Claims
- 1. In a process for the delayed coking of a coking feedstock wherein a coking feedstock is heated in a coking heater and introduced into a coke drum, and, after filling of the coke drum to the desired level, the coke drum is taken off-stream by discontinuing introduction of coking feedstock, the improvement comprising:
- operating the coke drum at a temperature of from 415.degree. C. to 455.degree. C. prior to taking the coke drum off-stream; and subsequent to taking the coke drum off-stream, heating the contents of the off-stream coke drum at a temperature which is at least 10.degree. C. greater than the prior coking temperature and which is from 450.degree. C. to 500.degree. C., said heating being effected for a time sufficient to provide a coke having a volatile combustible matter content of at least 4% and no greater than 10%, all by weight.
- 2. The process of claim 1 wherein the heating temperature is at least 15.degree. C. greater than the prior coking temperature.
- 3. The process of claim 2 wherein the coking temperature is from 420.degree. C. to 450.degree. C.
- 4. The process of claim 3 wherein the heating temperature is at least 460.degree. C. and no greater than 480.degree. C.
- 5. The process of claim 1 wherein the off-stream coke drum is heated by passing a heated non-coking vapor through the contents thereof.
- 6. The process of claim 5 wherein the coking feedstock is pretreated by heat soaking at a temperature of from 230.degree. C. to 315.degree. C. to polymerize unsaturates in the feedstock.
- 7. The process of claim 6 wherein said heat soaking is effected in the presence of at least 30 ppm of dissolved sulfur.
- 8. The process of claim 5 wherein the feedstock is pretreated by heating to effect thermal cracking thereof at a final temperature of from 450.degree. C. to 595.degree. C.
- 9. The process of claim 7 wherein subsequent to the heat soaking the feedstock is pretreated by heating to effect thermal cracking thereof at a final temperature of from 450.degree. C. to 595.degree. C.
- 10. The process of claim 9 wherein the heating temperature is at least 15.degree. C. greater than the prior coking temperature.
- 11. The process of claim 10 wherein the coking temperature is from 420.degree. C. to 450.degree. C.
- 12. The process of claim 11 wherein the heating temperature is at least 460.degree. C. and no greater than 480.degree. C.
- 13. A process for producing needle coke from a coking feedstock, comprising:
- heat soaking the feedstock at a temperature of from 230.degree. C. to 315.degree. C. to polymerize unsaturates;
- heating the heat-soaked feedstock to effect thermal cracking thereof at a final temperature of from 450.degree. C. to 595.degree. C.;
- separating non-crystalline substances and heavy components to produce a pitch free feed;
- heating pitch free feed in a coking heater and introducing the heated pitch free feed into a coking drum operated at a temperature of from 415.degree. C. to 455.degree. C.,
- taking the coke drum off-stream after filling thereof to a desired level by discontinuing introduction of the pitch free feed; and
- heating the contents of the off-stream coke drum at a temperature which is at least 10.degree. C. greater than the prior coking temperature and which is from 450.degree. C. to 500.degree. C., said heating being effected for a time sufficient to provide a coke having a volatile combustible matter content of at least 4% and no greater than 10%, all by weight.
- 14. The process of claim 13 wherein the heating temperature is at least 15.degree. C. greater than the prior coking temperature.
- 15. The process of claim 14 wherein the coking temperature is from 420.degree. C. to 450.degree. C.
- 16. The process of claim 15 wherein the heating temperature is at least 460.degree. C. and no greater than 480.degree. C.
- 17. The process of claim 16 wherein the off-stream coke drum is heated by passing a heating non-coking vapor through the contents thereof.
- 18. A process for producing needle coke from a feedstock containing at least one member selected from the group consisting of pyrolysis fuel oils, lube oil extracts, hydrodesulfurized lube oil extracts, cataytic cracker decant oils and thermally cracked tars, comprising:
- separating non-crystalline substances and heavy components to produce a pitch free feed;
- heating pitch free feed in a coking heater and introducing the heated pitch free feed into a coking drum operated at a temperature of from 415.degree. C. to 455.degree. C.,
- taking the coke drum off-stream after filling thereof to a desired level by discontinuing introduction of the pitch free feed; and
- heating the contents of the off-stream coke drum at a temperature which is at least 10.degree. C. greater than the prior coking temperature and which is from 450.degree. C. to 500.degree. C., said heating being for a time sufficient to provide a coke having a volatile combustible matter content of at least 4% and no greater than 10%, all by weight.
- 19. The process of claim 18 wherein the heating temperature is at least 15.degree. C. greater than the prior coking temperature.
- 20. The process of claim 19 wherein the coking temperature is from 420.degree. C. to 450.degree. C.
- 21. The process of claim 20 wherein the heating temperature is at least 460.degree. C. and no greater than 480.degree. C.
- 22. The process of claim 21 wherein the off-stream coke drum is heated by passing a heated non-coking vapor through the contents thereof.
- 23. The process of claim 1 wherein the off-stream coke is heated for a time period of from 4 hours to 24 hours.
- 24. The process of claim 13 wherein the off-stream coke is heated for a time period of from 4 hours to 24 hours.
- 25. The process of claim 18 wherein the off-stream coke is heated for a time period of from 4 hours to 24 hours.
Parent Case Info
This application is a continuation of U.S. application Ser. No. 06/348,921, filed Feb. 2, 1982, now abandoned, which in turn is a continuation-in-part of U.S. application Ser. No. 214,378 filed on Dec. 5, 1980 abandoned.
US Referenced Citations (12)
Foreign Referenced Citations (1)
Number |
Date |
Country |
7411601 |
Oct 1970 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
348921 |
Feb 1982 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
214378 |
Dec 1980 |
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