A fluid catalytic cracking process includes feeding hydrocarbon into a riser in the presence of a catalyst, cracking the hydrocarbon in the riser in the presence of the catalyst to form a cracked stream, and separating the catalyst from the cracked stream. When in a gasoline mode, the hydrocarbon is fed through a first distributor into the riser, and when in a light olefin mode, the hydrocarbon is fed through a second distributor into the riser. The second distributor is positioned at a higher elevation than the first distributor.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational diagram showing an FCC unit.
FIG. 2 is a cross section taken along segment A-A in FIG. 1.
FIG. 3 is a cross section taken along segment B-B in FIG. 1.
FIG. 4 is an elevational diagram showing a feed distributor nozzle.
Claims
1. A fluid catalytic cracking process, comprising:
feeding hydrocarbon into a riser in the presence of a catalyst;cracking said hydrocarbon in said riser in the presence of said catalyst to form a cracked stream, andseparating said catalyst from said cracked stream,
2. The process of claim 1, wherein each one of said distributors comprises a plurality of nozzles having substantially the same elevation and being spaced radially around said riser.
3. The process of claim 1, wherein said separation of catalyst from said cracked stream is performed in a swirl arm arrangement.
4. The process of claim 1, wherein the light olefin mode has residence time of between about 0.5 second and about 2 seconds in said riser.
5. The process of claim 1, wherein propylene-preferential mode has residence time of about 1 to about 2 seconds in said riser.
6. The process of claim 1, wherein gasoline-making mode has residence time of between about 2 seconds and about 5 seconds.
7. The process of claim 1, wherein said FCC process is changeable from one mode to another without shutting the process down.
8. The process of claim 1, wherein said hydrocarbon and steam are fed through same distributor nozzle.
9. The process of claim 1, wherein when in said gasoline mode, said process produces a cracked stream having gasoline vol-% between about 50 and about 70.
10. The process of claim 1, wherein, when in said light olefin mode, said process produces a cracked stream having vol-% of propylene between about 20 and about 40.
11. The process of claim 1, wherein said temperature at the outlet of said riser is between about 490° and about 630° C.
12. The process of claim 1, wherein said catalyst is about 2 to about 20 wt-% medium or smaller pore zeolite while operating in said light olefin mode and less than 0.5 wt-% medium or smaller pore zeolite while operating in said gasoline mode.
13. The process of claim 1, wherein said temperature in said reactor in said light olefin mode is between about 550° and about 590° C.
14. The process of claim 1, wherein said temperature in said reactor in said gasoline-preferential mode is between about 500° and about 550° C.
15. The process of claim 1, wherein more steam is added to the riser when operating in the light olefin mode than when operating in the gasoline mode.
16. The process of claim 1, wherein a greater catalyst to feed ratio is used when operating in the light olefin mode than when operating in the gasoline mode.
17. The process of claim 1 further comprising the step of quenching said cracked stream with a liquid after exiting said riser.
18. A fluid catalytic cracking process, comprising:
feeding hydrocarbon into a first region having a first predetermined elevation in a riser in the presence of a catalyst, wherein said thirst region and said first predetermined elevation are selected to provide a greater yield of light olefins in a light olefin mode;cracking said hydrocarbon in said riser in the presence of said catalyst to form a cracked stream;separating said catalyst from said cracked stream; andchanging from said light olefin mode to a gasoline mode by changing the location of the feed of said hydrocarbon to a second region having a second predetermined elevation lower than that of said first predetermined elevation to produce a smaller yield of light olefins than when operated in the light olefin mode.
19. A fluid catalytic cracking process, comprising:
feeding hydrocarbon into a riser in the presence of a catalyst;cracking said hydrocarbon in said riser in the presence of said catalyst to form a cracked stream; andseparating said catalyst from said cracked stream,
20. The process of claim 19 further comprising the step of introducing C8-feed into said mixing chamber below said riser.
Patent Application
20070205139
