Comparison of primary conversions from a flowing-solvent and a mini-bomb reactor: the effect of extended residence times of products in the reaction zone

Fundamentals of Coal Pyrolysis and Liquefaction

“…Detailed comparison of the liquefaction of the same sample of Point of Ayr coal in the flowing solvent reactor and in a minibomb reactor operated at the same temperature for the same duration of time (19) has demonstrated the success of the design of the flowing solvent reactor in minimising retrogressive reactions. When tetralin was used as the hydrogen donor solvent conversions in the flowing solvent and the minibomb reactors were found to be quite similar.…”

“…In the minibomb reactor at 450°C these reactions had a characteristic time of 10-100 seconds which increased to over 1600 seconds at 400°C. Not only was there insufficient time for these retrogressive reactions to develop in the flowing solvent reactor but, as reaction 4 predicts, the enhanced dilution of the products inherent in the design of the reactor decreases the rate of the retrogressive reactions even further (19). --,.…”

“…------;'Sio __ ., Table 9 -conditions with various peak temperatures (19). Tables 7 and 8 illustrate how yields of liquefaction products from maceral group concentrates vary with the temperature and the hold time in the flowing solvent reactor (20).…”

Analysis of Recovered Solvents from Coal Liquefaction in a Flowing-Solvent Reactor by SEC and UV-Fluorescence

“…However, the use of THF in SEC has been shown to promote adsorption of coal derived materials on the column packing, giving results not related to size exclusion, as well as being a poor solvent compared to NMP (Begon, 2002;Islas et al, 2002Islas et al, , 2003. In addition, the use of only one wavelength, 254 nm, tended to discriminate against the largest aromatic clusters observed in the THF insoluble materials (Gibbins, 1991;Herod et al, 1996;Zhang et al, 1997). Accordingly, no reasonable comparisons can be made with the previous work, except to reinforce the message that SEC in THF is no longer useful for coal-derived materials.…”

“…The main advantage of the FSR is that the formation of secondary reaction products is minimized because the reaction bed is swept by a continuous flow of fresh solvent. Previous work showed that the extract prepared in the FSR gave the largest molecular mass (MM) distribution compared to the ones obtained from the minibomb (MB) (Gibbins et al, 1991) and the pilot plant (PP). The extracts also had greater reactivity during hydrocracking, due to the release of fresh material from the coal, with minimal thermal degradation.…”