Patent GB-685181-A (GB)
Title: Improvements in the cracking of hydrocarbons
IPC: C10G11/18
Filed: 1951-02-20
Abstract: <PICT:0685181/IV (b)/1> Hydrocarbons are cracked by contacting them with a heated, fluidized-bed of granular-solid material, and the vapours leaving the cracking chamber are filtered by passing them downwards through a fixed-bed of granular-solid material, whereby dust and other impurities are removed from the vapours.  When the cracking in the fluidized-bed does not proceed as completely as desired, the vapours leaving the fluidized-bed may be subjected to after-cracking in the filter-bed.  Chambers I and II both contain coke particles having a grain size of 0-6 mm., which are raised to 850 DEG  C. and brought into a whirling state by the introduction of hot air.  The bed in chamber II is then allowed to become stationary, but the bed in chamber I is kept in a whirling state by the introduction of steam from below.  Petroleum residue is now introduced into chamber I from vessel A, 20 litres of residue being added within 6 minutes, whereupon the temperature of the bed is reduced to 750 DEG  C.  The cracked vapours pass through connection V, and flow down through the stationary bed of hot coke in chamber II, wherein filtration and further cracking take place.  The product leaving the stationary bed contains 25 per cent propylene and butylene, 23 per cent ethylene, 22 per cent methane, and 16 per cent hydrogen.  After the 6-minute cracking period, both beds are reheated to 850 DEG  C. and simultaneously regenerated, by blowing in air. The cracking process is then recommenced, using the bed in chamber II for cracking.  In other processes, polymerization or hydrogenation may be effected in the filter bed.ALSO:<PICT:0685181/III/1> Hydrocarbons are cracked by contacting them with a heated, fluidized-bed of granular-solid material, in particular coke or a catalytic material such as silica gel; and the vapours leaving the cracking chamber are filtered by passing them downwards through a fixed-bed of granular-solid material, whereby dust and other impurities are removed from the vapours.  The same granular material may be used in both beds.  When the filter bed becomes so laden with dust and other impurities that it offers considerable resistance to the passage of the cracked vapours, it is regenerated by blowing in, from below or from the side, air or other regenerating gas, so that the filter bed is set in whirling motion and the impurities are blown or burnt away.  In a continuous process, two filter chambers may be provided so that one is acting as a filter while the other is being regenerated. But a second filter chamber can be dispensed with when the filter bed can also be used for cracking, for in such a case the cracking chamber and the filter chamber are alternatively made to exchange their functions.  Moreover when the cracking in the fluidized-bed may be subjected to after-cracking in the filter bed. Polymerization or hydrogenation may also be effected in the filter bed.  Chambers I and II both contain coke particles having a grain size of 0-6 mm., which are raised to 850 DEG C and brought into a whirling condition by the introduction of hot air.  The bed in chamber II is then allowed to become stationary, but the bed in chamber I is kept in a whirling state by the introduction of steam from below.  Petroleum residue (initial boiling point 360 DEG C) is now introduced into chamber I from vessel A, 20 litres of residue being added within 6 minutes, whereupon the temperature of the bed is reduced to 750 DEG C.  The cracked vapours pass through connection V, and flow down through the stationary bed of coke in chamber II, wherein filtration and further cracking take place.  The product leaving the stationary bed contains 25 per cent propylene and butylene, 23 per cent ethylene, 22 per cent methane, and 16 per cent hydrogen.  After the 6-minute cracking period, both beds are reheated to 850 DEG C and simultaneously regenerated, by blowing in air.  The cracking process is then recommenced, using the bed in chamber II for cracking.  In alternative procedures, the heat necessary for cracking may be produced within the cracking chamber itself by the reaction of oxygen-containing gases with fuels, or the heat may be supplied indirectly through pipes arranged in the chamber.