Nozzle angle introduction

General Discussion
#1

I have been slowly putting together plans for my gasifier as I come across new inspiration and information. The latest technical issue facing me is the angle of air nozzle introduction. Most imbert gasifier designs Ive come across have the nozzles facing eachother, perpendicular to the shell of the furnace. Recently I have seen a gasifier with the nozzles pointed at a downward angle. Is there any advantage to this in a wood chunk gasifer? Or does it only offer improvement in exotically fuelled gasifers like wood chip or various crop residues? Is it any more or less sutiable for varying load applications like those faced in automobiles?

My educated guess on this is that as long as you have the rest of your dimensions correct, The major influence of a downward facing nozzle is a different profile combustion zone that optimally eliminates bridging. Not That thats a problem anyhow in most wood chunk fuelled gasifers

If your a memberof the yahoo woodgas group you can see what got me thinking about this here:
http://tech.dir.groups.yahoo.com/group/WoodGas/message/43620

http://f1.grp.yahoofs.com/v1/QJmLT497UafIO8TsVDbfP_jN1ddTt2oUPeae6Bpg0Rq4oxa8fsHZqCs9cLrdxF3joJD363z4XQNzphetmfgUVL8ws7gvpeAaHQ/Sabbadess/How%20to%20build%20a%20gasifier.pdf

On pg. 15 of the file he argues that bell shaped restrictions create unecessary temperatures, and that using his design you can run a much more efficient internal temperature. Which would be great as long as you were not generating any tar past the reduction zone. Im curious if anyone here as any experience relating to this?

#2

You also want a hot zone above of the nozzles for pyrolising/charring. Pointing the nozzles downward brings this charring zone also down. And the risk of a raw fuel funnel between the nozzles, because a downward sloped air stream could not reach the centre. Pointing them upward could be beneficial, but extends the oxidation zone, so the nozzle position should be lower than usual. It can melt your nozzles. I would not do take any risk on a first gasifier. Do not fall in the trap of own improvements when you are a layman. You have no reference material.

Regards,
DJ

1 Like
#3

Understood. Thank you for the direction.

#4

I haven’t seen any problems with downward pointing nozzles on a Stephen’s victoria style gasifier… I get lots of charring well about the nozzles but i am running chips for the most part.