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Aerospace - NOx Burner Retrofit Program

Business Objective

An aerospace manufacturing facility committed significant resources to retrofit two existing ovens with “low NOx” burner technology, this retrofit was done to ensure the ovens’ NOx emissions complied with the local air district’s new nitrogen oxide (NOx) standard. However, following the installation of the low-NOx burners, NOx emissions from the ovens were observed at levels in excess of the District’s new NOx standard. The facility’s environmental and plant management staff, frustrated with the NOx testing results, contemplated a complete replacement of these ovens. To complicate matters, as the facility was resolving this issue internally the local air district performed a site inspection, during which the facility was issued a Notice to Comply (NTC) that directed the facility to demonstrate compliance with the new NOx standard through a source test. Frustrated and fearing aggressive enforcement, the facility contacted ALG for our expertise to resolve these issues on a compressed schedule.

Technical Approach

ALG staff relied on familiarity of standard combustion principles and air pollution emissions to assess a potential root cause for the observed elevated NOx emissions. From this analysis, ALG developed a strategy that involved tuning of oven burners and an optimized operating regime to reduce NOx emissions. ALG then worked with the District to obtain additional time to allow for these installation/burner settings to be further refined, and for source testing to be performed to demonstrate compliance with NOx limits. To implement the suggested strategy, ALG coordinated with the burner manufacturer’s technical staff to arrange appropriate tuning/adjustments of the ovens and worked with source testing contractors to obtain the approval from the local air district of a testing protocol consistent with ALG’s suggested oven operating regime. Throughout this phase of the project, ALG staff was in routine communication with District engineering and enforcement staff, and obtained additional extensions of the Notice to Comply. ALG then worked on-site to coordinate with facility staff, equipment vendors and source testing contractors during the performance of the source test to ensure proper implementation of the test plan and recommended operating regime.


These comprehensive programs allowed our client to demonstrate compliance with District’s NOx emissions limits thereby avoiding a costly replacement of the two ovens. This was done in such a way as to ensure District compliance staff was satisfied, and avoided the issuance of any notice of violation (NOV) or penalties.

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