[Gasification] CO2 recycling

[Ken Boak]

George, Daniel,

I have been following this thread with some interest.

Putting microwave energy to one side for the moment, is this plasma 
conversion process not what is being used on a much larger scale to convert 
municipal solid waste into syngas, steam and process heat?

It was my understanding that several plasma convertor plants are being 
planned, including one in St. Lucie County Florida.,  with companies such as 
Startech pioneering this work as in a recent Popular Science article.

http://www.popsci.com/popsci/science/873aae7bf86c0110vgnvcm1000004eecbccdrcrd.html


"We'll generate 160 megawatts a day from the garbage," Hillestad says, "but 
we'll consume only 40 megawatts to run the plant. We'll sell the net energy 
to the local power grid." Sales from excess electricity might allow 
Geoplasma to break even in 20 years.

Look at the plasma cell being the "catalyst" (a poor choice of word) which 
allows engine grade gas to be produced from the tarry output of a 
conventional gasifier.
Most of the exothermic heat needed to pyrolise the biomass has been created 
from the oxidation of th charcoal. The plasma cell is not being asked to 
supply the hole energy input, just sufficient to allow high temperature 
ctacking of the tars.

On a more practical note, I have been tinkering in the workshop.

Using some carbon arc welding rods and a stainless steel can containing damp 
barbeque charcoal (not briquettes - not only do these not burn but they 
don't conduct either!) I was able to get some fairly impressive plasma 
reduction of the charcoal using a dc supply of 24 volts and about 30 amps. 
It was so good I rapidly blew holes in the 316 stainless steel kitchen 
container, where a multitude of small arcs established between the charcoal 
where it touched the outer skin of the can..  The anode was the stainless 
can and the cathode was a single rod in the centre of the pile of charcoal 
pieces

With a power input of about 3/4 kilowatt, a small plasma cell  about the 
size of a bean can could be used to clean up the sooty exhaust output  of 
the diesel generator set,  and oxidise the carbon to CO and reduce the steam 
to H2.

The energy input for this comes from the plasma arc and some of the charcoal 
that is oxidised by the plasma in the usual exothermic manner.

In the diesel exhaust there is no shortage of soot and water vapour, and 
there is possibly enough excess air to feed the exothermic reaction. There's 
close to 4kW of heat energy available in my diesel exhaust, which will 
readily char the biomass and get it up toclose to 600C.   The next 
experiment will be to try the experiment in a vessel through which the hot 
engine exhaust passes over the charcoal.




Ken