Combustion Catalog | Fives North American

Product Overview | 4211 EcoFornax ™ LE

The LE is designed to meet the increasingly-more-stringent global low emission requirements. 15-20 ppmdv NOx is easily achieved. FGR may be added to the 4211's oxidant stream to achieve even lower NOx emissions when needed. Current installations in water tube boilers at less than 7 ppmdv (0.008 lb/ million Btu). Standard sizes are available with capacities ranging from 4-300 mm Btu/h HHV. Larger sizes also available.

— Ultra Low NOx with or without the use of flue gas recirculation (FGR) depending on emissions required — For processes 1400 to 2400°F such as boilers, process heaters, and other applications requiring

— Thermal Fluid Heaters — Boilers — Process Heaters — Incinerators APPLICATIONS

Figure 2. The Magna-Flame LE is a staged fuel burner design with lean burn primary combustion zone. The balance of the fuel is injected downstream.

CONSTRUCTION The LE burner is sturdily constructed of steel, stainless steel, and refractory to withstand the operating environment. Optional corrosion-resistant alloy construction may be selected to handle fuel gases with sulfur or other corrosive constituents. Precision-cast silicon carbide/mullite-mix primary mixer tube extensions are cast into the dense refractory reaction chamber facing, keeping the metal mixer parts remote and protected from flame radiation and heat soak. The 3000°F dense castable reaction chamber wall structure contains the four stainless steel secondary injectors which protrude to discharge just past the hot face of the refractory. As the reaction chamber is typically of greater length than the furnace’s refractory wall thicknesses, some portion of it will extend back from the burner mounting cold face. The mounting flange can be located to match the wall thickness for ease of installation. While this requires extra room for the burner footprint past the furnace wall, it allows a smaller overall furnace chamber with flame envelope containment.

OPERATION The LE is a fuel-staged burner with a lean primary combustion zone. Secondary fuel is directly injected into the oxygen-rich primary zone POC where it combusts to achieve the final desired combustion ratio. The LE’s combustion air supply is split between main (primary) air and radial air connections. The fuel gas supply is divided between three gas connections: radial, primary, and secondary. The radial gas is used at start-up and for stabilization of the primary (lean) core. The primary gas feeds the mixers of the lean primary zone, typically operated at 60-70% XSA. The secondary gas exits injectors integrated into the primary zone reaction chamber structure to mix with the lean premix flame/ POC at the outlet of the reaction chamber. Final air/fuel ratio is typically at 10-15% XSA (2- 3% O2 in the stack). Stoichiometric turndown is about 4:1. Higher turndowns are obtained by progressively increasing the excess air rate (thermal turndown). Typical design high fire air pressure is 15"w.c. max. Minimum primary air pressure required for continuous operation is 0.75"w.c. Typical design gas pressure is 8 psig.

Bulletin 4211 Page 2

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