Zirconia Probe O2 and CO

Zirconia Probe O2 and CO

The usage of the T2550 ZI (HighZ) Zirconia Input Module and Zirconia Function Block requires some additions to make it usefull.

First of all the input is calibrated at 800 and 1200mV resulting in a small non-linear offset around 0mV.
However this small offset may lead to 10% error in the Oxygen %O2 calculation.
A Characteriser block can eliminate this offset.
Using a calibrated source one needs to measure the offset at various points and enter these values in the characteriser block.
This has to be repeated for each individual ZI module.

Normally a Zirconia Probe ( ZrO ) is placed in the exhaust of the flue gas and operate between 700 to 1200°C
For temperatures up to 1500°C the probe has to be constructed specially.
At these temperatures the probe will age more rapidly (due to depletion) and life time expectancy can go down to 3 months.

Observed is a very wild (stochastic) input signal at elevated temperatures.
This can be catered for using a Rate_Limiter Block as Low Pass Filter.
Automatic Impedance determination can not operate properly under these conditions.

The Oxygen calculation can be done directly in the Zirconia FB.
However I rather put the Nernst Equation in an Expression block.

When all Oxygen is used CarbonMonoOxide ( CO ) will be generated.
Insulation material and bricks will deteriorate under these Reducing Atmospheric conditions.
Above 200-250mV input measured we asume the CO contribution.
The ZrO probe input can rise to 600mV for 10% CO.
The %CO can be estimated using the same Nernst Equation with different parameters.

For the Glass Industry Burner Applications we alarm this situation.

In Heat Treatment Market the calculation has to be used carefully since other influences are present.

For a detailed strategy please ask me.
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