CN105892504B - The control method and control system of a kind of thermal power plant's denitration for ammonia automatic loop - Google Patents
The control method and control system of a kind of thermal power plant's denitration for ammonia automatic loop Download PDFInfo
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Abstract
The invention discloses a kind of thermal power plant's denitrations for the control method and control system of ammonia automatic loop, is made of main control loop and auxiliary control circuit for ammonia automatic loop, the main control loop takes the outlet NO of SCR reactorsxConcentration is adjusted as process values, and the auxiliary control circuit includes multiple single control circuits, and each single control circuit, which takes, to be adjusted for ammonia flow as process values.Beneficial effects of the present invention are：By multiple functional relations, by boiler load, entrance NOxConcentration, outlet NOxInfluence of the disturbance to automatic control loop caused by the Parameters variations such as concentration is eliminated or is preferably minimized, it can make, for ammonia automatic loop early response, quickly to adjust, eliminate the influence of disturbed belt, achieve the purpose that accurately control.
Description
Technical field
The present invention relates to denitrations for ammonia technical field, in particular to a kind of thermal power plant's denitration for ammonia automatic loop
Control method and control system.
Background technology
With China environmental protection law, rule and standard it is increasingly stringent, gas denitrifying technology is widely used to absolutely
Most of Coal-fired groups.The NO generated for burningxControl method mainly has control and burning in the preceding control of burning, burning
After control 3 classes.Control is exactly to convert bunker coal to low nitrogen fuel, but its is difficult before burning, and cost is very high, engineer application
Seldom；Control refers to improving combustion system and production technology in burning, using low NOxCombustion technology reduces NO in stovexProduction quantity,
This method expense is relatively low, but due to the limitation of low-NO_x combustion technology in stove so that NOxControl effect is unsatisfactory；After burning
Control refers in flue tail De-NO_x, by the NO in flue gasxIt is changed into harmless N2Or useful fertilizer, because of its tool
Have the advantages that technology maturation, denitration efficiency are high, reliable for operation, is current NO most widely used in the worldxControl technology.
In the fired power generating unit in China, there is the SCR of control mode after 92% or more denitrification apparatus use burning
(Selective Catalytic Reduction, selective catalytic reduction) denitrating technique, the technology are by Ammonia reducing agent
Spray into flue gas in, under the effect of the catalyst selectively with NOxReduction reaction is carried out, by the NO in flue gasxIt is converted into N2With
H2O。
Common denitrification reducing agent has 3 kinds of liquefied ammonia, ammonium hydroxide and urea.The investment of liquefied ammonia, transport and cost of use are minimum, but
Liquefied ammonia belongs to dangerous material, it is necessary to have stringent safety assurance and fire prevention measure, transport and storage to be related to local statues and labor
Dynamic sanitary standard；Ammonium hydroxide transportation volume is huge, transport and carrying cost highest；Urea is a kind of safe graininess agricultural fertilizer
Material, no transport and storage problem, but ammonia system processed is complicated, and initial investment is larger.
Denitrating system in the process of running, if reducing agent penetrating is very few, can lead to NOxDischarge exceeded, electricity power enterprise general
Face the environmental protection punishment of great number；If reducing agent sprays into excessively, the waste of reducing agent is not only resulted in, increases operating cost, and
And the escapement ratio of ammonia is also will increase, and then greatly increase the risk of air preheater blocking.Therefore, thermal power plant is ensuring NOx
While emission compliance, also to enhance denitrating system reliability of operation, continuity and economy.Wherein, denitration is accurately controlled
The reducing agent straying quatity (hereinafter referred to as ammonia amount) of system becomes the key for avoiding discharge beyond standards, effectively reducing operating cost.
From the point of view of the operating condition of current domestic denitrating system, denitrating system controls the control generally use for ammonia amount substantially
Mode processed, i.e. fixed molar ratio control mode (Constant Mole Ratio Control).System is pressed under the control mode
According to fixed NH3/NOxMolar ratio removes NO in flue gasx.For ammonia adjustment actuating mechanism for ammonia flow as single loop PID control
Process values (PV), each executing agency it is as follows for ammonia flow setting value (SP) Computing Principle：
(1)NOxMass flow=flue gas flow × entrance NOxConcentration；
(2) reducing agent mass flow=NOxMass flow × ammonia nitrogen molar ratio × conversion coefficient；
(3)
This control strategy is the adjustable unity loop control strategy of setting value, and control principle block diagram is as shown in Figure 1.Its
In, the numerical value of flue gas flow can be directly obtained by flowmeter measurement, can also be obtained according to the corresponding theoretical value of boiler load.
Also there is partial denitrification system that the control mode of double PID bunch grade adjustments is respectively adopted to the sides A, B side reaction devices to realize
To the control for ammonia amount.Main PID regulator adjusts denitration efficiency or SCR reactor outlets NOxConcentration (hereinafter referred to as exports NOxIt is dense
Degree), secondary PID regulator is adjusted for ammonia flow.In order to make automatic loop be enable to respond quickly in load change, enhancing is automatic to return
The stability on road, this bunch grade adjustment circuit usually can also introduce boiler load as feed-forward signal.Unilateral double PID bunch grade adjustments
The functional block diagram of control mode is as shown in Figure 2.
The control strategy of fixed molar ratio is feasible in theory, but during practical application, often because of flue gas
Reasons that amount fluctuation is excessive, governing response is slow etc. cause automatic loop input unstable, often occur reducing agent spray into it is very few or
Excessive phenomenon is sprayed into, the operation steady in a long-term of denitrating system is seriously affected, not only increases the working strength of operations staff, and
And also greatly increase operating cost.
And the control strategy of double PID bunch grade adjustments, it is adjusted although with double PID adjustment device, and it is negative to introduce boiler
Lotus feed-forward signal improves the control effect of automatic loop to a certain extent, but due to not eliminating other disturbing factor bands
The influence come still has the problems such as amplitude of accommodation is bigger than normal, regulating cycle is long in actual application.
Ontological property of denitration CEMS equipment faults and adjustment actuating mechanism etc. is excluded to the influence for ammonia automatic loop, is led to
Systematic Analysis is crossed, causes the main reason for poor for ammonia automatic loop regulation quality that can be summarized as the following：
(1) flue gas flow parameter is inaccurate.In practical applications, acquisition or root are either directly measured by instrument
It is obtained according to the corresponding theoretical value of boiler load, obtained flue gas flow data can not all accurately reflect flue gas stream in actual condition
The real change situation of amount.Especially by the flue gas flow that instrument measurement obtains, even instrument itself is working properly, survey
Magnitude also can frequent fluctuation, lead to adjust output valve and fluctuate up and down frequent, or even true flue gas flow is increasing sometimes
(boiler load and entrance NO can be passed throughxThe variation of concentration judges), and the measured value of instrument is reducing or is being basically unchanged, in turn
It adjusts output when leading to increase reducing agent straying quatity not increase but so that control effect is very undesirable.And root
The flue gas flow obtained according to the corresponding theoretical value of boiler load is also inaccurate, because even in the identical feelings of boiler load
Under condition, exhaust gas volumn is also different caused by different as-fired coal matter and combustion conditions.
(2) automatic loop response is slow.This is because caused by process system itself, because chemical reaction needs centainly
Time, the reason that process pipe, installations and facilities are arranged in addition so that it is anti-that the reducing agent just sprayed into cannot participate in reduction at once
It answers, and needs even longer time a few minutes that can just make outlet NOxConcentration reduces.It in this case, if will be automatic for ammonia
The adjustment effect in circuit enhances, and will result in overshoot；On the contrary, if adjustment effect weakened, it just will appear control lag, automatic
Not the phenomenon that circuit is not caught up with.
(3) automatic loop disturbing factor is more.When boiler load changes, the significantly change of exhaust gas volumn can be caused so that SCR
The NO of reactor inletxFluctuation therewith is measured, and then the adjusting of automatic loop is caused to export frequent fluctuation up and down.In addition,
When boiler load is substantially steady, the variation of as-fired coal matter and firing optimization can also make the NO of SCR reactor inletsxAmount becomes
Change, and then influences the regulating effect of automatic loop.CEMS equipment is when carrying out the periodic maintenance tasks such as automatic back blow, calibration, meeting
The data interlock that CEMS system externals are transmitted is kept, different equipment manufacturers, and CEMS safeguards the required time also automatically
Difference, some CEMS equipment only need to make data to be kept for 1~3 minute, and some then needs to keep data 10 minutes or more；For for ammonia
For automatic loop, the numerical value after holding is exactly a definite value, if automatically adjusted for a long time according to this numerical value, once it protects
The CEMS data held are released, and discharge front and back numerical bias often very greatly, this will result in the disturbance of phase step type；If
Locking keeps the output valve of PID regulator that can equally cause then after the data kept are released while CEMS data are kept
Automatic loop vibrates, and automatic loop generally requires to be lot more time to be adjusted to stable state, or even it sometimes appear that deviation is excessive, nothing
The phenomenon that method adjustment is returned.
Invention content
To solve the above problems, the purpose of the present invention is to provide a kind of elimination disturbing factor, reaching and accurately controlling purpose
Thermal power plant's denitration for ammonia automatic loop control method and control system.
The present invention provides a kind of thermal power plant's denitrations for the control method of ammonia automatic loop, is returned by master control for ammonia automatic loop
Road and auxiliary control circuit are constituted, and the main control loop takes the outlet NO of SCR reactorsxConcentration is adjusted as process values, described
Auxiliary control circuit includes multiple single control circuits, and each single control circuit, which takes, to be adjusted for ammonia flow as process values, and step is specifically included
Suddenly：
Step 1, the corresponding required radix for ammonia amount under different load is obtained by first function F1 (X)；
Step 2, by judging that selection obtains the process values of the PID regulator of main control loop：
If A side outlets and B side outlets are normal, A side outlets NOxConcentration value and B side outlets NOxConcentration value passes through
One analog quantity alternative module carries out Selecting operation, the outlet NO of the first analog quantity alternative module outputxConcentration value is made
For the process values of the PID regulator of main control loop；
If the CEMS systems of A side outlets are safeguarded in calibration, B side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
If the CEMS systems of B side outlets are safeguarded in calibration, A side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
Step 3, the outlet NO that will be obtained in step 2xConcentration value obtains outlet NO by third function F3 (X)xConcentration value
The corresponding first output compensating parameter of friction speed change rate, and export compensating parameter using described first and participated in as feed-forward signal
Adjust operation；
Step 4, the outlet NO that the PID regulator of the main control loop will obtain in step 2xIn concentration value and step 3
To the first output compensating parameter operation is adjusted, needed for the output valve after operation is obtained by second function F2 (X)
For the correction factor of ammonia amount；
Step 5, the correction factor that the cardinal sum step 4 that step 1 obtains obtains is multiplied to obtain for ammonia amount value；
Step 6, the percentage speed variation of the boiler load is obtained into different percentage speed variations by the 5th function F5 (X)
Corresponding second output compensating parameter；
Step 7, the side entrances A NOxConcentration value and the side entrances B NOxConcentration value is selected by the second analog quantity alternative module
Select operation, the value of the second analog quantity alternative module output alternatively after entrance NOxConcentration value, by the entrance of output
NOxThe percentage speed variation of concentration value obtains the corresponding third output compensation of different percentage speed variations by the 4th function F4 (X)
Parameter；
Step 8, it exports compensating parameter by described second and the third output compensating parameter and step 5 obtains for ammonia amount
Value be added, obtain it is actually required for ammonia amount, and by this digital average distribute to input automatically for ammonia adjustment actuating mechanism, obtain
To each executing agency for ammonia flow setting value, as the PID regulator in each single control circuit in auxiliary control circuit for ammonia stream
Measure setting value；
Step 9, the setting for ammonia flow for ammonia flow and PID regulator in each single control circuit by each single control circuit
Operation is adjusted in definite value, obtain it is each for ammonia adjustment actuating mechanism for ammonia adjust flow.
As a further improvement on the present invention, in step 2, the outlet NO of the first analog quantity alternative module outputx
Concentration value is A side outlets NOxConcentration value and B side outlets NOxMaximum value in concentration value or A side outlets NOxConcentration value and the sides B go out
Mouth NOxMinimum value in concentration value or A side outlets NOxConcentration value and B side outlets NOxThe average value of concentration value.
As a further improvement on the present invention, in step 7, the entrance NO of the second analog quantity alternative module outputx
Concentration value is the side entrances A NOxConcentration value and the side entrances B NOxMaximum value in concentration value or the side entrances A NOxConcentration value and the sides B enter
Mouth NOxMinimum value in concentration value or the side entrances A NOxConcentration value and the side entrances B NOxThe average value of concentration value.
The present invention also provides a kind of thermal power plant's denitrations for the control system of ammonia automatic loop, for ammonia automatic loop by master control
Circuit and auxiliary control circuit are constituted, and the main control loop takes the outlet NO of SCR reactorsxConcentration is adjusted as process values, institute
It includes multiple single control circuits to state auxiliary control circuit, and each single control circuit, which takes, to be adjusted for ammonia flow as process values, is specifically included：
First computing module obtains the corresponding required radix for ammonia amount under different load by first function F1 (X)；
Selecting module is judged, by judging that selection obtains the process values of the PID regulator of main control loop：
If A side outlets and B side outlets are normal, A side outlets NOxConcentration value and B side outlets NOxConcentration value passes through
One analog quantity alternative module carries out Selecting operation, the outlet NO of the first analog quantity alternative module outputxConcentration value is made
For the process values of the PID regulator of main control loop；
If the CEMS systems of A side outlets are safeguarded in calibration, B side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
If the CEMS systems of B side outlets are safeguarded in calibration, A side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
First compensating module, by the outlet NO of the judgement selecting module outputxConcentration value is obtained by third function F3 (X)
To outlet NOxThe corresponding first output compensating parameter of friction speed change rate of concentration value, and the first output compensation is joined
Number participates in adjusting operation as feed-forward signal；
First adjustment module, the PID regulator of the main control loop is by the outlet NO of the judgement selecting module outputxIt is dense
Operation is adjusted in the first output compensating parameter obtained in degree and first compensating module, and the output valve after operation is logical
It crosses second function F2 (X) and obtains the required correction factor for ammonia amount；
Second computing module, the amendment that the first adjustment module described in cardinal sum that first computing module obtains is obtained
Multiplication is obtained for ammonia amount value；
The percentage speed variation of the boiler load is obtained different speed by the second compensating module by the 5th function F5 (X)
Spend the corresponding second output compensating parameter of change rate；
Third compensating module, the side entrances A NOxConcentration value and the side entrances B NOxConcentration value passes through the second analog quantity alternative mould
Block carries out Selecting operation, the value of the second analog quantity alternative module output alternatively after entrance NOxConcentration value, will be defeated
The entrance NO gone outxThe percentage speed variation of concentration value obtains the corresponding third of different percentage speed variations by the 4th function F4 (X)
Export compensating parameter；
Third computing module exports compensating parameter by described second and third output compensating parameter is transported with described second
That calculates that module obtains is added for ammonia amount value, obtains actually required for ammonia amount, and it is automatic that this digital average distributed to input
For ammonia adjustment actuating mechanism, each executing agency is obtained for ammonia flow setting value, as in each single control circuit in auxiliary control circuit
PID regulator for ammonia flow setting value；
Second adjustment module, by the confession for the PID regulator in ammonia flow and each single control circuit in each single control circuit
Operation is adjusted in ammonia flow setting value, obtain it is each for ammonia adjustment actuating mechanism for ammonia adjust flow.
As a further improvement on the present invention, in the judgement selecting module, the first analog quantity alternative module is defeated
The outlet NO gone outxConcentration value is A side outlets NOxConcentration value and B side outlets NOxMaximum value in concentration value or A side outlets NOxIt is dense
Angle value and B side outlets NOxMinimum value in concentration value or A side outlets NOxConcentration value and B side outlets NOxThe average value of concentration value.
As a further improvement on the present invention, in the third compensating module, the second analog quantity alternative module is defeated
The entrance NO gone outxConcentration value is the side entrances A NOxConcentration value and the side entrances B NOxMaximum value in concentration value or the side entrances A NOxIt is dense
Angle value and the side entrances B NOxMinimum value in concentration value or the side entrances A NOxConcentration value and the side entrances B NOxThe average value of concentration value.
Beneficial effects of the present invention are：By multiple functional relations, by boiler load, entrance NOxConcentration, outlet NOxConcentration
Influence of the disturbance to automatic control loop caused by equal Parameters variations is eliminated or is preferably minimized, it can make to return automatically for ammonia
Road early response is quickly adjusted, and is eliminated the influence of disturbed belt, is achieved the purpose that accurately control.
Description of the drawings
Fig. 1 is the functional block diagram of fixed molar ratio control mode；
Fig. 2 is the functional block diagram of unilateral double PID bunch grade adjustment control modes；
Fig. 3 is a kind of flow chart of the thermal power plant's denitration described in the embodiment of the present invention for the control method of ammonia automatic loop；
Fig. 4 is the main control loop functional block diagram described in the embodiment of the present invention；
Fig. 5 is the auxiliary control circuit theory block diagram described in the embodiment of the present invention；
Fig. 6 is the biasing debugging functions functional block diagram described in the embodiment of the present invention；
Fig. 7 is a kind of structural frames of the thermal power plant's denitration described in the embodiment of the present invention for the control system of ammonia automatic loop
Figure.
Specific implementation mode
It is described in further detail below by specific embodiment and in conjunction with attached drawing to the present invention.
Embodiment 1, as shown in figure 3, a kind of control method of the thermal power plant's denitration of the embodiment of the present invention for ammonia automatic loop,
It is made of main control loop and auxiliary control circuit for ammonia automatic loop, main control loop takes the outlet NO of SCR reactorsxConcentration is as process
Value is adjusted, and auxiliary control circuit includes multiple single control circuits, and each single control circuit, which takes, to be adjusted for ammonia flow as process values,
Specifically include step：
Step 1, the corresponding required radix for ammonia amount under different load is obtained by first function F1 (X)；
Step 2, by judging that selection obtains the process values of the PID regulator of main control loop：
If A side outlets and B side outlets are normal, A side outlets NOxConcentration value and B side outlets NOxConcentration value passes through
One analog quantity alternative module carries out Selecting operation, and the first analog quantity alternative module exports A side outlets NOxConcentration value and the sides B
Export NOxMaximum value in concentration value or A side outlets NOxConcentration value and B side outlets NOxMinimum value in concentration value or A side outlets
NOxConcentration value and B side outlets NOxProcess values of the average value of concentration value as the PID regulator of main control loop；
If the CEMS systems of A side outlets are safeguarded in calibration, B side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
If the CEMS systems of B side outlets are safeguarded in calibration, A side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
Step 3, the outlet NO that will be obtained in step 2xConcentration value obtains outlet NO by third function F3 (X)xConcentration value
The corresponding first output compensating parameter of friction speed change rate, and participate in adjusting using the first output compensating parameter as feed-forward signal
Operation；
Step 4, the outlet NO that the PID regulator of main control loop will obtain in step 2xIt is obtained in concentration value and step 3
Operation is adjusted in first output compensating parameter, and the output valve after operation is obtained required for ammonia amount by second function F2 (X)
Correction factor；
Step 5, the correction factor that the cardinal sum step 4 that step 1 obtains obtains is multiplied to obtain for ammonia amount value；
Step 6, the percentage speed variation of boiler load different percentage speed variations is obtained by the 5th function F5 (X) to correspond to
Second output compensating parameter；
Step 7, the side entrances A NOxConcentration value and the side entrances B NOxConcentration value is selected by the second analog quantity alternative module
Operation is selected, the second analog quantity alternative module exports A side entrance NOxConcentration value and the side entrances B NOxMaximum value in concentration value or A
Side entrance NOxConcentration value and the side entrances B NOxMinimum value in concentration value or the side entrances A NOxConcentration value and the side entrances B NOxConcentration
The average value of value alternatively after entrance NOxConcentration value, by the entrance NO of outputxThe percentage speed variation of concentration value passes through the 4th
Function F4 (X) obtains the corresponding third output compensating parameter of different percentage speed variations；
Step 8, the second output compensating parameter and third output compensating parameter are added with what step 5 obtained for ammonia amount value,
Obtain it is actually required for ammonia amount, and by this digital average distribute to input automatically for ammonia adjustment actuating mechanism, obtain each
Executing agency sets for ammonia flow setting value, as the PID regulator in each single control circuit in auxiliary control circuit for ammonia flow
Value；
Step 9, the setting for ammonia flow for ammonia flow and PID regulator in each single control circuit by each single control circuit
Operation is adjusted in definite value, obtain it is each for ammonia adjustment actuating mechanism for ammonia adjust flow.
As shown in Figure 4 and Figure 5, boiler load is determined corresponding required for ammonia under different load by first function F1 (X)
The radix of amount.In Fig. 4,Indicate percentage speed variation.The PID regulator of main control loop is to export NOxConcentration as process variable into
Row adjusts operation, and output valve determines the required correction factor for ammonia amount by second function F2 (X).Radix and correction factor phase
Multiply and can be obtained actually required for ammonia amount, then this digital average is distributed into the automatic executing agency of each input, as auxiliary
Control the PID regulator in circuit in each single control circuit for ammonia flow setting value.Export NOxThe percentage speed variation of concentration passes through
Third function F3 (X) determines the corresponding first output compensating parameter of different percentage speed variations, and participates in adjusting as feed-forward signal
Save operation.Entrance NOxThe percentage speed variation of concentration determines the corresponding third of different percentage speed variations by the 4th function F4 (X)
Export compensating parameter；The percentage speed variation of boiler load determines that different percentage speed variations is corresponding by the 5th function F5 (X)
Second output compensating parameter.
Wherein, first function F1 (X), second function F2 (X), third function F3 (X), the 4th function F4 (X) and the 5th letter
The parameter value such as table 1 of number F5 (X).In first function F1 (X), X is boiler load, and Y is the required radix for ammonia amount.Second letter
In number F2 (X), X is master control PID regulator output valve, and Y is the required correction factor for ammonia amount.In third function F3 (X), X is
Export NOxThe percentage speed variation of concentration, Y are the first output compensating parameter.In 4th function F4 (X), X is entrance NOxThe speed of concentration
Change rate is spent, Y is that third exports compensating parameter.In 5th function F5 (X), X is the percentage speed variation of boiler load, Y second
Export compensating parameter.In the value of the X of the third function F3 (X) of table 1, the 4th function F4 (X) and the 5th function F5 (X), just
Number indicates the percentage speed variation risen, the percentage speed variation that negative number representation declines.
Pass through first function F1 (X), second function F2 (X), third function F3 (X), the 4th function F4 (X) and the 5th function
F5 (X), can be by boiler load, entrance NOxConcentration, outlet NOxInfluence of the disturbance factors such as concentration to automatic control loop eliminate or
Person is preferably minimized.
Table 1
The problem of being safeguarded for the calibration of CEMS system at regular intervals, may be used the control model of multilayer selection, i.e. normal condition
It is lower to use A side outlets, B side outlets NOxConcentration by the first analog quantity alternative module come output valve, as main control loop
The process values of PID regulator participate in adjusting operation；When A side outlet CEMS system calibrations are safeguarded, then B side outlets NO is selectedxIt is dense
Spend the process values as main control loop PID regulator；Similarly, when B side outlet CEMS system calibrations are safeguarded, then the sides A is selected to go out
Mouth NOxProcess values of the concentration as main control loop PID regulator.Because entrance CEMS system calibrations safeguard that the control to this strategy is returned
Road influences very little, therefore does not consider.For A side outlets, B side outlet CEMS systems may there is a situation where calibrations to safeguard simultaneously,
The time that adjustable outlet CEMS system at regular intervals calibration is safeguarded, the timing node that the two side outlet CEMS system calibrations that are staggered are safeguarded,
The case where avoiding two side outlet CEMS systems while safeguarding.
In view of the operation conditions of A side reactions device, B side reaction devices may be different, ammonia is needed so as to cause both sides are actual
It measures inconsistent；If only simple mean allocation, it just will appear a certain side reaction device reducing agent and spray into excessive phenomenon.Cause
This, after total each executing agency's flow setting value for the acquisition of ammonia flow mean allocation, and enters each in the setting value
Before the PID regulator of single control circuit, addition biasing debugging functions are, it can be achieved that A side reactions device and B side reactions device are kept away on demand for ammonia
Exempt from the case where unilateral reactor crosses spray to occur.The present invention biasing debugging functions functional block diagram as shown in fig. 6, principle of operation such as
Under：
CGao Xuan=Max (CThe sides A, CThe sides B)；
Δ1=CGao Xuan- CThe sides A；
Δ2=CGao Xuan- CThe sides B；
Wherein：CThe sides AFor A side outlet NOx concentration values, CThe sides BFor B side outlet NOx concentration values.
Logic is selected to select the maximum value in the two by height A side outlets NOx concentration value, B side outlets NOx concentration value, it will
This value makes the difference with A side outlets NOx concentration value and B side outlet NOx concentration values respectively and obtains Δ1And Δ2.If Δ1＜ 1, then sides A
It is not corrected for ammonia amount, i.e., the sides A are 0 for the correction value of ammonia amount；If Δ1＞ 1 is then determined according to the 6th function F6 (X) different
Δ1It is worth decrement of the corresponding sides A for ammonia amount.Similarly, if Δ2＜ 1, then the sides B do not corrected for ammonia amount, i.e. the sides B repairing for ammonia amount
Positive value is 0；If Δ2＞ 1 then determines different Δs according to the 7th function F7 (X)2It is worth decrement of the corresponding sides B for ammonia amount.
Each executing agency that the output valve of 6th function F6 (X) and the 7th function F7 (X) is acquired with main control loop respectively is for ammonia flow
Setting value is added, to obtain revised each executing agency for ammonia flow setting value.6th function F6 (X) and the 7th function
The parameter value of F7 (X) such as table 2.
Table 2
| Parameter | F6(X) | F7(X) |
| X1 | 1 | 1 |
| Y1 | 0 | 0 |
| X2 | 5 | 5 |
| Y2 | -10 | -10 |
| X3 | 10 | 10 |
| Y3 | -20 | -20 |
| X4 | 20 | 20 |
| Y4 | -25 | -25 |
| X5 | 30 | 30 |
| Y5 | -30 | -30 |
| X6 | 40 | 40 |
| Y6 | -35 | -35 |
In table 2, in the 6th function F6 (X), X is Δ1, Y is different Δ1It is worth decrement of the corresponding sides A for ammonia amount.The
In seven function F7 (X), X is Δ2, Y is different Δ2It is worth decrement of the corresponding sides B for ammonia amount.
Since A side reaction device entrances in urea method denitrating technique and B side reaction device inlet ducts are to adjust door manually,
The biasing debugging functions are usually only applicable to liquid ammonia process for caustic soda purification denitrating technique.
Embodiment 2, as shown in fig. 7, the present invention also provides a kind of thermal power plant's denitrations for the control system of ammonia automatic loop,
It is made of main control loop and auxiliary control circuit for ammonia automatic loop, main control loop takes the outlet NO of SCR reactorsxConcentration is as process
Value is adjusted, and auxiliary control circuit includes multiple single control circuits, and each single control circuit, which takes, to be adjusted for ammonia flow as process values,
It specifically includes：
First computing module obtains the corresponding required radix for ammonia amount under different load by first function F1 (X)；
Selecting module is judged, by judging that selection obtains the process values of the PID regulator of main control loop：
If A side outlets and B side outlets are normal, A side outlets NOxConcentration value and B side outlets NOxConcentration value passes through
One analog quantity alternative module carries out Selecting operation, and the first analog quantity alternative module exports A side outlets NOxConcentration value and the sides B
Export NOxMaximum value in concentration value or A side outlets NOxConcentration value and B side outlets NOxMinimum value in concentration value or A side outlets
NOxConcentration value and B side outlets NOxProcess values of the average value of concentration value as the PID regulator of main control loop；
If the CEMS systems of A side outlets are safeguarded in calibration, B side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
If the CEMS systems of B side outlets are safeguarded in calibration, A side outlets NO is selectedxConcentration value is as main control loop
The process values of PID regulator；
First compensating module will determine that the outlet NO of selecting module outputxConcentration value is gone out by third function F3 (X)
Mouth NOxThe corresponding first output compensating parameter of friction speed change rate of concentration value, and using the first output compensating parameter as before
Feedback signal participates in adjusting operation；
First adjustment module, the PID regulator of main control loop will determine that the outlet NO of selecting module outputxConcentration and first
Operation is adjusted in the first output compensating parameter obtained in compensating module, and the output valve after operation passes through second function F2 (X)
For the correction factor of ammonia amount needed for obtaining；
Second computing module, the correction factor that the first adjustment module of cardinal sum that the first computing module obtains is obtained are multiplied
It obtains for ammonia amount value；
The percentage speed variation of boiler load is obtained different speed by the 5th function F5 (X) and become by the second compensating module
The corresponding second output compensating parameter of rate；
Third compensating module, the side entrances A NOxConcentration value and the side entrances B NOxConcentration value passes through the second analog quantity alternative mould
Block carries out Selecting operation, and the second analog quantity alternative module exports A side entrance NOxConcentration value and the side entrances B NOxIn concentration value
Maximum value or the side entrances A NOxConcentration value and the side entrances B NOxMinimum value in concentration value or the side entrances A NOxConcentration value and the sides B enter
Mouth NOxThe average value of concentration value alternatively after entrance NOxConcentration value, by the entrance NO of outputxThe percentage speed variation of concentration value
The corresponding third of different percentage speed variations, which is obtained, by the 4th function F4 (X) exports compensating parameter；
Third computing module obtains the second output compensating parameter and third output compensating parameter with the second computing module
For ammonia amount value be added, obtain it is actually required for ammonia amount, and by this digital average distribute to input automatically for ammonia adjust execute
Mechanism obtains each executing agency for ammonia flow setting value, as the PID regulator in each single control circuit in auxiliary control circuit
For ammonia flow setting value；
Second adjustment module, by the confession for the PID regulator in ammonia flow and each single control circuit in each single control circuit
Operation is adjusted in ammonia flow setting value, obtain it is each for ammonia adjustment actuating mechanism for ammonia adjust flow.
The regulating effect for ammonia automatic loop of the present invention is excellent, is provided for safe and stable, the economical operation of denitrating system
It ensures.The control method of the present invention can reach every Con trolling index, preferably meet wanting for SCR denitration automation control
It asks, for SCR denitration system, there is stronger versatility and practicability.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this field
For art personnel, the invention may be variously modified and varied.All within the spirits and principles of the present invention, any made by repair
Change, equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (6)
1. a kind of thermal power plant's denitration is for the control method of ammonia automatic loop, which is characterized in that for ammonia automatic loop by main control loop
It is constituted with auxiliary control circuit, the main control loop takes the outlet NO of SCR reactorsxConcentration value is adjusted as process values, described
Auxiliary control circuit includes multiple single control circuits, and each single control circuit, which takes, to be adjusted for ammonia flow as process values, and step is specifically included
Suddenly：
Step 1, the corresponding required radix for ammonia amount under different load is obtained by first function F1 (X)；
Step 2, by judging that selection obtains the process values of the PID regulator of main control loop：
If A side outlets and B side outlets are normal, A side outlets NOxConcentration value and B side outlets NOxConcentration value passes through the first mould
Analog quantity alternative module carries out Selecting operation, the outlet NO of the first analog quantity alternative module outputxConcentration value is as master
Control the process values of the PID regulator in circuit；
If the CEMS systems of A side outlets are safeguarded in calibration, PID tune of the B side outlets NOx concentration value as main control loop is selected
Save the process values of device；
If the CEMS systems of B side outlets are safeguarded in calibration, PID tune of the A side outlets NOx concentration value as main control loop is selected
Save the process values of device；
Step 3, the outlet NO that will be obtained in step 2xConcentration value obtains outlet NO by third function F3 (X)xThe difference of concentration value
The corresponding first output compensating parameter of percentage speed variation, and export compensating parameter using described first and participate in adjusting as feed-forward signal
Operation；
Step 4, the outlet NO that the PID regulator of the main control loop will obtain in step 2xThe institute obtained in concentration value and step 3
It states the first output compensating parameter and operation is adjusted, the output valve after operation is obtained required for ammonia amount by second function F2 (X)
Correction factor；
Step 5, the correction factor that the cardinal sum step 4 that step 1 obtains obtains is multiplied to obtain for ammonia amount value；
Step 6, the percentage speed variation of the boiler load different percentage speed variations is obtained by the 5th function F5 (X) to correspond to
Second output compensating parameter；
Step 7, the side entrances A NOxConcentration value and the side entrances B NOxConcentration value carries out selection fortune by the second analog quantity alternative module
Calculate, the value of the second analog quantity alternative module output alternatively after entrance NOxConcentration value, by the entrance NO of outputxIt is dense
The percentage speed variation of angle value obtains the corresponding third of different percentage speed variations by the 4th function F4 (X) and exports compensating parameter；
Step 8, it exports compensating parameter by described second and the third output compensating parameter and step 5 obtains for ammonia amount value phase
Add, obtain actually required for ammonia amount, and this digital average is distributed into input automatically for ammonia adjustment actuating mechanism, obtained every
A executing agency is for ammonia flow setting value, as being set for ammonia flow for the PID regulator in each single control circuit in auxiliary control circuit
Definite value；
Step 9, by each single control circuit for the PID regulator in ammonia flow and each single control circuit for ammonia flow setting value
Operation is adjusted, obtain it is each for ammonia adjustment actuating mechanism for ammonia adjust flow.
2. control method according to claim 1, which is characterized in that in step 2, the first analog quantity alternative module
The outlet NO of outputxConcentration value is A side outlets NOxConcentration value and B side outlets NOxMaximum value in concentration value or A side outlets NOx
Concentration value and B side outlets NOxMinimum value in concentration value or A side outlets NOxConcentration value and B side outlets NOxConcentration value is averaged
Value.
3. control method according to claim 1, which is characterized in that in step 7, the second analog quantity alternative module
The entrance NO of outputxConcentration value is the side entrances A NOxConcentration value and the side entrances B NOxMaximum value in concentration value or the side entrances A NOx
Concentration value and the side entrances B NOxMinimum value in concentration value or the side entrances A NOxConcentration value and the side entrances B NOxConcentration value is averaged
Value.
4. a kind of thermal power plant's denitration is for the control system of ammonia automatic loop, which is characterized in that for ammonia automatic loop by main control loop
It is constituted with auxiliary control circuit, the main control loop takes the outlet NO of SCR reactorsxConcentration is adjusted as process values, described auxiliary
It includes multiple single control circuits to control circuit, and each single control circuit, which takes, to be adjusted for ammonia flow as process values, is specifically included：
First computing module obtains the corresponding required radix for ammonia amount under different load by first function F1 (X)；
Selecting module is judged, by judging that selection obtains the process values of the PID regulator of main control loop：
If A side outlets and B side outlets are normal, A side outlets NOxConcentration value and B side outlets NOxConcentration value passes through the first mould
Analog quantity alternative module carries out Selecting operation, the outlet NO of the first analog quantity alternative module outputxConcentration value is as master
Control the process values of the PID regulator in circuit；
If the CEMS systems of A side outlets are safeguarded in calibration, B side outlets NO is selectedxPID tune of the concentration value as main control loop
Save the process values of device；
If the CEMS systems of B side outlets are safeguarded in calibration, A side outlets NO is selectedxPID tune of the concentration value as main control loop
Save the process values of device；
First compensating module, by the outlet NO of the judgement selecting module outputxConcentration value is gone out by third function F3 (X)
Mouth NOxThe corresponding first output compensating parameter of friction speed change rate of concentration value, and export compensating parameter by described first and make
It participates in adjusting operation for feed-forward signal；
First adjustment module, the PID regulator of the main control loop is by the outlet NO of the judgement selecting module outputxConcentration and
Operation is adjusted in the first output compensating parameter obtained in first compensating module, and the output valve after operation passes through the
Two function F2 (X) obtain the required correction factor for ammonia amount；
Second computing module, the correction factor that the first adjustment module described in cardinal sum that first computing module obtains is obtained
Multiplication is obtained for ammonia amount value；
The percentage speed variation of the boiler load is obtained different speed by the 5th function F5 (X) and become by the second compensating module
The corresponding second output compensating parameter of rate；
Third compensating module, the side entrances A NOxConcentration value and the side entrances B NOxConcentration value by the second analog quantity alternative module into
Row Selecting operation, the value of the second analog quantity alternative module output alternatively after entrance NOxConcentration value, by output
Entrance NOxThe percentage speed variation of concentration value obtains the corresponding third of different percentage speed variations by the 4th function F4 (X) and exports
Compensating parameter；
Third computing module exports compensating parameter and third output compensating parameter and the second operation mould by described second
Block obtain for ammonia amount value be added, obtain it is actually required for ammonia amount, and by this digital average distribute to input automatically for ammonia
Adjustment actuating mechanism obtains each executing agency for ammonia flow setting value, as the PID in each single control circuit in auxiliary control circuit
Adjuster for ammonia flow setting value；
Second adjustment module, by each single control circuit for the PID regulator in ammonia flow and each single control circuit for ammonia stream
Amount setting value operation is adjusted, obtain it is each for ammonia adjustment actuating mechanism for ammonia adjust flow.
5. control system according to claim 4, which is characterized in that in the judgement selecting module, first simulation
Measure the outlet NO of alternative module outputxConcentration value is A side outlets NOxConcentration value and B side outlets NOxMaximum value in concentration value
Or A side outlets NOxConcentration value and B side outlets NOxMinimum value in concentration value or A side outlets NOxConcentration value and B side outlets NOxIt is dense
The average value of angle value.
6. control system according to claim 4, which is characterized in that in the third compensating module, second simulation
Measure the entrance NO of alternative module outputxConcentration value is the side entrances A NOxConcentration value and the side entrances B NOxMaximum value in concentration value
Or the side entrances A NOxConcentration value and the side entrances B NOxMinimum value in concentration value or the side entrances A NOxConcentration value and the side entrances B NOxIt is dense
The average value of angle value.
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| CN106215671B (en) * | 2016-09-09 | 2018-10-16 | 中国大唐集团科学技术研究院有限公司华中分公司 | A kind of thermal power plant's denitration spray ammonia control method and device |
| CN106422709B (en) * | 2016-10-24 | 2019-05-17 | 大唐韩城第二发电有限责任公司 | Thermal power plant's denitrating system sprays ammonia and adjusts autocontrol method |
| CN107967003A (en) * | 2017-03-10 | 2018-04-27 | 邯郸学院 | For the SCR denitration Control Technique in circulating fluidized bed boiler |
| CN106731829A (en) * | 2017-03-31 | 2017-05-31 | 华北电力大学（保定） | Suppress control system and method for the purging on thermal power plant's discharged nitrous oxides influence |
| CN107561941B (en) * | 2017-09-01 | 2021-06-29 | 华北电力大学（保定） | Full-working-condition standard-reaching emission control method for thermal power generating unit denitration system |
| CN107803114B (en) * | 2017-12-04 | 2020-06-16 | 烟台龙源电力技术股份有限公司 | Denitration control system and control method and control device thereof |
| CN109343349B (en) * | 2018-11-01 | 2023-08-22 | 大唐环境产业集团股份有限公司 | SCR flue gas denitration optimal control system and method based on ammonia injection amount compensator |
| 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 |
| CN111895489A (en) * | 2020-06-17 | 2020-11-06 | 天津国电津能滨海热电有限公司 | Enthalpy value calculation-based unit heat supply steam extraction flow measuring method |
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