[Gasification] small scale gasifiers for those that need them with engine speed controllers

Thu Jul 5 20:55:17 EDT 2007

Controlling an alternator for the output of a steady frequency, say 60 
hertz is 
relatively simple. or you could purchase a car cruise control.
You order up a couple of synchronous gearbox timer motors from Surplus center.
http://www.surpluscenter.com/sort.asp?UID=2007070423332521&catname=electric&keyword=MTSM
Item 1055-D @ $0.89c each.
These motors are identical, with an output shaft turning @ 16 RPM.
You will mount these, ?with each shaft having a thrust bearing attached.
there will be a central disk with an actuating arm inserted between these two motor driven bearings.
?Provided the motors are urged toward each other by a suitable spring. the sandwiched actuating disk
will be locked stationary in between them .When one?OR the other motor is?energized. the actuator disk will rotate ,
at a lesser speed in the direction of the energized motor.
If both are energized, the actuator will remain stationary. 
The motors are synchronous, there for, if one is fed with a standard fixed frequency. say, from a small shaver inverter supply. and the other is fed from a phase of the alternator. it will be possible to control the throttle mechanism, using the arm attached to the middle disk of the bearing assembly, ?sandwiched between the two motors, 
The alternator is set at the required speed by easing the spring pressure and moving the arm into the required control position. 
Should the alternator slow down under load the controlling motor will also slow due to the lower frequency. causing the throttle to be?opened by the reference motor driven by the inverter.This closed loop control works really well if the leverage and reaction speed is good.this is dependant upon the size of the balls in the thrust bearings. together with the motor type, and the way its put together. mini timing belts could be employed keeping friction to a minimum and linear movement instead of an arm. I ran one of these controls for eight hour shifts and the electric clock, driven by the main bus was only one minute slow.

-----Original Message-----
From: Kevin Chisholm <kchisholm at ca.inter.net>
To: Discussion of biomass pyrolysis and gasification <gasification at listserv.repp.org>
Sent: Wed, 20 Jun 2007 10:54 pm
Subject: Re: [Gasification] small scale gasifiers for those that need them

Dear Peter

Peter Singfield wrote:
> At 04:49 PM 6/20/2007 -0300, Kevin Chisholm wrote:
>> Dear Peter
>>
>> Given that he has an engine built for constant speed governor operation,
>> and a 5 kW AC generator already in place, how would you suggest that he
>> "go to DC?"
> 
...del..

> 
> As voltage goes up -- the battery charge amperage goes up -- 
> 
> The DC Permanent Magnet Alternators are 90 to 95% efficiency. 

That is true. You didn't mention Permanent Magnet Generators... you were 
talking about DC welder generators.
> 
...del...
> 
> The entire process is finished in a few hours -- and adjustment is done
> roughly every 30 minutes.
> 
> Yes -- it could be done electronically -- in fact it is being done exactly
> this way -- to achieve incredible efficiencies -- in the new line of
> Inverter Gensets.
> 
> Want the urls Kevin??

Yes, please forward them to the List.
> 
> Anyway -- they use a PM DC alternator to charge a battery - -and the
> inverter runs from the battery. But it is a small battery -- just enough to
> handle surges and make up for governor lag.
> 
> The big advantage in fuel savings in these units is the on the roll
> derating that can then be accomplished -- smoothly.

I question this. I have never yet seen an engine that had a Specific 
Fuel Consumption that was better than the SFC close to rated output of 
the engine. This "sweet spot" is usually at 80% to 90% of maximum rated 
engine speed. Everything I have seen suggests that running at 
significantly lower speed and at significantly lower % of engine power 
rating will drive up the SFC significantly, and result in worse fuel 
economy than if the right engine had been selected in the first place. 
Do you have any URL's that show differently?
> 
> On to your next "question"
>>> Charge rates will govern your engine's revolution.
>> Wouldn't he have to junk the present mechanical governor and replace it
>> with a new electronic governor?
> 
> I your land -- yes -- but here we find electronic components are a much
> added extra expense -- and just one more item to fail -- which they tend to
> do in the tropics more rapidly than in Canada.

If the mechanical governor that was supplied with the engine is not 
capable of the degree of regulation required for good generator 
operation, what is his alternative, other than purchasing an electronic 
governor?
> 
> Reg is in the "tropics" -- by the way.
> 
>>> That is how we are doing it here -- with diesel engines and DC welder
>>>? generators.
>> Isn't that a step backwards? Why not use a battery voltage regulator
>> that shuts off the charger when the battery is up to voltage?
> 
> Another topic that takes much explaining -- -
> 
> To totally charge a battery -- top it off -- so to speak -- you must spend
> long periods trickling a minor charge in.
> 
> We here are doing fast charge cycles only. Couple of hours -- max.
> 
> We also do not discharge the battery packs more than 30% -- else they do
> not live long --
> 
> Further -- they reach full "fast-charge" basically always after the same
> run time -- so it is not feeling the battery for 2 hours straight -- but
> just at the two hour point. If not warm -- let it run another 15 minutes --
> feel again.
> 
> In practice they have their children trained to do just that -- and turn
> the engines off -- "when".

A charge controller would be simpler and more reliable.
> 
> 
...del...

> 
>> If he went to a 5
>> kW DC generator, he would have to get a 5 kW inverter. I cxannot see
>> where there is a potential for a "great increase in efficiency." The
>> cost of a 5 kW inverter would be excessive.
>>
> 
> I do sell 3 kw inverters (6 kw surge) for $370 US here -- 

These are probably square wave inverters which I understand are OK for 
tools, except that they result in less efficient tool motor operation, 
but which can cause problems with computers and electronic equipment.
> 
> But in real terms they never use more than what a one kw inverters? -- the
> ones I sell here for $110 will run your standard skill saw -- thus all
> drills -- grinders -- etc -- a small washing machine -- one of those energy
> efficient small freezers I import (90 watts) -- CF lights -- and a fan or
> two or three.

Peter, you are basically telling him to start from scratch with a new system
> 
> Mind you -- you do have to do load sharing.
> 
> Reg says one KW would be fine for him -- (Oops -- we have been chatting
> "off-list" as this is -- by the way -- all off-topic (according to the
> "rules") stuff)
> 
>> I would think he would be better off to fix his existing Governor, and 
>> if that is not possible, then replace it with an external electronic 
>> governor and throttle actuator.
>>
> 
> I made up a governor that runs off the shaft of the generator -- that works
> well to.

Is he going to buy one from you? Will it give the preferred +/-3% or 
better speed control that is preferred for generators?
> 
> My concern is fixated on conserving energy -- and by conserving energy we
> find we do not need go to the headaches of using a gasifier -- as we reduce
> energy costs to such a great extent the price of diesel then works out to
> the same -- as saying -- 1990 -- and using an inefficient 1990 system.
> Following me??

Regrettably, I don't follow you. He has a gasifier to produce fuel gas 
for his engine. How can he eliminate the headaches of the gasifier??
> 
> Kevin -- in the set up I produce here the engine is run heavily derated as
> well -- it is all "adjusted" by pulley to belt drive ratios -- 
> 
Have you ever run tests to show the Specific Fuel Consumption in terms 
of gms fuel/hr per kW of output on your de-rated engines?

Best wishes,

Kevin

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