Greetings all.
I have to agree with Doug's replies to this post, simply from the standpoint of my own findings. "Slipping" a small portion of the spent char (under 2%) through the reduction zone acts as a "conveyor belt" if you will, to move spent ash through a stationary system. I have gasifiers here, that have run hundreds, and hundreds, of continuous hours un-attended, NO shaking, NO vibration, and NO poking or prodding, simply because of the slipping method. It does indeed work, and very well, for stationary downdraft systems. The spent char can be removed from the ash with a simple rotary screen arrangement once out of the gasifier, and used as bio-char for soil enrichenment. (for that matter, so can the ash.) Greg Manning, Canadian Gasifier Ltd. Building Hi-Performance Gasifiers, Since 2001 Brandon, Manitoba, Canada 1 (204) 726-1851 -----Original Message----- From: [email protected] [mailto:[email protected]]on Behalf Of doug.williams Sent: Friday, September 24, 2010 6:45 PM To: Discussion of biomass pyrolysis and gasification Subject: Re: [Gasification] Video of Imbert factory, 1942. And grate shaking Hi Jim and Colleagues, This is certainly a rare glimpse of the past, even if it is glamorised just a tad. http://www.youtube.com/user/bioenergyken >there are some interesting things to see in the video. in particular, >between 2 and 3 minutes, there is a quick shot of how the imbert did >its grate shaking. bear and i are currently rather interested in this >question and doing lots of testing to characterize the impacts of >different shaking mode types and different grate hole sizes. In my visits to Germany where I had a chance to talk to old men users, the shaker was important for start-up to have fresh porous char in the reduction zone, and to refresh this grate char bed support on each refilling. >as we all know, bell packing is a major challenge for long untended >running. needing to poke a rod down the rig every once in awhile is >unacceptable for untended genset operation. expert operators of car >rigs tend to do this regularly, and don't think much of it. for a >newbie or a regular run situation, you need to eliminate the knowledge >dependency that only the expert has so they know when and why to do >this. The Imbert design, and any other that draws the gas up around the sides, is prone to plugging in the central core, and channelling down the sides of the reduction zone bed as the gas takes the shortest route out towards the source of suction. A pyramid of solidified char and fines form on the grate quickly after start-up, then all the gas forces it's way out down the sides often resulting in channels. >the imbert apparently had the side shake design via a pivot point >going through a gimble ball. this is a mode i was playing with in the >phillipines given challenging fuel there. now we're trying to >formalize the performance of this vs vibrator, vs in/out shake vs >rotary. oddly, we're finding up and down motion to potentially be more >effective than side to side or rotary motion. i thought such would >contribute to packing above. but so far it seems to do the opposite. The up and down shake we have used since 1977, but the issue of any shaking is that it disturbs the char evolution right through the bed from top to bottom. Any shake should only be used to clear a stray stone or clinker, as actual bed disturbance can results in a total loss of CO2 reduction., and of course a slug of tar coming through. Engine vibration is good, but can cause packing of the bed, if the motion is vertical rather than horizontal. Our experience has shown over many trials of fuels, that shaking is not going to give you a good quality gas with any high ash fuel that needs shaking to keep the gas flowing. Hope this is of some assistance, Doug Williams, Fluidyne Gasification. _______________________________________________ Gasification mailing list [email protected] http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org http://gasifiers.bioenergylists.org http://info.bioenergylists.org UNSUBSCRIBE HERE; http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.856 / Virus Database: 271.1.1/3156 - Release Date: 09/24/10 12:16:00 _______________________________________________ Gasification mailing list [email protected] http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org http://gasifiers.bioenergylists.org http://info.bioenergylists.org UNSUBSCRIBE HERE; http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
