Re: Wonderful Fans/extra water

[AJH <andrew.heggie@dtn.ntl.com>]

On Tue, 4 Jun 2002 08:11:12 -0500, Harmon Seaver
<hseaver@cybershamanix.com> wrote:

>On Tue, Jun 04, 2002 at 12:12:17PM +0100, AJH wrote:
>
>> melt. An axial steam turbine coupled to a centrifugal fan could well
>> work and be formed from tincanium, bearings would be a problem. There
>> would be no need for a common shaft as such as they could be formed on
>> the same "propeller", like the bypass fan on a jet.
>> 
>   If a simple (cheap) bearing solution could be found, 

I have considered this, it seems within the realms of possibility for
the axial bearing to be using the steam to float on. Consider the
steam entering the bearing and venting at one end, the other being
blocked. The steam nozzle could then be a continuous slit which also
took up the thrust in the bearing, once rotating wear should be
minimal as it floats on the steam.

OTOH The fans should have little axial load so a bronze bush may last
for years.

>I think this is by far
>the most excellent idea yet put forth. Think of the fans at the bottom of the
>stove with the flash steam tube in the upper secondary burn area -- designed
>right it would also avail a control via the amount of water put in, i.e., the
>stove would self-reduce to a simmer when the water ran out. Or a dab more water
>added later to burn up the charcoal. 

This could also be controlled by the relationship between the monotube
outlet jet size and the reservoir pressure.

>   Perhaps even better, wouldn't the steam from the fans come up into the coals
>and break down, adding H to the woodgas, as is done with bigger gasifiers? Or
>would it dampen the fuel too much?

I have often mentioned this, the thing is the temperature in the co
generator phase of the gasifier is very high. In some car units like
the kalle exhaust gas was recirculated to keep this temperature down.
The thing is, as you note, adding steam to the producer gas reaction
to enable a bit of water gas reaction is highly endothermic AND
requires the temperature in the bed to stay above 700C (or maybe
higher). I think the ejector design will run on only 2% steam by
volume, so it should cause no problem.

I still prefer the aspirator if it can be configured properly, after
having made a few tests it looks like I need less coils than I
currently use.

Now this problem of steam getting into the combustion air need not be
a problem with the close coupled steam turbine and fan as the steam
can vent elsewhere. This is true also if they are made from a piece of
tincanium. The paddle of the centrifugal part is made by cutting them
from a flat sheet as petals on a flower. These being twisted at the
"spoke" that attaches them to the centre through 90 degrees. The steam
jet then playing on the twisted spokes (which become the axial
turbine) and passing straight out the other side, the air inlet for
the centrifugal part running coaxially and with the steam flow, the
outlet being on the perimeter.

I shall see if I can make one if I have a little time.

AJH



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