[Gasification] Re: blue flame observations in TLUD rice husk gas stove

[psanders at ilstu.edu]

All,

The message below from Alexis Belonio (not subscribed to our lists, so please
include his address in any replies) gives measurements that I hope some of you
can analyze and comment upon.  Are his numbers what you would expect from
pyrolyzing a kilo of fuel?

Alexis, please explain more about:
> (Note that burner design
> also affects the color of the flame).

I will forward his reply to the listserves.

I think this is important to understand how you can get such a clean-appearing
flame from a T-LUD gasifier, the only ones so far that use fine-particle fuel
(rice husk), allow for remote combustion of the gases (not close-coupled), and
have a blue flame.

For pictures and many pages of quality discussion, see his "Handbook" at
http://bioenergylists.org/contributors#Belonio

Paul


Quoting alexis belonio <atbelonio at yahoo.com>:

> Dear Paul,
>
> Thanks for the email!
>
> In our TLUD Rice Husk Gas Stove, I used 1.2 to 1.6
> cubic meter of air per kg of rice husk.  You need to
> distribute this air depending on the time you desire
> to gasify rice husk. If you have an electric blower,
> you can control the air flow by using the dimmer
> switch or if the blower is DC, you can control it with
> a variable conventer.  There is a need to do the
> actual adjustment and control of the fan depending on
> the stove design since different stove designs have
> different types of burner. (Note that burner design
> also affects the color of the flame).
>
> In addition to airflow, the superficial gas velocity
> at the reactor of the stove should be kepth below 9
> cm/sec. Too much airflow will fluidize rice husk char.
> Normally the pressure draft at the reactor is about 1
> cm per meter depth of rice husk fuel.
>
> Note that the above observations only hold thru in our
> TLUD stove using rice husk as fuel.
>
> Alexis
>
> --- psanders at ilstu.edu wrote:
>
>> Stovers,
>>
>> The following is from Alexis Belonio.  He is not
>> subscribed to the Stoves list
>> serve, so please include his address in any replies
>> that you send.
>>
>> Alexis, please tell us more about the amounts of
>> primary air that give
>> the best
>> gases.  I suspect that a moderate to strong flow of
>> primary air is best.  If
>> really strong flow, than what is observed?  And if a
>> low flow, what is
>> happening?  So far you are the only person who has
>> these observations, so your
>> details are important.
>>
>> Tom Reed, I still do not know why you say that blue
>> flame is not better
>> than the
>> yellow flame, or however you choose to say it.
>> Please elaborate.
>>
>> Paul
>>
>> Quoting alexis belonio <atbelonio at yahoo.com>:
>>
>> > Dear Paul,
>> >
>> > Thanks for the email and the info re blue flame
>> from
>> > gasification of biomass!
>> >
>> > In my previous experiments on TLUD rice husk
>> > gasifiers, I found the following factors
>> contributed
>> > in producing a bluish flame color:
>> >
>> >   1. The fuel itself - Only rice husk was found to
>> > have a bluish color in the stove.  I tested wood
>> > chips, corn cobs, and dried leaves. The rice husk
>> > produced the bluish color of almost 80 to 90%
>> followed
>> > by crumbled dried leaves  of about 60 to 70% then
>> corn
>> > cobs of 30-40%, and wood chips of 5-10%.
>> >
>> >   2. The moisture content of rice husk fuel -
>> Based
>> > on my several tests, drying rice husk in the sun
>> for
>> > half a day produces a better flame (more
>> bluish)than
>> > rice husk which is not subjected to drying before
>> > fuelling.
>> >
>> >   3. The type of burner used - The design of the
>> > burner also affects the color of the flame.  The
>> > cylindrical type cover produces a better flame
>> than
>> > the conical cover.  This can be attributted either
>> to
>> > the distribution of secondary air or the
>> preheating
>> > effect of air prior to combustion.
>> >
>> >   4. Amount of char in the reactor - The amount of
>> > char also affects the color of the flame. During
>> the
>> > first few minutes, the color of flame is less
>> bluish
>> > than on the later stage of the stove operation.
>> This
>> > is because more char layer is present in the stove
>> in
>> > the later part of operation than in the earlier
>> part,
>> > that improves gas generation.
>> >
>> >   5. Amount of air flow - Adjusting the amount of
>> air
>> > during gasification can provide the right color of
>> the
>> > flame during gasification.  I observe this in the
>> > single as well as in the remote burner stoves.
>> >
>> > These observations might not be true to other
>> biomass.
>> > The stove itself should be tested and experiments
>> must
>> > be done.
>> >
>> > Alexis
>> >
>>
>>
>>
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