haha sorry i’m killing time at work here, brain isnt right when im here…
1 Like
Thinking about building a char bed and stuff like that…lol
Hello Gary .
I was holding my breath and keeping my fingers crossed but I knew if it could be fixed it was in the right hands.
On another note this time next week I should be somewhere midstate Indiana 
1 Like
A great job of group diagnosis. Some of the best brains and brawn in the good old U.S.A. Happy Motoring Gary.
1 Like
Hi Steve U; Got a question that has bugged me for some time, but it came back to light at Argos this weekend where I saw so many WK builds and heard discussions on condensing the steam back to water and how to get it to flow.
A few builds ago I had the hot gases from the grate, come directly into a housing around my hopper. I didn’t get to evaluate it, because I saw I needed a bigger hopper and eliminated the heat chamber in the new one.
My thinking is to use the super heated steam instead of cooling it and getting rid of it. The hot gases would heat the steam to 600+ F ( essentially heat we get rid of in the radiator pipes). Then run that back through the char bed and make H and O2 out of it. Some of the O2 could mix with the C and make either CO2 being exothermic or CO being endothermic. H and CO would add to the gas and the CO2 part would make up the heat required to break the gases down. A big plus would be you get more gas without adding any N.
If you could put this to “bed” for me I probably would enjoy my sleep more.TomC
Can’t wait to hear Steve’s opinion.
From a rookie’s point of view first problem would be separating steam from the gas without cooling. You could boil water in a heat ex but that would require a pressurised boiler to achieve temp above 100 C.
My guess is that a wood gasifier’s charbed already is processing as much steam as it possibly can. In a charcoal unit some extra moist can be added due to dry fuel.
Please correct me. I might be totally wrong.
This.
Don’t confuse water vapor with steam, they’re different and have very different energy potential. With a monorator or WK style hopper we’re condensing water vapor before it becomes superheated steam, which is a major energy burden for the hearth.
Wouldn’t water vapor slipping through down to charbed turn to steam rather fast? Best monorator in the world couldn’t take care of all the water. Yes, it steals a lot of energy boiling water.
Chris,
Water vapor does not equal steam? Can you explain that to me? The major energy burden part I get, but not the rest,
Stephen
I guess I worded that badly. Water vapor doesn’t equal superheated steam. Steam exists in many different states, but the one Tom is talking about is superheated, ie dry. The steam in the gasifier is largely “wet steam” which is low-energy water vapor that needs significant heating before it can contribute to gasification.
Simple math-wise Thermal-dynamically both JO and ChrisKY are correct.
The additional heat you would take out of the HOT glowing active char bed to do the last of the temperature boosting bit to bring that steam up to effective thermal disassociation would temperature quench the char to too inactive.
But.
But.
On the Yahoo ActiveWoodGasBilders Group site back in ~2008/09 along about post # 1500-1700 there was a Finnish newpaper article put up about a Finn vehicle gasifier guy doing just what you propose. Most the modern Fin builder are useing a multiwall produced gases to inlet air complex “W” flow hearth. This was derived off of thier "government"Univiersity VACOLA system.
Seems this private guy has suffered an inner lower walls burn through allowing entry of his heated to steam condensate directly into his char bed. He got better engine power with a reduced chipped wood fuel consumption.
On his next build/repair he then built to encourage this reaction.
He was keeping the actual details very close to the vest probably hoping for a patent and $'s licensing.
His results were witness by credible gasifier guys.
One down side of his system seen was it would only then work well on wet wood chips. Not on dried down chips.
I think the overlooked fact was just how effective hot glowing wood char is at ripping heated to dry steam apart.
The water-to-gas shift. This take far less thermal energy that a strictly heat driven disassociation.
I actually did some modeling of this in my woodstove (out of nesessity!) a couple of winters ago with 40-60% by weight wet wood. Ha! Put up pictures even. No one would believe my numbers. What a PITA operated having to every 30 minutes add small amounts of the wet wood sticks to get this moisture vaporization shift, the steam molecular ripping, those gases burning, char re-generating replacement without thermally crashing the existing hot char bed.
While I think this could be made to work. I think it would be a must keep in a narrow range of wood fuel moisture, versus system heat-load, versus engine gas demand to keep in stable operation.
I will always personally sacrifice the Ideal, for all seasons, all wood-fuels, all engine loading capability flexibility .
NICE she can bake a cherry pie. But you will live on her soups and stews.
Regards
Steve Unruh
6 Likes
Hi Chris,
I absolutely agree that wet or saturated steam is not the same thing as dry super heated steam. Thanks.
Stephen
Thank you Steven for the Sub sandwiches. They were enjoyed by all.TomC
1 Like
Thanks Tom!
I am glad everyone enjoyed it. 
Stephen
1 Like
I always understood as Cris and JO point out. You can’t pour water on glowing embers and expect the O2 to disassociate from the H and then combine with the C and have a net endothermic reaction. However taking the “heat of vaporization” out and wasting it in radiators and then haven useless condensation to get rid of sticks in my craw. And then there is that ugly N guy that is always killing a good party and won’t stay home.
So Steve, “dreaming” on----- you are suggesting that “possibly” if we pulled the steam off the top of the hopper and pulled it down a chamber in contact with the chamber of hot gas, to the nozzles and injected it through the nozzle, it would get the break down, I am suggesting??
I thank everyone for the replies, and I will probably drop the subject, because I am a get-r-done type guy and can see that this is leading to a “theoretical” discussion, which is getting more involved, than anything I could build.TomC
Hey TomC. the best formal writings of this all that I’ve read is the 1974 publication by Niel A. Skov and Mark L. Papworth that was oringinally titled “The Pegasas Gasifer”.
Here on the DOW in the Library section by permission of Dr Paul Anderson as, “Drive On Wood: The Lost Art of Driving Without Gasoline”.
They do use maths proofs as explanations to their real-in-life-use, seen experiences.
Larry Dobson also know these proof uses well to with his up to 60% moisture chipped wood fuel gasifing close-coupled heaters.
HE says doing this that he still got gallons of after gasification condnesate.
I never clained in my wet wood stove adventures that I wasn’t sending the majorty of the above 10% excessive wood moisture as 150F vapor up and out of my 26 foot tall chimney.
The Finn fellow was still observed to have lots of downstream condensate too.
IF only a small percentage of the heat energy lost carried out downstream and normally thrown away could be retained in-system as water-to-gas shifted, then that is an overall gain.
Skov/Papwoth are the best as classifying gasifers as thermal surplus types as in fossil coal, coke, and charcoal fueled types; versus thermal insufficient as in wood and peat fueled types.
WayneK and others now putting IC engine waste heats energy back into their wood gasifiers helps out with this “thermal insufficiency”.
a UK wisdom been quoted to me: “Different courses, for different horses”.
Reagsrds
Steve Unruh
1 Like
I lied! I’m back. Just road the lawn mower for a few hours and that is such a mundane job that it allows me to think ( not a good thing)
Anyway Cris and JO kind of make good sense. You can’t pour water on hot coals and gain temperature. But then again you can add steam to hot char and gain power. We say we do it in a gasifier to a point. Then JO mentions you can add water to charcoal— because the charcoal is so dry. Sort of but not quite. We add water to make an endothermic process which cools the coals down AND makes the additional gases I am talking about. JO makes the point that a gasifier is processing all the water it can handle. Is it??? We do nothing to control the temperature in the grate area. I will start my truck anytime I get the grate above 900 degrees. I feel that is enough temperature to crack the beloved tar and the other gases also. Going through Chicago the other night with semis passing me on both sides I had my boot in it. The grate was approaching 1500 degrees. At that point I would have loved to add a little water. I took my boot out of it hoping one of the semis didn’t suck my door off going by. The point is I think it could have used added steam/ water and besides cooling the grate it would have produced more gas So, I conclude that above 900 degrees we could stand to add water/steam ( of course more steam than water )
So up to here I’m back probably in the theory mode, but unless I get shot down at this point, I have started a design to do this in my mind If it is feasible is there enough benefit??? TomC
2 Likes
Sorry, I meant CHRIS. When I type your name I have to think is it K or C, then I screw the rest up. No disrespect meantTomC
1 Like
Working night at the mill. Just had to log in to see what more has been said
Makes sence. Gasifier can probably handle bit more water when really hot. I read though, from finnish (or was it swedish - don´t remember) research in the 70s on Imbert / SMP units, that very little reduction / endothermic reactions were taking place below 800 C (1472 F) and none below 600 C (1122 F). So you´d better floor it
“JO makes the point that a gasifier is processing all the water it can handle. Is it???”
I was just assuming that as long as you´re collecting water in your “rear tank” you still have enough (to much) moist in your wood (even after collecting hopper juice) to leave steam unconverted (due to lack of temperature).
I understand that adding superheated steam without stealing heat from the charbed is someting else. Just don´t know where to get that kind of heat, since Steve claims even the heat in the heart isn´t enough.
Tom, please don´t stop thinking. As long as thoughts are about fun - they´re good
Thank you JO. I guess you have made enough points that I will put this subject to bed. I should know better than to think, with all the many intelligent people who have worked and written about wood gas, that I would come up with something revolutionary. I got out my old Babcock and Wilcox book Steam it’s Generation and Use but they don’t talk about chemical reaction with reference to super heated steam It concerned me where you said, 1122 to 1472 F was the range for reduction reactions. But as I think about it, my thermocouple is not in the char bed. It is measuring the heat of the gases coming off the grate.
I guess I’ll go back to thinking about a small "swing blade " saw mill. When it comes to running small engines, people go to “pellets” or charcoal and some try “chips”. I want to work on making wood chunks in the range of one inch cubes or smaller. Cars over here are getting smaller and smaller engines and WK and most other wood gasifiers, are way to big for these cars. Don Mannes did have a car there this week with a 1.6 L engine running a down sized WK. He did an excellent job of fitting it in, but I think an off shoot of an Imbert on miniature wood chunks could be fit in a more confined area. One fellow was running a garden tractor type lawn mower on pellets, but there are some draw backs to them.
Oh well seeing you have convinced me we can’t do anything better than condense the steam and dump it out, I’m going to put myself to bed. Thank you for your thoughts.TomC
1 Like