(d)
Major recognition features of delayed coking unit (Figure 2-42) include:
Pipe furnace
Fractionating tower
Two or three tall, dark, cylindrical coke drums standing side by side
Possibly drill derricks atop coke drums, or drilling rig located beneath
drums and hidden from view
Stockpiles of black petroleum coke or hopper cars loaded with coke.
Figure 2-42. Delayed Coking Unit.
(9)
Treating.
Gasoline, kerosene, diesel oil, and fuel oil still contain
undesirable constituents when they come out of the fractionating column or cracking
unit. The treating process uses chemical reagents to remove these impurities. The
liquid petroleum product and the reagents are mixed together in a tank.
The
chemicals react with the impurities to form solid or semisolid particles which
settle to the bottom. The purified fuel can be drained off the top of the tank.
(a)
Two types of treating units are the continuous and batch units. In the
continuous treatment units, the fuel and chemical reagents are mixed in a small
vertical tank (a mixer)(Figure 2-43), and piped into a long horizontal tank (a
settler) where the impurities are allowed to precipitate (Figure 2-44).
(b)
In the batch treatment method, a tall, large-diameter tank is used for
both the mixing and settling operations.
In the tanks, called batch agitators,
chemical reagents and fuel are mixed and the impurities are allowed to settle
(Figure 2-45).
55 IT 0673
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