[Gasification] Prime movers -- The Slow Go diesel concept

[Peter Singfield]

OK folks -- changed the title of this thread -- is that "legal"??

At 09:07 AM 8/1/2006 +0100, Ken Boak wrote:
>Peter,
>
>Thanks for your recent interesting posts on the gasification list concerning
>your Lister activities.
>
>I am intrigued that you are seeing improved fuel economy at 375rpm,  because
>I would have thought that the constant hp losses such as driving the
>injector pump,  overcoming bearing friction and reciprocating losses would
>acount for a greater percentage of the power produced.
>

It has all to due with keeping the engine's operation in the ideal fuel to
air mixture range of ratios.

I have tried to explain this concept -- to many time -- but once more.

If your running a generator at a fixed RPM using a diesel.

Say optimal operation -- injection rack opened to deliver the perfect
amount of diesel to get the perfect air to diesel fuel mix ration -- on
these new model Lister -- 850 RPM -- say that would be giving 5 kw electric
power out (probably more like 4600 in reality)

So -- when the load is 5000 watts the diesel injection rack just happens to
working at the ideal position -- so fuel consumption will probably be at
factory rated specs -- 268 gms of diesel for every kw of power produced at
the crankshaft (of course- - less will be coming out the generator)
(Loveson's claim fuel consumption for their 8 HP 850 RPM model)

Now -- just to keep things "short and easy" -- call that ratio 15 to 1 --
15 parts air -- one part diesel.

OK -- but now your load drops off to 1000 watts -- 1/5 of rated operating
specs -- yet the motor must keep turning at 850 rpm!!

so what is happening??

Well -- the injection rack backs off due to commands from the engine
governor -- and now you have much less fuel -- much more air -- in the
combustion mix ratios.

Lean fuel air mixtures results in engine efficiency problems -- as in you
no longer get 268 gms diesel per kwh on the shaft produced.

OK -- so that is the basic principals involved -- OK??

Now -- in my never ceasing to amaze anyone hard drive archives I have some
JPG graphic files which are exact reproductions of the engine manuals that
came with the original -- well -- to type it in:

Lister Engine Information - 5/1 series -- Page 4

The 5/1 series is our beloved old Lister -- in original 650 RPM -- 6 HP -
-tank or radiator cooling mode.

Anyway -- this page has these lines:

Guaranteed Fuel Consumption per BHP hour:

Full Load = .284 liters

3/4 Load  = .300 liters

Half load = .347 liters

Now -- that is as far as they go -- but my house requires but 800 watts to
run everything -- including my new -- high efficiency -- Chinese made (of
course!!) small freezer - -which for those that might be curious -- will
hold a fully dressed out -- butchered pig -- of up to 275 pound of meat --
and freeze it hard -- in but 12 hours!!

800 watts -- all the lights -- the fans -- the computer -- everything!!

I do have an electric coffee percolator -- and that does jump my
consumption to slightly over 1500 watts -- but only for 15 minutes or so --
once per day.

It does allow me to demonstrate what total power I can achieve in derated
mode (more on that later!!) 

OK -- So here is the deal.

I knew by the old Lister manuals -- and applying the theory of lean
mixtures being less efficient -- that as one runs a diesel in continuous
RPM mode -- but less load -- fuel efficiencies go out the window -- so to
speak.

But how much in real time -- when I am not running at 1/2 load -- but
closer to 1/6th!!

Well -- I decided to "experiment" (I know -- in these modern times of
computer simulations and all those powerfully attractive major "grants" --
a very dirty word indeed)

So I took my Loveson 850 RPM Lister single and derated it to run at 375 RPM.

To make a long story shorter -- I ended up using 1/2 and less the fuel to
serve the same purpose in power my house.

Or to put it another way -- it requires more than double the amount of fuel
to run my house at 850 RPM than at 375 RPM.

Now -- why would that be??

Well -- to me it is a real obvious "NO-BRAINER" --

I am running closer to the ideal cylinder charge -- air to fuel ratio --
thus gaining much efficiency "back"

Ken -- I really hope you can understand the principles this time round??

And for the rest of you people out there -- I have no doubt this applies to
running a genset using producer gas!!

Think of the thermodynamics involved in throttling off the fuel supply at
low load rating -- so less fuel air mixture goes into the cylinder -- again
-- totally unbalancing the engineered specs of that engine -- right??

How so -- well first of all -- your going to be losing compression ratio --
and big time.

OK -- on with the diesel example.

So I emails George at utter power outlining what I was going to do -- he
replied -- you can't do that -- you'll destroy the engine cause your
running it way to slow!!

Well -- how so??

I'm running it to slow -- but at much less the HP -- I am not exceeding any
of the engineered designed criteria -- just slowing down the entire process
-- so developing less HP -- so my rack is more opened when operating -- to
meet a greatly reduced load requirement.

Anyway -- as usual -- they all said it could not be done. That was many
months back -- and it has been done -- and everything works better than
wonderful.

I had to re-engineer the governor linkage -- I now have governor response
much better than in the original design running at 850 RPM -- my Hz varies
less than 1/2 from zero load to full load -- excellent indeed.

I had to put a large flywheel on the generator shaft -- so as not to have
my lights flicker.

I have to apply a little bit of hand soap to the drive belts about once per
week to stop the squeaking.

I figure by derating in this manner I can double the life expectancy of my
engine -- after all -- it is less than half the stroke -- half the valve
opening -- half the piston travel -- half the injection cycles -- etc -- etc.

I is weird to look at a power plant that weighs in over 1350 lbs -- that
only produces 1500 watts -- but hey -- makes it hard to steal to!!

Any way -- I did this "experiment -- for one reason -- and one reason only
-- and now I will state that:

How slow can you go in derating a Lister??

Well -- I can promise you -- one can drop the RPM from 850 to at least 375
with no ill effects --

Now -- why would anyone in their right mind want to know this??

OK -- on to Ken's next paragraph - -then all will be "clear" -- if not to
you folks -- certainly to me.


>I have recently got one of my engines coupled up to a 6kW dc PM servo motor,
>so I can try motoring the engine at different speeds to see what electrical
>power is needed to overcome these losses.
>

Well -- in my "dreams" I would like to run this Lister set up using a 3
phase -- PM alternator in the same manner present windmills do.

That is the AC 3 phase is rectified to DC -- charges batteries -- and then
is inverted to supply the voltage and phases one wishes after -- 

Instead of holding the engine at a fixed RPM -- one then does like the wind
-- blow hard -- blow easy -- 

so -- if I need 5 kw -- the engine runs at 850 RPM -- if I need 1500 watts
-- it runs at 375 RPM -- but always -- with the rack open to the perfect
setting for maximum fuel consumption efficiency.

But -- to do this -- one would need a different type of engine control unit.

I would suggest using a Hz reader -- and clocking the engine in according
to that -- plus minus 1/2 hz.

Think on it -- it will come to you -- I am exhausted dealing with the finer
points -- but with a micro in line -- a stepping motor or other servo
hooked to the rack -- it is easy to do.

>I can now extract dc from the motor, at about 135V, to charge my inverter
>battery bank.
>
>Indeed, at 375 rpm, there is going to be considerable excess air in the
>cylinder. Perhaps this accounts for the improved fuel economy.
>

Other way around Ken -- less air -- more diesel -- closer to the optimum
fuel air ratio.

I know -- hard for people to "visualize" -- but in real time -- it is so.

>Unfortunately, when burning waste veg oil, there is unlikely to be an
>advantage of running at half speed.  I have heard from a colleague's
>experience, that the carbon build up is quite considerable at less than full
>load.
>

Well -- there you go -- tripping over your own thoughts again!!

Ken -- less than full load is the state of air to fuel mixture at a fixed
RPM!!

what you need to start doing is consider the stroke mode -- what is the air
to fuel ration per stroke.

The speed of the strokes per minute has nothing to do with it -- the engine
does not care -- it is all about the load per charge.

Your veggie oil will burn much cleaner in the rpm derated mode because the
cylinder stroke will be right on the full load mode setting then  -- capiche??

>Two weeks ago I recovered a 1953 Startomatic generator set from a house in
>the Lake District, in good working condition.   The alternator is fitted
>with a flywheel  14" in diameter and 2" thick, as well as the 10.5" twin
>belt pulley. This mass, rotating at 1500rpm, helps to meet the needs of
>sudden changes in electrical load, and I suppose reduces the snatching
>action on the belts, when a load is suddenly applied.
>

That appears to be exactly the same size flywheel I use. I ordered some
extra ones up ($12.00 US each) from my last engine delivery from China.
These are the flywheels they use on the single cylinder 6.5 HP water cooled
units.

And something else -- they work miracles for helping with electric motor
starting surges!!

>Looking forward to hearing how you get on with the Chinese gasifiers. It
>would be great if it could be simply connected to the Lister air intake
>through a suitable valve, and make a very simple dual fuel arrangement.
>

I must convert them to charcoal burners first -- with some help from Doug.

I am not aiming for dual fuel though -- pure producer gas -- using glow
plugs for adjusting compression ignition points. I already have the extra
cylinder plugs in hand -- and need but order some model airplane glow
plugs. These I will mount -- say 3 -- in the precombustion chamber "plus"
that screws into the side of the Lister cylinder head. And buy using a
resistor -- adjust the proper power levels.

I will start on diesel -- but once warmed up -- off goes the diesel -- on
goes the glow plugs -- and there one is -- running 100% on producer gas.

So I hope -- 

Again -- I plan on a maximum of 1500 watts -- continuous operation -- power
plant style.

I do sometimes need more power (but at the 1500 watt setting I now can
operate all my present in hand power tools -- including the skil saw) --
but plan to that by starting another generator -- that will run just for
that purpose only -- and always just on diesel or equivalent veggie oil --
or home refined from crude oil -- or cleaned used engine oil -- or what
ever I have at hand that day.

It is much more economic to run two power plants that try to do it all with
one -- and the equipment will also then last ever so much longer --

As far as I know I am the only person on earth at this time with this
"attitude" -- but that certainly might change soon -- once the Muslims and
their friends figure out the best way to bring back sense to you Westerners
is to stop producing crude oil by a large amount -- thus driving the price
up past $200 US a barrel in not time -- worse -- crashing the global
economy to bits -- blowing up the paper (totally devaluating your paper
monies) so that in real terms -- even $10,000 per barrel of paper money
will be cheap.

but then -- probably -- some of you to will learn how to live well with but
1500 watts maximum power -- steady -- 

and you will have to roll your own to -- as I doubt your great utilities
can continue to exist under those circumstances either!!

Till then -- syranada -- eh??

What is your dreams again?? Jim -- you need a very minimum of 15,000 watts
or else death is more preferable -- or what -- eh??

!/10 of that is all I need -- and in the manner I plan to go about -- no
electronics at all -- no batteries -- no inverters -- just a gentle back
beat -- Phaff -- phaff -- phaff -- as in hear the natives drumming far off
in the jungle -- must be they are "restless" again.

I doubt high tech solutions will be viable in the world scenario I paint
above.

But good luck dreaming that nothing has changed in the past few weeks and
that everything is -- as always -- well under control -- and happy days be
here for ever.

Stop in place -- tend to your garden -- and play the future "short"

Peter / Belize

>
>Best wishes,
>
>
>Ken
>
>
>