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moisture in coal combustion

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Old   June 12, 2003, 21:50
Default moisture in coal combustion
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Sheng
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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
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Old   June 13, 2003, 06:34
Default Re: moisture in coal combustion
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Stanislav Pagur
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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
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Old   June 14, 2003, 09:25
Default Re: moisture in coal combustion
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zhhqxp
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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?
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Old   June 15, 2003, 19:43
Default Re: moisture in coal combustion
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Sheng
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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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