GB770392A - Method and apparatus for continuous percolation of liquid hydrocarbons - Google Patents

Abstract

A method of countercurrently contacting a liquid hydrocarbon with a downwardly moving column of solid absorbent (in the form of particles within the range of 4-100 mesh) comprises maintaining a column of the absorbent along an intermediate portion of a confined elongated treating zone, maintaining a body of contacted liquid in an upper portion of the treating zone immediately above and open to the surface of the column, replenishing the column at its upper end with fresh absorbent in one confined feed stream or a plurality of such streams horizontally spaced, the stream or streams discharging a substantial distance below the surface of the body of contacted liquid in the upper portion of the treating zone, introducing liquid hydrocarbon feed into the lower section of the column of adsorbent so as to force the liquid to flow upwardly into and through the column of adsorbent at a velocity controlled at the liquid inlet which velocity is below that at which the flowing liquid would entrain the adsorbent particles, and withdrawing contacted liquid from the upper portion of the above-mentioned body of contacted liquid hydrocarbon. The method is applicable to the treatment of liquid hydrocarbons, particularly lubricating oils and lower-boiling petroleum fractions which are of low asphalt content, with solid adsorbents for the purpose of removing small amounts of impurities or undesirable contaminants therefrom. Oilpurifying processes to which the method is applicable are decolorization, neutralization, removal of suspended colloidal or dissolved impurities such as carbon, coke, oxygen- or nitrogen-containing and other gum-forming compounds, and improvement of demulsibility properties of the oil. The method is also applicable to the separation of hydrocarbon mixtures by adsorption and to the treatment of absorbents with liquid hydrocarbons such as petroleum naphtha or n-heptane to recover occluded liquid materials such as oil. Adsorbents mentioned are Fuller's <PICT:0770392/III/1> <PICT:0770392/III/2> <PICT:0770392/III/3> earth, bauxite, bone char, bentonite, charcoal, magnesium silicate, heat- and acid-activated kaolin, activated carbon silica gel, alumina gel and silica-alumina gel. After being used for treating hydrocarbon oil, the adsorbent may be washed, dried and burnt, and the regenerated adsorbent thus obtained may be recycled to the oil treatment stage. In Fig. 1, adsorbent from conduit 12 enters vessel 10 through a plurality of pipes 18 and drops through tubes 20, which are suspended from the ends of pipes 18, into the body of contacted liquid hydrocarbon. The adsorbent column 55 is supported on partition 30, spent adsorbent being withdrawn through conduits 37. The liquid hydrocarbon is introduced through pipe 36 and passes through holes 50 in conduit 35 and then through nozzles 33 into the adsorbent column. Treated liquid hydrocarbon is withdrawn through pipe 23. An alternative form of treating apparatus is shown in Fig. 6, while an alternative method of introducing the adsorbent into the apparatus is illustrated in Fig. 7. In a specific example, the method is applied to the decolorization of a petroleum bright stock using fuller's earth as the adsorbent. The bright stock is blended with naphtha before treatment and the spent fuller's earth is freed of oil, this oil being recycled to the decolorization zone. The spent Fuller's earth is then washed, dried, regenerated and finally recycled to the decolorization zone. Specifications 576,058, 770,391, 770,393 and 770,395 are referred to.