Product recovery in gas-solids reactors

Abstract

A gas-solids reaction system is provided for improving product recovery in a multiple reactor reaction system. The solids of the product gas-solids flows from the multiple reactors are separated out in a separation vessel having a baffled transition zone. Additional product vapor is stripped from the solids as the solids pass through the baffled transition zone. The solids are then returned to the multiple reactors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a reaction system according to an embodiment of the invention.

FIGS. 2A and 2B schematically show a portion of a reaction system according to an embodiment of the invention.

FIG. 3 shows expected performance characteristics for an apparatus according to an embodiment of the invention.

FIG. 4 schematically shows an apparatus according to an embodiment of the invention.

FIG. 5 schematically shows an apparatus according to an embodiment of the invention.

FIG. 6 shows results of operation of an apparatus according to an embodiment of the invention.

FIG. 7 shows results of operation of an apparatus according to an embodiment of the invention.

FIG. 8 shows results of operation of an apparatus according to an embodiment of the invention.

Claims

1. A method for separating flowing solids comprising: separating from a gas-solids flow a higher density flow comprising a majority of the solids contained in the gas-solids flow;conducting the solids from the higher density flow through a transition zone at a transition zone solids flux of at least about

2. The method of claim 1, wherein the transition zone comprises (a) a solids inlet,(b) a solids outlet having an area A, and(c) a displacing gas inlet, located a vertical distance D from the solids outlet wherein D and A are related by the function D=KA0.5 with K ranging from about 0.3 to about 1.5.

3. The method of claim 2, wherein the transition zone comprises at least one baffle layer, and wherein the displacing gas inlets are either (i) proximate to the baffle layer closest to the solids outlet or (ii) between the solids outlet and the baffle layer closest to the solids outlet.

4. The method of claim 2, wherein the transition zone comprises at least one pair of baffle layers, and wherein an orientation of one layer of the pair of baffle layers is rotated by about 90 degrees relative to the second layer of the pair of baffle layers.

5. The method of claim 1, wherein the displacing gas within the transition zone has a gas superficial velocity of at least about 0.03 m/sec.

6. The method of claim 1, wherein (i) the solids comprise catalyst particles containing molecular sieve with hydrocarbon and/or oxygenated hydrocarbon thereon or therein, (ii) wherein the hydrocarbon and/or oxygenated hydrocarbon is displaced from the catalyst particles in the transition zone at a displacing efficiency of at least about 50%.

7. The method of claim 6, wherein the displacing gas is steam, and the steam has a gas superficial velocity in the transition zone of at least about 0.09 meters per second.

8. The method of claim 7, wherein (i) the catalyst particles have an average flux through the transition zone ranging from about

9. The method of claim 7 wherein the catalyst is conducted away from the transition zone through the solids outlet and into a standpipe.

10. The method of claim 7 where the transition zone comprises a plurality of solids outlets, each of the solids outlets having a cross sectional area A, and wherein a portion of the catalyst is conducted away from the transition zone through each of the plurality solids outlets into a plurality of standpipes, each of the standpipes being of even cross sectional area with the solids outlets and being directly connected to one of the solids outlets.

11. The method of claim 10, wherein at least a portion of the catalyst in the transition zone is in a fluidized bed, the fluidized bed having a density gradient of about 53 kg/m3-m or less, and wherein there is a volume fraction of bubbles at the catalyst outlet of at least about 0.00005.

12. The method of claim 7 wherein the catalyst particles contain SAPO 34 molecular sieve, the catalyst particles being characterized by a size distribution of (i) about 95 wt. % of the catalyst particles have an average size less than about 125 micrometers,(ii) about 90 wt. % of the catalyst particles have an average size less than about 110 micrometers,(iii) about 80 wt. % of the catalyst particles have an average size less than about 96 micrometers,(iv) about 70 wt. % of the catalyst particles have an average size less than about 88 micrometers,(v) about 60 wt. % of the catalyst particles have an average size less than about 83 micrometers,(vi) about 50 wt. % of the catalyst particles have an average size less than about 78 micrometers,(vii) about 40 wt. % of the catalyst particles have an average size less than about 74 micrometers,(viii) about 30 wt. % of the catalyst particles have an average size less than about 69 micrometers,(ix) about 20 wt. % of the catalyst particles have an average size less than about 65 micrometers,(x) about 10 wt. % of the catalyst particles have an average size less than about 59 micrometers,(xi) about 5 wt. % of the catalyst particles have an average size less than about 54 micrometers,(xii) about 1 wt. % of the catalyst particles have an average size less than about 46 micrometers, and(xiii) no more than about 0.5 wt. % of the catalyst particles have an average size less than about 44 micrometers;the wt. percents being based on the total weight of the catalyst particles.

13. The method of claim 9 wherein the transition zone comprises a plurality of solids outlets, each solids outlet having a cross sectional area A, with each of the solids outlets being connected to one of a plurality of standpipes, with each standpipe having a cross sectional area equal to about A.

14. A method for making olefins, comprising contacting a feed containing at least one oxygenate with a SAPO-containing catalyst in a riser reactor,separating the catalyst particles from the olefins and conducting at least a portion of the catalyst to a transition zone having a catalyst flux of at least about

15. The method of claim 14, wherein the transition zone comprises (a) a catalyst inlet,(b) a catalyst outlet having an area A, and(c) a displacing gas inlet, located a vertical distance D from the catalyst outlet wherein D and A are related by the function D=KA0.5 with K ranging from about 0.3 to about 1.5.

16. The method of claim 15 wherein the catalyst is in the form of catalyst particles containing SAPO molecular sieve, the catalyst particles being characterized by a size distribution of (i) about 95 wt. % of the catalyst particles have an average size less than about 125 micrometers,(ii) about 90 wt. % of the catalyst particles have an average size less than about 110 micrometers,(iii) about 80 wt. % of the catalyst particles have an average size less than about 96 micrometers,(iv) about 70 wt. % of the catalyst particles have an average size less than about 88 micrometers,(v) about 60 wt. % of the catalyst particles have an average size less than about 83 micrometers,(vi) about 50 wt. % of the catalyst particles have an average size less than about 78 micrometers,(vii) about 40 wt. % of the catalyst particles have an average size less than about 74 micrometers,(viii) about 30 wt. % of the catalyst particles have an average size less than about 69 micrometers,(ix) about 20 wt. % of the catalyst particles have an average size less than about 65 micrometers,(x) about 10 wt. % of the catalyst particles have an average size less than about 59 micrometers,(xi) about 5 wt. % of the catalyst particles have an average size less than about 54 micrometers,(xii) about 1 wt. % of the catalyst particles have an average size less than about 46 micrometers, and(xiii) no more than about 0.5 wt. % of the catalyst particles have an average size less than about 44 micrometers;the wt. percents being based on the total weight of the catalyst particles.

17. The method of claim 16, wherein (i) the catalyst particles have an average flux through the transition zone ranging from about

18. The method of claim 17 wherein the transition zone comprises a plurality of catalyst outlets, each of the catalyst outlets having a cross sectional area equal to A, and wherein a portion of the catalyst is conducted away from the transition zone through each of the plurality catalyst outlets into a plurality of standpipes and then to the riser reactor, each of the standpipes being of even cross sectional area with the catalyst outlets, and wherein the catalyst flux in the standpipes ranges from about 488 Kg/m2 sec to about 1710 Kg/m2 sec.

19. A method for separating flowing catalyst particles comprising: separating from a gas-catalyst flow a higher density flow comprising a majority of the catalyst particles contained in the gas-catalyst flow;conducting the catalyst particles from the higher density flow through a transition zone at a transition zone catalyst flux ranging from about

20. A method for separating solids from a gas-solids flow comprising: producing a gas-solids flow by performing an oxygenate to olefin conversion reaction in a reactor;separating from the gas-solids flow a higher density flow comprising a majority of the solids contained in the gas-solids flow;conducting the solids from each higher density flow to a transition zone;conducting the solids from the higher density flow through a transition zone at a transition zone solids flux of at least about

21. The method of claim 20, wherein the transition zone comprises a plurality of baffle layers, and wherein the displacing gas inlets are either (i) proximate to the baffle layer closest to the solids outlet or (ii) between the solids outlet and the baffle layer closest to the solids outlet.

22. The method of claim 20, wherein the transition zone comprises at least one pair of baffle layers, and wherein an orientation of one layer of the pair of baffle layers is rotated by about 90 degrees relative to the second layer of the pair of baffle layers.

23. The method of claim 20, wherein a superficial velocity of the displacing gas within the transition zone is about 0.03 m/sec or greater.

24. The method of claim 20, wherein (i) the solids comprise catalyst particles containing molecular sieve with hydrocarbon and/or oxygenated hydrocarbon thereon or therein, (ii) wherein the hydrocarbon and/or oxygenated hydrocarbon is stripped from the catalyst particles in the transition zone at a stripping efficiency of at least about 50%.

25. The method of claim 24, wherein the displacing gas is steam, and the steam has a gas superficial velocity in the transition zone of at least 0.09 meters per second.

26. The method of claim 25, wherein within the transition zone (i) the average catalyst flux ranges from about

27. The method of claim 26 wherein the catalyst is conducted away from the transition zone through the solids outlet and into a standpipe having a standpipe cross-sectional area no greater than A, and then from the standpipe to the olefin conversion reactor.

28. The method of claim 27 the transition zone comprises a plurality of solids outlets, with each solids outlet being connected to at least one of a plurality of standpipes.

29. The method of claim 27 wherein the transition zone comprises a plurality of solids outlets, each of the solids outlets having a cross sectional area equal to A, and wherein a portion of the catalyst is conducted away from the transition zone through each of the plurality solids outlets into a plurality of standpipes to the olefin conversion reactor, each of the standpipes being of even cross sectional area with the solids outlets and having (i) an upstream end directly connected to one of the solids outlets and (ii) a downstream end.

30. The method of claim 29 wherein the olefin conversion reactor comprises a plurality of riser reactors, where the catalyst is conducted from the downstream end of each standpipe into at least one riser of the riser reactor.

31. The method of claim 27, wherein at least a portion of the catalyst in the transition zone is in a fluidized bed, the fluidized bed having a density gradient of about 53 kg/m3-m or less, and wherein there is a volume fraction of bubbles at the catalyst outlet of at least about 0.00005.

32. The method of claim 24 wherein the catalyst comprises SAPO-5, SAPO-8, SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, SAPO-56, the metal containing forms thereof, and mixtures thereof.

33. The method of claim 20, further comprising separating from the gas-solids flow a product comprising olefin and then polymerizing at least a portion of the olefin to make at least one polyolefin.