Physical conversion moisture content

Uncertainties with the availability and suitability of biomass resources for energy production are primarily due to their varying moisture content, and to a lesser degree to their chemical composition and heating value. As the moisture content of biomass increases, the efficiency of thermal conversion process decreases. At some point more energy may have to be expended to dry the biomass than it contains. Uncertainties can be reduced by conducting a detailed chemical and physical analysis of the biomass sources. 

Thermal conversion of biomass/waste streams in oses demands on the fuel quality. The basic physical properties of the biomass and waste streams, such as moisture content, ash content and melting temperature, particle size (distribution), density and calorific value are irrqioitant properties, which determine the design specifications of a new installation to a large extent, The fact that biomass and waste Streams are usually til defined, leads to a significant spread in physical and chemical data. 

The coal or carbon conversion in a gasification process is governed by complex mechanisms that are dependent on the quahty of the coal used (coal structure or rank, particle size, evolving pore structure, catalytic effects of char minerals content, changes in surfece area, char fi acturing, and coal moisture) and the physical and chemical conditions around the particle (temperature, pressure, concentration of reactants such as O2, H2O, CO2, H2 and their diffusion properties). Because of these numerous influences, a theoretical prediction of coal reactivity is nearly impossible without laboratory data [4]. One important aspect of heterogeneous reactions is whether rate is controlled by diffusion limitations in the boundary layer around the particle, so-called bulk surface diffusion, or by diffusion inside the pores of the particle. 

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