GB636524A - Improvements in or relating to the catalytic conversion of hydrocarbons - Google Patents

Abstract

<PICT:0636524/III/1> In the production of hydrocarbons boiling in the gasoline range by contacting vapours of high boiling hydro-carbon oils with particles of solid catalyst in a conversion zone, the suspension of vapours and catalyst is passed upwardly through the conversion zone at a velocity such that phasal separation of the suspension into a lower dense turbulent pseudo liquid phase and an upper relatively dilute phase takes place, and further quantities of catalyst particles are introduced into the dense phase at a rate corresponding to a weight ratio of at least 0.5 parts of catalyst to 1 part high boiling oil and corresponding quantities are withdrawn therefrom, while maintaining the flow of vapours through the zone at a rate determined to maintain the upper level of the dense phase at a suitable height. Feed weight ratio of catalyst to oil is preferably between 2 : 1 and 8 : 1. The crude oil is vaporized in furnace 106 and after separation of liquid residues is <PICT:0636524/III/2> <PICT:0636524/III/3> superheated with or without steam in coil 103. The vapours then formed into a suspension with catalysts from line 31 are injected through line 2 into the lower end of reactor 6 where separation of the suspension into dense and dilute phases takes place. The vapours and catalyst are removed through a restricted coned outlet pipe 7 situated in a separator 9 and strike a baffle 10 which causes separation of catalyst which is collected in the annular portion of the hopper 9, the vapours passing off through line 13 for further treatment. The catalyst is maintained in aerated condition by steam jets 16 and is transferred through pipes 11, 19 to a regenerator 21 with the aid of steam and air admitted through lines 17, 20. In the regenerator 21, which is of similar construction to the reactor 6, separation into dense and dilute phases is effected by controlling the flow of oxygen - containing gas admitted through line 35 and cooler 22. The catalyst after regeneration is separated from the regeneration gases by impingement against baffles and falls into the annular bottom of hopper 24 where it is separated into two streams one stream being recycled through pipe 30 and cooler 22 to the regenerator 21 in order to control the regeneration temperature while the other stream passes down the pipe 31 and is recycled with the fresh feed to the reactor 6. The vapours passing off through line 13 are passed through a cooler 70 to reduce gas concentration and then through a series of cyclone separators 73a, b, c, to remove residual catalyst which is returned to the reactor through hopper 76 and line 14. The vapours then pass through line 82 to a fractionating tower 83 from which (a) naphtha and lighter fraction are recovered at the top; (b) a top condensate is collected through line 97, cooled and recycled as reflux; (c) a light gas oil is removed through line 94 to a stripper 95; (d) a heavy gas oil is removed through line 90; (e) a bottom fraction is removed through line 88 and recycled through line 85 to provide wash oil for washing any residual catalyst out of the vapours; the catalyst-containing oil may be recycled through line 101. A similar series of cyclones 47a, b, c with associated scrubbing and cooling plant is provided to recover catalyst from the regenerating gases leaving the regenerator through line 25. In a modified plant, Fig. 3, the reactor is arranged horizontally and the catalyst is fed to and withdrawn from the conversion and regeneration zones by inlets and outlets separate from these for the vapours or gases. Heavy oil vapours are fed through lines 3a, 5a, to the conversion zone 6a, while regenerated catalyst is supplied through line 1a. The vapours pass off through lines 8a, 13a to recovery plant 112. The catalyst flows laterally across the reactor and is removed through standpipe 11a to the regenerator 21a, the level of the dense phase being adjusted by valves 18a. The regenerator is supplied with oxidizing gases which are removed through lines 23a and cooler 45a to separators and recovery plant 53a. The regenerated catalyst is removed through stand pipes 30a and 31a, the catalyst removed through 30a being recycled to the regenerator through cooler 22a while the p standpipe 31a supplies catalyst feed to the reactor through line 1a. Detailed tables showing the reaction conditions employed in cracking Mid Continent gas oil in presence of superfiltrol as catalyst are given in the Specification. Specification 527,307, U.S.A. Specifications 1,553,539 and 2,253,486 are referred to.