Lubrication free condensing?

[fredrosse]

Ran across some EC literature, while voltages were not given, the power required was mentioned at "4 kW-hr/1000 gal".

A typical group 27 automotive battery can store on the order of 1 kilowatt-hour of electric energy, so good for about 250 gallons water treatment.

Transforming these numbers into small steam launch practice, say a steam plant using 100 pounds per hour steam, corresponding to an engine of perhaps a couple horsepower. An automotive battery here would last for about 20 hours running, using the equivalent of 50 watts power continuously while treating 100 PPH feedwater flow.

Not knowing anything about chemistry I have no idea if these numbers change much based on the amount of oil being removed from the water, etc. Of course, after EC treatment the sludge skimming we use in hotwells must also be applied, but the EC treatment evidently makes normally "unbreakable" emulsions into easily separated mixtures.

[barts]

I'm wondering if these power levels are actually what is required, or what that particular implementation used.... I've seen statements such as "0.4 kWh/m 3 for heavy loads, and 0.2 kWh/m3 for weakly loaded"; a cubic meter is order 300 gallons, so this is somewhat more efficient, but higher numbers are also out there. I wonder if the power requirements are different for just getting the the oil to separate; we're still using mechanical filtration as opposed to a lot of these systems which actually get the oil to form a sludge.

This seems a useful and relatively simple experiment for this spring; I already have battery power for lights and a fuel pump, and want to use a bit of lubrication this year.

- Bart

[Lopez Mike]

I've just re-read all the posts on this and I don't see what problem is being addressed. Like something has happened in the last hundred years?

I don't see why a non-superheat engine needs internal lubrication? Just one more danged thing to deal with instead of enjoying boating.

[DetroiTug]

Ok I'll bite

For sake of discussion and what I've observed:

I've heard that several times, that with saturated steam, no oil is needed - the water lubricates the engine. Also that Locomotives didn't use hydrostatic oilers. I researched this a while back and every mainline Locomotive I could find that explained it's operation and various components had a displacement lubrication or injection lubrication of some sort for the steam line. If I remember correctly, hydrostatic lubrication was invented for the railroad and it wasn't invented by the guy everyone here in the states says it was. It was invented by John Ramsbottom from the UK. Then I look around and see all these surviving hydrostatic lubricators which is inconsistent with something that wasn't used much. I have 5 or 6 of them.

The guy from Green velvet was very adamant about using lubrication and use the PBJ as it can be separated in the hot well. The Sapon oils with tallow cannot be used in a condensing system.

Then I talk to steamboaters that use no oil and learn some are on their second or third engine/rebuild in 10-20 years use. A steam engine has a pretty easy job to do, spared the impact of an internal explosion on each rotation, they should last much longer. I had a loose wrist pin I ran hard for two years, had it been an I/C it wouldn't have made it as far.

All the steam cars used a steam oiler of some type with and without superheat.

There just isn't a lot of evidence supporting widespread oil-less operation.

If it works, it works. Since I'm not condensing the boat or the car the routine is to use steam oil and so far so good on that. After many hours on the Tug, it will still run on 5 psi at steam temperature. I wouldn't run any metallic mechanism without some sort of lubrication. I think too about what would happen if I was to drain the oil out of my truck engine and fill it with water, it wouldn't run very long. I know it's two totally different engines, but in regard to the cylinder it still wouldn't last long. An I/C cylinder exposed to coolant perhaps in the case of busted head gasket is damaged in short order. The coolant dispersing the oil.

It's all a matter of opinion and whatever works.

-Ron

[fredrosse]

The lubricating properties of oil and water are very different, and water, while technically a lubricant, provides far far less lubrication capability than oil. Hence an engine running with wet steam as the only lubricant (in the cylinder and valve spaces) must have loads very much lower than is possible with an oil lubricated engine cylinder.

A trunk type piston, similar to automotive practice, would never survive with water lubrication, but a typical steam engine, with an external crosshead (oil lubricated) has no side loads on the piston, so water lubrication can work here. Provided the piston rings, or piston packing does not load upon the cylinder walls with too much force.

Unbalanced slide valves will generally groan and complain if there is no oil, but can be designed with low enough loading such that water lubrication is adequate. Piston valves without rings are balanced and are OK with water lubrication.

So in summary, water lubrication of the steam spaces on the engine is possible, and workable for some engines, with special features to allow this. Oil lubrication works far better, but has the condensate recovery problems because of oil contamination.

And you can indeed run condensing with compound oil lubrication of the cylinder, you just cannot re-use that condensate in the boiler!

[Lopez Mike]

I have no problem with lubricating a non-condensing power plant. I worked on a full sized locomotive for several years and nothing rusted anywhere on the beast due to the air compressor exhaust being full of oil drops. I didn't rust much either!

My engine fits Fred's criterium of being low stressed and piston valve. And I oil the hell out of the outside of the engine.

That said, my engine shows no sign of internal wear. Liberty ship engines ran such low oil rates that, if scaled down to our size, would be rather hard to measure the consumption.

As I said, I had this squeak that I attributed to rings, either on the piston and/or the valve. I plumbed on a small displacement lubricator just before where the steam line entered the valve chamber. Once in a while I thought I could tell a difference when I dumped some oil in there but it wasn't consistent. When I finally got down on my knees and poked around at the value packings the problem was apparent. Snugged up the valve rod packing just a bit and peace descended. At least for now.

Sure as hell it will start squeaking again and I'll have to breakfast on my words (gritting of teeth).

[DetroiTug]

Fred, good points.

I was talking to one of my older steam buddies who worked aboard a Navy steamer, and he said that no oil was used on the piston steam pumps or piston driven generator.

Those two devices were probably never throttled and ran wide open all the time when in use. When my lubricator runs out under way (I forget to fill it in the morning) the engine starts squeaking and if the throttle is opened fully, it gets quiet.

A steam car is throttled continually and all that I know of were fitted with oilers.

I think the deciding factor here in whether oil is needed in a saturated engine is/was determined by the amount of throttling.

The use of continuous oil is better overall, but not imperative depending on how the engine is operated.

This is probably something very obvious I'm just figuring out

-Ron

[Mike Rometer]

Perhap the quetion we should ask then is, what is water a lubricant for? I was taught that it was one lubricant for rubber. So, if metal rings squeal without oil, what aboiut uing 'O' rings. Agreed that wont help the valve faces but as Fred says that can be taken care of by light loadings. Which really only leaves the gland, which could also be changed to an 'O' ring. Surely someone has already tried this, what was the result?

[gondolier88]

O-rings have been used as piston rings, but just because they work does not mean they are a good solution- in order for the o-ring to be able to withstand reciprocating motion it must have no side play whatsoever or it malforms and runs the risk of tearing. So let's think what a correctly fitting o-ring can seal- depending on temperature it can seal pressures well in excess of our boiler pressures; so can we realistically assume that a film of water would remain between the o-ring and cylinder wall? I think not, rather a meniscus of water would be pushed either side of the o-ring seal.

In any application where ferrous metal is bearing against another ferrous metal then oil should be present. However, for engines running without lubrication I have heard good things about a plain iron piston with no rings working well- Tom with 'Talisker' designed his Cheape compound with this arrangement and has no appreciable wear or any pass-by so is probably the best way to go. I can't remember the clearance he runs with, but it would be paramount to have the piston in iron as it has to expand at the same rate as the cylinder to maintain the clearance.

Greg

[Lopez Mike]

As Greg says, an O-ring tends to rock back and forth in its groove and doesn't work well with high speed oscillations. Both O-rings and metallic rings work because the pressure is able to get in behind them and push out. The more pressure, the more outward sealing pressure.

I haven't been able to get an iron bore smooth enough to keep from chewing up O-rings. A metallic ring wears away the manufacturing imperfections almost immediately thus the nice shiny bores we see.

Any ring needs a small amount of side play for the working fluid, be it steam, hot gasses or liquid, to communicate to the back of the ring. The installed pressure is much less important than one might think. There is a type of ring (Dykes) that has an L section and has almost zero installed force against the bore. They work well and their light weight is important at very high I.C. engine accelerations. In I.C. and possibly uniflow steam engines the ring spends all of it's life against the bottom (low pressure side) of the groove.

This is why the wear pattern in I.C. engines is more at the top of the stroke than further down and hardly happens at all at the bottom. In fact, the wear pattern is a very nice measure of the pressure v.s. stroke history. High pressure near the beginning of the stroke and less as the pressure drops. In most engines the rings do not reach all the way to the end of the stroke and thus an unworn bit (ring ridge) remains. When replacing rings without boring the engine this ridge should be removed so that the new rings doesn't hit it and break the ring!

I know. Too much information. I'll go quietly.