Background technology
At present, the commonly used scr denitrification apparatus of large-scale coal fired power plant are reducing nox concentration of emission in flue gas.Scr utilizes
nh3Nox is reduced to the n of environmental sound in the presence of catalyst by the reduction characteristic to nox2And h2o.In actual motion mistake
Cheng Zhong, the control of ammonia spraying amount is particularly critical, increases ammonia spraying amount and advantageously reduces nox concentration of emission, but the escaping of ammonia rate can increase therewith
Plus, and then easily cause downstream air preheater and block and corrode it is also possible to causing electric precipitation polar curve dust stratification, removing because ammonium hydrogen sulfate deposits
Dirt cloth bag sticks the adverse effects such as ash.
In spray ammonia control aspect, on the one hand require rationally to control spray ammonia total amount, on the other hand require to ensure spray ammonia uniformity
(referring mainly to ammonia nitrogen mol ratio relatively uniform), to guarantee allowing in the range of the escaping of ammonia rate, nox concentration of emission is up to standard.
Spray ammonia overall control typically using scr outlet nox concentration measurement as feedback signal, adjusts spray ammonia overall control valve
(typically every side 1).But current scr exports commonly used spot measurement nox concentration;The representativeness of spot measurement value is poor, no
Can reflect that scr exports the situation of nox mean concentration, therefore whether can not characterize spray ammonia total amount completely suitable.Additionally, current scr goes out
Mouth nox concentration commonly used cems measurement, also haves such problems as that lag time length, maintenance workload are big.
Spray ammonia uniformity typically need to spray ammonia by manually adjusting some sprays ammonia manual modulation valves (typically every side 8~40)
Manual modulation valve is located at the downstream of spray ammonia overall control valve, and the Main Basiss of its adjustment are that field measurement scr outlet nox concentration is divided
Cloth.The higher region of local nox concentration, the spray ammonia manual modulation valve of corresponding upstream aig (spray ammonia adjusting apparatus) increases to be opened
Degree, on the contrary then reduce aperture, ensure that scr exports nox concentration distribution by repeated multiple times adjustment relatively uniform.If now scr urges
Agent module does not exist significantly weares and teares, caves in and blocks up the faults such as ash, then explanation spray ammonia uniformity is ensured.
Above-mentioned spray ammonia total amount is realized automatically controlling, but spray ammonia uniformity also relies primarily on and periodically manually adjusts, adjustment
Purpose is to realize scr entrance section zones of different ammonia nitrogen mol ratio to reach unanimity, so that scr outlet zones of different
Nox concentration deviation is little.Due to once complete aig adjustment process take longer, expend larger, therefore coal fired power plant is typically every
Year adjusts once, and outer completing of mostly entrusting.
Because in the adjustment cycle, aig characteristic is basically unchanged, when burning coal type change, mill compound mode change, burn
When the factors such as device adjustment lead to scr entrance nox concentration distribution and flow field that significant change occurs, the uniformity of ammonia nitrogen mol ratio will be bright
Aobvious variation, that is, local ammonia nitrogen mol ratio and the deviation of meansigma methodss become big;The too small region of ammonia nitrogen mol ratio, local denitration efficiency is not
Can be up to standard, and the excessive region of ammonia nitrogen mol ratio, the escaping of ammonia rate is exceeded.
Before minimum discharge transformation, coal fired power plant executes special discharge standard, and denitration efficiency is generally in 60%~80%
Between, that is, ammonia nitrogen mol ratio meansigma methodss generally control between 0.6~0.8;And after minimum discharge transformation, nox concentration of emission will
Ask and be strict controlled in 50mg/nm3Hereinafter, unit scr denitration efficiency exceedes often beyond 90%, i.e. ammonia nitrogen mol ratio meansigma methodss
0.9.When the factors such as burning coal type change, mill compound mode change, burner adjustment lead to scr entrance nox concentration distribution and stream
When field occurs significant change, execution minimum discharge standard will lead to the position that ammonia nitrogen mol ratio is more than 1 will greatly increase, the escaping of ammonia
Rate will far super permissible value (< 3ppm), thus easily causing air preheater to block up the adverse effect such as ash, electric precipitation polar curve dust stratification.
Content of the invention
In order to solve an a series of above-mentioned difficult problem, the present invention provides a kind of scr denitrification apparatus, its spray ammonia adjusting means and its spray
Ammonia method of adjustment.
For solving above-mentioned technical problem, the technical scheme is that
A kind of scr denitrification apparatus spray ammonia adjusting means, including spray ammonia main pipe;Spray ammonia main pipe branches into the spray of more than two
Ammonia subregion main pipe, every sprays the spray ammonia arm that ammonia subregion main pipe branches into more than two;Respectively it is provided with every spray ammonia arm
Spray ammonia manual modulation valve, every spray ammonia subregion main pipe is respectively provided with spray ammonia district grid valve, the spray ammonia main pipe before non-branch
Upstream section is provided with the spray total adjustable valve of ammonia.
Spray ammonia main pipe Upstream section before above-mentioned non-branch refers to spray the initiating terminal of ammonia main pipe, namely spray ammonia main pipe does not branch into spray
Part before ammonia subregion main pipe;Respectively it is provided with spray ammonia district grid valve in every spray ammonia subregion main pipe, that is, spray ammonia district grid
Valve is corresponded with spray ammonia subregion main pipe, adjusts the ammonia amount being entered spray ammonia subregion main pipe by spray ammonia main pipe.
Further preferred as the application, spray ammonia main pipe branches into 3~5 spray ammonia subregion main pipes.
Each spray ammonia subregion main pipe is parallel with one another, namely each spray ammonia total adjustable valve downstream sets 3~5 spray ammonia district grid
Valve, each spray ammonia district grid valve is in parallel;Every spray ammonia subregion main pipe branches into one group of spray ammonia arm.
Applicant further study show that, the flue cross section due to scr denitrification apparatus is more than vertical height for horizontal width
Rectangular-shaped, and width is generally 3~5 times of height it is considered to ammonia enters the rule of mixing and diffusion in flue gas, is divided into 3~5
Relatively independent region precise controlling ammonia spraying amount, can greatly improve spray ammonia uniformity.If number of partitions increases further, not only throw
Money cost can increase therewith, and system reliability can decline therewith, and therefore, applicant is preferably spray ammonia some in prior art
Manual modulation valve and spray ammonia arm are divided into 3~5 groups.
A kind of scr denitrification apparatus, including denitrification apparatus body, denitrification apparatus body includes scr flue entrance and scr flue
Outlet, also comprises above-mentioned scr denitrification apparatus spray ammonia adjusting means and scr outlet nox concentration monitoring device;
Scr denitrification apparatus spray ammonia adjusting means is arranged on outside scr flue entrance, and sprays ammonia into scr denitrification apparatus;
Scr outlet nox concentration monitoring device includes multiple spot mixed sampling device and nox in-line analyzer, and multiple spot mixing takes
Sampling device includes multidraw section, transition linkage section and the smoke mixing section being sequentially communicated;Multidraw section is located at scr flue and goes out
Mouthful, smoke mixing section is connected with air preheater flue outlet;Nox in-line analyzer is arranged in smoke mixing section.
Denitrification apparatus body and air preheater are existing equipment commonly used in the art, unnecessary for avoiding, and excessively do not describe.
Typically every Thermal generation unit has two scr denitrification apparatus, is traditionally referred to as in the industry a side and b side.
The application spray ammonia district grid valve can remote manual or automatically adjust, preferably automated regulation, the foundation of regulation is upper
State multiple spot mixed sampling device areal sampling, each subregion nox mean concentration measuring successively through nox in-line analyzer.
In order to be further ensured that accuracy and the convenience of nox measurement, the multidraw section of multiple spot mixed sampling device is by 6
~12 multidraw rifle compositions;Transition linkage section includes and multidraw rifle same amount of sampling arm, multidraw rifle
Correspond with sampling arm, the corresponding sampling arm connection of every multidraw rifle, every sampling arm is equipped with
Sampling control valve;Smoke mixing section includes sampling main pipe, and all of sampling arm converges to sampling main pipe, and sampling main pipe is provided with
Nox in-line analyzer;Multidraw rifle is arranged along scr flue outlet width, and sampling main pipe is with air preheater flue outlet even
Logical.
Preferably, above-mentioned multidraw rifle the arrangement quantity of width and position according to the number of upstream ammonia-spraying grid and
Depending on the arrangement of space, further preferably, the area equation that every corresponding ammonia-spraying grid of multidraw rifle covers;Spray ammonia lattice
Grid are equal with spray ammonia manual modulation valve quantity, one-to-one corresponding.
Above-mentioned ammonia-spraying grid is existing usual means in scr denitrification apparatus.
In order to further ensure that the uniformity of spray ammonia, spray ammonia arm is divided into 3~5 groups;Sampling arm is divided into 3~5 groups, sprays ammonia
The group number of arm is consistent and mutually corresponding with the group number of sampling arm.
Above-mentioned spray ammonia arm is divided into 3~5 groups, namely spray ammonia main pipe branches into 3~5 spray ammonia subregion main pipes, every spray ammonia
The corresponding one group of spray ammonia arm of subregion main pipe.
When opening one of which and sampling the sampling control valve on arm and close other groups, then automatically extract respective partition
Flue gas aggregate sample, thus learn nox removal effect in this subregion.
Above-mentioned sampling control valve opens and closes successively by group, can record scr and export each subregion nox mean concentration, from
And it is control and the regulation offer foundation of above-mentioned spray ammonia district grid valve.
Above-mentioned sampling control valve opens and closes successively one by one, can record different positions on scr flue outlet width
Put nox concentration distribution situation, thus manually adjusting offer foundation for the scene of above-mentioned spray ammonia manual modulation valve.
Opened and closed successively by sampling control valve, realization patrols survey to scr outlet nox concentration distribution, and it is prominent excellent
Gesture is embodied in: only measures each point or each subregion nox concentration with a set of nox in-line analyzer, not only reduces investment and safeguard work
Measure, and nox in-line analyzer itself meter error affects very on the evaluation of scr flue outlet nox uniform concentration distribution
Little, be conducive to improving total system reliability and degree of regulation.
Above-mentioned sampling control valve opens and closes successively by group, is conducive to shortening and patrols the time surveying one time, thus reduce patrolling
The possibility to flue gas flow field and the impact of nox concentration distribution for the working conditions change during survey, and then be conducive to improving spray ammonia district grid
The control of valve and degree of regulation.
Above-mentioned sampling control valve opens and closes successively one by one, patrols and surveys time of one time and accordingly extend, but surveys under this pattern
Amount data is not used to system and automatically adjusts, but guide field manually adjusts spray ammonia manual modulation valve, participant during adjustment
Member can manual intervention, be also convenient for judging the stability of operating mode, therefore, patrol under this pattern survey scr export nox concentration be distributed in detail
The effectiveness of data is still ensured.
Above-mentioned a set of multiple spot mixed sampling device, by sampling the different working modes switching of control valve, realizes taking respectively
It is engaged in, in spray ammonia partitioning control valve and spray ammonia hand control valve, if excavating its expanded function further, also to serve spray ammonia total amount
Control valve, is " killing three birds with one stone ", specific implementation is: takes on the sampling arm of multiple spot mixed sampling device and each sampling
The upstream of control valve, connects a sampling bypass branch respectively, and each bypass branch is collected to sampling bypass main pipe, female in sampling bypass
Nox concentration is surveyed on pipe.
For retrofitted unit, it is investment reduction it is preferable that the above-mentioned sampling of former cems systematic survey that reuses bypasses nox in main pipe
Concentration.
In order to improve the automaticity of system it is preferable that scr outlet nox concentration monitoring device, also include collection and control
Module, collection and control module at least receive nox in-line analyzer and the transmission signal of sampling control valve.Collection and control module
Realize with reference to existing known technology in row.
The direction in downstream namely the direction of flow of flue gas are swum on the application.
In order to prepare conveniently, cost-effective, ensure simultaneously the convenience sampling with accuracy it is preferable that multiple spot mixed sampling
Device is made using the tubing that internal diameter is 20~100mm, and that is, cross section (flow area) is circle.
In order to take into account representativeness and the real-time of smoke sampling, and prevent thief hole from blocking up ash it is preferable that multidraw section takes
Sample hole is circular hole, and the internal diameter of thief hole is 6~18mm, and thief hole is evenly arranged along the length direction of multidraw section, Ye Jiqu
Multidraw section is divided into the n+1 section of equal length by sample hole, and n is sampling hole number.
Further preferably, thief hole at least 3 and back of the body air-flow setting, the circulation area summation of all thief holes is not more than
The 40% of multidraw section actual internal area.
Air-flow is met in multidraw section wall side, and opposite side carries on the back air-flow, and thief hole is arranged on back of the body air-flow side, can try one's best
Down-sample the dust content of flue gas.
Block up the possibility of ash in order to reduce above-mentioned multidraw device further, scr exports nox concentration monitoring device, also wraps
Include hot blast blowback subsystem, the preferred heat primary air of source of the gas of hot blast blowback subsystem.Above-mentioned hot blast blowback subsystem at least includes
Blowback pipeline, blowback control valve and blowback isolating valve, blowback isolating valve is located in smoke mixing section, and blowback control valve is located at blowback
On pipeline, and blowback pipeline connects smoke mixing section, is located at blowback isolating valve upstream.When come into operation hot blast blowback subsystem when, instead
Blow isolating valve closing, blowback control valve is opened;And during measuring system bringing normally into operation, blowback isolating valve is opened, blowback control valve is closed
Close.
In order to convert nox concentration distribution under benchmark oxygen amount, scr exports nox concentration monitoring device, also includes o2On-line analyses
Instrument, o2In-line analyzer is also provided in smoke mixing section.Preferably, o2In-line analyzer and the integrated use of nox in-line analyzer.
Export the reliability of nox concentration monitoring device in order to improve above-mentioned scr it is preferable that nox in-line analyzer is straight cutting
Formula, using semiconductive ceramic gas sensor, can be under flue gas environment below 500 DEG C for the long-term work.
The spray ammonia method of adjustment of above-mentioned scr denitrification apparatus, exports, according to scr, the nox obtaining in nox concentration monitoring device dense
Degree, controls spray ammonia total using the spray total adjustable valve of ammonia, spray ammonia district grid valve and spray ammonia manual modulation valve three-level regulating valve series connection
Amount and uniformity.
Using periodicity self-regulation mode, during each period modulation, ensure the average of all spray ammonia district grid valves
Aperture is basically unchanged.I.e. while reducing aperture, part spray ammonia district grid valve increases part spray ammonia district grid valve therewith
Aperture, and the amplitude that reduces is roughly the same with the amplitude of increase.
Applicant it has been investigated that, prior art to adjust spray using " spray ammonia overall control valve+spray ammonia manual modulation valve "
Ammonia total amount and spray ammonia uniformity, do not adapt to the strict demand of minimum discharge, and therefore novelty proposes " spray ammonia overall control valve
The technical scheme of+spray ammonia district grid valve+spray ammonia manual modulation valve ".
For ensureing the uniformity of spray ammonia, take into account reliability and the promptness of adjustment, preferably the spray ammonia side of optimizing and revising simultaneously
Method is: comprises the steps:
A, scr flue outlet is approximately divided into 3~5 subregions, patrols survey using scr outlet nox concentration monitoring device each
Subregion nox mean concentration, that is, sample control valve and open and close by group successively;
B, the nox mean concentration measured value on-line automatic adjustment spray ammonia district grid valve according to step a gained, each to ensure
Subregion nox mean concentration approximately equal, wherein, spray ammonia district grid valve sets aperture regulation interval, that is, limit the upper limit and lower limit,
When needing out-of-limit regulation ability leveling each subregion nox mean concentration, just prompting need to carry out spraying the artificial tune of ammonia manual modulation valve
Whole, before manually adjusting spray ammonia manual modulation valve, first spray ammonia district grid valve is manually set in the interval centre of aperture regulation
Position, that is, the upper limit and the intermediate valve position of lower limit, are then switched to sample the pattern that control valve opens and closes successively one by one, obtain
Take more detailed scr outlet nox concentration distribution data, refinement adjustment spray ammonia manual modulation valve, to ensure scr flue outlet width
As far as possible uniformly, adjustment switches spray ammonia district grid valve to auto state to degree direction nox concentration distribution again after finishing.
The technological thought that above-mentioned spray ammonia optimizes and revises method embodiment is: coarse adjustment spray ammonia district grid valve automatically, to adapt to scr
Inlet flue gas flow field and the change of nox concentration distribution, thus improving the uniformity of scr entrance ammonia nitrogen mol ratio, namely are based on scr
Catalyst maximum denitration ability improves the uniformity that scr exports nox concentration distribution;When in certain valve opening interval range,
Automatically coarse adjustment spray ammonia district grid valve, it cannot be guaranteed that scr outlet nox concentration distribution is relatively uniform, that is, illustrates scr inlet flue gas
The change of flow field and nox concentration distribution is very greatly it is necessary to ammonia manual modulation valve is sprayed in manual fine tuning, thus realization adjustment spray on demand
Ammonia uniformity.
The NM technology of the present invention is all with reference to prior art.
The spray ammonia method of adjustment of scr denitrification apparatus of the present invention, by exporting nox mean concentration and nox concentration distribution to scr
It is monitored, General Promotion sprays the quality that ammonia controls, including the accuracy improving spray ammonia uniformity and lifting spray ammonia overall control,
The emphasis of whole system design aspect is highly integrated, has the significant advantages such as reduced investment, reliability height.
Embodiment 1
Scr denitrification apparatus as shown in Figure 2 spray ammonia adjusting means, including spray ammonia main pipe;Spray ammonia main pipe branches into three
Spray ammonia subregion main pipe, every spray ammonia subregion main pipe branches into three spray ammonia arms;Respectively it is provided with spray ammonia on every spray ammonia arm
Manual modulation valve, every spray ammonia subregion main pipe is respectively provided with spray ammonia district grid valve, the spray ammonia main pipe before non-branch sets
There is the spray total adjustable valve of ammonia.
Scr denitrification apparatus as shown in Figure 3, including denitrification apparatus body, denitrification apparatus body include scr flue entrance and
Scr flue outlet, also comprises above-mentioned scr denitrification apparatus spray ammonia adjusting means and scr outlet nox concentration monitoring device;
Scr denitrification apparatus spray ammonia adjusting means is arranged on outside scr flue entrance, and sprays ammonia into scr denitrification apparatus;
Scr outlet nox concentration monitoring device includes multiple spot mixed sampling device and nox in-line analyzer, and multiple spot mixing takes
Sampling device includes multidraw section, transition linkage section and the smoke mixing section being sequentially communicated;Multidraw section is located at scr flue and goes out
Mouthful, smoke mixing section is connected with air preheater flue outlet;Nox in-line analyzer is arranged in smoke mixing section.
The multidraw section of above-mentioned multiple spot mixed sampling device is made up of 9 multidraw rifles;Transition linkage section include with
Multidraw rifle same amount of sampling arm, multidraw rifle and sampling arm correspond, every multidraw rifle and its
Corresponding sampling arm connection, every sampling arm is equipped with sampling control valve;Smoke mixing section includes sampling main pipe, owns
Sampling arm converge to sampling main pipe, sampling main pipe is provided with nox in-line analyzer;Multidraw rifle is along scr flue outlet
Width is arranged, and sampling main pipe is connected with air preheater flue outlet.
Above-mentioned multidraw rifle is in the arrangement quantity of width and position according to the number of upstream ammonia-spraying grid and space
Depending on arrangement, the area equation that every corresponding ammonia-spraying grid of multidraw rifle covers;Ammonia-spraying grid is adjusted manually with spray ammonia
Section valve quantity is equal, one-to-one corresponding.
Above-mentioned ammonia-spraying grid is existing usual means in scr denitrification apparatus.
Above-mentioned spray ammonia arm has 3 groups;Sampling arm have 3 groups, spray ammonia arm group number with sample arm group number consistent and
Mutually corresponding.
When opening one of which and sampling the sampling control valve on arm and close other groups, then automatically extract respective partition
Flue gas aggregate sample, thus learn nox removal effect in this subregion.
Above-mentioned sampling control valve opens and closes successively by group, can record scr and export each subregion nox mean concentration, from
And it is control and the regulation offer foundation of above-mentioned spray ammonia district grid valve.
Above-mentioned sampling control valve opens and closes successively one by one, can record different positions on scr flue outlet width
Put nox concentration distribution situation, thus manually adjusting offer foundation for the scene of above-mentioned spray ammonia manual modulation valve.
Multiple spot mixed sampling device adopts the tubing that internal diameter is 80mm to make, and the tube wall of multidraw rifle is provided with sampling
Hole;Thief hole is circular hole, and the internal diameter of thief hole is 12mm, thief hole at least 3 and carry on the back air-flow along the length side of multidraw rifle
To being evenly arranged, the circulation area summation of all thief holes is not more than the 40% of multidraw rifle cross-sectional area;
Above-mentioned multiple spot mixed sampling device is taken also to include o2In-line analyzer, o2In-line analyzer and nox in-line analyzer collection
Become to use, be located in smoke mixing section.
Above-mentioned nox in-line analyzer be direct insertion, using semiconductive ceramic gas sensor, can long-term work at 500 DEG C
Under following flue gas environment.
The spray ammonia method of adjustment of above-mentioned scr denitrification apparatus, exports, according to scr, the nox obtaining in nox concentration monitoring device dense
Degree, controls spray ammonia total using the spray total adjustable valve of ammonia, spray ammonia district grid valve and spray ammonia manual modulation valve three-level regulating valve series connection
Amount and uniformity, specifically include following steps:
A, scr flue outlet is approximately divided into 3 subregions, patrols each subregion of survey using scr outlet nox concentration monitoring device
Nox mean concentration, that is, sample control valve and open and close by group successively;
B, the nox mean concentration measured value on-line automatic adjustment spray ammonia district grid valve according to step a gained, each to ensure
Subregion nox mean concentration approximately equal, wherein, it is 60%~80% that spray ammonia district grid valve sets aperture regulation interval, that is, limit
Determine the upper limit be 80%, lower limit be 60%, when need out-of-limit regulation could leveling each subregion nox mean concentration when, just point out to enter
Manually adjusting of row spray ammonia manual modulation valve, before manually adjusting spray ammonia manual modulation valve, manual spraying ammonia district grid valve first
It is set in the interval centre position of aperture regulation, that is, 70%, it is then switched to sample what control valve opened and closed successively one by one
Pattern, obtains more detailed scr and exports nox concentration distribution data, refinement adjustment spray ammonia manual modulation valve, to ensure scr cigarette
As far as possible uniformly, adjustment switches spray ammonia district grid valve to auto state to road outlet width nox concentration distribution again after finishing.