Circulating fluidized bed SCR (Selective Catalytic Reduction) denitration inlet flue device applying flow field simulation optimization

Abstract

The utility model relates to a circulating fluidized bed SCR (Selective Catalytic Reduction) denitration inlet flue device applying flow field simulation optimization, which is used for solving the problem of velocity distribution uniformity of an SCR denitration inlet flow field, and belongs to the field of circulating fluidized bed boiler flue gas treatment. The device comprises the diffusion flue, the horizontal flue, the corner flue, the first flow guide plate and the second flow guide plate, through CFD flow field simulation optimization, the structure parameters of the flue device, such as the included angle and the distance between the flow guide plates, are determined so as to achieve optimal flue gas flow field distribution, and the device is simple and reasonable in design, has a good flow equalizing effect, and is suitable for large-scale popularization and application. According to the device, the SCR denitration efficiency can be improved, nitrogen oxide emission can be reduced, the environmental protection requirement is met, meanwhile, the device hardly increases system resistance, the overall layout of the boiler is not affected, the problems of thermal stress and fly ash deposition are considered, the service life of a flue is prolonged, and the use requirement is met.

Description

Technical Field

[0001] The utility model relates to an inlet flue device, in particular to a circulating fluidized bed SCR denitration inlet flue device using flow field simulation optimization, which is used to solve the problem of uniformity of velocity distribution of the SCR denitration inlet flow field and belongs to the field of circulating fluidized bed boiler flue gas treatment. Background Art

[0002] Boiler flue gas contains a large amount of harmful gases such as sulfur dioxide and nitrogen oxides. If these gases are discharged into the atmosphere, they will cause environmental problems such as acid rain and photochemical smog. With the increasing attention paid by the country to environmental protection in recent years, various localities have successively issued ultra-clean emission standards. It is difficult to ensure that nitrogen oxide emissions meet the standards by combustion alone. By introducing SCR denitrification technology, enterprises can effectively reduce NOx emissions, ensure that their production processes comply with environmental protection regulations, and reduce negative impacts on the environment. In order to improve the production efficiency of the SCR denitrification device, it is determined that the uniformity of the flow field velocity distribution of the SCR denitrification inlet flue gas must be improved. After comprehensive inquiries into the patent system and the daily design of daily technicians, the flue before entering the SCR denitrification device often adopts a wedge-shaped (triangular) structure, and the design of the guide plate is designed along the direction of the flue gas flow. However, the flow field simulation is often not ideal.

[0003] Therefore, it is particularly necessary to design an SCR denitrification inlet flue device with a reasonable structure and solve the existing technical problems. Utility Model Content

[0004] The purpose of the utility model is to overcome the above-mentioned deficiencies in the prior art and to provide a circulating fluidized bed SCR denitrification inlet flue device which has a simple and reasonable structural design, is safe and reliable, has a good flow balancing effect, allows the flue gas to naturally turn 90 degrees, and has a reasonable flue gas velocity distribution and is optimized by flow field simulation.

[0005] The technical solution adopted by the utility model to solve the above-mentioned problem is: a circulating fluidized bed SCR denitrification inlet flue device using flow field simulation optimization includes a diffusion flue, a horizontal flue and a corner flue, a horizontal flue is arranged on one side of the diffusion flue, and the other end of the horizontal flue is connected to the corner flue, characterized in that it also includes a first guide plate and a second guide plate, the diffusion flue extends upward, and the angle with the horizontal is 50°-60°, the horizontal flue is arranged horizontally, and the first guide plate and the second guide plate are arranged at the corner position of the flue gas flow direction.

[0006] Preferably, the initial angle between the diffusion flue of the utility model and the horizontal is set to 55°.

[0007] Preferably, the corner flue of the present invention is arranged at an initial angle of 45° to the horizontal.

[0008] Preferably, the spacing arrangement between the first guide plate and the second guide plate of the utility model has a vertical deviation of 50-150 mm and a horizontal deviation of 250-350 mm.

[0009] Preferably, a rectifying grid is provided at the inlet of the SCR denitration device of the utility model, the bar spacing of the rectifying grid is 100-120 mm, and the height of the rectifying grid is 100-500 mm.

[0010] Compared with the prior art, the utility model has the following advantages and effects: 1) The overall structural design is simple and reasonable, and after flow field simulation optimization, it meets the temperature uniformity and velocity uniformity requirements of the inlet flue gas of the SCR denitrification device; 2) The structure of the flue device hardly increases the system resistance, so as not to affect the overall layout of the overall boiler; 3) The design of the flue device takes into account the stress temperature that may be caused by the guide plate. Since it is arranged inside the flue and is consistent with the thermal deformation of the flue, there will be no large thermal stress; 4) The design of the guide plate takes into account the deposition of fly ash. According to the current design, it will not cause large-scale fly ash deposition and will not shorten the life of the flue. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of an embodiment of the utility model.

[0012] Figure 2 This is a vector diagram of the velocity distribution in the cross section of the inlet flue device of the circulating fluidized bed SCR denitrification of the utility model.

[0013] Figure 3 This is the temperature distribution diagram of the cross section of the inlet flue device of the circulating fluidized bed SCR denitrification of the utility model.

[0014] In the figure: diffusion flue 1, horizontal flue 2, corner flue 3, first guide plate 4, second guide plate 5, flue gas flow direction F. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are provided to explain the present invention, but the present invention is not limited to the following examples.

[0016] Example

[0017] See also Figures 1 to 3The utility model uses flow field simulation optimization to optimize the circulating fluidized bed SCR denitrification inlet flue device, which includes a diffusion flue 1, a horizontal flue 2, a corner flue 3, a first guide plate 4 and a second guide plate 5. The diffusion flue 1 includes a front side plate (not shown in the figure), a rear side plate and an upwardly inclined top cover plate. The angle between the top cover plate and the horizontal plane is 50-60°. The initial angle during implementation is 55°, which is determined according to the CFD simulation calculation results.

[0018] A horizontal flue 2 is arranged on the side next to the diffusion flue 1. The other end of the horizontal flue 2 is connected to a corner flue 3. The corner flue 3 is generally arranged at 45 degrees.

[0019] In this embodiment, the diffusion flue 1 allows the smoke to diffuse quickly and reduce the smoke velocity; the horizontal flue 2 allows the smoke to be fully mixed and improves the uniformity; the corner flue 3 allows the smoke to be turned 90 degrees;

[0020] In this embodiment, the first guide plate 4 and the second guide plate 5 are arranged at the corner position of the flue gas flow direction F; the first guide plate 4 and the second guide plate 5 make the flue gas with abnormal flow velocity make a hard turn, thereby changing the flue gas flow direction F.

[0021] In this embodiment, the spacing arrangement of the first guide plate 4 and the second guide plate 5 is determined after flow field simulation optimization, and the initial setting is that the vertical deviation of each other is 100 mm and the horizontal deviation is 300 mm.

[0022] The inlet of the SCR denitrification device is generally equipped with a rectifier grid, the bar spacing of the rectifier grid is 100-120mm, and the height of the rectifier grid is 100-500mm.

[0023] When this embodiment is working, the flue gas in the flue is evenly distributed and then completely mixed with ammonia in the SCR denitration device shown in the figure to undergo denitration treatment under the action of a catalyst.

[0024] In practical applications, according to the specific parameters of the boiler and the flue gas characteristics, the structural parameters of the flue device can be further optimized through flow field simulation, such as the angle between the diffusion flue and the horizontal flue, the angle of the corner flue, and the spacing of the guide plates, so as to achieve the best flue gas flow field distribution effect.

[0025] The design of this embodiment can effectively improve the uniformity of the velocity distribution of the inlet flue gas flow field of the SCR denitrification device, thereby improving the SCR denitrification efficiency, reducing nitrogen oxide emissions, and meeting environmental protection requirements. At the same time, the flue device has a simple and reasonable structure, is easy to implement and maintain, and has good application prospects.

[0026] The implementation results are as follows:

[0027] In the SCR flue gas denitrification inlet flue of the above-mentioned embodiment example, the flue gas inlet adopts the flow outlet boundary condition of the economizer front section (not shown in the figure) as the flow inlet boundary condition of this section. The flow inlet boundary condition of the economizer front section is a flue gas flow velocity of 5m / s and a temperature setting of 440°C, both of which are perpendicular to the inlet surface. Such initial boundary condition settings are more in line with actual flue gas conditions.

[0028] like Figure 2-Figure 3 As shown, Figure 2 The letter on the current line (a, b, c, d, e, f) is the smoke speed of the point on the current line. For example, a on the line means that all points on the line have speed a; Figure 3 The letter (g, h) on the current line is the smoke temperature of the point on the current line. For example, g on the line means that all points on the line have temperature g.

[0029] CFD simulation calculations were performed using software: simulation results show that the utility model evenly mixes the flue gas before the SCR denitrification device, with a velocity uniformity index greater than 85% and an absolute temperature difference less than 10°C; at the same time, the flue gas entering the SCR flue gas denitrification reactor is evenly distributed in the flow equalization section, and the flow direction of the flue gas passing through the rectifier grid is made vertically downward (not shown in the figure), thereby improving the catalyst reaction efficiency and catalyst utilization, while avoiding blockage and deactivation caused by erosion of the catalyst wall by solid particles.

[0030] Through the above description, those skilled in the art can already implement it.

[0031] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the utility model. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the utility model are included in the protection scope of the utility model patent. Technicians in the technical field of the utility model can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the protection scope of the utility model.

Claims

1. A circulating fluidized bed SCR denitrification inlet flue device using flow field simulation optimization, comprising a diffusion flue (1), a horizontal flue (2) and a corner flue (3), wherein the diffusion flue (1) is provided with a horizontal flue (2) on one side, and the other end of the horizontal flue (2) is connected to the corner flue (3), characterized in that: It also comprises a first guide plate (4) and a second guide plate (5), the diffusion flue (1) extends upwards, with an angle of 50°-60° with the horizontal, the horizontal flue (2) is arranged horizontally, and the first guide plate (4) and the second guide plate (5) are arranged at a corner position of the flue gas flow direction.

2. The circulating fluidized bed SCR denitrification inlet flue device using flow field simulation optimization according to claim 1 is characterized in that: The initial angle between the diffusion flue (1) and the horizontal is set to 55°.

3. The circulating fluidized bed SCR denitrification inlet flue device using flow field simulation optimization according to claim 1 is characterized in that: The corner flue (3) is arranged at an initial angle of 45° to the horizontal.

4. The circulating fluidized bed SCR denitrification inlet flue device using flow field simulation optimization according to claim 1 is characterized in that: The spacing between the first guide plate (4) and the second guide plate (5) is arranged such that the vertical deviation is 50-150 mm and the horizontal deviation is 250-350 mm.

5. The circulating fluidized bed SCR denitrification inlet flue device using flow field simulation optimization according to claim 1 is characterized in that: A rectifying grid is provided at the inlet of the SCR denitration device. The bar spacing of the rectifying grid is 100-120 mm, and the height of the rectifying grid is 100-500 mm.

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