Integrated process for conversion of whole crude to light olefins
Light olefins may be produced from a hydrocarbon feed by a method that includes separating the hydrocarbon feed into at least a light gas fraction stream comprising C 1 -C 4 alkanes, a light fraction stream comprising C 5+ alkanes, and a heavy fraction stream. The temperature cut between the light fraction stream and the heavy fraction stream may be at 280° C. to 320° C. The method may further include steam cracking at least a portion of the light gas fraction stream to produce a steam cracked effluent stream and catalytically cracking at least a portion of the light fraction stream and the heavy fraction stream in a steam enhanced catalytic cracker (SECC) to produce a catalytically cracked effluent stream. The steam cracked effluent stream and the catalytically cracked effluent stream may be sent to a product separator to produce the light olefins.
1. A method for producing light olefins from a hydrocarbon feed, the method comprising:
introducing the hydrocarbon feed having an American Petroleum Institute (API) gravity value above 35° into a feed separator to separate the hydrocarbon feed into at least a light gas fraction stream comprising C 1 -C 4 alkanes, a light fraction stream comprising C 5+ alkanes, and a heavy fraction stream, wherein the temperature cut between the light fraction stream and the heavy fraction stream is from 280° C. to 320° C.;
passing the light gas fraction stream to a steam cracker to steam crack at least a portion of the light gas fraction stream and produce a steam cracked effluent stream;
preheating the heavy fraction stream to a temperature of less than or equal to 250° C. by mixing the heavy fraction with steam prior to introduction to a steam enhanced catalytic cracker;
introducing the light fraction stream and the heavy fraction stream to the steam enhanced catalytic cracker (SECC) in the presence of steam and one or more catalysts selected from ZSM-5 and USY to catalytically crack at least a portion of the light fraction stream and the heavy fraction stream and produce a catalytically cracked effluent stream, wherein the weight ratio of steam to the light fraction stream and the heavy fraction stream is from 1:5 to 1:1; and
passing the steam cracked effluent stream and the catalytically cracked effluent stream to a product separator to produce the light olefins;
wherein the light fraction stream has a final boiling point of less than 300° C.
2. The method of claim 1 wherein the product separator also yields a heavy component stream, said heavy component stream comprising cracked naphtha, light cycle oil with components having boiling points from 221° C. to 343° C., and heavy cycle oil with components having boiling points greater than 343° C.;
passing the heavy component stream to a hydrotreater to produce a hydrotreated heavy component stream; and
recycling at least a portion of the hydrotreated heavy component stream to the SECC to catalytically crack at least a portion of the hydrotreated heavy component stream, wherein the weight ratio of steam to hydrocarbon is from 1:5 to 1:1.
3. The method of claim 2 , wherein the heavy component stream is separated in the hydrotreater into a hydrotreated light gas fraction stream comprising C 1 -C 4 alkanes, a hydrotreated light fraction stream comprising C 5+ alkanes, and a hydrotreated heavy fraction stream, wherein the temperature cut between the hydrotreated light fraction stream and the hydrotreated heavy fraction stream is at 280° C. to 320° C.
4. The method of claim 1 , wherein the light olefins comprise ethylene, propylene, butadiene, and mixed butenes.
5. The method of claim 1 , wherein the steam cracker operates at a temperature from 800° C. to 950° C.
6. The method of claim 1 , wherein the feed separator operates at a temperature of 200° C. to 400° C., and the SECC operates at a temperature of 550° C. to 800° C.
7. The method of claim 6 , wherein the SECC unit operates at a temperature of 600° C. to 750° C.
8. The method of claim 1 , wherein the light gas fraction has a final boiling point of less than 35° C.
9. The method of claim 1 , wherein at least 90 wt. % of the hydrocarbon material is present in the combination of the light gas fraction, the light fraction, and the heavy fraction.
10. A method for producing light olefins from a hydrocarbon feed, the method comprising:
separating the hydrocarbon feed having an American Petroleum Institute (API) gravity value above 35° into at least a light gas fraction stream comprising C 1 -C 4 alkanes, a light fraction stream comprising C 5+ alkanes, and a heavy fraction stream, wherein the temperature cut between the light fraction stream and the heavy fraction stream is at 280° C. to 320° C.; and
non-catalytically steam cracking the light gas fraction stream to produce a steam cracked effluent stream;
preheating the heavy fraction stream to a temperature of less than or equal to 250° C. by mixing the heavy fraction with steam prior to catalytically cracking the heavy fraction stream;
catalytically cracking the light fraction stream and the heavy fraction stream in the presence of steam and one or more catalysts selected from ZSM-5 and USY to produce a catalytically cracked effluent stream, wherein the weight ratio of steam to the light fraction stream and the heavy fraction stream is from 1:5 to 1:1; and
separating the steam cracked effluent stream and the catalytically cracked effluent stream to produce the light olefins;
wherein the light fraction stream has a final boiling point of less than 300° C.
11. The method of claim 10 , wherein the separating of the steam cracked effluent stream and the catalytically cracked effluent stream also yields a heavy component stream, said heavy component stream comprising cracked naphtha, light cycle oil with components having boiling points from 221° C. to 343° C., and heavy cycle oil with components having boiling points greater than 343° C.
12. The method of claim 11 , further comprising:
hydrotreating the heavy component stream to produce a hydrotreated heavy component stream; and
recycling at least a portion of the hydrotreated heavy component stream to be catalytically cracked.
13. The method of claim 10 , wherein the light olefins comprise ethylene, propylene, butadiene, and mixed butenes.
14. The method of claim 10 , wherein the non-catalytic cracking occurs at a temperature from 800° C. to 950° C.
15. The method of claim 10 , wherein the catalytic cracking operates at a temperature of 600° C. to 750° C.
16. The method of claim 10 , wherein the light gas fraction has a final boiling point of less than 35° C.
17. The method of claim 1 , wherein the one or more catalysts comprises a mixture of Y and ZSM-5 embedded with clay, alumina, and binder.
18. The method of claim 1 , wherein the light fraction stream and the heavy fraction stream are passed directly from the feed separator to the SECC.
19. The method of claim 1 , wherein preheating the heavy fraction stream to a temperature of less than or equal to 250° C. by mixing the heavy fraction with steam vaporizes at least a portion of the heavy fraction stream without cracking the same.
20. The method of claim 10 , wherein preheating the heavy fraction stream to a temperature of less than or equal to 250° C. by mixing the heavy fraction with steam vaporizes at least a portion of the heavy fraction stream without cracking the same.