Investigation on a vacuum residue from Kirkuk

The vacuum residue from Kirkuk was characterized by elemental analysis, average molecular weight (vapor pressure osmometry), viscosity, density, asphaltenes content, and the usual index numbers of thermogravimetry (table 4-123)  

The quality of the heavy oil produced bears a direct relation to the addition of hydrogen during the hydrocracking reaction. The hydrogen addition (wt%) was calculated according to equation 4-1  

The results of the element analysis and the average molecular weight of the heavy oil produced, as well as the consumption of hydrogen in relation to the selected reaction parameters are listed in Table 4-124. The results of thermogravimetry of the heavy oils produced is shown in Table 4-125. 

On the other hand a drastic decrease of AG400 occur at reaction temperature 455 °C, when the residence time is 30 minutes, whereas an increase of T5 % starts at 60 minutes residence time. An explanation might be that, at a certain residence time, naphtha starts to form from the heavy oils, since there is a limited quantity of compounds within the vacuum residues which can be hydrogenated. This assumption is corroborated by the constancy of 

Vaporization Start Temperature T5 % of the Heavy Oil Fraction versus Residence Time 

---