Issue 161-M

مجلة النفط والتعاون العربي

161

العدد

- 2017

أربعون

المجلد الثالث و ال

2016

أوابك العلمية لعام

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ص لبحوث العلمية الفائزة بجائزة

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عدد خا

The final step is fractionation to recover further gasoil and produce light and

heavy base stocks.

The yields are reported to be 7%water, 5% gasoil, 75% lube oils and 13% asphalt.

Many plants have been built by STP including three in Italy of total capacity 125

thousand tons a year, a plant in Canada of 60 thousand tons a year to produce

VGO and a similar plant in France for 120 thousand tons a year. The company

says that VGO is used as feed for further processing in a fluid catalytic cracking

unit (FCC) or a hydrocracking unit (HC)

The Dollbergen Process:

1, 24

Fig (14). This process belongs to a re-refinery in Germany (Mimeraol-raffineirie

Dollbergen) and was patented in 2004. It is based on distillation and solvent

extraction processes. After settling and filtration, potassium hydroxide solution

(KOH) is injected into the used oil stream to neutralize acids and help in the de-

metalizing of the oil. The used oil then enters a distillation column at near

atmospheric pressure and 140

C to remove water and light ends. The second step

is a vacuum column at bottom temperature of 260

C to recover “light heating

oil”

, diesel and gasoil, and the third step is a thin film evaporator working under

high vacuum (0.044 psi) and 385

C to separate a heavy bottom product. The

stream is then treated by N-methyl1-2-pyrrolidone (NMP) solvent in a solvent

extraction column to extract contaminants and finally to recover solvent and base

oil cuts by distillation.

The processors say that toxic components such as PNA and PCB if present in the

used oil are thereby removed. They claim that the solvent extraction process is

superior to hydrogenation in preserving components of synthetic base oil that may

be present in modern lubricating oils.

A second thin film evaporator under higher vacuum is used to treat the bottoms

of the first one to recover heavier base oil stock (not shown in the diagram). The

base oil yield depends on the solvent to feed ration and can range between 84 and

92%.

The capacity of the re-refinery using this process is 230 thousand tons a year.