Sludge in #2 Diesel Fuel

[Mkuchta]

We have an underground storage tank for #2 diesel fuel that is connected to an underground pipe with a fuel pump. Just before the fuel pump is a suction strainer that is examined every 18 months. A small amount (5oz.) of black, easily broken up material was found in the strainer and I was asked to ID it. The elemental composition (using edx) was primarily carbon with oxygen and sulfur and traces of phosphorus, calcium, chlorine, copper, iron, magnesium,and zinc. It's likely that the copper and zinc are from an indicator that was recently removed. FTIR analysis of the residue showed a spectra simlar to asphaltene or soot with NH4, aromatic and aliphatic CH,and SO4 peaks. There doesn't seem to be any water or ester peaks as in biodiesel.

Is this residue a normal function of aging diesel?
What is usually in sludge?
If this isn't normal what else could it be.

Thanks very much.

 

[JLSeagull]

Five ounces does not sound like much after 18 months.
I would expect some residual in diesel especially some biological stuff like fungus. The sludge composition is likely related to the type of crude oil. I would expect less residue with the ultra-low sulfur fuel oil grade than the grades that permit higher sulfur content.

 

[rmw]

Who knows what that truck that delivered the diesel was carrying on the load right before he/she loaded your diesel.

rmw

 

[BigInch]

Speaking of which, are you going to use that diesel some day. It doesn't last forever. Occasional filtering and possibly bio-treatment may be necessary. If you have no plans for use within the next year, perhaps you should think about selling it and filling with new.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Mkuchta]

Thanks everyone. The diesel fuel is topped off every so often and the tank is cleaned every 10 years. The fuel from the trucks is tested for viscosity, sediment, and particulate contamination before it is put in the tank. I was wondering if this residue is something that normally settles out of diesel fuel with aging.

 

[BigInch]

10 years is a very very very long time.
I think the general opinion on long term storage is for around two years, with filtering and biocides possibly needed, depending on actual conditions, with a max of perhaps 5 years, but not even Southwest Labs was really willing to say more than 2 was assured.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Mkuchta]

I agree that we are probably storing the fuel too long and not cleaning the tank out often enough.
I think the residue I found in the strainer is linked to degradation and aging in the fuel but I can't find information that will allow me to compare what I found in the residue to sludge that develops from aging. What exactly should I expect to find in sludge?

 

[BigInch]

Unfortunately could be a bit of anything and everything. That's why they call it sludge.

Dirt and Sand
Rust
Water
Algae
Bacteria
Metal flakes

Basically a combination of whatever has been in contact with the fluid PLUS a bit of whatever has been floating around in the air above the tank ever since it was produced.

We targeted a complete turnover of all stored fuels within a 2 year period. I'd not estimate more than a maximum of 5 years, monitoring and testing to confirm deterioration remains within an acceptable rate. Test at every 1 year maximum. Initial fuel composition can change from batch to batch and the conditions at the site can change over time too, so whatever storage period you've had in past years may change from batch to batch.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[rmw]

There have been quite a few threads on distillate fuels and the ravages of their storage. Do an advanced search on this site. I am too lazy to do it for you. A couple of words out of BigInch's post should score some hits; algae, bacteria, and add sludge to the list.

rmw

 

[chicopee]

Is the storage tank concrete?

 

[Mkuchta]

No, it's steel.