Oxygen Probes

C+ Probe - For Atmosphere Control in Carbon Anode Baking Furnaces

Introduction

The C+ probe enables accurate, continuous real-time measurement of oxygen and temperature directly within the carbon anode baking furnace atmosphere. A design feature of the C+ probe is the use of special corrosion resistant sheath and electrodes. These materials have been proven in service to be resistant to the corrosive trace gases commonly found in a carbon anode baking furnace atmosphere. C+ probes have been in service for over one year of continuous use, with excellent accuracy and reliability.

Applications

The advantages of accurate measurement of the oxygen content of the furnace atmosphere include:

• Fuel savings - Optimum combustion depends on sufficient oxygen to burn all the combustibles, without waste of energy from heating excess air.
• Reduced process variability - Improved control of the air and fuel supply enables better control of temperature. Tighter control of the baking conditions reduces variability in the properties of the carbon anodes.
• Reduced air pollution - During the course of baking anodes, various volatile organic materials distil out of the anodes. Control of the oxygen content can ensure that these compounds are completely burnt in the furnace.

Specifications

The C+ probe is based on the SIRO₂ zirconia oxygen sensor. This all ceramic sensor is the world-wide industry standard for controlling furnace atmospheres.

Oxygen range	0.001% to 21%
Accuracy	10% of reading
Response time	<5 seconds
Operating temperature	700°C to 1000°C
Construction	Refractory stainless steel sheath with thermocouple head. Proprietary corrosion resistant electrodes
Output	Oxygen signal according to the Nernst equation. Optional K-type or R-type thermocouple
Connections	Cannon plug, other types available on request
Length	Available in 100 mm increments from 300 to 1200 mm

Installation

Note that the probe contains brittle ceramic components. Treat it as fragile: do not drop, knock or handle roughly.

The probe can be installed anywhere in the kiln or furnace, provided that the temperature at the tip is between 700 deg C and 1000 deg C. The probe will measure the oxygen concentration at the probe tip.

Seal the installation port well enough to avoid atmospheric air from flowing inwards and causing a local variation in the oxygen concentration.

Connections

Keep the probe head at a temperature less than 60 deg C.

Supply clean respirable reference air at a rate of 10 cm3/min to the connection provided on the probe head.

The electrical connections are:

Pin 1	Optional thermocouple
Pin 2	Optional thermocouple
Pin 3	Oxygen sensor internal conductor
Pin 4	Oxygen sensor external conductor

Output

The oxygen signal is according to the Nernst equation

pO2 = 0.209 exp(-46.42E/T)
where
pO2 = oxygen partial pressure in atmospheres
E = oxygen signal in mV
T = temperature in Kelvin

Maintenance

There are no user serviceable parts inside the probe.

Regularly inspect the sensor tip, visible through the gas inlets in the sheath, for dust. If it appears to be clogged, remove excess dust with compressed air or a soft brush. Do not insert hard objects in the gas holes or scrape the sensor tip, as this could damage the electrode material.

Ordering & Information

For further information please enquire, to Australian Oxytrol Systems or use the online Enquiry Form

Menu