HJ 870-2017Stationary Source Emission - Determination of Carbon Dioxide - Non-Dispersive Infrared Absorption Method (English PDF)

3.1 Zero gas

The gas with no measurement components or less than the specified value; the concentration of other component does not interfere with the measurement component results or the interference of the measurement component may be negligible.

3.2 Calibration span

6.1 Standard gas of carbon dioxide

The commercial certificated standard gas with uncertainty <=2%.

6.2 Zero gas

Nitrogen gas with purity >=99.99% or clean air not interfering the determination.

7.1 Carbon dioxide detector by non-dispersive infrared absorption method

7.1.1 Composition

Instrument consists of: analyzer (including gas flow meter and flow control unit, air pump, detector, etc.), sampling tube (including dust filter device and heating and heat preservation device), air guiding pipe, dehumidifying device, portable printer, etc.

7.1.2 Performance requirements

a) Calibration error: not exceeding ±5%;

b) System bias: not exceeding ±5%;

c) Zero drift: not exceeding ±3%;

d) Span drift: not exceeding ±3%;

e) Has the function to eliminate the interference;

f) The dehumidifying device shall meet the requirements of GB/T 16157;

g) Has the function to show the sampling flow rate; the measurement range and accuracy of gas flow meter shall meet the requirements of the instrument;

h) The heating and heat preserving temperature of the sampling tube: it may be set or adjusted within 120°C~160°C.

7.2 Steel cylinder of standard gas

It is equipped with adjustable pressure reducing valve, adjustable rotor flowmeter and air guiding tube.

7.3 Gas collecting bag

8.5 Sample determination

8.5.1 Place the front end of the sampling tube of the instrument in the exhaust pipe;

block the sampling hole, so that it does not leak gas.

8.5.2 Start the air pump; conduct sampling determination according to the sampling

flow specified by the detector. After the detector is stable, save the measurement data in minutes; take the average value of the measure data for at least continuous 5 minutes as the one measurement value.

8.5.3 After the end of one measurement, use the zero gas to clean the instrument according to the instruction manual of the instrument.

8.5.4 After obtaining the measurement result, use zero gas to clean the instrument.

When the indication value returns to near zero point, turn off the power and finish the measurement.

9.1 Results calculation

9.1.1 Calculation of exhaust flow rate

According to the provisions of GB/T 16157, calculate the dry exhaust flow rate Qsn (m3/h) under the standard state (273K, 101.325kPa).

9.1.2 Calculation of carbon dioxide concentration

The concentration (g/m3) of carbon dioxide in the stationary source emission shall be calculated as per the following formula:

Where:

rho – mass concentration of carbon dioxide in the dry exhaust under the standard state, in g/m3;

omega – volume concentration of carbon dioxide in the measured exhaust determined by the instrument, in %.

9.1.3 Calculation of carbon dioxide emission rate

The relative standard deviations in the laboratory are: 0.05% ~ 0.12%, 0.01% ~

0.20%, 0.04% ~ 0.13%;

The relative standard deviations among laboratories are: 3.4%, 2.1%, 3.2%;

The repeatability limits are: 0.04%, 0.06%, 0.02%;

The reproducibility limits are: 1.3%, 1.0%, 0.52%.

10.2 Accuracy

Determination of carbon dioxide standard gases at concentration levels of 5.01%,

15.1%, 20.0% in 6 laboratories:

Relative errors are: -1.9% ~ 2.0%, -1.4% ~ 1.7%, -0.08% ~ 0.06%;

Final values of relative errors are: -0.17%±2.6%, -0.10%±2.1%, 0.02%±0.10%.