3.Fuel Oil

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Petroleum Process Engineering, 2010-2011 4

FUEL OIL

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Crude Oil - Introduction

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Introduction

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Strictly speaking, the term Fuel Oil or

Mazot refers to a furnace fuel that is

obtained as a residual petroleum fraction

coming from the bottom of theatmospheric tower (AD tower)

Such fraction is also known as the long

residue

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Introduction

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Refineries deal differently with such

fraction as follows:

Taken as a product from the

the AD tower

Supplied to the Vacuum

tower for further

fractionation For this part well

deal with Fuel Oil as an AD tower

product

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Uses/Applications

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1. Domestic:Central Heating, where the

most common method of heat generation

involves the combustion

of fossil fuelin a furnace.

The resultant heat then

gets distributed in which

the central heating system provides

warmth to the whole

interior of a building
http://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Fossil_fuel

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Uses/Applications

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2. Industrial:steam generation in which the

fuel oil is used in heating furnaces

3. In Transportation: Used in Ships and

known as Bunker fuel which stands forthe heaviest type of fuel oil

4. Crackedto produce

more valuable products

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Refining Processes

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Fuel oil is a heavy cheap fraction that has

limited uses, thus it is not economic to

invest in refining the oil to improve its

properties. Consequently, it is: Sold as it is

Or blended with other species of fuel oil

having better specifications (like blending ahigh sulfur content oil with another having a

low sulfur content)

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Specifications

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1. Viscosity

Fuel oil is highly viscous, that it is difficult to

pump throughout a fuel system and fuel

nozzles In order to fix such problem, some fuel

systems contain steam that is used to heat

fuel oil and thus reduce its viscosity

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Specifications

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1. Viscosity

Typical viscosities for different types of fuel oil

over a range of temperatures is shown below

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1. Viscosity

Other mechanical or intergrated

mechanical/thermal techniques are used to

push (Atomize) the oil through nozzles tomake it easily and smoothly burnt.

Atomization occurs by forcing fuel through a

small jet (opening) under high pressure to

break it into a fine misted spray

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Specifications

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1. Viscosity

There is a number of atomization techniques;

Blast Burner

Rotary Cup Burner Viscosity specs for fuel oil:

1500 sec. Red I in winter

2000 sec. Red I in summer

Would these numbers be different in another

country? Why?

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Specifications

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2. Carbon Residue

Measures the liable extent of deposits

remaining upon burning

A high carbon residue is not appreciatedsince it deposits on burner nozzles and might

eventually result in plugging such nozzles

Since fuel oil is not to be

refined, such property is

enhanced by blending with

other species having lower

carbon residues

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Specifications

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2. Carbon Residue

The Conradson apparatus is used to measure

the carbon residue (we shall experience such

experiment in the lab.) The principle is based on simply weighting a

sample of the oil, then burning the sample to

complete combustion, the %weight remaining

is the carbon residue

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Specifications

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3. Pour Point

In many cases, the pour point spec for F.O is

determined based on the minimum weather

conditions. Yet, although it is a heavy fraction, it is not

important for fuel oil.

Bonus Question; Why?!

Because fuel oil is heated anyway throughout its

paths to reduce viscosity

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Specifications

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4. Flash Point

By default, flash point is a property for

light fractions, yet it is measured for F.O,

where it should commonly be > 150 F Bonus Question: Why do you think it is

important to measure it for F.O.?

Because if the distillation process is not proper,

some lighter fractions might escape with the F.O.

cut, and since these fractions are of a higher

value, it will not be economic to lose it with the

cheap F.O. fraction

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Specifications

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5. Calorific Value

Calorific Value is an important property for

F.O. since it is used as a fuel

Generally, the heavier the fuel, the higher theC/H ratio and the lower the calorific value

and the price

Consequently, F.O -being heavy- has a low

calorific value ranging from18000 to 19000

Btu/lb

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Specifications

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5. Calorific Value

Calorific Value is measured using a

calorimeter, and the table below shows how

it graduates as the C/H ratio increases

Type of fuel Calorific value Btu / lb

Hydrogen 61,000

Gasoline

20,000

Diesel 19,300

Fuel oil 18,000

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Specifications

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6. Sulfur Content

Sulfur content is an important spec for all

fossil fuels, why?

As a rule of thumb; For straight run fractions,the heavier the fraction, the higher the sulfur

content. And since fuel oil comes from the

bottom of the AD, it is expected to have a

higher sulfur content compared to otherlighter fractions

The specification for the F.O. sulfur content is

4%

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3.Fuel Oil