Feedstock Blending Studies With Laboratory Indirectly Heated Gasifiers

To support the further development of indirectly heated gasifiers, intended to provide fuels for advanced gas turbines, several laboratory indirectly heated gasifiers were constructed. During many comparative tests advantages and problems with each system were observed. The most useful systems make use of laboratory tube furnaces in conjunction with temperature, time and pressure or volume yield measuring systems and a gas chromatograph with a thermal conductivity detector. In this paper high temperature pyrolysis results obtained with the latest system are presented. Contrasting feedstocks suitable for commercial systems separately or in blends are used. Yield vs. time measurements are used to determine relevant rate constants and outputs. Since the rate constants are mainly reflective of heat transfer effects, cylindrical dowel sticks of varying radii were volatilized. The data set leads to an analytic heat transfer model that considers the hemicellulose, cellulose, and lignin components of the dowels. Also developed from the dowel experiments is an approximate procedure for estimating the proportionate releases of CO, CO₂, CH₄ and H₂ for any type of biomass whose component proportions are known.