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System Component Description
Pneumatic Panel
Figure 7–3. Pneumatic Panel
Sample mode
In the sample mode (normal operation) the status of the sample valve is
open, and all other control valves are closed. Flue gas is pumped through a
pre-filter (20 micron), heated probe barrel (stinger), primary filter (2
micron), heated sample line, and heated optical gas cell of the FTIR
analyzer. Exiting the optical cell, the sample flow is diluted with zero air
and dumped to the exhausted tube.
Blowback
During blowback mode, sequentially, the sample valve is closed, and the
three-way solenoid control valve inside the probe head is energized to be
open. The pressurized air out of the accumulator tank is rapidly released
into the heated stinger to blowback through the pre-filter. Depending on
the particulate loading in the tested stack, the blowback can be executed
multiple times per day.
Instrument
During the instrument background scan and flowback mode, the sample
control valve is closed, and the instrument zero control valve is opened.
Background Scan
The CO
free zero air directly flows into the optical cell. Subsequently, a
2
and Flowback
zero background spectrum is collected. In parallel with the instrument
valve operation, the blowback control valve is triggered to perform system
blowback for 20 seconds, and then closed. Subsequently, the flowback
control valve is triggered to be open. Zero air flows back to the stack via the
sample line, primary filter, stinger and pre-filter at 4 LPM. Once the
background spectrum collection is finished, the flowback valve is closed,
the sample valve is opened, and the instrument zero valve closed. This
mode should be executed once every day for collecting instrument
background spectrum.
Thermo Fisher Scientific
Omni FTIR Multi Gas CEMS Instruction Manual
7-5
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