Review of Air Toxics from Combustion Sources

摘要

Control of air toxics and by-products from the combustion processes is the subject of this paper. Air toxics are those substances that are acutely hazardous or have a potential to cause harm after long term exposure. Typical examples include carcinogens such as arsenic or mercury (a neurotoxin). Other by-products often associated with poor combustion practices are also discussed. These include the condensed ring aromatic structures often associated with incomplete combustion. Polycyclic Aromatic Hydrocarbons (PAH) represent one class of combustion by-products that can be generated by less than ideal combustion conditions (i.e. poor mixing). Formaldehyde, a topic of recent regulatory interest for gas turbines, is a combustion intermediate that is part of every hydrocarbon oxidation process. It will be shown that its impact, especially from gas turbine sources, is essentially negligible. Controlling the release of these emissions into the atmosphere is achieved using several different approaches. The simplest approach is a fuel change, where a higher quality or grade of fuel is burned. However, high quality fuels are not universally available. Also, the lower associated fuel costs with poorer fuel grades can be a dominant factor in the fuel selection process, thus requiring some mechanism for reducing emissions other than fuel switching. This review will discuss fuel choice, technology fixes and component designs that will provide power generators with the ability to serve market needs while complying with restrictive environmental requirements.