Rapid pyrolysis

Zanzi, R., Sjostrom, K. and Bjornbom, E., Rapid Pyrolysis of Agricultural Residues at High Temperatures, submitted to Biomass Bioenergy, 2001... 

Table 4.3 Comparison of Slow and Rapid Pyrolysis Char Yield and Density at 800°C to 1000°C...

Slow Pyrolysis, Therombalance Rapid Pyrolysis, Free Fall Reactor ... 

High temperature degradation processes above 200°C include rapid pyrolysis of the wood components, combustion of flammable gases and tars, glowing of the char residue, and evolution of unburned gases, vapors, and smoke. 

Cannard and Criddle [195] have described a rapid pyrolysis-gas chromatography method for the simultaneous determination of Paraquat and Diquat in pond and river waters in amounts down to 0.00 lppm. 

Coal gasification can be considered to occur in two stages rapid pyrolysis followed by relatively slower heterogeneous reactions between the gaseous reactants and the remaining char. 

Models of wood pyrolysis and combustion have been developed to aid in fire safety and have treated various physical and chemical phenomena (3-9). Several studies have determined volatiles composition from rapid pyrolysis of small particles (10-13) However, few studies have combined modeling of heat transfer effects and detailed experimental resultsOJ). To our knowledge, no study has measured volatiles composition as a function of time from devolatilizing large particles of wood. 

Rapid pyrolysis is most pronounced in the CSD SRC and is predominantly responsible for achieving high overall solid conversion efficiencies despite the lower char reactivity of the CSD SRC relative to the PFD SRC. The ASD SRC exhibits a markedly lower pyrolysis rate than the other two SRC solids which renders it overall less reactive. 

Bio-oil from rapid pyrolysis is usually a dark brown, free-flowing liquid having a distinctive smoky odor. It has significantly different physical and chemical properties compared to the liquid from slow pyrolysis processes, which is more like a tar. Bio-oils are multicomponent mixtures comprised of different size molecules derived primarily from depolymerization and fragmentation reactions of the three key biomass building blocks cellulose, hemicellulose, and lignin. Therefore, the elemental composition of biooil resembles that of biomass rather than that of petroleum oils. Basic properties of biooils are shown in Table 33.7. More detail on fuel-related characteristics is provided in the literature.571... 

P.J.J. Tromp and J.A. Moulijn, Slow and Rapid pyrolysis of Coal, in Y. Juriim (Editor), New Trends in Coal Sciences, Kluwer Acad. Publ., Dordrecht, 1988, pp. 305-309. 

Role of Exchangeable Cations in the Rapid Pyrolysis of Lignites... 

M. Miura et al.. Rapid pyrolysis of wood block by microwave heating. Journal of Analytical and Applied Pyrolysis, 71, 187-199 (2004). 

Badzioch [I] summarized the volatile yields in the pioneering studies carried out at relatively low temperatures in a publication on rapid pyrolysis containing three introductory... 

It is essential to centralize the feed and keep it away from the reactor walls. Sticking of particles to the inner snrface of the walls tnms rapid pyrolysis into fixed-bed pyrolysis. The growth of the stnck mass leads to blocking of the reactor. Carbonization on walls is an impediment to drawing a mass balance. 

R. S. Torres and P. van Meurs, Laboratory studies of the rapid pyrolysis and desulfurization of Texas lignite. Fuel, 59, 458 (1980). 

A Comparison of the Rapid Pyrolysis of a Lignite and a Bituminous Coal... 

Zanzi, R., SJdstrom, K. BjOmbom, E. (1995). Rapid pyrolysis of agricultural residues at high temperature. Proceedings of the 2 Biomass Conference of he Americas Energy, Environment. Agriculture, pp. 630-636. 

Hajaiigol, MR J.B. Howard, JP Longwell, WA Peters (1982) Product Compositions and Kinetics for Rapid Pyrolysis of Cellulose, JndEng Chem. Res., 21, 457-465. 

Nunn, TR., J B. Howard, JP. Longwell, and WA. Peters (1985a) Product Compositions and Kinetics in the Rapid Pyrolysis of Sweet Gum Hardwood, Ind Eng. Chem. Process Des. Dev., 24, 836-844. 

There are several classes of compounds formed from rapid pyrolysis of carbohydrates. Besides anhydrosugars, they are carbonyl compounds, furan derivatives, lactones, pyran derivatives, phenols, acids and acid esters, and other compounds. In general, the presence of a substantial quantity of 5-hydroxymethylfuraldehyde in the pyrogram indicates that a hexose is present. Substantial amounts of furaldehyde and the absence of 5-hydroxymethylfuraldehyde in the pyrolysis products indicate the presence of a pentose. However, these markers are not diagnostic for a specific hexose or pentose. 

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