CN105457465B - A kind of SNCR SCR combine the design method of flue gas denitrification system technique - Google Patents
A kind of SNCR SCR combine the design method of flue gas denitrification system technique Download PDFInfo
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- CN105457465B CN105457465B CN201510828904.8A CN201510828904A CN105457465B CN 105457465 B CN105457465 B CN 105457465B CN 201510828904 A CN201510828904 A CN 201510828904A CN 105457465 B CN105457465 B CN 105457465B
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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
- B01D53/75—Multi-step processes
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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
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
Abstract
The present invention discloses the design method that a kind of SNCR SCR combine flue gas denitrification system technique, the mathematical modeling that the calculating of reducing agent volume flow rate and catalyst volume for initially setting up SNCR SCR combined denitration techniques are calculated；Then the temperature information of NOx concentration information in flue gas, the flow of flue gas and flue gas is obtained by measuring instrument measurement；Finally reducing agent volume flow rate and catalyst volume are calculated with reference to the information and mathematical modeling that measurement is obtained.Pass through the SNCR SCR combined denitration technological mathematical models of the present invention, to solve the volume flow rate of the reducing agent containing ammonia and the volume of design catalyst, it is possible to increase the denitration efficiency of medium small boiler, reduce the size of SCR catalyst, the probability of catalyst poisoning is reduced, input cost is reduced.
Description
Technical field
The present invention relates to chemical field, the design side of flue gas denitrification system technique is combined more particularly, to a kind of SNCR-SCR
Method.
Background technology
Contain substantial amounts of nitrogen oxygen in the flue gas discharged in coal-burning power plant, dangerous waste incineration processing, mineral matter smelting process
Compound (NOx), nitrogen oxides can be chemically reacted with ammonia under certain condition, generate environmentally safe nitrogen and
Water.SNCR and SCR technology are all to make reducing agent using ammonia or urea etc., its aqueous solution are sprayed into flue gas using nozzle, with cigarette
Chemoselective reduction occurs for the nitrogen oxides in gas, and product is nitrogen and water free from environmental pollution.The reaction temperature of two kinds of technologies
Degree is different, according to the research of the scholars such as Muzio, Miller, and SNCR reacts window at 1000 DEG C or so without using catalyst, but
Reaction window temperature is reduced to 240 DEG C~380 DEG C, and improve reaction efficiency by SCR because there is the participation of catalyst.
Using single SNCR techniques, its installation cost is relatively low, and the problem of being characterized in having the escaping of ammonia, denitration efficiency is got over
The problem of high the escaping of ammonia, is more notable, and by the escaping of ammonia control in below 10ppm, denitration efficiency is often no more than 40%, it is adaptable to
The not high regional denitrating flue gas processing of medium small boiler or emission request.And SCR techniques denitration efficiency reach 90% it is same
When can also have the disadvantage that installation cost is high, structure is complex, and many factors may by the control of the escaping of ammonia rate in below 3ppm
Cause catalyst poisoning, the progress of influence denitration work, it is common to use in large-sized boiler denitration process.
SNCR-SCR combined denitrations technique is simultaneously indirect by SNCR and SCR process combinations, although being also the shape by series connection
Formula is formed by connecting, but its working mechanism and directly series connection are distinguishing.It is by SNCR Technical investment costs are few, SCR skills
A kind of Novel flue gas denitrating technique that the advantage of art efficiency high is concentrated in together and then developed.Improve the reduction of SNCR parts
Agent flow rate, improves the denitration efficiency of SNCR techniques.Flue gas nitrogen oxide concentration after SNCR technique preliminary treatments is significantly reduced,
The pressure of SCR reactors is reduced, can suitably reduce the size of catalyst, reduction catalyst blockage, the probability of poisoning, reduction
Because of the cost of catalyst change.The ammonia of escape chemically reacts in the catalyst surface of SCR reactors with nitrogen oxides, by nitrogen
The concentration of oxide is reduced to limit row's standard, while reaching the purpose of control the escaping of ammonia.
The content of the invention
Present invention aims at a kind of design method of SNCR-SCR joints flue gas denitrification system technique is provided, to improve
The denitration efficiency of medium small boiler, while reducing the size of SCR catalyst, reduces the probability of catalyst poisoning, reduction is put into
This.
To reach above-mentioned purpose, the present invention is adopted the following technical scheme that：
Equipment for denitrifying flue gas involved by this programme includes SNCR reaction zones and SCR reaction zones, and SNCR reaction zones are arranged on
In boiler furnace, reaction temperature is provided with spray gun group between 875-1150 DEG C, the position of the atomizer of spray gun and burner hearth
Water-cooling wall is contour.What reducing agent was selected can be liquefied ammonia, ammoniacal liquor, urea liquid containing ammonia solution.SCR reaction zones are arranged on boiler smoke
In road, inside includes catalyst layer.
A kind of SNCR-SCR that the present invention is provided combines the design method of flue gas denitrification system technique, comprises the following steps：
(1) number that the calculating of reducing agent volume flow rate and catalyst volume for setting up SNCR-SCR combined denitration techniques are calculated
Learn model；
(2) temperature that the NOx concentration information in flue gas, the flow of flue gas and flue gas are obtained by measuring instrument measurement is believed
Breath；
(3) reducing agent volume flow rate and catalyst volume are calculated with reference to the information and mathematical modeling that measurement is obtained；
In the mathematical modeling, reducing agent volume flow rate υ calculation formula is：
Wherein, ρ is the density of reductant solution, and M is the molal weight of reducing agent, MNOxFor the molar average of NOx in flue gas
Quality, q is the exhaust gas volumn of boiler, ηNOxFor NOx clearance, NOxinFor the concentration of the NOx in flue gas, ASR be reducing agent with
NOx actual stoichiometric ratio；
In the mathematical modeling, catalyst volume VcatalystCalculation formula be：
Vcatalyst=α × qSCR×ηadj×slipadj×NOxadj×Tadj÷nSCR
Wherein, α is regulation coefficient, and experience span is 2.5≤α≤3.0, can also be had according to fitting experimental data
Body numerical value, qSCRFor exhaust gas volumn, η in SCR reactorsadjFor adjustment denitration efficiency, slipadjFor adjustment the escaping of ammonia rate, NOxadjFor
Adjust NOx concentration, TadjFor adjustment temperature, nSCRFor SCR reactor quantity.
Preferably, the reducing agent and NOx actual stoichiometric ratio ASR=β NSR, NSR are reducing agent and NOx
Stoichiometric ratio,β is empirical parameter, 1≤β≤3.
Preferably, the adjustment denitration efficiency ηadjFor ηadj=0.2809+ (1.058 × ηNOx)；The adjustment the escaping of ammonia
Rate slipadjFor slipadj=1.2835- (0.0568 × slip), wherein slip are theoretical the escaping of ammonia rate slip=ASR-0.8；
The adjustment NOx concentration NOxadjFor NOxadj=0.1542+ (0.3208 × NOxin)；The adjustment temperature is Tadj=15.16-
(0.03937×T)+(2.74×10-5×T2), T be porch flue-gas temperature, unit for °F.
Preferably, the calculation formula of the SCR reactors quantity is：qfluegasFor the flowing of flue gas
Speed, is obtained by flow measurement, or according to formulaCalculating is obtained, qquelFor volumetric fuel flow rate, T
For porch flue-gas temperature, n'SCRFor reactor predetermined number.
Beneficial effect：The present invention is contained by setting up rational " SNCR-SCR combined denitrations technique " mathematical modeling to solve
The volume flow rate of ammonia reducing agent and the volume of design catalyst, it is possible to increase the denitration efficiency of medium small boiler, reduce SCR catalysis
The size of agent, reduces the probability of catalyst poisoning, reduces input cost.
Brief description of the drawings
Fig. 1 is flow chart of the method for the present invention.
Embodiment
With reference to specific embodiment, the present invention is furture elucidated, it should be understood that these embodiments are merely to illustrate the present invention
Rather than limitation the scope of the present invention, after the present invention has been read, various equivalences of the those skilled in the art to the present invention
The modification of form falls within the application appended claims limited range.
A kind of SNCR-SCR combines the design method of flue gas denitrification system technique disclosed in the embodiment of the present invention, mainly includes
SNCR and SCR reacts the process parameters design of two parts, sets up the number for solving reducing agent volume flow rate in SNCR parts respectively
Model is learned, the theoretical value of reducing agent volume flow rate is obtained by calculating；In SCR parts, the theoretical value of catalyst volume is calculated.For
There is provided theoretical foundation and reference for the design of SNCR-SCR joint flue gas denitrification systems.
As shown in figure 1, the process design method of the present invention mainly includes：First, SNCR-SCR combined denitration techniques are set up
Reducing agent volume flow rate calculate and catalyst volume calculate mathematical modeling；Then flue gas is obtained by measuring instrument measurement
In NOx concentration information, the temperature information of the flow of flue gas and flue gas；The information and mathematical modeling finally obtained with reference to measurement
Calculate reducing agent volume flow rate and catalyst volume.
First, the volume flow rate design of SNCR reducing agents
The volume flow rate υ (g/h) of reducing agent：
In formula：The density of ρ-reductant solution, g/L；(density can be obtained by densitometer direct measurement)
M-reducing agent straying quatity, g/h.
Reducing agent straying quatity m：
In formula：The molal weight of M-reducing agent, kg/mol；
MNOx- NOx average molar mass, kg/mol；(nitrogen-oxide analyzer, is used, result is obtained according in flue gas
NO、NO2Deng content estimated)
The exhaust gas volumn of q-boiler；Unit Nm3/h.(measurement of flue gas flow meter can be obtained)
- NOx clearance；
NOxinThe concentration of NOx in-flue gas, mg/m3；(nitrogen-oxide analyzer, can be obtained)
The actual stoichiometric ratio of ASR-reducing agent and NOx.
The calculating of NOx clearances
In formula：NOxinThe concentration of NOx in-flue gas, mg/m3；
NOxoutThe concentration of NOx in-discharge flue gas, mg/m3；(nitrogen-oxide analyzer, can be obtained) reducing agent and NOx's
Actual stoichiometric ratio ASR：
ASR=β NSR (4)
β is empirical parameter, value (1~3), can be adjusted according to the type of reducing agent, Burners Positions
The stoichiometric ratio NSR of reducing agent and NOx
Using formula (3) (4) (5), it can calculate and obtainASR, then by nitrogen-oxide analyzer, flue gas flow meter
Formula (2) is substituted into the data that densitometer is measured, you can obtain the volume flow rate υ of reducing agent.
2nd, the size design of SCR catalyst
(1) catalyst volume Vcatalyst(m3)
Vcatalyst=2.81 × qSCR×ηadj×slipadj×NOxadj×Tadj÷nSCR (6)
In formula：According to fitting experimental data value 2.81 in α-regulation coefficient, the present embodiment, according to different hits
The value that strong point is likely to be obtained is different, and usual scope is between 2.5~3.0.
qSCRExhaust gas volumn in-SCR reactors, m3/h；
ηadj- adjustment denitration efficiency, ηadj=0.2809+ (1.058 × ηNOx)；(ηNOxIt can be calculated by formula 3)
slipadj- adjustment the escaping of ammonia rate, slip=1.2835- (0.0568 × slip)；Theoretical the escaping of ammonia rate Slip=(ASR-0.8)
NOxadj- adjustment NOx concentration, mg/Nm3,NOxadj=0.1542+ (0.3208 × NOxin)；
Tadj- adjustment temperature,Tadj=15.16- (0.03937 × T)+(2.74 × 10-5×
T2)
Concrete numerical value in the calculation formula of above-mentioned adjusting parameter is that can reach the empirical value of more excellent calculating effect, can root
Realize that data the Fitting Calculation is drawn according to multigroup, in practical application, concrete numerical value also can be adjusted suitably.
nSCR- reactor quantity
Flow of flue gas rate
In formula：qfluegasThe flow rate of-flue gas, ft3/min(1ft3=0.028m3)；(utilizable flow is measured)
qquel- volumetric fuel flow rate, ft3/min；(being obtained by feeding control)
T-porch flue-gas temperature,(temperature measuring set is obtained)
n'SCR- reactor predetermined number (generally 1~3).
It is the volume that can obtain required catalyst by parameters substitution formula (6).
It is about below 2x10 with certain exhaust gas volumn5Nm3Exemplified by/h fire coal boiler fume denitration improvement project, illustrate this hair
Application effect of the bright mathematical modeling in actual engineering design.Coal selects lignite in the engineering, big from specific surface area
TiO2For carrier, V2O5For the flat catalyst of active component.Reducing agent uses urea liquid.
Fume emission performs standard：Fossil-fuel power plant atmospheric pollutant emission standard GB13223-2011
Emission standard of air pollutants for boilers GB13271-2014
Design initial parameter as shown in table 1,
Table 1 designs initial parameter
The mathematical modeling set up according to embodiments of the present invention, and the data parameters measured are calculated, and can be gone back
Former agent volume flow rate is 718.56L/h, and the volume of catalyst is 17.2m3, it is consistent with the case history data of actual motion.Cause
The design actual to engineering of this mathematical modeling of the invention possesses the effect of theoretical calculation and reference.
Claims (1)
1. a kind of SNCR-SCR combines the design method of flue gas denitrification system technique, it is characterised in that comprise the following steps：
(1) mathematical modulo that the calculating of reducing agent volume flow rate and catalyst volume for setting up SNCR-SCR combined denitration techniques are calculated
Type；
(2) temperature information of NOx concentration information in flue gas, the flow of flue gas and flue gas is obtained by measuring instrument measurement；
(3) reducing agent volume flow rate and catalyst volume are calculated with reference to the information and mathematical modeling that measurement is obtained；
In the mathematical modeling, reducing agent volume flow rate υ calculation formula is：
Wherein, ρ is the density of reductant solution, and M is the molal weight of reducing agent, MNOxFor the molar average matter of NOx in flue gas
Amount, q is the exhaust gas volumn of boiler, ηNOxFor NOx clearance, NOxinFor the concentration of the NOx in flue gas, ASR is reducing agent and NOx
Actual stoichiometric ratio；
In the mathematical modeling, catalyst volume VcatalystCalculation formula be：
Vcatalyst=α × qSCR×ηadj×slipadj×NOxadj×Tadj÷nSCR
Wherein, α is regulation coefficient, 2.5≤α≤3.0, qSCRFor exhaust gas volumn, η in SCR reactorsadjTo adjust denitration efficiency,
slipadjFor adjustment the escaping of ammonia rate, NOxadjFor adjustment NOx concentration, TadjFor adjustment temperature, nSCRFor SCR reactor quantity；
The actual stoichiometric ratio ASR=β NSR of the reducing agent and NOx, NSR are reducing agent and NOx stoichiometric ratio,β is empirical parameter, 1≤β≤3；
The adjustment denitration efficiency ηadjFor ηadj=0.2809+ (1.058 × ηNOx)；The adjustment the escaping of ammonia rate slipadjFor
slipadj=1.2835- (0.0568 × slip), wherein slip are theoretical the escaping of ammonia rate slip=ASR-0.8；The adjustment NOx
Concentration NOxadjFor NOxadj=0.1542+ (0.3208 × NOxin)；The adjustment temperature is Tadj=15.16- (0.03937 × T)
+(2.74×10-5×T2), T be porch flue-gas temperature, unit for °F；
The calculation formula of the SCR reactors quantity is：qfluegasFor the flow rate of flue gas, pass through flow
Measure, or according to formulaCalculating is obtained, qquelFor volumetric fuel flow rate, T is porch
Flue-gas temperature, n'SCRFor reactor predetermined number.
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| CN106524205B (en) * | 2016-09-14 | 2021-04-02 | 科林环保技术有限责任公司 | Ultra-low emission purification equipment for flue gas of coal-fired industrial furnace |
| CN109935279B (en) * | 2018-12-29 | 2023-09-15 | 国电环境保护研究院有限公司 | Power plant SCR denitration catalyst volume design calculation method |
| CN113877389B (en) * | 2020-07-01 | 2023-06-23 | 中冶长天国际工程有限责任公司 | Control method of SNCR-SCR coupling denitration system of chain grate machine-rotary kiln system |
| CN113908677B (en) * | 2020-07-10 | 2022-12-06 | 中冶长天国际工程有限责任公司 | Flue gas treatment process and treatment system |
| CN112403230B (en) * | 2020-11-17 | 2022-05-06 | 江苏绿都环境工程有限公司 | Denitration method based on SNCR and SCR mixed technology |
| CN114159971B (en) * | 2021-11-25 | 2023-11-24 | 山西太钢工程技术有限公司 | Feed-forward automatic control method for ultralow emission of nitrogen oxides based on SCR (selective catalytic reduction) method |
| CN116139667B (en) * | 2022-11-23 | 2024-04-09 | 清华大学 | Denitration reducing agent double-stage linkage control method and device, electronic equipment and storage medium |
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| CN103605877B (en) * | 2013-07-31 | 2016-12-28 | 广东电网公司电力科学研究院 | The catalyst updating screening technique of SCR denitration system and system thereof |
| CN103752170B (en) * | 2014-01-16 | 2015-08-19 | 华中科技大学 | A kind of tangential firing pulverized-coal fired boiler SCR system denitration running optimizatin method |
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