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أوابك العلمية لعام
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ص لبحوث العلمية الفائزة بجائزة
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عدد خا
مجلة النفط والتعاون العربي
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العدد
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أربعون
المجلد الثالث و ال
Re-refining of Used Lubricating Oil and its Economic and Environmental Implications
43
4.18 MRD Technology
The technology based on liquid-liquid extraction was developed by Mineralol-
Raffinerie-Dollbergen (MRD) in the mid-1990s. It is claimed to be one of the latest
solvent extraction processes.
4.18.1
Process description
The MRD process consists of the following steps:
Dewatering stage:
Atmospheric distillation is used for separating water and low-boiling fractions
Vacuum distillation and thin film evaporation:
The extract recovery section also consists of a distillation and a stripping column. Pre-
treated oil is vacuum-distillated with production of a gas oil fraction. Then it is sent to a
special extraction column, where base oil fraction is separated from the extract by
specific solvent(N-Methyl Pyrrolidone), which allows quantitative removing of PAH
and preservation of the positive impact of low temperature viscosity behavior of these
groups of oils.
Solvent Recovery:
The humid solvent separated in the stripping columns of the Raffinate and Extract
recovery sections is returned to the solvent drying column, where excess water is
removed. The ‘dry’ solvent is also returned to the solvent tank. From there, the dry
solvent can again be used for extraction purposes in the extraction column.
4.18.2
Process features and drawbacks
The MRD solvent extraction process is considered the latest development for refining
vacuum distillates from used oils. It is claimed that the novel process developed by
MRD completely satisfies the requirements existing for a modern technology for
producing from used oils high-quality base oils, the properties of which in some
respects are even superior to those of the classical solvent raffinates produced from
petroleum.
A plant is operating near Hanover, in Germany. The re-refinery has a capacity allowing
it to process 230,000 MTPY of used oil and oil-containing liquids. 120,000 MTPY thereof
are used as feedstock for the production of 70,000 MTPY of new base oils.