Hot reactor lid/ engine connection
Posted 09 March 2010 - 08:06 PM
I just ran the gek with the people of Las Cañadas (www.bosquedeniebla.com.mx <http://www.bosquedeniebla.com.mx>) and we were very happy to do it. It feels great to run the gasifier and produce gas out of wood. But after 45minutes we began to worry, because the temperature in the combustion zone reached the 900o C and the upper lid paint start to peal away and there was some smoke going out of it. So we fire it off closing the gas outlet faucet and let it cool down. The temperature on the bottom of reduction reached 612o C.
Where this temperatures ok?
What are the desirable temperatures in these zones?
Next week I will give a chat about the wood gasification in one of the courses of Las Cañadas, and we will try to start up a gasoline engine on syngas. So, if I understood well, the only change to the engine is to connect the syngas output to the engine air inlet. Is that correct? Or did I miss something?
Posted 09 March 2010 - 08:07 PM
The failure mode that you experienced will tend to happen when there is no raw biomass in the combustion zone. The temperatures will rise at the constriction because there is less energy being spent on thermally cracking wood tar and will dump to heat. The temperatures at the lid will rise because there is no 'insulating' biomass between the hotter temperatures experienced in near the reduction bell and the lid itself.
With no biomass in the pyrolysis zone, the oxygen let into the reaction will start to facilitate in the combustion of the charcoal and possibly any gasses at the top of the reactor which will exceed the temperature rating of the paint used on the lid.
When the lid exceeds ~150C or so this is is sometimes an indication that raw biomass needs to be added to the reactor.
Do you you think that this could have been the case in your situation?
For the connection to the engine:
-connect a valve to the T-cross plumbing piece in the ejector venturi assembly (1.5'')
-use a flex tube as the gas line to the engine (1.5'')
-modify the air intake of the engine so that you can add a 1.5'' pipe connection to the manifold
-completely seal the modified air intake manifold. (Note: There is typically an air filter in the manifold; include it in the assembly. You want to modify the manifold in such a way that you will have access to it later).
-use a plumbing T connection to attach a 1'' valve (ex: butterfly valve). This will be the air mixture for the wood gas.
-Note: Condensation will form in the lowest points of the gas tube, either make sure that the filter is the lowest point, or there is a trap before the engine.
Posted 09 March 2010 - 08:08 PM
Thank you for the information about how to connect the GEK to an engine; I’ll send you photos when I finish it.
About the run, what you say sound me logic, cause it happened after 40 minutes of running and we didn’t add any material during this time. But then, can I open the port hole in the lid to add biomass during the run? Is it not dangerous?
Here is a video about the genset running on syngas during the workshop.
Thanks for everything
Posted 09 March 2010 - 08:29 PM
This is one of several reasons that I like the drying bucket and auger system. The auger will fill the reactor as the fuel level sensor detects that the fuel level in the reactor is low. This is much more convenient. It also helps sustain the temperature profile ideal for the reactor. When the reactor lid is taken off, it lets a lot of cold air into the pyrolysis zone and can sometimes bring combustion up toward the top of the reactor.
Thanks for the video link, please do send us pictures and videos of your wood gas engine set-up and run!
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