[Stoves] Saving the WBT

Tue Aug 20 08:44:47 CDT 2013

Paul,

I said Free energy, not unlimited free energy. If you were to tip out the
contents from the pipe onto a white sheet of paper you would be looking at
the free energy you have to do with whatever you want. Buts that's all you
get. Some needs to be used to raise the temperature for pyrolysis of the CHO
complexes to occur. Some to pre-treat the volatile complex organics to more
combustible forms for when it reaches the secondary. What's left you can
take home and sprinkle around your plants. 

Regards

Frank

Frank Shields

Control Laboratories; Inc.

42 Hangar Way

Watsonville, CA  95076

(831) 724-5422 tel

(831) 724-3188 fax

frank at biocharlab.com

www.controllabs.com

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Paul Olivier
Sent: Monday, August 19, 2013 9:25 PM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Saving the WBT

It was written:
When the fuel is wet we have all that FREE energy from the catalyst that
will evaporate it IN the stove body.

When water is transformed from a liquid to a gas within the reactor, it
takes considerable energy to do this, and the process temperature is
lowered. A high temperature is needed for the Boudouard reaction to take
place (C+ CO2 gives 2 CO) and for the water gas reaction to take place (C +
H2O gives CO + H2). So if the moisture content increases beyond what is
optimal (10 to 12%), there is less CO, more CO2 and more H2O in the gas.
Biomass has to be carefully dried, otherwise the reactions within the
reactor are compromised, and stove efficiency drops.

Thanks.

Paul Olivier

On Tue, Aug 20, 2013 at 10:27 AM, Ronal W. Larson
<rongretlarson at comcast.net> wrote:

Frank and list:

    see below.

On Aug 19, 2013, at 4:08 PM, "Frank Shields" <frank at compostlab.com> wrote:

Dear Crispin, Ron, and all,

When I now think about all this it all seems so simple and obvious as the
way to do it. Not sure if others are following me in my thinking.

     [RWL1.  I still am not.

All we need to do is have all start with the same Energy from a biomass and
use that as a baseline when comparing stoves. Oven dry weight energy value
minus the char in the pipe. When burning wet (real) biomass we just report
that in the 6 Box reporting sheet so a lower (or higher if the water
reaction) results can be explained.   

    [RWL:  I see no way testing can start with "same energy", unless this
means some average energy density (such as 18 MJ/kg).  But this varies with
moisture content and the variation with different fuels is all over the
place.  I gave a cite for a paper on this last week where Tom Miles was a
co-author.  Huge variations and complexities.

When the fuel is wet we have all that FREE energy from the catalyst that
will evaporate it IN the stove body.

     [RWL:  Sorry.  I mistrust the idea of free energy - and especially with
the words "catalyst" and "evaporate in".  Can you give an example or a cite?

In fact, if one puts a cup of water in a stove the evaporated steam hitting
the pot will increase the water temperature in the pot. Unless the steam
lowers the temperature of the secondary, or otherwise interferes with the
secondary combustion,

     [RWL:  Both seem likely]

it will add to the energy heating the water. It cost nothing to evaporate
the water.  

     [RWL:  I think it WILL cost something.  If not, we would see a lot more
of it than we do.  I know of only one stove with an added water supply - and
don't think it is commercial.  Anyone?

As for coal: I have not thought how this would work and know little about
burning coal. I would think it much like adding char to a rocket stove?
There being little secondary combustion and the stove body getting very
hot(?)

     [RWL:  Cooking with coal is a horrible idea - and China has the
environment to prove it.  Yes - using a rocket stove to combust char is as
bad an idea as in a TLUD.   Jikos aren't all that great but they are
infinitely better than a rocket.

In my own mind I think this is what really happens in the real world and it
seems clear to me this is the direction we should go. 

     [RWL:  I presume the two words "this" refer to different topics.  But
the whole point of the stoves list is to find better ways to go than todays
"real world".  This is a subject that badly needs new ideas and expertise.
I would avoid following the "real world" like the plague.  In the "real
world", the forest will be gone in a few decades.

And if we can make it work it would simplify stove testing immensely.  

    [RWL:     Big "if".  Your being in a testing lane  should make it easier
than for most of us.

     Please review what I wrote last time.  I think it great you are
offering other approaches, but I can't see any way your testing one (?)
small sample of anything in a pipe helps anything in stove analysis.  If
others understand this, please let me know what I am missing. 

   Jim Jefford is already getting the energy content of every sample (wood
blocks, pellets, rice husks, whatever) used in testing stoves.  He is in a
webinar at 10 AM Eastern, 7AM Pacific tomorrow - possibly talking on this
topic.  His having been doing this full time for many years, you (anyone)
can pop any question in you wish to a world expert.

Ron

Regards

Frank

Frank Shields

Control Laboratories; Inc.

42 Hangar Way

Watsonville, CA  95076

(831) 724-5422 tel

(831) 724-3188 fax

 <mailto:frank at biocharlab.com> frank at biocharlab.com

 <http://www.controllabs.com> www.controllabs.com

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Crispin Pemberton-Pigott
Sent: Monday, August 19, 2013 1:45 PM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] Saving the WBT

Dear Frank

It is a difficult question to answer. Do you want the actual energy
available from a particular piece of wood or the heat theoretically
available, or what it would be if it was dry?

If the fuel is moist, then the gasification or the volatiles energy has to
evaporate that moisture to get it out of the way. Unfortunately the amount
of gas you can make from a bit of wood literally changes with the moisture
level because the moisture is involved in the chemistry of what happens in
the processes.

With respect to coal, I was not even about to get a carbon content of the
'volatiles' let alone an energy figure.

I suspect you are not going to get a good answer, and whatever answer you
get is not going to be very useful in a real world problem.

Regards

Crispin

Dear Stovers,

I am trying to determine the best way to calculate the energy in the Natural
Volatiles. The sample we place in the iron pipe of the oven dried biomass we
can test or 'look up' the energy value. In the char remaining after 450c
deg. (char-ash) we can give that a value of 34.78 kJ/g. Then for the total
NV in the fuel we just subtract the total biomass from the char energy
remaining. All done in the pipe. Then use the energy calculated from the
increase temperature of the water to determine efficiency.

I am still wondering what to do with the moisture in the fuel. Any
suggestions?

It is like the NV fraction but with possible varying results. As Alex
reminded me in his writings there is the water-reaction that can increase
the energy output or the LHV stealing energy from the NV. So depending on
the stove and operator working the catalyst to control the internal body
temperature the water can be a plus or minus.  My thinking now is to just
use the dry NV value as the total energy of the biomass. Like playing golf.
You have a par 5 and you can go above or below depending on your day. The
dry NV value is the value we use and we go above or below 100% efficiency
depending on how good the stove and operator controls the catalyst and if
water is included in with the biomass.

>From the replies it's a bit hard to tell but it seems we are mostly all in
agreement. : )

Regards

Frank

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-- 
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