The GEK is a piece of lab equipment. Its principle virtue is that it can enable people to get off their butts by providing them with a basic workable (and most importantly, hackable!) piece of gear, and start experimenting with gasification and any of the myriad of gasification problems that are out there for us (tar-reduction; gas cooling and cleaning; different fuel types; fuel moisture; reaction zone design; etc).
I think it might be useful to establish a "standard set of conditions" that we could refer various tests to, so that I can reproduce here in New Brunswick some setup that Jim tries in California, and then I can test out my idea on top of his. Then whatever results I've gotten, are meaningful w.r.t. Jim's, and he and everybody else can try working on the combination of his idea and mine.
It seems to me that wood pellets are probably not an optimal GEK fuel (smaller and dustier than ideal?), but they might be a good choice for the purpose of "baselining", since they are a standardize industrial manufactured product that are widely available. Also, they're low and consistent moisture content, and freely flowing.
Another standardized test condition should be fuel consumption rate. I see that Tom Miles used 3.6 kg/hour during his recently reported GEK runs. I am suspicious that this is lower than optimal, and that we should come up with a sensible "standard rate" - it should result in decently-hot conditions so that there's a chance of being able to produce low tar gas, but it should be slow enough that there aren't serious dust ash and particle entrainment problems. Measuring fuel consumption rate is practical over a longer time frame (an hour), but I can't think of a good way to get a nearly-instantaneous measurement of it. I suspect that measuring the input air flow rate will probably be nearly as useful (perhaps combined with a temperature reading or two, just to establish that things are in a sensible zone of operation).
Comments (4)
bk said
at 9:31 am on Feb 8, 2009
Very good suggestion, this is what we should be moving towards.
I haven't worked on it yet, but developing a standard report form for the tests would be helpful too.
Date, Purpose, GEK version, Modifications from Base Version, Flow Rate, Biomass Type, Ambient Air Temp, Results, Photos/Video/Data/Spreadsheets
And yes, wood pellets are likely non-ideal, but useful as a commonly available baseline.
(account deleted) said
at 2:56 pm on Feb 8, 2009
20% of home heating here is done with wood pellets. Users find a noticeable variance in consumption and heat out put due to "brand". Hardwood versus softwood. Binders/sealers used: flammable (gasifireable) versus non-flammable clay. Gravity feed systems have proven too unreliable Because of the too good of flow at first than poor flow when/if the pellets are subjected to any free moisture. A positive mechanical dribble feed has proven to be the only reliable solution the same as with unscreened chips. I believe specialized GEKs can and will be developed to sucsessfully process these fuels. Pellets here will become the Transportation fuel do to their widespread availability.
I recommend sawn up chunked shipping pallet wood as a standardized, available training default fuel. In my fuel production testing the soft wood fir and pine are easily power sawn up in strips around the nails and then hand chunked with a hatchet. hard woods oak and mahogany also saw up with a carbide tipped blade and the nail full chunks converted to charcoal and the nails easily picked out. Yes for information exchange would require two standards.
Because of the small size and weight of a GEK it would seem to me easy to measure total equipment weight change for fuel consumption purposes using three commonly available electronic scales.
Steve Unruh
bk said
at 5:45 pm on Feb 8, 2009
We have one scale in the shop that is in this weight range. Plan is to do runs of the GEK on this scale to determine consumption rate when needed. It also has serial output so could eventually get logged by computer.
Pellet heterogeneity duly noted. I'm not sure what details manufacturers specify (at least ash content and hardwood/softwood, right?). Are binders generally noted or easily tested for?
(account deleted) said
at 9:16 pm on Feb 9, 2009
After a long Internet search the most objective pellet quality info was at the Pellet Fuels Institute www.pellet.heat.org/2/StandardSpecificationWithCopyright%20.pdf A voluntary US trade organization trying to set up measurable/certifiable fuel standards. They are going to allow four different grades NOT based on hard/softwood content or Heat Value but primarily due to ash content (.05% to 6%), Chlorides (salt), sizing consistency, handling durability and Lack of added chemical and inorganic additives. Checked locally and found only one out of five suppliers had stock on a labeled brand as PFI Premium. So quite a bit of variability even in parts of the world where wood fuel pellets are available. The Google map already shows owners in seven areas of the world that I would wager do not have wood pellets: but I'd wager they could easily find a hardwood shipping pallet.
Current fuel standard is needed now for the default Inbert/downdraft GEK. The GEKs modified to effectively utilize wood pellets will be a different beast and could use the PFI guide lines. So yes, different standard for different fuels stocks. A single fuel standard will limit the GEK to being a regional effort instead of a world effort.
My best regards to both of you for the good work you have done and will continue doing.
Steve Unruh
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