CN104524972A - Design method of ammonia nozzle of SCR denitration device - Google Patents
Design method of ammonia nozzle of SCR denitration device Download PDFInfo
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- CN104524972A CN104524972A CN201410822742.2A CN201410822742A CN104524972A CN 104524972 A CN104524972 A CN 104524972A CN 201410822742 A CN201410822742 A CN 201410822742A CN 104524972 A CN104524972 A CN 104524972A
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- ammonia
- spray ammonia
- mouth
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- denitration device
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Abstract
The invention provides a design method of an ammonia nozzle of an SCR denitration device. Aiming at the condition of ultrashort mixing distance between smoke and ammonia in the denitration device, the method comprises the following steps: optimizing the flare angle theta of the ammonia nozzle and distributing the ammonia nozzle in a staggering manner to avoid the condition that the ammonia concentration is locally too high or too low; determining the structural parameters of the ammonia nozzle according to the mixing distance, the distance between ammonia spraying grating pipes, the distance between holes and the length of the ammonia nozzle, wherein the structural parameters of the ammonia nozzle comprise the flare angle theta of the ammonia nozzle and the cross displacement delta of the ammonia nozzle. According to the method, under the condition that the mixing distance is ultrashort, the mixing uniformity of the smoke and the ammonia reaching the plane of a catalyst inlet is improved, the NOx removing efficiency is ensured, and the ammonia escape amount is reduced.
Description
Technical field
The present invention relates to a kind of method for designing mixed apart from the SCR denitration device spray ammonia mouth in ultrashort situation, belong to thermoelectricity environmental technology field.
Background technology
SCR (SCR-Selective Catalytic Reduction) technology is the flue gases purification be most widely used in current Coal-fired Thermal Power station.Its cardinal principle utilizes ammonia (NH
3) and nitrogen oxide (NO
x) at V
2o
5/ WO
3/ TiO
2or V
2o
5/ MoO
3/ TiO
2the redox reaction of carrying out under the effect of the catalyst of composition, generates nitrogen (N
2) and water (H
2thus to remove in flue gas harmful NO O),
x.When carrying out denitrification apparatus design, in order to ensure the NO of SCR system
xremoval efficiency also controls amount of ammonia slip, needs to take certain measure to make ammonia and flue gas Homogeneous phase mixing.Common way installs mixing grid additional in ammonia-spraying grid downstream, and provide sufficiently long mixing flue for ammonia and flue gas, make the ammonia density distribution arriving catalyst plane even as much as possible, generally distribute relative standard deviation for standard with ground floor catalyst inlet plane ammonia density, require that this index is less than 5%.
But the China that is applied in of SCR denitration technology starts late, most of Coal-fired Thermal Power stands in first stage of construction and does not consider denitrating flue gas, and installing additional of its SCR system needs based on original boiler structure, belongs to improvement and design.Carry out analysis to different transformation projects to find, due to the existence of existing boiler structure and beam frame structure, the design of SCR system receives more constraint.Common is as shorter in the distance between ammonia-spraying grid installation site with catalyst inlet plane, and the flue gas and the ammonia that arrive catalyst inlet can not fully mix.For this type of situation, sometimes can install flow-guiding structure targetedly additional and improve the mixture homogeneity of flue gas and ammonia after flow straightening grid, but in small part situation, this is apart from ultrashort, even do not install the space of mixing grid additional, the ammonia density distribution of catalyst plane does not often reach requirement, affects the denitration efficiency of SCR system.By carrying out the mixability that reasonably optimizing design can improve flue gas and ammonia, the Effec-tive Function of assurance device to spray ammonia mouth structure parameter.
Find after to existing technical literature retrieval, Li Na, Lu Zuoji, Qin Cuijuan have delivered " the ammonia-spraying grid method for designing research based on parameterized model is optimized " in " power technology and environmental protection " (the 28th volume the 2nd phase in 2012).Analyze ammonia-spraying grid geometric parameter (spray ammonia tube pitch, the spray ammonia pitch of holes) impact on spray ammonia characteristic, propose a kind of method for designing, with obtain ammonia density distribution relative standard deviation minimum time ammonia-spraying grid structure.But this article does not carry out concrete analysis research to spray ammonia mouth, also from the angle of spray ammonia mouth, design is not optimized to ammonia-spraying grid.
Summary of the invention
For defect of the prior art, the object of this invention is to provide the method for designing of a kind of SCR denitration device spray ammonia mouth, the method is optimized spray ammonia mouth structure apart from ultrashort at denitrification apparatus mixing flue, improve and arrive the flue gas of catalyst inlet plane and the mixture homogeneity of ammonia, ensure NO
xremoval efficiency, reduces amount of ammonia slip.
For realizing above object, the invention provides the method for designing of a kind of SCR denitration device spray ammonia mouth, the method is optimized spray ammonia mouth structure according to mixing distance, ammonia-spraying grid tube pitch, pitch of holes, and spray ammonia mouth is designed to be interspersed, in mixing apart from ultrashort, ensure that flue gas and the ammonia of arrival catalyst inlet plane have high mixture homogeneity, avoid the Local enrichment that ammonia causes owing to having little time to spread.
Preferably, the structural parameters of described spray ammonia mouth, comprising: the subtended angle θ of spray ammonia mouth, the staggered displacement Δ of spray ammonia mouth, these parameters are according to mixing distance H, tube pitch D
1, pitch of holes D
2, spray ammonia mouth length L emulates optimizing by CFD and obtains.Wherein, mixing distance H refers to the distance between ammonia-spraying grid installation site and catalyst inlet plane; Tube pitch D
1refer to the distance between adjacent spray ammonia tube hub axle on ammonia-spraying grid; Pitch of holes D
2refer to the distance between the adjacent spray ammonia mouth central shaft of the same side on same spray ammonia pipe.
Preferably, the subtended angle θ of described spray ammonia mouth, refers to: the spray ammonia mouth of V-shaped distribution on same spray ammonia pipe take pad as drift angle, toward the angle between the nozzle of both direction installation on same pad.
Preferably, described spray ammonia mouth is interspersed, and refers to: the spray ammonia mouth of adjacent spray ammonia pipe does not also line up, and there is a displacement Δ, displacement Δ and pitch of holes D between the spray ammonia mouth of arbitrary neighborhood spray ammonia pipe along spray ammonia pipe direction
2relevant, be pitch of holes D
2half.
Preferably, described ultrashort mixing distance, refers to: ammonia-spraying grid installation site is not enough to the distance of catalyst inlet plane the device installing mixing grid or other raising flue gases and ammonia mixture homogeneity.
Preferably, spray ammonia speed and the main flow average speed of described spray ammonia mouth are close, if ammonia-spraying grid upstream velocity of flue gas is uniformly distributed, adopts and evenly spray ammonia, if not be uniformly distributed, then adopt non-homogeneous spray ammonia.
Compared with prior art, the present invention has following beneficial effect:
The present invention in mixing apart from ultrashort, can improve the mixture homogeneity of flue gas and ammonia, improves the distribution of catalyst inlet plane ammonia, thus avoid too much, very few the escaping of ammonia, the NO caused of regional area ammonia
xremove not exclusively, there is the effect improving SCR denitration system denitration efficiency, meanwhile, under phase same level, the consumption of catalyst can be reduced to a certain extent, cost-saving.
Accompanying drawing explanation
By reading the detailed description done non-limiting example with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:
Fig. 1 is SCR denitration device structure of the present invention and ammonia-spraying grid schematic diagram;
In figure: 1 is ammonia-spraying grid, and 2 is SCR reactor;
Fig. 2 is ammonia-spraying grid scale diagrams of the present invention;
Fig. 3 is that ammonia mouth scale diagrams is sprayed in the present invention
Fig. 4 is optimum results figure;
When Fig. 5 is conventional spray ammonia mouth design, Catalytic Layer plane of inlet central area ammonia density cloud charts;
Fig. 6 is after spray ammonia mouth optimal design, Catalytic Layer plane of inlet central area ammonia density cloud charts.
Detailed description of the invention
Below in conjunction with specific embodiment, the present invention is described in detail.Following examples will contribute to those skilled in the art and understand the present invention further, but not limit the present invention in any form.It should be pointed out that to those skilled in the art, without departing from the inventive concept of the premise, some distortion and improvement can also be made.These all belong to protection scope of the present invention.
The present embodiment provides the method for designing of the SCR denitration device spray ammonia mouth in a kind of very-short-reach situation, by carrying out adjusting and optimizing to the structural parameters of spray ammonia mouth, change the angle of emergence of ammonia, then change the distribution of the ammonia arriving catalyst, improve the mixture homogeneity of flue gas and ammonia; According to ammonia-spraying grid to distance, tube pitch, the pitch of holes of catalyst, determine the structural parameters spraying ammonia mouth further, structural parameters refer to the subtended angle θ of spray ammonia mouth, the staggered displacement Δ of spray ammonia mouth, and these parameters are according to mixing distance H, tube pitch D
1, pitch of holes D
2, spray ammonia mouth length L emulates optimizing by CFD and obtains.
As shown in Figure 1, be certain tower type gas unit SCR denitration device structure and ammonia-spraying grid schematic diagram, 1 is ammonia-spraying grid, and 2 is SCR reactor; Wherein ammonia-spraying grid upstream is Multi-layer exchanging heat device structure, and ammonia-spraying grid is ultrashort to the distance of catalyst, cannot install mixing grid, therefore adopts the spray ammonia mouth structure designed by the present invention; Wherein:
Ammonia-spraying grid is H to the distance of catalyst.
Ammonia-spraying grid tube pitch, pitch of holes are respectively D
1, D
2, spray ammonia mouth length is L, and the subtended angle of spray ammonia mouth is θ, and the displacement that is interspersed of spray ammonia mouth is Δ, and size marking as shown in Figure 2 and Figure 3.
Above-mentioned parameter θ, Δ are emulated optimizing obtained by CFD (computational fluid dynamics), optimum results figure as shown in Figure 4, wherein:
H＝3500mm；
D
1＝500mm，D
2＝300mm；
L＝200mm；
Δ＝150mm；
θ＝80°。
In the present embodiment, because this entrance is positioned at Multi-layer exchanging heat device downstream, therefore inlet flue gas is considered as being uniformly distributed, flue entrance velocity of flue gas 5.7m/s, and spray ammonia speed 6m/s, exhanst gas outlet static pressure-1000Pa, temperature is set as 620K.CFD emulation uses Fluent 6.3.26 software, and rounding catalyst inlet planar dimension during emulation, is 7000mm × 5000mm.
In Fig. 1, SCR reactor is containing one deck, and adopt honeycombed catalyst, the plane of inlet that flue gas enters SCR reactor is rectangle.
When analyzing, getting catalyst inlet planar central region as object, avoiding the impact of space structure constraint on simulation result.
When Fig. 5 is not for carrying out the design of spray ammonia mouth, denitrification apparatus Catalytic Layer plane of inlet central area ammonia density distribution map, overlooks, and left side is nearly boiler side, and paper is pointed to by reader in flow of flue gas direction.
When not carrying out the design of spray ammonia mouth, catalyst inlet plane ammonia density distribution relative standard deviation is 11.51%.As can be seen from cloud atlas, the distribution of ammonia is strip, high concentration and low concentration region spaced apart, degree of irregularity is higher.Now, at area with high mercury, ammonia can not catalyzedly react completely consumption, causes the escaping of ammonia, after leaving reactor, can cause corrosion to upstream device; At low concentration region, denitration reaction can not carry out completely, goes out in the gas of reactor and still comprises a large amount of NO
x, denitration efficiency can not be guaranteed.After design is optimized to spray ammonia mouth, corresponding ammonia density distribution relative standard deviation is declined to a great extent, be reduced to 2.18%, corresponding ammonia density cloud charts as shown in Figure 6, can find out, significantly strip distribution disappears before, and except a few regions concentration is higher, the ammonia density distribution in most of region is all tending towards even.Meanwhile, after optimal design, the maximum concentration of catalyst inlet plane ammonia declines comparatively before to some extent.Statistics shows, under not carrying out spray ammonia mouth design conditions, the maximum concentration arriving the ammonia of catalyst inlet plane exceedes mean concentration about 15%, and after optimal design, the maximum concentration of corresponding ammonia exceedes mean concentration less than 5%.
Visible, the ammonia density distribution consistency degree of Catalytic Layer porch can be made at spray ammonia to get a promotion apart from using the technology of the present invention ultrashort, eliminate the non-uniform phenomenon of ammonia in Catalytic Layer porch, thus too much, very few the escaping of ammonia, the NO caused of the regional area ammonia avoiding ammonia density skewness to cause
xremove not exclusively, play the effect improving SCR denitration system denitration efficiency.
Above specific embodiments of the invention are described.It is to be appreciated that the present invention is not limited to above-mentioned particular implementation, those skilled in the art can make various distortion or amendment within the scope of the claims, and this does not affect flesh and blood of the present invention.
Claims (6)
1. the method for designing of a SCR denitration device spray ammonia mouth, it is characterized in that, the method is optimized spray ammonia mouth structure according to mixing distance, ammonia-spraying grid tube pitch, pitch of holes, and spray ammonia mouth is designed to be interspersed, avoid the Local enrichment caused because mixing has little time to spread apart from ultrashort, ammonia.
2. the method for designing of a kind of SCR denitration device spray ammonia mouth according to claim 1, is characterized in that, the structural parameters of described spray ammonia mouth refer to the staggered displacement Δ of the subtended angle θ of spray ammonia mouth, spray ammonia mouth, and these parameters are according to mixing distance H, tube pitch D
1, pitch of holes D
2, spray ammonia mouth length L emulates optimizing by CFD and obtains.
3. the method for designing of a kind of SCR denitration device spray ammonia mouth according to claim 2, it is characterized in that, the subtended angle θ of described spray ammonia mouth, refer to: the spray ammonia mouth of V-shaped distribution on same spray ammonia pipe, take pad as drift angle, toward the angle between the nozzle of both direction installation on same pad.
4. the method for designing of a kind of SCR denitration device spray ammonia mouth according to claim 2, it is characterized in that, described spray ammonia mouth is interspersed, refer to: the spray ammonia mouth of adjacent spray ammonia pipe does not also line up, a displacement Δ is there is, displacement Δ and pitch of holes D along spray ammonia pipe direction between the spray ammonia mouth of arbitrary neighborhood spray ammonia pipe
2relevant, displacement Δ is the half of pitch of holes.
5. a kind of SCR denitration device reducing flue deflector method for designing according to any one of claim 1-4, it is characterized in that, described ultrashort mixing distance refers to that ammonia-spraying grid installation site is not enough to install the device improving flue gas and ammonia mixture homogeneity to the distance of catalyst inlet plane.
6. a kind of SCR denitration device reducing flue deflector method for designing according to any one of claim 1-4, it is characterized in that, spray ammonia speed and the main flow average speed of described spray ammonia mouth are close, if ammonia-spraying grid upstream velocity of flue gas is uniformly distributed, adopt and evenly spray ammonia, if not be uniformly distributed, then adopt non-homogeneous spray ammonia.
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Cited By (5)
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| CN104906947A (en) * | 2015-05-18 | 2015-09-16 | 吴友琴 | Ammonia gas distribution system |
| CN105311959A (en) * | 2015-12-09 | 2016-02-10 | 光大环保（中国）有限公司 | Ammonia spraying grid for low-temperature SCR denitrification system |
| CN106540543A (en) * | 2017-01-17 | 2017-03-29 | 启迪桑德环境资源股份有限公司 | A kind of multiple pass type selective catalytic reduction denitration device |
| CN109636048A (en) * | 2018-12-18 | 2019-04-16 | 上海交通大学 | A kind of non-homogeneous spray ammonia convex quadratic programming optimum design method of SCR denitration system |
| CN113617206A (en) * | 2020-05-07 | 2021-11-09 | 江苏海默环保科技有限公司 | Control method of spray gun, control system of spray gun and incineration system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113617206A (en) * | 2020-05-07 | 2021-11-09 | 江苏海默环保科技有限公司 | Control method of spray gun, control system of spray gun and incineration system |
| CN113617206B (en) * | 2020-05-07 | 2023-08-22 | 江苏海默环保科技有限公司 | Control method of spray gun, control system of spray gun and incineration system |
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