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Pulse Combustion Technology: Achieving Low Nitrogen Oxide Emissions

Most governments globally agree that global warming is a reality and that something needs to be done about it. As such, there has been an increased interest in using renewable forms of energy, commonly referred to as cleaner energy. However, even with clean energy, there can be emissions of harmful gases into the atmosphere, such as nitrogen oxide. In order to maintain compliance with legislature, and protect the environment, gas turbine manufacturers have been working on reducing emission from their products leading to the development of two important designs:

nitrogen oxide

Lean-burn design
This revolutionary design has a halving effect of the amount of nitrogen oxide produced by gas turbines. In addition, the design has ensured increased efficiency and power for the same amount of fuel used.

How does it work?
Unlike regular gas engines that require a spark plug to initiate combustion, the lean-burn engines facilitate a prior mixing of air and fuel before entering the cylinder for combustion. In order to ensure a proper ratio of air and fuel (also referred to as a lean ratio), and accurate ignition times, there needs to be constant monitoring. This is done using a computerized controller to avoid error.

These mechanisms offer two major advantages:

  • Richer mixtures of air and fuel can cause engine knocking and high nitrogen oxide emissions. Alternatively, a very lean mixture can cause misfiring and raise hydrocarbon emissions. The lean ratio provided by this design keeps the engine from misfiring or knocking, while reducing emissions of both nitrogen oxide and hydrocarbons.
  • Engine design improves combustion by ensuring the air and fuel mixture is effectively exposed to the flame front, resulting in improved fuel efficiency with higher power output.

Dry Low NOx System
Similar to the lean-burn design, the main mechanisms of the dry low NOx design is to use a lower ratio of air and fuel in order to reduce emissions.

How does it work?
The dry low NOx system is a staged combustion mechanism consisting of four main modes:

  • Primary Mode
  • Lean-lean Mode
  • Secondary (Transfer) Mode
  • Premixed Mode

With all these modes, the lean air/fuel mixture is used to ensure maximum fuel efficiency and production of maximum power. For instance, in the transfer mode, the air/fuel mixture goes through a thorough combustion process. If flames are not detected in the primary zone of the mechanism, fuel is added in the primary zone and reduced in the secondary zone, being careful to maintain the lean mixture. The mixture then proceeds to the secondary zone for ignition and combustion. All this works towards extremely low nitrogen oxide emission and improved fuel efficiency. Stay tuned for our blog updates!