Methods for calibrating the accuracy of online mercury measurement systems

Abstract

This invention discloses a method for calibrating the accuracy of an online mercury measurement system, including a dilution ratio self-calibration method S1: Step S101: A built-in mercury generator produces mercury-free zero gas, which is diluted by a dilution sampling component according to a set dilution ratio and then introduced into a mercury analyzer for measurement; Step S102: A calibration concentration and calibration gas volume are set. The built-in mercury generator produces a standard gas with the calibration concentration, and the standard gas is diluted by the dilution sampling component according to the set dilution ratio based on the calibration gas volume, and then introduced into the mercury analyzer for measurement; Step S103: The zero-value error is calculated. If the zero-value error is greater than the maximum threshold for zero-value error, the mercury analyzer is checked to eliminate zero-point drift; Step S104: The relative error of the diluted standard gas is calculated. If the relative error of the diluted standard gas is greater than the maximum threshold for relative error of the diluted standard gas, an abnormality in the dilution sampling component is checked. By optimizing the calibration method for gaseous elemental mercury in diluted sampling, the accuracy of the online mercury measurement results is ensured.

Description

Technical Field

[0001] This invention relates to the field of mercury monitoring technology, and in particular to a method for calibrating the accuracy of an online mercury measurement system. Background Technology

[0002] Online monitoring of mercury emissions from stationary sources is a prerequisite for effective control, while reliable system self-calibration is the foundation for accurate measurement. In related technologies, the mercury measurement process ultimately transforms into the measurement of gaseous elemental mercury. Therefore, it is necessary to generate a standard gas of a standard concentration using an elemental mercury generator to verify the accuracy of the gaseous elemental mercury measurement results. Direct sampling measurement methods simply require passing the standard gas into the analyzer for measurement to complete the calibration. However, because mercury measurement is easily affected by other components in the flue gas, unlike the direct sampling method used for conventional flue gas component measurements, mercury measurement generally employs dilution sampling. For dilution measurements, the original flue gas pollutant concentration = the diluted analyzer measurement result × the dilution ratio. Therefore, it is necessary to understand the accuracy of the analyzer and determine the dilution ratio to ensure the accuracy and reliability of the measurement results. However, current calibration methods for dilution sampling instruments cannot achieve perfect precision, easily leading to distorted measurement results. Summary of the Invention

[0003] This invention is based on the inventor's discoveries and understanding of the following facts and problems:

[0004] Current dilution sampling instruments cannot be calibrated separately; instead, they still rely on direct sampling measurements, directly introducing standard gas into the sampler inlet and treating the entire system as a black box, simply correcting the measurement results with a single coefficient. While simple and convenient, this approach easily overlooks potential problems. For example, when there are deviations in the standard gas concentration, blockages in the diluent, or drift in the analyzer, because these issues are not effectively recognized, users will still only correct a single coefficient after calibration, leading to distorted measurement results.

[0005] This invention aims to at least partially address one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for calibrating the accuracy of an online mercury measurement system. By optimizing the calibration method for diluted gaseous elemental mercury samples, the accuracy of online mercury measurement results is ensured.

[0006] This invention relates to a method for calibrating the accuracy of an online mercury measurement system, wherein the online mercury measurement system includes a dilution sampling component, a built-in mercury generator, and a mercury analyzer, and the method includes a dilution ratio self-calibration method S1:

[0007] Step S101: The built-in elemental mercury generator produces mercury-free zero gas. This mercury-free zero gas is diluted by the dilution sampling component according to a set dilution ratio and then introduced into the mercury analyzer for measurement. Multiple cycles are executed to obtain multiple Hg values. 0 The reading is c0;

[0008] Step S102: Set the calibration concentration and calibration gas volume. The built-in elemental mercury generator produces a standard gas with the calibration concentration. The standard gas is diluted according to the set dilution ratio using the dilution sampling component based on the calibration gas volume, and then introduced into the mercury analyzer for measurement. Multiple cycles are performed to obtain multiple Hg values. 0 The reading is c1;

[0009] Step S103: Calculate the zero error according to the formula zero error = mean c0 × dilution ratio. If the zero error is greater than the maximum threshold of zero error, check the mercury analyzer to eliminate zero drift.

[0010] Step S104: Calculate the relative error of the diluted standard gas according to the formula: relative error of diluted standard gas = (mean of c1 × dilution ratio - calibration concentration) ÷ calibration concentration. If the relative error of the diluted standard gas is greater than the maximum threshold of the relative error of the diluted standard gas, check the abnormality of the dilution sampling component.

[0011] The method for calibrating the accuracy of an online mercury measurement system according to embodiments of the present invention optimizes the calibration method for gaseous elemental mercury sampled in a diluted manner, effectively and accurately identifies abnormal components and factors in the online mercury measurement system, and performs targeted calibration to ensure the accuracy of the online mercury measurement results.

[0012] In some embodiments, the dilution ratio self-calibration method S1 includes step S105: directly introducing the standard gas from step S102 into the mercury analyzer according to the calibration gas volume for measurement, performing multiple cycles, and obtaining multiple Hg values. 0 The reading is c2.

[0013] In some embodiments, step S105 further includes:

[0014] The relative error of the direct-through standard gas is calculated according to the formula: (mean of c2 - calibration concentration) ÷ calibration concentration. If the relative error of the direct-through standard gas is greater than the maximum threshold of the relative error of the direct-through standard gas, an external calibration elemental mercury generator is used to generate standard gas with a concentration of the calibration concentration. The standard gas is then directly passed to the mercury analyzer for measurement according to the calibration gas volume. The analysis determines whether the problem is with the mercury analyzer or the built-in elemental mercury generator.

[0015] In some embodiments, in step S104: if it is determined that the relative error of the dilution standard gas is greater than the maximum threshold of the relative error of the dilution standard gas, and it is determined that the relative error of the direct standard gas is within the normal range, check the abnormality of the dilution sampling component. Checking the dilution sampling component includes checking whether gas path blockage has occurred and checking its temperature control module.

[0016] In some embodiments, step S105 further includes: calculating the theoretical dilution ratio according to the formula Theoretical dilution ratio = mean c2 ÷ mean c1; if the fluctuation value of the theoretical dilution ratio is greater than the fluctuation threshold, checking for abnormalities in the dilution sampling component.

[0017] In some embodiments, in step S101: n0 cycles are performed using the mercury-free zero gas, where n0 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading is c0; in step S102: the standard gas is used to perform n1 cycles, where n1 is greater than 4, and the value of the last 4 cycles is taken as Hg. 0 Indicator c1; Step S103: Perform n2 cycles using the standard gas, where n2 is greater than 2, and take the value of the last 2 cycles as Hg. 0 The reading is c2.

[0018] In some embodiments, a linear calibration method S2 is also included:

[0019] Step S201: The built-in elemental mercury generator produces mercury-free zero gas. This mercury-free zero gas is diluted by the dilution sampling component according to a set dilution ratio and then introduced into the mercury analyzer for measurement. Multiple cycles are executed to obtain multiple Hg values. 0 The reading is C0;

[0020] Step S202: Select n calibration concentrations within the range of the mercury analyzer, where n≥3. The built-in elemental mercury generator sequentially generates standard gas according to the calibration concentrations. The generated standard gas is then diluted according to the set dilution ratio using the dilution sampling component based on the calibration gas volume, and then introduced into the mercury analyzer for measurement. This process is repeated multiple times to obtain multiple sets of Hg values. 0 The readings, each group including multiple Hg values. 0 Display C i i = 1 to n;

[0021] Step S203: Calculate Hg 0 The result Y0 is calculated by multiplying the mean reading C0 by the dilution ratio, and the Hg for each group. 0 Display C i The result of calculating Y: mean × dilution ratio i , Y0 and Y i Perform linear fitting, calculate the slope k and intercept b, and base the results on the theoretical value X0 at the zero point and the theoretical values ​​X at several calibration concentrations. iAccording to formula Z i =k*X i +b, calculate the regression value Z i And according to formula D i =ABS(Z) i -X i ) / X i Calculate the linearity error D i Take D i The maximum value is Hg 0 Linear relative error;

[0022] If the linear relative error is greater than the maximum threshold of the linear relative error, check for abnormalities in the built-in elemental mercury generator and the mercury analyzer.

[0023] In some embodiments, the linear calibration method S2 further includes step S204: using an external calibration elemental mercury generator to sequentially generate standard gas of the same concentration as in step S202, and diluting the generated standard gas according to a set dilution ratio based on the calibration gas volume, and then passing it into a mercury analyzer for measurement, and analyzing and determining whether the malfunction is due to the mercury analyzer or the built-in elemental mercury generator.

[0024] In some embodiments, in step S203:

[0025] If the linear relative error is determined to be greater than the maximum threshold of linear relative error, and the relative error of the diluted standard gas is determined to be within the normal range, check for any abnormalities in the built-in elemental mercury generator and the mercury analyzer.

[0026] In some embodiments, in step S201: n0 cycles are performed using the mercury-free zero gas, where n0 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading is C0;

[0027] In step S202: several standard gases are used to perform n3 cycles sequentially, where n3 is greater than 4, and the value of the last 4 cycles is taken as Hg. 0 Display C i . Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the online mercury measurement system according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic flowchart of the dilution ratio self-calibration method S1 in the method for calibrating the accuracy of an online mercury measurement system according to an embodiment of the present invention.

[0030] Figure 3 This is a flowchart illustrating the linear calibration method S2 in the method for calibrating the accuracy of an online mercury measurement system according to an embodiment of the present invention.

[0031] Figure label:

[0032] Elemental mercury online measurement system 100, dilution sampling component 1, built-in elemental mercury generator 2, mercury analyzer 3, calibration elemental mercury generator 4, electromagnetic shut-off valve 5, electromagnetic three-way valve 6, manual shut-off valve 7, manual three-way valve 8. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, with examples of the embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] The following is based on Figures 1-3 This invention describes a method for calibrating the accuracy of an online mercury measurement system according to embodiments of the present invention. For example... Figure 1 As shown, the online mercury element measurement system 100 includes a dilution sampling component 1, a built-in mercury element generator 2, and a mercury analyzer 3. The method provided in this embodiment of the invention is used to calibrate the accuracy of the online measurement results of the online mercury element measurement system 100. This method includes a dilution ratio self-calibration method S1:

[0035] Step S101: The built-in elemental mercury generator 2 generates mercury-free zero gas. The mercury-free zero gas is diluted by the dilution sampling component 1 according to the set dilution ratio and then introduced into the mercury analyzer 3 for measurement. Multiple cycles are executed to obtain multiple Hg values. 0 The reading is c0;

[0036] Step S102: Set the calibration concentration and calibration gas volume. The built-in elemental mercury generator 2 generates a standard gas with the calibration concentration. According to the calibration gas volume, the standard gas is diluted by the dilution sampling component 1 according to the set dilution ratio, and then introduced into the mercury analyzer 3 for measurement. Multiple cycles are executed to obtain multiple Hg values. 0 The reading is c1;

[0037] Step S103: According to the formula:

[0038] Zero error = mean c0 × dilution ratio

[0039] Calculate the zero-value error. If the zero-value error is greater than the maximum threshold for zero-value error, check the mercury analyzer 3 and eliminate zero-point drift.

[0040] Step S104: According to the formula:

[0041] Relative error of diluted standard gas = (mean c1 × dilution ratio - calibration concentration) ÷ calibration concentration

[0042] Calculate the relative error of the diluted standard gas. If the relative error of the diluted standard gas is greater than the maximum threshold of the relative error of the diluted standard gas, check for abnormalities in the dilution sampling component 1.

[0043] It should be noted that the "dilution ratio" used in step S103 when calculating the zero-value error is the set dilution ratio of the dilution sampling component 1. If the zero-value error is determined to be large in step S103, exceeding the maximum threshold of the zero-value error setting range, it is determined that the analytical accuracy of the mercury analyzer 3 is problematic, resulting in zero-point drift. Therefore, the mercury analyzer 3 is calibrated to eliminate the zero-point drift and ensure the measurement accuracy of the online mercury element measurement system 100.

[0044] In step S104, the "dilution ratio" used to calculate the relative error of the diluted standard gas is the set dilution ratio of the dilution sampling component 1, and the "calibration concentration" is the concentration of the standard gas set in step S102, i.e., the theoretical concentration of the standard gas. If, in step S104, the relative error of the diluted standard gas is determined to be large, exceeding the maximum threshold of the set range, it is determined that the dilution accuracy of the dilution sampling component 1 is abnormal, causing a deviation between the actual dilution ratio and the set dilution ratio. Therefore, the dilution sampling component 1 is calibrated to eliminate the dilution ratio deviation and ensure the measurement accuracy of the online mercury measurement system 100. For example, this can be achieved by focusing on checking the gas path and temperature control of the dilution sampling component 1, and, if necessary, disassembling it to check for blockages, thus eliminating the deviation.

[0045] The method for calibrating the accuracy of an online mercury measurement system according to embodiments of the present invention optimizes the calibration method for gaseous elemental mercury sampled in a diluted manner, effectively and accurately identifies abnormal components and factors in the online mercury measurement system, and performs targeted calibration to ensure the accuracy of the online mercury measurement results.

[0046] In some embodiments, the dilution ratio self-calibration method S1 further includes step S105: the standard gas generated by the built-in elemental mercury generator 2 in step S102 is directly introduced into the mercury analyzer 3 for measurement according to the calibration gas volume, and multiple cycles are performed to obtain multiple Hg values. 0 The reading is c2.

[0047] Furthermore, step S105 also includes: according to the formula:

[0048] The relative error of the direct-pass standard gas = (mean c2 - calibration concentration) ÷ calibration concentration.

[0049] Calculate the relative error of the direct-pass standard gas. If the relative error of the direct-pass standard gas is greater than the maximum threshold of the relative error of the direct-pass standard gas, use an external calibration elemental mercury generator 4 to generate standard gas with a concentration of the calibration concentration, and measure the standard gas directly through the mercury analyzer 3 according to the calibration gas volume. Analyze and determine whether the abnormality is of the mercury analyzer 3 or the internal elemental mercury generator 2.

[0050] Specifically, in step S105, the "calibration concentration" used to calculate the relative error of the direct-flow standard gas is the concentration of the standard gas set in step S102, i.e., the theoretical concentration of the standard gas. If, in step S105, it is determined that the relative error of the direct-flow standard gas is large, exceeding the maximum threshold of the set range for the relative error of the direct-flow standard gas, it is determined that there is a problem with the measurement accuracy of the mercury analyzer 3 or the standard gas generation accuracy of the built-in elemental mercury generator 2. Since the standard gas is direct-flow in step S105 and is not diluted by the dilution sampling component 1, it is impossible to determine whether the dilution sampling component 1 is malfunctioning.

[0051] To further analyze and determine whether the malfunction is in the mercury analyzer 3 or the built-in elemental mercury generator 2, an external calibration elemental mercury generator 4 is needed to accurately generate standard gas. Specifically, the external calibration elemental mercury generator 4 generates standard gas with a concentration equal to the calibration concentration, and the standard gas is directly fed into the mercury analyzer 3 for measurement according to the calibration gas volume. This process is repeated multiple times to obtain multiple Hg values. 0 The reading c' is given by the formula:

[0052] Relative error of direct-pass standard gas = (mean c' - calibration concentration) ÷ calibration concentration

[0053] Calculate the relative error of the direct-through standard gas of the calibration mercury generator 4. If analysis reveals that the relative error of the direct-through standard gas of the built-in mercury generator 2 is close to that of the calibration mercury generator 4, it indicates that the accuracy of the standard gas generation by the built-in mercury generator 2 and the calibration mercury generator 4 is close and within a reasonable range. Therefore, the built-in mercury generator 2 is deemed normal, while the analytical accuracy of the mercury analyzer 3 is abnormal. Calibration of the mercury analyzer 3 is then used to calibrate the measurement accuracy of the online mercury measurement system 100. Conversely, if analysis reveals a significant difference between the relative error of the direct-through standard gas of the built-in mercury generator 2 and the calibration mercury generator 4, and the relative error of the direct-through standard gas of the calibration mercury generator 4 is within a reasonable range, it indicates that the mercury analyzer 3 is normal, while the standard gas generation by the built-in mercury generator 2 is abnormal. Calibration of the measurement accuracy of the online mercury measurement system 100 is then used to calibrate the measurement accuracy of the built-in mercury generator 2.

[0054] In some embodiments, in step S104: if it is determined that the relative error of the dilution standard gas is greater than the maximum threshold for the relative error of the dilution standard gas, and it is determined that the relative error of the direct-flow standard gas is within the normal range, then the focus is on checking for any abnormalities in the dilution sampling component 1. Checking the dilution sampling component 1 includes checking whether gas path blockage has occurred and checking its temperature control module. That is, in order to improve the accuracy of calibration, in step S104, after determining that the relative error of the dilution standard gas is greater than the maximum threshold for the relative error of the dilution standard gas, it is simultaneously determined whether the relative error of the direct-flow standard gas is within the normal range. If it is determined that the relative error of the direct-flow standard gas is within the normal range, and the abnormality of the built-in elemental mercury generator 2 is ruled out, then the focus of calibration is placed on the dilution sampling component 1, thereby improving the accuracy and efficiency of calibration.

[0055] Furthermore, step S105 also includes: according to the formula:

[0056] Theoretical dilution ratio = mean c2 ÷ mean c1

[0057] Calculate the theoretical dilution ratio. If the fluctuation value of the theoretical dilution ratio exceeds the fluctuation threshold, check for abnormalities in dilution sampling component 1. Specifically, set a maximum theoretical fluctuation threshold for the theoretical dilution ratio. If, after calculation, the theoretical dilution ratio of the online mercury element measurement system 100 exceeds the maximum theoretical fluctuation threshold, it is determined that the dilution accuracy of dilution sampling component 1 is abnormal, causing a large fluctuation in the theoretical dilution ratio. Therefore, by calibrating dilution sampling component 1, the dilution ratio deviation is eliminated, ensuring the measurement accuracy of the online mercury element measurement system 100. For example, focus on checking the gas path and temperature control of dilution sampling component 1; if necessary, disassemble it to check for blockages and eliminate deviations.

[0058] To improve the accuracy of the calculation, in some specific embodiments, in step S101: n0 cycles are performed using mercury-free zero gas, where n0 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading is c0; in step S102: standard gas is used to perform n1 cycles, where n1 is greater than 4, and the value of the last 4 cycles is taken as Hg. 0 Indicator c1; In step S103: Standard gas is used to perform n2 cycles, where n2 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading c2, by removing non-steady-state data, improves the reliability and accuracy of the calculation results.

[0059] The following is based on Figure 1 The illustrated online mercury measurement system 100 describes a method for calibrating the accuracy of the online mercury measurement system according to an embodiment of the present invention.

[0060] The online mercury element measurement system 100 includes a dilution sampling component 1, a built-in mercury element generator 2, a mercury analyzer 3, an electromagnetic shut-off valve 5, and an electromagnetic three-way valve 6. In addition, a calibration mercury element generator 4, a manual shut-off valve 7, and a manual three-way valve 8 are also provided outside the online mercury element measurement system 100. The built-in mercury element generator 2 is connected to the dilution sampling component 1 and the mercury analyzer 3 via the electromagnetic three-way valve 6. Gas path A of the electromagnetic three-way valve 6 connects to the dilution sampling component 1, and gas path B connects to the mercury analyzer 3. The outlet side of the mercury element generator 2 is equipped with the electromagnetic shut-off valve 5. The calibration mercury element generator 4 is an external mercury element generator, which is connected to both the dilution sampling component 1 and the mercury analyzer 3 via the manual three-way valve 8. The outlet side of the calibration mercury element generator 4 is equipped with the manual shut-off valve 7.

[0061] It is understood that in other embodiments, the calibration elemental mercury generator 4 can also be connected to the dilution sampling assembly 1 and the mercury analyzer 3 via an electromagnetic three-way valve, and an electromagnetic shut-off valve can be used on the outlet side. The built-in elemental mercury generator 2 is connected to the dilution sampling assembly 1 and the mercury analyzer 3 via a manual three-way valve, and a manual shut-off valve can be used on the outlet side.

[0062] The dilution ratio self-calibration method S1 specifically includes:

[0063] Step S100: Execute the sampling gun backflushing procedure until the backflushing is completed;

[0064] Step S101: Open the electromagnetic shut-off valve 5 to generate mercury-free zero gas using the built-in elemental mercury generator 2. The electromagnetic three-way valve 6 is set in channel A. The mercury-free zero gas is diluted by the dilution sampling component 1 according to the set dilution ratio and then sampled and measured throughout the entire process, executing n0 cycles (e.g., 4 cycles). The data from the first n0-2 cycles are marked as "zero gas unsteady state" and are not included in the calculation. Only the value of the last 2 cycles is taken as Hg. 0 The reading c0 is used for calculations, and the data is noted as "Zero-valent mercury analysis dilution ratio calibration - zero gas";

[0065] Step S102: Keep the solenoid shut-off valve 5 open and set the calibration concentration (e.g., 5 μg / m³). 3 The calibration gas flow rate (e.g., 10 L / min) is measured using a three-way electromagnetic valve 6 located in channel A. A standard gas with the calibration concentration is generated using a built-in elemental mercury generator 2. The standard gas is then diluted according to the set dilution ratio using a dilution sampling assembly 1 based on the calibration gas flow rate. This process is repeated for n1 cycles (e.g., 6 cycles). Data from the first n1-4 cycles is noted as "standard gas is not in a steady state" and is not included in the calculation; only the values ​​from the last 4 cycles are used for Hg. 0 The reading c1 is used for calculation, and the data is noted as "Zero-valent mercury analysis dilution ratio calibration - standard gas inlet probe";

[0066] Step S103: According to the formula:

[0067] Zero error = mean c0 × dilution ratio

[0068] Calculate the zero-value error. If the zero-value error is greater than the maximum threshold for zero-value error, check the mercury analyzer 3 and eliminate zero-point drift.

[0069] Step S104: According to the formula:

[0070] Relative error of diluted standard gas = (mean c1 × dilution ratio - calibration concentration) ÷ calibration concentration

[0071] Calculate the relative error of the diluted standard gas. If the relative error of the diluted standard gas is greater than the maximum threshold of the relative error of the diluted standard gas, check for abnormalities in the dilution sampling component 1.

[0072] Step S105: Keep the solenoid shut-off valve 5 open, and set the solenoid three-way valve 6 to channel B. Calibrate the concentration (e.g., 5 μg / m³) as in step S102. 3 The standard gas generated by the built-in mercury generator 2 (e.g., 10 L / min) is directly introduced into the mercury analyzer 3, and n2 cycles (e.g., 3 cycles, adjustable) are executed. The data from the first n2-2 cycles are marked "standard gas is unsteady" and are not included in the calculation. Only the value of the last 2 cycles is taken as Hg. 0 The reading c2 is used for calculation, and the data is noted as "Zero-valent mercury analysis dilution ratio calibration - standard gas into analyzer", according to the formula:

[0073] The relative error of the direct-pass standard gas = (mean c2 - calibration concentration) ÷ calibration concentration.

[0074] Calculate the relative error of the direct-through standard gas. If the relative error of the direct-through standard gas is greater than the maximum threshold of the relative error of the direct-through standard gas, use an external calibration elemental mercury generator 4 to generate standard gas with a concentration of the calibration concentration, open the manual shut-off valve 7, and adjust the manual three-way valve 8 to the side connected to the mercury analyzer 3. Measure the standard gas directly through the mercury analyzer 3 according to the calibration gas volume, and analyze and determine whether the abnormality is of the mercury analyzer 3 or the internal elemental mercury generator 2.

[0075] Alternatively, it can be based on the formula:

[0076] Theoretical dilution ratio = mean c2 ÷ mean c1

[0077] Calculate the theoretical dilution ratio. If the fluctuation value of the theoretical dilution ratio is greater than the fluctuation threshold, check for abnormalities in dilution sampling component 1.

[0078] Step S106: Start mercury-free zero-gas purging, and close the solenoid shut-off valve 5 after purging is completed.

[0079] It should be noted that the order of steps S101-S105 is not restricted.

[0080] like Figure 3 As shown, in some embodiments, the method for calibrating the accuracy of an online mercury measurement system further includes a linear calibration method S2:

[0081] Step S201: The built-in elemental mercury generator 2 generates mercury-free zero gas. The mercury-free zero gas is diluted by the dilution sampling component 1 according to the set dilution ratio and then introduced into the mercury analyzer 3 for measurement. Multiple cycles are executed to obtain multiple Hg values. 0 The reading is C0;

[0082] Step S202: Within the range of the mercury analyzer 3, select n calibration concentrations, n≥3. The built-in elemental mercury generator 2 generates standard gas sequentially according to the calibration concentration. Based on the calibration gas volume, the generated standard gas is diluted by the dilution sampling component 1 according to the set dilution ratio, and then introduced into the mercury analyzer 3 for measurement. This process is repeated for multiple cycles to obtain multiple sets of Hg. 0 The readings, each group including multiple Hg values. 0 Display C i i = 1 to n;

[0083] Step S203: Calculate Hg 0 The result Y0 is calculated by multiplying the mean reading C0 by the dilution ratio, and the Hg for each group. 0 Display C i The result of calculating Y: mean × dilution ratio i , Y0 and Y i Perform linear fitting, calculate the slope k and intercept b, and base the results on the theoretical value X0 at the zero point and the theoretical values ​​X at several calibration concentrations. i According to formula Z i =k*X i +b, calculate the regression value Z i And according to formula D i =ABS(Z) i -X i ) / X i Calculate the linearity error D i Take D i The maximum value is Hg 0 Linear relative error.

[0084] If the linear relative error exceeds the maximum threshold, check for any abnormalities in the built-in mercury generator 2 and the mercury analyzer 3. In other words, if the linear relative error exceeds the maximum threshold of the set range, it is determined that the standard gas generation of the built-in mercury generator 2 or the analytical accuracy of the mercury analyzer 3 is abnormal. The abnormality is eliminated by checking and calibrating to ensure the measurement accuracy of the online mercury measurement system 100.

[0085] Preferably, in step S202, when selecting n calibration concentrations, at least low concentrations typical of stationary source emissions (e.g., 2 μg / m³) are covered. 3 ), medium concentration (e.g., 5 μg / m³) 3 ), high concentration (e.g., 9 μg / m³) 3 Furthermore, the selected n calibration concentrations should cover up to 80%–100% of the mercury analyzer's range 3 to ensure that the linear calibration is representative.

[0086] To accurately distinguish whether the malfunction is caused by the built-in elemental mercury generator 2 or the mercury analyzer 3, in some embodiments, the linear calibration method S2 further includes step S204: using an external calibration elemental mercury generator 4 to sequentially generate standard gas of the same concentration as in step S202, opening the manual shut-off valve 7, and adjusting the manual three-way valve 8 to the side of the dilution sampling component 1, diluting the generated standard gas according to the set dilution ratio based on the calibration gas volume, and then introducing it into the mercury analyzer 3 for measurement, and analyzing and determining whether the malfunction is caused by the mercury analyzer 3 or the built-in elemental mercury generator 2.

[0087] Specifically, the external calibration mercury generator 4 sequentially generates n different calibration concentrations of standard gas as described in step S202. The generated standard gas is then diluted according to a set dilution ratio based on the calibration gas volume and introduced into the mercury analyzer 3 for measurement. Referring to steps S202 and S203, multiple cycles are executed sequentially to obtain multiple sets of Hg. 0 The readings, each group including multiple Hg values. 0 Display C i ', i = 1 to n. Calculate the Hg for each group. 0 Display C i The result of the calculation of mean × dilution ratio Y i ', Y0 and Y i Perform linear fitting, calculate the slope k' and intercept b', and base the results on the theoretical value X0 at the zero point and the theoretical values ​​X at several calibration concentrations. i According to formula Z i '=k'*X i +b', calculate the regression value Z i ', and according to formula D i =ABS(Z) i '-X i ) / X i Calculate the linearity error D i ',take D i The maximum value is Hg 0 Linear relative error.

[0088] If, after analysis, it is found that the linear relative error of the online mercury measurement system 100 calculated in step S203 is close to the linear relative error of the calibration mercury generator 4 calculated in step S204, it indicates that the accuracy of the standard gas generation of the built-in mercury generator 2 and the calibration mercury generator 4 is close and both are within a reasonable range. Therefore, it is determined that the built-in mercury generator 2 is normal, while the analytical accuracy of the mercury analyzer 3 is abnormal. The measurement accuracy of the online mercury measurement system 100 is calibrated by calibrating the mercury analyzer 3. If, after analysis, it is found that the linear relative error of the online mercury measurement system 100 calculated in step S203 differs significantly from the linear relative error of the calibration mercury generator 4 calculated in step S204, but the linear relative error of the calibration mercury generator 4 is within a reasonable range, it indicates that the mercury analyzer 3 is normal, while the standard gas generation of the built-in mercury generator 2 is abnormal. The measurement accuracy of the online mercury measurement system 100 is calibrated by calibrating the built-in mercury generator 2.

[0089] In some embodiments, in step S203: if the linear relative error is determined to be greater than the maximum threshold of linear relative error, and the relative error of the dilution standard gas is determined to be within the normal range, then the focus is on checking for any abnormalities in the built-in elemental mercury generator 2 and the mercury analyzer 3. That is, to improve calibration accuracy, in step S203, after determining that the linear relative error is greater than the maximum threshold of linear relative error, it is simultaneously determined whether the relative error of the dilution standard gas is within the normal range. If it is determined that the relative error of the dilution standard gas is within the normal range, and any abnormalities in the dilution sampling component 1 are ruled out, then the calibration focus is placed on the built-in elemental mercury generator 2 and the mercury analyzer 3, thereby improving the accuracy and efficiency of the calibration.

[0090] To improve the accuracy of the calculation, in some specific embodiments, in step S201: n0 cycles are performed using mercury-free zero gas, where n0 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading is C0; in step S202: several standard gases are used to perform n3 cycles sequentially, where n3 is greater than 4, and the value of the last 4 cycles is taken as Hg. 0 Display C i， By removing non-steady-state data, the reliability and accuracy of the calculation results are improved.

[0091] Linear calibration method S2 specifically includes:

[0092] Step S200: Execute the sampling gun backflushing procedure until the backflushing is completed;

[0093] Step S201: Open the electromagnetic shut-off valve 5 to generate mercury-free zero gas using the built-in elemental mercury generator 2. The electromagnetic three-way valve 6 is located in channel A. The mercury-free zero gas is diluted by the dilution sampling component 1 according to the set dilution ratio and then sampled and measured throughout the entire process, executing n0 cycles (e.g., 4 cycles). The data from the first n0-2 cycles, marked as "zero gas unsteady state," are not included in the calculation; only the values ​​from the last 2 cycles are taken as Hg. 0 The reading C0 is used for calculations, and the data is noted as "Zero-valent mercury analysis dilution ratio calibration - zero gas";

[0094] Step S202: Keep the electromagnetic shut-off valve 5 open, and the built-in elemental mercury generator 2 sequentially presses the theoretical low concentration X1 (e.g., 2 μg / m³). 3 ), medium concentration X2 (e.g., 5 μg / m 3 ), high concentration X3 (e.g., 9 μg / m³) 3 A standard gas is generated and diluted according to the set dilution ratio using the dilution sampling component 1, based on the calibration gas volume. This diluted standard gas is then introduced into the mercury analyzer 3 for measurement. This process is repeated for n3 cycles (e.g., 6 cycles) to complete the linear calibration of three concentrations. For each concentration, the data in the first n3-4 cycles is marked as "standard gas unsteady state" and is not included in the calculation. Only the values ​​from the last 4 cycles are used for calculation, resulting in three sets of Hg values. 0 The readings, each group including multiple Hg values. 0 Display C i i = 1~3; Data notes status "Zero-valent mercury linear calibration - low / medium / high concentration standard gas";

[0095] Step S203: Calculate Hg 0 The result Y0 is calculated by multiplying the mean reading C0 by the dilution ratio, and the Hg for each group. 0 Display C i The calculated results Y1, Y2, and Y3 (mean × dilution ratio) are used to perform linear fitting on Y0, Y1, Y2, and Y3, calculating the slope k and intercept b. Based on the zero-point theoretical value X0, low concentration X1, medium concentration X2, and high concentration X3, the formula Z is applied. i =k*X i +b, calculate the regression value Z i i = 1 to 3, and according to formula D i =ABS(Z) i -X i ) / X i Calculate the linearity error D i Take D i The maximum value is Hg 0 If the linear relative error is greater than the maximum threshold for linear relative error, and the relative error of the diluted standard gas is within the normal range, then the focus should be on checking for any abnormalities in the built-in elemental mercury generator 2 and the mercury analyzer 3.

[0096] In some embodiments, the linear calibration method S2 includes the above step S204 to analyze and determine whether the malfunction is due to the mercury analyzer 3 or the built-in elemental mercury generator 2.

[0097] Furthermore, the linear calibration method S2 includes step S205: initiating mercury-free zero-gas purging, and closing the electromagnetic shut-off valve 5 after the purging is completed.

[0098] In some embodiments, a program can be written according to the above process to achieve automatic calibration of the online monitoring system for mercury emissions from stationary sources.

[0099] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 this invention and simplifying the description, and are not intended to 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 invention.

[0100] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0101] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0102] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0103] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0104] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for calibrating the accuracy of an online mercury measurement system, characterized in that, The online mercury element measurement system includes a dilution sampling component, a built-in mercury element generator, and a mercury analyzer. The method includes a dilution ratio self-calibration method S1: Step S101: The built-in elemental mercury generator produces mercury-free zero gas. This mercury-free zero gas is diluted by the dilution sampling component according to a set dilution ratio and then introduced into the mercury analyzer for measurement. Multiple cycles are performed to obtain multiple Hg values. 0 The reading is c0; Step S102: Set the calibration concentration and calibration gas volume. The built-in elemental mercury generator produces a standard gas with the calibration concentration. The standard gas is diluted according to the set dilution ratio using the dilution sampling component based on the calibration gas volume, and then introduced into the mercury analyzer for measurement. Multiple cycles are performed to obtain multiple Hg values. 0 The reading is c1; Step S103: Calculate the zero error according to the formula zero error = mean c0 × dilution ratio. If the zero error is greater than the maximum threshold of zero error, check the mercury analyzer to eliminate zero drift. Step S104: Calculate the relative error of the diluted standard gas according to the formula: relative error of diluted standard gas = (mean value of c1 × dilution ratio - calibration concentration) ÷ calibration concentration. If it is determined that the relative error of the diluted standard gas is greater than the maximum threshold of the relative error of the diluted standard gas, and the relative error of the direct standard gas is within the normal range, check the abnormality of the dilution sampling component. Checking the dilution sampling component includes checking whether there is gas path blockage and checking its temperature control module. Step S105: The standard gas from step S102 is directly introduced into the mercury analyzer according to the calibration gas volume for measurement, and multiple cycles are performed to obtain multiple Hg values. 0 The reading is c2; The relative error of the direct-through standard gas is calculated according to the formula: (mean of c2 - calibration concentration) ÷ calibration concentration. If the relative error of the direct-through standard gas is greater than the maximum threshold of the relative error of the direct-through standard gas, an external calibration elemental mercury generator is used to generate standard gas with a concentration of the calibration concentration. The standard gas is then directly passed to the mercury analyzer for measurement according to the calibration gas volume. The analysis determines whether the abnormality is due to the mercury analyzer or the internal elemental mercury generator. The theoretical dilution ratio is calculated according to the formula: theoretical dilution ratio = mean c2 ÷ mean c1. If the fluctuation value of the theoretical dilution ratio is greater than the fluctuation threshold, the dilution sampling component is determined to be abnormal.

2. The method for calibrating the accuracy of an online mercury measurement system according to claim 1, characterized in that, In step S101: n0 cycles are performed using the mercury-free zero gas, where n0 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading is c0; In step S102: the standard gas is used to perform n1 cycles, where n1 is greater than 4, and the value of the last 4 cycles is taken as Hg. 0 The reading is c1; Step S103: Perform n2 cycles using the standard gas, where n2 is greater than 2, and take the value of the last 2 cycles as Hg. 0 The reading is c2.

3. The method for calibrating the accuracy of an online mercury measurement system according to claim 1, characterized in that, It also includes linear calibration method S2: Step S201: The built-in elemental mercury generator produces mercury-free zero gas. This mercury-free zero gas is diluted by the dilution sampling component according to a set dilution ratio and then introduced into the mercury analyzer for measurement. Multiple cycles are executed to obtain multiple Hg values. 0 The reading is C0; Step S202: Select n calibration concentrations within the range of the mercury analyzer, where n≥3. The built-in elemental mercury generator sequentially generates standard gas according to the calibration concentrations. The generated standard gas is then diluted according to the set dilution ratio using the dilution sampling component based on the calibration gas volume, and then introduced into the mercury analyzer for measurement. This process is repeated multiple times to obtain multiple sets of Hg values. 0 The readings, each group including multiple Hg values. 0 Display C i , i = 1 ~ n; Step S203: Calculate Hg 0 The result Y0 is calculated by multiplying the mean reading C0 by the dilution ratio, and the Hg for each group. 0 Display C i The result of calculating Y: mean × dilution ratio i , Y0 and Y i Perform linear fitting, calculate the slope k and intercept b, and base the results on the theoretical value X0 at the zero point and the theoretical values ​​X at several calibration concentrations. i According to formula Z i =k X i +b, calculate the regression value Z i And according to formula D i =ABS(Z i -X i ) / X i Calculate the linearity error D i Take D i The maximum value is Hg 0 Linear relative error; If the linear relative error is greater than the maximum threshold of the linear relative error, check for abnormalities in the built-in elemental mercury generator and the mercury analyzer.

4. The method for calibrating the accuracy of an online mercury measurement system according to claim 3, characterized in that, The linear calibration method S2 also includes step S204: using an external calibration elemental mercury generator to sequentially generate standard gas of the same concentration as in step S202, and diluting the generated standard gas according to the set dilution ratio based on the calibration gas volume, and then passing it into a mercury analyzer for measurement, and analyzing and determining whether the abnormality is due to the mercury analyzer or the built-in elemental mercury generator.

5. The method for calibrating the accuracy of an online mercury measurement system according to claim 3, characterized in that, In step S203: If the linear relative error is determined to be greater than the maximum threshold of linear relative error, and the relative error of the diluted standard gas is determined to be within the normal range, check for any abnormalities in the built-in elemental mercury generator and the mercury analyzer.

6. The method for calibrating the accuracy of an online mercury measurement system according to claim 3, characterized in that, In step S201: n0 cycles are performed using the mercury-free zero gas, where n0 is greater than 2, and the value of the last 2 cycles is taken as Hg. 0 The reading is C0; In step S202: several standard gases are used to perform n3 cycles sequentially, where n3 is greater than 4, and the value of the last 4 cycles is taken as Hg. 0 Display C i .

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