It all started on 15 mai 2013, with a discusion on the famous German "Holz gibt Gas" about grate design and how to overcome the problem of the grate of a gasifier getting blocked by packed charcoal dust, dirt and other elements that prevent a gasifier from breathing normaly.
I posted then following drawing of an concept. which had in embrio the most important element of V3
An other member of the "HgG" forum, Bulldoc actualy had build a such a grate system but, at least to my knowledge never tested it in practise.
Looking however allways to eliminate elements and in constant fear for overengeneering, we tried first a grateless design that would had no mechanical turning pats and that would work purely on suction. First came this;
....But because of too much resistance it soon was changed in this design.
Merely just one elbow and a reduction element that widened at exit. The so called stone slide. The Gasifier drum was half filled with fresh charcoal in wich the DriZzler tube was imersed. Further a level sensor and also inside the bucket was the cyclone. This design relied solemly on replenishment of the original charcoal by new gassed out coaled large woodchips. If too much charcoal would enter then the level sensor would trigger a mechanism to evacuate the exces coal out of the Drum.
It was thought that the finest charcoal dust would go in suspension with the gasstream and the heavier elements such as stones and nails would sunc to the bottem wher they landed in a dirt-pit.
The gasifier was put on a maraton test to see if the idea would work. The suspension of the fine dust worked well but to our great surprice the available charcoal could not been kept on level. More was consumed than could be produced, After 24 hours the charcoal was all gone and the gasifier went out.
A video of this test was made and published on youtube.
Conclusion was made quick. We must find a way to hold the charcoal in a steady way. An in between idea, a turning grate was never tested.
In the mean time spacepater, an active member of our DriZzleR Forum also started experiments wit grateless design bringing into my mind back the old year 2013 idea and a new improved gasifier with a very condensed feeding mechanism (not a auger more a vice because of the flights beeing very close to each other) was build.
A test turned out not very succesfull. The vice had much play inside the reduction tube and the pull by the blower sucked the vice empty soon. A new one whit a vice closer matching the reduction tube and with a large dropbox-gasexpansion tower was preforming very well. It had a so called stone transporter The vice and a charcoal holder.
Stones went in the dirt-pit, charcoal in a charcoal container where eventualy by suficient amout it could be lighted and renter the gasstream untill copletely consumed. This coproduction woodgas and charcoalgas machine was not tested in this form. We only tested the woodgas version,
The dirt pit however was very small and did not allowed longer runs than 4 hours before it had to be emptied.
Drawing of the improved on with return charcoal transport and charcoal holder/afterburner. Was tested only in woodgas version.
Being pleased with the results finaly version 3 came to be tested and was merely build around the same princeipe of the V2 but designed for longer runs. It is the latter that can be seen in this video.
This text is written on demand of many people to asked about how the interior of the Grateless looked like. As we never want to show untested and unfunctional devices it took a little while before we could forfill the demand. This V3 is performing good enough to show. However we discoverd some things that can be improved and that is what we are going to do. So saty tuned the V3 is not the last grateless we will build.
Luk
Pascal
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