Detection and control of H2–CH4 flames via ionization, thermal conductivity, and flow measurements

The integration of hydrogen into natural gas combustion systems requires reliable and cost-effective diagnostic tools to ensure safe and efficient operation. This study investigates flame ionization detectors (FID) and thermal conductivity detectors (TCD) for monitoring and controlling H 2 /CH 4 combustion. Results show that the optimal FID electrode position shifts toward the flame core with increasing hydrogen content and depends on burner design. FID provides robust detection of hydrogen-rich flames, with measurable signals up to 95% H 2 . Flame stoichiometry correlates with the ionization current scaled by burning power at a fixed H 2 /CH 4 ratio. These correlations must be empirically determined for specific burner–electrode setups. TCD quantifies the H 2 /CH 4 ratio accurately from 0% to 100%. A combustion control loop integrating FID, TCD, and flow transmitters and controllers is proposed, enabling reliable and low-cost adaptation of combustion systems to hydrogen-enriched fuels.