Uuummmm!! Some times you get into a discussion and a little voice in your head says, “just shut up and listen because others know much better than you (me)”". The little voice has spoken but I don’t know enough to listen
Yep Kristijan, your nozzles did follow the Imbert dimensions and your ring of fire was just auxiliary air to burn tar that may have escaped between the nozzles. ( that is my interpretation of what happened) Drue, with no nozzles is working more like a WK design. He really doesn’t design for a particularly high velocity air coming out of the nozzles. There fore he isn’t looking to penetrate the charcoal column to or near to the center. It just comes out of the nozzle and bends down and in the long distance to the restriction it works its way through the entire column which as it goes down is diminishing in diameter as it approaches the restriction. Drue’s ring of fire does like Mr. Wayne’s, it penetrates the column but mostly, bends, blends in and oxidizes on its way down.
Yes Drue has made a modified FEMA. And yes adding the ring of fire has “fixed” the oxidation zone. I believe the moving oxidation zone was the reason for tar not burning in the FEMA.
I am all for a “restriction” but first lets see if this will work HIS way with out it. I’ve said it three times already, but one more time, Drue is confusing himself/and us, by NOT knowing how hard he is pulling on the gasifier with the shop vac. My impression he is pulling very hard ( or as we say “overpulling”) Overpull will burn tars. He has a valve to cut down the amount of vacuum. I am not sure he IS cutting the vacuum pulling on the grate/reduction zone/ring of fire. Maybe my thinking is incorrect but; If you have 2 pieces of 4in dia pipe connected by a piece of 1in dia pipe and you pull 50 in. H2O on the end of one 4 in. pipe, you will NOT get 50 in. H2O at the other end of the other 4 in dia pipe ( if the other end is open. if closed another story). I believe that is what he is doing with the ball valve he thinks is restricting his vacuum. He could have 50 in. H20 at the shop vac. Then it goes into a 1 in dia pipe and then back out to about a 2 in. dia pipe. ( 2in.- 1in.- 2in.) At the end of the second 2 in. pipe he will NOT get 50 in of vacuum but may 30 or 40in. H20. That would still be over pulling his gasifier, thus getting a blue tar free flame. For a good running gasifier I believe we need to run at 10 to 15 in. H2O vacuum. To get that in the 2in. pipe at the gasifier, the ball valve would have to drop the vacuum in the 1 in. pipe to about 20 to 25 in. H20.
All of these figures are just stuff off the top of my head but the point I am trying to make is, when he turned the ball valve towards OFF I did not see the flame diminish, did you?
I did see him run the snow blower, which in my thinking is WAY underpulling his gasifier and yet he didn’t gum the valves up. So as of yet, I don’t think we can say his design is a failure or needs modification. I don’t know how he is getting away with out a restriction but heck, one guy on here stopped putting a GRATE in his design-- I have a problem understand how he is getting away with that. TomC