[Stoves] carbonates in Ash

[frank]

Dear Philip, Crispin,


IPC wrote:

>There are basically two sources of carbonates in the ash:
>- carbonates in the feed material
>- carbonates formed by reaction of basic materials formed during combustion
>with CO2.  For example Ca(OH)2 + heat ----> CaO + H2O followed by CaO + CO2
>----> CaCO3.  
>If the temperature gets high enough, the second reaction can reverse, and
>give you CaO from both sources.  This can then confuse things by adsorbing
>CO2 from the atmosphere as the ash cools. If you want to experiment, be
>careful to quench the ash as soon as possible with water.
>  
>
 From the atmosphere or from the wood - I guess it doesn't matter 
because if from the wood it must first form CO2 (doing the heat thing) 
before it forms the carbonates. And forming the carbonates involves 
little heat. If we want to use the unburned carbon left in the ash (to 
determine the carbon used to produce heat) we must make sure we first 
remove the inorganic carbonates before doing the total carbon analysis 
because the carbon in the carbonates has already been used.   If I 
understand this right. Thanks


>The adsorption of CO2 will generate a little heat, but it is certainly
>within the limits of measurement error for the overall combustion and can be
>ignored.
>
>Hope that helps.
>
>(Dr)Philip Lloyd
>Energy Research Centre
>University of Cape Town
>Private Bag Rondebosch 7701
>South Africa
>Tel +27 (0)21 650 3896
>Fax +27 (0)21 650 2830
> 
>
>-----Original Message-----
>From: stoves-bounces at listserv.repp.org
>[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Crispin
>Pemberton-Pigott
>Sent: 16 January 2008 07:43
>To: 'Discussion of biomass cooking stoves'
>Subject: Re: [Stoves] carbonates in Ash
>
>Fear Frank
>
>It seems to me that if there was more than that to start with, then it
>should be deducted as in _can_ burn but did not. If the level did not drop
>because it can't burn, then it counts as ash
>
>Regards
>Crispin
>
>  
>
>>Should this carbon be taken off the carbon in the wood when
>>    
>>
>calculating  energy  produced from the wood? 
>
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>
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-- 
Frank Shields
Soil Control Lab
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