Experimental laminar burning velocity of syngas from fixed-bed downdraft biomass gasifiers

Abstract

Laminar burning velocity is considered as being one of the fundamental properties of a premixed flame and reliable data are constantly required for practical applications. Although it is possible to find an extensive amount of experimental laminar burning velocity data for fuels containing one or two components, data for fuels with three or more components are scarce. The goal of this study is to help fill this gap by providing experimental laminar burning velocity data for a fuel mixture with five components (H2:CO:CO2:CH4:N2). The fuel composition utilized is proposed as surrogates of the fuel provided by a downdraft gasifier, the most common and the most efficient type of gasifier. Experimental measurements were carried out for different fuel-to-air equivalence ratios (0.88 < ϕ < 1.74) at atmospheric conditions, 954 mbar and 298 K. The method utilized was the conical-flame surface using OH PLIF images (Planar-Laser-Induced Fluorescence imaging of OH). The area method provides a good approximation of the unstretched laminar burning velocity. Experimental data were compared with the simulated results obtained from a CHEMKIN chemical kinetics software. The highest experimental laminar flame speed of a downdraft syngas air mixture was 0.3491 m s−1 and occurred when ϕ ∼1.3.