Boiler denitration flue gas ammonia escape detection system and detection method

Abstract

The invention discloses a boiler denitration flue gas ammonia escape detection system and detection method, and belongs to the technical field of ammonia escape detection, the boiler denitration flue gas ammonia escape detection system comprises a flue gas sampling and pretreatment unit, a reaction and color development unit, an image acquisition unit, and a processing and control unit; the reaction and color development unit comprises a reaction tank A, a reaction tank B, a color developing agent storage unit, a double-channel injection pump and a color development reaction adjusting unit; a color developing agent is stored in the color developing agent storage unit; the image acquisition unit comprises two high-speed industrial cameras which are used for respectively and synchronously acquiring reaction images of the reaction tank A and the reaction tank B under equal shooting conditions; the processing and control unit is used for analyzing and processing reaction images of the reaction tank A and the reaction tank B, eliminating apparent interference of particulate matters reacted in the reaction tank B and chemical inhibition interference of chromogenic reaction, and obtaining a final ammonia escape index If which is evaluated to approach to the real ammonia escape concentration in the flue gas. The method is faster and more accurate in judging whether ammonia escape exists or not and whether the ammonia escape exceeds the national specified standard or not.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ammonia escape detection, and relates to a boiler denitration flue gas ammonia escape detection system and a detection method. BACKGROUND

[0002] Ammonia escape refers to a phenomenon that ammonia gas or ammonia water solution is not completely controlled and released into the surrounding environment due to various reasons in an industrial process, especially in a process in which ammonia is used as a chemical substance or a catalyst; ammonia escape not only damages the environment but also may pose a threat to human health.

[0003] At present, ammonia escape detection equipment is mainly used for detecting the concentration value of ammonia gas, but the actual flue gas also contains components such as particulate matter, sulfur dioxide and carbon dioxide, which can seriously interfere with the real concentration value of ammonia gas, the detection data is inaccurate and the data detection time is long, it is difficult to judge whether ammonia escape exceeds the standard in a short time, and the timeliness of ammonia escape treatment is affected. SUMMARY

[0004] The purpose of the present application is to provide a boiler denitration flue gas ammonia escape detection system and a detection method, which solves the problem that the current ammonia escape detection equipment mainly detects the specific concentration value, on the one hand the data is inaccurate, on the other hand the data detection time is long, it is difficult to judge whether ammonia escape exceeds the standard in a short time, and the timeliness of ammonia escape treatment is affected.

[0005] The technical scheme adopted by the present application is as follows: A boiler denitration flue gas ammonia escape detection system, comprising a flue gas sampling and pretreatment unit, a reaction and color development unit, an image acquisition unit and a processing and control unit. The flue gas sampling and pretreatment unit comprises a heated sampling probe, a gas distributor, a selective ammonia remover and a second bypass pipeline. The heated sampling probe is used to extract raw flue gas from the denitration system outlet flue and heat it to prevent water vapor condensation. The gas distributor is in communication with the heated sampling probe and is used to divide the inhaled raw flue gas into a first path and a second path. The selective ammonia remover is in communication with the first path outlet of the gas distributor and is used to specifically adsorb and remove all ammonia gas in the flue gas while allowing particulate matter to pass through without damage, and outputs a first standard sample S1. The second bypass pipeline is in communication with the second path outlet of the gas distributor and outputs a second standard sample S2. The reaction and color development unit comprises a reaction tank A, a reaction tank B, a color developing agent storage unit, a double-channel injection pump and a color development reaction adjusting unit. The reaction pool A and the reaction pool B are transparent optical reaction pools made of the same material and the same size, the reaction pool A is connected with the first standard sample S1, and the reaction pool B is connected with the second standard sample S2. The chromogenic agent storage unit stores the chromogenic agent, and injects the chromogenic agent into the reaction pool A and the reaction pool B in equal amounts through a double-channel injection pump, adjusts the chromogenic reaction parameters through the chromogenic reaction adjustment unit, and performs the chromogenic reaction; The image acquisition unit includes two high-speed industrial cameras, which are used to synchronously and equally acquire the reaction images of the reaction pool A and the reaction pool B under the same shooting conditions; The processing and control unit is used for analyzing and processing the reaction images of the reaction pool A and the reaction pool B, eliminating the apparent interference of particulate matters in the reaction of the reaction pool B and the chemical inhibition interference of the chromogenic reaction, obtaining the final ammonia escape index If which is close to the real ammonia escape concentration in the flue gas, and comparing If with a threshold value T, if If>T, it is determined that the ammonia escape is over-standard, and an alarm is triggered, if If≤T, it is determined to be normal; The threshold value T is the standard ammonia gas with a concentration equal to the national legal emission limit value, and the final ammonia escape index obtained through the above system unit is set as the threshold value T.

[0006] Further, the selective ammonia removal device is a device internally provided with porous materials impregnated with phosphoric acid or sulfuric acid.

[0007] Further, the chromogenic agent is a copper ammonia complex chromogenic agent, which includes a copper sulfate-potassium sodium tartrate mixed solution.

[0008] Further, the mass ratio of the copper sulfate and the potassium sodium tartrate is 1:3 A detection method of a boiler denitration flue gas ammonia detection system, the method comprises: From the outlet flue of the denitration system, the original flue gas is extracted through a heating sampling probe, and the original flue gas is equally divided into two paths: The first path: the flue gas is connected with the selective ammonia removal device, and all ammonia gas in the flue gas is specifically adsorbed and removed, but the particulate matters are allowed to pass through without damage, and the output is the first standard sample S1; The second path: directly bypasses without any treatment, and the output is the second standard sample S2; The first standard sample S1 and the second standard sample S2 are respectively connected with the same two transparent reaction pools, which are the reaction pool A and the reaction pool B, and the copper ammonia complex chromogenic agent is synchronously and equally injected into the two reaction pools to perform the chromogenic reaction under the oxygen condition; From the beginning of the injection of the copper ammonia complex chromogenic agent, the high-speed camera synchronously photographs the images of the two reaction pools at a fixed time interval, and continues until the reaction reaches the platform period, and two groups of image sequences Image-S1(t) and Image-S2(t) are obtained; the photographing positions and photographing parameters of the two reaction pools are completely consistent. Select the image where the reaction reaches the plateau from the image sequence, obtain two end-point images, including Image-S1 final and Image-S2 final ; After pixel-level registration of the two end-point images, the first image gray correction is performed to generate an image Image-S3 that eliminates the apparent interference of particulate matter; From Image-S3, the ammonia concentration feature parameters are extracted, including the average intensity of the blue channel Pc, the average saturation of the image Ps, and the standard deviation of the image gray value Pu. Based on the average intensity of the blue channel Pc, the average saturation of the image Ps, and the standard deviation of the image gray value Pu, the apparent ammonia escape index Ia is obtained through a weighted algorithm, which is used to evaluate the color development reaction intensity detected by the optical system under the current measurement conditions and eliminate the influence of particulate matter optical obstruction; The image sequence Image-S2(t) of the second standard sample S2 is analyzed, and a color depth-time reaction curve is constructed. The maximum slope Vmr of the reaction curve and the time T90r required for the color depth to reach 90% of the final stable value from the baseline are extracted. The ideal values Vmi and T90i measured under the calibration particulate-free environment using pure standard ammonia gas are compared, and the λ factor is calculated by the formula: λ = α * (Vmr / Vmi) + β * (T90 / T90r), where α and β are preset weights, α + β = 1, and λ is the reaction effectiveness verification factor. When λ equals 1, the reaction is normal, and when λ < 1, the reaction is inhibited; The apparent ammonia escape index Ia is modified by the λ factor to compensate for the deviation caused by chemical inhibition, and the final ammonia escape index If is obtained. The final ammonia escape index If is used to evaluate whether the true ammonia escape concentration in the current flue gas exceeds the limit value; If = Ia / λ, If is the final ammonia escape index, and Ia is the apparent ammonia escape index; If is compared with the threshold value T. If If > T, it is determined that the ammonia escape exceeds the standard, and an alarm is triggered. If If ≤ T, it is determined to be normal; The threshold value T is the standard ammonia gas with a concentration equal to the national legal emission limit value. The above steps are repeated to obtain the final ammonia escape index, which is set as the threshold value T.

[0009] Further, after pixel-level registration of the two end-point images, the first image gray correction is performed. The first image gray correction is performed by executing Image-S3 = Image-S2 final - k*Image-S1 final , Image-S3 = Image-S2 final - k*Image-S1final The operation method comprises the following steps: Image-S1 final and Image-S2 final Convert the color image into a gray-scale image to obtain two gray-scale value matrices G-S1(x, y) and G-S2(x, y), wherein (x, y) is a pixel coordinate, and the gray-scale value is normalized to the range of [0, 1], wherein 0 is black and 1 is white; a background reference region is defined in the image, and the background reference region is a region without color development reaction and includes the edge of the reaction cell; k is a dynamic coefficient, and the method for obtaining k is as follows: Extract the gray-scale values in the background reference region in the gray-scale images G-S1(x, y) and G-S2(x, y), and assume that there are N pixels in the background reference region, and the average value is taken: N gray-scale values [g1-s1, g2-s1,..., gN-s1] are extracted from G-S1, and mean-S1 = (g1-s1+ g2-s1 +... + gN-s1) / N; wherein mean-S1 is the average gray-scale value in the background reference region in G-S1; N gray-scale values [g1-s2, g2-s2,..., gN-s2] are extracted from G-S2, and mean-S2 = (g1-s2+ g2-s2 +... + gN-s2) / N; wherein mean-S2 is the average gray-scale value in the background reference region in G-S2; k = mean-S2 / mean-S1; Perform pixel-by-pixel difference calculation on each pixel point (x, y) in the gray-scale images G-S1(x, y) and G-S2(x, y): G-S3(x, y) = G-S2(x, y) - k*G-S1(x, y), and G-S3(x, y) is the gray-scale matrix after difference, which is displayed as an image Image-S3; if G-S2(x, y) - k*G-S1(x, y) is negative or exceeds the range, perform truncation processing, and G-S3(x, y) = max(0, min(G-S2(x, y) - k*G-S1(x, y), 1).

[0010] In summary, due to the adoption of the above technical solutions, the present application has the following beneficial effects: The application discloses a boiler denitration flue gas ammonia escape detection system and a detection method. The first standard sample S1 does not contain ammonia gas and only contains particulate matter, and no color developing reaction occurs after the first standard sample S1 is mixed with a color developing agent, so that the apparent (physical level) interference caused by the particulate matter is eliminated by taking the first standard sample S1 as a sample; since the color developing agent in the application is a copper sulfate ammonia complex color developing agent, the color developing agent does not react with other components (sulfur dioxide, carbon dioxide) and other gases in the flue gas under normal conditions, so that the interference of the above-mentioned acid gases is excluded from the chemical color developing reaction, and the chemical inhibition interference effect caused by the particulate matter is further eliminated by analyzing the reaction process of the second standard sample; through the two corrections, the final ammonia escape index that is most close to the ammonia concentration evaluation index in the real flue gas can be obtained, and whether the ammonia escape in the flue gas exceeds the standard can be quickly and accurately judged through the comparison of the final ammonia escape index. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings, wherein: Figure 1 It is a boiler denitration flue gas ammonia escape detection method flow chart; Figure 2 It is a color developing reaction color change process; DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and advantages of the application more clear, the following will further describe the application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application, that is, the described embodiments are only some of the embodiments of the application, but not all the embodiments. The components of the embodiments of the application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0013] The following detailed description of embodiments of the application in the drawings provided is not intended to limit the scope of the application claimed, but merely represents selected embodiments of the application. Based upon the embodiments of the application, all other embodiments that would be obtained by one skilled in the art without having to resort to inventive labor are within the scope of the application claimed.

[0014] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one from another entity or action, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more limitations, foreclose the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0015] The features and characteristics of the application are described in further detail below in connection with embodiments.

[0016] Embodiment 1 The preferred embodiment of the application provides a boiler denitration flue gas ammonia escape detection system, comprising a flue gas sampling and pretreatment unit, a reaction and color development unit, an image acquisition unit, a processing and control unit; The flue gas sampling and pretreatment unit comprises a heated sampling probe, a gas distributor, a selective ammonia remover, and a second bypass pipeline; The heated sampling probe is used to extract raw flue gas from the denitration system outlet flue and heat it to prevent water vapor condensation; The gas distributor is in communication with the heated sampling probe and is used to divide the inhaled raw flue gas into a first path and a second path; The selective ammonia remover is in communication with the first path outlet of the gas distributor and is used to specifically adsorb and remove all ammonia gas in the flue gas while allowing particulate matter to pass through without damage, outputting a first standard sample S1; The second bypass pipeline is in communication with the second path outlet of the gas distributor and outputs a second standard sample S2; The reaction and color development unit comprises a reaction pool A, a reaction pool B, a color developing agent storage unit, a double-channel injection pump, and a color development reaction adjustment unit; The reaction pool A and the reaction pool B are transparent optical reaction pools made of the same material and the same size, the reaction pool A is connected to the first standard sample S1, and the reaction pool B is connected to the second standard sample S2; The chromogenic agent storage unit stores the chromogenic agent and injects the chromogenic agent into the reaction pool A and the reaction pool B by a double-channel injection pump, and adjusts the chromogenic reaction parameters by the chromogenic reaction adjustment unit to perform the chromogenic reaction. The image acquisition unit includes two high-speed industrial cameras, which acquire the reaction images of the reaction pool A and the reaction pool B under the same shooting conditions. The processing and control unit is used for analyzing and processing the reaction images of the reaction pool A and the reaction pool B, eliminating the apparent interference of particulate matters in the reaction of the reaction pool B and the chemical inhibition interference of the chromogenic reaction, obtaining the final ammonia escape index If which approaches the real ammonia escape concentration in the flue gas, and comparing If with a threshold value T, if If>T, determining that the ammonia escape is over-standard and triggering an alarm, and if If≤T, determining that it is normal. The threshold value T is a standard ammonia gas with a concentration equal to the national legal emission limit value, and the final ammonia escape index obtained by the above system unit is set as the threshold value T.

[0017] The selective ammonia remover is a device internally provided with porous materials impregnated with phosphoric acid or sulfuric acid.

[0018] Example 2:

[0019] This embodiment is based on example 1, and the detection method of the boiler denitration flue gas ammonia detection system includes the following steps: S100, from the outlet flue of the denitration system, the original flue gas is extracted by a heating sampling probe, and the original flue gas is equally divided into two paths: The first path: the flue gas is introduced into the selective ammonia remover, and all the ammonia gas in the flue gas is specifically adsorbed and removed, but the particulate matters are allowed to pass through without damage, and the output is the first standard sample S1; the first standard sample S1 is flue gas without ammonia gas but containing particulate matters and other substances; The second path: directly bypasses without any treatment, and outputs the second standard sample S2; S110, the first standard sample S1 and the second standard sample S2 are introduced into the same two transparent reaction pools, respectively, as reaction pool A and reaction pool B, and copper ammonia complex chromogenic agent is synchronously and equally injected into the two reaction pools to perform chromogenic reaction under oxygen condition based on ammonia excess reaction; S120, from the start of injecting the copper ammonia complex chromogenic agent, the high-speed camera synchronously shoots the images of the two reaction pools at a fixed time interval, and continues until the reaction reaches the platform period, obtaining two image sequences Image-S1(t) and Image-S2(t); the shooting positions and parameters of the two reaction pools are completely consistent; S130, the images at the platform period are selected from the image sequences to obtain two end-point images, including Image-S1 final and Image-S2final After pixel-level registration of the two end-point images, the first image gray correction is performed to generate an image Image-S3 that eliminates apparent interference of particulate matter; the specific steps are as follows: After pixel-level registration of the two end-point images, the first image gray correction is performed to generate an image Image-S3 that eliminates apparent interference of particulate matter; the specific steps are as follows: final -k*Image-S1 final Operation, Image-S3= Image-S2 final -k*Image-S1 final The calculation method of the operation includes: Image-S1 final and Image-S2 final are converted from color images to gray images to obtain two gray value matrices G-S1(x, y) and G-S2(x, y), wherein (x, y) is the pixel coordinate, and the gray value is normalized to the range of [0, 1], wherein 0 is black and 1 is white; a background reference area is defined in the image, and the background reference area is a region without color development reaction, including the edge of the reaction cell; k is a dynamic coefficient, and the acquisition method of k is as follows: The gray values in the background reference area in the gray images G-S1(x, y) and G-S2(x, y) are extracted, assuming that there are N pixels in the background reference area, and the average value is taken: N gray values [g1-s1, g2-s1,..., gN-s1] are extracted from G-S1, and mean-S1 = (g1-s1+ g2-s1 +... + gN-s1) / N; wherein mean-S1 is the average gray value in the background reference area in G-S1; N gray values [g1-s2, g2-s2,..., gN-s2] are extracted from G-S2, and mean-S2 = (g1-s2+ g2-s2 +... + gN-s2) / N; wherein mean-S2 is the average gray value in the background reference area in G-S2; k = mean-S2 / mean-S1; Performing pixel-by-pixel difference, calculating each pixel point (x, y) in the gray-scale images G-S1(x, y) and G-S2(x, y): G-S3(x, y) = G-S2(x, y) - k*G-S1(x, y), G-S3(x, y) is the gray-scale matrix after difference, which is displayed as an image Image-S3, if G-S2(x, y) - k*G-S1(x, y) is negative or exceeds the range, perform truncation processing, G-S3(x, y) = max(0, min(G-S2(x, y) - k*G-S1(x, y), 1)); S140, extracting ammonia concentration feature parameters from Image-S3, including the average intensity of the blue channel Pc, the average saturation of the image Ps, and the standard deviation of the image gray value Pu, based on the average intensity of the blue channel Pc, the average saturation of the image Ps, and the standard deviation of the image gray value Pu, the apparent ammonia escape index Ia is obtained by a weighted algorithm, and the apparent ammonia escape index Ia is used to evaluate the color development reaction intensity detected by the optical system under the current measurement conditions and eliminate the influence of particulate matter optical obstruction; S150, analyzing the image sequence Image-S2(t) of the second standard sample S2, constructing its color depth-time reaction curve, extracting the maximum slope Vmr of the reaction curve and the time T90r required for the color depth to reach 90% of the final stable value from the baseline, comparing with the ideal values Vmi and T90i measured by using pure standard ammonia gas in a calibration particulate-free environment, and calculating the λ factor through the formula: λ = α*(Vmr / Vmi) + β*(T90 / T90r), wherein α and β are preset weights, α + β = 1, and λ is the reaction effectiveness verification factor, λ = 1 indicates normal reaction, and λ < 1 indicates inhibited reaction; S160, modifying the apparent ammonia escape index Ia with the λ factor to compensate for the deviation caused by chemical inhibition, and obtaining the final ammonia escape index If, which is used to evaluate whether the real ammonia escape concentration in the current flue gas exceeds the limit value; If = Ia / λ, If is the final ammonia escape index, and Ia is the apparent ammonia escape index; Comparing If with the threshold value T, if If > T: determining that the ammonia escape exceeds the standard, and triggering an alarm; if If ≤ T, determining that it is normal; The threshold value T is the standard ammonia gas with a concentration equal to the national legal emission limit value, and the above steps are repeated to obtain a final ammonia escape index, which is set as the threshold value T. According to the standards HJ562-2010 and HJ563-2010, the ammonia escape limit values of the SCR and SNCR denitration systems are 2.5 mg / m³ (3 ppm) and 8 mg / m³ (10 ppm), respectively.

[0020] The color developing agent is a copper-ammonia complex color developing agent, and the copper sulfate-potassium sodium tartrate mixed solution is used, and the mass ratio of copper sulfate to potassium sodium tartrate is 1:3.

[0021] The application is mainly based on the fact that ammonia is different from sulfur dioxide and carbon dioxide, which are acidic gases dissolved in water, and specifically reacts with copper sulfate to form a complex, and the change in the blue depth of the complex reaction is used to modify the image of the reaction endpoint based on image analysis technology, thereby improving the accuracy of the entire detection, and the application has reference value. The change mechanism of the complex reaction of ammonia and copper sulfate is as follows: CuSO4 + 2NH3·H2O = Cu(OH)2↓ + (NH4)2SO4, CuSO4 + 4NH3·H2O = [Cu(NH3)4]SO4 + 4H2O (excess ammonia); The copper sulfate solution is originally blue, and after adding excess ammonia water, the solution color will gradually change to dark blue, because of the specific structure of the copper-ammonia complex ion, and the spatial configuration of this ion is square planar. Therefore, the application is completely suitable for gray scale analysis, and the color developing reaction of the application is carried out under stirring conditions, and the reaction endpoint is uniform dark blue, as shown in Figure 2 .

[0022] The application prepares a gas sample without ammonia but with particulate matter (S1, no color developing reaction, no chemical inhibition factor) and a gas sample with ammonia and particulate matter (S2) by using a selective ammonia removal device, obtains the color developing images of the two samples by synchronous color developing and image acquisition, and eliminates the optical interference of the particulate matter physical shielding from the gas sample (S2) mainly by image gray value operation. The particulate matter not only produces optical interference, but also adsorbs reactants to inhibit the color developing chemical reaction itself, resulting in a lower measurement value. The application analyzes the kinetic process of the color developing reaction of the S2 sample, the maximum reaction rate Vmr, the time T90r at which 90% of the stable value is reached, and compares them with the parameters (Vmi, T90i) in the ideal non-interference state to calculate a reaction effectiveness verification factor λ. The factor quantifies the degree of inhibition of the chemical reaction. Finally, the apparent measurement value Ia is corrected by the formula If = Ia / λ to compensate for the deviation caused by chemical inhibition, and the final index If close to the true ammonia concentration is obtained, which has reference significance.

[0023] Some particulate matter will adsorb the color developing agent component or ammonia molecules, resulting in a slower reaction rate, incomplete reaction, and a lighter blue color than ideal; Ia is calculated from the image color depth, and a lighter blue color directly leads to a lower calculated value of Ia, which is compared with the threshold T, even if the true ammonia concentration has exceeded the standard, the distorted Ia may be lower than the threshold, thereby causing the system to miss the alarm; the core role of the chemical inhibition factor λ is to find and quantify this Ia "distortion".

[0024] The above merely describes the preferred embodiments of the present application and is not intended to limit the protection scope of the present application, and any modifications, equivalent replacements, and improvements made by any person skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A boiler denitrification flue gas ammonia slip detection system, characterized in that: It includes a flue gas sampling and pretreatment unit, a reaction and color development unit, an image acquisition unit, and a processing and control unit; The flue gas sampling and pretreatment unit includes a heated sampling probe, a gas distributor, a selective ammonia remover, and a second bypass pipeline; Heated sampling probe: used to extract raw flue gas from the outlet flue of the denitrification system and heat it to prevent water vapor condensation; Gas distributor: connected to the heated sampling probe, used to divide the inhaled raw flue gas into a first path and a second path; Selective ammonia remover: connected to the first outlet of the gas distributor, used to specifically adsorb and remove all ammonia in the flue gas, while allowing particulate matter to pass through without damage, and outputting the first standard sample S1; Second bypass pipeline: connected to the second outlet of the gas distributor, outputting the second standard sample S2; The reaction and color development unit includes reaction tank A, reaction tank B, color developer storage unit, dual-channel injection pump, and color development reaction adjustment unit; The reaction cell A and reaction cell B are transparent optical reaction cells made of the same material and the same size. The first standard sample S1 is introduced into the reaction cell A, and the second standard sample S2 is introduced into the reaction cell B. The colorimetric reagent storage unit stores the colorimetric reagent and injects equal amounts of the colorimetric reagent into reaction tank A and reaction tank B through a dual-channel injection pump. The colorimetric reaction parameters are adjusted by the colorimetric reaction adjustment unit to carry out the colorimetric reaction. The image acquisition unit includes two high-speed industrial cameras, which simultaneously acquire reaction images of reaction tank A and reaction tank B under the same shooting conditions. The processing and control unit is used to analyze and process the reaction images of reaction tank A and reaction tank B, eliminate the apparent interference of particulate matter in the reaction of reaction tank B and the chemical inhibition interference of the color reaction, and obtain the final ammonia slip index If, which is close to the true ammonia slip concentration in the flue gas. If is compared with the threshold T. If > T: it is determined that the ammonia slip exceeds the standard and an alarm is triggered; if If ≤ T, it is determined to be normal. The threshold T is the final ammonia escape index obtained by introducing standard ammonia gas with a concentration equal to the national statutory emission limit through the above system unit, and the final ammonia escape index is set as the threshold T.

2. The boiler denitrification flue gas ammonia slip detection system according to claim 1, characterized in that: The selective ammonia remover is a device internally filled with a porous material impregnated with phosphoric acid or sulfuric acid.

3. The boiler denitrification flue gas ammonia escape detection system according to claim 1, characterized in that: The colorimetric agent is a copper ammonia complex colorimetric agent, including a mixed solution of copper sulfate and potassium sodium tartrate.

4. The boiler denitrification flue gas ammonia slip detection system according to claim 3, characterized in that: The mass ratio of copper sulfate to potassium sodium tartrate is 1:

3.

5. A detection method for an ammonia detection system in boiler denitrification flue gas according to any one of claims 1-4, characterized in that: The method includes: Raw flue gas is extracted from the outlet flue of the denitrification system using a heated sampling probe and then divided into two streams: First path: Flue gas is introduced into a selective ammonia remover, which specifically adsorbs and removes all ammonia in the flue gas, but allows particulate matter to pass through without damage, and the output is the first standard sample S1; Second path: Direct bypass, no processing, output is the second standard sample S2; The first standard sample S1 and the second standard sample S2 were respectively introduced into two identical transparent reaction tanks, namely reaction tank A and reaction tank B. A copper ammonia complex colorimetric agent was injected into the two reaction tanks simultaneously and in equal amounts, and the colorimetric reaction was carried out under aerobic conditions. Starting from the injection of the copper ammonia complex chromogenic agent, a high-speed camera synchronously captures images of the two reaction cells at fixed time intervals until the reaction reaches the plateau phase, resulting in two sets of image sequences, Image-S1(t) and Image-S2(t); the shooting positions and shooting parameters of the two reaction cells are completely identical; Images from the image sequence showing the plateau phase of the response were selected to obtain two endpoint images, including Image-S1. final and Image-S2 final After pixel-level registration of the two endpoint images, the image Image-S3, which eliminates the apparent interference of particulate matter, is generated through the first image grayscale correction. Ammonia concentration characteristic parameters are extracted from Image-S3, including the average intensity Pc of the blue channel, the average saturation Ps of the image, and the standard deviation Pu of the image gray values. Based on the average intensity Pc of the blue channel, the average saturation Ps of the image, and the standard deviation Pu of the image gray values, the apparent ammonia escape index Ia is obtained through a weighted algorithm. The apparent ammonia escape index Ia is used to evaluate the intensity of the colorimetric reaction detected by the optical system under the current measurement conditions after eliminating the influence of particulate matter optical occlusion. Analyze the image sequence Image-S2(t) of the second standard sample S2, construct its color depth-time response curve, extract the maximum slope Vmr of the response curve and the time T90r required for the color depth to reach 90% of the final stable value from the baseline, and compare it with the preset ideal values ​​Vmi and T90i measured using pure standard ammonia in a calibrated particulate-free environment. Calculate the λ factor using the formula: λ=α* (Vmr / Vmi) +β* (T90 / T90r), where α and β are preset weights, α+β=1, and λ is the response validity verification factor. λ equals 1, indicating a normal response, and λ< 1, indicating an inhibited response. The apparent ammonia slip index Ia is corrected by the λ factor to compensate for the bias caused by chemical inhibition, and the final ammonia slip index If is obtained. The final ammonia slip index If is used to evaluate whether the actual ammonia slip concentration in the current flue gas exceeds the limit. If = Ia / λ, where If is the final ammonia escape index and Ia is the apparent ammonia escape index; Compare If with the threshold T. If If > T: ammonia escape exceeds the limit, triggering an alarm; if If ≤ T: normal. The threshold T is the standard ammonia gas with a concentration equal to the national statutory emission limit. The above steps are repeated to obtain the final ammonia escape index, which is set as the threshold T.

6. The method for detecting ammonia slip in boiler denitrification flue gas according to claim 5, characterized in that: After pixel-level registration of the two endpoint images, a first image grayscale correction is performed. This first image grayscale correction is achieved by executing Image-S3 = Image-S2. final - k*Image-S1 final Operation, Image-S3= Image-S2 final - k*Image-S1 final The calculation methods for operations include: Image-S1 final and Image-S2 final Converting the color image to grayscale results in two grayscale value matrices, G-S1(x, y) and G-S2(x, y), where (x, y) are pixel coordinates. The grayscale values ​​are normalized to the range [0, 1], where 0 represents black and 1 represents white. A custom background reference region is defined in the image; this region is the area without color development reaction, including the edge of the reaction cell. k is a dynamic coefficient, obtained as follows: Extract the grayscale values ​​from the background reference region in grayscale images G-S1(x, y) and G-S2(x, y). Assuming there are N pixels in the background reference region, take the average value: N gray values ​​are extracted from G-S1: [g1-s1, g2-s1, ..., gN-s1], mean-S1 = (g1-s1 + g2-s1 + ... + gN-s1) / N; where mean-S1 is the average gray value in the background reference area of ​​G-S1. N gray values ​​are extracted from G-S2: [g1-s2, g2-s2, ..., gN-s2]; mean-S2 = (g1-s2 + g2-s2 + ... + gN-s2) / N; where mean-S2 is the average gray value within the background reference region in G-S2; k = mean-S2 / mean-S1; Perform pixel-by-pixel difference, calculating for each pixel (x, y) in the grayscale images G-S1(x, y) and G-S2(x, y): G-S3(x, y) = G-S2(x, y) - k*G-S1(x, y), where G-S3(x, y) is the differenced grayscale matrix, which is then re-displayed as the image Image-S3.

Images