CN206325403U - A kind of efficient SCR reactors of flaring entrance - Google Patents

Abstract

A high-efficiency SCR reactor with a gradually expanding inlet section belongs to the internal structure of the SCR denitrification reactor. The reactor is composed of an inlet section, a main section and an outlet section, and the overall structure of the reactor is symmetrical; the inlet section of the reactor adopts a gradually expanding form, that is, the cross section of the connecting section between the flue and the main body of the reactor gradually expands. At least 3 layers of deflectors are required at the reactor inlet, that is, 1#~3#, and 4# deflectors or more can be added. 1# deflector is located on the upper part of the reactor inlet section, and its top is in contact with the interface between the reactor inlet section and the flue; 2# and 3# deflectors are located in the middle of the reactor inlet section. 2# and 3# deflectors are the key equipment of this reactor, which are composed of multiple pairs of deflectors at the same height, and the arrangement directions of 2# and 3# deflectors are perpendicular to each other. The reactor can meet the technical index requirements of the flow field (CV value is less than 15%) by adjusting 1# to 3# deflectors.

Description

A high-efficiency SCR reactor with gradually expanding inlet section

technical field

The utility model relates to the internal structure of an SCR denitrification reactor with a gradually expanding inlet section (the cross section of the connecting section between the flue and the reactor main body gradually expands), in particular to a structure and a deflector of the inlet section of the SCR denitrification reactor form and arrangement.

Background technique

SCR is an efficient flue gas denitrification technology, which is widely used in the denitrification treatment of boilers, kilns and other industrial facilities that generate a large amount of nitrogen oxides. The denitrification efficiency of SCR technology is affected by many factors, among which the flow field distribution is one of the most important technical indicators. The assessment surface for the uniformity of the flow field distribution is the cross-section at 0.5m upstream of the surface of the first layer of catalyst, and the maximum deviation coefficient (CV) of the flue gas velocity distribution at this section is required to be ≤15%. The definition of CV is:

in:

average value

Vi: sampled value

N: number of sampling points

The flue gas flow rate inside the SCR reactor is relatively high, and is affected by the dust content. In order to avoid the deposition of dust, the flue gas usually goes vertically upward from the vertical flue, then enters the top area of the reactor through the horizontal flue, and then flows downward. After passing through the rectifier and catalyst, it is finally discharged from the reactor outlet. The flue gas inlet is usually arranged perpendicular to the reactor body. The schematic diagram of a conventional reactor is shown in Figure 1. It can be seen that in order to ensure a uniform flow field, the width H of the general reactor inlet section is the width H of the reactor main body, and the reactor inlet section is horizontally arranged, and the vertically arranged reactor main body At a 90° angle. After passing through the deflector and rectifier, the flue gas completes a 90-degree turn and forms a relatively uniform velocity distribution. The optimization of this type of reactor only needs to adjust the distribution of the airflow in the X direction by adding a deflector.

However, in some special cases, the inlet section of the reactor cannot be arranged horizontally, but in a gradually expanding form, as shown in Figure 2. It is characterized in that the flue gas inlet section and the reactor main body are in the same vertical direction, the width H1 of the reactor inlet section in the X direction gradually expands to H2, and the width H3 in the Y direction gradually expands to H4. That is to say, it is necessary to adjust the speed distribution in the X and Y directions at the same time to meet the technical index requirements. The form and arrangement of conventional deflectors cannot meet the fluid distribution index requirements.

The design and optimization process of the deflector is complicated. If the design is not proper, the flow field index of the reactor will not meet the requirements, and it will also bring a great risk of wear and tear. The design and optimization of the deflector usually takes a long time, and often becomes one of the important factors affecting the progress of the project. Therefore, it is particularly urgent to develop a high-efficiency SCR reactor with a gradually expanding inlet section.

Contents of the invention

The purpose of this utility model is to solve the above problems, using advanced CFD software star-ccm+, combined with physical model testing, to design a kind of high-efficiency SCR reactor with gradually expanding inlet section, the schematic diagram is shown in Figure 2. 1. A gradual A high-efficiency SCR reactor with an enlarged inlet section. The reactor is composed of an inlet section, a main section and an outlet section. The reactor has a symmetrical structure as a whole. It is characterized in that:

The inlet section of the reactor adopts the form of gradual expansion, that is, the cross section of the connecting section between the flue and the main body of the reactor gradually expands;

There are at least 3 layers of deflectors at the reactor inlet, that is, 1# to 3#, and the 1# deflector is located on the upper part of the reactor inlet section, and its top is connected to the interface between the reactor inlet section and the flue;

2# and 3# deflectors are located in the middle of the inlet section of the reactor, and are composed of multiple pairs of deflectors at the same height. The arrangement directions of 2# and 3# deflectors are perpendicular to each other; Figure 8 layout.

2. Furthermore, the minimum distance between each pair of deflectors for 2# and 3# deflectors is H12, the minimum distance between two pairs of deflectors is H11, and the cross-sectional width of the deflectors is H10, 0<H11<2H10 , 0<H12<2H10.

3. Furthermore, B is the angle between the 2# deflector and the vertical direction, and C is the angle between the 3# deflector and the vertical direction; 5°<B≤45°, 5°<C≤45°.

4. Further, a certain installation distance H7 should be reserved between 2# and 3# deflectors, 0<H7≤50mm.

5. Further, in the side view of the reactor, the angle between the hypotenuse and the vertical direction is E; in the front view of the reactor, the angle between the hypotenuse and the vertical direction is F; when F is 0°, that is, the front view of the inlet section is When it is rectangular, only set 2# deflector, or set both 2# and 3# deflector.

6. Further, a 4# deflector is also provided, and the 4# deflector is located at the lower part of the reactor inlet section. The height H9 between the bottom of the 4# deflector and the rectifier is the reserved installation height, 0<H9≤50mm.

8. Further, add deflectors at any position between 1# and 2#, 3# and 4#; when adding deflectors, it is necessary to set an inclined part to evenly distribute the flow velocity, and the angle between the inclined part and the vertical direction is A and D, A and D do not exceed 60°.

The CFD software numerical simulation process mainly uses the following models:

(1) Gas phase turbulence model

a) Continuity equation:

b) The momentum equation in the X direction:

c) The momentum equation in the Y direction:

d) The momentum equation in the Z direction:

e) K equation:

f) ε equation:

Among them, the turbulent viscosity coefficient p is the fluid pressure; ρ is the gas density; the turbulence generation item G _k is:

The above differential equation can be written in the following general form:

Among them, φ is the dependent variable, Γ _φ is the diffusion coefficient of the dependent variable φ, and S _φ is the corresponding source item in the conservation equation of the dependent variable.

Expressed in a unified transport equation form:

The terms in the formula are convection term, diffusion term and source term from left to right.

(2) Porous media model

For the pressure drop of the catalyst layer in the SCR reactor, the simulation is carried out by considering the catalyst layer as a porous medium. The pressure drop loss simulation formula is as follows:

In the formula, Si—momentum source term in i direction, Pa/m; μ—flow dynamic viscosity, Pa s; α—medium permeability; vi—velocity component in i direction, m/s; ρ—density, kg/m ³ ; C ₂ —internal resistance factor, 1/m.

The setting of the physical model is defined by dimensionless fluid characteristic quantities, including Reynolds number, Euler number, Bass number, Fourier number, and model geometric ratio values.

The main contents of the utility model include: (1) The reactor is composed of an inlet section, a main section and an outlet section, and the overall reactor has a symmetrical structure; (2) The inlet section of the reactor adopts a gradually expanding form, that is, the flue and the reactor The cross-section of the connecting section of the main body gradually expands. Among them, in the side view, the angle between the hypotenuse and the vertical direction is E; in the front view, the angle between the hypotenuse and the vertical direction is F; (3) At least 3 layers of deflectors must be set at the reactor inlet, that is, 1#～ 3#, add 4# guide plate according to the specific situation. (4) 2# and 3# deflectors are the key equipment of this invention, which are composed of multiple pairs of deflectors located at the same height, and the arrangement directions of 2# and 3# deflectors are perpendicular to each other (2# deflectors The plates are arranged along the Y direction, and the 3# deflector is arranged along the X direction). The section of each pair of deflectors is arranged in a figure-eight shape, the minimum distance between each pair of deflectors is H12, the minimum distance between two pairs of deflectors is H11, and the cross-sectional width of the deflectors is H10, 0<H11<2H10, 0<H12<2H10. B is the angle between the 2# deflector and the vertical direction, and C is the angle between the 3# deflector and the vertical direction. 5°<B≤45°, 5°<C≤45°. 2# and 3# deflectors are located close to 1/2 of the height of the diverging section, that is, H6≈H8≈(1/2)H5. A certain installation distance should be reserved between 2# and 3# deflectors H7, 0<H7≤50mm. If F is 0°, that is, when the front view of the inlet section is rectangular, only 2# guide plate can be set.

(5) 1#, 4# deflectors are the auxiliary equipment of this invention. According to the situation, only the 1# deflector can be installed; the 1# deflector is located on the upper part of the reactor inlet section, and its top is in contact with the interface between the reactor inlet section and the flue. The 4# deflector is located at the lower part of the reactor inlet section, and its bottom is above the interface between the reactor inlet section and the reactor main section.

It is also possible to add deflectors at any position between 1# and 2#, 3# and 4# according to specific conditions (need to achieve a more uniform flow field distribution effect). The form of the deflector can be varied, but the inclined part must be set to distribute the flow velocity evenly, and the angle between it and the vertical direction is A and D, and A and D generally do not exceed 60°.

The utility model can realize the following functions:

By adjusting the deflectors 1# to 4#, the technical index requirements of the flow field can be met (CV value is less than 15%), see Figure 11 and Figure 12.

Description of drawings

Fig. 1 is a schematic structural diagram of a traditional SCR reactor.

Fig. 2 is a structural schematic diagram of the SCR reactor of the present invention.

Fig. 3 is a schematic diagram of the arrangement of the inlet section of the SCR reactor and the guide plate of the utility model.

Fig. 4 is the perspective view of the inlet section of the SCR reactor and the deflector of the utility model (a corresponds to 1#, 2#, 4# deflector, b corresponds to 1#, 3#, 4# deflector, c Corresponding to 1#, 2#, 3#, 4# guide plate).

Fig. 5 is a diagram of the overall flow velocity distribution inside the traditional SCR reactor (no flue deflector, CV=34%).

Fig. 6 is a flow velocity distribution diagram upstream of the catalyst in a traditional SCR reactor (no flue deflector, CV=34%).

Fig. 7 is a diagram of the overall flow velocity distribution inside the traditional SCR reactor (the flue guide plate is set, CV=15%).

Fig. 8 is a flow velocity distribution diagram upstream of the catalyst in a traditional SCR reactor (with a flue deflector, CV=15%).

Fig. 9 is a distribution diagram of the overall flow velocity inside the SCR reactor of the present invention (no flue deflector, CV=33%).

Fig. 10 is a flow velocity distribution diagram upstream of the catalyst of the SCR reactor of the present invention (no flue deflector, CV=33%).

Fig. 11 is a distribution diagram of the overall flow velocity inside the SCR reactor of the present invention (the flue deflector is set, CV=8.3%).

Fig. 12 is a flow velocity distribution diagram upstream of the catalyst of the SCR reactor of the present invention (the flue deflector is set, CV=8.3%).

detailed description

Below in conjunction with accompanying drawing and specific embodiment the utility model is further described.

The reactor is composed of an inlet section, a main section and an outlet section, and the whole reactor has a symmetrical structure.

The inlet section of the reactor adopts the form of gradual expansion, that is, the cross section of the connecting section between the flue and the main body of the reactor gradually expands. Wherein, in the side view, the angle between the hypotenuse and the vertical direction is E; in the front view, the angle between the hypotenuse and the vertical direction is F.

At least 3 layers of deflectors should be set at the reactor inlet, that is, 1#~3#, and 4# deflectors should be added according to the specific situation.

2# and 3# deflectors are the key equipment of this invention, they are composed of multiple pairs of deflectors at the same height, and the arrangement directions of 2# and 3# deflectors are perpendicular to each other (2# deflectors are along direction, 3# deflector is arranged along X direction). The section of each pair of deflectors is arranged in a figure-eight shape, the minimum distance between each pair of deflectors is H12, the minimum distance between two pairs of deflectors is H11, and the cross-sectional width of the deflectors is H10, 0<H11<2H10, 0<H12<2H10. B is the angle between the 2# deflector and the vertical direction, and C is the angle between the 3# deflector and the vertical direction. 5°<B≤45°, 5°<C≤45°. 2# and 3# deflectors are located close to 1/2 of the height of the diverging section, that is, H6≈H8≈(1/2)H5. A certain installation distance should be reserved between 2# and 3# deflectors H7, 0<H7≤50mm. If F is 0°, that is, when the front view of the inlet section is rectangular, only 2# guide plate can be set.

1#, 4# deflectors are the auxiliary equipment of this invention. According to the situation, only the 1# deflector can be installed; the 1# deflector is located on the upper part of the reactor inlet section, and its top is in contact with the interface between the reactor inlet section and the flue. The 4# deflector is located at the lower part of the reactor inlet section, and its bottom is above the interface between the reactor inlet section and the reactor main section.

It is also possible to add deflectors at any position between 1# and 2#, 3# and 4# according to specific conditions (need to achieve a more uniform flow field distribution effect). The form of the deflector can be varied, but the inclined part must be set to distribute the flow velocity evenly, and the angle between it and the vertical direction is A and D, and A and D generally do not exceed 60°.

Further, the height between the bottom of the 4# deflector plate and the rectifier, that is, H9, is the reserved installation height, and 0<H9≤50mm.

The specific embodiment of the utility model is as follows:

(1) Reactor parameters

The reactor is composed of an inlet section, a main section and an outlet section, and the overall reactor has a symmetrical structure;

The gas velocity in the cross-section of the reactor should be controlled below 6m/s.

There is no limit to the amount of gas handled.

(2) Parameters of the reactor inlet section

The inlet section of the reactor adopts the form of gradual expansion, that is, the cross section of the connecting section between the flue and the main body of the reactor gradually expands. Wherein, in the side view, the angle between the hypotenuse and the vertical direction is E; in the front view, the angle between the hypotenuse and the vertical direction is F; at least one of E and F is not 0°. E≤45°, F≤45°.

(3) Parameters of deflector in the inlet section of the reactor

At least 3 layers of deflectors should be set at the reactor inlet, that is, 1#~3#, and 4# deflectors should be added according to the specific situation.

2# and 3# deflectors are the key equipment of this invention, they are composed of multiple pairs of deflectors at the same height, and the arrangement directions of 2# and 3# deflectors are perpendicular to each other (2# deflectors are along direction, 3# deflector is arranged along X direction). The section of each pair of deflectors is arranged in a figure-eight shape, the minimum distance between each pair of deflectors is H12, the minimum distance between two pairs of deflectors is H11, and the cross-sectional width of the deflectors is H10, 0<H11<2H10, 0<H12<2H10. B is the angle between the 2# deflector and the vertical direction, and C is the angle between the 3# deflector and the vertical direction. 5°<B≤45°, 5°<C≤45°. 2# and 3# deflectors are located close to 1/2 of the height of the diverging section, that is, H6≈H8≈(1/2)H5. A certain installation distance should be reserved between 2# and 3# deflectors H7, 0<H7≤50mm. If F is 0°, that is, when the front view of the inlet section is rectangular, only 2# guide plate can be set.

1#, 4# deflectors are the auxiliary equipment of this invention. According to the situation, only the 1# deflector can be installed; the 1# deflector is located on the upper part of the reactor inlet section, and its top is in contact with the interface between the reactor inlet section and the flue. The 4# deflector is located at the lower part of the reactor inlet section, and its bottom is above the interface between the reactor inlet section and the reactor main section.

It is also possible to add deflectors at any position between 1# and 2#, 3# and 4# according to specific conditions (need to achieve a more uniform flow field distribution effect). The form of the deflector can be varied, but the inclined part must be set to distribute the flow velocity evenly, and the angle between it and the vertical direction is A and D, and A and D generally do not exceed 60°.

By adjusting 1# to 4# deflectors, the flow field index requirements of the SCR reactor can be met.

The flue gas volume is 600,000 Nm ³ /h, the cross-sectional gas velocity is 4.2m/s, E is 15°, F is 6°, A is 6°～25°, B is 20°, C is 15°, D It is 7°～20°, H7=50mm, and CV is 8.3%.

The flue gas volume is 200,000 Nm ³ /h, the cross-sectional gas velocity is 4.0m/s, E is 11°, F is 0°, A is 0°～9°, B is 20°, no 3# diversion is set Plate, D is 0°～7°, H7=30mm, CV is 11.0%.

Claims (8)

1. A kind of high-efficiency SCR reactor of gradually expanding inlet section, reactor is made of inlet section, main body section and outlet section, and reactor overall is symmetrical structure, is characterized in that: The inlet section of the reactor adopts the form of gradual expansion, that is, the cross section of the connecting section between the flue and the main body of the reactor gradually expands; There are at least 3 layers of deflectors at the reactor inlet, that is, 1# to 3#, and the 1# deflector is located on the upper part of the reactor inlet section, and its top is connected to the interface between the reactor inlet section and the flue; 2# and 3# deflectors are located in the middle of the inlet section of the reactor, and are composed of multiple pairs of deflectors at the same height. The arrangement directions of 2# and 3# deflectors are perpendicular to each other; Figure 8 layout. 2. A kind of high-efficiency SCR reactor of gradual expansion inlet section according to claim 1, is characterized in that: The minimum distance between each pair of deflectors for 2# and 3# deflectors is H12, the minimum distance between two pairs of deflectors is H11, and the cross-sectional width of the deflectors is H10, 0<H11<2H10, 0<H12 <2H10. 3. A kind of high-efficiency SCR reactor with gradually expanding inlet section according to claim 1, characterized in that: B is the angle between the 2# deflector and the vertical direction, C is the angle between the 3# deflector and the vertical direction; 5°<B≤45°, 5°<C≤45°. 4. A kind of high-efficiency SCR reactor with gradually expanding inlet section according to claim 1, characterized in that: A certain installation distance H7 should be reserved between 2# and 3# deflectors, 0<H7≤50mm. 5. The high-efficiency SCR reactor of a kind of gradual expansion entrance section according to claim 1, is characterized in that: In the side view of the reactor, the angle between the hypotenuse and the vertical direction is E; in the front view of the reactor, the angle between the hypotenuse and the vertical direction is F; when F is 0°, that is, when the front view of the inlet section is a rectangle, only Set 2# deflector, or set both 2# and 3# deflector. 6. The high-efficiency SCR reactor of a kind of gradual expansion entrance section according to claim 1, is characterized in that: A 4# deflector is also provided, and the 4# deflector is located at the lower part of the reactor inlet section. 7. A high-efficiency SCR reactor with gradually expanding inlet section according to claim 6, characterized in that: the height H9 between the bottom of the 4# deflector plate and the rectifier is the reserved installation height, 0<H9≤50mm. 8. The high-efficiency SCR reactor of a kind of gradual expansion entrance section according to claim 1, is characterized in that: Add a deflector at any position between 1# and 2#, 3# and 4#; when adding a deflector, you must set an inclined part to distribute the flow velocity evenly. The angle between the inclined part and the vertical direction is A and D, A and D does not exceed 60°.