Delayed coking process
First Claim
1. In a delayed coking process in which a heavy oil coker feedstock is heated to an elevated coking temperature in a furnace and the heated feedstock is subsequently subjected to delayed coking in a coker drum under superatmospheric pressure and the vaporous coking products are removed from the drum and passed to a coker fractionator from which a bottoms fraction is removed,the improvement comprising coking a feed without the addition of the bottoms fraction from the fractionator and adding to the feed to the coker drum a lower boiling hydrocarbon diluent having an end boiling point of not more than 450°
- C., the lower boiling hydrocarbon diluent being added to the heated feedstock after the feedstock has passed through the furnace.
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Accused Products
Abstract
A delayed coking process having improved liquid yield and liquid product distribution relative to coke yield is characterized by the absence of heavy recycle. The coker feedstock is heated in the coker furnace and led to the coker drums where coking takes place and the vaporous effluence are passed to a fractionator from which the heavy gas oil fraction is removed as product. Process heat is conserved by indirect heat exchange of the feedstock with the coking products prior to the feedstock entering the coking furnace. A further improvement in liquid yield and selectivity is obtained by adding a solvent or diluent to the feedstock and this may be either a hydrocarbon fraction such as a coker distillate, a light gas oil or another fraction having an end point below 450° C.; in addition, it may be used in conjunction with a reactive or nonreactive gas such as nitrogen, steam, hydrogen or hydrogen sulfide.
79 Citations
20 Claims
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1. In a delayed coking process in which a heavy oil coker feedstock is heated to an elevated coking temperature in a furnace and the heated feedstock is subsequently subjected to delayed coking in a coker drum under superatmospheric pressure and the vaporous coking products are removed from the drum and passed to a coker fractionator from which a bottoms fraction is removed,
the improvement comprising coking a feed without the addition of the bottoms fraction from the fractionator and adding to the feed to the coker drum a lower boiling hydrocarbon diluent having an end boiling point of not more than 450° - C., the lower boiling hydrocarbon diluent being added to the heated feedstock after the feedstock has passed through the furnace.
- View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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7. A process according to clam 1 in which the feedstock has a gravity of less than 12 °
- API and a Conradsen Carbon Residue greater than 10.0.
Specification