Pyrolysis fast flow

Meadows GW, Kirkland JJ (1952) Low pressure, fast flow pyrolysis of methylamines. J Phys Chem 65 2139-2143... 

Fast flow pyrolysis s. Pyrolysis, fast flow... 

Another difficulty has to do with industrial flow reactions. Pyrolysis is an endothermic reaction. In a fast flow system, the reaction can become nearly adiabatic, and consequently temperature drops of 100 or more degrees can occur. This means that heat transfer equations must be introduced into the kinetic scheme. These must be done in oversimplified (i.e.y one-dimensional) form, or the model can become intractable even on a large computer. 

Diebold, J. P. Scahill, J. W. Evans, R. J. Entrained-Flow, Fast Ablative Pyrolysis of Biomass. Annual Report 1 December 1984-31 December 1985, 1986, Solar Energy Research Institute, Golden, Cd. SEftT/PR-234-3012. 

Details on the preparation of pyrolysis oils at SERI in the entrained-flow, fast ablative pyrolysis reactor can be found in a report by Diebold and Scahill (2). The oils in Figure 1 were obtained from two runs, 40 (c and d) and 41 (a and b), the oils being collected from a packed scrubber (a and c) and a cyclone scrubber (b and d). The oil obtained from the packed scrubber in run 41 was subjected to sequential elution by solvents chromatography (SESC) according to the method of Davis et al (7). The HPSEC of fractions 1 through 6 appear in Figure 3. Fraction 1 was eluted with 15% toluene in hexane (yield 0.4%), Fraction 2 was eluted with chloroform (yield 1.5%), Fraction 3 was eluted with 7.5% ether in chloroform (yield 7.5%), Fraction 4 was eluted with 5% ethanol in ether (yield 19.5%), Fraction 5 was eluted with methanol (yield 38.1%), and Fraction 6 was eluted with 4% ethanol in THF (yield 3.1%). The oils displayed in Figures 4 and 5 were produced from run 66. 

CHjCHS The properties of monomeric thioaldehydes have been difficult to determine, because under normal experimental conditions they polynKri into cyclic dimers and trimers. Kroto and Landsberg were able to produce monomeric thioacetaldehyde as a product from the pyrolysis of 1,3,5-trimethyl-s-trithiane. The species is unstable, and was generated and detected in a fast flow systeni. The various species which coexist in this system at low pressures are summarized in Fig. 18. 

Gercel, H.F. 2002. The effect of a sweeping gas flow rate on the fast pyrolysis of biomass. Energy Sources 24 633-642. 

The desired primary liquid products of biomass pyrolysis react readily in secondary cracking reactions, shifting the product yield from liquids to gases. Those cracking reactions are assisted by contact of the volatiles to the remaining solids, which can be reduced significantly by running the fast pyrolysis in a reaction cyclone [79, 80]. A simplified flow sheet of such a laboratory plant for the fast pyrolysis of biomass is shown in Fig. 15.9. 

The experimental system used to carry out this work is a bench-scale installation based on Waterloo Fast Pyrolysis Process (WFPP) technology (19,20). The biomass feeder supplies a continuous biomass flow rate of between 5 and 100 g/h. Thermal decomposition of biomass occurs in a fluidized bed reactor with an inner section of 4.35 cm. ... 

Entrained flow fast pyrolysis was developed at Georgia Tech Research Institute (25) and scaled up by Egemin (26), Further details are available in (14). Neither the GTRI nor Egemin process is now operational and there are no known plans for further development, probably because of the difficulties that have been encountered in achieving good heat transfer from a gaseous heat carrier to solid biomass. Liquid yields of 50-60%wt. on dry feed have been obtained. 

This study was primarily focused on the volatility of tars that were prepared under conditions that minimize the extent of secondary reactions. Tars were produced using a fast pyrolysis technique (heating rate greater than 5 °C/sec). About 2 or 3 grams of sample on a wire mesh holder was pushed into the pre-heated tubular pyrolysis reactor. The sample temperature was measured by a thermocouple and the holder was pulled out from the heated region after the sample reached desired temperature. The final temperature was selected based on thermogravinietrig experiments at heating rate of 20 °C /min for each material studied and arc shown in Table 1. The inert gas (N ) flow was 300 ml/min at room temperature. That corresponds to the gas phase tar maximum... 

Entrainment and important fluidised bed parameters were measured for a I l /h and a 5 kg/h fast pyrolysis reactor. In addition, a cold-flow model of the Ikg/h rig was built to study fluidisation aspects that were difficult to obtain from the pyrolysis reactor. The cold-flow model was subsequently modified to validate the model s capability to deal with changes in the reactor geometry. The cold flow rig is illustrated in Figure 1. 

Figure 3 A schematic flow diagram of the proposed 2 t/hr fast pyrolysis system...

---