[Gasification] tests to design a new cheap gasifier fan

sabbadess at aol.com sabbadess at aol.com
Sun Oct 3 05:58:30 CDT 2010


Stay away from Tesla turbines.  I've already played with them and they are a pain.  I ended up laser cutting my disks then using #4 flat washers as spacers to get the roughly .015 spacing between plates.  The problem was dealing with the lack of flatness in the sheet stock.  Granted I was using it as a power turbine, but it was still painful.

Given how close the disks need to be I wouldn't go there.  Any little bit of tars or ash and they will plug.  I would stay on your present course.

-----Original Message-----
From: jim mason <jim at allpowerlabs.org>
To: Discussion of biomass pyrolysis and gasification <gasification at lists.bioenergylists.org>
Sent: Sun, Oct 3, 2010 6:33 am
Subject: Re: [Gasification] tests to design a new cheap gasifier fan

the rotor made from the spinning disk with vanes between we have not
et tested.  we should i agree.  we have testing the one sided version
ith vanes at various angles forward and back from perpendicular.  i
as surprised to find it makes little difference.  backward rake,
speically curve backwards at the tip is done with pro fans to reduce
oise, not increase pressure/vac.  it actually reduces performance a
it has taken awhile to get through my head that these fans are working
s centrifugal devices, not pressure devices.  the blades are not
evers or pumps.  they are simple accelerators for air mass.   your
ressure/vac is coming from velocity and inertia/momentum.
this is why the tightness to the walls makes little difference.  i've
oved the rotor / wall tolerance around quite a bit and saw very
ittle diffference.  i've read this is also why you see less double
alled rotors that one might expect.  but i've yet to test this so
an't really say.  greg says he gets 25% more out of these types.
some devices in the weed blower vac world put vanes on both sides of
eh disk.  but i think this is to prevent the weeds from getting stuck
n the back of the disk.  see the toro blower for example of this.
arnt raises an interesting concern about the rotor bending.  the other
ay to deal with this would be to make a full slot for the vanes, and
ush the vanes through so they stick out on both sides.  put a hole in
he center so air can feed to both sides of the rotor.
and . . . i have to suggest it. . .
this might finally be a reasonable application for a tesla turbine.
any parallel disks, no vanes or welding.  problem is the distance
etween the disks needs to be related to the laminar layer thickness
t the rpms one is running.  the distances are usually very small.
ike a few 100ths of an inch.  these are difficult tolerances to
aintain with junk cut metal.
however, it begs to be tried.  we will soon here.  maybe at the
orkshop next weekend.

On Sat, Oct 2, 2010 at 7:39 PM, Greg Manning <a31ford at gmail.com> wrote:

  Greetings Jim, and list members.

  Jim, if you want a better fan, (and cheaper), simply make 2 disks (one
 mounts on the shaft, the other has the larger hole for the inlet.)

  then use strips of heavy tin (or light gauge metal) and form them into a Z
 shape (well, an L with a dog leg the other end, and the opposite way,
 somewhat like a "90 degree Z")

  take these and pop rivet with STEEL rivets (NOT aluminum ones) so they are
 sandwiched between the two disks in a radial fashion (like your welded
 version on your site, BUT with the extra disk on the inlet side of things.

  the extra disk should run as close as it can to the outer housing the
 Bernoulli principal will help stabilize the outer disk, and the outer disk
 will add about 25% more suction to the unit for the same RPM (therefore the
 entire unit could be built smaller and lighter).

 Greg Manning,
 Canadian Gasifier Ltd.
 Building Hi-Performance Gasifiers, Since 2001

 Brandon, Manitoba, Canada
 1 (204) 726-1851

 -----Original Message-----
 From: gasification-bounces at lists.bioenergylists.org
 [mailto:gasification-bounces at lists.bioenergylists.org]On Behalf Of jim
 Sent: Saturday, October 02, 2010 4:58 PM
 To: gasification at bioenergylists.org
 Subject: [Gasification] tests to design a new cheap gasifier fan

 we've been doing some work lately to design a new fan/blower that will
 produce the needed vac and heat tolerance for gasifier operation.  as
 we all know, there is not an inexpensive source for such a thing from
 other industries and applications.  thus we had to build one for the
 early gek kits.

 the original gek fan proved to not be strong enough once we finally
 characterized the vac numbers that produce the flow/heat rates that
 correspond to full tar conversion.  the ejector/venturi solution we're
 using currently produces plenty of vac and is very flexible, but
 requires compressed air.  this is not good for many off grid
 situations.  thus we still need a good fan/blower source.  and one
 that works on 12vdc, not an ac source.

 here's the info an pictures of our recent tests to produce this.  we
 are working towards a much simplified solution that also gets rid of
 the welding to make it.  this is based on the common car/truck fasco
 type fan motor.



 Jim Mason
 Website: http://www.whatiamupto.com
 Current Projects:
    - Gasifier Experimenters Kit (the GEK): http://www.gekgasifier.com
    - Escape from Berkeley alt fuels vehicle race: www.escapefromberkeley.com
    - ALL Power Labs on Twitter: http://twitter.com/allpowerlabs
    - Shipyard Announce list:

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ebsite: http://www.whatiamupto.com
urrent Projects:
  - Gasifier Experimenters Kit (the GEK): http://www.gekgasifier.com
  - Escape from Berkeley alt fuels vehicle race: www.escapefromberkeley.com
  - ALL Power Labs on Twitter: http://twitter.com/allpowerlabs
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