[Stoves] Characteristics of biochar was Re: [biochar] grassifier & cedar chip char

Tue Feb 5 08:17:19 CST 2013

Dear Stuart and Paul

The elemental analysis (ultimate analysis) of residual char is an important topic of future investigation and it is surprising how little has been done. There are coal analysis methods that are popular and routine, however they are not just misleading, they can be highly misleading if you take them to be a list of what is in the fuel. They are more like a study of the result of systematised char-making than elemental analysis.

The concept that throws people off is that of ‘fixed carbon’ as if there was some carbon in the fuel that will not pyrolyse. Even if there was, it is not a measure of the total carbon in a fuel.

So the lower temperature pyrolysis does not only increase the amount of volatiles, and it is also not only the carbon in those volatiles that may or may not be missing. It is not simple at all and the only way to investigate the result is with systematic analysis of the elements in the resulting product. In addition, for practical reasons, one would want to know the chemical contents because while knowing the total quantity of each element, or at least MASHCON as we call it for HTP calculations, the type and % of volatiles is still important.

Lighting very low volatiles high-carbon fuels is much more difficult than the converse. That matters a lot when designing a cooking system. I know there are serious implications for buried char when the wrong volatiles are manufactured in the hot, organic chemical-filled spaces in the pyrolysing fuel. The literature suggests that in Japan they are very specific about the type of fuel and heat treatment needed to get the ‘right’ product for biochar use.

So there are two paths here. The Low path of knowing what is in the fuel so chemically balanced test methods can be applied and the High path with the Low + the chemical nature of everything that has been manufactured in the ‘retort’.

I would settle for a middle path of knowing that the Moisture Ash Sulphur Hydrogen Carbon Oxygen and Nitrogen are (MASHCON) plus the % mass of volatiles. It is difficult enough to get that at a reasonable cost.

Regards

Crispin

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Paul Anderson
Sent: Tuesday, February 05, 2013 4:57 AM
To: stuart mather; Discussion of biomass cooking stoves
Subject: Re: [Stoves] Characteristics of biochar was Re: [biochar] grassifier & cedar chip char

Stuart and all,

On 2/3/2013 10:21 PM, stuart mather wrote:

That's great, thanks Paul,

So the higher % yield of lower temp char is only extra weight from ungasified volatiles, and not because less of the carbon structure is being combusted? In a no oxygen environment, no carbon can combust, no matter how high the pyrolysis temp can it?

And I suppose there's also the issue of recalcitrance. Do you know the figures for increased recalcitrance from a higher pyrolysis temp.?

Stuart.

The chemistry is important here.  In the biomass are many carbohydrate (C & H & O) molecules.  They are NOT elemental carbon (C).   Char is produced by pyrolysis, which uses heat, whether with or without a flame present.  Carbonization/pyrolysis (2 sides of the same coin) is the only way to make char at the surface of the Earth.   Carbon that is called coal is by pressure and heat underground (or in a laboratory).

More than this, we need some chemists to fill in the picture to answer your questions.

Paul

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com
  _____  

From: Paul Anderson  <mailto:psanders at ilstu.edu> <psanders at ilstu.edu>
To: biochar at yahoogroups.com 
Cc: stuart mather  <mailto:kneebraceboy at yahoo.com.au> <kneebraceboy at yahoo.com.au>; Hugh McLaughlin  <mailto:wastemin1 at verizon.net> <wastemin1 at verizon.net> 
Sent: Monday, 4 February 2013 2:00 AM
Subject: Characteristics of biochar was Re: [biochar] grassifier & cedar chip char

Dear Stuart, Trent and all,

On 2/3/2013 6:32 AM, stuart mather wrote:

Tom, 

Isn't the most compelling reasons for keeping the temp low is that the yield is higher. If one of the motivations

 for making biochar is to sequester C, then minimizing the amount of CO2 you emit to the atmosphere in actually making the biochar would seem to be prudent, wouldn't it? 

Higher yields (as measured by weight) do not mean that more of the "right kind of C" is created or put into the soil.  Higher weights are usually associated with having more of the volatiles remaining in the char structure.  So,

Charcoal at minimal temps (I think about 300 - 350 C) have a lot of carbon remaining as  volatiles (mobile, can be leached in soils, hurting plants), which is good if you are trying to ignite it in a charcoal cooker.   

Charcoal at 450 C (in my opinion) is the bottom range of what is decent to be used as biochar.

Charcoal at 550 C to 800 C has less weight, but a larger percentage is the desired carbon structures for good biochar.  Very few volatiles.   And has higher adsorption capacity.   

McLaughlin has a great chart showing this but I cannot find it right now.

Please see the paper on the internet:    All biochars are not created equal....    By McLaughlin, Anderson, Shields and Reed (2009)   Also available at my website 
 http://www.drtlud.com/resources/publications-and-multimedia/entire-catalogue/

 I understand that if you need to cook with biomass then  a Tlud is clearly the way to go. But can it be argued that people in the developed world would be doing the climate a favour by cooking food with a TLUD too, and leaving the fossil fuel gas or electric powered stove gathering dust.

I certainly like to read comments like that!!!   

And there is certainly room for a lot more efforts by interested people.

Paul

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com <http://www.drtlud.com/> 
  _____  

From: Tom Miles  <mailto:tmiles at trmiles.com> <tmiles at trmiles.com>
To: biochar at yahoogroups.com 
Sent: Sunday, 3 February 2013 2:58 PM
Subject: RE: [biochar] grassifier & cedar chip char

David,

Nitrogen in wood and straw forms ammonia and ammonia like compounds during pyrolysis. That is what you are smelling. Collectively they are called NOx precursors. When burned they become Nitrogen oxide emissions (NOx). As you suggest the TLUD is a more oxidizing environment and so you don’t see the same ammonia formation.

The assumption that 450C is magic for all applications has to be further tested. We have anecdotally seen very good results with gasifier chars which are subjected to much higher (>600-800 C) temperatures. It is likely that TLUD chars are subjected to these higher temperatures. 

Tom

From: biochar at yahoogroups.com [mailto:biochar at yahoogroups.com] On Behalf Of trent
Sent: Saturday, February 02, 2013 8:36 PM
To: biochar at yahoogroups.com
Subject: Re: [biochar] grassifier & cedar chip char

Well Don, the noose is just hanging there empty so I am going to put my head in it.  Looking to scale up and have tried a couple different things including using propane/natural gas. Until proven otherwise, I don't see how you can achieve a steady, consistent burn to account for biomass variables in MC, density, etc. and produce the volume needed to make a profit on industrial sizing.  Steel went away from charcoal to reduce costs.  There is a lesson there.  If 450C (842f)  is the number being bandied about for ideal commercial biochar, its going to take a lot of processed biomass burned or wasted, to keep a continous kiln at that temperature. Processing biomass as fuel isnt cheap.  Using a combination of gas and the biogas, industrial ceramics and automation to create an oxygen free enviroment, opens up all kind of doors.  I have a very simple design in mind which can run 24/7 with gas and was wondering if anyone could recommend someone with a little more engineering expertise than my UHK degree to fill in some blanks. 

http://news.rice.edu/2012/03/22/cooking-better-biochar-study-improves-recipe-for-soil-additive/

  _____  

From: David Yarrow <dyarrow5 at gmail.com>
To: biochar at yahoogroups.com 
Sent: Saturday, February 2, 2013 12:02 AM
Subject: Re: [biochar] grassifier & cedar chip char

On Feb 1, 2013, at 9:12 PM, Trent Lund wrote:
> David
> Do you think you could char a bale of straw or is it pressed to tight?

hi trent,

i've thought about that. ideally, we can design a burner that can char an entire hay bale without extra handling. might require a fan to improve the air flow thru the feedstock. the round stalks of hay and straw may allow significant leeway in how tight they can be packed together and still allow air to flow up through the stalks. dust is a further issue that can shut down air flow.

currently, i use a TLUD, which requires air to be sucked up through the biomass. experience is this device is finicky and temperamental, and particle size and feedstock density is a significant issue. often i have to screen wood chips through 1/4-inch hardware cloth to separate out the dust and finer particles, or the TLUD chokes, the gas flare goes out, and a smoky, stinky burn results. i'm concerned hay, straw, weeds, even cornstalks might similarly choke my TLUD, so my first test burn last weekend with hay for feedstock, i was careful to loosen the stalks of the tightly packed hay bale and pack it in the barrel loosely but firmly.

in the next two months, i will do more test burns with a variety of weedy materials. i will experiment to see how tight i can pack hay or straw without choking the updraft.

two years ago, i was using a 55/30-gallon kiln & retort to char sticks and limbs of applewood for saratoga apple orchard. apple is denser than oak or maple, and harder to ignite and burn. what worked well was to loosely pack straw with the applewood. straw gasifies faster that wood, and kickstarts pyrolysis until temperatures are intense enough to gasify the denser applewood. worked so well the applewood limbs would shatter into small chunks, making them easier to process into soil mixes.

curiously, i discovered that a freshly opened retort with straw char emitted such strong ammonia odor it would knock my head back. never got to fully explore what that was, but it seemed certain the ammonia was coming from the straw. with a TLUD, i doubt ammonia will be created, or if so, it will be oxidized and burnt off in the gas flare.

david

__._,_.___

 <http://groups.yahoo.com/group/biochar/post;_ylc=X3oDMTJyajk2ZWIzBF9TAzk3MzU5NzE0BGdycElkAzIyNDM4MDUyBGdycHNwSWQDMTcwNzQxODYxMgRtc2dJZAMxNDQ3MgRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzEzNTk4OTQ3NzY-?act=reply&messageNum=14472> Reply via web post 

 <mailto:kneebraceboy at yahoo.com.au?subject=Re%3A%20%5Bbiochar%5D%20grassifier%20%26%20cedar%20chip%20char> Reply to sender 

 <mailto:biochar at yahoogroups.com?subject=Re%3A%20%5Bbiochar%5D%20grassifier%20%26%20cedar%20chip%20char> Reply to group 

 <http://groups.yahoo.com/group/biochar/post;_ylc=X3oDMTJmc2ZiazEwBF9TAzk3MzU5NzE0BGdycElkAzIyNDM4MDUyBGdycHNwSWQDMTcwNzQxODYxMgRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzEzNTk4OTQ3NzY-> Start a New Topic 

 <http://groups.yahoo.com/group/biochar/message/14460;_ylc=X3oDMTM3aGloNnFnBF9TAzk3MzU5NzE0BGdycElkAzIyNDM4MDUyBGdycHNwSWQDMTcwNzQxODYxMgRtc2dJZAMxNDQ3MgRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzEzNTk4OTQ3NzYEdHBjSWQDMTQ0NjA-> Messages in this topic (10) 

Recent Activity: 

·          <http://groups.yahoo.com/group/biochar/members;_ylc=X3oDMTJncjFnbDk2BF9TAzk3MzU5NzE0BGdycElkAzIyNDM4MDUyBGdycHNwSWQDMTcwNzQxODYxMgRzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxMzU5ODk0Nzc2?o=6> New Members 2 

 <http://groups.yahoo.com/group/biochar;_ylc=X3oDMTJmMWZ1Y3FoBF9TAzk3MzU5NzE0BGdycElkAzIyNDM4MDUyBGdycHNwSWQDMTcwNzQxODYxMgRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzEzNTk4OTQ3NzY-> Visit Your Group 

 <http://groups.yahoo.com/;_ylc=X3oDMTJlZ3Bla2M0BF9TAzk3NDc2NTkwBGdycElkAzIyNDM4MDUyBGdycHNwSWQDMTcwNzQxODYxMgRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTM1OTg5NDc3Ng--> Yahoo! Groups

Switch to:  <mailto:biochar-traditional at yahoogroups.com?subject=Change%20Delivery%20Format:%20Traditional> Text-Only,  <mailto:biochar-digest at yahoogroups.com?subject=Email%20Delivery:%20Digest> Daily Digest •  <mailto:biochar-unsubscribe at yahoogroups.com?subject=Unsubscribe> Unsubscribe •  <http://docs.yahoo.com/info/terms/> Terms of Use •  <mailto:ygroupsnotifications at yahoogroups.com?subject=Feedback%20on%20the%20redesigned%20individual%20mail%20v1> Send us Feedback 

.

__,_._,___

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20130205/9f6d0f01/attachment.html>