Effect of oxygen enrichment of Biogas-Hydrogen mixtures in a premixed combustor on the combustion instability and emissions

© 2023 Elsevier LtdThe effect of enrichment of a low calorific (50 % CH4-50 % CO2) biogas mixture with hydrogen and oxygen has been investigated on combustion stability and exhaust emissions in a premixed burner. The thermal power was kept constant at 5 kW, the equivalence ratio of 0.8, and a swirl generator (1) was placed at the burner outlet. Initially, hydrogen (H2) was added to the biogas at intervals of 10 % up to 40 % by volume. The addition of hydrogen to the biogas increased the heating value of the mixture and reduced the instabilities. It has been determined that biogas/hydrogen mixtures containing 20 % and 30 % H2 showed the lowest combustion instability and pollutant emissions. It has been observed that with the addition of 30 % hydrogen to the biogas, the CO emission value, which was 5532 ppm, decreased to 130 ppm. Also, 23 % and 25 % O2 enrichment were applied to fuel mixtures. It was observed that combustion instabilities increased with oxygen enrichment in both fuel mixtures and flashbacks occurred under acoustic perturbation. It has been determined that the mixture containing 20 % H2 as the flame, which has the lowest emission and is resistant to acoustic perturbation, is burned at the 23 % O2 ratio by volume