Char available energy

Figure 1. Percent available energy in char-oil mixture composite of all data...

These reactions show that incomplete oxidation of the char to CO produces about 25% of the total energy based on the available carbon and 50% of the total energy based on the available oxygen. Because the oxidation reactions are activated and exothermic, when... 

The main problem, however, with biomass as it is available now is that at an industrial scale, most current energy conversion equipment is designed to operate on fossil fuels and at a domestic scale, most if not all stoves are for wood or charcoal use and will not operate properly on these residues. Thus there is a need for a means for converting residues into synthetic coal, oil and gas which could be utilized in existing equipment. Pyrolysis, especially low temperature pyrolysis, which favors char and oil production, offers a particularly promising means of conversion, since the char and oil products are storable and easily transportable-an especially attractive characteristic in developing countries. 

Reaction of steam with carbon is one of the basic processes involved in the gasification of coals or chars to produce clean fuels. The industrial importance of this reaction is considerable, particularly at this time of spiraling energy costs. In addition, the steam-carbon reaction finds other important industrial applications, such as preventing or minimizing the coking of olefin-plant cracker-tubes. Because of its commercial importance, the steam-carbon reaction has been studied extensively, and excellent reviews are available (1,2). In addition to reaction kinetics and mechanisms, the effects of carbon structure, catalysis by metals, and impurities (anions) have been investigated (3,4, .5) ... 

Errors (/>(calc)-/ (expt)) in the relaxed crystal structures using a fixed repulsion-dispersion potential (as in Table 11.2) and various electrostatic models derived from a DMA of a 6-31G SCF wave function DMA, full multipoles up to hexadecapole SDMA, all multipoles scaled by 0.9 CHAR, just the charge component of the DMA. The r.m.s. % errors were calculated over the three cell lengths. The electrostatic contribution, (7estat, to the total lattice energy, Us, is given at both the experimental (for the SDMA model) and relaxed crystal structures. This can be compared with the experimental heat of sublimation Af/sutl (Chickos 1987), where available. 

Gasification and pyrolysis are the thermal conversion processes available for the thermal treatment of solid wastes. As shown in Figure 8.3, different by-products are produced from the application of these processes and different energy and matter recovery systems can be used to treat these products [16, 27]. Both pyrolysis and gasification produce three different phases a solid phase (char, 5-25 wt%), liquid phase (tars, 10-45 wt%) and gas phase [14, 22, 28]. The main disadvantages of plastic pyrolysis and gasification are the necessity to control the chloride content in the feedstock and the risk of bad fluidisation because of particle agglomeration [29]. 

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