초록

The coke yield from a delayed coker is minimized by substituting a lower boiling range material for a part of the conventional recycle.

대표청구항 ▼

In a delayed coking process carried out in a coker unit comprised of a coker furnace, a coke drum and a coker fractionator, wherein coker feedstock and recycle material are heated to coking temperature in said furnace and then passed to said coke drum where coke and overhead vapors are formed, where

In a delayed coking process carried out in a coker unit comprised of a coker furnace, a coke drum and a coker fractionator, wherein coker feedstock and recycle material are heated to coking temperature in said furnace and then passed to said coke drum where coke and overhead vapors are formed, wherein said overhead vapors are passed to said fractionator, wherein a portion of said overhead vapors are condensed and combined with said feedstock as heavy recycle, wherein the amount of said overhead vapors condensed is sufficient to provide good fractionator operation and sufficient to provide enough heavy recycle to effectively prevent coke formation on the tubes of said furnace, and wherein the coke yield is higher than is desired, the improvement comprising: operating with an amount of heavy recycle that is not sufficient to effectively prevent coke formation on the furnace tubes, and adding to said feedstock as additional recycle a distillate hydrocarbon material having a boiling range which is at least in part lower than the boiling range of said heavy recycle, said distillate hydrocarbon material being added in an amount which, when combined with said heavy recycle, is effective to prevent coke formation on the tubes of said furnace, whereby coke formation on the tubes of said furnace is effectively prevented, the yield of liquid products from the process is increased, and the coke yield from the process is decreased.