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

[Paul Anderson]

Dear Serge and Abraham,

I am not sure in what country Abraham lives.   Please tell us. It is 
interesting that two messages about parboiling of rice arrived so close 
together in time.

The rest of this message relates to Serge's message:

1.  Please confirm the following:
A.  The people who parboil the rice are doing it as a business.
B.  Do those same people remove the husks from the barboiled rice?   If 
yes, then they have control over their own fuel supply, which is good.

C.  The rice must reach a temperature of 80 deg C.   But how critical is 
it that the time to reach that temperature is about 30 minutes?   What 
if it took 45 minutes?   or only 20 minutes? Does that have any impact 
on the rice itself?

D.  How do the people know that it has reached about 80 C? 
Thermometer?   Visual seeing of small bubbles rising?   Touch? That does 
not make any difference.   I am just curious.

E.  The steaming of the hot wet rice is the crucial step.   We will try 
for boiling (evaporating away) 6 L of water in one hour.   But how 
sensitive is that time?    And if the time needs to be close to one 
hour, and if the stove is boiling away the water too fast, is it 
acceptable to have 7 or 8 liters for creation of the steam.   In other 
words, steam (at 100 deg C) needs to pass through the rice.   Is the 
amount of steam (from 6 liters of water) the important issue, or is 
steam for one hour (whether from 6 or 7 or 8 liters) the important issue?

2.  Joe James (who is receiving this message) has recently worked on a 
rice husk TLUD gasifier that should be able to accomplish the specified 
tasks.   Joe is an engineer and can crank out some of the numbers.   
Also some other members of this Stoves Listserv could be of assistance.  
Here are the questions:
How much heat is needed to vaporize 6 L of water?
Raise 6000 g of water from about 25 C to 100 C
(75 degree change x _______ Joules per gram x 6000 = ___________)
Then add in the latent heat needed for vaporizing the 6000 g.

Divide that total amount of heat by 60 minutes.

Determine how much rice husk is needed to get the needed heat (allow for 
efficiency of heat transfer to be as low as 30%.)

This not my specialty, but I know it all can be calculated.   Also to 
calculate the heat needed to bring the pot to 80 deg C in the first 
phase of the processing.  A little assistance would be appreciated.

Then we see how much heat Joe's unit (called JJQuad TLUD) can put out.   
The unit can be made larger or smaller, and having 2 units might be the 
better option.   Or we increase the air flow (via the fan) to get faster 
pyrolysis, and maybe we need to have a refill of fuel into the batch 
gasifier.   This does not take long to refill and reignite.

3.  Subject to actually making things happen, in my opinion the best 
"evident" option is to have a rice husk gasifier provide the heat by 
using the husks from the rice as fuel for the parboiling businesses are 
creating.

4.  The production of at JJQuad TLUD is being examined in Vietnam at 
this time.   We are assisted with this by Dylan Maxwell and Olivier 
Kolmel, who are also receiving this message.  There are issues being 
examined about fans and controls and metal quality and production.   
This is not a quick solution, but it is quite viable, in my opinion.

5.  Serge, I would like to know about the number of parboiled-rice 
producers you are considering could need such a solution.   Also, please 
tell us about metal working (thin sheet metal) capabilities in Benin, 
and accessible.  Also, I would appreciate information about you and your 
involvement and situation (with an NGO?).

It might be time for this conversation to not be on the Stove Listserv, 
or after any replies by Joe or Dylan and Olivier.   Any readers who have 
continuing interest should probably tell me and Serge so that we can 
keep you informed.

Paul

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 2/19/2015 5:21 AM, Serge Horsmans wrote:
> 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
>>>
>>>
>>