#43 - Monitoring Oxygen and Carbon Monoxide for Maximum Boiler and Furnace Efficiency

Most fuel engineers know that low excess air firing on a boiler or furnace is far more efficient than the high excess air firing normally recommended by manufacturers of these processes. The high excess air is to ensure against stack smoking due to burner air and fuel distribution tolerances and changing weather conditions, etc. Because of this, many plants are operating with far more excess air than is required to burn the fuel, resulting in wasted energy and fuel dollars. In addition, high excess air can result in boiler tube and radiant tube failures.

Maximum fuel savings is achieved by reducing this excess air and the proportionate volume of flue gases going out the stack by increasing the CO content to about 120 PPM. This will result in a corresponding oxygen reading anywhere from about 0.6% O2 to 7% O2 depending on fuel used, burner condition and firing rate.

When operating the burners with the overall CO level between 100 and 200 PPM, there is also a significant reduction in emissions. The opacity will usually be less than 3%. NO levels can be reduced from 350 PPM at 20% excess air to 275 PPM at 3% excess air. SO3 reduction is directly proportional to excess air and can be reduced from 40 PPM to 6 PPM when reducing excess air from 20% to 3%.

The NOVA Model 360K and 360TK Portable Combustion Analyzers have been designed to detect and digitally display flue gas oxygen and CO. In addition, a high range switch on CO allows the operator to continue to observe high CO levels that may have over ranged the 0-2000 PPM low range scale.

In the 'T' versions, a special thermocouple probe and separate temperature readout are supplied to quickly determine combustion efficiency from a graph supplied in the operator’s manual. This can also be accomplished with any model with the use of a separate stack thermometer.

Model 360 brochure…

We make gas analyzers for oxygen, hydrogen, carbon monoxide, carbon dioxide, methane, and many other atmospheric gases. We provide gas analysers for syngas, landfill gas, purity gas, biogas, and others.

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