PETE 203: Properties of oil

Prepared by: Mr. Brosk Frya Ali

Koya University, Faculty of Engineering,

Petroleum Engineering Department

2013 – 2014

Lecture no. (5): Crude oil Refining

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The boiling range gives information on the composition, the

properties, and the behavior of petroleum and derived

products during storage and use.

13. Distillation (True Boiling Point test TBP):

The distillation tests give an indication of the types of products

and the quality of the products that can be obtained from

petroleum.

The tests are used to compare different petroleum types

through the yield and quality of the residuum fraction.

A standard laboratory technique used to predict the refining

qualities of crude petroleum; gives distillation cuts for gasoline,

kerosene, distillate (diesel) fuel, etc.

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Volatility is the major determinant of the tendency of

hydrocarbon mixtures to produce potentially explosive vapors.

The mainly products of crude oil distillation

Product Boiling range oC

Gas < 15.5

Gasoline (light naphtha) 15.5 - 149

Kerosene (medium naphtha) 149 - 232

Gas oil 232 – 343

Light vacuum gas oil 343 – 371

Heavy vacuum gas oil 371 – 556

Residuum > 566

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Distillation Column

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Bubble cap tray consists of a

slotted cap on a central riser.

The gas flows up through the riser, reverse flow under the cap,

passes downward through the annulus between riser and cap, and

finally passes into the liquid through a series of openings or

"slots" in the lower side of the cap.

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A key result from a distillation test is the boiling point curve,

that is, the boiling point of the oil fraction versus the fraction of

oil vaporized.

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14. Octane number:

The octane number is a measure of the knocking characteristics

of a fuel in a laboratory gasoline engine.

We determine the octane number of a fuel by measuring its

knocking value compared to the knocking of a mixture of n-

heptane and isooctane or 2-2-4-trimethylpentane (224TMP).

A mixture of 30% heptane and 70% isooctane has an octane

number of 70.

Knocking is explosion caused by its premature burning in the

combustion chamber.

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Properties of oil Lecture NO.5

14. Octane number:

The octane number of n-heptane is 0 while for iso-octane is100, by

definition.

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15. Cetane number:CN

The cetane number is a measurement of the combustion quality

of diesel fuel during compression ignition. It is a significant

expression diesel fuel.

In short, the higher the Cetane number the more easily the fuel

will combust in a compression setting.

Normal modern highway diesels run best with a fuel rated

cetane number between 45 and 55.

The optical method for determining cetane requires the use of

an industry standard test engine equipped with accepted

instrumentation and operated under specific conditions.

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The disadvantages are:

1. The high purchase cost ($500,000 plus), ongoing

maintenance, and operating cost

2. Requirement for trained staff and expertise for operation

and maintenance

3. Poor reliability and accuracy of results

Many agencies rely on standards developed by ASTM

International to accurately calculate cetane index. ASTM

D4737 provides a formula based on four fuel variables.

They include the density of the fuel as well as the recovery

temperature at three cooling intervals.

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Cetane Index Equation by ASTM D4737

Properties of oil Lecture NO.5