Hi, I have been interested in the topic of gasification for a long time but never really able to put any actual work and interact with like-minded people. So I’ve only been looking around schematics and theory on the surface.
The idea in the title starts from nitrogen in the air and how they end up in the final product.
The air used for gasification contains one part oxygen with 4 part nitrogen, thus the exhaust of the combustion chamber also have them, lowering the fuel’s heating value. Separation these gasses are not easy process.
One could dry distill cellulose fuel in its own vessel heated with air fire. The charcoal left can be used to heat the next vessel. The products can be quite complex, and the heat transfer is very limited by the barrier with little air convection.
Water splitting with hot coal (H2O+C => H2 + CO) on the other hand has purer input and results in purer output, however this process is endothermic, requiring heat inputs for the coal and steam, and temperature above ~700 Celsius and water source. This was done usually by periodically reheat the coal with air combustion between the steam phases.
What if I can collect water from the exhaust by cooling, then make it hot again by heat exchange with the exhaust, the combustion chamber, finally react with hot charcoal in the outside chamber to for fuel and continue the cycle?
Here is a crude drawing for the planning.
There are some challenges that I can see with this plan without crunching any numbers.
- Compatibility with non-charcoal solid fuels: Cellulose feed stocks may introduce tar build up and caustic elements into the turbine and heat changers, and these complex component are hard to DIY so the longevity and maintainability is at risk.
- Water loss may still be significant as <100 degree Celsius exhaust or even ambient temperature can still contain a lot of moisture. May not be practical with more heat exchanger to bring down to near ambient temperature and desiccant cycle to adsorb it all.
- Continuous refueling into an anulus chamber. Need auger all around or some stirring mechanism to spread around.
- Controls with temperature, pressure.
What do you think of my idea? is this overly complex or unnecessary?
Personally I think it’s unnecessary. You learn to accept or get around the perceived power losses that gengas makes. It allows you to increase engine compression, advance the spark timing, etc.
Even in my stock 80hp 4cyl Mazda B2000 truck I was able to get down the road at highway speeds using a charcoal gasifier.
You have to think about it in an economy of size and weight. Will these things make the power gains worth the extra weight you have to carry? Or space that it takes up for a static usage? Or the addition of more parts you have to maintain and replace, things break at the worst times.
Welcome to the forum, check out some of the posts of charcoal powered generators and vehicles!
I definitely see the potential for static use with less storage used up by nitrogen. Do you remember your first woodgas/charcoal related project? I am planning to build a stove first.
I jumped in headfirst with an updraft charcoal gasifier to run the Mazda after browsing and reading up on other’s experiences with different designs.
Trust me on this, don’t worry about the nitrogen in the gas, it helps resist knock in the engine.
Also I’m not sure what you mean by storage, there’s not really many efficient ways to store gengas or at least compressing it. You’d need an industrial setup to safely compress it, so you’re limited to a Gasometer which can only hold so much. Then you have to worry about hydrogen degrading any steel components.
Welcome. And an interesting setup. If you want this to work in the real world , you have to think big. Thermal efficiency of the turbo sucks. Do your math and you will find out. Nothing beats a IC.
If you want to go along, place your condensor before the burning chamber. It saves a liitle energy. And try to cool the rest under 60 deg C.
But again, better stick to a normal IC and start reading. Simple Fire is a good start. Woodgas is difficult enough on its own. No need to make it more complicated.
Welcome to the site Coldice. The inclination when starting to explore wood gas is to over complicate. Believe me, I was the poster child. Everybody recommended that I keep it simple. The more I learned the simpler my systems became. I only work with stationary engines with charcoal fuel so that gets real KISS. Good luck. Keep building and I bet you will end up in the same place.
It looks complicated, but you might just try adding oxygen, and be done with it. You can do it with a membrane fitration or zeolite filtration. The membrane fitlration, you probably be best served just to use the by-products of membrane nitrogen purification. which is like oxygen, argon, co2, etc.