Over Fired Air

Overfire air (OFA) is a technique used in utility boilers to reduce emissions of nitrogen oxides (NOx) by injecting additional air above the primary burner zone in the furnace. The additional air helps to lower the peak flame temperature and create a more uniform temperature profile, which reduces the formation of NOx.

OFA can be effective in reducing NOx emissions, but it can also have several potential impacts on the operation of the boiler. One potential issue is that it can lead to increased flue gas temperatures, which can affect the performance of the boiler’s heat transfer surfaces and reduce efficiency. Additionally, the increased air flow can increase the pressure drop through the furnace and reduce the system’s capacity.

To mitigate these potential issues, it is important to carefully design and optimize the OFA system, taking into account factors such as the burner design, fuel characteristics, and operating conditions. The system should also be regularly monitored and adjusted to ensure that it is operating properly and not negatively impacting the performance of the boiler.

Overall, OFA can be a useful tool for reducing emissions from utility boilers, but it requires careful attention to design, operation, and maintenance in order to ensure that it is effective and does not negatively impact the performance of the system.