Flame Rectification Study for Natural Gas-Hydrogen-AirMixtures in Industrial Premixed Burners

Premixed combustion of hydrogen/natural gas fuel mixtures was experimentally investigated to address the chal-

lenges of flame rectification and flame structure diagnostics. The industrial burner (i.e., PHOTON65 unit) was

operated at atmospheric pressure. The burner’s control unit maintained and stabilized combustion, while precise

fuel blends were achieved using mass flow controllers. Gradually, the natural gas content was reduced from 100%

to 0% by volume, while the hydrogen content was increased from 0% to 100%. Different fuel mixtures were

tested at a fixed airflow rate, while the fuel flow rate was varied to achieve a successful sustained flame on the

industrial burner’s bed. In burner applications, flame detection is achieved using sensors that detect the presence

of flame through an electric signal. This signal can be utilized by ignition and control systems. UV (ultra-violet)

phototubes exploit the ultra-violet radiation emitted by the flame, which is particularly suitable for applications in

enclosed industrial burners using gaseous fuels. This study employed a BRAHMA FD2 with a lateral view, and

peak detection was approximately 310 nm for flame rectification purposes. Various axial positions and angular

orientations were investigated to determine the optimal position of the UV sensor for hydrogen combustion flames.

Additionally, flame visibility, flame blow-off, and flame sustainability were investigated to identify the most suit-

able position for the UV sensor in all studied fuel blend cases. Flame height and structure undergo significant

changes with an increasing percentage of hydrogen in the fuel mixture. The UV sensor provides a cost-effective

and reliable solution for flame detection and rectification in space heating industrial burners.