Expected life expectancy from WMO?

[BioHazard]

It's been at least 15 years now since I've wanted a waste motor oil powered diesel generator. I'm trying to calculate the cost of a listeroid generator, vs the lifetime amount of electricity and heat it can generate from WMO, which I consider "free" fuel.

So let's say I get a good listeroid and go through the proper pre-start rebuild. How many hours could I reasonably expect from the engine burning the highest concentration of WMO I can get away with? Does 2000 hours seem reasonable? I would be happy to get 2000 hours before needing a new piston/rings/liner/bearings. Is that realistic? Certainly a lot less than the 10,000 to 100,000 claimed life expectancies. I would probably have some sort of natural gas dual fuel system going with the WMO, to help keep things as clean as possible. How often would it be necessary to take off the head and decoke the combustion chamber? What about fuel injectors, are they going to suffer premature failure as well?

Also, with a listeroid on WMO, would I be correct in expecting about 10kwh/gallon?  How many BTU of heat will that produce on 140,000BTU/gallon fuel? Roughly 2/3rds of that as heat?

[BioHazard]

Do these calculations sound right to anybody?
2000 hour life expectancy x 14kw (28/2 engine)  = 28,000kw at $0.11/each. Total $3,080 worth of electricity.
On top of that, 2/3 of the fuel converted to heat = 92,400 BTU/hour waste heat. If I was buying that as natural gas it would be 1,848 therms at a cost of $1.12+ each. ($2069 savings over 2000 hours buying the same amount of natural gas)

Total, if my listeroid could last 2,000 hours on free waste motor oil, I could generate a total of $5149 in heat and electricity, which I would otherwise have to pay cash for. I think I can get ahold of a listeroid for under half that.

Does my math make sense to anybody else?  Please, point out my flaws before I start spending money. 

[spencer1885]

From my experience with using WMO as fuel in a Lister I would keep the hours as low as possible.
As the engine wear is high and maintenance is also high I would and do use a WMO fuelled generator for power only.
The best thing is to set up a WMO heating system for your hot water and heating needs as this is the most economical way of producing heat and then it keeps the two systems separate.
No mods needed to the engine but you will have to thin the WMO will RUG by about 10 to 15%.
No wear to the fuel injection system in the 2000 hours plus I have been doing it and 2000 hours is possible with new rings, as the bottom end of the engine does not suffer at all.
When I pulled the head and block off at 1800 hours when the head gasket failed  apart from the rings and bore wear there was no more carbon than with a engine running on diesel,but Lister do recommend a decoke every 1000 hours.
The biggest problem is the rapid top end wear from burning WMO and also the coke that forms daily on the injector tip which all the things that have been mention before like injector heating,water injection,natural gas, acetone will not stop.

[BioHazard]

I would definately be ok with taking the head off every 500-1000 hours for a decoke, if I can get away with running free fuel. I'm thinking of Bob's 28/2 listeroid for this, so I should be able to get a lot of heat and power during a short run time producing ~14kw. (maybe 4 hours/day?) Some of that may go into a battery bank. Just thinking outloud here...

Stupid question: what is "RUG"?

[BioHazard]

Ah, ok "RUG" is regular unleaded gas. Right? Would mixing 10 or more percent of natural gas with the WMO take the place of "RUG", for cheaper, and cleaner performance?

[AdeV]

The RUG is added to reduce the viscosity of the fuel oil, not to enhance its burning characteristics. Indeed, put too much RUG in and you'll end up with detonation (pinking) and possibly other nasty effects.

I would have thought that if you centrifuged your WMO (I'm thinking of the Simple Centrifuges style unit, rather than a Dieselcraft type) clean, there's no reason why you shouldn't be able to aim for the 10K-100K hours mark (in total.... not between services). The biggest wear causing pollutant in WMO will be metallic particles, and the 'fuge should remove almost all of those.

If you reckon you can make about $5k of CHP out of a $3k listeroid, it's worth spending the extra $2k (say) on a centrifuge as you should at least double your engine's lifespan, maybe more. That's my thinking anyway...

[billswan]

Bio

you are doing the right thing ask a lot of questions first.

My 10/1 made it to 1775 before my camshaft broke. But my guess is it would have had a hard time making it to 2500 with the way the blow by was increasing.

If my plans hold I will pull the head and piston to day and will post pix. Will see if just a set of rings and a camshaft will bring it back to life.

Billswan

[mobile_bob]

it would seem to me that getting 10k hours before a rering would be common if the oil stock was well filtered
and dry, i would expect that the injection system would wear out far faster than the cylinder components
otherwise.

this is assuming good quality components and a clean/properly setup engine to start with.

as for blowby, i would accept a quite high amount, provide the engine still started well.
i would vent the fumes so that the engine could inhale them and eject them out the tailpipe
and not into the room.

having said that i probably would make up some sort of cooler separator so that the oil could be condensed out
for the most part, or at least monitored for excessive amounts, it is unlikely that the lister would have a runaway but
it would probably be prudent to protect against that happening.

its been my experience that many diesels have what one might call excessive blowby, and go on to run 100's of thousands of miles
without issues. early DT466 engine come to mind, many of which had serious blowby issues but ran fine for a very long time.

blowby burning veggie oils might be a whole dirreent animal however, because of the increased amount of veggie ending up in the crankcase.

bob g

[BioHazard]

The RUG is added to reduce the viscosity of the fuel oil, not to enhance its burning characteristics. Indeed, put too much RUG in and you'll end up with detonation (pinking) and possibly other nasty effects.

Could the RUG be completey substitued for pre-warming the WMO before burning?

Also, would burning some amount of natural gas in combination with WMO keep the enine cleaner/longer lasting than without? Something like an 80%WMO/20%NG mix maybe?

[AdeV]

The RUG is added to reduce the viscosity of the fuel oil, not to enhance its burning characteristics. Indeed, put too much RUG in and you'll end up with detonation (pinking) and possibly other nasty effects.

Could the RUG be completey substitued for pre-warming the WMO before burning?

Yep - if you can get the viscosity down to something similar to diesel, then you don't need any thinning additives.

Also, would burning some amount of natural gas in combination with WMO keep the enine cleaner/longer lasting than without? Something like an 80%WMO/20%NG mix maybe?

I don't know TBH. It would reduce the amount of WMO being burnt by the engine, so in theory it would be cleaner. Just more costly... I don't believe that adding NG will have a "cleaning" effect over & above the reduction of WMO deposits caused by the reduction of WMO used.

[spencer1885]

Hi Bob,
Before the LEF disappeared I posted my results from using WMO and it's long term use and the effects it had on an engine.
What I found was totally unexpected.
The results seem to indicate that when WMO is burnt it produces a white fine ash and this ash is abrasive and is the reason for the rapid ring and bore wear.
The white ash is produce by the burnt additives in oil which can not be filtered out,so if this indeed is the case then oils which do not have additives would be more suitable but I have not found such an oil apart from veg oil of coarse.

Spencer

[spencer1885]

The RUG is added to reduce the viscosity of the fuel oil, not to enhance its burning characteristics. Indeed, put too much RUG in and you'll end up with detonation (pinking) and possibly other nasty effects.

Could the RUG be completey substitued for pre-warming the WMO before burning?

Yep - if you can get the viscosity down to something similar to diesel, then you don't need any thinning additives.

Also, would burning some amount of natural gas in combination with WMO keep the enine cleaner/longer lasting than without? Something like an 80%WMO/20%NG mix maybe?

I don't know TBH. It would reduce the amount of WMO being burnt by the engine, so in theory it would be cleaner. Just more costly... I don't believe that adding NG will have a "cleaning" effect over & above the reduction of WMO deposits caused by the reduction of WMO used.

You can not use heat alone to reduce the viscosity of WMO like you can with WVO.
Engine oil is design to resist every thing you are asking it to do when trying to use it as a diesel fuel.
You  will never reduce it's viscosity enough for the the injector to spray properly, think about it if that was the case what good would it do the engine in the sump with the high temperatures and even higher pressures it would simperly brake down and not do it's job of protecting the moving parts.

[BioHazard]

I don't know TBH. It would reduce the amount of WMO being burnt by the engine, so in theory it would be cleaner. Just more costly... I don't believe that adding NG will have a "cleaning" effect over & above the reduction of WMO deposits caused by the reduction of WMO used.

One thing I wonder about is the production of water vapor in propane/natural gas combustion, which I understand helps by adding a bit of a steam cleaning effect. Any truth to this?

[BioHazard]

What I found was totally unexpected.
The results seem to indicate that when WMO is burnt it produces a white fine ash and this ash is abrasive and is the reason for the rapid ring and bore wear.
The white ash is produce by the burnt additives in oil which can not be filtered out,so if this indeed is the case then oils which do not have additives would be more suitable but I have not found such an oil apart from veg oil of coarse.

I wonder if this could be helped by cleaning the combustion chamber/piston more often, maybe every 250-500 hours? If I could find a source of used hydraulic fluid or automatic trans fluid, with less additives, would that help with engine wear?

[veggie]

Could the RUG be completey substitued for pre-warming the WMO before burning?

Not necessarily. This would be quite dependent on the source of the oil.
Remember that many automotive oils are multi-grade (eg: 10w-30) so adding heat would only reduce the oil viscosity to the range of a 10W oil. Still much thicker than diesel fuel.

Perhaps consider reducing the viscosity with kerosene due to it's auto-ignition properties and lack of pinging.

veggie