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Sheng June 12, 2003 21:50

moisture in coal combustion
 
Can anybody share experience on considering the moisture in coal on pulverised coal combustion?

I am simulating coal combustion. I am using two-mixture fraction model to define coal composition in prePDF, where I used empirically defined stream for the secondary stream (volatiles stream).

In my simulation, I need consider the influence of the moisture of coal on the combustion. My question is how to represent the moisture content in prePDF. Should I use the atomic fraction (i.e. H and O) to represent H2O as defining the secondary fuel stream, or by other ways?

Any response on this poster would be appreciated.

SCD

Stanislav Pagur June 13, 2003 06:34

Re: moisture in coal combustion
 
Hi Sheng, If you don't insert are water as independent substance (it is correct but tricky way) and insert H an O as elements you need to modify high heat of combustion - some heat would used to water evaporation. Also it would change flame temperature distribution Also note that water reacts with carbon, produce carbon monoxide and hydrogen and other substances.

BR, Stas

zhhqxp June 14, 2003 09:25

Re: moisture in coal combustion
 
i am interested in this question. the moisture reduce the peak temperature and the NOx emissions change, who has the experience about the pulverized coal combustion modelling with the consideration of the moisture. can you share it?

Sheng June 15, 2003 19:43

Re: moisture in coal combustion
 
Stanislav,

Thanks a lot for your response.

I had ever used the water as an independent substance. However, because high moisture means lower fuel heat value, sometime the prePDF calculation couldn't be performed. I increased the heating value in prePDF and compensated it in FLUENT (considered the latent heat for volatile. But as using 1 mixture model, the compensation value is a problem. Moreover, just as you said, such kind input is a tricky way.

Thanks again


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