Cracked Fuel Oil Composition

[qazx]

Hi,
Does any one know a typical Cracked Fuel Oil Composition (CFO) from ethylene plants?

 

[UmeshMathur]

The fuel oil portion of ethylene cracker effluent is an incredibly complex, wide-boiling mixture. It is full of olefins, diolefins, triolefins, aromatics, polynuclear aromatics, etc. throughout the boiling range. I would guess there are probably millions of compounds in such a mixture, 99.99% of which can only be guessed at.

For design of the so-called gasoline fractionators (right after the furnace transfer line exchangers), highly simplified methods are used to characterize the heavy fuel oil portion. Typically, a true boiling point (TBP) distillation curve is assumed for the fuel oil components. This is based on the predicted yields from a pyrolysis program. The TBP curve extends all the way to 1500 degF. The shape of this curve is uncertain and much experience is required to obtain the proper shape.

Then, as in petroleum refining, pseudo-components are generated and used in column simulation. Unfortunately, the methods used in most process simulators to estimate the thermophysical properties of these pseudocomponents were originally developed for straight run petroleum fractions, not highly olefinic mixtures of the type you find here. So, the simulation results can be considerably in error, but it's hard to know in advance.

I hope this reply sheds some light on the incredible molecular complexity of the fuel oils from ethylene crackers.

 

[SmartEngineer]

Your question can not be answered correctly as it depends strongly on the Feedstocks either propane, butane, NGL, Naptha..etc or a mixture of these. The yield from furnace effluent is different from each type of feedstock. Another factor that makes the estimation of the CFO difficult is the furnace type and the licensor process.
In general, for a cracker with mixed Ethane & mixed Butane, a typical CFO can consist of C9-200C & Fuel oil and others as given by UmeshMathur.
The best way to get such data is the cracker licensor.

Cheers
SmartEngineer

 

[AndreChE]

Adding some more questions...to your question!

European Steam Crackers crack a wide variety of feedstocks along the year. During winter naphtha is the prefered feedstock and during summer they crack LPG, butane, propane and different mixes (E/P;E/B). Everything depends on the market, prices, plant constraints...

If you consider Middle East, it's very difficult to find a naphtha cracker, as you understand...

Pyrolysis Fueloil composition varies from plant to plant, cracking severity and operating conditions, summer time to winter time, if it is near a refinery or not...

 

[owg]

Check out Pyrolysis Fuel Oil on Google. You will see some Material Safety Data Sheets which characterize these fuels.

HAZOP at

http://www.curryhydrocarbons.ca

 

[Longinthetooth]

The only thing I can add to all the good information above is that the pyrolysis gasoline or pyrolysis fuel oil is often used as the dumping ground for any trash hydrocarbon floating around the plant, such as tars or grease, so you have to be careful where you sell/use it. Incidentaly, a lot of plants separate this stream(s) into Pyrolysis gasoline (C5-200C) and pyrolysis fuel oil (200C+) within the cracker itself. Be careful which one they are giving you.