Low-NOx™ Calciner

Effective low NOx™ calciner designs reduce the thermal NOx generated in the kiln and limit the formation of fuel NOx in the calciner

Low-NOx Calciner
  • Overview

Proven technology for controlling NOx™ emission

The standard offering by FLSmidth for new and upgraded cement plant preheater installations includes the proven Low-NOx In-Line Calciner (ILC) system.

The design of the FLSmidth Low-NOx ILC system is based on the understanding of the basic chemical reactions which allow for NOx reduction. Numerous studies have been published showing the low-NOx capabilities of this design.

Key benefits

  • Effective emission control
  • Easy operation
  • Highly reliable
  • Optimised fuel and power consumption
  • Long refractory life
  • Excellent suitability to low grade fuels

How it works

The fuel is injected into the kiln riser below where the tertiary air enters at the base of the calciner. This so-called reduction zone, sized for a particular gas retention time, has an oxygen deficient atmosphere that promotes NOx reduction.

The optimum temperature in the zone is controlled by a material split from the second lowest stage between the calciner and the kiln riser. This material split is also used to control possible build-up within the kiln riser. Above the reduction zone is the main calciner vessel, which is divided into two or more sections separated by a notch. The changes in cross-sectional areas create turbulence that ensures effective mixing of fuel, raw meal and gas, improving heat transfer and combustion.

The calciner outlet loop duct ensures optimum gas retention time, further mixing and complete fuel combustion.

Optionally, the second- or third-lowest stage cyclone material can be further split to allow for diversion of a portion of the meal directly into the upper section of the calciner. This creates a “hot zone” in the lower section of the calciner that boosts the burning of difficult fuels and further NOx reduction.