Notes from Windward: #70
A Gathering of GEKs in Berkeley
Opalyn's pics from a
recent gasification workshop
[note: GEK stands for Gasifier's Experimenter's Kit. It's an evolving gasification platform intended for use in an open-source experimental environment.]
One rainy weekend in February '10, All Power Labs provided an outstanding opportunity to learn the art and science of Gasification.
Jim, Jess, Jay, Bear and the crew at All Power Labs provided a weekend gasification conference running multiple projects simultaneously for over 50 people from around the world.
The workshops included:
- assembly of a GEK
- introduction of/to the BEK
the Biochar Experimenter's Kit
- the GEK Skid
mounting a gasifier, an internal combustion engine and a generator on one pallet
- the Lister Project
modifying a single cylinder diesel to run on woodgas
- Upgrading an early model GEK
our original GEK, serial number 004
We started the conference on Friday evening getting to know each other and reviewing the basics of gasification including the chemistry of the processes at work. There were folks there who'd traveled from the Philippines, Ireland, Africa and South America, so it was a fascinating cross-section of folks interested in the rebirth of gasification.
Saturday morning we were introduced to the various projects then turned loose to work on the one(s) that interested us the most. For me, that was the upgrade project since it was my GEK that was being upgraded.
Jim, Jay, and I discussed which parts needed to be upgraded and decided that a total overhaul/replacement was in order. My GEK--serial number 004--would be inducted into the GEK Museum and I would return to Windward with what is essentially an entirely new unit. The only major pieces to be transfered over would be the internal heat exchange lines.
Jay and I discussing the change over as we open up my gasifier
the upgraded gas cowling and reactor chamber
The gas cowling (insulated and shielded)
with the new cyclone attached on the left
While parts and components were collected, painted, and assembled I headed inside to weld several fittings onto the 16 gallon drum that will become the new filter unit.
Steve from New Jersey gives pointers
as I weld fitting to the filter
One of the key improvements we're incorporating into the upgrade is the new hourglass reduction bell. It features a thermocouple tube which allows a temperature probe to be inserted close to the char bed. That's the critical zone, the place where tarry gases are broken down into clean woodgas.
The process of cleaning up the gas is endothermic (it consumes heat) so keeping this particular zone hot enough to make that happen is very important. The thermocouple allows us to see into the very heart of the gasifier and know that things are as they should be.
the new hourglass reduction tube
Here's a shot down inside the gasifier. The pink cloth is just there temporarily to keep the vermiculite insulation from getting out of the space between the gasifier's inner and outer walls. You can see three of the five air injectors where they sit just over the lip of the reduction bell. There are an odd number of injectors so that the air stream from one doesn't strike the injector across from it.
To the right of the inner chamber, you can see the lighting tube. The gasifier is lit using a propane torch with the flame directed down this pipe to the charcoal bed. The gasifier operates at a negative pressure, so in effect the burning propane gas is sucked down into the charcoal.
the inside of the reduction chamber
A key feature incorporated into the upgrade is a double-walled fuel hopper that uses an auger to keep the main gasification compartment filled. The double wall of the hopper uses heat from the producer gas exiting the gasifier to preheat and dry the incomming wood chips.
mounting the auger/hopper assembly
that's me holding the motor
as it's bolted on to the auger
The early GEKs used a paddle-bladed fan to draw air into the gasifier. It took some time for the gasifier to get hot enough to produce clean gas, time during which the fan's paddle could become coated with tar. When that happened, it needed to be stripped down and cleaned before the next time the GEK was fired up. Wood tar makes a tenacious glue for sticking metal to metal.
To solve that problem, a venturi based system was developed that uses a stream of high pressure air to draw air through the gasifier and feed it to a burner. Tarry gas burns with a yellow flame, but clean gas burns with a blue, almost invisible flame. Once the flame "cleans up," the producer gas is ready to fuel an internal combustion engine.
various venturi parts
the assembled venturi gas pump
with the small orifice in place
Jay with the ejector venturi, swirl burner, and plumbing assembly--ready to attach to the filter unit
Another key improvement involves adding a 16 gallon final filter unit which uses a fluidized bed of wood chips to remove tar from the gas stream. When the wood chips start to get "tarred up," they're safely and easily disposed of by being added to the hopper and burned up in the gasifier.
No special filters need to be bought. No fouled filters to be disposed of. It's a really sweet solution that Jim and crew came up with.
the black drum is the new filter
the burner-venturi assembly
mounted on the black filter drum
Jay and I finishing prep work
and about ready to fire off the GEK
Some walls at All Power Lab were decorated with interesting sayings. One that I found intriguing was, "Debussey understood that a work of art or an effort to create beauty, would always be interpreted by some as a personal attack."
This conference was a fun learning experience for me and I want to thank everybody who participated in the workshop and helped me get my upgraded/new GEK up and running--it's now GEK No. 158. I was thrilled and honored that my newly upgraded GEK was used to power the Lister 6/1 diesel engine that Ken, Mike, and many others worked so hard to get converted over to spark ignition!
Click Here to see a video of my GEK powering the huge, single-cylinder LIster engine. At 0:12 into the video, that's me in the brown welding jacket!
A heartfelt "Thank You" to all who made the weekend's success possible!
Notes From Windward - Index - Vol. 70