Scientific, detailed explanation of gasification process

[Northwoodsman]

I've got my EKO40 system working very,very well after approx. 2 months of intense evaluation, data collection, modifications etc.

Although I understand how the gasifier works I do not know the exact names for the chemical process that is occuring here.

Can someone please explain this entire gasification process with detailed, scientific terms (my engineering brain wants to know and understand this process in detail).

Thanks,

NWM

 

[EnCalientesAqua]

This is from memory, but I think I can convey the ideas for you to do more research. Hope this gets you started, but please understand that I have not read up on this in awhile.
The fuel is comprised of sugars trapped by the suns radiation. there are several types of sugars, but you can generally call it all cellulose.
Two stages, and three reactions. The first stage has two reactions: Combustion of wood with O2 oxidizer, the boring aspect of the reaction. But this achieves charcoalizing (pyrolysis greek pyr: fire, burn, heat by, glow + olysis: to break down) literally turning solid carbon into gas. As a side note flaming combustion is not required for charcoalizing, heat is required. You could achieve this effect by putting a sterno under wood chips in a can and get a very efficient release of gas. Often why people refer to gasifiers as wood cooking or cooking wood or distillation.



In the second stage gasification your distilled fuel is CO CH4 N H. combustion of these compounds isn't very thorough in other wood burning appliances or even very common in nature. Primarily because this second stage combustion requires the presence or high temps 2200F and a specific ratio of O2 to gas. The equations for these reactions can be looked up, but it becomes clear that these gases create an exothermic reaction that results in the 30%+ increase in energy output. The ultimate exhaust should consist primarily of CO2 and H20.



This was one of the longest posts in boilerroom history, it had some of the answers an engineer would want to see.
https://www.hearth.com/talk/threads/10679/

 

[Northwoodsman]

Thanks for the explanation firestarter !

I checked out the thread you sent me and there was another good explanation.

NWM

 

[jebatty]

This is better than pretty good.
"THEORIES OF THE COMBUSTION OF WOOD AND ITS CONTROL"
(broken link removed)

 

[Northwoodsman]

Jim,

I just downloaded this paper and it's exactly what I was looking for and then some (I think it will take me a while to go through it) !

Thanks,

NWM

 

[rickh1001]

Northwoodsman,

In addition to the above, Wikipedia has some nice overviews of the process under wood gas and another under Fischer Tropsch synthesis. Pyrolisis would be the right term for what is happening in the primary chamber. It produces a complex mixture of hydrogen, carbon monoxide, methane along with a whole host of tars and complex hydrocarbons, depending on the temperatures and conditions. If you capture the gas, it can be converted to liquid fuels using the Fischer-Tropsch synthetic process, which uses various catalysts to convert the "syngas" to diesel fuel or other liquids. The basic idea of pyrolysis of biomass or coal to gas, then converting the gas to liquid fuels, has been around for a long time, and was used during WWII to create fuels when petroleum was scarce. It is a pretty fascinating area, and is under very active research around the world. Of course, for our gasifying furnaces, the gaseous pyrolysis products are directly burned in the secondary chamber. It is fun to know our little furnaces are right at the cutting edge of technology in terms of biomass utilization.