[Stoves] [biochar-production] Re: Stoves Digest, Vol 14, Issue 17

[Tom Miles]

Frank,

We use the elemental ash analysis in gasification and combustion to
determine the potential for slagging, fouling or volatilization, refractory
selection, etc. Ash from grasses contains high concentrations of potassium
and sometimes sodium that vaporize at low temperatures and combine with
chlorine or sulfur. The fine submicron droplet is sticky and can cause
fouling. when it condense son metal parts it can start corrosion. 

We normally use thermal ash preparation following ASTM D1102 (Test Method
for Ash in Wood) at 600C (1112 F) to reduce alkali loss during sample
preparation. 

US Bureau of Mines (now NETL) Laboratory at Albany, Oregon also developed a
microwave dissolution technique for us that I will send to you separately. 

Tom    

-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
Sent: Thursday, October 27, 2011 1:14 PM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14, Issue
17

Tom,

What do you do with the results from an elemental analysis of the ash? For
disposal or potential slagging, nutrients? Reason is I wonder what the best
method of digestion to get the elements for analysis. 





Frank Shields
Control Laboratories, Inc.
42 Hangar Way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com
 
 

-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Tom Miles
Sent: Thursday, October 27, 2011 12:29 PM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14,Issue
17

When requesting an ash elemental analysis we always ask for CO2 as an
indication of carbonates formed. CO2 is higher in grasses than in wood,
sometimes CO2 is 15% of the ash sample.

Tom

-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
Sent: Thursday, October 27, 2011 12:34 PM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14, Issue
17

Good point!  Perhaps I need to rethink this. In woody materials the
carbonates will be formed as the cations are set free. But in char (as you
point out) they likely formed during the process using oxygen and carbon
from the wood. And perhaps the ash content (550 deg C with oxygen) is a true
ash reading. Thanks.

This is a great group.

Frank 



 
Frank Shields
Control Laboratories, Inc.
42 Hangar Way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com
 
 
-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
ajheggie at gmail.com
Sent: Thursday, October 27, 2011 1:06 AM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14,Issue
17

On Wednesday 26 October 2011 21:54:47 Frank Shields wrote:
> Because we 'make' more ash when we
> change the cations into carbonates (increasing weight) during the
> process. More cations from vegetative matter the more the problem. And
> this quantity of ash is not what we are spreading on the field. Also
> the carbon trapped in the ash (as CO3) is not included in the fixed
> carbon fraction - it should be because it comes from the organic carbon
> in the raw sample.

Just picking up on one small point in your post: I infer that you are 
saying as the sample is heated to  higher temperatures in the "ashing" 
process, to drive off remaining volatiles, carbonates form. In fact I 
suspect these are also a feature of chars from gasifiers.

I don't think this carbon can count as recalcitrant as it will be gassed 
off as CO2 in acid conditions.

AJH



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