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: [email protected] 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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