CN109603525B - Denitration partition ammonia spraying control method based on non-uniformity judgment - Google Patents
Denitration partition ammonia spraying control method based on non-uniformity judgment Download PDFInfo
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 282
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 140
- 238000005507 spraying Methods 0.000 title claims abstract description 85
- 238000005192 partition Methods 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 21
- 230000001105 regulatory effect Effects 0.000 claims abstract description 47
- 238000002347 injection Methods 0.000 claims abstract description 33
- 239000007924 injection Substances 0.000 claims abstract description 33
- 238000005070 sampling Methods 0.000 claims abstract description 15
- 239000000779 smoke Substances 0.000 claims abstract description 12
- 238000009826 distribution Methods 0.000 claims abstract description 10
- 238000004364 calculation method Methods 0.000 claims description 27
- 239000003245 coal Substances 0.000 claims description 23
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 12
- 108700041286 delta Proteins 0.000 claims description 12
- 239000001301 oxygen Substances 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- 238000004458 analytical method Methods 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000013507 mapping Methods 0.000 claims description 6
- 238000002485 combustion reaction Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 5
- 238000010248 power generation Methods 0.000 abstract description 3
- 238000009827 uniform distribution Methods 0.000 abstract description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 10
- 239000003546 flue gas Substances 0.000 description 10
- 239000003054 catalyst Substances 0.000 description 3
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8631—Processes characterised by a specific device
-
- 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
- B01D53/8696—Controlling the catalytic process
Abstract
The invention relates to automatic control in the technical field of coal-fired power generation, in particular to a denitration partition ammonia spraying control method based on non-uniformity judgment. The existing automatic denitration zone ammonia injection control cannot meet the real-time automatic regulation requirement of an ammonia injection regulating valve, delay and hysteresis exist in ammonia injection quantity control, the ammonia injection quantity and NOx concentration are not well matched, and the NOx control effect at the outlet of the reactor is poor. The invention provides a denitration partition ammonia spraying control method based on non-uniformity judgment, which comprises the steps of dividing a plurality of ammonia spraying partitions according to the concentration level of NOx at an outlet of an SCR reactor according to trends, sampling smoke at an extending position corresponding to each ammonia spraying partition in a flue, calculating non-uniformity CV of the concentration of NOx at a sampling section of the flue, combining the size of the ammonia spraying amount and the concentration distribution of the NOx at each area, accurately adjusting a partition ammonia spraying regulating valve and an ammonia spraying branch regulating valve according to different conditions, and meeting the matching requirements of the ammonia spraying amount and the concentration of the NOx, thereby realizing the accurate control and uniform distribution of the NOx at the outlet of the SCR denitration reactor in real time, quickly, stably and effectively.
Description
Technical Field
The invention relates to automatic control in the technical field of coal-fired power generation, in particular to a denitration partition ammonia spraying control method based on non-uniformity judgment.
Background
Most of thermal power plants for coal-fired power generation in China adopt a Selective Catalytic Reduction (SCR) denitration technology to treat NOx pollutants. The core equipment of the SCR denitration technology is an SCR reactor, and as shown in fig. 1, the technological process of the SCR denitration reaction is as follows: the raw flue gas from the economizer is firstly mixed with diluted ammonia gas at a zoned ammonia spraying grid, the ammonia spraying grid consists of a plurality of evenly arranged nozzles (see figure 2), each ammonia spraying branch is provided with a manual butterfly valve to adjust the ammonia spraying amount of one zone, the mixed flue gas vertically passes through an SCR reactor, two or three layers of catalysts are arranged in the reactor, the mixed ammonia-containing flue gas is contacted with the surface of the catalyst, and NOx and NH are contacted with each other 3 Reduction reaction takes place on the surface of the catalyst to produce N which is harmless to the environment 2 And water, thus achieve the goal of removing NOx in the flue gas, therefore the concentration distribution uniformity of NOx in the original flue gas is very important to the denitration reaction under the aforesaid ammonia injection grid configuration mode, once the valve opening size of the ammonia injection grid valve station of the existing ammonia injection control system is adjusted, the ammonia injection grid valve station is not adjusted in the subsequent operation. In the denitration reaction, ammonia gas supplied by an ammonia zone is firstly mixed with dilution air sent by a dilution fan, then is uniformly sprayed into a flue to be mixed with raw flue gas after passing through a manual butterfly valve on an ammonia spraying branch. The ammonia injection amount on the ammonia supply main pipe is automatically adjusted according to the unit load, the original flue gas NOx concentration value and the denitration efficiency to be achieved, when the denitration efficiency requirement is higher, the ammonia injection amount is increased, and when the denitration requirement is lower, the ammonia injection amount is reduced; when the load is fixed, the running state of the denitration reactor depends on the fixed ammonia injection under a certain working conditionThe amount is uniformly and reasonably distributed on the spraying section, and under ideal conditions, the original flue gas NOx is uniformly distributed and the flow velocity is uniform, only ammonia is required to be uniformly sprayed on the section, and the state of each manual butterfly valve on the ammonia spraying branch is not required to be adjusted, so that the method is also adopted by the existing denitration system of all coal-fired units.
In actual operation, due to poor uniformity of NOx distribution in raw flue gas, especially the NOx distribution rule of the raw flue gas of a boiler in a butt-fired mode can be changed greatly in the coal mill switching process and after the coal mill switching process, especially after the coal mill switching process or the load change, the opening of a manual butterfly valve of each ammonia spraying branch is not adjusted, so that the ammonia spraying amount of each region of a flue in actual operation is not matched with the actual concentration distribution of NOx, and further, the problems of large deviation between a NOx concentration monitoring value of a denitration outlet and a concentration monitoring value on a chimney, increased ammonia escape amount in operation, equipment blockage of an air preheater and the like, increased unit consumption of a fan, reduced unit output and the like are caused. The invention application No. 2016106049468 discloses a denitration refinement control method suitable for a hedging type coal-fired boiler, which can change the quick adjustment of the opening of an ammonia supply branch regulating valve according to the load and the running state change of a coal mill, but the control still can not meet the real-time control of an ammonia injection regulating valve; and because of the hysteresis of the NOx concentration measurement at the inlet and outlet of the SCR denitration reactor and the self characteristics of a control system, the ammonia injection amount control process of the denitration system becomes a large delay link, so that the automatic control is difficult to obtain the expected good effect, and particularly the matching effect of the ammonia injection amount and the NOx concentration is poor. In addition, the load fluctuation of the unit and the start-stop switching of the coal mill have large fluctuation amplitude and high fluctuation speed of the NOx at the inlet of the reactor, and the control effect of the NOx at the outlet of the reactor can be seriously influenced.
Disclosure of Invention
The invention aims to solve the technical problems and the technical task of solving the problems that the existing automatic denitration partition ammonia injection control cannot meet the real-time automatic adjustment of an ammonia injection regulating valve and obvious delay exists in ammonia injection quantity control, so that the ammonia injection quantity and NOx concentration are not well matched, the NOx control effect at the outlet of a reactor is poor, and the like.
The invention solves the technical problems by adopting the technical scheme that: a denitration partition ammonia spraying control method based on non-uniformity judgment comprises the following steps in sequence:
(1) Setting an electric regulating valve with an automatic regulating function as an ammonia spraying branch regulating valve in each ammonia spraying branch;
(2) Confirming the position of a partition corresponding to an ammonia spraying grid with an ammonia spraying section, making a fixed number on a region corresponding to each ammonia spraying branch, defining the opening of a valve with n ammonia spraying branches as Y= (Y11, Y12, Y13, Y21, Y22, Y23 … yij … yhm), yij being the opening of a corresponding regulating valve of the j-th ammonia spraying branch of the i-th group, wherein the valve of each three ammonia spraying branches is a group, and j and m are 1,2,3 and n are integer multiples of 3;
(3) Dividing a plurality of ammonia spraying subareas according to the concentration level of NOx at an outlet of the SCR reactor and trends, uniformly distributing the subareas according to the number of ammonia spraying branches, and arranging a subarea ammonia supply regulating valve in each ammonia spraying subarea;
(4) Carrying out fixed numbering on each partition coefficient amplifying module in the partition ammonia spraying control system, and defining the proportionality coefficient K of each coefficient amplifying module as K= (K1, K2, K3 … … kM), wherein M is the ammonia spraying partition number;
(5) Assuming that a certain boiler with opposite combustion has 5 coal mills, namely, a mill, B mill, C mill, D mill and E mill, defining an operation signal of the coal mill of the boiler and a load W of a unit as a variable X, wherein the load is divided into two load sections W1 and W2 in combination with actual conditions, and when the unit keeps at least 3 coal mills running above the minimum technical output, the operation combination working conditions of the coal mills are discretized as follows:
from this, the vector can be obtained:
X=（X1，X2，X3···Xn）；
(6) Under the operation condition of each coal mill, manually adjusting the ammonia supply quantity of each ammonia injection branch according to an ammonia injection grid adjusting method to ensure that the NOx concentration distribution of the cross section of the denitration outlet is uniform, and obtaining the functional relation among the opening Y of the ammonia supply branch valve, the scaling factor K of the coefficient amplifying module and the operation combination condition X of the coal mill:
Y＝F（X），K＝G（X）；
(7) The opening of the motor adjusting partition ammonia supply regulating valve or the ammonia spraying branch regulating valve is circularly calculated and adjusted through the following control steps;
(71) At the setting step, a set value of the NOx concentration of 273.15K and 1.013X10 at the outlet is given 5 The conversion value of the NOx concentration when the oxygen content is 6% under the Pa condition is entered into a timing module;
(72) Setting a Y pulse signal in a timing step through a set time, and entering a non-uniformity judging module; otherwise, the N signal is always given, the unevenness judging module is skipped, and the first to fourth deviation calculating modules are directly entered;
(73) When the timing module gives a Y signal, the system enters an unevenness judging module; at the unevenness judging module, receiving the CV signals transmitted by the calculating module, judging whether the CV signals are less than or equal to 15 percent, and entering the first to fourth deviation calculating modules if the CV signals are Y; otherwise 'N' and rapidly adjusting an ammonia injection branch regulating valve through mapping F (X);
(74) At the first to fourth deviation calculation modules, PVn output from the calculation module is input, respectively, where n=1, 2,3, 4 and the NOx set value given in the setting step; respectively calculating to obtain deviations delta 1, delta 2, delta 3 and delta 4, and correspondingly entering a first coefficient amplifying module to a fourth coefficient amplifying module;
(75) In the first to fourth coefficient amplifying modules, corresponding to K determined by the input mapping G (X) and delta obtained in the step (74), wherein K is K1, K2, K3 and K4 respectively, delta is delta 1, delta 2, delta 3 and delta 4 respectively, proportion calculation is carried out in the four coefficient amplifying modules, and K1 delta 1, K2 delta 2, K3 delta 3 and K4 delta 4 respectively enter four PID control modules;
(76) The inputs of each PID control module are k1 delta 1, k2 delta 2, k3 delta 3, k4 delta 4 and zero respectively, so that the opening degree of the partition ammonia supply regulating valve is regulated by regulating the motor;
(77) Sampling smoke corresponding to the extending positions of the ammonia spraying partitions on a flue after the denitration reactor, outputting the smoke to a sample acquisition and analysis module, and acquiring the smoke in real time and analyzing to obtain the concentration Cs of NOx and the oxygen content O of the NOx 2 The percent, the temperature Ts and the moisture content Xs are transmitted to a calculation module for calculation;
(78) In the calculation module, the original data obtained by sampling analysis is calculated to 273.15K and 1.013X10 by the following formulas 5 The calculated value Csn of the oxygen amount of NOx when the oxygen amount is 6% under the Pa condition, and the corresponding NOx concentration PVn (n=1, 2, 3. I. N) of each partition, the average value PV of the NOx concentration of the whole section and the non-uniformity CV of the NOx concentration of the sampling section are obtained through calculation of a partition ammonia injection control system;
in the i-th partition:
the SP is a set value of the concentration of NOx at the outlet of the reactor; CV,%; PV, mg/Nm 3 ；
(79) And the PVn, the PV and the CV obtained by the calculation module are transmitted to an upper computer, wherein the PVn is divided into one path to the first to fourth deviation calculation modules, and the CV is divided into one path to the unevenness judgment module.
The invention provides a denitration zone ammonia spraying control method based on non-uniformity judgment, which comprises the steps of dividing a plurality of ammonia spraying zones according to the concentration level of NOx at an outlet of an SCR reactor, sampling smoke at an extending position corresponding to each ammonia spraying zone in a flue, calculating the non-uniformity CV of the concentration of NOx at a sampling section of the flue, combining the size of ammonia spraying quantity and the concentration distribution of NOx at each zone, accurately adjusting a zone ammonia spraying regulating valve and an ammonia spraying branch regulating valve according to different conditions, meeting the matching requirement of the ammonia spraying quantity and the concentration of NOx, realizing the accurate control and uniform distribution of the NOx at the outlet of the SCR denitration reactor in real time, quickly, stably and effectively, specifically, referring to the prior invention application for quickly adjusting the ammonia spraying branch regulating valve when the non-uniformity CV is 15% as a critical point and adjusting the zone ammonia supplying regulating valve when the non-uniformity CV is more than 15%.
Drawings
Fig. 1: the invention provides a schematic diagram for partitioning and finely adjusting a denitration ammonia injection grid.
Fig. 2: the control method is a flow chart.
Fig. 3: the invention is schematically used in an SCR reactor.
Detailed Description
The invention is further described with reference to the accompanying drawings and detailed description.
As shown in fig. 1 to 3, a denitration partition ammonia injection control method based on non-uniformity judgment includes the following steps sequentially performed:
(1) Setting an electric regulating valve with an automatic regulating function as an ammonia spraying branch regulating valve in each ammonia spraying branch;
(2) Confirming the position of a partition corresponding to an ammonia spraying grid with an ammonia spraying section, making a fixed number on a region corresponding to each ammonia spraying branch, defining the opening of a valve with n ammonia spraying branches as Y= (Y11, Y12, Y13, Y21, Y22, Y23 … yij … yhm), wherein yij is the opening of a corresponding regulating valve of the j-th ammonia spraying branch of the i-th group, the valves of each three ammonia spraying branches are in one group, and j and m are 1,2 and 3; in fig. 1, only 24 ammonia spraying branches are drawn, and the actual SCR denitration reactor generally has 20-40 branches according to the capacity of the unit, which is not drawn one by one for simplicity in this embodiment;
(3) Dividing a plurality of ammonia spraying subareas according to the concentration level of NOx at an outlet of the SCR reactor according to trend, uniformly distributing the subareas according to the number of ammonia spraying branches, and arranging a subarea ammonia supply regulating valve for each ammonia spraying subarea, wherein in the embodiment, the subareas are divided into 4 ammonia spraying subareas shown in fig. 1 for simplicity;
(4) Carrying out fixed numbering on each partition coefficient amplifying module in the partition ammonia spraying control system, and defining the proportionality coefficient K of each coefficient amplifying module as K= (K1, K2, K3 … … kM), wherein M is the ammonia spraying partition number;
(5) Assuming that a certain boiler with opposite combustion has 5 coal mills, namely, a mill, B mill, C mill, D mill and E mill, defining an operation signal of the coal mill of the boiler and a load W of a unit as a variable X, wherein the load is divided into two load sections W1 and W2 in combination with actual conditions, and when the unit keeps at least 3 coal mills running above the minimum technical output, the operation combination working conditions of the coal mills are discretized as follows:
from this, the vector can be obtained:
X=（X1，X2，X3···Xn）；
(6) Under the operation condition of each coal mill, manually adjusting the ammonia supply quantity of each ammonia injection branch according to an ammonia injection grid adjusting method to ensure that the NOx concentration distribution of the cross section of the denitration outlet is uniform, and obtaining the functional relation among the opening Y of the ammonia supply branch valve, the scaling factor K of the coefficient amplifying module and the operation combination condition X of the coal mill:
Y＝F（X），K＝G（X）；
(7) The opening of the motor adjusting partition ammonia supply regulating valve or the ammonia spraying branch regulating valve is circularly calculated and adjusted through the following control steps;
(71) At the setting step, the outlet N is givenSetting value of Ox concentration, the NOx concentration is 273.15K, 1.013X10 5 The conversion value of the NOx concentration when the oxygen content is 6% under the Pa condition is entered into a timing module;
(72) Setting a Y pulse signal in a timing step through a set time, and entering a non-uniformity judging module; otherwise, the N signal is always given, the unevenness judging module is skipped, and the first to fourth deviation calculating modules are directly entered;
(73) When the timing module gives a Y signal, the system enters an unevenness judging module; at the unevenness judging module, receiving the CV signals transmitted by the calculating module, judging whether the CV signals are less than or equal to 15 percent, and entering the first to fourth deviation calculating modules if the CV signals are Y; otherwise 'N' and rapidly adjusting an ammonia injection branch regulating valve through mapping F (X);
(74) At the first to fourth deviation calculation modules, PVn output from the calculation module is input, respectively, where n=1, 2,3, 4 and the NOx set value given in the setting step; respectively calculating to obtain deviations delta 1, delta 2, delta 3 and delta 4, and correspondingly entering a first coefficient amplifying module to a fourth coefficient amplifying module;
(75) In the first to fourth coefficient amplifying modules, corresponding to K determined by the input mapping G (X) and delta obtained in the step (74), wherein K is K1, K2, K3 and K4 respectively, delta is delta 1, delta 2, delta 3 and delta 4 respectively, proportion calculation is carried out in the four coefficient amplifying modules, and K1 delta 1, K2 delta 2, K3 delta 3 and K4 delta 4 respectively enter four PID control modules;
(76) The inputs of each PID control module are k1 delta 1, k2 delta 2, k3 delta 3, k4 delta 4 and zero respectively, so that the opening degree of the partition ammonia supply regulating valve is regulated by regulating the motor;
(77) Sampling smoke corresponding to the extending positions of the ammonia spraying partitions on a flue after the denitration reactor, outputting the smoke to a sample acquisition and analysis module, and acquiring the smoke in real time and analyzing to obtain the concentration Cs of NOx and the oxygen content O of the NOx 2 The percent, the temperature Ts and the moisture content Xs are transmitted to a calculation module for calculation;
(78) In the calculation module, the original data obtained by sampling analysis is passed through273.15K, 1.013X10 were calculated by the following formula 5 The calculated value Csn of the oxygen amount of NOx when the oxygen amount is 6% under the Pa condition, and the corresponding NOx concentration PVn (n=1, 2, 3. I. N) of each partition, the average value PV of the NOx concentration of the whole section and the non-uniformity CV of the NOx concentration of the sampling section are obtained through calculation of a partition ammonia injection control system;
in the i-th partition:
the SP is a set value of the concentration of NOx at the outlet of the reactor; CV,%; PV, mg/Nm 3 ；
(79) And the PVn, the PV and the CV obtained by the calculation module are transmitted to an upper computer, wherein the PVn is divided into one path to the first to fourth deviation calculation modules, and the CV is divided into one path to the unevenness judgment module.
The invention provides a denitration zone ammonia spraying control method based on non-uniformity judgment, which comprises the steps of dividing a plurality of ammonia spraying zones according to the concentration level of NOx at an outlet of an SCR reactor, sampling smoke at an extending position corresponding to each ammonia spraying zone in a flue, calculating the non-uniformity CV of the concentration of NOx at a sampling section of the flue, combining the size of ammonia spraying quantity and the concentration distribution of NOx at each zone, accurately adjusting a zone ammonia spraying regulating valve and an ammonia spraying branch regulating valve according to different conditions, meeting the matching requirement of the ammonia spraying quantity and the concentration of NOx, realizing the accurate control and uniform distribution of the NOx at the outlet of the SCR denitration reactor in real time, quickly, stably and effectively, specifically, referring to the prior invention application for quickly adjusting the ammonia spraying branch regulating valve when the non-uniformity CV is 15% as a critical point and adjusting the zone ammonia supplying regulating valve when the non-uniformity CV is more than 15%.
Claims (1)
1. A denitration partition ammonia spraying control method based on non-uniformity judgment comprises the following steps in sequence:
(1) Setting an electric regulating valve with an automatic regulating function as an ammonia spraying branch regulating valve in each ammonia spraying branch;
(2) Confirming the position of a partition corresponding to an ammonia spraying grid with an ammonia spraying section, making a fixed number on a region corresponding to each ammonia spraying branch, defining the opening of a valve with n ammonia spraying branches as Y= (Y11, Y12, Y13, Y21, Y22, Y23 … yij … yhm), yij being the opening of a corresponding regulating valve of the j-th ammonia spraying branch of the i-th group, wherein the valve of each three ammonia spraying branches is a group, and j and m are 1,2,3 and n are integer multiples of 3;
(3) Dividing a plurality of ammonia spraying subareas according to the concentration level of NOx at an outlet of the SCR reactor and trends, uniformly distributing the subareas according to the number of ammonia spraying branches, and arranging a subarea ammonia supply regulating valve in each ammonia spraying subarea;
(4) Carrying out fixed numbering on each partition coefficient amplifying module in the partition ammonia spraying control system, and defining the proportionality coefficient K of each coefficient amplifying module as K= (K1, K2, K3 … … kM), wherein M is the ammonia spraying partition number;
(5) Assuming that a certain boiler with opposite combustion has 5 coal mills, namely, a mill, B mill, C mill, D mill and E mill, defining an operation signal of the coal mill of the boiler and a load W of a unit as a variable X, wherein the load is divided into two load sections W1 and W2 in combination with actual conditions, and when the unit keeps at least 3 coal mills running above the minimum technical output, the operation combination working conditions of the coal mills are discretized as follows:
from this, the vector can be obtained:
X=（X1，X2，X3···Xn）；
(6) Under the operation condition of each coal mill, manually adjusting the ammonia supply quantity of each ammonia injection branch according to an ammonia injection grid adjusting method to ensure that the NOx concentration distribution of the cross section of the denitration outlet is uniform, and obtaining the functional relation among the opening Y of the ammonia supply branch valve, the scaling factor K of the coefficient amplifying module and the operation combination condition X of the coal mill:
Y＝F（X），K＝G（X）；
(7) The opening of the motor adjusting partition ammonia supply regulating valve or the ammonia spraying branch regulating valve is circularly calculated and adjusted through the following control steps;
(71) At the setting step, a set value SP of the NOx concentration of 273.15K, 1.013X10 is given 5 The conversion value of the NOx concentration when the oxygen content is 6% under the Pa condition is entered into a timing module;
(72) Setting a Y pulse signal in a timing step through a set time, and entering a non-uniformity judging module; otherwise, the N signal is always given, the unevenness judging module is skipped, and the first to fourth deviation calculating modules are directly entered;
(73) When the timing module gives a Y signal, the system enters an unevenness judging module; at the unevenness judging module, receiving the CV signals transmitted by the calculating module, judging whether the CV signals are less than or equal to 15 percent, and entering the first to fourth deviation calculating modules if the CV signals are Y; otherwise 'N' and rapidly adjusting an ammonia injection branch regulating valve through mapping F (X);
(74) At the first to fourth deviation calculation modules, PVn output from the calculation module is input, respectively, where n=1, 2,3, 4 and the NOx set value given in the setting step; respectively calculating to obtain deviations delta 1, delta 2, delta 3 and delta 4, and correspondingly entering a first coefficient amplifying module to a fourth coefficient amplifying module;
(75) In the first to fourth coefficient amplifying modules, corresponding to K determined by the input mapping G (X) and delta obtained in the step (74), wherein K is K1, K2, K3 and K4 respectively, delta is delta 1, delta 2, delta 3 and delta 4 respectively, proportion calculation is carried out in the four coefficient amplifying modules, and K1 delta 1, K2 delta 2, K3 delta 3 and K4 delta 4 respectively enter four PID control modules;
(76) The inputs of each PID control module are k1 delta 1, k2 delta 2, k3 delta 3, k4 delta 4 and zero respectively, so that the opening degree of the partition ammonia supply regulating valve is regulated by regulating the motor;
(77) Sampling smoke corresponding to the extending positions of the ammonia spraying partitions on a flue after the denitration reactor, outputting the smoke to a sample acquisition and analysis module, and acquiring the smoke in real time and analyzing to obtain the concentration Cs of NOx and the oxygen content O of the NOx 2 The percent, the temperature Ts and the moisture content Xs are transmitted to a calculation module for calculation;
(78) In the calculation module, the original data obtained by sampling analysis is calculated to 273.15K and 1.013X10 by the following formulas 5 The calculated value Csn of the oxygen amount of NOx when the oxygen amount is 6% under the Pa condition, and the corresponding NOx concentration PVn (n=1, 2, 3. I. N) of each partition, the average value PV of the NOx concentration of the whole section and the non-uniformity CV of the NOx concentration of the sampling section are obtained through calculation of a partition ammonia injection control system;
in the i-th partition:
CV，%；PV，mg/Nm 3 ；
(79) And the PVn, the PV and the CV obtained by the calculation module are transmitted to an upper computer, wherein the PVn is divided into one path to the first to fourth deviation calculation modules, and the CV is divided into one path to the unevenness judgment module.
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| CN110568129B (en) * | 2019-09-26 | 2024-03-12 | 国能龙源环保有限公司 | SCR denitration outlet mixing and zoning flue gas NOx concentration detection system and method thereof |
| CN111426796B (en) * | 2019-12-23 | 2021-06-15 | 国能龙源环保有限公司 | Detection method using gas measurement system |
| CN112717670A (en) * | 2020-12-18 | 2021-04-30 | 华能陇东能源有限责任公司 | Control device and control method for ammonia injection grid of denitration system |
| CN112669268B (en) * | 2020-12-21 | 2023-06-06 | 昆明理工大学 | Multiphase mixed concentration field distribution uniformity evaluation method, system and terminal |
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