Method and apparatus for regenerating an iron-based Fischer-Tropsch catalyst
View Patent ↗Solvent extraction is used to remove wax and contaminants from an iron-based Fischer-Tropsch catalyst in a natural circulation continuous-flow system. The wax-free catalyst is then subjected to controlled oxidation to convert the iron to its initial oxidized state, Fe 2 O 3 . Reactivation of the oxide catalyst precursor is carried out by addition of synthesis gas.
1. An apparatus comprising:
a slurry bubble column extractor comprising an extraction solvent inlet configured for introduction of an extraction solvent into the slurry bubble column extractor, a gas inlet configured for introduction of gas into the slurry bubble column extractor, an overhead gas outlet configured for removal of overhead gas from the slurry bubble column extractor, a slurry inlet configured for recycle of catalyst to the slurry bubble column extractor, and a slurry outlet configured for removal of slurry from the slurry bubble column extractor;
a dynamic settler comprising an inlet fluidly connected with said slurry outlet of said slurry bubble column extractor via a first conduit, and an outlet fluidly connected with said slurry inlet of said slurry bubble column extractor via a second conduit, wherein said dynamic settler is operable to separate a substantially catalyst-free liquid stream from a catalyst stream;
a flash vessel fluidly connected with said dynamic settler via a clarified liquid conduit configured for removal of said substantially catalyst-free liquid stream from said dynamic settler, wherein said flash vessel is configured for separation of a vapor comprising vaporized extraction solvent from a liquid comprising Fischer-Tropsch wax;
a gas/liquid separator positioned downstream of said flash vessel and fluidly connected therewith such that at least a portion of the extraction solvent removed as vapor from the flash vessel can be introduced into the gas/liquid separator, wherein said gas/liquid separator is configured for separation of an uncondensed gas from condensed extraction solvent; and
a recycle line configured such that at least a portion of said condensed extraction solvent can be introduced into said extraction solvent inlet of said slurry bubble column extractor.
2. The apparatus of claim 1 wherein said first conduit and said second conduit are downward sloping, such that said apparatus is configured for natural circulation of a catalyst slurry from said slurry bubble column extractor into said dynamic settler via said first downward sloping conduit and for return of said catalyst stream to said slurry bubble column extractor via said second downward sloping conduit.
3. The apparatus of claim 1 further comprising valves on said first and second conduits whereby said dynamic settler can be isolated from said slurry bubble column extractor.
4. The apparatus of claim 1 wherein said dynamic settler comprises a degassed slurry conduit extending approximately 80% of the height of said dynamic settler from the top thereof.
5. The apparatus of claim 1 wherein said clarified liquid conduit is configured for removal of said substantially catalyst-free liquid stream from a top portion of said dynamic settler.
6. The apparatus of claim 1 further comprising a pressure reduction valve upstream of said flash vessel and downstream of said dynamic settler, said pressure reduction valve configured to reduce the pressure of said substantially catalyst-free liquid stream to a pressure at which a majority of said solvent vaporizes.
7. The apparatus of claim 1 further comprising a solvent selected from the group consisting of hexane, hexene, heptane, heptene, tetrahydrofuran, Fischer-Tropsch naphtha, and combinations thereof.
8. The apparatus of claim 1 further comprising a wax collection tank downstream of and fluidly connected with said flash vessel and configured for storage of Fischer-Tropsch wax separated from said solvent during wax removal.
9. The apparatus of claim 1 further comprising:
a cooler configured to cool overhead gases from said slurry bubble column extractor, thus condensing a first liquid product; and
a first separator configured to separate uncondensed gas from said first liquid product.
10. The apparatus of claim 9 further comprising a flare configured for flaring a portion of said uncondensed gas separated from said first liquid product in said first separator, a portion of said gas separated from said condensed extraction solvent in said gas/liquid separator, or both.
11. The apparatus of claim 9 further comprising a recycle line fluidly connecting said first separator with said slurry bubble column extractor, whereby a portion of said uncondensed gas separated from said first liquid product in said first separator can be recycled to said slurry bubble column extractor.
12. The apparatus of claim 9 wherein said first separator is fluidly connected with said slurry bubble column extractor via a gas outlet conduit.
13. The apparatus of claim 12 wherein said dynamic settler further comprises a gas outlet fluidly connected with said gas outlet conduit upstream of said first separator.
14. The apparatus of claim 9 further comprising a liquid storage vessel positioned downstream of said gas/liquid separator, said first separator, or both, such that said condensed extraction solvent, said first liquid product, or both can be stored therein.
15. The apparatus of claim 14 further comprising a recycle line fluidly connecting said liquid storage vessel with said slurry bubble column extractor such that a portion of said first liquid product, a portion of said condensed extraction solvent, or a portion of both can be recycled to said slurry bubble column extractor.
16. The apparatus of claim 1 further comprising a gas distributor configured to distribute a gas uniformly across a cross section of said slurry bubble column extractor.
17. The apparatus of claim 16 wherein said gas distributor comprises a sintered metal plate.