[Gasification] 500 kW Gasifier concept

Fri Feb 5 04:56:52 CST 2016

On Fri, 5 Feb 2016 01:22:43 +0000, James wrote in message 
<381a44e6a6bc4704821276d0e38335af at PEN-MBX-01.exchangeserver.net.au>:

> Hi Arnt. I have scratched the original concept completely. Your
> recommendation of the Kalle style seems to be the best approach that
> I can find for our fuel... and I certainly don't want to reinvent the
> wheel any more than we have to (already did that when we did the
> BIGCHAR gasifiers). 
> 
> We don't need to closely follow an engine load, so I think we will
> use a VSD controlled air blower to regulate the output, rather than
> the sliding outer tube. Haven't worked out how the ash gets out of a
> continuously fuelled Kalle style unit yet ... perhaps it all ends up
> in the gas ? 

..if you follow Källes recipe, with outer sliding tube and
"wind sieve" etc, you should solve _all_ these problems. ;o)

..my understanding is Källe caught all his ash in filter bags, 
after recycling all his charcoal dust back inside his combustion 
bulb a few times.  
The Källe is selfregulating if you draw gas from it with e.g. 
a fan or an engine and recycle ~1/6 of the exhaust gas back 
in thru the "wind sieve."

..on dry fuel, the Källe was started in half a minute dropping 
in some burning paper down the air tube.  With damp fuel, it 
probably takes a little more light-up fuel to get the fire going, 
you may try dunk your paper in gasoline or add a wee shot of 
oxygen from a welding bottle to get the fire going.

> To answer your other questions:
> 
> The charcoal is relatively fine granular char from our BIGCHAR units
> located on the same site. Nominally 3mm but it does contain 25% fines
> (ie. below 1mm). So not the usual lump charcoal. It is low ash. 

..ah, _perfect_ for a Källe. :o)

> The volatile matter is 10-15%, so pretty low but not zero.

..tars?  The Källe cannot burn tarry fuel, you'll ned my tar vapor
flare for that.

> With the
> benefit of extra thought, this char would be unsuitable for most
> moving bed gasifiers to due to the flow resistance. The Kalle design
> is good in that the gases have to move a short distance between the
> oxidation zone, reduction zone and gas off-take. Moving this fine
> grain charcoal in and out of the reaction zones is likely to be the
> greatest challenge.

..the Källe draws ash and charcoal dust away with the gas flow.
The trick with the "wind sieve" is use (pulsed) exhaust gas to 
blow the dust back inside the the combustion bulb, where the 
charcoal dust fines are burned off and where the ash dust is 
drawn away again.

> 10S is just schedule 10 pipe, i.e. light gauge 304SS pipe. It did not
> expect the outlet pipe to suffer much corrosion, because it is short
> run to a burner head and air cooled .. 

..use mild etc steels everywhere you pipe hot dusty oxygen free gas. 
_Much_ cheaper in the long term. ;o) 

..that nice shiny fancy expensive stuff needs its oxide surface layer 
kept in place to resist ash dust particle erosion.

> If necessary I will line it
> with our high temperature alloy (a non-nickel based alloy which has
> proven resilience in reducing conditions at temperatures to 1000 deg
> C). 

..eh?  Also when carrying dust?  Link?

> I was planning on using a metal/ceramic material tube for the nozzle.
> That material is well proven for temperatures up to 1400 deg C in
> reducing conditions. Not cheap but we don't need much of it.

..just keep in mind where you have oxygen handy, e.g. "inside 
the nozzle" and where you don't, e.g. "outside the nozzle."

> We are planning to do the first one as a nominal 250 kWth size
> now ... so our mistakes are a little smaller.

..if you first do a ~50 - 100kWth, you can build right away upon 
well known WWII Källe territory right off his WWII drawings.

> Regards,
> 
> James
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Wed, 3 Feb 2016 20:02:57 +0100
> From: Arnt Karlsen <arnt at iaksess.no>
> To: gasification at lists.bioenergylists.org
> Subject: Re: [Gasification] 500 kW Gasifier concept
> Message-ID: <20160203200257.7bb73b86 at nb6.lan>
> Content-Type: text/plain; charset=UTF-8
> 
> On Sun, 31 Jan 2016 21:48:12 +0000, James wrote in message
> <96fa96f60a134996b696513ae114466d at PEN-MBX-01.exchangeserver.net.au>:
> 
> > Hello list. I have been asked to design a 500 kW heat gasifier, for 
> > operation on damp nut shell charcoal.
> 
> ..made how?
> 
> > They are using the heat from
> > the producer gas burner to heat water, so I have the luxury of
> > using a water jacket to keep the barrel cool.
> 
> ..don't.  Use that annular empty space to preheat the air it needs,
> or fill it with e.g. ash to insulate the combustion asd reduction
> zones, you wanna use that heat to make "clean" gas, not tar etc
> vapors. ;o)
> 
> > Presuming the attachment gets through, any comments on the
> > viability of this rather simple downdraft design ?
> 
> ..what do you mean by (4") "10S" in your gas pipe???
> 
> ..stainless steels, titanium etc depends on their surface oxides to
> remain "stainless", in hot dusty reducing environwents like in a
> gasifier outlet pipes, these fancy expensive alloys "corrode" crazy
> much faster than cheap mild steels.
> 
> > Has anyone down a similar unit ?
> 
> ..yup, but a bit smaller, ~200-300kWth, sized for 75kWe on wood and
> MSW.
> 
> > Given the down-draft design it can be run as a batch fuelled unit
> > or semi-continuous fulling. The end user wants to be able to run 24 
> > hours/day 6 days a week at rates from 50 to 500 kW heat output.
> > They will be drawing the gas out to a burner tube using a suction
> > fan on the cool side of a fin tube heat exchanger.
> > 
> > If it works well for heat, then further down the track they will
> > look to pull some of the producer gas off to cooler/filter and into
> > a small diesel engine generator as a co-fuel.
> 
> ..my _guess_ is the K?lle generator will work on your clients damp
> nut shell charcoal if it is indeed tar free, you should be able to
> research and simply scale up the K?lle generator.
> http://gasifiers.bioenergylists.org/taxonomy/term/69
> http://gasifiers.bioenergylists.org/kallegas
> http://www.hotel.ymex.net/~s-20222/gengas/kg_eng.html
> 
> ..ofcourse, this will not work if you do have tars in your charcoal.

-- 
..med vennlig hilsen = with Kind Regards from Arnt Karlsen
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.