CN108187492B - Ammonia spraying control method and device - Google Patents

Ammonia spraying control method and device Download PDF

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CN108187492B
CN108187492B CN201810044539.5A CN201810044539A CN108187492B CN 108187492 B CN108187492 B CN 108187492B CN 201810044539 A CN201810044539 A CN 201810044539A CN 108187492 B CN108187492 B CN 108187492B
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concentration
ammonia injection
value
flue gas
controller
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CN108187492A (en
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黄卫剑
万文军
潘凤萍
朱亚清
罗嘉
李锋
陈华忠
庞志强
肖黎
许志斌
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China Southern Power Grid Power Technology Co Ltd
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Guangdong Electric Power Science Research Institute Energy Technology Co Ltd
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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
    • B01D53/90—Injecting reactants
    • 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
    • B01D53/346—Controlling the process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
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    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D11/00—Control of flow ratio
    • G05D11/02—Controlling ratio of two or more flows of fluid or fluent material
    • G05D11/13—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
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    • B01D2258/0283—Flue gases

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Abstract

The embodiment of the invention discloses an ammonia injection control method and device. The ammonia injection control method provided by the invention uses NO of clean flue gas at the outlet of a chimneyxThe measured concentration value is used as a main regulated quantity, and because the smoke at the outlet of the chimney is the smoke finally discharged to the atmosphere, the NO of the clean smoke is ensuredxThe concentration can ensure NO of the smoke discharged into the atmospherexThe concentration is qualified and stable, meanwhile, the clean smoke at the outlet of the chimney has lower dust content and lower temperature because of multiple filtering dust removal and longer smoke path, and NO is detected at the outlet of the chimneyxAt higher concentration, increase NOxThe purging period of the concentration measuring device, the high failure rate caused by high temperature is avoided, and the problem of NO in the current ammonia injection control system is solvedxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system.

Description

Ammonia spraying control method and device
Technical Field
The invention relates to the field of thermal power waste gas treatment, in particular to an ammonia injection control method and device.
Background
Nitrogen oxides (NO for short)x") is one of three pollution emissions of flue gas of thermal power generating units, and China has NO pollution to NOxThe emission concentration has strict emission concentration index requirements. In order to meet the index requirements, the flue gas of the thermal power plant needs to be subjected to dust removal, desulfurization and denitration treatment before being discharged into the atmosphere, wherein the denitration treatment is to reduce NO by a physical or chemical methodxThe concentration of the emission.
Among them, Selective Catalytic Reduction (SCR) is a flue gas denitration method widely used in thermal power plants, and the reducing agent ammonia (NH) used therein3) Nitric Oxide (NO) and nitrogen dioxide (NO) can be mixed at 299-400 deg.C2) Reduction to nitrogen (N)2) While almost no NH occurs3And oxygen (O)2) Thereby reducing NOxThe emission concentration reaches the aim of flue gas denitration.
However, current ammonia injection control systems that control the amount of ammonia injected by the SCR tend to use the NO at the SCR outletxThe concentration is taken as a main regulated quantity, but the smoke at the SCR outlet to the outlet of a chimney discharging to the atmosphere needs to pass through a desulfurization system, a dedusting system and a longer smoke path to control NO at the SCR outletxQualified concentration and NO guarantee of chimney outletxThe concentration is qualified and stable, and simultaneously, because the temperature and the dust concentration at the SCR outlet are high, NO at the SCR outletxThe concentration measuring device has short purging period and high failure rate, and the normal control level of the ammonia spraying control system is seriously influenced.
Thus, current ammonia injection control systems are led to NOxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system.
Disclosure of Invention
The invention provides an ammonia injection control method and device, which solves the problem that the existing ammonia injection control system is used for NOxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system.
The invention provides an ammonia injection control method, which comprises the following steps:
s1: obtaining NO of clean flue gasxConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
s2: will purify NO of the flue gasxConcentration measurement and NO of clean flue gasxThe concentration set value is input into the main controller to obtain the average set value of the ammonia spraying amount.
Preferably, step S1 is preceded by: step S0;
s0: obtaining clean flue gas NOxConcentration object model and unit load characterization parameters according to net flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxController for concentration rise and NOxAnd a controller corresponding to the concentration reduction.
Preferably, step S2 is followed by: step S3 and step S4;
s3: NO discharged from SCR at first sidexConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
s4: and adding the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a first ammonia injection flow value of the first side SCR ammonia injection flow regulating valve, and adding the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a second ammonia injection flow value of the second side SCR ammonia injection flow regulating valve.
Preferably, the clean flue gas NOxThe concentration object model is specifically:
Figure BDA0001550480500000021
where k is the object gain, τ is the object pure delay time, n is the object order, and T is the object time constant.
Preferably, the unit load characterization parameters specifically include: unit load and/or steam flow and/or total fuel flow.
The invention provides an ammonia injection control device, comprising:
a direction judging unit for obtaining NO of the clean smokexConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
an ammonia injection control unit for purifying NO in the flue gasxConcentration measurement and NO of clean flue gasxThe concentration set value is input into the main controller to obtain the average set value of the ammonia spraying amount.
Preferably, the method further comprises the following steps: a parameter setting unit;
a parameter setting unit for obtaining clean flue gas NOxConcentration object model and unit load characterization parameters according to net flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxControl of concentration risePreparation and NOxAnd a controller corresponding to the concentration reduction.
Preferably, the method further comprises the following steps: a bias setting unit and a bias compensation unit;
an offset setting unit for setting NO at the outlet of the first side SCRxConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
and the offset compensation unit is used for adding the average set value of the ammonia injection amount to the offset value of the ammonia injection amount to obtain a first ammonia injection flow value of the first side SCR ammonia injection flow regulating valve and adding the average set value of the ammonia injection amount to the offset value of the ammonia injection amount to obtain a second ammonia injection flow value of the second side SCR ammonia injection flow regulating valve.
Preferably, the clean flue gas NOxThe concentration object model is specifically:
Figure BDA0001550480500000031
where k is the object gain, τ is the object pure delay time, n is the object order, and T is the object time constant.
Preferably, the unit load characterization parameters specifically include: the unit load capacity and/or the steam flow and/or the total fuel flow.
According to the technical scheme, the invention has the following advantages:
the invention provides an ammonia injection control method, which comprises the following steps: s1: obtaining NO of clean flue gasxConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement; s2: will purify NO of the flue gasxConcentration measurement and NO of clean flue gasxConcentration set value input main controllerAnd obtaining an average set value of the ammonia spraying amount.
The ammonia injection control method provided by the invention uses NO of clean flue gas at the outlet of a chimneyxThe measured concentration value is used as a main regulated quantity, and because the smoke at the outlet of the chimney is the smoke finally discharged to the atmosphere, the NO of the clean smoke is ensuredxThe concentration can ensure NO of the smoke discharged into the atmospherexThe concentration is qualified and stable, meanwhile, the clean smoke at the outlet of the chimney has lower dust content and lower temperature because of multiple filtering dust removal and longer smoke path, and NO is detected at the outlet of the chimneyxAt higher concentration, increase NOxThe purging period of the concentration measuring device, the high failure rate caused by high temperature is avoided, and the problem of NO in the current ammonia injection control system is solvedxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
FIG. 1 is a schematic flow chart of an embodiment of an ammonia injection control method according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of another embodiment of an ammonia injection control method according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an embodiment of an ammonia injection control device according to an embodiment of the present invention;
fig. 4 is a schematic configuration diagram of an ammonia injection control device according to an application example of the present invention.
Detailed Description
The embodiment of the invention provides an ammonia injection control method and device, which solve the problem of the current ammonia injection controlSystem for NOxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides an ammonia injection control method, including:
step 101: obtaining NO of clean flue gasxConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
it is to be noted that nitrogen oxide (abbreviated as "NO")x"): refers to a compound consisting of only two elements, nitrogen and oxygen;
common nitrogen oxides include nitric oxide (NO, colorless), nitrogen dioxide (NO)2Reddish brown), nitrous oxide (N)2O) and dinitrogen pentoxide (N)2O5) And the like, wherein nitrogen oxides other than dinitrogen pentoxide which is normally solid are normally gaseous, Nitrogen Oxides (NO) which are air pollutantsx) Often refers to NO and NO2；
Due to NOxIncrease in concentration and NOxThe concentration drop corresponds to different controller parameters, so different controllers are neededThe specific calculation method of the controller parameters is a common technical means, and is not described herein again;
with NOxIncrease in concentration and NOxThe controller corresponding to the concentration reduction can be the same controller with two sets of different parameters or two independent controllers, and the controllers are selected according to requirements in the practical application process.
Step 102: will purify NO of the flue gasxConcentration measurement and NO of clean flue gasxThe concentration set value is input into the main controller to obtain the average set value of the ammonia spraying amount.
It should be noted that the ammonia injection control method provided in this embodiment uses the NO of the clean flue gas at the outlet of the chimneyxThe measured concentration value is used as a main regulated quantity, and because the smoke at the outlet of the chimney is the smoke finally discharged to the atmosphere, the NO of the clean smoke is ensuredxThe concentration can ensure NO of the smoke discharged into the atmospherexThe concentration is qualified and stable, meanwhile, the clean smoke at the outlet of the chimney has lower dust content and lower temperature because of multiple filtering dust removal and longer smoke path, and NO is detected at the outlet of the chimneyxAt higher concentration, increase NOxThe purging period of the concentration measuring device, the high failure rate caused by high temperature is avoided, and the problem of NO in the current ammonia injection control system is solvedxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system.
The above is an embodiment of an ammonia injection control method according to an embodiment of the present invention, and the following is another embodiment of an ammonia injection control method according to an embodiment of the present invention.
Referring to fig. 2, another embodiment of the present invention provides an ammonia injection control method, including:
step 201: obtaining clean flue gas NOxConcentration object model and unit load characterization parameters according to net flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxController model parameter corresponding to concentration decreaseNumber adjustment to obtain NOxController for concentration rise and NOxA controller corresponding to the concentration drop;
it should be noted that the clean flue gas NO corresponding to different unit load characterization parametersxThe concentration object models are not identical, and the clean smoke NO can be obtained through actual measurementxConcentration object model and unit load characterization parameters according to net flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxController for concentration rise and NOxA controller corresponding to the concentration drop;
the parameter setting process can be directly applied to the existing formula, and is not repeated.
Step 202: obtaining NO of clean flue gasxConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the concentration set value, determining whether the first difference value is greater than or equal to 0, if so, executing step 203, otherwise, executing step 204, wherein the NO of the clean flue gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
if the first difference is greater than or equal to 0, NO is indicatedxThe concentration rises, at which point step 203 is executed, using NOxThe controller corresponding to the concentration rise is used as the main controller, and the first difference value is less than 0, which indicates that NO isxThe concentration drops, at which point step 204 is performed, using NOxThe controller corresponding to the concentration drop is used as a main controller.
Step 203: by NOxThe controller corresponding to the concentration rise serves as a main controller;
step 204: by NOxThe controller corresponding to the concentration reduction is used as a main controller;
step 205: will purify NO of the flue gasxConcentration measurement and NO of clean flue gasxInputting the concentration set value into a main controller to obtain an average set value of ammonia spraying amount;
to say thatIt is clear that NO in the smoke will be purifiedxConcentration measurement and NO of clean flue gasxThe concentration set value is input into the main controller to obtain an ammonia injection amount average set value, and the ammonia injection amount of each SCR ammonia injection flow regulating valve can be directly controlled through the ammonia injection amount average set value and can also be further processed.
Step 206: NO discharged from SCR at first sidexConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
in addition, according to NOxThe concentration balance principle needs to perform offset compensation calculation, the second difference is input into an offset controller to obtain an ammonia spraying amount offset value, and the setting method of the offset controller is a common technical means and is not repeated herein;
with two outlets, NO, in a conventional SCR devicexThe principle of concentration balance is that NO at the outlet of the first side SCR and NO at the outlet of the second side SCR are controlled by ammonia injectionxThe concentrations are substantially equal;
such as NO at SCR outlet on one sidexIf the concentration is higher, the ammonia injection quantity of the side is properly increased through an offset loop, so that NO at the SCR outlet of the side is enabled to bexThe concentration is reduced;
or by a bias loop, properly reducing the ammonia injection amount of the other side to ensure NO at the SCR outlet of the other sidexThe concentration increases and decreases. So as to finally make NO at SCR outlets on two sidesxAt substantially equal concentrations
Step 207: and adding the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a first ammonia injection flow value of the first side SCR ammonia injection flow regulating valve, and adding the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a second ammonia injection flow value of the second side SCR ammonia injection flow regulating valve.
It should be noted that, after calculating the ammonia injection amount offset value, the average set value of the ammonia injection amount is added with the ammonia injection amount offset value to obtain a first ammonia injection flow value of the first side SCR ammonia injection flow regulating valve, and the average set value of the ammonia injection amount is added with the ammonia injection amount offset value to obtain a second ammonia injection flow value of the second side SCR ammonia injection flow regulating valve, so that not only are two ammonia injection amount offset values obtainedThe side SCR ammonia injection regulating valve can adjust NO of the clean flue gasxThe concentration rise or fall is corresponding to the increase or decrease of the ammonia injection amount, and the NO of the first side SCR outlet and the NO of the second side SCR outlet can also be enabledxThe concentration is kept in equilibrium.
Further, the clean flue gas NOxThe concentration object model is specifically:
Figure BDA0001550480500000071
where k is the object gain, τ is the object pure delay time, n is the object order, and T is the object time constant.
Note that the clean flue gas NOxThe object gain, the object pure delay time, the object order and the object time constant in the concentration object model can be derived through actual measurements.
Further, the unit load characterization parameters specifically include: unit load and/or steam flow and/or total fuel flow.
It should be noted that the unit load characterization parameters include: the load and/or steam flow and/or total fuel flow of the unit can be directly obtained according to actual working conditions.
The ammonia injection control method provided in this embodiment uses the NO of the clean flue gas at the outlet of the chimneyxThe concentration measured value is taken as the main regulated quantity, because the flue gas at the outlet of the chimney is the flue gas which is finally discharged to the atmosphere and is consistent with the monitoring point of the environmental protection department, the NO of the clean flue gas is ensuredxThe concentration can ensure NO of the smoke discharged into the atmospherexThe concentration is qualified and stable, meanwhile, the clean smoke at the outlet of the chimney has lower dust content and lower temperature because of multiple filtering dust removal and longer smoke path, and NO is detected at the outlet of the chimneyxAt higher concentration, increase NOxThe purging period of the concentration measuring device is shortened, high failure rate caused by high temperature is avoided, and the NO emission of flue gas is improvedxThe stability and the qualification rate of the concentration index solve the problem that the current ammonia injection control system can not realize the NO treatmentxUnstable concentration control and NOxThe concentration measuring device has short period and high failure rate, and influences the normal control of the ammonia spraying control system;
according to the clean smoke NO in each sampling and detecting processxDifferent controllers are selected for the concentration rise or the concentration fall, so that the ammonia injection control method is used for purifying the NO in the flue gasxThe concentration has good adjustment quality in the rising or falling direction;
in each sampling detection process, setting the parameters of the controller according to the change condition of physical quantity (unit load characterization parameters) representing the unit load, so that the unit has good adjustment quality in different load sections;
also according to NOxThe concentration balance principle is provided with a bias controller to realize NO at different SCR outletsxThe concentration is balanced, and the escape rate of ammonia is reduced.
The ammonia injection control method according to the embodiment of the present invention is another embodiment of the ammonia injection control method according to the embodiment of the present invention, and an embodiment of the ammonia injection control apparatus according to the embodiment of the present invention is described below.
Referring to fig. 3, an embodiment of the present invention provides an ammonia injection control apparatus, including:
a direction judging unit 301 for obtaining NO of the clean flue gasxConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
an ammonia injection control unit 302 for purifying NO of the flue gasxConcentration measurement and NO of clean flue gasxThe concentration set value is input into the main controller to obtain the average set value of the ammonia spraying amount.
Further, still include: a parameter setting unit 300;
a parameter setting unit 300 for obtaining clean flue gas NOxConcentration ofObject model and unit load characterizing parameters according to clean flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxController for concentration rise and NOxAnd a controller corresponding to the concentration reduction.
Further, still include: a bias setting unit 303 and a bias compensation unit 304;
an offset setting unit 303 for setting NO at the outlet of the first side SCRxConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
and the offset compensation unit 304 is configured to add the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a first ammonia injection flow value of the first-side SCR ammonia injection flow control valve, and add the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a second ammonia injection flow value of the second-side SCR ammonia injection flow control valve.
Further, the clean flue gas NOxThe concentration object model is specifically:
Figure BDA0001550480500000091
where k is the object gain, τ is the object pure delay time, n is the object order, and T is the object time constant.
Further, the unit load characterization parameters specifically include: the unit load capacity and/or the steam flow and/or the total fuel flow.
Referring to fig. 4, the present invention provides a practical application example of an ammonia injection control device, which includes:
the labels in fig. 4 are: 1. a unit load characterization parameter; 2. NO of clean flue gasxA concentration measurement; 3. NO of clean flue gasxA concentration set value; 4. clean smoke NOxA concentration object model; 5. a parameter setting unit; 6. a direction determination unit; 7. an ammonia injection control unit; 8. an offset setting unit; 9. an adder; 10. A subtractor; 11. a first ammonia injection flow value; 12. a second ammonia injection flow value;
taking an ammonia injection control device implemented by a 660MW ultra-supercritical coal-fired power generating unit as an example, the ammonia injection control device comprises two SCR outlets at the A, B side and two SCR ammonia injection flow regulating valves at the A, B side;
1. according to unit load characterization parameters 1 and clean flue gas NOxThe concentration object model 4 is adjusted to NO in the parameter setting unit 5xController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxController for concentration rise and NOxA controller corresponding to the concentration drop;
2. NO according to clean flue gasxConcentration measurement 2 and NO of clean flue gasxThe concentration set value 3 is judged for NO in the direction judgment unit 6xIf the concentration is rising or falling, the direction determination unit 6 is a switch, and can switch the corresponding controller or controller parameter as the main controller;
3. NO according to clean flue gasxConcentration measurement 2 and NO of clean flue gasxThe concentration set value 3 is input to the master controller selected in the previous step as an input quantity in the ammonia injection control unit 7, and an average set value of the ammonia injection quantity is output;
4. offset setting unit 8 according to NO of first side SCR outletxConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
5. the adder 9 and the subtracter 10 are combined to be offset compensation means, and the adder 9 performs addition to add the ammonia injection amount average set value to the ammonia injection amount offset value to obtain a first ammonia injection flow value 11 of the a-side SCR ammonia injection flow rate control valve, and the subtracter 10 performs subtraction to add the ammonia injection amount average set value to the ammonia injection amount offset value to obtain a second ammonia injection flow value 12 of the B-side SCR ammonia injection flow rate control valve.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (8)

1. An ammonia injection control method, comprising:
s1: obtaining NO of clean flue gasxConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
s2: will purify NO of the flue gasxConcentration measurement and NO of clean flue gasxInputting the concentration set value into a main controller to obtain an average set value of ammonia spraying amount;
s3: NO discharged from SCR at first sidexConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
s4: and adding the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a first ammonia injection flow value of the first side SCR ammonia injection flow regulating valve, and adding the ammonia injection amount offset value to the average ammonia injection amount set value to obtain a second ammonia injection flow value of the second side SCR ammonia injection flow regulating valve.
2. The ammonia injection control method according to claim 1, wherein step S1 is preceded by: step S0;
s0: obtaining clean flue gas NOxConcentration object model and unit load characterization parameters according to net flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxController for concentration rise and NOxAnd a controller corresponding to the concentration reduction.
3. The ammonia injection control method according to claim 2, wherein the clean flue gas NO isxThe concentration object model is specifically:
Figure FDA0002421512990000011
where k is the object gain, τ is the object pure delay time, n is the object order, and T is the object time constant.
4. The ammonia injection control method according to claim 2, wherein the unit load characterization parameters specifically include: unit load and/or steam flow and/or total fuel flow.
5. An ammonia injection control device, comprising:
a direction judging unit for obtaining NO of the clean smokexConcentration measurement of NO in clean flue gasxConcentration measurement minus NO of clean flue gasxObtaining a first difference value from the set concentration value, judging whether the first difference value is greater than or equal to 0, if so, adopting NOxThe controller corresponding to the concentration rise is used as the main controller, if not, NO is adoptedxThe controller corresponding to the concentration drop is used as the main controller, wherein NO of the clean smoke gasxThe concentration measurement being NO at the outlet of the chimneyxA concentration measurement;
an ammonia injection control unit for purifying NO in the flue gasxConcentration measurement and NO of clean flue gasxInputting the concentration set value into a main controller to obtain an average set value of ammonia spraying amount;
an offset setting unit for setting NO at the outlet of the first side SCRxConcentration measurement minus NO at second side SCR outletxObtaining a second difference value by the concentration measurement value, and inputting the second difference value into the offset controller to obtain an ammonia spraying amount offset value;
and the offset compensation unit is used for adding the average set value of the ammonia injection amount to the offset value of the ammonia injection amount to obtain a first ammonia injection flow value of the first side SCR ammonia injection flow regulating valve and adding the average set value of the ammonia injection amount to the offset value of the ammonia injection amount to obtain a second ammonia injection flow value of the second side SCR ammonia injection flow regulating valve.
6. An ammonia injection control apparatus as defined in claim 5, further comprising: a parameter setting unit;
a parameter setting unit for obtaining clean flue gas NOxConcentration object model and unit load characterization parameters according to net flue gas NOxConcentration model and unit load characterization parameter respectively for NOxController model for concentration rise and NOxThe controller model corresponding to the concentration reduction is subjected to parameter setting to obtain NOxController for concentration rise and NOxAnd a controller corresponding to the concentration reduction.
7. The ammonia injection control device of claim 6, wherein the clean flue gas NO isxThe concentration object model is specifically:
Figure FDA0002421512990000021
where k is the object gain, τ is the object pure delay time, n is the object order, and T is the object time constant.
8. The ammonia injection control device according to claim 6, wherein the unit load characterization parameters specifically include: the unit load capacity and/or the steam flow and/or the total fuel flow.
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