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

Thu Feb 19 05:21:30 CST 2015

Dear Paul and ,

Thank you very much for your quick response.  Please find the answers
to the questions asked.

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.

At this moment I have to list the possibilities of not using firewood
in the parboiling process.   The use of a rice husk gasifier seems to
me one of those possibilities.  So I would like to continue with rice
husk, as it is easily available.  So at this moment I would like to
answer the question, “Is somebody using a rice husk gasifier that that
can heat water to a temperature of about 80°C in about 30 min.?  And
can the same stove be used to boil away 6 l. of water In about 1 h.?”.
If there is such a stove I would like to know and I will added to my
list.  Next we might want to test that one first.

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?

I was aware that fan assistance would be needed.  We do have the
possibility to provide the required electricity.

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.

Maintenance will not be a problem.

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.

We will use the configuration you can see on the pictures where the
rice is steamed or use a pot skirt.  We might not need a continuous
operating gasifier but as the operations will be performed outdoor,
wind or other environmental factors might slow down the heating,
requiring more fuel.  What ever type we will use, we need to make sure
that the parboiling can be finished.  The aim of our study is to
improve the livelihood of the rice parboilers in Benin.  If the
parboiling process cannot be finished, the paddy might get spoiled and
they will not have an income, they will loose the money they used to
buy the paddy instead.  That should be avoided.   So if we go on with
batch gasifiers, we might have to oversize the unit.

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.

It is going very fast now and I 'm very happy with your enthusiasm !
But as you can read in the answer on your first question, right now I
am listing the possibilities of not using firewood in the parboiling
process.  So my first question is, can we banish firewood using those
stoves?  Or more in detail, I want to know “Is there an existing rice
husk gasifier that that can heat water to a temperature of about 80°C
in about 30 min.?  And can the same stove be used to boil away 6 l. of
water In about 1 h.?”.     If there is not such a stove, we will have
to compare  the different  possibilities to banish firewood in the
parboiling of rice in Benin.  The rice husk gasifiers will be an
option.  Next we might consider to design one ourselves and your help
will be really appreciated.  As we have experience in Benin with
dissemination of new technologies, we might start to built them and
provide them.  But we are not that far yet.

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.

I would like to know more about Abraham and his project.   As
mentioned we are in Benin and at the moment I live in Savalou,
department Les Collines.  For my view, please read my answer on
question 5.  I like to know more about your views.

Thank you very much!

Kind regards,

Serge

2015-02-18 19:30 GMT+01:00, Paul Anderson <psanders at ilstu.edu>:
> 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
>>
>>
>
>