Dilution method-based CO2 high-precision measurement and analysis system and method for thermal power plant

Abstract

The embodiment of the invention provides a dilution method-based CO2 high-precision measurement and analysis system and method for a thermal power plant, and the system comprises a sampling probe which is used for intercepting original flue gas; the heat tracing conduit is sleeved on the sampling probe; the constant temperature device is connected with the rear end of the sampling probe; the fine filter is connected with the constant temperature device; the sample gas mass flow controller is connected with the fine filter, the diluted gas source steel cylinder and the mixing chamber and is used for accurately controlling the flow of the filtered original flue gas and diluted gas entering the mixing chamber by adopting a thermal principle; the diluted gas source steel cylinder is connected with the sample gas mass flow controller; the mixing chamber is connected with the sample gas mass flow controller; the analyzer is used for detecting the concentration of CO2 in the diluted flue gas; the sampling pump is connected with the mixing chamber and located at the tail end of the system; the central controller is used for controlling cooperative work of all parts in the CO2 high-precision measurement and analysis system based on the control instruction; and the human-computer interface module is connected with the central controller and the analyzer.

Description

Technical Field

[0001] This document relates to the field of computer technology, and in particular to a high-precision CO2 measurement and analysis system and method for thermal power plants based on the dilution method. Background Technology

[0002] With the increasingly severe global climate change problem, controlling greenhouse gas emissions, especially CO2 emissions, has become an international consensus. As one of the major sources of CO2 emissions, accurate and real-time monitoring of carbon emissions from thermal power plants is crucial. This is not only the foundation for meeting national and international environmental regulations and participating in the carbon emissions trading market, but also a prerequisite for power plants to optimize energy efficiency and evaluate and implement carbon capture, utilization, and storage technologies. Therefore, high-precision and high-reliability continuous online monitoring of CO2 concentration in flue gas from thermal power plants has significant economic, environmental, and social implications.

[0003] Flue gas from thermal power plants is characterized by its complex composition and harsh conditions. Typical features include high dust content, high humidity, high temperature, and high CO2 concentration. Non-dispersive infrared (NDIR) gas analyzers are the mainstream technology for measuring CO2. However, when measuring high concentrations of CO2 in thermal power plant flue gas, the traditional direct extraction-pretreatment-NDIR measurement method faces significant challenges, such as limited measurement accuracy, heavy pretreatment burden, and high maintenance requirements.

[0004] Current online CO2 measurement systems in thermal power plants (especially those requiring high precision) have the following main drawbacks: (1) Insufficient accuracy of direct measurement of high concentration CO2: Existing systems that directly use NDIR analyzers to measure undiluted high concentration power plant flue gas have inherent nonlinear effects and saturation effects in the high concentration range that are difficult to completely compensate for, resulting in the absolute measurement accuracy and long-term stability being difficult to meet the high requirements of accurate carbon emission measurement. (2) Poor accuracy and stability of dilution ratio: The accuracy, repeatability, and long-term stability of the dilution ratio are the core challenges of some existing dilution systems. The flow controllers of the sample gas and dilution gas cannot maintain high accuracy and fast response under the complex and variable sample gas conditions (pressure, temperature, component fluctuations) in power plants, resulting in dilution ratio drift, which directly affects the final concentration calculation results. If the mixing chamber is poorly designed, the sample gas and dilution gas cannot achieve sufficient, rapid, and uniform mixing, which will lead to fluctuations in the sample gas concentration received by the analyzer and unstable measurement results; (3) Low system integration and intelligence: Existing systems often have independent operation of each component, lacking a powerful central controller for global coordination, parameter optimization, fault diagnosis and adaptive adjustment. In addition, the interface is not user-friendly, and functions such as parameter setting, status monitoring, historical data query and alarm management are scattered or rudimentary, which is not conducive to efficient use and maintenance by operators. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision CO2 measurement and analysis system and method for thermal power plants based on the dilution method, aiming to solve the above-mentioned problems in the prior art.

[0006] This invention provides a high-precision CO2 measurement and analysis system for thermal power plants based on the dilution method, comprising: A sampling probe is used to insert into the flue to capture raw flue gas; A heat tracing conduit is fitted around the sampling probe to provide constant temperature heat tracing for the sampling probe throughout its entire process, preventing water vapor condensation and acid corrosion. A constant temperature device, connected to the rear end of the sampling probe, is located outside the flue and is used to heat the flue gas during the flue gas transmission process; A fine filter, connected to a thermostat, is used to remove residual aerosols and dust from the cooled raw flue gas through the filter element; A sample gas mass flow controller, connected to the fine filter, dilution gas source cylinder, and mixing chamber, is used to precisely control the flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber using a thermal principle. A dilution gas source cylinder is connected to the sample gas mass flow controller for storing and outputting dilution gas; The mixing chamber, connected to the sample gas mass flow controller, is used to perform turbulent mixing of the filtered raw flue gas and the dilution gas through a cylindrical cavity and a spiral guide vane to obtain diluted flue gas. An analyzer, connected to the mixing chamber, is used to detect the CO2 concentration in the diluted flue gas; A sampling pump, connected to the mixing chamber, is used to provide a stable negative pressure using a diaphragm vacuum pump, ensuring that the sampling probe outputs a set quantitative amount of flue gas stably, and providing stable flue gas extraction power. The central controller is used to control the coordinated operation of various components in the high-precision CO2 measurement and analysis system based on control commands. The human-machine interface module is connected to the central controller and the analyzer, and is used to receive control commands from the user to the various components in the high-precision CO2 measurement and analysis system, and to display the final detection results of the analyzer.

[0007] This invention provides a high-precision CO2 measurement and analysis method based on the dilution method for thermal power plants, used in the aforementioned high-precision CO2 measurement and analysis system based on the dilution method for thermal power plants. The method includes: The original flue gas is intercepted by inserting a sampling probe into the flue; wherein, the sampling probe is kept at a constant temperature and heated by a heat tracing pipe throughout the process to prevent water vapor condensation and acid corrosion of the sampling probe; The flue gas is heated during the flue gas transmission process by a constant temperature device; residual aerosols and dust in the cooled original flue gas are removed by the filter element of a fine filter; and diluted gas is stored and output through a dilution gas source cylinder. The flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber are precisely controlled by a sample gas mass flow controller based on the thermal principle. The filtered raw flue gas and dilution gas are turbulently mixed through the cylindrical cavity and spiral guide vanes of the mixing chamber to obtain diluted flue gas. The CO2 concentration in the diluted flue gas is detected by an analyzer. A diaphragm vacuum pump is used to provide a stable negative pressure to ensure that the sampling probe outputs the set quantitative flue gas and provides stable flue gas extraction power. The central controller controls the coordinated operation of each component in the high-precision CO2 measurement and analysis system based on control commands; the human-machine interface module receives control commands from the user for each component in the high-precision CO2 measurement and analysis system and displays the final detection results of the analyzer.

[0008] The integrated and intelligent high-precision CO2 measurement and analysis system based on the dilution method implemented in this invention can overcome the bottlenecks of existing technologies under the complex and harsh flue gas conditions of thermal power plants, and achieve continuous online monitoring of high-concentration CO2 with absolute high precision, high stability and high reliability. It also significantly improves the ease of use and maintainability of the system, providing reliable technical support for accurate carbon emission measurement and management. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of a high-precision CO2 measurement and analysis system for thermal power plants based on the dilution method, according to an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating fault diagnosis according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the mixing chamber according to an embodiment of the present invention; Figure 4 This is a flowchart of a high-precision CO2 measurement and analysis method for thermal power plants based on the dilution method, according to an embodiment of the present invention. Detailed Implementation

[0011] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0012] System Implementation Examples According to embodiments of the present invention, a high-precision CO2 measurement and analysis system based on the dilution method for thermal power plants is provided. Figure 1 This is a schematic diagram of a high-precision CO2 measurement and analysis system for thermal power plants based on the dilution method, according to an embodiment of the present invention. Figure 1 As shown in the figure, the high-precision CO2 measurement and analysis system based on the dilution method in a thermal power plant according to an embodiment of the present invention specifically includes: a sampling probe 1; a heated conduit 2; a constant temperature device 3; a fine filter 4; a mixing chamber 5; a sample gas mass flow controller 6; a human-machine interface 7; an analyzer 8; a dilution gas source cylinder 9; a sampling pump 10; and a central controller 11. The following provides a detailed description of each of the above components.

[0013] Sampling probe 1 is used to be inserted into the flue to intercept the raw flue gas; The heat tracing conduit 2 is sleeved around the sampling probe 1 and is used to provide constant temperature heat tracing for the sampling probe throughout the entire process to prevent water vapor condensation and acid corrosion of the sampling probe. The constant temperature device 3 is connected to the rear end of the sampling probe and is used to heat the flue gas during the flue gas transmission process; the default temperature is 135 degrees Celsius. The flue gas contains gaseous water, which prevents the formation of liquid water in the flue gas and thus avoids condensation.

[0014] Fine filter 4, connected to constant temperature device 3, is used to remove residual aerosols and dust from the original flue gas after cooling through the filter element; The sample gas mass flow controller 6, connected to the fine filter 4, the dilution gas source cylinder 9, and the mixing chamber 5, is used to precisely control the flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber using a thermal principle; specifically, the sample gas mass flow controller 6 is used for: A dual closed-loop control system is used for closed-loop control of the raw flue gas flow and the dilution gas flow. In the raw flue gas flow closed-loop control, the standard flow rate of the raw flue gas set by the central controller is obtained as a constant value. The valve opening of the sample gas mass flow controller is dynamically adjusted using a real-time proportional-integral-derivative algorithm; in the closed-loop control of the dilution gas flow, the target flow rate of the dilution gas set by the central controller is obtained. And based on real-time collected gas pressure With temperature The data is dynamically compensated according to Formula 1 to eliminate volumetric flow rate errors caused by gas source pressure attenuation and ambient temperature drift. Formula 1; in, , , Indicates the set flow rate; This represents the actual traffic volume.

[0015] The dilution gas source cylinder 9 is connected to the sample gas mass flow controller and is used to store and output dilution gas; Mixing chamber 5, connected to the sample gas mass flow controller, is used to perform turbulent mixing of the filtered raw flue gas and the dilution gas through a cylindrical cavity and spiral guide vanes to obtain diluted flue gas; the mixing chamber specifically includes: The sealing ring, connected to the cylindrical cavity and the spiral guide vane, is used to seal the mixing chamber and prevent air from entering. The air inlet is connected to the sample gas mass flow controller and the cylindrical cavity, and is used to send dilution gas and flue gas into the cylindrical cavity; The spiral guide vane, built into the cylindrical cavity, is used to fully mix the dilution gas and flue gas by rotating and turning, ensuring uniform mixing. A cylindrical cavity is used to mix dilution gas with flue gas within the cavity; The outlet is connected to the cylindrical cavity and is used to discharge the uniformly mixed sample gas into the analyzer for CO2 measurement and analysis.

[0016] Analyzer 8, connected to the mixing chamber 5, is used to detect the CO2 concentration in the diluted flue gas; Sampling pump 10 is connected to the mixing chamber 5 and is used to provide a stable negative pressure with a diaphragm vacuum pump to ensure that the sampling probe outputs a set quantitative amount of flue gas and provides stable flue gas extraction power. The central controller 11 is used to control the coordinated operation of various components in the high-precision CO2 measurement and analysis system based on control commands; specifically, the central controller 11 is used for: Zero-point calibration is performed on the CO2 high-precision measurement and analysis system by switching to the pipeline through which dilution gas flows through the original flue gas and dilution gas, and correcting the zero-point offset of the sample gas mass flow controller. The high-precision CO2 measurement and analysis system is calibrated across a range by controlling the flow of CO2 / N2 standard gas of known concentration into the mixing chamber. The gain coefficient of the flow controller is then calibrated in reverse using the analyzer feedback value to ensure the traceability of the dilution ratio benchmark.

[0017] A fault diagnosis architecture based on decision trees is adopted, and the fault source of the system is traced through multi-parameter correlation analysis. When an abnormal flow is detected, the diagnostic engine judges the fluctuation characteristics of the sample gas mass flow controller of the original flue gas: if the fluctuation is significant, it prompts to check the sampling probe blockage or the heat tracing pipe leakage; if the sample gas mass flow controller is running stably, it automatically verifies the dilution gas pressure sensor data. When the pressure value is lower than a certain gas pressure for a certain period of time, it triggers the "insufficient gas supply" alarm and controls the human-machine interface to display the suggested handling plan.

[0018] The human-machine interface module 7, connected to the central controller 11 and the analyzer 8, is used to receive control commands from the user to various components in the high-precision CO2 measurement and analysis system, and to display the final detection results of the analyzer. Specifically, the human-machine interface module 7 is used for: The system integrates a real-time monitoring interface, an intelligent reporting system, and a carbon emission metering module through a human-machine interface. The real-time monitoring interface dynamically displays the CO2 concentration time-series curve, dual-channel flow stability indicators, and key component status indicators. The intelligent reporting system automatically generates daily calibration logs containing calibration time, standard gas concentration, and error values, as well as monthly statistical measurement accuracy reports. The carbon emission metering module supports the periodic output of carbon emission reports that comply with MRV specifications.

[0019] This invention employs high-precision dilution ratio control technology. Through a dual-closed-loop mass flow control system, the flow rates of the sample gas and dilution gas are precisely adjusted separately to ensure a stable 100:1 (or other set ratio) dilution ratio. Based on a real-time PID algorithm, the flow rate is dynamically adjusted, combined with a temperature and pressure compensation model to eliminate the influence of environmental factors on flow control. High-efficiency mixing and low-concentration NDIR detection technology are employed. A spiral-guided turbulent mixing chamber design ensures a mixing uniformity of >98% between the sample gas and dilution gas, avoiding interference from concentration fluctuations to the NDIR analyzer. A low-range (0-2000 ppm) NDIR analyzer is selected to detect the diluted gas, avoiding nonlinear errors in direct measurement of high-concentration CO2 and improving measurement accuracy. An intelligent control and fault diagnosis system is implemented. Based on an industrial-grade PLC + ARM processor central controller, it achieves system-wide parameter optimization, adaptive adjustment, and real-time monitoring. A decision tree fault diagnosis algorithm is used to automatically identify common faults (such as probe blockage, insufficient gas supply, abnormal flow, etc.) and provide solutions through a human-machine interface, reducing maintenance difficulty. It integrates a carbon emission measurement module and automatically generates reports that comply with MRV (Monitoring, Reporting, Verification) standards, meeting the regulatory requirements of the carbon trading market.

[0020] This invention addresses the key shortcomings of existing online high-concentration CO2 measurement technologies for flue gas from thermal power plants, particularly systems based on dilution methods. The technical solution of this invention has the following advantages: (1) Improve the absolute accuracy and long-term stability of high-concentration CO2 measurement: overcome the problem of insufficient measurement accuracy and long-term drift caused by the inherent nonlinear effect and saturation effect of the analyzer when measuring high-concentration CO2 in thermal power plants by the traditional direct non-dispersive infrared (NDIR) method, so as to meet the high standard requirements for accurate carbon emission measurement.

[0021] (2) Ensure high precision, high stability and rapid response of dilution ratio: solve the core problem that the flow rates of sample gas and dilution gas are difficult to be accurately and stably controlled by the sample gas mass flow controller and dilution gas source under the complex and ever-changing working conditions of flue gas in thermal power plants, which leads to the drift and inaccuracy of dilution ratio.

[0022] (3) Enhance system integration, intelligence, and maintainability: Solve the problem of independent operation of various components and lack of unified coordination in the existing system, and realize intelligent global parameter optimization, process coordination, and adaptive adjustment of the entire system through a central controller. Through a fully functional human-machine interface, solve the problems of cumbersome parameter settings, unintuitive status monitoring, difficulty in querying historical data, and scattered alarm management in the existing system, and significantly improve the work efficiency of operators and the manageability of the system.

[0023] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] 1. Sampling probe: made of high-temperature resistant alloy material, with built-in self-cleaning ceramic filter element, directly inserted into the flue to intercept the original flue gas.

[0025] 2. Heat tracing pipe: Constant temperature heat tracing throughout the entire process to prevent water vapor condensation and acid corrosion.

[0026] 3. A constant temperature device is used to heat the flue gas during the flue gas transmission process.

[0027] 4. Fine filter: 0.1μm precision filter element, capturing residual aerosols and fine dust.

[0028] 5. Mixing Chamber: A cylindrical cavity with spiral guide vanes is used to achieve turbulent mixing (mixing uniformity >98%). Specifically, gas mixing falls under the category of fluid dynamics, which includes both gases and liquids. The spiral structure, through its unique geometric design (such as spiral blades, spiral channels, or spiral elements), promotes turbulence and mixing of fluids or materials. In existing technologies, conventional dilution sampling directly mixes flue gas and dilution gas, which cannot guarantee complete mixing uniformity. Mixing uniformity directly affects the accuracy of CO2 volume concentration measurement. Uneven mixing can lead to local concentration deviations, affecting the synchronous calculation of flow rate and humidity parameters, ultimately causing the carbon emission calculation results to deviate from the true value. Non-uniform mixing can cause measurement signal fluctuations, increasing data uncertainty. Therefore, ensuring thorough mixing of flue gas before sampling is crucial for ensuring the accuracy of daily, monthly, and annual emission calculations. Therefore, the technical solution of this invention combines the characteristics of spiral mixing with device improvements, designing the mixing device as a spiral structure. The structure of the mixing chamber is as follows... Figure 3 As shown, it specifically includes: Sealing ring 51; seals the mixing chamber to prevent air from entering; connects to the spiral guide vane of the cylindrical cavity.

[0029] Air inlet 52; sends dilution gas and flue gas into the mixing chamber; connected to the sample gas mass flow controller and cylindrical cavity.

[0030] Spiral guide vane 53: By rotating and turning, the dilution gas and flue gas are fully mixed to ensure uniform mixing. It is built into a cylindrical cavity.

[0031] Cylindrical cavity 54; dilution gas is mixed with flue gas within the cavity.

[0032] Outlet 55; the well-mixed sample gas is discharged from the outlet and enters the analyzer for CO2 measurement and analysis.

[0033] The core design of the mixing chamber is a cylindrical cavity with embedded helical guide vanes. As the shaft rotates, the helical guide vanes force the airflow along a helical path, constantly changing its direction and generating strong shear forces and eddies, thus inducing highly turbulent mixing. This high degree of turbulent mixing ensures that the sample gas and dilution gas are thoroughly and uniformly mixed in a very short time and space. Without this forced mixing, the gas may exhibit stratification (i.e., high concentration in some areas and low concentration in others).

[0034] The core objective of the mixing chamber is to eliminate uncertainty and provide a stable and uniform measurement environment. If uneven mixing causes abrupt changes in the concentration signal, the PID algorithm may misinterpret this as a sudden change in flow rate, leading to unnecessary "over-adjustment" and system oscillations, preventing the system from stabilizing at the target dilution ratio. The spiral guide vane design accelerates the mixing process, reducing the time delay and uncertainty between MFC flow adjustment and sensor detection of concentration changes. Faster response allows for more aggressive and precise parameter tuning of the PID algorithm, thereby improving the system's dynamic response speed. Furthermore, the mixing chamber reduces the impact of environmental interference and internal noise on measurement results, making fault diagnosis more accurate. The high-intensity mixing significantly reduces "measurement noise" caused by uneven mixing, allowing the diagnostic engine to more confidently attribute flow anomalies to genuine physical faults rather than falsely reporting fluctuations caused by uneven mixing.

[0035] 6. Sample gas mass flow controller (MFC): thermal principle, range 0-50 mL / min, accuracy ±0.5% RD.

[0036] 7. Human-machine interface: 10-inch touch screen, supporting Modbus communication.

[0037] 8. Analyzer: Low-range NDIR (range 0-2000 ppm), specifically designed for the detection of low concentrations of CO2 after dilution.

[0038] 9. Diluent gas source cylinder: 99.999% high-purity nitrogen, equipped with a pressure reducing valve (output pressure 0.2 MPa).

[0039] 10. Sampling pump: Diaphragm vacuum pump. The diaphragm vacuum pump provides a stable negative pressure to ensure that the sampling probe outputs the set quantitative flue gas and provides stable flue gas extraction power. 11. Central controller: Industrial-grade PLC + ARM processor, with integrated AD / DA conversion module.

[0040] Workflow: Flue gas → Sampling probe (coarse filtration) → Heated conduit (constant temperature transmission) → Temperature control device (stabilizes dew point temperature) → Fine filter (fine dust removal) → Sample gas MFC (precise flow control) → Mixing chamber (mixes with dilution gas at a 1:99 ratio) → Sampling pump (provides stable pumping power) → Analyzer (detects diluted CO2). All of the above processes are controlled by a central controller.

[0041] (2) High-precision control method for dilution ratio.

[0042] This invention constructs a dual closed-loop control system based on a mass flow controller, including a sample gas flow control loop and a dilution gas flow control loop. In the sample gas flow control loop, the central controller sets the standard flow rate of the sample gas to a constant value. The MFC valve opening is dynamically adjusted using a real-time PID (proportional-integral-derivative) algorithm, with a response time ≤ 100 ms, ensuring flow fluctuation < ±0.5%. In the dilution gas flow control loop, the target flow rate of the dilution gas is locked at [value missing]. (Achieving a fixed dilution ratio of 100x), based on real-time gas pressure data. With temperature The data is dynamically compensated according to the following formula:

[0043] in , The standard reference conditions are used. This compensation model eliminates volumetric flow rate errors caused by gas source pressure decay and ambient temperature drift.

[0044] To suppress long-term drift of the flow sensor, the system performs the following calibration procedure every 24 hours: Zero-point calibration: Switch to high-purity nitrogen (≥99.999%) flowing through the sample gas and dilution gas lines to correct the MFC zero-point offset. Span calibration: Introduce a known concentration into the mixing chamber. The CO2 / N2 standard gas is used to back-calibrate the flow controller's gain coefficient through the analyzer's feedback value, ensuring the traceability of the dilution ratio benchmark. Specifically, traceability ensures that the measurement results are accurate, reliable, and verifiable. Instruments themselves will drift and produce errors over time and with environmental changes. One cannot assume, "If I set the flow rate to 10 mL / min, it will be exactly 10 mL / min." The "traceability" step aims to correct for this potential error.

[0045] It should be noted that the system supports setting a fixed time each day (such as early morning when production load is low) to automatically start the calibration procedure. During calibration, the system will automatically mark the measurement data as 'calibration maintenance status' and will not participate in real-time emission calculations, complying with the standards and specifications of continuous emission monitoring systems, thereby ensuring the validity of business data and the long-term accuracy of measuring instruments.

[0046] (3) Intelligent control and operation and maintenance management system like Figure 2 As shown, the system adopts a fault diagnosis architecture based on decision trees, and realizes fault tracing through multi-parameter correlation analysis. When an abnormal flow is detected, the diagnostic engine first judges the fluctuation characteristics of the sample gas MFC: if the fluctuation is significant, it prompts to check the sampling probe blockage or the heating pipe leakage; if the MFC is running stably, it automatically verifies the dilution gas pressure sensor data. When the pressure value is below 0.15 MPa for 30 seconds, it triggers a level 3 "insufficient gas supply" alarm and displays the suggested handling solution through the human-machine interface.

[0047] It should be noted that a complete system will also monitor a variety of other faults, such as: the temperature of the heat tracing pipe is too low or too high, the pump's pumping force is insufficient or it stops, and the sample gas leaks before entering the MFC. The handling method is similar to the decision tree above. When an anomaly is detected, its characteristics, corresponding causes, and response measures are analyzed layer by layer. Flow anomaly is the most typical anomaly.

[0048] Furthermore, the aforementioned "fluctuation characteristics" refer to the specific patterns of flow data changes. Specifically, this can be interpreted as follows: High-frequency, irregular, and drastic fluctuations: This usually indicates the presence of condensate in the pipeline or severe turbulence in the flue gas at the sampling probe. Slow, trending declines: This likely indicates that the sampling probe or filter is gradually becoming clogged. Periodic, stable fluctuations: This may be related to upstream pressure fluctuations or improper PID parameter tuning of the PLC. A sudden drop in value to zero or near zero: This indicates that the pipeline is completely blocked or the sampling pump has stopped.

[0049] The human-machine interface integrates a "real-time monitoring interface," an "intelligent reporting system," and a "carbon emission measurement module." The real-time monitoring interface dynamically displays the CO2 concentration time-series curve (1Hz refresh rate), dual-channel flow stability indicators, and status indicator lights for key components. The intelligent reporting system automatically generates daily calibration logs containing calibration time, standard gas concentration, and error values, as well as monthly PDF reports summarizing measurement accuracy. The carbon emission measurement module supports hourly / daily / monthly output of carbon emission reports compliant with MRV standards.

[0050] As can be seen from the above description, the technical solution of this invention consists of a mass flow controller, a specially designed mixing chamber, and a central controller, forming a technical architecture for achieving high-precision and stable dilution and intelligent operation and maintenance. The sample gas mass flow controller is the foundation for achieving accurate and stable dilution ratios; the mixing chamber, especially the "cylindrical cavity + spiral guide vane design," is a key physical structure that ensures uniform gas concentration and stable analyzer readings after dilution; the central controller is the brain of the entire system, responsible for running core software such as PID algorithms, temperature and pressure compensation models, and fault diagnosis decision trees, intelligently coordinating all hardware components.

[0051] In summary, the technical solutions described above using the embodiments of the present invention have the following beneficial effects: (1) Significantly improves the accuracy and long-term stability of high-concentration CO2 measurement: Through an innovative dilution method design, high-concentration CO2 flue gas is diluted to a low concentration range at a precise ratio, effectively avoiding the inherent nonlinear error and saturation effect of traditional NDIR analyzers in the high-concentration range. Combined with dual closed-loop flow control and dynamic temperature and pressure compensation algorithm, the high accuracy of the dilution ratio and anti-interference ability are ensured.

[0052] (2) Achieving highly reliable control and adaptive optimization of the dilution ratio: A dual-path mass flow controller for sample gas and dilution gas is used for coordinated control, combined with a real-time PID algorithm and a temperature and pressure compensation model to dynamically correct flow deviations. The system automatically performs zero-point and span calibrations daily, and eliminates sensor drift through traceable calibration to ensure long-term stability of the dilution ratio. The turbulence design of the mixing chamber further reduces concentration fluctuations and ensures the stability of the analyzer's input signal.

[0053] (3) Enhance system intelligence and operation and maintenance efficiency: The central controller based on industrial-grade PLC+ARM processor realizes global collaborative control and integrates adaptive parameter adjustment and data management functions. The human-machine interface provides real-time curve monitoring, automatic generation of calibration logs and carbon emission reports in accordance with MRV specifications, reducing manual intervention.

[0054] Method Implementation Examples According to embodiments of the present invention, a high-precision CO2 measurement and analysis method based on the dilution method for thermal power plants is provided, which is used in the aforementioned high-precision CO2 measurement and analysis system based on the dilution method for thermal power plants. Figure 4 This is a flowchart of a high-precision CO2 measurement and analysis method for thermal power plants based on the dilution method, according to an embodiment of the present invention. Figure 4 As shown, the high-precision CO2 measurement and analysis method based on the dilution method in thermal power plants according to an embodiment of the present invention specifically includes: Step S301: The original flue gas is intercepted by inserting a sampling probe into the flue; wherein, the sampling probe is kept at a constant temperature and heated by a heat tracing pipe throughout the process to prevent water vapor condensation and acid corrosion of the sampling probe; Step S302: The flue gas is heated during the flue gas transmission process using a constant temperature device; residual aerosols and dust in the cooled original flue gas are removed through the filter element of a fine filter; and diluted gas is stored and output through a dilution gas source cylinder. Step S303: The flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber are precisely controlled by a sample gas mass flow controller using a thermal principle; the filtered raw flue gas and dilution gas are turbulently mixed through the cylindrical cavity and spiral guide vanes of the mixing chamber to obtain diluted flue gas; the CO2 concentration in the diluted flue gas is detected by an analyzer; a diaphragm vacuum pump is used to provide a stable negative pressure to ensure that the sampling probe stably outputs the set quantitative flue gas and provides stable flue gas extraction power; Specifically, the precise control of the flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber using a sample gas mass flow controller based on a thermal principle includes: employing a dual closed-loop control system for closed-loop control of the raw flue gas flow and closed-loop control of the dilution gas flow. In the closed-loop control of the raw flue gas flow, the standard flow rate of the raw flue gas set by the central controller is obtained as a constant value. The valve opening of the sample gas mass flow controller is dynamically adjusted using a real-time proportional-integral-derivative algorithm; in the closed-loop control of the dilution gas flow, the target flow rate of the dilution gas set by the central controller is obtained. And based on real-time collected gas pressure With temperature The data is dynamically compensated according to Formula 1 to eliminate volumetric flow rate errors caused by gas source pressure attenuation and ambient temperature drift. Formula 1; in, , , Indicates the set flow rate; This represents the actual traffic volume.

[0055] The filtered raw flue gas and dilution gas are turbulently mixed through the cylindrical cavity and spiral guide vanes of the mixing chamber to obtain the diluted flue gas, which specifically includes: A sealing ring is used to seal the mixing chamber and prevent air from entering. Diluent and flue gas are introduced into the cylindrical cavity through the air inlet; The dilution gas and flue gas are thoroughly mixed by the rotation of the spiral guide vanes to ensure uniform mixing. The dilution gas is mixed with the flue gas through a cylindrical cavity; The uniformly mixed sample gas is discharged through the outlet and enters the analyzer for CO2 measurement and analysis.

[0056] Step S304: The central controller controls the coordinated operation of each component in the high-precision CO2 measurement and analysis system based on control commands; the human-machine interface module receives the user's control commands for each component in the high-precision CO2 measurement and analysis system and displays the final detection results of the analyzer.

[0057] Specifically, the control of the coordinated operation of various components in the high-precision CO2 measurement and analysis system by the central controller based on control commands includes: Zero-point calibration is performed on the CO2 high-precision measurement and analysis system by switching to the pipeline through which dilution gas flows through the original flue gas and dilution gas, and correcting the zero-point offset of the sample gas mass flow controller. The CO2 high-precision measurement and analysis system is calibrated across a span, controlling the flow of CO2 / N2 standard gas of known concentration into the mixing chamber. The gain coefficient of the flow controller is calibrated in reverse using the analyzer feedback value to ensure the traceability of the dilution ratio benchmark. A fault diagnosis architecture based on a decision tree is adopted, and the system fault is traced through multi-parameter correlation analysis. When an abnormal flow is detected, the diagnostic engine judges the fluctuation characteristics of the sample gas mass flow controller of the original flue gas: if the fluctuation is significant, it prompts to check the sampling probe blockage or the heating pipe leakage; if the sample gas mass flow controller is running stably, it automatically verifies the dilution gas pressure sensor data. When the pressure value is lower than a certain pressure for a certain period of time, it triggers the "insufficient gas supply" alarm and controls the human-machine interface to display the suggested handling plan.

[0058] The human-machine interface module receives control commands from the user for each component of the high-precision CO2 measurement and analysis system, and displays the final detection results of the analyzer, including: The system integrates a real-time monitoring interface, an intelligent reporting system, and a carbon emission metering module through a human-machine interface. The real-time monitoring interface dynamically displays the CO2 concentration time-series curve, dual-channel flow stability indicators, and key component status indicators. The intelligent reporting system automatically generates daily calibration logs containing calibration time, standard gas concentration, and error values, as well as monthly statistical measurement accuracy reports. The carbon emission metering module supports the periodic output of carbon emission reports that comply with MRV specifications.

[0059] The embodiments of the present invention are method embodiments corresponding to the above system embodiments. The specific operations of each process can be understood with reference to the description of the system embodiments, and will not be repeated here.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision CO2 measurement and analysis system for thermal power plants based on the dilution method, characterized in that, include: A sampling probe is used to insert into the flue to capture raw flue gas; A heat tracing conduit, fitted around the sampling probe and located inside the flue, is used to provide constant temperature heat tracing for the sampling probe throughout its entire process, preventing water vapor condensation and acid corrosion of the sampling probe. A constant temperature device, connected to the rear end of the sampling probe, is located outside the flue and is used to heat the flue gas during the flue gas transmission process; A fine filter, connected to a thermostat, is used to remove residual aerosols and dust from the cooled raw flue gas through the filter element; A sample gas mass flow controller, connected to the fine filter, dilution gas source cylinder, and mixing chamber, is used to precisely control the flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber using a thermal principle. A dilution gas source cylinder is connected to the sample gas mass flow controller for storing and outputting dilution gas; The mixing chamber, connected to the sample gas mass flow controller, is used to perform turbulent mixing of the filtered raw flue gas and the dilution gas through a cylindrical cavity and a spiral guide vane to obtain diluted flue gas. A sampling pump, connected to the mixing chamber, is used to provide a stable negative pressure using a diaphragm vacuum pump, ensuring that the sampling probe outputs a set quantitative amount of flue gas stably, and providing stable flue gas extraction power. An analyzer, connected to the mixing chamber, is used to detect the CO2 concentration in the diluted flue gas; The central controller is used to control the coordinated operation of various components in the high-precision CO2 measurement and analysis system based on control commands. The human-machine interface module is connected to the central controller and the analyzer, and is used to receive control commands from the user to the various components in the high-precision CO2 measurement and analysis system, and to display the final detection results of the analyzer.

2. The system according to claim 1, characterized in that, The sample gas mass flow controller is specifically used for: A dual closed-loop control system is used for closed-loop control of the raw flue gas flow and the dilution gas flow. In the raw flue gas flow closed-loop control, the standard flow rate of the raw flue gas set by the central controller is obtained as a constant value. The valve opening of the sample gas mass flow controller is dynamically adjusted using a real-time proportional-integral-derivative algorithm; in the closed-loop control of the dilution gas flow, the target flow rate of the dilution gas set by the central controller is obtained. And based on real-time collected gas pressure With temperature The data is dynamically compensated according to Formula 1 to eliminate volumetric flow rate errors caused by gas source pressure attenuation and ambient temperature drift. Official 1; in, , , Indicates the set flow rate; This represents the actual traffic volume.

3. The system according to claim 1, characterized in that, The central controller is specifically used for: Zero-point calibration is performed on the CO2 high-precision measurement and analysis system by switching to the pipeline through which dilution gas flows through the original flue gas and dilution gas, and correcting the zero-point offset of the sample gas mass flow controller. The high-precision CO2 measurement and analysis system is calibrated across a range by controlling the flow of CO2 / N2 standard gas of known concentration into the mixing chamber and using the analyzer feedback value to calibrate the gain coefficient of the flow controller in reverse, thus ensuring the traceability of the dilution ratio benchmark. A fault diagnosis architecture based on decision trees is adopted, and the fault source of the system is traced through multi-parameter correlation analysis. When an abnormal flow is detected, the diagnostic engine judges the fluctuation characteristics of the sample gas mass flow controller of the original flue gas: if the fluctuation is significant, it prompts to check the sampling probe blockage or the heat tracing pipe leakage; if the sample gas mass flow controller is running stably, it automatically verifies the dilution gas pressure sensor data. When the pressure value is lower than a certain gas pressure for a certain period of time, it triggers the "insufficient gas supply" alarm and controls the human-machine interface to display the suggested handling plan.

4. The system according to claim 1, characterized in that, The mixing chamber specifically includes: The sealing ring, connected to the cylindrical cavity and the spiral guide vane, is used to seal the mixing chamber and prevent air from entering. The air inlet is connected to the sample gas mass flow controller and the cylindrical cavity, and is used to send dilution gas and flue gas into the cylindrical cavity; The spiral guide vane, built into the cylindrical cavity, is used to fully mix the dilution gas and flue gas by rotating and turning, ensuring uniform mixing. A cylindrical cavity is used to mix dilution gas with flue gas within the cavity; The outlet is connected to the cylindrical cavity and is used to discharge the uniformly mixed sample gas into the analyzer for CO2 measurement and analysis.

5. The system according to claim 1, characterized in that, The human-machine interface module is specifically used for: The system integrates a real-time monitoring interface, an intelligent reporting system, and a carbon emission metering module through a human-machine interface. The real-time monitoring interface dynamically displays the CO2 concentration time-series curve, dual-channel flow stability indicators, and key component status indicators. The intelligent reporting system automatically generates daily calibration logs containing calibration time, standard gas concentration, and error values, as well as monthly statistical measurement accuracy reports. The carbon emission metering module supports the periodic output of carbon emission reports that comply with MRV specifications.

6. A high-precision measurement and analysis method for CO2 in thermal power plants based on the dilution method, characterized in that, The high-precision CO2 measurement and analysis system for thermal power plants based on the dilution method, as described in any one of claims 1 to 5, specifically includes the following method: The original flue gas is intercepted by inserting a sampling probe into the flue; wherein, the sampling probe is kept at a constant temperature and heated by a heat tracing pipe throughout the process to prevent water vapor condensation and acid corrosion of the sampling probe; The flue gas is heated during the transmission process by a constant temperature device; residual aerosols and dust in the cooled original flue gas are removed by the filter element of a fine filter; and diluted gas is stored and output through a dilution gas source cylinder. The flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber are precisely controlled by a sample gas mass flow controller based on the thermal principle. The filtered raw flue gas and dilution gas are turbulently mixed through the cylindrical cavity and spiral guide vanes of the mixing chamber to obtain diluted flue gas. The CO2 concentration in the diluted flue gas is detected by an analyzer. A diaphragm vacuum pump is used to provide a stable negative pressure to ensure that the sampling probe outputs the set quantitative flue gas and provides stable flue gas extraction power. The central controller controls the coordinated operation of each component in the high-precision CO2 measurement and analysis system based on control commands; the human-machine interface module receives control commands from the user for each component in the high-precision CO2 measurement and analysis system and displays the final detection results of the analyzer.

7. The method according to claim 6, characterized in that, The sample gas mass flow controller uses a thermal principle to precisely control the flow rates of the filtered raw flue gas and dilution gas entering the mixing chamber. Specifically, this involves employing a dual closed-loop control system for both the raw flue gas and dilution gas flow closed-loop control. In the raw flue gas flow closed-loop control, the standard flow rate of the raw flue gas set by the central controller is kept constant. The valve opening of the sample gas mass flow controller is dynamically adjusted using a real-time proportional-integral-derivative algorithm; in the closed-loop control of the dilution gas flow, the target flow rate of the dilution gas set by the central controller is obtained. And based on real-time collected gas pressure With temperature The data is dynamically compensated according to Formula 1 to eliminate volumetric flow rate errors caused by gas source pressure attenuation and ambient temperature drift. Official 1; in, , , Indicates the set flow rate; This represents the actual traffic volume.

8. The method according to claim 6, characterized in that, The control of the coordinated operation of various components in the high-precision CO2 measurement and analysis system via a central controller based on control commands specifically includes: Zero-point calibration is performed on the CO2 high-precision measurement and analysis system by switching to the pipeline through which dilution gas flows through the original flue gas and dilution gas, and correcting the zero-point offset of the sample gas mass flow controller. The high-precision CO2 measurement and analysis system is calibrated across a range by controlling the flow of CO2 / N2 standard gas of known concentration into the mixing chamber and using the analyzer feedback value to calibrate the gain coefficient of the flow controller in reverse, thus ensuring the traceability of the dilution ratio benchmark. A fault diagnosis architecture based on decision trees is adopted, and the fault source of the system is traced through multi-parameter correlation analysis. When an abnormal flow is detected, the diagnostic engine judges the fluctuation characteristics of the sample gas mass flow controller of the original flue gas: if the fluctuation is significant, it prompts to check the sampling probe blockage or the heat tracing pipe leakage; if the sample gas mass flow controller is running stably, it automatically verifies the dilution gas pressure sensor data. When the pressure value is lower than a certain gas pressure for a certain period of time, it triggers the "insufficient gas supply" alarm and controls the human-machine interface to display the suggested handling plan.

9. The method according to claim 6, characterized in that, The filtered raw flue gas and dilution gas are turbulently mixed through the cylindrical cavity and spiral guide vanes of the mixing chamber to obtain the diluted flue gas, which specifically includes: A sealing ring is used to seal the mixing chamber and prevent air from entering. Diluent and flue gas are introduced into the cylindrical cavity through the air inlet; The dilution gas and flue gas are thoroughly mixed by the rotation of the spiral guide vanes to ensure uniform mixing. The dilution gas is mixed with the flue gas through a cylindrical cavity; The uniformly mixed sample gas is discharged through the outlet and enters the analyzer for CO2 measurement and analysis.

10. The method according to claim 6, characterized in that, The human-machine interface module receives control commands from the user for each component of the high-precision CO2 measurement and analysis system, and displays the final detection results of the analyzer, including: The system integrates a real-time monitoring interface, an intelligent reporting system, and a carbon emission metering module through a human-machine interface. The real-time monitoring interface dynamically displays the CO2 concentration time-series curve, dual-channel flow stability indicators, and key component status indicators. The intelligent reporting system automatically generates daily calibration logs containing calibration time, standard gas concentration, and error values, as well as monthly statistical measurement accuracy reports. The carbon emission metering module supports the periodic output of carbon emission reports that comply with MRV specifications.

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