Waste biomass distribution

Presuming the market for furfural and its derivatives ultimately grows to the point where commodity uses require the availability of large amounts of furfural, woody and waste biomass feedstocks can serve as a much more abundant and distributed source of supply than com cobs, oat hulls, and rice... 

The biomass is fed overbed through multiple feed chutes using air jets to help distribute the fuel over the surface of the bed. Variable-speed screw conveyors are usually used to meter the fuel feed rate and control steam output. Feedstocks such as bark and waste wood are chipped to a top size of 25 mm (1 in) to ensure complete combustion. The bed usually consists of sand around 1 m (3 ft) deep. This serves to retain the fuel in the furnace, extending its in-furnace residence time and increasing combustion efficiency. It also provides a heat sink to help maintain bed temperature during periods of fluctuating fuel moisture content. 

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. 

Although under certain experimental condition, step 2 or step 3 may be ignored due to its non-conspicuous influence to the flnal pyrolysis product distribution, however, a good mathematical model for biomass pyrolysis should be versatile applicable to other pyrolysis conditions, and thus it should be involved the above-mentioned three steps of process, of course heat and mass transfer equations should be included also. This paper presents this kind of mathematical model. Although the model is constructed based on sawdust pyrolysis, it is quite straightforward to apply the same approach to other cases such as straw and municipal solid waste pyrolysis even if to biomass or coal gasification or metal ore reduction. 

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