Hydrocarbon thermal cracking using atmospheric residuum

1 . In a method for thermally cracking a hydrocarbonaceous feed in at least one cracking furnace wherein said feed is first subjected to a vaporization step in which at least a preponderance of said feed is vaporized and the vapors thus formed are passed to said at least one cracking furnace as the feed for said furnace, the improvement comprising providing cracking feed composed in significant amount of at least one residuum formed from the atmospheric thermal distillation of crude oil, and subjecting said atmospheric residuum feed to said vaporization step.

2 . The method of claim 1 wherein said vaporization step employs at least first and second vaporization zones, said first vaporization zone receives said residuum feed and separates gaseous materials associated with said residuum feed as received and any additional gaseous materials formed in said first vaporization zone, said separated gaseous materials are passed from said first vaporization zone to said at least one cracking furnace as feed therefore, said second vaporization zone receives from said first vaporization zone liquid residuum feed that was not vaporized in said first vaporization zone and subjects said liquid residuum feed to at least one of heating and mild cracking in said second vaporization zone until a significant amount of said liquid residuum feed in said second zone is vaporized, and the gaseous materials formed in said second zone are removed therefrom and passed to said at least one cracking furnace as feed therefore.

3 . The method of claim 2 wherein said gaseous materials from said first and second vaporization zones are passed to the same cracking furnace.

4 . The method of claim 1 wherein said atmospheric residuum feed is composed of a mixture of at least two differing residua.

5 . The method of claim 1 wherein said atmospheric residuum feed has a boiling range of from about 600 F to its boiling end point.

6 . The method of claim 1 wherein there is added to said residuum feed to said vaporization step at least one of light gasoline, at least one naphtha fraction, natural gasoline, and condensate.

7 . The method of claim 6 wherein said light gasoline boils in the range of from about the boiling point of pentane to about 158 F, said naphtha fraction boils in the range of from about 158 to about 350 F, and said condensate boils in a range of from about 100 to about 650 F.

8 . The method of claim 6 wherein said naphtha fraction is composed of at least one of light naphtha, medium naphtha, and heavy naphtha.

9 . The method of claim 8 wherein said light naphtha boils in the range of from about 158 to about 212 F, said medium naphtha boils in the range of from about 212 to about 302 F, and said heavy naphtha boils in the range of from about 302 to about 350 F.

10 . The method of claim 1 wherein said cracking feed contains at least about 20 wt. % atmospheric residuum based on the total weight of said feed.