CN116300402A - Boiler denitration control system and method under flue gas bypass working condition of economizer - Google Patents
Boiler denitration control system and method under flue gas bypass working condition of economizer Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 239000003546 flue gas Substances 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 23
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 88
- 239000003245 coal Substances 0.000 claims abstract description 41
- 239000011159 matrix material Substances 0.000 claims abstract description 41
- 230000003044 adaptive effect Effects 0.000 claims abstract description 17
- 230000003321 amplification Effects 0.000 claims abstract description 13
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 13
- 230000000670 limiting effect Effects 0.000 claims description 30
- 238000010926 purge Methods 0.000 claims description 14
- 238000001514 detection method Methods 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 4
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- 238000003860 storage Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
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- 238000012827 research and development Methods 0.000 description 1
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- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
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Abstract
The invention provides a boiler denitration control system and a method under the flue gas bypass working condition of an economizer, which are used for calculating the deviation between nitrogen oxides at the outlet of a boiler and a set value; generating PID control parameters and deviation input amplification coefficients by utilizing the adaptive matrix according to the current state of the unit; amplifying the calculated deviation by using a deviation input amplification factor as a deviation input; calculating and generating a feedforward signal according to the nitrogen oxide content of the denitration inlet and differential signals thereof, unit load and the pre-starting quantity of the start-stop coal mill; based on the deviation input and the feedforward signal, generating a control output by using a PID control method under the PID control parameters; and generating different amplitude limits on control output according to the quality of the coal fed into the furnace and the start-stop coal mill. The invention can effectively reduce denitration control delay and improve control efficiency and adaptability.
Description
Technical Field
The invention belongs to the technical field of boiler denitration control, and relates to a boiler denitration control system and method under a flue gas bypass working condition of an economizer.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
One of the main difficulties in limiting the deep peak shaving of the thermal power generating unit at present is that the requirements of the flue gas temperature at the denitration inlet of the Selective Catalytic Reduction (SCR) are difficult to meet. The minimum operating temperature of the denitration catalyst is required to be more than 300 ℃, and below the temperature, the effect of the catalyst can be reduced, and adverse effects such as NH4HSO4 deposition of downstream equipment can be caused. When the unit depth peak regulation is carried out, the flue gas temperature of the SCR denitration inlet can be gradually reduced to be incapable of meeting the requirements along with the weakening of combustion, and the denitration system is withdrawn from operation, so that the emission of NOx gas exceeds the standard. One of the methods for solving the problem is to add a flue gas bypass of the economizer, and the baffle of the flue gas bypass of the economizer is closed under the high-load working condition of the boiler; under the low-load working condition of the boiler, when the temperature of the flue gas is lower than the lowest temperature of the catalyst, the bypass baffle is opened to enable the boiler flue gas to directly enter the SCR denitration device without being cooled by the economizer, so that sufficient high-temperature flue gas is obtained. The method can solve the problem that the SCR denitration device cannot be put into operation under low load, and has small project investment.
The inventor finds that the following defects exist in boiler denitration control under the flue gas bypass working condition of the economizer in the research and development and application processes:
the denitration control delay is high: the pure response time of the denitration control is more than 3 minutes, the total reaction time is about tens of minutes, and a large hysteresis control scheme must be designed for increasing the control to obtain good quality.
The original control scheme has the advantages of simple smoke bypass control, manual control, easy error, easy differential pressure deterioration of the air preheater and higher technical requirements on machine set operators.
The original control scheme has poor adaptability, and only static relation is considered, so that the denitration control quality is particularly poor when the unit load is frequently changed and the coal mill is started and stopped.
Disclosure of Invention
In order to solve the problems, the invention provides a boiler denitration control system and a method under the flue gas bypass working condition of an economizer.
According to some embodiments, the present invention employs the following technical solutions:
a boiler denitration control method under the flue gas bypass working condition of an economizer comprises the following steps:
calculating the deviation between the nitrogen oxides at the outlet of the boiler and a set value;
generating PID control parameters and deviation input amplification coefficients by utilizing the adaptive matrix according to the current state of the unit;
amplifying the calculated deviation by using a deviation input amplification factor as a deviation input;
calculating and generating a feedforward signal according to the nitrogen oxide content of the denitration inlet and differential signals thereof, unit load and the pre-starting quantity of the start-stop coal mill;
based on the deviation input and the feedforward signal, generating a control output by using a PID control method under the PID control parameters;
and generating different amplitude limits on control output according to the quality of the coal fed into the furnace and the start-stop coal mill.
An alternative embodiment further includes shutting down the control output in the presence of a nitrogen oxide detection system purge.
As an alternative embodiment, further comprising: the amplitude limitation control output is used as a tracking quantity.
As an alternative implementation mode, the specific process of generating the PID control parameters by using the adaptive matrix comprises the steps that the adaptive matrix selects load segment operation and coal quality entering the furnace according to the current unit load through a piecewise function, and corresponding proportional coefficient Kp, integral coefficient Ki and differential coefficient Kd are obtained after matrix operation and are used as the PID control parameters.
A boiler denitration control system under economizer flue gas bypass operating mode, includes:
the parameter self-adaptive calculation module is configured to generate PID control parameters and deviation input amplification coefficients by utilizing the self-adaptive matrix according to the current state of the unit;
a deviation generation circuit configured to calculate a deviation of the boiler outlet nitrogen oxides from the set value; amplifying the calculated deviation by using a deviation input amplification factor as a deviation input;
the feedforward generation loop is configured to calculate and generate a feedforward signal according to the content of nitrogen oxides in the denitration inlet and differential signals thereof, unit load and the pre-start quantity of the start-stop coal mill;
a PID controller configured to generate a control output using a PID control method under the PID control parameters based on the bias input, the feedforward signal;
and the amplitude limiting loop is configured to generate different amplitude limits on the control output according to the quality of the coal entering the furnace and the start-stop coal mill.
As an alternative embodiment, the deviation generating circuit is configured to calculate the deviation between the outlet oxynitride and the set value, and output the deviation to the deviation input pin of the PID controller E through the operation of the amplification coefficient of the adaptive matrix K and the deviation dead zone.
As an alternative implementation manner, the feedforward generation loop is configured to select the load section operation of the denitration inlet nitrogen oxide content, the denitration inlet nitrogen oxide derivative and the unit load through the piecewise function, start and stop the pre-start amount of the coal mill, and use the load section operation as the feedforward input of the PID controller through the adder operation, and when the numerical value changes, the feedforward generation loop directly acts on the output of the PID controller to play a role in pre-action, so that the hysteresis effect is counteracted and the control quality is improved.
As an alternative implementation mode, the amplitude limiting loop is configured to generate different amplitude limiting values through self-adaptive matrix operation according to different coal quality of the furnace and conditions of starting and stopping the coal mill, input the different amplitude limiting values into the amplitude limiting functional block, limit an output instruction of the PID, pause the PID operation when the PID output reaches the limiting value, and play a role in limiting output, preventing integral saturation and reducing disturbance when the nitrogen oxide value changes suddenly due to starting and stopping the coal mill.
The system also comprises a detection system purging locking loop, wherein when the detection system purging is performed, the output of the control system is kept at the current value by the switcher, the PID controller is switched to a tracking mode, the tracked value is an instruction of the current denitration control valve and plays a role of shielding, and when the purging is finished, the shielding is released, and the operation is recovered.
The method also comprises the step of outputting a pulse signal to the PID controller and the outlet switcher when the unit load is smaller than the minimum load, and directly outputting an instruction to the economizer smoke bypass baffle through the unit load by the operation of a pre-start fold line function, so as to play a role in pre-opening the bypass baffle to improve the denitration inlet temperature.
As an alternative embodiment, the device further comprises a denitration inlet temperature control loop, wherein the denitration inlet temperature control loop is configured to calculate the deviation between the denitration inlet temperature and a set value through a PID controller, and when the denitration inlet temperature is deviated from the set value, the PID controller outputs corresponding instructions to an economizer flue gas bypass baffle through parameter calculation of a proportional coefficient Kp, an integral coefficient Ki and a differential coefficient Kd, so that the deviation value between the denitration inlet temperature and the set value is reduced.
Compared with the prior art, the invention has the beneficial effects that:
(1) PID control adopting the parameter adaptive matrix has stronger adaptability and convergence, and can overcome the difficulty that the load in the denitration automatic control system suddenly changes and the coal quality changes to cause overrun of outlet nitrogen oxides.
(2) The adoption of the majority-value input feedforward can start the action of the pre-action, and can overcome the problems of poor control quality caused by large hysteresis and start-stop coal mill in the denitration control system.
(3) The PID controller of the parameter self-adaptive matrix has strong compatibility, can be realized by using a Distributed Control System (DCS) for almost all kinds of power plants, saves the cost of controlling equipment transformation and increasing peripheral equipment, and has low transformation cost.
(4) The amplitude limiting loop can limit output under different conditions, and has the functions of preventing integral saturation and reducing disturbance.
(5) The adopted detection system purging locking loop can avoid disturbance of a control system and enhance control quality under the condition of purging the system.
(6) The adopted self-adaptive loop of the flue gas bypass baffle of the economizer can carry out self-adaptive adjustment on the control loop according to the load of the unit and the differential pressure signal of the air preheater, the temperature set value of the denitration inlet is improved according to actual conditions, the flue gas bypass baffle of the economizer is started in advance, the failure of the denitration catalyst and the differential pressure deterioration of the air preheater are avoided, and the misoperation of operators of the unit is reduced.
In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
Fig. 1 is a structural diagram of denitration control according to an embodiment;
FIG. 2 is a block diagram of an example two economizer flue gas bypass baffle control;
wherein, 1, PID controller block, 2, first adaptive matrix block, 3, adder block, 4, deviation dead zone calculating block, 5, amplitude limiting block, 6, switcher block, 7, first fold line function block, 8, second fold line function block, 9, third fold line function block, 10, fourth, 11, fifth, 12, sixth, 13, seventh, 14, multiplier, 15, second adaptive matrix, 16, eighth;
1-1 parts of PID controller blocks, 1-2 parts of dual-input switcher blocks, 1-3 parts of deviation dead zone calculation blocks, 1-4 parts of broken line function blocks, 1-5 parts of comparator blocks, 1-6 parts of pulse trigger blocks, 1-7 parts of subtracter blocks, 1-8 parts of adder blocks, 1-9 parts of self-adaptive matrix blocks.
Detailed Description
The invention will be further described with reference to the drawings and examples.
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Example 1
Fig. 1 is a block diagram of automatic denitration control according to the present embodiment. As shown in FIG. 1, the denitration control system comprises a boiler outlet nitrogen oxide and set value deviation generation loop, a parameter self-adaptive matrix, a feedforward generation loop, an amplitude limiting loop and a detection system purging locking loop.
Specifically, the boiler outlet nox and setpoint bias generation circuit includes an outlet nox and setpoint bias signal, a multiplication block 14, and a bias dead block 4.
The deviation of the outlet nitrogen oxide and the set value is connected to the multiplication block 14 to multiply the K coefficient output by the adaptive matrix, the other end of the deviation dead block 4 is connected to the deviation input end E of the PID controller, and the other end of the deviation dead block 4 is connected to the deviation input end E of the PID controller to serve as the deviation input of the PID controller.
The parameter self-adaptive matrix loop comprises a unit load signal, a coal quality signal, a first folding line function block 7, a self-adaptive matrix block 2, a second folding line function block 8, a third folding line function block 9 and a fourth folding line function block 10.
The coal quality signal of entering the furnace is connected to the input end of the self-adaptive matrix block 2, the unit load signal is connected to the input end of the first folding line function block 7, the other end of the first folding line function block 7 is connected to the input end of the self-adaptive matrix block 2, the output end of the self-adaptive matrix block 2 is respectively connected with the input ends of the second folding line function block 8, the third folding line function block 9 and the fourth folding line function block 10, and the output ends of the second folding line function block 8, the third folding line function block 9 and the fourth folding line function block 10 respectively output Kp proportionality coefficient, ki integration coefficient and Kd differential coefficient to the PID controller as adjusting parameters of the PID controller.
The specific feedforward generation loop comprises a denitration inlet nitrogen oxide content signal, a denitration inlet nitrogen oxide differential signal, a unit load signal, a start-stop coal mill pre-start signal, an adder block 3, a fifth folding line function block 11 and a sixth folding line function block 12.
The denitration inlet nitrogen oxide content signal, the denitration inlet nitrogen oxide differential signal and the unit load signal are connected to the input end of the adder block 3, the unit load signal is connected to the input end of the fifth folding line function block 11, the output end of the fifth folding line function block 11 is connected to the input end of the adder block 3, and the start-stop coal mill pre-start signal is generated; is connected to the input of a sixth folding line function block 12, the output of said sixth folding line function block 12 is connected to the input of an adder block 3, and the output of said adder block 3 is connected to the feedforward FF terminal of the PID control block 1.
The specific amplitude limiting loop comprises a coal quality signal of the furnace, a start-stop coal mill signal, a second adaptive matrix block 15, a seventh folding line block 13 and an eighth folding line block 16.
The coal quality signal of entering the furnace, start-stop coal mill signal connect to the input of the self-adaptation matrix block 15, the output of self-adaptation matrix block 15 connect to the input of seventh dog-ear 13, eighth dog-ear 16 respectively, the output of seventh dog-ear 13 connect to the high-limit H end of amplitude limiting block 5, the output of eighth dog-ear 16 connect to the low-limit L end of amplitude limiting block 5, the S input of amplitude limiting block 5 connect to the OUT output of PID controller, the output of amplitude limiting block 5 connect to the K2 input of switcher module 6 to the output signal suspends PID controller operation when the high-low limit of amplitude limiting block 5 moves.
The particular detection system purge lockout circuit includes a nitrogen oxide measurement device purge signal, a switch block 6.
The purging signal of the nitrogen oxide measuring device is respectively connected to the TS tracking switching signal of the PID control module and the SW switching input end of the switcher block 6, the input ends k1 and k2 of the switcher block 6 are respectively connected to the output end of the switcher block 6 and the output end of the amplitude limiting block 5, and the output end of the switcher block 6 is simultaneously connected to the S tracking measuring end of the PID control block 1 and the input end k1 of the switcher block 6.
The deviation between the nitrogen oxide at the outlet of the embodiment and a set value is outputted to a deviation input pin of the PID controller E through the operation of an amplification coefficient of the adaptive matrix K and a deviation dead zone, and is used as a deviation input signal of the PID controller. The unit load is subjected to piecewise function selection load section operation and coal quality entering the furnace, and then corresponding proportional coefficient Kp, integral coefficient Ki and differential coefficient Kd are obtained after matrix operation and are used as control parameters of a PID controller. The content of nitrogen oxides in the denitration inlet, the nitrogen oxide differentiation of the denitration inlet and the unit load are calculated by selecting a load section through a piecewise function, and the pre-starting quantity of the coal mill is started and stopped and is calculated through an adder to serve as the feedforward input of the PID controller. The coal quality of the entering furnace and the signal of the start-stop coal mill are subjected to self-adaptive matrix operation to generate different amplitude limiting values, the amplitude limiting values are input into the limiting functional block, the output instruction of the PID is limited, and the PID operation is suspended when the PID output reaches the limiting value. When the purging signal of the measuring device is triggered, the output of the control system is kept at the current value by the switcher, the PID controller is switched to a tracking mode, the tracked value is the instruction of the current denitration control valve, and the shielding effect is achieved.
Example two
Fig. 2 is a block diagram of the economizer flue gas bypass control according to the present embodiment. As shown in fig. 2, the economizer flue gas bypass control system comprises a denitration inlet temperature deviation generating loop and a set value deviation generating loop, an economizer flue gas bypass baffle self-adaptive loop and a denitration inlet temperature PID control loop.
The specific denitration inlet temperature and set value deviation generating circuit comprises a denitration inlet temperature and denitration inlet temperature set value number, a deviation dead block 3, a subtracter block 7 and an adder block 8.
The denitration inlet temperature and the set value deviation signal are connected to the deviation dead block 3 input signal, and the deviation dead block 3 output signal is connected to the deviation input end E of the PID controller 1.
The economizer flue gas bypass baffle self-adaptive loop comprises a unit load signal, a minimum load signal, an air preheater differential pressure signal, a self-adaptive matrix 9, a broken line function block 4, a comparator block 5, a pulser block 6 and a switcher block 2.
The unit load signal is connected to the input end of the self-adaptive matrix block 9 and the input end 1 of the comparator block 5 respectively, the differential pressure signal of the air preheater is connected to the input end of the self-adaptive matrix block 9, the output end of the self-adaptive matrix is output to the input ends of the subtracter block 8 and the broken line function block 4 respectively, the output end of the broken line function block 4 is connected to the input end K1 of the switcher block 2, the minimum load signal is connected to the input end 2 of the comparator block 5, and the output end of the comparator block 5 is connected to the input end of the pulser block 6. The output end of the pulser block 6 is respectively connected to the tracking switching TS end of the PID controller 1 and the switch block 2Sw end, and the output end of the switch block 2 is connected to the tracking quantity S end of the PID controller block and simultaneously outputs a command to the bypass baffle of the economizer.
The denitration inlet temperature PID control loop comprises a PID controller 1, receives a denitration inlet temperature and set value deviation signal, carries out PID adjustment according to a fixed Kp proportional coefficient, a fixed Ki integral coefficient and a fixed Kd differential coefficient, and outputs the PID adjustment to a flue gas bypass baffle instruction.
The denitration inlet temperature and the set value deviation are output to a deviation input pin of a PID controller E through deviation dead zone operation, differential pressure signals of the air preheater are input to an adaptive matrix 9, when differential pressure of the air preheater is overlarge, the adaptive matrix is output to an adder block 8, when unit load is smaller than minimum load, a pulse signal is output to the PID controller and an outlet switcher, and the unit load is directly output to an economizer flue gas bypass baffle instruction through pre-start fold line function operation, so that the effect of pre-starting a bypass baffle to improve the denitration inlet temperature is achieved. When the denitration inlet temperature deviates from the set value, the PID controller outputs corresponding instructions to the flue gas bypass baffle of the economizer through parameter operation such as a proportional coefficient Kp, an integral coefficient Ki, a differential coefficient Kd and the like, so that the denitration inlet temperature and the set value deviation value are reduced.
From the above description, it can be seen that the above embodiments achieve the following technical effects:
(1) The PID control of the self-adaptive matrix adjusting parameters has stronger self-adaptability and convergence, and can overcome the difficulty of overrun of outlet nitrogen oxides caused by abrupt load change and coal quality change in a denitration automatic control system.
(2) The multi-numerical-value input feedforward can start the action of the pre-action, and can overcome the difficulty of poor control quality caused by large hysteresis and start-stop of the coal mill in the denitration control system.
(3) The amplitude limiting loop of the self-adaptive adjusting matrix is applied, so that output can be limited under different conditions, and the effects of preventing integral saturation and reducing disturbance are achieved.
(4) The adopted detection system purging locking loop can avoid disturbance of a control system and enhance control quality under the condition of purging the system.
(5) The adopted self-adaptive loop of the flue gas bypass baffle of the economizer can carry out self-adaptive adjustment on the control loop according to the load of the unit and the differential pressure signal of the air preheater, the temperature set value of the denitration inlet is improved according to actual conditions, the flue gas bypass baffle of the economizer is started in advance, the failure of the denitration catalyst and the differential pressure deterioration of the air preheater are avoided, and the misoperation of operators of the unit is reduced.
The above-described embodiments are merely examples.
In other embodiments, each execution module or its parameter setting range may be replaced as long as the above-described functions can be implemented. Not limited to the above examples.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (10)
1. The boiler denitration control method under the flue gas bypass working condition of the economizer is characterized by comprising the following steps of:
calculating the deviation between the nitrogen oxides at the outlet of the boiler and a set value;
generating PID control parameters and deviation input amplification coefficients by utilizing the adaptive matrix according to the current state of the unit;
amplifying the calculated deviation by using a deviation input amplification factor as a deviation input;
calculating and generating a feedforward signal according to the nitrogen oxide content of the denitration inlet and differential signals thereof, unit load and the pre-starting quantity of the start-stop coal mill;
based on the deviation input and the feedforward signal, generating a control output by using a PID control method under the PID control parameters;
and generating different amplitude limits on control output according to the quality of the coal fed into the furnace and the start-stop coal mill.
2. The method for controlling denitration of a boiler under a flue gas bypass condition of an economizer according to claim 1, further comprising: the amplitude limitation control output is used as a tracking quantity.
3. The boiler denitration control method under the flue gas bypass working condition of the economizer according to claim 1, wherein the specific process of generating PID control parameters by utilizing the adaptive matrix comprises the steps that the adaptive matrix selects load segment operation and coal quality entering the boiler according to the current unit load through a piecewise function, and the corresponding proportional coefficient Kp, integral coefficient Ki and differential coefficient Kd are obtained after matrix operation and are used as the PID control parameters.
4. The utility model provides a boiler denitration control system under economizer flue gas bypass operating mode which characterized in that includes:
the parameter self-adaptive calculation module is configured to generate PID control parameters and deviation input amplification coefficients by utilizing the self-adaptive matrix according to the current state of the unit;
a deviation generation circuit configured to calculate a deviation of the boiler outlet nitrogen oxides from the set value; amplifying the calculated deviation by using a deviation input amplification factor as a deviation input;
the feedforward generation loop is configured to calculate and generate a feedforward signal according to the content of nitrogen oxides in the denitration inlet and differential signals thereof, unit load and the pre-start quantity of the start-stop coal mill;
a PID controller configured to generate a control output using a PID control method under the PID control parameters based on the bias input, the feedforward signal;
and the amplitude limiting loop is configured to generate different amplitude limits on the control output according to the quality of the coal entering the furnace and the start-stop coal mill.
5. The boiler denitration control system under the flue gas bypass working condition of the economizer according to claim 4, wherein the deviation generating loop is configured to calculate deviation between the outlet nitrogen oxide and a set value, and output the deviation to a deviation input pin of the PID controller E through the operation of an amplification coefficient of the adaptive matrix K and a deviation dead zone.
6. The boiler denitration control system under the flue gas bypass working condition of an economizer according to claim 4, wherein the feedforward generation loop is configured to select load segment operation by a piecewise function on the content of nitrogen oxides at a denitration inlet, the differential of nitrogen oxides at the denitration inlet and the load of a unit, start and stop the pre-start quantity of a coal mill, and the pre-start quantity is used as feedforward input of a PID controller through adder operation, and is directly applied to the output of the PID controller when the numerical value changes.
7. The boiler denitration control system under the flue gas bypass working condition of the economizer as claimed in claim 4, wherein the amplitude limiting loop is configured to generate different amplitude limiting values through self-adaptive matrix operation according to different coal quality of the entering furnace and conditions of starting and stopping a coal mill, input the different amplitude limiting values into the amplitude limiting functional block, limit an output instruction of the PID controller and pause PID operation when the output of the PID controller reaches the limiting value.
8. The boiler denitration control system under flue gas bypass operation of an economizer as recited in claim 4, further comprising a detection system purge lockout circuit configured such that when the detection system is purged, the output of the control system is maintained at a current value by the switch, the PID controller switches to a tracking mode, and the tracked value is an instruction of the current denitration control valve.
9. The boiler denitration control system under the flue gas bypass working condition of an economizer according to claim 4, further comprising a flue gas bypass baffle pre-starting loop of the economizer, wherein the flue gas bypass baffle pre-starting loop is configured to output a pulse signal to the PID controller and the outlet switcher when the unit load is smaller than the minimum load, and directly output a flue gas bypass baffle command of the economizer through the unit load through the pre-starting broken line function operation.
10. The boiler denitration control system under the flue gas bypass working condition of the economizer as claimed in claim 4, further comprising a denitration inlet temperature control loop, wherein the denitration inlet temperature control loop is configured to operate by a PID controller, and when the denitration inlet temperature deviates from a set value, the PID controller outputs corresponding instructions to the flue gas bypass baffle of the economizer by operating parameters of a proportional coefficient Kp, an integral coefficient Ki and a differential coefficient Kd.
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