[Gasification] ideal wood gas engine

GF gfwhell at aol.com
Thu Feb 24 18:51:33 CST 2011


Back when Teddy was at Odds with Arthur. Teddy imposed the three day week. I told my Boss that I could put ourselves back to a six day week with the aid of a Generator which we just "happened to have" for testing machines for export, This electric motor driven contraption was set up to produce  60 htz 3ph and needed to be "modified" to produce 50 htz. to run on NG. We needed about 20 HP  for our requirements, So I got hold of a scrap Morris Minor Engine, and swapped it out with the electric motor,which was belt coupled to the Generator.
Some changes in the taper lock pulleys and belts set the new contraption up for the lower frequency. Because the engine was "small" I decided to run it at a speed  fitting it's optimum out put curve. There were other problems such as the field voltage control of the generator  and the speed regulation to match the ever changing load of our small manufacturing plant. I envisaged the "Power Police" pouncing, armed with electrical measuring devices to make sure we were obeying the emergency directives.  I designed a simple throttle control comprising of two identical synchronous motors, facing each other. where if they both ran at the same speed. the output leaver would remain stationary. one of the motors was powered by a battery powered "Shaving" inverter giving a steady 50 hrtz while the other clock motor was connected to one of the phases of the generator. It did work but due to the heavy fluctuating loads the out put was like a roller coaster.
I finally cheated, by putting three lamps between the grid supply and the generator and when they were all "out" I threw the main breaker and we were co-generating. A highly frowned upon practice due to the possibility of electrocuting unsuspecting grid lineman. In this case how ever. our small power plant could not have remained on line for more than a second if the grid had failed.
The grid stabilized our generator, I opened it up to full throttle and watched the Meter running backwards, which it did most of the time except when our large mill was in "start" mode. I am glad we did not have a visit from the power police.

GF






-----Original Message-----
From: Tony.Batchelor <Tony.Batchelor at tekura.school.nz>
To: 'Discussion of biomass pyrolysis and gasification' <gasification at lists.bioenergylists.org>
Sent: Sun, Feb 20, 2011 9:47 pm
Subject: Re: [Gasification] ideal wood gas engine



Dear Kelvin and members.
This may be my first post to this site, I trust you will all not hope it is my 
ast.
Engine power output is a complex issue,  factors such as the energy density of 
he fuel, the air/fuel ratio that enters the engine, the volume of air/fuel 
hich is able to enter the engine during the induction stroke, and the 
ompression pressure reached prior to ignition and the mean pressure reached 
uring the combustion stroke are just some of the most important factors.  
esides the detailed design of intake manifold and exhaust pipes which influence 
ow well an engine can breathe.
Where an engine is to be run on wood gas alone, it would be better to do away 
ith as many obstructions in the intake manifolds as possible.  The key point 
eing to get as much of the gas/air mixture into the engine. This is one reason 
hy Diesel engines are good as they only have suck in air, as fuel is added 
nternally.  Fuel injected petrol engines come close behind, carburetor models 
re generally more restricted as air passes through the carburetor.
Getting the Air/fuel ratio correct is also vital.  Using a "colortune" sparkplug 
s the best way to really know when you have the correct mixture as you can see 
he flame color within the combustion chamber.
A turbocharger can be used to increase the volume of mixture which is drawn into 
ngine but whether or not they are practical given the possibility of 
ontaminated gas is something I cannot comment on.
The Mean effective pressure within the engine during the combustion stroke, is 
argely dependent on the length of stroke of the engine, the compression ratio 
nd the ignition timing.
he stroke cannot easily be altered but the compression ratio can be changed on 
ome engines by machining the cylinder head.
ltering the intake air pressure, using a turbo or other methods. Such as 
ooling the intake air/fuel temperature.
nd by changing the ignition timing.
f a petrol (spark ignited) engine is run on wood gas or any other gas, the 
gnition timing has to be altered.  In general the ignition timing will be 
dvanced by several degrees, in order to ensure as high a mean pressure as 
ossible is reached during the combustion stroke.
he benefit of using a computer controlled ignition system is that most if not 
ll computer controlled systems have a "knock" sensor.  The purpose of this 
evice is to sense when the ignition of the fuel has caused the pressure within 
he cylinder to rise so high that the remaining un burnt fuel spontaneously 
xplodes.  This results in engine knock, the resulting noise is commonly known 
s "pinking"   Diesel engines knock a lot of the time because the very design of 
he engine is to raise the fuel temperature to point when it spontaneously 
urns.
lder engines that use a Distributor lack the anti-knock feature. Commonly 
istributors have a simple mechanical advise mechanism, to advance the ignition 
s the engine revs faster, and a Vacuum Retard mechanism which aids 
cceleration.  Engines which are subject to varying loads, can benefit from the 
etard mechanism if there is any kind of control valve /butterfly on the intake, 
hich would alter the manifold vacuum.
Anyone setting the timing on an engine with a fixed load-speed, needs to be sure 
he advance/retard mechanisms are either working correctly or have been locked 
p. As fixed speed engines can "hunt" if there is any faults in or if there is 
ny small changes in the loading or fuel supply.
Tony Batchelor, ex, road transport engineer, now teaching physics. Wellington, 
ew Zealand.


-----Original Message-----
rom: gasification-bounces at lists.bioenergylists.org [mailto:gasification-bounces at lists.bioenergylists.org] 
n Behalf Of Kevin
ent: Monday, 21 February 2011 1:06 p.m.
o: Discussion of biomass pyrolysis and gasification
ubject: Re: [Gasification] ideal wood gas engine
Dear Charles
Your stated need is for "about 20 HP" at 1,800 RPM
You should be able to get about 21.4 HP with an engine of 2500 CC (153 Cubic
nches), burning about 19 kG/Hr (42 Lbs/Hr)
It would be very helpful if others could comment on the other aspects of an
ngine.... in particular, the Ignition system, whether Distributor or
Computer Controlled", and the implications of using a Fuel Injected engine,
ather than a carburetor engine.
Best wishes,
Kevin
----- Original Message -----
rom: <bayent at ns.sympatico.ca>
o: <gasification at lists.bioenergylists.org>
ent: Sunday, February 20, 2011 11:32 AM
ubject: [Gasification] ideal wood gas engine


 Content analysis details:   (0.0 points)

  pts rule name              description
 ---- ---------------------- --------------------------------------------------
 _SUMMARY_

 Hi All,

 I have several engines to chose from here for my next wood gas project.
 Going to go ahead with it and just hope the stink has settled form my
 insurance company ripping hair out of their heads. ( hope they are not on
 here.. bugger )
 Besides this is not a heating device so should not count.
 What out of the junk yard specials would be considered ideal for wood gas
 give I Only need this time to come up with 20 hp at 1,800 rpm?
 I have everything in the shop for a Mike clone.
 Spending a few bucks for the right engine is going to be real cheep just
 now.
 I am not keen on stuck valves through pistons. ( it that ever happens...
 never mind )

 Regards all,
 Charles

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