separation process. The temperature for this desalting process (usually around
220–250
F) must be accommodated in the crude feed preheating.
An Example in the Design of an Atmospheric Crude Oil
Distillation Tower
This example is confined to the design of the main fractionator and the associated
stripper column. It is based on the processing of 30,000 BPSD of Kuwait crude
providing the following products:
Overhead full-range naphtha
Gas to 375
F
First side stream kerosene
375–480
F
Second side stream light gas oil
480–610
F
Third side stream heavy gas oil
610–680
F
The distillation specifications shall be as follows:
• The ASTM end point of the naphtha shall not exceed 400
F.
• The difference between the ASTM 95 % point of the naphtha and the 5 % point
of the kerosene shall be at least 25
F.
• The difference between the ASTM 95 % point of the kerosene and the 5 % point
of the light gas oil shall be À10
F (10
overlap).
• The ASTM end point of the light gas oil shall not be greater than 620
F.
• The difference between the ASTM 95 % point of the light gas oil (LGO) and the
5 % point of the heavy gas oil (HGO) shall not exceed – 35
F (35
overlap).
• The FBP of the TBP shall not exceed 710
F and a Conradson carbon content of
8.0 % maximum.
Developing the Material Balance
The crude TBP and SG curves are given in Figs. 15 and 16, respectively. The TBP curve
is divided into the distillate product cuts and also into narrow boiling point components.
The ASTM curves for the cuts are developed from the product cut points and
probability paper. These are converted to TBP using the “Edmister” method as
shown in Table 1.
These values are plotted on Fig. 17 and the narrow range components indicated
for each of the product cuts. Note that the front end of the naphtha is the front end of
the whole crude, so only the last segment of the cut is required in this calculation.
The cut characteristics are shown in Table 2.
Overflash
Cut range 690–725 (3 %vol on crude)
SG at 60
F
0.891
Mol wt
295
The complete material balance can now be written as shown in Table 3.
158
D.S.J. Jones
220–250
F) must be accommodated in the crude feed preheating.
An Example in the Design of an Atmospheric Crude Oil
Distillation Tower
This example is confined to the design of the main fractionator and the associated
stripper column. It is based on the processing of 30,000 BPSD of Kuwait crude
providing the following products:
Overhead full-range naphtha
Gas to 375
F
First side stream kerosene
375–480
F
Second side stream light gas oil
480–610
F
Third side stream heavy gas oil
610–680
F
The distillation specifications shall be as follows:
• The ASTM end point of the naphtha shall not exceed 400
F.
• The difference between the ASTM 95 % point of the naphtha and the 5 % point
of the kerosene shall be at least 25
F.
• The difference between the ASTM 95 % point of the kerosene and the 5 % point
of the light gas oil shall be À10
F (10
overlap).
• The ASTM end point of the light gas oil shall not be greater than 620
F.
• The difference between the ASTM 95 % point of the light gas oil (LGO) and the
5 % point of the heavy gas oil (HGO) shall not exceed – 35
F (35
overlap).
• The FBP of the TBP shall not exceed 710
F and a Conradson carbon content of
8.0 % maximum.
Developing the Material Balance
The crude TBP and SG curves are given in Figs. 15 and 16, respectively. The TBP curve
is divided into the distillate product cuts and also into narrow boiling point components.
The ASTM curves for the cuts are developed from the product cut points and
probability paper. These are converted to TBP using the “Edmister” method as
shown in Table 1.
These values are plotted on Fig. 17 and the narrow range components indicated
for each of the product cuts. Note that the front end of the naphtha is the front end of
the whole crude, so only the last segment of the cut is required in this calculation.
The cut characteristics are shown in Table 2.
Overflash
Cut range 690–725 (3 %vol on crude)
SG at 60
F
0.891
Mol wt
295
The complete material balance can now be written as shown in Table 3.
158
D.S.J. Jones