[Gasification] CO2 recycling

[doug.williams]

Hi Harry, and Colleagues,

You have read:

> Interesting that hydrogen is raised as useful in IC's for its high flame 
> speed.  i have found that the GE Jenbacher folks hate it as it reduces the 
> Methane nuber so much that it >makes knocking a super pain in the engine.

Jenbacher engines have an interesting history of being used for gasified 
projects that had dirty producer gas as fuel. This suggests that CH4 was the 
culprit, rather than H2.

> There is a greater value in the Kalle use of the Monotrator for improving 
> the exploitation of the pyrolysis gases in the combustion zone by letting 
> the condensate return to the >combustion zone outside of the reacting bed.

This is a conflict of systems. Kalle was a charcoal gasifier and had no 
condensate, or pyrolisis gases, unlike a wood system, and did not 
incorporate the Monerator hopper design.


> This helps avoid making them refractory as they travel downwards in a 
> downdraft bed.

As a charcoal gasifier, Kalle used the insulating effects that charcoal 
provides to make a lighter gasifier for mobile application.

>Of course Kalle et al used eductors, the monorator, etc quite effectively 
>in this manner.

Only to re-circulate CO2 from the engine exhaust using educators, or a 
suction device.

> Better overall carbon conversion is the ultimat goal of downdraft 
> gasification and the sneaking by of these volatiles helps present them to 
> the combuastion zone in a >more .easily converted form.

Downdraft gasifiers are not automatically tar cracking gasifiers. The 
oxidation zone, or combustion zone as you call it, only burns the gaseous 
component of stack gases, or pyrolysis gases, or distillation gases, 
depending on which term you use.  The heavier hydrocarbons (tar) are 
thermally cracked at the high temperature throat, which scavenges the 
unburnt heavier hydrocarbons from UNDER the combustion, or oxidation zone. 
Correctly designed gasifiers create CO2 and exothermic heat, which then 
consumes the carbon and heat in the endothermic reaction of reduction to CO. 
Certainly it consumes carbon, the real name of the game of gasification.

>Slower pyrolysis has shown to produce a gas rich in benzene as well so 
>hence the separation of an updraft due to evaporation of bouyant gases 
>below the top of the fuel bed in a slower manner produces a nice gasoline 
>like product for combustion in an IC engine.

Sorry to tell you that this is rubbish in  terms of gas suitable for 
engines. The presence of benzene represents the presence of condensable tars 
in the gas. Benzene is a distillation zone gas that will be cracked in the 
throat high temperature, and if it survives that, it is indication of 
inadequate throat cracking temperature. Alternately, the gas must be 
scrubbed or cleaned, and that raises some interesting questions of the 
system used.

> The GEM folks have been using their pyrolyzers quite effectively in this 
> application.

I am not familiar with who GEM are, or their history, so can you please 
refer me to their claims of commercial success.

> Carbon conversion suffers however.

So GEM do not maximize the conversion of carbon, but clean the pyrolisis gas 
which includes benzene to run an engine, producing a surplus of charcoal?

> And so the old 'tried and true' basic thermodynamic laws and principles 
> you mention are still valuable in this brave new world of 'dilithium 
> crystals' and 'warp drives'.

I would agree with you on this one, but it depends on your basic 
understanding of the principles of gasification phenomena, not so much the 
thermodynamics. I would rather see dimensional drawings to prove an 
improvement  to existing technology, than a description imploring innovators 
or investors, to pick up the idea and develop it. We all have plenty of 
ideas, but more often than not, they just do not stand up to close scrutiny, 
or only work as a curiosity in a lab situation.

Regards,
Doug Williams,
Fluidyne.