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3.3
Principle of operation
The modular measuring system consists of the following components:
• Heated sampling probe
• Sampling line (maximum 50 m)
• Sample gas cooler
• Sample gas pump
• 1 to 3 differently configurable analyzers
• Cabinet air conditioning unit (optional)
The detailed gas path of sample and calibration gases is shown in the gas flow diagram
(Gas flow diagram (Page 71)).
The sample gas is removed by a heated sampling probe with ceramic filter. The sample
gas is sucked at through the sampling probe -WS1 through the sample gas pump -GP1
and the heated sample gas line -EH1 (option) into the first stage of the sample gas
cooler. There, the sample gas is cooled to approximately 4 °C dew point. The heated
sample gas line must be routed to the cooler with a downward slope, so that any
condensate droplets that occur can run down toward the sample gas cooler without
forming water pockets. Condensate droplets present in the sample gas line upstream
from the cooler are therefore generally of no significance. The sample gas then flows via
the 3/2-way solenoid valve -QV1 and the 3-way ball valve -RB1 into the second cooling
stage. A fine filter is installed in the second stage of the cooler.
The condensate produced in the cooling stages is discharged into the condensate tank -
CT (option) by the built-in hose pumps. The condensate collecting tank is equipped with
a level monitor -BS4, which sends a message to the controller when a defined level is
reached.
After the sample gas cooler, the gas path splits into various partial lines in order to
supply up to 3 analyzers with sample gas in parallel. An additional partial flow lets the
excess sample gas flow out via a bypass. To protect the analyzers, a condensate blocker
is located directly upstream from the analyzers; it closes off the gas path when
condensate breaks through.
A three-way valve is installed upstream from the pump for introduction of zero gas for
the automatic zero calibration via ambient air. A second three-way valve is installed
downstream from the pump for introduction of zero and calibration gases from
compressed gas cylinders. This three-way valve can introduce calibration gases from
compressed gas cylinders at set times for autocalibration of the zero point or reference
point. Alternatively, calibration gases can be supplied manually via a subsequent three-
way ball valve.
The gas is collected from the gas outlets of the analyzers and discharged from the
cabinet via the sample gas outlet (screwed gland for tube DN10/12). Starting from the
sample gas outlet, the sample gas must be discharged without back pressure or
pressure variations.
Set CEM CERT
Operating Instructions, 03/2020, A5E34491309-11
Description
3.3 Principle of operation
21
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