, a blast drying section and a bellows, which can be used for further treatment of the subsequent flue gas.

[0038] In a second aspect, the present invention provides a method for denitrifying flue gas from roasting in a chain grate-rotary kiln, wherein the denitrification method is performed using the denitrification device system described in the first aspect.

[0039] The denitrification method of the present invention adopts the denitrification device system described in the first aspect, so that the denitrification agent is evenly distributed in the second preheating section of the chain grate, fully contacts and reacts with the flue gas, and achieves the effect of using a smaller amount of denitrification agent to achieve higher denitrification efficiency.

[0040] Preferably, the denitration method comprises: reacting the roasting flue gas in the rotary kiln with a denitration agent injected in an oblique path to perform denitration treatment.

[0041] It is worth mentioning that the “oblique projection path” means that the denitrification agent sprayed out by the denitrification agent injection device is sprayed in an oblique projection motion; that is, its path is first obliquely upward and then obliquely downward.

[0042] Preferably, the denitrification agent includes ammonia, which can be selected from any one or a combination of at least two of aqueous ammonia, urea or liquid ammonia, wherein typical but non-limiting combinations include aqueous ammonia and urea or urea and liquid ammonia.

[0043] Preferably, the roasting flue gas enters the first denitrification section, the second denitrification section and the Nth denitrification section in sequence, and reacts with the denitrification agents in the first denitrification section, the second denitrification section and the Nth denitrification section respectively to perform denitrification treatment, where N≥3 (for example, it can be 3, 4, 5, 6, 7 or 8, etc.).

[0044] Preferably, when N≥4, when the flue gas enters the third denitrification section, it reacts with the denitrification agent injected by the denitrification agent injection device in the second denitrification section to perform denitrification treatment.

[0045] In the denitrification method of the present invention, it is further preferred that N≥4. Since the denitrification agent sprayed by the denitrification agent spraying device arranged in the second denitrification section of the denitrification device system can be distributed in the third denitrification section, there is no need to set up a denitrification agent spraying device in the third denitrification section. When the flue gas enters the third denitrification section, it can react with the denitrification agent sprayed by the denitrification agent spraying device in the second denitrification section.

[0046] Preferably, with the ground as the horizontal plane, the oblique injection angle of the denitrification agent is 15° to 60° upward along the flue gas conveying direction, for example, it can be 15°, 30°, 45° or 60°.

[0047] Preferably, the oblique injection angle of the denitrification agent in the lower part of the reaction zone near the material zone is 30° to 60° upward along the flue gas conveying direction, for example, it can be 30°, 35°, 40°, 45°, 50°, 55° or 60°, preferably 40° to 50°.

[0048] Preferably, the oblique injection angle of the denitrification agent in the lower contact reaction zone of the fume hood area is 15° to 40° upward along the flue gas conveying direction, for example, it can be 15°, 20°, 25°, 30°, 35° or 40°.

[0049] Preferably, the average residence time of the denitrification agent in the flue gas is 0.8 to 1.3 s, for example, it can be 0.8 s, 0.9 s, 1.0 s, 1.1 s, 1.2 s or 1.3 s.

[0050] Preferably, the flow rate of the flue gas is 500000m 3 / h~1000000m 3 / h, for example, it can be 500000m 3 / h、600000m 3 / h、700000m 3 / h、800000m 3 / h、900000m 3 / h or 1000000m 3 / h, etc.

[0051] Preferably, the NO in the flue gas x The concentration is 900~1100mg / Nm 3 , for example, it can be 900mg / Nm 3 、1000mg / Nm 3 or 1100mg / Nm 3 wait.

[0052] Preferably, the total amount of the denitrification agent is equal to the amount of NO in the flue gas. x The molar ratio of the total amount is (0.8-1.2):1, for example, it can be 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1.

[0053] The denitrification method of the present invention adopts the denitrification device system described in the first aspect to denitrify the roasting flue gas. By designing the position distribution and the upward inclination angle of the denitrification agent injection device, the denitrification agent can be evenly distributed in the second preheating section during the denitrification treatment process, and the flue gas fully reacts with the denitrification agent, thereby improving the denitrification efficiency; and by controlling the mass ratio of the denitrification agent sprayed from the denitrification agent injection device in each denitrification section, the utilization of the denitrification agent is maximized, the amount of denitrification agent required for denitrification is reduced, and waste is avoided.

[0054] As a further preferred technical solution of the present invention, the denitration method comprises:

[0055] The flow rate in the rotary kiln is 500,000 to 1,000,000 m 3 / h、NO x Concentration is 900~1100mg / Nm 3 The roasting flue gas reacts with the denitrification agent injected in an oblique throwing path to perform denitrification treatment;

[0056] Wherein, with the ground as the horizontal plane, the oblique injection path of the denitrification agent is inclined upward by 15° to 60° along the flue gas conveying direction; the average residence time of the denitrification agent in the flue gas is 0.8 to 1.3 seconds;

[0057] The total amount of the denitrification agent is proportional to the NO in the flue gas x The molar ratio of the total amount is (0.8-1.2):1.

[0058] The numerical range described in the present invention includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The present invention provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln. The denitrification device system optimizes the distribution layout and angle of the denitrification agent injection device in the second preheating section of the chain grate; the second preheating section is divided into at least N denitrification sections (N≥3), and the position distribution of the denitrification agent injection device in each denitrification section is controlled, and the length of each denitrification section and the height range of the denitrification agent injection device arranged in the reaction zone near the material zone are further controlled, so that the denitrification agent sprayed is evenly distributed in the second preheating section, the injection path of the denitrification agent is changed from horizontal throwing to oblique throwing, and the residence time of the denitrification agent is extended to more than 0.8s; the flue gas entering the chain grate can fully contact with the denitrification agent, and the denitrification efficiency in the chain grate equipment is improved to more than 45%.

[0061] (2) The present invention provides a method for denitrifying flue gas from roasting in a chain grate-rotary kiln. The denitrification method is carried out using the denitrification device system of the present invention. By designing the position layout of the denitrification agent injection device and the upward inclination angle, the residence time of the denitrification agent is further extended to more than 1.2s. The denitrification efficiency in the chain grate equipment is increased to more than 50%, reducing the amount of denitrification agent used. Compared with other traditional denitrification devices with a denitrification efficiency of only about 20 to 30% in the chain grate equipment, the denitrification efficiency is greatly improved, which greatly reduces the pressure and cost of subsequent denitrification equipment and reduces the energy consumption of subsequent treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 1 is a schematic structural diagram of a denitration device system for roasting flue gas in a grate-rotary kiln provided in Example 1 of the present invention;

[0063] Figure 2 This is a single-side position distribution diagram of a denitrification agent injection device in a denitrification device system provided in Example 1 of the present invention;

[0064] Figure 3 1 is a longitudinal cross-sectional view of the second denitration section in the second preheating section of the grate in the denitration device system provided in Example 1 of the present invention;

[0065] Figure 4 This is a single-side position distribution diagram of a denitrification agent injection device in a denitrification device system provided in Example 2 of the present invention;

[0066] Figure 5 This is a single-side position distribution diagram of a denitrification agent injection device in a denitrification device system provided in Example 3 of the present invention;

[0067] Figure 6 This is a single-side position distribution diagram of a denitrification agent injection device in a denitrification device system provided in Example 7 of the present invention;

[0068] Figure 7 This is a single-side position distribution diagram of the denitrification agent injection device in the denitrification device system provided in Comparative Example 1 of the present invention;

[0069] Figure 8 This is a single-side position distribution diagram of the denitrification agent injection device in the denitrification device system provided in Comparative Example 2 of the present invention;

[0070] In the figure: 1 to 18, bellows; 19, rotary kiln; 20, chain grate; 21, second preheating section; 22, first preheating section; 23, exhaust drying section; 24, blast drying section. DETAILED DESCRIPTION

[0071] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0072] It should be understood that, in the description of the present invention, the terms "inside", "one end", "close to", "far away from", "up", "down", "both sides", "equidistant", "longitudinal", "towards", "middle position", "lower", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. The terms "first", "second", etc. do not indicate the importance of the section, and therefore cannot be understood as a limitation on the present invention.

[0073] 1. Implementation

[0074] Example 1

[0075] This embodiment provides a chain grate-rotary kiln flue gas denitrification device system, such as Figure 1 As shown, the denitrification device system includes a rotary kiln and a chain grate with a built-in denitrification agent injection device connected in sequence; wherein, the denitrification agent injection device adopts a spray gun; the chain grate 20 includes a second preheating section 21 and a first preheating section 22 in sequence at one end close to the rotary kiln 19; the denitrification agent injection device is arranged in the second preheating section 21 of the chain grate 20; the second preheating section 21 includes a smoke hood area, a reaction area and a material area from top to bottom; the chain grate 20 also includes an exhaust drying section 23 and a blast drying section 24 in sequence at one end of the first preheating section 22 away from the second preheating section 21; 18 bellows (1 to 18) are provided at the bottom of the chain grate 20.

[0076] like Figure 2 As shown, it is only a single-side position distribution diagram of the denitrification agent injection device in the denitrification device system provided in this embodiment, and the other side is symmetrically arranged with it; from the second preheating section 21 to the first preheating section 22, the second preheating section 21 includes 4 denitrification sections; the length of the first denitrification section accounts for 10% of the length of the second preheating section 21; the length of the second denitrification section accounts for 10% of the length of the second preheating section 21; the length of the third denitrification section accounts for 20% of the length of the second preheating section 21; the length of the fourth denitrification section accounts for 60% of the length of the second preheating section 21; the ratio of the distance between the position of the lower part of the reaction zone close to the material zone and the material zone to the overall height of the reaction zone is 0.33.

[0077] On both sides of the first denitrification section near the rotary kiln 19, two denitrification agent injection devices are respectively provided at the position of the lower contact reaction zone of the smoke hood area; one of the denitrification agent injection devices is provided at the flue gas inlet of the chain grate 20; and the other denitrification agent injection device divides the first denitrification section into equal parts (i.e., it is provided in the middle position of the first denitrification section).

[0078] On both sides of the second denitrification section near the rotary kiln 19, a denitrification agent injection device is respectively provided at the position of the lower contact reaction zone of the smoke hood area; a denitrification agent injection device is respectively provided at the position near the material area below the reaction zone; and the four denitrification agent injection devices in the second denitrification section divide the second denitrification section into equal parts (i.e., in the middle position) along the flue gas conveying direction, and are located on the same longitudinal cross-section of the chain grate 20;

[0079] No denitrification agent injection device is provided in the third denitrification section near the rotary kiln 19; and the ratio of the length of the third denitrification section to the distance reached by the denitrification agent injection device in the second denitrification section toward the third denitrification section is 0.8:1;

[0080] On both sides of the fourth denitration section away from the rotary kiln 19, six denitration agent injection devices are equidistantly arranged at the position of the lower contact reaction zone of the smoke hood area.

[0081] like Figure 3 As shown, with the ground as the horizontal plane, the nozzle of the denitrification agent injection device is facing the flue gas conveying direction, and the nozzle of the denitrification agent flue gas injection device in the lower contact reaction zone of the fume hood area is inclined upward by 30° along the flue gas conveying direction; the nozzle of the denitrification agent flue gas injection device in the lower part of the reaction zone close to the material area is inclined upward by 45° along the flue gas conveying direction; the jet angle of the denitrification agent injection device is 60°.

[0082] This embodiment also provides a denitration method for flue gas from a grate-rotary kiln using the above-mentioned denitration device system. The denitration method comprises:

[0083] The flow rate in the rotary kiln is 600000m 3 / h、NO x Concentration is 1000mg / Nm 3 The roasting flue gas reacts with the ammonia injected in an oblique path to perform denitrification treatment;

[0084] With the ground as the horizontal plane, the oblique injection angle of the ammonia gas in the lower part of the reaction zone near the material area is 45 degrees upward along the flue gas conveying direction, and the oblique injection angle of the ammonia gas in the lower part of the fume hood area contacting the reaction zone is 30 degrees upward along the flue gas conveying direction; the average residence time of the ammonia gas in the flue gas is 1.3 seconds;

[0085] The total amount of ammonia used is related to the NO in the flue gas x The molar ratio of the total amount is 1:1.

[0086] Example 2

[0087] The present embodiment provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln, wherein the denitrification device system includes a rotary kiln and a chain grate with a built-in denitrification agent injection device connected in sequence; wherein the denitrification agent injection device adopts a spray gun; the chain grate includes a second preheating section and a first preheating section in sequence at one end close to the rotary kiln; the denitrification agent injection device is arranged in the second preheating section of the chain grate; the second preheating section includes a smoke hood area, a reaction area and a material area from top to bottom; the chain grate also includes an exhaust drying section and a blast drying section in sequence at one end of the first preheating section away from the second preheating section; and 18 bellows are provided at the bottom of the chain grate.

[0088] like Figure 4As shown, it is only a single-side position distribution diagram of the denitrification agent injection device in the denitrification device system provided in this embodiment, and the other side is symmetrically arranged with it; from the second preheating section to the first preheating section, the second preheating section includes 4 denitrification sections; the length of the first denitrification section accounts for 5% of the length of the second preheating section; the length of the second denitrification section accounts for 15% of the length of the second preheating section; the length of the third denitrification section accounts for 25% of the length of the second preheating section; the length of the fourth denitrification section accounts for 55% of the length of the second preheating section; the ratio of the distance between the position of the lower part of the reaction zone close to the material zone and the material zone to the overall height of the reaction zone is 0.4.

[0089] On both sides of the first denitrification section close to the rotary kiln, a denitrification agent injection device is respectively provided at the position of the lower contact reaction zone of the smoke hood area; the denitrification agent injection device is provided at the flue gas inlet of the chain grate.

[0090] On both sides of the second denitrification section near the rotary kiln, two equally spaced denitrification agent injection devices are respectively provided at the position of the lower contact reaction zone of the smoke hood area; two equally spaced denitrification agent injection devices are respectively provided at the position of the lower part of the reaction zone near the material area;

[0091] No denitrification agent injection device is provided in the third denitrification section near the rotary kiln; and the ratio of the length of the third denitrification section to the distance reached by the denitrification agent injection device in the second denitrification section toward the third denitrification section is 0.7:1;

[0092] On both sides of the fourth denitrification section away from the rotary kiln, four denitrification agent injection devices are respectively provided at the position of the lower contact reaction zone of the smoke hood area with equal distances.

[0093] With the ground as the horizontal plane, the nozzle of the denitrification agent injection device is facing the direction of flue gas transportation. The nozzle of the denitrification agent flue gas injection device in the lower contact reaction zone of the fume hood area is inclined upward by 15° along the direction of flue gas transportation; the nozzle of the denitrification agent flue gas injection device in the lower part of the reaction zone close to the material area is inclined upward by 50° along the direction of flue gas transportation; the jet angle of the denitrification agent injection device is 60°.

[0094] This embodiment also provides a denitration method for flue gas from a grate-rotary kiln using the above-mentioned denitration device system. The denitration method comprises:

[0095] The flow rate in the rotary kiln is 600000m 3 / h、NO x Concentration is 1000mg / Nm 3 The roasting flue gas reacts with the ammonia injected in an oblique path to perform denitrification treatment;

[0096] With the ground as the horizontal plane, the oblique injection angle of the ammonia gas in the lower part of the reaction zone near the material area is 50 degrees upward along the flue gas conveying direction, and the oblique injection angle of the ammonia gas in the lower part of the fume hood area contacting the reaction zone is 15 degrees upward along the flue gas conveying direction; the average residence time of the ammonia gas in the flue gas is 1.2 seconds;

[0097] The total amount of ammonia used is related to the NO in the flue gas x The molar ratio of the total amount is 1:1.

[0098] Example 3

[0099] The present embodiment provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln, wherein the denitrification device system includes a rotary kiln and a chain grate with a built-in denitrification agent injection device connected in sequence; wherein the denitrification agent injection device adopts a spray gun; the chain grate includes a second preheating section and a first preheating section in sequence at one end close to the rotary kiln; the denitrification agent injection device is arranged in the second preheating section of the chain grate; the second preheating section includes a smoke hood area, a reaction area and a material area from top to bottom; the chain grate also includes an exhaust drying section and a blast drying section in sequence at one end of the first preheating section away from the second preheating section; and 18 bellows are provided at the bottom of the chain grate.

[0100] like Figure 5 As shown, it is only a single-side position distribution diagram of the denitrification agent injection device in the denitrification device system provided in this embodiment, and the other side is symmetrically arranged with it; from the second preheating section to the first preheating section, the second preheating section includes 4 denitrification sections; the length of the first denitrification section accounts for 15% of the length of the second preheating section; the length of the second denitrification section accounts for 5% of the length of the second preheating section; the length of the third denitrification section accounts for 15% of the length of the second preheating section; the length of the fourth denitrification section accounts for 65% of the length of the second preheating section; the ratio of the distance between the position of the lower part of the reaction zone close to the material zone and the material zone to the overall height of the reaction zone is 0.3.

[0101] On both sides of the first denitrification section close to the rotary kiln, three equally spaced denitrification agent injection devices are respectively provided at the position of the lower contact reaction zone of the smoke hood area; one of the denitrification agent injection devices is provided at the flue gas inlet of the chain grate.

[0102] On both sides of the second denitration section near the rotary kiln, a denitration agent injection device is respectively provided at the position of the lower contact reaction zone of the smoke hood area; and a denitration agent injection device is respectively provided at the position of the lower part of the reaction zone near the material area;

[0103] No denitrification agent injection device is provided in the third denitrification section near the rotary kiln; and the ratio of the length of the third denitrification section to the distance reached by the denitrification agent injection device in the second denitrification section toward the third denitrification section is 0.9:1;

[0104] On both sides of the fourth denitration section away from the rotary kiln, six denitration agent injection devices are equidistantly arranged at the position of the lower contact reaction zone of the smoke hood area.

[0105] With the ground as the horizontal plane, the nozzle of the denitrification agent injection device is facing the direction of flue gas transportation. The nozzle of the denitrification agent flue gas injection device in the lower contact reaction zone of the fume hood area is inclined upward by 40° along the flue gas transportation direction; the nozzle of the denitrification agent flue gas injection device in the lower part of the reaction zone close to the material area is inclined upward by 42° along the flue gas transportation direction; the jet angle of the denitrification agent injection device is 60°.

[0106] This embodiment also provides a denitration method for flue gas from a grate-rotary kiln using the above-mentioned denitration device system. The denitration method comprises:

[0107] The flow rate in the rotary kiln is 600000m 3 / h、NO x Concentration is 1000mg / Nm 3 The roasting flue gas reacts with the ammonia injected in an oblique path to perform denitrification treatment;

[0108] Wherein, with the ground as the horizontal plane, the oblique injection angle of the ammonia gas in the lower part of the reaction zone near the material zone is 42 degrees upward along the flue gas conveying direction, and the oblique injection angle of the ammonia gas in the lower part of the fume hood zone contacting the reaction zone is 40 degrees upward along the flue gas conveying direction; the average residence time of the ammonia gas in the flue gas is 1.3 seconds;

[0109] The total amount of ammonia used is related to the NO in the flue gas x The molar ratio of the total amount is 1:1.

[0110] Example 4

[0111] This embodiment provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln. Except that the nozzle of the denitrification agent flue gas injection device in the lower contact reaction zone of the smoke hood area of the denitrification device system is tilted upward by 45 degrees along the flue gas conveying direction, the rest is the same as Example 1.

[0112] This embodiment also provides a denitrification method for roasting flue gas in a chain grate-rotary kiln using the above-mentioned denitrification device system. Except that the oblique injection angle of ammonia gas changes accordingly with the change of the denitrification device system, the rest of the denitrification method is the same as Example 1.

[0113] Example 5

[0114] This embodiment provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln. Except that the nozzle of the denitrification agent flue gas injection device at the lower part of the reaction zone near the material area in the denitrification device system is tilted upward by 35 degrees along the flue gas conveying direction, the rest is the same as Example 1.

[0115] This embodiment also provides a denitrification method for roasting flue gas in a chain grate-rotary kiln using the above-mentioned denitrification device system. Except that the oblique injection angle of ammonia gas changes accordingly with the change of the denitrification device system, the rest of the denitrification method is the same as Example 1.

[0116] Example 6

[0117] This embodiment provides a denitrification device system for roasting flue gas in a chain grate-rotary kiln. Except that the nozzle of the denitrification agent flue gas injection device at the lower part of the reaction zone near the material area is inclined upward by 60° along the flue gas conveying direction, the rest is the same as Example 1.

[0118] This embodiment also provides a denitrification method for roasting flue gas in a chain grate-rotary kiln using the above-mentioned denitrification device system. Except that the oblique injection angle of ammonia gas changes accordingly with the change of the denitrification device system, the rest of the denitrification method is the same as Example 1.

[0119] Example 7

[0120] This embodiment provides a chain grate-rotary kiln flue gas denitrification device system, such as Figure 6 As shown, the denitrification device system includes only three denitrification sections except that the second preheating section only includes three denitrification sections. The length of the third denitrification section accounts for 80% of the length of the second preheating section. On both sides of the third denitrification section, seven denitrification agent injection devices are equidistantly arranged at the positions of the lower contact reaction zone of the smoke hood area. The rest are the same as those in Example 1.

[0121] This embodiment also provides a denitrification method for roasting flue gas in a chain grate-rotary kiln. The denitrification method is the same as that of Example 1 except that the denitrification device system described in this embodiment is used.

[0122] 2. Comparative Example

[0123] Comparative Example 1

[0124] This comparative example provides a chain grate-rotary kiln flue gas denitrification device system, such as Figure 7As shown, the denitrification device system is the same as Example 1 except that no denitrification agent injection device is provided at the position of the lower part of the reaction zone near the material zone on both sides of the second denitrification section near the rotary kiln, and a denitrification agent injection device is provided at the position of the lower part of the smoke hood zone contacting the reaction zone on both sides of the third denitrification section near the rotary kiln.

[0125] This comparative example also provides a denitration method for roasting flue gas in a chain grate-rotary kiln. The denitration method is the same as Example 1 except that the denitration device system provided in this comparative example is used.

[0126] Comparative Example 2

[0127] This comparative example provides a chain grate-rotary kiln flue gas denitrification device system, such as Figure 8 As shown, the denitrification device system is the same as Example 1 except that no denitrification agent injection device is provided in the fourth denitrification section, and one denitrification agent injection device is added at the lower part of the reaction zone near the material zone on both sides of the first denitrification section and the third denitrification section, and one denitrification agent injection device is added at the position where the smoke hood zone contacts the reaction zone in the third denitrification section.

[0128] This comparative example also provides a denitration method for roasting flue gas in a chain grate-rotary kiln. The denitration method is the same as Example 1 except that the denitration device system provided in this comparative example is used.

[0129] Comparative Example 3

[0130] This comparative example provides a denitration device system for roasting flue gas in a chain grate-rotary kiln. The denitration device system is the same as Example 1 except that the denitration agent injection device is horizontally arranged (with the ground as the horizontal plane).

[0131] This comparative example also provides a denitrification method for roasting flue gas in a chain grate-rotary kiln. The denitrification method is the same as Example 1 except that the denitrification device system provided in this comparative example is used, that is, the denitrification agent is sprayed horizontally.

[0132] 3. Test Results

[0133] The average residence time of ammonia in flue gas and the denitration rate of flue gas in the denitration methods provided in the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0134] Table 1

[0135]

[0136] From Table 1 we can see the following points:

[0137] (1) Based on Examples 1 to 3, it can be seen that the denitrification device system and denitrification method provided by the present invention can extend the average residence time of the denitrification agent in the flue gas to more than 1.2s by adjusting the position layout of the denitrification agent injection device in N denitrification sections and the upward inclination angle of the denitrification agent injection device along the flue gas entry direction, thereby increasing the denitrification rate of the roasting flue gas to more than 50%.

[0138] (2) Combining Example 1 with Examples 4 to 6, it can be seen that since the denitrification agent injection device in Example 4 is tilted upward at an angle that is too large along the flue gas conveying direction, most of the denitrification agent is sprayed on the inner wall of the smoke hood, and the smoke in the smoke hood cannot contact the denitrification agent, and the two cannot fully react, and the denitrification rate drops to 46%; while the denitrification agent injection device in Examples 5 and 6 is tilted upward at an angle that is too large or too small along the flue gas conveying direction, resulting in uneven distribution of the denitrification agent in the reaction zone, resulting in an average residence time of the denitrification agent in the flue gas being as short as less than 1.0s, and the denitrification rate dropping to less than 47%; It can be seen from this that the present invention further prefers that the nozzle of the denitrification agent flue gas injection device in the lower part of the fume hood area contacting the reaction zone is tilted upward at 15° to 40° along the flue gas conveying direction, and the oblique injection angle of the denitrification agent in the lower part of the reaction zone near the material area is tilted upward at 40° to 50° along the flue gas conveying direction. The two work synergistically to extend the average residence time of the denitrification agent in the flue gas and improve the denitrification efficiency.

[0139] (3) Combining Example 1 and Example 7, it can be seen that since the denitrification system described in Example 7 only includes 3 denitrification sections, the required amount of denitrification agent is large, and more denitrification agent injection devices need to be set up, while the denitrification rate is not significantly improved. Therefore, it can be seen that the present invention further preferably sets N denitrification sections (N≥4), and at the same denitrification rate, the denitrification agent consumed is less.

[0140] (4) Combining Example 1 and Comparative Examples 1 to 3, since the denitrification device system used in Comparative Example 1 does not have a denitrification agent injection device installed at the lower part of the reaction zone in the second denitrification section near the material zone, the average residence time of the denitrification agent in the flue gas is as short as 0.6s, and the denitrification rate drops to 32%; while the denitrification agent injection devices in Comparative Example 2 are concentratedly installed in the 1st to 3rd denitrification sections, and the denitrification rate drops to 35%; and the denitrification agent injection device in Comparative Example 3 is installed horizontally, and the denitrification agent sprayed therefrom is a horizontal throwing path, the residence time of the denitrification agent in the flue gas becomes shorter, only 0.5s, and the denitrification rate drops to 30%.

[0141] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A denitrification device system for roasting flue gas in a chain grate-rotary kiln, characterized in that: The denitrification device system includes a rotary kiln and a chain grate with a built-in denitrification agent injection device connected in sequence; The chain grate comprises a second preheating section and a first preheating section in sequence at one end thereof close to the rotary kiln; the denitrification agent injection device is arranged in the second preheating section of the chain grate; the denitrification agent injection device is arranged to be inclined upward with the ground as the horizontal plane; The second preheating section includes a fume hood area, a reaction area and a material area from top to bottom; in the direction from the second preheating section to the first preheating section, the second preheating section includes at least N denitration sections, where N is greater than or equal to 4; At least one denitrification agent injection device is respectively provided at the position of the lower contact reaction zone of the smoke hood area on both sides of the first denitrification section close to the rotary kiln; At least one denitrification agent injection device is provided on both sides of the second denitrification section near the rotary kiln, at a position where the lower part of the smoke hood area contacts the reaction zone; at least one denitrification agent injection device is provided at a position near the material zone below the reaction zone; No denitrification agent injection device is provided in the third denitrification section near the rotary kiln; and the distance reached by the denitrification agent injected by the denitrification agent injection device in the second denitrification section toward the third denitrification section is defined as L1, and the ratio of the length L2 of the third denitrification section to L1 is (0.7-0.9):1; At least two denitrification agent injection devices are equidistantly provided at the positions of the lower contact reaction zone of the fume hood area on both sides of the Nth denitrification section away from the rotary kiln; The nozzle of the denitrification agent injection device at the lower part of the reaction zone close to the material area is inclined upward by 40°~50° along the flue gas conveying direction; the nozzle of the denitrification agent injection device at the lower part of the fume hood area contacting the reaction zone is inclined upward by 15°~40° along the flue gas conveying direction.

2. The denitration device system according to claim 1, characterized in that: At least two denitrification agent injection devices are equidistantly arranged at the positions of the lower contact reaction zone of the fume hood area on both sides of the first denitrification section.

3. The denitration device system according to claim 1, characterized in that: In the first denitrification section, at least one denitrification agent injection device is arranged at the flue gas inlet of the chain grate.

4. The denitration device system according to claim 1, characterized in that: The length of the first denitration section accounts for 5% to 15% of the length of the second preheating section.

5. The denitration device system according to claim 1, characterized in that: Along the flue gas conveying direction, the denitrification agent injection device in the second denitrification section divides the second denitrification section into equal parts.

6. The denitration device system according to claim 1, characterized in that: On both sides of the second denitrification section, at least two equidistantly distributed denitrification agent injection devices are respectively provided at the position of the lower contact reaction zone of the fume hood area; at least two equidistantly distributed denitrification agent injection devices are respectively provided at the lower position of the reaction zone close to the material zone; and in the second denitrification section, the denitrification agent injection device of the lower contact reaction zone of the fume hood area and the denitrification agent injection device of the lower reaction zone close to the reaction zone are located on the same longitudinal section of the chain grate.

7. The denitration device system according to claim 1, characterized in that: The length of the second denitration section accounts for 5% to 15% of the length of the second preheating section.

8. The denitration device system according to claim 1, characterized in that: The length of the third denitration section accounts for 15% to 25% of the length of the second preheating section.

9. The denitration device system according to claim 1, characterized in that: The length of the Nth denitration section accounts for 20% to 75% of the length of the second preheating section.

10. The denitration device system according to claim 1, characterized in that: When N is 4, the Nth denitration section occupies 45% to 75% of the length of the second preheating section.

11. The denitration device system according to claim 1, characterized in that: The distance between the lower portion of the reaction zone near the material zone and the material zone is recorded as h, the overall height of the reaction zone is recorded as H, and the ratio of h / H is in the range of 0.3 to 0.

4.

12. The denitration device system according to claim 1, characterized in that: The chain grate further includes an exhaust drying section and a blast drying section in sequence at one end of the first preheating section away from the second preheating section.

13. The denitration device system according to claim 1, characterized in that: A bellows is provided at the bottom of the chain grate.

14. A method for denitrification of flue gas from roasting in a chain grate-rotary kiln, characterized in that: The denitration method is carried out using the chain grate-rotary kiln flue gas denitration device system according to any one of claims 1 to 13.

15. The denitration method according to claim 14, characterized in that: The denitration method comprises: reacting the roasting flue gas in the rotary kiln with a denitrifying agent injected in an oblique throwing path to perform denitration treatment; The roasting flue gas enters the first denitration section, the second denitration section and the Nth denitration section in sequence, and reacts with the denitrification agents in the first denitration section, the second denitration section and the Nth denitration section respectively to perform denitration treatment, wherein N≥4; When the flue gas enters the third denitration section, it reacts with the denitrification agent injected by the denitrification agent injection device in the second denitration section to perform denitration treatment; The oblique injection angle of the denitrification agent in the lower part of the reaction zone near the material area is 40°~50° upward along the flue gas conveying direction; the oblique injection angle of the denitrification agent in the lower contact reaction zone of the fume hood area is 15°~40° upward along the flue gas conveying direction.

16. The denitration method according to claim 14, characterized in that: The average residence time of the denitrifier in the flue gas is 0.8-1.3 s.

17. The denitration method according to claim 14, characterized in that: The flow rate of the flue gas is 500000~1000000m 3 / h.

18. The denitration method according to claim 14, characterized in that: The NO in the flue gas x The concentration is 900~1100mg / Nm 3 .

19. The denitration method according to claim 14, characterized in that: The total amount of the denitrification agent is proportional to the NO in the flue gas x The molar ratio of the total amount is (0.8~1.2):

1.

20. The denitration method according to claim 14, characterized in that: The denitrification method includes: the flow rate in the rotary kiln is 500000~1000000m 3 / h、NO x Concentration is 900~1100mg / Nm 3 The roasting flue gas reacts with the denitrification agent injected in an oblique throwing path to perform denitrification treatment; The roasting flue gas sequentially enters the first denitration section, the second denitration section, and the Nth denitration section, and reacts with the denitrifiers in the first denitration section, the second denitration section, and the Nth denitration section, respectively, to perform denitration treatment, wherein N ≥ 4; when the flue gas enters the third denitration section, it reacts with the denitrifier injected by the denitrifier injection device in the second denitration section to perform denitration treatment; The oblique injection angle of the denitrification agent in the lower part of the reaction zone near the material area is 40° to 50° upward along the flue gas conveying direction; the oblique injection angle of the denitrification agent in the lower contact reaction zone of the fume hood area is 15° to 40° upward along the flue gas conveying direction; The average residence time of the denitrifier in the flue gas is 0.8 to 1.3 s; The total amount of the denitrification agent is proportional to the NO in the flue gas x The molar ratio of the total amount is (0.8~1.2):1.

Images