GB885810A - Improvements in or relating to solvent extraction processes - Google Patents

Abstract

Relatively aromatic and relatively paraffinic hydrocarbon mixtures are obtained by solvent extraction of a reformed naphtha with a solvent selective for aromatics, in counter-current to which is passed a kerosene counter solvent containing saturated and aromatic hydrocarbons and withdrawing an extract containing the naphtha aromatics and some kerosene aromatics and a raffinate comprising naphtha saturates and the kerosene of reduced aromatic content. The reformed naphtha is preferably obtained from a straight run naphtha obtained from a crude from which the kerosene is also obtained. The reformate should be bottomed and preferably also topped to obtain a heart cut, should boil in the range 35-220 DEG C. and should contain less than 2% bicyclic aromatics. The kerosene preferably has an I.B.P. 0-30 DEG C. above the end point of the naphtha and may be separated into a light and a heavy fraction, the heavy fraction being used as counter solvent, and the light fraction being withdrawn or being introduced to the extraction with the reformate at a central portion of the extraction zone, or being reformed together with the straight run naphtha. The kerosene will generally boil in the range 150-275 DEG C. and will preferably lose at least 25% of its bicyclic aromatics to the solvent. The solvent may be a glycol or sulfolane and may contain water and preferably at least 25% of any dissolved bicyclic aromatics are removed in the stripping before reusing the solvent. Both the aromatic extract and the raffinate may be separated into light and heavy fractions.ALSO:Relatively aromatic and relatively paraffinic hydrocarbon mixtures are obtained by solvent extraction of a reformed naphtha with a solvent selective for aromatics, in counter-current to which is passed a kerosene solvent containing saturated and aromatic hydrocarbons and withdrawing an extract containing the naphtha aromatics and some kerosene aromatics and a raffinate comprising naphtha saturates and the kerosene of reduced aromatic content. The reformed naphtha is preferably obtained from a straight run naphtha obtained from a crude from which the kerosene is also obtained. The reformate should be bottomed and preferably also topped to obtain a heart cut, should boil in the range 35 DEG C.-220 DEG C. and should contain less than 2% bicyclic aromatics. The kerosene preferably has an I.B.P. 0 DEG C.-30 DEG C. above the end point of the naphtha and may be separated into a light and a heavy fraction, the heavy fraction being used as counter solvent, and the light fraction being withdrawn or being introduced to the extraction with the reformate at a central portion of the extraction zone, or being reformed together with the straight run naphtha. The kerosene will generally boil in the range 150 DEG C.-275 DEG C. and will preferably lose at least 25% of its bicyclic aromatics to the solvent. The solvent may be a glycol or sulfolane and may contain water and preferably at least 25% of any dissolved bicyclic aromatics are removed in the stripping before reusing the solvent. Both the aromatic extract and the raffinate may be separated into light and heavy fractions.