Patent GB-509268-A (GB)
Title: Recovery of gasoline
IPC: C10G5/00
Filed: 1938-01-18
Abstract: 509,268. Motor fuel. HOUDRY PROCESS CORPORATION. Jan. 18, 1938, No. 1656. Convention date, Feb. 27, 1937. Drawings to Specification. [Class 91] [Also in Group IV] A mixture of hydrocarbons containing hydrocarbons boiling within and below the gasoline range, including normally gaseous olefines, is separated into low vapour pressure gasoline, and a fraction consisting of C4 hydrocarbons with permissibly some of the C3 hydrocarbons, which fraction is polymerized, the liquid polymers obtained being used to increase the yield of gasoline, part of the gaseous products being utilized to adjust its vapour pressure, and the remainder being recycled to the polymerizer. The mixture is fractionated to remove heavy hydrocarbons, those of gasoline boiling range and lighter being condensed, and incondensible gases such as hydrogen and methane, after washing with an absorbent liquid, being discharged. The condensate is stabilized to give low vapour pressure gasoline, and C2 to C4 hydrocarbons, which latter are treated to remove C2 and at least part of the C3 hydrocarbons. The C4 fraction is polymerized, advantageously in liquid phase with a silica, alumina catalyst as described in Specifications 503,913 and 505,369, [both in Group IV]. If the polymers are free from hydrocarbons heavier than gasoline, and the unconverted gases are free from incondensible gases, all the polymers and part of the gases may be added to the low-pressure gasoline. The product may, however, be first separated into liquids and gases, the former being passed to the stabilizing zone or the initial fractionating zone, and the latter in part recirculated to the polymerizer and in part added to the gasoline. If poor in olefines, part of the gases may be dehydrogenated, for example as described in Specification 505,369, and the products returned to the initial condensing or washing stages. Saturated hydrocarbons may be admitted prior to the dehydrogenating zone. In an example, fractions consisting of gasoline and uncondensed gases obtained by cracking are treated. The C4 hydrocarbons comprising about 50 per cent olefines are separated and polymerized at about 300‹ F. and 500 lb./in.<2>, with an activated hydrosilicate of aluminium. The products are separated into a gasoline, which is fed to the stabilizing zone so that the latter discharges a low vapour pressure gasoline comprising both cracking and polymerized products, and a gas fraction part of which is added to the low vapour pressure gasoline to raise the vapour pressure to the desired value, and part returned to the polymerizer. In another operation, the C4 cut fed to the polymerizer is mixed with twice its volume of the gases separated from the polymerization products. The final product from the polymerizer is separated into a gasoline containing some C4 gases, which is added to the cracking gasoline from the stabilizing zone, and a gas fraction which is recycled to the polymerizer. Alternatively, this gas fraction is dehydrogenated with aluminium chromite at about 925‹ F. and fed to the initial washing zone. Specification 482,978 also is referred to. The Specification as open to inspection under Sect. 91 is not limited to the recycling of part of the gases from the polymerizer. The total gases may be added to the gasoline to raise its vapour pressure or a part only added and the remainder removed from the plant. This subject-matter does not appear in the Specification as accepted.