I apologize in advance for this, but I really want to know if this is a good idea or just plain stupid.
I was reading the Basics of Woodgas page on this site and I’ve read a lot about wood gasification in general. As I understand it, wood is gasified by heating it in an oxygen-deprived environment which releases water vapor and carbon dioxide. Then, it passes through an incredibly hot area which breaks down the carbon dioxide and water vapor into carbon monoxide and hydrogen, which are both burnable gasses… right?
On to my stupid question, then. Instead of obtaining the hydrogen from wood, couldn’t you just boil water to give off steam and run that through a hot area (heated by char) to crack the water vapor? I’m guessing that my severe sleep deprivation from the past few months has taken its toll, but maybe you could humor me.
It’s a good idea! In fact some charcoal gasifiers actually have water injection systems for this reason, since they have no natural moisture in the system. The process also happens all the time in a wood gasifier. Even the driest wood contains a certain amount of chemically bound moisture, which it will release as steam when it’s burned. Wetter wood makes much more steam. Some of that steam is cracked by the hot char. Generally there’s way too much water needing to be cracked in the hearth, and not enough heat to do it. Which is why you get plain old steam coming through in most systems, and need a good system for condensing it out of the gas. Condensing hoppers, called monorators, are also very useful to head off some of the steam before it goes through the hearth and robs valuable heat.
Designs with a larger amount of glowing charcoal will crack more of the moisture. Designs that recapture a large amount of heat will be able to crack more steam with it. Wayne’s setup has both, and as you can see is quite effective.
What you are describing is making “watergas”. This water over glowing char has been know, and used for at least 200 years to make and use on the spot H and O2 gases.
Problem is it demands you have already produced charcoal from wood or coke from fossil coal.
And you also have per-purified/de-mineralized water. All natural waters including rain water has enough of these to scale coat, clog and heat transfer block your apparatus with any amount of operation time.
So to make these separately on any scale you have expense, waste heat losses and a whole load of very nasty “wastes” refined and separated out to now deal with or dump, ignore and leave for a future generation to deal with.
Very glad you caught the H2O and CO2 through glowing char reduction step. You have however over simplified and missed the heat cook from the wood the long chain HC’s (“smoke”), wood water and HC oils with the HC’s then being oxidization zone torn apart into the shorter chains and that now super heated for further thermal/chemical “reducible” HC’s and super heated water vapor for the next step you have described.
Beauty of a good raw wood fuel gasifier system is it most efficiently takes all this and much more into account without having to over think it.
Most efficient way to take your own on site grown wood and make a power shaft go around and around and still be able to live with it as far as your own personal labor in and wastes out.
Gotta’ still have time and a personal environment to be able for the really important things in life like hoeing the garden, tending the chickens, playing with the dogs and the children.
Thanks for the replies. It looks like you’d be better off sticking with wood.
@Steve Unruh: I was going to include the aromatic hydrocarbons in there, but from what I’ve read, there aren’t enough generated to be significant. I read that on Wikipedia though, so it’s probably not accurate.
Sure seems I will learn a lot from good people on this site. Have a 454 95 Suburban 4 X 4 3/4 ton that seems like a good prospect for gasifier, just hang it on the back end above the hitch a ways on a swing away set up so I can still get in the back door and more easily have access to the stinger.
Hi JakeSnake, I had a similar thought about “extra H2 and O2”, but my idea(borrowed, of course) is to heat my canning pressure cooker with some of the flare gas and introduce the steam directly into the hearth zone. Still a ways off but I’m going to try it after I finish my latest round of preheat mods.