The ART Process is used for solvent dewaxing of vacuum gas oils to produce low pour point lube base oils and for de-oiling waxy feedstocks to produce waxes with a low oil content.

Developed and patented by Advanced Refining Technologies, Inc. (ART), a wholly-owned BATEMAN subsidiary, the process has several processing advantages. The low solvent charge reduces the size of the equipment and the energy for solvent recovery. The high filtration temperatures, in combination with the lower solvent charge, reduce the refrigeration requirements, while the crystallisation mechanism eliminates the need for scraped-surface heat exchangers which are costly and difficult to maintain.

Studies of commercial designs for a range of capacities, feedstocks and solvent selections show capital- and operating-cost savings ranging from 20 % to 40 %, depending on the application, compared to a conventional methyl ethyl ketone (MEK) / toluene facility. A detailed study for a 5 000-bpd de-oiling unit estimated capital-cost savings to be in the range of 30 % and operating-cost savings around 50 %. The process also shows significant advantages over MIBK (methyl isobutyl ketone) based schemes for de- oiling applications.

Pilot-plant studies have been conducted on a 40 litre/h unit, fully equipped with the required crystallisation, vacuum filtration and solvent-recovery units needed for continuous operation. It was operated for two years (1992 -1994) on a variety of feedstocks and then superseded by a semi-continuous pilot plant to establish the process parameters required for the design of a commercial plant. The first licence for a commercial ART Process plant was sold in 2000.

The process employs different solvents from the conventional MEK / toluene based processes and utilises them in a unique fashion. Specifically, the solvent and co-solvent are added to the oil separately instead of as a mixture and this results in wax crystallisation based on equilibrium solubility rather than relying on refrigeration and scraped-surface heat exchange. This method permits the use of different solvent sets that have been demonstrated, on most feedstocks, to require lower solvent charges and higher crystallisation temperatures than conventional processes for a given processing objective. For example, it has been shown that in dewaxing applications, filtration temperatures are generally at least 2 to 5° C higher than the resulting pour point of the oil, compared with 3 to 10° C lower when conventional technology is used.

A fundamentally different crystallisation mechanism is used by the ART Process which results in better filtration characteristics on many feedstocks. This, combined with the higher operating temperatures, often improves filtration rates.

The ART Process also offers several choices for the selection of the solvent pair. These are commercially available substances and in some cases have better environmental characteristics than MEK and/or toluene.

More information may be obtained from Bill Howe, Executive Director, BATEMAN Oil, Gas & Water, on +27-11-899-3285 or email whowe@batepro.co.za

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