[Stoves] Continuous gasifier for household scale - experience sharing

[Paul Anderson]

Dear SNV and Tuong DoDuc,

I have not worked with continuous feed rice-husk gasifiers.   I have had 
success with using dry woodchips/pellets, but not financially viable at 
household level.

The rice husk expert is Alexis Belonio.   I am sending him a copy of 
this message because he does not always read all of the Stoves Listserv 
messages.   I suspect that he would agree with the remainder of my message:

Note:  Your current level of activities are already advanced because 
your starting point is  based on the Belonio work.   And your level of 
questions cannot really be addressed via email messages.   What is 
needed is hands-on work by experienced people with advanced equipment 
(at least PEMS-level measurements) with a timetable and a budget that 
can cover some serious expenses by the best people.   Or go to Belonio, 
paying your own way and paying something to him and the entity where he 
is working, and there you will find answers with real depth.

Opinion:  An organization the size of SNV (and others) should bring in 
the assistance you need, or be prepared to re-plow the same fields 
(re-inventing the same wheel) that Belonio and others have done at 
considerable personal expense and sacrifice.

Technical note:   I have for a long time been impressed by the beautiful 
blue flames from the rice husk gasifiers.   But your materials call 
attention to soot deposition from these flames. So I conclude that the 
blue flames from rice husk should not be equated with the super-clean 
combustion with blue flames from natural gas, LPG, biogas and alcohol.   
Super-clean burning is harder to do than meets the eye that sees blue 
flames.

Your work is to be commended, and encouraged to continue.   But this is 
serious research.   And I do not normally associate SNV with such 
technical research (but I could be mistaken). Somebody needs to get this 
work done, and I hope that SNV and others will put the needed resources 
into resolving these important issues.

And the studies need to address the issues of cost of a device that is 
targeted to serve single households.   Even when a unit such as you are 
constructing is functional, it might not be affordable or even 
appropriate for the HOUSEHOLD target.   Maybe for restaurants???    or 
for small commercial needs such as significant heating of water for 
hotels, etc.???

Dr TLUD

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

On 5/13/2013 8:23 PM, Tuong DoDuc wrote:
> Dear Dr.TLUD, Paul Oliver, and others,
>
> The team in SNV Vietnam is adopting the continous gasifier model 
> developed by Belonio. The manual has been obtained from the CRHET.
> Watch our first propotype: http://www.youtube.com/watch?v=xQGS-VQIj5M
> We were able to control the fire, load fuel without affecting the 
> fire, and easily remove char at the bottom of the reactor.
>
> We also adopted the computer fan-casing by a cheaper, more popular fan 
> in Vietnam (often used for coal and fixed wood stove). Fan costed 2USD 
> (while to replicate Belonio's fan-casing, we bought the adapter for 
> 5USD and a computer fan for 1.5USD)
>
> However, this is just our first step and we still have so many 
> problems to fully control the fire and ease the operation.
> 1) For instance, uncontrolled moment happened when combustion occurs 
> rigt on top of the fuel hopper, a lot of smoke was produced and later 
> the fire burnt the fan.
> https://www.dropbox.com/s/43fkjs0axuye4oj/uncontrollable_moment.jpg
> https://www.dropbox.com/s/rd1g1cg0a9ue8qt/fan_casing.jpg
>
> 2) Another problem is that a lot of tar is produced. It deposits on 
> pot bottom, burner and other part of the stove. That would also harm 
> the user. An idea is to create a layer of char in the burner pipe (to 
> filter the tar). Not tried yet.
>
> 3) We observes 5-10% of the gas leaked out through the char removal 
> door. We burnt them, but user may not know (or they simply just don't 
> care) that it is toxic.
>
> 4)  One more, it is very hard to control the final minutes of the 
> gasificatoin process. It always cause inverted combustion to the fuel 
> hopper.
>
> By this email, I would like to ask if some of you have done similar 
> work with continuous gasifier like this to share more experience. We 
> can thus reduce our time and effort in localizing this technology.
>
> Best regards,
>
> Do Duc Tuong,
>
> Renewable Energy Advisor
> SNV Vietnam
>
>
>
>
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