CN112452147A - SCR denitration system internal structure and design method thereof - Google Patents
SCR denitration system internal structure and design method thereof Download PDFInfo
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- CN112452147A CN112452147A CN202011198544.5A CN202011198544A CN112452147A CN 112452147 A CN112452147 A CN 112452147A CN 202011198544 A CN202011198544 A CN 202011198544A CN 112452147 A CN112452147 A CN 112452147A
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- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
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Abstract
The invention relates to an internal structure of an SCR (selective catalytic reduction) denitration system and a design method thereof, wherein the internal structure comprises a flue gas inlet end and a flue gas outlet end which are connected through a first horizontal channel, a first vertical channel, a second horizontal channel and a second vertical channel, an ammonia spraying grid, a mixer, a rectifying grid and a catalyst bed layer are sequentially arranged between the flue gas inlet end and the flue gas outlet end, a first flow guide device is arranged in the first horizontal channel, a second flow guide device is arranged at a first straight bending position, a third flow guide device is arranged at the second straight bending position, a fourth flow guide device is arranged at the third straight bending position, the rectifying grid is arranged between the fourth flow guide device and the catalyst bed layer, the fourth flow guide device comprises a plurality of arc-shaped flow guide plates which are same in size and are distributed at equal intervals, and flow guide holes. Compared with the prior art, the invention can optimize the flow direction of the flue gas, improve the flue gas distribution uniformity of the upper layer of the catalyst bed, avoid the catalyst bed from being subjected to local excessive erosion and improve the denitration efficiency.
Description
Technical Field
The invention relates to the technical field of denitration of coal-fired power plants, in particular to an internal structure of an SCR (selective catalytic reduction) denitration system and a design method thereof.
Background
SCR selective catalytic reduction denitration technique is widely applied to large-scale coal fired power plant's production process, and SCR denitrification facility has that the denitration rate is high, the technique is more mature and do not have characteristics such as secondary pollution to the environment, has the factor of decisive influence to denitration efficiency among the SCR denitrification facility, including factors such as the mixed effect of flue gas flow field, reductant and the temperature field that distributes, and these factors can produce the influence to denitration facility's long-term safe and stable operation.
In the denitration device adopted at present, NH generally exists3The problem of non-uniform distribution of the concentration field and velocity field, which results in different degrees of catalyst attrition and a reduction in denitration efficiency. The application of the guide plate has the effects of enhancing the uniformity of a flow field, improving the flow direction of flue gas and the like, so that the part of the flow field above the catalyst bed layer is uniform. On one hand, the removal efficiency of NOx can be ensured, on the other hand, the local speed of the flue gas is reduced, the erosion of a catalyst bed layer is reduced, and the service life of the catalyst is prolonged.
Through searching the prior art, the current guide plate is arranged and mainly arranged by changing the arrangement position of the guide plate, although partial flow field can be improved, the problem that the flue gas is gathered at the side close to the flue still exists after the actual operation after the installation, so that the flue gas flow field in the area between the upper part of the catalyst bed layer and the guide plate has large speed deviation, the catalyst bed layer is subjected to local excessive erosion, the service life of the catalyst is influenced, and the denitration efficiency is reduced.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide an internal structure of an SCR denitration system and a design method thereof.
The purpose of the invention can be realized by the following technical scheme: an internal structure of an SCR (selective catalytic reduction) denitration system comprises a flue gas inlet end and a flue gas outlet end, wherein an ammonia spraying grid, a mixer, a rectification grid and a catalyst bed layer are sequentially arranged between the flue gas inlet end and the flue gas outlet end, the flue gas inlet end is connected to the flue gas outlet end through a first horizontal channel, a first vertical channel, a second horizontal channel and a second vertical channel, the first horizontal channel is connected with the first vertical channel through a first straight bend, the first vertical channel is connected to the second horizontal channel through a second straight bend, the second horizontal channel is connected to the second vertical channel through a third straight bend, and the second vertical channel is connected with the flue gas outlet end;
install first guiding device in the first horizontal passage, first bending position installs the second guiding device always, spout ammonia grid and blender and all install in first vertical passageway, the blender is located the top of spouting the ammonia grid, the third guiding device is installed to the second bending position always, the fourth guiding device is installed to the third bending position always, rectification grid and catalyst bed are all installed in the vertical passageway of second, the rectification grid is located between fourth guiding device and the catalyst bed, fourth guiding device includes the polylith arc guide plate that the size is the same and equidistant distribution, the water conservancy diversion hole has been seted up on the arc guide plate.
Further, the arc radius of arc guide plate is 600mm, and the arc angle is 90.
Furthermore, the upper end of the arc-shaped guide plate is connected with a horizontal straight plate, and the lower end of the arc-shaped guide plate is connected with a vertical tail wing.
Further, the length of the horizontal straight plate is 100mm, and the length of the vertical tail wing is 500 mm.
Furthermore, a plurality of equidistant flow guide holes are formed in the arc-shaped flow guide plate.
Further, the diameter of the diversion hole is 60 mm.
Further, the arc-shaped guide plate is made of high-temperature-resistant materials.
Further, the first flow guiding device comprises a plurality of parallel flow guiding plates which are parallel to each other in the vertical direction.
A method for designing an internal structure of an SCR denitration system comprises the following steps:
s1, constructing a simulation model corresponding to the internal structure of the SCR denitration system, wherein at the moment, no flow guide hole is formed in each of a plurality of arc-shaped plates of the fourth flow guide device, obtaining flow field distribution of flue gas in a region between a catalyst bed layer and the fourth flow guide device through numerical simulation, and determining an initial flue gas speed deviation value;
s2, for the fourth flow guide device, sequentially and equidistantly arranging flow guide holes on the first arc-shaped flow guide plate close to the inner side of the third straight bend, and sequentially obtaining the flow field distribution of the flue gas in the area between the catalyst bed layer and the fourth flow guide device through numerical simulation to obtain a plurality of corresponding flue gas speed deviation values, wherein if the plurality of flue gas speed deviation values have data smaller than or equal to a preset deviation value, the arrangement scheme of the flow guide holes corresponding to the flue gas speed deviation values is the optimization scheme of the internal structure, otherwise, the step S3 is continuously executed;
and S3, for the fourth flow guide device, sequentially forming flow guide holes at equal intervals on each arc-shaped flow guide plate from the second arc-shaped flow guide plate close to the inner side of the third straight bend, sequentially obtaining a plurality of corresponding flue gas speed deviation values through numerical simulation, and forming a flow guide hole forming scheme corresponding to the flue gas speed deviation value until the flue gas speed deviation value with the numerical value smaller than or equal to the preset deviation value is obtained, namely, the optimization scheme of the internal structure is obtained.
Further, the preset deviation value is specifically 15%.
Compared with the prior art, the invention has the following advantages:
according to the invention, the arc-shaped guide plate above the rectifying grid in the internal structure of the SCR denitration system is punched, and the guide holes are mainly formed in the arc-shaped guide plate close to the inner side of the third straight bend, so that high-speed flue gas on the front side of a flue can be effectively dispersed, the windward side of the guide holes in the surface of the guide plate can instantaneously change the moving direction of the high-speed flue gas, the high-speed area on the front side of the flue is shifted towards the rear side of the flue, the speed field of the flue gas in the area between a catalyst bed layer and the guide plate is more uniformly distributed, and the local erosion of the high-speed flue gas on the front side of the flue to the catalyst bed layer is avoided, so that.
The flow field distribution analysis can be visually and accurately carried out on the internal structure of the SCR denitration system, the flow guide hole arrangement scheme can be quickly and accurately obtained without changing the actual internal structure of the denitration system, and the efficiency of the optimized design of the internal structure of the SCR denitration system is improved.
Drawings
FIG. 1 is a schematic diagram of the internal structure of an SCR denitration system according to the present invention;
fig. 2 is a schematic perspective view of an arc-shaped baffle of a fourth flow guide device in the embodiment;
FIG. 3 is a schematic cross-sectional view of an arc-shaped baffle of a fourth flow guiding device in the embodiment;
the notation in the figure is: 1. the device comprises a flue gas inlet end 21, a first flow guide device, a second flow guide device, a third flow guide device, a fourth flow guide device, a third ammonia spraying grid, a fourth ammonia spraying grid, a mixer, a third ammonia spraying grid, a rectifying grid, a fourth ammonia spraying grid, a catalyst bed layer, a fourth.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
As shown in fig. 1, an internal structure of an SCR denitration system includes a flue gas inlet end 1 and a flue gas outlet end 7, an ammonia injection grid 3, a mixer 4, a rectification grid 5 and a catalyst bed layer 6 are sequentially arranged between the flue gas inlet end 1 and the flue gas outlet end 7, the flue gas inlet end 1 is connected to the flue gas outlet end 7 through a first horizontal channel, a first vertical channel, a second horizontal channel and a second vertical channel, the first horizontal channel is connected to the first vertical channel through a first straight bend, the first vertical channel is connected to the second horizontal channel through a second straight bend, the second horizontal channel is connected to the second vertical channel through a third straight bend, and the second vertical channel is connected to the flue gas outlet end;
install first guiding device 21 in the first horizontal passage, first turn straight the position and install second guiding device 22, spout ammonia grid 3 and blender 4 and all install in first vertical passageway, blender 4 is located the top of spouting ammonia grid 3, third guiding device 23 is installed to second turn straight the position, fourth guiding device 24 is installed to third turn straight the position, rectification grid 5 and catalyst bed 6 are all installed in the second vertical passageway, rectification grid 5 is located between fourth guiding device 24 and the catalyst bed 6, wherein, first guiding device 21 includes the polylith parallel guide plate that is parallel to each other in the vertical direction, second guiding device 22, third guiding device 23 are constituteed by polylith arc guide plate, and the arc guide plate quantity of second guiding device 22 is less than the arc guide plate quantity of third guiding device 23.
As shown in fig. 2, the fourth flow guiding device 24 includes a plurality of arc-shaped flow guiding plates with the same size and distributed at equal intervals, wherein the arc-shaped flow guiding plate near the third straight-bending inner side is provided with flow guiding holes. In this embodiment, the diameter of the diversion holes is 60mm, the distance between the centers of the holes is 80mm, and 11 diversion holes are formed in one arc-shaped diversion plate.
In this embodiment, as shown in fig. 3, 9 arc-shaped deflectors made of high temperature resistant material with the same size are arranged at the third straight-bending position and above the rectification grids at the third straight-bending position. These 9 arc guide plate main parts are the 90 degrees circular arcs that the radius is 600mm, and the upper end of these 9 arc guide plates all is connected with 100mm long horizontal straight board, the lower extreme all is connected with 500mm long vertical fin to this evenly distributed effect that can further promote the flue gas.
The invention mainly realizes that the speed of the front side of the flue is uniformly distributed to the rear side of the flue to achieve the optimal uniform flow field through the holes by punching the arc-shaped guide plate at the third straight-bent position, so that the denitration system adapts to the characteristics of the change of working conditions in the flue, the denitration efficiency is improved, and the abrasion, blockage and ammonia escape effects of the catalyst are reduced.
In practical application, the invention mainly determines the optimal flow guide hole opening scheme by constructing a simulation model and combining a numerical simulation mode, and the specific process is as follows:
s1, constructing a simulation model corresponding to the internal structure of the SCR denitration system, wherein at the moment, no flow guide hole is formed in each of a plurality of arc-shaped plates of the fourth flow guide device, obtaining flow field distribution of flue gas in a region between a catalyst bed layer and the fourth flow guide device through numerical simulation, and determining an initial flue gas speed deviation value;
s2, for the fourth flow guide device, sequentially and equidistantly arranging flow guide holes on the first arc-shaped flow guide plate close to the inner side of the third straight bend, and sequentially obtaining the flow field distribution of the flue gas in the area between the catalyst bed layer and the fourth flow guide device through numerical simulation to obtain a plurality of corresponding flue gas speed deviation values, wherein if the plurality of flue gas speed deviation values have data smaller than or equal to a preset deviation value, the arrangement scheme of the flow guide holes corresponding to the flue gas speed deviation values is the optimization scheme of the internal structure, otherwise, the step S3 is continuously executed;
and S3, for the fourth flow guide device, sequentially forming flow guide holes at equal intervals on each arc-shaped flow guide plate from the second arc-shaped flow guide plate close to the inner side of the third straight bend, sequentially obtaining a plurality of corresponding flue gas speed deviation values through numerical simulation, and forming a flow guide hole forming scheme corresponding to the flue gas speed deviation value until the flue gas speed deviation value with the numerical value smaller than or equal to the preset deviation value is obtained, namely, the optimization scheme of the internal structure is obtained.
In this embodiment, the predetermined deviation value is specifically 15%.
The punching arc-shaped guide plate device obtained through optimization design can optimize and analyze NOx concentration and speed deviation under different working conditions, effectively improve gas speed distribution nonuniformity, and improve uniformity of a catalyst front flue gas flow field, so that abrasion inactivation of a catalyst bed layer is reduced, the service life of a catalyst is prolonged, and the efficiency of an SCR denitration device is ensured.
In summary, the invention provides an internal structure of a guide plate for improving flow field uniformity of an SCR denitration system and a design method thereof, and the internal structure of the guide plate combines a method of numerical simulation and a cold state simulation model, so as to perform numerical simulation on the existing denitration system, analyze the flow field distribution condition, perform punching optimization simulation on an arc-shaped guide plate above a catalyst bed layer, and determine an optimal punching scheme after continuously improving the flow field distribution. The catalyst bed layer is prevented from being locally and excessively eroded, and the service life of the catalyst is prolonged.
The arc-shaped guide plate above the rectifying grid in the denitration system is punched, the optimized gas flow direction can be realized, the speed of the front side of the flue can be more uniformly distributed to the rear side of the flue through the hole gaps, the optimal uniform flow field is achieved, the denitration system is adaptive to the characteristics of working condition change in the flue of the boiler, the abrasion inactivation of a catalyst layer is reduced, the effect of blockage and ammonia escape is achieved, the service life of a catalyst is effectively prolonged, the denitration efficiency is improved, the existing boiler flue does not need to be greatly changed, and the denitration system meets the requirements of environmental protection, economy, safety, energy conservation and the like.
Claims (10)
1. An internal structure of an SCR (selective catalytic reduction) denitration system is characterized by comprising a flue gas inlet end (1) and a flue gas outlet end (7), wherein an ammonia spraying grid (3), a mixer (4), a rectification grid (5) and a catalyst bed layer (6) are sequentially arranged between the flue gas inlet end (1) and the flue gas outlet end (7), the flue gas inlet end (1) is connected to the flue gas outlet end (7) through a first horizontal channel, a first vertical channel, a second horizontal channel and a second vertical channel, the first horizontal channel is connected with the first vertical channel through a first straight bend, the first vertical channel is connected to the second horizontal channel through a second straight bend, the second horizontal channel is connected to the second vertical channel through a third straight bend, and the second vertical channel is connected with the flue gas outlet end (7);
install first guiding device (21) in the first horizontal passage, second guiding device (22) are installed to first bending position, it all installs in first vertical passageway to spout ammonia grid (3) and blender (4), blender (4) are located the top of spouting ammonia grid (3), third guiding device (23) are installed to second bending position, fourth guiding device (24) are installed to third bending position, rectification grid (5) and catalyst bed (6) are all installed in the vertical passageway of second, rectification grid (5) are located between fourth guiding device (24) and catalyst bed (6), fourth guiding device (24) are including the polylith arc guide plate that the size is the same and equidistant distribution, the water conservancy diversion hole has been seted up on the arc guide plate.
2. The internal structure of an SCR denitration system according to claim 1, wherein the arc radius of the arc-shaped guide plate is 600mm, and the arc angle is 90 °.
3. The internal structure of an SCR denitration system of claim 2, wherein the upper end of the arc-shaped guide plate is connected with a horizontal straight plate, and the lower end of the arc-shaped guide plate is connected with a vertical tail wing.
4. The internal structure of an SCR denitration system according to claim 3, wherein the length of the horizontal straight plate is 100mm, and the length of the vertical rear wing is 500 mm.
5. The internal structure of an SCR denitration system of claim 1, wherein the arc-shaped guide plate is provided with a plurality of equally spaced guide holes.
6. The internal structure of an SCR denitration system according to claim 5, wherein the diameter of the flow guide hole is 60 mm.
7. The internal structure of an SCR denitration system according to claim 1, wherein the arc-shaped deflector is made of a high-temperature resistant material.
8. An internal structure of an SCR denitration system according to claim 1, wherein the first flow guide means (21) comprises a plurality of parallel flow guide plates which are parallel to each other in a vertical direction.
9. A design method for an internal structure of an SCR denitration system according to claim 1, comprising the steps of:
s1, constructing a simulation model corresponding to the internal structure of the SCR denitration system, wherein at the moment, no flow guide hole is formed in each of a plurality of arc-shaped plates of the fourth flow guide device, obtaining flow field distribution of flue gas in a region between a catalyst bed layer and the fourth flow guide device through numerical simulation, and determining an initial flue gas speed deviation value;
s2, for the fourth flow guide device, sequentially and equidistantly arranging flow guide holes on the first arc-shaped flow guide plate close to the inner side of the third straight bend, and sequentially obtaining the flow field distribution of the flue gas in the area between the catalyst bed layer and the fourth flow guide device through numerical simulation to obtain a plurality of corresponding flue gas speed deviation values, wherein if the plurality of flue gas speed deviation values have data smaller than or equal to a preset deviation value, the arrangement scheme of the flow guide holes corresponding to the flue gas speed deviation values is the optimization scheme of the internal structure, otherwise, the step S3 is continuously executed;
and S3, for the fourth flow guide device, sequentially forming flow guide holes at equal intervals on each arc-shaped flow guide plate from the second arc-shaped flow guide plate close to the inner side of the third straight bend, sequentially obtaining a plurality of corresponding flue gas speed deviation values through numerical simulation, and forming a flow guide hole forming scheme corresponding to the flue gas speed deviation value until the flue gas speed deviation value with the numerical value smaller than or equal to the preset deviation value is obtained, namely, the optimization scheme of the internal structure is obtained.
10. A design method according to claim 9, wherein the predetermined deviation value is 15%.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113477073A (en) * | 2021-05-31 | 2021-10-08 | 四川思达能环保科技有限公司 | Catalyst air inlet structure for dedusting and denitration device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113477073A (en) * | 2021-05-31 | 2021-10-08 | 四川思达能环保科技有限公司 | Catalyst air inlet structure for dedusting and denitration device |
| CN113477073B (en) * | 2021-05-31 | 2023-10-03 | 四川思达能环保科技有限公司 | Catalyst air inlet structure for dedusting and denitration device |
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