How inerting systems work

Preventing or getting a fire under control can be achieved by replacing the oxidant with an inert gas. See how the process works.

Controlling the fire triangle and explosion pentagon

Fire triangle

For a fire to occur, three elements of the fire triangle must be present:

  1. Fuel (gas, dust...)
  2. The oxidant (oxygen in air)
  3. The activator (heat or ignition source)

Explosion pentagon

For an explosion to occur a fourth and fifth element must also be present:

  • A confinement (mill, filter, silo)
  • An ignitable dust cloud

The fuel and the activator cannot be removed from the equation, but the oxidant. That is the principle that Yara’s inert gas injection systems are based on – removing the oxidant.

Inert gases have a low level of reactivity. By replacing the oxidant they reduce oxygen levels to below critical concentration thresholds. The use of inert gases can prevent the ignition of dusts, gases or vapours and prevent oxidation and moisture absorption of certain sensitive products.

Which gases can be used in inert systems?

A range of different Inert gases listed can be used in Yara inerting processes:

  • Carbon Dioxide
  • Steam
  • Flue Gas
  • Nitrogen
  • Noble gases

Combustion gases and / or steam can be used in most applications, but are not available in the start-up and shutdown phases of industrial facilities. In practice, carbon dioxide (CO₂) and nitrogen (N₂) are most often used. Liquid CO₂ is often recommended for discontinuous emergency inerting (storage without losses) whereas Liquid N₂ is preferred for continuous inerting.

Yara's fire prevention and explosion prevention inerting technology is based on the precisely controlled injection of inert gases such as carbon dioxide (CO₂) and nitrogen (N₂).

How does inerting work in practice?

As an example, during the normal operation of e.g. a coal grinding workshop, inerting is naturally provided by the combustion gases from the kiln. In the event of a technical problem or during start-up or shutdown, the coal mill will be free of inert gases.

It is in these cases that Yara offers an additional source of reliable inert gas to keep your industrial installation and its employees safe.

Achim Rott
Achim Rott
Head of Sales Inerting, Cement & Lime