490 þ À5
ð Þ ¼ 485
F
The
API of the stream from the calculation for gravity is 38.8. Using this figure and
the MEABP in the lower series of curves in Fig. 14, a molecular weight of 201 is
read off.
Basic Petroleum Refining Processes
This chapter provides an introduction to some of the most common processes
included in fuel-oriented and nonenergy-oriented refineries. These processes are
only discussed here in summary form. They are treated in more detail later in
individual topics and chapters.
The Atmospheric Crude Distillation Unit
In refining the crude oil, it is first broken up into those raw stocks that are the basis
of the finished products. This breakup of the crude is achieved by separating the oil
into a series of boiling point fractions which meet the distillation requirements and
some of the properties of the finished products. This is accomplished in the crude
distillation units. Normally there are two units that accomplish this splitting up
function: an atmospheric unit and a vacuum unit.
The crude oil is first desalted (dissolved brine is removed by washing) and heated to
a predetermined temperature prior to its introduction into the atmospheric unit. This is
accomplished by heat exchange with hot products and finally by a direct fired heater.
The hot and partially vaporized crude is “flashed” in a trayed distillation tower. Here,
the vaporized portion of the crude oil feed moves up the tower and is selectively
condensed by cooled reflux streams moving down the tower. These condensates are
taken off at various parts of the tower according to their condensing temperature as
distillate side streams. The light oils not condensed in the tower are taken off at the top
of the tower to be condensed externally as the overhead product. The unvaporized
portion of the crude oil feed leaves the bottom of the tower as the atmospheric residue.
The unit operates at a small positive pressure around 5–10 psig in the overhead
drum, thus its title of “atmospheric” crude unit. Typical product streams leaving the
distillation tower are as follows:
Overhead distillate
Full-range naphtha
Gas to 380
F cut point
1st side stream
Kerosene
380–480
F cut range
2nd side stream
Light gas oil
480–610
F cut range
3rd side stream
Heavy gas oil
610–690
F cut range
Residue
Fuel oil
+690
F cut point
Full details of this unit are given in the chapter entitled “▶ Atmospheric and
Vacuum Crude Distillation Units in Petroleum Refineries.”
Introduction to Crude Oil and Petroleum Processing
33
ð Þ ¼ 485
F
The
API of the stream from the calculation for gravity is 38.8. Using this figure and
the MEABP in the lower series of curves in Fig. 14, a molecular weight of 201 is
read off.
Basic Petroleum Refining Processes
This chapter provides an introduction to some of the most common processes
included in fuel-oriented and nonenergy-oriented refineries. These processes are
only discussed here in summary form. They are treated in more detail later in
individual topics and chapters.
The Atmospheric Crude Distillation Unit
In refining the crude oil, it is first broken up into those raw stocks that are the basis
of the finished products. This breakup of the crude is achieved by separating the oil
into a series of boiling point fractions which meet the distillation requirements and
some of the properties of the finished products. This is accomplished in the crude
distillation units. Normally there are two units that accomplish this splitting up
function: an atmospheric unit and a vacuum unit.
The crude oil is first desalted (dissolved brine is removed by washing) and heated to
a predetermined temperature prior to its introduction into the atmospheric unit. This is
accomplished by heat exchange with hot products and finally by a direct fired heater.
The hot and partially vaporized crude is “flashed” in a trayed distillation tower. Here,
the vaporized portion of the crude oil feed moves up the tower and is selectively
condensed by cooled reflux streams moving down the tower. These condensates are
taken off at various parts of the tower according to their condensing temperature as
distillate side streams. The light oils not condensed in the tower are taken off at the top
of the tower to be condensed externally as the overhead product. The unvaporized
portion of the crude oil feed leaves the bottom of the tower as the atmospheric residue.
The unit operates at a small positive pressure around 5–10 psig in the overhead
drum, thus its title of “atmospheric” crude unit. Typical product streams leaving the
distillation tower are as follows:
Overhead distillate
Full-range naphtha
Gas to 380
F cut point
1st side stream
Kerosene
380–480
F cut range
2nd side stream
Light gas oil
480–610
F cut range
3rd side stream
Heavy gas oil
610–690
F cut range
Residue
Fuel oil
+690
F cut point
Full details of this unit are given in the chapter entitled “▶ Atmospheric and
Vacuum Crude Distillation Units in Petroleum Refineries.”
Introduction to Crude Oil and Petroleum Processing
33