Flue gas is gas that exits to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. Quite often, it refers to the combustion exhaust gas produced at power plants. Its composition depends on what is being burned, but it will usually consist of mostly nitrogen (typically more than two-thirds) derived from the combustion air, carbon dioxide (CO₂) and water vapor as well as excess oxygen (also derived from the combustion air). It further contains a small percentage of pollutants such as particulate matter, carbon monoxide, nitrogen oxides and sulfur oxides. This article does not cite any references or sources. ... A flue is a pipe or channel for conveying exhaust gases from a fireplace, furnace, boiler, or generator. ... A furnace is a device for heating air or any other fluid. ... A boiler is a closed vessel in which water or other fluid is heated under pressure. ... A steam generator is a device used to boil water to create steam. ... A combustion reaction taking place in a igniting match Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ... A power station (also power plant) is a facility for the generation of electric power. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... It has been suggested that multiple sections of steam be merged into this article or section. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Particulates, alternately referred to as Particulate Matter (PM) , aerosols or fine particles are tiny particles of solid or liquid suspended in the air. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Nitrogen has six different oxides: Nitric oxide (NO) Nitrous oxide (N2O) Nitrogen dioxide (NO2) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen pentoxide (N2O5) The term nitrogen oxide is imprecise and can be used to refer to any of these or to a mixture of them. ... Sulfur oxide refers to one or more of the following: Sulfur monoxide (SO) Sulfur dioxide (SO2) Sulfur trioxide (SO3) This is a disambiguation page: a list of articles associated with the same title. ...

At power plants, flue gas is often treated with a series of chemical processes and scrubbers, which remove pollutants. Electrostatic precipitators or fabric filters remove particulate matter and flue gas desulfurization captures the sulfur dioxide produced by burning fossil fuels, particularly coal. Nitrogen oxides are treated either by modifications to the combustion process to prevent their formation, or by high temperature or catalytic reaction with ammonia or urea. In either case, the aim is to produce nitrogen gas, rather than nitrogen oxides. In the US there is a rapid deployment of technologies to remove mercury from flue gas - typically by adsorption on sorbents or by capture in inert solids as part of the flue gas desulfurization product. The word scrubber can mean:- The part of a rebreather breathing set which absorbs the carbon dioxide which the individual using the breathing set breathes out. ... An electrostatic precipitator (ESP), or electrostatic air cleaner is a particulate collection device that removes particles from a flowing gas (such as air) using the force of an induced electrostatic charge. ... Flue gas desulfurization is technology that employs a sorbent, usually lime or limestone, to remove sulfur dioxide(SO2) from the gases produced by burning fossil fuels. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Standard atomic weight 32. ...

Technologies based on regenerative capture by amines for the removal of CO₂ from flue gas have been deployed to provide high purity gas to the food industry. They are now under active research as a method for CO₂ capture for long-term storage as a means of greenhouse gas remediation.

There are a range of emerging technologies for removing pollutants emitted from power plants. As yet, there is very little performance data available from large-scale industrial applications of such technologies and none has achieved significant penetration of the enormous worldwide market.

See also

• Combustion
• Emission standard
• Exhaust gas
• Flue gas emissions from fossil fuel combustion
• Flue gas stacks
• Flue gas desulfurization (often referred to as FGD)
• Integrated Gasification Combined Cycle (often referred to as IGCC)
• Nitrogen oxides emission (often referred to as NOx)