Publication Date: 2012-Sep-15
The IP.com Prior Art Database
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Carl Pei-Chl Chang
James R. Murphy
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TABLE OF CONTENTS
Deasphalted Oil and Solvent Asphalt Process Applications
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Processing of crude normally involves separation into various fractions
which require further processing in order to produce marketable products. The initial separation process is distillation, which separates crude into increasing- ly higher boiling range fractions. Since petroleum fractions are subjective to thermal degradation, there is a limitation to the temperatures that can he used
in simple separation processes. The crude cannot he subjected to temperatures
much above 100°/w~hout encountering some thermal cracking. Therefore, to separate the h~gher molecular weight and higher boiling fractions from crude, specialized processing ateps must be used. Normally, the first step is to sub- ject the bottoms fraction from an atmospheric cruds stil vacuum distillation.
Vacuum distillation also has it limitations in the degree of pressure reduction feasible in large size commercial equipment. After vacuum distillation, there are still some valuable oils left in the vacuum reduced crude. These valuable oils are recovered by solvent processing. The first application of solvent processing in refining was the recovery of heavy lube oil base stocks by propane deasphalting. In order to recover more oll from the crude, higher molecular weight solvents such as butane, and even pentane, have been employed.
Deasphaltlng was developed more than 40 years ago as a joint effort of Kellogg, Standard Oil Co. of New Jersey, Standard Oil Co. of Indiana, and Union Oil Co. of California. The objective of their combined research efforts was the recovery of very heavy lubricating oils, generally known as "bright stocks" or cylinder stock from asphalt base etudes. Since these valuable heavy lubes could not be distilled readily without thermal degradation, they were available only from paraffin base etudes, such as Pennsylvania, which contained little or no asphalt. From these etudes, the heaviest fractions could be economically recovered by steam or clay refining.
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The separation of residual fractionsfrc°masphalt base etudes into oil and asphalt fractions was first performed on a production scale by mixing the residue of vacuum distillation with propane (or mixtures of "normally g;~scous"
hydrocarbon~and continously decanting the resulting phases in a suitable vessel. Temperature was maintained within about lO0°F of the critical temperature of the solvent, at a level which would regulate the yield cud properties of the deasphalted oil in solution ao~ reject the heavier undesirable components as asphalt.
From this original process, pilot plant development Jn Kellogg's lab- orator), progressed th...