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Stationary source emission - Determination of carbon monoxide - Fixed potential by electrolysis method
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HJ 973-2018
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| Standard ID | HJ 973-2018 (HJ973-2018) | | Description (Translated English) | Stationary source emission - Determination of carbon monoxide - Fixed potential by electrolysis method | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z25 | | Word Count Estimation | 9,910 |
HJ 973-2018
Stationary source emission - Determination of carbon monoxide - Fixed potential by electrolysis method
National Environmental Protection Standard of the People's Republic
Determination of carbon monoxide in fixed pollution source
Constant potential electrolysis
Stationary source emission - Determination of carbon monoxide
- Fixed potential by electrolysis method
Published on.2018-11-13
2019-03-01 Implementation
Ministry of Ecology and Environment released
i directory
Foreword.ii
1 Scope..1
2 Normative references..1
3 Terms and Definitions.1
4 principle of the method..2
5 interference and elimination. 2
6 reagents and materials. 2
7 instruments and equipment.2
8 Sampling and measurement.3
9 result calculation and representation..4
10 Precision and Accuracy 4
11 Quality Assurance and Quality Control.5
12 Notes 5
Appendix A (informative appendix) instrument performance review results before and after testing..6
Foreword
To protect the "Environmental Protection Law of the People's Republic of China" and the "Air Pollution Control Law of the People's Republic of China"
This standard is formulated to ensure the health of human body and to regulate the determination of carbon monoxide in waste gas from fixed sources.
This standard specifies a potentiometric electrolysis method for the determination of carbon monoxide in a fixed source of exhaust gas.
The concentration in this standard refers to the mass concentration or volume fraction.
Appendix A of this standard is an informative annex.
This standard is the first release.
This standard is formulated by the Department of Eco-Environmental Monitoring, the Department of Regulation and Standards of the Ministry of Ecology and Environment.
This standard was drafted. Shandong Environmental Monitoring Center Station, Shandong University.
This standard is verified by. Tianjin Ecological Environment Monitoring Center, Hebei Environmental Monitoring Center, and Nanjing Environmental Monitoring
Xinzhan, Jinan Environmental Monitoring Center Station, Liaocheng Environmental Monitoring Center, Zouping County Environmental Monitoring Station.
This standard is approved by the Ministry of Ecology and Environment on November 13,.2018.
This standard has been implemented since March 1,.2019.
This standard is explained by the Ministry of Ecology and Environment.
1 Determination of carbon monoxide in fixed source pollution - Determination of potentiometric electrolysis
1 Scope of application
This standard specifies a potentiometric electrolysis method for the determination of carbon monoxide in a fixed source of exhaust gas.
This standard applies to the determination of carbon monoxide in fixed source pollution.
The detection limit of this standard is 3 mg/m3, and the lower limit of determination is 12 mg/m3.
2 Normative references
This standard refers to the following documents or their terms. For undated references, the valid version applies to this
standard.
GB/T 16157 Determination of particulate matter in fixed pollution source exhaust gas and sampling method of gaseous pollutants
HJ/T 373 Technical Specifications for Quality Assurance and Quality Control of Fixed Pollution Source Monitoring (Trial)
HJ/T 397 Fixed Source Exhaust Gas Monitoring Technical Specification
3 Terms and definitions
The following terms and definitions apply to this standard.
3.1
Zero gas
There is no measurement component or less than the specified value, other component concentration does not interfere with the measurement component result or the resulting measurement component is dry
Disturbing negligible gases.
3.2
Calibration span
The upper limit of the calibration of the instrument is the concentration value of the standard gas used for calibration. (For multi-point calibration, the standard gas used for calibration)
The highest mass concentration value of the body), the calibration range (indicated by CS below) should be less than or equal to the full scale of the instrument.
3.3
Calibration error
The standard gas is directly introduced into the error between the analyzer's measurement and the standard gas concentration.
3.4
System bias
The difference between the direct introduction of the standard gas into the analyzer and the measurement result of the sample tube into the analyzer, which is the calibration range
percentage.
3.5
Zero drift
Before and after the test, the difference between the analyzer and the same zero gas measurement is the percentage of the calibration range.
23.6
Range drift
Before and after the test, the difference between the analyzer's measurement results for the same concentration of standard gas, as a percentage of the calibration range.
4 Principle of the method
The sample is taken into a pass consisting mainly of an electrolytic cell, an electrolyte and an electrode (sensitive electrode, reference electrode and counter electrode)
Sensor. Carbon monoxide diffuses through the permeable membrane to the surface of the sensitive electrode, and an oxidation reaction occurs on the sensitive electrode.
eHCOOHCO 242 232
This results in a limit diffusion current (i). Under the specified working conditions, the number of electron transfer (Z), Faraday constant (F),
The gas diffusion area (S), the diffusion coefficient (D), and the thickness of the diffusion layer () are constant, and the limit is expanded within a certain range.
The magnitude of the scattered current (i) is proportional to the concentration of carbon monoxide (c), so the oxygen can be determined from the ultimate diffusion current (i).
Carbon concentration (c).
DSFZ
i (1)
5 interference and elimination
5.1 Particles, moisture, etc. in the gas to be tested are likely to condense on the surface of the sensor permeable membrane and cause damage to the sensor, affecting one
Determination of carbon oxide; filtration should be carried out using a dust filter device or a dehumidification device to eliminate the influence.
5.2 Hydrogen has a significant interference with the determination of carbon monoxide. The carbon monoxide sensor installed in the analyzer should have anti-hydrogen interference function.
5.3 Acid gas interferes with the determination of the sample. The analyzer should be filtered with a built-in chemical filter to eliminate the effect.
5.4 Ethylene interferes with the determination of the sample. When determining the sample gas containing ethylene concentration exceeding 100 μmol/mol, it should be used with caution.
This standard.
6 reagents and materials
6.1 Carbon monoxide standard gas
Commercially available certified standard gas, uncertainty ≤ 2%.
6.2 Zero gas
Nitrogen with a purity of ≥99.99% or clean air that does not interfere with the measurement.
7 Instruments and equipment
7.1 Constant potential electrolysis carbon monoxide analyzer
37.1.1 Composition
Constant potential electrolysis carbon monoxide analyzer (abbreviation. analyzer or instrument) consists of. analyzer (including gas flow meter and
Control unit, pump, sensor, etc.), sampling tube (including dust filter, etc.), air duct, dehumidifier, portable
Printing machine, etc.
7.1.2 Performance requirements
a) indication error. no more than ± 5% (standard gas concentration value < 100 μmol/mol, no more than ± 5 μmol/mol);
b) system deviation. no more than ± 5%;
c) zero drift. no more than ± 3% (no more than ± 5% when the calibration range is ≤.200 μmol/mol);
d) Range drift. no more than ± 3% (no more than ± 5% when the calibration range is ≤.200 μmol/mol);
e) With sampling flow display function.
7.2 Standard gas cylinder
With adjustable pressure reducing valve, adjustable rotor flow meter and air guiding tube.
7.3 gas bag
Used to calibrate the analyzer by air bag method. The volume is not less than 4 L, and the lining material should be made of aluminum plastic complex with little influence on the measured components.
Inert materials such as film and polytetrafluoroethylene film.
8 sampling and determination
8.1 Determination of sampling points and sampling frequency
According to GB/T 16157, HJ/T 373 and HJ/T 397 and relevant regulations, the sampling position, sampling point and frequency are determined.
8.2 Tester air tightness check
According to the instruction manual of the instrument, connect the analyzer, sampling tube, air tube, etc. correctly, and then press the working condition of the instrument.
GB/T 16157 checks for air tightness. If the inspection is unqualified, it should be checked and maintained until the inspection is qualified.
8.3 Analyzer calibration
8.3.1 Zero calibration
Introduce zero gas into the analyzer and calibrate the instrument zero point.
8.3.2 Range calibration
Estimate the gas concentration to be measured and set the calibration range. The carbon monoxide standard gas (6.1) is passed to the analyzer for measurement.
The indication error shall comply with the requirements of 7.1.2 a), otherwise calibration is required. The calibration method is as follows.
a) Air bag method. fill the clean gas bag with standard gas (6.1) and then empty it, repeat it three times, then fill it up and use it.
Calibrate according to the calibration procedure specified in the instrument's instruction manual.
4b) Cylinder method. connect the standard gas (6.1) cylinder to the measuring tube sampling tube, open the cylinder gas valve, adjust the decompression
The valve and the rotameter are used to introduce a standard gas into the meter at a flow rate specified by the analyzer. According to the instructions in the instrument manual
The calibration steps are calibrated.
8.4 Sample determination
8.4.1 Place the front end of the analyzer sampling tube on the sampling point in the exhaust cylinder, and block the sampling hole so that it does not leak.
8.4.2 Start the air pump and take the sample flow measurement according to the meter's specified sampling flow. After the meter is stable, save the test by the minute.
The data was measured and the average value of the measured data was taken continuously for 5 minutes to 15 minutes as a single measurement value.
8.4.3 After the end of one measurement, clean the instrument with zero gas (6.2) as specified in the instrument manual.
8.4.4 After the test is finished, clean the analyzer with zero gas (6.2); after the value returns to near zero, turn off the power and shut down.
Beam measurement.
9 Calculation and representation of results
9.1 Calculation of results
The concentration of carbon monoxide should be expressed as the mass concentration in the dry flue gas under standard conditions.
If the instrument indication is expressed in volume fraction, it should be converted as follows.
ρ=1.25x (2)
Where. ρ--the mass concentration of carbon monoxide in the dry flue gas under standard conditions, mg/m3;
X--the volume fraction of carbon monoxide in the gas to be measured, μmol/mol;
1.25--the ratio of the carbon monoxide volume ratio concentration to the mass concentration in the flue gas under standard conditions, g/L.
9.2 Results representation
Carbon monoxide concentration results should be kept in integers, with up to three significant digits.
10 Precision and accuracy
10.1 Precision
6 validation laboratories for carbon monoxide standard gases at concentrations of 50 mg/m3, 125 mg/m3 and 378 mg/m3
Make the measurement.
The relative standard deviations in the experimental room are. 0% to 2.6%, 0.5% to 2.2%, and 0.2% to 0.6%;
The relative standard deviations between laboratories were. 1.5%, 1.5%, and 1.3%, respectively;
The repeatability limits were. 2 mg/m3, 4 mg/m3 and 4 mg/m3, respectively;
Reproducibility limits were. 3 mg/m3, 6 mg/m3, and 14 mg/m3, respectively.
6 verification laboratories discharge coal-fired boilers of a power plant, incinerators of a domestic waste incineration plant, and rotary kiln of a cement plant
The concentration of carbon monoxide in the flue gas was measured simultaneously. The concentration of carbon monoxide in the flue gas of coal-fired boilers is 11 mg/m3 to 15 mg/m3.
The average value is 13 mg/m3; the concentration of carbon monoxide in the flue gas of the incinerator is 86 mg/m3 to 109 mg/m3, with an average value of 96 mg/m3;
The concentration of carbon monoxide in the flue gas of the rotary kiln is 264 mg/m3 to 329 mg/m3, with an average value of 298 mg/m3.
The relative standard deviations in the experimental room were. 4.4% to 11.5%, 4.5% to 7.7%, and 2.2% to 3.9%;
The relative standard deviations between laboratories were. 7.2%, 1.7%, and 6.1%, respectively;
The repeatability limits were. 3 mg/m3, 16 mg/m3 and 24 mg/m3;
Reproducibility limits were. 4 mg/m3, 16 mg/m3 and 55 mg/m3, respectively.
10.2 Accuracy
6 validation laboratories for carbon monoxide standard gases at concentrations of 50 mg/m3, 125 mg/m3 and 378 mg/m3
Make the measurement.
The relative errors are. -4.7% to -0.5%, -2.5% to 1.5%, and -1.5% to 2.2%;
The relative error final values were. -2.5% ± 3.0%, -0.3% ± 3.0%, and 0.8% ± 2.6%, respectively.
11 Quality Assurance and Quality Control
11.1 Before monitoring, measure zero gas (6.2) and carbon monoxide standard gas (6.1), calculate indication error, system deviation,
Appendix A is recorded in the form of a table. If the indication error and/or system deviation does not meet the requirements of 7.1.2 a) and b),
Find the cause and perform instrument maintenance or repair until the requirements are met.
11.2 After monitoring, zero gas (6.2) and carbon monoxide standard gas (6.1) are measured again to calculate the indication error and system deviation.
Record in the form of an Appendix A form. If the indication error and system deviation meet the requirements of 7.1.2 a) and b), determine
The sample measurement result is valid; otherwise, the determination result of the sample is invalid.
Note. Before and after the test, the whole system indication error including sampling tube, air tube and dehumidifier can be used instead of the analyzer error and system.
The inspection of the system deviation [its evaluation of the implementation of 7.1.2 a)].
11.3 The sample measurement result should be between 20% and 100% of the calibration range of the instrument, otherwise the calibration range should be re-selected;
If the sample measurement result is not greater than the lower measurement limit, there is no need to reselect the calibration range.
11.4 At least one zero drift and span drift check shall be performed every quarter and recorded in the form of Appendix A. If
Zero drift and range drift do not meet the requirements of 7.1.2 c) and d), and the instrument should be maintained or repaired in time.
11.5 The service life of the constant potential electrolysis sensor is generally not more than 2 years, and should be replaced in time after expiration. When calibrating the sensor,
If the dynamic range is found to be small, the upper limit of measurement does not reach the full scale value, or the value of the indication error is exceeded when the calibration range of the instrument is rechecked.
The requirements of 7.1.2 a) indicate that the sensor has failed and should be replaced in time.
12 Precautions
12.1 The analyzer shall be operated under the conditions of its specified ambient temperature, ambient humidity, etc.
12.2 The temperature of the exhaust gas entering the constant potential electrolysis sensor should not exceed 40 °C.
12.3 The analyzer shall have anti-negative pressure capability to ensure that the sampling flow rate is not lower than its specified flow range.
12.4 The measuring instrument should be equipped with a rechargeable battery, which can automatically display the remaining power, and should ensure sufficient power during use;
When the instrument is not used for a long time, it should be powered on at least once a month to maintain the polarization of the sensor.
12.5 The analyzer dust filter should be cleaned in time to prevent blockage of the air circuit.
12.6 When measuring simultaneously with other target contaminants, use a heated sampling tube as needed.
6 Appendix A
(informative appendix)
Instrument performance review results before and after testing
Laboratory name test location
Instrument manufacturer model number, numbering principle
Instrument range (μmol/mol, mg/m3) gas flow rate (L/min)
Ambient temperature (°C) Ambient pressure/kPa Relative humidity (RH%)
Standard gas production unit pollutant name and effective deadline
Tester measurement date year, month and day
Table A.1 indication error
Standard gas test before testing
Name concentration A measured value iA average value iA
Indication error
( iA -A)/A
Measured value iA average value iA
Indication error
( iA -A)/A
CO
Note. The measured value Ai refers to the measurement result of the standard gas directly introduced into the analyzer.
Schedule A.2 System deviation
Standard gas test before testing
name
concentration
measured value
System deviation
(B - A )/CS
measured value
System deviation
( B - A )/CSA ABBAABB
Zero gas
CO
Note. 1. The measured value A refers to the measurement result of the standard gas directly introduced into the analyzer;
2. The measured value B refers to the measurement result of the standard gas introduced into the analyzer through the sampling tube.
Table A.3 Zero drift and range drift
Calibration gas
Zero drift range drift
Zero gas measured value zero drift
Zero drift
ΔZ/CS
Standard gas measurement range drift
Range drift
ΔS/CS name
concentration
Start
Z0
finally
Zi
ΔZ=Zi -Z0
Start
S0
finally
Si
ΔS=Si -S0
Zero gas
CO
Note. The start indicates the test before, and finally indicates the test.
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