A comprehensive study on laminar burning velocity and flame stability of oxy-producer gas mixtures. Part-1: Gas mixture composition and flame stability analysis based on Lewis number

•Composition variation analysis of 800 actual producer gas (PG) mixtures.•Effects of combined variation of (CO2 + N2) and (CH4 + H2 + CO) on combustion.•Study of Laminar Burning Velocity, Markstein Length, Zeldovich and Lewis number.•Producer gas with high H2, CO, N2 & Low CH4, CO2 remain stable to mixture fluctuation.•LBV of above PG is less sensitive to mixture fluctuations & also predictable. The objective was to understand the effect of change in the composition of combustible (CC)/ non-combustible components (NCC) on the unstretched laminar burning velocity (LBV), burned gas Markstein length (Lb) and Lewis number (Le) of premixed producer gas (PG)-oxygen mixtures. Design of composition and flame stability aspects based on Le are presented in part-1. PG comprised of CC(CH4:CO:H2) + NCC(CO2:N2) and the extent of variation was identified from 800 compositions reported in 123 research works. In this work, forty-five PG mixtures were studied where CC:NCC varied from 25:75–45:55, CO2:N2 from 0:100–100:0 and CH4:CO:H2 from 25:25:50–50:25:25. Spherical flame method was used to measure the LBV at 1 bar, 300 K and ϕ = 0.8 in a 4.5L spherical chamber. Validation experiments were performed with (50%H2 + 50%CO)-air mixtures and it compared well with the literature and computational data. Unstable mixtures identified by effective (volume-based model) and critical Lewis numbers corroborated well with the experimental burned gas Markstein length.