Latent Heat of Vaporization and Molecular Mass of Vapor for Asphalt/Bitumen and Used Motor Oil

jimmyhutmacher · Jan 18, 2022

I'm looking at designing emergency venting for two different tanks, one for asphalt/bitumen storage and one for used motor oil storage. In order to design the venting I need the Latent Heat of Vaporization and Molecular Mass of Vapor for both liquids.

I scoured the internet and haven't come up with anything definitive. I did come across the Vetere Model for the Latent Heat of Vaporization of Pure Hydrocarbons = 4.1868*T *(9.08+4.36*log(T)+0.0068*T/M+(0.0009*T^2)/M) T = Boiling Point in Kelvin M = Molecular Mass of Liquid Not sure if this is accurate since asphalt and used motor oil are composed of innumerous types of hydrocarbons with great variation in boiling points and molecular weights.

I don't need exact numbers, just need to be reasonably accurate and conservative. Is there some kind of database or equation?

P.S., I have no access to any software that would do this analysis.

Any help would be greatly appreciated. thank you

georgeverghese · Jan 18, 2022

Bitumen almost always has a low bp hydrocarbon diluent in it - some light naphtha or natural gas condensate - NGL. So major component of this condensate may be approximated to be pentane or hexane. The lightest boiling component in NGL maybe isobutane but it isnt the major component. See which of these has the lowest latent heat.

Suspect re processed used motor oil may also contain small amounts of low boiling extraction solvent used in the reprocessing operation.

blacksmith37 · Jan 21, 2022

Asphalt is a mixture of asphaltenes , resins , and oils ; It will depend on what was used to make the mix. Traditional motor oils themselves have very low vapor pressure ; likely additives and contamination will produce any significant vapor pressure.

jimmyhutmacher · Jan 25, 2022

blacksmith37,

"likely additives and contamination will produce any significant vapor pressure." *will or won't?

After a fruitless search for the Latent Heat of Vaporization and Molecular Mass of Vapor, I ended up just using the "cookie cutter" API 2000 emergency venting tables for hexane. I believe these will be conservative and economical for the asphalt/bitumen and motor oil storage tanks. Let me know what you think.

georgeverghese · Jan 25, 2022

Nonane or decane or ethyl cyclohexane or any of the isomers of trimethyl benzene would be a good start for the major light component in the cutter oil boil off from a hot bitumen storage tank.

With low pressure tanks with design pressure <15psig, continuous boiloff during normal operation with hot bitumen storage (say at 150-180degC) should be expected. This would preferably be routed to a thermal oxidiser, since aromatics content in this cutter oil diluent (which may be some light diesel or kerosene like fraction) boiloff is too high to allow safe venting to atm from a HSE perspective in most developed countries.

Else get the plant owner to declare the composition of light components ( and any aromatics with HSE concerns), and vapor pressures at max operating storage temp for the range of cutter oils to be used in the grades of bitumen to be stored in these tanks.

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Latent Heat of Vaporization and Molecular Mass of Vapor for Asphalt/Bitumen and Used Motor Oil

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