[Gasification] Why would you want to make heating grade woodgas?

[Peter & Kerry]

Hi David,

Our experience is that energy conversion efficiency is often secondary, 
or not even relevant at all due to other factors.

We are working with clients whose biomass is high in potassium and can't 
be combusted cleanly in their boilers without creating excessive boiler 
maintenance due to the deposits building up on the boiler heat exchange 
surfaces. Gasifying this material then combustion of the clean gas can 
solve this problem for them whilst giving much easier process control 
and a higher value ash/char they can recycle through their compost and 
farming operation.

We have others where contamination (pesticide/herbicide residues, 
plastics etc) in their waste materials require high temperature 
incineration for safe energy recovery and use (in essence not 
practical). Again the gasifier not only addresses this issue but allows 
conversion of a problematic organic waste to an easy to use gas for 
their process heat needs and allowing straightforward co-firing with 
their "business as usual" use of LPG burners for the same job. In fact 
the highest economic return for the gasifier is in displacing the LPG 
use (compared to say electricity generation, which in one particular 
situation even runs third behind avoided cost of existing waste storage 
and disposal)

Due to the large number of requests we have bit the bullet and built a 
small scale round hearth system for individual users (from a design 
kicking around in our heads for a while now) to complement our linear 
hearth design which is better suited to much larger commercial 
applications. The first prototype is undergoing commissioning trials at 
the moment and is so far working very well, even using very ordinary 
chip (looking more like coarse woody gravel with lots of fines!) 
produced using a cheap Chinese PTO disc chipper. Well enough in fact 
that we are now fitting automatic feeding and ash removal to allow 
continuous run (multi day) trials.

We know where the ultimate configuration of such a system can end up 
when you get it right, and is far superior in both fuel flexibility and 
ease of use than any straight combustion furnace no matter the design, 
even if you only use the gas for home heating and hot water.

As one poster to the list recently put succinctly "Fuel prep sucks!" and 
in our view one of the biggest drawbacks for most conventional gasifier 
designs that get talked about, along with most boiler designs that 
likewise have very fussy fuel specs for effective use.

Cheers,
Peter
Real Power Systems Pty Ltd


On 14/04/2012 5:00 AM, gasification-request at lists.bioenergylists.org wrote:
> Why would you want to make heating grade woodgas?