Low Sulphur Diesel

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JollyJack
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Low Sulphur Diesel

Postby JollyJack » Tue Feb 24, 2015 11:40 am

I wonder is anyone has come across, or heard of, any loss of power when operating the main engine on low sulphur fuel?
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Big Pete
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Re: Low Sulphur Diesel

Postby Big Pete » Wed Feb 25, 2015 12:24 am

I have heard that it has less lubricity than normal fuel, that could cause faster wear rates in the fuel pumps and injectors, leading to loss of power. Bio Fuel is also Hygroscopic so emulsification with water can also be a problem, increasing wear rates and reducing calorific value. I don't think the Cetane Number is any different.

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Re: Low Sulphur Diesel

Postby TrustMeI'mEngineer » Thu Feb 26, 2015 11:33 pm

I agree with Pete, sulphur has good lubricating attributes. Usage of low sulphur fuel oil eliminates air pollution but creates problems regarding lubrication in engines.

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Re: Low Sulphur Diesel

Postby Big Pete » Fri Feb 27, 2015 12:41 am

Thinking about this again, if you are changing from High Sulphur HFO to Low Sulphur MGO, although the Calorific values will be very close, the density will be less. The fuel limiters, mechanical stops on the fuel rack, will be set up to give full power on HFO. The same mass of MGO should give the same power as any given mass of HFO, but will require a larger volume, the fuel stops limit the volume of fuel not the mass. If they are adjusted to give full power on MGO they will enable the engine to be overloaded on HFO. It would be a pain changing the limits every time you change over fuel so I guess that is just something you have to live with along with the increased loss of power due to internal leakage in the fuel pumps, with the lower viscosity fuel.
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Re: Low Sulphur Diesel

Postby JollyJack » Fri Feb 27, 2015 9:00 am

The lubricity is not from the sulphur. The reason low sulphur fuel has less lubricity is that the cheapest process to remove the sulphur uses hydrogen, which is highly reactive and reduces the lubricity of the fuel itself.

That makes sense Pete, the limiters regulate fuel flow by volume, not mass, so yes, it would take a higher volume of LSMGO than HFO for the same calorific total. The engine would lose power. Thanks :)
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Re: Low Sulphur Diesel

Postby JK » Fri Feb 27, 2015 12:59 pm

I was on a ship in the early 90's that lost the majority of fuel pumps on two Stork Werkspoor engines due to low lubricity FO. We were also transferring fuel and had the FO transfers pump seize. We had taken fuel by truck, in PEI, if I remember correctly. I think we couldn't get marine fuel oil. It's been awhile and I can't remember much more.i wonder if the log books are around , it would be interesting to see what the readings were.

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Re: Low Sulphur Diesel

Postby JollyJack » Fri Feb 27, 2015 7:30 pm

The sulphur in road diesel, ie the stuff you get at gas stations to power highway trucks, is 0.05% sulphur at the most. The sulphur content of marine fuels inside the ECA shouild be 0.1% or less. The viscosity of that stuff would be 1 to 1.4 Cts, marine engine manufacturers recommend a mimimum of 2 Cts, so I'm not really surprised at your fuel pump problems. I bet all the Buna N seals let go, too!
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Re: Low Sulphur Diesel

Postby Merlyn » Sat Feb 28, 2015 12:31 am

Remember when low sulphur diesel came out in UK and we had a few problems with engines running on 28 sec gas oil, not HFO. Old lifeboats with Perkins 6.354's had DPA pumps ( rotary) which of course had no engine oil supply like the inline pumps and relied solely on the Fueloil as a lubricant for the pumps head and rotor/O rings and bearing etc. Several throttle spindle O rings leaked and we had a genset using white diesel (Came from France) not UK whose injector pump had sized. There was a rumour that when called out to such a seizure that like the old boiler tube repairs that a bucket of ice would do the trick. Although in this case you did not put your tools in the bucket you poured the contents over the injection pump to free it off but this I never had to do.
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Re: Low Sulphur Diesel

Postby JollyJack » Sat Feb 28, 2015 9:10 pm

Rotary pumps have been particularly vulnerable, with lower lubricity of the fuel and Buna N seals in the pump, it seems to be a coupling designed in in marinje hell. Ice on the pump woukd increase viscosity, and so increase lubication. DNV saw this coming a few years ago and recommended a cooler for the LSMGO to increase the viscosity. 1.4 Cts is too low, engine manucacturers recommend a mimimum of 2 Cts.

Wartsila will accept 2 Cts, but that's with 2% sulphur fuel, which can't be used inside the ECA.
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Re: Low Sulphur Diesel

Postby D Winsor » Sun Mar 01, 2015 6:28 pm

On the ship I'm on now we routinely switch between 1% Sulfur IFO and LSMDO on medium speed engines with Bosh fuel pumps without any major issues. The LSMDO has a viscosity of 3- 4 Cts and is not as dry as LSMGO. The only engines I have ever seen that runs well on LSMGO are high speed engines that have a high volume fuel recirculation systems, such as Caterpillar, Detroit, Cummins and some Volvo engines. The high volumes of fuel being circulated through the pumps, between 4 -5 times engine consumption or higher, helps keep the fuel temperature as low as possible preventing a further loss of viscosity due to increased temperature and reducing the risk of pump or injector seizure.
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Re: Low Sulphur Diesel

Postby JollyJack » Mon Mar 02, 2015 8:18 pm

The engines you mention, Cat, Cummins, etc, are primarly vehicle engines and fuel sold for these have less than 0.05% sulphur to comply with US EPA Regulations. Incidentally, I used to think Cats were the biggest pieces of shit ever designed to sell spare parts.....then I worked on Cummins.
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Re: Low Sulphur Diesel

Postby Max Oiltemp » Mon Mar 09, 2015 4:21 pm

FWIW, I have spent the last few years working for a 'green' seismic outfit - SCR exhaust treatment, trick glycerine-based stern tube lubricants, biodegradeable hydraulic oil for the deck machinery, etc., and low-sulphur diesel (one of their major marketing strategies was the vessels' low carbon footprints). If it was available, we burned it - if not, normal MGO went into the engines (Wartsila 9L20 medium speed). I can honestly say that during the time I worked there, we must have changed back and forth maybe a dozen times - Trinidad, Suriname and West Africa on MGO and the North Sea/Bering Sea and off the coast of Portugal on low sulphur and we didn't have a single instance of power loss or pump failure. AFAIK, none of the other seven ships in the fleet have either. The one time I did see it was when working in the Arctic in the early eighties - we burned Arctic Diesel, also known as P-50 - and had to add a few gallons of lube oil to the storage tanks every time we bunkered (Werkspoor V-16 two-strokes). Perhaps the more modern marine engines have been designed with the previously mentioned factors in mind? The 9L20s, for instance, do have a F/O cooler...

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Re: Low Sulphur Diesel

Postby JollyJack » Mon Mar 09, 2015 7:14 pm

You'd need the arctic diesel up north, the cloud point is much lower, as is the sulphur content. The hydrogen treatment which removes the sulphur would also diminish the lubricity of the diesel. DNV and ABS provide line sketches of a fuel cooler installation to assist with keeping the viscosity index above 2 cTs.
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