GB600801A - Improvements relating to the production of high grade aviation or motor fuels by fractional distillation - Google Patents

Abstract

<PICT:0600801/III/1> Closely cut petroleum fractions are obtained by fractionating a petroleum distillate in a column under conditions such that the ratio of the overhead or bottom products to the feed is controlled in accordance with the hydrocarbon content of the feed stock as established by analysis. In an example, the feed stock was analysed by determining its true boiling point curve using a laboratory batch column equivalent to at least 20 theoretical plates. The feedstock was found to have 12 per cent boiling below 72 DEG C. and distillation conditions were arranged so that with top and bottom column temperatures of 180 DEG F. and 280 DEG F. respectively, a reflux temperature of 125 DEG F., and an operating vapour velocity of 150,000 lbs. per hour, a reboil ratio (in lbs. per hour of vapours from reboiler and bottoms respectively) of 3.8-1 was maintained. A column e is provided with a reboiler m and an off-take pump o, operation of which is controlled by a level controller n to maintain a constant level in the bottom of the column. Overhead is withdrawn through condenser f and the overhead product is collected in tank g part being recirculated as reflux by the pump k, while the remainder is withdrawn by pump l; operation of pump k is controlled by controller h in tank g. The feedstock is supplied through two or more tanks, so that when the feedstock in one of the tanks is being analysed supply can be continued from one of the other tanks. Specification 600,551 is referred to.