Denitration parameter continuous monitoring system and method based on single furnace and double flues

Abstract

The embodiment of the invention provides a denitration parameter continuous monitoring system and method based on single furnace and double flues, and belongs to the technical field of denitration. The system comprises grid method sampling devices which are independently arranged corresponding to all flues and are used for monitoring flue gas state parameters in the corresponding flues based on the working state at the current moment; wherein the working state at the current moment is polling sampling, mixed sampling or reverse blowing; at least one grid method sampling device in each flue is in a mixed sampling working state at the same moment; and the control device is used for obtaining the NOx concentration in each flue at the current moment based on the flue gas state parameters in each flue. According to the scheme, comprehensive and continuous monitoring of denitration parameters is ensured, the control accuracy of the ammonia spraying amount is improved, the risks that the ammonia escape rate is too high and the NOx concentration exceeds the standard are avoided, and the stability and the environmental protection effect of the system are improved.

Description

Technical Field

[0001] The invention relates to the technical field of denitration, and in particular to a denitration parameter continuous monitoring system based on a single furnace with two flues and a denitration parameter continuous monitoring method based on a single furnace with two flues. Background Art

[0002] In large coal-fired power plants, SCR (selective catalytic reduction) denitrification technology is a key measure to control NOx emissions. NH3 is used to reduce NOx in flue gas to harmless N2 and H2O to reduce environmental pollution. However, during the operation of the SCR system, accurate control of the amount of ammonia injection is particularly important. Excessive ammonia injection will cause ammonia escape, which may then deposit ammonium bisulfate in parts such as the air preheater, causing equipment blockage and corrosion, and affecting system stability. Therefore, how to measure the NOx concentration at the outlet of the SCR device in real time and accurately to guide ammonia injection control is an important technical problem in the denitrification system.

[0003] The existing technology usually adopts an online NOx concentration monitoring device to detect and feedback control the NOx concentration, among which the single-point sampling method is relatively simple and can provide real-time data of the NOx concentration at the flue outlet. However, single-point sampling is difficult to fully reflect the distribution of NOx concentration on the flue cross section, and cannot meet the needs of refined ammonia injection under deep peak regulation and multiple operating conditions. To this end, some systems have introduced a grid sampling device to measure the NOx concentration at different locations through patrol sampling at multiple sampling points to achieve zoned ammonia injection control. However, the sampling mode of this scheme cannot obtain the average NOx concentration value of the SCR denitrification outlet in real time during patrol sampling or backwash cleaning, which affects the overall control effect of the ammonia injection amount. In addition, the equipment will be blocked by particulate matter in the flue gas during long-term operation, further affecting the measurement accuracy and reliability of the sampling device.

[0004] In summary, the existing denitrification monitoring technology has certain shortcomings in multi-point patrol sampling and continuous monitoring. It is difficult to simultaneously achieve the requirements of continuous monitoring of global NOx concentration and zoned concentration measurement, especially under complex operating conditions and high-frequency peak-shaving requirements, the ammonia injection control accuracy is limited. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a system and method for continuous monitoring of denitrification parameters based on a single furnace and dual flues, so as to at least solve the problem that the existing denitrification monitoring technology has certain shortcomings in multi-point patrol sampling and continuous monitoring, and it is difficult to simultaneously achieve the requirements of continuous monitoring of global NOx concentration and zoned concentration measurement.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present invention provides a continuous monitoring system for denitrification parameters based on a single furnace and two flues, the system comprising: a grid sampling device separately arranged corresponding to each flue, for performing flue gas state parameter monitoring in the corresponding flue based on the working state at the current moment; wherein the working state at the current moment is patrol sampling, mixed sampling or backblowing; at least one grid sampling device in each flue is in a mixed sampling working state at the same time; and a control device, for obtaining the NOx concentration in each flue at the current moment based on the flue gas state parameters in each flue.

[0007] Optionally, the grid sampling device includes: a multi-point sampling gun installed in the flue for collecting flue gas samples at different positions; a sampling branch pipe connected to the multi-point sampling and used to transmit the flue gas collected from each sampling gun to the sampling main pipe; the sampling main pipe collects the flue gas samples from the sampling branches to obtain a sample flow; an instrument sampling pipe connected to the sampling main pipe and used to send the collected sample flow to the NOx concentration measuring instrument; the NOx concentration measuring instrument is installed on the sampling main pipe; an exhaust pipe connected to the sampling main pipe; Downstream of the sampling main pipe, it is used to discharge the sampled flue gas to the downstream flue or emission system; the gas source pipe is connected to the gas source inlet of the negative pressure generator, and is used to provide gas source to ensure the gas flow during sample collection and backblowing; the negative pressure generator is connected to the sampling main pipe and the exhaust pipe, and is used to inhale the flue gas sample by generating negative pressure, or to push the gas source to the exhaust pipe in the backblowing mode; the sampling switching valve is installed on the sampling branch pipe; the state control valve is installed on the exhaust pipe, and is used to control the working state switching in conjunction with the sampling switching valve.

[0008] Optionally, the control rules for switching the working states of the state control valve and the sampling switching valve are as follows: when the state control valve is closed, the sampling switching valve is opened in a patrolling manner, and the working state of the corresponding grid method sampling device is a backflush state; when the state control valve is opened, the sampling switching valves are all opened, and the working state of the corresponding grid method sampling device is a mixed sampling state; when the state control valve is opened, the sampling switching valve is opened in a patrolling manner, and the working state of the corresponding grid method sampling device is a patrol sampling state.

[0009] Optionally, the multi-point sampling gun, the sampling branch pipe and the sampling switching valve are provided in plurality and correspond one to one to each other.

[0010] Optionally, each grid sampling device is executed cyclically between each working state based on a fixed time table, and between each cycle, the switching sequence between each working state and the duration of each corresponding working state are the same; the grid sampling device separately set for each flue includes a grid sampling device for the flue on the A side and a grid sampling device for the B side. Both pipes lead the flue gas from the flue at the outlet of the boiler economizer.

[0011] Optionally, the switching order between the working states of each grid sampling device between each cycle is: mixed sampling on both sides A and B - mixed sampling on side A, patrol sampling on side B - mixed sampling on both sides A and B - patrol sampling on side A, mixed sampling on side B - mixed sampling on both sides A and B - mixed sampling on side A, backflush on side B - mixed sampling on both sides A and B - backflush on side A, mixed sampling on side B.

[0012] Optionally, the control device is configured as follows: if the grid sampling device of the flue on side A and the grid sampling device of the flue on side B are both in a mixed sampling working state, then the NOx concentration of the flue on side A is the NOx concentration collection value of the grid sampling device of the flue on side A, and the NOx concentration of the flue on side B corresponds to the NOx concentration collection value of the grid sampling device of the flue on side B; if the grid sampling device of the flue on side A and the grid sampling device of the flue on side B are not both in a mixed sampling working state, then the NOx concentration of the flue corresponding to the grid sampling device in the mixed sampling working state is the NOx concentration collection value of the corresponding grid sampling device, and the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline.

[0013] Optionally, the flue gas state parameters include: the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the current moment, the NOx concentration collection value of the grid sampling device in the non-mixed sampling working state at the most recent time when it was cut out of the mixed sampling working state, the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the same time as the grid sampling device in the non-mixed sampling working state when it was cut out of the mixed sampling working state, and the real-time total ammonia injection flow of each flue at the current moment; the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline, and the corresponding calculation rule is:

[0014] in, The NOx concentration in the flue corresponding to the grid sampling device in the non-mixed sampling working state; It is the NOx concentration collection value of the grid sampling device in the non-mixed sampling working state at the most recent time it was switched out of the mixed sampling working state; is the total ammonia injection flow rate of the flue corresponding to the grid sampling device that is in the mixed sampling working state at the current moment; is the total ammonia injection flow rate of the flue corresponding to the grid sampling device which is in the non-mixed sampling working state at the current moment; It is the NOx concentration collection value of the grid sampling device which is in the mixed sampling working state at the current moment; It is the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the same time as the grid sampling device in the non-mixed sampling working state was cut out from the mixed sampling working state most recently.

[0015] The second aspect of the present invention provides a method for continuous monitoring of denitrification parameters based on a single furnace with two flues. The method is implemented based on the above-mentioned continuous monitoring system for denitrification parameters based on a single furnace with two flues. The method includes: collecting flue gas state parameters in the corresponding flue based on a grid sampling device separately arranged in each flue; determining the NOx concentration determination rule of each flue based on the current working state of each grid sampling device; wherein the grid sampling device separately arranged in each flue includes a grid sampling device for the flue on the A side and a grid sampling device for the flue on the B side; if the grid sampling device for the flue on the A side and the grid sampling device for the flue on the B side are both in a mixed sampling working state, then the grid sampling device for the flue on the A side The NOx concentration is the NOx concentration collection value of the grid sampling device of the flue on side A, and the NOx concentration of the flue on side B corresponds to the NOx concentration collection value of the grid sampling device of the flue on side B; if the grid sampling device of the flue on side A and the grid sampling device of the flue on side B are not both in the mixed sampling working state, then the NOx concentration of the flue corresponding to the grid sampling device in the mixed sampling working state is the NOx concentration collection value of the corresponding grid sampling device, and the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline; based on the NOx concentration determination rule of each flue and based on the flue gas state parameters in each flue, the NOx concentration in each flue at the current moment is obtained.

[0016] On the other hand, the present invention provides a computer-readable storage medium having instructions stored thereon, which, when executed on a computer, enables the computer to execute the above-mentioned method for continuous monitoring of denitrification parameters based on a single furnace and dual flues.

[0017] Through the above technical scheme, the present invention is based on the continuous monitoring system of denitrification parameters of a single furnace with two flues. Through the grid sampling device independently set in the double flues, it works alternately in patrol sampling, mixed sampling or back-blowing mode at different times, effectively realizing the continuous monitoring of NOx concentration in each flue. The system ensures that the sampling device of at least one flue is in a mixed sampling state at any time, so that the average NOx concentration on both sides can be obtained in real time. Even when the sampling device of one flue is in patrol or back-blowing mode, the concentration data on the other side can be obtained by calculation. This design ensures comprehensive and continuous monitoring of denitrification parameters, improves the control accuracy of the ammonia injection amount, avoids the risk of excessive ammonia escape rate and excessive NOx concentration, and improves the stability and environmental protection effect of the system. Through the reasonable configuration of this sampling mode, the system can continuously provide high-precision NOx monitoring results under complex working conditions.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a system structure diagram of a denitration parameter continuous monitoring system based on a single furnace and dual flues provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of the layout of a double flue denitrification system provided by one embodiment of the present invention; Figure 3 An embodiment of the present invention provides Figure 2 AA cross-section diagram in the figure; Figure 4 It is a schematic diagram of a device of a continuous monitoring system of denitration parameters based on a single furnace and dual flues provided by an embodiment of the present invention; Figure 5 An embodiment of the present invention provides Figure 4 AA view in the figure; Figure 6 is a schematic diagram of a working state switching rule provided by an embodiment of the present invention; Figure 7 It is a flowchart of the steps of a method for continuous monitoring of denitrification parameters based on a single furnace with two flues provided in one embodiment of the present invention.

[0020] Description of Reference Numerals 1- boiler economizer outlet flue; 2- SCR inlet flue; 3- SCR outlet flue; 4- SCR device; 5- multi-point sampling gun; 6- sampling branch pipe; 7- sampling main pipe; 8- instrument sampling pipe; 9- exhaust pipe; 10- gas source pipe; 11- negative pressure generator; 12- sampling switching valve; 13- state control valve; 14- NOx concentration measuring instrument. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0022] Figure 1 1 is a system structure diagram of a denitration parameter continuous monitoring system based on a single furnace and dual flues provided by an embodiment of the present invention. Figure 1As shown, an embodiment of the present invention provides a denitrification parameter continuous monitoring system based on a single furnace and two flues, the system comprising: a grid sampling device separately arranged corresponding to each flue, for performing flue gas state parameter monitoring in the corresponding flue based on the working state at the current moment; wherein the working state at the current moment is patrol sampling, mixed sampling or backwashing; at least one grid sampling device in each flue is in a mixed sampling working state at the same time; a control device, for obtaining the NOx concentration in each flue at the current moment based on the flue gas state parameters in each flue.

[0023] In the embodiment of the present invention, the specific rules for each working state are: 1) Mixed sampling: In the mixed mode, all sampling ports of the sampling device are opened at the same time to collect flue gas samples from the entire flue cross section, so that the flue gas in the sampling mother pipe 7 is fully mixed to form a highly representative average flue gas sample. In this mode, the average NOx concentration of the flue can be obtained in real time, which is suitable for continuous monitoring of the overall NOx concentration and is a key mode for precise control of the ammonia injection amount.

[0024] 2) Patrol sampling: The patrol mode is to collect local flue gas samples by opening sampling ports at different positions in turn, so as to measure the distributed NOx concentration of the flue cross section one by one. This mode can identify the NOx concentration distribution at different positions, which helps to adjust the ammonia injection amount in different zones to ensure the uniformity of ammonia injection.

[0025] 3) Backflush: The backflush mode is to blow high-pressure gas out of the sampling device in the opposite direction by closing the state control valve 13 and opening the backflush gas source to clean the sampling channel. This mode is used to prevent the sampling device from being blocked by dust or pollutants, keep the sampling channel unobstructed, and extend the service life of the sampling device.

[0026] Preferably, Figure 2 , a schematic diagram of the layout of a double-flue denitrification system is provided, in which each pipe is led out through the boiler economizer outlet flue 1, and the corresponding SCR inlet flue 2 and SCR outlet flue 3 are both double pipes, and the boiler economizer outlet is introduced into the SCR device 4 through the pipe. Figure 3 is the AA cross-section. Figure 5 and Figure 6As shown, the grid sampling device includes: a multi-point sampling gun 5, installed in the flue, used to collect flue gas samples at different positions; a sampling branch pipe 6, connected to the multi-point sampling, used to transmit the flue gas collected from each sampling gun to the sampling main pipe 7; the sampling main pipe 7 collects the flue gas samples from the sampling branch pipe 6 to obtain a sample flow; an instrument sampling pipe 8, connected to the sampling main pipe 7, used to send the collected sample flow to the NOx concentration measuring instrument 14; the NOx concentration measuring instrument 14 is installed on the sampling main pipe 7; an exhaust pipe 9, connected to the sampling main pipe 7; Downstream of the main pipe 7, it is used to discharge the sampled flue gas to the downstream flue or exhaust system; the gas source pipe 10 is connected to the gas source inlet of the negative pressure generator 11, and is used to provide gas source to ensure the gas flow during sample collection and backblowing; the negative pressure generator 11 is connected to the sampling main pipe 7 and the exhaust pipe 9, and is used to inhale the flue gas sample by generating negative pressure, or to push the gas source to the exhaust pipe 9 in the backblowing mode; the sampling switching valve 12 is installed on the sampling branch pipe 6; the state control valve 13 is installed on the exhaust pipe 9, and is used to control the working state switching in conjunction with the sampling switching valve 12.

[0027] In the embodiment of the present invention, a multi-point sampling gun 5 is included, which is installed at different positions in the flue to ensure that the flue gas at multiple representative sample points is collected from the cross section of the flue gas flow. The multi-point sampling gun 5 is connected to the sampling main pipe 7 through the sampling branch pipe 6. Each branch pipe independently collects the flue gas sample and transmits it to the main pipe, so that the samples of each sampling point can be collected to generate a representative sample flow. Such a design makes it possible to obtain a comprehensive NOx concentration that truly reflects the entire flue gas flow regardless of how the flue gas flow changes.

[0028] The sampling main pipe 7 transmits these collected flue gas samples to the NOx concentration measuring instrument 14, and connects them through the instrument sampling pipe 8 to ensure the continuous transmission of the sample flow. The NOx concentration measuring instrument 14 is installed on the sampling main pipe 7 to detect the NOx concentration of the sample in real time and provide feedback for the ammonia injection control. The exhaust pipe 9 is located downstream of the sampling main pipe 7, and discharges the measured flue gas to the downstream flue or emission system to avoid sample retention, thereby preventing sample accumulation from affecting the subsequent measurement accuracy.

[0029] In order to ensure the stability of sampling and back-blowing operations, the system is designed with a gas source tube 10 and a negative pressure generator 11. The gas source tube 10 is connected to the gas source inlet of the negative pressure generator 11 to provide pressure support for gas flow during the sample collection process, avoiding pipeline blockage and poor sampling. The negative pressure generator 11 is connected to the sampling main tube 7 and the exhaust pipe 9, and can generate negative pressure to inhale the flue gas sample. In addition, in the back-blowing mode, the negative pressure generator 11 pushes the gas source to the exhaust pipe 9 to remove residual particles and impurities in the sampling channel, ensuring the cleanliness of the sampling device and the continuity of sampling.

[0030] The design of the sampling switching valve 12 and the state control valve 13 further improves the function of the device. The sampling switching valve 12 is installed on the sampling branch pipe 6, responsible for controlling the switching of the sampling branch pipe 6 between patrol, mixing or backwashing modes, so as to realize flexible selection of different sampling states. The state control valve 13 is installed on the exhaust pipe 9, and is used in conjunction with the sampling switching valve 12 to switch freely between different sampling modes. This combined control design improves the flexibility and accuracy of the entire system, and ensures that the continuous monitoring of NOx concentration can be carried out flexibly and efficiently under complex working conditions.

[0031] Preferably, the control rules for switching the working states of the state control valve 13 and the sampling switching valve 12 are as follows: when the state control valve 13 is closed, the sampling switching valve 12 is opened in a patrolling manner, and the working state of the corresponding grid method sampling device is a backflush state; when the state control valve 13 is opened, the sampling switching valve 12 is fully opened, and the working state of the corresponding grid method sampling device is a mixed sampling state; when the state control valve 13 is opened, the sampling switching valve 12 is opened in a patrolling manner, and the working state of the corresponding grid method sampling device is a patrol sampling state.

[0032] In the embodiment of the present invention, when the state control valve 13 is closed and the sampling switching valve 12 is opened in a patrol, the grid method sampling device enters the backflush state. In this state, the system closes the state control valve 13 and opens the specific sampling switching valve 12, so that the high-pressure gas is blown back into the sampling channel, thereby removing the dust and impurities in the sampling pipeline. This function effectively prevents the sampling device from being blocked due to the accumulation of particulate matter after long-term operation, and improves the patency of the sampling channel and the durability of the device.

[0033] When the state control valve 13 is open and the sampling switching valves 12 are all open, the system enters the mixed sampling state. In this state, the sampling channels of all sampling points remain open, collecting and gathering flue gas at different positions of the flue to form a uniform sample flow. The flue gas samples collected in this mode represent the overall NOx concentration on the flue cross section, which can be used to monitor the average NOx emission level of the entire flue in real time, providing stable and reliable data for the precise control of the ammonia injection amount.

[0034] When the state control valve 13 is open and the sampling switching valve 12 is opened in a patrol mode, the system enters the patrol sampling state. In the patrol mode, the system collects local flue gas samples at different locations by opening the switching valves of different sampling points in turn, and detects the NOx concentration distribution in the flue one by one. This mode can provide accurate partition data, which helps to adjust the ammonia injection amount according to the actual NOx distribution, ensure the uniformity of ammonia injection and the overall effect of denitrification.

[0035] Preferably, the multi-point sampling gun 5, the sampling branch pipe 6 and the sampling switching valve 12 are provided in plurality and correspond to each other one by one.

[0036] In an embodiment of the present invention, a plurality of multi-point sampling guns 5, sampling branches 6 and sampling switching valves 12 are arranged in one-to-one correspondence with each other, and the number is more than three. This multi-point setting design enables the sampling system to collect flue gas samples at different positions in the flue more comprehensively, and the one-to-one corresponding structure ensures the independence of the sampling path and avoids interference between different sampling channels. The multi-point sampling guns 5 are evenly distributed at different positions in the flue, and combined with the sampling branches 6 and the corresponding sampling switching valves 12, independent sampling and partition monitoring are achieved. Each sampling gun is connected to a specific branch and switching valve. This configuration allows the system to transmit the samples collected at each sampling point to the NOx concentration measurement device separately, ensuring the accuracy and interference-free sample transmission process at each position.

[0037] The arrangement of more than three points of the multi-point sampling gun 5 can more comprehensively cover different areas on the entire flue cross section. By setting more than three sampling points, the system can obtain the NOx concentration distribution information of different areas in the flue in real time, so as to more accurately reflect the concentration distribution of the flue gas and provide the system with high-resolution monitoring data. This multi-point sampling can achieve more accurate zoned ammonia spray control and improve the NOx reduction efficiency. In addition, the design of the sampling switching valve 12 enables the system to flexibly open the sampling channels of each sampling point one by one in the patrol mode, thereby ensuring the sampling frequency and response speed of the system. If the system is in mixed sampling mode, all sampling points can be opened at the same time to obtain the average concentration data of the flue cross section to achieve comprehensive concentration monitoring needs.

[0038] Based on the scheme of the present invention, through the multi-group settings and one-to-one corresponding layout of the multi-point sampling gun 5, the sampling branch pipe 6 and the sampling switching valve 12, the system achieves higher sampling accuracy and data reliability, and solves the problems of data distortion and regional monitoring blind spots in the traditional single-point sampling mode. This design not only enables the sampling system to respond flexibly in both patrol and mixed modes, but also improves the measurement accuracy of NOx concentration in the flue cross section. With the help of multi-point sampling and partition monitoring, the system can adjust the amount of ammonia sprayed in different areas in real time to achieve a more uniform ammonia distribution, thereby reducing ammonia escape and optimizing the denitrification effect. Overall, this arrangement effectively improves the control accuracy and response speed of the SCR denitrification system. While achieving precise denitrification, it also reduces the system maintenance requirements and enhances the long-term stability and environmental protection efficiency of the denitrification system.

[0039] Preferably, each grid sampling device cycles between each working state based on a fixed timing table, and between each cycle, the switching order between the working states and the duration of each corresponding working state are the same; the grid sampling device separately arranged for each flue includes a grid sampling device for the flue on the A side and a grid sampling device on the B side.

[0040] Further, such as Figure 6 Between each cycle, the switching order between the working states of each grid sampling device is: mixed sampling on both sides A and B-mixed sampling on side A, patrol sampling on side B-mixed sampling on both sides A and B-patrol sampling on side A, mixed sampling on side B-mixed sampling on both sides A and B-mixed sampling on side A, backflush on side B-mixed sampling on both sides A and B-backflush on side A, mixed sampling on side B.

[0041] In the embodiment of the present invention, the grid sampling devices on both sides A and B are executed according to the preset cycle sequence and schedule, and the switching of mixed sampling, round sampling and backwashing is completed in sequence in one cycle. The order and duration of each cycle are consistent to ensure the stability and continuity of data collection in different sampling modes of the system. The timing table of the sampling mode accurately arranges the switching order and time length of each state, which can realize the automation and balanced control of the denitrification system under complex working conditions.

[0042] In detail, the system puts both sides A and B in mixed sampling mode for a fixed time, for example, overall sampling is performed every 50 minutes to ensure uniform data collection of NOx concentration in the flue. This mixed sampling state provides a global average concentration value, which provides a solid foundation for the precise control of the total amount of ammonia injection. In the next 5 minutes, the system switches to a mode of mixed sampling on the A side and patrol sampling on the B side, gradually collecting NOx concentrations in different areas of the B side. Then, the system returns to the mixed sampling state again to obtain the overall average concentration again and confirm the ammonia injection control effect. After that, the A side and the B side switch between patrol and backflush modes in turn, with patrol sampling on the B side, mixed sampling on the A side, backflush on the A side, mixed sampling on the B side, etc. The entire cycle is repeated between 50 minutes of mixed sampling and 5 minutes of switching states.

[0043] This strict timing cycle design has significant technical effects. First, the mixed sampling occupies a longer period of time (50 minutes) in the cycle, ensuring continuous monitoring of NOx concentration in the entire system and avoiding data fluctuations caused by local sampling. In addition, patrol sampling provides partitioned concentration data, which helps to discover and correct NOx concentration differences in each area, thereby optimizing the uniformity of ammonia injection. The backflush mode ensures the cleanliness of the sampling pipeline, avoiding measurement deviations caused by blockage due to dust accumulation or other pollutants, thereby improving the reliability and durability of the device.

[0044] In one possible implementation, assuming that the SCR system of a power station is operating at high load, the NOx concentration in the flue will fluctuate at different locations, with higher concentrations in some areas and lower concentrations in other areas. If the system relies only on a single mixed sampling mode, this local concentration difference may be ignored, resulting in insufficient or excessive control of the amount of ammonia sprayed, affecting the NOx reduction efficiency and increasing the risk of ammonia escape. Through the design of the current grid sampling device, the system can obtain the overall average NOx concentration in a 50-minute mixed sampling state to ensure accurate control of the overall ammonia spray amount. In the next 5 minutes, through patrol sampling, the system samples the data of high-concentration areas one by one, and makes dynamic adjustments to ensure that the amount of ammonia sprayed accurately matches the actual demand. The backflush mode removes particulate matter in the pipeline to prevent dust accumulation from affecting the sampling efficiency under high load.

[0045] Based on the scheme of the present invention, the design of this time table significantly improves the monitoring accuracy and response speed of the SCR denitrification system, and realizes accurate control of the ammonia injection amount. The system can stably control the NOx concentration within 38±3 mg / Nm³ and effectively limit the ammonia escape rate to less than 1.2 ppm. Through high-frequency patrol sampling, the system promptly identifies and responds to possible concentration differences in the flue to ensure the uniformity of ammonia injection. The periodic cleaning of the backflush mode further extends the service life of the sampling device and reduces the frequency of shutdown maintenance. Against the background of increasingly stringent environmental protection requirements, this solution significantly reduces NOx emissions, improves the operating efficiency and stability of the SCR denitrification system, and provides a reliable and accurate NOx concentration monitoring and control solution for coal-fired power plants.

[0046] Preferably, the control device is configured as follows: if the grid sampling device of the flue on side A and the grid sampling device of the flue on side B are both in a mixed sampling working state, the NOx concentration of the flue on side A is the NOx concentration collection value of the grid sampling device of the flue on side A, and the NOx concentration of the flue on side B corresponds to the NOx concentration collection value of the grid sampling device of the flue on side B; if the grid sampling device of the flue on side A and the grid sampling device of the flue on side B are not both in a mixed sampling working state, the NOx concentration of the flue corresponding to the grid sampling device in the mixed sampling working state is the NOx concentration collection value of the corresponding grid sampling device, and the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline.

[0047] Further, the flue gas state parameters include: the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the current moment, the NOx concentration collection value of the grid sampling device in the non-mixed sampling working state at the time when it was cut out from the mixed sampling working state most recently, the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the same time as the grid sampling device in the non-mixed sampling working state at the time when it was cut out from the mixed sampling working state most recently, and the real-time total ammonia injection flow of each flue at the current moment; the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline, and the corresponding calculation rule is:

[0048] in, The NOx concentration in the flue corresponding to the grid sampling device in the non-mixed sampling working state; It is the NOx concentration collection value of the grid sampling device in the non-mixed sampling working state at the most recent time it was switched out of the mixed sampling working state; is the total ammonia injection flow rate of the flue corresponding to the grid sampling device that is in the mixed sampling working state at the current moment; is the total ammonia injection flow rate of the flue corresponding to the grid sampling device which is in the non-mixed sampling working state at the current moment; It is the NOx concentration collection value of the grid sampling device which is in the mixed sampling working state at the current moment; It is the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the same time as the grid sampling device in the non-mixed sampling working state was cut out from the mixed sampling working state most recently.

[0049] Based on the scheme of the present invention, when the grid sampling devices on the A side and the B side are both in the mixed sampling state, the system can directly use the NOx concentration collection values ​​on both sides as the NOx concentration of each flue, which realizes direct and accurate monitoring of the NOx concentration, and the data reliability is high. However, if the sampling devices on the A side or the B side are not both in the mixed sampling state (for example, one side is in the mixed sampling state, and the other side is in the patrol or backwash state), the control device starts the corresponding calculation algorithm, and calculates the NOx concentration on the non-mixed sampling side by combining the real-time NOx concentration collection value on the mixed sampling side with the corresponding parameters.

[0050] The specific calculation process is as follows: Assume that the flue gas on side A is in a mixed sampling state and on side B is in a non-mixed sampling state. The control device will record the time point when the side B is most recently switched from a mixed sampling state to a non-mixed sampling state (such as patrol or backwash), and obtain the NOx concentration measurement values ​​on the A side and the B side at that moment (recorded as m and n, respectively).

[0051] Furthermore, when both sides A and B are in a mixed sampling state, the system can directly read the NOx concentration value without additional calculation, ensuring the real-time and accuracy of the data. Secondly, when one side is in a non-mixed sampling state, the control device calculates through a mapping formula to make up for the shortcomings of direct sampling on the other side and ensure the continuity of NOx concentration on both sides. In this way, no matter whether the system is in a mixed, patrol or backflush mode, it can maintain real-time monitoring and accurate calculation of NOx concentration, providing reliable data support for the precise control of the amount of ammonia injection. In addition, this solution avoids the decline in overall monitoring accuracy due to unilateral data interruption, greatly improving the stability and environmental adaptability of the system.

[0052] Comparative example: If only one side is in the mixed sampling state, the real-time value of the average NOx concentration at the denitration outlet on the other side is the measured value of the NOx concentration measuring instrument 14 at the last mixed state on this side (i.e., data retention is performed when in the backflush state or patrol sampling state). Because the other side failed to continuously obtain the accurate average NOx concentration at the denitration outlet, affected by load fluctuations, the NOx emission concentration was (38±15) mg / Nm3, and the maximum value exceeded the environmental protection allowed 50mg / Nm3. When the NOx emission concentration was lower than 25mg / Nm3, the corresponding ammonia escape rate exceeded 2.5ppm.

[0053] Figure 7 1 is a method flow chart of a method for continuous monitoring of denitration parameters based on a single furnace and dual flues provided by an embodiment of the present invention. Figure 7 As shown, an embodiment of the present invention provides a method for continuous monitoring of denitration parameters based on a single furnace with two flues, the method comprising: Step S10: collecting the flue gas state parameters in the corresponding flue based on the grid sampling device separately arranged in each flue.

[0054] Step S20: determining the NOx concentration determination rule of each flue based on the current working status of each grid sampling device.

[0055] Step S30: Based on the NOx concentration determination rule of each flue and based on the flue gas state parameters in each flue, the NOx concentration in each flue at the current moment is obtained.

[0056] The embodiment of the present invention further provides a computer-readable storage medium, on which instructions are stored, which, when executed on a computer, enable the computer to execute the above-mentioned method for continuous monitoring of denitrification parameters based on a single furnace and dual flues.

[0057] Those skilled in the art will understand that all or part of the steps in the method for implementing the above-mentioned embodiments can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a single-chip microcomputer, a chip or a processor execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0058] The optional embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, the technical scheme of the embodiments of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0059] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A continuous monitoring system for denitrification parameters based on a single furnace and dual flues, characterized in that: The system comprises: A grid sampling device is separately provided for each flue, and is used to monitor the flue gas state parameters in the corresponding flue based on the current working state; wherein, The current working status is patrol sampling, mixed sampling or backflushing; At least one of the grid sampling devices in each flue is in a mixed sampling working state at the same time; The control device is used to obtain the NOx concentration in each flue at the current moment based on the flue gas state parameters in each flue.

2. The system according to claim 1, characterized in that The grid method sampling device comprises: Multi-point sampling gun, installed in the flue, used to collect flue gas samples at different locations; The sampling branch pipe is connected to the multi-point sampling and is used to transmit the flue gas collected from each sampling gun to the sampling main pipe; The sampling main pipe collects the flue gas samples from the sampling branch pipes to obtain a sample flow; An instrument sampling pipe connected to the sampling main pipe and used to send the collected sample flow into the NOx concentration measuring instrument; The NOx concentration measuring instrument is installed on the sampling main pipe; An exhaust pipe, connected downstream of the sampling main pipe, is used to discharge the sampled flue gas to a downstream flue or an exhaust system; A gas source tube connected to the gas source inlet of the negative pressure generator, used to provide a gas source to ensure gas flow during sample collection and backwashing; A negative pressure generator is connected to the sampling main pipe and the exhaust pipe, and is used to inhale the flue gas sample by generating negative pressure, or to push the gas source to the exhaust pipe in the back-blowing mode; The sampling switching valve is installed on the sampling branch pipe; The state control valve is installed on the exhaust pipe and is used to control the switching of the working state in conjunction with the sampling switching valve.

3. The system according to claim 2, characterized in that The control rules for the state control valve and the sampling switching valve to switch the working state are: When the state control valve is closed, the sampling switching valve is opened in a patrol mode, and the corresponding working state of the grid sampling device is the backflush state; When the state control valve is open and the sampling switching valves are all open, the corresponding working state of the grid sampling device is the mixed sampling state; When the state control valve is opened, the sampling switching valve is opened in a patrol mode, and the corresponding working state of the grid sampling device is a patrol sampling state.

4. The system according to claim 2, characterized in that The multi-point sampling gun, the sampling branch pipe and the sampling switching valve are all provided in plurality and correspond to each other one by one.

5. The system according to claim 1, characterized in that Each grid sampling device is executed cyclically between each working state based on a fixed timing table. Between each cycle, the switching order between each working state and the duration of each working state are the same; The grid sampling device independently arranged for each flue comprises a grid sampling device for the flue on the A side and a grid sampling device for the flue on the B side.

6. The system according to claim 5, characterized in that The switching order between the working states of each grid sampling device between each cycle is as follows: Mixed sampling on both sides A and B - Mixed sampling on side A and patrol sampling on side B - Mixed sampling on both sides A and B - Patrol sampling on side A and mixed sampling on side B - Mixed sampling on both sides A and B - Mixed sampling on side A and backflush on side B - Mixed sampling on both sides A and B - Backflush on side A and mixed sampling on side B.

7. The system according to claim 5, characterized in that The control device is configured to: If the grid sampling device of the flue on the A side and the grid sampling device of the flue on the B side are both in the mixed sampling working state, the NOx concentration of the flue on the A side is the NOx concentration collection value of the grid sampling device of the flue on the A side, and the NOx concentration of the flue on the B side corresponds to the NOx concentration collection value of the grid sampling device of the flue on the B side; If the grid sampling device of the flue on side A and the grid sampling device of the flue on side B are not both in the mixed sampling working state, the NOx concentration of the flue corresponding to the grid sampling device in the mixed sampling working state is the NOx concentration collection value of the corresponding grid sampling device, and the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline.

8. The system according to claim 7, characterized in that Flue gas state parameters include: The NOx concentration collection value of the grid sampling device in the mixed sampling working state at the current moment, the NOx concentration collection value of the grid sampling device in the non-mixed sampling working state at the time when it was last switched out of the mixed sampling working state, the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the same time as the time when the grid sampling device in the non-mixed sampling working state was last switched out of the mixed sampling working state, and the real-time total ammonia injection flow rate of each flue at the current moment; The NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline, and the corresponding calculation rule is: in, The NOx concentration in the flue corresponding to the grid sampling device in the non-mixed sampling working state; It is the NOx concentration collection value of the grid sampling device in the non-mixed sampling working state at the most recent time it was switched out of the mixed sampling working state; is the total ammonia injection flow rate of the flue corresponding to the grid sampling device that is in the mixed sampling working state at the current moment; is the total ammonia injection flow rate of the flue corresponding to the grid sampling device which is in the non-mixed sampling working state at the current moment; It is the NOx concentration collection value of the grid sampling device which is in the mixed sampling working state at the current moment; It is the NOx concentration collection value of the grid sampling device in the mixed sampling working state at the same time as the grid sampling device in the non-mixed sampling working state was cut out from the mixed sampling working state most recently.

9. A method for continuous monitoring of denitrification parameters based on a single furnace with two flues, characterized in that: The method is implemented based on the denitration parameter continuous monitoring system based on a single furnace and dual flues according to any one of claims 1 to 8, and the method comprises: The grid sampling device separately arranged in each flue collects the flue gas state parameters in the corresponding flue; The NOx concentration determination rule of each flue is determined based on the current working state of each grid sampling device; wherein, The grid sampling device independently provided for each flue includes a grid sampling device for the flue on the A side and a grid sampling device for the flue on the B side; If the grid sampling device of the flue on the A side and the grid sampling device of the flue on the B side are both in the mixed sampling working state, the NOx concentration of the flue on the A side is the NOx concentration collection value of the grid sampling device of the flue on the A side, and the NOx concentration of the flue on the B side corresponds to the NOx concentration collection value of the grid sampling device of the flue on the B side; If the grid sampling device of the flue on the A side and the grid sampling device of the flue on the B side are not both in the mixed sampling working state, the NOx concentration of the flue corresponding to the grid sampling device in the mixed sampling working state is the NOx concentration collection value of the corresponding grid sampling device, and the NOx concentration of the flue on the other side is obtained by calculating the flue gas state parameters of each pipeline; Based on the NOx concentration determination rule of each flue and the flue gas state parameters in each flue, the NOx concentration in each flue at the current moment is obtained.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, which, when executed on a computer, enable the computer to execute the method for continuous monitoring of denitrification parameters based on a single furnace and dual flues as described in claim 9.

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