CN106268239A - The control method that the integration of thermal power plant's denitration control system separates - Google Patents
The control method that the integration of thermal power plant's denitration control system separates Download PDFInfo
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- 230000010354 integration Effects 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 30
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 94
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 46
- 239000007921 spray Substances 0.000 claims abstract description 31
- 230000008859 change Effects 0.000 claims abstract description 6
- 230000003321 amplification Effects 0.000 claims description 39
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 39
- 238000004364 calculation method Methods 0.000 claims description 34
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 12
- 239000003546 flue gas Substances 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 230000005540 biological transmission Effects 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 230000008901 benefit Effects 0.000 claims description 8
- 238000010926 purge Methods 0.000 claims description 8
- 239000000446 fuel Substances 0.000 claims description 7
- 238000005507 spraying Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000005259 measurement Methods 0.000 claims description 2
- 238000000465 moulding Methods 0.000 claims 1
- 239000003245 coal Substances 0.000 abstract description 10
- 229920006395 saturated elastomer Polymers 0.000 abstract description 7
- 230000007423 decrease Effects 0.000 abstract description 3
- 230000001276 controlling effect Effects 0.000 description 7
- 230000009471 action Effects 0.000 description 5
- 230000000875 corresponding effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 241001347978 Major minor Species 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- -1 exists with NO form Chemical compound 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000012886 linear function Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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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
- B01D53/76—Gas phase processes, e.g. by using aerosols
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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
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
- G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
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- Oil, Petroleum & Natural Gas (AREA)
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- Dispersion Chemistry (AREA)
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Abstract
The present invention relates to the control method that the integration of a kind of thermal power plant denitration control system separates.The method comprises the steps: that S1. minimum denitration efficiency controls；S2. integration separates and controls；S3. spray ammonia flow set point correct；S4. the jet flow amount feedforward.The present invention uses the method that integration separates, it is possible to effectively control spray ammonia flow and the discharge of thermal power plant NOx, it is possible to prevent integration saturated, and reduces station service power consumption rate, improves unit generation efficiency；The present invention uses cascade loop control simultaneously, spray ammonia flow set point correct loop and ammonia amount feed forward control loop decrease the change of coal in practical operation situation, the randomness of burning, etc. many uncertainties and perturbation on controlling the impact that produces.
Description
Technical field
The present invention relates to the control method of a kind of thermal power plant denitration, the integration of a kind of thermal power plant denitration control system
The control method separated.
Background technology
Starting from 2006, China's coal unit the most progressively puts into operation denitrating system, and selective catalysis reducing process (SCR) denitration is
Group of motors Application comparison a kind of flue-gas denitrification technology widely the most both at home and abroad.Ammonia is first mixed with the air of 20 times of oneself volumes
Close, then the flue gas with 320-400 DEG C mixes, and then completes denitration reaction by catalyst, according to denitration principle by spray ammonia stream
Amount controls SCR exit NOx concentration and does not exceeds standard, and controls ammonia and escape and command troops to exceed standard, and therefore spray ammonia automatic control system is adjusted
Joint quality is the best, and denitration effect is the best, and ammonia escapement ratio is the fewest.
Thus, for denitrating system, it is badly in need of a set of science, the integration partition method of practical denitration control system, is used for controlling
System spray ammonia flow, effectively controls the discharge of thermal power plant NOx, prevents integration saturated, reduces station service power consumption rate and improves unit generation efficiency.
Summary of the invention
The technical problem to be solved is to provide a kind of effective control and sprays ammonia flow and the fire of thermal power plant's NOx emission
The control method that the integration of power plant's denitration control system separates.
It is as follows that the present invention solves the technical scheme that above-mentioned technical problem used:
The control method that the integration of thermal power plant's denitration control system separates, comprises the steps:
S1. minimum denitration efficiency controls: denitration efficiency setting value inputs to the first deviation computing module, by the first deviation
The output of computing module and the measured value of entrance NOx input to the first multiplication computing module respectively, by the first multiplication computing module
Output input to the first inertial delay module, the output valve of the first inertial delay module is the setting value of the maximum NOx of outlet；
S2. integration separates and controls: the measured value that input is outlet NOx of the second inertial delay module, and exports to the 3rd
Inertial delay module, the 3rd inertial delay module exports to the 4th inertial delay module, and the 4th inertial delay module output is to the
One additional calculation module, the input of the first additional calculation module also includes the measured value exporting NOx, and exports to the first coefficient and put
Big module, the input of the second additional calculation module is output and the measured value of outlet NOx of the first coefficient amplification module, and second
The output valve of additional calculation module is revised outlet NOx measured value, and little value selects the setting that input is outlet NOx of module
Value and the maximum NOx setting value of outlet, the input of the second deviation computing module is that little value selects the output of module and revised NOx
Measured value, and output, to selecting module and the second coefficient amplification module, selects module to export to integration module, the 3rd addition respectively
Output that the input of computing module is integration module and the output of the second coefficient amplification module, and the 3rd addition computing module is defeated
Go out the spray ammonia corrected value that value is external loop；
S3. spray ammonia flow set point correct: the input of the 3rd deviation computing module is entrance NOx measured value and outlet NOx
Measured value, the input of the 4th additional calculation module is the 3rd addition computing module output and the output of the 3rd deviation computing module, the
The input of square law computing module is output and the output of function performance module of the 4th additional calculation module, function performance module
Input be the measured value of total fuel quantity, be output as theoretical ammonia flow value of calculation, the input of the 3rd coefficient amplification module is the
The output of square law module, the 3rd coefficient amplification module is output as the spray ammonia flow setting value of inner looping；Wherein, function performance
Module for being converted to the flue gas flow of correspondence by fuel quantity measured value；
S4. the jet flow amount feedforward: the input of the 5th inertial delay module is entrance NOx measured value, fifth adding calculates
The input of module is output and the entrance NOx measured value of the 5th inertial delay module, and fifth adding computing module exports to the 4th
Coefficient amplification module；The input of the 6th inertial delay module is oxygen content, and the input of the 6th additional calculation module is the 6th inertia
The output of Postponement module and oxygen content, and export to the 5th coefficient amplification module；The input of control module is that the 4th coefficient amplifies
The output of module, the output of the 5th coefficient amplification module, the output of the 3rd coefficient amplification module and the 7th inertial delay module
Output, control module is output as spraying ammonia flow control signal.
The present invention uses the method that integration separates, it is possible to effectively control spray ammonia flow and the discharge of thermal power plant NOx, it is possible to anti-
Only integration is saturated, and reduces station service power consumption rate, improves unit generation efficiency.
As preferably, in step S1, denitration efficiency setting value is 100%.Have an advantage in that, improve denitration efficiency and denitration
Effect.
As preferably, in step S2, selecting at module, when outlet instruments purging signal comes, selecting the defeated of module
Going out value is 0, when purging signal and not occurring, selects the output valve that output valve is the second deviation computing module of module.
As preferably, in step S3, the 3rd deviation computing module is output as being actually needed the NOx being neutralized.
As preferably, the first to the 7th inertial delay module is respectively used to make signal conversion slowly, and has certain time
Time delay, transmission function is:Wherein, G (s) is to describe linear system for transmission function
The basic mathematical instrument of dynamic characteristic, Y (s) is the laplace transform of output, and X (s) is the laplace transform of input quantity, k
For the proportionality coefficient of inertial element, T1, T2 are the time constant of property link, and S is complex frequency domain.Have an advantage in that, it is possible to improve big
The dynamic characteristic of inertia control object, accelerates system response time.
As preferably, the first to the 6th additional calculation module is respectively used to calculate the sum of two input values, computing formula
For A=input value 1* input value 1 gain+input value 2* input value 2 gain；First and second multiplication computing module is used for calculating two
Amassing of individual input value, computing formula is A=input value 1* input value 2；The scope of input value 1 gain and input value 2 gain is respectively
Be 0 to 2.Having an advantage in that, General System function coefficient is 1, and peer machine function coefficient can produce deviation, it is contemplated that logic
Concordance, arranges gain in additional calculation module.
As preferably, the first to the 5th coefficient amplification module is respectively used to zoom in and out input value according to gain, calculates
Formula is A=input value * input value gain；Input value gain is in the range of 0 to 2.Have an advantage in that,
As preferably, control module is used for providing proportional plus integral plus derivative controller function, and its transmission function is:Wherein, G (S) is that description linear system is dynamic for transmission function
The basic mathematical instrument of characteristic, U (S) is the laplace transform of output, and E (S) is the laplace transform of input quantity, and Kp is
Proportionality coefficient in control module, Ti is the time of integration in control module, and Td is the derivative time in control module, and S is multiple
Frequency domain.Have an advantage in that so that whole control process is more controllable, improve denitration efficiency and generating set efficiency.
As preferably, integration module is for calculating the integration of input value；First to the 3rd deviation computing module is used for calculating
The arithmetical difference of two input values, computing formula is A=input value 1-input value 2；Little value selects module for two to input
Value carries out little selection, and when input value 1 is more than input value 2, module is output as input value 2；When input value 1 is less than input value 2,
Module is output as input value 1.
The present invention compared with the existing technology has the following advantages and effect:
1, owing to the invention mainly comprises four partial contents, minimum denitration efficiency controls, integration separates control, spray ammonia flow
Set point correct and the ammonia spraying amount feedforward, it is possible to effectively prevent controlling contour integration saturated, effectively control fired power generating unit outlet
NOx emission, reduces the escaping of ammonia rate, reduces station service power consumption rate, improves unit generation efficiency.
2, cascade loop control, spray ammonia flow set point correct loop and the ammonia amount feedforward is used to return due to the present invention
Road decrease the change of coal in practical operation situation, the randomness of burning, etc. many uncertainties and perturbation to controlling to produce
Raw impact.
3, control owing to the present invention uses integration to separate, when instrument is in maintenance process, enter the deviation of integrating function block
Value switches to 0, and integral action stops, and prevents integral action from developing to saturated direction, is conducive to controlling loop and obtains more preferable tune
Joint quality
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to
Other accompanying drawing is obtained according to these accompanying drawings.
The integration separation method of Tu1Shi thermal power plant of the present invention denitration control system realizes logic chart.
Label declaration:
1, minimum denitration efficiency control loop 2, integration separate control loops 3, spray ammonia flow set point correct loop 4,
The 102, first deviation computing module the 103, first multiplication computing module the 104, first inertial delay of jet flow amount feed forward control loop
Module 105, little value select module the 106, second deviation computing module the 107, second additional calculation module the 108, second inertia
Postponement module the 109, the 3rd inertial delay module the 110, the 4th inertial delay module the 111, first additional calculation module 112,
First coefficient amplification module 113, selection module 116, integration module the 117, the 3rd addition computing module the 118, second coefficient
Amplification module the 119, the 3rd deviation computing module the 120, the 4th additional calculation module the 121, the 5th inertial delay module 122,
Fifth adding computing module the 123, the 4th coefficient amplification module the 124, second multiplication computing module 125, function performance module
126, the 3rd coefficient amplification module the 127, the 7th inertial delay module the 128, the 6th inertial delay module the 129, the 6th addition meter
Calculate module the 130, the 5th coefficient amplification module 131, control module
Detailed description of the invention
Below in conjunction with embodiment, the present invention is described in further detail, following example be explanation of the invention and
The invention is not limited in following example.
Embodiment 1:
As it is shown in figure 1, the control method that the integration of thermal power plant's denitration control system of the present embodiment separates, main following four
Part:
Part I: minimum denitration efficiency controls loop 1 part.By denitration efficiency setting value 100% (i.e. denitration efficiency
Maximum 100%) input to the first deviation computing module 102, by the output of the first deviation computing module 102 and entrance NOx
The first multiplication computing module 103 is given in measured value input respectively, and the output of the first multiplication computing module 103 is inputed to the first inertia
Postponement module 104, the output valve of this first inertial delay module 104 is the setting value of the maximum NOx of outlet.
Part II: integration separate control loops 2 part.The survey that input is outlet NOx of the second inertial delay module 108
Value, and export to the 3rd inertial delay module 109, the 3rd inertial delay module 109 exports to the 4th inertial delay module
110, the 4th inertial delay module 110 exports to the first additional calculation module 111, and the input of the first additional calculation module 111 is also
Including the measured value of outlet NOx, and exporting to the first coefficient amplification module 112, the input of the second additional calculation module 107 is the
The output of one coefficient amplification module 112 and the measured value of outlet NOx, and the output valve of the second additional calculation module 107 is for revising
After outlet NOx measured value, little value selects setting value and the maximum NOx setting value of outlet that the input of module 105 is outlet NOx,
The input of the second deviation computing module 106 is that little value selects the output of module 105 and revised NOx measured value, and the most defeated
Go out to selecting module 113 and the second coefficient amplification module 118, select module 113 to export to integration module 116, the 3rd addition meter
What the input calculating module 117 was integration module 116 exports and the output of the second coefficient amplification module 118, and the 3rd additional calculation
The output valve of module 117 is the spray ammonia corrected value of external loop.
Selecting at module 113, when purging signal and not occurring, the output valve selecting module 113 is that the second deviation calculates
The output valve of module 106；When outlet instruments purging signal comes, the output valve selecting module 113 is 0, and integral action stops,
Prevent integral action from developing to saturated direction.
Above-mentioned revised NOx measured value is by second additional calculation module the 107, second to the 4th inertial delay mould
The corrective loop that block 108-110, the first additional calculation module 111 and coefficient amplification module 112 are formed obtains, and uses the most stagnant
The corrective loop of post-compensation method, has the feature of fast response time, have modified entrance PID (operational loop of next link) fortune
The outlet NOx measured value calculated, improves the dynamic characteristic of big inertia control object.
Part III: spray ammonia flow set point correct loop 3 part.The input of the 3rd deviation computing module 119 is entrance
NOx measured value and outlet NOx measured value, the input of the 4th additional calculation module 120 be the 3rd addition computing module 117 output and
3rd deviation computing module 119 exports, the output that input is the 4th additional calculation module 120 of the second multiplication computing module 124
With the output of function performance module 125, the measured value that input is total fuel quantity of function performance module 125, function performance module
125 are output as theoretical ammonia flow value of calculation, the output that input is the second multiplier module of the 3rd coefficient amplification module 126,
3rd coefficient amplification module 126 is output as the spray ammonia flow setting value of inner looping.Wherein, function performance module 125 is for inciting somebody to action
Fuel quantity measured value is converted to the flue gas flow of correspondence.3rd deviation computing module 119 is output as being actually needed and is neutralized
NOx。
The effect of above-mentioned function performance module 125 is the flue gas flow that fuel quantity measured value is converted to correspondence, function
Functional module 125 algorithm can generate piecewise linear function.
Part IV: jet flow amount feed forward control loop 4 part.The input of the 5th inertial delay module 121 is that entrance NOx surveys
Value, the input of fifth adding computing module 122 is output and the entrance NOx measured value of the 5th inertial delay module 121, the 5th
Additional calculation module 122 exports to the 4th coefficient amplification module 123；The input of the 6th inertial delay module 128 is oxygen content, the
The output that input is the 6th inertial delay module 128 of six additional calculation modules 129 and oxygen content, and export to the 5th coefficient and put
Big module 130；The input of control module 131 is the output of the 4th coefficient amplification module 123, the 5th coefficient amplification module 130
Output, the output of the 3rd coefficient amplification module 126 and the output of the 7th inertial delay module 127, control module 131 is output as
Spray ammonia flow control signal.
First to the 7th inertial delay module is respectively used to make input signal after inertial delay module, makes signal convert
Slowly, and having the time delay of certain time, transmission function is:, wherein, G (s) is to describe linear system dynamic characteristic for transmission function
Basic mathematical instrument, Y (s) is the laplace transform of output, and X (s) is the laplace transform of input quantity, and k is inertia rings
The proportionality coefficient of joint, T1, T2 are the time constant of property link, and S is complex frequency domain.
In above-mentioned integration separate control loops 2 part, because being object with big inertia, an inertial delay module delays rings
Should be slow not, need three inertial delay links to act on simultaneously, make the signal intensity of input inertial delay module produce certain
Delay, thus improve the dynamic characteristic of big inertia control object.
First to the 6th additional calculation module 129 is respectively used to calculate the sum of two input values, and computing formula is that A=is defeated
Enter to be worth 1* input value 1 gain+input value 2* input value 2 gain；First and second multiplication computing module 124 is defeated for calculating two
Entering the long-pending of value, computing formula is A=input value 1* input value 2；The scope of input value 1 gain and input value 2 gain be respectively 0 to
2。
First to the 5th coefficient amplification module 130 is respectively used to zoom in and out input value according to gain, and computing formula is A
The * input value gain of=input value；Input value gain is in the range of 0 to 2.
Control module 131 is used for providing proportional plus integral plus derivative controller function, and its transmission function is: wherein, G (S) is for passing
Delivery function is the basic mathematical instrument describing linear system dynamic characteristic, and U (S) is the laplace transform of output, and E (S) is
The laplace transform of input quantity, Kp is the proportionality coefficient in control module 131, and Ti is the time of integration in control module 131,
Td is the derivative time in control module 131, and S is complex frequency domain.
Integration module 116 is for calculating the integration of input value.
First to the 3rd deviation computing module is for calculating the arithmetical difference of two input values, and computing formula is A=input value
1-input value 2.
Little value selects module 105 two values being used for inputting to carry out little selection, when input value 1 is more than input value 2, and mould
Block is output as input value 2；When input value 1 is less than input value 2, module is output as input value 1.
The principle of the present invention is as follows:
Owing to the reaction of NOx Yu NH3 is slower process, in order to improve the regulating effect of control system, need denitration machine
Reason designs control system.In flue gas, NOx mainly exists with NO form, and the spray that can obtain being correlated with is according to quantity such as following formula:
Wherein, QLFlow, units/kg/h is filled for theory spray ammonia.QgFor flue gas flow rate, unit Nm3/h。[NOx]inFor denitration system
System inlet flue gas NOx content, unit mg/Nm3。[NOx]outFor denitration outlet smoke NOx content, unit mg/Nm3。17/46
It is NH3Ratio with the molecular weight of NOx.
If above flue gas flow measurement point is not installed or its corresponding measuring point error is relatively big, coal weighing can be passed through
Obtain, then above formula can be changed into:
Wherein, QcFor actual Coal-fired capacity, unit t/h.Corresponding function f (Qc) boiler design description can be passed through or adopt
It is calculated by formula below:
f(Qc)=1000*Vgy*Qc
Wherein, VgyFor the dry flue gas flow produced by every kg coal that burns, unit Nm3/kg.Corresponding computing formula is as follows:
Vgy=0.01866* (Car+0.375Sar)+(0.79V°+0.008*Nar)+(α-1)V°
Wherein, Car、Sar、NarIt is respectively the composition quantity such as the carbon of As-received, sulfur, nitrogen, relevant with the coal of burning, single
Position %.α is excess air coefficient, typically takes the constant between 1.1-1.4.V ° is the theoretical air requirement needed for often burning 1kg coal,
Unit Nm3/kg.Corresponding computing formula is as follows:
V °=0.0889* (Car+0.375Sar)+0.2643Har-0.0333Oar
Wherein, Har、OarIt is respectively the composition quantity such as the hydrogen of As-received, oxygen, relevant with the coal of burning, unit %.
Iff the ammonia spraying amount by above-mentioned theory calculating gained, can enter as the ammonia spraying amount setting value in control loop
Enter single loop PID to control, in order to regulate spray ammonia flow, finally control the discharge of NOx.This control program does not consider actual fortune
The change of coal in market condition, the randomness of burning, etc. many uncertainties and perturbation, necessarily cannot realize real closed loop
Control.Therefore, the present invention proposes outlet NOx introducing another one PID is carried out closed-loop corrected spray ammonia flow loop.Thus need to adopt
With corresponding serials control loop, control logic chart such as Fig. 1.
Being made up of as it is shown in figure 1, control loop major-minor PID, external loop is in order to control outlet NOx at setting value environs
Fluctuation；Inner looping regulates valve in order to control spray ammonia flow by spray ammonia；Wherein minimum denitration efficiency control loop 1 limits outlet
The maximum of NOx setting value, it is ensured that the efficiency in out of stock control loop.The reason calculated in spray ammonia flow set point correct loop 3
Opinion spray ammonia flow superposes the spray ammonia flow setting value generating inner looping with the spray ammonia corrected value of external loop.And theory ammonia flow
Calculating is to be obtained via function performance module 125 by burning coal amount.
Often enter maintenance, purging duty owing to measuring the instrument of smoke components, and need to blow every 2 hours probes
Sweeping once, each persistent period is 7-10 minute.During actual engineering design control system, it is necessary to consider under this situation
The integration saturated phenomenon brought.
As it is shown in figure 1, in order to prevent in meter probe purge, the numerical value of NOx constant causing occurs PID entrance for a long time
Deviation exists, and have employed the method that integration separates in controlling loop.Integration separate control loops 2 shown in Fig. 1 realizes,
This design is conducive to controlling loop and obtains more preferable regulation quality, decreases amount of ammonia slip to a certain extent.It addition,
In jet flow amount feed forward control loop 4, have employed lead-lag compensation tache and introduce system with paralleling model, big mainly for improving
The dynamic characteristic of inertia control object.Furthermore, it is contemplated that the growing amount of NOx is relevant with the oxygen content in flue gas, controlling loop
In also oxygen amount is introduced to control system as feedforward, the NOx brought to the advanced portion disturbances eliminated in combustion process
Change.
Furthermore, it is necessary to explanation, the specific embodiment described in this specification, the shape of its parts and components, it is named
Titles etc. can be different.All equivalences done according to structure, feature and the principle described in inventional idea of the present invention or simple change, all wrap
Include in the protection domain of patent of the present invention.Described can be embodied as by those skilled in the art
Example is made various amendment or supplements or use similar mode to substitute, without departing from the structure of the present invention or surmount this
Scope as defined in the claims, all should belong to protection scope of the present invention.
Claims (9)
1. the control method that the integration of thermal power plant's denitration control system separates, is characterized in that: comprise the steps:
S1. minimum denitration efficiency controls: denitration efficiency setting value inputs to the first deviation computing module, the first deviation is calculated
The output of module and the measured value of entrance NOx input to the first multiplication computing module respectively, defeated by the first multiplication computing module
Going out to input to the first inertial delay module, the output valve of described first inertial delay module is the setting value of the maximum NOx of outlet；
S2. integration separates and controls: the measured value that input is outlet NOx of the second inertial delay module, and exports to the 3rd inertia
Postponement module, the 3rd inertial delay module exports to the 4th inertial delay module, and the 4th inertial delay module output adds to first
Method computing module, the input of the first additional calculation module also includes the measured value exporting NOx, and exports to the first coefficient amplification mould
Block, the input of the second additional calculation module is output and the measured value of outlet NOx of the first coefficient amplification module, and the second addition
The output valve of computing module is revised outlet NOx measured value, little value select module input for outlet NOx setting value and
The maximum NOx setting value of outlet, the input of the second deviation computing module is that little value selects the output of module and revised NOx to measure
Value, and output, to selecting module and the second coefficient amplification module, selects module to export to integration module, the 3rd additional calculation respectively
What the input of module was integration module exports and the output of the second coefficient amplification module, and the output valve of the 3rd addition computing module
Spray ammonia corrected value for external loop；
S3. spray ammonia flow set point correct: the input of the 3rd deviation computing module is entrance NOx measured value and outlet NOx measurement
Value, the input of the 4th additional calculation module is the 3rd addition computing module output and the output of the 3rd deviation computing module, and second takes advantage of
The input of method computing module is output and the output of function performance module of the 4th additional calculation module, function performance module defeated
Entering the measured value for total fuel quantity, be output as theoretical ammonia flow value of calculation, the input of the 3rd coefficient amplification module is second to take advantage of
The output of method module, the 3rd coefficient amplification module is output as the spray ammonia flow setting value of inner looping；Wherein, described function performance
Module for being converted to the flue gas flow of correspondence by fuel quantity measured value；
S4. the jet flow amount feedforward: the input of the 5th inertial delay module is entrance NOx measured value, fifth adding computing module
The output that input is the 5th inertial delay module and entrance NOx measured value, fifth adding computing module export to the 4th coefficient
Amplification module；The input of the 6th inertial delay module is oxygen content, and the input of the 6th additional calculation module is the 6th inertial delay
The output of module and oxygen content, and export to the 5th coefficient amplification module；The input of control module is the 4th coefficient amplification module
Output, the output of the 5th coefficient amplification module, the output of the 3rd coefficient amplification module and the output of the 7th inertial delay module,
Control module is output as spraying ammonia flow control signal.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
Step S1 in, denitration efficiency setting value is 100%.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
Step S2 in, selecting at module, when outlet instruments purging signal comes, the output valve selecting module is 0, when purging letter
When number not occurring, select the output valve that output valve is the second deviation computing module of module.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
Step S3 in, the 3rd deviation computing module is output as being actually needed the NOx being neutralized.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
The first to the 7th inertial delay module be respectively used to make signal conversion slowly, and have the time delay of certain time, transmission function to be:Wherein, G (s) is to transmit the basic number that function is description linear system dynamic characteristic
Instrument, Y (s) is the laplace transform of output, and X (s) is the laplace transform of input quantity, and k is the ratio of inertial element
Coefficient, T1, T2 are the time constant of property link, and S is complex frequency domain.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
The first to the 6th additional calculation module be respectively used to calculate the sum of two input values, computing formula is that A=input value 1* is defeated
Enter value 1 gain+input value 2* input value 2 gain；First and second multiplication computing module is for calculating the long-pending of two input values, meter
Calculating formula is A=input value 1* input value 2；The scope of input value 1 gain and input value 2 gain is respectively 0 to 2.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
The first to the 5th coefficient amplification module be respectively used to zoom in and out input value according to gain, computing formula is A=input value *
Input value gain；Input value gain is in the range of 0 to 2.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described control
Molding block is used for providing proportional plus integral plus derivative controller function, and its transmission function is:
Wherein, G (S) is to transmit the basic mathematical instrument that function is description linear system dynamic characteristic, and U (S) is the La Pula of output
This change, E (S) is the laplace transform of input quantity, and Kp is the proportionality coefficient in control module, and Ti is amassing in control module
Between timesharing, Td is the derivative time in control module, and S is complex frequency domain.
The control method that the integration of thermal power plant the most according to claim 1 denitration control system separates, is characterized in that: described
Integration module for calculating the integration of input value；First to the 3rd deviation computing module is for calculating the arithmetic of two input values
Difference, computing formula is A=input value 1-input value 2；Little value selects module for two values of input are carried out little selection, when defeated
When entering value 1 more than input value 2, module is output as input value 2；When input value 1 is less than input value 2, module is output as input value
1。
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