NOx - Definition and Overview

NO_x is a generic term for the various nitrogen oxides produced during combustion. They are believed to aggravate asthmatic conditions, react with the oxygen in the air to produce ozone, which is also an irritant and eventually form nitric acid when dissolved in water. When dissolved in atmospheric moisture the result can be acid rain which can damage both trees and entire forest ecosystems.

Three primary sources of NO_x formation in combustion processes are documented: prompt NO, fuel NO and thermal NO. Thermal NO_x formation, which is highly temperature dependent, is recognized as the most relevant source when combusting natural gas.

Technologies such as flameless oxidation (FLOX®) and staged combustion significantly reduce thermal NO_x in industrial processes.

The Environmental Protection Agency (EPA) regulates and enforces NO_x emission limits in the U.S. in accordance to legislation passed by Congress.

The Kyoto Treaty, ratified by 54 nations in 1997, calls for a substantial world wide reduction of green house gas including NO_x.