[Stoves] A continuous feed rice husk gasifier for parboiling 40 kg of rice?

[Paul Anderson]

Dear Serge and Abraham,

The photos from Serge are very helpful.   Photos from Abraham will show 
the larger system that they use.

There are a few questions and issues.

1.  How important is it to convert to using the rice husks as fuel for 
the parboiling process?   I believe that use of the rice husk as fuel is 
NOT the priority.   As Serge and Abraham have stated, the main concern 
is to reduce the use of large amounts of wood. Appropriately sized TLUD 
gasifiers with wood fuel (or Rocket burners of sticks) could accomplish 
the task of reducing the amount of wood being burned.   This would be 
with natural draft.

2. _IF _rice husks are to be used with a TLUD gasfier, it would required 
Force Air (or Fan Assistance) (FA), and that would require a small 
amount of electricity.   With the parboiling being done in the daytime, 
a solar cell could be used, even without a battery.   What are the 
availabilities of small electrical power in the locations of either 
Abraham's or Serge's operations?

3.  Please comment on the frequency of doing the parboiling task.   
Abraham, is your operation run every day?   Frequency of use can impact 
favorably the ability of maintain equipment such as a fan unit or 
battery / solar package.

4.  For the 25 L quantities described by Serge, there is really no need 
to have a continuous operating gasifier.   Either the unit could be 
large enough for the stated durations of usage (30 minutes to raise to 
80 C; and one hour for the steaming).   To boil away (evaporate) 6 L of 
water in one hour can be accomplished; but some attention should be paid 
to the configuration under the pot, such as possibly having a pot-skirt 
or other ways to improve heat retention and heat transfer.   This is NOT 
a situation requiring a good turn down ratio to obtain Low Power cooking.

5.  As we close in on the topic, we need to discuss who will lead the 
efforts (management) to accomplish the tasks, and who will pay for the 
expenses (finances).    Strong communications via email are quite 
important.  Skype is useful.   Access to some sheet-metal workers is 
important for the fabrication of the TLUDs.   The cost of materials 
should not be very high, but the issues and costs of management and 
labor can be easy or difficult, depending on the circumstances.

6.  Are Serge and Abraham close together, and working together? If not, 
each should describe their specific situations.    Please send us your 
views of possible plans for moving forward.

Dr TLUD

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

On 2/18/2015 5:01 AM, Serge Horsmans wrote:
> Dear Paul (and other insiders),
>
> thank you very much for your attention to my request.  Below you will
> find the questions and the answers.  Please ask for more information
> if needed.
>
> 1.  What heat source(s) are you currently using?   Do you have
> batch-operations of rice husk gasifiers already?   What is good and
> what is bad about them?
>
>   At the moment we are using fire wood as the heat source.  We are not
> using gasifiers and I don't have any experience with them, but it
> seems to me that continuous flow gasifiers are more appropriate since
> once the heating of the soak water or the steaming is started, it
> should not be interrupted by refilling the batch.  It is hard to find
> gasifiers in Africa.
>
> 2.  Is your operation the only one, or could there be other similar
> businesses that might also want to improve their heat sources?
>
>   I am not too much aware of the other businesses, but it is easy to
> guess that if it is affordable technology, it will as well be adopted
> by local restaurants.  For one or other reason this technology didn't
> reach Africa yet.
> In Benin, it is mainly women that parboil rice.   Recently a new
> device for parboiling has been introduced to improve the quality of
> the parboiled rice.  An educational video, in which rural women
>   explain how to use the improved rice-parboiling technology and its
> benefits, was
>   developed by AfricaRice in 2005 to promote this technology to
> end-users.  The video-supported training tool has contributed
> significantly to the
>   diffusion of the technology in Central Benin. This video has been
> used by many NGOs. It is now the common device in Benin. So the same
> might be done with the gasifier.  All organisations that support those
> women might adopt the gasifiers as they all want to reduce the use of
> fire wood.
>
> 3.  I assume that all of the associated structures are in place,
> functional, and are expected to be part of the new operation.
> Structures such as the large vessels (pots, trays, cauldrons, etc.)
> and also the boiler.
>
> Yes, though I don't know what you mean about the boiler... it is just
> wood placed below the cauldron  .
> Any heat source that can be used to heat water in a cauldron could be
> used as the device is basically a cauldron containing about 25 l. of
> water for soaking the paddy.   The same cauldron is afterwards used
> for steaming the paddy with about 6l. of water ( I will add some
> pictures).  Since firewood and charcoal have always been used and is
> easily available, they continue to use firewood or charcoal.   By
> introducing the gasifiers we would like to reduce the use of firewood.
> - Soaking process:  heat paddy in 25 l. of water to a temperature of
> about 80°C, it takes about 30 min.   Next let it cool down during the
> night in the cauldron.
> - Steaming process:   You take a paddy holding vat and a cauldron (a
> similar cauldron as for the soaking). The  paddy holding vat is
> perforated with holes (maximum diameter 2.5 mm) from its base to about
> a quarter
>   of the way up its body . The paddy rice is poured into
>   the vat, which is inserted in the cauldron containing 6l. of water.
> The water level in
>   the cauldron is such that it does not reach the bottom of the paddy
> holding vat.  The improved
>   method prevents water in the cauldron from getting into the paddy,
> only the steam
>   generated from the boiling water in the cauldron passes through the
> perforated vat to
>   parboil (steam) the paddy rice.  It takes about 1 hour.
>
> 4.  Please send us some photos of the existing installation. There are
> issues such as height of the boiler above ground that can influence
> what options could be for the new "fire box."
>
> I will add some.  Please ask for more if needed.
>
> 5.  Are you or others in your area interested in biochar from the rice
> husks?   If so, a pyrolyzer (rather than a full process gasifier)
> might be more appropriate.
>
> Hard to say.  The women parboiling the rice are not same as the ones
> cultivating the rice.   So they will not use the biochar as a soil
> conditioner.  I have no clear idea what could be done with biochar...
>
> Thanks again  for your attention to my request.   I 'm looking forward
> to hear from you again.
>
> Kind regards,
>
> Serge
>
>

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