GB407193A - Improvements in and relating to the cracking of hydrocarbon oils - Google Patents

Abstract

Motor fuel is obtained by cracking in the vapour phase an oil which is completely vaporizable, the oil being rapidly heated to vaporize it at temperatures between 850 and 975 DEG F., and the vapours being maintained at this temperature under a pressure of 100-400 lbs. per square inch for a period of time so that the minimum total yield per pass is between 2.5 and 13 per cent, and not more than 15 per cent of the oil is converted during the rapid heating and at least 85 per cent after such rapid heating. Oil preheated in a coil 23 is passed through a pipe 26 into a fractionating tower 16. A selected condensate is collected in a plate 20 and fed by a pump 29 through vaporising and rapid heatings coils 10, 10<a> in a furnace 5 and thence through the main cracking coil 11. The cracked products are cooled rapidly by injection through a pipe 14 into a bath of heavy residues maintained at the bottom of the tower 16 and kept cool by circulation through a heater 32<c>. Vapours passing off from the top of the tower 16 are condensed in a coil 31 to give the desired product. In a modification, Fig. 2, the cracked vapours are passed through a pipe <PICT:0407193/III/1> <PICT:0407193/III/2> 46 into a large unobstructed reaction chamber 47 where they are maintained under cracking conditions in a quiescent state. The charging stock preheated in coils in a fractionating tower 60 and in a coil in the chamber 47 surrounding the residue outlet 54 is introduced into this chamber through a pipe 52. The vapours pass off through a pipe 51 and mixed with the residues from the chamber 47 are introduced into the tower 60. The final products pass off through a pipe 75 and are condensed in a cooler 76 while a fraction drawn off from a lower plate through a pipe 72 is stripped in a chamber 73 by steam to give a composite pool which is supplied as stock to the cracking coils through pipes 81, 83, the stripped vapours being returned to the tower 60 through a pipe 80.