A device for denitration ammonia injection self-enhanced mixing and an ammonia injection system comprising the same

Abstract

The utility model discloses a kind of denitration ammonia injection self-rotating reinforced mixing device and the ammonia injection system comprising it, denitration ammonia injection self-rotating reinforced mixing device, including first ammonia injection pipe, second ammonia injection pipe, first deflector and second deflector;The number of second ammonia injection pipe is three or more, the import of each second ammonia injection pipe is communicated with the export of first ammonia injection pipe;Each second ammonia injection pipe corresponds a first deflector and a second deflector;First deflector is arc plate structure, and second deflector is flat plate structure;First deflector one end is connected on the lateral wall of corresponding second ammonia injection pipe export end, and the export of corresponding second ammonia injection pipe is not blocked, the concave surface of first deflector is towards the export of corresponding second ammonia injection pipe, and each first deflector is arranged in propeller type in circumferential direction;Second deflector is connected on corresponding first deflector.The above-mentioned device can form automatically rotating flow disturbance at ammonia injection export, and the uniformity of ammonia-nitrogen mixture is significantly enhanced, without additionally adding static mixer.

Description

Technical Field

[0001] This utility model relates to a device for spin-enhanced mixing of denitrification ammonia spray and an ammonia spraying system including the device, belonging to the field of spin ammonia spraying technology. Background Technology

[0002] Large coal-fired power plants commonly use SCR (Selective Catalytic Reduction) denitrification devices to reduce NOx emission concentrations in flue gas. SCR utilizes the reduction properties of NH3 on NOx, reducing it to environmentally harmless N2 and H2O under the action of a catalyst. In actual operation, controlling the amount of ammonia injected is particularly critical. This requires both reasonable control of the total ammonia injection and ensuring uniformity of ammonia injection (mainly referring to a relatively uniform ammonia-to-nitrogen molar ratio) to ensure that NOx emission concentrations meet standards within the allowable ammonia slip range.

[0003] DL / T296-2011, "Technical Guidelines for Flue Gas Denitrification in Thermal Power Plants," stipulates that "the inlet velocity deviation of the SCR denitrification device should be within ±15%, the absolute temperature deviation should not exceed 10℃, and the deviation of the ammonia-nitrogen molar ratio should be within ±10%." However, in reality, due to frequent changes in domestic boiler combustion methods and coal types, as well as limited on-site layout space, the technical requirements stipulated in the above industry standards are difficult to meet under current technological conditions.

[0004] Under the policy background of deep peak shaving and wide-load denitrification of coal-fired boilers, the operating conditions faced by denitrification units are becoming increasingly complex. For example, significant changes in the opening of the temperature regulating damper in the tail shaft flue cause substantial changes in the inlet velocity field, temperature field, and NOx concentration field of the SCR denitrification unit. When the SCR ammonia injection distribution lacks online adjustment or sufficiently fine online adjustment capabilities, it is easy to cause local ammonia-nitrogen molar ratios to be far below the average value, and even exceed 1.0, resulting in reduced denitrification efficiency and increased ammonia slip rate. Uneven temperature field at low loads may also cause local temperatures to fall below the allowable ammonia injection temperature. If ammonia injection continues, it will further clog the micropores of the denitrification catalyst, and in severe cases, cause deactivation.

[0005] As reported in patent application CN202323583929.5 (titled "A SCR Denitrification Catalytic Device for a Stove Combustion Furnace"), some SCR denitrification devices have installed various types of static mixers downstream of the ammonia injection section to enhance the uniformity of ammonia-nitrogen mixing. However, traditional mixers can only generate small-scale eddies, which have a certain effect on improving the uniformity of the ammonia-nitrogen molar ratio, but have little effect on improving the uniformity of the flow field and temperature field. Therefore, this application proposes a device for spin-enhanced mixing of ammonia injection for denitrification, which eliminates the need for an additional static mixer. Through structural improvements, a swirling disturbance is automatically formed at the ammonia injection outlet, significantly enhancing the uniformity of ammonia-nitrogen mixing. Summary of the Invention

[0006] This invention provides a device for spin-enhanced mixing of ammonia spray in denitrification and an ammonia spraying system including the device. It can automatically generate swirling disturbance at the ammonia spraying outlet, which significantly enhances the uniformity of ammonia-nitrogen mixing without the need for an additional static mixer.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A device for denitrification ammonia injection with spin-enhanced mixing includes a first ammonia injection pipe, a second ammonia injection pipe, a first guide plate, and a second guide plate; There are three or more second ammonia injection pipes, and the inlet of each second ammonia injection pipe is connected to the outlet of the first ammonia injection pipe. Each second ammonia injection pipe corresponds to a first guide plate and a second guide plate; the first guide plate has an arc plate structure, and the second guide plate has a flat plate structure; one end of the first guide plate is connected to the side wall of the outlet end of the corresponding second ammonia injection pipe, the first guide plate will not block the outlet of the corresponding second ammonia injection pipe, and the concave surface of the first guide plate faces the outlet of the corresponding second ammonia injection pipe, and the first guide plates are arranged in a propeller-like manner in the circumferential direction; the second guide plate is connected to the corresponding first guide plate.

[0008] The number of the second ammonia injection pipe, the first guide plate, and the second guide plate mentioned above are equal and correspond one-to-one.

[0009] Each ammonia injection pipe has an inlet at one end and an outlet at the other. The direction from the inlet to the outlet is also the direction of material flow inside the pipe.

[0010] The aforementioned first guide vanes are arranged in a propeller-like manner in the circumferential direction, similar to the arrangement of fan blades.

[0011] During use, ammonia passes through the first ammonia injection pipe and the second ammonia injection pipe in sequence, and then is sprayed onto the first guide plate. Under the guidance of the first and second guide plates, it forms an enhanced swirling disturbance on the surrounding flue gas, causing the ammonia and flue gas to mix in a swirling manner, thereby significantly enhancing the uniformity of the mixture between the sprayed ammonia and NOx in the flue gas.

[0012] The combination of the first guide plate with the arc plate structure and the second guide plate with the flat plate structure has a synergistic effect of enhancing the swirling disturbance. The ammonia sprayed on the concave surface of the first guide plate forms a swirling flow, while the second guide plate blocks and enhances the swirling flow, thus enhancing the swirling disturbance of the surrounding flue gas, thereby making the sprayed ammonia and NOx in the flue gas mix evenly.

[0013] To improve the swirling mixing effect, the first guide plate is long and narrow, with one end connected to the outlet sidewall of the corresponding second ammonia injection pipe and the other end being free; the second guide plate is connected to the side of the corresponding first guide plate.

[0014] The length direction of the first guide vane is the direction from one end to the other; the sides of the first guide vane refer to the two sides along its length. When the first guide vane is rectangular, the two sides are its long sides.

[0015] As one of the preferred implementations, the first guide vane is a rectangle with an arc-shaped structure in the length direction, the angle between the length direction of the first guide vane and the horizontal plane is 15~45°, and the angle between the width direction of the first guide vane and the horizontal plane is 70~85°.

[0016] To further enhance the mixing effect of ammonia and nitrogen, the bottom side of the first guide plate is welded along the length direction to the upper surface of the second guide plate. In use, the upper surface of the second guide plate faces away from the mainstream flue gas (mainstream flue gas), and the lower surface faces the mainstream flue gas. That is, the upper surface of the second guide plate is the side facing away from the airflow, and the lower surface is the side facing the airflow.

[0017] In order to increase the mixing space and improve the mixing effect, the outlet end of the second ammonia injection pipe has a sloping structure with one end longer and the other end shorter (that is, one end of the outlet end is longer or higher than the other end, where the longer or higher end is the long end and the other end is the short end). One end of the first guide plate is connected to the side wall of the corresponding long end of the outlet end of the second ammonia injection pipe.

[0018] Further preferably, the angle between the plane at the outlet end of the second ammonia injection pipe and the axial direction of the second ammonia injection pipe is 25-60°.

[0019] To reduce the risk of pipe blockage, the angle between the axis of the second ammonia injection pipe and the horizontal plane is 15-45°, and the inlet end of the second ammonia injection pipe is higher than the outlet end. This allows dust and other contaminants inside the pipe to be easily carried out under the influence of gravity and ammonia flow, thus effectively reducing or preventing blockage.

[0020] The aforementioned second ammonia injection pipes are evenly distributed around the outlet of the first ammonia injection pipe.

[0021] To better ensure the swirling mixing effect, there are 5-6 second ammonia injection pipes. Correspondingly, there are also 5-6 first and second guide vanes each.

[0022] An ammonia injection system includes the aforementioned denitrification ammonia injection spin-enhanced mixing device, and further includes an ammonia injection header and an ammonia injection delivery pipe; the ammonia injection header is located outside the vertical flue at the inlet of the denitrification unit; There are three or more ammonia injection pipes. The inlet of each ammonia injection pipe is connected to the main ammonia injection pipe. The outlet of each ammonia injection pipe extends into a vertical flue and bends vertically downwards (i.e., the outlet of the ammonia injection pipe is vertically downwards). At the outlet end of each ammonia injection pipe, 4-5 denitrification ammonia injection spin-enhanced mixing devices are evenly distributed around the perimeter. That is, the denitrification ammonia injection spin-enhanced mixing devices are located within the vertical flue. The inlet of the first ammonia injection pipe of each denitrification ammonia injection spin-enhanced mixing device is connected to the outlet of its corresponding ammonia injection pipe; the outlet end of the first ammonia injection pipe has a vertically downward bend. The outlet end of the first ammonia injection pipe is vertically downward; the angle between the axis of the second ammonia injection pipe and the horizontal plane is 15~45°, and the inlet end of the second ammonia injection pipe is higher than the outlet end. That is, from the inlet to the outlet, the second ammonia injection pipe is inclined downward. Under the action of gravity and ammonia gas flow, dust and other particles in the pipe can be carried out, thereby effectively reducing or preventing blockage. The inner diameters of the ammonia injection main pipe, ammonia injection delivery pipe, first ammonia injection pipe and second ammonia injection pipe decrease in sequence, which can accelerate the flow of ammonia gas flow. While ensuring the mixing effect with flue gas, more dust can be carried out to better ensure the anti-blocking effect.

[0023] Control valves can be installed on the ammonia injection pipeline outside the flue as needed to control the amount of ammonia injected in each zone.

[0024] During operation, ammonia gas enters the ammonia injection delivery pipe from the main ammonia injection pipe, passes through the first and second ammonia injection pipes in sequence, and is ejected from the outlet of the second ammonia injection pipe. Under the combined action of the first guide plate with an arc plate structure and the second guide plate with a flat plate structure, a strong swirling flow is formed, which disturbs the surrounding flue gas, thereby making the flue gas and ammonia gas mix quickly and evenly, significantly improving the uniformity of the ammonia-nitrogen molar ratio, and also significantly improving the uniformity of the flow velocity field and temperature field of the first layer of denitrification catalyst cross section.

[0025] Any technologies not mentioned in this utility model are based on existing technologies.

[0026] This invention relates to a device for enhancing the swirling mixing of ammonia sprayed for denitrification. By combining a first guide plate with an arc-shaped structure and a second guide plate with a flat structure, the device synergistically enhances the swirling disturbance. Ammonia sprayed onto the concave surface of the first guide plate forms a swirling flow, while the second guide plate, through obstruction and swirling enhancement, further enhances the swirling disturbance of the surrounding flue gas. This results in uniform mixing of the sprayed ammonia and NOx in the flue gas, significantly improving the uniformity of the flow field, temperature field, and ammonia-nitrogen molar ratio of the first-layer denitrification catalyst cross-section, thus improving the denitrification effect. The device is simple in structure, easy to modify and prepare, and easy to promote. Attached Figure Description

[0027] Figure 1 Schematic diagram of a device for enhancing ammonia spinning during denitrification. Figure 1 (Anti-spin); Figure 2 for Figure 1 Top view; Figure 3 Schematic diagram of a device for enhancing ammonia spinning during denitrification. Figure 2 (sine rotation); Figure 4 for Figure 3 Top view; Figure 5 Schematic diagram of a device for enhancing ammonia spinning during denitrification. Figure 3 (Anti-spin); Figure 6 for Figure 5 Top view; Figure 7 Schematic diagram of a device for enhancing ammonia spinning during denitrification. Figure 4 (sine rotation); Figure 8 for Figure 7 Top view; In the diagram, 1 is the first ammonia injection pipe, 2 is the second ammonia injection pipe, 3 is the first guide plate, and 4 is the second guide plate. Detailed Implementation

[0028] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments. Example 1

[0029] like Figure 1-2 As shown, a device for spin-enhanced mixing of denitrification ammonia injection includes a first ammonia injection pipe, a second ammonia injection pipe, a first guide plate, and a second guide plate; There are three or more second ammonia injection pipes, and the inlet of each second ammonia injection pipe is connected to the outlet of the first ammonia injection pipe. Each second ammonia injection pipe corresponds to a first guide plate and a second guide plate; the first guide plate has an arc plate structure, and the second guide plate has a flat plate structure; one end of the first guide plate is connected to the side wall of the outlet end of the corresponding second ammonia injection pipe, the first guide plate will not block the outlet of the corresponding second ammonia injection pipe, and the concave surface of the first guide plate faces the outlet of the corresponding second ammonia injection pipe, and the first guide plates are arranged in a propeller-like manner in the circumferential direction; the second guide plate is connected to the corresponding first guide plate.

[0030] During use, ammonia passes through the first ammonia injection pipe and the second ammonia injection pipe in sequence, and then is sprayed onto the first guide plate. Under the guidance of the first and second guide plates, it forms an enhanced swirling disturbance on the surrounding flue gas, causing the ammonia and flue gas to mix in a swirling manner, thereby significantly enhancing the uniformity of the mixture between the sprayed ammonia and NOx in the flue gas. Example 2

[0031] Based on Example 1, the following improvements were made: In order to improve the swirling mixing effect, the first guide plate is long and narrow, with one end of the first guide plate connected to the outlet side wall of the corresponding second ammonia injection pipe and the other end being a free end; the second guide plate is connected to the side of the corresponding first guide plate. Example 3

[0032] Based on Example 2, the following improvements were made: the first guide plate is a rectangle with an arc-shaped structure along its length. The angle between the length direction of the first guide plate and the horizontal plane is 15° (or 20°, 25°, etc.), and the angle between the width direction of the first guide plate and the horizontal plane is 75° (or 80°, 85°, etc.). To further enhance the mixing effect of ammonia and nitrogen, the bottom side of the first guide plate is welded along its length to the upper surface of the second guide plate. In use, the upper surface of the second guide plate faces away from the mainstream flue gas (mainstream flue gas), and the lower surface faces the mainstream flue gas; that is, the upper surface of the second guide plate is the side facing away from the airflow, and the lower surface is the side facing the airflow. Figure 1-2 As shown, the first and second guide vanes are arranged in a counter-propeller configuration. Alternatively, they could be arranged as follows: Figure 3-4 The arrangement is a forward propeller shape. (Example) Figure 5-8 As shown, the first guide vane can also be a long trapezoid with an arc-shaped structure along its length. Example 4

[0033] Based on Example 3, the following improvements were made: To increase the mixing space and improve the mixing effect, the outlet end of the second ammonia injection pipe has a sloping structure with one end longer than the other (i.e., one end of the outlet end is longer or higher than the other end, where the longer or higher end is the long end and the other end is the short end). One end of the first guide plate is connected to the side wall of the corresponding long end of the outlet end of the second ammonia injection pipe. In this example, the angle between the plane where the outlet end of the second ammonia injection pipe is located and the axial direction of the second ammonia injection pipe is 35° (it can also be 40°, 45°, etc.). Example 5

[0034] Based on Example 4, the following improvements were made: To reduce the risk of pipe blockage, the angle between the axial direction of the second ammonia injection pipe and the horizontal plane is 15° (it can also be 20°, 25°, etc.), and the inlet end of the second ammonia injection pipe is higher than the outlet end. This facilitates the removal of dust and other contaminants from the pipe under the influence of gravity and ammonia flow, thereby effectively reducing or preventing blockage. There are six second ammonia injection pipes, and correspondingly six first and six second guide plates, with each second ammonia injection pipe evenly distributed around the outlet of the first ammonia injection pipe.

[0035] An ammonia injection system includes the aforementioned denitrification ammonia injection spin-enhanced mixing device, and further includes an ammonia injection header and an ammonia injection delivery pipe; the ammonia injection header is located outside the vertical flue at the inlet of the denitrification unit; There are three or more ammonia injection pipes. The inlet of each ammonia injection pipe is connected to the main ammonia injection pipe. The outlet of each ammonia injection pipe extends into a vertical flue and bends vertically downwards (i.e., the outlet of the ammonia injection pipe is vertically downwards). Four denitrification ammonia injection spin-enhanced mixing devices are evenly distributed around the outlet end of each ammonia injection pipe. These devices are located within the vertical flue. The inlet of the first ammonia injection pipe of each denitrification ammonia injection spin-enhanced mixing device is connected to the outlet of its respective ammonia injection pipe. The outlet end of the first ammonia injection pipe has a vertically downward bend. The outlet end of the first ammonia injection pipe is vertically downward; the angle between the axis of the second ammonia injection pipe and the horizontal plane is 15°, and the inlet end of the second ammonia injection pipe is higher than the outlet end. That is, from the inlet to the outlet, the second ammonia injection pipe is inclined downward. Under the action of gravity and ammonia gas flow, dust and other particles in the pipe can be carried out, thereby effectively reducing or preventing blockage. The inner diameters of the ammonia injection main pipe, ammonia injection delivery pipe, first ammonia injection pipe and second ammonia injection pipe decrease in sequence, which can accelerate the flow of ammonia gas flow. While ensuring the mixing effect with flue gas, more dust can be carried out to better ensure the anti-blocking effect.

[0036] A control valve is installed on the ammonia injection delivery pipe outside the flue to control the ammonia injection rate in each zone. During operation, ammonia gas enters the ammonia injection delivery pipe from the main ammonia injection pipe, passes through the first and second ammonia injection pipes in sequence, and is ejected from the outlet of the second ammonia injection pipe. Under the combined action of the first guide plate with an arc plate structure and the second guide plate with a flat plate structure, a strong swirling flow is formed, which disturbs the surrounding flue gas. This allows the flue gas and ammonia gas to mix quickly and evenly, significantly improving the uniformity of the ammonia-nitrogen molar ratio. At the same time, it also significantly improves the uniformity of the flow velocity field and temperature field of the first layer of denitrification catalyst cross section.

[0037] The above-described denitrification ammonia injection spin-enhanced mixing devices, through the combination of a first guide plate with an arc plate structure and a second guide plate with a flat plate structure, achieve a synergistic effect of enhancing swirling disturbance. Ammonia sprayed on the concave surface of the first guide plate forms a swirling flow, while the obstruction and swirling enhancement of the second guide plate enhance the swirling disturbance of the surrounding flue gas. This results in uniform mixing of the sprayed ammonia and NOx in the flue gas, significantly improving the uniformity of the flow field, temperature field, and ammonia-nitrogen molar ratio of the first-layer denitrification catalyst cross-section, and improving the denitrification effect. The device has a simple structure, is easy to modify and prepare, and is easy to promote.

Claims

1. A device for spin-enhanced mixing of ammonia sprayed during denitrification, characterized in that: Includes a first ammonia injection pipe, a second ammonia injection pipe, a first guide plate, and a second guide plate; There are three or more second ammonia injection pipes, and the inlet of each second ammonia injection pipe is connected to the outlet of the first ammonia injection pipe. Each second ammonia injection pipe corresponds to a first guide plate and a second guide plate; the first guide plate has an arc plate structure and the second guide plate has a flat plate structure; one end of the first guide plate is connected to the side wall of the outlet end of the corresponding second ammonia injection pipe. The first guide plate will not block the outlet of the corresponding second ammonia injection pipe, and the concave surface of the first guide plate faces the outlet of the corresponding second ammonia injection pipe. Each first guide plate is arranged in a propeller-like manner in the circumferential direction. The second guide plate is connected to the corresponding first guide plate.

2. The device for denitration ammonia injection spin enhancement hybridization according to claim 1, characterized in that: The first guide plate is long and narrow, with one end connected to the outlet sidewall of the corresponding second ammonia injection pipe along its length and the other end being free. The second guide plate is connected to the side of the corresponding first guide plate.

3. The device for denitration ammonia injection spin enhancement hybridization according to claim 1 or 2, characterized in that: The first guide vane is a rectangle with an arc-shaped structure along its length. The angle between the length direction of the first guide vane and the horizontal plane is 15~45°, and the angle between the width direction of the first guide vane and the horizontal plane is 70~85°.

4. The device for spin-enhanced mixing of denitrified ammonia spray according to claim 3, characterized in that: The bottom side of the first guide plate is welded along its length to the upper surface of the second guide plate.

5. The device for spin-enhanced mixing of denitrified ammonia spray according to claim 1 or 2, characterized in that: The outlet end of the second ammonia injection pipe has a sloping structure with one end longer than the other. One end of the first guide plate is connected to the side wall of the longer end of the outlet end of the corresponding second ammonia injection pipe.

6. The device for denitration ammonia injection and spin enhancement mixing of claim 5, wherein: The angle between the plane at the outlet end of the second ammonia injection pipe and the axial direction of the second ammonia injection pipe is 25-60°.

7. The device for spin-enhanced mixing of denitrified ammonia spray according to claim 1 or 2, characterized in that: The angle between the axis of the second ammonia injection pipe and the horizontal plane is 15~45°, and the inlet end of the second ammonia injection pipe is higher than the outlet end.

8. The device for spin-enhanced mixing of denitrified ammonia spray according to claim 1 or 2, characterized in that: Each of the second ammonia injection pipes is evenly distributed around the outlet of the first ammonia injection pipe.

9. The device for denitration ammonia injection spin enhancement hybridization according to claim 1 or 2, characterized in that: The number of second ammonia injection pipes is 5-6.

10. An ammonia injection system comprising the device for denitration ammonia injection and spin-enhanced mixing of any one of claims 1-9, characterized in that: It also includes the ammonia injection header and the ammonia injection delivery pipe; the ammonia injection header is located outside the vertical flue at the inlet of the denitrification unit; There are three or more ammonia injection pipes. The inlet of each ammonia injection pipe is connected to the main ammonia injection pipe. The outlet of each ammonia injection pipe extends into the vertical flue and bends vertically downward. At the outlet end of each ammonia injection pipe, 4-5 denitrification ammonia injection spin-enhanced mixing devices are evenly distributed around the perimeter. The inlet of the first ammonia injection pipe of the denitrification ammonia injection spin-enhanced mixing device is connected to the outlet of the ammonia injection pipe it belongs to. The outlet end of the first ammonia injection pipe has a vertical downward bend. The angle between the axis of the second ammonia injection pipe and the horizontal plane is 15-45°, and the inlet end of the second ammonia injection pipe is higher than the outlet end. The inner diameters of the main ammonia injection pipe, the ammonia injection pipe, the first ammonia injection pipe, and the second ammonia injection pipe decrease sequentially.

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