From Fig. 3, curve B ASTM end point = 432–13
F = 419
F
From Fig. 3, curve G ASTM 90 % point = 430–24
F = 406
F
These two points are plotted in Fig. 4 and a straight line drawn through them to
define the probable ASTM distillation of the cut. This is plotted linearly in Fig. 5
and can be seen to compare well with laboratory results of the actual product from a
crude distillation unit.
Developing the TBP Curve and the Equilibrium Flash Vaporization
(EFV) Curve from the ASTM Distillation Curve
Using a product ASTM distillation curve developed as shown above, the TBP curve
is developed as follows:
Converting the Product ASTM Distillation to TBP
Most crude distillation units take a full-range naphtha cut as the overhead product.
This cut contains all the light ends, ethane through pentanes, in the crude and of
course the heavier naphtha cut. All the light ends are in solution; therefore, it is not
possible to prepare a meaningful ASTM distillation on this material directly. Two
routes can be adopted in this case: the first is to take naphtha samples of the heavy
naphtha and debutanized light naphtha from downstream units. Alternatively the
sample can be subject to light end analysis in the lab such as using POD apparatus
(Podbielniak), a gas chromatograph, or and carrying out an ASTM distillation on
the stabilized sample. It is the third route that is chosen for this case.
There are two well-proven methods for this conversion. The first is by Edmister
and given in his book Applied Hydrocarbon Thermodynamics and the second by
Lab Data
420
400
380
360
340
0
10
20 30
40
50
% Vol
60
70 80 90 FBP
Calculated
Fig. 5 Comparison between
calculated ASTM curve and
lab data
Introduction to Crude Oil and Petroleum Processing
19
F = 419
F
From Fig. 3, curve G ASTM 90 % point = 430–24
F = 406
F
These two points are plotted in Fig. 4 and a straight line drawn through them to
define the probable ASTM distillation of the cut. This is plotted linearly in Fig. 5
and can be seen to compare well with laboratory results of the actual product from a
crude distillation unit.
Developing the TBP Curve and the Equilibrium Flash Vaporization
(EFV) Curve from the ASTM Distillation Curve
Using a product ASTM distillation curve developed as shown above, the TBP curve
is developed as follows:
Converting the Product ASTM Distillation to TBP
Most crude distillation units take a full-range naphtha cut as the overhead product.
This cut contains all the light ends, ethane through pentanes, in the crude and of
course the heavier naphtha cut. All the light ends are in solution; therefore, it is not
possible to prepare a meaningful ASTM distillation on this material directly. Two
routes can be adopted in this case: the first is to take naphtha samples of the heavy
naphtha and debutanized light naphtha from downstream units. Alternatively the
sample can be subject to light end analysis in the lab such as using POD apparatus
(Podbielniak), a gas chromatograph, or and carrying out an ASTM distillation on
the stabilized sample. It is the third route that is chosen for this case.
There are two well-proven methods for this conversion. The first is by Edmister
and given in his book Applied Hydrocarbon Thermodynamics and the second by
Lab Data
420
400
380
360
340
0
10
20 30
40
50
% Vol
60
70 80 90 FBP
Calculated
Fig. 5 Comparison between
calculated ASTM curve and
lab data
Introduction to Crude Oil and Petroleum Processing
19