Fractionated pyrolysis

Technoeconomic Assessment. Although the use of fractionated pyrolysis oils as adhesives is still in the early phases of development, a technological assessment of the process was made using the best projections available for the yields and operating conditions. A detailed process flowsheet was made with mass and energy balances around each major piece of equipment. The equipment was sized and then valuated using data from the literature. The costs... 

An interesting experimental point in this investigation was that toluene from different sources purified by the usual methods of shaking with sulphuric acid, distillation and crystallization appeared to contain an impurity which gave erratic kinetic results for the pyrolysis. This impurity could be removed by fractional pyrolysis, and in all Szwarc s work the toluene was purified by twice repeated partial pyrolysis at 845° G, followed by distillation over sodium With this material reproducible kinetic results were obtained. 

Fractionated pyrolysis A pyrolysis in which the sample is pyrolysed at different temperatures for different times in order to study special fractions of the sample. 

F g. Product distribution following fractional pyrolysis (wt. %, anhydrous wood basis). 

The maximum phenolic compounds which could be produced and identified was about 2.5 wt. % on an anhydrous feedstock basis during the one-step pyrolysis approach in the temperature range of 25-550 C. Interestingly, 4.4 wt, % phenols were identified following the fractional pyrolysis approach in a lower temperature range of 25-450 C. One can conclude that the removal of volatile phenols during the fractional approach prevents some secondary thermal decomposition reactions which occur during the one-... 

Commonly, analytical pyrolysis is performed as flash pyrolysis. This is defined as a pyrolysis that is carried out with a fast rate of temperature increase, of the order of 10,000° K/s. After the final pyrolysis temperature is attained, the temperature is maintained essentially constant (isothermal pyrolysis). Special types of analytical pyrolysis are also known. One example is fractionated pyrolysis in which the same sample is pyrolysed at different temperatures for different times in order to study special fractions of the sample. Another special type is stepwise pyrolysis in which the sample temperature is raised stepwise and the pyrolysis products are analyzed between each step. Temperature-programmed pyrolysis in which the sample is heated at a controlled rate within a temperature range is another special type. 

Vacuum Pistillate Fractions. Pyrolysis of the saturate fraction for 30 minutes at 450°C gave the n-alkane and 1-alkene product distribution shown in Figure 3. This same data in tabulated form is compared in Table I with the starting material. The comparison indicates a net loss in concentration for the n-alkanes C16 and larger and a net gain for those with 14 or less carbons. The 1-alkenes exhibit a similar relationship with carbon number. For this pyrolysis time, the yield of small... 

The potential n-alkane yield for the saturate fraction decreases as pyrolysis time increases. On the other hand, the n-alkane yields go through a maximum with time for the aromatic and polar residual fractions. Pyrolysis times in excess of 60 minutes are preferred with respect to lower potential n-alkane yield but this would be at some loss in JP-5 yield. 

Dandik, L., Aksoy, H.A., 1998. Pyrolysis of used sunflower oil in the presence of sodium carbonate by using fractionating pyrolysis reactor. Fuel Processing Technology 57 (2), 81-92. 

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