Marine Diesels

[MolaKule]

Large Marine Diesels can weigh up to 2,000 tons and produce 50,000 or more horsepower. These engines run at 100 to 125 RPM.

These large, slow speed single acting 2-stroke crosshead type of engine is completely separate from the combustion zone of the engine, i.e. there is no direct communication between the combustion zone and the crankcase zone of this engine. This has led to the use of two different lubrication systems to lubricate a slow speed marine diesel engine.

Question: What is the TBN of the oil used to lubricate the pistons in the Combustion Zone of these large diesels.

 

[Pablo]

Starting? or Typical? or Ending/condemn?

 

[Pablo]

I mean these burn nearly crude oil, so I imagine you need a strong TBN - or is this a trick question?

 

[Mitch Alsup]

More importantly, these large engines can be 50% thermally efficient! 50% of the energy content of the fuel comes out the crankshaft! Compare this to the 25%-ish of typical passenger automobiles.

So, here we have a reciprocating engine where the crankcase is independent of the cylinder (in terms of lubrication). So the crankshaft stuff only has to worry about journal bearing loads and no acid buildups,...

While the piston oiling system has to worry about all of the acid byproducts of the buring process and the massive pressures at the ring/cylinder interfaces, and the gaps in the cylinder surface where the burned mixture is exhausted and fresh air is blown in at rather high pressures.

I might also note; that these engines use a piston with out a piston pin and a roller bearing cross slide to the actual connecting rod to get rid of the cylinder side loadings that more normal connecting rod designs have.

 

[TomJones76]

I'm betting 50! Like this oil:
http://www.exxonmobil.com/Canada-English/Marine/PDS/IOCAENMRNMOMobilgard_M50.asp

Of course, Exxonmobil also has one with 70 TBN:
http://www.exxonmobil.com/USA-English/Marine/PDS/GLXXENMRNEMMobilgard570.asp

 

[MolaKule]

quote:

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Starting? or Typical? or Ending/condemn?

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Starting TBN.

TomJones has some good examples.

The starting TBN is anywhere from 50 to 100 with the average being 70.

 

[Pablo]

Killer!

How often is this lube swapped?

AutoRx?

 

[Shannow]

Pablo,
I think (not entirely sure) that the piston lubricant ends up being consumed ultimately, while the crankcase lube is filtered and circulated.

 

[Rev440]

Wartsila-Sulzer 10 banger...Picture of crankcase, no oil.

http://www.bath.ac.uk/~ccsshb/12cyl/

I wonder how they pre-lube the thin bearings before crankshaft application.

 

[wavinwayne]

quote:

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Originally posted by Rev440:
Wartsila-Sulzer 10 banger...Picture of crankcase, no oil.

http://www.bath.ac.uk/~ccsshb/12cyl/

I wonder how they pre-lube the thin bearings before crankshaft application.

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I wonder if Amsoil makes anything for that?

 

[Shannow]

wayne,
I'm sure that they manufacture a lubricant that "meets or exceeds" the requirements for that rig.

 

[Pablo]

You might want to try the XL 5W-20. API has "approved" it........

 

[Shannow]

I wonder if CAFE have a rating ?

GF30...(gallons per mile)...maybe GF300

 

[mechtech]

I used to build Marine diesels [detroit diesel type] at Electo-Motive.

I'll bet no one in the plant, knew, either...

 

[frankiee]

Large crosshead engines usually 70 TBN

Trunk piston engines running on heavy fuel 30/40 TBN

Depending on sulfur content of the fuel
Crank case lube oil should have a high closed flashpoint above 200degree C to reduce the risk of crankcase explosion

 

[MF231S]

I have a hard time understanding how someone can own/operate a vessel that has 5 - 10,000 HP engines with a fuel tank in excess of 27,000 gal.? What would the cost of gas per gallon be if private Yatchs and Jets weren't allowed to navigate/fly? I will always be amazed by this nations corporation execs and their "golden umbrellas".

 

[Rev440]

quote:

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Originally posted by MF231S:
I have a hard time understanding how someone can own/operate a vessel that has 5 - 10,000 HP engines with a fuel tank in excess of 27,000 gal.? What would the cost of gas per gallon be if private Yatchs and Jets weren't allowed to navigate/fly? I will always be amazed by this nations corporation execs and their "golden umbrellas".

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Hmmph, speaking of golden umbrella...*Canada*
I have a friend who drives transport for Day/Ross a large Canadian logisitics company similar to U.S. Roadway...
...anyhoo, Day/Ross pays $.53 liter for diesel at PetroCanada fuel where consumer pays $.93 liter.

A large forest products company in our area has the same deal going with Husky Canada. Approx $.53/liter where consumer pay $.95
***Lots of siphoning going on with Buchanen***

The small guy is paying for everything....

 

[Steve S]

quote:

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Originally posted by MF231S:
I have a hard time understanding how someone can own/operate a vessel that has 5 - 10,000 HP engines with a fuel tank in excess of 27,000 gal.? What would the cost of gas per gallon be if private Yatchs and Jets weren't allowed to navigate/fly? I will always be amazed by this nations corporation execs and their "golden umbrellas".

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A good paying job!!!

 

[Ken2]

I've used SAE 60 TBN 70 cylinder oil. Any cylinder oil that is not burned is drained off into a tank. The installation intended for that drained oil to be filtered & refiltered in a diatomatious earth filter assembly, then added to the SAE 30 crankcase oil, but folks who did that ended up with the crankcase oil too high in TBN. We just mixed it with heavy oil and burned it in the boiler. (You can't run a heavy fuel engine without steam to heat the fuel...about 250°F before injection.)

The 12 cylinder engine consumbed about a ton of cylinder oil daily when running full power. The lubricators injected more oil into the ports in the cylinder walls at higher rpm. Max rpm was 95, and minimum was 35.

I think engine size currently goes up to about 104,000 hp on a straight 14 cylinder two-stroke diesel engine with a 980 mm bore. Some engines run as slowly as 76 rpm at full power. Arrangements are available from 4 to 14 in-line cylinders depending on the power needed.
http://www.manbw.com/engines/TwoStrokeLowSpeedPropEnginesProgram.asp

The fuel is high sulfur, up to 3.5%, and certainly not crude oil...crude oil has too much valuable stuff in it. Residual fuel oil is a better term--here's a typical spec sheet for IFO-500, 500 cSt @ 122°F.
http://www.usor.com/pdfs/specs/lpd/marine/IFO-500.pdf

The piston is bolted firm to a round piston rod. The piston rod slides through a seal. The crankcase is beneath this seal and does not get combustion gases. The crosshead does the job of a wrist pin...with a very large pin in babbit bearings. The SAE 30 crankcase oil is a life-time fill and continually centrifuged.

The lube oil, and maybe soon all lube oil, is in short supply due to a shortage of the chemicals to produce the additives.
http://www.imakenews.com/lng/e_article000454800.cfm?x=b5BNrBd,b19p9DCt


Ken

 

[MolaKule]

Thanks for the info Ken.

quote:

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Oronite to close its principal North American plant in Belle Chasse, La.

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Actually, it's supposed to be back on line about Sept. 19th.

And Infineum's supply of Marine lube adds seem to be ok.