[Stoves] Reducing smoke with steam

[Philip Lloyd]

My understanding is that it is indeed a chemical reaction.  In the body of
the flare, there is insufficient oxygen to burn residual hydrocarbons and
carbon.  The hydrocarbons and carbon are, however, hot, so the steam reacts
with them according to the usual steam - gasification reactions to make
hydrogen and CO.  In effect, the lack of oxygen is made good by supplying
the oxygen from the steam.  Then, further out in the flame, where there is
an adequate supply of oxygen, the hydrogen and CO burn normally.  

Without the steam, the unburned hydrocarbons and carbon burn slowly once
they reach the oxygen-rich zone at the edge of the flame, and can escape as
particulates ("smoke"). The candle experiment shows this quite nicely.

Regards and seasons greetings!

(Dr)Philip Lloyd
Energy Research Centre
University of Cape Town
Private Bag Rondebosch 7701
South Africa
Tel +27 (0)21 650 3896
Fax +27 (0)21 650 2830

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of John Davies
Sent: 01 January 2008 09:52
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Reducing smoke with steam

Greetings,

I agree with  Peter's thoughts. Those flares work on the same principal of
adding air to the gas before combustion. in the same way that a domestic gas
burner sucks in air and mixes with the gas before the burner.  The steam
jets air into the gas below the flame. What is happening inside the flame
with the steam is anybody's guess.

John Davies.


>I wonder if there is a chemical reaction, perhaps it is purely physical.
> Increasing the volume and thus increasing the surface area of the 
>plume  enabling diffusion of enough air to ensure complete combustion.
> (See Paul, I changed the subject line and lopped the tail)
>
> Peter Verhaart