ABB AO2000-Fidas24 - Caldos25, Caldos27: Substitute Gas Calibration

AO2000 CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B 237
Caldos25, Caldos27: Substitute gas calibration
Example
Substitute gas calibration in the Caldos25 and Caldos27 is described using
the example of "CO
2
measurement in flue gas".
CO
2
measurement in flue gas
The composition of the various combustion products in the sample gas is
known
2
measurements of flue gas from single-component firings. The flue
gas out of the cooler primarily contains CO
2
, O
2
, N
2
and Ar. CO
2
cannot be
measured in mixed-firing flue gases.
Test gases
The following table shows test gases for the calibration of the 0 to 20 vol.%
of CO
2
measurement range:
Fuel Test gas composition in vol.% for
Zero Middle concentration Span
CO
2
O
2
N
2
Ar CO
2
O
2
N
2
Ar
Gas Air 10 3 86 1 20 – 79 1
Oil Air 10 8 81 1 20 – 79 1
Coal Air 10 10 79 1 20 – 79 1
Calibration with substitute gas
Since the test gases in this table are not available everywhere, the analyzer
module can be factory-set for calibration with a substitute gas. In this case
an additional measurement range is calibrated for 0 to 20 vol.% of CO
2
in N
2
(N
2
and CO
2
/N
2
mixtures are available practically everywhere).
Measurement ranges
Component 1 CO
2
in flue gas Meas. range 1 0 to 10 vol.%
Meas. range 2 0 to 20 vol.%
Component 2 CO
2
in N
2
(substitute gas) Meas. range 1 0 to 20 vol.%
Calibration data
Calibration method Substitute gas calibration
Zero component Component 1 Meas. range 1 or
Component 2 Meas. range 1
Span component Component 2 Meas. range 1
Calibration
• Calibrate zero with air (component 1) or N
2
(component 2).
• Calibrate span with test gas 18 vol.% CO
2
in N
2
.
Other measurement tasks
For other measurement tasks select the test gases and measurement ranges
in a similar manner according to the sample gas composition.