Draft tube for catalyst rejuvenation and distribution

Abstract

Catalyst in a slurry phase reactor is rejuvenated and uniformly distributed in said reactor using a substantially vertical draft tube fully immersed in the slurry which utilizes a rejuvenating gas injected substantially near the bottom of the substantially vertical draft tube whereby catalyst near the bottom of the slurry phase reactor is drawn up the draft tube and discharged from the top of the draft tube near the top of the slurry phase in said reactor.

What is claimed is:  
     
       1. A method for rejuvenating reversibly deactivated particulate hydrocarbon synthesis catalyst in a slurry phase reactor, said method comprising the use of substantially vertical draft tube means, open at both ends, fully immersed in the slurry containing the catalyst and injecting a hydrogen containing gas at or substantially near the bottom of said draft tube means thereby lifting catalyst in slurry from the bottom of the slurry phase reactor into and through the open bottom end of the draft tube means, rejuvenating catalyst in the presence of said hydrogen containing gas in the vertical draft tube means and ejecting the rejuvenated catalyst into the top of the slurry phase in the slurry phase reactor through the open top of the draft tube means. 
     
     
       2. The method of  claim 1  wherein the cross sectional surface area of the draft tube means occupies from 0.2 to 10% of the cross sectional surface area of the slurry phase reactor. 
     
     
       3. The method of  claim 1  wherein the substantially vertical draft tube means comprises one or more individual draft tubes. 
     
     
       4. The method of  claim 3  wherein when multiple draft tube means are employed no single draft tube constitutes more than 50% of the total cross sectional area of the total draft tube means. 
     
     
       5. The method of  claim 3  wherein the individual draft tube means of the draft tube means possess a diameter such that a sufficiently lower slurry density is maintained in the draft tubes than in the surrounding slurry in the reactor vessel. 
     
     
       6. The method of  claim 1  wherein the open bottom end of the draft tube means is located at a height of from 0.1 to 1 foot above the bottom of the slurry phase reactor. 
     
     
       7. The method of  claim 1  wherein the hydrogen containing gas is injected into the substantially vertical draft tube means at a rate such that the superficial gas velocity in the draft tube means is at least 0.2 to 40 times the superficial gas velocity of the gases in the slurry phase reactor thereby permitting sufficient residence time in the draft tube means for catalyst regeneration - rejuvenation to occur. 
     
     
       8. The method of  claim 1  wherein the bottom end of the substantially vertical draft tube means is fitted with gas deflecting means to minimize entry of reactant gases into the draft tube means. 
     
     
       9. A method for producing hydrocarbons in a slurry phase reactor utilizing a hydrocarbon synthesis catalyst which comprises rejuvenating said hydrocarbon synthesis catalyst in accordance with the method of  claim 1 . 
     
     
       10. The method of  claim 9  wherein said slurry comprises the product of said hydrocarbon synthesis including C 5+    hydrocarbons.   
     
     
       11. The method of  claim 10  wherein said slurry comprises C 5   -C   100    hydrocarbons.   
     
     
       12. The method of  claim 11  wherein said slurry comprises Fischer- Tropsch waxes.   
     
     
       13. The method of  claim 9  wherein said hydrocarbon synthesis catalyst comprises a Fischer- Tropsch catalyst.   
     
     
       14. The method of  claim 13  wherein said Fischer- Tropsch catalyst comprises a Group VIII metal selected from the group consisting of iron and cobalt.