CN114545775B - Denitration feedforward control system and method suitable for starting and stopping of coal-fired unit grinding unit - Google Patents
Denitration feedforward control system and method suitable for starting and stopping of coal-fired unit grinding unit Download PDFInfo
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- 238000000227 grinding Methods 0.000 title claims abstract description 116
- 238000000034 method Methods 0.000 title claims abstract description 18
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 134
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 66
- 230000001105 regulatory effect Effects 0.000 claims abstract description 23
- 230000033228 biological regulation Effects 0.000 claims abstract description 8
- 239000003245 coal Substances 0.000 claims description 56
- 238000002347 injection Methods 0.000 claims description 15
- 239000007924 injection Substances 0.000 claims description 15
- 230000009471 action Effects 0.000 claims description 10
- 230000008859 change Effects 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000003801 milling Methods 0.000 claims description 3
- 230000001960 triggered effect Effects 0.000 claims description 3
- 238000010977 unit operation Methods 0.000 claims description 3
- 238000012886 linear function Methods 0.000 claims description 2
- 230000006978 adaptation Effects 0.000 claims 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 11
- 238000005507 spraying Methods 0.000 abstract description 3
- 230000007774 longterm Effects 0.000 abstract description 2
- 238000004445 quantitative analysis Methods 0.000 abstract description 2
- 238000002485 combustion reaction Methods 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000003546 flue gas Substances 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- -1 flue gas nitrogen oxides Chemical class 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000000246 remedial effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/346—Controlling the process
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- B01D53/86—Catalytic processes
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- B01D53/86—Catalytic processes
- B01D53/90—Injecting reactants
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
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- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
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Abstract
The invention discloses a denitration feedforward control system and a denitration feedforward control method which are suitable for starting and stopping of a coal-fired unit grinding set, wherein quantitative analysis is carried out on the influence of starting and stopping of each layer of grinding set of the unit on the concentration of nitrogen oxides generated by a hearth, an ammonia quantity feedforward regulating loop is designed when each layer of grinding set starts and stops, the ammonia quantity feedforward regulating loop participates in the opening regulation of an ammonia spraying valve of an SCR denitration control system, and the serious fluctuation condition of the concentration of generated NOx is compensated by regulating the opening of the valve in advance, so that the problem that denitration is difficult to put into automatic operation during starting and stopping grinding is solved, and the control performance and the system stability of the denitration control system under long-term input are effectively improved.
Description
Technical Field
The invention belongs to the technical field of automatic control of thermal power stations, and particularly relates to a feedforward regulation control system and a feedforward regulation control method for ammonia flow of a denitration system of a coal-fired unit under a specific working condition of starting and stopping a grinding unit.
Background
Nitrogen oxide pollutants (such as NO 2, NO and the like) generated by daily industrial activities are one of the key points of environmental protection and treatment in various countries. The SCR (selective catalytic reduction) denitration system is the most common flue gas denitration technology of domestic coal-fired power plants due to the application characteristics of high denitration efficiency, low operation cost and no secondary pollution, and accordingly the long-period refined optimization control technology of the SCR denitration system is always a continuous concern in the environmental protection field of thermal power units.
The flue gas nitrogen oxides formed in the coal-fired power generation process of the power plant are mainly divided into two types, the first type is NOx generated by burning nitrogen-containing compounds of the fuel, namely fuel NOx, the contents of sulfur, nitrogen, chlorine and other elements contained in different coal types are different, the coal with high heat generation, low ignition point and low nitrogen content is good in combustion characteristics, and the NOx generated concentration in the flue gas after corresponding combustion is relatively low; the second type is NOx formed by oxidizing nitrogen in fuel air at high temperature in the combustion process, called thermal NOx, which is mainly influenced by factors such as combustion temperature, excess air coefficient, staged combustion degree and the like, and can generate larger fluctuation along with different unit operation conditions. Some power plants are influenced by coal quality blended combustion, multiple changes and running modes of grinding groups, the phenomenon that the concentration of NOx generated by a hearth is too high or fluctuation is large frequently occurs, and besides objective factors of coal quality, the combined running mode of different coal mills is one of important reasons for influencing the concentration of the NOx generated in flue gas. If the common front and rear wall opposite-impact type burner is adopted, the 6 coal mills are generally divided into an upper layer, a middle layer and a lower layer, and experiments prove that when the air distribution mode of the boiler is kept unchanged, the initial stage of starting and stopping the upper layer coal mill or the lower layer coal mill can cause the integral flame center in the furnace to move upwards in a short time, the staged combustion capability is weakened along with the upward movement, the generated NOx concentration of a hearth is easy to generate transient sudden change, and the average value of the generated NOx concentration measured by an SCR inlet is also rapidly increased along with the initial stage of starting and stopping the lower layer coal mill; in the initial stage of stopping operation of the upper coal mill or starting of the lower coal mill, the flame center in the hearth moves downwards integrally, the radial staged combustion capacity of the main combustion area of the hearth is enhanced, the combustion condition is well improved, the concentration of generated NOx in the hearth at the moment can instantaneously show a descending trend, and the average value of the concentration of generated NOx measured by the SCR inlet is reduced; the concentration of generated NOx of the hearth is not greatly influenced before and after the middle coal mill is started and stopped, and the concentration of generated NOx measured by the SCR inlet can be basically kept stable.
The deep peak regulation operation modes of many thermal power generating units are put into the current state, the load real-time scheduling is greatly changed, and accordingly, the coal mill is started and stopped more frequently. As the combustion theory analysis shows, the mutation of the concentration of NOx generated in a hearth is very easy to occur at the initial stage of starting and stopping of the grinding set, and in actual operation of many power plants, the increase or decrease rate of the concentration of the generated NOx is too fast to cause great disturbance to an SCR denitration automatic control system, so that automatic control is difficult to follow in time, the phenomenon that the instantaneous value of the concentration of the NOx at an environment-friendly outlet exceeds the standard occurs, operators often release the automatic control of denitration, and an ammonia injection valve is manually and fast opened to inhibit the increase of the concentration of the NOx at the environment-friendly outlet. However, the passive remedial control method cannot effectively prevent and improve the fluctuation condition of the concentration of NOx at the environment-friendly outlet, but is easy to cause exceeding of ammonia escape due to extensive excessive ammonia injection. By adopting the control mode for a long time, the operation control effect of the denitration system cannot be improved, the problem that the outlet of the air preheater is blocked due to ammonium bisulfate deposition caused by excessive ammonia escape is extremely easy, and a great risk is formed for the safe operation of the denitration system and even the whole unit.
Disclosure of Invention
In view of the problems in the prior art, the invention provides a denitration feedforward control system and a denitration feedforward control method which are suitable for starting and stopping of a coal-fired unit grinding set, quantitative analysis is carried out on the influence of starting and stopping of each layer of grinding set of the unit on the concentration of nitrogen oxides generated by a hearth, an ammonia quantity feedforward regulating loop is designed when each layer of grinding set starts and stops, the ammonia quantity feedforward regulating loop participates in the opening regulation of an ammonia spraying valve of an SCR denitration control system, and the serious fluctuation condition of the concentration of generated NOx is compensated by regulating the opening of the valve in advance, so that the problem that denitration is difficult to put into automatic operation during starting and stopping of the unit is solved, and the control performance and the system stability of the denitration control system under long-term investment are effectively improved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A denitration feedforward control system suitable for starting and stopping a coal-fired unit grinding unit is composed of an upper coal feeder operation signal 1 and an upper coal mill operation signal 4 of the unit; a middle layer coal feeder operation signal 2 and a middle layer coal mill operation signal 5; a lower coal feeder operation signal 3 and a lower coal mill operation signal 6; three layers of grinding set start-stop signal output are respectively formed, and for an upper layer of grinding set loop: the upper coal feeder operation signal 1 and the upper coal mill operation signal 4 are calculated through a logic AND gate 7 to obtain upper mill group start-stop signal output, the first path is sent to a mill start-stop long pulse signal generator 8, the mill start-stop long pulse signal generator 11 is disconnected through mill start-stop delay, and finally the upper mill start-stop long pulse signal generator is sent to a DCS system 13 to trigger an upper mill start-stop feedforward pulse 14 to form an upper mill start-stop feedforward loop; the other path is sent to a logic NOT gate 9, and then sent to a grinding stopping delay break generator 12 through a grinding stopping long pulse generator 10, finally sent to a DCS system 13, and triggers an upper layer grinding stopping feedforward pulse 15 to form an upper layer grinding stopping feedforward loop, wherein the control mode of a middle layer grinding set and a lower layer grinding set is the same as that of the upper layer grinding set; in the DCS control system 13, the sum of values calculated by the first adder 20 of the upper layer grinding start feed-forward pulse 14, the upper layer grinding stop feed-forward pulse 15, the middle layer grinding start feed-forward pulse 16, the middle layer grinding stop feed-forward pulse 17, the lower layer grinding start feed-forward pulse 18 and the lower layer grinding stop feed-forward pulse 19 is restrained by the rate limiter 21 and the amplitude limiter 22 in terms of the rate of change and amplitude, and then the final ammonia quantity control command feed-forward value of the unit grinding start-stop is calculated by the ammonia quantity-valve opening conversion module (23), and is superimposed to the ammonia injection regulating valve 26 of the denitration system, and the ammonia quantity flow actually entering the SCR denitration reaction device 27 is controlled by the valve opening.
According to the control method of the denitration feedforward control system suitable for starting and stopping of the coal-fired unit grinding set, the phase and amplitude change trend of NOx concentration measured values of SCR inlets of the unit before and after starting and stopping actions of the unit by utilizing unit operation historical data and different layers of grinding sets are analyzed, specific numerical values of an upper starting and grinding feedforward pulse 14, an upper stopping and grinding feedforward pulse 15, a middle starting and grinding feedforward pulse 16, a middle stopping and grinding feedforward pulse 17, a lower starting and grinding feedforward pulse 18 and a lower stopping and grinding feedforward pulse 19 are set, feedforward continuous acting time is set by utilizing a starting and grinding delay breaking generator 11 and a stopping and grinding delay breaking generator 12, parameter setting can be flexibly modified and adjusted according to system requirements, and further a denitration refined ammonia quantity control effect based on the starting and stopping states of the grinding set is realized.
According to the control method of the denitration feedforward control system suitable for starting and stopping of the coal-fired unit mill group, the coal feeder and the coal mill are classified according to the actual arrangement mode of the unit burner, an upper mill group starting and stopping signal, a middle mill group starting and stopping signal and a lower mill group starting and stopping signal are extracted based on the starting or stopping state of each layer of coal mill and coal feeder, further, when each layer of coal mill and coal feeder is started or stopped, corresponding layers of starting and stopping feedforward pulse are triggered, the sum value of an upper layer starting and stopping feedforward pulse 14, an upper layer stopping feedforward pulse 15, a middle layer starting and stopping feedforward pulse 16, a middle layer stopping feedforward pulse 17, a lower layer starting and stopping feedforward pulse 18 and a lower layer stopping feedforward pulse 19 is calculated in real time, and after speed limit calculation, the total starting and stopping feedforward pulse is converted into an ammonia adjusting valve opening offset delta m mode, and the ammonia spraying adjusting valve 26 is acted on the denitration system to participate in the control of the denitration system.
In the control method, the total start-stop grinding feedforward pulse value TF expression is:
TF＝F1st+F1sp+F2st+F2sp++F3st+F3sp
Wherein: f1st is the upper layer grinding starting feedforward pulse value; f1sp is the upper layer stop-milling feedforward pulse value; f2st is a middle layer grinding starting feedforward pulse value; f2sp is the middle layer stop-grinding feedforward pulse value; f3st is the lower layer grinding starting feedforward pulse value; f3sp is the lower stop-feed pulse value.
The opening offset delta m of the ammonia regulating valve is calculated as:
Wherein: TF is the feedforward pulse value of total start-stop mill, and K is the linear function gain of flow and opening of the ammonia injection valve.
The denitration feedforward control system and method adapting to start and stop of the coal-fired unit grinding unit are characterized in that: when the start-stop actions of different layers of grinding groups trigger the start-stop feedforward loop or stop feedforward loop to output, in the feedforward duration time t, the total start-stop feedforward pulse value is converted into the opening offset delta m of an ammonia regulating valve through speed limiting and amplitude limiting calculation according to the ammonia quantity feedforward quantity change, the opening offset delta m is overlapped to the denitration ammonia injection regulating valve to participate in the actual regulation of the denitration ammonia quantity, after the feedforward duration time t is over, the start-stop feedforward quantity is limited to return to zero at a set speed, and the opening of the denitration system ammonia injection regulating valve is gradually restored to the original controller output value. The original denitration control system is not disturbed, and the undisturbed parallel annealing effect of the start-stop milling feedforward is realized.
Compared with the prior art, the invention has the following advantages:
1. According to the invention, the unit grinding groups are divided into different levels according to the position layout of the burner, corresponding ammonia gas flow regulation compensation is generated by triggering the grinding groups at each level by the starting and stopping signals, and the unit grinding groups are integrated into the original denitration control system, so that the problem of poor investment effect of the denitration automatic control system caused by overlarge concentration fluctuation of generated NOx caused by starting and stopping the grinding groups is effectively solved, and the long-period stable investment of the denitration automatic control system is ensured.
2. According to the invention, based on the analysis of a large number of operating data during the load change of the unit and the change data of the concentration of NOx generated by the hearth before and after the start and stop of different mill groups, the ammonia quantity compensation feedforward required by each mill group in the starting or stopping process is respectively evaluated qualitatively and quantitatively, the action duration, the lifting speed, the amplitude limit value and other parameters of each feedforward quantity can be flexibly set and adjusted, and the great fluctuation change of the concentration of NOx at the SCR inlet is dealt with in advance, so that the concentration of NOx at the SCR outlet is controlled to be kept stable, and the denitration refined ammonia quantity control effect aiming at the start and stop state of the mill groups is realized.
3. The invention reduces the abnormal phenomenon of frequent manual operation of denitration control caused by frequent start and stop of the grinding set in the running process of the machine set to a certain extent. When the NOx concentration at the SCR outlet has the risk of exceeding the standard, the rough control mode of manually and excessively opening the large ammonia injection regulating valve for a long time easily causes excessive ammonia escape, and seriously affects the operation safety of the denitration system. According to the denitration ammonia quantity feedforward control system and method suitable for starting and stopping of the coal-fired unit grinding unit, the required ammonia quantity is finely adjusted in real time according to the SCR inlet NOx concentration value and the outlet NOx concentration feedback value, ammonia is reasonably used, the occurrence of excessive ammonia escaping is greatly reduced, and the operation characteristic and the actual control performance of the unit all-condition denitration system are comprehensively improved.
Drawings
FIG. 1 is a schematic diagram of the control strategy of the present invention.
Wherein, 1 is upper coal feeder operation signal, 2 is middle coal feeder operation signal, 3 is lower coal feeder operation signal, corresponding to the same, 4 is upper coal mill operation signal, 5 is middle coal mill operation signal, 6 is lower coal mill operation signal, 7 is logic AND gate, 8 is start grinding long pulse signal generator, 9 is logic NOT gate, 10 is grinding stop long pulse generator, 11 is start grinding delay break generator, 12 is grinding stop delay break generator, 13 is DCS control system, 14 is upper start grinding feed-forward pulse, 15 is upper stop grinding feed-forward pulse, 16 is middle start grinding feed-forward pulse, 17 is middle stop grinding feed-forward pulse, 18 is lower start grinding feed-forward pulse, 19 is lower stop grinding feed-forward pulse, 20 is adder number one, 21 is rate limiter, 22 is amplitude limiter, 23 is ammonia amount-valve opening conversion module, 24 is instruction number two adder number two, 26 is ammonia injection regulating valve of the denitration system, 27 is SCR denitration reaction device.
Detailed Description
The invention is described in further detail below with reference to the attached drawing figures:
The invention discloses a denitration ammonia amount feedforward control system and method suitable for starting and stopping of a coal-fired unit grinding set, which are shown in a figure 1.
The operation signal 1 of the upper coal feeder of the unit and the operation signal 4 of the upper coal mill; a middle layer coal feeder operation signal 2 and a middle layer coal mill operation signal 5; the lower coal feeder operation signal 3 and the lower coal mill operation signal 6 are calculated by the logic AND gate 7 to form the start-stop signal output of the three-layer mill group, and the start-stop signal output is output to the start-stop feed-forward loop and the stop-stop feed-forward loop of each layer. Taking the upper layer mill group as an example, when the upper layer coal feeder operation signal 1 and the upper layer coal mill operation signal 4 are started, the operation signals are set to 1, the logic AND gate 7 sends out the digital signal 1, then the impulse response of the mill starting long impulse signal generator 8 is triggered, the impulse length can be used for controlling the time interval between the starting moment of the mill group and the feedforward output of the ammonia amount, the impulse falling edge of the mill starting long impulse signal generator 8 will trigger the mill starting delay break generator 11, and the action duration of the ammonia feedforward of the branch is regulated by the setting value of the mill starting delay break generator 11; on the contrary, when any one of the upper coal feeder operation signals 1 and 4 sends out a stop signal 0, the logic AND gate 7 sends out a digital signal 0, and then the digital signal passes through the logic NOT gate 9 to trigger the stop grinding long pulse generator 10, wherein the pulse length can be used for controlling the time interval between the moment of stopping grinding group and the feed-forward output of ammonia quantity, the pulse falling edge of the stop grinding long pulse generator 10 will trigger the stop grinding delay disconnection generator 12, and the set value of the stop grinding delay disconnection generator 12 adjusts the duration of the feed-forward action of the ammonia of the branch. In the ammonia feedforward action duration time, the output values of the upper layer grinding starting feedforward pulse 14, the upper layer grinding stopping feedforward pulse 15, the middle layer grinding starting feedforward pulse 16, the middle layer grinding stopping feedforward pulse 17, the lower layer grinding starting feedforward pulse 18 and the lower layer grinding stopping feedforward pulse 19 are added through a first adder 20 to obtain a total ammonia quantity feedforward value, the total ammonia quantity feedforward value is calculated through a rate limiter 21 and an amplitude limiter 22, then the ammonia quantity feedforward value is converted into a valve opening adjusting bias through an ammonia quantity-valve opening conversion module 23, and the bias and a PID controller instruction 24 are calculated through a second adder 25 to jointly generate an instruction to act on an ammonia injection adjusting valve 26 of a denitration system, so that the ammonia flow actually entering an SCR denitration reaction device 27 is adjusted. When the ammonia feedforward duration time set in the start-up delay off generator 11 or the stop-grinding delay off generator 12 of all the levels is over, the total ammonia feedforward value output by the adder No. 20 will return to zero value at the set rate limit, the instruction of the ammonia injection regulating valve 26 of the denitration system will be restored to the instruction 24 of the PID controller, and the unit grinding group start-up and stop ammonia amount feedforward action flow is over.
Claims (4)
1. A denitration feedforward control system that adaptation coal-fired unit grinds group and opens and stop which characterized in that: firstly, an upper coal feeder operation signal (1) of a unit and an upper coal mill operation signal (4) are used; a middle coal feeder operation signal (2) and a middle coal mill operation signal (5); a lower coal feeder operation signal (3) and a lower coal mill operation signal (6); three layers of grinding set start-stop signal output are respectively formed, and for an upper layer of grinding set loop: the upper coal feeder operation signal (1) and the upper coal mill operation signal (4) are calculated through a logic AND gate (7) to obtain upper grinding group start-stop signal output, the first path is sent to a grinding start-stop long pulse signal generator (8), and finally sent to a DCS (13) after a grinding start delay break generator (11), and an upper grinding start-stop feedforward pulse (14) is triggered to form an upper grinding start-stop feedforward loop; the other path is sent to a logic NOT gate (9), and then sent to a stop-grinding delay break generator (12) through a stop-grinding long pulse generator (10), finally sent to a DCS system (13), and triggers an upper stop-grinding feed-forward pulse (15) to form an upper stop-grinding feed-forward loop, wherein the control mode of a middle layer grinding set and a lower layer grinding set is the same as that of the upper layer grinding set; in a DCS control system (13), an upper layer grinding starting feedforward pulse (14), an upper layer grinding stopping feedforward pulse (15), a middle layer grinding starting feedforward pulse (16), a middle layer grinding stopping feedforward pulse (17), a lower layer grinding starting feedforward pulse (18) and a lower layer grinding stopping feedforward pulse (19) are subjected to numerical summation calculated through a first adder (20), after the rate of change and the constraint of the amplitude are carried out through a rate limiter (21) and an amplitude limiter (22), a final unit ammonia starting and stopping grinding amount control instruction feedforward value is calculated through an ammonia amount-valve opening conversion module (23), and is overlapped to an ammonia injection regulating valve (26) of a denitration system, and the ammonia amount flow actually entering an SCR denitration reaction device (27) is controlled through the valve opening.
2. The control method of the denitration feedforward control system suitable for starting and stopping of the coal-fired unit grinding set, which is characterized by comprising the following steps: analyzing and utilizing the unit operation history data and the phase and amplitude change trend of the unit SCR inlet NOx concentration measured values before and after the start and stop actions of different layers of grinding groups, setting an upper layer grinding starting feedforward pulse (14), an upper layer grinding stopping feedforward pulse (15), a middle layer grinding starting feedforward pulse (16), a middle layer grinding stopping feedforward pulse (17), a lower layer grinding starting feedforward pulse (18) and a lower layer grinding stopping feedforward pulse (19), setting feedforward continuous acting time by utilizing a grinding starting delay breaking generator (11) and a grinding stopping delay breaking generator (12), flexibly modifying and adjusting parameter settings according to system requirements, and further realizing denitration refined ammonia quantity control effect based on the start and stop states of the grinding groups;
According to the actual arrangement mode of the unit burner, classifying coal feeders and coal mills at the upper layer, the middle layer and the lower layer, extracting an upper layer mill group start-stop signal, a middle layer mill group start-stop signal and a lower layer mill group start-stop signal based on the start-stop or stop state of each layer of coal mill and coal feeder, triggering corresponding levels of start-mill feed-forward pulse and stop-mill feed-forward pulse when each layer of coal mill and coal feeder is started or stopped, calculating the sum value of the upper layer start-mill feed-forward pulse (14), the upper layer stop-mill feed-forward pulse (15), the middle layer start-mill feed-forward pulse (16), the middle layer stop-mill feed-forward pulse (17), the lower layer start-mill feed-forward pulse (18) and the lower layer stop-mill feed-forward pulse (19) in real time, converting the total start-mill feed-stop pulse into an ammonia gas regulating valve opening offset delta m after speed limiting calculation, and acting on a denitration system ammonia injection regulating valve (26) to participate in the control of the denitration system;
When the start-stop actions of different layers of grinding groups trigger the output of a start-stop feed-forward loop or a stop-grinding feed-forward loop, in the feed-forward duration time t, the total start-stop feed-forward pulse value is converted into an ammonia regulating valve opening bias delta m through speed limiting and amplitude limiting calculation according to the ammonia quantity feed-forward quantity change, the ammonia regulating valve opening bias delta m is overlapped to the denitration ammonia injection regulating valve to participate in the actual regulation of the denitration ammonia quantity, after the feed-forward duration time t is finished, the start-stop feed-forward quantity is limited to return to zero at a set speed limit, the opening of the ammonia injection regulating valve of the denitration system is gradually restored to a PID controller instruction (24), and the start-stop ammonia quantity feed-forward action flow of the unit grinding group is finished.
3. The control method according to claim 2, wherein the total start-stop feed-forward pulse value TF is expressed as:
TF＝F1st+F1sp+F2st+F2sp++F3st+F3sp
Wherein: f1st is the upper layer grinding starting feedforward pulse value; f1sp is the upper layer stop-milling feedforward pulse value; f2st is a middle layer grinding starting feedforward pulse value; f2sp is the middle layer stop-grinding feedforward pulse value; f3st is the lower layer grinding starting feedforward pulse value; f3sp is the lower stop-feed pulse value.
4. The control method according to claim 2, wherein the ammonia regulating valve opening bias Δm is calculated as:
Wherein: TF is the feedforward pulse value of total start-stop mill, and K is the linear function gain of flow and opening of the ammonia injection valve.
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| JP2002018234A (en) * | 2000-07-06 | 2002-01-22 | Babcock Hitachi Kk | Method and apparatus for controlling amount of injection of ammonia into denitrification apparatus for treating exhaust combustion gas of pulverized coal |
| CN112915741A (en) * | 2021-01-13 | 2021-06-08 | 中国大唐集团科学技术研究院有限公司火力发电技术研究院 | Denitration optimization method |
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| CN111111430B (en) * | 2019-12-19 | 2022-04-01 | 华电电力科学研究院有限公司 | SCR denitration regulation control method for urea pyrolysis furnace |
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| JP2002018234A (en) * | 2000-07-06 | 2002-01-22 | Babcock Hitachi Kk | Method and apparatus for controlling amount of injection of ammonia into denitrification apparatus for treating exhaust combustion gas of pulverized coal |
| CN112915741A (en) * | 2021-01-13 | 2021-06-08 | 中国大唐集团科学技术研究院有限公司火力发电技术研究院 | Denitration optimization method |
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