The
building of a separation-reaction network for heavy feedstock
requires an understanding of the reactivity for subfractions. This
paper proposes a study on the coking reactivity for two heavy petroleum
samples, vacuum residua (VR) from China Liaohe and Venezuela Orinoco
crude oils, and their supercritical fluid extraction fractionation
(SFEF) subfractions. The properties of feedstocks and their SFEF series
were analyzed, including density, molecular weight, elemental content,
Conradson carbon residue (CCR), SARA components (saturates, aromatics,
resins and asphaltenes) and structure parameters by nuclear magnetic
resonance (NMR). All the samples were subjected to a laboratory-scale
batch reactor to investigate the coking reactivity. Coke yield increased
as the SFEF subfraction became heavier; while the yields of naphtha,
diesel, and gas oil all decreased. The results show that the classic
linear correlation between coke yield and CCR are not appropriate
for separated fractions of VR. Instead, a negative power function
was observed. Furthermore, the coke yield shows a linear relationship
with aromaticity for both SFEF series. To precisely estimate coking
reactivity for feedstocks and subfractions, a new SARA component based
prediction model was carried out, which reveals the contribution of
each component.
Factors affecting microwave-assisted extraction of garlic essential oil from garlic were investigated experimentally. Suitable conditions for such extraction process were studied by single factor approach to improve the product yield. The product yield under the resultant suitable conditions can reach to 0.478% based on raw garlic cloves. The product yield for microwave-assisted extraction method is as 2.5 times as that for conventional solvent extraction approach.
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