[Gasification] Charcoal Gasification No 4.

[doug.williams]

Hi Paul and Colleagues,

Paul offers this method of lighting the gasifier:

> I have seen a large gasifier ignited in South Africa by Gus Johansson 
> using a
> "sparkler" (the kind of long-thin fireworks on a metal wire used at some
> celebrations like the USA 4th of July).  It has its own chemicals that 
> release
> the needed oxygen, so it can burn even without air flow.

These flare type igniters have been used since the 1970's to my knowledge, 
but they are illegal in some parts of the World. In New Zealand, we cannot 
even use emergency road flares.


>The System Johansson gasifiers are downdraft, but I am sure
> the same
> method could ignite an updraft gasifier.

It would be an unnecessary waste of money to use flares to ignite a charcoal 
gasifier, as the charcoal lights instantly once the flame touches the char. 
SJG gasifiers are wood fuelled, and much larger than the single nozzle 
charcoal gasifiers of this discussion.

> Also, you can have a similar type side hole and inject (squirt
> forcefully) some
> ignitor fluid into the char.  Then via the same hole put in a flame to
> ignite. What is then needed is only air movement, either by push
> (pressure) or pull
> (suction).

The same applies to this suggestion, because there is no need to add 
accelerant to charcoal, as only air and flame are required. Having done all 
of this myself, and learnt by bad experiences, stick to simple ignition 
practices, and do not forget that while a flame will suck in, it will also 
blast out under pressure. The point of ignition in a charcoal gasifier is at 
the tip of the air nozzle, and the same applies with wood gasifiers, because 
there should only be charcoal at the level of any air nozzles. So, we use 
one of the air nozzles to ignite, and extra ports  are unnecessary.

> Doug used the word "easily", so he is aware of alternatives and has his
> preferences.  But easily is a relative word, and my experience is that
> positive
> pressure also works "easily."

We start our Mega Class (2MWE) gasifiers under positive pressure, but with 
great care. This was only done originally because we did not have any gas 
cooling on the system, and we needed to learn how the gas making performed, 
and to what output the parameters could be pushed. The Mk3 Mega Class 
(4-600kWe) is all suction, including ignition, so it depends on the "state 
of your equipment" as to how you achieve ignition. The Atlantic Class (100 
kWe) we have in Northern Ireland has electrical hot probe ignition under 
pressure, so there are lots of ways to add cost and complication to 
ignition.

Remember this discussion is for beginners in the main, and there is a need 
to play in the most simple fashion to gain experience, then progress to the 
next stage of cooling and cleaning the gas for an engine application if 
required. However you choose to do this, play SAFETY FIRST in every 
instance, and make it enjoyable without pain (:-)

Doug Williams,
Fluidyne Gasification.