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Old 11-01-2011, 07:38 PM   #21
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RE: 120 lehman oil usage

Total Loss Lubrication Systems:

*

http://www.skf.com/portal/skf_lub/ho...ntentId=868484

http://www.rotaryeng.net/Wankel-CC-paper.pdf* (page 10)

http://www.dropsa.com/flex/cm/pages/...N/IDPagina/839

http://www.gasturbine.pwp.blueyonder.co.uk/NPT301.htm

http://www.century-of-flight.net/new...ines_frame.htm

http://www.scribd.com/doc/48258552/e...The-Jet-Engine* (page 76)
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Old 11-01-2011, 07:49 PM   #22
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RE: 120 lehman oil usage

I would have never guessed there was actually something called a Total Loss Lubrication system. The "explantion" given to me at Land Rover was in jest and based on the propensity for older engines, particuarly older generation British engines, to leak oil like sieves as they aged. As the oil leaks out onto your driveway you have to keep pouring new oil in.

I guess that "explanation" was based on somehing real, albeit not a system designed to take advantage of the oil leaks an old engine devlops.
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Old 11-02-2011, 01:07 AM   #23
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RE: 120 lehman oil usage

Guys the closest thing to a total loss LO system that is still around is the cylinder lubrication of a large cross head diesel engine such as those manufactured by Man B&W
and Sulzer (now owned by Wartsila).
The cylinder lubricant (different oil to the crankcase oil) is injected into the walls of the cylinder liner to libricate the piston.
This oil is used and burnt completely and an engine such as a Sulzer 7RND 90M (7 cylinder 27000 HP 900 mm (36")bore) used approx 200 lts per day. I am a bit rusty on the figures.
There are still thousands of these engines at sea.
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Old 11-02-2011, 04:58 AM   #24
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RE: 120 lehman oil usage

Quote:
Tidahapah wrote:This oil is used and burnt completely
It's been a while since you mucked out a scavenge space, eh Benn?
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Old 11-02-2011, 10:35 AM   #25
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RE: 120 lehman oil usage

Suzuki had oil injection into the ring lands at BDC on some of their 2 strokes. But of course all 2 strokes are "total loss" except DD.*

*
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Old 11-02-2011, 01:44 PM   #26
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RE: 120 lehman oil usage

And the engines Benn was talking about, those are 2-strokes. They are the most powerful engines on the planet and they are the most efficent diesels ever built.

Here are some pictures of some work being done on an 11 cylinder 66,400 hp version that weighs around 1700 tons and drives a 66000 ton containership at 25 knots.

The first picture shows hydraulic "jacks" in place on the bolts that hold the lower end of the connecting rod to its lower bearing half.

The next one shows half a main bearing shell.

The last one shows the cap that holds that bearing.
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Old 11-02-2011, 04:22 PM   #27
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RE: 120 lehman oil usage

Quote:
RickB wrote:
And the engines Benn was talking about, those are 2-strokes. They are the most powerful engines on the planet and they are the most efficent diesels ever built.

Here are some pictures of some work being done on an 11 cylinder 66,400 hp version that weighs around 1700 tons and drives a 66000 ton containership at 25 knots.

The first picture shows hydraulic "jacks" in place on the bolts that hold the lower end of the connecting rod to its lower bearing half.

The next one shows half a main bearing shell.

The last one shows the cap that holds that bearing.
Would just about fit in my machinery space (if I took out the machiney).
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Old 11-02-2011, 05:53 PM   #28
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RE: 120 lehman oil usage

Thanks Rick,
Being on Rig Tenders these days didn't have any photos of the good old days at hand. (a lot of CAT 35Bs etc plus Wartsilas on the bigger units)
Still remember scavenge space and clean outs but for me that was a long time ago, I didn't do piston /ring inspections until the boys had completed the cleaning.
Guys FYI one could crawl down the exhaust trunk of these engines and carry out a piston inspection and partial ring inspection by turning the engine.
The good old days .
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Old 11-03-2011, 06:56 AM   #29
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RE: 120 lehman oil usage

Yeah, "good old days" look a lot better from a distance.

It has been a while since I was involved in a piston pull or tensioning through bolts and, you know, I don't really miss it. Glad I had the experience but not too keen to do it again.

My "chief mate" just departed Guam headed for China on a boxboat so I am sure she will soon be telling me about everything I am missing.
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Old 11-03-2011, 10:34 AM   #30
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RE: 120 lehman oil usage

Well that's something to crow about.

"2 stroke engines are the most efficient engines on the planet"

I do'nt think my Evinrude e-tech burns less than the 4 strokes but it's very close. And the lube oil is always fresh and clean. What kind of scavenging systems are employed on those monster 2 strokes Rick?
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Old 11-03-2011, 12:21 PM   #31
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RE: 120 lehman oil usage

Quote:
nomadwilly wrote:
"2 stroke engines are the most efficient engines on the planet"

What kind of scavenging systems are employed on those monster 2 strokes Rick?
*THOSE 2-strokes are the most efficient engines on the planet, not 2-strokes in general.

They are valve uniflow. The turbocharger discharges into a large (walk-in on larger engines) manifold that opens into the scavenge space.

A single hydraulically operated exhaust valve at the top of the cylinder opens as the piston nears the bottom of the stroke.* Circumferential slots near the bottom of the cylinder allow air to enter when the piston clears them on the way down after the exhaust valve opens. Fresh air washes the exhaust gases out of the cylinder, the valve closes, the piston moves up and compresses the charge after it passes and closes off the ports.

Benn mentioned the cylinder oil. It is delivered by a separate pump to ports drilled through the liner that feed grooves to distribute a special high base number cylinder oil to lubricate the piston. There just isn't any other way to lube the piston since it is not in common with the crankcase, plus a few other major reasons that would take up too much space here to talk about.

Since not all the cylinder oil burns away, some poor junior engineer has to crawl in the scavenge space to muck out the sludge that collects around the packing gland where the piston rod enters the space.

The line drawing shows the gas flow through the engine. The stuff between the turbo and the scavenge space is a charge air cooler and mist eliminator then the scavenge air manifold itself.

The first picture shows a view inside the "intake manifold" looking toward the far end where there is another access door. The boxy looking bit on the lower left is a set of check valves that allow using an electric blower to supply air when starting. The openings on the right are where air goes into the scavenge space. If I had turned the camera a bit more to the right you would see the cylinder and the slots where Benn talked about inspecting the rings.

The next picture shows the top of the engine with labels.

Next is an exhaust valve being removed for service and inspection. Note the valve itself is hanging open. Air pressure keeps it closed rather than a spring. That air is called "spring air" of course.

Next is the valve after being removed from its house. The angled vanes are there to use energy in the exhaust gas to rotate the valve so it self cleans carbon and crud from seating surfaces. The smiling gentleman is a warranty tech from Denmark who was there to inspect the parts as much of this was a warranty job rather than unplanned maintenance.
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Old 11-03-2011, 09:27 PM   #32
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RE: 120 lehman oil usage

Really good stuff Rick. Thanks a lot for sharing w us. Basically it looks like a DD w some rather large mechanical differences. Why the exhaust gas receiver? Does it reduce the force of the pulses? I'll bet the cooler really helps w efficiency. How many cylinders? How is it for noise?
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Old 11-04-2011, 05:23 AM   #33
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RE: 120 lehman oil usage

Except it is a crosshead engine like a reciprocating steam engine. The piston and piston rod are solidly connected and the piston rod only moves vertically. There is a crosshead between the connecting rod and the piston rod and that is where the wristpin is located and there are vertical bearings to take the side thrust.

Slow speed 2-stroke engines gain quite a bit of efficiency (>5 percent) through "constant pressure" turbocharging rather than the pulse type on smaller engines. The exhaust receiver converts the velocity of the initial exhaust pulse to pressure and supplys the turbine with a constant flow at a constant pressure.An interesting bit of trivia ... the turbochargers on these engines turn slowly compared to those on a trawler sized engine, around 10,000 rpm rather than 150,000 or so but each turbine blade "feels" a force of around 100 tons trying to pull it off the disk.

The engine in the pictures is an 11 cylinder version. They are noisy but not as miserable as a smaller engine. At low speeds you can hear the rings singing as they move up and down in the cylinder an dyou can hear and feel each combustion event. The turbos will kill you though, they are very large, turn very fast and move a huge volume of air. Even though they are pretty much sound-shielded, just the air flow noise is gruesome. A lot of the noise in the engine room comes from all the auxilliary machinery, pumps, compressors, centrifuges, fans that are needed to support the main engine.
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Old 11-04-2011, 06:30 AM   #34
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RE: 120 lehman oil usage

Rick:

Your whole explanation of this topic is extremely well written! Even I can understand it!
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Old 11-04-2011, 06:58 AM   #35
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RE: 120 lehman oil usage

Thanks Seahorse, I am glad you liked it.

It's not all that difficult to write about something you know and enjoy.
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Old 11-04-2011, 07:45 AM   #36
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RE: 120 lehman oil usage

Quote:
RickB wrote:
*It's not all that difficult to write about something you know and enjoy.
Interesting discussion.

So what size / types of ships are these 2 cycle engines used on? *Why would they use these rather than a 4 stroke, what are the advantages? Are they burning diesel or bunker fuel?

Looking at the size of the valve and pistion, they are huge and for me, having never owned or worked on a 2 cycle engine larger than an outboard, very complicated.

Sorry too many questions

LB
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Old 11-04-2011, 08:54 AM   #37
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RE: 120 lehman oil usage

"... what size / types of ships ...?"

Generally the larger ships that operate on long haul voyages where fuel economy is very important.

"Why ...?"

These are slow speed engines, they turn at around 100 rpm. They are directly coupled to the propeller shaft so no reduction or reversing gear is required. They are perfectly matched for the ship speed, propeller size, power requirements, and operating envelope.

They normally burn what is called an "intermediate fuel oil" or IFO. There are a couple of varieties of IFO and they are classed by their viscosity in centistokes. The most common fuels are IFO 180 and IFO 380. These are a blend of "bunker oil" and distillate (diesel fuel) to obtain the required viscosity at a specified temperature.

At "normal" temperature these fuels are very similar to SAE 20 motor oil. They are not as miserable as folklore has it. Both fuels have to be heated before they can be injected since the fuel injector doesn't really know what it is being served, it expects a certain viscosity and doesn't work well if it doesn't get it. At around 125 C or about 260 F, IFO is just like diesel and the injector is happy.

A good illustration of this is that a diesel injection shop will use a "diesel test fluid" instead of diesel fuel for safety reasons. This stuff has the same flow and viscosity as diesel fuel. The same test fluid is used to test your injectors and those on the largest diesel engine made.

Cylinder sizes vary quite a bit. The pictures I posted were taken on an engine with 900 mm pistons or a hair under 36 inches. The stroke on that engine is over 8 feet though, and that is one of the reasons it is so efficient. To get enough fuel into the combustion chamber in the time available requires multiple fuel injectors, some use 2 and others use 3.
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Old 11-04-2011, 09:53 AM   #38
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RE: 120 lehman oil usage

RickB

On land based diesels the use of "bunker" fuel has been purportedly stopped due to emissions legislation. At least 25 years ago a generator station I am familiar with suffered this fate. I've read the same is affecting*ships in some harbors such that "bunker" fuels are no longer allowed. BS, facts rumors** ---?
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Old 11-04-2011, 10:31 AM   #39
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RE: 120 lehman oil usage

Rick,

I see another way those engines are very efficient. Long stroke engines have less cylinder and combustion chamber area than shorter strokes and these engines you present have extremely long strokes compared to the bore size so minimal heat loss through cylinder walls and combustion chamber is achieved. I suspect that bore stroke relationships of this magnitude probably can't be achieved w the normal piston, crank and rod arrangement. Just say'in.
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Old 11-04-2011, 10:44 AM   #40
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RE: 120 lehman oil usage

Quote:
sunchaser wrote:I've read the same is affecting*ships in some harbors such that "bunker" fuels are no longer allowed. BS, facts rumors** ---?
Marine fuels fall under a different regulatory regime than terrestrial fuels. The sulfur limits vary all over the board from a maximum of 4.5 percent down to 0.1 percent. The variation is related to in-port, at-sea, in special rules zones or Environmental Control Areas, within 24 miles of California and a few other circumstances. The trend is to ultra low sulfur or exhaust treatment that provides the same reduction in emissions.

When a sea going ship burning a heavy fuel oil comes within 24 miles of the California coast it must changeover to burning low sulfur fuel. In most cases this means changing to diesel fuel. Most ships do this anyway because you can't shut down the engine with heavy oil in the system without risking not being able to start again and maneuvering with heavy oil can be really risky. The problem is that changing over is not without its own risks and loss of power during the changeover is not uncommon.

Several US west coast ports and a few more in Europe have installed shore power facilities so that ships can "cold iron" and shut down their generators to reduce exhaust emissions. This is going to be how it is done in all but the smallest ports before long since fuel costs are rising so fast and emissions are such a big problem.

When I was working on steamships we had to changeover to low sulfur bunkers when we entered California waters. This was a very expensive proposition since we had to keep a separate tank for the stuff and there were not many places to load low sulfure heavy oil ... and this was the heavy heavy oil.

I am not well informed about the power industry but oil burning plants are in the tiny minority these days. The last figure I have for oil foired plants is about 1 percent of total power generation in the US. Coal and natural gas are around 75 percent.

The move to use LNG for ship power is growing in some segments. LNG tankers have used boil off gas for fuel for ages and now LNG powered offshore supply boats are using it for power. There is even talk of building coal fired steamships again since techniques have been developed to clean up the stack gas and coal is relatively common and cheap.
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