Desulfurization and denitrification integrated absorption tower and use method thereof

Abstract

The invention relates to the technical field of flue gas treatment, and discloses a desulfurization and denitrification integrated absorption tower and a using method thereof.The interior of a tower body of the absorption tower is sequentially provided with a desulfurization absorption area, a gas oxidation area and a denitrification absorption area from bottom to top, and the desulfurization absorption area is provided with a desulfurization absorption liquid pool and a desulfurization absorption liquid spraying device; the gas oxidation zone is provided with an oxidant injection grid for injecting ozone, and a plurality of nozzles with downward injection directions are uniformly arranged on the oxidant injection grid; the denitration absorption area is provided with a denitration absorption liquid pool and a denitration absorption liquid spraying device, a first demister is arranged between the desulfurization absorption area and the gas oxidation area, and an isolation structure used for preventing denitration absorption liquid from being sprayed downwards to the gas oxidation area is arranged between the gas oxidation area and the denitration absorption area. Occupied space is small, treatment cost is low, and operation is safe and stable.

Description

Technical Field

[0001] This invention relates to the field of flue gas treatment technology, specifically to an integrated desulfurization and denitrification absorption tower and its usage method. Background Technology

[0002] The combustion of boilers in thermal power plants produces a large amount of gaseous pollutants such as nitrogen oxides and sulfur dioxide. The traditional removal method is to release ammonia into the flue gas. Nitrogen oxides and ammonia react with each other under the action of a catalyst to produce non-toxic nitrogen and water. At the same time, sulfur dioxide is removed by wet desulfurization equipment. However, the equipment has a complex structure, occupies a large space and is expensive. In operation, there are also problems such as excessive ammonia injection and ammonia escape causing blockage and corrosion of downstream equipment such as air preheaters and electrostatic precipitators, which affects the safe and stable operation of the equipment. Summary of the Invention

[0003] This invention provides an integrated desulfurization and denitrification absorption tower and its usage method to solve the problems of existing devices having complex structures, large space occupation, high processing costs, and poor safe and stable operation.

[0004] In a first aspect, the present invention provides an integrated desulfurization and denitrification absorption tower, wherein the following components are arranged sequentially from bottom to top inside the tower body:

[0005] The desulfurization absorption zone is equipped with a desulfurization absorption liquid pool and a desulfurization absorption liquid spraying device. The gas oxidation zone is equipped with an oxidant injection grid for spraying ozone, and multiple nozzles with a downward spray direction are evenly arranged on the oxidant injection grid. The denitrification absorption zone is equipped with a denitrification absorption liquid tank and a denitrification absorption liquid spraying device; The desulfurization absorption zone is equipped with a first demister between the gas oxidation zone and the denitrification absorption zone, and an isolation structure is provided between the gas oxidation zone and the denitrification absorption zone to prevent the denitrification absorption liquid from dripping into the gas oxidation zone.

[0006] Beneficial Effects: Using clean ozone as an oxidant to oxidize nitric oxide, ozone rapidly oxidizes nitric oxide in flue gas, which is difficult to absorb by alkaline solutions, into easily absorbed nitrogen dioxide. It completely replaces ammonia in traditional processes, thus eliminating the problems of air preheater blockage and corrosion, environmental safety risks, and increased operating costs caused by ammonia escape. The absorption tower of this application integrates multiple functional areas within a single tower body. Structurally, the step of nitric oxide oxidation using ozone is placed after the desulfurization step. This avoids the waste and ineffective consumption of ozone caused by the reaction of ozone with sulfur dioxide and the desulfurization absorbent, which occurs when the nitric oxide oxidation process in the flue gas occurs before the desulfurization step. Furthermore, through a demister and isolation structure, the various functional zones are separated, solving the problem of mutual interference between different process sections. This achieves the goal of efficiently, stably, and sequentially completing deep desulfurization and denitrification within a single tower body.

[0007] In one alternative embodiment, the oxidant injection grille is located above the first demister, and the vertical distance H between the grille and the upper surface of the first demister is 1.5 meters to 2.0 meters.

[0008] Beneficial effects: This distance provides ample counter-convective mixing space for the downward-sprayed ozone and rising flue gas, ensuring sufficient contact and complete reaction between ozone and nitric oxide. If the distance is too small, not only will mixing be insufficient, but gaseous oxidants may also enter the desulfurization absorption zone, interfering with the desulfurization process and leading to a decrease in oxidation efficiency. If the distance is too large, it will increase the ineffective height of the tower. This optimized distance achieves the best balance between ensuring high oxidation efficiency and controlling the tower height.

[0009] In one alternative embodiment, the absorption tower further includes an ozone generator connected to the oxidant injection grid via a pipe.

[0010] Beneficial effects: The modular arrangement of the ozone generator and its easy connection with the spray grid enable the immediate production and use of oxidant, making the system inside the absorption tower simple and reliable.

[0011] In one alternative embodiment, the isolation structure includes a liquid-blocking cap and a denitrification absorption liquid pool, the denitrification absorption liquid pool defining a flue gas passage, and the liquid-blocking cap being disposed above the flue gas passage, its horizontal projection completely covering the outlet of the flue gas passage.

[0012] Beneficial effects: The horizontal projection of the liquid-blocking cap completely covers the flue gas outlet below, which means that no matter how the denitrification absorbent is poured down, it will be completely received by this structure. No liquid can fall directly into the gas oxidation zone below, which physically ensures the "dryness" of the oxidation zone. On the one hand, it avoids the ineffective absorption of expensive ozone by alkaline solution, and on the other hand, it ensures the stable recovery of denitrification absorbent, thus guaranteeing the utilization rate and economy of the oxidant in the entire system.

[0013] In one optional embodiment, the denitrification absorption liquid pool is an annular liquid pool arranged around the central cylinder of the tower body; the liquid baffle is formed as a conical cover and fixed to the inner wall of the tower body.

[0014] Beneficial effects: The combination of the annular liquid pool and the central flue gas channel achieves a compact layout of the flue gas channel and the denitrification absorption liquid pool. Without increasing the tower diameter, it ensures the arrangement of the denitrification absorption liquid pool while providing a flue gas channel with a sufficiently large cross-sectional area for flue gas to pass through, thus ensuring the flue gas throughput.

[0015] In one optional embodiment, the atomized spray coverage of both the desulfurization absorbent spray device and the denitrification absorbent spray device is not less than 150%.

[0016] Beneficial effects: In other words, the atomized spraying areas of both the desulfurization absorbent spraying device and the denitrification absorbent spraying device overlap significantly, ensuring that a dense and uniform liquid curtain is formed across the entire cross-section of the tower after spraying. This greatly increases the contact area and probability between the gas and liquid phases, thereby enhancing the mass transfer process and achieving high removal efficiency.

[0017] In one alternative implementation, a second demister is also provided at the top of the denitrification absorption zone.

[0018] Beneficial effects: A second demister is installed at the top of the denitrification absorption zone to capture the denitrification absorption liquid droplets carried by the flue gas, ensuring the cleanliness of the final emitted flue gas, meeting the ultra-low emission standards, and preventing the droplets from corroding the flue gas flow downstream to the flue and chimney.

[0019] In one alternative embodiment, a flue gas inlet is provided on the side wall of the tower body, and the flue gas inlet is located above the design maximum liquid level line of the desulfurization absorption liquid pool.

[0020] Beneficial effects: Effectively prevents liquid in the desulfurization absorption pool from backflowing into the flue due to liquid level fluctuations or pressure changes within the tower. This ensures the dryness of the flue gas system inlet, avoids operational problems such as water carryover in the induced draft fan and flue corrosion, and improves the safety and reliability of the entire flue gas treatment system.

[0021] Secondly, the present invention also provides a flue gas desulfurization and denitrification method using the integrated desulfurization and denitrification absorption tower of the first aspect, comprising the following steps: Flue gas enters the desulfurization absorption zone and comes into countercurrent contact with the desulfurization absorption liquid to remove sulfur dioxide; After the desulfurized flue gas passes through the first demister to remove droplets, it enters the gas oxidation zone. In the gas oxidation zone, the downward-sprayed ozone mixes with the rising flue gas in a counter-current flow, oxidizing nitrogen oxides, mainly nitric oxide, in the flue gas into high-valence nitrogen oxides, mainly nitrogen dioxide. The oxidized flue gas bypasses the isolation structure and enters the denitrification absorption zone, where it comes into contact with the denitrification absorption liquid to remove nitrogen oxides. The purified flue gas is discharged from the top of the tower.

[0022] Beneficial effects: After desulfurization, ozone can oxidize only nitric oxide, improving oxidation efficiency and avoiding material waste and ineffective consumption of ozone. Through demisting and isolation, the three sub-processes of desulfurization, oxidation, and denitrification are spatially continuous yet independent, without interference between them. The downward-sprayed ozone in the oxidation zone creates strong turbulence in the area, resulting in good mixing between ozone and flue gas and ensuring a rapid and complete oxidation reaction.

[0023] In one alternative embodiment, the amount of ozone added is controlled according to the initial concentration of nitric oxide in the flue gas, and the molar ratio of ozone to nitric oxide is 1.0-1.5.

[0024] Beneficial effects: When the molar ratio of ozone to nitric oxide is 1, ozone can theoretically completely oxidize nitric oxide to nitrogen dioxide. In practice, choosing a ratio slightly higher than 1 can ensure that even with flue gas concentration fluctuations and uneven mixing, extremely high nitric oxide oxidation efficiency can still be achieved. At the same time, it avoids waste caused by excessive ozone and ozone residue in the exhaust gas, thus avoiding material waste. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of an absorption tower according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Tower body; 2. Desulfurization absorption liquid pool; 3. First pump body; 4. Second pump body; 5. Desulfurization absorption liquid spraying device; 6. First demister; 7. Oxidant spraying grid; 8. Denitrification absorption liquid pool; 9. Liquid baffle cap; 10. Denitrification absorption liquid spraying device; 11. Second demister; 12. Ozone generator. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The following is combined Figure 1 The following describes embodiments of the present invention.

[0030] According to an embodiment of the present invention, an integrated desulfurization and denitrification absorption tower is provided.

[0031] The combustion of boilers in thermal power plants produces a large amount of gaseous pollutants such as nitrogen oxides and sulfur dioxide. The traditional removal method is to release ammonia into the flue gas. Nitrogen oxides and ammonia react with each other under the action of a catalyst to produce non-toxic nitrogen and water. At the same time, sulfur dioxide is removed by wet desulfurization equipment. However, the equipment has a complex structure, occupies a large space and is expensive. In operation, there are also problems such as excessive ammonia injection and ammonia escape causing blockage and corrosion of downstream equipment such as air preheaters and electrostatic precipitators, which affects the safe and stable operation of the equipment.

[0032] Therefore, this application uses clean ozone as an oxidant to oxidize nitric oxide. Ozone can quickly oxidize nitric oxide in flue gas, which is not easily absorbed by alkaline solution, into easily absorbed nitrogen dioxide, replacing ammonia in the traditional process. This eliminates the problems of air preheater blockage and corrosion, environmental safety risks, and increased operating costs caused by ammonia escape.

[0033] In related technologies, when using ozone as an oxidant to treat flue gas, ozone is usually directly introduced into the flue gas to oxidize sulfur dioxide and nitrogen oxides. The oxidized flue gas is then subjected to desulfurization and denitrification treatment, or ozone and absorbent are simultaneously injected into the flue gas. However, this often results in ineffective reactions between ozone and the absorbent, or between ozone and sulfur dioxide, leading to material waste and significant ineffective ozone consumption, thus substantially increasing the cost of flue gas treatment.

[0034] To improve the oxidation efficiency of ozone as an oxidant and reduce flue gas treatment costs, this invention provides an integrated desulfurization and denitrification absorption tower. The tower body 1 contains, from bottom to top, a desulfurization absorption zone, a gas oxidation zone, and a denitrification absorption zone. This absorption tower integrates multiple functional zones within a single tower body 1, and structurally places the step of oxidizing nitric oxide with ozone after the desulfurization step. This avoids material waste and ineffective consumption of ozone caused by the reaction of ozone with sulfur dioxide and the desulfurization absorbent, thereby improving the oxidation efficiency of ozone as an oxidant.

[0035] Furthermore, the desulfurization absorption zone is equipped with a desulfurization absorption liquid pool 2 and a desulfurization absorption liquid spraying device 5. Since the atomizing nozzles of the desulfurization absorption liquid spraying device 5 are evenly distributed across the entire cross section of the tower body 1, the sprayed liquid surface can also evenly cover the entire cross section of the tower body 1. Therefore, the desulfurization absorption liquid sprayed by the desulfurization absorption liquid spraying device 5 can be fully mixed with the flue gas and fully absorb the sulfur dioxide in the flue gas flowing from bottom to top during the falling process.

[0036] The area through which the desulfurization absorbent falls from the desulfurization absorbent spray device 5 into the desulfurization absorbent pool 2 is the desulfurization absorption zone.

[0037] The denitrification absorption zone is equipped with a denitrification absorption liquid pool 8 and a denitrification absorption liquid spraying device 10. Since the atomizing nozzles of the denitrification absorption liquid spraying device 10 are evenly distributed across the entire cross section of the tower body 1, the sprayed liquid surface can also evenly cover the entire cross section of the tower body 1. Therefore, the sprayed denitrification absorption liquid can be fully mixed with the flue gas and fully absorb the nitrogen oxides in the flue gas during the falling process.

[0038] The area through which the denitrification absorption liquid falls from the denitrification absorption liquid spray device 10 to the denitrification absorption liquid pool 8 is the denitrification absorption zone.

[0039] Since the flue gas flows in the opposite direction to the liquid under the influence of gravity, the amount of contact between the flue gas and the absorbent liquid during the flue gas flow can be increased, thereby improving the removal efficiency.

[0040] The gas oxidation zone is equipped with an oxidant injection grid 7 for injecting ozone. Multiple nozzles with a downward injection direction are evenly arranged on the oxidant injection grid 7. The gas injected by the nozzles can evenly cover the entire cross section of the tower body 1. The ozone injected downward by the oxidant injection grid 7 can also be mixed with the rising flue gas in a counter-current flow, so that the injected ozone can be fully mixed with the flue gas, resulting in high mixing efficiency and a significant improvement in oxidation efficiency.

[0041] A first demister 6 is installed between the desulfurization absorption zone and the gas oxidation zone. The flue gas passes through the first demister 6 to remove the mist droplets formed by the desulfurization absorbent carried in the flue gas. As a result, the mist droplets formed by the desulfurization absorbent will not enter the gas oxidation zone and react with ozone, thus avoiding the waste and ineffective consumption of ozone caused by the reaction between ozone and the desulfurization absorbent, and improving the oxidation efficiency of ozone as an oxidant.

[0042] An isolation structure is provided between the gas oxidation zone and the denitrification absorption zone to prevent the denitrification absorption liquid from dripping into the gas oxidation zone. The isolation structure separates the denitrification absorption zone from the gas oxidation zone, which means that no liquid can fall directly from the upper denitrification absorption zone into the lower gas oxidation zone. This physically ensures the "dryness" of the gas oxidation zone and avoids the ineffective absorption of expensive ozone by the alkaline solution.

[0043] The first demister 6 and the isolation structure separate the various functional zones, solving the problem of mutual interference between different process sections, and enabling efficient, stable and sequential completion of deep desulfurization and denitrification within a single tower body 1.

[0044] In some embodiments, such as Figure 1As shown, the oxidant injection grille 7 is located above the first demister 6, and the vertical distance H between it and the upper surface of the first demister 6 is 1.5 meters to 2.0 meters. The distance between the oxidant injection grille 7 and the first demister 6 is not less than 1.5 meters, providing sufficient counter-convective mixing space for the downwardly injected ozone and the rising flue gas, ensuring that the ozone and nitric oxide are fully contacted and react completely. If the distance is too small, not only will the mixing be insufficient, but it may also cause the gaseous oxidant to enter the desulfurization absorption zone, causing interference with the desulfurization step and resulting in a decrease in oxidation efficiency. The distance between the oxidant injection grille 7 and the first demister 6 is not greater than 2 meters, avoiding increasing the ineffective height of the tower body 1.

[0045] In some embodiments, such as Figure 1 As shown, the absorption tower also includes an ozone generator 12 connected to the oxidant spray grid 7 via a pipeline. The ozone generator 12 is modularly arranged and easy to connect to the spray grid, realizing the immediate production and use of oxidant, making the system inside the absorption tower simple and reliable.

[0046] In some embodiments, such as Figure 1 As shown, the isolation structure includes a liquid-blocking cap 9 and a denitrification absorption liquid tank 8. The denitrification absorption liquid tank 8 defines the flue gas passage. The liquid-blocking cap 9 is located above the flue gas passage, and its horizontal projection completely covers the outlet of the flue gas passage. The horizontal projection of the liquid-blocking cap 9 completely covers the outlet of the flue gas passage below. This means that no matter how the denitrification absorption liquid is poured down, it will be completely received by the liquid-blocking cap 9. No liquid can fall directly into the gas oxidation zone below through the flue gas passage, which physically ensures the "dryness" of the oxidation zone. On the one hand, it avoids the ineffective absorption of expensive ozone by alkaline solution, and on the other hand, it ensures the stable recovery of the denitrification absorption liquid, thus guaranteeing the utilization rate and economy of the oxidant in the entire system.

[0047] The combination of the denitrification absorption liquid pool and the liquid baffle 9 covers the cross section of the tower body 1 on the horizontal plane, realizing the separation between the gas oxidation zone and the denitrification absorption zone. At the same time, the vertical spacing between the two reserves a channel for flue gas flow, ensuring the normal passage of flue gas.

[0048] Furthermore, the denitrification absorption liquid pool 8 itself is also constructed as part of the isolation structure, and the flue gas passage is defined by the denitrification absorption liquid pool, which simplifies the structure of the tower body 1 and reduces the production cost of the absorption tower.

[0049] In some embodiments, such as Figure 1 As shown, the denitrification absorption liquid pool 8 is an annular liquid pool arranged around the central cylinder of the tower body 1. The liquid baffle 9 is a conical cover or annular plate that matches the annular liquid pool. The cooperation between the annular liquid pool and the central flue gas channel realizes the compact layout of the flue gas channel and the denitrification absorption liquid pool 8. Without increasing the tower diameter, it ensures the arrangement of the denitrification absorption liquid pool 8 while providing a flue gas channel with a sufficiently large cross-sectional area for flue gas to pass through, thus ensuring the flue gas throughput.

[0050] Furthermore, the annular liquid pool structure forms a ring shape, resulting in uniform weight distribution. The weight can be directly transferred to tower body 1, which has a good weighing effect and can be set up more stably.

[0051] The diameter of the central cylinder of tower body 1 is not less than half the diameter of the corresponding tower body 1, so as to ensure that the flue gas passage defined by the central cylinder of tower body 1 has sufficient throughput to ensure that the flue gas passes through stably and efficiently.

[0052] The liquid-retaining cap 9 is formed as a conical shroud or annular plate that matches the annular liquid pool. Thus, the conical or inclined surface of the liquid-retaining cap 9 can smoothly guide the received liquid back to the annular liquid pool, achieving self-recirculation of the liquid without the need for additional power. Furthermore, the structure of the conical shroud or annular plate provides low resistance to the rising flue gas, which helps ensure a uniform distribution of the flue gas flow field inside the tower body 1, facilitating subsequent denitrification reactions.

[0053] In other embodiments, the flue gas passage may include multiple passages that are uniformly or non-uniformly arranged, and the liquid baffle 9 can be correspondingly arranged above the flue gas passage. The design can be customized as needed and is not limited here.

[0054] The desulfurization absorbent spray device 5 is connected to the desulfurization absorbent tank 2 via a first pump body 3, and the desulfurization absorbent tank 2 circulates desulfurization absorbent to the desulfurization absorbent spray device 5 through the first pump body 3. The denitrification absorbent tank 8 is connected to the denitrification absorbent spray device 10 via a second pump body 4, and the denitrification absorbent tank 8 circulates denitrification absorbent to the denitrification absorbent spray device 10 through the second pump body 4.

[0055] In some embodiments, such as Figure 1 As shown, the atomized spray coverage of both the desulfurization absorbent spray device 5 and the denitrification absorbent spray device 10 is no less than 150%. This means that the atomized spray areas of both devices overlap significantly, ensuring that a dense and uniform liquid curtain is formed across the entire cross-section of the tower body 1 after spraying. This greatly increases the contact area and probability between the gas and liquid phases, thereby enhancing the mass transfer process and achieving high removal efficiency.

[0056] In some embodiments, such as Figure 1 As shown, a second demister 11 is also provided at the top of the denitrification absorption zone. The second demister 11 is installed at the top of the denitrification absorption zone to capture the denitrification absorption liquid droplets carried by the flue gas, ensuring the cleanliness of the final emitted flue gas, meeting the ultra-low emission standards, and preventing the droplets from corroding the flue gas flow downstream to the flue and chimney.

[0057] The first demister 6 and the second demister 11 can be independently selected from one or more of plate, tube, or ridge demisters. Selecting mature and reliable plate, tube, or ridge demisters for the first demister 6 and the second demister 11 ensures demisting efficiency and long-term system stability while facilitating maintenance and replacement.

[0058] In some embodiments, such as Figure 1 As shown, a flue gas inlet is provided on the side wall of the tower body 1. The flue gas inlet is located above the design maximum liquid level line of the desulfurization absorption liquid pool 2 to prevent the liquid in the desulfurization absorption liquid pool 2 from backflowing into the flue due to liquid level fluctuations or pressure changes inside the tower.

[0059] The flue gas inlet is located below the desulfurization absorbent spray device 5, and there is a certain height difference between the two to ensure that the flue gas can be evenly diffused at the bottom of the tower body 1 and then fully contact the desulfurization absorbent during the upward flow to remove sulfur dioxide.

[0060] According to an embodiment of the present invention, in another aspect, a flue gas desulfurization and denitrification method using an integrated desulfurization and denitrification absorption tower is also provided, comprising the following steps: S1, flue gas enters the desulfurization absorption zone and comes into countercurrent contact with the desulfurization absorption liquid to remove sulfur dioxide.

[0061] Specifically, flue gas enters the desulfurization absorption zone through the inlet on the side wall of tower 1; the desulfurization absorption liquid forms an atomized liquid curtain and is sprayed downward through the desulfurization absorption liquid spraying device 5. The spray coverage of the desulfurization absorption liquid spraying device 5 is not less than 150%. During the process of passing through the desulfurization absorption zone, the sulfur dioxide in the flue gas undergoes a chemical reaction with the desulfurization absorption liquid to generate sulfite or sulfate, thereby achieving efficient removal of sulfur dioxide.

[0062] S2, after the flue gas after desulfurization is removed by the first demister 6 to remove droplets, it enters the gas oxidation zone. In the gas oxidation zone, the downward-sprayed ozone mixes with the rising flue gas in a counter-current flow, oxidizing the nitrogen oxides in the flue gas, which are mainly composed of nitric oxide, into high-valence nitrogen oxides, which are mainly composed of nitrogen dioxide.

[0063] Specifically, after large-diameter droplets are removed by the first demister 6, the dried desulfurized flue gas, having lost its desulfurization absorbent and sulfur dioxide, enters the gas oxidation zone. Ozone is injected downwards at a certain initial velocity through the oxidant injection grid 7 located at a certain distance above the first demister 6, creating an ozone-rich atmosphere in the entire gas oxidation zone. The ozone is supplied by the ozone generator 12. The downwardly injected ozone mixes intensely with the rising dried desulfurized flue gas in a turbulent flow. Nitrogen monoxide in the flue gas undergoes an oxidation reaction with ozone within milliseconds, generating easily absorbed nitrogen dioxide.

[0064] Since most of the nitrogen oxides in the flue gas produced by thermal power generation are nitric oxide, which is not easily absorbed, ozone can be used as a gaseous oxidant. The flue gas enters the gas oxidation zone and is oxidized by ozone, transforming into nitrogen dioxide, which is easily absorbed.

[0065] In some embodiments, the ozone dosage is controlled based on the initial concentration of nitric oxide in the flue gas, and the molar ratio of ozone to nitric oxide is 1.0-1.5. When the molar ratio of ozone to nitric oxide is 1, theoretically, ozone can completely oxidize nitric oxide to nitrogen dioxide. In practice, a ratio slightly higher than 1 is chosen to ensure that even with flue gas concentration fluctuations and uneven mixing, extremely high nitric oxide oxidation efficiency can still be achieved, while avoiding waste caused by excessive ozone and ozone residue in the exhaust gas, thus preventing material waste.

[0066] S3, the oxidized flue gas bypasses the isolation structure and enters the denitrification absorption zone, where it comes into contact with the denitrification absorption liquid to remove nitrogen oxides.

[0067] The oxidized flue gas continues to flow upwards, changing direction below the isolation structure. Specifically, the oxidized flue gas first contacts the bottom structure of the denitrification absorption liquid tank, and under its guidance, flows upwards along the flue gas channel defined by the denitrification absorption liquid tank until it reaches the baffle cap 9. The diameter of the baffle cap 9 is larger than the diameter of the flue gas channel defined by the denitrification absorption liquid tank, and it is spaced apart from the denitrification absorption liquid tank 8 above it. The flue gas enters the denitrification absorption zone through the channel formed by the vertical gap between the edge of the baffle cap 9 and the denitrification absorption liquid tank. In the denitrification absorption zone, the alkaline denitrification absorption liquid is sprayed from top to bottom, contacting the rising nitrogen dioxide-rich flue gas, undergoing absorption and disproportionation reactions to generate nitrite and nitrate, achieving efficient removal of nitrogen oxides. The baffle cap 9, formed in a cone shape, completely covers the flue gas channel below in its horizontal projection, effectively blocking the downward flow of the denitrification absorption liquid, while guiding the denitrification absorption liquid received above it to the denitrification absorption liquid tank.

[0068] S4, the purified flue gas is discharged through the top of the tower.

[0069] Specifically, the denitrified flue gas passes through the second demister 11 located at the top of the denitrification absorption zone to further remove the mist droplets entrained with the denitrification absorption liquid, ensuring the cleanliness of the flue gas; finally, the flue gas that meets the ultra-low emission standards is discharged from the top outlet of the tower.

[0070] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined in this application.

Claims

1. An integrated desulfurization and denitrification absorption tower, characterized in that, The absorption tower contains, from bottom to top, the following components: The desulfurization absorption zone is equipped with a desulfurization absorption liquid pool and a desulfurization absorption liquid spraying device. The gas oxidation zone is equipped with an oxidant spray grid for spraying ozone, and multiple nozzles with a downward spray direction are evenly arranged on the oxidant spray grid. The denitrification absorption zone is equipped with a denitrification absorption liquid tank and a denitrification absorption liquid spraying device; A first demister is provided between the desulfurization absorption zone and the gas oxidation zone, and an isolation structure is provided between the gas oxidation zone and the denitrification absorption zone to prevent the denitrification absorption liquid from dripping into the gas oxidation zone.

2. The integrated desulfurization and denitrification absorption tower according to claim 1, characterized in that, The oxidant injection grille is located above the first demister, and the vertical distance H between it and the upper surface of the first demister is 1.5 meters to 2.0 meters.

3. The integrated desulfurization and denitrification absorption tower according to claim 1, characterized in that, It also includes an ozone generator connected to the oxidant spray grid via a pipe.

4. The integrated desulfurization and denitrification absorption tower according to claim 1, characterized in that, The isolation structure includes a liquid-blocking cap and a denitrification absorption liquid pool. The denitrification absorption liquid pool defines a flue gas passage. The liquid-blocking cap is disposed above the flue gas passage, and its horizontal projection completely covers the outlet of the flue gas passage.

5. The integrated desulfurization and denitrification absorption tower according to claim 4, characterized in that, The denitrification absorption liquid pool is an annular liquid pool arranged around the central cylinder of the tower body; the liquid baffle is formed into a conical cover and fixed to the inner wall of the tower body.

6. The integrated desulfurization and denitrification absorption tower according to claim 1, characterized in that, The atomized spray coverage of both the desulfurization absorbent spray device and the denitrification absorbent spray device is not less than 150%.

7. The integrated desulfurization and denitrification absorption tower according to claim 1, characterized in that, A second demister is also provided at the top of the denitrification absorption zone.

8. The integrated desulfurization and denitrification absorption tower according to claim 1, characterized in that, A flue gas inlet is provided on the side wall of the tower body, and the flue gas inlet is located above the design maximum liquid level line of the desulfurization absorption liquid pool.

9. A method for flue gas desulfurization and denitrification using an integrated desulfurization and denitrification absorption tower according to any one of claims 1 to 8, characterized in that, Includes the following steps: Flue gas enters the desulfurization absorption zone and comes into countercurrent contact with the desulfurization absorption liquid to remove sulfur dioxide; After the desulfurized flue gas passes through the first demister to remove droplets, it enters the gas oxidation zone. In the gas oxidation zone, the downward-sprayed ozone mixes with the rising flue gas in a counter-current flow, oxidizing nitrogen oxides, mainly nitric oxide, in the flue gas into high-valence nitrogen oxides, mainly nitrogen dioxide. The oxidized flue gas bypasses the isolation structure and enters the denitrification absorption zone, where it comes into contact with the denitrification absorption liquid to remove nitrogen oxides. The purified flue gas is discharged from the top of the tower.

10. The flue gas desulfurization and denitrification method according to claim 9, characterized in that, The amount of ozone added is controlled according to the initial concentration of nitric oxide in the flue gas, and the molar ratio of ozone to nitric oxide is 1.0-1.5.

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