Patent GB-413465-A (GB)
Title: Improvements in and relating to the purification of liquid hydrocarbons with liquid sulphur dioxide or mixtures thereof
IPC: C10G21/10
Filed: 1933-05-02
Abstract: In the Edeleanu process for extracting oils with liquid sulphur dioxide and evaporating the sulphur dioxide from the resulting raffinate and extract, the extractor and evaporating stages are provided with level-regulating devices.  The evaporators are also provided with regulators which control a flow of steam through heaters mounted therein, the highest pressure evaporator being maintained at constant pressure and succeeding evaporators at constant temperature.  A level regulator suitable for the evaporators consists of a chamber 6, Fig. 1, provided with a float 7 mounted on a rod 8 which projects in a lower valve chamber 3 and is provided with cones 9 and 10 which engage throats 11 and 12. Liquid in the evaporator 1 passes through the float chamber through pipes 4 and 5 and flows through a pipe 2 to the lower valve chamber 3.  When the volume of liquid flowing through the exit pipe 14 exceeds a predetermined amount, the level in the float chamber falls and the float descends closing passages 11 and 12, whereby the flow of liquid is throttled.  The restricted outflow enables the level in the evaporator 1 to rise, whereupon the float is restored to its original position.  The regulators mounted on the extractor are similar in construction, but the valves 9, 10 and associated throats 11, 12 are inverted, the controlled stream of liquid flowing through the pipe 2 into the chamber 1.  In an Edeleanu plant, Fig. 2, oil distillate is fed through a pipe 16 to the base of a vertical extraction column 15 through which it rises in counter current with a descending stream of cold sulphur dioxide or a mixture thereof and benzol admitted to the top of the extractor from a tank 18.  The raffinate is drawn off through a pipe 22 and pump 23 and passes to a series of evaporating stages.  A part of the raffinate is taken off through a byepass pipe 24 after the pump 23 and returns to the valve chamber of a regulator 25 which maintains the upper level constant.  The extract is drawn off from the base of the extractor through a pipe 28, which is also provided with a byepass pipe 30 connected to a level regulator 27. The extract then flows through a heat exchanger 35 to a heater 36 connected to a high pressure evaporator 37 in which sulphur dioxide is removed through a pipe 38 and is fed into a heater 42 attached to the next evaporator 44.  The resulting extract flows from the base of the evaporator into the heater 42, the level of extract in the evaporator 37 being maintained constant by a regulator 40 which throttles the extract flowing into the next lower pressure stage 44. The extract flows through the evaporating stages 44, 52, 58, each provided with heaters and level regulators.  The final evaporating stage 58 is effected in a vacuum maintained by a pump 75.  The raffinate is similarly treated in heat exchanger 34 and evaporators 45, 53 and 59, each provided with level-regulating devices, the last evaporator operating in vacuo.  From the final low pressure evaporators the raffinate and extract free from sulphur dioxide pass through the heat exchangers 34, 35 respectively and into storage tanks.  The sulphur dioxide vapours removed in the evaporators of the <PICT:0413465/III/1> <PICT:0413465/III/2> high pressure stages in each series are collected in pipes 83, 84 and return to a condenser 82.  Vapours removed from low pressure stages are drawn off in pipes 72, 73 by the pump 75 which forces the vapours into a compression pump 80 which also draws off vapours through pipes 76, 77, 78 and passes the compressed vapours to the condenser 82.  The vertical extractor may be replaced by horizontal settling tanks combined with mixing devices, the oil and sulphur dioxide flowing through the series of tanks in counter current.  If desired, the first and last evaporating stages only are provided with level regulators.