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Bristol OxyTrim
- Oxygen Measurement & Control Probe

Bristol Oxytrim oxygen probes are designed and manufactured by Bristol Babcock Controls NZ for boilers, kilns and furnace installations.

Oxytrim probes utilise a Zirconia sensor developed by Australia's CSIRO. Bristol Oxytrim's accurate, reliable and rugged design provides a low cost and compact solution for continuous monitoring or control in new or retrofit combustion control systems applications.

Oxytrim' "in-situ" oxygen probes are designed to operate in harsh environments (high temperature, corrosive gases, dirty atmospheres and thermal shock) for extended maintenance-free periods and use ambient air as reference air supply source. For gas analysis below 800^oC, OxytrimH , incorporating an integral heater provides the solution.

Oxytrim can accommodate fuel temperature, pressure, specific gravity, viscosity and calorific value combustion variables via continuous on-line closed-loop control thereby eliminating fuel wastage and environmental pollution.The Oxytrim probe utilises a zirconia membrane sensor, in a ceramic tube within the probe's specially designed protective sheath. When there is a difference in the oxygen concentration either side of the zirconia pellet, the pellet acts as an electrochemical cell and generates a voltage according to the Nernst equation:

E = RT/4F * ln (P1/P2)

E = voltage in Mv

R = gas constant

T = temperature, zero K

F = Faraday constant

P1= oxygen partial pressure side 1

P2 = oxygen partial pressure side 2

Utilising atmospheric air as the internal reference gas (20.9% oxygen), the relationship simplifies to:

E = 0.0496 T log(P/0.209)

A decrease in oxygen concentration increases the mV output and vice versa. This results in increased sensitivity at low oxygen concentrations.

Oxytrim can be tailored to meet particular plant configuration and control installations for most furnace, kiln and boiler oxygen measurement and control applications.

Oxygen Probe

The Bristol Oxytrim In-Situ Oxygen Probe Systems have been developed basically to monitor partial pressure (volumetric content) of oxygen in a mixture of gases (whether as free oxygen or in equilibrium). Some of the applications are

-Monitoring Oxygen (excess air) to optimise combustion in Boilers, Furnaces, Kilns, etc. to conserve fuel and reduce atmospheric pollution.

-Monitoring Oxygen (generally in ppm / ppb) in gas generators e. g. in Nitrogen, Argon, endo/exo gas, etc.

-Carbon potential in metallurgical furnaces, e.g. gas carburising, carbonitriding, hardening, sintering.

Giving dramatic savings in numerous plants worldwide:

• •Improved fuel consumption

• •Automatic on-line control - reduced operating costs

• •Rapid response closed loop system - boosts quality control

• •Control precision - reduced conditioning and downtime, fewer burnouts and longer furnace life

• •Simple and easy to install-rapid capital outlay recovery

• •4 Models available-length 150mm to 2metres

• BAT	Ambient Air to 400oC
  BLT	350oC to 700oC
  BST	600oC to 1100oC
  BHT	1000oC to 1400oC

Probe construction is robust to withstand harsh environments. Probes are virtually maintenance-free and provide highly accurate control of furnace atmospheres. Additional benefits are faster furnace cycles with corresponding fuel economy.

Monitor/Controller portable unit is a handy aid for combustion engineers and maintenance teams. The fixed monitor/controller may include a recorder for continuous display of oxygen content and furnace temperature. Correctly used, this is invaluable for establishing preventative maintenance and avoiding costly overhaul programmes. An Explosive Mixture Present feature is included as standard to warn of plant component failure and for improved operator safety.

Trim Pack is an air or fuel line actuator. Air line actuator VA is included between the main modulating damper and either the continuous air damper, process gas generator or other regulating device. Fuel line actuator VF is fitted into the fuel or process gas train and bypasses the existing valve. No additional wiring required, the trim pack power is provided by the monitor/controller.

Umbilical Cable links the probe and monitor/controller and is fitted with all necessary connectors.

Bristol Oxytrim Systems are self-contained; they do not involve modification to existing plant wiring. All units are readily installed by operating staff or maintenance teams - no special calibrating equipment or sampling lines are required.