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In atmospheric chemistry, NOx is shorthand for nitric oxide (NO) and nitrogen dioxide (NO2), the nitrogen oxides that are most relevant for air pollution. [1][2] These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone. NOx gases are usually produced from the reaction between nitrogen and oxygen ...
This porosity is what gives the catalyst the high surface area needed for reduction of NOx. However, soot, ammonium sulfate, ammonium bisulfate, silica compounds, and other fine particulates can easily clog the pores. Ultrasonic horns and soot blowers can remove most of these contaminants while the unit is online. The unit can also be cleaned ...
Null cycle. In atmospheric chemistry, a null cycle is a catalytic cycle that simply interconverts chemical species without leading to net production or removal of any component. [1] In the stratosphere, null cycles and when the null cycles are broken are very important to the ozone layer. One of the most important null cycles takes place in the ...
Ozone is least concentrated in the ground layer (or planetary boundary layer) of the troposphere. Ground-level or tropospheric ozone is created by chemical reactions between NOx gases (oxides of nitrogen produced by combustion) and volatile organic compounds (VOCs). The combination of these chemicals in the presence of sunlight form ozone.
Thermal oxidizers are typically used to destroy hazardous air pollutants (HAPs) and volatile organic compounds (VOCs) from industrial air streams. These pollutants are generally hydrocarbon based and when destroyed, via thermal combustion, they are chemically oxidized to form CO 2 and H 2 O. Three main factors in designing the effective thermal ...
Selective non-catalytic reduction (SNCR) is a method to lessen nitrogen oxide emissions in conventional power plants that burn biomass, waste and coal.The process involves injecting either ammonia or urea into the firebox of the boiler at a location where the flue gas is between 1,400 and 2,000 °F (760 and 1,090 °C) to react with the nitrogen oxides formed in the combustion process.
In fuel biasing, combustion is staged by diverting fuel from the upper-level burners to the lower ones or from the center to the side burners. The aim is to create a fuel-rich lower or central zone and a fuel-lean upper or side zone in order to achieve complete burnout. The technology lowers the flame temperature and improves the balance of the ...
Crankcase ventilation system. A crankcase ventilation system (CVS) removes unwanted gases from the crankcase of an internal combustion engine. The system usually consists of a tube, a one-way valve and a vacuum source (such as the inlet manifold). The unwanted gases, called "blow-by", are gases from the combustion chamber which have leaked past ...