[Gasification] Characterization of waste water from biomass gasification equipment: A case-study from Cambodia

Pete & Sheri spaco at baldwin-telecom.net
Wed Jan 6 15:41:31 CST 2016

Thank you, Doug.
  Yes, that is useful.
So---- what if one allowed the scrubber water to sit still for a couple of days?  Would most of the "condensable hydrocarbons" and the tar rise to the top?  (I assume that most that "bad stuff" isn't water soluble.)  Then, could that top layer be sucked off, making for a concentrate that might be easier to deal with?  And, would the remaining "water" be useful in the scrubber again?

My reason for asking the original question is this:
  I have been testing a JXQ-10 for several years now.  I can get it to make enough gas to run an Onan 6.5KW genset for up to about 4 hours per batch, at about 3KW net, max..  The thing that always ends the run is when the reactor is full of wood chips to the top.
As I watch maximum  power, and I see it begin to drop, I can add a thin layer of wood chips and, IMMEDIATELY to power comes back up.  It appears to me that it's the new wood chips that are the "new" energy source, not the (rapid change in) dissociation of CO2 to CO and O2 or the sudden "new" dissociation of H2O to H2 and O2. 

Pete Stanaitis

-----Original Message-----
From: Doug Williams [mailto:doug.williams.nz at gmail.com] 
Sent: Wednesday, January 06, 2016 2:46 PM
To: Discussion of biomass pyrolysis and gasification
Cc: Pete & Sheri; gasifiers at bioenergylists.org; biochar at yahoogroups.com
Subject: Re: [Gasification] Characterization of waste water from biomass gasification equipment: A case-study from Cambodia

Hi Pete,
Another way to answer your question:

The none condensible combustible gas of CO and H2 form in the same way by reduction and decomposition of water like you say, even though bed temperatures of these finer packed beds appear lower than conventional wood gasifiers. At the micro level interstitial space between the carbon and siliceous ash, very localized high exothermic temperature exists to make permanent gas (over 850C) but not enough to convert all the hydrocarbons (usually lumped together as C4's) which will condense and are caught in the scrubber water. 

It probably is worth mentioning that one fix doesn't suit all, and any discussion should state specially the fuel type, and or method of gasification, but cleaning tar gas still requires a reasonably affordable resolution. 

Hope this was useful.

Doug Williams.

On Mon, 4 Jan 2016 11:15:42 -0600
"Pete & Sheri" <spaco at baldwin-telecom.net> wrote:

> “Crop residues are best gasified at low temperatures. Low temperatures generate tars”
> Does this mean that  a high percentage of the combustable gas is actually hydrocarbons, etc. released by heating the residue, rather than from the reduction of CO and decomposition of water?
> Pete Stanaitis

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