Surface Stabilized Combustion Engineering & Technology
Premixed, metallic surface-stabilized combustion firing inside a duct
Low NOx, FireStar Burner Module
ALZETA® Corporation has pioneered the development pre-mixed surface stabilized combustion. Surface stabilized combustion is accomplished with porous surfaces, in which premixed fuel and air uniformly permeate through the surface and combustion takes place only along the outermost layer. One inherent characteristic with all of ALZETA’s surface stabilized combustion burners is low nitrogen oxides (NOx) emissions. Low NOx levels are achieved by creating a homogeneous mixture of fuel and air, with a specific fuel/air ratio to produce a desired adiabatic flame temperature. Since the primary NOx formation mechanism is the thermal fixation of atmospheric nitrogen and oxygen at elevated temperatures, controlling and lowering the adiabatic flame temperature is essential to having predictable and minimal thermal NOx formation.
ALZETA achieves lower adiabatic flame temperature by operating leaner (more excess air). But lean operation often means combustion instability, with high CO emissions and irregular flame patterns. This is avoided when combustion stabilizes on a relatively large surface with many points for flame attachment. As combustion occurs uniformly along the surface, the shape of the surface burner defines the shape of the flame.
Adiabatic flame temperature can be further reduced by increasing the air ratio, or by diluting the air-gas mixture with an inert such as flue gas. And since any localized zones of higher adiabatic flame temperature can rapidly increase the rate of NOx formation, having a very uniform air and gas premix to achieve uniform temperature along the surface is essential to minimizing NOx. Another advantage of premix burners is that the fuel and air is combined at a single location before combustion, unlike most conventional burners in which combustion occurs at a number of point as the fuel and air mix.
Premix surface stabilized combustion technology from ALZETA such as the FireStar™ , Duratherm™, CSB™ , Pyromat™, NanoSTAR™ and PYROCORE® burners have revolutionized the combustion engineering industry.