[Gasification] updraft and stratified downdraft sizing questions

[gasman]

Hello Jim!



the BEF books have lots of info on sizing traditional downdraft gasifiers of the imbert type design.  but i can't find any info on sizing and gas rate ranges on updrafts or stratified downdrafts.



¤¤¤For downdraft, a minimum IV of 0,5 m/s. (downdraft) ¤¤¤


i can elaborate from gas rates for x throat diameter in an imbert, and equate throat in an imbert to vessel size of updraft / stratified downdraft. imbert gas rates are between .3 and .9 cubic meters/h for each square centimeter of throat (normallized to atmospheric temp and pressure).  

 

¤¤¤ Old time norms = 0 degrees Celsius! Not 25! ¤¤¤

 

but that is also with constricted air, not air fully open
from the top or bottom.

 

¤¤¤ Blasting is NOT = Restricting! The intake is still 

~ 60% of the 0-cooled output volume! The chemical process gets what it asks for! 

¤¤¤


in an imbert, the ratio of total cross sectional area in the tuyeres for air inlet to the cross sectional area of the throat is around .004:1 to .008:1.  in an updraft or a stratified downdraft, it is 1:1.

 

¤¤¤ Here the decimals run wild ;-)

4 to 8 %, not promille! Some Imberts use even 3,5 %. ¤¤¤

 

quite a difference. so just equating gas rates between throat area and vessel size in updraft/downdraft seems not a good approximation.

i'm curious to know how my gas pull rate on the updraft rig i built last week falls within desired ranges.  and i'm equally curious to know how to size the stratified downdraft i'm working on next.

any rules of thumb out there?

j

 

¤¤¤ Yes, as long as going downdraft: 

Probably your book gives for the "simplified & stratified" downdraft a minimum of 0,5 m/s, as an imaginary velocity. (cool & empty)

 

For other downdrafts:

 

This book gives imaginary velocities for "Throatless", "One-throat", and "double-throat" gasifiers, as well as transformation between gas flow and fuel flow!

 

http://www.fao.org/docrep/t0512e/t0512e00.htm 

 

However, as it deals with quality gas production, it does not deal with dirty gas production ;-))

¤¤¤

 

I can perhaps come up with updraft velocities, if necessary...

 

Max

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