GB708956A - Hydrocarbon conversion process - Google Patents

Abstract

A heavy hydrocarbon oil such as crude petroleum or topped crude petroleum, is heated so that partial vaporization is effected, the mixture of residual oil and vapours is passed to a phase separator, the vapours from the separator are fed to a cracking zone containing a moving or fluidized bed of solid particles (catalytic or inert), the residual oil from the separator is submitted to vacuum distillation until a heavy material having an ASTM soft point between 60 DEG and 90 DEG F. remains as residue, the vacuum distillate is condensed, and the condensate is introduced as liquid feed <PICT:0708956/III/1> into the cracking zone. The heavy material withdrawn from the vacuum distillation zone may be mixed with a fraction of the cracked products boiling above 400 DEG F. to give a fuel oil having a viscosity (Saybolt Furol) between 45 and 300 seconds. The contact material may be a synthetic association of silica and/or alumina to which small amounts of other materials, such as metal oxides, can be added. Other contact materials mentioned are natural or treated clays, bauxite, mullite, zirkite, corhart, metals, and stones. Instead of passing the vapours from the separator and the condensate from the vacuum distillation to a cracking zone they may be passed to a zone in which reforming, hydrogenation, dehydrogenation, aromatization, or alkylation is effected. The feed stock is charged through pipe 1 to furnace 2, wherein it is heated to a temperature between 700 DEG and 900 DEG F.; and the mixture of liquid and vapour so produced is passed to separator 4 which is maintained at a pressure between 10 and 30 p.s.i.g. If desired, steam may be introduced into the separator through pipe 5. Vapours at a temperature between 600 DEG and 850 DEG F. leave the separator through pipe 7, and are fed to the lower part of reactor 74, which contains a fluidized bed of hot, finely-divided contact material. If necessary, the vaporous feed can be heated further before being fed to reactor 74, by by-passing some or all of it through furnace 9. The liquid from separator 4 passes through pipe 15 into vacuum tower 16 (which can have two, three or more plates) maintained at an absolute pressure of 1 to 6 lbs./square inch by means of pump 20. Vapours leave the head of tower 16 at a temperature between 550 DEG and 775 DEG F., and are condensed in condenser 18. The condensate is collected in tank 19. Part of the condensate may, if desired, be pumped to the top of tower 16 as reflux; and an upper side stream from tower 16 may be pumped, via a condenser, to separator 4. Liquid from tank 19 is pumped as liquid feed to reactor 74 via pipe 22. Residual material at a temperature between 600 DEG and 800 DEG F. is withdrawn from the base of tower 16 through pipe 23, and is utilized to heat the liquid flowing to reactor 74 through pipe 22, by means of heat-exchanger 28. In an alternative procedure, the liquid feed may be preheated by heat-exchange with the vapours leaving the head of tower 16. If desired, additional heating (up to 800 DEG F.) of the liquid feed is effected by by-passing some or all of it through furnace 29. The liquid feed is sprayed into the upper part of reactor 74 through a nozzle 79. The conversion products are withdrawn from the reactor through pipe 80. Contaminated contact materials passes down standpipe 75, and is lifted in a fluidized state through conduit 76 to regenerator 70 by oxidizing gas introduced via valve 77. The regenerated catalyst withdrawn from the regenerator is brought to the desired contact temperature by means of heat-exchanger 73 in standpipe 71, and is then returned to reactor 74 through conduit 72 by means of carrying gas such as steam, flue gas or gaseous hydrocarbons, supplied via valve 73. In another embodiment, the regenerated catalyst is conveyed to the reactor by means of the vapours from separator 4; and the liquid feed from tank 19 is introduced into the stream before it reaches the reactor. The products withdrawn from the top of the reactor may be passed into a flash tower, the distillate from which is passed on to further recovery operations, while the liquid bottoms are recycled to the reactor. In the product recovery system, material boiling above gasoline may be recovered as recycle oil by fractionation. Part of the recycle oil may be employed for cutting back the bottom product from tower 16 to a fuel oil of suitable viscosity. The remainder may be recycled to furnace 2. Specification 593,778 is referred to.