CN209020167U - A kind of device for adjusting denitration spray ammonia flow adding feedforward based on cascade PID - Google Patents
A kind of device for adjusting denitration spray ammonia flow adding feedforward based on cascade PID Download PDFInfo
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Abstract
The utility model relates to a kind of devices for adjusting denitration spray ammonia flow for adding feedforward based on cascade PID.Existing denitration spray ammonia automatically controls logic and is difficult to steadily control SCR reactor outlet NOxConcentration increases the labor intensity of operations staff.The utility model includes SCR reactor, electric control valve and flowmeter etc., and SCR reactor is arranged between boiler economizer and air preheater；SCR reactor inlet is adjacently positioned with boiler economizer, and SCR reactor outlet is adjacently positioned with air preheater；No.1 ammonia-spraying grid, deflector, No. two ammonia-spraying grids and catalyst layer are sequentially arranged along the flow direction of flue gas, and No.1 ammonia-spraying grid is adjacently positioned with SCR reactor inlet, and No. two ammonia-spraying grids and catalyst layer are adjacently positioned.The utility model can overcome control problem brought by the big retardation characteristic of denitrating system, reduce control overshoot, can be realized accurately controlling for ammonia spraying amount.
Description
Technical field
The utility model relates to a kind of devices for adjusting denitration spray ammonia flow for adding feedforward based on cascade PID, belong to thermal technology
Automation field.
Background technique
Under the background of current power industry new energy large-scale grid connection, fired power generating unit frequently participates in peak regulation, and peak regulation is deep
It spends increasing.Therefore, boiler operatiopn operating condition is in a wide range of frequently variation, so that furnace outlet flue gas parameter frequently changes, packet
Include SCR denitration entrance NOxConcentration variation is violent.Selective catalytic reduction flue gas denitration method (Selective Catalytic
Reduction), abbreviation SCR is most widely used a kind of method of denitration in current thermal power plant.SCR denitration principle is to be catalyzed
NH is utilized under the action of agent3By NOxIt is reduced to N2, the main chemical reactions of generation are as follows:
4NO+4NH3+O2→4N2+6H2O
The denitration spray ammonia in power plant generally adds feedforward control by using single pid loop at present, such as application No. is
201610235007.0 Chinese patent, PID (Proportion Integration Differentiation) loop modulation
SCR reactor outlet NOxConcentration, feedforward are generally unit load change rate.Denitration spray ammonia automatic adjustment effect under the control mode
Fruit is poor, it is often necessary to which operations staff intervenes, manually adjusts ammonia spraying amount, and ammonia spraying amount is caused to fluctuate big, Benitration reactor outlet NOx
Fluctuation of concentration is big.When the ammonia flow needed for practical ammonia spraying amount is less than operating condition, NO is easily causedxConcentration of emission is exceeded；When reality sprays ammonia
When amount is more than ammonia flow needed for operating condition, ammonia slip concentration is high, aggravates NH4HSO4Generation, easily cause air preheater corrosion or
Blocking.Furthermore denitrating system itself has the characteristics that big retardation, non-linear, time-varying, therefore automatic to unit SCR denitration spray ammonia
Adjusting optimizes research, improves spray ammonia automatic Control Quality, effectively controls chimney entrance NOxConcentration be used as always one very
Important research topic.
NOxFull name in English: nitrogen oxides, NOxChinese be: nitrogen oxides.Nitrogen oxides, that is, nitrogen and oxygen
Conjugate, including many kinds, such as nitric oxide, nitrogen dioxide etc..
Denitration spray ammonia automatic control logic adds feedforward control using single pid loop in general power plant, and pid loop adjusts SCR
Reactor outlet NOxConcentration, feedforward are generally unit load change rate.When ammonia pressure changes, single pid loop can not be fast
Speed measures the variation of ammonia flow, cannot quickly respond, and lag is serious.In addition, with the increase of unit load, SCR enters
Mouth NOxThe concentration overwhelming majority can reduce, sometimes also can random groups load increase and increase, therefore not according only to load changing rate
Easily determine that spray ammonia regulating valve should be opened big or reduce.So easily causing spray ammonia regulating valve according to general control logic
The fluctuation of large-amplitude sloshing, ammonia spraying amount exports NO so as to cause SCRxConcentration and chimney entrance NOxConcentration is fluctuated, often
More than required minimum discharge standard 50mg/m3, so that operations staff often artificially cuts manually, carry out human intervention.In addition,
AGC-R mode, unit load and SCR denitration entrance NO are in unitxWhen concentration changes violent, chimney entrance NOxConcentration is very
It is easy to appear concussion transmitting case, it is difficult to which steady control, operations staff also need to release automatic progress human intervention.This is not only reduced
The automatization level of subsidiary engine, also increases the labor intensity of operations staff.
Utility model content
The purpose of the utility model is to overcome the above deficiencies in the existing technologies, and provide a kind of structure design conjunction
The device for adjusting denitration spray ammonia flow for adding feedforward based on cascade PID of reason, the quick and precisely control of Lai Shixian ammonia spraying amount.
The technical scheme in the invention for solving the above technical problem is: a kind of adjusting adding feedforward based on cascade PID
The device, including SCR reactor, electric control valve and flowmeter etc. of ammonia flow are sprayed in denitration, and the SCR reactor is arranged in boiler
Between economizer and air preheater；The SCR reactor includes SCR reactor inlet, No.1 ammonia-spraying grid, deflector, two
Number ammonia-spraying grid, catalyst layer and SCR reactor outlet；The SCR reactor inlet is adjacently positioned with boiler economizer, described
SCR reactor outlet is adjacently positioned with air preheater；The No.1 ammonia-spraying grid, deflector, No. two ammonia-spraying grids and catalysis
Oxidant layer is sequentially arranged along the flow direction of flue gas, and the No.1 ammonia-spraying grid is adjacently positioned with SCR reactor inlet, and described two
Number ammonia-spraying grid and catalyst layer are adjacently positioned；Be provided on ammonia main pipe road in the SCR reactor electric control valve and
Flowmeter, the regulating valve are used to adjust the flow of ammonia, and the flowmeter is used to measure the flow of ammonia.
Furthermore, the catalyst layer is plate armature, and the catalyst layer is provided with 4 layers, every layer of catalyst
Layer is adjacent to be disposed with an ammonia-spraying grid.
Above-mentioned adds the working method for adjusting the device that ammonia flow is sprayed in denitration of feedforward as follows based on cascade PID: main PID is returned
The NO of road adjusting SCR reactor outletxConcentration, the output of main pid loop spray ammonia flow to theory after a correction function
It is modified, secondary pid loop adjusts ammonia supply flow, and the output of secondary pid loop is applied to spray ammonia plus the sum of four feedforwards
Flow control valve adjusts the size of ammonia spraying amount；Four feedforwards include the NO of SCR reactor outletxMeasured value reduces definite value deviation
Function, the function of unit load change rate, SCR reactor inlet NOxThe function of change rate of concentration and desulfurization export NOxIt is dense
The function of degree；Due to the inaccuracy of flue gas flow measurement, this working method creatively passes through main steam flow computational theory
Ammonia flow is sprayed, as shown in formula (1):
In formula: Q is ammonia flow needed for the SCR reactor theory of unilateral side, kg/h；CinFor the NO of SCR reactor inletxIt is dense
Degree, mg/m3；CoutsetFor the NO of SCR reactor outletxConcentration set point, mg/m3；QAAnd QBRespectively boiler first side main steam flow
Amount and second side main steam flow, t/h；A is coefficient, according to designed under unit rated load flue gas flow, main steam flow,
NO2Molal weight and NH3Molal weight is calculated.
The NO of SCR reactor outletxConcentration process values are after lead-lag module Leadlag1 as main pid loop
Process values, the NO of SCR reactor outletxSetting value of the concentration set point as main pid loop, main pid loop use positive interaction,
Proportional integration operation.
The output of main pid loop multiplied by theoretical ammonia spraying amount, i.e., repairs theoretical ammonia spraying amount after correction function f1 (x)
Just, correction factor range, that is, function f1 (x) output are as follows: a-b, a <b；Revised theory ammonia spraying amount is applied to adder ∑ 1
On, it is added with the manual amount of bias of operations staff, obtains actual needs ammonia spraying amount；Ammonia spraying amount will be actually needed again according to unit operating condition
Multiplied by coefficient B, that is, carry out marking the setting value after change is handled as secondary pid loop；Actually measured ammonia flow magnitude equally multiplies
With coefficient B, that is, carry out marking the process values after change is handled as secondary pid loop；Secondary pid loop uses reaction, proportional integration
Operation.
Conventional feed forward design is as follows:
The NO of one: SCR reactor outlet of feedforwardxConcentration process values are anti-with SCR after lead-lag module Leadlag1
The NO for answering device to exportxConcentration set point is subtracted each other, and is then scaled spray ammonia control valve opening size by function f2 (x), using
Amplitude limit link Lmt1, to ensure that role during adjusting spray ammonia control valve opening of feedforward one is moderate；
Feedforward two: unit load is applied on adder ∑ 2 all the way after lead-lag module Leadlag2, is made all the way
On the output action to adder ∑ 2 for using lead-lag module Leadlag3, Leadlag3, the two is subtracted each other as unit load
Then change rate is scaled spray ammonia control valve opening size, using amplitude limit link Lmt2, to ensure after function f3 (x)
Role during adjusting spray ammonia control valve opening of feedforward two is moderate；By the way that unit history is exchanged and observed with operations staff
Data find the NO of SCR reactor inlet in most casesxConcentration is reduced as unit load increases, with machine
It organizes load reduction and increases.Therefore consider most situations, i.e. setting function f3 (x) slope is negative, with unit load liter
It is high and reduce spray ammonia control valve opening, increase spray ammonia control valve opening as unit load reduces；
The NO of three: SCR reactor inlet of feedforwardxConcentration process values act on all the way after lead-lag module Leadlag4
Onto adder ∑ 3, it is applied to the output action of lead-lag module Leadlag5, Leadlag5 all the way to adder ∑ 3, two
Person subtracts each other the NO as SCR reactor inletxThen change rate of concentration is scaled spray ammonia regulating valve after function f4 (x) and opens
Size is spent, using amplitude limit link Lmt3, to ensure that role during adjusting spray ammonia control valve opening of feedforward three is moderate；
Feedforward four: desulfurization exports NOxConcentration process values are applied to function f5 after lead-lag module Leadlag6
(x), spray ammonia control valve opening size is scaled after function f5 (x), using amplitude limit link Lmt4, to ensure that feedforward four exists
Role is moderate during adjusting spray ammonia control valve opening.
Furthermore, unit is purged per will do it a CEMS every other hour, during purging, SCR reactor inlet
NOxThe NO of concentration and SCR reactor outletxConcentration remains unchanged；Therefore, during purging, main pid loop is no longer adjusted
Section, feedforward one and feedforward three remain unchanged, if having firing optimization, coal varitation, load variations or start and stop mill feelings during this
Condition easily causes the NO of SCR reactor outletxThe NO of concentration and chimney entrancexConcentration over-standard；Therefore it during CEMS purging, allows
Desulfurization exports NOxConcentration participates in adjusting；A handoff block T is provided in feedforward four, during CEMS is purged, desulfurization exports NOxIt is dense
Degree participates in adjusting, and after CEMS is purged, desulfurization exports NOxConcentration adjustment effect is reduced to zero.
The output of secondary pid loop is added on adder ∑ 4 jointly plus 4 feedforwards, using amplitude limit link Lmt5, limit
Width size is determined according to unit actual condition and operations staff's experience are comprehensive；It is applied to spray ammonia regulating valve after clipping, adjusts
Ammonia spraying amount size controls the NO of SCR reactor outletxConcentration and chimney entrance NOxConcentration.
The utility model compared with prior art, has the following advantages that and effect: the utility model proposes based on tandem
PID adds the device for adjusting denitration spray ammonia flow of feedforward, constructs predictable chimney entrance NOxThe mathematical model of concentration, can
More reflect Combustion Operation of Boilers in real time, feed-forward control signals are provided in time, adjusts ammonia spraying amount, denitrating system can be overcome big
Control problem brought by retardation characteristic reduces control overshoot, also reduces the escaping of ammonia under the premise of saving ammonia spraying amount, can
Realize accurately controlling for ammonia spraying amount.
Using the device for adjusting denitration spray ammonia flow for adding feedforward based on cascade PID of the utility model, can effectively avoid
At the end of CEMS purging, because SCR denitration exports NOxConcentration overshoot must seriously make to spray the generation that ammonia cuts manual case automatically.Separately
Outside, AGC-R mode, unit load and SCR denitration entrance NO are in unitxWhen concentration changes violent, the utility model dress
Ammonia spraying amount can be automatically adjusted by setting tracks denitration entrance NO in timexThe variation of concentration, so that chimney entrance NOxConcentration maintains to stablize.
Detailed description of the invention
Fig. 1 is the SCR denitration ammonia-gas spraying device structural schematic diagram of the utility model embodiment.
Fig. 2 is the denitration spray ammonia control strategy SAMA figure used in the utility model embodiment.
Fig. 3 be the utility model embodiment optimization before denitration spray ammonia Automatic Control Strategy SAMA figure.
Fig. 4 be the utility model embodiment optimization before the SCR reactor denitration of the side A spray ammonia self-regulation effect.
Fig. 5 be the utility model embodiment optimization before the SCR reactor denitration of the side B spray ammonia self-regulation effect.
Fig. 6 be the utility model embodiment optimization after the SCR reactor denitration of the side A spray ammonia self-regulation effect.
Fig. 7 be the utility model embodiment optimization after the SCR reactor denitration of the side B spray ammonia self-regulation effect.
Fig. 8 be the utility model embodiment optimization after SCR denitration reaction device outlet NOxConcentration set point+10 ranks of forward direction
Jump upset test figure.
Unit chimney entrance NO when Fig. 9 is the AGC-R mode of the utility model embodimentxConcentration self-regulation effect figure.
In Fig. 1: boiler economizer 1, SCR reactor 2, air preheater 3, SCR reactor inlet 4, No.1 ammonia-spraying grid
5,6, No. two ammonia-spraying grids 7, catalyst layer 8, SCR reactor outlet 9, regulating valve 10, flowmeters 11 of deflector.
Specific embodiment
The utility model is described in further detail with reference to the accompanying drawing and by embodiment, and following embodiment is pair
The explanation of the utility model and the utility model is not limited to following embodiment.
Embodiment.
Referring to Fig. 1, the device of the adjusting denitration spray ammonia flow of feedforward is added to include SCR based on cascade PID in the present embodiment
Reactor 2, electric control valve 10 and flowmeter 11 etc., the setting of SCR reactor 2 boiler economizer 1 and air preheater 3 it
Between；SCR reactor 2 includes SCR reactor inlet 4, No.1 ammonia-spraying grid 5, deflector 6, No. two ammonia-spraying grids 7, catalyst layers 8
With SCR reactor outlet 9；SCR reactor inlet 4 is adjacently positioned with boiler economizer 1, SCR reactor outlet 9 and air preheat
Device 3 is adjacently positioned；No.1 ammonia-spraying grid 5,6, No. two ammonia-spraying grids 7 of deflector and catalyst layer 8 along flue gas flow direction
It is sequentially arranged, No.1 ammonia-spraying grid 5 and SCR reactor inlet 4 is adjacently positioned, No. two ammonia-spraying grids 7 and the adjacent cloth of catalyst layer 8
It sets；Electric control valve 10 and flowmeter 11 are provided on ammonia main pipe road in SCR reactor 2, regulating valve 10 is for adjusting ammonia
The flow of gas, flowmeter 11 are used to measure the flow of ammonia.
In the present embodiment, catalyst layer 8 is plate armature, and catalyst layer 8 is provided with 4 layers, and every layer of catalyst layer 8 is homogeneous
Neighbour is disposed with a No.1 ammonia-spraying grid 5 or No. two ammonia-spraying grids 7.
Above-mentioned adds the working method for adjusting the device that ammonia flow is sprayed in denitration of feedforward as shown in Figure 2 based on cascade PID: main
The NO of pid loop PID1 adjusting SCR reactor outlet 9xConcentration, the output of main pid loop PID1 is after a correction function
Theory spray ammonia flow is modified, secondary pid loop PID2 adjusts ammonia supply flow, and the output of secondary pid loop PID2 adds
The sum of four feedforwards are applied to spray ammonia flow regulating valve 10 to adjust the size of ammonia spraying amount；Four feedforwards include that SCR reactor goes out
The NO of mouth 9xMeasured value reduces the NO of the function of definite value deviation, the function of unit load change rate, SCR reactor inlet 4xConcentration
The function of change rate and desulfurization export NOxThe function of concentration；Due to the inaccuracy of flue gas flow measurement, this working method is created
Property by main steam flow computational theory spray ammonia flow, as shown in formula (1):
In formula: Q is ammonia flow needed for 2 theory of unilateral side SCR reactor, kg/h；CinFor the NO of SCR reactor inlet 4xIt is dense
Degree, mg/m3；CoutsetFor the NO of SCR reactor outlet 9xConcentration set point, mg/m3；QAAnd QBRespectively boiler first side main steam
Flow and second side main steam flow, t/h；A is coefficient, according to designed under unit rated load flue gas flow, main steam flow,
NO2Molal weight and NH3Molal weight is calculated.
The NO of SCR reactor outlet 9xConcentration process values are used as main pid loop after lead-lag module Leadlag1
The process values of PID1, the NO of SCR reactor outlet 9xSetting value of the concentration set point as main pid loop PID1, main pid loop
PID1 uses positive interaction, proportional integration operation.
The output of main pid loop PID1 after correction function f1 (x) multiplied by theoretical ammonia spraying amount, i.e., to theoretical ammonia spraying amount into
Row amendment, correction factor range, that is, function f1 (x) output are as follows: a-b, a <b；Revised theory ammonia spraying amount is applied to adder
It on ∑ 1, is added with the manual amount of bias of operations staff, obtains actual needs ammonia spraying amount；Actual needs is sprayed into ammonia according to unit operating condition
Amount carries out marking the setting value after change is handled as secondary pid loop PID2 multiplied by coefficient B；Actually measured ammonia flow
Value carries out marking the process values after change is handled as secondary pid loop PID2 equally multiplied by coefficient B；Secondary pid loop PID2 is used
Reaction, proportional integration operation.
Conventional feed forward design is as follows:
The NO of one: SCR reactor outlet 9 of feedforwardxConcentration process values are anti-with SCR after lead-lag module Leadlag1
Answer the NO of device outlet 9xConcentration set point is subtracted each other, and is then scaled spray 10 opening size of ammonia regulating valve by function f2 (x), then pass through
Amplitude limit link Lmt1 is crossed, to ensure that role during adjusting spray 10 aperture of ammonia regulating valve of feedforward one is moderate；
Feedforward two: unit load is applied on adder ∑ 2 all the way after lead-lag module Leadlag2, is made all the way
On the output action to adder ∑ 2 for using lead-lag module Leadlag3, Leadlag3, the two is subtracted each other as unit load
Then change rate is scaled spray 10 opening size of ammonia regulating valve, using amplitude limit link Lmt2, with true after function f3 (x)
It is moderate to protect role during adjusting spray 10 aperture of ammonia regulating valve of feedforward two；By the way that unit is exchanged and observed with operations staff
Historical data finds the NO of SCR reactor inlet 4 in most casesxConcentration is reduced as unit load increases, with
Unit load reduce and increase.Therefore consider most situations, i.e. setting function f3 (x) slope is negative, as unit is negative
Lotus increases and reduces spray 10 aperture of ammonia regulating valve, increases spray 10 aperture of ammonia regulating valve as unit load reduces；
The NO of three: SCR reactor inlet 4 of feedforwardxConcentration process values are made all the way after lead-lag module Leadlag4
It uses on adder ∑ 3, is applied to the output action of lead-lag module Leadlag5, Leadlag5 all the way to adder ∑ 3,
The two subtracts each other the NO as SCR reactor inlet 4xThen change rate of concentration is scaled spray ammonia regulating valve after function f4 (x)
10 opening sizes are acted as using amplitude limit link Lmt3 with ensuring to feedover three during adjusting and spraying 10 aperture of ammonia regulating valve
With moderate；
Feedforward four: desulfurization exports NOxConcentration process values are applied to function f5 after lead-lag module Leadlag6
(x), spray 10 opening size of ammonia regulating valve is scaled after function f5 (x), using amplitude limit link Lmt4, to ensure feedforward four
Role is moderate during adjusting spray 10 aperture of ammonia regulating valve.
Unit is purged per will do it a CEMS every other hour, during purging, the NO of SCR reactor inlet 4xConcentration and
The NO of SCR reactor outlet 9xConcentration remains unchanged；Therefore, during purging, main pid loop PID1 is no longer adjusted,
Feedforward one and feedforward three remain unchanged, if having firing optimization, coal varitation, load variations or start and stop mill situation during this,
Easily cause the NO of SCR reactor outlet 9xThe NO of concentration and chimney entrancexConcentration over-standard；Therefore it during CEMS purging, allows de-
Sulphur exports NOxConcentration participates in adjusting；A handoff block T is provided in feedforward four, during CEMS is purged, desulfurization exports NOxConcentration
It participates in adjusting, after CEMS is purged, desulfurization exports NOxConcentration adjustment effect is reduced to zero.
The output of secondary pid loop PID2 is added on adder ∑ 4 jointly plus 4 feedforwards, using amplitude limit link
Lmt5, clipping size are determined according to unit actual condition and operations staff's experience are comprehensive；Spray ammonia is applied to after clipping to adjust
Valve 10 adjusts ammonia spraying amount size, controls the NO of SCR reactor outlet 9xConcentration and chimney entrance NOxConcentration.
Below by taking certain power plant 335MW unit as an example, the content of the utility model is described in detail.
The machine pool-size is 335MW, and boiler is the subcritical Natural Circulation drum boiler that Dongfang Boiler Factory manufactures and designs, model
For DG1000/170-I type, single drum, dry ash extraction, corner tangential firing, using low NO, selective catalytic reduction
(SCR) flue-gas denitration process controls NOxDischarge.Unit denitration control system is FOXBRO system.
SCR denitration ammonia-gas spraying device schematic diagram is as shown in Figure 1.
Equipment for denitrifying flue gas use high dirt type technique, be arranged between boiler economizer 1 and air preheater 3, flue gas from
Boiler economizer 1, which comes out, passes through SCR reactor 2, then arrives air preheater 3.Four layers of arrangement is flat in SCR reactor 2 urges
Agent layer 8, reducing agent are liquefied ammonia.Liquefied ammonia flash to ammonia with dilution wind mix after, by being arranged in 4 cigarette of SCR reactor inlet
No.1 ammonia-spraying grid 5 on road section is injected in SCR reactor 2, and under the effect of the catalyst, ammonia and nitrogen oxides occur
Reaction.Electric control valve 10 is provided on the ammonia main pipe road of SCR reactor 2, for adjusting ammonia flow, in ammonia main pipe
Road is equipped with flowmeter 11, measures the flow of ammonia.
Under the unit design conditions, the NO of SCR reactor inlet 4xConcentration is 450mg/m3, export NOxConcentration is less than
50mg/m3, denitration efficiency is not less than 88.9%.In SCR reactor 2, the main chemical reaction of generation is as follows:
4NO+4NH3+O2→4N2+6H2O
Denitration spray ammonia Automatic Control Strategy SAMA figure is as shown in Figure 3 before optimizing.It is " based on single that original spray ammonia, which automatically controls logic,
Pid loop adds feedforward " control mode, pid loop adjust SCR reactor outlet 9 NOxConcentration, feedforward include SCR reactor
The NO of outlet 9xThe NO of concentration process values and the departure function of setting value, SCR reactor inlet 4xChange rate of concentration and unit load
Function three parts, three feedforward and pid loop output phase superposition to spray ammonia regulating valve 10, adjust spray ammonia flow it is big
It is small.
Due to the delay that the response characteristic and CEMS of SCR denitrating flue gas measure, SCR denitration system has non-linear, big used
The characteristics of property.Under former control mode, spray ammonia self-regulation effect is poor, and fluctuation range is big, and especially liquefied ammonia supply pressure has
Under the operating condition of variation, unit fast lifting load or switching coal pulverizer, it is often necessary to which operations staff intervenes, carries out ammonia spraying amount manually
Adjustment.Before optimization, denitration spray ammonia self-regulation effect is as shown in Figure 4 and Figure 5, and the side A Benitration reactor exports NOxConcentration control
In ± 15 range of setting value, the side B Benitration reactor exports NOxConcentration controls in ± 20 range of setting value.In denitration facility
When CEMS is purged, the side A, the side B Benitration reactor export NOxConcentration controls in ± 25 range of setting value, and overshoot sometimes can be tighter
Weight.
Control strategy optimizes as follows:
Due to the inaccuracy of flue gas flow measurement, ammonia flow is sprayed by main steam flow computational theory in the present embodiment,
As shown in formula (1):
In formula: Q is ammonia flow needed for 2 theory of unilateral side SCR reactor, kg/h；CinFor the NO of SCR reactor inlet 4xIt is dense
Degree, mg/m3；CoutsetFor the NO of SCR reactor outlet 9xConcentration set point, mg/m3；QA、QBRespectively boiler first side main steam flow
Amount and second side main steam flow, t/h；A is coefficient, according to design flue gas flow, main steam flow, NO under unit rated load2
Molal weight, NH3Molal weight is calculated, a=0.0004 after calculating in this example.
As shown in Fig. 2, the NO of SCR reactor outlet 9xThe conduct after lead-lag module Leadlag1 of concentration process values
The process values of main pid loop PID1, the NO of SCR reactor outlet 9xSetting value of the concentration set point as main pid loop PID1,
Main pid loop PID1 uses positive interaction, proportional integration operation, and the proportional band of PID1 is set as 15, and the time of integration is set as 0.5min.
The output of main pid loop PID1 after correction function f1 (x) multiplied by theoretical ammonia spraying amount, i.e., to theoretical ammonia spraying amount into
Row amendment, correction function f1 (x) are provided that
| x | 0 | 50 | 100 |
| f1(x) | 0.6 | 1 | 1.7 |
The output area of correction function f1 (x) is 0.6-1.7.Revised theory ammonia spraying amount is applied to adder ∑ 1
On, it is added with the manual amount of bias of operations staff, obtains actual needs ammonia spraying amount.Ammonia spraying amount will be actually needed again according to unit operating condition
Multiplied by coefficient B, that is, carry out marking the setting value after change is handled as secondary pid loop PID2, coefficient B is set as 0.8 in the present embodiment.
Actually measured ammonia flow magnitude carries out marking the process after change is handled as secondary pid loop PID2 equally multiplied by coefficient B
Value.Secondary pid loop PID2 uses reaction, proportional integration operation, and the proportional band of PID2 is set as 230, and the time of integration is set as
1.2min。
Conventional feed forward design is as follows:
The NO of one: SCR reactor outlet 9 of feedforwardxConcentration process values are anti-with SCR after lead-lag module Leadlag1
Answer the NO of device outlet 9xConcentration set point is subtracted each other, and is then scaled spray 10 opening size of ammonia regulating valve, function by function f2 (x)
F2 (x) is provided that
| x | -120 | -2 | 2 | 120 |
| f2(x) | -95 | 0 | 0 | 95 |
Using amplitude limit link Lmt1, to ensure that role during adjusting spray 10 aperture of ammonia regulating valve of feedforward one is suitable
In.
Feedforward two: unit load is applied on adder ∑ 2 all the way after lead-lag module Leadlag2, is made all the way
On the output action to adder ∑ 2 for using lead-lag module Leadlag3, Leadlag3, the two is subtracted each other as unit load
Change rate, is then scaled spray 10 opening size of ammonia regulating valve after function f3 (x), and function f3 (x) is provided that
| x | -50 | -2 | 2 | 50 |
| f3(x) | 15 | 0 | 0 | -25 |
Using amplitude limit link Lmt2, to ensure that role during adjusting spray 10 aperture of ammonia regulating valve of feedforward two is suitable
In.By the way that unit historical data is exchanged and observed with operations staff, SCR denitration entrance NO in most cases is foundxIt is dense
Degree can be reduced as unit load increases, and be increased as unit load reduces.Therefore consider most situations, that is, be arranged
Function f3 (x) slope is negative, and reduces spray 10 aperture of ammonia regulating valve as unit load increases, increases as unit load reduces
Big spray 10 aperture of ammonia regulating valve.
The NO of three: SCR reactor inlet 4 of feedforwardxConcentration process values are made all the way after lead-lag module Leadlag4
It uses on adder ∑ 3, is applied to the output action of lead-lag module Leadlag5, Leadlag5 all the way to adder ∑ 3,
The two subtracts each other the NO as SCR reactor inlet 4xThen change rate of concentration is scaled spray ammonia regulating valve after function f4 (x)
10 opening sizes, function f4 (x) are provided that
| x | -50 | -3 | 3 | 50 | 100 |
| f4(x) | -20 | 0 | 0 | 20 | 40 |
Using amplitude limit link Lmt3, to ensure that role during adjusting spray 10 aperture of ammonia regulating valve of feedforward three is suitable
In.
Feedforward four: desulfurization exports NOxConcentration process values are applied to function f5 after lead-lag module Leadlag6
(x), spray 10 opening size of ammonia regulating valve is scaled after function f5 (x), function f5 (x) is provided that
| x | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 60 | 85 |
| f5(x) | -8 | -5 | -2.5 | 0 | 5 | 10 | 15 | 25 | 25 |
Using amplitude limit link Lmt4, to ensure that role during adjusting spray 10 aperture of ammonia regulating valve of feedforward four is suitable
In.
Unit purges (two sides A, B SCR reactor inlet 4, SCR reactor outlet per will do it a CEMS every other hour
9, CEMS purge simultaneously, and the time is 9 minutes), during purging, the NO of SCR reactor inlet 4xConcentration and SCR reactor outlet 9
NOxConcentration remains unchanged.Therefore, during purging, main pid loop PID1 is no longer adjusted, feedforward one and feedforward three
It remains unchanged, if there is situations such as firing optimization, coal varitation, load variations or start and stop are ground during this, easily causes SCR anti-
Answer the NO of device outlet 9xConcentration and chimney entrance NOxConcentration over-standard.Therefore during CEMS purging, desulfurization is allowed to export NOxConcentration ginseng
With adjusting.A handoff block T is provided in feedforward four, during CEMS is purged, desulfurization exports NOxConcentration participates in adjusting, CEMS
After purging, desulfurization exports NOxConcentration adjustment effect is reduced to zero.
The output of secondary pid loop PID2 is added on adder ∑ 4 jointly plus 4 feedforwards, using amplitude limit link
Lmt5, clipping size are determined according to unit actual condition and operations staff's experience are comprehensive.Spray ammonia is applied to after clipping to adjust
Valve 10 adjusts ammonia spraying amount size, controls the NO of SCR reactor outlet 9xConcentration and chimney entrance NOxConcentration.
After carrying out denitration spray ammonia control optimization according to this programme, denitration spray ammonia automatic adjustment is stablized, NOxStably reaching standard row
It puts.After optimization, unit is in AGC-O mode, the NO of the side A SCR reactor outlet 9xConcentration can be controlled in ± 10 range of setting value
It is interior, the NO of the side B SCR reactor outlet 9xConcentration is can be controlled in ± 15 range of setting value, and after optimization, ammonia automatic adjustment is sprayed in denitration
Effect is as shown in Figure 6 and Figure 7.Chimney entrance NOxConcentration is smoothly controlled in minimum discharge required value 50mg/m3Hereinafter, usually existing
28mg/m3—46mg/m3Fluctuation in range, spray ammonia, which automatically controls, to be stablized.
After optimization, to the NO of SCR reactor outlet 9xConcentration set point has carried out the step disturbance test of forward direction+10, adjusts
Effect is saved as shown in figure 8, parameters change steady, the NO of SCR reactor outlet 9xConcentration can be rapidly achieved setting value.
After optimization, unit is in AGC-R mode, the NO of unit load and SCR reactor inlet 4xConcentration changes violent
In the case of, utility model device can automatically adjust the NO that ammonia spraying amount tracks SCR reactor inlet 4 in timexThe variation of concentration,
Chimney entrance NOxConcentration regulating effect is as shown in Figure 9.From fig. 9, it can be seen that most of in tri- hours of 02:10-05:10
Time chimney entrance NOxConcentration is in 30mg/m3—46mg/m3Between fluctuate, meet the requirement of unit minimum discharge.
Although the utility model is disclosed as above with embodiment, its protection scope being not intended to limit the utility model,
Any technical staff for being familiar with this technology, it is made in the conception and scope for not departing from the utility model to change and retouch,
It all should belong to the protection range of the utility model.
Claims (2)
1. a kind of device for adjusting denitration spray ammonia flow for adding feedforward based on cascade PID, including SCR reactor, the SCR reaction
Device is arranged between boiler economizer and air preheater；It is characterized in that, further including electric control valve and flowmeter；It is described
SCR reactor includes SCR reactor inlet, No.1 ammonia-spraying grid, deflector, No. two ammonia-spraying grids, catalyst layer and SCR reaction
Device outlet；The SCR reactor inlet is adjacently positioned with boiler economizer, the SCR reactor outlet and air preheater phase
Neighbour's arrangement；The No.1 ammonia-spraying grid, deflector, No. two ammonia-spraying grids and catalyst layer along flue gas flow direction successively cloth
It sets, the No.1 ammonia-spraying grid is adjacently positioned with SCR reactor inlet, No. two ammonia-spraying grids and the adjacent cloth of catalyst layer
It sets；Electric control valve and flowmeter are provided on ammonia main pipe road in the SCR reactor, the regulating valve is for adjusting ammonia
The flow of gas, the flowmeter are used to measure the flow of ammonia.
2. the device according to claim 1 that adjust denitration spray ammonia flow for being added feedforward based on cascade PID, feature are existed
In the catalyst layer is plate armature, and the catalyst layer is provided with 4 layers, and every layer of catalyst layer is adjacent to be disposed with one
A ammonia-spraying grid.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109092035A (en) * | 2018-08-31 | 2018-12-28 | 华电电力科学研究院有限公司 | A kind of device and its working method for adjusting denitration spray ammonia flow adding feedforward based on cascade PID |
| CN110501901A (en) * | 2019-07-08 | 2019-11-26 | 华能南京金陵发电有限公司 | The SCR spray ammonia required based on the accurate denitration of full load adjusts the method optimized |
| CN110618706A (en) * | 2019-09-27 | 2019-12-27 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Multistage intelligent denitration online optimization control system based on data driving |
| CN111781823A (en) * | 2020-07-10 | 2020-10-16 | 国网湖南省电力有限公司 | A Dynamic Feedforward Setting Method for Ammonia Injection Deviation Suppression |
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2018
- 2018-08-31 CN CN201821424687.1U patent/CN209020167U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109092035A (en) * | 2018-08-31 | 2018-12-28 | 华电电力科学研究院有限公司 | A kind of device and its working method for adjusting denitration spray ammonia flow adding feedforward based on cascade PID |
| CN110501901A (en) * | 2019-07-08 | 2019-11-26 | 华能南京金陵发电有限公司 | The SCR spray ammonia required based on the accurate denitration of full load adjusts the method optimized |
| CN110501901B (en) * | 2019-07-08 | 2022-05-10 | 华能南京金陵发电有限公司 | SCR ammonia injection regulation optimization method based on full-load accurate denitration requirement |
| CN110618706A (en) * | 2019-09-27 | 2019-12-27 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Multistage intelligent denitration online optimization control system based on data driving |
| CN110618706B (en) * | 2019-09-27 | 2023-05-12 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Multistage intelligent denitration on-line optimization control system based on data driving |
| CN111781823A (en) * | 2020-07-10 | 2020-10-16 | 国网湖南省电力有限公司 | A Dynamic Feedforward Setting Method for Ammonia Injection Deviation Suppression |
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