Wood Gasifier Design

Hi’ya there you go Martin.
A beginning of stated goals will get you usable inputs.
American old cast iron inline sixes were some of the best for generation/pumping service. Why Onan used them (Fords) on thier tow behind big gen-sets.
PartickJ. here on the DOW down in South Africa has used a Chevy inline six to woodgas fuel electrical generate most recently. Read his “Woodgas in South Africa”.
Yes the Dodge/Chrysler slant six was near indestructible. Expect at a generator duty 1500-1800 RPM an electrical solid 20-30 kVA possible on gasoline/propane/methane. A fellow on a DIY forum small engine group got this off of his basement unit with street gas conversion handily. Woodgas fuel do not expect at that low of RPM with that low of energy fuel base more than 20 kva.
Once developed in you would have an hourly wood fuel consumption in the 20-40 pounds per hour useage. Even system electrical unloaded this would still be at least a 10 pounds per hour wood use system to keep everything up hot and running. Standby energy use on generation systems is a real killowatt(mechanical) fuel consumption drag.

So . . . see why the importance of “Where are you going to get your wood fuel? How much can you sustainable actually get? How much are you willing to on-hand work sweat-it into gasifier useable form?” ALL can be figured from the get-go before sourcing/cutting/welding sweating the metals.
WayneK and PatrickJ both have commercial lumber mills with made edge trim wastes. Tons daily. Cubic meters daily.
Good news is on a larger engine application like this slant six you only have to eat the wood down to 4-6" chunks.

I have for the past 40 years been sweating at last 30 000 to 50,000 pounds of wood annual for our families for heating purposes.
So I just wanted to go wood use a small 5 kva for a woodgas electrical generation system. Sigh. Means treewood sweated down into 2 inch chunks with our Douglas Fir. Or fully chipped and sorted. Or all ground up to dust; then into woodpellets compressed.
So my trials have been to make, buy, source a system able to either cord/stick wood gasifiy; or for this small of shaft power needs be able use the big vehicle sized chunks.

Regards
Steve Unruh

Lots of good info there Steve. I like having you around as I don’t think I could have said it that well.

For an imbert type gasser that would be a 4" restriction.

Thanks for the detailed information Steve. The numbers that you provided will allow me to do some project planning. Thanks.

Good Day Martin
“What design parameters are important, and what are pretty well set?”
Now with a stated possible cast iron six cylinder engine to woodgas electrical generate this can be explained a bit. (Be much better if you would fuel wood type and process sizing declare also)

A wood gasifier is a make solid fuel first into HEAT; then that heat converted into gasious short chain chemical stored energy’s for use as potential motor fuels. Two steps.
This slant-six engine is a take liquid/gaseous fuels chemical energy’s and turn them into heat AND PRESSURE, to then mechanical shaft energy converter. (two steps here also)

Very, very well decades, use-tried documented that wood fueled gasifiers will be at best be ~70% (-30%/+2%) efficient doing this solid wood energy to gaseous fuel energy conversion.
Woods will lab test out at a rated 9200 to 7000 BTU’s of fully burnt heats worth of energy. Same numbers are available in Kcals per kilo, calories per gram.
I just use a reasonable easy to achieve 5000 BTU’s per pound of system wood-in practical useable converted.

IC piston engines range from 20-32% efficient converting their fuels BTU rated energy into shaft mechanical useable energy.
Gasoline is a seasonally mix rated +/- just north of the 100,000 BTU range per US gallon. Imperial and metric ratings on this also available.
So an engine/generator system that would use 1/2 US gallons of gasoline per hour would need a woodgas system capable of handling/converting 10 pounds of fuel wood and hour.
Fuels BTU comparisons are horribly over-simplistic in comparing engine systems. Way too many secondary variable factors in there. The most important is just how well that engine design IS at match-converting the actual used fuels variable in-cylinder pressure rise into rotaing shaft power. Eg bicycles. The same YOU not nearly efficient if I take away all of your gears down to 3; shorten your peddle crank arms and lower your seat to cramp up your knees. Banna bike you will just make lots of heat, noise and motion and get left in the dust versus a 10-21 speed set up for your height and leg length.
Woodgas to diesel/gasoline/propane/methane system use is not possible to compare fairly.
When you run 200 US gallons equivalent in 4000 pounds of wood fuel through you will have at least 40 pounds of mineral ash, 4 pounds of soots and from 400 to 4000 pound of condensates to deal with.
Ran on pump gasoline for 200 hours just a couple of three oil/filter changes.
All that fuel’s stocks base ashes, moisture’s and acids were left behind at the petroleum fuel refinery.
Ha! Alone with the heats it Did Take to cook down/crack and reform build back up into the spec gasoline components!
YOU: being the base fuel (wood) “refinery” with woodgas, right up next close and tight to your engine heat consumer can archive full cycle efficiencies to make them blush. You will full cycle beat electric car full cycle efficiencies.

This takes systems/integration thinking right from the get-go to achieve. Integrating you can turn individual step problems into next step easy solutions.
“Systematic” thinking . . .developing one system step complete to ideal at a time is the long, never get there rabbit hole. The Ideal hearth; → then the Ideal filtering; → the Ideal engine; → then the ideal generator head approach is why most quit in frustration.
Even worse is if you are experienced expert in one step and then use narrow focuses experts in the other steps. $$$$$, years, and still not a useable system.

Systems/integrations in heats approaches will always kick-ass.
And then you can factor in the freedom fuel multiplier.

Regards
Steve Unruh

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Thanks for the info. Lots of great information to chew on. Anyone live up in the north west around Montana. Would be great to see an unit in action.