Physical characteristics of biomass and its influence in sel-combustion

The necessity to find new sources to produce a cleaner energy, reducing the CO2 emissions, leads to consider biomass as a potential sustainable feedstock to be used instead of coal in power plants. Biomass and coal present significant differences in terms of both chemical composition and physical properties. Biomass usually has an increased thermal sensitivity and a greater ease of ignition. Also, biomass particles commonly have more irregular shapes and larger sizes than pulverized coal, thus it is necessary to establish the parameters of these materials to avoid the self-combustion tendency. In the same way than coal, biomass stored are potentially able to absorb oxygen to produce exothermic oxidation reactions. If the generated heat in these reactions is not properly dispersed, causes a self-heating of the organic matter that can cause breakdown and ignition. In the field of possible self-combustion in the storage and handling of the biomass there are several factors which have influence in biomass thermal susceptibility, i.e. its tendency to oxidation and subsequent ignition of the substance. In this respect, the different biomass analysis to determine their behavior is shown here. This study has been developed using biomass obtained from agriculture, forestry, olive oil waste and aromatic plant waste. Those products have different chemical composition and it could imply different behavior. Samples tested have been prepared by different physical processes to assess the influence of different factors in their self-combustion. All products tested are commercial products available in the market for potential use in gasification plants. Methods employed were based on classical techniques of thermogravimetry, differential scanning calorimetry, analysis of composition and physical analysis as shape factor and particle size distribution. Methodologies used in the thermal analysis are not standard tests, but that are based on a long experience in the application of these techniques to coals and other products. In order to compare results, test widely used in previous research works has been carried out to define the characteristic parameters of the experimental methodology