System Description
Installation and Operation Manual - COMTEC
®
/
OXITEC
®
DustEx
2
Doc.-ID: COM_OXI_Dust_11022020
1.3
Measuring principle
The DustEx analyzer system consists of an in-situ probe which is installed in a duct to measure non-combustible
process gases and of an electronic unit for voltage and gas supply, as well as for signal processing.
The O
2
sensor of the COMTEC 6000 is at the tip of the probe and is regulated to 800 °C and works on the zirconium
oxide principle of measurement. Here, a mV signal between the reference gas side of the sensor (inside, instrument
air 20.95% O
2
) and the measured gas side is measured, which depends logarithmically on the ratio of oxygen partial
pressures on both sides of the sensor. The mV signal is converted according to the Nernst equation into oxygen
partial pressure within the process gas, whereby the O
2
concentration is determined in the process gas. Gas-tight
separation of reference air and process gas is of particular importance.
In addition, for the COMTEC 6000 DustEx, the CO
e
sensor at the tip of the probe detects combustible, gaseous
molecules whereby the measured value corresponds to the CO equivalent (CO
e
= CO equivalent). This value can be
used as an indication of the combustion efficiency. A high COe value correlates with poor efficiency because a
portion of the fuel is not completely oxidized. The InSitu sensor is in contact with the sample gas with both electrodes.
These catalytically active electrodes cause oxidation of the non-oxidized gas molecules, so that a voltage is
generated between the electrodes, which depend on the COe concentration. Thus CO, H2 and CxHy (Hydrocarbons)
can be measured.
1.4
Intended use
Info
The OXITEC
®
5000 GasEx analyzer measure in flue gases of combustion plants or in comparable inert
gas mixtures. If oxidizable gas components are contained in these processes, contact ENOTEC.
For reasons of safety and the possibility of accidents, unauthorized conversions and modifications of the
system are prohibited..
Warning
The system cannot be used to determine the O
2
or O
2
/CO
e
concentration in combustible gases or in a
location where combustible gases are present as the measuring cell temperature of 800°C could present
an explosion hazard!
Caution
The maximum ambient temperature for the electronics is 55 ° C (131 ° F) and the terminal box on the
probe 70 ° C (158 ° F). These ambient temperatures must not be exceeded in any case. For use at high
ambient temperatures, check with ENOTEC!
Warning
The minimum concentration of O
2
in flue gas should under normal process conditions, not be less than
0,5%.If the O
2
concentration is regularly below 0,5%, we recommend the option of
CSP (Cell Surface Protection)
to protect the O
2
sensor (for OXITEC 5000 DustEx only).
1.5
Safety Hazards
Warning hot surface
During operation, the temperature of the probe filter head and of other parts exposed to flue gas is
150°C - 800°C (302°F - 1472°F). Direct contact with the hot parts when dismantling or maintenance will
cause severe burns!
The probe may only be removed with heat-insulated gloves. Before removing the probe, always switch off
the supply voltage of the electronic system. After removal, store the probe in a safe, protected place and
wait until it has cooled down below 35°C (95°F).
1.6
Disruption of the Process
The analyzer has to be kept in operation also if the process is disrupted or the plant is powered off
temporarily (e.g. at night or during the weekend). Frequently cooling down and heating up of the probe results in
thermal stress of the hot probe parts (heater, thermocouple and sensor) and reduces their product life. ENOTEC will
not accept any responsibility for resultant damage.