1. Agenda 1. Composition & Molecular Types
2. Characterization of Petroleum Products
3. Crude Oil Properties
4. Distillation Analysis
5. Exercise Problems

2. Refinery Feedstocks Crude Oil Complex mixture of hydrocarbons
Dissolved gases to non-volatiles (1000°F+ boiling material)
C1 to C90+
Composition
Element
Wt%
Carbon
84-87
Hydrogen
11-14
Sulfur
0-5
Nitrogen
0-0.2
Other elements
0-0.1

3. Crude Oil Molecular Types
Paraffins
Carbon atoms connected by single bond.
Other bonds saturated with hydrogen.
Naphthenes
Ringed paraffins (cycloparaffins).
All bonds saturated with hydrogen.
N-Butane
Cyclopentane

4. Crude Oil Molecular Types
Aromatics
Six carbon ring (multiple bonding).
All bonds are unsaturated.
Olefins
Usually not in crude oil.
Formed during processing.
At least two carbon atoms connected by double bond.
Naphthalene
Benzene
1-butene

5. Characteristics of Petroleum Products
Refinery Coke
Vacuum Resid
Atmospheric Resid
Crude Oil
Gas Oil
Jet Fuel/Diesel
Gasoline
LPG
Average Carbon Number (Atoms per Molecule)
Hydrogen/Carbon Atomic Ration

6. Characteristics of Petroleum Products
Petroleum Fractions
Hydrocarbon Range
Boiling Range (°C)
Boiling Range (°F)
Light gases
C2-C4
-90 ~ 1
-130 ~ 30
Gasoline (light and heavy)
C4-C10
-1 ~ 200
30 ~ 390
Naphtha (light and heavy)
C4-C11
-1 ~ 205
30 ~ 400
Jet fuels
C9-C14
150 ~ 225
300 ~ 490
Kerosene
C11-C14
205 ~ 225
400 ~ 490
Diesel fuel
C11-C16
205 ~ 290
400 ~ 550
Light gas oil
C14-C18
255 ~ 315
490 ~ 600
Heavy gas oil
C18-C28
315 ~ 425
600 ~ 800
Wax
C18-C26
315 ~ 500
600 ~ 930
Lubricating oil
>C25
>400
>750
Vacuum gas oil
C28-C55
425 ~ 600
800 ~ 1100
Residuum
>C55
>600
>1100

7. Crude Oil Assay Distillation Analysis
Indicates the quality of the crude oil feedstock.
Based on the amount of material that boils in a particular temperature range.
Represents expected products from crude & vacuum distillation.
Amount of data depends on laboratory analysis.
Quality Measures
Gravity, API
Characterization factor
Sulfur content, wt%
Pour point, F (C)
Carbon residue, wt%
Salt content, lb/1000 bbl
Nitrogen content, wt%
Metal content, ppm

8. Crude Oil Properties Distillation Analysis
Amount collected from batch distillation at the indicated temperature.
Most useful is TBP (True Boiling Point).
Standardized tests: ASTM D86, D1160, …etc.
API Gravity
A measure of gravity or density.
Arabian crudes are classified as follows:
Arabian Heavy (29 API and less)
Arabian Medium (29-32 API)
Arabian light (32-34 API)
Arabian Extra Light (36-41 API)
Arabian Super Light (49-52 API)

9. Oil Classification Using Assay Data
Key Fractions, °API
No. 1 (760 mmHg) °F
No. 2 (40 mm Hg) °F
Paraffin
40 °
30 °
Paraffin, intermediate
20-30 °
Intermediate, paraffin
33-40 °
Intermediate
Intermediate, naphthene
20 °
Naphthene, intermediate
33 °
Naphthene
<33 °
<20 °

10. Crude Oil Characterizations
Paraffinic (West Texas)
Little heavy aromatic material (asphaltic).
Good for paraffin wax manufacture.
Quality Lube stocks.
High grade kerosene.
Naphthenic (Louisiana)
High quality gasoline (octane).
Poor lubes & kerosene.
Aromatic (Maya)
High quality gasoline & asphalt.
High levels of poisons; sulfur & nitrogen.
Residue is asphaltic.

11. Crude Oil Properties

12. Crude Oil Properties Characterization Factor Watson factor (UOP)
Indication of crude oil aromaticity and paraffinicity.
Less than 10 is highly aromatic.
Up to 15 is highly paraffinic.
Correlation Index (U. S. Bureau of Mines)
Individual fractions from crude oils.
Straight-run paraffins have a CI of 0 and benzene have a CI value of 100.

13. Crude Oil Properties

14. Crude Oil Properties Sulfur Content
Takes the form of hydrogen sulfide (H2S), mercaptans, sulfides, disulfides.
Odorous and toxic.
“Sour” vs. “sweet” — ~0.5 wt% cutoff.
Restrictions on sulfur in final products.
Nitrogen Content
Takes many forms (e.g. Cyanides)
Odorous and corrosive.
In heavy gas oil, acts as an inhibitor to FCCU and HCU catalyst.
Usually tolerate up to 0.25 wt%.

15. Crude Oil Properties Metals Content
Arsenic, nickel, vanadium, copper, …etc.
Poison catalysts.
Nickle and vanadium affect FCCUs and HCU.
Carbon Residue
Carbon residues from specific ASTM tests.
D524 — Ramsbottom.
D189 — Conradson (CCR).
Related to asphalt and lubricating oil content.
Pour Point
Rough indicator of paraffin vs. aromatic content.
Specific flow test.
The lower the pour point the lower the paraffin content.
Salt Content
Generally associated with emulsified water.

16. Sample Crude Oil Assay

17. Distillation Analysis
ASTM D86
Gasoline, turbine fuels, naphtha, kerosene, gas oil and distillate fuel oils.
Atmospheric pressure.
No hotter than 650°F to minimize cracking.
Correlations to correct to TBP basis.

18. Distillation Analysis
ASTM D1160
Heavy petroleum products (650°F+).
Vacuum conditions — 10 to 40 mmHg.
Correlations to correct to atmospheric.

19. Simulated Distillation Analysis
ASTM D2892 & D5236
This method uses a 15 plate column operating under a reflux ration of 5:1.
Starts at atmospheric pressure.
Maximum temperature of 650 F.
Switch to ASTM D5236 at o.1 mmHg pressure.
Maximum temperature of 1000 F.
TBP temperatures — wt% basis

20. Distillation Curve & Fractions

21. Distillation Curve & Fractions
Temperature, F
Volume percent vaporized

22. Assay Data Manipulation
Boiling Point Manipulation
Correct temperatures to atmospheric pressure.
Correct temperatures to TBP basis.
Put onto cumulative basis for the whole crude.
Cumulative Yield Curve
“S” shaped curve — yield vs. boiling point.
Linearized using Gaussian normal probability functions.
Standardized Cut Points
Volume increments.
Cut points corresponding to crude tower products.
Temperatures associated with the lightest pure components.

23. Assay Data Manipulation
Properties for Fractions
Properties inferred from measured trends.
» Relative density / specific gravity / API gravity
» Sulfur content
» Carbon residue
Properties from correlations
» Molecular weight / molar mass
» Critical properties & acentric factor
» Heat of combustion ^ ^

24. Assay Data Manipulation
Adjusting Temperature for Pressure
Equation form of Maxwell-Bonnell charts (1955)

25. Interconvert D86 & TBP Temperature
Vol% a b
IBP
0.9167
1.0019 10
0.5277
1.0900 30
0.7492
1.0425 50
0.8920
1.0176 70
0.8008
1.0226 90
0.9490
1.0110 95
0.8705
1.0355

26. Interconvert D1160 & TBP Temp.
D1160 temperatures at 10 mm Hg are converted to TBP temperatures at 10 mm Hg — graphical method.
D1160 temperatures at 50% & higher equal to the TBP temperatures.
0% to 10%, 10% to 30%, & 30% to 50% D1160 temperature differences converted to TBP temperature differences.
Vol% Distilled Range a b c d
Max ∆T
0%-10%
E-2
E-5
E-8
144 °F
10%-30%
30%-50%
E-3
E-5
E-8
180 °F

27. Interconvert D1160 & TBP Temp.

28. Average Boiling Point for a Fraction
Five types are defined in the API Technical Data Book
Volume average boiling point
Mass average boiling point
Molar average boiling point
Cubic average boiling point
Mean average boiling point
Use either mid-boiling point or boiling point at mid-cumulative amount