rauchgas

Rauchgas, in English often translated as flue gas or exhaust gas, is the gas released from a combustion process. It originates from burning fuels such as coal, oil, gas, biomass, or waste in boilers, furnaces, or engines. The gas mixture exits through a stack or exhaust system, and its composition depends on the fuel, the air–fuel ratio, and the presence of pollutants.

The major components are nitrogen from the surrounding air, carbon dioxide and water vapor formed during combustion, and residual oxygen. In complete combustion the gas is dominated by N2, CO2, O2, and H2O; in imperfect combustion CO and larger hydrocarbon compounds may be present. When fuel contains sulfur, sulfur oxides (SOx) can be produced; reactive nitrogen compounds (NOx) are formed at high temperatures. Particulates or soot may also be present, especially from burning heavier fuels.

Rauchgas is subject to monitoring and regulation. In many countries operators measure key pollutants with continuous emission monitoring systems (CEMS), tracking CO2, CO, O2, NOx, SO2, and particulates. Orsat analysis or modern gas analyzers provide laboratory measurements of gas fractions for process control and compliance.

Treatment technologies exist to reduce environmental impact before releasing rauchgas to the atmosphere. They include particulate removal (electrostatic precipitators, baghouses), sulfur removal (wet or dry scrubbers), NOx reduction (selective catalytic or non-catalytic reduction), and CO or hydrocarbon oxidation. Energy efficiency and fuel choice influence rauschgas composition and emissions.

The term is also used in contexts such as waste incineration, gasification, and industrial processes to refer to any combustion-derived gas stream. Understanding rauchgas composition is essential for process control, energy management, and environmental protection.