HJ 629-2011Stationary source emission - Determination of sulphur dioxide - Non-dispersive infrared absorption method (English PDF)

2.86 - conversion factor for converting sulfur dioxide's mass concentration

TO the mass concentration under standard conditions.

8.1.3 Calculation of sulfur dioxide's emission rate

Where,

G - sulfur dioxide's emission rate, kg/h;

rho – mass concentration of sulfur dioxide in dry exhaust gas, (mg/m3);

Qsn - dry exhaust gas flow under standard conditions (273K, 101.325 kPa),

m3/h.

8.2 Result representation

The calculation results of sulfur dioxide's concentration and emission rate shall

be rounded off to three significant digits.

9.1 Precision

Six laboratories have determined the unified simulated gas samples of which

the sulfur dioxide concentrations are 64 mg/m3, 116 mg/m3, and 268 mg/m3

respectively.

Relative standard deviations in laboratories are respectively. 0.4%~3.4%,

0.3%~1.8%, 0.1%~0.8%;

Relative standard deviations among laboratories are respectively. 3.0%,

1.0%, 0.3%;

Repeatability limits are. 2.7 mg/m3, 2.8 mg/m3, 3.0 mg/m3;

Reproducibility limits are. 5.9 mg/m3, 4.1 mg/m3, 3.5 mg/m3.

9.2 Accuracy

Six laboratories have determined the certified reference gases of which the

sulfur dioxide concentrations are 146 mg/m3, 636 mg/m3, and 1403 mg/m3

respectively.

Relative errors are respectively. 0~1.5%, 0.1%~0.9%, 0.1%~0.7%;

Final values of relative errors are. 0.5%±1.1%, 0.4%±0.6%, 0.3%±0.4%.

10.1 The dew-point temperature of the sample gas must be lower than ambient

temperature. When sample gas has moisture, it shall use dehumidifier to

reduce the dew-point temperature to 5°C. The dehumidifier shall make the

determined sulfur dioxide's loss in the dehumidified gas not to be greater than

5%.

10.2 When determining sulfur dioxide, it shall choose the instrument of which

the ability of resisting negative pressure is better than negative pressure of gas

duct, so as to avoid the instrument's sampling flow reduces and causes the

determination result lower or unable to be determined.

10.3 When sample gas has sulfur dioxide or other aerial fog, it shall use mist

filter or condenser to filter.

10.4 Before and after determination each time, it shall check the tightness of

determination system, and use standard gas to calibrate.

10.5 The sample gas temperature that is directly imported into the analyzer

shall not be greater than 50°C.

11.1 In order to prevent the moisture in sampling gas being condensed in the

connecting pipe and in the instrument, which will interfere the determination,

the sampling tube and dehumidifier shall be heated to 120°C before sampling,

so as to prevent the moisture in the sample being condensed in the sampling

pipeline.

11.2 When connecting the sampling tube with heating and dehumidifying

devices to the instrument's air inlet, the connecting pipe line shall be as short

as possible. In case of using long pipe line, it shall prevent the moisture in the

sample gas being condensed.

11.3 The sampling gas shall be filtered before it is going into the analyzer, so

as to eliminate the particulate matter in the sampling gas. Before determination

begins, it shall check the dehumidifier and the gas pipeline, and clean the filter

for particulate matter of sampling preprocessor. Replace filtering material when

necessary. During determining, it shall always monitor the flow rate changes,

clean timely and replace smoke filtering device.

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