GB792255A - Pyrolytic cracking of heavy oils - Google Patents

Abstract

<PICT:0792255/III/1> In a process for converting heavy oils into a fuel gas, light petroleum products and some heavier products such as gasoline the heavy oils are contacted with a stream of heated inert refractory pebbles which move successively downwards through a heating zone 8 wherein the pebbles are reheated by burning off coke deposited on the pebbles, a pebble distributing zone 24 from which a small portion of the pebbles is fed to the reaction zone 28 through a ring of tubes 36 while the major portion of the pebbles descends by a central conduit 37 and on to which the heavy oils are sprayed by a pipe 41 passing through the duct 37, reaction products are withdrawn from the zone 28 through off-take 45 while the pebbles are removed as two annular streams through conduits 46 extending through a mass 47 of refractory material, e.g. sand, and a transverse support member 48 and pass through a valve 52 and conduit 59 to the chamber 67 of a pneumatic lift having two or more lift pipes 68 to be returned to the heating zone 8 via a disengaging vessel 71. Burners 72 may be supplied with oil or gas through lines 74 and air through lines 73 to supplement the heating by combustion of deposited coke in the heating zone 8. Lines 73 may also supply air for the combustion of deposited coke if air is not supplied as the lift gas in the pneumatic lift. Flue gases leave the zone 8 through a boiler section 20 and a stack 21. Steam is supplied to the reaction zone through line 42 and the temperature in the reaction zone may be between 1100-1500 DEG F. In an example, pebbles enter the heating zone 8 at between 1000-1200 DEG F. and are heated therein to between 1480-1580 DEG F., the temperature in the upper part of the reaction zone being 1180-1300 DEG F. while in the lower part of the reaction zone the temperature level is between 1080-1200 DEG F.