[Gasification] Producer gas injection through spark plug?

[Jonathan Pratt]

To Tom Reed & Others...

In "Solar Hydrogen Civilization" by Roy McAlister a very interesting method 
of supplying hydrogen to the engine was written about.

Essentially he talks about a simple conversion of regular 4 stroke spark 
ignition engine being converted to an engine running on hydrogen by way of a 
simple modified spark plug which also serves as the injector for hydrogen 
gas.  Now a couple things about this are important.

1.  The modification is simple by way of this cheap modified spark plug/gas 
injector
2. The engine is allowed to run on a very lean mix of hydrogen because 
hydrogen is combustable at very low concentrations in air (down to 5%)
    This (lean) fuel mix essentially ups the compression ratio (without 
increasing compression) of a regular gas engine, greatly boosting efficiency 
due to the very lean fuel mix.


Now I realize producer gas (with biomass) only has a 20% or so ratio of 
hydrogen so the advantages of doing the same thing with producer gas won't 
particularly increase the engine efficiency because it cannot be run as lean 
as pure hydrogen.

However it crossed my mind that this method of injection may make the engine 
much more tolerant of tar in the gas.  If the gas injection bypasses the 
valves entirely won't the issue of tar gumming up valves be solved?  And 
what tar is in the gas should be combusted in the engine and not accumulate 
on the inner surfaces within the cylinder.

As so many of the problems of running engines on "woodgas" are caused by 
"tarry" gas won't this solve that problem?

I'm not saying that woodgas should be "tar" rich only that maybe if this 
method of injection is used than not so much an elaborate and expensive 
filtration method are necessary or also that fluctuations in tar levels at 
different engine loads may not be of as much of a concern.

Others please comment or note where tar might still be an issue or cause 
problems if this method of injection is used.  Assuming that the fuel lines 
themselves going to the engine aren't affected.


Jonathan Pratt