Elemental Mercury and Mercuric Ion Monitoring System and Monitoring Method Based on Chemical Absorption

Abstract

An elemental mercury and divalent mercury monitoring system and monitoring method based on chemical absorption. The prior art uses a high-temperature conversion furnace, and the large temperature rise and fall make the system have poor sealing performance. The high-temperature pipelines and equipment are prone to air leakage, resulting in large deviations in mercury monitoring results. The composition of the present invention includes: a Venturi (1), which is connected to a heater A (5), a primary filter (2), a backflush valve B (4), and a secondary filter (6) through pipelines respectively. The secondary filter is connected to a critical orifice diluter (8) through a regulating valve (22). The critical orifice diluter is connected to a heater B (7), a three-way valve (11), and a reflux port (28) respectively. The three-way valve is connected to a total mercury reactor (12) and an elemental mercury reactor (13) respectively. Above the elemental mercury reactor, it is connected to a control valve A (23) and above the total mercury reactor respectively, and below it is connected to a waste liquid pump (14) and below the total mercury reactor. The present invention is used for an elemental mercury and divalent mercury monitoring system based on chemical absorption.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring, and particularly relates to a monitoring system and method for elemental mercury and divalent mercury based on chemical absorption. Background Art

[0002] Mercury is a highly toxic element. Elemental mercury can migrate globally, and the methyl mercury transformed during the migration process is more toxic, directly threatening human health. Mercury causes great damage to the human nervous system. A small amount of mercury can harm the brain and memory, and in severe cases, it can cause disability or even death. To protect human health and the environment from the hazards of anthropogenic emissions and releases of mercury and mercury compounds, China became one of the contracting parties to the Minamata Convention on Mercury in 2013;

[0003] Mercury in the atmosphere comes from natural processes and human activities. The mercury emission processes of natural sources mainly include: mercury emission from soil, water bodies, vegetation, volcanic activities, forest fires, and crust degassing into the atmosphere. Anthropogenic activities that emit mercury into the atmosphere include: coal combustion, waste incineration, chlor-alkali production, metal smelting and processing, etc. People are urgently in need of clarifying the emission laws of mercury from fixed pollution sources to provide reference for further controlling mercury emissions;

[0004] Existing fixed pollution source mercury sampling equipment generally uses a high-temperature conversion furnace to convert divalent mercury into elemental mercury for total mercury measurement. Elemental mercury can be directly measured, and the difference between total mercury and elemental mercury is divalent mercury. There are some deficiencies in the conversion of mercury forms by the sampling high-temperature conversion furnace;

[0005] Firstly, the sampling device is generally heated to 180 - 200 °C, and the temperature of the conversion furnace is above 750 °C. Mercury is easy to volatilize, and the system has high requirements for sealing. The large temperature rise and fall make the system sealing poor, and the high-temperature pipelines and equipment are prone to air leakage, resulting in system dilution ratio drift and large deviation in mercury monitoring results. Secondly, the high-temperature conversion system has high energy consumption. Taking an imported mercury monitoring device T3300 as an example, the heating power of the sampling device is 2.5 KW, and the power of the high-temperature furnace is 2.0 KW. In addition, long-term high-temperature operation has a fire hazard. Moreover, the heating, heating, and heat preservation structures of the high-temperature conversion furnace system are complex and large, with high failure rates and poor stability. Summary of the Invention

[0006] The purpose of the present invention is to provide a monitoring system and method for elemental mercury and divalent mercury based on chemical absorption. This structure and method can monitor the concentrations of elemental mercury and divalent mercury in real time, and has the advantages of no high-temperature heating, low system energy consumption, good sealing, and not easy to leak air at low temperatures, effectively improving the stability of the system.

[0007] The above purpose is achieved through the following technical solutions:

[0008] An elemental mercury and divalent mercury monitoring system based on chemical absorption, which comprises: a Venturi, the Venturi is connected to a heater A, a primary filter, a backflush valve B, and a secondary filter through pipelines respectively, the secondary filter is connected to a critical orifice diluter through a regulating valve, the critical orifice diluter is connected to a heater B, a three-way valve, and a return port respectively, the three-way valve is connected to a total mercury reactor and an elemental mercury reactor respectively, the upper part of the elemental mercury reactor is connected to a control valve A and the upper part of the total mercury reactor respectively, and its lower part is connected to a waste liquid pump and the lower part of the total mercury reactor respectively, the control valve A is connected to a divalent mercury absorption liquid tank through a delivery pump A.

[0009] In the elemental mercury and divalent mercury monitoring system based on chemical absorption, the upper part of the total mercury reactor is connected to a delivery pump B through a control valve B, the delivery pump B is connected to a divalent mercury conversion liquid tank, the total mercury reactor and the elemental mercury reactor are respectively connected to a standard flowmeter, the standard flowmeter is connected to a mercury analyzer, and the mercury analyzer is connected to a vacuum pump through a gaseous mercury adsorption tube.

[0010] In the elemental mercury and divalent mercury monitoring system based on chemical absorption, the waste liquid pump is connected to a drain valve, the heater A is connected to a gas sampling valve, the heater B is connected to a dilution gas valve, the primary filter is respectively connected to a backflush valve A and an intake valve, and the intake valve and the Venturi are respectively connected to a flue.

[0011] An elemental mercury and divalent mercury monitoring system and monitoring method based on chemical absorption, the method comprises the following steps:

[0012] Firstly, the inside of the Venturi is a trapezoidal orifice channel, the tip of the trapezoidal orifice points to the flue, the compressed air is adjusted to generate negative pressure in the pipeline behind the primary filter, and the flue gas sample enters the system under the action of siphonage. The critical orifice diluter collects the flue gas sample according to the dilution ratio Xn in the range of 1 / 100 - 1 / 10 by using the dilution gas, and the remaining sample gas returns to the fixed pollution source flue gas pipeline through the return port;

[0013] The total mercury reactor is filled with a 10% stannous chloride solution. The delivery pump B is a silica gel tube three-roller structure to ensure stable delivery of the 10% stannous chloride solution to the total mercury reactor. The control valve B on the pipeline can adjust and control the delivery flow rate. The stannous chloride solution can reduce the divalent mercury in the flue gas sample to elemental mercury and discharge it through the top of the total mercury reactor;

[0014] The elemental mercury reactor is filled with a 0.2mol / L potassium chloride solution. The delivery pump A is a silica gel tube three-roller structure to ensure stable delivery of the potassium chloride solution to the elemental mercury reactor. The control valve A on the pipeline can adjust and control the delivery flow rate. The potassium chloride solution can absorb the divalent mercury in the flue gas sample, and the flue gas sample after absorption is discharged through the top of the elemental mercury reactor;

[0015] The specific monitoring steps are as follows:

[0016] Step 1: Open the intake valve. After the backflush valve A purges the pipeline for 30 seconds, it closes. Then, open the backflush valve B to purge the primary filter, and then close the backflush valve B.

[0017] Step 2: Heater A heats the compressed air to 120°C. Open the gas sampling valve, and the flue gas sample flows through the primary filter under negative pressure.

[0018] Step 3: Open the regulating valve. Heater B heats the temperature to 120°C. Open the dilution gas valve to extract the mercury-free compressed air. Collect the flue gas sample through the outlet of the sampling critical orifice diluter at a dilution ratio Xn within the range of 1 / 100 - 1 / 10. The remaining sample gas returns to the fixed pollution source flue gas pipeline through the reflux port.

[0019] Step 4: Open the three-way valve to the total mercury reactor side for 60 seconds to measure the total mercury in the flue gas. After the total mercury test, open the three-way valve to the elemental mercury reactor side for 60 seconds. The three-way valve switches between measuring the total mercury and elemental mercury at 60-second intervals.

[0020] Step 5: The stannous chloride solution in the total mercury reactor reduces the divalent mercury in the flue gas sample to elemental mercury. The reaction is as follows:

[0021] Sn 2+ +Hg 2+ →Sn 4+ +Hg 0 ↑

[0022] The elemental mercury reduced from divalent mercury plus the elemental mercury originally in the flue gas sample is discharged from the top of the mercury reactor and enters the mercury analyzer to measure the total mercury content M Hg总 ;

[0023] Step 6: The potassium chloride solution in the elemental mercury reactor has the property of dissolving and absorbing divalent mercury while not dissolving elemental mercury. The divalent mercury in the flue gas sample is absorbed by the potassium chloride solution, and the unabsorbed elemental mercury is discharged from the top of the elemental mercury reactor and enters the mercury analyzer to measure the elemental mercury content M Hg0 ;

[0024] Step 7: The standard flowmeter feeds back the volume Vx of the flue gas sample detected in real time to the mercury analyzer at 60-second intervals. The elemental mercury concentration, divalent mercury concentration, and total mercury concentration are calculated according to the following formulas:

[0025] Elemental mercury concentration C(Hg 0 ) = Xn * M Hg0 / Vx;

[0026] Divalent mercury concentration C(Hg 2+) = Xn * (M Hg总 - M Hg0 ) / Vx;

[0027] The total mercury concentration C(Hg) = Xn * M Hg总 / Vx;

[0028] Step 8: According to the concentrations of the divalent mercury absorption solution and the divalent mercury conversion solution, combined with the concentrations of various forms of mercury in the flue gas sample, predict the failure times of the stannous chloride solution and the potassium chloride solution. When the time comes, turn on the waste liquid pump, transfer pump A, and transfer pump B to replace the effective solution.

[0029] Advantages:

[0030] 1. The present invention is an elemental mercury and divalent mercury monitoring system based on chemical absorption. This structure reduces divalent mercury in the flue gas sample to elemental mercury through a total mercury reactor for real-time monitoring of total mercury, and the elemental mercury reactor absorbs divalent mercury in the flue gas sample for real-time monitoring of elemental mercury. It can monitor the concentrations of elemental mercury and divalent mercury in real time, and has the advantages of no high-temperature heating, low system energy consumption, good system sealing, and not easy to leak at low temperatures, effectively improving the accuracy of mercury monitoring results and the stability of the system.

[0031] 2. The present invention has no high-temperature conversion furnace system, with a clever structure, low failure rate, and good reliability. It is suitable for fixed pollution source emissions in the temperature range of 50 - 180 °C, has a wide application scenario. At the same time, the large dilution ratio design of this structure has strong adaptability to the components of the flue gas sample.

[0032] 3. The present invention uses secondary filtration to remove particles in the flue gas, improving its adaptability to the flue gas. At the same time, it avoids the adsorption of particulate matter on gaseous divalent mercury, preventing the distortion of the states of different forms of mercury in the flue gas. It uses a stannous chloride reducing solution to reduce and convert divalent mercury in the flue gas into elemental mercury to monitor the total mercury concentration in the flue gas, and switches to a potassium chloride solution to adsorb divalent mercury in the flue gas to monitor the elemental mercury concentration in the flue gas, realizing the separate monitoring of elemental mercury and divalent mercury in the flue gas by form.

[0033] 4. The technical indicators of the fixed pollution source particulate mercury and gaseous mercury sampling device of the present invention meet the quality assurance and quality control requirements of the internationally advanced EPA Method 30A standard, improving the representativeness of different forms of mercury sampling from fixed sources, and having the advantages of wide application range, low energy consumption, simple operation, and high accuracy. Description of the Drawings

[0034] Attached Figure 1 is the structural schematic diagram of the present invention.

[0035] Among them: 1. Venturi, 2. Primary filter, 3. Backwash valve A, 4. Backwash valve B, 5. Heater A, 6. Secondary filter, 7. Heater B, 8. Critical orifice diluter, 9. Divalent mercury absorption liquid tank, 10. Delivery pump A, 11. Three-way valve, 12. Total mercury reactor, 13. Elemental mercury reactor, 14. Waste liquid pump, 15. Delivery pump B, 16. Divalent mercury conversion liquid tank, 17. Mercury analyzer, 18. Gaseous mercury adsorption tube, 19. Vacuum pump, 20. Gas sampling valve, 21. Dilution gas valve, 22. Control valve, 23. Control valve A, 24. Control valve B, 25. Standard flowmeter, 26. Drain valve, 27. Inlet valve, 28. Return port. Detailed implementation mode

[0036] Example 1:

[0037] An elemental mercury and divalent mercury monitoring system based on chemical absorption, which comprises: a Venturi 1, the Venturi is respectively connected to a heater A 5, a primary filter 2, a backwash valve B 4, and a secondary filter 6 through pipelines, the secondary filter is connected to a critical orifice diluter 8 through a control valve 22, the critical orifice diluter is respectively connected to a heater B 7, a three-way valve 11, and a return port 28, the three-way valve is respectively connected to a total mercury reactor 12 and an elemental mercury reactor 13, the upper part of the elemental mercury reactor is respectively connected to a control valve A 23 and the upper part of the total mercury reactor, and its lower part is connected to a waste liquid pump 14 and the lower part of the total mercury reactor, and the control valve A is connected to a divalent mercury absorption liquid tank 9 through a delivery pump A 10.

[0038] Example 2:

[0039] For the elemental mercury and divalent mercury monitoring system based on chemical absorption according to Example 1, the upper part of the total mercury reactor is connected to a delivery pump B 15 through a control valve B 24, the delivery pump B is connected to a divalent mercury conversion liquid tank 16, the total mercury reactor and the elemental mercury reactor are respectively connected to a standard flowmeter 25, the standard flowmeter is connected to a mercury analyzer 17, and the mercury analyzer is connected to a vacuum pump 19 through a gaseous mercury adsorption tube 18.

[0040] Example 3:

[0041] For the elemental mercury and divalent mercury monitoring system based on chemical absorption according to Example 2, the waste liquid pump is connected to a drain valve, the heater A is connected to a gas sampling valve 20, the heater B is connected to a dilution gas valve 21, the primary filter is respectively connected to a backwash valve A 3 and an inlet valve 27, and the inlet valve and the Venturi are respectively connected to a flue.

[0042] Example 4:

[0043] The elemental mercury and divalent mercury monitoring system based on chemical absorption according to Embodiment 2, wherein the material of the primary filter is a porous ceramic body with a hollow interior, which is used to filter out large particles above 1 µm. The backflush valves A and B are connected to compressed air with a pressure greater than 100 kPa. The backflush valve A is used to purge the intake pipeline and the intake valve, and the backflush valve B is used to backflush the primary filter to avoid blockage by fly ash. The heater A is equipped with a nickel-chromium electrothermal alloy heating wire, which is used to heat the sampling motive gas entering the Venturi. The secondary filter is a porous ceramic filter with many micropores, which is used to filter out particles above 0.3 µm. The heater B is equipped with a nickel-chromium electrothermal alloy to heat the dilution gas entering the critical orifice diluter. The critical orifice diluter uses the dilution gas to sample the flue gas sample at a dilution ratio of 1 / 100 - 1 / 10, and the remaining flue gas sample returns to the flue through the reflux port;

[0044] The divalent mercury absorption solution contains a 0.2 mol / L potassium chloride solution, which is prepared from superior-grade pure reagents and deionized water with a conductivity of 0.055 μS / cm. The transfer pump A is a silica gel tube three-roller structure to ensure stable delivery of the potassium chloride solution to the elemental mercury reactor. The control valve A on the pipeline can adjust and control the delivery flow rate. The three-way valve sends the diluted flue gas sample to the total mercury reactor and the elemental mercury reactor at different times, with a sampling interval of 60 seconds. The total mercury reactor contains a 10% stannous chloride solution, and the stannous chloride solution can reduce divalent mercury in the flue gas sample to elemental mercury, which is discharged from the top of the total mercury reactor. The elemental mercury reactor contains a 0.2 mol / L potassium chloride solution, and the potassium chloride solution can absorb divalent mercury in the flue gas sample. After absorption, the flue gas sample is discharged from the top of the elemental mercury reactor;

[0045] The waste liquid pump periodically discharges the waste liquid from the total mercury reactor and the elemental mercury reactor. The divalent mercury conversion solution contains a 10% stannous chloride solution, which is prepared by diluting a 20% stannous chloride solution with deionized water with a conductivity of 0.055 μS / cm, and is input into the total mercury reactor through the transfer pump B and the control valve B;

[0046] The transfer pump B is a silica gel tube three-roller structure to ensure stable delivery of the 10% stannous chloride solution to the total mercury reactor. The control valve B on the pipeline can adjust and control the delivery flow rate;

[0047] The mercury analyzer is an ultraviolet atomic absorption mercury spectrometer, which detects the mercury content according to the absorbance at a wavelength of 253.7 nm. After detection, the exhaust gas enters the gaseous mercury adsorption tube;

[0048] The gaseous mercury adsorption tube contains modified activated carbon, which adsorbs mercury in the flue gas sample to prevent mercury from being discharged into the atmosphere. The vacuum pump provides the driving force for transporting the flue gas sample;

[0049] The described standard flowmeter includes a photoelectric detector, a diaphragm flowmeter, and a thermocouple, and is used to measure the standard state volume (273.15K, 101.325kPa) of the flue gas sample in real time for calculating the mercury concentrations in different forms.

[0050] Example 5:

[0051] According to the monitoring method of the elemental mercury and divalent mercury monitoring system based on chemical absorption described in Examples 1-4, the method includes the following steps:

[0052] Firstly, the inside of the Venturi is a trapezoidal orifice channel, with the tip of the trapezoidal orifice pointing to the flue. Adjust the compressed air to create a negative pressure in the pipeline after the primary filter. The flue gas sample enters the system under the action of siphon. The critical orifice diluter uses the dilution gas to collect the flue gas sample at a dilution ratio Xn within the range of 1 / 100 - 1 / 10, and the remaining sample gas returns to the fixed pollution source flue gas pipeline through the reflux port;

[0053] The total mercury reactor is filled with a 10% stannous chloride solution. The delivery pump B is a three-roller structure of silica gel tube to ensure stable delivery of the 10% stannous chloride solution to the total mercury reactor. The control valve B on the pipeline can adjust and control the delivery flow rate. The stannous chloride solution can reduce the divalent mercury in the flue gas sample to elemental mercury and discharge it through the top of the total mercury reactor;

[0054] The elemental mercury reactor is filled with a 0.2mol / L potassium chloride solution. The delivery pump A is a three-roller structure of silica gel tube to ensure stable delivery of the potassium chloride solution to the elemental mercury reactor. The control valve A on the pipeline can adjust and control the delivery flow rate. The potassium chloride solution can absorb the divalent mercury in the flue gas sample, and the flue gas sample after absorption is discharged through the top of the elemental mercury reactor;

[0055] The specific monitoring steps are as follows:

[0056] Step 1: Open the intake valve. After the backflush valve A purges the pipeline for 30 seconds, it is closed. Open the backflush valve B to purge the primary filter, and then close the backflush valve B;

[0057] Step 2: Heater A heats the compressed air to 120°C, open the gas sampling valve, and the flue gas sample flows through the primary filter under the action of negative pressure;

[0058] Step 3: Open the regulating valve. Heater B heats the temperature to 120°C, open the dilution gas valve to extract the clean mercury compressed air, and collect the flue gas sample at a dilution ratio Xn within the range of 1 / 100 - 1 / 10 through the outlet of the sampling critical orifice diluter. The remaining sample gas returns to the fixed pollution source flue gas pipeline through the reflux port;

[0059] Step 4: Open the three-way valve to the total mercury reactor side for 60 seconds to measure the total mercury in the flue gas. After the total mercury test is completed, open the three-way valve to the elemental mercury reactor side for 60 seconds. The three-way valve switches between measuring total mercury and elemental mercury at 60-second intervals;

[0060] Step 5: The stannous chloride solution in the total mercury reactor reduces divalent mercury in the flue gas sample to elemental mercury. The reaction is as follows:

[0061] Sn 2+ +Hg 2+ →Sn 4+ +Hg 0 ↑

[0062] The elemental mercury reduced from divalent mercury and the elemental mercury originally in the flue gas sample are discharged together from the top of the mercury reactor and enter the mercury analyzer to measure the total mercury content M Hg总 ;

[0063] Step 6: The potassium chloride solution in the elemental mercury reactor has the characteristics of dissolving and absorbing divalent mercury while not dissolving elemental mercury. Divalent mercury in the flue gas sample is absorbed by the potassium chloride solution, and the unabsorbed elemental mercury is discharged from the top of the elemental mercury reactor and enters the mercury analyzer to measure the elemental mercury content M Hg0 ;

[0064] Step 7: The standard flowmeter feeds back the volume Vx of the flue gas sample detected in real time to the mercury analyzer at 60-second intervals. The elemental mercury concentration, divalent mercury concentration, and total mercury concentration are calculated as follows:

[0065] Elemental mercury concentration C(Hg 0 ) = Xn*M Hg0 / Vx;

[0066] Divalent mercury concentration C(Hg 2+ ) = Xn*(M Hg总 - M Hg0 ) / Vx;

[0067] Total mercury concentration C(Hg) = Xn*M Hg总 / Vx;

[0068] Step 8: Based on the concentrations of the divalent mercury absorption solution and the divalent mercury conversion solution, combined with the concentrations of various forms of mercury in the flue gas sample, predict the failure times of the stannous chloride solution and the potassium chloride solution. When the time comes, turn on the waste liquid pump, transfer pump A, and transfer pump B to replace the effective solution.

Claims

1. An elemental mercury and divalent mercury monitoring system based on chemical absorption, which comprises: Venturi, characterized in that: the Venturi is respectively connected to a heater A, a primary filter, a backflush valve B, and a secondary filter through pipelines; the secondary filter is connected to a critical orifice diluter through a regulating valve; the critical orifice diluter is respectively connected to a heater B, a three-way valve, and a return port; the three-way valve is respectively connected to a total mercury reactor and an elemental mercury reactor; above the elemental mercury reactor is respectively connected to a control valve A and above the total mercury reactor, and below it is connected to a waste liquid pump and below the total mercury reactor; the control valve A is connected to a divalent mercury absorption liquid tank through a delivery pump A; specifically, the total mercury reactor reduces divalent mercury in the flue gas sample to elemental mercury for real-time total mercury monitoring, and the elemental mercury reactor absorbs divalent mercury in the flue gas sample for real-time elemental mercury monitoring, monitors the concentrations of elemental mercury and divalent mercury in real time, removes particles in the flue gas by secondary filtration, reduces divalent mercury in the flue gas to elemental mercury with a stannous chloride reducing solution, monitors the total mercury concentration in the flue gas, switches to a potassium chloride solution to adsorb divalent mercury in the flue gas, and monitors the elemental mercury concentration in the flue gas, so as to realize the morphological monitoring of elemental mercury and divalent mercury in the flue gas.

2. The elemental mercury and divalent mercury monitoring system based on chemical absorption according to claim 1, characterized in that: Above the total mercury reactor is connected to a delivery pump B through a control valve B; the delivery pump B is connected to a divalent mercury conversion liquid tank; the total mercury reactor and the elemental mercury reactor are respectively connected to a standard flowmeter; the standard flowmeter is connected to a mercury analyzer; the mercury analyzer is connected to a vacuum pump through a gaseous mercury adsorption tube.

3. The elemental mercury and divalent mercury monitoring system based on chemical absorption according to claim 1, wherein: The waste liquid pump is connected to a drain valve; the heater A is connected to a gas sampling valve; the heater B is connected to a dilution gas valve; the primary filter is respectively connected to a backflush valve A and an intake valve; the intake valve and the Venturi are respectively connected to a flue.

4. The mercury element and divalent mercury monitoring system and monitoring method based on chemical absorption according to any one of claims 1 to 3, characterized in that: This method includes the following steps: Firstly, the inside of the Venturi is a trapezoidal orifice channel, with the tip of the trapezoidal orifice pointing to the flue. Adjust the compressed air to generate negative pressure in the pipeline behind the primary filter, and the flue gas sample enters the system under the action of siphon. The critical orifice diluter collects the flue gas sample at a dilution ratio Xn within the range of 1 / 100 - 1 / 10 using dilution gas, and the remaining sample gas returns to the fixed pollution source flue gas pipeline through the return port. The total mercury reactor is filled with a 10% stannous chloride solution. The delivery pump B is a silica gel tube three-roller structure to ensure stable delivery of the 10% stannous chloride solution to the total mercury reactor. The control valve B on the pipeline can regulate and control the delivery flow rate. The stannous chloride solution can reduce divalent mercury in the flue gas sample to elemental mercury and discharge it through the top of the total mercury reactor. The elemental mercury reactor is filled with a 0.2 mol / L potassium chloride solution. The delivery pump A is a silica gel tube three-roller structure to ensure stable delivery of the potassium chloride solution to the elemental mercury reactor. The control valve A on the pipeline can regulate and control the delivery flow rate. The potassium chloride solution can absorb divalent mercury in the flue gas sample, and the flue gas sample after absorption is discharged through the top of the elemental mercury reactor. The specific monitoring steps are as follows: Step 1: Open the intake valve, close the backflush valve A after purging the pipeline for 30 seconds, open the backflush valve B to purge the primary filter, and then close the backflush valve B. Step 2: Heater A heats the compressed air to 120 °C, opens the gas sampling valve, and the flue gas sample flows through the primary filter under negative pressure. Step 3: The regulating valve is opened, Heater B heats the temperature to 120 °C, the dilution gas valve is opened to extract the purified mercury compressed air, and the flue gas sample is collected at a dilution ratio Xn in the range of 1 / 100 - 1 / 10 through the outlet of the sampling critical orifice diluter. The remaining sample gas returns to the fixed pollution source flue gas pipeline through the reflux port. Step 4: The three-way valve is opened to the total mercury reactor side for 60 seconds to measure the total mercury in the flue gas. After the total mercury test is completed, the three-way valve is opened to the elemental mercury reactor side for 60 seconds. The three-way valve switches between the measurement of total mercury and the measurement of elemental mercury at 60-second intervals. Step 5: The stannous chloride solution in the total mercury reactor reduces the divalent mercury in the flue gas sample to elemental mercury, and the reaction is as follows: Sn 2+ + Hg 2+ → Sn 4+ + Hg 0 ↑ The elemental mercury reduced from divalent mercury, together with the elemental mercury originally present in the flue gas sample, is discharged from the top of the mercury reactor and enters the mercury analyzer to measure the total mercury content M Hg总 ; Step 6: The potassium chloride solution in the elemental mercury reactor has the characteristics of dissolving and absorbing divalent mercury while not dissolving elemental mercury. Divalent mercury in the flue gas sample is absorbed by the potassium chloride solution, and the unabsorbed elemental mercury is discharged from the top of the elemental mercury reactor and enters the mercury analyzer to measure the elemental mercury content M Hg0 ; Step 7: The standard flowmeter feeds back the volume Vx of the flue gas sample detected in real time to the mercury analyzer at 60-second intervals. The elemental mercury concentration, divalent mercury concentration, and total mercury concentration are calculated according to the following formula: Elemental mercury concentration C(Hg 0 ) = Xn * M Hg0 / Vx; Divalent mercury concentration C(Hg 2+ ) = Xn * (M Hg总 - M Hg0 ) / Vx; Total mercury concentration C(Hg) = Xn * M Hg总 / Vx; Step 8: According to the concentrations of the divalent mercury absorption solution and the divalent mercury conversion solution, combined with the mercury concentrations in various forms of the flue gas sample, predict the failure time of the stannous chloride solution and the potassium chloride solution. When the time comes, turn on the waste liquid pump, transfer pump A, and transfer pump B to replace the effective solution.

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