May-2022

Safe, optimised combustion with three critical measurements in one analyser

The AMETEK Thermox WDG-V is a combustion flue gas analyser designed to measure excess oxygen (O2), combustibles (CO+H2), and hydrocarbons (CH4+) in fired heaters, boilers, thermal oxidisers, and other combustion processes.

AMETEK

Article Summary

The AMETEK Thermox WDG-V is a combustion flue gas analyser designed to measure excess oxygen (O2), combustibles (CO+H2), and hydrocarbons (CH4+) in fired heaters, boilers, thermal oxidisers, and other combustion processes. Designed for safety and reliability, the WDG-V provides an additional layer of safety in burner management systems and safety systems with a SIL-2 capable excess oxygen measurement. Operators choose the WDG-V to ensure fast, safe, and efficient control of their combustion processes, even when using high hydrogen fuels.

Providing the operational air-fuel setpoint for the burner, the WDG-V leverages the highly reliable zirconium oxide technology to make the critical excess oxygen measurement. Unlike the ‘total oxygen’ concentration, the excess oxygen measurement represents the oxygen concentration after all combustible compounds in the stream are consumed, correlating directly with the ratio of air to fuel in the burner. Most fired equipment is operated with a slight excess of oxygen in the flue gas, and plant operators use the excess oxygen measurement as an important setpoint for safe combustion control.

For process safety, fuel efficiency, and emission reduction, a combustibles detector can be added as a secondary measurement to the WDG-V. By measuring the ppm levels of partially combusted emissions or ‘combustibles’ within the flue gas, the combustibles measurement offers a means to monitor and alert the onset of incomplete combustion during normal operation. High combustibles levels can cause potentially unsafe conditions and signal insufficient air at the burner. The combustibles detector provides a tangible safeguard in a single measurement and greater process visibility.

In addition to monitoring for safety, the combustibles detector can also unlock a mechanism for fuel efficiency and emission reduction when monitored together with the excess oxygen reading. The excess oxygen measurement, by itself, offers an operational setpoint for the air-fuel ratio. However, the combustibles measurement provides context to lower the excess oxygen setpoint to a safe yet more optimal point. At this optimised oxygen setpoint, less fuel is needed from the burner, and as a result, fewer carbon emissions are generated. The WDG-V provides both measurements in one sensor to ensure safety, energy efficiency, and optimised combustion.

In addition to the combustibles detector, a methane/hydrocarbons detector can be included as a third measurement to the WDG-V. Unlike the ppm measurements of the combustibles detector, the methane/ hydrocarbons detector provides per cent level measurements of hydrocarbons, and it operates hot enough to crack and measure methane as well. With its catalytic elements, this third detector can also measure per cent levels of hydrogen if end users are using pure hydrogen or high hydrogen fuels. This detector is especially useful in the event of major fuel leaks or loss of flame during start-up and normal operation, as the combustibles detector does not operate hot enough to monitor for methane or other small, unburnt hydrocarbons. Ultimately, through these three measurements in one unit, the WDG-V empowers end users with full visibility of the health and safe operation of their combustion process