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The combined probe measures four different quantities
simultaneously.
The dust concentration is determined according to the
tribo-electric measuring principle. The tribological probe measures
the charge on the particles that strike the rod. Due to the
measurement principle, this charge flow is, without any compensation
calculation, dependent on the flow velocity and the concentration of
the dust in the flue gas.
The measurement of the volume flow works on the
differential-pressure principle. For this the probe has two chambers
separated from one another, between which a pressure difference is
established in the directional approaching flow. Due to the special
shape of the probe, the largest possible differential pressure is
produced and the linearity of the measurement signal referred to the
flow is guaranteed.
The absolute pressure in the flue gas is sampled in
one chamber of the probe and measured by a piezo-resistive pressure
transmitter.
The temperature is measured in a separate chamber
within the probe directly in the core flow of the flue gas by a
Pt100 resistance thermometer. The raw data is processed locally at
the measuring point and transferred via a bus interface up to 1000 m
to an operating and evaluation unit with display or to a process
control system. |