Comparisons in Biomass and Refuse Derived Fuel Pyrolysis. Multivarate Analysis Applied to an Experimental Design

At the University of Washington, biomass devolatilization or pyrolysis has been studied from a fundamental perspective by analysis of single reacting macroparticles. Despite the steep temperature gradients inside macroparticles, large chips will likely be used in industrial processes for economic reasons owing to the high cost of biomass size reduction. To investigate particle size as well as other effects, numerous experiments have been made on actual and fabricated wood as well as densified refuse-derived fuel macroparticles under well-controlled, realistic pyrolysis conditions of industrial importance. A large number of quantitative measurements have been made on each devolatilizing macroparticle. These include: devolatilization product compositions (overall product fractions and detailed chemical species) as functions of time, internal particle temperature histories, as well as infra-red spectroscopy and surface area of the char residues. However, many of the reaction products and observables appear to vary together, in other words, they are highly correlated over a wide range of experimental conditions. In a previous paper, we examined the product slate correlation for wood devolatilization. In this paper, we explore the similarities and differences between biomass and municipal solid waste devolatilization of thermally thick particles. The large data base, obtained in the same experimental apparatus using the principles of statistical experimental design, now permits us to see if some devolatilization products are “surrogates” for others. By this we mean, can only a few gas or tar species be measured and be predictive of nearly the entire composition matrix? This paper presents preliminary efforts in this direction.