[Stoves] Airflow For Biomass Fired Appliances- Natural DraftStoves

[Lanny Henson]

Dean,

I have started a list starting using your principals to which I may add thoughts, and ideas from the list.

I have already tinkered with your title, how about?

"Biomass fired appliance design principles"

I used "appliances" instead of stove so it will include ovens.



I will post the list, to the stove list, under a separate topic, after there is a title.

I have put it on the back burner to simmer if you think of anything else.

You may have to show me how to give credits.

Lanny

  ----- Original Message ----- 
  From: Dean Still 
  To: Discussion of biomass cooking stoves 
  Sent: Sunday, April 14, 2013 2:53 PM
  Subject: Re: [Stoves] Airflow For Biomass Fired Appliances- Natural DraftStoves


  Dear Lanny,


  Hope you get better soon!


  Here are the design principles I use to tune a stove (same for Rocket, TLUD, Fan stoves).


  I imagine that to get clean combustion all of the gases and smoke are forced to enter the flame.


  Then the gases and smoke stay in the flame long enough to be burned up.


  The very hot yellow/white flames easily make black carbon.


  The less hot deeper yellow/red flames make less/no black carbon.


  Draft is decreased or increased until the right amount of gas and smoke is delivered to the flame for the right amount of time.


  Draft has a lot to do with the correct metering of fuel (gas and smoke) into the flame: how fast gas and smoke is made and how much flame is made. I think we want lots of flame but only the right metered amount of gas and flame to enter the flame. 


  Lengthening the time for combustion in the flame is good when: the metering of fuel stays right,  the air/fuel ratio stays right, and losses through the stove body do not increase too much (good insulation.)


  Flame is needed to combust smoke and gas.


  Something like that.


  Best,


  Dean





  On Sun, Apr 14, 2013 at 11:25 AM, Alex English <english at kingston.net> wrote:

    Lanny,
    I understand the comment below but I think flame height can be shortened with excessive excess air. The lowest emissions CO/CO2 and highest temperatures, at some power levels, in appliances that I have tested has often been when there is a significantly taller tail of flame. 

    However, don't believe  all tall tails :)
    Alex

    On 14/04/2013 1:51 PM, Lanny Henson wrote:



    The combustion air needs to be focused on the combustion zone in a way that shortens the flame height. More like the way a TLUD with a fan works. 

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