The automatic fraction collector (in the system section TBP: with 20 receivers) includes a built-in internal balance for the determination of the fraction weight, while the separate volume follower system is used for discharging the fractions into the final receivers and the determination of the fraction volume as well as for the direct distillation rate control.
The automatic fraction collector (in the system section Potstill: with 12 receivers) includes a built-in internal balance, which is used for the simultaneous determination of the fraction weight and for the direct distillation rate control.
Summary of test method
On this unit, first TBP section is used where a crude oil sample between 1 and 30L is weighed, a debutanization process is made to remove gases and then distillation at several pressures (atmospheric, 100,5 and 2mmHg) is performed and fractions are collected as per analysis requirements up to 400°C AET in a column of up to 18 theoretical plates. A reflux of 5:1 is maintained at all times except at lower pressures. Mass and density of each fraction are obtained and based on these data yields are calculated. Finally, TPB curves of mass or volume% vs AET are drawn.
Once TBP is done, a measured and weighed residue from flask is placed on Potstill section and distilled at a low pressure between 50 and 0.1mmHg at at a specific distillation rate dependent on pressure. Fractions are taken at different temperatures as required by analysis. Mass of each fraction is obtained and yields by mass are calculated from the mass of each fraction. Density of each fraction is also obtained and yields by volume are calculated from volume of each fraction @ 15°C relative to total recovery.