GEK Wiki / Troutner Pyrolysis Experiment
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Troutner Pyrolysis Experiment

Page history last edited by Chris Troutner 11 years, 12 months ago

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Before jumping into building my own GEK gasifier, I wanted to explore the concept and relationship of pyrolysis and combustion as described in the How it Works section. This page is as much to record what I did as it is to solicit feedback from the community on my results.



What I wanted to explore was the concept of weather or not combustion is actually necessary in the gasification process. Inspired by the Simple Wood Gasifier YouTube video, I attempted to recreate it using some lessons learned from the wiki and forum on this site.


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Theory of Operation  

As you can see, I have my fuel in a 1-gallon paint can. Now, unlike the GEK, the fuel in this can is heated without exposure to air - so combustion can not take place. From the can, the gases are routed to a small tin can filled with charcoal and dolomite lime.



From reading the forums on this site and doing more research on the internet, it appears that dolomite can act as a catalyst to lower the temperature required to break tars up into simpler gases. The charcoal is at attempt to still run the gasses through the reduction phase - so that any H2O or CO2 from the fuel could still be broken into H2 and CO.


In this way, I hope to remove the combustion phase and achieving tar cracking and reduction inside the tin 'christmas' can. 


In a normal gasifier, the combustion phase is exothermic (produces heat) which powers the pyrolysis and reduction endothermic (absorbs heat) phases. These heat producing and heat absorbing phases are constantly at war with one another inside the gasifier. By combusting propane for this process (such as in the set-up above), the operator can have greater control over the heat used for pyrolysis (and thus gas flow) as well as finer control of the heat for tar cracking and reduction. Also, by separating the processes it allows for better control of each phase. The end result should be cleaner gasses. Once the system is running, the wood gas can be piped back to the burners and the propane can be shut off. 



Test Results

Before I present my preliminary results, let me first say that I recognize that I am trying to do too many things at once. If I really wanted to see if dolomite lime had improved tar cracking ability, I would need to isolate that from the rest of the experiment. The same goes for the separated charcoal bed for reduction, etc, etc. However, this is much more of a hobby project for me than a serious scientific endeavor.



My first test today showed quite a bit of promise. For fuel I used wood pellets as they were readily available and well discussed on this site. At first I only lit the burner under the fuel hopper and left the burner under the charcoal bed unlit. The gas coming out of the nozzle lit well and didn't appear to have much tar or smoke - as would have been the case if I had lit the gasses coming directly out of the paint can. I can only assume that the charcoal 'christmas' can filtered the gasses by cooling it and causing the tars to condense before they made it to the exit nozzle.



Once the paint can was steadily producing gas, I lit the burner under the charcoal bed and gave it some time to reach thermal equilibrium. With the charcoal bed heated, the gas output was definitely reduced. I can't really explain this other than a possible dilution of the combustible gasses by the non-combustible gasses coming off the dolomite. When the dolomite was heated it gave a very strong odor - similar to the smell of sulfur. 



Future Plans

From here I'd like to solicit the feedback of the community. Where do you think I should go? Is this just an effort in futility? Do I have the ideas all wrong?



One thing I definitely want to do next is attach some thermocouples and pressure sensors. If I can monitor the pressure and temperature inside both the fuel can and the charcoal bed, then I'll be able to correlate the temperature and pressures with gas production. Right now I'm pretty much shooting in the dark. I can't tell for certain if I'm getting the charcoal bed anywhere near the 900C mark for the proper cracking of tar (dolomite or no dolomite).

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