Mercury in crude 1

[dhdsvr]

1. What is the limit normally allowed for mercury in crude ?
2. What are the harmful effects ? (Pl give references)
3. Is there any treatment to remove mercury ?
4. Apart from LPG and naphtha will mercury be found in any other products after refining ?
5. What are the mercury limits being followed by different refiners ?
6. What are the crudes ( regions) that have high mercury content ?

 

[epoisses]

Re 3, you could consider CMG273 or CMG275 guard beds from Axens.

 

[25362]

Have a look at:

thread481-83955

http://www.chem.unep.ch/mercury/2001-ngo-sub/sub15ngo.htm

http://www.uop.com/objects/87MercuryRemoval.pdf

 

[PAN]

dhdsvr,
I don't have the reference of harmful effect in the refinery. However, during turnaround maintenance period the elemental mercury could be found in the equipment. You should have procedure to detect the mercury vapor before apply the confined space permit.

 

[drqkag]

The limit of mercury in crude oil acceptable to refineries depends on where the refinery is and what it makes. Generally speaking, refineries that make motor fuels are less sensitive to mercury than those that make naphtha for petrochem. If the refinery is in a country that regulates stringently mercury in wastewater, the acceptable limit may be determined by this aspect. Mercury in crude at 50 ppb is problematic to all refineries. Mercury at 5 or less is not considered especially problematic to refineries that make mostly gasoline.

It is certainly true that there is more than one mercury species in crude. The elemental and dialkyl forms are volatile and end up in LPG and naphrtha. There are non-volatile forms (asphaltene and chalcogenides) that follow residua.

Chech out publications on hgtech.com for more details.

 

[PAN]

drqkag,
I'm interested in yout comment that 50 ppb is problematic to all refineries. Could you please let me know the reference paper?

 

[drqkag]

PAN - reference on mercury limit.

Wilhelm, S. M., “An Estimate Mercury Emissions to the Atmosphere from Petroleum”, Environ. Sci. Tech., Vol. 35, 24:4704 (2001). There is no limit specified in this reference but the rationale for one is explained.

The 50 ppb limit is arbitrary based on my personal experience. In this region of concentration refineries see a variety of so called "acute problems". Product quality suffers due to high mercury in LPG and naphtha. Wastewater mercury becomes elevated and wastestreams develop concentrations that make disposal difficult. Mercury accumulation in steel surfaces presents HSE issues.

Certainly, a tanker cargo at 50 ppb can be blended back if the mercury assay is known in advance but running crude at 50 ppb on average would require concerted efforts to mitigate effects. For some refineries that are strictly regulated, the limit might be 20 or 10 ppb. In some places in the US, wastewater regs are at ppt levels and mercury in crude limits may be set even lower.

 

[PAN]

drqkaq,
Thanks for the comment. I used to discuss with Dr. Wilhelm. However, there is no conclusion about mercury limit in refineries.

epoisses,
CMG 273 may be a choice in mercury adsorber. However, please ensure that you have no H2S present in the stream for this adsorber.

 

[EdStainless]

Just a thought,
Most of the comments have centered on the evironmental and regulatory side of things.
There are also operational effects. I have conducted failure analysis on valves that failued due to LME from Hg exposure.
As the crude goes through temperature and pressure changes the re is a chance to seperate out Hg in some process equipment. You need to have an idea of where this amy be and how to handle it.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm