Process and apparatus for contacting feed and catalyst with improved fluid dynamics

1 . A reactor for contacting a feed stream with a catalyst stream comprising:

a reaction chamber comprising a vertical wall and defining an inner diameter and a height;

a catalyst inlet for delivering said catalyst stream to said reaction chamber, a feed inlet for charging feed to said reaction chamber; and a product outlet for removing a product stream from said reaction chamber;

said reaction chamber including an aspect ratio between about 0 . 7 and about 1 . 3 for establishing a dense catalyst bed in the reaction chamber while minimizing hot residence time,

a separation chamber in communication with said reaction chamber; and

a recycle pipe with an inlet end connected to said separation chamber and an outlet end connected to said reaction chamber for recycling spent catalyst to said reaction chamber.

2 . The reactor of claim 1 wherein said vertical wall defines said inner diameter and said height that provides said aspect ratio.

3 . The reactor of claim 1 wherein said vertical wall is a cylinder and said height is of the vertical portion of the wall between ends that have a graduated inner diameter and said inner diameter is the inner diameter of said cylinder.

4 . The reactor of claim 1 wherein said aspect ratio is between about 0 . 8 and about 1.2.

5 . The reactor of claim 4 wherein said aspect ratio is between about 0.85 and about 1.1.

6 . The reactor of claim 1 further comprising a separation chamber in communication with said reaction chamber.

7 . The reactor of claim 1 further comprising a separator in said separation chamber for separating catalyst from product gas.

8 . The reactor of claim 7 further comprising a recycle pipe with an inlet end connected to said separation chamber and an outlet end connected to said reaction chamber for recycling catalyst to said reaction chamber.

9 . A process for contacting a feed stream with fluidized catalyst comprising:

charging said feed stream to a reaction chamber having an aspect ratio of about 0.7 to about 1.3;

contacting said feed stream with a catalyst stream to produce a product gas stream and spent catalyst;

separating said product gas stream from said spent catalyst; and

recycling said spent catalyst back to said reaction chamber.

10 . The process of claim 9 further comprising generating a dense catalyst bed in said reaction chamber of about 1.5 m (5 ft) to about 6 m (20 ft) tall.

11 . The process of claim 10 wherein said dense bed has a density of about 320 kg/m 3 (20 lb/ft 3 ) to about 480 kg/m 3 (30 lb/ft 3 ).

12 . The process of claim 9 wherein a hot residence time of said feed stream is between about 1.5 and 7 seconds.

13 . The process of claim 9 wherein the feed and catalyst ascend in the chamber at a gas velocity of about 1.2 m/s (4 ft/s) to about 2.4 m/s (8 ft/s).

14 . The process of claim 9 wherein said catalyst is recirculated at a ratio of about 0.5 to about 6 on a weight basis relative to regenerated catalyst fed to the reactor.

15 . The process of claim 9 wherein said aspect ratio is between about 0.8 and about 1.2.

16 . The process of claim 15 wherein said aspect ratio is between about 0.85 and about 1.1.

17 . A process for contacting a feed stream with fluidized catalyst comprising:

charging said feed stream to a reaction chamber having an aspect ratio of about 0.7 to about 1.3;

contacting said feed stream with a catalyst stream to produce a product gas stream and spent catalyst;

separating said product gas stream from said spent catalyst;

passing a portion of said spent catalyst back to said reaction chamber and another portion of said spent catalyst to a catalyst regenerator; and

generating a dense catalyst bed in said reaction chamber of 1.5 m (5 ft) to 6 m (20 ft) tall.

18 . The process of claim 17 wherein a hot residence time of said feed stream is between about 1.5 and 7 seconds.