Refiners boiled petroleum in an iron still to distill kerosene. Afterwards, the coke and tar where dug out. Single horizontal stills were used. The coking process could be stopped prematurely to produce a heavy lubricating oil.
Several stills were run in a series to process more fractions with the first still producing the coke.
Bubble cap distillation trays patented by Koch ushered in the modern distillation column in the tube furnace. The entire outside of the horizontal still was in direct contact with the flue gases for maximum heavy gas oil production.
Standard Oil of Indiana builds the first delayed coker. The Burton process developed by Standard Oil at Whiting, Indiana converted gas oil to gasoline with the production of petroleum coke. This thermal cracking of gas oil for the production of gasoline and diesel fuel led to the vertical coke drum. Lack of a heavy oil market in central United States led to the production of the heavy fuel oil in a delayed coker to produce more gasoline and diesel fuel.
The development of hydraulic decoking by Shell Oil at Wood River, Illinois. In delayed coking the use of pressure with heat for cracking and separating the heater from the coker and the use of two drums enabled continuous operation.
1955 to 1975
The growth of delayed cokers increases with the growth of fluid catalytic cracking and rapid decline in thermal cracking. Fluid cokers are developed but do not become as popular.
Modern Delayed Coking Process
The delayed coker is the only main process in a modern petroleum refinery that is a batch-continuous process. The flow through the tube furnace is continuous. The feed stream is switched between two drums. One drum is on-line filling with coke while the other drum is being steam-stripped, cooled, decoked, pressure checked, and warmed up. The overhead vapors from the coke drums flow to a fractionator, usually called a combination tower. This fractionator tower has a reservoir in the bottom where the fresh feed is combined with condensed product vapors (recycle) to make up the feed to the coker heater.
Based on Tutorial: Delayed Coking Fundamentals by Paul J. Ellis and Christopher A. Paul of Great Lakes Carbon Corporation of Port Arthur, TX. Download the complete article here. (PDF)
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