[Stoves] Equipment required for testing stoves

Thu Dec 6 14:03:30 CST 2012

Josh (cc list) 

Nice data - thanks for sharing. 

Several questions: 

a. In the ND case, I am surprised that the upper thermocouple showed a sharp drop about 25 minutes prior to the almost identical drops of the lower two. It is almost as if it fell out - as the dark black curve came back near the end.. Your explanation? 

b. There was somewhat similar behavior in the FD case, but no "falling out". I would have expected all probes to have dropped in temperature about the same time and manner - why the upper probe behaving differently? Faster cooling due to secondary air nearby? 

c. You had quite a tall chimney - so the device could not operate as a stove. Do you have any data on the maximum temperature with a shorter chimney in the ND cases (which might then better simulate a stove)? This further queried next. Did you have a means of controlling primary air other than through the chimney height? 

d. Can you supply the weight of the starting and ending weights of the load of pellets in each case. It appears that the FD power level was close to twice the power level (half the duration) of the ND case. It would be interesting to see the thermocouple measurements with 0 (?), 1, 2, and 3 extra cans above the secondary air inlets as well as for your case of four upper cans. 
In other words - how low a temperature char could be obtained? I have seen no data on char temp as a function of power (primary air flow rate) - so your geometry offers a nice (non-stove) way to prepare chars which should have very different in-soil characteristics. 
In a stove, changing the power levels (fuel duration time) through changes in primary air supply (changing the turn-down ratio) would have a similar effect - and I have seen no previous data on this phenomenon . Is such data out there? 

e. There were several cans below the fuel can with the 3-4 thermocouples. What was their purpose? 

Ron 

----- Original Message -----
From: "Josh Kearns" <yeah.yeah.right.on at gmail.com> 
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org> 
Sent: Wednesday, December 5, 2012 4:17:10 PM 
Subject: Re: [Stoves] Equipment required for testing stoves 

The attached file shows our experimental 1-gal "Toucan" TLUD with temperature probes inserted through the reactor body into the char bed at various depths, and some representative data from charring pine pellets with this unit. You can see that in ND mode, char temperatures reach ~ 650 C, and in FD mode ~ 900 C. (The high temperature spikes at the bottom of the reactor at the end of the run indicate char combustion as the pyrolysis front has descended all the way and air encounters hot char.) 

Also note that this is in Boulder, CO at over 5,000 ft elevation - we would expect slightly higher temperatures at lower elevations where the air is not so thin. 

For charring pine pellets, we typically see an 80% mass loss in ND mode, and a 90% mass loss in FD mode, with corresponding volume reduction of about 1/2 and 2/3. 

Josh 

On Wed, Dec 5, 2012 at 3:36 PM, Paul Olivier < paul.olivier at esrla.com > wrote: 

Josh and Saastamoinen, 

A terracotta vase is quite inexpensive and will resist the high temperature of the hot biochar. 
When rice hull biochar is emptied from the reactor, a good portion of it is red hot. 
It would be easy to measure the temperature of the biochar, but I have never done this. 
Josh's guess that hot biochar approaches the melting point of aluminum appears reasonable. 

Rice hulls do not allow for the easy passage of air, 
and rice hull biochar is even more resistant than rice hulls to air flow. 
So rice hull biochar has excellent insulative properties. 
A half hour after pouring hot biochar into a vase, 
the vase is still quite hot to the touch and must be handled with caution. 

The terracotta vase that I have designed is not heavy 
and can be placed on the dining room table to keep a dish warm. 

It is important that the volume of biochar match the holding capacity of the vase. 
In this way there are no large pockets of air within the vase. 
In gasifiying 12 liters of rice hulls in the 150 gasifier, we are left with about 6 liters of biochar. 
So I designed the vase to hold this volume of biochar. 

In gasifying coffee husks, we see little reduction in volume. 
Twelve liters of coffee husks produce twelve liters of biochar. 
Two terracotta vases would be needed in this case. 

Thanks. 
Paul 

On Wed, Dec 5, 2012 at 11:37 PM, Josh Kearns < yeah.yeah.right.on at gmail.com > wrote: 
> 
> I would be wary of using aluminum - it melts around 660 C and the char in gasifier stoves can well exceed this temperature. 
> 
> Josh 
> 
> 
> On Wed, Dec 5, 2012 at 12:17 AM, Paul Anderson < psanders at ilstu.edu > wrote: 
>> 
>> Frank, Crispin and all, 
>> 
>> For Frank's needs in testing labs in affluent countries, the suggested methods could include the following (combining thoughts from several contributors): 
>> 
>> 1. Dry Ice (solid CO2), Can be weighed if the CO2 is an issue. Worth a try, but watch out for the expansion of the gases. (Usually cooling involves contraction, but the dry ice will greatly expand.) 
>> 
>> 2. ALUMINUM disks or squares or washers. Ball have undesirable thickness. Flat will take the heat quickly. And can be separated easily and re-weighed if suspected char dust clinging to the objects is a quantity of concern (unlikely). 
>> 
>> For testing labs without access to dry ice (distribution or financial limitations), consider the aluminum flat objects. These can be made easily in any developing country. Melting of aluminum drink-cans will do the job. 
>> 
>> Also, ceramic "snuffer containers" (such as Paul Olivier's) might be designed to receive the aluminum pieces and allow tumbling (the ceramic will take some of the heat) and then be placed in a container with water to further pull away the heat. Having written this, I now add: Why bother with the weight and fragility of ceramics? Just get a metal container (aluminum could be superior) with an appropriate lid and even a know weight. Cooled and can be weighted inside the container. 
>> 
>> Paul (in Kampala) 
>> 
>> Paul S. Anderson, PhD aka "Dr TLUD" 
>> Email: psanders at ilstu.edu Skype: paultlud Phone: +1-309-452-7072 
>> Website: www.drtlud.com 
>> 
>> On 12/4/2012 6:41 PM, Frank Shields wrote: 
>> 
>> Ron, 
>> 
>> I think there is a misunderstanding of my intent. The method I use in the lab is intended for just measuring the energy at a snap shot of time (WBT test ends) and then dumping the char in the dumpster. What you and others mention is another subject (quenching char for sale). The cost of water, nitrogen, argon, CO2 and other gases are a non-issue for the small amount we would use and we make up the cost from the clients wanting the tests. 
>> 
>> 
>> 
>> Thanks 
>> 
>> 
>> 
>> Frank 
>> 
>> 
>> 
>> From: rongretlarson at comcast.net [mailto: rongretlarson at comcast.net ] 
>> Sent: Tuesday, December 04, 2012 3:57 PM 
>> 
>> 
>> To: Discussion of biomass cooking stoves 
>> Cc: Crispin Pemberton-Pigott; Frank Shields; Elisha Moore-Delate 
>> Subject: Re: [Stoves] Equipment required for testing stoves 
>> 
>> 
>> 
>> List and ccs 
>> 
>> I haven't seen mentioned today a possible approach that might solve some of the indicated problems for extinguishing a char-making batch stove. This is the same that I mentioned to a smaller group a day or so ago. The idea would be to use a rock dust that one might want anyway for improving the char's soil augmentation properties. Some rock dusts are like biochar - carbon negative (as an oxide, hydroxide, sulfate etc changes with time over to a carbonate). 
>> 
>> It would be simple to weigh (maybe just measure the volume of) the rock dust placed on top of the hot char to block air flow. If char is eligible for carbon credits, then the combination should be worth even more (the exact ratio of credits needs work). 
>> 
>> A white "quenching" powder might even get additional credits for improving the albedo. 
>> 
>> I think we are in agreement that we don't want to use water, nitrogen (costly) or CO2 (costly), but I think dirt (or sand/clay, etc - as suggested by Elisha) is also OK - as long as we weigh the amount used to extinguish. When one needs to measure and characterize the char, then a "vase" technique like Paul Olivier has suggested is probably needed. But smothering a bed of char which something that adds value to the char sounds easier to apply/manipulate than moving the hot char. 
>> 
>> I am assisting with a project to collect data on biochar and rock dusts (and even better their use together) in field-performance. I'd love to hear from anyone with such data. 
>> 
>> Ron 
>> 
>> ________________________________ 
>> 
>> From: "Crispin Pemberton-Pigott" < crispinpigott at gmail.com > 
>> To: "Discussion of biomass cooking stoves" < stoves at lists.bioenergylists.org > 
>> Sent: Tuesday, December 4, 2012 3:14:13 PM 
>> Subject: Re: [Stoves] Equipment required for testing stoves 
>> 
>> 
>> Use an aluminum plate! 
>> 
>> 
>> 
>> One problem would be the size of the char and the fact there is unburned torrefied wood inside some char. It won’t crush easily. It is a reason the error on the estimated heat value in the char is large. 
>> 
>> 
>> 
>> Regards 
>> 
>> Crispin 
>> 
>> 
>> 
>> 
>> 
>> From: Stoves [mailto: stoves-bounces at lists.bioenergylists.org ] On Behalf Of Kevin 
>> Sent: Wednesday, December 05, 2012 12:09 AM 
>> To: Discussion of biomass cooking stoves 
>> Subject: Re: [Stoves] Equipment required for testing stoves 
>> 
>> 
>> 
>> Dear Frank 
>> 
>> 
>> 
>> What about 2 steel pie plates? Put char in one and cover with the other. 
>> 
>> 
>> 
>> If char was very hot, to enhance cooling rate, set the bottom plate on a paper towel soaked in water, and spray the top plate with a water mist. 
>> 
>> 
>> 
>> Best wishes, 
>> 
>> 
>> 
>> Kevin 
>> 
>> ----- Original Message ----- 
>> 
>> From: Frank Shields 
>> 
>> To: 'Discussion of biomass cooking stoves' 
>> 
>> Sent: Tuesday, December 04, 2012 5:14 PM 
>> 
>> Subject: Re: [Stoves] Equipment required for testing stoves 
>> 
>> 
>> 
>> Paul, 
>> 
>> 
>> 
>> I like the vase. And having a pot of water on top collecting ‘energy’ as the WACW cools seems like a great method of measuring energy loss during the cooling that can be added on to the values determined from a ground and tested WACW. Wonder if that would work - Crispin? 
>> 
>> 
>> 
>> Frank 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> From: Stoves [mailto: stoves-bounces at lists.bioenergylists.org ] On Behalf Of Paul Olivier 
>> Sent: Tuesday, December 04, 2012 12:41 PM 
>> To: Discussion of biomass cooking stoves 
>> Subject: Re: [Stoves] Equipment required for testing stoves 
>> 
>> 
>> 
>> Frank, 
>> 
>> Getting an accurate dry weight of biochar is indispensable in being able to sell it. 
>> If we douse the biochar with water, then we no longer have an accurate measurement of dry weight. 
>> Also biochar right out of the gasifier contains valuable heat that could be used in keeping food warm. 
>> 
>> Therefore I designed a terracotta vase to contain the hot biochar. 
>> A pot placed on top of the vase prevents oxygen from entering. 
>> The vase shown in the drawing below can hold six liters of biochar. 
>> This is the volume of rice hull biochar produced in my 150 gasifier. 
>> https://dl.dropbox.com/u/22013094/150%20Gasifier/Terrecotta%20Vase/Drawing/Terracotta%20Vase.pdf 
>> 
>> Thanks. 
>> Paul Olivier 
>> 
>> On Wed, Dec 5, 2012 at 3:20 AM, Frank Shields < frank at compostlab.com > wrote: 
>> 
>> Hi Crispin, 
>> 
>> Weighing the fuel when removed (hot and burning) and dry weight after 
>> soaking with water, draining (screen) and drying is not a convenient 
>> procedure to determine moisture left -and prone to error - but only method I 
>> can think of at the moment. 
>> Water puts out a fire by taking away its heat. So wondering if there is 
>> another method that could be used? Combination nitrogen gas and pieces of 
>> steel in a tumbler? Must be some way besides water. 
>> 
>> Frank 
>> 
>> 
>> Frank Shields 
>> Control Laboratories, Inc. 
>> 42 Hangar Way 
>> Watsonville, CA 95076 
>> (831) 724-5422 tel 
>> (831) 724-3188 fax 
>> www.biocharlab.com 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> -----Original Message----- 
>> From: Stoves [mailto: stoves-bounces at lists.bioenergylists.org ] On Behalf Of 
>> Crispin Pemberton-Pigott 
>> Sent: Tuesday, December 04, 2012 11:26 AM 
>> To: Stoves 
>> Subject: Re: [Stoves] Equipment required for testing stoves 
>> 
>> Dear Frank 
>> 
>> You are on the right track, in my view. The assumed energy for the wood and 
>> char is a major source of imprecision in the test. 
>> 
>> As for quenching with water: unfortunately we need to know the residual 
>> moisture content of the fuel 'as removed'. That varies a lot depending on 
>> the stove type. Quenching it with nitrogen is an alternative. 
>> 
>> Regards 
>> Crispin 
>> -----Original Message----- 
>> From: "Frank Shields" < frank at compostlab.com > 
>> Sender: "Stoves" < stoves-bounces at lists.bioenergylists.org > 
>> Date: Tue, 4 Dec 2012 10:19:39 
>> To: 'Discussion of biomass cooking stoves'< stoves at lists.bioenergylists.org > 
>> Reply-To: Discussion of biomass cooking stoves 
>> < stoves at lists.bioenergylists.org > 
>> Subject: [Stoves] Equipment required for testing stoves 
>> 
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>> -- 
>> Paul A. Olivier PhD 
>> 27/2 Phu Dong Tieng Vuong 
>> 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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> 
> 
> -- 
> Josh Kearns 
> PhD Candidate 
> Environmental Engineering 
> Engineering for Developing Communities 
> University of Colorado-Boulder 
> 
> Director of Science 
> Aqueous Solutions 
> www.aqsolutions.org 
> 
> Mobile: 720 989 3959 
> Skype: joshkearns 
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-- 
Paul A. Olivier PhD 
27/2 Phu Dong Tieng Vuong 
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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-- 
Josh Kearns 
PhD Candidate 
Environmental Engineering 
University of Colorado-Boulder 

Director of Science 
Aqueous Solutions 
www.aqsolutions.org 

Mobile: 720 989 3959 
Skype: joshkearns 

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