CN112973400A - SCR system ammonia injection branch pipe control method based on flow velocity and NOx concentration monitoring - Google Patents

SCR system ammonia injection branch pipe control method based on flow velocity and NOx concentration monitoring Download PDF

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CN112973400A
CN112973400A CN202110212275.1A CN202110212275A CN112973400A CN 112973400 A CN112973400 A CN 112973400A CN 202110212275 A CN202110212275 A CN 202110212275A CN 112973400 A CN112973400 A CN 112973400A
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branch pipe
ammonia
area
inert
nox concentration
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CN112973400B (en
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沈德魁
刘国富
王�琦
罗开红
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Nanjing Aomaike Apparatus Automation Co ltd
Nanjing Boling Energy Conservation And Environmental Protection Research Institute Co ltd
Southeast University
Qilu University of Technology
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Nanjing Aomaike Apparatus Automation Co ltd
Nanjing Boling Energy Conservation And Environmental Protection Research Institute Co ltd
Southeast University
Qilu University of Technology
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    • 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
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    • 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
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Abstract

The invention discloses an SCR system ammonia injection branch pipe control method based on flow velocity and NOx concentration monitoring, which comprises the following steps: measuring the flow velocity and NOx concentration of each sub-area smoke in the flue grid area on line; determining flow velocity inertia factors of the subareas according to the measured flow velocity characteristics of the flue gas of each subarea in the grid area of the flue; determining NOx concentration inert factors of the sub-regions according to the measured NOx concentration characteristics of the smoke of each sub-region in the grid region of the flue; determining an inert region and a non-inert region of the NOx flux change based on the flow velocity inertia factor and the NOx concentration inertia factor; the opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed value; the opening degree of the ammonia injection branch pipe valve corresponding to the non-inert area is a change value, and the changed opening degree of the ammonia injection branch pipe valve is determined by the set fuzzy rule base. The method can realize the real-time matching optimization of the ammonia-smoke equivalence ratio in the SCR system, effectively improve the utilization rate of ammonia and reduce the ammonia escape.

Description

SCR system ammonia injection branch pipe control method based on flow velocity and NOx concentration monitoring
Technical Field
The invention relates to an automatic control method for an ammonia injection branch pipe of an SCR (selective catalytic reduction) system based on-line monitoring of flue gas flow velocity-NOx concentration, belonging to the technical field of thermal energy power engineering.
Background
The Selective Catalytic Reduction (SCR) technology is a mainstream application technology for flue gas denitration of large coal-fired equipment at present, and the quality of the operation performance of the SCR technology directly depends on the ammonia injection characteristic of an SCR system. The ammonia injection equipment of the SCR system relates to two aspects of ammonia injection total amount control and ammonia injection distribution control. With the advance of ultra-low emission modification of coal-fired equipment, the ammonia injection distribution control of the SCR system draws much attention in the industry, the traditional manually-controlled ammonia injection control method obviously cannot realize better ammonia nitrogen mixing equivalence ratio in the system, and the research focus of the industry on how to realize the accurate control of the ammonia injection branch pipe (ammonia injection distribution control equipment) of the SCR system is focused.
The method can be obtained by combining the reaction mechanism of the SCR system, and only when the amount of nitrogen oxides (NOx) in the flue gas is reasonably matched with the amount of the injected reducing agent (NH3), higher denitration efficiency can be realized, and larger ammonia escape cannot be caused; and the actual content of NOx in the flue gas is determined by the flow rate of the flue gas and the concentration of the NOx together. In general, there are three main categories of existing SCR system ammonia injection allocation control solutions, which can be specifically described as: 1) completely neglecting the fluctuation of the flue gas operation characteristics in the unit flue, roughly adopting a fixed and unchangeable ammonia spraying and ammonia spraying distribution mode (such as patent CN201810146615.3) according to a single data monitoring result, wherein the ammonia nitrogen mixing matching degree of the SCR system applied by the method is extremely poor and cannot adapt to the severe requirements of ultra-low emission reconstruction; 2) the method comprises the steps that flue gas operation characteristics in the SCR system under various working conditions are obtained in an off-line data monitoring mode, and then a corresponding dynamic ammonia spraying distribution control strategy (such as patent CN201610102338.7) is formulated, so that the ammonia nitrogen mixing matching degree in the SCR system is improved to a certain extent, but the problem of deviation of flue gas characteristic parameters along with the operation time is difficult to overcome, and the self-adaptive capacity of dynamic ammonia spraying logic is poor; 3) the method is characterized in that the online monitoring of the flue gas characteristic parameters is realized on the section of an outlet flue of an SCR system, and then feedback type dynamic ammonia injection control is performed (for example, patent CN202010295306. X).
In view of the fact that most of the front parts of the ammonia spraying devices of the SCR system are vertical and non-reducing flues, the flowing uniformity and the corresponding relation of flue gas are obvious, and by combining the reaction mechanism of the SCR system, the research finds that the accurate control of the ammonia spraying branch pipe of the SCR system can be realized by the automatic ammonia spraying branch pipe control method based on the on-line monitoring data of the flue gas flow speed and the NOx concentration in the cross section of the inlet flue of the SCR system. The method can realize good ammonia nitrogen mixing equivalence ratio in the system, and the dynamic ammonia spraying control logic has strong self-adaptive capacity, and is suitable for safe, stable and long-period operation of the ammonia spraying control of the unit SCR system after ultralow emission reconstruction.
Disclosure of Invention
The technical problem is as follows: under the background of ultralow emission modification of coal-fired equipment, in order to further optimize the matching degree of the ammonia-nitrogen mixing equivalence ratio in the SCR system so as to improve the denitration efficiency of the SCR system and reduce ammonia escape, the method for automatically controlling the ammonia spraying branch pipe of the SCR system based on the on-line monitoring of the flow rate and NOx concentration of flue gas is provided, and the fine control of the ammonia spraying branch pipe of the SCR system is realized.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:
an SCR system ammonia injection branch pipe control method based on flow rate and NOx concentration monitoring is characterized by comprising the following steps:
step 1: measuring the flow velocity and NOx concentration of each sub-area smoke in the flue grid area on line;
step 2: determining flow velocity inertia factors of the sub-regions according to the measured flow velocity characteristics of the flue gas of each sub-region in the flue grid region, the unit load and the total air volume;
determining NOx concentration inert factors of the sub-regions according to the measured concentration characteristics of the NOx in the flue gas of each sub-region in the grid region of the flue, the unit load and the wind-coal ratio;
and step 3: determining an inert region and a non-inert region of NOx flux change by jointly analyzing NOx flux sensitivity in the sub-region based on the flow velocity inertia factor and the NOx concentration inertia factor;
and 4, step 4: the opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed value; the opening degree of the ammonia injection branch pipe valve corresponding to the non-inert area is a change value, and the changed opening degree of the ammonia injection branch pipe valve is determined by the set fuzzy rule base.
An online flue gas flow velocity sensor exists in each flue grid region, and the online flow velocity measurement result is a flue gas flow velocity discrete measurement point with a time tag.
The method for determining the flow velocity inertia factor of each subarea comprises the following steps:
obtaining a continuous fitting function u-f (L) by adopting a polynomial fitting method according to flow speed and unit load operation data with the same time tag in a sampling time period; k (l) ═ k (l)1L+b1，k1And b1Is the corresponding fitting coefficient;
obtaining a continuous fitting function u-f (A) by adopting a polynomial fitting method according to the flow speed and total air volume operation data with the same time label in a sampling time period; k (a) ═ k2A+b2，k2And b2Is the corresponding fitting coefficient;
determining a zonal flow rate inertia factor IFu：
Figure BDA0002951885760000031
In the formula:
Figure BDA0002951885760000032
to fit the partial derivative of the function u ═ f (l) to the unit load,
Figure BDA0002951885760000033
and fitting a function of u ═ f (A) on the partial derivative of the total air volume, wherein u is the flow rate, L is the unit load and A is the total air volume.
An online flue gas NOx concentration sensor is arranged in each flue grid region, and the online NOx concentration measurement result is a discrete flue gas NOx concentration measurement point with a time label.
The method for determining the concentration inertia factor of the subareas comprises the following steps:
obtaining a continuous fitting function c (g) (L) by adopting a polynomial fitting method according to the NOx concentration and unit load operation data with the same time label in a sampling time period; specifically, c ═ g (l) ═ c1L2+c2L+c3，c1、c2And c3Is the corresponding fitting coefficient;
obtaining a continuous fitting function c (g) (R) by adopting a polynomial fitting method according to the NOx concentration and wind-coal ratio operation data with the same time label in the sampling time period; specifically, c ═ g (r) ═ d1R2+d2R+d3，d1、d2And d3Is the corresponding fitting coefficient;
determining a concentration inert factor IF of a sub-zonec：
Figure BDA0002951885760000034
In the formula:
Figure BDA0002951885760000035
to be planned toThe resultant function C ═ g (l) the partial derivatives of the unit loads,
Figure BDA0002951885760000036
the fitting function C is the partial derivative of g (R) to the wind-coal ratio, C is the NOx concentration, L is the unit load, and R is the wind-coal ratio.
The method for determining the inert and non-inert regions of the NOx flux variation is as follows:
determining the joint inert factor IF:
IF＝αIFu+βIFc
in the formula: alpha + beta is 1, and the value of alpha is between 0.7 and 0.9;
for a given area inertia judgment standard xi, IF IF is less than or equal to xi, the corresponding sub area is an inertia area, otherwise, the corresponding sub area is a non-inertia area; the value of the area inertia judgment standard xi is determined by the unit furnace type, the ammonia spraying grid type and the flow field distribution characteristic, and the value rule is as follows:
Figure BDA0002951885760000037
in the formula: xii,jTaking 8-15; psi is the correlation coefficient of regional inertia judgement standard xi and the ammonia-spraying grid pattern, and the partition control ammonia-spraying grid pattern takes on value 1, and the linear control ammonia-spraying grid pattern takes on value 0.6 ~ 0.8. According to the online measurement results of the flow velocity and the NOx concentration in the flue grid area, the unit load and the theoretical ammonia spraying amount operation parameters, setting and establishing an ideal opening fuzzy rule base of the ammonia spraying branch pipe valve, and having the following general form:
Figure BDA0002951885760000041
in the formula: ki,jThe first corner mark of (A) represents the number of the ammonia injection branch pipes, from 1 to the total number of the branch pipes; ki,jThe second corner mark of (1) represents the number of working conditions equally divided according to the unit load, and j is more than or equal to 3;
Figure BDA0002951885760000042
the average opening degree of the ith ammonia injection branch pipe valve in each row (i.e. each working condition).
The opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed constant value, and the opening degree of the ammonia spraying branch pipe valve corresponding to the non-inert area is automatically regulated and controlled
Figure BDA0002951885760000043
And the opening degree of the valve of the ammonia injection branch pipe corresponding to the non-inert region is automatically regulated and controlled according to the fuzzy rule base, and the valve opening degree of the specific ammonia injection branch pipe in the adjacent working condition interval is calculated based on a linear difference method.
The valve opening matrix M in the general form of the fuzzy rule base is periodically self-updated according to the online measurement results of the flow velocity and the NOx concentration in the flue grid area, and the online self-updating is started under the conditions that:
Figure BDA0002951885760000044
in the formula: continuous use time of the T fuzzy rule base; t issetIs a preset online self-updating interval time; ki,j τ+1The opening degree of the ammonia spraying branch pipe valve at the time of tau + 1; ki,j τThe opening degree of the ammonia spraying branch pipe valve at the time tau; and theta is a preset ammonia spraying branch pipe valve opening drift tolerance error.
Therefore, the patent provides an SCR system ammonia injection control method based on flue gas 'flow velocity-NOx concentration' inertia factor analysis, which takes analysis of flue gas flow velocity and NOx concentration in the SCR system as a starting point.
Specifically, firstly, according to the online measurement result of the flow velocity in the flue grid area, carrying out sensitivity analysis on the flow velocity characteristics of the partitioned flue gas, unit load and total air volume, and determining the flow velocity inertia factor of the partitioned area; then according to the online measurement result of the NOx concentration in the flue grid region, carrying out sensitivity analysis on the NOx concentration characteristic of the partitioned flue gas, unit load and the wind-coal ratio, and determining the concentration inertia factor of the partitioned region; then, analyzing the NOx flux sensitivity in the subarea based on the flow velocity and concentration inertia factor combination, and determining an inert area and a non-inert area of the NOx flux change; finally, a reasonable and reliable ammonia injection control method of the SCR system is designed, namely: the opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed and unchangeable value, the opening degree of the ammonia spraying branch pipe valve corresponding to the non-inert area is automatically regulated, and the specific opening degree of the ammonia spraying branch pipe valve is determined by the set fuzzy rule base. The method can realize real-time matching optimization of the ammonia nitrogen equivalence ratio in the SCR system, and is beneficial to improving the ammonia utilization rate and reducing ammonia escape.
Has the advantages that: compared with the prior art, the invention has the advantages that: the method comprises the steps of respectively determining flow velocity inertia factors and concentration inertia factors of subareas by measuring and analyzing the flow velocity and NOx concentration in a flue grid area of the SCR system on line, jointly analyzing NOx flux sensitivity in the subareas based on the flow velocity and the NOx concentration inertia factors, determining an NOx flux change inertia area and a non-inertia area, and obtaining the automatic control method of the ammonia injection branch pipe based on the reaction mechanism of the SCR system. The method can realize the real-time matching optimization of the ammonia-smoke equivalence ratio in the SCR system, effectively improve the utilization rate of ammonia and reduce the ammonia escape.
Drawings
Fig. 1 is a flow chart of a control method of the present invention.
FIG. 2 is a schematic diagram of the mesh area division of the front flue section of the ammonia injection grid in the embodiment of the invention.
Detailed Description
The present invention is described in detail below with reference to the accompanying drawings, which are used for implementing the present invention on the premise of the technical solution, and it should be understood that the implementation case is for illustrating the present invention, but the protection scope of the present invention is not limited to the implementation case.
The implementation case is implemented by relying on an SCR system of a certain 600 MW-level coal-fired unit, is matched with a front-wall and rear-wall opposed-flow boiler, and adopts a urea hydrolysis ammonia preparation process. The size of the cross section of the front flue of the ammonia injection grid of the SCR system of the unit is 13500mm multiplied by 3200mm, on-line measurement equipment for the flow rate and the concentration of NOx is designed and installed on the basis of a static induction correlation velocity measurement principle and an ultraviolet differential absorption spectroscopy (DOAS) technology, the flow rate distribution characteristic, the concentration distribution characteristic of NOx and the flux distribution characteristic of the flue gas in the cross section of the front flue of the ammonia injection grid can be obtained in real time, and then the grid area of the cross section of the front flue of the ammonia injection grid is divided in combination with the type of the ammonia injection grid (as shown in figure 2), so that the on-line measurement result of the operation parameters. The specific implementation process is as follows:
step 1: according to the online measurement result of the flow velocity in the flue grid area, sensitivity analysis of the flow velocity characteristics of the partitioned flue gas, unit load and total air volume is carried out, and the flow velocity inertia factor of the partitioned area is determined.
Firstly, obtaining a continuous fitting function u-f (L) by adopting a polynomial fitting method according to flow velocity and unit load operation data with the same time tag in a sampling time period, then obtaining a continuous fitting function u-f (A) by adopting a polynomial fitting method according to the flow velocity and total air volume operation data with the same time tag in the sampling time period, and finally determining flow velocity inertia factors IF (intermediate frequency) of sub-regions according to the following methodu：
Figure BDA0002951885760000061
In the formula:
Figure BDA0002951885760000062
to fit the partial derivative of the function u ═ f (l) to the unit load,
Figure BDA0002951885760000063
is the partial derivative of the fitting function u ═ f (a) to the total air volume.
Step 2: according to the online measurement result of the NOx concentration in the flue grid region, sensitivity analysis of the NOx concentration characteristic of the partitioned flue gas, unit load and wind-coal ratio is carried out, and the concentration inertia factor of the partitioned region is determined.
Likewise, NOx rich for the same time tag over the sample periodObtaining continuous fitting function c (g) (L) by adopting a polynomial fitting method according to load operation data of the unit, obtaining continuous fitting function c (g) (R) by adopting a polynomial fitting method according to NOx concentration and wind-coal ratio operation data with the same time label in a sampling time period, and finally determining concentration inertia factor IF (intermediate frequency) of a sub-region according to the following methodc：
Figure BDA0002951885760000064
In the formula:
Figure BDA0002951885760000065
to fit the partial derivative of the function c to g (l) to the unit load,
Figure BDA0002951885760000066
is the partial derivative of the fitting function c ═ g (r) to the wind-coal ratio.
And step 3: determining an inert region and a non-inert region of NOx flux change based on the flow velocity and the NOx flux sensitivity in the NOx concentration inert factor joint analysis subarea;
the NOx flux sensitivity in the subarea is analyzed based on the flow velocity and the concentration inertia factor in a combined mode, and the NOx flux change inertia area and the non-inertia area are determined, wherein the NOx flux sensitivity in the subarea is determined through the combined inertia factor IF, and the calculation method is as follows:
IF＝αIFu+βIFc
in the formula: α + β is 1, and α is 0.8 in this embodiment.
And for a given area inertia judgment standard xi, IF the IF is less than or equal to xi, the corresponding sub-area is an inertia area, otherwise, the corresponding sub-area is a non-inertia area.
The value of the area inertia judgment standard xi is determined by the unit furnace type, the ammonia spraying grid type and the flow field distribution characteristic, and the value rule is as follows:
Figure BDA0002951885760000071
in the formula: xii,jTaking 8-15; xi1,jLine and xi2,jLine and xi3,jLine and xi4,jThe behavior unit has the boiler type characteristic that corresponding values respectively correspond to a four-corner tangential boiler, a front-wall and rear-wall opposed boiler, a circulating fluidized bed boiler and other boilers; xii,1Column and xii,2Column and xii,3Column and xii,4The corresponding values respectively correspond to the distribution uniformity C of the flow velocity of the flue gas before the ammonia injection gridv≤5％、5％＜Cv≤10％、10％＜Cv≤15％、15％＜Cv≤20％、CvIs more than 20 percent; psi is the correlation coefficient of regional inertia judgement standard xi and the ammonia-spraying grid pattern, and the partition control ammonia-spraying grid pattern takes on value 1, and the linear control ammonia-spraying grid pattern takes on value 0.6 ~ 0.8.
In one embodiment, the following values are established:
Figure BDA0002951885760000072
in one embodiment, the unit is a front-rear wall opposed boiler, and the flue gas flow velocity distribution uniformity C is arranged before an ammonia injection gridvThe diagnosis result is 14.21%, so the regional inertia judgment standard xi takes xi2,3(ii) a Because the ammonia injection grid type is a zone control ammonia injection grid type, psi is 1; thus, xi is taken to be xi in this embodiment2,310. Therefore, the inert area and the non-inert area corresponding to the ammonia injection branch pipe of the unit SCR system are determined as shown in the table 1.
Table 1: inert and non-inert characteristics of grid area corresponding to ammonia spraying branch pipe
Figure BDA0002951885760000073
And 4, step 4: the opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed and unchangeable value, the opening degree of the ammonia spraying branch pipe valve corresponding to the non-inert area is automatically regulated, and the specific opening degree of the ammonia spraying branch pipe valve is determined by the set fuzzy rule base.
According to the online measurement results of the flow velocity and the NOx concentration in the flue grid region, unit loads (300MW, 350MW, 400MW, 450MW, 500MW, 550MW, 600MW, 650MW) and theoretical ammonia injection quantity operation parameters, setting and establishing an ideal opening fuzzy rule base of the ammonia injection branch pipe valve, wherein the method has the following form in the embodiment:
Figure BDA0002951885760000081
in the formula: ki,jThe first corner mark of (A) represents the number of the ammonia injection branch pipes, from 1 to the total number of the branch pipes; ki,jThe second corner mark of (1) represents the number of working conditions equally divided according to the unit load, and j is more than or equal to 3;
Figure BDA0002951885760000082
the average opening degree of the ith ammonia injection branch pipe valve in each row (i.e. each working condition).
The opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed constant value, and the opening degree of the ammonia spraying branch pipe valve corresponding to the non-inert area is automatically regulated, and the method is characterized in that the fixed constant opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is
Figure BDA0002951885760000083
And the opening degree of the valve of the ammonia injection branch pipe corresponding to the non-inert region is automatically regulated and controlled according to the fuzzy rule base, and the valve opening degree of the specific ammonia injection branch pipe in the adjacent working condition interval is calculated based on a linear difference method.
Carrying out regular self-updating according to the online measurement results of the flow velocity and the NOx concentration in the flue grid region, wherein the conditions for starting the online self-updating are as follows:
Figure BDA0002951885760000084
in the formula: continuous use time of the T fuzzy rule base; t issetIs a preset online self-updating interval time; ki,j τ+1The opening degree of the ammonia spraying branch pipe valve at the time of tau + 1; ki,j τThe opening degree of the ammonia spraying branch pipe valve at the time tau; and theta is a preset ammonia spraying branch pipe valve opening drift tolerance error.
The embodiment can show that the method for controlling ammonia injection of the SCR system based on flue gas flow velocity-NOx concentration inertia factor analysis can realize accurate control of the ammonia injection branch pipe of the SCR system of coal-fired equipment and is beneficial to matching the ammonia nitrogen mixing equivalence ratio in the system.
As described above, although the embodiments of the present invention have been described in connection with the embodiments and the accompanying drawings, they should not be construed as limiting the present invention itself. On the basis of the technical scheme of the invention, various modifications or changes which can be made by any unit or person without creative labor are still within the protection scope of the invention.

Claims (10)

1. An SCR system ammonia injection branch pipe control method based on flow rate and NOx concentration monitoring is characterized by comprising the following steps:
step 1: measuring the flow velocity and NOx concentration of each sub-area smoke in the flue grid area on line;
step 2: determining flow velocity inertia factors of the sub-regions according to the measured flow velocity characteristics of the flue gas of each sub-region in the flue grid region, the unit load and the total air volume;
determining NOx concentration inert factors of the sub-regions according to the measured concentration characteristics of the NOx in the flue gas of each sub-region in the grid region of the flue, the unit load and the wind-coal ratio;
and step 3: determining an inert region and a non-inert region of NOx flux change by jointly analyzing NOx flux sensitivity in the sub-region based on the flow velocity inertia factor and the NOx concentration inertia factor;
and 4, step 4: the opening degree of the ammonia spraying branch pipe valve corresponding to the inert area is a fixed value; the opening degree of the ammonia injection branch pipe valve corresponding to the non-inert area is a change value, and the changed opening degree of the ammonia injection branch pipe valve is determined by the set fuzzy rule base.
2. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 1, wherein an online flue gas flow velocity sensor is arranged in each flue grid region, and the online flow velocity measurement result is a discrete flue gas flow velocity measurement point with a time tag.
3. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 2, wherein the method for determining the flow rate inertia factor of each subarea comprises the following steps:
obtaining a continuous fitting function u-f (L) by adopting a polynomial fitting method according to flow speed and unit load operation data with the same time tag in a sampling time period; k (l) ═ k (l)1L+b1，k1And b1Is the corresponding fitting coefficient;
obtaining a continuous fitting function u-f (A) by adopting a polynomial fitting method according to the flow speed and total air volume operation data with the same time label in a sampling time period; k (a) ═ k2A+b2，k2And b2Is the corresponding fitting coefficient;
determining a zonal flow rate inertia factor IFu：
Figure FDA0002951885750000011
In the formula:
Figure FDA0002951885750000012
to fit the partial derivative of the function u ═ f (l) to the unit load,
Figure FDA0002951885750000013
and fitting a function of u ═ f (A) on the partial derivative of the total air volume, wherein u is the flow rate, L is the unit load and A is the total air volume.
4. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 1, wherein an online flue gas NOx concentration sensor is arranged in each flue grid region, and the online NOx concentration measurement result is a discrete measuring point of the flue gas NOx concentration with a time label.
5. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 1, wherein the method for determining the concentration inertia factor of the subareas is as follows:
obtaining a continuous fitting function c (g) (L) by adopting a polynomial fitting method according to the NOx concentration and unit load operation data with the same time label in a sampling time period; specifically, c ═ g (l) ═ c1L2+c2L+c3，c1、c2And c3Is the corresponding fitting coefficient;
obtaining a continuous fitting function c (g) (R) by adopting a polynomial fitting method according to the NOx concentration and wind-coal ratio operation data with the same time label in the sampling time period; specifically, c ═ g (r) ═ d1R2+d2R+d3，d1、d2And d3Is the corresponding fitting coefficient;
determining a concentration inert factor IF of a sub-zonec：
Figure FDA0002951885750000021
In the formula:
Figure FDA0002951885750000022
to fit the partial derivative of the function C-g (l) to the unit load,
Figure FDA0002951885750000023
the fitting function C ═ g (R) partial derivatives of the wind-coal ratio, C is the NOx concentration, L is the unit load, R is the wind-coal ratio,
Figure FDA0002951885750000024
in order to be the average load,
Figure FDA0002951885750000025
is the average air-coal ratio.
6. The SCR system ammonia injection manifold control method of claim 1, wherein the method of determining the NOx flux change inert zone and the non-inert zone is:
determining the joint inert factor IF:
IF＝αIFu+βIFc
in the formula: alpha + beta is 1, and the value of alpha is between 0.7 and 0.9;
for a given area inertia judgment standard xi, IF IF is less than or equal to xi, the corresponding sub area is an inertia area, otherwise, the corresponding sub area is a non-inertia area;
the value of the area inertia judgment standard xi is determined by the unit furnace type, the ammonia spraying grid type and the flow field distribution characteristic, and the value rule is as follows:
Figure FDA0002951885750000026
in the formula: xii，jTaking 8-15; psi is the correlation coefficient of regional inertia judgement standard xi and the ammonia-spraying grid pattern, and the partition control ammonia-spraying grid pattern takes on value 1, and the linear control ammonia-spraying grid pattern takes on value 0.6 ~ 0.8.
7. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 1, wherein an ideal opening fuzzy rule base of the ammonia injection branch pipe valve is set and established according to the online measurement results of the flow velocity and the NOx concentration in the flue grid area, the unit load and the theoretical ammonia injection amount operation parameters:
Figure FDA0002951885750000031
in the formula: m is a valve opening matrix, Ki，jThe first corner mark of (A) represents the number of the ammonia injection branch pipes, from 1 to the total number of the branch pipes; ki，jSecond corner markRepresenting the number of working conditions equally divided according to the unit load, wherein j is more than or equal to 3;
Figure FDA0002951885750000037
the average opening degree of the ith ammonia spraying branch pipe valve in each row; ki，jThe opening degree of the ith branch pipe under the jth working condition;
Ki，j＝F(q)
in the formula: f (q) is the inherent flow-opening characteristic curve function of the ammonia injection branch pipe valve, and q is the flow of ammonia;
Figure FDA0002951885750000032
in the formula (I), the compound is shown in the specification,
Figure FDA0002951885750000033
the average flow speed in the load interval of the divided unit,
Figure FDA0002951885750000034
average NOx concentration in divided unit load interval, ArIs the area of the flue grid region, MNH3Molar mass of NH3, MNOxIs the molar mass of NOx.
8. The method as claimed in claim 7, wherein the inert region corresponds to a fixed opening of the ammonia injection branch valve
Figure FDA0002951885750000035
And the opening degree of the valve of the ammonia spraying branch pipe corresponding to the non-inert area is automatically regulated and controlled according to the fuzzy rule base, and the opening degree of the valve in the adjacent working condition interval of the ammonia spraying branch pipe corresponding to any one non-inert area is calculated based on a linear difference method.
9. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 7, wherein the valve opening matrix M is periodically self-updated according to the flow rate and the online measurement result of NOx concentration in the flue grid region, and the conditions for starting the online self-update are as follows:
Figure FDA0002951885750000036
in the formula: continuous use time of the T fuzzy rule base; t issetIs a preset online self-updating interval time; ki，j τ+1The opening degree of the ammonia spraying branch pipe valve at the time of tau + 1; ki，j τThe opening degree of the ammonia spraying branch pipe valve at the time tau; and theta is a preset ammonia spraying branch pipe valve opening drift tolerance error.
10. The method for controlling the ammonia injection branch pipe of the SCR system according to claim 9, wherein the tolerance error theta of the valve opening drift of the ammonia injection branch pipe is 5-20%.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114542247A (en) * 2022-01-18 2022-05-27 潍柴动力股份有限公司 SCR system and engine
CN115099171A (en) * 2022-06-30 2022-09-23 齐鲁工业大学 Method for obtaining flue gas flow field distribution characteristics of catalyst layer flue section of SCR system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105126616A (en) * 2015-08-20 2015-12-09 东南大学 SCR denitration system ammonia spraying optimization method based on weight valve regulation and control
CN108404661A (en) * 2018-04-28 2018-08-17 南京新瓦特智控科技有限公司 The full load of a kind of leveling of on-line velocity field and concentration field measurement precisely sprays ammonia system
CN108664006A (en) * 2018-07-02 2018-10-16 大唐环境产业集团股份有限公司 It is a kind of that ammonia optimization method and system are intelligently sprayed based on the SCR denitration of zonal control and Dynamic matrix control

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105126616A (en) * 2015-08-20 2015-12-09 东南大学 SCR denitration system ammonia spraying optimization method based on weight valve regulation and control
CN108404661A (en) * 2018-04-28 2018-08-17 南京新瓦特智控科技有限公司 The full load of a kind of leveling of on-line velocity field and concentration field measurement precisely sprays ammonia system
CN108664006A (en) * 2018-07-02 2018-10-16 大唐环境产业集团股份有限公司 It is a kind of that ammonia optimization method and system are intelligently sprayed based on the SCR denitration of zonal control and Dynamic matrix control

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
张佳佳等: "涡流混合式SCR脱硝系统喷氨优化调整试验研究", 《洁净煤技术》 *
翁骥等: "SCR脱硝系统分区控制式喷氨格栅的优化", 《环境工程学报》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114542247A (en) * 2022-01-18 2022-05-27 潍柴动力股份有限公司 SCR system and engine
CN115099171A (en) * 2022-06-30 2022-09-23 齐鲁工业大学 Method for obtaining flue gas flow field distribution characteristics of catalyst layer flue section of SCR system
CN115099171B (en) * 2022-06-30 2024-02-27 齐鲁工业大学 Method for acquiring distribution characteristics of flue gas flow field of cross section of catalyst layer flue of SCR (selective catalytic reduction) system

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