Agenda
1. Composition & Molecular Types 1. Composition & Molecular Types
2. Characterization of Petroleum Products2. Characterization of Petroleum Products
3. Crude Oil Properties 3. Crude Oil Properties
4. Distillation Analysis 4. Distillation Analysis
5. Exercise Problems 5. Exercise Problems
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
Crude Oil Molecular Types
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
Crude Oil Molecular Types
BenzeneNaphthalene
1-butene
• 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.
Characteristics of Petroleum Products
Refinery Coke
Vacuum Resid
Atmospheric Resid
Crude Oil
Gas Oil
Jet Fuel/Diesel
Gasoline
LPGAverage Carbon Number (Atoms per Molecule)
Hyd
rog
en/C
arb
on
Ato
mic
R
atio
n
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
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
Crude Oil Properties
API 141 5
131 5.
.
•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)
Oil Classification Using Assay Data
Key Fractions, °API
No. 1 (760 mmHg)482-527 °F
No. 2 (40 mm Hg)527-572 °F
Paraffin 40 ° 30 °
Paraffin, intermediate 40 ° 20-30 °
Intermediate, paraffin 33-40 ° 30 °
Intermediate 33-40 ° 20-30 °
Intermediate, naphthene 33-40 ° 20 °
Naphthene, intermediate 33 ° 20-30 °
Naphthene <33 ° <20 °
Crude Oil Characterizations
• Paraffinic (West Texas)•Little heavy aromatic material (asphaltic).•Good for paraffin wax manufacture.•Quality Lube stocks.•High grade kerosene.
• Naphthenic (Louisiana)•Little heavy aromatic material (asphaltic).•High quality gasoline
(octane).•Poor lubes & kerosene.
•Aromatic (Maya)•High quality gasoline
& asphalt.•High levels of
poisons; sulfur & nitrogen.•Residue is asphaltic.
Crude Oil Properties
KwT
b
13
•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.
8.4567.473552,87
bT
CI
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%.
Crude Oil Properties
•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.
•Metals Content•Arsenic, nickel, vanadium, copper, …etc.•Poison catalysts.•Nickle and vanadium affect FCCUs and
HCU.
Distillation Analysis
•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.
ASTM D86
Distillation Analysis
•Heavy petroleum products (650°F+).
•Vacuum conditions — 10 to 40 mmHg.
•Correlations to correct to atmospheric.
ASTM D1160
Simulated Distillation Analysis
•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
ASTM D2892 & D5236
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.
Assay Data Manipulation
M T T TB B B 20 486 0 0001165 7 78712 0 00115821 26007 4 98308. exp ( . . . ). .
• 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
H G G G 16792 54 5 0 217 0 00192 3. . .^
H G G G 16792 54 5 0 217 0 00192 3. . .^
Assay Data Manipulation
•Equation form of Maxwell-Bonnell charts (1955)
•Adjusting Temperature for Pressure
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
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% 2.23652561 -1.39334703E-2 3.6358409E-5 1.433117E-8 144 °F
10%-30%30%-50%
1.35673984 -5.4126509E-3 2.9883895E-5 -6.007274E-8 180 °F
Average Boiling Point for a Fraction
Volume average boiling point
Mass average boiling point
Molar average boiling point
Cubic average boiling point
Mean average boiling point
Five types are defined in the API Technical Data Book
Use either mid-boiling point or boiling point at mid-cumulative amount