On Jul 26, 2010, at 5:42 AM, doug.williams wrote: > Reply. The cyclone at best, will pull out dust to a particle size of 10 > micron, that's like talcum powder. You next clue is in the condensate water, > which will be either clear, or shades of yellow right through to black with > floating tar. If yellow, this will indicate the presence of pyrolisis > distillates (read that as tar), and will show up in the flare contributing to > the yellow colour. Black smelly condensate, will show up in the flare as the > stinging radiation that you can test with your hand.
If we ignore our first couple of runs, which were suboptimal on the extreme, our most recent runs have produced surprisingly (to me) limited amounts of liquid, but what was there was indeed "shades of yellow". > Reply. Neither. I am referring to the outlet connection for the gas to the > cyclone. If you are not quenching the gas to below 500C quickly, then you > will make sub-micron soot that will pass straight through the cyclone, and be > carried by the gas humidity to your flare. Oh duh. My bad, I should have understood you, sorry! Yes, we did install a TC in the inlet of the cyclone. And the cyclone is bolted directly to the gasifier shell. Our exit gas at the time of the most recently posted video clip (both the afternoon and night-time runs) was between 225 - 243C (440 - 470F). So per your expectations, we're good there. (Before anyone jumps on that and says that is too cool, please realize that we are pre-heating our incoming air in the space between our firetube and shell.) > I will say though, that you can affect the gas quality changing from suction > to blown. Interesting. I wonder why that would be. > Reply. The flare TC while not accurate, is close enough to indicate the > presence of tar. A reasonably clean gas free of tar should not be hotter than > 1,050C and over that your gas is in tiger country! Am I correct to assume that your specification of 1,050C is with a properly designed flare? (Since I now understand that our flare is most certainly NOT properly designed.) > I think the way your flare is designed is adding to the problem, as the > white core at high velocity can also indicate unmixed gas, which will revert > into soot in the flare itself. Oh now that is just not fair! That would be very bad form if we have a nice gasifier but the FLARE was making the gasifier look bad! <sigh> Well, rebuilding the flare has, thanks to these discussions, become our top priority. > This will of course give you the red tinge. You do need a controlled pressure > air supply into your flare mixing chamber to match the pressured gas coming > out, as just aspirated air will be inadequate. Am I correct to assume that it goes without saying that everything downstream from the compressor's regulator is essentially "open pipe". Obviously even open pipe represents some level of restriction but while we certainly have gas flow, I wouldn't expect the pressure at the flare outlet to be markedly different from ambient. > While I have limited comment to answering your questions regarding the flare > within the experience we have accumulated, it would seem your gasification > parameters may not be providing you with complete tar cracking. Don't panic, > but start by assessing the condensate quality, then change and test only one > thing at a time. Given this is the first gasifier we've ever built, we would have been shocked if everything worked perfect straight away. We expected a learning experience, though we are cautiously pleased with where we are at this early stage. However, this discussion board has been a huge help all along. We've been here for awhile, though have not posted much, and many of the discussions here have been very helpful in our design and assembly efforts. And though I've not heard from Tom Reed in awhile, a huge cyber-bouquet of roses (or maybe a big cyber-bucket of nice dry wood pellets?) to him for the information he has made available through the Biomass Energy Foundation Press. > > Hope this may be of assistance. Thanks much! -brian > > Doug Williams, > Fluidyne. _______________________________________________ Gasification mailing list [email protected] http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org http://gasifiers.bioenergylists.org http://info.bioenergylists.org
