[Stoves] TLUD pellets stove with a venturi burner.

kgharris kgharris at sonic.net
Wed Oct 7 17:09:27 CDT 2015


Roberto,

Nice.  I would like to see test results for particulates.  It should be very clean.  It looks like it is loosely based on Crispins flame tube design with holes added in the tube where the Venturi low pressure area is.  The holes are at the bottom of the burner, so there is better draft and a good burning area above.  If I understand correctly Crispin is using the tube differently, to concentrate the heat and increase the dwell time for the flame in that hot environment.  His secondary air is all added before the flame tube.  Your design looks more compact and perhaps would be a better choice for a TLUD.  

There is a limit to how much gas the burner can handle.  When the foil is removed and more primary air is added the burner is overloaded with gas and a tall diffusion flame forms.  I have been trying to handle this problem by adding more mixing capability, and have had some improvment, but further work is needed.  The problem with the mixing tubes I am using is that along the edges of the combustor, the air exiting the tubes exits at an angle instead of straight out.  This holds the gasses below the burner along the edges, and adds to blowing them to the center, overloading the center of the mixer and wasting air at the edges of the combustor.  This would not be a problem with your design.  You might be able to use two or three of theses mixers side by side to gain a clean higher fire power.  

The concentrator ring is intended to mix the wood gas and air, and the Venturi mixer is intended to mix the wood gas and the air, so you have a duplicate mixing system.  I am not saying good or bad, just something I notice.  

I see Julian has expressed some doubts about the Venturi concept.  Good for him.  I would be very happy if someone with adiquate equipment and technical ability proved or disproved the TLUD Venturi concept, either way.  I perhaps will have to bite the bullet and buy a manometer with the ability to measure down to .001 inch of water column.  My rather primative home made manometer did show a slight pressure drop at the mixer, but not enough to get any measurments.  Our local college science department didn't seem to be interested.

Attached are some photos of the primary control valve I am currently using very successfully.  It looks like something similar might work for you.

Good work Roberto, 

Kirk
  ----- Original Message ----- 
  From: Roberto Poehlmann 
  To: stoves at lists.bioenergylists.org 
  Sent: Tuesday, October 06, 2015 5:53 PM
  Subject: [Stoves] TLUD pellets stove with a venturi burner.


  Hi,


  This is a video of one of my prototypes of a TLUD pellet stove.


  The difference with a "normal" TLUD burner, is that it has a 3 inch tube with secondary air holes after the concentrator ring.

  On top of the the tube, i put a cone to expand the path of the gases, to shorten the flame, and to have a little internal chimney for draft.


  One advantage of this burner, is that you can also burn all of the charcoal made at the pyrolysis stage, with a nice secondary blue flame (if you wish) .


  https://youtu.be/uXMeGcZEYX0



  Greetings
  Roberto Poehlmann
  Valdivia, Chile.


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