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[jimmason]

Here is a slightly modified reactor for the standard GEK that creates an 11" inside hearth diameter, instead of the previous 10".  The reactor shell continues to be 12". This larger hearth is achieved by changing the way in which the inner insulation tube is done, as well as how the bell mounts to the base of the reactor. The wider hearth allows for a wider nozzle ring and wider tapers to the base of the reduction zone.

Previously the reduction cone could taper out to 6". This new reactor will support tapers out to 7.5". This larger taper potential can be used either to increase residence time in the reduction zone with the standard 3" restriction, or to support larger restriction and related tapers, and thus larger total gas flow rates. Our current testing is suggesting that increased residence time in reduction would be helpful.  The change from 6" to 7.5" diameter at the base of the cone is about a 50% increase in cross-sectional area for gas flow.

The pictures here show a full hourglass hearth made to fit this new 11" reactor. Completing the hourglass instead of leaving the top cone to form passively over the standard inverted V hearth base, seems to result in less bridging, as the fuel is on a slippery metal surface, not charash. As we are now using stainless for these hearth elements, and already fighting out making cones, there is no longer a need to use the ash to passively form the top cone. Purpose forming this top cone also eliminates the need for the tar fence, which previously prevented circulation through this ash formed top cone.  Still keeping this hearth mounted to the base, with lots of open space on the sides, continues to make possible the packing of robust insulating around the hearth, with several stages of "walls within walls" to prevent convective heat flows.

The hearth shown has a 4" restriction with 8" height from the restriction to the bottom of the taper. Bottom opening is 7.5". This is a less than ideal taper outwards, but was done to get the max gas flow rate from the standard GEK so as to run a large generator in Costa Rica (where these pictures were taken). With the standard 3" restriction, the same 7.5" bottom opening will create a 1:2.5 taper ratio, which is the direction the accumulated testing is directing towards.  










(note: the little tube on the side of the hearth at the restriction is for installing a thermocouple to monitor temps at the restriction)



There are more pictures of the new hearth in the wiki here: http://gekgasifier.p...11-Inch-Reactor

[jimmason]

i put up more pictures of the 11" reactor and runs from costa rica.  these now include the post run dissection of the reactor and filter.  see here: http://gekgasifier.p...11-Inch-Reactor and go to the bottom of the page.

notice how different the fuel looks down in the bell when using these blocky fuels.  the void space is maintained and progressively shrinking in a manner we do not get with the shells and wood chips.  the pictures show the classic description of what you are supposed to see- progressive size shrinkage as the fuel moves down through the reduction zone.  i hardly ever run blocky fuels like this as i don't find them realistic to make for most people.  most people have and want to run chips.  

you can also see the the larger drum filter we made for this installation, and the condition of its insides after two hours of running.  in short, there is nothing to see!  new metal clean after lots of hard running.  i was very happy to open the top and see this.  and especially on 15-20% moisture content fuel in tropical humid air.

here's the pictures of the filter.  i'll post more on this expanded filter scenario soon.