Biomass Combustion Characteristics and Implications for Renewable Energy

摘要: Unlike pulverized coal, biomass particles are neither small enough to neglect internal temperature gradients nor equant model as spheres. Experimental and theoretical investigations indicate particle shape size influence dynamics, including essentially all aspects of combustion such drying, heating, reaction. This chapter theoretically experimentally illustrates how these effects impact conversion. samples include disc/flake-like, cylindrical/cylinder-like, (nearly spherical) shapes wood with similar masses volumes but different surface areas. Small (320 μm) passed through a laboratory entrained-flow reactor in nitrogen atmosphere maximum wall 1,600 K. Large were suspended the center single-particle reactor. data that react more slowly than other shapes, difference becoming significant mass or aspect ratio increases reaching factor two for sizes over 10 mm. A one-dimensional, time-dependent simulates rapid pyrolysis process shapes. The characterizes three basic (sphere, cylinder, flat plate). With geometric information (particle ratio, volume, area) included, this devolatilization any shape. Model simulations show satisfactory agreement experimental data. predictions both affect product yield distribution. Near-spherical exhibit lower volatile higher tar yields relative aspherical same under conditions. Volatile decrease increasing Assuming spherical isothermal conditions leads large errors at most practical interest.