The emission of contaminants in the combustion processes of various industries is an important issue to consider if we want to comply with regulations that protect public health and the environment.

The Fives North American LNI (low NOₓ injection) burner system takes advantage of the largest source of ‘free’ flue gas recirculation, the furnace itself, to produce exceptionally low NOₓ emissions in high temperature systems.

Learn more about the characteristics of these burners and their benefits in this article.

Article content:
The best combustion technology
How does it work?
Benefits of HiRam LNI technology

The best combustion technology

Low NOₓ injection (LNI) of fuel and air in the furnace chamber provides the highest potential efficiency and the lowest NOₓ.

All NOₓ reduction strategies of these Fives North American (FNA) burners revolve around three basic principles:

  • Control of the maximum flame temperature
  • Reduction of oxygen concentration in the atmosphere
  • Reduction of residence time in the atmosphere

The LNI system uses all three techniques, resulting in extremely low NOₓ emission, even in high temperature air preheating applications.

How does it work?

The FNA system operates in the following way:

  • When the furnace temperature is below 1400°F (760°C), it functions as a low NOₓ nozzle-mixing burner.

  • Above 1400ºF (760°C), the fuel is switched to strategically located nozzles adjacent to the burner port.

  • The jets of fuel and air entrain large volumes of combustion products, greatly reducing local oxygen concentrations.

  • In the flame envelope, entrained gases limit the maximum in-flame reaction temperatures that generate high NOx emissions.

  • All combustion takes place within the furnace, not inside the tile port, providing short high temperature residence times that further inhibit NOₓ production.

  • After combustion, the gases lose their heat through radiation and convective heat transfer to the work; they travel through the furnace and are again entrained by jets of air and fuel, sustaining the NOₓ inhibiting process.


Benefits of HiRam LNI technology

Some of the many advantages and applications of this system are as follows:

  • Ultra low NOₓ emission, even with 100% oxygen

  • Significant fuel savings

  • Burner oxidant can be cold or preheated air, oxygen or a combination

  • Proprietary cooling design can eliminate the need to use cooling water

  • Able to fire in ratio or with high excess air

  • Accepts high temperature drying or curing cycles for any type of refractory

  • Its low pressure combustion air entails reduced power input

  • Heating is improved due to optimally dispersed hot gas radiation

  • High speed discharge improves convective heating



  • Steel reheating furnaces
  • Aluminum smelters
  • Forge furnaces
  • High temperature furnaces


Nutec Bickley is an authorized distributor of Fives North American in Mexico; we have combustion equipment and an expert team ready to assist you. Contact us now and tell us about your projects.

Advanced Firing & Heating Technology