157 / 222
150
2016
أوابك العلمية لعام
�
ص لبحوث العلمية الفائزة بجائزة
�
عدد خا
مجلة النفط والتعاون العربي
161
العدد
- 2017
أربعون
المجلد الثالث و ال
Re-refining of Used Lubricating Oil and its Economic and Environmental Implications
27
4.7.1 Process description
The basic steps of the process are:
Lights removal:
In this first step the waste oils are treated and light hydrocarbons are separated in flash
drum. The residue is sent to a vacuum tower.
Vacuum distillation:
In this step asphalthenes and other impurities are separated from the oil and different
viscosity grade oils can be produced. The base oil fraction is delivered to a liquid-liquid
extraction column after it is cooled.
Solvent extraction:
The treated base oil fraction is extracted with n-methyl-2-pyrrolidone, where
unsaturated, aromatic and heteroatom containing molecules are eliminated.
Unsaturated, aromatic and heteroatom containing compounds are in extract phase; the
base oil forms the raffinate phase.
The solvent is separated from the extract and returned
to the process after being
reprocessed from both of the abovementioned products with
stripping. The extract phase contains up to 10% base oil fraction as a function of process
parameters.
The process flow diagram is depicted in Figure 14.
4.7.2
Process features and drawbacks
Probex offers the following advantages: no use of high temperature and pressure, no
use of hydrogen, no catalyst handling and replacement. It is claimed that the yields are
comparable to hydrofinishing processes.