Chemical composition of Bunker C fuel oil (Oil N¦ 6) 2

[21121956]

Hello everybody

I have made my best effort (without any result) to gather information regarding with the chemical composition of the Bunker C fuel oil; in orden to achieve some combustion calculations and related subjects.

Can somebody give me advise on this matter?

 

[ctmtwilliams]

I found the following link along with others on Google:

http://www.labo-analytika.com/html/bunker_c_spec.html

 

[25362]

Chemical compositions of Bunker C vary greatly. Refer to thread794-132167. I've given therein a typical composition of a Mexican fuel, which I repeat here:

C: 82.8, H:12.19, O:2.15, S:2.8, in mass %. The rest is ash.

Some additional information:

The theoretical air needed in kg/1000 kcal of LHV is about 1.4. Normal conditions: 273.15 K, and 1 atm absolute.

The densities at normal conditions of the main components of the flue gases is:

CO₂: 1.975 kg/m³
SO₂: 2.87 kg/m³
H₂O: 0.81 kg/m³
N₂: 1.255 kg/m³
air: 1.294 kg/m³
O₂: 1.435 kg/m³
flue gas: 1.305-1.31 kg/m³

 

[jmw]

Try visiting any major fuel oil suppliers web site as they usuaally give typical breadowns of their fuels.
You might also look under marine fuels.
There are a lot of sites that detail the required fuel properties and their significance.
e.g.

http://www.viswalab.com,

http://www.IBIA.com,

and at

http://www.cimac.com

you will find reports from the fuels working group who have been working on the new ISO 8217 standard for marine fuel oils.

JMW

http://www.ViscoAnalyser.com

 

[rmw]

There was a thread a couple of years ago that got into the topic of all the stuff that is now found (or not found) in what has always been referred to as #6 Fuel Oil. Do a search on this site.

rmw

 

[0707]

No.6 Fuel oil will depend on crude oil origin, so it will be very difficult to have a typical composition. A no.6 fuel oil from a sweet crude will be very different from a sour crude origin.


“No. 6 fuel oil, sometimes called residual, Bunker C, vacuum bottoms, or reduced crude is produced by many methods, but basically, it is the residue left after most of the light volatile products have been distilled from the crude. It is a very heavy oil, with a viscosity ranging from 900 to 9000 Saybolt Universal Secondary (SUS) at 100°F. Thus it can be used only in installations with heated storage tanks and with a recirculating piping return back to the tank in order to circulate hot oil at the burner front for correct atomisation. No. 6 oil essentially is a refinery by-product.

Due to the demand of low sulphur content and low fuel bound nitrogen fuel oil to meet the stringent limits dictated by the environmental protection agency regulations, light distillates with characteristics as having low sulphur content and low fuel bound nitrogen are blended with high sulphur and high fuel bound nitrogen residue to produce an improved fuel. However, blending light distillate oils with heavy #6 influence other properties of oil. For example, API gravity, heating value per gallon of oil; viscosity, and the ash content as well as the emissions.”

Regards

Luis Marques

 

[jmw]

you could also visit

http://www.worldbunkering.com

and the article on ISO 8217 which illustartes the changing aspects of fuel oil quality.

JMW

http://www.ViscoAnalyser.com

 

[mbeychok]

21121956:

It is not quite clear what you mean by "combustion calculations and related subjects". If all you are trying to do is arrive at the amount of flue gas and its composition, then there really isn't too much difference between various fuels. For example:

(1) An 18 molecular weight natural gas combusted with 12% excess air yields 11,600 scf of wet flue gas per 10⁶ Btu of fuel, and that flue gas contains 8.8 vol% CO2, 2.0 vol% O2, and has a molecular weight of 27.7

(2) A 15.5 [°]API fuel oil with a carbon/hydrogen ratio of 8.1 by weight combusted with 15% excess air yields 11,930 scf of wet flue gas per 10⁶ Btu of fuel, and that flue gas contains 12.4 vol% CO2, 2.6 vol% O2, and has a molecular weight of 29.0

(3) A coal (containing 47.9 wt % carbon, 3.4 wt% hydrogen, 10.8 wt% oxygen, 6.0 weight % ash, and 30.4 wt% moisture) combusted with 20% excess air yields 13,985 scf of wet flue gas per 10⁶ Btu of fuel, and that flue gas contains 13.5 vol% CO2, 3.3 vol% O2, and has a molecular weight of 29.0

The scf in the above data means standard cubic feet measured at 60 [°]F and 1 atmosphere.

As you can see, the amount of flue gas does not vary drastically whether using gas, fuel oil or coal. Hence, you can assume there will be even less variation from one heavy fuel oil to another.

For more details of the above examples, visit:

http://www.air-dispersion.com/formulas/html#combustion

Milton Beychok
(Contact me at www.air-dispersion.com)
.

 

[25362]

Mbeychok is right.

The flue gases resulting from the combustion of petroleum-based fuels, have about the same enthalpy (kcal/kg) at equal temperatures, with little error.

See the following table copied from the literature:

^oC 300 400 500 1000

Butane, no xs air 79.6 108 136.6 291
Butane, 28% xs air 79 106.1 134.5 286
Mex. oil, no xs air 78.8 106 134.2 288
Mex. oil, 28.5% xs air 77.6 105.5 132.5 284
asphalt, no xs air 78 105 133.2 284
asphalt, 28.5% xs air 77.2 104 131.6 280

Beside xs air, the other factor that may somewhat affect the enthalpy values is the water content of the gases (compare butane with asphalt).