(c)
Major recognition features of POL treating unit include:
Rows of long horizontal settlers (tanks) and vertical mixers (tanks) will be
visible.
The mixers may be of various sizes, and the smallest may be
obscured by supporting framework.
Groups of tall, large-diameter batch agitators (tanks) with curved, domed,
or stepped roofs.
NOTE: Storage tanks are a major image component of refineries.
Most refineries
contain a number of different varieties of POL storage tanks.
The function
or use of a tank can be determined by its size, shape, and location.
Use
Figure 2-5 with the following descriptions:
Flat, peaked, and domed cylindrical tanks store crude oil or partially
refined products. Crude oil storage tanks are very large, averaging 90 to
120 feet in diameter.
Pontoon and noded tanks store gasoline or other highly volatile liquids.
The floating top of the pontoon tank eliminates airspace, and therefore,
wasteful evaporation.
In the noded tank, evaporation is controlled by
Spherical, spheroidal, bullet, and blimp tanks store light gases in the
liquefied state under pressure.
The spherical and spheroidal tanks may vary
in diameter from 20 to 50 feet.
The vapor dome tank collects gases for later routing to the light ends unit.
e. Crude oil flow. This flow originates in the extraction industry at the
oil fields and extends to the storage tanks, which are located near the POL
processing facilities.
Oil fields are areas in which naturally occurring subsurface reservoirs of
petroleum are tapped for the production of crude oil.
Such fields are found
throughout the world on many different types of terrain and in offshore locations
as well.
Equipment found in oil fields the world over is remarkably similar in
design.
This facilitates the identification of an oil field as such, and the
various operations which are taking place.
Oil field equipment is identified as
being associated with one of the following four interrelated functions which are
necessary for the production of crude petroleum.
These functions include:
drilling, production, field processing, gathering and field storage.
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IT 0673
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