Its purpose is to determine the optimum amount of air needed for combustion, ensuring the fuel is used efficiently, potentially saving thousands of dollars.
Too little oxygen means that more fuel is needed, while too much oxygen results in a fast burn, but produces a high level of emissions such as mono-nitrogen oxides (NOx), sulphur oxides (SOx), carbon dioxide (CO2) and carbon monoxide (CO). The XZR500 monitors the exhaust gas for excess oxygen ensuring that the conditions are kept close to stoichiometric (ideal) levels.
The XZR500 uses Michell’s Zirconium Oxide Oxygen Sensor, which has a metallic sealed reference (MSRS) to give long-term reliability. The combination of this type of sensor, placed in an isothermal oven within the analyzer (not the probe), negates the effects of varying, high temperatures as well as the corrosive nature of the gas. This also reduces time spent on maintenance: if a sensor needs replacement, this can be done within minutes without interrupting the process. The MSRS provides its own reference meaning a single calibration gas can be used.
The XZR500 has a control unit which can be placed at ground-level for convenience, a sensor head close-coupled to the stack for ease of installation and quick response and a variety of probe materials allowing a wide range of applications to be addressed with ease and confidence.
For most applications the probes use the Pitot effect to extract non-conditioned sample gas from the process to the sensor head and back to the flue. Placing the probe as close to the burner as possible gives accurate readings whereas installations further down the process have the risk of ambient air mixing with the sample and providing false readings. The XZR500 has ceramic probes capable of operating effectively in temperatures up to 1300°C.
Typical applications for the XZR500 include combustion efficiency for boilers, industrial waste incinerators and crematoria. When operated in extremely dirty applications, such as coal-fired power stations the XZR500 can be offered with a blow-back mechanism for increased reliability in readings and reduced manual intervention.