[Gasification] 500 kW Gasifier concept

[James Joyce]

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 ? 

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

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 .. 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). 

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.

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

Regards,

James


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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.