GB759515A - Method for washing liquid hydrocarbons from used solid adsorbents - Google Patents

Abstract

Spent solid adsorbent (of particle size about 4-100 mesh), which has been used in the refining at elevated temperature of liquid hydrocarbons and still has liquid hydrocarbon entrained with it, is freed of the liquid hydrocarbon by passing it while still hot downwardly against a rising flow of a solvent for the hydrocarbon, the adsorbent passing through the solvent mainly in the form of a column but with a body of liquid above the column. In this way, the hot adsorbent entering the liquid body is rapidly cooled to a temperature at which the solvent removes from the adsorbent the entrained hydrocarbon but does not remove to any great extent the impurities which the adsorbent removed from the hydrocarbon in the refining stage. Adsorbents mentioned are fuller's earth, bauxite, bentonite, bonechar, charcoal, magnesium, silicate, heat and acid-activated kaolin, acti-vated carbon, silica gel, alumina gel and mixed silica-alumina gel. Liquid hydrocarbons which may be refined with the aid of the adsorbents include mineral oils and particularly petroleum lubricating oils, distillate fuel oils and lower boiling petroleum fractions. The refining treatment may effect decolorization, neutralization, improvement of demulsibility, the removal of undesired hydrocarbons from liquid mixtures of hydrocarbons by adsorption, or the removal of suspended colloidal or dissolved impurities such as carbon, coke, oxygenand nitrogen-containing compounds and other gum-forming compounds. Petroleum lubricating oils may be diluted with naphtha before refining, in order that the refining may be carried out at a lower temperature. Solvents mentioned are carbon tetrachloride, n-heptane, n-octane, petroleum naphtha and carbon disulphide. Apparatus is described in which hot hydrocarbon oil, for example, petroleum bright stock, is treated countercurrently with adsorbent, for example, in order to decolorize the oil, the spent adsorbent falling by gravity from the bottom of the treater and passing while still hot to the washer. In the washer, the adsorbent forms a descending column, while solvent passes countercurrently thereto and forms a body of liquid above the column. The liquid drawn off from the washer is fractionated to obtain solvent and reclaimed oil, the solvent being recycled to the washer and the reclaimed oil being recycled to the treater. However, some of the liquid drawn off from the washer may be recycled as such, being reintroduced either at a higher point in the washer or into the feedline supplying hot spent adsorbent to the washer, thus aiding in the rapid cooling of the adsorbent. Various constructions of the washer are described. The adsorbent from the washer is dried by means of stripping gas and then passed to a regenerator, wherein carbonaceous contaminants are burnt off. The regenerated adsorbent is then recycled to the treater. In the examples, mineral lubricating oil is decolorized with fuller's earth and the spent fuller's earth is washed with naphtha.