CN106540542A - A kind of efficient SCR reactors of low dirt - Google Patents

A kind of efficient SCR reactors of low dirt Download PDF

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Publication number
CN106540542A
CN106540542A CN201611137875.1A CN201611137875A CN106540542A CN 106540542 A CN106540542 A CN 106540542A CN 201611137875 A CN201611137875 A CN 201611137875A CN 106540542 A CN106540542 A CN 106540542A
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China
Prior art keywords
section
porous plate
reactor
distance
porous
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CN201611137875.1A
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杨鸣
杨一鸣
李洁
李坚
何洪
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Beijing University of Technology
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Beijing University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • 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
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8631—Processes characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • 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
    • B01D53/90—Injecting reactants

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  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Chimneys And Flues (AREA)

Abstract

A kind of efficient SCR reactors of low dirt, it is adaptable to the relatively low (≤50mg/Nm of dust content in flue gas3) SCR reactors.It is characterized in that：(1) this reactor is symmetrical structure, and cross section is square；(2) this reactor inlet section is flaring flue, and, from the horizontal by an included angle A, the scope of A should be below 45 ° for entrance hypotenuse；(3) first and second porous plates are located in flaring flue, and the distance in first block of porous plate and the first section is H1；First section is gas approach and reactor inlet section interface；The distance in i.e. second block porous plate and the second section is H2, and the second section is the interface of reactor inlet section and reactor body section；In the range from：0≤H1≤(1/2)H3；0≤H2≤(1/3)H3；H3 is the distance between the first section and second section；Present configuration is simple, easy to process, and Flow Field Distribution is good.

Description

A kind of efficient SCR reactors of low dirt
Technical field
The present invention relates to a kind of relatively low efficient SCR reactors of dust content suitable for flue gas, more particularly, to one kind The internal structure of reactor.
Background technology
SCR is a kind of efficient gas denitrifying technology, is widely used in boiler, stove and other a large amount of nitrogen oxides of generation Industrial plants denitration administer.The denitration efficiency of SCR technology is affected by factors, and wherein Flow Field Distribution is most important skill One of art index.The examination face of Flow Field Distribution uniformity is on the cross section at ground floor catalyst surface upstream 0.5m, (Fig. 2 cuts Face 3 and the distance of ground floor catalyst surface, H4=0.5m), it is desirable to the maximum deviation of the velocity of flue gas distribution on the cross section The definition of coefficient (CV)≤15%, CV is：
Wherein：
Meansigma methodss
Vi：Sampled value
N：Sampling number
Conventional SCR reactors generally adopt vertically arranged form, that is, flue gas from vertical flue vertically upward, and Reactor head region, then vertical flow down are entered by horizontal flue afterwards, commutator and catalyst is sequentially passed through, finally from Reactor outlet is discharged.That is the flue gas of high speed needs the steering through at least 180 degree, gets to ground floor catalysis Agent.Conventional reactor schematic diagram is shown in Fig. 1, and in the case where deflector is not provided with, the Flow Field Distribution of its top area is very uneven Even, as shown in Figure 5 and Figure 6, when commutator is installed additional, its CV value is generally more than 30%；When not installing commutator additional, its CV value is led to Often more than 40%, so as to have impact on denitration efficiency.Therefore, generally conventional reactor head (commutator is with upper bit) needs Install substantial amounts of deflector additional to improve flow field, be allowed to meet technical requirement.
The design of deflector and optimization process are complicated, if design is improper, the flow field index of reactor can not meet requirement. The design of deflector and Optimization Work generally need the long period, and usually becoming affects one of key factor of project progress.Separately Outward, accurately whether the machining accuracy of deflector, install, can all affect final Flow Field Distribution.China needs to carry out denitration at present The industry of improvement is numerous, and denitration engineering quantity is huge, therefore, research and develop a kind of simple structure, it is easy to process, Flow Field Distribution performance is good SCR reactors seem particularly urgent.
The content of the invention
The purpose of the present invention is exactly to solve the above problems for part, there is provided a kind of relatively low suitable for dust content flue gas (≤50mg/Nm3) situation, simple structure, easy to process, the good SCR reactors of Flow Field Distribution, schematic diagram be shown in Fig. 2.Utilize Advanced CFD software star-ccm+, and combine physics model measurement, the present invention to the internal structure to traditional reactor again Designed.
A kind of efficient SCR reactors of low dirt, it is characterised in that：
(1) this reactor is symmetrical structure, and cross section is square；
(2) this reactor inlet section is flaring flue, and from the horizontal by an included angle A, the scope of A should be for entrance hypotenuse Less than 45 °；
(3) first and second porous plates are located in flaring flue, and the distance in first block of porous plate and the first section is H1；The One section is gas approach and reactor inlet section interface；
The distance in i.e. second block porous plate and the second section is H2, and the second section is reactor inlet section and reactor body The interface of section；In the range from：0≤H1≤(1/2)H3；0≤H2≤(1/3)H3；
H3 is the distance between the first section and second section；
The percent opening of (4) first porous plates is 45%～60%, and the percent opening of the second porous plate is 35%～55%；Hole Arrangement should meet equally distributed requirement.
Further, the hole of the first and second porous plates meets following characteristics：Outermost small hole center and porous plate edge Minimum distance be H5, the distance of the adjacent small hole center of any two is H6, should meet H5=(1/2) H6.
CFD software numerical simulation is mainly used with drag：
(1) gas phase turbulance model
A) equation of continuity：
B) equation of momentum of X-direction：
C) equation of momentum in Y-direction：
D) equation of momentum in Z-direction：
E) K equations：
F) ε equations：
Wherein, coefficient of eddy viscosityP is Fluid pressure；ρ is gas density；Turbulent flow produces item GkFor：
The above differential equation, can be write as following common version：
Wherein, φ is dependent variable, ΓφFor the diffusion coefficient of dependent variable φ, SφCorresponding in dependent variable conservation equation Source item.
Being expressed as unified transport equation form is：
In formula, items are from left to right followed successively by convective term, diffusion term and source item.
(2) porous media model
For the catalyst layer pressure drop in SCR reactors, by regarding catalyst layer as porous media simulation, porous Plate is also included.Its droop loss simulation formula is as follows：
Momentum source term, Pa/m on Si-i directions in formula；μ-mobilization dynamic viscosity, Pas；α-medium permeability；vi— I is to velocity component, m/s；ρ-density, kg/m3；C2- internal drag the factor, 1/m.
The setting of physical model is defined using the nondimensionalization of characteristic of fluid amount, wherein having Reynolds number, Euler's numbers, Bath Number, Fourier number and model geometric ratio value.
The achievable following functions of the present invention：
Consider the uncertainty and complexity (see Fig. 4) of flue trend, for reactor flow field influence degree, The present invention is shown in Fig. 9 without the need for flow field technical requirement (CV values are less than 15%) is met by inside reactor sets up deflector And Figure 10.
Description of the drawings
Fig. 1 is the structural representation of traditional SCR reactors.
Fig. 2 is the structural representation of the SCR reactors of the present invention
Fig. 3 is the structural representation of the SCR reactors and porous plate of the present invention
Fig. 4 is the schematic diagram of gas approach trend
Fig. 5 is traditional SCR inside reactors entirety velocity profile
Fig. 6 is traditional SCR reactor catalysts upstream flow rate scattergram
Fig. 7 is SCR inside reactors entirety velocity profile (being not provided with porous plate) of the present invention
Fig. 8 is SCR reactor catalysts upstream flow rate scattergram (being not provided with porous plate) of the present invention
Fig. 9 is SCR inside reactors entirety velocity profile (setting porous plate) of the present invention
Figure 10 is SCR reactor catalyst upstream flow rate scattergrams (setting porous plate) of the present invention
Specific embodiment
After redesign, including：(1) reactor symmetrical structure of the invention (i.e. cross section is square)；(2) present invention Reactor inlet section hypotenuse from the horizontal by an included angle A, the scope of A should be below 45 °；(3) porous plate of the present invention is located at Block porous plate of the ad-hoc location of flaring flue, i.e., first and the first section (gas approach and reactor inlet section interface) away from From for H1；The distance in i.e. second block porous plate and the second section interface of reactor body section (reactor inlet section with) is H2, in the range from：0≤H1≤(1/2)H3；0≤H2≤(1/3)H3.(4) percent opening of porous plate is within the specific limits.Wherein The percent opening of the first porous plate is 45%～60%, and the percent opening of the second porous plate is 35%～55%.The definition of percent opening is： m2*A/H72, areas of the A for single hole, the length of sides of the H7 for porous plate.Hole can be circular or square, and when hole is circular, which half Footpath is R, and the definition of percent opening is：m2*πR2/H72；When hole for it is square when, its length of side is H8, and the definition of percent opening is：m2*H82/ H72.Line number or columns of the wherein m for circular hole.(5) arrangement in hole should meet the requirement for being uniformly distributed part, in outermost aperture The heart is H5 with the minimum distance at porous plate edge, and the distance of the adjacent small hole center of any two is H6, should meet H5=(1/2) H6。
(1) reactor inlet section is required
, from the horizontal by an included angle A, the scope of A should be at no more than 45 ° for the reactor inlet section hypotenuse of the present invention.
(2) reactor body section parameter request
Reactor body section cross-sectional gas flow velocity typically should be controlled in below 6m/s.
Process tolerance not limit.
(3) porous plate location parameter
The porous plate of the present invention is located at the ad-hoc location of flaring flue, wherein：
0≤H1≤(1/2)H3
0≤H2≤(1/3)H3
(4) percent opening of porous plate is required
The percent opening of porous plate is within the specific limits.Wherein the percent opening of the first porous plate is 45%～60%, more than second The percent opening of orifice plate is 35%～55%.
(5) Spreading requirements in hole
The arrangement in hole should meet Even distribution entails, and outermost small hole center with the minimum distance at porous plate edge is H5, the distance of the adjacent small hole center of any two is H6, should meet H5=(1/2) H6.
CV values can be met by the percent opening of the position and the first porous plate and the second porous plate that adjust porous plate will Ask.
Exhaust gas volumn is 60,000 Nm3/ h, cross-sectional gas flow velocity is 2.5m/s, the first porous plate at (1/4) H3, perforate Rate is 58%；At (1/4) H3, percent opening is 51% to first porous plate；CV is 13.1%.
Exhaust gas volumn is 600,000 Nm3/ h, cross-sectional gas flow velocity is 2.0m/s, the first porous plate at (1/3) H3, perforate Rate is 52%；At (1/4) H3, percent opening is 48% to first porous plate；CV is 12.6%.

Claims (2)

1. efficient SCR reactors of a kind of low dirt, it is characterised in that：
(1) this reactor is symmetrical structure, and cross section is square；
(2) this reactor inlet section is flaring flue, and, from the horizontal by an included angle A, the scope of A should be at 45 ° for entrance hypotenuse Below；
(3) first and second porous plates are located in flaring flue, and the distance in first block of porous plate and the first section is H1；First section Face is gas approach and reactor inlet section interface；
The distance in i.e. second block porous plate and the second section is H2, and the second section is reactor inlet section and reactor body section Interface；In the range from：0≤H1≤(1/2)H3；0≤H2≤(1/3)H3；
H3 is the distance between the first section and second section；
The percent opening of (4) first porous plates is 45%～60%, and the percent opening of the second porous plate is 35%～55%；The arrangement in hole Equally distributed requirement should be met.
2. a kind of efficient SCR reactors of low dirt as claimed in claim 1, it is characterised in that the hole of the first and second porous plates Meet following characteristics：Outermost small hole center is H5 with the minimum distance at porous plate edge, in the adjacent aperture of any two The distance of the heart is H6, should meet H5=(1/2) H6.
CN201611137875.1A 2016-12-12 2016-12-12 A kind of efficient SCR reactors of low dirt Pending CN106540542A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014084543A1 (en) * 2012-11-27 2014-06-05 주식회사 파나시아 Denitrification system comprising perforated plate for preventing drift of flow
CN103933859A (en) * 2014-03-31 2014-07-23 上海德凯工业技术有限公司 SCR (Selective Catalytic Reduction) denitration system for tail gas treatment of acrylonitrile device
CN105597655A (en) * 2016-03-16 2016-05-25 北京化工大学 Gas distribution device
CN205627632U (en) * 2016-05-12 2016-10-12 西安西热锅炉环保工程有限公司 High performance SCR minimum discharge control system based on subregion mixes to be adjusted
CN206837859U (en) * 2016-12-12 2018-01-05 北京工业大学 A kind of efficient SCR reactors of low dirt

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014084543A1 (en) * 2012-11-27 2014-06-05 주식회사 파나시아 Denitrification system comprising perforated plate for preventing drift of flow
CN103933859A (en) * 2014-03-31 2014-07-23 上海德凯工业技术有限公司 SCR (Selective Catalytic Reduction) denitration system for tail gas treatment of acrylonitrile device
CN105597655A (en) * 2016-03-16 2016-05-25 北京化工大学 Gas distribution device
CN205627632U (en) * 2016-05-12 2016-10-12 西安西热锅炉环保工程有限公司 High performance SCR minimum discharge control system based on subregion mixes to be adjusted
CN206837859U (en) * 2016-12-12 2018-01-05 北京工业大学 A kind of efficient SCR reactors of low dirt

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