A flue gas carbon dioxide on-line monitoring method and monitoring device

Abstract

The application discloses a flue gas carbon dioxide online monitoring method and a monitoring device, and belongs to the technical field of gas monitoring. The method comprises the following steps: collecting flue gas discharged by an emission source and performing impurity removal treatment; detecting the carbon dioxide concentration in the pretreated flue gas, and synchronously collecting the temperature, humidity and pressure of the pretreated flue gas; performing real-time compensation correction on the carbon dioxide concentration according to the temperature, humidity and pressure; performing threshold checking and trend checking on the compensated and corrected carbon dioxide concentration data to identify and eliminate abnormal jump data; and outputting the carbon dioxide monitoring data after compensation correction and data checking. Through synchronous collection of multiple parameters and compensation correction, the application eliminates the influence of environmental parameter fluctuation on detection accuracy; through a threshold and trend double-checking mechanism, abnormal jump data is effectively eliminated, the accuracy and reliability of monitoring data are improved, and the application is suitable for real-time online monitoring of carbon dioxide concentration of industrial boilers, kilns and other emission sources.

Description

Technical Field

[0001] This application relates to the field of gas monitoring technology, and in particular to a method and device for online monitoring of carbon dioxide in flue gas. Background Technology

[0002] As a major source of carbon dioxide emissions, the industrial sector's monitoring of carbon dioxide emissions from sources such as coal-fired boilers, gas turbines, cement kilns, and metallurgical kilns is a core foundation for carbon emission accounting, carbon reduction effectiveness assessment, and data support for the carbon trading market. Accurate, real-time, and continuous acquisition of carbon dioxide concentration data in flue gas from emission sources is of significant practical importance for enterprises to optimize production processes, reduce carbon emission intensity, and for regulatory authorities to implement regional total carbon emission control.

[0003] Currently, the main technical bottlenecks in the practical application of online carbon dioxide monitoring devices for industrial emission sources are as follows: First, the sampling pipeline lacks effective anti-blocking and heat tracing measures. During the transmission of high-temperature and high-humidity flue gas, water vapor condenses and condenses, which, when mixed with dust, easily causes blockage of the probe and pipeline, leading to frequent equipment shutdowns. Second, the detection unit is equipped with only a single sensor and does not introduce a multi-parameter compensation mechanism for temperature, humidity, pressure, etc. Fluctuations in flue gas environmental parameters significantly affect the detection accuracy of infrared sensors. Actual measurements show that a temperature fluctuation of 50℃ can introduce an error of ±3% or more. Third, the data processing method is crude, lacking effective means to identify and eliminate abnormal data jumps such as sensor signal spikes and electromagnetic interference. Abnormal data is mixed with valid data during storage and transmission. In addition, the pollution monitoring database suffers from a single communication method and no retransmission mechanism for network outages, making it difficult to guarantee the integrity of data time sequence. Summary of the Invention

[0004] This application provides a method and device for online monitoring of carbon dioxide in flue gas, which solves the problems mentioned in the background art.

[0005] In a first aspect, embodiments of this application provide a method for online monitoring of carbon dioxide in flue gas, including: S1: Collect the flue gas emitted from the emission source and remove impurities from the flue gas to obtain pretreated flue gas; S2: Detect the carbon dioxide concentration in the pretreated flue gas, and simultaneously collect the temperature, humidity and pressure of the pretreated flue gas; S3: The carbon dioxide concentration is compensated and corrected in real time based on the temperature, humidity and pressure to eliminate the impact of environmental parameter fluctuations on detection accuracy; S4: Perform data validity verification on the carbon dioxide concentration data after compensation and correction in step S3. The data validity verification includes threshold verification and trend verification. The threshold verification is used to determine whether a single data point exceeds a preset threshold range, and the trend verification is used to determine whether the changing trend of multiple consecutive data points exceeds a preset rate of change range, so as to identify and remove abnormally abrupt data. S5: Output the carbon dioxide monitoring data after the compensation correction and data verification.

[0006] In conjunction with the first aspect, in one possible implementation, in step S1, the flue gas is heated and kept warm before being transferred from the sampling point to the condensation treatment stage, and then sequentially undergoes filtration and dust removal, condensation and cooling treatment, and gas-liquid separation to remove condensate.

[0007] In conjunction with the first aspect, in one possible implementation, the online monitoring method for carbon dioxide in flue gas further includes zero-point calibration and / or range calibration of the sensor detecting the carbon dioxide concentration; the zero-point calibration is performed using high-purity nitrogen, and the range calibration is performed using a standard gas.

[0008] In conjunction with the first aspect, in one possible implementation, in step S5, when communication is normal, the carbon dioxide monitoring data is sent to an external terminal via a wireless network; when communication is interrupted, the carbon dioxide monitoring data is cached locally and automatically retransmitted after communication is restored; the abnormal jump data is stored locally and not sent out.

[0009] Secondly, embodiments of this application provide an online monitoring device for flue gas carbon dioxide, employing the aforementioned online monitoring method for flue gas carbon dioxide, including: A sampling preprocessing unit is used to perform step S1. The sampling preprocessing unit includes a sampling probe, a filter assembly, a condensation assembly, and a gas-liquid separation assembly arranged sequentially along the gas path, as well as a pump for providing suction power. A heat tracing assembly is also provided in the gas path for heat tracing and keeping the flue gas warm during the process of the flue gas being transferred from the sampling probe to the condensation assembly. The detection unit is connected to the sampling preprocessing unit and is used to execute S2. The detection unit is equipped with a carbon dioxide sensor, a temperature sensor, a humidity sensor and a pressure sensor. A data processing unit, electrically connected to the detection unit, is used to execute S3 and S4. The data processing unit includes a compensation and correction module and a data verification module; and... The protective housing houses at least some components of the sampling preprocessing unit, the detection unit, and the data processing unit.

[0010] In conjunction with the second aspect, in one possible implementation, the inner wall of the protective housing is provided with a heat insulation layer to maintain the working temperature inside the protective housing within a preset temperature range.

[0011] In conjunction with the second aspect, in one possible implementation, the flue gas carbon dioxide online monitoring device further includes a cleaning unit; The cleaning unit is connected to the gas path of the sampling pretreatment unit and / or the gas path of the detection unit, and is used to introduce cleaning gas into the gas path to remove dust or impurities accumulated in the gas path.

[0012] In conjunction with the second aspect, in one possible implementation, the flue gas carbon dioxide online monitoring device further includes a calibration unit; The calibration unit is connected to the detection unit and is used to perform zero-point calibration and / or range calibration on the detection unit. The calibration unit includes a zero-point calibration module and a range calibration module. The zero-point calibration module has a built-in nitrogen generator for zero-point calibration of the detection unit. The range calibration module has a standard gas interface for connecting a standard gas to perform range calibration of the detection unit.

[0013] In conjunction with the second aspect, in one possible implementation, the data processing unit further includes a communication module and a local storage module; the communication module is used to send the carbon dioxide monitoring data to an external terminal, and the local storage module is used to cache the carbon dioxide monitoring data when communication is interrupted and automatically retransmit it after communication is restored; when the data verification module determines that the current carbon dioxide concentration data is abnormally fluctuating, the abnormally fluctuating data is stored in the local storage module and is not sent out through the communication module.

[0014] In conjunction with the second aspect, in one possible implementation, the cleaning unit includes a gas backflushing unit, which is connected to the sampling probe, the gas detection chamber of the detection unit, and the gas pipeline of the sampling pretreatment unit, respectively; the gas backflushing unit is activated according to a preset cycle or in response to an external command to clean the gas path.

[0015] One or more technical solutions provided in the embodiments of this application have at least the following technical effects: This application maintains a high temperature during flue gas transmission using a heat tracing component to prevent premature condensation of moisture. Through sequential processing including filtration, condensation, and gas-liquid separation, dust and moisture are removed at the source, resolving the issues of sampling pipeline blockage and condensation. Simultaneously, this application collects flue gas temperature, humidity, and pressure parameters while detecting carbon dioxide concentration. A compensation and correction module provides real-time compensation and correction for environmental parameter fluctuations, eliminating the impact of temperature, humidity, and pressure changes on infrared detection accuracy. This application employs a dual-layer data verification mechanism consisting of threshold and trend verification to effectively identify and eliminate abnormal data jumps. Abnormal data is stored locally and not transmitted externally, preventing abnormal data from contaminating the monitoring database. A mechanism of local caching during network outages and automatic retransmission upon network recovery ensures the integrity of the data sequence. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the online carbon dioxide monitoring device for flue gas provided in the embodiments of this application; Figure 2 A flowchart of the online monitoring method for carbon dioxide in flue gas provided in the embodiments of this application; Figure 3 Electrical connection block diagram of the detection unit, data processing unit, calibration unit and power supply unit provided in the embodiments of this application.

[0018] Icons: 1-Sampling preprocessing unit; 11-Sampling probe; 12-Heating assembly; 13-Filter assembly; 131-Primary filter; 132-Precision filter; 14-Condensation assembly; 15-Gas-liquid separation assembly; 16-Air pump; 2-Detection unit; 21-Carbon dioxide sensor; 22-Temperature sensor; 23-Humidity sensor; 24-Pressure sensor; 3-Data processing unit; 31-Compensation and correction module; 32-Data verification module; 33-Local storage module; 34-Communication module; 35-Microprocessor; 4-Protective housing; 5-Cleaning unit; 6-Calibration unit; 61-Zero point calibration module; 62-Range calibration module; 7-Power supply unit; 71-Mains power supply module; 72-Backup power supply module; 73-Power monitoring module; 74-Power failure alarm module. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0021] This application provides a method for online monitoring of carbon dioxide in flue gas, such as... Figures 2-3 As shown, the method includes steps S1 to S5: S1: Collect the flue gas emitted from the emission source and remove impurities from the flue gas to obtain pretreated flue gas.

[0022] Sampling probe 11 is inserted into the upper part of the emission source flue (an area with smooth flue gas flow and strong representativeness). Under the suction power of the suction pump 16, the high-temperature flue gas in the flue enters the sampling probe 11. The sampling probe 11 is a high-temperature resistant stainless steel probe with a built-in stainless steel sintered filter screen. The filter screen has a pore size of 5μm~10μm and can withstand a high-temperature environment of 300℃~800℃, used for preliminary interception of large particulate dust. The flue gas then enters the heat tracing component 12 (electric heat tracing and insulation pipe), and the heat tracing temperature is controlled at 120℃~150℃. At this temperature, the flue gas is transported to the filter component 13. The purpose of heat tracing and insulation is to ensure that the temperature of the flue gas is always higher than the water vapor dew point temperature during the transmission process, preventing water vapor from condensing and condensing before reaching the condensation component 14. Once condensation occurs prematurely, the condensate mixes with the dust in the flue gas to form a viscous substance, which will block the filter component 13 and the gas pipeline. In a dry state, the flue gas passes sequentially through the primary filter 131 and the precision filter 132 of the filter assembly 13 to remove dust and oil before entering the condenser assembly 14.

[0023] The condensation component 14 is a semiconductor condensation device that lowers the flue gas temperature to 20℃~30℃, causing the water vapor in the flue gas to condense into liquid water. The cooled flue gas then enters the gas-liquid separation component 15, which is a cyclone gas-liquid separator. This separator efficiently separates the condensate, achieving a dehydration efficiency of no less than 99%, resulting in dry, clean, and temperature-controlled pretreated flue gas for subsequent testing.

[0024] Heat tracing ensures that the filtration process is carried out in a high-temperature and dry state, preventing condensate from mixing with dust and clogging the filter; condensation is carried out after filtration, which ensures that the inside of the condenser is not easily contaminated by dust and extends the maintenance cycle of the condenser.

[0025] S2: Detect the carbon dioxide concentration in the pretreated flue gas and simultaneously collect the temperature, humidity and pressure of the pretreated flue gas.

[0026] The pretreated flue gas enters the gas detection chamber under the drive of the suction pump 16. The gas detection chamber is a sealed chamber with a built-in gas equalization plate. After being evenly distributed by the equalization plate, the pretreated flue gas stably passes through the detection area of ​​the carbon dioxide sensor 21.

[0027] The carbon dioxide sensor 21 is a non-dispersive infrared sensor with a measurement range of 0~50000ppm, a measurement accuracy of ±1%FS, and a response time of no more than 5s, enabling real-time detection of carbon dioxide concentration in the pretreated flue gas. Simultaneously, the temperature sensor 22, humidity sensor 23, and pressure sensor 24 synchronously collect the temperature, humidity, and pressure parameters of the flue gas within the gas detection chamber. All sensors collect data at a frequency of 1 time / second, and the detection data is transmitted in real-time to the microprocessor 35 of the data processing unit 3.

[0028] It should be noted that the synchronous acquisition time of temperature, humidity, and pressure parameters is consistent with the detection time of carbon dioxide concentration to ensure that the three sets of parameters reflect the environmental conditions of the same flue gas sample at the same time, providing an accurate data basis for subsequent compensation and correction.

[0029] S3: Real-time compensation and correction of carbon dioxide concentration based on temperature, humidity and pressure to eliminate the impact of environmental parameter fluctuations on detection accuracy.

[0030] The microprocessor 35 has a built-in temperature, humidity and pressure compensation algorithm. This algorithm is based on the ideal gas law and the temperature and pressure correction coefficients of the gas molecule absorption spectrum to perform real-time compensation and correction on the original concentration value output by the carbon dioxide sensor 21.

[0031] Specifically, the infrared carbon dioxide sensor 21 operates on the principle of characteristic absorption of infrared light by carbon dioxide molecules at specific wavelengths. However, the density of gas molecules decreases with increasing temperature and increases with increasing pressure, leading to differences in the absorption signal intensity under different temperature and pressure conditions for the same volume fraction. Furthermore, water vapor molecules also exhibit some absorption interference in the infrared band. The compensation algorithm corrects the original detection value point-by-point based on parameters collected in real-time by the temperature sensor 22, humidity sensor 23, and pressure sensor 24, converting the non-standard detection value into an equivalent concentration value under standard conditions. After compensation and correction, the measurement accuracy of carbon dioxide concentration can be controlled within ±1%FS.

[0032] S4: Perform data validity verification on the carbon dioxide concentration data after compensation and correction in step S3. Data validity verification includes threshold verification and trend verification. Threshold verification is used to determine whether a single data point exceeds the preset threshold range, and trend verification is used to determine whether the changing trend of multiple consecutive data points exceeds the preset change rate range, so as to identify and remove abnormal jump data.

[0033] Specifically, the data verification module 32 performs double-layer verification on the compensated and corrected data: Threshold verification: Determines whether single-point data exceeds a preset threshold range. The threshold range includes the upper limit of the sensor's measurement range (e.g., 50,000 ppm) and a reasonable emission concentration range set according to the emission source type (e.g., 0~40,000 ppm). If single-point data exceeds this range, it is marked as abnormal data.

[0034] Trend verification: This function determines whether the changing trend of multiple consecutive data points (e.g., 10 consecutive sets of data) exceeds a preset rate of change range (e.g., whether the rate of change exceeds ±5%). Under normal operating conditions, the carbon dioxide concentration change in the flue gas from emission sources is gradual and will not occur with large jumps in a short period of time. If the rate of change of consecutive data points is abnormal, it is marked as abnormal data. Trend verification can identify abnormal data that threshold verification cannot detect—for example, a concentration value jump caused by a momentary spike in electromagnetic interference. This jump value may still be within the measurement range, but the rate of change far exceeds the rate of change under normal operating conditions, and is therefore invalid data.

[0035] Data that is determined to be abnormally abruptly changed will not be included in subsequent carbon emission accounting. It will only be stored in the local storage module 33 for fault tracing and will not be sent out through the communication module 34.

[0036] S5: Outputs carbon dioxide monitoring data after compensation, correction, and data verification.

[0037] The valid monitoring data after compensation and correction in step S3 and data verification in step S4 is output to an external terminal through communication module 34.

[0038] The communication module 34 adopts dual-mode communication: short-distance communication with the enterprise's local monitoring terminal via LoRa, and long-distance communication with the park's carbon emission monitoring platform via 4G / 5G public network, with a data transmission delay of no more than 3 seconds.

[0039] When the communication network is functioning normally, data is uploaded to the external terminal in real time. When the communication network is interrupted, the data is automatically cached in the local storage module 33 and automatically retransmitted after communication is restored, ensuring the integrity of the data sequence. Data marked as abnormal transitions is only stored in the local storage module 33 and is not sent out through the communication module 34.

[0040] In this embodiment of the application, the online monitoring method for carbon dioxide in flue gas further includes zero-point calibration and / or range calibration of the sensor for detecting carbon dioxide concentration; the zero-point calibration is performed using high-purity nitrogen, and the range calibration is performed using a standard gas.

[0041] Specifically, the high-purity nitrogen generator (purity not less than 99.999%) built into the zero-point calibration module 61 automatically introduces nitrogen into the gas detection chamber at a preset cycle (e.g., every morning) to perform zero-point calibration on the carbon dioxide sensor 21. The standard gas interface of the range calibration module 62 allows operators to connect standard carbon dioxide gas of known concentration to perform range calibration on the sensor at a preset cycle (e.g., every 3 months). Calibration can be triggered remotely or performed manually on-site.

[0042] This application provides an online monitoring device for carbon dioxide in flue gas, such as... Figure 1As shown, the device employs the aforementioned online monitoring method for carbon dioxide in flue gas, and includes a sampling pretreatment unit 1, a detection unit 2, a data processing unit 3, and a protective housing 4.

[0043] The sampling preprocessing unit 1 is used to perform step S1. The sampling preprocessing unit 1 includes a sampling probe 11, a filter assembly 13, a condenser assembly 14 and a gas-liquid separation assembly 15 arranged sequentially along the gas path, as well as a suction pump 16 for providing suction power. A heat tracing assembly 12 is also provided in the gas path for heat tracing and heat preservation of the flue gas during the process of the flue gas being transferred from the sampling probe 11 to the condenser assembly 14.

[0044] Specifically, the sampling probe 11 is a high-temperature resistant stainless steel probe with a built-in stainless steel sintered filter screen with a pore size of 5μm~10μm, used for initial interception of large dust particles. The heat tracing assembly 12 is an electric heat tracing and insulation pipe, with a constant heat tracing temperature of 120℃~150℃ to prevent water vapor condensation during flue gas transmission. The filtration assembly 13 includes a primary filter 131 and a precision filter 132 arranged in series. The primary filter 131 is a bag filter with a filtration accuracy of 2μm~5μm, and the precision filter 132 is a microporous membrane filter with a filtration accuracy of 0.1μm~0.5μm. Together, they achieve dual filtration of dust and oil. The suction pump 16 is a corrosion-resistant diaphragm pump, providing stable suction power to ensure a stable flow rate of flue gas in the gas path.

[0045] The detection unit 2 is connected to the sampling preprocessing unit 1 and is used to execute S2. The detection unit 2 is equipped with a carbon dioxide sensor 21, a temperature sensor 22, a humidity sensor 23 and a pressure sensor 24.

[0046] The gas detection chamber is a sealed cavity with an internal gas flow equalization plate, ensuring that the pretreated flue gas passes evenly through the sensor detection area and avoiding fluctuations in detection data caused by flue gas eddies. The carbon dioxide sensor 21 is a non-dispersive infrared sensor with a measurement range of 0~50000ppm, a measurement accuracy of ±1%FS, and a response time of no more than 5s. Temperature sensor 22, humidity sensor 23, and pressure sensor 24 are integrated with the carbon dioxide sensor 21, acquiring the temperature, humidity, and pressure parameters of the flue gas within the detection chamber in real time at a frequency of 1 time / second.

[0047] The data processing unit 3 is electrically connected to the detection unit 2 and is used to execute S3 and S4. The data processing unit 3 includes a compensation and correction module 31 and a data verification module 32.

[0048] The data processing unit 3 includes a microprocessor 35, a local storage module 33, and a communication module 34. The microprocessor 35 incorporates a temperature, humidity, and pressure compensation algorithm to perform real-time compensation and correction of carbon dioxide concentration. The data verification module 32 performs threshold and trend verification on the compensated and corrected data, identifying and eliminating abnormally fluctuating data. The local storage module 33 is a non-volatile storage module with a storage capacity of no less than 128GB, capable of storing at least one year's worth of raw monitoring data, compensated data, equipment operation data, and early warning and handling data. Data is cached during communication interruptions and automatically retransmitted after communication is restored. Abnormally fluctuating data is stored in the local storage module 33 and is not transmitted externally through the communication module 34. The communication module 34 uses 4G / 5G and LoRa dual-mode communication. For short distances, it communicates with the enterprise's local monitoring terminal via LoRa; for long distances, it communicates with the park's carbon emission monitoring platform via the 4G / 5G public network, with a data transmission latency of no more than 3 seconds.

[0049] The protective housing 4 is made of stainless steel, with explosion-proof and corrosion-resistant properties and a fluorocarbon coating. Its protection level is no less than IP67, providing dustproof, sandproof, and corrosion-resistant performance. At least some components of the sampling pretreatment unit 1 (e.g., filter assembly 13, condensation assembly 14, gas-liquid separation assembly 15, and air pump 16), the detection unit 2 (gas detection chamber and internal sensors), and the data processing unit 3 are housed inside the protective housing 4, forming a sealed dustproof space to prevent external sand and dust from entering the equipment.

[0050] In this embodiment, the inner wall of the protective housing 4 is provided with a heat insulation layer, which is an aluminum silicate heat insulation layer, used to maintain the internal working temperature of the protective housing 4 within a preset temperature range of -20℃ to 60℃, so as to ensure that the internal electronic components work normally in high temperature and cold environments.

[0051] In this embodiment, the flue gas carbon dioxide online monitoring device further includes a cleaning unit 5. The cleaning unit 5 is connected to the gas path of the sampling pretreatment unit 1 and / or the gas path of the detection unit 2, and is used to introduce clean gas into the gas path to remove dust or impurities accumulated in the gas path.

[0052] The cleaning unit 5 includes a gas backflushing unit. The gas backflushing unit is connected to the gas pipeline of the sampling pretreatment unit 1 and communicates with the sampling probe 11 and the gas detection chamber of the detection unit 2. It is used to introduce cleaning gas into the sampling probe 11, the gas detection chamber, and the gas pipeline to remove dust or impurities accumulated in these areas. The gas backflushing unit automatically starts according to a preset cycle (e.g., once every 2 hours) or can be activated in response to remote or on-site commands, achieving automatic cleaning of the gas path and preventing pipeline blockage.

[0053] The backflushing unit can use high-pressure nitrogen or compressed air as the cleaning gas, with a purging pressure of 0.3MPa~0.5MPa. When the backflushing unit is activated, the cleaning gas flows in the reverse direction along the gas pipeline, purging the filter screen built into the sampling probe 11, the inner wall of the gas detection chamber and the sensor detection surface, as well as the inner wall of each section of the gas pipeline. This removes dust and impurities adhering to these parts and discharges them with the airflow, thereby restoring the unobstructed state of the gas path.

[0054] It should be noted that the connection between the gas path backflush unit and the gas path pipeline of the sampling pretreatment unit 1 means that the gas path backflush unit is connected to the main gas path of the sampling pretreatment unit 1 through a branch pipeline, and a control valve is installed on this branch pipeline. During normal sampling, this control valve is closed, isolating the gas path backflush unit from the main gas path, and the suction pump 16 operates normally to draw flue gas from the sampling probe 11. When gas path cleaning is required, the control valve opens, and the suction pump 16 stops working or reduces its power. Cleaning gas enters the main gas path through this branch pipeline to backflush the sampling probe 11, the gas detection chamber, and the gas path pipeline. After cleaning is completed, the control valve closes, and the suction pump 16 resumes normal operation.

[0055] In this embodiment, the online monitoring device for carbon dioxide in flue gas further includes a calibration unit 6. The calibration unit 6 is connected to the detection unit 2 and is used to perform zero-point calibration and / or range calibration on the detection unit 2; the calibration unit 6 includes a zero-point calibration module 61 and a range calibration module 62.

[0056] The zero-point calibration module 61 has a built-in nitrogen generator that can produce nitrogen gas with a purity of not less than 99.999%. Nitrogen gas is automatically introduced into the gas detection chamber at a preset cycle (such as early morning every day) to perform zero-point calibration on the carbon dioxide sensor 21.

[0057] The range calibration module 62 is equipped with a standard gas interface for connecting standard carbon dioxide gas of known concentration, and performs range calibration on the carbon dioxide sensor 21 by remote command or on-site manual means according to a preset cycle (such as every 3 months).

[0058] In this embodiment of the application, the data processing unit 3 further includes a communication module 34 and a local storage module 33; the communication module 34 is used to send carbon dioxide monitoring data to an external terminal, and the local storage module 33 is used to cache carbon dioxide monitoring data when communication is interrupted and automatically retransmit it after communication is restored; when the data verification module 32 determines that the current carbon dioxide concentration data is abnormal jump data, the abnormal jump data is stored in the local storage module 33 and is not sent out through the communication module 34.

[0059] In this embodiment of the application, the flue gas carbon dioxide online monitoring device further includes a power supply unit 7, which provides working power to the sampling pretreatment unit 1, the detection unit 2, the data processing unit 3, the cleaning unit 5, and the calibration unit 6.

[0060] Specifically, the power supply unit 7 includes a mains power supply module 71 and a backup power supply module 72. The mains power supply module 71 is a 220V AC mains input, adapted to industrial field power supply environments, and converts AC power to the DC operating voltage required by each unit through a power conversion circuit. The backup power supply module 72 is a rechargeable lithium battery pack with a capacity of not less than 100Ah, connected in parallel with the mains power supply module 71 and equipped with an automatic transfer switch. When the mains power supply is normal, the mains power supply module 71 supplies power to each unit of the device and simultaneously charges the backup power supply module 72; when the mains power fails, the automatic transfer switch activates instantaneously, switching the power source to the backup power supply module 72. The backup power supply module 72 can ensure that the device can operate continuously for no less than 8 hours without mains power, ensuring that monitoring work is not interrupted due to power outages.

[0061] The power supply unit 7 is also equipped with a power monitoring module 73 and a power outage alarm module 74. The power monitoring module 73 monitors the mains power supply status and the remaining power of the backup power module 72 in real time. When the power of the backup power module 72 falls below a preset threshold, it sends a low power warning signal to the data processing unit 3. The power outage alarm module 74 is automatically triggered when the mains power fails, sending a power outage alarm signal to the data processing unit 3. The data processing unit 3 then uploads the power outage alarm information to an external terminal via the communication module 34, notifying management personnel to handle the situation promptly. After the mains power is restored, the power supply unit 7 automatically switches back to mains power supply mode and simultaneously resumes charging of the backup power module 72.

[0062] The online carbon dioxide monitoring device for flue gas is installed in a monitoring station next to the emission source flue, with the sampling probe 11 inserted into the upper part of the flue. Upon startup, the suction pump 16 draws the high-temperature flue gas from the flue into the sampling probe 11, which is then heated and insulated by the heating assembly 12 before being transported to the filter assembly 13 for dust and oil removal. After cooling by the condensation assembly 14 and dehydration by the gas-liquid separation assembly 15, pre-treated flue gas is obtained. The pre-treated flue gas enters the gas detection chamber, where the carbon dioxide sensor 21 detects the carbon dioxide concentration. The temperature sensor 22, humidity sensor 23, and pressure sensor 24 simultaneously collect environmental parameters. The microprocessor 35 performs real-time compensation and correction of the carbon dioxide concentration based on the temperature, humidity, and pressure parameters. The data verification module 32 performs threshold and trend verification, and after removing abnormal data, valid data is uploaded to an external terminal via the communication module 34. During device operation, the calibration unit 6 automatically performs sensor calibration according to a preset cycle, the cleaning unit 5 automatically performs gas path purging according to a preset cycle, and the backup power module 72 of the power supply unit 7 automatically switches power supply when the mains power is interrupted, achieving unattended continuous operation.

[0063] In a specific application scenario, this device was installed at the boiler emission source of a new energy enterprise in an industrial park. The flue gas temperature was approximately 600℃, and the dust concentration was high. The device parameters were set as follows: carbon dioxide sensor 21 with a range of 0~50000ppm, sampling frequency 1 time / second, heating temperature 130℃, condenser temperature 25℃, purging frequency every 2 hours, zero-point calibration performed daily at midnight, range calibration performed every 3 months, and the carbon dioxide concentration warning threshold set at 30000ppm. The device operated continuously for 6 months without any issues such as gas path blockage or sensor malfunction. The monitoring data was stable, and the measurement accuracy after compensation reached ±0.8%FS. Data was not lost during network outages due to local caching. When the concentration exceeded the limit, it could provide dual notifications: on-site audible and visual alarms and remote platform warnings, fully meeting the needs of enterprise carbon accounting and industrial park carbon emission control.

[0064] In another specific application scenario, this device was installed at the emission source of a kiln in a chemical plant. The flue gas temperature was approximately 750℃, containing a small amount of oil. The device parameters were set as follows: carbon dioxide sensor 21 with a range of 0~50000ppm, sampling frequency 1 time / second, heating temperature 150℃, condenser temperature 30℃, purging frequency once per hour, zero-point calibration performed daily at midnight, range calibration performed every 3 months, and the carbon dioxide concentration warning threshold set at 35000ppm. The device operated continuously for 8 months with stable performance, achieving a dehydration efficiency of 99.2% and a dust filtration efficiency of 99.8%. There were no issues with oil or dust clogging, and the monitoring data was accurate, providing reliable data analysis for the company's carbon emission reduction process adjustments.

[0065] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0066] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application 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 therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A method for online monitoring of carbon dioxide in flue gas, characterized in that, include: S1: Collect the flue gas emitted from the emission source and remove impurities from the flue gas to obtain pretreated flue gas; S2: Detect the carbon dioxide concentration in the pretreated flue gas, and simultaneously collect the temperature, humidity and pressure of the pretreated flue gas; S3: The carbon dioxide concentration is compensated and corrected in real time based on the temperature, humidity and pressure to eliminate the impact of environmental parameter fluctuations on detection accuracy; S4: Perform data validity verification on the carbon dioxide concentration data after compensation and correction in step S3. The data validity verification includes threshold verification and trend verification. The threshold verification is used to determine whether a single data point exceeds a preset threshold range. The trend verification is used to determine whether the changing trend of multiple consecutive data points exceeds a preset change rate range, so as to identify and remove abnormal jump data. as well as, S5: Output the carbon dioxide monitoring data after the compensation correction and data verification.

2. The method for online monitoring of carbon dioxide in flue gas according to claim 1, characterized in that, In step S1, the flue gas is heated and kept warm before being transferred from the sampling point to the condensation treatment stage, and then sequentially undergoes filtration and dust removal, condensation and cooling treatment, and gas-liquid separation to remove condensate.

3. The method for online monitoring of carbon dioxide in flue gas according to claim 1, characterized in that, It also includes step S6: performing zero-point calibration and / or range calibration on the sensor for detecting the carbon dioxide concentration; the zero-point calibration is performed using high-purity nitrogen, and the range calibration is performed using a standard gas.

4. The method for online monitoring of carbon dioxide in flue gas according to claim 1, characterized in that, In step S5, when communication is normal, the carbon dioxide monitoring data is sent to an external terminal via a wireless network; when communication is interrupted, the carbon dioxide monitoring data is cached locally and automatically retransmitted after communication is restored; the abnormal jump data is stored locally and not sent out.

5. An online monitoring device for carbon dioxide in flue gas, characterized in that, The method for online monitoring of carbon dioxide in flue gas according to any one of claims 1 to 4 includes: The sampling preprocessing unit (1) is used to perform step S1. The sampling preprocessing unit (1) includes a sampling probe (11), a filter assembly (13), a condensation assembly (14) and a gas-liquid separation assembly (15) arranged sequentially along the gas path, as well as a suction pump (16) for providing suction power. A heat tracing assembly (12) is also provided in the gas path for heat tracing and heat preservation of the flue gas during the process of the flue gas being transferred from the sampling probe (11) to the condensation assembly (14). The detection unit (2) is connected to the sampling preprocessing unit (1) and is used to execute S2. The detection unit (2) is equipped with a carbon dioxide sensor (21), a temperature sensor (22), a humidity sensor (23) and a pressure sensor (24). A data processing unit (3), electrically connected to the detection unit (2), is used to execute S3 and S4. The data processing unit (3) includes a compensation and correction module (31) and a data verification module (32); and, The protective housing (4) houses at least some components of the sampling preprocessing unit (1), the detection unit (2), and the data processing unit (3).

6. The online monitoring device for carbon dioxide in flue gas according to claim 5, characterized in that, The inner wall of the protective housing (4) is provided with a heat insulation layer to maintain the working temperature inside the protective housing (4) within a preset temperature range.

7. The online monitoring device for carbon dioxide in flue gas according to claim 5, characterized in that, It also includes a cleaning unit (5); The cleaning unit (5) is connected to the gas path of the sampling pretreatment unit (1) and / or the gas path of the detection unit (2) to introduce cleaning gas into the gas path to remove dust or impurities accumulated in the gas path.

8. The online monitoring device for carbon dioxide in flue gas according to claim 5, characterized in that, It also includes a calibration unit (6); The calibration unit (6) is connected to the detection unit (2) and is used to perform zero-point calibration and / or range calibration on the detection unit (2); The calibration unit (6) includes a zero-point calibration module (61) and a range calibration module (62). The zero-point calibration module (61) has a built-in nitrogen generator for zero-point calibration of the detection unit (2). The range calibration module (62) is provided with a standard gas interface for connecting standard gas to perform range calibration of the detection unit (2).

9. The online monitoring device for carbon dioxide in flue gas according to claim 5, characterized in that, The data processing unit (3) further includes a communication module (34) and a local storage module (33); the communication module (34) is used to send the carbon dioxide monitoring data to an external terminal, and the local storage module (33) is used to cache the carbon dioxide monitoring data when communication is interrupted and automatically retransmit it after communication is restored; when the data verification module (32) determines that the current carbon dioxide concentration data is abnormal jump data, the abnormal jump data is stored in the local storage module (33) and is not sent out through the communication module (34).

10. The online monitoring device for carbon dioxide in flue gas according to claim 7, characterized in that, The cleaning unit (5) includes a gas backflush unit, which is connected to the sampling probe (11), the gas detection chamber of the detection unit (2), and the gas pipeline of the sampling pretreatment unit (1), respectively. The gas backflush unit is activated according to a preset cycle or in response to an external command to clean the gas path.

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