ABB GAA330-M, Руководство по эксплуатации

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GAA330-M EMISSION MONITORING SYSTEM | OI/GAA330-M-EN REV. C 67
Calibrating the analyzer system
CAUTION
Only persons familiar with the calibration of comparable analyzer systems
are certified as being capable of such work and should work on the sys-
tem.
NOTE
Calibration of the analyzer system has to be performed on board every
6 to 12 months with test gas, in accordance to agreement with class.
Conversion of concentration values
Care has to be taken, that the certified test gas used has to be specified in
% by volume. In case it is specified in volume by mole there has to be a con-
version as following:
Vol
C
volume fraction of the component
X
C
mole fraction
m
C
molar mass of the component
ρ
C
density of the component in the reference state
X
T
mole fraction of the component in the reference state
ρ
T
density of the carrier gas in the reference state
m
T
molar mass of the carrier gas
Basics
The purpose of the calibration (adjustment) is to scale the analyzer with a
reference normal. This reference normal can be a (certified) test gas or a
built-in calibration cell.
When calibrating SO
2
with infrared analyzers, some characteristics have to
be considered. Firstly, SO
2
is a water-soluble gas, which means that parts of
the gas may be solved in water. On the other hand, SO
2
is overlaid by the
water signal in the infrared range. Therefore, it is important that the water
content in the measured gas is constant. This is achieved by the gas cooler,
which stabilizes the output to a constant dew point of 3 °C below the en-
trance dew point. The error caused by the overlay of the constant water
signal is compensated in the analyzer by shifting the zero point.
In continuous operation you will also get a lossless operation, as long as the
gas concentration and the inlet humidity do not vary significantly.
Preconditions
•
Ambient air temperature: +5 °C to +40 °C
•
Flow from test gas bottle has to be as similar to the flow via the mem-
brane pump as possible. The flow of the test gas bottle can be regulated
via the pressure valve on top of the bottle.