[Gasification] gas quality and engine lifespan?

[Kevin Chisholm]

Dear Ken

I have never run an engine on wood gas, so your comments certainly trump 
mine. However, there are some questions that puzzle me:

1: Propane and natural gas have no lubricating additives, yet these 
engines run well with no excessive wear problems.

2: Gasoline is a proven "lube oil solvent", yet these engines run well 
with no excessive wear problems.

3: Lubricating oil films are very thin, and would be at the temperature 
of the cylinder wall. It is hard to imagine them being able to reach 
combustion temperature.

4: I don't know anything about "vapor degreasing", but I am guessing it 
is the aerosol liquids in the saturated degreasing vapors that dissolve 
greases and oils and flush them away. Does anyone know of "dry" vapor 
degreasing gases will actually degrease? If not, then it would not be 
likely that "dry" CO and H2 would remove the lubricating film.

Is it possible that the excess wear that was observed was due to some 
factor mother than removal of lubricating film? For example, excessive 
carry-over of abrasive dusts and ash?

Best wishes,

Kevin

Ken Calvert wrote:
> Mark, Oops pushed the send button too quick.  You asked about  LPG and CNG.
> I would guess that the whole natural gas industry have worked that one out 
> long before they started to put up gas fuels for road use.   I would guess 
> that the whole expansion process sucks those gases into the cylinders just 
> as cool as a rapidly evaporating petrol vapour is and that the tendency 
> would be for the fuel to stay in the oil film and more fuel would end up in 
> the sump than oil is flashed off the cylinder walls for combustion. 
> However, thats only a guess. Over to someone else for the correct answer. 
> ATB. Ken C.
> 
> ----- Original Message ----- 
> From: "Mark Ludlow" <mark at ludlow.com>
> To: "'Discussion of biomass pyrolysis and gasification'" 
> <gasification at listserv.repp.org>
> Sent: Sunday, July 08, 2007 6:54 PM
> Subject: Re: [Gasification] gas quality and engine lifespan?
> 
> 
>> Great practical advice, Ken!
>>
>> Often times we overlook real-world considerations in our pursuit of 
>> "trick"
>> solutions that are really just armchair musings.
>>
>> Do you think the lubrication problems with clean wood gas are inherently
>> worse than, say, the use of propane or NG as a fuel? While my gut feeling 
>> is
>> that you are making a valid observation, I'm trying to relate it to some
>> physical characteristic of the gas that would actually result in less
>> effective lubricity (assuming that it's purged of abrasive ash residues).
>> Ever consider top-lubing with a co-current injection of funky oil, leaving
>> the good stuff to lube the bearing surfaces?
>>
>> Mark
>>
>> -----Original Message-----
>> From: gasification-bounces at listserv.repp.org
>> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of Ken Calvert
>> Sent: Saturday, July 07, 2007 10:18 PM
>> To: Discussion of biomass pyrolysis and gasification
>> Subject: Re: [Gasification] gas quality and engine lifespan?
>>
>> Javier, take it from an old timer,  the biggest wear factor with good 
>> clean
>> dry producer/wood gas is not the tars but the fact that it is hot and dry
>> and it will lick the oil off the cylinder walls.  The tars will impact and
>> get stuck in the inlet manifold and not much gets onto the cylinder walls.
>> To get any thing like a long life out of a PG motor you have to over
>> lubricate.   And you can't use the usual kinds of upper cylinder 
>> lubricants,
>>
>> because you haven't got any liquid fuel to dissolve them in.
>> The usual thing in WW2 was to leave out the oil seal rings on the bottom
>> flange of the pistons.  That means that you will use a lot more 
>> lubricating
>> oil, but your question is about longevity not about running costs or the
>> costs of  lubrication.
>>     For the purposes of  generation and experimentation,  by far the
>> easiest way is to choose a very common automotive engine that sells for
>> cheap at the local auto-wreckers  and keep yourself a supply of spares. 
>> If
>> they are already burning a bit of oil, then that is exactly what you want
>> because they will last longer than a new motor with tight rings.  Derate 
>> the
>>
>> load factor and they will laqst for years. The one thing that I can't 
>> answer
>>
>> is whether the polarised metal additives and super duper things that you 
>> can
>>
>> put in your lubricating oil nowdays will be of any help.  I would suspect
>> that the amount of oil you loose would make their constant replacement
>> rather expensive. I just hope that someone a mite younger than me can come
>> up with the latest and greatest to improve the situation.   Sincerely, 
>> Ken
>>
>> Calvert.
>>
>> ----- Original Message ----- 
>> From: "Javier Bonet" <jabonet at runbox.com>
>> To: <gasification at listserv.repp.org>
>> Sent: Sunday, July 08, 2007 6:30 AM
>> Subject: [Gasification] gas quality and engine lifespan?
>>
>>
>>> What is the life expectancy of a piston engine running on wood gas?
>>> is there any chloride and sulfur gases being generated that will reduce
>>> the life span of the engine, how do you cleans tars and avoid them from
>>> getting into the engine?
>>>
>>> Thanks, Javier.
>>>
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>>
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