[Stoves] Olivier Char-making Stove

Wed Aug 10 00:04:38 CDT 2011

Paul etal see below 

----- Original Message -----
From: "Paul Olivier" <paul.olivier at esrla.com> 
To: rongretlarson at comcast.net 
Cc: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>, "Biochar-production" <Biochar-production at yahoogroups.com>, "Robert Taylor" <rt at ms1.hinet.net>, "Todd Hyman" <toddhyman at live.com>, "loren cardeli" <loren at agrowingculture.com>, dgrowald at gmail.com, "Paul S Anderson" <psanders at ilstu.edu> 
Sent: Tuesday, August 9, 2011 7:58:24 PM 
Subject: Re: Olivier Char-making Stove 

Ron, 

To understand better the burner housing, 
let me present two drawings. 
The first is a drawing of the entire gasifier: 
http://dl.dropbox.com/u/22013094/140%20Gasifier%20Drawings%20in%20PDF/001.pdf 
There you see the burner housing situated at the top of the reactor. 
The second is a drawing of the burner housing: 
http://dl.dropbox.com/u/22013094/140%20Gasifier%20Drawings%20in%20PDF/012.pdf 
The two arrows indicate the flow of secondary air. 
The secondary air rises vertically between the reactor and the burner housing. 
It hits the flange, and its flow becomes horizontal. 
It comes into contact with the burner holes where it combines with the gas, 
and ignition takes place. 

[RWL: I believe I understand now completely. You have some 1 mm clearances radially and the three flanges on the piece with 60 holes does centering of the outermost "secondary" air channel. I think you said somewhere that you could control the vertical spacing between the top two pieces - but I didn't see yet how that was accomplished. But I am sure that would not be difficult. It just was that I didn't see any spacing at all in any of the jpegs with flames. Nice design. You are clearly a good/great designer. 

I do not see anything so special about this design. 
It does not come as a result of a theoretical calculation. 
I drew it in 3-D, it looked good, I had it fabricated and it worked. 
Before this design, I used a housing, 
but the housing did not have the horizontal flange or the one-inch riser ring above it. 

I was not copied on Crispin's answer about the position of the flame. 
Also I did not see the question about a chimney to create a natural draft. 

RWL: I will send those separately. 

A chimney would be awkward in controlling air flow. 
The person using the stove would have only one heat setting based on the height of the chimney. 

RWL: Yes and no. If the primary air supply holes (like your fan entry point) can have their area varied (plugs, rotation of a mask, etc), then this is equivalent to your fan/blower speed control. Too many of the TLUDS don't take advantage of that easy control. We have also talked on this list of having a "flapper" in the chimney, which could give some power control. 

A chimney would also increase the height of the gasifier and would force the reactor to be shorter. 
A shorter reactor means less burn time. 
The small fan consumes very little electricity. 
The amount of electricity consumes (< 1 watt) certainly cannot be an issue. 

I constructed several gasifiers of a 500 mm diameter. 
It is easy to light such a big gasifier. 

I am not sure what you mean by a turn-down ratio. 
If we divide a fairly safe flame height of 8 inches by a half inch (minimal height), 
we get a turn-down ratio of 16. 
Is this what you mean? 
RWL: No (although the flame lengths are certainly going to be similar in ratio). Any power output can be deduced pretty closely by weighing the stove vs time (we may need to know also how much energy is remaining in the char, for energy balancing). Weighing on a bathroom scale is good enough accuracy for this estimate. At your maximum power output, the weight loss rate (dW1/dt in grams per minute or similar) will be much larger than at the minimum power level (call it dW2/dt). 

The ratio of those two numbers is the turn down ratio (have to think this through again - you might have to account for char formation - but I don't think so). With no control over primary air supply, you can only get TDR=1. But you can still can change power level through the weight/density of the fuel load etc.. Sounds like you might be in the neighborhood of 10, which would be fantastic. Better than most electric ranges, maybe 

Sorry for assuming that you had control over secondary air through the fan/blower. You have proven that is not necessary - but you have some control by varying the vertical spacing of the top two burner assembly pieces. The key question here is whether you might have either too much or too little secondary air - a topic that Crispin is good at. A lot will only be known with some emission equipment. 

Lots more questions possible, but we can take that off-line. 

Controlling heat output is very important in a cooking situation. 

RWL: Absolutely - and the more control the better. No rocket stove has any control (or the Anila). They control only through the fuel supply. Sounds like you have virtually infinite variability between the top and lowest desirable power settings. With a fan/blower you especially have control also with different types (densities) of fuel, even with the same desired power out. If you can get a plot of weight vs time for different power settings, that can be an important selling point. It has always amazed me that such plots were so unvarying. You would think that the total air flow resistance would change considerably in an hour or so of pyrolysis as the pyrolysis front moves from top to bottom - nut that was never my experience. 

Thanks. Ron 

Thanks. 
Paul Olivier 

On Wed, Aug 10, 2011 at 6:53 AM, < rongretlarson at comcast.net > wrote: 

Paul, lists and ccs. 

Again thanks for the clarifications. See few notes below. 

From: "Paul Olivier" < paul.olivier at esrla.com > 
To: rongretlarson at comcast.net 
Cc: "Discussion of biomass cooking stoves" < stoves at lists.bioenergylists.org >, "Biochar-production" < Biochar-production at yahoogroups.com >, "Robert Taylor" < rt at ms1.hinet.net >, "Todd Hyman" < toddhyman at live.com >, "loren cardeli" < loren at agrowingculture.com >, dgrowald at gmail.com , "Paul S Anderson" < psanders at ilstu.edu > 
Sent: Tuesday, August 9, 2011 12:35:48 AM 
Subject: Re: Olivier Char-making Stove 

Ron, 

The secondary air rises up between the reactor and the burner housing. 
[RWL: I can't tell how tall this region of secondary air pre-heating is. Do you have a preference for a lot or a short height for this outer cylinder? (I am still not understanding the design completely, I'm afraid. The Bellonia prior work is also new to me. 

The flow of secondary air is not assisted by the fan in any way. 
The fan only supplies primary air. 

Then the secondary air hits a horizontal plate where its flow is changed from vertical to horizontal. 
The horizontal plate runs from the outer wall of the burner housing right to the edge of the outer holes. 
[RWL: This is NOT the horizontal plate seen (only) in (truncated) JPEG 398 ? (full name below). You have not shared any photos or graphic design with this (sounds to be washer shaped) horizontal plate ? It would also help me to see a photo of this horizontal plate you are describing as well as a pot in place. 

The horizontal plate of the burner housing is situated 6 mm above the burner. 
It is easy to lower or raise this gap. 

[RWL: Sorry - I have a vision of a washer shape that is conflicting with the disk-like central horizontal plate of JPEG 398. I am not having a problem with these last two sentences or the next three. ] 

The holes of the outer ring and the inner ring are staggered. 
Thus the secondary air has a theoretically clear path to both sets of holes. 
Note that the gas exits the reactor from both the inner and outer holes of the burner. 
Why flames to not appear right above the burner holes is puzzling. 
Each flame appears in the middle of a triangle - that is, between two outer holes and one inner hole. 
Therefore it is hard to understand how the secondary air reaches the one inner hole in this triangle 
since there is a flame right in its path. 
[RWL: Thanks to Crispin for giving a concise answer.] 

See here the latest design on the burner and burner housing: 
http://dl.dropbox.com/u/22013094/140%20Gasifier%20Jpegs/140%20Gasifier%20Jpegs/001.jpg 
http://dl.dropbox.com/u/22013094/140%20Gasifier%20Jpegs/140%20Gasifier%20Jpegs/002.jpg 

The original flame pattern in the burner design I inherited from Belonio looked like this: 
http://dl.dropbox.com/u/22013094/150%20Burner/IMG_0252.JPG 
[RWL: Which is pretty acceptable for any char making stove. Congratulations to Belonio. I now have to go see anthing more on what he did.] 

Prior developing the concept of a burner housing, 
I tried several burner designs where secondary air is mixed with the gas prior to combustion. 
So instead of this: http://dl.dropbox.com/u/22013094/150%20Burner/IMG_0444.JPG 
I got this: http://dl.dropbox.com/u/22013094/150%20Burner/IMG_0398.JPG 
Not very good. 
All similar efforts to premix failed. 
[RWL: I think the current design looks quite acceptable - without premixing. Very nice looking blue flames. ] 

About your question regarding the turn down ratio, 
I can turn down the fan where the flame height is about a half inch. 
I can turn it up to where the flames height is about one foot. 
But it is not wise to operate a gasifier at such a high speed. 
[RWL: This sounds like a very large turn-down ratio. If you could run with the same fuel loading at the 1/2 inch height and a safe large flame height, the ratio of run-times would be the turn-down ratio. Knowing the times and the weight of the residual char, we can give the power levels pretty exactly assuming about 18 and 30 MJ/kg and using 1 watt = 1 joule/sec. 

The equipment cost per kW of $3.00 is not a typo. 
As the reactor gets bigger, the equipment cost drops. 
In many gasifiers with remote burners, 
this $3.00 per kW would be simply the cost of a remote burner with its pipework, fan and gas cooling equipment. 
I can easily imagine large TLUD gasifiers of a 2-meter diameter and a 4-meter height. 
It is just as easy to light and start-up a large gasifier as a small one. 
In less than 30 seconds one can empty, reload and relight a gasifier. 
[RWL: How large a unit have you constructed? These last two dimensions (2 and 4 meter) should be very attractive to many on these two lists. The only people I recall talking of these sizes have been Alex English (used an aspirator rather than a fan) and Andrew Heggie whose very large unit I saw in 2001 near London. It steam-dried material in place. 

If one cannot be down even for 30 seconds, more than one gasifier could be employed. 
As I explain in my paper, the one reactor can serve as a dryer, a gasifier and a heat exchanger 
without having to touch the reactor or empty it to fulfill all three functions. 
The biomass is dried and gasified, and the char is cooled, without having to move around any solids. 
The fact that the gasifier is equipped with a removable fan makes it so easy to fulfill these three functions. 
[RWL: And this sequencing is well illustrated in one of your papers and also should be of interest to list members. 

I'm sure you will respond more fully to a question today from Crispin on why not use a chimney in place of a fan - but will save suspense by noting you told me in phone call that the rice husks have such a high flow resistance that a chimney is not practical (and would be more costly and bulky). But also we talked about the value of being able to control power for different tasks. Your blower and controller are super cheap. 
I have to repeat my earlier question about lab testing of CO, particulates, etc - at all? 

Again, thanks. Ron 

Thanks. 
Paul 

On Tue, Aug 9, 2011 at 9:04 AM, < rongretlarson at comcast.net > wrote: 

Paul, 2 lists and several ccs: 

Note I have changed the thread name. 

I have viewed your several new jpegs - and again am impressed. It looks different (but much )the same.from your "esrla" site. The quality of the flames looks excellent. Have you been able yet to have any lab combustion testing? 

A few more comments below 

From: "Paul Olivier" < paul.olivier at esrla.com > 
To: rongretlarson at comcast.net 
Cc: "Discussion of biomass cooking stoves" < stoves at lists.bioenergylists.org >, "Biochar-production" < Biochar-production at yahoogroups.com >, "Robert Taylor" < rt at ms1.hinet.net >, "Todd Hyman" < toddhyman at live.com >, "loren cardeli" < loren at agrowingculture.com > 
Sent: Monday, August 8, 2011 5:51:05 PM 
Subject: Re: [Stoves] Jatropha and its future 

Ron, 

It was great talking to you by phone this morning. 

We (four Americans living in Vietnam) are starting a company here in Vietnam call EPWT - 
that is, Empowering the Poor through Waste Transformation. 
The Content section of my old website ( http://www.esrla.com/ ) 
will soon be transferred to the new website ( http://www.epwt.net/ ). 

[RWL: The old one is very informative (and varied). 

Recently we made a lot of improvements in gasifier design, 
most notably, the addition of a burner housing to supply hot secondary air to the burner. 

RWL: It is a little more clear than in our phone conversation. Is the outer ring of holes the entry point for the hot secondary air, and the inner set of holes the exit of the pyrolysis gases? 

For other readers, Paul noted to me in phone conversation that the flame appears in between each set of three holes. It is a surprise to both of us why it should appear that way. Any explanations? (In a burning match the boundaries are all determined by the flow of oxygen molecules inward towards the outward moving escaping pyrolysis gases. In most pyrolysis stove operation, we see the reverse - the oxygen molecules are moving outward from the center of the flame (into the larger volume of pyrolysis gases). Here the flame shape/location doesn't seem to follow those simple rules. In all cases, the emitted light must be (?) where the oxygen molecules meet the gas molecules. Anyone seen this before? Note both gas flows are being pushed by his blower/fan/ 

This allows us to lower the flame to a simmer without danger of the flame going out. 

[RWL: Any estimate possible on this "turn-down ratio" (maximum power level over minimum)? I think some might be able to get 3:1 - but that may be on high side. 

The jpegs were good - but at some point I hope to see cutaways. 

Here is the 150 gasifier in operation with the new burner housing: 
http://dl.dropbox.com/u/22013094/150%20Burner/IMG_0444.JPG 
http://dl.dropbox.com/u/22013094/150%20Burner/IMG_0445.JPG 
Here is the 250 gasifier in operation with the new burner housing: 
http://dl.dropbox.com/u/22013094/250%20Gasifier%20Jpegs/IMG_0523.JPG 
Here is a picture of the same 250 gasifier with the new burner housing: 
http://dl.dropbox.com/u/22013094/250%20Gasifier%20Jpegs/IMG_0513.JPG 
Take a good look at this picture 0513. 
Note the small fan that powers this gasifier. 
It is no bigger than 40x40x28 mm, and is actually too strong for this 10 kW gasifier. 
We operate it at less than 10% of its wattage. 
I will soon be testing this fan to see if it will power the 500 gasifier. 
The 800 gasifier (with an output of up to 100 kW) will require no more than a 60x60x38 mm fan. 
The equipment cost of the larger gasifiers is less than $3.00 per kW. 
[RWL: At first I thought this was a typo. PV is today about 1000 times more costly . (not a fair comparison of course). 

We will be starting the mass production of gasifiers quite soon. 
[RWL: There are not many Biochar equipment manufacturers able to say this. It is great to see this sort of Biochar news this year. 

Many thanks. 
Paul 

[RWL: More thanks to you - and in advance for the questions above. Ron 

On Tue, Aug 9, 2011 at 4:29 AM, < rongretlarson at comcast.net > wrote: 

Stove List: and (added) biochar-production list and adding Robert and (inventor?) Paul 

1. Thanks to Robert Taylor for alerting us to a competitor to the Jatropha - the Chinese Tallow. This plant was new to me - and a plant that looks very interesting (somewhat dangeerous as an invasive species). Apparently in part successful because the Chinese cultivated it and improved it over thousands of years. I think we can well see much the same for many other species -and maybe especially Jatropha. 

2. On the ESRLA site recommended by Robert, I found an excellent long paper also by Dr. Paul Olivier on a really nice looking TLUD stove being manufactured and sold (apparently) in Viet Nam. The paper is at: http://esrla.com/pdf/landfill_06.pdf . 

There is a strong case made there for using a fan - and Paul may well be correct. We should all look more carefully at the advantages of a blower - in saving on fuel costs, but also on convenience and efficiency of being able to control the blower speed. There is a fine looking blue flame in one picture. But mostly I like the professional look and excellent prices on a whole series of models - showing nice economies of scale in pricing. 

I was in Viet Nam earlier this year and am not surprised at the high quality and low costs of commercial products such as are demonstrated in Paul's paper. Their economy is really growing rapidly - and we in the USA are mostly not aware of this big progress.. The Vietnamese are not a typical Communist country - and especially the area in the South around Ho Chi Minh City (HCMC - formerly Saigon). Let's all pull for the Vietnamese to beat out China in the Biochar race! 

His design is very tall and thin - which surprised me. I would like to know if he has also striven to (or could) get a low squat stove. Most unusual of all is that he places a special burner on top of the unit after top-lighting. I have not seen that before.either 

I hope that Dr. Olivier can add some details on his development of this stove, how sales of these TLUDs are going, any problems with any of the fuels he has been using, and also if he has any results from the use of Biochar in the field (improved yield, etc). He makes a very strong case for the economics of using rice husks and rice straw. I also wonder if the Tallow tree fruit (or branches) has been tested in this stove. 

Congratulations to Dr Olivier for two excellent papers. They bear reading twice. 

Ron 

ps After writing the above, I had a substantial phone conversation with Paul (he in Vietnam with a Louisiana phone!). I am even more impressed - and will try to learn more from some other leads he gave. I look forward to further remarks soon from Paul on his pyrolysis stoves - that have some very clever stove innovations and some likely near-term commercial advances.. 

From: "Robert Taylor" < rt at ms1.hinet.net > 
To: "Discussion of biomass cooking stoves" < stoves at lists.bioenergylists.org > 
Sent: Monday, August 8, 2011 2:13:01 AM 
Subject: Re: [Stoves] Jatropha and its future 

Here are some ideas about the Chinese tallow tree (Triadica sebifera, syn 
Sapium sebiferum) from Dr Paul Olivier, who used to post to this list: 

http://esrla.com/pdf/tallow.pdf 

Robert 

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-- 
Paul A. Olivier PhD 
27C Pham Hong Thai Street 
Dalat 
Vietnam 

Louisiana telephone: 1-337-447-4124 (rings Vietnam) 
Mobile: 090-694-1573 (in Vietnam) 
Skype address: Xpolivier 
http://www.esrla.com/ 

-- 
Paul A. Olivier PhD 
27C Pham Hong Thai Street 
Dalat 
Vietnam 

Louisiana telephone: 1-337-447-4124 (rings Vietnam) 
Mobile: 090-694-1573 (in Vietnam) 
Skype address: Xpolivier 
http://www.esrla.com/ 

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